JP2019050104A - Method for manufacturing positive electrode active material composite for lithium ion secondary battery - Google Patents

Abstract

To provide a method for manufacturing a positive electrode active material composite for a lithium ion secondary battery, which enables an efficient manufacturing process and which allows a resultant secondary battery to exhibit superior durability and an excellent rate characteristic.SOLUTION: A method for manufacturing a positive electrode active material composite for a lithium ion secondary battery, which includes particular lithium composite oxide particles composed of lithium composite oxide secondary particles (A) and having particular lithium-based polyanion particles (B) coating surfaces of the lithium composite oxide secondary particles, comprises the steps of: (X) firing mix powder including a predetermined compound to obtain lithium composite oxide secondary particles (A); (Y) granulating, by spray drying, a slurry including lithium-based polyanion primary particles obtained by subjecting a predetermined compound to a hydrothermal reaction and a carbon source and then, firing resultant granules, thereby obtaining granulated bodies (C) consisting of lithium-based polyanion particles (B) having carbon supported on their surfaces, and adjusted to 45-80 vol.% in porosity; and (Z) mixing the lithium composite oxide secondary particles (A) obtained in the step (X), and granulated bodies (C) obtained in the step (Y) while applying a compressive force and a shearing force thereto, thereby compounding the lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B) having carbon supported on their surfaces while collapsing the granulated bodies (C).SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a positive electrode active material composite for a lithium ion secondary battery having a layered rock salt structure, which can obtain a lithium ion secondary battery having both excellent discharge characteristics and safety.

  Layered lithium composite oxides such as layered lithium-nickel-cobalt-manganese composite oxide (NCM) and layered-type lithium-nickel-cobalt-aluminum composite oxide (NCA) comprise a lithium atomic layer and a transition metal atomic layer Has a layered crystal structure alternately stacked via an atomic oxygen layer, and has a so-called layered rock salt structure in which one lithium atom is contained per one transition metal atom. Such layered lithium composite oxide is used as a positive electrode active material that can constitute a high output and high capacity lithium ion secondary battery.

  In a lithium ion secondary battery using such a layered lithium composite oxide as a positive electrode active material, charging and discharging are carried out by the lithium ions being desorbed and inserted into the layered lithium composite oxide. As the discharge cycles are repeated, capacity reduction occurs, and particularly when used for a long time, the capacity reduction of the battery may be significant. It is believed that this is because the dissolution of the transition metal component of the layered lithium composite oxide into the electrolytic solution during charging easily causes the collapse of the crystal structure. In addition, the elution of the transition metal component into the electrolytic solution may lower the thermal stability of the lithium ion secondary battery and impair the safety.

However, for example, a battery material used for a vehicle-mounted battery is required to have excellent durability such that a battery capacity of a predetermined level or more can be maintained even after a large number of cycles of 1000 cycles or more. There have been various developments to accommodate this. For example, in Patent Document 1, the surface of lithium nickelate particles is generally represented by Li _x MPO ₄ (0.05 ≦ x ≦ 1.2, M is Fe, Mn, Co, Ni, Cu, Zn, Mg) And a positive electrode active material coated with an olivine compound represented by at least one selected from the group consisting of lithium nickelate having good electron conductivity, and an olivine compound having excellent cycle characteristics and safety. By setting it as the positive electrode active material used together, the improvement of the charge / discharge capacity and high temperature stability as this whole positive electrode active material is aimed at. And, as the olivine compound to be used, the one obtained by the method of baking a precursor obtained by mixing predetermined raw materials in a reducing gas atmosphere as described in Patent Document 2 is used as the olivine compound to be used Is also described.

JP 2004-87299 A JP 2001-250555 A

  However, when producing a positive electrode active material in which the surface of lithium nickelate particles is coated with an olivine compound as described in Patent Document 1 above, it is obtained by the method as described in Patent Document 2 above. When using an olivine compound, such an olivine compound is a very robust secondary particle, so it may require an excessive load to break it up, and the coating process may also take time. Therefore, in these particles constituting the positive electrode active material, there is a concern that damage to the crystal structure may occur and be expanded, and battery characteristics such as durability and rate characteristics may be degraded in the obtained secondary battery. .

  Therefore, an object of the present invention is to manufacture a positive electrode active material composite for lithium ion secondary battery capable of exhibiting excellent durability and rate characteristics in the obtained secondary battery while making the production process efficient. It is to provide a method.

  Therefore, as a result of intensive studies to solve the above problems, the present inventors have found that lithium formed by coating a specific lithium-based polyanion particle (B) on the surface of a specific lithium composite oxide secondary particle (A) In the production of a positive electrode active material complex for an ion secondary battery, the efficiency of the production process is achieved by using a granule having a high porosity, which is formed of lithium-based polyanion particles (B) having carbon supported on the surface. It has been found that it is possible to obtain a positive electrode active material capable of improving battery characteristics while achieving

That is, the present invention relates to the following formula (I) or (II):
LiNi _a Co _b Mn _c M ¹ _x O ₂ (I)
(In the formula (I), M ¹ represents Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, And one or more elements selected from Bi and Ge, a, b, c, x, 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, Indicates a number satisfying 0 ≦ x ≦ 0.3 and 3a + 3b + 3c + (valence of M ¹ ) × x = 3)
LiNi _d Co _e Al _f M ² _y O ₂ (II)
(Wherein M ² is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi, and D represents one or more elements selected from Ge, d, e, f and y each satisfy 0.4 ≦ d <1, 0 <e ≦ 0.6, 0 <f ≦ 0.3, 0 ≦ It shows a number satisfying y ≦ 0.3 and 3d + 3e + 3f + (valence of M ² ) × y = 3)
In the surface of lithium composite oxide secondary particles (A) consisting of lithium composite oxide particles represented by the following formula (III):
LiFe _m Mn _n M ³ _o PO ₄ (III)
(In the formula (III), M ³ represents Co, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. M, n, and o satisfy 0 ≦ m ≦ 1, 0 ≦ n ≦ 1, 0 ≦ o ≦ 0.3, and m + n ≠ 0 are satisfied, and 2m + 2n + (valence number of M ³ ) × o = 2 is satisfied.)
A method for producing a positive electrode active material complex for a lithium ion secondary battery, comprising the step of coating a lithium-based polyanion particle (B) having a surface supported by carbon and being supported on the surface, comprising the steps of Z):
(X) A lithium mixed oxide containing a lithium compound, a nickel compound, a cobalt compound, and a manganese compound, or a mixed powder containing a lithium compound, a nickel compound, a cobalt compound, and an aluminum compound is fired to form a lithium composite oxide Obtaining secondary particles (A),
(Y) A lithium compound, a metal compound containing at least an iron compound or a manganese compound, and a phosphoric acid compound are subjected to a hydrothermal reaction, lithium-based polyanion primary particles obtained, and a slurry containing a carbon source are spray-dried to granulate And calcining to adjust the porosity to 45 to 80% by volume, and obtaining a granulated body (C) comprising lithium-based polyanion particles (B) having carbon supported on the surface, and (Z ) The lithium composite oxide secondary particles (A) obtained in step (X) and the granules (C) obtained in step (Y) are mixed while applying compressive force and shear force to produce A positive electrode for a lithium ion secondary battery, comprising a step of combining the lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B) having carbon supported on the surface thereof while disintegrating the particles (C) Active material The present invention provides a method for producing a complex.

  According to the manufacturing method of the present invention, it is possible to effectively avoid applying an excessive load in the process, and effectively suppress the damage of the crystal structure in the particles constituting the positive electrode active material while enhancing the efficiency of the manufacturing process. Thus, it is possible to obtain a positive electrode active material complex for a lithium ion secondary battery having stable durability and rate characteristics.

Hereinafter, the present invention will be described in detail.
The method for producing a positive electrode active material composite for a lithium ion secondary battery of the present invention comprises the following formula (I) or (II):
LiNi _a Co _b Mn _c M ¹ _x O ₂ (I)
(In the formula (I), M ¹ represents Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, And one or more elements selected from Bi and Ge, a, b, c, x, 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, Indicates a number satisfying 0 ≦ x ≦ 0.3 and 3a + 3b + 3c + (valence of M ¹ ) × x = 3)
LiNi _d Co _e Al _f M ² _y O ₂ (II)
(Wherein M ² is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi, and D represents one or more elements selected from Ge, d, e, f and y each satisfy 0.4 ≦ d <1, 0 <e ≦ 0.6, 0 <f ≦ 0.3, 0 ≦ It shows a number satisfying y ≦ 0.3 and 3d + 3e + 3f + (valence of M ² ) × y = 3)
In the surface of lithium composite oxide secondary particles (A) consisting of lithium composite oxide particles represented by the following formula (III):
LiFe _m Mn _n M ³ _o PO ₄ (III)
(In the formula (III), M ³ represents Co, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. M, n, and o satisfy 0 ≦ m ≦ 1, 0 ≦ n ≦ 1, 0 ≦ o ≦ 0.3, and m + n ≠ 0 are satisfied, and 2m + 2n + (valence number of M ³ ) × o = 2 is satisfied.)
A method for producing a positive electrode active material complex for a lithium ion secondary battery, comprising the step of coating a lithium-based polyanion particle (B) having a surface supported by carbon and being supported on the surface, comprising the steps of Z):
(X) A lithium mixed oxide containing a lithium compound, a nickel compound, a cobalt compound, and a manganese compound, or a mixed powder containing a lithium compound, a nickel compound, a cobalt compound, and an aluminum compound is fired to form a lithium composite oxide Obtaining secondary particles (A),
(Y) A lithium compound, a metal compound containing at least an iron compound or a manganese compound, and a phosphoric acid compound are subjected to a hydrothermal reaction, lithium-based polyanion primary particles obtained, and a slurry containing a carbon source are spray-dried to granulate And calcining to adjust the porosity to 45 to 80% by volume, and obtaining a granulated body (C) comprising lithium-based polyanion particles (B) having carbon supported on the surface, and (Z ) The lithium composite oxide secondary particles (A) obtained in step (X) and the granules (C) obtained in step (Y) are mixed while applying compressive force and shear force to produce A step of combining the lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B) having carbon supported on the surface while collapsing the particles (C) is provided.

The step (X) provided in the method for producing a positive electrode active material composite for lithium ion secondary batteries of the present invention comprises a lithium compound, a nickel compound, a cobalt compound, and a mixed powder containing a manganese compound, or a lithium compound, a nickel compound And calcining a mixed powder containing a cobalt compound and an aluminum compound to obtain a lithium composite oxide secondary particle (A). The lithium composite oxide secondary particles (A) obtained in this step have the following formula (I) or (II):
LiNi _a Co _b Mn _c M ¹ _x O ₂ (I)
(In the formula (I), M ¹ represents Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, And one or more elements selected from Bi and Ge, a, b, c, x, 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, Indicates a number satisfying 0 ≦ x ≦ 0.3 and 3a + 3b + 3c + (valence of M ¹ ) × x = 3)
LiNi _d Co _e Al _f M ² _y O ₂ (II)
(Wherein M ² is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi, and D represents one or more elements selected from Ge, d, e, f and y each satisfy 0.4 ≦ d <1, 0 <e ≦ 0.6, 0 <f ≦ 0.3, 0 ≦ It shows a number satisfying y ≦ 0.3 and 3d + 3e + 3f + (valence of M ² ) × y = 3)
Lithium secondary oxide particles represented by Formula (I), secondary particles represented by Formula (II), and lithium secondary oxide particles represented by Formula (I): Both the particles (A) are particles having a layered rock salt structure constituting the positive electrode active material.

In order to obtain the lithium composite oxide secondary particles (A) represented by the above formula (I), a mixed powder containing a lithium compound, a nickel compound, a cobalt compound, and a manganese compound is fired. Specifically, an aqueous solution a is preferably obtained by first dissolving a nickel compound, a cobalt compound, and a manganese compound in water so as to obtain a desired lithium composite oxide composition. Examples of such nickel compounds, cobalt compounds and manganese compounds include sulfates, nitrates, carbonates, acetates, oxalates, oxides, hydroxides, halides and the like of these metal elements. Specifically, nickel sulfate, cobalt sulfate, manganese sulfate, nickel acetate, cobalt acetate, manganese acetate and the like can be mentioned, but it is not limited thereto.
In this step, Mg, Ti, Nb, Fe, Cr, as a metal (M ¹ ) element which substitutes a part of the lithium composite oxide so as to obtain a desired lithium composite oxide composition as required. One or more elements selected from Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and Ge may be mixed. .

  Next, an alkaline solution is added to the aqueous solution a to form an aqueous solution b, and while stirring, the dissolved metal components are coprecipitated by the neutralization reaction to form a metal composite hydroxide. The alkaline solution used here is preferably dropped in an amount sufficient for the aqueous solution b to maintain pH 10-14. As such an alkaline solution, for example, an aqueous solution of sodium hydroxide, potassium hydroxide, sodium carbonate, ammonia or the like can be used, and among them, sodium hydroxide, sodium carbonate or a mixed solution thereof is preferably used.

The temperature of the aqueous solution b during the neutralization reaction is preferably 30 ° C. or higher, and more preferably 30 to 60 ° C. Moreover, 30 minutes-120 minutes are preferable, and, as for the stirring time of the aqueous solution b, 30 to 60 minutes are more preferable.
After stirring, the metal composite hydroxide may be recovered by filtering the aqueous solution b. The recovered metal composite hydroxide is preferably washed with water and then dried.

  Next, the recovered metal composite hydroxide and the lithium compound may be dry-mixed to obtain a desired lithium composite oxide composition, and the obtained mixed powder may be fired under an oxygen atmosphere. As a lithium compound used here, lithium hydroxide or its hydrate, lithium peroxide, lithium nitrate, lithium carbonate etc. are mentioned, for example. In dry mixing of the metal composite hydroxide and the lithium compound, a common dry mixer or mixing granulator such as a ball mill or a V blender can be used, and it is more preferable to use a planetary ball mill capable of self-revolution.

The firing of the mixed powder is preferably performed in two stages (temporary firing and main firing). By performing the two-step firing, in the temporary firing, after the thermal decomposition components such as water molecules and carbon dioxide from the hydroxides and carbonates in the mixed powder are removed, the main firing is performed, which is efficient Lithium composite oxide secondary particles (A) can be obtained. The conditions for the pre-sintering are not particularly limited, but the temperature raising rate is preferably from room temperature to 1 to 20 ° C./minute. The firing atmosphere is preferably an air atmosphere or an oxygen atmosphere. The firing temperature is preferably 700 ° C. to 1000 ° C., and more preferably 650 ° C. to 750 ° C. Furthermore, the baking time is preferably 3 to 20 hours, and more preferably 4 to 6 hours.
After the obtained calcined product is crushed in a mortar or the like, an appropriate amount of a binder is mixed and granulated, and it is preferable to perform main baking. The fired product obtained after the main firing is a lithium composite oxide secondary particle (A).

The conditions for the main firing are not particularly limited, but it is preferable that the temperature rising rate is again from room temperature to a temperature rising rate of 1 to 20 ° C./minute. The firing atmosphere is preferably an air atmosphere or an oxygen atmosphere. The firing temperature is 700 ° C. to 1200 ° C. from the viewpoint of controlling the average particle diameter of the primary particles of the lithium composite oxide constituting the lithium composite oxide secondary particles (A) obtained after the main firing to a desired value. The temperature is preferably 700 to 1000 ° C., and more preferably 750 to 900 ° C. Furthermore, the baking time is preferably 3 to 20 hours, and more preferably 8 to 10 hours.
For such two-stage firing, an electric furnace, a rotary kiln, a tubular furnace, a pusher furnace, and the like in which the oxygen concentration in the gas atmosphere is adjusted to 20 mass% or more, such as an oxygen atmosphere or a dry air atmosphere subjected to dehumidification and decarbonization. Etc. can be used.

  The average particle diameter of the primary particles of the lithium composite oxide represented by the above formula (I) is preferably 500 nm or less, more preferably 300 nm or less. The lower limit of the average particle diameter of the primary particles is not particularly limited, but is preferably 50 nm or more from the viewpoint of handling.

The average particle diameter of the lithium composite oxide secondary particles (A) obtained is preferably 25 μm or less, more preferably 20 μm or less. The lower limit of the average particle diameter of the secondary particles is not particularly limited, but is preferably 1 μm or more, more preferably 5 μm or more from the viewpoint of handling.
In addition, in this specification, the average particle diameter of particle | grains means the average value of the particle diameter (length of a long axis) of dozens of particle | grains measured in observation by the electron microscope of SEM or TEM.

Alternatively, in order to obtain the lithium composite oxide secondary particles (A) represented by the above formula (II), the mixed powder containing the lithium compound, the nickel compound, the cobalt compound, and the aluminum compound is fired. Specifically, an aqueous solution a ′ may be obtained by first dissolving a nickel compound, a cobalt compound, and an aluminum compound in water so as to obtain a desired lithium composite oxide composition. Examples of such nickel compounds, cobalt compounds and aluminum compounds include sulfates, nitrates, carbonates, acetates, oxalates, oxides, hydroxides, halides and the like of these metal elements. Specific examples thereof include, but are not limited to, nickel sulfate, cobalt sulfate, aluminum sulfate, nickel acetate, cobalt acetate, aluminum acetate and the like.
In this process, Mg, Ti, Nb, Fe, Cr, as a metal (M ² ) element which substitutes a part of the lithium metal composite oxide so as to obtain the composition of the desired composite oxide as needed. One or two or more elements selected from Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi and Ge may be mixed.

  Next, an alkaline solution is added to the aqueous solution a 'to form an aqueous solution b', and while stirring, the dissolved metal components are coprecipitated by the neutralization reaction to form a metal composite hydroxide. The alkali solution used here is preferably added dropwise in an amount sufficient for the aqueous solution b 'to maintain a pH of 10-14. As such an alkaline solution, for example, an aqueous solution of sodium hydroxide, potassium hydroxide, sodium carbonate, ammonia or the like can be used, and among them, ammonia, sodium hydroxide, sodium carbonate or a mixed solution thereof is preferably used.

40 degreeC or more is preferable, and, as for the temperature of aqueous solution b 'in the said neutralization reaction, more preferably, it is 40 degreeC-60 degreeC. Moreover, 30 to 120 minutes are preferable and, as for the stirring time of aqueous solution b ', 30 to 60 minutes are more preferable.
An oxidizing agent such as sodium hypochlorite or hydrogen peroxide solution is further added to the aqueous solution b ′ after the neutralization reaction from the viewpoint of forming a metal composite hydroxide having a high bulk density to obtain a useful positive electrode active material. You may

After stirring, the metal composite hydroxide may be recovered by filtering the aqueous solution b ′. The recovered metal composite hydroxide is preferably calcined to form a metal composite oxide from the viewpoint of stabilizing the quality of the obtained lithium composite oxide and from the viewpoint of reacting uniformly and sufficiently with lithium.
The firing conditions for obtaining the metal composite oxide from the metal composite hydroxide are not particularly limited. For example, the firing temperature is preferably 500 ° C. to 1100 ° C., more preferably 600 to 900 ° C. in the air atmosphere. And it is sufficient.

  Next, the metal composite oxide obtained by the above-mentioned baking and the lithium compound may be dry-mixed so as to obtain a desired lithium composite oxide composition, and the obtained mixed powder may be fired under an oxygen atmosphere. As a lithium compound used here, lithium hydroxide or its hydrate, lithium peroxide, lithium nitrate, lithium carbonate etc. are mentioned, for example. In dry mixing of the metal composite oxide and the lithium compound, a common dry mixer or mixing granulator such as a ball mill or a V blender can be used. For firing, an electric furnace, a rotary kiln, a tubular furnace, a pusher furnace, etc. in which the oxygen concentration in the gas atmosphere is adjusted to 20 mass% or more, such as an oxygen atmosphere, a dry air atmosphere subjected to dehumidification and decarbonation treatment, etc. It can be used.

  The firing conditions of the above-mentioned mixed powder include a viewpoint of avoiding that the crystals of the lithium composite oxide obtained are not developed and become structurally unstable, and the layered structure of the lithium composite oxide is collapsed to obtain lithium ions. The firing temperature is preferably 650 ° C. to 850 ° C., and more preferably 700 ° C. to 800 ° C. from the viewpoint of avoiding difficulty in insertion and detachment. The firing time is preferably 5 to 20 hours, and more preferably 6 to 10 hours.

  The firing of the mixed powder is preferably performed in two stages (temporary firing and main firing). By performing the two-step firing, in the temporary firing, after the thermal decomposition components such as water molecules and carbon dioxide from the hydroxides and carbonates in the mixed powder are removed, the main firing is performed, which is efficient Lithium composite oxide secondary particles (A) can be obtained. As conditions for temporary firing, it is preferable to set a firing temperature to 400 ° C. to 600 ° C., and to set the firing time to 1 hour or more, and after a fired product obtained by temporary firing is crushed in a mortar or the like, The granulated product thus obtained is subjected to main baking. As the conditions for the main firing, it is preferable to set a firing temperature to 650 ° C. to 850 ° C. and to set the firing time to 5 hours or more.

Finally, the calcined product obtained by the main calcination is washed with water, filtered and dried to obtain lithium composite oxide secondary particles (A). The slurry concentration when washing the calcined product obtained by this calcination with water is preferably 200 to 4000 g / L from the viewpoint of preventing the lithium from being detached from the obtained lithium composite oxide secondary particles (A). And 500 to 2000 g / L are more preferable.
In addition, the electric conductivity of water used when washing with water is 10 μS from the viewpoint of avoiding precipitation of lithium carbonate on the lithium composite oxide secondary particles (A) by containing a large amount of carbon dioxide gas in the water. It is preferably less than 1 / cm, more preferably 1 μS / cm or less.
Furthermore, drying may be performed in two stages. The drying in the first step is performed at 90 ° C. or less until the water content in the lithium composite oxide secondary particles (water content measured at a vaporization temperature of 300 ° C.) becomes 1 mass% or less. Thereafter, it is preferable to carry out the second stage drying at 120 ° C. or higher.

  In addition, the average particle diameter of the primary particle of lithium complex oxide represented by said Formula (II), and the average particle diameter of lithium complex oxide secondary particle (A) are respectively lithium represented by Formula (I) The average particle diameter of the primary particles of the composite oxide and the average particle diameter of the lithium composite oxide secondary particles (A) are the same.

The step (Y) provided in the method for producing a positive electrode active material composite for lithium ion secondary batteries of the present invention comprises subjecting a lithium compound, a metal compound containing at least an iron compound or a manganese compound and a phosphoric acid compound to a hydrothermal reaction. The slurry containing the lithium-based polyanion primary particles and carbon source obtained was spray-dried and granulated, and then calcined to adjust the porosity to 50 to 80% by volume, and carbon was supported on the surface. It is a process of obtaining the granule (C) which consists of lithium system polyanion particles (B). The lithium-based polyanion particles (B) having carbon supported on the surface, which form the granules (C) obtained in this step, have the following formula (III):
LiFe _m Mn _n M ³ _o PO ₄ (III)
(In the formula (III), M ³ represents Co, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. M, n, and o satisfy 0 ≦ m ≦ 1, 0 ≦ n ≦ 1, 0 ≦ o ≦ 0.3, and m + n ≠ 0 are satisfied, and 2m + 2n + (valence number of M ³ ) × o = 2 is satisfied.)
And is a particle having carbon supported on the surface, and is a particle having an olivine type structure constituting a positive electrode active material. A rigid body obtained by strongly aggregating lithium-based polyanion primary particles as in the conventional method by obtaining a highly porous granule (C) comprising such particles (B) by the step (Y). As compared with the use of secondary particles, in the step (Z) to be described later, the granulate (C) is easily disintegrated without applying an excessive load, and the secondary particles of lithium complex oxide can be obtained by the particles (B). The surface of the particles (A) can be well coated.

More specifically, the step (Y) includes the following (i) to (iv):
(I) mixing a phosphoric acid compound with a mixture (c-1) containing a lithium compound to obtain a complex (c-2),
(Ii) subjecting the obtained complex (c-2) and the slurry (c-3) containing at least an iron compound or a metal compound containing a manganese compound to a hydrothermal reaction to obtain a complex (c-4) Step of obtaining
(Iii) After preparing the obtained composite (c-4) and the slurry (c-5) containing the carbon source (d), the slurry (c-5) is spray-dried to obtain lithium-based polyanion particles and carbon Obtaining a preliminary granulated body (c-6) comprising the source (d), and (iv) calcining the obtained preliminary granulated body (c-6) in a reducing atmosphere or an inert atmosphere to It is preferable to include a step of obtaining a granulated body (C) composed of lithium-based polyanion particles (B) on which carbon is supported.

Said process (i) is a process of mixing a phosphoric acid compound with the mixture (c-1) containing a lithium compound, and obtaining complex (c-2).
Examples of lithium compounds that can be used include lithium hydroxide (eg, LiOH, LiOH · H ₂ O), lithium carbonate, lithium sulfate, and lithium acetate. Among them, lithium hydroxide is preferred.
The content of the lithium compound in the mixture (c-1) is preferably 5 to 50 parts by mass, and more preferably 7 to 45 parts by mass with respect to 100 parts by mass of water.

  It is preferable to stir the mixture (c-1) in advance before mixing the phosphoric acid compound with the mixture (c-1). The stirring time of the mixture (c-1) is preferably 1 to 15 minutes, more preferably 3 to 10 minutes. Moreover, the temperature of the mixture (c-1) is preferably 20 to 90 ° C., more preferably 20 to 70 ° C.

Examples of the phosphoric acid compound used in step (i) include orthophosphoric acid (H ₃ PO ₄ , phosphoric acid), metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, triphosphoric acid, tetraphosphoric acid, ammonium phosphate, ammonium hydrogen phosphate and the like. . Among them, it is preferable to use phosphoric acid, and it is preferable to use as a 70 to 90% by mass aqueous solution. When using phosphoric acid as a phosphoric acid compound, it is preferable to drip phosphoric acid, stirring a mixture (c-1). By adding phosphoric acid dropwise to the mixture (c-1) little by little, the reaction proceeds well in the mixture (c-1) and the complex (c-2) is dispersed uniformly in the slurry. While being generated, unnecessary aggregation of the complex (c-2) can be effectively suppressed.

The dropping rate of phosphoric acid to the above mixture (c-1) is preferably 15 to 50 mL / min, more preferably 20 to 45 mL / min, and still more preferably 28 to 40 mL / min. Moreover, the stirring time of the mixture (c-1) while dropping phosphoric acid is preferably 0.5 to 24 hours, more preferably 3 to 12 hours. Furthermore, the stirring speed of the mixture (c-1) while dropping phosphoric acid is preferably 200 to 700 rpm, more preferably 250 to 600 rpm, and still more preferably 300 to 500 rpm.
In addition, when stirring a mixture (c-1), it is preferable to cool to below the boiling point temperature of a mixture (c-1). Specifically, cooling to 80 ° C. or less is preferable, and cooling to 20 to 60 ° C. is more preferable.

  The mixture (c-1) after mixing the phosphoric acid compound preferably contains 2.7 to 3.3 moles of lithium, and 2.8 to 3.1 moles of lithium per mole of phosphoric acid. Is more preferred.

In addition, the reaction in the mixture is completed by purging nitrogen to the mixture (c-1) after the mixture of the phosphoric acid compound, and the complex (c) is a precursor of lithium-based polyanion particles (c -2) can be produced in the mixture. When nitrogen is purged, the reaction can be allowed to proceed with the concentration of dissolved oxygen in the mixture (c-1) reduced, and the dissolved oxygen in the mixture containing the complex (c-2) obtained Since the concentration is also effectively reduced, the oxidation of iron compounds, manganese compounds and the like added in the next step (ii) can be effectively suppressed. In the mixture containing the complex (c-2), the precursor of the lithium-based polyanion particle is present as a finely dispersed particle. Such complex (c-2) is obtained as trilithium phosphate (Li ₃ PO ₄ ).

The pressure at the time of purging nitrogen is preferably 0.1 to 0.2 MPa, more preferably 0.1 to 0.15 MPa. Moreover, the temperature of the mixture (c-1) after mixing a phosphoric acid compound becomes like this. Preferably it is 20-80 degreeC, More preferably, it is 20-60 degreeC. The reaction time is preferably 5 to 60 minutes, more preferably 15 to 45 minutes.
Moreover, when purging nitrogen, it is preferable to stir the mixture (c-1) after mixing a phosphoric acid compound from a viewpoint of making reaction advance favorably. The stirring speed at this time is preferably 200 to 700 rpm, more preferably 250 to 600 rpm.

  Further, from the viewpoint of more effectively suppressing the oxidation of the dispersed particles on the surface of the dispersed particles of the complex (c-2) and achieving the finer dispersed particles, it is dissolved in the mixture (c-1) after the phosphoric acid compound is mixed. The oxygen concentration is preferably 0.5 mg / L or less, more preferably 0.2 mg / L or less.

  In the step (ii), the slurry (c-3) containing the complex (c-2) obtained in the step (i) and the metal salt containing at least an iron compound or a manganese compound is subjected to a hydrothermal reaction It is a process of obtaining complex (c-4). The complex (c-2) obtained in the above step (i) is used as a mixture as a precursor of lithium-based polyanion particles (B), to which a metal compound containing at least an iron compound or a manganese compound is added It is preferable to use as a slurry (c-3). Thereby, the target lithium-based polyanion particles (B) for forming the granules (C) can be obtained as extremely fine particles while simplifying the process.

  Iron compounds which can be used include iron acetate, iron nitrate, iron sulfate and the like. These may be used singly or in combination of two or more. Among these, iron sulfate is preferable from the viewpoint of enhancing the battery characteristics of the lithium-based polyanion particles (B).

  As a manganese compound which can be used, manganese acetate, manganese nitrate, manganese sulfate etc. are mentioned. These may be used singly or in combination of two or more. Among them, manganese sulfate is preferable from the viewpoint of enhancing the battery characteristics of the lithium-based polyanion particles (B).

When both an iron compound and a manganese compound are used as the metal compound, the molar ratio of the manganese compound and the iron compound (manganese compound: iron compound) is preferably 99: 1 to 1:99, more preferably 90 10 to 10:90. Moreover, the total addition amount of these iron compounds and manganese compounds is preferably 0.99 to 1.01 mol, more preferably 1 mol to 1 mol of Li ₃ PO ₄ contained in the slurry (c-3). It is 0.995 to 1.005 mol.

Furthermore, if necessary, metal (M ³ ) compounds other than iron compounds and manganese compounds may be used as the metal compound. As such a metal (M ³ ) compound, a sulfate, a halogen compound, an organic acid salt, a hydrate of these, and the like can be used. These may be used singly or in combination of two or more. Among these, from the viewpoint of enhancing the battery characteristics, it is more preferable to use a sulfate.
When using these metal (M ³ ) compounds, the total addition amount of the iron compound, the manganese compound and the metal (M ³ ) compound is the phosphoric acid in the complex (c-2) obtained in the above step (i) The amount is preferably 0.99 to 1.01 mol, and more preferably 0.995 to 1.005 mol, per 1 mol.

  The amount of water used in the hydrothermal reaction is the phosphate ion contained in the slurry (c-3) from the viewpoint of solubility of the metal compound used, ease of stirring, and efficiency of synthesis, etc. Preferably it is 10-30 mol with respect to 1 mol, More preferably, it is 12.5-25 mol.

In the step (ii), the addition order of the iron compound, the manganese compound and the metal (M ³ ) compound is not particularly limited. Moreover, while adding these metal compounds, you may add antioxidant as needed. As such an antioxidant, sodium sulfite (Na ₂ SO ₃ ), sodium hydrosulfite (Na ₂ S ₂ O ₄ ), aqueous ammonia and the like can be used. From the viewpoint of preventing the formation of lithium-based polyanion particles (B) from being suppressed by adding an excessive amount of the antioxidant, the amount of the iron compound, the manganese compound, and the metal (M ³ used if necessary) Preferably it is 0.01-1 mol with respect to a total of 1 mol of compounds), More preferably, it is 0.03-0.5 mol.

The content of the complex (c-4) in the slurry (c-3) obtained by adding an iron compound, a manganese compound and, if necessary, a metal (M ³ ) compound and an antioxidant is preferably It is 10 to 50% by mass, more preferably 15 to 45% by mass, and still more preferably 20 to 40% by mass.

The hydrothermal reaction in the step (ii) may be 100 ° C. or higher, preferably 130 to 180 ° C. The hydrothermal reaction is preferably carried out in a pressure vessel, and when the reaction is carried out at 130 to 180 ° C., the pressure at this time is preferably 0.3 to 0.9 MPa, and the reaction is carried out at 140 to 160 ° C. Is preferably 0.3 to 0.6 MPa. The hydrothermal reaction time is preferably 0.1 to 48 hours, and more preferably 0.2 to 24 hours.
The obtained complex (c-4) is filtered, washed with water, and filtered again to recover a cake having a water content of 10 to 50% by mass. In addition, although vacuum filtration, pressure filtration, centrifugal filtration etc. can be used for a filtration means, pressure filtration, such as a filter press, is preferable from the easiness of operation etc.

  The amount of washing water used for washing is 10 parts by mass or more, preferably 12 parts by mass or more, with respect to 1 part by mass of the complex (c-4) in the filtration residue.

The BET specific surface area of the complex (c-4) obtained by drying the above cake is preferably 5 to 40 m ² / g, more preferably 5 to 20 m, from the viewpoint of effectively reducing the amount of adsorbed water. ^{It is 2} / g. When the BET specific surface area of the complex (c-4) is less than 5 m ² / g, the lithium-based polyanion particles (B) may be enlarged. When the BET specific surface area exceeds 40 m ² / g, the amount of adsorbed water of the positive electrode active material for a secondary battery may increase to affect the battery characteristics.

Further, the average particle diameter of the composite (c-4) is such that the obtained lithium-based polyanion particles (B) are complexed with the lithium composite oxide secondary particles (A) to satisfactorily cover the surface, and the durability etc. From the viewpoint of obtaining an excellent positive electrode active material complex for a lithium ion secondary battery, the thickness is preferably 50 to 300 nm, and more preferably 75 to 250 nm.
Here, the average particle diameter of the composite (c-4) means an average value of values obtained by the same measurement as the average particle diameter of the particles.

  In the above step (iii), the slurry (c-5) is spray-dried after the slurry (c-5) containing the complex (c-4) obtained in the step (ii) and the carbon source (d) is prepared. It is a process of obtaining the pre-granulate (c-6) which consists of lithium type polyanion particle | grains and a carbon source (d).

  The carbon source (d) constituting the preliminary granulated body (c-6) is a raw material to be carbon supported on the surface of the lithium-based polyanion particles (B) as carbon derived from the carbon source (d). As such a carbon source (d), cellulose nanofibers (d1) or a water-soluble carbon material (d2) can be mentioned. The above-mentioned cellulose nanofiber (hereinafter also referred to as "CNF"), which is a carbon source (d), is a skeletal component that occupies about 50% of all plant cell walls, and the plant fibers constituting such cell walls are nanosized It is a lightweight high-strength fiber which can be obtained by disentanglement etc., and carbon derived from cellulose nanofiber (d1) has a periodic structure. The fiber diameter of such cellulose nanofibers is 1 nm to 100 nm, and also has good dispersibility in water. Moreover, in the cellulose molecular chain which comprises a cellulose nanofiber, since the periodic structure by carbon is formed, this is combined with the said lithium-type polyanion particle (B), being carbonized by passing through a later process By being firmly supported on the surface of the particles, good electron conductivity can be imparted.

  The water-soluble carbon material (d2) as the carbon source (d) is a carbon material which dissolves in 100 g of water at 25 ° C. 0.4 g or more, preferably 1.0 g or more, in carbon atom equivalent amount of the water-soluble carbon material By being carbonized, it is present as carbon on the surface of the lithium-based polyanion particles (B). Examples of such a water-soluble carbon material include one or more selected from saccharides, polyols, polyethers, and organic acids. More specifically, for example, monosaccharides such as glucose, fructose, galactose and mannose; disaccharides such as maltose, sucrose and cellobiose; polysaccharides such as starch and dextrin; ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, butane And polyols and polyethers such as diol, propanediol, polyvinyl alcohol and glycerin; and organic acids such as citric acid, tartaric acid and ascorbic acid. Among them, glucose, fructose, sucrose and dextrin are preferable, and glucose is more preferable, from the viewpoint of enhancing the solubility in a solvent and the dispersibility to effectively function as a carbon material.

  The carbon equivalent derived from the cellulose nanofiber (d1) or the carbon derived from the water-soluble carbon material (d2), which is present as carbon on the surface of the lithium-based polyanion particle (B) (carried amount of carbon) is lithium It can be confirmed as the amount of carbon measured using a carbon / sulfur analyzer on the system polyanion particles (B).

  The content of the complex (c-4) in the slurry (c-5) is preferably 10 to 30 parts by mass, and more preferably 15 to 30 parts by mass with respect to 100 parts by mass of water. A cake containing the above complex (c-4) may be used to achieve such content.

  When supporting carbon derived from the above-mentioned cellulose nanofibers (d1) on the surface of lithium-based polyanion particles (B) through the subsequent steps, the content of cellulose nanofibers (d1) in the slurry (c-5) The amount is such that the carbon atom equivalent amount is 0.3 to 6% by mass with respect to the total amount 100% by mass of the lithium-based polyanion particle (B) and the carbon supported on the particle surface desirable. Specifically, for example, the amount is preferably 0.1 to 20 parts by mass, and more preferably 1 to 10 parts by mass with respect to 100 parts by mass of water in the slurry (c-5).

  When supporting carbon derived from the water-soluble carbon material (d2) on the surface of the lithium-based polyanion particles (B) through the subsequent steps, the water-soluble carbon material (d2) in the slurry (c-5) The content is such that the carbon atom equivalent amount is 0.3 to 6% by mass with respect to 100% by mass of the total amount of carbon supported on the surface of the lithium-based polyanion particles (B) and such particles. Is desirable. Specifically, for example, the amount is preferably 0.1 to 18 parts by mass, and more preferably 1 to 10 parts by mass with respect to 100 parts by mass of water in the slurry (c-5).

  The slurry (c-5) contains a lithium-based polyanion particle (B) and a carbon source (d), that is, a lithium-based polyanion particle (B) and a cellulose nanofiber (d1), or a lithium-based polyanion particle (B) and water-soluble It is preferable to perform the process using a dispersing machine (homogenizer) from a viewpoint of disperse | distributing a carbon material (d2) uniformly. As such a dispersing machine, for example, a disintegrator, a beater, a low pressure homogenizer, a high pressure homogenizer, a grinder, a cutter mill, a ball mill, a jet mill, a short screw extruder, a twin screw extruder, an ultrasonic stirrer, a domestic juicer mixer, etc. It can be mentioned. Among them, an ultrasonic stirrer is preferable from the viewpoint of dispersion efficiency. The degree of dispersion uniformity of the slurry (c-5) can also be quantitatively evaluated by, for example, light transmittance using a UV / visible light spectrometer or viscosity using an E-type viscometer, and visual observation It can also be simply evaluated by confirming that the white turbidity is uniform by. The treatment time with the disperser is preferably 1 to 30 minutes, more preferably 2 to 15 minutes. The slurry (c-5) thus treated can be maintained in good mixing for several days, so it can be prepared and stored in advance.

  When the cellulose nanofiber (d1) is used as the carbon source (d), the slurry (c-5) is preferably further classified by wet from the viewpoint of effectively removing the cellulose nanofiber which is still in the aggregated state. For wet classification, a sieve or a commercially available wet classifier can be used. Although the mesh size of the sieve may vary depending on the fiber length of the cellulose nanofibers used, it is preferably about 150 μm from the viewpoint of working efficiency.

  Accordingly, the solid content concentration of the slurry (c-5) used to undergo the next step (iii) is preferably 9 to 35% by mass, and more preferably 13 to 30% by mass.

  Next, in the step (iii), the obtained slurry (c-5) is spray-dried to obtain a pre-granulate (c-6). The pre-granulated body (c-6) becomes a granulated body (C) formed of lithium-based polyanion particles (B) having carbon supported on the surface through the subsequent steps. This avoids using robust secondary particles formed by tightly aggregating lithium-based polyanion primary particles, and uses the granulate (C) that can be easily disintegrated without applying excessive load. The surface of the lithium composite oxide secondary particles (A) is favorably coated with lithium-based polyanion particles (B) having carbon supported on the surface, which constitute the granulated body (C). Make it possible.

  110-160 degreeC is preferable and, as for the hot air temperature in the case of spray-drying, 120-140 degreeC is more preferable. The ratio G / S of the supply amount G (L / min) of the hot air and the supply amount S (L / min) of the slurry (c-5) is preferably 500 ≦ G / S ≦ 10000, and 1000 ≦ G / S. ≦ 9000 is more preferred.

The particle size of the pre-granulate (c-6) obtained in step (iii) is preferably 5 to 14 μm, more preferably 5 to 12 μm, as the D ₅₀ value in the particle size distribution based on laser diffraction / scattering method. It is.
Here, the D ₅₀ value in the particle size distribution measurement is a value obtained by the volume-based particle size distribution based on the laser diffraction / scattering method, and the D ₅₀ value means the particle size (median diameter) at 50% of accumulation. .

  In the step (iv), the preliminary granulated body (c-6) obtained in the step (iii) is fired in a reducing atmosphere or an inert atmosphere to carry lithium-based polyanion particles (B In the step of obtaining a granulated body (C) consisting of Granules (C) having appropriate disintegratability while causing carbon to be more firmly supported on the surface of lithium-based polyanion particles (B) constituting the granules (C) by passing through the step (iv) Can be formed.

  The firing temperature is preferably 600 to 800 ° C., more preferably 700 to 800 ° C., from the viewpoint of effectively carbonizing the carbon source (d) and from the viewpoint of imparting appropriate disintegrability to the granulated body (C). It is. The baking time is preferably 30 minutes to 3 hours, more preferably 1 hour to 2 hours.

  The porosity of the granules (C) consisting of lithium-based polyanion particles (B) having carbon supported on the surface is 45 to 80% by volume, preferably 50 to 80, in terms of the porosity based on the mercury intrusion method. It is volume%.

Moreover, the tap density of the granulated body (C) consisting of lithium-based polyanion particles (B) having carbon supported on the surface thereof is preferably less than 1.0 g / cm ³ , and more preferably 0.6 to 0. It is 9 g / cm ³ .

Furthermore, the average particle diameter of the granulated body (C) consisting of lithium-based polyanion particles (B) having carbon supported on the surface is preferably 5 to 15 μm as D ₅₀ value in particle size distribution based on laser diffraction / scattering method. More preferably, it is 5-12 micrometers.

The disintegration strength of the granulated body (C) consisting of lithium-based polyanion particles (B) having carbon supported on the surface thereof is preferably 1.8 KN / mm or less, more preferably 1.75 KN / mm or less. The disintegration strength refers to the ease of disintegration by compression of the granule (C) consisting of lithium-based polyanion particles (B) having carbon supported on the surface, and means a value determined by the following formula (1) Do.
Collapse strength (KN / mm) = 10 / (t ₀ −t ₁₀ ) of granulated body (C) (1)
In t ₀ in the formula (1), 3 g of a granule (C) consisting of lithium-based polyanion particles (B) having carbon supported on the surface thereof is introduced into a cylindrical container having a diameter of 20 mm, and falling from a height of 1 cm Shows the layer thickness (mm) of the granulated body (C) in the densely packed state after repeating tapping 10 times, and t ₁₀ indicates a load of 10 KN from the top to the closely packed granular body (C) The layer thickness (mm) of the granulated body (C) at the time of being applied is shown.

  Step (Z) of the method for producing a positive electrode active material composite for a lithium ion secondary battery of the present invention comprises the lithium composite oxide secondary particles (A) obtained in step (X) and step (Y) The obtained granulated body (C) is mixed while applying a compressive force and a shearing force to disintegrate the granulated body (C), and the lithium composite oxide secondary particles (A) and carbon on the surface Is a step of complexing with the supported lithium-based polyanion particles (B). By passing through the above steps, fine lithium-based polyanion particles (B) formed by the collapse of the granules (C) are densely and extensively covered on the surface of the lithium composite oxide secondary particles (A). A positive electrode active material complex for a lithium ion secondary battery can be obtained.

  In the step (Z), the mixture of the lithium composite oxide secondary particles (A) and the granules (C) obtained previously is sufficiently dry mixed before being mixed while applying compressive force and shear force. It is preferable to do. The dry mixing method is preferably mixing using a common dry mixer such as a ball mill or V blender, and more preferably mixing using a planetary ball mill capable of self-revolution.

  The process of mixing while applying a compressive force and a shear force (hereinafter also referred to as "combining") may be performed in a closed vessel equipped with an impeller, a rotor tool, and the like. As an apparatus equipped with such a closed container, a high speed shear mill, a blade type kneader, a high speed mixer, etc. may be mentioned. Specifically, for example, particle design apparatus COMPOSI, mechano hybrid, high performance flow mixer FM mixer (Japan Coke Industry Co., Ltd. Fine particle complexing device Mechanofusion, Nobilta (manufactured by Hosokawa Micron Corporation), surface reforming device Miraro, Hybridization system (manufactured by Nara Machinery Co., Ltd.), Eirich Intensiv Mixer (manufactured by Nippon Eirich Co., Ltd.) are suitably used. be able to. As processing conditions to be complexed, the temperature is preferably 5 to 80 ° C., more preferably 10 to 50 ° C. The atmosphere is not particularly limited, but is preferably an inert gas atmosphere or a reducing gas atmosphere.

More specifically, for example, when Nobilta (manufactured by Hosokawa Micron Corporation), which is a dry particle composite apparatus equipped with an impeller, is used as a composite apparatus, the number of revolutions of the impeller is the above-mentioned granulated body (C) From the viewpoint of obtaining a composite oxide in which lithium-based polyanion particles (B) are favorably coated on the surface of the lithium composite oxide secondary particles (A) while efficiently disintegrating Preferably it is 2000-4000 rpm. Further, the time for complexing is preferably 1 to 10 minutes, more preferably 1 to 7 minutes.
Moreover, when using Erich intensive mixer (made by Nippon Erich Co., Ltd.), which is a high-speed stirring mixer equipped with a rotor tool, as an apparatus for performing such compounding, the number of revolutions of the rotor tool is preferably 2000 to 8000 rpm. More preferably 2000 to 6000 rpm. Further, the time for complexing is preferably 1 to 10 minutes, more preferably 1 to 7 minutes.

The time of complexation and / or the number of revolutions of the impeller or the like in the step (Z) depends on the amount of the mixture of the lithium composite oxide secondary particles (A) and the granules (C) charged into the closed vessel. It is necessary to make appropriate adjustments. And, by operating the closed vessel, while the compressive force and the shear force are applied to the mixture between the impeller etc. and the inner wall of the closed vessel, the lithium complex oxide is favorably broken while the granulated body (C) is favorably collapsed. It becomes possible to carry out a treatment of complexing the secondary particles (A) and the lithium-based polyanion particles (B) having carbon supported on the surface, and on the surface of the lithium composite oxide secondary particles (A), A positive electrode active material complex for a lithium ion secondary battery can be obtained, in which the lithium-based polyanion particles (B) in which carbon is supported on the surface are favorably complexed and coated.
For example, when the compounding is performed for 1 to 8 minutes in a closed container provided with an impeller rotating at 2000 to 5000 rpm, the amount of the mixture introduced into the closed container is an effective container (of the closed containers provided with an impeller). The amount is preferably 0.1 to 0.7 g, more preferably 0.15 to 0.4 g, per 1 cm ^{3 of} a container corresponding to a portion capable of containing the above mixture.

  The mass ratio (particles (A): particles (B)) of the lithium composite oxide secondary particles (A) to be complexed in the step (Z) and the lithium-based polyanion particles (B) having carbon supported on the surface is It is preferably 95: 5 to 60:40, more preferably 92: 8 to 65:35 from the viewpoint of allowing the surface of the lithium composite oxide secondary particles (A) to be coated well with the lithium-based polyanion particles (B). More preferably, it is 90: 10-70: 30. The amount of the granules (C) in the mixture may be adjusted so as to be such an amount.

The extent to which the lithium-based polyanion particles (B) having carbon supported on the surface thereof are complexed and coated on the surface of the lithium composite oxide secondary particles (A) is X-ray photoelectron spectroscopy ( Peak intensity ratio by (XPS) ((peak intensity of Ni ₂ p _3/2 ) / (peak intensity of P ₂ p + peak intensity of C 1s)), ie, the peak of Ni ₂ p _3/2 released from lithium composite oxide secondary particles (A) The intensity can be confirmed by the value of the ratio of the peak intensities of P2p and C1s released from the lithium-based polyanion particles (B) having carbon supported on the surface. Specifically, when the obtained positive electrode active material complex for a lithium ion secondary battery is irradiated with soft X-rays of several keV, the site irradiated with such soft X-rays is unique to the element constituting the site. Since photoelectrons having energy values of are emitted, peak intensities corresponding to trivalent Ni obtained by analyzing the peaks of Ni.sub.2p _3/2 released from the lithium composite oxide secondary particles (A), and the surface The material which is the surface of the positive electrode active material complex for lithium ion secondary batteries by comparing the sum of the peak intensities of P2p and C1s released from the lithium-based polyanion particles (B) on which carbon is supported. In other words, the lithium-based polyanion particles (B) having carbon supported on such a surface can cover the lithium composite oxide secondary particles (A).

More specifically, the positive electrode active material composite for a lithium ion secondary battery manufactured according to the present invention has such a peak intensity ratio by XPS from the viewpoint of securing excellent discharge characteristics and safety in the obtained secondary battery. ((Peak intensity of Ni ₂ p _3/2 ) / (peak intensity of P ₂ p + peak intensity of C 1 s)) is usually 0.05 or less, preferably 0.04 or less, more preferably 0.03 or less .

  Furthermore, regarding the peak intensity ratio by the above-mentioned XPS, by comparing the XPS peak intensity ratio before and after applying a predetermined shear force to the obtained positive electrode active material composite for lithium ion secondary battery, the secondary lithium complex oxide The coating strength of lithium-based polyanion particles (B) on the surface of particles (A) can be evaluated.

Specifically, 2 g of the obtained positive electrode active material complex for lithium ion secondary battery and 10 g of N-methyl-2-pyrrolidone are stirred and kneaded at 2000 rpm for 3 minutes using a high-speed mixer (filmix 40 L type manufactured by PRIMIX Corporation) The obtained slurry was subjected to warm air drying to obtain a positive electrode active material complex for a lithium ion secondary battery, and the peak intensity ratio by the XPS ((peak intensity of Ni2p _3/2 ) / (p After determining the P2p peak intensity + C1s peak intensity)), the ratio to the above-mentioned XPS peak intensity ratio before applying shear force ((peak intensity ratio after applying shear force) / (before applying shear force) Peak intensity ratio)) (hereinafter this ratio is referred to as "covering intensity"). The smaller the value of this coating strength is, the closer to 1 the stronger the lithium complex oxide secondary particles are covered with lithium-based polyanion particles.

  As a lithium ion secondary battery to which the positive electrode for secondary batteries including the positive electrode active material composite for lithium ion secondary batteries manufactured according to the present invention can be applied, the positive electrode, the negative electrode, the electrolyte and the separator are essential components It is not particularly limited as long as

  The positive electrode of a lithium ion secondary battery can be prepared by using a positive electrode active material complex for a lithium ion secondary battery according to the present invention, a conductive agent such as carbon black, and a binder (binder) such as polyvinylidene fluoride. A solvent such as 2-pyrrolidone is added, and the mixture is sufficiently kneaded to obtain a positive electrode slurry, which is then coated on a current collector such as an aluminum foil and then consolidated by a roller press or the like and dried.

  The negative electrode of the lithium ion secondary battery is not particularly limited by its material configuration as long as lithium ions can be stored during charging and released during discharging, and known materials can be used. . For example, it is a carbon material such as lithium metal, graphite or amorphous carbon. It is preferable to use an electrode formed of an intercalated material capable of electrochemically absorbing and desorbing lithium ions, particularly a carbon material.

  The electrolytic solution is one in which a supporting salt is dissolved in an organic solvent. The organic solvent is not particularly limited as long as it is an organic solvent generally used for an electrolyte solution of a lithium ion secondary battery, and, for example, carbonates, halogenated hydrocarbons, ethers, ketones, nitriles, lactones And oxolane compounds can be used.

The type of the supporting salt is not particularly limited, and an inorganic salt selected from LiPF ₆ , LiBF ₄ , LiClO ₄ and LiAsF ₆ , a derivative of the inorganic salt, LiSO ₃ CF ₃ , LiC (SO ₃ CF ₃ ) ₂ and _{LiN (SO 3 CF 3) 2} , LiN (SO 2 C 2 F 5) 2 and an organic salt selected from _{LiN (SO 2 CF 3) (} SO 2 C 4 F 9) and derivatives of the organic salts, It is preferable that it is at least one of

  The separator serves to electrically insulate the positive electrode and the negative electrode and to hold the electrolytic solution. For example, a porous synthetic resin film, in particular, a porous film of a polyolefin polymer (polyethylene, polypropylene) may be used.

The solid electrolyte electrically insulates the positive electrode and the negative electrode and exhibits high lithium ion conductivity. For example, La _0.51 Li _0.34 TiO _2.94 , Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ , Li ₇ La ₃ Zr ₂ O ₁₂ , 50Li ₄ SiO ₄ .50Li ₃ BO ₃ , Li _2.9 PO _3.3 N _0.46 , Li _3.6 Si _0.6 P _0.4 O ₄ , Li _1.07 Al _0.69 Ti _1.46 (PO ₄ ) ₃ , Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ , Li ₁₀ GeP ₂ S ₁₂ , Li _3.25 Ge _0.25 P _0.75 S ₄ , 30Li ₂ S · 26 B ₂ S ₃ · 44 Li I, 63 Li ₂ S · 36 Si S ₂ · 1 Li ₃ PO ₄ , 57 Li ₂ S · 38 Si S ₂ · 5 Li ₄ SiO ₄ , 70 Li ₂ S · 30 P ₂ S ₅ , 50 Li ₂ S · 50 GeS ₂ , Li ₇ P ₃ S ₁₁ and Li _3.25 P _0.95 S ₄ may be used.

  The shape of the lithium ion secondary battery having the above-mentioned configuration is not particularly limited, and may be various shapes such as coin, cylinder, square, and irregular shapes enclosed in a laminate outer package. .

  EXAMPLES Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[Production example 1: Production of lithium composite oxide secondary particles (A)]
After mixing 263 g of nickel sulfate hexahydrate, 281 g of cobalt sulfate heptahydrate, 241 g of manganese sulfate pentahydrate, and 3 L of water so that the molar ratio of Ni: Co: Mn is 1: 1: 1 To the mixed solution, 25% ammonia water was dropped at a dropping rate of 300 ml / min to obtain a slurry x1 containing a metal composite hydroxide having a pH of 11.
Next, the slurry x1 was filtered and dried to obtain a mixture x2 of metal composite hydroxides, and then 37 g of lithium carbonate was mixed with the mixture x2 in a ball mill to obtain a powder mixture x3.
The obtained powder mixture x 3 was calcined after being calcined at 800 ° C. for 5 hours in the air atmosphere to be granulated, and then granulated as main firing, and then calcined at 800 ° C. for 10 hours in the air atmosphere. Next particles (A) (LiNi _0.33 Co _0.33 Mn _0.34 O ₂ , average particle diameter 10 μm) were obtained.

Production Example 2 Production of Granulated Body (C-1) Composed of Lithium-Based Polyanion Particle (B-1) with CNF-Derived Carbon Supported on the Surface]
4071 g of LiOH.H ₂ O and 9.657 L of water were mixed to obtain a slurry b1. Next, 4204 g of a 75% aqueous phosphoric acid solution was added dropwise at 40 mL / min while stirring the obtained slurry b1 for 3 minutes while maintaining the temperature at 25 ° C. to obtain a slurry b2 containing Li ₃ PO ₄ .
The obtained slurry b2 was purged with nitrogen to make the dissolved oxygen concentration of the slurry b2 0.1 mg / L, and then 3807 g of MnSO ₄ · 5 H ₂ O and 2684 g of FeSO ₄ · 7 H ₂ O were added to the whole amount of the slurry b2 The slurry b3 was obtained. The molar ratio of added MnSO ₄ to FeSO ₄ (manganese compound: iron compound) was 70:30.
Next, the obtained slurry b3 was put into an autoclave and subjected to a hydrothermal reaction at 170 ° C. for 0.5 hours. The pressure in the autoclave was 0.8 MPa. After the hydrothermal reaction, the formed crystals were filtered and then washed with 12 parts by mass of water per 1 part by mass of the crystals. Thereafter, it was dewatered by a filter press device to obtain a dewatered cake b4.
The average particle size of the lithium-based polyanion particles in the dehydrated cake b4 was 100 nm.
8000 g of the dewatered cake b4 thus obtained was fractionated, and 1200 g of cellulose nanofibers (KY 100 G, manufactured by Daicel Finechem Co., Ltd.) and 8.5 L of water were added thereto to obtain a slurry b5 having a solid content concentration of 30 mass%. The obtained slurry b5 is dispersed for 10 minutes with an ultrasonic stirrer (T25, manufactured by IKA Co., Ltd.) to make the whole color uniformly, and then a spray dryer (MDL-050M, manufactured by Fujisaki Electric Co., Ltd.) is used. It spray-dried at the drying temperature of 130 degreeC, and obtained the pre-granulation body b6.
The obtained pre-granulated body b6 is calcined at 700 ° C. for 1 hour under an argon-hydrogen atmosphere (hydrogen concentration 3%), and phosphoric acid with 2.0 mass% of cellulose nanofiber-derived carbon supported on the surface Granulated body (C-1) consisting of manganese iron lithium secondary particles (B-1) (LiMn _0.7 Fe _0.3 PO ₄ , amount of carbon = 2.0% by mass, average particle diameter: 11 μm, porosity 51% by volume , Tap density 0.8 g / cm ³ ).

Production Example 3: Production of Granulated Body (C-2) Consisting of Lithium-Based Polyanion Particles (B-2) with CNF-Derived Carbon Supported on the Surface
The amount of water added to the dewatered cake b4 was changed to 12 L to obtain a slurry b5 having a solid content concentration of 25 mass%, and then the drying temperature in spray drying was changed to 140 ° C. Granulated body (C-2) (LiMn _0.7 Fe _0.3 PO ₄ ) composed of lithium manganese iron phosphate secondary particle (B-2) on the surface of which 2.0% by mass of cellulose nanofiber derived carbon is supported on the surface Amount of 2.0% by mass, average particle diameter: 8 μm, porosity 56% by volume, tap density 0.8 g / cm ³ ).

Production Example 4 Production of Granulated Body (C-3) Composed of Lithium-Based Polyanion Particle (B-3) with CNF-Derived Carbon Supported on Surface
The amount of water added to the dewatered cake b4 was changed to 17 L to obtain a slurry b5 having a solid content concentration of 20 mass%, and then the drying temperature in spray drying was changed to 150 ° C. Granulated body (C-3) (LiMn _0.7 Fe _0.3 PO ₄ ) composed of lithium manganese iron phosphate secondary particles (B-3) on the surface of which 2.0% by mass of carbon derived from cellulose nanofibers is supported on the surface the amount of = 2.0 weight%, average particle size: to give 8 [mu] m, porosity of 74 vol%, a tap density of 0.7g / cm ^3).

Production Example 5 Production of Granulated Body (C-4) Consisting of Lithium-Based Polyanion Particle (B-4) with CNF-Derived Carbon Supported on the Surface
In the same manner as in Production Example 2, except that 9945 g of FeSO ₄ · 7H ₂ O was added to the total amount of the slurry b ₂ to obtain a slurry b 3, phosphorus in which 2.0 mass% of carbon derived from cellulose nanofibers was supported Granulate (C-4) (LiFePO ₄ , amount of carbon = 2.0% by mass, average particle diameter: 10 μm, porosity 52% by volume, tap density 0) consisting of lithium iron oxide secondary particles (B-4) .9 g / cm ³ ).

Production Example 6: Production of Granulated Body (C-5) Consisting of Lithium-Based Polyanion Particles (B-5) with CNF-Derived Carbon Supported on the Surface]
After 8945 g of FeSO ₄ · 7 H ₂ O was added to the total amount of the slurry b ₂ to obtain a slurry b 3, the amount of water added to the obtained dehydrated cake b 4 was changed to 12 L to have a solid content concentration of 25 mass% In the same manner as in Production Example 2 except that a slurry b5 was obtained, and the drying temperature in spray drying was changed to 140 ° C., lithium iron phosphate having 2.0 mass% of cellulose nanofiber-derived carbon supported on the surface Granulate (C-5) (LiFePO ₄ , amount of carbon = 2.0% by mass, average particle diameter: 9 μm, porosity 61% by volume, tap density 0.8 g / cm) consisting of the following particles (B-5) ³ ) got.

Production Example 7: Production of Granulated Body (C-6) Consisting of Lithium-Based Polyanion Particles (B-6) with CNF-Derived Carbon Supported on the Surface]
After 8945 g of FeSO ₄ · 7 H ₂ O was added to the total amount of the slurry b ₂ to obtain a slurry b 3, the amount of water added to the obtained dehydrated cake b 4 was changed to 17 L to have a solid content concentration of 20 mass% In the same manner as in Production Example 2 except that a slurry b5 was obtained, and the drying temperature in spray drying was changed to 150 ° C., lithium iron phosphate having 2.0 mass% of cellulose nanofiber-derived carbon supported on its surface Granulate (C-6) (LiFePO ₄ , amount of carbon = 2.0% by mass, average particle diameter: 9 μm, porosity 70% by volume, tap density 0.7 g / cm) consisting of the following particles (B-6) ³ ) got.

Production Example 8 Production of Granulated Body (C-7) Consisting of Lithium-Based Polyanion Particles (B-7) with CNF-Derived Carbon Supported on the Surface
The amount of water added to the dewatered cake b4 was changed to 0.5 L to obtain a slurry b5 having a solid content concentration of 55% by mass, and then the drying temperature in spray drying was changed to 180 ° C. Granulated body (C-7) (LiMn _0.7 Fe _0.3 PO ₄ ) comprising lithium manganese iron phosphate secondary particles (B-7) on the surface of which 2.0 mass% of cellulose nanofiber derived carbon is supported on the surface An amount of carbon = 2.0% by mass, an average particle diameter: 11 μm, a porosity of 6% by volume, and a tap density of 1.2 g / cm ³ ).

Production Example 9 Production of Granulated Body (C-8) Consisting of Lithium-Based Polyanion Particle (B-8) with CNF-Derived Carbon Supported on the Surface
The amount of water added to the dewatered cake b4 was changed to 0.5 L to obtain a slurry b5 having a solid content concentration of 55 mass%, and then the drying temperature in spray drying was changed to 200 ° C. Granulated body (C-8) (LiMn _0.7 Fe _0.3 PO ₄ ) comprising lithium manganese iron phosphate secondary particles (B-8) on the surface of which 2.0 mass% of cellulose nanofiber derived carbon is supported on the surface An amount of carbon = 2.0% by mass, an average particle diameter: 10 μm, a porosity of 9% by volume, and a tap density of 1.2 g / cm ³ ).

Production Example 10 Production of Granulated Body (C-9) Consisting of Lithium-Based Polyanion Particle (B-9) with CNF-Derived Carbon Supported on the Surface
The amount of water added to the dewatered cake b4 was changed to 1.5 L to obtain a slurry b5 having a solid content concentration of 50 mass%, and then the drying temperature in spray drying was changed to 200 ° C. Te, granule consisting of 2.0 wt% of cellulose nanofibers phosphate derived carbon is supported on the surface ferromanganese lithium secondary particles (B-9) (C- 9) (LiMn 0.7 Fe 0.3 PO 4 An amount of carbon = 2.0% by mass, an average particle diameter: 20 μm, a porosity of 14% by volume, and a tap density of 1.1 g / cm ³ ).

Production Example 11 Production of Granulated Body (C-10) Composed of Lithium-Based Polyanion Particle (B-10) with CNF-Derived Carbon Supported on the Surface
After the addition of 8945 g of FeSO ₄ · 7 H ₂ O to the total amount of the slurry b ₂ to obtain a slurry b 3, the amount of water added to the dewatered cake b 4 is changed to 2.5 L to obtain a slurry with a solid content concentration of 45 mass% A granulated product (C--) composed of lithium iron phosphate secondary particles (B-10) carrying 2.0% by mass of carbon from cellulose nanofibers in the same manner as in Production Example 2 except that b5 was obtained 10) (LiFePO ₄ , amount of carbon = 2.0% by mass, average particle diameter: 12 μm, porosity 27% by volume, tap density 1.0 g / cm ³ ) was obtained.

Production Example 12 Production of Granulated Body (C-11) Consisting of Lithium-Based Polyanion Particle (B-11) with CNF-Derived Carbon Supported on the Surface
After the addition of only 8945 g of FeSO ₄ · 7 H ₂ O to the total amount of the slurry b ₂ to obtain a slurry b 3, the amount of water added to the obtained dehydrated cake b 4 is changed to 8 L to have a solid content concentration of 30 mass% A slurry K5 was obtained, and lithium iron phosphate secondary particles supporting 2.0 mass% of cellulose nanofiber-derived carbon in the same manner as in Production Example 2 except that the drying temperature in spray drying was changed to 170 ° C. Granulated body (C-11) consisting of (B-11) (LiFePO ₄ , amount of carbon = 2.0% by mass, average particle diameter: 15 μm, porosity 44% by volume, tap density 1.0 g / cm ³ ) I got

[Example 1: Production of positive electrode active material composite (Z-1) for lithium ion secondary battery]
Using 350 g of the complex (A) obtained in Production Example 1 and 150 g of the granules (C-1) obtained in Production Example 2 at 2600 rpm using Mechanofusion (AMS-Lab, manufactured by Hosokawa Micron Corporation) The compounding treatment for 5 minutes was performed to obtain a positive electrode active material complex (Z-1) (particles (A): particles (B-1) = 70: 30 (mass ratio)) for a lithium ion secondary battery.

Example 2 Production of Positive Electrode Active Material Complex (Z-2) for Lithium Ion Secondary Battery
In the same manner as in Example 1, except that the granulated body (C-2) obtained in Production Example 3 was used instead of the granulated body (C-1) obtained in Production Example 2, lithium ion The positive electrode active material complex (Z-2) (particles (A): particles (B-2) = 70: 30 (mass ratio)) of a secondary battery positive electrode was obtained.

[Example 3: Production of positive electrode active material composite (Z-3) for lithium ion secondary battery]
Using 450 g of the complex (A) obtained in Production Example 1 and 50 g of the granulated product (C-3) obtained in Production Example 4 at 2600 rpm using Mechanofusion (AMS-Lab, manufactured by Hosokawa Micron Corporation) The compounding treatment for 5 minutes was performed to obtain a positive electrode active material complex (Z-3) (particles (A): particles (B-3) = 90: 10 (mass ratio)) for a lithium ion secondary battery.

[Example 4: Production of positive electrode active material composite (Z-4) for lithium ion secondary battery]
In the same manner as in Example 1 except that the granulated body (C-4) obtained in Production Example 5 was used instead of the granulated body (C-1) obtained in Production Example 2, lithium ion The positive electrode active material complex (Z-4) (particles (A): particles (B-4) = 70: 30 (mass ratio)) of a secondary battery was obtained.

[Example 5: Production of positive electrode active material composite (Z-5) for lithium ion secondary battery]
Lithium ion was prepared in the same manner as in Example 1, except that the granulate (C-5) obtained in Production Example 6 was used instead of the granulate (C-1) obtained in Production Example 2. The positive electrode active material complex (Z-5) for the secondary battery (particle (A): particle (B-5) = 70: 30 (mass ratio)) was obtained.

[Example 6: Production of positive electrode active material composite (Z-6) for lithium ion secondary battery]
Using Mechanofusion (manufactured by Hosokawa Micron, AMS-Lab) at 2600 rpm, using 400 g of the complex (A) obtained in Production Example 1 and 100 g of the granules (C-6) obtained in Production Example 7 The compounding treatment for 5 minutes was performed to obtain a positive electrode active material complex (Z-6) (particles (A): particles (B-6) = 80: 20 (mass ratio)) for a lithium ion secondary battery.

[Comparative Example 1: Production of positive electrode active material composite (Z-7) for lithium ion secondary battery]
In the same manner as in Example 1 except that the granulated body (C-7) obtained in Production Example 8 was used instead of the granulated body (C-1) obtained in Production Example 2, lithium ion The positive electrode active material complex (Z-7) (particles (A): particles (B-7) = 70: 30 (mass ratio)) of a secondary battery was obtained.

Comparative Example 2 Production of Positive Electrode Active Material Complex (Z-8) for Lithium Ion Secondary Battery
In the same manner as in Example 1, except that the granulated body (C-8) obtained in Production Example 9 was used instead of the granulated body (C-1) obtained in Production Example 2, a lithium ion A positive electrode active material complex (Z-8) (particles (A): particles (B-8) = 70: 30 (mass ratio)) of a secondary battery was obtained.

Comparative Example 3 Production of Positive Electrode Active Material Complex (Z-9) for Lithium Ion Secondary Battery
Using Mechanofusion (manufactured by Hosokawa Micron, AMS-Lab) at 2600 rpm, using 400 g of the complex (A) obtained in Production Example 1 and 100 g of the granules (C-9) obtained in Production Example 10 The compounding treatment for 5 minutes was performed to obtain a positive electrode active material complex (Z-9) (particles (A): particles (B-9) = 80: 20 (mass ratio)) for a lithium ion secondary battery.

Comparative Example 4 Production of Positive Electrode Active Material Composite (Z-10) for Lithium Ion Secondary Battery
In the same manner as in Example 1, except that the granulated body (C-10) obtained in Production Example 11 was used instead of the granulated body (C-1) obtained in Production Example 2, lithium ion A positive electrode active material complex (Z-10) (particles (A): particles (B-10) = 70: 30 (mass ratio)) of a secondary battery was obtained.

Comparative Example 5 Production of Positive Electrode Active Material Composite (Z-11) for Lithium Ion Secondary Battery
Using 450 g of the complex (A) obtained in Production Example 1 and 50 g of the granulated product (C-11) obtained in Production Example 12 at 2600 rpm using Mechanofusion (manufactured by Hosokawa Micron, AMS-Lab) The compounding treatment for 5 minutes was performed to obtain a positive electrode active material complex (Z-11) (particles (A): particles (B-11) = 90: 10 (mass ratio)) for a lithium ion secondary battery.

«Evaluation of disintegration strength of granulated body (C)»
The disintegration strength was evaluated about the granulated body (C) used by the Example and the comparative example. Specifically, 3 g of the granulated body (C) is placed in a cylindrical container having a diameter of 20 mm, and a layer of the granulated body (C) in a closely packed state after repeated tapping 10 times from a height of 1 cm After measuring the layer thickness t ₁₀ (mm) of the granulated body (C) when applying a load of 10 KN from the top to the thickness t ₀ (mm) and the densely packed granulated body (C), The collapse strength was calculated according to the above equation (1).
The results are shown in Table 1.

<< Evaluation of particle (B) coverage of particle (A) surface by X-ray photoelectron spectroscopy >>
About the positive electrode active material composite (Z) for lithium ion secondary batteries obtained in Examples and Comparative Examples, the elements present on the surface of the composite particles were analyzed using X-ray photoelectron spectroscopy (XPS).
Specifically, the peak intensity of Ni2p _3/2 derived from NCM, the peak intensity of P2p derived from particle (B) and the peak of C1s in the obtained X-ray photoelectron spectroscopy spectrum (using device: JPS 9010MX manufactured by Nippon Denshi Co., Ltd.) From the intensities, the XPS peak intensity ratio (C) was determined by the following equation (2). The smaller the value of this XPS peak intensity ratio (C), the lower the value of the lithium composite oxide secondary particle (A) is, the more the surface of the lithium-based polyanion particle (B) is covered.
The results are shown in Table 2.
XPS peak intensity ratio (C) = (peak intensity of Ni ₂ p _3/2 ) /
((P2p peak intensity) + (C1s peak intensity)) (2)

<< Evaluation of particle (B) coating strength on particle (A) surface by X-ray photoelectron spectroscopy >>
Using a high-speed mixer (FILMIX 40L type manufactured by PRIMIX Corporation) 2000 rpm using 2 g of the positive electrode active material complex (Z) for lithium ion secondary batteries obtained in Examples and Comparative Examples and 10 g of N-methyl-2-pyrrolidone The mixture was stirred and kneaded for 3 minutes. The stirring and kneading process is a process emphasizing the step of applying the positive electrode slurry to the current collector in the actual production process of the secondary battery, and the force applied in the actual application step is greater than the shear force applied. It will be added to the body (Z).
The slurry after the stirring and kneading treatment is dried at 80 ° C. for 12 hours using a hot air drier, and then collected for the positive electrode active material composite (Z) for lithium ion secondary battery in the same manner as above, by X-ray photoelectron spectroscopy The XPS peak intensity ratio (D) obtained using the method is determined, and the ratio to the XPS peak intensity ratio before the stirring and kneading treatment ((XPS peak intensity ratio (D)) / (XPS peak intensity ratio (C) From the above), the coating strength of lithium-based polyanion particles (B) on the surface of lithium composite oxide secondary particles (A) was evaluated.
The ratio (D / C) of this XPS peak intensity ratio is smaller, and the lithium composite oxide secondary particles (A) have a value closer to 1, and lithium-based polyanion particles (B) in which carbon is firmly supported on the surface Indicates that it is covered.
The results are shown in Table 2.

«Transition metal elution amount to electrolyte solution»
Using the positive electrode active material composite for lithium ion secondary batteries obtained in all the Examples and Comparative Examples as a positive electrode material, a positive electrode of a lithium ion secondary battery was produced. Specifically, the obtained positive electrode active material complex for a lithium ion secondary battery, acetylene black and polyvinylidene fluoride are mixed in a blending ratio of 90: 5: 5 in mass ratio, and N-methyl-2-pyrrolidone is added thereto. And the mixture was sufficiently kneaded to prepare a positive electrode slurry. The positive electrode slurry was applied to a current collector made of an aluminum foil with a thickness of 20 μm using a coating machine, and vacuum drying was performed at 80 ° C. for 12 hours. Then, it punched out in disk shape of (phi) 14 mm, and pressed for 2 minutes at 16 MPa using a hand press, and it was set as the positive electrode.
Subsequently, a coin-type secondary battery was constructed using the above positive electrode. As a negative electrode, a lithium foil (in the case of a lithium ion secondary battery) punched out to φ 15 mm was used. The electrolytic solution volume of ethylene carbonate and ethyl methyl carbonate ratio of 3: 7 mixed solvent in a mixing ratio of, with a LiPF ₆ that was dissolved at a concentration of 1 mol / L. For the separator, a known one such as a polymeric porous film such as polypropylene was used. These battery parts were incorporated and stored in an atmosphere having a dew point of −50 ° C. or less by a conventional method to obtain a coin-type secondary battery (CR-2032).

The obtained secondary battery was charged. Specifically, constant current charging at a current of 170 mA / g and a voltage of 4.5 V was performed.
Thereafter, the secondary battery was disassembled, and the taken-out positive electrode was washed with dimethyl carbonate and then immersed in an electrolytic solution. The electrolyte used at this time was prepared by dissolving LiPF ₆ at a concentration of 1 mol / L in a mixed solvent in which ethylene carbonate and ethyl methyl carbonate were mixed at a ratio of 1: 1 in volume ratio. The electrolytic solution in which the positive electrode was immersed was placed in a closed vessel and allowed to stand at 70 ° C. for one week.
After standing, the electrolytic solution from which the positive electrode was taken out was filtered with a 0.45 μm dissic filter and acid-decomposed with nitric acid. Mn, Co, and Ni derived from the positive electrode active material complex for lithium ion secondary batteries contained in the acid-decomposed electrolytic solution were quantified using ICP emission spectroscopy (using apparatus: ULTIMA 2 manufactured by Horiba, Ltd.).
The results are shown in Table 2.

«Evaluation of discharge characteristics»
Using the secondary battery manufactured by the above evaluation of the transition metal elution amount to the electrolytic solution, a discharge capacity measuring device (HJ-1001SD8, manufactured by Hokuto Denko) at a temperature of 30 ° C., 0.2 C (34 mAh / hour). The initial discharge capacities of g) and 3C (510 mAh / g) were measured.
The results are shown in Table 2.

From the results of Tables 1 and 2, the granulated body (C) used in the examples has high disintegration property, so lithium-based polyanion particles are dense and over a wide range on the surface of the positive electrode active material composite for lithium ion secondary batteries. It can be seen that it is firmly coated.
Therefore, good discharge capacity is expressed in the obtained secondary battery.

Claims (7)

The following formula (I) or (II):
LiNi _a Co _b Mn _c M ¹ _x O ₂ (I)
(In the formula (I), M ¹ represents Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, And one or more elements selected from Bi and Ge, a, b, c, x, 0.3 ≦ a <1, 0 <b ≦ 0.7, 0 <c ≦ 0.7, Indicates a number satisfying 0 ≦ x ≦ 0.3 and 3a + 3b + 3c + (valence of M ¹ ) × x = 3)
LiNi _d Co _e Al _f M ² _y O ₂ (II)
(Wherein M ² is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi, and D represents one or more elements selected from Ge, d, e, f and y each satisfy 0.4 ≦ d <1, 0 <e ≦ 0.6, 0 <f ≦ 0.3, 0 ≦ It shows a number satisfying y ≦ 0.3 and 3d + 3e + 3f + (valence of M ² ) × y = 3)
In the surface of lithium composite oxide secondary particles (A) consisting of lithium composite oxide particles represented by the following formula (III):
LiFe _m Mn _n M ³ _o PO ₄ (III)
(In the formula (III), M ³ represents Co, Ca, Sr, Y, Zr, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd. M, n, and o satisfy 0 ≦ m ≦ 1, 0 ≦ n ≦ 1, 0 ≦ o ≦ 0.3, and m + n ≠ 0 are satisfied, and 2m + 2n + (valence number of M ³ ) × o = 2 is satisfied.)
A method for producing a positive electrode active material complex for a lithium ion secondary battery, comprising the step of coating a lithium-based polyanion particle (B) having a surface supported by carbon and being supported on the surface, comprising the steps of Z):
(X) A lithium mixed oxide containing a lithium compound, a nickel compound, a cobalt compound, and a manganese compound, or a mixed powder containing a lithium compound, a nickel compound, a cobalt compound, and an aluminum compound is fired to form a lithium composite oxide Obtaining secondary particles (A),
(Y) A lithium compound, a metal compound containing at least an iron compound or a manganese compound, and a phosphoric acid compound are subjected to a hydrothermal reaction, lithium-based polyanion primary particles obtained, and a slurry containing a carbon source are spray-dried to granulate And calcining to adjust the porosity to 45 to 80% by volume, and obtaining a granulated body (C) comprising lithium-based polyanion particles (B) having carbon supported on the surface, and (Z ) The lithium composite oxide secondary particles (A) obtained in step (X) and the granules (C) obtained in step (Y) are mixed while applying compressive force and shear force to produce A positive electrode for a lithium ion secondary battery, comprising a step of combining the lithium composite oxide secondary particles (A) and the lithium-based polyanion particles (B) having carbon supported on the surface thereof while disintegrating the particles (C) Active material Method of manufacturing a complex.   The positive electrode active material composite for a lithium ion secondary battery according to claim 1, wherein in the step (Y), the solid content concentration of the slurry used is 9 to 35% by mass, and the temperature of spray drying is 110 to 160 ° C. Manufacturing method.   The method for producing a positive electrode active material complex for a lithium ion secondary battery according to claim 1 or 2, wherein a time of complexation in the step (Z) is 1 to 10 minutes. The tap density of the granule (C) obtained by process (Y) is less than 1.0 g / cm < ³ >, The positive electrode active material composite for lithium ion secondary batteries of any one of Claims 1-3. How to make the body.   The disintegration strength of the granulated body (C) obtained by process (Y) is 1.8 KN / mm or less, The positive electrode active material complex for lithium ion secondary batteries of any one of Claims 1-4. Manufacturing method.   The carbon supported on the surface of the lithium-based polyanion particles (B) is carbon derived from cellulose nanofibers or carbon derived from a water-soluble carbon material, The lithium ion secondary battery according to any one of claims 1 to 5 Method of producing a positive electrode active material composite   The average particle size of the lithium-based polyanion primary particles used in the step (Y) is 50 to 250 nm, and the average particle size of the granules (C) is 5 to 15 μm. The manufacturing method of the positive electrode active material complex for lithium ion secondary batteries as described in 4.