KR20140023861A - Cathode active material, method of fabricating the same and battery having the same - Google Patents

Abstract

The present invention relates to an anode active material for lithium secondary batteries, a manufacturing method thereof, and a secondary battery having the same, more specifically to an anode active material, comprising: an anode active material core; and a conductive barrier layer comprising at least one selected from a group comprising antimony zinc oxide, antimony tin oxide, or their composition; a manufacturing method thereof; and a secondary battery comprising the same. The anode active material has a pore where the conductive barrier layer connects the anode active material core from the surface of the anode active material.

Description

Cathode active material, method of manufacturing the same and a secondary battery comprising the same {Cathode active material, method of fabricating the same and battery having the same}

The present invention relates to a positive electrode active material for a lithium secondary battery, a method for manufacturing the same, and a secondary battery including the same, more specifically, a positive electrode active material core; And it relates to a positive electrode active material for a lithium secondary battery, a manufacturing method thereof and a secondary battery comprising the same, a conductive barrier layer formed of antimony zinc oxide, antimony tin oxide or a combination thereof formed on the positive electrode active material core.

A secondary battery is a battery which can be charged and discharged using an electrode material having excellent reversibility, and is a nickel-hydrogen (Ni-MH) battery, a lithium (Li) battery, a lithium ion (Li-ion) battery, etc., depending on the positive and negative electrode materials. It can be divided into. Such secondary batteries are increasingly being applied as a power source for smart devices such as smart phones, portable computers, and electronic devices such as electronic paper, or vehicles such as bicycles and electric vehicles.

Recently, the demand for secondary batteries such as lithium batteries, lithium ion batteries, and lithium ion polymer batteries has been greatly increased. However, these secondary batteries generally have a large resistance component at the interface between the positive electrode active material and the electrolyte, the interface between the negative electrode active material and the electrolyte, or the electrolyte itself as the number of charge / discharge cycles increases. Because of this, the service life is shortened. In particular, in the case of the positive electrode, since the oxidation reaction occurs at a higher voltage than the negative electrode, the resistance component is mainly due to decomposition by-products of the electrolyte generated on the positive electrode side. The decomposition reaction of the electrolyte may generate a lot of gas to reduce the contact inside the battery to increase the resistance or increase the viscosity of the electrolyte to interfere with the flow of lithium ions.

The decomposition reaction may be affected by the kind of impurities (LiOH, Li ₂ CO ₃ ) present on the surface of the positive electrode active material, or by structural defects on the surface of the positive electrode active material. As such, when structural defects exist on the surface of the active material, addition reaction between the electrolyte and the active material is further promoted during charging and discharging, and the structure of the positive electrode active material collapses and elutes due to the change of crystal lattice, As the number of times increases, the capacity of the battery gradually decreases.

An object of the present invention is to provide a cathode active material for secondary batteries exhibiting high capacity and high output characteristics by suppressing the interfacial reaction with the electrolyte solution in order to solve the problems of the prior art as described above.

Moreover, an object of this invention is to provide the manufacturing method which can form the positive electrode active material by this invention economically and quickly in large quantities.

In addition, another technical problem to be solved by the present invention is to provide a secondary battery using the positive electrode active material having the above-described advantages.

A cathode active material according to an embodiment of the present invention for solving the technical problem is a cathode active material core; And a conductive barrier layer formed on at least one selected from the group consisting of antimony zinc oxide, antimony tin oxide, and a combination thereof on the positive electrode active material core. The conductive barrier layer has pores for communicating the cathode active material core from the surface of the cathode active material.

In some embodiments, the antimony zinc oxide may include any one or a mixture of compounds represented by the following Chemical Formula 1 or 2.

(ZnO ₂ ) x (Sb ₂ O ₃ ) y, x + y ≦ 1, 0 <y / x ≦ 2

(ZnO ₂ ) x (Sb ₂ O ₅ ) y, x + y ≦ 1, 0 <y / x ≦ 2

In addition, in some embodiments, the antimony tin oxide may include any one or a mixture of compounds represented by the following Chemical Formula 3 or 4.

(SnO ₂ ) x (Sb ₂ O ₃ ) y, x + y ≦ 1, 0 <y / x ≦ 2

(SnO ₂ ) x (Sb ₂ O ₅ ) y, x + y ≦ 1, 0 <y / x ≦ 2

The conductive barrier layer includes a sintered body of nanoparticles selected from the group consisting of the antimony zinc oxide, antimony tin oxide, and combinations thereof, wherein pores are provided by spaces between adjacent nanoparticles. The nanoparticles may have an average particle diameter in the range of 1 nm to 200 nm. The nanoparticle particle diameter may have a standard deviation within the range of 1 nm to 50 nm.

The conductive barrier layer may have a thickness in the range of 2 to 500 particle layers of the nanoparticles, and may be in the range of 2 nm to 500 nm.

The positive electrode active material core is _{Li a A 1 - b X b} D 2 (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5); _{Li a A 1 - b X b} O 2 -c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li _a E _{1 - b} X _b O _{2 - c} D _c (0.90? A? 1.8, 0? B? 0.5, 0? C? 0.05); _{Li a E 2 - b X b} O 4 - c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li _a Ni _{1 -b - c} Co _b X _c D _а (0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, 0 <α ≦ 2); Li _a Ni _{1 -b - c} Co _b X _c O _{2 -α} Т _α (0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, 0 <α <2); Li _a Ni _{1 -b - c} Co _b X _c O _{2 -α} Т ₂ (0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, 0 <α <2); Li _a Ni _{1 -b - c} Mn _b X _c D _а (0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, 0 <α ≦ 2); Li _a Ni _{1 -b - c} Mn _b X _c O _{2 -α} Т _α (0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, 0 <α <2); Li _a Ni _{1 -b - c} Mn _b X _c O _{2 -α} Т ₂ (0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, 0 <α <2); Li _a Ni _b E _c G _d O ₂ (0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.9, 0 ≦ c ≦ 0.5, 0.001 ≦ d ≦ 0.1); Li _a Ni _b Co _c Mn _d GeO ₂ (0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.9, 0 ≦ c ≦ 0.5, 0 ≦ d ≦ 0.5, 0.001 ≦ e ≦ 0.1); Li _a NiG _b O ₂ (0.90? A? 1.8, 0.001? B? 0.1); Li _a CoG _b O ₂ (0.90? A? 1.8, 0.001? B? 0.1); Li _a MnG _b O ₂ (0.90? A? 1.8, 0.001? B? 0.1); Li _a Mn ₂ G _b O ₄ (0.90? A? 1.8, 0.001? B? 0.1); Li _a Mn _{1 - g} G _g PO ₄ (0.90? A? 1.8, 0? G? 0.5); QO _2; QS ₂ ; LiQS ₂ ; LiZO ₂ ; LiNiVO _4; Li _(3-f) J ₂ (PO ₄ ) ₃ (0? F? 2); Li _(3-f) Fe ₂ (PO ₄ ) ₃ (0? F? 2); LiFePO _4; FeF ₃ ; _{Li 5 Fe 1 - x X x} O 4 - y T y (0 ≤ x ≤ 1, 0 ≤ y ≤ 1); AV ₂ O ₆ ; Li _x V ₃ O ₈ (0 ≦ x ≦ 1); Li _x V ₂ O ₅ (0 ≦ x ≦ 1); Li _x AVO ₄ (0 ≦ x ≦ 1); JRu ₂ O ₄ ; Li ₂ RuO ₃ ; MoO _x (2.9 <x <3.1); Mo _x Ru _{1 - x} O ₂ (0 ≦ x ≦ 1); LiG _B O ₃ ; LiFeSO ₄ F; Fe ₂ (SO ₄ ) ₃ ; Li ₂ GSiO ₄ ; J ₂ GP ₂ O ₇ ; LiFePO ₄ F; LiTiPO ₄ F; LiVPO ₄ O; LiVPO ₄ F; J ₃ V ₂ (PO ₄ ) ₂ F ₃ ; J ₃ V ₂ (PO ₄ ) ₃ ; J ₂ XPO ₄ F; Li ₂ FeSiPO ₄ ; LiX ₂ PO ₄ ; Li _x Mn _{2 - y} X _y O _{4 - z} T _z (0.8 ≦ x ≦ 1.8, 0 ≦ y ≦ 0.6, 0 ≦ z ≦ 0.6); (A is selected from the group consisting of Ni, Co, Mn, and combinations thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, Ti, Zr, rare earth elements and combinations thereof D is selected from the group consisting of O, F, S, P and combinations thereof; E is selected from the group consisting of Co, Mn and combinations thereof; T is F, S, P and G is selected from the group consisting of a combination thereof; G is selected from the group consisting of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V and combinations thereof; J is Li, Na and combinations thereof Q is selected from the group consisting of Ru, Mo, Mn, Ti, V and combinations thereof, Z is selected from the group consisting of Cr, V, Fe, Sc, Y and combinations thereof; J is selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, and combinations thereof) or any combination thereof. have.

Method for manufacturing a positive electrode active material according to an embodiment of the present invention for solving the other technical problem,

Antimony-containing zinc oxide (AZO) nanoparticles represented by Formula 1 or 2 and antimony tin oxide represented by Formula 3 or 4 in any one or two or more dispersed solvents of alcohol-based, ether-based and ketone-based solvents. adding one or more particles selected from the group consisting of nanoparticles of antimony-containing tin oxide (ATO) to form a dispersion solution;

Providing positive electrode active material particles in the dispersion solution;

Stirring the dispersion solution including the cathode active material particles to form intermediate particles having the nanoparticles adsorbed on the cores of the cathode active material particles; And

Heat treating the obtained intermediate particles and sintering the nano-sized particles to form a conductive barrier layer having pores on a core of the cathode active material particles.

The antimony zinc oxide may include any one or a mixture of compounds represented by the following Chemical Formula 1 or 2.

(ZnO ₂ ) x (Sb ₂ O ₃ ) y, x + y ≦ 1, 0 <y / x ≦ 2

(ZnO ₂ ) x (Sb ₂ O ₅ ) y, x + y ≦ 1, 0 <y / x ≦ 2

In addition, the antimony tin oxide may include any one or a mixture of stoichiometric compositions represented by the following formula (3) or (4).

(SnO ₂ ) x (Sb ₂ O ₃ ) y, x + y ≦ 1, 0 <y / x ≦ 2

(SnO ₂ ) x (Sb ₂ O ₅ ) y, x + y ≦ 1, 0 <y / x ≦ 2

The nanoparticles have an average particle diameter in the range of 1 nm to 200 nm, and the dispersion of the nanoparticles may have a standard deviation in the range of 1 nm to 50 nm.

In the manufacturing method according to the present invention, in the forming of the dispersion solution, the nanoparticles may be added in a ratio of 0.1% to 50% by weight based on 100% by weight of the dispersion solution. In addition, in the providing of the cathode active material particles, the cathode active material particles may be added in a ratio of 10% by weight to 200% by weight based on 100% by weight of the dispersion solution to which the nanoparticles are added.

The conductive barrier layer may have a thickness in the range of 2 to 500 particle layers of the nano-sized particles, specifically, in the range of 2 nm to 500 nm.

The alcohol solvent is methanol, ethyl alcohol, methyl alcohol, glycerol, propylene glycol, isopropyl alcohol, isobutyl alcohol, polyvinyl alcohol, cyclohexanol, octyl alcohol, decanol, hexatecanol, ethylene glycol, 1.2- Octanediol, 1,2-dodecanediol and 1,2-hexadecanediol, or a mixture thereof. In addition, the ether solvent is acetone, hexane, octyl ether, butyl ether, hexyl ether, benzyl ether, phenyl ether, decyl ether, ethyl methyl ether, dimethyl ether, diethyl ether, diphenyl ether, tetrahydrofuran (THF ), 1,4-dioxane, polyethylene glycol (PEG), polypropylene glycol (PPG), polytetramethylene glycol (PTMG) and polyoxymethylene (POM), polytetrahydrofuran, or a mixture thereof. Can be. The ketone solvent is methyl ethyl ketone, cyclohexanone, 4-hydroxy-4-methyl-2-pentanone, methyl-n-propyl ketone, methyl-n-butyl ketone, methyl-n-amyl ketone, 2 -Heptanone, or a mixture thereof.

The heat treatment may be performed in the range of 100 ℃ to 1000 ℃.

According to another aspect of the present invention, there is provided a battery including a cathode, an anode, and a separator electrically separating the cathode and the anode, wherein the cathode is in the aforementioned embodiments. It may be a lithium secondary battery comprising a positive electrode active material according to.

According to an embodiment of the present invention, a conductive barrier layer formed of at least one selected from the group consisting of antimony zinc oxide, antimony tin oxide, and combinations thereof passivates the surface of the positive electrode active material core so that the positive electrode active material core is an electrolyte solution. By preventing direct exposure to the battery, it is possible to suppress the addition reaction between the electrolyte solution and the positive electrode active material core which generate a large resistance component in the battery during the charge / discharge cycle of the battery, and thereby the structural collapse of the positive electrode active material core. .

In addition, the conductive barrier layer itself has electronic conductivity, and not only has excellent ion transport ability to transfer metal ions such as lithium ions to the positive electrode active material core, but also has chemical resistance to the electrolyte, thereby providing a long service life. While having a low internal resistance, a cathode active material for a secondary battery capable of high speed and high efficiency of charging and discharging may be provided.

Further, according to an embodiment of the present invention, the nano-size particles are directly applied by adsorption on a positive electrode active material core by using nano-sized particles having preformed and uniform sizes, not precursor forms, and sintered by heat treatment. By doing so, a method of manufacturing a cathode active material capable of manufacturing the cathode active material in large quantities can be provided simply and economically without the need for a separate firing process.

In addition, according to the embodiment of the present invention, a secondary battery having a high output and a long life having the above-described advantages can be provided.

1A is a cross-sectional view illustrating a structure of a cathode active material according to an exemplary embodiment of the present invention, and FIG. 1B is a partially enlarged view of a portion indicated by a dotted line A of FIG. 1A.
2A and 2B schematically illustrate a flowchart illustrating a method of manufacturing a cathode active material according to an embodiment of the present invention, and an apparatus for manufacturing a cathode active material therefor.
3A is a transmission electron microscope image showing nano-sized particles (AZO) of AZO dispersed in a dispersion solution according to one embodiment of the invention, Figure 3b is AZO nano-sized particles formed on the active material core of LiCoO ₂ ( A transmission electron microscope image showing a cross section of the conductive barrier layer of AZO).
4A is a transmission electron microscope image showing nano-sized particles (ATO) of ATO dispersed in a dispersion solution according to one embodiment of the present invention, Figure 4b is ATO nano-sized particles formed on the active material core of LiCoO ₂ It is a transmission electron microscope image which shows the cross section of the conductive barrier layer of (ATO).
5 is a scanning electron microscope image showing a LiCoO ₂ positive electrode active material according to a comparative example of the invention.
6 is a graph showing the discharge performance according to the rate of the coin battery according to an embodiment and a comparative example of the present invention.
7 is a graph illustrating life characteristics of a coin battery according to an embodiment and a comparative example of the present invention.
FIG. 8 is a graph illustrating impedance values after initial cycle (1 cycle) and after 100 cycles of a coin battery according to one embodiment and a comparative example of the present invention.
9 is a graph showing a measurement result according to the cyclic voltage scanning method after the initial charge and discharge (1 cycle) and after 100 cycles of a coin battery according to an embodiment and a comparative example of the present invention.
10 is a scanning electron microscope image showing a cathode active material prepared in Comparative Examples and Examples of the present invention.
11 is a graph showing the discharge performance according to the rate of the coin battery according to an embodiment and a comparative example of the present invention.
12 is a graph showing cycle characteristics of a coin battery according to an embodiment and a comparative example of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments of the present invention are described in order to more fully explain the present invention to those skilled in the art, and the following embodiments may be modified into various other forms, It is not limited to the embodiment. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art.

In addition, in the following drawings, the thickness or size of each layer is exaggerated for convenience and clarity of description, the same reference numerals in the drawings refer to the same elements. As used herein, the term "and / or" includes any and all combinations of any of the listed items.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" include singular forms unless the context clearly dictates otherwise. Also, &quot; comprise "and / or" comprising "when used herein should be interpreted as specifying the presence of stated shapes, numbers, steps, operations, elements, elements, and / And does not preclude the presence or addition of one or more other features, integers, operations, elements, elements, and / or groups.

The term 'separation membrane' as used herein includes a separator generally used in a liquid electrolyte battery using a liquid electrolyte having a small affinity with the separator. In addition, the 'membrane' as used herein includes an intrinsic solid polymer electrolyte and / or a gel solid polymer electrolyte in which the electrolyte is strongly bound to the separator, so that the electrolyte and the separator are recognized as the same. Therefore, the separator should be defined in the meaning as defined herein.

1A is a cross-sectional view illustrating a structure of a cathode active material 100 according to an embodiment of the present invention, and FIG. 1B is a partially enlarged view of a portion indicated by a dotted line A of FIG. 1A.

Referring to FIG. 1A, the cathode active material 100 includes a cathode active material core 10 and a conductive barrier layer 20 formed on the cathode active material core 10. The positive electrode active material core 10 may include positive electrode active material particles suitable for a secondary battery. For example, the positive electrode active material core 10 may be a positive electrode active material for a lithium secondary battery capable of intercalating / deintercalating lithium. For example, the cathode active material for a lithium secondary battery may be any one or a combination of lithium, nickel, cobalt, chromium, magnesium, strontium, vanadium, lanthanum, cerium, iron, cadmium, lead, titanium, molybdenum, or manganese. It may be selected from two or more kinds of oxides (oxide), phosphate, sulfide (fluoride), fluoride (fluoride) or a combination thereof. For example, the positive electrode active material is a material having a blank structure material _{(e.g., LiCoO 2, LiCo1 / 3 Mn} 1/3 Ni 1/3 O 2, LiNiO 2), post having a hexagonal layered ammyeong structure (e.g. For example, it may be LiFePO ₄ ), a spinel material having a cubic structure (eg, LiMn ₂ O ₄ ), or V ₂ O ₅ , TiS, MoS, or a combination thereof. However, not necessarily the invention is not limited to this, the positive electrode active material _{Li a A 1 - b X b} D 2 (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5); Li _a A _{1 - b} X _b O _{2 - c} D _c (0.90? A? 1.8, 0? B? 0.5, 0? C? 0.05); Li _a E _{1 - b} X _b O _{2 - c} D _c (0.90? A? 1.8, 0? B? 0.5, 0? C? 0.05); _{Li a E 2 - b X b} O 4 -c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); _{Li a Ni 1 -b- c Co b} X c D а (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 <а ≤ 2); Li _a Ni _{1- b- c} Co _b X _c O _{2 -а} Т _а (0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, 0 <а <2); Li _a Ni _{1 -b - c} Co _b X _c O _{2 -а} Т ₂ (0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, 0 <а <2); Li _a Ni _{1 -b - c} Mn _b X _c D _а (0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, 0 <а ≦ 2); Li _a Ni _{1- bc} Mn _b X _c 0 _2-а Т _а (0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, 0 <а <2); Li _a Ni _1-bc Mn _b X _c 0 _2-а Т ₂ (0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, 0 <а <2); Li _a Ni _b E _c G _d O ₂ (0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.9, 0 ≦ c ≦ 0.5, 0.001 ≦ d ≦ 0.1); Li _a Ni _b Co _c Mn _d GeO ₂ (0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.9, 0 ≦ c ≦ 0.5, 0 ≦ d ≦ 0.5, 0.001 ≦ e ≦ 0.1); Li _a NiG _b O ₂ (0.90? A? 1.8, 0.001? B? 0.1); Li _a CoG _b O ₂ (0.90? A? 1.8, 0.001? B? 0.1); Li _a MnG _b O ₂ (0.90? A? 1.8, 0.001? B? 0.1); Li _a Mn ₂ G _b O ₄ (0.90? A? 1.8, 0.001? B? 0.1); Li _a Mn _{1 - g} G _g PO ₄ (0.90? A? 1.8, 0? G? 0.5); QO _2; QS ₂ ; LiQS ₂ ; LiZO ₂ ; LiNiVO _4; Li _(3-f) J ₂ (PO ₄ ) ₃ (0? F? 2); Li _(3-f) Fe ₂ (PO ₄ ) ₃ (0? F? 2); LiFePO _4; FeF ₃ ; _{Li 5 Fe 1 - x X x} O 4 - y T y (0 ≤ x ≤ 1, 0 ≤ y ≤ 1); AV ₂ O ₆ ; Li _x V ₃ O ₈ (0 ≦ x ≦ 1); Li _x V ₂ O ₅ (0 ≦ x ≦ 1); Li _x AVO ₄ (0 ≦ x ≦ 1); JRu ₂ O ₄ ; Li ₂ RuO ₃ ; MoO _x (2.9 <x <3.1); Mo _x Ru _1-x O ₂ (0 ≦ x ≦ 1); LiG _B O ₃ ; LiFeSO ₄ F; Fe ₂ (SO ₄ ) ₃ ; Li ₂ GSiO ₄ ; J ₂ GP ₂ O ₇ ; LiFePO ₄ F; LiTiPO ₄ F; LiVPO ₄ O; LiVPO ₄ F; J ₃ V ₂ (PO ₄ ) ₂ F ₃ ; J ₃ V ₂ (PO ₄ ) ₃ ; J ₂ XPO ₄ F; Li ₂ FeSiPO ₄ ; LiX ₂ PO ₄ ; Li _x Mn _2-y X _y O _4-z T _z (0.8 ≦ x ≦ 1.8, 0 ≦ y ≦ 0.6, 0 ≦ z ≦ 0.6); (A is selected from the group consisting of Ni, Co, Mn, and combinations thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, Ti, Zr, rare earth elements and combinations thereof D is selected from the group consisting of O, F, S, P and combinations thereof; E is selected from the group consisting of Co, Mn and combinations thereof; T is F, S, P and G is selected from the group consisting of a combination thereof; G is selected from the group consisting of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V and combinations thereof; J is Li, Na and combinations thereof Q is selected from the group consisting of Ru, Mo, Mn, Ti, V and combinations thereof, Z is selected from the group consisting of Cr, V, Fe, Sc, Y and combinations thereof; J is selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, and combinations thereof) or combinations thereof, or other chalcogenide compounds or other compounds It may water.

As shown in FIG. 1A, the positive electrode active material core 10 may be primary particles, but this is exemplary, and the positive electrode active material core 10 may be secondary particles in which a plurality of particles are aggregated. The average diameter D1 of the positive electrode active material core 10 may be in the range of 0.1 μm to 200 μm.

The conductive barrier layer 20 includes any one or combination of antimony zinc oxide (hereinafter referred to as AZO) and antimony tin oxide (hereinafter referred to as ATO). Conventionally, AZO and ATO are widely applied as an optical material or flame retardant such as a sunshade member, but in the present invention, it is applied as an additive of a positive electrode active material. Since AZO and ATO do not contain indium (In), which is a rare earth, unlike indium tin oxide (ITO), which is widely used as a transparent electrode, the material itself has a high economical advantage.

In addition, the conductive barrier layer 20 of AZO and / or ATO includes oxides of antimony, zinc and tin, hydroxides thereof, carbonates, nitrates, acetates, and metal salts such as chlorides, conjugated compounds, chelates, and organics thereof. Since it is not obtained by synthesis in solution using a precursor such as a molecular compound, but is formed directly on the core surface using the nano-sized particles of the AZO and ATO, the conductive barrier layer 20 is formed of the nano-sized particles. Having the same composition as the composition, it is possible to control the resistance value of the conductive barrier layer by adjusting the resistance value in the production of nano-sized particles of AZO and ATO.

Nano-size particles of the AZO and ATO may have a single crystal, polycrystalline or amorphous structure according to the above-described manufacturing method, and antimony oxide (Sb ₂ O ₃ or Sb _{2 to} zinc oxide (ZnO) or tin oxide (SnO ₂ ) The molar ratio of O ₅ ) may be variously selected depending on the resistance thereof. For example, the molar ratio of antimony oxide (Sb ₂ O ₃ or Sb ₂ O ₅ ) / zinc oxide (ZnO) may be 0.05 to 1.9, and antimony oxide (Sb ₂ O ₃ or Sb ₂ O ₅ ) / tin oxide ( The molar ratio of SnO ₂ ) may also be 0.05 to 1.9, and more preferably, the molar ratio may be in the range of 0.05 to 1.2.

The nano-sized particles of the AZO may be any one or a mixture of stoichiometric compositions, such as represented by the formula 1 and 2, the nano-sized particles of the ATO are stoichiometric, represented by the formula 3 and 4 It may be any one of the compositions or mixtures thereof. These nano-sized particles may have a monocrystalline or polycrystalline structure.

(ZnO ₂ ) x (Sb ₂ O ₃ ) y, x + y = 1, 0 <y / x≤2

(ZnO ₂ ) x (Sb ₂ O ₅ ) y, x + y = 1, 0 <y / x≤2

(SnO ₂ ) x (Sb ₂ O ₃ ) y, x + y = 1, 0 <y / x≤2

(SnO ₂ ) x (Sb ₂ O ₅ ) y, x + y = 1, 0 <y / x≤2

Nano-size particles of the AZO and ATO may have an average diameter in the range of 1 nm to 200 nm. When the average diameter of the nanoparticles of the AZO and ATO is less than 1 nm, the cohesion between the particles is increased, so that it is difficult to obtain a good dispersion solution as described below, unless a separate surface treatment or pH is adjusted. In addition, when the size of the particles exceeds 200 nm, non-uniform overgrowth of certain of the nanoparticles is likely to occur during sintering, in this case, between the surface of the positive electrode active material particles 100 and the positive electrode active material core 10 Occlusion of pores to communicate may occur, and the occlusion of pores may reduce the charge and discharge efficiency of the positive electrode by blocking the transfer path of lithium ions and increasing the internal resistance of the battery.

The nanoparticles may be, for example, gelatinization, atomization, pyrolysis, metal alcoholate hydrolysis, chemical co-precipitation crystal growth, It may be formed through a pulverizing or classification process. However, the method of forming such nanoparticles is exemplary and the present invention is not limited thereto.

The conductive barrier layer 20 is added between the positive electrode active material core 10 and the electrolyte EL by preventing the positive electrode active material core 10 from directly contacting the electrolyte EL, as shown in FIG. 1B. The reaction can be suppressed. In addition, by reducing the structural collapse of the positive electrode active material core due to the release of metal ions, for example lithium ions from the positive electrode active material core 10, the life of the positive electrode active material can be improved.

In the present invention, the thickness of the conductive barrier layer 20 is in the range of 2 to 500 particle layer of the above-described nanoparticles, the thickness of the conductive barrier layer may be limited to within the range of 2 nm to 500 nm. When the conductive barrier layer 20 is less than two particle layers of nanoparticles, sufficient coverage of the conductive barrier layer 20 with respect to the positive electrode active material core 10 may not be obtained, and when the conductive barrier layer 20 exceeds 500 particle layers, the positive electrode active material particles 100 The path of arrival of the pores from the surface of the anode to the positive electrode active material core 10 may increase and blockage of the pores may occur during the sintering process, thereby reducing the charge / discharge efficiency of the battery and the amount of the conductive barrier layer 20. As this increases, the overall energy density of the positive electrode active material 100 may decrease.

2A and 2B are diagrams schematically illustrating a method of manufacturing a cathode active material according to an embodiment of the present invention, and an apparatus for manufacturing a cathode active material therefor.

2A and 2B, nanoparticles 20P ′ of AZO or ATO are added to the dispersion solvent SL to form a dispersion solution DL (S10). The dispersion solvent SL may be any one of an alcohol solvent, an ether solvent, and a ketone solvent, or a mixed solvent of two or more solvents.

The alcohol solvent is methanol, ethyl alcohol, methyl alcohol, glycerol, propylene glycol, isopropyl alcohol, isobutyl alcohol, polyvinyl alcohol, cyclohexanol, octyl alcohol, decanol, hexatecanol, ethylene glycol, 1.2- Octanediol, 1,2-dodecanediol and 1,2-hexadecanediol, or mixtures thereof. Preferably, the alcohol solvent may be methanol having the lowest carbon number and being economical. However, this is exemplary and the present invention is not limited thereto. As the alcoholic solvent, other primary alcohols, secondary alcohols and tertiary alcohols or mixtures thereof may be used.

The ether solvent is acetone, hexane, octyl ether, butyl ether, hexyl ether, benzyl ether, phenyl ether, decyl ether, ethyl methyl ether, dimethyl ether, diethyl ether, diphenyl ether, tetrahydrofuran (THF), Cycle ethers such as 1,4-dioxane and polyethers such as polyethylene glycol (PEG), polypropylene glycol (PPG), polytetramethylene glycol (PTMG), polyoxymethylene (POM), polytetrahydrofuran. The aforementioned polyethers are exemplary, and other aliphatic or aromatic polyethers may be used as the ether solvent.

The ketone solvent is, for example, methyl ethyl ketone, cyclohexanone, 4-hydroxy-4-methyl-2-pentanone, methyl-n-propyl ketone, methyl-n-butyl ketone, methyl-n- Amyketone, 2-heptanone, or a mixture thereof may be used, but the present invention is not limited thereto, and other ketone solvents may be used.

The nanoparticles 20P ′ of the AZO and ATO in the dispersion solvent SL may maintain a dispersed state without a separate surface treatment. In some embodiments, the nanoparticles 20P ′ may be provided at 0.1 wt% to 50 wt% based on 100 wt% of the dispersion solution DL.

Thereafter, the cathode active material particles 10P are provided in the dispersion solution DL (S20). The positive electrode active material particles 10P may be provided in the dispersion solution DL by a selected weight ratio so that the nanoparticles may adsorb on the surface of the positive electrode active material particles 10P within a range of 2 to 500 particle layers. For example, the positive electrode active material particles 10P may be added within a range of 10% to 200% by weight based on 100% by weight of the dispersion solution DL in which the nanoparticles 20P 'are added. As the weight percent of the positive electrode active material particles 10P is smaller, the thickness of the layer of the nanoparticles 20P ′ adsorbed on the surface of the positive electrode active material particles 10P increases, and the weight of the positive electrode active material particles 10P is increased. As the percentage increases, the opposite can be true.

Thereafter, the dispersion solution DL is stirred to form intermediate particles in which the nanoparticles 20P ′ are adsorbed on the positive electrode active material particles 10P and obtained (S30). As the nanoparticles 20P ′ are physically and / or chemically adsorbed to the surfaces of the positive electrode active material particles 10, the intermediate particles may be formed in the dispersion solution DL.

In order to accelerate this adsorption process and prevent precipitation of the intermediate particles, a stirring process may be performed within a range of 20 minutes to 4 hours. In some embodiments, ultrasonic waves may be irradiated into the dispersion solution DL using an ultrasonic wave generator such as an ultrasonic probe to improve dispersibility.

The dispersion solution (DL) can then be filtered and / or dried to afford the intermediate particles. If necessary, wetting such as rotor stator mixer, piston homogenizer, gear pump or bit milling, colloid milling and ball milling, in order to homogenize the individualized aggregated intermediate particles and the adsorption amount of the adsorbed nanoparticles 20P '. Grinding or grinding may also be performed.

Subsequently, the obtained intermediate particles are heat treated to sinter the nanoparticles 20P ′ present on the surface of the intermediate particles. The sintering process may be performed in the range of 100 ℃ to 1000 ℃. Preferably, it may be performed in the range of 300 ° C to 600 ° C.

Through the sintering process, the nanoparticles present on the surface of the intermediate particles are bonded to each other through local mass transfer at the contact point or contact surface with other adjacent nanoparticles, so that the particles are continuous as shown in FIG. A conductive barrier layer (BL) having pores (20V) that provide bonds to passivate the positive electrode active material core (10) while providing a migration path for metal ions such as lithium ions for oxidation and reduction of the positive electrode active material core (10). Is formed.

In the solution, the AZO or ATO is added in the form of a precursor, for example, an antimony precursor, a zinc precursor / antimony precursor, and a tin precursor, and by applying thermal energy such as hydrothermal synthesis or microwave using the precursors, the core of the positive electrode active material particles When synthesizing the AZO or ATO on the phase, it is likely to occur in the form of a film or in the form of particles having a non-uniform size, which makes it difficult to form such pores uniformly, and as a result, resistance during charging and discharging of the battery This increasing phenomenon occurs.

However, the present invention uses nanoparticles of AZO or ATO having a uniform average diameter, maintains its dispersion state, adsorbs it to the positive electrode active material core, and then heat-treats the pores derived from the sintered structure of the nanoparticles. The barrier layer BL may be formed. As a result, the growth mechanism of the particles, such as Oswald life, which occurs in the synthesis method is not expressed, and dense membranes and pores derived from the nanoparticles of uniform AZO or ATO can be obtained. In addition, since AZO or ATO nanoparticles that have already been completed and have a uniform size can be used as they are, an economical process for producing a positive electrode active material is advantageous in that it does not require additives such as temperature control or surfactant for controlling the size of the particles. Can be obtained.

The present invention also provides a secondary battery using a cathode, an anode, a separator for separating these electrodes, and optionally a non-aqueous electrolyte, using the cathode active material described above, as is well known in the art. In some embodiments, the cathode active material may be mixed with a binder to be provided on a current collector to form a cathode. For example, the cathode active material mixed with the binder may be directly coated on a current collector such as aluminum or cast on a separate support, and then the film obtained by peeling from the support may be laminated on the current collector to provide a cathode. It may be. In this case, the active material composition may further contain a conductive material such as carbon black when necessary, and aluminum may be used as the current collector, but is not limited thereto.

The binder is vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate (polymethylmethacrylate) , Polymeric materials such as polytetrafluoroethylene (PTFE), styrenebutadiene rubber (SBR), and ethylene-propylene-diene copolymer (EPDM). In another embodiment, the binder may be another polymeric material, petroleum pitch, coal tar having conductivity, but the present invention is not limited thereto.

Since the conductive barrier layer of the cathode active material may serve as a conductive material, a conductive path may be secured between the particulate cathode active materials in physical contact with each other. Optionally, a conductive material may be further added to the anode. The conductive material may be, for example, carbon black and ultra fine graphite particles, fine carbon such as acetylene black, and nano metal particle paste.

The anode is a carbon-based material, for example, low crystalline carbon, such as soft carbon or hard carbon, or natural graphite, Kish graphite, pyrolytic carbon, liquid crystal High-temperature calcined carbon such as mesophase pitch based carbon fiber, meso-carbon microbeads, mesophase pitches, petroleum or coal tar pitch derived cokes It may be provided using a negative electrode active material such as crystalline carbon. In another embodiment, the negative electrode active material is a monomagnetic field such as silicon, germanium, tin, lead, antimony, bismuth, zinc, aluminum, iron and cadmium, and intermetallic compounds thereof, which have a high capacity of absorbing and releasing lithium ions. (intermetallic compound), or an oxide-based material may be included.

The separator may be, for example, a polymer microporous membrane, a woven fabric, a nonwoven fabric, a ceramic, an intrinsic solid polymer electrolyte membrane, a gel solid polymer electrolyte membrane, or a combination thereof. The intrinsic solid polymer electrolyte membrane may include, for example, a linear polymer material or a crosslinked polymer material. The gel polymer electrolyte membrane may be, for example, a combination of any one of a plasticizer-containing polymer containing a salt, a filler-containing polymer, or a pure polymer. The solid electrolyte layer is, for example, polyethylene, polypropylene, polyimide, polysulfone, polyurethane, polyvinyl chloride, polystyrene, polyethylene oxide, polypropylene oxide, polybutadiene, cellulose, carboxymethyl cellulose, nylon, polyacryl Ronitrile, polyvinylidene fluoride, polytetrafluoroethylene, copolymer of vinylidene fluoride and hexafluoropropylene, copolymer of vinylidene fluoride and trifluoroethylene, vinylidene fluoride and tetrafluoroethylene Copolymers of polymethyl acrylate, polyethyl acrylate, polyethyl acrylate, polymethyl methacrylate, polyethyl methacrylate, polybutyl acrylate, polybutyl methacrylate, polyvinylacetate, and polyvinyl alcohol Made of any one or a combination thereof It may include a polymer matrix, additives and the electrolyte. The materials listed with respect to the above-mentioned separators are exemplary, and are easy to change shape as a separator, excellent mechanical strength, do not tear or crack in deformation of the electrode structure, having any suitable electronic insulation and excellent ion conductivity The material can be selected. The separator may be a single layer film or a multilayer film, and the multilayer film may be a laminate of the same single film or a stack of single film formed of different materials. For example, the laminate may have a structure including a ceramic coating film on the surface of a polymer electrolyte film such as polyolefin. The electrolyte may be an organic carbonate solution or a mixture of a lithium compound mixed with the organic carbonate solution as a non-aqueous electrolyte. The organic carbonate may be an organic solvent such as ethylene carbonate (EC), dimethyl carbonate (DMC) or diethyl ether (DEE), and the present invention is not limited thereto. The organic carbonate is aprotic and has a high polarity. Other organic solvents having a high dielectric constant may be applied. The lithium compound may be selected from materials having good solubility and chemical stability such as Li (CR ₃ SO ₂ ) ₂ N, LiAsF ₆ , LiPF ₆ or LiBF ₄ .

A battery made of the above materials may be selected in various sizes and shapes to adjust the capacity of the battery. For example, three-dimensional packaging may be provided by a method such as stacking, bending and / or winding to provide a battery having various volumes and shapes such as a cylindrical battery, a square battery and a coin-type battery or a flexible battery.

Hereinafter, the present invention will be described in more detail with reference to more specific experimental examples. The following disclosure is for illustrative purposes only and should not be construed as limiting the invention thereto.

< Example  1>

< Example  1-1> AZO Conductivity Barrier layer  Preparation of a positive electrode active material comprising

ZnO.Sb ₂ O ₃ nanoparticles having a molar ratio of 1: 1 in zinc oxide and antimony oxide were used as nanoparticles of AZO for forming the conductive barrier layer. The nanoparticles of the AZO have an average diameter of 15 nm selected within the range of 1 nm to 200 nm, with a standard deviation of about 2.

Nanoparticles of the AZO were added to methanol to form a dispersion solution. 3A is a transmission electron microscope image showing nano-sized particles (AZO) of AZO dispersed in a dispersion solution. Referring to FIG. 3A, it can be seen that in the dispersion solution, nanoparticles of AZO are evenly dispersed in the dispersion solution without aggregation.

To 2 g of the nanoparticle dispersion solution thus formed, LiCoO ₂ particles as a cathode active material were added at 100 wt%, that is, 2 g based on 100 wt% of the nanoparticle dispersion solution, followed by stirring for 1 hour. Thereafter, the dispersion solution was filtered to obtain intermediate particles having nanoparticles of AZO adsorbed onto the core of LiCoO ₂ particles. Thereafter, the intermediate particles were heat-treated at 400 ° C. for 5 hours to sinter AZO nanoparticles adsorbed on the surface of the cathode active material, thereby obtaining a LiCoO ₂ cathode active material having an AZO conductive barrier layer formed on the surface thereof.

3B is a transmission electron microscope image showing a cross section of a conductive barrier layer of AZO nanoparticles (AZO) formed on an active material of LiCoO ₂ . Referring to FIG. 3B, it can be seen that an AZO conductive barrier layer (region indicated by a red dotted line) having a thickness of about 30 nm is formed.

< Example  1-2> anode and battery manufacturing

AZO coated LiCoO ₂ obtained in Example 1-1 The positive electrode active material, the carbon black conductive material, and the polyvinylidene fluoride (PVdF) binder were mixed in a weight ratio of 95: 2: 3, and a positive electrode slurry was prepared using an N-methyl pyrrolidone (NMP) solvent. The prepared positive electrode slurry was applied to an aluminum foil, dried at 130 ° C. for 2 hours to prepare a cathode, and then subjected to a roll press.

As the negative electrode active material, natural graphite, carbon black as the conductive material, and styrene-butadiene rubber (SBR) as the binder were mixed in a 93: 1: 6 weight ratio to prepare a negative electrode slurry. The negative electrode slurry was applied to a copper foil and dried at 110 ° C. for 2 hours to produce an anode, followed by roll press.

A polyethylene separator (available from Donnen, F20BHE, thickness = 20 μm) was applied between the positive electrode and the negative electrode prepared in Example 1-1, and an electrolyte (1 mol of lithium hexafluorophosphate (LiPF6) and ethylene Carbonate (EC) / dimethyl carbonate (DMC = 1/1 volume ratio) was injected to finally produce a coin cell.

< Example  2>

LiCoO2 including a conductive barrier layer of AZO in the same manner as in Example 1 except that nanoparticles of AZO having a molar ratio of zinc oxide (ZnO) to antimony oxide (Sb ₂ O ₃ or Sb ₂ O ₅ ) were used. A positive electrode active material was prepared.

A coin battery was manufactured using the prepared cathode active material.

< Example  3> ATO Conductivity Barrier layer  Preparation of positive electrode active material and battery comprising

SnO ₂ · Sb 1 the molar ratio of the ₂ O _3: 1 of SnO ₂ · Sb and the LiCoO ₂ positive electrode of the ATO particles in the same manner as in Example 1, coating, except for using the nanoparticles of ATO represented by ₂ O ₃ An active material was prepared.

The nanoparticles of the ATO have an average diameter of 5 nm selected in the range of 1 nm to 200 nm, with a standard deviation of about 2.

Methanol was used as a dispersion solvent, and the ATO nanoparticles were added at a ratio of 1% by weight to 100% by weight of methanol. 4A is a transmission electron microscope image showing nano-sized particles (ATO) of ATO dispersed in a dispersion solution. Referring to FIG. 4A, it can be seen that in the dispersion solution, nanoparticles (ATO) of ATO are uniformly dispersed without aggregation.

Thereafter, ₂ g of LiCoO ₂ particles were added to ₂ g of the dispersion solution, followed by stirring for 1 hour and heat treatment at 400 ° C. to obtain cathode active material particles coated with ATO nanoparticles.

4B is a transmission electron microscope image (SEM) showing a cross section of a conductive barrier layer of ATO nanoparticles (ATO) formed on an active material core of LiCoO ₂ . Referring to FIG. 4B, it can be seen that a conductive barrier layer (region indicated by a red dotted line) having a thickness of about 30 nm is formed.

Using the positive electrode active material particles prepared as described above, a coin battery was manufactured in the same manner as in Example 1.

< Example  4> ATO Nanoparticles coated LiCoO ₂  of  Manufacture of positive electrode active material

A positive electrode active material was prepared in the same manner as in Example 3, except that nanoparticles of ATO having a molar ratio of antimony oxide (Sb ₂ O ₃ or Sb ₂ O ₅ ) / tin oxide (SnO ₂ ) were used. Was used to prepare a coin battery.

< Comparative Example 1 >

As Comparative Example 1, unlike Examples 1 to 4, a cathode was formed using the cathode active material itself, that is, LiCoO ₂ particles not coated with nanoparticles, and a coin battery was manufactured using the same.

5 is a scanning electron microscope image showing a LiCoO ₂ positive electrode active material according to Comparative Example 1. FIG. The LiCoO ₂ positive electrode active material of FIG. 5 has an average diameter of about 5 μm.

< Experimental Example > Charge / discharge characteristics evaluation

For the coin batteries according to Examples 1 to 4 and Comparative Example 1, charge and discharge characteristics were evaluated using a charge and discharge battery capable of constant current / potential control. The discharge (reduction) end voltage was fixed at 3.0 V (vs. Li / Li +) and the charge end voltage was fixed at 4.4 V (vs. Li / Li +).

Figure 6a is a graph showing the discharge performance according to the rate of the coin battery according to Example 1. The discharge characteristics according to the rate are 0.2 C-rate (0.46 mAcm ^-2 ), 0.5 C-rate (1.15 mAcm ^-2 ), 1.0 C-rate (2.31 mAcm ^-2 ) and 2.0 C-rate ( 4.62 mA · cm ⁻² ). Referring to FIG. 6A, it can be seen that the battery of Example 1 exhibited characteristics suitable for high output discharge with a discharge capacity of 2.0 C-rate compared to 0.2 C-rate of 77.8%. Although not shown, the same result was confirmed also in the case of Example 2.

Figure 6b is a graph showing the discharge performance according to the rate for the coin battery containing the active material coated ATO nanoparticles according to Example 3. Similarly, the discharge characteristics according to the rate were 0.2 C-rate, 0.5 C-rate, 1.0 C-rate and 2.0 C-rate. Referring to FIG. 6B, the battery of Example 3 showed a discharge capacity of 2.0 C-rate compared to 0.2 C-rate, which corresponds to 90.3%, and exhibited characteristics suitable for high output discharge. Although not shown, the same result was confirmed also in the case of Example 4.

6C is a graph showing the discharge performance according to the rate rate for the coin battery according to Comparative Example 1. Similarly, the discharge characteristics according to the rate were 0.2 C-rate, 0.5 C-rate, 1.0 C-rate and 2.0 C-rate. Referring to FIG. 6C, as the rate increases, the discharge capacity is remarkably decreased, and the discharge capacity of 2.0 C-rate compared to 0.2 C-rate may be lowered to a level of 55.1%.

6A to 6C, it can be seen that in the case of the active material according to the embodiment of the present invention, the conductive barrier layer formed by the AZO and ATO nanoparticles contributes to improving durability of the cathode active material against overvoltage as the discharge current increases. have. In addition, in the case of the charging performance according to the rate, Examples 1 to 4, respectively, the charging capacity of 2.0 C-rate compared to 0.2 C-rate it was confirmed that the charge and discharge of high speed and high efficiency is possible.

< Experimental Example > Life Characterization

7A is a cycle characteristic of the coin battery according to Example 1, Example 2 and Comparative Example 1, Figure 7b and 7c are graphs showing the cycle characteristics of the coin battery according to Examples 3, 4 and Comparative Example 1. In these graphs, the red lines are the measurement results for Examples 1 to 4, and the black lines are the measurement results for Comparative Example 1.

Referring to FIG. 7A, in the case of a coin battery according to Comparative Example 1, the capacity at 100 charge / discharge cycles is reduced to less than 50% of the initial capacity at 0.5 C-rate. In contrast, the coin battery according to Example 1 of the present invention exhibited 75% or more of its initial capacity even after 100 charge / discharge cycles.

Referring to FIGS. 7B and 7C, as the rate increases to 1.0 C-rate and 2.0 C-rate, in the case of the coin battery according to Comparative Example 1, the initial capacity decreases remarkably, but the coin battery according to Example 3 In the case of, there is almost no decrease in initial capacity even after 100 times of charging and discharging, and thus it can be confirmed that it is suitable for a high output battery. In addition, although not shown, the same result was confirmed also in the case of Examples 2 and 4.

In general, considering that the decrease in capacity as the cycle of charging and discharging proceeds is caused by resistance at the interface between the positive electrode active material and the electrolyte and decomposition by-products of the electrolyte, deterioration of the cycle characteristics according to Comparative Example 1 results in the positive electrode active material LiCoO ₂ It is believed that lithium ions are consumed by the collapse of the structure due to the change of crystal lattice and reaction with the electrolyte.

However, in Examples 1 and 3, irrespective of C-rate, it exhibits excellent cycle characteristics, in which the conductive barrier layer of AZO or ATO nanoparticles effectively passivates the positive electrode active material core from the electrolyte, thereby improving the structural stability of the positive electrode active material. Because it improves. In addition, despite the fact that AZO or ATO itself does not carry lithium, the smooth flow of lithium ions can be maintained during the charging / discharging cycle, indicating that there is almost no decrease in porosity of pores formed in the conductive barrier layer. Able to know.

< Experimental Example > Impedance Measurement

8A and 8B are graphs showing impedance values after the initial charge and discharge (1 cycle) and after 100 cycles of the coin batteries according to Examples 1 and 3, respectively, and FIG. 8C is an initial view of the coin battery according to Comparative Example 1; It is a graph showing impedance values after charge and discharge (1 cycle) and after 100 cycles.

Referring to FIG. 8A, in the case of the coin battery according to Embodiment 1, the impedance is increased, but the increase of the impedance is limited to less than 60 Ω. In addition, referring to FIG. 8B, in the case of the coin battery according to the third embodiment, it may be confirmed that there is almost no impedance change due to the cycle change.

From these results, it can be seen that the conductive barrier layer made of ATO prepared in Example 3 has more optimized life characteristics than the conductive barrier layer made of AZO prepared in Example 1. However, referring to FIG. 8C, in the coin battery according to Comparative Example 1, the impedance rapidly increases after 100 cycles and has a value of 500 Ω or more.

From the results of the impedance measurement, it can be seen that the conductive barrier layer is effective in suppressing the addition reaction that generates a large resistance component in the battery according to the charge / discharge cycle of the battery. Also, the pores formed in the conductive barrier layer are not reduced during the charge / discharge cycle, and the flow of lithium ions can be maintained smoothly.

< Experimental Example > Cyclic voltage scan

Figure 9a is a graph showing the measurement results by the cyclic voltage scanning method after the initial charge and discharge (1 cycle) and after 100 cycles of the coin battery according to Example 1, Figure 9b is the initial charge of the coin battery according to Comparative Example 1 • A graph showing measurement results according to the cyclic voltage scanning method after discharge (1 cycle) and after 100 cycles.

The difference between the oxidation peak and the reduction peak (= ΔV) is affected by the intercalation / deintercalation process of lithium ions. Therefore, the greater the difference, the more severe the polarization of the electrode.

9A and 9B, the coin battery according to Example 1 has a value lower than the ΔV value of the coin battery according to Comparative Example 1 both after initial charge and discharge (one cycle) and after 100 cycles. . Therefore, it can be seen that the polarization phenomenon of the cathode prepared according to Example 1 was significantly reduced compared to Comparative Example 1 in the course of the charging and discharging cycle, and although not shown, the same as in Example 1 also in Example 2 It was confirmed that the results of

< Example  5> ATO Conductivity Barrier layer  Including positive electrode active material and battery manufacturing

< Example  5-1> ATO Conductivity Barrier layer  Containing Li [ Ni _{0 .6} Co _{0 .2} Mn _{0 .2} ] O ₂ Cathode active material

Instead of the positive electrode active material of _{LiCoO 2 Li [Ni 0 .6 Co} 0 .2 Mn 0 .2] O , and antimony oxide in the same manner as in Example 4 except for using the positive electrode active material ₂ (Sb ₂ O ₃ or Sb ₂ O ₅₎ / tin oxide (SnO ₂₎ the Li molar ratio of the coating of 0.057 ATO nanoparticles in the same manner as _{[Ni 0 .6 Co 0 .2 Mn} 0 .2] O 2 in example 1 to prepare a cathode active material, and To prepare a positive electrode and a battery.

< Comparative Example  2>

In the same manner as in Comparative Example 1 by using the _{ATO Li [Ni 0 .6 Co 0} .2 Mn 0 .2] O 2 positive active material is not coated with the nanoparticles to prepare a coin battery.

< Experimental Example > SEM  Photo measurement

Comparative Example 2 Li are not coated with the ATO nanoparticles _{[Ni 0 .6 Co 0 .2 Mn} 0 .2] O ₂ positive active material, and the ATO nanoparticles of Example 5 Coating of Li [Ni _{0 .6 0 0 .2 .2} Mn Co] O ₂ measuring SEM picture relative to the positive electrode active material and the results are shown in Figure 10a and Figure 10b. Comparing the transmission electron microscope image of Figure 10a and Figure 10b it can be seen that the ATO nanoparticles are coated on the surface of the positive electrode active material of Figure 10b.

< Experimental Example > Charge / discharge characteristics evaluation

For the coin batteries prepared in Example 5 and Comparative Example 2, charging and discharging characteristics were evaluated using a charger and a charger capable of constant current / potential control. The discharge (reduction) end voltage was fixed at 3.0 V (vs. Li / Li +) and the charge end voltage was fixed at 4.3 V (vs. Li / Li +). In addition, life characteristic evaluation was measured at 55 degreeC.

11A is a graph showing the discharge performance according to the rate of the coin battery according to Example 5. The discharge characteristics according to the rate are 0.1 C-rate (0.22 mAcm ^-2 ), 1 C-rate (2.24 mAcm ^-2 ), 5.0 C-rate (11.2 mAcm ^-2 ) and 10 C-rate ( 22.4 mA · cm ⁻² ).

11A and 11B, it can be seen that the battery of Example 5 has improved high output characteristics compared to the battery of Comparative Example 2.

< Experimental Example > Life Characterization

12 is a result of specifying the life characteristics of the coin battery according to Example 5 and Comparative Example 2. In FIG. 12, red lines are the measurement results for Example 5, and black lines are the measurement results for Comparative Example 2. FIG. Referring to FIG. 12, at 55 ° C. and 1.0 C-rate, the capacity of the coin battery according to Comparative Example 2 is reduced to less than 50% of the initial capacity after 16 charge / discharge cycles. However, in the coin battery according to Example 5, even after 30 charge / discharge cycles, 60% or more of the initial capacity can be obtained.

According to the positive electrode active material described above, the lifespan can be improved by securing a stable interface between the electrolyte and the positive electrode active material and the movement path of the metal ions due to the pores during the cycle by the conductive barrier layer, and also improve the electronic conductivity. As a high efficiency and high output battery can be obtained, it can be applied to a medium-large battery for power source or electric power storage of an automobile.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It will be clear to those who have knowledge.

Claims (15)

A positive electrode active material core; And
It is a cathode active material for a lithium secondary battery comprising a conductive barrier layer formed of any one or more selected from the group consisting of antimony zinc oxide, antimony tin oxide, and combinations thereof on the cathode active material core,
The conductive barrier layer includes a pore for communicating the positive electrode active material core from the surface of the positive electrode active material.
The method of claim 1,
The antimony zinc oxide is a positive electrode active material comprising any one or a mixture of compounds represented by the following formula (1) or (2).
(ZnO ₂ ) x (Sb ₂ O ₃ ) y, x + y = 1, 0 <y / x≤2
(ZnO ₂ ) x (Sb ₂ O ₅ ) y, x + y = 1, 0 <y / x≤2
The method of claim 1,
The antimony tin oxide is a positive electrode active material comprising any one or a mixture of compounds represented by the following formula (3) or (4).
(SnO ₂ ) x (Sb ₂ O ₃ ) y, x + y = 1, 0 <y / x≤2
(SnO ₂ ) x (Sb ₂ O ₅ ) y, x + y = 1, 0 <y / x≤2
The method of claim 1,
The conductive barrier layer includes a sintered body of nanoparticles of the antimony zinc oxide or antimony tin oxide, wherein the pores are provided by the space between the adjacent nanoparticles.
5. The method of claim 4,
The nanoparticles are cathode active material, characterized in that having an average particle diameter in the range of 1 nm to 200 nm.
5. The method of claim 4,
Particle diameter of the nanoparticles is a positive electrode active material, characterized in that it has a standard deviation within the range of 1 nm to 50 nm.
5. The method of claim 4,
The thickness of the conductive barrier layer is a positive electrode active material, characterized in that in the range of 2 to 500 particle layer of the nanoparticles.
5. The method of claim 4,
The thickness of the conductive barrier layer is a positive electrode active material, characterized in that 2 nm to 500 nm.
The method of claim 1,
The positive electrode active material core is _{Li a A 1 - b X b} D 2 (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5); Li _a A _1-b X _b O _{2 -c} D _c (0.90? A? 1.8, 0? B? 0.5, 0? C? 0.05); Li _a E _{1 - b} X _b O _{2 - c} D _c (0.90? A? 1.8, 0? B? 0.5, 0? C? 0.05); _{Li a E 2 - b X b} O 4 - c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); _{Li a Ni 1 -b- c Co b} X c D α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 <α ≤ 2); _{Li a Ni 1 -b- c Co b} X c O 2 -α Т α ((0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 <α <2); Li a Ni 1 - _{b- c} Co _b X _c O _{2 -α} Т ₂ (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 <α <2); Li _a Ni _{1 -b- c} Mn _b X _c D _α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 <α ≤ 2); Li _a Ni _{1 -b- c} Mn _b X _c O _{2 -α} Т _α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 <α <2); Li _a Ni _{1 -b- c} Mn _b X _c O _{2 -α} Т ₂ (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 <α <2); Li _a Ni _b E _c G _d O ₂ (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ Li _a Ni _b Co _c Mn _d GeO ₂ (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0.001 ≤ e ≤ 0.1); Li _a NiG _b O ₂ (0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li _a CoG _b O ₂ (0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li _a MnG _b O ₂ (0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li _a Mn ₂ G _b O ₄ (0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li _a Mn _{1 - g} G _g PO ₄ (0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5); QO ₂ ; QS ₂ ; LiQS ₂ ; LiZO ₂ ; LiNiVO ₄ ; Li _(3-f) J ₂ (PO ₄ ) ₃ (0 ≤ f ≤ 2) Li _(3-f) Fe ₂ (PO ₄ ) ₃ (0 ≦ f ≦ 2); LiFePO _4; FeF ₃ ; Li ₅ Fe _1-x X _x O _4-y T _y (0 ≦ x ≦ 1, 0 ≦ y ≦ 1); AV ₂ O ₆ ; Li _x V ₃ O ₈ (0 ≦ x ≦ 1); Li _x V ₂ O ₅ (0 ≦ x ≦ 1); Li _x AVO ₄ (0 ≦ x ≦ 1); JRu ₂ O ₄ ; Li ₂ RuO ₃ ; MoO _x (2.9 <x <3.1); Mo _x Ru _{1 - x} O ₂ (0 ≦ x ≦ 1); LiG _B O ₃ ; LiFeSO ₄ F; Fe ₂ (SO ₄ ) ₃ ; Li ₂ GSiO ₄ ; J ₂ GP ₂ O ₇ ; LiFePO ₄ F; LiTiPO ₄ F; LiVPO ₄ O; LiVPO ₄ F; J ₃ V ₂ (PO ₄ ) ₂ F ₃ ; J ₃ V ₂ (PO ₄ ) ₃ ; J ₂ XPO ₄ F; Li ₂ FeSiPO ₄ ; LiX ₂ PO ₄ ; Li _x Mn _{2 - y} X _y O _{4 - z} T _z (0.8 ≦ x ≦ 1.8, 0 ≦ y ≦ 0.6, 0 ≦ z ≦ 0.6); (A is selected from the group consisting of Ni, Co, Mn, and combinations thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, Ti, Zr, rare earth elements and combinations thereof D is selected from the group consisting of O, F, S, P and combinations thereof; E is selected from the group consisting of Co, Mn and combinations thereof; T is F, S, P and G is selected from the group consisting of a combination thereof; G is selected from the group consisting of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V and combinations thereof; J is Li, Na and combinations thereof Q is selected from the group consisting of Ru, Mo, Mn, Ti, V and combinations thereof, Z is selected from the group consisting of Cr, V, Fe, Sc, Y and combinations thereof; J is selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, and combinations thereof) or any combination thereof. A positive electrode active material, characterized in that.
A lithium secondary battery comprising the cathode active material according to claim 1.
Antimony-containing zinc oxide (AZO) nanoparticles represented by Formula 1 or 2 and antimony tin oxide represented by Formula 3 or 4 in any one or two or more dispersed solvents of alcohol-based, ether-based and ketone-based solvents. adding one or more particles selected from the group consisting of nanoparticles of antimony-containing tin oxide (ATO) to form a dispersion solution;
Providing positive electrode active material particles in the dispersion solution;
Stirring the dispersion solution including the cathode active material particles to form intermediate particles having the nanoparticles adsorbed on the cores of the cathode active material particles; And
Heat treating the obtained intermediate particles to sinter the nano-sized particles to form a conductive barrier layer having pores on the core of the positive electrode active material particles;
Method for producing a positive electrode active material according to claim 1 comprising a.
The method of claim 11,
In the forming of the dispersion solution, the nanoparticles are prepared in a proportion of 0.1 wt% to 50 wt% based on 100 wt% of the dispersion solution.
The method of claim 11,
In the providing of the cathode active material particles, the cathode active material particles are added in a ratio of 10% by weight to 200% by weight based on 100% by weight of the dispersion solution to which the nanoparticles are added. .
The method of claim 11,
The alcohol solvent is methanol, ethyl alcohol, methyl alcohol, glycerol, propylene glycol, isopropyl alcohol, isobutyl alcohol, polyvinyl alcohol, cyclohexanol, octyl alcohol, decanol, hexatecanol, ethylene glycol, 1.2- One or a mixture of octanediol, 1,2-dodecanediol and 1,2-hexadecanediol,
The ether solvent is acetone, hexane, octyl ether, butyl ether, hexyl ether, benzyl ether, phenyl ether, decyl ether, ethyl methyl ether, dimethyl ether, diethyl ether, diphenyl ether, tetrahydrofuran (THF), 1,4-dioxane, polyethylene glycol (PEG), polypropylene glycol (PPG), polytetramethylene glycol (PTMG) and polyoxymethylene (POM), polytetrahydrofuran or mixtures thereof
The ketone solvent is methyl ethyl ketone, cyclohexanone, 4-hydroxy-4-methyl-2-pentanone, methyl-n-propyl ketone, methyl-n-butyl ketone, methyl-n-amyl ketone, 2 A method for producing a positive electrode active material, characterized in that it comprises any one or a mixture thereof.
The method of claim 11,
The heat treatment is a method of producing a positive electrode active material, characterized in that performed in the range of 100 ℃ to 1000 ℃.

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