JP7024083B2 - Positive electrode, non-aqueous electrolyte battery, and battery pack - Google Patents

Description

Embodiments of the present invention relate to positive electrodes, non-aqueous electrolyte batteries, and battery packs.

When the non-aqueous electrolyte battery is in a high charge state, self-discharge occurs on the surface of the electrode, which causes a decomposition reaction of the electrolytic solution. For example, an oxidation reaction occurs on the surface of the positive electrode to generate an oxidizing gas (for example, carbon dioxide). When gas is generated, the battery expands and the internal resistance rises. There is a problem that such gas generation can be a factor that lowers the safety of the battery.

Japanese Unexamined Patent Publication No. 2010-23201 Japanese Unexamined Patent Publication No. 2016-48671

An object to be solved by the present invention is to provide a positive electrode in which gas generation is suppressed, and a non-aqueous electrolyte battery and a battery pack containing the positive electrode.

According to the embodiment, a positive electrode is provided. The positive electrode includes a positive electrode active material-containing layer. The positive electrode active material-containing layer contains a positive electrode active material. The positive electrode active material contains a lithium manganese composite oxide and lithium cobalt oxide. The positive electrode active material-containing layer has a surface in which a plurality of peaks of the binding energy of Al in the X-ray photoelectron spectroscopic spectrum are in the range of 70 eV or more and 78 eV or less. The positive electrode active material-containing layer satisfies the relational expression of 0 <H / (G + H) ≦ 0.1. Here, G is the weight ratio of the lithium manganese composite oxide in the positive electrode active material. H is the weight ratio of lithium cobalt oxide in the positive electrode active material. The positive electrode further satisfies the following formula (2).
0.3 ≤ (BC) / (AC) ≤ 2 (2)
Here, A is the maximum peak height of the X-ray photoelectron spectrum within the range of 70 eV or more and less than 75 eV of the binding energy of Al, and B is the said above within the range of 75 eV or more and 78 eV or less of the binding energy of Al. It is the maximum peak height of the X-ray photoelectron spectrum, and C is the average peak height of the X-ray photoelectron spectrum within the range of 65 eV or more and less than 70 eV of the binding energy of Al.
According to another embodiment, a non-aqueous electrolyte battery is provided. The non-aqueous electrolyte battery includes the positive electrode, the negative electrode, and the non-aqueous electrolyte of the embodiment.
According to other embodiments, battery packs are provided. The battery pack comprises the non-aqueous electrolyte battery of the embodiment.

FIG. 1 is a partially cutaway perspective view of an example of a non-aqueous electrolyte battery according to a second embodiment. FIG. 2 is an enlarged cross-sectional view of part A of the non-aqueous electrolyte battery shown in FIG. FIG. 3 is an exploded perspective view of another example of the non-aqueous electrolyte battery according to the second embodiment. FIG. 4 is an exploded perspective view of an example of the battery pack according to the third embodiment. FIG. 5 is a block diagram showing an electric circuit of the battery pack shown in FIG. FIG. 6 is one XPS spectrum of the positive electrode active material-containing layer of the positive electrode of Example 7. FIG. 7 is another XPS spectrum of the positive electrode active material-containing layer of the positive electrode of Example 7.

Hereinafter, embodiments will be described with reference to the drawings. It should be noted that the same reference numerals are given to the common configurations throughout the embodiments, and duplicate description will be omitted. In addition, each figure is a schematic diagram for explaining the embodiment and promoting its understanding, and the shape, dimensions, ratio, etc. are different from those of the actual device, but these are described below and known techniques. The design can be changed as appropriate by taking into consideration.

(First Embodiment)
According to the first embodiment, a positive electrode is provided. The positive electrode includes a positive electrode active material-containing layer. The positive electrode active material-containing layer contains a positive electrode active material. The positive electrode active material contains a lithium manganese composite oxide and lithium cobalt oxide. The positive electrode active material-containing layer has a surface in which a plurality of peaks of the binding energy of Al in the X-ray photoelectron spectroscopic spectrum are in the range of 70 eV or more and 78 eV or less. The positive electrode active material-containing layer satisfies the following formula (1).

0 <H / (G + H) ≤ 0.1 (1)
Here, G is the weight ratio of the lithium manganese composite oxide in the positive electrode active material. H is the weight ratio of lithium cobalt oxide in the positive electrode active material.

The positive electrode active material containing the lithium manganese composite oxide and lithium cobalt oxide comes into contact with a compound generated by the reaction of a non-aqueous electrolyte and a trace amount of water, which is an unavoidable impurity, such as hydrofluoric acid (HF). For example, it generates gases such as hydrogen and carbon monoxide. Due to such gas generation, for example, in a non-aqueous electrolyte battery provided with a positive electrode containing the above-mentioned positive electrode active material, the internal resistance increases due to the expansion of the non-aqueous electrolyte battery. This may reduce the safety of the non-aqueous electrolyte battery.

Therefore, the positive electrode active material-containing layer has a surface in which a plurality of peaks of the binding energy of Al in the X-ray photoelectron spectroscopic spectrum are in the range of 70 eV or more and 78 eV or less. This surface can prevent the positive electrode active material from coming into direct contact with the non-aqueous electrolyte and the compound generated by the reaction of water. As a result, gas generation can be suppressed.

Further, the positive electrode active material-containing layer satisfies the formula (1). Since the positive electrode active material-containing layer contains a predetermined amount of lithium cobalt oxide capable of absorbing gas, the generated gas can be absorbed.

Therefore, the positive electrode active material-containing layer has a surface in which a plurality of peaks of the binding energy of Al in the X-ray photoelectron spectroscopic spectrum are in the range of 70 eV or more and 78 eV or less, and gas generation is generated by satisfying the formula (1). It can be suppressed.

It is desirable that the positive electrode active material-containing layer has a surface in which a plurality of peaks of the binding energy of Al in the X-ray photoelectron spectroscopy spectrum are at least one in the range of 70 eV or more and less than 75 eV and in the range of 75 eV or more and 78 eV or less. ..

Since the positive electrode active material-containing layer having a surface satisfying this has a surface containing a bond between Al and O and a bond between Al and F, it is generated by the reaction between the positive electrode active material and the non-aqueous electrolyte and water. It is more effective in preventing direct contact with the compound. As a result, gas generation can be suppressed.

It is desirable that the positive electrode satisfies the following formula (2).

0.3 ≤ (BC) / (AC) ≤ 2 (2)
Here, A is the maximum peak height of the X-ray photoelectron spectroscopy spectrum in the range of 70 eV or more and less than 75 eV of the binding energy of Al. B is the maximum peak height of the X-ray photoelectron spectroscopy spectrum within the range of 75 eV or more and 78 eV or less of the binding energy of Al. C is the average peak height of the X-ray photoelectron spectroscopy spectrum in the range of 65 eV or more and less than 70 eV of the binding energy of Al.

Since the positive electrode active material-containing layer having a surface satisfying this has a surface containing a bond between Al and O and a bond between Al and F at a predetermined ratio, the positive electrode active material, the non-aqueous electrolyte, and the water content are contained. The effect of preventing direct contact with the compound generated by the reaction of the above is even higher. As a result, gas generation can be suppressed.

It is desirable that the positive electrode satisfies the following formula (3).

0.004 ≤ (BC) / (DE) ≤ 0.04 (3)
Here, D is the maximum peak height of the X-ray photoelectron spectroscopic spectrum in the range of 638 eV or more and 645 eV or less of the binding energy of Mn. E is the average peak height of the X-ray photoelectron spectroscopy spectrum in the range of 635 eV or more and less than 638 eV of the binding energy of Mn.

The positive electrode active material-containing layer having a surface satisfying this has a surface containing the bond of Al and F with respect to the bond of Mn and O at a predetermined ratio. Therefore, it is possible to prevent the positive electrode active material from directly contacting the non-aqueous electrolyte and the compound generated by the reaction of water without significantly reducing the conductivity of the Li ion of the positive electrode. As a result, gas generation can be suppressed.

The composition formula of the lithium manganese composite oxide is LiMn _2-x M _x O ₄ , where the subscript x is in the range of 0.1 ≦ x ≦ 0.7, and M is Mg, Ti, Cr, It is desirable that it is at least one metal element selected from the group consisting of Fe, Co, Zn, Al and Ga.

The positive electrode active material-containing layer containing the lithium manganese composite oxide having the above composition and having the above-mentioned surface has an effect of preventing the positive electrode active material from directly contacting the compound generated by the reaction of the non-aqueous electrolyte and water. Is even higher, and the effect of suppressing gas generation is very high. As a result, gas generation can be significantly suppressed.

The positive electrode according to the first embodiment will be described in detail below.

The positive electrode according to the first embodiment includes a positive electrode current collector and a positive electrode active material-containing layer supported on one side or both sides of the positive electrode current collector. The positive electrode active material-containing layer contains a positive electrode active material. Further, the positive electrode active material-containing layer may further contain a conductive agent and a binder.

The positive electrode active material contains a lithium manganese composite oxide and lithium cobalt oxide.

The composition formula of the lithium manganese composite oxide is preferably LiMn _2-x M _x O ₄ . Here, the subscript x is in the range of 0.1 ≦ x ≦ 0.7, and M is at least one metal selected from the group consisting of Mg, Ti, Cr, Fe, Co, Zn, Al and Ga. It is preferably an element. It is more preferable that M is Al. The lithium manganese composite oxide is more preferably having a spinel-type crystal structure.

The composition formula of lithium cobalt oxide is preferably Li _x CoO ₂ . Here, the subscript x is preferably in the range of 0 <x ≦ 1.

The positive electrode active material-containing layer preferably satisfies the following formula.
0 <H / (G + H) ≤ 0.1 (1)
Here, G is the weight ratio of the lithium manganese composite oxide in the positive electrode active material. H is the weight ratio of lithium cobalt oxide in the positive electrode active material.

As described above, the positive electrode active material-containing layer can suppress gas generation by satisfying the formula (1). The reason is described below. When H / (G + H) is larger than 0.1, the amount of lithium cobalt oxide that is weak against high potential is large, and it is considered that the crystal structure of lithium cobalt oxide is destroyed by charging and discharging. Therefore, in addition to not being able to suppress gas generation, the charge / discharge cycle performance deteriorates. When H / (G + H) is 0, that is, when lithium cobalt oxide is not contained in the positive electrode active material, for example, the positive electrode active material cannot absorb the gas inevitably generated by the reaction between the non-aqueous electrolyte and water. , Gas generation cannot be suppressed.

The positive electrode active material is, for example, in the form of particles. When it is in the form of particles, the positive electrode active material may be primary particles or may be secondary particles in which primary particles are aggregated.

The particles of the lithium manganese composite oxide may be either primary particles or secondary particles in which the primary particles are aggregated, but preferably include secondary particles. The average particle size (secondary particle size) of the secondary particles of the lithium manganese composite oxide is preferably 4 μm or more and 15 μm or less.

The lithium cobalt oxide particles may be either primary particles or secondary particles in which the primary particles are aggregated, but it is preferable that the primary particles are the main particles. The average particle size of the primary particles of lithium cobalt oxide particles is preferably 6 μm or more and 12 μm or less.

The type of the positive electrode active material may be one type or two or more types. Further, the positive electrode active material may contain a positive electrode active material other than the lithium manganese composite oxide and lithium cobalt oxide.

The conductive agent can increase the electron conductivity and suppress the contact resistance with the current collector. Examples of the conductive agent include carbon materials such as acetylene black, carbon black, graphite, carbon nanofibers or carbon nanotubes. The type of the conductive agent used may be one type or two or more types.

The binder can bind the active material to the conductive agent. Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluorinated rubber. The type of binder used may be one or more.

The positive electrode active material-containing layer has a surface in which a plurality of peaks of the binding energy of Al in the X-ray photoelectron spectroscopic spectrum are in the range of 70 eV or more and 78 eV or less. This surface can be, for example, a coating formed on the positive electrode active material-containing layer. There may be two or three or more peaks of the binding energy of Al in the range of 70 eV or more and 78 eV or less. Here, the surface of the positive electrode active material-containing layer is the main surface of the positive electrode active material-containing layer facing the surface where the positive electrode active material-containing layer and the positive electrode current collector are in contact with each other, and is in contact with the positive electrode current collector. Represents no main surface.

The positive electrode active material-containing layer preferably has at least one peak in the binding energy of Al in the range of 70 eV or more and less than 75 eV and in the range of 75 eV or more and 78 eV or less. The peak of the binding energy of Al in the range of 70 eV or more and less than 75 eV indicates that the bond between Al and O exists. The peak of the binding energy of Al in the range of 75 eV or more and 78 eV or less indicates that the bond between Al and F exists. There may be one or two or more peaks in the respective ranges of 70 eV or more and less than 75 eV and 75 eV or more and 78 eV or less. The number of peaks present in each range may be the same or different.

As described above, gas generation can be suppressed by having at least one peak in each of the above ranges. This is because the surface of the positive electrode active material-containing layer contains a bond between Al and F, so that contact between the positive electrode active material and the compound generated by the reaction of the non-aqueous electrolyte and water can be avoided. Conceivable.

The positive electrode active material-containing layer preferably satisfies the following formula.
0.3 ≤ (BC) / (AC) ≤ 2 (2)
Here, A is the maximum peak height of the X-ray photoelectron spectroscopy spectrum in the range of 70 eV or more and less than 75 eV of the binding energy of Al. B is the maximum peak height of the X-ray photoelectron spectrum in the range of 75 eV or more and 78 eV or less of the binding energy of Al. C is the average peak height of the X-ray photoelectron spectroscopy spectrum in the range of 65 eV or more and less than 70 eV of the binding energy of Al. The maximum peak height in the range of 70 eV or more and less than 75 eV and in the range of 75 eV or more and 78 eV or less is the spectrum data having the highest peak height in the continuous spectral data within the range of the X-ray photoelectron spectral spectrum. It is the peak height. The average peak height is the peak height obtained by averaging the peak heights of the spectral data of continuous X-ray photoelectron spectroscopy within the range of 65 eV or more and less than 70 eV.

As described above, by satisfying the equation (2), gas generation can be suppressed. The reason is described below. When the value of (BC) / (AC) is 0.3 or more and 2 or less, it is filled because the coating on the surface of the positive electrode active material-containing layer contains an appropriate bond between Al and F. While maintaining the discharge performance, it is possible to suppress the reaction between the compound inevitably generated by the reaction between the non-aqueous electrolyte and water and the positive electrode active material-containing layer. As a result, it is considered that the increase in internal resistance and the generation of gas can be suppressed.

It is more preferable that the positive electrode active material-containing layer satisfies the following formula.
0.004 ≤ (BC) / (DE) ≤ 0.04 (3)
Here, D is the maximum peak height of the X-ray photoelectron spectrum in the range of 638 eV or more and 645 eV or less of the binding energy of Mn. E is the average peak height of the X-ray photoelectron spectrum in the range of 635 eV or more and less than 638 eV of the binding energy of Mn. The peak of the binding energy of Mn in the range of 638 eV or more and 645 eV or less indicates that the bond between Mn and O exists. The maximum peak height in the range of 638 eV or more and 645 eV or less is the peak height of the spectral data having the highest peak height in the continuous spectral data within the range of the X-ray photoelectron spectral spectrum. The average peak height is the peak height obtained by averaging the peak heights of the spectral data of continuous X-ray photoelectron spectroscopy within the range of 635 eV or more and less than 638 eV.

As described above, by satisfying the equation (3), gas generation can be suppressed. The reason is described below. When the value of (BC) / (DE) is 0.004 or more and 0.04 or less, the bond between Mn and O contained in the positive electrode active material-containing layer is on the positive electrode active material-containing layer. There is a sufficient bond between Al and F in the coating film of. This film exhibits the reaction between the compound inevitably generated by the reaction of the non-aqueous electrolyte and water and the positive electrode active material-containing layer while maintaining the ionic conductivity of the Li ion of the positive electrode, that is, the charge / discharge performance. It is thought that it can be suppressed.

The positive electrode current collector is preferably formed of an aluminum foil or an aluminum alloy foil. The average crystal grain size of the aluminum foil and the aluminum alloy foil is preferably 50 μm or less. More preferably, it is 30 μm or less. More preferably, it is 5 μm or less. When the average crystal grain size is 50 μm or less, the strength of the aluminum foil or the aluminum alloy foil can be dramatically increased, the positive electrode can be made denser with a high pressing pressure, and the battery capacity can be increased. Can be made to.

The thickness of the current collector is 20 μm or less, more preferably 15 μm or less. The purity of the aluminum foil is preferably 99% by weight or more. The aluminum alloy is preferably an alloy containing one or more elements selected from the group consisting of magnesium, zinc and silicon. On the other hand, the content of transition metals such as iron, copper, nickel and chromium is preferably 1% by weight or less.

The blending ratio of the positive electrode active material, the conductive agent and the binder is preferably in the range of 80 to 95% by weight of the positive electrode active material, 3 to 18% by weight of the conductive agent, and 2 to 7% by weight of the binder.

The positive electrode active material-containing layer preferably has a porosity of 20% or more and 50% or less. The positive electrode provided with the positive electrode active material-containing layer having such a porosity has a high density and has an excellent affinity with a non-aqueous electrolyte. A more preferable porosity is 25% or more and 40% or less.

The density of the positive electrode active material-containing layer is preferably 2.5 g / cm ³ or more.

Next, a method for measuring the weight ratio of the positive electrode active material represented by G and H in the formula (1) and the X-ray photoelectron spectroscopy for the positive electrode active material-containing layer will be described. First, a method of taking out the positive electrode will be described.

<How to take out the positive electrode>
The battery is completely discharged to set the state of charge (SOC) to 0%. This battery is disassembled, and the positive electrode is cut out by about 2 cm square. The cut positive electrode is immersed in 50 cc (cm ³ ) of ethyl methyl carbonate and left for 1 hour. Then, in order to dry the positive electrode, it is vacuum dried for 1 hour to obtain a measurement sample. The operations up to this point are performed in a glove box with an argon atmosphere.

<Measurement method of weight ratio>
A powder is collected as a measurement sample from the positive electrode active material-containing layer on the measurement sample obtained by the above method using a spatula or the like. The resulting powder is washed with acetone and dried. The obtained powder is dissolved in hydrochloric acid, the conductive agent is filtered off, diluted with ion-exchanged water, and the metal content ratio is calculated by inductively coupled plasma emission spectroscopy. At the same time, the presence of lithium manganese composite oxide and lithium cobalt oxide is confirmed by X-ray diffraction and SEM-EDX. The chemical formulas and formula amounts of the lithium manganese composite oxide and lithium cobalt oxide were calculated from the obtained metal ratio, and the weight ratio of the lithium manganese composite oxide and lithium cobalt oxide contained in the sampled positive weight active material-containing layer was calculated. Ask. Let the obtained values be G and H.

<X-ray photoelectron spectroscopy measurement of positive electrode active material-containing layer>
Next, the procedure of X-ray photoelectron spectroscopy measurement of the positive electrode active material-containing layer will be described.

A measurement sample is obtained by the above-mentioned method for taking out the positive electrode. The obtained measurement sample is charged into an X-ray photoelectron spectrometer while being enclosed in an argon atmosphere. As the spectroscope, for example, an XPS measuring device (VG Theta Probe manufactured by Thermo Fisher Scientific Co., Ltd.) or a device having an equivalent function can be used.

As the excitation X-ray source, single crystal spectroscopic AlKα rays (light obtained by splitting AlKα rays with a single crystal in order to improve monochromaticity) are used. The excited X-ray source is irradiated so that the X-ray spot has an elliptical shape of 800 × 400 μm to obtain an X-ray photoelectron spectrum.

In XPS measurement, a region from the actual surface of the sample to a depth of, for example, 0 to 10 nm can be measured. Therefore, according to the XPS measurement, it is possible to obtain information from the surface of the positive electrode active material-containing layer to a depth of 0 to 10 nm. In other words, it can be said that the X-ray photoelectron spectroscopic spectrum for the positive electrode active material-containing layer is a spectrum for the surface of the positive electrode active material-containing layer.

From the obtained X-ray photoelectron spectrum, the maximum peak height A of the peak attributed to the 2p orbital of Al appearing in the binding energy region of 70 eV or more and less than 75 eV, and 2p of Al appearing in the binding energy region of 75 eV or more and 78 eV or less. The maximum peak height B of the peak attributed to the orbital is determined, and the average peak intensity C is calculated from the peak in the binding energy region of 65 eV or more and less than 70 eV.

Further, from the obtained X-ray photoelectron spectrum, the maximum peak height D of the peak attributed to the 2p _3/2 orbital of Ti appearing in the binding energy region of 638 eV or more and less than 645 eV was determined, and the bond of 635 eV or more and less than 638 eV was determined. The average peak intensity E is calculated from the peak in the energy region.

<Manufacturing method of positive electrode>
In the production of a positive electrode, for example, a positive electrode active material, a positive electrode conductive agent, and a binder are suspended in an appropriate solvent, and the obtained slurry is applied to a positive electrode current collector and dried to obtain a positive electrode active material-containing layer. After making, press. In addition, the positive electrode active material, the positive electrode conductive agent, and the binder may be formed in the form of pellets and used as the positive electrode active material-containing layer.

The effect of the surface of the positive electrode, that is, the surface of the positive electrode active material-containing layer in which a plurality of peaks of the binding energy of Al in the X-ray photoelectron spectroscopic spectrum are in the range of 70 eV or more and 78 eV or less is contained in the positive electrode active material by, for example, aging. It can also be realized by a coating formed on the surface of the layer. Hereinafter, a method for preparing the composition of the coating film formed on the surface of the positive electrode active material-containing layer will be described.

Using the positive electrode produced as described above, for example, a non-aqueous electrolyte battery containing a negative electrode and a non-aqueous electrolyte is produced. In order to form a predetermined film on the surface of the positive electrode, it is desirable that at least one of the non-aqueous electrolyte, the positive electrode active material, and the positive electrode current collector contains Al. The non-aqueous electrolyte preferably contains lithium aluminum tetrafluoride. The concentration of lithium aluminum tetrafluoride is preferably 0.001 mol / L or more and 0.1 mol / L or less, and more preferably 0.002 mol / L or more and 0.03 mol / L or less. Further, the positive electrode active material preferably contains a lithium manganese composite oxide having a composition formula of LiMn _2-x M _x O ₄ . The positive electrode current collector is preferably formed of an aluminum foil or an aluminum alloy foil.

After the first charge, for example, the produced non-aqueous electrolyte battery is aged at a high temperature (for example, 70 ° C.) for a long time (for example, 24 hours) in a charged state. As an example of these adjustments, the aging conditions shown in the examples can be mentioned. By doing so, the composition of the coating film formed on the surface of the positive electrode active material-containing layer can be prepared.

According to the first embodiment described above, a positive electrode is provided. The positive electrode includes a positive electrode active material-containing layer containing a lithium manganese composite oxide and lithium cobalt oxide. The positive electrode active material-containing layer has a surface in which a plurality of peaks of the binding energy of Al in the X-ray photoelectron spectroscopic spectrum are in the range of 70 eV or more and 78 eV or less. The positive electrode active material-containing layer satisfies the relational expression of 0 <H / (G + H) ≦ 0.1.

Since it has such a configuration, the positive electrode according to the first embodiment can suppress gas generation and suppress an increase in resistance.

(Second embodiment)

The non-aqueous electrolyte battery according to the second embodiment includes a positive electrode, a negative electrode, a non-aqueous electrolyte, and an exterior member.

As the positive electrode, for example, the positive electrode of the first embodiment is used. The positive electrode current collector may include a portion that does not support a positive electrode active material-containing layer on the surface. This portion can serve as a positive electrode tab. Alternatively, the positive electrode may include a positive electrode tab separate from the positive electrode current collector.

The negative electrode includes a negative electrode active material-containing layer. The negative electrode may further include a negative electrode current collector. The negative electrode active material-containing layer can be supported on at least one surface of the negative electrode current collector. That is, the negative electrode current collector can support the negative electrode active material-containing layer on one side or both sides. Further, the negative electrode current collector can include a portion that does not support the negative electrode active material-containing layer on the surface. This portion can serve as a negative electrode tab. Alternatively, the negative electrode may include a negative electrode tab separate from the negative electrode current collector.

The positive electrode and the negative electrode can form an electrode group. In the electrode group, the positive electrode active material-containing layer and the negative electrode active material-containing layer can face each other, for example, via a separator.

The electrode group can have various structures. For example, the electrode group can have a stack type structure. The electrode group having a stack type structure can be obtained, for example, by alternately stacking a plurality of positive electrodes and a plurality of negative electrodes with a separator sandwiched between the positive electrode active material-containing layer and the negative electrode active material-containing layer. Alternatively, the electrode group can have a winding structure. In the winding type electrode group, for example, one separator, one negative electrode, another separator, and one positive electrode are laminated in this order to form a laminated body, and this laminated body is formed. It can be obtained by turning.

The non-aqueous electrolyte battery according to the second embodiment may further include a positive electrode terminal and a negative electrode terminal. A part of the positive electrode terminal is electrically connected to a part of the positive electrode, so that the positive electrode terminal can serve as a conductor for electrons to move between the positive electrode and the external terminal. The positive electrode terminal can be connected to, for example, a positive electrode current collector, particularly a positive electrode tab. Similarly, the negative electrode terminal can serve as a conductor for electrons to move between the negative electrode and the external terminal by electrically connecting a part thereof to a part of the negative electrode. The negative electrode terminal can be connected to, for example, a negative electrode current collector, particularly a negative electrode tab.

The exterior member houses a group of electrodes and a non-aqueous electrolyte. The non-aqueous electrolyte can be impregnated into the electrode group in the exterior member. A part of each of the positive electrode terminal and the negative electrode terminal can also be extended from the exterior member.

Hereinafter, the positive electrode, the negative electrode, the non-aqueous electrolyte, the separator and the exterior member will be described in more detail.

<Positive electrode>

As the positive electrode, for example, the positive electrode of the first embodiment is used.

<Negative electrode>
The negative electrode has a negative electrode current collector and a negative electrode active material-containing layer supported on one or both sides of the negative electrode current collector and containing a negative electrode active material, a negative electrode conductive agent, and a binder.

The negative electrode active material contains a titanium-containing oxide. The type of the negative electrode active material can be one type or two or more types.

Examples of titanium-containing oxides include lithium titanium composite oxides, anatase-type titanium-containing oxides, rutile-type titanium-containing oxides, bronze-type titanium-containing oxides, orthocrystalline titanium-containing oxides, and monoclinic. Included are crystalline niobium titanium-containing oxides and metal composite oxides containing Ti and at least one element selected from the group consisting of P, V, Sn, Cu, Ni, Nb and Fe.

The lithium titanium composite oxide includes a lithium titanium oxide and a lithium titanium composite oxide in which some of the constituent elements of the lithium titanium oxide are replaced with different elements. Lithium-titanium oxide includes, for example, lithium titanate having a spinel-type structure (for example, Li _{4 + x} Ti ₅ O ₁₂ (x is a value that changes with charge / discharge, 0 ≦ x ≦ 3)), and rams delight-type titanium acid. Lithium (for example, Li _{2 + y} Ti ₃ O ₇ (y is a value that changes with charge / discharge, 0 ≦ y ≦ 3)) and the like can be mentioned. On the other hand, the molar ratio of oxygen is formally shown as 12 for spinel type Li _{4 + x} Ti ₅ O ₁₂ and 7 for rams delite type Li _{2 + y} Ti ₃ O ₇ , but these are due to the influence of oxygen non-stoicometry and the like. The value of can change.

Examples of the metal composite oxide containing Ti and at least one element selected from the group consisting of P, V, Sn, Cu, Ni, Nb and Fe include TiO ₂ -P ₂ O ₅ and TiO. ₂ -V ₂ O ₅ , TiO ₂ -P ₂ O ₅ -SnO ₂ , TiO ₂ -P ₂ O ₅ -MeO (Me is at least one element selected from the group consisting of Cu, Ni and Fe. ) And so on. This metal composite oxide has low crystallinity, and preferably has a microstructure in which a crystalline phase and an amorphous phase coexist or the amorphous phase alone exists. With such a microstructure, the cycle performance can be significantly improved.

The composition of anatase-type, rutile-type, and bronze-type titanium-containing oxides can be represented by TiO ₂ .

The orbital titanium-containing oxide is represented by the general formula Li _{2 + w} Na _2-x M1 _y Ti _6-z M2 _z O _{14 + δ} , M1 is Cs and / or K, and M2 is Zr, Sn, V. , Nb, Ta, Mo, W, Fe, Co, Mn, and a compound containing at least one of Al, 0 ≦ w ≦ 4, 0 ≦ x ≦ 2, 0 ≦ y ≦ 2, 0 ≦ z. <6, −0.5 ≦ δ ≦ 0.5.

The monoclinic niobium-titanium-containing oxide is represented by the general formula Li _x Ti _1-y M3 _y Nb _2-z M4 _z O _{7 + δ} , and M3 is composed of Zr, Si, Sn, Fe, Co, Mn and Ni. Examples include at least one compound selected from the group, M4 being at least one compound selected from the group consisting of V, Nb, Ta, Mo, W and Bi, 0 ≦ x ≦ 5, 0 ≦ y. <1, 0 ≦ z ≦ 2, −0.3 ≦ δ ≦ 0.3.

A preferred negative electrode active material is one containing a lithium titanium composite oxide.

Since the negative electrode containing a titanium-containing oxide such as a lithium-titanium composite oxide has an occlusion potential of 0.4 V (vs. Li / Li ⁺ ) or more, the negative electrode surface when input / output at a large current is repeated. It is possible to prevent the precipitation of metallic lithium on the above. The negative electrode active material may contain an active material other than the lithium-titanium composite oxide, but in that case, an active material having a Li occlusion potential of 0.4 V (vs. Li / Li ⁺ ) or more should be used. Is desirable.

Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine-based rubber, styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyimide, polyamide and the like. The type of binder may be one type or two or more types.

Examples of the negative electrode conductive agent include carbon black such as acetylene black and ketjen black, graphite, carbon fiber, carbon nanotube, and fullerene. The type of the conductive agent can be one type or two or more types.

The blending ratio of the negative electrode active material, the conductive agent and the binder in the negative electrode active material-containing layer is 70% by weight or more and 96% by weight or less of the negative electrode active material, 2% by weight or more and 28% by weight or less of the conductive agent, and 2% by weight of the binder. It is preferably 28% by weight or less. By blending the conductive agent in a ratio of 2% by weight or more, excellent high current characteristics due to high current collecting performance can be obtained. Further, by setting the amount of the binder to 2% by weight or more, the binding property between the negative electrode active material-containing layer and the negative electrode current collector can be improved and the cycle characteristics can be improved. On the other hand, from the viewpoint of increasing the capacity, the negative electrode conductive agent and the binder are preferably 28% by weight or less, respectively.

The current collector is preferably an aluminum foil or an aluminum alloy foil that is electrochemically stable in a potential range noble than 1.0 V.

For the negative electrode, for example, a negative electrode active material, a negative electrode conductive agent, and a binder are suspended in an appropriate solvent, the obtained slurry is applied to a negative electrode current collector, and dried to prepare a negative electrode active material-containing layer. It is produced by applying a press. In addition, the negative electrode active material, the negative electrode conductive agent, and the binder may be formed in the form of pellets and used as the negative electrode active material-containing layer.

The negative electrode active material-containing layer preferably has a porosity of 20% or more and 50% or less. The negative electrode active material-containing layer having such a porosity has an excellent affinity with a non-aqueous electrolyte and can be made denser. A more preferable porosity is 25% or more and 40% or less.

The density of the negative electrode active material-containing layer is preferably 2.0 g / cm ³ or more.

<Non-water electrolyte>
Examples of the non-aqueous electrolyte include a liquid non-aqueous electrolyte prepared by dissolving the electrolyte in a non-aqueous solvent, a gel-like non-aqueous electrolyte in which a liquid non-aqueous electrolyte and a polymer material are combined, and the like.

The electrolytes are, for example, lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium arsenic hexafluoride (LiAsF ₆ ), lithium difluorophosphate. Lithium salts such as (LiPO ₂ F ₂ ), lithium trifluoromethsulfonate (LiCF ₃ SO ₃ ), bistrifluoromethylsulfonylimide lithium [LiN (CF ₃ SO ₂ ) ₂ ], lithium tetrafluorofluorofluorocarbon (LiAlF ₄ ). Can be mentioned. These electrolytes may be used alone or in admixture of two or more. The electrolyte preferably contains lithium hexafluorophosphate or lithium aluminum tetrafluoride, and more preferably lithium hexafluorophosphate and lithium aluminum tetrafluoride.

The electrolyte is preferably dissolved in a non-aqueous solvent in the range of 0.5 mol / L or more and 2.5 mol / L or less.

The non-aqueous solvent is, for example, a cyclic carbonate such as ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC); a chain such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC). Cyclic ethers such as tetrahydrofuran (THF), 2-methyltetrahydrofuran (2MeTHF); chain ethers such as dimethoxyethane (DME); cyclic esters such as γ-butyrolactone (BL); methyl acetate, ethyl acetate, methyl propionate. , Chain esters such as ethyl propionate; organic solvents such as acetonitrile (AN); sulfolane (SL). These organic solvents can be used alone or in the form of a mixture of two or more.

Examples of the polymer material used for the gel-like non-aqueous electrolyte include polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyethylene oxide (PEO) and the like.

<Separator>
Examples of the separator include a porous film containing polyethylene, polypropylene, cellulose, polyvinylidene fluoride (PVdF), a non-woven fabric made of synthetic resin, and the like.

<Exterior member>
The exterior member may be formed of a laminated film or may be made of a metal container. When using a metal container, the lid can be integrated with or separate from the container. The wall thickness of the metal container is more preferably 0.5 mm or less and 0.2 mm or less. Examples of the shape of the exterior member include a flat type, a square type, a cylindrical type, a coin type, a button type, a sheet type, and a laminated type. In addition to a small battery loaded on a portable electronic device or the like, a large battery loaded on a two-wheeled or four-wheeled vehicle may be used.

It is desirable that the wall thickness of the exterior member made of laminated film is 0.2 mm or less. Examples of the laminated film include a multilayer film including a resin film and a metal layer arranged between the resin films. The metal layer is preferably an aluminum foil or an aluminum alloy foil in order to reduce the weight. As the resin film, for example, a polymer material such as polypropylene (PP), polyethylene (PE), nylon, or polyethylene terephthalate (PET) can be used. The laminated film can be sealed by heat fusion and molded into the shape of an exterior member.

Metal containers are made of aluminum or aluminum alloys and the like. As the aluminum alloy, an alloy containing elements such as magnesium, zinc, and silicon is preferable. In aluminum or an aluminum alloy, it is preferable that the content of transition metals such as iron, copper, nickel and chromium is 100 ppm or less in order to dramatically improve long-term reliability and heat dissipation in a high temperature environment.

It is desirable that the metal container made of aluminum or an aluminum alloy has an average crystal grain size of 50 μm or less, more preferably 30 μm or less, still more preferably 5 μm or less. By setting the average crystal grain size to 50 μm or less, the strength of the metal container made of aluminum or an aluminum alloy can be dramatically increased, and the container can be further thinned. As a result, it is possible to realize a non-aqueous electrolyte battery suitable for in-vehicle use, which is lightweight, has high output, and has excellent long-term reliability.

Next, a specific example of the non-aqueous electrolyte battery according to the embodiment will be described with reference to the drawings.

First, the non-aqueous electrolyte battery of the first example according to the embodiment will be described with reference to FIGS. 1 and 2.

FIG. 1 is a partially cutaway perspective view of an example of a non-aqueous electrolyte battery according to a second embodiment. FIG. 2 is an enlarged cross-sectional view of part A of the non-aqueous electrolyte battery shown in FIG.

The non-aqueous electrolyte battery 100 shown in FIGS. 1 and 2 includes a flat electrode group 1 and an exterior member 7 made of a laminated film. The flat electrode group 1 includes a negative electrode 2, a positive electrode 3, and a separator 4. In the flat electrode group 1, the negative electrode 2 and the positive electrode 3 are wound in a flat shape with a separator 4 interposed therebetween.

As shown in FIG. 2, the negative electrode 2 includes a negative electrode current collector 21 and a negative electrode active material-containing layer 22 supported on the negative electrode current collector 21. As shown in FIG. 2, in the outermost portion of the negative electrode 2, the negative electrode active material-containing layer 22 is placed on the main surface of the two main surfaces of the negative electrode current collector 21 that does not face the positive electrode 3. Not carried. In the other portion of the negative electrode 2, the negative electrode active material-containing layer 22 is supported on both main surfaces of the negative electrode current collector. As shown in FIG. 2, the positive electrode 3 includes a positive electrode current collector 31 and a positive electrode active material-containing layer 32 supported on two main surfaces of the positive electrode current collector 31.

A band-shaped negative electrode terminal 5 is electrically connected to the negative electrode 2. A band-shaped positive electrode terminal 6 is electrically connected to the positive electrode 3.

The electrode group 1 is housed in the exterior member 7 made of a laminated film in a state where the ends of the negative electrode terminal 5 and the positive electrode terminal 6 are extended from the exterior member 7. A non-aqueous electrolyte (not shown) is housed in the laminated film exterior member 7. The non-aqueous electrolyte is impregnated in the electrode group 1. The exterior member 7 made of a laminated film is sealed by heat-sealing each of the end portion and the two end portions 71 orthogonal to the end portion in a state where the negative electrode terminal 5 and the positive electrode terminal 6 are sandwiched between one end portions. Has been done.

Next, the non-aqueous electrolyte battery of the second example according to the embodiment will be described with reference to FIG.

FIG. 3 is an exploded perspective view of another example of the non-aqueous electrolyte battery according to the second embodiment.

The non-aqueous electrolyte battery 100 shown in FIG. 3 includes a container body 7, a lid 8, and an electrode group 1.

The container body 7 is made of metal and has a bottomed square tube shape having an opening. A lid 8 is arranged at the opening of the container body 7 and is closed by the lid 8. The container body 7 houses the electrode group 1 and a non-aqueous electrolyte (not shown). The container body 7 and the lid 8 form an exterior member.

The lid 8 includes a sealing plate 81. It is desirable that the sealing plate 81 is made of the same type of metal as the container body 7. The peripheral edge of the sealing plate 81 is welded to the peripheral edge of the opening of the container body 7. The sealing plate 81 is provided with a safety valve 82 that can operate as a gas release structure.

The safety valve 82 includes a cross groove 83 provided on the bottom surface of a rectangular recess provided in the sealing plate 81. The portion of the sealing plate 81 provided with the groove 83 is particularly thin. Therefore, the groove 83 can release the gas in the container body 7 to the outside by breaking when the internal pressure of the container body 7 rises.

Further, the sealing plate 81 is provided with a liquid injection hole 81a in addition to the safety valve 82. A positive electrode terminal 84, a negative electrode terminal 85, two external insulating materials 86, two internal insulating materials (not shown), and two terminal leads 87 are fixed to the sealing plate 81.

The electrode group 1 includes a positive electrode (not shown), a negative electrode (not shown), and a separator (not shown). In the flat electrode group 1, the positive electrode and the negative electrode are wound in a flat shape with a separator interposed therebetween. The electrode group 1 is impregnated with a non-aqueous electrolyte (not shown).

The positive electrode includes a band-shaped positive electrode current collector and a positive electrode active material-containing layer formed on a part of the surface of the current collector. The positive electrode current collector includes a plurality of positive electrode current collector tabs 33 having no positive electrode active material-containing layer formed on the surface thereof. The plurality of positive electrode current collecting tabs 33 extend from the end faces facing the lid 8 of the electrode group 1. In addition, in FIG. 3, a plurality of positive electrode current collector tabs 33 are described as one member 33 which is an aggregate.

The negative electrode includes a band-shaped negative electrode current collector and a negative electrode active material-containing layer formed on a part of the surface of the current collector. The negative electrode current collector includes a plurality of negative electrode current collector tabs 23 having no negative electrode active material-containing layer formed on the surface thereof. The plurality of negative electrode current collecting tabs 23 extend from the end faces facing the lid 8 of the electrode group 1. In addition, in FIG. 3, a plurality of negative electrode current collector tabs 23 are described as one member 23 which is an aggregate.

The two terminal leads 87 are fixed to the sealing plate 81 together with the positive electrode terminal 84 and the negative electrode terminal 85, the two external insulating materials 86, and the two internal insulating materials.

The positive electrode terminal 84 and the negative electrode terminal 85 are each electrically insulated from the sealing plate 81. The two terminal leads 87 are also insulated from the sealing plate 81.

On the other hand, the positive electrode terminal 84 is electrically connected to one of the terminal leads 87 fixed to the sealing plate 81 together with the positive electrode terminal 84. Similarly, the negative electrode terminal 85 is electrically connected to the other terminal lead 87 fixed to the sealing plate 81 together with the negative electrode terminal 85.

In the non-aqueous electrolyte battery 100 shown in FIG. 3, the liquid injection hole 81a provided in the sealing plate 81 constitutes a liquid injection passage for injecting the non-water electrolyte into the inside of the non-water electrolyte battery 100 from the outside. There is. The liquid injection hole 81a is closed by a metal sealing lid 9. The peripheral edge of the sealing lid 9 is welded to the sealing plate 81.

In the non-aqueous electrolyte battery 100 shown in FIG. 3, the terminal lead 87 electrically connected to the positive electrode terminal 84 is electrically connected to the positive electrode current collecting tab 33. Further, the terminal lead 87 electrically connected to the negative electrode terminal 85 is electrically connected to the negative electrode current collector tab 23.

Since the non-aqueous electrolyte battery according to the second embodiment includes the positive electrode according to the first embodiment, it is possible to suppress the generation of gas in the battery and the increase in battery resistance.

(Third embodiment)
According to the third embodiment, a battery pack including a non-aqueous electrolyte battery is provided. As the non-aqueous electrolyte battery, the non-aqueous electrolyte battery according to the first embodiment is used. The number of non-aqueous electrolyte batteries (cells) included in the battery pack may be one or more.

A plurality of non-aqueous electrolyte batteries can be electrically connected in series, in parallel, or in series and in parallel to form an assembled battery. The battery pack may include a plurality of assembled batteries.

The battery pack may further include a protection circuit. The protection circuit has a function of controlling the charging / discharging of the non-aqueous electrolyte battery. Further, a circuit included in a device using a battery pack as a power source (for example, an electronic device, an automobile, etc.) can be used as a protection circuit of the battery pack.

The battery pack may also be further provided with an external terminal for energization. The external terminal for energization is for outputting the current from the non-aqueous electrolyte battery to the outside and for inputting the current to the non-aqueous electrolyte battery. In other words, when the battery pack is used as a power source, current is supplied to the outside through an external terminal for energization. Further, when charging the battery pack, the charging current (including the regenerative energy of the power of the automobile) is supplied to the battery pack through an external terminal for energization.

Next, an example of the battery pack according to the third embodiment will be described with reference to the drawings.

FIG. 4 is an exploded perspective view of an example of the battery pack according to the third embodiment. FIG. 5 is a block diagram showing an electric circuit of the battery pack shown in FIG.

The battery pack 200 shown in FIGS. 4 and 5 includes a plurality of flat batteries 100 having the structures shown in FIGS. 1 and 2.

The plurality of cell cells 100 are laminated so that the negative electrode external terminal 5 and the positive electrode external terminal 6 extending to the outside are aligned in the same direction, and are fastened with an adhesive tape 122, thereby forming the assembled battery 123. ing. These cell cells 100 are electrically connected in series with each other as shown in FIG.

The printed wiring board 124 is arranged so as to face the side surface on which the negative electrode external terminal 5 and the positive electrode external terminal 6 of the plurality of cells 100 extend. As shown in FIG. 5, the printed wiring board 124 is equipped with a thermistor 125, a protection circuit 126, and a terminal 127 for energizing an external device. An insulating plate (not shown) is attached to the surface of the printed wiring board 124 facing the assembled battery 123 in order to avoid unnecessary connection with the wiring of the assembled battery 123.

The positive electrode side lead 128 is connected to the positive electrode external terminal 6 of the cell 100 located at the bottom layer of the assembled battery 123, and the tip thereof is inserted into the positive electrode side connector 129 of the printed wiring board 124 and electrically connected. There is. The negative electrode side lead 130 is connected to the negative electrode external terminal 5 of the cell 100 located on the uppermost layer of the assembled battery 123, and the tip thereof is inserted into the negative electrode side connector 131 of the printed wiring board 124 and electrically connected. There is. These connectors 129 and 131 are connected to the protection circuit 126 through the wirings 132 and 133 formed on the printed wiring board 124, respectively.

The thermistor 125 detects the temperature of each of the cell 100 and transmits the detection signal to the protection circuit 126. The protection circuit 126 can cut off the positive side wiring 134a and the negative side wiring 134b between the protection circuit 126 and the terminal 127 for energizing the external device under predetermined conditions. An example of a predetermined condition is when a signal that the temperature of the cell 100 is equal to or higher than the predetermined temperature is received from, for example, the thermistor 125. Another example of the predetermined condition is when the cell 100 is detected to be overcharged, overdischarged, overcurrent, or the like. This detection of overcharging or the like is performed on the individual cell 100 or the entire cell 100. When detecting the individual cell 100, the battery voltage may be detected, or the positive electrode potential or the negative electrode potential may be detected. In the latter case, a lithium electrode used as a reference electrode is inserted into each cell 100. In the battery pack 200 of FIGS. 4 and 5, wiring 135 for voltage detection is connected to each of the cell 100, and the detection signal is transmitted to the protection circuit 126 through these wiring 135.

A protective sheet 136 made of rubber or resin is arranged on each of the three side surfaces of the assembled battery 123 excluding the side surface on which the positive electrode external terminal 6 and the negative electrode external terminal 5 project.

The assembled battery 123 is housed in a storage container 137 together with each protective sheet 136 and a printed wiring board 124. That is, the protective sheet 136 is arranged on both inner side surfaces in the long side direction and the inner side surface in the short side direction of the storage container 137, and the printed wiring board 124 is arranged on the inner side surface on the opposite side in the short side direction. There is. The assembled battery 123 is located in a space surrounded by the protective sheet 136 and the printed wiring board 124. The lid 138 is attached to the upper surface of the storage container 137.

A heat-shrinkable tape may be used instead of the adhesive tape 122 to fix the assembled battery 123. In this case, protective sheets are arranged on both side surfaces of the assembled battery, the heat-shrinkable tube is circulated, and then the heat-shrinkable tube is heat-shrinked to bind the assembled battery.

The battery pack 200 shown in FIGS. 4 and 5 has a form in which a plurality of cell cells 100 are connected in series, but the battery pack according to the third embodiment has a plurality of cell cells 100 in order to increase the battery capacity. May be connected in parallel. Alternatively, the battery pack according to the third embodiment may include a plurality of cell cells 100 connected by combining a series connection and a parallel connection. The assembled battery pack 200 can be further connected in series or in parallel.

Further, although the battery pack 200 shown in FIGS. 4 and 5 includes a plurality of cell cells 100, the battery pack according to the third embodiment may include one cell cell 100.

Further, the aspect of the battery pack 200 is appropriately changed depending on the intended use. The battery pack 200 is preferably used in which cycle characteristics with high current characteristics are desired. Specific examples thereof include a power source for a digital camera, a two-wheeled to four-wheeled hybrid electric vehicle, a two-wheeled to four-wheeled electric vehicle, and an in-vehicle use such as an assisted bicycle. In particular, it is suitable for in-vehicle use.

In the automobile equipped with the battery pack according to the present embodiment, the battery pack recovers, for example, the regenerative energy of the power of the automobile.

The battery pack of the third embodiment includes the non-aqueous electrolyte battery of the first embodiment. Therefore, the battery pack according to the third embodiment can suppress the generation of gas in the battery and the increase in battery resistance.

[Example]
The embodiments will be described in more detail with reference to the following examples, but the embodiments are not limited to the examples described below as long as the gist of the invention is not exceeded.

(Example 1)
In Example 1, the positive electrode and the non-aqueous electrolyte battery of Example 1 were produced by the following procedure.

<Creation of positive electrode>
As the positive electrode active material, particles of spinel-type lithium manganese composite oxide (LMO) represented by the composition formula LiMn _1.9 Al _0.1 O ₄ and lithium cobalt oxide (LCO) represented by the composition formula LiCoO ₂ Prepared with particles. The LMO particles contained secondary particles, and the average secondary particle diameter was 10 μm. The average particle size of the primary particles of LCO was 8 μm. In addition, acetylene black and graphite as conductive agents and polyvinylidene fluoride (PVdF) as a binder were prepared. These were added to N-methylpyrrolidone (NMP) and mixed so that the mixing ratio of LMO particles: LCO particles: acetylene black: graphite: PVdF was 90:10: 4: 1: 4 by weight. .. Thus, a positive electrode slurry was prepared. This positive electrode slurry was applied to both sides of a current collector made of aluminum foil having a thickness of 15 μm, dried, and then pressed to prepare a positive electrode having a positive electrode active material-containing layer having a basis weight of 80 g / m ² on each side.

<Creation of negative electrode>
As the negative electrode active material, particles of spinel-type lithium titanate (LTO) represented by the composition formula Li ₄ Ti ₅ O ₁₂ were prepared. Further, graphite as a conductive agent and PVdF as a binder were prepared. These were added to NMP and mixed so that the mixing ratio of LTO particles: graphite: PVdF was 100: 9: 4 by weight. Thus, a negative electrode slurry was prepared. This negative electrode slurry was applied to both sides of a current collector made of aluminum foil having a thickness of 15 μm, dried, and then pressed to prepare a negative electrode having a negative electrode active material-containing layer having a basis weight of 40 g / m ² on one side.

<Preparation of electrode group>
A positive electrode prepared as described above, a resin separator having a thickness of 15 μm, a negative electrode prepared as described above, and another separator were laminated in this order to obtain a laminated body. This laminated body was spirally wound so that the negative electrode was located on the outermost circumference to prepare an electrode group. After removing the winding core, the wound laminate was subjected to a heating press at 90 ° C. Thus, a group of flat electrodes having a width of 50 mm, a height of 95 mm, and a thickness of 10 mm was produced.

<Preparation of non-aqueous electrolyte solution>
Ethylmethyl carbonate (EMC) and ethylene carbonate (EC) were mixed in a volume ratio of 1: 1 to prepare a mixed solvent. A non-aqueous electrolytic solution was prepared by dissolving 1.0 mol / L lithium hexafluorophosphate (LiPF ₆ ) and 0.01 mol / L lithium aluminum tetrafluoride (LiAlF ₄ ) in this mixed solvent.

<Making batteries>
The flat electrode group prepared as described above was inserted into a bottomed rectangular tubular can (outer container) made of aluminum having a thickness of 0.3 mm.

The electrode group in the outer container to which the sealing plate was attached was put into a dryer and vacuum dried at 95 ° C. for 6 hours. After drying, it was carried to a glove box controlled to have a dew point of -50 ° C or lower. 70 ml of the previously prepared non-aqueous electrolytic solution was injected from the injection port of the sealing plate. After injecting the non-aqueous electrolytic solution, the injection port was sealed with a sealing lid under a reduced pressure environment of −90 kPa.

<Aging>
The sealed product was adjusted to 100% SOC by charging at a 1 C rate under a 25 ° C environment. Next, it was left in a constant temperature bath at 70 ° C. for 24 hours for aging. After aging, the outer container was opened and resealed under a reduced pressure environment of −90 kPa.

Thus, the non-aqueous electrolyte battery of Example 1 was produced.

(Example 2)
In Example 2, as shown in Table 1, the non-aqueous electrolyte of Example 2 was prepared in the same manner as in Example 1 except that LiAlF ₄ was dissolved at a concentration of 0.03 mol / L to prepare a non-aqueous electrolyte. A battery was made.

(Example 3)
In Example 3, as shown in Table 1, the non-aqueous electrolyte of Example 3 was prepared in the same manner as in Example 1 except that LiAlF ₄ was dissolved at a concentration of 0.002 mol / L to prepare a non-aqueous electrolyte. A battery was made.

(Example 4)
In Example 4, as shown in Table 1, the non-existence of Example 4 is the same as in Example 1 except that the particles of LMO represented by the composition formula LiMn _1.8 Al _0.2 O ₄ are used. A water electrolyte battery was manufactured.

(Example 5)
In Example 5, as shown in Table 1, LMO particles represented by the composition formula LiMn _1.8 Al _0.2 O ₄ were used, and LiAlF ₄ was dissolved at a concentration of 0.002 mol / L. The non-aqueous electrolyte battery of Example 5 was produced in the same manner as in Example 1 except that the non-aqueous electrolyte was prepared.

(Example 6)
In Example 6, as shown in Table 1, the non-existence of Example 6 is the same as in Example 1 except that the particles of LMO represented by the composition formula LiMn _1.6 Al _0.4 O ₄ are used. A water electrolyte battery was manufactured.

(Example 7)
In Example 7, as shown in Table 1, the particles of LMO represented by the composition formula LiMn _1.6 Al _0.4 O ₄ were used, and Example 1 was not added except that LiAlF ₄ was not added. In the same manner as in the above, the non-aqueous electrolyte battery of Example 7 was produced.

(Example 8)
In Example 8, as shown in Table 1, the non-aqueous electrolyte battery of Example 8 was produced in the same manner as in Example 1 except that LiAlF ₄ was not added.

(Example 9)
In Example 9, as shown in Table 1, the non-aqueous electrolyte of Example 9 was prepared in the same manner as in Example 1 except that LiAlF ₄ was dissolved at a concentration of 0.1 mol / L to prepare a non-aqueous electrolyte. A battery was made.

(Example 10)
In Example 10, the liquid was injected and sealed under reduced pressure in the same manner as in Example 1, and then the sealed product was adjusted to 2.4 V by charging at a 1 C rate under a 25 ° C. environment. Next, it was left in a constant temperature bath at 70 ° C. for 24 hours for aging. After aging, the outer container was opened and sealed again in a reduced pressure environment of −90 kPa to prepare a non-aqueous electrolyte battery of Example 10.

(Example 11)
In Example 11, as shown in Table 1, the particles of LMO represented by the composition formula LiMn _1.6 Al _0.4 O ₄ were used, and LiAl F ₄ was not added, except that Example 1 was used. After injecting liquid and sealing under reduced pressure in the same manner as above, the sealed product was adjusted to 2.4 V by charging at a rate of 1 C under a 25 ° C. environment. Next, it was left in a constant temperature bath at 70 ° C. for 24 hours for aging. After aging, the outer container was opened and sealed again in a reduced pressure environment of −90 kPa to prepare a non-aqueous electrolyte battery of Example 11.

(Comparative Example 1)
In Comparative Example 1, as shown in Table 1, the particles of LMO represented by the composition formula LiMn _1.9 Al _0.1 O ₄ were used, and the same as in Example 1 except that the particles of LCO were not added. Then, the non-aqueous electrolyte battery of Comparative Example 1 was produced.

(X-ray photoelectron spectroscopy measurement of the surface of the positive electrode)
6 and 7 show the results of subjecting the surface of the positive electrode active material-containing layer included in the non-aqueous electrolyte battery of Example 7 to X-ray photoelectron spectroscopy according to the method described above. The spectra shown in FIGS. 6 and 7 are actually measured XPS spectra. The horizontal axis is the binding energy eV. The vertical axis of FIG. 6 is count / sec (residual × 2) (Counts / s (Resid × 2), and the magnification of the vertical axis of the residual is 2 times. The vertical axis of FIG. 7 is count / sec (residual). Residual x 5) (Counts / s (Resid x 5)), and the magnification of the vertical axis of the residual is 5 times. From the spectrum shown in FIG. 6, the region of the coupling energy within the range of 70 eV or more and 78 eV or less. It can be seen that two peaks P1 and P2 attributed to electrons in the 2p orbit of Al are included in.

Further, in the spectrum shown in FIG. 6, the binding energy of Al of the peak P1 having the maximum peak height in the range of 70 eV or more and less than 75 eV is 73.6 eV, and the peak having the maximum peak height in the range of 75 eV or more and 78 eV or less. The binding energy of Al of P2 was 75.5 eV. From this, it can be seen that one peak P1 and one P2 attributed to the electron in the 2p orbital of Al are included in the region of the binding energy in the range of 70 eV or more and less than 75 eV and in the range of 75 eV or more and 78 eV or less.

Further, in the spectrum shown in FIG. 7, the binding energy of Mn of the peak P3 having the maximum peak height in the range of 638 eV or more and 645 eV or less was 642.5 eV. From this, it can be seen that one peak P3 attributed to an electron in the 2p _3/2 orbital of Mn is included in the region of the binding energy in the range of 638 eV or more and 645 eV or less.

Although not shown, it was confirmed by the above-mentioned X-ray photoelectron spectroscopy that the positive electrode active material-containing layer contained each element of Li, C, O, F, P, Ti, and Co.

Also in Examples 1 to 6, 8 to 11 and Comparative Example 1, two peaks attributed to electrons in the 2p orbital of Al appear in the region of binding energy of 70 eV or more and 78 eV or less, and within the range of 70 eV or more and less than 75 eV. And one peak attributed to an electron in the 2p orbital of Al is included in the binding energy region within the range of 75 eV or more and 78 eV or less, and Mn is included in the binding energy region within the range of 638 eV or more and 645 eV or less. The fact that one peak attributed to an electron in the 2p _3/2 orbital is contained, and that the positive electrode active material-containing layer contains each element of Li, C, O, F, P, Ti, and Co. confirmed.

In addition, the results of calculating (BC) / (AC) and (BC) / (DE) from the results of the above X-ray photoelectron spectroscopy measurement by the procedure described above are shown in the table. Shown in 2.

(0.2 second discharge resistance)
After adjusting the voltage of the non-aqueous electrolyte batteries of Examples 1 to 11 and Comparative Example 1 to a voltage of SOC 50%, the voltage when the currents of 1C and 10C were continuously applied for 0.2 seconds in an environment of 25 ° C. Table 2 shows the 0.2 second resistance calculated by the following equation when V1 and V2 are used.
0.2 second resistance (Ω) = (V1-V2) / (10-1)

(Cell thickness after storage and discharge resistance for 0.2 seconds)
The non-aqueous electrolyte batteries of Examples 1 to 11 and Comparative Example 1 were adjusted to 100% SOC and stored at 75 ° C. for 1 week. Table 2 shows the results of measuring the cell thickness in an environment of 25 ° C. after storage and calculating the difference (mm) from the cell thickness before storage.

Table 2 shows the results of measuring the 0.2-second discharge resistance of each of the non-aqueous electrolyte batteries of Examples 1 to 11 and Comparative Example 1 in an environment of 25 ° C. after storage.

As shown in Table 2, the non-aqueous electrolyte batteries of Examples 1 to 11 had a smaller cell thickness after storage than the non-aqueous electrolyte batteries of Comparative Example 1. Further, the non-aqueous electrolyte batteries of Examples 1 to 11 showed 0.2 second resistance and 0.2 second resistance after storage, which were similar to those of Comparative Example 1.

From these results, it can be seen that the non-aqueous electrolyte batteries of Examples 1 to 11 have suppressed gas generation as compared with the non-aqueous electrolyte batteries of Comparative Example 1. It is considered that this is because the non-aqueous electrolyte battery of Comparative Example 1 could not absorb the generated gas because LiCoO ₂ was not contained in the positive electrode active material.

In addition, the non-aqueous electrolyte batteries of Examples 1 to 7 had small cell thickness after storage, 0.2 second discharge resistance, and 0.2 second resistance after storage. This is because (BC) / (AC) is in the range of 0.3 or more and 2 or less, and (BC) / (DE) is 0.004 or more and 0.04 or less. It is considered that when the content is within the range of 1), the conductivity of Li ions on the positive electrode is not significantly reduced by the film formed on the positive electrode active material-containing layer, and the gas generation is suppressed.

That is, the positive electrode according to at least one embodiment and the above-described embodiment includes a positive electrode active material-containing layer containing a positive electrode active material containing a lithium manganese composite oxide and lithium cobalt oxide, and is a positive electrode active material-containing layer. Has a surface in which a plurality of peaks of the bonding energy of Al in the X-ray photoelectron spectroscopic spectrum are in the range of 70 eV or more and 78 eV or less, and satisfies the relational expression of 0 <H / (G + H) ≦ 0.1. G is the weight ratio of the lithium manganese composite oxide in the positive electrode active material. H is the weight ratio of lithium cobalt oxide in the positive electrode active material. The non-aqueous electrolyte battery provided with this positive electrode can suppress gas generation while suppressing an increase in resistance value. As a result, this non-aqueous electrolyte battery can exhibit excellent input / output characteristics, excellent life characteristics, and improved safety.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and variations thereof are included in the scope of the invention described in the claims and the equivalent scope thereof, as are included in the scope and gist of the invention.
The inventions described in the original claims of the present application are described below.
[1]
It contains a positive electrode active material-containing layer containing a positive electrode active material containing a lithium manganese composite oxide and lithium cobalt oxide.
The positive electrode active material-containing layer has a surface in which a plurality of peaks of the binding energy of Al in the X-ray photoelectron spectroscopic spectrum are in the range of 70 eV or more and 78 eV or less.
Positive electrode satisfying the following formula (1):
0 <H / (G + H) ≤ 0.1 (1)
Here, G is the weight ratio of the lithium manganese composite oxide in the positive electrode active material, and H is the weight ratio of the lithium cobalt oxide in the positive electrode active material.
[2]
The surface of the positive electrode active material-containing layer is such that at least one of the plurality of peaks of the binding energy of Al in the X-ray photoelectron spectroscopy is present in the range of 70 eV or more and less than 75 eV and in the range of 75 eV or more and 78 eV or less. The positive electrode according to [1].
[3]
The positive electrode according to [1] or [2] that satisfies the following formula (2):
0.3 ≤ (BC) / (AC) ≤ 2 (2)
Here, A is the maximum peak height of the X-ray photoelectron spectroscopic spectrum in the range of 70 eV or more and less than 75 eV of the binding energy of Al.
B is the maximum peak height of the X-ray photoelectron spectroscopic spectrum in the range of 75 eV or more and 78 eV or less of the binding energy of Al.
C is the average peak height of the X-ray photoelectron spectroscopy spectrum in the range of 65 eV or more and less than 70 eV of the binding energy of Al.
[4]
The positive electrode according to any one of [1] to [3] that satisfies the following formula (3):
0.004 ≤ (BC) / (DE) ≤ 0.04 (3)
Here, D is the maximum peak height of the X-ray photoelectron spectroscopic spectrum in the range of 638 eV or more and 645 eV or less of the binding energy of Mn.
E is the average peak height of the X-ray photoelectron spectroscopy spectrum in the range of 635 eV or more and less than 638 eV of the binding energy of Mn.
[5]
The composition formula of the lithium manganese composite oxide is LiMn _2-x M _x O ₄ , where the subscript x is in the range of 0.1 ≦ x ≦ 0.7, and M is Mg, Ti, Cr. The positive electrode according to any one of [1] to [4], which is at least one metal element selected from the group consisting of Fe, Co, Zn, Al and Ga.
[6]
A non-aqueous electrolyte battery comprising the positive electrode, the negative electrode, and the non-aqueous electrolyte according to any one of [1] to [5].
[7]
A battery pack including the non-aqueous electrolyte battery according to [6].

Claims (6)

It contains a positive electrode active material-containing layer containing a positive electrode active material containing a lithium manganese composite oxide and lithium cobalt oxide.
The positive electrode active material-containing layer has a surface in which a plurality of peaks of the binding energy of Al in the X-ray photoelectron spectroscopic spectrum are in the range of 70 eV or more and 78 eV or less.
Positive electrode satisfying the following formula (1) and the following formula (2) :
0 <H / (G + H) ≤ 0.1 (1)
Here, G is the weight ratio of the lithium manganese composite oxide in the positive electrode active material, and H is the weight ratio of the lithium cobalt oxide in the positive electrode active material.
0.3 ≤ (BC) / (AC) ≤ 2 (2)
Here, A is the maximum peak height of the X-ray photoelectron spectroscopic spectrum in the range of 70 eV or more and less than 75 eV of the binding energy of Al.
B is the maximum peak height of the X-ray photoelectron spectroscopic spectrum in the range of 75 eV or more and 78 eV or less of the binding energy of Al.
C is the average peak height of the X-ray photoelectron spectroscopy spectrum in the range of 65 eV or more and less than 70 eV of the binding energy of Al. The surface of the positive electrode active material-containing layer is such that at least one of the plurality of peaks of the binding energy of Al in the X-ray photoelectron spectroscopy is present in the range of 70 eV or more and less than 75 eV and in the range of 75 eV or more and 78 eV or less. The positive electrode according to claim 1. The positive electrode according to claim 1 or 2 , which satisfies the following formula (3):
0.004 ≤ (BC) / (DE) ≤ 0.04 (3)
Here, D is the maximum peak height of the X-ray photoelectron spectroscopic spectrum in the range of 638 eV or more and 645 eV or less of the binding energy of Mn.
E is the average peak height of the X-ray photoelectron spectroscopy spectrum in the range of 635 eV or more and less than 638 eV of the binding energy of Mn. The composition formula of the lithium manganese composite oxide is LiMn _2-x M _x O ₄ , where the subscript x is in the range of 0.1 ≦ x ≦ 0.7, and M is Mg, Ti, Cr. The positive electrode according to any one of claims 1 to 3 , which is at least one metal element selected from the group consisting of Fe, Co, Zn, Al and Ga. A non-aqueous electrolyte battery comprising the positive electrode, the negative electrode, and the non-aqueous electrolyte according to any one of claims 1 to 4 . A battery pack comprising the non-aqueous electrolyte battery according to claim 5 .

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