WO2020008565A1

WO2020008565A1 - Positive electrode, non-aqueous electrolyte battery, and battery pack

Info

Publication number: WO2020008565A1
Application number: PCT/JP2018/025369
Authority: WO
Inventors: 尚己西尾; 泰章村司; 矢嶋　亨; 夏希中村
Original assignee: 株式会社東芝
Priority date: 2018-07-04
Filing date: 2018-07-04
Publication date: 2020-01-09
Also published as: JP7024083B2; JPWO2020008565A1

Abstract

According to an embodiment, provided is a positive electrode. The positive electrode includes a positive electrode active material-containing layer, the positive electrode active material including a lithium manganese composite oxide and a lithium cobalt oxide. The positive electrode active material-containing layer has a surface in which a plurality of peaks of Al binding energy in the X-ray photoelectron spectroscopy spectrum are in the range of 70-78 eV. The positive electrode active material-containing layer satisfies the relational formula of 0<H/(G+H)≤0.1. Here, G is the weight percentage of the lithium manganese composite oxide in the positive electrode active material. H is the weight percentage of the lithium cobalt oxide in the positive electrode active material.

Description

Positive electrode, non-aqueous electrolyte battery, and battery pack

The embodiment of the present invention relates to a positive electrode, a non-aqueous electrolyte battery, and a battery pack.

When the non-aqueous electrolyte battery is in a high charge state, self-discharge occurs on the surface of the electrode, and a decomposition reaction of the electrolyte occurs. 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 increases. There is a problem that such gas generation can be a factor that lowers the safety of the battery.

JP 2010-23001 A JP 2016-48671 A

The problem to be solved by the present invention is to provide a positive electrode in which gas generation is suppressed, and a nonaqueous electrolyte battery and a battery pack including the positive electrode.

According to an 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 having a plurality of Al binding energy peaks in the range of 70 eV to 78 eV in the X-ray photoelectron spectroscopy spectrum. The positive electrode active material-containing layer satisfies the relational expression of 0 <H / (G + H) ≦ 0.1. Here, G is a 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.
According to another embodiment, a non-aqueous electrolyte battery is provided. The non-aqueous electrolyte battery includes the positive electrode of the embodiment, a negative electrode, and a non-aqueous electrolyte.
According to another embodiment, a battery pack is provided. The battery pack includes the nonaqueous electrolyte battery of the embodiment.

FIG. 1 is a partially cutaway perspective view of an example of a nonaqueous electrolyte battery according to a second embodiment. FIG. 2 is an enlarged sectional view of a portion A of the nonaqueous electrolyte battery shown in FIG. FIG. 3 is an exploded perspective view of another example of the nonaqueous 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 is to be noted that the same reference numerals are given to the same components throughout the embodiments, and redundant description will be omitted. In addition, each drawing is a schematic diagram for promoting the explanation and understanding of the embodiment, and the shape, dimensions, ratio, and the like are different from the actual device. In consideration of the above, the design can be changed as appropriate.

(1st Embodiment)
According to a 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 having a plurality of Al binding energy peaks in the range of 70 eV to 78 eV in the X-ray photoelectron spectroscopy spectrum. The positive electrode active material-containing layer satisfies the following formula (1).

0 <H / (G + H) ≦ 0.1 (1)
Here, G is a 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.

A positive electrode active material containing a lithium manganese composite oxide and lithium cobalt oxide is brought into contact with a compound generated by a reaction between a nonaqueous electrolyte and a trace amount of water, which is an unavoidable impurity, such as hydrofluoric acid (HF). For example, a gas such as hydrogen or carbon monoxide is generated. Due to such gas generation, for example, in a non-aqueous electrolyte battery including a positive electrode including the above-described positive electrode active material, the internal resistance increases due to expansion of the non-aqueous electrolyte battery. Thereby, the safety of the nonaqueous electrolyte battery may be reduced.

Therefore, the positive electrode active material-containing layer has a surface where a plurality of peaks of the binding energy of Al in the X-ray photoelectron spectroscopy spectrum are in the range of 70 eV to 78 eV. This surface can prevent direct contact between the positive electrode active material and a compound generated by a reaction between the nonaqueous electrolyte and moisture. As a result, gas generation can be suppressed.

(4) 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 a gas, the generated gas can be absorbed.

Therefore, the positive electrode active material-containing layer has a surface where a plurality of peaks of Al binding energy in the X-ray photoelectron spectroscopy spectrum are in the range of 70 eV or more and 78 eV or less, and satisfies the expression (1) to reduce gas generation. Can be suppressed.

It is preferable 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 a range of 70 eV or more and less than 75 eV and in a range of 75 eV or more and 78 eV or less. .

Since the positive electrode active material-containing layer having a surface that satisfies this has a surface including a bond between Al and O and a bond between Al and F, the layer is generated by a reaction between the positive electrode active material, the nonaqueous electrolyte, and moisture. The effect of preventing direct contact with the compound is higher. 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 within the range of the binding energy of Al of 70 eV or more and less than 75 eV. B is the maximum peak height of the X-ray photoelectron spectroscopy spectrum in the range of Al binding energy of 75 eV or more and 78 eV or less. C is the average peak height of the X-ray photoelectron spectroscopy spectrum in the range of the binding energy of Al of 65 eV or more and less than 70 eV.

Since the positive electrode active material-containing layer having a surface that satisfies this condition has a surface containing a predetermined ratio of a bond between Al and O and a bond between Al and F, the positive electrode active material, the nonaqueous electrolyte, The effect of preventing direct contact with the compound generated by the above reaction is further enhanced. 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 spectroscopy spectrum in the range of the binding energy of Mn of 638 eV or more and 645 eV or less. E is the average peak height of the X-ray photoelectron spectroscopy spectrum in the range of 635 eV to less than 638 eV of the binding energy of Mn.

正極 The positive electrode active material-containing layer having a surface that satisfies the above condition has a surface containing a predetermined ratio of Al and F bonds to Mn and O bonds. Therefore, it is possible to prevent direct contact between the positive electrode active material and the compound generated by the reaction between the non-aqueous electrolyte and the water without significantly lowering the conductivity of Li ions 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, Desirably, 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 direct contact between the positive electrode active material and a compound generated by a reaction between the nonaqueous electrolyte and moisture. And the effect of suppressing gas generation is extremely high. As a result, gas generation can be significantly suppressed.

正極 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 or both surfaces 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 include a conductive agent and a binder.

The positive electrode active material includes 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. M is more preferably Al. More preferably, the lithium manganese composite oxide has a spinel type crystal structure.

Lithium cobaltate preferably has a composition formula of Li _x CoO ₂ . Here, the suffix x is preferably in the range of 0 <x ≦ 1.

The positive electrode active material-containing layer preferably satisfies the following equation.
0 <H / (G + H) ≦ 0.1 (1)
Here, G is a 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.

した As described above, the positive electrode active material-containing layer can suppress gas generation by satisfying the expression (1). The reason is described below. When H / (G + H) is larger than 0.1, the amount of lithium cobalt oxide weak to a 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 being unable to suppress gas generation, the charge / discharge cycle performance is reduced. When H / (G + H) is 0, that is, when lithium cobaltate is not included in the positive electrode active material, for example, the positive electrode active material cannot absorb gas inevitably generated by the reaction between the nonaqueous electrolyte and moisture. , Gas generation cannot be suppressed.

The positive electrode active material is, for example, in the form of particles. When the positive electrode active material is in the form of particles, the positive electrode active material may be primary particles, or may be secondary particles obtained by aggregating primary particles.

粒子 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 diameter (secondary particle diameter) 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 obtained by agglomeration of primary particles, but are preferably mainly composed of primary particles. The average primary particle diameter of the lithium cobalt oxide particles is preferably 6 μm or more and 12 μm or less.

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

The conductive agent can increase the electronic conductivity and suppress the contact resistance with the current collector. Examples of the conductive agent include a carbon material such as acetylene black, carbon black, graphite, carbon nanofiber, or carbon nanotube. The kind of the conductive agent used can be one kind or two or more kinds.

The binder can bind the active material and the conductive agent. Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluorine-based rubber. The kind of the binder used can be one kind or two or more kinds.

(4) The positive electrode active material-containing layer has a surface in which a plurality of peaks of Al binding energy in an X-ray photoelectron spectroscopy spectrum are in the range of 70 eV to 78 eV. This surface can be, for example, a coating formed on the positive electrode active material-containing layer. The peak of the binding energy of Al may be two or three or more within the range of 70 eV to 78 eV. 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. No major surface.

(4) The positive electrode active material-containing layer preferably has at least one peak 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 in the binding energy of Al. The peak of the binding energy of Al in the range of 70 eV or more and less than 75 eV indicates that there is a bond between Al and O. The peak of the binding energy of Al in the range of 75 eV or more and 78 eV or less indicates that there is a bond between Al and F. There may be one peak 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.

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

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

As described above, by satisfying the expression (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, the film on the surface of the positive electrode active material-containing layer contains bonding between Al and F moderately, so While maintaining the discharge performance, it is possible to suppress the reaction between the compound inevitably generated by the reaction between the nonaqueous electrolyte and the water and the positive electrode active material-containing layer. As a result, it is considered that an increase in internal resistance and generation of gas can be suppressed.

More preferably, the positive electrode active material-containing layer satisfies the following expression.
0.004 ≦ (BC) / (DE) ≦ 0.04 (3)
Here, D is the maximum peak height of the X-ray photoelectron spectrum within the range of the binding energy of Mn from 638 eV to 645 eV. E is the average peak height of the X-ray photoelectron spectrum in the range of 635 eV to 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 there is a bond between Mn and O. The maximum peak height within the range of 638 eV or more and 645 eV or less is the peak height of the highest peak height spectral data in continuous spectral data within the range of the X-ray photoelectron spectroscopy spectrum. The average peak height is a peak height obtained by averaging the peak heights of continuous X-ray photoelectron spectroscopy spectral data within the range of 635 eV to less than 638 eV.

As described above, by satisfying the expression (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 Al and F are sufficiently bonded in the film of No. This coating maintains the ionic conductivity of the Li ions of the positive electrode, that is, the reaction between the compound inevitably generated by the reaction between the nonaqueous electrolyte and the water and the positive electrode active material-containing layer while maintaining the charge / discharge performance. It is thought that it can be suppressed.

The positive electrode current collector is desirably formed from 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 aluminum alloy foil can be dramatically increased, and the density of the positive electrode can be increased with a high press pressure, thereby increasing the battery capacity. Can be done.

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

配合 The mixing 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.

(4) The positive electrode active material-containing layer preferably has a porosity of 20% or more and 50% or less. A positive electrode provided with a positive electrode active material-containing layer having such a porosity has high density and excellent affinity with a nonaqueous electrolyte. More preferable porosity is 25% or more and 40% or less.

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

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

<How to remove the positive electrode>
The battery is completely discharged to bring the state of charge (SOC) to 0%. This battery is disassembled, and the positive electrode is cut out to about 2 cm square. The cut positive electrode is immersed in 50 cc (cm ³ ) of ethyl methyl carbonate and left for 1 hour. Thereafter, in order to dry the positive electrode, vacuum drying is performed for one hour to obtain a measurement sample. The operations so far are performed in a glove box in an argon atmosphere.

<Method of measuring 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 obtained powder is washed with acetone and dried. The obtained powder is dissolved in hydrochloric acid, the conductive agent is removed by filtration, then diluted with ion-exchanged water, and the metal content is calculated by inductively coupled plasma emission spectroscopy. At the same time, the presence of the lithium manganese composite oxide and lithium cobalt oxide is confirmed by X-ray diffraction and SEM-EDX. Calculate the respective chemical formulas and formula weights of the lithium manganese composite oxide and the lithium cobaltate from the obtained metal ratio, and calculate the weight ratio of the lithium manganese composite oxide and the lithium cobaltate contained in the collected positive electrode active material-containing layer of a predetermined weight. Ask. The obtained values are G and H.

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

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

(4) As the excitation X-ray source, use is made of single-crystal spectral AlKα rays (light obtained by dispersing AlKα rays with a single crystal for better monochromaticity). 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 the 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, information from the surface of the positive electrode active material containing layer to a depth of 0 to 10 nm can be obtained. In other words, it can be said that the X-ray photoelectron spectroscopy spectrum of the positive electrode active material containing layer is a spectrum of 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, which appears in the binding energy region of 70 eV or more and less than 75 eV, 2p of Al, which appears 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 orbit 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 belonging to the 2p _3/2 orbital of Ti, which appears in the binding energy region of 638 eV or more and less than 645 eV, is determined, and the bond of 635 eV or more and less than 638 eV The average peak intensity E is calculated from the peak in the energy region.

<Method of manufacturing positive electrode>
In the production of the positive electrode, first, 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 form a positive electrode active material-containing layer. After making, press is applied. In addition, the positive electrode active material, the positive electrode conductive agent, and the binder may be formed in a pellet shape 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 Al binding energy in the X-ray photoelectron spectroscopy spectrum are in the range of 70 eV or more and 78 eV or less is, for example, due to 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 film formed on the surface of the positive electrode active material-containing layer will be described.

Using the positive electrode manufactured as described above, for example, a nonaqueous electrolyte battery including a negative electrode and a nonaqueous electrolyte is manufactured. In order to form a predetermined film on the surface of the positive electrode, it is preferable that at least one of the nonaqueous 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 from 0.001 mol / L to 0.1 mol / L, and more preferably from 0.002 mol / L to 0.03 mol / L. In addition, the positive electrode active material preferably includes 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 from an aluminum foil or an aluminum alloy foil.

(4) Aging is performed on the produced nonaqueous electrolyte battery at a high temperature (for example, 70 ° C.) for a long time (for example, 24 hours) in a charged state after the initial charge. An example of these adjustments is the aging condition described in the embodiment. By doing so, the composition of the film formed on the surface of the positive electrode active material-containing layer can be adjusted.

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 having a plurality of Al binding energy peaks in the range of 70 eV to 78 eV in the X-ray photoelectron spectroscopy spectrum. The positive electrode active material-containing layer satisfies the relational expression of 0 <H / (G + H) ≦ 0.1.

ため With such a configuration, in the positive electrode according to the first embodiment, gas generation can be suppressed and a rise in resistance can be suppressed.

(Second embodiment)

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

正極 For the positive electrode, for example, the positive electrode of the first embodiment is used. The positive electrode current collector may include a portion where the surface does not support the positive electrode active material-containing layer. 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 the 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 or both surfaces. In addition, the negative electrode current collector can include a portion where the surface does not support the negative electrode active material-containing layer. 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.

(4) 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 with a separator interposed therebetween, for example.

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

非 The nonaqueous electrolyte battery according to the second embodiment can further include a positive electrode terminal and a negative electrode terminal. The positive electrode terminal can function as a conductor for electrons to move between the positive electrode and the external terminal by being electrically connected to a part of the positive electrode. 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 function as a conductor for electrons to move between the negative electrode and the external terminal by being electrically connected 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 contains the electrode group and the non-aqueous electrolyte. The non-aqueous electrolyte may 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.

正極 For 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 surfaces 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, orthorhombic-type titanium-containing oxides, and monoclinic titanium-containing oxides. Includes 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 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. Examples of the lithium titanium oxide include lithium titanate having a spinel structure (for example, Li _{4 + x} Ti ₅ O ₁₂ (x is a value that changes by charging and discharging, 0 ≦ x ≦ 3)), and ramsdellite-type titanic acid. Lithium (for example, Li _{2 + y} Ti ₃ O ₇ (y is a value that changes depending on charge and discharge, 0 ≦ y ≦ 3)) and the like can be given. On the other hand, the molar ratio of oxygen is formally shown as ₁₂ in spinel type Li _{4 + x} Ti ₅ O ₁₂ and ₇ in ramsdellite type Li _{2 + y} Ti ₃ O ₇ , but these are influenced by oxygen nonstoichiometry and the like. Can vary.

Examples of metal composite oxides containing Ti and at least one element selected from the group consisting of P, V, Sn, Cu, Ni, Nb and Fe include, for example, TiO ₂ —P ₂ O ₅ , TiO ₂ _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 ). It is preferable that the metal composite oxide has low crystallinity, and has a microstructure in which a crystalline phase and an amorphous phase coexist or an amorphous phase exists alone. With such a microstructure, cycle performance can be significantly improved.

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

The orthorhombic titanium-containing oxide is represented by a 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} , where M3 is composed of Zr, Si, Sn, Fe, Co, Mn and Ni. At least one selected from the group; M4 is a compound selected from the group consisting of V, Nb, Ta, Mo, W and Bi, and 0 ≦ x ≦ 5, 0 ≦ y <1, 0 ≦ z ≦ 2, −0.3 ≦ δ ≦ 0.3.

(4) A preferable negative electrode active material contains a lithium titanium composite oxide.

A negative electrode containing a titanium-containing oxide such as a lithium-titanium composite oxide has a Li occlusion potential of 0.4 V (vs. Li / Li ⁺ ) or higher. The precipitation of metallic lithium on the above can be prevented. The negative electrode active material may contain an active material other than the lithium-titanium composite oxide. In this case, use an active material having a Li storage potential of 0.4 V (vs. Li / Li ⁺ ) or more. Is desirable.

Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine-based rubber, styrene-butadiene rubber (SBR), carboxymethylcellulose (CMC), polyimide, and polyamide. The kind of the binder can be one kind or two or more kinds.

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 kind of the conductive agent can be one kind or two or more kinds.

The mixing 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 preferable that the content be at least 28% by weight. By blending the conductive agent in a proportion of 2% by weight or more, excellent large current characteristics due to high current collecting performance can be obtained. When the amount of the binder is 2% by weight or more, the binding property between the negative electrode active material-containing layer and the negative electrode current collector can be increased, and the cycle characteristics can be improved. On the other hand, from the viewpoint of increasing the capacity, each of the negative electrode conductive agent and the binder is preferably 28% by weight or less.

The current collector is preferably an aluminum foil or an aluminum alloy foil which 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 form 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 a pellet shape 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 is excellent in affinity with the nonaqueous electrolyte and can achieve high density. More preferable porosity is 25% or more and 40% or less.

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

<Non-aqueous electrolyte>
Examples of the non-aqueous electrolyte include a liquid non-aqueous electrolyte prepared by dissolving the electrolyte in a non-aqueous solvent, and a gel non-aqueous electrolyte obtained by combining a liquid non-aqueous electrolyte and a polymer material.

The electrolyte is, 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 trifluorometasulfonic acid (LiCF ₃ SO ₃ ), lithium bistrifluoromethylsulfonylimide [LiN (CF ₃ SO ₂ ) ₂ ], lithium aluminum tetrafluoride (LiAlF ₄ ) Can be mentioned. These electrolytes may be used alone or in combination of two or more. The electrolyte preferably contains lithium hexafluorophosphate or lithium aluminum tetrafluoride, and more preferably contains lithium hexafluorophosphate and lithium aluminum tetrafluoride.

(4) The electrolyte is preferably dissolved in the nonaqueous solvent in a range of 0.5 mol / L to 2.5 mol / L.

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

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

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

<Exterior material>
The exterior member may be formed from a laminate film or a metal container. If a metal container is used, the lid can be integral with or separate from the container. The thickness of the metal container is more preferably 0.5 mm or less, and more preferably 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 mounted on a portable electronic device or the like, a large battery mounted on a two-wheeled or four-wheeled vehicle may be used.

外装 The thickness of the laminate film exterior member is desirably 0.2 mm or less. Examples of the laminate film include a multilayer film including a resin film and a metal layer disposed between the resin films. The metal layer is preferably an aluminum foil or an aluminum alloy foil for weight reduction. For the resin film, for example, a polymer material such as polypropylene (PP), polyethylene (PE), nylon, or polyethylene terephthalate (PET) can be used. The laminate film can be formed into a shape of an exterior member by performing sealing by heat fusion.

The metal container is made of aluminum or aluminum alloy. As the aluminum alloy, an alloy containing an element such as magnesium, zinc, or silicon is preferable. In aluminum or an aluminum alloy, the content of transition metals such as iron, copper, nickel, and chromium is preferably 100 ppm or less in order to dramatically improve long-term reliability and heat dissipation under a high-temperature environment.

金属 The metal container made of aluminum or an aluminum alloy preferably has an average crystal grain size of 50 μm or less, more preferably 30 μm or less, and still more preferably 5 μm or less. By setting the average crystal grain size to 50 μm or less, the strength of a metal container made of aluminum or an aluminum alloy can be remarkably increased, and the thickness of the container can be further reduced. As a result, it is possible to realize a nonaqueous electrolyte battery that is lightweight, has a high output, and is excellent in long-term reliability and is suitable for a vehicle or the like.

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

First, a nonaqueous electrolyte battery of a 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 the nonaqueous electrolyte battery according to the second embodiment. FIG. 2 is an enlarged sectional view of a portion A of the nonaqueous electrolyte battery shown in FIG.

非 The nonaqueous electrolyte battery 100 shown in FIGS. 1 and 2 includes a flat electrode group 1 and a package 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. The flat electrode group 1 is formed by winding a negative electrode 2 and a positive electrode 3 into a flat shape with a separator 4 interposed therebetween.

(2) 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 a portion located on the outermost side of the negative electrode 2, a negative electrode active material-containing layer 22 is formed on a main surface of the two main surfaces of the negative electrode current collector 21 not facing the positive electrode 3. Not carried. In other portions 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.

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

(4) The electrode group 1 is housed in the exterior member 7 made of a laminated film with the ends of the negative terminal 5 and the positive terminal 6 extending from the exterior member 7. A non-aqueous electrolyte (not shown) is accommodated in the exterior member 7 made of a laminate film. The non-aqueous electrolyte is impregnated in the electrode group 1. The exterior member 7 made of a laminate film is sealed by heat-sealing the end portion and the two end portions 71 orthogonal to the end portion with the negative electrode terminal 5 and the positive electrode terminal 6 sandwiched at one end. Have been.

Next, a second example of the nonaqueous electrolyte battery according to the embodiment will be described with reference to FIG.

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

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

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

The lid 8 has a sealing plate 81. The sealing plate 81 is desirably 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 concave portion provided on the sealing plate 81. The portion of the sealing plate 81 where the groove 83 is provided is particularly thin. Therefore, when the internal pressure of the container main body 7 increases, the groove 83 can be broken to release the gas in the container main body 7 to the outside.

口 In addition to the safety valve 82, the sealing plate 81 is provided with a liquid injection hole 81a. 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, a positive electrode and a 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 belt-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 each having no positive electrode active material-containing layer formed on the surface. The plurality of positive electrode current collection tabs 33 extend from the end face of the electrode group 1 facing the lid 8. In FIG. 3, the plurality of positive electrode current collecting tabs 33 are described as one member 33 which is an aggregate.

The negative electrode includes a strip-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 each having no negative electrode active material-containing layer formed on the surface. The plurality of negative electrode current collection tabs 23 extend from the end face of the electrode group 1 facing the lid 8. In FIG. 3, the plurality of negative electrode current collecting 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 terminal 84 and the negative terminal 85, two external insulating materials 86, and two internal insulating materials.

(4) The positive terminal 84 and the negative terminal 85 are electrically insulated from the sealing plate 81, respectively. 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 terminal lead 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 nonaqueous electrolyte battery 100 shown in FIG. 3, the injection hole 81 a provided in the sealing plate 81 forms a liquid injection passage for injecting the nonaqueous electrolyte from the outside into the inside of the nonaqueous electrolyte battery 100. I have. 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.

非 In the nonaqueous 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. The terminal lead 87 electrically connected to the negative terminal 85 is electrically connected to the negative current collecting tab 23.

非 Since the nonaqueous electrolyte battery according to the second embodiment includes the positive electrode according to the first embodiment, gas generation in the battery and an increase in battery resistance can be suppressed.

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

A plurality of non-aqueous electrolyte batteries can be electrically connected in series, in parallel, or in a combination of series and 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 charging and discharging of the nonaqueous electrolyte battery. Further, a circuit included in a device (for example, an electronic device, an automobile, or the like) that uses the battery pack as a power supply can be used as a protection circuit for the battery pack.

(4) The battery pack may further include an external terminal for energization. The external terminals for energization are for outputting a current from the nonaqueous electrolyte battery to the outside and for inputting a current to the nonaqueous electrolyte battery. In other words, when the battery pack is used as a power supply, a current is supplied to the outside through an external terminal for conduction. Further, when charging the battery pack, a charging current (including regenerative energy of the power of the vehicle) is supplied to the battery pack through an external terminal for power supply.

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 structure shown in FIGS.

The plurality of cells 100 are stacked 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 the adhesive tape 122, thereby forming the assembled battery 123. ing. These cells 100 are electrically connected to each other in series as shown in FIG.

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

A positive electrode lead 128 is connected to the positive electrode external terminal 6 of the cell 100 located at the lowermost layer of the assembled battery 123, and the tip is inserted into the positive electrode connector 129 of the printed wiring board 124 and electrically connected. I have. The negative electrode-side lead 130 is connected to the negative electrode external terminal 5 of the unit cell 100 located on the uppermost layer of the assembled battery 123, and the tip is inserted into the negative electrode-side connector 131 of the printed wiring board 124 to be electrically connected. I have. These

connectors

129 and 131 are connected to the protection circuit 126 through

wirings

132 and 133 formed on the printed wiring board 124, respectively.

The thermistor 125 detects the temperature of each of the cells 100 and transmits a detection signal to the protection circuit 126. The protection circuit 126 can cut off the plus side wiring 134a and the minus side wiring 134b between the protection circuit 126 and the terminal 127 for energizing the external device under a predetermined condition. An example of the predetermined condition is when a signal indicating that the temperature of the cell 100 is equal to or higher than the predetermined temperature is received from the thermistor 125, for example. Another example of the predetermined condition is when overcharge, overdischarge, overcurrent, or the like of the cell 100 is detected. The detection of the overcharge or the like is performed for each single cell 100 or the whole single cell 100. When detecting the individual cells 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 unit cell 100. In the battery pack 200 of FIG. 4 and FIG. 5, wiring 135 for voltage detection is connected to each of the cells 100, and a detection signal is transmitted to the protection circuit 126 through these wirings 135.

保護 A protective sheet 136 made of rubber or resin is disposed on each of three sides of the battery pack 123 except for the side from which the positive external terminal 6 and the negative external terminal 5 protrude.

(4) The battery pack 123 is stored in the storage container 137 together with the protective sheets 136 and the printed wiring board 124. That is, the protective sheets 136 are disposed on both the inner surfaces in the long side direction and the inner surfaces in the short side direction of the storage container 137, and the printed wiring board 124 is disposed on the inner surface on the opposite side in the short side direction. I have. The assembled battery 123 is located in a space surrounded by the protection sheet 136 and the printed wiring board 124. The lid 138 is attached to the upper surface of the storage container 137.

Note that a heat-shrinkable tape may be used instead of the adhesive tape 122 for fixing the battery assembly 123. In this case, the protective sheets are arranged on both sides of the battery pack, and the heat-shrinkable tube is made to rotate. Then, the heat-shrinkable tube is heat-shrinked to bind the battery pack.

Although the battery pack 200 shown in FIGS. 4 and 5 has a configuration in which a plurality of unit cells 100 are connected in series, the battery pack according to the third embodiment includes a plurality of unit 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 unit 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.

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

態様 The form of battery pack 200 is appropriately changed depending on the application. As a use of the battery pack 200, a battery in which cycle characteristics with large current characteristics are desired is preferable. Specific examples include a power source for a digital camera, a two-wheel or four-wheel hybrid electric vehicle, a two-wheel or four-wheel electric vehicle, and an on-board vehicle such as an assist bicycle. In particular, the on-vehicle use is preferable.

自動車 In the vehicle equipped with the battery pack according to the present embodiment, the battery pack is for recovering, for example, regenerative energy of the power of the vehicle.

電池 The battery pack of the third embodiment includes the nonaqueous electrolyte battery of the first embodiment. Therefore, the battery pack according to the third embodiment can suppress generation of gas in the battery and an 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 without departing from the gist of the invention.

(Example 1)
In Example 1, the positive electrode and the nonaqueous 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 And the particles were prepared. The LMO particles contained secondary particles, and the average secondary particle diameter was 10 μm. The average particle size of the LCO primary particles was 8 μm. In addition, acetylene black and graphite as conductive agents, and polyvinylidene fluoride (PVdF) as binders were prepared. These were added and mixed with N-methylpyrrolidone (NMP) such 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 surfaces of a current collector made of an aluminum foil having a thickness of 15 μm, dried, and then pressed to produce a positive electrode having a positive electrode active material-containing layer having a basis weight of 80 g / m ^{2 on} one surface.

<Preparation of negative electrode>
As the negative electrode active material, spinel type lithium titanate (LTO) particles represented by the composition formula Li ₄ Ti ₅ O ₁₂ were prepared. In addition, graphite as a conductive agent and PVdF as a binder were prepared. These were added to NMP and mixed such 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 surfaces of a current collector made of an aluminum foil having a thickness of 15 μm, dried, and then pressed to produce a negative electrode having a negative electrode active material-containing layer having a basis weight of 40 g / m ² on one surface.

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

<Preparation of non-aqueous electrolyte>
Ethyl methyl carbonate (EMC) and ethylene carbonate (EC) were mixed at a volume ratio of 1: 1 to prepare a mixed solvent. In this mixed solvent, 1.0 mol / L lithium hexafluorophosphate (LiPF ₆ ) and 0.01 mol / L lithium aluminum tetrafluoride (LiAlF ₄ ) were dissolved to prepare a non-aqueous electrolyte.

<Production of battery>
The flat electrode group produced as described above was inserted into a bottomed rectangular cylindrical can (outer container) made of aluminum having a thickness of 0.3 mm.

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

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

Thus, a 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 manufactured.

(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 manufactured.

(Example 4)
In Example 4, as shown in Table 1, except for using particles of LMO represented by a composition formula _LiMn 1.8 _Al 0.2 _{O 4} in the same manner as in Example 1, a non-embodiment 4 A water electrolyte battery was manufactured.

(Example 5)
In Example 5, as shown in Table 1, for the use of the particles of the LMO represented by a composition formula _LiMn 1.8 _Al 0.2 _{O 4,} and LiAlF ₄ was dissolved at a concentration of 0.002 mol / L A 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, except that particles of LMO represented by the composition formula LiMn _1.6 Al _0.4 O ₄ were used, A water electrolyte battery was manufactured.

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

(Example 8)
In Example 8, as shown in Table 1, a 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 manufactured.

(Example 10)
In Example 10, after injecting and sealing under reduced pressure in the same manner as in Example 1, the voltage after sealing was adjusted to 2.4 V by charging at a 1C rate in an environment of 25 ° C. Next, it was left in a constant temperature bath at 70 ° C. for 24 hours to perform aging. After aging, the outer container was opened, and sealed again under a reduced pressure environment of -90 kPa to produce a nonaqueous 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 Example 1 was repeated except that LiAlF ₄ was not added. After injecting and sealing under reduced pressure in the same manner as described above, the one after sealing was adjusted to 2.4 V by charging at a 1C rate in a 25 ° C. environment. Next, it was left in a constant temperature bath at 70 ° C. for 24 hours to perform aging. After aging, the outer container was opened and sealed again under a reduced pressure environment of -90 kPa, to produce a nonaqueous electrolyte battery of Example 11.

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

(X-ray photoelectron spectroscopy measurement of positive electrode surface)
FIGS. 6 and 7 show the results of subjecting the surface of the positive electrode active material-containing layer provided in the nonaqueous electrolyte battery of Example 7 to X-ray photoelectron spectroscopy measurement according to the method described above. The spectra shown in FIGS. 6 and 7 are actually measured XPS spectra. The horizontal axis is binding energy eV. 6 is counts / s (Resid × 2) (Counts / s (Resid × 2)), and the vertical scale of the residual is 2. The vertical axis of FIG. (Residual × 5) (Counts / s (Resid × 5)), and the magnification of the vertical axis of the residual is 5. From the spectrum shown in Fig. 6, a binding energy region in the range of 70 eV to 78 eV. Contains two peaks P1 and P2 attributed to electrons in the 2p orbit of Al.

The spectrum shown in FIG. 6 has a peak P1 having a maximum peak height in the range of 70 eV or more and less than 75 eV with an Al binding energy of 73.6 eV, and a peak having a 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 peak P2 attributed to electrons 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 Mn binding energy of the peak P3 having the maximum peak height in the range of 638 eV to 645 eV was 642.5 eV. Thus, it can be seen that one region of the binding energy within the range of 638 eV or more and 645 eV or less contains one peak P3 attributed to the electron in the 2p3 _{/ 2} orbit of Mn.

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

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 a binding energy region of 70 eV or more and 78 eV or less, in a range of 70 eV or more and less than 75 eV. And that the binding energy in the range of 75 eV or more and 78 eV or less includes one peak each belonging to an electron in the 2p orbit of Al. The binding energy in the range of 638 eV or more and 645 eV or less contains Mn It was confirmed that one peak attributed to 2p _3/2 orbital electrons was included, and that each element of Li, C, O, F, P, Ti, and Co was included in the positive electrode active material containing layer. confirmed.

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

(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 50% SOC, a voltage when a current of 1 C and 10 C was continuously passed for 0.2 seconds each in an environment of 25 ° C. Table 2 shows the 0.2 second resistance calculated by the following formulas when V1 and V2 are V1 and V2.
0.2 second resistance (Ω) = (V1-V2) / (10-1)

(Cell thickness after storage and 0.2 second discharge resistance)
Each of the nonaqueous electrolyte batteries of Examples 1 to 11 and Comparative Example 1 was adjusted to an SOC of 100% and stored at 75 ° C. for one week. After storage, the cell thickness was measured under a 25 ° C. environment, and the difference (mm) from the cell thickness before storage was calculated.

Table 2 shows the results of measuring the 0.2 second discharge resistance of each of the nonaqueous electrolyte batteries of Examples 1 to 11 and Comparative Example 1 at 25 ° C after storage.

As shown in Table 2, the non-aqueous electrolyte batteries of Examples 1 to 11 had 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 exhibited the same 0.2-second resistance as that of Comparative Example 1 and the 0.2-second resistance after storage.

From these results, it can be seen that the nonaqueous electrolyte batteries of Examples 1 to 11 suppress gas generation as compared with the nonaqueous electrolyte batteries of Comparative Example 1. This is considered to be because the nonaqueous electrolyte battery of Comparative Example 1 did not contain LiCoO _{2 in the} positive electrode active material, so that the generated gas could not be absorbed.

Further, the non-aqueous electrolyte batteries of Examples 1 to 7 all had small cell thickness after storage, discharge resistance for 0.2 second, and resistance for 0.2 second after storage. This means that (BC) / (AC) is in the range of 0.3 or more and 2 or less, and that (BC) / (DE) is 0.004 or more and 0.04 or less. It is considered that when the content is within the range, gas generation was suppressed without the Li ion conductivity of the positive electrode being significantly reduced by the coating formed on the positive electrode active material-containing layer.

That is, the positive electrode according to at least one of the embodiments and examples described above includes a positive electrode active material-containing layer containing a positive electrode active material including a lithium manganese composite oxide and lithium cobalt oxide, and includes a positive electrode active material-containing layer. Has a surface with a plurality of Al binding energy peaks in the range of 70 eV to 78 eV in the X-ray photoelectron spectroscopy spectrum, 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 nonaqueous 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 have been presented by way of example only, and are not intended to limit the scope of the inventions. These new embodiments can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

Claims

Includes a positive electrode active material-containing layer containing a positive electrode active material containing lithium manganese composite oxide and lithium cobalt oxide,
The positive electrode active material-containing layer has a surface having a plurality of peaks of Al binding energy in the range of 70 eV or more and 78 eV or less in an X-ray photoelectron spectroscopy spectrum,
Positive electrode satisfying the following formula (1):
0 <H / (G + H) ≦ 0.1 (1)
Here, G is a weight ratio of the lithium manganese composite oxide in the positive electrode active material, and H is a weight ratio of the lithium cobalt oxide in the positive electrode active material.
The positive electrode active material-containing layer, wherein the plurality of peaks of the binding energy of Al in the X-ray photoelectron spectroscopy spectrum are each at least one in a range of 70 eV or more and less than 75 eV and in a range of 75 eV or more and 78 eV or less. The positive electrode according to claim 1, comprising:
The positive electrode according to claim 1 or 2, wherein the following formula (2) is satisfied:
0.3 ≦ (BC) / (AC) ≦ 2 (2)
Here, A is the maximum peak height of the X-ray photoelectron spectroscopy spectrum within the range of Al binding energy of 70 eV or more and less than 75 eV,
B is the maximum peak height of the X-ray photoelectron spectroscopy spectrum in the range of 75 eV to 78 eV of the binding energy of Al;
C is the average peak height of the X-ray photoelectron spectroscopy spectrum within the range of Al binding energy of 65 eV or more and less than 70 eV.
The positive electrode according to any one of claims 1 to 3, 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 spectroscopy spectrum in the range of the binding energy of Mn of 638 eV or more and 645 eV or less,
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 5. The positive electrode according to claim 1, wherein the positive electrode 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 according to any one of claims 1 to 5, a negative electrode, and a non-aqueous electrolyte.
A battery pack comprising the nonaqueous electrolyte battery according to claim 6.