JP2019040890A - Positive electrode - Google Patents

Abstract

To provide a nonaqueous electrolyte battery which can exhibit good charge/discharge cycle characteristics.SOLUTION: A nonaqueous electrolyte battery 1 is provided according to an embodiment hereof. The nonaqueous electrolyte battery 1 comprises: a positive electrode 6; a negative electrode 7; and a nonaqueous electrolyte. The positive electrode 6 includes: a positive electrode current collector 61; and a layer 62 of a positive electrode active material formed on the positive electrode current collector 61. The positive electrode active material-containing layer 62 includes at least, one kind of a lithium nickel composite oxide and a conducting agent. In a particle size distribution obtained by a laser diffractive scattering method, the positive electrode active material-containing layer 62 has an average particle diameter dwithin a range of 1 μm or more and 5.5 μm or less, a maximum particle size within a range of 10 μm or more and 100 μm or less, and a particle size dwithin a range of 0.5 μm or more and 3 μm or less when its cumulative frequency from a small particle size side becomes 10%; X is in a range of 0.5 or more and below 1, where X=(d-d)/d.SELECTED DRAWING: Figure 5

Description

  Embodiments of the present invention relate to a positive electrode.

  Lithium ion secondary batteries, which are non-aqueous electrolyte batteries, are introduced and popularized in electronic devices such as smartphones and notebook personal computers, and vehicles such as hybrid vehicles, plug-in hybrid vehicles, and electric vehicles. Lithium ion secondary batteries include, for example, an electrode group formed by laminating a positive electrode and a negative electrode through a separator, or an electrode group obtained by winding a laminate formed in this manner, using aluminum or an aluminum alloy. It can be produced by storing in a container containing the material and injecting an electrolyte prepared by dissolving an electrolytic salt containing lithium in a non-aqueous solvent into the container.

  Lithium ion secondary batteries have important issues of increasing capacity and extending their life, and it is desired that they have high capacity and good charge / discharge cycle characteristics.

  One measure for increasing the capacity of a lithium ion secondary battery is to use a lithium nickel composite oxide as a positive electrode active material. However, the lithium nickel composite oxide has a drawback that side reactions are likely to occur on the electrode, and the capacity can be reduced by repeated cycles.

JP 2012-9276 A JP 2002-141060 A JP 2011-181387 A

  The problem to be solved by the present invention is to provide a nonaqueous electrolyte battery capable of exhibiting good charge / discharge cycle characteristics.

According to an embodiment, a non-aqueous electrolyte battery is provided. The nonaqueous electrolyte battery includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. The positive electrode includes a positive electrode current collector and a positive electrode active material-containing layer formed on the positive electrode current collector. The positive electrode active material-containing layer includes at least one lithium nickel composite oxide and a conductive agent. The particle diameter of the conductive agent is smaller than the average particle diameter of at least one lithium nickel composite oxide. In the particle size distribution obtained by the laser diffraction scattering method, the positive electrode active material-containing layer has an average particle diameter d _{50 in} the range of 1 μm to 5.5 μm and a maximum particle diameter in the range of 10 μm to 100 μm. The particle diameter d _{10 at} which the cumulative frequency from the small particle diameter side becomes 10% is in the range of 0.5 μm to 3 μm. X represented by X = (d ₅₀ −d ₁₀ ) / d _{50 is} in the range of 0.5 or more and less than 1.

FIG. 1 is a schematic cutaway perspective view of an example nonaqueous electrolyte battery according to an embodiment. FIG. 2 is a schematic cross-sectional view of a part A shown in FIG. FIG. 3 is a schematic plan view of a positive electrode included in an example nonaqueous electrolyte battery according to the embodiment. FIG. 4 is a schematic cross-sectional view of an example of an electrode group that can be included in the nonaqueous electrolyte battery according to the embodiment. FIG. 5 is a particle size distribution of the positive electrode active material-containing layer of the positive electrode included in the nonaqueous electrolyte battery of Example 1 and Comparative Example 1.

  Hereinafter, embodiments will be described with reference to the drawings. In addition, the same code | symbol shall be attached | subjected to a common structure through embodiment, and the overlapping description is abbreviate | omitted. Each figure is a schematic diagram for encouraging explanation and understanding of the embodiment, and its shape, dimensions, ratio, etc. are different from the actual apparatus, but these are the following explanations and known techniques. In consideration of the above, the design can be changed as appropriate.

[Embodiment]
According to an embodiment, a non-aqueous electrolyte battery is provided. The nonaqueous electrolyte battery includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. The positive electrode includes a positive electrode current collector and a positive electrode active material-containing layer formed on the positive electrode current collector. The positive electrode active material-containing layer includes at least one lithium nickel composite oxide and a conductive agent. In the particle size distribution obtained by the laser diffraction scattering method, the positive electrode active material-containing layer has an average particle diameter d _{50 in} the range of 1 μm to 5.5 μm and a maximum particle diameter in the range of 10 μm to 100 μm. The particle diameter d _{10 at} which the cumulative frequency from the small particle diameter side becomes 10% is in the range of 0.5 μm to 3 μm. X represented by X = (d ₅₀ −d ₁₀ ) / d _{50 is} in the range of 0.5 or more and less than 1.

  When used in the positive electrode, the lithium nickel composite oxide can function as a positive electrode active material. A nonaqueous electrolyte battery using a lithium nickel composite oxide as a positive electrode active material can exhibit an excellent charge / discharge capacity. Therefore, the nonaqueous electrolyte battery according to the embodiment can exhibit an excellent charge capacity.

  In addition, the nonaqueous electrolyte battery according to the embodiment exhibits good charge / discharge cycle characteristics for the reason described below because the particle size distribution of the positive electrode active material-containing layer obtained by the laser diffraction scattering method satisfies the above conditions. be able to.

First, in the particle size distribution, the average particle size d ₅₀ in the range of 1 μm to 5.5 μm mainly reflects the particle size of at least one lithium nickel composite oxide contained in the positive electrode active material-containing layer. Yes. The average particle size d ₅₀ is also affected by the content of the lithium nickel composite oxide in the positive electrode active material-containing layer. That is, when the content of the lithium nickel composite oxide in the positive electrode active material-containing layer is increased, the average particle diameter d ₅₀ for the positive electrode active material-containing layer is increased, and the content of the lithium nickel composite oxide is decreased. if the average particle size d ₅₀ of the positive electrode active material-containing layer is reduced.

  Further, the maximum particle size in the range of 10 μm or more and 100 μm or less in the particle size distribution is the largest particle size detected when measuring the particle size distribution of the positive electrode active material-containing layer.

Further, the particle diameter d ₁₀ in the range of 0.5 μm to 3 μm in the particle size distribution mainly reflects the particle diameter of the conductive agent having a small particle diameter among the conductive agents contained in the positive electrode active material-containing layer. It is also affected by the content.

And X which is 0.5 or more and less than 1 is represented by X = (d ₅₀ −d ₁₀ ) / d ₅₀ , and the average particle diameter d ₅₀ and the particle diameter d in the particle size distribution for the positive electrode active material-containing layer. The difference from ₁₀ is divided by the average particle size d ₅₀ . That is, X mainly reflects the conductive agent contained in the positive electrode active material-containing layer and the particle diameter of the lithium nickel composite oxide contained in the positive electrode active material-containing layer, and is also affected by the content.

  In the nonaqueous electrolyte battery according to the embodiment, since the particle size distribution satisfies the above conditions, the positive electrode active material-containing layer has a particle size sufficiently smaller than the particle size of the lithium nickel composite oxide and is sufficiently dispersed. Contains a conductive agent. Therefore, in the positive electrode active material-containing layer, the lithium nickel composite oxide is coated with a small particle conductive agent. By the presence of such a small particle conductive agent coating, side reactions of the positive electrode lithium nickel composite oxide during charging and discharging can be suppressed, and a decrease in charge and discharge capacity associated with the cycle can be suppressed.

  In the nonaqueous electrolyte battery according to the embodiment, a small conductive agent coated with a lithium nickel composite oxide can form an excellent conductive path.

  As a result, the nonaqueous electrolyte battery according to the embodiment can exhibit good charge / discharge cycle characteristics.

That the value of X for the positive electrode active material-containing layer is less than 0.5 means that the difference between the average particle diameter d ₅₀ and the particle diameter d ₁₀ in the particle size distribution is too small. The reason why the difference between the average particle diameter d ₅₀ and the particle diameter d ₁₀ in the particle size distribution is so small is considered to be the following three reasons. Charging / discharging cycle characteristics cannot be shown.

  First, it is conceivable that the difference between the particle size of the conductive agent and the particle size of the lithium nickel composite oxide is too small, that is, the particle size of the conductive agent is close to the particle size of the lithium nickel composite oxide. When the particles of the lithium nickel composite oxide are coated with conductive agent particles having the same particle diameter as this, there is a high possibility that gaps will be formed between the particles, so that sufficient coating with the conductive agent cannot be obtained. Therefore, such a nonaqueous electrolyte battery cannot suppress a side reaction of the lithium nickel composite oxide during charging and discharging. In this case, the positive electrode cannot have a good conductive path. As a result, when such a nonaqueous electrolyte battery is cycled, the charge / discharge capacity decreases.

  Next, it is conceivable that the particle diameter of the lithium nickel composite oxide is too small. The lithium nickel composite oxide has a larger surface area as the particle diameter is smaller. The lithium nickel composite oxide having a large surface area promotes side reactions with the nonaqueous solvent and the electrolyte during charging and discharging. A non-aqueous electrolyte battery including such a lithium nickel composite oxide in the positive electrode has a reduced charge / discharge capacity when repeated cycles.

  And it is thought that the quantity of the small particle | grain electrically conductive agent contained in a positive electrode active material content layer is not enough compared with the quantity of lithium nickel complex oxide. In this case, the coating of the lithium nickel composite oxide with the small particle conductive agent cannot be sufficiently obtained, and the side reaction of the lithium nickel composite oxide cannot be suppressed during charge / discharge of the nonaqueous electrolyte battery. In this case, the positive electrode active material-containing layer cannot have a good conductive path.

  Thus, the nonaqueous electrolyte battery whose X value for the positive electrode active material-containing layer is less than 0.5 cannot exhibit good charge / discharge cycle characteristics.

Note that the particle size d ₅₀ and the particle size d ₁₀ in the particle size distribution of the positive electrode active material-containing layer are both positive values, and d ₅₀ is always larger than d ₁₀ . Therefore, X for the positive electrode active material-containing layer does not take a value of 1 or more and does not take a negative value.

  If the maximum particle size in the particle size distribution of the positive electrode active material-containing layer is larger than 100 μm, it is difficult to produce a positive electrode having uniform quality. On the other hand, when the maximum particle size is smaller than 10 μm, the surface area of the lithium nickel composite oxide increases. As described above, the charge / discharge capacity of a nonaqueous electrolyte battery including a lithium nickel composite oxide having a large surface area in the positive electrode can be reduced when the cycle is repeated.

In the positive electrode active material-containing layer having a particle diameter d ₁₀ in the particle size distribution larger than 3 μm, the particle diameter of the conductive agent is too large, or the conductive agent particles are not sufficiently dispersed and aggregated in the positive electrode active material-containing layer. Conceivable. In such a non-aqueous electrolyte battery, a sufficient coating with a small particle conductive agent cannot be obtained, so that side reactions of the lithium nickel composite oxide cannot be suppressed during charging and discharging, and a good conductive path is obtained. Can't have.

On the other hand, the positive electrode active material-containing layer having a particle size distribution with a particle diameter d ₁₀ of less than 0.5 μm has a high surface area for both the conductive agent and the active material, and the side reactivity with the nonaqueous solvent and the electrolyte is increased. When charging is repeated, the charge / discharge capacity may be reduced.

In the positive electrode active material-containing layer having an average particle diameter d ₅₀ in the particle size distribution larger than 5.5 μm, the particle diameter of the lithium nickel composite oxide is too large, or the lithium nickel composite oxide particles are sufficiently dispersed in the positive electrode active material-containing layer. It is thought that it is not agglomerated. In such a non-aqueous electrolyte battery, the above effect obtained by coating the lithium nickel composite oxide with a conductive agent cannot be obtained, and a good conductive path cannot be obtained.

On the other hand, in the positive electrode active material-containing layer having an average particle diameter d ₅₀ in the particle size distribution of less than 1 μm, the lithium nickel composite oxide particles are too small and the side reactivity is increased. obtain.

Examples of the lithium nickel composite oxide included in the positive electrode active material-containing layer include a Li—Ni—Al composite oxide, a Li—Ni—Co—Mn composite oxide, and a Li—Ni—Mn composite oxide. As a preferable lithium nickel composite oxide, LiNi _7/10 Co _2/10 Mn _1/10 O ₂ which is a Li—Ni—Co—Mn composite oxide can be mentioned. The positive electrode active material can include one or more lithium nickel composite oxides.

  The content of nickel element in the positive electrode active material-containing layer is preferably in the range of 23 wt% to 45 wt%. The content of nickel element in the positive electrode active material-containing layer can be measured, for example, by inductively coupled plasma atomic spectroscopy (ICP analysis). The nonaqueous electrolyte battery according to the embodiment in which the content of nickel element in the positive electrode active material-containing layer is 23% by weight or more can exhibit a more excellent charge / discharge capacity, and the effect of improving the cycle characteristics is more remarkable. Can be shown. In addition, the nonaqueous electrolyte battery according to the embodiment in which the content of nickel element in the positive electrode active material-containing layer is 45% by weight or less suppresses substitution of nickel element and lithium element in the positive electrode active material-containing layer during charge / discharge. The structure change of the positive electrode active material-containing layer can be suppressed, and as a result, more excellent cycle characteristics can be exhibited.

  The conductive agent contained in the positive electrode active material-containing layer preferably contains a carbon material. A conductive agent containing a carbon material can provide a better conductive path.

The positive electrode active material-containing layer preferably has a density in the range of 2.4 g / cm ³ or more and 3.6 g / cm ³ or less. The nonaqueous electrolyte battery according to the embodiment in which the density of the positive electrode active material-containing layer is within this range can form a better charge / discharge path and further suppress the side reaction of the lithium nickel composite oxide. it can. Moreover, the nonaqueous electrolyte battery according to the embodiment in which the density of the positive electrode active material-containing layer is within the above range can further suppress variation in the impregnation property of the nonaqueous electrolyte in the positive electrode active material-containing layer. When the non-aqueous electrolyte impregnation in the positive electrode active material-containing layer varies, the applied voltage varies in the positive electrode active material-containing layer. In a portion where a higher potential is applied than the other portions in the positive electrode active material-containing layer, side reactions, in particular, decomposition of the nonaqueous electrolyte is promoted.

  The density of the positive electrode active material-containing layer can be calculated by measuring the weight of the positive electrode and the volume of the positive electrode, and subtracting the weight and thickness of the positive electrode current collector.

  Next, an example of a procedure for obtaining the particle size distribution of the positive electrode active material-containing layer by a laser diffraction scattering method and an example of a procedure for analyzing the content of Ni element in the positive electrode active material-containing layer by ICP will be described.

(1) An example of a procedure for obtaining the particle size distribution of the positive electrode active material-containing layer by a laser diffraction scattering method. Disassembly of the non-aqueous electrolyte battery First, as a preliminary preparation, wear gloves so as not to directly touch the electrode and the non-aqueous electrolyte.
Next, in order to prevent the battery components from reacting with atmospheric components and moisture during disassembly, the nonaqueous electrolyte battery is placed in a glove box with an argon atmosphere.
A non-aqueous electrolyte battery is opened in such a glove box. For example, the non-aqueous electrolyte battery can be opened by cutting the heat seal portion around each of the positive electrode current collecting tab and the negative electrode current collecting tab.
An electrode group is taken out from the opened nonaqueous electrolyte battery. When the extracted electrode group includes the positive electrode lead and the negative electrode lead, the positive electrode lead and the negative electrode lead are cut while being careful not to short-circuit the positive and negative electrodes.
Next, the electrode group is disassembled and decomposed into a positive electrode, a negative electrode, and a separator. The positive electrode thus obtained is washed using ethyl methyl carbonate as a solvent.
After washing, the positive electrode is subjected to vacuum drying. Or you may use for the natural drying in argon atmosphere.

2. Particle size distribution measurement The positive electrode active material-containing layer is peeled off from the dried positive electrode using, for example, a spatula.
The peeled powdered positive electrode active material-containing layer sample is put into a measurement cell filled with N-methylpyrrolidone until a measurable concentration is reached. In addition, the capacity | capacitance of a measurement cell and a measurable density | concentration differ with particle size distribution measuring apparatuses.
The measurement cell containing the N-methylpyrrolidone and the positive electrode active material-containing layer sample dissolved therein is irradiated with ultrasonic waves for 5 minutes. The output of the ultrasonic wave is set within a range of 35 W to 45 W, for example. For example, when N-methylpyrrolidone is used as a solvent in an amount of about 50 ml, an ultrasonic wave with an output of about 40 W is irradiated for 300 seconds to the solvent mixed with the measurement sample. By such ultrasonic irradiation, aggregation of the conductive agent particles and the active material particles can be solved.
The measurement cell that has been subjected to ultrasonic treatment is inserted into a particle size distribution measuring apparatus using a laser diffraction scattering method, and the particle size distribution is measured. Examples of the particle size distribution measuring apparatus include Microtrac 3100 and Microtrac 3000 II. Thus, the particle size distribution of the positive electrode active material-containing layer can be obtained.

(2) An example of a procedure for analyzing the content of Ni element in the positive electrode active material-containing layer by ICP First, the nonaqueous electrolyte battery is disassembled by the same method as that for measuring the particle size distribution, and the positive electrode is taken out.
The taken-out positive electrode is immersed in an ethyl methyl carbonate (MEC) solvent for 20 minutes. Subsequently, the MEC is replaced, and the positive electrode is immersed again in it for 20 minutes.
Remove the positive electrode from the MEC and vacuum dry the positive electrode at 80 ° C. for 1 hour.
In the following description of the procedure, a case will be described in which the number of positive electrodes used for analysis is one with an area of about 70 mm × 90 mm.
The positive electrode active material-containing layer is peeled off from the dried positive electrode with a spatula, and a positive electrode active material-containing layer sample is collected.

Next, the positive electrode active material-containing layer sample is placed in a beaker, and 20 ml of water is added to the beaker. Then, carefully add 20 ml of hydrochloric acid little by little.
Next, the beaker is heated to dissolve the positive electrode active material-containing layer sample, and is concentrated until the liquid amount becomes about half.
After concentration, cool the beaker. After cooling, add 20 ml of hydrochloric acid and 1 ml of hydrogen peroxide to a beaker.
Next, the beaker is heated again to completely dissolve the undissolved positive electrode active material-containing layer sample, and is concentrated until the liquid volume becomes about 10 ml.
Next, add water to the beaker until the liquid volume is about 50 ml, and heat until boiling.
After cooling, the liquid in the beaker is filtered using a filter paper (grade: 5 types C), and the obtained filtrate is made up to a constant volume of 200 ml using water. The solution having a constant volume in this way is designated as sample solution A.
Next, the sample solution A is diluted with water so that the Ni concentration is about 5 to 9 μg / ml. Let the solution obtained by this dilution be the sample solution B.
Meanwhile, a commercially available Ni standard solution (1000 μg / ml) is diluted to prepare standard solutions having concentrations of 0 μg / ml, 5 μg / ml and 10 μg / ml, respectively.
The luminescence intensity of the standard solution and the sample solution B is measured using an ICP emission analyzer. A calibration curve is created using the luminescence intensity for the standard solution. Using this calibration curve, the Ni concentration in the sample solution B is calculated by the calibration curve method.
From the calculated result, the Ni content in the positive electrode active material-containing layer is calculated.

  Thus, the content of Ni element in the positive electrode active material-containing layer can be analyzed by ICP.

  Next, the nonaqueous electrolyte battery according to the embodiment will be described in more detail.

  The nonaqueous electrolyte battery according to the embodiment includes a positive electrode, a negative electrode, and a nonaqueous electrolyte.

  The positive electrode includes a positive electrode current collector and a positive electrode active material-containing layer formed on the positive electrode current collector.

  The positive electrode current collector can include a portion where the positive electrode active material-containing layer is not formed on the surface, and this portion can serve as a positive electrode lead.

  As the positive electrode current collector, for example, a metal foil such as aluminum or copper can be used.

  The positive electrode active material-containing layer includes at least one lithium nickel composite oxide and a conductive agent. The positive electrode active material-containing layer can also contain an active material other than the lithium nickel composite oxide. Examples of other active materials that can be included in the positive electrode active material-containing layer include Li—Mn oxide and Li—Co oxide.

  As described above, the conductive agent included in the positive electrode active material layer preferably includes a carbon material. Examples of the carbon material include acetylene black, ketjen black, furnace black, graphite, and carbon nanotube. The positive electrode active material-containing layer can contain one or more of the above carbon materials, or can further contain another conductive agent.

  In addition, the positive electrode active material-containing layer can further contain a binder. The binder that the positive electrode active material layer can contain is not particularly limited. For example, a polymer that is well dispersed in a mixing solvent for slurry preparation can be used as the binder. Examples of such a polymer include polyvinylidene fluoride, hexafluoropropylene, and polytetrafluoroethylene.

  The positive electrode can be produced, for example, by the following method. First, at least one lithium nickel composite oxide, any other active material, a conductive agent, and any binder are charged into a suitable solvent to obtain a mixture. Subsequently, the obtained mixture is put into a stirrer. In this stirrer, the mixture is stirred to obtain a slurry. The positive electrode can be produced by applying the slurry thus obtained onto the positive electrode current collector, drying the slurry, and then pressing the slurry. The particle size distribution of the positive electrode active material-containing layer can be adjusted to the conditions described above, for example, by adjusting the conditions for stirring the mixture, the particle diameter of the lithium nickel composite oxide, and the like.

  The aggregation level between the lithium nickel composite oxide particles and the aggregation level between the conductive agent particles in the slurry obtained as described above are the particle size distribution of the positive electrode active material-containing layer obtained by the method described above. It is reflected in.

  The negative electrode can include a negative electrode current collector and a negative electrode active material-containing layer formed on the negative electrode current collector. The negative electrode current collector can include a portion where the negative electrode active material-containing layer is not formed on the surface, and this portion can serve as a negative electrode lead.

  As the negative electrode current collector, for example, a metal foil such as aluminum or copper can be used.

  The negative electrode active material-containing layer can include, for example, a negative electrode active material, a conductive agent, and a binder.

  The negative electrode active material that can be included in the negative electrode active material-containing layer is not particularly limited. For example, as the negative electrode active material, graphite material or carbonaceous material (for example, graphite, coke, carbon fiber, spherical carbon, pyrolytic gas phase carbonaceous material, resin fired body, etc.), chalcogen compound (for example, titanium disulfide, Molybdenum disulfide, niobium selenide, etc.), light metals (eg, aluminum, aluminum alloy, magnesium alloy, lithium, lithium alloy, etc.), lithium titanium oxide (eg, spinel type lithium titanate), and the like.

  The conductive agent and the binder that can be included in the negative electrode active material-containing layer can be the same as those that can be included in the positive electrode active material-containing layer.

  The negative electrode can be produced, for example, by the following procedure. First, a negative electrode active material, a conductive agent, and a binder are mixed. The mixture thus obtained is added to a solvent to prepare a slurry. This slurry is applied to the negative electrode current collector, dried, and then pressed. Thus, a negative electrode can be produced. The density of the negative electrode active material-containing layer can be measured in the same manner as the density of the positive electrode active material-containing layer.

  The positive electrode and the negative electrode can be formed such that the positive electrode active material-containing layer and the negative electrode active material-containing layer face each other with a separator interposed therebetween. The separator is not particularly limited, and for example, a microporous film, a woven fabric, a non-woven fabric, a laminate of the same material or different materials among these can be used. Examples of the material for forming the separator include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene copolymer, and cellulose.

  The structure of the electrode group formed in this way is not particularly limited. For example, the electrode body can have a stack structure. The stack structure has a structure in which the positive electrode and the negative electrode described above are stacked with a separator interposed therebetween. Alternatively, the electrode group may have a wound structure. The wound structure is a structure in which the positive electrode and the negative electrode described above are stacked with a separator interposed therebetween, and the stacked body thus obtained is wound in a spiral shape.

  The nonaqueous electrolyte can be impregnated in the electrode group, for example.

  The non-aqueous electrolyte can be prepared by dissolving an electrolyte (for example, a lithium salt) in a non-aqueous solvent.

  Examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), γ-butyrolactone (γ -BL), sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran and the like. Nonaqueous solvents may be used alone or in combination of two or more.

Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroarsenide (LiAsF ₆ ), and trifluoromethanesulfonic acid. A lithium salt such as lithium (LiCF ₃ SO ₃ ) can be given. The electrolyte may be used alone or in combination of two or more.

  The amount of electrolyte dissolved in the non-aqueous solvent is preferably 0.5 mol / L to 3 mol / L. If the electrolyte concentration is too low, sufficient ionic conductivity may not be obtained. On the other hand, if it is too high, it may not completely dissolve in the electrolyte.

  The nonaqueous electrolyte battery according to the embodiment may further include a container for housing the electrode group and the nonaqueous electrolyte.

  As the container, for example, aluminum, aluminum alloy, iron (Fe), aluminum-containing laminate film, nickel (Ni) plated iron, stainless steel (SUS), or the like can be used.

  In addition, the non-aqueous electrolyte battery according to the embodiment may further include a positive electrode current collecting tab electrically connected to the positive electrode lead and a negative electrode current collecting tab electrically connected to the negative electrode lead. . The positive electrode current collecting tab and the negative electrode current collecting tab can be pulled out of the container and serve as a positive electrode terminal and a negative electrode terminal. Or a positive electrode current collection tab and a negative electrode current collection tab can also be connected to each of a positive electrode terminal and a negative electrode terminal.

  The positive electrode current collecting tab, the negative electrode current collecting tab, the positive electrode terminal, and the negative electrode terminal are preferably formed from, for example, aluminum or an aluminum alloy.

  Next, an example of the nonaqueous electrolyte battery according to the embodiment will be described in more detail with reference to FIGS.

  FIG. 1 is a schematic cutaway perspective view of an example nonaqueous electrolyte battery according to an embodiment. FIG. 2 is a schematic cross-sectional view of a part A shown in FIG. FIG. 3 is a schematic plan view of a positive electrode included in an example nonaqueous electrolyte battery according to the embodiment.

  A non-aqueous electrolyte battery 1 of the first example shown in FIGS. 1 to 3 includes an electrode group 2 shown in FIGS. 1 and 2, a container 3 shown in FIGS. 1 and 2, and a positive electrode shown in FIGS. A current collecting tab 4 and a negative electrode current collecting tab 5 shown in FIG. 1 are provided.

  The electrode group 2 shown in FIGS. 1 and 2 includes a plurality of positive electrodes 6, a plurality of negative electrodes 7, and a single separator 8.

  As shown in FIGS. 2 and 3, the positive electrode 6 includes a positive electrode current collector 61 and a positive electrode active material-containing layer 62 formed on both surfaces of the positive electrode current collector 61. As shown in FIGS. 2 and 3, the positive electrode current collector 61 includes a portion 63 on the surface where the positive electrode active material-containing layer 62 is not formed, and this portion 63 serves as a positive electrode lead. As shown in FIG. 3, the positive electrode lead 63 is a narrow portion that is narrower than the positive electrode active material-containing layer 62.

  As shown in FIG. 2, the negative electrode 7 includes a negative electrode current collector 71 and negative electrode active material-containing layers 72 formed on both surfaces of the negative electrode current collector 71. Although not shown, the negative electrode current collector 71 includes a portion where the negative electrode active material-containing layer 72 is not formed on the surface, and this portion serves as a negative electrode lead.

  As shown in FIG. 2, the separator 8 has ninety nine folds. The positive electrode 6 or the negative electrode 7 is arranged in the space defined by the mutually facing surfaces of the separator 8 that is folded into ninety-nine folds. Thereby, as shown in FIG. 2, the positive electrode 6 and the negative electrode 7 are laminated so that the positive electrode active material-containing layer 62 and the negative electrode active material-containing layer 72 are opposed to each other with the separator 8 interposed therebetween. Thus, the electrode group 2 is formed.

  The positive electrode lead 63 of the electrode group 2 extends from the electrode group 2 as shown in FIG. As shown in FIG. 2, these positive electrode leads 63 are combined into one and connected to the positive electrode current collecting tab 4. Although not shown, the negative electrode lead of the electrode group 2 also extends from the electrode group 2. Although not shown, these negative electrode leads are combined into one and connected to the negative electrode current collecting tab 5 shown in FIG.

  Such an electrode group 2 is accommodated in a container 3 as shown in FIGS. 1 and 2.

  The container 3 is formed of an aluminum-containing laminate film composed of an aluminum foil 31 and resin films 32 and 33 formed on both surfaces thereof. The aluminum-containing laminate film forming the container 3 accommodates the electrode group 2 by being bent so that the resin film 32 faces inward with the bent portion 3d as a fold. Moreover, as shown in FIG.1 and FIG.2, the container 3 has inserted | pinched the positive electrode current collection tab 4 in the peripheral part 3b. Similarly, the container 3 sandwiches the negative electrode current collecting tab 5 at the peripheral edge 3c. Accordingly, the positive electrode current collecting tab 4 and the negative electrode current collecting tab 5 extend from the container 3 in directions opposite to each other.

  In the container 3, its peripheral portions 3 a, 3 b, and 3 c except for a portion sandwiching the positive electrode current collecting tab 4 and the negative electrode current collecting tab 5 are heat sealed by heat-sealing resin films 32 facing each other.

  In the nonaqueous electrolyte battery 1, in order to improve the bonding strength between the positive electrode current collector tab 4 and the resin film 32, an insulating film is provided between the positive electrode current collector tab 4 and the resin film 32 as shown in FIG. 2. 9 is provided. Further, at the peripheral edge 3b, the positive electrode current collecting tab 4 and the insulating film 9 are heat-sealed by thermal fusion, and the resin film 32 and the insulating film 9 are heat-sealed by thermal fusion. Similarly, although not shown, an insulating film 9 is also provided between the negative electrode current collecting tab 5 and the resin film 32. Further, at the peripheral edge portion 3c, the negative electrode current collecting tab 5 and the insulating film 9 are heat sealed by heat fusion, and the resin film 32 and the insulating film 9 are heat sealed by heat fusion. That is, in the nonaqueous electrolyte battery 1 shown in FIGS. 1 to 3, all the peripheral portions 3 a, 3 b and 3 c of the container 3 are heat-sealed.

  The container 3 further stores a nonaqueous electrolyte (not shown). The nonaqueous electrolyte is impregnated in the electrode group 2.

  In the nonaqueous electrolyte battery 1 shown in FIGS. 1 to 3, a plurality of positive electrode leads 63 are collected in the lowermost layer of the electrode group 2 as shown in FIG. 2. Similarly, although not shown, a plurality of negative electrode leads are collected in the lowermost layer of the electrode group 2. However, as shown in FIG. 4, for example, a plurality of positive electrode leads 63 and a plurality of negative electrode leads 73 are combined in the vicinity of the middle stage of the electrode group 2, and each of the positive electrode current collecting tab 4 and the negative electrode current collecting tab 5 is combined. Can be connected to.

  According to the embodiment described above, a nonaqueous electrolyte battery is provided. The particle size distribution of the positive electrode active material-containing layer containing at least one lithium nickel composite oxide and a conductive agent of the nonaqueous electrolyte battery satisfies the conditions described above. Thanks to this, the nonaqueous electrolyte battery according to the embodiment can exhibit good charge / discharge cycle characteristics.

(Example)
Examples will be described below.

[Example 1]
In Example 1, the nonaqueous electrolyte battery 1 shown in FIGS. 1 to 3 was produced by the following procedure.

[Preparation of Positive Electrode 6]
LiNi _7/10 Co _2/10 Mn _1/10 O ₂ having an average particle diameter of 6 μm was used as the positive electrode active material. This active material, acetylene black, graphite, and polyvinylidene fluoride were mixed at a ratio of 100: 8: 5: 3 by the following procedure. First, an active material, acetylene black, and graphite were dry-mixed using a Henschel mixer. After dry mixing, polyvinylidene fluoride and N-methyl-2-pyrrolidone were added to the obtained dry mixture and wet-mixed with a planetary mixer. In this way, a mixture containing each material at the above ratio was prepared.

  Subsequently, the prepared mixture was charged into a THINKY Smelting Taro (ARE-250), which is a rotation / revolution mixer, and stirred at a rotation speed of 2000 rpm for 30 minutes. Subsequently, the mixture was transferred from Ryotaro to an imex 4-cylinder sand grinder as a disperser, filled with glass beads having a diameter of 0.7 to 1.0 mm, and further stirred for 30 minutes at a rotation speed of 2000 rpm.

The positive electrode slurry obtained after stirring was applied to both surfaces of an aluminum foil 61 having a thickness of 20 μm with a coating apparatus so that the coating amount per unit area was 110 g / m ² . At this time, a portion 63 where the slurry was not applied was left on the aluminum foil 61. The obtained coating film was dried, and then rolled with a roll press so that the electrode density (density of the positive electrode active material-containing layer 62) was 2.6 g / cm ³ . Finally, the portion 63 where the slurry was not applied was punched out to form a narrow portion 63 as a positive electrode lead shown in FIG. Thus, a plurality of positive electrodes 6 were produced.

[Preparation of negative electrode 7]
Lithium titanate Li ₄ Ti ₅ O ₁₂ was used as the negative electrode active material. This active material, graphite, and polyvinylidene fluoride were mixed at a ratio of 100: 9: 4. Subsequently, this mixture was kneaded using N-methyl-2-pyrrolidone as a solvent to obtain a mixture. Subsequently, the mixture was stirred to prepare a negative electrode slurry. The obtained negative electrode slurry was applied to an aluminum foil 71 having a thickness of 12 μm with a coating apparatus so that the coating amount per unit area was 110 g / m ² . At this time, a portion where the slurry was not applied was left on the aluminum foil 71. The obtained coating film was dried, and then rolled with a roll press so that the electrode density (density of the negative electrode active material-containing layer 72) was 2.4 g / cm ³ . As with the positive electrode 6, the portion where the slurry was not applied was punched out to form a narrow portion as a negative electrode lead similar to the positive electrode 6 shown in FIG. 3. Thus, a plurality of negative electrodes 7 were produced.

[Production of electrode group 2]
A strip-shaped microporous membrane separator 8 having a thickness of 30 μm was prepared. The separator 8 was made into ninety-nine folds, and the positive electrode 6, the negative electrode 7, and the separator 8 were laminated as described with reference to FIG. At this time, the plurality of positive electrode leads 63 and the plurality of negative electrode leads were extended in opposite directions from the laminated body. Finally, a winding tape (not shown) was applied to the obtained laminate to form an electrode group 2.

[Connection of Positive Current Collection Tab 4 and Negative Current Collection Tab 5 to Electrode 2]
The positive electrode current collection tab 4 and the negative electrode current collection tab 5 were produced using aluminum. Subsequently, the positive leads 63 of the plurality of positive electrodes 6 were combined and connected to the positive electrode current collecting tab 4. Similarly, the negative electrode leads of the plurality of negative electrodes 7 were combined into one and connected to the negative electrode current collecting tab 5. In this way, the positive electrode current collecting tab 4 and the negative electrode current collecting tab 5 are installed so as to extend in the opposite directions from the electrode group 2 so that current collection from the positive electrode 6 and the negative electrode 7 can be easily performed. did.

[Preparation of container 3]
An aluminum-containing laminate film was used as the container 3. First, the aluminum-containing laminate film 3 was molded into a shape that can accommodate the electrode group 2. The electrode group 2 was housed in the aluminum-containing laminate film 3 thus formed as described above with reference to FIGS. 1 and 2. At this time, as shown in FIG. 2, the positive electrode current collecting tab 4 was sandwiched by the resin film 32 at the peripheral edge 3 b of the container 3. Similarly, although not shown in FIG. 2, the negative electrode current collecting tab 5 is sandwiched between the resin film 32 at the peripheral edge 3 c of the container 3. The insulating film 9 was disposed between the positive electrode current collecting tab 4 and the resin film 32 and between the negative electrode current collecting tab 5 and the resin film 32.

  Subsequently, the resin film 32 opposed at the peripheral edge portions 3a, 3b and 3c was fixed by heat fusion, leaving a part. At the same time, at the peripheral edge 3b, the resin film 32 and the insulating film 9 opposed thereto are thermally fused and fixed, and the positive electrode current collecting tab 4 and the insulating film 9 opposed thereto are thermally fused and fixed. did. Similarly, at the peripheral edge portion 3c, the resin film 32 and the insulating film 9 facing the resin film 32 are fixed by thermal fusion, and the negative electrode current collecting tab 5 and the insulating film 9 opposed thereto are thermally fused. Fixed. Thus, a cell before injection was prepared.

[Nonaqueous electrolyte injection]
The non-aqueous electrolyte used was a mixture of ethylene carbonate and dimethyl carbonate 1: 1 as the non-aqueous solvent, and 2 mol / l lithium hexafluorophosphate as the electrolyte. This non-aqueous electrolyte was injected into the pre-injection cell described above. The non-aqueous electrolyte was injected through the portion of the peripheral portion of the container 3 that was left without being thermally fused.

[Preparation of Nonaqueous Electrolyte Battery 1]
Finally, the portion of the peripheral portion of the container 3 that was left without being heat-sealed was heat-sealed to produce the nonaqueous electrolyte battery 1.

[Evaluation]
The charge / discharge cycle characteristics and particle size distribution of the positive electrode active material-containing layer 62 of the nonaqueous electrolyte battery 1 of Example 1 produced in this manner were measured by the following procedure.

(Charge / discharge cycle characteristics)
The nonaqueous electrolyte battery 1 of Example 1 was repeatedly charged and discharged 300 times in an environment of 60 ° C. At this time, both charging and discharging were performed at a current value of 2C. The capacity at the first cycle (one charge / discharge) and the capacity at the 300th cycle were measured.

  A value obtained by dividing the capacity at the 300th cycle thus obtained by the capacity at the first cycle was defined as a capacity retention ratio after 300 cycles.

  The capacity retention rate after 300 cycles of the nonaqueous electrolyte battery 1 of Example 1 was 90%.

(Measurement of particle size distribution of positive electrode active material-containing layer 62)
For the nonaqueous electrolyte battery 1 of Example 1, the particle size distribution was measured using the laser diffraction scattering type particle diameter and particle size distribution measuring apparatus using the method described above. The obtained particle size distribution is shown by a solid line in FIG.

In the particle size distribution of the positive electrode active material-containing layer 62 of the nonaqueous electrolyte battery 1 of Example 1, the average particle size d ₅₀ is 3.7 μm, the particle size d ₁₀ is 1.00 μm, and the maximum particle size is 14. The value of X represented by X = (d ₅₀ −d ₁₀ ) / d ₅₀ was 0.73.

[Example 2]
In Example 2, the nonaqueous electrolyte battery 1 was produced in the same procedure as in Example 1 except that the rotational speed of the sand grinder was 1000 rpm.

  For the nonaqueous electrolyte battery 1 of Example 2, the charge / discharge cycle characteristics and the particle size distribution were evaluated in the same manner as in Example 1.

The capacity retention rate after 300 cycles of the nonaqueous electrolyte battery 1 of Example 2 was 85%. In the particle size distribution for the nonaqueous electrolyte battery 1 of Example 2, the average particle size d ₅₀ is 3.9 μm, the particle size d ₁₀ is 1.37 μm, and the maximum particle size is 15.4 μm. The value of X was 0.65.

[Example 3]
In Example 3, the nonaqueous electrolyte battery 1 was prepared in the same procedure as in Example 1 except that LiNi _7/10 Co _2/10 Mn _1/10 O ₂ having an average particle diameter of 5 μm was used as the positive electrode active material. Was made.

  For the nonaqueous electrolyte battery 1 of Example 3, the charge / discharge cycle characteristics and the particle size distribution were evaluated in the same manner as in Example 1.

The capacity retention rate after 300 cycles of the nonaqueous electrolyte battery 1 of Example 3 was 94%. In the particle size distribution of the nonaqueous electrolyte battery 1 of Example 3, the average particle size d ₅₀ is 3.0 μm, the particle size d ₁₀ is 0.90 μm, and the maximum particle size is 13.1 μm. The value of X was 0.70.

[Example 4]
In Example 4, except that LiNi _7/10 Co _2/10 Mn _1/10 O ₂ having an average particle diameter of 5 μm was used as the positive electrode active material, and the rotational speed of the sand grinder was 1000 rpm, A non-aqueous electrolyte battery 1 was produced in the same procedure as in Example 1.

  For the nonaqueous electrolyte battery 1 of Example 4, the charge / discharge cycle characteristics and the particle size distribution were evaluated in the same manner as in Example 1.

The capacity retention rate after 300 cycles of the nonaqueous electrolyte battery 1 of Example 4 was 89%. Further, in the particle size distribution for the nonaqueous electrolyte battery 1 of Example 4, the average particle diameter d ₅₀ is 3.6 μm, the particle diameter d ₁₀ is 1.51 μm, and the maximum particle diameter is 15.6 μm. The value of X was 0.58.

[Comparative Example 1]
In Comparative Example 1, a nonaqueous electrolyte battery was produced in the same procedure as in Example 1 except that the stirring of the slurry by the sand grinder was omitted.

  For the nonaqueous electrolyte battery of Comparative Example 1, the charge / discharge cycle characteristics and the particle size distribution were evaluated in the same manner as in Example 1.

  The particle size distribution obtained for the nonaqueous electrolyte battery 1 of Comparative Example 1 is shown by a broken line in FIG.

The capacity retention rate after 300 cycles of the nonaqueous electrolyte battery of Comparative Example 1 was 58%. In the particle size distribution of the nonaqueous electrolyte battery of Comparative Example 1, the average particle diameter d ₅₀ is 4.5 μm, the particle diameter d ₁₀ is 2.97 μm, the maximum particle diameter is 14.3 μm, The value of was 0.34.

[Comparative Example 2]
In Comparative Example 2, a nonaqueous electrolyte battery was prepared in the same procedure as in Example 1 except that LiNi _7/10 Co _2/10 Mn _1/10 O ₂ having an average particle diameter of 10 μm was used as the positive electrode active material. Produced.

  For the nonaqueous electrolyte battery of Comparative Example 2, the charge / discharge cycle characteristics and the particle size distribution were evaluated in the same manner as in Example 1.

The capacity retention rate after 300 cycles of the nonaqueous electrolyte battery of Comparative Example 2 was 70%. In the particle size distribution of the nonaqueous electrolyte battery of Comparative Example 2, the average particle diameter d ₅₀ is 7.0 μm, the particle diameter d ₁₀ is 1.54 μm, the maximum particle diameter is 13.8 μm, and X The value of was 0.78.

The results of Examples 1 to 4 and Comparative Examples 1 and 2 are summarized in Tables 1 and 2 below.

[result]
As shown in Tables 1 and 2, the non-aqueous electrolyte batteries 1 of Examples 1 to 4 exhibited a capacity retention rate superior after 300 cycles as compared with the non-aqueous electrolyte batteries of Comparative Examples 1 and 2. . This is because the positive electrode active material-containing layer 62 of the nonaqueous electrolyte battery 1 of Examples 1 to 4 has an average particle diameter d _{50 in} the range of 1 μm to 5.5 μm in the particle size distribution obtained by the laser diffraction scattering method. Yes, the maximum particle diameter is in the range of 10 μm to 100 μm, the particle diameter d ₁₀ is in the range of 0.5 μm to 3 μm, and X = (d ₅₀ −d ₁₀ ) / d ₅₀ Was within the range of 0.5 or more and less than 1, because the aggregation of the small-particle conductive agent was small, and the particles of the lithium nickel composite oxide as the positive electrode active material were coated with the small-particle conductive agent. This is because the side reaction accompanying the charge / discharge cycle can be suppressed and an excellent conductive path can be provided.

In particular, the nonaqueous electrolyte battery 1 of Example 3 exhibited cycle characteristics superior to those of Examples 1, 2, and 4. This is because the effect that the conductive agent coats the particles of the lithium nickel composite oxide can be obtained more significantly by making the average particle diameter d ₅₀ in the particle size distribution of the positive electrode active material-containing layer 62 smaller, and the side reaction can be further increased. It was because it was able to be suppressed.

  In addition, from the result of the particle size distribution of Example 1 and Example 2, it was found that when the rotational speed of the sand grinder was decreased, the average particle size was increased and the X value was decreased. Moreover, it turned out from the particle size distribution of Example 3 and Example 4 that the value of X becomes small when the rotation speed of the stirrer is lowered. Nevertheless, since the nonaqueous electrolyte battery 1 of Examples 2 and 4 had an X value of 0.5 or more and less than 1, it was possible to show excellent cycle characteristics.

  On the other hand, the nonaqueous electrolyte batteries of Comparative Examples 1 and 2 were inferior in capacity retention rate after 300 cycles as compared with the nonaqueous electrolyte batteries of Examples 1 to 4.

  In particular, the non-aqueous electrolyte battery of Comparative Example 1 in which the value of X was 0.34 was extremely inferior to Examples 1 to 4 in capacity retention after 300 cycles. This is presumably because, in Comparative Example 1, since the stirring step was omitted, the conductive agent particles aggregated non-uniformly. In FIG. 5, the particle size distribution of Example 1 indicated by a solid line has a gentle and broad peak extending in a small particle diameter region, whereas the particle size distribution of Comparative Example 1 indicated by a broken line is a small particle. It can be seen from the absence of such a broad peak in the radial region. As described above, in the nonaqueous electrolyte battery of Comparative Example 1, the conductive agent particles aggregated non-uniformly, so that the effect of coating the lithium nickel composite oxide particles cannot be obtained and deteriorated due to a side reaction accompanying the charge / discharge cycle. As a result, it is considered that the cycle characteristics were extremely inferior to those of the nonaqueous electrolyte batteries 1 of Examples 1 to 4.

In the nonaqueous electrolyte battery of Comparative Example 2, the value of X was 0.78, but the average particle size d ₅₀ of the particle size distribution of the positive electrode active material-containing layer 62 was 7.0 μm, which was 5.5 μm. It was bigger than. This is considered that in the nonaqueous electrolyte battery of Comparative Example 2, the lithium nickel composite oxide particles were not sufficiently dispersed and aggregated. Therefore, the nonaqueous electrolyte battery of Comparative Example 2 was deteriorated due to side reactions accompanying the charge / discharge cycle, and as a result, it was considered that the cycle characteristics were inferior to the nonaqueous electrolyte battery 1 of Examples 1 to 4. It is done.

  In the above examples, Rentaro (ARE-250) was used. However, the positive electrode having the particle size distribution described in the embodiment can be manufactured even if a mixer having equivalent performance is used instead of Rintaro.

That is, in the nonaqueous electrolyte battery according to at least one embodiment and example described above, X represented by X = (d ₅₀ −d ₁₀ ) / d _{50 is} in the range of 0.5 or more and less than 1. For this reason, at least one lithium nickel composite oxide is coated with a small particle conductive agent. Thanks to this, the nonaqueous electrolyte battery according to the embodiment can exhibit good charge / discharge cycle characteristics.

Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.
The invention described in the claims at the beginning of the filing of the present application will be appended.
[1] A positive electrode comprising a positive electrode current collector and a positive electrode active material-containing layer formed on the positive electrode current collector, wherein the positive electrode active material-containing layer contains at least one lithium nickel composite oxide and a conductive agent The positive electrode active material-containing layer has a mean particle diameter d _{50 in} the range of 1 μm or more and 5.5 μm or less in a particle size distribution obtained by a laser diffraction scattering method, and a negative electrode and a non-aqueous electrolyte. The maximum particle diameter is in the range of 10 μm to 100 μm, the particle diameter d _{10 at} which the cumulative frequency from the small particle diameter side is 10% is in the range of 0.5 μm to 3 μm, and X = (d ₅₀ − A non-aqueous electrolyte battery characterized in that X represented by d ₁₀ ) / d _{50 is} in a range of 0.5 or more and less than 1.
[2] The nonaqueous electrolyte battery according to [1], wherein the content of nickel element in the positive electrode active material-containing layer is in the range of 23 wt% to 45 wt%.
[3] The nonaqueous electrolyte battery according to [2], wherein the conductive agent includes a carbon material.
[4] The nonaqueous electrolyte battery according to [2], wherein the density of the positive electrode active material-containing layer is in a range of 2.4 g / cm ^{3 to} 3.6 g / cm ³ .

  DESCRIPTION OF SYMBOLS 1 ... Non-aqueous electrolyte battery, 2 ... Electrode group, 3 ... Container, 3a, 3b and 3c ... Periphery part of container, 3d ... Bending part of container, 31 ... Aluminum foil, 32 and 33 ... Resin film, 4 ... Positive electrode collection Electrical tab, 5 ... Negative current collector tab, 6 ... Positive electrode, 61 ... Positive current collector, 62 ... Positive electrode active material-containing layer, 63 ... Positive electrode lead, 7 ... Negative electrode, 71 ... Negative current collector, 72 ... Negative electrode active material Containing layer, 73 ... negative electrode lead, 8 ... separator, 9, insulating film.

Claims (7)

A positive electrode current collector and a positive electrode active material-containing layer formed on the positive electrode current collector;
The positive electrode active material-containing layer contains at least one lithium nickel composite oxide and a conductive agent, and the particle size of the conductive agent is smaller than the average particle size of the at least one lithium nickel composite oxide,
The positive electrode active material-containing layer has an average particle diameter d _{50 in} the range of 1 μm to 5.5 μm and a maximum particle diameter in the range of 10 μm to 100 μm in the particle size distribution obtained by the laser diffraction scattering method. The particle diameter d _{10 at} which the cumulative frequency from the small particle diameter side is 10% is in the range of 0.5 μm to 3 μm, and X represented by X = (d ₅₀ −d ₁₀ ) / d ₅₀ is 0. A positive electrode in the range of 5 or more and less than 1.   The positive electrode according to claim 1, wherein the content of nickel element in the positive electrode active material-containing layer is in the range of 23 wt% or more and 45 wt% or less.   The positive electrode according to claim 1, wherein the conductive agent includes a carbon material.   The positive electrode according to claim 3, wherein the carbon material is at least one selected from the group consisting of acetylene black, ketjen black, furnace black, graphite, and carbon nanotubes.   The lithium nickel composite oxide includes at least one selected from the group consisting of a Li-Ni-Al composite oxide, a Li-Ni-Co-Mn composite oxide, and a Li-Ni-Mn composite oxide. The positive electrode of any one of 1-4. The positive electrode according to claim 1, wherein the density of the positive electrode active material-containing layer is in a range of 2.4 g / cm ³ or more and 3.6 g / cm ³ or less. The positive electrode active material-containing layer further includes a binder,
The positive electrode according to claim 1, wherein the binder includes at least one selected from the group consisting of polyvinylidene fluoride, hexafluoropropylene, and polytetrafluoroethylene.