Nonaqueous electrolyte battery and battery pack

Abstract

According to an embodiment, provided is a non-aqueous electrolyte battery comprising a positive electrode, a negative electrode, a separator provided between the positive electrode and the negative electrode, and a non-aqueous electrolyte. The positive electrode contains a single particle of a positive electrode active material represented by formula (1) and includes a positive electrode active material-containing layer having a first porosity of 10-25%. The non-aqueous electrolyte contains LiPF6 and propylene carbonate. The mass ratio of LiPF6 to propylene carbonate is 0.5-1.0. The ratio of a second porosity of the separator to the first porosity is 2.2-2.8. Formula (1): LiaNi(1-b-c-d)CobMncMdO2 Here, 1≤a≤1.2, 0≤b≤0.4, 0≤c≤0.4, 0≤d≤0.1, and M is at least one element selected from the group consisting of Fe, Cu, Ti, Mg, Al, W, Y, B, Mo, Nb, Zn, Sn, Zr, Ga, and V.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a non-aqueous electrolyte battery and a battery pack. [Background technology]

[0002] In recent years, with the spread of electric vehicles (EVs) and electric buses (EV buses), there is a need to increase the driving distance per charge. For the lithium-ion batteries that power these vehicles, there is a strong demand for high energy density lithium-ion batteries from the perspective of increasing the charging capacity per pack and reducing weight. One way to increase this energy density is to increase the battery capacity. To increase the capacity of batteries, LNCM (lithium, nickel, manganese, cobalt) composite oxides, which have a large capacity per unit mass, are promising as positive electrode active materials.

[0003] When this LNCM cathode active material is used to increase the capacity of a battery, if it is used at a high cathode potential of 4.2 V or higher, which is the potential at which a large capacity can be extracted, a significant increase in resistance occurs due to gas generation caused by a side reaction between the surface of the cathode active material particles and the electrolyte, which results in significant deterioration of the cathode during charge / discharge cycles and storage.

[0004] Increasing the positive electrode density is one way to suppress side reactions between the surface of positive electrode active material particles and the electrolyte. However, conventional LNCM positive electrode active materials are generally polycrystalline, consisting of secondary particles formed by the aggregation of fine primary particles. When these active materials are packed into the positive electrode mixture layer, they create many voids. This makes it difficult to increase the positive electrode density.

[0005] Although it is possible to increase the density of the positive electrode by applying a large press load to the positive electrode composite layer during fabrication, this not only reduces the electrolyte impregnation into the positive electrode, but also leads to problems such as a lack of electrolyte supporting salt in the voids in the positive electrode, which can lead to reduced discharge performance and uneven reaction. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-153014 [Patent Document 2] Patent Publication No. 2021-52006 [Patent Document 3] International Publication No. WO 2022 / 138451 Summary of the Invention [Problem to be solved by the invention]

[0007] A non-aqueous electrolyte battery and a battery pack are provided in which gas generation and resistance increase during cycles at high potential are suppressed. [Means for solving the problem]

[0008] According to an embodiment, a nonaqueous electrolyte battery is provided, comprising a positive electrode, a negative electrode, a separator between the positive electrode and the negative electrode, and a nonaqueous electrolyte. The positive electrode includes a positive electrode active material-containing layer containing single particles of a positive electrode active material represented by the following formula (1) and having a first porosity of 10% to 25%. The nonaqueous electrolyte includes LiPF6 and propylene carbonate. The mass ratio of LiPF6 to propylene carbonate is 0.5 to 1.0. The ratio of the second porosity of the separator to the first porosity is 2.2 to 2.8. Li a Ni (1-b-c-d) Co b Mn c M d O2(1) where 1≦a≦1.2, 0 < b ≤ 0.4, 0 < c≦0.4, 0≦d≦0.1, and M is one or more elements selected from the group consisting of Fe, Cu, Ti, Mg, Al, W, Y, B, Mo, Nb, Zn, Sn, Zr, Ga, and V.

[0009] According to another embodiment, a battery pack is provided, which includes a nonaqueous electrolyte battery according to the embodiment. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is an exploded perspective view of an example of a nonaqueous electrolyte battery according to an embodiment. [Figure 2] FIG. 2 is a partially exploded perspective view of an example of an electrode group used in the nonaqueous electrolyte battery shown in FIG. [Figure 3] FIG. 3 is a block diagram showing an example of an electric circuit of the battery pack according to the embodiment. Embodiment

[0011] (First embodiment) According to a first embodiment, a non-aqueous electrolyte battery is provided. The non-aqueous electrolyte battery includes a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte.

[0012] The positive electrode includes a positive electrode active material-containing layer. The positive electrode active material-containing layer contains, as a positive electrode active material, single particles of a lithium-containing metal oxide represented by the following formula (1). The positive electrode active material-containing layer has a first porosity of 10% or more and 25% or less. Li a Ni (1-b-c-d) Co b Mn c M d O2(1) Here, 1≦a≦1.2, 0≦b≦0.4, 0≦c≦0.4, 0≦d≦0.1, and M is one or more elements selected from the group consisting of Fe, Cu, Ti, Mg, Al, W, Y, B, Mo, Nb, Zn, Sn, Zr, Ga, and V.

[0013] The lithium-containing metal oxide represented by the formula (1) has a large capacity per unit mass and a voltage of 4.2V (vs. Li / Li + A large capacity can be obtained by using the positive electrode up to a potential of 1.05 or more. The molar ratio a in formula (1) can vary depending on the absorption and desorption of lithium ions in the positive electrode. A more preferable range is 1.05≦a≦1.15.

[0014] By setting the molar ratio b in formula (1) to 0 < b ≤ 0.4 and the molar ratio c to 0 < c ≤ 0.4, the lithium-containing metal oxide further contains Co and Mn in addition to Ni as a transition metal, so the capacity per unit mass increases. A more preferable range of the molar ratio b and the molar ratio c is 0.05 ≤ b ≤ 0.2 and 0.05 ≤ c ≤ 0.2.

[0015] A more preferable range of the molar ratio d of the element M in formula (1) is 0.01 ≤ d ≤ 0.05. By containing the element M, for example, the following advantages can be obtained. When M = Al, the lattice strain decreases and the Li-ion diffusivity improves. When M = Mg, the bulk electron conductivity improves and the apparent discharge capacity improves. Furthermore, the cycle stability under high voltage improves. When M = Zr, the cycle performance improves. When M = Ti, the cycle performance improves due to the mitigation of the phase change under high voltage charge and discharge. When M = Ga, the bulk electron conductivity improves and the cycle performance improves.

[0016] The single particle of the active material represented by formula (1) does not contain grain boundaries inside. Therefore, the specific surface area of the single particle is small, and cracking due to the expansion and contraction of the particle is difficult to occur.

[0017] The reason for setting the first porosity of the positive electrode active material-containing layer in the range of 10% or more and 25% or less will be explained. In order to prevent the depletion of the liquid due to the reaction consumption of the active material and the electrolyte, it is desirable to ensure a porosity of about 30%. However, when the porosity of the positive electrode containing the above single particles exceeds 25%, the positive electrode density is low and sufficient contact between particles cannot be ensured, so the resistance increase becomes large. In addition, due to the expansion and contraction of the positive electrode active material-containing layer accompanying the charge and discharge cycle of the battery, the area of the side reaction between the active material-containing layer and the electrolyte is likely to increase, and the gas generation amount increases. On the other hand, when the first porosity is less than 10%, the liquid absorption property of the positive electrode with respect to the electrolyte decreases, so the resistance increase becomes large.

[0018] The separator is disposed between the positive electrode and the negative electrode. The separator has a second porosity of 2.2 to 2.8 relative to the first porosity of the positive electrode active material-containing layer. That is, the separator can be formed, for example, from a porous material. A high porosity of the separator generally improves the liquid retention capacity, but if the second porosity of the separator is too high relative to the first porosity of the positive electrode, the supply of electrolyte to the positive electrode is poor. As a result, the resistance increases significantly. On the other hand, if the second porosity of the separator is too low compared to the first porosity, the electrolyte in the separator will dry up. Therefore, in this case as well, the resistance increases significantly. Therefore, it is appropriate for the ratio of the first porosity to the second porosity to be within the above range.

[0019] The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The non-aqueous electrolyte includes at least lithium hexafluorophosphate LiPF6 as the electrolyte salt. The non-aqueous electrolyte includes at least propylene carbonate (PC) as the non-aqueous solvent.

[0020] The ratio of the mass of LiPF6 to the mass of PC in the non-aqueous electrolyte (mass of LiPF6 / mass of PC) is 0.5 or more and 1.0 or less. By keeping the mass ratio of LiPF6 to PC within this range, gas generation can be suppressed. If the mass ratio is less than 0.5, the LiPF6 in the positive electrode is consumed by reaction, resulting in a shortage, which increases reaction irregularities at the positive electrode. As a result, gas generation increases. If the mass ratio exceeds 1.0, the viscosity of the non-aqueous electrolyte increases significantly, reducing the transportability of LiPF6 in the positive electrode and separator. This increases reaction irregularities within the battery and increases gas generation.

[0021] Next, details of the nonaqueous electrolyte battery according to the first embodiment will be described. The nonaqueous electrolyte battery can include an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator positioned between the positive electrode and the negative electrode. The positive electrode can include a positive electrode current collector tab electrically connected to the electrode assembly. Furthermore, the negative electrode can include a negative electrode current collector tab electrically connected to the electrode assembly.

[0022] Such a nonaqueous electrolyte battery may further include a housing member. The electrode group may be housed within the housing member. The housing member may house a nonaqueous electrolyte. The nonaqueous electrolyte may be impregnated into the electrode group housed within the housing member. The nonaqueous electrolyte battery may further include a positive electrode terminal and a negative electrode terminal electrically connected to the housing member. The positive electrode terminal may be electrically connected to a positive electrode current collector tab of the positive electrode. The negative electrode terminal may be electrically connected to a negative electrode current collector tab of the negative electrode.

[0023] The positive electrode, negative electrode, non-aqueous electrolyte, separator, exterior member, positive electrode terminal, and negative electrode terminal will be described in detail below.

[0024] positive electrode The positive electrode includes a positive electrode active material-containing layer. The positive electrode may further include a positive electrode current collector on which the positive electrode active material-containing layer is provided. When the positive electrode current collector has, for example, a sheet shape, the positive electrode active material-containing layer may be supported on at least one main surface of the positive electrode current collector. The positive electrode active material-containing layer includes single particles of the positive electrode active material represented by the above formula (1). The positive electrode active material-containing layer may include materials other than the positive electrode active material, such as a conductive agent or a binder.

[0025] The conductive agent can improve current collection performance and reduce contact resistance between the active material and the current collector. The conductive agent preferably contains a carbon material. Examples of carbon materials include acetylene black, ketjen black, furnace black, graphite, carbon nanotubes, and carbon nanofibers. The active material-containing layer can contain one or more of the above carbon materials.

[0026] The conductive agent has, for example, the shape of particles or fibers. The average particle size of the conductive agent particles is preferably 20 nm or more and 100 nm or less. The proportion of the conductive agent in the positive electrode active material-containing layer is preferably, for example, 3 mass % or more and 20 mass % or less.

[0027] Examples of binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluorine-based rubber. One or more types of binders may be used. The proportion of the binder in the positive electrode active material-containing layer is preferably 1% by mass or more and 1.8% by mass or less.

[0028] The density of the positive electrode active material-containing layer is 3.2 g / cm 3 More than 3.8g / cm 3 It is preferable that:

[0029] The positive electrode current collector may be, for example, a metal foil or an alloy foil. Examples of the metal foil include aluminum foil, stainless steel foil, and nickel foil. Examples of the alloy foil include aluminum alloy, copper alloy, and nickel alloy.

[0030] The positive electrode is produced, for example, by the following method. A positive electrode active material, a conductive agent, and a binder are kneaded together with a solvent (e.g., N-methylpyrrolidone (NMP)) to prepare a slurry. The obtained slurry is applied to a positive electrode current collector, dried, and then pressed to obtain a positive electrode. The voids in the positive electrode active material-containing layer can be adjusted by pressing with a load according to the composition of the positive electrode active material-containing layer. If necessary, a cutting step to a predetermined width may be performed before or after pressing.

[0031] negative electrode The negative electrode includes, for example, a negative electrode current collector and a negative electrode active material-containing layer formed on the negative electrode current collector. The negative electrode active material-containing layer may include a conductive agent and a binder in addition to the negative electrode active material.

[0032] The negative electrode active material, the conductive agent, the binder, and the negative electrode current collector will be described below.

[0033] The negative electrode active material has a potential of 0.4 V (vs. Li / Li) relative to the oxidation-reduction reaction potential of lithium. +) or more. In a non-aqueous electrolyte battery equipped with such a negative electrode, lithium deposition due to charge and discharge can be suppressed. Therefore, such a non-aqueous electrolyte battery has superior rapid charge and discharge performance. Examples of the negative electrode active material include Li 4+x Ti5O 12 Spinel-type lithium titanate represented by Li (where x varies in the range of -1≦x≦3 depending on the charge / discharge reaction). 2+x Ramsdellite-type lithium titanate represented by Ti3O7 (x varies in the range of -1≦x≦3 depending on the charge / discharge reaction), monoclinic niobium titanium composite oxide represented by Nb2TiO7, Li 2-x Ti6O 14 (x varies within the range of 0≦x≦6 depending on the charge / discharge reaction), or a metal composite oxide containing Ti and at least one element selected from the group consisting of P, V, Sn, Cu, Ni, and Fe is used. Examples of metal composite oxides containing Ti and at least one element selected from the group consisting of P, V, Sn, Cu, Ni, and Fe include TiO2-P2O5, TiO2-V2O5, TiO2-P2O5-SnO2, and TiO2-P2O5-MO (M is at least one element selected from the group consisting of Cu, Ni, and Fe). These metal composite oxides are converted into lithium-titanium composite oxides by intercalating lithium during charging. Among the lithium-titanium composite oxides, spinel-type lithium titanate is preferred due to its excellent cycle performance.

[0034] As a negative electrode active material, the oxidation-reduction reaction potential of lithium is 0.5 V (vs. Li / Li + It is more preferable that the titanium-containing oxide contains a titanium-containing oxide that exhibits a reaction potential for lithium ion insertion and deintercalation at a potential of 1000 kJ / cm or more. Examples of such titanium-containing oxides include spinel-type lithium titanate, ramsdellite-type lithium titanate, monoclinic niobium titanium composite oxide, and orthorhombic titanium-containing oxide, among the above-mentioned compounds.

[0035] The negative electrode active material may contain, for example, a carbonaceous material or a metal compound. Examples of the carbonaceous material include natural graphite, artificial graphite, coke, vapor-grown carbon fiber, mesophase pitch-based carbon fiber, spherical carbon, and resin-fired carbon. More preferable carbonaceous materials include vapor-grown carbon fiber, mesophase pitch-based carbon fiber, or spherical carbon. The carbonaceous material has an interlayer spacing d of the (002) plane by X-ray diffraction 002 preferably of 0.34 nm or less.

[0036] As the metal compound, a metal sulfide or a metal nitride can be used. Examples of the metal sulfide include titanium sulfide such as TiS2, molybdenum sulfide such as MoS2, and iron sulfide such as FeS, FeS2, or Li x FeS2 (iron sulfide where 0 ≦ x ≦ 2) can be used. Examples of the metal nitride include lithium cobalt nitride (e.g., Li s Co t N, 0 < s < 4, 0 < t < 0.5) can be used.) Examples of the conductive agent include carbonaceous materials such as acetylene black, carbon black, and graphite.

[0037] Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine-based rubber, and styrene-butadiene rubber.

[0038] When the negative electrode active material is a substance capable of occluding and releasing lithium ions, as the negative electrode current collector, a material that is electrochemically stable at the lithium ion occlusion and release potential of the negative electrode active material can be used. The negative electrode current collector is preferably a metal foil made of at least one selected from copper, nickel, stainless steel, and aluminum, or an alloy foil made of an aluminum alloy containing at least one element selected from Mg, Ti, Zn, Mn, Fe, Cu, and Si. The shape of the negative electrode current collector can be various according to the use of the battery.

[0039] The negative electrode can be produced, for example, by the following method. First, a negative electrode active material, a binder, and, if necessary, a conductive agent are suspended in a commonly used solvent, such as N-methylpyrrolidone, to prepare a slurry for producing the negative electrode. The resulting slurry is applied to a negative electrode current collector. The applied slurry is dried, and the dried coating is pressed to obtain a negative electrode comprising a negative electrode current collector and a negative electrode active material-containing layer formed on the negative electrode current collector.

[0040] Separator The separator is not particularly limited as long as it has insulating properties, and examples thereof include porous films or nonwoven fabrics made of polymers such as polyolefin, cellulose, polyethylene terephthalate, and vinylon. The separator may be made of one type of material or a combination of two or more types.

[0041] The second porosity of the separator can be, for example, 55% or more and 70% or less.

[0042] The thickness of the separator can be between 5 μm and 20 μm.

[0043] electrode group The electrode group may have, for example, a wound structure in which a stack of positive electrodes, separators, and negative electrodes is wound, or a stack structure in which multiple positive electrodes and multiple negative electrodes are alternately stacked with separators interposed therebetween, or the electrode group may have another structure.

[0044] non-aqueous electrolyte The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of the non-aqueous electrolyte include a liquid non-aqueous electrolyte.

[0045] The nonaqueous electrolyte contains at least LiPF as an electrolyte salt. In addition to LiPF, the electrolyte salt may further contain lithium salts such as LiBF (lithium tetrafluoroborate), Li(CF3SO2)2N (lithium bistrifluoromethanesulfonylamide; commonly known as LiTFSI), LiCF3SO3 (lithium trifluoromethanesulfonate; commonly known as LiTFS), Li(C2F5SO2)2N (lithium bispentafluoroethanesulfonylamide; commonly known as LiBETI), LiClO4, LiAsF6 (lithium hexafluoride), LiSbF6, lithium bisoxalatoborate {LiB(CO4)2, commonly known as LiBOB}, and lithium difluoro(trifluoro-2-oxido-2-trifluoro-methylpropionato(2-)-0,0)borate {LiBF2OCOOC(CF3)2, commonly known as LiBF2(HHIB)}. These other electrolyte salts may be used alone or in combination of two or more. Of the electrolyte salts contained in the non-aqueous electrolyte, LiPF6 preferably accounts for 80 mass% or more. The non-aqueous electrolyte may contain only LiPF6 as the electrolyte salt, in which case the content of LiPF6 in the electrolyte salt is 100 mass%.

[0046] The electrolyte salt concentration in the non-aqueous electrolyte is preferably in the range of 1 mol / L to 3 mol / L, inclusive. When the electrolyte salt concentration is in this range, it is possible to further improve performance when a high load current is passed through the non-aqueous electrolyte while suppressing the effect of increased viscosity due to an increase in the electrolyte salt concentration.

[0047] The nonaqueous solvent contains at least propylene carbonate (PC). In addition to PC, the nonaqueous solvent may further contain, for example, a cyclic carbonate (other than PC) such as ethylene carbonate (EC), a chain carbonate such as diethyl carbonate (DEC), dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), or dipropyl carbonate (DPC), 1,2-dimethoxyethane (DME), γ-butyrolactone (GBL), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeHF), 1,3-dioxolane, sulfolane, or acetonitrile (AN). These other solvents may be used alone or in combination.

[0048] Exterior materials The exterior member may be, for example, a laminate film or a metal container. The thickness of the laminate film and the metal container may each be 0.5 mm or less. Alternatively, the exterior member may be a resin container made of polyolefin resin, polyvinyl chloride resin, polystyrene resin, acrylic resin, phenol resin, polyphenylene resin, fluorine resin, or the like.

[0049] The shape of the exterior member, i.e., the battery shape, can be flat (thin), rectangular, cylindrical, coin, button, etc. The battery can be used for both small applications such as those installed in portable electronic devices and large applications such as those installed in two-wheeled to four-wheeled automobiles.

[0050] An example of a laminate film is a multilayer film containing a resin layer and a metal layer interposed between the resin layers. The metal layer is preferably aluminum foil or aluminum alloy foil for weight reduction. The resin layer can be made of a polymer material such as polypropylene (PP), polyethylene (PE), nylon, or polyethylene terephthalate (PET). The laminate film can be sealed by heat fusion and molded into the shape of the exterior component.

[0051] The metal container is made of aluminum or an aluminum alloy. The aluminum alloy preferably contains elements such as magnesium, zinc, silicon, etc. If the alloy contains transition metals such as iron, copper, nickel, or chromium, the amount of such metals is preferably 100 ppm or less.

[0052] Positive terminal A portion of the positive electrode terminal is electrically connected to a portion of the positive electrode, thereby serving as a conductor for transferring electrons between the positive electrode and an external circuit. The positive electrode terminal can be connected, for example, to a positive electrode current collector, particularly a positive electrode current collector tab. Alternatively, the positive electrode terminal can be connected, for example, to a positive electrode current collector tab via a positive electrode lead.

[0053] The positive electrode terminal is, for example, 3.0 V or more and 4.5 V or less with respect to the Li oxidation-reduction reaction potential (vs. Li / Li + The positive electrode terminal is preferably formed from a material that is electrically stable at high potential and has electrical conductivity. The positive electrode terminal is preferably formed from aluminum or an aluminum alloy containing one or more elements selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si.

[0054] The positive electrode terminal is preferably made of a material with high electrical conductivity. When connected to the positive electrode current collector, the positive electrode terminal is preferably made of the same material as the current collector. Using the same material can reduce the contact resistance between the positive electrode terminal and the positive electrode current collector. Similarly, the positive electrode lead is preferably made of the same material as the positive electrode terminal and the positive electrode current collector.

[0055] negative terminal A portion of the negative electrode terminal is electrically connected to a portion of the negative electrode, thereby serving as a conductor for transferring electrons between the negative electrode and an external circuit. The negative electrode terminal can be connected, for example, to a negative electrode current collector, particularly a negative electrode current collector tab. Alternatively, the negative electrode terminal can be connected, for example, to a negative electrode current collector tab via a negative electrode lead.

[0056] The negative terminal should be between 0.5V and 3.0V relative to the Li oxidation-reduction reaction potential (vs. Li / Li + The negative electrode terminal is preferably formed from a material that is electrically stable at high potential and has electrical conductivity. The negative electrode terminal is preferably formed from aluminum or an aluminum alloy containing one or more elements selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si.

[0057] The negative electrode terminal is preferably made of a material with high electrical conductivity. When connected to the negative electrode current collector, the negative electrode terminal is preferably made of the same material as the current collector. Using the same material can reduce the contact resistance between the negative electrode terminal and the negative electrode current collector. Similarly, the negative electrode lead is preferably made of the same material as the negative electrode terminal and the negative electrode current collector.

[0058] Next, an example of such a nonaqueous electrolyte battery will be described in more detail with reference to the drawings.

[0059] FIG. 1 is an exploded perspective view of an example of a nonaqueous electrolyte battery 100 according to an embodiment. The battery shown in FIG. 1 is a sealed prismatic nonaqueous electrolyte battery. The illustrated nonaqueous electrolyte battery 100 includes an outer can 1, a lid 2, a positive electrode external terminal 3, a negative electrode external terminal 4, and an electrode group 5. The outer can 1 and the lid 2 form an outer casing member. The outer can 1 has a bottomed rectangular cylindrical shape and is made of a metal such as aluminum, an aluminum alloy, iron, or stainless steel.

[0060] FIG. 2 is a partially exploded perspective view of an electrode group used in the nonaqueous electrolyte battery 100 shown in FIG. 2. As shown in FIG. 2, the flat electrode group 5 is formed by winding a positive electrode 6 and a negative electrode 7 in a flat shape with a separator 8 interposed therebetween. The positive electrode 6 includes a strip-shaped positive electrode current collector made of, for example, metal foil, a positive electrode current collector tab 6a formed at one end parallel to the long side of the positive electrode current collector, and a positive electrode active material-containing layer 6b formed on the positive electrode current collector except for at least the area of ​​the positive electrode current collector tab 6a. Meanwhile, the negative electrode 7 includes a strip-shaped negative electrode current collector made of, for example, metal foil, a negative electrode current collector tab 7a formed at one end parallel to the long side of the negative electrode current collector, and a negative electrode active material-containing layer 7b formed on the negative electrode current collector except for at least the area of ​​the negative electrode current collector tab 7a.

[0061] The positive electrode 6, separator 8, and negative electrode 7 are wound with the positive electrode 6 and negative electrode 7 offset from each other so that the positive electrode current collector tab 6a protrudes from the separator 8 in the direction of the winding axis of the electrode group, and the negative electrode current collector tab 7a protrudes from the separator 8 in the opposite direction. As a result of this winding, the electrode group 5 has the spirally wound positive electrode current collector tab 6a protruding from one end face, and the spirally wound negative electrode current collector tab 7a protruding from the other end face, as shown in Fig. 2. The electrode group 5 is impregnated with a nonaqueous electrolyte (not shown).

[0062] As shown in Fig. 1, the positive electrode current collector tabs 6a and the negative electrode current collector tabs 7a are each divided into two bundles, with the boundary near the winding center of the electrode group. The conductive clamping member 9 has first and second clamping portions 9a and 9b each having a substantially U-shape, and a connecting portion 9c that electrically connects the first clamping portion 9a and the second clamping portion 9b. One bundle of the positive and negative electrode current collector tabs 6a and 7a is clamped by the first clamping portion 9a, and the other bundle is clamped by the second clamping portion 9b.

[0063] The positive electrode lead 10 has a substantially rectangular support plate 10a, a through hole 10b opened in the support plate 10a, and strip-shaped current collecting portions 10c and 10d that branch into two from the support plate 10a and extend downward. On the other hand, the negative electrode lead 11 has a substantially rectangular support plate 11a, a through hole 11b opened in the support plate 11a, and strip-shaped current collecting portions 11c and 11d that branch into two from the support plate 11a and extend downward.

[0064] The positive electrode lead 10 sandwiches the clamping member 9 between the current collecting portions 10c and 10d. The current collecting portion 10c is disposed in the first clamping portion 9a of the clamping member 9. The current collecting portion 10d is disposed in the second clamping portion 9b. The current collecting portions 10c and 10d, the first and second clamping portions 9a and 9b, and the positive electrode current collecting tab 6a are joined by, for example, ultrasonic welding. This electrically connects the positive electrode 6 of the electrode group 5 and the positive electrode lead 10 via the positive electrode current collecting tab 6a.

[0065] The negative electrode lead 11 sandwiches the clamping member 9 between the current collecting portions 11c and 11d. The current collecting portion 11c is disposed in the first clamping portion 9a of the clamping member 9. The current collecting portion 11d is disposed in the second clamping portion 9b. The current collecting portions 11c and 11d, the first and second clamping portions 9a and 9b, and the negative electrode current collecting tab 7a are joined by, for example, ultrasonic welding. This electrically connects the negative electrode 7 of the electrode group 5 and the negative electrode lead 11 via the negative electrode current collecting tab 7a.

[0066] The materials of the positive and negative electrode leads 10, 11 and the clamping member 9 are not particularly specified, but are preferably the same as those of the positive and negative electrode external terminals 3, 4, respectively. The positive electrode external terminal 3 is made of, for example, aluminum or an aluminum alloy. The negative electrode external terminal 4 is made of, for example, aluminum, an aluminum alloy, copper, nickel, or nickel-plated iron. For example, if the external terminals are made of aluminum or an aluminum alloy, the leads are preferably made of aluminum or an aluminum alloy. Furthermore, if the external terminals are made of copper, the leads are preferably made of copper or the like.

[0067] The rectangular plate-shaped lid 2 is seam-welded to the opening of the outer can 1, for example, by laser. The lid 2 is made of a metal such as aluminum, an aluminum alloy, iron, or stainless steel. The lid 2 and the outer can 1 are preferably made of the same type of metal. The positive electrode external terminal 3 is electrically connected to the support plate 10a of the positive electrode lead 10. The negative electrode external terminal 4 is electrically connected to the support plate 11a of the negative electrode lead 11. The insulating gasket 12 is disposed between the positive and negative electrode external terminals 3, 4 and the lid 2, and electrically insulates the positive and negative electrode external terminals 3, 4 from the lid 2. The insulating gasket 12 is preferably a resin molded product.

[0068] <Various measurement methods> The methods for measuring the first porosity, the second porosity, the composition of the active material, and the composition of the non-aqueous electrolyte will be described below. First, the method for removing the electrodes from the battery will be described.

[0069] First, prepare the battery to be measured. The battery to be measured must have a discharge capacity of 80% or more of its rated capacity. In other words, batteries that have deteriorated excessively will not be measured.

[0070] Next, the prepared battery is discharged until the open circuit voltage reaches 2.0 V to 2.2 V. Next, the discharged battery is transferred into a glove box filled with argon, the dew point of the internal atmosphere of which is -70°C. The battery is opened in the glove box. The electrode group is removed from the cut-open battery. If the removed electrode group includes a positive electrode lead and a negative electrode lead, the positive electrode lead and the negative electrode lead are cut off, taking care not to short-circuit the positive electrode and the negative electrode.

[0071] Next, the electrode group is disassembled into a positive electrode, a negative electrode, and a separator. Each electrode thus obtained is washed using diethyl carbonate as a solvent. In this washing, the disassembled components are completely immersed in the diethyl carbonate solvent and left in that state for 60 minutes.

[0072] After cleaning, the electrodes are subjected to vacuum drying. During vacuum drying, the pressure is reduced from atmospheric pressure to -97 kPa or more in a 25°C environment, and this state is maintained for 10 minutes. The electrodes removed in this manner are measured using the following method.

[0073] 1st porosity The first porosity of the positive electrode active material-containing layer can be measured by mercury intrusion porosimetry, the details of which are as follows.

[0074] A plurality of rectangular measurement samples are cut from the positive electrode. The dimensions of the measurement samples are, for example, 1.25 cm x 2.50 cm. Next, the mass of the cut measurement samples is measured. Next, 16 measurement samples are placed in the cell of the measurement device. These measurement samples are measured under conditions of an initial pressure of approximately 10 kPa (approximately 1.5 psia, equivalent to a pore diameter of approximately 120 μm) and a maximum pressure of 414 MPa (approximately 59986 psia, equivalent to a pore diameter of approximately 0.003 μm) to obtain a pore distribution curve for the positive electrode. As the measurement device, for example, a Shimadzu Micromeritics Pore Distribution Measurement Device Autopore 9520 is used.

[0075] Next, the positive electrode active material-containing layer is peeled off from another measurement sample cut out from the same positive electrode using, for example, a spatula to obtain a current collector piece. The mass of this current collector piece is then measured. The mass of the active material-containing layer contained in the measurement sample is then obtained by subtracting the mass of the current collector piece from the mass of the measurement sample. The pore distribution curve of the positive electrode obtained by the above method is then recalculated and converted into a pore distribution curve of the positive electrode active material-containing layer. In this way, the pore distribution curve of the active material-containing layer is obtained. The pore volume per 1 g of the positive electrode active material-containing layer can be calculated from the pore distribution obtained as above and the mass of the positive electrode active material-containing layer. The first porosity is obtained by dividing the obtained pore volume (mL / g) by the volume per 1 g of the positive electrode active material-containing layer.

[0076] 2nd porosity The second porosity of the separator can also be measured by mercury intrusion porosimetry, as follows.

[0077] Multiple strip-shaped measurement samples are cut from the separator. The dimensions of the measurement samples are, for example, 1.25 cm x 2.50 cm. Next, the mass of the cut measurement samples is measured. Next, 16 measurement samples are placed in the cell of the measurement device. These measurement samples are measured under conditions of an initial pressure of approximately 10 kPa (approximately 1.5 psia, equivalent to a pore diameter of approximately 120 μm) and a maximum pressure of 414 MPa (approximately 59,986 psia, equivalent to a pore diameter of approximately 0.003 μm) to obtain a pore distribution curve of the separator. As a measurement device, for example, a Shimadzu Micromeritics Pore Distribution Measurement Device Autopore 9520 is used. The pore volume per 1 g of separator can be calculated from the obtained pore distribution. The porosity is obtained by dividing the obtained pore volume (mL / g) by the volume per 1 g of separator.

[0078] Active material composition The composition of the active material can be obtained by measuring the surface of the electrode removed from the battery using X-ray fluorescence (XRF) in the manner described above.

[0079] Composition of non-aqueous electrolyte The battery is discharged until the open circuit voltage reaches 2.0V to 2.2V. Next, the discharged battery is transferred to an argon-filled glove box with an internal atmosphere having a dew point of -70°C. The battery is opened in the glove box. The electrodes are removed from the cut-open battery. The removed electrodes are squeezed to extract the electrolyte. If the amount extracted is small, the electrolyte is extracted using acetonitrile. The obtained electrolyte is analyzed by GC-MS (gas chromatography-mass spectrometry) to determine the propylene carbonate (PC) content, and the LiPF6 content is obtained by capillary electrophoresis. The LiPF6 / PC ratio is calculated from the respective contents obtained.

[0080] The nonaqueous electrolyte battery according to the first embodiment includes a positive electrode including a positive electrode active material-containing layer containing single particles of the positive electrode active material represented by formula (1) and having a first porosity of 10% to 25%, a separator having a second porosity of 2.2 to 2.8 relative to the first porosity, and a nonaqueous electrolyte containing LiPF and propylene carbonate (PC) in a mass ratio (LiPF / PC) of 0.5 to 1.0. Therefore, this battery can suppress gas generation and resistance increase even during cycles at high potential.

[0081] (Second embodiment) According to a second embodiment, a battery pack including a battery is provided. The battery uses the nonaqueous electrolyte battery according to the first embodiment. The number of cells included in the battery pack can be one or more.

[0082] A plurality of batteries can be electrically connected in series, in parallel, or in a combination of series and parallel to form a battery assembly. A battery pack may include a plurality of battery assembly.

[0083] The battery pack may further include a protection circuit. The protection circuit has the function of controlling the charging and discharging of the battery. Furthermore, a circuit included in a device that uses the battery pack as a power source (e.g., electronic equipment, automobile, etc.) may be used as the protection circuit for the battery pack.

[0084] The battery pack may further include external current-carrying terminals. The external current-carrying terminals are used to output current from the battery to the outside and input current to the battery. In other words, when the battery pack is used as a power source, current is supplied to the outside through the external current-carrying terminals. When the battery pack is charged, charging current (including regenerative energy from the vehicle's power) is supplied to the battery pack through the external current-carrying terminals.

[0085] Next, an example of a battery pack according to a second embodiment will be described with reference to the drawings. Fig. 3 is a block diagram showing an example of an electric circuit of the battery pack according to the embodiment.

[0086] The battery pack shown in Fig. 3 includes a plurality of flat-type cells 100 having the structure shown in Fig. 1 and Fig. 2. These cells 100 are electrically connected in series with one another as shown in Fig. 3.

[0087] In addition to the cell 100, the battery pack is equipped with a thermistor 25, a protection circuit 26, and an external terminal 27 for applying current.

[0088] At one end of the series connection, a positive electrode lead 28 is connected to the positive electrode external terminal of the cell 100. The positive electrode lead 28 is electrically connected to the protection circuit 26 via a positive electrode connector 29 and wiring 32. At the other end of the series connection, a negative electrode lead 30 is connected to the negative electrode external terminal of the cell 100. The negative electrode lead 30 is electrically connected to the protection circuit 26 via a negative electrode connector 31 and wiring 33.

[0089] The thermistor 25 detects the temperature of each cell 100 and transmits the detection signal to the protection circuit 26. The protection circuit 26 can interrupt the positive wiring 34a and the negative wiring 34b between the protection circuit 26 and the external terminal 27 for current application under predetermined conditions. An example of the predetermined condition is when a signal is received from the thermistor 25 indicating that the temperature of the cell 100 is equal to or higher than a predetermined temperature. Another example of the predetermined condition is when overcharge, overdischarge, overcurrent, or the like of a cell 100 is detected. This overcharge detection is performed for each cell 100 or for all cells 100. When detecting an individual cell 100, the battery voltage or the positive or negative electrode potential may be detected. In the latter case, a lithium electrode used as a reference electrode is inserted into each cell 100. In the battery pack shown in FIG. 3, each cell 100 is connected to a voltage detection wire 35, and a detection signal is transmitted to the protection circuit 26 through these wires 35.

[0090] Although the illustrated battery pack has a configuration in which a plurality of cells 100 are connected in series, the battery pack may also have a plurality of cells 100 connected in parallel to increase battery capacity. Alternatively, the battery pack may have a plurality of cells 100 connected in a combination of series and parallel connections. Assembled battery packs may also be connected in series or parallel.

[0091] Furthermore, although the illustrated battery pack includes a plurality of unit cells 100, the battery pack according to the second embodiment may include a single unit cell 100.

[0092] The battery pack configuration may be changed as appropriate depending on the intended use. Preferred uses of the battery pack are those that require good cycle performance when drawing a large current. Specific examples include power sources for digital cameras and in-vehicle applications such as two- to four-wheel hybrid electric vehicles, two- to four-wheel electric vehicles, and power-assisted bicycles. In-vehicle applications are particularly preferred.

[0093] In an automobile equipped with a battery pack according to this embodiment, the battery pack recovers, for example, regenerative energy for powering the automobile.

[0094] The battery pack according to the second embodiment described above in detail includes the nonaqueous electrolyte battery according to the first embodiment, and therefore, this battery pack can suppress gas generation and resistance increase even during cycles at high potential. [Example]

[0095] <Fabrication of non-aqueous electrolyte battery> Example 1 (Preparation of positive electrode) Lithium-containing nickel-cobalt-manganese composite oxide LiNi formed as a single particle as the active material 0.8 Co 0.1 Mn 0.1 The average particle diameter (D 50The particle size was 4 μm. Acetylene black was used as a conductive agent, and polyvinylidene fluoride was used as a binder. The active material, conductive agent, and binder were dissolved and mixed in N-methylpyrrolidone (NMP) in a mass ratio of 93:5:2 to prepare a paste.

[0096] The specific method for preparing the paste is described below. The active material and conductive agent were mixed using a Henschel mixer to form a composite (compound) of the active material and conductive agent. The resulting composite and binder were dispersed in NMP and kneaded using a planetary mixer with a capacity of 20 L. To avoid a sudden increase in viscosity, each material was added to the NMP little by little. Kneading was performed under high-pressure conditions with a non-volatile content (NV) of 78.5%. The kneaded mixture was then transferred to a bead mill with a capacity of 2 L and mixed at a bead rotation speed of 800 rpm to prepare a paste.

[0097] A paste-like dispersion liquid was used as a positive electrode coating liquid and uniformly applied to both the front and back surfaces of a strip-shaped current collector made of aluminum foil. The coating film of the positive electrode coating liquid was dried to form a positive electrode active material-containing layer. After drying, the strip was press-molded under the following conditions: a press roll made of hard chrome-plated steel with a press roll diameter of 350 mm was used, and the press load was set to approximately 8 kN / cm. A positive electrode with a first porosity of 24.6% was obtained by rolling. The rolled electrode was cut to the specified dimensions, and a current collecting tab was welded to obtain a positive electrode.

[0098] (Preparation of negative electrode) Li4Ti5O as the negative electrode active material 12A spinel-type lithium titanium oxide represented by the formula (I), graphite as a conductive agent, and polyvinylidene fluoride as a binder were prepared. These negative electrode active materials, conductive agent, and binder were dissolved and mixed in NMP in a mass ratio of 94:4:2 to prepare a paste. This paste was used as a negative electrode coating solution and uniformly applied to both the front and back surfaces of a negative electrode current collector made of strip-shaped aluminum foil. The negative electrode coating solution was dried to form a negative electrode active material-containing layer. The dried strip was press-molded and then cut to the specified dimensions. The electrode thickness was adjusted to 130 μm. A current collecting tab was welded to the negative electrode to obtain the negative electrode.

[0099] (Preparation of electrode groups) Two nonwoven separators made of cellulose were prepared. Each separator had a thickness of 8 μm and a second porosity of 65%. Next, one separator, a positive electrode, the other separator, and a negative electrode were stacked in this order to form a laminate. The resulting laminate was wound so that the separator was positioned at the outermost periphery to obtain a wound body. The resulting wound body (coil) was then pressed while being heated. In this way, a wound electrode group was produced.

[0100] (Preparation of non-aqueous electrolyte) A non-aqueous solvent was prepared by mixing propylene carbonate and diethyl carbonate in a volume ratio of 1:2. LiPF was dissolved in this mixed solvent as an electrolyte salt to a concentration of 1.5 mol / L to prepare a non-aqueous electrolyte. The mass ratio of LiPF to propylene carbonate (PC) in the resulting non-aqueous electrolyte was 0.7.

[0101] (Battery assembly) Electrode terminals were attached to the positive and negative electrodes of the wound electrode assembly obtained as described above. The electrode assembly was placed in an aluminum rectangular container. The nonaqueous electrolyte was poured into the container, and the container was sealed to obtain a nonaqueous electrolyte battery. The nonaqueous electrolyte battery was designed to have a nominal capacity of 26 Ah.

[0102] Example 2 The rolling conditions during the preparation of the positive electrode were changed so that the first porosity of the positive electrode was 19.6%, and the separator was changed to a cellulose nonwoven fabric separator having a second porosity of 55%. Aside from these changes, a nonaqueous electrolyte battery was prepared in the same manner as in Example 1.

[0103] Example 3 The rolling conditions during the preparation of the positive electrode were changed so that the first porosity of the positive electrode was 25%, and the separator was changed to a cellulose nonwoven fabric separator having a second porosity of 55%. Aside from these changes, a nonaqueous electrolyte battery was prepared in the same manner as in Example 1.

[0104] Example 4 The rolling conditions during positive electrode preparation were changed so that the first porosity of the positive electrode was 25%, and the separator was changed to a cellulose nonwoven fabric separator having a second porosity of 55%. Furthermore, the LiPF concentration was increased so that the LiPF / PC mass ratio was 0.9. A nonaqueous electrolyte battery was prepared in the same manner as in Example 1, except for these changes.

[0105] Example 5 The rolling conditions during the preparation of the positive electrode were changed so that the first porosity of the positive electrode was 16%, and the separator was changed to a cellulose nonwoven fabric separator having a second porosity of 44%. Aside from these changes, a nonaqueous electrolyte battery was prepared in the same manner as in Example 1.

[0106] Example 6 The rolling conditions during the preparation of the positive electrode were changed so that the first porosity of the positive electrode was 11%, and the separator was changed to a cellulose nonwoven fabric separator having a second porosity of 30%. Aside from these changes, a nonaqueous electrolyte battery was prepared in the same manner as in Example 1.

[0107] (Comparative Example 1) The positive electrode active material is a lithium-containing nickel-cobalt-manganese composite oxide (LiNi) formed from secondary particles. 0.8 Co 0.1 Mn 0.1A nonaqueous electrolyte battery was fabricated in the same manner as in Example 1, except that O2 was used instead.

[0108] (Comparative Examples 2 and 3) A nonaqueous electrolyte battery was produced in the same manner as in Example 1, except that the rolling conditions during production of the positive electrode were changed so that the first porosity of the positive electrode would have the value shown in Table 1 below.

[0109] (Comparative Examples 4 and 5) A nonaqueous electrolyte battery was fabricated in the same manner as in Example 1, except that the concentration of LiPF6 was changed so that the LiPF6 / PC mass ratio was the value shown in Table 1 below.

[0110] (Comparative Examples 6 and 7) A nonaqueous electrolyte battery was fabricated in the same manner as in Example 1, except that the separator was changed to a cellulose nonwoven fabric separator having a second porosity shown in Table 1 below.

[0111] Each battery was charged at 2C from 0% SOC (state of charge) to 100% SOC in a 45°C environment, and then discharged at 2C from 100% SOC to 0% SOC for 1000 cycles. The amount of gas generated during the 1000 cycles and the rate of increase in resistance after 1000 cycles were measured. The results are shown in Table 1. For both the amount of gas generated and the rate of increase in resistance during repeated charge-discharge cycles, the value measured in Example 1 was set to 100, and the measurement results for the other Examples and Comparative Examples are shown as relative values ​​to this standard.

[0112] The amount of gas generated was measured and calculated as follows. It was calculated from the change in cell volume of the battery before and after charge / discharge cycles. The cell volume was calculated using Archimedes' principle by charging the battery at 1C in a 25°C environment until the state of charge (SOC) reached 50%, then submerging it in water.

[0113] The resistance increase rate was measured and calculated as follows. The resistance increase rate was calculated from the ratio of the discharge resistance values ​​before and after the charge-discharge cycle. The discharge resistance was measured after charging at 1 C in an environment of 25°C until the state of charge (SOC) reached 50%, and then discharging at 10 C for 0.2 seconds.

[0114] Table 1 shows the particle shape of the positive electrode active material particles, the first porosity in the positive electrode, the second porosity of the separator, the ratio between the first and second porosities, the mass ratio of LiPF to PC in the non-aqueous electrolyte, and the above measurement results. The particle shape of the positive electrode active material is indicated as either a single particle or containing secondary particles.

[0115] [Table 1]

[0116] As shown in Table 1, in Example 1-X, both the amount of gas generated during cycling and the rate of increase in resistance were suppressed to the same extent. In contrast, in Comparative Examples 1 and 3, both the amount of gas generated and the rate of increase in resistance increased significantly. In Comparative Examples 2, 4, and 5, the amount of gas generated increased, and in Comparative Examples 6 and 7, the rate of increase in resistance was high.

[0117] From Comparative Example 1, it can be seen that when the positive electrode active material is in the form of secondary particles, the first porosity of the positive electrode active material-containing layer becomes high, and the amount of gas generated and the rate of increase in resistance increase.

[0118] From Comparative Examples 2 and 3, it can be seen that gas generation increases when the first porosity of the positive electrode active material-containing layer is either too low or too high.

[0119] From Comparative Examples 4 and 5, it can be seen that if the ratio of LiPF6 to PC in the electrolyte is too large or too small, the reaction becomes uneven and gas generation increases.

[0120] From Comparative Examples 6 and 7, it can be seen that the resistance increases greatly when the second porosity of the separator is too low or too high compared to the first porosity of the positive electrode active material.

[0121] According to at least one of the embodiments and examples described above, a non-aqueous electrolyte battery is provided. The non-aqueous electrolyte battery includes a positive electrode, a negative electrode, a separator interposed therebetween, and a non-aqueous electrolyte. The positive electrode includes a positive electrode active material-containing layer containing single particles of a positive electrode active material represented by the following formula (1). The active material-containing layer has a first porosity of 10% or more and 25% or less, measured by mercury porosimetry. The non-aqueous electrolyte includes LiPF6 and propylene carbonate. The mass ratio of LiPF6 to propylene carbonate in the non-aqueous electrolyte is 0.5 or more and 1.0 or less. The separator has a second porosity of 2.2 or more and 2.8 or less, measured by mercury porosimetry, as a ratio to the first porosity of the active material-containing layer. Li a Ni (1-b-c-d) Co b Mn c M d O2(1) Here, 1≦a≦1.2, 0≦b≦0.4, 0≦c≦0.4, 0≦d≦0.1, and M is one or more elements selected from the group consisting of Fe, Cu, Ti, Mg, Al, W, Y, B, Mo, Nb, Zn, Sn, Zr, Ga, and V.

[0122] According to the nonaqueous electrolyte battery, gas generation and an increase in resistance can be suppressed even during charge-discharge cycles at a high potential.

[0123] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the inventions and their equivalents as defined in the claims.

[0124] Several embodiments of the present invention will be described below. [1] A positive electrode including a positive electrode active material-containing layer that includes single particles of a positive electrode active material represented by the following formula (1) and has a first porosity of 10% or more and 25% or less; a negative electrode; a separator between the positive electrode and the negative electrode; a non-aqueous electrolyte containing LiPF6 and propylene carbonate, wherein the mass ratio of the LiPF6 to the propylene carbonate is 0.5 or more and 1.0 or less; Equipped with A nonaqueous electrolyte battery, wherein the ratio of the second porosity of the separator to the first porosity is 2.2 or more and 2.8 or less: Li a Ni (1-b-c-d) Co b Mn c M d O2(1) Here, 1≦a≦1.2, 0≦b≦0.4, 0≦c≦0.4, 0≦d≦0.1, and M is one or more elements selected from the group consisting of Fe, Cu, Ti, Mg, Al, W, Y, B, Mo, Nb, Zn, Sn, Zr, Ga, and V. [2] The nonaqueous electrolyte battery according to [1], wherein the second porosity is 55% or more and 70% or less. [3] The nonaqueous electrolyte battery according to [1] or [2], wherein the negative electrode contains a negative electrode active material that exhibits a reaction potential for insertion and deintercalation of lithium ions at a potential of 0.5 V (vs. Li / Li+) or more relative to the oxidation-reduction reaction potential of lithium. [4] A battery pack including the nonaqueous electrolyte battery according to any one of [1] to [3]. [Explanation of symbols]

[0125] 1... outer can, 2... lid, 3... positive electrode external terminal, 4... negative electrode external terminal, 5... electrode group, 6... positive electrode, 6a... positive electrode current collecting tab, 6b... positive electrode active material containing layer, 7... negative electrode, 7a... negative electrode current collecting tab, 7b... negative electrode active material containing layer, 8... separator, 9... clamping member, 9a... first clamping portion, 9b... second clamping portion, 9c... connecting portion, 10... positive electrode lead, 10a... support plate, 10b... through hole, 10c... current collecting portion, 10d... current collecting portion, 11...negative electrode lead, 11a...support plate, 11b...through hole, 11c...current collecting portion, 11d...current collecting portion, 12...insulating gasket, 25...thermistor, 26...protective circuit, 27...external terminal for current supply, 28...positive electrode lead, 29...positive electrode connector, 30...negative electrode lead, 31...negative electrode connector, 32...wiring, 33...wiring, 34a...positive electrode wiring, 34b...negative electrode wiring, 35...wiring, 100...single cell.

Claims

1. a positive electrode including a positive electrode active material-containing layer that includes single particles of a positive electrode active material represented by the following formula (1) and has a first porosity of 10% or more and 25% or less; a negative electrode; a separator between the positive electrode and the negative electrode; LiPF 6 and propylene carbonate, wherein the LiPF 6 and a non-aqueous electrolyte having a mass ratio of 0.5 to 1.0, A nonaqueous electrolyte battery, wherein the ratio of the second porosity of the separator to the first porosity is 2.2 or more and 2.8 or less: Li a Ni (1-b-c-d) Co b Mn c M d O 2 (1) Here, 1≦a≦1.2, 0<b≦0.4, 0<c≦0.4, 0≦d≦0.1, and M is one or more elements selected from the group consisting of Fe, Cu, Ti, Mg, Al, W, Y, B, Mo, Nb, Zn, Sn, Zr, Ga, and V.

2. 2. The nonaqueous electrolyte battery according to claim 1, wherein the second porosity is 55% or more and 70% or less.

3. The negative electrode has a potential of 0.5 V (vs. Li / Li) relative to the oxidation-reduction reaction potential of lithium. + 2. The nonaqueous electrolyte battery according to claim 1, comprising a negative electrode active material that exhibits a reaction potential for lithium ion insertion and deintercalation at a potential of 1000 V or more.

4. A battery pack comprising the nonaqueous electrolyte battery according to claim 1.

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