JP2013110134A - Nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte battery that offers excellent high-current output characteristics when the SOC is low.SOLUTION: The nonaqueous electrolyte battery includes a positive electrode 3 including a positive electrode active material layer that contains a positive electrode active material containing a lithium-manganese complex oxide, and a positive electrode collector on which the positive electrode active material layer is formed; a negative electrode 4 containing a negative electrode active material that undergoes a charge-discharge reaction at a potential of 1 V or higher relative to lithium; a solvent containing diethyl carbonate; and a nonaqueous electrolyte containing LiPFand LiBFdissolved in the solvent. The molarity of LiPFis higher than the molarity of LiBF.

Description

  The present invention relates to a non-aqueous electrolyte battery.

  A non-aqueous electrolyte battery using a positive electrode including a lithium manganese composite oxide and another lithium-containing composite oxide as a positive electrode active material is known (Patent Document 1). Here, the lithium manganese composite oxide has a feature that there is little difference in diffusion resistance of lithium ions in the solid with respect to the state of charge (SOC), so that a large current discharge of 25 C or more is performed in a low SOC state. In this case, it can be expected that the discharge characteristics are improved by including the lithium manganese composite oxide in the positive electrode. However, the lithium manganese composite oxide has a property that manganese in the active material is likely to be eluted when the SOC is low. Further, when the dissolved manganese is deposited on the negative electrode, the negative electrode resistance is increased, so that the large current characteristic in a state where the SOC is low is not improved.

JP 2003-197180 A

  It is an object of the present invention to provide a non-aqueous electrolyte battery with improved large current output characteristics when SOC is low.

A nonaqueous electrolyte battery according to the present invention includes a positive electrode active material-containing layer containing a positive electrode active material containing a lithium manganese composite oxide, and a positive electrode current collector on which the positive electrode active material-containing layer is formed,
A negative electrode including a negative electrode active material that performs a charge / discharge reaction at a potential of 1 V or more with respect to lithium;
A solvent containing diethyl carbonate; and a nonaqueous electrolyte containing LiPF ₆ and LiBF ₄ dissolved in the solvent, wherein the molar concentration of LiPF ₆ is larger than the molar concentration of LiBF _4. Features.

  According to the present invention, it is possible to provide a non-aqueous electrolyte battery with improved large current output characteristics when SOC is low.

1 is a partially cutaway cross-sectional view showing a square nonaqueous electrolyte secondary battery according to an embodiment of the present invention. Sectional drawing in alignment with the AA of the secondary battery of FIG. The expanded sectional view about the principal part of the secondary battery of FIG.

  According to the present invention, it is possible to improve a large current output characteristic of 25C or more when SOC is low. As a result of intensive studies to solve the above problems, it is possible to provide an SOC by including a positive electrode including a lithium manganese composite oxide and a negative electrode including a negative electrode active material that performs a charge / discharge reaction with respect to lithium at a potential of 1 V or higher. It has been found that the large current discharge characteristics are improved when the temperature is low. First, it was speculated that the dominant factor of the large current discharge characteristics at low SOC was the lithium ion diffusion resistance in the solid of the positive electrode. Here, it is known that the lithium ion diffusion resistance in the solid of the lithium-containing composite oxide that occludes and releases lithium ions has SOC dependency, and the lithium ion diffusion resistance in the solid greatly increases as the SOC decreases. Is common. Here, the lithium manganese composite oxide has a feature that the SOC dependency of the diffusion resistance of lithium ions in the solid is smaller than that of the lithium-containing composite oxide that occludes and releases other lithium ions. However, when this lithium manganese composite oxide is kept in a state where the SOC is low, manganese in the active material is eluted into the electrolyte. Up until now, it was thought that the discharge characteristics in the low SOC state were not improved even when using a lithium manganese composite compound with low diffusion resistance of lithium ions in the solid state with a low SOC. It was. However, it was revealed that the performance improvement at low SOC was not realized because the eluted manganese was deposited on the negative electrode and the negative electrode resistance was increased. Thus, it was found that the use of a negative electrode active material that performs a charge / discharge reaction with respect to lithium at a potential of 1 V or higher improves the large current discharge characteristics when the SOC is low. Furthermore, when lithium manganese composite oxide and other lithium oxides are included, the amount of lithium manganese composite oxide is more on the electrode surface side closer to the separator than on the current collector side, so that the state of charge is increased. It was confirmed that the effect of improving the large current discharge characteristics at a low time was great. This is because the lithium ion diffusion in the active material and in the non-aqueous electrolyte is the rate-determining step during high-current discharge, so the non-aqueous electrolyte is placed near the non-aqueous electrolyte bulk so that the lithium ion diffusion in the active material is fast. This is thought to be because the diffusion of lithium ions inside can be accelerated.

Here, the effect of the present invention is easily obtained as the battery has a structure in which manganese is more easily eluted. Therefore, when a non-aqueous electrolyte having a composition that is more likely to generate free acid is selected, the free acid becomes a trigger for elution of manganese, so that the effect is easily obtained. Nonaqueous electrolytes that are more likely to generate free acid include those that contain both LiPF ₆ and LiBF _{4 in} the lithium salt and diethyl carbonate in the solvent. The mechanism by which the non-aqueous electrolyte having this configuration is likely to generate free acid is not clear, but this configuration is because the decomposition reaction of PF ₆ ⁻ shown in (A) below in the non-aqueous electrolyte is more likely to proceed. I believe. For this reason, when the LiPF ₆ molar concentration in the non-aqueous electrolyte is larger than the LiBF ₄ molar concentration, significant improvement in output characteristics can be expected.

^{_{PF 6 - → PF 5 + F}} - (A)
In addition, although a large current differs depending on the electrode configuration, for example, a current value of 25C or more is assumed. At current values larger than this, the lithium ion diffusion resistance in the positive electrode solid affects the discharge characteristics. At a discharge current lower than that, the supply rate of lithium ions to the active material surface is considered to be the rate-limiting step. When such a large current is used, the usage is such that the battery capacity is not used up, but a battery capacity of several to 10% is used. Therefore, a battery having a configuration capable of achieving a high output even in a low state of charge as described in the present invention has a wide range of charge states that can be used in a large current discharge. In a battery pack that maintains the output characteristics of the time, the number of parallel batteries can be reduced, and as a result, a battery pack that combines light weight and low cost can be obtained.

  Hereinafter, the nonaqueous electrolyte battery according to the present invention will be described in detail for each member.

1) Positive Electrode This positive electrode has a positive electrode current collector and a positive electrode active material-containing layer that is supported on one or both surfaces of the current collector and contains an active material, a conductive agent, and a binder.

  For this positive electrode, for example, a conductive agent and a binder are added to the positive electrode active material, these are suspended in an appropriate solvent, and this suspension is applied to a current collector such as an aluminum foil, dried and pressed. It is produced by forming a strip electrode.

  The positive electrode active material preferably includes a plurality of lithium-containing composite oxides that occlude and release lithium, and preferably includes a lithium manganese composite oxide as an active material. The lithium manganese composite oxide is a kind of lithium-containing composite oxide that absorbs and releases lithium.

The lithium manganese composite oxide, for example, LiMnO ₂ having a layered structure, the _{Li 1 + a Mn 2-ab} M b M 'c O 4-d (M having a spinel structure Co, Ni, Mg, Cr, Zn , Cu, Y, Al, Ti and Fe, and at least one element selected from the group consisting of Fe, M ′ is a halogen element selected from fluorine, chlorine, bromine and iodine, boron, sulfur, At least one element or two or more elements selected from the group consisting of sodium and calcium, a, b, c and d are 0 ≦ a ≦ 0.33, 0 ≦ b ≦ 0.2, 0 ≦ c ≦ 0. 2, 0 ≦ d ≦ 0.5). In particular, lithium manganese composite oxide having a spinel structure is preferable.

Examples of lithium-containing composite oxides that store and release lithium (excluding lithium manganese composite oxides) include lithium nickel composite oxides (eg, LiNiO ₂ ), lithium cobalt composite oxides (eg, LiCoO ₂ ), and lithium nickel cobalt. Compound oxide {for example, LiNi _1-y-z Co _y T _z O ₂ (T is at least one element selected from the group consisting of Al, Cr and Fe, 0 ≦ y ≦ 0.5, 0 ≦ z ≦ 0.1)}, lithium manganese cobalt composite oxide {for example, LiMn _1-y-Z Co _y T _z O ₂ (T is at least one element selected from the group consisting of Al, Cr and Fe, 0 ≦ y ≦ 0.5,0 ≦ z ≦ 0.1)} , lithium-manganese-nickel composite compound {e.g. _{LiMn x Ni x R 1-2x O 2} (R consists Co, Cr, Al and Fe At least one element more selective, 1/3 ≦ x ≦ 1 /2, for _{example, LiMn 1/3 Ni 1/3 Co 1/3 O} 2, LiMn 1/2 Ni 1/2 O 2}, spinel type lithium-manganese-nickel composite oxide (e.g., _{LiMn 2-y Ni y O 4} ), lithium phosphates having an olivine structure (e.g., LiFePO _4, LiFe like _{1-y Mn y PO 4,} LiCoPO 4) and the like it can.

  In addition, when the amount of lithium in the lithium-containing oxide is x, x varies in the range of 0 ≦ x ≦ 1.2 due to charge / discharge reaction.

  The lithium-containing composite oxide mixed with the lithium-manganese composite oxide is preferably composed of at least one of lithium-cobalt composite oxide, lithium-nickel composite oxide, and lithium-nickel-cobalt-manganese composite oxide. . According to these, the energy density of the positive electrode can be improved. A lithium cobalt composite oxide is particularly preferable, and a positive electrode having high energy density and excellent large current output characteristics when SOC is low can be obtained. In addition, about y and z for which there is no description of a preferable range above, it is preferable that it is the range of 0 or more and 1 or less.

The positive electrode active material may contain various oxides and sulfides. For example, manganese dioxide (MnO ₂ ), iron oxide, copper oxide, nickel oxide, iron sulfate (Fe ₂ (SO ₄ ) ₃ ), vanadium oxide (for example, V ₂ O ₅ ), and the like can be given. In addition, conductive polymer materials such as polyaniline and polypyrrole, disulfide-based polymer materials, organic materials such as sulfur (S) and carbon fluoride, and inorganic materials are also included.

  The specific surface area of the lithium manganese composite oxide is preferably smaller than the specific surface area of other positive electrode active materials. As a result, elution of Mn from the lithium manganese composite oxide can be suppressed, so that Mn in the non-aqueous electrolyte can be suppressed from being deposited on the negative electrode during abuse such as being left at a high temperature or overcharged. An increase in negative electrode resistance can be suppressed.

  The ratio of the lithium manganese composite oxide to the weight of the positive electrode active material is desirably in the range of 75 to 99%. Thereby, a positive electrode with a high energy density is obtained.

  Examples of the conductive agent include acetylene black, ketjen black (trademark), graphite, and coke.

  Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluorine-based rubber.

  The mixing ratio of the positive electrode active material, the conductive agent and the binder is preferably in the range of 73 to 95% by weight of the positive electrode active material, 3 to 20% by weight of the conductive agent, and 2 to 7% by weight of the binder.

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

The average crystal grain size is determined as follows. The structure of the current collector surface is observed with an optical microscope, and the number n of crystal grains existing within 1 mm × 1 mm is determined. Using this n, the average crystal grain area S is determined from S = 1 × 10 ⁶ / n (μm ² ). The average crystal particle diameter d (μm) is calculated from the obtained S value by the following formula (B).

d = 2 (S / π) 1/2 (B)
The average crystal grain size of the aluminum foil and the aluminum alloy foil changes under complicated influences from a plurality of factors such as material structure, impurities, processing conditions, heat treatment history, and annealing conditions. The crystal grain size can be prepared by combining the above factors in the production process of the current collector.

  The thickness of the aluminum foil and the aluminum alloy foil is 20 μm or less, more preferably 15 μm or less. The purity of the aluminum foil is preferably 99% or more. As the aluminum alloy, an alloy containing elements such as magnesium, zinc and silicon is preferable. On the other hand, the content of transition metals such as iron, copper, nickel and chromium is preferably 1% or less.

2) Negative electrode This negative electrode has a negative electrode current collector and a negative electrode active material-containing layer that is supported on one or both surfaces of the current collector and contains a negative electrode active material, a binder, and, if necessary, a conductive agent. For example, the negative electrode is prepared by adding a binder to a powdered negative electrode active material, suspending the binder in a suitable solvent, and applying the suspension to a current collector of a metal foil made of aluminum or an aluminum alloy. It is produced by drying and pressing to form a strip electrode.

As the negative electrode active material, a material in which a charge / discharge reaction occurs at a potential of 1 V or more (preferably 1.1 V or more and 3 V or less) with respect to lithium is used. Here, a method for measuring the reaction potential will be described. A three-electrode cell is produced using a negative electrode active material as a working electrode and metallic lithium as a counter electrode and a reference electrode. This three-electrode cell undergoes lithium insertion / extraction reaction at a current value that is 1/10 of the electric capacity of the working electrode, that is, at a 0.1 C rate. Here, a current value sufficient to discharge the electric capacity of the electrode in one hour is referred to as a 1C rate, and a multiple of the current value is represented as a C rate. The average operating potential in the lithium elimination reaction at this time was defined as the reaction potential of the negative electrode active material. An example of such a negative electrode active material is spinel type lithium titanium composite oxide. Examples of the spinel-type lithium titanium composite oxide include Li _{4 + x} Ti ₅ O ₁₂ (x varies within a range of −1 ≦ x ≦ 3 due to a charge / discharge reaction). A spinel type lithium titanium composite oxide may be used alone, or a plurality of other active materials may be mixed. Examples of the active material to be mixed include lithium compounds that occlude and release lithium.

  Examples of the lithium compound include lithium oxide, lithium sulfide, and lithium nitride. Among these, a metal compound that does not contain lithium in an uncharged state, but also includes a compound that contains lithium when charged.

Such oxides include, for example, titanium-containing metal composite oxides, for example, amorphous tin oxides such as SnB _0.4 P _0.6 O _3.1 , tin silicon oxides such as SnSiO ₃ , silicon oxides such as SiO, for example WO _And tungsten oxide such as ₃ . Of these, titanium-containing metal composite oxides are preferable.

Examples of the titanium-containing metal composite oxide include lithium titanium oxide, and titanium-based oxides that do not contain lithium during oxide synthesis. Examples of lithium titanium oxides other than the spinel-type lithium titanium composite oxide include lithium titanate having a ramsdellite structure. Examples of lithium titanate having a ramsdellite structure include Li _{2 + y} Ti ₃ O ₇ (y varies within a range of −1 ≦ y ≦ 3 due to charge / discharge reaction). Examples of the titanium-based oxide include metal composite oxides containing at least one element selected from the group consisting of TiO ₂ , Ti and P, V, Sn, Cu, Ni, and Fe. TiO ₂ is preferably anatase type and low crystalline having a heat treatment temperature of 300 to 500 ° C. Examples of the metal composite oxide containing at least one element selected from the group consisting of Ti and P, V, Sn, Cu, Ni and Fe include TiO ₂ —P ₂ O ₅ , TiO ₂ —V _2. O ₅ , TiO ₂ —P ₂ O ₅ —SnO ₂ , TiO ₂ —P ₂ O ₅ —MeO (Me is at least one element selected from the group consisting of Cu, Ni and Fe). . This metal composite oxide has a low crystallinity and preferably has a microstructure in which the crystal phase and the amorphous phase coexist or exist alone. With such a microstructure, cycle performance can be greatly improved. Among these, lithium titanium oxide, metal composite oxide containing at least one element selected from the group consisting of Ti and P, V, Sn, Cu, Ni and Fe are preferable.

Examples of the sulfide include titanium sulfide such as TiS ₂ , molybdenum sulfide such as MoS _2, and iron sulfide such as FeS, FeS ₂ , and Li _x FeS ₂ .

Examples of the nitride include lithium cobalt nitride (for example, Li _x Co _y N, 0 <x <4, 0 <y <0.5).

  Examples of the conductive agent include metal powders such as acetylene black, ketjen black, and graphite.

  Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine rubber, and styrene butadiene rubber.

  The compounding ratio of the negative electrode active material, the conductive agent and the binder is preferably in the range of 73 to 98% by weight of the negative electrode active material, 0 to 20% by weight of the conductive agent, and 2 to 7% by weight of the binder.

  The negative electrode current collector is preferably formed from an aluminum foil or an aluminum alloy foil. The negative electrode current collector preferably has an average crystal grain size of 50 μm or less. Thereby, since the intensity | strength of an electrical power collector can be increased greatly, it becomes possible to make a negative electrode high density with a high press pressure, and can increase battery capacity. Moreover, since the dissolution / corrosion deterioration of the negative electrode current collector in the overdischarge cycle under a high temperature environment (40 ° C. or higher) can be prevented, an increase in the negative electrode impedance can be suppressed. Furthermore, output characteristics, quick charge, and charge / discharge cycle characteristics can also be improved. A more preferable range of the average crystal grain size is 30 μm or less, and a further preferable range is 5 μm or less. The hard material is preferably an H material.

  The thickness of the aluminum foil and the aluminum alloy foil is 20 μm or less, more preferably 15 μm or less. The purity of the aluminum foil is preferably 99% or more. As the aluminum alloy, an alloy containing elements such as magnesium, zinc, and silicon is preferable. On the other hand, the content of transition metals such as iron, copper, nickel and chromium is preferably 1% or less.

3) Nonaqueous electrolyte This nonaqueous electrolyte contains a nonaqueous solvent and an electrolyte salt dissolved in the nonaqueous solvent. Further, the non-aqueous solvent may contain a polymer.

Examples of the electrolyte salt include LiPF ₆ , LiBF ₄ , Li (CF ₃ SO ₂ ) ₂ N (bistrifluoromethanesulfonylamide lithium; commonly known as LiTFSI), LiCF ₃ SO ₃ (commonly known as LiTFS), and Li (C ₂ F ₅ SO ₂ ). ₂ N (bis pentafluoroethanesulfonyl amide lithium; called _{LiBETI), LiClO 4, LiAsF 6} , LiSbF 6, bisoxalato Lato lithium borate _{(LiB (C 2 O 4)} 2 ( known as LiBOB)), difluoro (tri-fluoro-2 Examples thereof include lithium salts such as -oxide-2-trifluoro-methylpropionate (2-)-0,0) lithium borate {LiBF ₂ OCOOC (CF ₃ ) ₂ , commonly called LiBF ₂ (HHIB)}. These electrolyte salts may be used alone or in combination of two or more. Particularly preferred are LiPF ₆ and LiBF ₄ .

  Here, the electrolyte salt concentration is preferably in the range of 1M or more and 3M or less. By setting it within this range, excellent performance can be obtained when a high load current is passed.

  The non-aqueous solvent is not particularly limited, but propylene carbonate (PC), ethylene carbonate (EC), 1,2-dimethoxyethane (DME), γ-butyrolactone (GBL), tetrahydrofuran (THF), 2 -Methyltetrahydrofuran (2-MeHF), 1,3-dioxolane, sulfolane, acetonitrile (AN), diethyl carbonate (DEC), dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), dipropyl carbonate (DPC), etc. It is done. These solvents may be used alone or in combination of two or more.

  Moreover, you may add an additive to this nonaqueous electrolyte. Although it does not specifically limit as an additive, Vinylene carbonate (VC), vinylene acetate (VA), vinylene butyrate, vinylene hexanate, vinylene crotonate, catechol carbonate, etc. are mentioned. The concentration of the additive is preferably in the range of 0.1 wt% or more and 3 wt% or less with respect to 100 wt% of the nonaqueous electrolyte. A more preferable range is 0.5 wt% or more and 1 wt% or less.

4) Separator A porous film or non-woven fabric obtained from a polymer such as polyolefin, cellulose, polyethylene terephthalate, or vinylon is used for the insulating separator between the positive electrode and the negative electrode. Here, the material of the separator is selected from one type or a combination of two or more types.

  The present invention can be applied to various forms of nonaqueous electrolyte batteries such as a cylindrical shape, a thin shape, a square shape, and a coin shape. One embodiment of a nonaqueous electrolyte battery is shown in FIGS. As shown in FIG. 1, the electrode group 1 is housed in a rectangular cylindrical metal container 2. The electrode group 1 has a flat shape in which a positive electrode 3 (positive electrode active material-containing layer 3b, positive electrode current collector 3a) and a negative electrode 4 (negative electrode active material-containing layer 4b, negative electrode current collector 4a) are interposed with a separator 5 therebetween. It has a structure wound in a spiral shape. As shown in FIG. 3, the positive electrode 3 has a structure in which a positive electrode active material-containing layer 3b is formed on one side or both sides of a positive electrode current collector 3a. On the other hand, the negative electrode 4 has a structure in which the negative electrode active material-containing layer 4b is formed on one surface or both surfaces of the negative electrode current collector 4a. A nonaqueous electrolyte (not shown) is held in the electrode group 1. As shown in FIG. 2, a plurality of strip-like positive electrode leads 6 are drawn from the end face of the electrode group 1. The positive electrode lead 6 is electrically connected to the end of the positive electrode 3 as shown in FIG. Similarly, as shown in FIG. 1, the strip-like negative electrode lead 7 is electrically connected to the end of the negative electrode 4. Although not shown here, a plurality of negative electrode leads 7 are also drawn from the same end face of the electrode group 1. The plurality of positive electrode leads 6 are electrically connected to the positive electrode conductive tab 8 in a bundled state. The positive electrode lead 6 and the positive electrode conductive tab 8 constitute a positive electrode terminal. The negative electrode lead 7 is connected to the negative electrode conductive tab 9 in a bundled state. The negative electrode lead 7 and the negative electrode conductive tab 9 constitute a negative electrode terminal. The metal sealing plate 10 is fixed to the opening of the metal container 2 by welding or the like. The positive electrode conductive tab 8 and the negative electrode conductive tab 9 are each drawn out from an extraction hole provided in the sealing plate 10. The inner peripheral surface of each extraction hole of the sealing plate 10 is covered with an insulating member 11 in order to avoid a short circuit due to contact with the positive electrode conductive tab 8 and the negative electrode conductive tab 9.

[Example]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Example 1
<Preparation of positive electrode>
LiCoO ₂ (specific surface area 0.9 m ² / g) is used as the positive electrode active material, and 3 wt% of the graphite powder and the entire positive electrode is used as a conductive agent so that the proportion becomes 3 wt% with respect to the entire positive electrode. The slurry was prepared by blending acetylene black in a proportion and PVdF as a binder to 5 wt% with respect to the whole positive electrode and dispersing in n-methylpyrrolidone (NMP) solvent. The obtained slurry was applied on both sides of an aluminum foil having a thickness of 15 μm and dried.

LiMn ₂ O ₄ (specific surface area 0.6 m ² / g) is used as the positive electrode active material on both upper surfaces of this, and graphite powder and a conductive agent are used in a proportion of 3% by weight with respect to the whole positive electrode. Disperse in n-methylpyrrolidone (NMP) solvent by blending acetylene black to a ratio of 3% by weight with respect to the whole positive electrode and PVdF to be 5% by weight with respect to the whole positive electrode as a binder. Then, the slurry prepared was applied and dried. Subsequently, through a pressing process, a positive electrode having an electrode density of 3.1 g / cm ³ was produced. In the obtained positive electrode, LiCoO ₂ is distributed on the current collector side (positive electrode current collector 3a side in FIG. 3), and the electrode surface side closer to the negative electrode than in the positive electrode current collector side (in FIG. 3, the positive electrode active material-containing layer 3b LiMn ₂ O ₄ was distributed on the separator 5 side surface), and the weight ratio of LiCoO ₂ to LiMn ₂ O ₄ was 1: 4.

<Production of negative electrode>
Li ₄ Ti ₅ O ₁₂ (charge / discharge reaction is performed with respect to lithium at a potential of about 1.5 V) is used as the negative electrode active material, graphite is 7% by weight with respect to the whole negative electrode, and PVdF is used as the binder. Was mixed in an N-methylpyrrolidone (NMP) solution so as to be 2% by weight with respect to the whole negative electrode. The obtained slurry was applied to a current collector made of an aluminum foil having a thickness of 15 μm, dried, and pressed to prepare a negative electrode having an electrode density of 2.1 g / cm ³ .

<Preparation of non-aqueous electrolyte>
1M LiPF ₆ and 0.5M LiBF ₄ were mixed in a mixed solvent of PC: DEC = 1: 2 (volume ratio) to obtain a nonaqueous electrolyte.

<Battery assembly>
The positive electrode and the negative electrode were wound through a separator made of polypropylene to produce a flat electrode group. This electrode group is inserted into a metal can made of aluminum, and the opening portion of the metal can is sealed with a cap having a liquid injection hole, and then dried, and the nonaqueous electrolyte is injected, and the liquid injection hole is sealed to have a capacity of 1 Ah. A non-aqueous electrolyte battery was completed.

(Example 1-2)
A battery was produced in the same manner as in Example 1 except that the specific surface area of LiMn ₂ O ₄ was 1.2 m ² / g.

(Examples 2 to 5)
A battery having the same configuration as that described in Example 1 was prepared except that the weight ratio of LiCoO ₂ and LiMn ₂ O ₄ was the value shown in Table 1 below.

(Example 6)
A mixed powder of LiCoO ₂ (specific surface area 0.9 m ² / g) and LiMn ₂ O ₄ (specific surface area 0.6 m ² / g) in a weight ratio of 1: 4 is used as the positive electrode active material, and the positive electrode is used as a conductive agent for this. Acetylene black is used as a binder, and 5% by weight with respect to the whole positive electrode as a binder, so that the ratio is 3% by weight with respect to the whole and 3% by weight of graphite powder. PVdF was blended and dispersed in an n-methylpyrrolidone (NMP) solvent to prepare a slurry. The obtained slurry was applied to both sides of a 15 μm thick aluminum foil and dried. A battery was produced in the same manner as in Example 1 except that the dried positive electrode was subjected to a pressing step to produce a positive electrode having an electrode density of 3.1 g / cm ³ .

(Examples 7 to 10)
A battery having the same configuration as that described in Example 6 was prepared except that the weight ratio of LiCoO ₂ and LiMn ₂ O ₄ was set to the value shown in Table 1 below.

(Example 11)
A mixed powder having a weight ratio of 1: 1 LiCoO ₂ (specific surface area 0.9 m ² / g) and LiMn ₂ O ₄ (specific surface area 0.6 m ² / g) is used as the positive electrode active material, and the positive electrode is used as a conductive agent. Acetylene black is used as a binder, and 5% by weight with respect to the whole positive electrode as a binder, so that the ratio is 3% by weight with respect to the whole and 3% by weight of graphite powder. PVdF was blended and dispersed in an n-methylpyrrolidone (NMP) solvent to prepare a slurry. The obtained slurry was applied to both sides of an aluminum foil having a thickness of 15 μm and dried to form a first layer on both sides of the aluminum foil.

A mixed powder of LiCoO ₂ (specific surface area 0.9 m ² / g) and LiMn ₂ O ₄ (specific surface area 0.6 m ² / g) in a weight ratio of 1: 4 is used as the positive electrode active material, and the positive electrode is used as a conductive agent for this. Acetylene black is used as a binder, and 5% by weight with respect to the whole positive electrode as a binder, so that the ratio is 3% by weight with respect to the whole and 3% by weight of graphite powder. PVdF was blended and dispersed in an n-methylpyrrolidone (NMP) solvent to prepare a slurry. The resulting slurry was applied to the surface of both first layers and allowed to dry. Subsequently, the battery similar to Example 1 was produced except having produced the positive electrode with an electrode density of 3.1 g / cm < ³ > through the press process.

(Example 12)
Li (Ni, Co, Mn) O ₂ {specific surface area is 0.4 m ² / g, Ni: Co: Mn = 1: 1: 1 (atomic ratio)} is used as a positive electrode active material, and as a conductive agent Acetylene black is used as a binder to a proportion of 3% by weight with respect to the whole positive electrode and 5% by weight with respect to the whole positive electrode as a binder. Each of PVdF was blended and dispersed in an n-methylpyrrolidone (NMP) solvent to prepare a slurry. The obtained slurry was applied to both sides of an aluminum foil having a thickness of 15 μm and dried to form a first layer on both sides of the aluminum foil.

LiMn ₂ O ₄ (specific surface area 0.6 m ² / g) is used as the positive electrode active material, and 3 wt% of the graphite powder and the entire positive electrode as a conductive agent so as to have a ratio of 3 wt% with respect to the entire positive electrode. % Of acetylene black and PVdF of 5% by weight with respect to the whole positive electrode as a binder were mixed and dispersed in an n-methylpyrrolidone (NMP) solvent to prepare a slurry. The resulting slurry was applied to the surface of both first layers and allowed to dry. Next, a battery similar to that of Example 1 was produced except that a positive electrode having an electrode density of 2.9 g / cm ³ was produced through a pressing process.

In the obtained positive electrode, Li (Ni, Co, Mn) O ₂ is distributed on the current collector side, LiMn ₂ O ₄ is distributed on the electrode surface side (separator side), and Li (Ni, Co, Mn) O _2. The weight ratio of LiMn ₂ O ₄ was 1: 4.

(Examples 13 and 14)
A battery having the same configuration as that described in Example 12 was prepared except that the weight ratio of Li (Ni, Co, Mn) O ₂ and LiMn ₂ O ₄ was the value shown in Table 2 below. .

(Example 15)
Li (Ni, Co, Mn) O ₂ {specific surface area 0.4 m ² / g, Ni: Co: Mn = 1: 1: 1 (atomic ratio)} and LiMn ₂ O ₄ (specific surface area 0. 0) were used as the positive electrode active material. 6 m ² / g) is a mixed powder having a weight ratio of 1: 4, and a ratio of 3% by weight with respect to the graphite powder and the whole positive electrode is used as a conductive agent. Thus, acetylene black was mixed with PVdF as a binder so as to be 5% by weight with respect to the whole positive electrode, and dispersed in an n-methylpyrrolidone (NMP) solvent to prepare a slurry. The obtained slurry was applied to both sides of a 15 μm thick aluminum foil and dried. A battery was produced in the same manner as in Example 1 except that the dried positive electrode was subjected to a pressing step to produce a positive electrode having an electrode density of 2.9 g / cm ³ .

(Examples 16 and 17)
A battery having the same configuration as that described in Example 15 was prepared except that the weight ratio of Li (Ni, Co, Mn) O ₂ and LiMn ₂ O ₄ was the value shown in Table 2 below. .

(Example 18)
LiNiO ₂ (specific surface area 0.4 m ² / g) is used as the positive electrode active material, and 3 wt% of the graphite powder and the entire positive electrode is used as a conductive agent so that the ratio is 3 wt% with respect to the entire positive electrode. The slurry was prepared by blending acetylene black in a proportion and PVdF as a binder to 5 wt% with respect to the whole positive electrode and dispersing in n-methylpyrrolidone (NMP) solvent. The obtained slurry was applied to both sides of an aluminum foil having a thickness of 15 μm and dried to form a first layer on both sides of the aluminum foil.

LiMn ₂ O ₄ (specific surface area 0.6 m ² / g) is used as the positive electrode active material, and 3 wt% of the graphite powder and the entire positive electrode as a conductive agent so as to have a ratio of 3 wt% with respect to the entire positive electrode. % Of acetylene black and PVdF of 5% by weight with respect to the whole positive electrode as a binder were mixed and dispersed in an n-methylpyrrolidone (NMP) solvent to prepare a slurry. The resulting slurry was applied to the surface of both first layers and allowed to dry. Subsequently, the battery similar to Example 1 was produced except having produced the positive electrode of electrode density 3.0g / cm < ³ > through the press process.

In the obtained positive electrode, LiNiO ₂ was distributed on the current collector side, LiMn ₂ O ₄ was distributed on the electrode surface side (separator side), and the weight ratio of LiNiO ₂ and LiMn ₂ O ₄ was 1: 4.

(Examples 19 and 20)
A battery having the same configuration as that described in Example 18 was prepared except that the weight ratio of LiNiO ₂ and LiMn ₂ O ₄ was the value shown in Table 3 below.

(Example 21)
A mixed powder with a weight ratio of 1: 4 LiNiO ₂ (specific surface area 0.4 m ² / g) and LiMn ₂ O ₄ (specific surface area 0.6 m ² / g) is used as the positive electrode active material, and the positive electrode is used as a conductive agent for this. Acetylene black is used as a binder, and 5% by weight with respect to the whole positive electrode as a binder, so that the ratio is 3% by weight with respect to the whole and 3% by weight of graphite powder. PVdF was blended and dispersed in an n-methylpyrrolidone (NMP) solvent to prepare a slurry. The obtained slurry was applied to both sides of a 15 μm thick aluminum foil and dried. A battery was produced in the same manner as in Example 1 except that the positive electrode having an electrode density of 3.0 g / cm ³ was produced by pressing the dried positive electrode.

(Examples 22 and 23)
A battery having the same configuration as that described in Example 21 was prepared, except that the weight ratio of LiNiO ₂ and LiMn ₂ O ₄ was the value shown in Table 3 below.

(Example 24)
TiO ₂ (charge / discharge reaction is performed at a potential of about 1.7 V with respect to lithium) is used as the negative electrode active material, graphite as a conductive agent is 7% by weight with respect to the whole negative electrode, and PVdF is used as a binder throughout the negative electrode. A slurry was prepared by mixing in an N-methylpyrrolidone (NMP) solution so as to be 2% by weight. A battery similar to that of Example 1 was produced except that the obtained slurry was applied to a current collector made of an aluminum foil having a thickness of 15 μm, dried and pressed to produce a negative electrode having an electrode density of 1.9 g / cm ^3. did.

(Example 25)
Li ₂ Ti ₃ O ₇ (the charge / discharge reaction is performed with respect to lithium at a potential of about 1.4 V) is used as the negative electrode active material, graphite is 7% by weight as the conductive agent, and PVdF is the binder. Was mixed in an N-methylpyrrolidone (NMP) solution so as to be 2% by weight with respect to the whole negative electrode. A battery similar to that of Example 1 was produced, except that the obtained slurry was applied to a current collector made of an aluminum foil having a thickness of 15 μm, dried and pressed to produce a negative electrode having an electrode density of 2.0 g / cm ^3. did.

(Example 26)
A battery was prepared in the same manner as in Example 1 except that 1.5M LiPF ₆ was mixed in a mixed solvent of PC: DEC = 1: 2 (volume ratio) to obtain a nonaqueous electrolyte.

(Example 27)
A battery was prepared in the same manner as in Example 1 except that 2M LiBF ₄ was mixed in a mixed solvent of EC: GBL = 1: 2 (volume ratio) to obtain a nonaqueous electrolyte.

(Example 28)
A battery was prepared in the same manner as in Example 1 except that 2M LiBF ₄ was mixed with a mixed solvent of EC: PC: GBL = 1: 1: 4 (volume ratio) to obtain a nonaqueous electrolyte.

(Example 29)
A battery was prepared in the same manner as in Example 1 except that 1M LiPF ₆ and 0.5M LiBF ₄ were mixed in a mixed solvent of PC: MEC = 1: 2 (volume ratio) to obtain a nonaqueous electrolyte.

(Example 30)
A battery was prepared in the same manner as in Example 1 except that 1M LiPF ₆ and 0.5M LiBF ₄ were mixed in a mixed solvent of EC: MEC = 1: 2 (volume ratio) to obtain a nonaqueous electrolyte.

(Example 31)
A battery was prepared in the same manner as in Example 1 except that 1M LiPF ₆ and 0.5M LiBF ₄ were mixed in a mixed solvent of EC: DEC = 1: 2 (volume ratio) to obtain a nonaqueous electrolyte.

(Example A)
A battery was produced in the same manner as in Example 1 except that Li _1.1 Mn _1.8 Al _0.05 Co _0.05 O ₄ was used as the lithium manganese composite oxide.

(Example B)
A battery was produced in the same manner as in Example 1 except that Li _1.1 Mn _1.8 Al _0.04 Co _0.04 Mg _0.02 O ₄ was used as the lithium manganese composite oxide.

(Example C)
A battery was prepared in the same manner as in Example 1 except that Li _1.1 Mn _1.8 Al _0.1 O ₄ was used as the lithium manganese composite oxide.

(Example D)
A battery was prepared in the same manner as in Example 1 except that Li _1.09 Mn _1.9 Mg _0.01 F _0.05 B _0.005 O ₄ was used as the lithium manganese composite oxide.

(Example E)
A battery was produced in the same manner as in Example 1 except that Li _1.05 Mn _1.85 Al _0.1 F _0.05 S _0.02 O ₄ was used as the lithium manganese composite oxide.

(Example F)
A battery was produced in the same manner as in Example 1 except that Li _1.09 Mn _1.9 Mg _0.01 B _0.005 O ₄ was used as the lithium manganese composite oxide.

(Example G)
A battery was produced in the same manner as in Example 1 except that Li _1.05 Mn _1.85 Al _0.1 B _0.005 O ₄ was used as the lithium manganese composite oxide.

(Comparative Example 1)
LiCoO ₂ (specific surface area 0.9 m ² / g) is used as the positive electrode active material, and 3 wt% of the graphite powder and the entire positive electrode is used as a conductive agent so that the proportion becomes 3 wt% with respect to the entire positive electrode. After preparing acetylene black to a proportion and PVdF as a binder to 5% by weight with respect to the whole positive electrode and dispersing in n-methylpyrrolidone (NMP) solvent to prepare a slurry, A battery was prepared in the same manner as in Example 1 except that a positive electrode having an electrode density of 3.1 g / cm ³ was produced by applying a dried and applied aluminum foil having a thickness of 15 μm through a pressing process.

(Comparative Example 2)
Li (Ni, Co, Mn) O ₂ {specific surface area 0.4 m ² / g, Ni: Co: Mn = 1: 1: 1 (atomic ratio)} is used as the positive electrode active material, and the whole positive electrode is used as a conductive agent. 3% by weight of graphite powder and acetylene black at a rate of 3% by weight with respect to the whole positive electrode, and PVdF as a binder at 5% by weight with respect to the whole positive electrode. Were mixed in n-methylpyrrolidone (NMP) solvent to prepare a slurry, applied to an aluminum foil having a thickness of 15 μm, dried, and subjected to a pressing process to form a positive electrode having an electrode density of 3.1 g / cm ³ . A battery was produced in the same manner as in Example 1 except that was produced.

(Comparative Example 3)
LiNiO ₂ (specific surface area 0.4 m ² / g) is used as the positive electrode active material, and 3 wt% of the graphite powder and the entire positive electrode is used as a conductive agent so that the ratio is 3 wt% with respect to the entire positive electrode. After preparing acetylene black to a proportion and PVdF as a binder to 5% by weight with respect to the whole positive electrode and dispersing in n-methylpyrrolidone (NMP) solvent to prepare a slurry, A battery was prepared in the same manner as in Example 1 except that a positive electrode having an electrode density of 3.1 g / cm ³ was produced by applying a dried and applied aluminum foil having a thickness of 15 μm through a pressing process.

(Comparative Example 4)
LiCoO ₂ (specific surface area 0.9 m ² / g) is used as the positive electrode active material, and 3 wt% of the graphite powder and the entire positive electrode is used as a conductive agent so that the proportion becomes 3 wt% with respect to the entire positive electrode. After preparing acetylene black to a proportion and PVdF as a binder to 5% by weight with respect to the whole positive electrode and dispersing in n-methylpyrrolidone (NMP) solvent to prepare a slurry, A battery was prepared in the same manner as in Example 24 except that a positive electrode having an electrode density of 3.1 g / cm ³ was produced by applying a dried and applied aluminum foil having a thickness of 15 μm to the positive electrode through a pressing process.

(Comparative Example 5)
LiCoO ₂ (specific surface area 0.9 m ² / g) is used as the positive electrode active material, and 3 wt% of the graphite powder and the entire positive electrode is used as a conductive agent so that the proportion becomes 3 wt% with respect to the entire positive electrode. After preparing acetylene black to a proportion and PVdF as a binder to 5% by weight with respect to the whole positive electrode and dispersing in n-methylpyrrolidone (NMP) solvent to prepare a slurry, A battery was fabricated in the same manner as in Example 25 except that a positive electrode having an electrode density of 3.1 g / cm ³ was produced by applying a dried and coated aluminum foil having a thickness of 15 μm through a pressing process.

(Comparative Example 6)
A battery was prepared in the same manner as in Comparative Example 1 except that 1.5M LiPF ₆ was mixed with a mixed solvent of PC: DEC = 1: 2 (volume ratio) to make a nonaqueous electrolyte.

(Comparative Example 7)
A battery was prepared in the same manner as in Comparative Example 1 except that 2M LiBF ₄ was mixed in a mixed solvent of EC: GBL = 1: 2 (volume ratio) to make a nonaqueous electrolyte.

(Comparative Example 8)
A battery was prepared in the same manner as in Comparative Example 1 except that 2M LiBF ₄ was mixed with a mixed solvent of EC: PC: GBL = 1: 1: 4 (volume ratio) to make a nonaqueous electrolyte.

(Comparative Example 9)
A battery was prepared in the same manner as in Comparative Example 1 except that 1M LiPF ₆ and 0.5M LiBF ₄ were mixed in a mixed solvent of PC: MEC = 1: 2 (volume ratio) to obtain a nonaqueous electrolyte.

(Comparative Example 10)
A battery was prepared in the same manner as in Comparative Example 1 except that 1M LiPF ₆ and 0.5M LiBF ₄ were mixed in a mixed solvent of EC: MEC = 1: 2 (volume ratio) to form a nonaqueous electrolyte.

(Comparative Example 11)
A battery was prepared in the same manner as in Comparative Example 1 except that 1M LiPF ₆ and 0.5M LiBF ₄ were mixed into a mixed solvent of EC: DEC = 1: 2 (volume ratio) to obtain a nonaqueous electrolyte.

(Comparative Example 12)
A carbon material (graphite) is used as the negative electrode active material (a charge / discharge reaction is performed with respect to lithium at a potential of about 0.1 V), and PVdF as a binder is N wt. -A slurry was prepared by mixing in methylpyrrolidone (NMP) solution. A battery similar to Comparative Example 1 was produced except that the obtained slurry was applied to a current collector made of an aluminum foil having a thickness of 15 μm, dried and pressed to produce a negative electrode having an electrode density of 1.6 g / cm ^3. did.

(Comparative Example 13)
A battery was prepared in the same manner as in Comparative Example 12 except that 1.5M LiPF ₆ was mixed with a mixed solvent of PC: DEC = 1: 2 (volume ratio) to make a nonaqueous electrolyte.

(Comparative Example 14)
A battery was prepared in the same manner as in Comparative Example 12 except that 2M LiBF ₄ was mixed in a mixed solvent of EC: GBL = 1: 2 (volume ratio) to make a nonaqueous electrolyte.

(Comparative Example 15)
A battery was prepared in the same manner as in Comparative Example 12 except that 2M LiBF ₄ was mixed with a mixed solvent of EC: PC: GBL = 1: 1: 4 (volume ratio) to make a nonaqueous electrolyte.

(Comparative Example 16)
A battery was prepared in the same manner as in Comparative Example 12 except that 1M LiPF ₆ and 0.5M LiBF ₄ were mixed in a mixed solvent of PC: MEC = 1: 2 (volume ratio) to obtain a nonaqueous electrolyte.

(Comparative Example 17)
A battery was prepared in the same manner as in Comparative Example 12 except that 1M LiPF ₆ and 0.5M LiBF ₄ were mixed in a mixed solvent of EC: MEC = 1: 2 (volume ratio) to obtain a nonaqueous electrolyte.

(Comparative Example 18)
A battery was prepared in the same manner as in Comparative Example 12 except that 1M LiPF ₆ and 0.5M LiBF ₄ were mixed in a mixed solvent of EC: DEC = 1: 2 (volume ratio) to make a nonaqueous electrolyte.

<Battery evaluation>
After charging and discharging the completed battery, the battery is brought to a state of SOC 20%, left in a 60 ° C. environment for 12 hours, discharged at room temperature at a discharge rate of 50 C for 10 seconds, and the output value from the battery voltage after 10 seconds. Was calculated (discharge current [A] × battery voltage [V] after 10 seconds of discharge = output value [W]).

In Table 1, by comparing Comparative Example 1 with Examples 1-11, Examples 1-11 were mixed with LiMn ₂ O ₄ to LiCoO ₂ is Comparative Example 1 using only LiCoO ₂ as the positive electrode active material It can be seen that the output characteristics at low SOC are superior. Further, by comparing Examples 1 to 5, Examples 1, 2, 4, and 5 in which the lithium manganese composite oxide is distributed more on the surface side than on the current collector side are excellent in output characteristics at low SOC. You can see that Furthermore, by comparing Example 1 and Example 1-2, it can be seen that Example 1 in which the specific surface area of LiMn ₂ O ₄ is smaller than LiCoO ₂ is superior in output characteristics.

In Table 2, by comparing Examples 12 to 17 and Comparative Example 2, Examples 12 to 17 in which LiMn ₂ O ₄ is mixed with Li (Ni, Co, Mn) O ₂ are Li (Ni, Co, Mn) O ₂ as the positive electrode active material. It can be seen that the output characteristics at low SOC are improved as compared with Comparative Example 2 using only Ni, Co, Mn) O ₂ . A comparison of Examples 12 to 17 shows that Examples 12 and 13 in which the lithium manganese composite oxide is distributed more on the surface side than on the current collector side are excellent in output characteristics at low SOC.

In Table 3, by comparing Comparative Example 3 Example 18 to 23, Examples 18 to 23 were mixed LiMn ₂ O ₄ in LiNiO ₂ is Comparative Example 3 using only LiNiO ₂ as a positive electrode active material In comparison, it can be seen that the output characteristics at low SOC are improved. By comparison with Examples 18 to 23, Examples 18 and 19 in which the lithium manganese composite oxide is distributed more on the surface side than on the current collector side are excellent in output characteristics at low SOC.

In Table 4, by comparing Comparative Example 4 Example 24, it can be seen that the output characteristics in the low SOC than LiCoO ₂ alone by mixing LiMn ₂ O ₄ to LiCoO ₂ even in TiO ₂ anode is improved.

In Table 5, by comparing Comparative Example 5 and Example 25, the output characteristics in the low SOC than LiCoO ₂ alone by mixing LiMn ₂ O ₄ is improved to LiCoO ₂ in Li ₂ Ti ₃ O ₇ negative I understand that.

In Table 6, by comparing Examples 26 to 31 and Comparative Examples 6 to 11, it can be seen that the effects of the present invention can be obtained even if the composition of the nonaqueous electrolyte is changed. When the negative electrode carbon material is used than Comparative Examples 12 to 18, the increase in impedance due to the precipitation of manganese is large, and in Comparative Examples 12 and 18 using the nonaqueous electrolyte containing LiPF ₆ , LiBF ₄ and DEC, manganese elution is particularly large. I understand.

The results in Table 7, when using _{Li 1 + a Mn 2-ab} M b M 'c O 4-d having a spinel structure as a lithium-manganese composite oxide as in Example A-G, in the low SOC It was confirmed that the effect of improving the output characteristics was obtained.

  The specific surface area of the positive electrode active material used in the above examples was calculated by the BET method by preparing an adsorption isotherm using a gas adsorption apparatus manufactured by Nippon Bell.

In addition, the distribution of LiMn ₂ O ₄ in the positive electrode used in the above examples was obtained by measuring the atomic ratio in the cross section. That is, the positive electrode was taken out from the battery and washed with a methyl ethyl carbonate solvent to remove the non-aqueous electrolyte attached to the positive electrode to prepare a sample. The ratio (for example, Mn / Co ratio) of Mn and other transition metal elements in the depth direction of the sample was measured using a Rigaku glow discharge emission spectrometer.

  The weight ratio of the active material in the positive electrode used in the above examples is measured by the method described below. The non-aqueous electrolyte attached to the positive electrode was removed by taking out the positive electrode from the battery and washing with a methyl ethyl carbonate solvent. A sample was prepared by dissolving the active material in the positive electrode after washing in hydrochloric acid. The ratio of Mn to other transition metal elements in the sample (for example, Mn / Co ratio) was measured using an ICP emission analyzer manufactured by Shimadzu Corporation.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  Hereinafter, embodiments of the invention of the original application are appended.

  [1] A positive electrode including a positive electrode active material-containing layer containing a positive electrode active material containing a lithium manganese composite oxide, a positive electrode current collector on which the positive electrode active material-containing layer is formed, and at least 1 V relative to lithium A non-aqueous electrolyte battery comprising: a negative electrode including a negative electrode active material that performs a charge / discharge reaction at a potential; and a non-aqueous electrolyte.

  [2] The positive electrode includes at least two lithium-containing composite oxides that occlude and release lithium as the positive electrode active material, includes a lithium manganese composite oxide as the positive electrode active material, and more than the positive electrode current collector side. The nonaqueous electrolyte battery according to [1], wherein a large amount of the lithium manganese composite oxide is distributed on the surface side close to the negative electrode.

  [3] The nonaqueous electrolyte battery according to any one of [1] to [2], wherein the lithium manganese composite oxide is spinel type lithium manganate.

  [4] The non-aqueous electrolyte battery according to [1] to [3], wherein the negative electrode active material is a spinel type lithium titanium composite oxide.

  [5] The positive electrode active material further includes at least one other composite oxide of lithium cobalt composite oxide, lithium nickel composite oxide, and lithium nickel cobalt manganese composite oxide. The nonaqueous electrolyte battery according to 1] to [4].

  [6] The nonaqueous electrolyte battery according to [5], wherein a specific surface area of the lithium manganese composite oxide is smaller than a specific surface area of the other composite oxide.

  [7] The nonaqueous electrolyte battery according to [1] to [6], wherein a ratio of the lithium manganese composite oxide to the weight of the positive electrode active material is in a range of 75 to 99%.

[8] The nonaqueous electrolyte battery according to [1] to [7], wherein the nonaqueous electrolyte contains LiPF ₆ , LiBF _4, and a solvent containing diethyl carbonate.

[9] The nonaqueous electrolyte battery according to [8], wherein a molar concentration of LiPF ₆ in the nonaqueous electrolyte is larger than a molar concentration of LiBF ₄ .

  DESCRIPTION OF SYMBOLS 1 ... Electrode group, 2 ... Container, 3 ... Positive electrode, 3a ... Positive electrode collector, 3b ... Positive electrode active material content layer, 4 ... Negative electrode, 4a ... Negative electrode current collector, 4b ... Negative electrode active material content layer, 5 ... Separator , 6 ... positive electrode lead, 7 ... negative electrode lead, 8 ... positive electrode conductive tab, 9 ... negative electrode conductive tab, 10 ... sealing plate, 11 ... insulating member.

Claims (6)

A positive electrode including a positive electrode active material-containing layer containing a positive electrode active material containing a lithium manganese composite oxide; and a positive electrode current collector on which the positive electrode active material-containing layer is formed;
A negative electrode including a negative electrode active material that performs a charge / discharge reaction at a potential of 1 V or more with respect to lithium;
A solvent containing diethyl carbonate; and a nonaqueous electrolyte containing LiPF ₆ and LiBF ₄ dissolved in the solvent, wherein the molar concentration of LiPF ₆ is larger than the molar concentration of LiBF _4. Non-aqueous electrolyte battery characterized.   2. The nonaqueous electrolyte battery according to claim 1, wherein the lithium manganese composite oxide is spinel type lithium manganate.   The non-aqueous electrolyte battery according to claim 1, wherein the negative electrode active material is a spinel type lithium titanium composite oxide.   The positive electrode active material further includes at least one other composite oxide of lithium cobalt composite oxide, lithium nickel composite oxide, and lithium nickel cobalt manganese composite oxide. 4. The nonaqueous electrolyte battery according to any one of 3 above.   The nonaqueous electrolyte battery according to claim 4, wherein a specific surface area of the lithium manganese composite oxide is smaller than a specific surface area of the other composite oxide.   6. The nonaqueous electrolyte battery according to claim 1, wherein a ratio of the lithium manganese composite oxide to the weight of the positive electrode active material is in a range of 75 to 99%.

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