JP2013055006A - Negative electrode for nonaqueous electrolyte battery, nonaqueous electrolyte battery, and battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a nonaqueous electrolyte battery excellent in rate characteristics and capable of being suppressed in decomposition of a nonaqueous electrolyte; a negative electrode used for a nonaqueous electrolyte battery; and a battery pack including a nonaqueous electrolyte battery.SOLUTION: According to an embodiment of the present invention, there is provided a negative electrode for a nonaqueous electrolyte battery, including a negative electrode active material 1 and a conductive agent. The negative electrode active material 1 has a lithium absorption/desorption potential of 1 V vs Li/Lior more and 3 V vs Li/Lior less. The conductive agent includes: a conductive particle 2; and particles 3 of at least one metal selected from the group consisting of Cu, Ag, Au, Pd, In, Zn, Sn, Pb, Pt and Cd or an alloy thereof, the particles 3 being supported on a surface of the conductive particle 2. An average particle size of the particles 3 is 2 nm or more and 100 nm or less.

Description

  Embodiments described herein relate generally to a negative electrode for a nonaqueous electrolyte battery, a nonaqueous electrolyte battery, and a battery pack.

  Nonaqueous electrolyte secondary batteries that are charged and discharged by moving lithium ions between a negative electrode and a positive electrode are attracting attention as high-energy density batteries. Until now, nonaqueous electrolyte secondary batteries have been used as power sources for small electronic devices such as mobile phones and digital cameras. Recently, in addition to higher capacity and higher energy of batteries, improvements such as longer life and higher safety have been progressed, and demand for household storage batteries and power sources for electric vehicles is increasing. In particular, non-aqueous electrolyte secondary batteries for in-vehicle power supplies are required to have both high safety and long life characteristics in addition to large current characteristics.

  A nonaqueous electrolyte secondary battery generally includes a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, a separator, a nonaqueous electrolyte, and an exterior material. As the positive electrode active material, for example, a lithium transition metal composite oxide is used, and as the negative electrode active material, for example, a carbonaceous material is used. Generally, Co, Mn, Ni, Fe, or the like is used as a transition metal component in the lithium transition metal composite oxide.

  In recent years, attention has been focused on lithium metal composite oxides in which the lithium occlusion / release potential is more noble than carbonaceous materials as negative electrode active materials that are replaced by carbonaceous materials. Among lithium metal composite oxides, lithium titanium oxide having a spinel structure has a small volume change during charge and discharge, and is excellent in rapid charge and safety.

Lithium-titanium oxide, 1V (vs.Li/Li ⁺⁾ to absorb lithium in more noble potential, 1V (vs.Li/Li ⁺⁾ active material for lithium absorbing and desorbing at lower potential than the ( For example, a stable reduction film cannot be formed on the surface of the active material at the time of the first charge, like a carbonaceous material. Since the reduction coating has lithium ion conductivity, the decomposition of the electrolytic solution is suppressed without inhibiting the reaction as a battery. If a stable film is not formed, the decomposition reaction of the electrolytic solution will continue.

  The decomposition of the electrolytic solution causes deterioration of the negative electrode active material, deterioration of the electrolytic solution characteristics, and battery swelling due to gas generation. In particular, battery swelling not only causes significant deterioration in battery performance, but also reduces safety such as leakage of electrolyte and battery rupture. In particular, since the electrolytic solution is likely to be decomposed in a high-temperature environment, there is a possibility that the deterioration of characteristics may be noticeable in applications that are likely to become high temperature, such as an in-vehicle power supply.

  In order to suppress the decomposition reaction of the nonaqueous electrolyte, (a) the surface of the conductive particles is coated with a metal oxide, or (b) a part of the surface of the active material is coated with a metal oxide, a metal, or an alloy thereof. Has been done. However, according to (a), since the surface of the conductive particles is coated with a metal oxide having low electrical conductivity, the current collecting property of the conductive particles is lowered, and the rate characteristics may be impaired. Further, according to (b), the coated portion does not have Li ion conductivity, unlike the coating produced by reductive decomposition. For this reason, the covered portion cannot contribute to the insertion / desorption of Li ions during charge / discharge, and the substantial reaction area is reduced, which may impair the rate characteristics.

JP 2007-311057 A JP 2009-245929 A JP 2010-199063 A JP 2011-90794 A

  Problems to be solved by the present invention include a non-aqueous electrolyte battery that has excellent rate characteristics and can suppress decomposition of the non-aqueous electrolyte, a negative electrode used in the non-aqueous electrolyte battery, and a non-aqueous electrolyte battery. And providing a battery pack.

According to the embodiment, a negative electrode for a nonaqueous electrolyte battery including a negative electrode active material and a conductive agent is provided. The negative electrode active material has a lithium insertion / release potential of 1 V vs Li / Li ⁺ or more and 3 V vs Li / Li ⁺ or less. The conductive agent is supported on the surface of the conductive particles and the conductive particles, and is at least one selected from the group consisting of Cu, Ag, Au, Pd, In, Zn, Sn, Pb, Pt, and Cd. Metal or alloy particles. The average particle diameter of the particles is 2 nm or more and 100 nm or less.

The schematic diagram of the fine structure of the negative electrode which concerns on 1st Embodiment. Sectional drawing of the nonaqueous electrolyte battery which concerns on 2nd Embodiment. The expanded sectional view which shows the A section of the nonaqueous electrolyte battery of FIG. The disassembled perspective view of the battery pack which concerns on 3rd Embodiment. The block diagram which shows the electric circuit of the battery pack of FIG.

  Hereinafter, embodiments will be described with reference to the drawings.

(First embodiment)
According to the first embodiment, a negative electrode for a nonaqueous electrolyte battery including a negative electrode current collector and a negative electrode material layer (negative electrode active material-containing layer) formed on the negative electrode current collector is provided. The negative electrode material layer is formed on one side or both sides of the negative electrode current collector and includes a negative electrode active material and a conductive agent. The negative electrode active material has a lithium insertion / release potential of 1 V vs Li / Li ⁺ or more and 3 V vs Li / Li ⁺ or less. The conductive agent is supported on the surface of the conductive particles and the conductive particles, and is at least one selected from the group consisting of Cu, Ag, Au, Pd, In, Zn, Sn, Pb, Pt, and Cd. Metal or alloy particles. The average particle diameter of the particles is 2 nm or more and 100 nm or less.

In a negative electrode active material having a lithium occlusion / release potential of 1 V vs Li / Li ⁺ or more and 3 V vs Li / Li ⁺ or less, an effect of promoting film formation on the negative electrode active material due to the reduction catalytic action of the conductive agent can be obtained. In order to improve the stability and lithium ion conductivity of the coating, it is more preferable that the lithium occlusion / release potential be 1 V vs Li / Li ⁺ or more and 2.5 V vs Li / Li ⁺ or less.

The negative electrode active material having a lithium storage / release potential of 1 V vs Li / Li ⁺ or more and 3 V vs Li / Li ⁺ or less is preferably a titanium-containing metal oxide. A titanium-containing metal oxide having a lithium insertion / release potential of 1 V vs Li / Li ⁺ or more and 3 V vs Li / Li ⁺ or less is, for example, TiO ₂ (eg, bronze type, anatase type, rutile type or brookite type TiO ₂ ). Such titanium-based oxides include, for example, lithium titanium oxide having a spinel structure, a ramsdellite structure, or the like, or a lithium titanium composite oxide in which some of the constituent elements of the lithium titanium oxide are substituted with different elements. Examples of the lithium titanium oxide having a spinel structure include Li _{4 + x} Ti ₅ O ₁₂ (0 ≦ x ≦ 3). The lithium titanium oxide having a ramsdellite structure includes, for example, Li _{2 + y} Ti ₃ O ₇ (0 ≦ y ≦ 3). Examples of the titanium-based oxide include a titanium-containing metal composite oxide containing Ti and at least one element selected from the group consisting of P, V, Sn, Cu, Ni, Fe and Co in addition to TiO _2. Can do.

The negative electrode active material is preferably lithium titanate having a spinel structure from the viewpoint of cycle life. Li _{4 + x} Ti ₅ O ₁₂ (0 ≦ x ≦ 3) having a spinel structure is excellent in cycle characteristics and safety, but has a large amount of gas generated by high-temperature storage. According to the first embodiment, since the amount of gas generation can be suppressed, the characteristics excellent in cycle characteristics and safety can be fully utilized. Therefore, Li _{4 + x} Ti ₅ O ₁₂ (0 ≦ x ≦ 3) having a spinel structure is preferable.

The negative electrode active material preferably has an average particle size of 1 μm or less and a specific surface area in the range of 5 to 50 m ² / g according to the BET method by N ₂ adsorption. The negative electrode active material having such an average particle diameter and specific surface area can increase the utilization rate, and can take out a substantially high capacity. Incidentally, BET specific surface area by N ₂ gas adsorption using the Micromeritics Tex ASPA-2010, for example, Shimadzu Corporation, the adsorbed gas can be measured using N _2.

  The conductive particles play a role of assisting electrical conductivity between the active materials and forming a reaction field of the supported catalyst. Therefore, the conductive particles are required to have high electrical conductivity and are not particularly limited, but include graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black and ketjen black, carbon nanotubes and carbon nanofibers. At least one carbon material particle selected from the group consisting of vapor grown carbon fibers is preferred. On the other hand, diamond-like carbon, glassy carbon, conductive polymer, and the like are not preferable because their electrical conductivity is lower than that of conductive particles and the cost is high.

  Although the particle diameter of electroconductive particle is not specifically limited, It is preferable that an average particle diameter is 0.01 micrometer or more and 5 micrometers or less. When the particle diameter of the conductive particles is within the above range, the surface of the conductive particles can be supported in the form of particles by the metal or alloy, and the effect can be sufficiently exhibited. The average particle diameter is measured by the following method. The diameter of the conductive particles is obtained by TEM observation, and an average value of an arbitrary number is set as the average particle diameter.

The metal particles supported on the surface of the conductive particles are composed of one kind of metal particles selected from the group consisting of Cu, Ag, Au, Pd, In, Zn, Sn, Pb, Pt and Cd. However, it may be composed of two or more kinds of metal particles. The alloy particles carried on the surface of the conductive particles are made of an alloy of at least one element selected from the group consisting of Cu, Ag, Au, Pd, In, Zn, Sn, Pb, Pt and Cd. Particles. The conductive particles may carry only metal particles, may carry only alloy particles, or may carry both metal particles and alloy particles. Cu, Ag, Au, Pd, In, Zn, Sn, Pb, Pt and Cd function as a reduction catalyst even in a non-aqueous solvent. Impurities such as moisture and CO ₂ and non-aqueous electrolytes are adsorbed on the surface of metal or alloy particles (hereinafter referred to as catalyst particles) supported on the surface of the conductive particles, and the activation energy related to the transfer of electrons is It is thought to decrease. Therefore, even at a noble potential such as 1 V (vs. Li ^/ Li ⁺ ), the reduction reaction with stable film formation proceeds sufficiently in the negative electrode active material, and subsequent side reactions can be suppressed. it is conceivable that. At this time, the functional groups on the active material surface and the surface of the conductive particles and the impurities mixed in during battery production change into a stable film due to the reduction reaction, so that the influence of impurities brought into the battery can be reduced. it can. Preferred element types are Cu, Ag, and Au.

  The metal particles and the alloy particles exhibit catalytic activity on the surfaces thereof. Therefore, it is preferable that the particles are dispersed and supported on the surfaces of the conductive particles. Formation of a film on the active material particles at the time of initial charge proceeds in that the three phases of the catalyst particles, the active material surface, and the electrolytic solution are in contact. Therefore, it is desirable that the catalyst particles are supported on the surface of the conductive particles with a gap. Thereby, since electrolyte solution penetrate | invades in the clearance gap between the catalyst particles on the surface of electroconductive particle, the contact area with the electrolyte solution of a electrically conductive agent can be raised. That is, it is not preferable that the catalyst particles cover the entire surface of the conductive particles in the form of a film because the number of contact points with the electrolytic solution is reduced and the formation of the film is difficult to proceed.

  By supporting the catalyst particles so as to cover a part of the surface of the conductive particles, the decomposition reaction of the nonaqueous electrolyte can be suppressed without impairing the rate characteristics. It is desirable that the catalyst particles cover 10% or more, more preferably 30% or more, with respect to the surface of the conductive particles. On the other hand, if 100% (the entire surface) is covered, the catalytic activity decreases due to a decrease in specific surface area. In addition, a three-phase interface between the electrolytic solution and the active material is not formed, and a stable film cannot be formed. The coverage of the conductive particles is measured by the following method. The areas of the catalyst particle-supporting conductive particles and the supported catalyst particles were determined by TEM observation. The area of the catalyst particle-supporting conductive particles was calculated on the assumption that there were no catalyst particles. The percentage of the area of the supported portion with respect to the conductive particles was calculated from the following formula, and was defined as the coverage X (%).

X = (S ₁ / S ₂ ) × 100
However, S ₁ is the area of the catalyst particles, and S ₂ is the area of the conductive particles assuming that the catalyst particles are not supported.

  The average particle diameter of the catalyst particles is preferably 2 nm or more and 100 nm or less. Since the specific surface area is increased and the catalytic activity is increased by reducing the particle diameter, a particle diameter of 100 nm or less is preferable. However, if the average particle diameter is less than 2 nm, the catalyst particles are buried in the supported particles, resulting in insufficient contact, and the production becomes very difficult. By making the average particle diameter 2 nm or more, the contact area between the support particles and the active material particles can be increased, and the production of the conductive agent can be facilitated. A more preferable range of the average particle diameter is 2 nm or more and 20 nm or less. The average particle diameter of the catalyst particles is measured by the following method. The diameter of the catalyst particles supported on the conductive particles is obtained by TEM observation, and an average value of an arbitrary number is set as the average particle diameter.

  When obtaining the average particle diameter, coverage, and average particle diameter of the catalyst particles, the negative electrode is first removed from the battery by the following method.

  The exterior of the battery is disassembled in an inert atmosphere environment such as a glove box, and a part of the negative electrode is taken out from the inside of the battery. Next, the taken-out negative electrode is vacuum-dried, and the electrolyte solution in a negative electrode is removed. Note that the supporting salt may or may not be removed by washing with an electrolyte solvent such as dimethyl carbonate before vacuum drying. After vacuum drying, the negative electrode is processed into a sample piece having a shape as required and subjected to TEM observation.

  Next, elemental analysis such as EDX is performed during TEM observation of the negative electrode, the conductive particles in the electrode are specified, and the average particle diameter, coverage, and average particle diameter of the catalyst particles are measured.

  The catalyst particles are supported on the surface of the conductive particles by a wet coating method or a dry coating method. Examples of the wet coating method include a method of dispersing conductive particles in a metal ion solution and depositing with a reducing agent, a plasma irradiation, a hydrothermal method, an electrolytic plating method, an electroless plating method, and the like. Examples of the dry coating method include a CVD method and a vapor deposition method. In the case of the wet coating method, the average particle diameter of the catalyst particles can be adjusted by changing the type of the reducing agent for supporting the catalyst particles on the conductive particles. In the case of the wet coating method, the average particle diameter of the catalyst particles can be adjusted by increasing the heat treatment temperature after loading and aggregating the catalyst particles.

  In order to uniformly form the catalyst particles on the surface of the conductive particles, it is preferable to employ the following method. After introducing and dispersing conductive particles in a solution containing at least one element selected from the group consisting of Cu, Ag, Au, Pd, In, Zn, Sn, Pb, Pt and Cd, reduction is performed. An agent is introduced and heated while stirring to deposit on the surface of the conductive particles. After drying, metal or alloy particles are deposited by firing, for example, at 50 to 500 ° C. for several minutes to several hours in a reducing atmosphere. The solution can be adjusted, for example, by dissolving a chloride, sulfide, nitrate, or the like containing at least one selected from the group of elements in a solvent such as water or ethanol. According to this method, fine particles of metal or alloy can be supported in a state of being dispersed almost uniformly on the surface of the conductive particles.

  The coverage can be adjusted by changing the average particle diameter and the loading amount of the catalyst particles. In addition, since the frequency of supporting the conductive particles as the carrier varies depending on the type of the catalyst particles, even if the catalyst particles have approximately the same average particle diameter, the coating location is different, resulting in a change in the coverage.

  The negative electrode material layer can contain a binder. The binder is blended to fill the gap between the dispersed negative electrode active materials, and binds the active material and the conductive agent. Examples of the binder include polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF).

  In the negative electrode material layer, the contents of the active material, the conductive agent and the binder are 70 to 96 parts by weight of the active material, 2 to 28 parts by weight of the conductive agent, and 2 parts by weight of the binder, respectively. The amount is preferably 28 parts by weight or less.

  By setting the amount of the conductive agent to 2 parts by weight or more, the current collecting performance of the negative electrode material layer can be improved, and excellent large current characteristics can be obtained in the nonaqueous electrolyte battery. Further, by setting the amount of the binder to 2 parts by weight or more, the binding property between the negative electrode material layer and the negative electrode current collector can be improved, and excellent cycle characteristics can be obtained. On the other hand, from the viewpoint of increasing the capacity, the negative electrode conductive agent and the binder are each preferably 28 parts by weight or less.

  As the current collector, a material that is electrochemically stable at the lithium insertion and extraction potential of the negative electrode active material is used. The current collector is preferably made of copper, nickel, stainless steel or aluminum, or an aluminum alloy containing one or more elements selected from Mg, Ti, Zn, Mn, Fe, Cu and Si. The thickness of the current collector is preferably 5 to 20 μm. A current collector having such a thickness can balance the strength and weight reduction of the negative electrode.

  For example, a negative electrode active material, a conductive agent, and a binder are suspended in a commonly used solvent to prepare a slurry, and the prepared slurry is applied to a current collector and then dried to form a negative electrode material layer. Then, it is manufactured by applying a press. Or you may produce by forming an active material, a electrically conductive agent, and a binder into a pellet form, making it a negative electrode material layer, and forming this on a collector.

  In FIG. 1, the schematic diagram of the fine structure of the negative electrode which concerns on 1st Embodiment is shown. As shown in FIG. 1, the secondary particles 1 of the negative electrode active material are in contact with the fibrous conductive particles 2. Furthermore, at least one metal or alloy particle 3 selected from the group consisting of Cu, Ag, Au, Pd, In, Zn, Sn, Pb, Pt and Cd is formed on a part of the surface of the conductive particle 2. It is supported.

According to the first embodiment, since the metal or alloy particles are supported on the surface of the conductive particles, a stable coating is formed on the surface of the negative electrode active material during the initial charge due to the reduction catalytic action of the metal or alloy. can do. By carrying the metal or alloy particles on the surface of the conductive particles, the CO ₂ reduction reaction proceeds even at a potential of about 1.5 V (vs. Li ^/ Li ⁺ ). Therefore, even if it is a negative electrode active material having a lithium insertion / release reaction at a noble potential of 1 V (vs. Li / Li ⁺ ) or more, a stable film can be formed at the first charge / discharge, and side reactions are suppressed. It is thought that an effect is acquired. Since the film formed on the surface of the negative electrode active material has lithium ion conductivity, it is possible to effectively suppress decomposition of the electrolyte without impairing battery characteristics such as rate characteristics. Therefore, the nonaqueous electrolyte battery including such a negative electrode is excellent in cycle stability, rate characteristics, charge / discharge efficiency, and gas generation resistance.

(Second Embodiment)
According to the second embodiment, the exterior member, the negative electrode according to the first embodiment housed in the exterior member, the positive electrode housed in the exterior member, the positive electrode and the negative electrode housed in the exterior member A non-aqueous electrolyte battery is provided that includes a separator disposed between and a non-aqueous electrolyte housed in an exterior member.

  Hereinafter, the negative electrode, the positive electrode, the nonaqueous electrolyte, the separator, and the exterior member will be described in detail.

1) Negative electrode The negative electrode according to the first embodiment is used for the negative electrode.

2) Positive electrode The positive electrode includes a positive electrode current collector and a positive electrode material layer (positive electrode active material-containing layer). The positive electrode material layer is formed on one side or both sides of the current collector, and includes an active material, and optionally a conductive agent and a binder.

As the active material, for example, an oxide, a sulfide, or a polymer can be used. Examples of oxides and sulfides include manganese dioxide (MnO ₂ ), iron oxide, copper oxide, nickel oxide, lithium manganese complex oxide (eg, Li _x Mn ₂ O ₄ or Li _x ) capable of occluding lithium. MnO ₂ ), lithium nickel composite oxide (eg, Li _x NiO ₂ ), lithium cobalt composite oxide (eg, Li _x CoO ₂ ), lithium nickel cobalt composite oxide (eg, LiNi _1-y Co _y O ₂ ), lithium manganese cobalt composite oxide (e.g., _{Li x Mn y Co 1-y} O 2), lithium manganese nickel complex oxide having a spinel structure (e.g., _{Li x Mn 2-y Ni y} O 4), lithium phosphates having an olivine structure (e.g. _{Li x FePO 4, Li x Fe} 1-y Mn y PO 4, Li x CoPO 4), iron sulfate _{[Fe 2 (SO 4) 3} ], vanadium Oxide (for example, V ₂ O ₅ ) and lithium nickel cobalt manganese composite oxide. Here, 0 <x ≦ 1 and 0 <y ≦ 1. As the active material, these compounds may be used alone, or a plurality of compounds may be used in combination.

  Examples of the polymer include conductive polymer materials such as polyaniline and polypyrrole, or disulfide-based polymer materials.

  Also, sulfur (S) or carbon fluoride can be used as an active material.

Examples of a more preferable active material include a lithium manganese composite oxide (eg, Li _x Mn ₂ O ₄ ), a lithium nickel composite oxide (eg, Li _x NiO ₂ ), and a lithium cobalt composite oxide (eg, Li _x ) having a high positive electrode voltage. CoO ₂ ), lithium nickel cobalt composite oxide (eg, LiNi _1-y Co _y O ₂ ), lithium manganese nickel composite oxide having a spinel structure (eg, Li _x Mn _{2 -y} Ni _y O ₄ ), lithium manganese cobalt composite oxides (e.g., _{Li x Mn y Co 1-y} O 2), lithium iron phosphate (e.g. Li _x FePO _4), and includes a lithium-nickel-cobalt-manganese composite oxide. Here, 0 <x ≦ 1 and 0 <y ≦ 1.

When normal temperature molten salt is used as the non-aqueous electrolyte of the battery, examples of preferable active materials include lithium iron phosphate, Li _x VPO ₄ F (0 ≦ x ≦ 1), lithium manganese composite oxide, lithium nickel composite oxide And lithium nickel cobalt composite oxide. Since these compounds have low reactivity with room temperature molten salts, cycle characteristics can be improved.

The specific surface area of the active material is preferably 0.1 m ² / g or more and 10 m ² / g or less. The positive electrode active material having a specific surface area of 0.1 m ² / g or more can sufficiently ensure the occlusion / release sites of lithium ions. The positive electrode active material having a specific surface area of 10 m ² / g or less is easy to handle in industrial production and can ensure good charge / discharge cycle performance.

  The binder binds the active material and the current collector. Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluorine-based rubber.

  The conductive agent is blended as necessary in order to enhance the current collecting performance and suppress the contact resistance between the active material and the current collector. Examples of the conductive agent include carbonaceous materials such as acetylene black, carbon black, and graphite.

  In the positive electrode material layer, the active material and the binder are preferably blended in a proportion of 80 parts by weight or more and 98 parts by weight or less, and 2 parts by weight or more and 20 parts by weight or less, respectively.

  Sufficient electrode strength can be obtained by setting the binder to an amount of 2 parts by weight or more. Moreover, the compounding quantity of the insulator of an electrode can be reduced by making it 20 parts weight or less, and internal resistance can be reduced.

  When a conductive agent is added, the active material, the binder, and the conductive agent are blended in a proportion of 77 parts by weight to 95 parts by weight, 2 parts by weight to 20 parts by weight, and 3 parts by weight to 15 parts by weight, respectively. It is preferable to do. The conductive agent can exert the above-described effects by setting the amount to 3 parts by weight or more. Moreover, by making it 15 parts by weight or less, decomposition of the nonaqueous electrolyte on the surface of the positive electrode conductive agent under high temperature storage can be reduced.

  The current collector is preferably an aluminum foil or an aluminum alloy foil containing one or more elements selected from Mg, Ti, Zn, Ni, Cr, Mn, Fe, Cu, and Si.

  The thickness of the aluminum foil or aluminum alloy foil is desirably 5 μm or more and 20 μm or less, more preferably 15 μm or less. The purity of the aluminum foil is preferably 99 parts by weight or more. The content of transition metals such as iron, copper, nickel and chromium contained in the aluminum foil or aluminum alloy foil is preferably 1 part by weight or less.

  The positive electrode material is prepared by, for example, preparing a slurry by suspending an active material, a binder, and a conductive agent blended as necessary in a suitable solvent, applying the slurry to the positive electrode current collector, and then drying the positive electrode material. It is produced by forming a layer and then pressing it. The positive electrode may also be produced by forming an active material, a binder, and a conductive agent blended as necessary into a pellet shape to form a positive electrode material layer, and forming this on a current collector.

3) Nonaqueous electrolyte The nonaqueous electrolyte may be, for example, a liquid nonaqueous electrolyte prepared by dissolving an electrolyte in an organic solvent, or a gelled nonaqueous electrolyte obtained by combining a liquid electrolyte and a polymer material. .

  The liquid non-aqueous electrolyte is preferably dissolved in an organic solvent at a concentration of 0.5 mol / L or more and 2.5 mol / L or less.

Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroarsenide (LiAsF ₆ ), trifluorometa Lithium salts such as lithium sulfonate (LiCF ₃ SO ₃ ) and lithium bistrifluoromethylsulfonylimide [LiN (CF ₃ SO ₂ ) ₂ ] and mixtures thereof are included. The electrolyte is preferably one that is difficult to oxidize even at a high potential, and LiPF ₆ is most preferred.

  Examples of organic solvents include propylene carbonate (PC), ethylene carbonate (EC), cyclic carbonates such as vinylene carbonate; Carbonates; cyclic ethers such as tetrahydrofuran (THF), 2-methyltetrahydrofuran (2MeTHF), dioxolane (DOX); chain ethers such as dimethoxyethane (DME) and diethoxyethane (DEE); γ-butyrolactone (GBL), Acetonitrile (AN) and sulfolane (SL) are included. These organic solvents can be used alone or as a mixed solvent.

  Examples of the polymer material include polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), and polyethylene oxide (PEO).

  Alternatively, a non-aqueous electrolyte may be a room temperature molten salt (ionic melt) containing lithium ions, a polymer solid electrolyte, an inorganic solid electrolyte, or the like.

  A room temperature molten salt (ionic melt) refers to a compound that can exist as a liquid at room temperature (15 to 25 ° C.) among organic salts composed of a combination of an organic cation and an anion. The room temperature molten salt includes a room temperature molten salt that exists alone as a liquid, a room temperature molten salt that becomes liquid when mixed with an electrolyte, and a room temperature molten salt that becomes liquid when dissolved in an organic solvent. In general, the melting point of a room temperature molten salt used for a nonaqueous electrolyte battery is 25 ° C. or less. The organic cation generally has a quaternary ammonium skeleton.

The polymer solid electrolyte is prepared by dissolving an electrolyte in a polymer material and solidifying it.
The inorganic solid electrolyte is a solid material having lithium ion conductivity.

4) Separator The separator may be formed of, for example, a porous film containing polyethylene, polypropylene, cellulose, or polyvinylidene fluoride (PVdF), or a synthetic resin nonwoven fabric. Especially, since the porous film formed from polyethylene or a polypropylene can melt | dissolve at a fixed temperature and can interrupt | block an electric current, safety | security can be improved.

5) Exterior member As the exterior member, a laminate film container or a metal container can be used. The thickness of the laminate film is preferably 0.5 mm or less, more preferably 0.2 mm or less. The metal container preferably has a thickness of 1 mm or less, a more preferable range is 0.5 mm or less, and a further preferable range is 0.2 mm or less.

  Examples of the shape of the exterior member include a flat type (thin type), a square type, a cylindrical type, a coin type, and a button type. Examples of the exterior member include a small battery exterior member loaded on a portable electronic device and the like, and a large battery exterior member loaded on a two-wheeled or four-wheeled automobile, depending on the battery size.

  As the laminate film, a multilayer film in which a metal layer is interposed between resin layers is used. The metal layer is preferably an aluminum foil or an aluminum alloy foil for weight reduction. For the resin layer, for example, a polymer material such as polypropylene (PP), polyethylene (PE), nylon, polyethylene terephthalate (PET) can be used. The laminate film can be formed into an exterior member by sealing by heat sealing.

  The metal container is made of aluminum or an aluminum alloy. The aluminum alloy is preferably an alloy containing elements such as magnesium, zinc, and silicon. When the alloy contains a transition metal such as iron, copper, nickel, or chromium, the content is preferably 1 part by weight or less. Thereby, long-term reliability and heat dissipation in a high temperature environment can be dramatically improved.

  Next, the nonaqueous electrolyte battery according to the second embodiment will be described more specifically with reference to the drawings. FIG. 2 is a cross-sectional view of a flat type nonaqueous electrolyte battery. FIG. 3 is an enlarged cross-sectional view of a portion A in FIG. Each figure is a schematic diagram for promoting the explanation of the embodiment and its understanding, and its shape, dimensions, ratio, etc. are different from the actual device, but these are considered in the following explanation and known techniques. Thus, the design can be changed as appropriate.

  The flat wound electrode group 9 is housed in a bag-shaped exterior member 10 made of a laminate film having a metal layer interposed between two resin layers. As shown in FIG. 3, the flat wound electrode group 9 is formed by winding a laminate of the negative electrode 11, the separator 12, the positive electrode 13, and the separator 12 in this order from the outside in a spiral shape and press-molding. Is done.

  The negative electrode 11 includes a negative electrode current collector 11a and a negative electrode material layer 11b. The negative electrode material layer 11b includes the negative electrode active material and the conductive agent according to the first embodiment. As shown in FIG. 2, the outermost negative electrode 11 has a configuration in which a negative electrode material layer 11b is formed on one surface on the inner surface side of the negative electrode current collector 11a. In other negative electrodes 11, negative electrode material layers 11b are formed on both surfaces of the negative electrode current collector 11a.

  The positive electrode 13 has a positive electrode material layer 13b formed on both surfaces of a positive electrode current collector 13a.

  As shown in FIG. 2, in the vicinity of the outer peripheral end of the wound electrode group 9, the negative electrode terminal 14 is connected to the negative electrode current collector 11 a of the outermost negative electrode 11, and the positive electrode terminal 15 is the positive electrode current collector of the inner positive electrode 13. 13a. The negative electrode terminal 14 and the positive electrode terminal 15 are extended to the outside from the opening of the bag-shaped exterior member 10. For example, the liquid nonaqueous electrolyte is injected from the opening of the bag-shaped exterior member 10. The wound electrode group 9 and the liquid non-aqueous electrolyte are completely sealed by heat-sealing the opening of the bag-shaped exterior member 10 with the negative electrode terminal 14 and the positive electrode terminal 15 interposed therebetween.

  The negative electrode terminal is formed of, for example, a material that is electrochemically stable at the Li storage / release potential of the negative electrode active material and has conductivity. Specifically, it is formed from copper, nickel, stainless steel, or aluminum, or an aluminum alloy containing elements such as Mg, Ti, Zn, Mn, Fe, Cu, and Si. The negative electrode terminal is preferably formed from the same material as the negative electrode current collector in order to reduce the contact resistance with the negative electrode current collector.

  The positive electrode terminal is formed of, for example, a material having electrical stability and conductivity in a range where the potential with respect to the lithium ion metal is 3 V or more and 5 V or less, preferably 3.0 V or more and 4.25 V or less. Specifically, it is formed from aluminum or an aluminum alloy containing elements such as Mg, Ti, Zn, Ni, Cr, Mn, Fe, Cu, and Si. The positive electrode terminal is preferably formed of the same material as the positive electrode current collector in order to reduce contact resistance with the positive electrode current collector.

  According to the second embodiment described above, since the negative electrode according to the first embodiment is provided, it is possible to effectively suppress decomposition of the electrolyte without impairing battery characteristics such as rate characteristics. . Therefore, according to the second embodiment, a nonaqueous electrolyte battery excellent in cycle stability, rate characteristics, charge / discharge efficiency, and gas generation resistance can be provided.

(Third embodiment)
The battery pack according to the third embodiment has one or a plurality of nonaqueous electrolyte batteries (unit cells) of the second embodiment. When a plurality of unit cells are provided, each unit cell is electrically connected in series or in parallel.

  Such a battery pack will be described in detail with reference to FIGS. As the unit cell, for example, a flat type battery can be used.

  A plurality of unit cells 21 composed of flat type non-aqueous electrolyte batteries are laminated so that the negative electrode terminal 6 and the positive electrode terminal 7 extending to the outside are aligned in the same direction, and are assembled by fastening with an adhesive tape 22. 23. These unit cells 21 are electrically connected to each other in series as shown in FIG.

  The printed wiring board 24 is disposed to face the side surface of the unit cell 21 from which the negative electrode terminal 6 and the positive electrode terminal 7 extend. As shown in FIG. 5, a thermistor 25, a protection circuit 26, and a terminal 27 for energizing external devices are mounted on the printed wiring board 24. An insulating plate (not shown) is attached to the surface of the protection circuit board 24 facing the assembled battery 23 in order to avoid unnecessary connection with the wiring of the assembled battery 23.

  The positive electrode side lead 28 is connected to the positive electrode terminal 7 positioned at the lowermost layer of the assembled battery 23, and the tip thereof is inserted into the positive electrode side connector 29 of the printed wiring board 24 and electrically connected thereto. The negative electrode side lead 30 is connected to the negative electrode terminal 6 located in the uppermost layer of the assembled battery 23, and the tip thereof is inserted into the negative electrode side connector 31 of the printed wiring board 24 and electrically connected thereto. These connectors 29 and 31 are connected to the protection circuit 26 through wirings 32 and 33 formed on the printed wiring board 24.

  The thermistor 25 detects the temperature of the unit cell 21, and the detection signal is transmitted to the protection circuit 26. The protection circuit 26 can cut off the plus side wiring 34a and the minus side wiring 34b between the protection circuit 26 and the energization terminal 27 to the external device under a predetermined condition. The predetermined condition is, for example, when the temperature detected by the thermistor 25 is equal to or higher than a predetermined temperature. The predetermined condition is when the overcharge, overdischarge, overcurrent, etc. of the cell 21 are detected. This detection of overcharge or the like is performed for each single cell 21 or the entire single cell 21. When detecting each single cell 21, the battery voltage may be detected, or the positive electrode potential or the negative electrode potential may be detected. In the latter case, a lithium electrode used as a reference electrode is inserted into each unit cell 21. In the case of FIG. 4 and FIG. 5, a wiring 35 for voltage detection is connected to each single cell 21, and a detection signal is transmitted to the protection circuit 26 through these wirings 35.

  Protective sheets 36 made of rubber or resin are disposed on the three side surfaces of the assembled battery 23 excluding the side surfaces from which the positive electrode terminal 7 and the negative electrode terminal 6 protrude.

  The assembled battery 23 is stored in a storage container 37 together with the protective sheets 36 and the printed wiring board 24. That is, the protective sheet 36 is disposed on each of the inner side surface in the long side direction and the inner side surface in the short side direction of the storage container 37, and the printed wiring board 24 is disposed on the inner side surface on the opposite side in the short side direction. The assembled battery 23 is located in a space surrounded by the protective sheet 36 and the printed wiring board 24. The lid 38 is attached to the upper surface of the storage container 37.

  In addition, instead of the adhesive tape 22, a heat shrink tape may be used for fixing the assembled battery 23. In this case, protective sheets are arranged on both side surfaces of the assembled battery, the heat shrinkable tube is circulated, and then the heat shrinkable tube is thermally contracted to bind the assembled battery.

  4 and 5 show the configuration in which the unit cells 21 are connected in series, but in order to increase the battery capacity, they may be connected in parallel. The assembled battery packs can be connected in series or in parallel.

  Moreover, the aspect of a battery pack is changed suitably by a use. As the use of the battery pack, those in which cycle characteristics with large current characteristics are desired are preferable. Specific examples include a power source for a digital camera, a vehicle for a two- to four-wheel hybrid electric vehicle, a two- to four-wheel electric vehicle, an assist bicycle, and the like. In particular, the vehicle-mounted one is suitable.

  According to the third embodiment described above, since the nonaqueous electrolyte battery according to the second embodiment is provided, a battery pack having excellent cycle stability, rate characteristics, charge / discharge efficiency, and gas generation resistance is provided. be able to.

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

  Hereinafter, based on an Example, the said embodiment is described in detail. The crystal structure of the active material was estimated by a powder X-ray diffraction method using Cu-Kα rays. The composition of the product was analyzed by ICP method, and it was confirmed that the target product was obtained.

<Example 1>
(Preparation of negative electrode)
First, Li ₂ CO ₃ and anatase TiO ₂ are mixed so that the molar ratio of Li: Ti is 4: 5, and calcined in the atmosphere at 850 ° C. for 12 hours, whereby the lithium occlusion / release potential is 1. A spinel type lithium titanium composite oxide Li ₄ Ti ₅ O ₁₂ of ₅ V vs. Li / Li ⁺ was obtained.

  14 g of a chloroauric acid aqueous solution with a 1% Au ion concentration was added to 100 g of a 0.2% carbon black suspension having an average particle size of 0.2 μm, and the mixture was stirred at 20 ° C. for 5 minutes. The suspension was stirred at 20 ° C. for 40 minutes, then solid-liquid separated with a centrifuge, and further 500 g of water was added and washed for 3 minutes. Centrifugation and washing operations are repeated three times to remove Cl ions, Au ions, etc. remaining in the suspension, and then the obtained solid is dried at 90 ° C. for 10 hours to obtain gold-supported carbon black. It was. By TEM analysis, it was confirmed that Au was supported in an island shape on the surface of the carbon black particles. Further, it was confirmed that Au particles having an average particle diameter of about 10 nm are supported on the surface of the carbon black particles.

A negative electrode mixture prepared by mixing 90 parts by weight of the obtained Li ₄ Ti ₅ O ₁₂ , ₅ parts by weight of the obtained gold-supporting carbon black and 5 parts by weight of PVdF as a binder was added to NMP to prepare a slurry. did. The obtained slurry was applied to an aluminum foil (current collector) having a thickness of 15 μm, dried and pressed to prepare a negative electrode having an electrode density of 2.0 g / cm ³ .

(Preparation of positive electrode)
85 parts by weight of layered rock salt type lithium cobalt oxide (LiCoO ₂ ) as a positive electrode active material, 5 parts by weight of graphite and 5 parts by weight of acetylene black as a conductive agent, and 5 parts by weight of PVdF as a binder were mixed. A positive electrode mixture was added to NMP to prepare a slurry. The obtained slurry was applied to an aluminum foil (current collector) having a thickness of 15 μm, dried and pressed to produce a positive electrode having an electrode density of 2.9 g / cm ³ .

(Preparation of non-aqueous electrolyte secondary battery)
The produced positive electrode and negative electrode were laminated | stacked through the separator, and this laminated body was wound in the spiral shape so that a negative electrode might become an outer peripheral side, and the electrode group was produced.

  A separator made of a polyethylene porous film was used as the separator.

  A nonaqueous electrolytic solution was prepared by dissolving 1.0 mol / l of lithium hexafluorophosphate in a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 2.

  The prepared electrode group and the prepared non-aqueous electrolyte were housed in an aluminum laminate container, and a non-aqueous electrolyte secondary battery was assembled. Note that the coating amounts of the positive electrode and the negative electrode were adjusted so that the total capacity of the assembled secondary battery was 1000 mAh.

<Examples 2 to 11 and Comparative Examples 2 to 5>
A nonaqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 except that the materials shown in Tables 1 and 2 below were used as catalyst materials for supporting the carbon black surface.

<Examples 12 to 14 and Comparative Example 10>
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the average particle diameter was adjusted to be as shown in Table 1 below when the gold particles were supported on carbon black.

<Example 15>
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that carbon nanofibers having an average particle size of 0.15 μm were used as the conductive particles.

<Example 16>
The same method as in Example 1, except that bronze type (monoclinic) titanium dioxide (TiO ₂ ) having a lithium occlusion / release potential of 1.0 V vs. Li / Li ⁺ was used as the active material for the negative electrode. A non-aqueous electrolyte secondary battery was produced.

<Comparative Examples 1 and 11>
A nonaqueous electrolyte secondary battery was produced in the same manner as in Examples 1 and 16, except that unsupported carbon black was used as the same weight part negative electrode conductive agent instead of the gold-supported carbon black synthesized in Example 1. .

<Comparative Example 6>
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the entire surface of the carbon black particles was coated with the catalyst layer.

<Comparative Example 7>
The same method as in Example 1 except that Au particles were supported on the surface of the negative electrode active material made of spinel type lithium titanate instead of carbon black, and unsupported carbon black was used as the same weight part negative electrode conductive agent. A non-aqueous electrolyte secondary battery was produced.

<Comparative Example 8>
Instead of 5 parts by weight of graphite and 5 parts by weight of acetylene black, 10 parts by weight of the gold-supported carbon black synthesized in Example 1 was used as the conductive agent for the positive electrode, and unsupported carbon black was used as the negative electrode conductive agent for the same part by weight. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1.

<Comparative Example 9>
A nonaqueous electrolyte secondary battery in the same manner as in Example 1 except that a carbonaceous material (lithium occlusion / release potential is 0.1 V vs Li / Li ⁺ ) is used instead of Li ₄ Ti ₅ O _{12 as} the negative electrode active material. Manufactured.

<First charge / discharge>
The batteries of Examples and Comparative Examples were charged and discharged for the first time by the following method. Except for Comparative Example 9, charging and discharging were performed at a current value of 1000 mA (1C) and a battery potential in the range of 3.0 V to 1.5 V. About the comparative example 9, the test was done by the same method except having changed the voltage range in charging / discharging into 4.2V-2.5V. The constant current charging of 200 mA was performed until the battery voltage reached the charging upper limit voltage in a constant temperature bath of 25 ° C. environment. After reaching the charge upper limit voltage, the voltage was maintained until the charge current became 50 mA or less. Thereafter, discharging was performed at a current value of 200 mA until the discharge lower limit voltage was reached. Thereafter, the charge / discharge current value was set to 1000 mA to obtain the first charge / discharge capacity.

<Evaluation of cycle capacity maintenance ratio>
Using the batteries of Examples and Comparative Examples, an electrode deterioration acceleration test was performed in a high temperature environment of 45 ° C. Charging / discharging was repeated 100 cycles (charging / discharging makes 1 cycle), and the discharge capacity retention rate was examined. Except for Comparative Example 9, charging and discharging were performed under the condition of a discharge current value of 1000 mA in a voltage range between 1.5 V and 3.0 V between the positive and negative electrodes. About the comparative example 9, the test was done by the same method except having changed the voltage range in charging / discharging into 4.2V-2.5V. For the capacity retention ratio other than Comparative Example 9, the discharge capacity ratio at 1000 mA from 3.0 V to 1.5 V before and after the cycle test was calculated. For the capacity retention rate of Comparative Example 9, the discharge capacity ratio at 1000 mA from 4.2 V to 2.5 V before and after the cycle test was calculated. The obtained capacity retention rates are shown in Tables 1 to 3 below.

<Evaluation of gas generation>
Using the batteries of Examples and Comparative Examples, an acceleration test of gas generation was performed in a high temperature environment of 60 ° C. The battery thickness after the first charge / discharge was measured and adjusted to a predetermined charge state, and then the battery was stored in a constant temperature bath at 60 ° C. for 4 weeks. The battery thickness after storage was measured and calculated as a ratio to the battery thickness before the storage test. The obtained ratios are shown in Tables 1 to 3 below as thickness changes.

<Rate characteristics>
The ratio of the 1C capacity to the 0.2C capacity when the discharge test was performed on the battery after the first charge / discharge at a discharge current value of 1000 mA (1C) and 200 mA (0.2 C) from 100% SOC (charged state). It calculated as a characteristic (1 C capacity | capacitance /0.2 C capacity | capacitance), and the result is shown in following Table 1-Table 3.

  As apparent from Tables 1 and 2, according to Examples 1 to 15, at least one metal selected from the group consisting of Cu, Ag, Au, Pd, In, Zn, Sn, Pb, Pt, and Cd. Alternatively, it can be seen that since the conductive particles in which the alloy particles are supported with an average particle diameter of 2 nm or more and 100 nm or less are used as the conductive agent, battery swelling is suppressed and the change in thickness is small. Moreover, it turns out that the capacity | capacitance maintenance factor after a high temperature cycle test is also high. This is probably because a stable film was formed on the surface of the active material due to the catalytic effect of the supported metal or alloy, and side reactions were suppressed. Furthermore, it has excellent rate characteristics. This is presumably because the coating on the active material surface has lithium ion conductivity.

  On the other hand, by comparing Examples 1 and 15, even when using vapor-grown carbon fibers or the like as the conductive particles in addition to carbon black, battery swelling is suppressed, and a battery with excellent high-temperature cycle life and rate characteristics is obtained. It can be seen that it can be realized.

  On the other hand, it can be seen that the battery of Comparative Example 1 using unsupported carbon black as the conductive agent swells due to gas generation during high-temperature storage. This is probably because a stable film was not formed on the active material surface during charge / discharge, and side reactions in subsequent cycles and storage tests could not be suppressed.

  If a metal other than Cu, Ag, Au, Pd, In, Zn, Sn, Pb, Pt, and Cd is used as in Comparative Examples 2-3, gas generation due to side reactions of the nonaqueous electrolyte can be suppressed. It cannot be seen that the battery thickness changes greatly. Also, the rate characteristics are inferior. This is because a stable coating film having lithium ion conductivity was not sufficiently formed because the reduction catalytic ability of the supported metal particles was low.

  When using a metal oxide like Comparative Examples 4-5, it turns out that the gas generation by the side reaction of a nonaqueous electrolyte cannot be suppressed, but a capacity | capacitance falls large after a cycle. Also, the rate characteristics are inferior. This is because the supported metal oxide particles have a low reduction catalytic ability, so that a stable coating having lithium ion conductivity is not sufficiently formed, and the electronic conductivity of the conductive particles is impaired by the metal oxide particles. This is because.

  When the entire surface of the conductive particles is covered with the catalyst layer as in the battery of Comparative Example 6, it can be seen that almost no improvement effect is obtained with respect to the capacity retention rate after the cycle and the battery swelling due to gas generation. This is considered to be because the surface area of the metal or alloy was greatly reduced by covering the entire surface of the conductive particles, and the catalytic ability was significantly reduced. Therefore, it is preferable that the metal or alloy is supported as particles without covering the entire surface of the conductive particles.

In the battery of Comparative Example 7 in which Au particles are supported on the surface of Li ₄ Ti ₅ O ₁₂ which is a negative electrode active material, the battery swelling due to gas generation is improved as compared with Comparative Example 1 using unsupported conductive particles. You can see that. This is probably because the Au particles directly suppressed side reactions on the active material surface. Therefore, when the rate characteristics of Example 1 and Comparative Example 7 were compared, it was confirmed that Example 1 was 0.97, whereas Comparative Example 7 had a rate characteristic of 0.78, which was low. . This is thought to be because the electrode reaction area was reduced because Au metal having no Li ion conductivity covered the surface of the active material. On the other hand, in the battery of Example 1, since a film having Li ion conductivity was formed, it is considered that the side reaction could be suppressed without impairing the rate characteristics.

From the comparison between Example 1 and Comparative Examples 8 and 9, it can be seen that the effect of loading metal or alloy particles on the surface of the conductive particles cannot be obtained for the positive electrode and the carbon negative electrode. Since the positive electrode is used in the high potential (2.5 V to 4.3 V vs. Li / Li ⁺ ) region, no reduction reaction occurs, and the carbon negative electrode has a potential at which the reduction reaction proceeds sufficiently even without catalytic action (0 .1 V vs. Li / Li ⁺ ) region, it is considered that the effect of the reduction catalyst was not obtained.

Moreover, even if it uses the metal chosen from the group which consists of Cu, Ag, Au, Pd, In, Zn, Sn, Pb, Pt, and Cd from Example 1, 12-14, and the comparative example 10, an average particle diameter is. It turns out that an effect is not acquired when it exceeds 100 nm. This is presumably because the formation of a stable coating was not performed because the surface area at which the catalytic effect was obtained decreased and the catalytic ability of the supported catalyst itself decreased due to the increase in particle diameter.

As is apparent from Table 3, even when bronze type TiO ₂ was used as the negative electrode active material as in Example 16, it was composed of Cu, Ag, Au, Pd, In, Zn, Sn, Pb, Pt and Cd. By using conductive particles carrying particles of at least one metal or alloy selected from the group for the conductive agent, battery swelling is suppressed and the thickness change is smaller than that of Comparative Example 11. I understand that. Moreover, it turns out that the capacity | capacitance maintenance factor and rate characteristic after a high-temperature cycle test are high compared with the comparative example 11. As shown in the effects of Tables 1 to 3, Occlusion of Li ions such as Li ₄ Ti ₅ O ₁₂ (1.5 V vs. Li / Li ⁺ ) and bronze type TiO ₂ (1.0 vs. Li / Li ⁺ ) -It turns out that it is effective for the negative electrode active material whose emission potential is 1 V vs Li / Li ⁺ or more and 3 V vs Li / Li ⁺ or less.

  According to the negative electrode for a nonaqueous electrolyte battery of at least one embodiment described above, at least one metal selected from the group consisting of Cu, Ag, Au, Pd, In, Zn, Sn, Pb, Pt, and Cd. Alternatively, by using a conductive agent containing conductive particles in which particles having an average particle diameter of 2 nm to 100 nm are supported by an alloy, it has excellent rate characteristics and can suppress decomposition of the nonaqueous electrolyte. Become.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Negative electrode active material, 2 ... Electroconductive particle, 3 ... Catalyst particle, 9 ... Electrode group, 10 ... Exterior member, 11 ... Negative electrode, 11a ... Negative electrode collector, 11b ... Negative electrode material layer, 12 ... Separator, 13 ... Positive electrode, 13a ... Positive electrode current collector, 13b ... Positive electrode material layer, 14 ... Negative electrode terminal, 15 ... Positive electrode terminal, 21 ... Single cell, 23 ... Battery assembly, 24 ... Printed circuit board, 25 ... Thermistor, 26 ... Protection circuit, 37 ... storage container, 38 ... lid.

Claims (5)

A negative electrode active material having a lithium insertion / release potential of 1 V vs Li / Li ⁺ or more and 3 V vs Li / Li ⁺ or less,
Selected from the group consisting of conductive particles, and supported on the surface of the conductive particles, having an average particle diameter of 2 nm to 100 nm and consisting of Cu, Ag, Au, Pd, In, Zn, Sn, Pb, Pt and Cd And a conductive agent comprising at least one metal or alloy particle.   2. The negative electrode for a non-aqueous electrolyte battery according to claim 1, wherein the conductive particles are at least one selected from the group consisting of graphites, carbon blacks, and vapor grown carbon fibers.   The negative electrode active material includes at least one selected from titanium-containing metal oxides having a structure of any one of spinel type, ramsdellite type, anatase type, rutile type, brookite type, and bronze type. Item 3. The negative electrode for a nonaqueous electrolyte battery according to Item 2. A negative electrode for a non-aqueous electrolyte battery according to any one of claims 1 to 3,
A positive electrode;
A non-aqueous electrolyte battery comprising a non-aqueous electrolyte.   A battery pack comprising the nonaqueous electrolyte battery according to claim 1.

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