JP2002110152A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-capacity nonaqueous electrolyte secondary battery with improved charge/discharge characteristics and, especially, high-rate discharge efficiency. SOLUTION: There are provided a positive electrode 4, a negative electrode 6 which comprises an negative electrode mix layer comprising a negative electrode active material which electrochemically doping/dedoping alkali metal and a current collector carrying the negative electrode mix layer, and a nonaqueous electrolyte. The negative electrode active material comprises compound particle containing at least one kind of element selected among Fe, Co, and Ni as well as at least one kind of element selected among Al, Si, Sn, and Sb, and a conductive particle layer which is formed at least at a part of the surface of the compound particle and comprises at least one kind selected among Ag, Ni, and Cu.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte secondary battery.

[0002]

2. Description of the Related Art Non-aqueous electrolyte secondary batteries using lithium metal, lithium alloys, lithium compounds, carbon materials and the like as negative electrode active materials are expected to be high energy density batteries, and are being actively researched and developed.

[0003] Among the nonaqueous electrolyte secondary batteries, a lithium ion having a positive electrode containing LiCoO ₂ or LiMn ₂ O ₄ as a positive electrode active material and a negative electrode containing a carbon material capable of occluding and releasing lithium as a negative electrode active material. BACKGROUND ART Batteries are widely put into practical use because pulverization of a negative electrode hardly occurs, and a long life and high safety can be obtained.

[0004] However, a secondary battery containing lithium metal, a lithium alloy, or a lithium compound as a negative electrode active material has not yet been put to practical use. When lithium metal is used for the negative electrode active material, the internal short circuit occurs because lithium degrades due to the reaction between the non-aqueous electrolyte and the lithium metal, and desorption occurs due to the generation of dendritic (dendritic) lithium due to repeated charge and discharge. This is because the problem of generation of swelling and reduction of cycle life occurs. On the other hand, a secondary battery provided with a negative electrode containing a lithium alloy such as a lithium-aluminum alloy suppresses the reaction between the nonaqueous electrolyte and the negative electrode, thereby improving the charge / discharge efficiency. Since the negative electrode is pulverized, a long life cannot be obtained.

From the viewpoint of further improving the negative electrode capacity,
Proposals have been made to use a chalcogen compound such as an oxide as a negative electrode active material. For example, JP-A-7-12227
Japanese Patent Publication No. 4 and JP-A-7-235293 disclose a secondary battery including a negative electrode containing SnO or SnO ₂ as a negative electrode active material. On the other hand, JP-A-7-
No. 288123 discloses SnSiO ₃ , SnSi _1-x P
_A secondary battery including a negative electrode containing an amorphous oxide such as xO ₃ as a negative electrode active material is disclosed.

[0006] However, secondary batteries provided with a negative electrode containing a negative electrode active material described in these publications have insufficient discharge capacity and cycle life. Further, as the capacity of the negative electrode increases, the current density during use (discharge) increases, so that it becomes difficult to obtain a high capacity when discharging a large current (high rate). Also, the secondary battery does not have sufficient high-rate discharge characteristics.

When a metal oxide or the like is used as a lithium insertion compound for the negative electrode, acetylene black is used as a conductive material to uniformly insert lithium ions by high-rate charging because the metal oxide itself has insufficient conductivity. It is indispensable to add or use graphite or graphite carbon. However, the electrical conductivity of these conductive materials is in the range of 10 ² to 10 ⁴ S / cm, and is 2 to 4 orders of magnitude lower than that of metal. It is difficult to provide conduction. Further, when an alloy compound having a specific gravity close to 10 times that of carbon is used as an active material, it is extremely difficult to uniformly mix carbon and the alloy compound, so that only a carbon-based conductive material has sufficient electric power to withstand high-rate use. It becomes more difficult to provide conduction.

In order to solve such a problem, Ag is added to the active material.
Increase the conductivity by mixing metal particles with high electrical conductivity such as
Although a method for improving the high-rate characteristics has been proposed, it was also difficult to uniformly mix the Ag particles, and sufficient characteristics could not be obtained.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and has a charge-discharge characteristic,
In particular, it is an object of the present invention to provide a high-capacity nonaqueous electrolyte secondary battery with improved high-rate discharge efficiency.

[0010]

A non-aqueous electrolyte secondary battery according to the present invention carries a positive electrode, a negative electrode mixture layer containing a negative electrode active material that absorbs and releases an alkali metal, and the negative electrode mixture layer. In a nonaqueous electrolyte secondary battery including a negative electrode having a current collector and a nonaqueous electrolyte, the negative electrode active material is Fe,
A compound particle containing at least one element selected from the group consisting of Co and Ni and at least one element selected from the group consisting of Al, Si, Sn and Sb, and formed on at least a part of the surface of the compound particle Ag, Ni
And a conductive particle layer made of at least one selected from the group consisting of Cu and Cu.

Another non-aqueous electrolyte secondary battery according to the present invention is:
Non-aqueous electrolyte secondary battery including a positive electrode, a negative electrode having a negative electrode mixture layer containing a negative electrode active material that occludes and releases an alkali metal, a negative electrode having a current collector on which the negative electrode mixture layer is supported, and a non-aqueous electrolyte In the above, the negative electrode active material includes a secondary particle composed of a compound primary particle having a conductive particle layer formed on at least a part of a surface thereof, and the compound primary particle includes Fe, C
the conductive particle layer is formed of a compound containing at least one element selected from the group consisting of o and Ni and at least one element selected from the group consisting of Al, Si, Sn and Sb; It is characterized by being composed of at least one selected from the group consisting of Ni and Cu.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A non-aqueous electrolyte secondary battery according to the present invention includes a positive electrode, a negative electrode, and a non-aqueous electrolyte. Hereinafter, the positive electrode, the negative electrode, and the non-aqueous electrolyte will be described.

(1) Positive electrode For the positive electrode, for example, a positive electrode active material, a conductive agent and a binder 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 this.

The positive electrode active material includes various oxides and sulfides. For example, manganese dioxide (MnO ₂ ),
Lithium manganese composite oxide (eg, LiMn ₂ O ₄ or LiMnO ₂ ), lithium nickel composite oxide (eg, LiNiO ₂ ), lithium cobalt composite oxide (Li
CoO ₂ ), lithium nickel cobalt composite oxide (eg, LiNi _{1 -x} Co _x O ₂ ), lithium manganese cobalt composite oxide (eg, LiMn _x Co _{1 -x} O ₂ ), vanadium oxide (eg, V ₂ O ₅ ) And the like. Also,
Organic materials such as a conductive polymer material and a disulfide-based polymer material are also included. Among them, lithium manganese composite oxide (LiMn ₂ O ₄ ), lithium nickel composite oxide (LiNiO ₂ ), lithium cobalt composite oxide (LiCoO ₂ ), and lithium nickel cobalt composite oxide (LiNi _0.8 Co _0.2 O) having a high battery voltage _2), lithium manganese cobalt composite oxides _{(LiMn x Co 1-x O} 2) is preferred.

Examples of the conductive agent include acetylene black, carbon black, graphite and the like.

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 80 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. preferable.

(2) Negative Electrode This negative electrode has a negative electrode mixture layer containing a negative electrode active material that occludes and releases an alkali metal, and a current collector on which the negative electrode mixture layer is carried.

The negative electrode active material comprises at least one element selected from the group consisting of Fe, Co and Ni and Al, S
at least one selected from the group consisting of i, Sn and Sb
And a conductive particle layer formed on at least a part of the surface of the compound particle and made of at least one selected from the group consisting of Ag, Ni and Cu.

The compound particles referred to herein include primary particles and secondary particles.

In particular, it is preferable that secondary particles composed of primary particles having a conductive particle layer formed on at least a part of the surface are used as the negative electrode active material. According to such secondary particles,
Since the electric conductivity of the negative electrode active material can be significantly improved, the high rate characteristics of the secondary battery can be further improved. Particularly preferred, while a conductive particle layer is formed on at least a part of the surface of the secondary particles,
The conductive particles are present in at least a part of the gap between the primary particles constituting the secondary particles.

In the compound, M is at least one element selected from the group consisting of Fe, Co and Ni, and X is at least one element selected from the group consisting of Al, Si, Sn and Sb. At this time, MXa (atomic ratio a is 0.2 ≦ a ≦ 6, more preferably 0.8 ≦ a ≦
3.2 is preferred. The compound having such a composition can further improve the discharge capacity and cycle life of the secondary battery.

As the compound, a compound containing an Sb element is preferable. The compound containing Sb can further improve the negative electrode capacity and cycle life. Among them, antimony compounds are desirable. Among the antimony compounds, CoSb ₃ , CoSb ₂ , CoSb, NiSb ₂ , N
iSb, FeSb ₂ , and FeSb are preferred.

Preferably, the conductive particle layer contains Ag. The conductive particle layer containing Ag can further improve high-rate discharge characteristics.

It is preferable that the average particle diameter of the conductive particles constituting the conductive particle layer is 1 nm or more and 1 μm or less. This is due to the following reasons. If the average particle size is less than 1 nm, the electric conductivity of the conductive particles themselves may be reduced, and high high-rate characteristics may not be obtained. On the other hand, if the average particle size exceeds 1 μm, the electrical conductivity of the negative electrode active material may be insufficient, and high high rate characteristics may not be obtained. A more preferred range of the average particle size is 1
It is not less than 0 nm and not more than 300 nm.

It is preferable that the content of the conductive particle layer in the negative electrode mixture layer is 0.1% by weight or more and 10% by weight or less. This is due to the following reasons.
If the content of the conductive particle layer is less than 0.1% by weight, it may be difficult to sufficiently improve the electric conductivity of the negative electrode active material. On the other hand, when the content of the conductive particle layer exceeds 10% by weight, the capacity of the negative electrode active material may be reduced. More preferred range of the content of the conductive particle layer,
0.3 to 3% by weight.

The negative electrode active material is produced, for example, by the method described below. First, according to the target composition, F
at least one selected from the group consisting of e, Co and Ni
Mixing at least one kind of powder selected from the group consisting of Al, Si, Sn and Sb with a kind of element, and 200-1000 ° C. under an inert gas atmosphere, a reducing atmosphere or under vacuum
Heat treatment at a temperature of In a heat treatment at a temperature lower than 200 ° C., it takes a long time to react to form a compound, resulting in poor productivity.
Elements having a high vapor pressure, such as n and Sb, are remarkably evaporated and dissipated, and the composition after heat treatment may be significantly different from the composition at the time of powder mixing.

The powder thus obtained is made of Fe, C
It is mainly composed of secondary particles of a compound containing at least one element selected from the group consisting of o and Ni and at least one element selected from the group consisting of Al, Si, Sn and Sb. Then, the obtained powder is an aqueous solution of silver nitrate,
When immersed in a nickel nitrate aqueous solution or a copper nitrate aqueous solution, Ag, Ni or Cu is adsorbed on the surface of the secondary particles and the surface of the primary particles constituting the secondary particles. When this is dried and fired, Ag, Ni
And at least one type of conductive particle layer selected from the group consisting of Cu and secondary particles formed by bonding the compound primary particles formed with the conductive particle layer. In addition, according to this method, the average particle size of the conductive particles contained in the secondary particles can be in the range of 1 nm or more and 1 μm or less.

The negative electrode is produced, for example, by suspending the negative electrode active material, conductive material and binder in a suitable solvent, applying the suspension to a metal foil such as a copper foil, drying and pressing.

Examples of the conductive agent include acetylene black, carbon black, graphite and the like.

Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine rubber, ethylene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC).
And the like.

The mixing ratio of the negative electrode active material, the conductive agent and the binder is preferably in the range of 70 to 95% by weight of the negative electrode active material, 0 to 25% by weight of the conductive agent, and 2 to 10% by weight of the binder. preferable.

(3) Non-aqueous Electrolyte The non-aqueous electrolyte may be a liquid non-aqueous electrolyte prepared by dissolving an electrolyte in a non-aqueous solvent, or a gel-like non-aqueous electrolyte obtained by combining a polymer material with a non-aqueous solvent and an electrolyte. Examples thereof include an aqueous electrolyte, a solid non-aqueous electrolyte in which an electrolyte is held in a polymer material, and an inorganic solid electrolyte having lithium ion conductivity. Among them, it is preferable to use a liquid non-aqueous electrolyte due to various characteristics.

As the non-aqueous solvent, known non-aqueous solvents can be used, and cyclic carbonates such as ethylene carbonate (EC) and propylene carbonate (PC);
It is preferable to use a non-aqueous solvent mainly composed of a mixed solvent of a cyclic carbonate and a non-aqueous solvent having a lower viscosity than the cyclic carbonate (hereinafter, a second solvent).

Examples of the second solvent include chain carbonates such as dimethyl carbonate, methyl ethyl carbonate and diethyl carbonate, γ-butyrolactone,
Examples of acetonitrile, methyl propionate, ethyl propionate, cyclic ethers such as tetrahydrofuran and 2-methyltetrahydrofuran, and chain ethers such as dimethoxyethane and diethoxyethane are given.

Examples of the electrolyte include an alkali salt, and a lithium salt is particularly preferable. As a lithium salt,
Lithium hexafluorophosphate (LiPF ₆ ), lithium borofluoride (LiBF ₄ ), lithium arsenide hexafluoride (LiA
sF ₆ ), lithium perchlorate (LiClO ₄ ), lithium trifluorometasulfonate (LiCF ₃ SO ₃ ), and the like. In particular, lithium hexafluorophosphate (LiPF
₆ ), lithium borofluoride (LiBF ₄ ) is preferred.

The amount of the electrolyte dissolved in the non-aqueous solvent is preferably 0.5 to 2 mol / L.

The above-mentioned gelled non-aqueous electrolyte is prepared, for example, by dissolving a non-aqueous solvent and an electrolyte in a polymer material and gelling by heat treatment or the like. Examples of the polymer material include a polymer of a monomer such as polyacrylonitrile, polyacrylate, polyvinylidene fluoride (PVdF), and polyethylene oxide (PECO), or a copolymer of the monomer and another monomer. Coalescence.

The solid electrolyte is prepared by dissolving the electrolyte in a polymer material and solidifying it. Examples of the polymer material include a polymer of a monomer such as polyacrylonitrile, polyvinylidene fluoride (PVdF), and polyethylene oxide (PEO), or a copolymer of the monomer and another monomer. Can be

Examples of the inorganic solid electrolyte include a ceramic material containing lithium. Among them, Li ₃ N, Li ₃ PO ₄ —Li ₂ S—SiS ₂ glass and the like can be mentioned.

When a liquid non-aqueous electrolyte or a gel non-aqueous electrolyte is used as the non-aqueous electrolyte, it is preferable to interpose a separator between the positive electrode and the negative electrode. Examples of such a separator include a synthetic resin nonwoven fabric, a polyethylene porous film, and a polypropylene porous film.

A cylindrical non-aqueous electrolyte secondary battery which is an example of the non-aqueous electrolyte secondary battery according to the present invention will be described in detail with reference to FIG.

For example, a bottomed cylindrical container 1 made of stainless steel has an insulator 2 disposed at the bottom. Electrode group 3
Are stored in the container 1. The electrode group 3 has a structure in which a band formed by laminating the positive electrode 4, the separator 5, the negative electrode 6, and the separator 5 is spirally wound so that the separator 5 is located outside.

The container 1 contains an electrolytic solution. The insulating paper 7 having a central opening is disposed above the electrode group 3 in the container 1. The insulating sealing plate 8
The sealing plate 8 is disposed at the upper opening of the container 1 and caulked in the vicinity of the upper opening inward.
Is fixed to the container 1. The positive electrode terminal 9 is fitted in the center of the insulating sealing plate 8. One end of the positive electrode lead 10 is connected to the positive electrode 4, and the other end is connected to the positive electrode terminal 9. The negative electrode 6 is connected to the container 1 as a negative electrode terminal via a negative electrode lead (not shown).

In FIG. 1, an example in which the present invention is applied to a cylindrical non-aqueous electrolyte secondary battery has been described. However, the present invention can be similarly applied to a rectangular non-aqueous electrolyte secondary battery. Further, the electrode group housed in the battery container is not limited to a spiral shape, but a positive electrode,
A configuration in which a plurality of separators and negative electrodes are stacked in this order may be adopted.

Further, in FIG. 1 described above, the exterior body made of a metal can is used, but an exterior body made of a film material may be used. As the film material, a laminate film including a thermoplastic resin layer and an aluminum layer is preferable.

The non-aqueous electrolyte secondary battery according to the present invention described above has a positive electrode, a negative electrode mixture layer containing a negative electrode active material that absorbs and releases an alkali metal, and a current collector on which the negative electrode mixture layer is supported. In a non-aqueous electrolyte secondary battery including a negative electrode having: and a non-aqueous electrolyte, the negative electrode active material is Fe, Co
And a compound particle containing at least one element selected from the group consisting of Ni and Ni and at least one element selected from the group consisting of Al, Si, Sn and Sb, and formed on at least a part of the surface of the compound particle. , Ag, Ni and Cu, and at least one conductive particle layer selected from the group consisting of Ag, Ni and Cu.

According to such a secondary battery, since the bonding strength (adhesion strength) between the compound particles and the conductive particles can be improved, the electric conductivity of the negative electrode active material can be improved. As a result, a non-aqueous electrolyte secondary battery having high capacity and excellent high-rate discharge characteristics can be realized.

The non-aqueous electrolyte secondary battery according to the present invention is a negative electrode having a positive electrode, a negative electrode mixture layer containing a negative electrode active material for occluding and releasing an alkali metal, and a current collector on which the negative electrode mixture layer is supported. In a non-aqueous electrolyte secondary battery including a non-aqueous electrolyte, the negative electrode active material includes a secondary particle composed of a compound primary particle having a conductive particle layer formed on at least a part of its surface, The compound primary particles are formed from a compound containing at least one element selected from the group consisting of Fe, Co and Ni and at least one element selected from the group consisting of Al, Si, Sn and Sb; The conductive particle layer is made of at least one selected from the group consisting of Ag, Ni and Cu.

According to such a secondary battery, the bonding strength between the conductive particles and the compound can be improved, and the conductive particle layer can be dispersed not only on the surface of the compound secondary particles but also inside the compound secondary particles. Therefore, the electric conductivity of the negative electrode active material can be significantly improved. As a result, the discharge capacity and high-rate discharge characteristics of the nonaqueous electrolyte secondary battery can be further improved.

In the non-aqueous electrolyte secondary battery according to the present invention, by setting the average particle size of the conductive particles to 1 nm or more and 1 μm or less, the electric conductivity of the negative electrode active material can be further improved. The discharge capacity and high-rate discharge characteristics of the water electrolyte secondary battery can be further improved.

[0052] In the non-aqueous electrolyte secondary battery according to the present invention, the content of the conductive particles in the negative electrode mixture layer is set to 0.1.
By setting the content to 1% by weight or more and 10% by weight or less, it is possible to improve the electric conductivity of the negative electrode active material while minimizing the decrease in the negative electrode capacity caused by blending the conductive particles. The discharge capacity and high-rate discharge characteristics of the water electrolyte secondary battery can be further improved.

The method for producing a negative electrode active material according to the present invention, that is, at least one element selected from the group consisting of Fe, Co and Ni and Al, Si, Sn and Sb
Immersing a compound powder containing at least one element selected from the group consisting of silver nitrate, nickel nitrate and copper nitrate in an aqueous solution of one or more nitrates selected from the group consisting of:
After drying and baking, a negative electrode active material having high electric conductivity can be easily produced with good reproducibility.

[0054]

Embodiments of the present invention will be described below in detail with reference to the drawings. However, the present invention is not limited to the embodiments without departing from the spirit of the invention.

Example 1 <Preparation of Positive Electrode> First, lithium cobalt was used as a positive electrode active material.
Oxide (LiCoO)_Two) 91% by weight powder and acetylene
2.5% by weight of black, 3% by weight of graphite,
4% by weight of polyvinylidene fluoride (PVdF) and N-meth
Mix with tylpyrrolidone (NMP) solution
Prepared. This slurry is made of aluminum having a thickness of 15 μm.
Apply to the foil current collector, dry and press
Extreme density of 3.0 g / cm ^ThreeWas produced.

<Preparation of Negative Electrode> Co powder and Sb powder having a purity of 99.9% and an average particle diameter of 20 μm were mixed at an atomic equivalent ratio of 1: 1.
And stirred sufficiently using a V mixer. Fill the mixed powder with sufficient stirring into an alumina crucible,
Heat treatment was performed at 560 ° C. for 24 hours in a stream of argon gas to react these powders. Was XRD analysis of the heat treated material, only the peak of the CoSb ₃ phase was confirmed, it was found that this substance is a CoSb ₃ single phase. The reaction product agglomerated by the reaction was pulverized using an agate mortar to obtain a CoSb ₃ alloy powder having an average particle size of 10 μm. CoS obtained
After immersing the b ₃ alloy powder in the AgNO ₃ solution, the powder was dried and fired at 200 ° C. to obtain a negative electrode active material powder.

When the obtained powder was analyzed by SEM-EDX, it was confirmed that the negative electrode active material powder had a structure as shown in the schematic diagrams of FIGS. That is, the surface of the CoSb ₃ secondary particles 11 has an average particle size of 3
A layer 12 of Ag particles of nm is formed. The primary particles 13 constituting the secondary particles 11 are joined by an Ag particle layer 12 existing between the primary particles 13. Such secondary particles 11 are in contact with carbon material particles 14 (carbon conductive agent 14) made of graphite and acetylene black.

85% by weight of this CoSb ₃ alloy powder, 5% by weight of graphite and 3% by weight of acetylene black
And 7% by weight of PVdF and an NMP solution were added and mixed to prepare a slurry. This slurry is 12 μm thick
A negative electrode having a structure in which the negative electrode mixture layer was supported on the current collector was produced by applying the solution to a current collector made of a copper foil, drying and pressing. The content of the Ag particle layer in the negative electrode mixture was 1% by weight.

<Preparation of Electrode Group> After the positive electrode, the separator made of a porous film made of polyethylene, the negative electrode, and the separator were laminated in this order, they were spirally wound so that the negative electrode was positioned at the outermost periphery. This was turned to produce an electrode group.

<Preparation of Nonaqueous Electrolyte> In a mixed solvent of ethylene carbonate (EC) and methyl ethyl carbonate (MEC), lithium hexafluorophosphate (LiPF ₄ ) was added to a mixed solvent (mixing volume ratio of 1: 2) in an amount of 1.0%. A non-aqueous electrolyte was prepared by dissolving the solution in mol / l.

The above-mentioned electrode group and the above-mentioned electrolytic solution were housed in stainless steel bottomed cylindrical containers, respectively, to assemble the above-mentioned cylindrical non-aqueous electrolyte secondary battery shown in FIG.

Examples 2 to 17 Elements were selected so as to have the compositions shown in Table 1 below, and sufficiently stirred using a V mixer. A sufficiently stirred mixed powder is filled in an alumina crucible, and is heated at 400 ° C. in an argon gas stream.
Heat treatment was performed at 700 ° C. for 24 to 100 hours, and these powders were reacted to obtain an alloy powder having a composition shown in Table 1 below. The reaction product aggregated by the reaction was pulverized using an agate mortar to obtain an alloy powder having an average particle diameter of 10 μm. The obtained alloy powder was immersed in an aqueous nitrate solution of a metal to be adhered, and then dried and fired at 150 ° C. to 250 ° C. to obtain a negative electrode active material powder.

Comparative Examples 1-4 Alloy powders having the same composition as in Examples 1-4 had an average particle size of 5 μm.
Ag powder or Cu powder of m was added and mixed to obtain a mixed powder. A negative electrode was produced in the same manner as in Example 1 except that the obtained mixed powder was used as a negative electrode active material. The content of the Ag powder or Cu powder in the negative electrode mixture was 1% by weight as in Example 1.

The negative electrode active material powder of Comparative Example 1 was subjected to SEM-ED
When analyzed by X, it was confirmed that the negative electrode active material powder had a configuration as shown in the schematic diagrams of FIGS. 4 and 5. That is, Ag particles 16 having an average particle size of 5 μm are dispersed on the surface of the CoSb ₃ secondary particles 15. Such secondary particles 15 are made of carbon material particles 14 (carbon-based conductive agent 1) made of graphite and acetylene black.
4) is in contact.

A non-aqueous electrolyte secondary battery was assembled in the same manner as in Example 1 except that the obtained negative electrode was used.

Comparative Examples 5 to 8 A negative electrode was produced in the same manner as in Example 1 except that only the alloy powder having the same composition as in Examples 1 to 4 was used as the negative electrode active material.

A non-aqueous electrolyte secondary battery was assembled in the same manner as in Example 1 except that the obtained negative electrode was used.

The obtained Examples 1 to 17 and Comparative Examples 1 to 8
After performing constant-voltage charging of 4 V at 0.5 C for 3 hours, the capacity at 0.5 C discharge (discharge end voltage 2.4 V) and the capacities at 1 C and 3 C were determined. The above results are summarized in Tables 1 and 2.

[0069]

[Table 1]

[0070]

[Table 2]

As shown in Table 1, in the secondary batteries of Examples 1 to 4, the degree of decrease in the discharge capacity when the discharge rate was increased to 1 C or 3 C was smaller than that in Comparative Examples 1 to 8. Understand.

On the other hand, the secondary batteries of Comparative Examples 1 to 8
It can be seen that the discharge capacity at the time of discharging at a high rate of 3C is reduced by 100 mAh or more as compared with that at the time of discharging at 0.5C.

[0073]

As described in detail above, according to the present invention, a non-aqueous electrolyte secondary battery having a high capacity and excellent high-rate characteristics can be provided.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a cylindrical non-aqueous electrolyte secondary battery which is an example of a non-aqueous electrolyte secondary battery according to the present invention.

FIG. 2 is a schematic view showing a negative electrode active material included in the nonaqueous electrolyte secondary battery of Example 1.

FIG. 3 is an enlarged sectional view showing the negative electrode active material of FIG. 2;

FIG. 4 is a schematic diagram showing a negative electrode active material included in a nonaqueous electrolyte secondary battery of Comparative Example 1.

5 is an enlarged view showing the negative electrode active material of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Outer body, 3 ... Electrode group, 4 ... Positive electrode, 5 ... Separator, 6 ... Negative electrode, 8 ... Sealing plate, 9 ... Positive electrode terminal.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H029 AJ02 AJ03 AK02 AK03 AK16 AL11 DJ08 DJ16 EJ01 HJ01 HJ05 5H050 AA02 AA08 BA17 CB11 DA10 EA03 EA04 EA05 FA17 FA18 HA01 HA05

Claims (4)

[Claims] 1. A non-aqueous electrolyte comprising a positive electrode, a negative electrode having a negative electrode mixture layer containing a negative electrode active material that occludes and releases an alkali metal, a negative electrode having a current collector on which the negative electrode mixture layer is supported, and a non-aqueous electrolyte. In the water electrolyte secondary battery, the negative electrode active material contains at least one element selected from the group consisting of Fe, Co, and Ni and at least one element selected from the group consisting of Al, Si, Sn, and Sb. A non-aqueous electrolyte secondary comprising: compound particles; and a conductive particle layer formed on at least a part of the surface of the compound particles and made of at least one selected from the group consisting of Ag, Ni, and Cu. battery. 2. A non-aqueous electrolyte comprising: a positive electrode; a negative electrode having a negative electrode mixture layer containing a negative electrode active material that occludes and releases an alkali metal; a negative electrode having a current collector on which the negative electrode mixture layer is supported; In the water electrolyte secondary battery, the negative electrode active material includes a secondary particle composed of a compound primary particle having a conductive particle layer formed on at least a part of a surface thereof, and the compound primary particle includes Fe, Co, and At least one element selected from the group consisting of Ni and Al, Si, Sn
And a compound containing at least one element selected from the group consisting of Sb, and the conductive particle layer,
A non-aqueous electrolyte secondary battery comprising at least one selected from the group consisting of Ag, Ni and Cu. 3. The average particle diameter of the particles of the conductive particle layer is as follows:
The non-aqueous electrolyte secondary battery according to claim 1, wherein the thickness is 1 nm or more and 1 μm or less. 4. The non-aqueous electrolyte according to claim 1, wherein the content of the conductive particles in the negative electrode mixture layer is 0.1% by weight or more and 10% by weight or less. Next battery.