JP2002110159A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve capacity characteristic and cycle characteristic of a nonaqueous electrolyte secondary battery. SOLUTION: In the nonaqueous electrolyte secondary battery comprising the positive pole 4, the negative pole 6 provided with a negative pole active material which electrochemically dopes and dedopes alkali metal and the nonaqueous electrolyte 5 put between the positive pole 4 and the negative pole 6, the negative pole active material composed of nonaqueous amorphous material indicated by formula (1) is used. LixM1yM2zM31-x-y-z (1) (In the formula, M1 is at least one type of element selected from group of Al, Ga, Si, and As. M2 is at least one type of element selected from large elements in electronegativity. M3 is at least one type of element selected from group of S, Se and P. X is 0<x<=0.5, y is 0<y<0.5, z is 0<z<0.5.).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD 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. So far, LiCoO ₂ , LiMn ₂ O _{4 and the} like have been used as the positive electrode active material,
As a negative electrode active material, a lithium ion battery using a carbon material that absorbs and releases lithium has been widely put into practical use.

On the other hand, a secondary battery using a lithium metal, a lithium alloy, or a lithium compound for a negative electrode has not been put to practical use yet. The main reason for this is that when lithium metal is used, lithium is degraded 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. There is a problem that the internal short circuit and the cycle life are short.

[0004] Studies have been made on using a lithium alloy or lithium compound for the negative electrode which solves such problems. In particular, in alloys such as lithium-aluminum alloys, the reactivity with the non-aqueous electrolyte is suppressed and the charge / discharge efficiency is improved.However, repeated charging / discharging causes the electrodes to become finer, which causes a problem in cycle characteristics. there were. Therefore, a carbon material that has a smaller capacity than these negative electrode active materials but reversibly stores and releases lithium is used. Since it had excellent cycle performance and safety without the problem of pulverization, it was put to practical use.

Under these circumstances, from the viewpoint of further increasing the capacity of the negative electrode, proposals have been made to use chalcogen compounds such as oxides and nitrides for the negative electrode. For example, SnO, SnO ₂
(JP-A-7-122274 and JP-Hei 7-235293), further proposal for improving the cycle property amorphous oxides such as SnSiO ₃ or SnSi _{1 -X} P _X O ₃ have been made (Japanese Patent JP-A-7-288123). However, further sufficient improvement in cycle characteristics and capacity is required.

[0006]

As described above, conventional non-aqueous electrolyte secondary batteries are required to have further improved cycle characteristics and improved capacity.

The present invention provides a non-aqueous electrolyte secondary battery having a high capacity and an excellent cycle life by using a negative electrode having a high capacity and excellent charge / discharge cycle performance in response to such a demand. is there.

[0008]

According to the present invention, there is provided a non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode having a negative electrode active material for occluding and releasing an alkali metal, and a non-aqueous electrolyte sandwiched between the positive electrode and the negative electrode. In a non-aqueous electrolyte secondary battery having an electrolyte, the negative electrode active material is an amorphous material represented by Formula (1).

Li _x M1 _Y M2 _z M3 _1-xyz (1) (where M1 is B, Al, Ga, Si, Ge and As
At least one element selected from the group of M2 is M1
At least one element selected from elements having a higher electronegativity than Li except for M3 is at least one element selected from the group consisting of S and Se. X is 0 <x ≦ 0.5, y
Is 0 <y <0.5, and z is 0 <z <0.5. Further, the non-aqueous electrolyte secondary battery of the present invention comprises a positive electrode, a negative electrode including a negative electrode active material that occludes and releases an alkali metal,
In a non-aqueous electrolyte secondary battery having the positive electrode and a non-aqueous electrolyte sandwiched between the negative electrode, the negative electrode active material is an amorphous material represented by Formula (2).

M1 _a M2 _b P _1-ab (2) (where M1 is B, Al, Ga, Si, Ge and As
At least one element selected from the group of M2 is M1
At least one element selected from elements having a higher electronegativity than Li except for a is 0 <a ≦ 0.5, b is 0 <
b <0.5. A non-aqueous electrolyte secondary battery according to the present invention is a non-aqueous electrolyte having a positive electrode, a negative electrode including a negative electrode active material that occludes and releases an alkali metal, and a non-aqueous electrolyte sandwiched between the positive electrode and the negative electrode. In the secondary battery, the negative electrode active material is an amorphous material represented by Formula (3).

[0011] _{Li l M1 m M2 n P 1} -lmn (3) ( wherein, M1 is B, Al, Ga, Si, Ge and As
At least one element selected from the group of M2 is M1
At least one element selected from elements having a higher electronegativity than Li except for l is 0 <l ≦ 0.5, m is 0 <
m <0.5, n is 0 <n <0.5. M2 is Ca, Sr, Ba, rare earth element (including Y), In, Sn, Sb, Zn, Cd, Cu and A
At least one element selected from the group g can be used.

[0012] The negative electrode active material may be a mixture of the amorphous material and a graphite material.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a non-aqueous electrolyte secondary battery (for example, a cylindrical 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).

Next, the positive electrode 4, the separator, the negative electrode 6, and the nonaqueous electrolyte will be described in detail. 1) Positive electrode 4 The positive electrode 4 is prepared by suspending a conductive agent and a binder in a positive electrode active material in a suitable solvent, applying the suspension to a current collector such as an aluminum foil, drying and pressing to form a strip electrode. It is produced by this.

The positive electrode active material includes various oxides and sulfides.
Is mentioned. For example, manganese dioxide (MnO_Two),
Lithium manganese composite oxide (eg, LiMn_TwoO_FourAlso
Is LiMnO_Two), Lithium nickel composite oxide (for example,
If LiNiO_Two), Lithium cobalt composite oxide (Li
CoO_Two), Lithium nickel cobalt composite oxide (example
For example, LiNi_1-xCo_xO_Two), Lithium manganese cobalt
Complex oxide (for example, LiMn_xCo_1-xO_Two), Vanajiu
Oxide (eg, V_TwoO_Five) And the like. Also,
Conductive polymer materials, disulfide polymer materials, etc.
Organic materials. A more preferable positive electrode is a battery electrode.
Lithium manganese composite oxide (LiMn
_TwoO_Four), Lithium nickel composite oxide (LiNi
O_Two), Lithium cobalt composite oxide (LiCoO)_Two),
Lithium nickel cobalt composite oxide (LiNi_0.8C
o_0.2O_Two), Lithium manganese cobalt composite oxide (L
iMn_xCo_1-xO _Two).

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. . 2) Separator 5 The separator is for preventing the positive electrode and the negative electrode from contacting each other, and is made of an insulating material. further,
One having a shape in which the electrolyte can move between the positive electrode and the negative electrode is used. Specific examples include a synthetic resin nonwoven fabric, a polyethylene porous film, a polypropylene porous film, and the like. 3) Negative electrode 6 The negative electrode 6 is prepared by suspending and mixing a negative electrode mixture composed of, for example, a negative electrode active material, a conductive agent and a binder in an appropriate solvent, and applying a coating solution to one or both surfaces of a current collector. And dried.

The present inventors have synthesized various compounds as the negative electrode active material and evaluated the characteristics thereof. As a result, the amorphous compound represented by the formula (1) (the first invention) was used as the negative electrode active material.
Use of the amorphous compound represented by the formula (2) (second invention) or the amorphous compound represented by the formula (3) (third invention) improves the cycle characteristics of the nonaqueous electrolyte secondary battery. ,
The inventors have confirmed that the improvement of the battery capacity can be achieved, and reached the present invention.

3-1) First, the negative electrode active material containing the amorphous compound represented by the formula (1) will be described.

The method for producing the negative electrode active material includes a high frequency melting method, an arc melting method, a sintering method, a super-quenching method, an atomizing method, a plating method, a CVD method, a sputtering method, a mechanical processing method, a rolling method, and a sol-melting method. Gel method and the like can be mentioned.
Particularly preferred are a mechanical treatment method, a super-quenching method and a sintering method.

A method for producing the negative electrode active material represented by the formula (1) by a mechanical processing method will be described. For example, Li and M
A compound consisting of 1 and S or Se, and a compound consisting of Li and M2 and a compound consisting of S or Se are mixed in a predetermined amount and subjected to a mechanical treatment to be mechanically mixed by a planetary ball mill. A method of mixing an intermetallic compound, carbon, and lithium sulfide as starting materials is also one of the effective means.

As a processing means for mechanically mixing, for example, the above-mentioned mixture is put into a mixing container containing balls such as a planetary ball mill, a screw ball mill, a rotary ball mill, and an attritor, and the container and the balls, or A method of mechanically giving an impact by a collision between balls is adopted.

When the mixing container is sealed, the mixing container is sealed in a device such as a dry box filled with an atmosphere of an inert gas such as argon, or the container is evacuated by providing an exhaust valve. In some cases, the treatment may be performed by introducing nitrogen gas. In order to ensure the hermeticity of such an apparatus, it is desirable to take measures such as filling the container with a double lid, or filling the apparatus itself with an inert atmosphere, or putting it in a vacuum chamber. When the atmosphere is an inert atmosphere, the purity of the inert gas is preferably controlled.

For example, the inert gas has an oxygen concentration of 100 p
pm or less and a water concentration of 50 ppm or less. The powder used as a raw material is also handled in an inert atmosphere,
It is desirable to avoid oxidation. When the amount of oxygen contained in the reaction atmosphere exceeds 100 ppm, the amount of impurity oxygen contained in the produced negative electrode active material represented by the formula (1) increases, and the battery characteristics may be degraded.

The mechanical treatment using a planetary ball mill or the like is preferably performed for a period of 1 to 1000 hours. If the treatment time is less than 1 hour, the occlusion characteristics do not change sufficiently,
On the other hand, when the time exceeds 1000 hours, the oxidation of the negative electrode active material gradually progresses, and the production cost increases.

The powder obtained by the mechanical mixing treatment preferably has a particle size of 0.1 to 50 μm. In addition, by performing heat treatment as needed, the crystallinity can be adjusted, and the amorphous material can be further stabilized. The processing temperature depends on the composition of the sample, but is about 100 ° C. to 500 ° C.
It is preferable to carry out in a temperature range of about ° C. The optimal heat treatment time varies depending on the heat treatment temperature,
0.1 to 500 hours, preferably 0.5 to 1 hour
00 hours, more preferably 1 to 50 hours. Further, in some cases, the element species mixed by the treatment may form an aggregate, and the occlusion property can be improved by the aggregation effect. At that time, the aggregation ratio is preferably set to 5% by weight or more.

At this time, the composition ratio of the compound made of an amorphous material is as follows:
0% or less, further 2% or more, 30% or less, M1 exceeding 0 and 50% or less, further 10% or more, 40% or less,
M2 is greater than 0 and less than or equal to 50%, furthermore, greater than or equal to 15% and 4
0% or less, M3 is more than 0 and 50% or less, and even 15
% Or more and 45% or less.

M1 is an element responsible for occlusion of lithium,
If this amount is less than 10%, the lithium absorption / desorption characteristics deteriorate. M2 or M3 is for imparting structural stability. If it is less than 15%, the structure becomes unstable, and the negative electrode active material becomes finer with charge / discharge, and the cycle characteristics may deteriorate. There is. Further, by incorporating Li in this form, it becomes possible to improve the lithium occlusion / release characteristics of the amorphous material.

In this sample, elements such as N and F may be contained as impurities as long as the characteristics are not impaired. The content of these impurities is 1% by weight each.
The following is preferred. However, when oxygen is contained as an impurity, unlike other impurities, the charge / discharge characteristics are significantly reduced. Therefore, the amount of impurity oxygen is preferably suppressed to 100 ppm or less.

The use of an amorphous material as the negative electrode active material is particularly effective in preventing the volume change of the negative electrode active material during occlusion of an alkali metal such as lithium, thereby improving the cycle characteristics without pulverization. It is possible to do.

3-2) Next, the negative electrode active material containing the amorphous compound represented by the formulas (2) and (3) will be described.

The method for producing the negative electrode active material is the same as that for the amorphous compound represented by the formula (1), such as a high-frequency melting method, an arc melting method, a sintering method, a super-quenching method, an atomizing method, a plating method, and a CVD method. , A sputtering method, a mechanical processing method, a rolling method, or a sol-gel method. Particularly preferred are a mechanical treatment method, a super-quenching method and a sintering method.

These negative electrode active materials are composed of a phosphorus compound of M1 and a phosphorus compound of M2 as a starting material (third invention), and a phosphorus compound of Li and M1 and a lithium compound of Li and M2.
(2nd invention) using a phosphorus compound as a starting material (second invention), mixing them in a predetermined amount, subjecting them to mechanical treatment, and mechanically mixing them with a planetary ball mill. A method of mixing an intermetallic compound, carbon, and lithium sulfide as starting materials is also one of the effective means.

As the processing means for mechanically mixing, the same method as described for the amorphous material shown in the formula (1) can be adopted.

When the mixing process is performed in a closed space, the mixing process is performed in a device such as a dry box filled with an atmosphere of an inert gas such as argon, or the container is evacuated by providing an exhaust valve. In some cases, the treatment may be performed by introducing nitrogen gas. In order to ensure the hermeticity of such an apparatus, it is desirable to take measures such as filling the container with a double lid, or filling the apparatus itself with an inert atmosphere, or putting it in a vacuum chamber. When the atmosphere is an inert atmosphere, the purity of the inert gas is preferably controlled.

For example, the inert gas has an oxygen concentration of 100 p
pm or less and a water concentration of 50 ppm or less. The powder used as a raw material is also handled in an inert atmosphere,
It is desirable to avoid oxidation. If the amount of oxygen contained in the reaction atmosphere exceeds 100 ppm, the amount of impurity oxygen contained in the produced negative electrode active material represented by the formula (2) or (3) increases, and the battery characteristics may decrease. is there.

The mechanical treatment using a planetary ball mill or the like is preferably performed for a period of 1 to 1000 hours. If the treatment time is less than 1 hour, the occlusion characteristics do not change sufficiently,
On the other hand, if it exceeds 1000 hours, oxidation proceeds gradually,
Manufacturing costs also increase.

The powder obtained by the mechanical treatment preferably has a particle size of 0.1 to 50 μm. Further, heat treatment may be performed if necessary. The processing temperature depends on the composition of the sample, but is about 100 ° C. to 500 ° C.
It is preferable to carry out in a temperature range of about ° C. The optimal heat treatment time varies depending on the heat treatment temperature,
0.1 to 500 hours, preferably 0.5 to 1 hour
00 hours, more preferably 1 to 50 hours. Further, in some cases, the element species mixed by the treatment may form an aggregate, and the occlusion property can be improved by the aggregation effect. At that time, the aggregation ratio is preferably set to 5% by weight or more.

At this time, the composition ratio of the amorphous material represented by the formula (2) is a molar ratio.
0% or less, further 10% or more and 40% or less, M2 is more than 0 and 50% or less, further 15% or more and 40% or less
3 is more than 0 and 50% or less, and further 15% or more and 40%
It is preferable to set the following.

Further, by incorporating lithium into the amorphous material represented by the formula (2) and forming a compound represented by the formula (3), the occlusion ability of an alkali metal can be further improved. . As the composition ratio, lithium exceeds 0 and 50% or less, further 2% or more and 30% or less, M1 exceeds 0 and 50% or less, further 10% or more and 40% or less, and M2 exceeds 0 or less. 50% or less, furthermore, 15% or more and 40% or less, M3 is more than 0 and 50% or less, further 1
It is preferable that the content be 5% or more and 40% or less.

It should be noted that the amorphous material according to the present invention does not need to be completely amorphous, and the peaks obtained by X-ray diffraction using CuKα as a source are the peaks of the three strong lines. Among them, at least one peak has a half width Δ (2
Θ) may be any compound that satisfies 2 ° ≦ Δ (2Θ).
Here, the three strong lines mean up to the third peak counted from the peak having the maximum intensity among the peaks obtained by X-ray diffraction. The reason for defining the Δ (2 前 記) is as follows.

When the half width Δ (2Θ) is less than 2 °, the amount of occluded alkali metal decreases and the capacity of the battery decreases. On the other hand, the half width Δ (2 値) desirably satisfies 50 ° ≧ Δ (2Θ). When the half width Δ (2Θ) is larger than 50 °, the occlusion rate of the alkali metal becomes extremely low.

Further, it is desirable that 5 ° ≦ Δ (2 °) ≦ 20 °.

By having such a microcrystalline structure or an amorphous structure, a change in volume during occlusion of an alkali metal is particularly suppressed, and the crystal is not pulverized, and a long life can be achieved. .

Further, as a negative electrode active material, a carbon material having a high occlusion ability of an alkali metal is added to form a mixture of the above-mentioned amorphous material and this carbon material, thereby increasing the occlusion amount of the alkali metal. be able to. As the carbon material used for such a negative electrode active material, a graphite-based carbon material is preferable, and more specifically, mesophase pitch carbon fiber (MCF) or the like is preferable.

Further, as the conductive agent used for the negative electrode, a carbon material is usually used. As long as the carbon material used for the negative electrode active material has both high occlusion properties and conductivity of an alkali metal, the above-described carbon material used as the negative electrode active material can also be used as a conductive agent. However, since only graphite having a high carbon occlusion property such as the mesophase pitch carbon fiber exemplified has low conductivity, as the carbon material used as the conductive agent, for example, acetylene black, carbon black, etc. may be used for the negative electrode. preferable.

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

The compounding 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.

4) Nonaqueous Electrolyte The nonaqueous electrolyte is a liquid electrolyte prepared by dissolving an electrolyte in a nonaqueous solvent, or a polymer gel containing the nonaqueous solvent and the electrolyte in a polymer material. Electrolyte,
Examples include a solid polymer electrolyte containing only the above-mentioned electrolyte and an inorganic solid electrolyte having lithium ion conductivity.

As the liquid electrolyte, a known non-aqueous solvent obtained by dissolving a lithium salt as an electrolyte in a non-aqueous solvent of a lithium battery can be used.
It is preferable to use a cyclic carbonate such as C) or propylene carbonate (PC), or 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,
Acetonitrile, methyl propionate, ethyl propionate, cyclic ethers such as tetrahydrofuran and 2-methyltetrahydrofuran, and chain ethers such as dimethoxyethane and diethoxyethane are exemplified.

Examples of the electrolyte include an alkali salt, and in particular, a lithium salt. As lithium salts, lithium hexafluorophosphate (LiPF ₆ ), lithium borofluoride (LiBF ₄ ), lithium arsenic hexafluoride (LiAsF ₆ ), lithium perchlorate (LiClO ₄ ), lithium trifluorometasulfonic acid (LiCF ₆ ) ₃ SO ₃ ). In particular, lithium hexafluorophosphate (LiPF ₆ ) and lithium borofluoride (LiBF ₄ ) are preferable. The amount of the electrolyte dissolved in the non-aqueous solvent is
It is preferably 0.5 to 2.0 mol / l.

The gel electrolyte is obtained by dissolving the solvent and the electrolyte in a polymer material to form a gel. The polymer material may be polyacrylonitrile, polyacrylate, polyvinylidene fluoride (PVdF), polyethylene oxide (PEC).
Examples thereof include a polymer of a monomer such as O) or a copolymer with another monomer.

As the solid electrolyte, the above-mentioned electrolyte is dissolved in a polymer material and solidified. Polymer materials include polyacrylonitrile and polyvinylidene fluoride (PVd
F), a polymer of a monomer such as polyethylene oxide (PEO) or a copolymer with another monomer. Further, as the inorganic solid electrolyte, a ceramic material containing lithium may be used. Among them, Li ₃ N, Li ₃ PO ₄ —Li ₂ S—SiS ₂ glass and the like can be mentioned.

Although an example in which the present invention is applied to a cylindrical non-aqueous electrolyte secondary battery has been described with reference to FIG. 1 described above, 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.

[0059]

EXAMPLES Examples 1 to 19 <Preparation of Positive Electrode> First, 91% by weight of lithium cobalt oxide (LiCoO ₂ ) powder as a positive electrode active material was added to acetylene black.
5% by weight, 3% by weight of graphite, 3.5% by weight of polyvinylidene fluoride (PVdF) and N-methylpyrrolidone
(NMP) solution was added and mixed, applied to a 15 μm-thick aluminum foil current collector, dried, and pressed to produce a positive electrode having an electrode density of 3.0 g / cm ³ .

<Preparation of Negative Electrode> As the negative electrode active material, Li was used.
And Tables 1 and M1 sulfide shown in Table 2 (some have Se compound) powder and sulfides M2 shown in Li and Table 2 (or Se compound) powder, in some embodiments further Li, M1
Alternatively, the M2 powder was mixed with a composition ratio (Li: M
1: M2: M3 = x: y: z: 1-xy)
It was produced by performing a treatment at 300 rpm for 1 to 10 hours using a planetary ball mill.

After that, 85% by weight of this powder, 5% by weight of graphite as a conductive agent, 3% by weight of acetylene black also as a conductive agent, 7% by weight of PVdF and NMP
The solution was added and mixed, applied to a current collector made of a copper foil having a thickness of 11 μm, dried, and pressed to produce a negative electrode.

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

<Adjustment of Non-Aqueous Electrolyte> Further, lithium hexafluorophosphate (LiPF ₆ ) was added to a mixed solvent of ethylene carbonate (EC) and methyl ethyl carbonate (MEC) in a mixing volume ratio of 1: 2 (1.0%). A non-aqueous electrolyte solution was prepared by dissolving in mol / L.

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

For the obtained secondary battery, a charging current of 1 A
Charge to 4.2V for 2.5 hours, and then to 2.7V
The discharge capacity at the time of discharging at A was measured. Further, the capacity retention rate when the charge and discharge were repeated 300 times (capacity at the 300th cycle when the first capacity was set to 100) was measured. Table 1 shows the results. The discharge capacity is shown as a ratio when the discharge capacity in Comparative Example 1 described later is set to 1.

[Table 1]

[Table 2] Example 20 A battery was fabricated in the same manner as in Example 1 except that 10% of MCF was added to the raw material powder of the negative electrode active material, and the obtained discharge capacity and capacity retention were evaluated. The half-width Δ (2Θ) of the obtained negative electrode active material was 30 °, and the discharge capacity was 1.
5. The capacity retention ratio was 0.9.

Comparative Example 1 Mesophase pitch-based carbon fibers heat-treated at 3050 ° C. as a negative electrode active material (having a fiber diameter of 10 μm and an average fiber length of 2
2 μm, average plane spacing d (002) is 0.3353 nm,
Example 1 was repeated except that a negative electrode was manufactured under the same conditions as described above using a powder having a specific surface area of 5 m ² / g) by a BET method.
A battery was prepared in the same manner as described above, and the obtained battery was evaluated for discharge capacity and capacity retention. The capacity retention was 0.7, and the discharge capacity obtained here was 1.

Examples 21 to 41 As the negative electrode active materials, a phosphorus compound powder of M1 and a phosphorus compound powder of M2 were used.
1 or M2 powder in the composition ratio (L
i: M1: M2: P = x: y: z: 1-x-y-z) and 1 at 300 rpm using a planetary ball mill.
It was produced by treating for 10 to 10 hours.

A battery was prepared in the same manner as in Example 1 except that this negative electrode active material was used, and the obtained battery was evaluated for discharge capacity and capacity retention. The results are shown in Tables 3 and 4.

[Table 3]

[Table 4] Examples 42 and 43 The discharge capacity and capacity retention obtained in the same manner as in Examples 21 and 41 except that 15% of MCF was added to the raw material powder of the negative electrode active material were evaluated. The half widths Δ (2 °) of the obtained negative electrode active material were 20 ° and 30 °, respectively, the discharge capacity of the battery was 1.6 and 1.7, and the capacity retention ratio was 0.87 and 0.9.
Met.

As is clear from the results of these examples,
It can be seen that the batteries of Examples using the negative electrode active material according to the present invention have higher battery capacity and higher cycle characteristics than Comparative Example 1.

[0070]

As described above, according to the present invention, a lithium secondary battery having improved discharge capacity and cycle life can be provided.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a lithium secondary battery according to the present invention.

[Explanation of symbols]

 1 container 3 electrode group 4 positive electrode 5 separator 6 negative electrode 8 sealing plate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H029 AJ03 AJ05 AK03 AL01 AM03 AM04 AM05 AM07 BJ02 BJ14 DJ16 DJ18 HJ02 5H050 AA07 AA08 BA17 CA08 CB01 CB30 EA09 EA10 EA24 FA20 GA10 HA02

Claims (5)

[Claims] 1. A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode having a negative electrode active material for occluding and releasing an alkali metal, and a non-aqueous electrolyte sandwiched between the positive electrode and the negative electrode. The substance is an amorphous material represented by the formula (1), wherein the nonaqueous electrolyte secondary battery is provided. Li _x M1 _Y M2 _z M3 _1-xyz (1) (where M1 is B, Al, Ga, Si, Ge and As
At least one element selected from the group of M2 is M1
At least one element selected from elements having a higher electronegativity than Li except for M3 is at least one element selected from the group consisting of S and Se. X is 0 <x ≦ 0.5, y
Is 0 <y <0.5, and z is 0 <z <0.5. ) 2. A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode having a negative electrode active material for occluding and releasing an alkali metal, and a non-aqueous electrolyte sandwiched between the positive electrode and the negative electrode. A non-aqueous electrolyte secondary battery, wherein the substance is an amorphous material represented by the formula (2). M1 _a M2 _b P _1-ab (2) (where M1 is B, Al, Ga, Si, Ge and As
At least one element selected from the group of M2 is M1
At least one element selected from elements having a higher electronegativity than Li except for X is 0 <a ≦ 0.5, b is 0 <
b <0.5. ) 3. A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode having a negative electrode active material that occludes and releases an alkali metal, and a non-aqueous electrolyte sandwiched between the positive electrode and the negative electrode. The substance is an amorphous material represented by the formula (3), wherein the nonaqueous electrolyte secondary battery is provided. _{Li l M1 m M2 n P 1} -lmn (3) ( wherein, M1 is B, Al, Ga, Si, Ge and As
At least one element selected from the group of M2 is M1
At least one element selected from elements having a higher electronegativity than Li except for l is 0 <l ≦ 0.5, m is 0 <
m <0.5, n is 0 <n <0.5. ) 4. M2 is Ca, Sr, Ba, rare earth element (including Y), In, Sn, Sb, Zn, Cd, C
4. The non-aqueous electrolyte secondary battery according to claim 1, wherein the secondary battery is at least one element selected from the group consisting of u and Ag. 5. The non-aqueous electrolyte secondary battery according to claim 1, wherein the negative electrode active material is a mixture of the amorphous material and a graphite-based material.