JP2002110160A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery which is improved in discharge capacity. SOLUTION: In the nonaqueous electrolyte secondary battery provided with the negative pole 6 containing negative pole active material which electrochemically dopes/dedopes alkali metal, the positive pole 4 and nonaqueous electrolyte, the negative pole active material includes compound indicated by composition formula AxByC1-y (A is metal element. Atom ratio x and y indicate 0.2<=x<=1, 0.2<=y<=0.5, respectively).

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 In recent years, various portable electronic devices have become widespread due to rapid development of miniaturization technology of electronic devices. In addition, there is a demand for miniaturization of a battery serving as a power source of these portable electronic devices, and a non-aqueous electrolyte secondary battery having a high energy density has been receiving attention. Known negative electrode active materials for nonaqueous electrolyte secondary batteries include metallic lithium, carbon materials that occlude and release lithium, lithium alloys containing Si, Sn, and the like, amorphous chalcogen compounds, and the like. However, these negative electrode active materials have problems as described below.

[0003] Non-aqueous electrolyte secondary batteries using metallic lithium as the negative electrode active material have a very high energy density, but have a long battery life because dendritic crystals called dendrites tend to precipitate on the negative electrode during charging. Short and grown dendrites reach the positive electrode and cause an internal short circuit, which poses safety concerns.

On the other hand, when a lithium alloy or an amorphous chalcogen compound is used as a negative electrode active material, the lithium storage capacity of the negative electrode active material is increased, and the energy density of the secondary battery is improved. However, in a secondary battery including a lithium alloy as a negative electrode active material, pulverization of the negative electrode active material due to a charge / discharge cycle is likely to proceed, and a long life cannot be obtained. On the other hand, a secondary battery including an amorphous chalcogen compound as a negative electrode active material has a problem that the initial charge / discharge efficiency is low because an irreversible reaction is likely to occur at the time of the first charge.

[0005] Among the carbon materials that occlude and desorb lithium, graphitic carbon materials have problems such as lower capacity than lithium metal and lithium alloy and lower large current characteristics. Also, a carbon material having a low degree of graphitization, such as low-temperature calcined carbon or amorphous carbon, may be used as a negative electrode active material,
Although it has been proposed to use a mixture of the carbon material having a low degree of graphitization and graphite as a negative electrode active material, characteristics such as cycle characteristics and current load characteristics are not sufficient.

By the way, it is known that the addition of boron to a carbon material that inserts and extracts lithium improves the capacity of the negative electrode. However, since boron atoms dissolved in graphite crystallites are at most about several percent, the effect of capacity improvement is at most ten and several percent, and a sufficient discharge capacity has not been obtained.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a non-aqueous electrolyte secondary battery having an improved discharge capacity.

[0008]

A non-aqueous electrolyte secondary battery according to the present invention comprises a non-aqueous electrolyte secondary battery comprising a negative electrode containing a negative electrode active material for occluding and releasing an alkali metal, a positive electrode, and a non-aqueous electrolyte. In the following battery, the negative electrode active material has a composition formula of A _x
B _y C _1-y (A is a metal element, atomic ratio x, y is 0.2 ≦ x ≦
1, 0.2 ≦ y ≦ 0.5).

[0009]

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 nonaqueous electrolyte secondary battery will be described.

1) Positive Electrode The positive electrode has a structure in which a positive electrode active material layer containing an active material is supported on one or both surfaces of a positive electrode current collector.

Various oxides can be used for the positive electrode active material. Specifically, manganese dioxide, lithium manganese composite oxide, lithium-containing nickel cobalt oxide (eg, LiCoO ₂ ), lithium-containing nickel cobalt oxide (eg, LiNi _0.8 Co _0.2 O ₂ ), lithium manganese composite oxide (eg, LiMn ₂ O ₄ , Li
MnO ₂ ).

[0012] The positive electrode active material layer may contain a conductive agent in addition to the positive electrode active material. Examples of the conductive agent include acetylene black, carbon black, and graphite.

The positive electrode active material layer may contain a binder in addition to the positive electrode active material. Specific examples of the binder include, for example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), ethylene-propylene-diene copolymer (EPDM), styrene-butadiene rubber (SBR), and the like. Can be.

The mixing ratio of the positive electrode active material, the conductive agent and the binder is 80 to 95% by weight of the positive electrode active material, 3 to 20% of the conductive agent.
%, And a binder in a range of 2 to 7% by weight.

The thickness of one side of the positive electrode active material layer is 10 to 1
It is desirable that the thickness be in the range of 50 μm. Therefore, when it is carried on both surfaces of the positive electrode current collector, the total thickness of the positive electrode active material layer is desirably in the range of 20 to 300 μm.
A more preferable range on one side is 30 to 120 μm. By setting it within this range, it is possible to improve large current discharge characteristics and cycle life.

As the current collector, a conductive substrate having a porous structure or a non-porous conductive substrate can be used. The current collector preferably has a thickness of 5 to 20 μm. This is because in this range, the balance between electrode strength and weight reduction can be achieved.

2) Negative Electrode The negative electrode has a structure in which an active material-containing layer containing a negative electrode active material is supported on one or both surfaces of a negative electrode current collector.

The negative electrode active material has a composition formula of A _x B _y C
_1-y (A is a metal element, atomic ratio x, y is 0.2 ≦ x ≦ 1,
0.2 ≦ y ≦ 0.5). This negative electrode active material has a property of inserting and extracting an alkali metal such as lithium.

As the metal element A, typical metals, transition metals, rare earth metals and the like can be used. Among them, it is preferable to use an alkali metal or an alkaline earth metal. In particular, when an alkali metal (for example, lithium) serving as an active ion species of the nonaqueous electrolyte secondary battery is contained as the metal element A, the metal element A in the compound is occluded and released.
The effect of improving the discharge capacity is particularly large. Note that one or more metal elements can be used as the metal element A.

The reason for defining the atomic ratio x of the metal atom A in the above range will be described. When the atomic ratio x is less than 0.2, the charge / discharge capacity of the negative electrode active material decreases. It is presumed that this is because the layered structure of the hexagonal mesh layer in the fine structure of the negative electrode active material becomes unstable. On the other hand, if the atomic ratio x is 1
If it exceeds, an impurity phase is generated due to the excess metal element,
This has a negative effect on capacity reduction and load characteristics. A more preferable range of the atomic ratio x is 0.3 ≦ x ≦ 0.5.

The reason for defining the atomic ratio y of boron atoms in the above range will be described. When the atomic ratio y is less than 0.2, the charge / discharge capacity of the negative electrode active material decreases. This is considered to be because the π electron density of the hexagonal mesh layer in the fine structure of the negative electrode active material was reduced. On the other hand, when the atomic ratio y exceeds 0.5, the properties of the compound gradually approach those of the boron compound, so that the charge / discharge capacity of the negative electrode active material is significantly reduced.
A more preferable range of the atomic ratio y is 0.3 ≦ y ≦ 0.5.

Among the above compounds, preferred is Li
_0.5B_0.5C_0.5, Li_0.33B_0.33C_{0.6 7}, Li_0.2B_0.2
C_0.8, Mg_0.25B_0.5C_0.5, La_0.25B_0.5C_0.5, S
c_0.25B _0.5C_0.5And so on.

The compound is formed by stacking a large number of hexagonal reticular layers at an interval from each other, doping metal atoms A between the layers of the hexagonal retinal layers, and forming carbon atoms constituting the hexagonal retinal layers. It preferably has a fine structure (crystal structure) in which a part is substituted by a boron atom. When the compound has a fine structure as described above, the charge / discharge capacity of the negative electrode active material can be further improved. It is preferable that the angle between the hexagonal mesh layers is 3.4 ° or more and 4 ° or less. By setting the interlayer between 3.4 ° and 4 °, the stability of the crystal structure can be further increased.

The above compound is synthesized, for example, by mixing boron, carbon and metal element A and heating them under an inert atmosphere. The heating temperature varies depending on the type of the metal element A to be added, but is preferably in the range of 800 to 3000C. According to such a synthesis method, the hexagonal mesh layer can contain boron atoms up to a ratio of 1: 1 with respect to carbon atoms. In addition, when an element that easily volatilizes is used as the metal element A, a single-phase treatment such as (a) heating in a sealed ampule and (b) adding an extra metal element in advance as a volatile component is performed. It is important to obtain an active material.

The active material-containing layer may contain a binder. As the binder, for example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), ethylene-propylene-diene copolymer (EPDM), styrene-butadiene rubber (SBR) and the like can be used.

The thickness of the active material-containing layer is 10 to 150 μm.
m is desirable. Therefore, when the active material-containing layer is supported on both surfaces of the negative electrode current collector, the total thickness is in the range of 20 to 300 μm. The more preferable range of the thickness on one side is 30 to 100 μm. By setting it within this range, it is possible to improve large current discharge characteristics and cycle life.

As the current collector, a conductive substrate having a porous structure or a non-porous conductive substrate can be used.
These conductive substrates can be formed from, for example, copper, stainless steel, or nickel. The thickness of the current collector is 5
Preferably, it is 20 μm. This is because in this range, the balance between electrode strength and weight reduction can be achieved.

3) Non-aqueous Electrolyte The non-aqueous electrolyte includes a liquid non-aqueous electrolyte prepared by dissolving an electrolyte in a non-aqueous solvent, and a gel non-aqueous solution in which a polymer material is combined with a non-aqueous solvent and an electrolyte. Examples include an electrolyte, a solid nonaqueous 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, at least one kind of solvent selected from propylene carbonate (PC) and ethylene carbonate (EC) (hereinafter, referred to as a first solvent) and a solvent having a lower viscosity than PC and EC ( The second
) Is mainly used as the solvent.

As the second solvent, chain carbon is preferable. Among them, dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), diethyl carbonate (DEC), ethyl propionate, methyl propionate, γ-butyrolactone (BL), acetonitrile (A
N), ethyl acetate (EA), toluene, xylene, methyl acetate (MA) and the like are preferred. These second solvents are
They can be used alone or in the form of a mixture of two or more. In particular, the second solvent more preferably has a donor number of 16.5 or less.

The viscosity of the second solvent at 25.degree.
It is preferably 8 cmp or less. First in mixed solvent
Is preferably 10 to 80% by volume. A more preferred amount of the first solvent is 20 to 75% by volume.

As the electrolyte, for example, lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiP
F ₆ ), lithium borofluoride (LiBF ₄ ), lithium arsenic hexafluoride (LiAsF ₆ ), lithium trifluorometasulfonate (LiCF ₃ SO ₃ ), lithium bistrifluoromethylsulfonylimide [LiN (CF ₃ SO ₂ ) ₂ ]
And the like. Among them, LiPF ₆ , Li
Preferably, BF ₄ is used.

The amount of the electrolyte dissolved in the non-aqueous solvent is 0.1.
It is desirable to set it to 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. As such a separator, a porous separator is used. As a material of the separator, for example, a porous film containing polyethylene, polypropylene, or poly (vinylidene fluoride) (PVdF), a synthetic resin nonwoven fabric, or the like can be used. Among them, a porous film made of polyethylene, polypropylene, or both is preferable because the safety of the secondary battery can be improved.

It is preferable that the thickness of the separator is 30 μm or less. If the thickness exceeds 30 μm, the distance between the positive electrode and the negative electrode may increase, and the internal resistance may increase. The lower limit of the thickness is preferably set to 5 μm. If the thickness is less than 5 μm, the strength of the separator may be significantly reduced and an internal short circuit may easily occur. The upper limit of the thickness is more preferably 25 μm, and the lower limit is more preferably 10 μm.

The heat shrinkage of the separator when left at 120 ° C. for 1 hour is preferably 20% or less. If the heat shrinkage exceeds 20%, the possibility of short-circuiting when exposed to high temperatures increases. Heat shrinkage is 15%
It is more preferable to set the following.

The porosity of the separator is preferably in the range of 30 to 70%. This is due to the following reasons. If the porosity is less than 30%, it may be difficult to obtain high electrolyte retention in the separator. On the other hand, if the porosity exceeds 60%, sufficient separator strength may not be obtained. A more preferred range of porosity is 35-70%.

The separator has an air permeability of 500 seconds / 1.
It is preferably at most 00 cm ³ . Air permeability 500
If it exceeds sec / 100 cm ³ , it may be difficult to obtain high lithium ion mobility in the separator. The lower limit of the air permeability is 30 seconds / 100 cm.
³ If the air permeability is less than 30 seconds / 100 cm ³ , sufficient separator strength may not be obtained. The upper limit of the air permeability is 300 seconds / 100c
m ³ is more preferable, and the lower limit is more preferably 50 seconds / 100 cm ³ .

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.

In FIG. 1 described above, an example in which the present invention is applied to a non-aqueous electrolyte secondary battery using an outer package made of a metal can has been described, but a non-aqueous electrolyte secondary battery using an outer package made of a film material has been described. The same can be applied to batteries.
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 is a non-aqueous electrolyte secondary battery including a negative electrode including a negative electrode active material that occludes and releases an alkali metal, a positive electrode, and a non-aqueous electrolyte. The negative electrode active material has a composition formula of A _x B _y C
_1-y (A is a metal element, atomic ratio x, y is 0.2 ≦ x ≦ 1,
0.2 ≦ y ≦ 0.5, respectively).

Since such a negative electrode active material can improve the charge / discharge capacity, a long-life nonaqueous electrolyte secondary battery with an improved discharge capacity can be realized.

That is, when the amount of boron atoms to be dissolved in a carbonaceous material such as mesophase pitch-based carbon is increased, the π electron density on the hexagonal reticular layer constituting the graphite crystallite increases, but the hexagonal reticular layer increases. Since the stability of the layered structure is reduced, the amount of occluded alkali metal such as lithium decreases. By making the composition represented by A _{x By} C _{1 -y} as in the present invention, the valence 4 carbon atoms of the hexagonal reticular layer are replaced by the valence 3 boron atoms to thereby form the hexagonal reticular layer. As the π-electron density above increases, the metal atoms A doped between the layers of the hexagonal reticular layer increase the stability of the hexagonal reticular layer, so that more alkali metal cations such as lithium ions are intercalated between the layers. It can be inserted and released. As a result, a non-aqueous electrolyte secondary battery with improved discharge capacity and charge / discharge cycle life can be provided.

[0050]

EXAMPLES Specific examples of the present invention will be described below, and the effects thereof will be described. However, the present invention is not limited to the embodiments.

Example 1 Scaly artificial graphite was used as a raw material.
The boron powder and the lithium metal foil were weighed at an atomic ratio of 1: 1: 3 so that the total amount was 1 g, and sealed in a niobium ampoule under an argon atmosphere. Ampoule 600 in muffle furnace
After heating at 10 ° C. for 10 hours, Sample 1 was obtained.

Example 2 Scaly artificial graphite was used as a raw material.
Boron powder and magnesium metal powder in atomic ratio of 1: 1:
3 and weighed so that the total amount would be 1 g, and sealed in a niobium ampoule under an argon atmosphere. The ampoule was heated in a muffle furnace at 900 ° C. for 10 hours to obtain Sample 2.

(Example 3) Scaly artificial graphite as a raw material,
The boron powder and the lithium metal foil were weighed at an atomic ratio of 2: 1: 3 so that the total amount was 1 g, and sealed in a niobium ampoule under an argon atmosphere. Ampoule 600 in muffle furnace
After heating at 10 ° C. for 10 hours, Sample 3 was obtained.

Example 4 Scaly artificial graphite was used as a raw material.
Boron powder and lithium metal foil were weighed so that the total amount was 1 g at an atomic ratio of 4: 1: 3, and sealed in a niobium ampoule under an argon atmosphere. Ampoule 600 in muffle furnace
After heating at 10 ° C. for 10 hours, Sample 4 was obtained.

Example 5 Flake-like artificial graphite was used as a raw material.
The boron powder and the lanthanum mass were weighed at an atomic ratio of 2: 2: 1 so that the total amount was 1 g, and sealed in a niobium ampoule under an argon atmosphere. Ampoule in a muffle furnace at 1200 ° C
For 10 hours to obtain a sample 5.

Example 6 Scaly artificial graphite was used as a raw material.
Boron powder and scandium were weighed so that the total amount was 1 g at an atomic ratio of 2: 2: 1 and sealed in a niobium ampoule under an argon atmosphere. Ampoule in muffle furnace 1500
After heating at 10 ° C. for 10 hours, Sample 6 was obtained.

Example 7 Scaly artificial graphite was used as a raw material.
Boron powder, potassium in atomic ratio of 3: 2: 6 and total amount of 1
g, and sealed in a niobium ampoule under an argon atmosphere. Ampoule in muffle furnace at 600 ° C for 1
After heating for 0 hour, Sample 7 was obtained.

Example 8 Scaly artificial graphite was used as a raw material.
Boron powder and calcium were weighed so that the total amount was 1 g at an atomic ratio of 2: 2: 1 and sealed in a niobium ampoule under an argon atmosphere. Ampoule in a muffle furnace at 1000 ° C
For 10 hours to obtain a sample 8.

Example 9 Scaly artificial graphite was used as a raw material.
Boron powder, lithium metal foil in atomic ratio of 1: 1: 1.2
Was weighed so that the total amount became 1 g, and sealed in a niobium ampoule under an argon atmosphere. Ampoule in muffle furnace 6
After heating at 00 ° C. for 10 hours, Sample 9 was obtained.

(Example 10) As raw materials, flaky artificial graphite, boron powder, and lithium metal foil were used in an atomic ratio of 1: 1: 5.
Was weighed so that the total amount became 1 g, and sealed in a niobium ampoule under an argon atmosphere. Ampoule in muffle furnace 6
After heating at 00 ° C. for 10 hours, Sample 10 was obtained.

Example 11 As raw materials, flaky artificial graphite, boron powder, and lithium metal foil were used in an atomic ratio of 1: 1: 6.
Was weighed so that the total amount became 1 g, and sealed in a niobium ampoule under an argon atmosphere. Ampoule in muffle furnace 6
After heating at 00 ° C. for 10 hours, Sample 11 was obtained.

The obtained samples 1 to 11 were subjected to XRD measurement and charge / discharge test described below.

(XRD Measurement) The obtained samples were subjected to powder X-ray diffraction measurement, and the crystal structure of each sample was observed. As a result, a large number of hexagonal mesh layers were stacked at intervals from each other. It was confirmed that the cation of metal atom A was doped between the layers, and that the crystal structure was such that some of the carbon atoms constituting the hexagonal mesh layer were replaced with boron atoms. Also, by the powder X-ray diffraction,
The hexagonal mesh layers were measured, and the results are shown in Table 1 below.

(Charge / Discharge Test) Polytetrafluoroethylene was added to each of the obtained samples to form a sheet, which was then pressure-bonded to a stainless steel mesh and dried at 150 ° C. under vacuum to obtain a test electrode. The counter electrode and the reference electrode were metal Li. As the non-aqueous electrolyte, a solution prepared by dissolving 1M LiPF ₆ in a non-aqueous solvent in which ethylene carbonate (EC) and methyl ethyl carbonate (MEC) were mixed at a volume ratio of 1: 2 was prepared.

After a test cell having such a structure was fabricated in an argon atmosphere, a charge / discharge test was performed. The conditions for the charge / discharge test are as follows.
The battery was charged at a current density of mA / cm ² , further charged at a constant voltage of 0.01 V for 5 hours, and discharged up to 3 V at a current density of 1 mA / cm ² . Table 1 below shows the obtained discharge capacities.
Shown in

Comparative Example 1 As Comparative Sample 1, a mesophase pitch carbon fiber to which 3 wt% of boron was added was prepared.

(Comparative Example 2) B _{0.17 was introduced} by flowing benzene and boron chloride through a quartz tube in an electric furnace at 900 ° C.
Boron carbide represented by C _0.83 was prepared as Comparative Sample 2.

For the obtained comparative samples 1 and 2, the powder X
A line diffraction measurement was performed to observe the crystal structure of each sample. As a result, it was confirmed that some of the carbon atoms in the hexagonal mesh layer of the graphite crystallites were replaced with boron atoms. The layers between the hexagonal mesh layers were measured by the powder X-ray diffraction, and the results are shown in Table 1 below.

Further, the comparative samples 1 and 2 were subjected to a charge / discharge test in the same manner as described in the above-mentioned embodiment, and the results are shown in Table 1 below.

[0070]

[Table 1]

[0071] Table As shown in 1, Example 1 having a composition comprising a negative electrode active material containing a compound represented by A _x B _y C _1-y
It can be seen that the secondary battery of No. 11 has a higher discharge capacity than the secondary batteries of Comparative Examples 1 and 2.

[0072]

As described above, according to the present invention, it is possible to provide a non-aqueous electrolyte secondary battery having a high capacity and a long life.

[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.

[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) 4G046 AA08 5H029 AJ03 AK03 AL01 AM03 AM04 AM05 AM07 BJ02 DJ16 DJ17 HJ02 HJ13 5H050 AA08 BA17 CA08 CB01 EA10 EA24 FA17 FA18 FA19 HA02 HA13

Claims (2)

[Claims] A negative electrode containing a negative electrode active material of claim 1 an alkali metal absorbing and releasing, in the positive electrode and the nonaqueous electrolyte and the non-aqueous electrolyte secondary battery having an, the negative active material, the composition formula A _x B _y C _1-y (A is a metal element, atomic ratio x, y is 0.2 ≦ x ≦ 1, 0.2 ≦ y ≦ 0.
5 respectively). The non-aqueous electrolyte secondary battery comprising: 2. The compound according to claim 1, wherein a large number of hexagonal reticular layers are stacked, metal atoms A are doped between layers of the hexagonal reticular layers, and a part of carbon atoms constituting the hexagonal reticular layers are partially The non-aqueous electrolyte secondary battery according to claim 1, having a microstructure substituted with a boron atom.