JP2000036323A - Non-aqueous secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve energy quantity of a lithium secondary battery, and improve the cycle lifetime thereof by forming the battery out of a positive electrode having positive electrode active material as a transition metal oxide capable of absorbing and releasing lithium, a negative electrode having negative electrode material using the compound including a silicon atom, and the non- aqueous electrolyte. SOLUTION: A positive electrode having positive electrode active material LiCoO2 as a transition metal oxide capable of absorbing and releasing lithium and a mixture material of acetylene black and polyvinylidene fluoride is manufactured. A negative electrode having negative electrode material of the alloy including a silicon atom and having 0.01-50 μm of mean grain size and including at least one kind or more of alkali earth group metal, transition metal and semimetal is manufactured. Furthermore, the colorless electrolyte having a specific gravity at 1.135 and formed by dissolving ethylene carbonate in the di-edthyl carbonate little by little and dissolving LiBF4 and LiPF6 in order is filled between the positive electrode and the negative electrode. With this structure, the discharging capacity, energy quantity and cycle lifetime are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a non-aqueous secondary battery, and more particularly to a lithium secondary battery having a high capacity and a long cycle life.

[0002]

2. Description of the Related Art In a lithium secondary battery using a negative electrode material containing no lithium metal and a positive electrode active material containing lithium, first, lithium contained in the positive electrode active material is inserted into the negative electrode material to increase the activity of the negative electrode material. . This is the charging reaction, and the reverse reaction of inserting lithium ions from the negative electrode material into the positive electrode active material is the discharging reaction. Carbon is used as this type of lithium battery negative electrode material.
The theoretical capacity of carbon (C ₆ Li) is 372 mAh / g, and an even higher capacity negative electrode material is desired. on the other hand,
It is well known that the theoretical capacity of silicon, which forms an intermetallic compound with lithium, exceeds 4000 mAh / g and is larger than that of carbon. For example, JP-A-5-7446
No. 3 discloses single-crystal silicon.
9602 discloses amorphous silicon. In the case of alloys containing silicon, examples of Li-Al alloys containing silicon are described in JP-A-63-66369 (19% by weight of silicon) and JP-A-63-174275 (silicon is 0.05 to 1.0%).
0% by weight) and 63-285865 (1 to 5% by weight of silicon). However, since all of these alloy patent applications mainly use lithium, a compound containing no lithium was used as the positive electrode active material.
Further, in Japanese Patent Application Laid-Open No. 4-109562, silicon is 0.05%.
~ 1.0 wt% alloy is disclosed. JP-A-62-2
226563 discloses a method of mixing a graphite powder with a metal that can be alloyed with lithium. However, none of them has a poor cycle life and has not been put to practical use. It is presumed that the cycle life of silicon is inferior because the electron conductivity is low, the volume is expanded by lithium insertion, and the particles are pulverized.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to increase the energy amount and the cycle life of a lithium secondary battery.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a positive electrode having a positive electrode active material, a negative electrode having a negative electrode material, and a non-aqueous secondary battery comprising a non-aqueous electrolyte. Is a transition metal oxide containing lithium,
The problem was solved by a nonaqueous secondary battery characterized in that a compound containing a silicon atom was used as the negative electrode material.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments. (1) In a non-aqueous secondary battery including a positive electrode having a positive electrode active material, a negative electrode having a negative electrode material, and a non-aqueous electrolyte, the positive electrode active material is a transition metal oxide capable of inserting and releasing lithium. A non-aqueous secondary battery characterized by using a compound containing a silicon atom as the negative electrode material. (2) The silicon compound of the item (1) has an average particle size of 0.1.
A non-aqueous secondary battery having a size of 01 to 50 μm. (3) A non-aqueous secondary battery in which the silicon compound of (1) is an alloy. (4) The non-aqueous secondary battery according to item (3), wherein at least one of the metals other than silicon is an alkaline earth metal, a transition metal, or a metalloid. (5) At least one of the metals of item (3) or (4) is Ge, Be, Ag, Al, Au, Cd, Ga, In, S
b, Sn, Zn non-aqueous secondary battery. (6) In the item (5), Mg, Fe, Ni, C
A non-aqueous secondary battery containing at least one selected from the group consisting of o, Ti, Mo, and W. (7) A non-aqueous secondary battery in which the atomic ratio of metal to silicon according to item (6) is more than 0 and not more than 20%. (8) A nonaqueous secondary battery according to items (3) to (7), wherein the atomic ratio of the metal to silicon is 5 to 90%. (9) A non-aqueous secondary battery obtained by firing the alloy according to any one of the above items (3) to (8). (10) In item (9), the sintering temperature is 1000 ° C or more and 1800
Non-aqueous secondary batteries that are below ℃. (11) The non-aqueous secondary battery according to (9) or (10), wherein a cooling temperature of the alloy after firing is 10 ° C./min or more. (12) A non-aqueous secondary battery in which the silicon compound according to item (1) is silicon obtained by removing a metal from a metal silicide. (13) A non-aqueous secondary battery in which the metal silicide according to (12) is lithium silicide. (14) A nonaqueous secondary battery according to item (13), wherein the lithium silicide has a lithium content of 100 to 420 atomic% with respect to silicon. (15) A non-aqueous secondary battery in which the silicon compound according to item (1) is silicon whose lithium has been removed by treating a lithium silicide with an alcohol dehydrated. (16) A non-aqueous secondary battery in which the silicon compound according to item (1) is adhered to a ceramic that does not react with lithium. (17) The ceramic described in (16) is made of Al ₂ O ₃ or Si.
A non-aqueous secondary battery that is at least one selected from O ₂ , TiO ₂ , SiC, and Si ₃ N ₄ . (18) A non-aqueous secondary battery in which the ceramic according to item (17) is SiO ₂ . (19) The SiO ₂ described in the item (18) is a colloidal Si.
A non-aqueous secondary battery that is O ₂ . (20) A nonaqueous secondary battery in which the weight ratio of the ceramic to the silicon compound according to any one of (16) to (19) is 2 to 50%. (21) A method for producing a nonaqueous secondary battery, wherein the method for attaching the ceramic to the silicon compound according to any one of the above (16) to (20) includes a step of heating at 300 ° C to 1600 ° C. (22) A non-aqueous secondary battery in which the silicon compound according to (1) is coated with at least one metal. (23) A method for producing a non-aqueous secondary battery, wherein the method of coating with the metal of item (22) is at least one selected from electroless plating, vapor deposition, sputtering, chemical vapor deposition, and metal pressing. . (24) The metal to be coated in the items (22) and (23) is Ni, C
u, Ag, Co, Fe, Cr, W, Ti, Au, Pt,
A non-aqueous secondary battery comprising at least one of Pd, Sn, and Zn. (25) The metal to be covered in the paragraphs (22) and (23) is Ni, C
Non-aqueous secondary batteries that are at least one of u and Ag. (26) A non-aqueous secondary battery in which the specific conductivity of the silicon compound coated with the metal according to the above items (22) to (25) is at least 10 times the specific conductivity of the non-coated silicon compound. (27) A non-aqueous secondary battery in which the metal coverage of items (22) to (26) is 1 to 80 atomic% with respect to silicon. (28) A non-aqueous secondary battery in which the silicon compound according to item (1) is partially covered with a thermoplastic resin in advance. (29) The non-aqueous secondary battery according to item (28), wherein the method of partially covering with a thermoplastic resin in advance includes a step of dissolving or dispersing the thermoplastic resin in a solvent, and then mixing and kneading a silicon compound. Manufacturing method. (30) A non-aqueous secondary battery in which the thermoplastic resin of (28) and (29) is at least one selected from polyvinylidene fluoride and polytetrafluoroethylene. (31) A nonaqueous secondary battery in which the weight ratio of the thermoplastic resin to the silicon compound according to any one of the above items (28) to (30) is 2 to 30%. (32) The covering rate of the thermoplastic resin of the items (28) to (31) is 5 to 5.
95% non-aqueous secondary battery. (33) A non-aqueous secondary battery in which carbon coexists in a weight ratio of 5 to 1900% with respect to the silicon compound of item (1). (34) A non-aqueous secondary battery in which carbon coexists in a weight ratio of 5 to 400% with respect to the silicon compound of item (1). (35) A non-aqueous secondary battery in which the carbon of (33) and (34) is scaly natural graphite. (36) A nonaqueous secondary battery in which the charge / discharge range of the silicon compound according to the above item (1) is represented by Li _x Si, where x is in the range of 0 to 4.2, as an equivalent ratio of lithium inserted and released into silicon . (37) The charge / discharge range of the silicon compound of the item (1) is Li _x
A non-aqueous secondary battery in which x is in the range of 0 to 3.7 when represented by Si. (38) A non-aqueous secondary battery in which charging of the silicon compound according to item (1) is terminated within a range of 0.1% or more and 10% or less of a one-hour rate current. (39) A non-aqueous secondary battery in which the charging described in (38) is completed within 15 minutes to 10 hours. (40) The positive electrode active material of item (1) is Li _y MO ₂ (M = C
o, at least one of Ni, Fe, and Mn y = 0 to 1.
2) or Li _z N ₂ O ₄ (N = Mnz =
Non-aqueous secondary batteries using at least one of the materials having a spinel structure represented by (0-2). Positive electrode active material (41) in claim 1 is _{Li y M a D 1-a} O
₂ (M = at least one of Co, Ni, Fe, Mn, D
= Co, Ni, Fe, Mn, Al, Zn, Cu, Mo,
Ag, W, Ga, In, Sn, Pb, Sb, Sr, B,
At least one kind other than M in P, y = 0 to 1.2, a
= 0.5-1), or Li _z (N _b E _1-b )
₂ O ₄ (N = Mn, E = Co, Ni, Fe, Al, Z
n, Cu, Mo, Ag, W, Ga, In, Sn, Pb,
At least one of Sb, Sr, B and P, b = 0.2 to
1, a non-aqueous secondary battery using at least one kind of material having a spinel structure represented by z = 0 to 2). (42) A non-aqueous secondary battery in which the average particle size of silicon used in items (3) to (39) is 0.01 to 50 μm. (43) A nonaqueous secondary battery in which the average particle size of silicon used in the items (3) to (39) is 0.05 to 5 μm. (44) A non-aqueous secondary battery in which the silicon according to item (42) or (43) is at least one selected from the group consisting of a silicon simple substance, a silicon alloy, and a silicide capable of reacting with lithium. (45) The alloy according to any one of Items (3) to (11) is changed to
(21) A non-aqueous secondary battery which is an alloy to which the ceramic is attached. (46) The alloy according to any one of Items (3) to (11) is changed to
A non-aqueous secondary battery comprising the metal-coated alloy of (27). (47) A non-aqueous secondary battery in which the alloy according to item (45) is an alloy coated with the metal according to items (22) to (27). (48) A non-aqueous secondary battery in which the alloy described in (46) is an alloy to which the ceramic of (16) to (21) is adhered. (49) The alloy according to any one of Items (3) to (11) is changed from Item (28) to Item (28).
(32) A non-aqueous secondary battery which is an alloy coated with a thermoplastic resin. (50) A non-aqueous secondary battery obtained by plating the material of item (49) with the items of items (22) to (27). (51) A non-aqueous secondary battery in which the material of (45) to (48) is a material coated with the thermoplastic resin of (28) to (32). (52) A nonaqueous secondary battery in which the material of the item (45) is a material obtained by coating the thermoplastic resin of the items (28) to (32) and then coating the metal of the items (22) to (27). (53) The alloy described in (3) to (11) is changed to
(35) A non-aqueous secondary battery which is a material coexisting with carbon. (54) The materials described in (45) to (52) are different from (33) to (33).
(35) A non-aqueous secondary battery which is a material coexisting with carbon. (55) The negative electrode according to any one of Items (3) to (11) is replaced with the negative electrode according to Items (36) to (36).
A non-aqueous secondary battery used in the charge / discharge range according to (39). (56) The materials described in (45) to (54) are replaced with the materials described in (36) to (36).
A non-aqueous secondary battery used in the charge / discharge range according to (39). (57) A non-aqueous secondary battery using the alloy according to (3) to (11) as a negative electrode material and the compound according to (40) or (41) as a positive electrode active material. (58) A non-aqueous secondary battery using the material according to items (42) to (54) as a negative electrode material and the compound according to item (40) or (41) as a positive electrode active material. (59) The silicon according to any one of (12) to (15) is selected from
(21) A non-aqueous secondary battery comprising silicon to which the ceramic is adhered. (60) The silicon according to any one of Items (12) to (15) is selected from
(27) A non-aqueous secondary battery comprising metal-coated silicon. (61) A non-aqueous secondary battery in which the material of the item (59) is a material coated with the metal of the items (22) to (27). (62) A non-aqueous secondary battery in which the material of the item (60) is a material to which the ceramic of the items (16) to (21) is adhered. (63) The silicon according to any one of Items (12) to (15) is changed to
(32) The non-aqueous secondary battery which is silicon coated with the thermoplastic resin. (64) A non-aqueous secondary battery, which is a material obtained by coating the material according to item (63) with the metal according to items (22) to (27). (65) A non-aqueous secondary battery in which the material of (59) to (62) is a material coated with the thermoplastic resin of (28) to (32). (66) A nonaqueous secondary battery in which the material of the item (59) is a material obtained by coating the thermoplastic resin of the items (28) to (32) and then coating the metal of the items (22) to (27). (67) The silicon according to any one of (12) to (15) is selected from
(35) A non-aqueous secondary battery which is a material coexisting with carbon. (68) The material according to any one of Items (59) to (66) is
(35) A non-aqueous secondary battery which is a material coexisting with carbon. (69) The negative electrode according to any one of Items (12) to (15) is replaced with the negative electrode according to Items (36) to (36).
A non-aqueous secondary battery used in the charge / discharge range according to (39). (70) The material described in (59) to (69) is replaced with (36) to (36).
A non-aqueous secondary battery used in the charge / discharge range according to (39). (71) A nonaqueous secondary battery using the silicon according to items (12) to (15) as the negative electrode material and the compound according to item (40) or (41) as the positive electrode active material. (72) A non-aqueous secondary battery using the material according to any one of Items (59) to (68) as a negative electrode material and the compound according to Item (40) or (41) as a positive electrode active material. (73) A nonaqueous secondary battery in which the silicon compound according to any one of Items (16) to (21) is silicon coated with the metal according to Items (22) to (27). (74) A non-aqueous secondary battery in which the silicon compound according to any one of Items (16) to (21) is a silicon compound coated with the thermoplastic resin according to any one of Items (28) to (32). (75) A non-aqueous secondary battery in which the material of the item (73) is a material coated with the thermoplastic resin of the items (28) to (32). (76) A nonaqueous secondary battery in which the material described in (75) is a material coated with the metal according to (22) to (27). (77) The silicon compound according to any one of (16) to (21) is (3)
3) A non-aqueous secondary battery which is a silicon compound having carbon coexisting therein. (78) The materials described in (73) to (77) are (33) to (3)
5) A non-aqueous secondary battery that is a material coexisting with carbon. (79) A non-aqueous secondary battery using the silicon compound according to any one of (16) to (21) in the charge / discharge method according to any one of (36) to (39). (80) The materials described in (73) to (78) are replaced with the materials described in (36) to (36).
A non-aqueous secondary battery used in the charge / discharge method according to (39). (81) A nonaqueous secondary battery using the silicon compound according to any one of Items (16) to (21) as a negative electrode material and the compound according to Item (40) or (41) as a positive electrode active material. (82) A non-aqueous secondary battery using the material described in any one of Items (73) to (78) as a negative electrode material and the compound described in Item (40) or (41) as a positive electrode active material. (83) The material described in any one of Items (22) to (27) is changed to
A non-aqueous secondary battery which is a material to which the ceramic according to (21) is attached. (84) The materials described in (22) to (27) are changed to
A non-aqueous secondary battery which is a material coated with the thermoplastic resin according to (32). (85) A non-aqueous secondary battery in which the material of the item (83) is a material coated with the thermoplastic resin according to the items (28) to (32). (86) The material described in (22) to (27) is replaced with (33) to (33).
(35) A non-aqueous secondary battery which is a material coexisting with carbon. (87) The material described in any one of Items (83) to (85) is
(35) A non-aqueous secondary battery which is a material coexisting with carbon. (88) The material described in (22) to (27) is replaced with (33) to (33).
(35) A non-aqueous secondary battery which is a material coexisting with carbon. (89) The materials described in (22) to (27) are replaced with (36) to (36).
A non-aqueous secondary battery used in the charge / discharge method according to (39). (90) The materials described in (83) to (88) are replaced with the materials described in (36) to (36).
A non-aqueous secondary battery used in the charge / discharge method according to (39). (91) The material according to any one of Items (22) to (27) as a negative electrode material,
A non-aqueous secondary battery using the compound described in (40) or (41) as a positive electrode active material. (92) The material according to any one of Items (81) to (88) as a negative electrode material,
A non-aqueous secondary battery using the compound described in (40) or (41) as a positive electrode active material. (93) The materials described in (28) to (32) are (16) to (2)
Non-aqueous secondary battery which is a material with ceramic attached to 1). (94) The material described in (28) to (32) is (22) to (2)
A non-aqueous secondary battery which is a material coated with a metal according to 7). (95) A nonaqueous secondary battery in which the material described in (93) is a material coated with the metal described in (22) to (27). (96) The material according to any one of Items (28) to (32) is changed to
A non-aqueous secondary battery which is a material coexisting with carbon according to (35). (97) A non-aqueous secondary battery in which the material described in (93) is a material coexisting with carbon according to (33) to (35). (98) A non-aqueous secondary battery in which the material described in (94) is a material coexisting with carbon according to (33) to (35). (99) The materials described in (28) to (32) are replaced with the materials described in (36) to (36).
A non-aqueous secondary battery used in the charge / discharge method according to (39). (100) The materials described in (93) to (98) are replaced with the materials described in (36) to (36).
A non-aqueous secondary battery used in the charge / discharge method according to (39). (101) The material according to any one of Items (28) to (32) as a negative electrode material,
A non-aqueous secondary battery using the compound described in (40) or (41) as a positive electrode active material. (102) The material according to any one of Items (93) to (98) as a negative electrode material,
A non-aqueous secondary battery using the compound described in (40) or (41) as a positive electrode active material. (103) The material according to any one of Items (33) to (35) as a negative electrode material,
A non-aqueous secondary battery using the compound according to (40) or (41) as a positive electrode active material. (104) The materials described in (33) to (35) are replaced with the materials described in (36) to (36).
A non-aqueous secondary battery used in the charge / discharge method according to (39). (105) The materials described in (42) to (44) are replaced with (36) to (36).
A non-aqueous secondary battery used in the charge / discharge method according to (39).

The positive electrode (or negative electrode) used in the present invention
Applies the positive electrode mixture (or the negative electrode mixture) on the current collector,
It can be made by molding. The positive electrode mixture (or negative electrode mixture) may include a conductive agent, a binder, a dispersant, a filler, an ionic conductive agent, a pressure enhancer, and various additives in addition to the positive electrode active material (or the negative electrode material). it can. These electrodes may be disk-shaped or plate-shaped, but are preferably in the form of a flexible sheet.

Hereinafter, the structure and material of the present invention will be described in detail. The compound containing a silicon atom capable of inserting and releasing lithium used in the negative electrode material of the present invention means a simple substance of silicon, a silicon alloy, or a silicide. As the silicon compound, any of single crystal, polycrystal and amorphous can be used. The purity of the simple substance is preferably 85% by weight or more, and particularly preferably 95% by weight or more. Furthermore, 99% by weight or more is particularly preferable. As impurities, mainly, Fe, A
1, Ca, Mn, Mg, Ni, Cr and the like. Their content is 0-0.5% by weight. The average particle size of the silicon compound is preferably 0.01 to 50 μm.
In particular, 0.02 to 30 μm is preferable. In addition, 0.0
5-5 μm is preferred. It is well known that the surface of silicon is covered with silicon dioxide, and is considered to also serve as an ion conductive film.

The silicon alloy suppresses pulverization due to expansion and contraction of silicon generated when lithium is inserted and released,
It is considered to be effective in improving the low conductivity of silicon. As the alloy, an alloy with an alkaline earth metal, a transition metal or a metalloid is preferable. Particularly, a solid solution alloy or a eutectic alloy is preferable. A solid solution alloy is an alloy that forms a solid solution. For example, a Ge alloy is a solid solution alloy. A eutectic alloy is an alloy that eutectic in any proportion with silicon, but the solid obtained upon cooling is a mixture of silicon and metal. Be, Ag, Al, Au, Cd, Ga, In,
Sb, Sn, and Zn form a eutectic alloy. Among these, Ge, Be, Ag, Al, Au, Cd, Ga, I
An alloy of n, Sb, Sn, and Zn is more preferable. Also, two or more of these alloys are preferable. Especially, Ge, A
An alloy containing g, Al, Cd, In, Sb, Sn, and Zn is preferable. The mixing ratio of these alloys is preferably 5 to 90% by weight based on silicon. Especially, 10 to 80% by weight
Is preferred. Furthermore, 20 to 60% by weight is particularly preferred. . In addition to eutectic alloys, Mg, Fe, Co, Ni,
It may include Ti, Mo, and W. The content of these metals is preferably from 0 to 20% by weight. The mixing ratio of metals other than silicon is not particularly limited. In this case, the electrical conductivity is improved, but in terms of battery performance, in particular, discharge capacity, high rate characteristics, and cycle life, the specific conductivity may be 10 times or more that of silicon or a silicon compound before alloying. preferable.

As a method for synthesizing the alloy, a firing method and a mechanical milling method are used. As a firing method, a raw material metal is mixed, transferred to a crucible, and placed in an inert gas for 5 minutes.
The temperature is raised at a temperature rising rate of -100 ° C / min.
To 1700 ° C. for 10 minutes to 24 hours, particularly preferably 30
Keep for 5 minutes to 5 hours and cool at a rate of 10 ° C./min or more. In particular, it is preferable to cool at 100 ° C./min or more. As the inert gas, it is preferable to use a gas such as argon, nitrogen, or hydrogen alone or as a mixture. After cooling,
Annealing is preferred. As the annealing conditions,
In an inert gas, the temperature is preferably in a range from 200 ° C. to a temperature at which some alloys do not melt.

[0010] As the mechanical milling method, a method of pulverizing a plurality of metals to ultra fineness using a pulverizer such as a ball mill, a planetary ball mill, and a vibration mill is used. It is preferable to fill the inside of the cell of the mill with an inert gas, an inert liquid, a reducing gas, or a reducing liquid. As the inert gas, it is preferable to use a gas such as argon, nitrogen, or hydrogen alone or as a mixture. As the inert liquid, deoxygenated water, alcohol, or the like is used. As the reducing gas, ammonia, sulfur dioxide, or the like is used. As the reducing liquid, an aqueous solution containing sodium sulfite, sodium thiosulfate, hydroxylamine, hydroquinone, or the like, or a dimethyl sulfoxide solution can be used. Pulverization with an inert gas is particularly preferred.
The milling time is preferably from 1 hour to 48 hours.

The average particle size of the alloy is 0.01 to 40 μm.
m is preferred. In particular, 0.02 to 20 μm is preferable,
Further, 0.03 to 5 μm is particularly preferable. As a grinding method, a vibration mill, a ball mill, a planetary ball mill, a jet mill, and an automatic mortar are used. Grinding time is 1 minute ~
One hour is preferred. As a grinding atmosphere, the method described in the section on mechanical milling is used.

[0012] Silicide refers to a compound of silicon and a metal. As silicides, CaSi, CaSi ₂ , Mg ₂ S
i, BaSi ₂ , SrSi ₂ , Cu ₅ Si, FeSi, F
eSi ₂ , CoSi ₂ , Ni ₂ Si, NiSi ₂ , MnS
i, MnSi ₂ , MoSi ₂ , CrSi ₂ , TiSi ₂ , T
i ₅ Si ₃ , Cr ₃ Si, NbSi ₂ , NdSi ₂ , CeS
i ₂ , SmSi ₂ , DySi ₂ , ZrSi ₂ , WSi ₂ , W5
_{Si3, TaSi 2, Ta 5 Si} 3, TmSi 2, TbS
i ₂ , YbSi ₂ , YSi ₂ , YSi ₂ , ErSi, ErS
i ₂ , GdSi ₂ , PtSi, V ₃ Si, VSi ₂ , HfS
i ₂ , PdSi, PrSi ₂ , HoSi ₂ , EuSi ₂ , L
aSi, RuSi, ReSi, RhSi and the like are used.

As the silicon compound, it is preferable to use silicon obtained by removing a metal from a metal silicide. Examples of the shape of the silicon include porous particles having a particle size of 1 μm or less, and particles having fine secondary particles aggregated to form porous secondary particles. The reason that the cycle life is improved by using silicon is considered to be that it is difficult to pulverize. The metal of the metal silicide is an alkali metal,
Preferably, it is an alkaline earth metal. Above all, L
Preferably, i, Ca, and Mg are used. In particular, Li is preferable. The average particle size of the metal silicide is 0.01
３００300 μm, preferably 0.01-50 μm
m is more preferred, and 0.01 to 10 μm is most preferred. The lithium content of the lithium silicide is preferably 100 to 420 mol% based on silicon. In particular, 200
~ 420 mol% is preferred. In the method of removing an alkali metal or an alkaline earth metal from a silicide of an alkali metal or an alkaline earth metal, it is preferable to perform treatment with a solvent that reacts with the alkali metal or the alkaline earth metal. As the solvent, water and alcohols are preferable. In the case of lithium silicide, it is preferable to use degassed and dehydrated alcohols since oxidation of silicon during the reaction can be suppressed. As the degree of dehydration, the residual water amount is preferably 1000 ppm or less, preferably 200 ppm or less, and 50 ppm or less.
The following are most preferred. As a method of deaeration and dehydration,
Bubbling with an inert gas such as argon while refluxing the alcohol may be mentioned. As the type of alcohol, methyl alcohol, ethyl alcohol, 1-
Preferred are propyl alcohol, 2-propyl alcohol, 1-butyl alcohol, 2-butyl alcohol, t-butyl alcohol, 1-pentyl alcohol, 2-pentyl alcohol, and 3-pentyl alcohol. In particular,
1-propyl alcohol, 2-propyl alcohol, 1
-Butyl alcohol, 2-butyl alcohol and t-butyl alcohol are preferred. For removing Ca and Mg, water is preferable. It is more preferable to use a pH buffer that keeps the pH around neutral. The amount of the solvent may be at least the reaction equivalent, but is particularly preferably about 10 times. The reaction temperature is not particularly limited, but is preferably room temperature or lower in order to allow the reaction to proceed mildly and uniformly.

It is preferable that the silicon powder remaining after the reaction is removed by filtration or decantation and then washed. As the cleaning liquid, the above-mentioned water and alcohols are preferable. The powder thus obtained preferably has a residual metal content of 1% by weight or less, more preferably 0.1% by weight or less. In order to reduce the amount of residual metal, it is preferable to reduce the particle size of the silicide during the reaction. Specifically, 0.01 to 300 μm is preferable, 0.01 to 50 μm is more preferable, and 0.01 to 300 μm is preferable.
-10 μm is most preferred. As another method, it is also preferable to pulverize the powder obtained after completion of the reaction to reduce the particle size, and then re-inject the powder into the reaction solvent. It is also preferable to repeat the above-mentioned pulverization and reaction as required. It is preferable to coat the silicon powder obtained in this manner with a metal described below, since the discharge capacity and cycle life can be further improved.

[0015] It is considered that the ceramic adhered to the silicon compound is effective in suppressing the pulverization of silicon. As the ceramic, a compound that does not basically react with lithium is preferable. In particular, Al ₂ O ₃ , SiO ₂ , TiO ₂ , Si
C and Si ₃ N ₄ are preferred. As a method for attaching silicon and ceramic, mixing, heating, vapor deposition, and CVD are used, and particularly, a combination of mixing and heating is preferable. In particular, after a silicon is dispersed and mixed with a colloidal solution (colloidal silica) of Al ₂ O ₃ or SiO ₂ , the mixture is heated and the solid solution is pulverized to obtain a deposit of silicon and Al ₂ O ₃ or SiO _2. be able to. In this case, the Al ₂ O ₃ and SiO ₂ deposits, or as Al ₂ O ₃ and the surface of SiO ₂ or the like is covered with the silicon powder, trapped inside the mass, such as Al ₂ O ₃ or SiO ₂ Or that the silicon surface is covered with them. Mixing and dispersion can be achieved by mechanical stirring, ultrasonic waves, and kneading. Heating is preferably performed in an inert gas at a temperature in the range of 300 ° C to 1600 ° C, particularly, 400 ° C to 1500 ° C, and more preferably 500 ° C to
1300 ° C. is particularly preferred. Heating time is 0.5 to 24
Time is preferred. Inert gases include argon, nitrogen and hydrogen. These mixed gases are also used. As a pulverizing method, a well-known method such as a ball mill, a vibration mill, a planetary ball mill, a jet mill, and an automatic mortar is used. The environment described in mechanical milling is also preferable for this grinding,
In particular, it is preferably performed in an inert gas. The mixing ratio of the ceramic to silicon is preferably in the range of 2 to 50% by weight, and particularly preferably 3 to 40%. The average particle size determined from electron microscopic observation of silicon is 0.01
４０40 μm is preferred. In particular, it is preferably from 0.5 to 20 μm, and more preferably from 1 to 10 μm.

The metal coating of the silicon compound of the present invention includes electroplating, displacement plating, electroless plating, resistance heating vapor deposition, electron beam vapor deposition, cluster ion vapor deposition, etc., sputtering, chemical vapor deposition, and the like. This can be achieved by a phase growth method (CVD method). In particular, an electroless plating method, a resistance heating evaporation method, an electron beam evaporation method, an evaporation method such as a cluster ion evaporation method, a sputtering method, and a CVD method are preferable. In addition, a metal pressing method using a high-speed shearing mill, a stamp mill, or a roll mill is used. Above all,
Electroless plating is particularly preferred. The electroless plating method is described in “Electroless Plating Basics and Applications”, edited by Electroplating Research Group, published by Nikkan Kogyo Shimbun (1994). The reducing agent is preferably a phosphinate, phosphonate, borohydride, aldehyde, saccharide, amine, or metal salt. Preferred are sodium hydrogen phosphinate, sodium hydrogen phosphonate, sodium borohydride, dimethylamine borane, formaldehyde, sucrose, dextrin, hydroxylamine, hydrazine, ascorbic acid, and titanium chloride. The plating solution preferably contains a pH adjuster and a complexing agent in addition to the reducing agent. Also for these, the compounds described in the above “Electroless Plating Basics and Applications” are used. The plating solution composition is also described in the above book. The concentration of the reducing agent is preferably from 10 to 500 g per liter of water. The pH of the plating solution is not particularly limited, but is preferably 4 to 13. Liquid temperature is 1
0 ° C to 100 ° C is preferred, but in particular, 20 ° C to 95 ° C
But this is good. In addition to the plating bath, an activation bath composed of an aqueous solution of SnCl ₂ hydrochloric acid and a nucleation bath composed of an aqueous solution of PdCl ₂ hydrochloric acid are used. Further, a filtration step, a washing step, a pulverizing step,
A drying step is used.

The silicon compound to be coated may be in any form such as powder, lump, and plate.
The metal to be coated is not particularly limited as long as it is a metal having high conductivity. In particular, Ni, Cu, Ag, Co, Fe, Cr,
W, Ti, Au, Pt, Pd, Sn and Zn are preferred.
In particular, Ni, Cu, Ag, Co, Fe, Cr, Au,
Pt, Pd, Sn, and Zn are preferable, and Ni, C
u, Ag, Pd, Sn, and Zn are particularly preferred. The amount of the metal to be coated is not particularly limited, but it is preferable that the metal is coated so that the specific conductivity is at least 10 times the specific conductivity of the silicon compound as the base. The coating amount of the metal is preferably from 1 to 80% by weight, particularly preferably from 1 to 50% by weight, based on silicon.
Further, 1 to 30% by weight is particularly preferable.

The silicon compound used in the present invention is preferably partially coated with a synthetic resin in advance from the viewpoint of improving cycle life. It is considered that the reason why the cycle life is improved is that the pulverization of the silicon compound accompanying lithium insertion is suppressed. Synthetic resins are roughly classified into thermoplastic resins and thermosetting resins, and thermoplastic resins are more preferable for improving cycle life. The thermoplastic resin is a fluorine-containing polymer compound, an imide polymer, a vinyl polymer, an acrylate polymer, an ester polymer,
Polyacrylonitrile and the like are used. In particular, the thermoplastic resin is preferably a resin that does not easily swell in the electrolytic solution. Specific examples include water-soluble polymers such as polyacrylic acid, sodium polyacrylate, polyvinyl phenol, polyvinyl methyl ether, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, polyhydroxy (meth) acrylate, and styrene-maleic acid copolymer; Polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, polyvinyl acetal resin, methyl methacrylate, 2
-(Meth) acrylate copolymer containing (meth) acrylate such as ethylhexyl acrylate, (meth) acrylate-acrylonitrile copolymer, polyvinyl ester copolymer containing vinyl ester such as vinyl acetate , Styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, polybutadiene, neoprene rubber, fluoro rubber, polyethylene oxide, polyester polyurethane resin, polyether polyurethane resin, polycarbonate polyurethane resin, emulsion of polyester resin, phenol resin, epoxy resin, etc. (Latex) or suspension. In particular, polyacrylate latex, carboxymethylcellulose, polytetrafluoroethylene, and polyvinylidene fluoride are exemplified. These compounds can be used alone or as a mixture. Among these compounds, fluorine-containing polymer compounds are preferred. Among them, polytetrafluoroethylene and polyvinylidene fluoride are preferable. As a method of coating in advance, a solution is dissolved or dispersed in a synthetic resin solvent, and a silicon compound is mixed and kneaded in the solution.
A method of drying the solution and pulverizing the obtained solid is preferable. Any solvent can be used as long as it can dissolve the synthetic resin. In the case of polyvinylidene fluoride, N-methyl-2-pyrrolidone or dimethylformamide is preferable. As another method of coating in advance, it is also preferable to uniformly mix the synthetic resin powder and the silicon compound powder and then heat to melt the thermoplastic resin and then pulverize the obtained solid. When the obtained solid is pulverized, it is preferable to pulverize it in an atmosphere of an inert gas such as argon in order to suppress a side reaction such as oxidation of a silicon compound. The use of the above-described thermoplastic resin as a binder in forming a negative electrode mixture layer is generally known. Whereas the method of use as a binder is a method of uniformly mixing and using an active material, a conductive agent, and the like, the method of use as a coating agent of the present invention localizes a thermoplastic resin on the surface of an active material. Different in that. It has been conventionally known that the cycle life is improved by increasing the amount of the thermoplastic resin used as a binder, but the method of coating the active material surface of the present invention is more effective in improving the cycle life. Is big.

The amount of the synthetic resin used relative to the silicon compound is preferably from 2 to 30% by weight. Especially 3-20
% By weight is preferred. In the present invention, it is preferable that the synthetic resin is partially covered. Coverage is 5-95%
Is preferred, and particularly preferably 5 to 90%. Here, the coverage is defined as a percentage of the area of the portion coated with the thermoplastic resin with respect to the total surface area of the silicon compound particles. Since a thermoplastic resin is generally insulative, it is preferable to use a means for improving conductivity when coating the surface of the silicon compound. As a means for improving the conductivity, known methods such as coexistence with carbon fine particles, coexistence with metal fine particles, and combined use of metal plating can be used. The average size of the coated particles is between 0.01 μm and 40 μm
Is preferred. In particular, it is preferably from 0.03 to 5 μm. It is preferable to use a dispersion medium in which the synthetic resin does not dissolve as a dispersion medium used when preparing the negative electrode mixture by mixing the particles coated with the synthetic resin with a conductive agent and a binder. For example, when coated with polyvinylidene fluoride, water is preferably used as a dispersion medium for preparing the negative electrode mixture. The above-mentioned method is used for the pulverizing method and its environment. In order to impart electron conductivity, it is preferable to use a metal coating method in combination.

In the present invention, it is preferable to use a mixture of a silicon compound and a carbonaceous compound. As the carbonaceous material, a material used as a conductive agent or a negative electrode material is used. Examples of the carbonaceous material include a non-graphitizable carbon material and a graphite-based carbon material. Specifically, Japanese Patent Application Laid-Open No. 62-122066
, Japanese Unexamined Patent Publications Nos. 2-66856 and 3-245473, and carbon materials having plane spacing, density, and crystallite size, and natural graphite and artificial materials described in Japanese Patent Laid-Open No. 5-290844. A mixture of graphite, JP-A-63-24555,
JP-A-63-13282, JP-A-63-58763, and the vapor-grown carbon material described in JP-A-6-212617, and the non-graphitizable carbon described in JP-A-5-182664 were used.
A material which is heated and fired at a temperature exceeding 400 ° C. and has X-ray diffraction peaks corresponding to a plurality of 002 planes, JP-A-5-307957 and JP-A-5-307958.
, A mesophase carbon material synthesized by pitch firing described in JP-A-7-85862 and JP-A-8-315820, a graphite having a coating layer described in JP-A-6-84516, and various granular materials And carbon materials such as microspheres, flat bodies, microfibers, whisker-shaped carbon materials, phenol resins, acrylonitrile resins, fired products of furfuryl alcohol resins, and polyacene materials containing hydrogen atoms. Further, specific examples of the conductive agent include flake graphite, flake graphite, natural graphite such as earth graphite, petroleum coke, coal coke, celluloses, sugars, high-temperature fired bodies such as mesophase pitch, vapor-grown graphite, etc. Carbon materials such as graphite such as artificial graphite, carbon black such as acetylene black, furnace black, ketjen black, channel black, lamp black, and thermal black, asphalt pitch, coal tar, activated carbon, meso fuse pitch, and polyacene. preferable. These may be used alone,
It may be used as a mixture.

[0021] In particular, carbon materials and various granular materials, microspheres, flat plates, and the like described in JP-A-5-182664 are disclosed.
A carbon material in the form of a fiber or whisker, a mesophase pitch, a fired body of a phenol resin or an acrylonitrile resin, and a polyacene material containing a hydrogen atom are preferable. Above all, flaky natural graphite is preferable because it strengthens the mixture film. The mixing ratio is 5 to silicon compound.
1900% by weight is preferred. In particular, 20 to 500% by weight is preferable. Furthermore, 30 to 400% by weight is preferable. Although various average particle sizes can be used for the carbonaceous material, 0.01 to 50 μm is preferable, 0.02 to 30 μm is more preferable, and 0.05 to 50 μm is preferable.
5 μm is most preferred.

As the conductive agent, other materials other than carbon can be used as described below. The charge / discharge range of the silicon compound negative electrode material is preferably x = 0 to 4.2 when the ratio of lithium and silicon atoms that can be inserted and released is represented by Li _x Si. As a result of intensive studies on improving the cycle life of silicon,
It was found that when x was kept in the range of 0 to 3.7, the cycle life was greatly improved. At the charge potential, with respect to the lithium metal counter electrode, at x = 4.2, including overvoltage,
0.0V, whereas at x = 3.7, about 0.05
V. At this time, the shape of the discharge curve changes,
A flat discharge curve is obtained around 0.5 V (body lithium metal) at 0 V charge turnback, whereas about 0.05 V or more, particularly at 0.08 V or more (x = 3.6), about 0.
A smooth curve with an average voltage at 4V is obtained. That is, the inventors have found a specific phenomenon that the discharge potential decreases as the charging end voltage is increased. In addition, they found a phenomenon in which the reversibility of the charge / discharge reaction also increased.

As the method of starting and stopping charging in the present invention, a method of combining an open circuit constant voltage, a closed circuit constant voltage, a current, a time, a combination of a large current charge and a small current charge, and the like are used.
It is preferable to set the current at the time of closed circuit constant voltage, and to set the charging time together. The constant voltage value is set in the above range. The current value is 0.1 to 1 of 1 hour rate current in the constant voltage region.
It is preferable to stop charging when the value falls within the range of 0%.

Although a method having the effect of improving the cycle life while maintaining a high capacity of the silicon compound has been individually described, a more preferred embodiment has been found to achieve a higher improvement effect by a combination of the above methods. .

In the present invention, as the negative electrode material, in addition to the silicon compound of the present invention, a carbonaceous material, an oxide material, a nitride material,
It can be combined with a compound capable of inserting and releasing lithium, such as a sulfide material, lithium metal, and lithium alloy.
Particularly when a transition metal oxide is used as the positive electrode material, it is used in combination with lithium metal or a lithium alloy.

As the cathode material used in the present invention, a transition metal oxide capable of inserting and releasing lithium is used.
Lithium-containing transition metal oxides are preferred. Preferably T
An oxide mainly containing lithium and at least one transition metal element selected from i, V, Cr, Mn, Fe, Co, Ni, Mo, and W, and having a molar ratio of lithium to the transition metal of 0.1. 3 to 2.2. More preferably, it is an oxide mainly containing lithium and at least one transition metal element selected from V, Cr, Mn, Fe, Co, and Ni, and the molar ratio of lithium to the transition metal is from 0.3 to 0.3. 2.2. In addition, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, S
i, P, B and the like may be contained. Among the positive electrode active materials described above, the general formula Li _x MO ₂ (M = Co, Ni, Fe,
At least one of Mn x = 0 to 1.2), or Li
_{y N 2 O 4 (N =} Mn y = 0~2) be at least one material having a spinel structure represented by preferred. Specifically, Li _x CoO ₂ , Li _x NiO ₂ , L
_{i x MnO 2, Li x Co} a Ni 1-a O 2, Li x Co b V
_1-b O _z , Li _x Co _b Fe _1-b O ₂ , Li _x Mn ₂ O ₄ , L
_{i x Mn c Co 2-c} O 4, Li x Mn c Ni 2-c O 4, Li x
_{Mn c V 2-c O 4} , Li x Mn c Fe 2-c O 4 ( wherein x =
0.02-1.2, a = 0.1-0.9, b = 0.8-
0.98, c = 1.6-1.96, z = 2.01-2.
3).

Further, the positive electrode active material is Li_yM_aD_1-aO_Two
(M = at least one of Co, Ni, Fe, Mn D =
Co, Ni, Fe, Mn, Al, Zn, Cu, Mo, A
g, W, Ga, In, Sn, Pb, Sb, Sr, B, P
At least one other than M y = 0 to 1.2, a =
0.5-1), or Li_z(N_bE_1-b)_Two
O_Four(N = Mn E = Co, Ni, Fe, Mn, Al,
Zn, Cu, Mo, Ag, W, Ga, In, Sn, P
b, Sb, Sr, B, and PE are at least one kind of b = 1 to b.
0.2 having a spinel structure represented by z = 0 to 2)
It is particularly preferred to use at least one of the materials. Most
Also preferred as the lithium-containing transition metal oxide is Li
_xCoO_Two, Li_xNiO_Two, Li_xMnO_Two, Li_xCo_aN
i_1-aO_Two, Li_xMn_TwoO_Four, Li_xCo _bV_1-bO_z
(X = 0.02 to 1.2, a = 0.1 to 0.9, b =
0.9 to 0.98, z = 2.01 to 2.3).
You. Note that the value of x is a value before the start of charge / discharge,
Increase or decrease. The positive electrode active material used in the present invention is lithium-ionized.
Method of mixing and firing the compound and transition metal compound, and solution reaction
Can be synthesized, but the firing method is particularly preferred.
No. Details of firing are described in JP-A-6-60,867.
Drop 35, described in JP-A-7-14,579, etc.
And these methods can be used. By firing
The obtained positive electrode active material is water, acidic aqueous solution, alkaline aqueous solution.
It may be used after washing with a liquid or an organic solvent. In addition,
Method for chemically inserting lithium ions into a transfer metal oxide
As lithium metal, lithium alloy or butyllithium
Synthesis by reacting a transition metal with a transition metal oxide
It may be a law.

The average particle size of the positive electrode active material used in the present invention is not particularly limited, but is preferably 0.1 to 50 μm. It is preferable that the volume of the particles of 0.5 to 30 μm is 95% or more. The volume occupied by the particle group having a particle size of 3 μm or less is 18% or less of the total volume, and 15 μm or more and 25 μm or more
More preferably, the volume occupied by the particle group of m or less is 18% or less of the total volume. No particular limitation is imposed on the specific surface area is preferably 0.01 to 50 m ² / g by the BET method, particularly preferably 0.2m ² / g~1m ² / g. Further, when 5 g of the positive electrode active material is dissolved in 100 ml of distilled water, the pH of the supernatant is preferably 7 or more and 12 or less.

When the positive electrode active material of the present invention is obtained by firing, the firing temperature is preferably 500 to 1500 ° C., more preferably 700 to 1200 ° C., and particularly preferably 750 to 1000 ° C. The firing time is preferably 4 to 30 hours, more preferably 6 to 20 hours, and particularly preferably 6 to 15 hours.

The conductive agent used in the mixture of the present invention may be any material as long as it does not cause a chemical change in the constructed battery. Specific examples include flake graphite, flake graphite, natural graphite such as earthy graphite, petroleum coke, coal coke, celluloses, sugars, high-temperature fired bodies such as mesophase pitch, and graphite such as artificial graphite such as vapor-grown graphite. , Carbon blacks such as acetylene black, furnace black, ketjen black, channel black, lamp black, and thermal black; asphalt pitch, coal tar, activated carbon, meso fuse pitch, carbon materials such as polyacene, and conductive materials such as metal fibers. Fibers, metal powders such as copper, nickel, aluminum, silver, etc.,
Conductive whiskers such as zinc oxide and potassium titanate;
Examples thereof include conductive metal oxides such as titanium oxide. In the case of graphite, it is preferable to use a plate-like graphite having an aspect ratio of 5 or more. Among these, graphite and carbon black are preferable, and the particle size is 0.01%.
The particle size is preferably not less than μm and not more than 20 μm, more preferably not less than 0.02 μm and not more than 10 μm. These may be used alone or in combination of two or more. When used together, it is preferable to use carbon blacks such as acetylene black and graphite particles of 1 to 15 μm in combination. The amount of the conductive agent added to the mixture layer is preferably 1 to 50% by weight based on the negative electrode material or the positive electrode material, and more preferably 2 to 3% by weight.
It is preferably 0% by weight. For carbon black and graphite, the content is particularly preferably 3 to 20% by weight.

In the present invention, a binder is used to hold the electrode mixture. Examples of the binder include polysaccharides, thermoplastic resins, and polymers having rubber elasticity. Preferred binders include starch, carboxymethyl cellulose, cellulose, diacetyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, sodium alginate, polyacrylic acid,
Water-soluble polymers such as sodium polyacrylate, polyvinylphenol, polyvinylmethylether, polyvinylalcohol, polyvinylpyrrolidone, polyacrylamide, polyhydroxy (meth) acrylate, styrene-maleic acid copolymer, polyvinyl chloride, polytetrafluoroethylene, Polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM),
(Meth) acrylate copolymer containing (meth) acrylate such as sulfonated EPDM, polyvinyl acetal resin, methyl methacrylate, 2-ethylhexyl acrylate, etc., (meth) acrylate-acrylonitrile copolymer, vinyl Polyvinyl ester copolymer containing vinyl ester such as acetate, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, polybutadiene, neoprene rubber, fluorine rubber, polyethylene oxide, polyester polyurethane resin, polyether polyurethane resin, polycarbonate polyurethane Resin, polyester resin,
An emulsion (latex) such as a phenol resin or an epoxy resin or a suspension can be used. In particular, polyacrylate latex, carboxymethylcellulose, polytetrafluoroethylene, and polyvinylidene fluoride are exemplified. As these binders, it is preferable to use those obtained by dispersing fine powder in water, and it is more preferable to use those in which the average size of the particles in the dispersion is 0.01 to 5 μm, and 0.05 to 1 μm. It is particularly preferred to use one. These binders can be used alone or as a mixture. If the amount of the binder is small, the holding power and cohesive strength of the electrode mixture are weak. If it is too large, the electrode volume increases and the capacity per unit volume or unit weight of the electrode decreases. For these reasons, the amount of binder added is 1
It is preferably from 30 to 30% by weight, particularly preferably from 2 to 10% by weight.

As the filler, any fibrous material that does not cause a chemical change in the constructed battery can be used. Usually, fibers such as olefin-based polymers such as polypropylene and polyethylene, glass, and carbon are used. Although the amount of the filler is not particularly limited,
30% by weight is preferred. As the ionic conductive agent, those known as inorganic and organic solid electrolytes can be used, and the details are described in the section of the electrolytic solution. The pressure booster is a compound for raising the internal pressure of the battery, and a carbonate such as lithium carbonate is a typical example.

In the current collector which can be used in the present invention, the positive electrode is aluminum, stainless steel, nickel, titanium or an alloy thereof, and the negative electrode is copper, stainless steel, nickel,
Titanium or their alloys. The form of the current collector is foil, expanded metal, punched metal, or wire mesh. In particular, an aluminum foil is preferable for the positive electrode, and a copper foil is preferable for the negative electrode. 7 μm to 100 μm as foil thickness
Is preferably, more preferably, 7 μm to 50 μm, and particularly preferably, 7 μm to 20 μm. Expanded metal, punching metal, wire mesh thickness is 7
μm to 200 μm, more preferably 7 μm
To 150 μm, particularly preferably 7 μm to 100 μm.
m. The purity of the current collector is preferably 98% or more, more preferably 99% or more, and particularly preferably 99.3% or more. The surface of the current collector may be washed with an acid, an alkali, an organic solvent, or the like.

The current collector is more preferably formed by forming a metal layer on both sides of a plastic sheet in order to reduce the thickness. The plastic is preferably excellent in stretchability and heat resistance, and is, for example, polyethylene terephthalate. Metals alone have little elasticity and are vulnerable to external forces. If a metal layer is formed on plastic, it will be resistant to impact. More specifically, the current collector may be a composite current collector in which a base material such as a synthetic resin film or paper is coated with an electron conductive material. As a synthetic resin film as a base material,
Examples include fluororesin, polyethylene terephthalate, polycarbonate, polyvinyl chloride, polystyrene, polyethylene, polypropylene, polyimide, polyamide, cellulose dielectric, and polysulfone. Examples of the electron conductive material that coats the base material include carbonaceous materials such as graphite and carbon black, metal elements such as aluminum, copper, nickel, chromium, iron, molybdenum, gold, and silver and alloys thereof. it can. Particularly preferred electron conductive materials are metals, such as aluminum, copper, nickel and stainless steel. The composite current collector may be in a form in which a base sheet and a metal sheet are laminated, or a metal layer may be formed by vapor deposition or the like.

Next, the structure of the positive and negative electrodes in the present invention will be described. The positive and negative electrodes preferably have a form in which an electrode mixture is applied to both surfaces of a current collector. In this case, the number of layers per side may be one or two or more. When the number of layers per side is two or more, the number of layers containing the positive electrode active material (or the negative electrode material) may be two or more. More preferably, the layer containing the positive electrode active material (or the negative electrode material) and the positive electrode active material (or the negative electrode material)
This is a case where it is composed of a layer containing no. The layer containing no positive electrode active material (or negative electrode material) includes a protective layer for protecting the layer containing the positive electrode active material (or negative electrode material), and a layer between the divided positive electrode active material (or negative electrode material) containing layer. Layer, positive electrode active material (or negative electrode material)
There is an undercoat layer between the containing layer and the current collector, and these are collectively referred to as an auxiliary layer in the present invention.

Preferably, the protective layer is on both the positive and negative electrodes or on either the positive or negative electrode. In the negative electrode, when lithium is inserted into the negative electrode material in the battery, the negative electrode preferably has a form having a protective layer. The protective layer is composed of at least one layer, and may be composed of a plurality of layers of the same type or different types. Further, the current collector may have a form in which the protective layer is provided only on one side of the mixture layer on both sides. These protective layers are composed of water-insoluble particles, a binder and the like. As the binder, the binder used when forming the above-mentioned electrode mixture can be used. As the water-insoluble particles, various kinds of conductive particles, organic and inorganic particles having substantially no conductivity can be used. The solubility of the water-insoluble particles in water is 100 ppm or less, and preferably the insoluble particles are insoluble. 2.5% by weight of particles contained in the protective layer
Not less than 96% by weight, preferably not less than 5% by weight and 95% by weight.
% By weight or less, more preferably 10% by weight or more and 93% by weight or less.

Examples of the water-insoluble conductive particles include metals, metal oxides, metal fibers, carbon fibers, and carbon particles such as carbon black and graphite. Among these water-insoluble conductive particles, those having low reactivity with alkali metals, particularly lithium, are preferable, and metal powder and carbon particles are more preferable. The electric resistivity at 20 ° C. of the elements constituting the particles is preferably 5 × 10 ⁹ Ω · m or less.

As the metal powder, a metal having low reactivity with lithium, that is, a metal which is unlikely to form a lithium alloy is preferable, and specifically, copper, nickel, iron, chromium, molybdenum, titanium, tungsten, and tantalum are preferable. The shape of these metal powders may be any of a needle shape, a column shape, a plate shape, and a lump shape, and the maximum diameter is preferably 0.02 μm or more and 20 μm or less, more preferably 0.1 μm or more and 10 μm or less. It is preferable that the surface of these metal powders is not excessively oxidized. When the surfaces are oxidized, it is preferable to perform heat treatment in a reducing atmosphere.

As the carbon particles, there can be used known carbon materials which are conventionally used as a conductive material when the electrode active material is not conductive. Specifically, a conductive agent used when preparing an electrode mixture is used.

Examples of the water-insoluble particles having substantially no conductivity include fine powder of Teflon, SiC, aluminum nitride, alumina, zirconia, magnesia, mullite, forsterite, and steatite.
These particles may be used in combination with the conductive particles, and are preferably used in an amount of 0.01 to 10 times the conductive particles.

The positive (negative) electrode sheet can be prepared by applying a positive (negative) electrode mixture on a current collector, drying and compressing. For the preparation of the mixture, a positive electrode active material (or a negative electrode material) and a conductive agent are mixed, a binder (a suspension or emulsion of resin powder), and a dispersion medium are added and kneaded and mixed. The dispersion can be carried out by a stirring mixer such as a mixer, a homogenizer, a dissolver, a planetary mixer, a paint shaker, a sand mill, or a disperser. Water or an organic solvent is used as the dispersion medium, but water is preferred. In addition, additives such as a filler, an ion conductive agent, and a pressure enhancer may be appropriately added. The pH of the dispersion is 5 to 10 for the negative electrode and 7 to 10 for the positive electrode.
12 is preferred.

The coating can be performed by various methods.
Examples of the method include a reverse roll method, a direct roll method, a blade method, a knife method, an extrusion method, a slide method, a curtain method, a gravure method, a bar method, a dip method, and a squeeze method. A method using an extrusion die and a method using a slide coater are particularly preferable. The coating is preferably performed at a speed of 0.1 to 100 m / min. At this time, by selecting the above-mentioned coating method in accordance with the liquid physical properties and drying properties of the mixture paste, a good surface state of the coating layer can be obtained.
When the electrode layer has a plurality of layers, it is preferable to apply the plurality of layers simultaneously from the viewpoint of uniform electrode production, production cost, and the like. The thickness, length and width of the coating layer are determined by the size of the battery. A typical thickness of the coating layer is 10 to 1000 μm in a compressed state after drying. The electrode sheet after application is hot air, vacuum, infrared, far infrared,
It is dried and dehydrated by the action of electron beams and low humidity air. These methods can be used alone or in combination. The drying temperature is preferably in the range of 80 to 350C, particularly preferably in the range of 100 to 260C. The water content after drying is preferably 2000 ppm or less, more preferably 500 ppm or less. The compression of the electrode sheet can be performed by a commonly used pressing method, but a die pressing method and a calendar pressing method are particularly preferable. The press pressure is not particularly limited, but is preferably 10 kg / cm ^{2 to 3} t / cm ² . The press speed of the calendar press method is 0.1 ~
50 m / min is preferred. Press temperature is from room temperature to 200 ℃
Is preferred.

The separator that can be used in the present invention may be any thin film having high ion permeability, a predetermined mechanical strength, and an insulating thin film.
Fluorine polymer, cellulose polymer, polyimide, nylon, glass fiber, alumina fiber is used,
As the form, a nonwoven fabric, a woven fabric, or a microporous film is used. In particular, the material is preferably polypropylene, polyethylene, a mixture of polypropylene and polyethylene, a mixture of polypropylene and Teflon, a mixture of polyethylene and Teflon, and the form is preferably a microporous film. In particular, a microporous film having a pore size of 0.01 to 1 μm and a thickness of 5 to 50 μm is preferable. These microporous films may be a single film or a composite film composed of two or more layers having different properties such as the shape, density, and material of the micropores. For example, a composite film obtained by laminating a polyethylene film and a polypropylene film can be used.

The electrolyte generally comprises a supporting salt and a solvent. As a supporting salt in a lithium secondary battery, a lithium salt is mainly used. Examples of the lithium salt that can be used in the present invention include LiClO ₄ , LiBF ₄ , LiPF ₆ ,
_{LiCF 3 CO 2, LiAsF 6,} LiSbF 6, LiB 10
Cl ₁₀ , fluorosulfonic acid represented by LiOSO ₂ C _n F _{2n + 1} (n is a positive integer of 6 or less), LiN (SO ₂ C
_{n F 2n + 1) (SO} 2 C m F 2m + 1) represented by the imide salt (m, n is a positive integer, respectively 6 or less), LiC (SO
_{2 C p F 2p + 1)} (SO 2 C q F 2q + 1) (SO 2 C r F 2r + 1 methide salts (p represented by), q, r are each 6 or less positive integer), Lithium lower aliphatic carboxylate, LiAlCl
₄ , Li salts such as LiCl, LiBr, LiI, lithium chloroborane and lithium tetraphenylborate can be used, and one or more of these can be used in combination. Among them, those in which LiBF ₄ and / or LiPF ₆ are dissolved are preferable. The concentration of the supporting salt is not particularly limited, but may be 0.1 to 1 liter of the electrolytic solution.
2-3 moles are preferred.

Solvents usable in the present invention include propylene
Lencarbonate, ethylene carbonate, butyleneca
-Carbonate, chloroethylene carbonate, trifcarbonate
Fluoromethylethylene, difluoromethylethylene carbonate
, Monofluoromethyl ethylene carbonate, methyl hexafluoride
Acetate, methyl trifluoride acetate, dimethyl car
Bonate, diethyl carbonate, methyl ethyl carbonate
, Gamma-butyrolactone, methyl formate, methyl acetate
1,2-dimethoxyethane, tetrahydrofuran,
2-methyltetrahydrofuran, dimethylsulfoxy
Do, 1,3-dioxolan, 2,2-bis (trifluoro
Romethyl) -1,3-dioxolan, formamide, di
Methylformamide, dioxolan, dioxane, ace
Tonitrile, nitromethane, ethyl monoglyme, phosphorus
Acid triester, boric acid triester, trimethoxymeth
Tan, dioxolane derivative, sulfolane, 3-methyl-
2-oxazolidinone, 3-alkylsydnone (alk
Propyl, isopropyl, butyl, etc.), propyl
Lencarbonate derivative, tetrahydrofuran derivative,
Non-prototypes such as ethyl ether and 1,3-propane sultone
And rotonic organic solvents.
Or a mixture of two or more. Among these,
Carbonate solvents are preferred, and cyclic carbonates and
It is particularly preferable to use a mixture of acyclic carbonates.
No. Ethylene carbonate as a cyclic carbonate,
Propylene carbonate is preferred. Also, non-annular cars
As carbonates, diethyl carbonate, dimethyl carbonate
Carbonate and methyl ethyl carbonate are preferred.
As the electrolytic solution that can be used in the present invention, ethylene carbonate
Salt, propylene carbonate, 1,2-dimethoxyethyl
Tan, dimethyl carbonate or diethyl carbonate
LiCF is added to the electrolyte solution_ThreeSO_Three, LiCl
O_Four, LiBF_FourAnd / or LiPF₆Electrolyte containing
Is preferred. Especially propylene carbonate or ethyl
At least one of lencarbonate and dimethyl carbonate
And / or diethyl carbonate
LiCF in the mixed solvent_ThreeSO_Three, LiClO_FourOr
LiBF_FourLi and at least one salt selected from
PF ₆An electrolytic solution containing Put these electrolytes in the battery
The amount added to the material is not particularly limited.
It can be used depending on the amount and the size of the battery.

In addition to the electrolytic solution, the following solid electrolyte can be used in combination. Solid electrolytes are classified into inorganic solid electrolytes and organic solid electrolytes. Well-known inorganic solid electrolytes include nitrides, halides, and oxyacid salts of Li. Among them, Li ₃ N, LiI, Li ₅ N
_{I 2, Li 3 N-LiI} -LiOH, Li 4 SiO 4, Li
_{4 SiO 4 -LiI-LiOH, xLi} 3 PO 4 - (1-X) L
_{i 4 SiO 4, Li 2 SiS} 3, it is effective and phosphorus sulfide compounds.

As the organic solid electrolyte, a polyethylene oxide derivative or a polymer containing the derivative, a polypropylene oxide derivative or a polymer containing the derivative, a polymer containing an ion dissociating group, a mixture of a polymer containing an ion dissociating group and the above aprotic electrolyte solution , A phosphate matrix polymer, and a polymer matrix material containing an aprotic polar solvent are effective. Furthermore, there is a method of adding polyacrylonitrile to the electrolytic solution. In addition, a method of using an inorganic and an organic solid electrolyte in combination is also known.

Also, the purpose of improving discharge and charge / discharge characteristics
Then, another compound may be added to the electrolyte. For example,
Lysine, pyrroline, pyrrole, triphenylamine,
Phenyl carbazole, triethyl phosphite, tri
Ethanolamine, cyclic ether, ethylenediamine,
n-glyme, hexaphosphoric triamide, nitrobenze
Derivatives, sulfur, quinone imine dyes, N-substituted oxazones
Lizinone and N, N'-substituted imidaridinone, ethylene glycol
Recall dialkyl ether, quaternary ammonium salt,
Polyethylene glycol, pyrrole, 2-methoxy eta
Knoll, AlCl _Three, Conductive polymer electrode active material
Mer, triethylene phosphoramide, trialkyl phos
Aryl compounds having fin, morpholine and carbonyl groups
, Crown ethers such as 12-crown-4,
Hexamethylphosphoric triamide and 4-alkylmo
Ruphorin, bicyclic tertiary amine, oil, quaternary phosphoni
And tertiary sulfonium salts.
You. Particularly preferred are triphenylamine, phenylca
When using rubazole alone or in combination
You.

Further, in order to make the electrolytic solution nonflammable, a halogen-containing solvent such as carbon tetrachloride and ethylene trifluoride chloride can be contained in the electrolytic solution. In addition, carbon dioxide gas can be included in the electrolytic solution in order to provide suitability for high-temperature storage.

It is desirable that the electrolyte contains as little water and free acid as possible. For this reason, it is preferable that the raw material of the electrolytic solution is sufficiently dehydrated and purified. The adjustment of the electrolytic solution is preferably performed in dry air or an inert gas having a dew point of −30 ° C. or less. The amount of water and free acid in the electrolytic solution is 0.1 to 500 ppm, more preferably 0.2 to 100 ppm.

The total amount of the electrolytic solution may be injected at one time, but it is preferable to inject it in two or more portions. In the case of injecting two or more times, each liquid may have the same composition but different compositions (for example, after injecting a non-aqueous solvent or a solution in which a lithium salt is dissolved in a non-aqueous solvent, a non-aqueous solution having a higher viscosity than the solvent may be used). A solution in which a lithium salt is dissolved in a solvent or a non-aqueous solvent is injected). Further, in order to shorten the injection time of the electrolyte solution, the pressure of the battery can may be reduced, or a centrifugal force or an ultrasonic wave may be applied to the battery can.

The battery can and the battery lid which can be used in the present invention are made of nickel-plated iron steel plate or stainless steel plate (SUS304, SUS304L, SUS304).
N, SUS316, SUS316L, SUS430, S
US444, etc.), nickel-plated stainless steel plate (same as above), aluminum or its alloy, nickel,
They are titanium and copper, and have a shape of a perfect circular cylinder, an elliptical cylinder, a square cylinder, or a rectangular cylinder. In particular, when the outer can also serves as the negative electrode terminal, a stainless steel plate or a nickel-plated iron steel plate is preferable, and when the outer can also serves as the positive electrode terminal, a stainless steel plate, aluminum or an alloy thereof is preferable. The shape of the battery can may be any of buttons, coins, sheets, cylinders, corners, and the like. A safety valve can be used for the sealing plate as a measure against the rise in the internal pressure of the battery can. In addition, a method of cutting a member such as a battery can or a gasket can also be used. In addition, various conventionally known safety elements (for example, a fuse, a bimetal, a PTC element, or the like as an overcurrent prevention element) may be provided.

For the lead plate used in the present invention, a metal having electrical conductivity (for example, iron, nickel, titanium, chromium, molybdenum, copper, aluminum, etc.) or an alloy thereof can be used. Battery lid, battery can, electrode sheet,
As a method for welding the lead plate, a known method (eg, DC or AC electric welding, laser welding, ultrasonic welding) can be used. A conventionally known compound or mixture such as asphalt can be used as the sealing agent for sealing.

The gaskets usable in the present invention are olefin polymers, fluorine polymers, cellulose polymers, polyimides and polyamides, and olefin polymers are preferred from the viewpoint of organic solvent resistance and low moisture permeability. Propylene-based polymers are preferred. Further, it is preferably a block copolymer of propylene and ethylene.

The battery assembled as described above is
It is preferable to perform an aging treatment. The aging treatment includes a pretreatment, an activation treatment, and a post-treatment, whereby a battery having high charge / discharge capacity and excellent cycleability can be manufactured. The pre-treatment is a treatment for making the distribution of lithium in the electrode uniform, such as a control of dissolution of lithium, a temperature control for making the distribution of lithium uniform, a swing and / or rotation treatment, and an optional charge and discharge. Are performed. The activation process is a process for inserting lithium into the negative electrode of the battery body, and it is preferable to insert 50 to 120% of the amount of lithium inserted when the battery is actually used and charged.
The post-processing is a process for sufficiently activating the activation process,
There are a preservation process for making the battery reaction uniform and a charge / discharge process for determination, and these can be arbitrarily combined.

Preferred aging conditions (pretreatment conditions) before activation of the present invention are as follows. The temperature is preferably from 30 ° C. to 70 ° C., more preferably from 30 ° C. to 60 ° C., and even more preferably from 40 ° C. to 60 ° C. The open circuit voltage is preferably 2.5 V or more and 3.8 V or less,
2.5 V or more and 3.5 V or less are more preferable, and 2.8 V or more and 3.3 V or less are more preferable. Aging period is 1
It is preferably from 20 days to 20 days, particularly preferably from 1 day to 15 days. The charging voltage for activation is preferably 4.0 V or more, more preferably 4.05 V or more and 4.3 V or less, and 4.0 V or more.
The voltage is more preferably from 1 V to 4.2 V. As the aging condition after activation, the open circuit voltage is 3.9 V or more and 4.3 V.
The temperature is preferably from 4.0 V to 4.2 V, and the temperature is preferably from 30 ° C. to 70 ° C.
A temperature of at least 60 ° C is particularly preferred. The aging period is 0.
It is preferably from 2 days to 20 days, particularly preferably from 0.5 days to 5 days.

The battery of the present invention is covered with an exterior material if necessary. Examples of the exterior material include a heat-shrinkable tube, an adhesive tape, a metal film, paper, cloth, paint, a plastic case, and the like. Further, at least a part of the exterior may be provided with a portion that changes color by heat so that the heat history during use can be recognized.

The batteries of the present invention are assembled in series and / or in parallel as required and stored in a battery pack. In addition to safety elements such as positive temperature coefficient resistors, thermal fuses, fuses and / or current interrupting elements, battery packs have safety circuits (voltage, temperature, current, etc. of each battery and / or assembled battery as a whole, Then, a circuit having a function of interrupting the current may be provided. In addition to the positive and negative terminals of the whole battery pack, the positive and negative terminals of each battery, the temperature detection terminals of the whole battery pack and each battery, the current detection terminals of the whole battery pack, etc. shall be provided as external terminals on the battery pack. Can also. The battery pack may have a built-in voltage conversion circuit (such as a DC-DC converter). In addition, connection of each battery
The lead plate may be fixed by welding, or may be fixed with a socket or the like so as to be easily detachable. Further, the battery pack may be provided with a display function of the remaining battery capacity, the presence or absence of charging, the number of times of use, and the like.

The battery of the present invention is used for various devices.
In particular, video movies, portable VCRs with built-in monitors, movie cameras with built-in monitors, digital cameras, compact cameras, SLR cameras, film with lenses, notebook computers, notebook word processors, electronic organizers,
It is preferably used for mobile phones, cordless phones, razors, electric tools, electric mixers, automobiles and the like.

[0060]

EXAMPLES The present invention will be described in more detail with reference to specific examples below, but the present invention is not limited to the examples.

Example-1 Polycrystalline silicon simple substance (compound-1) as a negative electrode material, and a Si-Ag alloy (compound-2 atomic ratio 60-40, compound-3 atomic Ratio 80-20, compound-4 atomic ratio 30-70), Si
-Al (compound-5 atomic ratio 60-40), Si-Ag
—Cd (compound-6 60-30-10), Si—Zn
(Compound-7 atomic ratio 60-40), Si-Au (compound -68 atomic ratio 60-40), Si-Ag-In (compound-9 atomic ratio 60-30-10), Si-Ge (compound-10 Atomic ratio 60-40), Si-Ag-Sn (compound-11 atomic ratio 60-30-10), Si-Ag-
Sb (compound-12 atomic ratio 60-30-10), Si
-Ag-Ni (compound-13 atomic ratio 60-30-1
0), silicon obtained by pulverizing silicon in which 100% of Li was eluted from metallurgically synthesized Li ₄ Si using isopropyl alcohol in argon gas (compound-1)
4) Compound -1 of silicon and colloidal silica were mixed, Si-SiO ₂ which was powder solid obtained by heating at 1000 ° C. with a vibration mill in an argon gas (Compound -15 weight ratio 80 -20, compound-16 weight ratio 90
-10, compound-17, weight ratio 60-400), Si-Al ₂ O ₃ obtained by using alumina sol in the same manner.
(Compound -18 weight ratio 90-10), Compound-2 to the compound was deposited SiO ₂ in the same manner as the compound -16 (Compound -19 Compound-2-SiO ₂ weight ratio of 90
-10), Ag-plated (dextrin as a reducing agent, AgNO ₃ as an Ag source) as a compound plated on the silicon surface of compound-1 by an electroless plating method, and an atomic ratio of silicon (compound-20Si-Ag) of 60 -40),
Also plated with Ni (NaH ₂ PO ₂ as a reducing agent,
Ni source (NiSO ₄ ) silicon (compound-21Si)
-Ni atomic ratio 60-40, Compound-22 atomic ratio 8
0-20, Compound -23 atomic ratio 30-70), NaBH _4, ZnO as Zn source) silicon (atomic ratio of the compound -24Si-Zn as similarly to Zn plating (reducing agent
60-40), a compound obtained by plating compound-2 with Ni by an electroless plating method (compound-25 compound-2-Ni)
Weight ratio 80-20) 30 g of silicon of compound-1 was added to a solution of 3 g of polyvinylidene fluoride in 50 g of N-methylpyrrolidone, mixed and kneaded, dried, and pulverized in an automatic mortar (compound- 26) was used. A compound obtained by coating compound-2 with polyvinylidene fluoride by the above method (weight ratio of compound-27 compound-2-vinylidene fluoride 90-10), and a compound obtained by coating compound-14 with Ag by electroless plating ( Compound-28 Si
-Ag atomic ratio 60-40), and a compound coated with Ni (Compound-29 Si-Ni atomic ratio 60-).
40), a compound obtained by coating compound-14 with polyvinylidene fluoride in the same manner as compound-30 (compound-30Si
-Polyvinylidene fluoride weight ratio 90-10), a compound obtained by coating compound 30 with Ni by an electroless plating method (compound-31 compound-30-Ni weight ratio 70-3)
0), a compound obtained by coating Compound-15 with Ag by electroless plating (weight ratio of Compound-32 Compound-15-Ag 70-30), and a compound coated with Ni (Compound-33 Compound-15-Ni) Weight ratio of 70-3
0), a compound coated with polyvinylidene fluoride using compound-15 (weight ratio of compound-34 compound-15-polyvinylidene fluoride 90-10) was used. Compound obtained by coating compound-34 with Ag by electroless plating (compound-35 compound-34-Ag weight ratio 80-2)
0), similarly Ni-plated compound (compound-36 compound-34-Ni weight ratio 80-20) The average particle size of the above negative electrode materials (compounds 1-36) is in the range of 0.05-4 μm. Was. Next, 190 g of a powder obtained by sufficiently mixing the above negative electrode material (compounds 1 to 36) and an equal weight of flaky natural graphite, and 10 g of polyvinylidene fluoride as a binder were added to N-methyl-2-pyrrolidone. The resultant was dispersed in 500 ml to prepare a negative electrode paste.

[0062] 200 g of the positive electrode active material LiCoO ₂ and 10 g of acetylene black were mixed with a homogenizer, and then 5 g of polyvinylidene fluoride as a binder were mixed.
-Methyl-2-pyrrolidone (500 ml) was added and kneaded and mixed to prepare a positive electrode mixture paste.

The positive electrode mixture paste prepared above was coated on both sides of a 30 μm thick aluminum foil current collector with a blade coater, dried at 150 ° C., compression-molded with a roller press, cut into a predetermined size, and stripped. A positive electrode sheet was prepared. Further, it was sufficiently dehydrated and dried with a far-infrared heater in a dry box (dew point; dry air having a temperature of -50 ° C. or lower) to prepare a positive electrode sheet. Similarly, paste the negative electrode mixture
m of the copper foil current collector, and a negative electrode sheet was prepared in the same manner as in the preparation of the positive electrode sheet. The amount of application of the positive and negative electrodes was adjusted so that the charge capacity in the first cycle when the positive electrode active material was 4.2 V with respect to lithium metal and the charge capacity in the first cycle when the negative electrode material was 0.0 V were matched. The amount of the mixture applied was adjusted.

Next, an electrolyte was prepared as follows. In an argon atmosphere, 65.3 g of diethyl carbonate was placed in a 200 cc narrow-neck polypropylene container, and the liquid temperature was 3
22.2 g of ethylene carbonate were dissolved in small portions, taking care not to exceed 0 ° C. Next, 0.4 g of LiB
F _4, taking care of LiPF ₆ 12.1g so as not to exceed the liquid temperature is 30 ° C., each in turn, and dissolved little by little in the polypropylene container. The obtained electrolyte was a colorless and transparent liquid having a specific gravity of 1.135. 18 pp water
m (measured with a Karl Fischer moisture meter, product name: MKC-210, manufactured by Kyoto Electronics Co., Ltd.), and the free acid content is 24 ppm (using bromthymol blue as an indicator, 0.1 N NaOH
Neutralization titration using an aqueous solution and measured).

The cylinder battery was prepared as follows. A method of manufacturing a battery will be described with reference to FIG. The positive electrode sheet, the microporous polyethylene film separator, the negative electrode sheet, and the separator prepared above were sequentially laminated, and the resultant was spirally wound. The wound electrode group (2) was housed in a nickel-plated iron bottomed cylindrical battery can (1) also serving as a negative electrode terminal, and an upper insulating plate (3) was further inserted. After injecting the electrolytic solution into the battery can, a positive electrode terminal (6), an insulating ring, a PTC element (63), a current interrupter (62), and a pressure-sensitive valve (61) are laminated on a gasket (5). ) To form a cylindrical battery.

The above cylindrical battery is charged at 1.5 A.
In this case, charging was performed at a constant current up to 4.2 V, and the charging current was controlled so as to keep the voltage constant at 4.2 V until 2.5 hours had elapsed from the start of charging. Discharging was performed at a constant current up to 3.0 V with a 0.2 C current. Table 1 shows the discharge capacity, average discharge voltage, energy amount (discharge capacity × average discharge voltage) in the first cycle, and the capacity retention ratio in the 30th cycle of repeated charging and discharging.

Table 1 Battery Negative electrode material Discharge capacity Average discharge energy amount Cycle life No. Compound-(mAh) Voltage (V) (Wh) (30 cycle%) 1 1 2300 3.5 8.0 70 70 2 2 2000 3.5 7.0 82 3 3 2100 3.5 7.5 803 4 4 1800 3.5 6.3 83 5 5 2000 3.5 7.0 7.0 79 966 2000 3.5 7.0 84 77 7 2000 3.5 7.0 83 8 8 1900 3.5 6.5 6.6 81 9 9 2000 3.5 7.0 82 10 10 2000 3.5 7.0 7.0 83 11 11 2200 3.5 7.6 81 12 12 2000 3.5 7.0 81 13 13 2000 3.5 7.0 7.0 81 14 14 2300 3.5 8.0 78 15 15 2200 3.5 7.6 85 16 16 2200 3.5 7.6 84 17 17 2100 3.5 7.3 83 18 18 2000 3.5 3.5 7.0 75 19 19 2000 3.5 7.0 7.0 86 20 20 2100 3.5 7.5 80 21 21 2100 3.5 7.3 84 22 22 2200 3.5 7.6 81 23 23 1800 3.5 6.3 86 24 24 2000 3.5 7.0 81 25 25 2000 3.5 7.0 85 26 26 2200 3.5 7.6 82 27 27 2100 3.5 7.3 83 28 28 2000 3.5 7.0 83 29 29 2000 3.5 7.0 85 85 30 30 2200 3.5 7.3 84 31 31 2000 3.5 7.0 86 32 32 2000 3.5 7.0 87 33 33 2200 3.5 7.6 85 34 34 2000 3.5 7.0 7.0 86 35 35 2000 3. 7.0 87 36 36 2000 3.5 7.0 89

Example 2 Compounds 1, 2, 14, 15, 19, 21 of Example 1
Regarding 26, 29, 32, 34, and 36, in Example 1, the first cycle charge capacity in which the positive electrode active material was 4.2 V with respect to lithium metal and the first charge capacity in which the negative electrode material was 0.1 V were used. The application amount of each electrode mixture was adjusted so that the charge capacity of the cycle was matched. The charge / discharge test was performed under the same conditions as in Example 1 except that the voltage at the end of charging was 4.1 V. The amount of lithium inserted into silicon was about 3.2 mol. (When represented by Li _x Si, it means x = 3.2.)

Table 2 Battery Negative electrode material Discharge capacity Average discharge energy amount Cycle life number (mAh) Voltage (V) (Wh) (30 cycle%) 371 1700 3.6 6.1 78 38 2 1600 3.6 5. 7 85 39 14 1600 3.6 5.7 83 40 15 1600 3.6 5.7 90 90 41 19 1600 3.6 5.7 89 42 21 1700 3.6 6.1 86 43 43 26 1600 3.6 5. 7 87 44 29 1600 3.6 5.7 89 45 32 1600 3.6 5.7 91 91 46 34 1600 3.6 5.7 90 47 36 1600 3.6 5.7 92

Example 3 Compounds 1, 2, 14, 15, 19, 21 of Example 1
26, 29, 32, 34, and 36, the weight ratio of the conductive agent to graphite in Example 1 was 80 (negative electrode material) and 2
The test was performed under the same conditions except that the value was 0 (graphite).

Table 3 Battery Negative electrode material Discharge capacity Average discharge energy amount Cycle life number (mAh) Voltage (V) (Wh) (30 cycle%) 48 1 2300 3.5 8.0 65 49 2 2200 3.5 7.5. 6 81 50 14 2300 3.5 8.0 73 51 51 15 2300 3.5 8.0 80 52 19 2200 3.5 7.6 85 53 53 21 2200 3.5 7.6 83 54 54 26 2300 3.5 8.5. 0 78 55 29 2100 3.5 7.3 84 56 32 2100 3.5 7.3 86 57 34 2100 3.5 7.3 85 58 36 36 2100 3.5 7.3 88

Example 4 Compounds 1, 2, 14, 15, 19, 21 of Example 1
26, 29, 32, 34, and 36 were tested in an aqueous system instead of the N-methylpyrrolidone system of Example-1.
Specifically, the negative electrode sheet is composed of 95% by weight of the negative electrode material and flake graphite, 4% by weight of an aqueous dispersion of polyvinylidene fluoride as a binder, and 1% by weight of carboxymethyl cellulose.
Water is added to the mixture consisting of
The mixture was kneaded at 0 rotation for 10 minutes or more to prepare a negative electrode mixture slurry. The obtained slurry was applied to both sides of a copper film having a thickness of 18 μm to prepare a negative electrode sheet. As a positive electrode mixture, 90% by weight of a positive electrode active material LiCoO ₂ , 6% by weight of acetylene black, and a mixture of 3% by weight of an aqueous dispersion of polyvinylidene fluoride and 1% by weight of sodium polyacrylate as a binder were mixed with water. In addition, the mixture was kneaded, and the obtained slurry was applied to both sides of an aluminum film having a thickness of 30 μm to prepare a positive electrode sheet. Next, a protective layer (average thickness 5 μm) made of a 1: 4 (weight ratio) mixture of flaky graphite and aluminum oxide (average particle size 2 μm) was applied on the surface of the active material layer of the negative electrode sheet. The charge / discharge test was performed under the same conditions as in Example-1.

Table 4 Battery Negative electrode material Discharge capacity Average discharge energy amount Cycle life number (mAh) Voltage (V) (Wh) (30 cycle%) 59 1 2300 3.5 8.0 71 60 2 2000 3.5 7.5. 0 82 61 14 2300 3.5 8.0 79 79 62 15 2200 3.5 7.6 87 63 63 19 2000 3.5 7.0 86 64 21 21 100 3.5 7.3 85 65 26 2200 3.5 7.5. 6 82 66 29 2000 3.5 7.0 85 85 67 32 2000 3.5 7.0 87 68 34 2000 3.5 7.0 87 69 36 2000 3.5 7.0 90 90

Comparative Example 1 The same test as in Examples 1 and 2 was conducted except that polycrystalline silicon of 70 μm was used. Comparative Example 2 The same test was performed as in Example 1 and Example 2 except that 2 μm of polycrystalline silicon was used, and the addition weight ratio of the silicon and the flaky graphite in the negative electrode mixture was 96 to 4%. Comparative Example-3 A battery was prepared in the same manner as in Example 1 except that mesophase pitch coke was used as a negative electrode material and acetylene black was added as a conductive auxiliary agent at 2% by weight, and a charge / discharge test was performed.

Table 5 Battery Discharge Capacity Average Discharge Energy Amount Cycle Life Number (mAh) Voltage (V) (Wh) (30 Cycle%) Comparative Example-1-1 2000 3.5 7.0 60 Comparative Example-1-2 1800 3.6 6.4 65 Comparative Example-2-1 2400 3.4 8.2 40 Comparative Example-2-2 2200 3.6 7.9 45 Comparative Example-3 1400 3.7 5.0 92

Comparing the battery performance of the battery of Example 1 using the compound of the present invention with that of Comparative Example 1, the compound of the present invention having a small average particle size is excellent in cycle life.
Further, in comparison with Example-1, the alloy, silicon from which lithium was removed from lithium silicide, silicon to which colloidal silica was adhered, silicon coated with metal by plating, silicon coated with polyvinylidene fluoride,
These combined compounds have improved cycle life over untreated silicon. Further, by combining the treatments of the present invention, the cycle life is improved as compared with the single treatment. In the test of Example-2,
By reducing the amount of lithium inserted into silicon, the discharge capacity is reduced, but the average discharge voltage is increased and the cycle life is improved. From Example-3, the silicon compound coexisting with the metal had a larger discharge capacity and a cycle life almost equal to that of Example-1. In Example-4, N
-Compared to a non-aqueous solvent coating system such as methylpyrrolidone, the water coating system also provided almost the same performance. From Comparative Example-3, the discharge capacity is higher and the energy amount is higher than the carbonaceous material.
The above results indicate that the positive electrode active material LiCoO ₂ was replaced with LiNiO ₂
The same effect was obtained by changing to LiMn ₂ O ₄ . Further, compounds containing the additive E described on page 20 in these positive electrode active materials also obtained similar results.

[0077]

According to the present invention, it is possible to obtain a non-aqueous secondary battery having improved energy amount and cycle life.

[Brief description of the drawings]

FIG. 1 is a sectional view of a cylinder battery used in Examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery can also serve as a negative electrode 2 Wound electrode group 3 Upper insulating plate 4 Positive electrode lead 5 Gasket 6 Battery lid also serving as a positive electrode terminal 61 Pressure sensitive valve element 62 Current cutoff element (switch) 63 PTC element

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobufumi Mori 210 Nakanakanuma, Minamiashigara-shi, Kanagawa Prefecture Fuji Photo Film Co., Ltd. (72) Inventor Kokatsu Kagawa 210 Nakanakanuma Minamiashigara-shi, Kanagawa Fuji Photo Film Co., Ltd. 72) Inventor Akira Kase 210 Nakanuma, Minamiashigara-shi, Kanagawa Prefecture, Fuji Photo Film Co., Ltd. (72) Inventor Hajime Miyamoto 210 Nakanuma, Minamiashigara-shi, Kanagawa Prefecture, Fuji Photo Film Co., Ltd. BB05 BB32 BC01 BC05 BC06 BD02 5H014 AA02 EE02 EE05 EE08 EE10 HH00 HH01 5H029 AJ03 AJ05 AK02 AK03 AL01 AL02 AL04 AL06 AL11 AL12 AM01 AM02 AM03 AM04 AM05 AM07 AM11 AM12 AM16 BJ02 BJ12 HJ12 DJ14

Claims (10)

[Claims] In a non-aqueous secondary battery comprising a positive electrode having a positive electrode active material, a negative electrode having a negative electrode material, and a non-aqueous electrolyte, the positive electrode active material is capable of inserting and releasing lithium. Wherein the negative electrode material is a compound containing a silicon atom capable of inserting and releasing lithium. 2. The silicon compound has an average particle size of 0.1.
The non-aqueous secondary battery according to claim 1, wherein the thickness of the non-aqueous secondary battery is from 01 to 50 m. 3. The non-aqueous secondary battery according to claim 1, wherein the silicon compound is an alloy. 4. The silicon compound according to claim 1, wherein said silicon compound is silicon obtained by removing a metal from a metal silicide.
The non-aqueous secondary battery according to any one of the above. 5. The method according to claim 1, wherein said silicon compound is attached to a ceramic which does not react with lithium.
5. The non-aqueous secondary battery according to any one of 4. 6. The non-aqueous secondary battery according to claim 1, wherein the silicon compound is coated with at least a metal. 7. The non-aqueous secondary battery according to claim 1, wherein said silicon compound is previously coated with a thermoplastic resin. 8. A method according to claim 1, wherein carbon is added in a weight ratio of 5 to said silicon compound.
The non-aqueous secondary battery according to any one of claims 1 to 7, wherein the non-aqueous secondary battery is present in an amount of 1 to 1900%. 9. The charge / discharge range of the silicon compound is such that x is in the range of 0 to 4.2 as represented by Li _x Si as an equivalent ratio of lithium inserted into and released from silicon. Item 9. The non-aqueous secondary battery according to any one of Items 1 to 8. 10. The positive electrode active material is Li_yMO_Two(M = C
o, at least one of Ni, Fe and Mn, y = 0 to 1.
The compound represented by 2), or Li_zN_TwoO _Four(N = M
Compound having a spinel structure represented by nz = 0 to 2)
Claims: At least one of the following:
10. The non-aqueous secondary battery according to any one of 1 to 9.