JP3262404B2 - Non-aqueous electrolyte battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte battery,
In particular, the present invention relates to a non-aqueous electrolyte battery having improved charge / discharge cycle characteristics using an electrode in which the electrode active material is prevented from falling off by a binder.

[0002]

2. Description of the Related Art In aqueous electrolytes such as manganese dry batteries, alkaline dry batteries and nickel-cadmium secondary batteries, starch, polyvinyl alcohol, carboxymethyl cellulose (Japanese Unexamined Patent Publication Nos. 1-175171 and 1-105471) are used as binders for electrode active materials. JP-A-51-5538 and 50-2
6500), hydroxypropylcellulose (JP-A-63-245859 and JP-A-54-49541), regenerated cellulose (JP-A-61-91872), polyvinyl chloride, polyvinylpyrrolidone, and the like. As the electrolyte, Teflon or the like is generally used. (“Battery Handbook” published by Denki Shoin, 1980) In particular, in secondary batteries, the positive electrode or negative electrode repeatedly expands or contracts in volume during charging and discharging.
The active material particles and the conductive agent fall off, which causes the charge / discharge cycle life to be shortened. As a means for preventing this, it is important to select a binder. However, the above-mentioned binder was insufficient to prevent the falling off of the active material and the like. On the other hand, Japanese Patent Application Laid-Open No. 3-108263 discloses a binder for a positive electrode that prevents the active material from falling off, and describes that the charge / discharge cycle life has been improved. Poor affinity for aqueous electrolyte, low utilization of active material, and insufficient charge / discharge cycle life. Further, there is a drawback that the internal resistance is significantly increased when the amount of addition is increased. In addition, US Pat.
No.-255670 discloses that a rubber-based polymer (elastomer) is used as a binder for a negative electrode of a secondary battery. However, all of these binders have an adhesive force with a current collector such as a metal foil. There is a disadvantage that the active material is poor and easily peels off and falls off.

As described above, the charge / discharge cycle life and the utilization rate of the active material (that is, discharge capacity) are inconsistent performances, and a binder technology that balances them has been desired. Also, in the primary battery, the lithium battery adopts a spiral structure in which sheet electrodes are wound to reduce the internal resistance, and the shape of the current collector is changed to a sheet shape so as to cope with heavy load discharge. Some are made of metal foil. However,
If the adhesion of the coating of the active material applied on the current collector is weak, the active material may peel off or fall off during the assembly of the battery such as a coil, resulting in many defective products. As a factor for improving the adhesive strength between the active material and the current collector, there is a binder. JP-A-3-222258 discloses a binder for improving the adhesive strength, but its performance is still insufficient.

[0004]

An object of the present invention is to provide a non-aqueous
An object of the present invention is to prevent an electrode active material from falling off in an electrolyte battery and achieve good charge / discharge characteristics.

[0005]

The object of the present invention is to provide a positive electrode active material, a negative electrode active material and an electrolyte having ion conductivity.
In a non-aqueous electrolyte battery, this was achieved by including a polymer represented by the following general formula (I) as a binder in a positive electrode mixture and / or a negative electrode mixture. General formula (I)

[0006]

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However, in the formula, R¹Is a hydrogen atom or 1 carbon atom
Alkyl groups of 2 to 2, R^TwoIs alkyl having 1 to 12 carbons
Group, aryl group having 6 to 12 carbon atoms or 7 to 13 carbon atoms
An aralkyl group of R^ThreeIs a hydrogen atom or a group having 1 to 2 carbon atoms
R represents an alkyl group;^Four, R ^FiveIs a hydrogen atom or carbon
An alkyl group having 1 to 12 carbon atoms and an aryl group having 6 to 12 carbon atoms
Or an aralkyl group having 7 to 13 carbon atoms, and x is 5
40 to 90% by weight, y is 40 to 90% by weight, z is 1 to 20 weights
%. Where x + y + z = 100% by weight.
You.

In the general formula (I), the preferred copolymerization ratio is x = 5-35, y = 50-80, z = 2-15% by weight, more preferably x = 5-30, y = 60-8.
0, z = 2 to 10% by weight. Preferred examples of R ¹ are hydrogen or a methyl group, and preferred examples of R ² are a methyl group, an ethyl group, an n-butyl group, an n-hexyl group, an n-dodecyl group, an iso-butyl group, a phenyl group,
Preferred examples of R ³ include a hydrogen atom, a methyl group, and an ethyl group. Preferred examples of R ⁴ and R ⁵ include a hydrogen or a methyl group, an ethyl group, and an n-butyl group. Group, n-hexyl group, n-dodecyl group, iso-butyl group, phenyl group, naphthyl group, benzyl group and the like. Further, R ⁴ and R ⁵ may be the same or different. Preferred specific examples of the polymer according to the invention are shown below, but the invention is not limited thereto.

[0009]

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[0010]

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[0011]

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[0012]

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The preferable addition amount of the polymer of the present invention is 0.5 to 20% by weight, more preferably 1 to 10% by weight, based on the whole mixture.

When the unreacted functional group of the polymer or compound of the present invention hinders the subsequent battery reaction, it can be removed by an appropriate treatment (heating, washing with a solvent, etc.). The active material that can be used in the present invention may be any electrode material. In particular, for a lithium secondary battery, among the inorganic compound positive electrode active materials, Co oxides (Japanese Patent Application Laid-Open Nos. 52-12,424 and DE 2,606) are used. , 915),
Li-Co oxide (JP-A-55-136131, US
3,945,848, US4,340,652),
Li-Ni-Co oxides (EP243,926A, JP-A-63-114,063, JP-A-63-211,565, JP-A-63-299,056, JP-A-1-120,765, etc.), V oxides (FR21 , 611,796, JP-A-5
5-53,077, 62-140,362, 62-
227, 358, etc.), Li-V oxide (electrochemical 48)
432 (1980), Journal of Electrochemical Society, 130 1225 (19
83), JP-A-2-12,769), Mn oxide (EP 269,855, JP-A-63-58,761, etc.), Li-Mn oxide (JP-A-56,136,46)
4, 114,064, 114,065, 148,
550, 221 and 559, JP-A-5-559, 1-109,662, 1-128,371, 1-2
09,663, 2-27,660), Li-Ni-M
and n-oxides (JP-A-63-210, 028, etc.).

[0015] In addition, of the organic polymer positive electrode active material, a polyaniline derivative (Molecular, crystal and liquid crystal 121, pp. 173 (1985), JP-A-60-197,728, the same 63-46,223, 63 243, 131, JP-A-2-219,823, etc.), pyrrole derivatives (Journal of Chemical Society Chemical Communication 854 (1)
979), DE 3,223,544A3A, 307,
954A, JP-A-62-225517, and 63-6
9,824, JP-A-1-170,615, etc., polythiophene derivatives (JP-A-58,187,432, JP-B-1-12,775, etc.), and polyacene derivatives (JP-A-5,197,197).
8-209, 864) and polyparaphenylene derivatives. Each derivative includes a copolymer.

This organic polymer compound is described in detail in "Conductive Polymers", edited by Naoya Ogata, published by Kodansha Scientific (1990). As a secondary battery negative electrode active material that can contain the compound of the present invention,
In lithium secondary batteries, fired carbonaceous compounds capable of occluding lithium ions or lithium metal in addition to metallic lithium and its alloys (JP-A-58-209,864 and JP-A-61-2)
14,417, 62-88,268, 62-21
6,170, 63-13,282, 63-24,5
55, 63-121, 247, 63-121, 25
7, 63-155,568, 63-276,87
3, ibid. 63-314,821, JP-A-1-204,36
1, 1-221, 859, 1-274, 360, etc.).

When the compound of the present invention is added to the calcined carbonaceous compound, for example, by adding a compound which reacts with a hydroxyl group such as an isocyanate group, a group which reacts with lithium contained in the compound of the present invention is lost. It is preferable to activate.

[0018] By absorbing and releasing lithium ions,
Other negative electrode active materials include TiS_Two, LiTiS_Two
(U.S. Pat. No. 3,983,476), WO_Two(US Patent
No. 4,198,476), LixFe (Fe_Two) O_FourWhat
Which spinel compound (JP-A-58-220362), F
e_TwoO_ThreeLithium compound (JP-A-3-11207)
0), Nb_TwoO_Five(Japanese Patent Publication No. 62-59412;
-82447), iron oxide, FeO, Fe_TwoO_Three, Fe_Three
O_Four, Cobalt oxide, CoO, Co_TwoO_Three, Co_ThreeO_Four
(JP-A-3-291,862) is known. Also,
Li_pM_qV_1-qO _r(Where M is a transition metal, p = 0.
2 to 2.5, q = 0 to 1, r = 1.3 to 4)
Of Li-containing composite metal oxide as negative electrode active material
Can be.

[0019]

The electrode mixture can usually contain a conductive material such as carbon, silver (JP-A-63-148,554) or polyphenylene derivative (JP-A-59-20,971). As the negative electrode active material of the lithium secondary battery used together with the positive electrode mixture of the present invention, in the case of a lithium secondary battery, lithium metal, lithium alloy (A
1, Al-Mn (U.S. Pat. No. 4,820,599), Al
-Mg (JP-A-57-98977), Al-Sn (JP-A-63-6,742), Al-In, Al-Cd (JP-A-1-144,573) and the like.

As the electrolyte, propylene carbonate, ethylene carbonate, diethylene carbonate,
γ-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolan, formamide, dimethylformamide, dioxolan, acetonitrile, nitromethane, phosphate triester (JP-A-6
0-23,973), trimethoxymethane (JP-A-61
-4,170), a dioxolane derivative (JP-A-62-1)
5,771, 62-22,372, 62-108,
474), sulfolane (JP-A-62-31959),
3-Methyl-2-oxazolidinone (JP-A-62-4)
4,961), propylene carbonate derivatives (JP-A-62-290,069 and JP-A-62-290,071), and tetrahydrofuran derivatives (JP-A-63-3287).
2), ethyl ether (JP-A-63-62166),
1,3-propane sultone (JP-A-63-10217)
3) a solvent in which at least one or more aprotic organic solvents are mixed and a lithium salt soluble in the solvent, for example, ClO ₄ ⁻ , BF ₆ ⁻ , PF ₆ ⁻ , CF ₃ S
O ₃ ⁻ , CF ₃ CO ₂ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , B
₁₀ C ₁₀ (JP-57-74,974), (1,2-dimethoxyethane) 2ClO ₄ ^- (JP 57-74,97
7), lower aliphatic carboxylate (JP-A-60-41,7
73), AlCl ₄ ⁻ , Cl ⁻ , Br ⁻ , I ⁻ (JP-A-60-247,265), chloroborane compounds (JP-A-61-165957), tetraphenylboric acid (JP-A-6-1987)
1-214, 376). In particular, LiClO ₄ or LiBF is added to a mixed solution of propylene carbonate and 1,2-dimethoxyethane.
_An electrolyte containing ₆ is typical.

In addition to the electrolytic solution, the following solid electrolyte can be used. 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, LiSiO 4, L
iSiO ₄ -LiI-LiOH (JP-A-49-811.8)
_{99), xLi 3 PO 4 -} (1-x) Li 4 SiO
₄ (JP-A-59-60,866), Li ₂ SiS ₃ (JP-A-60-501,731), phosphorus sulfide compound (JP-A-62-82,665) and the like are effective.

As the organic solid electrolyte, a polyethylene oxide derivative or a polymer containing the derivative (JP-A-63-1)
35,447), a polypropylene oxide derivative or a polymer containing the derivative, and a polymer containing an ion dissociating group (Japanese Patent Application Laid-Open Nos. 62-254,302 and 62-254,30).
3, 63-193, 954), a mixture of a polymer containing an ion-dissociating group and the aprotic electrolyte (U.S. Pat. Nos. 4,792,504 and 4,830,939;
2-22,375, 62-22,376, 63-2
2,375, 62-22,776, JP-A-1-95,
117), phosphate ester polymer (Japanese Patent Laid-Open No. 61-25 / 1986)
6,573) is effective. Furthermore, there is also a method of adding polyacrylonitrile to an electrolytic solution (Japanese Patent Laid-Open No. 62-27).
8,774). In addition, a method using both an inorganic and an organic solid electrolyte is also known (JP-A-60-1768).

The separator has a high ion permeability,
An insulating thin film having a predetermined mechanical strength. Olefin-based nonwoven fabrics such as polypropylene and glass fibers are used because of their organic solvent resistance and hydrophobicity. It is known that the following compounds are added to an electrolyte for the purpose of improving discharge and charge / discharge characteristics. For example, pyridine (JP-A-49-108,525), triethylphosphite (JP-A-47-4,376), triethanolamine (JP-A-52-72,425), cyclic ether (JP-A-57-725,425) 152,684), ethylenediamine (Japanese Patent Application Laid-Open No. 58-87,777), n-glyme (Japanese Patent Application Laid-Open No. 58-87,778), hexaphosphoric triamide (Japanese Patent Application Laid-Open No. 58-87,779), nitrobenzene derivative (Japanese Patent Application Laid-Open No. 58-214, 281), sulfur (Japanese Unexamined Patent Application Publication No.
80), quinone imine dyes (JP-A-59-68,18)
4), N-substituted oxazolidinone and N, N'-substituted imidazolidinone (JP-A-59-154778), ethylene glycol dialkyl ether (JP-A-59-20)
5,167), quaternary ammonium salts (JP-A-60-3)
0,065), polyethylene glycol (JP-A-60-1985)
41,773), pyrrole (JP-A-60-79,67).
7), 2-methoxyethanol (JP-A-60-89,0)
75), AlCl ₃ (JP-A-61-88,466), a monomer of a conductive polymer electrode active material (JP-A-61-16)
1,673), triethylene phosphoramide (JP-A-6
1-208,758), trialkylphosphine (JP-A-62-80,976), morpholine (JP-A-62-80,976).
80,977), aryl compounds having a carbonyl group (JP-A-62-86,673), hexamethylphosphoric triamide and 4-alkylmorpholine (JP-A-6-8663).
2-217,575), bicyclic tertiary amines (Japanese Unexamined Patent Publication No.
2-217,578), oil (JP-A-62-287,
580), quaternary phosphonium salts (JP-A-63-121,
268), tertiary sulfonium salts (JP-A-63-121,
269).

Further, in order to make the electrolytic solution nonflammable, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride chloride can be contained in the electrolytic solution. (Japanese Patent Laid-Open No. 48-36,
632) Carbon dioxide can be included in the electrolyte to make it suitable for high-temperature storage. (JP-A-59-1
34, 567) Further, the positive electrode active material can contain an electrolytic solution or an electrolyte. For example, the ionic conductive polymer and nitromethane (JP-A-48-3663)
3) and addition of an electrolytic solution (JP-A-57-124870) are known.

Further, the surface of the positive electrode active material can be modified. For example, the surface of a metal oxide is treated with an esterifying agent (JP-A-55-163779), a chelating agent (JP-A-55-163780), and a conductive polymer (JP-A-5-163780).
8-163,188, 59-14, 274) and polyethylene oxide (JP-A-60-97,561).

Also, the surface of the negative electrode active material can be modified. For example, a method of providing an ion-conductive polymer or a polyacetylene layer (JP-A-58-111276);
iCl (JP-A-58-142,771) and treatment with ethylene carbonate (JP-A-59-31,573). As a carrier for the electrode active material, in addition to ordinary stainless steel, nickel, and aluminum, a porous foamed metal (JP-A-59-18,578) and titanium (JP-A-59-68,169) , Expanded metal (JP-A-61-264,686), punched metal, and negative electrode include porous nickel (JP-A-58-18, JP-A-58-18) in addition to ordinary stainless steel, nickel, titanium, and aluminum.
883), porous aluminum (JP-A-58-38,4).
66), aluminum sintered body (JP-A-59-130,0)
74), a molded product of an aluminum fiber group (Japanese Unexamined Patent Publication No.
48,277), the surface of stainless steel is silver-plated (JP-A-60-41,761), calcined carbonaceous materials such as phenol resin calcined bodies (JP-A-60-112,264), Al
-Cd alloy (JP-A-60-211,779), porous foamed metal (JP-A-61-74,268) and the like are used.

The current collector may be any electronic conductor that does not cause a chemical change in the constructed battery. For example, in addition to commonly used stainless steel, titanium, aluminum and nickel, a nickel-plated copper (Japanese Patent Laid-Open No.
8-36,627), a titanium-plated copper body, and a sulfide positive electrode active material are treated with copper on stainless steel (Japanese Patent Application Laid-Open No. Sho.
0-175, 373).

The shape of the battery can be applied to any of coins, buttons, sheets, cylinders, squares and the like.

[0030]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the present invention. Example 1 87 parts by weight of V ₆ O ₁₃ as a positive electrode active material and 10 parts by weight of acetylene black as a conductive agent were mixed, and 3 parts by weight of a solid content of the polymer of the present invention was further dissolved as a binder. And kneaded, and applied to both surfaces of a 20 μm-thick aluminum foil current collector. As a solvent for the solution, a solvent in which a binder such as N-methylpyrrolidone, xylene, and toluene was soluble was used. The coated material was dried and compression-molded by a roller press to prepare a belt-shaped positive electrode sheet (1). FIG. 1 shows the positive electrode sheet 1. The thickness of the positive electrode sheet after compression molding was 220 μm. Table 1 shows the binder of the present invention used and the binder of the comparative example.

A negative electrode sheet (2) was prepared by cutting a lithium-aluminum alloy (alloy ratio: 80-20% by weight, thickness: 150 μm) into a belt shape. The positive electrode (1), the microporous polypropylene film separator (3), the negative electrode sheet (2) and the separator (3) are laminated in this order,
This was spirally wound.

The wound body was housed in a nickel-plated iron bottomed cylindrical battery can (4) also serving as a negative electrode terminal. Further, 1 mol / liter LiB is used as an electrolyte.
F ₄ (a mixture of equal volumes of propylene carbonate and 1,2-dimethoxyethane) was injected into the battery can. A battery lid (5) having a positive electrode terminal was caulked via a gasket (6) to produce a cylindrical battery. The positive electrode terminal (5) was connected to the positive electrode sheet (1), and the battery can (4) was connected to the negative electrode sheet by a lead terminal in advance. FIG. 1 shows a cross section of a cylindrical battery. In addition, 7 is a safety valve.

When the mixture was dropped from the positive electrode sheet when the wound body was formed, the ratio of the area of the dropped portion to the total area of the sheet was obtained, and the ratio of the mixture was dropped. In addition, the completed battery was discharged to 2.2 V at a current density of 1 mA / cm ² and then repeatedly charged to 3.4 V, and a charge / discharge cycle test was performed.
% Was defined as the charge / discharge cycle life. Table 1 shows the results.

[0034]

[Table 1]

Example 2 Pulverized coal-based pitch coke was used as a negative electrode active material, and 95 parts by weight of the pitch coke was added with 5 parts by weight of a polymer of the present invention or a comparative polymer as a binder, and toluene, N-methylpyrrolidone was added. A slurry prepared by adding an appropriate solvent such as a solvent and the like was applied to both surfaces of a copper foil current collector having a thickness of 20 μm. After drying the applied material, it was compression-molded by a roller press machine to prepare a 230 μm-thick negative electrode sheet.

88 parts by weight of LiCoO ₂ as a positive electrode active material and 9 parts by weight of acetylene black as a conductive agent were mixed, and 3 parts by weight of a polymer of the present invention or a comparative material were added as a binder, and toluene and N-methyl were added. A slurry obtained by adding a suitable solvent such as pyrrolidone and kneading the mixture to a thickness of 20
It was applied to both sides of a μm aluminum foil current collector. After the coated material is dried, it is compression-molded by a roller press machine to a thickness of 220.
A positive electrode sheet of μ was prepared.

Using the prepared positive electrode sheet and negative electrode sheet, a cylindrical battery was prepared in the same manner as in Example 1. A charge / discharge cycle test is performed under the conditions of a current density of 1 mA / cm ² , a charge end voltage of 4.2 V, and a discharge end voltage of 2.7 V, and the number of cycles when the discharge capacity decreases to 60% of the initial capacity is referred to as the charge / discharge cycle life. And Table 2 shows the polymers used and the test results.

[0038]

[Table 2]

Example 3 LiCoVO ₄ (lithium carbonate, cobalt oxide and vanadium pentoxide in air at 1000 ° C. for 24 hours)
87 parts by weight), 9 parts by weight of acetylene black as a conductive agent, and 4 parts by weight of a polymer of the present invention or a comparative polymer as a binder, and the same method as in Example 2. A negative electrode sheet was prepared. The thickness of the sheet was 200 μm.

The prepared negative electrode sheet and the negative electrode sheet of Example 2
Using the same positive electrode sheet as in Example 18, a cylindrical battery was produced in the same manner as in Example 1. A charge / discharge cycle test was performed at a current density of 1 mA / cm ² , a charge end voltage of 3.6 V, and a discharge end voltage of 1.8 V, and the number of cycles when the discharge capacity decreased to 60% of the initial capacity was defined as the charge / discharge cycle life. Table 3 shows the polymers used and the test results.

[0041]

[Table 3]

[0042]

As is clear from Examples 1, 2 and 3, the electrode using the binder of the present invention prevents the active material from falling off and charges and discharges the secondary battery of a non-aqueous electrolyte battery. The cycle life is quite long and the charge / discharge cycle characteristics are excellent. The electrode using the binder of the present invention may be only a positive electrode or a negative electrode, or may be used for both electrodes.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a general cylindrical battery.

[Explanation of symbols]

 1. 1. positive electrode Negative electrode 3. Separator 4. Battery can 5. Battery cover 6. Gasket 7. safety valve

Claims (1)

(57) [Claims] 1. A non-aqueous electrolyte battery comprising a positive electrode active material, a negative electrode active material, and an electrolyte having ionic conductivity,
A nonaqueous electrolyte battery comprising a polymer represented by the following general formula (I) as a binder in a positive electrode mixture and / or a negative electrode mixture. General formula (I) However, in the formula, R ¹ is a hydrogen atom or an alkyl group having 1 to ² carbon atoms, R ² is an alkyl group having 1 to 12 carbon atoms, and 6 to 6 carbon atoms.
12 represents an aryl group or an aralkyl group having 7 to 13 carbon atoms; R ³ represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms; R ⁴ and R ⁵ represent a hydrogen atom or an alkyl group having 1 to 12 carbon atoms; Represents an aryl group having 6 to 12 carbon atoms or an aralkyl group having 7 to 13 carbon atoms, x is 5 to 40% by weight, y is 40 to 90% by weight, and z is 1 to 20% by weight. Here, x + y + z = 100% by weight.