JPS6398973A - Secondary battery - Google Patents

Abstract

PURPOSE:To obtain a secondary battery having high energy density by using alkali metal, alkali metal alloy, conductive polymer, or a composite of alkali metal or alkali metal alloy with conductive polymer in a negative electrode. CONSTITUTION:A negative electrode is formed with alkali metal, alkali metal alloy, conductive polymer, or a composite of conductive polymer with alkali metal or alkali metal alloy. A positive electrode is formed with a composite of conductive polymer with polymer electrolyte. The alloy used in the negative electrode is manufactured by both electrochemical and chemical processes, but the alloy manufactured by electrochemical process is preferable. Thereby, energy density is high, self-discharge rate is low, and discharge voltage is made flat.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a secondary battery that has high energy density, low self-discharge rate, long cycle life, and good charge/discharge efficiency (Coulombic efficiency). .

[Prior art] A polymer compound (conjugated polymer) that has a conjugated double bond in its main chain? The so-called polymer battery used for the i-electrode is expected to be a high energy density secondary battery. There have already been many reports regarding polymer batteries, such as those published by B.G. Nigley, Journal of the Chemical Society, and Chemical Communication.

1919, page 594 (P, J, Nigre
y et al., J.C.S., chem.

Commun, , Yu Wangwu 594), Journal
Electrochemical Society, 1981, p. 1651 (J, EIelectrochem, Soc.
,, 198j1651), [A.G. Matsuku Diarmid et al., Polymer Preprints, Vol. 25, No. 2. No. 248 (1984) (A, G, Ha
cDiarmid et atlPolymerPrc
prints, 25-412.2480984)),
Sasaki et al., 50th Conference Abstracts for the Electrochemical Society, 123.
(1983), Proceedings of the 51st Conference of the Electrochemical Society, 228.
(1984) ), JP-A-56-136469,
No. 57-121168, No. 59-3810, No. 5
No. 9-3872, No. 59-3873, No. 59-196
No. 566, No. 59-196573, No. 59-2033
No. 68, No. 59-203369, etc. can be mentioned as some of them.

[Problem that the invention seeks to solve]

However, in a polymer battery using the above conjugated polymer as an electrode, (1) high energy density, (B) low self-discharge,
It has not been possible to obtain anything that simultaneously satisfies high charge/discharge efficiency and (1) long cycle life.

In order to obtain a secondary battery that satisfies the above four battery performances at the same time, the inventors of the present invention have conducted various studies on electrode materials, and have found that, for example,
, 612 (1986)), [Hosaen et al., Abstracts of the 53rd Electrochemical Society of Japan Conference, D 121 (1986)], etc., the polymer electrolyte and the conjugated polymer having a conjugated double bond in the main chain. found that the complex was extremely effective.

The present invention was developed based on the above discovery, and an object of the present invention is to provide a secondary battery that is excellent in all of the above four battery characteristics.

(Means for Solving the Problems) The present invention has been made to achieve the above object, and its gist is that in a secondary battery consisting of a positive electrode, a negative electrode, and a non-aqueous electrolyte, the negative electrode is (1) made of an alkali metal. , Oi) a substance selected from alkali metal alloys, 080 conductive polymers, and (to) complexes of conductive polymers and alkali metals or alkali metal alloys; the positive electrode is a composite of a conductive polymer and a polymer electrolyte; It is located in a secondary battery consisting of the body.

[Specific structure and operation of the invention]

The present invention will be explained in detail below.

The negative electrode used in the secondary battery of the present invention is (1) an alkali metal, (B) an alkali metal alloy, a zero conductive polymer, or (
f) It is a composite of an alkali metal or an alkali metal alloy and a conductive polymer.

(1) Examples of alkali metals include Li, Ha, etc. (m) Examples of alkali metal alloys include LION alloy, Ll/HQ alloy, IJ/Zn alloy, Ll/Cd alloy,
u/sn alloys, Li/Pb alloys, and alloys of three or more metals containing alkali metals used in these alloys, such as i/Aj/l'+, Li/M/Sn, L
l/M/Pb, L+/AN/Zn, Li/AI/
Examples include Hg.

These alloys may be manufactured by either an electrochemical method or a chemical method, but those alloyed electrochemically are more preferable.

Further, examples of zero-conductivity polymers include polypyrrole, polygorole derivatives, polythiophene, polythiophene derivatives, polyquinoline, boriacene, polyparaphenylene, polyparaphenylene derivatives, polyacetylene, and the like. Furthermore, (g) composites of alkali metals or alkali metal alloys and conductive polymers include composites of Ll/M alloys and the above-mentioned various conductive polymers, such as polyparaphenylene or polyacetylene. Among these, preferred are, for example, polyacetylene,
Polyparaphenylene, Li/# alloy, Li/M
/- alloy, a complex of Ll//V alloy and boriacene or boriparaf-1-nylene. The term "composite" as used herein means a homogeneous mixture of an alkali metal or alkaline earth alloy and a conductive polymer, a laminate, and a modified product in which the base component is modified with the other component.

The conductive polymer used in the positive electrode of the secondary battery of the present invention is not particularly limited as long as it has a conjugated double bond in its main chain, but specific examples include boriacene, polyacenoacene, and polyacetylene.

Polyaniline, polycarbazolene, polyfuran, poly(1,6-hebutadiene)
, polyisothianaphthene, polyparaphenylene, polyparaphenylene sulfide, poly-berynaphthalene,
Polypyridazine, polypyrrole.

Examples include polyquinoline, polyselenophene, polythiophene, poly-(triphenylmethane) and derivatives thereof.

The polymer electrolyte used in the positive electrode of the secondary battery of the present invention is not particularly limited as long as it has a number average molecular weight of 500 or more and contains at least one carboxyl anion in the molecule, but usually, The following general formula is used.

[However, X and Y are hydrogen atoms or alkyl groups having 10 or less carbon atoms, and Z is -cco-, -oso3- or -
3 (with hr, a and b are 0 or a positive integer of 10 or less, Q is a methylene group (-Ct+2-) or a phenylene group (→(D→), n is a positive integer of 3 or more). ] These polymer electrolytes, for example, have a number average molecular weight of 5.
00 or more polyacrylic acid anions, polymethacrylic acid anions, polyvinylsulfonic acid anions, polyallylsulfonic acid anions, polystyrene sulfonic acid anions, and the like.

There are no particular restrictions on the seedlings of the polymer electrolyte to be composited with the conductive polymer, but usually 1 to 500 parts of the polymer electrolyte, preferably 2 to 20 parts of the polymer electrolyte per 100 parts of the conductive polymer.
011 parts by weight, particularly preferably 4 to 100 parts by weight.

Various methods can be considered for producing the composite used for the positive electrode of the secondary battery of the present invention, but usually, the leading polymer is chemically or electrochemically prepared in the presence of a polymer electrolyte using a known method. It can be obtained by synthetically. At this time, it is desirable that the polymer electrolyte be dissolved in the polymerization solution, but it may be in the form of a slurry in which it is not dissolved.

The electrode of the secondary battery of the present invention may be mixed with other suitable conductive materials, such as carbon black, acetylene black, metal powder, metal fiber, carbon 11111, as is well known to those skilled in the art. . Further, it may be reinforced with a thermoplastic resin such as polyethylene, modified polyethylene, polypropylene, polytetrafluoroethylene, ethylene-propylene-dieneter polymer (EPDM), or sulfonated EPDM.

The supporting electrolyte of the electrolytic solution of the secondary battery of the present invention is an alkali metal salt. As the alkali metal of the alkali metal salt,
Mention may be made of the metals Ll, Na and K, with the metal L1 being particularly preferred.

Typical anion components of the supporting electrolyte include, for example, C
lO4-, PF5-, ASFs-.

ASF < −+ SO3CF3−, BF4−1 and B
Examples include R4 (wherein R is an alkyl group or aryl group having 1 to 10 carbon atoms).

As the alkali metal salt as a supporting electrolyte, for example, L
tPFs, LI3bF6, Li(JO4゜LIAS
Fs, CF3803Ll, LI3F4.

'B (BLJ)4. LIB (Et)z (BU)
2.

NaPF5, NaBF4. NaASFs.

NaB (Bu)4. KB (Bu)4, KASFs
Examples include, but are not necessarily limited to these. These alkali metal salts may be used alone or in combination of two or more.

The concentration of the alkali metal salt cannot be unconditionally defined because it varies depending on the type of material used for the positive and negative electrodes, the type of cathode, charging conditions, operating temperature, type of supporting electrolyte, type of organic solvent, etc.・Generally 0.5 to 10
It is preferably within the range of mol/J. The electrolyte may be homogeneous or heterogeneous.

Examples of organic solvents that can be used alone or in combination as a solvent for the electrolyte of the secondary battery of the present invention include the following.

Alkylene nitrile: e.g., crotonitrile (liquid range, -51.1°C to 120°C), 2 trialkyl borates, trimethyl borate, (CI-h O) 3 B (
Liquid range, -29.3°C to 67°C) 2 tetraalkyl silicates, tetramethyl silicate, (CH30)4S
i (boiling point, 121°C) nitroalkanes: e.g., nitromethane, CH3NO2 (liquid range, -17°C to 100.8°C) alkylnitrile: e.g., acetonitrile, CH3ON (
Liquid range, -45°C to 81.6°C) 2 dialkylamides, dimethylborumamide, 11cON (CH3)
2 (liquid range, -60,48°C to 149°C) Lactam: Example, N-methylpyrrolidone (liquid range, -16°C to 202°C) Two monocarboxylic acid esters, ethyl acetate (liquid range,
-83,6°C to 77,06°C) Orthoesters: Examples, trimethyl orthoformate, HC(OCH3)3 (boiling point, 103°C) Lactone two examples, γ-butyrolactone (liquid range, -42°C to 206°C) Dialkylnate, QC(OCH3)2 (liquid range, 2°C to 90°C) Alkylene carbonate: e.g., propylene carbonate, (liquid range, -48°C to 242°C) Monoether diside, diethyl ether (liquid range, -116 ℃~34,5℃) Polyether:
Examples, 1,1- and 1,2-dimethoxyethane (liquid range, -113.2°C to 64°C, 5°C and -58°C, respectively)
~83℃) 2 cyclic ethers, tetrahydrofuran (liquid range, -
65°C to 61°C): 1,3-dioxolane (liquid range,
-95°C to 78°C) 2 nitroaromatics, nitrobenzene (liquid range, 5.7°C to 210.8°C) Aromatic carboxylic acid halides: e.g., benzoyl chloride (liquid range, 0
℃~197℃), benzoyl bromide liquid range, -24℃
~218℃) Aromatic sulfonic acid halide: e.g., benzenesulfonyl chloride (liquid range, 14.5℃ ~
251°C) Aromatic phosphonic acid dihalide: Example, benzenephosphonyl dichloride (boiling point, 258°C) Aromatic thiophosphonic acid dihalide (2 parts), benzene thiophosphonyl dichloride (boiling point, 124°C at a pressure of 5.8 g) (melting point, 22°C) 3-methylsulfolane (melting point, -1°C) Alkyl sulfonic acid halide, methane sulfonyl chloride (boiling point, 161°C) Alkyl carboxylic acid halide: e.g., ahythyl chloride (liquid temperature, -112°C ~ 50.9°C), acetyl bromide (liquid range, -96°C to 16°C), propionyl chloride (
liquid range, -94°C to 80°C) two saturated heterocyclic compounds, tetrahydrothiophene (liquid range, -96°C to 12°C)
1°C) = 3-methyl-2-oxazolidone (melting point, 15
．． 9℃) dialkyl sulfamic acid halides, dimethyl sulfamyl chloride (boiling point, pressure 16#WH17 at 80℃) alkyl halosulfonate: e.g., ethyl chlorosulfonate (boiling point,
151°C) Two unsaturated heterocyclic carboxylic acid halides, 2-furoyl chloride (liquid range, -2°C to 113°C) Two five-membered unsaturated heterocyclic compounds, 1-mebruvirol (boiling point, 114°C)
), 2,4-dimethylthiazole (boiling point, 144°C),
Furan (liquid range, -85.65°C to 31.36°C), esters and/or hemagnides of di-salt carboxylic acids: e.g., ethyl oxalyl chloride (boiling point, 135°C), mixed alkylsulfonic acid halides /Carboxylic acid halides: Examples, chlorosulfonylacetyl chloride (boiling point, 98°C at pressure 10g to 11g), 2 dialkyl sulfoxides, dimethyl sulfoxide (liquid range, 18.4°C to 189°C) 2 dialkyl sulfates, dimethyl sulfate ”-1・(liquid range, −
31.75℃～188. 5℃) Dialkyl sulfide: Example, dimethyl sulfide (boiling point, 126℃) Alkylene sulfite side, ethylene glycol
Sulfide (liquid range, -11°C to 173°C) 2 halogenated alkanes, methylene chloride (liquid range, -173°C)
(95°C to 40°C) 1,3-dichloropropane (liquid range, -99.5°C to 120.4°C) Among the above, preferred organic solvents include sulfolane, crotonitrile, nitrobenzene, tetrahydrofuran, methyl-substituted tetrahydrofuran, 1, 3-dioxolane, 3-methyl-2-oxazolidone, propylene or ethylene carbonate,
Sulfolane, γ-buburolactone, ethylene glycol sulfite, dimethyl sulfide, dimethyl
sulfoxide, and 1,1- and 1,2-dimethoxyethane, and particularly preferred are mixed solvents of propylene carbonate and 1,2-dimethoxyethane, and mixed solvents of sulfolane and 1,2-dimethoxyethane. Because they appear to be the most chemically inert toward battery components and have a wide liquid range, they particularly allow for highly and efficient use of cathode active materials. It is from.

There are no particular limitations on the charging method for the secondary battery of the present invention, but it usually combines methods such as (1) constant current method, (M) constant voltage method, 0 pulse current charging, and (to) pulse voltage method, and the method described above. A combined method is used.

In the present invention, if necessary, a porous membrane made of a synthetic resin such as polyethylene or polypropylene or natural miscellaneous paper may be used as the diaphragm.

In addition, some of the electrodes used in the secondary battery of the present invention may react with oxygen or water and reduce the performance of the battery, so the battery should be sealed and substantially oxygen-free and water-free. It is desirable that the condition is as follows.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1 <Production of composite> 400 g of distilled water that had been deoxidized in advance was placed in a 1 J three-necked flask, and nitrogen gas was bubbled through it for about 1 hour while stirring. Thereafter, the inside of the system was placed under a nitrogen gas atmosphere, a thermometer and a condenser were attached, and then the flask was cooled with water and ice to bring the solution temperature to 15°C. To this, add aniline 20 (Co and polyvinyl sulfur I!2 (number average molecular weight is about 10,000)
Added 50g. Next, 220% ammonium persulfate was gradually added, while stirring and keeping the internal temperature below 25°C.
The reaction was allowed to proceed for 5 hours. After the reaction was completed, the greenish-brown reaction liquid was filtered and dried under vacuum to obtain a dark green product 15q. The resulting dark green product was immersed in 300 d of 10% aqueous ammonia, stirred overnight at room temperature, and then filtered. then 10001
After washing with distilled water (d), vacuum drying was performed at 80° C. for 15 hours.

After that, it was further immersed in 1,000 d of 1,2-dimethoxyethane, stirred at room temperature for 5 hours, filtered, and further immersed in 1,2-dimethoxyethane.
Wash with m 1,2-dimethoxyethane and incubate at 80°C for 15 min.
After vacuum drying for an hour, it was further dried at 220°C for 5 hours. Analysis of the sulfur atoms in the obtained yellow powder revealed that this polyaniline contained 23% by weight of polyvinyl sulfate or polyvinyl sulfate anion.

<Battery experiment> The powder of the composite of polyaniline and polyvinyl sulfate obtained by the above method was prepared using a known method to obtain a powder with a diameter of 2011III.
Lithium foil (thickness 200mm)
A battery was constructed using disk-shaped pieces with a diameter of 20 µm, which were cut from 20 μm, as active materials for the positive and negative electrodes, respectively.

FIG. 1 is a schematic cross-sectional view of a battery cell for measuring the characteristics of a secondary battery, which is an example of the present invention, in which 1 is a platinum lead wire for the negative electrode, 2 is a 0-electrode platinum wire with a diameter of 20 mm, and 80 meshes. , 3 is a negative electrode with a diameter of 20 m, 4 is a circular porous polypropylene diaphragm with a diameter of 201 m, and is thick enough to be sufficiently impregnated with the electrolyte, 5 is a disc-shaped positive electrode with a diameter of 20 ttm,
6 is a positive electrode platinum wire mesh current collector with a diameter of 20# and 80 mesh; 7
8 indicates a positive electrode lead wire, and 8 indicates a screw-type polytetrafluoroethylene container.

First, the positive electrode platinum wire mesh current collector 6 is placed in the lower part of the concave portion of the container 8, the positive electrode 5 is placed on top of the positive electrode platinum wire mesh current collector 6, a porous polypropylene diaphragm is placed on top of the positive electrode platinum wire mesh current collector 6, and the electrolytic solution is After sufficiently impregnating the battery, 9 layers 3 were stacked, and the negative electrode platinum wire current collector 2 was further placed thereon, and the container 8 was tightened to produce a battery.

The electrolyte was propylene carbonate and 1,2-dimethoxyethane (volume ratio: 1), which had been distilled and dehydrated according to a conventional method.
A 2 mol/1 solution of Li B F 4 dissolved in a mixed male medium of =1) was used.

Using the battery prepared in this way, the battery was used under a constant current (1
, 0 mA/IJ, and battery voltages ranging from 1.5 V to 4.0 V were repeatedly charged and discharged.

As a result, the discharge capacity was 192W per unit weight of active material.
h r, “Kytessu, mata, tll?li?fffi
The number of cycles until the tfim discharge capacity decreased to 50% (hereinafter referred to as "cycle life") was 671. Furthermore, when the battery was left charged for one week, its self-discharge rate was 4.6%.

Comparative Example 1 42wt% HB instead of polyvinyl sulfur 1509
Polyaniline was synthesized in exactly the same manner as in Example 1, except that 100 d of F 4 aqueous solution was added, and it was post-treated to form an electrode, and a battery experiment was conducted. As a result, the maximum discharge capacity of the battery was 153 W-hr/Kg, the cycle life was 407 times, and the self-discharge rate after 12 hours was 18
．． It was 5%.

Examples 2-4 Polyvinyl sulfate 50! A battery experiment was conducted in exactly the same manner as in Example 1 except that various polymer electrolytes were used in place of iF, and a maximum discharge capacity of 51° cycle life was obtained.
The self-discharge rate was measured after one week.

The results are shown in Table 1.

Example 5 A composite was manufactured in exactly the same manner as in Example 1, except that virol was used instead of aniline in <Production of Composite>. After molding into an electrode, a battery experiment was conducted. As a result, the maximum discharge capacity of this battery was 189W-hr/KL cycle life 611 times.

The self-discharge rate after one week was 5.3%.

Comparative Example 2 A composite was produced in exactly the same manner as in Example 1, except that polyvinyl sulfuric acid was used in <Production of Composite>, and a battery experiment was conducted. As a result, the maximum discharge capacity of this battery was 150 W-hr/9. Fj cycle life 325 times,
The self-discharge rate after one week was 20.1%.

Examples 6 to 8 Battery experiments were conducted in exactly the same manner as in Example 1, except that lithium was used instead of lithium as the negative electrode material. The results are shown in Table 2.

〔Effect of the invention〕

As described above, the secondary battery of the present invention has high energy density, low self-discharge rate, and good voltage flatness during discharge. Furthermore, the secondary battery of the present invention is lightweight, compact, and has a high energy density, making it ideal for use in portable devices, electric vehicles, gasoline vehicles, and power storage batteries.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a battery for measuring characteristics of a secondary battery, which is a specific example of the present invention. 1... Platinum lead wire for negative electrode 2... Platinum wire mesh current collector for negative electrode 3... i-electrode 4... Porous polypropylene diaphragm 5... Positive electrode 6... Platinum wire mesh current collector for positive electrode Body 7...Positive lead wire

Claims (1)

[Claims] In a secondary battery consisting of a positive electrode, a negative electrode, and a non-aqueous electrolyte, the negative electrode is (i) an alkali metal, (ii) an alkali metal alloy,
(iii) a conductive polymer and (iv) a composite of a conductive polymer and an alkali metal or an alkali metal alloy; Characteristic secondary batteries.