Solid battery

Details Solid battery Solid battery

1998-12-01

2001-02-20

Gupta, Yogendra (Department: 1751)

Chemistry: electrical current producing apparatus, product, and

Current producing cell, elements, subcombinations and...

Include electrolyte chemically specified and method

C429S304000, C429S307000

Reexamination Certificate

active

06190804

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a solid battery using a high-molecular weight solid electrolyte excellent in the ion conductivity.
BACKGROUND OF THE INVENTION
A solid battery using a high-molecular solid electrolyte has recently come into the limelight because the solid battery has the merits that the possibility of the occurrences of a liquid leakage, igniting, gas spouting, etc., is generally low as compared with a battery using a conventional electrolytic solution and can ensure a higher reliability about safety. However, because the electric conductivity of the solid electrolyte is relatively low as compared with that of a conventional electrolytic solution, the internal resistance of the solid electrolyte becomes high, when the solid electrolyte is used for a solid battery, only the battery having a very small capacity is obtained, which closes the application of a solid electrolyte for a thin and light solid battery having a high capacity.
To develop a high-capacity battery using a solid electrolyte, a solid electrolyte obtained by mixing an acryloyl-modified high-molecular compound having an alkylene oxide polymer chain, an electrolyte salt, and further a solvent optionally, and crosslinking the mixture by the action of heat, light, electron beams, etc., is proposed. As conventional techniques, there are, for example, a high-molecular solid electrolyte by a combination of a trifunctional polymer having a terminal acryloyl-modified alkylene oxide polymer chain, a low-molecular alkylene oxide copolymer, polyvinyl chloride, an electrolyte salt, etc., as described in Japanese Patent Laid Open No. 3-177409; a solid electrolyte by a combination of a terminal acryloyl-modified alkylene oxide copolymer, an inorganic ion salt, and an organic solvent such as propylene carbonate, etc., as described in Japanese Patent Laid Open No. 63-94501; and a solid electrolyte by a combination of a difunctional and/or monofunctional high-molecular compound having terminal acryloyl-modified alkylene oxide polymer chain and an electrolyte salt as described in Japanese Patent Laid Open No. 5-178948. However, these solid electrolytes are not always satisfactory ones from the view points of a high capacity and a high mechanical strength.
SUMMARY OF THE INVENTION
The present invention has been made under these circumstances, and an object of the present invention is to provide a high-performance solid battery having a high capacity, an improved stability of the performance, and also an excellent mechanical strength by using a novel solid electrolyte.
As the result of making various investigations for solving the above-described problems of the conventional solid batteries, the present inventors have discovered that by using a solid electrolyte obtained by adding specific ratios of a solvent and an electrolyte salt to a tetrafunctional terminal acryloyl-modified high-molecular compound having an alkylene oxide polymer chain made up of at least a specific number of monomer units and fixing the solvent by crosslinking the mixture by an actinic radiation such as light, electron, etc., and/or by heating, solid battery which is excellent in the mechanical strength and has an excellent performance such as the electric conductivity comparable to a conventional liquid electrolyte is obtained and accomplished the present invention.
That is, the solid battery of the present invention is a solid battery using a solid electrolyte obtained by dissolving a tetrafunctional high-molecular compound and an electrolyte salt in a solvent and crosslinking the solution by the irradiation of an activating radiation and/or by heating, wherein the solid electrolyte is one obtained by using a tetrafunctional terminal acryloyl-modified alkylene oxide polymer having a high-molecular chain represented by following formula (I) as the above-described tetrafunctional high-molecular compound, compounding the solvent with the polymer at a ratio of from 220 to 1,900% by weight to the above-described tetrafunctional high-molecular compound, and crosslinking the compounded mixture:
wherein R
1
and R
2
each represents a hydrogen atom or a lower alkyl group; R
3
represents a hydrogen atom or a methyl group; m and n each represents an integer of at least 0; in each high-molecular chain, m+n≧35; and each of plural R
1
, R
2
, R
3
, m, and n in the four high-molecular chains may be the same or different.
The solid battery of the present invention, as shown embodied as a test cell in
FIG. 1
, has a composite positive electrode
2
made up of a positive electrode composite containing a positive electrode active substance and the solid electrolyte, and between the composite positive electrode
2
and a negative electrode
4
, the solid electrode can exist as a separator
3
in the solid battery of the present invention. In this case, as the negative electrode
4
, a composite negative electrode made up of a negative electrode composite containing a negative electrode active substance and the solid electrode can be used. The test cell further includes a charge collectors
1
and
5
, and leads
6
and
7
.
As the solvent, one or more kinds selected from the group consisting of cyclic esters, cyclic carbonic esters, cyclic ethers, nitrites, chain ethers, chain carboxylic esters, chain carbonic esters, sulfolane, sulfolane derivatives, dimethyl sulfoxide, N,N-dimethylformamide, and N-methyloxazolidinone are preferably used.


REFERENCES:
patent: 5436090 (1995-07-01), Kono et al.
patent: 5527639 (1996-06-01), Noda et al.
patent: 63-094501A (1988-04-01), None
patent: 3-177409A (1991-08-01), None
patent: 5-178948A (1993-07-01), None

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