Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Include electrolyte chemically specified and method
Patent
1985-04-17
1987-04-07
Walton, Donald L.
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Include electrolyte chemically specified and method
429213, 429232, H01M 1036
Patent
active
046561056
DESCRIPTION:
BRIEF SUMMARY
[FIELD OF TECHNOLOGY]
This invention relates to an iodine cell which uses iodine fixed by a polymer as a positive electrode active substance.
[BACKGROUND TECHNOLOGY]
Iodine is a substance which readily becomes an anion, and is one of suitable positive electrode active substances. Iodine is known to form charge transfer complexes with various organic compounds. The charge transfer complexes of iodine are composed of iodine (acceptor) and various electron donating organic compounds (organic donor component). Known electron-donating compounds include heterocyclic compounds such as phenothiazine and carbazole; polynuclear aromatic compounds such as pyrene and perylene; and organic polymers such as poly-2-vinylpyridine, polyacetylene, poly-p-phenylene, polythienylene, polypyrrole, polyethers, polyaniline, polyamides, polyvinyl alcohol, polyethylene, polypropylene and polystyrene.
Some cells are known in which such an iodine charge transfer complex (to be referred to as the iodine complex or simply the complex adduct) is used as a main component of a positive electrode material. Furthermore, the present inventors found that such organic polymers as urea-formaldehyde resin, polyurethane, polyacrylonitrile, polyacrylamide, polymethacrylamide, polyethers and melamine resins are effective as the organic donor component.
However, the cells which use such iodine complexes as positive electrode active substances have problems. They have a low output. As discharging proceeds, they lose iodine, and abruptly decrease in electrical conductivity. Consequently, the resistance of the positive electrode material increases very much, and the internal resistances of the cells increase remarkably.
When a positive electrode material composed of the iodine complex is used in a secondary cell, discharging causes most of iodine to come off from the positive electrode material. Hence, this constitutes a decisive defect in secondary cells, i.e. the defect that the positive electrode material usually becomes an insulator and makes it impossible to recharge the cells. This problem inevitably arises when using iodine complexes of polymers which are intrinsically insulators, such as polyamides, polyacrylonitrile, polyvinyl alcohol, polyethers and poly-2-vinylpyridine.
Furthermore, such cells have the defect of short service lives.
[BRIEF DESCRIPTION OF THE DRAWING]
FIG. 1 is a sectional view showing a preferred embodiment of the cell of this invention.
In the drawing, 10 represents a positive electrode; 20, a negative electrode; 30, an electrolyte; 40, a separator; 50 and 50', a support; 60, a packing; and 70, a lead wire.
[DISCLOSURE OF THE INVENTION]
According to this invention, there is provided a cell in which a complex adduct of iodine and a polymer having the ability to form a complex adduct with iodine and/or a composition comprising said polymer and iodine dispersed therein is used as a main component of a positive electrode material, said positive electrode material having a carbon dispersed therein.
As preferred polymers having the ability to form a complex adduct with iodine in this invention, there can, for example, be named polyacrylamide, polymethacrylamide, urea-formaldehyde resin, polyvinyl alcohol, polyvinyl acetate, aliphatic polyamides such as nylon-6, nylon-6,6, nylon-12, nylon-6,9 and nylon-6,10, wholly aromatic polyamides such as Kelvar (a trademark for a product of E. I. du Pont de Nemours and Co.), polyethylene, polypropylene, polystyrene, polyurethane, melamine resin, polyethers, polyacrylonitrile, Barex resin, polymethyl methacrylate, polytetramethylene ether, polyvinylpyrrolidone, poly-4-vinylpyridine, poly-2-vinylpyridine and poly-N-vinylcarbazole. The other known polymers described hereinabove can of course be used.
Two or more of these may be used as a blend, or a copolymer thereof may also be used.
In the cell of this invention, a carbon is included in a dispersed form in a positive electrode material composed of iodine and the polymer having the ability to form a complex adduct with iodine. A gener
REFERENCES:
patent: 3438813 (1969-04-01), Davis
patent: 3660163 (1972-05-01), Moser
patent: 3660164 (1972-05-01), Hermann et al.
patent: 3773557 (1973-11-01), Mead
patent: 4060673 (1977-11-01), Dey
patent: 4550064 (1985-10-01), Yen et al.
Kobayashi Sadao
Sukawa Hiroshi
Yamamoto Sadaaki
Mitsuit Toatsu Chemicals, Inc.
Walton Donald L.
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