Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Include electrolyte chemically specified and method
Patent
1997-07-22
1998-08-04
Nuzzolillo, M.
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Include electrolyte chemically specified and method
252 622, 429 33, H01M 1040
Patent
active
057891060
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention concerns ion-conductive polymers which are useful as electrolytes in electrochemical devices such as rechargeable batteries and fuel cells.
BACKGROUND OF THE INVENTION
The production, storage, and distribution of energy are among the main concerns of modern industry and society. Thus, the efficient exploitation of energy sources that generate electricity on an intermittent basis, e.g. solar energy, wind and wave power, require the availability of low-cost, high-efficiency electricity storage systems. Similarly, the increasingly widespread use of various portable electronic devices and appliances having fairly high power requirements, such as mobile telephones, portable music and video systems (compact cassette recorders/players, CD-players, video camcorders etc.), laptop computers and the like, has increased the number of rechargeable battery units in use by a significant factor. Finally, the desire to reduce urban air pollution has resulted in the development of electric automobile systems that have highlighted the shortcomings of existing battery systems with respect to price, power-to-weight ratio, and/or environmental concerns due to use of environmentally problematic materials such as heavy metals.
There have been a number of attempts at using ion-conductive polymers as electrolytes in batteries, i.a. in connection with the use of alkali metals as electrode material combined with the corresponding alkali metal cation as the charge carrier through the electrolyte. Lithium in particular is attractive for high-density batteries due to its low specific density, high standard potential and high melting point. Such attempts include the use of alkali metal salts such as LiClO.sub.4 solvated in a poly(alkylene oxide) matrix and the use of covalently bound ion-polymer complexes such as phenolate derivatives covalently bound to a poly(methyl hydrosiloxane) backbone.
In the case of solvated salt, the stability of the alkali metal electrode is believed to depend on the formation of a passivation layer which is due to an irreversible chemical reaction between the counter anion and the alkali metal electrode. However, despite relatively high ion conductivities of such electrolytes, the passivation phenomenon seriously limits the lifetime of the battery.
The passivation problem may be solved partially by covalently binding the anions to the backbone as has been done with the use of phenolates. However, although the anions are immobilized on the polymer matrix, these attempts have not resulted in electrolytes with ion conductivities of practically useful magnitude due to low dissociation constant of the lithium/phenolate ion pair and/or to the use of systems of inferior ion-solvating properties.
Consequently, there is a need for ion-conductive polymers that are stable in contact with the electrode materials and have ion conductivities of a magnitude that makes them practically applicable as electrolytes for inclusion into batteries or fuel cells.
SUMMARY OF THE INVENTION
It has now been found that surprisingly high ion conductivities can be obtained by means of polymers containing ion complexes comprising covalently bound carbocyclic anionic groups, the anion groups being aromatic and having been rendered aromatic as a result of the anion formation through the removal of at least one H.sup.+ ion. The aromatic, carbocyclic anionic groups may be substituted by various groups including electron-withdrawing groups.
In particular, the invention concerns an ion-conductive polymer containing covalently bound ion complexes of one of the formulas Ia-Ic ##STR1## wherein M.sup.+ is H.sup.+, Li.sup.+, Na.sup.+, or K.sup.+ ; --O.sup.-,M.sup.+ wherein M.sup.+ is as defined above; hydrogen, C.sub.1-5 alkyl, optionally substituted phenyl, phenylcarbonyl, or C.sub.1-6 alkanoyl; defined above; R.sup.7 is hydrogen, C.sub.1-5 alkyl, C.sub.2-5 alkenyl, C.sub.2-5 alkynyl, or optionally substituted phenyl; --CO--O--, or a group R.sup.7 --O--CO--O-- where R.sup.7 is as defined above; cyclo
REFERENCES:
patent: 5196484 (1993-03-01), Giles et al.
patent: 5350646 (1994-09-01), Armand et al.
patent: 5665265 (1997-09-01), Gies et al.
patent: 5681357 (1997-10-01), Eschbach
Patent Abstracts of Japan, vol. 15, No. 70, E-1035, Abstract of Japan, A, 2-291603 (Hitachi Maxell Ltd), 3 Dec. 1990.
Knutz Boye Cornils
Rosenmeier Lars
Danacell ApS
Nuzzolillo M.
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