Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2001-12-31
2004-03-16
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S539000, C525S540000, C524S555000, C524S538000, C524S606000, C524S608000, C524S438000
Reexamination Certificate
active
06706823
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to polymer gels with conducting capabilities.
Storage cells that can provide power for electronic apparatus, particularly portable apparatus, such as cell phones, notebook computers, and photographic equipment, have become regular necessities of the modern world. Lithium secondary cells for such a product have become increasingly popular. As a cathode, lithium cobalt oxide, lithium nickel oxide, and lithium magnesium oxide have been used. As an anode, lithium metal or carbon alloys are often used. A liquid electrolyte is also typically used. A damaged cell may leak liquid electrolyte, rendering the power cell useless and potentially damaging the electronic apparatus. Accordingly, solid polymer electrolytes have been investigated.
Considerable effort has been expended to provide solid or highly viscous polymeric electrolytes that contain a salt and display mobility, under appropriate conditions, of at least some of the ionic species present. In fact, polymer salt complexes and polymer salt plasticizing agents with good conductivity levels have been made. However, these compounds generally demonstrate conductivity levels too low for commercial applications.
It would therefore be desirable to develop an easily formed conductive polymer gel that demonstrates high ionic conductivity.
SUMMARY OF THE INVENTION
The present invention provides a conductive polymer gel including a copolymer having alkenyl monomer units, preferably selected from vinyl-substituted aromatic hydrocarbon, R
1
R
2
ethylene, and/or alkyl vinyl ether, and maleimide monomer units. The composition further includes a crosslinking agent and an electrolyte solution containing at least one inorganic salt. The conductive soft polymer gel has a current resistance less than or equal to 10
−4
&OHgr;, preferably less than or equal to 10
−5
&OHgr;.
A method for forming a conductive polymer gel is provided. The method includes forming a copolymer having alkenyl monomer units and maleimide monomer units, crosslinking the copolymer, and mixing the copolymer with an electrolyte solution.
The present invention also provides an electrolytic cell. The electrolytic cell includes an anode, a cathode, and a polymer gel. The polymer gel includes a copolymer with alkenyl monomer and maleimide monomer units, a multi-functional crosslinking agent, and an electrolyte solution containing at least one inorganic salt.
The following definitions apply herein throughout unless a contrary intention is expressly indicated:
“vinyl aromatic hydrocarbon” and “alkenyl benzene” are used interchangeably;
“maleic anhydride” encompasses dicarboxylic acids, including maleic anhydride that can form a copolymer with an alkenyl benzene, an R
1
R
2
ethylene, or an alkyl vinyl ether, the copolymer having dicarboxylic acid units capable of reaction with an amine functional group;
“maleimide” encompasses the reaction product of an amine and the dicarboxylic acids described above;
“R
1
R
2
ethylene” encompasses compounds of the general formula:
where R
1
and R
2
are the same or different substituents on the same or different carbon atoms of the ethylene group, and are independently H or substituted C
1
-C
20
alkyl groups; and
poly(alkenyl-co-maleimide) includes, for example, poly(alkenylbenzene-co-maleimide), poly(R
1
R
2
ethylene-co-maleimide), and poly(alkyl vinyl ether-co-maleimide).
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
The conductive polymer gel composition of the present invention includes a copolymer, an electrolyte solution, and a crosslinking agent. The copolymer is a poly(alkenyl-co-maleimide), the electrolyte solution contains an inorganic salt, and the crosslinking agent is a multi-functional organic compound.
The poly(alkenyl-co-maleimide) contains alkenyl contributed monomer units chosen from vinyl-substituted aromatic hydrocarbon, R
1
R
2
ethylene, and/or alkyl vinyl ether. The copolymer further includes maleimide contributed monomer units.
Poly(alkenyl-co-maleimide) and poly(alkenyl-co-maleic anhydride) encompass random and stereospecific copolymers, including copolymers having a backbone with alternating alkenyl-contributed units (i.e., monomer units derived from an alkenyl group such as styrene) and maleimide- or maleic anhydride-contributed units (i.e., monomer units derived from a maleimide or a maleic anhydride). Such alternating structures typically are described as poly(alkenyl-alt-maleimide) and poly(alkenyl-alt-maleic anhydride); however, these polymers are encompassed within the terms poly(alkenyl-co-maleimide) and poly(alkenyl-co-maleic anhydride). Exemplary copolymers include copolymers with a ratio of about 50% alkenyl contributed monomer units and about 50% maleimide contributed monomer units. However, copolymers with at least about 20% alkenyl contributed monomer units are contemplated for use.
Preferred vinyl-substituted aromatic hydrocarbon contributed monomer units of a poly(alkenylbenzene-co-maleimide) are preferably derived from one or more of styrene, &agr;-methylstyrene, 1-vinyl-naphthalene, 2-vinyl-naphthalene, 1-&agr;-methyl vinyl naphthalene, 2-&agr;-methyl naphthalene, as well as alkyl, cycloalkyl, aryl, alkaryl, and aralkyl derivatives thereof, in which the total number of carbon atoms in the combined hydrocarbon is generally not greater than 18, as well as any di- or tri-vinyl aromatic hydrocarbons. Preferred vinyl aromatic hydrocarbons include styrene and/or &agr;-methyl styrene.
Preferred R
1
and R
2
groups of R
1
R
2
ethylene contributed monomer units and the alkyl groups of said alkyl vinyl ether contributed monomer units are independently selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tredecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, cyclopropyl, 2,2-dimethylcyclopropyl, cyclopentyl, cyclohexyl, methoxymethyl, methoxyethyl, methoxypropyl, methoxybutyl, methoxypentyl, methoxyhexyl, methoxyoctyl, methoxynonyl, ethoxydecyl, ethoxymethyl, ethoxyethyl, ethoxypropyl, ethoxybytyl, ethoxypentyl, ethoxyhexyl, ethoxyheptyl, ethoxyoctyl, ethoxynonyl, ethoxydecyl, propoxymethyl, propoxyethyl, propoxypropyl, propoxybutyl, propoxypentyl, propoxyheptyl, propoxyoctyl, propoxynonyl, propoxydecyl, butoxymethyl, butoxyethyl, butoxypropoyl, butoxybutyl, butoxypentyl, butoxyhexyl, butoxygeptyl, butoxyoctyl, butoxynonyl, butoxydecyl, pentyloxymethyl, pentyloxyethyl, pentyloxypropyl, pentyloxybutyl, pentyloxypentyl, pentyloxyhexyl, pentyloxyoctyl, pentyloxynonyl, pentyloxydecyl, hexyloxymethyl, hexyloxyethyl, hexyloxypropyl, hexyloxybutyl, hexyloxypentyl, hexyloxyhexyl, hexyloxyheptyl, hexyloxyoctyl, hexyloxynonyl, hexyloxydecyl, heptyloxymethyl, heptyloxyethyl, heptyloxypropyl, heptyloxybutyl, hexyloxypentyl, heptyloxyhexyl, heptyloxyheptyl, heptyloxyoctyl, heptyloxynonyl, heptyloxydecyl, octyloxymethyl, octyloxyethyl, octyloxypropyl, octyloxybutyl, octyloxypentyl, octyloxyhexyl, octyloxyheptyl, octyloxyoctyl, octyloxynonyl, decyloxymethyl, decyloxyethyl, decyloxypropyl, decyloxybutyl, decyloxypentyl, decyloxyhexyl, decyloxyheptyl, 1-methylethyl, 1-methylpropyl, 1-methylbutyl, 1-methylpentyl, 1-methylhexyl, 1-methylheptyl, 1-methyloctyl, 1-methylnonyl, 1-methyldecyl, 2-methylpropyl, 2-methylbutyl, 2-bethylpentyl, 2-methylhexyl, 2-methylheptyl, 2-methyloctyl, 2,3,3-trimethylbutyl, 3-methylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 2,3,3,4-tetramethylpentyl, 3-methylhexyl, or 2,5-dimethylhexyl.
Preferred R
1
R
2
ethylene contributed monomer units of the poly(R
1
R
2
ethylene-co-maleimide) include alkenes such as ethylene, propylene, butylene, isobutylene, pentene, hexene, heptene, etc., as well as any di- or tri-alkene, or mixtures thereof, with preference given to isobutylene.
Preferred alkyl vinyl ether contributed monomer units of the poly(alkyl vinyl ether-co-maleimide) include any alkyl vinyl ether such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, and any other alkyl vinyl ethe
Foltz Victor J.
Hall James E.
Wang Xiaorong
Bridgestone Corporation
Lee Rip A.
McCollister Scott A.
Palmer Meredith E.
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