Secondary battery with graft-polymerized separator

Claim 2

A secondary battery comprising a positive-electrode active material enabling the battery to discharge and to be charged, an electrolyte solution, a separator, and a negative-electrode active material enabling the battery to discharge and to be charged, wherein said separator is obtained by subjecting a porous polymer substrate to plasma treatment and polymerizing a monomer in the presence of the plasma-treated substrate thereby to graft-polymerize the monomer onto the substrate.

Claim 3

A secondary battery as claimed in claim 1, wherein said monomer contains a group capable of dissolving in the electrolyte solution.

Claim 4

A secondary battery as claimed in claim 1, wherein said monomer comprises at least one member selected from the group consisting of: a compound represented by the following general formula (1): ##STR9## wherein R 1 represents a hydrogen atom or an alkyl group, R 2 represents --C(O)--X 1 --(CH 2 CH 2 O) n --R 3 , --C(O)--Y--(CH 2 ) x --C 6 H 5 , or --CN, in which X 1 and Y represent an oxygen atom or --N(R 4 )--, with R 4 being a hydrogen atom or an alkyl group, n is an integer, R 3 represents a hydrogen atom, an alkyl group having from 1 to 3 carbon atoms, an aralkyl group, or an aryl group, and x is an integer; a compound represented by the following general formula (2): ##STR10## wherein R 5 represents a hydrogen atom or an alkyl group, X 2 represents --C(O)--X 3 --C(O)--, in which X 3 represents --O--X 4 --O--or --O--(CH 2 CH 2 O) m --, with X 4 being an alkylene group and m being 1 or more; and, a compound represented by the following general formula (3): ##STR11## wherein R 6 represents a hydrogen atom or an alkyl group, R 7 represents an alkyl group or --CH 2 O--R 8 , in which R 8 represents a hydrogen atom or an alkyl group.