HYDROPHILIC SUPPORT MATERIAL FOR SOLID ELECTROLYTIC FILM

PROBLEM TO BE SOLVED: To reduce the electric resistance of a solid electrolytic film without damaging the mechanical strength of the film by constituting a support material for solid electrolytic film by use of a perfluorocarbon polymer system having a surface water contact angle of a specified value. SOLUTION: As a support material such as woven fabric or nonwoven fabric, a fluorinated compound having large electric negative degree and satisfactory heat resistance and solvent resistance by small atom diameter, particularly, a perfluorocarbon polymer system such as polytetrafluoroethylene having high strength and chemical inactivity is used. Its surface water contact angle is set to 0-90 deg. by a surface treatment, for example, corona discharge or plasma emission to improve the hydrophilicity. This support is embedded between layers to form a laminated film of two layers or more. It is firmly bonded to a fluorine-containing polymer having a functional group such as sulfonic group or carboxylic group to retain the mechanical strength, and the ion conductivity on the surface is enhanced because of the improvement in wettability with electrolyte and the retaining of an ion-exchange group. A temporary reinforcing member such as general fiber which is removable with any bad influence may added thereto.