PURPOSE: To improve utilization factor of an active material, and to improve gas absorption characteristic by adding polyvinyl alcohol and a surface active agent to a porous body mainly consisting of polyolefine.
CONSTITUTION: Polyvinyl alchol and a surface active agent are added to a porous body mainly consisting of polyolefine, which is a primary component of a separator. As the porous body mainly consisting of polyolefine, those made of polyethylene or polypropylene are generally used, and a nonwoven fabric of polyethylene or polypropylene is used in consideration of heat resistance and cost. A nonwoven fabric, to which a part of a fabric having electrolyte affinity, such as polyamide fiber, is added can be used to improve electrolyte affinity. The surface active agent indicates its characteristic of holding sufficient electrolyte in a separator at the time of injecting the electrolyte, and thereafter, dissipation of the electrolyte from the separator is prevented by the polyvinyl alcohol, and the excellent property of the electrolyte can be maintained for a long period. High capacity can thus be maintained for a long time.
YAMAMURA KOJI
SERI HAJIME
TSUJI YOICHIRO
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