| 摘要 |
PROBLEM TO BE SOLVED: To have excellent initial electrolyte wettability and being capable of keeping the excellent electrolyte wettability even after the elapse of a time due to the use of an electricity storage device, in a microporous film separator using a polyolefin-based resin as a skeleton material for an electricity storage device in which electrolyte is constituted by only an ionic liquid or only an ionic liquid and an electrolyte salt.SOLUTION: A separator for an electricity storage device is a microporous film which is obtained by melting and mixing a raw material composition consisting mainly of a polyolefin-based resin, inorganic powder and a plasticizer to form a film, molding to be thinned through rolling and drawing, and removing the plasticizer, and has a thickness of 10-100 μm, an average pore size of 0.01-0.5 μm and a porosity of 50-90%. The inorganic powder is hydrophilic inorganic powder having a BET specific surface area of 100 m/g or more and a hydrophobicity degree of 5% or less. The raw material composition contains a surfactant. The inorganic powder is 40-80 mass%, the surfactant (solid content) is 1-15 mass%, and the polyolefin-based resin is 20-60 mass%. |
