Separator for power storage device, and power storage device including same

A separator for a power storage device that comprises a substrate which is a polyolefin microporous membrane including a polyolefin as a main component, and a covering layer disposed on at least one surface of the substrate, wherein:

• the covering layer comprises an inorganic filler and polymer particles of a thermoplastic polymer,
• the amount of polymer particles in the covering layer is 1 part by weight to 50 parts by weight with respect to 100 parts by weight of the inorganic filler in the covering layer,
• primary particles of the polymer particles have a mean particle size of from 1 μm to 10 μm,
• the polymer particles include polymer particles protruding from the covering layer, to at least 0.1 times the thickness of the inorganic filler portion of the covering layer, and
• the separator satisfies at least one of the following features (i) to (v):
• (i) the covering layer is formed in an inclined manner so as to be thicker toward the protruding polymer particles;
• (ii) at least 20% of the protruding polymer particles contact with the surface of the substrate;
• (iii) the covering layer has 180° peel strength from the substrate of 200 gf/cm or greater;
• (iv) the average number of protruding polymer particles adjacent to any one protruding polymer particle is less than 2;
• (v) the ratio of the mean particle size of the protruding polymer particles with respect to the mean particle size of the inorganic filler is greater than 10.