LITHIUM ION SECONDARY BATTERY

摘要

A lithium ion secondary battery (100) is provided with: a positive electrode collector (221); a positive electrode active material layer (223) that is held on the positive electrode collector (221); a negative electrode collector (241); and a negative electrode active material layer (243) that is held on the negative electrode collector (241) and covers the positive electrode active material layer (223). A separator base (265) which is formed of a porous resin sheet is interposed between the positive electrode active material layer (223) and the negative electrode active material layer (243). In addition, a heat-resistant layer (266) is held on the separator base (265). The heat-resistant layer (266) contains an inorganic filler, a binder and a thickening agent. The weight ratio of the binder to the thickening agent in the heat-resistant layer, namely the weight ratio P (binder/thickening agent) satisfies P < 7.2.