NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

摘要

A lithium ion battery 100 has a flat wound electrode assembly 20, a nonaqueous electrolyte, and a battery case 10. The nonaqueous electrolyte contains an electrically insulating inorganic aggregate 16 and is formed of an impregnating electrolyte that is impregnated into the flat wound electrode assembly 20 and a surplus electrolyte that is not impregnated into the flat wound electrode assembly 20. Letting the flat wound electrode assembly 20 be divided into a planar region P where the electrode surfaces are planar surfaces and a lower wound curved region RL which is positioned vertically downward from the planar region P and where the electrode surfaces are curved, a boundary plane B that includes the boundary between the planar region P and the lower wound curved region RL, the amount MO of the inorganic aggregate 16 included in a space which is below the boundary plane B and the amount MI of the inorganic aggregate 16 included in the impregnating electrolyte within the flat wound electrode assembly 20 satisfy the relationship MO > MI.