Tdk Corporation

Hirokazu Ohnuma

Masahiro Saegusa

Bungo Sakurai

A separator according to the embodiment includes a porous base material having a thermoplastic resin. The porous base material has a heat-resistant porous layer on at least one surface thereof. The heat-resistant porous layer contains inorganic particles, a resin, and sulfur. A lithium ion secondary battery according to the embodiment, includes: the separator interposed between a positive electrode and a negative electrode; and an electrolyte solution. The heat-resistant porous layer is disposed between the positive electrode and the porous base material. Sulfur is distributed unevenly in the heat-resistant porous layer so as to exist in larger amount near a surface thereof opposite to the porous base material.

Separator and lithium ion secondary battery including the same

The negative electrode is formed from silicon, an amount of heat generation in a negative electrode, which is measured by a differential scanning calorimeter within a range of 210 to 380&#xb0; C. during full charge, is 850 J/g or less, and a cyclic carbonate including ethylene carbonate and a chain carbonate which has a chemical formula expressed by R&#x2014;O&#x2014;CO&#x2014;OR, and in which Rand Rrepresent an alkyl group having a carbon number of 2 or more are used for an electrolytic solution.

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Tokyo, Japan

Hirokazu Ohnuma