Sony Corporation

Takao Nirasawa

Atsuo Omaru

Hidetoshi Ito

A secondary battery which exhibits less deterioration of capacity, can maintain high energy densities in high temperature atmospheres, and has high practicality, and an electrolyte used therefor, are provided. The electrolyte contains an anion expressed by (PFQR), so degradation of the electrolyte can be prevented. In the formula, Q expresses at least one of CF, CF, and CF, and R expresses SOCFand/or SOCF. a, b and c satisfy 1&#x2266;a&#x2266;5, 0&#x2266;b&#x2266;5, and, 0&#x2266;c&#x2266;5, respectively. Furthermore, an anion expressed by N(CFSO)is contained, which can further prevent the degradation of the electrolyte. In the formula, n satisfies 1&#x2266;n&#x2266;2. Therefore, the capacity recovery rate after storage and heavy load discharge maintenance rate are high even in high temperature atmospheres, and high reliability can be obtained.

Secondary battery and electrolyte used therefor

A nonaqueous electrolyte secondary battery includes a positive electrode having a positive electrode active material, a negative electrode containing a negative electrode active material capable of being doped/undoped with lithium, and a nonaqueous electrolyte. The nonaqueous electrolyte contains at least one of thiols, thiophenes, thioanisoles, thiazoles, thioacetates, aromatic sulfones, and the derivatives thereof. The capacity of the battery is not significantly degraded after cycling and its cycle life is significantly long.

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Fukushima, Japan

Takao Nirasawa