Nonaqueous-electrolyte battery and battery assembly

A nonaqueous-electrolyte battery, comprising:

• a case,
• a positive electrode held in the case,
• a negative electrode held in the case and comprising a negative active material which undergoes lithium insertion/release at a potential higher than 1.0 V, and
• a nonaqueous electrolyte packed in the case, wherein the nonaqueous electrolyte comprises a nonaqueous solvent and an electrolyte material dissolved in the nonaqueous solvent, wherein the nonaqueous solvent comprises at least one compound (a) selected from the group consisting of poly(2-vinylpyridine) and poly(4-vinylpyridine) and
• at least one compound compound (b) is at least one compound selected from the group consisting of tris(trimethylsilyl)phosphate, bis(trimethylsilyl)methyl phosphate, dimethyl trimethylsilyl phosphate and a phosphate comprising at least one functional group represented by the formula (3):
• wherein R1 to R3 each independently represent an alkyl group having 1-10 carbon atoms, an alkenyl group having 2-10 carbon atoms, or an aryl group having 6-10 carbon atoms,
• wherein a content of the at least one compound (a) is from 0.01% to 3% by weight based on the total weight of the nonaqueous electrolyte, and
• wherein a content of the at least one compound (b) is from 0.1% to 20% by weight based on the total weight of the nonaqueous electrolyte.