Patent ID: 8007938

Claim:
A non-aqueous electrolyte solution comprising: a lithium salt; at least one non-aqueous solvent selected from the group consisting of a chain carbonate, a cyclic carbonate, a chain carboxylic acid ester, a cyclic carboxylic acid ester, a chain ether and a cyclic ether; and a compound expressed by the following formula (IIa) wherein R 41 -R 52 independently of each other, represent a hydrogen atom, an alkyl group having 1-12 carbon atoms that may be substituted by a fluorine atom, an alkenyl group having 2-12 carbon atoms that may be substituted by a fluorine atom, an aryl group having 6-12 carbon atoms that may be substituted by a fluorine atom, or an aralkyl group having 7-12 carbon atoms that may be substituted by a fluorine atom, wherein each group R 41 -R 52 may have an ether linkage in its chain, and R 41 may be linked with R 42 , and R 43 may be linked with R 44 , to form a ring, said ring optionally comprising an oxygen atom.