Nonaqueous solvent, and nonaqueous electrolyte solution and nonaqueous secondary battery that use nonaqueous solvent

A nonaqueous solvent for a nonaqueous secondary battery, comprising:

• at least one fluorinated cyclic carbonate (A) selected from the group consisting of a fluorinated cyclic carbonate represented by Formula (I) below and a fluorinated cyclic carbonate represented by Formula (II) below;
• and
• a fluorinated phosphazene (B) represented by Formula (III) below:
• (wherein F represents fluorine, and X1 and X2 each independently represent hydrogen, fluorine or a C1-4 alkyl group),
• (wherein F represents fluorine, Y1 and Y2 each independently represent hydrogen, fluorine or a C1-4 alkyl group, R1 and R2 each independently represent hydrogen, fluorine or a C1-4 alkyl group, and n is an integer from 1 to 3),
• (wherein P represents phosphorus, N represents nitrogen, at least one of Z1 and Z2 represents fluorine while the other one of Z1 and Z2 independently represents hydrogen, a C1-4 alkoxy group or a phenoxy group, and m is an integer from 2 to 10;
• a ratio of the number of fluorine atoms to the number of phosphorus atoms in Formula (III) [number of fluorine atoms/number of phosphorus atoms] is 4/3 or more;
• and the fluorinated phosphazene represented by Formula (III) may be either chain or cyclic).