Nonaqueous electrolyte for secondary battery and nonaqueous-electrolyte secondary battery employing the same
An object is to provide a nonaqueous electrolyte and a nonaqueous-electrolyte secondary battery which have excellent discharge load characteristics and are excellent in high-temperature storability, cycle characteristics, high capacity, continuous-charge characteristics, storability, gas evolution inhibition during continuous charge, high-current-density charge/discharge characteristics, discharge load characteristics, etc. The object has been accomplished with a nonaqueous electrolyte which comprises: a monofluorophosphate and/or a difluorophosphate; and further a compound having a specific chemical structure or specific properties.
1. A nonaqueous electrolyte solution, comprising:
(1) an electrolyte;
(2) a nonaqueous solvent, which dissolves the electrolyte and comprises, based on a total volume of the nonaqueous solvent:
(A) from 5-10% by volume of at least one compound selected from the group consisting of dimethoxyethane, diethoxyethane, and ethoxymethoxyethane; and
(B) 90% by volume or more of a cyclic carbonate and an acyclic carbonate; and
(3) from 0.001-5% by mass, based on a total weight of the nonaqueous solvent, of LiPO 2 F 2 .
2. The nonaqueous electrolyte solution according to claim 1 , wherein the compound (A) is dimethoxyethane.
3. A nonaqueous-electrolyte secondary battery, comprising:
a negative electrode and a positive electrode, which are capable of occluding/releasing lithium ions; and
the nonaqueous electrolyte solution according to claim 1 .
4. The nonaqueous-electrolyte secondary battery according to claim 3 , wherein the negative electrode comprises a carbonaceous material.
5. The nonaqueous-electrolyte secondary battery according to claim 3 , wherein the negative electrode comprises a negative-electrode active material comprising at least one selected from the group consisting of a silicon atom, a tin atom, and a lead atom.