Patent ID: 7229719

Claim:
A non-aqueous electrolyte secondary cell comprising: an anode including as an active substance a lithium complex oxide containing at least one transition metal; a cathode; a non-aqueous electrolyte in which an Li-salt is dissolved in an organic solvent as a supporting salt; and a separator between the anode and the cathode, wherein the organic solvent contains a phosphazene derivative represented by the following formula (1): wherein each of R 1 , R 2 and R 3 represents a monovalent substituent or a halogen element, X represents an organic group (3)(A) or (3)(C), and Y 1 , Y 2 and Y 3 independently represent a divalent connecting group, a divalent element or a single bond, provided that when Y 2 represents a divalent connecting group or a divalent element, Y 2 contains sulfur or selenium: wherein, when X is organic group (3)(A), each of R 5 and R 6 represents a monovalent substituent or a halogen element, Y 5 and Y 6 independently represent a divalent connecting group, a divalent element or a single bond, Z represents a divalent group or a divalent element, at least one of Y 5 , Y 6 and Z is oxygen, and wherein R 1 to R 3 , R 5 and R 6 are the same, wherein, when X is organic group (3)(C), each of R 8 and R 9 represents a monovalent substituent or a halogen element, Y 8 and Y 9 independently represent a divalent connecting group, a divalent element or a single bond, at least one of Y 8 and Y 9 is oxygen, and wherein R 1 to R 3 , R 8 and R 9 are the same, and wherein the organic solvent comprises from 15 to 60 vol % of a cyclic carbonic ester, from 10 to 80 vol % of a non-cyclic ester, and from 1.5 to 50 vol % of the phosphazene derivative.