ADDITIVE FOR NON-AQUEOUS LIQUID ELECTROLYTE, NON-AQUEOUS LIQUID ELECTROLYTE SECONDARY CELL AND NON-AQUEOUS LIQUID ELECTROLYTE ELECTRIC DOUBLE LAYER CAPACITOR

The present invention provides an additive for a non-aqueous electrolytic solution including a phosphazene derivative which is solid at 25 DEG C and represented by the following formula (1): (PNR2)n wherein R represents a monovalent substituent or a halogen atom; and n represents a number of 3 to 6. More particularly, the present invention provides a non-aqueous electrolytic solution secondary cell and a non-aqueous electrolytic solution electric double layer capacitor which contain the additive for the non-aqueous electrolytic solution, which have excellent self-extinguishability or flame retardancy, and resistance to deterioration, and which have low internal resistance and excellent conductivity due to low viscosity of the non-aqueous electrolytic solution.