NON-AQUEOUS ELECTROLYTE SOLUTIONS FOR RECHARGEABLE BATTERY NON-AQUEOUS ELECTROLYTE RECHARGEABLE BATTERY HAVING THE SAME

摘要

Provided is a novice and improved electrolyte for a non-aqueous electrolyte secondary battery, which is capable of increasing cycle lifetime while maintaining the concentration of free solvent of an electrolyte at a low value, and a lithium ion secondary battery using the electrolyte. According to the present invention, the electrolyte for a non-aqueous electrolyte secondary battery comprises: electrolyte salt with concentration of 2.0-5.0 M (mol/L); base solvent dissolving the electrolyte sa and cyclic carbonate-containing solvent including cyclic carbonate. The cyclic carbonate is included by 1-15 vol% with respect to the total volume of the base solvent and the cyclic carbonate, and the cyclic carbonate-containing solvent comprises coordinating solvent coordinated to an ion ionized in the electrolyte salt and free solvent uncoordinated to the ion ionized in the electrolyte salt. A total peak area ratio of the free solvent specified by Raman spectrum is 1-25%.