NONAQUEOUS ELECTROLYTE SOLUTION FOR ELECTRICITY STORAGE DEVICES, AND ELECTRICITY STORAGE DEVICE USING SAME

The present invention provides a nonaqueous electrolyte solution for electricity storage devices, wherein: an electrolyte salt is dissolved in a nonaqueous solvent; a polyether polymer having an ethylene oxide unit, which has a weight average molecular weight of from 100,000 to 2,500,000, contains 0-50% by mole of a repeating unit derived from formula (1), 30-100% by mole of a repeating unit derived from formula (2), and 0-20% by mole of a repeating unit derived from formula (3); and the concentration of the polyether polymer is 0.01-2% by mass of the nonaqueous electrolyte solution. The Formula (1) is shown in the specification, wherein R represents an alkyl group having 1-12 carbon atoms or -CH2O(CR1R2R3); each of R1, R2 and R3 represents a hydrogen atom or -CH2O(CH2CH2O)nR4; the R1, R2 and R3 moieties may have different n and different R4 from each other; R4 represents an alkyl group having 1-12 carbon atoms or an optionally substituted aryl group; and n represents an integer of 0-12. The Formula (2) is sh