ELECTROLYTE SOLUTION FOR ELECTROCHEMICAL DEVICES, PLASTIC COMPOSITION, USE AND PRODUCTION METHOD

An electrolytic solution for an electrochemical device, including: a cation (C) that is a monovalent to trivalent metal ion; an anion (A); a solvent (SO) that is a compound having a molecular weight of 1,000 or less; and a polymer (P) that has a weight-average molecular weight of more than 10,000, wherein a content ratio of the solvent (SO) relative to 1 mol of the cation (C) is 0.5 to 4 mol, and a content ratio of the polymer (P) is 0.5% by weight or more. Also provided are a plastic composition, an electrode sheet, an insulating layer, and an electrochemical device including the electrolytic solution, as well as producing methods of these.