FIELD: electrical engineering. SUBSTANCE: proposed composition for electrochemical-cell plates, solid electrolyte, or separator has mixture of 1-95 mass percent of solid material, better inorganic solid with primary particles measuring 5 nm to 20 mcm and 5-99 mass percent of polymeric mass produced by polymerizing 5-100 mass percent in terms of condensation product mass of polyatomic alcohol, at least one compound capable of entering in reaction with carbonic or sulfonic acid, or their derivatives, or mixture of two or more of them, and at least one mole per mole compound of carbonic or sulfonic acid having at least one radically polymerized functional group, or their derivative, or mixture of two or more of them, and 0-95 mass percent in terms of mass of one compound having average molecular mass of at least 5000 with polyester segments in main or side chain, mass fraction of mixture in composition being 1 to 100 mass percent. EFFECT: enhanced mechanical strength and porosity of films obtained; enhanced resistance to short circuits. 5 cl, 1 tbl, 5 ex
