TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The non-aqueous organic solvent is a carbonate, an ester, ether, or a ketone. The carbonate is dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, methylethyl carbonate, ethylene carbonate, propylene carbonate, or butylene carbonate. The electrolyte comprises a mixed solvent of a cyclic carbonate and a chain carbonate. The electrolyte comprises a mixed solvent of a carbonate solvent and an aromatic hydrocarbon solvent. The aromatic hydrocarbon solvent is benzene, fluorobenzene, toluene, trifluorotoluene, and/or xylene. Preferred Ratio: The carbonate solvent and the aromatic hydrocarbon solvent are mixed in a volume ratio of 1:1-30:1.    TECHNOLOGY FOCUS - POLYMERS - Preferred Component: The poly(ester)(meth)acrylate is a polymer derived from a (polyester)polyol with greater than or equal to 3 hydroxyl groups optionally substituted with a (meth)acrylic ester, and the remaining portion of the hydroxyl group that is unsubstituted with the (meth)acrylic ester is substituted with a group having no radical reactivity. The (polyester)polyol is trialkylol, glycerol, or erythritol. The (meth)acrylic ester is of formula -OC(=O)(CH2)n'OC(=O)CH=CH2, or -OC(=O)(CH2)n'OC(=O)C(CH3)=CH2. The group having no radical reactivity is 1-20C aliphatic hydrocarbon, 5-20C aromatic hydrocarbon, 1-20C ether, or 1-20C ester. The group having no radical reactivity is of formula -OC(=O)(CH2)3CH3, -OC(=O)Ar', -OC(=O)(CH2)n'O(CH2)n'CH3, -O(C=O)(CH2)n'OC(=O)(CH2)n'CH3, and -(C=O)CH=CH2. The composition for a polymer electrolyte further comprises a base catalyst.n'=1-20; andAr'=optionally substituted aromatic hydrocarbon.Preferred Method: The solid polymer electrolyte is heat-treated at 40-110 degrees C, or UV-radiated to polymerize the poly(ester)(meth)acrylate or the polymer of a poly(ester)(meth)acrylate. Preferred Definitions:    R1=-CH3, -C2H5, or -OCH3.    EXAMPLE - About 1 mole dipentaerythritol and 2 moles epsilon -caprolactone was added to a toluene solvent. A tetrapropyltitanate catalyst (0.01 wt.%) was added, and reaction was carried out at 50 degrees C to synthesize a dipentaerythritol monomer, where a portion of hydroxyl groups was substituted with epsilon -caprolactone. About 1 mole dipentaerythritol monomer, 4 moles acrylic acid, and 2 moles butylcarbonic acid were reacted to obtain a polyester hexaacrylate compound. Ethylene carbonate/ethyl methyl carbonate/propylene carbonate/fluorobenzene was mixed in a volume ratio of 30/55/5/10 to prepare an organic mixed solvent. About 1.15 M lithium hexafluorophosphate were added to the solvent, and an electrolyte additive including 3 wt.% chloroanisole and 3 wt.% polyester hexaacrylate compound, was further added to the solution to prepare a composition to form an electrolyte.