NOVELTY - A gel electrolyte (E1) comprises at least one poly(ethyleneoxide)siloxane, at least one crosslinking agent, at least one monofunctional monomeric compound, at least one salt, and/or at least one radical reaction initiator.    USE - In the preparation of an electrochemical cell e.g. lithium-ion rechargeable cell or a capacitor (claimed); in gel electrolyte systems as a conducting phase; as a solid polymer electrolyte (SPE).    ADVANTAGE - The gel electrolyte exhibits improved room temperature ionic conductivity, chemical electrochemical stability, high energy density, mechanical strength and inherent safety; has ability to configured in nearly any shape since the electrolyte contains no liquid; is a potentially inexpensive; exhibits cycling performance that limits their use to applications that do not require high rate performance.    DETAILED DESCRIPTION - A gel electrolyte (E1) comprises at least one poly(ethyleneoxide)siloxane of formulae Si(R1)(R2)(R3)(PEO1) (Ia), Si(R1)(R2)((PEO1)(PEO2) (Ib), Si(R1)(PEO1)(PEO2)(PEO3) (Ic) or Si(PEO1)(PEO2)(PEO3)(PEO4) (Id); at least one crosslinking agent; at least one monofunctional monomeric compound; at least one salt and/or at least one radical reaction initiator.    R1-R6=T1 or group of formulae Si(R4)(R5)(R6)(O)- (IIa), Si(R4)(R5)(PEO5)(O)- (IIb), Si(R4)(PEO5)(PEO6)(O)- (IIc) or Si(PEO5)(PEO6)(PEO7)(O)- (IId);    T1=1-12C alkyl, 2-12C alkenyl (both optionally substituted) or H;and    PEO1-PEO7=poly(ethyleneoxide).    Provided that when the poly(ethyleneoxide)siloxane is (Ia) and R1 is (IIa) or (IIb), then at least one of R2 to R6 is other than alkyl. INDEPENDENT CLAIMS are included for the following:    (1) an electrochemical cell comprising the gel electrolyte (E1) and at least one electrode;    (2) preparing a gel electrolyte involving dissolving a lithium salt and a thermal initiator in a poly(ethylene oxide)siloxane to form a first solution; adding at least two acrylate terminated polyalkylether compounds to the first solution to form a second solution where acrylate terminated polyalkylether compounds comprise an ethylene oxide unit, a propylene oxide unit, or both; casting the second solution onto a substrate; and heating the second solution and substrate until the second solution is solidified; and    (3) assembling an electrochemical cell with a gel electrolyte comprising stacking a porous supporter, a positive electrode laminate, and a negative electrode laminate to form an electrochemical cell; winding or folding the electrochemical cell to prepare a spiral wound cell type or a prismatic cell type; putting the spiral wound or prismatic electrochemical cell in a metal can, a plastic pouch, or a laminated metal foil/plastic pouch; injecting a gel electrolyte solution (E1) into the spiral wound or prismatic electrochemical cell in the metal can, plastic pouch, or laminated metal foil/plastic pouch; and gelling the gel electrolyte solution to form the gel electrolyte.