NOVELTY - A gel polymer electrolyte precursor for use in a rechargeable cell comprises a bismaleimide monomer or bismaleimide oligomer; an unsaturated compound; a non-aqueous metal salt electrolyte; a non-protonic solvent; and a free radical initiator. The bismaleimide oligomer is prepared by reaction of barbituric acid and bismaleimide.    USE - A gel polymer electrolyte precursor for use in an alkali metal rechargeable cell (claimed).    ADVANTAGE - The gel polymer electrolyte precursor is rapidly formed into a soft gel, improving performance of an alkali metal rechargeable cell by high interface compatibility and high lithium ion conduction between positive and negative electrodes. Leakage of the lithium rechargeable cell utilizing the gel polymer electrolyte is avoided. The gel polymer electrolyte is rapidly crosslinked, leaving electrolyte with a high conductivity of more than 95%.    DETAILED DESCRIPTION - A gel polymer electrolyte precursor for use in a rechargeable cell comprises a bismaleimide monomer or bismaleimide oligomer; an unsaturated compound of formula X-(A-C(=CH2)(R1))n; a non-aqueous metal salt electrolyte; a non-protonic solvent; and a free radical initiator. The bismaleimide oligomer is prepared by reaction of barbituric acid and bismaleimide.    X=O, organic hydrocarbon compounds, organic hydrocarbon oxide compounds, oligomers or polymers;    n=2 or 3;    A=-C(O)-(CH2)m-, -C(O)-O-(CH2)m-, -O-C(O)-(CH2)m-, -C(O)-O-(CH2)m-cyclohexyl-(CH2)m-O-, or X-substituted phenyl compound of formula (i);    m=0-6;    X=H, CN, NO2, or halo; and    R1=H or 1-4C alkyl.    An INDEPENDENT CLAIM is included for an alkali metal rechargeable cell comprising a negative electrode capable of electrochemical insertion and removal from alkali metal; a positive electrode comprising an electrode active substance capable of electrochemical insertion and removal from alkali metal; and a gel polymer electrolyte prepared by heating polymerization/crosslinking of the gel polymer electrolyte precursor.