NOVELTY - Manufacturing a polymer electrolyte separator based on a fluoropolymer hybrid organic/inorganic composite, comprises: (ii) reacting at least a fraction of hydroxyl groups of ROH groups with at least a fraction of the metal compound, to obtain a grafted polymer; (iii) hydrolyzing and/or polycondensing the metal compound and/or pendant groups to yield a liquid mixture and incorporating solvent and electrolyte; (iv) casting a film from the obtained liquid mixture; and (v) drying the obtained film.    USE - The process is useful for manufacturing a polymer electrolyte separator, which is useful in a metal-ion secondary battery (all claimed).    ADVANTAGE - The self-standing polymer electrolyte separator can be manufactured with high anodic stability and dielectric constant, improved ionic conductivity or hydrophilicity and electrolyte/liquid plasticizer retention ability.    DETAILED DESCRIPTION - Manufacturing a polymer electrolyte separator based on a fluoropolymer hybrid organic/inorganic composite, comprises: (i) providing a mixture of at least one fluoropolymer comprising recurring units derived from at least one (meth)acrylic (MA) monomer of formula (R1-C(-R2)=C(-R3)-C(=O)-O-ROH) (I), at least one metal compound of formula (X4-m-A-Y1m), at least one electrolyte, and at least one liquid plasticizer; (ii) reacting at least a fraction of hydroxyl groups of the ROH groups with at least a fraction of the metal compound to obtain a grafted polymer comprising pendant groups of formula (-Y1m-1-A-X4-m); (iii) hydrolyzing and/or polycondensing the metal compound and/or pendant groups to yield a liquid mixture comprising fluoropolymer hybrid organic/inorganic composite comprising inorganic domains and incorporating solvent and electrolyte; (iv) casting a film from the obtained liquid mixture; and (v) drying the obtained film.    R1, R2, R3 = H or (1-3C)hydrocarbon;    ROH = 1-5C hydrocarbon moiety comprising at least one OH(polymer (F));    m = 1-4;    A = Si, Ti or Zr;    Y1 = hydrolyzable group; and    X = hydrocarbon, optionally containing one or more functional groups.    An INDEPENDENT CLAIM is included for a metal-ion secondary battery comprising the polymer electrolyte separator.