The field of the present invention relates to the field of batteries and of polymer electrolytes for batteries and more particularly to the field of lithium batteries.The invention relates to a composition which can be polymerized and/or crosslinked photochemically or under an electron beam for a battery electrolyte comprising: (a) at least one polyorganosiloxane (POS) (A) comprising, per molecule at least 2 siloxyl units carrying radicals comprising an epoxy (Epx) functional group with optionally an ether (Eth) functional group, and at least one of the siloxyl units carries a polyoxyalkylene (Poa) ether radical; (b) at least one electrolyte salt ; and (c) an effective amount of at least one cationic photoinitiator.