a li - ion battery cell comprising a polymeric matrix positive electrode layer member , a polymeric matrix negative electrode layer member , and an interposed microporous polyolefin separator layer member is laminated into a unitary , flexible cell structure by means of heat and pressure without necessity for applied interlayer adhesive . a primary plasticizer for the electrode member matrix polymer is included in the electrode layer compositions . during the lamination operation , which may be carried out at a moderate - temperature that does not compromise the thermal shutdown capability of the microporous separator , the plasticizer softens the polymer into a thermoplastic adhesive which forms an effective bond to the untreated polyolefin surface in the region of the electrode / separator interface . the plasticizer dissipates from the composition along with residual lamination heat or may be extracted with solvent or supercritical fluid , thereby enabling the electrode polymer alone to form a strong , permanent bond to the polyolefin separator member .