Method of making bonded-electrode rechargeable electrochemical cells

Abstract

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.