Poly(vinylidenefluoride)-based porous polymer electrolytes

New multicomponent organic liquid electrolytes, based on mixtures of the co mmercial solution EC-DEC-LiPF6 (A) and tetraglyme/LiPF6 (G4), have been exa mined in terms of thermal and electrochemical behaviour. The composition wi th 40 vol% of G4 seems to be the best compromise among thermal stability, h igh conductivity and wide electrochemical window. Two porous asymmetric pol y(vinylidenefluoride) membranes of porosity higher than 70%, but of differe nt morphology (sponge-like versus finger-like), prepared by the phase inver sion method, are compared in terms of physical-chemical properties, after a ctivation with the pure solution A and the optimal mixture 60:40 v/v A:G4. Conductivities exceeding 2 mS/cm at room temperature are easily obtained, a nd the use of these membranes assures electrochemical stability at least up to 5 V. In spite of the cross-sectional asymmetry of these kinds of membra ne and of the presence of a superficial skin, no relevant differences in th e anodic limit voltages are observed on changing the orientation of the ski n, as demonstrated by linear sweep voltammetry tests on both the surfaces. (C) 2001 Elsevier Science Ltd. All rights reserved.