The two-phase battery concept: a new strategy for high performance lithiumpolymer batteries

A new concept is proposed to realize high performance lithium polymer batte ries. The two-phase battery concept is based on the use of two polyethers o f different molecular weight. A low molecular weight polyether is used in t he composite cathode to assure high ionic conductivity while a high molecul ar weight polyether is used in the electrolyte formulation. In this work, a composite cathode based on a solid, low molecular weight poly(ethylenglyco l) dimethyl ether (PEG-DME, M.W. 2000), was coupled with a solid polymer el ectrolyte (SPE) based on poly(ethylenoxide) (PEO, M.W. 4 x 10(6)). The elec trochemical stability window, evaluated by a slow sweep voltammetry, showed that the system has an anodic breakdown voltage higher than 4.0 V versus L i. The feasibility of two-phase batteries was evaluated by cycling tests. T he results indicate that two-phase batteries have enhanced performance with respect to PEO based batteries. (C) 2001 Elsevier Science B.V. All rights reserved.