Concepedia

Abstract

The dependence on (P(EO) = poly(ethylene oxide), X = or )) cell cycle life and rate capability on polymer electrolyte composition is described. Transition time experiments and mathematical modeling indicate that failure due to salt precipitation occurs at it1/2 = 10.5 to 21.4 mA s0.5/cm2, when high initial concentrations of are used in operating cells. Evidence for large ionic clusters in concentrated solutions is also seen in the Raman spectroscopic data. Salt precipitation is a direct consequence of the concentration gradients that arise during operation, due to the negative cationic transference numbers of the binary salt/polymer electrolyte. By decreasing the initial salt concentration, is increased, cell rate capability is doubled, and the cycle life is enhanced nearly threefold. Similar improvements are obtained when electrolytes are used.