Li N(CF3SO2)2 Kynar Gels at Carbon Negative Electrodes

Electrolyte solutions, comprising of LiN(CF3SO2)(2) dissolved in solvent mixtures of ethylene carbonate (EC) and either dimethyl carbonate (DMC) or ethylmethyl carbonate (EMC), were used to prepare films after gelling with an appropriate quantity of Kynar(TM) polymer. The specific conductivity of each film is comparable with liquid electrolyte solutions at ambient temperatures. Half-cells assembled with each gel film and graphite from different sources are shown to have good cyclability with practical capacities of around 350 mA h g(-1) at C/8. Cells constructed using coke as the active electrode material were also cycled successfully at a high charge/discharge rate of C/4 (1 mA cm(-2)) with practical capacities of greater than 700 mA h g(-1). An EC:ENC:Kynar-based cell was successfully cycled at 0 degrees C using this electrode material. Although an increase in the resistance of the passivating layer was observed at 0 degrees C, the cell sustained a capacity of 230 mA h g(-1) at a rate of C/50. (C) 1999 Elsevier Science S.A. All rights reserved.