LiN(CF3SO2)(2) Kynar gels at carbon negative electrodes

Electrolyte solutions, comprising of LiN(CF3SO2)(2) dissolved in solvent mi xtures of ethylene carbonate (EC) and either dimethyl carbonate (DMC) or et hylmethyl carbonate (EMC), were used to prepare films after gelling with an appropriate quantity of Kynar(TM) polymer. The specific conductivity of ea ch film is comparable with liquid electrolyte solutions at ambient temperat ures. Half-cells assembled with each gel film and graphite from different s ources are shown to have good cyclability with practical capacities of arou nd 350 mA h g(-1) at C/8. Cells constructed using coke as the active electr ode 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 pas sivating layer was observed at 0 degrees C, the cell sustained a capacity o f 230 mA h g(-1) at a rate of C/50. (C) 1999 Elsevier Science S.A. All righ ts reserved.