Novel gel polymer electrolytes based on a cellulose ester with PEO side chains

Abstract

A range of gel electrolytes, composed of a hydroxypropylcellulose ester with poly(oxyethylene) side chains, LiCF 3SO 3 and propylene carbonate (PC), or a mixture of propylene carbonate with ethylene carbonate (EC), were prepared and studied. The conductivities of gels containing 10 wt.% LiCF 3SO 3, and having propylene carbonate concentrations varying from 20 to 70 wt.%, exhibit Arrhenius behaviour with activation energies ranging from 16 to 34 kJ mol −1. Room temperature conductivities of the order of 10 −3 S cm −1 are achieved with propylene carbonate contents above 50 wt.%. Gels containing 70 wt.% propylene carbonate, or a mixtures of propylene carbonate and ethylene carbonate, were cross-linked to form elastomeric films exhibiting good mechanical properties and room temperature conductivities of ∼10 −3 S cm −1. The conductivities and mechanical strength of these films increased with increasing ethylene carbonate content. An Arrhenius dependence of log conductivity on (1/ T) is also observed in these films, with activation energies for ion transport around 16 kJ mol −1.