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

A range of gel electrolytes, composed of a hydroxypropylcellulose ester with poly(oxyethylene) side chains, LiCF₃SO₃ 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.% LiCF₃SO₃, 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. © 2003 Elsevier Science B.V. All rights reserved.