Hexanoyl chitosan‐based gel electrolyte for use in lithium‐ion cell

Hexanoyl chitosan that exhibited solubility in tetrahydrofuran (THF) was prepared by acyl modification of chitosan. Films of hexanoyl chitosan‐based polymer electrolyte were prepared by the technique of solution casting. The effect of plasticizers on the transport properties of hexanoyl chitosan‐lithium trifluoromethanesulfonate (LiCF 3 SO 3 ) electrolytes have been investigated. The plasticizers used were ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC) and a mixture of DEC/EC and PC/EC. The conductivity is found to be higher for the dual plasticizer system than the single plasticizer system. The highest room temperature conductivity achieved in the DEC/EC and PC/EC dual plasticizer systems is 4.26 × 10 −5 and 1.09 × 10 −4  S cm −1 , respectively. FT‐IR spectroscopic data has been used to interpret the conductivity trend observed. Transport properties such as charge carrier concentration and diffusion coefficient of cation have been calculated to obtain information that may be used to elucidate the mechanism of conductance. Electrochemical cells based on LiCoO 2 /mesocarbon microbeads (MCMB) couple were assembled using the electrolyte that gave the highest ionic conductivity. The performance of the fabricated cell has also been studied and discussed. Copyright © 2006 John Wiley & Sons, Ltd.