AbstractThe possibility of using cellulose from kenaf as reinforcing fibres in lithium-conducting composite polymer electrolytes based on 49% poly(methyl methacrylate)-grafted natural rubber and LiCF3SO3 has been explored. Cellulose was extracted from kenaf bast fibres by a two-step chemical treatment, specifically an alkali treatment and a bleaching process. High-performance composite polymer electrolytes were prepared by solution casting with various compositions of cellulose (0-10 wt%). Scanning electron microscopy was used for morphological studies of the kenaf fibres at each stage of treatment. The morphology of the electrolytes showed a good dispersion of the cellulose fibres. Infrared spectroscopy showed significant interactions between Li+ ions from the salt and the C=O and C-O-C groups of methyl methacrylate. X-ray diffraction analysis showed that the crystallinity of the polymer host increased upon addition of cellulose and decreased upon addition of salt. Composite electrolytes with 4 wt% cellulose exhibited the best mechanical performance with 10.9 MPa and 995 MPa for tensile strength and Young’s modulus, respectively. The electrolyte films were analyzed by electrochemical impedance spectroscopy and the optimum value of ionic conductivity of SPE with cellulose was 5.3×10-7 Scm-1. The addition of cellulose involved a weak decrease of the conductivity, which might be due to interactions between cellulose, polymer, and LiCF3SO3. The incorporation of cellulose fibres in polymer electrolytes provides a high reinforcing effect at an acceptable level of ionic conductivity.