Composite polymer electrolytes prepared by in situ copolymerization of poly(methyl methacrylate-acrylonitrile) on the surface of poly(methyl methacrylate)-coated nano-TiO₂

Composite polymer electrolytes (CPE) for lithium ion batteries are reported. Initially, nano-TiO₂ was modified by coating with a layer of poly(methyl methacrylate) (PMMA) by emulsion polymerization. CPE with this modified nano-TiO₂ were then prepared by the in situ copolymerization of poly(methyl methacrylate-acrylonitrile) (P(MMA-AN)). Morphology, thermal, electrochemical, and spectroscopic measurements were used to characterize the electrolytes. The PMMA-coated nano-TiO₂ was well dispersed in the polymer matrix due to the PMMA coating layer making the nanoparticles hydrophobic to effectively avoid the aggregation of the nanoparticles. The homogeneous CPEs of this PMMA-coated nano-TiO₂ have better thermal tolerance, higher ionic conductivity, and wider electrochemical stability, thus providing a practical route to improved polymer electrolytes.