Effect of TiO2 nanoparticle additions on the conductivity of network polymer electrolytes for lithium power sources

Abstract

Network copolymer electrolytes were synthesized from polyether (polyester) diacrylates with different structures and chain lengths of polyester diacrylate and polyethylene glycol diacrylate. The optimum matrix for ion transport in the electrolyte was formed from only one type of oligomer. The influence of TiO2 nanopowder additions (∼60 nm) on the conductivity of the copolymer electrolyte was studied. The addition of 10 wt % TiO2 led to an increase in the conductivity by an order of magnitude at 30°C; the effective activation energy decreased by 20%. At elevated temperatures, the mobility of polymer chains increased and the contribution of TiO2 nanoparticles in ion transport was only half of the order of magnitude of the conductivity at 100°C. The increase in the conductivity of the polymer electrolyte after the addition of TiO2 was presumably caused by the formation of a more mobile state of the lithium ion near the nanoparticle surface, as shown by pulsed field gradient (PFG) 7Li NMR.