Quasi-solid-state composite polymer electrolyte with NASICON-type nanofillers for high performance lithium-oxygen batteries

This study designs a quasi-solid-state composite polymer electrolyte (QSCPE) to improve the performance of LiO2 batteries by integrating a composite solid framework and liquid electrolyte. The solid framework, containing poly(vinylidene difluoride-co-hexafluoropropylene) (PVDF-HFP) and sodium superionic conductor (NASICON)-type lithium aluminum germanium phosphate (LAGP) filler, is prepared using a conventional solution casting method. The framework is then activated using a liquid electrolyte to fabricate the QSCPE. The optimized electrolyte exhibits a high ionic conductivity and wide electrochemical stability. The Li/QSCPE/Li symmetric cell shows an overpotential of below 100 mV and a cycle life of >250 cycles at 1 mA cm−2 at a capacity of 2 mA h cm−2, ensuring electrochemical stability. The LiO2 cell fabricated using the optimized electrolyte exhibits significantly improved cyclability with a cycle life of 152. The QSCPE effectively prevents contamination of Li and suppresses the growth of Li dendrites. These results suggest that the LAGP nanofillers-containing QSCPE is a promising approach for further improving the performance of LiO2 batteries.