Composite Polymer Electrolytes Based on PVA/PAN for All-Solid-State Lithium Metal Batteries Operated at Room Temperature

In this study, we used a solution-casting technique to prepare all-solid-state composite polymer electrolytes (CPEs) based on poly(vinyl alcohol)/polyacrylonitrile blends, the ceramic filler Li 1 . 4 Al 0 . 4 Ti 1 . 6 (PO 4 ) 3 (LATP, NASICON-type structure), lithium bis(trifluoromethanesulfonyl)imide, and the solid plasticizer succinonitrile (SN) and then investigated their electrochemical stability, ionic transport properties, and interfacial behavior against lithium electrodes . The CPEs prepared with optimal concentrations of LATP (20 wt %) and SN (10 wt %) exhibited a maximum ionic conductivity of 1.13 × 10 –4 S cm –1 at 25 °C, a Li + -ion transference number of 0.507, and an electrochemical stability window of 5.1 V (vs Li/Li + ). This CPE was a free-standing membrane and highly flexible. An all-solid-state Li//LiFePO 4 battery assembled with this CPE displayed excellent cycling stability and rate performance at room temperature. A maximum discharge capacity of 159.6 mA h g –1 was achieved at 0.1C. The full cell achieved a discharge capacity of 119.4 mA h g –1 at 0.5C and a capacity retention of 90.5% after 100 cycles at ambient temperature. Therefore, this as-prepared CPE shows great promise for use in all-solid-state lithium-metal batteries.