Ionic liquid-mediated PEO-based solid-state electrolyte membrane modified with Dawson-type polyoxometalates

All-solid-state batteries are promising candidates for the future generation of energy storage materials. An ideal solid-state electrolyte should have the advantages of excellent compatibility with electrodes and decent ionic conductivity. Nevertheless, the inherent low ionic conductivity of polyethylene oxide (PEO)-based electrolytes leads to low capacity, which significantly limits their wide commercial application. In this study, Dawson-type Li₆P₂Mo₁₈O₆₂ (LPM) or Li₆P₂W₁₈O₆₂ (LPW) was selected as lithium salt, combined with ionic liquids (ILs) with ether oxygen chains, and incorporated into a polymer matrix blended with PEO and polyvinylidene fluoride as fillers. A polymer electrolyte film with a smooth surface and uniform filler distribution was prepared using a mechanical co-blending method. The challenge of polyoxometalates as ion-conducting materials is attributed to the strong binding ability of their anion clusters to cations. One prominent benefit of this study is that the dissociation of Li⁺ from LPM or LPW is facilitated by ILs and relies on the ether oxygen chains in ILs for transport, yielding composites with favorable conduction properties. This study demonstrates the vast potential of polyoxometalates in the field of ionic conductivity.