Proton-Conducting Polyoxometalates as Redox Electrolytes Synergistically Boosting the Performance of Self-Healing Solid-State Supercapacitors with Polyaniline

Energy storage devices with high volumetric and gravimetric capacitance are in urgent demand due to the booming market of portable and wearable electronics.Using redox-active molecules as electrolytes is a strategy to improve the capacitance and energy density of solid-state supercapacitors(SCs).In this study,polyoxometalates(POMs)are applied as proton conductors and redox mediators in polyvinyl alcohol(PVA)electrolytes,which increase the capacitance of obtained SCs with polyaniline(PANI).H_(3)PMo_(12)O_(40)-loaded PANI electrodes provide pseudocapacitance with an eight-electron Faraday reaction in a charge–discharge cycle.This has rarely been reported in SCs before.The largest capacitance of SCs with H_(3)PMo_(12)O_(40)and H_(3)PW_(12)O_(40)as electrolytes is 7.69 F/cm^(2)(3840 F/g)based on a single electrode at 0.5 mA/cm^(2).In addition,POM electrolytes exhibit excellent self-healing ability,which is attributed to the rich hydrogen-bonding network between POMs and PVA.This study demonstrates that the capacitance of solid-state SCs is improved by using molecular redox-active electrolytes and showcases the potential of applying this strategy to other energy storage devices in the future.