High-Energy-Density Asymmetric Supercapacitor Based on a Durable and Stable Manganese Molybdate Nanostructure Electrode for Energy Storage Systems

3D interconnected MnMoO 4 nanosheet arrays with abundant open spaces and ordered arrangements deposited on nickel foam (NF@MnMoO 4 ) are fabricated by a mild one-step hydrothermal method. As an integrated binder-free electrode for supercapacitors, the optimized NF@MnMoO 4 electrode exhibits a super-high specific capacitance of 4609 F g –1 (640 mAh g –1 ) at a current density of 1 A g –1, remarkable rate capability (2800 F g –1 (388.89 mAh g –1 ) even at a current density as high as 20 A g –1 ), and outstanding cycling stability (92.4% of the initial specific capacitance after 20,000 cycles). The fabricated NF@MnMoO 4 //AC asymmetric supercapacitors (ASCs) with excellent cycling performance and high Coulombic efficiency achieve an ultrahigh energy density of 107.38 Wh kg –1 at a power density of 801.34 W kg –1 (72.18 Wh kg –1 at a power density of 3987.85 W kg –1 ). As the practical application, the self-charging power packs of commercial solar cells and NF@MnMoO 4 //AC ASCs are demonstrated to power an LED without extra recharging by other devices, indicating their promising applications in self-power energy-harvesting storage systems.