MnO₂-MXene Composite as Electrode for Supercapacitor

A MnO2-MXene composite material is reported, in which MnO2 particles have been grown onto Ti3C2 MXene flakes. Thanks to its interconnected structure, it can not only boost the low electrical conductivity of MnO2, but also suppress the restacking of MXene flakes. As an electrode material in a three-electrode cell, the composite showed greater capacitance and improved stability performance than raw MnO2 in both KOH and Na2SO4 aqueous electrolytes. Equipped with MnO2-MXene composite material as positive and activated carbon as negative, an asymmetric device using Na2SO4 as electrolyte displayed an energy density of 20 Wh kg(-1) at 500 W kg(-1) power density. On the other hand, the device operated in KOH electrolyte showed an energy density of 17 Wh kg(-1) at 400 W kg(-1), and 11 Wh kg(-1) at 8 kW kg(-1).