Here we present a high-power all-solid-state supercapacitor based on a novel structure of MnO2@KCu7S4 NWs. The electrodes exhibit excellent electrochemical performance with large specific capacitance of 533 F g−1 and the maximum power density 2.02 kW kg−1, still hold 85% of the capacitance over 6000 cycles. Besides, we also explored the effect of temperature on the capacitance. When compared with capacitance at different temperatures, the specific capacity at 80 °C demonstrates significantly higher. Moreover, two supercapacitors in series can power 41 light-emitting diodes (LEDs) about 4 min. These results suggest that such MnO2@KCu7S4 hybrid composite is promising for next generation high-performance supercapacitors.