C@KCu7S4 microstructure for solid-state supercapacitors

Abstract

Here we report a high-performance all-solid-state C@KCu₇S₄ hybrid supercapacitor based on carbon (C) particles coated on a KCu₇S₄ electrode. The C@KCu₇S₄ hybrid supercapacitor (2 mg C) shows good electrochemical behavior with a large specific capacitance of 352 F g⁻¹ at a scan rate of 10 mV s⁻¹, the highest energy density of 26.2 W h kg⁻¹ and the highest power density of 994.8 W kg⁻¹, still retaining 86% of the capacitance after 2000 cycles. Moreover, a light-emitting diode (LED) can be lit by three supercapacitors in series for about 3.5 min, indicating the good application prospects of using C@KCu₇S₄ hybrid supercapacitors for energy storage.