Dual support ensuring high-energy supercapacitors via high-performance NiCo2S4@Fe2O3 anode and working potential enlarged MnO2 cathode

Development of high-energy and high-power asymmetric supercapacitors (ASCs) is still a great challenge due to the low specific capacitance of anode materials (carbon materials of about 100–200 F g−1) and limited voltage window (<2 V) in aqueous electrolytes. Herein, we demonstrate the rational design of the hybrid NiCo2S4@Fe2O3 nanoneedle array anode with large specific capacitance (342 F g−1 at 5 mV s−1) and MnO2 nanosheet array cathode working in wide potential window (0–1.3 V vs. SCE) for high-energy and high-power ASCs. The unique core-shell hierarchical nanoarchitecture of the hybrid NiCo2S4@Fe2O3 nanoneedle arrays not only provides large surface area for charge storage but also facilitates fast charge transport in the electrode. Moreover, the extended potential window of the MnO2 cathode can effectively increase the device voltage of the as-assembled ASC up to 2.3 V, resulting in significantly increased energy density. The obtained ASC device can deliver a high volumetric energy density of 2.29 mWh cm−3 at 196 mW cm−3 and retain 1.08 mWh cm−3 at 2063 mW cm−3, providing new opportunity for developing high-performance ASCs.