High-performance aqueous asymmetric supercapacitors with a cathode of MnCo₂O₄ nanowires sandwiched by NiCoMnS₄ nanosheets on Ni foam

In this work, a high-performance cathode comprising hydrothermally grown MnCo2O4 (MCO) nanowires sandwiched by the subsequently electrodeposited Ni-CoMnS4 (NCMS) nanosheets, i.e., MCO@NCMS on Ni foam, is developed. Due to its highly porous and interconnected nanostructure and the synergistic effect of its MCO and NCMS components, an outstanding capacitance of 12,020.8 mF cm(-2) at 1 mA cm(-2) is achieved. In addition, this cathode displays remarkable performance in terms of rate capability and cycle stability. Electrochemical analysis shows that the corresponding aqueous asymmetric supercapacitors have a highly competitive energy density of 0.611 mW h cm(-2) (at 0.800 mW cm(-2)) and robust cycling performance, i.e., similar to 90% retention of the initial capacitance and 100% Coulombic efficiency over 15,000 charge-discharge cycles.