Construction of hierarchical nickel cobalt sulfide@manganese oxide nanoarrays@nanosheets core-shell electrodes for high-performance electrochemical asymmetric supercapacitor

Core-shell nanostructured three-dimensional binderless electrode porosity makes them ideal candidates for electrochemical energy storage applications. This article proposes NiCo₂S₄@MnO_x electrodes fabricated using a facile hydrothermal approach and subsequently annealed at 120°C for 12 hours. The resultant nanoarrays@nanosheets structure allows rapid ion and electron transport. Coating with pseudocapacitive MnO_x on NiCo₂S₄ nanoarrays improves overall capacitance, and the amorphous MnO_x nanosheets promote electrode cycling stability. The proposed NiCo₂S₄@MnO_x electrode achieved excellent specific capacitance of 1640 F·g⁻¹ at 5 mA·cm⁻² and cyclic stability ≈ 90%; and the subsequently fabricated asymmetric electrochemical supercapacitor achieved specific capacitance ~96.91 F·g⁻¹, and specific energy (SE) 26.38 Wh·kg⁻¹ at specific power (SP) 466.66 W·kg⁻¹, with impressive electrochemical stability ≈ 80% over 5000 charge/discharge cycles.