Exploring One-Step Synthesis of Coral-Like NiCo₂S₄ Microsphere Cathodes and Cavity-Like Cu₂O–CuO Nanoparticle Anodes for Asymmetric Supercapacitors

Despite significant advancements in energy storage technologies, the relatively low energy density of supercapacitors remains a critical challenge, limiting their widespread application. In this work, the synthesis of coral-like NiCo2S4 microsphere cathodes on nickel foam and cavity-like Cu2O–CuO nanoparticle anodes on a copper sheet is reported, using one-step hydrothermal and calcination methods, respectively. The optimized NiCo2S4 cathode demonstrates a remarkable capacity of 13.71 F cm–2 at 2 mA cm–2 and maintains 80.8% capacitance retention after 3000 cycles. Meanwhile, the Cu2O–CuO anode demonstrates a high areal specific capacitance of 12.87 F cm–2 at 5 mA cm–2. The assembled NiCo2S4//Cu2O–CuO ASC device achieves an impressive energy density of 0.84 mW h cm–2 at 4.5 mW cm–2 within a 1.8 V potential window, retaining 73.6% of its performance after 10,000 cycles, and successfully powers an LED light for over 120 min. This study presents an efficient, sustainable, one-step approach for the synthesis of NiCo2S4 cathodes and Cu2O–CuO anodes, demonstrating its suitability for cutting-edge energy storage applications.