CTAB-assisted solvothermal growth of CuCo2S4 on nickel foam for high-performance symmetric supercapacitor

In this work, copper-cobalt sulfide (CuCo2S4) with spinel structure was directly grown on nickel foam by a two-step solvothermal synthesis method using a mixture of water/ethanol as solvent and Na2S.9H2O solution as a sulfur source. The effects of cetyltrimethylammonium bromide (CTAB) contents in the sulfurization step were analyzed by various structural, microstructural, and electrochemical characterization methods. The hierarchical microstructure and high specific capacitance of 4230 F g−1 at a current density of 1 A g−1 were obtained by using 1.5 mmol CTAB during the sulfurization step. Furthermore, the free-binder CuCo2S4 electrode showed a high specific capacitance of 429 F g−1 in the negative potential window of −1.0–0.0 V vs. Ag/AgCl at a current density of 1 A g−1. The symmetric CuCo2S4//CuCo2S4 capacitor stored a high energy density of 63 Wh kg−1 at power density of 2800 W kg−1.