Hierarchically structured transition metal (Cu, Ni) sulfide core-shell electrode for high-performance supercapacitor

The development of transition metal sulfide electrode materials for high-performance electrochemical capacitors is important for future energy storage applications. This paper presents the synthesis of electrodes consisting of dense one-dimensional (1D) copper sulfide (CuxS) nanorod cores with two-dimensional (2D) nickel sulfide (NiSx) nanoflake shells on a copper mesh, designated as 1D/2D-CS electrodes. We employed a rapid two-step synthesis method that combines solution-based sulfurization with cyclic voltammetry electrodeposition. This innovative electrode fabrication approach is faster and more efficient than traditional hydrothermal methods, thereby broadening the potential applicability of high-performance core-shell supercapacitor electrodes. The 1D/2D-CS electrode outperformed the core-only 1D CuxS nanorods (1D-CNR) electrode electrochemically, achieving a 58.73 % increase in the specific capacitance at a current density of 10 mA cm- 2 . Furthermore, the 1D/2D-CS asymmetric supercapacitor (ASC) exhibited a high capacitance retention of 77 % after 4000 cycles at a current density of 20 mA cm- 2 , which is comparable to the 79 % retention observed in the 1D-CNR ASC. The 1D/2DCS//activated carbon ASC achieved an impressive energy density of 0.64 mWh cm- 2 and a power density of 7.5 mW cm- 2 , indicating its potential utility in advanced energy storage applications. This study represents a significant advancement in supercapacitor technology, paving the way for sustainable and efficient energy storage systems.