Metal-doped Co₉S₈/MXene nanocomposites for high-performance electrochemical capacitor electrode materials

In recent years, cobalt sulfide has become a potential electrode material due to its considerable theoretical capacitance and high conductivity. However, its agglomerate susceptibility and structural instability during the charging/discharging process have impeded its widespread application. Herein, we synthesize Co₉S₈/MXene nanohybrids using a straightforward one-step solvothermal method, employing MXene nanosheets as a conducting substrate. The strong interfacial interaction of both phases is exploited to efficiently alleviate the above problems. Furthermore, a metal-doped strategy has been adopted to modulate the composition and the structure of the nanocomposites, which could expose more redox active sites and considerably improve the redox kinetics. The obtained Al-Co₉S₈/MXene material has a remarkable electrical conductivity and excellent charge/discharge performance, with the specific capacitance up to 1657.33 F g⁻¹ at 2 A g⁻¹ and a superior rate capability of 75% retention even at 12 A g⁻¹. This strategy not only provides an efficient method for synthetic anode electrode materials but also offers ideas for the development of materials more suitable for industrial applications.