Metal-organic framework derived carbon-coated spherical bimetallic nickel-cobalt sulfide nanoparticles for hybrid supercapacitors

Metal organic frameworks (MOFs) are an ideal platform to construct electroactive materials for electrochemical energy storage due to their unique structure and excellent porosity. However, it is still a challenge to make full use of their structural advantages to rationally design multi-component electrode materials for high-performance supercapacitors. Herein, carbon-coated spherical sulfide nanoparticles are reported by simultaneous carbonization and sulfurization using bimetal/monometal-based MOFs as the precursors. The NiCo₂S₄@C and NiS@C composite nanoparticles have excellent electronic conductivity, large porosity and high electrochemical reaction activity. In particular, the bimetallic NiCo₂S₄@C-based electrode exhibits a high specific capacity of 948.9 C g⁻¹ at 1 A g⁻¹. Furthermore, a hybrid supercapacitor assembled with NiCo₂S₄@C as the positive electrode and activated carbon as the negative electrode achieves a high energy density of 43.8 Wh kg⁻¹ with power density at 799.1 W kg⁻¹, and a capacitance retention rate of 81.9% after being subjected to 5000 cycles of charge and discharge. The results suggests using MOFs as precursors is a feasible strategy to synthesize advanced sulfide-based multi-component materials for electrochemical energy storage.