Ni0.96S/NiS/Ni3S2 coated three-dimensional graphene composite for high energy storage and capacitance retention supercapacitors

Abstract

This research prepares a new Ni0.96S/NiS/Ni3S2 flower-like particles by hydrothermal sulfidation. Fumaric acid is used as a carbon source to synthesize three-dimensional graphene (3DG) to disperse Ni0.96S/NiS/Ni3S2 flower-like particles to obtain Ni0.96S/NiS/Ni3S2/3DG composite material. The Ni0.96S/NiS/Ni3S2/3DG-10 has the best electrochemical performance. The specific capacitance of Ni0.96S/NiS/Ni3S2/3DG-10 is up to 2454.1 F g−1 at current density of 1 A g−1. In addition, at two-electrode applications, the energy density of Ni0.96S/NiS/Ni3S2/3DG-10//AC is as high as 51.7 Wh kg−1. After 8000 cycles at a current density of 10 A g−1, the capacitance attenuation of Ni0.96S/NiS/Ni3S2/3DG-10//AC is only 7.8%. The interaction between different phases can increase the storage space of charge. The special flower-like morphology can provide extra large buffer space for volume changes, thus improving the cyclic stability of the material. Furthermore, Appropriate 3DG quality can effectively improve the dispersion of particles, accelerate electrolyte penetration and ion transport, and give full display to the synergy between pseudo-capacitance and double layer capacitance. Therefore, this research provides a new idea for designing a metal sulfide composite carbon material with a controllable structure and applying it to energy storage equipment.