Biomass absorption of nickel salt derived carbon wrapped NiS/Ni3S4 nanocomposite as efficient electrode for supercapacitors

Abstract

Transition metal sulfides (TMSs) are utilized in supercapacitors as electrode materials for their high theoretical capacity. The fabrication of TMSs/carbon composite for supercapacitors has gained much interest because of its favorable electron conductivity, and mechanical strength. Herein, the biomass absorption method is applied to fabricate NiS/Ni3S4 carbon composite. Carbon-wrapped nickel (Ni@C) is obtained through the carbonization of Ni2+ absorbed biomass. The wrapping structure can prevent nanoparticles from stacking and structure collapse. In the following process, utilizing Na2SO4 as activator and sulfur source, it etches the carbon surface to create multistage pore structure, and meanwhile, the carbon matrix reduced part of SO42- to form S2-/S that can be captured by the available active sites, leading to produce S-S/C-S bond. Subsequently, A-NiS/Ni3S4 @C and NiS/Ni3S4 @C were effectively obtained after sulfuring A-Ni@C and Ni@C in the condition of hydrothermal, respectively. Benefitting from the bonding structure and coating characteristics, A-NiS/Ni3S4 @C presented better ion diffusion behavior and exhibited a specific capacity of 560.6 F g−1 at 1 A g−1, F g−1 higher than that of NiS/Ni3S4 @C. Furthermore, the A-NiS/Ni3S4 @C was also assembled into a hybrid supercapacitor and showed a specific capacity of 118.6 F g−1 at 1 A g−1.