Co doping enhances the pseudocapacitive performance of Ni3S4/NiS heterostructures for high-performance asymmetric supercapacitors

The poor conductivity and insufficient number of electroactive sites of nickel sulfide lead to unsatisfactory electrochemical performance. To address this issue, a Co-doped Ni 3 S 4 /NiS heterostructure (NixSy@Co) was prepared by hydrothermal method. Structural and electrochemical characterization indicate that Co doping can modify the surface chemical properties and electronic structure of the NixSy@Co, and enhance the electron transport capability. Density functional theory (DFT) calculations confirm that Co doping can enhance the conductivity of NixSy@Co, and that the adsorption ability of NixSy@Co for the electrolyte was stronger than that of NixSy. The specific capacitance and rate performance of NixSy@Co were superior to those of NixSy. The asymmetric supercapacitor (ASC) constructed with NixSy@Co had an energy density of 48.1 Wh kg −1 . This work provides a good idea for the electronic structure regulation and surface chemical property improvement of transition metal sulfides.