Electronic structure modulation via atomic Ni doping for metallization-driven high-performance CuCo2S4 supercapacitors

The intrinsically low conductivity of CuCo 2 S 4 severely limits its electrochemical performance as an electrode. Herein, we propose an atomic-level doping strategy via a ternary Cu-Co-Ni MOF precursor to precisely incorporate Ni into the CuCo 2 S 4 lattice. First-principle calculations reveal that Ni doping introduces localized electronic states near the Fermi level, effectively narrowing the bandgap and inducing a semiconductor-to-metallic transition. This electronic structure modulation significantly enhances bulk electron mobility and strengthens the adsorption of electrolyte OH - ions. Coupled with the preserved porous carbon framework and multi-metal synergistic interface, the optimized Ni-CuCo 2 S 4 @C electrode achieves a high specific capacitance of 1046 F g -1 at 1 A g -1 . The assembled asymmetric supercapacitor delivers an energy density of 32 Wh kg -1 at 750 W kg -1 , alongside excellent cycling stability. This work elucidates the electronic origin of performance enhancement and provides a doping-guided design principle for high-conductivity metal sulfide electrodes.