Sulfide-Fixed Intrinsic Porous NiCoP for Boosting High Capacitance and Long-Term Stability

The electrochemical activity and stability of energy storage devices determine their practical prospects. In this work, we developed a method to form sulfide-fixed intrinsic porous NiCoP by sequential heat treatment, phosphorization, and vulcanization from Ni–Co layered double hydroxides. The intrinsic porosity is different from the pore structure constructed by traditional micronano structure because of the secondary defect structures accompanying the preparation process. The further sulfurization of the phosphide can form sulfides near the intrinsic pores. The sulfides of NiS and Co3S4 are typically enriched around the pores. These sulfides can enhance the electrochemical activity and robustness of the pores. The changes in the electronic structure and atomic packing factor were conducive to enhanced conductivity and structural stability because of the differences in electronegativity and atomic radius based on sulfur and phosphorus atoms. The charge storage mechanism was also evaluated by semiempirical equations to further verify how vulcanization increased the capacitance.