Nickel–Cobalt Bimetallic Phosphide/Hollow-Structured Carbon Nanosphere Composites for Supercapacitor Electrode Materials

Nickel–cobalt bimetallic phosphides possess high theoretical specific capacities, making them excellent materials for supercapacitors. Nevertheless, their limited cycle stability and rate performance hinder their practical application. In order to overcome these challenges, we prepared hollow mesoporous carbon spheres by utilizing phenolic resin (carbon source) and silica (template). Subsequently, by hydrothermal and low-temperature phosphating, NiCoP/HMCS nanocomposite structures were synthesized. The NiCoP/HMCS-2 composite exhibits a specific capacity of 856.06 C g^–1 (at 1 A g^–1), while at 10 A g^–1, it retains 86.45% of its capacity after 5000 cycles. The asymmetric supercapacitor (NiCoP/HMCS-2//AC ASC) assembled with the NiCoP/HMCS-2 electrode as the positive electrode and commercial activated carbon (AC) as the negative electrode exhibits an energy density of 56.35 W h kg^–1 at a power density of 799.92 W kg^–1. The capacity retention rate is 91.2% after 5000 cycles at 10A g^–1. These findings indicate promising potential for NiCoP/HMCS nanocomposites as electrode materials for high-performance supercapacitors.