High Capacity and Energy Density of Zn–Ni–Co–P Nanowire Arrays as an Advanced Electrode for Aqueous Asymmetric Supercapacitor

Developing multicomponent transition-metal phosphides has become an efficient way to improve the capacitive performance of single-component transition-metal phosphides. However, reports on quaternary phosphides for supercapacitor applications are still scarce. Here, we report high capacity and energy density of Zn–Ni–Co–P quaternary phosphide nanowire arrays on nickel foam (ZNCP-NF) composed of highly conductive metal-rich phosphides as an advanced binder-free electrode in aqueous asymmetric supercapacitors. In a three-electrode system using the new electrode, a high specific capacity of 1111 C g–1 was obtained at a current density of 10 A g–1. Analysis of this aqueous asymmetric supercapacitor with ZNCP-NF as the positive electrode and commercial activated carbon as the negative electrode reveals a high energy density (37.59 Wh kg–1 at a power density of 856.52 W kg–1) and an outstanding cycling performance (capacity retention of 92.68% after 10 000 cycles at 2 A g–1). Our results open a path for a new design of advanced electrode material for supercapacitors.