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.