An Approach to Preparing Ni–P with Different Phases for Use as Supercapacitor Electrode Materials

Abstract

Herein, we describe a simple two-step approach to prepare nickel phosphide with different phases, such as Ni₂P and Ni₅P₄, to explain the influence of material microstructure and electrical conductivity on electrochemical performance. In this approach, we first prepared a Ni–P precursor through a ball milling process, then controlled the synthesis of either Ni₂P or Ni₅P₄ by the annealing method. The as-prepared Ni₂P and Ni₅P₄ are investigated as supercapacitor electrode materials for potential energy storage applications. The Ni₂P exhibits a high specific capacitance of 843.25 F g⁻¹, whereas the specific capacitance of Ni₅P₄ is 801.5 F g⁻¹. Ni₂P possesses better cycle stability and rate capability than Ni₅P₄. In addition, the Fe₂O₃//Ni₂P supercapacitor displays a high energy density of 35.5 Wh kg⁻¹ at a power density of 400 W kg⁻¹ and long cycle stability with a specific capacitance retention rate of 96 % after 1000 cycles, whereas the Fe₂O₃//Ni₅P₄ supercapacitor exhibits a high energy density of 29.8 Wh kg⁻¹ at a power density of 400 W kg⁻¹ and a specific capacitance retention rate of 86 % after 1000 cycles.