Fabrication of NiHPO3·H2O nanorods as cathode material for aqueous asymmetric supercapacitor

Abstract

Abstract The development of novel pseudocapacitve materials with optimal nanostructures has tremendous potential in enhancing the electrochemical properties of supercapacitors. Herein, NiHPO3·H2O nanorods were prepared via an one-step hydrothermal method. Benefiting from its high electrical conductivity, unique one-dimensional rode-like morphology and hierarichical pore structure, NiHPO3·H2O nanorods favor electron and ion transport and provide abundant electrochemical active sites for redox reactions. When applied as positive electrode for pseudocapacitor, the proposed NiHPO3·H2O electrode shows a high specific capacitance of 1405.6 F g−1 at 1 A g−1, outstanding rate capability (64.2% capacitance retention at 10 A g−1) along with good cycling stability (77.3% capacitance retention after 5000 cycles). Furthermore, the assembled asymmetric supercapacitor using NiHPO3·H2O as a positive electrode and pine pollen-derived hierarchical porous carbon as a negative electrode delivers a high energy density (42.6 Wh kg−1 at a power density of 449.1 W kg−1) and a long cycle life (84.7% retention after 10,000 cycles). These findings provide new opportunities to synthesize novel transition metal phosphites for supercapacitors.