Hierarchical carbon layer coated NiCoP nanoparticles embedded on nitrogen-doped carbon nanotubes for high-performance supercapacitors

Abstract

Transition metal phosphides (TMPs) have been widely recognized as an ideal choice for supercapacitors (SCs) due to exceptional pseudocapacitance performance. Otherwise, reasonable structural design of TMPs can overcome the defects of low rate performance and poor cycle life. Furthermore, the incorporation of carbon materials can enhance electronic conductivity, thereby enabling rapid electron transmission. Herein, we present a novel hierarchical carbon layer coated NiCoP nanoparticles embedded on nitrogen-doped carbon nanotubes (NiCoP/NCNTs), synthesized through a calcination/phosphorization process. By incorporating a carbon layer to anchor nanoscale NiCoP, an increased number of active sites and improved structural stability are achieved. Furthermore, the presence of NCNTs enhances the electronic conductivity. These combined features result in impressive performance, with NiCoP/NCNTs exhibiting an impressive specific capacitance of 1628.4 F/g at 1 A/g, and good rate capability of 78.5 % up to 50 A/g. Moreover, it also exhibits outstanding cycling stability, maintaining a capacitance retention of 71.4% after 10 000 cycles. Moreover, the asymmetric SCs based on NiCoP/NCNTs and AC deliver a high energy density of 45.46 Wh/kg, and exhibit excellent cycling stability of 92.5% after 5000 cycles. These results highlight the potential of NiCoP/NCNTs as a novel battery-type electrode material for energy-storage devices.