Hierarchically porous bowknot-like sodium doped Ni_2P_2O_7-CO_2P_2O_7 with improved supercapacitor performances

摘要

Hierarchically porous bowknot-like sodium doped Ni2P2O7-Co2P2O7 structures have been successfully prepared via a hydrothermal route using sodium tartaric as guiding reagent and subsequent calcination in air. The bowknot-like sodium doped Ni2P2O7-Co2P2O7 possesses porous characteristics building of nanoparticles. These bowknot-like sodium doped Ni2P2O7-Co2P2O7 have surface area of 45.32 m(2) g(-1). The unique porous bowknot-like structures can promote the contacting area between electrode materials and electrolyte, and provide rich channels for ions and electrons transport. Electrochemical measurements reveal that the bowknot-like sodium doped Ni2P2O7-Co2P2O7 exhibit a specific capacity of 295.2 Cg(-1) at 2.0 A g(-1), and excellent cycling performances with 98.8% initial capacity retention after 2000 continuous cycles. Moreover, an asymmetric super-capacitor device was assembled by utilizing the sodium doped Ni2P2O7-Co2P2O7 and activated carbon as cathode and anode, respectively. The device delivers a high energy density of 54.1 Wh kg(-1) at a power density of 1700 W kg(-1). Impressively, the energy density can still reach up to 35.7 Wh kg(-1) at 6778.5 W kg(-1). These remarkable electrochemical performances demonstrate that the bowknot-like sodium doped Ni2P2O7-Co2P2O7 are promising electrode material for supercapacitors.