Construction of FeNiP@CoNi-layered double hydroxide hybrid nanosheets on carbon cloth for high energy asymmetric supercapacitors

Abstract

The rational design and fabrication of flexible pseudocapacitive materials with high energy density and superior cycling stability is desirable to high-performance supercapacitors. A hybrid FeNiP@CoNi-LDH assembled from FeNiP nanosheets and CoNi-LDH nanosheets have been vertically grown on carbon cloth via a sequential hydrothermal reaction, phosphorization treatment and electrodeposition strategy. The as-prepared FeNiP@CoNi-LDH possesses a large surface area, 3D interconnected nanosheet arrays architecture, hierarchical pore structure, and abundant active sites with multiple valances, which provides rapid electron and mass transfer channels within its conducive network. Impressively, as a binder-free electrode for supercapacitors, the FeNiP@CoNi-LDH electrode exhibits a high specific capacitance of 2280.6 F g−1 at a current density of 1 A g−1, outstanding rate capability (1222.2 F g−1 at 20 A g−1), and significantly improved cyclic stability (70.4% capacitance retention after 5000 cycles) compared to pure FeNiP and CoNi-LDH nanosheets, owing to its well-designed nanostructure and synergetic effect between two well-matched pseudocapacitive materials. Besides, an aqueous asymmetric supercapacitor device based on FeNiP@CoNi-LDH and porous carbon delivers a maximum energy density of 87.3 Wh kg−1 at a power density of 408.8 W kg−1, and an excellent cycling stability with a capacitance retention of 73.9% after 20,000 cycles.