Design and construction of hierarchical sea urchin-like NiCo-LDH@ACF composites for high-performance supercapacitors

Abstract

Activated carbon fiber (ACF) from Chinese fir wood powder by melt-spinning was used to prepare a NiCo-LDH@ACF composite material via a microwave-assisted synthesis method, which contained two-dimensional nanosheets and sea urchin-like microspheres with a core-shell structure. Regulating the proportion of Ni2+ and Co2+ in NiCo-LDH@ACF can significantly change the apparent morphology, hierarchical porosity and active sites, thereby affecting the electrochemical performance. When the molar ratio of Ni2+/Co2+ is 1:1, Ni1Co1-LDH@ACF has the largest specific capacitance of 1453 F/g and a very high rate performance of 78 % at 10 A/g. In addition, asymmetric supercapacitors are assembled using NiCo-LDH@ACF composites as the positive electrode and fir bark-based activated carbons as the negative electrode material. The assembled asymmetric supercapacitor device possesses a high specific capacitance of 147 F/g at 1 A/g, superior energy density of 52.2 Wh/kg at 800 W/kg and an incredible cycle life of 79.8 % after 10,000 cycles. All these results suggest that NiCo-LDH@ACF composites have great potential as electrode materials for energy storage devices that benefit from the synergistic effect of both the NiCo-LDH and carbon materials of the ACFs.