Efficient dual conductive network based on layered double hydroxide nanospheres and nanosheets anchored in N-carbon nanofibers for asymmetric supercapacitors

A green electrode material with dual conductive networks via electrospinning with carbonization and co-precipitation method is constructed. Nitrogen-based carbon nanofiber network (CCP-N) is used as the inner-conductive, electrochemical-active substrate and flexible skeleton. The Co Ni layered double hydroxide (Co Ni LDH) nanosheets and flower-like nanospheres, which randomly and closely covering the surface of CCP-N, respectively, just as the fungus grow on trunks in nature, is regarded as outer-conductive and active substance collector in order to provide abundant active centers, sufficient reaction interface to advance fast electrolyte ions diffusion and electrons transport. Furthermore, the growth process of Co Ni LDH on CCP-N is observed by controlling growth time and the Co/Ni ratio of the precursor solution. It is found that the optimal Co/Ni ratio was 2:1, while that optimal growth time is 12 h. The specific capacitance of Co Ni LDH@CCP-N electrode reaches 1319.4 F g^-1 at 1 A g^-1. The assembled asymmetric supercapacitor device (CCP-N @ Co Ni LDH//CCP-N) possesses a high energy density of 48.1 W h kg^-1 at power density of 576.8 W kg^-1, excellent cycling stability of 82.2% retention after 10,000 cycles. The results clearly indicate the Co Ni LDH@CCP-N materials have enormously potential in energy storage. This work puts forward a novel strategy for the design and fabrication of green and advanced supercapacitors materials with high power density and energy density.