The influence of ZnO-modified biomass carbon doping and supporting layered double hydroxides on electrochemical performance

Supercapacitors are highly advantageous power-type energy storage devices. With the continuous development of wearable electronic devices, there is an urgent need to manufacture supercapacitor electrodes with high energy density, flexibility and light weight through simple technologies. In this study, N-doped carbon nanofibers (NCNF) served as a self-supporting substrate. Flexible electrodes were fabricated by coating a mixture of ZnO-modified biochar spheres (BC@ZO) and NiCo-Layered Double Hydroxide (NiCo-LDH) on the NCNF film (NCNF/BC@ZO/NiCo-LDH). The specific capacitance of the electrode reached 697 F g⁻¹ and retained 80.7 % of its initial value after 10,000 charge-discharge cycles. Meanwhile, the specific capacitance of NCNF was 224 F g⁻¹. By combining NCNF/BC@ZO/NiCo-LDH and NCNF, a flexible asymmetric supercapacitor was constructed. The supercapacitor exhibited an specific capacitance of the supercapacitor reached 67 F g⁻¹ and retained 80 % of its capacitance after 8000 cycles. After calculation, the energy density reaches 21 Wh kg⁻¹ at a power density of 757.1 W kg⁻¹. The addition of ZnO-modified biomass carbon has solved the problems of easy agglomeration and poor electrical conductivity of LDH, opening up a new path for the research and development of high-performance supercapacitor electrodes, but also has important practical application value due to its simple preparation method and the easy accessibility of raw materials.