N-doped wood carbon electrodes with ultra-high mass loading of nickel cobalt layered hydroxides for high-performance asymmetric supercapacitors

The exceptional electrical conductivity, lightweight nature, and mechanical properties of wood-derived materials render them highly promising for self-supporting supercapacitor electrodes. However, the underutilization of tracheid space in wood suggests that its inherent structural advantages have not been fully harnessed. Herein, the electrodeposition of nickel–cobalt layered double hydroxide (NiCo-LDH) nanosheets onto nitrogen-doped carbonized wood (NCW) is employed to tackle the challenge. The increased thickness of vertically grown NiCo-LDH nanosheets on the tracheid inner wall significantly enhances tracheid cavity utilization. Consequently, the optimal composite electrode demonstrates an outstanding mass loading of 71.7 mg cm −2 and achieves a capacitance of 65.38F cm −2 at 10 mA cm −2 . Furthermore, the assembled asymmetric supercapacitor impressive cycle stability, maintaining 81.75 % of its original capacitance after 10,000 cycles, and achieves a significant energy density of 1.92 mWh cm −2 at 2.92 mW cm −2 . This study presents a convenient and efficient methodology for design of wood-derived carbon electrodes and high-performance supercapacitors with ultra-high mass loading.