Tuning carbonized wood fiber via sacrificial template-assisted hydrothermal synthesis for high-performance lithium/sodium-ion batteries

Biomass-derived carbons from natural fiber have attracted great attention as promising anode material in lithium/sodium-ion batteries for their sustainability and hollow structure. However, their poor electrochemical stability and slow kinetics restrict their practical application. Herein, we prepare nitrogen-doped carbonized porous wood fiber (N-PCF) through an in-situ sacrificial template-assisted hydrothermal strategy, using graphitic carbon nitride (g-C3N4) as a template as well as a nitrogen source. The hydrothermal process contributes to enhancing the specific surface area of wood fiber and provides favorable conditions for subsequent doping. It was shown that the optimized N-PCF-2 with a 10:2 mass ratio of wood fiber and g-C3N4 template displayed a large specific surface area, suitable doping heteroatom configurations, and an abundant structure defect, providing excellent electrochemical performance. The N-PCF-2 delivered a high specific capacity of 434 mAh g-1 at 200 mA g-1 after 300 cycles in lithium-ion batteries and 266 mAh g-1 at 200 mA g-1 after 300 cycles in sodium-ion batteries. This work demonstrates that the employment of wood fiber-derived carbon as potential anodes of lithium/sodium-ion batteries will significantly impact the field of energy storage.