Tungsten Carbide-Mediated Interfacial Kinetics of Bamboo Hard Carbon for Fast Sodium Storage

Sodium-ion batteries (SIBs) are promising for large-scale energy storage due to their cost advantages and compatibility with existing lithium-ion battery manufacturing processes. Biomass-derived hard carbon (HC) is a commercially viable anode material but suffers from inherent drawbacks, including sluggish ion diffusion kinetics, low initial Coulombic efficiency (ICE), and poor low-temperature performance. Herein, tungsten carbide (WC)-doped bamboo-derived HC (HB-W) is fabricated via hydrothermal adsorption of phosphotungstic acid followed by high-temperature carbonization. In situ WC optimizes the electrode/electrolyte interface and induces local carbon lattice distortion to accelerate Na⁺ diffusion, while constructing conductive networks and generating local electric fields for synergistic enhancement of ion transport kinetics and structural integrity. As a result, HB-W exhibits outstanding electrochemical performance: an ICE of 93.6%, a reversible capacity of 391.9 mAh g^-1 at 60 mA g^-1, 229.5 mAh g^-1 at 15C, and 96.2% capacity retention after 1000 cycles at -20 °C/1C. This work provides a feasible strategy for boosting the comprehensive performance of biomass-derived HC, advancing its industrial application in high-rate and low-temperature SIBs.