Regulation of pseudographitic carbon domain to boost sodium energy storage

Hard carbon anode has shown extraordinary potentials for sodium-ion batteries (SIBs) owing to the cost-effectiveness and advantaged microstructure. Nevertheless, the widespread application of hard carbon is still hindered by the insufficient sodium storage capacity and depressed rate property, which are mainly induced by the undesirable pseudographitic structure. Herein, we develop a molten-salt-mediated strategy to regulate the pseudographitic structure of hard carbon with suitable interlayer spacing and enlarged pseudographitic domain, which is conducive to the intercalation capacity and diffusion kinetics of sodium ions. Impressively, the optimized hard carbon anode delivers a high reversible capacity of 320 mAh·g⁻¹, along with superior rate property (138 mAh·g⁻¹ at 2 A·g⁻¹) and stable cyclability over 1800 cycles. Moreover, the in situ Raman spectroscopic study and full-cell assembly further investigate the sodium storage mechanism and practical implement of obtained hard carbon. This work pioneers a low-cost and effective route to regulate the pseudographitic structure of hard carbon materials for advanced SIBs.