Targeting superfast sodium energy of coal-based hard carbon by precise regulation of pseudographitic structure

Coal-based hard carbons (HCs) have garnered a wealth of academic and industrial activities as the cost-effective and promising anode materials for sodium-ion batteries. However, the pyrolysis of coal precursors suffer serious carbon rearrangement that renders minimized active sites and sluggish reaction kinetics. Herein, we demonstrate an effective ribose-mediated strategy of coal precursors to modulate the microstructure of HCs targeting advanced sodium energy. The surface chemistry of bituminous coal is finely modified by ribose with oxygen-containing functional groups, which facilitate the construction of pseudographitic carbon structure having rich closed pores and expanded interlayer spacings. Benefiting from the desirable carbon microstructure, the as-modified HCs harvests an elevated capacity of 336 mAh g⁻¹ at 0.02 A g⁻¹ accompanying with a superhigh initial Coulombic efficiency of 90.1 %. More remarkably, the reaction kinetics and stability is greatly reinforced to enable outstanding rate capability of 225 mAh g⁻¹ at 2 A g⁻¹ and a prominent capacity retention of 96 % after 6000 cycles. In-depth understanding of kinetic characteristics and sodium storage mechanism of HCs are systematically unveiled. The present study underscores the significance of precursor modification for structurally navigating the coal-based HCs toward scale-up applications in high-performance sodium-ion batteries.