Reconfiguring Terminal Species of Bituminous Coal to Steer Hard Carbon toward High-Capacity and Fast Sodium Storage

Hard carbons derived from coal precursors have shown bright industrial prospect as the low cost anode materials of sodium-ion batteries. However, it is of extreme necessity yet challenge to regulate carbon microstructure toward superior sodium energy storage. In this study, we propose a powerful chemical reconfiguration tactic to steer hard carbons toward high-capacity and fast sodium storage. The functional species on the edge/plane terminals of bituminous coal are finely reconfigured by nitri-oxidation treatment for effectively inhibiting the reordering of carbon layers under high temperature, thereby creating rich ultramicropores/closed pores and expanded interlayer spacing. These structural merits enable the hard carbon to garner an enhanced capacity of 356 mAh g^-1 along with a high initial Coulombic efficiency of 88.1 % and long lifespan. More impressively, the sodium storage kinetics is substantially sped up with a large capacity of 215 mAh g^-1 retained at a high-rate of 2 A g^-1. This work will afford a fresh methodology for precursor modulation to accelerate the real-world practice of hard carbons toward advanced sodium-ion batteries.