Liquid‐Phase Filling Carbon with High‐Performance Sodium Storage for Sodium‐Ion Batteries

Hard carbon (HC) is currently the most widely used anode material for sodium-ion batteries (SIBs), and the synergistic modulation of the layer pore structure is the·key·to enhancing sodium storage performance. Herein, a simple, low-cost, and·easy-to-scale liquid-phase filling method is proposed. By filling the biomass-derived activated carbon with the graphite-like microcrystalline precursor and then carbonizing it at high temperatures, liquid-phase filling carbon (LPFC) is successfully produced. The·liquid-phase filling·treatment can promote the reconstruction of the graphite-like layer structure, and thus significantly improve the sodium storage performance. The HC electrode prepared by this method has an excellent sodium storage capacity of 382.4 mA h g^-1 at 20 mA g^-1 with an initial coulombic efficiency (ICE) of 82.8%. It maintains reversible capacity of 314.7 mAh g^-1 (87.0%) over 200 cycles at a current density of 50 mA g^-1, also with a capacity retention of 75.0% over 1000 cycles at 200 mA g^-1. The liquid-phase·filling strategy is not·only easy·to operate but also highly scalable, which·provides the large-scale preparation of hard carbon materials for high-performance SIBs.