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

Abstract 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.