Endogenous Template‐Directed Topological Engineering of Lignite‐Derived Hard Carbons for Kinetically Accelerated Sodium Storage

Abstract

Abstract Coal is a promising precursor for the preparation of hard carbon, which shows great commercial potential as an anode material for sodium‐ion batteries (SIBs). However, the π–π interactions between planar aromatic molecules and the trend toward graphitization lead to a highly ordered carbon structure with narrow interlayer spacing. In this study, a self‐templating strategy is proposed to regulate the closed‐pore structures of coal‐based hard carbon at the molecular level, and finally improve the plateau capacity. The ‐OH is beneficial for the formation of closed‐pore structure during carbonization by chelation with metal ions, and C═O can help to prevent graphitization, increase the interlayer spacing and form hybrid organic–inorganic SEI through surface functional remodeling with salt in ether‐based electrolytes. The coal‐based hard carbon displays good cycling stability, exhibiting a high reversible capacity (350 mAh g −1 ) at 50 mA g −1 and capacity retention of up to 88% after 8000 cycles at 5 A g −1 . Moreover, the full battery assembled with NVP demonstrates a stable cycling performance. This work provides new insights into the construction of closed pores and the role of carbonyl groups in hard carbons for enhancing sodium storage performance.