Molecular-crosslinking chemistry directed pseudo-graphitic modulation in anthracite-based carbon for enhanced <?A3B2 pi6?>sodium storage

Coal-derived carbon, characterized by its abundance and low cost, holds promising potential as an anode candidate for sodium-ion batteries (SIBs). Typically, anthracite, as the highest rank coal with high carbon content has gained significant interests as promising carbon precursors. However, anthracite-based carbon generally shows inferior Na-storage performance due to its highly ordered microcrystalline structure with narrow interlayer spacing. Herein, an innovative molecular-crosslinking strategy was proposed to prevent the microcrystalline arrangement and promote the formation of pseudo-graphitic phases in anthracite-based carbon. The reactive oxygen-containing groups in anthracite introduced by acid treatment can be efficiently cross-linked with sucrose, resulting in hybrid structures with enhanced pseudo-graphitic phase and fewer surface defects upon carbonization. Compared with pristine anthracite-based carbon, which delivers a Na-storage capacity of only 198.4 mAh g−1, the optimized PSAS-60 achieves a significantly improved capacity of 339.5 mAh g−1 and an initial coulombic efficiency of 80.9% along with excellent cycle and rate capability. In-situ FTIR and MS measurements elucidate the underlying molecular-crosslinking process, whereas in-situ Raman and DFT calculations highlight the critical role of pseudo-graphitic phase in facilitating efficient sodium storage. This work offers valuable insights into molecular-level engineering of coal-based carbons, paving the way for their broader application in commercial SIBs.