Oxidation Anchoring Cross-Linking Strategy Synthesis of Semicoke-Based Hard Carbon for Low-Cost and High-Performance Sodium-Ion Batteries

Semicoke is extensively utilized in the production of carbon-based materials due to its advantages of high carbon yield and low cost. However, as a thermoplastic precursor, it tends to undergo melting and reorganization during thermal decomposition, resulting in the formation of a well-structured graphite lattice, which limits its application in sodium storage. Herein, we introduce an oxidation anchoring cross-linking strategy to synthesize semicoke-based hard carbon (SBHC). This approach effectively incorporates C–O–C and −C(O)–O– functional groups into the semicoke molecules. The introduced oxygen functional groups (OFGs) will enlarge the interlayer spacing and form a more nanoporous structure in the bulk of hard carbon. The optimized SBHC demonstrates a significantly enhanced reversible capacity of 280.84 mAh g^–1, which significantly surpasses the capacity of the raw semicoke-derived hard carbon (134.53 mAh g^–1), with the plateau capacity increase of 2.6 times. This study presents a viable strategy for producing cost-effective, high-performance hard carbon materials for sodium-ion batteries.