Synergistic Engineering of Closed Pores Regulation and In Situ Defects Repair in Anthracite‐Based Hard Carbon Toward Superior Sodium Storage Performance

Anthracite is considered an ideal precursor for hard carbon anodes in sodium-ion batteries (SIBs) due to its high carbon yield and low cost. However, its highly aromatic molecular structure tends to form long-range ordered microcrystalline domains during high-temperature pyrolysis, which is unfavorable for sodium storage. To address this, this study proposes an integrated strategy combining chemical activation and space-confined chemical vapor deposition (SC-CVD). This approach successfully constructs abundant closed pores while achieving in-situ defect repair, effectively suppressing the growth of graphitic microcrystals and enhancing sodium storage performance. The optimized sample, MDMA-2-6, delivers a remarkable reversible capacity of 484 mA h g^-1 at 20 mA g^-1 with enhanced initial coulombic efficiency (ICE) value of 80%, and outstanding cycling stability of 80.63% capacity retention after 2000 cycles. Furthermore, when paired with Na₃V₂(PO₄)₃ (NVP), the constructed full-cell can provide a high energy density of 290.95 W h kg^-1 with an average voltage of 3.366 V. This study proposes an in-depth insight into the synergistic design of closed-pore structure regulation and defect repair, and provides a practical strategy for high-performance sodium-ion battery carbon anodes.