Synergistic Engineering of Closed Pores Regulation and In Situ Defects Repair in Anthracite-Based Hard Carbon Toward...

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.