Boric Acid Tailored Pre‐Oxidation Crosslinking and Suppressed Molecular Rearrangement Toward Pitch‐Derived Carbon Anodes for Sodium‐Ion Batteries

Abstract Pitch‐derived carbon is a promising sodium‐ion battery anode but has inadequate sodium storage capacity due to high graphitization and limited active sites from polycyclic aromatic structure polycondensation/stacking during carbonization. Herein, a strategy of enhancing pre‐oxidation crosslinking and suppressing molecular rearrangement of pitch by employing boric acid to construct a boron and oxygen co‐crosslinking carbon precursor structure, further regulating the carbon texture, is proposed. In situ FTIR and subsequent analyses confirmed that B─C─O bonds suppress molecular rearrangement, leading to the formation of a disordered carbon framework, ultimately resulting in a disordered carbon framework. Meanwhile, the borate species derived from the thermal decomposition of boric acid serve as a dual‐functional template and dopant, facilitating the development of a hierarchical mesoporous carbon architecture alongside the incorporation of diverse boron‐doped carbon configurations during high‐temperature carbonization. By tuning boric acid to pitch ratio and carbonization temperature, the pitch‐derived carbon reaches 317 mAh g −1 reversible capacity dominated by a reversible Na⁺ adsorption/intercalation mechanism, 84% initial coulombic efficiency, and excellent cycling stability with 94.3% retention after 5000 cycles at 1 A g −1 . Separately, the 1.5 Ah Na 4 Fe 3 (PO 4 ) 2 P 2 O 7 ||BHC‐1.5‐800 pouch cell maintains 94% capacity retention after 300 cycles at a 0.5C rate.