Mass‐Transfer Engineered Synthesis of Pitch‐Derived Hard Carbons for Enhanced Sodium Storage

Abstract Pitch‐based hard carbons (PHCs) emerge as cost‐efficient anodes for sodium‐ion batteries, yet suffer from inherent trade‐offs among reversible capacity, initial Coulombic efficiency (ICE), and tap density. Herein, this trilemma is resolved via mass‐transfer‐enhanced pre‐oxidation strategy that kinetically tunes oxygen diffusion, enabling simultaneous augmentation of all three parameters. The optimized PHCs demonstrate optimally balanced graphitic domains and disordered architectures, with expanded interlayer spacing (0.388 nm), minimized surface area (3.34 m 2 /g), abundant closed pores (30.29% closed porosity), and a high tap density (0.9 g cm −3 ). Electrochemically, these structural synergies deliver 413.8 mAh g −1 reversible capacity with 90.9% ICE alongside exceptional cycling stability. Full cells constructed with O3‐NaNi 1/3 Fe 1/3 Mn 1/3 O 2 as cathode, demonstrate high energy density (265 Wh kg −1 , based on total active mass). Critically, the kg‐scaled synthesis of PHCs enables industrial validation through an Ah‐scale pouch cell, which retains 87.9% capacity after 500 cycles. This work establishes a scalable route to high‐performance hard carbon for energy‐density, durable sodium storage.