Plasma‐Tailored Vertical Graphene Sheath Boosts Sodium‐Storage Kinetics in Starch‐Derived Hard Carbon Anodes

ABSTRACT Despite its promise as a viable anode material for sodium‐ion batteries (SIBs), hard carbon (HC) remains plagued by the simultaneous realization of high capacity, high initial‐Coulombic‐efficiency (ICE), and superior rate‐capability—a bottleneck rooted in microstructural disorder and deficient electronic transport. Herein, a synergistic dual‐engineering strategy is reported to circumvent this trilemma. Our approach combines ZnAc 2 ‐molecular‐templating during electrospinning with subsequent vertical graphene (VG) growth via plasma‐enhanced chemical vapor deposition (PECVD). The sacrificial template generates a dense network of closed nanopores, dramatically increasing Na + plateau storage, while the conformal VG sheath establishes an uninterrupted conductive highway that shortens electron pathways. This design boosts closed pore volume by 1.75 times and electronic conductivity by 4.19 times. As a result, the VG‐reinforced AC anode achieves an ultrahigh reversible capacity of 440.6 mAh g −1 , ICE of 92.24%, and high‐rate performance (323.6 mAh g −1 at 0.8 A g −1 ). Beyond electrode engineering, the intrinsic flexibility and surface functionality of the electrospun membrane enable a “three‐in‐one” full‐cell architecture, where a single fibrous membrane acts as the anode, separator, and cathode host simultaneously. This integrated device delivers an energy density of 325 Wh kg −1 and a high‐power output of 1794 W kg −1 , underscoring the potential of coupling chemical activation with nanocarbon‐grafting for next‐generation SIBs.