Molecular Weaving of Biomass Precursors: Engineering Hard Carbon With Synergistic sp 2 /sp 3 ‐C and Closed‐Pore Structures for High‐Performance Sodium‐Ion Batteries

ABSTRACT Hard carbon is regarded as one of the most promising anode materials for sodium‐ion batteries (SIBs). However, its practical application is hindered by the incompatibility of the contradiction between rate performance, capacity, and initial coulombic efficiency. Herein, we propose a biomass‐derived molecular weaving carbon strategy that enables precise control over the precursor structure at the molecular scale by controlling the pre‐carbonization temperature. The hydroxyl‐rich starch chains are woven with aromatic lignin skeletons to construct a starch‐lignin‐derived hard carbon (SLHC) interpenetrating polymer network. In the prepared SLHC, the appropriate proportion of sp 2 /sp 3 ‐C enhances both conductivity and additional active sites, whereas abundant andlarge‐sized closed pores provide sufficient space for Na + storage. The synergistic effect enables SLHC to achieve faster Na + diffusion kinetics and higher storage capacity. The SLHC electrode delivers a high reversible capacity of 346.0 mAh g −1 at 30 mA g −1 and retains 190.0 mAh g −1 after 500 cycles at 500 mA g −1 . Additionally, the assembled full‐cell achieves a high energy density of 227.6 Wh kg −1 . Through in situ/ex situ characterization techniques, the intrinsic mechanisms of charge storage and interface dynamics are revealed. This work constructs a molecular engineering strategy for the rational design of high‐performance hard carbon anodes in SIBs.