Graphitic Lattice‐Induced Microcrystalline Engineering of Two‐Dimensional Coal‐Based Hard Carbon Materials for High‐Performance Sodium Storage

ABSTRACT Coal has emerged as a promising precursor of hard carbon (HC) anode for sodium‐ion batteries due to its high carbon content and abundance of aromatic structures. However, the cross‐linked and rigid macromolecular networks in coal limit the rearrangement of decomposed carbon atoms and atomic fragments during pyrolysis. This impedes precise control of carbon microcrystalline structures in coal‐based HC, posing a huge challenge to the simultaneous improvement of reversible capacity and initial Coulombic efficiency (ICE). Herein, a bottom‐up strategy is proposed to fabricate a 2D coal‐based HC with long‐range, highly oriented pseudo‐graphitic domains (∼5.12 nm) and suitable interlayer spacing (d 002 >0.37 nm) through molecular tailoring, covalent assembly, and microcrystalline engineering. The real‐time structural evolution of carbon microcrystalline induced by graphitic lattice plates, including nucleation energy barrier, formation rate, and orientation degree, is elucidated via the in situ heating transmission electron microscopy and molecular dynamics simulations. As a result, the obtained HC anodes achieve an exceptional ICE exceeding 92.0 % (up to 97.6 %) along with a high reversible capacity of 420.4 (329.0) mAh g −1 . This work provides molecular‐level insights into carbon microcrystalline engineering of coal‐based HC materials as anodes for high‐performance sodium storage.