Conjugation‐Activity Regulated Molecular Templates Enable Microcrystallite‐Refined Hard Carbon for High‐Performance Sodium Storage

ABSTRACT The microcrystallite structure of carbon materials has a significant impact on their electrochemical properties, yet it usually suffers from uncontrollable aromatic ordering and thickening during carbonization. Here, we develop a conjugation‐activity regulated molecular template strategy to program the microcrystallite evolution of coal‐derived hard carbon toward sodium storage. By modulating conjugation capacity and bond–cleavage thresholds of aromatic N‐heterocycles, we propose a molecular template design principle: strong conjugation creates supplementary microcrystallite growth sites to alter aromatic domain evolution, while molecular activity controls the effective activation range for conjugation‐mediated reconstruction. N‐Phenylcarbazole, which integrates a sufficiently conjugated aromatic core with a locally labile N‐phenyl linkage, realizes this balance by enabling radical‐mediated precursor reconstruction during pre‐oxidation and constrained aromatic‐layer rearrangement during carbonization. The resulting hard carbon exhibits refined and dispersed turbostratic microcrystallites with enlarged interlayer spacing and regulated defects, retaining 250.3 mAh g −1 after 5600 cycles at 500 mA g −1 , corresponding to 83.6% capacity retention. This work establishes an activity‐window‐modulated conjugated‐molecule design principle for programming coal‐derived carbon microcrystallites.