Covalent Tethering of Ion‐Pair Motifs on Waste‐Derived Carbon: A Molecular Approach to Accelerated Interfacial Ion Transfer

ABSTRACT

Sluggish interfacial lithium‐ion (Li ⁺ ) transfer kinetics at the solid–liquid interface remain a fundamental bottleneck for fast‐charging carbon‐based anodes. Herein, we report a molecular engineering strategy to overcome this limitation by constructing covalently tethered ion‐pair motifs on hard carbon derived from industrial toluene diisocyanate residue. Diverging from traditional destructive surface treatments, we implemented a mild, site‐specific nucleophilic substitution (S _N 2) reaction that harnesses the intrinsic lone‐pair electrons of pyridinic nitrogen sites as reactive centers. This non‐destructive interfacial design preserves the structural integrity of the carbon skeleton while triggering a dramatic transition from moderate hydrophobicity to instantaneous dual super‐wettability (0° contact angle) toward both aqueous and organic electrolytes. Multi‐dimensional molecular evidence and Gibbs free energy analysis reveal that the motifs transform the solid‐liquid boundary from a repulsive barrier (+10.51 kcal·mol ⁻¹ ) into an energetic ion trap (−30.84 kcal·mol ⁻¹ ). This asymmetric interface provides a thermodynamic driving force to facilitate desolvation through a selective‐stabilization mechanism, which strongly captures Li ⁺ ions while maintaining low affinity for solvent molecules. Consequently, the modified anode delivers a reversible capacity of ∼1150 mAh·g ⁻¹ . This work not only provides a valorization route for industrial nitrogen‐rich waste but also establishes a generalizable chemoselective strategy to regulate interfacial ion flux through molecular‐level surface engineering.