Pore‐Wall Defect‐Mediated Sodium Cluster Nucleation in Hard Carbons Engineered by Misaligned Stacking of Carbon Dots

ABSTRACT Hard carbons (HCs) are highly promising anodes for sodium‐ion batteries (SIBs). However, the elusive relationship between pore‐wall defects and closed‐pore structures severely impedes their rational design. Herein, a pioneering bottom‐up strategy is demonstrated, employing carbon dots (CDs) as transitional building blocks to construct micropore‐rich HCs with tuned curvature. The diffusion constraints of peripheral aliphatic chains surrounding the CDs induce highly rigid ester cross‐linking, achieving a misaligned stacking design of the precursors to eventually yield a defect‐rich, turbostratic framework with abundant closed pores. Consequently, the optimized anode delivers an exceptional specific capacity of 365.0 mAh g −1 and an initial coulombic efficiency (ICE) of 85.06%. Crucially, a novel “pore‐wall defect‐mediated sodium cluster nucleation” mechanism is unveiled to resolve the asymmetric kinetics, demonstrating that vacancy‐associated sites facilitate local charge transfer while the pore‐walls suppress the formation of charge‐transfer‐impeding SEI, thereby inducing quasi‐metallic sodium clustering. This work bridges the spatiotemporal gaps between defects and closed pores, as well as adsorption and pore‐filling stages, promoting the development of next‐generation advanced HC anodes for SIBs.