Atomic-Template-Assisted Closed-Pore Engineering of Hard Carbons for Kinetically Accelerated and Large-Capacity Sodium Storage

Abstract

Hard carbons are the most promising anodes for sodium-ion batteries (SIBs), yet their practical performance has long been constrained by an inherent compromise between high plateau capacity and rapid reaction kinetics. Herein, we developed an atomic-template-assisted closed-pore engineering strategy to simultaneously enhance sodium storage capacity and accelerate interfacial transport in hard carbons. This approach involved the initial low-temperature construction of nitrogen-doped carbon spacers within nanopores, followed by their controlled removal at higher temperatures, which initiated a cascade of atomic-scale structural rearrangements. The elimination of atomic nitrogen induced in situ chemical etching, generating abundant newly accessible closed pores that markedly increased the low-voltage plateau capacity. Concurrently, nitrogen removal led to the formation of numerous topological defects on the carbon skeleton, which effectively decreased sodium-ion desolvation barriers and catalyzed anion decomposition, promoting the formation of a thin and inorganic-rich solid electrolyte interphase with high ionic conductivity. As a result, the optimized hard carbon anode delivered a remarkable reversible capacity of 327 mAh g⁻¹ along with superior rate capability (156 mAh g⁻¹ at 2 A g⁻¹). This work highlights the essential synergy between internal pore architecture design and active surface engineering for achieving high-energy and high-power density SIBs.