Unlocking Interlayer Confinement Enables All-Slope Hard Carbon with Ultrafast and Highly Reversible Sodium Storage

Addressing the rapid capacity decay of hard carbon anodes under high-current-density conditions remains a critical challenge for sodium-ion batteries. Conventional hard carbon materials suffer from strong interlayer confinement that severely hinders Na+ diffusion, leading to sluggish kinetics and irreversible ion trapping. Although expanding the slope region by introducing more active sites can improve rate performance, it often accelerates excessive SEI formation and reduces the initial Coulombic efficiency (ICE). Herein, we develop an amino N-guided through-pore engineering strategy that effectively mitigates interlayer confinement and enables all-slope-dominated sodium storage with rapid and reversible kinetics. Using a facile gas-phase-assisted pyrolysis process, we achieve simultaneous conversion of irreversible nitrogen configurations into highly reversible pyridinic N sites and in situ construction of vertically aligned through-pores directed by amino species. These amino groups not only passivate reactive edge sites but also facilitate the formation of a thin, gradient SEI enriched with subsurface fluorides, greatly reducing sodium loss and achieving an ultrahigh ICE of 94.9%. The resulting anode exhibits a high reversible capacity of 400.3 mAh g–1, exceptional rate performance (208 mAh g–1 at 50 A g–1), and outstanding cycling stability (92.5% capacity retention after 9000 cycles). This work highlights the crucial role of amino-mediated pore and defect management in synchronizing interfacial stability and ion transport kinetics, providing a viable design strategy for high-power alkali-ion batteries.