Defect-rich carbon materials with abundant oxygen functional groups at edge/defect sites for rechargeable...

Because of the high theoretical energy density and abundant resources, rechargeable sodium‑chlorine (NaCl₂) batteries have attracted great attention as an emerging alternative and complementary for conventional energy storage systems. However, their practical application faces critical challenges, including complicated multiphase transformation, easy Cl₂ escape, cathode passivation by NaCl, and commonly exhibit sluggish rate performance and poor cycling life. Herein, we demonstrate the application of one defect-rich carbon with abundant oxygen functional groups at edge/defect sites (DC-O) as an efficient cathode for rechargeable NaCl₂ batteries. The defect regions surrounding the porous carbon cavities can locally enrich Na⁺ and predefine spatially distributed nucleation sites for NaCl formation, effectively confining the deposition of NaCl and preventing Cl₂ escape. Furthermore, the polarized oxygen groups anchored on carbon defects are beneficial for the uniform dispersion of NaCl nucleation and inhibit cathode passivation. The DC-O-based battery delivered a high discharge capacity (initial 9290 mAh g^-1, rechargeable 4000 mAh g^-1), excellent rate performance and long cycling life (400 cycles). Even under extreme conditions, such as low temperature (-20 °C), high active material loading, and lean electrolyte amount, the battery still exhibited superior electrochemical performance. This study presents induced confinement engineering to guide novel conversion-type battery design.