A Robust Pomegranate‐Like CuSn@N,O‐C Anode for Superior Sodium‐Ion Storage

ABSTRACT Tin (Sn) metal possesses a high theoretical capacity as an anode for sodium‐ion batteries (SIBs), yet its practical use is hindered by poor cycling stability arising from severe mechanical degradation during repeated Na + insertion/extraction. Guided by stress distribution simulations, a pomegranate‐like architecture was identified as an optimal structural configuration, exhibiting ∼29% lower maximum von Mises stress than a conventional porous structure. Inspired by this design, a pomegranate‐structured composite was synthesized, featuring a porous CuSn alloy core encapsulated by a continuous N, O codoped carbon shell (CuSn@NOC). The material was fabricated through hydrothermal synthesis, polydopamine self‐polymerization, and oxygen‐deficient annealing. Benefiting from this hierarchical design, the anode delivers a high reversible capacity of 656.79 mAh g − 1 after 800 cycles at 500 mA g − 1 . A full cell paired with a Na 3 V 2 (PO 4 ) 3 cathode achieves energy densities of 291.7 and 216.2 Wh kg − 1 at power densities of 1100 and 4400 W kg − 1 , respectively. Mechanistic analysis reveals that the porous core effectively dissipates stress, while the N‐doped carbon shell ensures structural integrity and suppresses particle pulverization. The synergistic effect with the electrochemically stable Cu 6 Sn 5 phase confers outstanding mechanical and electrochemical durability, offering a robust strategy for designing long‐life alloy‐based SIB anodes.