Sodium (Na) metal has been considered as one of the most promising anodes for achieving next-generation battery systems with high energy density and low cost. Nevertheless, the uncontrolled dendrite growth, infinite volume expansion, and unstable solid/electrolyte interphase severely hinder the practical application of Na metal batteries. Herein, a self-embedded 3D ion/electron-conductive framework consisting of Na₁₅Sn₄ (3D IECF) throughout the Na metal (referred to as NSN-3D IECF) is successfully prepared through the spontaneous alloy reaction between Na and Sn (4Sn + 15Na → Na₁₅Sn₄). The self-embedded 3D IECF, featuring an interconnection network, not only facilitates rapid Na⁺ transfer under high current density, but also offers abundant space for Na⁺ deposition, which alleviates the volume expansion of the electrode during repeated cycling and maintains the interfacial stability of the anode/electrolyte. Meanwhile, the strong affinity between metallic Na and Na₁₅Sn₄ lowers the nucleation energy barrier, achieving uniform and compact Na metal deposition with a dendrite-free morphology. Benefiting from these merits, the NSN-3D IECF-based symmetrical cell exhibits excellent stability at 1 mA cm⁻² and 1 mA h cm⁻² for more than 4000 h and a low polarization voltage (10 mV). More importantly, the full battery paired with the Na₃V₂(PO₄)₂F₃ cathode maintains a reversible capacity of 106.2 mA h g⁻¹ after 650 cycles at 5 C.

中文翻译：

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原位形成的自嵌入离子/电子导电骨架可实现高度稳定的钠金属阳极

钠（Na）金属被认为是实现高能量密度和低成本的下一代电池系统最有前途的阳极之一。然而，不受控制的枝晶生长、无限的体积膨胀和不稳定的固体/电解质界面严重阻碍了钠金属电池的实际应用。在此，通过Na和Sn（4Sn）之间的自发合金反应，成功制备了遍及Na金属的由Na ₁₅ Sn ₄ （3D IECF）组成的自嵌入3D离子/电子导电框架（简称NSN-3D IECF）。 + 15Na → Na ₁₅ Sn ₄ )。自嵌入的3D IECF具有互连网络，不仅有利于高电流密度下的快速Na ⁺转移，而且为Na ⁺沉积提供了充足的空间，减轻了电极在重复循环过程中的体积膨胀，保持了界面稳定性阳极/电解质。同时，金属Na和Na ₁₅ Sn ₄之间的强亲和力降低了成核能垒，实现了均匀致密且无枝晶形貌的Na金属沉积。受益于这些优点，基于IECF的NSN-3D对称电池在1 mA cm ^-2和1 mA h cm ^-2下表现出超过4000小时的优异稳定性和低极化电压（10 mV）。更重要的是，与Na ₃ V ₂ (PO ₄ ) ₂ F ₃正极配对的全电池在5 C下循环650次后仍保持106.2 mA hg ^-1的可逆容量。