• • Au@HCN yolk-shell structure confines Au nanoparticles in hollow carbon nanospheres, achieving a high Coulombic efficiency of 99.8% over 500 cycles at 1 mA cm−2, addressing dendrite growth and low utilization for practical sodium metal anodes.
• • Alloying-induced amorphization of Au upon sodiation forms a Na-Au amorphous alloy, which enhances sodiophilicity and reduces nucleation overpotential, as evidenced by ex situ XAS and TEM, enabling uniform Na deposition.
• • The void space in the yolk-shell design accommodates volume expansion during alloying, mitigating mechanical stress and ensuring structural stability over 2000 hours of cycling in symmetric cells at 0.5 mA cm−2.
• • Full cells with Na3V2(PO4)3 cathodes deliver a specific capacity of 105 mAh g−1 with 92% capacity retention after 500 cycles, demonstrating practical viability for high-energy sodium metal batteries.