Self‐Derived Stress‐Release Phase Enables High‐Performance Self‐Healing Sodium Anodes

Abstract Self‐healing anodes, enabled by liquid metals, stand out among alkali‐ion storage materials due to their spontaneous repairing capability. Nevertheless, a fundamental understanding of the underlying self‐healing mechanism, particularly from the perspective of stress evolution, remains elusive. Herein, a self‐derived stress‐release phase strategy is proposed to elucidate the intrinsic role of liquid gallium (Ga) in achieving self‐healing behavior and high‐performance sodium storage. Specifically, Ga ₂ Se ₃ is selected as a model system, where liquid Ga is self‐derived during the conversion reaction, as confirmed by theoretical calculations and in situ XRD analysis. Abnormal peak shifts of Na ₂ Se observed during cycling are explained by a unit‐cell “breathing” mechanism induced by the liquid Ga, which functions as a stress‐release phase. This process not only heals cracks but also alleviates misfit strains, thereby mitigating structural degradation and enabling long‐term electrochemical stability. As anticipated, Ga ₂ Se ₃ demonstrates superior cycling performance in both half (≈200 mAh g ⁻¹ at 10 A g ⁻¹ ) and full cells (a high‐capacity retention of 91.5% after 150 cycles), highlighting its potential for practical sodium‐ion batteries. The findings provide direct evidence that self‐derived stress‐release phases are key to self‐healing electrodes, offering a new paradigm for designing high‐performance sodium storage systems.