Insights into dendrite suppression by alloys and the fabrication of a flexible alloy-polymer protected lithium metal anode

Dendrite growth and unstable surface properties are main challenges for the practical use of lithium metal anode. The promise of Li-rich alloy protection layers on lithium stems from their lower predilection for dendrite growth, however, information from a thermodynamic point of view that invoke the specific properties of the alloy is scarce. Besides, the alloy layers require further engineering to satisfy the volume change of Li during plating/stripping. Herein, we correlated the non-dendritic behavior and the alloy surface properties by low surface barriers, by considering the dynamic event of the electrodeposition when Li atoms encountering the alloy surface. A flexible protective layer containing the Li-rich alloy and polymer was designed on lithium metal, in which the alloy component is responsible for regulating the non-dendrite electrodeposition while the polymer is beneficial for the flexibility. The protected lithium anode remained dendrite‐free for over 3400 h (1700 cycles) at 1 mA cm−2 in Li||Li symmetric cells and exhibited outstanding stability towards the electrolyte.