In Situ Construction of Lithium Silicide Host with Unhindered Lithium Spread for Dendrite‐Free Lithium Metal Anode

Performance degradation and safety issue caused by Li dendrite growth and huge volume variation hinder the practical application of Li metal anode in high‐energy‐density lithium batteries. Li diffusion barrier of the host is a key parameter that determines the dendrite growth. Herein, a stable Li21Si5 alloy host with very low Li diffusion barriers is designed and prepared by an in situ metallurgical method using low‐cost micron silicon precursor. The low diffusion barrier of Li21Si5 host enables a dendrite‐free Li deposition behavior. It is revealed that the in‐situ formed porous Li21Si5 host not only has high Li affinity, but also suppresses volume variation of the electrode effectively and thus keeps superior structural stability during Li stripping and plating processes. As a result, this new Li metal anode with Li21Si5 host exhibits promising cycle stability and rate capability with low polarization in both symmetric and full cells. This study opens new opportunities for using alloy‐based materials as the hosts for Li composite anodes. An in situ formed Li21Si5 alloy host prepared via a metallurgical method using a low‐cost micron silicon precursor possesses very low Li diffusion barriers. The resulted Li@Li21Si5 electrode demonstrates a dendrite‐free Li deposition behavior, ensuring promising electrochemical performance.