In Situ Constructed 3D Lithium Anodes for Long‐Cycling All‐Solid‐State Batteries

Constructing a 3D lithium metal anode has been demonstrated to be the most effective strategy to address its dendrite issue in liquid batteries. However, this promising approach has proved challenging to inherit in all‐solid‐state Li metal batteries (ASSLMBs) because of the rigidity of inorganic solid electrolytes (SEs), which constrains interfacial solid–solid ionic contact. Herein, a 3D Li anode is in situ constructed for ASSLMBs by spontaneous chemical reactions between halide SEs and Li metal. The in situ formed Li–Al alloys and well‐maintained sulfide SEs inside the 3D structure serve as continuous electron and Li⁺ transport pathways and facilitate the homogenous distribution of charge carriers. The lithiophilic Li alloy can regulate Li deposition behavior and enable uniform Li nucleation and deposition. Both the Li||Li symmetric and full batteries exhibit good electrochemical performance at high current density. This work provides a universal strategy and new insight perspective to construct 3D Li for high‐performance ASSLMBs.