Rapid Mechanochemical Synthesis of Oxyhalide Superionic Conductor: Time-Resolved Structural Evolution.

The design and synthesis of advanced solid electrolytes (SEs) underlie the development of safety and high-energy density all-solid-state batteries (ASSBs). Mechanochemical synthesis stands as the predominant method, yet it faces criticism due to its energy and time-intensive process (typically spanning several hours to days), presenting a significant obstacle to large-scale industrial production. Furthermore, ambiguity surrounding the formation mechanisms of SEs during mechanochemical reactions has limited optimization efforts. In addressing these challenges, evidence is presented that the efficiency of mechanochemical SE synthesis can achieve remarkable heights through process optimization. Specifically, the rapid synthesis of the state-of-the-art Li-Nb-O-Cl superionic conductor in only a few hours is highlighted, while concurrently demonstrating its superior electrochemical performance. Notably, for the first time, a structural evaluation during the mechanochemical reaction by time-resolved in situ synchrotron X-ray scattering experiments unveils a two-stage process. This expeditious mechanochemical synthesis of SEs establishes a foundational step toward the commercialization of ASSBs.