A General Deep Eutectic Solvent-Mediated Scalable Preparation of Halide Solid-State Electrolytes for All-Solid-State Batteries

In the pursuit of high-energy-density all-solid-state lithium batteries, halide solid-state electrolytes (HSSEs) have attracted increasing interest due to their high ionic conductivity and superior high-voltage stability. Developing cost-effective and scalable preparation methods is essential for their practical deployment, yet the current mainstream solid-state preparation routes either require stringent environmental control with prohibitive costs or suffer from low efficiency. Herein, we report a universal deep eutectic solvent (DES)-mediated wet-chemical method that enables the efficient and scalable preparation of HSSEs. Taking Li₃YCl₆ as a typical HSSE, we revealed the competitive coordination and hydrogen-bond formation mechanisms through combined modeling and experiments. This method shows low cost, and good scalability for various HSSEs, and the resultant HSSEs show a similar conductivity (>0.30 mS cm^-1) as that prepared by the solid-state mechanical method. Notably, the humidity-degraded HSSEs can also be readily regenerated by this method. The all-solid-state lithium batteries assembled with the resultant Li₃YCl₆ deliver impressive performance, achieving a high initial Coulombic efficiency of 98.6% with a LiCoO₂ cathode and a remarkable discharge capacity of 195.9 mAh g^-1 with a single-crystal LiNi_0.8Co_0.1Mn_0.1O₂ cathode. This work establishes a new paradigm for the sustainable and scalable manufacturing of HSSEs for next-generation all-solid-state batteries.