Universal Solution Synthesis of Sulfide Solid Electrolytes Using Alkahest for All‐Solid‐State Batteries
Ji Eun Lee, Kern‐Ho Park, Jin Chul Kim, Tae‐Ung Wi, Adams Ha, Yong Bae Song, Dae Yang Oh, Jehoon Woo, Seong Hyeon Kweon, Su Jeong Yeom, Woosuk Cho, Kyung-Su Kim, Hyun‐Wook Lee, Sang Kyu Kwak, Yoon Seok Jung
Abstract
Abstract The wet‐chemical processability of sulfide solid electrolytes (SEs) provides intriguing opportunities for all‐solid‐state batteries. Thus far, sulfide SEs are wet‐prepared either from solid precursors suspended in solvents (suspension synthesis) or from homogeneous solutions using SEs (solution process) with restricted composition spaces. Here, a universal solution synthesis method for preparing sulfide SEs from precursors, not only Li 2 S, P 2 S 5 , LiCl, and Na 2 S, but also metal sulfides (e.g., GeS 2 and SnS 2 ), fully dissolved in an alkahest: a mixture solvent of 1,2‐ethylenediamine (EDA) and 1,2‐ethanedithiol (EDT) (or ethanethiol). Raman spectroscopy and theoretical calculations reveal that the exceptional dissolving power of EDA–EDT toward GeS 2 is due to the nucleophilicity of the thiolate anions that is strong enough to dissociate the GeS bonds. Solution‐synthesized Li 10 GeP 2 S 12 , Li 6 PS 5 Cl, and Na 11 Sn 2 PS 12 exhibit high ionic conductivities (0.74, 1.3, and 0.10 mS cm −1 at 30 °C, respectively), and their application for all‐solid‐state batteries is successfully demonstrated.