Lithiation-driven cascade dissolution coprecipitation of sulfide superionic conductors

Abstract

We present a Li2S-free and cost-effective wet chemistry method for the preparation of sulfide solid electrolytes (SSEs), which addresses a major challenge in the commercialization of all-solid-state batteries (ASSBs). Our method universally synthesizes various electrolytes, including LixMS4 (M = P, Sb, or Si) and Li6PS5X (X = Cl, Br, or I). It particularly produces Li6PS5Cl of high quality (5.7 mS cm−1 of ionic conductivity at 25 °C) at a material cost of one-tenth of previously reported methods. The synthesis process, featuring a cascade-dissolution-coprecipitation mechanism, is investigated using analytical techniques for soluble intermediates and sediment products. The Li6PS5Cl-based pellet ASSBs with a LiNi0.8Mn0.1Co0.1O2 cathode and a Li-In anode provide high initial capacity (190 mAh g−1 at a 0.1C rate, 55 °C) and hold a capacity retention of > 80 % after 1,000 cycles at a 2.0C rate. Additionally, a 0.7 Ah pouch cell with a silver/carbon anode exhibits a remarkable energy density (352.8 Wh kg−1 at 45 °C). This solvent-based and Li2S-free synthetic process proposes a cost-effective pathway toward sustainable mass production for synthesizing SSEs. © 2024 Elsevier B.V.