One-step solution process toward formation of Li6PS5Cl argyrodite solid electrolyte for all-solid-state lithium-ion batteries

Solution-processability is one of the merits of sulfide solid electrolytes because it is a facile and scalable process to construct a thin electrolyte coating layer on active material powders to reduce the interfacial resistance. Herein the argyrodite-type Li6PS5X is synthesized by an one-step solution-process method with ethanol, which avoids the multi-step processes and toxic solvent adopted in other reported works, and greatly reduces the processing time. The as-synthesized Li6PS5Cl has room temperature ionic conductivity of 0.21 mS cm−1 and comparable Li-dendrite suppression ability to solid-state-sintered Li6PS5Cl, despite of the unavoidable impurities due to the use of the protic solvent. By coating Li6PS5Cl on LiCoO2 particles with the one-step solution process, the assembled all-solid-state battery exhibits higher capacity and better rate capability than the uncoated baseline battery. The improved electrochemical performance is attributed to a well-maintained interfacial resistance during cycling by the interfacial architecture, though the performance is not good yet and need to be further improved. The one-step solution-process method can be used for coating cathode materials.