Microwave-Assisted Synthesis of Argyrodite Solid Electrolytes and Their Use in Solid-State Batteries

All solid-state batteries are a promising alternative to conventional liquid-based lithium-ion batteries. To achieve a cycling performance that is competitive with lithium-ion batteries, solid electrolytes are needed that are highly conductive and can be produced with low costs. Conventional syntheses using a resistance furnace are often time- and energy-consuming. To reduce the reaction time and achieve more efficient heating, solid-state reactions can be conducted inside a microwave. Due to the excitation of molecular vibrations, this method allows for a more local and energy-efficient heating of the reaction mixture. This study investigates the solid-state synthesis of two argyrodite solid electrolytes Li6PS5Cl and Li5.5PS4.5Cl1.5 in a microwave. Furthermore, the ionic transport and performance as catholytes in solid-state batteries are tested. With the rapid reaction times, it is shown that highly conducting solid electrolytes can be synthesized in less than an hour with cycling performances comparable to solid electrolytes synthesized from conventional solid-state reactions.