High-throughput synthesis workflows to develop halide solid electrolytes for Li batteries

Next generation Li-ion batteries (LIBs) must be higher in energy and safer. A potential approach to realizing this goal is by using solid electrolytes (SEs), where safety and energy density are greatly improved compared to LIBs using liquid electrolytes. Among different classes of SEs, halide solid electrolytes are attracting significant research due to high ionic conductivity (>1 mS cm−1), compatibility with high-voltage cathodes and mechanical deformability. However, they are extremely unstable in ambient air, making their study slow with low throughputs given the need for inert atmosphere at each step. Here, we present a methods-focused study that establishes novel high-throughput air-free workflows to prepare samples under argon. We use Li3InCl6 for the proof-of-concept to validate these workflows and obtain phase pure materials with >1 mS cm−1 by both a water-mediated and a ball milling approach. Both synthesis routes allow for 64 samples to be prepared at once. This study thereby establishes combinatorial ball milling for the first time using 3D-printed jars. Electronic conductivity was also measured as part of our high-throughput suite, as well as electrochemical stability window measurements on a down-selection of samples. We therefore establish air-free workflows that enable our typical throughput of about 1500 compositional modifications per year, including mixed anion and cation doping. This new infrastructure can now be used to explore novel compositions.