The Synthesis and Optimization of Sulfide and Halide Solid Electrolytes for All Solid-State Batteries

Countries and organizations around the world have established ambitious targets to transition away from fossil fuel-based energy sources and devices. The transition is focused on cleaning up power generation by converting coal, natural gas, and oil-based power generation to renewables and nuclear energy. Decarbonizing other sectors of energy use, transportation for example, will require broader electrification. To drive this move away from fossil fuel powered transportation will require portable energy storage devices. Conventional lithium-ion batteries are a popular candidate to lead this shift. However, these batteries often rely on flammable liquid electrolytes and carbon anodes that suffer from low energy density and safety risks. All-solid-state lithium batteries in which liquid electrolytes and graphite anodes are placed with solid electrolytes and lithium metal anodes, have emerged as a potential candidate that can meet these requirements of improved safety and energy density. The key to enabling these new chemistries is the development of solid electrolytes with high ionic conductivities, electrochemical and thermal stability, low cost, and ease of processibility for scale up. Although research in solid electrolytes has grown rapidly over the last two decades the impact of synthesis and processing routes on different classes of materials is poorly understood. Developing a deep and thorough understanding of these impacts is crucial to evaluating and enabling the scalability of these materials for incorporation into batteries for electric vehicle applications. This dissertation presents an investigation of the impacts of synthetic and processing conditions on material properties for halide and sulfide lithium solid electrolytes and the impact of these properties on ASSB performance.