This grant supports research that contributes to new knowledge related to the sustainable production of metal sulfides, a class of materials that are needed in many advanced technologies. The high cost of these materials reflects the high temperature, energy intensive processes currently employed for their production and purification. This award supports fundamental research generating the required knowledge for the development of a solution-based process for the manufacturing of these materials that is grounded in the principles of green chemistry and engineering. The critical reagents and solvents employed are recycled in a circular economy. The new process will enable scalable manufacturing of metal sulfide nanocrystals at ambient conditions with the ability to tune their size and shape to optimize performance in subsequent end-use applications. This research focuses on metal sulfides central to next generation battery technologies, addressing the critical storage bottleneck that constrains expanded deployment of renewable electricity required to stem global warming. Therefore, results from this research will benefit the U.S. economy and society. This research involves several disciplines including manufacturing, solution chemistry, separations, and materials science. The multi-disciplinary approach will help broaden participation of underrepresented groups in research and positively impact engineering education through the introduction of entrepreneurship into the curriculum. <br/><br/>The cascaded metathesis process transforms low cost sodium sulfide and metal chlorides into the desired metal sulfide at room temperature with common table salt as the byproduct. However, some scientific barriers are yet to be overcome to realize the full application potential of this approach. Sulfide synthesis is guided by solvent engineering which considers the roles of solvent polarity, donor number and molecular structure on solubility and reactivity. The intrinsic properties of the resulting metal sulfides will be fully characterized, and structure-property-performance relationships will be developed for solid-state electrolytes and advanced cathodes using an array of physical and electrochemical characterization techniques. The solution-based approach will be extended to enable roll-to-roll manufacturing of the sulfide–based alloys and composite materials employed in solid state batteries.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.