Mastering the solid/liquid equilibrium controlling the stability of novel sulfochloride intercalation materials

Intercalation materials, which allow ions to move in and out of a solid structure, are central to how lithium- and sodium-ion batteries store energy. Advancing this chemistry can lead to longer-lasting batteries and more reliable energy storage systems. However, current materials—mostly transition metal oxides and sulfides—can degrade over time as structural changes and reactions with the electrolyte reduce cycle life and performance. This research addresses these limitations by targeting dissolution issues that typically lead to capacity loss and instability during cycling. By developing new materials that are more stable and capable of storing more charge, this work aims to improve both battery lifespan and energy storage capacity. It also supports the use of sodium, a more abundant and cost-effective alternative to lithium, and relies on domestically available materials, helping reduce dependence on critical minerals like lithium. These advances could accelerate the development of sustainable, high-performance battery technologies for future energy systems. The project will provide outreach programs for grades 8–12 to inspire young students and help develop the future STEM workforce essential for ongoing innovation. This project aims to develop novel transition metal sulfochlorides as a new class of intercalation materials for lithium- and sodium-ion batteries. This study hypothesizes that by controlling the formation of transition metal complexes upon dissolution, these limitations from material dissolution can be overcome. The central hypothesis is that substitution of sulfur ligands with chloride will enhance the redox activity of the transition metals while suppressing that of the sulfide ligands, which are known to drive irreversible structural and chemical transformations. To evaluate this hypothesis, the project will address the synthesis and characterization of disordered rock salt sulfochlorides, elucidate the mechanisms governing their solubility in liquid electrolytes, and design optimal electrolytes that perform well under electrochemical operating conditions. To address the tendency of sulfochlorides to dissolve in liquid electrolytes, the chemical landscape governing the dissolution process will be systematically mapped. By varying conducting salts, solvents, and using additives, the ion-ion and solvent-ion interactions responsible for forming soluble adducts will be identified. The detailed characterization of solubility and electrochemical behavior is expected to yield valuable insights into solid-state chemistry. 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.