Multielectron Redox in Lithium-Rich, Industrial-Element Sulfides for High Energy Density Lithium-Ion Battery Cathodes

This thesis develops a thermodynamic and electronic framework for lithium-ion battery cathodes and applies it to a new class of high-capacity sulfides composed exclusively of industrially abundant elements. It introduces lithium-rich cathodes composed of aluminum, iron, and sulfur that leverage reversible multielectron anion redox, in which the formation and cleavage of sulfur-sulfur bonds enable especially high extents of charge storage. A core design framework is established linking delithiated-phase stability to accessible electrochemical redox capacity. The chemical space is expanded with copper-substituted phases, in which unique copper-sulfur electronic interactions delocalize charge compensation beyond sulfur-sulfur bonds, thereby improving the reversibility of anion redox. These materials achieve high energy densities using only industrial elements, offering a promising foundation for next-generation lithium-ion cathodes that address both performance and raw materials constraints. Thus, this thesis advances the long-term goal of building more sustainable energy systems and expanding access to electricity worldwide.