Ether-based electrolytes, once dismissed for lithium-ion batteries due to poor anodic stability and incompatibility with graphite anodes, have reemerged as versatile candidates enabling stable cycling of next-generation lithium-ion and lithium-metal batteries, benefiting from the development of highly concentrated electrolytes, localized highly concentrated electrolytes, and weakly solvating electrolytes. In this Review, recent progress in the molecular design of ether-based electrolyte solvents for lithium batteries is summarized. The evolution from conventional electrolytes to the emerging electrolyte concepts is first outlined. The benefits of these electrolyte concepts on electrochemical performance are presented, emphasizing the crucial role of solvation manipulation. Then, the effect of ether molecular structures and functional groups on their solvation ability is systematically discussed. Furthermore, data-driven artificial intelligence approaches, including machine learning and deep learning, for ether-based electrolyte development are highlighted. Finally, challenges and future directions for the rational molecular design of ether-based electrolytes are proposed. © 2026 American Chemical Society