Molecular Engineering of Electrolyte Solvents for Lithium Metal Batteries: Strategies, Challenges, and Prospects

Lithium metal batteries hold the promise of transformative advancements in energy storage due to their ultrahigh theoretical energy density, yet their commercialization remains hindered by critical challenges, including uncontrolled lithium dendrite growth and unstable solid electrolyte interphases. Central to overcoming these barriers is the electrolyte engineering, particularly the molecular design of the solvents, which critically governs Li + solvation behavior, interfacial stability, and electrochemical performance. Although numerous new solvent molecules have been successively developed, very few can simultaneously achieve high reductive and oxidative stability in order to satisfy the compatibility requirements of lithium metal anodes and the tolerance demands of high‐voltage cathodes, while also ensuring safety and environmental friendliness. This concept aims to systematically summarize the advantages and limitations of mainstream molecular modification strategies developed in recent years, and to offer insights for guiding the future design of advanced solvents. Herein, the dominant strategies, including fluorination, nonfluorinated structural adjustment, and heteroatoms incorporation, are comprehensively examined and future directions are proposed that emphasize on ecofriendly solvent synthesis and multifunctional integration. In this article, inspiration is provided for advancing lithium metal batteries via rational solvent design, tackling challenges in both fundamental science and practical applications.