Unlocking fast-charging capabilities of lithium-ion batteries through liquid electrolyte engineering

Abstract

Global trends toward green energy have empowered the extensive application of high-performance energy storage systems. With the worldwide spread of electric vehicles (EVs), lithium-ion batteries (LIBs) capable of fast-charging have become increasingly important. Nonetheless, state-of-the-art LIBs have failed to satisfy the demands of prospective customers, including rapid charging, extended cycle life, and high energy density. Addressing these challenges through innovations in material science and other advanced battery technologies is essential for meeting the growing demands of prospective customers. Besides the choice of active materials, electrolyte formulation has a significant impact on the fast-charging performance and cycle life of LIBs over a wide range of temperatures. The liquid electrolyte is typically composed of lithium salts to provide an ion source, solvents to carry Li⁺ ions, and functional additives to build a stable solid electrolyte interphase (SEI). To enable the fast movement of Li⁺ ions, the liquid electrolytes should have low viscosity and high ionic conductivity. Meanwhile, SEI layers must be thin, uniform and ionically conductive. Furthermore, the low binding energy of the solvent facilitates desolvation of the solvation sheath, enabling fast Li⁺ ion transport to the anode during fast charging. This review provides the latest insights into rapid Li⁺ ion transport during fast charging, focusing on ensuring a deeper understanding of liquid electrolyte chemistry. The involvement of existing electrolyte mechanisms in materials discovery will develop electrolyte engineering techniques to improve the fast-charging performance of batteries over a wide temperature range and will also facilitate the development of EV-adoptable advanced electrodes.