In-Situ Liquid-State NMR Investigations of Lithium-Ion Battery Electrolyte Decomposition

Abstract

Liquid electrolytes play important roles in the lithium-ion batteries (LIBs). In particular, an amount of the electrolyte decomposes to form solid-electrolyte interphase (SEI) that stabilizes the electrolyte-electrode interfaces, while the remining bulk solution transports the cation between the electrodes.[1] In order to develop better electrolytes such as with improved safety and chemical stability, efforts have been devoted to understanding the electrolyte decomposition process, which are mainly performed by studying the solid products that precipitate in the SEI and gases that are released during the decomposition.[2, 3] However, the liquid products or species that are soluble in the electrolyte remain as a mystery. Here, we employ in-situ liquid-state nuclear magnetic resonance (NMR) spectroscopy to study the evolution of LIB electrolyte composition caused by the degradation process. Using the 1D and 2D NMR techniques, we confirm that some degradation products are indeed soluble in the electrolyte. The identification of these compounds gives insights into the degradation processes, which also has implications on how the long-term function of the electrolyte will be affected. Besides the new insights into electrolyte decomposition process in the LIBs, the presented techniques can be extended for studying electrolytes in a broad range of battery systems.REFERENCES[1] W. Wahyudi, X. Guo, V. Ladelta, L. Tsetseris, M.I. Nugraha, Y. Lin, V. Tung, N. Hadjichristidis, Q. Li, K. Xu, J. Ming, T.D. Anthopoulos, Adv. Sci. 2022, 9, 2202405.[2] W. Wahyudi, V. Ladelta, L. Tsetseris, M.M. Alsabban, X. Guo, E. Yengel, H. Faber, B. Adilbekova, A. Seitkhan, A.H. Emwas, M.N. Hedhili, L.J. Li, V. Tung, N. Hadjichristidis, T.D. Anthopoulos, J. Ming, Adv. Funct. Mater. 2021, 31, 2101593.[3] C. Misiewicz, R. Lundström, I. Ahmed, M.J. Lacey, W.R. Brant, E.J. Berg, J. Power Sources 2023, 554, 232318.