Exploring the oxidation chemistry of diethyl carbonate in lithium-ion battery thermal runaway using SVUV-PIMS

Author：Dong, B., Wang, L. Y., Hu, L. H., Fang, J., Wang, Z. D.

Journal：Proceedings of the Combustion Institute

DOI:  10.1016/j.proci.2024.105479

Keywords: Diethyl carbonate, Liquid phase oxidation, Reaction mechanism, Lithium-ion battery, SVUV-PIMS, photoionization cross-sections, low-temperature oxidation, cathode materials, decomposition, pyrolysis, stability, fire, Thermodynamics, Energy & Fuels, Engineering

Abstract: 

With the extensive applications of lithium-ion batteries and widespread concerns about their security, it is necessary to deeply understand the reaction mechanism of thermal runaway process of Li-ion batteries. Oxygen released from cathode and anode materials could react with electrolyte solvents with increased temperatures. However, the chemical mechanism remains elusive due to the complexity of the battery system. In this work, we developed a method to study the oxidation chemistry of electrolyte solvents and oxygen in lithium-ion battery thermal runaway process. The liquid phase oxidation of diethyl carbonate (DEC) with oxygen was studied in a closed autoclave with diverse oxygen concentrations, temperatures and reaction times. The samples were measured by synchrotron vacuum ultraviolet radiation photoionization mass spectrometry (SVUV-PIMS) to quantitatively analyze the oxidation products. It was found that the onset reaction temperature is less than 120 degrees C, which indicates that it maybe occurs in the early stage of Li-ion battery thermal runaway. Besides, the feasible reaction scheme is discussed to rationalize the formation of the primary products.