Ignition Inhibition of Dialkyl Carbonate Solvents used in Lithium-Ion Batteries via Fluorination

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Lithium-ion batteries play a key role in our daily life and are essential for transforming the mobility sector towards a post-fossil era. The ion transport in such batteries is typically facilitated via electrolytes which require solution in a liquid to maintain charge transfer. In this context, carbonates are widely used solvents for lithium-ion batteries, yet these highly flammable compounds pose a thread during battery operation. Mechanical, electrical, or thermal stress can cause battery fires which are fueled by the carbonate solvents. A promising approach to improve the ignition and fire safety of lithium-ion batteries is the use of fluorinated carbonate solvents. Despite their potential for reducing ignition tendency, the fundamental combustion characteristics of these fluorinated carbonates are not yet thoroughly investigated. In the proposed research, experiments in a shock tube and a rapid compression machine in combination with ab initio calculations will allow developing consistent and validated detailed chemical kinetic models for predicting the combustion behavior of fluorinated dialkyl carbonates. This combustion behavior will be compared to that of the non-fluorinated, i.e. regular, dialkyl carbonate counterparts to gain an in-depth understanding of the effect of fluorination on the combustion chemistry. The proposed theoretical, modeling, and experimental research on regular and fluorinated dimethyl, ethyl methyl, and diethyl carbonate will be the first systematic investigation and will critically add to the solvent design process which is required to prepare current solvent technologies for the increasing demand for safe lithium-ion batteries.