Ab Initio Molecular Dynamics based Thermal Decomposition Study of Carbonate-based Electrolytes towards Battery Energy Storage

In order to understand the thermal decomposition properties and behavior of carbonate-based electrolytes, the most typical carbonate-based electrolyte, ethylene carbonate, was studied based on AIMD technology. The studied system within 100 EC molecules was run for 10 ps in the constant NVT ensemble in GFN1-xTB Method via CP2K program. The results shows that a total of 20 EC molecules undergo decomposition, leading to the observation of 8 reaction pathways, each resulting in different decomposition products. Also 80 molecules remain undecomposed. CO2 is the main product of decomposition, present in nearly every decomposition pathway. The decomposition products also include ethylene, acetylene, acetaldehyde and so on. The two main decomposition paths are detailed analyzed from a atom-level dynamic analysis. A total of 8 EC molecules decomposed into CO2 and CH3CHO, and 4 EC molecules decomposed into CO2 and CH2OCH2. These are the two most decomposed paths. Time evolution analysis by self-designed Matlab code also shows that EC undergoes sustained thermal decomposition throughout the thermodynamic simulation, leading to the ongoing generation of various products.