Thermo-Mechanical Modeling of Electrolyte Evaporation Under Compressive Load and Preventive Charging Protocol in Lithium Batteries

For sustainability, a reliable energy storage system is essential, and lithium-ion battery (LIB) is one of the most prominent among the available storage solutions. However, LIB has various safety concerns associated with overheating. In this work, a chemo-mechano-thermal model is developed to simulate conditions of electrolyte evaporation and thermal runaway in LIB under fast charging (1–7 C) and compressive load (0–100 MPa) conditions. A separator pore-closure model is utilized to simulate porosity changes under compressive load. An electrolyte evaporation model is developed and coupled with the thermal model to predict concentration variations of LiPF6 in EC:DMC (1:1) during overheating. The electrolyte electrical conductivity is modelled, depending on electrolyte concentration, solvent evaporation and separator porosity. A parametric study is performed constituting of five different cathode materials: LCO, NMC333, NMC532, NMC622, NMC811, with graphite (C) as the anode. Contour maps are presented to parametrically study the maximum cell temperature, electrolyte conductivity, and heat generation, for different compressive loads, charging rates and convective coefficients. To mitigate overheating, two charging protocols, i.e., pulse and step charging, are developed to optimize the maximum cell temperature and charging time.