MULTI-PHYSICS MODELING OF LI-ION BATTERY MODULE: NON-UNIFORM DEGRADATION AND ITS MITIGATION

Recent regulatory measures designed to reduce emissions, combined with advancements in alternative fuels, are accelerating the shift towards vehicle electrification. While major original equipment manufacturers (OEMs) have already scaled up the deployment of electric vehicles, addressing the engineering challenges of this technology remains crucial. Lithium-ion batteries, though a promising solution for energy storage, present issues such as thermal management, variability in cell capacity, and the risk of thermal runaway. Their complex behavior and sensitivity to temperature during operation require precise modeling and analysis to accurately predict performance. The objective of this thesis is to comprehensively understand involvement of complex electrochemical process inside lithium-ion batteries (LIBs) and development of high fidelity fully coupled thermal electrochemical model to understand effect of temperature non-uniformity on limiting capacity of battery pack.

Thesis explores a comprehensive guideline in developing high fidelity electrochemical model and its coupling with thermal capacity fade model which has SEI formation and Li dendrite growth as a governing capacity fade mechanism. A strategic benchmarking guideline of validating numerical model with set of experimental results are provided. Further this study explores, issue of thermal non-uniformity existence in cylindrical battery module and its direct effect on cell to cell variable non-uniform capacity fading over time under conventional fluid flow thermal design and mitigation strategy to reduce non-uniform capacity loss using reciprocating fluid flow thermal design is demonstrated.