Experimental Investigation of Factors Influencing Thermal Runaway in Lithium-Ion Battery Cells

In the fast-paced automotive development environment, experimental testing is often constrained by time and budget limitations. Consequently, tests are frequently conducted to meet regulatory requirements, industry standards, or internal guidelines. This leads to minimalistic testing approaches such as "One Factor at a Time" (OFAT) or "Trial and Error", which fail to capture parameter interactions and system complexities. This study investigates the critical factors influencing the thermal runaway behavior of lithium-ion battery cells under controlled experimental conditions. A statistical full-factorial experimental design was implemented to evaluate the impact of state of charge (SoC), heating trigger power, and cell capacity. The experiments, conducted using an autoclave setup, allowed for precise control of external conditions and detailed measurement of thermal and mechanical responses. The cells investigated are automotive-grade lithium-ion cells from development projects, ensuring relevance for next-generation applications. The statistical full-factorial experimental design in this study emphasizes the need for carefully planned test strategies, particularly for cost- and safety-critical topics. A structured design not only ensures compliance but also facilitates a deeper engineering-scientific understanding of the system. This paper proposes a systematic evaluation methodology using factorial regression and statistical analysis techniques to quantify the influence of parameters and their interactions. The study identifies critical temperatures, gas evolution rates, and energy release mechanisms during thermal runaway. Statistical analysis highlights the dominant roles of SoC and heating power in determining the severity and onset of thermal runaway. The findings underscore the importance of comprehensive testing to improve the safety and design of lithium-ion batteries, particularly for high-energy applications like electric vehicles. This work advances the understanding of thermal instability and provides guidance for mitigating risks through design optimization. Future research will focus on enhancing thermal management strategies to reduce the likelihood of battery failures.