Thermal runaway characterization of cylindrical lithium-ion and sodium-ion batteries with various sizes and energy contents
Jan Schöberl, Sebastian Ohneseit, Stefan Schaeffler, Dominic P. Förstermann, Linus Grahl, Andreas Jossen, Carlos Ziebert, Markus Lienkamp
Abstract
Extensive thermal runaway characterization is essential in battery development, requiring an analysis of multiple parameters for safety assessment. This paper presents an approach for a comprehensive thermal runaway characterization based on experimental data from accelerating rate calorimetry (ARC) and discretized autoclave thermal runaway calorimetry (DATRC). The method is applied to lithium-ion and sodium-ion batteries in the cell formats 18650, 21700, and 4680. The comparative analysis regarding thermal stability identified LFP as the cathode material with the highest stability. Furthermore, the heat release of NMC-811 and NFM show similar results regarding normalized heat release and energy fraction, while the LFP cells release less heat, and the fraction can vary greatly. A comparison between mass and energy fractions revealed that mass loss correlates with the energy released via gas and ejecta, but mass and energy flow do not necessarily have to be directly proportional, which can result in differing mass and energy fractions. A venting gas analysis, indicating an increased gas production for NMC-811 and NFM compared to LFP, finalizes the safety assessment. Overall, the presented approach and results provide a procedure and data basis for an extensive assessment of battery cells during cell selection, paving the way for accelerated safety-related battery design.