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MM: Fachverband Metall- und Materialphysik

MM 40: Focus Session: Battery Materials – Experimental Characterisation and Safety Testing (joint session KFM/MM)

MM 40.4: Talk

Wednesday, March 20, 2024, 16:10–16:30, EMH 225

Comparison of thermal safety of new and aged commercial 21700 lithium-ion batteries with different cathode materials by Accelerating Rate Calorimetry (ARC) — •Sebastian Ohneseit, Nils Uhlmann, Hans Jürgen Seifert, and Carlos Ziebert — Karlsruhe Institute of Technology (KIT), Institute for Applied Materials - Applied Materials Physics (IAM-AWP), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany

Cylindrical lithium-ion batteries (LIB) of type 21700 have multifaceted usage applications, such as consumer goods, battery electric and hybrid electric vehicles. In consequence, their safety in new and aged state is of particular interest. In this experimental study, the different cathode materials NMC, NCA and LFP were compared, as well as high power and high energy cells. Calendar and cyclic aging with different test conditions (temperature, discharge rate) was performed on the listed cell types and subsequently safety tests were performed on the aged cells, in comparison to results of new cells of the same type. Thermal abuse was done by the heat-wait-seek test in an Accelerating Rate Calorimeter (ARC). Several critical temperatures and temperature rates, as well as exothermal data, were determined. Furthermore, the grade of destruction and mass loss was determined, and all data was compared for aged and unaged cells. It was found that, for aged NMC and NCA cells, the aging parameter modified the exothermal reaction onset and overall, a lower maximum temperature was found for the aged cell state. LFP cells reacted, as expected, at significantly higher temperatures, making the cell chemistry considerably safer.

Keywords: battery safety; Accelerating Rate Calorimetry; heat-wait-seek test; abuse testing; thermal analysis