Li-ion batteries have become an integral part of modern technology in recent decades, particularly in mobile devices and the automotive industry. The demand for higher energy density per unit of weight or volume has led to considerable progress in recent years. At the same time, various innovations in battery shape, size and electrochemistry have been driven forward to further improve life cycle performance and safety. However, these advances pose new challenges for battery module manufacturers, particularly in the evaluation the safety of the cells they integrate into their systems. Innovative approaches are needed to overcome these challenges, which led to the establishment of the scientific project program “BattLab.” This program consists of three interconnected projects aimed at enhancing the thermal runaway detection in battery systems, evaluating advanced materials for the mitigation of thermal propagation between cells in a module, and simulating the thermomechanical behavior of cells throughout their lifecycle. These efforts are critical for assessing risks in high-stress scenarios, such as crashes or impacts, and for enabling the efficient development of next-generation battery technologies.

The first of three major goals within the BattLab program is the development of thermo-active polymers that release tracer molecules when exposed to thermal runaway conditions. These polymers can be applied as coatings on individual battery cells within a system, enabling the detection of thermal events by integrated sensors in the battery module. This eliminates the need for individual sensors on each cell and allows the battery management system to respond effectively by deploying cooling agents or issuing warnings to users.

The second major goal in BattLab is the development of innovative characterization methods. One example is the creation of a testing site to evaluate materials designed to mitigate thermal propagation between cells. This testing site simulates thermal runaway conditions, achieving temperatures of up to 850°C, to accurately measure thermal diffusion properties. This setup will enable a robust evaluation and quantitative comparison of thermal propagation materials, supporting accurate simulations of thermal behavior in battery modules. Another example is the application of a compressibility test rig manufactured by Zwick-Roell. This testing site bridges the gap between nano-indentation and universal testing machines, offering the ability to apply stresses up to 400 MPa with high repeatability while maintaining the precision required to measure individual electrode sheets. This eliminates the need for stacked samples, which can cause substantial measurement errors due to air gaps and alignment issues between layers.

The third major goal is the implementation of a multi-scale, multi-physical thermomechanical simulation of an entire battery system. As a foundation, a detailed numerical finite element model of individual cells will be developed to simulate stress and strain responses to loads or impacts and predict the onset of a thermal runaway event. Experimental data on the tensile, compressive, and thermal properties of battery cells will determine the simulation’s input parameters. Based on the outputs of this detailed finite element model, surrogate models with reduced computational demands will be constructed to enable efficient simulation of entire battery systems. This approach provides a balance between accuracy and computational feasibility and enables predictions about the thermomechanical behavior of battery systems during their life cycle as well as the risks of thermal runaway during intended or abusive use. The integration of the findings from the other projects will improve the accuracy and relevance of these system-level simulations.