Lab-scale versus industrial-scale thermal runaway tests for lithium-ion battery cells

Lithium-ion battery safety is a topic of large importance, and testing is associated with large costs. Safety evaluation is therefore needed also at an early stage in cell design and development, in order to evaluate potential short-comings or to screen large platforms of materials and cells. Previous thermal runaway tests on lab-scale cells have, however, indicated differences in heat release and temperature increase as compared to commercial cells. On the other hand, these could also vary between different commercial cells due to differences in cell materials, size, format, and design. In this work, thermal runaway characteristics of industrial-scale cells are compared against each other as well as with lab-scale cells. Tests were performed on lab-scale coin cells and five different industrial-scale cells ranging from 5 to 157 Ah, covering different cell formats and materials. The coin cells were built using electrodes and separator extracted from one of the industrial-scale cells. The results show that the thermal runaway will be less violent and reach lower maximum temperatures using lab-scale cells, depending on the lower proportion of active materials as compared to inactive components. It is also shown that the ratio between cell capacity and heat capacity is a useful indicator for the comparability of thermal runaway scenarios. This ratio varies considerably for small cells, but not so much for different commercial cells. The data available suggests that a cell capacity of at least 1 Ah is needed to achieve a good comparison of the thermal runaway scenario with larger commercial cells. • Thermal runaway scenarios are different in lab-scale compared to industrial-scale. • Thermal runaway is less violent and reaches lower maximum temperatures in lab-scale. • The ratio of cell capacity to heat capacity is a useful indicator of comparability. • Typically, cells smaller than 1 Ah have too low ratio of active materials.