Lithium-ion batteries offer great energy and power densities but the thermal stability is an issue of concern compared to other battery technologies. In this study different types of abuse testing have been performed in order to compare the battery safety for different types of commercial lithium-ion battery cells. The results show large differences in abuse response for different cells. Exposed to external heating laptop cells with cobalt based cathode developed a thermal runaway resulting in pressure release, fire and temperatures over 700°C. Lithium iron phosphate (LFP) is known to be a very thermally stable cathode material and LFP-cells showed a significantly lower thermal response, a thermal runaway could, however, be detected for some of the cells in the external heating test. The overcharge tests of LFP-cells were in most cases uneventful but in one case the test resulted in a violent fire. The short circuit tests showed modest temperature increases of the cells in spite of high currents peaking at around 1000 A. Although the development of safer lithium-ion battery cells has been successful thermal runaway events may still occur under extreme conditions.