(5b) Characterisation of Thermal Response and Gas Generation Products of Li-Ion Cells Under Abusive Conditions

The number of lithium-ion battery applications continues to increase rapidly. Commercially available lithium-ion batteries contain a multitude of harmful and flammable substances. Despite intense safety measures, incidents might occur. This demands a better understanding of potential risks of this technology that could arise under critical conditions. Studies and models have already given a good understanding of cell behaviour under abusive treatment [1,2,3].

Based on this knowledge a flexible test rig was constructed in the laboratory, which allows the investigation of thermal response and gas generation products of various commercially available consumer cell formats and cell types in an open reactor. In the reactor, commercial lithium-ion pouch cells are heated up far beyond their specified temperature rating until the self-reaction within the cells is initialised. The so called thermal runaway is then observed in the experiments. The generated heat is measured and the produced gases are analysed. The on-set temperature that indicates the beginning of the thermal runaway reactions, the self-heating rate of the battery and the maximum temperature are determined. The decomposition reactions that occur at the cathode and anode side are derived from the gas chromatographic analyses of the ventilated gases.

The gas compositions of each gas sample together with the observed temperature profiles give a better understanding of the influence of cathode material, cell format and state of charge on the thermal runaway characteristic.

Acknowledgment
The authors would like to acknowledge the financial support of the ”COMET K2 - Competence Centres for Excellent Technologies Programme” of the Austrian Federal Ministry for Transport, Innovation and Technology (BMVIT), the Austrian Federal Ministry of Economy, Family and Youth (BMWFJ), the Austrian Research Promotion Agency (FFG), the Province of Styria and the Styrian Business Promotion Agency (SFG).
The project was supported by the following industrial partners: Magna Steyr Battery Systems GmbH & Co OG and by BASF SE.

Reference
[1] Can-Yong Jhu, et al., Thermal runaway potential of LiCoO2 and Li(Ni1/3Co1/3Mn1/3)O2 batteries determined with adiabatic calorimetry methodology, Applied Energy 100 (2012), 127–131.
[2] Kong W., et al., Gas evolution behaviors for several cathode materials in lithium-ion batteries, Journal of Power Sources 142 (2005), 285–291.
[3] Abraham D.P., et al., Diagnostic examination of thermally abused high-power lithium-ion cells, Journal of Power Sources 161 (2006), 648–657.