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Meta-analysis of heat release and smoke gas emission during thermal runaway of lithium-ion batteries
(2023)
Herein a meta-analysis of 76 experimental research papers from 2000 to 2021 is given about possible effects on the thermal runaway of lithium-ion battery cells. Data on the hazards of gas emissions and released heat are related to each other and differentiated by cell properties such as, cell geometry, cathode type or state of charge. Quantitative information on the total heat release in the range of 2.0–112.0 kJ Wh−1, the peak heat release rate in the range of 0.006–2.8 kW Wh−1and the smoke gas emission were extracted, normalized in terms of cell energy (Wh), combined in a data library and compared graphically. The total amount of gas emitted (3–48 mmol Wh−1) as well as the released amount of carbon monoxide (1–161 mg Wh−1) and hydrogen fluoride (2–197 mg Wh−1) were investigated as a function of the state of charge and cell geometry. The analysis reveals that the measured values are significantly influenced by the types of calorimeters and smoke gas analyzers used as well as by the type of thermal runaway trigger. This meta-analysis can serve as an important basis for any risk assessment of lithium-ion batteries.
Lithium ion batteries (LIBs) are prone to spontaneous and subsequent fire or explosion resulting from thermal runaway. The vented gases are not only toxic and flammable, their emission can also raise the surrounding pressure rapidly. In this study, characteristic variations of explosion pressure rise, rate of explosion pressure rise and 𝐾(sT)-value have been evaluated. The characteristic 𝐾(𝑠𝑇)-values were determined to evaluate the explosive behavior of LIBs during thermal runaway. The estimated values were compared to that of other explosive substances.
In this study, 19 experiments were conducted with 25 pouch cells of NMC cathode to investigate thermal runaway and the release of gases from lithium-ion batteries (LIBs). Single cells, double cells, and a four-cell battery stack were forced to undergo thermal runaway inside an air-tight reactor vessel with a volume of 100 dm3 . The study involved two series of tests with two types of ignition sources. In the Series 1 tests, a heating plug was used to initiate thermal runaway in LIBs in the ranges of 80–89% and 90–100% SOC. In the Series 2 tests, a heating plate was used to trigger thermal runaway in LIBs in the ranges of 30–50%, 80–89%, and 90–100% SOC. Thermal runaway started at an onset temperature of 344 ± 5 K and 345 K for the Series 1 tests and from 393 ± 36 K to 487 ± 10 K for the Series 2 tests. Peak reaction temperatures ranged between 642 K and 1184 K, while the maximum pressures observed were between 1.2 bar and 7.28 bar. Thermal runaway induced explosion of the cells and lead to a rate of temperature increase greater than 10 K/s. The amounts of gases released from the LIBs were calculated from pressures and temperatures measured in the reactor.
Then, the gas composition was analyzed using a Fourier transform infrared (FTIR) spectrometer. The highest gaseous production was achieved at a range of 90–100% SOC and higher battery capacities 72 L, 1.8 L/Ah (Series 1, battery stack) and 103 L, 3.2 L/Ah (Series 2, 32 Ah cell)). Among the gases analyzed, the concentration of gaseous emissions such as C2H4 , CH4 , and C2H6 increased at a higher cell capacity in both series of tests. The study results revealed characteristic variations of thermal behavior with respect to the type of ignition source used.
Composition and Explosibility of Gas Emissions from Lithium-Ion Batteries Undergoing Thermal Runaway
(2023)
Lithium-based batteries have the potential to undergo thermal runaway (TR), during which mixtures of gases are released. The purpose of this study was to assess the explosibility of the gaseous emission from LIBs of an NMC-based cathode during thermal runaway. In the current project, a series of pouch lithium-based battery cells was exposed to abuse conditions (thermal) to study the total amount of gases released and the composition of the gas mixture. First, the battery cells were placed in a closed vessel, and the pressure and temperature rise inside the vessel were measured. In a second step, the composition of gases was analysed using a Fourier transform Infrared (FTIR) spectrometer.
We found that the amount of released gases was up to 102 ± 4 L, with a clear dependence on the battery capacity. This study showed that the concentration of gaseous emissions such as carbon monoxide (CO), methane (CH4), ethylene (C2H4), ethane (C2H6), and hydrogen cyanide (HCN) increased with higher cell capacity. Of the five studied flammable gases, the maximum concentrations of carbon monoxide (16.85 vol%), methane (7.6 vol%), and ethylene (7.86 vol%) were identified to be within their explosible range. Applying Le Chatelier’s law, a calculated lower explosion limit (LEL) of 7% in volume fraction was obtained for the gas mixture. The upper explosion limit (UEL) of the gas mixture was also found to be 31% in volume. A filter comprising pyrobubbles was used for the removal of the studied gas components released during the thermal abuse. The investigation revealed that the pyrobubbles filter was highly effect in the removal of HCN (up to 94% removal) and CO2 (up to 100% removal). Herein, we report the dependency of the method of thermal runaway trigger on the measured maximum temperature.
This study evaluates the efficacy of compressed air foam (CAF) in comparison to common fire extinguishing media. Newly developed mixed-material burning cribs were used as a normative fire load for extinguishing tests to accurately represent the significantly elevated utilization of synthetic materials in everyday life. A series of outdoor experiments was carried out to analyze the effectiveness of the fire extinguishing medium CAF using synthetical class-A foaming agents from two different manufacturers, and compared them to water and waterfoam solution as a function of the extinguishing distance. In a second series, performed inside a fire room, the efficiency of CAF-usage in indoor fires was evaluated. Moreover, the results of the indoor test series provided information about the composition of smoke gases based on the kind of extinguishing tactic used to suppress the fire. The results showed that under the tested conditions CAF suppressed fire more effectively than both water and water with foaming agents. CAF was able to wet areas hardly accessible to other extinguishing media, and due to its various simultaneously occurring effects and its compact jet with high kinetic energy, it cooled down temperatures more efficiently than water or water-foam solution.
Die Fourier-Transformations-Infrarot-(FTIR)-Spektroskopie ist eine universell einsetzbare Methode zur Rauchgasanalyse. Um verlässliche quantitative Aussagen zu Rauchgaskonzentrationen treffen zu können, müssen die Anforderungen an die FTIR-Spektrometer, die Probenahme sowie die Kalibrierung entsprechend der ISO 19702:2015 eingehalten werden. Im Rahmen dieses Vortrages werden diese Anforderungen sowie die Kalibrierung näher beschrieben und die Reproduzierbarkeit quantitativer Rauchgasmessungen an drei Beispielen beschrieben.
Mischbrandkrippen als Bemessungsbrände zur Unterstützung der Löschwirkung von Druckluftschäumen
(2017)
Dieser Bericht befasst sich mit Bemessungsbränden zur Untersuchung der Effektivität von Druckluftschäumen. Als normative Brandlast wurden dazu neuentwickelte Mischbrandkrippen verwendet. Diese Krippen sollen den steigenden Anteil synthetischer Materialien im Alltag wiederspiegeln und somit hohe Anforderungen an das Löschmittel stellen. Dieses Paper behandelt die Vorbereitung, Durchführung und Auswertung von zwei Versuchsreihen sowohl im Outdoor- als auch im Indoor-Bereich. Das Paper befasst sich mit der Untersuchung der Effektivität des Löschmittels Druckluftschaum im Vergleich zu Wasser und Netzwasser anhand von acht Outdoor- und vier Indoor-Mischkrippenbränden. Aus den In-door-Brandversuchen gehen zudem Aussagen über die Rauchgaszusammensetzung während des Brandverlaufes hervor. Die Ergebnisse der Bemessungsbrände zeigen, dass Druckluftschäume aufgrund ihrer zeitgleich wirkenden Löscheffekte, unter den getesteten Bedingungen eine bessere Brandunterdrückung erzielen, als herkömmliche Löschmittel.
Dieser Bericht befasst sich mit Bemessungsbränden zur Untersuchung der Effektivität von Druckluftschäumen. Als normative Brandlast wurden dazu neuentwickelte Mischbrandkrip-pen verwendet. Diese Krippen sollen den steigenden Anteil synthetischer Materialien im Alltag wiederspiegeln und somit hohe Anforderungen an das Löschmittel stellen. Dieses Pa-per behandelt die Vorbereitung, Durchführung und Auswertung von zwei Versuchsreihen sowohl im Outdoor- als auch im Indoor-Bereich. Das Paper befasst sich mit der Untersu-chung der Effektivität des Löschmittels Druckluftschaum im Vergleich zu Wasser und Netzwasser anhand von acht Outdoor- und vier Indoor-Mischkrippenbränden. Aus den In-door-Brandversuchen gehen zudem Aussagen über die Rauchgaszusammensetzung während des Brandverlaufes hervor. Die Ergebnisse der Bemessungsbrände zeigen, dass Druckluft-schäume aufgrund ihrer zeitgleich wirkenden Löscheffekte, unter den getesteten Bedingun-gen eine bessere Brandunterdrückung erzielen, als herkömmliche Löschmittel.
The joint research project AERIUS (BMBF), is working to determine the effectiveness and efficiency of CAF in comparison to pure water, water with foaming agents and nozzle-aspirated foams in an extensive series of firefighting experiments. The poster deals with a series of extinguishing tests with mixed-material burning cribs.
