To understand the relationship of the sidewall rupture at different states of charge (SOCs) of cy... more To understand the relationship of the sidewall rupture at different states of charge (SOCs) of cylindrical cells with high specific energy, this work presents the results of radial nail penetration tests of 21700-format cylindrical cells at different SOCs. The thermal runaway and sidewall rupture behaviours were characterised by key performance indicators such as temperature, mass, fire behaviour, and voltage change. In addition, released gases from a subset of tests were measured using the Fourier transform infrared spectroscopy. The change in the internal structure of another subset of cells after the test was observed by X-ray computed tomography. The results show that the sidewall rupture still exists for tests at low SOC (< 30% SOC), but the outcome of thermal runaway and sidewall rupture is milder than those at high SOC (≥ 50% SOC). The average mass loss of cells increases with the increment of SOC. The cell casing thickness is reduced by 12.7% ± 0.3% of the fresh cell, whi...
The research carried out in this report focuses on the topic of safety of Li-ion battery cells, s... more The research carried out in this report focuses on the topic of safety of Li-ion battery cells, specifically for automotive applications. Electric vehicle battery safety is a challenge that must be tackled, especially with the rapid electrification of vehicles. Cell abuse testing simulates their failure process under different scenarios. This helps develop a deeper understanding of the failure process, its root cause and associated mechanisms, hence enabling the improvement of their safety. This research has experimentally investigated four abusive conditions; mechanical penetration, external short circuit, cell swelling as a result of overcharge and overcharge in an adiabatic environment. A number of potential industrial applications based on the research findings are also discussed. During nail penetration testing the effect of nail material and diameter were investigated. Firstly, cells were fully penetrated using 10 mm diameter nails with three different materials; copper, steel...
The present study aims to develop a simplified mathematical model for the evolution of heating-in... more The present study aims to develop a simplified mathematical model for the evolution of heating-induced thermal runaway (TR) of lithium-ion batteries (LIBs). This model only requires a minimum number of input parameters, and some of these unknown parameters can be obtained from accelerating rate calorimeter (ARC) tests and previous studies, removing the need for detailed measurements of heat flow of cell components by differential scanning calorimetry. The model was firstly verified by ARC tests for a commercial cylindrical 21700 cell for the prediction of the cell surface temperature evolution with time. It was further validated by uniform heating tests of 21700 cells conducted with flexible and nichrome-wire heaters, respectively. The validated model was finally used to investigate the critical ambient temperature that triggers battery TR. The predicted critical ambient temperature is between 127 °C and 128 °C. The model has been formulated as lumped 0D, axisymmetric 2D and full 3D...
Nail penetration is an abuse test that is part of most automotive safety test standards, e.g. the... more Nail penetration is an abuse test that is part of most automotive safety test standards, e.g. the Society of Automotive Engineers’ SAE J2464. The main purpose of nail penetration is to test how batteries can withstand two failure mechanisms; internal short circuits and physical damage such as in the case of road accidents. In this research, nails with varying diameters and materials were used to carry out penetration tests on commercial 15 Ah automotive Lithium-ion pouch cells. The voltage and temperature profiles of the cells during penetration were recorded. The data shows significant variability between tests with the same experimental conditions (nail properties, ambient temperature and cell type). It is proposed that the variability is due to the varying way the nail interacts with the penetrated layers of the cell. Therefore, the contact resistance between the bilayers of the cell and the nail varies between each test. Contact resistance cannot be readily measured in nail pene...
Tuberculosis (TB) remains a significant public health issue worldwide especially in developing co... more Tuberculosis (TB) remains a significant public health issue worldwide especially in developing countries, where the disease is endemic, and effective TB diagnostic as well as treatment-monitoring tools are serious barriers to defeating the disease. Detection of pathogen-specific metabolic pathways offers a potential alternative to current methods, which focus on bacterial growth, bacterial nucleic acid amplification, or detection of host immune response to the pathogen. Metabolic pathway detection may provide rapid and effective new tools for TB that can improve TB diagnostics for children and HIV infected patients. Metabolic breath tests are attractive because these are safe, and provide an opportunity for rapid point of care diagnostics and tool for drug efficacy evaluation during clinical trials. Our group has developed a rabbit urease breath test model to evaluate the sensitivity and the specificity of urease based detection of Mycobacterium tuberculosis. TB infected rabbits wer...
To understand the relationship of the sidewall rupture at different states of charge (SOCs) of cy... more To understand the relationship of the sidewall rupture at different states of charge (SOCs) of cylindrical cells with high specific energy, this work presents the results of radial nail penetration tests of 21700-format cylindrical cells at different SOCs. The thermal runaway and sidewall rupture behaviours were characterised by key performance indicators such as temperature, mass, fire behaviour, and voltage change. In addition, released gases from a subset of tests were measured using the Fourier transform infrared spectroscopy. The change in the internal structure of another subset of cells after the test was observed by X-ray computed tomography. The results show that the sidewall rupture still exists for tests at low SOC (< 30% SOC), but the outcome of thermal runaway and sidewall rupture is milder than those at high SOC (≥ 50% SOC). The average mass loss of cells increases with the increment of SOC. The cell casing thickness is reduced by 12.7% ± 0.3% of the fresh cell, whi...
The research carried out in this report focuses on the topic of safety of Li-ion battery cells, s... more The research carried out in this report focuses on the topic of safety of Li-ion battery cells, specifically for automotive applications. Electric vehicle battery safety is a challenge that must be tackled, especially with the rapid electrification of vehicles. Cell abuse testing simulates their failure process under different scenarios. This helps develop a deeper understanding of the failure process, its root cause and associated mechanisms, hence enabling the improvement of their safety. This research has experimentally investigated four abusive conditions; mechanical penetration, external short circuit, cell swelling as a result of overcharge and overcharge in an adiabatic environment. A number of potential industrial applications based on the research findings are also discussed. During nail penetration testing the effect of nail material and diameter were investigated. Firstly, cells were fully penetrated using 10 mm diameter nails with three different materials; copper, steel...
The present study aims to develop a simplified mathematical model for the evolution of heating-in... more The present study aims to develop a simplified mathematical model for the evolution of heating-induced thermal runaway (TR) of lithium-ion batteries (LIBs). This model only requires a minimum number of input parameters, and some of these unknown parameters can be obtained from accelerating rate calorimeter (ARC) tests and previous studies, removing the need for detailed measurements of heat flow of cell components by differential scanning calorimetry. The model was firstly verified by ARC tests for a commercial cylindrical 21700 cell for the prediction of the cell surface temperature evolution with time. It was further validated by uniform heating tests of 21700 cells conducted with flexible and nichrome-wire heaters, respectively. The validated model was finally used to investigate the critical ambient temperature that triggers battery TR. The predicted critical ambient temperature is between 127 °C and 128 °C. The model has been formulated as lumped 0D, axisymmetric 2D and full 3D...
Nail penetration is an abuse test that is part of most automotive safety test standards, e.g. the... more Nail penetration is an abuse test that is part of most automotive safety test standards, e.g. the Society of Automotive Engineers’ SAE J2464. The main purpose of nail penetration is to test how batteries can withstand two failure mechanisms; internal short circuits and physical damage such as in the case of road accidents. In this research, nails with varying diameters and materials were used to carry out penetration tests on commercial 15 Ah automotive Lithium-ion pouch cells. The voltage and temperature profiles of the cells during penetration were recorded. The data shows significant variability between tests with the same experimental conditions (nail properties, ambient temperature and cell type). It is proposed that the variability is due to the varying way the nail interacts with the penetrated layers of the cell. Therefore, the contact resistance between the bilayers of the cell and the nail varies between each test. Contact resistance cannot be readily measured in nail pene...
Tuberculosis (TB) remains a significant public health issue worldwide especially in developing co... more Tuberculosis (TB) remains a significant public health issue worldwide especially in developing countries, where the disease is endemic, and effective TB diagnostic as well as treatment-monitoring tools are serious barriers to defeating the disease. Detection of pathogen-specific metabolic pathways offers a potential alternative to current methods, which focus on bacterial growth, bacterial nucleic acid amplification, or detection of host immune response to the pathogen. Metabolic pathway detection may provide rapid and effective new tools for TB that can improve TB diagnostics for children and HIV infected patients. Metabolic breath tests are attractive because these are safe, and provide an opportunity for rapid point of care diagnostics and tool for drug efficacy evaluation during clinical trials. Our group has developed a rabbit urease breath test model to evaluate the sensitivity and the specificity of urease based detection of Mycobacterium tuberculosis. TB infected rabbits wer...
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