An Experimental Investigation of Thermal Runaway and Gas Release of NMC Lithium-Ion Pouch Batteries Depending on the State of Charge Level

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

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

Effect of waste landfill site on surface and ground water drinking quality

Drinking water quality of surface and underground water within 1.34 km from a waste landfill site in Kumasi, Ghana was investigated. Physico‐chemical properties and heavy metal concentrations were analysed to determine water quality and pollution indices. It was found that turbidity of 83% of hand dug wells, 50% of the streams and 33% of boreholes were higher than World Health Organisation (WHO) standards for drinking water. Water quality index (WQI) showed that 25% of the water sources are of excellent quality, while 50%, 15% and 5% are good quality, poor quality, very poor quality and unsuitable for drinking, respectively. Heavy metal pollution index (HPI) indicated that the water sources were above the critical limit for drinking water (HPI > 100). Principal component analysis (PCA) revealed 75.30% and 70.88% of the total variance for the physico‐chemical parameters and heavy metals, respectively. The findings concluded that cadmium concentrations in all the water sources were extremely higher (0.0122–0.1090 mg/L) than WHO limit (0.003 mg/L), rendering them unwholesome for consumption