Composition and Explosibility of Gas Emissions from Lithium-Ion Batteries Undergoing Thermal Runaway

Abstract

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.

Triggering and Characterisation of Realistic Internal Short Circuits in Lithium-Ion Pouch Cells—A New Approach Using Precise Needle Penetration

“…In the penetration area, a guiding sleeve for the needle is integrated into the bracing plate, thereby minimising electrolyte evaporation from the cell. An air quality sensor is installed in the test chamber, which can detect the typical released gases CO 2 and TVOC (Total Volatile Organic Compounds) during venting of the cell [10,104]. The TVOC concentration is particularly interesting as an indicator for electrolyte evaporation.…”

“…However, the safe operation of LIBs is still a major challenge [5,6]. Due to the limited thermal stability of the cell materials used in LIBs, insufficient heat dissipation can lead to a so-called Thermal Runaway (TR) of the cell, which means an uncontrolled, unstoppable temperature rise and the release of large amounts of toxic and explosive gases [7][8][9][10]. The uniform definition of TR in LIBs is challenging due to the complex and individual characteristics and is the subject of further research [11][12][13].…”

Harmful effects of lithium-ion battery thermal runaway: scale-up tests from cell to second-life modules

“…Experimental data for the heat release rate (HRR) and the total heat release (THR) have been reported in the recent literature. All types of cell geometry (i.e., cylindrical, 9,[47][48][49][50][51][52][53][54][55][56][57][58] pouch, 20,[59][60][61][62][63][64] and prismatic 60,[65][66][67] ) and cathode materials (NMC, 25,[48][49][50]55,58,61,[63][64][65][66]68 LFP, 9,20,48,49,51,[56][57][58][59][60][61]65 NCA, 47,60,69 LCO, …”