Similar to hydrogen fluoride (HF), carbon monoxide (CO) and carbon dioxide (CO2) are common toxic gases that are released in the burning of LIB (Peng et al., 2020 ). CO is one of the two asphyxiant gas in ISO 13571 (Peng et al., 2020).
ISO 13571:2012 establishes procedures to evaluate the life-threatening components of fire hazard analysis in terms of the status of exposed human subjects at discrete time intervals. – (International Organization for Standardization, 2020)
What is an asphyxiant gas?
Asphyxiant gas is a gas that results in hypoxia, the decrease of oxygen level in body tissue (Cleveland Clinic, 2022), by disarranging oxygen in the respiratory system (Gold, 2022). Besides hypoxia, asphyxiant gases will also cause ischaemia and metabolic acidosis (Gold, 2022; Cowled, 2011). Ischaemia causes deficiencies in blood oxygen, glucose and other substances (Cowled, 2011). When the supply of blood is lower than the demand, the body is no longer able to support essential normal functions (Cowled, 2011). The decrease in blood oxygen and other key substances deranges metabolic function which plays a crucial role in converting food and water into energy in the body (Cowled, 2011; Schoeller & Fjeld, 1991). On the other hand, metabolic acidosis is the buildup of acid in the body when the kidney is unable to remove enough acid in time due to failure (Gold, 2022).
Symptoms:
- Headaches, vomiting, lethargy, confusion
- Loss of appetite
- Chest pain
- Shortness of breath
- Fast heart rate
- Loss of consciousness
- Cardiac arrest
The symptoms a person suffers from by inhaling CO vary according to the concentration of CO and the duration they are exposed to. Furthermore, the deleterious effects of CO can be amplified when CO2 is breathed in with CO (Peng et al., 2020). As both of these gases are produced in conjunction with the burning of batteries, the effects of CO will be intensified.
According to CO2 Meter (2023), the duration before CO takes effect significantly reduces when the concentration of CO exceeds 200 ppm (Figure 1).
Figure 1: Carbon monoxide levels chart (CO2 Meter, 2023)
Burning behaviours of a 68 Ah battery (Figure 2) was studied by Peng et al. (2020) at different state of charge (SOC) and the concentration of CO and CO2 released over time was studied (Figure 3).
Figure 2: 68 Ah lithium iron phosphate battery (Peng et al., 2020)
Figure 3: Experimental setup (Peng et al., 2020)
Batteries at a higher SOC produced the maximum CO and CO2 in the shortest duration after the battery started burning (Peng et al., 2020) (Figure 4). CO production reached a maximum of 258 ppm for 100% SOC albeit for a very short duration (Peng et al., 2020).
Figure 4: Graphs of CO and CO2 production (Peng et al., 2020)
Although this concentration of CO will not have immediate health impacts when exposed to such a short period of time (Figure 1), we must bear in mind that this experiment used a 68 Ah battery with a nominal voltage of 3.22 V (Peng et al., 2020). According to E.ON, (n.d.), the battery capacity of an electric car (EV) is around 40 kWh with some going as high as 100 kWh and the common voltage of the batteries are 280 V and 360 V (Matsusada Precision Inc., 2019). A battery with a capacity of 40 kWh and voltage of 280 V will have a current of 143 Ah, more than double the current of the battery used in the experiment. Burning this battery will most likely increase the concentration of CO and CO2 produced to a lethal concentration that is fatal within minutes of exposure (Figure 1).
Reference List
Cleveland Clinic. (2022). Hypoxia: Causes, Symptoms, Tests, Diagnosis & Treatment. https://my.clevelandclinic.org/health/diseases/23063-hypoxia#:~:text=Hypoxia%20is%20low%20levels%20of,Hypoxia%20can%20be%20life%2Dthreatening
CO2 Meter. (2023, January 23). Carbon Monoxide Levels Chart. https://www.co2meter.com/blogs/news/carbon-monoxide-levels-chart
Cowled, P. (2011). Pathophysiology of Reperfusion Injury. Mechanisms of Vascular Disease – NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK534267/#:~:text=Ischaemia%20occurs%20when%20the%20blood,begin%20during%20this%20ischaemic%20phase
E.ON. (n.d.). Electric vehicles | Battery | Capacity and Lifespan. https://www.eonenergy.com/electric-vehicle-charging/costs-and-benefits/battery-capacity-and-lifespan.html#:~:text=The%20average%20capacity%20is%20around,higher%20the%20kWh%20the%20better
Gold, A. (2022, September 26). EMS Asphyxiation And Other Gas And Fire Hazards. StatPearls – NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK519487/
International Organization for Standardization. (2020). ISO 13571:2012. ISO. https://www.iso.org/standard/56172.html
Matsusada Precision Inc. (2019, June 4). Power Supply and Voltage of EV Motor | Tech | Matsusada Precision. Matsusada Precision. https://www.matsusada.com/column/ev-power.html#:~:text=Lithium%2Dion%20batteries%20are%20the,connected%20in%20series%20and%20parallel
Peng, Y., Yang, L., Ju, X., Liao, B., Ye, K., Li, L., Cao, B., & Ni, Y. (2020). A comprehensive investigation on the thermal and toxic hazards of large format lithium-ion batteries with LiFePO4 cathode. Journal of Hazardous Materials, 381, 120916. https://doi.org/10.1016/j.jhazmat.2019.120916
Schoeller, D. A., & Fjeld, C. R. (1991). Human Energy Metabolism: What Have We Learned from the Doubly Labeled Water Method? Annual Review of Nutrition, 11(1), 355–373. https://doi.org/10.1146/annurev.nu.11.070191.002035