Abstract

Lithium-ion batteries (LIB) are widely used in electric vehicles (EVs) for their high energy density. However, their fire safety causes concerns because of the toxic gases emission and the challenge to extinguish. The type and quantity of toxic gases released during battery fires remain among the least studied hazards, with limited data available despite their serious health risks. This study examines the thermal and gaseous emission behavior of LIB cells after thermal runaway (TR). Five cell types, Lithium Iron Phosphate (LFP), Lithium Titanate (LTO), and three Lithium Nickel Manganese Cobalt oxide (NMC). The three NMC variants share the same base formula (LiNiMnCoO2); NMC1 and NMC3 differ only by manufacturer, while NMC2 has added Ni and Co for enhanced performance. These cells were tested under controlled thermal abuse conditions using a Ni-Chrom resistance wire powered by a DC voltage regulator. Tests were conducted at five states of charge (0 %, 25 %, 50 %, 75 %, 100 % SOC). Temperature profiles and fire/explosion observations were recorded along with the ten types of gas release rates including Carbon Monoxide (CO), Methane (CH4), Carbon Dioxide (CO2), Ammonia (NH3), Ethene (C2H4), Propene(C3H6), Formaldehyde (CH2O), Acrolein (C3H4O), Hydrogen Cyanide (HCN) and Hydrogen Fluoride (HF). CO showed the highest levels of toxic emissions reaching 150–200 L/kWh. Peak emission rates were highest for CO2 across all chemistries. A quantitative risk assessment was performed by combining the measured factors into a risk index (RI). These data were visualized in a color-coded heat map, allowing comparison of overall hazard across chemistries and charge levels. Key contributions include the first systematic measurement of formaldehyde emissions during LIB fires and the introduction of a cell-level safety rating, an actionable safety tool. This study contributes to the understanding of gas emissions during LIB fire, and evaluates the risks related to the types of battery and SOC.

Department(s)

Mining Engineering

Publication Status

Full Text Access

Comments

Centers for Disease Control and Prevention, Grant 75D30120CO8913

Keywords and Phrases

Fire risk assessment; LIB fire; Thermal behavior; Toxic emissions; TR

International Standard Serial Number (ISSN)

0378-7753

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2025 Elsevier, All rights reserved.

Publication Date

01 Nov 2025

Download

Full Text Link

Share

 
COinS