Energy Storage Science and Technology ›› 2023, Vol. 12 ›› Issue (7): 2256-2262.doi: 10.19799/j.cnki.2095-4239.2023.0294

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Experiential study on the toxic and explosive characteristics of thermal runaway gas generated in electric-vehicle lithium-ion battery systems

Qinpei CHEN1,2(), Xuehui WANG3(), Wenzhong MI4   

  1. 1.Tianjin Fire Research Institute of MEM, Tianjin 300381, China
    2.Key Laboratory of Fire Protection Technology for Industry and Public Building, Ministry of Emergency Management of China, Tianjin 300381, China
    3.State Key Laboratory of Fire Science, University of Science of Technology of China, Hefei 230026, Anhui, China
    4.Hefei Institute for Public Safety Research, Tsinghua University, Hefei 230601, Anhui, China
  • Received:2023-04-28 Revised:2023-05-12 Online:2023-07-05 Published:2023-07-25
  • Contact: Xuehui WANG E-mail:chenqinpei@tfri.com.cn;wxuehui@ustc.edu.cn

Abstract:

In this study, the gas-composition and ignition characteristics of thermal runaway fires in full-sized electric-vehicle lithium-ion battery systems are investigated. A full-sized electric-vehicle fire-test platform is built, and a gas collection device is designed. The toxic gas composition and ignition characteristics are measured using Fourier transform infrared spectroscopy and an explosion-limit test instrument. The gas release process during an electric vehicle fire is analyzed, and the gas release in the battery compartment is divided into four stages according to the thermal runaway characteristics. The gas-composition characteristics in these four stages are analyzed. In the first stage, electrolyte vapor is primarily released, whereas in the second stage, hydrogen is mainly released. A large amount of sulfur dioxide gas is released in the third stage, with the concentration reaching 10906.4 ppm, and the mechanism of sulfur dioxide generation is analyzed. Hydrogen cyanide gas is produced in the early stages of combustion in a cockpit, with a maximum concentration of 120.4 ppm. The main sources of various toxic gases in the cockpit are analyzed. The explosion limits of the gases in the battery compartment in different stages are measured. The explosion limits of the gases released from the battery compartment range from 4.83% to 73.77%. The explosion hazards calculated for each stage indicate that the second stage of thermal runaway in the battery compartment has the highest explosion hazard. The analysis of variations in explosion characteristics of the gas mixture released from the battery compartment suggests that the inert gas content mainly affects the lower explosion limit of the mixtures, whereas hydrogen content mainly affects the upper explosion limit of the mixture.

Key words: electric vehicle, lithium-ion battery, gas composition, gas explosion risk

CLC Number: