Kinetic Modeling of the Effects of Fire-Suppressing Electrolyte Additives on Emitted Gas Combustion During Battery Thermal Runaway

IFP Energies nouvelles (IFPEN) est un acteur majeur de la recherche et de la formation dans les domaines de l’énergie, du transport et de l’environnement. De la recherche à l’industrie, l’innovation technologique est au cœur de son action, articulée autour de quatre priorités stratégiques : Mobilité Durable, Energies Nouvelles, Climat / Environnement / Economie circulaire et Hydrocarbures Responsables.

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• l’apport de solutions aux défis sociétaux de l’énergie et du climat, en favorisant la transition vers une mobilité durable et l’émergence d’un mix énergétique plus diversifié ;
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Kinetic Modeling of the Effects of Fire-Suppressing Electrolyte Additives on Emitted Gas Combustion During Battery Thermal Runaway

Context

Electric vehicle is a promising solution to de-carbonization and in recent years a massive deployment is observed, pushed to a large extent by the policy of reducing CO2 emission and dependence on fossil fuels. However, the safety concerns are obstructing their large-scale applications. One of the main safety concerns is the thermal runaway (TR) of Li-ion batteries (LIB), which has caused many accidents around the globe. These accidents often lead to combustion and explosion, presenting dangers to human lives. The fires of TR are particularly dangerous and very difficult to be extinguished from the outside of the battery. They are also easy to re-ignite because not only flammable gas but also oxygen is released internally.

Therefore, fire-suppressing electrolyte additives are becoming a promising solution as it works inside the battery cells. As temperature increases during TR, liquid organic electrolyte solvent evaporates into the gas-phase, contributing by large amount to the total flammable gas released.

If fire-suppressing additives are present in the liquid electrolyte, they are also evaporated and could lower combustion risks by reducing the gas-phase reactivity. Among the common compounds for such additives, fluorinated electrolyte components, replacing some H atoms in the electrolyte solvent molecule by F atoms, have the advantage of being effective without sacrificing battery energy density and performance.

However, a recent study on an additive of such type found that laminar flame speeds are effectively reduced but auto-ignition risks are increased at some conditions. Therefore, a detailed and better understanding is required on the effects of fire-suppressing electrolyte additives on the combustion properties of LIB fires.

Objectives and Methodology

This work aims to study and compare the effects of different fire-suppressing electrolyte additives on the combustion properties of LIB fires by kinetic modeling. The work will include the following:

• A thorough literature review on fire-suppressing electrolyte additives: chemical structures of available and potential additives, their reaction mechanisms, and existing experimental and modeling studies on their effects.
• Selection of additives of interest and develop a kinetic mechanism for their combustion. (Optional: theoretical chemistry computations may be required for mechanism development if literature data is lacking.)
• Kinetic modeling, using the software CHEMKIN, on the combustion characteristics, such as ignition delay time and laminar flame speed, of the electrolyte vapor with and without fire-suppressing additives, and compare their effects.

What you could acquire after the internship

• Knowledge on battery thermal runaway and gas-phase combustion chemistry.
• Skills to perform kinetic modeling using CHEMKIN.

Requested profile and skills:

Level: Bac+5 or Bac+4

• Aptitudes: Taste for research, dynamism and force of proposal, motivation for the valorization of results (writing of scientific articles), ability to work in a team

Duration and dates: 5 months between April and September 2023

Practical information: The internship will take place at IFP Energies Nouvelles in Rueil-Malmaison (west of Paris). The intern will be granted with a financial compensation (unless granted otherwise).

Interested ? Send a letter of motivation and a CV.

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