A new milestone in battery safety
TotalEnergies Lubrifiants combines advanced fluids and new CKP (Coolant Keep Plate) technology for immersion cooling applications
Paris, October 12, 2026 – TotalEnergies Lubrifiants presents the Coolant Keep Plate, or CKP, a new passive technology designed to enhance the safety of immersion-cooled lithium-ion batteries.Direct immersion cooling is a promising solution for lithium-ion batteries subject to high loads, particularly during ultra-fast charging. By eliminating several thermal interfaces between the cells and the cooling system, it promotes more efficient heat transfer and improved temperature uniformity.
Immersion also helps to significantly reduce the risk of fire and thermal runaway propagation. However, one critical challenge remains: when a cell vents, the gas jet can displace or expel part of the dielectric fluid. The exposed cells then locally lose the thermal protection provided by TotalEnergies fluid,
potentially allowing propagation to resume.
To address this challenge, TotalEnergies Lubrifiants has developed the Coolant Keep Plate. Positioned between the cell group and the venting interface, this plate promotes separation between the gas and liquid phases. Its passive design allows gases to escape while retaining TotalEnergies fluid around the
most exposed cells.
The CKP operates, without sensors, controls or an electrical power supply. Compact and potentially cost-effective to industrialize, it enhances safety without requiring a complex active system.
Combined with the advanced dielectric fluids developed by TotalEnergies Lubrifiants, the CKP delivers a new level of safety for immersion-cooled battery systems. In tests conducted on several battery configurations, no fire or thermal runaway propagation was observed when the CKP was used, including scenarios that propagated without it.“Immersion alone is not sufficient. To preserve thermal protection after the first venting event, the fluid must remain around the initiating cell and the cells that have received the highest thermal load. The CKP was developed to perform this function in a passive manner, while preserving gas evacuation,” explains Dr. Gérard Quoirin, Battery specialist at TotalEnergies Lubrifiants.
Designed and optimized for TotalEnergies Fluids, the CKP principle is versatile and can be adapted to different application areas, any cell formats and immersion-cooled battery architectures.
The Coolant Keep Plate therefore complements the integrated approach developed by TotalEnergies Lubrifiants to improve the safety of immersion-cooled batteries. Our approach combines fluid selection, module thermal capacity, convection paths, vent-gas cooling, depressurization and liquid retention to enhance the overall robustness of the system during thermal runaway.
Designed to the highest thermal runaway safety levels, TotalEnergies fluids, when paired with CKP technology, set a new benchmark for electric vehicle battery protection and safety.