TotalEnergies Develops Passive Coolant Keep Plate for Immersion-Cooled Batteries
The component retains dielectric fluid during cell venting to prevent thermal runaway propagation without using sensors or power.
TotalEnergies Lubrifiants has developed the Coolant Keep Plate (CKP), a passive component designed to improve the safety of immersion-cooled lithium-ion batteries.
What Happened
TotalEnergies identifies direct immersion cooling as a promising approach for lithium-ion batteries under high loads, particularly during fast charging, because it eliminates several thermal interfaces between the cells and the cooling system. This improves heat transfer and temperature uniformity while helping to reduce the risk of fire and thermal runaway propagation. However, when a cell vents, the resulting gas jet can displace or expel part of the dielectric fluid. This loss of fluid contact leaves exposed cells without local thermal protection, allowing propagation to resume. The CKP is positioned between the cell group and the venting interface to promote the separation of gas and liquid phases. Its passive design allows gases to escape while retaining the fluid around the most exposed cells, requiring no sensors, controls, or electrical power supply.
Why It Matters
The development addresses a specific vulnerability in immersion cooling systems where the loss of fluid after an initial venting event can lead to battery failure. In tests conducted by TotalEnergies on several battery configurations, the company reports that no fire or thermal runaway propagation was observed when the CKP was used, including in scenarios where propagation occurred without the component. While the CKP was designed and optimized for TotalEnergies’ own dielectric fluids, the company states that the principle can be adapted to other application areas, cell formats, and immersion-cooled battery architectures. Gérard Quoirin, a Battery Specialist at TotalEnergies Lubrifiants, emphasized that immersion alone is not sufficient and that preserving thermal protection after the first venting event is critical.
The Bottom Line
TotalEnergies’ Coolant Keep Plate offers a passive solution to maintain thermal protection in immersion-cooled batteries during venting events, potentially reducing fire risks without adding active components or power requirements.
