TotalEnergies unveils passive Coolant Keep Plate to boost safety of immersion-cooled EV batteries

TotalEnergies Lubrifiants has developed the Coolant Keep Plate (CKP), a passive component designed to improve the safety of immersion-cooled lithium-ion batteries.

TotalEnergies says direct immersion cooling is a promising approach for lithium-ion batteries under high loads, particularly during fast charging. By eliminating several thermal interfaces between the cells and the cooling system, immersion improves heat transfer and temperature uniformity. It also helps reduce the risk of fire and thermal runaway propagation.

When a cell vents, the gas jet can displace or expel part of the dielectric fluid. The exposed cells then lose the fluid’s thermal protection locally, so propagation can resume.

The CKP is positioned between the cell group and the venting interface, and is designed to promote separation of the gas and liquid phases. Its passive design allows gases to escape while retaining the fluid around the most exposed cells. No sensors, controls or electrical power supply are required.

TotalEnergies says that in tests on several battery configurations, no fire or thermal runaway propagation was observed when the CKP was used, including in scenarios where propagation occurred without it.

The CKP was designed and optimized for TotalEnergies’ own dielectric fluids, but the company says the principle can be adapted to other application areas, cell formats and immersion-cooled battery architectures.

“Immersion alone is not sufficient,” said Gérard Quoirin, Battery Specialist at TotalEnergies Lubrifiants. “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.”

Source: TotalEnergies Lubrifiants