Industry insights of Immersion Cooling

Existing applications of battery immersion cooling to EV’s and energy storage presented mainly on conference presentations and webinars, reflect the fact, that many organizations hold IP in this space and don’t publish their accomplishments in scientific papers. Yet, there is a number of convincing proof-of-concepts and more than 10 EV system suppliers have achieved sustainable progress with battery immersion cooling.

AVL

AVL gave a slight presentation on how they solved some technical limits (timing, cost and complexity) in the process of battery immersion cooling implementation. They managed to reduce the weight and cost of battery module by cooling electrical connections directly. With benchmarks against the ECE-R100 standard, UN Transportation and GB-T 31467-3 tests the safety was also improved.

Ricardo Engineering

A ’turn-key’ battery module with immersion cooling technology is presented at Ricardo Engineering. A high charging rate of 3.9C was accomplished using a 21700 cylindrical cell-based module with M&I MIVOLT fluid. This approach meant, that the the temperature of maximum 30°C could be controlled. On the other side, the same batteries could reach temperatures of up to 50°C within a BTMS using a cold plate cooling with the same C-rate. With the help of thermal runaway test, they were able to explore the module’s safety and as a result an advanced safety improvement over air cooled modules is reached when triggering a cell into TR the temperature was maintained at 70°C. The cost of immersion cooling can be reduced by 8% at module level and 6.5% at vehicle level due to several factors with the main one being cost savings from thickness reduction of copper busbars.

Kreisel Electric

Kreisel Electric raised an efficient and save battery answer combining Kreisel’s laser-welded battery module so includes alone 18650 or 21700 cylindrical cells, fusing, then controlled de-gassing channels including Shell’s proprietary GTL based thermal management fluid, who immerses the battery cells. Kreisel battery system is already being installed in commercial vehicles, such as the London electric bus fleet, industrial applications such as a concrete mixer by Liebherr, and high performance charge posts such as Chimero battery packed EV Fast Charger by Kreisel electric. Additionally, Kreisel battery immersion cooling is planned to be used in motorsport applications such as a battery platform for the Federation Internationale de l’Automobile (FIA) world rally championship hybrid series, and as a technology platform for the FIA World Ralley Cross all electric 1e series from 2022.

Xing Mobility, e-Mersiv and Exoes

Using their IMMERSIO battery module system Xing Mobility developed also a immersive cooling technology. Their solution was proposed in mining, construction and agriculture applications. E-MERSIV and Exoes are tech companies based in France, that developed an immersive BTMS with charge speeds up to 4C for all cell formats (cylindric, pouch and prismatic).

Tesla

Tesla patented a ‘battery coolant jacket’ describing a module with an integrated frame structure to hold battery cells, which are surrounded and cooled directly by a liquid. Another patented module and pack design with increased contact areas between coolant and battery surface was described by Anhui Xinen Technology.

High end luxury cars also start to use battery immersion cooling applications.

McLaren

The new McLaren for example ‘ultimate series’ named as ‘Speedtail’ is the first serial car worldwide to implement immersive cooling technology. Being permanently immersed in a lightweight dielectric fluid allows the cells to achieve greater performance for longer and to improve thermal management. The company claimed, that the Speedtail can generate a total output of 1055 horsepower while the battery pack provides a power density of 5.2 kW/kg.

Besides of McLaren the technology has been designed in the EV retrofits of classic sports cars. In the product specification of their conversion of the classic Alfa Romeo GTV into a high performance BEV, Totem Automobili highlighted their use of 3M Novec to immersion cool the battery back, delivering greater performance for this vintage classic, ensuring its design legacy will last long into the future.

Moveko

Finland based Moveko developed a 120 V DC drivetrain system for public transportation fleet operators including immersion cooled modular battery system suitable for high demands and reliability. Contactless charging technology is being enabled together with a high power ultrafast charging. Besides, AMG showcasted in 2021 a new plug-in hybrid technology adapted from Daimler Formula 1 race car. The 400V HPB80 with 6.1 kWh capacity, 70 kW constant power and a peak power of 150 kW, which is available for a few seconds.

Finally, us at LION Smart developed a light-weight battery pack with integrated immersive cooling technology using 3M Novec fluids, that can be used in automotive or aviation productions. The project is EU funded and a part of LIBAT Clean Sky 2 aiming towards climate neutral aviation by 2050.

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Final Thoughts

Immersion cooling systems remain a promising approach to battery thermal management. This review offers insights into the industrial application of immersion cooling systems and current commercial advances. There will definitely be some more exciting news in this area.

Authors:

Anna Kilischekow

Arne Siegner