Immersion Batteries Explored for Extreme BEV Performance

Paul Myles

TU-Editor

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18th March 2020

Immersing lithium-ion batteries in cooling material is being considered a solution to moderating temperature in high-performance BEVs.

The report from technology analyst IDTechEx Thermal Management for Electric Vehicles 2020-2030 suggests moves by several industry suppliers could change the way automakers design their BEV powertrains. It points out that while most major carmakers are using air or water-glycol cooling methods, some suppliers are turning to new methods to meet the increasing thermal demand on vehicle batteries.

This is especially true specialized markets such as electric construction and mining vehicles, where extremely intense battery discharge is required and, hence, a serious amount of heat is generated. Immersion cooling is one of these emerging technologies for battery thermal management and has been previously demonstrated in electronics for data centers, high-performance computing and grid power systems but is now seeing an opportunity in the electric vehicle market.

Immersion cooling involves submerging the battery cells in a liquid coolant providing superior thermal contact and homogeneity. Also, the flame-retardant nature of the fluids acts as a safety feature, suppressing thermal runaway events before they spread between cells. A key consideration here is obviously the choice of coolant fluid used, through primary research, IDTechEx benchmarks the current fluid options, including those from 3M, Solvay, M&I Materials and Engineered Fluids. These fluids are all dielectrics but vary in their properties with factors such as weight, thermal conductivity, environmental considerations and cost, being extremely important.

The study highlights Xing Mobility are a company specializing in the more niche electric vehicle markets with their modular immersion-cooled battery packs using 3M’s Novec fluid. In another niche market, Rimac Automobili have opted for Solvay’s Galden fluid for their electric hypercars. Whilst the technology shows promise with technically excellent performance; it will be difficult for immersion cooling to enter the mass production automotive market owing to the increased weight and cost compared with currently utilised methods. However, regulations regarding thermal safety of electric vehicles are changing and, with it these emerging technologies, may start to take a more significant market share.

— Paul Myles is a seasoned automotive journalist based in London. Follow him on Twitter @Paulmyles_