Immersion of Electric Vehicle Batteries: The Best Way to Keep Cool?
Mar 20, 2020 Dr James Edmondson
The electric vehicle market is growing rapidly, and with it the demand for fast charging, increased energy density and improved safety. Something that all these areas have in common is heat. Charging a battery quickly generates a lot of heat, with the extra energy capacity of modern and upcoming electric vehicle batteries, extracting this heat becomes more challenging. If this heat is not distributed effectively, not only is the performance and lifetime of the battery greatly reduced, but thermal runaway and vehicle fires are a potential hazard. Immersion cooling is an emerging potential alternative to traditional battery cooling methods and is just one of the topics covered in the Thermal Management for Electric Vehicles 2020-2030 report from IDTechEx.
While most major OEMs in the passenger car market are utilising 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 when considering more specialised markets such as electric construction and mining vehicles, in this scenario 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 centres, high-performance computing and grid power systems, but is now seeing an opportunity in the electric vehicle market.
As the name suggests, immersion cooling involves submerging the battery cells in a liquid coolant, in doing so superior thermal contact and homogeneity can be achieved. Additionally, the flame-retardant nature of the fluids acts as a safety feature, suppressing thermal runaway events before they propagate between cells. A key consideration here is obviously the choice of coolant fluid used, through primary research, IDTechEx benchmark 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.
XING Mobility are a company specialising in the more niche electric vehicle markets with their modular immersion-cooled battery packs utilising 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 due 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.
XING Mobility provide complete drivetrain solutions built around their immersion cooled battery packs which are modular to allow fitting into the required geometry. Source: XING Mobility, IDTechEx Show, Santa Clara 2019.
Immersion cooling is just one of the emerging technologies covered in the recent report from IDTechEx on Thermal Management for Electric Vehicles 2020-2030 which addresses and analyses the currently utilised and emerging strategies for thermal management across the electric vehicle market, with primary information obtained from interviews with relevant companies. In addition to the batteries, the electric motors, power electronics and vehicle charging stations have crucial thermal management considerations, with varying approaches from manufacturers and emerging alternatives, all of which are addressed in this brand new report.
Top image: Pixabay