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Manufacturing Technology Insights | Tuesday, February 21, 2023
Battery design for electric vehicles (EVs) continues to focus on thermal management.
FREMONT, CA: Thermal management remains essential to electric vehicle (EV) battery development. Early market trends centered primarily on adopting active cooling for the battery pack, now the industry standard. However, batteries, motors, and power electronics in EVs continue to evolve, with cell-to-pack designs, directly oil-cooled motors, and silicon carbide power electronics being a few of the key trends that will impact thermal strategies across the key driveline components in an EV. As the thermal management market evolves, opportunities present themselves for material companies, component suppliers, vehicle designers, and other participants in the rapidly expanding EV industry.
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The new Thermal Management for EVs report from IDTechEx examines the EV market and the thermal management strategies adopted by OEMs and their suppliers, with an eye toward the future and how key EV technology trends will impact these strategies for electric vehicle batteries, motors, power electronics, and charging infrastructure.
Battery Design Trends
Increasing energy density and reducing costs are the primary factors in EV battery development. This is made more difficult by supply chain shortages and rising material costs, but battery designs are becoming simpler as designers begin to eliminate non-cell materials. This strategy yields cell-to-package or cell-to-body designs. Cell-to-pack eliminates module enclosures in favor of stacking all of the cells together. With cell-to-body, the battery becomes a structural component of the vehicle. There are currently designs on the road, with additional announced designs coming to the market shortly. How does the removal of so much from the pack affect thermal management?
Active Cooling and Industry Trends
Some active cooling strategies will stay the same, with a large cold plate beneath or above the cells but now in direct contact with the cells instead of the module housing. Cells with a larger form factor are becoming more prevalent in cell-to-pack designs, which is the most significant shift. Due to the larger form factor, fewer induvial cells are required per pack. This is evident in BYD's Blade battery, which contains highly long prismatic cells, and Tesla's use of larger cylindrical 4680 cells. These modifications reduce the number of individual coolant channels required compared to earlier designs. BYD uses a single large cold plate across the top of the pack, whereas Tesla can now use 12 coolant lines for side wall cooling cells, as opposed to 28 in the 2170 packs.
The transition to active liquid battery cooling has occurred faster than many predicted, including IDTechEx. In the first half of 2022, over 70 percent of the market for electric vehicles utilized liquid cooling. Greater thermal performance and integration with the thermal management system of the entire vehicle have outweighed the reduced complexity of air cooling. However, refrigerant cold plate cooling adoption has increased, gaining a 6.5 percent larger market share in 2022 than in 2021. While conventional automotive coolants and refrigerants have been used to date, there is a growing interest in customizing these coolants for EVs, with reduced electrical conductivity being one of the new characteristics. Regarding kWh demand, the latest report from IDTechEx forecasts the adoption of air, liquid, refrigerant, and immersion cooling for EV batteries.
Thermal Interface Materials
Design integration also significantly affects thermal interface material (TIM) utilization, favoring thermally conductive adhesives for structural connections instead of the gap filler utilized in many existing designs. The new IDTechEx report contains projections for EV battery gap pads, gap fillers, and thermally conductive adhesives.
The "Thermal Management for Electric Vehicles 2023-2033" report by IDTechEx collects data from primary and secondary sources throughout the EV industry. For thermal management strategies in batteries, motors, and power electronics, market shares and forecasts are provided, as well as material forecasts for immersion, TIMs, and fire protection.
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