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Aluminium Material Solutions for Battery Cooling Plates
Aluminium is a highly versatile material providing a multiplicity of great properties, such as high thermal conductivity, lightweight, high formability, strength and recyclability, that are crucial for the thermal management of battery systems in battery electric vehicles (BEV).
Modern high-capacity lithium-ion battery systems rely on efficient liquid-cooling systems to maintain their safe operating temperature range under all conditions. Among several technical solutions to provide the cooling for battery cells large brazed aluminium cooling plates have gained wide acceptance due to their balance of efficiency and cost.
The aluminium industry provides a wide range of material solutions for the manufacturing of brazed battery cooling plates from cost efficient standard materials to advanced high strength materials. In this paper the requirements for materials are discussed and a guideline for the material selection is given.
Speira learn
Aluminium Material Solutions for Battery Cooling Plates
Aluminium is a highly versatile material providing a multiplicity of great properties, such as high thermal conductivity, lightweight, high formability, strength and recyclability, that are crucial for the thermal management of battery systems in battery electric vehicles (BEV).
Modern high-capacity lithium-ion battery systems rely on efficient liquid-cooling systems to maintain their safe operating temperature range under all conditions. Among several technical solutions to provide the cooling for battery cells large brazed aluminium cooling plates have gained wide acceptance due to their balance of efficiency and cost.
The aluminium industry provides a wide range of material solutions for the manufacturing of brazed battery cooling plates from cost efficient standard materials to advanced high strength materials. In this paper the requirements for materials are discussed and a guideline for the material selection is given.
Introduction
Lithium ion battery (LIB) cells only have a narrow window for their optimal operating temperature between 20°C and 40°C. As illustrated in Figure 3, lower temperatures result in a loss of capacity while higher temperatures will lead to aging and the risk of a thermal runaway. Heat will be generated in the LIB cells during the charging and discharging process and has to be dissipated, whereas in cold environments a heating of the battery system is beneficial to increase the available capacity and to minimize aging during charging. Thus, a sophisticated thermal management system is required to keep the battery system of a BEV in the required temperature range under all operating conditions.
Liquid-cooled lithium-ion battery pack with aluminium cooling plates on top.
A basic design of modern BEVs’ thermal management systems is shown in Figure 4. The battery cooling loop (yellow lines) uses a liquid coolant, whose temperature is controlled via a chiller in the air conditioning loop (blue). Often the system is more complex and comprises also a PTC heater (Positive Temperature Coefficient) and an additional liquid cooling loop with a low temperature radiator.
Basic types of battery cooling systems
The heat transfer between the LIB cells or modules and the liquid coolant is typically accomplished by either tube or cold plate based cooling systems.2
In a tube liquid cooling system, a flat tube is positioned between the individual LIB cells as illustrated in Figure 5. This setup extracts heat through the sidewall of the cells and is suited best for cylindrical cells in a hexagonal arrangement. In practice serpentine shaped tubes are positioned between the cylindrical cells for better thermal contact and increased packing density.
![](https://assets.foleon.com/eu-central-1/de-uploads-7e3kk3/49182/fig_5.bbf003f654d6.jpg?)
Figure 5: Schematic illustration of Tesla’s tube liquid cooling system.
The flat tubes are generally extruded flat aluminium tubes which contain a plurality of parallel micro-channels, so called Multi Port Extruded (MPE) tubes.
Liquid cold plates find widespread use in battery systems based on prismatic battery cells. The plates contain internal channels through which the coolant flows and extracts the heat. The plates can be placed between individual cell modules to optimize the heat transfer, but in the most common application one or several large cooling plates are used as an insert in a battery tray on which the battery modules are placed (see Figure 6).
![](https://assets.foleon.com/eu-central-1/de-uploads-7e3kk3/49182/cooling_whitepaper_assemblytray_kopie_pfeile.d6046a36f548.png?)
Figure 6: Battery system with a liquid cooled cold plate (a) positioned under the battery modules (b).
Such cooling plates are typically made from aluminium sheet and consist of two major components as shown in Figure 7: A flat base plate, which is the heat transfer interface to the battery modules, and a channel plate with a deep-drawn channel structure providing the cavities for the circulation of the coolant. Both plates are commonly joined by brazing. However, it should be noted that alternative joining technologies such as laser welding and adhesive bonding are under consideration.
![](https://assets.foleon.com/eu-central-1/de-uploads-7e3kk3/49182/cooling_whitepaper.16861d919bbc.png?)
Figure 7: Schematic illustration of a battery cooling plate made from two main components, a flat base plate acting as thermal interface to the battery modules, and a structured plate with a deep drawn channel structure (blue) for the circulation of a liquid coolant.
Outlook to further developments in battery cooling systems
Development of battery system is progressing at a fast pace. Expected trends are an increasing integration of the cooling plates into the structure of the battery system or even the car. Parallel to this the current cell-to-module battery configurations are expected to develop to cell-to-pack and cell-to-chassis designs.4 Both trends target optimized battery packs for size, space requirements and cost and will have a severe impact on the requirements of the materials used. The following overview will show how advanced aluminium materials provide innovative solutions for both current and future battery cooling systems.
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Aluminium Material Solutions for Battery Cooling Plates
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