Thermal elastics extend cell lifetimes

Dow’s new range of thermal adhesives are used in the battery pack of the MG Mulan

Dow has launched a range of thermal elastic high-bonding adhesives to improve safety, sustainability and integrated assembly of EV battery packs (writes Nick Flaherty).

The Voratron MA 8200S adhesives are aimed at bonding cells with insulating bottom shells, upper cover plates and side plate stiffeners, including bottom high-bonding adhesives, upper cover high-bonding adhesives, and side panel high-bonding adhesives.

A low storage modulus in the adhesive provides long-term absorption of vibration energy, and makes batteries safer and more durable.

The adhesives also support bonding between different substrates, such as all-aluminium alloy and composite battery pack casings. As the shell material cannot be welded or riveted, high-bonding adhesives reduce the number of auxiliary parts for reinforcing the ribs of the battery pack, reducing the weight of batteries and the full vehicle.

The adhesives’ asymmetric interface bonding capabilities mean the battery pack lasts far longer, as the interface stress is reduced.

The adhesives are made with a low-hardness filler compound. That helps reduce wear on the mixing equipment using the assembly process, and minimises maintenance checks. They also include an isocyanate to provide greater water resistance than other adhesives.

They can also be cured at a range of different temperatures, from room temperature to higher temperatures for faster curing.

The adhesives have been used in the Magic Cube batteries used in the MG Mulan developed by Shanghai Automotive Industry Corporation. The car’s pack has complex and stringent requirements for material bonding and cell assembly.

The adhesives also include bio-based materials to help reduce the carbon footprint of the assembly. Using an adhesive rather than welding also makes battery pack recycling and disassembly simpler and easier.