Ostfildern-Kemnat, Germany – Wevo-Chemie has developed a liquid polyurethane adhesive system that can dissipate the high temperatures generated in electric vehicle batteries during charging. In the past silicone-based pads were inserted between the cells and the cooling systems, but battery manufacturers now prefer thermal interface materials with adhesive properties. As well as dissipating the heat, the new Wevo system is also a structural adhesive.
As EV system voltages move from 400V to 800V, although the battery charging process is becoming more efficient, high temperatures also occur. The silicone pads do not give adequate heat dissipation as they do not fully compensate for the uneven surfaces of the cells and cooling system. The hotspots that can result risk damaging the cells.
Wevo’s new liquid adhesive systems are flexible, and are applied directly to the cooling system. They are then pressed together with the cells. This prevents air voids from forming, and ensure the heat is dissipated immediately to the cooling system.
The rheological properties of the adhesive systems enable them to be applied as vertical beads that do not collapse, even if the components are tilted or rotated during manufacture. Fillers ensure the viscosity of the potting compound does not rise disproportionately to the thermal conductivity, allowing them to be processed in standard dosing systems.
The materials’ reactivity can be adjusted to meet individual customer processes, enabling fast downstream processing and short production cycles. As they can be used as structural adhesives, in some cases screwed connections can be omitted, helping reduce the battery’s weight and increase its range.
