Some suppliers of thermal interface materials 57 E-Mobility Engineering | July/August 2026 Thermal interface materials | Product focus C-Therm www.ctherm.com Dow www.dow.com Gravic Group www.gravicgroup.com HB Fuller www.hbfuller.com Henkel www.henkel-adhesives.com KERAFOL www.kerafol.com Laird www.laird.com Parker www.parker.com Saint-Gobain www.tapesolutions.saint-gobain.com Sika automotive.sika.com Solid issues Emerging solid-state batteries promise higher energy density but bring new thermo-mechanical stresses at the interfaces with cooling elements. In today’s lithium-ion cells, TIMs are often designed to accommodate swelling and movement over the battery’s life; however, requirements will be affected by cells that swell in ways different from today’s pouch and prismatic cells. In solid-state systems, the requirement shifts toward maintaining precise, uniform contact in a much less forgiving mechanical environment. Reduced swelling, for example, means less natural compensation for tolerances, increasing the importance of stable contact under controlled pressure. It means that the next generation of TIMs will need to do more than simply absorb motion and deliver a tightly controlled balance of compliance, dimensional stability, thermal performance and long-term interface reliability. The challenge becomes less about managing expansion and more about preserving contact where even small changes at the interface can have a much bigger impact than before. TIMs will be valued less for peak conductivity and more for long-term interfacial stability, compliance and predictable mechanical behaviour over the cell’s lifetime. Also, it is important to distinguish between cell expansion in the horizontal direction, meaning expansion between cells, and the load in the vertical direction, where the TIM is typically located underneath the cells. Expansion is usually more limited vertically, therefore the requirements presented by solid-state batteries probably won’t be a fundamental challenge to TIM developers. From a thermal management perspective, the effect may be more evolution than disruption. For example, future cell designs may guide expansion into specific areas while limiting it in others. If only part of the cell surface can be used for heat dissipation, the available area may become smaller, but this can be compensated with higherperformance thermal materials. For the moment, the needs of solidstate batteries seem to be driving development of highly flexible, solid bonding thermally conductive TCAs with thermal conductivity ranging from 1.3 to 2.0 W/mK. As of the time of writing, this is not significantly different from the performance of battery TIMs leading developers are already developing. Higher energy density will likely increase the demand for better thermal conductivity, but this is already achievable. In power electronics, materials with significantly higher thermal conductivity than those of existing battery TIM solutions are already being used. As with so many areas of technology related to e-mobility, demands on the performance, manufacturability, extended service life and reduced environmental impact of TIMs are making what were once simple products far more complex in terms of the engineering that goes into them. Acknowledgements The author would like to thank Holger Schuh, senior manager, thermal and processing technologies at Henkel; Wolfgang Hoefer, business unite leader at KERAFOL; Eric Wyman, business development manager at Parker, and Shane Thompson, engineer manager, electronic materials technology, also at Parker; and experts at Saint-Gobain. Ongoing developments of TCAs, seen here in a module application, with thermal conductivity between 1.3 and 2.0 W/mK will support future solid-state battery applications (Image: Henkel)
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