Adsorption and mechanical properties of composite coatings based on zeolite 13× and sulfonated polymer for thermal energy storage in electric vehicles

Electric vehicles will play an increasingly important role in the energy transition in the coming years. One of the main challenges limiting their adoption is the reduced driving range compared to conventional vehicles, which can further decrease by up to 50 % in winter conditions, due to passengers' compartment climate control. A promising technique to mitigate this issue is the use of a thermal storage system based on sorption materials, which enables air heating and dehumidification with significant energy savings. Although the effectiveness of this system has already been demonstrated, further studies are required to ensure the adequate mechanical properties of adsorbent materials, which are subjected to significantly higher stresses compared to stationary applications. In this context, this work focuses on the development of innovative composites based on zeolite 13× and a sulfonated pentablock terpolymer (Nexar) binder. A series of composite coatings were synthesized varying zeolite weight percentages (80–95 wt%). The coatings were applied to aluminium substrates and characterized in order to assess their mechanical, morphological, thermal, and adsorption properties. Results indicate a trade-off between adsorption capacity and mechanical robustness. While higher zeolite content (up to 95 wt%) maximized water vapour adsorption capacity (nearly 28 wt%), it negatively impacted scratch resistance (scratch widths >1300 μm at 500 g load), impact resistance (3.5 mm damage diameter at 160 mJ), and pull-off strength (0.82 MPa). Conversely, coatings with 80–90 wt% zeolite offered a better balance, maintaining reasonable adsorption capacity (22.0–25.9 wt%) while improving mechanical properties. All compounds demonstrated enhanced thermal stability compared to the neat polymer and exhibited excellent adsorption/desorption reversibility, being suitable for the proposed applications in the transportation sector.