Experimental Investigation on Thermal Effects of a Metal Foam-based Frame Application for Lithium-Ion Cells

The use of electric propulsion systems for road vehicle applications is widely recognized as one of the most feasible solutions for sustainable mobility. On the other hand, improvement, and optimization of battery technologies remain challenging technical bottlenecks to be addressed. In particular, the design of proper packaging and heat dissipation structures can greatly support obtaining robust, high energy and power density battery packs. In this regard, this paper presents an experimental analysis of a metal foam-based frame used for the support and cooling of a small battery pack composed of 18650 cylindrical cells. The considered frame is manufactured in Al 6082 alloy according to the lost-PLA replication method. With a double extruder 3D printer it is possible to make polymer-based samples of the lost model. Through CAD modeling, different geometries can be replicated in order to get PLA samples. PLA foams are inserted into a plaster mix, and successively the polymer is thermally burned. The final step consists of the gravity casting of the Al-alloy in the plaster form, obtaining the metal foam-based frame with the same geometry as the 3D-printed PLA foam. The electro-thermal behavior of the cells is investigated with a laboratory test bench in natural convection conditions, with and without the metal foam support to highlight its effect. Specific thermal stress analyses have been performed through charging/discharging pulsed current profiles. Thermal imaging is used as non-contact diagnostics, to detect battery pack and frame temperature without interfering with the heating process. Experimental results highlight the advantages of using the considered metal foam in terms of temperature gradient for the battery pack under investigation. These advantages, combined with the structural characteristics of the metal frame, provide useful insight for future improvements.