Prismatic cells are typically surface-cooled when used in real world scenarios, and we have observed a growing demand for testing methods that align to this. Thus we have been investigating the best methods for replicating the conditions a battery may be used in. Recently, we conducted a surface cooling test on a 314Ah prismatic cell. Using a cooling plate we observed a notable result: cooling the side of the cell was significantly more efficient than cooling the base, despite both surfaces having similar dimensions.
Our Investigation
To quantify the impact of surface cooling orientation, we performed a controlled experiment on a 314Ah LFP prismatic cell, testing two distinct configurations. In the first, the cooling plate was applied to the base edge of the cell, whilst in the second the cooling plate was on the side edge. Each test was conducted over five hours to evaluate the thermal performance measured. The cooling plate was set to -30°C and the test was performed at 23°C ambient temperature.
- Cooling Plate:
- Size: 305 x 178 x 15mm (LxWxH)
- Material: Aluminium
- Prismatic cell:
- 314Ah LFP prismatic cell
- Size: 174 x 72 x 205mm (LxWxH)
Figure 2: Diagram of setup
Results
The results showed a significant difference in cooling performance between the two orientations. The side edge cooled cell cooled more quickly, reaching thermal equilibrium by 5 hours, whereas the base edge cooled cell was still cooling at this point. Additionally, the temperature gradient across the side edge cooled cell was lower during the cooling process, indicating more efficient and even heat dissipation.
These findings highlight the impact of internal cell geometry on cooling effectiveness. The current collectors conduct heat the best inside a cell. Due to the internal structure of the cell, the current collector may be closer to the side of the cell than to the base, and also present a larger area of contact for heat conduction. Hence, the orientation of the cooling surface in relation to the cell internal geometry directly affects heat transfer efficiency. Optimising cooling performance requires not only enhancing cooling capacity but also strategically managing where heat is extracted from the cell.
Cognition Energy provides characterisation & performance cell testing, along with cell testing equipment. With over 600 testing channels (up to 1600A), and the ability to work with all cell sizes and chemistries, our services are designed to empower your next project. Our battery holders are designed for flexibility, precision and safety.
See also: Thermal Management System, Prismatic Cells