Thermal management of 4680 battery cells: Cell design and cooling concept

Leading OEMs and cell manufacturers have announced cylindrical cells with a diameter of 46 mm for the next generation of their batteries. The thermal management of these cells is challenging, especially under fast-charging conditions, since the smaller surface-to-volume ratio exacerbates thermal gradients within the cell. This work investigates the thermal performance of a state-of-the-art 4680 battery cell with a tabless design and steel housing. We experimentally show that side cooling (SC) is superior to bottom cooling (BC) regarding the surface temperatures. Based on this, a thermal simulation model is implemented to optimize the cell design and the thermal management concept. The design of the electrical tabs and the housing material significantly influence the thermal performance. For BC, it is recommended to further improve the thermal conductivity of the tab at the cooled surface or use an aluminum housing, whereas SC performs well with the current cell design. The cooling of the whole mantle surface, as it is often discussed in the context of immersion cooling, provides a further improvement. The analysis of the electrical contact resistance from the busbars to the cell terminals shows that the heat input cannot be neglected. Especially at high currents and a single-sided contact of both terminals, it is challenging for BC. These results show that the holistic optimization of the cell design and the cooling concept are of utmost importance.