Range anxiety is one of the key reasons why Battery Electric Vehicle (BEV) market still has not fully taken off. Users demand EV to be able to fast-charge and travel long distances with short breaks. Ultra-Fast charge appears, therefore, as one of the milestones to reach for widespread electrification. However, such amounts of power, even during short time, require of a proper dimensioning of the system. Thus, the battery must be prepared for such events, controlling cell status during operation to drop the effect of both fast battery degradation and potential dangerous events. Consequently, an increased battery performance requires an adapted battery thermal management system (BTMS) to ensure an uniform temperature distribution in the battery pack especially during fast and ultra-fast charging, to ensure the longest possible battery lifetime. In this paper, the influence of different thermal conductivities of the BTMS on the average battery cell temperature are investigated. The simulation bases on a hybrid 3D/1D model of a module which enables an easy comparison of the impact of the thermal conductivity of the battery cell, thermal pads, heat spreader, and the cooling channels design. The results can be used to determine which measurements have a particularly high influence on the performance of the cooling system. Furthermore, it is possible to identify potential to reduce the weight of the system and keep the environmental impact as low as possible.