The thermal conductivity of aluminium = 236W/m.K, the thermal conductivity of a typical TIM ~ 2W/m.K a quite poor thermal conductor. However, no surfaces are flat and the thermal conductivity of air = 0.024W/m.K a good insulator. In the units for thermal conductivity you will see that this is per unit thickness of the. If you are using a gap pad type of TIM then you need it to be compressible so that it can comply to the variation in distance between the two surfaces. You will also need some spring force in the material so that it can. In any battery pack design you need to consider all of the materials, chemicals and gases that might be present in the battery and in the. It is important that these materials interface with all surfaces as designed. Some materials will be easier to apply than others depending on your design. Therefore it is important to. In the case of a battery cell going into thermal runaway it is important that the surrounding materials do not add to the overall combustion. This includes the TIM materials. If the pack is.