from chemistry to pack
Base vs side cooling of cylindrical cells is often brought up in online discussions and in many OEMs designing battery packs. We looked at this before within Thermal Conduction in a Cell, however, I think it is worth expanding this topic. The Tesla design cools the side of the cell and the Lucid Motors cools … Read more
Looking at the pouch cell design and edge cooling evolution allows us to appreciated the importance of battery cell electro-thermal behaviour. Fundamentally pouch cells are made from multiple layers of active material all applied to copper and aluminium electrodes that are sandwiched and compressed together. The copper and aluminium electrodes have very good in-plane thermal … Read more
Looking at the benchmarks there are a number of pouch cell cooling options that have been used and threads where we can see improvements to designs. Firstly thought it is worth just reminding ourselves of the heat generation mechanism in a battery cell. Heat Generation in a Cell can be defined quite simple for the … Read more
The TIM application pattern is really important as you want complete coverage between the battery cells and the cooling system. What is TIM? This is Thermal Interface Material and is designed to bridge the gap between surfaces and hence enable a better heat transfer. No surface is perfectly flat and hence the TIM is a … Read more
A cell temperature gradient can limit performance and the lifetime of the cell. Therefore, it is important to design the battery to minimise the temperature gradient. This can be particularly difficult in the case of high performance battery packs. The maximum temperature differential in a cell is normally specified as ~2°C to minimise the degradation … Read more
Dielectric immersion cooling for a battery pack is perhaps the ultimate method of controlling cell temperatures. Dielectric Fluid: an electrically non-conductive liquid that has a very high resistance to electrical breakdown, even at high voltages. The cells are immersed in a dielectric and the dielectric then flows through a heat exchanger to extract the heat. … Read more
Passive cooling means the battery cell or pack is not actively cooled, instead it relies on heat conduction, radiation and convection. This heat transfer will apply in both directions, to and from the environment. Passive cooling should be the starting assumption for all battery pack designs, the drive cycles and user cases could set requirements … Read more
There are a number of temperature limits of a battery cell, some harder limits than others. It is worth understanding these in general before looking at a specific cell. These temperatures will change with chemistry and by cell manufacturer, therefore, it is really important to use the limits as advised by the manufacturer. In addition … Read more
Whatever way we cool a battery cell we will create temperature gradients in the cell. It is not possible to apply cooling to all of the active area of the electrodes, this would be nice, but would significantly reduce the energy density of the overall battery pack. So we have to apply cooling to the … Read more
There are many battery cooling options, which is better or best depends on the cell selection and application. There is no right and wrong. However, let’s look at them and at a first attempt list of advantages and disadvantages. Note: all of the images show a section through cylindrical cells, but each of these cooling … Read more