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
The 2022 Nissan Ariya has two battery pack sizes, 63kWh (66kWh total) and 87kWh (91kWh total). The vehicle is also available in 2WD and 4WD variants. The details around the battery specifications are very scarce and hence lots of gaps we need to gradually fill. However, I think this is worth sharing for the thermal … 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
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 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
Nissan increased the battery capacity from 24kWh to 30kWh with a change in cell supplier. An increase in cell energy and moving from a 4 cell module to an 8 cell module allowed this energy to be contained in the existing case. This meant the overall battery package was the same shape with an ~21kg … Read more
The specific heat capacity of lithium ion cells is a key parameter to understanding the thermal behaviour. From literature we see the specific heat capacity ranges between 800 and 1100 J/kg.K Heat capacity is a measurable physical quantity equal to the ratio of the heat added to an object to the resulting temperature change. Specific … Read more