from chemistry to pack
How does the choice of cell format influence battery pack mass? The three main cell formats: Cylindrical, Prismatic and Pouch. There are pro’s and con’s with each. One of the most significant differences is the amount of mechanical support required. The pouch cell needs the most support and fixing, followed by the prismatic and the … Read more
The BYD FC4680P cell is a Lithium Iron Phosphate chemistry in the Tesla 4680 cell format. 4680 => 46mm in diameter and 80mm high A small plug in the top is described as an “explosion proof valve”. Independently measured values shown in bold Key features Dimensions Safety Data Data as shown on manufacturers specification sheet. … Read more
Recent industrial and academic studies have shown that aluminium cell housings can provide several benefits in terms of thermal management and gravimetric energy density in particular1,2,3. However, as Cell-To-Pack and Cell-To-Chassis approaches arise the battery cell and therefore, the battery cell housing, become part of the structure of the battery electric vehicle contributing with their … Read more
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
A 4680 cell concept The battery industry is targeting larger cell formats, which enable simplified module design and cell-to-pack or even cell-to-chassis solutions. In this regard, hard case battery cells and in particular cylindrical cells will play an important role in enabling the named developments. Tesla’s announcement of a tabless 4680 cylindrical LIB has triggered … Read more
Cylindrical Cell Electrode Estimation: An alternative geometric approach. Here we present a simple method for estimating electrode length in a cylindrical cell. The method is equally applicable to other formats since we make an estimation of the total active electrode area. Results require knowledge of one electrode Active Material (AM) chemistry, electrode porosity and thickness … Read more
Using some simple mathematics and dimensions we can do some cylindrical cell electrode estimation. Knowing the outer and inner diameter of the spiral along with it’s thickness we can calculate the length of the material to create it. D is the inner diameter of the cylindrical can. The inner diameter is that of the mandrel … Read more
In this Article, we will compare different Cylindrical Cell Sizes used in electric Vehicles. 4680 vs 21700 vs 18650.
Caution: This is a very difficult pack to reconcile the numbers around at the moment and so we are continually updating our calculations and estimates. We will get there, but it might take some time. Specifications: Assuming the 4680 cell from the Munro teardown is correct at 23.35Ah then we have the following parameters: Assuming … 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