from chemistry to pack
AION Engineering INC When engineering a Battery Thermal Management System (BTMS) for electric vehicles or energy storage, one of the most critical factors is hidden within the microscopic architecture of the cell itself. Whether a cell utilizes a wound (jelly roll) or stacked electrode assembly, its physical construction fundamentally dictates its thermal behavior. Heat does … Read more
When we look at the battery pack design for a vehicle we want to minimise the overall weight and hence need the cells to work structurally as part of the pack design. This leads us to Thermally Conductive Adhesives (TCAs) as a means of fixing cells to cooling systems and bonding them into a battery … Read more
What are the options for Thermal Interface Materials (TIM)? What is TIM? This is Thermal Interface Material and is designed to bridge the gap between surfaces and hence enable a better heat transfer. Thermal interface materials (TIMs) can be grouped and broken down in a few different ways, primarily by their product format (how they … Read more
AION Engineering INC Role of Tabs in Current Flow During discharge, the current generated by electrochemical reactions flows through the sequence: Active Material → Conductive Additive → Current Collector → Tab The tab serves as the final current-carrying element in this path. Its current-carrying capacity is therefore a critical factor that affects both electrical efficiency … Read more
The cell to cell temperature gradient in a battery pack will limit the performance and lifetime. However, there will always be a cell temperature gradient and a cell to cell temperature gradient. It is very difficult not to have if we are rejecting or absorbing heat. The cell to cell temperature differences can be due … Read more
Whatever the cell format and however we cool it there will be a temperature gradient. This is described by Fourier’s Law of Conduction. An empirical law stating that the rate of heat flow is directly proportional to the temperature gradient and the area of heat transfer, and inversely proportional to the thickness of the material. … Read more
Cylindrical lithium-ion cells have long used metal tabs to connect the current collectors to the terminals. These tabs act as the path for current to flow out of the electrode layers and into the external circuit. While this design has been reliable for decades, it introduces a few well-known limitations, particularly for high power applications. … Read more
Can we build a quite simple cell busbar thermal model? First thoughts are whether we can make some simple approximations and hence create a spreadsheet model. We have a current [I] flow through the busbar (orange). The busbar has a resistance defined by it’s resistivity, cross-sectional area and length. Hence we can calculate the heating … 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
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