Real-time Electromagnetic Characterization of Thermal Runaway Conditions in Li-ion Modules

Parthian Energy is developing a rapid battery diagnosis product, PES [1], which can detect internal short circuits (ISCr) in a few minutes, either during manufacturing or during use. PES works on both cell and module level. It is chemistry and size agnostic, and it works with any battery format. PES may thus enable significantly reduced testing time, and when used during manufacturing, PES can reduce the occurrences of bad cells being shipped with the product. This in turn reduces the number of product returns and the potential for safety incidents. There are several use cases for PES, including during lithium-ion cell manufacturing, starting with cell assembly, which is the earliest time in which a micro-short that has formed in a newly assembled cell can be detected. PES can be placed at any of several points in the cell assembly process, as well as during formation and aging. Since much of the aging step is conducted for detecting micro-shorts, PES can substantially reduce aging time during cell manufacturing. Another use case for PES is up-front cell screening at the start of the pack assembly process. Currently, most pack assembly incorporates some cell screening in order to verify that the Open Circuit Voltage (OCV) of the cell, as well as the Internal Resistance (IR), is in range. PES can be incorporated into this step – either for individual cells or for an array of cells that are configured for the pack. This will allow any cells with micro-shorts to be removed from the pack manufacturing process and disposed of safely, which is very low cost compared to the cost of recall for a failed pack, especially if a micro-short develops into a full short, which can lead to a thermal runaway event or other critical failure. Finally, PES can be incorporated into packs for monitoring cells during use. Fig. 1 below shows an example of how PES can be incorporated into a pack –antennas are strategically placed in or around the pack (similar to cell temperature sensors). A single Printed Circuit Board Assembly (PCBA) with digital and analog circuitry, including the microcontroller with pattern matching software, can be either integrated into the BMS or packaged as a standalone device anywhere on the pack.