EVs are a fast-growing market and appear as a promising option against the high emission of gasoline and diesel vehicles. The growth in the EV market has been decent and a regular buyer is still skeptical due to fire incidents occurring with EVs. Complex electronics, improper thermal management, mechanical abuse, improper cell grading activities and control in production, lack of testing in a production plant, and of course, uneven degradation of cells can be one of the reasons this promising technology is facing thermal runaway and in turn, the wrath of the government and public alike.
One of the reasons thermal runaways can be triggered after a cell catches fire is because a part of heat travels via busbars to the neighboring cells, as the busbars can conduct heat faster than the air.
For the heat that is conducted, it is easily understandable that we need to break the electrical, as well as thermal conduction connection to the neighboring cells. This paper presents a comparison of the common cell joining methods- spot welding, and wire bonding and a comparison of them with another non-production method of soldering. A simulation study under different cases has been carried out on a 4p cell model while triggering the thermal runaway in a cell and its effect on the neighboring cells has been studied for the three joining methods mentioned above. A comparison of the three mentioned cases is presented with the temperature of trigger cells and neighboring cells.
It is apparent from the study that soldering appears as the best joining method among all of the methods but industrial methods are not cap as it offers a lower melting point and successfully break the connection earlier during thermal runaway.