In a recent tweet, Clement Bommier explained why the two defects GM found on LGES batteries are so severe. According to the Boeing engineer with a Ph.D. in Material Science, the torn anode tab can make the “floating piece of copper” connect the anode and the cathode, which could cause a sustained short circuit.
The folded separator is just as dangerous. The separator’s goal is to separate the cathode and the anode. Depending on how folded it is, it fails in that mission and puts the cathode and the anode in touch.
If it is just folded onto itself, it can make distances between the cathode and anode different. The longer the distance, the lower the current between these spots. That can cause lithium plating that may lead to “electrolyte degradation, and under the right conditions, lead to gas build-up, cell failure, and potential explosion.” Unlike what GM said, any of these defects alone could cause issues to the battery pack.
While the Bolt EV and Bolt EUV owners will have to wait, GM is planning to compensate them with more range. Green Car Reports published a message the company sent to some owners stating the new Bolt EV battery packs will have the latest chemistry available. That means they will get 8% more range and an 8-year or 100,000-mile warranty for the new components.
Although that may be enough to keep some of these customers willing to wait, it is also fair to say GM took quite a while to take action. Some customers affected by the fires would also like to have the company’s attention to compensate for all they have gone through.
The two main causes listed here are:— Clement Bommier (@CBommier) August 24, 2021
1. Torn anode tab
2. Folded separators
These are both serious flaws, and the potential for battery failure. Here's my experience with them, as well as some mitigation ideas a ????https://t.co/ARYyuq6MaD