With the push to transition people worldwide from traditional combustion-powered vehicles to electric vehicles, development is happening very quickly for electric vehicles. However, there are some hazards and downsides to electric vehicles that don’t come with traditional combustion vehicles. Specifically, in the event of an accident, there’s always a risk of fire due to punctured battery packs in an electric vehicle.
As we’ve learned over many years and with many instances of defective batteries, sometimes battery fires happen even without damage to the battery pack. GM has found this out the hard way with a rash of fires in its Chevrolet Bolt EV range that have destroyed vehicles and property. GM announced not long ago that some owners would get new battery packs under a recall. Shortly after that, it announced a significantly expanded recall covering every Bolt EV ever produced. An expert is now pointing to a surprising source as a potential reason for battery fires.
The automaker has traced a potential source for the battery fires to two issues that occurred simultaneously in the LG Chem battery packs used in the vehicle. Initially, the problem was discovered in battery packs produced by one of the battery manufacturer’s facilities. As a result, vehicles that had those battery packs inside were recalled last year. However, fires continued spurring additional investigation. GM then traced the issue to torn anode tab and a folded separator inside some battery packs.
The issue has been described as a “perfect storm” in the pouch-type battery cells used inside the battery packs, which are layers of cathodes, anodes, and separators in a liquid electrolyte encased in a flexible polymer pouch. Typically that creates a flat battery, but a torn anode tab would make the anode closer to the cathode. According to one expert, that defect alone wouldn’t have likely caused fires, but compounding the problem was that the battery packs also had folded separators.
With the separators not in their correct location, the anode and cathode could bridge the gap, creating a short possibly leading to a fire. According to the expert, the torn anode tab and folded separators are likely in the same area, indicating some sort of robot misalignment in manufacturing. GM and LG have reportedly identified the problem, and the identification is what prompted the massive recall of vehicles.