Runaway EV Battery Fire Issues Could Soon Be Extinguished By New Tech
The only thing stopping LG Chem from implementing it now is scaling, but that might only be a temporary delay.
Thermal runaway that could lead to a rare but dangerous EV battery pack fire is not only a scary concept, but it's also the sort of fire that's incredibly difficult to put out as each battery cell begins to cascade towards failure and feed more fuel into the fire itself. Right now, there is no direct solution to prevent this cell runaway phenomenon and the only solution to stop an EV fire is to douse the vehicle in hundreds or thousands of gallons of water. We say “right now” because LG Chem appears to have found a rather simple solution to the threat of runaway EV fires: a thermal fuse, of sorts.
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As it published in Nature Communications—a scientific journal—LG Chem claims it has created a “temperature-responsive material” that’s 1/100th the diameter of an average human hair. This means the material is thin enough to be placed between the cathode layer (the “ground” or negative side) and the current collector (the part that creates the anode or the positive side) of the battery cell without removing any significant amount of energy density. A reduction in energy density has been a major issue with using any sort of internal extinguisher along with reaction time of the suppressant. Considering that thermal runaway is a rare event, the benefits of an internal suppressant were outweighed by the reduction of energy density these safety devices have. With LG Chems thermal “fuse,” that excuse will now hopefully go out the window.
At the early stages of thermal runaway, this material acts as a fuse of sorts and will either stop or significantly reduce the temperature increase by preventing the battery from shorting within itself. The material does this not by suddenly blowing open like a fuse you’re used to, but instead the rise in temperature causes the material to become more resistive to electricity. According to the study, for every 33 to 34 degrees in temperature rise, the material gains up to 5 kilohms of energy resistance. It can also reverse the process and decrease resistance by the same amount of heat reduction. This resistance is also enough to block the reaction path between anode and cathode during this early stage of thermal runaway.
Testing was performed with a Lithium Cobalt Oxide and Nickel Cobalt Manganese (NCM) battery packs. It showed that this material works when the battery pack is impacted or punctured and, when it doesn’t fully prevent a battery fire, it acts as a suppression material—the material doesn’t ignite—and allows the flames to be extinguished shortly after appearing and preventing further thermal damage and fire. Specifically, for NCM battery testing, a 22-pound weight was dropped on both packs with and without LG Chem’s thermal fuse. All batteries without the thermal fuse caught fire, according to the study. For the batteries with the thermal fuse, 70 percent did not ignite while 30 percent did flame up but were extinguished within seconds.
