The Chevy Bolt Recall & The EV Battery Fire Problem

A while ago, GM started telling customers of its Chevrolet Bolt not to use them. This is due to a series of

battery

-related

fire

s that led to three

recall

s and cost GM 1.8 billion in warranty costs. GM is looking to pass those costs on to its

battery

. Power solution provider LG, sometimes also known as LG Chem, of which it is a recent spin-off, LG has acknowledged its responsibility in the entire situation, attributing it to a cell manufacturing quality issue, lawsuits will likely be filed in the future. This brouhaha illustrates an ongoing concern with the latter. high energy electric vehicle battery

fire

generation in this video we are going to take a look at these high profile electric vehicle events and what they mean for the industry for this video i want to give my sincere thanks and appreciation to an anonymous viewer and good friend of the channel for his thoughts and technical guidance.

EV batteries are a complicated thing and I'd hate to be calling out any mistakes that are mine, of course, okay, first let me talk about the asymmetry bulletin. If you subscribe to the channel, you should do so too. subscribe to the newsletter read full scripts from older videos with additional commentary after the fact, there are also exclusive newsletters like a recent one in the Maldives. You can find the link to the newsletter in the video description below or you can just go to arbitrary Asian. dot com from now on you can expect a new newsletter every Thursday at 1am Taiwan time.

Okay, let's get back to the show. The 2017 Chevy Bolt made by GM has a 60-kilowatt-hour, 350-volt lithium-ion battery. The 2020 version had an improved version. At 66 kilowatt hours, the pack is made of 288 lithium-ion cells in 96 modules, three cells in parallel, and has an expected range of about 200 miles on the highway. These are pouch type cells, their main chemistry is composed of lithium oxide, nickel, cobalt oxide and lithium. magnesium oxide, this nickel-rich architecture allows the car to go further and accounts for one-fifth of the car's total cost. The first

recall

was issued in 2018. In November 2020, the company issued a software update that attempted to fix the issue, but a few more.

Fires broke out with one of the

bolt

s that had the updated software, leading to a second recall in July 2021 and now this latest one, a month later, this August 2021 recall is the largest yet and covers Chevy

bolt

s from model years 2020 to 2022. In addition to some 2019 models that had not been covered in previous recalls, it basically remembers every one of the 141,000 bolts sold. GM has advised Bolt owners to do the following: Park 50 feet away from other cars, park on top. parking lot floor monitor your car while charging, only charge the battery to 90 percent, do not discharge within 70 miles and always park the vehicle outside the

chevy

bolt recalls are a bitter pill to swallow for GM, considering that Bloomberg reported in 2016 that the company was expected to take a loss of between $8,000 and $9,000 for each vehicle sold, regardless of whether GM replaced the batteries.

Working with LG to increase production of replacement battery modules. The two companies are so closely linked now that they have no choice but to work together through this divorce. This divorce is not an option. When an electric vehicle battery catches fire, it tends to make the news, especially if that car is a Tesla. that always gets clicks. This is due to two reasons, the first is that the battery of the electric vehicle is discharged. They are rare if stored and operated within the limits recommended by the manufacturer. A lithium-ion battery has a failure rate of 1 in 40 million.

Elon Fang makes it clear that fires are much more common in the internal combustion of automobiles and Battery fires tend to make the news because they are relatively rare, it is difficult to find exact comparable statistics, but in 2019 there were 190,000 conventional vehicle fires in the United States, as Dogenus points out, of course, the statistic is partly due to the fact that EVs themselves make up a relative minority of the overall car population, but there is some auto insurance data that shows that EVs tend to have a lower fire rate and of course that's also It is necessary to counter that electric vehicle owners tend to be richer and, therefore, possibly better off. or more careful drivers, hence the lower car fire rate, as Twain says there are lies, damn lies and statistics such and such, the second big reason these EV fires tend to make the news However, it is in fact very much related to safety, it is because, as I hinted above, these fires tend to burn big and hot to know why this is the case, we need to look inside the battery.

If you remember, batteries always have a series of comical components: the anode, the cathode electrolyte and the separator, during normal operations the lithium ions move from the anode to the cathode and this drives the machine in recent years. Customers have come to expect more from their electronic components, for example, more range and faster charging times for their electric vehicles. To meet this demand, the market has developed and introduced new chemistries, especially in the cathode space, including nickel. -manganese-rich materials and a bunch of other things that look like they belong in a science fiction novel The makers of vanadium pentoxide or carbon-coated lithium iron phosphate nanospheres are walking on a bouncing rope, and adding more of these materials can increase the length of time the battery can discharge power or how much power it can discharge, but doing so can also lead to thermal instability and really bad fires.

If the battery becomes too hot, is damaged for any reason, or has manufacturing defects, there are fire risks it can cause. what is euphemistically called within the industry is thermal track batteries catching fire for various reasons for this specific scenario. I would talk about a temperature induced one when things are working normally, the battery cells generate heat, but that heat is relatively low and dissipated safely. Outside the module, the internal structure of the battery remains solid, but as the temperature increases and continues to increase beyond certain thresholds, the battery components begin to chemically transform and, if there is nothing to stop this, it can lead to a thermal track.

Either the solid electrolyte interface layer or the SEI, the SEI layer is formed on the anode as part of the electrochemical manufacturing process. This waterproof layer protects the anode from reacting with electrolyte molecules. I mentioned this in my video on making electric vehicle batteries. You can get more information. about the whole process in that anyway, when the temperature gets too high, usually around the 90 to 120 degree centigrade level, the sei breaks down, this generates additional heat and creates carbon dioxide in the process, the chain reaction now can continue without the sei layer. electrolyte barbarians can break the gates and react with the anode, this generates even more heat as electrolyte reactions tend to be especially hot with temperatures above 135 degrees Celsius the separator loses its structural integrity the separator is a safety measure important inside the The battery with the separator that no longer separates the anode and the cathode come into contact and causes what is called an internal short circuit.

An internal short circuit is the most common reason why an Eevee battery starts to catch fire. At this point, the battery begins to self-ignite. -discharge the cathode and anode begin to break down releasing oxygen and even more heat. Different cathode chemistries are more vulnerable to this breakdown than others. Lithium and cobalt oxides are probably the most vulnerable, so lithium iron phosphates are probably the least vulnerable and therefore tend to be the safest, but with different drawbacks of their own when the temperature exceeds the 200 degrees Celsius, the electrolyte also decomposes releasing its own heat critically. Decomposition releases reactive and potentially explosive gases such as carbon dioxide, hydrocarbons and fluorinated gases.

By now every part of the battery is breaking down and the car. It is likely that a fire is burning that is exceptionally difficult to put out Electric vehicle fires are not your typical backyard car fires, if such a thing exists because they are caused in part by direct reactions between battery components, it is possible that do not require external oxygen, therefore firefighters generally find them more difficult. To extinguish conventional vehicle fires, one example in the city of Fort Lauderdale in the United States required between seven hundred fifty and one thousand one hundred liters of water, in some cases They may require more than ten thousand liters of water and more than sixty minutes to put it out.

In an Eevee fire, this is substantially longer than the five minutes of a conventional car fire. Firefighters tend to use water to extinguish a fire, but this can create additional risks. The salt in the electrolyte, called lithium hexafluorophosphate, can react with water to create hydrogen fluoride. In the petrochemical industry, a corrosive gas, hydrogen fluoride, is used to create superacids. Enough has been said, and water poured into the battery can cause additional short circuits. Dirty water seeping into the bowels of the battery is known to cause fires. There have been some eevee. Additionally, bus incidents in China with such EV batteries tend to reignite long after the fire has apparently been extinguished.

This is due to residual energy within the battery, for example the battery in the Fort Lauderdale Carr fire reignited while the burned vehicle was being towed. From the accident scene, the fire was quickly extinguished, but then reignited again once it reached the salvage yard, another fire in southern Jordan, USA, also reignited on the same day of the accident and then again five days later, considering that a fire broke out in the vehicle's battery. It is not an ordinary fire, manufacturers have taken great measures to install systems that prevent them from occurring. There are a variety of reasons why battery fires can start, sometimes they never find the reason, so manufacturers have designed a variety of safety measures to prevent thermal runaway. start or get out of control some measures are obvious others require balance compensations, for example, expanding the space between cells in modules.

Tests in the laboratory found that if one cell is compromised, it can heat its neighbors and cause chaining. For this reason, manufacturers sometimes add literal firewalls between the cells, but doing something like this reduces the energy density and reduces the vehicle's range. Customers may be less willing to buy such a car, so battery management systems within the modules are also compensated. Critical separation of a module and its electrical systems can prevent a full thermal runway event, and since modules are the nervous system of the pac, software can be incorporated to predict the sellability of a thermal runway based on levels. load and temperature changes, the latter due to abrupt variations in heat. are as dangerous as the absolute level of heat to the cells themselves, the manufacturers themselves have identified that the separator has a critical safety measure to prevent thermal runaway.

The reason why the separator is mainly made of polymer is that when it gets too hot, the pores of the polymer close a process called separator shutdown, this prevents the cathodes and anodes from meeting and prevents an internal short circuit from occurring. The reactions will stop and, as long as the separator maintains its structural integrity, the battery can begin to calm down. Engineers have implemented triple layer and ceramic separators. Hybrids of coated polymers that maintain their stability even in difficult temperatures. However, it is important to remember that each element has its limit and to prevent thermal track gases from causing potential explosions, cells can be manufactured with fail-safe venting mechanisms, a variety of options are guaranteed.

Patents for them, cylindrical 18650 batteries can have small ventilation windows, pressure-sensitive caps, or simple sealed holes. This is in no way acomprehensive review of EV battery safety mechanisms. I've literally only scratched the surface, but it gives you an idea of ​​how big it is. The deal is on the minds of the manufacturers and despite everything things can still go wrong, there is no doubt that this recall is a success for LG Energy. The company prides itself on its advanced chemistries and industry-standard bag designs for its battery cells, whether they are in stock or not. There could be something fundamentally wrong with LG's bag design, as Elon seems to imply in a tweet that's harder to say.

The issue that is more interesting to consider is whether the real or perceived safety risks with these nickel-rich battery chemistries will affect automakers. When opting for lithium iron phosphate batteries, as I briefly mentioned, these chemistries tend to be safer when it comes to thermal tracks, but they do have drawbacks in the form of energy density and weight. Companies like byd and kadl dominate the lithium iron phosphate world in terms of production and patents, they are doing some really interesting things with cell to pack that try to improve the aforementioned drawbacks. Tesla's use of lithium iron phosphate in some of its Chinese Model 3s could be an indication that these chemistries are becoming good enough, with Chinese players likely to gain share in areas like Norway where autonomy is a minor concern for the industry as a whole.

The push for electric vehicles is too strong right now. GM has committed to launching a whole series of electric cars in the future. Companies like Ford and Porsche. are making electric versions of their flagship cars, a few bumps in the road are a price we're willing to pay for a greener future, that being said, never overcharge your EVs, folks, okay, that's it for this one. evening, thanks for watching, if you enjoyed the video, consider subscribing. the newsletter or follow the twitter want to email me write to me at john asian arbitrary dot com I love reading your emails introduce yourself suggest a topic or more until next time I'll see you later