  Unless you’ve been living under a rock, you already know that electric vehicles (EVs) are becoming increasingly popular as people look for more sustainable and affordable transportation options. However, as with any new technology, there are certain risks associated with their use. One of the most significant concerns related to EVs is the potential for fires and the difficulties in extinguishing them. The industry is changing rapidly, and what was true just a few years ago has already changed. It's essential for people to be aware of how to reduce the risk of fire, what to do in case of a fire, and what the future holds for this technology and the concern with vehicle fires. Given the vastness of the topic, we have decided to present a three-part series on EV battery fires. The first part will examine what causes them, the second will focus on innovations in the industry to address concerns and improve battery safety, and the final part will look at the future fire risks of electric vehicles, and how we predict the technology will change. Our goal is to clarify misinformation and provide accurate and comprehensive knowledge of the issue to our readers. So, without further ado, let's get right to it!
What causes a fire in an EV battery? There are several reasons that can cause a fire in an EV, but the majority of cases are due to a fault or defect in the battery design, abuse of one or more battery cells (by overheating, crushing, penetration, or overcharging), or as a result of a collision. A fire starts when a damaged or abused battery cell is short-circuited, triggering a chemical reaction that generates toxic and flammable gases, and a significant amount of heat. This heat can lead to a chain reaction called “thermal runaway”. Hot Thermal Runaway works: Electric vehicle battery packs are typically composed of hundreds, if not thousands, of individual battery cells that are densely packed together to occupy as little space as possible. When one or more of the battery cells are damaged or abused, the resulting heat can affect the battery cells adjacent to the first, causing a failure, more heat, and gases in an uncontrollable exothermic chain reaction. As thermal runaway progresses, the separator structure within the battery cell collapses, causing the electrodes to touch. This creates an internal short circuit that generates even more heat. Eventually, the pressure builds up and the gases within the cell are vented, either through blast caps in cylindrical and prismatic cells or by the bursting of pouch cells. During this process, heavy metal dust particles from the cathode can form a dark cloud, which is followed by a white vapor cloud as the gases carry fine droplets of the solvent. As oxygen mixes with the vapor cloud & heat continues to build, the battery cell may ignite, causing surrounding cells to do the same. In rare cases, the vapor cloud can explode without warning. Luckily, this is unlikely to occur. Roughly 11% of the cases that have been reported to Australian research company, EVFireSafe, described a vapor–cloud explosion. How often do EVs catch fire compared to other vehicles?
It is important to note that while fires in electric vehicles are much less common, the biggest risk is when fires happen. In ICE vehicles, fires usually occur during operation of the vehicle and this results in little damage to external property or life as the vehicle is located in an area away from buildings and people. However in an electric vehicle, the fires that do occur are often while the vehicle is parked and charging. This means that damage and destruction of other nearby vehicles or the physical structure (garage, house, parking facility) can occur. In some cases, owners houses have been completely destroyed as a result of a fire starting while they were sleeping. What makes EV fires different from other vehicles? In ICE vehicles, fires are most commonly caused by fuel leaks, electrical system failures, or overheated engines. Naturally, EVs don’t have to worry about most of those causes, but EVs are drastically different from ICE vehicles once a fire is already present. In an ICE vehicle, starving the fire of oxygen will usually extinguish it. However with an electric vehicle, this will not work. That is because most battery cells already contain everything needed to sustain a fire, no outside material or oxygen is needed. The cathode of the battery cell often provides a source of oxygen, and commonly used battery chemicals are highly flammable, even at room temperature. This means that even if you submerge a burning battery cell, it will continue to have a thermal event until the temperature of the cell is reduced significantly. Additionally, the location of EV battery packs (often located under passenger compartment) make accessing the source of the fire very difficult for emergency responders. If a battery cell goes into thermal runaway, this positioning makes it very difficult to direct a stream of water onto the battery pack to cool it. EV fire suppression Eventually, an EV on fire will burn out completely on its own. In some cases though this could take a very long time and secondary ignition is a risk (we’ll get to this more later). The most common method currently used on EV fires is to apply large amounts of water to the vehicle for an extended period of time. This has the effect of cooling the battery cells and bringing them out of a thermal runaway event. This method requires emergency responders to spend hours, and many tens of thousands of gallons, to get the fire under control so that the scene can be cleared. Other methods are to jack one side of the vehicle up to allow better access to the battery pack (not recommended by some manufacturers), and a third common method is to submerge the vehicle entirely in a large container of water. All three of these methods are used to cool the battery pack. Once again, there is no way to starve the fire of oxygen. Secondary ignition Secondary ignition, also known as re-ignition, occurs when nearby battery cells that were damaged in the initial incident or even cells in other modules go into thermal runaway and ignite after a battery cell has already caught fire and been suppressed. Although the original cell does not typically reignite, other cells can ignite at different times, leading to reignition of the EV traction battery. This can happen without warning and in some reports happened more than two months after the initial event. Naturally, this can pose a significant risk if proper precautions were not taken to protect surrounding property. According to some fire agencies around the world, the best practice is to allow the EV traction battery to burn out completely while protecting the surroundings. However, this may not be practical in many cities and towns where road closures and long firefighting operations may not be feasible. In these cases, monitoring the battery for a period of time (15-30 minutes) using thermal imaging cameras and listening for audible signs of thermal runaway, such as popping or hissing noises, is suggested before clearing the vehicle for towing.
While EV fires are different from ICE vehicles and require different methods of suppression, they are also incredibly rare. Nonetheless, there is still room for improvement and innovation to make EV batteries even safer.
In the upcoming articles in this series, we will explore various topics such as making safe EV batteries, the role of Battery Management Systems (BMS) in preventing fires, how battery state of charge affects fire risks, and technology being designed and implemented to reduce the risk of battery fires. We will also discuss fireproof EV battery pack designs and what we can expect in the future. Stay tuned for more information on how the industry is working to make EVs even safer!
Ted Miller, Manager, Ford Battery Cell Research and Advanced Engineering. Credit: Ford Motor Co.
Ford revealed its plans recently to invest $3.5 billion in constructing the first-ever automaker-supported lithium iron phosphate (LFP) battery factory in the country. This move will give customers access to a new battery chemistry option for Ford's EV lineup, adding to the current lithium-ion battery technology.
They're calling it BlueOval Battery Park Michigan - that's where 2,500 people will get to work in 2026 producing LFP batteries for Ford's electric vehicles - and it is the first of it's kind here in the US. While other automakers use the LFP battery chemistry in their electric vehicles, Ford will be the first to own it's own LFP factory here in the country and it's only a small part of the commitment the company is making to the electric revolution. Ford and its battery tech partners have committed to investing in electric vehicle and battery production in the US. And since 2019 - with this latest $3.5 billion investment included - the total commitment comes to $17.6 billion. This investment is part of Ford's larger plan to invest over $50 billion in electric vehicles globally by 2026. The investments made in the next three years will create over 18,000 direct jobs in Michigan, Kentucky, Tennessee, Ohio, and Missouri, and over 100,000 indirect jobs, according to an independent study conducted in 2020. These investments mark a significant step towards creating a more sustainable future and increasing job opportunities here in the US. “We are committed to leading the electric vehicle revolution in America, and that means investing in the technology and jobs that will keep us on the cutting edge of this global transformation in our industry,” said Bill Ford, Ford executive chair. “I am also proud that we chose our home state of Michigan for this critical battery production hub.” By diversifying and localizing its battery supply chain in the countries where it produces EVs, Ford aims to make its vehicles more accessible and affordable for customers, while also strengthening consumer demand. As part of its Ford+ plan, the company is striving to achieve an annual production rate of 600,000 electric vehicles worldwide by the end of 2023 and 2 million globally by the end of 2026. As Ford ramps up its electric vehicle production, the introduction of LFP batteries will enable the company to produce a higher number of electric vehicles and provide a wider range of options to new EV customers.
By offering LFP batteries as an alternative to nickel cobalt manganese (NCM) batteries, Ford is providing its customers with the flexibility to choose the battery chemistry that best fits their specific needs. LFP batteries are known for their durability and ability to handle frequent and fast charging, all while utilizing fewer high-demand, high-cost materials.
This cost-effective battery, produced at scale, will assist Ford in maintaining or even lowering the prices of its electric vehicles, making them more affordable for customers. Ford plans to use these LFP batteries to power a range of next-generation EV passenger vehicles and trucks currently in development, with most being produced in the US. “Ford’s electric vehicle lineup has generated huge demand. To get as many Ford EVs to customers as possible, we’re the first automaker to commit to build both NCM and LFP batteries in the United States,” said Jim Farley, Ford president and CEO. “We’re delivering on our commitments as we scale LFP and NCM batteries and thousands, and soon millions, of customers will begin to reap the benefits of Ford EVs with cutting-edge, durable battery technologies that are growing more affordable over time.” 
Ford will soon offer two battery chemistries for electric vehicles. Credit: Ford Motor Co.
As a means to increase production capacity and reduce wait times for customers, Ford plans to introduce LFP batteries on the Mustang Mach-E this year and on the F-150 Lightning in 2024, even before the new battery plant becomes operational.
As a part of its strategy, Ford has forged a new agreement with Contemporary Amperex Technology Co., Limited (CATL) – the world's leading battery manufacturer. The agreement will allow Ford's wholly owned subsidiary to manufacture battery cells using LFP battery cell expertise and services provided by CATL. These LFP battery cells will be integrated by Ford engineers into its electric vehicles, as the company looks to expand its battery capacity and technology through various key collaborations. This agreement with CATL adds to Ford's existing battery capacity and technology, which has been made possible through collaborations with LG Energy Solution (LGES) and SK On. Through these partnerships, Ford is well-positioned to enhance its electric vehicle offerings and establish itself as a significant player in the expanding electric vehicle market.
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