Last month, a A Mercedes Benz EQE 350 electric vehicle caught fire in the underground parking garage of an apartment building in South Korea. 23 people were reportedly sent to hospital and approximately 900 cars were damaged. The fire reached temperatures of more than 2,700 degrees Fahrenheit (1,500 degrees Celsius) and took firefighters nearly eight hours to extinguish.
The incident prompted a series of rapid policy changes in the country, including speeding up a planned certification program for electric car batteries and new rules in Seoul that are supposed to prevent owners from “recharging” their vehicles in underground parking lots. It also prompted automakers to do something they wouldn’t normally do: disclose who makes the batteries in their electric cars. (In early September, the South Korean government said it would require automakers to disclose this often secret information.)
Data from the National Transportation Safety Board, the independent US federal investigative agency, show that the risks of electric vehicle battery fires are low. Very low actually. An analysis of this data by one insurance company suggests that more than 1,500 gas-powered cars are ignited per 100,000 sales, compared to just 25 electric vehicles.
At some level, fire is a risk with any kind of battery technology. Professionals talk about the “fire triangle” – the three-ingredient recipe for ignition. Fire needs oxygen, spark and fuel. Since the purpose of a lithium-ion electric vehicle is to store energy, the fuel is always there. EV batteries are meant to be tightly packed and isolated from the rest of the vehicle, but an incident like a catastrophic crash can quickly introduce oxygen and heat into the drink.
Construction of a fireproof battery
Some battery manufacturers have taken steps to reduce the risk of their batteries catching fire. The first is to establish strict production processes and standards. That’s important because any kind of defect in a battery can lead to hell, says Venkat Srinivasan, who studies batteries and directs the Argonne Collaborative Center for Energy Storage Science at the US Argonne National Laboratory.
To understand why battery manufacturing matters for fire risk, you need to understand the basics of lithium-ion batteries. A battery’s anode and cathode store lithium and are connected by an electrolyte, a liquid chemical that passes lithium ions between the two to store or release energy. If, say, a small particle of metal gets into this electrolyte through an impure manufacturing process and it continues to electrify as the battery charges up and down, it can create a spark, open the battery cell and allow oxygen to flood in and possibly exposing the entire battery pack to fire.
Such blunders in battery manufacturing do happen. In August, Jaguar told about 3,000 owners of its 2019 I-Pace SUV to park their cars outside because of a fire risk, which was linked to three fires. The manufacturer behind the packages of these vehicles, South Korean firm LG Energy Solution, is subject to a US road safety inspection from 2022. this way. BMW, General Motors, Hyundai, Stellantis and Volkswagen have recalled vehicles due to battery risks (some of them in hybrid, not all-electric vehicles). But these situations are rare. Through sound manufacturing processes, “you can never make the risk of fire absolutely zero, but good companies have minimized the risk,” says Srinivasan.
Fewer fire fighting chemicals
The good news is that less flammable batteries are now rolling into cars, thanks to specific battery chemicals that are harder to ignite. Since the first Tesla hit the road in 2008, the standard battery for electric vehicles has been made mostly of nickel and cobalt. Batteries with this makeup charge quickly and hold a lot of power, which is great for EV use, as drivers of vehicles that use them enjoy longer range and faster charging. They are also more likely to enter a “thermal run” at lower temperatures, in the 400 to 300 degrees Fahrenheit (210 to 150 degrees Celsius) range.
Thermal runaway is a condition in which lithium-ion batteries enter a kind of fiery chain reaction: A damaged battery cell produces heat and flammable gases, which in turn produces more heat and flammable gases, which begins to heat up nearby battery cells, which release more heat and gas. Then the fire becomes self-sustaining and difficult to put out.
