Last month, a Mercedes Benz EQE 350 electric vehicle caught fire A fire broke out in the underground car park of an apartment building in South Korea, leaving 23 people hospitalised and around 900 cars damaged. The blaze reached temperatures of more than 1,500 degrees Celsius and took firefighters almost eight hours to extinguish it.
The incident gave rise to a series of rapid policy changes in the country, including the acceleration The electric vehicle battery certification program and new rules in Seoul that should prevent owners from “overcharging” their vehicles in underground parking lots have also forced automakers to do something they normally wouldn’t do: reveal which makes the batteries for its electric cars. (In early September, the South Korean government said that require (Automakers are required to disclose this often secret information.)
Data from the National Transportation Safety Board, the US’s independent federal research agency, shows that the fire risks from electric vehicle batteries are low. Very low, in fact. An analysis of that data by an insurance company He suggested that more than 1,500 gasoline cars catch fire for every 100,000 sales, compared with just 25 electric vehicles.
In a sense, fire is a risk in any kind of battery technology. Professionals talk about the “fire triangle,” the three-ingredient recipe for ignition. Fire needs oxygen, a spark and fuel. Since the whole point of a lithium-ion electric vehicle is to store energy, the fuel is always there. EV batteries are designed to be compact and isolated from other parts of the vehicle, but an incident like a catastrophic crash could quickly introduce oxygen and heat into the brew.
Building a fireproof battery
Some battery makers have taken steps to reduce the risk of their batteries catching fire. The first is to create strict manufacturing processes and standards. This is important because any kind of defect in a battery could lead to a fire, says Venkat Srinivasan, who studies batteries and heads the Argonne Collaborative Center for Energy Storage Science at Argonne National Laboratory in the US.
To understand why battery manufacturing matters for fire risk, you have to understand the basics of lithium-ion batteries. The anode and cathode of the battery store lithium and are connected by an electrolyte, a liquid chemical that passes lithium ions between them to store or release energy. If, for example, a tiny metal particle gets into that electrolyte through a dirty manufacturing process and continues to become electrified as the battery charges and discharges, it could create a spark, crack open the battery cell and allow oxygen in and possibly expose the entire battery to fire.
These kinds of problems with battery manufacturing do happen. In August, Jaguar told some 3,000 owners of its 2019 I-Pace SUV parked their vehicles outside due to fire risk, which was linked to three fires. The manufacturer behind the packages in those vehicles, South Korean firm LG Energy Solution, has been the subject of a US Road Safety Research from 2022. BMW, General Motors, Hyundai, Stellantisand Volkswagen All vehicles have been recalled for battery risks (some of them in hybrid rather than fully electric vehicles). But such situations are rare. Through robust manufacturing processes, “you can never make the risk of fire absolutely zero, but good companies have minimised the risk,” says Srinivasan.
Less burning chemicals
The good news is that batteries in cars that are less likely to catch fire are now available, thanks to a specific chemical composition that is harder to ignite. Since the first Tesla hit the road in 2008, the standard battery in electric vehicles has been made primarily from nickel and cobalt. Batteries with this composition charge quickly and retain a lot of energy, which is great for EV use because drivers of vehicles using them enjoy longer ranges and faster recharges. They are also more likely to go into “thermal runaway” at lower temperatures, in the range of 400 to 300 degrees Fahrenheit (210 to 150 degrees Celsius).
Thermal runaway is a state in which lithium-ion batteries enter a kind of fatal fire loop: a damaged battery cell produces heat and flammable gases, which in turn produces more heat and flammable gases, which begin to heat up nearby battery cells, which release more heat and gas. The fire then becomes self-sustaining and difficult to extinguish.
