Electric Vehicles Aren’t Ready for Extreme Heat and Cold. Here’s How to Fix Them

Such updates aim to remove major obstacles to the promised electric vehicle revolution. The Biden administration is working on increase in electric vehicle ownership in an ambitious bid to reduce greenhouse gas emissions, and the president hopes electric vehicles will make up half of all new vehicles sold in the US by 2030 (compared to approximately 8 percent car sales in the first half of 2023). But recent failures, such as the Chicago car shutdown, show how current electric vehicle technology could fail as future weather conditions become even more extreme: Climate change continues drive up average global temperatures, but this breaks the patterns that have long governed the planet's weather, so overall warming could lead to worsening cold snap.

“Extreme cold poses a safety risk when charging batteries,” says Paul Gasper, a scientist in the electrochemical energy storage group at the National Renewable Energy Laboratory. Scientists generally consider lithium-ion batteries to be safe for use in relatively narrow temperature range is 32 to 140 degrees Fahrenheit (zero to 60 degrees Celsius), but estimates vary. When temperatures outside reach 20 degrees Fahrenheit (minus seven degrees Celsius), the average EV range drops 12 percent compared to the range at 75 degrees Fahrenheit (24 degrees Celsius), the American Automobile Association reports. found in 2019. To understand why, we need to dive into the chemistry that powers an electric car battery.

About supporting science journalism

If you enjoyed this article, please consider supporting our award-winning journalism. subscription. By purchasing a subscription, you help ensure a future of influential stories about the discoveries and ideas shaping our world today.

Temperature check

When electric vehicle batteries are discharged, the lithium ions that carry the charge travel through liquid electrolyte from one end of each battery cell to the other (between the positive cathode and negative anode). Then – as cars drain the battery's stored energy while driving – the ions return in the opposite direction. If the battery cools (for example, during a cold snap), the liquid line between the anode and cathode thickens, slowing down the movement of ions. This means that cooler batteries may take longer to charge and may lose their charge sooner than in more moderate temperatures.

Charging vehicles at temperatures below 32 degrees Fahrenheit can produce lithium ions. accumulate on the surface of the anode because the particles cannot move fast enough. These ion clusters, called electroplating, can cause the battery to short-circuit and even spark explosion. (Still, electric cars are catching fire relatively rare compared to gasoline-powered cars, and researchers are studying designs for batteries that die on their own.)

On top of that, the entire EV works overtime to warm up the car. Its thermal regulation system, which regulates The temperature of the battery, electric motor and other components also drains the charge. And when the driver turns on the interior heat, the battery must power the HVAC system and other devices such as the seat heater and defroster. Gas vehicles with internal combustion engines also suffer from the cold; their fuel economy drops by about 15 percent at 20 degrees Fahrenheit compared to what they would get at 77 degrees Fahrenheit (25 degrees Celsius), in accordance with US Department of Energy. But the equivalent loss for an electric car can be staggering 39 percent at 20 degrees F.

Extremely hot days can also harm EV performance. Higher temperatures speed up the movement of ions, and at some point this triggers a cascade of unintended chemical reactions that can lead to the breakdown of battery components, including the electrolyte, over the life of the vehicle. When outside temperatures reach 95 degrees F (35 degrees C) and drivers turn on the air conditioning, range may be reduced. decline by 17 percent, the AAA report said.

AI settings

Working with automotive software will allow you to better take advantage of the batteries that are already on the market. Tesla and other electric vehicles with sophisticated on-board computers use sophisticated artificial intelligence models to ensure safe and efficient battery operation; these artificial intelligence programs analyze data from temperature and voltage sensors to prevent the battery from overcharging and predict how far the car can travel on its remaining charge. Tesla also has a feature called preliminary preparationin which vehicles heat or cool the battery to the desired charging temperature. But these models need some improvements, Gasper says.

First, they could be better tuned to take into account the condition of the battery as it deteriorates over time, he explains. He also believes AI models can help cars succeed in a wider range of temperatures (by distributing coolant or controlling fans, for example) without putting the car or driver at risk. As these models improve, we could better trust electric vehicles to safely manage the battery “over the widest operating window possible,” Gasper says.

For now, AI models can only give drivers a rough idea of ​​the current charge level and health of the battery, says electrical engineer I. Safak Bayram, an associate professor at the University of Strathclyde in Scotland. That's why EV drivers often see their car's range estimates plummet, he adds. There was only one Uber driver left in Chicago in January of this year. stuck even though his car showed 30 miles left on the battery.

But smarter AI models can only advance cars, Gasper says. Taking electric vehicles to new levels of extreme temperature resistance will also require advances in battery technology itself..

Best batteries

Scientists are trying several strategies to make batteries more weather-resistant. One promising method is to improve the electrolyte. Zheng Chen, a materials scientist and engineer at the University of California, San Diego, and his colleagues created a new electrolyte that performed well in laboratory tests at temperatures ranging from -40 degrees F (-40 degrees C) to as high as 122 degrees F (50 degrees C), according to study researchers published in 2022.

The team achieved this by mixing a lithium salt with a solvent called dibutyl ether, which easily bypasses lithium ions and remains liquid even at sub-zero and ultra-high temperatures. While the recipe is promising, it is difficult to say whether it will work on a large scale with commercially available battery parts. And this formula is probably not the only solution: automakers use different materials in lithium-ion batteries, which they are constantly improving to keep up with technological advances and provide, for example, more affordable components or greater range. According to Chen, no single solvent or metal salt will interact with all battery materials on the market.

While it's difficult to find electrolytes and other materials that will perform excellently under a variety of real-world conditions, Gasper says artificial intelligence can help speed up the discovery process. Researchers have programmed robots inspired by pharmaceutical industry technology alreadyuses for drug discovery to test candidate substances.

Some experts believe self-heating batteries could be another way to help electric vehicles cope with the cold. In 2018, scientists at Pennsylvania State University announced they created such a battery by incorporating nickel foil into it, which intercepts electrons when the battery temperature drops below room temperature. The captured electrons heat the foil, in turn heating the entire battery. Scientists say this will allow batteries to charge quickly even in temperatures as low as -58 degrees F (-50 degrees C). Other approaches such as using electric current pulses from a car engine, can also warm up batteries for faster charging in the cold.

But electric vehicle engineers face dilemma they call the “I Problem”: It’s difficult to design a battery that will perform effectively under a wide range of conditions. And remains affordable and durable. “We're kind of trying to balance cost, performance and safety,” Chen says. Automotive companies may approach these factors differently depending on their priorities. Some, for example, value higher performance over affordability and may use more expensive battery materials. This is why more expensive electric cars tend to have longer range.

Ultimately, it may be best to tailor battery designs to specific national and global climate conditions, Gasper suggests. Drivers in countries closer to the poles will use batteries adapted to the cold. Meanwhile, heat-resistant batteries will be especially important for people living in equatorial regions. There, faster chemical reactions caused by heat can degrade batteries, potentially leading to higher long-term costs for electric vehicles in regions where incomes are lower than the global average. “This is an economic justice issue,” Gasper says. The industry isn't there yet, but electric vehicle experts know it's a problem that needs to be addressed.