Super-light materials that help suppress EV battery fires just got a big boost

A company making fire-suppressing battery materials just got a $670.6 million loan commitment from the US Department of Energy.

Aspen Aerogels makes insulating materials that can be layered inside an EV's battery to prevent or slow heat and fires from spreading within the pack. The company is building a new factory in Georgia to produce its materials, and the DOE's Loan Programs Office will provide the massive loan to help it finish building the plant.

As more EVs hit the roads, concern is growing about the relatively rare but dangerous problem of battery fires. While gas-powered cars catch fire at higher rates, battery fires can be harder to put out and are at greater risk of reigniting, creating dangerous situations for drivers and first responders. Materials like Aspen Aerogels' thermal barriers can help improve battery safety.

I think the goal is to really make sure that they're helping to achieve critical battery safety goals that we all share," says Jigar Shah, director of the Loan Programs Office.

Automakers including General Motors, Toyota, and Audi already buy Aspen Aerogels materials to use in their vehicles. If the new factory starts as planned and ramps to full capacity, it could supply material for over two million EVs annually.

When a lithium-ion battery is damaged or short-circuits, it can go into a process called thermal runaway, a feedback loop of heat and chemical reactions that can lead to a fire or explosion. Electric vehicles' battery packs are made up of many small battery cells wired together-so there's a risk that a problem in one cell can spread to the rest of the pack.

The thermal barriers the company makes can be tucked between cells, creating an obstacle that can suppress that spread. Depending on how an automaker uses the materials, aerogel insulation can at a minimum slow down the propagation of thermal runaway, giving a driver enough time to get out of the car. Or automakers can use the materials to design batteries that can confine a bad cell or a group of cells, so instead of having a car-melting fire, you have a more isolated event," Young says.

Aerogels are very good at insulating to maintain hot or cold temperatures, since they're mostly made of microscopic pockets of air. Aspen won research grants from NASA to explore the use of its materials for spacesuits and other applications in the early 2000s, and it has sold materials for equipment in facilities including oil refineries and liquefied-natural-gas terminals in the decades since, says Don Young, the company's CEO.

The company began using its aerogels in battery materials in 2021. The start was a partnership with General Motors, Young says-the automaker was having issues with Chevy Bolt batteries catching fire at the time.

While aerogels can help with the severity of battery fires, they can't entirely prevent thermal runaway events. Currently, we are not aware of any commercial technology that reliably prevents thermal runaway," says In Taek Song, a researcher at LG Chem and part of a team that recently published research on safety devices for lithium-ion batteries, via email. Lithium-ion batteries contain flammable materials and can store a lot of energy.

Automakers and battery manufacturers already put some measures in place to lower the risk of thermal runaway, including battery management systems that can detect and control battery conditions to prevent fires before they occur. Thermal insulation materials-including those made with aerogels-are part of the growing arsenal that can limit the damage if thermal runaway does occur.

One potential drawback to those materials is that they add bulk to a battery, which reduces energy density-the amount of energy that a battery can store in a certain volume or weight. Higher energy density translates to longer range for an EV, a crucial selling point for many drivers. The benefit of aerogels is that they're super-light, since they're mostly air-so they don't limit energy density as much as other materials might.

Aspen's thermal barriers are typically between one and four millimeters thick and can be stacked between cells. Depending on the automaker and vehicle in question, the cost to incorporate it in an EV runs between $300 and $1,000, Young says.

A pencil resting on a PyroThin thermal barrier to show its comparative thickness. COURTESY OF ASPEN AEROGEL

The market is ramping up quickly. When the company began selling its battery materials in 2021, it did roughly $7 million in sales. In 2023 it had reached $110 million, and that's on track to more than double again in 2024, Young says.

Aspen Aerogels currently makes materials for EV batteries at its factory in Rhode Island, which also makes materials for other businesses, including the oil and gas industry. We're just busting at the seams of that plant," Young says. The DOE loan will support construction of a new facility in Georgia, which will be entirely dedicated to making material for EV batteries. The plan is to have that facility running by early 2027, Young says.

This loan is to really get them at scale for their first commercial facility in Georgia," Shah says. The company will need to meet certain financial and technical requirements to finalize the funding.

This loan is critically important to us, to help us with the completion of that project," Young says.

Correction: A caption has been updated to correctly identify the material pictured as a thermal barrier.