New Lithium-Air Battery Makes Larger Electric Aircraft Possible

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The aviation industry has been achingly slow to loosen its grip on kerosene jet fuel. Signs of change have been brewing in the field of battery-powered electric aircraft, but so far the focus has been on flying machines at the smaller end of the scale. Full sized cargo and passenger planes represent a next-level challenge, requiring a new generation of lighter, higher-performing batteries. As if on cue, the US startup Air Energy has come up with a solution…

The Long Road To A High-Density Battery For Electric Aircraft…

If you’re thinking solid state lithium-air batteries are in play, run right out and buy yourself a cigar. Lithium-air is one of those futuristic energy storage technologies that seemed to be going nowhere not too long ago. The idea was to use oxygen as a key ingredient in a rechargeable lithium-based battery, thereby saving considerable weight while potentially boosting energy density far beyond the capacity of ordinary lithium-ion technology.

The vision of a lithium-air battery refused to die, though. Support from the US Department of Energy kept research programs in the US afloat during the early 2000’s, complementing other Obama-era R&D activity in support of electric aircraft.

There being no such thing as a free lunch, the pursuit of lithium-air technology was a minefield of engineering challenges. Persistence began to pay off in 2013 when the Energy Department’s Argonne National Laboratory spotted a yawning gap in the field. “Nearly all the literature on Li-air batteries so far focused on the chemical processes at cathode while assuming the anode is completely reversible,” Argonne electrochemist Di-Jia (D.J.) Liu explained, with the cathode being the point where oxygen interacts with the battery.

The cathode-centered assumption was mistaken, as the Argonne team discovered. Deploying the lab’s Advanced Photon Source equipment to view a lithium-air battery in real time, they observed lithium hydroxide forming on the anode during operation, causing the battery to degrade.

That solved one mystery only to uncover others. “I think that we generated as many questions as answers through this study,” Liu concluded. On the up side, Liu also noted that the act of generating questions is the “exciting part of science.”

…Finally Got A Bit Shorter…

Ten years later, in 2023 the lab was back with a more optimistic perspective under a research partnership with the Illinois Institute of Technology. The joint effort yielded a lithium-air battery intended for electric passenger car market as well as electric aircraft and long-haul trucks.

The new battery replaced the liquid electrolyte used in conventional lithium-ion batteries with a solid electrolyte. Overall, the lab anticipated that their new battery would outperform a typical Li-ion battery on energy density by up to four times.

“The team’s new solid electrolyte is composed of  a ceramic polymer material made from relatively inexpensive elements in nanoparticle form,” the lab explained.

“The team’s lithium-air design is the first lithium-air battery that has achieved a four-electron reaction at room temperature. It also operates with oxygen supplied by air from the surrounding environment,” the lab added, noting that the use of ambient oxygen eliminates the need for storage tanks.

…And Shorter.

As of 2024 the Energy Department was still funding lithium-air projects focusing on the EV market. In the meantime, research at Argonne also spun off into the Chicago-based venture Air Energy, which has focused its initial efforts on electric aircraft.

The Energy Department provided the new startup with a leg up by including it, in partnership with the Illinois Institute of Technology, in the JOULES 1K funding program. Short for “Jumpstart Opportunities to Unleash Leadership in Energy Storage,” JOULES 1K sets a high bar, requiring funded projects to achieve an energy density of at least 1,000 watt-hours per kilogram and 1,000 watt-hours per liter, both at end-of-life and at system level.

“Technologies developed in the JOULES-1K program must be distinct from traditional energy storage and battery solutions to achieve these ambitious targets,” the Energy Department emphasizes.

In addition to pushing the envelope on battery technology, the program also focuses on electric mobility applications beyond the capability of traditional fossil fuels. “The JOULES-1K program aims to propel U.S. energy leadership across applications of economic and national security interest including Electric Vertical Take-Off and Landing (eVTOL) aircraft, drones, Unmanned Underwater Vehicles (UUVs), Unmanned Surface Vessels (USVs), robots, portable electronics, and others that require ultra-high density energy storage systems,” the Energy Department elaborates.

Follow The Money

With the Energy Department’s seal of approval in its pocket, last month Air Energy announced an oversubscribed round of seed funding to help prep its forthcoming solid state lithium-air battery for full scale manufacturing.

“Air Energy is developing rechargeable solid-state lithium-air batteries designed to enable larger electric aircraft, dramatically extend drone endurance, and unlock new mission capabilities for autonomous systems,” the company emphasized in a press statement celebrating the undisclosed sum.

“Larger” is somewhat relative. Electric aircraft are becoming fairly commonplace in the form of unmanned drones. Limited-seating aircraft are also beginning to emerge for regional travel, along with small cargo planes and helicopter-adjacent eVOTL flying machines.

Full scale cargo and passenger planes represent a next-level challenge that is not on Air Energy’s horizon as of this writing. Nevertheless, the investors behind the haul claim substantial footprints in defense and advanced manufacturing as well as financial firepower. “The oversubscribed seed round includes participation from strategic and institutional investors, led by Resolute Venture Partners—early investors in Tesla and SpaceX—along with Illinois INVENT, Illinois Tech, Evergreen Climate Innovations, Leslie Ventures, LLC, and strategic angel investors,” Air Energy noted.

“The round was initiated by Leslie Ventures, led by Mark Leslie, Founder and former CEO of Veritas Technologies, which reached $64 billion in value during his tenure as Chairman,” the company added.

A New Battery For The Electric Aircraft Of The Future

The seed funding will enable Air Energy to hire more engineers and fine tune its manufacturing process, aiming at pilot scale production. The company also hints, without further elaboration, at collaboration with “key” partners in government and the private sector.

The plan appears to be on track. On June 22, the news organization Aviation Week reported that the Air Energy/Illinois Tech team won a contract from the Trump administration earlier this year to continue their work on Phase II of JOULES 1K, leading to the launch of a pilot-scale fabrication line next year.

The two-year phase will include drone flight tests with the new battery in the form of pouch-type cells. The company is also targeting 2,000 watt-hours per kilogram, so keep an eye out for a broad range of applications.

Photo: A new lithium-air battery is heading towards pilot-scale production, offering less weight and higher energy density for electric aircraft (electric passenger plane in flight courtesy of Beta Technologies).