A novel lithium-air battery could pave the way for electric passenger planes

With a record-breaking energy density.
Derya Ozdemir
Electric car battery pack.kool99/iStock

A team of researchers from Japan's National Institute for Materials Science (NIMS), backed by Japanese conglomerate SoftBank, has developed a lithium-air battery with a record-breaking energy density of more than 500 watt-hours per kilogram (Wh/kg).

To put that into perspective, the novel battery has nearly double the energy density of the battery used in a Tesla Model 3. In addition to achieving the highest energy densities and longest cycle life yet accomplished, the battery can be charged and discharged at room temperature, according to a study published in the journal Materials Horizons.

That's huge, as it might pave the way for the practical usage of lithium-air batteries. Once the technology reaches the commercial stage, these batteries could find their place in mobile phones, electric cars, and perhaps even electric passenger planes.

Lithium-air batteries take the center stage

A lithium-air battery is a kind of metal–air electrochemical cell or battery chemistry that generates electricity by oxidizing lithium at the anode and reducing oxygen at the cathode. It may one day be the ultimate rechargeable battery: It is lightweight and high capacity, with potential energy densities that are many times greater than those of conventional lithium-ion batteries. Because of these potential benefits, it may only be time before they find their rightful place in technologies such as drones, electric vehicles, and household electricity storage systems.

However, there are only a few lithium-air batteries that have been successfully manufactured. That's partly because a considerable fraction of lithium-air batteries by weight comprise heavy inactive components that do not directly participate in battery processes.

The team behind the novel battery had previously worked on the issue by developing unique battery materials that considerably improve the performance of lithium-air batteries. Now, by integrating these novel materials and fabrication techniques, they have created a brand-new lithium-air battery.

The new battery has an energy density of more than 500 Wh/kg, which is roughly double that of Tesla Model 3's 260 Wh/kg lithium-ion Panasonic battery.

The researchers also stated that the repeated discharge and charge response occurs at room temperature and that the battery's energy density and cycle life statistics are among the highest ever achieved.

The 500 Wh/kg threshold: Electric passenger aircraft? 

The 500 Wh/kg figure is significant as engineers regard it as the point at which regional electric passenger aircraft —which are sustainable, efficient, and close-to-silent— become feasible, according to an initial Forbes report.

"The figures they're talking about are interesting because they're at that pinch point where it will become feasible to have a medium distance electric flight—that's a bit of a holy grail," Patrick Wheeler, Global Director of the Institute of Aerospace Technology and a professor in the Department of Electrical and Electronic Engineering at the University of Nottingham, said to Forbes. "If you want all-electric flight over a large distance, the current lithium-ion batteries aren't going to do it, because they become too big and too heavy."

And it doesn't end there as the novel lithium-air battery could offer many other advantages. 

"What this does is give us a battery that is significantly better in energy storage than we have today," Wheeler said. "Range anxiety is still an issue for electric vehicles, so if you can replace the battery pack an electric car today with something that takes you twice, three times as far, that's going to be a good place to be."

The next step for the researchers is to develop higher-performance battery materials that they can integrate into the novel lithium-air battery to increase its cycle life. They can then accelerate attempts to put the battery to use.

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