It’s light. It packs a lot of energy. And it could make electric planes a reality. So when Amprius first announced its revolutionary lithium-ion battery pack, there were reasons to be enthusiastic. And cautious. The sector of battery developers is famous for making promises that it finds difficult to keep afterward.

But in the case of Amprius, a watershed moment might have occurred. Mobile Power Solutions (MPS), an independent verification lab testing the compliance, safety, and performance of batteries, has confirmed the disruptive properties of the Amprius cells.

Doubling the numbers

The report from MPS reads that the performance was at 500 Wh/kg and 1 300 Wh/liter, translating into an unprecedented ratio between power and weight, or power and size. To put it into perspective, one of the world’s most advanced batteries, the Qilin from CATL, reaches 255 Wh/kg. Tesla’s newest generation of 4860 cells equals 244 Wh/kg and 650 Wh/liter. So, the Amprius can do twice as well as the currently best performers in the lithium-ion family.

This means that twice the energy can be stored at the same size as those batteries. As a result, cars running on Amprius cells could double their range or cut the weight in half for the same autonomy. This would tackle some of the biggest hurdles in EV development and adoption.

Amprius remains more low-key in its findings, stating its batteries have a 20-30% higher energy density than conventional lithium-ion batteries. And compared to gasoline, it’s still miles under the 9 600 Wh/l from that good old gasoline derivative.

Silicon nanowires

The trick of Amprius is that it uses silicon nanowires for the batteries to store that extra energy. As their name suggests, these structures of silicon atoms are tiny and, therefore, benefit from a high volume-to-area ratio. As a result, they are used as anode material in lithium-ion batteries.

The challenges lie in scaling up their production. And because there are so many of them on a small surface, they are structurally less stable. Nevertheless, Amprius has received government funding of $1 million to start an assembly line. Moreover, the verification of the characteristics of the technology means it’s one step closer to bringing the cell to market. Also, Google and Samsung are investors.

Eyes on the skies

However, while Amprius doesn’t rule out automotive applications, it seems to be eyeing the skies first. The company has a deal with European aircraft manufacturer Airbus and announced in 2018 that it would supply the International Space Station with batteries for several experiments.

As for aircraft, an energy density of 400 Wh/kg is considered a turning point for turning battery-powered planes into reality. The test from MPS confirms Amprius doesn’t fail to set that bar.

Amprius is based in Fremont, California. The company was founded in 2008 by Dr. Yi Cui, a Stanford University professor who started commercializing a lab-developed battery project.