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The secret sauce powering Amprius' push to make battery-powered flight a reality
New 500 Wh/kg battery announced this year
Last year, the all-electric Eviation Alice aircraft had its first test flight. Impressive as it was, there was one major problem. The parent company Eviation hasn’t yet found a battery that can power the Alice for its intended 250 nautical mile range.
Eviation CEO Greg Davis admitted to the Seattle Times that “Eviation needs still-to-be-developed advances in battery technology to make its planes commercially viable.” Davis surmises this could be five years away.
So why run demonstration flights when the technology isn’t there yet?
One reason is that aircraft testing isn’t limited to just the battery; thousands of other parameters need to be validated.
But there’s another, bigger reason: the importance of demonstrating progress to the outside world.
“They need to show a prototype that could conceptually work. So they shift resources from what they ought to be doing to what they need to be doing, which is - get the cheapest possible batteries. And let's throw them in there. And let's show that I can take off, but instead of flying for three, four hours, it's going to fly 20 minutes.”
The $100 billion industry
Battery companies are hot property at the moment. The market was valued at over $100 billion in 2022. In fact, this number will increase by 15% every year up to 2030.
That’s because batteries are crucial to helping a range of different sectors transition away from fossil fuels. As well as the aviation and automotive industries, battery development matters for various other sectors, from defence to medicine.
Transportation has an increasing number of electric advocates who say we need to prioritise batteries, as it is less resource intensive than other solutions.
Responding to it. Andrew Sissons from thinktank Nesta wrote:
“There is a very simple trick you can use to separate good ideas from bad ideas in the energy transition: ask “how much clean energy does it need?”
Sissons claims that e-fuels need 5x as much clean energy (used in e-fuel production) compared to having an electric battery move a vehicle the same distance.
“Because (we) need to replace the fossil fuels we use for all sorts of things — electricity, heat, transport, industry — we need lots more clean energy. So we need to use that clean energy as efficiently as we can (or avoid using it altogether).”
Batteries may present the best use for renewable energy. However, there’s a problem with how much energy a battery can hold, or how heavy it needs to become to power electric aircraft for any meaningful distance.
That’s why the Eviation Alice can currently take off, fly for a little bit and land again. It can’t do much else.
The benefits of silicon
California-based Amprius believes it can make the electric flight a reality thanks to the technology it uses — using silicon rather than graphite in its lithium-ion batteries.
Amprius says that silicon is the best material for energy density, with a 100% silicon anode having 10x the capacity of graphite.
“Traditional conventional cells use graphite as the anode material. Conventional batteries have literally met the theoretical maximum for how much energy density it can hold”, says Tao.
“So the only way you move up from graphite is advanced technology. Now there's a lot of talk. You'll hear lithium metal; you’ll hear lithium sulphur. None of that is commercial.”
When it comes to lithium metal, which has been touted as a particularly promising battery solution, Tao is especially sceptical, saying that there is a joke about Lithium metal batteries:
“Lithium metal is thought of as the battery of the future. And it will always be thought about as the battery of the future. That's the joke.”
“The only thing that you can actually get in the market is silico-based. Amprius is the only company in the world to commercialise a 100% silicone anode, meaning it consists of silicon, and nothing else.”
Earlier this year, Amprius was one of two companies to announce a 500-watt-hour per kilogramme (Wh/kg) battery, representing a big jump forward in battery energy density. For context, the batteries in today’s Teslas cars deliver around 265-280 Wh/kg.
The other company was the largest battery manufacturer in the world, China’s CATL.
At the Auto Shanghai trade fair, CATL said that its new battery would accelerate the “electrification of sea, land and air transportation, open up more possibilities of the development of the industry, and promote the achieving of the global carbon neutrality goals at an earlier date.”
Tao says that Amprius is further down the road than CATL, “We have a product, they don't.” Tao further points out that the energy density performance of the Amprius battery has been independently verified by Mobile Power Solutions, a testing house offering battery regulatory compliance, safety and performance testing.
The Amprius battery announcement also included an endorsement from AALTO HAPS, the Airbus subsidiary developing the 100% solar-electric High Altitude Platform Station for connectivity and earth observation applications.
Transatlantic battery-powered flight in the 2030s?
Tao believes that doubling the energy density further to 1000 Wh/Kg is achievable.
“It's possible because our core technology, our 100% silicon anode, is boundless in terms of how much you can do. So advances in the other areas of the battery is what's going to allow us to continue to pull up.”
Tao even speculates that the next decade could see the development of a battery good enough for a transatlantic flight, though he’s careful to qualify that by saying that this is more likely to be — at least initially — for a private jet type of plane. Moreover, he notes that there’s a difference between having the battery ready and having an aircraft certified to fly on it.
“I'll tell you why I am optimistic — necessity is the catalyst of invention. And everybody sees that energy density is absolutely necessary right now.”
Amprius makes a lot of bold claims. It’s worth noting that this isn’t a small start-up. Amprius has been around since 2008, has a credible management team and has 80 patents to its name.
It is also about to significantly scale up, having selected a site in Colorado for a 775,000-square-foot gigawatt-hour scale factory. It may be safe to conclude that battery technology has moved beyond small gains every year and is instead about to see some real leaps forward.
While that still may not be enough for transatlantic flight by the 2030s, Cosmic Aerospace, another company in the electric aircraft space is already planning an all-electric regional aircraft that can fly 1000 km (see our article on Cosmic).
As Tao says, “We've never seen this level of investment in innovation within the battery industry for over 30 years. This is the most exciting it has been in the industry.”
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