A startup backed by iPod designer Tony Fadell just emerged from stealth with $18.5 million to bring breakthrough batteries to market in massive quantities

• The battery startup Advano recently raised $18.5 million from investors including Tony Fadell, who's credited with designing the iPod and later cofounded the company Nest.
• Advano is among a handful of startups trying to develop lithium-ion batteries using the element silicon in part of the battery that stores charge.
• These batteries could store 20% to 40% more energy than traditional cells.
• Silicon is notoriously difficult to work with, but it's only one of the problems that battery startups face on the road to commercialization.
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In the booming business of batteries, energy density is everything.

The idea is simple: If companies can pack more power into a smaller space, they can make devices that are longer-lasting, lighter, or have more room for other features.

In the last three decades, the energy density of lithium-ion cells - by far the most widely used batteries on the market, found in everything from iPhones to electric cars - has grown only incrementally, according to Yury Gogotsi, a battery researcher at Drexel University.

A handful of startups say they're nearing commercialization of a breakthrough technology: a material, made with silicon, that could squeeze 20% to 40% more energy into lithium-ion batteries.

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Now, there's a new competitor - and it's bringing big backers to the fight.

Advano, a New Orleans-based battery startup, has just emerged from stealth mode, announcing that it raised $18.5 million from investors including Tony Fadell, who's credited with designing the iPod and founded the smart thermostat company Nest, in addition to Peter Thiel's Thiel Capital and Y Combinator.

Advano says its silicon-based material can improve the energy density of batteries by up to 40% and overcome some of the obstacles others have run into.

Experts say that might be possible, assuming the company is really able to overcome silicon's notorious challenges. If it does, the next step will be bringing the material to market.

"No one has ever been able to make it work before," Gene Berdichekvsy, the founder of Sila Nanotechnologies, a rival company, told Business Insider last year. "The problem in batteries isn't coming up with a cool new piece of science."

The promise and perils of silicon batteries

In a typical lithium-ion battery, ions of the element lithium - which generate charge - are stored in a carbon-based material called graphite, the same material found inside pencils.

The amount of energy inside a cell is limited, in part, by the number of ions that graphite can store. So one way to increase a battery's energy density is to simply use another material, in place of graphite, that can store more ions - like silicon.

Silicon is a storage superstar. One gram can store about 1,000 milliamp hours, a measure of electric charge over time, according to Matthew Keyser, a battery expert at the National Renewable Energy Laboratory (NREL). In comparison, graphite can store only about 350 milliamp hours per gram, he says.

That's why so many battery companies are chasing after silicon.

"If you're not working in silicon, you're behind," Alexander Girau, the founder and CEO of Advano, told Business Insider.

But as useful as it is, silicon has a few major drawbacks.

For one, it expands in size by a factor of three as it absorbs ions of lithium, Keyser says. That can cause cracking, which can, in turn, disrupt the flow of ions.

Silicon-based materials are also prone to rapid degradation. After a discharge cycle, the amount of energy they can store might drop from 1,000 to 500 milliamp hours, Keyser says.

Why? It's pretty complicated, but basically a reaction occurs between silicon and another part of the battery known as the electrolyte. The reaction eats up electrolyte and lithium to form a thick crust on the surface of the silicon that impedes the flow of ions.

Advano's solution: A sponge-like structure made of carbon

Advano has a clever way of getting around the pitfalls of silicon.

"We don't fight physics, we accommodate physics," Girau said.

To accommodate the expansion of silicon, Advano puts tiny specks of the element inside a sponge-like porous structure made of carbon. As silicon absorbs the ions, it expands inside the holes of the sponge, yet the volume of the sponge stays roughly the same, so it doesn't crack.

The advantage of this approach, Keyser says, is that the resulting product - a powder made of these sponge-like particles - can be dropped into existing cell manufacturing pipelines because it's similar in size to graphite. That makes it much easier to market and mass-produce.

"The Holy Grail is a drop-in replacement," Girau said.

To get around the issue of degradation, Girau says Advano has developed a technique to protect the surface of the silicon from the electrolyte.

The biggest challenge battery companies face is scaling up production

Most long-gone batteries companies don't fold due to poor science but their inability to scale - to move their tech from an academic lab to mass-scale production, Girau said.

He said this is where Advano plans to stand out, partly because it's not based in Silicon Valley, but New Orleans.

"If there's one thing we know how to do very well here, it's manufacturing lots of chemicals," Girau said. "We routinely hire from Dow, Exxon, Albemarle - places where people know scale. That's the real battery problem."

Advano has another advantage, he says: sourcing recycled silicon.

Silicon isn't rare or expensive. But Girau says there's a lot of processing involved in converting silicon, as it's found in nature, to a usable form. That process costs money and pollutes, he says.

"We bypass all of that and focus on using an abundant, affordable, raw material," Girau says, which "a lot of people consider waste."

Keyser of NREL doesn't see a huge advantage to this approach. He simply doesn't think there's enough recycled silicon in the market for mass-scale production, though he says it could end up saving costs.

iFixitNew silicon-based lithium-ion batteries could make phones and other consumer electronics last longer.

Advano is targeting consumer electronics

Advano is now finishing construction of a facility that's capable of producing 10 tons of its material a year, Girau says, which is enough to supply batteries for 10 million iPhones.

Like the startup Sila Nanotechnologies, Advano will initially sell its material to battery cell manufacturers who create products for the consumer electronics industry. Girau says the industry is looking for a 10-20% improvement in energy density.

Eventually, he said, he hopes to sell Advano's product to companies who manufacture batteries for electric vehicles.

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