How To Build A Quick-Charging Electric Battery

How To Build A Quick-Charging Electric Battery 

No one promised that going green would be easy. Just look at the up and down story of technology innovator Altair Nanotechnologies.

Altair makes a nano-particle compound used by Boeing to coat the wings of its stealth fighters and by paint maker Sherwin-Williams to make pigments with fewer toxic residues. But Altair has grander plans: It aims to make batteries that can power an electric car for 150 miles and recharge in the same amount of time it takes to fill up a gas tank and grab a Big Gulp.

The technology seems to be getting close to practical application. Phoenix Motorcars, a Rancho Cucamonga, Calif.-based electric vehicle start-up, plans this year to start selling a small electric pickup truck with drive batteries based in part on the Altair technology. That said, precisely how many Phoenix will buy isn't clear. (Phoenix reported in November that it was scaling back its plans to purchase at least $16 million of batteries from Altair.)

Altair's designers say that the key advantage of their battery is that it can in principle be recharged in an unprecedented 10 minutes. Making this a reality, however, depends on building out a network of high-voltage charging stations. That may be easy for one of Phoenix Motor's first customers, namely Pacific, Gas & Electric. PG&E owns its grid. Others, however, may find setting up the logistics for recharging stations more daunting.

Still, enthusiasm is high within Altair, which raised $40 million from Dubai investment company Al Yousuf in November, even as Altair reported operating losses of $17 million for the first nine months of 2007.

Altair has staked its future on 40-nanometer-size particles of lithium and titanium. It uses the particles to make a coating that covers a battery's anode, an aluminum bar that carries electricity to and from the vehicle's motor. By contrast, most hybrid cars, including Toyota's Prius, use a graphite coating, in conjunction with nickel metal hydride or lithium ion batteries.

The difference is material: When a battery operates or recharges, ions pass through the coating of the anode. Graphite isn't very porous, so the ions literally deform the material as they force their way through.

"This builds up stress and over time the graphite cracks, leading to high resistance and short life," says Altair Chief Executive Alan Gotcher. Altair's nano-titanate coating, by contrast, has a large surface area. That means fewer ions try to force their way through at any given point, lowering resistance and minimizing damage.

By bypassing the graphite design, Altair also avoids dangerous overheating--or thermal runaway-–that can plague large lithium ion batteries. Thermal runaway became a buzzword in 2006 when a Dell laptop computer spontaneously caught fire in a Japan office, an event captured on videotape and instantly shared via YouTube.

Gotcher says his nano-titanate battery lasts for 20,000 full recharge cycles. That's about 20 years, four times the life span of a comparable NIMH or lithium ion battery.

Altair started out as a materials research lab of mining giant BHP Billiton. In 1998, during a downturn in the mining industry, BHP sold the lab to Altair, at the time a shell company.

Tim Spitler, a former DuPont chemical engineer in that lab, spent the next four years learning how to use lithium-titanate to improve batteries. He and his colleagues devised a method to heat treat, mill and spray the material, which looks like a fine white powder, onto the bare aluminum anodes. That gave Altair a way to use lithium-titanate on a commercial scale. But the work didn't dovetail with plans by bigger companies, and the project was shelved.

When Gotcher joined Altair in 2004 he figured the company had a shot at making batteries fully in house. He raised $3.5 million in a secondary stock offering and hired a team engineers to build a working product. Last year Altair made 130 tons of raw lithium-titanate powder at the old BHP lab in Reno. It assembles 35-kilowatt batteries for the likes of Phoenix Motorcars at its factory in Anderson, Ind.

Then there's the challenge of where to get the big dose of power to recharge the batteries.

Phoenix recharges its electric truck battery in 10 minutes with a 440-volt charger--four times the amount of energy in a home wall socket. Scaling that operation, however, would be a challenge: Existing electric grids couldn't easily handle the power drain of rapidly recharging millions of such electric batteries.

So in early January Altair also built its first pair of industrial 1-megawatt batteries--each about the size of a freight car--designed to store excess electricity produced at night. The Virginia power utility AES plans to use the mega-batteries to warehouse power for use during peak consumption times.

Such batteries could help Altair offer 10-minute recharges to the masses. Futuristic filling stations might feature massive batteries below ground, replacing the gasoline storage tanks of today.

Without such infrastructure, going green will certainly take more time. “Five-hour charges would be the fastest possible for residential drivers,” admits Bryon Bliss of Phoenix Motorcars.