Battery Breakthroughs

Jim Motavalli

Jim Motavalli | Apr 24, 2012

DENVER, COLORADO—Amy Prieto is intense. The Colorado State University assistant professor has a lithium-ion battery company that bears her name, and it just might be prepared for a breakthrough in a space that badly needs one. Li-ion batteries cost too much, take too long to charge, present some safety challenges and are range-challenged.

Could Prieto Battery, a spinoff company with technology developed at the university, address all these things at once? Prieto says it can, but her company is still in the developmental stage and in need of investment capital to build prototype batteries and test them. In theory, she says, it can deliver a li-ion battery that charges 1,000 times faster than a conventional one, reviving a smartphone in five minutes, and last through as many as 5,000 cycles.

Amy Prieto and her battery team at Colorado State. (Jim Motavalli photo)
Amy Prieto and her battery team at Colorado State. (Jim Motavalli photo)

The Prieto battery promises energy density that is orders of magnitude greater than anything seen before. In a car, 400-mile range is reportedly possible, with quick 10- to 20-minute charge times at 240 volts. It’s a solid-state battery with no liquid electrolyte (an electroplated coating is used instead), and tiny copper nanowires (1,000 make up the diameter of a human hair) to increase surface area at the anode. Says Prieto, “Nanoparticles are so small, therefore most of the surface reactions that you would never notice in bulk materials are pretty dramatic in a nanoparticle.”  There’s more: Toxic materials are replaced with benign and commonly used substances like citric acid. Here's how the company's tech works:

Prieto’s lab looked just the way I want battery labs to look—there were beakers of bubbling blue liquids, energized graduate students running around and high-tech battery analyzers with blinking red test lights. In a perhaps unique twist, her husband’s lab is right next door—the two were a package deal at Colorado State. 

Seen in person, the shiny copper foam anode looks something like a miniature Brillo pad, but it turns black when coated by the polymer electrolyte. It’s unconventional, definitely, but it’s also, she says, “scalable and cheap, and able to store more lithium for less weight. We’ve demonstrated very long cycle life.” The solid electrolyte ensures against shorts and fires, and 3D architecture means the lithium ions don’t have far to travel, resulting in 10X jumps in ionic conductivity and quicker charge times.

Prieto Battery’s copper foam. (Prieto Battery)
Prieto Battery’s copper foam. (Prieto Battery)

The technology invites comparison to another university-based solid-state battery spinoff, Sakti3, coincidentally headed by another woman, University of Michigan engineering professor Ann Marie Sastry. That company drew investments from GM Ventures ($3.2 million), the state of Michigan and Khosla Ventures. According to Stephen Cass of Technology Review, which says the company has one of the Top 10 emerging technologies, “Sakti3 could deliver the needed breakthrough by focusing on ways to economically mass-produce a new type of battery—a so-called solid-state battery—that can safely store more energy than a traditional lithium-ion battery, which would reduce the cost of electric and hybrid vehicles and extend their range.”

Ann Marie Sastry of Sakti3: Another solid-state battery pioneer. (University of Michigan photo)
Ann Marie Sastry of Sakti3: Another solid-state battery pioneer. (University of Michigan photo)

Sakti3’s battery tech is also still in the lab stage. Neither it nor Prieto Battery is going to dazzle the world with a high-performance car this year. Ahead of them, perhaps, is Envia Systems, whose chairman and CEO, Atul Kapadia, told me in February that automakers are already testing his batteries, which could be in production cars within a year and a half. He promised to cut the cost of cells in half, and triple energy density.

The company also said it could deliver cell energy of 400 watt-hours per kilogram at a cost of $150 per kilowatt-hour. These are huge claims, though also unverifiable except through a Naval Service Warfare Center test that verified the energy density. GM Ventures is a believer, though, and put $7 million into Envia.

IBM also says it is adding two new partners and getting closer to a 500-mile lithium-air battery. The Battery 500 Project is working toward developing a working prototype by the end of 2013 that can “power a family-sized electric car for 500 miles on a single charge.” According to IBM, “Lithium-air batteries borrow oxygen from the air as the vehicle is being driven, creating an air-breathing battery.  This results in lighter batteries with high energy density that extend the car’s range from a single charge.” Here’s an explanatory video:

The big challenge for all these companies is proving that their batteries work in the real world, not just in the lab. Shiram Santhanagopian, a battery engineer at the National Renewable Energy Lab in Golden, Colorado said that Prieto’s technology could be “great news at the materials level, and the 3D architecture is interesting.” But he added that the company has a long road ahead in proving that its chemistry is viable in actual batteries, and reliable in series production. “We are more cautious these days,” adds his colleague Ahmad Pesaran. “These batteries will have to reach the manufacturing stage, and that is a long-term effort.”

A simple test drive would unlock the investment that Prieto needs to get to commercialization, but that’s not possible at this stage. Prieto says her methodology is to proceed slowly, verifying the technology at every step. So far, she says, everything is working perfectly, but crossed fingers, rabbit’s feet and four-leaf clovers might help—along with the very solid science.

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