Thinking small yields big boost in power

FORT COLLINS – A movie called Revenge of the Electric Car premiered at this year’s Tribeca Film Festival in New York. It’s not a horror flick, but a followup to the 2005 documentary, Who Killed the Electric Car? Six years later, the same director is now suggesting that the demise of electric vehicles was greatly exaggerated.

From a small laboratory on the second floor of the Chemistry Building at Colorado State University, Amy Prieto and her team of scientists are trying to lead the electric-car revival. Using nanowire technology, Prieto has developed a lithium-ion battery that can run 1,000 times stronger and 10 times longer than conventional lithium-ion batteries and other alternatives, such as nickel-cadmium cells.

Her company, Prieto Battery, has recently added a chief financial officer and marketing vice president to enable CEO Prieto to concentrate on technical work. Early tests continue to meet and exceed expectations, and Prieto Battery could have products ready for commercial sale as long-lasting, rapid-recharge cell-phone batteries in the next few years.

“There’s such a high demand for better batteries in so many different markets,” Prieto said. “We thought one (battery application) would be obvious, but there are five or six.”

And while a high-performance battery for cell phones and laptops are among the opportunities Prieto has her eye on, she’s also focused on the grand prize of battery innovation: the electric car.

The so-called – and seemingly premature – death of electric vehicles has been partly attributed to Detroit and D.C.’s past resistance and indifference. The lack of interest slowed progress on building a better battery, one that allows drivers to open up on the open road and travel long distances without having to stop and recharge every hour.

“The performance is there,´ said Ahmad Pesaran, energy storage task leader at the National Renewable Energy Laboratory in Golden, of electric batteries. “It’s just the life cycle needs to come up and the cost needs to come down.”

The auto industry and the White House have both come around. Chevrolet and Nissan recently released electric plug-in cars, and Ford and other carmakers are slated to roll out their own electric vehicles this year. And then there was the suggestion by President Barack Obama, in his 2011 State of the Union address, that the nation should aim to have 1 million electric vehicles on the road by 2015.

To go along with the big words, Obama pledged $2.4 billion to support research and development in the electric-vehicle sector. Some of the money has gone to NREL to build up its battery-testing capabilities, while other funds have been made available as grants to researchers and startups, such as Prieto Battery.

A chef of chemistry

Amy Prieto began studying nanostructures in graduate school at University of California in Berkeley, and then continued her research during a postdoctoral appointment at Harvard. When she joined the chemistry faculty at CSU in 2005, she turned her attention to lithium-ion batteries and how to enhance their performance through nanotech.

Prieto launched Prieto Battery in 2009 with support from CSU’s Clean Energy Supercluster, known as Cenergy. The company received a total of $1.5 million through CSU and Bohemian Foundation to get off the ground and develop the technology.

“My real expertise is figuring out how to make things,” Prieto said. “In the chemistry world, I’m kind of what a cook would be.”

Conventional lithium-ion batteries are composed of a positive (graphite) and negative (lithium) electrode separated by an electrolyte. The electrodes are arranged in layers – in cylinder batteries, the layers are rolled – and the ions pass back and forth as a battery spends its energy and then gets recharged. In order to avoid overheating and shorting, the electrodes need to be sufficiently spaced from each other, which limits the cell’s lifespan and adds to recharge time.

Prieto cooked up a new recipe using copper nanowires – so small that 1,000 add up to the width of a human hair – in place of the graphite electrode. The arrangement creates a three-dimensional interior structure in a battery that can handle twice as many lithium ions as graphite, due to the surface area of the nanowires. The material’s stability and heat resistance diminish concerns about frying the battery, and the nano-enhanced cell has shown elevated power and energy levels beyond those of typical cells.

“I don’t know of any other company that’s trying the three-dimensional approach we’re trying,” Prieto said.

The performance boost also means less battery space is needed in the back of a cell phone – or under the hood of a car. The all-electric Tesla Motors Roadster, which became the first such vehicle available in the United States in 2008, can go from zero to 60 in under four seconds and run for 240 miles between charges. But to meet those benchmarks, the car has over 6,800 lithium-ion cells equal to the same number of laptop batteries. The technology of Prieto Battery could dramatically reduce the size of such configurations.

Building momentum

Pesaran of NREL, who oversees battery testing for products of small and very large companies, said the results that Prieto has announced so far are “significant,” without being incredible. But, he added, there are hundreds of companies trying to advance lithium-ion batteries and other electric alternatives. The electric car will likely be avenged through the technology of many businesses.

Prieto plans to continue to run prototypes in the tight quarters of the CSU lab and to enlist third-party testers, such as NREL, to produce their own results. The company’s latest tests have shown that its batteries could fully recharge a cell phone in minutes, instead of hours, another promising development.

“We’re so close on this next prototype. It’s really exciting,” Prieto said. “Some of the breakthroughs made recently were kind of the highest risk part of this project, so now that we have good evidence it’s going to work, we’re building momentum.”

Prieto Battery is pursuing its second round of investment, up to $6.25 million, through this fall, and the company should find out in July if it has won a $5 million federal grant. The company has also “generated a lot of interest” from venture capital groups, Prieto said.

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