Amprius Raises $25M: Better Li-ion Batteries on the Way?

Amprius wants to take its lithium-ion battery technology from the labs to commercial-scale. On Thursday, the Menlo Park, Calif.-based startup got the ball rolling with a $25 million Series B investment to help it move toward its first commercial product, likely for the consumer electronics market.

The round was led by Silicon Valley VC powerhouse Kleiner Perkins, and Chinese firms IPV Capital and Qian Neng Fund, and included previous investors such as Google (s goog) CEO Eric Schmidt, VantagePoint Venture Partners, Trident Capital and Stanford University.

That’s a pretty hefty roster of backers, but Amprius’ technology, developed by company founder Yi Cui at Stanford, promises a pretty powerful boost to lithium-ion energy density. The secret sauce in this case is using nanostructured silicon material in the battery anode, or the material that absorbs lithium ions in the battery — a line of research Cui has been working on for years.

Amprius’ technology promises the ability to shrink the anode roughly fourfold from today’s carbon-based anode material technology, CEO Kang Sun told us last year. That could allow a fourfold increase in energy density if concurrent improvements in cathode technology can keep up, which is an uncertain prospect, to be sure.

Even so, Amprius’ technology could offer lithium-ion batteries an energy density boost far greater than the 5-percent-per-year improvements typical for the industry over the past decade or so, Ryan Kottenstette, director of business development, told me Thursday.

Amprius’ other challenge has been to engineer the silicon in a way that extends its stability over repeated charges and discharges, to make sure it can serve in batteries that demand long cycle lives such as automotive batteries. Amprius said last year it had demonstrated the ability to put its anode material through 250 cycles before seeing capacity drop below 80 percent — about halfway to the standard goal of 500 cycles for a consumer electronics battery, though still far from the thousand-plus cycles typically demanded of vehicle batteries.

Thursday’s announcement said Amprius had “recently achieved key validation milestones” for consumer electronics applications, though it didn’t give specifics on how many cycles those recent milestones added up to. The startup also said it would “advance toward requirements necessary for electric drive vehicle applications” using its new funding, though it didn’t give specifics on when that might come out.

As for what commercial products Amprius will be targeting, Kottenstette declined to go into specifics about whether or not the company was working with any specific battery manufacturer on any specific product. Still, he said consumer electronics are a natural target to test out new battery technologies, since the market cycles are faster and the cycle demands less stringent than in the automotive sector.

Amprius launched in 2008, raised about $5.8 million in a 2009 Series A round, and in 2010 secured a $3 million grant from the National Institute of Standards and Technology’s Technology Innovation Program.

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Image courtesy of Amprius.