As the name implies, Lilliputian Systems is developing tiny fuel cells that the company says will be usable in consumer electronics like cell phones and laptop computers.

Although secretive, the company has made claims that its butane-fueled cells will be far cheaper, and run for much longer, than current battery technology. It has not yet announced plans to manufacture or sell the cells.

Lilliputian is backed by Atlas Ventures, Kleiner Perkins Caufield & Byers, Rockport Capital Partners, and new investor DAG Capital. The $20 million round is an addition to a $30 million third round raised some two years ago.

Here’s a bit more on the technology from a Forbes article:

…Lilliputian Systems, a four-year-old Wilmington, Mass. firm, has produced a matchbox-size fuel cell that can put out enough electricity to run a laptop computer for days. Instead of alcohol, it runs on butane, a cheap and far more potent source of energy by volume.

While Lilliputian hasn’t announced an agreement with a big manufacturer, Chief Executive Kenneth Lazarus says he’s talking to most of them. He figures the company’s first product will be a portable battery recharger for laptops and smart phones. Current rechargers using flashlight batteries cost as much as $5 per charge, while a Lilliputian device could get 25 charges from a $2 cartridge of butane. Mass production should be easy because Lilliputian’s fuel-cell chip can be made using 20-year-old semiconductor manufacturing equipment prevalent throughout Asia….

One of the biggest challenges was figuring out how to integrate the ceramic electrolyte into the silicon. The ceramics they were using expanded four times as fast as silicon when heated. The solution Lilliputian came up with is a trade secret, but the company does admit it uses a network of fractures to absorb the stress, much like the expansion joints in a sidewalk.