A new kind of lithium-ion battery holds much more energy than previous versions, while still working well at high temperatures. It could prove useful for hybrid and electric cars, where high-density batteries usually come with safety risks.

Leyden Energy uses a graphite current collector and imide salt in the battery's electrolyte. These materials enable the battery to last longer and withstand higher temperatures; Leyden has declined to discuss how it achieved higher energy densities.

The company says the battery has an energy density of 225 watt-hours per kilogram. This falls at the high-end range of laptop batteries, and roughly 50 percent higher than lithium-ion batteries used in electric vehicles. The four-year-old startup expects to see its cells used by a tablet PC maker later this year, says Leyden CEO Aakar Patel.