It also has a lower expansion coefficient that potentially reduces the susceptibility of the battery to overheating and triggering the battery fires that prompted a global recall by Sony in 2007.
The company also plans to use a different alloy for the positive electrode, made of cobalt, magnesium and nickel, that would also improve capacity by an unspecified amount. It would also reduce the dependence on potentially costly cobalt, which makes up the bulk of the electrode in today's batteries, Hitachi says.
Silicon alloy should be implemented in Hitachi's batteries by the end of 2009, while the cobalt mix should be ready elsewhere in the year. No mention is made of the company's exact plans for the invention, though lithium-ion packs are most often used for cellphones as well as notebooks and are likely to replace older nickel-metal hydride (NiMH) batteries in electric and hybrid cars.