Industry insiders say it has been developing, in a joint venture with Matsushita Electric, a lithium-ion battery that uses nickel, cobalt and aluminum dioxide.

FORBES: Magazine Article

Select S Series models sport a premium and elegant design in Black or White with magnesium and aluminum materials, and all of them incorporate a built-in lithium polymer battery that when coupled with the all new and advanced large-capacity optional sheet battery, you can stay mobile and unplugged for up to 15 hours.

ENGADGET: Sony VAIO S arrives stateside, brings along an advanced extended battery