Mercury-free silver oxide battery - those things had mercury in 'em?

We always knew that batteries have the honor of being the single most toxic element out of any electrical device we own - we're thinking that's why our battery-sucking kid brother developed that weird tick. But Sony announced that they've made the silver oxide battery disc battery a little greener. The silver oxide battery is the one used in wrist watches and handhelds games, and in the past the battery always needed mercury to stop corrosion. But now Sony says they've developed the technology to take out the mercury without the previous corrosive result. We really have no idea how they did it, but we applaud taking mercury out of the occasion. Now start working on those thermometers.