The active material in these batteries would be tritium, and it is claimed that radiation caused by the decay of tritium is deemed safe, and unable to penetrate even the outermost layer of skin. For those wearing watches that glow in the dark, it is radioactive tritium in action there, so fret not with this City Labs-designed battery. City Labs claim that this battery can withstand a temperature range of -50℃ to 150℃, in addition to shrugging off extreme vibrations and altitude changes. Needless to say, not having to charge your phone ever is great, but what happens in a few years’ time when the smartphone landscape changes, and this battery is no longer compatible with the newer generation of devices?