Such is the case with Nopopo battery.
Nopopo (NoPolutionPower) batteries are whiz-activated! The batteries use a combination of magnesium and carbon that, when mixed with certain fluids (including urine, y'all), produce a charge. Sha-zam!The Nopopo doesn't produce a lot of juice out of your pee - less than a normal AA alkaline battery. The upside is in the recycling, I guess.