A battery that runs on air? Why, thatâ€™s almost as good as a car that runs on water! Those cars are fantasy, but batteries that run on air are actually quite common, especially among older people. Tiny zinc-air batteries are widely used in hearing aids, where they have replaced toxic mercury-based batteries in providing a small but steady stream of power. They supply more energy for their size than any other battery, because they draw some of their power straight from the air.
“Batteries Out of Thin Air”