Air-breathing “rust” battery may provide low-cost energy storage
By Anthony Capkun
August 1, 2012 – A team of researchers say they have developed a cheap, rechargeable and eco-friendly battery that could be used to store energy at solar power plants. Led by Sri Narayan, professor of chemistry at the University of Southern California (USC) Dornsife College of Letters, Arts and Sciences, the team developed an air-breathing battery that uses the chemical energy generated by the oxidation of iron plates that are exposed to the oxygen in the air—a process similar to rusting.
“Iron is cheap and air is free,” Narayan said. “It’s the future.” As currently developed, Narayan’s batteries have the capacity to store between 8- and 24 hours-worth of energy.
Iron-air batteries have been around for decades, says USC; they saw a surge in interest during the 1970’s energy crisis, but suffered because the hydrogen generation that takes place inside the battery (hydrolysis) sucked away about 50% of the battery’s energy, making it too inefficient to be useful.
Narayan and his team managed to reduce the energy loss down to 4%, making iron-air batteries that are about 10X more efficient than their predecessors. The team did it by adding very small amount of bismuth sulphide into the battery. Bismuth (which happens to be part of the active ingredient in Pepto-Bismol and helps give the pink remedy its name) shuts down the wasteful hydrogen generation.