There’s been a bit of a buzz in battery research lately as chemists have made great strides in truly powering life by the “air you breathe“. What on earth does that mean aside from being a pointless reference to infomercials I’m obsessed with? (Aside: This is actually a problem, I once watched the full half-hour Magic Bullet infomercial because I was bored). While my previous post talked about researchers redoing a battery idea of Edison’s, this team at the University of Southern California was tinkering with a more recent design: “breathing batteries”. Breathing batteries are basically powered by the rusting of iron by oxygen, though it seems the “breathing” is a bit of a misnomer since the journal article mentions the chemical reactions occurring in liquid (although a lot of literature still uses the term “air”).
Iron rusting actually produces a lot of energy. If you’ve ever had one of those disposable hand warmers, odds are it was mostly filled with just iron filings and a few other chemicals to speed up the reaction. But all the heat is coming from the iron corroding REALLY fast. Iron-air batteries have been around for decades and became very popular during the 1970s energy crisis. But like the Edison batteries, they fell out of favor when other battery chemistries proved to be more efficient. Aside from oxygen rusting the iron, there’s a second reaction in the battery that takes charging current and produces hydrogen, and this could take up to half of the energy. They’ve come back into vogue for similar reasons to the iron-nickel batteries: the materials are abundant (and cheaper) and safe for both people and the environment. The Department of Energy hopes improving their efficiency could make for reasonable energy storage in a shift to a renewable energy power grid.
So what made the USC batteries so much better than before? Pepto-Bismol. Seriously. The active ingredient of Pepto-Bismol, bismuth sulfide, was added to the iron electrode. The bismuth prevented hydrogen formation, and reduced the energy loss to only 4%. It also helped improve how much energy the battery could hold and how quickly the energy could be released, both of which are important factors for storing energy meant for the power grid.