Hydronium, also known as H 3O+, is a positively charged ion produced when a proton is added to a water molecule. Researchers in the OSU College of Science have demonstrated that hydronium ions can be reversibly stored in an electrode built with perylenetetracarboxylic dianhydridem (PTCDA, above), an organic, crystalline, molecular solid. The battery, created in the Department of Chemistry at Oregon State, uses dilute sulfuric acid as the electrolyte and has an energy density of 85 mAh/g at 1 A/g current.
"This may provide a paradigm-shifting opportunity for more sustainable batteries," said Xiulei Ji, assistant professor of chemistry at OSU. "It doesn't use lithium or sodium or potassium to carry the charge, and just uses acid as the electrolyte. There's a huge natural abundance of acid so it's highly renewable and sustainable."
Ji points out that until now the cations - ions with a positive charge - used in batteries have been alkali metal, alkaline earth metals or aluminium.
"No non-metal cations were being considered seriously for batteries, and organic solids are not typically contemplated as crystalline electrode materials, but many are very crystalline, arranged in a very ordered structure," said Ji. "This PTCDA material has a lot of internal space between its molecule constituents so it provides an opportunity for storing big ions and good capacity."
"It's not going to power electric cars," Ji said. "But it does provide an opportunity for battery researchers to go in a new direction as they look for new alternatives for energy storage, particularly for stationary grid storage."