Direct borohydride fuel cell could take off in electric aircraft

The advance from a team of engineers in the McKelvey School of Engineering at Washington University in St. Louis is reported in Nature Energy.

Led by Vijay Ramani, the Roma B. and Raymond H. Wittcoff Distinguished University Professor, the team’s pH-gradient-enabled microscale bipolar interface (PMBI) could power unmanned underwater vehicles, drones and eventually electric aircraft ‘at significantly lower cost’.

"The pH-gradient-enabled microscale bipolar interface is at the heart of this technology," said Ramani, also professor of energy, environmental & chemical engineering. "It allows us to run this fuel cell with liquid reactants and products in submersibles, in which neutral buoyancy is critical, while also letting us apply it in higher-power applications such as drone flight."

The fuel cell developed at Washington University uses an acidic electrolyte at one electrode and an alkaline electrolyte at the other electrode. Typically, the acid and alkali will quickly react when brought in contact with each other. In a statement, Ramani said the key breakthrough is the PMBI, which is thinner than a strand of human hair. Using membrane technology developed at the McKelvey Engineering School, the PMBI can keep the acid and alkali from mixing, forming a sharp pH gradient and enabling the successful operation of this system.