The transportation industry is one of the largest consumers of energy in the U.S., with increasing demand to make it cleaner and more efficient. While more people are using electric cars, when it comes to designing electric-powered planes, ships, and submarines, it is much more difficult due to power and energy requirements.
But, a team of engineers in the McKelvey School of Engineering at Washington University in St. Louis may have come up with a solution. The team developed a high-power fuel cell that advances technology in this area. The direct borohydride fuel cell operates at double the voltage of today’s commercial fuel cells.
This advancement uses a unique pH-gradient-enabled microscale bipolar interface (PMBI) and has the potential to power a variety of transportation modes — including unmanned underwater vehicles, drones and eventually electric aircraft — aa t significantly lower cost.
“The pH-gradient-enabled microscale bipolar interface is at the heart of this technology,” said Vijay Ramani, the Roma B. and Raymond H. Wittcoff Distinguished University Professor, 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 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. According to Ramani, 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.
“Previous attempts to achieve this kind of acid-alkali separation were not able to synthesize and fully characterize the pH gradient across the PMBI,” said Shrihari Sankarasubramanian, a research scientist on Ramani’s team. “Using a novel electrode design in conjunction with electroanalytical techniques, we were able to unequivocally show that the acid and alkali remain separated.”
After the PBMI synthesized using the novel membranes and worked effectively the team optimized the fuel cell device and identified optimal operating conditions to achieve a high-performance fuel cell.
The team is hopeful about the technology and is ready to move on to scaling it up for applications in submersibles and drones.