Distinguished Seminar: “High-Voltage Membrane-Free Redox Flow Batteries”

Short Bio

Jianbing “Jimmy” Jiang
Dr. Jimmy Jiang is now an Associate Professor in the Department of Chemistry at the University of Cincinnati. He earned his B.S. from Jiangnan University in 2007 and M.S. from East China University of Science and Technology in 2010. He obtained his Ph.D. from North Carolina State University (advisor: Jonathan Lindsey) working on tetrapyrrole compounds for energy applications. In 2015, he joined Yale University as a Postdoctoral Associate and then an Associate Research Scientist in the Department of Chemistry and Yale Energy Sciences Institute, working with Professors Gary Brudvig and Robert Crabtree on organometallic materials for small molecule activation and energy storage. Jimmy started his independent career as an Assistant Professor in the Department of Chemistry at the University of Cincinnati in 2018 and was tenured in 2022. He received the NSF CAREER award in 2021, and was named an Alfred P. Sloan Fellow in 2022.

Abstract

High-Voltage Membrane-Free Redox Flow Batteries

While membrane-free batteries have been successfully demonstrated in static batteries, membrane-free batteries in authentic flow modes with high energy capacity and high cyclability are rarely reported. To broaden the electrochemical window of the biphasic electrolyte, the aqueous phase was replaced with a nonaqueous phase to construct nonaqueous/nonaqueous biphasic and triphasic electrolytes. In the biphasic approach, an immiscible nonaqueous electrolyte setup is formed with two distinct electrolyte phases: 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMP-TFSI) with LiTFSI as the anolyte and fluoroethylene carbonate (FEC) with LiTFSI as the catholyte. This configuration enables phase separation. Biphasic cells show promise for achieving high-voltage stability and moderate energy densities, but encounter issues with capacity retention over extended cycling due to the interfacial limitations. In contrast, the triphasic system introduces a third electrolyte layer (NFTTS) between the anolyte and catholyte phases, significantly improving the performance by acting as an ion-selective barrier. The triphasic electrolyte layer overcomes some of the limitations of biphasic setups by preventing self-discharge and reducing the interfacial instability. This layer is particularly beneficial under dynamic (flow) conditions as it enhances the Coulombic efficiency and capacity retention, where near-100% efficiency was observed under static and flow conditions. This triphasic setup demonstrated high compatibility with lithium-metal anodes, achieving high Coulombic and energy efficiency during extensive cycling, demonstrating the enhanced potential of membrane-free triphasic RFBs over biphasic configurations.