Abstract

Aqueous halide-based redox flow batteries are a promising solution for large-scale energy storage, but their performance has been limited by phase separation, membrane crossover, and capacity fade. These issues stem from the fundamental thermodynamics of polyhalide speciation in aqueous media. In this talk, I will present a simple yet powerful molecular strategy based on soft-hard zwitterionic trappers (SH-ZITs) that addresses these challenges. Guided by soft-hard acid-base theory, SH-ZITs combine a soft organic cation to stabilize polyhalide anions and a hard anionic group to ensure water solubility and membrane selectivity. This molecular design shifts the thermodynamic equilibrium toward stable, homogeneous polyhalide complexes without relying on strong covalent interactions. As a result, we demonstrate redox flow battery catholytes with capacities exceeding 100 Ah per liter, coulombic efficiencies above 99.9 percent, and stable cycling at up to 90 percent state of charge. This work shows how thermodynamic principles can be harnessed through simple chemistry to enable high-performance energy storage systems.

Biography

Dawei Feng is an Assistant Professor at University of Wisconsin-Madison in the Department of Materials Science and Engineering with an affiliation in the Department of Chemistry. He received his B.S. and Ph.D. in Chemistry from Peking University and Texas A&M University respectively and did his postdoctoral training at Stanford University. His research interests are redox active materials and ion conductive materials design and synthesis and currently focusing on redox flow batteries for grid energy storage. Dawei is a recipient of ACS Inorganic Chemistry Young Investigator and the NSF CAREER award.