Browsing by Subject "redox flow batteries"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Six-electron organic redoxmers for aqueous redox flow batteries
    (Royal Society of Chemistry, 2022-12) Fang, Xiaoting; Cavazos, Andres T.; Li, Zhiguang; Li, Chenzhao; Xie, Jian; Wassall, Stephen R.; Zhang, Lu; Wei, Xiaoliang; Physics, School of Science
    We have developed a novel molecular design that enables six-electron redox activity in fused phenazine-based organic scaffolds. Combined electrochemical and spectroscopic tests successfully confirm the two-step 6e− redox mechanism. This work offers an opportunity for achieving energy-dense redox flow batteries, on condition that the solubility and stability issues are addressed.
  • Thumbnail Image
    Item
    Spatially Constrained Organic Diquat Anolyte for Stable Aqueous Flow Batteries
    (ACS, 2018-09) Huang, Jinhua; Yang, Zheng; Murugesan, Vijayakumar; Walter, Eric; Hollas, Aaron; Pan, Baofei; Assary, Rajeev S.; Shkrob, Ilya A.; Wei, Xiaoliang; Zhang, Zhengcheng; Mechanical Engineering, School of Engineering and Technology
    Redox-active organic materials (ROMs) are becoming increasingly attractive for use in redox flow batteries as promising alternatives to traditional inorganic counterparts. However, the reported ROMs are often accompanied by challenges, including poor solubility and stability. Herein, we demonstrate that the commonly used diquat herbicides, with solubilities of >2 M in aqueous electrolytes, can be used as stable anolyte materials in organic flow batteries. When coupled with a ferrocene-derived catholyte, the flow cells with the diquat anolyte demonstrate long galvanic cycling with high capacity retention. Notably, the mechanistic underpinnings of this remarkable stability are attributed to the improved π-conjugation that originated from the near-planar molecular conformations of the spatially constrained 2,2′-bipyridyl rings, suggesting a viable structural engineering strategy for designing stable organic materials.
  • Thumbnail Image
    Item
    Substituted thiadiazoles as energy-rich anolytes for nonaqueous redox flow cells
    (RSC, 2018-04) Huang, Jinhua; Duan, Wentao; Zhang, Jingjing; Shkrob, Ilya A.; Assary, Rajeev S.; Pan, Baofei; Liao, Chen; Zhang, Zhengcheng; Wei, Xiaoliang; Zhang, Lu; Mechanical Engineering and Energy, School of Engineering and Technology
    Understanding structure–property relationships is essential for designing energy-rich redox active organic molecules (ROMs) for all-organic redox flow batteries. Herein we examine thiadiazole ROMs for storage of negative charge in the flow cells. These versatile molecules have excellent solubility and low redox potentials, allowing high energy density to be achieved. By systematically incorporating groups with varying electron accepting/withdrawing ability, we have examined substituent effects on their properties of interest, including redox potentials, calendar lives of charged ROMs in electrolyte, and the flow cell cycling performance. While the calendar life of energized fluids can be tuned in a predictable fashion over a wide range, the improvements in the calendar life do not automatically translate into the enhanced cycling performance, indicating that in addition to the slow reactions of charged species in the solvent bulk, there are other parasitic reactions that occur only during the electrochemical cycling of the cell and can dramatically affect the cycling lifetime.