Abstract

The synergy of macromolecular redoxmer architectures with size-exclusion separation approaches enable new operation strategies for nonaqueous redox flow batteries (NRFBs) [1], which despite their promising energy density are underdeveloped in comparison to their aqueous counterparts. The polyelectrolytic nature of these redoxmers [3] (i.e., redox-active oligomers, polymers, and colloids) leads to complex electrochemical behavior. Thus, building a new toolbox that permits the characterization and leveraging of these properties from single particles to interfaces to fluids is full of opportunities.

In this talk, I will first describe how we have leveraged the versatility of macromolecular design to advance their functioning. I will then highlight recent works in our laboratories regarding 1) redoxmer dynamics [2], 2) end-of-life [3], and 3) high-throughput testing considerations [4]. In the first case, I will report on how systematic design of redoxmers focusing on polymers with pendants consisting of redox moieties with different self-exchange rate modulates their limiting current at an electrode. For these polymeric redoxmers interfacial conformation as a function of ionic strength [3] has a profound impact on their analytical responses, which then translate to observed trends in battery cycling tests. Unfortunately, decomposition of these redoxmers following extended cycling is still a reality. To address these issues, we have proposed that redoxmers should incorporate end-of-life considerations. To this point, we explored the electrochemistry of redoxmers build on redox-active homobenzylic ether (HBE) backbones that could be depolymerized on-demand should deteriorating events occur. These end-of-life functions could be used for multiple purposes such as for the regeneration of electrodes affected by passivating redoxmer films, or for the recovery and recycling of redoxmers with decreased charge transport capacity. Finally, addressing redoxmer transport, kinetics, and the conditions that lead to their degradation requires an integrated toolset capable of offering this information promptly. In the last highlight, I will introduce novel multiplexed electrode designs that systematically address these stated needs using a modern microelectrode approach coupled with microfluidics. These new devices enable the user to perform otherwise tedious operations during characterization in an automated and systematic manner, enabling the high-throughput processing of redox materials.  References: [1] Acc. Chem. Res. 2016, 49, 2649-2657.  [2] J. Am. Chem. Soc. 2018, 140, 2093-2104.  [3] J. Mater. Chem. A 2022, 10, 7739-7753.   [4] ACS Measurement Science Au 2022, ASAP.

Biography

Joaquín Rodríguez-López is an associate professor in the Department of Chemistry at the University of Illinois Urbana-Champaign. He did his undergraduate studies at Tecnológico de Monterrey, where he performed research in electrochemistry with Prof. Marcelo Videa (2005). He then moved to nearby Texas to obtain a Ph.D. under the guidance of Prof. Allen J. Bard at the University of Texas at Austin (2010). He performed postdoctoral studies with Prof. Hector D. Abruña in Cornell University (2012). Joaquin’s group combines interests in electroanalytical chemistry and energy materials by developing chemically-sensitive methods for studying ionic and electronic reactivity in nano-structures, highly-localized surface features, and ultra-thin electrodes. Joaquin’s group aspires to build a dynamic and diverse environment for research that generates original concepts for high-performance energy technologies.

Seminar sponsored by the Department of Chemistry and Biochemistry