Abstract

Magnetic resonance methods, including nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR), are non-invasive, atom-specific, quantitative, and are applicable for liquid and solid-state materials. These features make magnetic resonance ideal tools for operando measurement of an electrochemical device, and for establishing structure-function relationships under device-operating conditions. 

For the first part of my talk, I will present how we develop and apply coupled (benchtop) NMR and EPR methods to unravel molecular-level physical and chemical processes in redox flow batteries. I will present case studies on anthraquinone, viologen and copper-based RFBs and demonstrate how we monitor the state of charge, unravel degradation reaction mechanisms as well as ion transport through membranes. For the second part, I will present new in situ NMR methods for studying Li-mediated ammonia synthesis, and the direct observation of lithium plating and its concurrent corrosion, nitrogen splitting on lithium metal and protonolysis of lithium nitride. Built upon these insights, we have developed a new alkaline electrochemical ammonia synthetic method. By the end of this talk, I hope to show that operando magnetic resonance is powerful and general, and can be applied for understanding various energy storage and conversion chemistries. 

References

1. Zhao E W, Liu T, Jónsson E, Lee J, Temprano I, Jethwa B J, Wang A, Smith H, Carretero-González J, Song Q, Grey C P “In situ NMR metrology reveals reaction mechanisms in redox flow batteries” Nature 2020, 579, 224-228.
2. Tan R, Wang A, Malpass-Evans R, Williams R, Zhao E W, Liu T, Ye C, Zhou X, Darwich B P, Fan Z, Turcani L, Jackson E, Chen L, Li T, Jelfs K E, Cooper A I, Brandon N P, Grey C P, McKeown N B, Song Q “Hydrophilic microporous membranes for selective ion separation and flow-battery energy storage” Nature Materials 2020, 19, 195-202.
3. Jing Y, Zhao E W, Goulet M A, Bahari M, Fell E, Jin S, Davoodi A, Jónsson E, Wu M, Grey C P, Gordon R, D, Aziz M “In situ electrochemical recomposition of decomposed redox-active species in aqueous organic flow batteries” Nature Chemistry 2022, 14, 1103-1109.
4. Luo R, Janssen H J W G, Kentgens A P M, Zhao E W “A parallel line probe for spatially selective electrochemical NMR spectroscopy” J. Magn. Reson. 2024, 361, 107666 (Front cover; Special Issue: New Voices in Magnetic Resonance; Invited).
5. Luo R, Gunnarsdóttir A B, Aspers R L E G, Zhao E W “In situ NMR guided design of alkaline electrochemical ammonia synthesis” Science Advances, Accepted.

Biography

Evan Zhao is an assistant professor at the Magnetic Resonance Research Center, Radboud University in the Netherlands. He did his postdoc at University of Cambridge, PhD at University of Florida and Bachelor study at Nanyang Technological University. He has been developing operando magnetic resonance for understanding redox flow batteries and electrochemical conversion. Evan has been recently awarded the ECS Toyota Young Investigator Fellowship.