Advanced Analytical Techniques for the Study of Energy Conversion and Storage

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Thursday, June 9, 2022 1:00 pm EST
Organizer: Nicola Menegazzo and Jaejin Kim

The shift to a low carbon economy will require wide-scale deployment of energy conversion and storage technologies. Breakthroughs in materials will enable batteries with higher capacities and cycle life leading to larger integration of renewable sources (wind and solar PV) while novel electrocatalysis will provide carbon-neutral fuels for sectors that are difficult to decarbonize with batteries alone, like heavy-duty transport. Analytical chemistry plays a central role in understanding the composition, structure and performance of the materials that will drive the energy transition. In this symposium we will present recent advances in in-situ and -operando analytical techniques used to study materials and electrochemical processes under operationally relevant conditions, thereby gaining insights into the fundamental phenomena that impact their function and behavior.

Presentation 1
Development and Application of In Situ Magnetic Resonance Methods for Studying Redox Flow Batteries
Evan Wenbo Zhao, Radboud University
Large-scale energy storage is becoming increasingly critical to balancing renewable energy production and consumption. Organic redox flow batteries, made from inexpensive and sustainable redox-active materials, are promising storage technologies that are cheaper and less environmentally hazardous than vanadium-based batteries, but they have shorter lifetimes and lower energy density. Thus, fundamental insight at the molecular level is required to improve performance. In this talk, I will present in situ nuclear magnetic resonance (NMR), magnetic resonance imaging (MRI) and electron paramagnetic resonance (EPR) methods for studying redox flow batteries, which are applied to a redox-active molecule: 2,6-dihydroxyanthraquinone (DHAQ). I will discuss how these methods allow a large range of chemical and physical phenomena to be identified and quantified, including reaction intermediate and product, intermolecular electron transfer, solvent distribution, and electrolyte degradation.[1-2] These fundamental insights motivated the development of a simple and low-cost method for measuring the state-of-charge of a flow battery. Furthermore, through in situ monitoring, electrochemical back-conversion of the degradation products to DHAQ has been observed in real time, leading to the development of an electrochemical regeneration method that prolongs the lifetime of anthraquinone-based redox flow batteries substantially.[3] In the end, I will present future plans for next-generation in situ NMR method development. 1. Zhao, E. W. et al. “In situ NMR metrology reveals reaction mechanisms in redox flow batteries” Nature 2020, 579, 224. 2. Zhao, E. W. et al. “Coupled in situ NMR and EPR studies reveal the electron transfer rate and electrolyte decomposition in redox flow batteries” J. Am. Chem. Soc. 2021, 143, 1885. 3. Jing, Y. et al. “Electrochemical regeneration of anthraquinones for lifetime extension in flow batteries” ChemRxiv (DOI:10.33774/chemrxiv-2021-x05x1)

Presentation 2
A Live View on Electrocatalysis using Operando XPS
Rik V. Mom
: In search of molecular-level understanding of electrochemical reactions, insight into the chemical state of the electrode-electrolyte interface is an essential component. In this talk, I will show how X-ray photoelectron spectroscopy (XPS) can help to obtain such information. Traditionally, XPS is a vacuum-based technique that can only provide a detailed chemical analysis before or after electrochemistry. However, advanced spectro-electrochemical cell design now makes it possible to interface the vacuum needed for XPS with wet electrochemical environments, enabling us to study the electrode-electrolyte interface during electrocatalytic reactions. I will exemplify the capabilities of operando XPS using case studies related to fuel cells and electrolyzers: 1) The oxidation of platinum during simulated fuel cell start-up, 2) the surface structure of iridium and ruthenium oxides during the oxygen evolution reaction, and 3) the behavior of ions near ruthenium oxide and graphene electrodes. These examples highlight the possibilities for quantifying the interface composition of active electrochemical systems, both on the electrode and electrolyte side. Finally, I will give a perspective on how to bring operando XPS from the synchrotron to the laboratory, which will be an important step towards widespread implementation of the technology.

Presentation 3
Understanding Solid Electrolyte-lithium Interfaces via Operando Multiscale Characterizations
Yan Yao, University of Houston
The complex origins of solid-state battery failure call for multidimensional diagnostics utilizing a combination of tools that can quantify the void and dendrite formation, identify the chemical and mechanical natures of the Li dendrites and electrolyte decomposition products. However, there is lack of tools that connect multiple techniques with desirable length scale, resolution and sensitivity for characterizing solid-state batteries. The objective of this talk is to develop an air-free vessel with an in-situ cell test platform connecting FIB-SEM tomography, ToF-SIMS, and in-SEM nanoindentation for structural, chemical, and mechanical characterizations of solid-state Li batteries. We fabricated solid-state micro-cells with electrochemical performance on par with their bulk-type counterparts. Electrochemical tests with precise temperature control, external pressure, and pressure monitoring of thin solid-state cells were demonstrated with structural, chemical and mechanical characterizations.

Presentation 4
Multi-modal Analysis of Battery Chemistries using Raman Spectroscopy Coupled to Scanning Electrochemical Microscopy (Raman-SECM): Sensing Processes Within, Over, and Above Electrodes
Joaquin Rodriguez Lopez, University of Illinois Urbana-Champaign
Electrochemical energy storage technologies such as non-aqueous redox flow batteries (NRFBs), Li-ion batteries, and battery chemistries beyond Li, while showing promise for their energy density, present manifold challenges regarding performance and lifetime which currently limit their widespread adoption. Understanding the relationship between structural/chemical degradation and electrochemical performance is key to predict the failure mechanisms of batteries. In this presentation, we will discuss how we have combined the redox imaging capabilities of scanning electrochemical microscopy (SECM) with Raman spectroscopy into a simultaneous, co-localized, in situ and real-time analytical platform to detect degradation processes in battery electrodes. These studies can be performed on electrodes, and in the vicinity of the diffusion layer, providing a powerful method to probe degradation processes occurring in different regions of interest at the electrochemical interface. We will focus on the use of Raman-SECM to characterize the degradation mechanism of a redox-active catholyte intended for non-aqueous redox flow batteries: 2,3-dimethyl-1,4-dialkoxybenzene (C7).[1] Co-alignment of an ultramicroelectrode (UME) SECM probe to the Raman laser line allowed us to detect in situ the generation of the charged form of C7. Addition of a Lewis base to the solution allowed us to quantify the rate of deprotonation of these species while simultaneously observing its Raman signatures as we obtained approach curves. We hope these new analytical capabilities will help inform strategies to extend the lifetime of molecules in solution and interfaces for better performing batteries. [1] Watkins, T.; Sarbapalli, D.; Counihan, M.J.; Danis, A.S.; Zhang, J.; Zhang, L.; Zavadil, K.R.; Rodríguez-López, J. J. Mater. Chem. A. 2020, 8, 15734-15745.

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