Quantifying concentration distributions in redox flow batteries with neutron radiography.

The continued advancement of electrochemical technologies requires an increasingly detailed understanding of the microscopic processes that control their performance, inspiring the development of new multi-modal diagnostic techniques. Here, we introduce a neutron imaging approach to enable the quantification of spatial and temporal variations in species concentrations within an operating redox flow cell. Specifically, we leverage the high attenuation of redox-active organic materials (high hydrogen content) and supporting electrolytes (boron-containing) in solution and perform subtractive neutron imaging of active species and supporting electrolyte.

A versatile optimization framework for porous electrode design.

Porous electrodes are performance-defining components in electrochemical devices, such as redox flow batteries, as they govern the electrochemical performance and pumping demands of the reactor. Yet, conventional porous electrodes used in redox flow batteries are not tailored to sustain convection-enhanced electrochemical reactions. Thus, there is a need for electrode optimization to enhance the system performance.

Engineering Lung-Inspired Flow Field Geometries for Electrochemical Flow Cells with Stereolithography 3D Printing.

Electrochemical flow reactors are increasingly relevant platforms in emerging sustainable energy conversion and storage technologies. As a prominent example, redox flow batteries, a well-suited technology for large energy storage if the costs can be significantly reduced, leverage electrochemical reactors as power converting units. Within the reactor, the flow field geometry determines the electrolyte pumping power required, mass transport rates, and overall cell performance.

When Flooding Is Not Catastrophic-Woven Gas Diffusion Electrodes Enable Stable CO Electrolysis.

Electrochemical CO reduction has the potential to use excess renewable electricity to produce hydrocarbon chemicals and fuels. Gas diffusion electrodes (GDEs) allow overcoming the limitations of CO mass transfer but are sensitive to flooding from (hydrostatic) pressure differences, which inhibits upscaling. We investigate the effect of the flooding behavior on the CO reduction performance.

Taurine Electrografting onto Porous Electrodes Improves Redox Flow Battery Performance.

The surface properties of porous carbonaceous electrodes govern the performance, durability, and ultimately the cost of redox flow batteries (RFBs). State-of-the-art carbon fiber-based electrode interfaces suffer from limited kinetic activity and incomplete wettability, fundamentally limiting the performance. Surface treatments for electrodes such as thermal and acid activation are a common practice to make them more suitable for aqueous RFBs; however, these treatments offer limited control over the desired functional properties.

Narrow Pressure Stability Window of Gas Diffusion Electrodes Limits the Scale-Up of CO Electrolyzers.

Electrochemical CO reduction is a promising process to store intermittent renewable energy in the form of chemical bonds and to meet the demand for hydrocarbon chemicals without relying on fossil fuels. Researchers in the field have used gas diffusion electrodes (GDEs) to supply CO to the catalyst layer from the gas phase. This approach allows us to bypass mass transfer limitations imposed by the limited solubility and diffusion of CO in the liquid phase at a laboratory scale.

Non-Solvent Induced Phase Separation Enables Designer Redox Flow Battery Electrodes.

Porous carbonaceous electrodes are performance-defining components in redox flow batteries (RFBs), where their properties impact the efficiency, cost, and durability of the system. The overarching challenge is to simultaneously fulfill multiple seemingly contradictory requirements-i.e.

Investigating Electrode Flooding in a Flowing Electrolyte, Gas-Fed Carbon Dioxide Electrolyzer.

Managing the gas-liquid interface within gas-diffusion electrodes (GDEs) is key to maintaining high product selectivities in carbon dioxide electroreduction. By screening silver-catalyzed GDEs over a range of applied current densities, an inverse correlation was observed between carbon monoxide selectivity and the electrochemical double-layer capacitance, a proxy for wetted electrode area. Plotting current-dependent performance as a function of cumulative charge led to data collapse onto a single sigmoidal curve indicating that the passage of faradaic current accelerates flooding.

Elucidating the Nuanced Effects of Thermal Pretreatment on Carbon Paper Electrodes for Vanadium Redox Flow Batteries.

Sluggish vanadium reaction rates on the porous carbon electrodes typically used in redox flow batteries have prompted research into pretreatment strategies, most notably thermal oxidation, to improve performance. While effective, these approaches have nuanced and complex effects on electrode characteristics hampering the development of explicit structure-function relations that enable quantitative correlation between specific properties and overall electrochemical performance. Here, we seek to resolve these relationships through rigorous analysis of thermally pretreated SGL 29AA carbon paper electrodes using a suite of electrochemical, microscopic, and spectroscopic techniques and culminating in full cell testing.

Engineered Water Highways in Fuel Cells: Radiation Grafting of Gas Diffusion Layers.

A novel method to produce gas diffusion layers with patterned wettability for fuel cells is presented. The local irradiation and subsequent grafting permits full design flexibility and wettability tuning, while modifying throughout the whole material thickness. These water highways have improved operando performance due to an optimized water management inside the cells.