A synchrotron analysis of high current density CO₂ electrolysis devices

This talk will analyze CO₂ electrolysis from a device perspective to provide insight into what are the bottlenecks in the field and how to resolve them. We will focus on our synchrotron based results using small angle and wide angle x-ray scattering as well as x-ray fluorescence to observe CO₂ electrolysis devices in real time while concomitantly measuring anode and cathode product distributions. During higher current density (>100 mA/cm²) CO₂ electrolysis devices are prone to cathodic ‘flooding’ leading to greatly enhanced hydrogen production. Via our various in-situ analysis tools, we can explain the basis for this flooding, which is primarily due to salt deposition. By analyzing various salts (Li+, Na+, K+, Cs+) of differing solubility we show this trend more clearly. As Cs cations fluoresce, this allows us to show how an applied potential drags these cation salts through an anion exchange membrane, leading to the salt build-up and concomitant deposition in these electrolyzers. As CO electrolysis allows us to switch to more soluble hydroxide salts, we show this is a major key to ensuring long-term stability (>100 hours).