Electrolyte layer gas triggers cathode potential instability in CO2 electrolyzers
By Krause, Kevin; Lee, Jason K.; Lee, ChungHyuk; Shafaque, Hisan W.; Kim, Pascal J.; Fahy, Kieran F.; Shrestha, Pranay; LaManna, Jacob M.; Baltic, Elias; Jacobson, David L.; Hussey, Daniel S.; Bazylak, Aimy
Published in Journal of Power Sources
2022
Abstract
Electrolytic carbon dioxide (CO2) reduction is becoming increasingly promising for managing anthropogenic CO2 emissions; however, issues related to unstable performance and ineffective gas management are still not fully accounted for in the field. Here, we identify two instability modes that are directly linked to the electrolyte layer gas saturation for an anion exchange membrane CO2 reduction flow cell circulating a neutral pH electrolyte (KHCO3). The cathode potential exhibits a semi-stable mode with low electrolyte layer gas saturations and a detrimental secondary mode with high gas saturations and a highly noisy, non-stationary potential. We illustrate that the gas saturation has a profound, direct impact on the mode of instability with a direct correlation between the coefficient of variation in cathode potential and the electrolyte layer gas saturation measured with real-time neutron radiography. This correlation is indicative of reaction site gas blockage that results in performance instability and reduced energy efficiency.