Role of the Binder in Mitigating Salt Deposition in 100 cm2 Membrane Electrode Assembly CO2 Electrolyzers

The electrochemical reduction of carbon dioxide offers a promising approach to reduce CO2 emissions while producing valuable chemicals. To date, CO production in membrane electrode assembly (MEA) electrolyzers employing anion exchange membranes results as the most industrially viable setup. However, industrial applicability of this technology is limited by the salt precipitation problem that compromises long-term operation. In this study, we first systematically optimized key electrode components using a 5 cm2 commercial cell and then validated the results in 25 and 100 cm2 electrolyzer under ambient conditions. Among the investigated parameters, the polymeric binder emerges as a critical element influencing both selectivity and stability, due to its impact on salt accumulation. In the 100 cm2 electrolyzer, long-term electrochemical measurements conducted at industrially relevant current density (300 mA cm−2) demonstrate significantly greater stability with PiperION−based cathodes, which maintained faradaic efficiency toward CO larger than 80% for 40 h operations, while Sustainion-based electrodes show a 60% drop after just 20 h. Cross-sectional elemental mapping confirms a direct correlation between the ionomeric binder and Cs salt accumulation in the electrode. This work provides valuable insight into mitigating salt formation and enhancing electrode longevity in large-scale MEA electrolyzers by efficiently tailoring the ionomeric binder.