CO electrolysis (COE) has emerged as an important alternative technology to couple with other sustainable techniques for transitioning towards a carbon-neutral future. A large challenge for the deployment of high-rate COE is the limited durability of membrane-electrode assembly (MEA) devices. Here, by using an operando wide-angle X-ray scattering technique and monitoring the change of electrolyte, we identified several degradation mechanisms of the MEA during high-rate COE. Cathodic gas-diffusion electrode (GDE) flooding and Ir contaminants (crossover from anode) are two main issues causing excessive hydrogen evolution, which can be partly alleviated by increasing the polytetrafluoroethylene content in GDEs and using an alkaline stable Ni-based anode. During long-term stability, the dynamic evolution of anolyte became the main issue: the pH would continuously drop due to cathodic acetate formation and anodic ethanol oxidation. By compensating for this issue, we maintained a Faradaic efficiency of C₂₊ products at more than 70% for 136 hours.

二氧化碳电解（COE）已成为一种重要的替代技术，可与其他可持续技术相结合，以实现向碳中和的未来过渡。高倍率 COE 部署的一大挑战是膜电极组件 (MEA) 装置的耐用性有限。在这里，通过使用操作广角 X 射线散射技术并监测电解质的变化，我们确定了高倍率 COE 期间 MEA 的几种降解机制。阴极气体扩散电极 (GDE) 溢流和 Ir 污染物（从阳极穿过）是导致过量析氢的两个主要问题，可以通过增加 GDE 中的聚四氟乙烯含量和使用碱性稳定的镍基阳极来部分缓解这一问题。在长期稳定过程中，阳极电解液的动态演化成为主要问题：由于阴极乙酸盐的形成和阳极乙醇的氧化，pH 值会持续下降。通过补偿这个问题，我们保持了 C 的法拉第效率₂₊产品持续 136 小时电量超过 70%。