CO₂ electrolysis is a promising carbon utilization technology. Currently, energetic efficiency still requires a significant improvement for commercialization. To rationally design a more efficient CO₂ electrolyzer, diagnostic tools are necessary to pinpoint the source of voltage losses across the full cell at work. Here we develop a five-electrode technique to probe voltage drops at the cathode, anode, membrane, and their interfaces in a typical zero-gap cell. We show that the cathode/membrane ionic interface is the major source of overpotential, contributing 720 mV voltage loss at 600 mA cm^–2. This loss can be mitigated by coating the catalyst directly onto the membrane to lower ionic resistances, reducing this voltage loss to 80 mV at the same current density. The improved design enables us to achieve a full cell performance of 3.55 V and >95% CO Faradaic efficiency at 800 mA cm^–2, representing the highest performance for CO₂ electrolysis with a dilute bicarbonate electrolyte. The insights provided by the five-electrode technique may guide the rational design of future membrane-based electrochemical cells.

中文翻译：

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使用五电极技术诊断 CO2 电解槽中的电压损失

CO ₂电解是一种很有前途的碳利用技术。目前，能量效率仍然需要显着提高才能实现商业化。为了合理地设计更高效的 CO ₂电解槽，需要诊断工具来查明工作中整个电池的电压损失来源。在这里，我们开发了一种五电极技术来探测典型零间隙电池中阴极、阳极、膜及其界面的电压降。我们表明阴极/膜离子界面是过电势的主要来源，在 600 mA cm ^{–2下贡献 720 mV 电压损失}. 这种损失可以通过将催化剂直接涂在膜上以降低离子电阻来减轻，在相同的电流密度下将这种电压损失降低到 80 mV。改进后的设计使我们能够在 800 mA cm ^{–2下实现 3.55 V 的全电池性能和 >95% 的 CO 法拉第效率，代表使用稀碳酸氢盐电解液进行 CO} ₂电解的最高性能。五电极技术提供的见解可能会指导未来基于膜的电化学电池的合理设计。