Quantifying individual electrode polarization and unraveling the interactive phenomenon in solid oxide fuel cells

In electrochemically active systems, such as fuel cells, electrolyzers, and batteries, researchers often modify the material chemistry or operating variables at one of the electrodes (e.g., the cathode) to investigate its properties. This approach assumes that changes in measured polarization and cell performance result solely from the modifications made to the selected electrode, while the conditions at the other electrode (e.g., the anode) remain constant. However, the potential interactions between the polarizations of these two electrodes have remained unclear. In our study, we utilize a voltage probe capable of precisely determining electrode polarization. Our findings reveal three key insights: 1. The quantification of electrode polarization becomes feasible through the implementation of a voltage probe. 2. The fuel electrode plays a pivotal role in the performance of state-of-the-art solid oxide cells, with its influence being comparable to that of the oxygen electrode. 3. A reciprocal interaction exists between the two electrodes within a solid oxide cell. Consequently, when there are changes in the chemistry or operational conditions at one electrode, the polarization of the other electrode changes simultaneously.