Local electrochemical and thermal investigation of a segmented reversible solid oxide fuel cell and electrolyzer

A novel setup has been designed and mounted to investigate the local electrochemical and thermal behavior of a cell from a 4-cell short stack under reversible operation solid oxide fuel cell/solid oxide electrolyzer (SOFC/SOE). It consists in the partition of the cell's oxygen electrode into 20 segments, where each segment is controlled by a specific electronic load. This allows to control the segments independently in galvanostatic or potentiostatic mode. The configuration also enables local electrochemical impedance spectroscopy (EIS) measurements of each segment. 20 thermocouples were added to measure the local temperature of the segments in order to gain a deeper insight into the cell thermal distribution. This helps correlating the local thermal and electrochemical responses to the operating parameters. This specific setup allowed mapping the cell's local behavior based on a multidimensional operating conditions matrix, including current density, temperature, feed gas composition, sweep gas flow and polarization. Moreover, a durability test of more than 1,000 h helped investigating the local long-term degradation in a reversible (day SOE, night SOFC) configuration. These results are of significant importance towards optimal operation of a reversible SOC with enhanced durability.