The electrode temperature distribution of a solid oxide fuel cell (SOFC) is an important parameter to consider for gaining better insight into the cell performance and its temperature-related degradations. The present efforts of measuring gas channel temperatures do not accurately reveal the cell surface temperature distribution. Therefore, the authors propose a cell-integrated multi-junction thermocouple array to measure the electrode temperature distribution from a SOFC. In this work, the authors deposited a thin film multi-thermocouple array on the cathode of a commercial SOFC and, the temperature of the cell was measured under varying fuel compositions of hydrogen and nitrogen. The multi-thermocouple array showed excellent temperature correlation with the fuel flow rate and with the cell’s performance whilst commercial thermocouples showed a very dull response. Further, cell temperature measurements via the multi-thermocouple array enabled detecting potential fuel crossover. This diagnostic approach is applied to commercial SOFCs, yielding insights into key degradation modes including gas-leakage induced temperature instability, its relation to the theoretical OCV and current output, and propagation of structural degradation. It is envisaged that the use of the multi-thermocouple array technique will lead to major improvements in the design of electrochemical energy devices, like FC and batteries and their safety features, and other hard-to-reach devices such as inside an internal combustion engine or turbine blades.
Keywords solid oxide fuel cells, cathode temperature of SOFC, thin-film thermocouples, multi-thermocouple array, fuel flowrate-OCV relationship