Advancements regarding in-operando diagnosis techniques for solid oxide cells NiYSZ cermets

Solid Oxide Cell (SOC) is a promising technology, featuring versatile applications from combined heat and power generation to power-to-gas storage. Whilst their commercial readiness is poor, their advantages in terms of efficiency and environmental sustainability are undeniable. However, lifetime is an overriding concern. In the normal practice, in-operando experimental investigation of degradation is performed through volt-amperometric measurements and electrochemical impedance spectroscopy. Despite their implementation simplicity, it is hard to correlate the measurements output with the corresponding chemical/physical change at the microscopic scale. Ex-situ analysis on exhausted materials partially answers this question. Conversely, in-situ and in-operando material analysis provides insight on processes occurring during operating cycles (i.e. temperature range 650-900°C, pressure at least atmospheric, electrodes exposure to flammable gases, electric current flow across the membrane-electrodes assembly). Many techniques are available to this matter, yet their implementation usually results challenging. This review aims at presenting the advantages of in-situ and in-operando diagnosis techniques for the detection of specific degradation mechanisms affecting SOC cermets.