The last decade reveals the high potential of Solid oxide cells (SOC) as hydrogen battery storage operating to the demand either under fuel cell (concept gas-to-power) or electrolysis (concept power-to-gas) profiles. Such types of ceramic-based cells usually operate beyond 750°C in order to keep reasonable electrical performances and reliability of the whole electrochemical device. Now, one of the main challenge is to reduce the operating temperature in order to limit ageing parameters (Cr contamination, metal corrosion…) and improve energy efficiency while promoting cheaper materials and system processing. Actually, O₂^--conducting SOC suffers to an insufficient activity of the oxygen electrode and electrical performances at lower operation temperature.

In such context, Protonic Ceramic Cell (PCC) technology can overcome such technical hurdle by operating below 700°C. Protonic Ceramic Cells are benefit from the presence of the water produced/consumed at the air electrode side, avoiding the dilution of the fuel. The ageing and chemical reactivity of materials should be less critical than these observed at higher temperature. Proton Conducting Ceramic Cell is now widely investigated for a variety of applications, in particular fuel cell, steam electrolysis and hydrogen separation but such technology has to face to the lack of Technology Readiness Level (operating parameters definition, durability, dimensioning) for a viable way of market.

During the last years, our group validated promising pioneer promising electrical performances (400-500 mW.cm²) and reliability of few hundred hours under dynamic fuel cell power demand profile below 700°C ^[1-3]. Here is discussed the evaluation of advanced PCC materials and manufacturing processes under electrolysis and reversible Fuel cell / electrolysis cycles modes. Finally, more than 3500 h of long-term testing were validated under various function profiles (as electricity producer or as hydrogen producer) with limited electrical degradation (cf. Figure 1). Such highlights pave the way to the use of PCC technology as high efficient energy storage candidate .