Authorship：Collaborating Investigator(s) (not designated on Grant-in-Aid) 

Ceramic proton-conducting solid oxide fuel cells and electrolyzers (PCEC/PCFCs) are not just promising technologies; they are the future of sustainable energy generation and storage. The interest in this class of material stems from its high ionic conductivity and inherent advantages in the gas flow configuration over traditional solid oxide cells, in which the electrolyte is an oxygen ion conductor [1]. Despite these many advantages, processing and scaling up such electrolytes for industrial purposes poses several challenges. However, our ongoing research is poised to overcome these challenges and revolutionize the field.
As part of our ongoing international research collaboration between WPI-I2CNER Kyushu University and IEK-1, JUELICH, we have uncovered some truly novel findings. Firstly, we have demonstrated an effective tape-casting route that produces flat, planar protonic electrolysis half-cells with impressive dimensions of up to 100 mm ⅹ 100 mm ⅹ 0.5 mm. The half-cells are constructed using NiO-SrZr0.5Ce0.4Y0.1O3-δ as the substrate, ensuring minimal warping and no cracks in the end-fired state and substantially promoting the half-cell's sintering activity at 1300 °C [2-5]. The electrolyte is gas-tight with a He leakage rate well within the threshold necessary for cell operation (~5 × 10–5 hPa dm3 (s cm2)–1). Secondly, Using Ba0.5La0.5CoO3−δ as the air electrode demonstrates remarkable capabilities and endurance within the 450-600°C temperature range, achieving a power density of 1.0 W cm-2 at 0.7 V in the fuel cell mode and a high current density of 1.5 A cm-2 at 1.3 V in the electrolysis mode while maintaining reasonable Faradaic efficiencies (80-90 %) at 600 oC respectively. Finally, using a combination of SEM-EDX, Raman spectroscopy, and Atom probe tomography, we found that upon sintering above 1350 °C, the electrolyte material undergoes evident structural changes with new defects that affect the perovskite host. These results not only provide new insights but also pave the way for low-cost fabrication of large-sized reversible protonic electrolysis cells.

Authorship：Principal investigator  Grant type：Scientific research funding