Hydrogen technologies are revolutionizing the energy landscape, offering a sustainable alternative to fossil fuels. With zero emissions and versatile applications, hydrogen fuels promise to decarbonize industries like transportation and power generation. Their scalability and potential to store renewable energy make them crucial in the transition to a cleaner and greener future. Among different technologies, Solid Oxide Cells (SOCs) have unrivaled conversion efficiencies in order to produce hydrogen as fuel by electrochemical conversion of water [1]. In addition, they are the most clean technology with dual functionality, as the ceramic device can work reversibly and convert the chemical energy of hydrogen fuel to electricity [2]. Thus, there has been a rapid development of SOC technologies over the last decade with significant advantages and progress in key issues such as materials, performance, degradation and stack design.

In this work, a 5 x5 cm² fuel electrode-supported solid oxide cells was self-fabricated by aqueous-based tape casting in conjunction with co-sintering and screen printing, taking advantage of its cheapness, scalability and capability of reaching an electrolyte of reduced thickness (12 μm). The mass transport limitation due to the use of a thick supporting H₂ electrode (~ 350 μm) was offset using a pore former in order to increase the porosity of the electrode. Between the porous support and the electrolyte, a functional layer of 50 μm thickness was added. Standard materials were chosen for each component: yttria stabilized zirconia (YSZ) as the electrolyte, Ni-YSZ cermet as the fuel electrode and lanthanum strontium manganite (LSM)-YSZ or Lanthanum strontium cobalt ferrite (LSCF)-gadolinium doped ceria (GDC) (including a GDC buffer layer) composites as the air electrode. Tape-casting, screen printing and sintering parameters were optimized in order to obtain reproducible and highly flat cells with homogeneous thickness. SEM was employed to carefully inspect the microstructure of the different components.

The electrochemical characterization of the SOCs was carried out by means of Electrochemical Impedance Spectroscopy (EIS) and current-voltage curves analysis. The cells performance was evaluated in both fuel cell (SOFC) and electrolysis (SOEC) modes. The effect of the oxygen partial pressure and the humidity was studied at 800 °C. Current densities of approximately -1 A·cm^-2 at 1.3 V were achieved in electrolysis mode, with consistent reproducibility over multiple cells. Cells mechanical stability was confirmed by a post-mortem SEM study.

In conclusion, reproducible planar SOCs with large area were fabricated, exhibiting an electrochemical performance comparable to standard cells produced by other manufactures. These results pave the way for the development of a scalable process with the objective of designing and fabricating a stack prototype.