A Reversible Protonic Ceramic Cell with Symmetrically Designed Pr₂NiO_4+δ-Based Electrodes: Fabrication and...

Reversible protonic ceramic cells (rPCCs) have shown potential for dual-mode operation, enabling both fuel cell and electrolysis functions. These systems operate at lower temperatures than traditional solid oxide cells and offer high efficiency. While prior research has demonstrated the feasibility of rPCCs, the fabrication of symmetrical electrodes in a single step remains a challenge. Existing studies often rely on multiple sintering processes or asymmetric electrode designs. The hydration behavior of electrode materials under different atmospheres is not fully understood. This gap motivated the investigation of symmetrical Pr₂NiO₄+δ-based electrodes. The study aimed to explore how water vapor partial pressure affects electrode performance. No prior work had resolved the impact of hydration on mixed-ionic/electronic conductivity in such systems. This research addresses the need for simpler fabrication methods and improved understanding of electrode behavior under varying humidity. The findings may contribute to optimizing rPCCs for practical applications.

The study aimed to develop a reversible protonic ceramic cell (rPCC) using symmetrical Pr₂NiO₄+δ-based electrodes fabricated in a single sintering step. The researchers sought to evaluate the electrochemical performance of the cell under different operating conditions. They focused on understanding how water vapor partial pressure affects electrode behavior. The goal was to assess the impact of hydration on mixed-ionic/electronic conductivity. The team also aimed to compare the efficiency of the fuel cell and electrolysis modes. They investigated the role of the BCZD membrane in improving electrolytic properties. The study sought to determine whether symmetrical electrodes could maintain performance in both modes. The motivation was to simplify fabrication while enhancing operational efficiency.

The researchers fabricated a rPCC using a single sintering step to create symmetrical electrodes. They employed Pr₂NiO₄+δ-based materials modified with Pr₂O₃ and Ni components. The cell structure was P⁻N⁻BCZD|BCZD|PBN⁻BCZD. They conducted volt-ampere measurements to assess current-voltage relationships. Electrochemical impedance spectroscopy was used to analyze resistance and capacitance. Distribution of relaxation times analysis provided insights into electrode kinetics. The experiments were performed at 750 °C under varying water vapor partial pressures. Both reducing and oxidizing atmospheres were tested for electrode behavior. The team compared the performance of fuel cell and electrolysis modes under humidified conditions.

The symmetrical electrodes showed mixed-ionic/electronic conducting behavior but lacked hydration capability at 750 °C. Increasing water vapor partial pressure reduced electrochemical activity in both atmospheres. The BCZD membrane exhibited improved electrolytic properties under humid conditions. Ohmic resistance in the electrolysis mode decreased with higher pH₂O values. This reduction enhanced the efficiency of the electrolysis cell mode. The fuel cell mode performed less effectively under highly humid atmospheres. The researchers observed that hydration negatively affected electrode performance. The electrolysis mode was found to be more suitable for high-humidity environments. These findings suggest that operational conditions significantly influence rPCC performance. The study highlights the importance of membrane properties in determining overall efficiency.

The study demonstrates that symmetrical Pr₂NiO₄+δ-based electrodes can be fabricated in a single sintering step. These electrodes exhibit mixed-ionic/electronic conductivity but show no hydration capability at 750 °C. The researchers found that increasing water vapor partial pressure reduces electrode activity in both atmospheres. The BCZD membrane contributes to improved electrolytic performance under humid conditions. The electrolysis mode outperforms the fuel cell mode in highly humid environments. This is due to the reduction in ohmic resistance with higher pH₂O values. The study supports the use of symmetrical electrodes for rPCCs. The findings suggest that operational conditions significantly affect rPCC efficiency. The authors propose that membrane properties play a key role in determining performance. They suggest that further research could explore alternative materials for improved hydration behavior.