Environmental pollution and resource scarcity have become critical global concerns, driving the urgent need to develop and deploy efficient clean energy technologies. Solid oxide cells (SOCs) represent a highly promising energy conversion device, capable of operating in two modes: as a fuel cell (FC) for efficient, low-emission power generation, and as an electrolysis cell (EC) for high-efficiency hydrogen production. However, commercially available SOCs still face several challenges, including short lifespans due to high operating temperatures (~700 °C), low mechanical strength, and poor thermal shock resistance. In recent years, metal-supported solid oxide cells (MS-SOCs) and protonic ceramic cells (PCCs) have emerged as potential solutions to overcome these limitations and facilitate SOC commercialization.
Combining the advantages of both technologies, the metal-supported reversible protonic ceramic cell (MS-rPCC) offers high mechanical strength, efficient low-temperature operation, improved thermal cycling stability in FC mode, and rapid startup capability. In EC mode, it avoids exposure of the metal support to steam, thereby enhancing electrolysis stability and enabling direct production of dry hydrogen.
However, the development of MS-rPCCs remains significantly constrained by fabrication challenges. Among common metal support materials, stainless steel and other Fe-based alloys are often preferred due to their favorable thermal expansion compatibility. Yet, the high sintering temperatures (>1300 °C) required for dense proton-conducting ceramic electrolytes lead to severe oxidation of stainless steel in conventional co-sintering processes, while alternative techniques such as pulsed laser deposition (PLD) substantially increase manufacturing costs. Furthermore, the diffusion and interfacial reactions of Fe, Mn, and other elements from Fe-based supports with the rPCC components inevitably degrade cell durability. Nickel-based supports, though offering superior catalytic activity, suffer from thermal expansion mismatch with PCCs, compromising structural stability during thermal cycling.
Recently, a research team led by Lichao Jia at Huazhong University of Science and Technology proposed an innovative solution. For the first time, pure nickel was employed as the metal support for reversible protonic ceramic cells, effectively eliminating the diffusion and reaction issues associated with Fe and Mn in conventional supports. Additionally, an engineered transition layer was introduced at the interface to mitigate thermal expansion mismatch between nickel and the PCC, significantly enhancing cell stability. This breakthrough provides a new pathway toward the commercialization of MS-rPCC technology.
The team published their work in Journal of Advanced Ceramics on June 12, 2025.
The use of pure nickel as the support structure effectively eliminates the interfacial diffusion and reaction issues associated with Fe and Mn elements inherent in conventional stainless-steel supports. However, this approach necessitates addressing the thermal expansion coefficient (TEC) mismatch between nickel and other cell components.
To mitigate this TEC mismatch, the researchers proposed an interfacial engineering strategy: the introduction of a transition layer with a thermal expansion coefficient intermediate between that of the nickel support and the fuel electrode. This transition layer accommodates differential dimensional changes among cell components during thermal cycling, thereby enhancing interfacial bonding strength and improving the overall structural stability and electrochemical performance of the cell.
The cell fabricated with an 80 wt.% NiO–20 wt.% BZCY transition layer demonstrated a peak power density of 0.8 W cm-2 in fuel cell mode at 650 °C. In electrolysis mode under 1.3 V and 3% H2O, it achieved a current density of 1.25 A cm-2. These values represent significant improvements over the baseline cell without the transition layer.
Both macroscopic and microscopic morphological analyses confirmed that the transition layer substantially enhanced the cell's structural stability. The engineered interface effectively mitigated thermal stress and interfacial delamination, contributing to the observed performance gains.
Further elemental composition analysis confirmed that the nickel content in each layer of the cell remained highly stable, with no significant diffusion or reaction observed during high-temperature sintering or prolonged operation. The structural design demonstrated excellent durability, as evidenced by stable performance over 200 hours of fuel cell operation and 100 hours of reversible operation (fuel cell/electrolysis cycling).
Moreover, the cell with the engineered transition layer exhibited outstanding thermal cycling stability, with a total performance degradation of only ~2.69% after 5 cycles, corresponding to an average degradation rate of ~0.538% per cycle. In a cold-start test, the cell reached its operating temperature of 600 °C within 60 minutes from room temperature, with the peak power density decreasing only slightly from 0.40 W cm-2 to 0.38 W cm-2, further confirming its robust thermal and structural stability.
However, the performance of the fabricated cell remains limited at lower temperatures, primarily due to the insufficient catalytic activity of the air electrode under such conditions. Consequently, their subsequent research efforts will focus on developing optimized air electrode materials specifically tailored for metal-supported reversible protonic ceramic cells.
Other contributors include Chenzhao Liu, Bo Liu, Zhenfei Li, Cheng Li, Dong Yan, Jian Li from the School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan.
This research was financially supported by the National Key R&D Program of China (2024YFF0506300), the National Natural Science Foundation of China (52472202, 52302255), and Hubei Province Science and Technology Program (2024EHA045, 2024BCB073). The SEM and XRD characterizations were assisted by the Analytical and Testing Center of Huazhong University of Science and Technology.
About Author
Jia Lichao, Professor of School of Materials Science and Engineering, Huazhong University of Science and Technology, and member of the Fuel Cell Professional Committee of the Chinese Energy Research Society.
He has long been engaged in research on solid oxide fuel cell/electrolysis cell (SOFC/SOEC) electrode materials, single-cell optimization, and stack development. He has presided over more than 20 national and provincial-level projects, including the National Natural Science Foundation of China, the National Key R&D Program International Cooperation Project, the Hubei Provincial Key R&D Program, the Hubei Provincial Outstanding Youth Fund, and the Ministry of Science and Technology Exchange Program. He has published over 120 academic papers and obtained 19 authorized invention patents. He was awarded the Hubei Provincial Young Top-notch Talent Program and serves as an editorial board member or youth editorial board member for journals such as Journal of Advanced Ceramics, SusMat, Chinese Chemical Letters, and Advanced Technical Ceramics.
About Journal of Advanced Ceramics
Journal of Advanced Ceramics (JAC) is an international academic journal that presents the state-of-the-art results of theoretical and experimental studies on the processing, structure, and properties of advanced ceramics and ceramic-based composites. JAC is Fully Open Access, monthly published by Tsinghua University Press, and exclusively available via SciOpen . JAC's 2023 IF is 18.6, ranking in Top 1 (1/31, Q1) among all journals in "Materials Science, Ceramics" category, and its 2024 CiteScore is 25.9 (5/130) in Scopus database. ResearchGate homepage: https://www.researchgate.net/journal/Journal-of-Advanced-Ceramics-2227-8508
