Solid oxide fuel cells with proton-conducting La0.99Ca0.01NbO4 electrolyte

Improved performance of IT-SOFC by negative thermal expansion Sm0.85Zn0.15MnO3addition in Ba0.5Sr0.5Fe0.8Cu0.1Ti0.1O3-δcathode

To improve performance of intermediate temperature solid oxide fuel cells (IT-SOFCs), the negative thermal expansion (NTE) material Sm_0.85Zn_0.15MnO₃(SZM) is introduced in Ba_0.5Sr_0.5Fe_0.8Cu_0.1Ti_0.1O_3-δ(BSFCT) cathode. XRD results indicate that BSFCT, SZM and Ce_0.8Sm_0.2O_2-δ(SDC) oxides have good chemical compatibility up to 1173 K. The average linear thermal expansion coefficient of BSFCT-xSZM (x= 0, 10, 20 and 30 wt.%) decreases markedly from 29.2 × 10^-6 K^-1forx= 0 wt.% to 15.6 × 10^-6 K^-1forx= 30 wt.%. The electrochemical performance of single cells with configuration of NiO-BZCY|SDC|BSFCT-xSZM is comparatively investigated in the 773-973 K. The best performance is observed forx= 20 wt.%, which should be caused by the balance between thermal matching of cathode/electrolyte layers and oxygen reduction reaction activity of composite cathodes. The corresponding peak power density in the 773-973 K is 136-918 mW cm^-2, which is 249%-64% higher than that (39-559 mW cm^-2) with single BSFCT cathode. Due to the existence of electron blocking layer at anode/electrolyte interface, the open circuit voltage of all cells is higher than 1.0 V. In short, the introduction of NTE oxide in conventional cathode materials may provide an effective strategy to enhance the performance of IT-SOFCs with electron blocking layer.

Solid-Solid Interfaces in Protonic Ceramic Devices: A Critical Review

The literature concerning protonic ceramic devices is critically reviewed focusing the reader's attention on the structure, composition, and phenomena taking place at solid-solid interfaces. These interfaces play a crucial role in the overall device performance, and the relevance of understanding the phenomena taking place at the interfaces for the further improvement of electrochemical protonic ceramic devices is therefore stressed. The grain boundaries and heterostructures in electrolytic membranes, the electrode-electrolyte contacts, and the interfaces within composite anode and cathode materials are all considered, with specific concern to advanced techniques of characterization and to computational modeling by ab initio approaches. An outlook about future developments and improvements highlights the necessity of a deeper insight into the advanced analysis of what happens at the solid-solid interfaces and of in situ/operando investigations that are presently sporadic in the literature on protonic ceramic devices.

Solid Oxide Electrochemical Systems: Material Degradation Processes and Novel Mitigation Approaches

Solid oxide electrochemical systems, such as solid oxide fuel cells (SOFC), solid oxide electrolysis cells (SOEC), and oxygen transport membranes (OTM) enable clean and reliable production of energy or fuel for a range of applications, including, but not limited to, residential, commercial, industrial, and grid-support. These systems utilize solid-state ceramic oxides which offer enhanced stability, fuel flexibility, and high energy conversion efficiency throughout operation. However, the nature of system conditions, such as high temperatures, complex redox atmosphere, and presence of volatile reactive species become taxing on solid oxide materials and limit their viability during long-term operation. Ongoing research efforts to identify the material corrosion and degradation phenomena, as well as discover possible mitigation techniques to extend material efficiency and longevity, is the current focus of the research and industrial community. In this review, degradation processes in select solid oxide electrochemical systems, system components, and comprising materials will be discussed. Overall degradation phenomena are presented and certain degradation mechanisms are discussed. State-of-the-art technologies to mitigate or minimize the above-mentioned degradation processes are presented.