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The key technical challenges that fuel cell developers need to address are performance, durability, and cost. All three need to be achieved in parallel; however, there are often competitive tensions, e.g., performance is achieved at the expense of durability. Stability and resistance to degradation under prolonged operation are key parameters. There is considerable interest in developing new cathodes that are better able to function at lower temperature to facilitate low cost manufacture. For anodes, the ability of the solid oxide fuel cell (SOFC) to better utilize commonly available fuels at high efficiency, avoid coking and sulfur poisoning or resistance to oxidation at high utilization are all key. Optimizing a new electrode material requires considerable process development. The use of solution techniques to impregnate an already optimized electrode skeleton, offers a fast and efficient way to evaluate new electrode materials. It can also offer low cost routes to manufacture novel structures and to fine tune already known structures. Here impregnation methodologies are discussed, spectral and surface characterization are considered, and the recent efforts to optimize both cathode and anode functionalities are reviewed. Finally recent exemplifications are reviewed and future challenges and opportunities for the impregnation approach in SOFCs are explored.

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Excellent area-specific-resistance (ASR) values have been exhibited by cathode materials with a Sr-doped layer perovskite type structure and therefore show themselves to be possible candidates for intermediate-temperature-operating solid oxide fuel cell (IT-SOFC, 600–800°C) applications. SmnormalBa0.5normalSr0.5normalCo2normalO5+δ (SBSCO) electrode was sintered onto 10mol% gadolinia-doped ceria ( normalCe0.9normalGd0.1normalO2 , CGO91) at 1000°C to form symmetrical cells and exhibited an ASR value of 0.092Ωcm2 at 700°C . The lowest ASR value was observed when the composite cathode of 50wt% of SBSCO and 50wt% of CGO91 (SBSCO50) was used in conjunction with an interlayer of CGO91 applied between the electrode and 8mol% normalY2normalO3 stabilized ZrnormalO2 electrolyte. These were 0.12Ωcm2 at 600°C and 0.019Ωcm2 at 700°C , respectively. The coefficient of thermal expansion (CTE) of SBSCO was 21.9×10−6normalK−1 at 700°C . However, the CTE of the composite cathode of SBSCO50 was shown to be 13.6×10−6normalK−1 at 700°C , this being more compatable with the other components within the cell.

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