Design and optimization of self-assembled nanocomposite electrodes for SOFCs

Nanocomposites exhibit improved electrochemical and mechanical properties compared to single-phase materials, making them promising for the development of efficient and durable electrodes in solid oxide fuel cells (SOFCs). However, conventional fabrication methods usually involve multiple steps and high sintering temperatures, potentially leading to adverse effects on the properties of these materials due to excessive grain growth or reactivity among the cell components. In this study, nanocomposite electrodes of Sm_0.5Sr_0.5CoO_3-δ - Ce_0.9Sm_0.1O_1.95 (SSC–CSO) are prepared using a co-synthesis freeze-drying method, followed by screen-printing deposition and sintering at high temperatures. Alternatively, they are prepared through direct spray-pyrolysis deposition on the electrolyte at reduced temperatures. In both cases, the intimate mixture of SSC and CSO phases not only partially suppresses grain growth but also provides extended actives sites for the electrochemical reactions. More interestingly, when the electrodes are directly assembled onto the electrolyte via spray-pyrolysis, no adverse chemical interaction between the SSC and CSO components is observed, unlike the screen-printed electrodes. These nanocomposite electrodes exhibit remarkably high thermal stability during annealing cycles at intermediate temperature. Polarization resistance values as low as 0.09 Ω cm² are achieved at 600 °C, further decreasing to 0.04 and 0.015 Ω cm² under cathodic and anodic polarization, respectively.