Highly active and stable nanocomposite anode for solid oxide fuel cells on non-conductive substrate

Thin film solid oxide fuel cells (TF−SOFCs) with mixed ionic electronic conducting (MIEC) Ni−GDC anode comprise a practical solution to alleviate the poor ionic conductivity and sluggish reaction kinetics of low-temperature SOFCs (< 600 °C). In the present study, we fabricate TF−SOFCs using a magnetron sputtering system. To finely adjust the composition ratio of the nickel cermet anode, we deposit NiO−GDC via a reactive co-sputtering process, which reduces the sputtering yield of nickel. We fabricate NiO−GDC anodes with various composition ratios by changing the sputtering power for the nickel target (50–100 W), while maintaining the sputtering power for the GDC target (50 W). The electrochemical performance of the NiO−GDC anode-based TF−SOFCs is successfully optimized by controlling the composition, crystallinity, and surface morphology of the anodes. Structural analysis reveals that the optimized composition ratio of NiO (64.46 vol% Ni) in cermet is higher than that of conventional sintered nickel-based cermet anode (40–50 vol% Ni), which is attributed to the sensitive characteristics of the nano-sized grain structure to thermal agglomeration in a reducing environment. Consequently, we obtain the most stable structure and the highest performance (439.5 mW/cm² at 500 °C) with the optimal NiO−GDC composition (NiO 75 W / GDC 50 W).