## 3 Results and Discussion
### Microstructure Characterization and Single Cell Performance
Therefore, the SOFC single-cell performance can be improved by optimizing the physical properties and microstructure of the cell components. Developing high performance materials and adopting cost-effective fabrication techniques to produce thin films can improve the performance of low temperature solid oxide fuel cells (LT-SOFC) [39]. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Electrolyte** & **Cathode** & **Anode** & **Fuel** & **Current** & **Operating** & **Power Density** & **Reference** \\  & & & **(Anode/Cathode)** & **Collecting Layer** & **Temperature** (°C) & **(AnW/cm?)** & **Reference** \\ \hline SDC-30 wt\% & LSC-30 wt\% & NNO-40 wt\% & \multirow{2}{*}{H\({}_{2}\)/air} & \multirow{2}{*}{-} & \multirow{2}{*}{680} & \multirow{2}{*}{75.4} & \multirow{2}{*}{This study} \\ Li1.34N=00.66 CO\({}_{3}\) & SDC-Li1.34N=00.66 CO\({}_{3}\) & SDC-Li1.34N=00.66 CO\({}_{3}\) & & & & \\ \hline SDC-20 wt\% & lithitated & \multirow{2}{*}{NO-SDC-(\(\text{LNNa}_{2}\))CO\({}_{3}\)} & \multirow{2}{*}{H\({}_{2}\)/O\({}_{2}\)} & \multirow{2}{*}{-} & \multirow{2}{*}{575} & \multirow{2}{*}{600} & [8] \\ (LiNa)CO\({}_{3}\) & NO-SDC-(\(\text{LNNa}_{2}\))CO\({}_{3}\) & & & & & \\ \hline SDC-20 wt\% & LSC-30 wt\% & \multirow{2}{*}{NNO-SDC-(\(\text{LNNa}_{2}\))CO\({}_{3}\)} & \multirow{2}{*}{H\({}_{2}\)/O\({}_{2}\)} & \multirow{2}{*}{Silver} & \multirow{2}{*}{550} & \multirow{2}{*}{120.4} & [28] \\ (LiNa)CO\({}_{3}\) & SDC-(\(\text{LNNa}_{2}\))CO\({}_{3}\) & SDC-(\(\text{LNNa}_{2}\))CO\({}_{3}\) & & & & \\ \hline SDC-35 wt\% & LSC-45 wt\% & NNO-45 wt\% & \multirow{2}{*}{H\({}_{2}\)/O\({}_{2}\) + CO\({}_{2}\)} & \multirow{2}{*}{-} & \multirow{2}{*}{550} & \multirow{2}{*}{801} & [40] \\ (LiNa)CO\({}_{3}\) & SDC-(\(\text{LNNa}_{2}\))CO\({}_{3}\) & SDC-(\(\text{LNNa}_{2}\))CO\({}_{3}\) & & & & \\ \hline SDC-68 wt\% & lithitated & \multirow{2}{*}{NNO-60 wt\%} & \multirow{2}{*}{H\({}_{2}\)/air} & \multirow{2}{*}{Silver} & \multirow{2}{*}{550} & \multirow{2}{*}{342} & [41] \\ Na\({}_{2}\)CO\({}_{3}\) & SDC-(\(\text{Na}_{2}\))CO\({}_{3}\) & SDC-Na\({}_{2}\)CO\({}_{3}\) & & & & \\ \hline SDC-(\(\text{LNNa}_{2}\))CO\({}_{3}\) & LINCuZnO & LINCuZnO-SDCC & \multicolumn{2}{c}{H\({}_{2}\)/air} & \multirow{2}{*}{-} & \multirow{2}{*}{600} & \multirow{2}{*}{617} & [26] \\ \hline SDC-(\(\text{LNNa}_{2}\))CO\({}_{3}\) & LINCuZnO-SDCC & LINCuZnO-SDCC & \multicolumn{2}{c}{H\({}_{2}\)/O\({}_{2}\)} & \multirow{2}{*}{Silver} & \multirow{2}{*}{580} & \multirow{2}{*}{520} & [42] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Comparison of single-cell performance based on doped cera–carbonate composite electrolyte materials. Under fuel cell conditions, multi-conduction paths or mobility of various ions from the constituent phases (such as Li\({}^{+}\), Na\({}^{+}\), K\({}^{+}\), H\({}^{+}\), CO\({}_{3}\)\({}^{2-}\), and O\({}^{2-}\)) co-exist inside the composite electrolyte materials [43]. This mixed-ionic property of carbonate-based electrolyte materials leads to superionic conduction behavior, thus exhibiting superior ionic conductivity at low operating temperatures. Moreover, the presence of the molten carbonate phase in the electrode microstructure could minimize the electrolyte-electrode interface polarization resistance, by enlarging the triple-phase boundary [44]. This condition contributes toward the fast ion transport of O\({}^{2-}\) and H\({}^{+}\) ions at the electrolyte-electrode interface, consequently increasing the overall cell performance [45]. The presence of a molten carbonate enhances the oxygen adsorption (Equations (1)-(3)) and promotes the oxygen reduction reaction process (Equation (4)) with the formation of intermediate products (CO\({}_{4}^{2-}\) and CO\({}_{5}^{2-}\)) from CO\({}_{3}^{2-}\) and O\({}_{2}\)[46].