Protonic ceramic fuel cells (PCFCs) can efficiently convert the chemical energy of fuel into electricity, with alternative fuel range. Ammonia has been regarded as a promising fuel for PCFCs due to its carbon-free and hydrogen-rich properties and easy storage/transportation. However, the performance of ammonia PCFCs (NH3-PCFCs) is inferior to the hydrogen PCFCs (H2-PCFCs) because of sluggish and complex kinetics at anode. In this work, we establish an elementary reaction kinetic model for NH3-PCFCs, investigate the effect of reaction parameters, and explore the coupling mechanism between the ammonia decomposition and electrochemical reaction. Importantly, the ammonia decomposition and electrochemical reaction can be regulated by adjusting anode parameters, then affecting the performance ratio of NH3-PCFCs and H2-PCFCs. Thus, the ammonia-hydrogen performance ratio of the cell can exceed 95% at 550 ℃ after accelerating the ammonia decomposition reaction. Our work provides insights into the kinetics in NH3-PCFCs for improving their performance with optimization.

In this study, we prepared SrR2O4+δ (SRO, R=Y, Yb, Gd, Sm) of brownmillerite structure. Among the four n-type SRO semiconductors, SYO is the most negative in conduction band and the smallest in band gap. As a result, the SYO-based SOFC can offer a maximum power density (MPD) of 1.03W/cm-2 at 800°C, which is higher than that based on the other three SRO oxides. The introduction of larger Sr2+ at the B sites of Sr1+xY2-xO4+δ [SYO(x)] causes decrease of band gap, resulting in a 4-fold increase of electronic conductivity. The foreign Sr2+ creates surface oxygen vacancies to boost interfacial transport. The measurement of oxygen transport reveals that SYO(0.10) exhibits a bulk diffusion coefficient 500 folds higher than that of LSM. An anode supported Ni-YSZ|YSZ|SYO(0.10)-60YSZ DA-SOFC yields an MPD of 0.24W/cm2 at 600°C and 1.21 W/cm2 at 800°C with remarkable stability, about 1.73- and 1.29-folds higher than that of LSM-based SOFC, respectively.