An electrochemical model of proton-conducting solid oxide fuel cells(H-SOFCs) is built for investigating the electrochemical performance, Faraday efficiency and energy efficiency of co-generation of electric energy and ethylene in H-SOFCs. The simulation results show that ethylene production based on H-SOFCs needs external energy. Increasing the temperature is beneficial for improving the conversion rate of ethane and reducing the polarization loss of fuel cells. For the simulated H-SOFCs, the ohmic and activation over potentials are dominant, and the concentration over potential is almost negligible. The non-negligible electronic conductivity in the proton-conducting electrolyte layer leads to the internal short circuit of the fuel cells and the formation of leakage current. The leakage current density increases with the output voltage, resulting in the decrease of Faraday efficiency and energy efficiency.

Direct carbon solid oxide fuel cells (DC-SOFCs) are highly efficient power generation devices that can directly convert the chemical energy of solid carbon fuel into electrical energy. Modeling research has important guiding significance for the development of DC-SOFCs technology. However, current models of DC-SOFCs are steady-state simulation, which makes it difficult to analyze the evolution of DC-SOFCs performance over time. To address this problem, the consumption of solid carbon fuel is simulated by using the shrinking core model. The dynamic simulation of DC-SOFCs is carried out by combining the shrinking core model and the multiphysics coupling model to simulate the dynamic changes during the operation of cells. The impact of carbon fuel consumption on cells’ performance and stability is evaluated. The results show that the size of carbon particles gradually decreases over time, causing the change of CO concentration in the anode chamber, which in turn affects the performance of DC-SOFCs. Smaller carbon particles help improve the performance of cells, but their consumption rate is faster. The initial performance of cells with larger carbon particles is relatively low, but a relatively stable output performance of cells can be maintained.

The mixed oxygen ionic-electronic conducting oxides have been widely used in the fields of solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs). The accurate measurement of ionic transport numbers in the mixed oxygen ionic-electronic conducting oxides is significant for their performance optimization and application. Electromotive force (EMF) method is one of the most widely used approaches to measure the ionic transport numbers. However, the measured result of EMF method is the apparent ionic transport number (t_i^app). CeO₂-based electrolyte was selected as an object, while a model of defect distribution was established. With this model, the distribution of ionic transport numbers across the CeO₂-based electrolyte membrane was analyzed and the effect of test conditions on t_i^app was examined by using the EMF method, thus evaluating the accuracy of the EMF method. It is demonstrated that the ionic transport number is inhomogeneous across the electrolyte membrane. t_i^app is significantly dependent on thickness of the electrolyte membrane when the electrolyte membrane is relatively thin. When there is a large gradient of oxygen chemical potential on both sides of the electrolyte membrane (P_O2^high/P_O2^low>10²⁵), t_i^app tends to be ionic transport number of the electrolyte layer at high P_O2 side and decreases with increasing temperature and the electronic conductivity coefficient of the electrolyte. t_i^app tends to be ionic transport number of the electrolyte layer at the low P_O2 side when the two sides of the electrolyte layer are in reducing atmospheres(P_O2<10^‒20 atm). t_i^app mainly reflects the ionic transport number of the electrolyte layer at the high P_O2 side, when P_O2 on the two sides of the electrolyte layer are large (P_O2>10^‒15 atm).