Novel high ionic conductivity electrolyte membrane based on semiconductor La_0.65Sr_0.3Ce_0.05Cr_0.5Fe_0.5O_3-Δ for low-temperature solid oxide fuel cells

The p-type semiconductor La_0.65Sr_0.3Ce_0.05Cr_0.5Fe_0.5O_3-δ (CLSCrF) is for the first time composited with the ionic conductor Ce_0.8Sm_0.2O_2-δ (SDC) to prepare high ionic conductivity electrolyte membranes for low-temperature solid oxide fuel cells (LT-SOFCs). Experimental results illuminate that the introduction of moderate semiconductor into ionic membrane can improve membrane's ionic conductivity, reduce cell's polarization resistance and accelerate the electrode reaction in cathode zone. With 30 wt% CLSCrF incorporated into the SDC membrane, the cell delivers a maximum power density of 837 mW cm⁻² at 550 °C with the membrane ionic conductivity as high as 0.15 S cm⁻¹. This conductivity value is nearly 2 times higher than that of the simplex ionic membrane SDC. The rectification characteristic test indicates that there is a physical junction effect in the CLSCrF-SDC cells, which can prevent electrons from passing through internally and avoid the short circuit problem effectively. Moreover, the short-term durability test reveals that the developed CLSCrF-SDC cell is capable of stably operating for 18 h at 550 °C under a fixed current density of 234 mA cm⁻². This study suggests that the CLSCrF-SDC is a promising membrane to advance the LT-SOFCs development.