Mixed ionic-electronic conductor membrane based fuel cells by incorporating semiconductor Ni_0.8Co_0.15Al_0.05LiO_2−Δ into the Ce_0.8Sm_0.2O_2−Δ-Na₂CO₃ electrolyte

In the present study, a novel composite was fabricated by incorporating the semiconductor Ni_0.8Co_0.15Al_0.05LiO_2−δ(NCAL) into the ionic electrolyte Ce_0.8Sm_0.2O_2−δ-Na₂CO₃(NSDC), and further developed as a mixed-conducting membrane for single layer fuel cell (SLFC) applications. Experimentally, the crystal structure, morphology, chemical composition and thermo-stability of the composite were characterized by XRD, SEM and TGA. The best cell performance was investigated when the NSDC-NCAL membrane was optimized at a weight ratio of 6:4. On this basis, a number of interesting findings were obtained: i) the mixed conducting membrane did not cause any short circuit; on the contrary, the cell reached a decent open circuit voltage (OCV) of ∼1.0 V. ii) a high power density of 1072 mW cm⁻²was achieved at 550 °C for the NSDC-NCAL membrane based cell, which was much better than that using a pure NSDC electrolyte membrane. Electrochemical impedance spectroscopy (EIS) showed that the NSDC-NCAL composite exhibited significantly improved grain boundary conduction and reduced electrode polarizations, contributing to the resultant performance. To consolidate the usefulness of the device, we also conducted the durability test. The above findings indicate the strategy of introducing mixed NSDC-NCAL membrane is feasible for high-performance SLFCs operating at low temperatures.