The sintering temperature effect on electrochemical properties of Ce0.8Sm0.05Ca0.15O2-δ (SCDC)-La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) heterostructure pellet

Recently, semiconductor-ionic materials (SIMs) have emerged as new functional materials, which possessed high ionic conductivity with successful applications as the electrolyte in advanced low-temperature solid oxide fuel cells (LT-SOFCs). In order to reveal the ion-conducting mechanism in SIM, a typical SIM pellet consisted of semiconductor La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF) and ionic conductor Sm and Ca Co-doped ceria Ce_0.8Sm_0.05Ca_0.15O_2-δ (SCDC) are suffered from sintering at different temperatures. It has been found that the performance of LSCF-SCDC electrolyte fuel cell decreases with the sintering temperature, the cell assembled from LSCF-SCDC pellet sintered at 600 °C exhibits a peak power density (P_max) of 543 mW/cm² at 550 °C and also excellent performance of 312 mW/cm² even at LT (500 °C). On the contrary, devices based on 1000 °C pellet presented a poor P_max of 106 mW/cm². The performance difference may result from the diverse ionic conductivity of SIM pellet through different temperatures sintering. The high-temperature sintering could severely destroy the interface between SCDC and LSCF, which provide fast transport pathways for oxygen ions conduction. Such phenomenon provides direct and strong evidence for the interfacial conduction in LSCF-SCDC SIMs.