Performance of Ce0.85Sm0.15O1.9-La0.9Sr0.1Ga0.8Mg0.2O2.85 composite electrolytes for intermediate-temperature solid oxide fuel cells

► We fabricated the composite electrolytes with SDC and LSGM. ► The grain boundary resistance significantly decreased. ► The influence of electronic conduction from the SDC phase is reduced. ► This composite electrolyte is a promising electrolyte material for IT-SOFCs.