Preparation and characterization of Sm_(0.2)Ge_(0.8)O_(0.9)/Na_2CO_3 nanocomposite electrolyte for low-temperature solid oxide fuel cells

摘要

Sm_(0.2)Ce_(0.8)O_(1.9) (SDC)/Na_2CO_3 nanocomposite synthesized by the co-precipitation process has been investigated for the potential electrolyte application in low-temperature solid oxide fuel cells (SOFCs). The conduction mechanism of the SDC/Na_2CO_3 nanocomposite has been studied. The performance of 20 mW cm~(-2) at 490 ℃ for fuel cell using Na_2CO_3 as electrolyte has been obtained and the proton conduction mechanism has been proposed. This communication demonstrates the feasibility of direct utilization of methanol in low-temperature SOFCs with the SDC/Na_2CO_3 nanocomposite electrolyte. A fairly high peak power density of 512 mW cm~(-2) at 550 ℃ for fuel cell fueled by methanol has been achieved. Thermodynamical equilibrium composition for the mixture of steam/methanol has been calculated, and no presence of C is predicted over the entire temperature range. The long-term stability test of open circuit voltage (OCV) indicates the SDC/Na_2CO_3 nanocomposite electrolyte can keep stable and no visual carbon deposition has been observed over the anode surface.