Sodium Doped Strontium Silicates as Electrolyte for Intermediate Temperature Solid Oxide Fuel Cells

摘要

The conventional solid oxide fuel cell electrolyte, yttria stabilized zirconia requires high operating temperature (800-1000°C) to achieve sufficient oxide ion conductivity, which increases the cost and exacerbates the instability between the components. Therefore, there is considerable interest in developing alternative electrolytes (σ > 10~(-2) S/cm) at intermediate temperature (IT, 500-700°C). Hence, here we successfully synthesized IT operable electrolytes Sr_(1-x)Na_xSiO_(3-δ) (x = 0.0, 0.45) by solid state reactions. From the XRD, it is evident that both samples can be indexed to monoclinic c2/c space group (15). NMR reveals a broad peak at ～ -87 ppm for Sr_(0.55)Na_(0.45)SiO_(3-δ) indicating the presence of amorphous Na_2Si_2O_5 phase. FE-SEM and WDS mapping shows the segregation of amorphous Na_2Si_2O_5 along the grain boundaries. Sr_(0.55)Na_(0.45)SiO_(3-δ) exhibits high conductivity in the measured temperature range, which makes it an electrolyte for IT-SOFCs.