Facile preparation of Cu2+-doped Tin(IV) pyrophosphate /potassium metaphosphate composite as a highly efficient electrolyte for intermediate temperature SOFCs

Abstract

In this study, a Sn0.95Cu0.05P2O7/KPO3 composite ceramic was synthesized via a facile solid state reaction method and characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and Raman spectroscopy. The intermediate temperature electrical properties were evaluated using impedance spectroscopy. The results showed that the microstructure of the Sn0.95Cu0.05P22O7/KPO3 electrolyte pellet plays an important role in determining electrical properties, and amorphous secondary phases appreciably influence proton conduction. The highest conductivity of Sn0.95Cu0.05P22O7/KPO3 was 3.4x10-2 S·cm-1 in a dry nitrogen atmosphere at 700 °C. The operation tests of an H2/O2 fuel cell with the Sn0.95Cu0.05P22O7/KPO3 composite electrolyte showed an open circuit voltage of approximately 1.06 V and a maximum power output density of 218.9 mW·cm-2 at 700 °C. This work offers new alternatives for the design of metal pyrophosphates composite electrolyte.