A novel Sn0.9Ni0.1P2O7/KPO3 composite electrolyte with improved electrical properties for intermediate temperature fuel cells

Abstract

In this study, a novel Sn0.9Ni0.1P2O7/KPO3 composite electrolyte was prepared by a mechanical mixing method. The Raman spectrum and X-ray diffraction of Sn0.9Ni0.1P2O7/KPO3 indicated that the main microstructure is pyrophosphate phase and KPO3 mainly exists in amorphous state in the composite. The intermediate temperature (400–700 °C) electrical properties of Sn0.9Ni0.1P2O7/KPO3 were studied by means of electrochemical impedance spectroscopy. The maximum conductivity of Sn0.9Ni0.1P2O7/KPO3 was 6.1 × 10−2 S cm−1 in a dry nitrogen atmosphere at 700 °C. The log σ ～ log (pO2) results showed that Sn0.9Ni0.1P2O7/KPO3 is a pure ionic conductor in an oxidizing atmosphere and a hybrid conductor of proton and electron hole under a reductive atmosphere. The maximum power density of Sn0.9Ni0.1P2O7/KPO3 (thickness: 1.2 mm) was 434 mW cm−2 at 700 °C.