Preparation and characterization of silver-modified La0.8Sr0.2MnO3 cathode powders for solid oxide fuel cells by chemical reduction method

Abstract

Herein a chemical reduction method is proposed in order to modify the solid oxide fuel cells (SOFC) traditional cathode material La0.8Sr0.2MnO3−x (LSM). Silver nanoparticles were prepared by the reduction of ammoniacal silver nitrate with ascorbic acid in dilute aqueous solutions containing PVP. The obtained LSM–Ag composite powders were characterized by XRD, SEM, EDX, and STEM. The results showed that the LSM–Ag composite powder possess an elaborated fine structure with a homogeneous distribution of Ag and LSM, which effectively shortens the diffusion pathway for electrons and adsorbed oxygen. The electrochemical performance of the LSM–Ag cathode with different Ag loadings was investigated. A cathode loading with 1 wt.% Ag exhibited an area specific resistance as low as 0.45 Ω cm2 at 750 °C, compared to around 1.1 Ω cm2 for a pure LSM electrode. Similarly an anode-supported SOFC with 1 wt.% Ag in the cathode shows a peak power density of 1199 mW cm−1, higher than the value of 717 mW cm−1 achieved for a similar cell with a LSM cathode. Increasing the Ag loading is shown to have an insignificant effect on improving electrocatalytic performance at 750 °C, however it can increase output power at 650 °C.