Electrochemical characteristics of electrospun La0.6Sr0.4Co0.2Fe0.8O3−δ-Gd0.1Ce0.9O1.95 cathode

Abstract

The poor activity of cathode materials for electrochemical reduction of oxygen in intermediate and low temperature regime (<700°C) is a key obstacle to reduced-temperature operation of solid oxide fuel cells (SOFCs). In our previous work, the direct methane fuel cell exhibits approximately 1Wcm−2 at 650°C in hydrogen atmosphere without any functional layers when the electrospun LSCF–GDC cathode was applied into the La2Sn2O7–Ni–GDC anode-supported cell, which is approximately two times higher performance than 0.45Wcm−2 of the cell with the conventional LSCF–GDC cathode. For detailed analysis of the fibrous cathode, the symmetrical cells with the electrospun and conventional LSCF–GDC cathode are fabricated, and then their electrochemical characteristics are measured by using electrochemical impedance spectroscopy (EIS). Each resistance contribution is determined by equivalent circuit consisting of a series resistance (Rs) and three arcs to describe the polarization resistance of the cathode. Total polarization resistance of the electrospun LSCF–GDC cathode is approximately two times lower than that of the conventional LSCF–GDC cathode at 650°C, which is attributed to fibrous microstructures and large amount of pores in 100–200nm. The results correspond to the difference in the cell performances obtained from our previous work.