INFLUENCE OF THE METHOD OF FORMING A Pr2CuO4-BASED CATHODE ON THE ELECTROCHEMICAL CHARACTERISTICS OF A PLANAR ELECTROLYTE-SUPPORTED SOFC

Abstract

The influence of the method of organising the cathode microstructure based on Pr2CuO4 (PCO) on the electrochemical characteristics of a model electrolyte-supported solid oxide fuel cell (SOFC) has been investigated. It is shown that an increase in the thickness of the PCO cathode layer and the introduction of a pore-forming agent contribute to an increase in the power density of the SOFC test cell compared to a sample with an initial unmodified cathode structure, whose power density at 850°C was 34 mW/cm2. It was found that the optimum thickness of the cathode layer to achieve maximum electrochemical performance was in the range of 40-50 μm, while the power density achieved was 116 mW/cm2 at 850°C. At the same time, the transition from a single-phase PCO cathode to a composite of PCO-Ce0.9Gd0.1O1.95 (60/40 wt. %) provides an increase in power density up to 130 mW/cm2 at 850°C, while the dynamics of its decrease with reducing temperature is slower compared to the single-phase cathode. The analysis of the changes in the values of the total electrode polarisation resistance of the model SOFC, determined by impedance spectroscopy, as a function of the method of cathode formation, showed that during the transition from the initial sample to the samples with increased thickness of the cathode layer and the composite cathode, a twofold (in the first case) and threefold (in the second case) decrease in the level of polarisation losses is observed, which correlates with an increase in the power density. The proposed methods of modifying the initial cathode microstructure based on PCO show a positive dynamic of increasing the electrochemical activity of the cathode/electrolyte interface and the power density characteristics of the fuel cell as a whole.