Effect of graphite content on cell performance and microstructure in solid oxide fuel cells

The presence of graphite materials in the anode composites of high-temperature solid oxide fuel cells exerts a significant effect on the microstructure of the electrodes and electrochemical performance of the cells. Herein, the amount of graphite in the anode materials was intentionally varied during the electrode processing steps. The effect of graphite content on cell performance was evaluated in terms of the resultant microstructure, mechanical strength, and electrochemical performance. A higher quantity of graphite in the anode composite leads to higher porosity, and consequently, to the opposing effects of enhanced electrochemical performance during the initial stages and faster degradation of the current-voltage characteristics. However, among the evaluated graphite-controlled anodes, the one with the lowest graphite content exhibited the slowest degradation rate and a fairly poor electrochemical performance. The balance between the microstructure and the corresponding electrochemical performance is discussed in terms of the optimization of high-performance solid oxide fuel cells.