Degradation mechanisms and mitigation strategies of direct methane solid oxide fuel cells

The gradual degradation of the electrical properties of solid oxide fuel cells (SOFC) when operating on C-containing fuels poses a significant obstacle to their widespread implementation in industry. This paper investigates the distribution of carbon deposition and its structural evolution in the traditional SOFC electrode (Ni/YSZ). The carbon deposition weight in direct methane SOFC increases linearly with exposure times without electrochemical reactions. The carbon initially deposits at the triple-phase boundary (TPB) of the anode, subsequently covering the surface of Ni particles and eventually accumulating to form a carbon deposit layer. Three methods for alleviating carbon deposition are compared. The polarization current could inhibit the carbon deposition but the high stress within the cell had resulted in the brittleness of the electrode, as well as significant coking in the central region of the anode after 26 h. Alternating changes in methane and hydrogen can significantly reduce the degradation rate of the cell. The reasonable gas switching frequency is from 60 min to 120 min. After high electrolytic current, the gap between the anode and the electrolyte can be achieved at 68.2 mu m.