Proton conductivity and chemical stability of Li_2SO_4 based electrolyte in a H_2S-air fuel cell

摘要

Proton conductivity of Li_2SO_4-Al_2O_3 (LA) based electrolyte was determined under non-reducing dynamic conditions using current interruption technique. The performance of LA as electrolyte has been examined at 600 deg C in a H_2S fuel cell with MoS_2-NiS as anode catalyst and NiO as cathode catalyst. XRD and XPS results show that Li_2SO_4 is not stable when heated in pure H_2S as it is reduced to Li_2S by hydrogen produced in equilibrium amounts from the thermal decomposition of H2S. In contrast, under dynamic operation in a H_2S fuel cell the concentration of H_2 is much lower, the reduction reaction does not occur and, surprisingly, Li_2SO_4 is a chemically stable electrolyte.