In situ formation of a solid oxide fuel cell (SOFC) cermet anode by NiWO_4 reduction

摘要

The presented work describes a process for producing a mixed-conducting SOFC cermet anode through the in situ reduction of a ternary oxide. A porous nickel tungstenate (NiWO_4) was screen-printed and bonded onto an yttrium-stabilized zirconia (YSZ) electrolyte-supported SOFC by treatment at 1000 ℃ for 1 h. An (La,Sr)MnO_3/Ce_(0.9)Gd_(0.1)O_2(LSM/GDC) was utilized as the cathode with the NiWO4 acting as the anode for the SOFC. The ~ 1-cm diameter fuel cell with a ～ 100-nm thick YSZ electrolyte was tested in H_2 fuel at 800 ℃. During the insertion of the H_2 fuel, the NiWO_4 was reduced to form a Ni/WO_x cermet composite that consisted of a fine mixture of Ni-nanoparticles dispersed over the porous WO_x support structure. A maximum power density of ~ 104 mW cm~(-2) was attained for the reduced NiWO_4 anode, even with an un-optimized and dense microstructure, on an electrolyte-supported cell. The power density was increased to ～ 165 Mw cm~(-2) with the incorporation of GDC powder into the NiWO_4 anode. The same NiWO_4/GDC composite was tested within a fuel stream of H_2 containing 10 ppm PH_3. The cell's degradation rate was 0.006 V h~(-1) for 5 h at 750 ℃, which is similar to that observed for conventional Ni/ YSZ cermets.