Study Of Anode System For Planar ITSOFC

Solid oxide fuel cell (SOFC) has the advantage of all solid component and high conversion efficiency, which is as high as 80%, so it is one of the focus study in the world. Normally the anode electrode and electrolyte were co-sintered together. To prevent the mixture of oxygen and hydrogen at high temperature, seals, which were pasted on anode electrode, were required.Line structure of starch and ball structure of polymethyl methacrylate( PMMA) as pore-formers for SOFC anode supported layer were compared. The results demonstrated that the the porosity was 29.8%, electronic conductivity was 2000.35S·cm^-1 for 15mass% starch as pore-formers. But the porosity was 36.4% and 59.4%, and conductivity was 1200.0 S·cm^-1 and 1008.45 S·cm^-1 respectively for 15mass% and 30mass% PMMA pore-formers.Discharging curvess for the cell prepared by different pore-formers and their contents demonstrated that when the porosity is lower than 59.4%, the Discharging property increased with the porosity, but the influence of H2 flow rate on Discharging curve is not obvious when the porosity is 59.4%. Three average particle sizes higher than 1μm of NiO were studied as anode functional layer. The cell performance is the highest for the cell prepared NiO-,with the maxium powder density 121 mW·cm^-2 ,but only 81 mW·cm^-2 for NiO-.Scanning electron microscope (SEM) images showed that the particle size of NiO-Ⅰwas about 2μm, but 4.47μm for NiO-Ⅲ.To reduce the NiO particle size, nano NiO-Ⅳproduced by co-precipitation and commercial NiO-Ⅴwere used as SOFC anode functional layer. The maximum power density of the cell was 205.3mW·cm^-2 and 308.2mW·cm^-2 respectively, and the cell power density prepared from NiO-Ⅴcalcined at 700℃increased to 369.0mW·cm^-2 .YSZ coarsened at 1200℃and milled for 12h let the cell power density increase to 390.5mW·cm^-2.Dimension of JC 8YSZ and TOSOH 8YSZ ,which were widely used as SOFC electrolye, were measured. The results showed that they shrinked at 1000℃. The total shrinkage of JC YSZ was 25.2%, but that of TOSOH 8YSZ was 19.0%. Particle analysis showed that the average particle size of TOSOH 8YSZ was 0.71μm, only about 2.5fold of that JC 8YSZ, which was 1.91μm. The electrochemical analynis demonstrated that the electronic donductivity of JC 8YSZ and TOSOH 8YSZ at 800℃were 0.0179S·cm^-1 and 0.0212 S·cm^-1 respectively. The calculated activation energies were 108.35kJ·mol^-1 and 105.67kJ·mol^-1 respectively. The maximum powder density of the cells made up of these two 8YSZ at 800℃were 184.08 mW·cm^-2 for JC 8YSZ and 267.75 mW·cm^-2 for TOSOH 8YSZ. SEM images showed that none of the electrolyte made of this two YSZ was dense, but was denser made of 80%JC YSZ and 20%TOSOH YSZ mixture. When the thickness of the electrolyte was 20μm, the open current voltage of the electrolyte was 1002mV and its power density reached 447mW·cm^-2 while kept stable. However, when the thickness reduced to 13μm, there was only 253mW·cm^-2 for the power density, and 923mV for the OCV, and decreased in 20min. The reason was that the voltage change during anode reduction led to YSZ electrolyte crack.SLABS3 ceramic glass"glue"SOFC other components well. During co-calcined for 100h, Zr element diffused 10μm to glass, Mn with 60μm , Cr and Fe element about 20μm, but none element of the glass would diffuse to SOFC other components, which meet the requirement of compatibility.The OCV test remained higher than 1.05V,demonstrating that seals meet the requirement in 6 circles.However, as the solid seals cause the problem of stack unable replacement, so compressive seals were also studied. Leakage test for alumina silica infiltrated ceramic fiber paper and mica were studied. The results demonstrated that the leakage of the infiltrated ceramic fiber paper was 0.04sccm·cm^-1, which was lower than that of mica. This value is lower than the leakage reported. The infiltrated ceramic fiber paper were stabe in 20 thermal cycles and the weight loss at 800℃under hydrogen atmosphere was 1.7×10^-2g·cm^-2·h^-1 for 200h, which showed no effect on sealing performance.