Fabrication Of Anode/Electrolyte Bi-Layer For Solid Oxide Fuel Cells By Single Step

In order to improve the power density of solid oxide fuel cells (SOFC), we must decrease the impedance of single cell. Fabricating a thin electrolyte film on porous anode is a feasible way. A thinner electrolyte can decrease the Ohmic resistance enormously. In the past, the anode and electrolyte were manufactured separately. Making use of the different subside ratios between different materials, I tried to make them by single step.Because NiO and YSZ had different shrinkages at high temperature, researchers often pre-heated NiO. For further research, I tested many characters of NiO after heated 2 hours from 200-1100℃. From the results of the granularity distributing, we know 700℃is the lowest temperature to enhance the size of a NiO group. But after NiO was milled for 20 minutes, the result revealed that even be pre-heated at 200℃, the link force between NiO can be decreased. According to the different shrinkages of NiO and YSZ, we could estimate the optimum temperature to deal with NiO.During the process of making planar anode support by slip casting, I found a simple way to make anode and electrolyte by one step. The single cell based on this technique reached to a good performance too. The OCV was over 1.12V, and the power density reached to 0.5W/cm2. By analyzing the impedance spectrum, we found the polarization limited the performance of this cell.After milled with graphite for 24 hours, the slurry was sprayed onto the mould. Because the powder moved very fast, the materials fallen on the mould was uniform. After pre-sintered at 1000℃and made a electrolyte by slip casting, we got a single cell. I-V curves showed that: the performance of single cell decreased when the amount of graphite increased. The maximum power density was 0.14W/cm2 only. The SEM photos showed some planer hole in the anode, and they were isolated from each other.After milled with alcohol and PVB, NiO and YSZ became well-proportioned slurry. Because alcohol could evaporate into the air rapidly, we just need to pour the slurry into a planer mold. If the mold was sealed for a long time, we can get anode/electrolyte structure; if the mold was exposed to the air directly, we will get anode only. Single cell based on the two could supply a power density of 0.34 and 0.42W/cm2 separately. From the impedance spectrum we got the conclusion that the power density can be improved and reached 0.5W/cm2.As I know, the single step casting was a completely new plan. It will push SOFC into real life if this method was optimized.