The influence of porosity on mechanical strength and electrical conductivity of NiO-3,5YSZ composite and its Ni-3,5YSZ cermet for SOFC anode application
| Reference | Presenter | Authors (Institution) | Abstract |
|---|---|---|---|
| 06-160 | Ihor Polishko | Polishko, I.(Frantsevich Institute for Problems of Materials Science of NASU); Brodnikovskyi, Y.(Frantsevich Institute for Problems of Materials Science of NASU); Brodnikovskyi, D.(Frantsevich Institute for Problems of Materials Science of NASU); Vasyliv, B.(Karpenko Physico-Mechanical Institute of NASU); Podhurska, V.(Karpenko Physico-Mechanical Institute of NASU); Vasylyev, O.(Frantsevich Institute for Problems of Materials Science of NASU); | Solid oxide fuel cell (SOFC) is an electrochemical device that converts the energy of a chemical reaction directly into electrical energy with high efficiency and low environmental impact. The anode-supported cell configuration is the most common SOFC design since lower ohmic resistance could be obtained by decreasing the electrolyte thickness. Because of that anode should provide mechanical stability of whole cell. In addition to high mechanical strength anode should have enough porosity (>30%) to facilitate the fuel supply and remove by-products from reaction site. Obviously high mechanical strength and high porosity are contradictory requirements for anode material and need to find a compromise. Today the typical anode is porous Ni – 8YSZ (zirconia stabilized 8-mol. % yttria) composite since it has high stability in reducing atmosphere, high catalytic activity towards fuel oxidation, and relatively low cost. However, in traditional anode material it is difficult to combine high mechanical strength (~100 MPa) with porosity ~30%. It is known, that partially-stabilized zirconia 3,5YSZ (zirconia stabilized 3,5-mol. % yttria) demonstrated higher mechanical strength that 8YSZ. Replacement traditional ceramic component 8YSZ with much stronger 3,5YSZ should allow increase the porosity with preserving enough mechanical strength. Improved fuel supplying to reaction zone should facilitate passage of electrochemical reaction and, in turn, positively affect the performance of SOFC. In present work the porosity changes of Ni – 3,5YSZ composite during its fabrication and influence of porosity on mechanical strength and electrical conductivity were studied. The porosity was provided by adding starch in NiO and 3,5YSZ powders mixture. Addition of 18-vol. % of pore-former provides in Ni – 3,5YSZ cermet open porosity 47,1 %, and its mechanical strength and electrical conductivity are 74,3 MPa and 0,93*10^6 S/m, respectively.
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