Effect of Thickness of Porous Fe24Cr Metal Support on SOFC Performance
The metal-supportedsolid oxide fuel cell(MS-SOFC)is expected to be used in unmanned aerial vehicles,portable power and mobile powers due to its advantages such as low cost,good mechanical properties and fast start-stop capability.In order to improve the performance and lifetime of MS-SOFC,the metal support not only needs to match the thermal expansion coefficient of electrolyte to reduce stress,but also needs high permeability to improve the diffusion and reaction rate of fuel gas.In this work,three kinds of Fe24Cr supports with different thickness of 1 mm,0.8 mm and 0.5 mm were prepared,and their coefficient of thermal expansion were compared with the traditional 430 support.Mean-while,the effects of the thickness on the air permeability and electrochemical performance of the support were investigated.The results showed that the coefficient of thermal expansion of Fe24Cr support is 12.74×10-6 K-1,which is more suitable for zirconia-based electrolyte than the tradi-tional 430 support.Comparing with the 1 mm thick support,the 0.5 mm thick Fe24Cr support can significantly shorten the gas transmission path,increase the gas permeability by about 5 times and increase the output performance by more than 15％.At 800 ℃ the polarization impedance and ohmic impedance of the cell decrease to 0.203 Ω·cm2 and 0.118 Ω·cm2 respectively,and the peak power density reaches 1.215 W/cm2.The distribution of relaxation times(DRT)analysis showed that the reduction of the support thickness contributes greatly to the ohmic impedance of SOFC and the rate of H2 diffusion to the three-phase reaction interface,which can be matched well with the electrochemical performance results of the cell.
metal-supported SOFCthickness of the substratescoefficient of thermal expansiongas permeabilityelectrochemical perfor-mance
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