Effects of Electrode Composition and Thickness on the Mechanical Performance of a Solid Oxide Fuel Cell

Xiurong Fang,Zijing Lin,Jiang Zhu

doi:10.3390/en11071735

Xiurong Fang, Zijing Lin + Show 1 more

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https://doi.org/10.3390/en11071735

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Abstract

Mechanical damage is a major factor limiting the long-term stability of solid oxide fuel cells (SOFCs). Here, the mechanical stability of planar SOFCs consisting of Ni-YSZ anode/YSZ electrolyte/LSM-YSZ cathode (Ni=Nickel, YSZ=yttria-stabilized zirconia, LSM=lanthanum strontium manganite) is analyzed by a structural mechanics model with composition dependent mechanical properties. Influencing factors considered include: the Ni and LSM volume fractions, the thicknesses of anode, cathode and electrolyte layers, and the cell types of anode-, cathode-, and electrolyte-supported designs. It is found that (i) the anode failure probability increases with the Ni content. However, SOFCs remain mechanically safe if the Ni volume fraction is below 65%. (ii) An LSM volume fraction of over 40% is required to maintain the mechanical integrity of cathode. (iii) For an anode-supported cell with a 20 μm thick electrolyte, the anode thickness should be more than 0.5 mm to be mechanically stable. (iv) The anode-supported cell is found to be mechanically safer than that of the electrolyte-supported cell.

Highlights

Solid oxide fuel cell (SOFC) converts the chemical energy of fuel into electricity through an electrochemical process
The stress distribution is dependent on the mechanical properties and on the material compositions and layer thicknesses of pSOFC components
The mechanical properties necessary for the structural mechanics analysis are determined by a theoretical model that links the properties with the compositions of materials

Summary

Introduction

Solid oxide fuel cell (SOFC) converts the chemical energy of fuel into electricity through an electrochemical process. Owing to its high operating temperature, SOFC is fuel flexible, e.g., CO or reformed hydrocarbon may be used as fuel directly. The fuel flexibility is extremely important in practice as fossil fuel will remain dominant in the several decades [1]. The SOFC technology is actively pursued worldwide. The high operating temperature, severely limits the material choices and designs of SOFCs. There have been a large number of studies on the material development based on electrical conductivity, chemical/electrochemical activities, and stabilities. Studies on the mechanical stabilities of SOFC materials are, scarce

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