Simulation-based microstructural optimization of solid oxide fuel cell for low temperature operation

• Lowering solid oxide fuel cells operation temperature via computationally tailoring electrode microstructures.
• Development of a complete cell level multi-scale polarization model for optimizing both SOFCs electrodes.
• Application of nonlinearly functional graded electrodes optimization.

Despite immense potential, the widespread application of solid oxide fuel cells (SOFCs) is hindered by high operating temperatures. Successfully tailoring the microstructures of SOFC electrodes can offset adverse effects of lowering operating temperatures. Our previous work considered functionally graded anode, however, further investigation needs to be done on the cell level optimization of SOFCs considering both anode and cathode to lower cell operating temperature. In this paper, a complete cell level multi-scale polarization model has been developed assuming the electrode particles to be randomly packed spheres. Micro- and macro-models are developed separately and then integrated to establish a cell level model. Suzuki's model is adopted for micro-modeling with ionic-electronic particle size ratio limited from 0.1547 to 6.646. The results of this modeling work closely match the referenced literature. Simulation results show that the performance of SOFCs can be improved with tailored microstructures. The power output of SOFC with nonlinearly graded electrodes shows 28% improvement compared to SOFC with linearly graded electrodes. Moreover, the combination of nonlinear particle-size- and porosity-graded electrodes enable SOFCs to operate at a reduced temperature (as low as 873 K) while maintaining the performance at high temperature of 1273 K.

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