Solid oxide fuel cell reliability and performance modeling and fabrication by spray pyrolysis

2014

ECS Trans.

Self Cite

Solid oxide fuel cells (SOFCs) are blessed with high efficiency, the capability of using a variety of hydrocarbon fuels, and high impurity tolerance. Functionally graded electrodes have previously been investigated to improve SOFCs performance with controlled microstructure. However, little investigation has been focused on the cell-level optimization of power output for nonlinearly graded electrode microstructures. In this work, a multiscale electrode polarization model of SOFCs has been expanded and developed to a cell-level model. The cell-level SOFCs model has been utilized to disclose the complex relationship among the transport phenomena, which include the transports of electron, ion and gas molecules through the electrode and the electrochemical reaction at the triple phase boundaries. The work advances the understanding of the cell performance with graded microstructures. The performance of functionally graded electrodes has been analyzed to understand the effects of tailored electrode microstructures on cell power output.

Section: Resultsmentioning

confidence: 99%

Section: ( Sin( ))mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Peak Power Optimization of Solid Oxide Fuel Cells with Particle Size and Porosity Grading

2014

ECS Trans.

Self Cite

“…With up to 60% energy efficiency and a life expectancy of 40,000 hours, the SOFC has emerged as an ideal candidate to meet the energy challenges of the modern world. [1][2][3] However, the commercialization of SOFC is hindered due to its high operating temperature, manufacturing cost, and structural instability. [4][5][6] Structural evolution of SOFC often leads to the structural failure and shortening of SOFC lifetime.…”

mentioning

confidence: 99%

Meso-Scale Phase-Field Modeling of Microstructural Evolution in Solid Oxide Fuel Cells

2016

J. Electrochem. Soc.

Self Cite

Microstructural evolution occurs in solid oxide fuel cells (SOFCs) during operation, which cause severe electrochemical performance degradation as well as structural failure such as crack formation. Nickel (Ni) particle coarsening is believed to cause microstructural evolution in the Ni-based anode of SOFCs. Furthermore, the accumulation of expanded pores during the microstructural evolution is responsible for crack formation. Based on the diffuse-interface theory and the phase-field method, integrating both Cahn-Hilliard equation and Ginzburg-Landau equation, a meso-scale phase-field model was established to investigate microstructural evolution and crack formation in the Ni / Yttria Stabilized Zirconia (YSZ) anode of SOFCs. Then, the model was applied to explore the coupling effects of microstructural evolution on SOFCs performance degradation. Simulation results show that particle size, porosity, and particle size ratio of Ni-YSZ are most influential parameters in microstructural evolution. It was found that the triple phase boundaries (TPBs) area was decreased by 24% and power density was decreased by 11.03% after 1000 hours of operation. In addition, the power density was decreased by 27%. This work is expected to provide us a comprehensive understanding of SOFCs' microstructural evolution as well as a tool for SOFC's performance degradation analysis. Solid oxide fuel cells (SOFCs) could be one possible solution to the depleting energy resources of the modern world due to its fuel flexibility, low carbon emissions, and high efficiency. With up to 60% energy efficiency and a life expectancy of 40,000 hours, the SOFC has emerged as an ideal candidate to meet the energy challenges of the modern world.1-3 However, the commercialization of SOFC is hindered due to its high operating temperature, manufacturing cost, and structural instability.4-6 Structural evolution of SOFC often leads to the structural failure and shortening of SOFC lifetime. 7,8 Moreover, structural evolution results in compromising SOFCs' electrochemical performance, mostly in the electrodes.A SOFC consists of both electrodes (i.e., anode and cathode) and a ceramic electrolyte. The anode is consisted of ion conducting phase and electron conducting phase to facilitate the fuel oxidation reaction. 9The cathode reduces the oxygen into oxygen ion, which is then diffused to anode through the ceramic electrolyte, such as yttria stabilized zirconia (YSZ).10 Electrochemical reaction of SOFC mainly occurs in the triple phase boundary (TPB) area, 11 where the pore phase, the ion conducting phase, and electron conducting phase join to convert chemical energy of fuel gases to electrical energy. 1,8,12,13 TPB area is the key microstructural property controlling the electrochemical activities of SOFC.14 It is desired to have a stable microstructure with optimized TPB area. 15,16 However, recent studies reveal that TPB area is often diminished due to microstructure evolution. 10,[17][18][19][20] The microstructure evolution is controlled by the Ni particle c...

Phase Field Simulation Coupling Microstructural Evolution and Crack Propagation during Performance Degradation of Solid Oxide Fuel Cells

2015

ECS Trans.

Microstructural evolution and crack propagation occur in Solid Oxide Fuel Cells (SOFCs) at elevated operation temperatures (above 600°C). These phenomena cause performance degradation in electrochemical activity and compromise of structural integrity of SOFCs as well. Nickel (Ni) coarsening of Ni-yttria stabilized zirconia (YSZ) in the anode of a SOFC is believed to lead to microstructural evolution. Meanwhile, stress concentration and pore aggregation causes crack propagation in the anode. Both microstructural evolution and crack propagation have a significant impact on the performance of SOFCs. Based on theories of diffuse-interface and Ginzburg-Landau, an integrated phase field model is developed to couple electrode microstructural evolution and crack propagation in the anode. Interfacial diffusion of the phases is observed to lead to Ni particle coarsening. The triple phase boundary (TPB) is found to be affected by microstructural evolution and the crack propagation.