Microstructural Characterization Of Solid Oxide Fuel Cell Electrodes By Numerical Simulations

Solid Oxide Fuel Cells(SOFCs)can directly convert the chemical energy in hydrocarbon fuels into electrical energy at higher operating temperatures without having to pass through other complex energy conversion devices and purification devices,resulting in high power generation efficiency.The amount of harmful gases such as CO2 and NOx generated per unit of power generation is also significantly lower than that of traditional thermal power generation technology.Therefore,SOFC has become the focus of people's research.At present,the plate anode support type SOFC has become the mainstream research direction due to its higher bulk power density.Through research,it is found that the microstructure parameters of the porous anode have a very important influence on the anode-supported plate-type fuel cell,and even each parameter will have a certain impact on the performance of the battery.Since the SOFC is in a high-temperature,airtight environment during operation,this makes it difficult to measure the internal performance and parameters of the battery under operating conditions.The experimental cost is high and even under some conditions it cannot be completed.Therefore,the use of numerical simulation methods instead of experimental methods can reveal the internal working conditions of the battery and provide theoretical support for future applications.The paper starts with the study of the microstructure parameters of SOFC,performs a steady-state modeling analysis,and quantifies the influence of microstructure parameters on battery performance.The main research contents of the paper are as follows:(1)Using COMSOL software to establish a mathematical model for single cell operation,to simulate the steady-state operating conditions of SOFC,to study the electrochemical performance under different operating conditions,and to simulate the results and experimental results of different operating conditions The following analysis and comparison.The results show that the higher the operating temperature,the higher the output power of the SOFC and the better the electrochemical performance.The corrected analog values agree well with the experimental results,and the maximum error does not exceed 10%.(2)According to the mathematical model of the single cell established in the software,the influence of porosity,tortuosity,pore size,and particle size on the performance of the battery is systematically analyzed,and the concentration distribution and fuel of the gas in the electrode are combined with each microstructure parameter.The effects of utilization and current density distribution.The results show that with the increase of porosity,the maximum output power density increases first and then decreases,and the maximum value is obtained when the porosity is 0.4.The larger the aperture,the smaller the tortuosity,and the better the gas diffusion effect in the electrode.The smaller the concentration gradient distribution is,the smaller the particle size is,the higher the current density in the electrode is,and the higher the output power is,the smaller the particle size is.When the pore size is greater than 0.5 ?m and the tortuosity is less than 2,the diffusion effect is greatly reduced.At 0.2 ?m,the maximum power density is 0.440 W/cm2.(3)Based on the results of single-factor studies of microstructure parameters,the three microstructural parameters of porosity,tortuosity,and pore size were fitted to the data.The fitting result was that the porosity distribution range was 0.2-0.6 for each The electrochemical properties at the time of the change of other microstructure parameters under the particle size were studied.The results show that when the anode support layer and the functional particle size are the same as the porosity,the microstructure parameters at the maximum output power are: 0.2 ?m particle size,0.5 porosity,1.29 twist degree,0.19 ?m pore size,and 1.58 times the maximum power density.When the anode support layer and functional layer size and porosity are different,the microstructure parameter combination when the output power is the maximum is: support layer particle size 0.5 ?m,porosity 0.5,tortuosity 1.29,pore size 0.6 ?m,functional layer particle size 0.2 ?m,porosity 0.25,tortuosity,aperture 0.11 ?m,maximum power density increase 1.78 times.