物理化学学报2019，Vol.35Issue(3)：284-291,8.DOI:10.3866/PKU.WHXB201804171
氧分压对固体氧化物电解池性能的影响
Effect of Oxygen Partial Pressure on Solid Oxide Electrolysis Cells
摘要
Abstract
High-temperature (700-900 ℃) steam electrolysis based on solid oxide electrolysis cells (SOECs) is valuable as an efficient and clean path for large-scale hydrogen production with nearly zero carbon emissions,compared with the traditional paths of steam methane reforming or coal gasification.The operation parameters,in particular the feeding gas composition and pressure,significantly affect the performance of the electrolysis cell.In this study,a computational fluid dynamics model of an SOEC is built to predict the electrochemical performance of the cell with different sweep gases on the oxygen electrode.Sweep gases with different oxygen partial pressures between 1.01 x 103 and 1.0 x 105 Pa are fed to the oxygen electrode of the cell,and the influence of the oxygen partial pressure on the chemical equilibrium and kinetic reactions of the SOECs is analyzed.It is shown that the rate of increase of the reversible potential is inversely proportional to the oxygen partial pressure.Regarding the overpotentials caused by the ohmic,activation,and concentration polarization,the results vary with the reversible potential.The Ohmic overpotential isconstant under different operating conditions.The activation and concentration overpotentials at the hydrogen electrode are also steady over the entire oxygen partial pressure range.The oxygen partial pressure has the largest effect on the activation and concentration overpotentials on the oxygen electrode side,both of which decrease sharply with increasing oxygen partial pressure.Owing to the combined effects of the reversible potential and polarization overpotentials,the total electrolysis voltage is nonlinear.At low current density,the electrolysis cell shows better performance at low oxygen partial pressure,whereas the performance improves with increasing oxygen partial pressure at high current density.Thus,at low current density,the best sweep gas should be an oxygen-deficient gas such as nitrogen,CO2,or steam.Steam is the most promising because it is easy to separate the steam from the by-product oxygen in the tail gas,provided that the oxygen electrode is humidity-tolerant.However,at high current density,it is best to use pure oxygen as the sweep gas to reduce the electric energy consumption in the steam electrolysis process.The effects of the oxygen partial pressure on the power density and coefficient of performance of the SOEC are also discussed.At low current density,the electrical power demand is constant,and the efficiency decreases with growing oxygen partial pressure,whereas at high current density,the electrical power demand drops,and the efficiency increases.关键词
固体氧化物电解池/界面/氧分压/理论模型/计算流体动力学模拟Key words
Solid oxide electrolysis cell/Interface/Oxygen partial pressure/Theoretical model/Computational fluid dynamics分类
化学化工引用本文复制引用
侯权,关成志,肖国萍,王建强,朱志远..氧分压对固体氧化物电解池性能的影响[J].物理化学学报,2019,35(3):284-291,8.基金项目
The project was supported by the "Strategic Priority Research Program" of the Chinese Academy of Sciences (XDA02040600).中国科学院战略性先导科技专项(XDA02040600)资助项目 （XDA02040600）
