Double layer structure in solid oxide fuel cell anode/electrolyte interfaces: A Monte Carlo study

The double layer structure of solid oxide fuel cell anode/electrolyte interfaces is simulated by Markov Chain Monte Carlo methods. A case study is carried out on lanthanum strontium vanadate (LSV)/yttria-stabilized zirconia (YSZ). The density of oxygen vacancies directly adjacent to the LSV/YSZ interface is one order of magnitude higher than the bulk value of YSZ. The spatial variation of oxygen vacancies in the double layer region exhibits exponential decay behaviour. The double layer undergoes pronounced relaxations when the interfaces are under anodic biases ranging from 0 to 150 mV. The results indicate that 70–80% of the oxygen vacancies are immobilized in the Helmholtz–Perrin layer. The rationale presented in this work has wide applications on elucidating anodic reaction mechanisms and potential distributions across anode/electrolyte interfaces.

Graphical abstractThe oxygen vacancy distribution in YSZ in the double layer region.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch Highlights► Two-dimensional oxygen vacancy diagram and density plots in the YSZ side of the double layer. ► High interfacial oxygen vacancy concentration that is 10 times than the bulk value. ► Exponentially decaying oxygen vacancy density profile across the double layer. ► Thicknesses of 0.5 to 0.8 nm for the Helmholtz–Perrin layer; about 2 nm-thick for the double layer region. ► 70–80% of the oxygen vacancies composing the Helmholtz–Perrin layer.