Molecular Dynamics Simulation Of Solid Electrolyte YSZ

Solid oxide fuel cell?SOFC?is a device that converts chemical energy directly into electrical energy.It is a new generation of clean,efficient and environmentally friendly energy resources.SOFC usually has a"sandwich"structure consisting of an anode-electrolyte-cathode.The electrolyte film is sandwiched between the cathode and the anode to transport oxygen ion conduction and prevent electronic conduction.In fact,the reason why solid electrolyte can transport oxygen ions is that there are a large number of oxygen vacancies in it.On the one hand,the existence of oxygen vacancies provides a channel for the transport of oxygen ions.On the other hand,oxygen vacancies as a point defect will seriously affect the mechanical properties of electrolytes.Therefore,the oxygen transport and mechanical properties of yttrium stabilized zirconia?YSZ?,a kind of solid electrolyte,have been systematically studied by molecular dynamics?MD?.Firstly,the effects of temperature and yttrium oxide?Y₂O₃?doping concentration on the lattice constants of YSZ were analyzed by molecular dynamics method.The calculated results were compared with the experimental data and simulation results in the literature,and the validity of the used potential energy function and the corresponding parameters were verified.In addition,the coefficient of thermal expansion is calculated.Secondly,the diffusion properties of oxygen ions in YSZ materials were systematically studied by MD methods.The effects of temperature,Y₂O₃ doping concentration,loading state,electric field and grain boundary on the transport properties of oxygen ions were analyzed in detail,and the specific phenomena were explained from microscopic perspectives.Finally,the tensile and compressive processes of YSZ material were systematically simulated by molecular dynamics,and the stress-strain curves of YSZ in the conditions of different temperatures and doping concentrations were obtained.The phase transformation behavior of YSZ matrix material ZrO₂ during tensile process was analyzed.The Young's modulus under the corresponding conditions is obtained by linear fitting of the stress-strain data of the elastic stage and the fracture strength of YSZ is obtained directly from the stress-strain curve.The effects of temperature and doping concentration on Young's modulus and fracture strength are analyzed.