Numerical Simulation Of Leakage Mechanism Of Low Temperature Solid Oxide Fuel Cell Based On Cerium Electrolyte

Solid Oxide Fuel Cells?SOFCs?are an energy conversion device that directly converts the chemical energy of fuel into electrical energy.Cerium-based electrolytes are the most commercially promising electrolyte materials for SOFCs.However,Ce⁴⁺is easily reduced to Ce³⁺in a reducing atmosphere,resulting in some electronic conductance and internal short-circuit currents in the cell,which greatly reduces the cell open circuit voltage?OCV?and cell efficiency.The experimental of the cell leakage characteristics will take a long time,and its steps are cumbersome.The leakage current and cell efficiency are difficult to be accurately measured in the experiment due to the limitations of the experiment itself.Therefore,it is very important to study the cell leakage characteristics by establishing the models with numerical simulation tools.It has very important research significance.In chapter 2,this article uses COMSOL and other tools to model solid oxide fuel cells.The second chapter first builds a single-layer electrolyte model of ion-electron mixed conduction based on cerium-based electrolyte,and then builds a double-layer electrolyte model with YSZ electron blocking layer on it.Relevant researches have been conducted on the influence of the temperature,electrolyte thickness,electron blocking layer thickness and other parameters on the cerium-based electrolyte leakage characteristics and cell efficiency.The study found that as the thickness of the barrier layer increases,the open circuit voltage increases and the leakage current decreases,but its maximum power will decrease.And the change trend of the cell efficiency curve is also divided into two obvious segments due to ohmic polarization.In the third chapter,based on the previous model,the in-situ generated electron barrier layer BZCY?specific chemical formula?double-layer electrolyte model is studied.The performance of leakage current,proton migration number,oxygen partial pressure,hydrogen partial pressure distribution,and cell efficiency were compared and studied.As a result,it was found that the OCV of the NiO-BZCY anode-supported cell was greater than that of the latter.This shows that the electron blocking layer formed at the anode-electrolyte interface can effectively prevent the reduction of the cerium-based electrolyte.In chapter 4,we establishes a composite electrolyte BZCY-SDC model based on the conduction mechanism and permeability mechanism of mixed ions of electrons,ions and protons.By analyzing different volume fractions,temperature,contact angle and other factors to analyze the battery leakage based on the composite electrolyte,proton conductivity,cell efficiency,etc.The results show that the composite electrolyte has a significant increase in open circuit voltage compared to pure cerium-based electrolytes.And with the increase of the contact angle angle,the contact surface of the SDC ball is expanded,which leads to a significant increase in oxygen ion and electron conductivity.The results also shows that it will decrease the proton transfer coefficient and proton current density.This paper has 28 figures,3 tables and 99 references.