Preparation And Performance Of Medium Temperature Solid Oxide Fuel Cells Based On Semiconductor Heterogeneous Interfaces

Solid oxide fuel cells（SOFCs）are a promising technology in the field of solid chemical cells due to their high energy conversion efficiency and environmental friendliness.However,their commercial viability is limited by the high temperature required to maximize their performance.Introducing semiconductor materials into the fuel cell via semiconductor ionology can enable the fuel cell to perform at excellent levels at intermediate temperatures between 400℃and 600℃.This presents a new avenue for promoting fuel cell technology in commercial applications.In this study,three intermediate temperature solid oxide fuel electrolytes based on semiconductor heterojunction were designed and tested.（1）Studies on p-NaCrO₂ and n-CeO₂ composite solid electrolytes show that these two materials are difficult to function independently in fuel cell atmosphere.However,their combination significantly improved the performance of the cell,achieving ionic conductivity of 0.173 S·cm^-1 and power density output of 627m W·cm^-2 at a molar ratio of 4:6.TEM images revealed the presence of numerous heterogeneous interfaces,which led to increased oxygen vacancy content and enhanced ion transport,as confirmed by XPS images and theoretical calculations.P-N heterojunction was found to change the short circuit of the semiconductor in fuel cell atmospheres and promote ion transport.（2）Studies on CaSnO₃ and n-ZnO composite solid electrolytes show that although these two materials can be used as electrolytes independently for fuel cells,the composite cell has better performance.At a mass ratio of 2:8,the composite material achieved a performance output of 700 m W·cm-2 and an ionic conductivity of 0.201S·cm^-1 at 550℃.EIS tests revealed smaller volume resistance and grain boundary resistance,facilitating ion transport within the cell.Stability tests showed the cell could sustain an output of 200 m W·cm^-2 for up to 3 hours.The metal-semiconductor Schottky junction formed by semiconductor ZnO and electrode metal layer inhibited internal electron conduction and acted as a rectifier,further enhancing the performance.（3）Studies on Ni-doped CeO₂ solid electrolytes show that Ni doping ratio affects the performance of cells.XRD,EDS,and TEM images confirmed successful Ni doping into the CeO₂ lattice.Electrochemical tests achieved a performance output of 494m W·cm^-2 and an ionic conductivity of 0.182 S·cm^-1 at 550℃when the doping ratio was 0.1.EIS tests revealed smaller ohm impedance,grain boundary impedance,and concentration polarization impedance inside the cell.Experiments showed the presence of metal-semiconductor Schottky heterojunction inside the fuel cell,where the local electric field inhibited electron transmission inside the cell at high temperatures.Cell stability tests demonstrated that the cell could sustain an output of 100 m W·cm^-2 for up to 24 hours.