Preparation Characterization And Performance Research Of Cu-doped RP Layer Oxide Electrode Material

Solid Oxide Fuel Cell?SOFC?has the advantages of low pollution,fuel flexibility and distributed power generation,and is a kind of critical technology for clean energy utilization.To date,its development is mainly limited by high cost of traditional cathode materials and high work temperature?800-1000??.Therefore,developing intermediate-temperature SOFC?IT-SOFC?cathode materials and lowering work temperature have become hot topic of research.In recent years,as an advanced type of layered perovskite-like structure,Ruddlesden-Popper?RP?phase,whose general formula is A_n+1B_nO_3n+1,owns excellent electronic and ionic mixed conductivity,and it possesses higher oxygen surface exchange coefficient compared with perovskite phase.It has better oxygen ion transmission and structural stability than traditional cathode materials at intermediate-temperature.Hence the main contents are as follow:In this paper,a n=1 A₂BO₄ type oxide with a K₂Ni F₄ structure was first designed,following by Cu-doped at B site.By a facile citric-EDTA combustion method,La_1.6Sr_0.4Ni_1-xCu_xO₄?x=0,0.25?system cathode was prepared,and then characterization and electrochemical performance test were made.The results show Cu-doped improves the electrical conductivity and achieves proper thermal expansion which compared with electrolyte.Ni O+GDC/GDC/LSNi_1-xCu_xO₄?x=0,0.25?system single cells by anode-supported structure was fabricated.It is found that cell output power density improved from 260.7 m W·cm^-2 to 361.4 m W·cm^-2 and the polarization resistance decreased from 6.32?·cm² to 3.88?·cm² at 650?after Cu-doped,demonstrating cathodic polarization resistance is reduced when Cu is doped,promoting the oxygen reduction reaction process and improving the electrochemical performance.Afterwards,a n=2 two-layer RP phase oxide cathode material of La_0.25Sr_2.75Fe_2-xCu_xO₇?x=0,0.25,0.5?system was prepared and characterizated.Cu was doped at B site with different content.The research results show both the electrical conductivity and thermal expansion were upgraded to enhance comprehensive performance with the increase of Cu content.The single SOFC was fabricated by anode Ni O+GDC supported,GDC served as electrolyte,LSFe_2-xCu_xO₇?x=0,0.25,0.5?system used as cathode.The maximum power density of LSFe_2-xCu_xO₇?x=0.5?was up to 520.1 m W·cm^-2 and the polarization resistance decreased from 3.71?·cm²to 0.92?·cm².It is shown that Cu content with x=0.5owns best electrochemical performance and compared with n=1 RP phase cathode,the performance was also enhanced.In order to improve electrochemical performance of SOFC,based on the above cathodes,GDC was added in a weight ratio of 7:3 to prepare composite cathode,and their chemical compatibility and electrochemical test were made.The results show all composite cathode materials have good chemical compatibility and LSNi_1-xCu_xO₄?x=0.25?and LSFe_2-xCu_xO₇?x=0.5?based composite cathode material maximum power reach 465.2 m W·cm^-2and 554.2 m W·cm^-2 at 650?,respectively.The polarization impedance has also been significantly reduced.It is proved that the composite cathode is an ideal structure choice of cathode material and it can further enhance performance of RP layer oxide cathode.This paper has 34 figures,3 tables and 123 references.