Design, Synthesis And Electrochemical Performance Of Composite Cathode Based On Pr₂CuO₄

A major problem retarding the development of intermediate temperature solid oxide fuel cells（IT-SOFC）is the poor catalytic activity of cathode materials in the intermediate and low temperature regions.Multicomponent doping and preparation of composite electrode materials are effective means to solve this problem.Copper based A₂BO₄structure oxides have excellent oxygen transport and electronic conductivity.They are a kind of cathode materials with great development potential in future.In this study,Pr₂Cu O₄was designed as the research object,and the electrochemical properties were optimized by means of composite and multicomponent doping,and its possibility as IT-SOFC cathode material was investigated.Pr₂Cu O₄-Pr₆O₁₁composite was synthesized by improved sol-gel method（one-pot synthesis method）and its phase formation mechanism was discussed.The study showed that one-step self-assembly synthesis of Pr₆O₁₁-modified Pr₂Cu O₄composites can be achieved by adjusting the ratio of raw materials.Compared with the materials prepared by mechanical mixing method,the particles synthesized by the one-pot method have smaller particle size and larger specific surface area,obvious lattice defects were generated at the two-phase interface.The modification of Pr₆O₁₁can significantly improve the oxygen surface exchange capacity of Pr₂Cu O₄.The polarization resistance of the material with the best composite ratio of Pr₂Cu O₄:Pr₆O₁₁=8:2 is 0.07Ωcm~2at700℃,and the peak power density of the anode support battery assembled with this cathode material reach to 1.07 W cm^-2.Pr₂Cu O₄-Ce O₂-Cu O three-phase composites were synthesized by one pot synthesis method.The test results show that Ce O₂and Cu O effectively improve the surface oxygen exchange capacity of Pr₂Cu O₄and further accelerate the oxygen reduction reaction rate of cathode material.Compared with Pr₂Cu O₄-Pr₆O₁₁,Pr₂Cu O₄-Ce O₂-Cu O has lower polarization resistance,which is 0.11Ωcm~2at 600℃.The anode-supported single cell assembled with Pr₂Cu O₄-Ce O₂-Cu O as the cathode has a peak power density of 1.3 W cm^-2at 700℃,and the cell can operate stably for 130 hours at a load voltage of 0.5 V without significant current decay.In view of the good electrochemical properties of the multi component composites,the(La_0.2Pr_0.2Nd_0.2Sm_0.2Gd_0.2)₂Cu O₄high entropy oxide cathode material（HE-LCO）containing 5 kinds of rare earth ions was synthesized by sol-gel method.At 700℃,the polarization resistance of HE-LCO is 0.52Ωcm~2,the peak power density of anode supported single cell assembled with HE-LCO is 552 m W cm^-2,and there is no obvious performance degradation within 70 hours.By compounding with GDC,the electrochemical performance of HE-LCO-GDC composite cathode is further improved.This study explores the feasibility of A₂BO₄structure high-entropy oxides as SOFC cathodes for the first time,which provides ideas for the development of new SOFC cathode materials.