Preparation and Electrochemical Properties of Sr-doped K2NiF4-type Cathode Material Pr1.7Sr0.3CuO4 for IT-SOFCs

摘要

A novel K2NiF4-type oxide Pr1.7Sr0.3CuO4 (PSCu) is studied to obtain its electrochemical properties as the cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The PSCu cathode powder and Ce0.8Sm0.2O1.9 (SDC) electrolyte powder were synthesized by sol-gel method and glycine-nitrate method, respectively. The crystal structure of PSCu powder and PSCu-SDC composite powder were identified with X-ray diffraction (XRD). It is shown that PSCu belongs to tetragonal K2NiF4-type and has good chemical compatibility with SDC. The thermal expansion coefficient (TEC) of PSCu is close to that of SDC. The conductivity of PSCu tested with four-probe method exhibits a semiconductor-pseudometal transformation at 400-450 degrees C, where the maximum conductivity of 103.6 S cm(-1) is obtained. The polarization test indicates the area specific resistance (ASR) of PSCu decreases with increasing temperature, reaching 0.11 W cm(2) at 800 degrees C. The activation energy of oxygen reduction reaction during 600-800 degrees C is 1.19 eV. The single fuel cell performance test reveals the open circuit voltage (OCV) and resistivity of PSCu reduce with increasing temperature, but the power density ascends with increasing temperature. The maximal power density is 243 mW cm(-2) at 800 degrees C, and the corresponding current density and OCV are 633 mA cm(-2) and 0.77 V, respectively.