Pr_(1-x)SrCo_(0.5)Ni_(0.5)O_(4+δ)阴极材料的合成及电化学性质

Synthesis and Electrochemical Properties of Pr_(1-x)SrCo_(0.5)Ni_(0.5)O_(4+δ) Cathode Materials

采用固相法合成中温固体氧化物燃料电池(IT-SOFC)阴极材料Pr_(1-x)SrCo_(0.5)Ni_(0.5)O_(4+δ)(P_(1-x)SCN,x=0.00,0.05,0.10,0.15,0.20),并对材料的物相、热膨胀系数(TEC)、电导率、电极的微观形貌以及电化学性质进行表征。XRD结果表明,该材料形成单一的K_2NiF_4结构,空间群为I4/mmm,并与电解质材料Ce_(0.9)Gd_(0.1)O_(1.95)(CGO)具有良好的高温化学相容性。碘量法分析表明随着Pr离子缺位浓度增加,P_(1-x)SCN中Co/Ni离子平均化合价随着x的增加而升高,至x=0.10后逐渐降低,而氧空位含量逐渐升高。引入Pr离子缺位使材料的电导率明显提高,其中P_(0.90)SCN在700℃空气中电导率值为309 S·cm^(-1)。TEC测试结果显示,随着Pr缺位的增加,热膨胀系数逐渐增大,最大值为1.51×10^(-5)K^(-1)。交流阻抗谱(EIS)测试结果表明,Pr缺位明显降低了电极的极化阻抗值,P_(0.90)SCN阴极在700℃空气中的极化阻抗值为0.21Ω·cm^2。电解质支撑NiO-CGO/CGO/P_(0.90)SCN单电池在700℃最大输出功率密度为197.8 mW·cm^(-2)。

Intermediate temperature solid oxide fuel cells (IT-SOFCs) cathode materials Pr1-xSrCo0.5Ni0.5O4+δ(P1-xSCN, x=0.0, 0.05, 0.10, 0.15, 0.20) are synthesized by solid-state reaction method. The phase, thermal expansion coefficient (TEC), conductivity, electrode morphology and electrochemical properties are characterized. XRD results show that the oxides crystallize in a single K2NiF4 structure with a space group of I4/mmm. The cathode materials exhibited good high temperature chemical compatibility with electrolyte Ce0.9Gd0.1O1.95 (CGO). Iodometry analysis shows that with the increase of Pr3+ vacancy concentration, the average valence of Co/Ni ions in oxides increased stepwise with the increase of x and then decreased after x=0.10, while the content of oxygen vacancy increased gradually. Introducing Pr3+ vacancy significantly improved the conductivity of the material. The highest conductivity of 309 S·cm^-1 was found in P0.90SCN at 700 ℃ in air. The thermal expansion measurement results show that TEC increased with the increase of Pr3+ deficiency, and the maximum value is 1.51×10^-5 K^-1. Electrochemical impedance spectroscopy (EIS) measurements show that Pr vacancy significantly reduced the polarization resistance of the electrode, and the smallest polarization resistance of 0.21 Ω·cm2 was obtained on P0.90SCN cathode at 700 ℃ in air. The maximum output power density of electrolyte supported single cell NiO-CGO/CGO/P0.90SCN was 197.8 mW·cm^-2 at 700 ℃.