Electrochemical performance and stability of Sr-doped LaMnO_(3)-infiltrated yttria stabilized zirconia oxygen electrode for reversible solid oxide fuel cells

Porous Sr-doped lanthanum manganite–yttria stabilized zirconia(LSM–YSZ)oxygen electrode is prepared by an infiltration process for a reversible solid oxide fuel cell(RSOFC).X-ray diffraction and SEM analysis display that perovskite phase LSM submicro particles are evenly distributed in the porous YSZ matrix.Polarization curves and electrochemical impedance spectra are conducted for the RSOFC at 800 and 850C under both SOFC and SOEC modes.At 850℃,the single cell has the maximum power density of~726 mW/cm^(2)under SOFC mode,and electrolysis voltage of 1.35 V at 1 A/cm^(2)under SOEC mode.Fuel cell/water electrolysis cycle shows the cell has good performance stability during 6 cycles,which exhibits the LSM–YSZ oxygen electrode has high electrochemical performance and good stability.The results suggest that netw ork-like LSM–YSZ electrode made by infiltration process could be a promising oxygen electrode for high temperature RSOFCs.

Effect of calcination temperature on B-site vacancy content of La0.75Sr0.25Mn0.92△0.08O3-δperovskite

Lanthanum manganite with cation vacancies from nominal La（0.75）Sr（0.25）Mn（0.92）△（0.08）O（3-δ） nanocrystalline powder was successfully prepared at different calcination temperatures using the sol-gel method. X-ray diffraction shows that as the calcination temperature（T（Cal）） increases, the crystal particle diameter increases, but the B-site vacancy content decreases. According to a powder diffraction profile fitting technique and transmission electron microscopy results, the vacancy content can be estimated as 0.08,0.01, and 0.005 for T（Cal） = 1073,1273, and 1473 K, respectively. Magnetization versus temperature curves show that the magnetic transition temperatures, including the Curie temperature, are influenced by both B-site vacancies and double-exchange interaction between Mn^（3＋） and Mn^（4＋） cations. A core-shell model is proposed for vacancies located on the surfaces of the crystal particles. As an application, the magnetic moment angle θ（ij） between Mn^（3＋） and Mn^（4＋） cations on the surface, which decreases with decreasing vacancy content, can be obtained.

LSM particle size effect on the overall performance of IT-SOFC

In this paper, we reported the fuel cell performance with La0.8Sr0.2MnO3 （LSM）/Ce0.8Sm0.2O1.9 （SDC） composite cathode prepared from LSM powders of different particle sizes via the silk-printing technique. It was found that the change in particle size ofLSM nanoparticle from 40 to 90 nm resulted in an increase in the maximum power density from 132 to 228 mW/cm2 at 650 ℃ with H2 as fuel and O2 as oxidant. And the polarization resistance of the electrode decreased from 2.547 to 1.034 Ω.cm2. Concerning the particle size of electrode materials, a higher activity was anticipated with smaller particles because a large number of TPB or electrode surface sites along with a higher porosity could be developed. However, this study showed that the electrode prepared with particles of larger diameter had fine and uniform microstructure resulting in higher power density and lower overpotential, where homogeneous distribution of particles and pores was beneficial for increasing the electrochemical active area and the electronic conductivity of the electrodes as well as the gas diffusion for the reactants.