Топливные элементы

The dependence of oxygen stoichiometry on the oxygen partial pressure and the temperature for La- and Nb-doped strontium ferrite La0.4Sr0.6Fe0.95Nb0.05O3 – δ (LSFNb5) was studied by quasi-equilibrium oxygen release (QEOR) method. The equilibrium diagram in the coordinates “T – lg(pO2 ) – 3 – δ” in the temperature range of 700–900°C and oxygen partial pressures pO2 = 10–4 – 0.2 atm was obtained. The range of stoichiometry deviation was determined, and the thermodynamic parameters of the oxygen release process were analyzed.

The methodology for preparing precursors for the fabrication of the anode-supported tubular substrates from NiO/YSZ composite was developed. The optimal amount of the pore-forming agent to get the well-developed porosity in the supporting anode was determined. The relationship between the fabrication methods of the anodic and electrolytic functional layers in SOFCs was demonstrated.

In this work, the material La0.9Sr0.1Sс0.4Mn0.6O3 – δ was synthesized using the citrate-nitrate method. The electrochemical characteristics of the material were studied using impedance spectroscopy on symmetric cells and compared with the model Pt cathode contacting the proton-conducting electrolyte. It was shown that the polarization resistance of the investigated material is approximately two orders lower than that of the model Pt electrode.

High synthesis temperatures and sintering-active powders are required to obtain electrolyte materials with a pyrochlore structure. The smaller the particle size, the higher the density of the resulting samples is. The synthesis of highly dispersed oxide powders of doped lanthanum zirconate was carried out using a series of methods to determine the influence of experimental conditions on the microstructure of the resulting powders and ceramics.

The electrochemical characteristics of the tubular solid oxide fuel cells (SOFC) and the symmetrical anodic cells with conventional nickel-cermet and modified nickel-cobalt cermet anodes were studied using voltammetry, electrochemical impedance spectroscopy, and distribution of relaxation time analysis. The tubular SOFC with the modified anode exhibited higher power output and demonstrated lower power loss at reduced temperatures, which is attributed to higher electrical conductivity and lower activation energy of the anodic electrode reaction.

Electrode processes occurring in a tubular solid oxide fuel cell were studied using the distribution of relaxation time (DRT) method. The conclusion about the localization of the processes and their nature was made by analyzing the capacitances of the processes and changing their activation energy because of sequential activation of the electrodes. The greatest contribution to the total resistance of the cell was made by cathodic processes at the electrode-contact and electrode-electrolyte boundaries.