Search

A thin Ba3Ca1.18Nb1.82O9−δ (BCN18) membrane electrolyte was prepared by a novel and facile method on a NiO–BCN18 anode substrate. The interesting aspect of the method was the adoption of a in situ reaction of BaCO3, CaCO3, and Nb2O5 on the anode substrate to prepare a dense BCN18 membrane. The BCN18 membrane obtained, which was about 15 μm in thickness and showed high chemical stability against H2O and CO2, attained a high density after sintering at 1400°C. The elemental composition of the BCN18 membrane prepared was identified by energy-dispersive X-ray spectroscopy analysis. With La0.7Sr0.3FeO3−σ (LSF) as the cathode, the fuel cell performance with the structure of Ni–BCN18/BCN18/LSF was studied.

The sintering kinetics of the porous ceramics from natural diatomite is investigated by means of stepwise isothermal dilatometry (SID) accompanied with XRD, scanning electron microscope (SEM), and porosity measurement. We find that the isothermal shrinkage data from SID could be well analyzed to get kinetic parameters according to the empirical rate equation developed by Makipirtti–Meng, where Y is the fractional volume shrinkage during sintering process and n a dimensionless exponent. The apparent activation energy ΔE values obtained for 850°–1000°C and 1050°–1150°C are 911.8 and 610.5 kJ/mol, respectively. Correspondingly, the exponent n values for the two temperature ranges are also much different and can be served to reveal the morphology changing during the sintering process, which is well consistent with the SEM observation.

This article provides a brief review of the cathode reaction mechanisms in proton-conducting solid oxide fuel cells (H-SOFCs) and a comparative analysis of electrochemical performance and the ionic and electronic transport in cathode materials. The transfer of protons from electrolyte to triple phase boundaries (TPBs) and the diffusion of O−ad from catalytic sites to TPBs are proposed to be the rate-limiting steps for H-SOFCs, of which the latter is more related to the cathode components, microstructure, conducting species and electrical conductivity. The experimental and theoretical analyses also suggest that cathode materials with electron and proton conductivity present smaller polarisation resistances due to the ability of protons to transfer from the electrolyte into the bulk, which extends the reaction areas for protons and oxygen species to the entire gas/cathode surface.

BaCe 0.8− x Nb x Sm 0.2 O 3− δ ( x = 0, 0.05, 0.1) powders were prepared by a solid-state reaction method. After boiling in water for 3 h, the BaCe 0.8 Sm 0.2 O 3− δ powders obviously decomposed into CeO 2 and BaCO 3 while the other two powder samples containing Nb element in B site were hardly affected. According to thermal gravity analysis, the BaCe 0.8 Sm 0.2 O 3− δ powders displayed obvious reaction with CO 2 while the BaCe 0.7 Nb 0.1 Sm 0.2 O 3− δ powders were quite stable. Moreover, the sintered BaCe 0.7 Nb 0.1 Sm 0.2 O 3− δ sample exhibited a conductivity value of 0.0026 S/cm at 700 °C in wet hydrogen. A fuel cell with BaCe 0.7 Nb 0.1 Sm 0.2 O 3− δ as electrolyte was prepared by a suspension spray combining with in situ sintering method and tested in hydrogen from 600 °C to 700 °C. The peak power densities respectively reached 245 mW/cm 2 at 700 °C, 110 mW/cm 2 at 650 °C and 75 mW/cm 2 at 600 °C. The interface resistances were 0.31 Ω cm 2 at 700 °C, 0.43 Ω cm 2 at 650 °C and 1.2 Ω cm 2 at 600 °C, correspondingly.