Thermal expansion and electrochemical properties of La0.7AE0.3CuO3−δ (AE=Ca, Sr, Ba) cathode materials for IT-SOFCs

Abstract

Alkaline earth metals (Ca, Sr, Ba) substituted lanthanum copper oxides were investigated to evaluate their potentials as cathode materials for intermediate temperature solid oxide fuel cell (IT-SOFC). The crystal structure, thermal expansion and electrochemical performance of La 1−x AE x CuO 3−δ (x=0.3, AE=Ca, Sr, Ba) were studied by X-ray diffraction, thermal dilatometer and impedance spectra, respectively. By lowering the size of the A-site cation in ABO 3 perovskite, a lower thermal expansion and polarization resistance were obtained for Ca-doped LaCuO 3−δ cathode which showed an area specific resistance of 0.19 Ω cm −2 under open circuit potential conditions at 800°C, and a polarization overpotential of 52 mV at a current density of 0.1 A/cm 2 at 700°C, being a potential candidate of cathode material for IT-SOFCs.

Characterization of Pr0.5A0.5Fe0.9W0.1O3−δ (A = Ca, Sr and Ba) as symmetric electrodes for solid oxide fuel cells

“…The value increases from Ca to Sr with the increase in ionic radii, which could be related to the enhancement of the ionic character of the A–O band. 23 All in all, the symmetric electrode PAFW exhibits good thermal compatibility with the LSGM electrolyte at operating temperatures.…”

“…For example, La 0.7 Ca 0.3 CuO 3− δ showed the lowest thermal expansion and highest electrode activity among La 1− x AE x CuO 3− δ ( x = 0.3 and AE = Ca, Sr, Ba). 23 The structural symmetry gradually distorts and the electrical conductivity and the concentration of oxygen active sites on the surface decrease with the ionic radius from La to Sm while the Ln–O band energy increases. 24 Zhang et al 25 reported that the conductivity and electrochemical performance of Ln 0.5 Sr 0.5 Fe 0.9 Mo 0.1 O 3− δ (Ln = lanthanide, including La, Pr, Nd, Sm, Gd) followed the sequence of La > Nd > Pr.…”

Evaluation of Nd0.8−xSr0.2CaxCoO3−δ(x = 0, 0.05, 0.1, 0.15, 0.2) as a cathode material for intermediate-temperature solid oxide fuel cells

“…In perovskite structure, the electronic conductivity is higher than the ionic conductivity and therefore is the dominant force. 5,36 The joint action of the two compensation modes leads to the phenomenon that the conductivity decreases with the increase of temperature. With the increase of temperature, ion conduction begins to play a role, and the effect of electron conduction weakens.…”

“…Among available materials, LaCoO 3− δ has attracted attention due to its impressive ORR activity and good proton–ion conductivity. 5 However, Co-based materials have a high coefficient of thermal expansion (CTE), which results in high thermal stress at high temperature and limits their further development. 6 High thermal stress can loosen the bond between cathode and electrolyte, leading to cathode detachment and cell failure.…”