In this paper, selected layered cuprates with La_2-x(Sr,Ba)_xCuO_4-δ formula are evaluated as candidate cathode materials for Solid Oxide Fuel Cells. Two synthesis routes, a typical solid state reaction and a sol-gel method yield well-crystallized La_1.5Sr_0.5CuO_4-δ, La_1.6Ba_0.4CuO_4-δ and La_1.5Sr_0.3Ba_0.2CuO_4-δ materials having tetragonal I4/mmm space group, but differing in morphology of the powder. Fine powders obtained using sol-gel route seem to be more suitable for preparation of the porous cathode layers having good adhesion on the solid electrolyte, but powders obtained after the solid state route can be also successfully utilized. Investigations of structural and transport properties, the oxygen nonstoichiometry and its change with temperature, thermal expansion, as well as chemical and thermal stability are systematically performed, to evaluate and compare basic physicochemical properties of the oxides. At room temperature the average valence state of copper is found to be in 2.2–2.35 range, indicating oxygen deficiency in all of the compounds, which further increases with temperature. The conducted high-temperature X-ray diffraction tests reveal moderate, but anisotropic thermal expansion of La_2-x(Sr,Ba)_xCuO_4-δ, with higher expansion at temperatures above 400 °C occurring along a-axis, due to the oxygen release. However, the corresponding chemical expansion effect is small and the materials possess moderate thermal expansion in the whole studied temperature range. All compounds show relatively high electrical conductivity at the elevated temperatures, related to the Cu²⁺/Cu³⁺ charge transfer, with the highest values recorded for La_1.5Sr_0.5CuO_4-δ. Comprehensive studies of chemical stability of the selected La_1.5Sr_0.5CuO_4-δ material with La_0.8Sr_0.2Ga_0.8Mg_0.2O_3-δ solid electrolyte revealed complex behavior, with stability being dependent apart from temperature, also on morphology of the powders. A model describing such behavior is presented. While it is possible to minimize reactivity and characterize electrochemical properties of the La_1.5Sr_0.5CuO_4-δ-based cathode layer, usage of the buffer layer is indispensable to maintain full stability. It is shown that mutual chemical compatibility of La_1.5Sr_0.5CuO_4-δ and commonly used La_0.4Ce_0.6O_2-δ buffer layer material is excellent, with no reactivity even at 1000 °C for prolonged time. Laboratory-scale fuel cell with the La_1.5Sr_0.5CuO_4-δ cathode sintered at the optimized temperature is able to deliver 0.16 W cm⁻² at 800 °C while fueled with wet hydrogen.

在本文中，选择具有La _2-x（Sr，Ba）_x CuO4 _-δ分子式的层状铜酸盐作为固体氧化物燃料电池的候选阴极材料。两种合成途径（典型的固态反应和溶胶-凝胶法）可得到具有四方晶的结晶良好的La _1.5 Sr _0.5 CuO4 _-δ，La _1.6 Ba _0.4 CuO4 _-δ和La _1.5 Sr _0.3 Ba _0.2 CuO4 _-δ材料。I 4 /毫米空间群，但粉末的形态不同。使用溶胶-凝胶法获得的细粉似乎更适合于制备在固体电解质上具有良好粘附性的多孔阴极层，但是固态路线之后获得的粉也可以成功地利用。系统地研究了结构和运输性质，氧的非化学计量及其随温度，热膨胀以及化学和热稳定性的变化，以评估和比较氧化物的基本物理化学性质。在室温下，发现铜的平均价态在2.2–2.35范围内，这表明所有化合物中的氧缺乏都随着温度的升高而进一步增加。进行的高温X射线衍射测试表明，_2-x（Sr，Ba）_x CuO4 _-δ，由于氧气释放，在高于400°C的温度下沿a轴发生更高的膨胀。然而，相应的化学膨胀作用很小，并且材料在整个研究温度范围内具有适度的热膨胀。所有化合物在高温下均显示出相对较高的电导率，与Cu ²⁺ / Cu ³⁺电荷转移有关，其中La _1.5 Sr _0.5 CuO4 _-δ的记录值最高。精选La _1.5 Sr _0.5 CuO4 _-δ的化学稳定性的综合研究具有La _0.8 Sr _0.2 Ga _0.8 Mg _0.2 O3 _-δ固体电解质的材料显示出复杂的行为，其稳定性取决于温度，还取决于粉末的形态。提供了描述这种行为的模型。虽然可以使基于La _1.5 Sr _0.5 CuO4 _-δ的阴极层的反应性最小化并表征其电化学性质，但是必须使用缓冲层来保持完全的稳定性。结果表明，La _1.5 Sr _0.5 CuO4 _-δ与常用La _0.4 Ce _0.6的相互化学相容性。O2 _-δ缓冲层材料非常好，即使在1000°C下长时间也没有反应性。在优化温度下烧结的La _1.5 Sr _0.5 CuO4 _-δ阴极的实验室规模燃料电池，在以湿氢为燃料的情况下，能够在800°C下提供0.16 W cm ^-2的燃料。