Advances in Cathode Materials for Solid Oxide Fuel Cells: Complex Oxides without Alkaline Earth Metal Elements

Abstract

Solid oxide fuel cells (SOFCs) represent one of the cleanest and most efficient options for the direct conversion of a wide variety of fuels to electricity. For example, SOFCs powered by natural gas are ideally suited for distributed power generation. However, the commercialization of SOFC technologies hinges on breakthroughs in materials development to dramatically reduce the cost while enhancing performance and durability. One of the critical obstacles to achieving high‐performance SOFC systems is the cathodes for oxygen reduction reaction (ORR), which perform poorly at low temperatures and degrade over time under operating conditions. Here a comprehensive review of the latest advances in the development of SOFC cathodes is presented: complex oxides without alkaline earth metal elements (because these elements could be vulnerable to phase segregation and contaminant poisoning). Various strategies are discussed for enhancing ORR activity while minimizing the effect of contaminant on electrode durability. Furthermore, some of the critical challenges are briefly highlighted and the prospects for future‐generation SOFC cathodes are discussed. A good understanding of the latest advances and remaining challenges in searching for highly active SOFC cathodes with robust tolerance to contaminants may provide useful guidance for the rational design of new materials and structures for commercially viable SOFC technologies.

Evolution of the electrochemical interface in high-temperature fuel cells and electrolysers

“…In spite of this, recent investigations could not establish any clear correlation between the SrO segregation and the surface oxygen exchange rate on RP-type O2-electrodes 15,35 , suggesting that our understanding of the SOC electrode process related to surface reorganisation is still incomplete. Nonetheless, recent reports suggest that surface segregation in perovskites may be minimised by adequate choice of A-site cations and perovskite defect chemistry 31,36,37 .…”

Corn-cob like nanofibres as cathode catalysts for an effective microstructure design in solid oxide fuel cells

“…As the cathode reaction only take place at the three-phase boundary (TPB) sites where LSM-YSZ-gas phase meeting together, the microstructure design is an important process to increase the TPB sites from larger active sites and better connectivity for optimizing the cathode electrochemical reaction. [13][14][15] Many efforts have been made to optimize the microstructure of the cathode in order to gain an satisfied polarization resistance by changing various mixed ion/electron conductors, [16][17] production methods (infiltration, impregnation), [18][19][20] preparation conditions (temperature, time , etc), 21 and material morphology (particle size and shape).…”

Структура, стабильность и термомеханические свойства Ca-замещенного Pr-=SUB=-2-=/SUB=-NiO-=SUB=-4+delta-=/SUB=-

“…В случае электрода со смешанной кислород-ионной и электронной проводимостью поляризация связана со следующими стадиями [2,3]: адсорбцией из газовой фазы и диффузией атомарного кислорода по поверх-ности электрода, восстановлением атома кислорода с образованием иона О 2− , диффузией иона кислорода сквозь частицы электрода со смешанной проводимо-стью и переходом иона через границу раздела элек-тролит/смешанный проводник. Таким образом, в каче-стве кислородных электродов предпочтительно исполь-зовать материалы, обладающие как высокой смешанной (кислород-ионной и электронной) проводимостью, так и высокими значениями коэффициента диффузии и кон-станты поверхностного обмена.…”

“…Соединения типа Ln 2 NiO 4+δ при комнатной темпе-ратуре кристаллизуются в структурном типе K 2 NiF 4 с пространственной группой Fmmm или Bmab [1,2]. Орторомбические искажения элементарной ячейки уве-личиваются с уменьшением радиуса редкоземельного элемента, при этом растет содержание сверхстехиомет-рического кислорода (δ), компенсирующего напряжения в структуре [4].…”