Review on process-microstructure-performance relationship in ALD-engineered SOFCs

Abstract

Solid oxide fuel cells (SOFCs) are promising candidates for next-generation energy conversion devices, and much effort has been made to lower their operating temperature for wider applicability. Recently, atomic layer deposition (ALD), a novel variant of chemical vapor deposition, has demonstrated interesting research opportunities for SOFCs due to its unique features such as conformality and precise thickness/doping controllability. Individual components of SOFCs, namely the electrolyte, electrolyte-electrode interface, and electrode, can be effectively engineered by ALD nanostructures to yield higher performance and better stability. While the particulate or porous structures may benefit the electrode performance by maximizing the surface area, the dense film effectively blocks the chemical or physical shorting even at nanoscale thickness when applied to the electrolyte, which helps to increase the performance at low operating temperature. In this article, recent examples of the application of ALD-processed nanostructures to SOFCs are reviewed, and the quantitative relationship between ALD process, ALD nanostructure and the performance and stability of SOFCs is elucidated. Abbreviations

Noble‐Metal‐Assisted Fast Interfacial Oxygen Migration with Topotactic Phase Transition in Perovskite Oxides

“…For practical applications related to oxygen migration such as SOFCs, the morphology of noble‐metal layer on oxides is also dependent on external parameters and greatly influences the efficiency of charge transfer and ion diffusion. [ 42 ] Nanostructured Pt catalysts by atomic‐layer deposition [ 43 ] can improve SOFC performance at low temperatures owing to a high triple‐phase‐boundary density [ 44 ] and electrocatalytic surface nanoionics. [ 45 ] In YSZ/Pt electrode of SOFCs, the fully mixed cermet interlayers provide thermal stability of the Pt particles and large density of catalytically active sites.…”

Design of Ordered Mesoporous CeO2–YSZ Nanocomposite Thin Films with Mixed Ionic/Electronic Conductivity via Surface Engineering

“…Surface engineering may lead to further improvements in the properties of mesoporous oxides. The accessibility of the free surface through the porosity enables its effective modification, e.g., by functionalization, deposition of thin coatings, or incorporation of guest species, such as metal nanoparticles. − A common approach is surface coating via atomic layer deposition (ALD). − ALD allows preparing conformal and uniform coatings on complex surfaces, with precise control over their thickness. − It is therefore often used in surface engineering of nanostructured materials for energy applications. ,− One of the benefits of ALD-derived thin surface coatings is that the deposition of a simple binary oxide, such as Al 2 O 3 or SiO 2 , can help increase the thermal stability of mesoporous materials, − whose structure often tends to collapse at elevated temperatures. Surface modification via ALD is also successfully applied to protect/stabilize cathode materials in lithium-ion and solid-state batteries − or to improve the performance of solid oxide fuel cells. − Apart from that, surface engineering of complex nanostructures using ALD allows developing innovative mixed-conducting composites.…”

Surface decorations to abrupt change performance, robustness, and stability of electrodes for solid oxide cells

“…ALD nanostructure deposition could be either particulate, network, or dense film structures depending on the film growth stage. It can achieve high conformability over very high aspect structures, continuous and pinhole‐free deposition at a thickness of several nanometers 33,34 . Apart from being frequently used for semiconductor processing, ALD has also been used for the deposition of conformal layers in SOFC electrodes, 35,36 providing a significant enhancement in the SOFCs performance.…”