Solid oxide fuel cell anode surface modification by magnetron sputtering of NiO/YSZ thin film

Abstract

IntroductionA ceramic-metal (cermet) composite of Ni and yttria-stabilized zirconia (YSZ) is the most common anode material of solid oxide fuel cells (SOFC) operating at a temperature of 800-1000 °C. However, the desire to create a commercial SOFC requires to mitigate the problem, associated with a high operating temperature. In turn, the lower operating temperature would increase polarization of electrodes and ohmic resistance of electrolyte. The ohmic resistance can be decreased either by using ultra-thin electrolytes, or new materials with higher ionic conductivity at lower temperatures [1,2]. Polarization losses of the anode can be reduced by creating new alternative materials or by nanostructuring commonly used 4]. The second approach seems to be the most promising for improving the SOFC characteristics. First, conventional NiO/YSZ cermet is cheaper than other materials, chemically stable in a reducing atmosphere at high temperatures and has thermal expansion coefficient close to that of YSZ electrolyte [5]. Second, it is known that the electrochemical reaction at the anode occurs at a three-phase boundary (TPB), the area of contact between the metal, the electrolyte and the working gas. Therefore, the electrode reaction rate and, hence, its efficiency is determined by the TPB length. The formation of nanoporous anode structure will significantly increase the TPB length. At that, the nanostructuring of the whole anode substrate is not required, since the coarse anode facilitates the rapid diffusion of fuel gas to the active reaction area and removal of reaction products out from the anode [6]. Formation of the nanostructured anode functional layer

Low-temperature preparation and investigation of electrochemical properties of SFM/CGO composite electrode

“…[29] reported similar results for doped ceria when the number of oxygen vacancies increased due to replacement of Ce with different rare earth elements. 200) planes in the cubic fluorite structure are known as a plane with the lowest surface energy and fastest out-of-plan growth [30,31], respectively. Adopting of the 80 W for applied radio frequency power provides high enough mobility in sputtered particles, and according to the proposed mechanism for film growth by Mahieu et al [32], it is categorized in zone T deposition.…”