Magnetic Alignment of Anode Microstructure in Solid Oxide Fuel Cell. Issue 2 (31st January 2019)

• Record Type: Journal Article
• Authors: Nagato, Keisuke; Shintani, Kodai; Shimura, Takaaki; Shikazono, Naoki; Nakao, Masayuki
• Is Part Of: Journal of the Electrochemical Society. Volume 166:Issue 2(2019)
• Page Start: F144
• Page End: F148
• Publication Date: 2019-01-31
• Subjects: Fuel Cells - Solid oxide -- anode -- magnetic alignment -- solid oxide fuel cell; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.1071902jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Polarization resistance of solid oxide fuel cell electrodes consists of resistances due to mass transfer and chemical reaction. Therefore, higher ion conductivity, electron conductivity, and gas diffusivity and larger triple-phase boundary (TPB) density lead to lower polarization resistance. To increase effective conductivities and diffusivity, tortuosity factors in each mass-transfer path should be reduced. In this study, magnetic alignment method is developed to align the mass-transfer paths in the electrode microstructure. Since Ni as an electron-conducting material in anode has high magnetic permeability, the particles are polarized and aligned by a magnetic field. Therefore, the tortuosity factors can be reduced. In addition, this Ni alignment is expected to reduce the tortuosity factors of yttria-stabilized zirconia (YSZ) and pore phases as well. However, there is a risk for a decrease in TPB density. The effect of magnetic field on resultant microstructure and polarization resistance of Ni-YSZ anode are investigated by impedance measurement of anode symmetrical cells and by reconstruction of three-dimensional microstructure. The tortuosity factors of Ni and YSZ decreased and TPB density decreased by the magnetic field. As a result, the polarization resistance of anode was kept nearly unchanged. The effect of reducing Ni volume fraction is also investigated.