Development of porous anode layers for the Solid Oxide Fuel Cell by plasma spraying

Kurzfassung

Solid Oxide Fuel Cells (SOFC) are efficient energy converting systems transforming chemical energy directly into electrical energy and heat at elevated temperatures. A fuel cell typically consists of three layers that are cathode, electrolyte and anode. This paper focuses on development of the anode layer, where the oxidation of the fuel gas by reaction with oxygen ions takes place. The composite (cermet) anode, developed by thermal spraying, consisted of nickel and YSZ. The effect of different plasma spraying technologies on the micro structural characteristics and the electrochemical behavior of the anode layer were investigated. Coatings were fabricated by spraying nickel-coated graphite or nickel oxide with YSZ using a Triplex II plasma torch under atmospheric conditions as well as a standard F4-torch under atmospheric or soft vacuum conditions. The investigations were directed in order to have an open micro porous structure, higher electrical conductivity and catalytic activity of anode deposits. Porosity was investigated by measuring the gas permeability. SEM and XRD technologies were applied to examine the morphology, microstructure and composition of the layers. Electrical conductivity measurements were carried out to determine ohmic losses within the anode layer. Most promising layers were analyzed by measuring the electrochemical behavior to obtain information about catalytic activity and performance.