Abstract
In the present study, a calcium- and nickel-doped yttrium chromates (YCCN)-based, conductive–protective layers for metallic interconnects used in the intermediate-temperature solid oxide fuel cells (IT-SOFCs) were investigated. Synthesis of Y0.8Ca0.2Cr1−xNixO3 (x = 0; 0.15 and 0.3) powders was performed using a wet chemistry method with two different complexing agents: ethylenediaminetetraacetic acid and glycine. Based on the result of thermal analysis of obtained precursors, optimal conditions of the calcination process were determined. Powders were then milled, compacted and sintered at different temperatures using free sintering method, into series of dense, polycrystalline sinters. The use of glycine precursor allowed obtaining a single-phase material in all cases. Based on the electrical and sintering properties, the Y0.8Ca0.2Cr0.85Ni0.15O3 material was selected for further studies. It was deposited using cost-effective screen-printing method on the Crofer 22APU ferritic stainless steel. To investigate properties and suitability of the resulting layer/steel system for IT-SOFCs applications, the high-temperature, dual-atmosphere studies were carried out for the first time for ceramic/metallic system, in conditions as close as possible to actual working conditions of the fuel cell. The layer exhibited high stability and good protective properties. The area-specific resistance of the studied ceramic layer/metallic substrate composite was determined, with the obtained value of 0.0366 Ω cm2 being within the arbitrary limit set for these materials (0.1 Ω cm2). The results show that the investigated materials are suitable for the projected application.
Highlights
In the era of growing demand of worldwide energy, the solid oxide fuel cells (SOFCs) are considered to be highly promising devices that might become efficient sources of electrical energy and heat in the future
The reduction of SOFC operating temperatures to the 600-800 °C range made it possible to employ cost-effective metallic interconnects such as ferritic stainless steel (FSS) (Ref 3), which are currently intensively studied as potential interconnect materials for IT-SOFCs due to their low cost, ease of production and favorable mechanical properties
Their main task is to improve the electrical properties of the interconnects over the time of fuel cell action by both reducing the oxidation rate of the metallic base and increasing the electrical conductivity of the metal/ceramic system
Summary
In the era of growing demand of worldwide energy, the solid oxide fuel cells (SOFCs) are considered to be highly promising devices that might become efficient sources of electrical energy and heat in the future Their main advantages are very high energy conversion efficiency and relatively low emissivity, which makes them very attractive for countries characterized by highly industrialized economy, such as Japan, Germany or Scandinavian countries. In order to limit the influence of this phenomenon, ceramic-based conductive–protective layers are used (Ref 4) Their main task is to improve the electrical properties of the interconnects over the time of fuel cell action by both reducing the oxidation rate of the metallic base and increasing the electrical conductivity of the metal/ceramic system. Calcium yttrium chromate (Y0.8Ca0.2CrO3; called YCC) and calcium–nickel-doped
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