Effect of pre-sintering of raw material powder on properties of solid oxide fuel cell electrolyte prepared by dip-coating method

Abstract

In order to remedy defects of thin electrolyte films, which significantly affect the power generation performance of solid oxide fuel cells (SOFCs), the effects of pre-sintering of raw material powder (8 mol % Y₂O₃-stabilized ZrO₂: YSZ) on the properties of the electrolyte were investigated. After pre-sintering YSZ powder under various temperature and time conditions, electrolytes (about 30 µm in thickness) were deposited on the substrates of fuel electrodes by a dip-coating method and then co-sintered. The microstructures of the electrolytes were observed by scanning electron microscopy and laser scanning confocal microscopy. The power generation performance of fabricated cells was also investigated. As a result, the electrolyte fabricated by pre-sintering YSZ powder at 200°C for 120 h was found to be dense and impermeable. The cell containing the electrolyte showed reasonable power generation performance. In the case where the pre-sintering temperature was maintained at 200°C and the pre-sintering time was shortened to 20 h, the electrolyte was found to be porous, and the open circuit voltage of the cell was lower than the theoretical value. By increasing the pre-sintering temperature to 600°C for 20 h, an ideal electrolyte could be obtained. In contrast, the electrolyte fabricated using the YSZ powder without pre-sintering was highly porous, leading to a considerable drop in open circuit voltage.