Application of Flash Light Sintering Method to Fabrication of Ceramic Electrolyte Material for Solid Oxide Fuel Cells

Abstract

Rapid expansion and development of population and technology requires vast amount of energy for human race. Nowadays, most of the energy production and consumption is based on fossil fuels, which has limited amount and harmful effects on environments. To overcome these problems, renewable energy conversion system emerged as a substitution for the conventional energy generating system. Fuel Cells is the one of the energy conversion systems that has high energy efficiency and eco-friendly characteristics. Solid oxide fuel cells(SOFCs) is promising type of fuel cells due to the its great fuel conversion efficiency and environmental friendly emissions. However, SOFCs high operating temperature(800-1000℃) arouse many thermal problems. To overcome these problems, researchers have been motivated to lowering the operating temperature while maintaining the performance at low temperature region(400-600℃). The researches about low temperature SOFCs (LT-SOFCs) have been conducted to reduce the ohmic loss of SOFCs. The first method was reducing the thickness of the electrolyte by fabricating the electrolyte layer as thin-film. The other was changing the electrolyte material, which has high ionic conduction performance at low temperature range. However, the fabrication process of the thin-film went through the sintering step. This sintering step requires long process time(hours) and vast amount of energy. To overcome these problems, many researchers tried to substitute the conventional sintering method.

In this study, scandia-stabilized zirconia (ScSZ) electrolyte thin-film layers were deposited via chemical solution deposition (CSD). We selected 10ScSZ (10%Sc_2 O_3 ,90%ZrO_2 molar ratio) as the target material, and the precursor solution was prepared by precise calculations. The 10ScSZ solution was deposited on Al2O3 substrate using a spin-coating method. Then, the substrate was sintered using two methods: flash light irradiation and thermal. The characteristics of the thin films were compared, including ionic conductivity, surface morphology, and chemical composition. Pulsed light sintering was applied in the sintering step under a variety of energy density conditions from 80 J/cm^2to 130 J/cm^2, irradiation on/off times of 10 ms and 10 ms/500 ms, number of pulses, and bottom heat from 300℃ to 600℃. The ionic conductivity of the ScSZ electrolyte layers fabricated by thermal or flash light irradiation methods was tested and compared. The results show that the ScSZ electrolyte layer sintered by flash light irradiation within a few seconds of process time had similar ionic conductivity to the thermal-sintered electrolyte layer for about 10 hours including cooling process.