GDC (Ce_(0.9)Gd_(0.1)O_(1.95))를 전해질 및 전극물질로 활용한 저온형 SOFC 단전지의 제작 및 성능 평가
Fabrication and Characterizations of an Unit Cell of Low-Temperature SOFC Utilizing GDC(Ce_(0.9)Gd_(0.1)O_(1.95))on Its Electrolyte and Electrode Materials
전해질 단전지출력 전극물질;
- 원문 URL
Intrinsic advantages of SOFC (solid oxide fuel cell) over other types of fuel cells are well known but high operating temperature has brought many practical problems including the reliability and degradation for long term usage. These problems can be overcome by lowering the operating temperature of SOFC below 700℃. For the fabrication and operation of low temperature SOFC, careful selection of materials and processing is critical. Ceria-based electrolyte was chosen for high ionic conductivity at low temperatures. The dense electrolyte (GDC. Ce_(0.9)Gd_(0.1)O_(1.95)) and the porous cathode (SSC. Sm_(0.5)Sr_(0.5)CoO_(3)) were made by screen printing on the anode pellet which was fabricated by dry pressing. The anode substrate containing 55vol% of Ni after reduction had 31% pore volume and its surface was free from defects. The electrolyte paste viscosity for screen printing was decreased with increasing contents of dispersant KD2. Electrolyte paste with 3 wt% dispersant showed the lowest viscosity and dense electrolyte was obtained by sintering at 1400℃ for 2 hours. Separation of the cathode/electrolyte interface during sintering was avoided by using the cathode functional layer, which was the mixture of electrolyte powder and cathode powder (SSC:GDC=30:70 wt%). The cell was tested for the performance under various operating conditions such as different gas flow rates, operating temperatures, and under the mixed gas supply. The maximum power density at 650℃ was 389mW/㎠ with H_(2) (50sccm) / air (100sccm) and 508mW/㎠ with H_(2) (50sccm) / O_(2) (100sccm) gas supplied at anode and cathode, respectively. When fuel gas was changed to CH_(4) at 650℃, the maximum powder density was 337mW/㎠ with air supply. In case of mixed gas operation, the peak power density was 273mW/㎠ with O_(2) (100sccm), CH_(4) (50sccm) and N_(2) (100sccm) gas mixture at 650℃. It was shown in this study that ceria-based, low temperature SOFC can be fabricated through careful control of defects on the surface of anode substrate, use of low viscosity electrolyte paste and functional interlayer between electrolyte and cathode. Low temperature down to 500℃ using fuel gases (H_(2) and CH_(4)) and oxidant gases (air and O_(2)) showed good power generating characteristics. In addition, mixed gas operation using CH_(4), O_(2) and N_(2) was possible suggesting the potential to miniaturization of SOFC operating at low temperatures.
- 이 논문과 함께 이용한 콘텐츠