成果報告書詳細
管理番号20150000000151
タイトル*平成26年度中間年報 固体酸化物形燃料電池等実用化推進技術開発 次世代技術開発 可逆動作可能な固体酸化物型燃料電池による低コスト水素製造および高効率発電を利用した電力貯蔵
公開日2016/12/9
報告書年度2014 - 2014
委託先名国立大学法人九州大学
プロジェクト番号P13001
部署名新エネルギー部
和文要約
英文要約In the last year, it was found that fuel electrode activity in both electrolysis and fuel cell mode was much increased by mixing Sm doped CeO2 with NiFe bimetal. In this year, stability of this NiFe-SDC fuel electrode under reversible operation was studied. At 100mA/cm2, terminal potential of 1.025 and 1.125 V were observed for power generation and steam electrolysis, respectively, and so energy efficiency was around 91% in this cell. During 30 cycles, the stable terminal potential was observed, however, terminal potential was slightly decreased after 50 cycles, and the maximum power density was decreased from 0.6 to 0.45 W/cm2 at 800℃. Detail analysis of internal resistance suggests that decrease in power density could be explained by increased IR loss and overpotential of fuel electrode. XRD analysis suggests that oxidation of NiFe in fuel electrode occurred after 50 cycles and so for further increasing stability, preventing the oxidation of NiFe is required. For this purpose, we applied oxide for fuel electrode and it was found that CMF which is active for anode in SOFC mode is also active for steam electrolysis and so CMF is one of the promising materials for fuel elctrode.
Application of thin film LSGM electrolyte for low temperature steam electrolysis was also studied. Electrolysis current can be much increased by using LSGM thin film electrolyte which was prepared by screen print method and at 500℃, electrolysis current of 120 mA/cm2 was achieved at 1.3V. IR loss is dominated the internal resistance and so it is expected that further larger current density could be expected by decreasing IR loss at interface of electrolyte and substrate.
For decreasing internal resistance, tubular type SORC was prepared by using dip coating method. In this year, by inserting CMF for buffer layer, it was found that Ni diffusion can be suppressed drastically and the prepared cell shows OCV higher than 1.1V which is close to theoretical value and power density even at 500℃ was 0.29, 0.18, 0.10 W/cm2 at 700, 600, 500℃, respectively. The observed power density was almost achieved the aimed value. Since large IR loss, in particular, IR loss at cathode side was still observed. Therefore, by optimizing the cathodic preparation method, further larger power density was expected.
For achieving high charge rate at lower temperature, reduction performance of Fe2O3 was also studied. Since CMF is effective for increasing oxidation rate of Fe, effect of CMF catalyst on Fe2O3 reduction was studied. However, it was found that reduction of Fe2O3 is reasonably fast and can be reduced to metallic state up to 400℃. Reduction rate was independent of CMF mixing, however, mixing CMF is effective for preventing aggregation of Fe resulting in much increased stability for redox cycle. In next year, mixing state of CMF on Fe2O3 will be studied in details.
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