成果報告書詳細
管理番号20110000000951
タイトル*平成22年度中間年報 固体酸化物形燃料電池システム要素技術開発/耐久性・信頼性向上に関する基礎研究/高温円筒横縞型耐久性の評価と不純物に対する影響評価
公開日2011/12/13
報告書年度2010 - 2010
委託先名三菱重工業株式会社
プロジェクト番号P08004
部署名新エネルギー部
和文要約和文要約等以下本編抜粋:1. 概要
(1)研究概要
【中間評価まで】
「信頼性向上プロジェクト」で抽出された課題を改善するため、高温円筒横縞形スタックの発電試験条件が物質の拡散状態ならびに三相界面近傍の組織変化に及ぼす影響を解析すると共に、性能劣化との相関を比較分析することで劣化現象の把握と劣化機構の解明を行う。また空気中に含まれる微量不純物が、耐久性に及ぼす影響を評価するとともに、試験後に解体調査し、劣化現象の把握と劣化機構の解明を行うことで技術課題を抽出する。試験後の解体分析および微量不純物の影響については、大学および研究機関と連携して進める。
【中間評価後】
劣化要因に対する改善を施したセルスタックにて、5000 時間程度の耐久性試験を行い、目標とする耐久性40,000 時間(電圧低下率 0.25%/1000h)への見通しを得る。また起動停止試験もセルスタックにて実施し、起動停止回数250 回の見通しを得る。更に微量不純物については、抽出された技術課題を基に電池材料に及ぼす影響を評価する。
英文要約Abstract
In order to understand and clarify degradation phenomena and mechanism of segmented-in-series tubular type cell stack used at high temperature, we analyzed correlations of performance degradation and microstructure change or material
inter-diffusion at three phase boundary region depending on change of power generation test condition in this project.
Since a metal tube for air supply / discharge was installed in the generator room at high temperature, it was presumed
that Cr poisoning was one of the causes of degradation. For this reason, the metal tube was changed into a ceramic pipe and the durability test was carried out. Furthermore, examinations for predicting durability of module, i.e., temperature
distribution, high utilizations of fuel and air, influence of air containing impurities, were also executed. The influence of
thermal insulation was investigated as impurities of air supplied to a cell stack in the module. The cell stacks after the
durability tests were analyzed with universities and research institutions and technical issues were extracted to improve the durability.
Degradation rate of mean voltage applying the LSM-YSZ cathode interlayer decreased from 0.83 to 0.76%/1000 h by the measure against Cr poisoning using the ceramic tube. Then the amount of chromium deposition at the
cathode/electrolyte interface vicinity decreased from hundreds of ppm to several ppm. In order to suppress interdiffusion at interface vicinity of cathode/LSM-YSZ interlayer/electrolyte, cathode interlayer changed into SDC, since the
interdiffusion of composition element contained in the layers was observed. The mean voltage of cell stack applying the SDC interlayer started the deterioration after about 2700 hours, and degradation rate of 2700 to 6000 hours
decreased to 0.13%/1000 h at the test of homogeneous temperature at 900℃. A cell stack increasing the density of
interconnect part overlapping electrolyte with SDC interlayer was fabricated and the durability test was conducted at
900℃. Then the deterioration of improved cell stack was not observed in the durability test of 5000 h.
Tendency which the degradation rate of cells at 800℃ or less increases was observed in the temperature distribution
test. Degradation rate of the durability test attaching thermal insulations around a cell stack increased equally, but
the high-utilizations of fuel and oxidant did not much influence the degradation.
As a result of analyzing the cell stacks with SDC interlayer after the durability tests, dense layer was observed at the
interface of LSCM/SDC and the density of SDC interlayer increased, but no degradation was observed at
900℃. Further, pores were formed at the interface of LSCM/SDC and SDC layer. Elemental distribution maps of cross
sections showed that Sm and Mn diffused and the micro structure changed. The tendency for the dense layer of an
interface to become thick was observed with lowering the temperature. This phenomenon was presumed that the
diffusion velocity of Mn in LSCM has influenced.
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