Strain Accumulation Study of Ni-based Anode-Supported Solid Oxide Fuel Cells under Partial-Redox Cycling Conditions
Strain Accumulation Study of Ni-based Anode-Supported Solid Oxide Fuel Cells under Partial-Redox Cycling Conditions
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部分氧化还原循环条件下镍基阳极支撑固体氧化物燃料电池的应变累积研究
DOI：
10.20964/2016.07.28
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发表时间：
2016-07
影响因子：
1.5
通讯作者：
Zhao Xiang
中科院分区：
文献类型：
--
作者：
Lou Kang;Wang Fenghui;Lu Yongjun;Zhao Xiang
当循环次数较高（~10）时，即使氧化程度低于临界水平（~50%），部分氧化还原循环也会导致镍基阳极支撑固体氧化物燃料电池（SOFC）严重退化（电解质裂纹）。在 SOFC 中实施时间控制的部分氧化还原循环，以研究应变积累的影响。研究发现，这种阳极部分氧化（10%-40%）然后完全还原的“部分氧化还原”循环可能会带来不可逆的电池膨胀和机械损伤，尽管在最初的几个循环中几乎没有出现任何裂纹。对于那些设计能经历数十甚至数百个氧化还原循环的NASC，这种现象需要更严格的再氧化水平限制。当阳极再氧化程度达到约20%时，观察到应变累积效应，低于该值电池是“安全的”。 NiO 和孔隙率梯度均沿阳极厚度出现。 SEM 研究表明，尽管再氧化程度恒定，但随着氧化还原循环次数的增加，氧化还原前沿向电解质移动。而化学反应被认为是氧化还原前沿移动的驱动力，不断给阳极带来不可逆的应变。
Partial-redox cycles lead to severe degradation (electrolyte cracks) to Ni-based anode-supported solid oxide fuel cell (SOFC) when the cycle number is high (~10), even though the oxidation degree is below the critical level (~50%). Time controlled partial-redox cycles were implemented in SOFCs to investigate the effect of strain accumulation. It is found that this “partial-redox” cycle in which anode was oxidized partially (10%-40%) and then fully reduced, may bring irreversible cell expansion and mechanical damage, although it showed hardly any crack in the first few cycles. This phenomenon requires a more rigid re-oxidation level of restriction for those NASCs designed living through dozens or even hundreds of redox cycles. Strain accumulation effect was observed when the anode reoxidation degree reached ca.20%, below which the cell was "safe". Both NiO and porosity gradient along anode thickness arise. SEM studies reveal that the redox front moves towards the electrolyte as redox cycle number increases, although the re-oxidation degree is constant. And the chemical reactions are considered the driving force for redox front move, which constantly bring irreversible strain to the anode.