Degradation phenomena in a solid oxide electrolysis cell after 9000 h of operation
Degradation phenomena in a solid oxide electrolysis cell after 9000 h of operation
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DOI：
10.1016/j.jpowsour.2012.09.061
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发表时间：
2013-02
影响因子：
9.2
通讯作者：
F. Tietz;D. Sebold;A. Brisse;J. Schefold
中科院分区：
文献类型：
--
作者：
F. Tietz;D. Sebold;A. Brisse;J. Schefold
阳极支撑型固体氧化物燃料电池（SOFC）作为固体氧化物电解槽电池（SOEC）以-1Acm-2的电流密度运行9000小时，显示出约40 mV kh-1的电压增加，即总电压劣化率为3.8%kh-1。该电池由氧化钇稳定的氧化锆（YSZ）与作为电解质的氧化钆取代的二氧化铈层组合组成。氢电极为Ni/YSZ金属陶瓷，氧电极为La0.58Sr0.4Co0.2Fe0.8O3钙钛矿（LSCF）。电解操作后，对电池进行金相分析，以确定降解过程。与初始状态相比，最明显的变化被发现在电解质层，这表明穿晶纵向孔隙率以及严重的孔形成沿着晶界。此外，观察到材料传输到氧化铈基扩散阻挡层中。氧电极在亚μm范围内表现出成分变化，并且在整个电极厚度上表现出不同程度的重结晶。微观结构观察与已经报道的阻抗谱结果一致，这表明（i）欧姆电解质电阻的增加作为主要的降解特征，这是SOEC操作所特有的，以及（ii）电极反应过电位的增加。
An anode-supported solid oxide fuel cell (SOFC) was operated for 9000 h as a solid oxide electrolyser cell (SOEC) with a current density of −1 Acm−2showing a voltage increase of about 40 mV kh−1, i.e. an overall voltage degradation rate of 3.8% kh−1. The cell consisted of yttria-stabilised zirconia (YSZ) combined with a gadolinia-substituted ceria layer as electrolyte. The hydrogen electrode was a Ni/YSZ cermet, and the oxygen electrode a La0.58Sr0.4Co0.2Fe0.8O3perovskite (LSCF). After electrolysis operation, the cell was metallographically analysed to identify degradation processes. Compared with the initial state, the most pronounced change was found at the electrolyte layer, which showed trans-granular longitudinal porosity as well as severe pore formation along grain boundaries. In addition, material transport was observed into the ceria-based diffusion barrier layer. The oxygen electrode showed compositional variations in the sub-μm range and different degrees of recrystallisation across the electrode thickness. The microstructural observations agree with the already reported impedance spectroscopic results, which indicated (i) an increase in ohmic electrolyte resistance as the dominant degradation feature, which is specific to SOEC operation, and (ii) an increase in the electrode reaction overpotentials.