Theoretical understanding of stability of the oxygen electrode in a proton-conductor based solid oxide electrolysis cell
Theoretical understanding of stability of the oxygen electrode in a proton-conductor based solid oxide electrolysis cell
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DOI：
10.1016/j.ijhydene.2023.04.148
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发表时间：
2023-05
影响因子：
7.2
通讯作者：
Yudong Wang;Barbara Marchetti;Xiaoping Zhou
中科院分区：
文献类型：
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作者：
Yudong Wang;Barbara Marchetti;Xiaoping Zhou
基于质子导体的固体氧化物电池中的氧电极通常是一种三重导电材料，能够传输和交换电子（e−），氧离子（o2−）和质子（H+），从而扩大活性区域以提高氧电极的活性。本文建立了一个理论模型，通过研究中性物质（即μ o2、μ h2和μ h2o）的化学势随输运性质、操作参数和电池几何形状的函数来理解三导氧电极的稳定性。我们的理论认识表明：(1)：在传统的氧离子基固体氧化物电池中，在电解模式下，氧电极中存在高μ O 2（即高氧分压），这可能导致电极/电解质界面形成裂纹。而在基于质子导体的固体氧化物电池中，μ O的含量显著降低，抑制了裂纹的形成，从而提高了性能稳定性(2)。在典型的基于质子导体的固体氧化物电解槽中，μ o2对法拉第效率的依赖可以忽略不计。因此，阻断电子电流的方法可以在实现稳定性的同时提高电解效率(3)。通过使用高离子导电性组分和改善电极动力学，可以减小氧电极与气相之间的μ O 2（即p O 2）差，从而进一步提高电极的稳定性。
The oxygen electrode in a proton-conductor based solid oxide cells is often a triple-conducting material that enables the transport and exchange of electrons (e−), oxygen ions (O 2−), and protons (H+), thus expanding active areas to enhance the oxygen electrode activity. In this work, a theoretical model was developed to understand stability of tri-conducting oxygen electrode by studying chemical potentials of neutral species (ie, μ O 2, μ H 2, and μ H 2 O) as functions of transport properties, operating parameters, and cell geometry. Our theoretical understanding shows that (1): In a conventional oxygen-ion based solid oxide cell, a high μ O 2 (thus high oxygen partial pressure) exists in the oxygen electrode during the electrolysis mode, which may lead to the formation of cracks at the electrode/electrolyte interface. While in a proton-conductor based solid oxide cell, the μ O 2 is reduced significantly, suppressing the crack formation, and resulting in improved performance stability (2). In a typical proton-conductor based solid oxide electrolyzer, the dependence of μ O 2 on the Faradaic efficiency is negligible. Hence, approaches to block the electronic current can improve the electrolysis efficiency while achieving stability (3). The difference of the μ O 2 (thus p O 2) between the oxygen electrode and gas phase can be reduced by using higher ionic conducting components and improving electrode kinetics, which lead to further improvement of electrode stability.