Coating internal surface of porous electrode for decreasing the ohmic resistance and shifting oxygen reduction reaction pathways in solid oxide fuel cells
Coating internal surface of porous electrode for decreasing the ohmic resistance and shifting oxygen reduction reaction pathways in solid oxide fuel cells
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DOI：
10.1016/j.jpowsour.2021.229854
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发表时间：
2021-04-24
影响因子：
9.2
通讯作者：
Song, Xueyan
中科院分区：
文献类型：
--
作者：
Chen, Yun;Paredes-Navia, Sergio A.;Song, Xueyan
对于固体氧化物燃料电池(SOFC)中的混合导体La0.6Sr0.4Co0.2Fe0.803-x(LSCF)，离子表面偏析，如挥发的锶，从而失去氧还原反应(ORR)的导电性和活性中心。为了减轻阳离子偏析，一种实用的方法是应用保形表面涂层。然而，涂层将不可避免地改变最初发生在主干表面的ORR路径。本研究将铂或钴的一元电催化剂应用于固体氧化物燃料电池的LSCF/Sm掺杂CeO2(SDC)复合电极。这两层ALD涂层都与复合阴极形成了强烈的相互作用。在运行过程中，铂涂层在LSCF颗粒表面保持共形，但在SDC表面转变为离散颗粒。对于CoOx涂层，LSCF和SDC上的共形层均为分散的纳米晶。仅阴极的ALD涂层就降低了电池的欧姆电阻。ALD诱导的电导率变化可归因于不同的机制。这项研究提出了一种新的可行的方法，在混合导体的表面涂覆一层共形致密的涂层，同时提高SOFC阴极的导电性和耐久性。
For mixed conductor La0.6Sr0.4Co0.2Fe0.8O3-x (LSCF) in solid oxide fuel cells (SOFCs), cation surface segregation such as volatile Sr and consequently losing conductivity and active sites for the oxygen reduction reaction (ORR) are problematic. To mitigate the cation segregation, a practical approach is to apply a conformal surface coating. Nevertheless, the coating layer would inevitably alter the ORR pathways that initially take place on the backbone surface. In this study, the unary electrocatalyst of Pt or CoOx was applied to the LSCF/Sm-doped CeO2 (SDC) composite electrode of inherently functional SOFCs. Both ALD coating layers evolve strong interaction with the composite cathode. Upon operations, the Pt coating layer remains conformal on LSCF grain surfaces but turns into discrete particles on SDC. For the CoOx coating, the conformal layer grows to be the discrete nano-grains on both the LSCF and SDC grains. ALD coating of the cathode alone reduces the cell ohmic resistance. The ALDinduced conductivity change is ascribed to different mechanisms. This study presents a novel and feasible approach to apply a conformal, dense coating layer on the surface of a mixed conductor, simultaneously increasing the conductivity and durability of the SOFC cathode.