Department of Chemical and Environmental Engineering, Yale University , 9 Hillhouse Avenue, New Haven, Connecticut 06511, United States.
Department of Chemical and Biological Engineering, Sookmyung Women's University , 100 Cheongpa-ro 47-gil, Yongsan-gu, Seoul, 04310, Republic of Korea.
Nano Lett. 2016 Aug 10;16(8):4799-806. doi: 10.1021/acs.nanolett.6b00856. Epub 2016 Jul 5.
Understanding the catalyzed formation and evolution of lithium-oxide products in Li-O2 batteries is central to the development of next-generation energy storage technology. Catalytic sites, while effective in lowering reaction barriers, often become deactivated when placed on the surface of an oxygen electrode due to passivation by solid products. Here we investigate a mechanism for alleviating catalyst deactivation by dispersing Pd catalytic sites away from the oxygen electrode surface in a well-structured anodic aluminum oxide (AAO) porous membrane interlayer. We observe the cross-sectional product growth and evolution in Li-O2 cells by characterizing products that grow from the electrode surface. Morphological and structural details of the products in both catalyzed and uncatalyzed cells are investigated independently from the influence of the oxygen electrode. We find that the geometric decoration of catalysts far from the conductive electrode surface significantly improves the reaction reversibility by chemically facilitating the oxidation reaction through local coordination with PdO surfaces. The influence of the catalyst position on product composition is further verified by ex situ X-ray photoelectron spectroscopy and Raman spectroscopy in addition to morphological studies.
理解锂-氧化物产物在锂-氧电池中的催化形成和演化对于开发下一代储能技术至关重要。催化位点在降低反应势垒方面非常有效，但由于固体产物的钝化作用，当放置在氧电极表面时，往往会失活。在这里，我们研究了一种通过在结构良好的阳极氧化铝（AAO）多孔膜夹层中将 Pd 催化位点分散在远离氧电极表面的位置来缓解催化剂失活的机制。我们通过对从电极表面生长的产物进行表征，观察了 Li-O2 电池中横截面产物的生长和演化。我们独立于氧电极的影响，研究了催化和非催化电池中产物的形态和结构细节。我们发现，通过与 PdO 表面的局部配位，通过化学方式促进氧化反应，催化剂在远离导电电极表面的几何装饰显著提高了反应的可逆性。通过外加 X 射线光电子能谱和拉曼光谱以及形态研究进一步验证了催化剂位置对产物组成的影响。
