通过旋转环盘和光谱测量深入了解 Na-O 电池中 NaO 的电化学氧化。
Insights into Electrochemical Oxidation of NaO in Na-O Batteries via Rotating Ring Disk and Spectroscopic Measurements.
机构信息
Research Laboratory of Electronics, ‡Electrochemical Energy Laboratory, §Department of Mechanical Engineering, ∥Department of Chemistry, and ⊥Department of Materials Science & Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
出版信息
ACS Appl Mater Interfaces. 2017 Feb 8;9(5):4374-4381. doi: 10.1021/acsami.6b08355. Epub 2016 Nov 18.
O reduction in aprotic Na-O batteries results in the formation of NaO, which can be oxidized at small overpotentials (<200 mV) on charge. In this study, we investigated the NaO oxidation mechanism using rotating ring disk electrode (RRDE) measurements of Na-O reaction products and by tracking the morphological evolution of the NaO discharge product at different states of charge using scanning electron microscopy (SEM). The results show that negligible soluble species are formed during NaO oxidation, and that the oxidation occurs predominantly via charge transfer at the interface between NaO and carbon electrode fibers rather than uniformly from all NaO surfaces. X-ray absorption near edge structure (XANES), and X-ray photoelectron spectroscopy (XPS) measurements show that the band gap of NaO is smaller than that of LiO formed in Li-O batteries, in which charging overpotentials are much higher (∼1000 mV). These results emphasize the importance of discharge product electronic structure for rationalizing metal-air battery mechanisms and performance.
无质子 Na-O 电池的还原会导致 NaO 的形成，NaO 在充电时可以在较小的过电势（<200 mV）下被氧化。在这项研究中，我们使用旋转环盘电极（RRDE）测量 Na-O 反应产物，并通过扫描电子显微镜（SEM）跟踪 NaO 放电产物在不同荷电状态下的形态演变，来研究 NaO 的氧化机制。结果表明，在 NaO 氧化过程中几乎没有形成可溶性物质，并且氧化主要通过 NaO 与碳纤维电极之间的界面上的电荷转移发生，而不是从所有 NaO 表面均匀发生。X 射线吸收近边结构（XANES）和 X 射线光电子能谱（XPS）测量表明，NaO 的带隙小于在 Li-O 电池中形成的 LiO 的带隙，Li-O 电池的充电过电势要高得多（约 1000 mV）。这些结果强调了放电产物电子结构对于合理化金属空气电池机制和性能的重要性。
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