X射线光电子能谱
原子层沉积
电极
材料科学
电化学
电解质
石英晶体微天平
阴极
锂(药物)
化学工程
涂层
氧化物
极化(电化学)
介电谱
分析化学(期刊)
纳米技术
薄膜
化学
冶金
工程类
内分泌学
物理化学
吸附
医学
有机化学
色谱法
作者
Gordon H. Waller,Philip Davis Brooke,Ben H. Rainwater,Steven Lai,Renzong Hu,Y. Ding,Faisal M. Alamgir,Ken H. Sandhage,Meilin Liu
标识
DOI:10.1016/j.jpowsour.2015.11.114
摘要
Aluminum oxide coatings deposited on LiMn2O4/carbon fiber electrodes by atomic layer deposition (ALD) are shown to enhance cathode performance in lithium-ion batteries. With a thin Al2O3 coating derived from 10 ALD cycles, the electrodes exhibit 2.5 times greater capacity retention over 500 cycles at a rate of 1C as well as enhanced rate capability and decreased polarization resistance. Structural and surface studies of the electrodes before and after cycling reveal that a near-surface phenomenon is responsible for the improved electrochemical performance. The crystal structure and overall morphology of the LiMn2O4 electrode are found to be unaffected by electrochemical cycling, both for coated and uncoated samples. However, evidence of Mn diffusion into the ALD coatings is observed from both transmission electron microscopy/energy-dispersive X-ray spectroscopy (TEM-EDS) and X-ray Photoelectron Spectroscopy (XPS) after electrochemical cycling. Furthermore, XPS analysis of the Al 2p photoemission peak for the ALD coated electrodes reveal a significant shift in binding energy and peak shape, suggesting the presence of an Al–O–F compound formed by sequestering HF in the electrolyte. These observations provide new insight toward understanding the mechanism in which ultrathin coatings of amphoteric oxides can inhibit capacity loss for LiMn2O4 cathodes in lithium-ion batteries.
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