期刊
JOURNAL OF PHYSICAL CHEMISTRY C
卷 120, 期 21, 页码 11372-11381出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.jpcc.6b02828
关键词
-
资金
- Austrian Federal Ministry of Science, Research and Economy
- National Foundation for Research, Technology and Development
- Deutsche Forschungsgemeinschaft [WI-3600 4-2]
One of the most widely known anode materials with excellent cycling performance in lithium-ion batteries is zero-strain lithium titanate Li4Ti5O12 (LTO). This is based on the highly reversible insertion and deinsertion of Li ions varying the composition of Li4+xTi5O12 from x = 0 to x = 3. The facile incorporation of Li is tightly connected with bulk Li ion dynamics. Although macroscopic electrochemical properties have been studied in great detail, bulk Li ion diffusion pathways have rarely been probed experimentally from an atomic scale point of view. Here, we evaluated 1D and 2D Li-6 magic angle spinning (MAS) NMR spectra recorded as a function of x to make the local magnetic changes during Li insertion-visible. This enabled us to directly show that rapid Li exchange involves the 8a and 16c sites, forming a 3D network throughout the LTO spinet structure. In contrast, considering the time scale set by our NMR experiments, the Li ions residing on the mixed occupied octahedral positions 16d are quite immobile. Under the MAS conditions applied, they definitely do not participate in rapid Li self-diffusion as evidenced by rather long site-specific longitudinal relaxation times as well as the absence of any NMR coalescence effects. Based on the NMR spectra, we propose a refined Li insertion mechanism which includes the initial formation of a highly conducting quasi solid solution characterized by rapid Li ion exchange.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据