期刊
APPLIED SURFACE SCIENCE
卷 563, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.apsusc.2021.150334
关键词
Li-ion battery; Li1.2Ni0.2Mn0.6O2; Density functional theory; Surface oxygen release; Anionic redox; Electronic structures
类别
资金
- Ministry of Science and Technology, Taiwan [MOST 108-2923-E-011-002, MOST 109-2639-E-011-001-ASP]
The study systematically explores the oxygen oxidation mechanisms on the Li1.2Ni0.2Mn0.6O2 surface and identifies the triggering factors and oxidation pathways for oxygen dimerization. Suppressing the release of oxygen molecules can be achieved by modifying the surface's oxygen coordination environment.
Li-rich layered manganese oxide-based cathodes have drawn much attention for the next-generation lithium-ion batteries due to the large discharge capacities and low cost. However, the lattice oxygen release and subsequent surface densification during cycling inevitably lead to their instability, which incurs capacity failure at high voltage. Herein, we have systematically explored the oxygen oxidation mechanisms in Li1.2Ni0.2Mn0.6O2 (003) surface by considering five possible different local oxygen coordination environments and investigate their oxidation process during the different degrees of delithiation. Based on the density functional theory calculations, we identify the triggering factors for the oxygen dimerization at the cathode surface. Our study reveals that the oxygen atoms linearly coordinated with two Li-ions (Li-O-Li geometries) are unstable and proceed oxidation via O2- to O- to O-2(2-) to O-2(-) and finally O-2 evolution occurred on the cathode surface at a higher degree of delithiation. Based on our theoretical results, we expect that the oxygen molecule release can be suppressed by modifying the surface's oxygen coordination environment. Such a comprehensive understanding is essential for developing the novel complex Li-rich layered manganese oxide cathodes.
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