Coupling between oxygen redox and cation migration explains unusual electrochemistry in lithium-rich layered oxides

Title
Coupling between oxygen redox and cation migration explains unusual electrochemistry in lithium-rich layered oxides
Authors
홍지현William E. Gent임기필Yufeng LiangQinghao LiTaylor Barnes안성진Kevin H. StoneMitchell McIntireJay Hyok SongYiyang LiApurva MehtaStefano ErmonTolek TyliszczakDavid KilcoyneDavid Vine박진환두석광Michael F. ToneyWanli YangDavid PrendergastWilliam C. Chueh
Issue Date
2017-12
Publisher
Nature Communications
Citation
VOL 8, 2091
Abstract
Lithium-rich layered transition metal oxide positive electrodes offer access to anion redox at high potentials, thereby promising high energy densities for lithium-ion batteries. However, anion redox is also associated with several unfavorable electrochemical properties, such as open-circuit voltage hysteresis. Here we reveal that in Li1.17-xNi0.21Co0.08Mn0.54O2, these properties arise from a strong coupling between anion redox and cation migration. We combine various X-ray spectroscopic, microscopic, and structural probes to show that partially reversible transition metal migration decreases the potential of the bulk oxygen redox couple by > 1 V, leading to a reordering in the anionic and cationic redox potentials during cycling. First principles calculations show that this is due to the drastic change in the local oxygen coordination environments associated with the transition metal migration. We propose that this mechanism is involved in stabilizing the oxygen redox couple, which we observe spectroscopically to persist for 500 charge/discharge cycles.
URI
http://pubs.kist.re.kr/handle/201004/72493
ISSN
2041-1723
Appears in Collections:
KIST Publication > Article
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