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Unravelling Solid-State Redox Chemistry in Li

在李揭开固态氧化还原化学

【作       者】:

Wang Hay Kan,Dongchang Chen,...

【机       构】: 美国国家标准与技术研究院
【承研机构】:

【原文地址】: https://www.nist.gov/publications/unravelling-solid-state-redox-chemistry-li13nb03mn04o2-single-crystal-cathode-material
【发表时间】:

2018-03-13

摘要

Recent reports on high capacities delivered by Li-excess transition-metal oxide cathodes have triggered intense interest in utilizing reversible oxygen redox for high-energy battery applications. In order to control oxygen electrochemical activities, fundamental understanding of redox chemistry is essential, yet so far proven challenging. In the present study, micron-sized LiNbMnd2^ single crystals were synthesized for the first time and used as a platform to understand the charge compensation mechanism during Li extraction and insertion. We explicitly demonstrate that the oxidation of Oto O(02 loss from the lattice dominates at 4.5 V and 4.7 V, respectively. While both processes occur in the first cycle, only the redox of O/Oparticipates in the following cycles. The lattice anion redox process triggers irreversible changes in Mn redox, which likely causes the voltage and capacity fade observed on this oxide. Two drastically different redox activity regions, a single-phase behavior involving only Mnand a two-phase behavior involving Oun- (0{less than or equal}n 2), were found in LiNbMnO(0

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