Understanding the Influence of Composition and Synthesis Temperature on Oxygen Loss, Reversible Capacity, and Electrochemical Behavior of xLi2MnO3-(1 鈥?x)LiCoO

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• 作者：Xingde Xiang ; James C. Knight ; Weishan Li ; Arumugam Manthiram
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：October 16, 2014
• 年：2014
• 卷：118
• 期：41
• 页码：23553-23558
• 全文大小：454K
• ISSN：1932-7455

文摘

With an aim to broaden the understanding of the role of Co³⁺ in the lithium-rich layered oxide cathodes for lithium-ion batteries, the influence of composition and synthesis temperature on the oxygen loss, reversible capacity, and electrochemical behavior of the xLi₂MnO₃-(1 鈥?x)LiCoO₂ series in the first cycle has been systematically investigated. The charge capacity first increases with increasing x value from 0.2 to 0.6 due to the enhanced oxygen loss, but then decreases with further increase in x from 0.6 to 0.8. Although the discharge capacity shows a trend similar to the charge capacity, the maximum value appears at x = 0.4鈥?.5, rather than at x = 0.6 because of its larger irreversible capacity loss. Surprisingly, raising the synthesis temperature from 800 to 1000 掳C alters the electrochemical behavior of the first charge. The materials synthesized at 900 and 1000 掳C show a three-step reaction process consisting of the oxidation of Co³⁺, simultaneous oxidation of Co³⁺ and O^{2鈥?/sup>, and finally the oxidation of O2鈥?/sup> only, while those synthesized at 800 掳C exhibit a two-step reaction process composed of Co3+ oxidation and O2鈥?/sup> oxidation occurring separately.}