The Reaction Mechanism and Capacity Degradation Model in Lithium Insertion Organic Cathodes, Li2C6O6, Using Combined Experimental and First Principle Studies

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• 作者：Haegyeom Kim ; Dong-Hwa Seo ; Gabin Yoon ; William A. Goddard ; III ; Yun Sung Lee ; Won-Sub Yoon ; Kisuk Kang
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2014
• 出版时间：September 4, 2014
• 年：2014
• 卷：5
• 期：17
• 页码：3086-3092
• 全文大小：563K
• ISSN：1948-7185

文摘

Herein, we explore the capacity degradation of dilithium rhodizonate salt (Li₂C₆O₆) in lithium rechargeable batteries based on detailed investigations of the lithium de/insertion mechanism in Li₂C₆O₆ using both electrochemical and structural ex situ analyses combined with first-principles calculations. The experimental observations indicate that the Li_xC₆O₆ electrode undergoes multiple two-phase reactions in the composition range of 2 鈮?x 鈮?6; however, the transformations in the range 2 鈮?x 鈮?4 involve a major morphological change that eventually leads to particle exfoliation and the isolation of active material. Through first-principles analysis of Li_xC₆O₆ during de/lithiation, it was revealed that particle exfoliation is closely related to the crystal structural changes with lithium deinsertion from C₆O₆ interlayers of the Li_xC₆O₆. Among the lithium ions found at various sites, the extraction of lithium from C₆O₆ interlayers at 2 鈮?x 鈮?4 decreases the binding force between the C₆O₆ layers, promoting the exfoliation of C₆O₆ layers and pulverization at the electrode, which degrades capacity retention.

Keywords:

organic electrode; batteries; biomass; electrochemistry; first-principle calculation