Interactions of Dimethoxy Ethane with Li2O2 Clusters and Likely Decomposition Mechanisms for Li鈥揙2 Batteries

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• 作者：Rajeev S. Assary ; Kah Chun Lau ; Khalil Amine ; Yang-Kook Sun ; Larry A. Curtiss
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：April 25, 2013
• 年：2013
• 卷：117
• 期：16
• 页码：8041-8049
• 全文大小：533K
• 年卷期：v.117,no.16(April 25, 2013)
• ISSN：1932-7455

文摘

One of the major problems facing the successful development of Li鈥揙₂ batteries is the decomposition of nonaqueous electrolytes, where the decomposition can be chemical or electrochemical during discharge or charge. In this paper, the decomposition pathways of dimethoxy ethane (DME) by the chemical reaction with the major discharge product, Li₂O₂, are investigated using theoretical methods. The computations were carried out using small Li₂O₂ clusters as models for potential sites on Li₂O₂ surfaces. Both hydrogen and proton abstraction mechanisms were considered. The computations suggest that the most favorable decomposition of ether solvents occurs on certain sites on the lithium peroxide surfaces involving hydrogen abstraction followed by reaction with oxygen, which leads to oxidized species such as aldehydes and carboxylates as well as LiOH on the surface of the lithium peroxide. The most favorable site is a Li鈥揙鈥揕i site that may be present on small nanoparticles or as a defect site on a surface. The decomposition route initiated by the proton abstraction from the secondary position of DME by the singlet cluster (O鈥揙 site) requires a much larger enthalpy of activation, and subsequent reactions may require the presence of oxygen or superoxide. Thus, pathways involving proton abstraction are less likely than that involving hydrogen abstraction. This type of electrolyte decomposition (electrolyte with hydrogen atoms) may influence the cell performance including the crystal growth, nanomorphologies of the discharge products, and charge overpotential.