Investigation of Fluorinated Amides for Solid鈥揈lectrolyte Interphase Stabilization in Li鈥揙2 Batteries Using Amide-Based Electrolytes

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• 作者：Vyacheslav S. Bryantsev ; Vincent Giordani ; Wesley Walker ; Jasim Uddin ; Ilkeun Lee ; Adri C. T. van Duin ; Gregory V. Chase ; Dan Addison
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：June 13, 2013
• 年：2013
• 卷：117
• 期：23
• 页码：11977-11988
• 全文大小：632K
• 年卷期：v.117,no.23(June 13, 2013)
• ISSN：1932-7455

文摘

Solvent and electrode stability is critical for the successful development of the rechargeable, organic electrolyte Li鈥揙₂ (air) battery. Straight-chain alkyl amides, such as N,N-dimethylacetamide (DMA), show superior stability at the O₂ cathode compared to organic carbonates and glymes, but these solvents do not form a stable solid鈥揺lectrolyte interphase (SEI) to prevent a sustained reaction with Li metal. In this work, we use electrochemical impedance spectroscopy and cycling tests on a symmetric Li/electrolyte/Li cell to determine the ability of several fluorinated amide solvents to stabilize the lithium/electrolyte interface. The LiTFSI/N,N-dimethyltrifluoroacetamide (DMTFA) system shows the smallest interfacial impedance and the lowest polarization for Li dissolution and deposition. We present quantum chemical calculations indicating that 伪-fluorinated alkyl amides are reduced on Li to form insoluble LiF with no or little activation energy. XPS analysis confirms the presence of LiF in the SEI on Li metal exposed to DMTFA, which is likely to play an important role in stabilizing the lithium/electrolyte interface. The improved stability of a metallic Li anode in a rechargeable Li鈥揙₂ battery with LiTFSI/DMA electrolyte is demonstrated using 2% DMTFA as the SEI-stabilizing additive.