Studies of Li Anodes in the Electrolyte System 2Me ‐  THF  /  THF  / Me ‐ Furan / LiAsF6

Abstract

The correlation between Li cycling efficiency, Li morphology, Li surface chemistry, and the properties of the Li-solution interphase was investigated in the THE 2Me-THE 2Me-Furan (MF), LiAsF6 electrolyte system. Surface sensitive FTIR, EDAX-x-ray mieroanalysis, SEM, and impedance spectroscopy were used in conjunction with standard electrochemical techniques. Using THF as a cosolvent to 2Me-THF decreases the detrimental impact of contaminants such as water as it is more reactive toward lithium than 2Me-THE The presence of MF (a few percent) influences the Li surface chemistry since its reduction to surface compounds with alkoxy groups suppresses solvent and salt reduction. However, its effect on Li morphology and cycling efficiency is marginal. It is concluded that the main positive impact of this additive reported in the literature is due to the stabilizing effect of the ethers by its possible reaction with trace Lewis acid contaminants in the solutions. The superiority of LiAsF6 as an eleetroiyte for these solutions is attributed to the precipitation of elementary arsenic and arsenic compounds (e.g., LisAs, LixAsFy) on lithium, which modifies Li deposition to become uniform and smooth.

Lithium Metal Anodes with Nonaqueous Electrolytes

“…Aurbach et al systematically investigated the composition and structure of SEI layers formed in various electrolytes using different techniques, including spectroscopy (e.g., Fourier-transform infrared spectroscopy [FTIR], X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, X-ray diffraction [XRD], and Raman spectroscopy) and microscopy (SEM, atomic force microscopy, and scanning tunneling microscopy). ,,,− They identified the morphology (crystalline or amorphous) and composition of SEI layers formed on graphite anode by in situ XRD and FTIR . In general, the surface films developed at low potential had a similar composition to those developed on Li.…”

Current status and future perspectives of lithium metal batteries

“…These reactive monomers form an electrochemically stable and organic rich polymer layer, upon electrochemical reduction at ~0.9 V vs Li/Li + . This group of additives contains, amongst others, vinylene carbonate (VC) [42,43], fluoroethylene carbonate (FEC) [44], vinylene ethylene carbonate [45,46], methyl cinnamate [47], vinyl-containing silane-based compounds [48], and furan derivates [49]. The polymerization of vinylene carbonate (VC) occurs at the carbon-carbon double bond (C--C).…”

From molecular models to system analysis for lithium battery electrolytes

“…One can note that propylene oxide units used to prevent crystallinity, to provide cross-linkable points or to form comb structures are more susceptible to oxidation or acid catalyzed reactions. Chain scission is expected at the anode [59,60] which may result in a weakening of the mechanical properties of the electrolyte and consequent growth of dendrites. This may be the cause of the failure observed in Figure 10.…”