XPS characterization of the reactions of Li with tetrahydrofuran and propylene carbonate

Zhuang, Guorong V.; Wang, Kuilong; Ross, Philip N.

doi:10.1016/s0039-6028(97)00353-1

Cited by 25 publications

(21 citation statements)

References 15 publications

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“…4 Experiments designed to assess the relative reactivity of various solvents toward metallic Li reported by Aurbach et al showed that the ethers require periods of weeks for products to be clearly detected, 1 whereas ester-based and alkyl carbonates react over minutes to hours. The results obtained for THF are difficult to reconcile with those reported by Ross et al, 6 who identified Li alkoxide as the main reaction product at room temperature based on XPS analysis of THF layers initially frozen at cryogenic temperatures and later heated in stages to high temperatures. As we have suggested in earlier communications, this effect could well reflect photoelectron-induced decomposition of these rather fragile organic materials owing to excessive X-ray irradiation.…”

Section: Scheme 1 Proposed Reaction Mechanism Between Metallic LI Ancontrasting

confidence: 74%

Reactivity of Metallic Lithium Toward γ-Butyrolactone, Propylene Carbonate, and Dioxalane

Rendek¹,

Chottiner²,

Scherson³

2003

J. Electrochem. Soc.

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The nature of the reaction products generated by exposure of a model cyclic ester, ␥-butyrolactone ͑␥-BL͒, two cyclic ethers, dioxalane ͑DIOX͒ and tetrahydrofuran ͑THF͒, and a cyclic alkyl carbonate, propylene carbonate ͑PC͒, toward metallic Li at room temperature was examined in ultrahigh vacuum by infrared reflection absorption, Auger electron ͑AES͒, and X-ray photoelectron ͑XPS͒ spectroscopies. The features observed in the spectra were consistent with Li butyrate and Li ␤-keto ester in the case of ␥-BL, and a dialkoxide derivative of Li with small amounts of Li oxide for experiments involving PC as the main reaction products. The behavior of both these solvents differs greatly from that found of the cyclic ethers DIOX and THF, for which the XPS spectra yielded small amounts of Li oxide and Li carbide as the only reaction products. These two species are most likely not derived from reactions involving DIOX or THF but rather from reactions between metallic Li and CO desorbed from the walls of the chamber during prolonged dosings. The extent of the reaction involving ␥-BL, as evidenced by the loss of the AES peak at 52 eV characteristic of metallic Li, far exceeded that observed with PC and the linear alkyl carbonates reported previously in this laboratory, for which the aforementioned feature could be discerned clearly even after extensive exposure. All these findings agree with those reported by Aurbach et al. 1 for experiments involving Li metal exposure to the same solvents in liquid phase, which suggests that conclusions drawn from ex situ experiments of the type originally devised by our research group may also be applicable to reactions in condensed phase, including electrochemical environments.Procedures have been developed in our research group for the identification of reaction products formed on clean Li surfaces upon exposure to solvents of relevance to lithium batteries in gas phase. These experiments are carried out in ultrahigh vacuum ͑UHV͒, using infrared reflection absorption spectroscopy ͑IRAS͒, Auger electron spectroscopy ͑AES͒ and X-ray photoelectron ͑XPS͒ spectroscopy as complementary vibrational and electronic probes. This paper extends the suite of linear and cyclic alkyl carbonates investigated in previous work, to ␥-butyrolactone ͑␥-BL͒, a model cyclic ester, as well as 1,3-dioxalane ͑DIOX͒ and tetrahydrofuran ͑THF͒, two model cyclic ethers, to compare the reactivity of these latter solvents toward metallic Li with that of linear alkyl carbonates. ExperimentalAll measurements were performed in a custom designed UHV chamber equipped with instrumentation required for the cleaning of Li specimens and their subsequent spectral characterization with AES, XPS, and IRAS. 2 As described elsewhere, p-polarized infrared ͑IR͒ light emerging from a Mattson Cygnus 25 Fourier transform IR ͑FTIR͒ spectrometer was focused at an incident angle of 69°onto the surface of a coin-shaped Li foil ͑ca. 12 mm diam, 1 mm thick͒ mounted onto the UHV sample stage ͑see below͒. As is customary, IRAS spectra are report...

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Section: Scheme 1 Proposed Reaction Mechanism Between Metallic LI Ancontrasting

confidence: 74%

Reactivity of Metallic Lithium Toward γ-Butyrolactone, Propylene Carbonate, and Dioxalane

Rendek¹,

Chottiner²,

Scherson³

2003

J. Electrochem. Soc.

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“…et al 15 Both organic molecules react with the lithium layer and were decomposed. The authors claim the decomposition is based on ring-opening, too.…”

Section: Discussionmentioning

confidence: 99%

“…Replacing the organic solvents by ionic liquids has been widely tested and promises to be a good compromise between performance, safety and stability. [12][13][14] The interaction of lithium with organic solvents for battery applications like tetrahydrofuran (THF) and propylene carbonate (PC) has been done for instance by Zhuang et al 15 They evaporated thin films of THF and PC in a UHV chamber on a lithium layer and observed a lithium induced decomposition of the organic molecules by using photoelectron spectroscopy (XPS). In the present paper the stability of 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([OMIm]Tf 2 N) against lithium has been investigated by vapor depositing a thin film of the RT-IL on top of a lithium covered copper substrate.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic characterization of the interaction of lithium with thin films of the ionic liquid 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide

Olschewski

Gustus

Marschewski

et al. 2014

Phys. Chem. Chem. Phys.

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In this experimental investigation the interaction of lithium with 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([OMIm]Tf2N) is shown. For this purpose thin films of lithium and [OMIm]Tf2N were successively vapor deposited on a copper substrate and analyzed by X-ray Photoelectron Spectroscopy (XPS) as well as by Ultraviolet Photoelectron Spectroscopy (UPS). When [OMIm]Tf2N is evaporated on top of a thin lithium film a chemical shift analysis of XPS spectra shows a variety of reaction products like LiF, Li2O and LixCHy which reveals the instability of the IL against lithium. Time resolved XPS spectra were discussed to distinguish cation reactions from beam damage effects. In a second step lithium is deposited on a [OMIm]Tf2N layer. The XPS spectra are in agreement with the results of the previous step, but show some differences concerning the [OMIm] cation. In a third step [OMIm]Tf2N has been deposited on a passivated lithium layer. XPS results show nearly unaffected [Tf2N](-) anions and partially decomposed [OMIm](+) cations. Interestingly the cation reactions show similarities when compared to the interaction of [C4C1Pyrr]Tf2N (1-butyl-1-methylpyrrolidinium bis[trifluoromethylsulfonyl]amide) and lithium.

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“…300 K C(1s) features at 285 and 287 eV and O(1s) peaks at 530.5 and 532.5 eV. Ross and co-workers implemented the techniques developed at CWRU by condensing layers of THF on Li supported on Al at 120 K followed by XPS characterization after heating the specimen in stages and found both C(1s) and O(1s) features up to 620 K. 23 However, the XPS features observed by these authors at 320 K occurred at binding energies of 288.3 and 287.1 eV for C(1s) and 535.8 and 532.5 eV for O(1s), which are different than those of Wang et al 4 It thus seems plausible that the differences between the results obtained by these two groups are due to electron beam damage, although effects due to prolonged exposure of species in the condensed phase to reactive surfaces even at cryogenic temperatures could also play a role. Experiments involving IRAS monitoring of condensed films before and after X-ray irradiation may shed light into some of these issues; however, our current chamber design does not allow for such measurements to be carried out without rotating the specimens, a procedure found to seriously compromise acquisition of reliable ∆R/R spectra.…”

Section: Methodsmentioning

confidence: 99%

Reactivity of Linear Alkyl Carbonates toward Metallic Lithium: Infrared Reflection−Absorption Spectroscopic Studies in Ultrahigh Vacuum

2002

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The reactivity of symmetric and asymmetric alkyl linear carbonates of the type ROCO2R′, where R and R′ represent methyl or ethyl groups, toward metallic Li was studied by infrared reflection-absorption spectroscopy (IRAS) in ultrahigh vacuum. Comparison of the IRAS spectra of clean Li surfaces exposed to dimethyl, diethyl (DEC), and ethyl-methyl carbonates (EMC) with those obtained in very similar experiments involving judiciously selected alcohols provided unambiguous evidence that the products of such reactions are primarily Li alkoxides (ROLi and R′OLi). Spectral evidence was also found for the presence of Li ethyl carbonate for experiments involving DEC and EMC. No changes in the IRAS spectra could be discerned upon exposure of RCO2R′-reacted Li surfaces to large doses of CO2 at ca. 300 K. Furthermore, predosing Li surfaces with CO2 at 300 K to form small amounts of Li2CO3 prior to exposure to ROCO2R′ did not alter the nature of the reaction products. The conclusions emerging from this study support by and large the mechanism proposed by Aurbach et al. for reactions between Li and condensed phase linear and cyclic alkyl carbonates.

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XPS characterization of the reactions of Li with tetrahydrofuran and propylene carbonate

Cited by 25 publications

References 15 publications

Reactivity of Metallic Lithium Toward γ-Butyrolactone, Propylene Carbonate, and Dioxalane

Reactivity of Metallic Lithium Toward γ-Butyrolactone, Propylene Carbonate, and Dioxalane

Spectroscopic characterization of the interaction of lithium with thin films of the ionic liquid 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide

Reactivity of Linear Alkyl Carbonates toward Metallic Lithium: Infrared Reflection−Absorption Spectroscopic Studies in Ultrahigh Vacuum

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