Investigation of thermal aging and hydrolysis mechanisms in commercial lithium ion battery electrolyte

The presented work was focused on the development of a new liquid chromatography-tandem quadrupole mass spectrometry method (LC-MS/MS) for the identification and quantification of organophosphates in lithium hexafluorophosphate (LiPF 6 )-based lithium ion battery electrolytes. The investigated electrolyte consists of 1 M LiPF 6 dissolved in ethylene carbonate/ethyl methyl carbonate (50/50, wt%) and was treated electrochemically and thermally. For the electrochemical experiments, the cut-off potential in the half cells was held at 5.5 V for 72 h. The thermal degradation experiments were performed in aluminum vials at 95 C for a period of 13 days. In the first part of this work, an already established gas chromatography-mass spectrometry (GC-MS) method for identification of dimethyl fluorophosphates (DMFP) and diethyl fluorophosphate (DEFP) was applied. In the second part, the LC-MS/MS method including determination of characteristic transitions in a product ion scan was developed. The developed method was applied for the identification of various analytes in the decomposed electrolytes. In addition, a possible formation of ionic and non-ionic OPs based on findings of this work and our previous reports is presented. In the third and final part, a quantification study of DMFP and DEFP was performed with a newly developed LC-MS/MS method and compared with results obtained by GC-MS. In addition, trimethyl phosphate (TMP) and triethyl phosphate (TEP) were quantified. These studies included the investigation of the suppression effects caused by the sample matrix during the application of the LC-MS/MS method.

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“…The separations were carried out on an Acclaim™ 120 column (C18, 4.6 Â 250 mm, Thermo Scientic) at 30 C column oven temperature with 40%…”

Section: Lc-esi-ms Conditionsmentioning

confidence: 99%

Qualitative and quantitative investigation of organophosphates in an electrochemically and thermally treated lithium hexafluorophosphate-based lithium ion battery electrolyte by a developed liquid chromatography-tandem quadrupole mass spectrometry method

et al. 2016

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“…By application of different analysis techniques numerous aging products were identied, including HF, 9-13 inorganic or organic phosphates (OPs), 11,[14][15][16][17][18]41 23 was proven. Other decomposition products like organic uorophosphates are critical due to their high toxicity.…”

Section: Introductionmentioning

confidence: 99%

Study of decomposition products by gas chromatography-mass spectrometry and ion chromatography-electrospray ionization-mass spectrometry in thermally decomposed lithium hexafluorophosphate-based lithium ion battery electrolytes

et al. 2015

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In this work, the thermal decomposition of a lithium ion battery electrolyte (1 M LiPF 6 in ethylene carbonate/ ethyl methyl carbonate, 50/50 wt%) with a focus on the formation of organophosphates was systematically studied. The quantification of non-ionic dimethyl fluorophosphate and diethyl fluorophosphate was performed with synthesized standards by gas chromatography-mass spectrometry. Due to absence of commercially available or synthesized standards for the monitoring of ionic methyl fluorophosphate, ethyl fluorophosphate and ethylene phosphate a method working with ion chromatography-electrospray ionization-mass spectrometry was developed, where dibutyl phosphate was used as an internal standard.In addition, an ion chromatography conductivity detection method with short analysis time for simultaneous determination and quantification of F À , PF 6 À and BF 4 À was developed. The formation and degradation of analytes was studied to show the dependence of different temperatures, electrolyte volumes and separator materials. The thermal aging experiments were carried out in gas-tight aluminum vials at 80 C for three weeks. After the storage time, the samples were diluted with the appropriate analysis solvents and investigated with gas chromatography-mass spectrometry, ion chromatography and ion chromatography-electrospray ionization-mass spectrometry. Finally, the thermal degradation of the electrolyte at 85 C after five days in aluminum and glass vials was studied.

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“…However, LIBs suffer from severe performance degradation due to undesired chemical reactions, 1 ageing, 2,3 corrosion, [4][5][6] compromised structural integrity, 7,8 and thermal runaway. [9][10][11] The degradation occurs during both calendar and cycling lifespans, and reduces the longevity of LIBs. Recently, much attention has been focused on LIB material decomposition, 12 e.g., the formation and growth of new components [13][14][15][16][17][18][19] due to undesired side reactions.…”

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Simulation and Experiment on Solid Electrolyte Interphase (SEI) Morphology Evolution and Lithium-Ion Diffusion

Guan

Liu

Lin

2015

J. Electrochem. Soc.

154

118

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In this study, a phase-field model is developed to simulate the microstructure morphology evolution that occurs during solid electrolyte interphase (SEI) growth. Compared with other simulation methodologies, the phase-field method has been widely applied in the solidification modeling that has great relevance to SEI formation. The developed model can simulate SEI structure and morphology evolution, and can predict SEI thickness growth rate. X-ray photoelectron spectroscopy (XPS) experiments are performed to confirm the major SEI species as LiF, Li 2 O, ROLi, and ROCO 2 Li. Transmission electron microscopy (TEM) experiment is performed to present the SEI layer structures. The experiments reduce the complexity of the model development and provide validation to some extent. Fick's law and mass balance are applied to investigate lithium-ion concentration distributions and diffusion coefficients in different types of SEI layers predicted by the phase-field simulations. Simulation results show that lithium-ion diffusion coefficients between 298 K and 318 K are 1. 340-7.328 Lithium-ion batteries (LIBs) are widely used in many applications, such as cell phones, electric vehicles (EVs), and other energy storage modules. However, LIBs suffer from severe performance degradation due to undesired chemical reactions, 1 ageing, 2,3 corrosion, 4-6 compromised structural integrity, 7,8 and thermal runaway. 9-11 The degradation occurs during both calendar and cycling lifespans, and reduces the longevity of LIBs. Recently, much attention has been focused on LIB material decomposition, 12 e.g., the formation and growth of new components [13][14][15][16][17][18][19] due to undesired side reactions. 1,20 The main degradation mechanisms in LIBs vary with different active materials, 2 however, it is well known that a carbonaceous lithium-intercalation electrode in contact with electrolyte solution becomes covered by a passivation layer called a solid electrolyte interphase (SEI). While SEI can prevent the exfoliation of graphite materials and inhibit further electrolyte decomposition.21 SEI layer growth can also cause battery capacity fade and increase cell internal resistance. 17,[22][23][24][25][26] Therefore, the study of SEI plays a key role in battery degradation and other related performance improvement research. Many studies have been published in SEI computational and experimental studies, including but not limited to. [27][28][29][30] Many researchers have investigated SEI in LIBs in terms of structure, 7,8,29,31-33 formation and composition, 20,22,27 and thickness growth prediction and measurement. 15,16,34,35 SEI is believed to have a multilayered structure: a compact layer of inorganic components (e.g., LiF, Li 2 O) close to graphite electrode followed by a porous organic layer (e.g., ROLi, ROCO 2 Li) close to the electrolyte solution phase. 22,29,[31][32][33] The composition of SEI depends on the electrode materials and electrolyte composition.27 Broussely et al. investigated the mechanism of lithium loss in LIBs during ...

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Investigation of thermal aging and hydrolysis mechanisms in commercial lithium ion battery electrolyte

Cited by 134 publications

References 19 publications

Qualitative and quantitative investigation of organophosphates in an electrochemically and thermally treated lithium hexafluorophosphate-based lithium ion battery electrolyte by a developed liquid chromatography-tandem quadrupole mass spectrometry method

Qualitative and quantitative investigation of organophosphates in an electrochemically and thermally treated lithium hexafluorophosphate-based lithium ion battery electrolyte by a developed liquid chromatography-tandem quadrupole mass spectrometry method

Study of decomposition products by gas chromatography-mass spectrometry and ion chromatography-electrospray ionization-mass spectrometry in thermally decomposed lithium hexafluorophosphate-based lithium ion battery electrolytes

Simulation and Experiment on Solid Electrolyte Interphase (SEI) Morphology Evolution and Lithium-Ion Diffusion

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