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

Kraft, Vadim; Weber, Waldemar; Streipert, Benjamin; Wagner, Ralf; Schultz, Carl; Winter, Martin; Nowak, Sascha

doi:10.1039/c5ra23624j

Cited by 76 publications

(53 citation statements)

References 41 publications

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“…Accordingly, DMP reacted completely to other decomposition products from the electrolyte mixture. The following OPs were determined in the aged sample: (2) [37,41,[43][44][45][46]. In the electropherogram ( Figure 5), some of the reported m/z ratios were detected.…”

Section: Application For the Investigation Of Decomposition Products mentioning

confidence: 99%

Capillary Electrophoresis as Analysis Technique for Battery Electrolytes: (i) Monitoring Stability of Anions in Ionic Liquids and (ii) Determination of Organophosphate-Based Decomposition Products in LiPF6-Based Lithium Ion Battery Electrolytes

Pyschik¹,

Winter²,

Nowak³

2017

Separations

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Abstract:In this work, a method for capillary electrophoresis (CE) hyphenated to a high-resolution mass spectrometer was presented for monitoring the stability of anions in ionic liquids (ILs) and in commonly used lithium ion battery (LIB) electrolytes. The investigated ILs were 1-methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR 13 TFSI) and 1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide (PYR 13 FSI). The method development was conducted by adjusting the following parameters: buffer compositions, buffer concentrations, and the pH value. Also the temperature and the voltage applied on the capillary were optimized. The ILs were aged at room temperature and at 60 • C for 16 months each. At both temperatures, no anionic decomposition products of the FSI − and TFSI − anions were detected. Accordingly, the FSI − and TFSI − anions were thermally stable at these conditions. This method was also applied for the investigation of LIB electrolyte samples, which were aged at 60 • C for one month. The LP30 (50/50 wt. % dimethyl carbonate/ethylene carbonate and 1 M lithium hexafluorophosphate) electrolyte was mixed with the additive 1,3-propane sultone (PS) and with one of the following organophosphates (OP): dimethyl phosphate (DMP), diethyl phosphate (DEP), and triethyl phosphate (TEP), to investigate the influence of these compounds on the formation of OPs.

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Section: Application For the Investigation Of Decomposition Products mentioning

confidence: 99%

Capillary Electrophoresis as Analysis Technique for Battery Electrolytes: (i) Monitoring Stability of Anions in Ionic Liquids and (ii) Determination of Organophosphate-Based Decomposition Products in LiPF6-Based Lithium Ion Battery Electrolytes

Pyschik¹,

Winter²,

Nowak³

2017

Separations

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“…There is a little peak at t = 1.88 min which was identified as propionitrile, an impurity intrinsic to acetonitrile. At short times, there are two peaks which are assigned to POF 3 (t = 1.28 min) 25 and PF 5 (t = 1.39 min). 26 These compounds come from the PF 6 − anion thermal degradation according to the following reaction:…”

Section: Xps Analysis Of Lithiated Graphite Interfaces-symmetricmentioning

confidence: 99%

Reactivity of Succinic Anhydride at Lithium and Graphite Electrodes

Charton

Santos-Peña

Biller

et al. 2017

J. Electrochem. Soc.

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Succinic anhydride (SA) is an useful electrolyte additive for high voltage cathodes but has also a negative impact on graphite (Gr) or Li anodes. For this reason, the Li/electrolyte and Gr/electrolyte interfaces were investigated at 20 • C and 45 • C using half or symmetrical cells. When SA is added at 1% by weight to the electrolyte (alkylcarbonate mixture + LiPF 6 ), an increase in the Li/Li cell impedance at 20 • C occurs owing to the formation of a resistive solid electrolyte interphase (SEI), composed of an inorganic inner layer and an organic outer layer, whereas at 45 • C or in absence of SA, the interphase is more inorganic in nature. The reversible capacity of graphite, cycled in Gr/Li half-cells in the presence of SA, is very low at 20 • C but almost ten times larger at 45 • C. Cycling symmetrical Gr/Gr cells at 45 • C indicates that Gr capacity is lower in the presence of SA in connection with the presence of an organic and polymer rich SEI. GC-MS analysis of the electrolyte after cycling shows that ethylene glycol bis-(alkylcarbonate) derivatives disappear when SA is present, owing to the ability of SA to react with lithium alkoxides to yield oligopolyester. Lithium ion batteries (LIBs) are a reliable way to store electric energy, with high gravimetric and volumetric energy density, which allows their application in nomad systems including electric and/or hybrid vehicles. However, electric vehicles range is unsuitable for most of the consumers and, therefore, energy density should be improved. In the past twenty years, many researches have been performed on electrode materials and electrolytes with the aim to enhance battery performance. Use of 5V class positive electrodes (cathodes) is a convenient way to increase LIBs energy density. It explains the development of promising "high voltage" materials like Li 3 V 2 (PO 4 ) 3 , 1 Li 2 CoPO 4 F 2 or the LiNi 0.5 Mn 1.5 O 4 (LNMO) 3 spinel. Nevertheless, the use of new cathodes operating at high voltage leads to the degradation of the battery electrolyte, usually based on a mixture of cyclic and linear alkylcarbonates containing LiPF 6 as salt and functional additives. Unfortunately, standard electrolytes are oxidized on 5 V cathodes and this significantly limits the battery cycling life. From the first cycles, electrolyte components degrade forming by-products, which in turn, can interact with electrodes surface. As an example, a passive layer is formed on graphite (Gr)/electrolyte interface at the first charge. This layer, known as the Solid Electrolyte Interphase (SEI), has a strong impact on the LIBs performances. Electrolyte formulation influences the chemical nature and structure of the SEI. With the aim to improve SEI quality and stability, SEI-forming additives like vinylene carbonate (VC) are generally added to the electrolyte in low amount (less than 5% by weight). These additives are designed to generate a protective passive layer on the active material surface preventing continuous electrolyte decomposition reactions.Whereas additives can be ...

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“…[7][8][9][10][11][12][13][14][15][16][17][18][19][20] These instruments are costly, and these methods require the preparation and measurement of many calibration solutions. Often the columns or detectors used in chromatography experiments cannot be exposed to the high temperature decomposition products of LiPF 6 , so these experiments often focus on the organic portions of the electrolyte, after the water-soluble portions of the electrolyte have been removed.…”

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confidence: 99%

A New Method for Determining the Concentration of Electrolyte Components in Lithium-Ion Cells, Using Fourier Transform Infrared Spectroscopy and Machine Learning

Ellis

Buteau

Hames

et al. 2018

J. Electrochem. Soc.

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A new method is introduced for determining unknown concentrations of major components in typical lithium-ion battery electrolytes. The method is quick, cheap, and accurate. Machine learning techniques are used to match features of the Fourier transform infrared (FTIR) spectrum of an unknown electrolyte to the same features of a database of FTIR spectra with known compositions. With this method, LiPF 6 concentrations can be determined with similar accuracy and precision as an inductively coupled plasma optical emission spectrometry (ICP-OES) method. The ratios of organic carbonate solvent species can be determined with more rapidity than gas chromatography (GC). This FTIR method is faster and less expensive than GC and ICP-OES, and has the added benefit of being able to determine LiPF 6 concentration and solvent fractions simultaneously. Application of this tool can facilitate electrolyte analysis of aged lithium-ion cells, and will help elucidate mechanisms for cell degradation. A dominant cause of lithium-ion cell failure, especially in high voltage cells, is degradation of the electrolyte, particularly at the surface of the charged electrodes.1 Most studies on the topic of cell degradation and electrolyte decomposition have focused on the formation of films of electrolyte decomposition products which build up on the surfaces of the electrodes.2-6 These films contain chemical moieties derived from both the electrolyte solvents and the electrolyte salt, LiPF 6 . Although mechanisms for the consumption of solvents and LiPF 6 in lithium-ion cells have been determined, there have been few systematic studies which quantify the changes in the bulk electrolyte as a function of cell aging.Quantitative analyses of electrolyte solutions typically employ nuclear magnetic resonance (NMR) spectroscopy, gas chromatography (GC), high performance liquid chromatography (HPLC), and inductively coupled plasma optical emission spectrometry (ICP-OES). [7][8][9][10][11][12][13][14][15][16][17][18][19][20] These instruments are costly, and these methods require the preparation and measurement of many calibration solutions. Often the columns or detectors used in chromatography experiments cannot be exposed to the high temperature decomposition products of LiPF 6 , so these experiments often focus on the organic portions of the electrolyte, after the water-soluble portions of the electrolyte have been removed. 20A method of determining the concentration of LiPF 6 and weight fractions of solvents in unknown electrolyte solutions, using attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy is presented here. Until now, FTIR has only been used for qualitative electrolyte analysis, and for the determination of solvation structures. Quantitative analysis was achieved using a machine learning (ML) algorithm to match features in the FTIR spectra of unknown electrolyte solutions to those interpolated from a spectral database of known electrolyte solutions. This method is very fast. Once the spectral database and mac...

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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

Cited by 76 publications

References 41 publications

Capillary Electrophoresis as Analysis Technique for Battery Electrolytes: (i) Monitoring Stability of Anions in Ionic Liquids and (ii) Determination of Organophosphate-Based Decomposition Products in LiPF6-Based Lithium Ion Battery Electrolytes

Capillary Electrophoresis as Analysis Technique for Battery Electrolytes: (i) Monitoring Stability of Anions in Ionic Liquids and (ii) Determination of Organophosphate-Based Decomposition Products in LiPF6-Based Lithium Ion Battery Electrolytes

Reactivity of Succinic Anhydride at Lithium and Graphite Electrodes

A New Method for Determining the Concentration of Electrolyte Components in Lithium-Ion Cells, Using Fourier Transform Infrared Spectroscopy and Machine Learning

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