Method for measuring contents of ester solvents and additives in sodium-ion battery electrolyte by GC-MS (Gas Chromatography-Mass Spectrometer)

Abstract

The invention discloses a method for determining the contents of ester solvents and additives in a sodium-ion battery electrolyte by GC-MS. Through preparation of a diluent, selection of a program method and control of conditions, the types and contents of the solvents and the additives in the sodium-ion battery electrolyte can be rapidly and accurately determined in one step. Therefore, the method can be widely applied to the field of component analysis of the sodium-ion battery electrolyte.

Description

Technical Field

[0001] The invention relates to the technical field of chemical analysis, and in particular to a method for determining the contents of ester solvents and additives in a sodium ion battery electrolyte by GC-MS. Background Art

[0002] With the reduction of traditional fossil energy reserves and the environmental problems caused by mining and utilization, countries have stepped up their efforts in the research and development and utilization of new energy technologies, aiming to achieve energy structure transformation and upgrading and promote sustainable economic and social development. Lithium-ion battery energy storage technology has made great progress in energy storage density and technical maturity, and has been widely used in electric vehicles, large-scale energy storage and other fields.

[0003] Compared with the shortcomings of lithium-ion batteries, such as low abundance of lithium resources in the earth's crust, uneven distribution, and high battery costs, sodium-ion batteries have become a potential alternative to lithium-ion batteries due to their abundant resources and low costs. In recent years, their research and development have developed rapidly around the world, showing broad application prospects.

[0004] In the sodium-ion battery system, the electrolyte is an important component. It not only serves as a medium for ion transmission between the positive and negative electrodes, but also plays a key role in balancing and transferring the charge between the two electrodes. However, the current research focus of the sodium-ion battery system is still on the positive and negative electrode materials, and there are relatively few systematic studies on electrolytes. It is worth noting that since sodium is more reactive than lithium, it reacts more easily with organic solvents. Therefore, it is particularly important to choose a suitable electrolyte in the sodium-ion battery system.

[0005] The electrolyte is generally divided into three parts: solvent, electrolyte salt and additive. As the main components of the electrolyte, the selection and ratio of different solvents and additives are very important in the battery. Due to the large number of solvents and additives in the electrolyte, various electrolyte solutions and additives cannot be separated in the spectrum, and quantitative analysis is relatively cumbersome, which creates great difficulties for analysis and detection. At the same time, the NMR and MS spectra in the prior art cannot fully analyze and detect all types of solvents and additives in the electrolyte, and the current quantitative means of solvents and additives in sodium ion battery electrolytes are relatively simple, and can only rely on single standards or nuclear magnetic internal standards for quantification, which is relatively cumbersome.

[0006] Therefore, there is an urgent need for a simple and efficient method for directly qualitatively and quantitatively detecting solvents and additives in sodium ion battery electrolytes. Summary of the invention

[0007] Purpose of the invention: In view of the defects of the prior art, the purpose of the present invention is to provide a simple and efficient GC-MS method for determining the content of ester solvents and additives in sodium ion battery electrolyte.

[0008] Technical solution:

[0009] A method for determining the content of ester solvents and additives in a sodium ion battery electrolyte by GC-MS comprises the following steps:

[0010] S1: Add a diluent to the sodium ion battery electrolyte to be tested, shake well, centrifuge, and filter to obtain the electrolyte to be tested;

[0011] S2: prepare the test solution, measure the test solution in SCAN and SIM modes, and determine the characteristic qualitative and quantitative ion peaks of each component in the test solution;

[0012] S3: Determine the electrolyte to be tested obtained in S1 according to the method of S2, and perform qualitative analysis on the components to be tested in the electrolyte to be tested;

[0013] S4: Weigh at least three groups of components to be tested as determined in S3, wherein the concentrations of the components to be tested in each group are different and the mass percentages of the components to be tested are consistent, and add a diluent to obtain at least three groups of standard solutions with different concentrations;

[0014] S5: using the ion monitoring mode of the gas chromatography-mass spectrometer to detect each of the standard solutions, and recording the peak area corresponding to each of the standard solutions, and drawing a standard curve according to the content and peak area of ​​each component to be measured in each standard solution, and obtaining a linear equation of the standard curve;

[0015] S6: Detect the test solution in the same manner as in S5, record the peak area, and calculate the concentration of the test component in the sodium ion battery electrolyte according to the linear equation of the standard curve.

[0016] Furthermore, the detection liquid contains methyl formate, methyl acetate, 1,3-dioxolane, dimethyl carbonate, 1,2-dimethoxyethane, ethyl methyl carbonate, methyl butyrate, dimethyl sulfite, vinylene carbonate, diethyl carbonate, vinyl sulfite, trifluoropropylene carbonate, fluoroethylene carbonate, γ-butyrolactone, propylene sulfite, diethylene glycol dimethyl ether, vinyl carbonate, propylene carbonate, butylene carbonate, and triethylene glycol dimethyl ether.

[0017] The solvents and additives of sodium ion battery electrolyte that can be qualitatively and quantitatively detected by the detection method of the present invention are not limited to the above 20 types.

[0018] Furthermore, the detection solution also contains a carboxylate or carbonate organic solvent.

[0019] Furthermore, the detection solution further comprises at least one of vinyl ethylene carbonate, ethylene sulfate, styrene carbonate, tris(trimethylsilyl)phosphoric acid, benzoic anhydride and sulfolane.

[0020] If there are new solvents or additives that need to be tested in the detection method of the present invention, the program method can be used directly to verify the addition.

[0021] Furthermore, the diluent comprises ethyl acetate and carbon disulfide.

[0022] The present invention selects a specific solvent combination as a diluent for the GC-MS determination of the solvent in the sodium ion battery electrolyte, so that the component to be detected can obtain a stable polarity background, and then its linear range can be expanded, so that the peak area of ​​the chromatographic peak obtained and its concentration can still show a good linear relationship under a lower concentration level, thereby expanding the concentration range of the detection.

[0023] Furthermore, the mass ratio of ethyl acetate to carbon disulfide is (6-10):(1-3).

[0024] Furthermore, the diluent further comprises at least one of methanol, ethanol, acetone and N,N-dimethylformamide.

[0025] The present invention can further improve the stability of the polar background and the separation effect between the components by further adding a diluent component, thereby improving the reproducibility and accuracy of the detection.

[0026] Furthermore, the chromatographic conditions of the GC-MS are as follows: the chromatographic column is an Agilent HP-5 capillary column with a specification of 50m×0.32mm×1μm; the carrier gas is nitrogen with a constant flow rate and a column flow rate of 1-1.5mL / min; the injection volume is 0.75-1.25μL; the injection mode is split with a split ratio of 25-100:1; and the transmission line temperature is 260-300°C.

[0027] Furthermore, the column temperature of the GC-MS adopts a programmed temperature rising method, with the starting temperature at 30-35°C, kept constant for 3-8 minutes, heated to 100°C at a heating rate of 15-25°C / min, kept constant for 3-8 minutes, heated to 125°C at a heating rate of 10-20°C / min, kept constant for 2-6 minutes, and heated to 160°C at a heating rate of 5-15°C / min, kept constant for 1-3 minutes.

[0028] The present invention can effectively separate the solvent and additive in the electrolyte of the sodium ion battery by controlling the chromatographic conditions of GC-MS and the temperature rise program of the column temperature, thereby improving the accuracy of detection.

[0029] Furthermore, the mass spectrometry conditions of the GC-MS are: the ionization mode is EI; the solvent delay time is 2-2.5 min.

[0030] Beneficial effects:

[0031] (1) The GC-MS method provided by the present invention for determining the content of ester solvents and additives in sodium ion battery electrolyte can determine the type and content of solvents and additives in sodium ion battery electrolyte in one step, quickly and accurately, through the preparation of diluents, the selection of program methods and the control of conditions, and can be widely used in the field of component analysis of sodium ion battery electrolyte.

[0032] (2) The GC-MS method provided by the present invention for determining the content of ester solvents and additives in sodium ion battery electrolytes can provide a stable polar background for the components to be detected by compounding ethyl acetate and carbon disulfide as diluents for the components to be detected, thereby expanding their linear range, so that the peak area of ​​the chromatographic peak obtained and its concentration can still show a good linear relationship at a lower concentration level, thereby expanding the concentration range of detection.

[0033] (3) The GC-MS method provided by the present invention for determining the content of ester solvents and additives in sodium ion battery electrolytes can effectively separate the solvents and additives by establishing a new gas chromatogram of common ester solvents and additives to analyze and detect sodium ion battery electrolytes, thereby quickly and accurately performing quantitative and qualitative analysis, thereby improving the detection efficiency and the range of components detected.

[0034] (4) The GC-MS method provided by the present invention for determining the content of ester solvents and additives in sodium ion battery electrolyte can effectively separate the solvents and additives in the sodium ion battery electrolyte by adjusting the split ratio, carrier gas flow rate and programmed temperature conditions of the instrument in the program method, and obtain a completely separated GC graph.

[0035] (5) The GC-MS method provided by the present invention for determining the content of ester solvents and additives in sodium ion battery electrolyte can effectively improve the detection efficiency by selecting the program method and controlling the conditions. The running time of GC-MS is longer than 16 minutes, which can significantly improve the efficiency of sodium ion battery electrolyte component detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is the GC chart of the detection liquid in the embodiment of the present invention. DETAILED DESCRIPTION

[0037] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following examples are examples of the present invention and are only used to illustrate the present invention, but are not used to limit the present invention. Without departing from the gist or scope of the present invention, other combinations and various improvements within the concept of the present invention may be carried out. The reagents and equipment in the present invention are conventional reagents and equipment in the art.

[0038] Example

[0039] A gas chromatograph-mass spectrometer was used, and the chromatographic conditions were as follows: the chromatographic column was an Agilent HP-5 capillary column with a specification of 50m×0.32mm×1μm; the carrier gas was nitrogen with a constant flow rate of 1mL / min; the injection volume was 1μL; the injection mode was split with a split ratio of 50:1; the transfer line temperature was 300℃;

[0040] The column temperature was programmed, starting at 35 °C for 5 min, then heated to 100 °C at a rate of 20 °C / min, then heated to 125 °C at a rate of 15 °C / min, then heated to 160 °C at a rate of 10 °C / min, then heated to 2 min.

[0041] The mass spectrometry conditions were as follows: ionization mode was EI; solvent delay time was 2 min;

[0042] The content of ester solvents and additives in sodium ion battery electrolyte is detected by the following steps:

[0043] S1: Add a diluent to the sodium ion battery electrolyte to be tested, shake well, centrifuge, and filter to obtain the electrolyte to be tested;

[0044] The diluent is prepared by mixing ethyl acetate and carbon disulfide in a mass ratio of 8:2;

[0045] S2: Prepare the test solution, measure the test solution in SCAN and SIM mode, determine the characteristic qualitative and quantitative ion peaks of each component in the test solution, and obtain Figure 1 ;

[0046] The detection liquid includes methyl formate, methyl acetate, 1,3-dioxolane, dimethyl carbonate, 1,2-dimethoxyethane, ethyl methyl carbonate, methyl butyrate, dimethyl sulfite, vinylene carbonate, diethyl carbonate, vinyl sulfite, trifluoropropylene carbonate, fluoroethylene carbonate, γ-butyrolactone, propylene sulfite, diethylene glycol dimethyl ether, vinyl carbonate, propylene carbonate, butylene carbonate, and triethylene glycol dimethyl ether;

[0047] S3: Determine the electrolyte to be tested obtained in S1 according to the method of S2, and perform qualitative analysis on the components to be tested in the electrolyte to be tested;

[0048] S4: Weigh three groups of components to be tested as determined in S3, wherein the concentrations of the components to be tested in each group are different and the mass percentages of the components to be tested are consistent, and add a diluent to obtain at least three groups of standard solutions with different concentrations;

[0049] S5: using the ion monitoring mode of the gas chromatography-mass spectrometer to detect each of the standard solutions, and recording the peak area corresponding to each of the standard solutions, and drawing a standard curve according to the content and peak area of ​​each component to be measured in each standard solution, and obtaining a linear equation of the standard curve;

[0050] S6: Detect the test solution in the same manner as in S5, record the peak area, and calculate the concentration of the test component in the sodium ion battery electrolyte according to the linear equation of the standard curve. The specific experimental results are shown in the following table:

[0051]

[0052] According to the test results, the GC-MS method provided by the present invention for determining the content of ester solvents and additives in sodium ion battery electrolyte can determine the types and contents of solvents and additives in sodium ion battery electrolyte in one step, quickly and accurately, with a short overall running time, excellent separation effect and separation range, and can effectively perform qualitative and quantitative analysis on ester solvents and additives in sodium ion battery electrolyte.

[0053] The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining the content of ester solvents and additives in sodium ion battery electrolyte by GC-MS, characterized in that: The following steps are involved: S1: Add a diluent to the sodium ion battery electrolyte to be tested, shake well, centrifuge, and filter to obtain the electrolyte to be tested; S2: prepare the test solution, measure the test solution in SCAN and SIM modes, and determine the characteristic qualitative and quantitative ion peaks of each component in the test solution; S3: Determine the electrolyte to be tested obtained in S1 according to the method of S2, and perform qualitative analysis on the components to be tested in the electrolyte to be tested; S4: Weigh at least three groups of components to be tested as determined in S3, wherein the concentrations of the components to be tested in each group are different and the mass percentages of the components to be tested are consistent, and add a diluent to obtain at least three groups of standard solutions with different concentrations; S5: using the ion monitoring mode of the gas chromatography-mass spectrometer to detect each of the standard solutions, and recording the peak area corresponding to each of the standard solutions, and drawing a standard curve according to the content and peak area of ​​each component to be measured in each standard solution, and obtaining a linear equation of the standard curve; S6: Detect the test solution in the same manner as in S5, record the peak area, and calculate the concentration of the test component in the sodium ion battery electrolyte according to the linear equation of the standard curve.

2. The method for determining the content of ester solvents and additives in sodium ion battery electrolyte by GC-MS according to claim 1, characterized in that: The detection liquid contains methyl formate, methyl acetate, 1,3-dioxolane, dimethyl carbonate, 1,2-dimethoxyethane, ethyl methyl carbonate, methyl butyrate, dimethyl sulfite, vinylene carbonate, diethyl carbonate, vinyl sulfite, trifluoropropylene carbonate, fluoroethylene carbonate, γ-butyrolactone, propylene sulfite, diethylene glycol dimethyl ether, vinyl carbonate, propylene carbonate, butylene carbonate, and triethylene glycol dimethyl ether.

3. The method for determining the content of ester solvents and additives in sodium ion battery electrolyte by GC-MS according to claim 2, characterized in that: The detection solution further comprises a carboxylate or carbonate organic solvent.

4. The method for determining the content of ester solvents and additives in sodium ion battery electrolyte by GC-MS according to claim 2, characterized in that: The detection solution further comprises at least one of vinyl ethylene carbonate, ethylene sulfate, styrene carbonate, tris(trimethylsilyl)phosphoric acid, benzoic anhydride and sulfolane.

5. The method for determining the content of ester solvents and additives in sodium ion battery electrolyte by GC-MS according to claim 1, characterized in that: The diluent comprises ethyl acetate and carbon disulfide.

6. The method for determining the content of ester solvents and additives in sodium ion battery electrolyte by GC-MS according to claim 5, characterized in that: The mass ratio of ethyl acetate to carbon disulfide is (6-10):(1-3).

7. The method for determining the content of ester solvents and additives in sodium ion battery electrolyte by GC-MS according to claim 6, characterized in that: The diluent further comprises at least one of methanol, ethanol, acetone and N,N-dimethylformamide.

8. The method for determining the content of ester solvents and additives in sodium ion battery electrolyte by GC-MS according to claim 1, characterized in that: The chromatographic conditions of the GC-MS are as follows: the chromatographic column is an Agilent HP-5 capillary column with a specification of 50m×0.32mm×1μm; the carrier gas is nitrogen with a constant flow rate and a column flow rate of 1-1.5mL / min; the injection volume is 0.75-1.25μL; the injection mode is split with a split ratio of 25-100:1; and the transmission line temperature is 260-300°C.

9. The method for determining the content of ester solvents and additives in sodium ion battery electrolyte by GC-MS according to claim 1, characterized in that: The column temperature of the GC-MS adopts a programmed temperature rising method, with a starting temperature of 30-35°C, which is kept constant for 3-8 minutes, then heated to 100°C at a heating rate of 15-25°C / min, and kept constant for 3-8 minutes, then heated to 125°C at a heating rate of 10-20°C / min, and kept constant for 2-6 minutes, then heated to 160°C at a heating rate of 5-15°C / min, and kept constant for 1-3 minutes.

10. The method for determining the content of ester solvents and additives in sodium ion battery electrolyte by GC-MS according to claim 1, characterized in that: The mass spectrometry conditions of the GC-MS are: the ionization mode is EI; the solvent delay time is 2-2.5 min.

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