A method for high-precision detection of 1,3-propenesulfonate lactone content in electrolyte

Abstract

This invention relates to a high-precision detection method for the content of 1,3-propenesulfonate lactone (PST) in an electrolyte, comprising: dissolving PST in an organic solvent to prepare a set of PST standard solutions with a concentration gradient; selecting a chromatographic column with a stationary phase of 5% phenyl-95% dimethyl polysiloxane, a column length of 25-60 m, an inner diameter of 0.25-0.50 mm, and an inner coating thickness of 0.25-0.50 μm; adjusting the test parameters of a gas chromatography-mass spectrometry (GC-MS); detecting each PST standard solution in the PST standard solution set using the GC-MS with adjusted parameters, recording the detection peak area corresponding to each PST standard solution, and determining a standard curve based on the PST concentration; pretreating the electrolyte to be tested, detecting the pretreated electrolyte using the GC-MS with adjusted parameters, obtaining the measured detection peak area, and finding the corresponding PST concentration in the electrolyte by searching the standard curve based on the measured detection peak area.

Description

Technical Field

[0001] This invention relates to the field of electrolyte detection, and more particularly to a method for high-precision detection of the content of 1,3-propenesulfonate lactone in electrolyte. Background Technology

[0002] Lithium-ion batteries are widely used in new energy vehicles, digital products, and power storage due to their high energy density, good safety characteristics, excellent cycle performance, and wide temperature window. Meanwhile, with the rapid development of electric ships and electric aircraft, various new application scenarios are constantly placing higher demands on battery energy density. Increasing the operating voltage is one of the important ways to improve the energy density of lithium-ion batteries. However, under high voltage, the battery system faces the following challenges: 1) Metal ions in the positive electrode material are more easily dissolved in the electrolyte under high voltage; 2) The electrolyte is more easily oxidized and decomposed on the positive electrode surface; 3) Due to the increased concentration of metal ions dissolved in the electrolyte, they are more likely to deposit on the negative electrode, thereby damaging the solid electrolyte interfacial film. These conditions are exacerbated at high temperatures.

[0003] It is worth noting that the electrolyte, as the medium for lithium-ion transport within the battery and a crucial source of solid electrolyte interfacial film formation, has a key impact on the interface stability and high- and low-temperature performance of lithium-ion batteries. Furthermore, additives, often referred to as the "vitamins" of the electrolyte, can assist in the formation of a solid electrolyte interfacial layer on the surface of the positive or negative electrode during the initial charge-discharge process, thereby suppressing ongoing side reactions between the electrode and electrolyte. This plays a vital role in improving battery internal resistance, extending battery life, and enhancing high- and low-temperature performance. Based on their different functions, electrolyte additives can generally be categorized into film-forming additives, flame-retardant additives, high-temperature additives, stabilizing additives, and high-voltage additives. Since a single additive often cannot simultaneously achieve multiple functions, much current research focuses on developing mixed additives or multifunctional additives to achieve synergistic effects. However, the stability of mixed additives remains questionable, and the development cycle for multifunctional additives is generally long.

[0004] Among numerous additives, 1,3-propenesulfonate lactone (PST), as a sulfonate ester additive, contains unsaturated C=C groups, making it a bifunctional compound that can simultaneously achieve two functions: 1) Excellent film-forming additive: PST exhibits good film-forming capabilities on both the positive and negative electrode sides. The dense solid electrolyte interface film can effectively suppress the co-intercalation of solvent molecules into the electrode material, inhibiting continuous side reactions between the electrode and electrolyte, thereby effectively improving the cycle performance of lithium-ion batteries; 2) Ideal high-temperature electrolyte additive: The solid electrolyte interface film formed with the assistance of PST is relatively stable at high temperatures, effectively suppressing high-temperature gas expansion and capacity decay during high-temperature storage, thus effectively improving high-temperature performance. However, because the formed interface film is not necessarily completely stable and dense, the film-forming quality of different systems is closely related to the PST content. If the PST content is too high, it will affect the rate performance of the battery, potentially affecting lithium-ion migration under high current. Simultaneously, as the temperature decreases, polarization gradually increases, resulting in poorer low-temperature performance when the PST content is too high. In summary, the introduction of PST can effectively improve interfacial film formation and high-temperature performance. However, excessive dosage can affect rate performance and low-temperature performance. Therefore, determining the appropriate PST dosage and achieving accurate detection to obtain the best results is of paramount importance.

[0005] Currently, most research on PST additives focuses on synthesis, electrolyte preparation, and comparing their application effects in different systems. PST is a white solid at room temperature and pressure. Although soluble in organic solvents such as methanol and dichloromethane, current detection methods for PST are limited. Existing technology KR1020180034862A discloses a method for preparing cyclic 1,3-propenylsulfonyl lactone, which uses nuclear magnetic resonance spectroscopy (NMR spectroscopy) to determine the structural composition of 1,3-propenylsulfonyl lactone. This testing process is cumbersome and has high requirements for sample content, specifically high limits of detection and quantitation for the detected components. When the content is too low, this method is difficult to use. Currently, there are no reports on how to detect trace amounts of PST additives in electrolytes, which hinders the development of electrolytes. Given the significant potential of PST additives in improving cycle performance and high-temperature performance, determining the PST additive content in electrolyte components is crucial for the research and design of electrolyte compositions in battery cells, the optimization of electrolyte components, and the analysis of battery failure issues. Therefore, there is an urgent need to develop a high-precision detection method to drive the development and design of high-performance electrolytes through accurate quantification. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing PST detection techniques, such as cumbersome processes, limited methods, and ineffective detection of PST content in electrolytes. This invention provides a high-precision method for detecting 1,3-propenesulfonate lactone (PST) content in electrolytes. This method achieves accurate PST detection with low energy consumption by adjusting the column flow rate and split ratio at a sample injection chamber temperature slightly above the boiling point of PST (257°C). This method has low detection and quantitation limits, is applicable to the measurement of PST content in electrolytes, accurately measures PST content, exhibits good repeatability, and is easy to operate, effectively improving the detection accuracy of PST.

[0007] To achieve the above objectives, the present invention provides a high-precision method for detecting the content of 1,3-propenesulfonate lactone in an electrolyte, comprising:

[0008] 1,3-propenesulfonyl lactone (PST) was dissolved in an organic solvent to prepare a set of PST standard solutions with a concentration gradient; the set of PST standard solutions with a concentration gradient included multiple PST standard solutions with different concentrations.

[0009] A chromatographic column is selected, wherein the stationary phase of the column is 5% phenyl-95% dimethyl polysiloxane, the column length is 25-60m, the inner diameter is 0.25-0.50mm, and the inner coating thickness is 0.25-0.50μm;

[0010] Adjust the gas chromatography-mass spectrometry (GC-MS) test parameters; the chromatographic test parameters are as follows: carrier gas is helium, column flow rate is 1.80-2.00 mL / min, split ratio is 20:1-2:1, injection port temperature is 260℃-280℃, injection volume is 0.5uL-1uL, purge rate is 3mL / min-5mL / min; column temperature program: hold at 100℃-110℃ for 3min-5min, increase temperature at a rate of 5℃-10℃ / min to 200℃-220℃, hold at 2min-3min; the mass spectrometry test parameters are as follows: use an electron ionization source, ion source temperature is 200℃-230℃, interface temperature is 250℃-280℃, solvent delay time is 1.0min-2.0min;

[0011] Each PST standard solution in the PST standard solution group with concentration gradient was detected by a gas chromatography-mass spectrometry system with adjusted parameters. The detection peak area of ​​each PST standard solution was recorded, and a standard curve was determined based on the PST concentration in each PST standard solution and the corresponding detection peak area.

[0012] Select the electrolyte to be tested, pretreat the electrolyte, and use a gas chromatography-mass spectrometry system with adjusted parameters to detect the pretreated electrolyte, obtain the measured peak area, and find the corresponding value in the standard curve based on the measured peak area to obtain the concentration of PST in the electrolyte.

[0013] Preferably, the PST standard solution group includes at least 6 PST standard solutions of different concentrations; the concentration of each PST standard solution in the PST standard solution group is between 0 and 30 mg / L;

[0014] The organic solvent is chromatographically pure dichloromethane.

[0015] More preferably, the concentrations of the PST standard solutions in the PST standard solution group are 0 mg / L, 5 mg / L, 10 mg / L, 15 mg / L, 20 mg / L, 25 mg / L and 30 mg / L, respectively.

[0016] Preferably, determining the standard curve based on the PST concentration and detection peak area in the standard solution specifically involves: determining the standard curve using a standard curve equation; wherein the standard curve equation is: S = kC - b, where S is the detection peak area of ​​PST, C is the PST concentration, k is the slope obtained by linear simulation based on the test results of the standard solution under the current test conditions, b is the peak area when the PST concentration is 0 based on the test results of the standard solution under the current test conditions, and the coefficient of determination R of the standard curve equation under the current test conditions is... 2 ≥0.996.

[0017] Preferably, the method further includes: detecting each PST standard solution in the PST standard solution group with concentration gradient using a gas chromatography-mass spectrometry system with adjusted parameters, recording the detection peak area corresponding to each PST standard solution, and determining the limit of detection and limit of quantitation under the current test conditions based on the PST concentration in each PST standard solution and the corresponding detection peak area; wherein the limit of detection is below 4 mg / L and the limit of quantitation is below 12 mg / L;

[0018] The detection limit is the sample concentration corresponding to a peak height of 3 times the baseline noise standard, i.e., a signal-to-noise ratio of 3:1; the quantitation limit is the sample concentration corresponding to a peak height of 10 times the baseline noise standard, i.e., a signal-to-noise ratio of 10:1.

[0019] More preferably, the detection limit is as low as 0.64 mg / L and the quantitation limit is as low as 1.93 mg / L.

[0020] The pretreatment specifically includes: diluting the electrolyte to be tested with dichloromethane; the content of PST in the diluted electrolyte is greater than or equal to 2.5 mg / L.

[0021] The method involves using a gas chromatography-mass spectrometry (GC-MS) instrument with adjusted parameters to detect the pretreated electrolyte, obtaining the measured peak area, and then using the measured peak area to find the corresponding value in the standard curve to determine the concentration of PST in the electrolyte. Specifically, this includes:

[0022] The pretreated electrolyte was analyzed multiple times using a gas chromatography-mass spectrometry (GC-MS) instrument with adjusted parameters. Multiple detection peak areas were obtained through these multiple analyses. The corresponding PST concentrations in the electrolytes were then determined by searching the standard curve based on the measured peak areas. The average PST concentration in the electrolytes was then calculated as the total PST concentration.

[0023] Preferably, the electrolyte to be tested includes: uncirculated raw electrolyte or aged electrolyte that has undergone any number of cycles.

[0024] Preferably, the split ratio is 20:1-10:1;

[0025] The injection port temperature is 260℃-265℃.

[0026] The high-precision detection method for 1,3-propenesulfonate lactone (PST) in electrolytes provided in this invention employs gas chromatography-mass spectrometry (GC-MS) with optimized process parameters. By limiting the injection port temperature and adjusting the column flow rate and split ratio in the GC process, and by setting the column temperature program, PST can be effectively separated from the electrolyte system, significantly improving the detection accuracy of PST and achieving high-precision detection of trace amounts of PST in the electrolyte system. This method has good repeatability, is simple and rapid to operate, and is suitable for the accurate detection of PST content in various electrolytes. Attached Figure Description

[0027] Figure 1 This is a diagram showing the separation effect of PST in full-spectrum scanning mode in Example 1;

[0028] Figure 2 This is a standard curve showing the relationship between PST concentration and peak area in the standard solution of Example 1.

[0029] Figure 3 This is a standard curve showing the relationship between PST concentration and peak area in the standard solution of Example 2.

[0030] Figure 4This is a standard curve showing the relationship between PST concentration and peak area in the standard solution of Example 3.

[0031] Figure 5 This is a standard curve showing the relationship between PST concentration and peak area in the standard solution of Example 4.

[0032] Figure 6 This is a standard curve showing the relationship between PST concentration and peak area in the standard solution of Example 5.

[0033] Figure 7 This is a standard curve showing the relationship between PST concentration and peak area in the standard solution of Example 6.

[0034] Figure 8 This is a standard curve showing the relationship between PST concentration and peak area in the standard solution of Example 7.

[0035] Figure 9 This is a standard curve showing the relationship between PST concentration and peak area in the standard solution of Example 8.

[0036] Figure 10 This is a standard curve showing the relationship between PST concentration and peak area in the standard solution of Example 9.

[0037] Figure 11 This is a standard curve showing the relationship between PST concentration and peak area in the standard solution of Comparative Example 1.

[0038] Figure 12 This is a standard curve showing the relationship between PST concentration and peak area in the standard solution of Comparative Example 2. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0040] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0041] The high-precision detection method for 1,3-propenesulfonate lactone (PST) in electrolytes provided in this invention addresses the problem that PST, as an additive component in electrolytes, has a low content and is difficult to measure accurately using conventional testing techniques. The applicant has discovered that by limiting the injection port temperature in gas chromatography-mass spectrometry (GC-MS), adjusting the column flow rate and split ratio in the GC process, and setting the column temperature program, PST can be effectively separated from the electrolyte system, while significantly improving the detection accuracy of PST.

[0042] The high-precision detection method for the content of 1,3-propenesulfonate lactone in electrolyte proposed in this invention comprises the following main steps:

[0043] Step 110: Dissolve 1,3-propenesulfonyl lactone (PST) in an organic solvent to prepare a set of PST standard solutions with a concentration gradient; the set of PST standard solutions with a concentration gradient includes multiple PST standard solutions with different concentrations.

[0044] The preferred organic solvent is chromatographically pure dichloromethane.

[0045] The PST standard solution set includes at least 6 different concentrations of PST standard solutions; the concentration of each PST standard solution in the PST standard solution set is between 0 and 30 mg / L; preferably, the concentrations are 0 mg / L, 5 mg / L, 10 mg / L, 15 mg / L, 20 mg / L, 25 mg / L and 30 mg / L.

[0046] Step 120: Select a chromatographic column. The stationary phase of the column is 5% phenyl-95% dimethyl polysiloxane. The column length is 25-60m, the inner diameter is 0.25-0.50mm, and the inner coating thickness is 0.25-0.50μm.

[0047] Step 130: Adjust the gas chromatography-mass spectrometry (GC-MS) test parameters. The chromatographic test parameters are as follows: carrier gas is helium, column flow rate is 1.80-2.00 mL / min, split ratio is 20:1-2:1, injection port temperature is 260℃-280℃, injection volume is 0.5 uL-1 uL, and purge rate is 3 mL / min-5 mL / min. The column temperature program is: hold at 100℃-110℃ for 3 min-5 min, increase the temperature to 200℃-220℃ at a rate of 5℃-10℃ / min, and hold for 2 min-3 min. The mass spectrometry test parameters are as follows: use an electron ionization source, ion source temperature is 200℃-230℃, interface temperature is 250℃-280℃, and solvent delay time is 1.0 min-2.0 min.

[0048] Specifically, this invention sets the injection port temperature to 260℃-280℃, preferably 260℃-265℃, which is only slightly higher than the boiling point of PST (PST boiling point is 257℃). This allows all PST to be physically separated from the electrolyte, meaning that preliminary separation of PST is achieved through precise temperature control to ensure the accuracy of subsequent measurements. Simultaneously, this invention maintains the column flow rate in the chromatographic process conditions between 1.80-2.00 mL / min and limits the split ratio to the range of 20:1-2:1. Combined with the column temperature program settings, this effectively controls the separation of PST from other components. Combined with mass spectrometry, the PST content in the electrolyte system can be accurately measured. Under the above process conditions, the measurement error of PST in the sample can be kept within 10%. By limiting the process parameters of this invention, the PST content in the electrolyte can be accurately tested. This is because the process parameters of this invention can significantly reduce the detection limit and quantitation limit, effectively improving detection accuracy, thereby enabling the detection of trace PST components in the electrolyte system.

[0049] Furthermore, when the split ratio is controlled within the range of 20:1 to 10:1, the accuracy of PST determination in the test sample is very high, with the test error basically controlled within 3.5%. The relative standard deviation of six tests on the test sample is within 0.5%, indicating that the test results have high data concentration and low data dispersion. When the split ratio is 10:1, the sensitivity of this detection method is the highest, with the lowest detection limit of PST reaching 0.64 mg / L and the lowest quantitation limit reaching 1.93 mg / L, and the quantitation error can be controlled within 3.5%. In addition, the split ratio is related to the detection limit and quantitation limit; a suitable split ratio can obtain lower detection and quantitation limits, thereby ensuring the accuracy of the detection results of trace PST in the electrolyte.

[0050] Furthermore, the column flow rate of 1.80-2.00 mL / min in the chromatographic test parameters of this invention can be any value within the above range, such as 1.80 mL / min, 1.85 mL / min, 1.86 mL / min, 1.9 mL / min, 1.95 mL / min, and 2.00 mL / min, but is not limited thereto. When the column flow rate is above 1.86 mL / min, the total amount of PST components passing through the chromatographic column can be sufficiently guaranteed.

[0051] The split ratio in the chromatographic test parameters is 20:1-2:1, which can be any value within the above range, such as 20:1, 18:1, 15:1, 12:1, 10:1, 8:1, 5:1, 2:1, but is not limited to this.

[0052] The injection port temperature of this invention is 260℃-280℃, and can be any value within the above range, such as 260℃, 265℃, 270℃, 275℃, or 280℃. The injection port temperature is crucial for the accurate detection of PST content.

[0053] The column temperature program of this invention is as follows: hold the temperature at 100℃-110℃ for 3-5 minutes, then increase the temperature to 200℃-220℃ at a rate of 5℃-10℃ / min, and hold the temperature for 2-3 minutes. Under the above test conditions, the PST component in the electrolyte can be effectively separated from other components, thereby ensuring accurate detection of its content.

[0054] The mass spectrometry testing parameters of this invention are as follows: the ion source is an electron ionization source, the ion source temperature is 200℃-230℃, the interface temperature is 250℃-280℃, and the solvent delay time is 1.0-2.0 min. To match the chromatographic testing process parameters and thus accurately measure the PST content in the electrolyte system, the ion source temperature and interface temperature are limited in this invention. These can be any values ​​within the above range, but are not limited to them. For example, the ion source temperature can be 200℃, 2210℃, 2220℃, or 230℃, and the interface temperature can be 250℃, 255℃, 260℃, 265℃, 270℃, 275℃, or 280℃. The solvent delay time is 1.0-2.0 min and can be any value within the above range, such as 1.0 min, 1.2 min, 1.4 min, 1.5 min, 1.6 min, 1.8 min, and 2.0 min. By limiting the solvent extension time as described above, this extension can prevent a large amount of solvent gas from adversely affecting the filament. Specifically, premature filament activation can lead to carbon buildup in the ion source, affecting filament lifespan and detection accuracy. Mass spectrometry can be performed in ion monitoring mode with an electron energy of 70 eV.

[0055] Step 140: Detect each PST standard solution in the PST standard solution group with concentration gradient using a gas chromatography-mass spectrometry system with adjusted parameters, record the detection peak area corresponding to each PST standard solution, and determine the standard curve based on the PST concentration in each PST standard solution and the corresponding detection peak area.

[0056] Specifically, this invention simulates the standard curve equation based on the correspondence between the concentration and peak area of ​​multiple PST standard solutions, determines the standard curve, and obtains the detection limit and quantitation limit under the corresponding standard solution test conditions.

[0057] The standard curve equation is: S = kC - b, where S is the detected peak area of PST, C is the PST concentration, k is the slope obtained by analyzing the test results of the standard solution under the current test conditions, b is the peak area when the PST concentration is 0 obtained from the test results of the standard solution under the current test conditions, and the values of k and b are both calculated using the instrument's supporting software based on the test results of the standard solution. For example, it can be simulated using the analysis software GCMSsolution supporting the Shimadzu GC-MS instrument, but it does not exclude using common analysis software in this field as long as it can be obtained by those skilled in the art. The determination coefficient R of the standard curve equation under the current test conditions 2 ≥0.996.

[0058] R 2 represents the coefficient of determination, which measures the proportion of the total variation of the model's explanatory variables. Specifically, it represents the degree of fitting of the standard curve equation to the data. Its value range is from 0 to 1, where:

[0059] When R 2 = 1, it means that the model can perfectly explain all the variations in the data, and all data points fall on the fitted curve.

[0060] When R 2 = 0, it means that the model cannot explain any variation in the data, and the fitted curve has no predictive ability.

[0061] The R of the standard curve equation 2 ≥0.996 indicates that the standard curve equation has a very high degree of fitting, indicating that the error when calculating the PST concentration using this equation is very small, with very high accuracy, and can be used for detecting the content of PST components in the electrolyte to be tested, and the results are very reliable.

[0062] In addition, each PST standard solution in the PST standard solution group with a concentration gradient can also be detected using a gas chromatography - mass spectrometry instrument with adjusted parameters, record the detected peak area corresponding to each PST standard solution, and determine the detection limit and quantification limit under the current test conditions based on the PST concentration and the corresponding detected peak area in each PST standard solution. [[ID=​​​The limit of detection (LOD) is the lowest concentration or amount of analyte that an analytical method can detect. In this example, the LOD is the sample concentration at which the peak height is three times the baseline noise level, i.e., a signal-to-noise ratio of 3:1. In this example, the LOD is below 4 mg / L, for example, 4 mg / L, 3 mg / L, 2 mg / L, 1 mg / L, 0.8 mg / L, 0.7 mg / L, with the lowest being 0.64 mg / L.

[0065] The limit of quantitation (LOQ) is the lowest concentration or amount of analyte that an analytical method can quantify. LOQ is typically determined using a method similar to the limit of detection (LOD), but with a higher signal-to-noise ratio (SNR) (usually 10). This means that at the LOQ, the analytical signal should be 10 times the background noise to ensure accurate quantification. In this example, LOQ refers to the sample concentration at which the peak height is 10 times the baseline noise standard, i.e., a SNR of 10:1. In this example, LOQ is below 12 mg / L, for example, 12 mg / L, 10 mg / L, 8 mg / L, 6 mg / L, 5 mg / L, 4 mg / L, 3 mg / L, 2 mg / L, with a minimum of 1.93 mg / L.

[0066] As can be seen, due to the use of the chromatographic mass spectrometry process parameters of this invention, the detection limit and quantitation limit of PST of this invention are significantly reduced, which is something that existing detection technologies cannot detect.

[0067] Step 150: Select the electrolyte to be tested, pretreat the electrolyte, and use a gas chromatograph-mass spectrometer with adjusted parameters to detect the pretreated electrolyte, obtain the measured peak area, and find the corresponding value in the standard curve based on the measured peak area to obtain the concentration of PST in the electrolyte.

[0068] The pretreatment specifically includes: diluting the electrolyte to be tested with dichloromethane; the content of PST in the diluted electrolyte is greater than or equal to 2.5 mg / L.

[0069] Pretreatment to dilute the electrolyte has several main purposes:

[0070] 1. Increased volatility: Dichloromethane is a highly volatile organic solvent that can help increase the overall volatility of the sample to be tested, thereby improving the efficiency of evaporation and separation in GC-MS.

[0071] 2. Reduce sample concentration: The concentration of components in the electrolyte may be high, and direct injection may cause column overload, poor separation, and signal saturation of the mass spectrometer detector. Diluting the sample can reduce the concentration, prevent the above problems, and improve the accuracy and precision of detection.

[0072] 3. Improved solubility: Some components in the electrolyte may be difficult to analyze directly in a chromatography-mass spectrometer. Dichloromethane can effectively dissolve many organic compounds, ensuring that the sample is in a homogeneous solution state upon injection, thereby improving the reproducibility and accuracy of the analysis.

[0073] 4. Reduce matrix effects: The electrolyte may contain high-boiling-point or non-volatile impurities, which can interfere with the chromatographic column and mass spectrometer. Dilution can reduce the concentration of these impurities, thus minimizing their negative impact on analysis.

[0074] Therefore, in this invention, by diluting the electrolyte to be tested with dichloromethane, the volatility of the sample can be increased, the sample concentration can be reduced, the solubility can be increased, the matrix effect can be reduced, and the effect and accuracy of chromatography-mass spectrometry analysis can be improved.

[0075] This invention pretreatment of the electrolyte to be tested involves diluting the electrolyte with dichloromethane. If the PST content after dilution is above the detection limit and quantitation limit of this invention, it can be effectively detected using the method of this invention. According to the detection results of embodiments of this invention, when the PST content in the diluted electrolyte is greater than or equal to 2.5 mg / L, the PST content can be accurately determined. The actual operation process may include, but is not limited to, the following: diluting the unknown electrolyte to be tested with different amounts of dichloromethane, such as 0 times, 10 times, 50 times, 100 times, 200 times, 300 times, 500 times, 600 times, 800 times, 1000 times, etc., and then testing according to the test process conditions, taking multiple sets of parallel test results that are the same or similar as the measurement results. If all the above results are different, it indicates that the PST content in the electrolyte is too low or that the component is absent. The above are just examples; in actual operation, the dilution ratio, etc., can be adjusted according to the situation.

[0076] Furthermore, averaging multiple measurements can improve the accuracy of the results. A gas chromatography-mass spectrometry (GC-MS) system with adjusted parameters can be used to perform multiple measurements on the pretreated electrolyte, obtaining multiple peak areas. These peak areas are then compared against a standard curve to determine the PST concentration in each electrolyte. Finally, the average PST concentration in the electrolyte is calculated.

[0077] By conducting multiple parallel tests, errors caused by accidental factors during the measurement process can be effectively reduced, thus maximizing the accuracy of the test results.

[0078] The detection method of this embodiment can be used to detect electrolytes including uncirculated raw electrolytes and aged electrolytes after any number of cycles. Therefore, this invention is applicable to the research and development, design, optimization, and adjustment of battery system electrolytes, as well as the analysis of battery operation processes. In particular, for battery failure analysis, by comparing the changes in PST content in electrolytes after different number of cycles and / or under different states such as charge and discharge after different number of cycles, it helps to explain the process and mechanism of PST-assisted film formation.

[0079] The present invention provides a high-precision detection method for 1,3-propenesulfonate lactone (PST) content in electrolyte. This method employs gas chromatography-mass spectrometry (GC-MS) with optimized process parameters. By limiting the injection port temperature and adjusting the column flow rate and split ratio in the gas chromatography process, combined with the setting of the column temperature program, the method can effectively separate PST from the electrolyte system and significantly improve the detection accuracy of PST, thus achieving high-precision detection of trace amounts of PST in the electrolyte system.

[0080] This invention also validated the detection limit, quantitation limit, and testing error of the test method. The results showed that the PST concentration and peak area of ​​the test curve had a good linear relationship, and the coefficient of determination R0 was [value missing]. 2 (The accuracy parameter of the standard curve is represented by the number 1, which indicates a perfect match, and the closer it is to 1, the higher the accuracy.) It can reach 0.996 and above.

[0081] The method of the present invention has good repeatability, is simple and fast to operate, and is suitable for the accurate detection of PST content in electrolytes.

[0082] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The following embodiments use a GCMS-QP2020NX gas chromatography-mass spectrometry system, including an autosampler and a GCMS solution workstation. The chromatographic columns used are all DB-5MS 30m×0.25mm×0.25μm (Agile).

[0083] Example 1

[0084] (1) Prepare standard solutions by dissolving PST in chromatographically pure dichloromethane reagent to prepare PST standard solutions with concentrations of 0, 5 mg / L, 10 mg / L, 15 mg / L, 20 mg / L, 25 mg / L and 30 mg / L respectively.

[0085] (2) Prepare the electrolyte to be tested. Weigh 0.1g of the lithium-ion battery electrolyte to be tested, in which the PST content is known to be 0.25%. Add chromatographic grade dichloromethane reagent to dilute it so that the PST content is 2.5mg / L. Shake well and test.

[0086] (3) Adjust the test parameters of the gas chromatography-mass spectrometry (GC-MS) instrument. The carrier gas is helium, the column flow rate is 1.86 mL / min, the split ratio is 20:1, the inlet temperature is 260 °C, the injection volume is 0.5 μL, the purge is 3 mL / min, and the column temperature program is as follows: hold at 110 °C for 3 min, then increase the temperature to 220 °C at a rate of 10 °C / min and hold for 2 min. The mass spectrometry conditions are as follows: the ion source uses an electron ionization source, the electron energy is 70 eV, the ion source temperature is 230 °C, the interface temperature is 260 °C, the solvent delay time is 1.4 min, and the ion detection mass-to-charge ratio range is set to 35.0 - 450.0.

[0087] First, identify the qualitative and quantitative ions corresponding to PST Figure 1 For the separation effect of PST from other organic compounds in the electrolyte under the full-spectrum scanning mode. In the figure, 1 is methyl trifluoroethyl carbonate and 2 is fluorinated ethylene carbonate. It can be seen that the peak shape of PST is symmetric and sharp, indicating that good separation can be achieved under these test conditions. The quantitative and qualitative selected ions of PST are shown in Table 1, and the quantitative and qualitative ions in Table 1 have good sensitivity and response. m / z represents the ratio of mass to charge. In subsequent examples, the detection of PST is determined according to the following mass-to-charge ratio parameters.

[0088] Table 1 Quantitative and Qualitative Selected Ions of PST

[0089] Compound Name Qualitative ion m / z Quantitative ion m / z PST 43 / 65 66 <0OO0232>(4) Test the standard solutions, record the instrument response values corresponding to each standard solution, that is, the peak area (S), analyze the data using the supporting software GCMSsolution of this equipment, and draw the standard curve of PST and the peak area in the standard solutions to obtain Figure 2 , and the linear equation of the standard curve of PST is S = 1315.521×C - 459.5357, R 2 = 0.9994, where S is the area of the detection peak of PST, C is the concentration of PST in the electrolyte, with the unit of mg / L, R is the coefficient of determination, and the closer the value of R 2 is to 1, the better the linear correlation of this equation.

[0091] (5) Determine the detection limit and quantification limit. According to the detection requirements of chromatography-mass spectrometry, the detection limit is the sample concentration when the generated signal (peak height) is 3 times the standard deviation of the baseline noise, that is, the concentration corresponding to a signal-to-noise ratio of 3:1, and the quantification limit is the sample concentration when the generated signal (peak height) is 10 times the standard deviation of the baseline noise, that is, the concentration corresponding to a signal-to-noise ratio of 10:1. Therefore, the concentration of PST (i.e., the detection limit) is 0.81 mg / L at a signal-to-noise ratio of 3:1, and the concentration of PST (i.e., the quantification limit) is 2.46 mg / L at a signal-to-noise ratio of 10:1;

[0092] (6) Perform a quantitative test on the electrolyte to be measured, record the peak area, and analyze the sample by parallel injection six times. According to the equation obtained in step (4), calculate the content of PST in the electrolyte sample. The specific experimental results are shown in Table 2. It should be noted here that in Example 1, six peak areas are listed, and the concentration of PST is calculated according to the corresponding formula. The same applies to other examples.

[0093] Table 2 Test results of PST in electrolyte samples

[0094]

[0095] The concentration of PST in the electrolyte obtained by the test method in Example 1 is 2.57 mg / L, which is very close to its actual content of 2.5 mg / L. The relative deviation of the measurement result is only 0.20%, and the overall test error is only 2.80%. It can be seen that the accuracy of detection using the process parameters in Example 1 is very high, which has practical guiding significance for electrolyte analysis.

[0096] Example 2

[0097] (1) The method for preparing the standard solution is the same as that in Example 1;

[0098] (2) Prepare the electrolyte to be measured. Weigh 0.1 g of the lithium-ion battery electrolyte to be measured, in which the known content of PST is 0.75%. Add chromatographically pure dichloromethane reagent for dilution so that the content of PST in it is 7.5 mg / L. Shake well for later measurement;

[0099] (3) Adjust the test parameters of the gas chromatography-mass spectrometry instrument. The carrier gas is helium, the column flow rate is 1.86 mL / min, the split ratio is 10:1, the injection port temperature is 260 °C, the injection volume is 0.5 μL, the purge is 3 mL / min, and the column temperature program is: keep the temperature constant at 110 °C for 3 min, increase the temperature at a rate of 10 °C / min to 220 °C, and keep the temperature constant for 2 min. The mass spectrometry conditions are: the ion source uses an electron ionization source, the electron energy is 70 eV, the ion source temperature is 230 °C, the interface temperature is 260 °C, the solvent delay time is 1.4 min, and the selected ion monitoring mode is used. The selected ions for PST quantification and qualitative analysis are the same as in Table 1;

[0100] (4) Test the standard solution, record the instrument response values corresponding to each standard solution, that is, the peak area (S). Use the equipment's supporting software GCMSsolution to analyze the data and draw the standard curve of PST and peak area in the standard solution, and obtain Figure 3 , the linear equation of the standard curve of PST is S = 2769.914×C - 1768.857, R 2= 0.9987, where S is the area of ​​the PST detection peak, C is the PST concentration in the electrolyte (mg / L), and R is the coefficient of determination. 2 The closer the value is to 1, the better the linear correlation of the equation;

[0101] (5) Determine the detection limit and quantitation limit. According to the detection requirements of chromatographic mass spectrometry, the detection limit is the sample concentration at which the generated signal (peak height) is 3 times the standard deviation of the baseline noise, that is, the concentration at a signal-to-noise ratio of 3:1. The quantitation limit is the sample concentration at which the generated signal (peak height) is 10 times the standard deviation of the baseline noise, that is, the concentration at a signal-to-noise ratio of 10:1. Therefore, the detection limit of PST under the test conditions is 0.64 mg / L at a signal-to-noise ratio of 3:1, and the quantitation limit of PST under the test conditions is 1.93 mg / L at a signal-to-noise ratio of 10:1.

[0102] (6) Quantitatively test the electrolyte to be tested, record the peak area, perform parallel injection analysis 6 times, and calculate the concentration of PST in the electrolyte sample according to the equation obtained in step (4). The specific experimental results are shown in Table 3.

[0103] Table 3. Test results of PST in electrolyte samples

[0104]

[0105] Compared with Example 1, the column flow rate remained unchanged, the split ratio decreased, the amount of sample entering the chromatographic column increased, and the results of the 6 tests were relatively concentrated, with the relative standard deviation increasing by 0.08% and the test error increasing by 0.27%.

[0106] Example 3

[0107] (1) The method for preparing the standard solution is the same as in Example 1;

[0108] (2) Prepare the electrolyte to be tested. Weigh 0.1g of the lithium-ion battery electrolyte to be tested, in which the PST content is known to be 1.25%. Add chromatographic grade dichloromethane reagent to dilute it so that the PST content is 12.5mg / L. Shake well and test.

[0109] (3) Adjust the test parameters of the gas chromatography-mass spectrometry (GC-MS) instrument, where the carrier gas is helium, the column flow rate is 1.86 mL / min, the split ratio is 5:1, the injection port temperature is 260℃, the injection volume is 0.5 μL, the purge rate is 3 mL / min, and the column temperature program is: hold at 110℃ for 3 min, increase the temperature to 220℃ at a rate of 10℃ / min, and hold at 2 min. The mass spectrometry conditions are: use an electron ionization source with an electron energy of 70 eV, an ion source temperature of 230℃, an interface temperature of 260℃, a solvent delay time of 1.4 min, select ion monitoring mode, and select the same ions for PST quantitative and qualitative analysis as in Table 1;

[0110] (4) Test the standard solutions, record the instrument response values corresponding to each standard solution, i.e., the peak area (S), analyze the data using the supporting software GCMSsolution of this device, draw the standard curve of PST and peak area in the standard solutions, and obtain Figure 4 , the linear equation of the standard curve of PST is S = 5706.371×C - 4198.571, R 2 = 0.9977, where S is the area of the PST detection peak, C is the concentration of PST in the electrolyte, with the unit of mg / L, R is the coefficient of determination, and the closer the value of R 2 is to 1, the better the linear correlation of this equation;

[0111] (5) Determine the detection limit and quantification limit. According to the detection requirements of chromatography - mass spectrometry, the detection limit is the sample concentration when the generated signal (peak height) is 3 times the standard deviation of the baseline noise, that is, the concentration corresponding to a signal - to - noise ratio of 3:1, and the quantification limit is the sample concentration when the generated signal (peak height) is 10 times the standard deviation of the baseline noise, that is, the concentration corresponding to a signal - to - noise ratio of 10:1. Therefore, the detection limit of PST under this test condition is read as 0.75 mg / L at a signal - to - noise ratio of 3:1, and the quantification limit of PST under this condition is read as 2.29 mg / L at a signal - to - noise ratio of 10:1;

[0112] (6) Conduct a quantitative test on the electrolyte to be measured, record the peak area, perform parallel injection analysis 6 times, and calculate the concentration of PST in the electrolyte sample according to the equation obtained in step (4). The specific experimental results are shown in Table 4.

[0113] Table 4 Test results of PST in electrolyte samples

[0114]

[0115] Compared with Example 1, the column flow rate remains unchanged, the split ratio is further reduced, and the amount of sample entering the chromatographic column is more, resulting in a relatively high column pressure and a decrease in detection accuracy. Among them, the relative standard deviation increases by 0.45%, and the test error increases by 3.36%.

[0116] Example 4

[0117] (1) The method for preparing the standard solution is the same as that in Example 1;

[0118] (2) Prepare the electrolyte to be measured. Weigh 0.1 g of the electrolyte of the lithium - ion battery to be measured, where the PST content is known to be 1.75%, add chromatographically pure dichloromethane reagent for dilution so that the PST content is 17.5 mg / L, shake well for later measurement;

[0119] (3) Adjust the test parameters of the gas chromatography - mass spectrometry (GC - MS). The carrier gas is helium, the column flow rate is 1.86 mL / min, the split ratio is 2:1, the inlet temperature is 260 °C, the injection volume is 0.5 μL, the purge rate is 3 mL / min, and the column temperature program is as follows: hold at 110 °C for 3 min, then increase the temperature to 220 °C at a rate of 10 °C / min and hold for 2 min. The mass spectrometry conditions are: the ion source uses an electron ionization source, the electron energy is 70 eV, the ion source temperature is 230 °C, the interface temperature is 260 °C, the solvent delay time is 2.0 min, and the selected ion monitoring mode is used. The quantitative and qualitative selected ions for PST are the same as those in Table 1.

[0120] (4) Test the standard solutions, record the instrument response values corresponding to each standard solution, that is, the peak area (S), analyze the data using the software GCMSsolution supporting this equipment, and plot the standard curve of PST and peak area in the standard solutions to obtain Figure 5 , and the linear equation of the standard curve of PST is S = 14777.04×C - 8616.821, R 2 = 0.9986, where S is the area of the PST detection peak, C is the concentration of PST in the electrolyte, with the unit of mg / L, and R is the coefficient of determination. The closer the value of R 2 is to 1, the better the linear correlation of this equation;

[0121] (5) Determine the detection limit and quantification limit. According to the detection requirements of chromatography and mass spectrometry, the detection limit is the sample concentration when the signal (peak height) is 3 times the standard deviation of the baseline noise, that is, the concentration corresponding to a signal - to - noise ratio of 3:1, and the quantification limit is the sample concentration when the signal (peak height) is 10 times the standard deviation of the baseline noise, that is, the concentration corresponding to a signal - to - noise ratio of 10:1. Therefore, at a signal - to - noise ratio of 3:1, the detection limit of PST under this test condition is read as 0.69 mg / L, and at a signal - to - noise ratio of 10:1, the quantification limit of PST under this condition is read as 2.08 mg / L;

[0122] (6) Conduct a quantitative test on the electrolyte to be tested, record the peak area, and perform parallel injection analysis 6 times. According to the equation obtained in step (4), calculate the concentration of PST in the electrolyte sample. The specific experimental results are shown in Table 5.

[0123] Table 5 Test results of PST in electrolyte samples

[0124]

[0125] Compared with Example 1, in this example, the column flow rate remains unchanged, the split ratio continues to decrease, the amount of sample entering the chromatographic column further increases, the column pressure further increases, resulting in a decrease in separation efficiency and a corresponding reduction in the detection accuracy of PST. The relative standard deviation increases by 0.61%, and the test error increases by 4.8%.

[0126] Example 5

[0127] (1) The method for preparing the standard solution is the same as that in Example 1;

[0128] (2) Prepare the electrolyte to be tested. Weigh 0.1 g of the lithium-ion battery electrolyte to be tested, in which the PST content is known to be 2.25%. Add chromatographically pure dichloromethane reagent for dilution so that the PST content is 22.5 mg / L. Shake well for testing;

[0129] (3) Adjust the test parameters of the gas chromatography-mass spectrometry instrument. The carrier gas is helium, the column flow rate is 2.0 mL / min, the split ratio is 20:1, the injection port temperature is 260 °C, the injection volume is 0.5 μL, the purge is 3 mL / min, and the column temperature program is: hold at 110 °C for 3 min, increase the temperature at a rate of 10 °C / min to 220 °C, and hold for 2 min. The mass spectrometry conditions are: the ion source uses an electron ionization source, the electron energy is 70 eV, the ion source temperature is 230 °C, the interface temperature is 260 °C, the solvent delay time is 1.4 min, and the selected ion monitoring mode is used. The selected ions for PST quantification and qualitative analysis are the same as in Table 1;

[0130] (4) Test the standard solution, record the instrument response values corresponding to each standard solution, that is, the peak area (S). Use the supporting software GCMSsolution of this equipment to analyze the data, draw the standard curve of PST and the peak area in the standard solution, and obtain Figure 6 , and the linear equation of the PST standard curve is S = 2251.841×C – 630.53, R 2 = 0.9963, where S is the area of the PST detection peak, C is the concentration, with the unit of mg / L, and R is the coefficient of determination. The closer the value of R 2 is to 1, the better the linear correlation of this equation;

[0131] (5) Determine the detection limit and quantification limit. According to the detection requirements of chromatography-mass spectrometry, the detection limit is the sample concentration when the signal (peak height) is 3 times the standard deviation of the baseline noise, that is, the concentration corresponding to a signal-to-noise ratio of 3:1. The quantification limit is the sample concentration when the signal (peak height) is 10 times the standard deviation of the baseline noise, that is, the concentration corresponding to a signal-to-noise ratio of 10:1. Therefore, at a signal-to-noise ratio of 3:1, the detection limit of PST under this test condition is read as 0.77 mg / L, and at a signal-to-noise ratio of 10:1, the quantification limit of PST under this condition is read as 2.20 mg / L;

[0132] (6) Conduct a quantitative test on the electrolyte to be tested, record the peak area, and perform parallel injection analysis 6 times. According to the equation obtained in step (4), calculate the concentration of PST in the electrolyte sample. The specific experimental results are shown in Table 6.

[0133] Test Results of PST in the Electrolyte Samples in Table 6

[0134]

[0135] Compared with Example 1, the split ratio remains unchanged, but the column flow rate increases by 0.14 mg / L. The amount of sample entering the chromatographic column increases, and the detection accuracy is relatively high. Among them, the relative standard deviation increases by 0.25%, and the test error increases by 0.18%.

[0136] Example 6

[0137] (1) The method for preparing the standard solution is the same as that in Example 1;

[0138] (2) Prepare the electrolyte to be tested. Weigh 0.1 g of the lithium-ion battery electrolyte to be tested, the PST content of which is known to be 2.75%. Add chromatographically pure dichloromethane reagent for dilution so that the PST content is 27.5 mg / L. Shake well and wait for testing;

[0139] (3) Adjust the test parameters of the gas chromatography-mass spectrometry instrument. The carrier gas is helium, the column flow rate is 2.0 mL / min, the split ratio is 10:1, the inlet temperature is 260 °C, the injection volume is 0.5 μL, the purge is 3 mL / min, and the column temperature program is: keep the temperature constant at 110 °C for 3 min, increase the temperature at a rate of 10 °C / min to 220 °C, and keep the temperature constant for 2 min. The mass spectrometry conditions are: the ion source uses an electron ionization source, the electron energy is 70 eV, the ion source temperature is 230 °C, the interface temperature is 260 °C, the solvent delay time is 1.4 min, and the selected ion monitoring mode is used. The selected ions for PST quantification and qualitative analysis are the same as those in Table 1;

[0140] (4) Test the standard solution and record the instrument response values corresponding to each standard solution, that is, the peak area (S). Use the supporting software GCMSsolution of this device to analyze the data and draw the standard curve of PST and the peak area in the standard solution, and obtain Figure 7 , the linear equation of the standard curve of PST is S = 4063.258×C – 2351.268, R 2 = 0.9992, where S is the area of the PST detection peak, C is the concentration of PST in the electrolyte, the unit is mg / L, R is the coefficient of determination, and the closer the value of R 2 is to 1, the better the linear correlation of this equation;

[0141] (5) Determine the detection limit and quantitation limit. According to the detection requirements of chromatographic mass spectrometry, the detection limit is the sample concentration at which the generated signal (peak height) is 3 times the standard deviation of the baseline noise, that is, the concentration at a signal-to-noise ratio of 3:1. The quantitation limit is the sample concentration at which the generated signal (peak height) is 10 times the standard deviation of the baseline noise, that is, the concentration at a signal-to-noise ratio of 10:1. Therefore, the detection limit of PST under the test conditions is 0.66 mg / L at a signal-to-noise ratio of 3:1, and the quantitation limit of PST under the test conditions is 2.04 mg / L at a signal-to-noise ratio of 10:1.

[0142] (6) Perform quantitative testing on the electrolyte to be tested, record the peak area, perform parallel injection analysis 6 times, and calculate the concentration of PST in the electrolyte sample according to the equation obtained in step (4). The specific experimental results are shown in Table 7.

[0143] Table 7. Test results of PST in electrolyte samples

[0144]

[0145] Compared to Example 1, the increased column flow rate coupled with a decreased split ratio resulted in a better balance of sample volume entering the column. Compared to Example 1, the relative standard deviation increased by 0.07%, and the test error increased by 0.69%. Compared to Example 5, the same column flow rate was used, but the split ratio decreased, resulting in a decrease in the relative standard deviation of 0.18% and an increase in the test error of 0.51%. This indicates that maintaining an appropriate split ratio while increasing the column flow rate can, to some extent, prevent column overload, ensure good separation of PST components, and achieve relatively high detection accuracy.

[0146] Example 7

[0147] (1) The method for preparing the standard solution is the same as in Example 1;

[0148] (2) Prepare the electrolyte to be tested. Weigh 0.1g of the lithium-ion battery electrolyte to be tested, in which the PST content is known to be 1.25%. Add chromatographic grade dichloromethane reagent to dilute it so that the PST content is 12.5mg / L. Shake well and test.

[0149] (3) Adjust the test parameters of the gas chromatography - mass spectrometry (GC - MS). The carrier gas is helium, the column flow rate is 2.0 mL / min, the split ratio is 5:1, the inlet temperature is 260 °C, the injection volume is 0.5 μL, the purge rate is 3 mL / min, and the column temperature program is as follows: hold at 110 °C for 3 min, then increase the temperature to 220 °C at a rate of 10 °C / min and hold for 2 min. The mass spectrometry conditions are: the ion source uses an electron ionization source, the electron energy is 70 eV, the ion source temperature is 230 °C, the interface temperature is 260 °C, the solvent delay time is 1.4 min, and the selected ion monitoring mode is used. The quantitative and qualitative selected ions for PST are the same as in Table 1;

[0150] (4) Test the standard solutions, record the instrument response values corresponding to each standard solution, that is, the peak area (S). Use the software GCMSsolution supporting this equipment to analyze the data, draw the standard curve of PST and the peak area in the standard solutions, and obtain Figure 8 , and the linear equation of the standard curve of PST is S = 8797.328×C – 3526.158, R 2 = 0.9978, where S is the area of the PST detection peak, C is the concentration of PST in the electrolyte, with the unit of mg / L, and R is the coefficient of determination. The closer the value of R 2 is to 1, the better the linear correlation of this equation;

[0151] (5) Determine the detection limit and quantification limit. According to the detection requirements of chromatography - mass spectrometry, the detection limit is the sample concentration when the signal (peak height) is 3 times the standard deviation of the baseline noise, that is, the concentration corresponding to a signal - to - noise ratio of 3:1. The quantification limit is the sample concentration when the signal (peak height) is 10 times the standard deviation of the baseline noise, that is, the concentration corresponding to a signal - to - noise ratio of 10:1. Therefore, at a signal - to - noise ratio of 3:1, the detection limit of PST under this test condition is read as 2.54 mg / L, and at a signal - to - noise ratio of 10:1, the quantification limit of PST under this condition is read as 8.38 mg / L;

[0152] (6) Conduct a quantitative test on the electrolyte to be tested, record the peak area, and perform parallel injection analysis 6 times. According to the equation obtained in step (4), calculate the concentration of PST in the electrolyte sample. The specific experimental results are shown in Table 8.

[0153] Table 8 Test results of PST in electrolyte samples

[0154]

[0155] Compared with Example 1, while the column flow rate increases, the split ratio continuously decreases, the amount of sample entering the chromatographic column increases, the column pressure increases, and the detection accuracy of PST decreases. Compared with Example 1, the relative standard deviation increases by 0.36%, and the test error increases by 3.68%. Compared with Example 6, the relative standard deviation increases by 0.29%, and the test error increases by 2.99%. This indicates that while the column flow rate increases but the split ratio is too small, it will still cause a certain degree of decline in the detection accuracy, which also shows that the split ratio has a greater impact on the detection accuracy.

[0156] Example 8

[0157] (1) The method for preparing the standard solution is the same as in Example 1;

[0158] (2) Prepare the electrolyte to be tested. Weigh 0.1 g of the lithium-ion battery electrolyte to be tested, in which the PST content is known to be 1.25%. Add chromatographically pure dichloromethane reagent for dilution so that the PST content is 12.5 mg / L, shake well and wait for testing;

[0159] (3) Adjust the test parameters of the gas chromatography-mass spectrometry instrument. The carrier gas is helium, the column flow rate is 2.0 mL / min, the split ratio is 2:1, the inlet temperature is 260 °C, the injection volume is 0.5 μL, the purge is 3 mL / min, and the column temperature program is: keep the temperature constant at 110 °C for 3 min, increase the temperature at a rate of 10 °C / min to 220 °C, and keep the temperature constant for 2 min. The mass spectrometry conditions are: the ion source uses an electron ionization source, the ion source temperature is 230 °C, the interface temperature is 260 °C, the solvent delay time is 1.4 min, and the selected ion monitoring mode is used. The selected ions for PST quantification and qualitative analysis are the same as in Table 1;

[0160] (4) Test the standard solution, record the instrument response values corresponding to each standard solution, that is, the peak area (S), use the supporting software GCMSsolution of this equipment to analyze the data, and draw the standard curve of PST and the peak area in the standard solution to obtain Figure 9 , the linear equation of the standard curve of PST is S = 26157.565×C – 3125.632, R 2 = 0.9980, where S is the area of the PST detection peak, C is the concentration of PST in the electrolyte, with the unit of mg / L, and R is the coefficient of determination. The closer the value of R 2 is to 1, the better the linear correlation of this equation;

[0161] (5) Determine the detection limit and quantitation limit. According to the detection requirements of chromatographic mass spectrometry, the detection limit is the sample concentration at which the generated signal (peak height) is 3 times the standard deviation of the baseline noise, that is, the concentration at a signal-to-noise ratio of 3:1. The quantitation limit is the sample concentration at which the generated signal (peak height) is 10 times the standard deviation of the baseline noise, that is, the concentration at a signal-to-noise ratio of 10:1. Therefore, the detection limit of PST under the test conditions is 3.52 mg / L at a signal-to-noise ratio of 3:1, and the quantitation limit of PST under the test conditions is 11.06 mg / L at a signal-to-noise ratio of 10:1.

[0162] (6) Perform quantitative testing on the electrolyte to be tested, record the peak area, perform parallel injection analysis 6 times, and calculate the concentration of PST in the electrolyte sample according to the equation obtained in step (4). The specific experimental results are shown in Table 9.

[0163] Table 9. Test results of PST in electrolyte samples

[0164]

[0165] Compared to Example 1, when the column flow rate increases while the split ratio continues to decrease, the amount of sample entering the column increases, leading to a further increase in column pressure and consequently a decrease in the detection accuracy of PST. Compared to Example 1, the relative standard deviation increased by 1.04%, and the test error increased by 4.48%. Compared to Example 6, the relative standard deviation increased by 0.97%, and the test error increased by 3.79%. Compared to Example 7, the relative standard deviation increased by 0.68%, and the test error increased by 0.80%. This indicates that a smaller split ratio leads to decreased detection accuracy, manifested as greater data dispersion and increased test error.

[0166] In Examples 1-8 of this invention, the column flow rate was 1.86 mL / min and the split ratio was 20:1 in Example 1; 10:1 in Example 2; 5:1 in Example 3; 2:1 in Example 4; 2:1 in Example 5; 2:2.0 mL / min and 20:1 in Example 6; 2:1 in Example 7; 5:1 in Example 8; and 2:1 in Example 9. It can be seen that the column flow rate was the same in Examples 1-4, but the split ratio decreased sequentially; the column flow rate was the same in Examples 5-8, but the split ratio decreased sequentially; and the column flow rate of Examples 5-8 was higher than that of Examples 1-4.

[0167] In the test results of Examples 1-8 of the present invention, the test errors were all less than 10%. Specifically, the test errors in Examples 1 and 5 were less than 3%, specifically 2.80% and 2.98% respectively; the test errors in Examples 2 and 6 were less than 5%, specifically 3.07% and 3.49% respectively; and the test errors in Examples 3, 4, 7, and 8 were all less than 10%, specifically 6.16%, 7.60%, 6.48%, and 7.28% respectively. The test error results show that when the split ratio is higher than 10:1, the detection accuracy obtained by the test method of the present invention is higher. When the split ratio is lower than 10:1, the measurement error increases. Under the same split ratio, as shown in the comparative data of Examples 1 and 5, Examples 2 and 6, and Examples 3 and 7, the test error is relatively smaller when the column flow rate is lower. Therefore, both the column flow rate and the split ratio affect the test accuracy. In summary, better measurement accuracy can be obtained when the column flow rate is lower and the split ratio is moderate.

[0168] Furthermore, the relative standard deviation results show that the lowest relative standard deviation was 0.20% in Example 1, followed by 0.28% and 0.27% in Examples 2 and 6, respectively. Although the column flow rates differed in Examples 2 and 6, the split ratio was 10:1 in both, indicating good data consistency across multiple measurements when the split ratio was appropriate. Additionally, the test errors in Examples 2 and 6 were both less than 5%, further demonstrating that the overall deviation of the test data results was slight when the split ratio was appropriate.

[0169] Example 9

[0170] (1) The method for preparing the standard solution is the same as in Example 1;

[0171] (2) Prepare the electrolyte to be tested. Weigh 0.1g of the lithium-ion battery electrolyte to be tested, in which the PST content is known to be 0.25%. Add chromatographic grade dichloromethane reagent to dilute it so that the PST content is 2.5mg / L. Shake well and test.

[0172] (3) Adjust the test parameters of the gas chromatography-mass spectrometry (GC-MS) instrument, where the carrier gas is helium, the column flow rate is 1.86 mL / min, the split ratio is 20:1, the injection port temperature is 280℃, the injection volume is 0.5 μL, the purge rate is 3 mL / min, and the column temperature program is: hold at 110℃ for 3 min, increase the temperature to 220℃ at a rate of 10℃ / min, and hold at 2 min. The mass spectrometry conditions are: use an electron ionization source with an electron energy of 70 eV, an ion source temperature of 230℃, an interface temperature of 260℃, a solvent delay time of 1.4 min, select ion monitoring mode, and select the same ions for PST quantitative and qualitative analysis as in Table 1;

[0173] (4) Test the standard solutions, record the instrument response values corresponding to each standard solution, i.e., the peak area (S), analyze the data using the software GCMSsolution supporting this device, draw the standard curve of PST and the peak area in the standard solutions, and obtain Figure 10 , the linear equation of the standard curve of PST is S = 1768.986×C – 356.765, R 2 = 0.9989, where S is the area of the PST detection peak, C is the concentration of PST in the electrolyte, with the unit of mg / L, and R is the coefficient of determination. The closer the value of R 2 is to 1, the better the linear correlation of this equation;

[0174] (5) Determine the detection limit and quantification limit. According to the detection requirements of chromatography - mass spectrometry, the detection limit is the sample concentration when the generated signal (peak height) is 3 times the standard deviation of the baseline noise, that is, the concentration corresponding to a signal - to - noise ratio of 3:1, and the quantification limit is the sample concentration when the generated signal (peak height) is 10 times the standard deviation of the baseline noise, that is, the concentration corresponding to a signal - to - noise ratio of 10:1. Therefore, at a signal - to - noise ratio of 3:1, the detection limit of PST under this test condition is read as 0.75 mg / L, and at a signal - to - noise ratio of 10:1, the quantification limit of PST under this condition is read as 2.04 mg / L;

[0175] (6) Conduct a quantitative test on the electrolyte to be tested, record the peak area, perform parallel injection analysis 6 times, and calculate the concentration of PST in the electrolyte sample according to the equation obtained in step (4). The specific experimental results are shown in Table 10.

[0176] Table 10 Test results of PST in electrolyte samples [[ID=十六]] [[ID=十七]]

[0177] [[ID=十八]] [[ID=十九]] [[ID=二十]]

[0178] [[ID=二十一]]Compared with Example 1, in Example 9, the column flow rate remains unchanged, the split ratio remains unchanged, only the inlet temperature is increased from 260 °C to 280 °C. The 6 - test results are relatively concentrated. Among them, the relative standard deviation increases by 0.09%, and the test error increases by 0.80%. The change in the relative standard deviation is not significant, while the test error increases slightly but is still within 5%, indicating that the test accuracy is also relatively high when the inlet temperature is 280 °C. At the same time, through the data comparison between Example 9 and Example 1, it shows that when the inlet temperature slightly exceeds the boiling point of PST, that is, controlled at 260 °C, not only can relatively high test accuracy be obtained, but also the energy consumption is relatively small. [[ID=二十二]] [[ID=二十三]]

[0179] [[ID=二十四]]Comparative Example 1 [[ID=二十五]] [[ID=二十六]]

[0180] [[ID=二十七]](1) The method for preparing the standard solution is the same as in Example 1; [[ID=二十八]] [[ID=二十九]]

[0181] (2) Prepare the electrolyte to be tested. Weigh 0.1 g of the electrolyte of the lithium-ion battery to be tested, in which the known content of PST is 1.75%. Add chromatographically pure dichloromethane reagent for dilution so that the content of PST in it is 17.5 mg / L. Shake well and wait for testing;

[0182] (3) Adjust the test parameters of the gas chromatography-mass spectrometry (GC-MS) instrument. The carrier gas is helium, the column flow rate is 1.7 mL / min, the split ratio is 10:1, the inlet temperature is 260 °C, the injection volume is 0.5 μL, the purge is 3 mL / min, and the column temperature program is as follows: keep the temperature constant at 110 °C for 3 min, then increase the temperature at a rate of 10 °C / min to 220 °C and keep the temperature constant for 2 min. The mass spectrometry conditions are as follows: the ion source uses an electron ionization source, the electron energy is 70 eV, the ion source temperature is 230 °C, the interface temperature is 260 °C, the solvent delay time is 1.4 min, and the selected ion monitoring mode is used. The selected ions for the quantitative and qualitative analysis of PST are the same as those in Table 1;

[0183] (4) Test the standard solutions, record the instrument response values corresponding to each standard solution, that is, the peak area (S). Use the software GCMSsolution supporting this equipment to analyze the data and draw the standard curve of PST vs. peak area in the standard solutions, and obtain Figure 11 , the linear equation of the standard curve of PST is S = 724.354×C – 298.716, R 2 = 0.9654, where S is the area of the detection peak of PST, C is the concentration with the unit of mg / L, and R is the coefficient of determination. The closer the value of R 2 is to 1, the better the linear correlation of this equation. <​​​​​​​​​​​​​As can be seen from Comparative Example 1, when the column flow rate is 1.7 mL / min, which does not meet the 1.80-2.00 mL / min limit specified in this invention, the relative deviation of the test results is 1.37%, and the test error is as high as 18.91%. In Example 2, the relative standard deviation is 0.28%, and the test error is 3.07%. It can be seen that compared with Example 2 (column flow rate 1.86 mL / min), when the column flow rate is reduced by 0.16 mL / min (below 1.80 mL / min), the relative standard deviation increases by 1.09%, and the test error increases by 15.84%. All other test process conditions are the same for both examples; only the column flow rate changes. This indicates that even a small change in the column flow rate can lead to a large deviation in the measurement results.

[0189] The PST concentration in the electrolyte of Comparative Example 1 was the same as that in Example 4, but the test conditions were significantly different. The column flow rate in Comparative Example 1 was reduced by 0.16 mL / min compared to Example 4, and the split ratio was higher than that of Example 4 (2:1). However, the limits of detection and quantitation (LODs) differed significantly between the two examples. The values ​​in Example 4 were 0.69 mg / L and 2.08 mg / L, respectively, while those in Comparative Example 1 were 5.36 mg / L and 13.95 mg / L, respectively. It can be seen that the LODs of Comparative Example 1 were significantly higher than those in Example 4. From the measurement results, the relative standard deviation of Comparative Example 1 increased by 0.56%, and the test error increased by 11.31%. This indicates that the test error of Comparative Example 1 also increased significantly. This also shows that the embodiments of the present invention achieve better test accuracy by adjusting the column flow rate and split ratio.

[0190] Comparative Example 2

[0191] (1) The method for preparing the standard solution is the same as in Example 1;

[0192] (2) Prepare the electrolyte to be tested. Weigh 0.1g of the lithium-ion battery electrolyte to be tested, in which the PST content is known to be 2.25%. Add chromatographic grade dichloromethane reagent to dilute it so that the PST content is 22.5mg / L. Shake well and test.

[0193] (3) Adjust the test parameters of the gas chromatography-mass spectrometry (GC-MS) instrument, where the carrier gas is helium, the column flow rate is 2.05 mL / min, the split ratio is 10:1, the injection port temperature is 260℃, the injection volume is 0.5 μL, the purge rate is 3 mL / min, and the column temperature program is: hold at 110℃ for 3 min, increase the temperature to 220℃ at a rate of 10℃ / min, and hold at 2 min. The mass spectrometry conditions are: use an electron ionization source with an electron energy of 70 eV, an ion source temperature of 230℃, an interface temperature of 260℃, a solvent delay time of 1.4 min, select ion monitoring mode, and select the same ions for PST quantitative and qualitative analysis as in Table 1.

[0194] (4) Test the standard solutions, record the instrument response values corresponding to each standard solution, i.e., the peak area (S), analyze the data using the supporting software GCMSsolution of this equipment, plot the standard curve of PST and the peak area in the standard solutions, and obtain Figure 12 , the linear equation of the standard curve of PST is S = 4798.325×C – 663.287, R 2 = 0.9589, where S is the area of the PST detection peak, C is the concentration, with the unit of mg / L, and R is the coefficient of determination. The closer the value of R 2 is to 1, the better the linear correlation of this equation;

[0195] (5) Determine the detection limit and quantification limit. According to the detection requirements of chromatography - mass spectrometry, the detection limit is the sample concentration when the generated signal (peak height) is 3 times the standard deviation of the baseline noise, that is, the concentration corresponding to a signal - to - noise ratio of 3:1. The quantification limit is the sample concentration when the generated signal (peak height) is 10 times the standard deviation of the baseline noise, that is, the concentration corresponding to a signal - to - noise ratio of 10:1. Therefore, at a signal - to - noise ratio of 3:1, the detection limit of PST under this test condition is read as 6.52 mg / L, and at a signal - to - noise ratio of 10:1, the quantification limit of PST under this condition is read as 17.64 mg / L;

[0196] (6) Conduct a quantitative test on the electrolyte to be tested, record the peak area, perform parallel injection analysis 6 times, and calculate the concentration of PST in the electrolyte sample according to the equation obtained in step (4). The specific experimental results are shown in Table 12.

[0197] Table 12 Test results of PST in electrolyte samples

[0198]

[0199] It can be seen from Comparative Example 2 that when the column flow rate is 2.05 mL / min, which does not meet the range of 1.80 - 2.00 mL / min defined in the present invention, the test error is as high as 28.27%. The relative standard deviation in Example 2 is 0.28%, and the test error is 3.07%. It can be seen that compared with Example (column flow rate 1.86 mL / min), when the column flow rate increases by 0.19 mL / min (higher than mL / min), the relative standard deviation increases by 1.39%, and the test error increases by 25.2%. The other test process conditions of the two are the same, only the column flow rate increases. This shows that a small change in the column flow rate will lead to a huge deviation in the measurement result, resulting in a serious decline in the measurement accuracy.

[0200] The PST concentration in the electrolyte of Comparative Example 2 was the same as that in Example 5, but the test conditions were significantly different. The column flow rate in Comparative Example 2 was increased by 0.05 mL / min compared to Example 5, and the split ratio was lower than the 20:1 in Example 5. However, the limits of detection and quantitation (LODs) differed significantly between the two. The values ​​in Example 5 were 0.77 mg / L and 2.20 mg / L, respectively, while those in Comparative Example 2 were 6.52 mg / L and 17.64 mg / L, respectively. It can be seen that the LODs of Comparative Example 2 were significantly higher than those in Example 5. From the measurement results, the relative standard deviation of Comparative Example 2 increased by 1.22%, and the test error increased by 25.29%. This also indicates that the embodiments of the present invention, through the adjustment of the column flow rate and split ratio, have excellent test accuracy.

[0201] Therefore, the high-precision method for detecting the content of 1,3-propenesulfonate lactone in electrolyte proposed in this invention is suitable for detecting the PST content in electrolyte systems, especially for detecting trace amounts of PST in electrolytes. This method has low detection and quantitation limits, can be used to measure the PST content in electrolytes, and can accurately measure the PST content in electrolytes. It has good repeatability, is easy to operate, and effectively improves the detection accuracy of PST. Therefore, it is helpful for the research, design, and optimization of electrolyte components, and can also be used to analyze and explore battery failure mechanisms.

[0202] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-precision method for detecting the content of 1,3-propenesulfonate lactone in an electrolyte, characterized in that, The detection method includes: 1,3-propenesulfonyl lactone (PST) was dissolved in an organic solvent to prepare a set of PST standard solutions with a concentration gradient; the set of PST standard solutions with a concentration gradient included multiple PST standard solutions with different concentrations; wherein, the organic solvent included chromatographically pure dichloromethane; A chromatographic column is selected, wherein the stationary phase of the column is 5% phenyl-95% dimethyl polysiloxane, the column length is 25-60m, the inner diameter is 0.25-0.50mm, and the inner coating thickness is 0.25-0.50μm; Adjust the gas chromatography-mass spectrometry (GC-MS) test parameters; the chromatographic test parameters are as follows: carrier gas is helium, column flow rate is 1.80-2.00 mL / min, split ratio is 20:1-2:1, injection port temperature is 260℃-280℃, injection volume is 0.5uL-1uL, purge rate is 3mL / min-5mL / min; column temperature program: hold at 100℃-110℃ for 3min-5min, increase temperature at a rate of 5℃-10℃ / min to 200℃-220℃, hold at 2min-3min; the mass spectrometry test parameters are as follows: use an electron ionization source, ion source temperature is 200℃-230℃, interface temperature is 250℃-280℃, solvent delay time is 1.0min-2.0min; Each PST standard solution in the PST standard solution group with concentration gradient was detected by a gas chromatography-mass spectrometry system with adjusted parameters. The detection peak area of ​​each PST standard solution was recorded, and a standard curve was determined based on the PST concentration in each PST standard solution and the corresponding detection peak area. Select the electrolyte to be tested, pretreat the electrolyte, and use a gas chromatography-mass spectrometry system with adjusted parameters to detect the pretreated electrolyte, obtain the measured peak area, and find the corresponding value in the standard curve based on the measured peak area to obtain the concentration of PST in the electrolyte.

2. The detection method according to claim 1, characterized in that, The PST standard solution set includes at least 6 different concentrations of PST standard solutions; the concentration of each PST standard solution in the PST standard solution set is between 0 and 30 mg / L.

3. The detection method according to claim 2, characterized in that, The concentrations of the PST standard solutions in the PST standard solution group were 0 mg / L, 5 mg / L, 10 mg / L, 15 mg / L, 20 mg / L, 25 mg / L and 30 mg / L, respectively.

4. The detection method according to claim 1, characterized in that, The determination of the standard curve based on the PST concentration and detection peak area in the standard solution specifically involves: determining the standard curve using a standard curve equation; wherein the standard curve equation is: S = kC - b, where S is the detection peak area of ​​PST, C is the PST concentration, k is the slope obtained by linear simulation based on the test results of the standard solution under the current test conditions, b is the peak area corresponding to a PST concentration of 0 obtained from the test results of the standard solution under the current test conditions, and the coefficient of determination R of the standard curve equation under the current test conditions is... 2 ≥0.

996.

5. The detection method according to claim 1, characterized in that, The method further includes: detecting each PST standard solution in the PST standard solution group with concentration gradient using a gas chromatography-mass spectrometry system with adjusted parameters, recording the detection peak area corresponding to each PST standard solution, and determining the limit of detection and limit of quantitation under the current test conditions based on the PST concentration in each PST standard solution and the corresponding detection peak area; the limit of detection is 0.64 mg / L-4 mg / L, and the limit of quantitation is 1.93 mg / L-12 mg / L; The detection limit is the sample concentration corresponding to a peak height of 3 times the baseline noise standard, i.e., a signal-to-noise ratio of 3:1; the quantitation limit is the sample concentration corresponding to a peak height of 10 times the baseline noise standard, i.e., a signal-to-noise ratio of 10:

1.

6. The detection method according to claim 1, characterized in that, The pretreatment specifically includes: diluting the electrolyte to be tested with dichloromethane; the content of PST in the diluted electrolyte is greater than or equal to 2.54 mg / L.

7. The detection method according to any one of claims 1-6, characterized in that, The method involves using a gas chromatography-mass spectrometry (GC-MS) instrument with adjusted parameters to detect the pretreated electrolyte, obtaining the measured peak area, and then using the measured peak area to find the corresponding value in the standard curve to determine the concentration of PST in the electrolyte. Specifically, this includes: The pretreated electrolyte was tested multiple times using a gas chromatography-mass spectrometry (GC-MS) instrument with adjusted parameters. Multiple detection peak areas were obtained through these multiple tests. The corresponding PST concentrations in the electrolytes were then determined by searching the standard curve based on the measured peak areas. The average PST concentration in the electrolytes was then calculated as the final PST concentration.

8. The detection method according to any one of claims 1-6, characterized in that, The electrolyte to be tested includes: original electrolyte that has not been circulated or aged electrolyte that has undergone any number of cycles.

9. The detection method according to any one of claims 1-6, characterized in that, The split ratio is 20:1-10:1; The injection port temperature is 260℃-265℃.

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