Method for rapidly detecting 2-ethylhexanol based on ion mobility spectrometry and application thereof

Abstract

The invention discloses a method for rapidly detecting 2-ethylhexanol based on ion mobility spectrometry and application of the method, and belongs to the technical field of application, analysis and detection of ion mobility spectrometry. The detection method established by the invention is suitable for detecting 2-ethylhexanol in any environment, the application range of samples is expanded, a complicated sample pretreatment process is not needed, and online rapid detection and early warning are facilitated. Compared with other lithium battery thermal runaway early warning related detection equipment, the established detection method has the core advantages of shortest response time and highest sensitivity, has the outstanding characteristics of convenient operation and real-time monitoring, and can more efficiently adapt to the on-site rapid early warning requirement; in a lithium battery short-circuit experiment, when the surface temperature of the battery is increased by about 76 DEG C, the ion mobility spectrometry rapidly detects a 2-ethylhexanol spectrum peak, and thermal runaway does not occur at 100 DEG C. The method is effectively applied to early warning detection of thermal runaway of the lithium battery.

Description

Technical Field

[0001] This invention belongs to the field of ion mobility spectrometry application and analysis detection technology, specifically relating to a method for rapid detection of 2-ethylhexanol based on ion mobility spectrometry and its application. Background Technology

[0002] 2-Ethylhexanol, as a plasticizer precursor, reacts with organic acids to form ester plasticizers, which improve the flexibility and processability of plastics. 2-Ethylhexanol is commonly used in the synthesis of polyvinyl chloride (PVC) plasticizers such as diethylhexyl phthalate (DOP), diethylhexyl phthalate (DOTP), and trioctyl trimellitate (TOTM), and constitutes a large proportion of these products. Long-term inhalation can cause headaches, dizziness, and fatigue (due to vapor irritation of the central nervous system); high concentrations (>500 ppm) can irritate the respiratory mucosa, causing coughing, chest tightness, and sore throat, and in severe cases, bronchitis. Besides posing a danger to the respiratory tract, 2-ethylhexanol vapor is also a key indicator of cable overheating, crucial for early warning of potential electrical fires. However, due to the chemical stability of 2-ethylhexanol, traditional chemical resistance gas sensors are unsuitable for real-time detection.

[0003] Currently, methods for detecting 2-ethylhexanol gas mainly include chromatographic analysis (gas chromatography GC, gas chromatography-mass spectrometry GC-MS), spectroscopic analysis (photoionization detection PID, FTIR / NDIR infrared spectroscopy), and sensor technology (semiconductor sensors, electrochemical sensors). Each method has its own emphasis in terms of detection performance, applicable scenarios, and practical applications: GC and GC-MS are suitable for high-precision laboratory analysis, but the equipment is large, the operation is complex, and the response time is on the order of minutes, resulting in high costs; PID and infrared spectroscopy are highly susceptible to interference from other VOCs, and infrared spectroscopy is easily affected by moisture; semiconductor and electrochemical sensors have low sensitivity and short lifespans.

[0004] Ion mobility spectrometry (IMS) possesses core characteristics such as fast response speed (seconds), small size and portability, low detection limit (ppb), and strong anti-interference ability, making it particularly suitable for the real-time field detection of 2-ethylhexanol. Its second-level response speed can quickly capture the release signal of 2-ethylhexanol in scenarios such as lithium battery thermal runaway, enabling real-time on-site monitoring without complex sample pretreatment. The ppb-level detection limit can accurately capture early trace amounts of the target gas, providing sufficient time for hazard warning. Its portable design facilitates mobile use in industrial sites and battery storage scenarios. This technology meets the requirements for real-time, on-site, and high-sensitivity detection of 2-ethylhexanol, making it an efficient and reliable detection solution for scenarios such as early warning of lithium battery thermal runaway.

[0005] Therefore, how to provide a method for rapid detection of 2-ethylhexanol based on ion mobility spectrometry for early warning of thermal runaway risk in lithium batteries has become an important issue that urgently needs to be addressed. Summary of the Invention

[0006] Therefore, the purpose of this invention is to provide a method for rapid detection of 2-ethylhexanol based on ion mobility spectrometry and its application.

[0007] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for rapid detection of 2-ethylhexanol based on ion mobility spectrometry, comprising the following steps: S1, introduce 2-ethylhexanol standard sample and 2-ethylhexanol samples of a series of concentrations into the ion migration tube along with acetone gas carried by clean air; S2, under vacuum ultraviolet light irradiation in the reaction zone, acetone gas undergoes an ionization reaction to produce reactant ions (C3H6O)2·H2O. +， The 2-ethylhexanol standard sample and a series of 2-ethylhexanol samples at various concentrations react with the reagent ions in the reaction zone to generate the characteristic product ion C8H from the 2-ethylhexanol standard sample and the series of 2-ethylhexanol samples at various concentrations. 18 O·C3H6O·H + ; S3, the characteristic product ions of the 2-ethylhexanol standard sample and the series of 2-ethylhexanol samples enter the migration region through the ion gate, travel opposite to the gas in the drift gas path, and finally reach the Faraday disk to generate an electrical signal and display the standard spectrum and series spectrum. S4. Obtain the migration time and peak position from the standard spectrum, and calculate the reduced mobility K value. S5. Qualitative analysis was performed based on the reduced mobility K value. The signal intensity of a series of spectra was calculated, and the relationship curve between the concentration and signal intensity of a series of 2-ethylhexanol samples was established. S6. Based on the relationship curve and the signal intensity of the sample to be tested, the concentration of 2-ethylhexanol in the sample to be tested is obtained.

[0008] Among them, the 2-ethylhexanol samples of various concentrations in S1 were introduced in the form of vapor.

[0009] Neutral molecules that have not undergone reaction are extracted from the tail gas outlet of the reaction zone.

[0010] Based on the above technical solution, the ionization reaction principle in S2 is further as follows: .

[0011] Based on the above technical solution, the chemical reaction principle in S2 is further as follows: .

[0012] Based on the above technical solution, the formula for calculating the reduced mobility K value in S4 is as follows: ; In the formula: The unit is cm. 2 V -1 s -1 The reduced mobility of the analyte ions The unit is cm. 2 V -1 s -1 The reduced mobility of the standard ions, The migration time of analyte ions is expressed in milliseconds (ms). The migration time of standard ions is expressed in milliseconds (ms).

[0013] In the positive ion mode, the migration time of 2-ethylhexanol was 4.28 ms, and the reduced mobility of 2-ethylhexanol was... It is 1.38 cm 2 V -1 s -1 .

[0014] Based on the above technical solution, the ion mobility spectrometry adopts a positive ion mode with negative pressure injection, including: a vacuum ultraviolet lamp, an ion gate, and a Faraday disk. The ion gate divides the ion mobility tube into a reaction zone and a migration zone. The reaction zone is provided with an inlet, an exhaust gas port connected to a pump, and a dopant gas inlet. The gas path sequence is as follows: the exhaust gas port is close to the vacuum ultraviolet lamp, and the dopant inlet is coaxial with the inlet. The migration zone is provided with a drift gas inlet, and the drift gas path is perpendicular to the ion gate.

[0015] Based on the above technical solution, further, the ion mobility spectrometry uses a novel radio frequency VUV lamp as the ionization source, and the migration region voltage is set to 600V / cm; the dopant gas flow rate is 100mL / min, the drift gas flow rate is 400mL / min, and the exhaust gas flow rate at the tail gas port is 700mL / min. The exhaust gas flow rate is greater than the sum of the dopant gas flow rate, the drift gas flow rate, and the inlet flow rate; the dopant gas path, the drift gas path, and the tail gas path are all connected to mass flow meters to control the gas flow rate; the tail gas port is connected to a vacuum pump.

[0016] Secondly, this invention provides the application of the above-mentioned method for rapid detection of 2-ethylhexanol based on ion mobility spectrometry in early warning of thermal runaway risk in lithium batteries.

[0017] Based on the above technical solution, further, S101, detect the concentration of 2-ethylhexanol in the external PVC of the lithium battery at 60-120℃, and establish the correspondence between the concentration of 2-ethylhexanol and the temperature of the external PVC of the lithium battery. S102, detect the concentration of 2-ethylhexanol in the PVC outside the lithium battery, and obtain the temperature of the PVC outside the lithium battery based on the corresponding relationship.

[0018] Based on the above technical solution, further, when the external PVC temperature of the lithium battery in S102 reaches 80°C, an alarm is triggered.

[0019] The normal operating temperature range of lithium batteries is 0-45℃. When the temperature rises to 80℃, the solid electrolyte interface inside the battery gradually melts, threatening battery safety and triggering thermal runaway. When heated, the plastic film on the surface of a lithium battery releases a large amount of 2-ethylhexanol vapor. To address this characteristic, the detection method of this invention can respond to the 2-ethylhexanol signal within 4 seconds, with a detection limit as low as 0.44 ppb, providing a rapid and effective solution for early warning of thermal runaway in lithium batteries.

[0020] Among them, the PVC outside the lithium battery releases different concentrations of 2-ethylhexanol at temperatures of around 60-120℃. As the temperature increases, the amount of 2-ethylhexanol released gradually increases. Based on the relationship between the change in the concentration gradient of 2-ethylhexanol released by the PVC and the temperature, the safety state of the lithium battery can be inferred, thereby achieving early warning of the risk of thermal runaway of the lithium battery.

[0021] PVC refers to plastic film.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1. The detection method established in this invention is applicable to the detection of 2-ethylhexanol in any environment, expanding the scope of sample applicability, eliminating the need for complex sample pretreatment processes, and facilitating rapid online detection and early warning.

[0023] 2. Compared with other detection equipment related to early warning of thermal runaway in lithium batteries, the detection method established in this invention has the core advantages of the shortest response time and the highest sensitivity, while also featuring convenient operation and real-time monitoring. It can more efficiently adapt to the needs of rapid on-site early warning. In the lithium battery short-circuit experiment, when the battery surface temperature rises to about 76°C, the ion mobility spectrometry quickly detects the 2-ethylhexanol peak, and no thermal runaway occurs even at 100°C. The method is effectively applied to the early warning detection of thermal runaway in lithium batteries. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is the ion mobility spectrometry spectrum for detecting 2-ethylhexanol in Example 2 of the present invention; Figure 2 This is the ion mobility spectrometry detection curve for 2-ethylhexanol in Example 2 of the present invention; Figure 3 The stability curve of 2-ethylhexanol was obtained by ion mobility spectrometry detection in Example 3 of this invention. Figure 4 This is a simulated lithium battery short-circuit experiment in Example 4 of the present invention. As the short-circuit time increases, the battery surface temperature gradually increases, as shown in the 2-ethylhexanol signal intensity curve. Detailed Implementation

[0026] The present invention will be described in detail below with reference to the embodiments. However, the implementation of the present invention is not limited thereto. Obviously, the embodiments described below are only some embodiments of the present invention. For those skilled in the art, other similar embodiments can be obtained without creative effort and all fall within the protection scope of the present invention.

[0027] Example 1 This embodiment tests a standard sample of 2-ethylhexanol.

[0028] 1) The standard sample 2-ethylhexanol to be tested is introduced into the ion migration tube; 2) The dopant gas carried by clean air enters the ion migration tube through the dopant gas and is ionized under the irradiation of the vacuum ultraviolet lamp in the reaction zone to produce reaction reagent ions; the dopant is acetone, and the dopant gas is clean air and acetone vapor. 3) The sample molecules to be tested that enter the ion migration tube in step 1) react chemically with the reagent ions in step 2) in the reaction zone to generate characteristic product ions of the sample to be tested. 4) The generated characteristic product ions enter the migration region through the ion gate, travel opposite to the gas in the drift gas path, and finally reach the Faraday disk and display the spectrum. The migration time is 4.28 ms. Meanwhile, the neutral molecules that have not reacted are extracted from the tail gas port of the reaction region by the gas pump, thereby realizing the separation and detection of the sample.

[0029] Example 2 This embodiment involves the detection of a series of 2-ethylhexanol samples at different concentrations.

[0030] 2-Ethylhexanol concentrations ranging from 10 to 50 ppb were prepared using a stepwise dilution method. During the experiment, the migration tube temperature was maintained at 120℃, the dopant bottle temperature at 40℃, the carrier gas flow rate at 100 mL / min, the drift gas flow rate at 400 mL / min, the dopant flow rate at 100 mL / min, and the pump gas flow rate at 700 mL / min. Each concentration of sample was tested in triplicate. The injected 2-ethylhexanol samples yielded... Figure 1 The ion migration spectrum shown indicates that the migration times of 4.28 ms and 5.26 ms are characteristic peaks of 2-ethylhexanol, with the 4.28 ms peak being the major product ion peak at lower concentrations. Therefore, by tracking the signal intensity of this peak (4.28 ms) and establishing the relationship curve between different 2-ethylhexanol sample concentrations and signal intensities, the following can be obtained: Figure 2 The quantitative curve is available, and the detection limit can be as low as 0.44 ppb.

[0031] Example 3 Using the apparatus described in Example 1, 2-ethylhexanol was diluted to concentrations of 35 ppb and 95 ppb. The product ion peak (4.28 ms) was tracked, switching between 35 ppb and 95 ppb, with the detection time at each concentration being 3 minutes before switching to the next concentration condition. Figure 3 The results show that 2-ethylhexanol has good stability; repeated experiments over two days showed stability (RSD) of 1.59% and 2.26%.

[0032] Example 4 Using the apparatus described in Example 1, a short circuit in a lithium battery was simulated, and detection was performed simultaneously in an atmospheric environment. The positive and negative electrodes of the lithium battery were connected to form a short circuit. As the short circuit time increased, the battery surface temperature rose and 2-ethylhexanol was released. This was detected by ion mobility spectrometry. Figure 4 A distinct product ion peak appears when the temperature rises to around 76°C, at which point the concentration of 2-ethylhexanol is approximately 33 ppb.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for rapid detection of 2-ethylhexanol based on ion mobility spectrometry, characterized in that, Includes the following steps: S1, introduce 2-ethylhexanol standard sample and 2-ethylhexanol samples of a series of concentrations into the ion migration tube along with acetone gas carried by clean air; S2, under vacuum ultraviolet light irradiation in the reaction zone, acetone gas undergoes an ionization reaction to produce reactant ions (C3H6O)2·H2O. +， The 2-ethylhexanol standard sample and a series of 2-ethylhexanol samples at various concentrations react with the reagent ions in the reaction zone to generate the characteristic product ion C8H from the 2-ethylhexanol standard sample and the series of 2-ethylhexanol samples at various concentrations. 18 O·C3H6O·H + ; S3, the characteristic product ions of the 2-ethylhexanol standard sample and the series of 2-ethylhexanol samples enter the migration region through the ion gate, travel opposite to the gas in the drift gas path, and finally reach the Faraday disk to generate an electrical signal and display the standard spectrum and series spectrum. S4. Obtain the migration time and peak position from the standard spectrum, and calculate the reduced mobility K value. S5. Qualitative analysis was performed based on the reduced mobility K value. The signal intensity of a series of spectra was calculated, and the relationship curve between the concentration and signal intensity of a series of 2-ethylhexanol samples was established. S6. Based on the relationship curve and the signal intensity of the sample to be tested, the concentration of 2-ethylhexanol in the sample to be tested is obtained.

2. The method for rapid detection of 2-ethylhexanol based on ion mobility spectrometry according to claim 1, characterized in that, The ionization reaction principle in S2 is as follows: 。 3. The method for rapid detection of 2-ethylhexanol based on ion mobility spectrometry according to claim 1, characterized in that, The chemical reaction principle in S2 is as follows: 。 4. The method for rapid detection of 2-ethylhexanol based on ion mobility spectrometry according to claim 1, characterized in that, The formula for calculating the reduced mobility K value in S4 is as follows: ； In the formula: The unit is cm. 2 V -1 s -1 The reduced mobility of the analyte ions The unit is cm. 2 V -1 s -1 The reduced mobility of the standard ions, The migration time of analyte ions is expressed in milliseconds (ms). The migration time of standard ions is expressed in milliseconds (ms).

5. The method for rapid detection of 2-ethylhexanol based on ion mobility spectrometry according to claim 1, characterized in that, The ion mobility spectrometry uses a positive ion mode with negative pressure injection, including a vacuum ultraviolet lamp, an ion gate, and a Faraday disk. The ion gate divides the ion mobility tube into a reaction zone and a migration zone. The reaction zone has an inlet, an exhaust gas port connected to a pump, and a dopant gas inlet. The gas path sequence is as follows: the exhaust gas port is close to the vacuum ultraviolet lamp, and the dopant inlet is coaxial with the inlet. The migration zone has a drift gas inlet, and the drift gas path is perpendicular to the ion gate.

6. The method for rapid detection of 2-ethylhexanol based on ion mobility spectrometry according to claim 1, characterized in that, The ion mobility spectrometry uses a novel radio frequency VUV lamp as the ionization source, with the migration region voltage set to 600 V / cm. The dopant gas flow rate is 100 mL / min, the drift gas flow rate is 400 mL / min, and the exhaust gas flow rate at the tail gas port is 700 mL / min. The exhaust gas flow rate is greater than the sum of the dopant gas flow rate, the drift gas flow rate, and the inlet flow rate. Mass flow meters are connected to the dopant gas path, the drift gas path, and the tail gas path to control the gas flow rate. An exhaust pump is connected to the tail gas port.

7. The application of the method for rapid detection of 2-ethylhexanol based on ion mobility spectrometry as described in any one of claims 1 to 6 in early warning of thermal runaway risk in lithium batteries.

8. The application according to claim 7, characterized in that, S101, detect the concentration of 2-ethylhexanol in the external PVC of the lithium battery at 60-120℃, and establish the correspondence between the concentration of 2-ethylhexanol and the temperature of the external PVC of the lithium battery. S102, detect the concentration of 2-ethylhexanol in the PVC outside the lithium battery, and obtain the temperature of the PVC outside the lithium battery based on the corresponding relationship.

9. The application according to claim 8, characterized in that, An alarm is triggered when the external PVC temperature of the lithium battery in S102 reaches 80°C.

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