A method for intermittently collecting and analyzing substances released from lithium battery electrolyte in the air

Abstract

This invention relates to the field of battery testing technology, and more particularly to a method for intermittently collecting and analyzing substances released from lithium battery electrolyte in the air. Employing ion mobility spectrometry (IMP) in positive ion mode, with ethanol as a dopant, an intermittent pipeline sampling device is used to extract substances released from the air by the lithium battery electrolyte from the environment. The extracted samples are then analyzed to obtain spectra of peak height versus migration time and characteristic peak height versus continuous analysis time. This detection method exhibits high specificity and fast detection speed, making it suitable for the analysis and monitoring of substances released from lithium battery electrolyte in the air.

Description

Technical Field

[0001] This invention relates to the field of battery testing technology, and in particular to a method for intermittently collecting and analyzing substances released from lithium battery electrolyte in the air. Background Technology

[0002] Lithium-ion batteries are among the most widely used batteries in electronic products and a crucial power source for the new energy vehicle industry. Analyzing and detecting substances released from lithium-ion battery electrolytes into the air can reveal changes in lithium-ion batteries during leakage, providing analytical methods to improve battery safety. Lithium-ion battery electrolytes consist of high-purity organic solvents, lithium electrolyte salts (lithium hexafluorophosphate, LiFL6), and necessary additives. The main components of the organic solvents are diethyl carbonate, dimethyl carbonate, ethylene carbonate, and propylene carbonate.

[0003] In existing technologies, gas chromatography (GC) is the primary method for detecting lithium-ion battery electrolytes and substances released into the air. For most lithium-ion battery electrolyte formulations, direct injection GC is a mature method with good reproducibility, meeting analytical requirements and thus widely used. However, GC uses intermittent injection via a micro-syringe and cannot automate sampling. This is particularly problematic when the sample source is inaccessible to personnel or when repeated rapid sampling is not possible, necessitating continuous sampling. However, continuous sampling can lead to continuous dilution of the sample when analyzing intermittently released substances, potentially resulting in samples falling below the detection limit and becoming undetectable.

[0004] Ion mobility spectrometry (IMS) is a technique for separating and identifying ions based on the difference in their migration time. It detects and identifies different types of substances based on the difference in the migration rate of gas-phase ions in a weak electric field, and is suitable for trace detection of volatile organic compounds. Summary of the Invention

[0005] The purpose of this invention is to provide a method for intermittently collecting and analyzing substances released from lithium battery electrolyte in the air.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A method for intermittently collecting and analyzing substances released from lithium battery electrolyte in the air, using an intermittent pipeline air extraction sampling device to extract substances released from lithium battery electrolyte in the air from the environment. The intermittent pipeline air extraction sampling device includes an inlet pipe, an outlet pipe, and a pipeline exhaust fan. One end of the inlet pipe is an air inlet, one end of the outlet pipe is connected to the pipeline exhaust fan, and the other end is connected to the inlet pipe. An insertion port is provided on the inlet pipe.

[0008] The method includes the following steps:

[0009] (1) Using ion mobility spectrometry, in positive ion mode, ethanol is used as a dopant. The pipeline exhaust fan is turned on intermittently, and the lithium battery electrolyte is extracted from the environment through the air inlet pipe and released into the air outlet pipe.

[0010] (2) The sample is injected through the inlet of the ion mobility spectrometer to obtain the spectrum of peak height versus migration time and the spectrum of characteristic peak height versus continuous analysis time.

[0011] In the above technical solution, the ratio of the characteristic peak migration time of the lithium battery electrolyte to the ethanol migration time is 1.03-1.45.

[0012] In the above technical solution, the inner diameter of the inlet of the ion mobility spectrometer is 20-50 mm, the pumping flow rate is 100-900 liters / minute, and the pumping speed of the inlet is 3-23 m / s.

[0013] Furthermore, in the above technical solution, the intermittent pipeline air extraction sampling device also includes a windproof cap, which is connected to the exhaust port of the pipeline exhaust fan.

[0014] In the above technical solution, the ratio of the intermittent opening time to the closing time of the duct exhaust fan is further 1 to 6:1.

[0015] In the above technical solution, the intermittent opening time of the duct exhaust fan is 5-30 seconds, and the closing time is 5 seconds.

[0016] In the above technical solution, the intermittent pipeline air extraction sampling device has 1-6 air inlet pipes.

[0017] Furthermore, in the above technical solution, the intermittent pipeline air extraction sampling device also includes a power supply battery, which is connected to the pipeline exhaust fan, and the power supply battery is a solar panel or an energy storage battery.

[0018] The beneficial effects of this invention are as follows:

[0019] The detection method has good specificity and fast detection speed, and is suitable for the analysis and monitoring of substances released from lithium battery electrolytes in the air.

[0020] Intermittent sampling involves sampling for a period of time and then stopping for a period of time. Under controlled intervals, the concentration of the sample will fluctuate between high and low levels. High concentrations will exceed the detection limit, thus detecting these concentration variations. Therefore, intermittent sampling and detection offer unique advantages over continuous sampling analysis. Furthermore, compared to conventional intermittent sampling methods with proportional time and low sampling flow rates, this invention achieves efficient detection of characteristic peaks of the analyte under high-flow-rate sampling conditions by setting the time interval and ratio between on and off sampling, thereby increasing the proportion of on-time sampling. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the intermittent pipeline air extraction and sampling device of the present invention;

[0022] The components include: 1. Inlet pipe, 2. Insertion port, 3. Outlet pipe, 4. Duct-type exhaust fan, 5. Windproof cap, and 6. Power supply battery.

[0023] Figure 2 This is a schematic diagram illustrating the intermittent collection and analysis of substances released from lithium battery electrolyte in the air according to the present invention.

[0024] Figure 3 The ion migration spectrum of the 0.1 ppm lithium battery electrolyte gas in Example 1 is shown as a characteristic peak.

[0025] Figure 4 This is a graph showing the variation of the peak height of the characteristic peaks of substances released from the lithium battery electrolyte in the air during intermittent sampling in Example 1. Detailed Implementation

[0026] The following examples are intended to enable those skilled in the art to more fully understand the present invention, but do not limit the invention in any way.

[0027] like Figure 1 As shown, the intermittent pipeline air extraction sampling device includes an inlet pipe 1, an outlet pipe 3, a pipeline exhaust fan 4, a windproof cap 5, and a power supply battery 6. One end of the inlet pipe 1 is an air inlet, one end of the outlet pipe 3 is connected to the pipeline exhaust fan 4, and the other end is connected to the inlet pipe 1. An insertion port 2 is provided on the inlet pipe 1. The windproof cap 5 is connected to the exhaust port of the pipeline exhaust fan 4. The power supply battery 6 is connected to the pipeline exhaust fan 4. The power supply battery 6 is a solar panel or an energy storage battery. The power supply battery 6 is controlled by an intermittent timer.

[0028] A method for intermittently collecting and analyzing substances released from lithium battery electrolyte in the air employs ion mobility spectrometry (IMS) in positive ion mode with ethanol as a dopant. First, an intermittent pipeline sampling device is used, with the pipeline exhaust fan intermittently activated to extract substances released from the air by the lithium battery electrolyte through the inlet pipe into the outlet pipe. Second, the gas is extracted and analyzed through the inlet of the intermittent pipeline sampling device via the inlet of the ion mobility spectrometer, yielding spectra of peak height versus migration time and characteristic peak height versus continuous analysis time.

[0029] Analysis conditions: migration tube temperature 140℃, injection tube temperature 190℃, ethanol dopant incubation temperature 50℃; total voltage 8.1 kV, unidirectional gas flow, door opening time 50 μs, drift gas flow rate 1.0 L / min, ethanol-containing carrier gas flow rate 0.1 L / min, pumping flow rate 1.2 L / min, calculated pumping sampling flow rate as 1.2 - 1.0 - 0.1 = 0.1 L / min; pumping sampling for analysis, each analysis cycle is 5 seconds (cumulative 42 spectra);

[0030] Take 1.0 ml of the original lithium battery electrolyte (containing ethyl methyl carbonate EMC: diethyl carbonate DEC: ethylene carbonate EC = 1:1:1) into a 1.5 ml open bottle with a bottle mouth diameter of 5 mm. Place the bottle on the center line of the air inlet of the intermittent pipeline gas sampling device, and collect the released substances through intermittent gas extraction for analysis. Monitor the peak height of the characteristic peak within 3.8 to 5.5 ms.

[0031] in:

[0032] The inner diameter of the air intake is between 20-50 mm;

[0033] The air flow rate is between 100-900 liters per minute;

[0034] The pumping speed at the air inlet is between 3 and 23 meters per second;

[0035] The intermittent start-up time of the ducted exhaust fan is 5-30 seconds, and the shut-off time is 5 seconds.

[0036] The intermittent pipeline air sampling device has 1-6 air inlet pipes, preferably 2.

[0037] Example 1

[0038] A method for intermittently collecting and analyzing substances released from lithium battery electrolyte in the air employs ion mobility spectrometry (IMS) in positive ion mode with ethanol as a dopant. First, an intermittent pipeline sampling device is used, with the pipeline fan intermittently activated to extract substances released from the lithium battery electrolyte in the air through the inlet pipe into the outlet pipe. Second, the gas is extracted and analyzed through the inlet of the ion mobility spectrometer from the insertion port of the intermittent pipeline sampling device, yielding a spectrum of peak height versus migration time and a spectrum of characteristic peak height versus continuous analysis time.

[0039] Analysis conditions: migration tube temperature 140℃, injection tube temperature 190℃, ethanol dopant incubation temperature 50℃; total voltage 8.1 kV, unidirectional gas flow, door opening time 50 μs, drift gas flow rate 1.0 L / min, ethanol-containing carrier gas flow rate 0.1 L / min, pumping flow rate 1.2 L / min, calculated pumping sampling flow rate as 1.2 - 1.0 - 0.1 = 0.1 L / min; pumping sampling for analysis, each analysis cycle is 5 seconds (cumulative 42 spectra);

[0040] Take 1.0 ml of the original lithium battery electrolyte (containing ethyl methyl carbonate EMC: diethyl carbonate DEC: ethylene carbonate EC = 1:1:1) into a 1.5 ml open bottle with a bottle mouth diameter of 5 mm. Place the bottle on the center line of the air inlet of the intermittent pipeline gas sampling device, and collect the released substances through intermittent gas extraction for analysis. Monitor the peak height of the characteristic peak within 3.8 to 5.5 ms.

[0041] in:

[0042] The inner diameter of the air intake is 50 mm;

[0043] The air extraction flow rate is 900 liters per minute;

[0044] The pumping speed at the air inlet is 3.8 m / s;

[0045] The intermittent start-up time of the ducted exhaust fan is 5 seconds, and the shut-off time is 5 seconds.

[0046] The intermittent pipeline air extraction sampling device has two air inlets;

[0047] The analysis results are shown in Table 1. Figure 3 and Figure 4 ,in:

[0048] The characteristic peak migration times of the substances released by the lithium battery electrolyte in air were 3.9, 4.1, 4.4, 5.2, and 5.5 ms, while the characteristic peak migration time of ethanol was 3.8 ms. The ratios of the characteristic peak migration times of the substances released by the lithium battery electrolyte in air to the migration times of ethanol were 1.03, 1.08, 1.16, 1.37, and 1.45, respectively.

[0049] The average cumulative peak heights of the 3.9ms characteristic peaks were 29, 9, 7, and 4 volts, respectively (cumulative 42 spectra, 5 seconds).

[0050] The average cumulative peak heights of the 4.1ms characteristic peaks were 7, 5, 3, and 3 volts, respectively (cumulative 42 spectra, 5 seconds).

[0051] Example 2

[0052] A method for intermittently collecting and analyzing substances released from lithium battery electrolyte in the air employs ion mobility spectrometry (IMS) in positive ion mode with ethanol as a dopant. First, an intermittent pipeline sampling device is used, with the pipeline fan intermittently activated to extract substances released from the lithium battery electrolyte in the air through the inlet pipe into the outlet pipe. Second, the gas is extracted and analyzed through the inlet of the ion mobility spectrometer from the insertion port of the intermittent pipeline sampling device, yielding a spectrum of peak height versus migration time and a spectrum of characteristic peak height versus continuous analysis time.

[0053] Analysis conditions: migration tube temperature 140℃, injection tube temperature 190℃, ethanol dopant incubation temperature 50℃; total voltage 8.1 kV, unidirectional gas flow, door opening time 50 μs, drift gas flow rate 1.0 L / min, ethanol-containing carrier gas flow rate 0.1 L / min, pumping flow rate 1.2 L / min, calculated pumping sampling flow rate as 1.2 - 1.0 - 0.1 = 0.1 L / min; pumping sampling for analysis, each analysis cycle is 5 seconds (cumulative 42 spectra);

[0054] Take 1.0 ml of the original lithium battery electrolyte (containing ethyl methyl carbonate EMC: diethyl carbonate DEC: ethylene carbonate EC = 1:1:1) into a 1.5 ml open bottle with a bottle mouth diameter of 5 mm. Place the bottle on the center line of the air inlet of the intermittent pipeline gas sampling device, and collect the released substances through intermittent gas extraction for analysis. Monitor the peak height of the characteristic peak within 3.8 to 5.5 ms.

[0055] in:

[0056] The inner diameter of the air intake is 20 mm;

[0057] The air extraction flow rate is 900 liters per minute;

[0058] The pumping speed at the air inlet is 23 m / s;

[0059] The intermittent start-up time of the ducted exhaust fan is 5 seconds, and the shut-off time is 5 seconds.

[0060] The average cumulative peak height of the 3.9ms characteristic peak is 8 volts (cumulative 42 spectra, 5 seconds).

[0061] Example 3

[0062] A method for intermittently collecting and analyzing substances released from lithium battery electrolyte in the air employs ion mobility spectrometry (IMS) in positive ion mode with ethanol as a dopant. First, an intermittent pipeline sampling device is used, with the pipeline fan intermittently activated to extract substances released from the lithium battery electrolyte in the air through the inlet pipe into the outlet pipe. Second, the gas is extracted and analyzed through the inlet of the ion mobility spectrometer from the insertion port of the intermittent pipeline sampling device, yielding a spectrum of peak height versus migration time and a spectrum of characteristic peak height versus continuous analysis time.

[0063] Analysis conditions: migration tube temperature 140℃, injection tube temperature 190℃, ethanol dopant incubation temperature 50℃; total voltage 8.1 kV, unidirectional gas flow, door opening time 50 μs, drift gas flow rate 1.0 L / min, ethanol-containing carrier gas flow rate 0.1 L / min, pumping flow rate 1.2 L / min, calculated pumping sampling flow rate as 1.2 - 1.0 - 0.1 = 0.1 L / min; pumping sampling for analysis, each analysis cycle is 5 seconds (cumulative 42 spectra);

[0064] Take 1.0 ml of the original lithium battery electrolyte (containing ethyl methyl carbonate EMC: diethyl carbonate DEC: ethylene carbonate EC = 1:1:1) into a 1.5 ml open bottle with a bottle mouth diameter of 5 mm. Place the bottle on the center line of the air inlet of the intermittent pipeline gas sampling device, and collect the released substances through intermittent gas extraction for analysis. Monitor the peak height of the characteristic peak within 3.8 to 5.5 ms.

[0065] in:

[0066] The inner diameter of the air intake is 20 mm;

[0067] The air flow rate is 100 liters per minute;

[0068] The pumping speed at the air inlet is 3 m / s;

[0069] The intermittent start-up time of the ducted exhaust fan is 30 seconds, and the shut-off time is 5 seconds.

[0070] The average cumulative peak height of the 3.9ms characteristic peak is 15V (cumulative 42 spectra, 5 seconds).

[0071] Table 1. Migration time and ratio of substances released from lithium battery electrolyte in air.

[0072]

[0073] Note: The ratio of migration time is the characteristic peak migration time of substances released from lithium battery electrolyte in air / acetone migration time.

[0074] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the implementation. The scope of protection of the present invention should be determined by the scope defined in the claims. Other variations or modifications can be made based on the above description. Obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A method for intermittent collection and analysis of substances released by lithium battery electrolytes in air, characterized in that: An intermittent pipeline air extraction sampling device is used to extract substances released from the air by lithium battery electrolyte in the environment. The intermittent pipeline air extraction sampling device includes an inlet pipe, an outlet pipe, and a pipeline exhaust fan. One end of the inlet pipe is an air inlet, one end of the outlet pipe is connected to the pipeline exhaust fan, and the other end is connected to the inlet pipe. An insertion port is provided on the inlet pipe. The method includes the following steps: (1) Using ion mobility spectrometry, in positive ion mode, ethanol is used as a dopant. The pipeline exhaust fan is turned on intermittently, and the lithium battery electrolyte is extracted from the environment through the air inlet pipe and released into the air outlet pipe. (2) The sample is injected through the inlet of the ion mobility spectrometer to obtain the spectrum of peak height versus migration time and the spectrum of characteristic peak height versus continuous analysis time.

2. A method for intermittent collection and analysis of substances released by lithium battery electrolytes in air according to claim 1, characterized in that: The ratio of the characteristic peak migration time of lithium battery electrolyte to the ethanol migration time is 1.03-1.

45.

3. A method for intermittent collection and analysis of substances released by lithium battery electrolytes in air according to claim 1, characterized in that: The inner diameter of the inlet of the ion mobility spectrometer is 20-50 mm, the pumping flow rate is 100-900 liters / minute, and the pumping speed at the inlet is 3-23 m / s.

4. The method for intermittent collection and analysis of substances released by lithium battery electrolytes in air according to claim 1, characterized in that: The intermittent pipeline air extraction sampling device also includes a windproof cap, which is connected to the exhaust port of the pipeline exhaust fan.

5. The method for intermittent collection and analysis of substances released by lithium battery electrolytes in air according to claim 1, characterized in that: The ratio of intermittent on-time to off-time of a ducted exhaust fan is 1 to 6:

1.

6. The method for intermittently collecting and analyzing substances released from lithium battery electrolyte in the air according to claim 1, characterized in that: The intermittent start-up time of the ducted exhaust fan is 5-30 seconds, and the shut-off time is 5 seconds.

7. The method for intermittently collecting and analyzing substances released from lithium battery electrolyte in the air according to claim 1, characterized in that: The intermittent pipeline air extraction sampling device has 1-6 air inlet pipes.

8. The method for intermittently collecting and analyzing substances released from lithium battery electrolyte in the air according to claim 1, characterized in that: The intermittent pipeline air extraction sampling device also includes a power supply battery, which is connected to a pipeline exhaust fan. The power supply battery is a solar panel or an energy storage battery.

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