Soft package battery formation gas production analysis system and method

Abstract

The invention relates to the technical field of battery gas production analysis, and discloses a soft package battery formation gas production analysis system and method.The soft package battery formation gas production analysis system comprises a formation device and a gas collection bottle, the formation device is connected with a soft package battery, and the gas collection bottle is connected with a gas bag of the soft package battery, a gas chromatograph-mass spectrometer and a vacuumizing unit through gas guide pipes with electromagnetic valves; the vacuumizing unit is used for vacuumizing the system, and analysis and detection of the formation device on gas production of the soft package battery under different formation steps are realized through opening and closing of an electromagnetic valve; according to the soft package battery formation gas production analysis system, the steps of formation, gas collection and gas analysis are combined, gas of each process step can be rapidly collected, and meanwhile, gas components of each process step can be efficiently analyzed; by arranging the first electromagnetic valve, the second electromagnetic valve and the third electromagnetic valve, the system can integrate the steps of vacuumizing, formation gas production, gas collection and gas analysis through the PLC control unit.

Description

Technical Field

[0001] The present invention relates to the technical field of battery gas production analysis, and in particular to a system and method for analyzing gas production during formation of a soft-pack battery. Background Art

[0002] Lithium-ion batteries have attracted widespread attention due to their high energy density and long cycle life. In the actual work of lithium-ion batteries, the most important one is the solid electrolyte interface film (including the positive and negative solid electrolyte interface films). In the manufacturing process of lithium batteries, formation is an extremely important step. During the formation, a passivation layer is formed on the surface of the negative electrode, namely the solid electrolyte interface film SE I film. When the SE I film is formed, a large number of negative reactions are accompanied, and gases including CO2, N2, CH4, C2H6, C2H4, etc. are produced. The amount of these gases produced directly affects the charge and discharge reaction of the battery and the quality of the SE I film. The quality of the film also directly affects the electrochemical properties of the battery, such as cycle life, self-discharge performance, and safety. Different lithium battery materials have different gas production amounts during the formation process, and the end time of gas production is also different. Not only are the SE I films formed different, but it also has a great impact on the subsequent processes. Therefore, the study of formation gas production is of great significance.

[0003] The utility model patent with application number 202221989592.0 discloses a device for detecting gas production of soft-pack batteries, but it is unable to simply, quickly and efficiently analyze the composition of the gas generated in each process step.

[0004] The invention patent with application number 202110546279.3 discloses a device and method for analyzing the gas production components of a battery by electrochemical-gas chromatography-mass spectrometry. The electrochemical workstation can control the voltage, current, battery capacity, time control and other electrical signals during the operation of the battery box, but it is not used in conjunction with a formation device, and cannot timely analyze the gas production components and gas production rate of each stage of the formation process. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a soft-pack battery formation gas analysis system, which can quickly collect the gas in each process step by setting up a formation device, a gas chromatograph-gas spectrometer, and a gas collecting bottle, and can efficiently analyze the gas composition of each process step.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] In a first aspect, a soft-pack battery formation gas production analysis system includes a formation device and a gas collecting bottle, wherein the formation device is connected to the soft-pack battery, and the gas collecting bottle is respectively connected to an airbag bag of the soft-pack battery, a gas spectrometer, and a vacuum unit through a gas duct with an electromagnetic valve, wherein the vacuum unit is used to vacuum the system, and the electromagnetic valve is switched to enable the formation device to analyze and detect the gas production in different formation steps of the soft-pack battery.

[0008] As a further implementation, a PLC control unit is also included, and the PLC control unit is connected to the formation device, the vacuum unit and the solenoid valve.

[0009] As a further implementation, the gas collecting bottle is connected to the airbag bag via a gas conduit with a first solenoid valve.

[0010] As a further implementation, the gas collecting bottle is connected to the vacuum unit via a gas conduit with a second solenoid valve.

[0011] As a further implementation, the vacuum unit includes a vacuum pump.

[0012] As a further implementation, the gas collecting bottle is connected to the gas spectrometer-gas spectrometer via a gas conduit with a third solenoid valve.

[0013] As a further implementation, the gas chromatography-mass spectrometer includes an injection port, a gas chromatography system and a mass spectrometry system, and the injection port is connected to the gas outlet port of the third solenoid valve through an injection needle.

[0014] In a second aspect, a method for analyzing gas production during formation of a soft-pack battery is provided, using any of the above-described soft-pack battery gas production analysis systems, comprising the following steps:

[0015] The battery cells of the soft-pack battery are connected to the formation device, and the first solenoid valve and the third solenoid valve are closed through the PLC control unit, and the second solenoid valve and the vacuum unit are opened to evacuate the gas collecting bottle; for different formation steps, the vacuum unit and the second solenoid valve are closed, the first solenoid valve is opened during gas production, and the third solenoid valve is opened during analysis, so that the gas enters the gas collecting bottle during formation and gas production, and the gas enters the gas collection bottle for gas chromatography-mass spectrometry analysis during gas analysis.

[0016] As a further implementation method, a total ion current diagram is obtained by gas chromatography-mass spectrometry, and the composition and structure of the product are identified by spectral analysis, mass spectrum library and manual analysis.

[0017] As a further implementation method, the content of the main charge and discharge products is determined by using an area normalization method.

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

[0019] 1. The soft-pack battery formation gas production analysis system of the present invention realizes the combination of a formation device, a gas collection device and a gas analysis device, and by setting a gas conduit and a corresponding solenoid valve and controlling it using a PLC control unit, the gas of each process step can be quickly collected, and the gas composition of each process step can be efficiently analyzed.

[0020] 2. The present invention provides a first solenoid valve, a second solenoid valve and a third solenoid valve, and can realize a system integrating vacuuming, gas production, gas collection and gas analysis steps through a PLC control unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0022] Figure 1 It is a schematic diagram of the overall structure of the soft-pack battery formation gas production analysis system in an embodiment of the present invention.

[0023] In the figure: the distances or sizes between parts are exaggerated to show the positions of various parts, and the schematic diagram is for reference only.

[0024] Among them: 2. air bag, 30. first solenoid valve, 31. second solenoid valve, 32. third solenoid valve, 4. gas collecting bottle, 5. gas spectrometer, 6. vacuum pump, 7. gas conduit, 8. formation device. DETAILED DESCRIPTION

[0025] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0026] Embodiment 1

[0027] In a typical embodiment of the present invention, reference is made to Figure 1 As shown, a soft-pack battery formation gas production analysis system includes a formation device and a gas collecting bottle 4, wherein the formation device 8 is connected to the soft-pack battery, and the gas collecting bottle is respectively connected to the air bag 2 of the soft-pack battery, the gas spectrometer 5, and the vacuum unit through a gas conduit with a solenoid valve, and the vacuum unit is used to vacuum the system. The PLC control unit is connected to the formation device, the vacuum unit and the solenoid valve, and the PLC control unit controls the switch of the solenoid valve to realize the formation device 8 to analyze and detect the gas production under different formation steps of the soft-pack battery.

[0028] like Figure 1As shown, the gas collecting bottle 4 is connected to the airbag bag 2 through a gas conduit 7 with a first solenoid valve 30, the gas collecting bottle is connected to the vacuum unit through a gas conduit 7 with a second solenoid valve 31, and the gas collecting bottle 4 is connected to the gas spectrometer 5 through a gas conduit 7 with a third solenoid valve 32. The vacuum unit includes a vacuum pump 6, and the gas spectrometer includes an injection port, a gas chromatography system, and a mass spectrometer system, and the injection port is connected to the gas outlet port of the third solenoid valve through an injection needle.

[0029] In this embodiment, the airbag bag 2 of the soft-pack battery is used to collect the gas generated by the formation device during the formation of the battery cell; the gas conduit 7 is used to transport the produced gas, and is preferably a glass conduit or a PVC conduit, and the conduit is pressure-resistant and corrosion-resistant.

[0030] In this embodiment, the gas collecting bottle 4 is used to collect gas, preferably a glass bottle, a steel bottle lined with polytetrafluoroethylene, which has pressure resistance, corrosion resistance and good airtightness functions; the vacuum pump 6 is used to draw negative pressure, preferably a diaphragm pump, a water ring pump and a reciprocating pump, and is equipped with a pressure gauge. By opening the solenoid valve 31, the gas collecting bottle can be vacuumed.

[0031] The first solenoid valve 30, the second solenoid valve 31 and the third solenoid valve 32 are used to control the inlet and outlet of the gas. The PLC control unit is connected to the formation device 8, the solenoid valve, and the gas spectrometer-gas spectrometer 5 to control the linkage of related equipment, so that the system integrates the steps of vacuuming, formation, gas production, gas collection, and analysis, and can analyze the gas composition of different steps.

[0032] The gas chromatography-mass spectrometer 5 of this embodiment is used for analyzing and detecting the gas generated by the formation. The preferred test conditions of the gas chromatography are: the chromatographic column is a polar or non-polar capillary column with a length of 30-60m, a diameter of 0.25-0.53mm and a film thickness of 0.3-50μm; the carrier gas is 99.999% high-purity helium;

[0033] PLC injection time is 50-100ms, column flow rate is 1-1.5mL / min; split injection split ratio is 2-5:1; injection port temperature is 230-280℃; column temperature heating program: 5-50℃ for 2-10min, increase to 150-200℃ at 5-10℃ / min, and hold for 5-15min.

[0034] The test conditions of mass spectrometry are: the electron energy of the EI source ionization source is 70eV, the temperature of the quadrupole is 150-200℃, the temperature of the ion source is 230-280℃, the full scan mode, the scanning range is 15-500u; the interface temperature is 230-250℃. The total ion flow chart is obtained, and the composition and structure of the product are identified through spectrum analysis, mass spectrum library and manual analysis; the content of the main charge and discharge products is determined by the area normalization method.

[0035] Embodiment 2

[0036] In a typical embodiment of the present invention, reference is made to Figure 1 As shown, a method for analyzing gas production during formation of a soft-pack battery, using the soft-pack battery gas production analysis system described in Example 1, includes the following steps:

[0037] The battery cells of the soft-pack battery are connected to the formation device, and the first solenoid valve 30 and the third solenoid valve 32 are closed through the PLC control unit, and the second solenoid valve 31 and the vacuum unit are opened to evacuate the gas collecting bottle 4; for different formation steps, the vacuum unit and the second solenoid valve 31 are closed, the first solenoid valve 30 is opened during gas production, and the third solenoid valve 32 is opened during analysis, so that the gas enters the gas collecting bottle 4 during formation and gas production, and enters the gas chromatograph-gas spectrometer 5 from the gas collecting bottle for analysis during gas analysis.

[0038] Specifically, a formation reaction is performed on the lithium-ion battery cell in a certain formation process, the formation device is connected to the PLC, and the gas generated in the formation process is tested online; the formation system when the lithium-ion battery cell is formed is: the first standing for 5-30 minutes under a 45°C environment, charging at a constant current of 0.02-0.05C for a specified time in the first formation stage, and standing for 5-30 minutes; charging at a constant current of 0.1-0.5C for a specified time in the second formation stage; standing for 5-30 minutes, and finally charging at a constant current and constant voltage of 0.5-1C to a specified cut-off voltage in the third formation stage, and using a cut-off current of 0.02-0.05C to complete the formation.

[0039] The PLC is connected to the solenoid valve, which is consistent with the process control of the formation system. During the initial resting, the first solenoid valve 30 is closed, the third solenoid valve 32 is closed, the second solenoid valve 31 is opened, and the vacuum pump 6 is turned on to evacuate the gas collecting bottle 4, so that the gas collecting bottle 4 is in a vacuum state. During the second resting, the first solenoid valve 30 is opened, the vacuum pump 6 and the third solenoid valve 32 are closed, and the gas generated in the first formation stage is in the airbag bag 2 and introduced into the gas collecting bottle 4 through the gas conduit 7 for collection. After that, the third solenoid valve 32 is opened, and the gas in the gas collecting bottle 4 is extracted through the injection needle of the gas spectrometer. The gas enters the gas spectrometer, and the program analyzes and detects the gas composition.

[0040] The action procedures in the second formation stage and the third formation stage 3 are consistent with the steps of the first formation stage. The PLC control unit control system first evacuates the gas, then generates gas, collects the gas through the gas collecting bottle, and finally extracts the gas in the gas collecting bottle 4 through the sampling needle of the gas spectrometer. The gas enters the gas spectrometer, and the program analyzes and detects the gas composition, which will not be repeated here.

[0041] The gas spectrometer 5 is used as a gas separation and detection system. The gas generated by the battery box is separated and the gas type and content are qualitatively and quantitatively analyzed by gas spectrometer 5. It includes an injection port, a gas chromatography system and a mass spectrometer system, which are used to display and record the composition, content and change of each channel sample over time, and obtain mass spectrum data for further analysis. The injection port is connected to the gas outlet port of the third electromagnetic valve 32 through an injection needle. When the gas collecting bottle 4 collects the gas generated in the first formation stage, the first electromagnetic valve 30 and the second electromagnetic valve 31 are closed, the third electromagnetic valve 32 is opened, and the injection needle extracts the gas in the gas collecting bottle 4. The gas enters the gas spectrometer, and the program analyzes and detects the gas composition. After the analysis of the first formation stage is completed, the vacuum unit is used to evacuate again, and the formation, gas production, gas collection and analysis of the subsequent formation stage are carried out.

[0042] For the preparation of lithium-ion batteries: add positive electrode materials, conductive agents (Super P), carbon tubes (CNTs) and polyvinylidene fluoride (PVDF) to N-methylpyrrolidone (NMP) according to the specified mass ratio, mix them evenly to form a slurry, apply the slurry on the aluminum foil current collector, dry and punch to obtain the positive electrode sheet. Add graphite, conductive agent (Super P), single-walled carbon tubes (SWCNTs), sodium carboxymethyl cellulose (CMC) and styrene-butadiene rubber latex (SBR) to deionized water according to the specified mass, stir and mix them evenly, apply the slurry on the copper foil current collector, bake and dry and punch to obtain the negative electrode sheet. Stack the separator, negative electrode sheet and positive electrode sheet in a "Z" shape to obtain a lithium-ion battery.

[0043] Specific implementation method:

[0044] Lithium-ion battery cell formation and collection system: stand at 45°C for 30 minutes, turn on the PLC control unit to control the first solenoid valve 30 and the third solenoid valve 32 to close, open the second solenoid valve 31 and the vacuum pump 6, and the gas collecting bottle 4 is in a vacuum state; the first formation stage is charged at a constant current of 0.02C for 180 minutes, and there is a certain amount of gas in the airbag bag 2. At this time, the first solenoid valve 30 is opened through the PLC control unit, and the vacuum pump 6 and the second solenoid valve 31 are closed. The gas in the airbag bag 2 enters the gas collecting bottle 4 through the gas duct 7. The second formation stage and the third formation stage are consistent with the procedure of collecting the first formation stage, and will not be repeated.

[0045] Gas detection: When the gas generated in the first formation stage is collected by the gas collecting bottle 4, the first solenoid valve 30 and the second solenoid valve 31 are closed, the third solenoid valve 32 is opened, and the injection needle extracts the gas in the gas collecting bottle 4, and the gas enters the gas spectrometer-gas spectrometer, and the program analyzes and detects the gas components. The test conditions of gas chromatography are as follows: the chromatographic column is Agile ent G3591-80013G3591-80013, with a size of 30m×0.32mm×3μm; the carrier gas is 99.999% high-purity helium; the column flow rate is 1mL / min; the split injection split ratio is 5:1; the injection port temperature is 250℃; the column temperature heating program: heat up to 280℃ at 5℃ / min and keep for 5min;

[0046] The test conditions of mass spectrometry are: the electron energy of the EI source ionization source is 70eV, the temperature of the quadrupole is 150℃, the temperature of the ion source is 230℃, the full scan mode, the scanning range is 15-500u; the interface temperature is 250℃. The total ion flow chart is obtained, and the composition and structure of the product are identified through spectrum analysis, mass spectrum library and manual analysis; the content of the main charge and discharge products is determined by the area normalization method.

[0047] The soft-pack battery formation gas production analysis system of this embodiment realizes the combined use of a formation device, a gas collection device and a gas analysis device, and by setting a gas duct and a corresponding solenoid valve and controlling it using a PLC control unit, the gas of each process step can be quickly collected and the gas composition of each process step can be efficiently analyzed.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A soft pack battery formation gas production analysis system, characterized in that: The invention comprises a formation device and a gas collecting bottle. The formation device is connected to a soft-pack battery. The gas collecting bottle is respectively connected to an air bag of the soft-pack battery, a gas spectrometer-gas spectrometer and a vacuum unit through a gas conduit with an electromagnetic valve. The vacuum unit is used to vacuum the system. The formation device can analyze and detect the gas produced by the soft-pack battery in different formation steps by switching the electromagnetic valve.

2. A soft pack battery formation gas analysis system according to claim 1, characterized in that: It also includes a PLC control unit, which is connected to the formation device, the vacuum unit and the solenoid valve.

3. A soft pack battery formation gas production analysis system according to claim 1, characterized in that: The gas collecting bottle is connected to the air bag through a gas conduit with a first solenoid valve.

4. A soft pack battery formation gas production analysis system according to claim 3, characterized in that: The gas collecting bottle is connected to the vacuum unit through a gas conduit with a second solenoid valve.

5. A soft pack battery formation gas production analysis system according to claim 4, characterized in that: The vacuum unit includes a vacuum pump.

6. A soft pack battery formation gas production analysis system according to claim 4, characterized in that: The gas collecting bottle is connected to the gas spectrometer-gas spectrometer via a gas conduit with a third solenoid valve.

7. A soft pack battery formation gas production analysis system according to claim 6, characterized in that: The gas chromatography-mass spectrometer comprises an injection port, a gas chromatography system and a mass spectrometry system. The injection port is connected to the gas outlet port of the third electromagnetic valve through an injection needle.

8. A method for analyzing gas production during formation of a soft-pack battery, characterized in that: The soft pack battery formation gas production analysis system as claimed in claim 7 comprises the following steps: The battery cells of the soft-pack battery are connected to the formation device, and the first solenoid valve and the third solenoid valve are closed through the PLC control unit, and the second solenoid valve and the vacuum unit are opened to evacuate the gas collecting bottle; for different formation steps, the vacuum unit and the second solenoid valve are closed, the first solenoid valve is opened during gas production, and the third solenoid valve is opened during analysis, so that the gas enters the gas collecting bottle during formation and gas production, and the gas enters the gas collection bottle for gas chromatography-mass spectrometry analysis during gas analysis.

9. A method for analyzing gas production during formation of a soft-pack battery according to claim 8, characterized in that: The total ion current was obtained by gas chromatography-mass spectrometry, and the composition and structure of the product were identified by spectral analysis, mass spectrometry library and manual analysis.

10. A method for analyzing gas generation during formation of a soft-pack battery according to claim 9, characterized in that: The content of the main charge and discharge products is determined by the area normalization method.

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