Method and system for testing gas production of battery cell

Abstract

The invention provides a test method and a test system for gas production of a battery cell. The method for testing the gas production of the battery cell comprises the following steps: firstly, providing a to-be-tested positive plate and a to-be-tested negative plate, respectively sealing and packaging the to-be-tested positive plate and the to-be-tested negative plate in a preset container filled with electrolyte, and storing the preset container in a preset temperature environment; secondly, gas generated by the to-be-measured positive plate and the to-be-measured negative plate in the corresponding preset containers is collected, and finally gas analysis is conducted on the gas generated by the to-be-measured positive plate and the gas generated by the to-be-measured negative plate, so that independent measurement and analysis of gas generation components stored in the positive plate and the negative plate and the relative content are achieved. The accuracy and the comparability of the cell gas production test are improved, and a reliable basis is provided for cell design improvement and production process adjustment.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a method and system for testing gas production of a battery cell. Background Art

[0002] With the rapid development of portable electronic devices, electric vehicles and energy storage systems, lithium-ion batteries have been widely used in various energy consumption scenarios due to their high energy density, good cycle life and high operating voltage, becoming one of the current mainstream secondary power sources.

[0003] Gas generation is common during the production, storage, transportation, and use of lithium-ion batteries. Because batteries are typically enclosed, the continuous accumulation of gas can lead to increased pressure within the cell, potentially causing bulging, seal failure, and even, in extreme cases, thermal runaway. Therefore, studying the gas generation mechanisms of lithium-ion batteries under different conditions and their impact on cell performance, as well as developing appropriate preventive and improvement measures, is of great practical significance for improving battery safety and reliability. Summary of the Invention

[0004] The embodiments of the present application provide a method and system for testing gas production of a battery cell, which are used to solve or at least partially solve the deficiencies of the above-mentioned background technology.

[0005] In a first aspect, an embodiment of the present application provides a method for testing gas generation of a battery cell, comprising:

[0006] Provide the positive electrode sheet and the negative electrode sheet to be tested;

[0007] The positive electrode sheet to be tested and the negative electrode sheet to be tested are respectively sealed and packaged in a preset container filled with electrolyte, and the preset containers are stored in a preset temperature environment;

[0008] Collecting the gases generated by the positive electrode sheet to be tested and the negative electrode sheet to be tested in the corresponding preset containers respectively;

[0009] Gas analysis is performed on the gases generated by the positive electrode sheet to be tested and the negative electrode sheet to be tested respectively.

[0010] In one embodiment, providing a positive electrode sheet to be tested and a negative electrode sheet to be tested includes:

[0011] Acquire multiple battery cells to be tested, and regulate different battery cells to be tested to at least two target states of charge by charging and discharging;

[0012] The plurality of cells to be tested are disassembled, and the positive electrode sheets and the negative electrode sheets in the cells to be tested are separated respectively, so as to obtain the plurality of positive electrode sheets to be tested and the plurality of negative electrode sheets to be tested with different states of charge.

[0013] In one embodiment, providing a positive electrode sheet to be tested and a negative electrode sheet to be tested includes:

[0014] Processing a plurality of unformed battery cells according to at least two different formation processes to obtain a plurality of battery cells to be tested;

[0015] The plurality of cells to be tested are disassembled and the positive and negative electrode sheets in the plurality of cells to be tested are separated to obtain a plurality of positive electrode sheets to be tested and a plurality of negative electrode sheets to be tested having different formation processes.

[0016] In one embodiment, the step of sealing the positive electrode sheet to be tested and the negative electrode sheet to be tested in predetermined containers filled with electrolyte comprises:

[0017] Placing the positive electrode sheet to be tested and the negative electrode sheet to be tested into the preset containers respectively;

[0018] injecting electrolyte into the preset container;

[0019] The preset container filled with the electrolyte is sealed.

[0020] In one embodiment, sealing the preset container into which the electrolyte is injected comprises:

[0021] The air in the preset container is exhausted, and the opening of the preset container is heat-sealed; wherein the heat-sealing temperature is greater than or equal to 150° C. and less than or equal to 180° C.; and the heat-sealing time is greater than or equal to a preset time.

[0022] In one embodiment, the preset temperature is greater than or equal to 75° C. and less than or equal to 85° C.;

[0023] And / or, the storage time at the preset temperature is greater than or equal to 12 hours and less than or equal to 168 hours.

[0024] In one embodiment, the preset container is an aluminum-plastic film bag, and the thickness of the preset container is greater than or equal to 96 microns and less than or equal to 115 microns.

[0025] In one embodiment, the method for testing gas generation of a battery cell further includes:

[0026] Capturing images of the positive electrode sheet to be tested and the negative electrode sheet to be tested;

[0027] Image recognition is performed on the picture to obtain characteristic information of the positive electrode sheet to be tested and the negative electrode sheet to be tested, wherein the characteristic information includes at least one of the surface morphology characteristics, particle crack characteristics, porosity change characteristics, or deposition characteristics of electrolyte decomposition products of the positive electrode sheet to be tested and the negative electrode sheet to be tested.

[0028] In one embodiment, the method for testing gas generation of a battery cell further includes:

[0029] According to the characteristic information and / or the gas production measurement result, the performance impact information of the positive electrode sheet to be tested and the negative electrode sheet to be tested under at least two target charge states or at least two different formation processes is analyzed and determined.

[0030] In a second aspect, the present invention provides a battery cell gas production test system, comprising:

[0031] The pre-set container is used to seal and package the positive electrode sheet to be tested and the negative electrode sheet to be tested respectively, and is filled with electrolyte;

[0032] A temperature control device, used to place the preset container and keep the preset container in a preset temperature environment;

[0033] A collecting device, used to collect the gas generated by the positive electrode sheet to be tested and the negative electrode sheet to be tested in the corresponding preset containers;

[0034] The analyzing device is used to perform gas analysis on the gas generated by the positive electrode sheet to be tested and the negative electrode sheet to be tested respectively, and obtain the gas production measurement results of the battery cells corresponding to the positive electrode sheet to be tested and the negative electrode sheet to be tested.

[0035] Beneficial effects of the embodiments of the present application: The embodiments of the present application provide a method and system for testing gas production of battery cells, the method for testing gas production of battery cells comprising providing a positive electrode sheet to be tested and a negative electrode sheet to be tested; sealing and encapsulating the positive electrode sheet to be tested and the negative electrode sheet to be tested in preset containers injected with electrolyte, respectively, and storing the preset containers in a preset temperature environment; collecting the gases generated by the positive electrode sheet to be tested and the negative electrode sheet to be tested in the corresponding preset containers; performing gas analysis on the gases generated by the positive electrode sheet to be tested and the negative electrode sheet to be tested, respectively, thereby achieving independent measurement and analysis of the gas production components and relative contents stored in the positive electrode sheet and the negative electrode sheet, improving the accuracy and comparability of the battery cell gas production test, and providing a reliable basis for battery cell design improvement and production process adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solution in this embodiment, the following is a brief introduction to the drawings required for the description of the embodiment. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 Flowchart of the method for testing gas production of a battery cell provided in an embodiment of the present application;

[0038] Figure 2A data graph showing the gas production measurement result rate of a battery cell corresponding to the battery cell gas production test method provided in Example 1 of the present application;

[0039] Figure 3 A data graph showing the gas production measurement result rate of a battery cell corresponding to the battery cell gas production test method provided in Example 2 of the present application;

[0040] Figure 4 This is a schematic diagram of the structure of the battery cell gas production test system provided in an embodiment of the present application.

[0041] Description of reference numerals:

[0042] 1-Battery cell gas production test system; 11-Preset container; 12-Temperature control device; 13-Collection device; 14-Analysis device. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present application, and are not used to limit the present application. In the present application, unless otherwise specified, the directional words used, such as "upper" and "lower", generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; and "inside" and "outside" refer to the outline of the device.

[0044] See also Figure 1 In one embodiment, the method for testing gas production of the battery cell includes:

[0045] Step S10: providing a positive electrode sheet to be tested and a negative electrode sheet to be tested.

[0046] Specifically, step S10 includes:

[0047] Step S11A: Obtain multiple battery cells to be tested, and adjust different battery cells to at least two target states of charge through charging and discharging; wherein the target states of charge include but are not limited to one of 0% SOC, 25% SOC, 50% SOC, 75% SOC and 100% SOC, so as to simulate different power states of the battery cells during actual use.

[0048] In step S11A, the positive electrode sheets, negative electrode sheets and diaphragm materials of the multiple battery cells to be tested are all derived from the same raw material batch, and are processed and formed with the same process flow on the same production line and in a similar time period to ensure consistency and comparability in material composition and process conditions between samples; further, the multiple battery cells to be tested are of the same model, and are pretreated using the same formation process to avoid interference with subsequent gas production behavior due to model differences or process deviations, thereby improving the accuracy and reference value of the test results.

[0049] It should be noted that this embodiment does not impose any specific restrictions on the charging and discharging methods of the battery cell to be tested, as well as the specific processes and parameters of the formation process; wherein, the charging and discharging can adopt constant current, constant voltage or constant current-constant voltage modes, and the specific parameters can be set according to the battery cell type, capacity and target state of charge (SOC) requirements; the formation process can adopt normal temperature formation, high temperature formation and multi-stage gradient formation modes.

[0050] It can be understood that in this embodiment, the multiple battery cells to be tested are of the same model, and the different battery cells to be tested are respectively adjusted to at least two target charge states through charging and discharging, thereby achieving a systematic study and comparative analysis of the electrode gas production characteristics under different target charge states, providing experimental basis and data support for subsequent battery cell design optimization, electrochemical behavior mechanism analysis and safety assessment.

[0051] Step S12A: disassembling the plurality of cells to be tested, separating the positive electrode sheets and the negative electrode sheets in the cells to be tested, and obtaining the plurality of positive electrode sheets to be tested and the plurality of negative electrode sheets to be tested with different states of charge.

[0052] Specifically, in step S12A, after the battery cell to be tested is disassembled, the positive electrode sheet and the negative electrode sheet in the battery cell are taken out respectively, and a hole extractor is used to take out sample sheets of the same size from the positive electrode sheet and the negative electrode sheet respectively, so that the samples have good comparability in size and morphology; wherein, the positive electrode sheet after sampling is the positive electrode sheet to be tested, and the negative electrode sheet after sampling is the negative electrode sheet to be tested.

[0053] Furthermore, the sampling positions of different cells to be tested can be kept consistent, thereby improving the comparability and representativeness of subsequent gas production test results; and the positive electrode sheet to be tested and the negative electrode sheet to be tested can be placed in sealed bags respectively to achieve sealed storage.

[0054] Step S20: Seal and package the positive electrode sheet to be tested and the negative electrode sheet to be tested in preset containers filled with electrolyte, respectively, and store the preset containers in a preset temperature environment.

[0055] Specifically, step S20 includes:

[0056] Step S21A: placing the positive electrode sheet to be tested and the negative electrode sheet to be tested into the preset containers respectively.

[0057] Specifically, in step S21A, in a vacuum environment with a dew point less than -40°C, the positive electrode sheet to be tested and the negative electrode sheet to be tested with different charge states are respectively placed in the preset containers to avoid contact between the electrode sheets and moisture or oxygen in the air, prevent non-target reactions, and ensure the accuracy and controllability of the test conditions.

[0058] The preset container is a container made of a material with good sealing, chemical stability and heat resistance, so as to ensure that the internal environment is stable and leak-free during the subsequent high-temperature storage process, and avoid the authenticity and comparability of the gas production behavior being affected by external interference; wherein, the preset container can be an aluminum-plastic film bag, and each of the preset containers contains only one type of electrode, thereby realizing the test of the independent gas production behavior of the positive and negative electrodes under different conditions.

[0059] Furthermore, the positive electrode sheet to be tested and the negative electrode sheet to be tested can be placed in pockets of aluminum-plastic film bags respectively, and sealed under a vacuum environment to achieve sealed storage of the positive electrode sheet to be tested and the negative electrode sheet to be tested, so as to prevent the components in the air from affecting the electrode materials.

[0060] The thickness of the preset container is greater than or equal to 96 microns and less than or equal to 115 microns. While achieving the airtightness and mechanical strength of the package, it also takes into account flexibility and heat sealing performance, thereby maintaining the structural stability and sealing of the preset container during subsequent high-temperature storage, so that the reaction behavior between the electrode sheet and the electrolyte proceeds in a relatively stable and controlled environment.

[0061] It should be noted that, in the specific implementation process, the step S20 also includes: placing the fresh positive electrode sheet to be tested, the fresh negative electrode sheet to be tested and the electrolyte to be tested into the preset container respectively; wherein, the fresh positive electrode sheet to be tested is the original positive electrode sheet that has not undergone any charge and discharge cycle treatment, the fresh negative electrode sheet to be tested is the original negative electrode sheet that has not undergone any charge and discharge cycle treatment, and the electrolyte to be tested has exactly the same formula composition as the electrolyte that actually reacts with the electrode sheet in subsequent tests.

[0062] Step S22A: injecting electrolyte into the preset container.

[0063] Specifically, in step S22A, a predetermined volume of electrolyte can be injected into the preset container encapsulating the positive electrode sheet to be tested or the negative electrode sheet to be tested by using a pipette gun or an automatic liquid dispensing device; wherein, an equal amount of electrolyte with the same formula is injected into each of the preset containers, so that different samples react under the same electrolyte, thereby ensuring the consistency of experimental conditions and the comparability of test results; the injection amount of the electrolyte can be set according to the size of the electrode sheet, the load amount and the subsequent test requirements, thereby forming an effective electrode-electrolyte contact interface to simulate the chemical reaction conditions under the actual battery cell environment.

[0064] Furthermore, step S22A also includes: injecting electrolyte into a preset container storing the fresh positive electrode sheet to be tested, injecting electrolyte into a preset container storing the fresh negative electrode sheet to be tested, and injecting electrolyte into a preset container storing the electrolyte to be tested; wherein, an equal amount of electrolyte with the same formula is injected into each of the preset containers.

[0065] Step S23A: sealing the preset container filled with electrolyte.

[0066] Specifically, in step S23A, the interior of the preset container is evacuated to discharge the air inside the preset container, so that the interior of the preset container is in a vacuum or low-oxygen environment to reduce gas interference and simulate actual working conditions; then, the opening of the preset container is heat-sealed to achieve effective sealing.

[0067] The temperature of the heat sealing treatment is greater than or equal to 150°C and less than or equal to 180°C, and the heat sealing time is greater than or equal to a preset time, which is greater than 6 seconds. The specific heat sealing parameters can be set according to the performance of the aluminum-plastic film bag material used and the sealing effect requirements to ensure the sealing strength and airtightness of the preset container after sealing, and avoid leakage or external gas infiltration during subsequent storage, which may affect the accuracy and reliability of the gas production results.

[0068] Step S24A: After the preset container is packaged, the preset container is placed in a constant temperature box for storage, wherein the constant temperature box has the preset temperature.

[0069] Specifically, in step S24A, the preset temperature of the constant temperature box is greater than or equal to 75°C and less than or equal to 85°C, and the storage time at the preset temperature is greater than or equal to 12 hours and less than or equal to 168 hours; wherein, the preset temperature and storage time can be set according to the battery cell application scenario or accelerated test requirements, for example, the preset container is stored in a constant temperature box at 85±1°C for 24 hours to accelerate the reaction process between the electrode material and the electrolyte under controllable conditions, thereby more significantly characterizing the gas production behavior of different electrode sheets under different charge states.

[0070] It should be noted that the gas production in the battery cell is mostly caused by side reactions between the positive electrode sheet, the negative electrode sheet and the electrolyte. For example, the positive electrode material (such as ternary materials or lithium manganese oxide under high voltage) decomposes to produce oxygen, the negative electrode (such as graphite) surface reacts with the solvent or LiPF6 salt in the electrolyte to produce combustible gas, and the electrolyte itself decomposes thermally. The activation energy of the above side reactions is relatively high, and the reaction rate is slow at room temperature. However, when the temperature rises, the molecular thermal motion intensifies and the reaction rate increases significantly.

[0071] It can be understood that this embodiment sets the preset temperature to be greater than or equal to 75°C and less than or equal to 85°C, and the storage time at the preset temperature to be greater than or equal to 12 hours and less than or equal to 168 hours, thereby effectively accelerating the reaction process between the electrode material and the electrolyte, making the gas production behavior more significant, and then simulating the reaction behavior between the electrode material and the electrolyte during the actual operation or aging process of the battery cell, providing stable and controllable experimental conditions for subsequent gas collection and analysis.

[0072] Step S30: collecting the gases generated by the positive electrode sheet to be tested and the negative electrode sheet to be tested in the corresponding preset containers.

[0073] Specifically, in step S30, the gas in each of the preset containers after the constant temperature storage treatment is collected and quantitatively analyzed to obtain gas information generated by the reaction between the electrode material and the electrolyte under different charge states.

[0074] It should be noted that the gas can be collected by puncture sampling, syringe extraction or other trace gas extraction methods suitable for sealed containers, so that the state of the remaining substance in the preset container is not affected during the collection process; wherein, the collected gas can be used for subsequent component analysis or gas production evaluation, thereby providing data support for battery cell process optimization and gas production risk control.

[0075] Furthermore, the step S30 further includes: collecting gases generated by the fresh positive electrode sheet to be tested, the fresh negative electrode sheet to be tested, and the electrolyte to be tested in the corresponding preset containers.

[0076] Step S40: performing gas analysis on the gas generated by the positive electrode sheet to be tested and the negative electrode sheet to be tested respectively.

[0077] Specifically, in step S40, the gas production conditions corresponding to the collected positive electrode sheet to be tested and the collected negative electrode sheet to be tested are analyzed; during the analysis process, the electrode sheet after gas production is connected to an air bag for gas collection, and gas chromatography (GC) and other analytical methods are used to perform component identification and quantitative analysis on the collected gas samples, so as to obtain the types and relative contents of various gases (such as CO2, H2, CH4, C2H4, C2H6, etc.).

[0078] It is understandable that by comparing the gas composition and gas production under different charge conditions, the reaction behavior between the electrode material and the electrolyte and its potential risks can be revealed, providing a reference basis for battery cell design and process optimization; at the same time, independent measurement and analysis of the storage gas production components and relative contents of the positive and negative electrodes can be achieved, thereby improving the accuracy and comparability of the battery cell gas production test and providing a reliable basis for battery cell design improvements and production process adjustments.

[0079] It should be noted that in step S40, gas analysis can also be performed on the gases generated by the positive electrode sheet to be tested, the negative electrode sheet to be tested, the fresh positive electrode sheet to be tested, the fresh negative electrode sheet to be tested, and the electrolyte to be tested, so as to further provide a reference basis for battery cell design and process optimization.

[0080] Furthermore, the battery cell gas production testing method further includes:

[0081] Step S50: collecting images of the positive electrode sheet to be tested and the negative electrode sheet to be tested.

[0082] Specifically, in step S50, a scanning electron microscope (SEM) may be used to capture images of the positive electrode sheet and the negative electrode sheet to be tested to obtain surface microstructure images thereof for analyzing structural changes of the electrodes after high-temperature storage.

[0083] Step S60: performing image recognition on the image to obtain characteristic information of the positive electrode sheet to be tested and the negative electrode sheet to be tested, wherein the characteristic information includes at least one of the surface morphology characteristics, particle crack characteristics, porosity change characteristics, or deposition characteristics of electrolyte decomposition products of the positive electrode sheet to be tested and the negative electrode sheet to be tested.

[0084] Specifically, in step S60, SEM image recognition and analysis can be used to observe whether there are obvious cracks, shedding, morphology collapse or pore blockage on the surface of the electrode particles, so as to further evaluate the structural stability of the electrode material under the action of high-temperature electrolyte and its correlation with gas production behavior.

[0085] Please continue reading Figure 1 In another embodiment, the method for testing gas production of the battery cell includes:

[0086] Step S10: providing a positive electrode sheet to be tested and a negative electrode sheet to be tested.

[0087] Specifically, step S10 includes:

[0088] Step S11B: processing the plurality of unformed cells according to at least two different formation processes to obtain a plurality of cells to be tested; wherein the formation processes may include but are not limited to one of room temperature formation, high temperature formation and multi-stage gradient formation; each of the unformed cells is subjected to only one formation process.

[0089] The positive electrode sheets, negative electrode sheets and diaphragm materials of the multiple unformed battery cells are all derived from the same batch of raw materials, and are processed and formed with the same process flow on the same production line and in a similar time period to ensure consistency and comparability in material composition and process conditions between samples; further, the multiple unformed battery cells are of the same type to avoid interference with subsequent gas production behavior due to model differences or process deviations, thereby improving the accuracy and reference value of the test results.

[0090] Furthermore, the step S11B also includes regulating the different cells to be tested to the same target state of charge by charging and discharging; wherein the target state of charge includes but is not limited to one of 0% SOC, 25% SOC, 50% SOC, 75% SOC and 100% SOC.

[0091] It should be noted that this embodiment does not impose any specific restrictions on the charging and discharging methods of the battery cell to be tested, as well as the specific processes and parameters of the formation process; wherein, the charging and discharging can adopt constant current, constant voltage or constant current-constant voltage modes, and the specific parameters can be set according to the battery cell type, capacity and target state of charge (SOC) requirements; the formation process can adopt normal temperature formation, high temperature formation and multi-stage gradient formation modes.

[0092] It can be understood that in this embodiment, the multiple unformed battery cells are of the same type. By processing the multiple unformed battery cells according to at least two different formation processes, a comparative analysis of the gas production characteristics of the electrode under different formation processes and its impact on the battery cell performance can be achieved, providing experimental basis and data support for subsequent battery cell design optimization, electrochemical behavior mechanism analysis and safety assessment.

[0093] Step S12B: disassembling the plurality of cells to be tested, separating the positive electrode sheets and the negative electrode sheets in the cells to be tested, and obtaining the plurality of positive electrode sheets to be tested and the plurality of negative electrode sheets to be tested with different formation processes.

[0094] Specifically, in step S12A, after the battery cell to be tested is disassembled, the positive electrode sheet and the negative electrode sheet in the battery cell are taken out respectively, and a hole extractor is used to take out sample sheets of the same size from the positive electrode sheet and the negative electrode sheet respectively, so that the samples have good comparability in size and morphology; wherein, the positive electrode sheet after sampling is the positive electrode sheet to be tested, and the negative electrode sheet after sampling is the negative electrode sheet to be tested.

[0095] Furthermore, the sampling positions of different cells to be tested can be kept consistent, thereby improving the comparability and representativeness of subsequent gas production test results; and the positive electrode sheet to be tested and the negative electrode sheet to be tested can be placed in sealed bags respectively to achieve sealed storage.

[0096] Step S20: Seal and package the positive electrode sheet to be tested and the negative electrode sheet to be tested in preset containers filled with electrolyte, respectively, and store the preset containers in a preset temperature environment.

[0097] Specifically, step S20 includes:

[0098] Step S21B: placing the positive electrode sheet to be tested and the negative electrode sheet to be tested into the preset containers respectively.

[0099] Specifically, in step S21B, in a vacuum environment with a dew point less than -40°C, the positive electrode sheet to be tested and the negative electrode sheet to be tested, which have been processed by different formation processes, are respectively placed in the preset containers to avoid contact between the electrode sheets and moisture or oxygen in the air, prevent non-target reactions, and ensure the accuracy and controllability of the test conditions.

[0100] It should be noted that, in the specific implementation process, the step S20 also includes: placing the fresh positive electrode sheet to be tested, the fresh negative electrode sheet to be tested and the electrolyte to be tested into the preset container respectively; wherein, the fresh positive electrode sheet to be tested is the original positive electrode sheet that has not undergone any charge and discharge cycle treatment, the fresh negative electrode sheet to be tested is the original negative electrode sheet that has not undergone any charge and discharge cycle treatment, and the electrolyte to be tested has exactly the same formula composition as the electrolyte that actually reacts with the electrode sheet in subsequent tests.

[0101] Step S22B: injecting electrolyte into the preset container.

[0102] Specifically, in step S22B, a predetermined volume of electrolyte can be injected into the preset container encapsulating the positive electrode sheet to be tested or the negative electrode sheet to be tested by using a pipette gun or an automatic liquid dispensing device; wherein, an equal amount of electrolyte with the same formula is injected into each of the preset containers, so that different samples react under the same electrolyte, thereby ensuring the consistency of experimental conditions and the comparability of test results; the injection amount of the electrolyte can be set according to the size of the electrode sheet, the load amount and the subsequent test requirements, thereby forming an effective electrode-electrolyte contact interface to simulate the chemical reaction conditions in the actual battery cell environment.

[0103] Furthermore, step S22B also includes: injecting electrolyte into a preset container storing the fresh positive electrode sheet to be tested, injecting electrolyte into a preset container storing the fresh negative electrode sheet to be tested, and injecting electrolyte into a preset container storing the electrolyte to be tested; wherein, an equal amount of electrolyte with the same formula is injected into each of the preset containers.

[0104] Step S23B: sealing the preset container into which the electrolyte is injected.

[0105] It should be noted that, in this embodiment, the specific implementation of step S22B and step S23B remains completely consistent with the corresponding step S22A and step S23A in the above embodiment. Those skilled in the art may implement this step with reference to the detailed description of the above embodiment. To avoid repetition, they will not be described here.

[0106] Step S24B: After the preset container is packaged, the preset container is placed in a constant temperature box for storage, wherein the constant temperature box has the preset temperature.

[0107] Specifically, in step S24B, the preset temperature of the constant temperature box is greater than or equal to 75°C and less than or equal to 85°C, and the storage time at the preset temperature is greater than or equal to 12 hours and less than or equal to 168 hours; wherein, the preset temperature and storage time can be set according to the battery cell application scenario or accelerated test requirements, for example, the preset container is stored in a constant temperature box at 85±1°C for 24 hours to accelerate the reaction process between the electrode material and the electrolyte under controllable conditions, thereby more significantly characterizing the gas production behavior of different electrode sheets after being treated with different formation processes.

[0108] Step S30: collecting the gases generated by the positive electrode sheet to be tested and the negative electrode sheet to be tested in the corresponding preset containers.

[0109] Specifically, in step S30, the gas in each of the preset containers after the constant temperature storage treatment is collected and quantitatively analyzed to obtain gas information generated by the reaction between the electrode material and the electrolyte after being processed by different chemical processes.

[0110] Furthermore, the step S30 further includes: collecting gases generated by the fresh positive electrode sheet to be tested, the fresh negative electrode sheet to be tested, and the electrolyte to be tested in the corresponding preset containers.

[0111] Step S40: performing gas analysis on the gas generated by the positive electrode sheet to be tested and the negative electrode sheet to be tested respectively.

[0112] Specifically, in step S40, the gas production corresponding to the collected positive electrode sheet and the negative electrode sheet to be tested is analyzed. During the analysis process, the electrode sheet after gas production is connected to a gas bag for gas collection, and gas chromatography (GC) and other analytical methods are used to identify and quantitatively analyze the components of the collected gas samples, thereby obtaining the types and relative contents of various gases (such as CO2, H2, CH4, C2H4, C2H6, etc.).

[0113] It is understandable that by comparing the gas composition and gas production of electrode sheets treated with different chemical processes, the reaction behavior between the electrode material and the electrolyte and its potential risks can be revealed, providing a reference basis for battery cell design and process optimization.

[0114] It should be noted that in step S40, gas analysis can also be performed on the gases generated by the positive electrode sheet to be tested, the negative electrode sheet to be tested, the fresh positive electrode sheet to be tested, the fresh negative electrode sheet to be tested, and the electrolyte to be tested, so as to further provide a reference basis for battery cell design and process optimization.

[0115] Step S50: collecting images of the positive electrode sheet to be tested and the negative electrode sheet to be tested.

[0116] Step S60: performing image recognition on the image to obtain characteristic information of the positive electrode sheet to be tested and the negative electrode sheet to be tested, wherein the characteristic information includes at least one of the surface morphology characteristics, particle crack characteristics, porosity change characteristics, or deposition characteristics of electrolyte decomposition products of the positive electrode sheet to be tested and the negative electrode sheet to be tested.

[0117] It should be noted that, in this embodiment, the specific implementation of step S50 and step S60 remains completely consistent with the corresponding steps S50 and step S60 in the above embodiment. Those skilled in the art may refer to the detailed description of the above embodiment to implement this step. To avoid repetition, they will not be described here.

[0118] The technical solutions of the embodiments of the present application are now described in conjunction with specific embodiments.

[0119] Example 1

[0120] A method for testing gas generation of a battery cell, comprising:

[0121] S1: Obtain multiple battery cells to be tested, and adjust different battery cells to 50% SOC and 100% SOC respectively through charge and discharge; wherein the multiple battery cells to be tested are battery cells of the same model and are all pre-treated using the same formation process.

[0122] The battery cell to be tested is a soft-pack square battery cell (GR / / LCO system), and the rated capacity of the battery cell to be tested is 1900 mAh.

[0123] The charging and discharging process includes: charging the multiple cells to be tested at a constant current of 0.5C until the voltage reaches 4.4V, switching to a constant voltage of 4.4V, and terminating when the charging current drops to 0.05C, thereby adjusting the SOC of the cells to be tested to 100%; discharging the cells that have been charged to 100% SOC at a constant current of 0.5C until the discharge capacity reaches 950mAh, thereby adjusting the SOC of the cells to be tested to 50%.

[0124] The formation process includes: first, placing the battery cell to be tested in a formation fixture, applying a constant pressure of 1.2 MPa to the battery cell to be tested through the formation fixture, and allowing the battery cell to be tested to stand for 1 minute in an environment of 80°C; then, charging with a constant current of 0.05C for 3 minutes, 0.1C for 2 minutes, 1C for 60 minutes, and 0.3C for 10 minutes in sequence; finally, allowing the battery cell to be tested to stand for 20 minutes again to promote system stability and complete the formation process.

[0125] S2: Disassemble the multiple battery cells to be tested, separate the positive and negative electrode sheets in the battery cells to be tested, and use a hole extractor to take out multiple positive electrode sheets to be tested with 50% SOC, multiple positive electrode sheets to be tested with 100% SOC, multiple negative electrode sheets to be tested with 50% SOC, and multiple negative electrode sheets to be tested with 100% SOC of the same size from the positive and negative electrode sheets.

[0126] The electrode sheets (the positive electrode sheet and the negative electrode sheet) are circular electrode sheets with a diameter of 15 mm.

[0127] S3: In a vacuum environment with a dew point less than -40°C, a plurality of the positive electrode sheets to be tested and a plurality of the negative electrode sheets to be tested with different charge states are placed in aluminum-plastic film bags respectively; wherein the thickness of the aluminum-plastic film bag is 115 microns.

[0128] S4: injecting electrolyte into the aluminum-plastic film bags; wherein, an equal amount of electrolyte with the same formula is injected into each aluminum-plastic film bag.

[0129] The electrolyte includes but is not limited to lithium hexafluorophosphate (LiPF6) with a concentration of 1 mol / L dissolved in a solvent system consisting of ethyl carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC) and fluoroethylene carbonate (FEC), and propane sultone (PS ) additive.

[0130] S5: placing the aluminum-plastic film bag in a constant temperature box for storage, wherein the preset temperature of the constant temperature box is 80° C. and the storage time in the constant temperature box is 24 hours.

[0131] S6: Collect the gases generated by the positive electrode sheets to be tested and the negative electrode sheets to be tested in the corresponding preset containers, respectively, wherein the gases generated by the multiple positive electrode sheets to be tested with 100% SOC are defined as the first experimental group, the gases generated by the multiple negative electrode sheets to be tested with 100% SOC are defined as the second experimental group, the gases generated by the multiple positive electrode sheets to be tested with 50% SOC are defined as the third experimental group, and the gases generated by the multiple negative electrode sheets to be tested with 50% SOC are defined as the fourth experimental group.

[0132] S7: Analyze the gas production corresponding to the collected positive electrode sheet to be tested and the negative electrode sheet to be tested by gas chromatography to obtain the types of various gases and their relative contents.

[0133] Table 1

[0134]

[0135] It should be noted that the "Y" in Table 1 indicates the gas conditions generated when multiple positive electrode sheets to be tested and multiple negative electrode sheets to be tested are tested in their respective preset containers for different experimental groups in Example 1; specifically, the "Y" mark in Table 1 indicates the gas release phenomenon of the positive electrode sheets to be tested and the negative electrode sheets to be tested in their respective containers in the corresponding experimental groups, indicating the generation and accumulation of gas under different experimental conditions.

[0136] It can be understood that, in combination with Example 1, Figure 2 As can be seen from Table 1, the multiple cells to be tested are of the same model, and the multiple cells to be tested are pretreated using the same formation process. The different cells to be tested are respectively regulated to at least two target states of charge through charge and discharge, thereby achieving a systematic study and comparative analysis of the electrode gas generation characteristics under different target states of charge, providing experimental basis and data support for subsequent cell design optimization, electrochemical behavior mechanism analysis and safety assessment.

[0137] Example 2

[0138] A method for testing gas generation of a battery cell, comprising:

[0139] S1: Processing a plurality of unformed cells according to a first formation process or a second formation process to obtain a plurality of cells to be tested; wherein each of the unformed cells is subjected to only one formation process, and the plurality of cells to be tested are cells of the same model.

[0140] The battery cell to be tested is a soft-pack square battery cell (GR / / LCO system), and the rated capacity of the battery cell to be tested is 1900 mAh.

[0141] The first formation process includes: first, placing the battery cell to be tested in a formation fixture, applying a constant pressure of 1.2 MPa to the battery cell to be tested through the formation fixture, and allowing the battery cell to be tested to stand for 1 minute in an 80°C environment; then, charging with a constant current of 0.05C for 3 minutes, 0.1C for 2 minutes, 1C for 60 minutes, and 0.3C for 10 minutes in sequence; finally, allowing the battery cell to be tested to stand for 20 minutes again to promote system stability and complete the formation process.

[0142] The second formation process includes: first, placing the battery cell to be tested in a formation fixture, applying a constant pressure of 1.2 MPa to the battery cell to be tested through the formation fixture, and allowing the battery cell to be tested to stand for 1 minute at 75°C; then, charging with a constant current of 0.05C for 3 minutes, 0.1C for 2 minutes, 1C for 48 minutes, and 0.3C for 10 minutes in sequence; finally, allowing the battery cell to be tested to stand for 20 minutes again to promote system stability and complete the formation process.

[0143] S2: regulating the SOC of the different cells to be tested to 100% by charging.

[0144] The charging process includes: charging at a constant current of 0.5C until the voltage reaches 4.4V, then switching to a constant voltage of 4.4V, and terminating when the charging current drops to 0.05C, completing the charging to 100% SOC.

[0145] S3: disassembling the plurality of cells to be tested, separating the positive electrode sheets and the negative electrode sheets in the cells to be tested, and using a hole extractor to take out a plurality of positive electrode sheets to be tested and a plurality of negative electrode sheets to be tested of the same size from the positive electrode sheets and the negative electrode sheets.

[0146] The electrode sheets (the positive electrode sheet and the negative electrode sheet) are circular electrode sheets with a diameter of 15 mm.

[0147] S3: In a vacuum environment with a dew point less than -40°C, a plurality of the positive electrode sheets to be tested and a plurality of the negative electrode sheets to be tested with different charge states are placed in aluminum-plastic film bags respectively; wherein the thickness of the aluminum-plastic film bag is 115 microns.

[0148] S4: injecting electrolyte into the aluminum-plastic film bags; wherein, an equal amount of electrolyte with the same formula is injected into each aluminum-plastic film bag.

[0149] The electrolyte includes but is not limited to lithium hexafluorophosphate (LiPF6) with a concentration of 1 mol / L dissolved in a solvent system consisting of ethyl carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC) and fluoroethylene carbonate (FEC), and propane sultone (PS ) additive.

[0150] S5: placing the aluminum-plastic film bag in a constant temperature box for storage, wherein the preset temperature of the constant temperature box is 80° C. and the storage time in the constant temperature box is 24 hours.

[0151] S6: Collect the gases generated by the positive electrode sheets to be tested and the negative electrode sheets to be tested in the corresponding preset containers, respectively, wherein the gases generated by the multiple positive electrode sheets to be tested treated by the first formation process are defined as the fifth experimental group, the gases generated by the multiple negative electrode sheets to be tested treated by the first formation process are defined as the sixth experimental group, the gases generated by the multiple positive electrode sheets to be tested treated by the second formation process are defined as the seventh experimental group, and the gases generated by the multiple positive electrode sheets to be tested treated by the second formation process are defined as the eighth experimental group.

[0152] S7: Analyze the gas production corresponding to the collected positive electrode sheet to be tested and the negative electrode sheet to be tested by gas chromatography to obtain the types of various gases and their relative contents.

[0153] Table 2

[0154]

[0155] It should be noted that the "Y" in Table 2 indicates the gas conditions generated when multiple positive electrode sheets to be tested and multiple negative electrode sheets to be tested were tested in their respective preset containers for different experimental groups in Example 2; specifically, the "Y" mark in Table 2 indicates the gas release phenomenon of the positive electrode sheets to be tested and the negative electrode sheets to be tested in their respective containers in the corresponding experimental groups, indicating the generation and accumulation of gas under different experimental conditions.

[0156] It can be understood that, in combination with Example 2, Figure 3 As can be seen from Table 2, the multiple cells to be tested are of the same model and have the same state of charge. By processing the multiple cells to be tested according to two different formation processes, a comparative analysis of the gas generation characteristics of the electrode under different formation processes and their impact on the cell performance is achieved, providing experimental basis and data support for subsequent cell design optimization, electrochemical behavior mechanism analysis and safety assessment.

[0157] See also Figure 4 This embodiment provides a battery cell gas production testing system 1, which is used to evaluate the gas production behavior and analyze the gas components of battery cell electrodes that have undergone different formation processes or under different charge state conditions.

[0158] The battery cell gas production testing system 1 can execute some or all of the steps described in the battery cell gas production testing method provided in the above-mentioned embodiment of the present application, so as to analyze the gas information of the electrode gas production under different formation processes or charging conditions; wherein, the gas information includes gas composition information and / or gas content information.

[0159] Specifically, the battery cell gas generation testing system 1 includes a preset container 11 , a temperature control device 12 , a collection device 13 and an analysis device 14 .

[0160] The preset container 11 is used to seal and package the positive electrode sheet to be tested and the negative electrode sheet to be tested, respectively, and is injected with electrolyte; the temperature control device 12 is used to place the preset container 11 and keep the preset container 11 in a preset temperature environment; the collecting device 13 is used to collect the gases generated by the positive electrode sheet to be tested and the negative electrode sheet to be tested in the corresponding preset containers 11; the analyzing device 14 is used to perform gas analysis on the gases generated by the positive electrode sheet to be tested and the negative electrode sheet to be tested, respectively, to obtain the gas production measurement results of the battery cells corresponding to the positive electrode sheet to be tested and the negative electrode sheet to be tested.

[0161] It can be understood that the preset container 11, the temperature control device 12, the collection device 13 and the analysis device 14 can be used to respectively execute steps S10 to S40 in the aforementioned method embodiment. For more details, please refer to the introduction of the above method steps, which will not be repeated here.

[0162] Furthermore, the battery cell gas production test system 1 also includes an image acquisition device and an image recognition and analysis device, which are used to obtain and analyze the microstructure images of the electrode before and after storage, and evaluate the relationship between gas production and electrode structure changes from the dimensions of surface morphology, particle changes, crack generation and product deposition.

[0163] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0164] The above is a detailed introduction to a test method and test system for gas production of a battery cell provided in this embodiment. Specific examples are used in this article to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method of this application and its core idea; at the same time, for technical personnel in this field, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on this application.

Claims

1. A method for testing gas production of a battery cell, characterized in that: include: Provide the positive electrode sheet and the negative electrode sheet to be tested; The positive electrode sheet to be tested and the negative electrode sheet to be tested are respectively sealed and packaged in a preset container filled with electrolyte, and the preset containers are stored in a preset temperature environment; Collecting the gases generated by the positive electrode sheet to be tested and the negative electrode sheet to be tested in the corresponding preset containers respectively; Gas analysis is performed on the gases generated by the positive electrode sheet to be tested and the negative electrode sheet to be tested respectively.

2. The method for testing gas generation of a battery cell according to claim 1, wherein: Providing the positive electrode sheet to be tested and the negative electrode sheet to be tested includes: Acquire multiple battery cells to be tested, and regulate different battery cells to be tested to at least two target states of charge by charging and discharging; The plurality of cells to be tested are disassembled, and the positive electrode sheets and the negative electrode sheets in the cells to be tested are separated respectively, so as to obtain the plurality of positive electrode sheets to be tested and the plurality of negative electrode sheets to be tested with different states of charge.

3. The method for testing gas generation of a battery cell according to claim 1, wherein: Providing the positive electrode sheet to be tested and the negative electrode sheet to be tested includes: Processing a plurality of unformed battery cells according to at least two different formation processes to obtain a plurality of battery cells to be tested; The plurality of cells to be tested are disassembled and the positive and negative electrode sheets in the plurality of cells to be tested are separated to obtain a plurality of positive electrode sheets to be tested and a plurality of negative electrode sheets to be tested having different formation processes.

4. The method for testing gas generation of a battery cell according to claim 1, wherein: The step of sealing the positive electrode sheet to be tested and the negative electrode sheet to be tested in preset containers filled with electrolyte comprises: Placing the positive electrode sheet to be tested and the negative electrode sheet to be tested into the preset containers respectively; injecting electrolyte into the preset container; The preset container filled with the electrolyte is sealed.

5. The method for testing gas generation of a battery cell according to claim 4, wherein: The sealing of the preset container into which the electrolyte is injected comprises: The air in the preset container is exhausted, and the opening of the preset container is heat-sealed; wherein the heat-sealing temperature is greater than or equal to 150° C. and less than or equal to 180° C.; and the heat-sealing time is greater than or equal to a preset time.

6. The method for testing gas generation of a battery cell according to claim 4, wherein: The preset temperature is greater than or equal to 75°C and less than or equal to 85°C; And / or, the storage time at the preset temperature is greater than or equal to 12 hours and less than or equal to 168 hours.

7. The method for testing gas generation of a battery cell according to claim 4, wherein: The preset container is an aluminum-plastic film bag, and the thickness of the preset container is greater than or equal to 96 microns and less than or equal to 115 microns.

8. The method for testing gas generation of a battery cell according to claim 1, wherein: The battery cell gas production test method further includes: Capturing images of the positive electrode sheet to be tested and the negative electrode sheet to be tested; Image recognition is performed on the picture to obtain characteristic information of the positive electrode sheet to be tested and the negative electrode sheet to be tested, wherein the characteristic information includes at least one of the surface morphology characteristics, particle crack characteristics, porosity change characteristics, or deposition characteristics of electrolyte decomposition products of the positive electrode sheet to be tested and the negative electrode sheet to be tested.

9. The method for testing gas generation of a battery cell according to claim 8, wherein: The battery cell gas production test method further includes: According to the characteristic information and / or the gas production measurement result, the performance impact information of the positive electrode sheet to be tested and the negative electrode sheet to be tested under at least two target charge states or at least two different formation processes is analyzed and determined.

10. A battery cell gas production testing system, characterized in that: include The pre-set container is used to seal and package the positive electrode sheet to be tested and the negative electrode sheet to be tested respectively, and is filled with electrolyte; A temperature control device, used to place the preset container and keep the preset container in a preset temperature environment; A collecting device, used to collect the gas generated by the positive electrode sheet to be tested and the negative electrode sheet to be tested in the corresponding preset containers; The analyzing device is used to perform gas analysis on the gas generated by the positive electrode sheet to be tested and the negative electrode sheet to be tested respectively, and obtain the gas production measurement results of the battery cells corresponding to the positive electrode sheet to be tested and the negative electrode sheet to be tested.

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