Method and equipment for testing infiltration degree of battery electrolyte

Abstract

The invention relates to the related technical field of battery detection, and discloses a method and equipment for testing the infiltration degree of a battery electrolyte, the method for testing the infiltration degree of the battery electrolyte comprises the following steps: providing a battery monomer infiltrated by the electrolyte, the battery monomer comprises the electrolyte and an electrode assembly infiltrated in the electrolyte, the electrode assembly comprises a positive plate, a separator and a negative plate which are arranged in sequence; charging the battery cells infiltrated by the electrolyte by using a current with a preset charging rate, and charging the battery cells to a preset capacity; in a preset environment, obtaining a disassembled negative plate of the charged single battery; disassembling the negative plate, and volatilizing the electrolyte on the surface in a preset environment; and judging the infiltration degree of the electrolyte according to the surface gray scale information of the disassembled negative plate after the electrolyte is volatilized. The detection accuracy of the electrolyte infiltration degree is improved.

Description

Technical Field

[0001] The present application relates to the technical field related to battery detection, and in particular to a method and device for testing the degree of battery electrolyte infiltration. Background Art

[0002] This section merely provides background information related to the present application and is not necessarily prior art.

[0003] Battery devices are capable of storing electrical energy and can be widely used in electronic devices such as mobile phones, laptop computers, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and electric tools.

[0004] How to improve the energy storage capacity and cycle performance of battery devices has always been the focus of attention in the process of battery device research and development. In the process of battery device research and development and production, it is usually necessary to test the electrolyte infiltration degree of the battery device to determine whether the energy storage capacity and cycle performance of the battery device meet product expectations. How to accurately determine the electrolyte infiltration degree of the battery device has always been a continuous concern in the process of battery device research and development. Summary of the invention

[0005] In view of the above problems, the present application provides a method and equipment for testing the degree of battery electrolyte infiltration to improve the accuracy of the degree of battery electrolyte infiltration, so as to adjust the relevant parameters of battery production and improve the energy storage capacity and cycle performance of the battery device.

[0006] The first aspect of the present application proposes a method for testing the degree of electrolyte infiltration of a battery, comprising: providing a battery cell that has been infiltrated with an electrolyte, the battery cell comprising an electrolyte and an electrode assembly infiltrated in the electrolyte, the electrode assembly comprising a positive electrode sheet, a separator and a negative electrode sheet arranged in sequence; charging the battery cell that has been infiltrated with the electrolyte using a current of a preset charging rate and charging it to a preset capacity, the current of the preset charging rate being greater than a calibrated charging current of the battery cell; obtaining a disassembled negative electrode sheet of the charged battery cell under a preset environment; causing the disassembled negative electrode sheet to volatilize the surface electrolyte under the preset environment; and judging the degree of electrolyte infiltration based on the surface grayscale information of the disassembled negative electrode sheet after the electrolyte volatilization is completed.

[0007] In the technical solution of the embodiment of the present application, the battery cell is charged by using a large current greater than the calibrated charging current, so that the active ions in the electrolyte are quickly embedded in the negative electrode sheet, and the negative electrode sheet of the electrode assembly is quickly charged to a preset capacity. After the surface electrolyte evaporates, there will be a color difference (i.e., grayscale difference) between the position where the active ions are embedded on the surface and the position where the active ions are not embedded. The degree of wetting of the electrode sheet by the electrolyte can be intuitively obtained through the color difference (i.e., grayscale difference) on the surface of the negative electrode sheet. The operation is simple and the degree of wetting of the electrolyte can be more accurately reflected, thereby improving the detection accuracy. According to the more accurate detection results, the accuracy of selecting or adjusting relevant parameters for battery production can be improved, so that the electrolyte dispersion of the processed battery cell is more uniform, thereby improving the energy storage capacity, cycle performance and reliability of the battery cell or the battery device including the battery cell.

[0008] In addition, the battery electrolyte infiltration degree test method according to the present application may also have the following additional technical features:

[0009] In some embodiments of the present application, the preset charging rate is greater than or equal to 0.6 times the charging rate of the battery cell, and / or the preset capacity is set to 0.65 times the rated capacity of the battery cell. The limitation of the preset charging rate can increase the embedding speed of active ions (such as lithium ions) and shorten the time for the battery cell to be charged to the preset capacity, thereby reducing the impact of the charging process on the electrolyte infiltration degree and improving the detection accuracy of the electrolyte infiltration degree. The limitation of the preset capacity can make the disassembled negative electrode sheet of the battery cell charged to the preset capacity have a more obvious grayscale difference (the grayscale difference between the grayscale of the negative electrode sheet after the active ions are embedded and the grayscale of the negative electrode sheet without the active ions embedded), improve the detection accuracy of the electrolyte infiltration degree, and do not need to charge the battery cell to an excessively high capacity, saving electric energy, thereby reducing the testing cost.

[0010] In some embodiments of the present application, the method for testing the degree of electrolyte infiltration of the battery also includes: determining the preset capacity of the battery cell, including: using the current of the preset charging rate to charge the multiple battery cells that have been infiltrated with the electrolyte, and the multiple battery cells are respectively charged to different capacities; under the preset environment, obtaining the separated negative electrode sheets of the multiple battery cells that have been charged; allowing the obtained separated negative electrode sheets to volatilize the electrolyte under the preset environment; based on the surface grayscale information of each of the separated negative electrode sheets that have completed electrolyte volatilization, selecting the capacity of the battery cell corresponding to the separated negative electrode sheet with the largest grayscale difference as the preset capacity, the grayscale difference being the difference between the grayscale corresponding to the negative electrode sheet without active ions embedded therein and the grayscale corresponding to the negative electrode sheet with active ions embedded therein. When testing the electrolyte wettability of a battery cell, first determine the preset capacity of the current battery cell. In this way, during the electrolyte wettability test, the separated negative electrode sheet obtained can have a more obvious grayscale difference (the grayscale difference is the difference between the grayscale of the negative electrode sheet after the active ions are embedded and the grayscale of the negative electrode sheet without the active ions embedded), thereby improving the accuracy of the detection of the electrolyte wettability.

[0011] In some embodiments of the present application, the capacity of the battery cell corresponding to the separated negative electrode sheet with the largest grayscale difference is selected as the preset capacity, including: selecting the separated negative electrode sheet with the largest grayscale difference; from the separated negative electrode sheets with the largest grayscale difference, selecting the separated negative electrode sheet with the largest difference between the grayscale at the center and the grayscale on both sides in the width direction, and taking the capacity of the battery cell corresponding to the selected separated negative electrode sheet as the preset capacity, and the width direction is parallel to the wetting direction of the electrolyte into the separated negative electrode sheet during the process of the electrolyte infiltrating the electrode assembly.

[0012] In some embodiments of the present application, before providing the battery cell that has been soaked with the electrolyte, it also includes: a step of soaking the battery cell, including: providing a battery assembly with a shell and an electrode assembly assembled; injecting electrolyte into the shell of the battery assembly to form a preformed battery cell; allowing the preformed battery cell to stand for a preset period of time, and while the preformed battery cell is standing, detecting the infiltration path and degree of completion of the electrolyte on the electrode assembly. During the standing process of the preformed battery cell, the infiltration path of the electrolyte on the electrode assembly is detected, so that it can be known whether the electrolyte has been soaked along the expected path, which can be used as a reference for subsequent parameter adjustment and judgment of the performance of the battery cell. During the standing process of the preformed battery cell, the degree of completion of the electrolyte on the electrode assembly is detected, so that the approximate degree of electrolyte soaking of the electrode assembly after the standing is completed can be known.

[0013] In some embodiments of the present application, the detection of the electrolyte's wetting path and wetting completion of the electrode assembly includes: irradiating the preformed battery cell with X-rays, acquiring an image of the preformed battery cell, and analyzing the electrolyte's wetting path and wetting completion of the electrode assembly based on the image. By visually observing the lithium ion combination with the X-ray method, the electrolyte's wetting degree and path can be quantitatively characterized.

[0014] In some embodiments of the present application, the humidity of the preset environment is 0.2% to 0.4%, and the temperature of the preset environment is 10° C. to 25° C. The limitation of the preset environment can reduce the influence of environmental factors on the grayscale of the disassembled negative electrode sheet, improve the detection accuracy of the electrolyte infiltration degree, and increase the volatilization speed of the electrolyte, thereby shortening the detection time of the electrolyte infiltration degree.

[0015] In some embodiments of the present application, judging the electrolyte infiltration degree according to the surface grayscale information of the disassembled negative electrode sheet after the electrolyte volatilization is completed includes: judging the electrolyte infiltration degree according to the area of ​​the grayscale region of the disassembled negative electrode sheet where no active ions are embedded, or judging the electrolyte infiltration degree according to the area of ​​the grayscale region of the disassembled negative electrode sheet where active ions are embedded. Using the area as a reference value for judgment is more intuitive, and improves the detection efficiency and accuracy of the electrolyte infiltration degree.

[0016] In some embodiments of the present application, judging the electrolyte infiltration degree according to the surface grayscale information of the disassembled negative electrode sheet after the electrolyte volatilization is completed includes: confirming that the electrolyte has not been fully infiltrated according to the grayscale area without active ions embedded in the center of the disassembled negative electrode sheet along its own width direction, and the unit area of ​​the grayscale area without active ions embedded in it is greater than or equal to the preset unit area, and the self-width direction of the disassembled negative electrode sheet is parallel to the infiltration direction of the electrolyte to the disassembled negative electrode sheet during the process of the electrolyte infiltrating the electrode assembly; according to the center of the disassembled negative electrode sheet along its own width direction, there is no grayscale area without active ions embedded in the negative electrode sheet, or the center of the disassembled negative electrode sheet along its own width direction has a grayscale area without active ions embedded in the negative electrode sheet, and the unit area of ​​the grayscale area without active ions embedded in it is less than the preset unit area, confirming that the electrolyte infiltration is completed. By disassembling the grayscale area at the center of the negative electrode sheet along its own width direction, it can be more accurately determined whether the electrolyte has been fully infiltrated.

[0017] The second aspect of the present application proposes a test device for the degree of electrolyte infiltration of a battery, comprising a preparation device, a charging device, a disassembly device, a volatilization device and an analysis device, wherein the preparation device is used to provide a battery cell that has been infiltrated with an electrolyte, wherein the battery cell comprises an electrolyte and an electrode assembly infiltrated in the electrolyte, wherein the electrode assembly comprises a positive electrode sheet, a separator and a negative electrode sheet arranged in sequence; the charging device is used to charge the battery cell that has been infiltrated with an electrolyte using a current of a preset charging rate and to charge it to a preset capacity; the disassembly device is used to obtain a disassembled negative electrode sheet of the charged battery cell under a preset environment; the volatilization device is used to support the disassembled negative electrode sheet and volatilize the surface electrolyte of the disassembled negative electrode sheet under the preset environment; the analysis device is used to obtain the surface grayscale information of the disassembled negative electrode sheet after the electrolyte volatilization is completed, and judge the degree of electrolyte infiltration according to the surface grayscale information of the disassembled negative electrode sheet after the electrolyte volatilization is completed.

[0018] The battery electrolyte infiltration degree testing device of the present application and the battery electrolyte infiltration degree testing method proposed in the present application have the same beneficial effects, which will not be described in detail here.

[0019] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Also, the same reference numerals are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0021] Figure 1 A schematic structural diagram of a battery device proposed in some embodiments of the present application;

[0022] Figure 2 A schematic structural diagram of a battery cell proposed in some embodiments of the present application;

[0023] Figure 3 A schematic cross-sectional diagram of an electrode assembly according to some embodiments of the present application;

[0024] Figure 4 Schematic cross-sectional views of electrode assemblies of other embodiments of the present application;

[0025] Figure 5 A flow chart of a method for testing the degree of electrolyte wetting in a battery according to some embodiments of the present application;

[0026] Figure 6 A flow chart for determining a preset capacity of a battery cell proposed in some embodiments of the present application;

[0027] Figure 7 A flow chart for selecting the capacity of a battery cell corresponding to a separated negative electrode sheet with the largest grayscale difference as a preset capacity, proposed in some embodiments of the present application;

[0028] Figure 8 A flow chart of soaking a battery cell according to some embodiments of the present application;

[0029] Fig. 9 What is shown is a table showing the relationship between the capacity of a battery cell and the surface grayscale information of a disassembled negative electrode sheet;

[0030] Fig.10 Shown is a table showing the relationship between the duration of the electrode assembly being soaked and the degree of electrolyte soaking;

[0031] Fig.11 Shown is a table showing the relationship between the cold pressing time of the electrode assembly and the electrolyte infiltration degree;

[0032] Fig.12 Shown is a table showing the relationship between the cold pressing pressure of the electrode assembly and the electrolyte infiltration degree;

[0033] Fig.13 A schematic diagram of a testing device for the battery electrolyte wetting degree proposed in some embodiments of the present application.

[0034] The reference numerals in the specific implementation manner are as follows:

[0035] 100, battery device; 10, housing; 20, battery cell assembly; 21, battery cell; 22, housing; 23, housing; 24, end cap; 25, electrode assembly; 251, positive electrode sheet; 252, negative electrode sheet; 253, separator; 26, tab; 27, electrode terminal;

[0036] 610, preparation device; 620, charging device; 630, disassembly device; 640, volatilization device; 650, analysis device. DETAILED DESCRIPTION

[0037] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0039] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0040] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0041] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0042] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0043] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0044] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0045] A battery device may include one or more battery cells. A battery cell generally includes an electrolyte and an electrode assembly immersed in the electrolyte. The degree of wetting between the electrolyte and the electrode assembly has a great influence on the energy storage capacity and cycle performance of the battery cell. Insufficient electrolyte wetting will lead to poor uniformity of electrolyte dispersion. Electrolyte aggregation in local areas can easily cause lithium precipitation, which in turn causes a short circuit in the battery cell, affecting the reliability of the battery cell.

[0046] Parameters such as the cold pressing pressure and cold pressing time of the electrode assembly are one of the key factors affecting the wetting effect of the electrolyte infiltration. During the injection and standing process of the battery cell, the electrolyte will penetrate from the edge of the pole piece through the isolation membrane to the pole piece pores and the center of the battery cell. As the thickness and area of ​​the pole piece increase, the electrolyte infiltration distance becomes longer and the infiltration speed slows down. The optimal parameters for battery cell injection, standing and formation require a lot of experimental verification. Therefore, when conducting experiments to optimize the cold pressing parameters, standing and formation parameters and conditions of the battery cell, an accurate and fast method is needed to understand the distribution of the electrolyte in the electrode assembly in order to maximize the energy storage capacity, cycle performance and reliability of the battery cell.

[0047] In the production and testing process of battery cells, the electrolyte infiltration is usually judged by the blue light penetrating the isolation film and the scattering of the phosphor. This test method cannot intuitively judge the degree and path of electrolyte infiltration into the electrode, and has low accuracy. Thus, relying on this test method, the optimization and adjustment of the cold pressing parameters, static and formation parameters and conditions of the battery cell are low in accuracy, which makes the research and development of the battery cell difficult and is not conducive to obtaining the best production parameters and conditions, thus affecting the energy storage capacity, cycle performance and reliability of the battery cell.

[0048] Based on this, in order to improve the problem of low accuracy in electrolyte infiltration detection, it was found through research that after the negative electrode sheet is charged to a certain capacity, the surface color of the negative electrode sheet after the active ions are embedded is different from the surface color of the negative electrode sheet without the active ions embedded. Based on this research, the present application provides a method for testing the degree of electrolyte infiltration in a battery, by charging the battery cell with a large current exceeding the calibrated charging current, so that the active ions in the electrolyte are quickly embedded in the negative electrode sheet, and charged to a preset capacity, and then by disassembling the battery cell, observing the interface color difference (i.e., grayscale difference) of the disassembled negative electrode sheet, intuitively observing the degree of infiltration and path of the battery cell, judging the influence of the cold pressing time, cold pressing pressure and other parameters of the electrode assembly on the electrolyte infiltration, improving the accuracy of the detection of the electrolyte infiltration degree, shortening the detection time, and being conducive to obtaining the best production parameters and conditions of the battery cell, thereby improving the energy storage capacity, cycle performance and reliability of the battery cell.

[0049] The test method for the degree of electrolyte wetting of a battery disclosed in the embodiment of the present application can be applied to the detection of electrolyte wetting of secondary batteries such as lithium-ion batteries and sodium-ion batteries. The battery cell or battery device involved in this embodiment can be applied to electrical equipment, which can be but not limited to mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, etc. Among them, electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecrafts, etc.

[0050] like Figure 1 As shown, Figure 1 This is a schematic diagram of the structure of a battery device proposed in some embodiments of the present application. The battery device 100 mentioned in the embodiments of the present application may include one or more battery cell assemblies 20 for providing voltage and capacity. The battery cell assembly 20 may include one or more battery cells 21, wherein the multiple battery cells 21 are connected in series, in parallel, or in mixed connection through a busbar component.

[0051] The battery device 100 may further include a housing 10 , in which the battery cell assembly 20 is disposed.

[0052] like Figure 2 As shown, Figure 2 This is a simplified schematic diagram of the structure of a battery cell proposed in some embodiments of the present application. In the embodiments of the present application, the battery cell 21 may be a secondary battery. A secondary battery refers to a battery cell 21 that can be continuously used by activating the active material by charging after the battery cell 21 is discharged.

[0053] The battery cell 21 can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel hydrogen battery, a nickel cadmium battery, a lead storage battery, etc., which is not limited in the embodiments of the present application.

[0054] The battery cell 21 generally includes a housing 22, an electrode assembly 25 and an electrode terminal 27. The electrode terminal 27 is disposed on the housing 22, the electrode assembly 25 is disposed in the housing 22, and the electrode terminal 27 is electrically connected to the tab 26 of the electrode assembly 25. Figure 3 and Figure 4 As shown, Figure 3 is a schematic cross-sectional diagram of an electrode assembly according to some embodiments of the present application. Figure 4 The cross-sectional schematic diagram of the electrode assembly of some other embodiments of the present application, the electrode assembly 25 includes a positive electrode sheet 251, a negative electrode sheet 252 and a separator, and the separator is arranged between the negative electrode sheet 252 and the positive electrode sheet 251. During the charging and discharging process of the battery cell 21, active ions (such as lithium ions) are embedded and removed back and forth between the positive electrode sheet 251 and the negative electrode sheet 252. The separator is arranged between the positive electrode sheet 251 and the negative electrode sheet 252, which can prevent the positive and negative electrodes from short-circuiting, and at the same time allow the active ions to pass through.

[0055] The positive electrode sheet 251 may include a positive electrode collector and a positive electrode active material disposed on at least one surface of the positive electrode collector.

[0056] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is disposed on either or both of the two facing surfaces of the positive electrode current collector.

[0057] As an example, the positive electrode current collector may be a metal foil, a conductive polymer material, a carbon material or a composite current collector. For example, as a metal foil, a pure metal, an alloy, a surface-treated metal, including but not limited to stainless steel, copper, aluminum, nickel, titanium or silver, etc., may be used. The composite current collector may include a polymer material base and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0058] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries can also be used. These positive electrode active materials can be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4, referred to as LFP), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, also referred to as NCM333; LiNi 0.5 Co 0.2 Mn 0.3 O2, also referred to as NCM523; LiNi 0.5 Co 0.25 Mn 0.25 O2, also referred to as NCM211; LiNi 0.6 Co 0.2 Mn 0.2 O2, also referred to as NCM622; LiNi 0.8 Co 0.1 Mn 0.1 O2, also referred to as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi 0.8 Co 0.15 Al 0.05 O2) and at least one of its modified compounds. The modified compound refers to a substance obtained by modifying the above substances by means of doping or coating.

[0059] The negative electrode sheet 252 may include a negative electrode current collector.

[0060] As an example, the negative electrode current collector may be a metal foil, a conductive polymer material, a carbon material or a composite current collector. For example, as the metal foil, a pure metal, an alloy, a surface-treated metal, including but not limited to stainless steel, copper, aluminum, nickel, titanium or silver, etc., may be used. The composite current collector may include a polymer material base and a metal layer. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0061] As an example, the negative electrode sheet 252 may include a negative electrode collector and a negative electrode active material disposed on at least one surface of the negative electrode collector.

[0062] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is disposed on either or both of the two facing surfaces of the negative electrode current collector.

[0063] As an example, the negative electrode active material may adopt the negative electrode active material for the battery cell 21 known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for the battery cell 21 may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0064] In some embodiments, the isolation member is an isolation membrane 253. The present application has no particular limitation on the type of isolation membrane 253, and any known porous structure isolation membrane with good chemical stability and mechanical stability can be selected.

[0065] As an example, the main material of the isolation membrane 253 can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramics. The isolation membrane 253 can be a single-layer film or a multi-layer composite film, without special restrictions. When the isolation membrane 253 is a multi-layer composite film, the materials of each layer can be the same or different, without special restrictions. The isolation member can be a separate component located between the positive and negative electrodes, or it can be attached to the surface of the positive and negative electrodes. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can also be coated on the surface of the isolation membrane 253.

[0066] The battery cell 21 also includes an electrolyte, which contains electrolytes that conduct ions between the positive and negative electrodes. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs.

[0067] Illustratively, the electrolyte solution includes an electrolyte salt and a solvent, and the electrolyte salt serves as an electrolyte.

[0068] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0069] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone. The solvent can also be selected from ether solvents. Ether solvents can include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether.

[0070] The electrode assembly 25 may be a wound structure, a laminated structure, or a mixed structure of a wound structure and a laminated structure.

[0071] In some embodiments, Figure 3 As shown, the electrode assembly 25 is a winding structure. The positive electrode sheet 251 and the negative electrode sheet 252 are wound into a winding structure.

[0072] In some embodiments, Figure 4 As shown, the electrode assembly 25 is a laminate structure.

[0073] As an example, a plurality of positive electrode sheets 251 and a plurality of negative electrode sheets 252 may be provided respectively, and the plurality of positive electrode sheets 251 and the plurality of negative electrode sheets 252 may be alternately stacked.

[0074] As an example, a plurality of positive electrode sheets 251 may be provided, and the negative electrode sheet 252 may be folded to form a plurality of stacked folded segments, with one positive electrode sheet 251 being sandwiched between adjacent folded segments.

[0075] As an example, the positive electrode sheet 251 and the negative electrode sheet 252 are both folded to form a plurality of stacked folded sections.

[0076] As an example, a plurality of separators may be provided, each of which is provided between any adjacent positive electrode sheets 251 or negative electrode sheets 252 .

[0077] As an example, the separator may be disposed continuously, and disposed between any adjacent positive electrode sheets 251 or negative electrode sheets 252 by folding or winding.

[0078] In some embodiments, the shape of the electrode assembly 25 can be cylindrical, flat, or polygonal.

[0079] In some embodiments, the electrode assembly 25 is provided with tabs 26, which can conduct current from the electrode assembly 25. The tabs 26 include a positive tab 26 and a negative tab 26.

[0080] In some embodiments, the housing 22 may be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell), or an aluminum-plastic film.

[0081] In some embodiments, the housing 22 may be a sealed structure or a non-sealed structure. As an example, when the housing 22 is a non-sealed structure, the housing 22 plays a role in protecting the electrode assembly 25, and a sealed bag is also included between the housing 22 and the electrode assembly 25, and the sealed bag is used to encapsulate the electrode assembly 25 and the electrolyte. Specifically, the sealed bag can be a bag-shaped insulating member or an aluminum-plastic film. When the housing 22 is a sealed structure, it is used to encapsulate the electrode assembly 25, the electrolyte and other components.

[0082] As an example, the battery cell 21 can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. The prismatic battery cell includes a square shell battery cell, a blade-shaped battery cell, a polygonal battery, such as a hexagonal battery, etc. There is no special limitation in the present application.

[0083] The shell 22 may be provided with a liquid injection hole. During the assembly of the battery cell 21, the electrode assembly 25 may be first assembled into the shell 23, and then the electrolyte may be injected into the shell 22 through the liquid injection hole. After the electrolyte is injected, the electrode assembly 25 in the shell 22 needs to be fully wetted. After the electrolyte injection is completed, the liquid injection hole may be sealed to encapsulate the electrode assembly 25 and the electrolyte and other components.

[0084] In some embodiments, the housing 22 includes an end cap 24 and a shell 23, wherein the shell 23 is provided with an opening, and the end cap 24 is provided to cover the opening. The shell 23 may be provided with one or more openings. One or more end caps 24 may also be provided.

[0085] The battery cells or battery devices described in the embodiments of the present application are suitable for various electrical devices that use battery cells or battery devices, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, electric tools, vehicles, ships and spacecraft, for example, spacecraft include airplanes, rockets, space shuttles and spacecraft, etc.

[0086] like Figure 5 As shown, Figure 5 This is a flow chart of a method for testing the degree of electrolyte infiltration of a battery proposed in some embodiments of the present application. The present application provides a method for testing the degree of electrolyte infiltration of a battery, comprising:

[0087] S100: providing a battery cell soaked in electrolyte, wherein the battery cell comprises electrolyte and an electrode assembly soaked in the electrolyte, wherein the electrode assembly comprises a positive electrode sheet, a separator and a negative electrode sheet arranged in sequence.

[0088] S200: charging the battery cell soaked with electrolyte using a current of a preset charging rate and charging the battery cell to a preset capacity, wherein the current of the preset charging rate is greater than a calibrated charging current of the battery cell.

[0089] S300: Under a preset environment, obtaining a disassembled negative electrode sheet of a battery cell that has been charged.

[0090] S400: volatilizing the surface electrolyte of the disassembled negative electrode sheet under a preset environment.

[0091] S500: judging the electrolyte infiltration degree according to the surface grayscale information of the disassembled negative electrode sheet after the electrolyte volatilization is completed.

[0092] Among them, the positive electrode sheet, the separator and the negative electrode sheet can be stacked, the separator is arranged between the positive electrode sheet and the negative electrode sheet, and the separator is used to electrically insulate the adjacent positive electrode sheet and negative electrode sheet. The electrode assembly and the electrolyte can be both arranged in the outer shell of the battery cell. A battery cell that has been infiltrated with the electrolyte refers to a battery cell in which the electrolyte is injected into the shell of the battery cell, and after the electrolyte injection is completed, the battery cell is left to stand for a preset period of time. In short, a battery cell that has been infiltrated with the electrolyte is also a battery cell that needs to detect the degree of infiltration of the electrode assembly by the electrolyte. The separator can be an isolation membrane.

[0093] Before S100, the process also includes the step of preparing a battery cell soaked with electrolyte. The process of preparing a battery cell soaked with electrolyte generally includes winding or stacking a positive electrode sheet, a negative electrode sheet and a separator to form an electrode assembly, cold pressing the electrode assembly, assembling the cold pressed electrode assembly into a housing, and sequentially baking, injecting (injecting electrolyte into the housing), and soaking (soaking the electrode assembly with electrolyte) the semi-finished product after assembly to obtain a battery cell soaked with electrolyte.

[0094] The charge rate is a measure of charging speed, which refers to the current value required for the battery to be charged to its rated capacity within a specified time. Generally, the charge rate is expressed as C, and the charge rate C = charging current (A) / battery rated capacity (Ah). The larger the charge rate, the faster the battery charges and discharges. For example, if a battery with a capacity of 100A is charged with a current of 100A, the charge rate is 1C, which means it can be fully charged in 1 hour. If we charge with a current of 200A, the charge rate is 2C, and it can be fully charged in 30 minutes.

[0095] The calibrated charging current of a battery cell can be expressed as the charging rate of the battery cell, which refers to the calibrated current of the battery cell charging process, that is, the charging current that can maintain stable operation of the battery cell under the preset use environment. Taking into account the reliability of the battery cell during the charging process, the calibrated charging current of the battery cell is generally set to be less than 0.5 times the charging rate (0.5C), for example, it can be 0.33C. Among them, the preset use environment can be understood as the working environment in which the battery cell is actually used, which includes characteristics such as temperature and / or humidity. For example, the produced battery cells are planned to be used in vehicles, and the preset use environment corresponding to the battery cells can be understood as the climate environment of the area where the vehicle is located.

[0096] The preset charge rate is a pre-set charge rate, which can be adaptively adjusted according to the type of battery cell, and can be set to be greater than the calibrated charge rate of the battery cell to increase the embedding speed of active ions (such as lithium ions). Increasing the embedding speed of active ions (such as lithium ions) can shorten the time for charging the battery cell to the preset capacity, which can reduce the impact of the charging process on the electrolyte infiltration degree and improve the detection accuracy of the electrolyte infiltration degree.

[0097] Optionally, the charging time corresponding to the preset charging rate may be set to be shorter than the preset time for soaking the battery cells.

[0098] Exemplarily, the charging time corresponding to the preset charging rate may be 3 / 5 to 6 / 7 of the preset time for soaking the battery cells, for example, 6 / 7, 4 / 5, 3 / 4, 3 / 5, etc.

[0099] The preset capacity refers to the electric energy stored in the battery cell. The preset capacity may be the capacity measured for the battery cell of the current model. Under the preset capacity, the negative electrode sheet may have a more obvious color difference (ie, grayscale difference) after disassembly.

[0100] Optionally, the preset capacity is greater than or equal to 0.6 times the rated capacity of the battery cell.

[0101] The preset capacity can be 0.6 times the rated capacity (0.6SOC), 0.65 times the rated capacity (0.65SOC), 0.7 times the rated capacity (0.7SOC), etc. of the battery cell. SOC refers to the state of charge of the battery cell, that is, the remaining power. It represents the ratio of the remaining available power of the battery cell to the power in the fully charged state. This ratio is usually expressed as a percentage, ranging from 0 to 1. When SOC is 0, it means that the battery cell has been fully discharged; and when SOC is 1, it means that the battery cell is fully charged.

[0102] The limitation of preset capacity in this embodiment can make the disassembled negative electrode sheet of the battery cell charged to the preset capacity have a more obvious grayscale difference (the grayscale difference between the grayscale of the negative electrode sheet after active ions are embedded and the grayscale of the negative electrode sheet without active ions embedded), thereby improving the detection accuracy of the electrolyte infiltration degree.

[0103] Optionally, the preset capacity is less than or equal to 0.7 times the rated capacity of the battery cell. The preset capacity may range from 0.6 times to 0.7 times the rated capacity of the battery cell.

[0104] The limitation of preset capacity in this embodiment can make the disassembled negative electrode sheet of the battery cell charged to the preset capacity have a more obvious grayscale difference (the grayscale difference between the grayscale of the negative electrode sheet after active ions are embedded and the grayscale of the negative electrode sheet without active ions embedded), thereby improving the detection accuracy of the electrolyte infiltration degree, and eliminating the need to charge the battery cell to an excessively high capacity, saving electric energy and thus reducing testing costs.

[0105] S200 can be executed immediately after the battery cell is soaked. The shorter the interval from the completion of the soaking of the battery cell to the start of charging of the battery cell, the better. This interval can be controlled within 5 minutes, or within a range not exceeding 5% of the soaking time. This can reduce the impact on the soaking degree caused by the actual soaking time of the battery cell exceeding the preset time due to the interval time, thereby improving the detection accuracy of the electrolyte soaking degree.

[0106] During the testing process, devices such as reminders and timers can be set up. After the battery cell is soaked, reminder information can be sent to the tester to facilitate timely execution of corresponding testing steps.

[0107] S300 can be executed immediately after the battery cell is charged to a preset capacity. The disassembled negative electrode sheet is obtained by disassembling the charged battery cell. Exemplarily, S300 can be to disassemble the charged battery cell under a preset environment to separate the negative electrode sheet from the electrode assembly to obtain a disassembled negative electrode sheet. After the battery cell is charged to a preset capacity, the shorter the interval for disassembling the battery cell, the better. This interval can be controlled within 5 minutes, or within a range of no more than 5% of the charging time. This can reduce the possibility of reduced accuracy in detecting the degree of electrolyte wetting due to an excessively long interval.

[0108] During the testing process, devices such as reminders and timers can be set up. After the battery cells are charged to a preset capacity, reminder information can be sent to the tester to facilitate timely execution of corresponding testing steps.

[0109] The preset environment in S300 and S400 refers to an environment with a relatively suitable temperature and humidity, which can be a room temperature and a humidity of 0.2% to 0.4%. The humidity in this embodiment is a physical quantity of the dryness and wetness of the air, usually expressed as relative humidity, that is, the mass of water vapor contained in the air and the percentage of the mass of saturated water vapor at the same temperature. Appropriate temperature and humidity can reduce the impact of environmental factors on the grayscale of the disassembled negative electrode sheet, improve the detection accuracy of the electrolyte infiltration degree, and can increase the volatilization rate of the electrolyte and shorten the detection time of the electrolyte infiltration degree.

[0110] In S300, the disassembly of the battery cell includes opening the outer shell, taking out the electrode assembly from the outer shell, unfolding the electrode assembly, separating the negative electrode sheet from the separator (may also involve separating the separator from the positive electrode sheet), and obtaining a disassembled negative electrode sheet. In this process, the damage to the negative electrode sheet caused by the disassembly operation should be minimized, and the obtained disassembled negative electrode sheet should be as complete as possible, and the separators on both sides of the disassembled negative electrode sheet should be separated, so that both sides of the disassembled negative electrode sheet can be exposed.

[0111] In S400, the disassembled negative electrode sheet is spread out as flat as possible to improve the volatilization efficiency of the electrolyte. In S400, the disassembled negative electrode sheet can be naturally volatilized until the surface is dry under a preset environment.

[0112] In S500, illustratively, the tester may directly observe the surface grayscale information of the disassembled negative electrode sheet after the electrolyte volatilization is completed, and judge the electrolyte infiltration degree according to experience and requirements. illustratively, the surface image of the disassembled negative electrode sheet after the electrolyte volatilization is completed may be collected by an image acquisition component (such as a CCD camera, CCD is the abbreviation of charge coupled device), and the analysis device of the test equipment (the analysis device is an analysis and testing device such as a computer with information processing function) or the tester obtains the surface grayscale information of the disassembled negative electrode sheet based on the surface image of the disassembled negative electrode sheet, and judges the electrolyte infiltration degree based on the surface grayscale information of the disassembled negative electrode sheet.

[0113] The study found that when the electrode assembly is charged to a suitable capacity (preset capacity), the surface color of the negative electrode sheet after the active ions are embedded is different from the surface color of the negative electrode sheet without the active ions embedded. Correspondingly, in the image captured by the image acquisition component, the surface grayscale value of the negative electrode sheet after the active ions are embedded is different from the surface grayscale value of the negative electrode sheet without the active ions embedded. For example, in a lithium-ion battery cell, after the negative electrode sheet is embedded with lithium ions, its surface usually appears yellow, while the surface of the negative electrode sheet without the lithium ions embedded usually appears dark purple scars. In this way, the surface grayscale of the electrode sheet after the active ions are embedded is darker than the surface grayscale of the negative electrode sheet without the active ions embedded.

[0114] Among them, when judging the degree of electrolyte infiltration, the larger the area occupied by the grayscale region of the disassembled negative electrode sheet where active ions are not embedded on the surface of the negative electrode sheet, the lower the degree of electrolyte infiltration; conversely, the larger the area occupied by the grayscale region of the disassembled negative electrode sheet where active ions are embedded on the surface of the negative electrode sheet, the higher the degree of electrolyte infiltration.

[0115] The test method for the degree of electrolyte infiltration of a battery in the embodiment of the present application charges the battery cell by using a large current of a preset charging rate greater than a calibrated charging current, so that the active ions in the electrolyte are quickly embedded in the negative electrode sheet, and the negative electrode sheet of the electrode assembly is quickly charged to a preset capacity. After the surface electrolyte evaporates, there will be a color difference (i.e., grayscale difference) between the position where the active ions are embedded on the surface and the position where the active ions are not embedded. The degree of electrolyte infiltration on the electrode sheet can be intuitively obtained by disassembling the surface grayscale information of the surface of the negative electrode sheet. The operation is simple, and the degree of electrolyte infiltration can be reflected more accurately, thereby improving the detection accuracy. According to the more accurate detection results, the accuracy of selecting or adjusting relevant parameters of battery production can be improved, so that the electrolyte dispersion of the processed battery cell is more uniform, thereby improving the energy storage capacity, cycle performance and reliability of the battery device.

[0116] According to some embodiments of the present application, optionally, the preset charging rate is greater than or equal to 0.6 times the charging rate of the battery cell, and / or the preset capacity is set to 0.65 times the rated capacity of the battery cell.

[0117] The preset charging rate can be 0.6C, 0.65C, 0.7C, 0.75C, 0.8C or higher.

[0118] The limitation of the preset charging rate in this embodiment can increase the embedding speed of active ions (such as lithium ions) and shorten the time for charging the battery cells to the preset capacity, thereby reducing the impact of the charging process on the electrolyte infiltration degree and improving the detection accuracy of the electrolyte infiltration degree.

[0119] According to some embodiments of the present application, optionally, the preset charging rate is less than or equal to 0.8 times the charging rate of the battery cell.

[0120] The preset charging rate may range from 0.6C to 0.8C.

[0121] The limitation of the preset charging rate in this embodiment can increase the embedding speed of active ions (such as lithium ions) and shorten the time it takes for the battery cells to be charged to a preset capacity. At the same time, it can reduce the occurrence of situations such as rapid increase in heat of the battery cells due to excessive current, thereby improving the reliability of the battery cells during the test process.

[0122] According to some embodiments of the present application, optionally, the preset capacity is set to 0.65 times the rated capacity of the battery cell.

[0123] The limitation of preset capacity in this embodiment can make the disassembled negative electrode sheet of the battery cell charged to the preset capacity have a more obvious grayscale difference (the difference between the grayscale difference after the negative electrode sheet is embedded with active ions and the grayscale difference before the negative electrode sheet is not embedded with active ions), thereby improving the detection accuracy of the electrolyte infiltration degree, and eliminating the need to charge the battery cell to an excessively high capacity, saving electric energy and thus reducing testing costs.

[0124] According to some embodiments of the present application, optionally, the method for testing the degree of electrolyte wetting of a battery further includes determining a preset capacity of a battery cell. Figure 6 As shown, Figure 6 A flow chart of determining a preset capacity of a battery cell is provided for some embodiments of the present application. Determining the preset capacity of a battery cell includes:

[0125] S11: charging the multiple battery cells that have been soaked with the electrolyte using a current of a preset charging rate, and charging the multiple battery cells to different capacities respectively.

[0126] S12: Under a preset environment, obtaining separated negative electrode sheets of a plurality of battery cells that have completed charging.

[0127] S13: volatilize the electrolyte of the obtained separated negative electrode sheet under a preset environment.

[0128] S14: According to the surface grayscale information of each separated negative electrode sheet after the electrolyte has been volatilized, the capacity of the battery cell corresponding to the separated negative electrode sheet with the largest surface grayscale difference is selected as the preset capacity.

[0129] The grayscale difference is the difference between the grayscale corresponding to the negative electrode sheet without embedded active ions and the grayscale corresponding to the negative electrode sheet with embedded active ions.

[0130] The greater the grayscale difference, the more obvious the contrast, and the easier it is to observe. The separated negative electrode sheet with the largest grayscale difference is the separated negative electrode sheet with the most obvious grayscale contrast among the multiple separated negative electrode sheets.

[0131] In S11, each battery cell is a battery cell of the same model, each battery cell can be charged with the same current of the preset charging rate, and each battery cell is processed under the same processing conditions before the test. The charging capacity of multiple battery cells can be set in an equidistant gradient in sequence. In actual operation, a large difference charging capacity test can be performed first, and then a small difference test can be performed on the range near the charging capacity with obvious grayscale difference, and finally a more ideal preset capacity value range can be obtained.

[0132] Different types of battery cells may have different grayscale contrast ratios of negative electrode sheets at different capacities. When testing the electrolyte wettability of a battery cell, the preset capacity of the current battery cell can be determined through S11 to S14. In this way, during the electrolyte wettability test, the separated negative electrode sheet obtained can have a more obvious grayscale difference (the grayscale difference between the grayscale of the negative electrode sheet after the active ions are embedded and the grayscale of the negative electrode sheet without the active ions embedded), thereby improving the accuracy of the detection of the electrolyte wettability.

[0133] According to some embodiments of the present application, optionally, Figure 7 As shown, Figure 7 A flow chart for selecting the capacity of a battery cell corresponding to a separated negative electrode sheet with the largest grayscale difference as a preset capacity proposed in some embodiments of the present application, wherein the capacity of a battery cell corresponding to a separated negative electrode sheet with the largest grayscale difference is selected as the preset capacity, comprising:

[0134] S141: Select the separated negative electrode sheet with the largest grayscale difference.

[0135] S142: Selecting a separated negative electrode sheet having the largest grayscale difference between the grayscale at the center and the grayscale at both sides in the width direction, from the separated negative electrode sheets having the largest grayscale difference, and taking the capacity of the battery cell corresponding to the selected separated negative electrode sheet as the preset capacity.

[0136] The width direction is parallel to the direction in which the electrolyte infiltrates the separated negative electrode sheets during the process in which the electrolyte infiltrates the electrode assembly.

[0137] When the electrolyte infiltrates the electrode assembly, it infiltrates along the two ends of the electrode assembly toward the middle of the electrode assembly, and the width direction of the disassembled negative electrode sheet is consistent with the connection direction of the two ends of the electrode assembly. Figure 2 and Figure 3 As shown, when the electrode assembly is a winding structure, the width direction of the disassembled negative electrode sheet is perpendicular to the current paper surface (refer to Figure 2 X direction), that is, the axial direction of the winding structure; Figure 4 As shown, when the electrode assembly is a stacked structure, the width direction of the disassembled negative electrode sheet is also perpendicular to the direction of the current paper surface, and perpendicular to the stacking direction of the negative electrode sheet, the isolation membrane and the positive electrode sheet.

[0138] Before S11, during the infiltration process of multiple battery cells, the degree or path of electrolyte infiltration can be detected by perspective light, for example, by continuously monitoring the electrolyte infiltration process of the battery cells through X-rays (an electromagnetic wave with extremely high frequency, extremely short wavelength and large energy). According to the detection of the electrolyte by perspective light, the infiltration of the battery cells by the electrolyte can be stopped when the electrolyte has not completely moved to the center of the width direction of the negative electrode sheet, that is, the battery cells that have not been infiltrated at the center of the negative electrode sheet are used in S11, so that the center of the separated negative electrode sheet obtained in S13 is not embedded with active ions, while the two sides in the width direction of the separated negative electrode sheet are embedded with active ions, so that in S142, based on the difference between the grayscale at the center and the grayscale at the two sides, the separated negative electrode sheet with a more obvious difference in grayscale between the grayscale without embedded active ions and the grayscale embedded active ions can be selected.

[0139] According to the wetting path of the separated negative electrode sheet, after the active ions are embedded on both sides of the separated negative electrode sheet, there may still be an area in the center where the active ions are not embedded. Based on this characteristic, the area where the active ions are embedded and the area where the active ions are not embedded can be distinguished more clearly. Therefore, based on the difference between the grayscale at the center and the grayscale on both sides, the separated negative electrode sheet with obvious grayscale difference can be selected, and the reference significance of the selected separated negative electrode sheet is more accurate, which improves the accuracy of selecting the preset capacity, and further improves the accuracy of detecting the wetting degree of the battery cell.

[0140] According to some embodiments of the present application, optionally, Figure 8 As shown, Figure 8 The flowchart of soaking the battery cell proposed in some embodiments of the present application includes a step of soaking the battery cell before providing the battery cell soaked with electrolyte. The step of soaking the battery cell includes:

[0141] S21: Providing a battery assembly with a housing and an electrode assembly assembled.

[0142] S22: injecting electrolyte into the housing of the battery assembly to form a preformed battery cell.

[0143] S23: allowing the preformed battery cell to stand for a preset period of time, and detecting the infiltration path and infiltration completion degree of the electrolyte to the electrode assembly during the standing of the preformed battery cell.

[0144] Among them, the battery assembly is a semi-product of the battery cell, which can be understood as the assembly of the battery cell before the electrolyte is injected. The shell of the battery assembly can be provided with an injection hole, for example, the injection hole can be provided on the end cover, and the electrolyte can be injected into the shell through the injection hole. After the electrolyte is injected into the shell, the injection hole can be closed. The preformed battery cell is also a semi-product of the battery cell, which refers to the assembly after the electrolyte is injected during the battery cell assembly process.

[0145] In S23, the preset duration is a preset resting duration. Different preset durations can be set according to the test conditions, so that the relationship between the resting duration and the electrolyte infiltration degree can be tested. In S23, during the resting process of the preformed battery cell, the infiltration path and the degree of infiltration of the electrolyte to the electrode assembly are detected. It can be understood that during the resting process of the preformed battery cell, the infiltration of the electrolyte in the electrode assembly can be continuously monitored. It can be tested with the help of perspective light, for example, by X-rays (an electromagnetic wave with extremely high frequency, extremely short wavelength and high energy), the preformed battery cell is continuously monitored, or fluorescent substances are added to the electrolyte, and the fluorescence position is detected by perspective to detect the infiltration path and degree of infiltration of the electrolyte to the electrode assembly.

[0146] The infiltration path of the electrolyte to the electrode assembly can be roughly understood as the path of the electrolyte continuously penetrating in the electrode assembly. Studies have found that the electrode assembly is usually a typical gap-pore structure. According to the mass transfer theory of porous media, the driving force for electrolyte infiltration is capillary force, which is a spontaneous infiltration process. Due to the barrier of the current collector (for example, the copper-aluminum foil current collector of the lithium-ion battery monomer), the electrolyte infiltrates from the end face of the electrode assembly through the isolation membrane (i.e., the isolation member) into the interior of the electrode assembly. Therefore, the gap between the electrode assembly layers plays a guiding role, while the isolation membrane plays a diversion role. The steps or paths of electrolyte infiltration inside the electrode assembly are roughly as follows: the electrolyte is transmitted in the gap between the electrode piece and the isolation membrane under the action of capillary force; then, the electrolyte preferentially infiltrates in the pores of the isolation membrane (the electrolyte infiltration rate in the isolation membrane is much greater than that in the porous coating of the electrode piece); then, the electrolyte diffuses to the surfaces of the positive and negative electrode pieces on both sides through the isolation membrane and infiltrates into the pores of the porous electrode piece. During the static state of the preformed battery cell, the infiltration path of the electrolyte to the electrode assembly is detected to determine whether the electrolyte has infiltrated the expected path, which can serve as a reference for subsequent parameter adjustments and judgment of the performance of the battery cell.

[0147] The degree of wetting of the electrode assembly by the electrolyte also refers to the degree of wetting of the electrode assembly by the electrolyte, that is, the ratio of the part of the electrode assembly wetted by the electrolyte to the overall part of the electrode assembly. The higher this ratio is, the higher the degree of wetting is. During the standing process of the preformed battery cell, the degree of wetting of the electrode assembly by the electrolyte is detected, and the approximate degree of wetting of the electrode assembly by the electrolyte after the standing is completed can be known. This can provide a certain reference basis for subsequent testing of the degree of wetting of the electrolyte. In addition, at the end of the standing of the preformed battery cell, the degree of wetting of the electrode assembly by the electrolyte detected can be cross-referenced with the degree of wetting analyzed by S500, thereby improving the accuracy of detecting the degree of electrolyte wetting.

[0148] According to some embodiments of the present application, optionally, detecting the wetting path and wetting completion of the electrolyte to the electrode assembly includes: irradiating the preformed battery cell with X-rays and acquiring an image of the preformed battery cell, and analyzing the wetting path and wetting completion of the electrolyte to the electrode assembly based on the image.

[0149] X-rays can be provided by an X-ray device. The X-ray device can be connected to a controller such as a computer. The X-ray device irradiates the preformed battery cell with X-rays and obtains an image of the preformed battery cell after imaging processing. Through the image of the preformed battery cell that is continuously fed back during the static process, the infiltration path of the electrolyte to the electrode assembly and the infiltration completion degree of the current state can be known.

[0150] By visualizing the lithium ion binding with X-ray methods, the degree and path of electrolyte infiltration can be quantitatively characterized.

[0151] According to some embodiments of the present application, optionally, the humidity of the preset environment is 0.2% to 0.4%, and the temperature of the preset environment is 10° C. to 25° C.

[0152] Exemplarily, the humidity of the preset environment may be 0.2%, 0.3%, 0.4%, etc., and the temperature of the preset environment may be 10° C., 15° C., 20° C., 25° C., etc.

[0153] In S300, S400, S12 and S13, the preset environment can be an environment with a humidity of 0.2% to 0.4% and a temperature of 10°C to 25°C. In different steps, the preset environment can fluctuate, that is, as long as the humidity of the current environment is between 0.2% and 0.4%, and the temperature is between 10°C and 25°C. In the same step, the preset environment can also fluctuate, that is, as long as the humidity of the current environment is between 0.2% and 0.4%, and the temperature is between 10°C and 25°C.

[0154] The limitation of the preset environment in this embodiment can reduce the influence of environmental factors on the grayscale of the disassembled negative electrode sheet, improve the detection accuracy of the electrolyte infiltration degree, and increase the volatilization speed of the electrolyte, thereby shortening the detection time of the electrolyte infiltration degree.

[0155] According to some embodiments of the present application, optionally, the degree of electrolyte infiltration is judged based on the surface grayscale information of the disassembled negative electrode sheet after the electrolyte volatilization is completed, including: judging the degree of electrolyte infiltration based on the area of ​​the grayscale region of the disassembled negative electrode sheet where no active ions are embedded, or judging the degree of electrolyte infiltration based on the area of ​​the grayscale region of the disassembled negative electrode sheet where active ions are embedded.

[0156] Exemplarily, the degree of electrolyte infiltration can be judged based on the ratio of the area of ​​the grayscale region of the disassembled negative electrode sheet where no active ions are embedded to the surface area of ​​the disassembled negative electrode sheet; or, the degree of electrolyte infiltration can be judged based on the ratio of the area of ​​the grayscale region of the disassembled negative electrode sheet where active ions are embedded to the surface area of ​​the disassembled negative electrode sheet.

[0157] Among them, the smaller the ratio of the area of ​​the grayscale area of ​​the disassembled negative electrode sheet where active ions are not embedded to the surface area of ​​the disassembled negative electrode sheet, the larger the ratio of the area of ​​the grayscale area of ​​the disassembled negative electrode sheet where active ions are embedded to the surface area of ​​the disassembled negative electrode sheet, and the higher the degree of electrolyte infiltration.

[0158] The area of ​​the grayscale region of the disassembled negative electrode sheet where no active ions are embedded, the area of ​​the grayscale region of the disassembled negative electrode sheet where active ions are embedded, and the surface area of ​​the disassembled negative electrode sheet can be obtained by scanning the surface image of the negative electrode sheet and calculating.

[0159] Among them, when disassembling the surface area of ​​the negative electrode sheet, only the area of ​​the large surface of the negative electrode sheet used for contact with the isolation membrane is considered, and the thickness of the negative electrode sheet can be ignored. The surface area of ​​the negative electrode sheet can be disassembled to be the area of ​​a single side of the negative electrode sheet. Correspondingly, the area of ​​the grayscale area of ​​the negative electrode sheet not embedded with active ions and the area of ​​the grayscale area of ​​the negative electrode sheet embedded with active ions are also the areas of the corresponding areas of the single side of the negative electrode sheet. The surface area of ​​the negative electrode sheet can be disassembled to be the area of ​​both sides of the negative electrode sheet. Correspondingly, the area of ​​the grayscale area of ​​the negative electrode sheet not embedded with active ions and the area of ​​the grayscale area of ​​the negative electrode sheet embedded with active ions are also the areas of the corresponding areas of the double sides of the negative electrode sheet.

[0160] Using the area as a reference value for judgment is more intuitive and improves the detection efficiency and accuracy of the electrolyte infiltration degree.

[0161] According to some embodiments of the present application, optionally, the degree of electrolyte infiltration is judged according to the surface grayscale information of the disassembled negative electrode sheet after the electrolyte volatilization is completed, including: according to the presence of a grayscale area in which the disassembled negative electrode sheet is not embedded with active ions at the center of the disassembled negative electrode sheet along its own width direction, and the unit area of ​​the grayscale area in which the active ions are not embedded is greater than or equal to a preset unit area, confirming that the electrolyte infiltration is not completed; according to the absence of a grayscale area in which the disassembled negative electrode sheet is not embedded with active ions at the center of the disassembled negative electrode sheet along its own width direction, or the presence of a grayscale area in which the active ions are not embedded at the center of the disassembled negative electrode sheet along its own width direction, and the unit area of ​​the grayscale area in which the active ions are not embedded is less than a preset unit area, confirming that the electrolyte infiltration is completed; in the process of the disassembled negative electrode sheet's own width direction and the electrolyte infiltration direction of the electrode assembly, the electrolyte is parallel to the disassembled negative electrode sheet.

[0162] The preset unit area is a preset reference value, which can be zero or other smaller positive values. When the grayscale area of ​​the disassembled negative electrode sheet along the center of its own width direction is greater than or equal to the preset unit area, it can be considered that the electrolyte has not moved to the center of the disassembled negative electrode sheet along its own width direction, so the infiltration has not been completed; when there is no grayscale area of ​​the disassembled negative electrode sheet along the center of its own width direction, it means that the electrolyte has moved to the center of the disassembled negative electrode sheet along its own width direction and has completed the infiltration of the center, so it can be considered that the infiltration is completed; when there is a grayscale area of ​​the disassembled negative electrode sheet along the center of its own width direction, and the unit area of ​​the grayscale area of ​​the disassembled negative electrode sheet is less than the preset unit area, it means that the electrolyte has moved to the center of the disassembled negative electrode sheet along its own width direction, and the local center may not be infiltrated due to bubbles and other reasons, so the infiltration can also be completed at this time.

[0163] It should be noted that when the infiltration of the center of the disassembled negative electrode sheet along its width direction is completed or basically completed, there may still be gray areas in other areas of the disassembled negative electrode sheet where the active ions are not embedded. These gray areas of the negative electrode sheet where active ions are not embedded may be due to insufficient infiltration caused by defects such as bubbles, resulting in a decrease in the degree of electrolyte. At this time, the degree of electrolyte infiltration can be reasonably judged based on the judgment of the area of ​​the gray area.

[0164] By disassembling the gray area at the center of the negative electrode sheet along its width direction, it can be more accurately determined whether the electrolyte infiltration is complete.

[0165] This embodiment provides a method for testing the degree of electrolyte infiltration in a battery. The corresponding battery is a wound lithium-ion battery cell, which includes a positive electrode sheet, a negative electrode sheet, a separator, an electrolyte and a shell. The positive electrode sheet, the negative electrode sheet and the separator are all continuous, and the prepared positive electrode sheet, the negative electrode sheet and the separator are assembled into an electrode assembly in a winding manner. The two electrode assemblies are paired and assembled into the shell to form a square battery cell. The square battery cell is vacuum baked and injected once to form a battery cell infiltrated with electrolyte. The infiltrated battery cell is charged to 65% SOC using a 0.6C high current formation. After charging, the battery cell is immediately disassembled under a preset environment, the electrode assembly is taken out and unfolded, the positive electrode sheet and the separator are separated from the negative electrode sheet, and the preset environment is continued to be maintained. The disassembled negative electrode sheet is laid flat on the table, and the electrolyte of the disassembled negative electrode sheet evaporates naturally. The degree and path of electrolyte infiltration are judged by measuring the area of ​​the purple spot dark mark in the middle after the electrolyte evaporates.

[0166] Among them, the production process of the positive electrode sheet of a lithium-ion battery monomer can be roughly as follows: lithium iron phosphate, conductive carbon black and PVDF (polyvinylidene fluoride) are mixed in a mass ratio of 8:1:1, and a solvent N-methylpyrrolidone (C5H9NO) is added to make a positive electrode active material, and the positive electrode active material is coated on both sides of the aluminum foil, and after cold pressing and cutting, a positive electrode sheet is obtained, and the positive electrode sheet is rolled into a film roll, and a ceramic slurry is sprayed on the cut surface of the film roll. In the ceramic slurry, the ceramic material is boehmite, accounting for 39wt% (wt% is the mass percentage); the binder is polyacrylate, accounting for 5wt%; the solvent is N-methylpyrrolidone, the solid content of the slurry is 10%, and the viscosity of the slurry is 800mPa·s (mPa·s, megapascal seconds, the unit of viscosity).

[0167] The production process of the negative electrode sheet can be roughly as follows: artificial graphite, conductive carbon black, binder carboxymethyl cellulose (CMC) and solvent water are evenly mixed in a weight ratio of 95:2:3:100 to make a negative electrode coating, the negative electrode coating is applied on both sides of the copper foil, and after cold pressing and cutting, the negative electrode sheet is obtained.

[0168] The manufacturing process of the isolation film can be roughly as follows: a polyethylene film with a thickness of 10 μm (μm, micrometer, unit of length) is used as the isolation film.

[0169] The preparation process of the electrolyte solution can be roughly as follows: ethylene carbonate, diethyl carbonate, and dimethyl carbonate are mixed in a volume ratio of 1:1:1, and LiPF6 (lithium hexafluorophosphate) is dissolved in the above solution to obtain an electrolyte solution. In the electrolyte solution, the concentration of LiPF6 is 1 mol / L (mole per liter, a concentration unit).

[0170] The assembly of the electrode assembly is roughly as follows: the separator, negative electrode sheet, separator, and positive electrode sheet are placed in the order of separation film, one end of the positive electrode sheet, negative electrode sheet, and two separators are fixed to the discharge roller, and the other end is stacked together and fixed to the winding shaft. The winding shaft is rotated by a motor to wind up the positive electrode sheet, negative electrode sheet, and two separators to obtain a wound electrode assembly.

[0171] For the above-mentioned battery cells, before conducting experimental tests, the ideal preset capacity of the battery cells after vacuum baking, one-time injection, and electrolyte infiltration for a preset time (e.g., two hours) can be verified. It can be done by charging multiple battery cells with a large formation current, disassembling the battery cells separately, obtaining disassembled negative electrode sheets, and then determining the size of the purple spots and dark marks in the middle of the interface of the disassembled negative electrode sheets to determine the appropriate preset capacity that characterizes the degree and path of electrolyte infiltration of the electrode sheets. Fig. 9 As shown, Fig. 9 What is shown is a table showing the relationship between the charging capacity of a battery cell and the surface grayscale information of a disassembled negative electrode sheet. This embodiment shows the surface grayscale information of the disassembled negative electrode sheets of seven battery cells with different charging capacities. The first battery cell is charged to 21% SOC, the second battery cell is charged to 45% SOC, the third battery cell is charged to 55% SOC, the fourth battery cell is charged to 65% SOC, the fifth battery cell is charged to 70% SOC, the sixth battery cell is charged to 80% SOC, and the seventh battery cell is charged to 90% SOC. Through actual verification and comparison, it can be seen that when a battery cell can be charged to 65% SOC, its color difference (i.e., grayscale difference) is large, and the display rule of its color information (i.e., grayscale information) is more consistent with the theoretical infiltration path of the electrolyte. Therefore, the battery cell can be determined to be charged to 65% SOC with a large current, and the infiltration degree and path of the electrolyte can be characterized at different electrolyte infiltration times.

[0172] After determining the appropriate preset capacity that can accurately characterize the electrolyte infiltration degree and path, the appropriate infiltration time to characterize the cold pressing parameters can be found by verifying the infiltration time of different electrolytes and disassembling the battery cells. Fig.10 As shown, Fig.10The table shows the relationship between the immersion time of the electrode assembly and the electrolyte immersion degree. When the immersion time is different and other preparation conditions (including cold pressing parameters, cold pressing pressure and other parameters) are the same, the influence of different immersion times on the electrolyte immersion degree can be obtained. Fig.10 Only part of the test results are shown, including the color information (i.e. grayscale information) of the disassembled negative electrode sheet after immersion for 2.5 hours, 6.5 hours, 12.5 hours and 24.5 hours. Among them, the third fold represents the current part (the current part is Fig.10 The part of the disassembled negative electrode sheet shown above) is the third layer of the negative electrode sheet in the wound electrode assembly, and the 10th fold represents the current part (the current part is Fig.10 The position of the disassembled negative electrode sheet shown above) is the 10th layer of the negative electrode sheet in the wound electrode assembly, and the 12th fold represents the current position (the current position is Fig.10 The position of the disassembled negative electrode sheet shown above) is the 12th layer of the negative electrode sheet in the wound electrode assembly, and the 31st fold represents the current position (the current position is Fig.10 The position of the disassembled negative electrode sheet shown above is the 31st layer of the negative electrode sheet in the wound electrode assembly, and the 32nd fold represents the current position (the current position is Fig.10 The part of the disassembled negative electrode sheet shown above is the 32nd layer of the negative electrode sheet in the wound electrode assembly. Through actual verification, it can be seen that when the battery cell is charged to 65% SOC, the purple spot marks in the middle can be clearly seen after immersion for 2.5h (hours), 6.5h, 2.5h, and 24.5h, which can truly reflect the immersion effect of industrial production. For the electrode assembly of this embodiment, 2 hours was finally selected as a more appropriate preset immersion time.

[0173] Furthermore, by keeping the cold pressing time of the electrode assembly unchanged and changing the cold pressing pressure of the electrode assembly, it is verified that after the battery cell has been vacuum-baked, injected once, and the electrode assembly has been soaked for 2 hours, it is charged to 65% SOC with a large current, and the interface of the negative electrode sheet (i.e., the surface where the negative electrode sheet contacts the separator) is disassembled to determine the effect of the cold pressing time on the electrolyte soaking degree and path. Fig.11 As shown, Fig.11 The table shows the relationship between the cold pressing time of the electrode assembly and the electrolyte infiltration degree. Fig.11 Only part of the test results are shown, which are partial data of the cold pressing pressure of the electrode assembly being 9T (tons) and the cold pressing time being 10S (seconds), 20S and 30S.

[0174] It is also possible to maintain the cold pressing pressure of the electrode assembly unchanged, change the cold pressing time of the electrode assembly, verify that after the battery cell has been vacuum baked, injected once, and the electrode assembly has been soaked for 2 hours, it is charged to 65% SOC with a large current, and the interface of the negative electrode sheet is disassembled to determine the effect of the cold pressing pressure on the electrolyte soaking degree and path. Fig.12As shown, Fig.12 The table shows the relationship between the cold pressing pressure of the electrode assembly and the electrolyte infiltration degree. Fig.11 Only part of the test results are shown, which are partial data of the electrode assembly with a cold pressing time of 10S and cold pressing pressures of 8.6T (ton), 9T and 9.4T respectively.

[0175] Based on the above tests, it can be seen that the cold pressing parameters of the electrode assembly will affect the electrolyte infiltration, and the cold pressing parameters such as cold pressing pressure and cold pressing time are the key factors affecting the electrolyte infiltration. It can be summarized as follows: for the same cold pressing time, the greater the cold pressing pressure of the bare cell, the larger the dark mark area in the middle of the negative electrode interface will be, and the worse the electrolyte infiltration effect will be. For the same cold pressing pressure, the longer the cold pressing time of the electrode assembly, the larger the dark mark area in the middle of the negative electrode interface will be, and the worse the electrolyte infiltration effect will be.

[0176] like Fig.13 As shown, Fig.13 This is a schematic diagram of a battery electrolyte infiltration degree testing device proposed in some embodiments of the present application. The embodiments of the present application also provide a battery electrolyte infiltration degree testing device, including a preparation device 610, a charging device 620, a volatilization device 640 and an analysis device 650. The preparation device 610 is used to provide a battery cell that has been soaked in electrolyte, the battery cell includes an electrolyte and an electrode assembly soaked in the electrolyte, the electrode assembly includes a positive electrode sheet, a separator and a negative electrode sheet arranged in sequence; the charging device 620 is used to charge the battery cell that has been soaked in electrolyte with a current of a preset charging rate and charge it to a preset capacity; the disassembly device 630 is used to obtain the disassembled negative electrode sheet of the charged battery cell under a preset environment; the volatilization device 640 is used to support the disassembled negative electrode sheet and volatilize the surface electrolyte of the disassembled negative electrode sheet under a preset environment; the analysis device 650 is used to obtain the surface grayscale information of the disassembled negative electrode sheet after the electrolyte volatilization, and judge the degree of electrolyte infiltration based on the surface grayscale information of the disassembled negative electrode sheet after the electrolyte volatilization.

[0177] The battery electrolyte infiltration degree testing device of this embodiment is used to execute the battery electrolyte infiltration degree testing method proposed in this application or any embodiment of this application.

[0178] The preparation device 610 is used to perform S100 , and the preparation device 610 may include a liquid injection mechanism for injecting electrolyte into the housing, a stationary component for supporting the battery cell and making the battery cell stationary, and the like.

[0179] The charging device 620 is used to execute S200 , and the charging device 620 may include a voltage and / or current detection component, a voltage and / or current conversion component, a power line component connected to a power source, and the like.

[0180] The disassembly device 630 is used to perform S300. The disassembly device 630 can be set in a preset environment, or the disassembly device 630 can create a preset environment. The disassembly device 630 can include a disassembly component for destroying the shell, a component for separating the negative electrode sheet, the separator and the positive electrode sheet, a component for unfolding the negative electrode sheet, etc.

[0181] The volatilization device 640 is used to perform S400, and the volatilization device 640 can be set in a preset environment, or the disassembly device 630 can create a preset environment. The volatilization device 640 can include a support table for supporting the separation of the negative electrode sheet or the disassembly of the negative electrode sheet, and the support table can be a desktop or the like.

[0182] The analysis device 650 is used to execute S500. The analysis device 650 has functions such as data receiving and processing. It may include a CCD camera and a computer. The CCD camera is used to obtain images of disassembled negative electrode sheets or separated negative electrode sheets. The computer is used to receive images captured by the CCD camera, and process the surface grayscale information of the disassembled negative electrode sheets or separated negative electrode sheets obtained through the images, and determine the degree of electrolyte infiltration.

[0183] The battery electrolyte infiltration degree testing device of the embodiment of the present application has the same beneficial effects as the battery electrolyte infiltration degree testing method proposed in the present application or any embodiment of the present application.

[0184] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0185] The above description of various embodiments tends to emphasize the differences between the various embodiments. The same or similar aspects can be referenced to each other, and for the sake of brevity, they will not be repeated herein.

[0186] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A method for testing the degree of battery electrolyte infiltration, characterized in that: include: Providing a battery cell soaked in an electrolyte, wherein the battery cell comprises an electrolyte and an electrode assembly soaked in the electrolyte, wherein the electrode assembly comprises a positive electrode sheet, a separator and a negative electrode sheet arranged in sequence; Using a current of a preset charging rate to charge the battery cell that has been soaked with the electrolyte to a preset capacity, the current of the preset charging rate being greater than a calibrated charging current of the battery cell; Under a preset environment, obtaining a disassembled negative electrode sheet of a battery cell that has been charged; Allowing the disassembled negative electrode sheet to volatilize the surface electrolyte under the preset environment; The electrolyte infiltration degree is determined based on the surface grayscale information of the disassembled negative electrode sheet after the electrolyte has been volatilized.

2. The method for testing the degree of battery electrolyte infiltration according to claim 1, characterized in that: The preset charging rate is greater than or equal to 0.6 times the charging rate of the battery cell, and / or the preset capacity is set to 0.65 times the rated capacity of the battery cell.

3. The method for testing the degree of battery electrolyte infiltration according to claim 1 or 2, characterized in that: The method for testing the degree of electrolyte infiltration of the battery further includes: determining the preset capacity of the battery cell, including: Using the current of the preset charging rate to charge the multiple battery cells that have been soaked with the electrolyte, and the multiple battery cells are charged to different capacities respectively; Under the preset environment, obtaining the separated negative electrode sheets of the plurality of battery cells that have completed charging; Allowing the obtained separated negative electrode sheet to volatilize the electrolyte under the preset environment; According to the surface grayscale information of each separated negative electrode sheet after the electrolyte volatilization is completed, the capacity of the battery cell corresponding to the separated negative electrode sheet with the largest grayscale difference is selected as the preset capacity, and the grayscale difference is the difference between the grayscale corresponding to the negative electrode sheet without active ions embedded and the grayscale corresponding to the negative electrode sheet with active ions embedded.

4. The method for testing the degree of battery electrolyte infiltration according to claim 3, characterized in that: The step of selecting the capacity of the battery cell corresponding to the separated negative electrode sheet having the largest grayscale difference as the preset capacity includes: Selecting the separated negative electrode sheet with the largest grayscale difference; From the separated negative electrode sheets with the largest grayscale difference, select the separated negative electrode sheet with the largest difference between the grayscale at the center and the grayscale on both sides in the width direction, and use the capacity of the battery cell corresponding to the selected separated negative electrode sheet as the preset capacity. The width direction is parallel to the wetting direction of the electrolyte on the separated negative electrode sheet during the process of the electrolyte infiltrating the electrode assembly.

5. The method for testing the degree of battery electrolyte infiltration according to claim 1 or 2, characterized in that: Before providing the battery cell soaked with electrolyte, the method further includes: soaking the battery cell, including: Providing a battery assembly with a housing and an electrode assembly assembled; injecting electrolyte into the housing of the battery assembly to form a preformed battery cell; The preformed battery cell is allowed to stand for a preset time, and during the standing time of the preformed battery cell, the infiltration path and infiltration completion degree of the electrolyte to the electrode assembly are detected.

6. The method for testing the degree of battery electrolyte infiltration according to claim 5, characterized in that: The detecting of the infiltration path and the degree of infiltration completion of the electrolyte to the electrode assembly includes: irradiating the preformed battery cell with X-rays and acquiring an image of the preformed battery cell, and analyzing the infiltration path and the degree of infiltration completion of the electrolyte to the electrode assembly based on the image.

7. The method for testing the degree of battery electrolyte infiltration according to claim 1 or 2, characterized in that: The humidity of the preset environment is 0.2% to 0.4%, and the temperature of the preset environment is 10° C. to 25° C.

8. The method for testing the degree of battery electrolyte infiltration according to claim 1 or 2, characterized in that: The step of judging the electrolyte infiltration degree according to the surface grayscale information of the disassembled negative electrode sheet after the electrolyte volatilization is completed includes: The electrolyte infiltration degree is determined according to the area of ​​the grayscale region of the disassembled negative electrode sheet where no active ions are embedded, or according to the area of ​​the grayscale region of the disassembled negative electrode sheet where active ions are embedded.

9. The method for testing the degree of battery electrolyte infiltration according to claim 1 or 2, characterized in that: The step of judging the electrolyte infiltration degree according to the surface grayscale information of the disassembled negative electrode sheet after the electrolyte volatilization is completed includes: According to the grayscale area without active ions embedded in the center of the disassembled negative electrode sheet along its width direction, and the unit area of ​​the grayscale area without active ions embedded in it is greater than or equal to the preset unit area, it is confirmed that the electrolyte has not yet been completely infiltrated, wherein the width direction of the disassembled negative electrode sheet is parallel to the infiltration direction of the electrolyte to the disassembled negative electrode sheet during the process of the electrolyte infiltrating the electrode assembly; According to the fact that there is no gray area in which active ions are not embedded at the center of the disassembled negative electrode sheet along its own width direction, or that there is a gray area in which active ions are not embedded at the center of the disassembled negative electrode sheet along its own width direction, and the unit area of ​​the gray area in which active ions are not embedded is smaller than the preset unit area, it is confirmed that the electrolyte infiltration is completed.

10. A battery electrolyte infiltration degree testing device, characterized in that: include: A preparation device for providing a battery cell soaked with an electrolyte, wherein the battery cell comprises an electrolyte and an electrode assembly soaked in the electrolyte, wherein the electrode assembly comprises a positive electrode sheet, a separator and a negative electrode sheet arranged in sequence; A charging device, used to charge the battery cells soaked with electrolyte using a current of a preset charging rate and charge them to a preset capacity; A disassembly device, used to obtain the disassembled negative electrode sheet of a battery cell that has been charged under a preset environment; A volatilization device, used for supporting the disassembled negative electrode sheet and allowing the disassembled negative electrode sheet to volatilize the surface electrolyte under the preset environment; The analysis device is used to obtain the surface grayscale information of the disassembled negative electrode sheet after the electrolyte volatilization is completed, and judge the electrolyte infiltration degree according to the surface grayscale information of the disassembled negative electrode sheet after the electrolyte volatilization is completed.

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