Battery cell infiltration condition acquisition method, device, equipment, medium and product

Abstract

The invention discloses a method, a device and equipment for acquiring the infiltration condition of a battery cell, a medium and a product, and relates to the field of battery preparation. The method comprises the following steps: collecting a first infiltration cross section corresponding to the end part of the battery cell and a second infiltration cross section corresponding to the middle part of the battery cell in the electrolyte infiltration process of the cylindrical battery cell; acquiring a first concentricity corresponding to the end part of the battery cell based on the first infiltration cross section, and acquiring a second concentricity corresponding to the middle part of the battery cell based on the second infiltration cross section; and displaying the infiltration condition of the cylindrical battery cell based on the difference condition between the first concentricity and the second concentricity. According to the method, the deviation change condition of the roll core center relative to the center of the shell can be flexibly analyzed by virtue of the change of concentricity, the condition that the cylindrical battery core is infiltrated by electrolyte can be known in time, the purpose of nondestructive detection of the cylindrical roll core wettability is achieved, and the infiltration time of the cylindrical battery core can be effectively mastered. The method can be applied to various scenes such as a battery safety evaluation scene and a battery state prediction scene.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of battery preparation, and in particular to a method, device, equipment, medium and product for obtaining the wetting condition of a battery cell. Background Art

[0002] Battery technology is an indispensable component of modern electronic devices and energy storage systems. Batteries are used in many scenarios. Cylindrical cells are a form of battery, an electrochemical device that can convert chemical energy into electrical energy.

[0003] In the related art, the cylindrical battery cell is protected by a metal shell. If effective online detection is required during the production process of the cylindrical battery cell, it is usually necessary to destroy and disassemble the cylindrical battery cell offline to observe the absorption of the electrolyte by the diaphragm in the cylindrical battery cell at different times to determine whether the winding core in the cylindrical battery cell has been fully infiltrated.

[0004] However, the above method requires destroying the cylindrical battery cell, and the wetting status of the positive and negative electrodes cannot be observed, and can only be determined through the diaphragm, which not only causes cost waste, but also wastes time in disassembly, and cannot effectively achieve the purpose of online control. Summary of the invention

[0005] The embodiments of the present application provide a method, device, equipment, medium and product for obtaining the wettability of a battery cell, which can flexibly analyze the offset change of the center of the core relative to the center of the shell by means of the change of concentricity, timely understand the situation of electrolyte infiltration of the cylindrical battery cell, achieve the purpose of non-destructive detection of the wettability of the cylindrical core, and also help to effectively grasp the wettability time of the cylindrical battery cell. The technical solution is as follows.

[0006] On the one hand, a method for obtaining the wetting condition of a battery cell is provided, the method comprising:

[0007] Collecting a first infiltration cross section corresponding to the end of the cylindrical battery cell during the electrolyte infiltration process; and collecting a second infiltration cross section corresponding to the middle of the cylindrical battery cell during the electrolyte infiltration process; wherein the cylindrical battery cell comprises a winding core and a metal shell, the metal shell is used to wrap the winding core, and the outer diameter of the winding core is smaller than the inner diameter of the metal shell;

[0008] Based on the first wetted cross section, a first concentricity corresponding to the end of the battery cell is obtained, and based on the second wetted cross section, a second concentricity corresponding to the middle of the battery cell is obtained; wherein the concentricity is used to characterize the degree of deviation of the center of the winding core relative to the center of the shell in the wetted cross section;

[0009] Based on the difference between the first concentricity and the second concentricity, the wetting condition of the cylindrical battery core is displayed, and the wetting condition is used to characterize the degree to which the electrolyte infiltrates the cylindrical battery core.

[0010] On the other hand, a device for obtaining the wetting condition of a battery cell is provided, the device comprising:

[0011] A collection module, used to collect a first infiltration cross section corresponding to the end of the cylindrical battery cell during the electrolyte infiltration process; and to collect a second infiltration cross section corresponding to the middle of the cylindrical battery cell during the electrolyte infiltration process; wherein the cylindrical battery cell comprises a winding core and a metal shell, the metal shell is used to wrap the winding core, and the outer diameter of the winding core is smaller than the inner diameter of the metal shell;

[0012] An acquisition module, configured to acquire a first concentricity corresponding to the end of the battery cell based on the first wetted cross section, and to acquire a second concentricity corresponding to the middle of the battery cell based on the second wetted cross section; wherein the concentricity is used to characterize the degree of deviation of the center of the winding core relative to the center of the shell in the wetted cross section;

[0013] The display module is used to display the wetting condition of the cylindrical battery core based on the difference between the first concentricity and the second concentricity, and the wetting condition is used to characterize the degree to which the electrolyte infiltrates the cylindrical battery core.

[0014] On the other hand, a computer device is provided, comprising a processor and a memory, wherein the memory stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set are loaded and executed by the processor to implement a method for obtaining the wetness condition of a battery cell as described in any of the above-mentioned embodiments of the present application.

[0015] On the other hand, a computer-readable storage medium is provided, in which at least one instruction, at least one program, a code set or an instruction set is stored. The at least one instruction, the at least one program, the code set or the instruction set is loaded and executed by a processor to implement a method for obtaining the wetting condition of a battery cell as described in any of the above-mentioned embodiments of the present application.

[0016] On the other hand, a computer program product or a computer program is provided, the computer program product or the computer program includes computer instructions, the computer instructions are stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device executes the method for obtaining the cell wetness condition described in any of the above embodiments.

[0017] The beneficial effects brought by the technical solution provided by the embodiment of the present application include at least:

[0018] In the process of the cylindrical battery cell being infiltrated by the electrolyte, the first concentricity of the end of the battery cell and the second concentricity of the middle of the battery cell are obtained according to the degree of offset of the center of the core relative to the center of the shell in the infiltration cross section corresponding to the cylindrical battery cell, so as to analyze the degree of electrolyte infiltration into the cylindrical battery cell according to the difference between the first concentricity and the second concentricity to display the infiltration condition of the cylindrical battery cell. With the help of the change of concentricity, the offset change of the center of the core relative to the center of the shell can be flexibly analyzed, so as to flexibly determine the degree of electrolyte infiltration into the cylindrical battery cell. It helps to understand the situation of electrolyte infiltration into the cylindrical battery cell more timely, realize the purpose of non-destructive testing of the wettability of the cylindrical core, avoids the problem of needing to destroy the cylindrical battery cell to analyze the degree of infiltration, and also helps to effectively grasp the infiltration time of the cylindrical battery cell and improve the processing efficiency of the cylindrical battery cell infiltration process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 is a structural block diagram of a situation acquisition system provided by an exemplary embodiment of the present application;

[0021] Figure 2 is a flow chart of a method for obtaining the wetting condition of a battery cell provided by an exemplary embodiment of the present application;

[0022] Figure 3 is a flow chart of a method for obtaining the wetting condition of a battery cell provided by another exemplary embodiment of the present application;

[0023] Figure 4 is a flow chart of a method for obtaining the wetting condition of a battery cell provided by another exemplary embodiment of the present application;

[0024] Figure 5 is a flow chart of a method for obtaining the wetting condition of a battery cell provided by another exemplary embodiment of the present application;

[0025] Figure 6 is a schematic cross-sectional view of a cylindrical battery cell before impregnation provided by an exemplary embodiment of the present application;

[0026] Figure 7 is a schematic cross-sectional view of a cylindrical battery cell after impregnation provided by an exemplary embodiment of the present application;

[0027] Figure 8 is a flow chart of analyzing infiltration conditions at multiple evaluation moments provided by an exemplary embodiment of the present application;

[0028] Fig. 9 is a flow chart of obtaining a wetting curve based on multiple evaluation moments provided by an exemplary embodiment of the present application;

[0029] Fig.10 is a structural block diagram of a device for obtaining a cell wetting condition provided by an exemplary embodiment of the present application;

[0030] Fig.11 It is a structural block diagram of a terminal provided by an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0032] First, a brief introduction is given to the terms involved in the embodiments of the present application.

[0033] Cylindrical cells: Cylindrical cells are a common form of battery, especially in portable electronic devices and electric vehicles. The design of cylindrical cells usually includes a cylindrical metal shell, which contains key components such as positive electrode materials, negative electrode materials, separators, electrolytes, etc. Cylindrical cells are widely used in various electronic products due to their standardized size and reliable performance, such as laptops, digital cameras, portable tools, and an increasing number of electric vehicles and large energy storage systems.

[0034] Metal casing: Usually made of metal materials such as steel or aluminum, the metal casing not only provides physical protection, but also acts as a current collector for the positive electrode material or the negative electrode material. The main function of the current collector is to collect the charge in the electrode material (positive electrode material or negative electrode material) and transmit the charge through the external circuit of the battery. At the same time, it can also transfer the charge of the external circuit to the electrode material.

[0035] Positive electrode material: During the discharge process of the battery, the positive electrode material provides lithium ions (or other charge carriers), and the lithium ions move to the negative electrode material through the electrolyte. During the charging process, the lithium ions return from the negative electrode material to the positive electrode material. Positive electrode materials generally have a high redox potential, which means that they can easily release and accept electrons. Common positive electrode materials in lithium-ion batteries include lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium iron phosphate (LiFePO4), nickel cobalt aluminum oxide (NCA), etc.

[0036] Negative electrode materials: During the discharge process of the battery, the negative electrode material receives lithium ions from the positive electrode material and releases lithium ions back to the positive electrode material during the charging process. The negative electrode material needs to have a high lithium storage capacity and good conductivity. Negative electrode materials usually have a low redox potential, which allows them to easily embed and deintercalate lithium ions. Common negative electrode materials in lithium-ion batteries include graphite (such as artificial graphite, natural graphite), carbon-based materials, silicon-based materials, tin-based materials, lithium titanate (Li4Ti5O12), etc.

[0037] Diaphragm: Diaphragm is one of the key components of lithium-ion batteries. It is located between the positive and negative electrodes of the battery. Its main function is to prevent physical contact between the positive and negative electrodes, thereby avoiding short circuits, while allowing lithium ions to pass through and stably conduct lithium ions to complete the battery's charge and discharge cycle. The diaphragm is usually a functional membrane material with a microporous structure, and the quality of its performance directly determines the overall performance of the battery. The materials of the diaphragm usually include polyolefins, such as polyethylene (PE) and polypropylene (PP), as well as microporous membranes prepared by dry or wet processes. In addition, there are composite diaphragms that improve the thermal stability and safety of the diaphragm by coating inorganic ceramic particles (such as alumina) on polyolefin-based membranes. New diaphragm materials are also under continuous development, including fluoropolymers, cellulose, polyimide (PI), polyester (PET), etc.

[0038] Electrolyte: The electrolyte is an organic solvent containing lithium salts, which conducts lithium ions between the positive and negative electrodes, allowing the battery to perform charge and discharge cycles. During the electrolyte infiltration process, both the diaphragm and the electrode materials are infiltrated to ensure that lithium ions can be freely transmitted inside the battery, thereby completing the charge and discharge process. The uniformity and sufficiency of the infiltration have an important impact on the performance of the battery.

[0039] In the related art, the cylindrical battery cell is protected by a metal shell. If effective online detection is required during the production process of the cylindrical battery cell, it is usually necessary to destroy and disassemble the cylindrical battery cell offline to observe the absorption of electrolyte by the diaphragm inside the cylindrical battery cell at different times to determine whether the winding core inside the cylindrical battery cell has been fully wetted. However, the above method requires the destruction of the cylindrical battery cell, and the wetting state of the positive and negative electrodes cannot be observed. It can only be determined by the diaphragm, which not only causes cost waste, but also wastes time in disassembly, and cannot effectively achieve the purpose of online control.

[0040] In an embodiment of the present application, a method for obtaining the wetting condition of a battery cell is introduced, which can flexibly analyze the offset change of the center of the core relative to the center of the shell by means of the change in concentricity, timely understand the situation of the electrolyte infiltrating the cylindrical battery cell, and achieve the purpose of non-destructive detection of the wettability of the cylindrical core. It also helps to effectively grasp the infiltration time of the cylindrical battery cell. The method for obtaining the wetting condition of a battery cell provided in an embodiment of the present application can be applied to various scenarios such as quality control scenarios, battery performance optimization scenarios, battery safety assessment scenarios, battery research and development scenarios, and battery status prediction scenarios in the battery manufacturing process, and the embodiment of the present application is not limited to this.

[0041] It should be noted that the information (including but not limited to user device information, user personal information, etc.), data (including but not limited to data used for analysis, stored data, displayed data, etc.) and signals involved in this application are all authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant laws, regulations and standards in the relevant regions. For example, the cylindrical battery cells, wetted cross sections and other contents involved in this application are all obtained with full authorization.

[0042] Secondly, the situation acquisition system involved in the embodiment of the present application is described. The method for acquiring the cell wetness situation provided in the embodiment of the present application can be implemented by the terminal alone, or by the terminal and the server through data interaction (such as the server is responsible for processing the data sent by the terminal), which is not limited in the embodiment of the present application. Optionally, the method for acquiring the cell wetness situation executed by the terminal is described as an example.

[0043] For illustration, please refer to Figure 1 The cylindrical battery cell is analyzed by the terminal 110 in the situation acquisition system. The cylindrical battery cell includes a winding core and a metal shell. The metal shell is used to wrap the winding core. The outer diameter of the winding core is smaller than the inner diameter of the metal shell.

[0044] In some embodiments, the terminal 110 in the situation acquisition environment collects a first wetting cross-section corresponding to the end of the cylindrical battery cell during the electrolyte infiltration process; and collects a second wetting cross-section corresponding to the middle of the cylindrical battery cell during the electrolyte infiltration process.

[0045] Schematically, the cell end is one end of the cylindrical cell, such as the end of the positive electrode of the cell or the end of the negative electrode of the cell; the cell middle is an area determined based on the center of the cylindrical cell. During the process of the cylindrical cell being infiltrated by the electrolyte, a first infiltration cross section is obtained from the cell end, and a second infiltration cross section is obtained from the cell middle. The infiltration cross section characterizes the changes of the cylindrical cell during the electrolyte infiltration process, including the expansion of the core.

[0046] In some embodiments, the terminal 110 obtains a first concentricity corresponding to an end of the battery cell based on the first wetted cross section, and obtains a second concentricity corresponding to a middle of the battery cell based on the second wetted cross section.

[0047] The concentricity is used to characterize the degree of deviation of the center of the core relative to the center of the shell in the wetted cross section. Schematically, the first concentricity is obtained by analyzing the degree of deviation of the center of the core relative to the center of the shell for the first wetted cross section, and the second concentricity is obtained by analyzing the degree of deviation of the center of the core relative to the center of the shell for the second wetted cross section.

[0048] In some embodiments, the terminal 110 displays the wetting condition of the cylindrical battery cell based on the difference between the first concentricity and the second concentricity.

[0049] Among them, the wetting condition is used to characterize the degree of electrolyte infiltration of the cylindrical battery cell. Schematically, the difference between the first concentricity and the second concentricity characterizes the difference in the degree of infiltration between the end and the middle of the core during the electrolyte infiltration process. If the difference between the first concentricity and the second concentricity is smaller, it means that the difference in the degree of infiltration between the end and the middle of the core is smaller, and the infiltration is more uniform; if the difference between the first concentricity and the second concentricity is larger, it means that the difference in the degree of infiltration between the end and the middle of the core is larger, and the infiltration is more uneven, etc.

[0050] It is worth noting that the above-mentioned terminals include but are not limited to mobile terminals such as mobile phones, tablet computers, portable laptops, intelligent voice interaction devices, smart home appliances, etc., and can also be implemented as desktop computers, etc.; the above-mentioned servers can be independent physical servers, or they can be server clusters or distributed systems composed of multiple physical servers, or they can also be cloud servers.

[0051] In combination with the above-mentioned noun introduction and application scenarios, the method for obtaining the cell wetting condition provided in the present application is described, and the method is applied to a terminal as an example. Figure 2 As shown, the method includes the following steps 210 to 230.

[0052] Step 210, collecting a first wetting cross section corresponding to the end of the cylindrical battery cell during the electrolyte infiltration process; and collecting a second wetting cross section corresponding to the middle of the cylindrical battery cell during the electrolyte infiltration process.

[0053] Among them, the cylindrical battery cell includes a winding core and a metal shell. The metal shell is used to wrap the winding core, and the outer diameter of the winding core is smaller than the inner diameter of the metal shell.

[0054] Schematically, a cylindrical cell generally refers to a battery cell having a cylindrical shape, and a cylindrical cell is a chemical battery; in the preparation process of the cylindrical cell, the positive electrode sheet, the negative electrode sheet, the separator and other materials are usually wound into a core in a certain order and tension, and then the core is wrapped with a metal shell to protect the core.

[0055] Schematically, the positive and negative electrode sheets are cut to appropriate sizes according to the design requirements, and the length, width and thickness of the sheets (positive and negative electrodes) need to be precisely controlled; when preparing the core through the winder, the winding parameters are set on the winder, including winding tension, winding speed, alignment of the electrode sheets and diaphragms, etc.; during the winding process, the winder winds the positive electrode sheets, negative electrode sheets and diaphragms into a core according to the set parameters. Usually, the negative electrode sheet will wrap the positive electrode sheet, and the diaphragm will act as an isolation. The tension should be controlled during the winding process to ensure the density and structural stability of the core; then the core is placed in a metal shell, which is usually a steel shell, an aluminum shell, etc.

[0056] In order to realize the electrochemical reaction inside the cylindrical battery cell, the electrolyte is injected into the cylindrical battery cell so that the electrolyte infiltrates the cylindrical battery cell. For example, the electrolyte is injected into the cylindrical battery cell under the condition of controlling the moisture and environmental conditions.

[0057] The electrolyte is the medium for ion transmission in lithium-ion batteries. During the battery charging and discharging process, lithium ions need to migrate between the positive and negative electrodes through the electrolyte. Without the electrolyte, the electrochemical reaction cannot be achieved inside the battery, and the battery cannot work properly. In addition, the electrolyte can also improve the ionic conductivity inside the battery, reduce the internal resistance of the battery, and improve the charging and discharging efficiency of the battery. Therefore, soaking the cylindrical battery cell with the electrolyte is an important step in preparing the cylindrical battery cell for subsequent application.

[0058] Optionally, the electrolyte generally mainly includes a lithium salt and an organic solvent.

[0059] Lithium salt is the source of conductive ions in the electrolyte, accounting for 10% to 12% of the total mass of the electrolyte. Lithium salt can release lithium ions after dissolving in a solvent, thereby improving the conductivity of the electrolyte. The most commonly used lithium salt is lithium hexafluorophosphate (LiPF6), which has good conductivity and relatively stable chemical properties. In addition, lithium salts such as lithium bis(fluorosulfonyl)imide (LiFSI) are also widely used.

[0060] Organic solvents are the most important component of electrolytes, usually accounting for 80% to 85% of the total mass of the electrolyte. Organic solvents provide a dissolving environment for lithium salts and serve as carriers for transporting lithium ions. Commonly used organic solvents include carbonate solvents, such as ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), etc. Organic solvents can be used alone, but it is more common to mix different organic solvents in a certain proportion to obtain better comprehensive performance. For example, EC is usually mixed with DMC or EMC to improve the conductivity and stability of the electrolyte.

[0061] In addition, the electrolyte may also include additives at a lower content, usually accounting for 3% to 5% of the total mass, but they have a significant effect on battery performance. Additives can improve the electrochemical stability of the electrolyte, increase the cycle life of the battery, enhance the safety performance of the battery, etc. Common additives include film-forming additives (such as vinylene carbonate VC and fluoroethylene carbonate FEC), overcharge protection additives, high / low temperature performance improvement additives, flame retardant additives, etc.

[0062] Optionally, the process of electrolyte infiltration into the cylindrical battery cell is usually slow, and the infiltration time is usually affected by at least one of multiple influencing factors such as the vacuum environment, the length of the cylindrical battery cell, the physicochemical properties of the electrolyte, the amount of electrolyte used, the material of the diaphragm, etc. The infiltration time usually ranges from a few minutes to a few hours.

[0063] In some embodiments, during the process of the cylindrical battery cell being infiltrated by the electrolyte, a first infiltration cross section is collected from the end of the battery cell, and a second infiltration cross section is collected from the middle of the battery cell.

[0064] Schematically, the wetted cross section represents the cross section collected during the wetted process, and the first wetted cross section and the second wetted cross section are cross sections collected from different parts of the cylindrical battery cell, so the first wetted cross section and the second wetted cross section are different.

[0065] Optionally, in the process of obtaining the cylindrical battery cell through the winding process and the casing process, the positive and negative pole pieces are led out from the cylindrical battery cell using pole ears. The pole ears are metal conductors. The positive pole ears used to lead out the positive pole pieces are usually made of aluminum (Al) material, and the negative pole ears used to lead out the negative pole pieces are made of nickel (Ni) material. After the winding is completed to obtain the core, the pole ears will be welded to the corresponding pole pieces and connected to the outside of the battery cell through the cap, so that the positive and negative poles of the cylindrical battery cell can be clearly distinguished by the position of the pole ears and the welding condition.

[0066] Optionally, the cell end is one end of the cylindrical cell, such as the positive end or negative end of the cylindrical cell; or, the cell end is a partial length including one end of the cylindrical cell, such as the positive end of the cylindrical cell is 1 / 5 of the starting length of the cylindrical cell.

[0067] Schematically, during the process of the cylindrical battery cell being infiltrated by the electrolyte, the selected battery cell end is scanned by the Computed Tomography (CT) technology to obtain a first infiltration cross section. For example: the positive end of the cylindrical battery cell is used as the battery cell end, and the positive end is scanned by the CT technology during the infiltration process to obtain the first infiltration cross section; or, the positive end of the cylindrical battery cell is used as the starting 1 / 5 of the length of the cylindrical battery cell as the battery cell end, and any cross section within 1 / 5 of the length is scanned by the CT technology during the infiltration process to obtain the first infiltration cross section, etc.

[0068] Optionally, the middle of the battery cell is the middle of the cylindrical battery cell, such as the center of the cylindrical battery cell; or, the middle of the battery cell is the partial length including the center of the cylindrical battery cell, such as 1 / 5 of the length of the cylindrical battery cell with the center of the cylindrical battery cell as the midpoint (from the 2 / 5 position of the cylindrical battery cell to the 3 / 5 position of the cylindrical battery cell), etc.

[0069] Schematically, during the process of the cylindrical battery cell being infiltrated by the electrolyte, the middle of the selected battery cell is scanned by CT technology to obtain the second infiltration cross section. For example, the center of the cylindrical battery cell is taken as the middle of the battery cell, and the center of the cylindrical battery cell is scanned by CT technology during the infiltration process to obtain the second infiltration cross section; or, the 2 / 5 position to the 3 / 5 position of the cylindrical battery cell is taken as the middle of the battery cell, and any cross section in this part is scanned by CT technology during the infiltration process to obtain the second infiltration cross section, etc.

[0070] Step 220 , obtaining a first concentricity corresponding to the end of the battery cell based on the first wetted cross section, and obtaining a second concentricity corresponding to the middle of the battery cell based on the second wetted cross section.

[0071] Schematically, the wetted cross section is used to characterize the changes of the cylindrical battery cell during the electrolyte infiltration process, especially the changes of the winding core in the cylindrical battery cell. Optionally, the winding core expands during the electrolyte infiltration process.

[0072] Schematically, when the electrolyte is injected into the cylindrical battery cell and contacts the electrode material (positive electrode material, negative electrode material), physical and chemical reactions occur, which may cause the volume expansion of the electrode material. For example, when the electrolyte first contacts the electrode material, a chemical reaction may occur and a solid electrolyte interface (SEI) may be formed. Gases such as carbon dioxide (CO2) and hydrogen (H2) may be produced in this process, causing the battery cell to expand.

[0073] Among them, the first infiltration cross section is used to characterize the expansion of the core at the end of the battery cell during the electrolyte infiltration process; the second infiltration cross section is used to characterize the expansion of the core at the middle of the battery cell during the electrolyte infiltration process, etc.

[0074] Schematically, considering that the cylindrical battery cell includes an internal winding core and an external metal shell, the infiltration cross-section obtained based on the infiltration process includes not only the hierarchical structure and winding tightness of the internal winding core, but also the positional relationship of the metal shell relative to the winding core.

[0075] Optionally, the positional relationship of the winding core at the end of the battery cell relative to the metal shell is analyzed based on the first wetted cross section to obtain a first concentricity at the end of the battery cell; in addition, the positional relationship of the winding core at the middle of the battery cell relative to the metal shell is analyzed based on the second wetted cross section to obtain a second concentricity at the middle of the battery cell, etc.

[0076] Among them, concentricity is used to characterize the degree of deviation of the center of the core relative to the center of the shell in the wetted cross section.

[0077] Schematically, the first wetted cross section is used to characterize the degree of deviation of the core center of the winding core at the end of the battery cell relative to the shell center of the metal shell. For example, the core center of the winding core is determined based on the first wetted cross section, and the shell center of the metal shell is determined, so as to analyze the degree of deviation of the core center relative to the shell center with reference to the shell center, and obtain the first concentricity corresponding to the battery cell end.

[0078] Schematically, the second wetted cross section is used to characterize the degree of deviation of the core center of the winding core at the middle of the battery cell relative to the shell center of the metal shell. For example, the core center of the winding core is determined based on the second wetted cross section, and the shell center of the metal shell is determined, so as to analyze the degree of deviation of the core center relative to the shell center with the shell center as a reference, and obtain the second concentricity corresponding to the middle of the battery cell.

[0079] Step 230: Display the wetting condition of the cylindrical battery cell based on the difference between the first concentricity and the second concentricity.

[0080] Schematically, in the process of infiltrating the cylindrical battery cell with electrolyte, the electrolyte is first injected into the cylindrical battery cell, and the injection process usually takes a few seconds to several minutes; the electrolyte is usually injected through the injection port of the cylindrical battery cell, and the injection port is usually located at the top or side of the cylindrical battery cell.

[0081] Optionally, the liquid injection method can be a normal pressure liquid injection method or a vacuum liquid injection method.

[0082] The normal pressure injection method usually carries out the injection process under atmospheric pressure (0-1 atmospheres), and usually relies on the fluidity of the electrolyte itself and the water absorption of the internal structure of the battery cell to achieve the infiltration process, rather than relying on external high pressure differences. The normal pressure injection method may take a long time to ensure the uniform distribution of the electrolyte, but it helps to reduce the mechanical stress of the cylindrical battery cell during the injection process, thereby possibly improving the long-term stability and life of the cylindrical battery cell.

[0083] The vacuum injection method is to perform the injection process under a vacuum environment. Usually, a vacuum pump is used to evacuate the interior of the cylindrical battery cell before injection to reduce the pressure inside the cylindrical battery cell, so that the electrolyte can be more easily injected and infiltrated into the cylindrical battery cell. The pressure of the vacuum injection is usually negative pressure, that is, a pressure value lower than the atmospheric pressure. For example, the vacuum pressure during injection is generally maintained above -98kPa. In the vacuum injection method, since the interior of the cylindrical battery cell is in a negative pressure state, the electrolyte injected from the injection port will be more easily sucked into the interior of the cylindrical battery cell.

[0084] After the electrolyte is injected into the cylindrical battery cell through the injection port, the electrolyte will begin to penetrate along the pores of the electrode plates and the diaphragm to achieve the infiltration process. During this infiltration process, the electrolyte is mainly distributed on the upper part and edge of the cylindrical battery cell, and gradually penetrates into the inside. Therefore, the electrolyte gradually diffuses from the end of the cylindrical battery cell to the middle of the battery cell. Therefore, the cylindrical battery cell usually needs to be left to stand for a period of time after the electrolyte is injected to allow the electrolyte to fully infiltrate the electrode plates, diaphragms, etc. inside the cylindrical battery cell. In addition, in order to improve the infiltration efficiency, the cylindrical battery cell can also be pressurized during the infiltration process to promote the distribution of the electrolyte inside the cylindrical battery cell.

[0085] Optionally, considering the gradual wetting process, the wetting degree of the battery cell ends and the middle of the battery cell may not be uniform. Therefore, after obtaining the first concentricity corresponding to the battery cell ends and the second concentricity corresponding to the middle of the battery cell, the wetting conditions of the electrolyte at the battery cell ends and the middle of the battery cell can be compared by comparing the first concentricity and the second concentricity to analyze whether the electrolyte infiltration is uniform.

[0086] Schematically, the main function of the metal shell is to provide mechanical protection and structural stability. The interaction between the electrolyte and the metal shell is usually limited. After being infiltrated by the electrolyte, the metal shell generally does not undergo significant expansion changes. Therefore, the center of the steel shell in the first infiltration cross section and the second infiltration cross section usually does not change. The comparison between the first concentricity and the second concentricity focuses more on expressing the position comparison relationship between the center of the core at the end of the battery cell and the middle of the battery cell. For example, the first concentricity indicates that the center of the core is more deviated from the center of the shell, and the second concentricity indicates that the center of the core is closer to the center of the shell. The first concentricity and the second concentricity indicate that the degree of deviation of the center of the core from the center of the shell is not the same.

[0087] In some embodiments, the terminal is connected to a CT device, which obtains a first infiltration cross-section and a second infiltration cross-section, and sends the first infiltration cross-section and the second infiltration cross-section to the terminal for analysis. The terminal determines a first concentricity based on the first infiltration cross-section, and determines a second concentricity based on the second infiltration cross-section. The terminal then compares the difference between the first concentricity and the second concentricity, and displays the infiltration condition of the cylindrical battery cell on a screen of the terminal.

[0088] The infiltration condition is used to characterize the degree of electrolyte infiltration into the cylindrical battery cell. Displaying the infiltration condition on the screen of the terminal helps inform the cylindrical battery cell preparation personnel of the current electrolyte infiltration progress.

[0089] Optionally, if the difference between the first concentricity and the second concentricity is larger, it means that the wetting of the cylindrical battery cell is more uneven, and the terminal displays the first wetting condition to indicate that the current wetting uniformity of the cylindrical battery cell is poor, and it will take a longer time to wetting the cylindrical battery cell; if the difference between the first concentricity and the second concentricity is smaller, it means that the wetting of the cylindrical battery cell is more uniform, and the terminal displays the second wetting condition to indicate that the current wetting uniformity of the cylindrical battery cell is better, and it will take less time to wetting the cylindrical battery cell or the wetting of the cylindrical battery cell is completed, etc.

[0090] Schematically, the battery cell is the basic component for building a battery. A battery is usually composed of one or more battery cells, which can be cylindrical battery cells or battery cells of other shapes. Therefore, the more uniformly the cylindrical battery cell is infiltrated with the electrolyte, the more helpful it is to improve the battery performance of the battery built based on the cylindrical battery cell.

[0091] Taking the construction of batteries with cylindrical cells as an example, the more uniform the infiltration of the cylindrical cells, the better the battery performance will be: (1) improving the charge and discharge performance of the battery, such as uniform infiltration helps ensure that the electrolyte is in full contact with the electrode material, thereby improving the transmission efficiency of lithium ions and improving the charge and discharge performance of the battery; (2) extending the cycle life of the battery, such as good infiltration can ensure the uniformity of the electrochemical reaction during the charge and discharge process of the battery, reduce local overcharge or overdischarge of the electrode material, and thus extend the service life of the battery; (3) reducing the internal resistance of the battery, such as because the electrolyte is a medium for ion transmission, uneven infiltration may lead to uneven current distribution and increase the internal resistance of the battery; (4) reducing side reactions during battery use, such as uniform contact between the electrolyte and the electrode material can reduce the excessive concentration or dilution of the electrolyte in local areas, thereby reducing the occurrence of side reactions such as electrolyte decomposition or corrosion of the electrode material.

[0092] It is worth noting that the above are merely illustrative examples and are not limited to the embodiments of the present application.

[0093] In summary, the change in concentricity can be used to flexibly analyze the offset change of the core center relative to the shell center, so as to flexibly determine the degree of electrolyte infiltration of the cylindrical battery cell. This helps to understand the situation of electrolyte infiltration of the cylindrical battery cell more timely, achieve the purpose of non-destructive testing of the wettability of the cylindrical core, avoid the problem of needing to destroy the cylindrical battery cell to analyze the degree of infiltration, and also helps to effectively grasp the infiltration time of the cylindrical battery cell and improve the processing efficiency of the cylindrical battery cell infiltration process.

[0094] In an optional embodiment, the distance from the center of the winding core to the center of the housing is used as the concentricity, so as to analyze the wetting condition of the cylindrical battery cell based on the difference between the first concentricity and the second concentricity. Figure 3 As shown above Figure 2 The illustrated embodiment may also be implemented as steps 310 to 330 as follows; wherein step 220 may also be implemented as steps 321 to 322 and steps 323 to 324 as follows.

[0095] Step 310, collecting a first wetting cross section corresponding to the end of the cylindrical battery cell during the electrolyte infiltration process; and collecting a second wetting cross section corresponding to the middle of the cylindrical battery cell during the electrolyte infiltration process.

[0096] Schematically, when the cylindrical battery cell is infiltrated by the electrolyte, the cylindrical battery cell is scanned using CT technology, and the infiltration cross-sections of the cylindrical battery cell at different positions are obtained by setting different scanning depths.

[0097] CT technology is a non-destructive detection method. It uses X-rays to penetrate cylindrical cells and the detector receives the transmitted X-rays. Then, a detailed image of the internal structure of the cylindrical cell is generated through computer processing. The scanning depth usually indicates the depth and position that the X-rays can penetrate the cylindrical cell. By setting different scanning depths, the infiltration cross-section acquisition process can be performed for different parts of the cylindrical cell. In the infiltration cross-section obtained by CT technology scanning, the winding structure of the core in the cylindrical cell, the arrangement of the electrode plates and diaphragms, and the distribution of the electrolyte are clearly displayed.

[0098] Schematically, the positive end of the cylindrical battery cell is used as the scanning starting point, a smaller scanning depth is set to obtain the first wetted cross section corresponding to the end of the battery cell, and a larger scanning depth is set to obtain the second wetted cross section corresponding to the middle of the battery cell. For example: the length of the cylindrical battery cell is 65 mm, the scanning depth is set to 10 mm (located within 1 / 5 of the length), and the first wetted cross section is obtained; the scanning depth is set to 30 mm (located within 2 / 5 of the length value 3 / 5) to obtain the second wetted cross section, etc. This is only an illustrative example, and the embodiments of the present application are not limited to this.

[0099] Among them, the cylindrical battery cell includes a winding core and a metal shell. The metal shell is used to wrap the winding core, and the outer diameter of the winding core is smaller than the inner diameter of the metal shell.

[0100] Schematically, the metal shell is a steel shell, an aluminum shell, etc.; the outer diameter of the core is the radius / diameter of the area enclosed by the outermost layer of the core, and the inner diameter of the metal shell is the radius / diameter of the area enclosed by the innermost layer of the metal shell, etc.; since the metal shell is used to wrap the core, the inner diameter of the metal shell should be smaller than the outer diameter of the core.

[0101] Indicatively, the model of a cylindrical battery cell is usually determined by the length of the cylindrical battery cell. For example, a cylindrical battery cell of model 18650 represents a diameter of 18 mm and a length of 65 mm. The metal shell of a cylindrical battery cell of model 18650 is usually a steel shell. In addition, there are cylindrical batteries of model 21700 and model 26650, etc. The model of the cylindrical battery cell to be analyzed is not limited here.

[0102] In an optional embodiment, the electrolyte infiltrates from at least one end of the cylindrical battery cell toward the middle of the battery cell.

[0103] Among them, the cylindrical battery cell includes a positive terminal and a negative terminal. Schematically, the electrolyte is injected from both ends of the cylindrical battery cell (the injection port near the positive terminal and the injection port near the negative terminal), and the electrolyte infiltrates from both ends of the roll core to the middle of the roll core during the infiltration process to achieve the infiltration process; or, the electrolyte is injected from one end of the cylindrical battery cell (the injection port near the positive terminal or the injection port near the negative terminal), and the electrolyte diffuses from one end of the injected electrolyte to the other end during the infiltration process.

[0104] Step 321 : determining a first winding core region corresponding to the winding core and a first shell region corresponding to the metal shell from the first wetted cross section.

[0105] Schematically, the wetted cross section represents the cross section collected during the infiltration process, which is used to characterize the changes of the cylindrical battery cell during the electrolyte infiltration process, especially the changes of the winding core inside the cylindrical battery cell; the wetted cross section includes the winding core and the metal shell. If the metal shell does not change with the electrolyte, the changes of the winding core with the infiltration of the electrolyte can be observed through the wetted cross section, and the changes in the position of the winding core relative to the metal shell with the injection of the electrolyte can also be observed.

[0106] Schematically, the first wetted cross-section includes a cross-sectional area corresponding to the core, which is called the first core area, and also includes a cross-sectional area corresponding to the metal shell, which is called the first shell area; since the core is wrapped in the metal shell, the first core area and the first shell area overlap with each other, and the first shell area includes the first core area.

[0107] Step 322 , taking a first distance by which the center of the winding core in the first winding core region is offset from the center of the outer shell in the first outer shell region as a first concentricity corresponding to the end of the battery cell.

[0108] Among them, concentricity is used to characterize the degree of deviation of the center of the core relative to the center of the shell in the wetted cross section.

[0109] Schematically, the center of the core is determined from within the first core area, and the center of the shell is determined from within the first shell area. With the shell center as a reference, the offset distance of the core center relative to the shell center is analyzed to obtain a first distance, and the first distance is used as the first concentricity corresponding to the end of the battery cell.

[0110] For example: during the process of the core absorbing electrolyte and causing expansion, the core area in the wetted cross section may change, so the position of the core center may also change relatively; if the metal shell is not affected by the electrolyte, the first shell area remains unchanged during the electrolyte infiltration process, and the shell center also remains unchanged, then the first distance of the core center relative to the shell center may change, etc. If the shell center is used as a reference, the first distance of the core center from the shell center is analyzed to be 0.05 mm, then 0.05 mm can be used as the first concentricity. In addition, the first distance and deviation direction can be combined to obtain the first concentricity, such as taking the shell center as a reference, the core center is offset by 0.05 mm from the shell center at 30 degrees in the northeast direction, etc., which is not limited here.

[0111] In an optional embodiment, the geometric center of the region is determined from the first core region as the core center, and the geometric center of the region is determined from the first shell region as the shell center; and the first distance by which the core center is offset relative to the shell center is used as the first concentricity corresponding to the end of the battery cell.

[0112] Schematically, when determining the core center and the shell center from the core area and the shell area respectively, the regional geometric center is determined from the first core area as the core center, and the regional geometric center is determined from the first shell area as the shell center.

[0113] The geometric center of a region is also called the center of mass or centroid. It refers to the point of gravity of all the mass points of an object or region. In two-dimensional space, such as an infiltration cross section, the geometric center of a region refers to the average position of all the points in the region, that is, the average value of the coordinates of all the points (such as x-coordinates and y-coordinates).

[0114] Afterwards, after the core center and the shell center are determined based on the regional geometric center as a standard, a first distance of the core center offset relative to the shell center in the first wetted cross section is analyzed and used as a first concentricity.

[0115] Step 323 : determining a second winding core region corresponding to the winding core and a second shell region corresponding to the metal shell from the second wetted cross section.

[0116] Schematically, the cross-sectional area corresponding to the core included in the second wetted cross-section is called the second core area, and the cross-sectional area corresponding to the metal shell is called the second shell area; since the core is wrapped in the metal shell, the second core area and the second shell area overlap with each other, and the second shell area includes the second core area.

[0117] Step 324 , taking a second distance by which the center of the winding core in the second winding core region is offset from the center of the outer shell in the second outer shell region as a second concentricity corresponding to the middle of the battery cell.

[0118] Schematically, the center of the core is determined from the second core area, and the center of the shell is determined from the second shell area. With the shell center as a reference, the offset distance of the core center relative to the shell center is analyzed to obtain the second distance, and the second distance is used as the second concentricity corresponding to the end of the battery cell.

[0119] For example: during the process of the core absorbing electrolyte and causing expansion, the core area in the wetted cross section may change, so the position of the core center may also change relatively; if the metal shell is not affected by the electrolyte, the second shell area remains unchanged during the electrolyte infiltration process, and the shell center also remains unchanged, then the second distance of the core center relative to the shell center may change, etc. If the shell center is used as a reference, the second distance of the core center from the shell center is analyzed to be 0.02 mm, then 0.02 mm can be used as the second concentricity. In addition, the second concentricity can be obtained by combining the second distance and the deviation direction, such as taking the shell center as a reference, the core center is offset by 0.02 mm from the shell center at 20 degrees in the southeast direction, etc., which is not limited here.

[0120] In an optional embodiment, the regional geometric center is determined from the second core region as the core center, and the regional geometric center is determined from the second shell region as the shell center; the second distance by which the core center is offset relative to the shell center is used as the second concentricity corresponding to the middle of the battery cell.

[0121] Illustratively, when the core center and the shell center are determined from the core area and the shell area respectively, the regional geometric center is determined from the second core area as the core center, and the regional geometric center is determined from the second shell area as the shell center.

[0122] Afterwards, after the core center and the shell center are determined based on the regional geometric center, a second distance of the core center offset relative to the shell center in the second wetting cross section is analyzed and used as the second concentricity.

[0123] It is worth noting that the above are merely illustrative examples and are not limited to the embodiments of the present application.

[0124] Step 330: Display the wetting condition of the cylindrical battery cell based on the difference between the first concentricity and the second concentricity.

[0125] Among them, the wetting condition is used to characterize the degree to which the electrolyte infiltrates the cylindrical battery cell.

[0126] Indicatively, after obtaining the first concentricity and the second concentricity, the difference between the first concentricity and the second concentricity is compared to analyze the difference between the wetting degree of the battery end and the wetting degree of the middle of the battery, such as the wetting degree of the battery end is larger and the wetting degree of the middle of the battery is smaller; or, the wetting degree of the battery end is the same as the wetting degree of the middle of the battery, etc.

[0127] Optionally, if the difference between the first concentricity and the second concentricity is greater, it means that the wetting of the cylindrical cell is more uneven, and the terminal displays the first wetting condition to prompt that the current wetting uniformity of the cylindrical cell is poor and it will take longer to wetting the cylindrical cell. For example: the first wetting condition is in text form, expressed as "the current wetting is not uniform"; or the first wetting condition is in image form, expressed as a first image of a combination of a first wetting cross section and a first concentricity (such as a first wetting cross section marked with the first concentricity), and a second image of a combination of a second wetting cross section and a second concentricity, etc.

[0128] Optionally, if the difference between the first concentricity and the second concentricity is smaller, it means that the cylindrical cell is more uniformly wetted, and the terminal displays the second wetness condition to indicate that the current wetness uniformity of the cylindrical cell is good, and that less time is needed to wet the cylindrical cell or that the wetness of the cylindrical cell is complete, etc. For example, the second wetness condition is in text form, showing "the wetness is currently uniform, and the wetness process can be stopped"; or the second wetness condition is in image form, showing the overlap of the first image and the second image, etc.

[0129] Schematically, cylindrical cells can be used as basic components for building batteries. If the cylindrical cells are more evenly infiltrated with electrolyte, the more it helps to improve the battery performance of the battery built based on the cylindrical cells.

[0130] It is worth noting that the above are merely illustrative examples and are not limited to the embodiments of the present application.

[0131] In summary, the change in concentricity can be used to flexibly analyze the offset change of the core center relative to the shell center, so as to flexibly determine the degree of electrolyte infiltration of the cylindrical battery cell, such as incomplete infiltration or complete infiltration. This helps to understand the situation of electrolyte infiltration of the cylindrical battery cell more timely, achieve the purpose of non-destructive testing of the wettability of the cylindrical core, avoid the problem of destroying the cylindrical battery cell to analyze the degree of infiltration, and also help to effectively grasp the infiltration time of the cylindrical battery cell and improve the processing efficiency of the cylindrical battery cell infiltration process.

[0132] In the embodiments of the present application, the content of using the deviation distance of the center of the core relative to the center of the shell as the concentricity is introduced. By analyzing the wetting cross-section obtained by scanning different parts of the battery cell, the concentricity result is used to determine the uniformity of the cylindrical cell being wetting with the electrolyte, so as to display the wetting condition of the cylindrical cell on the terminal interface in a targeted manner, and quantify the uniformity of the wetting. There is no need to disassemble the cylindrical cell and waste time, so the purpose of online control can be achieved more efficiently.

[0133] In an optional embodiment, the cell ends and the cell middle are selected based on a preset cell length, so as to obtain a first wetted cross section based on the cell ends and a second wetted cross section based on the cell middle. Figure 4 As shown above Figure 2 The illustrated step 210 may also be implemented as the following steps 410 to 430 .

[0134] Step 410 , taking the positive electrode of the cylindrical battery cell as the starting point, selecting a first preset battery cell length from the cylindrical battery cell as the battery cell end.

[0135] Illustratively, a first preset cell length is pre-set, and the first preset cell length can be a preset length value, such as 10 mm, or a length determined by combining the cylindrical cell length with a preset ratio, such as 1 / 5 of 65 mm, which is not limited here.

[0136] Optionally, taking the positive electrode of the cylindrical battery cell as the starting point, a first preset battery cell length is selected to obtain the battery cell end of the cylindrical battery cell, that is, the battery cell end is a partial cylindrical battery cell.

[0137] Step 420 , taking the center point of the cylindrical battery cell as the center, select a second preset battery cell length from the cylindrical battery cell as the middle of the battery cell.

[0138] Illustratively, a second preset cell length is pre-set, and the second preset cell length can be either a preset length value or a length determined by combining the cylindrical cell length with a preset ratio; in addition, when the second preset cell length is implemented as a length value, it can be the same as the first preset cell length or different from the first preset cell length, which is not limited here.

[0139] Optionally, the center point of the cylindrical battery cell is determined, and a second preset battery cell length is selected with the center point as the center to obtain the middle of the cylindrical battery cell; or, the second preset battery cell length is selected with the center point as the starting point to obtain the middle of the cylindrical battery cell; or, the second preset battery cell length is selected with the center point as the end point to obtain the middle of the cylindrical battery cell, etc.; that is, the middle of the battery cell is a partial cylindrical battery cell.

[0140] The cell ends and the cell middle are independent of each other. Schematically, since the subsequent wetting analysis process needs to be performed based on the cell ends and the cell middle, the cell ends and the cell middle are two independent parts that do not intersect on the cylindrical cell.

[0141] Step 430 , during the process of the cylindrical battery cell being infiltrated by the electrolyte, a circular cross section is collected from the end of the battery cell as a first infiltration cross section, and a circular cross section is collected from the middle area of ​​the battery cell as a second infiltration cross section.

[0142] Optionally, a tomographic scan is performed on a cross section selected from the cylindrical battery cell at a first scanning depth to obtain a first wetting cross section corresponding to an end of the battery cell.

[0143] Among them, the first scanning depth is a scanning depth that conforms to the interval where the end of the battery cell is located. Schematically, the cross section at the first scanning depth is scanned by CT technology to obtain a first wetting cross section. Schematically, in the process of the cylindrical battery cell being infiltrated by the electrolyte, a scanning process is performed based on the first scanning depth to select any cross section from the end of the battery cell to obtain a first wetting cross section. Schematically, any cross section within the end of the battery cell is scanned by CT technology to obtain a first wetting cross section. If the end of the battery cell is a 0-1 / 5 length portion, the scanning depth is limited to the 0-1 / 5 length portion for the scanning process, thereby obtaining a first wetting cross section.

[0144] Optionally, a tomographic scan is performed on the cylindrical battery cell at a second scanning depth to obtain a second wetting cross section corresponding to the middle of the battery cell.

[0145] Among them, the second scanning depth is a scanning depth that conforms to the interval where the middle of the battery cell is located. The cross-section at the second scanning depth is scanned by CT technology to obtain a second wetting cross-section. Schematically, in the process of the cylindrical battery cell being infiltrated with electrolyte, a scanning process is performed based on the second scanning depth, and any cross-section is selected from the middle of the battery cell to obtain a second wetting cross-section. Schematically, any cross-section in the middle of the battery cell is scanned by CT technology to obtain a second wetting cross-section. If the middle of the battery cell is a 2 / 5-3 / 5 length portion, the scanning depth is limited to the 2 / 5-3 / 5 length portion for the scanning process, thereby obtaining a second wetting cross-section.

[0146] It is worth noting that the above are merely illustrative examples and are not limited to the embodiments of the present application.

[0147] In summary, the change in concentricity can be used to flexibly analyze the offset change of the core center relative to the shell center, so as to flexibly determine the degree of electrolyte infiltration of the cylindrical battery cell, such as incomplete infiltration or complete infiltration. This helps to understand the situation of electrolyte infiltration of the cylindrical battery cell more timely, achieve the purpose of non-destructive testing of the wettability of the cylindrical core, avoid the problem of destroying the cylindrical battery cell to analyze the degree of infiltration, and also help to effectively grasp the infiltration time of the cylindrical battery cell and improve the processing efficiency of the cylindrical battery cell infiltration process.

[0148] In the embodiment of the present application, the process of selecting the cell end and the middle of the cell by selecting the preset cell length is introduced, and the content of obtaining the first infiltration cross section and the second infiltration cross section by setting the scanning depth is also introduced. This process sets the selection rules for the cell end and the middle of the cell, and can perform more targeted analysis on the cylindrical cell through CT technology and scanning depths that meet the preset cell end and the middle of the cell, and obtain the infiltration cross section more targetedly on the basis of avoiding damage to the cylindrical cell, which is helpful for the subsequent concentricity analysis process.

[0149] In an optional embodiment, different infiltration conditions are displayed based on the difference between the first concentricity and the second concentricity. Figure 5 As shown above Figure 2 The illustrated step 230 may also be implemented as the following step 510 or step 520 .

[0150] Step 510 , when the difference between the first concentricity and the second concentricity is less than a preset threshold, it is displayed that the cylindrical battery cell is in a first wetting state.

[0151] In schematic form, the first concentricity is used as the concentricity corresponding to the end of the battery cell, and is used to characterize the degree of offset of the center of the core at the end of the battery cell relative to the center of the outer shell. The second concentricity is used as the concentricity corresponding to the middle of the battery cell, and is used to characterize the degree of offset of the center of the core at the middle of the battery cell relative to the center of the outer shell. When the center of the outer shell remains unchanged, if the difference between the first concentricity and the second concentricity is smaller, it means that the offset of the center of the core at the end of the battery cell and the middle of the battery cell is smaller, which means that the electrolyte infiltration is more uniform.

[0152] Optionally, the preset threshold is a preset value, such as the preset threshold is 0, or the preset threshold is a smaller value such as 0.01 mm.

[0153] Optionally, when the first concentricity and the second concentricity are the same, the cylindrical battery cell is shown to be in a first wetting state.

[0154] In schematic form, if the first concentricity and the second concentricity are the same, it means that the degree of displacement of the center of the core at the end of the cell and the middle of the cell is the same, which means that the expansion of the core at the middle of the cell and the end of the cell is the same, and it also represents that the core is more evenly infiltrated with the electrolyte. At this time, the cylindrical cell is regarded as being in the first wetting condition, and the first wetting condition is displayed on the terminal.

[0155] Among them, the first wetting condition indicates that the degree of wetting of the cylindrical battery cell by the electrolyte meets the wetting requirements.

[0156] Schematically, the wetting condition represents the degree to which the electrolyte infiltrates the cylindrical battery cell. If the difference between the first concentricity and the second concentricity is smaller, it means that the difference in the wetting degree between the end of the core and the middle of the core is smaller, and the wetting is more uniform; if the difference between the first concentricity and the second concentricity is larger, it means that the difference in the wetting degree between the end of the core and the middle of the core is larger, and the wetting is more uneven, etc.

[0157] Optionally, the wetting requirement is a pre-set requirement, such as the wetting requirement indicating that the electrolyte completely soaks the cylindrical battery cell; or the wetting requirement indicating that the electrolyte has substantially soaked the cylindrical battery cell, etc.

[0158] Indicatively, if the first concentricity and the second concentricity are the same, it means that the electrolyte infiltrates the cylindrical battery cell very uniformly or nearly uniformly, so it can be understood that the electrolyte completely infiltrates the cylindrical battery cell, and the degree of electrolyte infiltration into the cylindrical battery cell meets the infiltration requirements.

[0159] Optionally, the first infiltration situation displayed is "the current infiltration is completed", "the infiltration process is completed", "the infiltration degree has reached the application requirements", etc., which is not limited here.

[0160] Step 520 , when the difference between the first concentricity and the second concentricity is not less than a preset threshold, displaying that the cylindrical battery cell is in the second wetting condition.

[0161] In schematic form, when the center of the outer shell remains unchanged, if the difference between the first concentricity and the second concentricity is large, it means that the center of the core is greatly offset at the end of the battery cell and the middle of the battery cell, and the electrolyte infiltration is not uniform at this time; if the difference between the first concentricity and the second concentricity is compared with the preset threshold, if the difference is greater than or equal to the preset threshold, it means that the electrolyte infiltration is not uniform.

[0162] In schematic form, if the preset threshold is 0, then while the center of the outer shell remains unchanged, if the first concentricity and the second concentricity are different, it means that the degree of offset of the center of the core at the end of the cell and the middle of the cell is different. Therefore, the expansion of the core at the middle of the cell and the end of the cell is not the same, which also indicates that the core has not been evenly infiltrated by the electrolyte. At this time, the cylindrical cell is regarded as being in the second wetting condition, and the second wetting condition is displayed on the terminal.

[0163] Among them, the second wetting condition indicates that the degree of wetting of the cylindrical battery cell by the electrolyte does not meet the wetting requirements.

[0164] Indicatively, the displayed wetting requirements are preset requirements, such as the wetting requirement is complete wetting, or the wetting degree reaches 99%, etc. Indicatively, if the difference between the first concentricity and the second concentricity is greater, it means that the difference in the wetting degree between the end of the core and the middle of the core is greater, the wetting is more uneven, etc. If the first concentricity and the second concentricity are different, it means that the electrolyte infiltrates the cylindrical battery cell unevenly at present, so it can be understood that the electrolyte has not yet completely infiltrated the cylindrical battery cell.

[0165] Optionally, the second infiltration status is displayed as "the current infiltration is not yet completed", "the infiltration process needs to be continued", etc., which is not limited here.

[0166] Optionally, considering that the electrolyte usually gradually infiltrates from the end of the battery cell to the middle of the battery cell, the first concentricity is usually greater than the second concentricity.

[0167] Schematically, the process of electrolyte infiltrating a cylindrical battery cell, especially a winding core in the cylindrical battery cell, is described below.

[0168] like Figure 6 As shown, before the electrolyte is injected into the cylindrical battery core, that is, when the cylindrical battery core is not soaked by the electrolyte, there is a small gap between the winding core 610 and the metal shell 620;

[0169] When the electrolyte is injected into the cylindrical battery cell and begins to infiltrate the cylindrical battery cell, the center of the winding core at the end of the battery cell begins to deviate from the center of the shell, and the center of the winding core in the middle of the battery cell has not yet deviated from the center of the shell. At this time, the first concentricity is larger, the second concentricity is 0 or smaller, and the first concentricity is greater than the second concentricity;

[0170] As the wetting process continues, the center of the core at the end of the cell increasingly deviates from the center of the shell, and the center of the core in the middle of the cell also gradually begins to deviate from the center of the shell. At this time, the first concentricity is larger, and the second concentricity gradually increases, but the first concentricity is still greater than the second concentricity.

[0171] As the wetting process continues, the degree of deviation of the center of the core at the end of the cell relative to the center of the shell gradually tends to remain unchanged (the end of the cell is basically completely wetted), and the center of the core in the middle of the cell is still gradually deviating from the center of the shell (the middle of the cell is not completely wetted yet). At this time, the first concentricity remains basically unchanged, and the second concentricity continues to increase, and the first concentricity is still greater than the second concentricity.

[0172] The wetting process continues, and the offset degree of the core center at the end of the battery cell relative to the center of the shell remains unchanged (the end of the battery cell is completely wetted), and the offset degree of the core center at the middle of the battery cell relative to the center of the shell also remains unchanged or relatively unchanged (the middle of the battery cell is also completely wetted). At this time, the first concentricity remains unchanged, and the second concentricity also remains basically unchanged. The first concentricity is slightly larger than the second concentricity or the first concentricity is equal to the second concentricity.

[0173] like Figure 7 As shown, after the electrolyte completely soaks the cylindrical battery cell, the tiny gap between the winding core 710 and the metal shell 720 is filled due to the expansion of the winding core 710.

[0174] It is worth noting that the above are merely illustrative examples and are not limited to the embodiments of the present application.

[0175] In summary, the change in concentricity can be used to flexibly analyze the offset change of the core center relative to the shell center, so as to flexibly determine the degree of electrolyte infiltration of the cylindrical battery cell, such as incomplete infiltration or complete infiltration. This helps to understand the situation of electrolyte infiltration of the cylindrical battery cell more timely, achieve the purpose of non-destructive testing of the wettability of the cylindrical core, avoid the problem of destroying the cylindrical battery cell to analyze the degree of infiltration, and also help to effectively grasp the infiltration time of the cylindrical battery cell and improve the processing efficiency of the cylindrical battery cell infiltration process.

[0176] In an optional embodiment, multiple evaluation moments are selected, and the differences between the first concentricity and the second concentricity at the multiple evaluation moments are analyzed, so as to obtain the corresponding infiltration conditions at the multiple evaluation moments, so as to understand the degree of electrolyte infiltration of the cylindrical battery cell in a more timely manner. Figure 8 As shown above Figure 2 The illustrated embodiment may also be implemented as the following steps 810 to 830 .

[0177] Step 810 , collecting first infiltration cross sections corresponding to the ends of the cylindrical battery cell at multiple evaluation moments during the electrolyte infiltration process; and second infiltration cross sections corresponding to the middle of the battery cell at multiple evaluation moments.

[0178] The cylindrical battery cell includes a winding core and a metal shell. The metal shell is used to wrap the winding core. The outer diameter of the winding core is smaller than the inner diameter of the metal shell.

[0179] Schematically, the evaluation time is a time for evaluating the degree of wetting, and the effect of the electrolyte wetting process on the winding core is analyzed at the evaluation time.

[0180] Optionally, during the process of electrolyte infiltrating the cylindrical battery cell, multiple moments are randomly selected as evaluation moments; or, multiple moments are periodically selected as evaluation moments; or, multiple moments are selected as evaluation moments in a preset regular manner, etc.

[0181] Optionally, during the process of the electrolyte infiltrating the cylindrical battery cell, multiple moments are pre-selected as evaluation moments; or, multiple moments are selected in real time as evaluation moments, such as selecting a certain moment as the evaluation moment as the electrolyte infiltrates the cylindrical battery cell to evaluate the impact of the electrolyte on the core.

[0182] In an optional embodiment, at any one of the multiple evaluation moments, a first wetting cross section corresponding to the end of the battery cell is collected, and a second wetting cross section corresponding to the middle of the battery cell is collected.

[0183] Schematically, at any evaluation moment, the first wetting cross section corresponding to the end of the battery cell is collected by CT technology, and the second wetting cross section corresponding to the middle of the battery cell is collected by CT technology; therefore, the first wetting cross section collected at the current evaluation moment characterizes the degree of electrolyte wetting at the end of the battery cell at the current evaluation moment, and the second wetting cross section collected at the current evaluation moment characterizes the degree of electrolyte wetting in the middle of the battery cell at the current evaluation moment.

[0184] Optionally, a circular cross section is arbitrarily selected from the end of the battery cell as the first wetting cross section corresponding to the current evaluation moment, and a circular cross section is arbitrarily selected from the middle of the battery cell as the second wetting cross section corresponding to the current evaluation moment.

[0185] Schematically, after determining the end and the middle of the battery cell, the corresponding cross-section is selected by setting the scanning depth of the CT technology to obtain the first infiltration cross-section and the second infiltration cross-section; the first infiltration cross-section and the second infiltration cross-section are bound to the selected evaluation moment, thereby reflecting the electrolyte infiltration condition at the evaluation moment.

[0186] In an optional embodiment, the first infiltration cross sections and the second infiltration cross sections corresponding to a plurality of evaluation moments are acquired to obtain a plurality of first infiltration cross sections and a plurality of second infiltration cross sections.

[0187] Schematically, the first wetting cross section and the second wetting cross section collected at each evaluation moment can reflect the degree of infiltration of the electrolyte into the battery cell at the current evaluation moment; when obtaining the first wetting cross section and the second wetting cross section corresponding to multiple evaluation moments, the evaluation moments can be selected one by one in a periodic manner as the infiltration process continues, and the first wetting cross section and the second wetting cross section at each evaluation moment can be obtained.

[0188] Step 820, for a first evaluation moment among the multiple evaluation moments, obtain a first concentricity of a first infiltration cross section acquired at the first evaluation moment, and obtain a second concentricity of a second infiltration cross section acquired at the first evaluation moment.

[0189] Among them, concentricity is used to characterize the degree of deviation of the center of the core relative to the center of the shell in the wetted cross section.

[0190] Schematically, the first wetting cross-section and the second wetting cross-section at each evaluation moment are analyzed respectively to determine the degree of offset of the center of the core at the end of the battery cell relative to the center of the outer shell at any evaluation moment, and obtain the first concentricity at the evaluation moment, and determine the degree of offset of the center of the core at the middle of the battery cell relative to the center of the outer shell at the evaluation moment, and obtain the second concentricity at the evaluation moment.

[0191] Optionally, the first infiltration cross section and the second infiltration cross section at each evaluation moment are analyzed respectively to obtain the first concentricity and the second concentricity corresponding to each evaluation moment.

[0192] Step 830, based on the difference between the first concentricity and the second concentricity corresponding to the multiple evaluation moments, the wetting conditions of the cylindrical battery cell at the multiple evaluation moments are displayed.

[0193] Among them, the wetting condition is used to characterize the degree to which the electrolyte infiltrates the cylindrical battery cell.

[0194] In schematic form, the first concentricity and the second concentricity at the same evaluation time are compared to analyze the wetting conditions corresponding to the cylindrical battery cells at multiple evaluation times.

[0195] Optionally, when multiple evaluation moments are selected in real time, it means that as the electrolyte continues to infiltrate the cylindrical battery cell, the difference between the first concentricity and the second concentricity at the current evaluation moment is analyzed to determine the infiltration condition corresponding to the current moment, and then it can be flexibly determined whether to continue the infiltration process according to the infiltration condition. For example: when the infiltration condition corresponding to the evaluation moment 10 indicates that the electrolyte infiltration is uniform, the infiltration process can be stopped, that is, the electrolyte completes the infiltration of the cylindrical battery cell.

[0196] It is worth noting that the above are merely illustrative examples and are not limited to the embodiments of the present application.

[0197] In summary, the change in concentricity can be used to flexibly analyze the offset change of the core center relative to the shell center, so as to flexibly determine the degree of electrolyte infiltration of the cylindrical battery cell. This helps to understand the situation of electrolyte infiltration of the cylindrical battery cell more timely, achieve the purpose of non-destructive testing of the wettability of the cylindrical core, avoid the problem of needing to destroy the cylindrical battery cell to analyze the degree of infiltration, and also helps to effectively grasp the infiltration time of the cylindrical battery cell and improve the processing efficiency of the cylindrical battery cell infiltration process.

[0198] In the embodiment of the present application, it is introduced to select multiple evaluation moments to analyze the corresponding infiltration conditions of the cylindrical battery cell at multiple evaluation moments. The multiple evaluation moments can be used to quantitatively consider the process of the cylindrical battery cell being infiltrated by the electrolyte, which helps to timely and fully understand the degree of electrolyte infiltration of the cylindrical battery cell, and is more helpful to decide whether to continue the infiltration process and improve the electrolyte infiltration efficiency.

[0199] In an optional embodiment, if multiple evaluation moments are selected and the differences between the first concentricity and the second concentricity are analyzed respectively, multiple first concentricity differences can be obtained, and then the changes of the multiple first concentricity differences can be analyzed to obtain the infiltration curve. Fig. 9 As shown above Figure 2 The illustrated step 230 may then be implemented as the following steps 910 to 920 .

[0200] Step 910, obtaining the difference between the first concentricity and the second concentricity at multiple evaluation moments, and obtaining multiple first concentricity differences.

[0201] There is a one-to-one correspondence between the multiple evaluation moments and the multiple first concentricity differences.

[0202] Indicatively, a difference operation is performed on the first concentricity and the second concentricity at the same evaluation moment to obtain the difference of the first concentricity at the evaluation moment; and the differences of the first concentricity corresponding to multiple evaluation moments are obtained. For example, the larger concentricity is used as the minuend and the smaller concentricity is used as the subtrahend to obtain the difference of the first concentricity.

[0203] For example: the first concentricity at evaluation time 1 is 0.03 mm, and the second concentricity is 0.01 mm, then the difference in the first concentricity corresponding to evaluation time 1 is 0.02 mm, and so on.

[0204] Step 920, analyzing how the differences between the multiple first concentricities change with multiple evaluation moments to obtain a wetting curve.

[0205] Schematically, when multiple first concentricity differences correspond to multiple evaluation moments one by one, the evaluation moment is used as the horizontal axis and the first concentricity difference is used as the vertical axis, so that the infiltration curve is obtained through multiple evaluation moments and multiple first concentricity differences.

[0206] Among them, the wetting curve is used to describe the change pattern of the wetting condition of the cylindrical battery cell with the evaluation time.

[0207] Schematically, the difference between the first concentricity and the second concentricity is described based on the infiltration condition. The difference between the first concentricity and the second concentricity is another expression of the infiltration condition. Therefore, the infiltration curve obtained based on multiple evaluation moments and multiple first concentricity differences can show the law of change of the infiltration condition at the evaluation moment.

[0208] Schematically, taking the preset threshold value of 0 as an example, if the difference in the first concentricity is 0, that is, the first concentricity is equal to the second concentricity, it means that the wetting condition of the cylindrical battery cell is the above-mentioned first wetting condition, that is, the electrolyte completely penetrates the cylindrical battery cell; if the difference in the first concentricity is not 0, that is, the first concentricity is not equal to the second concentricity, it means that the wetting condition of the cylindrical battery cell is the above-mentioned second wetting condition, that is, the electrolyte has not yet completely penetrated the cylindrical battery cell, etc.

[0209] In an optional embodiment, before the cylindrical battery cell is infiltrated with the electrolyte, a first scan cross section corresponding to the battery cell end of the cylindrical battery cell is obtained, and a second scan cross section corresponding to the battery cell middle of the cylindrical battery cell is obtained.

[0210] Illustratively, when the electrolyte has not yet been injected into the cylindrical battery cell, a first scanning cross section at the end of the battery cell and a second scanning cross section at the middle of the battery cell are acquired by setting the scanning depth.

[0211] Optionally, the scanning depth of the first scanning cross section is the same as the scanning depth of the first infiltration cross section, and the scanning depth of the second scanning cross section is the same as the scanning depth of the second infiltration cross section. For example: if the first scanning cross section is obtained by scanning the cylindrical battery cell with a scanning depth of 1 / 6 of the length of the cylindrical battery cell as an example, then during the infiltration process, the cylindrical battery cell is also scanned with a scanning depth of 1 / 6 of the length of the cylindrical battery cell as an example to obtain the first infiltration cross section; similarly, if the second scanning cross section is obtained by scanning the cylindrical battery cell with a scanning depth of 3 / 7 of the length of the cylindrical battery cell as an example, then during the infiltration process, the cylindrical battery cell is also scanned with a scanning depth of 3 / 7 of the length of the cylindrical battery cell as an example to obtain the second infiltration cross section, etc.

[0212] In an optional embodiment, a third concentricity corresponding to the end of the battery cell is acquired based on the first scan cross section, and a fourth concentricity corresponding to the middle of the battery cell is acquired based on the second scan cross section.

[0213] Schematically, the first scanning cross section is used to characterize the nesting relationship between the winding core and the metal shell at the end of the cylindrical battery cell, and the second scanning cross section is used to characterize the nesting relationship between the winding core and the metal shell at the middle of the cylindrical battery cell.

[0214] Based on the first scanning cross-section, the third concentricity of the core center at the end of the battery cell relative to the center of the shell can be obtained. If the third concentricity is 0, it means that the core center and the shell center overlap, or, if the third concentricity is 0.005 mm, it means that there is a slight deviation between the core center and the shell center.

[0215] Similarly, based on the second scanning cross-section, the fourth concentricity of the core center at the middle of the battery cell relative to the center of the shell can be obtained. If the fourth concentricity is 0, it means that the core center and the shell center overlap, or, if the fourth concentricity is 0.003 mm, it means that there is a slight deviation between the core center and the shell center.

[0216] In an optional embodiment, the difference between the third concentricity and the fourth concentricity is obtained to obtain the difference in the second concentricity.

[0217] Indicatively, before the infiltration process is performed, the third concentricity and the fourth concentricity are most likely constant values ​​(such as not considering the influence of temperature, moisture, etc.), and the difference operation is performed on the third concentricity and the fourth concentricity to obtain the difference of the second concentricity. For example, the larger concentricity is used as the minuend and the smaller concentricity is used as the subtrahend to obtain the difference of the second concentricity. Optionally, the difference of the second concentricity is most likely to be 0, or it may be other smaller values ​​(such as considering the degree of offset when the core is nested in the metal shell or the irregularity of the core itself, etc.).

[0218] In an optional embodiment, the second concentricity difference is taken as a starting point, and the changes of multiple first concentricity differences at multiple evaluation moments are analyzed to obtain the infiltration curve.

[0219] Illustratively, when analyzing the changes of the differences of the first concentricities with the multiple evaluation moments, the difference of the second concentricities calculated when the electrolyte does not infiltrate the cylindrical battery cell is taken as the starting point, so as to obtain the wetting curve describing the whole process before and during the wetting.

[0220] In some embodiments, a wetting curve is displayed on the terminal as the wetting condition of the cylindrical battery cell to show the wetting uniformity of the cylindrical battery cell at multiple evaluation moments.

[0221] Optionally, in response to the difference between the first concentricity and the second concentricity at the second evaluation moment being less than a preset threshold, the wetting process of the cylindrical battery cell with the electrolyte is stopped.

[0222] Indicatively, the preset threshold is 0. When the wetting curve indicates that the difference in the first concentricity is 0 at the second evaluation moment, that is, the first concentricity is equal to the second concentricity, it means that the cylindrical battery cell is evenly infiltrated with the electrolyte. Therefore, the infiltration process can be stopped at the second evaluation moment or at any time after the second evaluation moment, such as: ending the injection process, closing the cylindrical battery cell, etc.

[0223] Optionally, in response to the difference between the first concentricity and the second concentricity at the second evaluation moment being less than a preset threshold, and the difference between the first concentricity and the second concentricity at the third evaluation moment being less than a preset threshold, the wetting process of the electrolyte infiltrating the cylindrical battery cell is stopped.

[0224] Among them, the third evaluation moment is the evaluation moment after the third evaluation moment; taking the preset threshold value of 0 as an example, when the wetting curve indicates that the difference in the first concentricity is 0 at the second evaluation moment, that is, the first concentricity is equal to the second concentricity, this means that the cylindrical battery cell is evenly infiltrated with the electrolyte, and the difference relationship between the first concentricity and the second concentricity can be judged again at the third evaluation moment after the second evaluation moment. If they are still the same, it means that the cylindrical battery cell is indeed evenly infiltrated with the electrolyte and not an accidental result. Therefore, the infiltration process can be stopped at the third evaluation moment or at any time after the third evaluation moment.

[0225] It is worth noting that the above are merely illustrative examples and are not limited to the embodiments of the present application.

[0226] In summary, the change in concentricity can be used to flexibly analyze the offset change of the core center relative to the shell center, so as to flexibly determine the degree of electrolyte infiltration of the cylindrical battery cell. This helps to understand the situation of electrolyte infiltration of the cylindrical battery cell more timely, achieve the purpose of non-destructive testing of the wettability of the cylindrical core, avoid the problem of needing to destroy the cylindrical battery cell to analyze the degree of infiltration, and also helps to effectively grasp the infiltration time of the cylindrical battery cell and improve the processing efficiency of the cylindrical battery cell infiltration process.

[0227] In the embodiments of the present application, the wetting curve is used to show the changes of the wetting condition at the evaluation time. The wetting curve can present the wetting process more intuitively, which is convenient for the battery preparation personnel to understand the degree of the cylindrical battery cell being infiltrated by the electrolyte in a more timely manner, so as to stop the wetting process in time and improve the wetting efficiency.

[0228] In an optional embodiment, the method for obtaining the wetting condition of the battery cell can also be called a "method for evaluating the complete wetting of cylindrical battery cells". Taking into account the problem that effective online detection methods cannot be performed on a normal production line due to the protection of the steel shell of the cylindrical battery cell, a process for online detection of whether the cylindrical battery cell is completely wetted by the electrolyte is introduced.

[0229] In schematic form, the wettability of the electrolyte to the core plays an important role in lithium-ion batteries. If the core is not completely wetted (i.e., the wet time is short), the charging and discharging of the incompletely wetted core will cause lithium deposition in the middle of the cylindrical battery cell, which poses a major safety hazard. In addition, high internal resistance will also lead to a low cycle life of the battery. If the wet time is extended, it will cause a waste of production line costs.

[0230] Among them, lithium plating refers to the phenomenon that during the charging process of lithium-ion batteries, due to certain abnormal conditions, lithium ions cannot be embedded in the negative electrode material, and metallic lithium is formed on the surface of the negative electrode. This phenomenon usually occurs when there is insufficient space for lithium embedding in the negative electrode, the embedding resistance is large, or the charging is too fast. Lithium plating will lead to a decrease in battery performance, shorten the cycle life, limit the fast charging capacity, and may cause safety problems such as combustion and explosion.

[0231] Optionally, a method for obtaining the wetting condition of a battery cell is described as follows.

[0232] (1) Taking the 18650 cylindrical battery cell as an example, the outer diameter of the winding core is usually 0.5 mm smaller than the inner diameter of the steel shell (the metal shell is a steel shell) to prevent the winding core from being punctured by the steel shell when entering the shell;

[0233] (2) The thickness of the positive electrode, negative electrode and diaphragm of the cylindrical battery cell will expand after absorbing liquid;

[0234] (3) The liquid absorption process of the cylindrical battery core is from both ends to the middle. Based on the above-mentioned small expansion coefficient of the single-layer positive electrode sheet and the negative electrode sheet, the overall expansion is superimposed after being rolled into a core. The concentricity of the core after liquid absorption (the outermost negative electrode) and the steel shell is used to measure the wettability (degree of wetting) of the core.

[0235] (4) Use X-ray (X-ARY) to take cross-sectional images (wet cross-section) of the end of the cylindrical battery cell (0-1 / 5 of the core length) and the middle of the battery cell (2 / 5-3 / 5 of the core length) after liquid injection.

[0236] 4.1. Perform CT scan on the 18650 cylindrical battery before filling, take the head cross section (first scanning cross section) and the middle cross section (second scanning cross section), calculate the concentricity (third concentricity and fourth concentricity) of the core and the head and tail of the steel shell respectively, and record it as a, a is the difference between the third concentricity and the fourth concentricity, that is, the difference a of the second concentricity;

[0237] 4.2. Fill the battery cell with liquid and apply vacuum pressure to make the electrolyte soak the winding core;

[0238] 4.3. After the injection is completed, CT scanning is used to take pictures of the head cross section (first infiltration cross section) and the middle cross section (second infiltration cross section), and the concentricity of the core and the head and tail of the steel shell is calculated again, which is recorded as b. a is the difference between the first concentricity and the second concentricity, that is, the difference of the first concentricity b;

[0239] 4.4. When the first concentricity between the core head and the steel shell after injection is the same as the second concentricity between the core middle and the steel shell, that is, b=0, it is determined that the core is fully infiltrated, the infiltration process can be stopped and the next step of charging and discharging process can be carried out.

[0240] It is worth noting that the above are merely illustrative examples and are not limited to the embodiments of the present application.

[0241] In summary, the change in concentricity can be used to flexibly analyze the offset change of the core center relative to the shell center, so as to flexibly determine the degree of electrolyte infiltration of the cylindrical battery cell, such as incomplete infiltration or complete infiltration. This helps to understand the situation of electrolyte infiltration of the cylindrical battery cell more timely, achieve the purpose of non-destructive testing of the wettability of the cylindrical core, avoid the problem of destroying the cylindrical battery cell to analyze the degree of infiltration, and also help to effectively grasp the infiltration time of the cylindrical battery cell and improve the processing efficiency of the cylindrical battery cell infiltration process.

[0242] In the embodiments of the present application, the wettability of the cylindrical core is non-destructively tested, which reduces damage to the battery cells and avoids waste of the battery cells. The wetting time of the battery cells can also be tested in a timely manner, reducing the turnaround time required for complete wetting.

[0243] Please refer to Fig.10 , which shows a structural block diagram of a device for obtaining the cell wetting condition provided by an exemplary embodiment of the present application, the device includes the following modules:

[0244] The collection module 1010 is used to collect a first infiltration cross section corresponding to the end of the cylindrical battery cell during the electrolyte infiltration process; and collect a second infiltration cross section corresponding to the middle of the cylindrical battery cell during the electrolyte infiltration process; wherein the cylindrical battery cell includes a winding core and a metal shell, the metal shell is used to wrap the winding core, and the outer diameter of the winding core is smaller than the inner diameter of the metal shell;

[0245] An acquisition module 1020 is used to acquire a first concentricity corresponding to the end of the battery cell based on the first wetted cross section, and to acquire a second concentricity corresponding to the middle of the battery cell based on the second wetted cross section; wherein the concentricity is used to characterize the degree of deviation of the center of the winding core relative to the center of the shell in the wetted cross section;

[0246] The display module 1030 is used to display the wetting condition of the cylindrical battery cell based on the difference between the first concentricity and the second concentricity, and the wetting condition is used to indicate the degree to which the electrolyte infiltrates the cylindrical battery cell.

[0247] In an optional embodiment, the acquisition module 1020 is further used to determine a first core region corresponding to the core and a first shell region corresponding to the metal shell from the first wetted cross section; and use a first distance by which the center of the core in the first core region is offset from the center of the shell in the first shell region as the first concentricity corresponding to the cell end;

[0248] The acquisition module 1020 is also used to determine the second core area corresponding to the core and the second shell area corresponding to the metal shell from the second wetting cross section; and use the second distance by which the center of the core in the second core area is offset relative to the center of the shell in the second shell area as the second concentricity corresponding to the middle of the battery cell.

[0249] In an optional embodiment, the acquisition module 1020 is further used to determine a regional geometric center from the first core region as the core center, and to determine a regional geometric center from the first shell region as the shell center; and to use the first distance offset between the core center and the shell center as the first concentricity corresponding to the cell end;

[0250] The acquisition module 1020 is also used to determine the regional geometric center from the second core area as the core center, and to determine the regional geometric center from the second shell area as the shell center; and to use the second distance that the core center is offset relative to the shell center as the second concentricity corresponding to the middle of the battery cell.

[0251] In an optional embodiment, the acquisition module 1010 is also used to select a first preset cell length from the cylindrical battery cell as the cell end with the positive electrode of the cylindrical battery cell as the starting point; select a second preset cell length from the cylindrical battery cell as the middle of the battery cell with the center point of the cylindrical battery cell as the center, and the cell end is independent of the cell middle; in the process of the cylindrical battery cell being infiltrated by the electrolyte, a circular cross-section is collected from the cell end as the first infiltration cross-section, and a circular cross-section is collected from the middle of the battery cell as the second infiltration cross-section.

[0252] In an optional embodiment, the acquisition module 1010 is also used to perform a tomographic scan on the cylindrical battery cell at a first scanning depth to obtain the first wetting cross-section corresponding to the end of the battery cell, and the first scanning depth is a scanning depth that conforms to the interval where the end of the battery cell is located; and to perform a tomographic scan on the cylindrical battery cell at a second scanning depth to obtain the second wetting cross-section corresponding to the middle of the battery cell, and the second scanning depth is a scanning depth that conforms to the interval where the middle of the battery cell is located.

[0253] In an optional embodiment, the display module 1030 is also used to display that the cylindrical battery cell is in a first wetting condition when the difference between the first concentricity and the second concentricity is less than a preset threshold value, and the first wetting condition indicates that the degree of wetting of the cylindrical battery cell by the electrolyte meets the wetting requirements; or, when the difference between the first concentricity and the second concentricity is not less than the preset threshold value, display that the cylindrical battery cell is in a second wetting condition, and the second wetting condition indicates that the degree of wetting of the cylindrical battery cell by the electrolyte does not meet the wetting requirements.

[0254] In an optional embodiment, the cylindrical battery core includes a positive terminal and a negative terminal, and the electrolyte infiltrates from at least one end of the cylindrical battery core toward the middle of the winding core.

[0255] In an optional embodiment, the acquisition module 1010 is further used to collect a first infiltration cross section corresponding to the end of the battery cell at multiple evaluation moments during the electrolyte infiltration process of the cylindrical battery cell; and a second infiltration cross section corresponding to the middle of the battery cell at the multiple evaluation moments;

[0256] The acquisition module 1020 is also used to acquire, for a first evaluation moment among the multiple evaluation moments, the first concentricity of the first infiltration cross section acquired at the first evaluation moment, and to acquire the second concentricity of the second infiltration cross section acquired at the first evaluation moment.

[0257] In an optional embodiment, the acquisition module 1020 is also used to obtain the difference between the first concentricity and the second concentricity at multiple evaluation moments, and obtain multiple first concentricity differences; wherein the multiple evaluation moments and the multiple first concentricity differences correspond one to one; analyze the changes of the multiple first concentricity differences with the multiple evaluation moments to obtain a wetting curve, and the wetting curve is used to describe the change pattern of the wetting condition of the cylindrical battery cell with the evaluation moment.

[0258] In an optional embodiment, the acquisition module 1020 is also used to obtain a first scanning cross-section corresponding to the cell end of the cylindrical battery cell and a second scanning cross-section corresponding to the cell middle of the cylindrical battery cell before the cylindrical battery cell is infiltrated with the electrolyte; obtain a third concentricity corresponding to the cell end based on the first scanning cross-section, and obtain a fourth concentricity corresponding to the middle of the battery cell based on the second scanning cross-section; obtain the difference between the third concentricity and the fourth concentricity to obtain the second concentricity difference; take the second concentricity difference as the starting point, analyze the changes of the multiple first concentricity differences with the multiple evaluation moments, and obtain the infiltration curve.

[0259] In summary, the change in concentricity can be used to flexibly analyze the offset change of the core center relative to the shell center, so as to flexibly determine the degree of electrolyte infiltration of the cylindrical battery cell. This helps to understand the situation of electrolyte infiltration of the cylindrical battery cell more timely, achieve the purpose of non-destructive testing of the wettability of the cylindrical core, avoid the problem of needing to destroy the cylindrical battery cell to analyze the degree of infiltration, and also helps to effectively grasp the infiltration time of the cylindrical battery cell and improve the processing efficiency of the cylindrical battery cell infiltration process.

[0260] It should be noted that the device for obtaining the wetness of a battery cell provided in the above embodiment is only illustrated by the division of the above functional modules. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the device for obtaining the wetness of a battery cell provided in the above embodiment and the method for obtaining the wetness of a battery cell are of the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.

[0261] Fig.11 The block diagram of the structure of an electronic device 1100 provided by an exemplary embodiment of the present application is shown. The electronic device 1100 may be a portable mobile terminal, such as a smart phone, a vehicle-mounted terminal, a tablet computer, an MP3 player (Moving Picture Experts Group Audio Layer III), an MP4 player (Moving Picture Experts Group Audio Layer IV), a laptop computer or a desktop computer. The electronic device 1100 may also be called a user device, a portable terminal, a laptop terminal, a desktop terminal or other names.

[0262] Typically, the electronic device 1100 includes a processor 1101 and a memory 1102 .

[0263] The processor 1101 may include one or more processing cores. The processor 1101 may also include a main processor and a coprocessor.

[0264] The memory 1102 may include one or more computer-readable storage media, which may be non-transitory. The memory 1102 may also include a high-speed random access memory, and a non-volatile memory, such as one or more disk storage devices, flash memory storage devices. In some embodiments, the non-transitory computer-readable storage medium in the memory 1102 is used to store at least one instruction, which is used to be executed by the processor 1101 to implement the method for obtaining the cell wetting condition provided in the method embodiment of the present application.

[0265] In some embodiments, the electronic device 1100 further includes one or more sensors, including but not limited to: a proximity sensor, a gyroscope sensor, and a pressure sensor.

[0266] In some embodiments, the electronic device 1100 further includes other components, which can be understood by those skilled in the art. Fig.11 The structure shown in the figure does not constitute a limitation on the electronic device 1100, and may include more or less components than those shown in the figure, or combine certain components, or adopt a different component arrangement.

[0267] The embodiment of the present application also provides a computer device, which can be implemented as follows: Figure 1 The computer device includes a processor and a memory, wherein at least one instruction, at least one program, code set or instruction set is stored in the memory, and the at least one instruction, at least one program, code set or instruction set is loaded and executed by the processor to implement the method for obtaining the cell infiltration condition provided by the above-mentioned method embodiments.

[0268] An embodiment of the present application also provides a computer-readable storage medium, on which is stored at least one instruction, at least one program, code set or instruction set, and the at least one instruction, at least one program, code set or instruction set is loaded and executed by a processor to implement the method for obtaining the cell wetting condition provided in the above-mentioned method embodiments.

[0269] The embodiments of the present application also provide a computer program product or a computer program, which includes a computer instruction stored in a computer-readable storage medium. The processor of the computer device reads the computer instruction from the computer-readable storage medium, and the processor executes the computer instruction, so that the computer device executes the method for obtaining the cell wetting condition described in any of the above embodiments.

[0270] Optionally, the computer readable storage medium may include: a read-only memory (ROM), a random access memory (RAM), a solid state drive (SSD), or an optical disk. Among them, the random access memory may include a resistance random access memory (ReRAM) and a dynamic random access memory (DRAM). The serial numbers of the above embodiments of the present application are only for description and do not represent the advantages and disadvantages of the embodiments.

[0271] Those skilled in the art can understand that all or part of the steps of implementing the above embodiments can be completed by hardware, or by a program to instruct the relevant hardware to complete, and the program can be stored in a computer-readable storage medium, and the above-mentioned storage medium can be a read-only memory, a disk or an optical disk, etc. The above description is only an optional embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for obtaining the wetting condition of a battery cell, characterized in that: The method comprises: Collecting a first infiltration cross section corresponding to the end of the cylindrical battery cell during the electrolyte infiltration process; and collecting a second infiltration cross section corresponding to the middle of the cylindrical battery cell during the electrolyte infiltration process; wherein the cylindrical battery cell comprises a winding core and a metal shell, the metal shell is used to wrap the winding core, and the outer diameter of the winding core is smaller than the inner diameter of the metal shell; Based on the first wetted cross section, a first concentricity corresponding to the end of the battery cell is obtained, and based on the second wetted cross section, a second concentricity corresponding to the middle of the battery cell is obtained; wherein the concentricity is used to characterize the degree of deviation of the center of the winding core relative to the center of the shell in the wetted cross section; Based on the difference between the first concentricity and the second concentricity, the wetting condition of the cylindrical battery core is displayed, and the wetting condition is used to characterize the degree to which the electrolyte infiltrates the cylindrical battery core.

2. The method according to claim 1, characterized in that The obtaining a first concentricity corresponding to the battery cell end based on the first wetting cross section includes: Determine a first winding core region corresponding to the winding core and a first shell region corresponding to the metal shell from the first wetted cross section; use a first distance offset between the winding core center in the first winding core region and the shell center in the first shell region as the first concentricity corresponding to the cell end; The obtaining a second concentricity corresponding to the middle of the battery core based on the second wetting cross section includes: Determine the second core area corresponding to the core and the second shell area corresponding to the metal shell from the second wetting cross section; take the second distance by which the center of the core in the second core area is offset relative to the center of the shell in the second shell area as the second concentricity corresponding to the middle of the battery cell.

3. The method according to claim 2, characterized in that The method of offsetting the center of the winding core in the first winding core region relative to the center of the shell in the first shell region by a first distance as the first concentricity corresponding to the end of the battery cell comprises: Determine a regional geometric center from the first core region as the core center, and determine a regional geometric center from the first shell region as the shell center; use the first distance that the core center is offset from the shell center as the first concentricity corresponding to the cell end; The method of offsetting the center of the winding core in the second winding core region relative to the center of the shell in the second shell region by a second distance as the second concentricity corresponding to the middle of the battery cell comprises: Determine a regional geometric center from the second core area as the core center, and determine a regional geometric center from the second shell area as the shell center; and use the second distance that the core center is offset relative to the shell center as the second concentricity corresponding to the middle of the battery cell.

4. The method according to any one of claims 1 to 3, characterized in that: The collecting of a first wet cross section corresponding to an end of the cylindrical battery cell during the electrolyte infiltration process; and the collecting of a second wet cross section corresponding to a middle portion of the cylindrical battery cell during the electrolyte infiltration process include: Taking the positive electrode of the cylindrical battery cell as the starting point, selecting a first preset battery cell length from the cylindrical battery cell as the battery cell end; Taking the center point of the cylindrical battery cell as the center, a second preset battery cell length is selected from the cylindrical battery cell as the middle of the battery cell, and the battery cell end is independent of the middle of the battery cell; When the cylindrical battery cell is infiltrated by the electrolyte, a circular cross section is collected from the end of the battery cell as the first infiltration cross section, and a circular cross section is collected from the middle of the battery cell as the second infiltration cross section.

5. The method according to claim 4, characterized in that In the process of the cylindrical battery core being infiltrated by the electrolyte, collecting a circular cross section from the end of the battery core as the first infiltration cross section, and collecting a circular cross section from the middle of the battery core as the second infiltration cross section, comprising: Performing a tomographic scan on the cylindrical battery cell at a first scanning depth to obtain the first wetting cross section corresponding to the battery cell end, wherein the first scanning depth is a scanning depth that matches the interval where the battery cell end is located; Perform a tomographic scan on the cylindrical battery cell at a second scanning depth to obtain the second wetting cross section corresponding to the middle of the battery cell, wherein the second scanning depth is a scanning depth that matches the interval where the middle of the battery cell is located.

6. The method according to any one of claims 1 to 3, characterized in that: The displaying of the wetting condition of the cylindrical battery core based on the difference between the first concentricity and the second concentricity includes: When the difference between the first concentricity and the second concentricity is less than a preset threshold, it is indicated that the cylindrical battery cell is in a first wetting condition, and the first wetting condition indicates that the degree of wetting of the cylindrical battery cell by the electrolyte meets the wetting requirement; or When the difference between the first concentricity and the second concentricity is not less than the preset threshold, it is shown that the cylindrical battery cell is in a second wetting condition, and the second wetting condition indicates that the degree of wetting of the cylindrical battery cell by the electrolyte does not meet the wetting requirements.

7. The method according to any one of claims 1 to 3, characterized in that: The cylindrical battery core comprises a positive terminal and a negative terminal, and the electrolyte infiltrates from at least one end of the cylindrical battery core toward the middle of the winding core.

8. The method according to any one of claims 1 to 3, characterized in that: The method further comprises: Collecting the first infiltration cross-section corresponding to the end of the battery cell at multiple evaluation moments during the infiltration of the cylindrical battery cell in the electrolyte; and the second infiltration cross-section corresponding to the middle of the battery cell at the multiple evaluation moments; For a first evaluation moment among the multiple evaluation moments, the first concentricity of the first infiltration cross section acquired at the first evaluation moment is acquired, and the second concentricity of the second infiltration cross section acquired at the first evaluation moment is acquired.

9. The method according to any one of claims 1 to 3, characterized in that: The method further comprises: Obtaining the difference between the first concentricity and the second concentricity at multiple evaluation moments to obtain multiple first concentricity differences; wherein the multiple evaluation moments and the multiple first concentricity differences correspond one to one; The variation of the differences between the plurality of first concentricities with the plurality of evaluation moments is analyzed to obtain a wetting curve, wherein the wetting curve is used to describe the variation law of the wetting condition of the cylindrical battery cell with the evaluation moment.

10. The method according to claim 9, characterized in that The method further comprises: Before the cylindrical battery cell is infiltrated with the electrolyte, a first scan cross section corresponding to the battery cell end of the cylindrical battery cell is obtained, and a second scan cross section corresponding to the battery cell middle of the cylindrical battery cell is obtained; Acquire a third concentricity corresponding to the end of the battery cell based on the first scanned cross section, and acquire a fourth concentricity corresponding to the middle of the battery cell based on the second scanned cross section; Obtaining a difference between the third concentricity and the fourth concentricity to obtain a difference in the second concentricity; Taking the second concentricity difference as a starting point, the variation of the first concentricity differences with the evaluation moments is analyzed to obtain the infiltration curve.

11. A device for obtaining the wetness of a battery cell, characterized in that: The device comprises: A collection module, used to collect a first infiltration cross section corresponding to the end of the cylindrical battery cell during the electrolyte infiltration process; and to collect a second infiltration cross section corresponding to the middle of the cylindrical battery cell during the electrolyte infiltration process; wherein the cylindrical battery cell comprises a winding core and a metal shell, the metal shell is used to wrap the winding core, and the outer diameter of the winding core is smaller than the inner diameter of the metal shell; An acquisition module, configured to acquire a first concentricity corresponding to the end of the battery cell based on the first wetted cross section, and to acquire a second concentricity corresponding to the middle of the battery cell based on the second wetted cross section; wherein the concentricity is used to characterize the degree of deviation of the center of the winding core relative to the center of the shell in the wetted cross section; The display module is used to display the wetting condition of the cylindrical battery core based on the difference between the first concentricity and the second concentricity, and the wetting condition is used to characterize the degree to which the electrolyte infiltrates the cylindrical battery core.

12. A computer device, characterized in that: The computer device includes a processor and a memory, wherein the memory stores at least one program, and the at least one program is loaded and executed by the processor to implement the method for obtaining the cell wetting condition as described in any one of claims 1 to 10.

13. A computer-readable storage medium, characterized in that: At least one program is stored in the storage medium, and the at least one program is loaded and executed by the processor to implement the method for obtaining the wetting condition of the battery cell as described in any one of claims 1 to 10.

14. A computer program product, characterized in that It comprises computer instructions, and when the computer instructions are executed by a processor, the method for obtaining the cell wetting condition as described in any one of claims 1 to 10 is implemented.

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