Battery cell and preparation method therefor, battery and electric device

Abstract

The present application relates to a battery cell (20) and a preparation method therefor, a battery (100) and an electric device. The preparation method for the battery cell (20) comprises: determining that the battery cell (20) is in an uncharged state; spraying an insulating material onto at least a partial region of the outer surface of a case (22) of the battery cell (20) by means of an electrostatic spraying method; curing the region, onto which the insulating material is sprayed, of the case (22), so as to obtain the battery cell (20) containing an insulating layer (24); and injecting an electrolyte into the battery cell (20) containing the insulating layer (24). In the preparation method for the battery cell (20) of the present application, by subjecting the battery cell (20) in the uncharged state to insulating spraying, which may be performed by means of an electrostatic spraying method, the utilization rate of a coating of the insulating layer (24) during a production process of the battery (100) can be improved, and the production costs can be reduced.

Description

Battery monomer and preparation method thereof, battery and power-consuming device

[0001] Cross-references

[0002] This application refers to Chinese Patent Application No. 202311622322.5 filed on November 29, 2023, entitled “Battery Cell and Preparation Method thereof, Battery and Electrical Device”, which is incorporated into this application in its entirety by reference. Technical Field

[0003] The present application relates to the field of batteries, and in particular to a battery cell and a preparation method thereof, a battery, and an electrical device. Background Art

[0004] As a crucial component of new energy vehicles, the lifespan and safety of power batteries are crucial. These are influenced not only by the electrode materials but also by the battery casing structure and insulation properties. To prevent safety issues like scratches and short circuits, an insulating layer is applied to the outer surface of the battery casing.

[0005] In some cases, an insulating material is coated on the surface of the battery casing by spraying. How to improve the coating utilization rate of the insulating layer of the battery casing in the battery production process has become an urgent problem to be solved.

[0006] Summary of the Invention

[0007] In view of the above problems, the present application provides a battery cell and a preparation method thereof, a battery and an electrical device, which can improve the coating utilization rate of the battery shell insulation layer in the battery production process.

[0008] In a first aspect, the present application provides a method for preparing a battery cell, the method comprising:

[0009] Make sure the battery cell is in a non-charged state;

[0010] Spraying the insulating material onto at least a portion of the outer surface of the battery cell shell by electrostatic spraying;

[0011] Performing a curing treatment on the area of ​​the shell where the insulating material is sprayed to obtain a battery cell including an insulating layer;

[0012] An electrolyte is injected into the battery cell including the insulating layer.

[0013] In the technical solution of the embodiment of the present application, by performing insulation spraying when the battery cell is in an uncharged state, electrostatic spraying can be used for insulation spraying, which can improve the paint utilization rate of the battery shell insulation layer in the battery production process, reduce production costs, and simplify the spraying process, improve production efficiency, and the insulation layer formed by electrostatic spraying is of higher quality, which is conducive to improving the uniformity of the insulation performance of the insulation layer, better insulation performance, longer service life, and improved safety performance of the battery cell.

[0014] In some embodiments, the insulating material is a light-curable insulating resin material; curing the area of ​​the housing sprayed with the insulating material comprises:

[0015] The area of ​​the housing where the insulating material is sprayed is irradiated with ultraviolet light to solidify the insulating material.

[0016] With such an arrangement, the insulating material can be quickly solidified in a short time, greatly improving the production efficiency of battery cells, being beneficial to the large-scale mass production of battery cells, and being energy-saving, environmentally friendly, economical and adaptable.

[0017] In some embodiments, the light-curable insulating resin material includes a UV-curable coating. This allows for a controlled appearance of the insulating layer without affecting the assembly of the battery cells. The UV-curable coating exhibits strong adhesion and resists detachment, significantly improving the insulation performance of the housing and ensuring stable insulation performance.

[0018] In some embodiments, the UV irradiation time is 3 seconds to 30 seconds. In this way, the insulating material can be quickly cured in a short time, greatly improving the production efficiency of the battery cells and facilitating large-scale mass production of battery cells.

[0019] In some embodiments, the insulating material is a water-based paint or a solvent-based paint; curing the area of ​​the housing sprayed with the insulating material includes:

[0020] The battery cell is baked to solidify the insulating material; wherein the baking temperature is greater than 60° C. and less than 200° C.

[0021] With this arrangement, the insulating material can be dried and solidified quickly, and the production process can be selectively expanded significantly, significantly improving the coating performance, reducing the process time, greatly improving production efficiency, and reducing production costs. It is suitable for high-speed automated production and is conducive to large-scale mass production of battery cells.

[0022] In some embodiments, the baking temperature is greater than 100° C. and less than 180° C. This allows for a significantly expanded production process, significantly improving coating performance, reducing process time, significantly increasing production efficiency, and reducing production costs. This makes the process suitable for high-speed automated production and facilitates large-scale mass production of battery cells.

[0023] In some embodiments, after obtaining a battery cell including an insulating layer and before injecting an electrolyte into the battery cell including the insulating layer, the method further includes:

[0024] Perform insulation testing on the housing.

[0025] By testing the insulation performance of the shell before injecting the electrolyte, the battery cells whose insulation performance does not meet the requirements can be identified and eliminated, effectively ensuring that the insulation performance meets the product requirements, and avoiding the injection of electrolyte into the battery cells that do not meet the requirements, preventing electrolyte waste, effectively saving materials and reducing production costs.

[0026] In some embodiments, before spraying the insulating material onto at least a portion of the outer surface of the battery cell housing by electrostatic spraying, the method further includes:

[0027] Clean the outer surface of the shell.

[0028] By cleaning the outer surface of the shell, impurities such as dust, rust or stains on the outer surface of the shell can be removed, which is beneficial to improving the adhesion between the insulation layer and the outer surface of the shell, making it less likely to fall off, improving the quality of the insulation layer, and achieving better insulation performance and longer service life.

[0029] In some embodiments, the cleaning process includes any one or more of sandblasting, plasma cleaning, and laser cleaning. In this way, the outer surface of the housing can be cleaned with good cleaning effect.

[0030] In some embodiments, determining that a battery cell is in an uncharged state includes: winding or stacking a positive electrode sheet, a negative electrode sheet, and a separator to form a battery cell assembly, placing the battery cell assembly into a housing, and then capping and welding end caps to openings in the housing to obtain a battery cell that does not contain electrolyte. Thus, since the battery cell does not contain electrolyte, it is in an uncharged state.

[0031] In a second aspect, the present application provides a battery cell, which is prepared according to the battery cell preparation method in any of the above embodiments; the battery cell includes: a shell, an insulating layer is provided on at least a portion of the outer surface of the shell; a battery cell assembly, the battery cell assembly is accommodated in the shell; and an end cover, the end cover covers the opening of the shell.

[0032] In some embodiments, the thickness of the insulating layer on the housing is 80 to 200 microns. This configuration provides the housing with excellent insulation properties, ensuring the safety of the battery cells. Controlling the thickness of the insulating layer also allows for better control of the appearance and size of the battery cells, facilitating subsequent assembly of the battery cells, improving production efficiency, ensuring a high yield rate, and saving materials and reducing production costs.

[0033] In some embodiments, the thickness of the insulating layer is 110 to 120 microns. This configuration helps to better balance the insulation performance of the housing, the appearance and volume of the battery cell, and the yield rate, and reduces production costs, making it suitable for large-scale mass production.

[0034] In a third aspect, the present application provides a battery, which includes the battery cell in any of the above embodiments.

[0035] In a fourth aspect, the present application provides an electrical device, which includes the battery in the above embodiment or the battery cell in any of the above embodiments, and the battery and the battery cell are used to provide electrical energy.

[0036] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on the drawings without inventive work. In the drawings:

[0038] FIG1 is a schematic structural diagram of a vehicle according to some embodiments of the present application.

[0039] FIG2 is a schematic diagram of the exploded structure of a battery according to some embodiments of the present application.

[0040] FIG3 is a schematic diagram of the exploded structure of a battery cell according to some embodiments of the present application.

[0041] FIG4 is a schematic flow chart of a method for preparing a battery cell according to some embodiments of the present application.

[0042] FIG5 is a schematic diagram of a method for measuring the thickness of an insulating layer on a battery cell according to some embodiments of the present application.

[0043] Figure 1000, vehicle; 100, battery; 200, controller; 300, motor; 10, housing; 11, first part; 12, second part; 20, battery cell; 21, end cover; 21a, electrode terminal; 22, housing; 23, battery cell assembly; 23a, tab; 24, insulation layer; 401, measuring probe. DETAILED DESCRIPTION

[0044] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0045] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0047] In the description of the embodiments of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0048] In the description of the embodiments of the present application, the terms "first" and "second" are used only for descriptive purposes to distinguish different objects, and should not be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the embodiments of the present application, the meaning of "plurality" is at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0049] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0050] In the description of the embodiments of this application, unless otherwise expressly specified or limited, the terms "installed," "connected," "connected," "fixed," etc. should be understood in a broad sense. For example, the connection may be fixed, removable, or integrated; it may be mechanical or electrical; it may be directly connected or indirectly connected through an intermediate medium; it may be internal communication between two components or an interactive relationship between two components, unless otherwise expressly specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0051] In the description of the embodiments of this application, unless otherwise explicitly specified or limited, when a first feature is "above" or "below" a second feature, it can mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it can mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it can mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0052] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0053] Currently, market developments indicate that power batteries are becoming increasingly widely used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As power battery applications continue to expand, market demand is also growing.

[0054] As a crucial component of new energy vehicles, the lifespan and safety of power batteries are crucial. These are influenced not only by the electrode materials but also by the battery casing structure and insulation properties. To prevent safety issues like scratches and short circuits, an insulating layer is typically placed on the outer surface of the battery casing.

[0055] In the related art, the positive electrode sheet, negative electrode sheet, separator, and housing without an insulating layer are usually assembled to form a battery cell. Then, electrolyte is injected into the battery cell to obtain an assembled battery. The outer surface of the assembled battery is then subjected to insulation spraying, and after curing, an assembled battery containing an insulating layer is obtained. However, since the insulation spraying is performed on an assembled battery containing electrolyte, and the assembled battery containing electrolyte is charged, for safety reasons, the insulation spraying at this time can only be performed using air spraying, not electrostatic spraying. However, air spraying has a low paint utilization rate, resulting in material waste and high production costs.

[0056] In order to improve the utilization rate of the coating and reduce production costs, electrostatic powder can be sprayed on the outer surface of the shell to form an insulating layer, and then the positive electrode sheet, negative electrode sheet, diaphragm and other components can be assembled into the shell, and then the top cover is welded to the shell, and finally the electrolyte is injected into the shell to obtain an assembled battery. However, spraying the battery shell first requires reserving the electrode welding position, the spraying process is complicated, and the reserved unsprayed position requires a subsequent step of wrapping insulating tape, which increases the process steps and reduces production efficiency. In addition, since the welding process will generate welding sparks, the temperature of the welding sparks is very high, which can easily ablate the insulating layer and form multiple tiny dot-shaped depressions on the surface of the insulating layer. These depressions not only affect the surface flatness of the insulating layer, but also affect the uniformity of the insulating performance of the entire insulating layer.

[0057] Based on the above considerations, a method for preparing battery cells was designed to improve the coating utilization rate of the battery case insulation layer during the battery production process. This method adjusts the process sequence of the electrolyte injection process and the insulation spraying process during the battery production process. Specifically, after the positive electrode sheet, negative electrode sheet, separator, and shell without the insulation layer are assembled to form the battery cell, the electrolyte injection process is temporarily suspended, thereby obtaining a battery cell without electrolyte. Because the battery cell without electrolyte is uncharged, electrostatic spraying can be used for insulation spraying. After the spraying is cured, electrolyte injection is performed to obtain a battery cell containing electrolyte. This can improve the coating utilization rate of the battery case insulation layer during the battery production process.

[0058] The battery cell preparation method disclosed in the embodiments of the present application is used for preparing battery cells, which is beneficial for improving coating utilization, reducing production costs, simplifying the spraying process, improving production efficiency, and enhancing the uniformity of the insulation performance of the insulation layer.

[0059] The battery cells disclosed in the embodiments of this application can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft. A power supply system comprising the battery cells and batteries disclosed in this application can be used to reduce costs and improve insulation performance.

[0060] The present invention provides an electric device that uses a battery as a power source. The electric device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, etc. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0061] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device in some embodiments of the present application.

[0062] Please refer to Figure 1, which is a schematic structural diagram of a vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0063] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0064] Please refer to Figure 2, which is an exploded view of a battery 100 provided in some embodiments of the present application. The battery 100 includes a housing 10 and a battery cell 20, with the battery cell 20 housed within the housing 10. The housing 10 provides a storage space for the battery cell 20 and can have various structures. In some embodiments, the housing 10 can include a first portion 11 and a second portion 12, which overlap each other and together define a storage space for the battery cell 20. The second portion 12 can be a hollow structure with one end open. The first portion 11 can be a plate-like structure, with the first portion 11 overlapping the open side of the second portion 12, so that the first portion 11 and the second portion 12 together define a storage space. Alternatively, the first portion 11 and the second portion 12 can each be a hollow structure with one end open, with the open side of the first portion 11 overlapping the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can have various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0065] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 20 may be housed within the housing 10. Alternatively, the battery 100 may be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid connection to form a battery module, which is then connected in series, in parallel, or in a hybrid connection to form a complete battery module, and then housed within the housing 10. The battery 100 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 20.

[0066] Each battery cell 20 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 can be cylindrical, flat, rectangular, or in other shapes. In other words, the battery cell 20 is not limited to a prismatic battery; it can also be a cylindrical battery.

[0067] Please refer to Figure 3, which is a schematic diagram of the exploded structure of a battery cell 20 provided in some embodiments of the present application. A battery cell 20 is the smallest unit that makes up a battery. As shown in Figure 3, a battery cell 20 includes an end cap 21, a housing 22, a cell assembly 23, and other functional components.

[0068] The end cap 21 is a component that covers the opening of the housing 22 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the end cap 21 can be adapted to the shape of the housing 22 to match the housing 22. In some embodiments, the end cap 21 can be made of a material with a certain hardness and strength (such as an aluminum alloy). This prevents the end cap 21 from deforming when subjected to compression or collision, giving the battery cell 20 greater structural strength and improved safety. The end cap 21 can be provided with functional components such as electrode terminals 21a. The electrode terminals 21a can be used to electrically connect to the battery cell assembly 23 to output or input electrical energy to the battery cell 20. In some embodiments, the end cap 21 can also be provided with a pressure relief mechanism for relieving internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The end cap 21 can also be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this embodiment of the present application does not impose any specific limitations on this. In some embodiments, an insulating member may be provided inside the end cap 21 to isolate the electrical connection components in the housing 22 from the end cap 21 to reduce the risk of short circuit. For example, the insulating member may be made of plastic, rubber, or the like.

[0069] The housing 22 is a component that cooperates with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can be used to accommodate the battery cell assembly 23, electrolyte, and other components. The housing 22 and end cap 21 can be separate components. An opening can be provided in the housing 22, and the end cap 21 is placed over the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and housing 22 can be integrated. In some embodiments, the end cap 21 and housing 22 can form a common connection surface before other components are inserted into the housing. When the interior of the housing 22 needs to be enclosed, the end cap 21 is placed over the housing 22. The housing 22 can have a variety of shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. In some embodiments, the shape of the housing 22 can be determined based on the specific shape and size of the battery cell assembly 23. The housing 22 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this embodiment of the present application does not impose any specific limitations on this.

[0070] The battery cell assembly 23 is a component in the battery cell 20 where electrochemical reactions occur. One or more battery cell assemblies 23 may be contained in the shell 22. The battery cell assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets. The parts of the positive and negative electrode sheets with active substances constitute the main body of the battery cell assembly 23, and the parts of the positive and negative electrode sheets without active substances each constitute a tab 23a. The positive and negative electrode tabs may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery, the positive active substance and the negative active substance react with the electrolyte, and the tab 23a connects to the electrode terminal 21a to form a current loop.

[0071] According to some embodiments of the present application, referring to FIG3 and further referring to FIG4, FIG4 shows a schematic flow diagram of a method for preparing a battery cell 20 in some embodiments of the present application. The present application provides a method for preparing a battery cell 20. The method for preparing a battery cell 20 includes the following steps:

[0072] Step S100, determining that the battery cell 20 is in an uncharged state;

[0073] Step S200 , spraying an insulating material onto at least a portion of the outer surface of the housing 22 of the battery cell 20 by electrostatic spraying;

[0074] Step S300 , curing the area of ​​the shell 22 where the insulating material is sprayed to obtain a battery cell 20 including an insulating layer;

[0075] Step S400 : injecting electrolyte into the battery cell 20 including the insulating layer.

[0076] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer is coated on the surface of the positive electrode current collector. The positive electrode current collector not coated with the positive electrode active material layer protrudes from the positive electrode current collector coated with the positive electrode active material layer. The positive electrode current collector not coated with the positive electrode active material layer constitutes the positive electrode tab. Taking lithium-ion batteries as an example, the positive electrode current collector can be aluminum foil, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. The positive electrode active material is stirred and mixed to obtain a positive electrode slurry. The positive electrode slurry is then coated on the surface of the positive electrode current collector. After baking and drying, it is cold pressed (rolled), pre-cut, and slit to produce a positive electrode sheet.

[0077] The negative electrode sheet consists of a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode current collector. The negative electrode current collector uncoated with the negative electrode active material layer protrudes from the negative electrode current collector coated with the negative electrode active material layer. The negative electrode current collector uncoated with the negative electrode active material layer forms the negative electrode tab. The negative electrode current collector can be copper foil, and the negative electrode active material can be carbon, silicon, or other materials. The negative electrode active material is stirred and mixed to produce a negative electrode slurry. The negative electrode slurry is then coated on the surface of the negative electrode current collector, baked and dried, and then cold pressed, pre-cut, and slit to produce the negative electrode sheet.

[0078] The diaphragm can be at least one of glass fiber cloth, non-woven fabric, polypropylene (PP) film and polyethylene (PE) film; the diaphragm can be a single-layer film or a multi-layer composite film, which is not limited here.

[0079] Determine that the battery cell 20 is in an uncharged state. In some embodiments, after assembling the positive electrode sheet, the negative electrode sheet, the separator and the shell 22 that does not contain an insulating layer, the electrolyte injection process is temporarily not performed, thereby obtaining a battery cell 20 that does not contain an electrolyte. Since it does not contain an electrolyte, the battery cell 20 is in an uncharged state. Specifically, the positive electrode sheet, the negative electrode sheet and the separator are wound or stacked to form a battery cell assembly 23, the battery cell assembly 23 is loaded into the shell 22, and the end cover 21 is covered and welded to the opening of the shell 22 to obtain a battery cell 20 that does not contain an electrolyte. In other embodiments, the battery cell 20 can contain a small amount of electrolyte or solid electrolyte, but be in an uncharged state.

[0080] Insulating materials refer to substances that are non-conductive or very slightly conductive under the action of DC voltage. Electrostatic spraying refers to a coating method that uses the principle of corona discharge to make atomized paint negatively charged under the action of a high-voltage DC electric field, and adsorbs on the positively charged surface of the coated object to discharge. Electrostatic spraying basically does not have the phenomenon of paint jet rebound and paint mist dispersion, and the paint mist loss is very small, so the paint utilization rate is high, which can reach 85% or more; and due to the action of the high-voltage electrostatic field, the paint particles are highly dispersed and distributed more evenly in the jet, so the coating formed on the surface of the coated object is also smoother and more uniform, the gloss and adhesion of the paint film are both higher, and the spraying efficiency is also higher. In this application, the coated object is the shell 22 of the battery cell 20. Since the battery cells 20 are uncharged, the insulating material can be applied to at least a portion of the outer surface of the housing 22 using electrostatic spraying. This improves coating utilization, reduces production costs, simplifies the process, and increases production efficiency. Furthermore, the insulating layer formed by electrostatic spraying is of higher quality, has better insulation performance, has greater adhesion to the housing 22, is more environmentally resistant, and has a longer service life. This application does not impose any specific restrictions on electrostatic spraying process parameters such as spray distance, time, voltage, and flow rate, and these parameters may be selected based on actual needs.

[0081] Curing the area of ​​the housing 22 coated with the insulating material involves converting the substances in the insulating material from low-molecular weight to high-molecular weight, which then dries to form a film. After curing, the insulating material coated on the outer surface of the housing 22 forms an insulating layer adhered to the outer surface of the housing 22, thereby obtaining a battery cell 20 including the insulating layer. This insulating layer insulates the metal housing 22 of the battery cell 20, effectively reducing safety issues such as scratches on the outer surface of the housing 22 or short circuits, thereby improving the safety of the battery cell 20.

[0082] After the sprayed insulating layer is cured, an electrolyte is injected into the battery cell 20 containing the insulating layer to obtain a battery cell 20 containing an electrolyte. In some embodiments, after the electrolyte is injected, vacuum packaging, chemical formation, sealing nail laser welding and other processes are also performed to obtain a battery cell 20. During the charge and discharge process of the battery cell 20, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet, and the electrolyte plays a role in conducting active ions between the positive electrode sheet and the negative electrode sheet. This application does not specifically limit the type of electrolyte, and it can be selected according to actual needs.

[0083] The preparation method of the battery cell 20 in the embodiment of the present application adjusts the process sequence of the electrolyte injection process and the insulation spraying process in the production process of the battery cell 20, and performs insulation spraying after the battery cell 20 is assembled and before the electrolyte is injected. Since the battery cell 20 is not charged at this time, electrostatic spraying can be used for insulation spraying, which can improve the coating utilization rate of the insulation layer of the battery shell 22 in the battery production process, reduce production costs, and simplify the spraying process, improve production efficiency, and the insulation layer formed by electrostatic spraying is higher in quality, which is beneficial to improving the uniformity of the insulation performance of the insulation layer, better insulation performance, longer service life, and improving the safety performance of the battery cell 20.

[0084] According to some embodiments of the present application, the insulating material is a light-curing insulating resin material; curing the area of ​​the housing 22 sprayed with the insulating material includes the following steps:

[0085] In step S310 , ultraviolet light is used to irradiate the area of ​​the housing 22 where the insulating material is sprayed, so as to solidify the insulating material.

[0086] Photocurable insulating resin materials are composed of resin monomers and prepolymers, contain reactive functional groups, and can undergo a polymerization reaction initiated by a photosensitizer under ultraviolet light to form an insoluble coating. Upon exposure to ultraviolet light, photocurable insulating resin materials undergo rapid physical and chemical changes, curing through crosslinking. Examples of photocurable insulating resin materials include, but are not limited to, polyurethane acrylates, epoxy acrylates, polyester acrylates, or polyether acrylates.

[0087] Ultraviolet light curing, also known as UV (UltraViolet Rays) curing, refers to the process of using the radiation energy of ultraviolet light to polymerize liquid photocurable insulating resin materials at high speed to form an insoluble solid coating. Ultraviolet light curing quickly hardens and dries in seconds, has a fast curing speed, high production efficiency, high energy utilization rate, does not require high temperature, saves energy, has low organic volatile components, is environmentally friendly, economical, and has wide adaptability. The wavelength of ultraviolet light used to excite ultraviolet light curing can be 300 nanometers to 450 nanometers, which can be selected according to actual needs and is not limited here; there is no special restriction on the intensity of ultraviolet light and it can be selected according to actual needs. The time of ultraviolet light irradiation can be 3 seconds to 30 seconds and can be selected according to actual needs and is not limited here.

[0088] By using photocurable insulating resin material as the insulating material and using ultraviolet light to irradiate the area of ​​the shell 22 sprayed with the insulating material, the insulating material can be quickly cured in a short time, greatly improving the production efficiency of the battery cell 20, being suitable for high-speed automated production, and being conducive to large-scale mass production of the battery cell 20. It is also energy-saving, environmentally friendly, economical and adaptable.

[0089] According to some embodiments of the present application, the photocurable insulating resin material includes a UV-curable coating. UV-curable coatings are coatings that are cured by ultraviolet radiation. The diluent in the UV-curable coating is not a volatile organic solvent, but a non-volatile solvent that directly participates in the curing and film-forming process and has the ability to react. After film formation, it becomes part of the coating. The solid content of UV-curable coatings can be as high as 100%, does not contain volatile organic compounds, and has little pollution to the environment. In addition, they have excellent physical properties, a fast curing speed, and good performance of the cured product. The high solid content enables UV-curable coatings to be applied to very thin coating films.

[0090] The outer surface of the shell 22 is coated with ultraviolet light-curing paint for insulation treatment. The appearance of the insulation layer is controllable and does not affect the assembly of the battery cell 20. The ultraviolet light-curing paint has strong bonding and adhesion and is not easy to fall off, which can greatly improve the insulation performance of the shell 22 and the insulation performance is stable.

[0091] According to other embodiments of the present application, the insulating material is a water-based paint or a solvent-based paint; and curing the area of ​​the housing 22 where the insulating material is sprayed comprises the following steps:

[0092] In step S320 , the battery cell 20 is baked to solidify the insulating material. The baking temperature is greater than 60 degrees Celsius (° C.) and less than 200° C.

[0093] Water-based paint refers to paint that uses water as a solvent or dispersion medium. Water-based paint offers excellent non-stick properties and durability, contains no organic solvents, is non-toxic and odorless, is harmless to the human body, and does not pollute the environment. It also offers excellent flexibility and is resistant to water, abrasion, aging, and yellowing, dries quickly, and is easy to use.

[0094] Solvent-based coatings are coatings made with organic solvents as the dispersion medium. They produce superior film quality and can achieve high-gloss coatings. They also have good environmental adaptability, making it easier to produce high-quality films. Solvent-based coatings also have a wide range of resins to choose from, with nearly all resins soluble in solvents. Different resins have their own unique properties, giving them a wide range of applications.

[0095] By electrostatically spraying water-based paint or solvent-based paint, the battery cell 20 is then subjected to a high-temperature baking treatment. Compared to batteries containing electrolytes that can only withstand baking at 60°C, the battery cell 20 without electrolyte is not injected and can withstand baking at a higher temperature. Specifically, the baking temperature is greater than 60°C and less than 200°C, so that the water-based paint or solvent-based paint is quickly dried and cured under the high-temperature aging process, forming an insulating layer on the outer surface of the shell 22.

[0096] In some embodiments, the baking temperature is greater than 100°C and less than 180°C.

[0097] By using water-based paint or solvent-based paint as the insulating material and performing high-temperature baking treatment on the battery cell 20, the insulating material can be quickly dried and solidified, and the production process can be selectively greatly expanded, significantly improving the coating performance, reducing the process time, greatly improving production efficiency, and reducing production costs. It is suitable for high-speed automated production and is conducive to large-scale mass production of battery cells 20.

[0098] According to some embodiments of the present application, after obtaining the battery cell 20 including the insulating layer and before injecting the electrolyte into the battery cell 20 including the insulating layer, the following steps are further included:

[0099] Step S301 : performing insulation testing on the housing 22 .

[0100] After the insulating material solidifies to form an insulating layer, the shell 22 is subjected to insulation testing to check whether the insulation performance of the shell 22 is qualified, such as whether there is a leakage short circuit problem, whether the breakdown voltage meets the requirements, etc.; the battery cells 20 that pass the test are transported to the electrolyte injection station for the next production step, and the battery cells 20 that fail the test can be recycled.

[0101] By testing the insulation performance of the shell 22 before injecting the electrolyte, the battery cells 20 whose insulation performance does not meet the requirements are identified and eliminated, so that the insulation performance of the battery cells 20 meets the product requirements, and the electrolyte injection of the battery cells 20 that do not meet the requirements is reduced, thereby reducing electrolyte waste, effectively saving materials, and reducing production costs.

[0102] According to some embodiments of the present application, before spraying the insulating material onto at least a portion of the outer surface of the housing 22 of the battery cell 20 by electrostatic spraying, the process further includes:

[0103] Step S101 : Cleaning the outer surface of the housing 22 .

[0104] By cleaning the outer surface of the shell 22, impurities such as dust, rust or stains on the outer surface of the shell 22 can be removed, which is beneficial to improving the adhesion between the insulation layer and the outer surface of the shell 22, making it less likely to fall off, further improving the quality of the insulation layer, and achieving better insulation performance and longer service life.

[0105] According to some embodiments of the present application, the cleaning process includes any one or more of sandblasting cleaning, plasma cleaning, and laser cleaning.

[0106] Sandblasting cleaning is the process of using a large amount of high-speed sand particles to impact a large area of ​​the outer surface of the shell 22 to remove dust, rust or stains on the outer surface of the shell 22, thereby achieving a cleaning function. In some embodiments, multiple sandblasting operations can also form a frosted surface on the outer surface after the rust or stains are removed. For example, a sandblasting head can be used to spray sand particles at least once onto the outer surface of the shell 22 to remove sand particles and stains on the outer surface; or the outer surface of the shell 22 can be placed in a negative pressure environment generated by the negative pressure port of a negative pressure dust collector, and a sandblasting head can be used to spray sand particles at least once onto the outer surface of the shell 22 to remove sand particles and stains on the outer surface. The number of sandblasting operations for sandblasting cleaning can be multiple, for example, two or three times.

[0107] Plasma cleaning utilizes a high-frequency voltage to generate a low-temperature plasma, which is sprayed onto the outer surface of the housing 22 to remove dust, rust, or stains adhering to the outer surface of the housing 22, thereby cleaning the outer surface of the housing 22. The low-temperature plasma has a relatively low temperature of 20°C to 30°C, so it cleans the outer surface of the housing 22 without burning it or forming an oxide layer on it, resulting in a good cleaning effect.

[0108] Laser cleaning utilizes a laser to emit point-shaped equidistant laser light to the outer surface of the shell 22. As the laser moves evenly relative to the outer surface of the shell 22, the outer surface of the shell 22 can be evenly irradiated by the laser, so that the entire outer surface of the shell 22 can be irradiated by the laser to the same degree. As the laser reconstructs the epidermis of the outer surface of the shell 22, the outer surface of the shell 22 can be evenly cleaned.

[0109] According to some embodiments of the present application, referring to FIG3 and further to FIG5 , FIG5 is a schematic diagram illustrating a method for measuring the thickness of an insulating layer 24 on a battery cell 20 in some embodiments of the present application. The present application provides a battery cell 20. The battery cell 20 is prepared according to the method for preparing a battery cell 20 in any of the above embodiments; the battery cell 20 includes a housing 22, a cell assembly 23, and an end cap 21. The insulating layer 24 is provided on at least a portion of the outer surface of the housing 22; the cell assembly 23 is accommodated in the housing 22; and the end cap 23 covers the opening of the housing 22.

[0110] Specifically, the thickness of the insulating layer 24 on the shell 22 can be measured using a film thickness tester. Referring to Figure 5, the film thickness tester includes a host (not shown) and a measuring probe 401. The measuring probe 401 is used to emit a detection signal. The host measures the thickness of the film layer covering the base material by detecting the received response signal. When measuring the thickness of the insulating layer 24 on the shell 22, the base material is the shell 22, and the film layer is the insulating layer 24; the measuring probe 401 is placed tightly against the insulating layer 24 of the shell 22. The measuring probe 401 emits a detection signal. The shell 22 can respond to the detection signal and feedback a response signal. The host measures the thickness of the insulating layer 24 based on the received response signal.

[0111] The use of the method for preparing the battery cell 20 in the above embodiment is beneficial to improving the safety performance of the battery cell 20 , extending its service life, increasing the coating utilization rate, and reducing production costs.

[0112] According to some embodiments of the present application, the film thickness tester includes handheld and desktop types, wherein the handheld film thickness tester includes one of a magnetic induction coating thickness gauge, an eddy current coating thickness gauge, and a fluorescent X-ray coating thickness gauge.

[0113] A magnetic induction coating thickness gauge uses the principle of magnetic induction to measure film thickness using the magnitude of the magnetic flux flowing from the measuring probe 401 through the non-ferromagnetic film layer and into the ferromagnetic substrate. It can also measure the magnetic resistance corresponding to the magnetic flux, indicating the film thickness. The thicker the film, the greater the magnetic resistance and the smaller the magnetic flux. This gauge has a resolution of 0.1 micron, a tolerance of 1%, and a measuring range of 10 mm. It can be used to accurately measure paint layers on steel surfaces, porcelain and enamel protective coatings, plastic and rubber coatings, various non-ferrous metal electroplating layers including nickel and chromium, and various anti-corrosion coatings in the chemical and petroleum industries. In this embodiment, the ferromagnetic substrate is the housing 22, and the film layer is the insulating layer 24.

[0114] An eddy current coating thickness gauge utilizes the eddy current principle. A high-frequency (above 1 MHz) AC coil generates an alternating magnetic field on the tip of the measuring probe 401. When the measuring probe 401 approaches the surface of a conductive substrate, the alternating magnetic field forms eddy currents on the surface. The closer the measuring probe 401 is to the conductive substrate, the greater the eddy currents and the greater the reflected impedance. This feedback action represents the distance between the measuring probe 401 and the conductive substrate, and therefore the thickness of the non-conductive coating on the conductive substrate. The eddy current coating thickness gauge has a resolution of 0.1 micron, an allowable error of 1%, and a measuring range of 10 mm. It is suitable for measuring the thickness of films on non-ferromagnetic metal substrates. It can be used to measure non-conductive coatings on all conductive surfaces, such as paint, plastic coatings, and anodized films on aerospace surfaces, vehicles, household appliances, aluminum alloy doors and windows, and other aluminum products. In this embodiment, the conductive substrate is the housing 22 , and the non-conductive coating is the insulating layer 24 .

[0115] According to some embodiments of the present application, a thickness H of the insulating layer 24 on the housing 22 is 80 micrometers to 200 micrometers.

[0116] The insulation performance of the insulation layer 24 refers to the dielectric strength and voltage breakdown resistance of the insulation layer 24 .

[0117] Dielectric strength is a measure of the electrical strength of a material as an insulator. It is defined as the maximum voltage per unit thickness that an insulator can withstand when it breaks down, expressed as volts per unit thickness. The greater the dielectric strength of an insulating material, the better it is as an insulator. The dielectric strength of insulating layer 24 is related to the insulating material used for insulating layer 24. When the same insulating material is used, the dielectric strength of insulating layer 24 remains constant.

[0118] Breakdown of the insulating layer 24 occurs when, under the action of a strong electric field, the insulating layer 24 loses its electrical insulation capability and suddenly changes from an insulating state to a highly conductive state. The lowest critical voltage that causes breakdown of the insulating layer 24 is the breakdown voltage of the insulating layer 24. The breakdown voltage of the insulating layer 24 is related to the dielectric strength and thickness of the insulating layer 24. For a given dielectric strength, a thicker insulating layer 24 has a higher breakdown voltage and better voltage breakdown resistance.

[0119] It can be seen that the thickness of the insulating layer 24 affects the insulation performance of the insulating layer 24, which in turn affects the safety performance and yield of the battery cell 20. In some cases, the thickness of the insulating layer 24 also affects the appearance and size of the battery cell 20, which in turn affects the subsequent assembly and material cost of the battery cell 20. In addition, the use of electrostatic spraying can achieve a more uniform insulating layer 24, which is conducive to reducing the thickness of the insulating layer 24 and improving the yield while improving the insulation performance of the insulating layer 24.

[0120] By setting the thickness H of the insulating layer 24 to 80 microns to 200 microns, the shell 22 has good insulation performance, which improves the safety performance of the battery cell 20. At the same time, by controlling the thickness of the insulating layer 24, the appearance and volume size of the battery cell 20 can be better controlled, which facilitates the subsequent assembly of the battery cell 20, improves production efficiency, and increases the yield rate, which is also beneficial to saving materials and reducing production costs.

[0121] According to some embodiments of the present application, the thickness H of the insulating layer 24 is 110 micrometers to 120 micrometers.

[0122] Further setting the thickness H of the insulating layer 24 to 110 μm to 120 μm is beneficial for better balancing the insulation performance of the shell 22 , the appearance volume and yield of the battery cell 20 , and reducing production costs, making it suitable for large-scale mass production.

[0123] Taking the insulating material of the insulating layer 24 as a light-curing insulating resin material as an example, the insulation performance and yield rate tests were conducted on the battery cells 20 with insulating layers 24 of different thicknesses. The test results are shown in Table 1 below.

[0124] Table 1 - Insulation performance and yield test results of battery cells 20 with different thicknesses of insulation layers 24

[0125] In Table 1, the unit of thickness H of insulating layer 24 is micrometer (μm); the unit of dielectric strength is kilovolt per millimeter (KV / mm); and the voltage breakdown performance is qualified when the leakage current is less than or equal to 0.1 milliampere (≤0.1mA) under a strong electric field of DC voltage 2700 volts (DC2700V), and failed when the leakage current is greater than 0.1 milliampere (>0.1mA).

[0126] It can be seen that when the thickness H of the insulating layer 24 is in the range of 80 microns to 200 microns, the battery cell 20 has good insulation performance, better controls the appearance and volume of the battery cell 20, and improves the yield; when the thickness H of the insulating layer 24 is in the range of 110 microns to 120 microns, the battery cell 20 can better take into account the insulation performance, appearance and volume, and yield, and is conducive to reducing production costs.

[0127] According to some embodiments of the present application, referring to FIG2 , the present application provides a battery 100 . The battery 100 includes a housing 10 and a battery cell 20 provided by the above embodiment. The battery cell 20 is accommodated in the housing 10 .

[0128] Since the battery 100 has the same technical effects as the battery cell 20 described above, detailed description thereof will be omitted here.

[0129] According to some embodiments of the present application, the present application further provides an electrical device, which includes the battery 100 or the battery cell 20 provided in the above embodiments, and the battery 100 and the battery cell 20 are used to provide electrical energy to the electrical device.

[0130] The power-consuming device may be any of the aforementioned devices or systems using the battery 100. Since the power-consuming device has the same technical effects as the aforementioned battery 100 and battery cell 20, a detailed description thereof will not be repeated here.

[0131] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A method for preparing a battery cell, wherein: The method for preparing the battery cell comprises: Make sure the battery cells are not charged; Spraying the insulating material onto at least a portion of the outer surface of the shell of the battery cell by electrostatic spraying; Performing a curing treatment on the area of ​​the shell on which the insulating material is sprayed to obtain a battery cell including an insulating layer; An electrolyte is injected into the battery cell including the insulating layer.

2. The method for preparing a battery monomer according to claim 1, wherein: The insulating material is a light-curing insulating resin material; The curing treatment of the area of ​​the shell sprayed with the insulating material comprises: The area of ​​the shell sprayed with the insulating material is irradiated with ultraviolet light to solidify the insulating material.

3. The method for preparing a battery monomer according to claim 2, wherein: The light-curable insulating resin material includes ultraviolet light-curable coating.

4. The method for preparing a battery monomer according to claim 2, wherein: The UV light irradiation time is 3 seconds to 30 seconds.

5. The method for preparing a battery monomer according to claim 1, wherein: The insulating material is a water-based paint or a solvent-based paint; The curing treatment of the area of ​​the shell sprayed with the insulating material comprises: The battery cell is baked to solidify the insulating material; wherein the baking temperature is greater than 60° C. and less than 200° C.

6. The method for preparing a battery monomer according to claim 5, wherein: The baking temperature is greater than 100°C and less than 180°C.

7. The method for preparing a battery monomer according to any one of claims 1 to 6, wherein: After obtaining the battery cell including the insulating layer and before injecting the electrolyte into the battery cell including the insulating layer, the method further includes: An insulation test is performed on the housing.

8. The method for preparing a battery monomer according to any one of claims 1 to 6, wherein: Before the insulating material is sprayed onto at least a portion of the outer surface of the shell of the battery cell by electrostatic spraying, the method further includes: The outer surface of the shell is cleaned.

9. The method for preparing a battery monomer according to claim 8, wherein: The cleaning process includes any one or more of sandblasting cleaning, plasma cleaning and laser cleaning.

10. The method for preparing a battery monomer according to any one of claims 1 to 6, wherein: Determining that the battery cell is in an uncharged state includes: winding or stacking the positive electrode sheet, the negative electrode sheet and the separator to form a battery cell assembly, placing the battery cell assembly into a shell, and then covering and welding the end cover to the opening of the shell to obtain a battery cell without electrolyte.

11. A battery cell, wherein: The battery monomer is prepared according to the method for preparing a battery monomer according to any one of claims 1 to 10; the battery monomer comprises: A shell, wherein an insulating layer is provided on at least a portion of an outer surface of the shell; A battery cell assembly, the battery cell assembly being accommodated in the housing; and An end cover is covered on the opening of the shell.

12. The battery cell according to claim 11, wherein: The thickness of the insulating layer on the shell is 80 micrometers to 200 micrometers.

13. The battery cell according to claim 12, wherein: The thickness of the insulating layer is 110 micrometers to 120 micrometers.

14. A battery, wherein: The battery comprises the battery cell according to any one of claims 11 to 13.

15. An electrical device, wherein: The electrical device comprises the battery according to claim 14 or the battery cell according to any one of claims 11 to 13, and the battery and the battery cell are used to provide electrical energy.

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