Battery monomer and preparation method thereof, battery and power utilization device

Abstract

The invention relates to a battery monomer, a preparation method thereof, a battery and a power utilization device. The preparation method of the battery monomer comprises the following steps: determining that the battery monomer is in an uncharged state; spraying an insulating material on at least one part of the area of the outer surface of the shell of the battery monomer in an electrostatic spraying manner; carrying out curing treatment on the region, sprayed with the insulating material, of the shell to obtain a battery monomer containing an insulating layer; and injecting an electrolyte into the battery cell containing the insulating layer. According to the preparation method of the battery monomer, insulation spraying is performed when the battery monomer is in the uncharged state, and the insulation spraying can be performed by adopting electrostatic spraying, so that the coating utilization rate of a battery shell insulation layer in a battery production process can be improved, and the production cost is reduced.

Description

Technical Field

[0001] This application relates to the technical field of batteries, and particularly to a battery cell, a preparation method thereof, a battery, and an electrical device. Background Art

[0002] As an important component of new energy vehicles, the service life and safety performance of power batteries are extremely important. The service life and safety performance of batteries are not only affected by electrode materials, but also by the structure and insulation performance of the battery housing. To prevent safety problems such as scratches or short circuits on the surface of the battery housing, an insulating layer is usually provided on the outer surface of the battery housing.

[0003] In related technologies, an insulating material is usually coated on the surface of the battery housing by spraying. How to improve the coating utilization rate of the insulating layer of the battery housing in the battery production process has become an urgent problem to be solved. Summary of the Invention

[0004] In view of the above problems, this application provides a battery cell, a preparation method thereof, a battery, and an electrical device, which can improve the coating utilization rate of the insulating layer of the battery housing in the battery production process.

[0005] In a first aspect, this application provides a preparation method of a battery cell, and the preparation method of the battery cell includes:

[0006] Determine that the battery cell is in a non-charged state;

[0007] Spray an insulating material onto at least a part of the outer surface of the housing of the battery cell by electrostatic spraying;

[0008] Cure the area of the housing sprayed with the insulating material to obtain a battery cell including an insulating layer;

[0009] Inject electrolyte into the battery cell including the insulating layer.

[0010] In the technical solution of the embodiment of this application, by performing insulating spraying when the battery cell is in a non-charged state, electrostatic spraying can be used for insulating spraying, which can improve the coating utilization rate of the insulating layer of the battery housing in the battery production process, reduce production costs, simplify the spraying process, improve production efficiency, and the insulating layer formed by electrostatic spraying has higher quality, which is beneficial to maintaining the uniformity of the insulating performance of the insulating layer, has better insulating performance, longer service life, and improves the safety performance of the battery cell.

[0011] In some embodiments, the insulating material is a photocurable insulating resin material;

[0012] The curing treatment of the area of the housing sprayed with the insulating material includes:

[0013] Irradiate the area of the housing sprayed with the insulating material with ultraviolet light to cure the insulating material.

[0014] With such a setting, the insulating material can be quickly cured in a short time, greatly improving the production efficiency of the battery cell, facilitating the large-scale mass production of the battery cell, and being energy-saving, environmentally friendly, highly economical and adaptable.

[0015] In some embodiments, the insulating material is a water-based paint or a solvent-based paint;

[0016] The curing treatment of the area of the housing sprayed with the insulating material includes:

[0017] Bake the battery cell to cure the insulating material; wherein, the baking temperature is greater than 60°C and less than 200°C.

[0018] With such a setting, the insulating material can be quickly dried and cured, and the production process options can be significantly expanded, significantly improving the coating performance, reducing the process time-consuming, greatly improving the production efficiency, reducing the production cost, being suitable for high-speed automated production, and facilitating the large-scale mass production of the battery cell.

[0019] In some embodiments, after obtaining the battery cell including the insulating layer and before injecting the electrolyte into the battery cell including the insulating layer, it further includes:

[0020] Perform an insulation detection on the housing.

[0021] By detecting the insulation performance of the housing before injecting the electrolyte, identify and eliminate the battery cells whose insulation performance does not meet the requirements, effectively ensuring that the insulation performance meets the product requirements, and avoiding injecting electrolyte into the battery cells that do not meet the requirements, preventing electrolyte waste, effectively saving materials, and reducing the production cost.

[0022] In some embodiments, before spraying the insulating material on at least a part of the outer surface of the housing of the battery cell by means of electrostatic spraying, it further includes:

[0023] Clean the outer surface of the housing.

[0024] By cleaning the outer surface of the housing, impurities such as floating dust, rust or stains on the outer surface of the housing can be removed, which is beneficial to improving the adhesion between the insulating layer and the outer surface of the housing, making it not easy to fall off, further improving the quality of the insulating layer, having better insulation performance and longer service life.

[0025] In a second aspect, the present application provides a battery cell, which is prepared according to the preparation method of the battery cell in any of the above embodiments; the battery cell includes:

[0026] A housing, at least a part of the outer surface of the housing is provided with an insulating layer;

[0027] A battery cell assembly, the battery cell assembly is accommodated in the housing; and

[0028] An end cap, the end cap covers the opening of the housing.

[0029] In some embodiments, the thickness of the insulating layer on the housing is 80 microns to 200 microns. With such a setting, the housing has good insulation performance, ensuring the safety performance of the battery cell. At the same time, by controlling the thickness of the insulating layer, the appearance and volume dimensions of the battery cell can be better controlled, facilitating the subsequent assembly of the battery cell, improving production efficiency, ensuring a high yield rate, and also being beneficial to saving materials and reducing production costs.

[0030] In some embodiments, the thickness of the insulating layer is 110 microns to 120 microns. With such a setting, it is beneficial to better balance the insulation performance of the housing, the appearance and volume of the battery cell, and the yield rate, and reduce production costs, which is suitable for large-scale mass production.

[0031] In a third aspect, the present application provides a battery, the battery includes the battery cell in any of the above embodiments.

[0032] In a fourth aspect, the present application provides an electrical device, the electrical device includes the battery in the above embodiments or the battery cell in any of the above embodiments, and the battery and the battery cell are used to provide electrical energy.

[0033] The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present application more obvious and understandable, the following specifically describes the specific embodiments of the present application. Description of the Drawings

[0034] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present application. And in all the drawings, the same reference numerals are used to represent the same components.

[0035] In the drawings:

[0036] Figure 1 is a schematic structural diagram of a vehicle in some embodiments of the present application.

[0037] Figure 2 is an exploded structural diagram of a battery in some embodiments of the present application.

[0038] Figure 3 Schematic diagram of the disassembly structure of a battery cell according to some embodiments of the present application.

[0039] Figure 4 Schematic flow chart of the preparation method of a battery cell according to some embodiments of the present application.

[0040] Figure 5 Schematic diagram of the method for measuring the thickness of the insulating layer on a battery cell according to some embodiments of the present application.

[0041] The reference numerals in the specific embodiments are as follows:

[0042] 1000, vehicle;

[0043] 100, battery; 200, controller; 300, motor;

[0044] 10, box body; 11, first part; 12, second part;

[0045] 20, battery cell; 21, end cap; 21a, electrode terminal; 22, housing; 23, cell assembly; 23a, tab; 24, insulating layer;

[0046] 401, measuring probe. Specific embodiments

[0047] To make the above objects, features, and advantages of the present application more apparent and understandable, the following will describe the specific embodiments of the present application in detail with reference to the accompanying drawings. Many specific details are set forth in the following description in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0048] Referring to "embodiments" herein means that specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion.

[0050] In the description of the embodiments of the present application, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation on the present application.

[0051] In the description of the embodiments of the present application, the terms "first" and "second" are only used for descriptive purposes to distinguish different objects, and should not be construed as indicating or implying relative importance or implicitly specifying the quantity, specific order or primary-secondary relationship of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the embodiments of the present application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0052] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0053] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, the terms "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0054] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may mean that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "below" and "beneath" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the horizontal height of the first feature is less than that of the second feature.

[0055] It should be noted that an element is referred to as being "fixed to" or "disposed on" another element, and it may be directly on the other element or there may also be an intermediate element. An element is considered to be "connected to" another element, and it may be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in the present application are only for the purpose of illustration and do not represent the only implementation manner.

[0056] At present, from the perspective of the development of the market situation, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles and electric vehicles, as well as in many fields such as military equipment and aerospace. With the continuous expansion of the application fields of power batteries, the market demand is also constantly increasing.

[0057] As an important part of new energy vehicles, the service life and safety performance of power batteries are extremely important. The service life and safety performance of the battery are not only affected by the electrode materials, but also affected by the battery housing structure and insulation performance. In order to prevent safety problems such as scratches or short circuits on the surface of the battery housing, an insulating layer is generally provided on the outer surface of the battery housing.

[0058] In the related art, usually, a battery cell is formed by assembling a positive electrode sheet, a negative electrode sheet, a separator and a housing without an insulating layer, and then an electrolyte is injected into the battery cell to obtain an assembled battery; then, an insulating spray is performed on the outer surface of the assembled battery, and after curing treatment, an assembled battery including an insulating layer is obtained. Among them, since an insulating spray is performed on the assembled battery containing the electrolyte, and the assembled battery containing the electrolyte is charged, for safety considerations, only air spraying can be used for the insulating spray at this time, and electrostatic spraying cannot be used. However, the paint utilization rate of air spraying is relatively low, resulting in material waste and high production costs.

[0059] To improve the paint utilization rate and reduce the production cost, an electrostatic powder can be first sprayed on the outer surface of the housing to form an insulating layer. Then, components such as the positive electrode plate, negative electrode plate, and separator are assembled into the housing. Next, the top cover is welded to the housing. Finally, an electrolyte is injected into the housing to obtain an assembled battery. However, when spraying the battery housing first, positions for electrode plate welding need to be reserved, the spraying process is complex, and the unsprayed positions need subsequent steps of winding insulating tape, increasing the process steps and reducing the production efficiency. Moreover, since welding sparks are generated during the welding process and the temperature of the welding sparks is very high, it is easy to ablate the insulating layer and form multiple tiny dot-like depressions on the surface of the insulating layer. These depressions not only affect the surface flatness of the insulating layer but also the uniformity of the insulating performance of the entire insulating layer.

[0060] Based on the above considerations, in order to improve the paint utilization rate of the insulating layer of the battery housing in the battery production process, a method for preparing a battery cell is designed. The process sequence of the electrolyte injection process and the insulating spraying process in the battery production process is adjusted. That is, after assembling the positive electrode plate, negative electrode plate, separator, and a housing without an insulating layer to form an electric core, the electrolyte injection process is not carried out temporarily, so as to obtain a battery cell without electrolyte. Since the battery cell without electrolyte is not charged, electrostatic spraying can be used for insulating spraying at this time. After the spraying and curing are completed, the electrolyte is injected to obtain a battery cell containing electrolyte. Thereby, the paint utilization rate of the insulating layer of the battery housing in the battery production process can be improved.

[0061] The method for preparing a battery cell disclosed in the embodiments of the present application is used for preparing a battery cell. In this way, it is beneficial to improve the paint utilization rate, reduce the production cost, simplify the spraying process, improve the production efficiency, and ensure the uniformity of the insulating performance of the insulating layer.

[0062] The battery cell disclosed in the embodiments of the present application can be but is not limited to being used in power-consuming devices such as vehicles, ships, or aircraft. A power supply system of the power-consuming device can be composed of the battery cell and battery disclosed in the present application. In this way, it is beneficial to reduce the cost and ensure the insulating performance.

[0063] The embodiments of the present application provide a power-consuming device using a battery as a power source. The power-consuming device can be but is not limited to mobile phones, tablets, laptop computers, electric toys, electric tools, battery cars, electric vehicles, ships, spacecraft, etc. Among them, the electric toy can include fixed or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys, and electric aircraft toys, etc. The spacecraft can include airplanes, rockets, space shuttles, and spaceships, etc.

[0064] For the convenience of description in the following embodiments, a power-consuming device of some embodiments of the present application, a vehicle 1000, is taken as an example for illustration.

[0065] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of a vehicle 1000 provided for 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, an extended-range vehicle, etc. A battery 100 is disposed inside the vehicle 1000. The battery 100 can be disposed at the bottom, the head, or the tail of the vehicle 1000. The battery 100 can be used to supply power to the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 can further include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to supply power to the motor 300. For example, it is used for the working power requirements during the start, navigation, and driving of the vehicle 1000.

[0066] In some embodiments of the present application, the battery 100 can not only serve as an operating power source for the vehicle 1000, but also serve 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.

[0067] Please refer to Figure 2 , Figure 2 which is an exploded view of the battery 100 provided for some embodiments of the present application. The battery 100 includes a box body 10 and battery cells 20. The battery cells 20 are accommodated in the box body 10. Among them, the box body 10 is used to provide an accommodation space for the battery cells 20, and the box body 10 can adopt various structures. In some embodiments, the box body 10 can include a first part 11 and a second part 12. The first part 11 and the second part 12 cover each other, and the first part 11 and the second part 12 jointly define an accommodation space for accommodating the battery cells 20. The second part 12 can be a hollow structure with one end open, and the first part 11 can be a plate-like structure. The first part 11 covers the open side of the second part 12 so that the first part 11 and the second part 12 jointly define an accommodation space; the first part 11 and the second part 12 can also both be hollow structures with one side open, and the open side of the first part 11 covers the open side of the second part 12. Of course, the box body 10 formed by the first part 11 and the second part 12 can be of various shapes, such as a cylinder, a cuboid, etc.

[0068] In battery 100, there may be multiple battery cells 20. The multiple battery cells 20 can be connected in series, parallel, or in a combined series-parallel connection. A combined series-parallel connection means that there are both series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 can be directly connected in series, parallel, or in a combined series-parallel connection and then the whole formed by the multiple battery cells 20 is accommodated in the box 10. Of course, the battery 100 can also be such that multiple battery cells 20 are first connected in series, parallel, or in a combined series-parallel connection to form a battery module, and then multiple battery modules are connected in series, parallel, or in a combined series-parallel connection to form a whole and are accommodated in the box 10. The battery 100 can also include other structures. For example, the battery 100 can also include a busbar component for realizing the electrical connection among the multiple battery cells 20.

[0069] Among them, 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 in the shape of a cylinder, a flat body, a cuboid, or other shapes, that is, the battery cell 20 is not limited to a square-shell battery and can also be a cylindrical battery, etc.

[0070] Please refer to Figure 3 , Figure 3 which is a schematic exploded view of the battery cell 20 provided in some embodiments of the present application. The battery cell 20 refers to the smallest unit that makes up the battery. As Figure 3 shown, the battery cell 20 includes an end cap 21, a housing 22, a core component 23, and other functional components.

[0071] The end cap 21 refers to a component that covers the opening of the housing 22 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 21 can be adapted to the shape of the housing 22 to cooperate with the housing 22. Optionally, the end cap 21 can be made of a material with a certain hardness and strength (such as aluminum alloy). In this way, the end cap 21 is not easily deformed when being squeezed or collided, enabling the battery cell 20 to have higher structural strength and also improving the safety performance. Functional components such as electrode terminals 21a can be provided on the end cap 21. The electrode terminals 21a can be used for electrically connecting with the core component 23 to output or input the electric energy of the battery cell 20. In some embodiments, a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold can also be provided on the end cap 21. The material of the end cap 21 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. The embodiments of the present application do not make special limitations thereto. In some embodiments, an insulating member can also be provided on the inner side of the end cap 21. The insulating member can be used to isolate the electrical connection components in the housing 22 from the end cap 21 to reduce the risk of short circuit. Exemplarily, the insulating member can be plastic, rubber, etc.

[0072] The housing 22 is a component for cooperating with the end cap 21 to form the internal environment of the battery cell 20. Among them, the formed internal environment can be used to accommodate the battery cell assembly 23, the electrolyte, and other components. The housing 22 and the end cap 21 can be independent components. An opening can be provided on the housing 22, and the end cap 21 is covered at the opening to form the internal environment of the battery cell 20. Without limitation, the end cap 21 and the housing 22 can also be integrated. Specifically, the end cap 21 and the housing 22 can first form a common connection surface before other components are put into the housing. When it is necessary to encapsulate the inside of the housing 22, the end cap 21 is then covered on the housing 22. The housing 22 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 22 can be determined according to the specific shape and size of the battery cell assembly 23. The material of the housing 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. The embodiments of the present application do not make special restrictions on this.

[0073] The battery cell assembly 23 is a component in the battery cell 20 where an electrochemical reaction occurs. The housing 22 can contain one or more battery cell assemblies 23. The battery cell assembly 23 is mainly formed by winding or laminating a positive electrode sheet and a negative electrode sheet, and a separator is usually provided between the positive electrode sheet and the negative electrode sheet. The parts of the positive electrode sheet and the negative electrode sheet with active substances constitute the main body of the battery cell assembly 23, and the parts of the positive electrode sheet and the negative electrode sheet without active substances respectively constitute the electrode tabs 23a. The positive electrode tab and the negative electrode tab can be located at one end of the main body together or at both ends of the main body respectively. During the charge and discharge process of the battery, the positive electrode active substance and the negative electrode active substance react with the electrolyte, and the electrode tab 23a is connected to the electrode terminal 21a to form an electric current loop.

[0074] According to some embodiments of the present application, refer to Figure 3 and please further refer to Figure 4 Figure 4 shows a schematic flow chart of the preparation method of the battery cell 20 in some embodiments of the present application. The present application provides a preparation method of the battery cell 20. The preparation method of the battery cell 20 includes the following steps:

[0075] Step S100, determine that the battery cell 20 is in a non-charged state;

[0076] Step S200, spray an insulating material on at least a part of the outer surface of the housing 22 of the battery cell 20 by means of electrostatic spraying;

[0077] Step S300, perform a curing treatment on the area of the housing 22 sprayed with the insulating material to obtain the battery cell 20 including an insulating layer;

[0078] Step S400, inject an electrolyte into the battery cell 20 including the insulating layer.

[0079] 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 without the coated positive electrode active material layer protrudes from the positive electrode current collector with the coated positive electrode active material layer. The positive electrode current collector without the coated positive electrode active material layer forms the positive electrode tab. Taking a lithium-ion battery as an example, the positive electrode current collector can be aluminum foil, and the positive electrode active material can be lithium cobaltate, lithium iron phosphate, ternary lithium, lithium manganate, etc. After stirring and mixing the positive electrode active material, etc., a positive electrode slurry is obtained. Then, the positive electrode slurry is coated on the surface of the positive electrode current collector, and after baking and drying, through processes such as cold pressing (rolling), pre-slitting, and slitting, the positive electrode sheet is prepared.

[0080] The negative electrode sheet includes 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 without the coated negative electrode active material layer protrudes from the negative electrode current collector with the coated negative electrode active material layer. The negative electrode current collector without the coated 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 or silicon, etc. After stirring and mixing the negative electrode active material, etc., a negative electrode slurry is obtained. Then, the negative electrode slurry is coated on the surface of the negative electrode current collector, and after baking and drying, through processes such as cold pressing, pre-slitting, and slitting, the negative electrode sheet is prepared.

[0081] The separator can be at least one of a glass fiber cloth, a non-woven fabric, a polypropylene (PP) film, and a polyethylene (PE) film; the separator can be a single-layer film or a multi-layer composite film, and there is no limitation here.

[0082] It is determined 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 housing 22 without an insulating layer together, the electrolyte injection process is not carried out temporarily, so as to obtain a battery cell 20 without electrolyte. Since there is no 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 laminated to form a battery core assembly 23, the battery core assembly 23 is installed in the housing 22, and then the end cap 21 is covered and welded at the opening of the housing 22 to obtain a battery cell 20 without electrolyte. In other embodiments, the battery cell 20 can contain a small amount of electrolyte or a solid electrolyte, but is in an uncharged state.

[0083] Insulating materials refer to substances that do not conduct electricity or conduct electricity very slightly under the action of a DC voltage. Electrostatic spraying refers to a coating method in which atomized paint is negatively charged under the action of a high-voltage DC electric field by using the principle of corona discharge and is adsorbed on the surface of the positively charged object to be coated for discharging. In electrostatic spraying, there is basically no phenomenon of paint jet rebound and paint mist scattering, and the loss of paint mist is very small. Therefore, the paint utilization rate is high, reaching 85% or more. And due to the action of the high-voltage electrostatic field, the paint particles have a high degree of dispersion and are also relatively evenly distributed in the jet. Therefore, the coating formed on the surface of the object to be coated is relatively flat and uniform, and the gloss and adhesion of the paint film are relatively high. At the same time, the spraying efficiency is relatively high. In this application, the object to be coated is the housing 22 of the battery cell 20. Since the battery cell 20 is in an uncharged state, the insulating material can be sprayed on at least a part of the outer surface of the housing 22 by means of electrostatic spraying, so as to achieve the purpose of improving the paint utilization rate, reducing the production cost, with a simple process and higher production efficiency. And the insulating layer formed by electrostatic spraying has a higher quality, better insulating performance, higher adhesion between the insulating layer and the housing 22, stronger environmental tolerance and longer service life. This application has no special restrictions on the process parameters such as spraying distance, time, voltage, and flow rate of electrostatic spraying, and can be selected according to actual needs.

[0084] The curing treatment of the area of the housing 22 sprayed with the insulating material refers to the process of drying the film by converting the substances in the insulating material from low molecules to high molecules. After the insulating material coated on the outer surface of the housing 22 undergoes the curing treatment, an insulating layer is formed on the outer surface of the housing 22, so as to obtain the battery cell 20 including the insulating layer, for insulating the metal housing 22 of the battery cell 20, effectively preventing safety problems such as scratching or short circuit on the outer surface of the housing 22 of the battery cell 20, and improving the safety of the battery cell 20.

[0085] After the curing of the insulating layer to be sprayed is completed, electrolyte is injected into the battery cell 20 including the insulating layer to obtain the battery cell 20 containing the electrolyte. Specifically, after injecting the electrolyte, it also goes through processes such as vacuum packaging, formation, and laser welding of the sealing nail, so as to obtain the battery cell 20. During the charge and discharge process of the battery cell 20, active ions are embedded and removed back and forth between the positive electrode plate and the negative electrode plate, and the electrolyte plays a role in conducting active ions between the positive electrode plate and the negative electrode plate. This application has no special restrictions on the type of electrolyte and can be selected according to actual needs.

[0086] The preparation method of the battery cell 20 according to the embodiment of the present application adjusts the process sequence of the electrolyte injection process and the insulation spraying process during the production of the battery cell 20. Insulation spraying is carried out 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 case 22 in the battery production process, reduce the production cost, simplify the spraying process, improve the production efficiency, and the insulation layer formed by electrostatic spraying has higher quality, which is beneficial to maintaining the uniformity of the insulation performance of the insulation layer, has better insulation performance, longer service life, and improves the safety performance of the battery cell 20.

[0087] According to some embodiments of the present application, the insulating material is a photocurable insulating resin material; the area of the housing 22 sprayed with the insulating material is cured, including the following steps:

[0088] Step S310, irradiate the area of the housing 22 sprayed with the insulating material with ultraviolet light to cure the insulating material.

[0089] The photocurable insulating resin material refers to a resin material composed of resin monomers and prepolymers, containing active functional groups, and can undergo a polymerization reaction initiated by a photosensitizer under ultraviolet light irradiation to form an insoluble coating film. After being irradiated by ultraviolet light, the photocurable insulating resin material can rapidly undergo physical and chemical changes and crosslink and cure in a short time. The photocurable insulating resin material includes one or more of polyurethane acrylate, epoxy acrylate, polyester acrylate, or polyether acrylate, etc., and is not limited here.

[0090] Ultraviolet curing, that is, UV (UltraViolet Rays, namely ultraviolet light) curing, refers to the process of using the radiation energy of ultraviolet light to rapidly polymerize a liquid photocurable insulating resin material to form an insoluble solid coating film. Ultraviolet curing hardens and dries rapidly in seconds, has a fast curing speed, high production efficiency, high energy utilization rate, does not require high temperature, saves energy, has less volatile organic components, is environmentally friendly, economical, and has wide adaptability. The wavelength of the ultraviolet light used to stimulate ultraviolet curing can be 300 nanometers to 450 nanometers, which can be selected according to actual needs and is not limited here; the light intensity of the ultraviolet light has no special limitation and can be selected according to actual needs. The ultraviolet curing time can be 3 seconds to 30 seconds, which can be selected according to actual needs and is not limited here.

[0091] By using the photocurable insulating resin material as the insulating material and irradiating the area of the housing 22 sprayed with the insulating material with ultraviolet light, the insulating material can be rapidly cured in a short time, greatly improving the production efficiency of the battery cell 20, being suitable for high-speed automated production, being beneficial to the large-scale mass production of the battery cell 20, and being energy-saving and environmentally friendly, with high economy and adaptability.

[0092] According to some embodiments of the present application, the photo-curable insulating resin material includes an ultraviolet (UV)-curable coating. The UV-curable coating is a coating cured by UV radiation. The diluent in the UV-curable coating is not a volatile organic solvent, but a non-volatile solvent that directly participates in the film-forming process and has reactivity, and becomes part of the coating film after film formation. The solid content of the UV-curable coating can be as high as 100%, does not contain volatile organic compounds, has little environmental pollution, excellent physical properties, fast curing speed, good properties of the cured product, and the high solid content enables the UV-curable coating to be also applied to very thin coating films.

[0093] By using the UV-curable coating to coat the outer surface of the housing 22 for insulation treatment, the appearance of the insulating layer is controllable and does not affect the assembly of the battery cell 20. The UV-curable coating has strong adhesion and cohesion, is not easy to fall off, can greatly improve the insulation performance of the housing 22, and the insulation performance is stable.

[0094] According to some other embodiments of the present application, the insulating material is a water-based coating or a solvent-based coating; the area of the housing 22 sprayed with the insulating material is cured, including the following steps:

[0095] Step S320, baking the battery cell 20 to cure the insulating material; wherein, the baking temperature is greater than 60°C and less than 200°C.

[0096] A water-based coating refers to a coating using water as a solvent or a dispersion medium. The water-based coating has excellent non-stickiness and durability, does not contain organic solvents, is non-toxic, odorless, harmless to the human body, does not pollute the environment, has good flexibility, and has characteristics such as water resistance, abrasion resistance, aging resistance, yellowing resistance, fast drying, and easy use.

[0097] A solvent-based coating refers to a coating prepared with an organic solvent as a dispersion medium. The coating film of the solvent-based coating has better quality and can achieve a high-gloss coating; the solvent-based coating has good environmental adaptability and is easy to obtain a high-quality coating film; the solvent-based coating has a wide range of resin selection, and almost all resins can be dissolved in the solvent, and different resins have their own unique properties, so the solvent-based coating has a wide range of applications.

[0098] By electrostatically spraying the water-based coating or the solvent-based coating and then performing a high-temperature baking treatment on the battery cell 20, compared with a battery containing an electrolyte that can only withstand baking at 60°C, the battery cell 20 without electrolyte injection at this time 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 coating or the solvent-based coating can be quickly dried and cured under the high-temperature aging process to form an insulating layer on the outer surface of the housing 22.

[0099] In some embodiments, the baking temperature is greater than 100 °C and less than 180 °C.

[0100] By using an aqueous coating or a solvent-based coating as the insulating material and subjecting the battery cell 20 to high-temperature baking treatment, the insulating material can be quickly dried and cured, and the production process options can be significantly expanded, significantly improving the coating performance, reducing the process time consumption, greatly improving the production efficiency, and reducing the production cost, which is suitable for high-speed automated production and is conducive to the large-scale mass production of the battery cell 20.

[0101] 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:

[0102] Step S301, perform an insulation detection on the housing 22.

[0103] After the insulating material is cured to form the insulating layer, an insulation detection is performed on the housing 22 to detect whether the insulation performance of the housing 22 is qualified, such as detecting whether there is a leakage short circuit problem, whether the breakdown voltage withstand meets the requirements, etc.; the qualified battery cells 20 are transported to the electrolyte injection station for the next production step, and the unqualified battery cells 20 can be recycled.

[0104] By detecting the insulation performance of the housing 22 before injecting the electrolyte, the battery cells 20 with unsatisfactory insulation performance are identified and removed, effectively ensuring that the insulation performance of the battery cells 20 meets the product requirements, and avoiding injecting the electrolyte into the battery cells 20 that do not meet the requirements, preventing electrolyte waste, effectively saving materials, and reducing the production cost.

[0105] According to some embodiments of the present application, before spraying the insulating material on at least a part of the outer surface of the housing 22 of the battery cell 20 by means of electrostatic spraying, the following is further included:

[0106] Step S101, perform a cleaning treatment on the outer surface of the housing 22.

[0107] By performing a cleaning treatment on the outer surface of the housing 22, impurities such as floating dust, rust or stains on the outer surface of the housing 22 can be removed, which is beneficial to improving the adhesion between the insulating layer and the outer surface of the housing 22, making it not easy to fall off, further improving the quality of the insulating layer, having better insulation performance and longer service life.

[0108] According to some embodiments of the present application, the cleaning treatment includes any one or several of sandblasting cleaning, plasma cleaning, and laser cleaning.

[0109] Sandblasting cleaning utilizes a large number of high-speed moving sand grains to impact a large area of the outer surface of the housing 22, so as to remove floating dust, rust or stains adhered to the outer surface of the housing 22, thereby realizing the cleaning function. In addition, through multiple sandblasting, a matte surface can also be formed on the outer surface after removing rust or stains. Specifically, a sandblasting head can be used to spray sand grains on the outer surface of the housing 22 at least once to remove the sand grains and stains on the outer surface; alternatively, the outer surface of the housing 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 grains on the outer surface of the housing 22 at least once, thereby removing the sand grains and stains on the outer surface. The number of sandblasting times for sandblasting cleaning can be multiple, such as two or three times, etc.

[0110] Plasma cleaning utilizes low-temperature plasma excited by a high-frequency voltage to be sprayed onto the outer surface of the housing 22, so as to remove floating dust, rust or stains adhered to the outer surface of the housing 22, thereby realizing the cleaning of the outer surface of the housing 22. The temperature of the low-temperature plasma is relatively low, ranging from 20°C to 30°C. Therefore, while cleaning the outer surface of the housing 22, it will not burn out the outer surface of the housing 22 or form an oxide layer on the outer surface of the housing 22, and the cleaning effect is good.

[0111] Laser cleaning utilizes a laser to emit dot-shaped equidistant lasers onto the outer surface of the housing 22. As the laser moves uniformly relative to the outer surface of the housing 22, the outer surface of the housing 22 can be uniformly irradiated by the laser, so that the entire outer surface of the housing 22 can be irradiated by the laser to the same extent. As the laser reconstructs the outer skin of the housing 22, the uniform cleaning of the outer surface of the housing 22 is realized.

[0112] According to some embodiments of the present application, with reference to Figure 3 and please further refer to Figure 5 , Figure 5 shows a schematic diagram of a method for measuring the thickness of the insulating layer 24 on the 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 preparation method of the battery cell 20 in any of the above embodiments; the battery cell 20 includes a housing 22, a battery core assembly 23 and an end cover 21, and an insulating layer 24 is provided on at least a part of the outer surface of the housing 22; the battery core assembly 23 is accommodated in the housing 22; the end cover 23 is covered at the opening of the housing 22.

[0113] Specifically, the thickness of the insulating layer 24 on the housing 22 can be measured by a film thickness tester. With reference to Figure 5, the film thickness tester includes a main body (not shown in the figure) and a measuring probe 401. The measuring probe 401 is used to emit a detection signal, and the main body measures the film thickness of the film layer covering the substrate material by detecting the received response signal. When measuring the thickness of the insulating layer 24 on the measuring housing 22, the substrate material is the housing 22 and the film layer is the insulating layer 24; the measuring probe 401 is closely attached to the insulating layer 24 of the housing 22, the measuring probe 401 emits a detection signal, the housing 22 can respond to the detection signal and feedback the response signal, and the main body measures the thickness of the insulating layer 24 according to the received response signal.

[0114] Due to the preparation method of the battery cell 20 in the above embodiment, it is beneficial to improve the safety performance of the battery cell 20, with a longer service life, and also improve the coating utilization rate and reduce the production cost.

[0115] According to some embodiments of the present application, the film thickness tester includes a handheld type and a desktop type. 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.

[0116] The magnetic induction coating thickness gauge refers to a thickness gauge that uses the magnetic induction principle and measures the film thickness by the magnitude of the magnetic flux flowing from the measuring probe 401 through the non-ferromagnetic film layer into the ferromagnetic substrate; it can also measure the magnitude of the magnetic resistance corresponding to the magnetic flux, indicating the film thickness. The thicker the film layer, the greater the magnetic resistance and the smaller the magnetic flux. The resolution of the magnetic induction coating thickness gauge reaches 0.1 micron, the allowable error reaches 1%, and the measuring range reaches 10 mm. The magnetic induction coating thickness gauge can be used to accurately measure paint layers on the surface of steel, porcelain and enamel protective layers, plastic and rubber coatings, various non-ferrous metal electroplating layers including nickel-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.

[0117] The eddy current coating thickness gauge is a thickness gauge that uses the eddy current principle; a high-frequency (frequency above 1 MHz) alternating current coil is used to generate an alternating magnetic field on the head surface of the measuring probe 401. When the measuring probe 401 is close to the surface of the conductive substrate, an eddy current is formed on the surface of the conductive substrate by the alternating magnetic field; the closer the measuring probe 401 is to the conductive substrate, the greater the eddy current and the greater the reflection impedance. This feedback action quantity characterizes the size of the distance between the measuring probe 401 and the conductive substrate, that is, the size of the thickness of the non-conductive coating on the conductive substrate. The resolution of the eddy current coating thickness gauge reaches 0.1 micron, the allowable error reaches 1%, and the measuring range reaches 10 mm. The eddy current coating thickness gauge is suitable for measuring the film thickness on non-ferromagnetic metal substrates. The eddy current coating thickness gauge can be used to measure the non-conductive coatings on all conductors, such as the paint, plastic coatings and anodic oxidation films on the surface of aerospace aircraft, 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.

[0118] According to some embodiments of the present application, the thickness H of the insulating layer 24 on the housing 22 is 80 micrometers to 200 micrometers.

[0119] The insulating property of the insulating layer 24 refers to the dielectric strength and the withstand voltage breakdown property of the insulating layer 24.

[0120] The dielectric strength is a measure of the electrical strength of a material as an insulator. The dielectric strength is defined as the maximum voltage per unit thickness that an insulator can withstand before breakdown, expressed in volts per unit thickness; the greater the dielectric strength of an insulating material, the better the quality as an insulator. The dielectric strength of the insulating layer 24 is related to the insulating material used for the insulating layer 24. When the same insulating material is used, the dielectric strength of the insulating layer 24 is the same.

[0121] The breakdown of the insulating layer 24 is that under the action of a strong electric field, the insulating layer 24 loses its electrical insulation ability and suddenly changes from an insulating state to a good conductive state. The lowest critical voltage that causes the 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. When the dielectric strength of the insulating layer 24 is the same, the thicker the insulating layer 24, the higher the breakdown voltage of the insulating layer 24, and the better the withstand voltage breakdown property of the insulating layer 24.

[0122] It can be seen that the thickness of the insulating layer 24 affects the insulating property of the insulating layer 24, and thus affects the safety performance and yield of the battery cell 20; in addition, the thickness of the insulating layer 24 also affects the appearance and volume size of the battery cell 20, and thus affects the subsequent assembly and material cost of the battery cell 20. And because electrostatic spraying is used, an insulating layer 24 with higher uniformity can be obtained, which is beneficial to reducing the thickness of the insulating layer 24 while ensuring the insulating property of the insulating layer 24 and ensuring a high yield.

[0123] By setting the thickness H of the insulating layer 24 to be 80 micrometers to 200 micrometers, the housing 22 has good insulating properties, ensuring 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, facilitating the subsequent assembly of the battery cell 20, improving production efficiency, ensuring a high yield, and also being beneficial to saving materials and reducing production costs.

[0124] According to some embodiments of the present application, the thickness H of the insulating layer 24 is 110 micrometers to 120 micrometers.

[0125] Further setting the thickness H of the insulating layer 24 to be 110 micrometers to 120 micrometers is beneficial to better balance the insulating property of the housing 22, the appearance volume of the battery cell 20, and the yield, and to reduce production costs, being suitable for large-scale mass production.

[0126] Taking the insulating material of the insulating layer 24 as a photo-curable insulating resin material as an example, the insulation performance and yield of the battery cell 20 with insulating layers 24 of different thicknesses are tested. The test results are shown in Table 1 below.

[0127] Table 1 - Test Results of Insulation Performance and Yield of Battery Cell 20 with Insulating Layers 24 of Different Thicknesses

[0128]

[0129] In Table 1, the unit of the thickness H of the insulating layer 24 is micrometer (μm); the unit of the dielectric strength is kilovolt per millimeter (KV / mm); in the withstand voltage breakdown performance, under the strong electric field of a DC voltage of 2700 volts (DC2700V), a leakage current less than or equal to 0.1 milliampere (≤0.1mA) is qualified, and a leakage current greater than 0.1 milliampere (>0.1mA) is failed.

[0130] It can be seen that when the thickness H of the insulating layer 24 is in the range of 80 micrometers to 200 micrometers, the battery cell 20 has good insulation performance, and better controls the appearance and volume of the battery cell 20, and ensures a high yield; when the thickness H of the insulating layer 24 is in the range of 110 micrometers to 120 micrometers, the battery cell 20 can better balance the insulation performance, appearance, volume and yield, and is beneficial to reducing the production cost.

[0131] According to some embodiments of the present application, with reference to Figure 2 , the present application provides a battery 100. The battery 100 includes a box body 10 and the battery cell 20 provided by the above embodiments, and the battery cell 20 is accommodated in the box body 10.

[0132] Since the battery 100 has the same technical effects as the above-mentioned battery cell 20, it will not be elaborated here.

[0133] According to some embodiments of the present application, the present application further provides an electrical device. The electrical device includes the battery 100 or the battery cell 20 provided by the above embodiments, and the battery 100 and the battery cell 20 are used to provide electrical energy for the electrical device.

[0134] The electrical device can be any of the aforementioned devices or systems using the battery 100. Since the electrical device has the same technical effects as the above-mentioned battery 100 and battery cell 20, it will not be elaborated here either.

[0135] 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 foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present application, and they should all be covered within the scope of the claims and the specification of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A method for preparing a battery cell, characterized in that, the method for preparing the battery cell includes: determining that the battery cell is in an uncharged state; spraying an insulating material onto at least a part of the outer surface of the housing of the battery cell by means of electrostatic spraying; performing a curing treatment on the area of the housing sprayed with the insulating material to obtain a battery cell including an insulating layer; injecting an electrolyte into the battery cell including the insulating layer.

2. The method for preparing a battery cell according to claim 1, characterized in that, the insulating material is a photo-curable insulating resin material; the performing a curing treatment on the area of the housing sprayed with the insulating material includes: irradiating the area of the housing sprayed with the insulating material with ultraviolet light to cure the insulating material.

3. The method for preparing a battery cell according to claim 1, characterized in that, the insulating material is an aqueous coating or a solvent-based coating; the performing a curing treatment on the area of the housing sprayed with the insulating material includes: performing a baking treatment on the battery cell to cure the insulating material; wherein, the baking temperature is greater than 60°C and less than 200°C.

4. The method for preparing a battery cell according to any one of claims 1 to 3, characterized in that, after obtaining the battery cell including the insulating layer and before injecting the electrolyte into the battery cell including the insulating layer, it further includes: performing an insulation detection on the housing.

5. The method for preparing a battery cell according to any one of claims 1 to 3, characterized in that, before spraying the insulating material onto at least a part of the outer surface of the housing of the battery cell by means of electrostatic spraying, it further includes: performing a cleaning treatment on the outer surface of the housing.

6. A battery cell, characterized in that, the battery cell is prepared according to the method for preparing a battery cell according to any one of claims 1 to 5; the battery cell includes: a housing, and an insulating layer is provided on at least a part of the outer surface of the housing; a core component, and the core component is accommodated in the housing; and an end cap, and the end cap covers the opening of the housing.

7. The battery cell according to claim 6, characterized in that, the thickness of the insulating layer on the housing is 80 microns to 200 microns.

8. The battery cell according to claim 7, characterized in that, the thickness of the insulating layer is 110 microns to 120 microns.

9. A battery, characterized in that, the battery includes the battery cell according to any one of claims 6 to 8.

10. An electrical device, characterized in that, the electrical device includes the battery according to claim 9 or the battery cell according to any one of claims 6 to 8, and the battery and the battery cell are used to provide electrical energy.

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