Preparation process for battery cell, and battery cell, battery and electric device

Abstract

A preparation process for a battery cell. The preparation process comprises the following steps: baking an electrode assembly; mixing the baked electrode assembly with an electrolytic solution containing a monomer and a free radical initiator, and performing activation treatment, so as to obtain a semi-finished product containing a gel-state electrolyte; and coating the outside of the semi-finished product with an insulating film. The insulating film plays an insulating isolation role between the semi-finished product and the inner wall of a casing, and the semi-finished product in a gel state can reduce the degree of freedom of the electrolytic solution on the basis of ensuring that the electrolytic solution fully infiltrates the electrode assembly, such that the electrolytic solution is more stably wrapped in the insulating film, thereby reducing the probability of the electrolytic solution moving to between the electrode assembly and the inner wall of the casing, and improving the voltage breakdown resistance of a battery cell.

Description

A preparation process of a battery cell, a battery cell, a battery and an electrical device

[0001] Related applications

[0002] This application claims priority to Chinese patent application No. 2023114259294, filed on October 31, 2023, entitled “A process for preparing a battery cell, a battery cell, a battery and an electrical device,” the entire text of which is hereby incorporated by reference. Technical Field

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

[0004] In actual use, battery cell insulation failure often occurs. When a battery cell insulation failure occurs, it is easy for the electrode assembly inside the battery cell to conduct electricity with the casing, resulting in a decrease in the battery cell's voltage breakdown resistance and an increased risk of battery cell failure.

[0005] Summary of the Invention

[0006] Based on this, it is necessary to provide a battery cell preparation process, a battery cell, a battery and an electrical device to address the problem that current battery cells are prone to insulation failure, which leads to a reduction in the voltage breakdown resistance of the battery cells.

[0007] In a first aspect, the present application provides a process for preparing a battery cell, comprising the following steps:

[0008] baking the electrode assembly;

[0009] The baked electrode assembly is mixed with an electrolyte solution containing a monomer and a free radical initiator, and activated to obtain a semi-finished product containing a gel electrolyte;

[0010] An insulating film is coated on the semi-finished product.

[0011] Through the above steps, first, monomers and free radical initiators are added to the electrode assembly mixed with the electrolyte, and then a semi-finished product containing a gel electrolyte is obtained after activation treatment, and an insulating film is coated on the outside of the semi-finished product. When the semi-finished product coated with the insulating film is placed in a shell, the insulating film acts as an insulating isolation between the semi-finished product and the inner wall of the shell, and the electrolyte is in a gel state, so that the electrolyte is more stably coated in the insulating film, reducing the probability of the electrolyte moving between the electrode assembly and the inner wall of the shell to conduct the circuit between the electrode assembly and the shell, thereby improving the voltage breakdown resistance of the battery cell.

[0012] In some embodiments, the monomer includes one or more of vinyl vinyl sulfite, methyl methacrylate, and pentaerythritol tetraacrylate.

[0013] In some embodiments, the free radical initiator includes one or more of azobisisobutyronitrile, dimethyl azobisisobutyrate, and azobisisoheptanenitrile.

[0014] In some embodiments, the mass ratio of free radical initiator to monomer is in the range of 1:1 to 1:10.

[0015] In some embodiments, the step of mixing the baked electrode assembly with an electrolyte solution containing a monomer and a free radical initiator and subjecting the mixture to an activation treatment to obtain a semi-finished product containing a gel electrolyte specifically includes:

[0016] The activation treatment adopts high temperature treatment and / or ultraviolet activation treatment.

[0017] In some embodiments, the temperature range of the high temperature treatment is 50 degrees Celsius (° C.) to 100 degrees Celsius (° C.).

[0018] In some embodiments, the high temperature treatment time ranges from 0.5 hours (h) to 12 hours (h).

[0019] In some embodiments, the UV activation treatment time ranges from 5 seconds (s) to 300 seconds (s).

[0020] In some embodiments, the air permeability of the insulating film is not greater than 10 L / (m 2 ·24h).

[0021] In some embodiments, after the step of coating the semi-finished product with an insulating film, the method further comprises the following steps:

[0022] The semi-finished product coated with the insulating film is placed in a shell, and is welded and sealed to obtain a battery cell.

[0023] In some embodiments, before the step of baking the electrode assembly, the method further includes the following steps:

[0024] The positive electrode sheet, separator, and negative electrode sheet are stacked and wound in sequence to obtain an electrode assembly.

[0025] In a second aspect, the present application further provides a battery cell, comprising:

[0026] electrode assembly;

[0027] gel electrolyte; and

[0028] The insulating film is coated on the electrode assembly and the gel electrolyte.

[0029] In some embodiments, the air permeability of the insulating film is not greater than 10 L / (m 2 ·24h).

[0030] In some embodiments, the battery cell further includes a housing, and the electrode assembly coated with an insulating film and the gel electrolyte are accommodated in the housing.

[0031] In some embodiments, the battery cell further includes an end cover, the end cover being sealed to the opening of the housing;

[0032] The end cover is formed with an electrode terminal and an explosion-proof valve, and other areas of the end cover except the electrode terminal and the explosion-proof valve are constructed as a continuously arranged closed plane.

[0033] In a third aspect, the present application also provides a battery comprising the battery cell described above.

[0034] In a fourth aspect, the present application also provides an electrical device comprising the battery as described above.

[0035] The preparation process of the above-mentioned battery cell, battery cell, battery and electrical device, add a monomer and a free radical initiator to an electrode assembly mixed with an electrolyte, and then obtain a semi-finished product containing a gel electrolyte after activation treatment, and coat the semi-finished product with an insulating film. When the semi-finished product coated with the insulating film is placed in a shell, the insulating film acts as an insulating isolation between the semi-finished product and the inner wall of the shell, and the electrolyte is in a gel state, so that the electrolyte is more stably coated in the insulating film, reducing the probability of the electrolyte moving between the electrode assembly and the inner wall of the shell to conduct the circuit between the electrode assembly and the shell, thereby improving the voltage breakdown resistance of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to 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 ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0037] FIG1 is a schematic structural diagram of a vehicle according to one or more embodiments.

[0038] FIG2 is a schematic diagram of an exploded structure of a battery according to one or more embodiments.

[0039] FIG3 is a schematic diagram of an exploded structure of a battery cell according to one or more embodiments.

[0040] FIG. 4 is a flow chart of a process for preparing a battery cell according to one or more embodiments.

[0041] Explanation of the reference numerals: 1000, vehicle; 100, battery; 200, controller; 300, motor; 10, housing; 20, battery cell; 11, first part; 12, second part; 21, end cover; 22, housing; 23, electrode assembly; 21a, electrode terminal. DETAILED DESCRIPTION

[0042] 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.

[0043] In the description of this application, it should be understood that if 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. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing this application and simplifying the description, and does 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 this application.

[0044] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this application, if the term "plurality" appears, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0045] In this application, unless otherwise specified or limited, the terms "mounted," "connected," "connected," "fixed," etc., should be interpreted broadly. For example, these terms may refer to fixed connections, removable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediary; and internal communication between two components or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0046] In this application, unless otherwise expressly specified or limited, if a first feature is described as being "above" or "below" a second feature, or similar descriptions, this may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is described as being "above," "above," or "above" a second feature, it may 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 described as being "below," "below," or "below" a second feature, it may 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.

[0047] It should be noted that if 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. If 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. If any, 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 embodiment.

[0048] 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 such as electric bicycles, electric motorcycles, and electric vehicles, as well as in other fields. As the application of power batteries continues to expand, market demand is also growing.

[0049] The battery is composed of one or more battery cells. The structure of each battery cell includes end caps, shells, electrode assemblies and other functional components. Among them, the electrode assembly is the component in the battery cell where the electrochemical reaction occurs, and one or more electrode assemblies can be placed in the shell. The electrode assembly is mainly formed by winding or stacking the 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 materials constitute the main body of the electrode assembly, and the parts of the positive and negative electrode sheets without active materials each constitute the tabs. The positive and negative tabs can 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 material and the negative active material react with the electrolyte, and the tabs connect the electrode terminals to form a current loop.

[0050] During the assembly of a battery cell, the positive electrode sheet, separator, and negative electrode sheet are first stacked in sequence and wound to form an electrode assembly. An insulating film is then applied to the outside of the electrode assembly. The electrode assembly is then placed in a housing, with end caps sealed against the housing openings. The housing is then filled with electrolyte through the inlet on the end caps, ensuring that the electrolyte fully soaks into the electrode assembly.

[0051] In this way, in the assembled battery cell, some free electrolyte will be located between the insulating film outside the electrode assembly and the inner wall of the shell.

[0052] Furthermore, during the assembly or use of a battery cell, the insulating film may rupture due to burrs or other structures on the electrode assembly or casing, or during placement into the casing. Once the insulating film ruptures, the free electrolyte between the insulating film and the inner wall of the casing can conduct a circuit between the electrode assembly and the casing, causing insulation failure in the battery cell and reducing the cell's voltage breakdown resistance, posing a risk of cell failure.

[0053] In order to solve the problem that current battery monomers are prone to insulation failure, thereby reducing the voltage breakdown resistance of the battery monomers, a battery monomer preparation process is proposed in one or more embodiments of the present application. First, monomers and free radical initiators are added to an electrode assembly mixed with an electrolyte. Then, after activation treatment, a semi-finished product containing a gel electrolyte is obtained, and an insulating film is coated on the outside of the semi-finished product. When the semi-finished product coated with the insulating film is placed in a shell, the insulating film plays an insulating isolation role between the semi-finished product and the inner wall of the shell, and the electrolyte is in a gel state, so that the electrolyte is more stably coated in the insulating film, reducing the probability of the electrolyte moving between the electrode assembly and the inner wall of the shell, thereby conducting a circuit between the electrode assembly and the shell, and improving the voltage breakdown resistance of the battery monomer.

[0054] The battery cells disclosed in the embodiments of the present application can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft. The embodiments of the present application provide an electrical device that uses a battery as a power source. The electrical device can 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, and the like. Electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, among others.

[0055] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device according to an embodiment of the present application.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] Each battery cell 20 may be a secondary battery or a primary battery, and may also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be cylindrical, flat, rectangular, or in other shapes.

[0061] 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, an electrode assembly 23, and other functional components.

[0062] 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 fit the housing 22. Optionally, 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, thereby providing the battery cell 20 with 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 electrode assembly 23 for inputting or outputting electrical energy from 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 particular 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.

[0063] 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 electrode 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. Specifically, 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, or a hexagonal prism. Specifically, the shape of the housing 22 can be determined based on the specific shape and size of the electrode 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 particular limitations on this.

[0064] The electrode assembly 23 is a component in the battery cell 20 where electrochemical reactions occur. One or more electrode assemblies 23 may be contained in the housing 22. The electrode 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 materials constitute the main body of the electrode assembly, and the parts of the positive and negative electrode sheets without active materials each constitute a tab. 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 electrode active material and the negative electrode active material react with the electrolyte, and the tabs connect the electrode terminals to form a current loop.

[0065] 4 , an embodiment of the present application provides a process for preparing a battery cell, including the following steps:

[0066] S10: Bake the electrode assembly.

[0067] Specifically, the electrode assembly is placed in an environment of 70°C-120°C and baked for a period of time, which can remove moisture inside the positive and negative electrodes in the electrode assembly and reduce the impact of moisture or other impurities in the positive and negative electrodes.

[0068] During the baking process of the electrode assembly, the moisture content in the electrode assembly may be continuously detected until the moisture content in the electrode assembly drops to a target range.

[0069] S20: mixing the baked electrode assembly with an electrolyte containing a monomer and a free radical initiator, and performing an activation treatment to obtain a semi-finished product containing a gel electrolyte.

[0070] Specifically, the baked electrode assembly is mixed with the electrolyte in a certain proportion so that the electrolyte can be adsorbed in the pores of the positive electrode sheet and the negative electrode sheet and on the surface of the diaphragm, so that the electrolyte fully infiltrates the electrode assembly.

[0071] Alternatively, the electrode assembly can be first filled with electrolyte to allow the electrolyte to be fully absorbed into the pores of the positive and negative electrode sheets and on the surface of the separator. The electrolyte-soaked electrode assembly is then filled with monomer and free radical initiator to ensure that the mixture of monomer and free radical initiator is fully filled. An activation treatment is then performed to solidify the electrolyte in the electrode assembly, thereby obtaining a semi-finished product containing a gel electrolyte.

[0072] In this way, after the electrode assembly is assembled to form a battery cell, during the charge and discharge process of the battery cell, the positive electrode active material on the positive electrode sheet and the negative electrode active material on the negative electrode sheet can react smoothly with the electrolyte, so that a current circuit is smoothly formed between the electrode tab and the electrode terminal on the end cover.

[0073] Furthermore, during the mixing process of the electrode assembly and the electrolyte, the degree of electrolyte infiltration can be monitored by detection or observation until the electrolyte is fully infiltrated.

[0074] Furthermore, it should be noted that the gel state refers to an elastic semi-solid state with a certain fixed structure and a certain degree of elasticity and deformability. Compared to the liquid state, the gel state has a lower degree of freedom, which can reduce the probability of movement between the electrode assembly and the inner wall of the housing.

[0075] S30: Wrapping the semi-finished product with an insulating film.

[0076] The insulating film can play a role of insulating isolation between the semi-finished product and the shell, further reducing the probability of the electrolyte moving between the insulating film and the inner wall of the shell.

[0077] Alternatively, the insulating film can be wrapped around the semi-finished product using a plastic seal, or the insulating film can be prefabricated to form a five-sided sealed container with one open side, and the semi-finished product placed in the container. The tabs in the semi-finished product can extend through one side of the container opening and connect to the electrode terminals on the end cap.

[0078] Through the above steps, first, monomers and free radical initiators are added to the electrode assembly mixed with the electrolyte, and then a semi-finished product containing a gel electrolyte is obtained after activation treatment, and an insulating film is coated on the outside of the semi-finished product. When the semi-finished product coated with the insulating film is placed in a shell, the insulating film acts as an insulating isolation between the semi-finished product and the inner wall of the shell, and the electrolyte is in a gel state, so that the electrolyte can be more stably coated in the insulating film, reducing the probability of the electrolyte moving between the electrode assembly and the inner wall of the shell to conduct the circuit between the electrode assembly and the shell, thereby improving the voltage breakdown resistance of the battery cell.

[0079] In some embodiments, the monomer includes one or more of vinyl vinyl sulfite, methyl methacrylate, and pentaerythritol tetraacrylate.

[0080] Furthermore, the free radical initiator includes one or more of azobisisobutyronitrile, dimethyl azobisisobutyrate and azobisisoheptonitrile.

[0081] The monomer and the free radical initiator can act together on the electrode assembly mixed with the electrolyte and undergo a cross-linking reaction to obtain a semi-finished product containing a gel electrolyte. On the one hand, this allows for stable contact between the electrolyte and the electrode assembly; on the other hand, it reduces the probability of the electrolyte moving between the insulating film and the inner wall of the shell, thereby causing insulation failure of the battery cell.

[0082] In some embodiments, the mass ratio of free radical initiator to monomer is in the range of 1:1 to 1:10.

[0083] As an example, the mass ratio of free radical initiator to monomer can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10.

[0084] Thus, the free radical initiator and the monomer can act together on the electrode assembly mixed with the electrolyte to smoothly form a semi-finished product containing the gel electrolyte.

[0085] In some embodiments, the step S20 of mixing the baked electrode assembly with an electrolyte solution containing a monomer and a free radical initiator and subjecting the mixture to an activation treatment to obtain a semi-finished product containing a gel electrolyte specifically includes:

[0086] The activation treatment adopts high temperature treatment and / or ultraviolet activation treatment.

[0087] Specifically, after adding a free radical initiator and a monomer to an electrode assembly mixed with an electrolyte, a high temperature treatment or an ultraviolet activation treatment is performed to allow the free radical initiator and the monomer to react smoothly with the electrolyte, thereby successfully obtaining a gel electrolyte.

[0088] In some embodiments, the temperature range of the high temperature treatment is 50° C.-100° C. Further, the time range of the high temperature treatment is 0.5 h-12 h.

[0089] Specifically, during the high-temperature treatment of the electrode assembly, monomer, and free radical initiator mixed with the electrolyte, they are placed in an environment with a temperature of 50° C.-100° C. for 0.5 h-12 h to smoothly form a semi-finished product containing a gel electrolyte.

[0090] As an example, the temperature of the high temperature treatment may be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, or 100°C.

[0091] As an example, the time of high temperature treatment can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h, 10.5h, 11h, 11.5h or 12h.

[0092] In some embodiments, the UV activation treatment time ranges from 5 seconds to 300 seconds.

[0093] As an example, the time of the UV activation treatment can be 5 s, 35 s, 65 s, 95 s, 125 s, 155 s, 185 s, 215 s, 245 s, 275 s or 300 s.

[0094] In some embodiments, the air permeability of the insulating film is not greater than 10 L / (m 2 ·24h).

[0095] It should be noted that the traditional insulating film has many pores, or through holes need to be opened on the insulating film. After the insulating film is wrapped around the outside of the electrode assembly and placed in the shell, the electrolyte is filled into the shell. At this time, the electrolyte needs to flow between the positive and negative electrode sheets with the help of the through holes on the insulating film so that the electrolyte can be fully infiltrated.

[0096] However, during the injection process, the electrolyte can flow through the pores in the insulating film from one side of the electrode assembly through the insulating film to between the insulating film and the inner wall of the housing. As a result, some electrolyte becomes free between the insulating film and the inner wall of the housing. When the battery cell insulation fails, the free electrolyte creates a conductive circuit between the electrode assembly and the housing, reducing the battery cell's withstand voltage breakdown capability and increasing the risk of failure.

[0097] Therefore, in this application, the air permeability of the insulating film is controlled at 10L / (m 2·24h) and below 10L / (m2·24h), which can further reduce the probability of the electrolyte passing through the insulating film and moving between the insulating film and the inner wall of the shell, thereby further improving the voltage breakdown resistance of the battery cell and reducing the failure risk of the battery cell.

[0098] Specifically, the air permeability of the insulating film can be tested using methods known in the art. For example, the insulating film is punched into small discs with a diameter of 50 mm, and the small discs are tested for air permeability using a Wang Yan-type air permeability meter (Asahi Seiko model EG01-55-1MR). The time taken for 100 mL of gas (such as air) to pass through can be used to obtain the air permeability of the insulating film.

[0099] Furthermore, in order to test the actual voltage breakdown resistance of the battery cells prepared using the preparation process of the present application, the following tests were conducted:

[0100] It should be noted that the above-mentioned insulating film A refers to the current conventional porous insulating film, and the insulating film B is the insulating film provided by this application, that is, under the condition of 0.1 MPa, the air permeability of the insulating film B is not greater than 10L / (m2·24h).

[0101] A voltage of 200 V was applied between the negative electrode column and the shell of the battery cells in Comparative Example 1, Example 1, and Example 2, and the test results were observed.

[0102] Among them, in Comparative Example 1, a traditional liquid electrolyte and a traditional porous insulating film were used, and the impedance between the pole and the shell was about 50Ω. After a voltage of 200V was applied between the negative pole and the shell of the battery cell, the battery cell caught fire in 1s.

[0103] In Example 1, a gel electrolyte and a conventional perforated insulating film were used. The impedance between the electrode and the housing was approximately 200Ω-1000Ω. After applying a voltage of 200V between the negative electrode and the housing, the battery cell caught fire within 7 seconds. The test results show that Example 1, compared to Comparative Example 1, can delay the onset of battery fire, thereby improving the battery cell's voltage breakdown resistance to a certain extent.

[0104] In Example 2, a gel electrolyte and the insulating film provided by the present application were used, and the impedance between the pole and the shell was greater than 10 kΩ. After a voltage of 200 V was applied between the negative pole and the shell of the battery cell, the battery cell did not catch fire within 2 hours.

[0105] It can be seen that the use of the insulating film provided in this application can further improve the voltage breakdown resistance of the battery cell. And the battery cell produced using the preparation process provided in this application can effectively improve the voltage breakdown resistance of the battery cell and reduce the failure risk of the battery cell.

[0106] In addition, the insulating film can be made of, but is not limited to, electrolyte-resistant polymer materials such as PE, PP, PET, PA, PI, and PTFE. This can reduce the corrosion effect of the electrolyte on the insulating film, allowing the insulating film to more stably play an insulating and isolating role between the electrode assembly and the shell.

[0107] In some embodiments, after step S30 of coating the semi-finished product with an insulating film, the method further includes the following steps:

[0108] S40: placing the semi-finished product coated with the insulating film into a shell, and performing welding and sealing to obtain a battery cell.

[0109] After the semi-finished product is placed in the housing, an insulating film is sandwiched between the semi-finished product and the housing. This film insulates and isolates the semi-finished product from the housing. It also protects and covers the semi-finished product, reducing the likelihood of scratches and damage to the semi-finished product during placement.

[0110] It should be noted that in the current battery cell assembly process, the electrode assembly needs to be placed in the shell first, the end cover seals the shell, and then liquid is injected into the shell through the liquid injection port on the end cover.

[0111] However, this method not only causes some electrolyte to be injected between the insulating film and the inner wall of the housing, thereby increasing the risk of battery failure, but also causes electrolyte residue to remain around the injection port during the injection process, causing electrolyte corrosion to the end cap and housing.

[0112] Compared to the current battery cell assembly process, this application completes the mixing and infiltration of the electrolyte and electrode assembly before the semi-finished product is placed in the shell, effectively reducing the probability of electrolyte corrosion of the end caps and shell. Furthermore, the insulating film covering the exterior of the semi-finished product also reduces the probability of electrolyte migration between the insulating film and the inner wall of the shell, improving the battery cell's voltage breakdown resistance and reducing the risk of battery cell failure.

[0113] In some embodiments, before the step S10 of baking the electrode assembly, the following steps are further included:

[0114] S01: stacking the positive electrode sheet, separator, and negative electrode sheet in sequence and winding them to obtain an electrode assembly.

[0115] Specifically, the positive electrode sheet, the separator, and the negative electrode sheet are first stacked in sequence and then wound to obtain an electrode assembly.

[0116] Based on the same concept as the above-mentioned preparation process, the present application also provides a battery cell, including an electrode assembly, a gel electrolyte and an insulating film, wherein the insulating film is coated on the outside of the electrode assembly and the gel electrolyte.

[0117] It should be noted that the battery cells can be manufactured using the above-described manufacturing process, namely, first preparing an electrode assembly and an electrolyte containing the cells and a free radical initiator, baking the electrode assembly, then mixing the baked electrode assembly with the electrolyte, and performing an activation treatment to obtain a semi-finished product containing a gel electrolyte. Furthermore, an insulating film is coated on the semi-finished product.

[0118] Therefore, in the battery cell provided by this application, the electrolyte is in a gel state, allowing it to be more stably encapsulated in the insulating film. Thus, when the semi-finished product coated with the insulating film is placed in a housing, the insulating film acts as an insulator between the semi-finished product and the inner wall of the housing. The gel electrolyte is more stably encapsulated in the insulating film, reducing the probability of the electrolyte migrating between the electrode assembly and the inner wall of the housing, thereby establishing a circuit between the electrode assembly and the housing, and improving the battery cell's voltage breakdown resistance.

[0119] In some embodiments, the air permeability of the insulating film is not greater than 10 L / (m 2 ·24h).

[0120] Compared with the traditional insulating film, the insulating film provided by the present application has an air permeability of 10L / (m 2 24h) and 10L / (m 2 · 24h) or less. In this way, the probability of the electrolyte passing through the insulating film and moving between the insulating film and the inner wall of the shell can be further reduced, thereby further improving the voltage breakdown resistance of the battery cell and reducing the failure risk of the battery cell.

[0121] In some embodiments, the battery cell further includes a housing, and the electrode assembly coated with an insulating film and the gel electrolyte are accommodated in the housing.

[0122] After the semi-finished product is placed in the housing, an insulating film is sandwiched between the semi-finished product and the housing. This film insulates and isolates the semi-finished product from the housing. It also protects and covers the semi-finished product, reducing the likelihood of scratches and damage to the semi-finished product during placement.

[0123] In some embodiments, the battery cell further includes an end cap that is sealed to the opening of the housing, wherein the end cap is formed with electrode terminals and an explosion-proof valve, and the area of ​​the end cap other than the electrode terminals and the explosion-proof valve is configured as a continuous closed plane.

[0124] Specifically, other areas on the end cover except the electrode terminals and the explosion-proof valve are constructed as continuously arranged closed planes, which means that other areas on the end cover except the electrode terminals and the explosion-proof valve do not need to have holes opened.

[0125] It's important to note that the traditional manufacturing process involves placing the electrode assembly into the housing first, followed by electrolyte filling. This method requires opening an injection hole in the end cap of the battery cell, through which the electrolyte is poured into the housing. After filling, the injection hole is sealed with a sealing pin.

[0126] In the battery cells produced using the manufacturing process of this application, the electrolyte and electrode assembly are mixed before being placed in the housing, and the electrolyte is activated to form a gel electrolyte. Therefore, after placing the semi-finished product containing the gel electrolyte in the housing, the housing is sealed with the end caps to complete the assembly of the battery cells. There is no need to inject liquid into the housing, and therefore, there is no need to provide an injection hole in the end caps.

[0127] With the above structure, since there is no need to provide a liquid injection hole on the end cover, the overall sealing performance of the battery cell can be improved, making the overall structure of the battery cell more stable.

[0128] Based on the same concept as the above-mentioned battery cell, the present application also provides a battery, including the above-mentioned battery cell.

[0129] Based on the same concept as the above-mentioned battery, the present application also provides an electrical device, including the above-mentioned battery.

[0130] According to one or more embodiments, a positive electrode sheet, a separator, and a negative electrode sheet are stacked in sequence and wound to form an electrode assembly. The wound electrode assembly is then baked at 70°C to 120°C for a period of time to remove moisture from the positive and negative electrode sheets.

[0131] Then, the baked electrode assembly is mixed with the electrolyte in a certain proportion so that the electrolyte can be adsorbed in the pores of the positive and negative electrode sheets and the surface of the diaphragm, allowing the electrolyte to fully infiltrate the electrode assembly.

[0132] A monomer and a free radical initiator are added to the electrode assembly mixed with the electrolyte, and then subjected to high-temperature treatment or UV activation to obtain a semi-finished product containing a gel electrolyte. An insulating film is then wrapped around the periphery of the semi-finished product. The semi-finished product and the insulating film are then placed into a housing. The end caps are sealed to the openings of the housing using laser welding, thus completing the battery cell.

[0133] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0134] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A process for preparing a battery cell, comprising the following steps: baking the electrode assembly; The baked electrode assembly is mixed with an electrolyte solution containing a monomer and a free radical initiator, and subjected to activation treatment to obtain a semi-finished product containing a gel electrolyte; An insulating film is coated on the semi-finished product.

2. The process for preparing a battery cell according to claim 1, wherein: The monomers include one or more of vinyl sulfite, methyl methacrylate and pentaerythritol tetraacrylate.

3. The process for preparing a battery monomer according to claim 1 or 2, wherein: The free radical initiator includes one or more of azobisisobutyronitrile, dimethyl azobisisobutyrate and azobisisoheptanenitrile.

4. The process for preparing a battery monomer according to any one of claims 1 to 3, wherein: The mass ratio of the free radical initiator to the monomer is in the range of 1:1-1:

10.

5. The process for preparing a battery monomer according to any one of claims 1 to 4, wherein: The step of mixing the baked electrode assembly with an electrolyte solution containing a monomer and a free radical initiator and subjecting the mixture to an activation treatment to obtain a semi-finished product containing a gel electrolyte specifically includes: The activation treatment adopts high temperature treatment and / or ultraviolet activation treatment.

6. The process for preparing a battery monomer according to claim 5, wherein: The temperature range of the high temperature treatment is 50°C-100°C.

7. The process for preparing a battery monomer according to claim 5 or 6, wherein: The time range of the high temperature treatment is 0.5h-12h.

8. The process for preparing a battery monomer according to any one of claims 5 to 7, wherein: The time range of the ultraviolet activation treatment is 5s-300s.

9. The process for preparing a battery monomer according to any one of claims 1 to 8, wherein: Under the condition of 0.1MPa, the air permeability of the insulating film is not greater than 10L / (m 2 ·24h).

10. The process for preparing a battery monomer according to any one of claims 1 to 9, wherein: After the step of coating the semi-finished product with an insulating film, the step further includes: The semi-finished product coated with the insulating film is placed in a shell, and is welded and sealed to obtain a battery cell.

11. The process for preparing a battery monomer according to any one of claims 1 to 10, wherein: Before the step of baking the electrode assembly, the method further includes the following steps: The positive electrode sheet, separator, and negative electrode sheet are stacked and wound in sequence to obtain an electrode assembly.

12. A battery cell, comprising: Electrode assembly; Gel electrolyte; and The insulating film is coated on the electrode assembly and the gel electrolyte.

13. The battery cell according to claim 12, wherein: Under the condition of 0.1MPa, the air permeability of the insulating film is not greater than 10L / (m 2 ·24h).

14. The battery cell according to claim 12 or 13, wherein: The battery cell further includes a housing, in which the electrode assembly coated with the insulating film and the gel electrolyte are accommodated.

15. The battery cell according to claim 14, wherein: The battery cell further includes an end cover, which is sealed at the opening of the shell; The end cover is formed with an electrode terminal and an explosion-proof valve, and other regions of the end cover except the electrode terminal and the explosion-proof valve are constructed as a continuously arranged closed plane.

16. A battery comprising the battery cell according to any one of claims 12 to 15.

17. An electrical device comprising the battery as claimed in claim 16.

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