Battery cell and preparation method, battery, and electrical device

Abstract

The present application relates to a battery cell and a preparation method, a battery, and an electrical device. An electrode assembly comprises an electrode sheet and a plurality of bosses; the electrode sheet is of a wound structure; and the plurality of bosses are at least partially arranged on the electrode sheet in the winding direction of the electrode sheet. The bosses in the present application are arranged to achieve a supporting effect between two adjacent layers of the wound structure, and facilitate an increase in a distance between two adjacent layers of the wound structure, thereby enabling two adjacent layers of the wound structure to be looser, and facilitating reduction of the occurrence of breakage of the electrode sheet.

Description

Battery cell and preparation method, battery and power-using device

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on March 6, 2024, with application number 202410254159.X and invention name “Battery Cell and Preparation Method, Battery and Electrical Equipment”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the field of new energy technology, and in particular relates to a battery and an electrical device. Background Art

[0003] A battery cell is an electrical energy input and output unit in a battery, and a battery cell generally includes an electrode sheet.

[0004] In related technologies, the electrode sheets need to be configured in a wound state. However, after the electrode sheets are wound, the inner ring of the electrode sheets is prone to collapse, and the outer ring of the electrode sheets is prone to breakage. In view of this, how to improve the structural stability of the electrode sheets in battery cells is a technical problem that needs to be solved urgently.

[0005] Summary of the Invention

[0006] The purpose of the embodiments of the present application is to provide a battery cell and a preparation method, a battery and an electrical device, aiming to solve the technical problem of poor structural stability of electrode sheets. Technical Solutions

[0007] The technical solution adopted in the embodiment of this application is:

[0008] In a first aspect, an embodiment of the present application provides a battery cell, wherein the battery cell includes an electrode assembly, and the electrode assembly includes:

[0009] Electrode sheet, the electrode sheet is a retractable structure;

[0010] A plurality of bosses are at least partially arranged on the electrode sheet along the winding direction of the electrode sheet.

[0011] In the electrode sheet provided in the embodiment of the present application, by arranging multiple bosses on the electrode sheet, after the electrode sheet is rolled up, the bosses can play a supporting role between the two adjacent layers of the rolled-up structure, which is beneficial to increase the distance between the two adjacent layers of the rolled-up structure; that is, the multiple bosses can make the two adjacent layers of the rolled-up structure looser, which is beneficial to reduce the occurrence of breakage of the electrode sheet.

[0012] In some embodiments, the roll-up structure comprises an inner layer and an outer layer, with a plurality of bosses disposed on the inner layer. Thus, the bosses can provide support between the inner layer and adjacent layers, thereby ensuring a sufficient spacing between the inner layer and adjacent layers. In other words, this can facilitate a looser fit between the inner layer and adjacent layers of the roll-up structure, thereby reducing the risk of collapse of the inner layer of the electrode sheet.

[0013] In some embodiments, the boss is a deformable structure. Thus, during the formation of the rolled-up structure, the adjacent layers of the inner layer squeeze the boss on the inner layer. As the number of rolled-up layers increases, the squeezing force of the adjacent layers on the boss increases, and during this process, the boss gradually collapses and deforms, so that the inner layer and its adjacent layers change from being loose to being tight.

[0014] In some embodiments, the height of the multiple bosses decreases along the thickness of the electrode sheet as the electrode sheet is rolled up. This helps ensure that the height of the bosses on the inner layer and the bosses on the outer layer are consistent after deformation, thereby ensuring that the inner and outer layers are of the same tightness, or that the inner layer is looser than the outer layer, which helps reduce the risk of collapse of the inner layer of the electrode sheet.

[0015] In some embodiments, the plurality of bosses are spaced apart along the winding direction of the electrode sheet. In this way, the spacing of the plurality of bosses can make the adjacent layers of the winding structure looser, which is beneficial to reducing the possibility of breakage of the electrode sheet.

[0016] In some embodiments, each electrode sheet layer is provided with at least three bosses along the winding direction of the electrode sheet, and the distance between adjacent bosses gradually increases along the winding direction of the electrode sheet. This allows the inner layer of the winding structure to have denser bosses than the outer layer, which helps offset some of the squeezing force exerted by the outer layer on the inner layer, thereby improving the support stability of the inner layer.

[0017] In some embodiments, at least some of the plurality of bosses are connected to form convex strips, and the height of the convex strips decreases along the winding direction of the electrode sheet.

[0018] In some embodiments, a plurality of bosses are arranged along the winding direction to form a first boss column and a second boss column. The first boss column and the second boss column are arranged alternately along the width of the electrode sheet, and the bosses in the first boss column and the bosses in the second boss column are staggered in the width direction. This helps to improve the consistency of the spacing between adjacent layers of the winding structure along the width direction of the electrode sheet, thereby improving the structural stability of the electrode sheet after winding.

[0019] In some embodiments, the bosses in the first boss column and the bosses in the second boss column are arranged in a grid structure, and the smallest grid unit of the grid structure is an isosceles triangle. This helps further improve the support stability of the first boss column and the second boss column for other layer structures.

[0020] In some embodiments, the electrode sheet is configured so that the heights of the bosses in the same layer of the rolled-up structure are the same.

[0021] In some embodiments, the boss is provided on one side of the electrode sheet, and a groove is provided on the other side of the electrode sheet at a position corresponding to the boss. This facilitates forming the boss structure directly on the electrode sheet. For example, a pressing roller can be used to press the groove on one side of the electrode sheet while forming the boss on the other side.

[0022] In some embodiments, there are multiple grooves, and the grooves are arranged corresponding to the bosses.

[0023] In some embodiments, the boss has an abutment surface facing away from the electrode sheet, and at least a portion of the abutment surface is curved. Thus, the curved surface helps reduce the pressure exerted by the boss on another layer of the roll-up structure, thereby improving the structural strength of the roll-up structure.

[0024] In some embodiments, the curved surface is a cambered surface.

[0025] In some embodiments, the electrode sheet is provided with a predetermined area for arranging the bosses, and a spacing area is provided between the boundary of the predetermined area and the boundary of the electrode sheet. In this way, by reserving the spacing area for cutting, it is beneficial to avoid generating more metal burrs when cutting the electrode sheet.

[0026] In a second aspect, the present application further provides a method for preparing a battery cell, the method comprising:

[0027] providing an electrode sheet;

[0028] An embossing roller is used to roll on one side of the electrode sheet and press a plurality of grooves on the electrode sheet to form a boss on the other side of the electrode sheet away from the grooves; wherein the pressure of the embossing roller on the electrode sheet increases or decreases along the direction in which the embossing roller rolls on the electrode sheet.

[0029] In some embodiments, the step of providing a plurality of grooves on one side of the electrode sheet to form a boss on the other side of the electrode sheet away from the grooves includes:

[0030] An embossing roller is used to roll on one side of the electrode sheet and press a plurality of grooves on the electrode sheet; wherein the pressure of the embossing roller on the electrode sheet increases or decreases along the direction in which the embossing roller rolls on the electrode sheet.

[0031] In some embodiments, the electrode sheet is configured such that the heights of the plurality of projections decrease along the thickness direction of the electrode sheet from the inner layer to the outer layer of the rolled structure.

[0032] In a third aspect, the present application also provides a battery, which includes the above-mentioned battery cell.

[0033] In a fourth aspect, the present application also provides an electrical device, which includes the above-mentioned battery.

[0034] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0036] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0037] FIG2 is a schematic structural diagram of a battery provided in some embodiments of the present application;

[0038] FIG3 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0039] FIG4 is a schematic diagram of the structure of an electrode sheet provided in some embodiments of the present application;

[0040] FIG5 is a schematic structural diagram of electrode sheets provided in other embodiments of the present application;

[0041] FIG6 is an enlarged schematic diagram of a portion A of FIG5 provided in some embodiments of the present application;

[0042] FIG7 is a schematic structural diagram of a battery cell provided in some other embodiments of the present application;

[0043] FIG8 is a schematic structural diagram of an electrode sheet provided in some embodiments of the present application;

[0044] FIG9 is a diagram showing the steps of a method for preparing an electrode sheet according to some embodiments of the present application.

[0045] The accompanying drawings in the specific implementation manner are as follows:

[0046] 100-vehicle, 110-battery, 120-controller, 130-motor, 10-casing, 11-first part, 12-second part, 20-battery cell, 200-electrode assembly, 200a-positive electrode sheet, 200b-negative electrode sheet, 210-electrode sheet, 211-preset area, 212-spacer area, 213-inner layer, 214-outer layer, 220-boss, 230-groove, 240-first boss row, 250-second boss row, 300-diaphragm, a-winding direction, b-width direction, c-length direction. DETAILED DESCRIPTION

[0047] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0049] In the description of the embodiments of this application, the use of technical terms such as "first" and "second" is solely for the purpose of distinguishing different objects and should not be construed as indicating or implying relative importance or implicitly specifying the quantity, specific order, or primary and secondary relationship of the technical features indicated. In the description of the embodiments of this application, "plurality" means more than two, unless otherwise specifically defined.

[0050] Reference herein to an "embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0051] In the description of the embodiments of the present application, the term "plurality" refers to more than two (including two).

[0052] In the description of the embodiments of the present application, if technical terms such as "middle", "length" (width), "thickness", "up", "down", "inside", and "outside" appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings. It is only for the convenience of describing the embodiments of the present 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. Therefore, it cannot be understood as a limitation on the embodiments of the present application.

[0053] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, the technical terms "installed," "connected," "connected," "fixed," etc. should be understood in a broad sense. For example, it can mean a fixed connection, a detachable connection, or an integral connection; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal connection of two components or the interaction between two components. For those skilled in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0054] As the core unit of a battery, the structure and performance of a battery cell have a crucial impact on the performance and service life of the entire battery. Electrode sheets are a crucial component of the battery cell structure and are typically wound together to reduce volume and increase energy density. However, winding electrode sheets often encounters problems, such as inner layer collapse and outer layer fracture, which can affect the performance of the electrode sheet and the stability of the battery cell and battery.

[0055] During the production of battery cells, as the electrode sheet is wound, the different layers of the electrode sheet are subjected to compressive stress and slip, causing the inner layer of the electrode sheet to become tighter and tighter. In other words, in the wound electrode sheet, the distance between the inner layer and the adjacent layer of the electrode sheet is smaller than the distance between the outer layer and the adjacent layer. Therefore, after winding, the inner layer of the electrode sheet is more likely to collapse due to the compressive stress, which may lead to risks such as battery performance degradation and battery thermal runaway. In addition, after the electrode sheet is wound, the outer layer of the electrode sheet is subject to the expansion force of the inner layer and is prone to breakage.

[0056] In some cases, during actual testing or use of a battery cell, the electrode sheet may expand due to heat; thus, the collapse of the inner layer of the electrode sheet and the fracture of the outer layer will be aggravated.

[0057] In order to improve the structural stability of the electrode sheet, an embodiment of the present application provides a battery cell, including an electrode assembly, which includes an electrode sheet and multiple bosses; the electrode sheet is a rolled structure; and the multiple bosses are at least partially arranged on the electrode sheet along the rolling direction of the electrode sheet.

[0058] In the electrode sheet provided in the embodiment of the present application, by arranging multiple bosses on the electrode sheet, after the electrode sheet is rolled up, the bosses can play a supporting role between the two adjacent layers of the rolled-up structure, which is beneficial to increase the distance between the two adjacent layers of the rolled-up structure; that is, the multiple bosses can make the two adjacent layers of the rolled-up structure looser, which is beneficial to reduce the occurrence of breakage of the electrode sheet.

[0059] The battery involved in the embodiments of the present application can be used in electrical equipment that uses the battery as a power source, or in various energy storage systems that use the battery as an energy storage element. The electrical equipment may be, but is not limited to, vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and electric tools, etc. The vehicle may be a pure electric vehicle, a hybrid electric vehicle, or an extended-range vehicle, etc. The spacecraft includes an airplane, a rocket, a space shuttle, and a spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc.

[0060] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device in some embodiments of the present application.

[0061] Please refer to Figure 1, which is a schematic diagram of the structure of a vehicle 100 provided in an embodiment of the present application. A battery 110 is provided inside the vehicle 100, and the battery 110 can be provided at the bottom, head, or tail of the vehicle 100. The battery 110 can be used to power the vehicle 100. For example, the battery 110 can serve as an operating power source for the vehicle 100. The vehicle 100 may also include a controller 120 and a motor 130. The controller 120 is used to control the battery 110 to power the motor 130, for example, for starting, navigating, and operating power requirements of the vehicle 100 during driving.

[0062] In some embodiments of the present application, the battery 110 can serve not only as an operating power source for the vehicle 100 , but also as a driving power source for the vehicle 100 , replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 100 .

[0063] Please refer to Figure 2, which is an exploded view of a battery provided in an embodiment of the present application. Battery 110 includes a housing 10, battery cells 20, and a power distribution device. Battery cells 20 are housed within housing 10. Housing 10 provides storage space for battery cells 20 and can have various structures. In some embodiments, housing 10 can include a first portion 11 and a second portion 12, which overlap with each other and together define a storage space for battery cells 20. Second portion 12 can be a hollow structure with one end open. First portion 11 can be a plate-like structure, overlapping the open side of second portion 12, so that the first and second portions 11 and 12 together define a storage space. Alternatively, first portion 11 and second portion 12 can each be a hollow structure with one end open, with the open side of first portion 11 overlapping the open side of second portion 12. Housing 10 formed by first portion 11 and second portion 12 can have various shapes, such as a cylinder or a rectangular parallelepiped. In some embodiments, the box 10 can serve as part of the vehicle body's bottom structure. For example, a portion of the box can form at least a portion of the vehicle body's floor, or at least a portion of the vehicle body's crossbeams and longitudinal beams. The battery 110 can include multiple battery cells 20, which can be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a combination of series and parallel configurations for the multiple battery cells 20.

[0064] In some embodiments, multiple battery cells 20 can be directly connected in series, parallel, or hybrid, and the entire battery cell 20 can then be housed within the housing 10. Alternatively, the battery 110 can be constructed by first connecting multiple battery cells 20 in series, parallel, or hybrid to form a battery module, which is then connected in series, parallel, or hybrid to form a single unit housed within the housing 10. The battery 110 can also include other functional components. For example, the battery 110 can include a busbar for electrically connecting the multiple battery cells 20. 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 may be cylindrical, flat, rectangular, or in other shapes. A secondary battery refers to a battery cell that can be recharged to activate the active material after discharge and continue to be used. A primary battery refers to a battery cell that cannot be recharged to activate the active material after the battery cell's power is exhausted and continues to be used. The battery cell may also be a lithium-ion battery, a sodium-ion battery, a sodium-lithium-ion battery, a lithium metal battery, a sodium metal battery, a lithium-sulfur battery, a magnesium-ion battery, a nickel-hydrogen battery, a nickel-cadmium battery, a lead-acid battery, or the like, but is not limited thereto. The battery cell may be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell, or a battery cell of other shapes. Prismatic battery cells include square-shell battery cells, blade-shaped battery cells, and polygonal prismatic battery cells. Polygonal prismatic battery cells, for example, hexagonal battery cells, are not particularly limited in this application.

[0065] The power distribution device is used to distribute electrical energy to various electrical devices in the vehicle. It can be a high-voltage distribution device, specifically designed to distribute electrical energy to high-voltage devices such as, but not limited to, electric drive units. It can also be a low-voltage distribution device, specifically designed to distribute electrical energy to low-voltage devices such as, but not limited to, the instrument panel, lights, and power seats. The distribution device includes a mounting assembly, which secures the pre-charge resistor.

[0066] In some embodiments, please refer to FIG3 , which shows a schematic structural diagram of an electrode assembly 200 provided in this embodiment. The electrode assembly 200 in this embodiment is a bare cell of a cylindrical battery cell 20. The electrode assembly 200 includes a positive electrode sheet 200a and a negative electrode sheet 200b . The positive electrode sheet 200a and / or the negative electrode sheet 200b are formed by rolling up an electrode sheet 210 . In further embodiments, a separator 300 is disposed between the positive electrode sheet 200a and the negative electrode sheet 200b .

[0067] The battery cell 20 provided in the embodiment of the present application is described below with reference to the accompanying drawings.

[0068] Referring to Figure 3, an embodiment of the present application provides a battery cell 20, including an electrode assembly 200, wherein the electrode assembly 200 includes an electrode sheet 210 and a plurality of bosses 220; the electrode sheet 210 is a winding structure; and the plurality of bosses 220 are at least partially arranged on the electrode sheet 210 along the winding direction a of the electrode sheet 210.

[0069] It is understandable that the electrode sheet 210 can generally be a positive electrode sheet 200a and a negative electrode sheet 200b. The positive electrode sheet 200a is composed of a positive electrode current collector and a positive electrode coating layer; the negative electrode sheet 200b is composed of a negative electrode current collector and a negative electrode coating layer. The main function of the current collector is to carry the electrode active material, collect and output the current generated by the active material, and input the electrode current to the active material. In the technical solution of the embodiment of the present application, the electrode sheet 210 is the positive electrode sheet 200a. The thickness direction can be the direction in which the upper surface of the electrode sheet 210 points to the lower surface when it is in the laying state, or the direction in which the lower surface points to the upper surface.

[0070] Exemplarily, the positive and negative electrode coating layers are composed of active material powder, conductive agent, binder and other additives. Among them, active material refers to the positive electrode material / negative electrode material that participates in the electrochemical oxidation / reduction reaction. The conductive agent collects microcurrent (maintains electrical contact) between the active material particles and between the active material particles and the current collector, thereby improving the electronic conductivity, reducing the contact resistance of the electrode, reducing the electrode polarization, and promoting the infiltration of the electrolyte into the electrode sheet. The binder can bind the active material powder together, enhance the electronic contact between the electrode active material and the conductive agent and between the active material and the current collector, and better stabilize the structure of the electrode sheet.

[0071] It is understood that "the electrode sheet 210 is a retractable structure" means that the electrode sheet 210 can be rolled up to save space. Exemplarily, the electrode sheet 210 is made of a flexible material and can be easily rolled up or folded so that the electrode sheet 210 can be rolled up during the process of making the battery cell. The winding direction a refers to the direction from the beginning of the electrode sheet 210 to the end of the last retraction. Similar to the "tape measure" structure, the tape measure is a retractable structure, and the tape measure is in an extended state during measurement. After the measurement is completed, the tape measure is retracted along its retracting direction a to return to the retracted state. In an embodiment of the present application, the retracting direction a is defined as the length direction c of the electrode sheet 210; that is, the retracting direction a is perpendicular to the thickness direction of the electrode sheet 210. The height of the boss 220 refers to the protruding height of the boss 220 along the thickness direction of the electrode sheet 210.

[0072] In the technical solution of the embodiment of the present application, by arranging multiple bosses 220 on the electrode sheet 210, after the electrode sheet 210 is rolled up, the bosses 220 can play a supporting role between the two adjacent layers of the rolled-up structure, which is beneficial to increase the distance between the two adjacent layers of the rolled-up structure; that is, multiple bosses 220 can be distributed between the two adjacent layers to support the two adjacent layers at multiple points, so that a gap can be formed between the two adjacent layers, which is beneficial to alleviate the extrusion force between the two adjacent layers, and further beneficial to reduce the situation where the electrode sheet 210 is broken due to the extrusion force.

[0073] In some embodiments, referring to FIG. 4 , the retracted structure has an inner layer 213 and an outer layer 214 , and a plurality of bosses 220 are disposed on the inner layer 213 .

[0074] It should be explained that the inner layer 213 refers to one or more layers of the multi-layer structure that are closer to the axis after the electrode sheet 210 is rolled along its axis to form a rolled structure; correspondingly, the outer layer 214 refers to one or more layers of the structure that are farther away from the axis of the rolled structure.

[0075] It is understandable that after the rolled structure is formed, the outer layer 214 squeezes the inner layer 213, causing the distance between the inner layer 213 and the adjacent layers to become smaller, making the inner layer 213 more likely to collapse. In the technical solution of the embodiment of the present application, multiple bosses 220 are provided on the inner layer 213. In this way, the bosses 220 can form a support between the inner layer 213 and its adjacent layers to ensure the distance between the inner layer 213 and the adjacent layers; that is, it can help to make the distance between the inner layer 213 and the adjacent layers of the rolled structure looser, thereby helping to reduce the risk of collapse of the inner layer 213 of the electrode sheet 210.

[0076] In some embodiments, the boss 220 is a deformable structure. Thus, during the formation of the rolled-up structure, the adjacent layers of the inner layer 213 squeeze the boss 220 on the inner layer 213. As the number of rolled-up layers increases, the squeezing force of the adjacent layers on the boss 220 increases. During this process, the boss 220 gradually collapses and deforms, so that the inner layer 213 and its adjacent layers change from being loose to being tight.

[0077] In some embodiments, please continue to refer to FIG. 3 and FIG. 4 , along the rolling direction aa of the electrode sheet 210 , the heights of the plurality of bosses 220 along the thickness direction of the electrode sheet 210 decrease gradually.

[0078] It should be explained that as the number of layers of the rolled-up structure increases, the inner layers of the rolled-up structure are subjected to greater extrusion pressure, and the spacing between the inner layer and its adjacent layers will also decrease. In the technical solution of this embodiment, the height of the boss 220 is set to decrease along the rolling direction a; that is, the height of the boss 220 of the inner layer 213 is greater than the height of the boss 220 of the outer layer 214, and the boss 220 of the inner layer 213 will be subjected to greater extrusion pressure, so the boss 220 of the inner layer 213 will produce greater deformation; by setting the height of the boss 220 of the inner layer 213 to be greater than the height of the boss 220 of the outer layer 214, it is beneficial to ensure that the height of the boss 220 of the inner layer 213 and the boss 220 of the outer layer 214 are consistent after deformation, which is beneficial to ensuring that the tightness of the inner layer 213 and the outer layer 214 is consistent, or the inner layer 213 is looser than the outer layer 214, which is beneficial to reducing the risk of collapse of the inner layer 213 of the electrode sheet 210.

[0079] In some embodiments, please continue to refer to Figure 4; multiple bosses 220 are arranged on the electrode sheet 210 at intervals. In other embodiments, please refer to Figure 5, which shows a schematic structural diagram of the electrode sheet provided by this embodiment; multiple bosses 220 are sequentially connected along the winding direction to form a convex strip structure.

[0080] In some embodiments, referring to FIG. 3 , a plurality of bosses 220 are provided along the winding direction a of the electrode sheet 210 , and the number of bosses 220 is positively correlated with the length of the electrode sheet 210 along the winding direction a. It is understood that the longer the electrode sheet 210 is, the denser the bosses 220 are arranged. As the length of the electrode sheet 210 increases, the number of outer layers of the winding structure increases, and the inner layer is subjected to greater compressive stress. In this embodiment, a sufficient number of bosses 220 are provided along the winding direction a to provide more sufficient support when the inner layer is subjected to greater compressive stress.

[0081] In some embodiments, referring to FIG. 3 , multiple bosses 220 are spaced apart along the winding direction a of the electrode sheet 210. It is understood that the spaced arrangement of the multiple bosses 220 facilitates increasing the space between adjacent layers of the winding structure. In other words, the spaced arrangement of the multiple bosses 220 allows for greater spacing between adjacent layers of the winding structure, thereby reducing the risk of breakage of the electrode sheet 210.

[0082] In some embodiments, referring to FIG. 3 , at least three bosses 220 are provided on each electrode sheet 210 along the winding direction a of the electrode sheet 210 , and the distance between two adjacent bosses 220 gradually increases along the winding direction a of the electrode sheet 210 .

[0083] It should be noted that the increasing distance between adjacent protrusions 220 along the winding direction a of the electrode sheet 210 refers to a decreasing density of the protrusions 220 along the winding direction a. It is understood that the innermost layers of the winding structure experience greater compressive forces, and the spacing between the inner layer 213 and its adjacent layers also decreases. Providing a denser density of protrusions 220 within the inner layer 213 increases the support between the inner layer 213 and its adjacent layers, thereby ensuring the compactness of the inner layer 213.

[0084] In some embodiments, referring to FIG. 7 , FIG. 6 is an enlarged schematic diagram of a portion A of FIG. 5 provided in this embodiment; at least some of the multiple bosses are connected to form convex strips, and the height of the convex strips decreases along the winding direction of the electrode sheet.

[0085] In some embodiments, please refer to Figure 7, which shows a schematic structural diagram of the battery cell 20 provided in this embodiment. The battery cell 20 of this embodiment is a square battery cell. The difference between a square battery cell and a cylindrical battery cell lies in the different structural shapes of the electrode sheet after winding. The electrode sheet of the square battery cell is wound into a runway structure, while the electrode sheet of the cylindrical battery cell is wound into a circular structure. In this embodiment, there are at least three bosses 220, and the distance between two adjacent bosses 220 gradually increases along the winding direction a of the electrode sheet 210.

[0086] In the technical solution of the embodiment of the present application, since the inner layer of the rolling structure formed by the electrode sheet 210 will be subjected to a greater extrusion pressure than the outer layer, the distance between two adjacent bosses 220 in the rolling direction a of the electrode sheet 210 is gradually increased. That is to say, the inner layer of the rolling structure is denser than the outer layer, which is beneficial to offset part of the extrusion force brought to the inner layer by the outer layer, and thus is beneficial to improve the support stability of the inner layer.

[0087] In some embodiments, please continue to refer to Figure 7. The electrode sheet 210 is rolled up to form a rolled structure. The electrode sheet 210 is configured so that when the rolled structure is formed, as the number of layers of the rolled structure increases, the height of the multiple bosses 220 along the thickness direction of the electrode sheet 210 decreases.

[0088] It is understandable that the electrode sheet 210 can form a multi-layer winding structure after being wound up, similar to a tape measure structure. In the technical solution of the embodiment of the present application, as the number of layers of the winding structure increases, the height of the multiple bosses 220 along the thickness direction of the electrode sheet 210 decreases; that is, in different layers, the height of the bosses 220 located in the outer layers is lower, and the height of the bosses 220 located in the inner layers is higher. In this way, it is beneficial to make the inner layer of the winding structure relatively looser, which is beneficial to reducing the risk of collapse of the inner layer of the electrode sheet 210. It can also make the outer layer of the winding structure relatively tighter, which is beneficial to making the structure of the electrode sheet 210 after winding more compact, thereby helping to reduce the space occupied by the electrode assembly 200 structure.

[0089] In some embodiments, the electrode sheet 210 is configured so that, when formed into a rolled-up structure, the bosses 220 in the same layer of the rolled-up structure have the same height. In the technical solution of the embodiment of the present application, for the rolled-up structure after the electrode sheet 210 is rolled up, the same layer is subjected to substantially the same extrusion force, so the bosses 220 in the same layer can be set to the same height.

[0090] In some embodiments, please refer to Figure 8, which shows a structural schematic diagram of the electrode assembly 200 provided in this embodiment. The multiple bosses 220 of this embodiment are arranged along the winding direction a to form a first boss column 240 and a second boss column 250. The first boss column 240 and the second boss column 250 are alternately arranged along the width direction b of the electrode sheet 210, and the bosses in the first boss column 240 and the bosses in the second boss column 250 are staggered in the width direction b.

[0091] It is understood that a boss array refers to a collection of bosses 220 arranged along a specific direction. Thus, by providing the first boss array 240 and the second boss array 250, the spacing between adjacent layers of the rolled-up structure is improved in the width direction b of the electrode sheet 210, thereby improving the structural stability of the rolled-up electrode sheet 210.

[0092] The projection of the boss 220 of the first boss column 240 in the width direction b and the projection of the second boss column 250 in the width direction b are staggered, which is beneficial to improving the supporting stability of the first boss column 240 and the second boss column 250 on other layer structures, and further beneficial to improving the structural stability of the electrode sheet 210 after rolling up.

[0093] In some embodiments, the number of bosses 220 is the same between different columns of bosses 220. In other embodiments, the number of bosses 220 is different between different columns of bosses 220.

[0094] In some embodiments, the bosses in the first boss array 240 and the second boss array 250 are arranged in a grid structure, which helps improve the support stability of the first boss array 240 and the second boss array 250 on other layer structures, thereby improving the structural stability of the electrode sheet 210 after it is rolled up.

[0095] In some embodiments, the shape of the smallest grid unit of the grid structure is an isosceles triangle.

[0096] In some embodiments, please continue to refer to FIG. 8 , the width direction b and the rolling direction a are perpendicular to each other.

[0097] In some embodiments, referring to FIG3 , the boss 220 is formed by providing a groove 230 on one side of the electrode sheet 210. The groove 230 extends along the thickness direction of the electrode sheet 210 to form the boss 220 on the other side of the electrode sheet 210. For example, a pressing roller can be used to press the groove 230 on one side of the electrode sheet 210 while forming the boss 220 on the other side.

[0098] In some embodiments, there are multiple grooves 230, and the grooves 230 are arranged corresponding to the bosses 220. In this way, each boss 220 is formed by pressing the grooves 230, which is conducive to simplifying the processing difficulty.

[0099] In some embodiments, the boss 220 has an abutting surface disposed away from the electrode sheet 210 , and at least a portion of the abutting surface is a curved surface.

[0100] It can be understood that after the rolling structure is formed, the abutment surface of the boss 220 of the inner layer 213 abuts on the plane of the adjacent layer. By setting at least part of the abutment surface as a curved surface, it is beneficial to reduce the pressure of the boss 220 on the other layer of the rolling structure, so as to improve the structural strength of the rolling structure.

[0101] In some embodiments, the curved surface is an arc surface. More specifically, the boss 220 is a portion of the spherical structure formed by cutting along a plane.

[0102] In some embodiments, referring to FIG. 8 , a predetermined region 211 is provided on the electrode sheet 210 for arranging the bosses 220. A spacing region 212 is provided between the boundary of the predetermined region 211 and the boundary of the electrode sheet 210. Thus, by reserving the spacing region 212 for cutting, it is advantageous to prevent additional metal burrs from being generated when cutting the electrode sheet 210. In other words, if the cutting path is set on the bosses 220 when cutting the electrode sheet 210, more metal burrs may be generated.

[0103] In some embodiments, the spacing region 212 between the boundary of the predetermined region 211 and the boundary of the electrode sheet 210 is between 10 mm and 25 mm. Specifically, the width of the spacing region 212 is between 15 mm and 20 mm.

[0104] Referring to Figures 3, 7, and 8, an embodiment of the present application provides a battery cell 20, which includes an electrode assembly 200. The electrode assembly 200 includes an electrode sheet 210 and a plurality of boss columns. The plurality of boss columns 220 are arranged on the electrode sheet 210 along the width direction b of the electrode sheet 210; the boss columns 220 include a plurality of bosses 220 arranged along the length direction c of the electrode sheet 210. Specifically, the bosses 220 are formed by providing a groove 230 on one side of the electrode sheet 210 and a corresponding raised structure on the other side. The height of the plurality of bosses 220 along the thickness direction of the electrode sheet 210 decreases as the electrode sheet 210 is wound in the winding direction a. The side of the boss 220 facing away from the electrode sheet 210 is a partially spherical structure.

[0105] It can be understood that in the embodiment of the present application, after the electrode sheet 210 is rolled up, a rolled structure is formed, and a gap can be formed between two adjacent layers of the rolled structure through the boss 220 to reduce the risk of collapse of the inner layer and the risk of fracture of the outer layer.

[0106] In the second aspect, please refer to FIG9 , which shows a schematic diagram of the steps of the method for preparing the electrode assembly 200 provided in this embodiment. This application also provides a method for preparing a battery cell, which is used to prepare the battery cell of any of the above embodiments; the preparation method includes:

[0107] S100 : providing an electrode sheet 210 ; specifically, a pre-pressing portion is provided on the electrode sheet 210 , and the boss 220 is formed by processing the pre-pressing portion.

[0108] S200: An embossing roller is rolled on one side of the electrode sheet 210 to form a plurality of grooves 230 on the electrode sheet 210, thereby forming a boss 220 on the other side of the electrode sheet 210 away from the grooves 230. The pressure of the embossing roller on the electrode sheet 210 increases or decreases along the direction in which the embossing roller rolls on the electrode sheet 210. Specifically, the pressure is applied toward the pre-pressed portion of the electrode sheet 210 to form a boss 220 on the other side of the electrode sheet 210.

[0109] More specifically, the depth of the grooves 230, and thus the height of the bosses 220, can be adjusted by adjusting the pressure of the embossing roller. For example, increasing the pressure of the embossing roller can produce deeper grooves 230, resulting in taller bosses 220; or decreasing the pressure of the embossing roller can produce shallower grooves 230, resulting in shorter bosses 220.

[0110] In some embodiments, the pressure of the embossing roller can be automatically adjusted by providing an electric proportional valve.

[0111] In some specific embodiments, the battery cell 20 is cylindrical, and the winding structure is wound into a cylindrical structure with a diameter of 46 mm. The first and second bosses are adjacent bosses on the same circle. The angle between the line connecting the first boss and the center of the circle and the line connecting the second boss and the center of the circle is 18°. The height of the boss 220 is 1.3 mm. A 25 mm cylinder is used, and during rolling along the winding direction a, the cylinder pressure is adjusted from a first pressure to a second pressure. The first pressure is between 0.4 MPa and 0.45 MPa, and the second pressure is between 0.27 MPa and 0.32 MPa.

[0112] In some embodiments, pressure sensors are provided at both ends of the embossing roller, and the parallelism of the embossing roller is adjusted by the pressure sensors to ensure the consistency of the height of the boss 220 in the width direction b of the electrode sheet 210 .

[0113] In some embodiments, the battery cell 20 includes a positive electrode sheet 200 a and a negative electrode sheet 200 b , and the positive electrode sheet 200 a and / or the negative electrode sheet 200 b are formed by rolling up the electrode sheet 210 .

[0114] In some embodiments, a separator 300 is disposed between the positive electrode sheet 200a and the negative electrode sheet 200b. The separator 300 acts as an insulator, separating the positive and negative electrodes. This prevents electrons from freely passing through the battery cell 20, thereby preventing short circuits. In one exemplary embodiment, the separator 300 is a porous plastic film that allows lithium ions in the electrolyte to pass freely, forming a circuit between the positive and negative electrodes.

[0115] In a third aspect, the present application further provides a battery 110, which includes the aforementioned battery cell 20. In some embodiments, the battery 110 includes a housing having a plurality of cavities, each of which contains a plurality of battery cells 20.

[0116] In a fourth aspect, the present application further provides an electric device, which includes the above-mentioned battery 110. In some embodiments, the electric device is a vehicle 100.

[0117] 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.

[0118] 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 battery cell comprising an electrode assembly, characterized in that: The electrode assembly comprises: An electrode sheet having a rolled structure; A plurality of bosses are at least partially arranged on the electrode sheet along a winding direction of the electrode sheet.

2. The battery cell according to claim 1, wherein: The retracting structure comprises an inner layer and an outer layer, and a plurality of bosses are arranged on the inner layer.

3. The battery cell according to claim 1 or 2, characterized in that: The boss is a deformable structure.

4. The battery cell according to any one of claims 1 to 3, characterized in that: As the electrode sheet is rolled up, the protrusion heights of the plurality of bosses decrease along the thickness direction of the electrode sheet.

5. The battery cell according to any one of claims 1 to 4, characterized in that: The plurality of bosses are arranged at intervals along the winding direction of the electrode sheet.

6. The battery cell according to claim 5, characterized in that At least three bosses are provided on each layer of the electrode sheet along the winding direction of the electrode sheet, and the distance between two adjacent bosses gradually increases along the winding direction of the electrode sheet.

7. The battery cell according to any one of claims 1 to 6, characterized in that: At least some of the plurality of bosses are connected to form a convex strip, and the protrusion height of the convex strip decreases along the winding direction of the electrode sheet.

8. The battery cell according to any one of claims 1 to 7, characterized in that: The plurality of bosses are arranged along the winding direction to form a first boss column and a second boss column. The first boss column and the second boss column are alternately arranged along the width direction of the electrode sheet. The bosses in the first boss column and the bosses in the second boss column are staggered in the width direction.

9. The battery cell according to claim 8, characterized in that The bosses in the first boss column and the bosses in the second boss column are arranged in a grid structure.

10. The battery cell according to any one of claims 1 to 9, characterized in that: The electrode sheet is configured so that the protrusions in the same layer of the rolled structure have the same protrusion height.

11. The battery cell according to any one of claims 1 to 9, characterized in that: The bosses are arranged on the same side of the electrode sheet, and a groove is provided on the other side of the electrode sheet at a position corresponding to the bosses.

12. The battery cell according to any one of claims 1 to 9, characterized in that: The boss has an abutting surface that is arranged away from the electrode sheet, and at least a portion of the abutting surface is a curved surface.

13. The battery cell according to claim 12, characterized in that The curved surface is an arc surface.

14. The battery cell according to any one of claims 1 to 9, characterized in that: The electrode sheet is provided with a preset area for arranging the bosses, and a spacing area is formed between a boundary of the preset area and a boundary of the electrode sheet.

15. A method for preparing a battery cell, characterized in that: The preparation method comprises: Provide electrode pads; An embossing roller is used to roll on one side of the electrode sheet and press a plurality of grooves on the electrode sheet to form a boss on the other side of the electrode sheet away from the grooves; wherein the pressure of the embossing roller on the electrode sheet increases or decreases along the direction in which the embossing roller rolls on the electrode sheet.

16. The method for preparing a battery cell according to claim 15, characterized in that: The electrode sheet is configured such that, from the inner layer to the outer layer of the rolled structure, the protrusion heights of the plurality of bosses decrease gradually along the thickness direction of the electrode sheet.

17. A battery, characterized in that: The battery comprises the battery cell according to any one of claims 1 to 16.

18. An electrical device, characterized in that: The electric device comprises the battery according to claim 17.

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