Roll member, winding device, electrode core winding method, electrochemical device, and electronic device

Abstract

The application relates to a roller piece, a winding device, an electric core winding method, an electrochemical device and an electronic equipment. The roller piece comprises a roller main body and an acting piece. The acting piece is located on the outer wall of the roller main body and has an acting substance. The acting piece can contact the positive active material of a positive electrode sheet with the acting substance before the positive electrode sheet is wound on a winding shaft.

Description

Technical Field

[0001] This application relates to rollers, winding devices, battery cell winding methods, electrochemical devices, and electronic equipment. Background Technology

[0002] The wound structure is one of the commonly used cell structures for rechargeable batteries, and its advantages are high production efficiency and low cost.

[0003] However, wound-structured battery cells pose safety risks and may even experience short-circuit failures. Summary of the Invention

[0004] In view of the problems existing in the background art, the purpose of this application is to provide a roller, a winding device, a battery cell winding method, an electrochemical device, and an electronic device to solve the safety problems of wound battery cells and improve the reliability of the electrochemical device and the electronic device.

[0005] In a first aspect, this application provides a roller, the roller comprising: a roller body; an actuating member located on the outer wall of the roller body; wherein the actuating member has an actuating substance, the actuating member being capable of contacting the actuating substance with the actuated material before the actuated material is wound onto the winding shaft.

[0006] In the technical solution of this application embodiment, it is easy to change the properties of the wound material. For example, the roller is suitable for the winding device of the wound battery cell. The roller is used to contact the active material of the positive electrode with the positive electrode sheet, thereby increasing the CB value (Cell Balance, which is the ratio of the capacity of the active material of the negative electrode to the capacity of the active material of the positive electrode) at the inner corner of the battery cell. This can effectively avoid the lithium plating problem, solve the safety problem of the wound battery cell, and improve the reliability of electrochemical devices and electronic devices. At the same time, the structure of the roller has little impact on the winding production process, and retains the advantages of high production efficiency and low cost of the wound battery cell.

[0007] In some embodiments, the actuating element includes a first chamber containing the actuating substance, the chamber wall of the first chamber having capillary pores to retain the actuating substance within the first chamber. This capillary structure allows for control over the timing of the actuating substance's contact with the wound material through a simple design.

[0008] In some embodiments, the first chamber has a communication portion for communication with a pressure source. When the pressure source applies pressure to the active substance, the active substance flows out from the capillary to contact the wound material. The structure of using a pressure source to communicate with the first chamber is simple and has minimal impact on the properties of the active substance itself, thus improving the reliability of the active substance's effect on the active material.

[0009] In some embodiments, the shape of the capillary pores is one or more of a circle or a polygon. By flexibly setting the shape of the capillary pores, it can be ensured that the active substance has full contact with the inner corner positions of various areas and shapes.

[0010] In some embodiments, the viscosity of the active substance is 0.5-8 mPa / s, and the active substance within this viscosity range is easily contained in the first chamber.

[0011] In some embodiments, the active substance includes water and one or more N-methylpyrrolidone. These active substances are commonly used in battery cell production and are readily available.

[0012] In some embodiments, the inner and outer walls of the roller body define a second chamber containing the active substance. The second chamber communicates with the first chamber to supply the active substance to the first chamber. This allows the active substance to be stored using the roller body's own structure, facilitating the delivery of the active substance to the first chamber of the active component and improving the integration of the winding device including the roller, resulting in a compact winding device structure.

[0013] In some embodiments, the actuating element includes an adhesive region, the adhesive region being provided with adhesive tape, the adhesive tape including a substrate and an adhesive backing bonded to the substrate, and the actuating substance including the adhesive backing. The adhesive tape structure facilitates arrangement within the roller body, resulting in a simple roller structure.

[0014] In some embodiments, the shape of the roller body is circular or polygonal. By flexibly setting the shape of the roller body, it can be ensured that the shape of the bonding area of ​​the active component matches the shape of the wound battery cell, and the adhesive tape can fully contact the inner corner positions of various areas and shapes.

[0015] In some embodiments, the adhesive backing includes any pressure-sensitive adhesive with a 180-degree planar peel strength > 0.01 N / mm, and the substrate is made of polyethylene terephthalate (PET), polypropylene (PP), or fusible polytetrafluoroethylene (PFA). The above adhesives have good adhesion to the positive electrode active material, and the substrate is low in cost and easy to obtain.

[0016] Secondly, this application provides a winding apparatus, the winding apparatus comprising: a winding shaft for winding a material; a roller as described in the first aspect, wherein the roller is located upstream of the winding shaft; and an intermittent actuation device connected to the roller, such that the actuating element of the roller can intermittently contact the actuating substance with the material before the material is wound onto the winding shaft.

[0017] In the technical solution of this application embodiment, the synergistic effect of the winding shaft, rollers and intermittent actuation device is adopted. The winding device can easily change the properties of the wound material, such as contacting the active material of the positive electrode sheet with the active material, and improve the CB value of the inner corner position of the battery cell. This can effectively avoid the lithium plating problem, solve the safety problem of the wound battery cell, and improve the reliability of electrochemical devices and electronic devices. At the same time, the structure of the rollers has little impact on the winding production process, and retains the advantages of high production efficiency and low cost of the wound battery cell.

[0018] In some embodiments, the winding device includes multiple pressure roller positions, at least one of which corresponds to the roller. This allows the roller to fully utilize the mounting structure of the pressure rollers in the winding device without requiring significant modifications to the original winding device, making the solution easy to implement.

[0019] In some embodiments, the roller is part of the roller described in the first aspect, and the intermittent actuation device includes a position adjustment mechanism capable of intermittently adjusting the position of the roller to contact the adhesive with the wound material to bond a portion of the material of the wound material away from the wound material.

[0020] In some embodiments, the roller is part of the roller described in the first aspect, and the intermittent actuation device includes a pressure source capable of intermittently applying pressure to the active substance, causing the active substance to intermittently flow out from the capillaries to contact the wound.

[0021] Thirdly, this application provides a cell winding method, wherein the cell winding method employs rollers as described in the first aspect to apply the active material of the positive electrode sheet being wound.

[0022] In some embodiments, when the positive electrode sheet being wound corresponds to the inner corner position of the positive electrode sheet, the active material of the roller is in contact with the inner corner position; when the positive electrode sheet being wound corresponds to a position other than the inner corner position of the positive electrode sheet, the active material of the roller is not in contact with the positive electrode sheet. This improves the efficiency of the winding process and minimizes the loss of battery capacity.

[0023] In some embodiments, when the positive electrode being wound is the innermost positive electrode of the battery cell and corresponds to the inner corner position of the innermost positive electrode, the active material of the roller is in contact with the inner corner position; when the positive electrode being wound corresponds to a position other than the inner corner position of the innermost positive electrode, the active material of the roller is not in contact with the positive electrode. This can further improve the efficiency of the winding process and further avoid the loss of battery capacity.

[0024] In some embodiments, the feature is that when the positive electrode sheet being wound corresponds to the inner circle corner position of the positive electrode sheet, the contact time between the active material of the roller and the inner circle corner position is 1s-2min, so as to balance the efficiency of the winding process and the sufficient contact time between the active material and the positive electrode active material of the positive electrode sheet.

[0025] Fourthly, this application provides an electrochemical device, which includes a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode of the electrochemical device has a first positive electrode active material region and a second positive electrode active material region. The activity of the first positive electrode active material region is 0.5%-100% less than the activity of the second positive electrode active material region.

[0026] In the technical solution of this application embodiment, the electrochemical device can effectively avoid the lithium plating problem of wound battery cells, solve the safety problem, and improve the reliability of operation.

[0027] Fifthly, this application provides an electronic device comprising the electrochemical device as described in the fourth aspect.

[0028] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0029] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0030] Figure 1 This is a schematic diagram of a winding device according to one embodiment of this application.

[0031] Figure 2 This is a schematic diagram of a roller according to one embodiment of this application.

[0032] Figure 3 This is a schematic diagram of a winding device according to another embodiment of this application.

[0033] Figure 4 This is a schematic diagram of a winding device according to another embodiment of this application.

[0034] Figure 5This is a schematic diagram of an electrochemical device according to one embodiment of this application.

[0035] Figure label:

[0036] 10 - Winding device;

[0037] 1-Roller, 2-Winding shaft, 3-Intermittent actuation device, 100-Wound object;

[0038] 11-Roller body, 111-Outer wall, 112-Inner wall, 113-Second chamber, 12-Action element, 121-First chamber, 122-Adhesive area, 1210-Capillary, 1220-Adhesive paper, 13-Action substance;

[0039] Positive electrode 4, innermost positive electrode 401, cell 5, negative electrode 6;

[0040] The inner circle corner positions are 40 and 4010, the straight structure parts of the innermost positive electrode plate are 4011 and 4012, the straight structure parts of the cell are 51 and 52, the first positive electrode active material region is 41, and the second positive electrode active material region is 42. Detailed Implementation

[0041] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0043] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0044] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0045] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0046] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0047] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0048] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0049] Currently, the wound structure is one of the commonly used cell structures for rechargeable batteries, with advantages such as fast production efficiency and low cost. However, wound cells pose safety risks and may even experience short-circuit failures.

[0050] The inventors of this application discovered that one of the reasons for the safety risks of wound-type battery cells is that, for wound-type battery cells, the CB value (Cell Balance, which is the ratio of the capacity of the active material of the negative electrode to the capacity of the active material of the positive electrode) at the inner corner position is lower than that at other positions. This makes the part at the inner corner position prone to lithium plating during charging, thus causing safety risks to wound-type battery cells, and even problems such as short circuit failure.

[0051] To address the lithium plating problem at the inner corner of the coiled battery cell, thereby resolving safety issues and improving the performance and reliability of electrochemical and electronic devices, while retaining the advantages of high production efficiency and low cost of coiled cells, the inventors, through in-depth research, designed a roller. By incorporating an active material on the outer wall of the roller body, when the positive electrode being wound corresponds to the inner corner of the positive electrode, the active material contacts the positive electrode active material at the inner corner before the positive electrode is wound onto the winding shaft. This reduces the activity of the positive electrode active material at the inner corner, increasing the CB value at the inner corner, thus effectively preventing lithium plating and resolving the safety issues of coiled batteries, thereby improving the performance and reliability of electrochemical and electronic devices.

[0052] Meanwhile, since existing wound cell winding devices generally have multiple pressure roller structures, the designed rollers can be installed using the existing pressure rollers' corresponding mounting and positioning structures, and can be operated before the positive electrode sheet is wound. This also makes the winding device and winding method using the designed rollers low in cost, while retaining the advantages of high production efficiency and low cost of wound cells.

[0053] The rollers disclosed in this application can be used, but are not limited to, for winding processes of wound cells in lithium-ion batteries, and can also be applied to other winding processes that involve contacting the material with the wound to modify the wound.

[0054] According to some embodiments of this application, refer to Figures 1 to 4 This application provides a roller 1, including a roller body 11 and an actuating member 12. The actuating member 12 is located on the outer wall 111 of the roller body 11, and the actuating member 12 has an actuating substance 13, such as... Figure 1 as well as Figure 3 As shown, the actuating element 12 is able to bring the actuating substance 13 into contact with the winding 100 before the winding 100 is wound onto the winding shaft 2.

[0055] Roller 1 is a roller that can roll, and roller body 11 is a roller-shaped component that can roll around an axis.

[0056] The actuating element 12 refers to the component in the roller 1 that contacts and acts the actuating substance 13 onto the wound material. Compared to the roller body 11 of the roller 1, which is a structural component that realizes the rolling function of the roller 1 itself, the actuating element 12 is a component with a specific function that acts the actuating substance 13 onto the wound material.

[0057] The actuating element 12 is located on the outer wall 111 of the roller body 11, meaning that the actuating element 12 can be... Figure 1 or Figure 3The shown part of the outer wall of the roller body 11 can be provided with a structure such as a notch or groove to provide the action member 12, for example, by interrupting the outline of the outer wall 111. Alternatively, the action member 12 can be provided in a certain area of ​​the outline of the outer wall 111 by superimposing it on the outline of the complete outer wall 111.

[0058] The wound material 100 is generally a strip, such as the positive electrode sheet of a lithium-ion battery. The strip-shaped positive electrode sheet is wound by the winding shaft 2 to form part of the wound cell structure.

[0059] "The winding material 100 is wound before the winding shaft 2" refers to the process of the belt running before the winding material is wound.

[0060] The active substance 13 refers to the substance that changes the properties of certain areas of the wound material 100 upon contact with it. For example, for the positive electrode of a wound battery cell, the active substance can be a substance that reduces the activity of the positive electrode, acting on the inner corner of the positive electrode, thus reducing the capacity of the active material at the inner corner of the positive electrode. The active substance 13 changes the properties of the wound material in various ways, such as physically, for example, by stripping the positive active material of the positive electrode to reduce activity, or chemically, for example, by reacting chemically with the positive active material to reduce the activity of the positive active material of the positive electrode.

[0061] The contact between the active material 13 of the active member 12 and the wound material 100 is such that the active material 13 itself contacts the wound material 100 so that the active material 13 acts on the wound material, without limiting whether the structure of the active member 12 itself contacts the wound material 100.

[0062] By setting the action element 12 and the action substance 13 on the roller 1, it is easy to change the properties of the wound material 100. For example, the roller 1 is suitable for the winding device of the wound battery cell. The action element 12 of the roller 1 is used to contact the action substance 13 with the positive active material of the positive electrode sheet, which improves the CB value at the inner corner position of the battery cell. This can effectively avoid the lithium plating problem, solve the safety problem of the wound battery cell, and improve the reliability of electrochemical devices and electronic devices. At the same time, the roller structure realizes the action of the wound material during the belt carrying process before winding, which has little impact on the winding production process and retains the advantages of high production efficiency and low cost of the wound battery cell.

[0063] According to some embodiments of this application, optionally, please continue to refer to Figure 1 as well as Figure 2 The actuating element 12 includes a first chamber 121, which contains the actuating substance 13. For example... Figure 2As shown, the chamber wall of the first chamber 121 has capillary pores 1210 to retain the active substance 13 inside the first chamber 121.

[0064] The capillary pore 1210 refers to a pore size that, when the active substance 13 is a liquid, is small enough due to capillary action to ensure that the surface tension of the liquid active substance 13 is sufficiently high, thus keeping the active substance 13 within the first chamber 121 at a set temperature or pressure without flowing out. The diameter of the capillary pore 1210 can be 100μm-500μm.

[0065] Through the structure of the capillary pores 1210, the liquid active substance 13 can be kept inside the first chamber 121 without contacting the wound material 100 when the simple structure is not required. When the wound material 100 is wound to the area where the properties need to be changed, the active substance 13 is then brought into contact with the wound material 100, thus accurately controlling the timing of the active substance contacting the wound material.

[0066] According to some embodiments of this application, optionally, the first chamber 121 has a communication portion for communication with a pressure source. When the pressure source applies pressure to the first chamber 121, the active substance 13 flows out from the capillary pore 1210 to contact the wound material 100.

[0067] The connecting portion of the first chamber 121 refers to a component or structure that connects to the pressure source, such as a hole or pipe structure. The pressure source refers to an object that can apply pressure to a material, such as a pneumatic cylinder or a hydraulic cylinder. Due to the pressure from the pressure source, the active substance 13, which was originally contained in the first chamber 121 by capillary action through the capillary pores 1210, can flow out from the capillary pores 1210 and come into contact with the wound material 100.

[0068] The active substance 13 is released from the first chamber 121 by applying pressure. The structure is simple and has little impact on the properties of the active substance itself, thus improving the reliability of the active substance's effect on the wound material.

[0069] According to some embodiments of this application, optionally, the shape of the capillary pore 1210 is circular or polygonal, or one or more. (See reference...) Figure 2 As shown, the shape of the capillary pores 1210 can be entirely circular. However, they can also be polygonal, or some pores can be circular and some can be polygonal.

[0070] The term "polygon" here is used in a broad sense. It includes both planar figures composed of three or more line segments connected end to end, such as triangles, squares, rectangles, and trapezoids, and figures composed of curved and straight line segments, such as sectors. By flexibly setting the shape of the capillaries, it is possible to ensure that the active material can make full contact with the areas of the wound material of various sizes and shapes, such as the inner corners of the positive electrode, avoiding dead zones where the active material cannot reach certain edges.

[0071] According to some embodiments of this application, optionally, the viscosity of the active substance 13 is 0.5-8 mPa / s.

[0072] Viscosity, also known as viscosity coefficient, is a physical quantity that measures the viscosity of a fluid. In a fluid, two parallel liquid layers separated by a distance dx have a velocity gradient dv / dx perpendicular to the flow direction due to internal friction. When the velocity gradient is 1 unit, the viscous force F (also known as internal friction force) generated on the contact surface S of the adjacent layers...

[0073] The pore size of the capillary pore 1210 corresponding to the active substance with the above viscosity range is easy to process, so that the active substance 13 can be easily contained in the first chamber 121.

[0074] According to some embodiments of this application, optionally, the active ingredient 13 includes one or more of water and N-methylpyrrolidone (NMP). Here, "multiple" means that the active ingredient 13 may simultaneously contain water and N-methylpyrrolidone. The active ingredient 13 with the above components is a commonly used material in the production of secondary battery cells. For example, N-methylpyrrolidone is a polar solvent and is commonly used as a dispersant in secondary battery production, thus it is readily available. Water is also the most common raw material used in production. Therefore, using the active ingredient 13 with the above components can achieve the effect of weakening the activity of the positive electrode active material of the positive electrode sheet, while also keeping material costs low.

[0075] According to some embodiments of this application, optionally, reference is made to... Figure 1 As shown, the inner wall 112 and the outer wall 111 of the roller body 11 define a second chamber 113, which contains an active substance 13. The second chamber 113 is connected to the first chamber 121 to supply the active substance 13 to the first chamber 121.

[0076] The inner wall 112 of the roller body 11 refers to the wall surface of the inner ring of the roller-shaped roller body 11. The structure between the inner wall 112 and the outer wall 111 is a cavity, defining the second chamber 113. The second chamber 113 contains the active substance 13 and serves as a storage container for the active substance 13 in the first chamber 121. The structure connecting the second chamber 113 and the first chamber 121 can be a hole or a pipe structure. Unlike the capillary pore 1210, the diameter of the hole connecting the second chamber 113 and the first chamber 121 should be large enough to overcome capillary action and allow the active substance 13 to flow smoothly from the second chamber 113 into the first chamber 121.

[0077] In this way, the active substance 13 can be stored by the structure of the roller body 11 itself, which facilitates the delivery of the active substance to the first chamber 121 of the active component, ensuring a sufficient supply of the active substance 13. This eliminates the need to frequently add the active substance 13 to the active component 12, thereby improving the operating efficiency of the roller 1. In addition, there is no need to set up a storage device and a transport mechanism for the active substance 13 outside the roller 1, which improves the integration of the winding device including the roller 1 and makes the winding device structure compact.

[0078] According to some embodiments of this application, optionally, reference is made to... Figure 3 as well as Figure 4 As shown, the active component 12 includes an adhesive area 122, the adhesive area 122 is provided with adhesive tape 1220, the adhesive tape 1220 includes a substrate and an adhesive backing bonded to the substrate, and the active substance 13 includes the adhesive backing.

[0079] The bonding area 122 refers to the area of ​​the actuating member 12 used to set the adhesive tape 1220. The width of the adhesive tape 1220 can be 1mm-2mm, and its function is to bond and peel off the material in a certain area of ​​the wound material 100. For example, the positive active material at the inner corner of the positive electrode sheet is bonded to the adhesive tape 1220 and removed from the positive electrode sheet. The substrate of the adhesive tape 1220 can be bonded to the bonding area 122 of the actuating member 12, while the adhesive backing of the adhesive tape 1220 is located on the outer surface of the roller 1. After the adhesive backing comes into contact with the positive active material, it peels the positive active material from the positive electrode sheet, thereby reducing the activity of the corresponding position of the positive electrode sheet.

[0080] The use of adhesive tape 1220 facilitates its arrangement within the roller body 11, simplifying the structure of the roller 1. (Comparison) Figure 1 as well as Figure 2 The structure shown uses a first chamber 121 to contain the active substance 13. The structure using adhesive paper only requires setting an adhesive area. The adhesive area can even be a part of the roller-shaped outline of the roller body 11 directly, without the need to specially construct the first chamber and the corresponding capillary structure.

[0081] It is understandable. Figure 1as well as Figure 2 , Figure 3 as well as Figure 4 Although the roller 12 is shown to have either a first chamber 121 with capillary pores 1210 or a structure with adhesive area 122 and adhesive tape 1220, it does not mean that the two structures can only be selected to be present in one roller 1. For example, the same roller 1 can have both structures. For example, the roller 1 can be provided with a first chamber 121 with capillary pores 1210 and a structure with adhesive area 122 and adhesive tape 1220 in the circumferential direction to form the working member 12.

[0082] According to some embodiments of this application, optionally, reference is made to... Figure 3 as well as Figure 4 As shown, the roller body 11 is circular or polygonal in shape. Here, "polygon" is used in a broad sense, encompassing both planar figures composed of three or more line segments connected end-to-end (e.g., triangles, squares, rectangles, trapezoids) and figures composed of curved and straight lines (e.g., sectors). By flexibly setting the shape of the roller body 11, the shape of the bonding area of ​​the active component can be matched to the shape of the wound battery cell. The adhesive tape 1220 can then effectively adhere to the inner corner positions requiring action, ensuring full contact with the positive electrode active material for bonding and peeling.

[0083] According to some embodiments of this application, optionally, the adhesive backing includes any pressure-sensitive adhesive with a 180° planar peel strength > 0.01 N / mm, and the substrate material is polyethylene terephthalate (PET), polypropylene (PP), or fusible polytetrafluoroethylene (PFA).

[0084] The performance of 180° planar peel strength > 0.01 N / mm is tested according to the People's Republic of China National Standard GB2792-1998 "Test Method for 180° Peel Strength of Pressure-Sensitive Adhesive Tapes". The substrate material can be any of polyethylene terephthalate (PET), polypropylene (PP), or fusible polytetrafluoroethylene (PFA).

[0085] Through in-depth research, the inventors discovered that the adhesive with the above performance parameters can effectively peel the positive electrode active material from the inner corner of the positive electrode sheet. The material of the above substrate is low in cost and easy to obtain.

[0086] According to some embodiments of this application, such as Figure 1 as well as Figure 3As shown, this application also provides a winding device 10, including a roller 1, a winding shaft 2, and an intermittent actuation device 3. The roller 1 is the roller described in any of the above embodiments, the winding shaft 2 is for winding the material 100, the roller 1 is located upstream of the winding shaft 2, and the intermittent actuation device 3 is connected to the roller 1, so that the actuating element 13 of the roller 1 can intermittently contact the actuating substance 13 with the material before the positive electrode sheet is wound onto the winding shaft.

[0087] Roller 1 is located upstream of winding shaft 2. That is, roller 1 is the component corresponding to the previous process of winding shaft 2. The contact between roller 1 and the wound material 100 is the previous process step before the wound material 100 is wound on winding shaft 2. Specifically, for the positive electrode sheet, during the tape feeding process before winding on winding shaft 2, it will first pass through roller 1 and contact the active material 13.

[0088] Intermittent actuation device 3, where "intermittent" is the opposite of "continuous", means that the action of intermittently causes the actuating element 12 to also act intermittently on the wound material 100, and the acting substance 13 to intermittently contact the wound material 100, while the non-acting element 12 continues to act on the wound material 100 during the winding process, and the deactivated substance continues to contact the wound material 100.

[0089] The winding device 10 facilitates the modification of the properties of the wound material, such as for winding of wound cells. The rollers are used to bring the active material into contact with the positive electrode active material of the positive electrode sheet, thereby increasing the CB value (Cell Balance, which is the ratio of the capacity of the active material of the negative electrode to the capacity of the active material of the positive electrode) at the inner corner of the cell. This effectively avoids lithium plating problems, thus solving the safety issues of wound cells and improving the reliability of electrochemical devices and electronic devices. At the same time, the winding device retains the advantages of high production efficiency and low cost of the existing winding process.

[0090] According to some embodiments of this application, optionally, the winding device 10 includes a plurality of pressure roller positions P1, P2, and at least one of the plurality of pressure roller positions P1, P2 is provided with a corresponding roller 1.

[0091] The pressure roller position refers to the location in the winding device where the pressure roller is set, for example... Figure 1 , Figure 3 As shown, the winding device includes two pressure roller positions P1 and P2. The pressure rollers here refer to those used in existing winding devices. Pressure roller position P1 is equipped with a pressure roller, while pressure roller position P2 is equipped with roller 1. It can be understood that... Figure 1 , Figure 3 The two pressure roller positions shown are merely an example; the winding device 10 may include a greater number of pressure roller positions.

[0092] This allows roller 1 to make full use of the existing winding device, the corresponding pressure roller position, and the installation accessories, without requiring major modifications to the existing winding device, making the solution easy to implement.

[0093] According to some embodiments of this application, optionally, roller 1 may be... Figure 3 as well as Figure 4 In the example embodiment, the roller 1, i.e. the action member 12 of the roller 1 includes an adhesive area 122 and an embodiment in which adhesive paper 1220 is provided, the corresponding intermittent actuation device 3 includes a position adjustment mechanism, which can intermittently adjust the position of the roller 1 so that the adhesive backing of the adhesive paper 1220 contacts the wound material 100 to bond part of the material of the wound material away from the wound material.

[0094] The position adjustment mechanism can be a position adjustment mechanism for the roller body 11, which displaces the roller 1 as a whole, causing the roller body 11 and the actuating element 12 to separate, for example... Figure 1 The roller body 11 shown moves from position P3 to position P4 along the arrow. When the roller body 11 is at position P3, the roller body 11 is not in contact with the wound material 100, and the adhesive tape 1220 provided on the actuating member 12 is in contact with the wound material 100. When the roller body 11 is at position P4, both the roller body 11 and the adhesive tape 1220 of the actuating member 12 are not in contact with the wound material 100. Alternatively, the position adjustment mechanism can also be a rotational position adjustment mechanism for the actuating member 12, for example... Figure 1 As shown, the roller body 11 is held at position P3, while the actuating member 12 rotates from the first circumferential position A1 to the circumferential position A2 in the direction of the arrow. When the actuating member 12 is at the circumferential position A1, the roller body 11 is not in contact with the wound object 100, and the adhesive paper 1220 provided on the actuating member 12 is in contact with the wound object 100. When the actuating member 12 is at the circumferential position A2, the actuating member 12 is not in contact with the wound object 100, and the roller body 11 is in contact with the wound object 100. At this time, it can continue to act as a pressure roller similar to that of the prior art on the wound object 100.

[0095] The position adjustment mechanism can be used to intermittently adjust the position of the roller 1 so that the backing adhesive contacts the wound material 100 to bond part of the material of the wound material away from the wound material, for example, intermittently bonding the positive electrode sheet to bond the positive active material at the inner corner of the positive electrode sheet.

[0096] According to some embodiments of this application, optionally, roller 1 may be... Figure 1 as well as Figure 2The roller 1 shown in the example embodiment includes an action member 12 of the roller 1 that includes a first chamber 121 containing an action substance 13. The corresponding intermittent actuation device 3 includes the pressure source described above, which can intermittently apply pressure to the action substance 13, so that the action substance 13 intermittently flows out from the capillary pore 1210 to contact the wound material 100.

[0097] Intermittent pressure application refers to intermittently increasing the pressure of the active substance 13 and then reducing it. Taking water or N-methylpyrrolidone as an example, when the positive electrode sheet, which serves as the winding material 100, is located at the inner corner position, the pressure source increases the pressure to greater than 0.2 MPa, causing the active substance 13 to flow out from the capillary pore 1210 and contact the positive electrode active material at the inner corner position. When the positive electrode sheet is in other positions, the pressure returns to the default value, so that the active substance 13 is kept inside the first chamber 121 by the action of the capillary pore 1210 and does not flow out, thereby accurately controlling the pressure.

[0098] It is understandable that, for Figure 1 , Figure 2 In an example embodiment, the intermittent actuation device 3 may further include the position adjustment device described above. When the pressure source increases the pressure, the roller body 11 is located at position P5, and when the pressure source returns to normal pressure, the roller body 11 is located at position P6; or, the roller body 11 remains at position P5, and when the pressure source increases the pressure, the actuating member 12 is located at circumferential position A3, and when the pressure source returns to normal pressure, the actuating member 12 is located at circumferential position A4. At this time, the roller body 11 is in contact with the wound material 100, and can continue to act as a pressure roller similar to that of the prior art on the wound material 100.

[0099] According to some embodiments of this application, this application also provides a method for winding battery cells, see reference. Figure 1 , Figure 3 Using any of the above schemes, the roller 1 is used to apply the active substance 13 to the wound material.

[0100] Optionally, reference may continue to be made to some embodiments of this application. Figure 1 , Figure 3 and combined Figure 5 For a positive electrode 4, when the positive electrode 4 being wound corresponds to the inner corner position 40 of the positive electrode 4, the active material 13 is in contact with the inner corner position 40; when the positive electrode 4 being wound corresponds to a position other than the inner corner position 40 of the positive electrode 4, the active material 13 is not in contact with the positive electrode 4.

[0101] The inner corner position 40 refers to the connection point formed by the winding of the positive electrode sheet. For example, in the square cell structure shown in Figure 5, the inner corner position 40 is the connection point connecting the two straight structural parts 51 and 52 of cell 5. Other positions besides the inner corner position 40 of the positive electrode sheet, for example... Figure 5 As shown, the two straight structural sections 51 and 52 are the positions other than the inner corner position 40 of the positive electrode plate.

[0102] In the cell winding process, roller 1 is used to contact the active material 13 with the positive electrode 4 located at the inner corner position 40, so as to improve the CB value at the inner corner position of the cell, effectively avoid the lithium plating problem, solve the safety problem of the wound cell, and at the same time, retain the advantages of high production efficiency and low cost of the winding process.

[0103] Optionally, reference may continue to be made to some embodiments of this application. Figure 5 When the innermost positive electrode 4 of the battery cell is the innermost positive electrode 401, and the inner corner position 4010 of the innermost positive electrode 401 is corresponding to the inner corner position 4010, the active material 13 is in contact with the inner corner position 4010; when the innermost positive electrode 4 is the position other than the inner corner position 4010 of the innermost positive electrode 401, the active material 13 is not in contact with the positive electrode 4.

[0104] The innermost positive electrode plate is 401, for example. Figure 5 The image shown refers to the innermost positive electrode layer in a structure comprising multiple positive electrode layers 401 and 402. This includes all positions except the inner corner 4010 of the innermost positive electrode layer 401, including the straight structural portions 4011 and 4012 of the innermost positive electrode layer 401, and also any position of the electrode layer 402 other than the innermost positive electrode layer 401. Figure 5 The multi-layer structure shown is just an example; the number of electrode layers in a battery cell can be much greater.

[0105] This improves the efficiency of the winding process. The principle behind this is that, through in-depth research, the inventors discovered that lithium plating is most severe in the innermost layer of wound battery cells. For some wound battery cells, solving the lithium plating problem in the innermost layer is sufficient to resolve the overall lithium plating issue. Therefore, during winding, only the innermost positive electrode needs to contact the active material 13; the other positive electrode layers do not require contact, thus improving the efficiency of the winding process.

[0106] According to some embodiments of this application, optionally, when the positive electrode sheet being wound corresponds to the inner circle corner position of the positive electrode sheet, the interaction time between the active substance 13 and the inner circle corner position is 1s-2min.

[0107] The contact time refers to the time during which the action element 12 provides contact between the action substance 13 and the inner corner position, for example, for Figure 1 , Figure 2 As shown in the embodiment, the active substance 13 flows from the capillary 1210 out of the first chamber 121 to the positive electrode plate within a time range of 1 second to 2 minutes. For example, for... Figure 3 , Figure 4 In the embodiment shown, the adhesive paper 1210 with the active substance 13 is bonded to the positive electrode sheet in a time range of 1 second to 2 minutes, so as to balance the efficiency of the winding process and the sufficient contact time between the active substance and the positive electrode active material of the positive electrode sheet.

[0108] According to some embodiments of this application, this application also provides an electrochemical device, such as... Figure 5 The example includes a positive electrode 4 and a negative electrode 6. The positive electrode active material of the positive electrode 4 has a first positive electrode active material region 41 and a second positive electrode active material region 42. The activity of the first positive electrode active material region 41 is 0.5%-100% less than the activity of the second positive electrode active material region 42.

[0109] Electrochemical devices can be Figure 5 The example of a wound cell can also be a battery including the cell or a battery module consisting of multiple cells.

[0110] The positive electrode active material of the positive electrode sheet 4 has a first positive electrode active material region 41 and a second positive electrode active material region 42, which can be achieved by the winding method described in the above embodiments. That is, the first active material region 42 is located at the inner corner position, and the second active material region 42 is located at other positions. In the winding process, the roller 1 is used to peel off the positive electrode active material at the inner corner position, for example, by using a deactivating substance 13, or by adding a deactivating substance 13 to the inner corner position to reduce the activity of the positive electrode active material at the inner corner position. The activity of the first positive electrode active material region 41 is 0.5%-100% less than the activity of the second positive electrode active material region 42, which means that under the condition of equal area, the capacity of the first positive electrode active material region 41 is 0.5%-100% less than the capacity of the second positive electrode active material region 42.

[0111] The manufacturing process of battery cells may include:

[0112] Preparation of positive and negative electrode sheets: The positive electrode active material is mixed with a certain proportion of carbon black and a certain proportion of binder in a certain medium, and then uniformly coated onto both sides of the positive electrode current collector. The negative electrode active material is mixed with a certain proportion of carbon black and a certain proportion of binder in a certain medium, and then uniformly coated onto both sides of the negative electrode current collector.

[0113] For the prepared positive electrode sheet, the winding method described in the above embodiments is used during each winding of the bare cell, and roller 1 is used to contact the positive electrode sheet, thereby reducing the activity at the corner position of the positive electrode sheet.

[0114] Separator preparation method: The separator is prepared by dry process using PP material or wet process using PE material, and a highly crystalline oriented film is obtained after high-temperature annealing. This film is first stretched at low temperature to form micro-defects, and then the defects are pulled apart at high temperature to form micropores.

[0115] Electrolyte composition: The electrolyte components include lithium salt (which may be one or more of lithium hexafluorophosphate, lithium borate, and lithium perchlorate), organic solvent (which may be cyclic carbonate or chain carbonate), and functional additives (which may be unsaturated carbon compounds, sulfur-containing organic compounds, or halogen-containing compounds).

[0116] Finally, the bare cells that have passed through roller 1 are shaped, assembled, encased, injected with electrolyte, formed, and aged to produce finished hard-shell cells.

[0117] The electrochemical device with the above structure can effectively avoid lithium plating, thus solving the safety issues of wound battery cells and improving the reliability of the electrochemical device.

[0118] According to some embodiments of this application, this application also provides an electronic device that includes the electrochemical device described above.

[0119] Electronic devices include, but are not limited to, mobile digital devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems (such as large electrical cabinets, household uninterruptible power supplies, etc.), etc.

[0120] In optional examples, the electronic device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of this electronic device, a battery pack or battery module can be used.

[0121] Another example of an electronic device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use rechargeable batteries as their power source.

[0122] According to an embodiment of this application, see Figure 1 as well as Figure 2This application provides a roller 1, which includes a roller body 11 and an actuating element 12. The actuating element 12 is a functional plug, including a first chamber 121 with a cavity structure. The first chamber 121 is filled with a deactivating substance 13 of a functional solution that reduces the positive electrode activity. The first chamber 121 has capillary pores 1210. During the winding process of each battery cell, a timed contact of 1s-2min is performed at the corresponding position of the inner corner of the positive electrode sheet, and the pressure on the deactivating substance 13 is increased to >0.2MPa, so that the deactivating substance 13 of the functional solution that reduces the positive electrode activity is squeezed out, contacts the positive electrode active material of the positive electrode sheet, and reduces the positive electrode activity by 0.5% to 100%.

[0123] According to another embodiment of this application, participating Figure 3 as well as Figure 4 The active component 12 is an adhesive area 122 with a block of adhesive tape 1220 for placement. During the winding process of each battery cell, a timed contact of 1 second to 2 minutes is performed at the corresponding position of the inner corner of the positive electrode sheet. The powder of the positive electrode active material of the positive electrode sheet will adhere to the adhesive roller, thereby reducing the active material of the positive electrode sheet and reducing the activity at the corner position by 0.5% to 100%. A receiving device can also be provided in the winding device to collect waste adhesive tape.

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A roller for a winding device, characterized in that, include: A roller body, the roller body being able to rotate about its own axis; The actuating element is located on the outer wall of the roller body; The active element has an active substance, which is capable of contacting the active substance with the positive electrode active material of the positive electrode sheet before the positive electrode sheet is wound onto the winding shaft, so as to reduce the activity of the positive electrode active material.

2. The roller as described in claim 1, characterized in that, The active ingredient includes a first chamber containing the active substance, the chamber wall of the first chamber having capillary pores to retain the active substance within the first chamber.

3. The roller as described in claim 2, characterized in that, The first chamber has a communication portion for communicating with a pressure source. When the pressure source applies pressure to the active substance, the active substance flows out from the capillary to contact the positive electrode sheet.

4. The roller as described in claim 2, characterized in that, The shape of the capillary pores can be circular or polygonal, or one or more.

5. The roller as described in claim 2, characterized in that, The viscosity of the active substance is 0.5-8 mPa·s.

6. The roller as described in claim 2, characterized in that, The active substance includes water and one or more N-methylpyrrolidone.

7. The roller as described in claim 2, characterized in that, The inner and outer walls of the roller body define a second chamber, which contains the active substance and communicates with the first chamber to supply the active substance to the first chamber.

8. The roller as described in claim 1, characterized in that, The active component includes an adhesive area, the adhesive area is provided with adhesive tape, the adhesive tape includes a substrate and an adhesive backing bonded to the substrate, and the active substance includes the adhesive backing.

9. The roller as described in any one of claims 1-8, characterized in that, The shape of the roller body is circular or polygonal.

10. The roller as described in claim 8, characterized in that, The adhesive backing includes any pressure-sensitive adhesive with a 180-degree planar peel strength > 0.01 N / mm, and the substrate is made of polyethylene terephthalate, polypropylene, or fusible polytetrafluoroethylene.

11. A winding device, characterized in that, include: A winding shaft for winding the positive electrode sheet; The roller as described in any one of claims 1-10, wherein the roller is located on the upstream side of the winding shaft; An intermittent actuation device, connected to the roller, enables the actuating element of the roller to intermittently contact the active material of the positive electrode sheet with the active material of the positive electrode sheet before the positive electrode sheet is wound onto the winding shaft, thereby reducing the activity of the positive electrode active material.

12. The winding apparatus as claimed in claim 11, wherein the winding apparatus comprises a plurality of pressure roller positions, characterized in that, The roller is provided at at least one of the multiple pressure roller positions.

13. A winding device, characterized in that, include: A winding shaft for winding the positive electrode sheet; The roller as claimed in claim 8 or 10, wherein the roller is located upstream of the winding shaft; An intermittent actuation device is connected to the roller, such that the actuating element of the roller can intermittently contact the active material of the positive electrode sheet with the active material of the positive electrode sheet before the positive electrode sheet is wound onto the winding shaft, so as to reduce the activity of the positive electrode active material. The intermittent actuation device includes a position adjustment mechanism that can intermittently adjust the position of the roller to contact the backing adhesive with the positive electrode sheet so as to bond part of the material of the positive electrode sheet away from the positive electrode sheet.

14. A winding device, characterized in that, include: A winding shaft for winding the positive electrode sheet; The roller as described in any one of claims 2-7, wherein the roller is located on the upstream side of the winding shaft; An intermittent actuation device is connected to the roller, such that the actuating element of the roller can intermittently contact the active material of the positive electrode sheet with the active material of the positive electrode sheet before the positive electrode sheet is wound onto the winding shaft, so as to reduce the activity of the positive electrode active material. The intermittent actuation device includes a pressure source capable of intermittently applying pressure to the active substance, causing the active substance to intermittently flow out from the capillary to contact the positive electrode.

15. A method for winding a battery cell, characterized in that, Using the roller as described in any one of claims 1-10, the active substance is applied to the positive electrode active material of the wound positive electrode sheet to reduce the activity of the positive electrode active material.

16. The cell winding method as described in claim 15, characterized in that, When the positive electrode sheet being wound corresponds to the inner corner position of the positive electrode sheet, the active material is in contact with the inner corner position; when the positive electrode sheet being wound corresponds to a position other than the inner corner position of the positive electrode sheet, the active material is not in contact with the positive electrode sheet.

17. The cell winding method as described in claim 16, characterized in that, When the positive electrode being wound is the innermost positive electrode of the battery cell and corresponds to the inner corner position of the innermost positive electrode, the active material is in contact with the inner corner position; when the positive electrode being wound corresponds to a position other than the inner corner position of the innermost positive electrode, the active material is not in contact with the positive electrode.

18. The cell winding method as described in claim 16 or 17, characterized in that, When the positive electrode sheet being wound corresponds to the inner corner position of the positive electrode sheet, the interaction time between the active material and the inner corner position is 1 second to 2 minutes.

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