Electrode unit, battery cell, battery, electrical equipment, winding device and method

Abstract

This application relates to an electrode unit, a battery cell, a battery, an electrical device, a winding device and a method, which belong to the field of battery technology. The electrode unit includes a first electrode sheet and a second electrode sheet having opposite polarities, the first electrode sheet and the second electrode sheet are stacked and wound in a winding direction to form the electrode unit, the first electrode sheet includes a first segment and a second segment, a first active material layer is disposed in the first segment, a second active material layer is disposed in the second segment, and the first segment is located upstream of the second segment in the winding direction from the inside to the outside. The electrode unit can be divided into segments and differentiated according to performance requirements, so that different performance requirements can be met.

Description

[Technical Field]

[0001] The present application belongs to the field of battery technology, and in particular relates to an electrode unit, a battery cell, a battery, an electrical device, a winding device and a method.

[0002] Cross-reference to related applications This application claims priority from a Chinese application filed on March 31, 2022, entitled "Electrode unit, battery cell, battery, electrical equipment, winding device and method," with application number 202210335343.8, the entire contents of which are incorporated herein by reference. [Background technology]

[0003] Energy conservation and emission reduction are key to the sustainable development of the automotive industry. Electric vehicles, with their energy-saving and environmental protection advantages, are an important part of this sustainable development. Battery technology is also a key factor in the development of electric vehicles.

[0004] A battery includes at least one battery cell with an electrode unit, which is typically formed by winding a positive electrode sheet and a negative electrode sheet. The performance of the electrode unit depends on the performance of the electrode sheet. Conventionally, the performance of electrode units has been poor, making it difficult to differentiate them. Summary of the Invention

[0005] The present application aims to provide an electrode unit, a battery cell, a battery, an electrical device, a winding device and a method, which can be handled according to performance requirements and can satisfy different performance requirements.

[0006] This application is realized by the following technical solutions.

[0007] In a first aspect, the present application provides an electrode unit, comprising a first electrode sheet and a second electrode sheet having opposite polarities, the first electrode sheet and the second electrode sheet being stacked and wound in a winding direction to form the electrode unit, the first electrode sheet including a first segment and a second segment, a first active material layer disposed in the first segment, a second active material layer disposed in the second segment, and the first segment being located upstream of the second segment in the winding direction from the inside to the outside.

[0008] In the electrode unit of the embodiment of the present application, the first electrode sheet includes a first segment and a second segment, and the first segment is located upstream of the second segment in the winding direction from the inside to the outside. By dividing the first electrode sheet into the first segment and the second segment, different treatments are applied to the first segment located in the inner layer and the second segment located in the outer layer, so that the first segment and the second segment have different physical or chemical properties. This differentiation between the inside and outside allows the performance of the electrode unit to be better adjusted to meet different usage requirements.

[0009] In some embodiments of the present application, the coating density of the first active material layer is different from the coating density of the second active material layer.

[0010] In the above technical solution, the coating density of the first active material layer is made different from that of the second active material layer, thereby adjusting the energy density of the electrode unit and meeting different requirements for the energy density of the electrode unit.

[0011] In some embodiments of the present application, the coating density of the first active material layer is lower than the coating density of the second active material layer.

[0012] In the above technical solution, by making the coating density of the first active material layer lower than that of the second active material layer, the fracture toughness of the first segment is greater than that of the second segment, making cracks or breaks less likely to occur at the curved portion of the first segment, thereby reducing the incidence of cracks or breaks in the first electrode sheet and improving the safety of the battery cell composed of the electrode unit.

[0013] In some embodiments of the present application, the ratio of the thickness of the first active material layer to the thickness of the second active material layer is 1 / 2-3 / 2.

[0014] In the above technical solution, if the coating density of the first active material layer is smaller than the coating density of the second active material layer and the ratio of the thickness of the first active material layer to the thickness of the second active material layer satisfies the above range, it can ensure that the first segment and the second segment are smoothly connected, prevent the active material from falling off or being scratched, and maintain the quality of the electrode unit.

[0015] In some embodiments of the present application, the active material of the first active material layer is the same as or different from the active material of the second active material layer.

[0016] In the above technical solution, by making the active material of the first active material layer different from the active material of the second active material layer, the performance of the first segment and the second segment can be adjusted so that the electrode unit has different physical or chemical performance.

[0017] In some embodiments of the present application, in the winding direction from the inside to the outside, the tail portion of the first segment and the head portion of the second segment are connected, or a gap is provided between the tail portion of the first segment and the head portion of the second segment.

[0018] In the above technical solution, when the tail portion of the first segment and the head portion of the second segment are connected, the continuity of the first electrode sheet can be ensured, and since the first electrode sheet contains more active material, the electrode unit can have a higher energy density. If a gap is provided between the tail portion of the first segment and the head portion of the second segment, the first and second segments can be easily processed, thereby reducing the difficulty of manufacturing the first electrode sheet.

[0019] In some embodiments of the present application, the first electrode sheet further includes a first current collector, and the first active material layer and the second active material layer are respectively disposed on the first current collector.

[0020] In some embodiments of the present application, the first electrode sheet further comprises a first current collector segment and a second current collector segment, the first active material layer being disposed on the first current collector segment to form the first segment, and the second active material layer being disposed on the second current collector segment to form the second segment.

[0021] In the above technical solution, the first active material layer is disposed on the first current collector segment to form the first segment, and the second active material layer is disposed on the second current collector segment to form the second segment, which makes it easy to manufacture the first segment and the second segment.

[0022] In some embodiments of the present application, the tail portion of the first segment and the head portion of the second segment are connected at a first connecting portion.

[0023] In the above technical solution, by connecting the first segment and the second segment at the first connection part, the first segment and the second segment can be positioned relative to each other, preventing displacement of the first segment and the second segment. When the first segment is wound, the first segment drives the second segment via the first connection part, providing the second segment with the driving force required for winding, thereby realizing sequential winding of the first segment and the second segment.

[0024] In some embodiments of the present application, the electrode unit further includes a separator that separates the first electrode sheet and the second electrode sheet.

[0025] In the above technical solution, the separator separates the first and second electrode sheets, thereby preventing short circuits caused by contact between the first and second electrode sheets and improving safety.

[0026] In some embodiments of the present application, the head portion of the second segment is connected to the separator.

[0027] In the above technical solution, by connecting the head of the second segment to the separator, the separator can position the head of the second segment relative to the separator, preventing displacement of the first and second segments. When winding, the separator drives the head of the second segment to wind it, providing the driving force required for winding to the second segment, so that the first and second segments can be wound in sequence.

[0028] In some embodiments of the present application, the second electrode sheet comprises a third segment and a fourth segment, a third active material layer is disposed in the third segment, a fourth active material layer is disposed in the fourth segment, and the third segment is located upstream of the fourth segment in the winding direction from the inside to the outside.

[0029] In the above technical solution, by dividing the second electrode sheet into a third segment and a fourth segment, the third segment located in the inner layer and the fourth segment located in the outer layer can be treated differently, and the third segment and the fourth segment can have different physical or chemical properties. The differentiation between the inner and outer layers allows for better adjustment of the performance of the electrode unit.

[0030] In some embodiments of the present application, the coating density of the third active material layer is different from the coating density of the fourth active material layer, and / or the thickness of the third active material layer is different from the thickness of the fourth active material layer, and / or the active material of the third active material layer is the same as or different from the active material of the fourth active material layer.

[0031] In the above technical solution, by adjusting the coating density, thickness and active material recipe of the third and fourth active material layers and changing the physical or chemical performance of the third and fourth segments, the electrode unit can meet different performance requirements and satisfy different usage environments.

[0032] In some embodiments of the present application, the ratio of the thickness of the third active material layer to the thickness of the fourth active material layer is 1 / 2-3 / 2.

[0033] In the above technical solution, if the coating density of the third active material layer is smaller than the coating density of the fourth active material layer and the ratio of the thickness of the third active material layer to the thickness of the fourth active material layer satisfies the above range, it can ensure that the third segment and the fourth segment are smoothly connected, prevent the active material from falling off or being scratched, and maintain the quality of the electrode unit.

[0034] In some embodiments of the present application, in the winding direction from the inside to the outside, the tail portion of the third segment and the head portion of the fourth segment are connected, or a gap is provided between the tail portion of the third segment and the head portion of the fourth segment.

[0035] In the above technical solution, when the tail portion of the third segment and the head portion of the fourth segment are connected, the continuity of the second electrode sheet can be ensured, and since the second electrode sheet contains more active material, the electrode unit can have a higher energy density. If a gap is provided between the tail portion of the third segment and the head portion of the fourth segment, the third and fourth segments can be easily processed, thereby reducing the difficulty of manufacturing the second electrode sheet.

[0036] In some embodiments of the present application, the second electrode sheet further comprises a second current collector, and the third active material layer and the fourth active material layer are respectively disposed on the second current collector.

[0037] In some embodiments of the present application, the second electrode sheet further comprises a third current collector segment and a fourth current collector segment, the third active material layer being disposed on the third current collector segment to form the third segment, and the fourth active material layer being disposed on the fourth current collector segment to form the fourth segment.

[0038] In the above technical solution, the third active material layer is disposed on the third current collector segment to form the third segment, and the fourth active material layer is disposed on the fourth current collector segment to form the fourth segment, which makes it easy to manufacture the third segment and the fourth segment.

[0039] In some embodiments of the present application, the tail portion of the third segment and the head portion of the fourth segment are connected by a second connecting portion.

[0040] In the above technical solution, by connecting the third segment and the fourth segment at the second connection part, the third segment and the fourth segment can be positioned relative to each other, preventing displacement of the third segment and the fourth segment. When the third segment is wound, the third segment drives the fourth segment via the second connection part, providing the fourth segment with the driving force necessary for winding, thereby realizing the sequential winding of the third segment and the fourth segment.

[0041] In some embodiments of the present application, the electrode unit further includes a separator separating the first electrode sheet and the second electrode sheet, and the head portion of the fourth segment is connected to the separator.

[0042] In the above technical solution, by connecting the head of the fourth segment to the separator, the separator can position the head of the fourth segment relative to the separator, preventing displacement of the third and fourth segments. When winding, the separator drives the head of the fourth segment to wind it, providing the fourth segment with the driving force necessary for winding, so that the third and fourth segments can be wound in order.

[0043] In some embodiments of the present application, the electrode unit comprises two separators located on either side of the second electrode sheet, and the head portion of the second segment is connected to one of the separators, and the head portion of the fourth segment is connected to the other of the separators.

[0044] In the above technical solution, by connecting one separator to the head portion of the second segment and the other separator to the head portion of the fourth segment, one separator can restrict the position of the second segment, and the other separator can restrict the position of the fourth segment. When forming an electrode unit by winding, one separator drives the head portion of the second segment to wind it and provides the driving force necessary for winding to the second segment, thereby realizing the sequential winding of the first segment and the second segment. In addition, the other separator drives the head portion of the fourth segment to wind it and provides the driving force necessary for winding to the fourth segment, thereby realizing the sequential winding of the third segment and the fourth segment.

[0045] In some embodiments of the present application, the number of turns in the third segment is less than the number of turns in the fourth segment.

[0046] In the above technical solution, the number of turns of the third segment is set to be less than the number of turns of the fourth segment, i.e., the number of turns of the fourth active material layer is set to be greater than the number of turns of the third active material layer. When the coating density of the fourth active material layer is greater than that of the third active material layer and the thickness of the electrode unit is the same, the greater the number of turns of the fourth active material layer, the higher the energy density of the electrode unit can be ensured.

[0047] In some embodiments of the present application, the number of turns in the first segment is less than the number of turns in the second segment.

[0048] In the above technical solution, the number of turns of the first segment is smaller than the number of turns of the second segment, which can ensure that the electrode unit has a higher energy density.

[0049] In some embodiments of the present application, the coating density of the second active material layer is 10%-200% greater than the coating density of the first active material layer.

[0050] In the above technical solution, by making the coating density of the second active material layer greater than that of the first active material layer, it is possible to ensure that the first electrode sheet has more active material, and therefore it is possible to ensure that the battery formed by the electrode unit has a greater energy density.

[0051] In a second aspect, the present application provides a battery cell including the electrode unit of the above embodiment.

[0052] In a third aspect, the present application provides a battery including the battery cell in the above embodiment.

[0053] In a fourth aspect, the present application provides an electrical device including the battery of the above embodiment.

[0054] In a fifth aspect, the present application provides a winding device, the winding device including a first segment and a second segment, a first providing device for providing a first electrode sheet, the first segment having a first active material layer disposed thereon and a second active material layer disposed thereon, a second providing device for providing a second electrode sheet having a polarity opposite to that of the first electrode sheet, a separator providing mechanism for providing a separator, and a winding mechanism disposed downstream of the first providing device, the second providing device, and the separator providing mechanism, the winding mechanism winding the first segment, the second segment, the separator, and the second electrode sheet in a winding direction to form an electrode unit, the first providing device configured to provide the first electrode sheet so that the first segment enters the winding mechanism first and the second segment enters the winding mechanism after the first segment.

[0055] In the winding device of the present application, the first segment, the second segment, the separator, and the second electrode sheet are wound by the winding mechanism to form an electrode unit, so that the first segment and the second segment can be treated differently, and the first segment and the second segment can have different physical or chemical properties. Differentiation between the inside and outside allows for better adjustment of the performance of the electrode unit.

[0056] In some embodiments of the present application, the coating density of the first active material layer is different from the coating density of the second active material layer, and / or the thickness of the first active material layer is different from the thickness of the second active material layer, and / or the active material of the first active material layer is the same as or different from the active material of the second active material layer.

[0057] In the above technical solution, by adjusting the coating density, thickness and active material composition of the first and second active material layers and changing the physical or chemical properties of the first and second segments, the electrode unit can meet different performance requirements and satisfy different usage environments.

[0058] In some embodiments of the present application, the second electrode sheet comprises a third segment and a fourth segment, a third active material layer is disposed on the third segment, and a fourth active material layer is disposed on the fourth segment, and the second providing device is configured to provide the second electrode sheet so that the third segment enters the winding mechanism first and the fourth segment enters the winding mechanism after the third segment.

[0059] In the above technical solution, the third and fourth segments can be treated differently, so that they have different physical or chemical properties. The differentiation between the inside and outside allows for better adjustment of the performance of the electrode unit.

[0060] In some embodiments of the present application, the coating density of the third active material layer is different from the coating density of the fourth active material layer, and / or the thickness of the third active material layer is different from the thickness of the fourth active material layer, and / or the active material of the third active material layer is the same as or different from the active material of the fourth active material layer.

[0061] In the above technical solution, by adjusting the coating density, thickness and active material recipe of the third and fourth active material layers and changing the physical or chemical properties of the third and fourth segments, the electrode unit can meet different performance requirements and satisfy different usage environments.

[0062] In some embodiments of the present application, the separator includes a first separator and a second separator, the separator providing mechanism provides the first separator and the second separator, the winding device further includes a first combining mechanism located downstream of the first providing device and the separator providing mechanism and combining the first separator, the first electrode sheet, and the second separator to form a first electrode sheet unit, the first providing device is configured to provide the first electrode sheet such that the first segment enters the first combining mechanism first and the second segment enters the first combining mechanism after the first segment, and the winding mechanism is located downstream of the first combining mechanism and winds up the first electrode sheet unit and the second electrode sheet in a winding direction to form an electrode unit.

[0063] In the above technical solution, the first separator, the first electrode sheet, and the second separator are combined to form a first electrode sheet unit. In this case, the first separator and the second separator serve to position the first electrode sheet, sandwich the second segment, drive the second segment for winding, and provide the driving force required for winding to the second segment, thereby realizing the sequential winding of the first segment and the second segment.

[0064] In some embodiments of the present application, the first providing device includes a first connecting mechanism that connects the tail portion of the first segment and the head portion of the second segment at a first connecting portion.

[0065] In the above technical proposal, by connecting the first segment and the second segment at the first connection part, when the first segment is wound up, the first segment drives the second segment via the first connection part, and provides the second segment with the driving force necessary for winding, thereby realizing the winding of the first segment and the second segment in sequence.

[0066] In some embodiments of the present application, the separator includes a first separator and a second separator, the winding device includes two separator providing mechanisms, one of which provides the first separator and the other of which provides the second separator, and the winding device further includes a first combining mechanism located downstream of the first providing device and one of the separator providing mechanisms and configured to combine the first polar sheet and the first separator to form a first polar sheet unit, and a second combining mechanism located downstream of the second providing device and the other of the separator providing mechanisms. and a second combining mechanism located on the downstream side and combining the second electrode sheet and the second separator to form a second electrode sheet unit, wherein the first providing device is configured to provide the first electrode sheet so that the first segment enters the first combining mechanism first and the second segment enters the first combining mechanism after the first segment, and the winding mechanism is installed downstream of the first combining mechanism and the second combining mechanism and winds up the first electrode sheet unit and the second electrode sheet unit in a winding direction to form an electrode unit.

[0067] In the above technical solution, the first combining mechanism combines the first electrode sheet and the first separator to form a first electrode sheet unit, thereby enabling the first separator to position the first electrode sheet. The second combining mechanism combines the second electrode sheet and the second separator to form a second electrode sheet unit, thereby enabling the second separator to position the second electrode sheet. This ensures that the first and second electrode sheets in the electrode unit formed by winding are isolated by the first and second separators, prevents short circuits due to contact between the first and second electrode sheets, and ensures the safety of battery cells formed by the electrode units.

[0068] In a sixth aspect, the present application provides a winding method, the winding method including the steps of: providing a first electrode sheet including a first segment and a second segment, the first segment having a first active material layer disposed thereon and the second segment having a second active material layer disposed thereon, providing a second electrode sheet having a polarity opposite to that of the first electrode sheet, providing a separator, and winding the first segment, the second segment, the separator, and the second electrode sheet in a winding direction such that the first segment, the separator, and the second electrode sheet are wound first, and the second segment, the separator, and the second electrode sheet are wound after the first segment, to form an electrode unit.

[0069] In some embodiments of the present application, the coating density of the first active material layer is different from the coating density of the second active material layer, and / or the thickness of the first active material layer is different from the thickness of the second active material layer, and / or the active material of the first active material layer is the same as or different from the active material of the second active material layer.

[0070] The above description is merely a summary of the technical solution of the present application. The technical solution of the present application can be more clearly understood by practicing the content of the specification. In order to make the above and other objectives, features and advantages of the present application more clearly understood, the following specific embodiments of the present application are specifically presented. [Brief explanation of the drawings]

[0071] In order to clarify the technical solutions of the embodiments of the present application, the drawings necessary for describing the embodiments of the present application are briefly described below, and it is obvious that the drawings described only show some embodiments of the present application, and those skilled in the art can obtain other related drawings based on these drawings without using inventive ability. [Figure 1] 1 is a schematic diagram illustrating the configuration of a vehicle according to some embodiments of the present application. [Figure 2] 1 is an exploded schematic diagram of a battery configuration according to some embodiments of the present application. FIG. [Figure 3]1 is an exploded schematic diagram of a battery cell configuration according to some embodiments of the present application. FIG. [Figure 4] 1 is a schematic diagram illustrating the configuration of an electrode unit according to some embodiments of the present application. [Figure 5] 1 is a schematic diagram illustrating the configuration of a first electrode sheet according to some embodiments of the present application. [Figure 6] 4A to 4C are schematic diagrams illustrating the configuration of a first electrode sheet according to some other embodiments of the present application. [Figure 7] 3 is a schematic diagram illustrating a case where a first segment and a second segment are connected via a first connecting portion according to some embodiments of the present application. FIG. [Figure 8] FIG. 2 is a schematic diagram illustrating connections between first and second segments and separators according to some embodiments of the present application. [Figure 9] 5A to 5C are schematic diagrams illustrating connections between first and second segments and separators according to some other embodiments of the present application. [Figure 10] 10A to 10C are schematic diagrams illustrating the configuration of electrode units according to some other embodiments of the present application. [Figure 11] 1 is a schematic diagram illustrating the configuration of a second electrode sheet according to some embodiments of the present application. [Figure 12] 10A to 10C are schematic diagrams illustrating the configuration of a second electrode sheet according to some other embodiments of the present application. [Figure 13] 10 is a schematic diagram illustrating a case where a third segment and a fourth segment are connected via a second connection portion according to some embodiments of the present application. FIG. [Figure 14] FIG. 2 is a schematic diagram showing connections between a first electrode sheet and a second electrode sheet and a separator according to some embodiments of the present application. [Figure 15] 1 is a schematic diagram illustrating the configuration of a winding device according to some embodiments of the present application. [Figure 16] FIG. 2 is a schematic diagram illustrating a first transport mechanism according to some embodiments of the present application when the first transport mechanism is located at a first transport position. [Figure 17] FIG. 2 is a schematic diagram illustrating a second transport mechanism according to some embodiments of the present application when the second transport mechanism is located at a first transport position. [Figure 18]10A to 10C are schematic diagrams illustrating the configuration of a winding device according to some other embodiments of the present application. [Figure 19] FIG. 10 is a schematic diagram illustrating a third transport mechanism according to some embodiments of the present application when the third transport mechanism is located at a second transport position. [Figure 20] FIG. 10 is a schematic diagram illustrating a fourth transport mechanism according to some embodiments of the present application when the fourth transport mechanism is located at a second transport position. [Figure 21] 1 is a schematic flow diagram of a winding method according to some embodiments of the present application.

[0072] The drawings are not drawn to scale. DETAILED DESCRIPTION OF THE INVENTION

[0073] In order to clarify the objectives, technical solutions and advantages of the embodiments of the present application, the technical solutions of the embodiments of the present application will be clearly explained below with reference to the drawings of the embodiments of the present application. The described embodiments are only some of the embodiments of the present application, and of course, do not represent all of the embodiments. All other embodiments that can be obtained by those skilled in the art based on the embodiments of the present application without using inventive ability also fall within the scope of protection of the present application.

[0074] Unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. In this application, the terms used in the specification are merely for the purpose of specifically describing the examples and are not intended to limit the application. Furthermore, the terms "comprise," "have," and similar terms used in the specification, claims, and drawings of this application are intended to cover a non-exclusive inclusion. Terms such as "first," "second," and the like used in the specification, claims, and drawings of this application are merely used to distinguish between similar objects and are not intended to limit a specific order or sequence.

[0075] References to an "embodiment" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. Appearances of this term in various parts of the specification do not all refer to the same embodiment, nor are they separate or alternative embodiments exclusive of one another. It is explicitly or implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0076] In the description of this application, unless otherwise clearly defined or limited, terms such as "attached," "coupled," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to a fixed connection, a detachable connection, or an integral connection. They may also refer to a direct connection, an indirect connection via an intermediate object, or communication between the interiors of two elements. Those skilled in the art will be able to understand the specific meanings of the above terms in this application depending on the specific circumstances.

[0077] The term "and / or" used in this application is merely for explaining the relation between related objects and indicates the existence of three relationships. For example, A and / or B can indicate three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this specification generally indicates that the related objects before and after it are in an "or" relationship.

[0078] In this application, "plurality" means two or more (including two); similarly, "groups" means two or more (including two groups); and "plurality" means two or more (including two).

[0079] In this application, a battery is a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, a battery referred to in this application may include a battery module, a battery pack, or the like.

[0080] A battery cell includes an electrode unit and an electrolyte. The electrode unit consists of a positive electrode sheet, a negative electrode sheet, and a separator. The battery cell operates primarily through the transfer of metal ions between the positive and negative electrode sheets. The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer is coated on the surface of the positive electrode current collector. The positive electrode current collector without the positive electrode active material layer protrudes from the positive electrode current collector coated with the positive electrode active material layer and is used as a positive electrode tab. For example, in a lithium-ion battery, the positive electrode current collector is made of aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode current collector. The negative electrode current collector without the negative electrode active material layer protrudes from the negative electrode current collector coated with the negative electrode active material layer and is used as a negative electrode tab. The negative electrode current collector is made of copper, and the negative electrode active material can be carbon, silicon, etc. To ensure that it does not melt even when a large current passes through it, multiple positive electrode tabs are provided and stacked, and multiple negative electrode tabs are provided and stacked. The separator can be made of PP (polypropylene), PE (polyethylene), etc.

[0081] The separator has electrical insulation properties and separates adjacent positive and negative electrode sheets to prevent short circuits between them. The separator has a large number of microscopic through-holes, allowing the passage of electrolyte ions. The separator is highly permeable to lithium ions, so it is essentially unable to block their passage.

[0082] To reduce the volume of a lithium-ion battery cell and increase its energy density, the negative electrode sheet, positive electrode sheet, and separator in the electrode unit of the lithium-ion battery cell are wound and compacted. The electrode unit has a flat portion and curved portions located at both ends of the flat portion. The flat portion refers to the flat portion of the electrode unit, i.e., the surfaces of the negative electrode sheet, positive electrode sheet, and separator in the flat portion are all flat. The curved portion refers to the curved portion of the electrode unit, i.e., the surfaces of the negative electrode sheet, positive electrode sheet, and separator in the curved portion are all curved. In the examples of this application, a wound electrode unit will be described as an example. In the examples of this application, there are two separators. The electrode unit may be formed by stacking and winding a negative electrode sheet, a first separator, a positive electrode sheet, and a second separator in this order, or may be formed by stacking and winding a first separator, a negative electrode sheet, a second separator, and a positive electrode sheet in this order.

[0083] An active material is applied to the surface of a current collector to form an active material layer. The application density of the active material layer refers to the application weight of active material per unit area. After the active material layer is applied to the current collector, it is dried, rolled, etc., to obtain an electrode sheet. Drying is performed to evaporate the moisture in the active material layer until it meets the process requirements. Roller rolling is performed to consolidate the active material layer and reduce the thickness of the electrode sheet until it meets the process requirements. After the electrode sheet is dried, rolled, etc., the greater the application density of the active material in the electrode sheet, the lower the fracture toughness of the electrode sheet. In this case, bending the electrode sheet may cause cracking or tearing.

[0084] As battery technology develops, many design factors must be considered, including performance parameters such as energy density, cycle life, discharge capacity, charge / discharge efficiency, etc. In addition, battery safety must also be considered.

[0085] The performance of a battery cell is determined by the performance of the electrode unit. The electrode unit is generally formed by winding a positive electrode sheet and a negative electrode sheet, so its performance is determined by the performance of the electrode sheet. The electrode sheet is generally in the form of a continuous tape, and the performance at each position on the electrode sheet is approximately the same, so the performance of the electrode unit formed by winding the electrode sheet is determined. However, the performance of the electrode unit is relatively poor, making it impossible to differentiate.

[0086] For example, in conventional electrode sheets, the coating density of the active material layer is increased to increase energy density. This reduces the fracture toughness of the electrode sheet after roller rolling, making the electrode sheet brittle. In this case, bending under force can lead to cracking and even tearing. During the consolidation of the electrode unit after winding or subsequent manufacturing processes, cracking and even tearing can easily occur at the curved portions of the electrode sheet. This can lead to insufficient lithium insertion space at the curved portions, leading to lithium precipitation and the risk of lithium crystals penetrating the separator. Furthermore, a torn electrode sheet can also penetrate the separator, potentially causing a short circuit within the battery, affecting the safety of the battery cell. Therefore, battery cells made of electrode units cannot be used in applications with high safety requirements.

[0087] In consideration of the above problems, the inventors have designed an electrode unit that solves the problem of poor electrode unit performance and a lack of differentiated processing. The electrode unit includes a first electrode sheet and a second electrode sheet with opposite polarities, stacked and wound together. The first electrode sheet includes a first segment and a second segment, with a first active material layer disposed on the first segment and a second active material layer disposed on the second segment. In the winding direction from the inside to the outside, the first segment is located upstream of the second segment. The first segment, located on the inner layer, and the second segment, located on the outer layer, are treated differently, resulting in different physical or chemical properties for the first and second segments. Differentiating the inner and outer layers allows the performance of the electrode unit to be better tailored to meet different usage requirements.

[0088] In such an electrode unit, the first electrode sheet is divided into a first segment and a second segment, and different treatments can be applied to the first segment and the second segment according to different performance requirements.

[0089] The battery cells of the embodiments of the present application can be applied to, but are not limited to, electrical equipment such as vehicles, ships, and aircraft. Furthermore, the battery cells and batteries of the present application may be used to configure a power supply system for electrical equipment.

[0090] An embodiment of the present application provides an electrical device that uses a battery as a power source. Examples of the electrical device include, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric bicycles, electric motorcycles, electric cars, ships, and aircraft. Electric toys include both stationary and mobile devices, such as game consoles, electric car toys, electric ship toys, and electric plane toys. Aircraft include airplanes, rockets, space shuttles, and spacecraft.

[0091] In the following embodiment, for convenience of explanation, the vehicle 1000 will be used as an example to describe the electrical equipment of one embodiment of the present application.

[0092] FIG. 1 shows a schematic diagram of a vehicle 1000 according to some embodiments of the present application. As shown in FIG. 1, the vehicle 1000 may be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle, and new energy vehicles may include electric vehicles, hybrid vehicles, and range-extended electric vehicles. A battery 100 is disposed inside the vehicle 1000, and the battery 100 may be installed at the bottom, front, or rear of the vehicle 1000. The battery 100 is used to power the vehicle 1000. For example, the battery 100 may be used in the vehicle's electrical circuit system as a power source for the vehicle's 1000, such as for starting, navigating, and running.

[0093] The vehicle 1000 further includes a controller 200 and a motor 300, and the controller 200 controls the power supply from the battery 100 to the motor 300. For example, the battery 100 can be used as a power source for starting, navigating, and running the vehicle 1000.

[0094] In some embodiments of the present application, the battery 100 can be used not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000 to provide driving power to the vehicle 1000 instead of gasoline or natural gas.

[0095] FIG. 2 is an exploded schematic diagram of a battery 100 according to some embodiments of the present application. As shown in FIG. 2, the battery 100 includes a housing 10, battery cells 20, and the battery cells 20 housed within the housing 10. The housing 10 provides a housing space for the battery cells 20 and may have various configurations. In some embodiments, the housing 10 includes a first sub-housing 11 and a second sub-housing 12, which are combined to form a housing space for the battery cells 20. The second sub-housing 12 has a hollow structure with one end open, and the first sub-housing 11 has a plate-like structure. The first sub-housing 11 is attached to the open side of the second sub-housing 12, thereby forming a housing space together with the first sub-housing 11 and the second sub-housing 12. Both the first sub-housing 11 and the second sub-housing 12 may have a hollow structure with one end open. The opening side of the first sub-housing 11 and the opening side of the second sub-housing 12 are joined together. Of course, the housing 10 formed by the first sub-housing 11 and the second sub-housing 12 may be formed into various shapes, such as a cylindrical body or a rectangular parallelepiped.

[0096] The battery 100 may include multiple battery cells 20. The multiple battery cells 20 may be connected in series, parallel, or series-parallel. Series-parallel refers to connecting multiple battery cells 20 in series and parallel. The multiple battery cells 20 may be connected directly, in series, in parallel, or in series-parallel, and the entire configuration of the multiple battery cells 20 may be housed within the housing 10. Of course, it is also possible to first connect multiple battery cells 20 in series, in parallel, or in series-parallel to assemble the battery 100 in the form of a battery module, and then further connect multiple battery modules in series, in parallel, or in series-parallel and house them as a whole within the housing 10. The battery 100 may also include other components, such as bus bars, for achieving electrical connection between the multiple battery cells 20.

[0097] Each battery cell 20 may be a secondary battery or a primary battery, and may be, but is not limited to, a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery. The battery cells 20 may be cylindrical, flat, rectangular, or have other shapes.

[0098] 3 is an exploded schematic view of a battery cell 20 according to some embodiments of the present application. As shown in FIG. 3, the battery cell 20 refers to the smallest unit that constitutes a battery. As shown in FIG. 3, the battery cell 20 includes an end cover 21, a case 22, an electrode unit 23, and other functional components.

[0099] The end cover 21 is a component that serves as a lid at the opening of the case 22 and isolates the internal environment of the battery cell 20 from the external environment. The shape of the end cover 21 is not limited, as long as it conforms to the shape of the case 22. Optionally, the end cover 21 may be made of a material with a certain hardness and strength (e.g., aluminum alloy). This makes the end cover 21 less likely to deform when subjected to an extrusion impact, thereby providing the battery cell 20 with higher structural strength and improved safety. The end cover 21 may be provided with functional components such as electrode terminals 24. The electrode terminals 24 may be used to electrically connect to the electrode units 23 to output or input electrical energy to or from the battery cell 20. In some embodiments, the end cover 21 may further be provided with a pressure release mechanism that releases internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The end cover 21 may be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application are not limited thereto. In some embodiments, an insulating member may be installed inside the end cover 21. The insulating member isolates the electrical connections in the case 22 from the end cover 21 to reduce the risk of short circuits. Illustratively, the insulating member may be made of plastic, rubber, or the like.

[0100] The case 22 may be an assembly that, together with the end cover 21, forms an internal environment for the battery cell 20. The formed internal environment may be used to accommodate the electrode unit 23, electrolyte, and other components. The case 22 and the end cover 21 may be separate components, or an opening may be formed in the case 22, and the end cover 21 may be installed as a lid to cover the opening, thereby forming the internal environment for the battery cell 20. Without limitation, the end cover 21 and the case 22 may be integrated. Specifically, the end cover 21 and the case 22 may first form a common connection surface before other components are inserted into the case. If it is necessary to package the interior of the case 22, the end cover 21 may close the case 22. The shape and dimensions of the case 22 are not limited and may be, for example, a rectangular parallelepiped, cylindrical, hexagonal prism, etc. Specifically, the shape of the case 22 may be determined based on the specific shape and dimensions of the electrode unit 23. The material of the case 22 may be, for example, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application is not particularly limited thereto.

[0101] The electrode unit 23 is a component in which an electrochemical reaction occurs in the battery cell 20. The case 22 may include one or more electrode units 23. The electrode unit 23 is primarily formed by winding a positive electrode sheet and a negative electrode sheet, and a separator is typically provided between the positive electrode sheet and the negative electrode sheet. The separator serves to insulate and isolate the positive electrode sheet and the negative electrode sheet to prevent internal short circuits. The portions of the positive electrode sheet and the negative electrode sheet that contain active material form the main body of the battery core unit, while the portions of the positive electrode sheet and the negative electrode sheet that do not contain active material form tabs, respectively. The positive electrode tab and the negative electrode tab may both be located at one end of the main body, or may be located at both ends of the main body. During the charge and discharge process of the battery, the positive electrode active material and the negative electrode active material react with the electrolyte, forming a current circuit through the connection between the tabs and the electrode terminals.

[0102] Some embodiments of the present application will be described with reference to FIGS. 4 to 6. FIG. 4 is a schematic diagram of an electrode unit 23 according to some embodiments of the present application. FIG. 5 is a schematic diagram of a first electrode sheet 231 according to some embodiments of the present application. FIG. 6 is a schematic diagram of a first electrode sheet 231 according to other some embodiments of the present application. The present application provides an electrode unit 23, which includes a first electrode sheet 231 and a second electrode sheet 232 having opposite polarities. The first electrode sheet 231 and the second electrode sheet 232 are stacked and wound to form the electrode unit 23. The first electrode sheet 231 includes a first segment 2311 and a second segment 2312. A first active material layer 2311a is disposed in the first segment 2311, and a second active material layer 2312a is disposed in the second segment 2312. In the winding direction from the inside to the outside, the first segment 2311 is located upstream of the second segment 2312.

[0103] The first electrode sheet 231 and the second electrode sheet 232 have opposite polarities, and the first electrode sheet 231 may be a negative electrode sheet and the second electrode sheet 232 may be a positive electrode sheet, or the first electrode sheet 231 may be a positive electrode sheet and the second electrode sheet 232 may be a negative electrode sheet. In the embodiments of the present application, an example will be described in which the first electrode sheet 231 is a negative electrode sheet and the second electrode sheet 232 is a positive electrode sheet.

[0104] The first segment 2311 and the second segment 2312 are two parts that make up the first pole sheet 231 and are arranged in the winding direction from the inside to the outside. The first segment 2311 and the second segment 2312 may be formed by integral molding or may be arranged separately. In the winding direction, the first segment 2311 and the second segment 2312 may partially overlap each other, or the tail portion of the first segment 2311 and the head portion of the second segment 2312 may be joined as shown in FIG. 5, or a gap may be provided between the first segment 2311 and the second segment 2312 as shown in FIGS. 4 and 6. Alternatively, the tail portion of the first segment 2311 and the head portion of the second segment 2312 may be joined, or a small gap may be provided between the first segment 2311 and the second segment 2312. In these cases, since the first segment 2311 and the second segment 2312 do not overlap, an increase in the thickness of the electrode unit 23 due to the overlapping portion between the first segment 2311 and the second segment 2312 can be prevented, and the space occupied can be reduced.

[0105] The fact that the first segment 2311 is located upstream of the second segment 2312 means that when the electrode unit 23 is formed by winding, the first segment 2311 is wound before the second segment 2312, and the first segment 2311 is closer to the winding center than the second segment 2312.

[0106] The first segment 2311 is a portion of the first electrode sheet 231 located inside the electrode unit 23, i.e., a portion close to the winding center of the first electrode sheet 231. The second segment 2312 is a portion of the first electrode sheet 231 located outside the electrode unit 23, i.e., a portion away from the winding center of the first electrode sheet 231. The first segment 2311 has a wound structure and the number of turns is one or more, i.e., the first segment 2311 has at least two curved portions 235. The second segment 2312 has a wound structure and the number of turns is greater than one, i.e., the second segment 2312 has multiple curved portions 235.

[0107] In the electrode unit 23 of the embodiment of the present application, the first electrode sheet 231 includes a first segment 2311 and a second segment 2312, and in the winding direction from the inside to the outside, the first segment 2311 is located upstream of the second segment 2312. By dividing the first electrode sheet 231 into the first segment 2311 and the second segment 2312, different treatments can be applied to the first segment 2311 located on the inner layer and the second segment 2312 located on the outer layer, and the first segment 2311 and the second segment 2312 can have different physical or chemical properties. Differentiation between the inner and outer segments allows the performance of the electrode unit to be better tailored to meet different usage requirements.

[0108] In some embodiments of the present application, the coating density of first active material layer 2311a is different from the coating density of second active material layer 2312a.

[0109] The coating density of the first active material layer 2311a refers to the coating weight of the active material of the first active material layer 2311a per unit area. The coating density of the second active material layer 2312a refers to the coating weight of the active material of the second active material layer 2312a per unit area.

[0110] By making the coating density of the first active material layer 2311a and the coating density of the second active material layer 2312a different, the energy density of the electrode unit 23 can be adjusted, and different energy density requirements for the electrode unit can be met.

[0111] In some embodiments of the present application, the coating density of first active material layer 2311a is less than the coating density of second active material layer 2312a.

[0112] The electrode unit 23 has a flat portion 234 and curved portions 235 located on both ends of the flat portion 234. The flat portion 234 refers to a flat portion of the electrode unit 23, i.e., the surfaces of the first electrode sheet 231, the second electrode sheet 232, and the separator at the flat portion 234 are all flat. The curved portion 235 refers to a curved portion of the electrode unit 23, i.e., the first electrode sheet 231, the second electrode sheet 232, and the separator at the curved portion 235 are all curved. In other words, the surfaces of the first electrode sheet 231, the second electrode sheet 232, and the separator of each layer at the portion corresponding to the curved portion 235 of the electrode unit 23 are all curved.

[0113] By making the application density of the first active material layer 2311a smaller than that of the second active material layer 2312a, the fracture toughness of the first segment 2311 becomes greater than that of the second segment 2312, and cracks or breaks do not easily occur in the curved portion 235 of the first segment 2311. This reduces the incidence of cracks or breaks in the first electrode sheet 231 and improves the safety of the battery cell 20 formed by the electrode unit 23.

[0114] In some embodiments of the present application, the coating density of second active material layer 2312a is 10% to 200% greater than the coating density of first active material layer 2311a.

[0115] When the application density of the second active material layer 2312a is H2 and the application density of the first active material layer 2311a is H1, the relationship 0.1≦(H2−H1) / H1≦2 is satisfied.

[0116] By making the coating density of the second active material layer 2312a greater than that of the first active material layer 2311a, it is possible to ensure that the first electrode sheet 231 contains more active material, and to ensure that the battery cell 20 formed by the electrode unit 23 has a greater energy density.

[0117] Optionally, the coating density of second active material layer 2312a is 20%-150% greater than the coating density of first active material layer 2311a.

[0118] Optionally, the coating density of second active material layer 2312a is 40%-120% greater than the coating density of first active material layer 2311a.

[0119] Optionally, the coating density of second active material layer 2312a is greater than the coating density of first active material layer 2311a, such as 30%, 50%, 60%, 70%, 100%, 130%, 150% or 180%.

[0120] In some embodiments of the present application, the ratio of the thickness of the first active material layer 2311a to the thickness of the second active material layer 2312a is 1 / 2 to 3 / 2.

[0121] When the thickness of the first active material layer 2311a is D1 and the thickness of the second active material layer 2312a is D2, the relationship 1 / 2≦D1 / D2≦3 / 2 is satisfied. In other words, the thickness of the first active material layer 2311a and the thickness of the second active material layer 2312a are approximately the same.

[0122] For example, D1 / D2 may be 5 / 8, 3 / 4, 7 / 8, 1, 9 / 8, 5 / 4, 1 1 / 8, etc.

[0123] When the application density of the first active material layer 2311a is smaller than that of the second active material layer 2312a and the ratio of the thickness of the first active material layer 2311a to the thickness of the second active material layer 2312a satisfies the above range, it is possible to ensure that the connection between the first segment 2311 and the second segment 2312 is smooth, it is possible to prevent the active material from falling off or being scratched, and it is possible to maintain the quality of the electrode unit 23.

[0124] In some embodiments of the present application, the active material material of first active material layer 2311a and the active material material of second active material layer 2312a may be the same or different.

[0125] By making the active material of the first active material layer 2311a different from the active material of the second active material layer 2312a, the performance of the first segment 2311 and the second segment 2312 can be adjusted so that the electrode unit 23 has different physical or chemical performance.

[0126] For example, the recipes for the first active material layer 2311a and the second active material layer 2312a may be the same, e.g., using the same types of active material materials and the same active material material composition. Alternatively, the recipes for the first active material layer 2311a and the second active material layer 2312a may be different, e.g., using different types of active material materials and the active material material composition may also be different. Alternatively, the active material materials for the first active material layer 2311a and the second active material layer 2312a may be of different chemical systems.

[0127] For example, if the active material of the first active material layer 2311a and the active material of the second active material layer 2312a are negative electrode active material, the negative electrode active material may be at least one of graphite (artificial graphite, natural graphite), amorphous carbon (soft carbon, hard carbon, other amorphous carbon), and lithium titanate. For example, if the active material of the first active material layer 2311a and the active material of the second active material layer 2312a are positive electrode active material, the positive electrode active material may be at least one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, nickel cobalt manganese oxide, lithium excess lithium manganese oxide, and nickel cobalt aluminum oxide.

[0128] In some embodiments of the present application, in the inside-to-outside winding direction, the tail portion of the first segment 2311 and the head portion of the second segment 2312 are connected, or there is a gap between the tail portion of the first segment 2311 and the head portion of the second segment 2312, as shown in Figures 4 and 6.

[0129] The tail portion of the first segment 2311 refers to the end of the first segment 2311 in the winding direction, i.e., the tail portion of the first segment 2311 refers to the last part of the first segment 2311. The head portion of the second segment 2312 refers to the neck portion of the second segment 2312 in the winding direction, i.e., the head portion of the second segment 2312 refers to the beginning part of the second segment 2312.

[0130] When the tail portion of the first segment 2311 and the head portion of the second segment 2312 are connected, the continuity of the first electrode sheet 231 can be ensured, and since the first electrode sheet 231 contains more active material, it is possible to ensure a higher energy density of the electrode unit 23. When a gap is provided between the tail portion of the first segment 2311 and the head portion of the second segment 2312, it becomes easier to process the first segment 2311 and the second segment 2312, thereby reducing the difficulty of manufacturing the first electrode sheet 231.

[0131] In some embodiments of the present application, as shown in FIG. 5, the first electrode sheet 231 further includes a first current collector 2313, and the first active material layer 2311a and the second active material layer 2312a are each disposed on the first current collector 2313.

[0132] The first current collector 2313 is in the form of a continuous tape, and the first active material layer 2311a and the second active material layer 2312a are each disposed on the first current collector 2313. In this case, the first segment 2311 is a portion of the first electrode sheet 231 where the active material layer is applied more densely, and the second segment 2312 is a portion of the first electrode sheet 231 where the active material layer is applied more densely. When manufacturing such a first electrode sheet 231, when rolling the active material layer with rollers, the distance between the pair of rollers is adjusted to change the force with which the pair of rollers roll the first electrode sheet 231, thereby forming the first segment 2311, which is a portion where the active material layer is applied more densely, and the second segment 2312, which is a portion where the active material layer is applied more densely.

[0133] In some embodiments of the present application, as shown in FIG. 6 , the first electrode sheet 231 further includes a first current collector segment 2311b and a second current collector segment 2312b, in which a first active material layer 2311a is disposed on the first current collector segment 2311b to form the first segment 2311, and a second active material layer 2312a is disposed on the second current collector segment 2312b to form the second segment 2312.

[0134] The first current collector segment 2311b and the second current collector segment 2312b are two different current collector segments, and in this case the first segment 2311 and the second segment 2312 are two separate parts.

[0135] By disposing the first active material layer 2311a on the first current collector segment 2311b to form the first segment 2311, and disposing the second active material layer 2312a on the second current collector segment 2312b to form the second segment 2312, the processing and manufacturing of the first segment 2311 and the second segment 2312 becomes easier, and the difficulty of manufacturing the first electrode sheet 231 can be reduced.

[0136] 7 shows a schematic diagram of some embodiments of the present application in which a first segment 2311 and a second segment 2312 are connected by a first connecting portion 2314. In some embodiments of the present application, as shown in FIG. 7, the tail portion of the first segment 2311 and the head portion of the second segment 2312 are connected by the first connecting portion 2314.

[0137] The first connecting portion 2314 is a connecting component for connecting the first segment 2311 and the second segment 2312. The first connecting portion 2314 may be an adhesive tape or a separator having an adhesive layer. The first connecting portion 2314 may be made of a material that allows ions to pass through, thereby allowing the first connecting portion 2314 to function as the active material it covers and contribute to improving energy density. The first connecting portion 2314 may be located on either the first segment 2311 or the second segment 2312, or, as shown in FIG. 7, on both the first segment 2311 and the second segment 2312.

[0138] By connecting the first segment 2311 and the second segment 2312 at the first connection part, the first segment 2311 and the second segment 2312 can be positioned, thereby preventing displacement of the first segment 2311 and the second segment 2312. When the first segment 2311 is wound up, the first segment 2311 drives the second segment 2312 via the first connection part 2314, providing the second segment 2312 with the driving force necessary for winding, thereby realizing the first segment 2311 and the second segment 2312 to be wound up in order.

[0139] 8 shows a schematic diagram of the connection between the first segment 2311 and the second segment 2312 and the separator 233 according to some embodiments of the present application. In some embodiments of the present application, as shown in FIGS. 4 and 8, the electrode unit 23 further includes a separator 233 that separates the first electrode sheet 231 and the second electrode sheet 232.

[0140] The separator 233 is disposed between the first electrode sheet 231 and the second electrode sheet 232. The separator 233 is a film-like material that serves as an electrical insulator, and can insulate and separate the first electrode sheet 231 and the second electrode sheet 232, thereby realizing separation between the first electrode sheet 231 and the second electrode sheet 232.

[0141] By isolating the first electrode sheet 231 and the second electrode sheet 232 with the separator 233, it is possible to prevent a short circuit between the first electrode sheet 231 and the second electrode sheet 232, thereby improving safety.

[0142] In some embodiments of the present application, the head portion of the second segment 2312 is connected to the separator 233 .

[0143] By connecting the head portion of the second segment 2312 to the separator 233, the separator 233 can position the head portion of the second segment 2312 relative to the head portion, thereby preventing displacement of the first segment 2311 and the second segment 2312. When forming the electrode unit 23 by winding, the separator 233 drives and winds the head portion of the second segment 2312, and can provide the second segment 2312 with the driving force necessary for winding, thereby enabling the first segment 2311 and the second segment 2312 to be wound in sequence.

[0144] In some embodiments of the present application, both the first segment 2311 and the second segment 2312 are connected to the separator 233, as shown in FIG.

[0145] By connecting the first segment 2311 and the second segment 2312 to the separator 233, the separator 233 can position the first segment 2311 and the second segment 2312, preventing displacement of the first segment 2311 and the second segment 2312. This prevents the risk of a short circuit due to contact between the first electrode sheet 231 and the second electrode sheet 232, and ensures the safety of the battery cell 20 formed by the electrode unit 23.

[0146] 9 shows a schematic diagram of the connection of the first segment 2311 and the second segment 2312 with the separator 233 according to some other embodiments of the present application. In some embodiments of the present application, as shown in FIGS. 4 and 9, the electrode unit 23 includes two separators 233 located on both sides of the first electrode sheet 231, and the first electrode sheet 231 is connected to the two separators 233. In other words, the first segment 2311 and the second segment 2312 are positioned by connecting them with the two separators 233, thereby realizing the positioning of the first segment 2311 and the second segment 2312.

[0147] Fig. 10 shows a schematic diagram of an electrode unit 23 according to some other embodiments of the present application, Fig. 11 shows a schematic diagram of a second electrode sheet 232 according to some embodiments of the present application, and Fig. 12 shows a schematic diagram of a second electrode sheet 232 according to some other embodiments of the present application. In some embodiments of the present application, as shown in Figs. 10 to 12, the second electrode sheet 232 includes a third segment 2321 and a fourth segment 2322, a third active material layer 2321a is disposed in the third segment 2321, a fourth active material layer 2322a is disposed in the fourth segment 2322, and the third segment 2321 is located upstream of the fourth segment 2322 in the winding direction from the inside to the outside.

[0148] The third segment 2321 and the fourth segment 2322 are two parts that make up the second pole sheet 232 and are arranged in the winding direction from the inside to the outside. The third segment 2321 and the fourth segment 2322 may be integrally formed or may be arranged separately. In the winding direction, the third segment 2321 and the fourth segment 2322 may overlap, or the tail portion of the third segment 2321 and the head portion of the fourth segment 2322 may be joined as shown in FIG. 11, or a gap may be provided between the third segment 2321 and the fourth segment 2322 as shown in FIG. 12. Alternatively, the tail portion of the third segment 2321 and the head portion of the fourth segment 2322 may be joined, or a smaller gap may be provided between the third segment 2321 and the fourth segment 2322. In these cases, the third segment 2321 and the fourth segment 2322 do not overlap, so that an increase in the thickness of the electrode unit 23 due to the overlapping portion between the third segment 2321 and the fourth segment 2322 can be prevented, and the space occupied can be reduced.

[0149] The fact that the third segment 2321 is located upstream of the fourth segment 2322 means that when the electrode unit 23 is formed by winding, the third segment 2321 is wound before the fourth segment 2322, and the third segment 2321 is closer to the winding center than the fourth segment 2322.

[0150] The third segment 2321 is a portion of the second electrode sheet 232 located inside the electrode unit 23, i.e., a portion close to the winding center of the second electrode sheet 232. The fourth segment 2322 is a portion of the second electrode sheet 232 located outside the electrode unit 23, i.e., a portion away from the winding center of the second electrode sheet 232. The third segment 2321 has a wound structure and has one or more turns, i.e., the third segment 2321 has at least two curved portions 235. The fourth segment 2322 has a wound structure and has more than one turn, i.e., the fourth segment 2322 has multiple curved portions 235.

[0151] By dividing the second electrode sheet 232 into the third segment 2321 and the fourth segment 2322, different treatments can be applied to the third segment 2321 located on the inner layer and the fourth segment 2322 located on the outer layer, and the third segment 2321 and the fourth segment 2322 can have different physical or chemical properties. Differentiating the inner and outer segments allows the performance of the electrode unit 23 to be better adjusted to meet different usage environments.

[0152] In some embodiments of the present application, the coating density of the third active material layer 2321a is different from the coating density of the fourth active material layer 2322a, and / or the thickness of the third active material layer 2321a is different from the thickness of the fourth active material layer 2322a, and / or the active material material of the third active material layer 2321a is the same as or different from the active material material of the fourth active material layer 2322a.

[0153] The coating density of the third active material layer 2321a refers to the coating weight of the active material of the third active material layer 2321a per unit area. The coating density of the fourth active material layer 2322a refers to the coating weight of the active material of the fourth active material layer 2322a per unit area.

[0154] By adjusting the coating density, thickness and active material recipe of the third active material layer 2321a and the fourth active material layer 2322a and changing the physical or chemical performance of the third segment 2321 and the fourth segment 2322, the electrode unit 23 can meet different performance requirements and satisfy different usage environments.

[0155] In some embodiments of the present application, the coating density of third active material layer 2321a is less than the coating density of fourth active material layer 2322a.

[0156] By making the application density of the third active material layer 2321a smaller than that of the fourth active material layer 2322a, the fracture toughness of the third segment 2321 becomes greater than that of the fourth segment 2322, and cracks or fractures do not easily occur in the curved portion 235 of the third segment 2321. This reduces the incidence of cracks or fractures in the second electrode sheet 232 and improves the safety of the battery cell 20 formed by the electrode unit 23.

[0157] In some embodiments of the present application, the coating density of the fourth active material layer 2322a is 10%-200% greater than the coating density of the third active material layer 2321a.

[0158] When the application density of the fourth active material layer 2322a is H4 and the application density of the third active material layer 2321a is H3, the relationship 0.1≦(H4−H3) / H3≦2 is satisfied.

[0159] By making the application density of the fourth active material layer 2322a greater than that of the third active material layer 2321a, it is possible to ensure that the second electrode sheet 232 contains more active material, and it is possible to ensure that the battery cell 20 formed by the electrode unit 23 has a greater energy density.

[0160] Optionally, the coating density of the fourth active material layer 2322a is 20%-150% greater than the coating density of the third active material layer 2321a.

[0161] Optionally, the coating density of the fourth active material layer 2322a is 40%-120% greater than the coating density of the third active material layer 2321a.

[0162] Optionally, the coating density of the fourth active material layer 2322a is greater than the coating density of the third active material layer 2321a by 30%, 50%, 60%, 70%, 100%, 130%, 150% or 180% or more.

[0163] In some embodiments of the present application, the third active material layer 2321a and the fourth active material layer 2322a may have the same recipe, e.g., the same active material type and active material composition, or the third active material layer 2321a and the fourth active material layer 2322a may have different recipes, e.g., different active material types and active material composition, or the third active material layer 2321a and the fourth active material layer 2322a may have different active material materials, e.g., different chemical systems.

[0164] For example, if the active material of the third active material layer 2321a and the active material of the fourth active material layer 2322a are negative electrode active material, the negative electrode active material may be at least one of graphite (artificial graphite, natural graphite), amorphous carbon (soft carbon, hard carbon, other amorphous carbon), and lithium titanate. For example, if the active material of the third active material layer 2321a and the active material of the fourth active material layer 2322a are positive electrode active material, the positive electrode active material may be at least one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, nickel cobalt manganese oxide, lithium excess lithium manganese oxide, and nickel cobalt aluminum oxide.

[0165] In some embodiments of the present application, the ratio of the thickness of the third active material layer 2321a to the thickness of the fourth active material layer 2322a is 1 / 2-3 / 2.

[0166] When the thickness of the third active material layer 2321a is D3 and the thickness of the fourth active material layer 2322a is D4, the relationship 1 / 2≦D3 / D4≦3 / 2 is satisfied. In other words, the thicknesses of the third active material layer 2321a and the fourth active material layer 2322a are approximately the same.

[0167] For example, D1 / D2 may be 5 / 8, 3 / 4, 7 / 8, 1, 9 / 8, 5 / 4, 1 1 / 8, etc.

[0168] When the coating density of the third active material layer 2321a is smaller than that of the fourth active material layer 2322a and the ratio of the thickness of the third active material layer 2321a to the thickness of the fourth active material layer 2322a satisfies the above range, it is possible to ensure that the third segment 2321 and the fourth segment 2322 are smoothly connected, it is possible to prevent the active material from falling off or being scratched, and it is possible to maintain the quality of the electrode unit 23.

[0169] In some embodiments of the present application, in the winding direction from the inside to the outside, the tail portion of the third segment 2321 and the head portion of the fourth segment 2322 are connected, or as shown in FIG. 12, a gap is provided between the tail portion of the third segment 2321 and the head portion of the fourth segment 2322.

[0170] The tail portion of the third segment 2321 refers to the end portion of the third segment 2321 in the winding direction, i.e., the tail portion of the third segment 2321 refers to the last portion of the third segment 2321. The head portion of the fourth segment 2322 refers to the neck portion of the fourth segment 2322 in the winding direction, i.e., the head portion of the fourth segment 2322 refers to the beginning portion of the fourth segment 2322.

[0171] When the tail portion of the third segment 2321 and the head portion of the fourth segment 2322 are connected, the continuity of the second electrode sheet 232 can be ensured, and the second electrode sheet 232 contains more active material. This ensures a higher energy density of the electrode unit 23. If a gap is provided between the tail portion of the third segment 2321 and the head portion of the fourth segment 2322, the third segment 2321 and the fourth segment 2322 can be easily processed, thereby reducing the difficulty of manufacturing the second electrode sheet 232.

[0172] In some embodiments of the present application, as shown in FIG. 11, the second electrode sheet 232 further includes a second current collector 2323, and the third active material layer 2321a and the fourth active material layer 2322a are each disposed on the second current collector 2323.

[0173] The second current collector 2323 is in the form of a continuous tape, and the third active material layer 2321a and the fourth active material layer 2322a are each disposed on the second current collector 2323. In this case, the third segment 2321 is a portion of the second electrode sheet 232 where the active material layer is applied more densely, and the fourth segment 2322 is a portion of the second electrode sheet 232 where the active material layer is applied more densely. When manufacturing such a second electrode sheet 232, when the active material layer is rolled with rollers, the distance between the pair of rollers is adjusted to change the force with which the pair of rollers roll the second electrode sheet 232, thereby forming the third segment 2321, which is a portion where the active material layer is applied more densely, and the fourth segment 2322, which is a portion where the active material layer is applied more densely.

[0174] In some embodiments of the present application, as shown in FIG. 12 , the second electrode sheet 232 further includes a third current collector segment 2321b and a fourth current collector segment 2322b, and the third active material layer 2321a is disposed on the third current collector segment 2321b to form the third segment 2321, and the fourth active material layer 2322a is disposed on the fourth current collector segment 2322b to form the fourth segment 2322.

[0175] The third current collector segment 2321b and the fourth current collector segment 2322b are two different current collector segments, in this case the third current collector segment 2321b and the fourth current collector segment 2322b are two separate parts.

[0176] Since the third active material layer 2321a is disposed on the third current collector segment 2321b to form the third segment 2321, and the fourth active material layer 2322a is disposed on the fourth current collector segment 2322b to form the fourth segment 2322, the processing and manufacturing of the third segment 2321 and the fourth segment 2322 is facilitated, and the difficulty of manufacturing the second electrode sheet 232 can be reduced.

[0177] 13 is a schematic diagram illustrating some embodiments of the present application in which the third segment 2321 and the fourth segment 2322 are connected by the second connecting portion 2324. In some embodiments of the present application, the tail portion of the third segment 2321 and the head portion of the fourth segment 2322 are connected by the second connecting portion 2324, as shown in FIG.

[0178] The second connecting portion 2324 is a connecting component for connecting the third segment 2321 and the fourth segment 2322. The second connecting portion 2324 may be an adhesive tape or a separator with an adhesive layer. The second connecting portion 2324 may be made of a material that allows ions to pass through, thereby allowing the second connecting portion 2324 to function as the active material it covers and contribute to improving energy density. The second connecting portion 2324 may be located on either the third segment 2321 or the fourth segment 2322, or, as shown in FIG. 13, on both the third segment 2321 and the fourth segment 2322.

[0179] By connecting the third segment 2321 and the fourth segment 2322 at the second connection part 2324, the third segment 2321 and the fourth segment 2322 can be positioned, thereby preventing displacement of the third segment 2321 and the fourth segment 2322. When the third segment 2321 is wound, the third segment 2321 drives the fourth segment 2322 via the second connection part 2324, providing the driving force necessary for winding to the fourth segment 2322, thereby enabling the third segment 2321 and the fourth segment 2322 to be wound in sequence.

[0180] 10 , the electrode unit further includes a separator 233 that separates the first electrode sheet 231 and the second electrode sheet 232. The head portion of the fourth segment 2322 is connected to the separator 233.

[0181] By connecting the head portion of the fourth segment 2322 to the separator 233, the separator 233 can position the fourth segment 2322, thereby preventing displacement between the third segment 2321 and the fourth segment 2322. When winding, the separator 233 drives the head portion of the fourth segment 2322 to wind it up, providing the fourth segment 2322 with the driving force necessary for winding, thereby enabling the third segment 2321 and the fourth segment 2322 to be wound up in order.

[0182] In some embodiments of the present application, the electrode unit 23 comprises two separators 233 each located on either side of the second electrode sheet 232, with the head portion of the second segment 2312 connected to one separator 233 and the head portion of the fourth segment 2322 connected to the other separator 233.

[0183] One separator 233 is connected to the head portion of the second segment 2312, and the other separator 233 is connected to the head portion of the fourth segment 2322, so that one separator 233 can restrict the position of the second segment 2312, and the other separator 233 can restrict the position of the fourth segment 2322. When forming the electrode unit 23 by winding, one separator 233 drives the head portion of the second segment 2312 to wind it up, and can provide the second segment 2312 with the driving force required for winding, so that the first segment 2311 and the second segment 2312 can be wound up in sequence. In addition, the other separator 233 drives the head portion of the fourth segment 2322 to wind it up, and can provide the fourth segment 2322 with the driving force required for winding, so that the third segment 2321 and the fourth segment 2322 can be wound up in sequence.

[0184] 14 shows a schematic diagram of a connection between the first electrode sheet 231 and the second electrode sheet 232 and the separator 233 according to some embodiments of the present application. In some embodiments of the present application, as shown in FIGS. 10 and 14, the electrode unit 23 further includes a separator 233 that separates the first electrode sheet 231 and the second electrode sheet 232, and the third segment 2321 and the fourth segment 2322 are both connected to the separator 233.

[0185] The separator 233 is disposed between the first electrode sheet 231 and the second electrode sheet 232. The separator 233 is a film-like material that serves as an electrical insulator, and can separate the first electrode sheet 231 and the second electrode sheet 232.

[0186] By connecting the third segment 2321 and the fourth segment 2322 to the separator 233, the separator 233 can position the third segment 2321 and the fourth segment 2322, preventing displacement of the third segment 2321 and the fourth segment 2322. This prevents the risk of a short circuit due to contact between the first electrode sheet 231 and the second electrode sheet 232, and ensures the safety of the battery cell 20 formed by the electrode unit 23.

[0187] In some embodiments of the present application, as shown in Figures 10 and 14, the electrode unit 23 has two separators 233 located on either side of the second electrode sheet 232, and the first segment 2311 and the second segment 2312 are both connected to one of the separators 233, and the third segment 2321 and the fourth segment 2322 are both connected to the other of the separators 233.

[0188] When forming the electrode unit 23 by winding, the two separators 233, the first electrode sheet 231, and the second electrode sheet 232 may be stacked in the order of separator 233, first electrode sheet 231, separator 233, and second electrode sheet 232, or in the order of first electrode sheet 231, separator 233, second electrode sheet 232, and separator 233.

[0189] By connecting one separator 233 to the first segment 2311 and the second segment 2312 and connecting the other separator 233 to the third segment 2321 and the fourth segment 2322, it is possible to ensure the positioning of the first segment 2311 and the second segment 2312 by one separator 233 and the positioning of the third segment 2321 and the fourth segment 2322 by the other separator 233. In other words, the positions of the first segment 2311 and the second segment 2312 can be restricted by one separator 233, and the positions of the third segment 2321 and the fourth segment 2322 can be restricted by the other separator 233. This prevents the risk of a short circuit due to contact between the first electrode sheet 231 and the second electrode sheet 232, and ensures the safety of the battery cell 20 formed by the electrode unit 23.

[0190] In some embodiments of the present application, the number of turns in the third segment 2321 is less than the number of turns in the fourth segment 2322.

[0191] The number of turns of the third segment 2321 refers to the number of turns when winding the third segment 2321. One turn refers to the wound portion of the third segment 2321 when starting from a point on the third segment 2321, winding the third segment 2321 in the winding direction, and the third segment 2321 covers the starting point for the first time.

[0192] Similarly, the number of turns of the fourth segment 2322 refers to the number of turns when winding the fourth segment 2322. One turn refers to the wound portion of the fourth segment 2322 when starting from a point on the fourth segment 2322, winding the fourth segment 2322 in the winding direction, and the fourth segment 2322 covers the starting point for the first time.

[0193] The number of turns of the third segment 2321 is set to be fewer than the number of turns of the fourth segment 2322, that is, the number of turns when winding the fourth segment 2322 is set to be greater than the number of turns when winding the third segment 2321. When the coating density of the fourth active material layer 2322a is greater than the coating density of the third active material layer 2321a and the thickness of the electrode unit 23 is the same, winding the fourth segment 2322 with a greater number of turns can ensure that the electrode unit 23 has a higher energy density.

[0194] In some embodiments of the present application, the number of turns of the third segment 2321 is 1 to 5 turns.

[0195] When the number of turns of the third segment 2321 is 1 to 5, it is possible to reduce the incidence of cracks or breaks in the portion close to the winding center of the second electrode sheet 232 and ensure the energy density of the battery cell 20 formed by the electrode unit 23. If the number of turns of the third segment 2321 is too small, cracks or breaks are likely to occur in the curved portion 235 close to the winding center of the second electrode sheet 232, affecting the safety of the battery cell 20 formed by the electrode unit 23. Because the application density of the third active material layer 2321a is low, if the number of turns of the third segment 2321 is too large, it will affect the energy density of the battery cell 20 formed by the electrode unit 23.

[0196] In some embodiments of the present application, the number of turns in the first segment 2311 is less than the number of turns in the second segment 2312 .

[0197] The number of turns of the first segment 2311 refers to the number of turns when winding the first segment 2311. One turn refers to the wound portion of the first segment 2311 when the first segment 2311 starts from a point on the first segment 2311, winds the first segment 2311 in the winding direction, and covers the starting point for the first time.

[0198] Similarly, the number of turns of the second segment 2312 refers to the number of turns when winding the second segment 2312. One turn refers to the wound portion of the second segment 2312 when the second segment 2312 starts from a point on the second segment 2312, winds the second segment 2312 in the winding direction, and covers the starting point for the first time.

[0199] The number of turns of the first segment 2311 is set to be less than the number of turns of the second segment 2312, i.e., the number of turns wound around the second segment 2312 is set to be greater than the number of turns wound around the first segment 2311. If the coating density of the second active material layer 2312a is greater than the coating density of the first active material layer 2311a and the thickness of the electrode unit 23 is the same, winding the second segment 2312 with a greater number of turns can ensure that the electrode unit 23 has a higher energy density.

[0200] In some embodiments of the present application, the number of turns of the first segment 2311 is 1 to 5 turns.

[0201] When the number of turns of the first segment 2311 is 1 to 5, it is possible to reduce the incidence of cracks or breaks in the portion of the first electrode sheet 231 that is close to the winding center, and to ensure the energy density of the battery cell 20 that is formed by the electrode unit 23. If the number of turns of the first segment 2311 is too few, cracks or breaks are likely to occur in the curved portion 235 that is close to the winding center of the first electrode sheet 231, affecting the safety of the battery cell 20 that is formed by the electrode unit 23. If the number of turns of the first segment 2311 is too many, the energy density of the battery cell 20 that is formed by the electrode unit 23 is affected because the application density of the first active material layer 2311a is low.

[0202] In some embodiments of the present application, the present application further provides a battery cell 20 including any one of the electrode units 23 described above.

[0203] In some embodiments of the present application, the present application further provides a battery 100 comprising any one of the battery cells 20 described above.

[0204] In some embodiments of the present application, the present application further provides an electrical equipment comprising any one of the batteries 100 described above for powering the electrical equipment.

[0205] The electrical equipment may be any equipment or system that uses any one of the batteries 100 described above.

[0206] In some embodiments of the present application, as shown in FIGS. 3 to 14 , a battery cell 20 of the present application includes an end cover 21, a case 22, an electrode unit 23, and an electrode terminal 24. The electrode unit 23 is housed in the case 22, and the electrode terminal 24 is disposed in the end cover 21, so that the end cover 21 covers the opening of the case 22. The electrode unit 23 includes a first electrode sheet 231, a second electrode sheet 232, and a separator 233, and is formed by winding the first electrode sheet 231, the separator 233, and the second electrode sheet 232 in a winding direction. The first electrode sheet 231 includes a first segment 2311 and a second segment 2312, and a first active material layer 2311a is disposed in the first segment 2311, and a second active material layer 2312a is disposed in the second segment 2312. In the winding direction from the inside to the outside, the first segment 2311 is located upstream of the second segment 2312. The coating density of the first active material layer 2311a is lower than that of the second active material layer 2312a. The second electrode sheet 232 includes a third segment 2321 and a fourth segment 2322. A third active material layer 2321a is disposed in the third segment 2321, and a fourth active material layer 2322a is disposed in the fourth segment 2322. In the winding direction from the inside to the outside, the third segment 2321 is located upstream of the fourth segment 2322, and the coating density of the third active material layer 2321a is lower than that of the fourth active material layer 2322a. Two separators 233 are provided, and the separators 233 separate the first electrode sheet 231 and the second electrode sheet 232. The first segment 2311 and the second segment 2312 are connected to one separator 233 , and the third segment 2321 and the fourth segment 2322 are connected to the other separator 233 .

[0207] In the electrode unit 23 constituting the battery cell 20, when the application density of the first active material layer 2311a is low and the application density of the third active material layer 2321a is low, the incidence of cracks or breakage in the curved portion 235 approaching the winding center of the first electrode sheet 231 can be reduced, and the incidence of cracks or breakage in the curved portion 235 approaching the winding center of the second electrode sheet 232 can be reduced, thereby improving the safety of the battery cell 20.

[0208] In some embodiments, the present application provides a winding device 400. FIG. 15 shows a schematic diagram of the winding device 400 according to some embodiments of the present application. As shown in FIG. 15, the winding device 400 includes a first providing device 411, a second providing device 412, a separator providing mechanism 42, and a winding mechanism 44. The first providing device 411 is for providing a first electrode sheet 231. As shown in FIGS. 4 to 6, the first electrode sheet 231 includes a first segment 2311 and a second segment 2312. A first active material layer 2311a is disposed on the first segment 2311, and a second active material layer 2312a is disposed on the second segment 2312. The second providing device 412 is for providing a second electrode sheet 232 having a polarity opposite to that of the first electrode sheet 231. The separator providing mechanism 42 is for providing a separator 233. The winding mechanism 44 is installed downstream of the first providing device 411, the second providing device 412, and the separator providing mechanism 42, and is used to wind up the first segment 2311, the second segment 2312, the separator 233, and the second electrode sheet 232 in the winding direction to form the electrode unit 23. Among them, the first providing device 411 is configured to provide the first electrode sheet 231 so that the first segment 2311 enters the winding mechanism 44 first and the second segment 2312 enters the winding mechanism 44 after the first segment 2311.

[0209] In this application, the terms upstream and downstream refer to a chronological relationship in the winding process of the electrode unit 23. For example, the winding mechanism 44 being installed downstream of the first providing device 411, the second providing device 412, and the separator providing mechanism 42 means that, in the winding process, the first electrode sheet 231 provided by the first providing device 411 is transported to the winding mechanism 44, the second electrode sheet 232 provided by the second providing device 412 is transported to the winding mechanism 44, the separator 233 provided by the separator providing mechanism 42 is transported to the winding mechanism 44, and the first segment 2311, the second segment 2312, the separator 233, and the second electrode sheet 232 are wound in the winding direction by the winding mechanism 44 to form the electrode unit 23.

[0210] The first electrode sheet 231 (first segment 2311 and second segment 2312), separator 233, and second electrode sheet 232 are stacked and wound up to form the electrode unit 23. The separator 233 is disposed between the first electrode sheet 231 and the second electrode sheet 232 to separate the first electrode sheet 231 and the second electrode sheet 232. This makes it possible to prevent a short circuit due to contact between the first electrode sheet 231 and the second electrode sheet 232.

[0211] The winding mechanism 44 includes a rotating disk and a winding shaft, and the rotating disk rotates the winding shaft to wind up the first polar sheet 231, the separator 233, and the second polar sheet 232 onto the winding shaft.

[0212] In the winding device 400 of the embodiment of the present application, the winding mechanism 44 winds the first segment 2311, the second segment 2312, the separator 233, and the second electrode sheet 232 to form the electrode unit 23, so that the first segment 2311 and the second segment 2312 can be treated differently, and the first segment 2311 and the second segment 2312 can have different physical or chemical properties. Differentiating the inside and outside allows for better adjustment of the performance of the electrode unit 23.

[0213] In some embodiments of the present application, the coating density of the first active material layer 2311a is different from the coating density of the second active material layer 2312a, and / or the thickness of the first active material layer 2311a is different from the thickness of the second active material layer 2312a, and / or the active material material of the first active material layer 2311a is the same as or different from the active material material of the second active material layer 2312a.

[0214] By adjusting the coating density, thickness and active material composition of the first active material layer 2311a and the second active material layer 2312a and changing the physical or chemical properties of the first segment 2311 and the second segment 2312, the electrode unit 23 can meet different performance requirements and satisfy different usage environments.

[0215] In some embodiments of the present application, the coating density of first active material layer 2311a is less than the coating density of second active material layer 2312a.

[0216] By making the application density of the first active material layer 2311a smaller than that of the second active material layer 2312a, the fracture toughness of the first segment 2311 becomes greater than that of the second segment 2312, and cracks or breaks do not easily occur in the curved portion 235 of the first segment 2311. This reduces the incidence of cracks or breaks in the first electrode sheet 231 and improves the safety of the battery cell 20 formed by the electrode unit 23.

[0217] In some embodiments of the present application, the first providing device 411 comprises a first sub-providing mechanism 411a and a second sub-providing mechanism 411b, where the first sub-providing mechanism 411a provides the first segment 2311 and the second sub-providing mechanism 411b provides the second segment 2312.

[0218] The first sub-providing mechanism 411a is an unwinding roller, and provides the first segment 2311 of the first pole sheet 231. The second sub-providing mechanism 411b is an unwinding roller, and provides the second segment 2312 of the first pole sheet 231. In this case, the first segment 2311 and the second segment 2312 are independent of each other.

[0219] Optionally, to improve productivity, two first sub-supply mechanisms 411a and two second sub-supply mechanisms 411b may be installed, which can meet the material supply requirements of the first segment 2311 and the second segment 2312 and ensure the progress of material supply for the first pole sheet 231, thereby reducing the material replacement time.

[0220] In some embodiments of the present application, the separator 233 includes a first separator 233a and a second separator 233b, and the separator providing mechanism 42 provides the first separator 233a and the second separator 233b. The winding device 400 further includes a first combining mechanism 431, which is located downstream of the first providing device 411 and the separator providing mechanism 42. The first combining mechanism 431 combines the first separator 233a, the first polar sheet 231, and the second separator 233b to form a first polar sheet unit. The first providing device 411 is configured to provide the first polar sheet 231 so that the first segment 2311 enters the first combining mechanism 431 first and the second segment 2312 enters the first combining mechanism 431 after the first segment 2311. The winding mechanism 44 is installed downstream of the first composite mechanism 431, and winds up the first electrode sheet unit and the second electrode sheet 232 in the winding direction to form the electrode unit 23.

[0221] The first composite mechanism 431 includes a pair of first composite rollers. The first separator 233a, the first pole sheet 231, and the second separator 233b are rolled by the pair of first composite rollers, thereby connecting the first pole sheet 231 to the first separator 233a and the second separator 233b, and forming a first pole sheet unit.

[0222] The first segment 2311 enters the first composite mechanism 431 first, the second segment 2312 enters the first composite mechanism 431 after the first segment 2311, the first segment 2311 is connected to the first separator 233a and the second separator 233b first, and the second segment 2312 is connected to the first separator 233a and the second separator 233b after the first segment 2311, so that the first segment 2311 is located upstream of the second segment 2312 in the winding direction from the inside to the outside.

[0223] The first separator 233a, the first electrode sheet 231, and the second separator 233b are combined to form a first electrode sheet unit, i.e., the first electrode sheet 231 is connected to the first separator 233a and the second separator 233b. In this case, the first separator 233a and the second separator 233b serve to position the first electrode sheet 231, sandwich the second segment 2312, drive and wind the second segment 2312, and provide the driving force necessary for winding to the second segment 2312, thereby realizing sequential winding of the first segment 2311 and the second segment 2312. The first electrode sheet 231 can be transported by transporting the first separator 233a and the second separator 233b, ensuring stable transport of the first segment 2311 and the second segment 2312.

[0224] In some embodiments of the present application, the first providing device 411 further comprises a first connecting mechanism (not shown) that connects the tail portion of the first segment 2311 and the head portion of the second segment 2312 at a first connecting portion.

[0225] The first connecting portion may be an adhesive tape, and the first connecting mechanism may be an adhesive application mechanism. The adhesive application mechanism includes an adhesive tape providing assembly, a mechanical claw for clamping the adhesive tape, and a moving assembly for driving the mechanical claw. The mechanical claw attaches the adhesive tape to the first segment 2311 and the second segment 2312, thereby connecting the adhesive tape to the tail portion of the first segment 2311 and the head portion of the second segment 2312.

[0226] When the first segment 2311 and the second segment 2312 are connected at the first connection part, when the first segment 2311 is wound up, the first segment 2311 drives the second segment 2312 via the first connection part, and can provide the second segment 2312 with the driving force necessary for winding, so that the first segment 2311 and the second segment 2312 can be wound up in sequence.

[0227] In another embodiment, the first connecting portion may be an adhesive, and the first connecting mechanism may be an adhesive application mechanism. The first connecting mechanism applies adhesive to the tail portion of the first segment 2311 and the head portion of the second segment 2312, thereby connecting the tail portion of the first segment 2311 and the head portion of the second segment 2312 with the adhesive.

[0228] 15, 16, and 17. FIG. 16 is a schematic diagram illustrating a first transport mechanism 451 according to some embodiments of the present application when located at the first transport position, and FIG. 17 is a schematic diagram illustrating a second transport mechanism 452 according to some embodiments of the present application when located at the first transport position. In some embodiments of the present application, as shown in FIGS. 15 to 17, the winding device 400 further includes a first transport mechanism 451, a second transport mechanism 452, and a first adjustment mechanism 453. The first transport mechanism 451 is located between the first sub-providing mechanism 411a and the first combining mechanism 431, and is configured to transport the first segment 2311 to the first combining mechanism 431 at the first transport position. The second transport mechanism 452 is located between the second sub-providing mechanism 411b and the first combining mechanism 431, and is configured to transport the second segment 2312 to the first combining mechanism 431 at the first transport position. The first adjustment mechanism 453 is connected to the first transport mechanism 451 and the second transport mechanism 452, and is used to move the first transport mechanism 451 or the second transport mechanism 452 to the first transport position.

[0229] The first transport mechanism 451 and the second transport mechanism 452 may have a similar configuration. Both the first transport mechanism 451 and the second transport mechanism 452 may include transport rollers and a transport plate. Each of the first segment 2311 and the second segment 2312 is transported by the corresponding transport rollers and transport plate.

[0230] The first transport position refers to a position where the first electrode sheet 231 faces the first composite mechanism 431, and is a position where the first electrode sheet 231 is transported to the first composite mechanism 431 and connected to the separator 233 by the first composite mechanism 431.

[0231] The first adjustment mechanism 453 may be, for example, a linear drive mechanism such as a hydraulic cylinder, an air cylinder, or an electric push rod, or may be a drive mechanism including a motor and a transmission assembly. The transmission assembly may be a gear rack, a screw nut, or another transmission assembly. Alternatively, the first adjustment mechanism 453 may be another drive mechanism such as a rotating disk. In this case, the first transfer mechanism 451 and the second transfer mechanism 452 are both connected to a rotating disk, and the rotating disk rotates the first transfer mechanism 451 and the second transfer mechanism 452 to move them to the first transfer position.

[0232] 16, when the first transport mechanism 451 is located at the first transport position, the first transport mechanism 451 transports the first segment 2311 to the first combined mechanism 431, and at this time, the second transport mechanism 452 is located at the first retracted position so as not to interfere with the first transport mechanism 451. As shown in FIG. 17, when the second transport mechanism 452 is located at the first transport position, the second transport mechanism 452 transports the second segment 2312 to the first combined mechanism 431, and at this time, the first transport mechanism 451 is located at the second retracted position so as not to interfere with the second transport mechanism 452. The second retracted position and the first retracted position are located on both sides of the first transport position, that is, the first retracted position, the first transport position, and the second retracted position are installed in this order on the operating trajectory of the first adjustment mechanism 453.

[0233] By adjusting the positions of the first conveying mechanism 451 and the second conveying mechanism 452 with the first adjustment mechanism 453, it is possible to use the first conveying mechanism 451 to convey the first segment 2311 to the first combined mechanism 431, or to use the second conveying mechanism 452 to convey the second segment 2312 to the first combined mechanism 431. This ensures the conveying efficiency of the first electrode sheet 231 and the productivity of the electrode unit 23.

[0234] It is also possible to have one first adjustment mechanism 453, in which case the first adjustment mechanism 453 synchronously adjusts the positions of the first transport mechanism 451 and the second transport mechanism 452. Alternatively, there may be two first adjustment mechanisms 453, in which one first adjustment mechanism 453 adjusts the position of the first transport mechanism 451 and the other first adjustment mechanism 453 adjusts the position of the second transport mechanism 452.

[0235] 15 to 17, in some embodiments of the present application, the winding device 400 further includes a first buffer mechanism 461 and a second buffer mechanism 462. The first buffer mechanism 461 is installed between the first sub-providing mechanism 411a and the first adjusting mechanism 453, and holds the first segment 2311 to ensure continuous supply of material to the first segment 2311 when the first adjusting mechanism 453 adjusts the position of the first conveying mechanism 451. The second buffer mechanism 462 is installed between the second sub-providing mechanism 411b and the first adjusting mechanism 453, and holds the second segment 2312 to ensure continuous supply of material to the second segment 2312 when the first adjusting mechanism 453 adjusts the position of the second conveying mechanism 452.

[0236] Alternatively, the first buffer mechanism 461 and the second buffer mechanism 462 may each be a lever swing type buffer mechanism having a plurality of swing levers. The first pole sheet can be held by adjusting the distance between two adjacent swing levers to change the length of the corresponding portion of the first pole sheet in the buffer mechanism.

[0237] 15 to 17, the winding device 400 further includes a first EPC mechanism 471 and a second EPC mechanism 472. The first EPC mechanism 471 is installed between the first sub-providing mechanism 411a and the first transport mechanism 451, and is used to adjust the meandering of the first segment 2311 so as to maintain the transport accuracy of the first segment 2311. The second EPC mechanism 472 is installed between the second sub-providing mechanism 411b and the first transport mechanism 451, and is used to adjust the meandering of the second segment 2312 so as to maintain the transport accuracy of the second segment 2312. The first EPC mechanism 471 and the second EPC mechanism 472 can refer to conventional EPC devices, and will not be described in detail in the present application.

[0238] In some embodiments of the present application, as shown in Figures 15 to 17, a first cutting mechanism 481 is installed upstream of the first combining mechanism 431. The first cutting mechanism 481 cuts the first segment 2311 or the second segment 2312 in order to adjust the positions of the first conveying mechanism 451 and the second conveying mechanism 452 using the first adjusting mechanism 453. The first cutting mechanism 481 can refer to a conventional cutting device and will not be described in detail in the present application.

[0239] 15 to 17, the winding device 400 further includes a first image measuring system 491 and a first pre-winding EPC mechanism 492. The first image measuring system 491 and the first pre-winding EPC mechanism 492 are installed between the first combining mechanism 431 and the winding mechanism 44. The first image measuring system 491 acquires image information of the first electrode sheet 231 and the separator 233 combined by the first combining mechanism 431, and the first pre-winding EPC mechanism 492 is used to adjust the meandering of the first electrode sheet 231 and the separator 233. The first image measuring system 491 may be a CCD (charge coupled device) camera, and the first pre-winding EPC mechanism 492 may refer to a conventional EPC device and will not be described in detail in this application.

[0240] 15 to 17, the winding device 400 further includes a first pre-winding tension system 511. The first pre-winding tension system 511 is installed upstream of the winding mechanism 44 and adjusts the tension of the first pole sheet 231. The first pre-winding tension system 511 includes a first tension roller and a first adjustment component, and the first adjustment component adjusts the position of the first tension roller to change the tension of the first pole sheet 231.

[0241] FIG. 18 is a schematic diagram illustrating the configuration of a winding device 400 according to some other embodiments of the present application. In some embodiments of the present application, as shown in FIG. 18 and FIGS. 10 to 12, the second electrode sheet 232 includes a third segment 2321 and a fourth segment 2322. A third active material layer 2321a is provided on the third segment 2321, and a fourth active material layer 2322a is provided on the fourth segment 2322. The second providing device 412 is configured to provide the second electrode sheet 232 so that the third segment 2321 enters the winding mechanism 44 first, and the fourth segment 2322 enters the winding mechanism 44 after the third segment 2321.

[0242] The third segment 2321 and the fourth segment 2322 are subjected to different treatments, so that the third segment 2321 and the fourth segment 2322 have different physical or chemical properties. The differentiation between the inside and outside allows the performance of the electrode unit 23 to be better adjusted.

[0243] In some embodiments of the present application, the coating density of the third active material layer 2321a is different from the coating density of the fourth active material layer 2322a, and / or the thickness of the third active material layer 2321a is different from the thickness of the fourth active material layer 2322a, and / or the active material material of the third active material layer 2321a is the same as or different from the active material material of the fourth active material layer 2322a.

[0244] By adjusting the coating density, thickness and active material recipe of the third active material layer 2321a and the fourth active material layer 2322a and changing the physical or chemical performance of the third segment 2321 and the fourth segment 2322, the electrode unit 23 can meet different performance requirements and satisfy different usage environments.

[0245] In some embodiments of the present application, the coating density of third active material layer 2321a is less than the coating density of fourth active material layer 2322a.

[0246] The second electrode sheet 232 includes a third segment 2321 and a fourth segment 2322, and by making the application density of the third active material layer 2321a smaller than the application density of the fourth active material layer 2322a, the fracture toughness of the third segment 2321 is greater than the fracture toughness of the fourth segment 2322, and cracks or fractures do not easily occur in the curved portion 235 of the third segment 2321. This reduces the incidence of cracks or fractures in the second electrode sheet 232 and improves the safety of the battery cell 20 composed of the electrode unit 23.

[0247] In some embodiments of the present application, as shown in FIG. 18, the second providing device 412 includes a third sub-providing mechanism 412a and a fourth sub-providing mechanism 412b, where the third sub-providing mechanism 412a provides the third segment 2321 and the fourth sub-providing mechanism 412b provides the fourth segment 2322.

[0248] The third sub-providing mechanism 412a is an unwinding roller, and provides the third segment 2321 of the second pole sheet 232. The fourth sub-providing mechanism 412b is an unwinding roller, and provides the fourth segment 2322 of the second pole sheet 232. In this case, the third segment 2321 and the fourth segment 2322 are independent of each other.

[0249] Optionally, to improve productivity, two third sub-supply mechanisms 412a and two fourth sub-supply mechanisms 412b may be installed, which can meet the material supply requirements of the third segment 2321 and the fourth segment 2322 while ensuring the progress of material supply for the second pole sheet 232, thereby reducing the material replacement time.

[0250] In some embodiments of the present application, the separator 233 includes a first separator 233a and a second separator 233b, and the winding device 400 includes two separator providing mechanisms 42. One separator providing mechanism 42 provides the first separator 233a, and the other separator providing mechanism 42 provides the second separator 233b. The winding device 400 further includes a first combining mechanism 431 and a second combining mechanism 432. The first combining mechanism 431 is located downstream of the first providing device 411 and one of the separator providing mechanisms 42. The first combining mechanism 431 combines the first electrode sheet 231 and the first separator 233a to form a first electrode sheet unit. The second combining mechanism 432 is located downstream of the second providing device 412 and the other separator providing mechanism 42. The second combining mechanism 432 combines the second electrode sheet 232 and the second separator 233b to form a second electrode sheet unit. The first providing device 411 is configured to provide the first electrode sheet 231 such that the first segment 2311 enters the first combining mechanism 431 first and the second segment 2312 enters the first combining mechanism 431 after the first segment 2311. The winding mechanism 44 is installed downstream of the first combining mechanism 431 and the second combining mechanism 432, and winds up the first electrode sheet unit and the second electrode sheet unit in the winding direction to form the electrode unit 23.

[0251] The first combining mechanism 431 combines the first electrode sheet 231 and the first separator 233a to form a first electrode sheet unit, thereby enabling the first separator 233a to position the first electrode sheet 231, and the second combining mechanism 432 combines the second electrode sheet 232 and the second separator 233b to form a second electrode sheet unit, thereby enabling the second separator 233b to position the second electrode sheet 232. This ensures that the first electrode sheet 231 and the second electrode sheet 232 in the electrode unit 23 formed by winding are isolated by the first separator 233a and the second separator 233b. This prevents short circuits due to contact between the first electrode sheet 231 and the second electrode sheet 232, ensuring the safety of the battery cell 20 formed by the electrode unit 23.

[0252] The first polar sheet 231 and the first separator 233a are combined to form a first polar sheet unit. The first segment 2311 is combined with the first separator 233a first, and the second segment 2312 is combined with the first separator 233a after the first segment 2311. The first separator 233a provides the driving force necessary for winding the first segment 2311 and the second segment 2312, and the first segment 2311 and the second segment 2312 are wound in order by the driving of the first separator 233a.

[0253] In an embodiment in which the second pole sheet 232 includes a third segment 2321 and a fourth segment 2322, the second providing device 412 is configured to provide the second pole sheet 232 such that the third segment 2321 enters the second combining mechanism 432 first and the fourth segment 2322 enters the second combining mechanism 432 after the third segment 2321. By having the third segment 2321 enter the second combining mechanism 432 first and the fourth segment 2322 enter the second combining mechanism 432 after the third segment 2321, and by connecting the third segment 2321 to the second separator 233b first and the fourth segment 2322 to the second separator 233b after the third segment 2321, the third segment 2321 is located upstream of the fourth segment 2322 in the winding direction from the inside to the outside.

[0254] The second polar sheet 232 and the second separator 233b are combined to form a second polar sheet unit. The third segment 2321 is combined with the second separator 233b first, and the fourth segment 2322 is combined with the second separator 233b after the third segment 2321. The second separator 233b provides the driving force necessary for winding the third segment 2321 and the fourth segment 2322, and the third segment 2321 and the fourth segment 2322 are wound in order by driving the second separator 233b.

[0255] 18, 19, and 20. FIG. 19 is a schematic diagram illustrating a third transport mechanism 454 according to some embodiments of the present application when positioned at the second transport position, and FIG. 20 is a schematic diagram illustrating a fourth transport mechanism 455 according to some embodiments of the present application when positioned at the second transport position. In some embodiments of the present application, as shown in FIGS. 18 to 20, the winding device 400 further includes a third transport mechanism 454, a fourth transport mechanism 455, and a second adjustment mechanism 456. The third transport mechanism 454 is located between the third sub-providing mechanism 412a and the second combining mechanism 432, and is configured to transport the third segment 2321 to the second combining mechanism 432 at the second transport position. The fourth transport mechanism 455 is located between the fourth sub-providing mechanism 412b and the second combining mechanism 432, and is configured to transport the fourth segment 2322 to the second combining mechanism 432 at the second transport position. The second adjustment mechanism 456 is connected to the third transport mechanism 454 and the fourth transport mechanism 455, and is used to move the third transport mechanism 454 or the fourth transport mechanism 455 to the second transport position.

[0256] The third transport mechanism 454 and the fourth transport mechanism 455 may have a similar configuration. Both the third transport mechanism 454 and the fourth transport mechanism 455 may include transport rollers and a transport plate. The third segment 2321 and the fourth segment 2322 are transported by the corresponding transport rollers and transport plate, respectively.

[0257] The second transport position refers to a position where the second electrode sheet 232 faces the second composite mechanism 432, and is a position where the second electrode sheet 232 is transported to the second composite mechanism 432 and connected to the separator 233 by the second composite mechanism 432.

[0258] The second adjustment mechanism 456 may be, for example, a linear drive mechanism such as a hydraulic cylinder, an air cylinder, or an electric push rod, or may be a drive mechanism including a motor and a transmission assembly. The transmission assembly may be a gear rack, a screw nut, or another transmission assembly. Alternatively, the second adjustment mechanism 456 may be another drive mechanism such as a rotating disk. In this case, the third transfer mechanism 454 and the fourth transfer mechanism 455 are both connected to a rotating disk, and the rotating disk rotates the third transfer mechanism 454 and the fourth transfer mechanism 455 to move them to the second transfer position.

[0259] 19, when the third transport mechanism 454 is located at the second transport position, the third transport mechanism 454 transports the third segment 2321 to the second combined mechanism 432, and at this time, the fourth transport mechanism 455 is located at the third retracted position so as not to interfere with the third transport mechanism 454. As shown in FIG. 20, when the fourth transport mechanism 455 is located at the second transport position, the fourth transport mechanism 455 transports the fourth segment 2322 to the second combined mechanism 432, and at this time, the third transport mechanism 454 is located at the fourth retracted position so as not to interfere with the fourth transport mechanism 455. The fourth retracted position and the third retracted position are located on both sides of the second transport position, that is, the third retracted position, the second transport position, and the fourth retracted position are located in that order on the operating trajectory of the second adjustment mechanism 456.

[0260] By adjusting the positions of the third conveying mechanism 454 and the fourth conveying mechanism 455 with the second adjustment mechanism 456, it is possible to use the third conveying mechanism 454 to convey the third segment 2321 to the second combined mechanism 432, or to use the fourth conveying mechanism 455 to convey the fourth segment 2322 to the second combined mechanism 432. This ensures the conveying efficiency of the first electrode sheet 231 and the productivity of the electrode unit 23.

[0261] It is also possible to have one second adjustment mechanism 456, in which case the second adjustment mechanism 456 synchronously adjusts the positions of the third transport mechanism 454 and the fourth transport mechanism 455. Alternatively, there may be two second adjustment mechanisms 456, in which one second adjustment mechanism 456 adjusts the position of the third transport mechanism 454, and the other second adjustment mechanism 456 adjusts the position of the fourth transport mechanism 455.

[0262] In some embodiments of the present application, the winding device 400 further includes a third buffer mechanism 463 and a fourth buffer mechanism 464. The third buffer mechanism 463 is installed between the third sub-providing mechanism 412a and the second adjusting mechanism 456 and holds the third segment 2321 to ensure a continuous supply of material to the third segment 2321 when the second adjusting mechanism 456 adjusts the position of the third conveying mechanism 454. The fourth buffer mechanism 464 is installed between the fourth sub-providing mechanism 412b and the second adjusting mechanism 456 and holds the fourth segment 2322 to ensure a continuous supply of material to the fourth segment 2322 when the second adjusting mechanism 456 adjusts the position of the fourth conveying mechanism 455.

[0263] Alternatively, the third buffer mechanism 463 and the fourth buffer mechanism 464 may each be a lever swing type buffer mechanism having multiple swing levers. The distance between two adjacent swing levers is adjusted to change the length of the corresponding second pole sheet in the buffer mechanism, thereby achieving retention of the second pole sheet.

[0264] 18 to 20 , the winding device 400 further includes a third EPC mechanism 473 and a fourth EPC mechanism 474. The third EPC mechanism 473 is installed between the third sub-providing mechanism 412a and the third transport mechanism 454, and is used to adjust the meandering of the third segment 2321 so as to maintain the transport accuracy of the third segment 2321. The fourth EPC mechanism 474 is installed between the fourth sub-providing mechanism 412b and the third transport mechanism 454, and is used to adjust the meandering of the fourth segment 2322 so as to maintain the transport accuracy of the fourth segment 2322. The third EPC mechanism 473 and the fourth EPC mechanism 474 can refer to conventional EPC devices, and will not be described in detail in the present application.

[0265] In some embodiments of the present application, as shown in Figures 18 to 20, a second cutting mechanism 482 is installed upstream of the second combining mechanism 432. The second cutting mechanism 482 cuts the third segment 2321 or the fourth segment 2322 so that the second adjusting mechanism 456 can adjust the positions of the third conveying mechanism 454 and the fourth conveying mechanism 455. The second cutting mechanism 482 can refer to a conventional cutting device and will not be described in detail in this application.

[0266] 18 to 20, the winding device 400 further includes a second image measuring system 493 and a second pre-winding EPC mechanism 494. The second image measuring system 493 and the second pre-winding EPC mechanism 494 are installed between the second combining mechanism 432 and the winding mechanism 44. The second image measuring system 493 acquires image information of the second electrode sheet 232 and the separator 233 combined by the second combining mechanism 432, and the second pre-winding EPC mechanism 494 is used to adjust the meandering of the second electrode sheet 232 and the separator 233. The second image measuring system 493 may be a CCD camera, and the second pre-winding EPC mechanism 494 may refer to a conventional EPC device and will not be described in detail in the present application.

[0267] 18 to 20 , the winding device 400 further includes a second pre-winding tension system 512. The second pre-winding tension system 512 is installed upstream of the winding mechanism 44 and adjusts the tension of the second pole sheet 232. The second pre-winding tension system 512 includes a second tension roller and a second adjustment component, and the second adjustment component adjusts the position of the second tension roller to change the tension of the second pole sheet 232.

[0268] 15 to 20, the winding device 400 further includes a separator cutter 52, an end shaping roller 53, and an adhesive application roller 54. The separator cutter 52, the end shaping roller 53, and the adhesive application roller 54 are all installed near the winding mechanism 44. The separator cutter 52 cuts the separator 233 after the electrode unit 23 has been formed by winding, the end shaping roller 53 rolls the electrode unit 23 formed by winding to prevent the electrode unit 23 from loosening, and the adhesive application roller 54 applies adhesive for shaping the end to the electrode unit 23 formed by winding.

[0269] In some embodiments of the present application, a compaction workstation 55 is typically provided downstream of the winding mechanism 44 to compact the electrode units 23 formed by winding, thereby ensuring that the battery cells 20 formed by the electrode units 23 have a higher energy density.

[0270] The electrode unit 23 and the winding device according to the embodiment of the present application have been described above. The winding method according to the embodiment of the present application will now be described, with reference to the above embodiments for parts not described.

[0271] 21 shows a schematic flow diagram of a winding method 600 according to some embodiments of the present application. As shown in FIG. 21, the winding method 600 includes the following steps:

[0272] Step 601: Provide a first electrode sheet 231 including a first segment 2311 and a second segment 2312, with a first active material layer 2311a disposed on the first segment 2311 and a second active material layer 2312a disposed on the second segment 2312.

[0273] Step 602: Provide a second polar sheet 232 that is opposite in polarity to the first polar sheet 231.

[0274] Step 603: Provide a separator 233.

[0275] Step 604: First wind up the first segment 2311, the separator 233 and the second electrode sheet 232, and then wind up the second segment 2312, the separator 233 and the second electrode sheet 232 in the winding direction to form the electrode unit 23.

[0276] In addition, in "Step 604: Winding up the first segment 2311, the second segment 2312, the separator 233 and the second polar sheet 232 in the winding direction", the first segment 2311 is located upstream of the second segment 2312 in the winding direction from the inside to the outside.

[0277] In some embodiments of the present application, the coating density of the first active material layer 2311a is different from the coating density of the second active material layer 2312a, and / or the thickness of the first active material layer 2311a is different from the thickness of the second active material layer 2312a, and / or the active material material of the first active material layer 2311a is the same as or different from the active material material of the second active material layer 2312a.

[0278] In some embodiments of the present application, the coating density of first active material layer 2311a is less than the coating density of second active material layer 2312a.

[0279] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto, and parts therein may be replaced with equivalents, without departing from the scope of the present application. In particular, the technical features recited in each embodiment may be combined in any manner, provided that no structural contradiction exists. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions within the scope of the claims. [Explanation of symbols]

[0280] 100 batteries 10. Cabinet 11 First sub-enclosure 12 Second sub-enclosure 20 battery cells 21 End cover 22 cases 23 Electrode unit 231 First Pole Sheet 2311 1st Segment 2311a 1st active material layer 2311b First collector segment 2312 Second Segment 2312a Second active material layer 2312b Second collector segment 2313 First current collector 2314 First connection part 232 Second Pole Sheet 2321 Third Segment 2321a Third active material layer 2321b Third collector segment 2322 4th segment 2322a 4th active material layer 2322b 4th collector segment 2323 Second current collector 233 Separator 233a First separator 233b Second separator 2324 Second connection part 234 Flat area 235 Curved section 24 electrode terminal 200 Controller 300 motor 400 Winding device 411 First providing device 411a First Sub-Provision Organization 411b Second Sub-Provision Organization 412 Second providing device 412a Third Sub-Provision Organization 412b Fourth Sub-Provisional Organization 42 Separator providing mechanism 431 1st Complex Mechanism 432 Second complex mechanism 44 Winding mechanism 451 First conveying mechanism 452 Second transport mechanism 453 1st adjustment mechanism 454 Third Transfer Mechanism 455 Fourth Transport Mechanism 456 Second adjustment mechanism 461 First buffer mechanism 462 Second buffer mechanism 463 Third Buffer Mechanism 464 4th Buffer Mechanism 471 1st EPC Organization 472 2nd EPC Organization 473 3rd EPC Organization 474 4th EPC Organization 481 1st cutting mechanism 482 Second cutting mechanism 491 First Image Measuring System 492 First pre-winding EPC mechanism 493 Second Image Measuring System 494 Second pre-winding EPC mechanism 511 First pre-winding tension system 512 Second pre-winding tension system 52 Separator cutter 53 End shaping roller 54 Adhesive application roller 55 Consolidation Workstation 1000 vehicles

Claims

1. An electrode unit, a first electrode sheet and a second electrode sheet having opposite polarities, the first electrode sheet and the second electrode sheet being stacked and wound in a winding direction to form the electrode unit; the first electrode sheet includes a first segment and a second segment, a first active material layer is disposed in the first segment, a second active material layer is disposed in the second segment, the first segment is located upstream of the second segment in the winding direction from the inside to the outside, a coating density of the first active material layer is different from a coating density of the second active material layer, the first electrode sheet further includes a first current collector, the first active material layer and the second active material layer are each disposed on the first current collector; The electrode unit further includes a separator that separates the first electrode sheet from the second electrode sheet, the first segment is connected to the separator, An electrode unit in which a head portion of the second segment located most upstream in the winding direction from the inside to the outside is connected to the separator, and the separator realizes positioning of the second segment relative to the head portion.

2. The electrode unit according to claim 1 , wherein the coating density of the first active material layer is lower than the coating density of the second active material layer.

3. The electrode unit according to claim 1 , wherein the thickness of the first active material layer is different from the thickness of the second active material layer.

4. 4. The electrode unit according to claim 3, wherein the ratio of the thickness of the first active material layer to the thickness of the second active material layer is 1 / 2 to 3 / 2.

5. The electrode unit according to claim 1 , wherein the active material of the first active material layer is the same as or different from the active material of the second active material layer.

6. 2. The electrode unit according to claim 1, wherein, in the winding direction from the inside to the outside, the tail portion of the first segment and the head portion of the second segment are connected, or a gap is provided between the tail portion of the first segment and the head portion of the second segment.

7. 2. The electrode unit according to claim 1, wherein the first electrode sheet further comprises a first current collector segment and a second current collector segment, the first active material layer being disposed on the first current collector segment to form the first segment, and the second active material layer being disposed on the second current collector segment to form the second segment.

8. The electrode unit according to claim 7 , wherein the tail portion of the first segment and the head portion of the second segment are connected by a first connecting portion.

9. 2. The electrode unit according to claim 1, wherein the second electrode sheet comprises a third segment and a fourth segment, a third active material layer is disposed in the third segment, a fourth active material layer is disposed in the fourth segment, and the third segment is located upstream of the fourth segment in the winding direction from the inside to the outside.

10. The coating density of the third active material layer is different from the coating density of the fourth active material layer, and / or the thickness of the third active material layer is different from the thickness of the fourth active material layer, and / or The active material of the third active material layer is the same as or different from the active material of the fourth active material layer. The electrode unit according to claim 9 .

11. 11. The electrode unit according to claim 10, wherein the ratio of the thickness of the third active material layer to the thickness of the fourth active material layer is 1 / 2 to 3 / 2.

12. 10. The electrode unit of claim 9, wherein the tail portion of the third segment and the head portion of the fourth segment are connected in the winding direction from the inside to the outside, or a gap is provided between the tail portion of the third segment and the head portion of the fourth segment.

13. The electrode unit according to claim 12 , wherein the second electrode sheet further comprises a second current collector, and the third active material layer and the fourth active material layer are each disposed on the second current collector.

14. 13. The electrode unit according to claim 12, wherein the second electrode sheet further comprises a third current collector segment and a fourth current collector segment, the third active material layer being disposed on the third current collector segment to form the third segment, and the fourth active material layer being disposed on the fourth current collector segment to form the fourth segment.

15. The electrode unit according to claim 14 , wherein the tail portion of the third segment and the head portion of the fourth segment are connected by a second connecting portion.

16. The electrode unit according to claim 9 , further comprising a separator separating the first electrode sheet and the second electrode sheet, the head portion of the fourth segment being connected to the separator.

17. The electrode unit according to claim 16, wherein the electrode unit comprises two separators located on either side of the second electrode sheet, and the head portion of the second segment is connected to one of the separators, and the head portion of the fourth segment is connected to the other of the separators.

18. The electrode unit according to any one of claims 9 to 17, wherein the number of turns of the third segment is smaller than the number of turns of the fourth segment.

19. The electrode unit according to any one of claims 1 to 17, wherein the number of turns of the first segment is smaller than the number of turns of the second segment.

20. 18. The electrode unit according to claim 1, wherein the coating density of the second active material layer is 10% to 200% greater than the coating density of the first active material layer.

21. A battery cell comprising the electrode unit according to any one of claims 1 to 17.

22. A battery comprising the battery cell of claim 21.

23. 23. An electrical installation comprising the battery of claim 22.

24. a first providing device for providing a first electrode sheet including a first segment and a second segment, a first active material layer disposed on the first segment, a second active material layer disposed on the second segment, the first active material layer having a coating density different from that of the second active material layer, and a first current collector, the first active material layer and the second active material layer being respectively disposed on the first current collector; a second providing device for providing a second polar sheet having a polarity opposite to that of the first polar sheet; a separator providing mechanism that provides a separator; a first combining mechanism located downstream of the first providing device and the separator providing mechanism, which combines the first electrode sheet and the separator to form a first electrode sheet unit; a winding mechanism that is installed downstream of the first providing device, the second providing device, and the separator providing mechanism, and that winds up the first segment, the second segment, the separator, and the second electrode sheet in a winding direction to form an electrode unit, the first providing device is configured to provide the first pole sheet such that the first segment enters the winding mechanism first and the second segment enters the winding mechanism after the first segment; the first composite mechanism is configured to connect the first segment to the separator, connect a head portion of the second segment located most upstream in a winding direction from the inside to the outside to the separator, and realize positioning of the second segment with respect to the head portion by the separator; The first providing device is a winding device having a first connection mechanism that connects the tail portion of the first segment and the head portion of the second segment at a first connection portion.

25. the thickness of the first active material layer is different from the thickness of the second active material layer, and / or The active material of the first active material layer is the same as or different from the active material of the second active material layer.

25. The winding device of claim 24.

26. the second electrode sheet includes a third segment and a fourth segment, a third active material layer is disposed in the third segment, and a fourth active material layer is disposed in the fourth segment; The second presenting device is configured to present the second pole sheet so that the third segment enters the winding mechanism first and the fourth segment enters the winding mechanism after the third segment.

26. A winding device according to claim 24 or 25.

27. The coating density of the third active material layer is different from the coating density of the fourth active material layer, and / or the thickness of the third active material layer is different from the thickness of the fourth active material layer, and / or The active material of the third active material layer is the same as or different from the active material of the fourth active material layer.

27. The winding device of claim 26.

28. the separator includes a first separator and a second separator, and the separator providing mechanism provides the first separator and the second separator; the first combining mechanism is for combining the first separator, the first polar sheet, and the second separator to form a first polar sheet unit; the first providing device is configured to provide the first pole sheet so that the first segment enters the first compound mechanism first and the second segment enters the first compound mechanism after the first segment; The winding mechanism is installed downstream of the first composite mechanism and winds up the first electrode sheet unit and the second electrode sheet in a winding direction to form an electrode unit.

25. The winding device of claim 24.

29. the separator includes a first separator and a second separator, the winding device includes two separator providing mechanisms, one of the separator providing mechanisms provides the first separator and the other of the separator providing mechanisms provides the second separator; The winding device further comprises: a second combining mechanism that is located downstream of the second providing device and the other separator providing mechanism and combines the second electrode sheet and the second separator to form a second electrode sheet unit; the first providing device is configured to provide the first pole sheet so that the first segment enters the first compound mechanism first and the second segment enters the first compound mechanism after the first segment; The winding mechanism is installed downstream of the first composite mechanism and the second composite mechanism, and winds up the first electrode sheet unit and the second electrode sheet unit in a winding direction to form an electrode unit.

25. The winding device of claim 24.

30. providing a first electrode sheet including a first segment and a second segment, a first active material layer disposed on the first segment, a second active material layer disposed on the second segment, the coating density of the first active material layer being different from the coating density of the second active material layer, and further including a first current collector, the first active material layer and the second active material layer being respectively disposed on the first current collector; providing a second polar sheet having a polarity opposite to that of the first polar sheet; providing a separator; connecting the first segment to the separator, and connecting the head portion of the second segment located most upstream in the winding direction from the inside to the outside to the separator, thereby realizing positioning of the second segment relative to the head portion by the separator; and winding the first segment, the second segment, the separator, and the second electrode sheet in a winding direction such that the first segment, the separator, and the second electrode sheet are wound first, and then the second segment, the separator, and the second electrode sheet are wound after the first segment, to form an electrode unit. Winding method.

31. the thickness of the first active material layer is different from the thickness of the second active material layer, and / or The active material of the first active material layer is the same as or different from the active material of the second active material layer. The winding method according to claim 30.

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