Separator, electrode assembly, separator production method, separator production apparatus, and battery

Abstract

This application relates to a separator, electrode assembly, separator manufacturing method, separator manufacturing equipment, and battery. The separator includes a substrate and a coating. The substrate extends longitudinally. The coating extends in the same direction as the substrate and is applied to at least one surface of the substrate in the thickness direction. The coating is divided into thick coating areas and thin coating areas along the width direction of the substrate. Thick coating areas are arranged on both sides of the thin coating areas, and the thin coating areas are recessed relative to the thick coating areas. Each thick coating area has multiple indentations, which are spaced apart along the extension direction of the separator, and each indentation extends from one end of its respective thick coating area to the other end in the width direction. In this application, the coating enhances the adhesion between the separator and the electrode. The design of the thin coating areas and indentations simultaneously increases the gap between the separator and the electrode, providing a channel for electrolyte wetting, accelerating electrolyte wetting efficiency, increasing electrolyte storage capacity, and thus improving the cycle life of the battery.

Description

Technical Field

[0001] This application relates to the field of battery manufacturing technology, and in particular to separators, electrode assemblies, separator production methods, separator production equipment, and batteries. Background Technology

[0002] Electrode assemblies are prone to opening due to temperature drop after hot pressing, resulting in poor adhesion between the electrode and separator. This can lead to electrode misalignment during subsequent processing, reducing yield. To address this, related technologies involve thickly coating the separator with an adhesive layer to enhance adhesion between the separator and electrode. While this method improves the adhesion between the electrode and separator, it is costly, and excessively tight adhesion hinders electrolyte wetting and penetration, leading to a decrease in individual battery cell performance. Summary of the Invention

[0003] Based on this, in order to improve the adhesion between the electrode and the separator and the permeation efficiency of the electrolyte, this application proposes a separator, an electrode assembly, a separator manufacturing method, a separator manufacturing equipment, and a battery.

[0004] In a first aspect, this application proposes a diaphragm, comprising: Substrate, extending longitudinally; The coating extends in the same direction as the substrate and is applied to at least one side surface of the substrate in the thickness direction. The coating is divided into a thick coating area and a thin coating area along the width direction of the substrate. The thick coating area is arranged on both sides of the thin coating area and is recessed relative to the thick coating area. Each of the thick coating areas is provided with a plurality of indentations, which are spaced apart along the extension direction of the diaphragm, and each indentation extends from one end of the thick coating area in the width direction to the other end.

[0005] In some embodiments, the diaphragm has a first extended end, and the interval between adjacent indentations is the indentation spacing; Wherein, the spacing between the indentations in each of the thick coating areas increases gradually along the extension direction of the diaphragm toward the first extension end; or, the spacing between the indentations in each of the thick coating areas decreases first and then increases along the extension direction of the diaphragm toward the first extension end.

[0006] In some embodiments, the spacing between the indentations in each of the thick-coated areas increases progressively toward the first extension end of the diaphragm along its extension direction; or... The diaphragm is divided into multiple isolation segments along its extension direction. The indentation spacing of each isolation segment is equal, and the indentation spacing of adjacent isolation segments increases gradually at the first extension end of the diaphragm along its extension direction.

[0007] In some embodiments, the maximum thickness of the thick coating area is a, the width of the thick coating area is c, the depth of the indentation is T, the length of the indentation is L, the minimum thickness of the thin coating area is b, and the diaphragm satisfies at least one of the following conditions: T is negatively correlated with L; a≥T≥b; L≥c; 20mm < c < 80mm; 1μm≤a≤10μm; 0.5μm≤b≤3μm; 20mm≤L≤80mm.

[0008] In some embodiments, the thick coating areas located at the two sides of the diaphragm are respectively the first thick coating area and the second thick coating area; Wherein, the depth of the indentation in both the first thick coating area and the second thick coating area decreases gradually along the width direction of the substrate toward the side where the adjacent thin coating area is located; and / or, The distribution density of the indentations in the first thick coating area is greater than the distribution density of the indentations in the second thick coating area; and / or, The length of the indentation in the first thick coating area is greater than the length of the indentation in the second thick coating area; and / or, The thickness of both the first thick coating area and the second thick coating area decreases from the edge of the diaphragm towards the adjacent thin coating area; and / or, The thickness of the thin coating area gradually decreases from both ends to the middle along the width direction, and the thin coating area and the thick coating areas on both sides are set with the same thickness at the boundary position.

[0009] In some embodiments, the end of the indentation away from the thin coating area extends to the edge of the thick coating area, or the end of the indentation near the thin coating area extends beyond the thick coating area and into the adjacent thin coating area.

[0010] In some embodiments, the indentation is a continuously arranged groove structure, and the bottom wall surface of the indentation near the thin coating area is flush with or lower than the surface of the thin coating area.

[0011] In some embodiments, the indentations extend continuously in an arch shape, and all the indentations arch in the same direction away from the first extension end of the diaphragm.

[0012] In some embodiments, the indentation extends continuously in the form of a straight strip.

[0013] In some embodiments, the indentation comprises a plurality of dimples arranged intermittently along its extension direction.

[0014] In some embodiments, the projection of the indentation along the thickness direction is polygonal or crescent-shaped.

[0015] Secondly, this application proposes an electrode assembly, comprising: A positive electrode, a negative electrode, and at least one separator as described in the first aspect, the separator being separated between the positive electrode and the negative electrode.

[0016] In some embodiments, the electrode assembly is a wound structure, wherein the gap between the indentations in the thick coating area of ​​each diaphragm increases in a gradient along the winding direction of the diaphragm, and the first extension end of the diaphragm is located at its winding tail end.

[0017] In some embodiments, each of the diaphragms is wound to form multiple turns of first isolation segments, wherein in every two adjacent turns of the first isolation segments, the indentation spacing of the first isolation segments located on the inner turn is smaller than the indentation spacing of the first isolation segments located on the outer turn.

[0018] In some embodiments, the indentation spacing of the first isolation segment in each lap is a first spacing J1, where J1 increases linearly with the increase of m, where d1 ranges, d2 ranges, and m is the number of laps in which the first isolation segment is located, and 10≤m≤100.

[0019] In some embodiments, each of the diaphragms is wound to form multiple turns of the first isolation segment, the multiple turns of the first isolation segment being divided into multiple groups of isolation groups from the inside to the outside, and each group of isolation groups including multiple turns of the first isolation segment arranged adjacently. The indentation spacing of the first isolation segment in the same group is equal, and the indentation spacing of different isolation groups increases sequentially from the inside to the outside.

[0020] In some embodiments, the electrode assembly includes a flat region and a bent region, with the bent region provided on both sides of the flat region, and the indentation located in the flat region.

[0021] In some embodiments, the electrode assembly is a stacked structure, and the spacing between the indentations of each diaphragm shows a trend of first decreasing and then increasing along the stacking direction of the electrode assembly.

[0022] In some embodiments, each of the diaphragms includes multiple layers of second isolation segments disposed along the stacking direction. The indentation spacing of each layer of the second isolation segment is a second spacing J2. J2 changes with the increase of n, first decreasing and then increasing. dn is the layer number where the second isolation segment is located, and 10≤n≤100.

[0023] In some embodiments, the negative electrode sheet is disposed on both sides of the membrane along its width direction, corresponding to the thick coating area on the membrane; and / or, All the indentations in the thick coating area are arched in the same direction, and the edge of the negative electrode overlaps with the arch point of the indentation.

[0024] Thirdly, this application proposes a method for producing a diaphragm, comprising: A blank is provided, which is divided into a thick coating area and a thin coating area along its width direction. The thick coating area is located at the edge of the blank, and the thick coating area is arranged on both sides of the thin coating area. The thin coating area is recessed relative to the thick coating area. The blank is unwound, and rollers are used to press multiple indentations on each of the thick coating areas at intervals. The indentations extend from one end of the thick coating area in the width direction to the other end to obtain a diaphragm.

[0025] In some embodiments, unwinding the billet includes: The conveyor speed V1 of the billet and the linear speed V2 of the roller are adjusted according to preset rules; wherein, the preset rules include one of the following conditions: controlling k to increase continuously, controlling k to increase intermittently, and controlling k to decrease first and then increase, and k = V1:V2.

[0026] Fourthly, this application provides a diaphragm production apparatus, comprising: The unwinding mechanism, the winding mechanism, and the roller mechanism include roller groups, each roller group including a pair of rollers arranged opposite each other, the two pairs of rollers being spaced apart to form a belt travel gap, and the rollers being provided with a pressing portion for forming indentations, the pressing portion extending from one end of the roller axially upward to the other end. The diaphragm production equipment is capable of performing the diaphragm production method as described in the third aspect.

[0027] In some embodiments, the roller includes a base and a rolling portion, the rolling portion being disposed on the base; The roller pressing section is arranged in multiple portions at intervals along the rotation direction of the roller; and / or, The roller pressing section extends continuously and is arched in its plane of rotation; and / or, Along the axial direction of the roller, the projection of the outer contour of the substrate falls within the range of the equivalent cylinder coaxial with the substrate.

[0028] In some embodiments, the roller mechanism further includes an adjustment assembly, the roller being mounted on the adjustment assembly, the adjustment assembly being used to adjust the size of the belt travel gap between the roller and the roller.

[0029] Fifthly, this application proposes a battery including the electrode assembly described in the second aspect.

[0030] Compared with the prior art, this application has the following beneficial effects: The aforementioned separator, electrode assembly, separator manufacturing method, separator manufacturing equipment, and battery feature a coating that enhances the adhesion between the separator and the electrode. The thin coating area and recessed design also increase the gap between the separator and the electrode, providing a channel for electrolyte wetting, accelerating electrolyte wetting efficiency, increasing electrolyte storage capacity, and thus improving the battery's cycle life. Attached Figure Description

[0031] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 The diagram shows the external shape of a single battery cell in some embodiments. Figure 2 for Figure 1 The diagram shows an exploded view of a single battery cell. Figure 3 A front view of the diaphragm in some embodiments; Figure 4 A top view of the diaphragm in some embodiments; Figure 5 This is a partial cross-sectional schematic diagram of the diaphragm in some embodiments; Figure 6 This is a schematic diagram of the structure of a wound electrode assembly according to some embodiments; Figure 7 These are schematic diagrams of the stacked electrode assembly in some embodiments; Figure 8 This is a schematic diagram of the stacking of the separator and negative electrode sheet in some embodiments; Figure 9 This is a schematic flowchart of a membrane production method according to some embodiments; Figure 10 This is a schematic diagram of the composition of a diaphragm production equipment according to some embodiments; Figure 11 Schematic diagram of roller assembly for some embodiments Figure 12 This is a schematic diagram of the roller mechanism in some embodiments.

[0032] The reference numerals in the detailed embodiments are as follows: 1000, Battery; 100, Electrode assembly; Q1, Straight area; Q2, Bending area; 10, Separator; Y, Extension direction; Z, Thickness direction; X, Width direction; D1, First extension end; G, Separator section; G1, First separator section; G2, Second separator section; 11, Substrate; 12, Coating; 12a, Thick coating area; a1, First thick coating area; a2, Second thick coating area; 12b, Thin coating area; 12c, Indentation; J, Indentation spacing; 20, Positive electrode sheet; 30, Negative electrode sheet; 2000, Separator production equipment; 2100, Unwinding mechanism; 2200, Rewinding mechanism; 2300, Roller mechanism; 2310, Roller; 2311, Substrate; 2312, Roller pressing section; 2313, Power component; P, Blank; 2400, Tensioning mechanism; 2320, Adjustment component. Detailed Implementation

[0033] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0034] In the description of this application, it should be understood that, where they appear, the terms “center,” “longitudinal,” “lateral,” “length,” “width,” “thickness,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0035] Furthermore, where applicable, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0036] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," "fixing," etc., shall be interpreted broadly. For example, they may refer to a fixed connection, a detachable connection, or an integral part; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; they may refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0037] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0038] It should be noted that, if an element is described as "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is described as "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0039] To improve the adhesion between the separator and the electrode and to ensure the wetting effect of the electrolyte, embodiments of this application propose a separator, an electrode assembly, a separator manufacturing method, a separator manufacturing equipment, and a battery.

[0040] The electrode assembly in this embodiment is formed by stacking a positive electrode, a negative electrode, and a separator. The separator is disposed between the positive and negative electrode, serving as insulation and providing an ion transport channel. The electrode assembly is the core component of the battery, used to realize the electrochemical reaction of the battery, and can be a wound structure or a stacked structure.

[0041] A battery can be a single battery cell or a battery module or battery pack containing multiple battery cells. A single battery cell can be a hard-case battery or a pouch battery.

[0042] Figure 1 The diagram shows the external shape of a battery cell in some embodiments. Figure 2 for Figure 1The diagram shows an exploded view of a single battery cell.

[0043] In some embodiments, combined with Figure 1 and Figure 2 The battery 1000 cell includes a casing, a top cover assembly, and an electrode assembly 100. The casing and top cover assembly together form an internal space for housing the electrode assembly 100. Specifically, the casing may have a cavity within it, with at least one end open. The top cover assembly closes the opening of the casing to seal the cavity, and the electrode assembly 100 is housed within the cavity. The casing may be, but is not limited to, a metal casing, such as an aluminum casing or a steel casing. An electrolyte is injected into the battery 1000 cell, and the electrolyte wets the interior of the electrode assembly 100, providing ion migration pathways for electrochemical reactions and serving a conductive function.

[0044] The diaphragm 10 of this application is described in detail below.

[0045] Figure 3 This is a front view of the diaphragm 10 in some embodiments. Figure 4 This is a top view of the diaphragm 10 in some embodiments. It is noteworthy that... Figure 4 The length of the diaphragm 10 in its extension direction Y is only for illustration and is not a limitation on its actual length.

[0046] Please refer to Figure 3 and Figure 4 The diaphragm 10 in this embodiment includes a substrate 11 and a coating 12. The substrate 11 extends longitudinally. The coating 12 extends in the same direction as the substrate 11 and is applied to at least one side surface of the substrate 11 in the thickness direction Z. The coating 12 is divided into a thick coating area 12a and a thin coating area 12b along the width direction X of the substrate 11. The thick coating area 12a is arranged on both sides of the thin coating area 12b, and the thin coating area 12b is recessed relative to the thick coating area 12a. Each thick coating area 12a is provided with a plurality of indentations 12c, which are spaced apart along the extension direction Y of the diaphragm 10. Each indentation 12c extends from one end of the thick coating area 12a in the width direction X to the other end.

[0047] The substrate 11 is a microporous insulating material used to provide ion migration channels and can be made of materials such as polyethylene and polyolefin. The coating 12 is used to optimize the performance of the diaphragm 10, for example, to improve at least one of the following: thermal stability, high temperature resistance, mechanical properties, interfacial compatibility, wettability, and ion transport efficiency of the diaphragm 10. Specifically, the coating 12 can contain one or more of the following materials: ceramics (such as alumina and magnesium oxide), polyvinylidene fluoride (PVDF), polyacrylate (PA), polyacrylic acid (PAA), polyimide (PI), and ionic polymers (such as lithium diaphragm and polyelectrolytes).

[0048] The substrate 11 has a smaller dimension along its thickness direction Z. The coating 12 is disposed on one or both sides of the substrate 11 layer in the thickness direction Z and extends in the same direction as the substrate 11, with the extension direction Y corresponding to the extension direction Y of the diaphragm 10. The width direction X, extension direction Y, and thickness direction Z of the substrate 11 layer are perpendicular to each other.

[0049] The coating 12 is divided into a thick coating area 12a and a thin coating area 12b along the width direction X of the substrate 11. The thin coating area 12b is located in the middle, with thick coating areas 12a on both sides. The thin coating area 12b is recessed relative to the thick coating area 12a, meaning that the maximum thickness of the thin coating area 12b is less than or equal to the minimum thickness of the thick coating area 12a, and the average thickness of the thin coating area 12b is less than the average thickness of the thick coating area 12a. Typically, the thick coating area 12a is of uniform thickness throughout the width direction X of the substrate 11. In one example, the thick coating area 12a and the thin coating area 12b are of uniform thickness throughout, and their average thickness is less than the thickness of the thick coating area 12a. In another example, the thick coating area 12a is of uniform thickness throughout, the thickness of the thin coating area is equal to that of the thick coating area 12a on both sides, and the overall thickness of the thin coating area 12b decreases from both sides towards the middle.

[0050] A recess 12c is provided in the thick coating area 12a. The recess 12c is a groove structure recessed into the surface of the thick coating area 12a. The recess 12c extends from one end of the thick coating area 12a along the width direction X of the substrate 11 to the other end. This means that both ends of the recess 12c extend towards the two ends of the thick coating area 12a along the width direction X of the substrate 11. The two ends of the recess 12c can be spaced apart from the edges of the thick coating area 12a, or they can penetrate the edges of the thick coating area 12a along the width direction X of the substrate 11, and may even extend beyond the boundary between the thick coating area 12a and the thin coating area 12b into the thin coating area 12b. The extension trajectory of the recess 12c can be a straight line, a curve, or a closed line (such as a square line or a circular line). The recesses 12c on the same thick coating area 12a are spaced apart along the extension direction Y of the diaphragm 10 (i.e., the extension direction Y of the substrate 11 and the coating 12). The extension trajectory shape of the recesses 12c on the same thick coating area 12a is usually the same.

[0051] When the aforementioned separator 10 is applied to the battery 1000, the coating 12 enhances the adhesion between the separator 10 and the electrode. The design of the thin coating area 12b and the indentation 12c simultaneously increases the gap between the separator 10 and the electrode, providing a channel for electrolyte wetting, accelerating the electrolyte wetting efficiency, increasing the electrolyte storage capacity, and thus improving the cycle life of the battery 1000.

[0052] It is worth noting that the indentation 12c can be a notch (obtained by removing a portion of the material) or an indentation (obtained by pressing material to the sides or under the recessed area without material removal). In one embodiment, the indentation 12c is an indentation. For example, the indentation 12c is obtained by rolling, and the compaction density of the indented area is greater than the compaction density of other areas of the coating 12. When the indentation 12c is an indentation, the thick coating area 12a is locally compacted, which enhances the edge structural strength of the diaphragm 10 and effectively avoids the problem of edge folding of the diaphragm 10 during winding / stacking.

[0053] In some embodiments, the diaphragm 10 has a first extended end D1, and the spacing between adjacent indentations 12c is the indentation spacing J. The indentation spacing J of each thick coating area 12a increases gradually along the extension direction Y of the diaphragm 10 toward the first extended end D1, or the indentation spacing J of each thick coating area 12a exhibits a decreasing-then-increasing trend along the extension direction Y of the diaphragm 10 toward the first extended end D1.

[0054] Combination Figure 4 Understanding: Indentation spacing J refers to the shortest distance between adjacent indentations 12c along the extension direction Y of the diaphragm 10. Indentation spacing J varies gradually along the extension direction Y of the diaphragm 10, or it varies in a gradual manner, either by the indentation spacing J changing continuously between every two adjacent indentations 12c, or by dividing the indentations 12c into multiple groups, each group containing several sequentially adjacent indentations 12c, with equal indentation spacing J between indentations 12c within the same group and unequal indentation spacing J between indentations 12c in different groups, i.e., the indentation spacing J exhibits a step-like variation.

[0055] The electrode assembly 100 can be a wound structure or a stacked structure. When the diaphragm 10 is applied to the wound electrode assembly 100, its first extension end D1 is located at the wound tail end of the electrode assembly 100. When the diaphragm 10 is applied to the stacked electrode assembly 100, its first extension end D1 is located at the stacked top end of the electrode assembly 100.

[0056] For the wound electrode assembly 100, its inner ring is more difficult to wet with electrolyte than its outer ring. In this case, the indentation spacing J of each thick coating area 12a is gradually increased towards the first extension end D1, so that the indentations 12c of the diaphragm 10 located in the inner ring of the electrode assembly 100 are more densely distributed than the indentations 12c of the diaphragm 10 located in the outer ring of the electrode assembly 100. This provides more channels for the electrolyte to wet the inner ring of the electrode assembly 100, thereby improving the wetting effect of the inner ring of the electrode assembly 100.

[0057] For the stacked electrode assembly 100, in the stacking direction, the central region is more difficult to wet with electrolyte than the two end edges. In this case, the indentation spacing J of each thick coating area 12a decreases and then increases towards the first extension end D1, resulting in a denser distribution of indentations 12c on the diaphragm 10 in the central region of the electrode assembly 100 compared to those on the end regions. This provides more channels for electrolyte to wet the central region of the electrode assembly 100, improving the wetting effect in the central region.

[0058] In some embodiments, the indentation spacing J of each thick coating area 12a varies sequentially along the extension direction Y of the diaphragm 10 toward the first extension end D1 of the diaphragm 10 according to an increasing rule or a rule of first decreasing and then increasing. That is, the indentation spacing J between any two adjacent indentations 12c is not equal.

[0059] At this time, the indentation spacing J changes continuously, which can more accurately match the electrolyte wetting requirements at different positions of the diaphragm 10 and improve the wetting uniformity.

[0060] In some embodiments, the diaphragm 10 is divided into multiple isolation segments G along its extension direction Y. The indentation spacing J of each isolation segment G is equal, and the indentation spacing J of adjacent isolation segments G changes gradually along the extension direction Y of the diaphragm 10 toward the first extension end D1 of the diaphragm 10 in an increasing or decreasing manner.

[0061] Understandably, each isolation segment G is provided with multiple indentations 12c, and the indentation spacing J between any two adjacent indentations 12c is equal.

[0062] At this point, the segmented adjustment of the dent spacing J of dent 12c by the isolation segment G helps to reduce processing complexity and reduce costs.

[0063] Figure 5 This is a partial cross-sectional schematic diagram of the diaphragm 10 in some embodiments.

[0064] In some embodiments, combined with Figure 5 Understand that the maximum thickness of the thick coating region 12a is a, the width of the thick coating region 12a is c, the depth of the indentation 12c is T, the length of the indentation 12c is L, the minimum thickness of the thin coating region 12b is b, and the diaphragm 10 satisfies at least one of the following conditions: T is negatively correlated with L; a≥T≥b; L≥c; 20mm < c < 80mm; 1μm≤a≤10μm; 0.5μm≤b≤3μm; 20mm≤L≤80mm.

[0065] Wherein, the length L of the dent 12c is the dimension of the dent 12c along the width direction X of the substrate 11. The depth T of the dent 12c is the maximum distance between the dent 12c and the outer surface of the thick coating area 12a along the thickness direction Z of the substrate 11, that is, the maximum depth of the dent 12c.

[0066] The depth T of the dent 12c is negatively correlated with its length L. If the dent 12c is too long and deep, the disruption to the structural continuity of the thick coating area 12a will be more severe, which is not conducive to the structural reliability of the thick coating area 12a and the adhesion between the diaphragm 10 and the electrode.

[0067] The maximum thickness 'a' of the thick coating region 12a is the maximum dimension of the thick coating region 12a along the thickness direction Z of the substrate 11. The minimum thickness 'b' of the thin coating region 12b is the minimum dimension of the thin coating region 12b along the thickness direction Z of the substrate 11.

[0068] When a ≥ T ≥ b, it means that the maximum depth of the indentation 12c is not less than the minimum thickness of the thin coating area 12b, nor does it exceed the maximum thickness of the thick coating area 12a. On the one hand, a ≥ T requires that the depth T of the indentation 12c must not exceed the maximum thickness of the thick coating area 12a, so as not to damage the substrate 11 of the separator 10, avoid the coating 12 from falling off, and ensure the electrochemical performance and mechanical safety of the battery 1000. On the other hand, T ≥ b requires that the depth T of the indentation 12c must not be less than the minimum thickness of the thin coating area 12b, so as not to make the depth of the indentation 12c too small, which would not be able to effectively play the role of the ion transport channel, especially when the indentation 12c is an indentation, so as to avoid the indentation depth being too small and thus failing to effectively enhance the reliability of the edge structure of the separator 10.

[0069] If 'a' is too large, not only will the material consumption be high, but the separator 10 will also occupy more space in the electrode assembly 100, which is not conducive to the control of the capacity and volume of the electrode assembly 100. If 'a' is too small, the coating 12 will be too thin, the adhesion between the separator 10 and the electrode will be weak, the structure of the electrode assembly 100 will be loose and prone to misalignment and scrap, and the yield of the battery 1000 will be reduced. When 1μm≤a≤10μm, the material consumption of the coating 12 is reasonable, and the adhesion, capacity and volume control of the electrode assembly 100 are balanced, ensuring the yield of the battery 1000. Specifically, 'a' can take values ​​of 1μm, 2μm, 5μm, 8μm, 10μm, and any value between adjacent values.

[0070] If b is too large, the recessed space formed by the thin coating area 12b will be too small, weakening its effect on improving electrolyte wetting. Also, if b is too large, the connection strength between the thin coating area 12b and the thick coating areas 12a on both sides will be weak, which is detrimental to the overall structural strength of the diaphragm 10 coating 12. When 0.5μm ≤ b ≤ 3μm, both electrolyte wetting effect and the overall strength of the diaphragm 10 coating 12 can be balanced. Specifically, b can take values ​​of 0.5μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, and any values ​​between adjacent values.

[0071] The width *c* of the thick coating area 12a refers to its dimension along the width direction *X* of the substrate 11. If *c* is too large, it will encroach on the distribution space of the thin coating area 12b, causing the separator 10 to adhere too tightly to the electrode, reducing the electrolyte wetting effect. The separator 10 is mainly bonded to the electrode through the thick coating area 12a. If *c* is too small, the bonding area between the separator 10 and the electrode will be insufficient, resulting in a loose structure of the electrode assembly 100, which is prone to misalignment and failure, reducing the yield of the battery 1000. When 20 mm < *c* < 80 mm, it not only ensures the tightness of the bonding between the separator 10 and the electrode but also helps to ensure ion transport efficiency, thereby ensuring electrolyte wetting efficiency. Specifically, *c* can take values ​​of 21 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 79 mm, and any values ​​between adjacent values.

[0072] When L=c, it can generally be understood that the indentation 12c extends to both ends of the thick coating area 12a in the width direction X, and the length L of the indentation 12c is equal to the width c of the thick coating area 12a. Furthermore, the indentation 12c can also extend beyond the edge of the thick coating area 12a to the thin coating area 12b, i.e., L>c. In this way, the indentation 12c effectively connects the thin coating area 12b and the outside of the diaphragm 10, ensuring the unobstructed flow of the ion transport channel.

[0073] If L is too long, it will damage the overall structural reliability of coating 12. If L is too short, the effect of improving the electrolyte wetting effect will not be significant. When 20mm≤L≤80mm, it can not only significantly improve the electrolyte wetting effect, but also ensure the overall structural strength of coating 12.

[0074] In some embodiments, the thick coating areas 12a located at the two edges of the diaphragm 10 are respectively a first thick coating area a1 and a second thick coating area a2. The first thick coating area a1 and the second thick coating area a2 may be adjacent to the same thin coating area 12b, or they may be adjacent to different thin coating areas 12b. This is mainly because, during the fabrication stage, multiple coating units can be simultaneously coated on the same substrate 11, and each coating unit includes a thin coating area 12b and thick coating areas 12a located on both sides of the thin coating area 12b. The thick coating areas 12a of two adjacent coating units may be coated adjacently or spaced apart. When multiple coating units are simultaneously coated on the diaphragm 10, a diaphragm 10 containing one coating unit is subsequently obtained by the same slitting method for application to the electrode assembly 100.

[0075] In some embodiments, combined with Figure 5 It is understood that the depth of the indentation 12c in both the first thick coating area a1 and the second thick coating area a2 decreases along the width direction X of the substrate 11 toward the side where the adjacent thin coating area 12b is located.

[0076] That is, the depth of the indentation 12c on the first thick coating area a1 and the second thick coating area a2 located at the edge of the diaphragm 10 gradually decreases from the edge of the diaphragm 10 towards the thin coating area 12b. The indentation 12c has a concave bottom surface located in the thickness direction Z of its substrate 11, and the concave bottom surface gradually increases from the edge of the diaphragm 10 towards the thin coating area 12b.

[0077] The edge of the diaphragm 10 is the weakest point, most prone to folding and tearing. The depth of the indentation 12c is greatest at this point. When the indentation 12c is an indentation, its effect on strengthening the diaphragm 10 is more significant. The gradual change in the depth of the indentation 12c allows the stress distribution to transition smoothly from the edge to the thin-coated area 12b, reducing the occurrence of cracks.

[0078] In some embodiments, the distribution density of the indentations 12c in the first thick coating area a1 is greater than the distribution density of the indentations 12c in the second thick coating area a2.

[0079] When applied to a single battery cell (1000), the first thick coating area a1 is located on top of the separator 10, and the second thick coating area a2 is located at the bottom of the separator 10. After the electrolyte is injected into the single battery cell (1000), the electrolyte is deposited at the bottom of the single battery cell casing under gravity, closer to the second thick coating area a2, allowing the electrolyte to quickly wet the bottom of the electrode assembly 100. Conversely, the first thick coating area a1 is farther from the bottom of the casing, resulting in a longer electrolyte wetting path and slower wetting speed at the top of the electrode assembly 100.

[0080] At this time, the indentations 12c of the first thick coating area a1 are more densely distributed to provide more electrolyte wetting channels. The wetting speed of the top area of ​​the electrode assembly 100 makes the electrolyte wetting of the electrode assembly 100 more uniform.

[0081] In some embodiments, the length of the indentation 12c in the first thick coating area a1 is greater than the length of the indentation 12c in the second thick coating area a2.

[0082] When the length of the indentation 12c in the first thick coating area a1 is greater than the length of the indentation 12c in the second thick coating area a2, the rapid wetting path of the electrolyte on the top of the electrode assembly 100 is extended, which can accelerate the wetting speed of the top area of ​​the electrode assembly 100.

[0083] In some embodiments, combined with Figure 5 It is understood that the thickness of both the first thick coating area a1 and the second thick coating area a2 is set to decrease from the edge of the diaphragm 10 to the adjacent thin coating area 12b.

[0084] At this point, the thickness of coating 12 gradually changes from the thick coating area 12a to the thin coating area 12b. On the one hand, the thick coating area 12a at the edge provides stronger mechanical support, improving the tear resistance and folding resistance of the diaphragm 10 at the edge. On the other hand, the thickness of the thick coating area 12a gradually decreases towards the thin coating area 12b, avoiding stress concentration caused by thick edges, reducing crack formation, making the stress on the edge of the diaphragm 10 more uniform, and also facilitating the wetting of the electrolyte towards the center of the electrode assembly 100.

[0085] In some embodiments, combined with Figure 5 It is understood that the thickness of the thin coating area 12b gradually decreases from both ends to the middle along the width direction X, and the thin coating area 12b and the thick coating areas 12a on both sides are set with the same thickness at the boundary position.

[0086] On the one hand, the thin coating area 12b is thick at both ends and gradually thins towards the middle, smoothly transitioning to the boundary with the thick coating areas 12a on both sides, making the thickness change of the entire diaphragm 10 smoother, avoiding stress concentration points caused by abrupt changes in thickness, and reducing the risk of edge folding, wrinkling and cracking of the diaphragm 10 during winding / stacking.

[0087] On the other hand, the thinner coating area 12b in the middle can effectively improve the ion transport efficiency in the middle region of the electrode assembly 100, thereby improving the rate performance and charge / discharge response speed of the battery 1000.

[0088] In some embodiments, combined with Figure 5 It is understood that the end of the indentation 12c away from the thin coating area 12b extends to the edge of the thick coating area 12a. At this time, the indentation 12c penetrates the edge of the thick coating area 12a away from the thin coating area 12b, and the indentation 12c is directly connected to the outside of the diaphragm 10, which accelerates the electrolytic wetting speed.

[0089] In some embodiments, the end of the indentation 12c near the thin coating area 12b extends beyond the thick coating area 12a and into the adjacent thin coating area 12b. This design avoids the indentation 12c from abruptly terminating at the boundary between the thick coating area 12a and the thin coating area 12b, thus preventing structural breaks. It allows for a more continuous and smooth transmission of stress from the edge thick coating area 12a to the thin coating area 12b, reducing crack formation and resulting in a tighter bond between the thick coating area 12a and the thin coating area 12b, thereby improving the overall structural continuity of the coating 12 of the diaphragm 10.

[0090] In some embodiments, combined with Figure 4 Understand that the indentation 12c has a continuously arranged groove structure, and the bottom wall surface of the indentation 12c near the thin coating area 12b is flush with or lower than the surface of the thin coating area 12b.

[0091] The dent 12c has a continuously arranged groove structure, which provides an unobstructed and rapid wetting channel for the electrolyte, significantly improving the electrolyte wetting effect.

[0092] The end of the indentation 12c closest to the thin coating area 12b is the inner end. Since the bottom wall surface of the inner end of the indentation 12c is flush with the surface of the thin coating area 12b, or the bottom wall surface of the inner end of the indentation 12c is lower than the surface of the thin coating area 12b, the electrolyte can quickly and unobstructedly penetrate into the central area of ​​the electrode assembly 100 along the continuous groove, which greatly shortens the liquid injection time and improves production efficiency.

[0093] In some embodiments, the indentation 12c is an indentation. In this case, a high-rigidity microstructure reinforcing rib is formed locally at the edge of the diaphragm 10, which can actively support the edge of the diaphragm 10 and reduce the problem of edge folding of the diaphragm 10.

[0094] Furthermore, combined Figure 4 It is understood that the indentation 12c extends continuously in an arch shape, and all the indentations 12c arch in the same direction as the first extension end D1 of the diaphragm 10.

[0095] Understandably, the indentation 12c is a continuous, smooth, arched shape. The direction of the arch refers to the orientation of the apex of the arc-shaped cross-section.

[0096] In practical applications, when the electrode assembly 100 is wound to form the diaphragm 10, the first extension end D1 is located at its winding tail end, and all the indentations 12c are arched away from the first extension end D1. That is, during the battery winding process of the separator 10, each indentation 12c arches towards the winding start end along the winding feed direction. It can effectively generate a reaction force to resist the folding of the edge of the diaphragm 10, which is conducive to stress release and inhibits folding during the winding process.

[0097] It is worth noting that when the electrode assembly 100 has a wound structure, the inner winding has the smallest radius of curvature, the material bending stress is the largest, and the accumulated radial pressure between layers has not yet formed a uniform distribution. Therefore, the edge of the diaphragm 10 is very prone to instability and folding inward. The arched direction of the indentation 12c is towards the beginning of the winding. In the early stage of winding, when the edge of the diaphragm 10 tries to fold inward under bending stress and radial compression, the arc-shaped micro-reinforcing ribs formed by the indentation 12c provide geometric interference and rigid support first, thereby "actively resisting" the folding path of the edge of the diaphragm 10 and resisting the tendency of the diaphragm 10 to fold inward.

[0098] In another embodiment, the indentation 12c extends continuously in a straight strip shape. Specifically, the indentation 12c can extend linearly along the width direction X of the substrate 11, or it can extend obliquely relative to the width direction X of the substrate 11. In this case, the indentation 12c has a simple structure and is easy to form.

[0099] In another embodiment, the indentation 12c includes a plurality of indentations intermittently arranged along its extension direction Y. In this case, the indentation 12c is formed by the plurality of indentations arranged according to a predetermined extension path, which can be a straight line, a curve, a square line, etc. This extension path is located in the extension direction Y of the indentation 12c.

[0100] The concave 12c structure helps maintain the structural continuity of the coating 12 of the diaphragm 10 and effectively constrains the edge deformation of the diaphragm 10.

[0101] In another embodiment, the projection of the indentation 12c along the thickness direction Z is polygonal or crescent-shaped.

[0102] Specifically, the projection of the indentation 12c can be a square, trapezoid, or other polygon. The edges and straight sides of the polygonal indentation 12c can provide stronger mechanical support, which is equivalent to setting a "rigid reinforcing rib" at the edge of the diaphragm 10, significantly improving the resistance to folding and tearing.

[0103] When the projection of indentation 12c is crescent-shaped (in combination with...) Figure 4 (Understanding), its curved wall surface avoids stress concentration caused by sharp edges, which can significantly reduce the generation of cracks. Moreover, the crescent-shaped structure can conform to the winding curvature during winding, guiding the diaphragm 10 to deform in a preset direction, reducing the folding and wrinkling of the diaphragm 10 edges.

[0104] In one specific embodiment of this application, the diaphragm 10 includes a coating 12 and a substrate 11. Along the width direction X of the substrate 11, the coating 12 includes a thin coating area 12b and a thick coating area 12a, with the thick coating areas 12a arranged on both sides of the thin coating area 12b. Each thick coating area 12a has a plurality of indentations 12c, which extend in a crescent shape and penetrate both ends of the thick coating area 12a along the width direction X of the substrate 11.

[0105] Figure 6 This is a schematic diagram of the structure of a wound electrode assembly 100 according to some embodiments. Figure 7 This is a schematic diagram of the structure of a stacked electrode assembly 100 according to some embodiments.

[0106] The electrode assembly 100 in this application is described in detail below.

[0107] Please refer to Figure 6 and Figure 7 Understandably, the electrode assembly 100 in this application embodiment includes a positive electrode 20, a negative electrode 30, and at least one diaphragm 10 as described in the above embodiment, the diaphragm 10 being separated between the positive electrode 20 and the negative electrode 30.

[0108] The electrode assembly 100 has a coating 12 on the separator 10 that enhances the adhesion between the separator 10 and the positive electrode 20 / negative electrode 30. The thin coating area 12b and the indentation 12c design also increase the gap between the separator 10 and the electrode, providing a channel for electrolyte wetting, accelerating the electrolyte wetting efficiency, increasing the electrolyte storage capacity, and thus improving the cycle life of the battery 1000.

[0109] In some embodiments, combined with Figure 6It is understood that the electrode assembly 100 has a wound structure. The gap of the indentation 12c in the thick coating area 12a of each diaphragm 10 increases in a gradient along the winding direction of the diaphragm 10, and the first extension end D1 of the diaphragm 10 is located at its winding tail end.

[0110] As mentioned above, for the wound electrode assembly 100, the inner ring is more difficult to wet with electrolyte than the outer ring. In this case, the indentation spacing J of each thick coating area 12a is gradually increased towards the first extension end D1, so that the indentations 12c of the diaphragm 10 located in the inner ring of the electrode assembly 100 are more densely distributed than the indentations 12c of the diaphragm 10 located in the outer ring of the electrode assembly 100. This provides more channels for the electrolyte to wet the inner ring of the electrode assembly 100, thereby improving the wetting effect of the inner ring of the electrode assembly 100.

[0111] Understandably, the wound electrode assembly 100 typically includes two diaphragms 10, and the spacing of the indentations 12c on each diaphragm 10 is arranged independently according to the above-described pattern.

[0112] Specifically, in the embodiments, combined with Figure 6 Understand that each diaphragm 10 is wound to form multiple turns of the first isolation section G1. In every two adjacent turns of the first isolation section G1, the indentation spacing J of the first isolation section G1 located in the inner turn is smaller than the indentation spacing J of the first isolation section G1 located in the outer turn.

[0113] Understandably, the wound electrode assembly 100 includes a flat region Q1 and a first bending region Q2 and a second bending region Q2 located on both sides of the flat region Q1. The winding method of the electrode assembly 100 is typically as follows: first, a predetermined length of the diaphragm 10 is clamped onto a winding needle; then, the winding needle is rotated to insert the positive electrode 20 and the negative electrode 30 according to predetermined requirements, and then the assembly is wound into a wound piece; then, the winding needle is removed, and the wound piece is pressed down to obtain the wound electrode assembly 100. The first turn, the first isolation segment G1, may include the diaphragm 10 within the predetermined length (located in the flat region Q1), and terminates when the diaphragm 10 bends and passes through the first bending region Q2 and the second bending region Q2 once. The range of the subsequent turns of the first isolation segment G1 is determined from the termination position of the previous turn of the first isolation segment G1 until it passes through the first bending region Q2 and the second bending region Q2 once.

[0114] The larger the indentation spacing J of the first isolation section G1, the sparser the distribution of indentations 12c, and the fewer the number of indentations 12c, resulting in a weaker effect on improving electrolyte wetting. Generally, the indentations 12c are evenly spaced within each turn of the first isolation section G1, and the indentation spacing J between any two adjacent first isolation sections G1 gradually increases from the beginning to the end of the winding. The number of indentations 12c in the outer first isolation section G1 is less than the number of indentations 12c in the inner first isolation section G1.

[0115] At this point, by using each first isolation segment G1 as an arrangement unit to change the indentation spacing J in a stepped manner, not only can the electrolyte wetting period be accurately matched, but the processing difficulty can also be reduced.

[0116] In a further embodiment, the indentation spacing J of the first isolation segment G1 in each ring is the first spacing J1, which increases linearly with the increase of m, where d1 ranges, d2 ranges, and m is the number of rings in which the first isolation segment G1 is located, 10≤m≤100.

[0117] That is, the indentation spacing J of the first isolation segment G1 from the 10th to the 100th ring increases linearly with the number of layers it belongs to, so that the indentation spacing J of the first isolation segment G1 in each ring has an increasing gradient distribution.

[0118] The limitation of 10 ≤ m ≤ 100 is mainly due to the fact that, in some cases, the winding process of the wound electrode assembly 100 requires fixing the first end of the separator 10 to the winding needle, with the first few turns tightly wound around the surface of the winding needle. The main function is to fix the starting point of the winding, rather than to effectively isolate the separator. This separator 10 is not attached to the electrode sheet, so there is no need to consider the electrolyte wetting effect. Secondly, this separator 10 has a small bending radius. If the indentation spacing J is designed according to the formula, it will result in the indentation spacing J being too small. When the separator 10 is bent, stress will concentrate at the indentation 12c, which is prone to cracking or breakage. In order to take into account more application scenarios, the above formula is applied to determine the indentation spacing J on the first isolation section G1 where the number of turns m is not less than 10.

[0119] In addition, in some cases, the electrode assembly 100 is wrapped with several extra layers of separator 10, and adhesive tape is used to bind the electrode assembly 100 to prevent loosening. Moreover, the outer separator 10 is in the performance saturation zone, and the gap between the outer few layers of separator 10 and the electrode is often relatively large. Therefore, a recessed 12c structure is not required to ensure good electrolyte wetting, otherwise, it would result in structural redundancy. For power batteries 1000, the number of separator 10 layers is usually relatively large (usually not exceeding 100 or with little margin exceeding 100). Applying the above formula to the first isolation section G1, where the number of layers m does not exceed 100, can accommodate most battery 1000 types and reduce structural redundancy.

[0120] In some embodiments, each diaphragm 10 is wound to form multiple turns of first isolation segment G1. The multiple turns of first isolation segment G1 are divided into multiple isolation groups from the inside to the outside. Each isolation group includes multiple turns of first isolation segment G1 arranged adjacently. The indentation spacing J of the first isolation segment G1 in the same group is equal, and the indentation spacing J of different isolation groups increases sequentially from the inside to the outside.

[0121] For example, in the first 1 to n cycles, the number of indentations 12c in each layer of the first isolation segment G1 is equal, which is 10-20; 1≤n≤20; in the n to p cycles, the number of indentations 12c in each layer of the first isolation segment G1 is equal, which is 10-15; 21≤p≤50; in the p to q cycles, the number of indentations 12c in each layer of the first isolation segment G1 is equal, which is 8-10; 51≤p≤80; in the q to m cycles, the number of indentations 12c in each layer of the first isolation segment G1 is equal, which is 5-8; 81≤p≤100.

[0122] At this time, the number of dents 12c in the first isolation section G1 of the same group remains consistent. During the processing, the same rolling parameters can be set for the group, without the need to adjust the equipment parameters round by round, which reduces the processing complexity and error rate, effectively improves production efficiency, and reduces manufacturing costs.

[0123] In some embodiments, combined with Figure 6 It is understood that the electrode assembly 100 includes a flat region Q1 and a bent region Q2, with bent regions Q2 provided on both sides of the flat region Q1, and the indentation 12c located in the flat region Q1.

[0124] In the winding process, the bending zone Q2 is the core area of ​​stress concentration. If the indentation 12c is set in the bending zone Q2, it will further weaken the strength of the bending zone Q2, limit the bending ability of the bending zone Q2, and increase the risk of failure such as cracks and fractures.

[0125] The flat region Q1 is the main contact area between the electrode and the separator 10. Arranging the indentation 12c in the flat region Q1 can more effectively guide the electrolyte flow, ensure that the active material is fully wetted, and improve the electrochemical performance.

[0126] In some embodiments, combined with Figure 7 It is understood that the electrode assembly 100 has a stacked structure, and the indentation spacing J of each diaphragm 10 shows a trend of first decreasing and then increasing along the stacking direction of the electrode assembly 100.

[0127] The stacked electrode assembly 100 is typically formed by folding a diaphragm 10 in a Z-shape along the stacking direction, with the positive electrode 20 and negative electrode 30 alternately placed in the arrangement space formed between adjacent diaphragms 10.

[0128] For the stacked electrode assembly 100, in the stacking direction, the central region is more difficult to be wetted by electrolyte than the two end edges. At this time, the indentation spacing J on the diaphragm 10 first decreases and then increases along the stacking direction, making the indentations 12c of the diaphragm 10 in the central region of the electrode assembly 100 more densely distributed than the indentations 12c of the diaphragm 10 in the end regions of the electrode assembly 100. This provides more channels for electrolyte to wet the central region of the electrode assembly 100, thereby improving the wetting effect in the central region of the electrode assembly 100.

[0129] In some embodiments, each diaphragm 10 includes multiple layers of second isolation segments G2 disposed along the stacking direction. The indentation spacing J of each layer of second isolation segment G2 is a second spacing J2. J2 changes with the increase of n, first decreasing and then increasing. n is the number of layers where the second isolation segment G2 is located, and 10≤n≤100.

[0130] At this point, J2 first decreases and then increases with the increase of the number of layers containing the second isolation section G2, which matches the structural characteristics of the stacked electrode assembly 100 and can improve the electrolyte wetting effect in the middle region of the electrode assembly 100. Specifically, J2 can be determined according to the quadratic function J2 = d3 + d4*n + d5*n^2, where d3, d4, and d5 are all positive numbers. Their respective value ranges can be flexibly adjusted according to actual scenarios such as the number of stacked layers, the material and thickness of the separator 10, and the type of battery 1000, to precisely adapt to different specifications of the stacked electrode assembly 100. This is not limited here.

[0131] In the bottom first few layers and top last few layers of the stacked electrode assembly 100, the electrolyte wetting path is very short, and the wetting effect can be achieved without setting the indentation 12c. Moreover, in some cases, the first few layers of the second diaphragm 10 segments or the last few layers of the second diaphragm 10 segments may be folded together without clamping the electrode to stabilize the two ends of the electrode assembly 100, thus avoiding the problem of difficult electrolyte wetting. In this case, the indentation 12c can be omitted or the indentation 12c gap can be set according to a fixed value. In addition, the number of stacked layers of the electrode assembly 100 usually does not exceed this. In order to take into account more application scenarios, reduce costs, and reduce structural redundancy, the above formula is applied to determine the indentation spacing J on the second isolation segment G2 where the number of layers n is not less than 10 and does not exceed 100.

[0132] Figure 8 This is a schematic diagram of the stacking of the separator 10 and the negative electrode 30 in some embodiments.

[0133] In some embodiments, combined with Figure 8 It is understood that the negative electrode 30 is positioned on both sides of the separator 10 in the width direction X, corresponding to the thick coating area 12a on the separator 10.

[0134] The edges of the negative electrode 30 are prone to burrs and lithium plating. The thick coating area 12a can provide higher insulation strength and mechanical straightness. Covering the edges of the negative electrode 30 with it can effectively prevent edge burrs from piercing the separator 10 and avoid short circuits.

[0135] Because the edge of the negative electrode 30 has high reactivity and high ion transport requirements, it is set in the corresponding thick coating area 12a. The concave structure 12c can significantly increase the wetting efficiency of the electrolyte on the edge area of ​​the negative electrode 30, improve the ion conduction capacity of the edge area of ​​the negative electrode 30, enhance the utilization rate of the active material at the edge of the negative electrode 30, and improve the energy density and power performance of the battery 1000.

[0136] In some embodiments, combined with Figure 8 It is understood that all the indentations 12c in the thick coating area 12a are arched in the same direction, and the edge of the negative electrode 30 overlaps with the arch point of the indentation 12c.

[0137] That is, the edge of the negative electrode 30 is aligned with the arched point of the indentation 12c. Aligning the edge of the negative electrode 30 with the arched point of the indentation 12c is equivalent to forming a row of flow guides at the edge of the negative electrode 30, which can guide the electrolyte to flow in a directional direction along the arched direction of the indentation 12c to the edge area of ​​the negative electrode 30, significantly improving the wetting efficiency of the electrolyte at the edge of the negative electrode 30.

[0138] Figure 9 This is a schematic flowchart of a method for producing the diaphragm 10 according to some embodiments.

[0139] The following describes the production method of the diaphragm 10 in this application.

[0140] Please refer to Figure 9 The method for producing the diaphragm 10 in this application embodiment includes: S1. Provide a blank P, which is divided into a thick coating area 12a and a thin coating area 12b along its width direction X. The thick coating area 12a is located at the edge of the blank P, and the thick coating area 12a is arranged on both sides of the thin coating area 12b. The thin coating area 12b is recessed relative to the thick coating area 12a. S2. Unwind the blank P and use rollers 2310 to press multiple indentations 12c on each thick coating area 12a at intervals. The indentations 12c extend from one end of the thick coating area 12a in the width direction X to the other end to obtain the diaphragm 10.

[0141] S1 and S2 can be performed simultaneously. At this time, the formation of the blank P can be performed simultaneously with the roller 2310 pressing the indentation 12c. The specific process is as follows: the substrate 11 is unwound. During the conveyor belt process of the substrate 11, the coating device (not shown) is first used to form a coating 12 with a thick coating area 12a and a thin coating area 12b on the substrate 11. Then, the roller 2310 is used to press the indentation 12c on the thick coating area 12a. It is worth noting that before calling roller 2310, other roller pressing devices can be used for pre-rolling to pre-compact the coating 12, eliminating most of the air bubbles and voids inside the coating 12, providing a relatively dense and uniform base for the subsequent forming of the indentation 12c, and avoiding the coating from being over-fed, resulting in irregular deformation or cracking. Alternatively, before calling roller 2310, a drying device can be used for pre-drying, so that the coating 12 is in a semi-dry state. In this state, the coating 12 material has suitable viscoelasticity and plasticity, and can generate dense plastic flow under the action of roller pressing, forming a crack-free and structurally solid indentation 12c.

[0142] S1 and S2 can be performed sequentially. For example, first, a blank P with a thin coating area 12b and a thick coating area 12a of suitable viscoelasticity and plasticity is coated on both sides of the substrate 11, and the blank P is then wound up. Then, the blank P is unwound, and during the unwinding process, the rollers 2310 simultaneously press indentations 12c into the thick coating area 12a of the coating 12 on both sides of the substrate 11 to obtain the diaphragm 10.

[0143] At this time, the thick coating area 12a is pressed by roller 2310 to form a dent 12c (dent 12c is an indentation). By compacting the dent 12c area, the reliability of the thick coating area 12a structure is improved and the risk of edge flipping and cracking of the diaphragm 10 is reduced.

[0144] In some embodiments, the unwound blank P includes: The conveyor speed V1 of the billet P and the linear speed V2 of the roller 2310 are adjusted according to preset rules; wherein, the preset rules include one of the following conditions: controlling k to increase continuously, controlling k to increase intermittently, and controlling k to decrease first and then increase, k=V1:V2.

[0145] Understandably, the outer periphery of the roller 2310 is provided with a rolling portion 2312 for forming the indentation 12c. The linear velocity V2 of the roller 2310 refers to the length that the roller 2310 rotates per unit time. The rotational speed of the roller 2310 is defined as r (rpm), and the diameter of the roller 2310 is defined as D. V2 = πrD ÷ 60, and the magnitude of V2 is changed by changing r.

[0146] N roller pressing sections 2312 are set on the roller 2310. The roller 2310 completes N roller pressings on the blank P for each rotation. The interval time of each roller pressing is t=πD / (V2*N). The indentation spacing is J=V1*t=V1*πD / (V2*N). Substituting k, we get the indentation spacing J=k*πD / N.

[0147] When k increases continuously, the indentation spacing J increases continuously, resulting in a diaphragm 10 with a gradually increasing indentation spacing J. When k increases intermittently, for example, by adjusting the size of k at regular intervals, a diaphragm 10 with a stepped increase in indentation spacing J is obtained, resulting in a wound electrode assembly 100 where the indentation spacing J is equal on each first isolation segment G1, but unequal indentation spacing J on different first isolation segments G1. When k first decreases and then increases, the indentation spacing J first decreases and then increases, resulting in a diaphragm 10 where the indentation spacing J first decreases and then increases, resulting in a stacked electrode assembly 100 where the indentation spacing J of the second isolation segment G2 decreases from both ends to the middle.

[0148] At this point, adjusting the value of k according to the set rules to adjust the indentation spacing J simplifies the control logic.

[0149] It is worth noting that after obtaining the separator 10 in S2, the separator 10 can be wound up, or the obtained separator 10 can be directly integrated with the winding process or the stacking process, saving the winding step of the separator 10 and improving the battery production efficiency.

[0150] The diaphragm production equipment 2000 described in this application is described below.

[0151] Figure 10 This is a schematic diagram of the composition of a diaphragm production apparatus 2000 according to some embodiments.

[0152] Please refer to Figure 10 The diaphragm production equipment 2000 in this embodiment includes an unwinding mechanism 2100, a winding mechanism 2200, and a roller mechanism 2300. The roller mechanism 2300 includes sets of rollers 2310, each set including a pair of oppositely arranged rollers 2310. The paired rollers 2310 are spaced apart to form a belt-carrying gap. Each roller 2310 has a pressing portion 2312 for forming indentations 12c, extending axially from one end of the roller 2310 to the other. The diaphragm production equipment 2000 can perform the diaphragm 10 production method described in the above embodiment.

[0153] Two pairs of rollers 2310 are provided with the same number of rolling sections 2312, and both rollers rotate at the same speed. The two rollers 2310 in each group of rollers 2310 are used to simultaneously roll the thick coating area 12a on the same edge of both sides of the substrate 11. One group of rollers 2310 is provided for the thick coating area 12a on each side edge of the substrate 11.

[0154] The shape of the roller pressing part 2312 matches the shape of the indentation 12c. If the indentation 12c is arched, the roller pressing part 2312 is an arched shape that arches to one side. If the indentation 12c is straight, the roller pressing part 2312 is straight.

[0155] Figure 11 This is a schematic diagram of the roller 2310 assembly in some embodiments.

[0156] In some embodiments, combined with Figure 11 It is understood that the roller 2310 includes a base 2311 and a rolling section 2312. The rolling section 2312 is disposed on the base 2311, and multiple rolling sections 2312 are arranged at intervals along the rotation direction of the roller 2310. The base 2311 is connected to a drive mechanism to realize the rotation of the roller 2310 around a central axis. The rolling section 2312 is usually integrally connected to the base 2311. Providing multiple rolling sections 2312 on the roller 2310 can improve the preparation efficiency of the indentation 12c and accelerate the production of the diaphragm 10.

[0157] With the same indentation spacing J and maintaining the same v1, t is fixed. The fewer the number of roller pressing sections 2312, the larger the diameter D of the roller 2310 needs to be at the same roller rotation speed. An excessively large diameter D results in the roller 2310 occupying too much space, which is detrimental to equipment installation and cost control. The roller 2310 should be kept within a reasonable size range to facilitate installation and reduce costs.

[0158] In some embodiments, the roll forming portion 2312 extends continuously and is arched in its plane of rotation.

[0159] The roller pressing section 2312 is designed with an arched structure so that the indentation 12c is arched. The arching direction is located in the rotation plane of the roller pressing section 2312. In one embodiment, the roller pressing section 2312 arches along the rotation direction of the roller 2310. Thus, when the forming process of the diaphragm 10 is carried out simultaneously with the winding process or when the diaphragm 10 is produced separately and then wound up, since the rotation direction of the roller pressing section 2312 is consistent with the feed direction of the blank P, when the arching direction is consistent with the rotation direction, the indentation 12c obtained on the diaphragm 10 arches towards the winding start end. When the diaphragm 10 is wound up or rolled up, the arched indentation 12c can actively support the edge of the diaphragm 10, prevent the edge of the diaphragm 10 from folding over, and reduce the risk of folding over when the diaphragm 10 is wound up or rolled up. Of course, in other embodiments, the roller pressing section 2312 arches away from the rotation direction of the roller 2310. In this case, the diaphragm 10 obtained in step S2 is first wound up and then unwound to participate in the winding process, so that the arching direction of the indentation 12c is towards the winding start end during winding.

[0160] Specifically, the roller pressing section 2312 can be crescent-shaped. The crescent-shaped arched wall avoids stress concentration caused by sharp edges and corners, which can significantly reduce the generation of cracks in the diaphragm 10.

[0161] In some embodiments, along the axial direction of the roller 2310, the projection of the outer contour of the base 2311 falls within the area of ​​the equivalent cylinder coaxial with the base 2311. The base 2311 can be cylindrical or other non-cylindrical structures, as long as each roller pressing portion 2312 is located on the equivalent cylinder of the base 2311. When the base 2311 is a non-cylindrical structure, its volume can be reduced, thus lowering costs.

[0162] The equivalent cylinder of the base 2311 refers to a virtual cylinder that is equivalent to the diameter D of the roller 2310.

[0163] Figure 12 This is a schematic diagram of the operation of the roller mechanism 2300 in some embodiments.

[0164] In some embodiments, combined with Figure 12It is understood that the roller mechanism 2300 includes an adjustment assembly 2320, on which rollers 2310 are mounted. The adjustment assembly 2320 is used to adjust the size of the belt travel gap between the pair of rollers 2310.

[0165] The gap between the paired rollers 2310 determines the depth of the dent 12c. In practical applications, the belt clearance of the rollers 2310 can be adjusted by adjusting the component 2320 to meet the processing requirements of different dent depths 12c, thus expanding the application scenarios of the equipment.

[0166] The adjustment component 2320 can be conventionally designed by those skilled in the art to adjust the position of the radial adjustment roller 2310 along the direction perpendicular to the isolation belt. For example, the adjustment component 2320 can be a cylinder.

[0167] The battery 1000 in this application embodiment includes the electrode assembly 100 in the above embodiment.

[0168] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0169] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A diaphragm (10), characterized in that, include: Substrate (11), extending longitudinally; The coating (12) extends in the same direction as the substrate (11) and is applied to at least one side surface of the substrate (11) in the thickness direction (Z). The coating (12) is divided into a thick coating area (12a) and a thin coating area (12b) along the width direction (X) of the substrate (11). The thick coating area (12a) is arranged on both sides of the thin coating area (12b), and the thin coating area (12b) is recessed relative to the thick coating area (12a). Each of the thick coating areas (12a) is provided with a plurality of indentations (12c), which are spaced apart along the extension direction (Y) of the diaphragm (10), and each indentation (12c) extends from one end of the thick coating area (12a) in the width direction (X) to the other end.

2. The diaphragm (10) according to claim 1, characterized in that, The diaphragm (10) has a first extended end (D1), and the interval between adjacent indentations (12c) is the indentation spacing (J); The indentation spacing (J) of each thick coating area (12a) increases gradually along the extension direction (Y) of the diaphragm (10) toward the first extension end (D1); or the indentation spacing (J) of each thick coating area (12a) decreases first and then increases along the extension direction (Y) of the diaphragm (10) toward the first extension end (D1).

3. The diaphragm (10) according to claim 1, characterized in that, The indentation spacing (J) of each of the thick-coated areas (12a) varies sequentially along the extension direction (Y) of the diaphragm (10) toward the first extension end (D1) of the diaphragm (10) according to an increasing rule or a rule of first decreasing and then increasing; or, The diaphragm (10) is divided into multiple isolation segments (G) along its extension direction (Y). The indentation spacing (J) of each isolation segment (G) is equal. The indentation spacing (J) of adjacent isolation segments (G) changes gradually along the extension direction (Y) of the diaphragm (10) toward the first extension end (D1) of the diaphragm (10) in an increasing manner or a manner that first decreases and then increases.

4. The diaphragm (10) according to claim 1, characterized in that, The maximum thickness of the thick coating area (12a) is a, the width of the thick coating area (12a) is c, the depth of the indentation (12c) is T, the length of the indentation (12c) is L, the minimum thickness of the thin coating area (12b) is b, and the diaphragm (10) satisfies at least one of the following conditions: T is negatively correlated with L; a≥T≥b; L≥c; 20mm < c < 80mm; 1μm≤a≤10μm; 0.5μm≤b≤3μm; 20mm≤L≤80mm.

5. The diaphragm (10) according to claim 1, characterized in that, The thick coating areas (12a) located on both sides of the diaphragm (10) are the first thick coating area (a1) and the second thick coating area (a2), respectively. Wherein, the depth of the indentation (12c) in both the first thick coating area (a1) and the second thick coating area (a2) decreases gradually along the width direction (X) of the substrate (11) toward the side where the adjacent thin coating area (12b) is located; and / or, The distribution density of the indentations (12c) in the first thick coating area (a1) is greater than the distribution density of the indentations (12c) in the second thick coating area (a2); and / or, The length of the indentation (12c) in the first thick coating area (a1) is greater than the length of the indentation (12c) in the second thick coating area (a2); and / or, The thickness of both the first thick coating area (a1) and the second thick coating area (a2) decreases from the edge of the diaphragm (10) towards the adjacent thin coating area (12b); and / or, The thickness of the thin coating area (12b) gradually decreases from both ends to the middle along the width direction (X), and the thin coating area (12b) and the thick coating areas (12a) on both sides are set with the same thickness at the boundary position.

6. The diaphragm (10) according to claim 1, characterized in that, The indentation (12c) extends from the thin-coated area (12b) to the edge of the thick-coated area (12a), or the indentation (12c) extends beyond the thick-coated area (12a) into the adjacent thin-coated area (12b); and / or, The indentation (12c) is a continuously arranged groove structure, and the bottom wall of the indentation (12c) near the thin coating area (12b) is flush with or lower than the surface of the thin coating area (12b).

7. The diaphragm (10) according to any one of claims 1 to 6, characterized in that, The indentation (12c) is an indentation, and the indentation (12c) extends continuously in an arch shape, with all the indentations (12c) arching in the same direction away from the first extension end (D1) of the diaphragm (10); or, The indentation (12c) extends continuously into a straight strip; or, The indentation (12c) comprises a plurality of indentations arranged intermittently along its extension direction; or, The projection of the indentation (12c) along the thickness direction (Z) is polygonal or crescent-shaped.

8. An electrode assembly (100), characterized in that, include: A positive electrode (20), a negative electrode (30), and at least one separator (10) as described in any one of claims 1 to 7, the separator (10) being separated between the positive electrode (20) and the negative electrode (30).

9. The electrode assembly (100) according to claim 8, characterized in that, The electrode assembly (100) has a wound structure. The gap of the indentation (12c) in the thick coating area (12a) of each diaphragm (10) increases in a gradient along the winding direction of the diaphragm (10). The first extension end (D1) of the diaphragm (10) is located at its winding tail end.

10. The electrode assembly (100) according to claim 9, characterized in that, Each of the diaphragms (10) is wound to form multiple turns of the first isolation section (G1). In every two adjacent turns of the first isolation section (G1), the indentation spacing (J) of the first isolation section (G1) located on the inner turn is smaller than the indentation spacing (J) of the first isolation section (G1) located on the outer turn.

11. The electrode assembly (100) according to claim 10, characterized in that, The indentation spacing (J) of the first isolation segment (G1) in each lap is the first spacing J1. J1 increases linearly with the increase of m, where m is the number of laps in which the first isolation segment (G1) is located, and 10≤m≤100.

12. The electrode assembly (100) according to claim 9, characterized in that, Each of the diaphragms (10) is wound to form multiple turns of the first isolation section (G1), which is divided into multiple isolation groups from the inside to the outside. Each isolation group includes multiple turns of the first isolation section (G1) arranged adjacently. The indentation spacing (J) of the first isolation segment (G1) in the same group is equal, and the indentation spacing (J) of different isolation groups increases sequentially from the inside to the outside.

13. The electrode assembly (100) according to claim 9, characterized in that, The electrode assembly (100) includes a straight area (Q1) and a bent area (Q2), with the bent area (Q2) provided on both sides of the straight area (Q1), and the indentation (12c) located in the straight area (Q1).

14. The electrode assembly (100) according to claim 8, characterized in that, The electrode assembly (100) has a stacked structure, and the indentation spacing (J) of each diaphragm (10) shows a trend of first decreasing and then increasing along the stacking direction of the electrode assembly (100).

15. The electrode assembly (100) according to claim 14, characterized in that... , Each of the diaphragms (10) includes multiple layers of second isolation sections (G2) arranged along the stacking direction. The indentation spacing (J) of each layer of the second isolation section (G2) is the second spacing J2. J2 changes with the increase of n, first decreasing and then increasing. n is the number of layers where the second isolation section (G2) is located, 10≤n≤100.

16. The electrode assembly (100) according to claim 8, characterized in that, The negative electrode sheet (30) is disposed on both sides of the separator (10) in the width direction (X) corresponding to the thick coating area (12a) on the separator (10); and / or, All the indentations (12c) in the thick coating area (12a) are arched in the same direction, and the edge of the negative electrode (30) overlaps with the arch point of the indentation (12c).

17. A method for producing a diaphragm, characterized in that, include: A blank (P) is provided, which is divided into a thick coating area (12a) and a thin coating area (12b) along its width direction (X). The thick coating area (12a) is located at the edge of the blank (P), and the thick coating area (12a) is arranged on both sides of the thin coating area (12b). The thin coating area (12b) is recessed relative to the thick coating area (12a). The blank (P) is unwound, and a roller (2310) is used to press a plurality of indentations (12c) at intervals on each of the thick coating areas (12a). The indentations (12c) extend from one end of the thick coating area (12a) in the width direction (X) to the other end to obtain a diaphragm (10).

18. The diaphragm production method according to claim 17, characterized in that, The unwound billet (P) comprises: The conveyor speed V1 of the blank (P) and the linear speed V2 of the roller (2310) are adjusted according to preset rules; wherein, the preset rules include one of the following conditions: controlling k to increase continuously, controlling k to increase intermittently, and controlling k to decrease first and then increase, k=V1:V2.

19. A diaphragm production equipment (2000), characterized in that, include: The unwinding mechanism (2100), the winding mechanism (2200), and the roller mechanism (2300) include roller groups, each roller group including a pair of rollers (2310) arranged opposite to each other, the two rollers (2310) being spaced apart to form a belt carrying gap, the rollers (2310) being provided with a pressing portion (2312) for forming a groove (12c), the pressing portion (2312) extending from one end of the roller (2310) in the axial direction to the other end; The diaphragm production equipment (2000) is capable of performing the diaphragm production method as described in any one of claims 17 to 18.

20. The diaphragm production equipment (2000) according to claim 19, characterized in that, The roller (2310) includes a base (2311) and a rolling part (2312), wherein the rolling part (2312) is disposed on the base (2311); The roller pressing section (2312) is arranged in a plurality of portions at intervals along the rotation direction of the roller (2310); and / or, The roller pressing section (2312) extends continuously and is arched in its plane of rotation; and / or, Along the axial direction of the roller (2310), the projection of the outer contour of the base (2311) falls within the area of ​​an equivalent cylinder coaxial with the base (2311); and / or, The roller mechanism (2300) further includes an adjustment component (2320), on which the roller (2310) is mounted, and the adjustment component (2320) is used to adjust the size of the belt feed gap of the roller (2310).

21. A battery, characterized in that, Includes the electrode assembly (100) as described in claims 8 to 16.

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