Arc-shaped battery

Abstract

The invention provides an arc-shaped battery, the arc-shaped battery comprises a battery cell, the battery cell comprises a first side and a second side which are oppositely arranged along a first direction, and the second side of the battery cell bends towards the first side of the battery cell; the battery cell comprises a diaphragm and pole pieces, the pole pieces comprise a positive pole piece and a negative pole piece, the diaphragm comprises a plurality of diaphragm layers arranged along a first direction, and a single pole piece is clamped between two adjacent diaphragm layers; each diaphragm layer comprises first side edges which are oppositely arranged in the second direction, in the three adjacent diaphragm layers, the first side edge of the first diaphragm layer is adjacent to the first side edge of the second diaphragm layer, and the second side edge of the second diaphragm layer is adjacent to the second side edge of the third diaphragm layer; a notch is formed between every two adjacent first side edges, a notch is formed between every two adjacent second side edges, and the notches extend in the third direction. The diaphragm of the arc-shaped battery is not easy to wrinkle and accumulate.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a curved battery. Background Art

[0002] Curved batteries have been gradually applied to various wearable smart products, such as smart bracelets and VR glasses. By applying external force to the Z-stacked core, the flat core is deformed into a curved structure, which is then placed in a punched curved shell and injected with electrolyte to form a curved battery.

[0003] However, curved batteries may have the following problems: First, during the bending process of the Z-stacked core, the inner diaphragm is compressed and the outer diaphragm is stretched along the thickness direction of the core. The uneven stress distribution will cause wrinkles in certain areas of the diaphragm, thereby destroying the interface uniformity of the core, leading to lithium deposition, increased internal resistance, capacity decay and other problems in the core. Second, because the edge of the diaphragm must extend beyond the pole piece, after the Z-stacked curved battery is bent, the diaphragm will accumulate at the four corners of the core. On the one hand, the diaphragm accumulation forms a local thick area, which hinders the diffusion of heat inside the core, resulting in an increase in the temperature gradient. The accumulation area easily becomes a trigger point for thermal runaway. On the other hand, the accumulated diaphragm repeatedly rubs against the edge of the pole piece (such as under vibration conditions), which can easily accelerate diaphragm wear, causing microporous defects in the diaphragm, and thus lead to thermal runaway of the battery. Summary of the Invention

[0004] Based on this, the present application provides a curved battery to address the deficiencies in the related art.

[0005] The curved battery provided in the present application includes a battery cell, the battery cell including a first side and a second side arranged opposite to each other along a first direction, the second side of the battery cell being curved toward the first side of the battery cell;

[0006] The battery cell includes a diaphragm and pole pieces, the pole pieces include a positive pole piece and a negative pole piece, the diaphragm includes a plurality of diaphragm layers arranged along a first direction, and a single pole piece is sandwiched between two adjacent diaphragm layers;

[0007] Each diaphragm layer includes first sides opposite to each other along the second direction, and among three adjacent diaphragm layers, the first side of the first diaphragm layer is adjacent to the first side of the second diaphragm layer, and the second side of the second diaphragm layer is adjacent to the second side of the third diaphragm layer;

[0008] A cutout is provided between two adjacent first side edges and between two adjacent second side edges, and the cutout extends along the third direction;

[0009] The first direction is along the radial direction of the arc-shaped battery, one of the second direction and the third direction is along the axial direction of the arc-shaped battery, and the other is along the circumferential direction of the arc-shaped battery.

[0010] In a possible implementation, at least two cutouts are provided on both sides of the first side along the third direction, and / or at least two cutouts are provided on both sides of the second side along the third direction.

[0011] In a possible implementation, the at least two cutouts are symmetrically arranged relative to a center line of the diaphragm layer along the second direction.

[0012] In a possible implementation, a dimension h of a single incision along the third direction satisfies: 1 mm ≤ h ≤ 80 mm.

[0013] In a possible implementation, the arc length L of the battery cell and the dimension h of a single cutout along the third direction satisfy: 0.05≤h / L≤0.4;

[0014] And / or, the arc length L of the battery cell satisfies: 20 mm ≤ L ≤ 200 mm.

[0015] In a possible implementation, the bending radius R of the battery cell and the dimension h of a single cutout along the third direction satisfy: 0.003<h / R<1.3;

[0016] And / or, the bending radius R of the battery cell satisfies: 10mm≤R≤3600mm;

[0017] And / or, the central angle α of the battery cell satisfies: 3°<α<180°.

[0018] In a possible implementation, the size of the cutout of a single diaphragm layer along the second direction is W1;

[0019] A single diaphragm layer includes a main portion and an extended portion connected to each other, the extended portion being provided on at least one side of the main portion along the second direction, the projection of the negative electrode sheet on the diaphragm layer overlapping with the main portion, the projection of the negative electrode sheet on the diaphragm layer being staggered from the extended portion, the notch being provided in the extended portion, and the dimension of the extended portion along the second direction being W2;

[0020] W1 and W2 satisfy: 0.5*W2≤W1≤W2.

[0021] In one possible implementation, the negative electrode sheet includes a negative electrode active coating, which is disposed on at least one side of the negative electrode sheet in a thickness direction. The negative electrode active coating includes a silicon-based material, and a silicon content G of the negative electrode active coating and a dimension h of a single cutout along a third direction satisfy the following conditions: 2≤h / G≤1600.

[0022] And / or, the silicon content G of the negative electrode active coating satisfies: 5%≤G≤60%.

[0023] In one possible implementation, the negative electrode sheet further includes a negative electrode current collector, and the tensile strength TS of the negative electrode current collector along the circumference of the arc-shaped battery and the arc length L of the battery cell satisfy: 0.05≤L / TS≤0.2;

[0024] And / or, the circumferential extension rate EL of the arc-shaped battery of the negative electrode current collector and the arc length L of the battery cell satisfy: 250≤L / EL≤6670.

[0025] In one possible implementation, at least one convex portion is provided on one side surface of the positive electrode sheet, and a concave portion corresponding to the convex portion is provided on the other side surface of the positive electrode sheet, wherein the convex portion is convex toward the first side of the battery cell, and the concave portion is concave toward the first side of the battery cell;

[0026] The protrusion height PH of the protrusion satisfies: 3 μm≤PH≤30 μm.

[0027] The arc-shaped battery of the embodiment of the present application has three adjacent diaphragm layers, in which the first side of the first diaphragm layer is adjacent to the first side of the second diaphragm layer, and the second side of the second diaphragm layer is adjacent to the second side of the third diaphragm layer, so that the diaphragm can be continuously bent to form multiple diaphragm layers, thereby making the negative electrode sheet sandwiched between the first diaphragm layer and the second diaphragm layer able to be subjected to a greater restraining force, and making the positive electrode sheet sandwiched between the second diaphragm layer and the third diaphragm layer able to be subjected to a greater restraining force, thereby preventing relative movement between the negative electrode sheet and the diaphragm, and between the positive electrode sheet and the diaphragm, and effectively restraining the expansion of the battery cell.

[0028] Since there is a cutout between two adjacent first sides and a cutout between two adjacent second sides, when the battery cell is bent, the cutout can reduce the degree of coupling between adjacent diaphragm layers, thereby reducing the stress transfer path of the two adjacent diaphragm layers, and the cutout can effectively release the tensile stress or compressive stress of the diaphragm layer to prevent stress concentration in the diaphragm layer, thereby improving the phenomenon of diaphragm wrinkling, thereby improving the problems of lithium deposition and thermal runaway in curved batteries due to diaphragm wrinkling.

[0029] Since a cut is provided between two adjacent first sides and a cut is provided between two adjacent second sides, the diaphragm accumulation at the corners of the battery cell when the battery cell is bent can be effectively avoided, thereby preventing the diaphragm accumulation from affecting the heat dissipation at the corners of the battery cell, thereby preventing the formation of local over-temperature zones at the corners of the battery cell, and reducing micropore defects caused by diaphragm accumulation, thereby reducing the probability of thermal runaway of the arc battery, and improving the reliability of the battery cell packaging by reducing diaphragm accumulation.

[0030] Since there is a cutout between two adjacent first sides and a cutout between two adjacent second sides, after the battery cell is filled with electrolyte, the electrolyte can quickly enter the battery cell through the cutouts, thereby facilitating improved wettability of the electrolyte.

[0031] In addition to the technical problems solved by the embodiments of the present application described above, the technical features that constitute the technical solutions, and the beneficial effects brought about by the technical features of these technical solutions, other technical problems that can be solved by the curved battery provided by the present application, other technical features included in the technical solutions, and the beneficial effects brought about by these technical features will be further described in detail in the specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0033] Figure 1 A schematic diagram of the structure of a battery provided in an embodiment of the present application;

[0034] Figure 2 Another structural diagram of a battery provided in an embodiment of the present application

[0035] Figure 3 for Figure 2 Exploded diagram;

[0036] Figure 4 A schematic diagram of the structure of a battery cell in a battery provided in an embodiment of the present application;

[0037] Figure 5 This is another structural schematic diagram of a battery cell in a battery provided in an embodiment of the present application;

[0038] Figure 6 This is another structural schematic diagram of a battery cell in a battery provided in an embodiment of the present application;

[0039] Figure 7 for Figure 6 Schematic diagram of the structure of the middle diaphragm layer;

[0040] Figure 8 This is a schematic diagram of the structure of the battery separator when it is unfolded according to an embodiment of the present application;

[0041] Figure 9 This is another structural schematic diagram of the battery separator provided in an embodiment of the present application when it is unfolded;

[0042] Figure 10 for Figure 1 The main view;

[0043] Figure 11 This is a schematic diagram of the structure of the positive electrode sheet in the battery provided in an embodiment of the present application.

[0044] Description of reference numerals:

[0045] 100-battery cell; 110-diaphragm; 111-diaphragm layer; 1111-first side; 1112-second side; 1113-incision; 1114-main body; 1115-protruding portion; 120-pole sheet; 121-negative electrode sheet; 122-positive electrode sheet; 1221-convex portion; 1222-concave portion; 200-pole ear assembly; 210-negative electrode ear assembly; 211-negative electrode ear; 220-positive electrode ear assembly; 221-positive electrode ear. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below in conjunction with the drawings in the preferred embodiments of the present application. In the drawings, the same or similar reference numerals throughout represent the same or similar parts or parts with the same or similar functions. The described embodiments are part of the embodiments of the present application, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present application, and should not be understood as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The embodiments of the present application are described in detail below in conjunction with the drawings.

[0047] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to a fixed connection, an indirect connection via an intermediate medium, internal communication between two components, or an interaction between two components. Those skilled in the art will understand the specific meanings of these terms in this application based on specific circumstances.

[0048] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are orientations or positional relationships based on the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on this application.

[0049] The terms "first," "second," and "third" (if any) in the specification and claims of this application and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the application described herein can be implemented in orders other than those illustrated or described herein.

[0050] In addition, the terms "comprises" and "having" and any variations thereof are intended to cover a non-exclusive inclusion, for example, a process, method, system, product or display that includes a series of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, product or display.

[0051] The specific implementation of the arc-shaped battery provided in the embodiments of the present application is described in detail below with reference to the accompanying drawings.

[0052] In related technologies, curved batteries may have the following problems: First, when the Z-stacked core is bent, the inner diaphragm is compressed and the outer diaphragm is stretched along the thickness direction of the core. The uneven stress distribution will cause wrinkles in certain areas of the diaphragm, thereby destroying the interface uniformity of the core, resulting in problems such as lithium deposition and capacity attenuation in the core.

[0053] Secondly, since the edge of the diaphragm has to extend beyond the pole piece, after the Z-stacked curved battery is bent, diaphragm accumulation will appear at the four corners of the stacked core. On the one hand, the diaphragm accumulation forms a local thick area, which hinders the diffusion of heat inside the stacked core, resulting in an increase in the temperature gradient. The accumulation area easily becomes a trigger point for thermal runaway. On the other hand, the accumulated diaphragm repeatedly rubs against the edge of the pole piece (such as under vibration conditions), which easily accelerates the wear of the diaphragm, resulting in microporous defects such as damaged pore size uniformity, uneven porosity and closed-pore blockage in the diaphragm, which in turn leads to thermal runaway of the battery, capacity attenuation, etc., and the diaphragm accumulation will also affect the packaging reliability of the battery cell and the shell.

[0054] In view of the above problems, an embodiment of the present application provides a curved battery, which provides incisions on opposite sides of the diaphragm along the second direction so that the two adjacent diaphragm layers are partially continuous and partially disconnected, thereby reducing the degree of coupling between the diaphragm layers and providing stress release space for the diaphragm layers, thereby preventing the diaphragm from wrinkling and accumulation at the corners of the diaphragm, thereby improving the lithium plating problem, internal resistance increase problem, thermal runaway problem and capacity attenuation problem of the curved battery.

[0055] The specific implementation of the arc provided in this embodiment is described in detail below with reference to the accompanying drawings.

[0056] Reference Figures 1 to 9As shown, the arc-shaped battery provided in the embodiment of the present application includes a battery cell 100 , which includes a first side and a second side arranged opposite to each other along a first direction, and the second side of the battery cell 100 is bent toward the first side of the battery cell 100 .

[0057] The battery cell 100 includes a separator 110 and pole pieces 120 . The pole pieces 120 include a positive pole piece 122 and a negative pole piece 121 . The separator 110 includes a plurality of separator layers 111 arranged along a first direction. A single pole piece 120 is sandwiched between two adjacent separator layers 111 .

[0058] Each diaphragm layer 111 includes a first side 1111 and a second side 1112 disposed opposite each other along the second direction. Among three adjacent diaphragm layers 111, the first side 1111 of the first diaphragm layer 111 abuts the first side 1111 of the second diaphragm layer 111, and the second side 1112 of the second diaphragm layer 111 abuts the second side 1112 of the third diaphragm layer 111. A cutout 1113 is defined between two adjacent first sides 1111 and between two adjacent second sides 1112, extending along the third direction.

[0059] The first direction is along the radial direction of the arc-shaped battery, one of the second direction and the third direction is along the axial direction of the arc-shaped battery, and the other is along the circumferential direction of the arc-shaped battery. Figure 1 In the embodiment, the first direction is along the radial direction of the arc-shaped battery, the second direction is along the axial direction of the arc-shaped battery, and the third direction is along the circumferential direction of the arc-shaped battery. Figure 2 In the embodiment, the first direction is along the radial direction of the arc-shaped battery, the second direction is along the circumferential direction of the arc-shaped battery, and the third direction is along the axial direction of the arc-shaped battery.

[0060] The curved battery of this embodiment may further include a tab assembly 200, which may include a positive tab assembly 220 and a negative tab assembly 210. The positive tab assembly 220 may include a plurality of positive tabs 221, which are connected to the positive electrode sheets 122 in a one-to-one correspondence. The negative tab assembly 210 may include a plurality of negative tabs 211, which are connected to the negative electrode sheets 121 in a one-to-one correspondence.

[0061] In this embodiment, the battery cell 100 can be stacked in a Z-stack manner. Figure 3 As shown in FIG. 1 , a continuous diaphragm 110 is bent in a Z shape to form multiple diaphragm layers 111 , a negative electrode sheet 121 is sandwiched between the first diaphragm layer 111 and the second diaphragm layer 111 , a positive electrode sheet 122 is sandwiched between the second diaphragm layer 111 and the third diaphragm layer 111 , and so on. The negative electrode sheet 121 , the diaphragm layer 111 and the positive electrode sheet 122 are stacked alternately in sequence. In this way, the diaphragm layer 111 can separate the negative electrode sheet 121 from the positive electrode sheet 122 .

[0062] For example, the number of diaphragm layers 111 can be 5, 10, 20, etc. Any three adjacent diaphragm layers 111 taken along the thickness direction of the battery cell 100 must satisfy the following conditions: the first side 1111 of the first diaphragm layer 111 is adjacent to the first side 1111 of the second diaphragm layer 111, and the second side 1112 of the second diaphragm layer 111 is adjacent to the second side 1112 of the third diaphragm layer 111.

[0063] It is understandable that in the Z-stacked battery cell 100 , the diaphragm 110 forms a V-shaped sharp corner at the corner, which causes the diaphragm 110 at the corner to be subjected to greater stress, thereby causing the diaphragm 110 to be easily wrinkled.

[0064] When the battery cell 100 is bent, the diaphragm layer 111 close to the first side needs to move along a longer arc, which causes the diaphragm layer 111 in this area to be stretched in the arc direction, and the diaphragm layer 111 close to the second side needs to move along a shorter arc, which causes the diaphragm layer 111 in this area to be compressed in the arc direction, which in turn causes uneven force on each diaphragm layer 111, which in turn causes stress concentration in some areas of the diaphragm 110, thereby exacerbating the problem of wrinkling of the diaphragm 110.

[0065] In this embodiment, for any three adjacent diaphragm layers 111, the first side edge 1111 of the first diaphragm layer 111 and the first side edge 1111 of the second diaphragm layer 111 are partially continuous and partially disconnected, and the second side edge 1112 of the second diaphragm layer 111 and the second side edge 1112 of the third diaphragm layer 111 are partially continuous and partially disconnected, that is, an incision 1113 is set between two adjacent first side edges 1111, and an incision 1113 is set between two adjacent second side edges 1112.

[0066] In this way, the incision 1113 can reduce the degree of coupling between the two adjacent diaphragm layers 111, thereby reducing the stress transmission path between the two adjacent diaphragm layers 111. Taking the second diaphragm layer 111 of the three adjacent diaphragm layers 111 as an example, if the incision 1113 is not set on both sides of the second diaphragm layer 111 along the second direction, one side of the second diaphragm layer 111 along the second direction is completely coupled with the side of the first diaphragm layer 111 along the second direction, and the stresses interact with each other. The other side of the second diaphragm layer 111 along the second direction is completely coupled with the other side of the third diaphragm layer 111 along the second direction, and the stresses interact with each other, thereby causing stress concentration in the diaphragm 110.

[0067] If cuts 1113 are provided on both sides of the second diaphragm layer 111 along the second direction, the cuts 1113 partially decouple the first diaphragm layer 111 from the second diaphragm layer 111, and partially decouple the second diaphragm layer 111 from the third diaphragm layer 111, so as to reduce the stress transfer path between adjacent diaphragm layers 111, and facilitate the release of stress in the diaphragm layer 111, so as to prevent stress concentration in the diaphragm 110, and further prevent the diaphragm 110 from wrinkling, thereby preventing the arc-shaped battery from having problems such as lithium deposition, increased internal resistance, and thermal runaway due to wrinkling of the diaphragm 110.

[0068] In addition, since there are cutouts 1113 between adjacent diaphragm layers 111, it is not easy for the diaphragm 110 to accumulate at the corners after the battery cell 100 is bent. In this way, local thick areas can be prevented from forming at the corners of the curved battery, thereby preventing local over-temperature areas from occurring in the curved battery, thereby preventing thermal runaway of the curved battery, and preventing the diaphragm layer 111 from rubbing against the electrode 120 after accumulation, thereby preventing microporous defects in the diaphragm 110, thereby improving the service life of the diaphragm 110, thereby improving the service life of the curved battery and preventing thermal runaway of the battery.

[0069] It can be understood that, compared with completely disconnecting the two adjacent diaphragm layers 111, since the adjacent diaphragm layers 111 are still partially coupled, the two adjacent diaphragm layers 111 can have a greater restraining force on the electrode 120 sandwiched between the two diaphragm layers 111, thereby facilitating the restraint of the expansion of the battery cell 100 during charging and discharging, especially when the negative electrode 121 contains silicon-based materials, the expansion of the negative electrode 121 is more serious, and the two adjacent diaphragm layers 111 can effectively restrain the expansion of the negative electrode 121.

[0070] It should be noted that the cutout 1113 can be formed before lamination, or can be formed simultaneously with lamination. In this way, the diaphragm 110 can be cut while Z-stacked, without affecting production efficiency and allowing the cutout 1113 to be quickly formed. Alternatively, the cutout 1113 can be formed after lamination, which does not require modification of the existing lamination machine and reduces the difficulty of process implementation.

[0071] The bending of the battery cell 100 can be performed before the formation process so that the electrode 120 can be deformed and hardened in a relatively soft state. This can avoid problems such as breakage, internal short circuit, and capacity reduction of the electrode 120. It can also enable the curved battery to maintain its own curvature after full charge or cycle expansion, making it less likely to rebound and ensuring dimensional stability.

[0072] During specific implementation, a portion of the diaphragm 110 may be cut off or trimmed off by die cutting, knife cutting, laser cutting, or the like to form the incision 1113 .

[0073] The curved battery of the embodiment of the present application includes a battery cell 100, which includes a separator 110 and an electrode 120, wherein the electrode 120 includes a positive electrode 122 and a negative electrode 121, and the separator 110 includes a separator layer 111, and the separator layer 111 includes a first side 1111, a second side 1112 and a cutout 1113. Since, among the three adjacent diaphragm layers 111, the first side 1111 of the first diaphragm layer 111 is adjacent to the first side 1111 of the second diaphragm layer 111, and the second side 1112 of the second diaphragm layer 111 is adjacent to the second side 1112 of the third diaphragm layer 111, the diaphragm 110 can be continuously bent to form multiple diaphragm layers 111, so that the negative electrode sheet 121 sandwiched between the first diaphragm layer 111 and the second diaphragm layer 111 can be subjected to a larger restraining force, and the positive electrode sheet 122 sandwiched between the second diaphragm layer 111 and the third diaphragm layer 111 can be subjected to a larger restraining force, thereby preventing relative movement between the negative electrode sheet 121 and the diaphragm 110, and the positive electrode sheet 122 and the diaphragm 110, and can effectively restrain the expansion of the positive electrode sheet 122 and the negative electrode sheet 121. Because the cutout 1113 is provided between two adjacent first sides 1111, and the cutout 1113 is provided between two adjacent second sides 1112, when the diaphragm 110 is repeatedly bent to form the diaphragm layer 111, the cutout 1113 can effectively release stress at the corners of the diaphragm 110, thereby preventing stress concentration at the corners of the diaphragm 110 and improving the phenomenon of wrinkling of the diaphragm 110. When the battery cell 100 is bent, the cutout 1113 can reduce the degree of coupling between adjacent diaphragm layers 111, thereby reducing the stress transmission path between the two adjacent diaphragm layers 111. The cutout 1113 can also effectively release and relieve the tensile or compressive stress of the diaphragm layer 111, preventing stress concentration in the diaphragm layer 111 and improving the phenomenon of wrinkling of the diaphragm 110, thereby reducing the probability of lithium deposition, increased internal resistance, and thermal runaway in curved batteries due to wrinkling of the diaphragm 110. Moreover, since a cutout 1113 is provided between two adjacent first sides 1111 and a cutout 1113 is provided between two adjacent second sides 1112, the diaphragm 110 can be effectively prevented from accumulating at the corners of the battery cell 100 when the battery cell 100 is bent, thereby preventing the formation of local over-temperature zones at the corners of the battery cell 100 and reducing micropore defects caused by the accumulation of the diaphragm 110, thereby reducing the probability of thermal runaway of the arc battery and improving the reliability of the battery cell 100 packaging.

[0074] In some embodiments, multiple cuts 1113 may be provided along a third direction between two adjacent first sides 1111 and between two adjacent second sides 1112 , that is, the cuts 1113 and non-cuts are alternately provided to form a structure similar to a dotted line.

[0075] In some embodiments, two non-cuts are arranged on both sides of the cut 1113 along the third direction, that is, the non-cut, the cut 1113 and the non-cut are arranged in sequence along the third direction, and the middle parts of the two adjacent diaphragm layers 111 are disconnected and continuous on both sides along the third direction. In this way, the cut 1113 can reduce the degree of coupling between the two adjacent diaphragm layers 111 to block the continuous force on the diaphragm 110 and relieve the stress of the diaphragm 110.

[0076] In a possible implementation, at least two cutouts 1113 are provided on both sides of the first side 1111 along the third direction, and / or at least two cutouts 1113 are provided on both sides of the second side 1112 along the third direction.

[0077] That is to say, in this setting, the incision 1113, the non-incision and the incision 1113 are arranged in sequence along the third direction, and the middle parts of the two adjacent diaphragm layers 111 are continuous and disconnected on both sides along the third direction. In this way, the total length of the incision 1113 can be effectively increased, which is conducive to reducing the degree of coupling between the diaphragm layers 111, and is conducive to releasing stress through the incision 1113, and is conducive to preventing the accumulation of the diaphragm 110 at the four corners of the battery cell 100, and is conducive to reducing the microporous defects of the diaphragm 110, thereby preventing thermal runaway of the arc battery, and reducing the accumulation of the diaphragm 110 at the corners is beneficial to the packaging of the battery cell 100 and the shell.

[0078] In a possible implementation, the at least two cutouts 1113 are symmetrically arranged relative to a center line of the diaphragm layer 111 along the second direction.

[0079] It should be noted that the symmetrical arrangement means that the two cutouts 1113 are symmetrical in position relative to the midline of the diaphragm layer 111 along the second direction, and the sizes of the two cutouts 1113 are the same.

[0080] If the incision 1113 is only provided on one side of the diaphragm layer 111 along the second direction, and the incision 1113 is not provided on the other side of the diaphragm layer 111 along the second direction, or if the incisions 1113 on both sides of the diaphragm layer 111 along the second direction are inconsistent in size, it will cause uneven force on the opposite sides of the diaphragm layer 111 along the second direction. When the battery cell 100 is bent, the pole piece 120 is likely to shift relative to the diaphragm layer 111 due to the uneven force, and it will also cause stress concentration on one or both sides of the diaphragm 110 along the second direction, thereby causing wrinkles in the diaphragm 110 and reducing the interface flatness of the battery cell 100.

[0081] Therefore, in this embodiment, the incision 1113 is symmetrically arranged relative to the midline of the diaphragm layer 111 along the second direction, so that the relative forces on the two sides of the diaphragm layer 111 along the second direction are uniform, thereby effectively restraining the pole piece 120 and improving the wrinkling phenomenon of the diaphragm 110, thereby preventing lithium deposition in the arc-shaped battery.

[0082] Reference Figures 6 to 9 As shown, in some embodiments, a dimension h of a single cutout 1113 along the third direction satisfies: 1 mm ≤ h ≤ 80 mm.

[0083] On the one hand, it can prevent the dimension h of a single incision 1113 along the third direction from being too small. For example, when h is less than 1 mm, the incision 1113 will not be able to effectively release stress, and thus will not be able to effectively improve the wrinkling phenomenon of the diaphragm 110, and the incision 1113 will not be able to better improve the problem of diaphragm 110 stacking. On the other hand, it can prevent the dimension h of a single incision 1113 along the third direction from being too large. For example, when h is greater than 80 mm, the two adjacent diaphragm layers 111 may be completely disconnected, which will destroy the mechanical properties of the diaphragm 110, and thus the two adjacent diaphragm layers 111 will not be able to effectively constrain the pole piece 120, thereby reducing the deformation resistance of the battery cell 100.

[0084] Therefore, when the dimension h of a single incision 1113 along the third direction is between 1 mm and 80 mm, the coupling degree between adjacent diaphragm layers 111 can be effectively reduced through the incision 1113 to reduce the stress transmission path, and the stress can be effectively released through the incision 1113, thereby preventing stress concentration in the diaphragm 110, and the two adjacent diaphragm layers 111 can effectively constrain the electrode 120, thereby preventing relative movement between the electrode 120 and the diaphragm 110, thereby improving the deformation resistance of the battery cell 100 during falling and impact conditions, and improving the cycle capacity retention rate of the arc battery.

[0085] Exemplarily, the dimension h of a single incision 1113 along the third direction can be any one of 1 mm, 2 mm, 5 mm, 10 mm, 12 mm, 15 mm, 20 mm, 22 mm, 40 mm, 53 mm, 60 mm, 70 mm, and 80 mm, or be within any two value ranges.

[0086] In some embodiments, the arc length L of the battery cell 100 and the dimension h of the single cutout 1113 along the third direction satisfy: 0.05≤h / L≤0.4.

[0087] It should be noted that, when the third direction is the circumferential direction of the arc-shaped battery, it means that the cutout 1113 extends along the circumferential direction of the arc-shaped battery, and the extending direction of the cutout 1113 is consistent with the arc length direction of the battery cell 100 .

[0088] If h / L is less than 0.05, the proportion of the cutout 1113 will be too small, and the diaphragm 110 will easily wrinkle due to stress concentration, and the corners of the battery cell 100 will easily accumulate. If h / L is greater than 0.4, the proportion of the cutout 1113 will be too large, which will reduce the mechanical strength of the diaphragm 110 and weaken the binding force of the diaphragm 110 on the electrode 120, thereby reducing the deformation resistance of the battery cell 100.

[0089] In this embodiment, h / L is between 0.05 and 0.4. In this way, by setting the cutouts 1113 in appropriate proportions, the diaphragm 110 can be prevented from wrinkling, thereby preventing lithium deposition in the curved battery. The mechanical strength of the diaphragm 110 can also be taken into account to improve the deformation resistance of the curved battery, thereby improving the cycle capacity retention rate of the curved battery.

[0090] For example, h / L can be any one of 0.05, 0.08, 0.1, 0.13, 0.2, 0.25, 0.3, 0.33, and 0.4, or be within a range of any two values.

[0091] In a specific implementation, h can change according to the change of L, so that the length of the incision 1113 can adapt to the battery cells 100 with different arc lengths. For example, when L increases, h can be adaptively increased so that h is adapted to L, so that the incision 1113 can effectively release the stress of the battery cell 100 and enable the diaphragm 110 to have a certain mechanical strength.

[0092] In some embodiments, the arc length L of the battery cell 100 satisfies the following: 20 mm ≤ L ≤ 200 mm. For example, the arc length L of the battery cell 100 can be any one of 20 mm, 42 mm, 65 mm, 80 mm, 100 mm, and 200 mm, or within a range of any two values. This prevents the battery cell 100 from being bent too much, thereby preventing stress concentration in the battery cell 100 and better matching the curvature of the wearable device.

[0093] In one possible implementation, the bending radius R of the battery cell 100 and the dimension h of a single cutout 1113 along the third direction satisfy the following relationship: 0.003 < h / R < 1.3. This configuration allows the dimension h of a single cutout 1113 along the third direction to match the bending radius R of the battery cell 100. Consequently, the cutout 1113 can effectively release bending stress in separators 110 with varying degrees of curvature, thereby preventing the separator 110 from wrinkling, thereby preventing lithium deposition and increased internal resistance in curved batteries. Furthermore, the coupling between adjacent separator layers 111 can be maintained to maintain the mechanical strength of the separator 110, thereby improving the deformation resistance of curved batteries.

[0094] It should be noted that those skilled in the art can test the deformation resistance of curved batteries by testing the cycle capacity retention rate of curved batteries. For example, after the curved battery has been cycled for 1000T, if the cycle capacity retention rate of the curved battery is low, it means that the front and rear deformation of the curved battery is more serious, which in turn causes the interface of the curved battery to be loose, thereby reducing the cycle capacity retention rate. If the cycle capacity retention rate of the curved battery is high, the interface of the curved battery is relatively tight, and the front and rear deformation of the curved battery is relatively slight.

[0095] Reference Figure 10 As shown, in some embodiments, the bending radius R of the battery cell 100 satisfies: 10mm≤R≤3600mm, and the central angle α of the battery cell 100 satisfies: 3°<α<180°. This can prevent the battery cell 100 from being bent too much, thereby increasing the bending stress of the battery cell 100. The battery cell 100 can also be set with a corresponding bending radius or central angle according to the curvature of the wearable device, so that the curved battery is compatible with the wearable device.

[0096] The arc length L of the battery cell 100 , the bending radius R of the battery cell 100 , and the central angle α of the battery cell 100 satisfy: L=απR / 180.

[0097] For example, the bending radius R of the battery cell 100 can be any one of 10 mm, 20 mm, 50 mm, 100 mm, 155 mm, 2000 mm, and 3600 mm, or within any two numerical ranges. The central angle α of the battery cell 100 can be any one of 4°, 30°, 45°, 60°, 90°, 120°, and 175°, or within any two numerical ranges.

[0098] Reference Figure 6 、 Figure 7 As shown, in one possible implementation, the size of the cutout 1113 of a single diaphragm layer 111 along the second direction is W1. The single diaphragm layer 111 includes a main portion 1114 and a protruding portion 1115 that are interconnected. The protruding portion 1115 is provided on at least one side of the main portion 1114 along the second direction. The projection of the negative electrode sheet 121 on the diaphragm layer 111 overlaps with the main portion 1114, and the projection of the negative electrode sheet 121 on the diaphragm layer 111 is offset from the protruding portion 1115. The size of the protruding portion 1115 along the second direction is W2. W1 and W2 satisfy the following relationship: 0.5*W2≤W1≤W2.

[0099] In this way, since the diaphragm layer 111 has a main body 1114 and a protruding portion 1115, the diaphragm layer 111 can not only completely cover the negative electrode sheet 121, but also protrude from the negative electrode sheet 121, thereby completely isolating the positive electrode sheet 122 and the negative electrode sheet 121. By setting a cutout 1113 on the protruding portion 1115 and making W1 between 0.5*W2 and W2, a wider cutout 1113 can be formed to effectively release stress through the cutout 1113 and reduce the total area of ​​the diaphragm 110, thereby avoiding accumulation of the diaphragm 110 at the corners of the battery cell 100, and avoiding contact between the positive electrode sheet 122 and the negative electrode sheet 121 due to processing the cutout 1113, thereby improving the safety of the battery cell 100.

[0100] For example, W1 / W2 can be any one of 0.5, 0.6, 0.7, 0.8, 0.9, 1, or within a range of any two values.

[0101] It should be noted that, referring to Figure 9 As shown, when the diaphragm 110 is unfolded, the cutouts 1113 of the two adjacent diaphragm layers 111 merge into one, and at this time, W3 = 2*W1.

[0102] In one possible implementation, the negative electrode sheet 121 includes a negative electrode active coating, which is disposed on at least one side of the negative electrode sheet 121 in the thickness direction. The negative electrode active coating includes a silicon-based material, and the silicon content G of the negative electrode active coating and the dimension h of a single cutout 1113 along the third direction satisfy the following conditions: 2 ≤ h / G ≤ 1600. Furthermore, the silicon content G of the negative electrode active coating satisfies the following conditions: 5% ≤ G ≤ 60%.

[0103] It can be understood that using silicon-based materials as the negative electrode active material of the negative electrode sheet 121 and adding more than 5% of silicon-based materials can effectively increase the gram capacity of the negative electrode sheet 121, thereby increasing the volume energy density of the arc battery. Since the silicon-based material itself expands and contracts severely, the silicon element content G of the negative electrode active coating needs to be controlled within 60% to prevent the expansion of the negative electrode sheet 121 from exceeding the range that the diaphragm 110 can withstand.

[0104] When the silicon content G of the negative electrode active coating is high, the expansion stress of the negative electrode sheet 121 increases. Therefore, a suitable cutout 1113 is required to release the expansion stress of the negative electrode sheet 121 on the separator 110. In this embodiment, h / G is greater than or equal to 2 to effectively release the expansion stress from the negative electrode sheet 121 through the cutout 1113. h / G is less than or equal to 1600 to prevent the cutout 1113 from being too large, thereby increasing the constraint of the separator 110 on the negative electrode sheet 121 and preventing severe deformation of the battery cell 100 during expansion. h / G is less than or equal to 1600 to prevent the negative electrode sheet 121 from contacting the positive electrode sheet 122 after expansion, thereby preventing the battery cell 100 from shorting.

[0105] For example, h / G can be any value among 2, 5, 10, 20, 100, 1000, 1600, or any range between two values. G can be any value among 5%, 12%, 20%, 42%, 50%, 60%, or any range between two values.

[0106] In some embodiments, the thickness T of the negative electrode active coating on a single side of the negative electrode sheet 121 and the dimension h of a single cutout 1113 along the third direction satisfy the following relationship: 6.5 ≤ h / T ≤ 2000. Because a greater thickness T of the negative electrode active coating increases the stress gradient when the negative electrode sheet 121 is bent, a longer cutout 1113 is required to disperse the stress of the negative electrode sheet 121. Therefore, setting h / T between 6.5 and 2000 allows the dimension h of a single cutout 1113 along the third direction to match the thickness T of the negative electrode active coating, effectively releasing the stress of the negative electrode sheet 121 through the cutout 1113.

[0107] For example, h / T may be any one of 6.5, 10, 100, 200, 300, 500, 1000, and 2000, or be within a range of any two values.

[0108] In some embodiments, the thickness T of the negative electrode active coating satisfies the following relationship: 0.04 mm ≤ T ≤ 0.15 mm. For example, the thickness T of the negative electrode active coating can be any one of 0.04 mm, 0.05 mm, 0.08 mm, 0.1 mm, and 0.15 mm, or within a range of any two values, so as to adjust the thickness of the negative electrode active coating according to curved batteries of different capacities.

[0109] In some embodiments, the volume average particle size D of the silicon-based material and the dimension h of a single cutout 1113 along the third direction satisfy: 70≤h / D≤16000.

[0110] It is understandable that smaller silicon particles can better relieve the stress caused by volume expansion, while larger particles are more likely to cause greater volume changes and stress concentration. Therefore, the dimension h of a single incision 1113 along the third direction needs to match the volume average particle size D of the silicon-based material, and h / D should be controlled between 70 and 16000 to effectively release the expansion stress of the negative electrode sheet 121 on the diaphragm 110 through the incision 1113.

[0111] For example, h / D may be any one of 70, 100, 120, 200, 1000, 10000, and 16000, or be within a range of any two values.

[0112] In a possible implementation, the negative electrode sheet 121 further includes a negative electrode current collector, and the tensile strength TS of the negative electrode current collector along the circumference of the arc-shaped battery and the arc length L of the battery cell 100 satisfy: 0.05≤L / TS≤0.2.

[0113] It can be understood that when the battery cell 100 is bent, the negative electrode current collector is stretched along the circumference of the curved battery, and the negative electrode current collector is also subjected to bending stress. When the arc length L of the battery cell 100 is shorter, the bending stress to which the battery cell 100 is subjected is greater. If the stress of the negative electrode current collector is too large, the negative electrode current collector is prone to problems such as wrinkles, cracks or fractures, which in turn leads to a reduction in the cycle life of the curved battery.

[0114] Therefore, it is necessary to set the tensile strength TS of the negative electrode current collector according to the arc length L of the battery cell 100 so that L / TS is between 0.05 and 0.2 to prevent L / TS from being too high, thereby enabling the negative electrode current collector to withstand sufficient tensile stress and bending stress to prevent the negative electrode sheet 121 from wrinkling or breaking during cycling, and to prevent L / TS from being too low, thereby preventing the tensile strength TS of the negative electrode current collector from being too high and increasing costs.

[0115] The tensile strength TS of the negative electrode current collector satisfies the following relationship: 400 MPa≤TS≤1000 MPa, so that the tensile strength of the negative electrode current collector can be set according to the arc length of the battery cell 100 .

[0116] For example, L / TS can be any one of 0.05, 0.1, 0.15, 0.18, and 0.2, or within any two numerical ranges. The tensile strength TS of the negative electrode current collector can be any one of 400 MPa, 500 MPa, 650 MPa, 720 MPa, 880 MPa, and 1000 MPa, or within any two numerical ranges.

[0117] In some embodiments, the circumferential elongation EL of the negative electrode current collector of the curved battery and the arc length L of the battery cell 100 satisfy the following conditions: 250 ≤ L / EL ≤ 6670. The circumferential elongation EL of the negative electrode current collector of the curved battery satisfies the following conditions: 3% ≤ EL ≤ 8%. This facilitates setting the elongation EL of the negative electrode current collector according to the arc length L of the battery cell 100, such that L / EL is between 250 and 6670. This allows the negative electrode current collector to withstand sufficient tensile and bending strains, thereby preventing wrinkling and breakage of the negative electrode sheet 121 during cycling.

[0118] For example, L / EL can be any one of 250, 500, 800, 900, 1000, 1110, 1250, 1500, 3000, 4000, and 6629, or within any two numerical ranges. The elongation EL of the negative electrode current collector can be any one of 3%, 3.3%, 4.1%, 5.5%, 6%, and 8%, or within any two numerical ranges.

[0119] Reference Figure 11 As shown, in one possible implementation, at least one protrusion 1221 is provided on one side of the positive electrode sheet 122, and a concave portion 1222 corresponding to the protrusion 1221 is provided on the other side of the positive electrode sheet 122. The protrusion 1221 protrudes toward the first side of the battery cell 100, and the concave portion 1222 is recessed toward the first side of the battery cell 100. The protrusion height PH of the protrusion 1221 satisfies the following conditions: 3 μm ≤ PH ≤ 30 μm.

[0120] Thus, by providing the protrusions 1221 and the recesses 1222 on the positive electrode sheet 122, the mechanical strength of the positive electrode sheet 122 can be improved, thereby reducing the probability of the positive electrode sheet 122 breaking due to bending. The recesses 1222 can also provide a wetting space for the electrolyte, thereby improving the wettability of the electrolyte to the electrode sheet 120. Furthermore, providing the protrusions 1221 and the recesses 1222 on the positive electrode sheet 122 can increase the surface roughness of the positive electrode sheet 122, thereby preventing relative movement between the positive electrode sheet 122 and the separator 110, thereby improving the deformation resistance of the battery cell 100.

[0121] Since the positive electrode sheet 122 has a convex portion 1221 , and the protruding direction of the convex portion 1221 is consistent with the bending direction of the battery cell 100 , the convex portion 1221 can support the diaphragm layer 111 after the battery cell 100 is bent, thereby preventing the diaphragm layer 111 from wrinkling.

[0122] Illustratively, the protrusion height PH of the protrusion 1221 can be any one of 3μm, 4μm, 5μm, 6μm, 6.5μm, 8μm, 9μm, 10μm, 11μm, 12μm, 20μm, 22μm, 25μm, and 30μm, or be within any two numerical ranges.

[0123] It should be noted that the positive electrode sheet 122 may be provided with multiple protrusions 1221 and recesses 1222 corresponding to the multiple protrusions 1221. The width of a single recess 1222 may be 1-8 mm. For example, the width of a single recess 1222 may be 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 7 mm, or 8 mm. The spacing between two adjacent recesses 1222 is 1 mm to 10 mm. For example, the spacing between two adjacent recesses 1222 may be 1 mm, 2 mm, 2.5 mm, 3 mm, 4 mm, 5 mm, 8 mm, or 10 mm.

[0124] The following describes the structural parameters of the battery and related tests.

[0125] 1. Preparation of Battery Cell 100

[0126] The positive electrode sheet 122, separator 110, and negative electrode sheet 121 are stacked in sequence to form a battery cell 100. At this point, the separator 110 is Z-shaped, and the battery cell 100 is in the shape of a rectangular parallelepiped. During the stacking process, the separator 110 at the four corners of the battery cell 100 is cut to form cutouts 1113. The length of the cutouts 1113 is h, thereby disconnecting the separators 110 on both sides of the battery cell 100 in the height direction and leaving the separator 110 in the middle continuous.

[0127] 2. Battery Cell 100 Bend

[0128] The battery cell 100 is placed on an arc-shaped fixture and subjected to hot pressing treatment, so that the battery cell 100 is bent and presents an arc shape, wherein the hot pressing temperature range is 50-85° C., the hot pressing time range is 0.25 min-8 min, and the hot pressing pressure range is 0.3-1.3 MPa.

[0129] 3. Assembly

[0130] The battery cell 100 is placed in a shell, and after the electrolyte is injected, it goes through a sealing, aging, formation and secondary sealing process to form a curved battery.

[0131] The separators 110 on both sides of Examples 1 to 10 are both provided with cutouts 1113 . The structural parameters of the cutouts 1113 and other parameters of the battery cell 100 are shown in Tables 1 and 2. The separator 110 of Comparative Example 1 is not provided with the cutouts 1113 .

[0132] Table 1 Structural parameters of curved batteries

[0133] Serial number h(mm) R(mm) α(°) L(mm) h / L h / R W1 / W2 Real 1 1 10 177 30.88 0.03 0.10 0.5 Real 2 10 20 160 55.82 0.18 0.50 0.5 Real 3 10 20 145 50.59 0.20 0.50 0.8 Real 4 10 40 90 62.80 0.16 0.25 0.8 Real 5 10 100 90 157.00 0.06 0.10 0.8 Real 6 10 190 60 198.87 0.05 0.16 0.8 Real 7 30 190 60 198.87 0.15 0.26 0.8 Real 8 50 190 60 198.87 0.25 0.42 0.8 Real 9 80 190 60 198.87 0.40 0.42 0.8 Real 10 80 3600 3 188.40 0.42 0.02 0.8 1 / 20 160 55.82 / / /

[0134] Table 2 Structural parameters of curved batteries

[0135]

[0136]

[0137] Test Method

[0138] 1. Lithium deposition test: The obtained curved battery was charged to a full charge state (SOC = 100%), and then disassembled in a humidity-free environment to observe whether the surface of the negative electrode is golden yellow and whether there is any silvery white / silver gray / dark gray substance. If there is an area of ​​silvery white / silver gray or dark gray substance, it is considered that the battery has undergone lithium deposition. A total of 20 batteries were tested. For example, 18 / 20 means that 18 batteries did not undergo lithium deposition.

[0139] II. 1000T Capacity Retention Test: The arc-shaped batteries prepared in the examples and comparative examples were charged at 25°C at 3.5C-4.18V, 2.7C-4.18V, 2.31C-4.28V, 1.7C-4.4V (1C cut-off), 1C-4.53V (0.7C cut-off), 0.7C-4.565V (0.164C cut-off), and discharged at 1.5C-3V to 0.7C-3V for 1000 cycles. The capacity of the arc-shaped battery at the 1000th cycle was divided by the capacity of the arc-shaped battery at the first cycle to obtain the cycle capacity retention rate.

[0140] 3. Oven temperature test: The fully charged curved battery is placed in an oven and heated at a rate of 5±2℃ / min. When the temperature inside the oven reaches 130℃, it is kept constant for 60 minutes. If there is no fire or explosion, the test is passed. A total of 20 batteries are tested. For example, 18 / 20 means: 18 batteries passed the oven temperature test.

[0141] Table 3 Test results of curved batteries

[0142]

[0143]

[0144] As shown in Table 3 above, when the diaphragm 110 is provided with the notch 1113, the notch 1113 can effectively release the stress of the diaphragm 110, thereby effectively preventing the diaphragm 110 from wrinkling, thereby effectively reducing the probability of lithium plating in the curved battery and effectively improving the furnace temperature test pass rate of the curved battery. When h / L increases, the battery's 1000T cycle capacity retention rate decreases, indicating that the battery's deformation resistance deteriorates. When the diaphragm 110 is not provided with the notch 1113, the diaphragm 110 is prone to wrinkling, the curved battery is prone to lithium plating, and the probability of thermal runaway in the curved battery is also higher.

[0145] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A curved battery, characterized in that: The battery cell comprises a first side and a second side disposed opposite to each other along a first direction, wherein the second side of the battery cell is bent toward the first side of the battery cell; The battery cell includes a diaphragm and pole pieces, the pole pieces include a positive pole piece and a negative pole piece, the diaphragm includes a plurality of diaphragm layers arranged along the first direction, and a single pole piece is sandwiched between two adjacent diaphragm layers; Each of the diaphragm layers comprises a first side and a second side arranged opposite to each other along the second direction, and among the three adjacent diaphragm layers, the first side of the first diaphragm layer is adjacent to the first side of the second diaphragm layer, and the second side of the second diaphragm layer is adjacent to the second side of the third diaphragm layer; A cutout is provided between two adjacent first side edges and between two adjacent second side edges, and the cutout extends along a third direction; The first direction is along the radial direction of the arc-shaped battery, one of the second direction and the third direction is along the axial direction of the arc-shaped battery, and the other is along the circumferential direction of the arc-shaped battery.

2. The curved battery according to claim 1, characterized in that At least two of the cutouts are provided on both sides of the first side along the third direction, and / or at least two of the cutouts are provided on both sides of the second side along the third direction.

3. The battery according to claim 1, characterized in that At least two of the cutouts are symmetrically arranged relative to a center line of the diaphragm layer along the second direction.

4. The curved battery according to any one of claims 1 to 3, characterized in that: A dimension h of a single incision along the third direction satisfies: 1 mm ≤ h ≤ 80 mm.

5. The curved battery according to claim 4, characterized in that The arc length L of the battery cell and the dimension h of a single incision along the third direction satisfy the following conditions: 0.05≤h / L≤0.4; And / or, the arc length L of the battery cell satisfies: 20 mm ≤ L ≤ 200 mm.

6. The curved battery according to claim 4, characterized in that The bending radius R of the battery cell and the dimension h of a single incision along the third direction satisfy the following conditions: 0.003<h / R<1.3; And / or, the bending radius R of the battery cell satisfies: 10 mm ≤ R ≤ 3600 mm; And / or, the central angle α of the battery cell satisfies: 3°<α<180°.

7. The curved battery according to claim 4, characterized in that The size of the cutout of a single diaphragm layer along the second direction is W1; The single diaphragm layer includes a main portion and a protruding portion connected to each other, the protruding portion being provided on at least one side of the main portion along the second direction, the projection of the negative electrode sheet on the diaphragm layer overlapping with the main portion, the projection of the negative electrode sheet on the diaphragm layer being staggered from the protruding portion, the incision being provided in the protruding portion, and the dimension of the protruding portion along the second direction being W2; W1 and W2 satisfy: 0.5*W2≤W1≤W2.

8. The curved battery according to claim 4, characterized in that The negative electrode sheet includes a negative electrode active coating, the negative electrode active coating is provided on at least one side of the negative electrode sheet in a thickness direction, the negative electrode active coating includes a silicon-based material, and the silicon content G of the negative electrode active coating and the dimension h of a single incision along the third direction satisfy: 2≤h / G≤1600; And / or, the silicon content G of the negative electrode active coating satisfies: 5%≤G≤60%.

9. The curved battery according to claim 5 or 6, characterized in that: The negative electrode sheet further includes a negative electrode current collector, and the tensile strength TS of the negative electrode current collector along the circumference of the arc-shaped battery and the arc length L of the battery cell satisfy: 0.05≤L / TS≤0.2; And / or, the elongation EL of the negative electrode current collector along the circumferential direction of the arc-shaped battery and the arc length L of the battery cell satisfy: 250≤L / EL≤6670.

10. The curved battery according to any one of claims 1 to 3, characterized in that: At least one convex portion is provided on one side surface of the positive electrode sheet, and a concave portion corresponding to the convex portion is provided on the other side surface of the positive electrode sheet, wherein the convex portion is convex toward the first side of the battery cell, and the concave portion is concave toward the first side of the battery cell; The protrusion height PH of the protrusion satisfies: 3 μm≤PH≤30 μm.

Images