Secondary battery and electronic device

Abstract

The embodiment of the utility model provides a kind of secondary battery and electronic device, secondary battery includes: shell, define accommodating cavity;Cover plate component, for sealing shell;Two groups of electrode components, oppositely set in accommodating cavity, cover plate component includes adapter piece, two groups of electrode components include main body and negative electrode tab extending from main body respectively, negative electrode tab is electrically connected to adapter piece;First adhesive tape, set in the inner side of negative electrode tab away from shell;Reinforcing layer, at least part of reinforcing layer is located on negative electrode tab, wherein, in the thickness direction of each group of electrode components, the orthographic projection of reinforcing layer is completely located in first adhesive tape.The above technical scheme of the utility model, at least can prevent negative electrode tab to wrinkle by reinforcing layer, simultaneously avoid reinforcing layer to fall off and influence battery performance.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and more specifically, to a secondary battery and electronic device. Background Technology

[0002] In the field of new energy power batteries, the application of rechargeable batteries is becoming increasingly widespread. These batteries (such as lithium-ion batteries) can be used in vehicles, energy storage, mobile phones, tablets, wearable devices, power banks, e-cigarettes, digital products, power tools, power units, and other electronic devices. One type of rechargeable battery is the prismatic battery, which includes a casing and an electrode assembly. The electrode assembly consists of a positive electrode, a first separator, a negative electrode, and a second separator, which are stacked sequentially and wound into a flat rectangular shape before being encapsulated in the casing. The negative electrode tab extends from the main body of the electrode assembly; however, the problem of the negative electrode tab easily wrinkling needs to be solved. Utility Model Content

[0003] In view of the problems existing in the related technologies, the purpose of this utility model is to provide a secondary battery and electronic device that can at least prevent the negative electrode tab from wrinkling through a reinforcing layer, and at the same time avoid the reinforcing layer from falling off and affecting the battery performance.

[0004] To achieve the above objectives, embodiments of the present invention provide a secondary battery comprising: a housing defining a receiving cavity; a cover assembly for sealing the housing; two sets of electrode assemblies disposed opposite to each other within the receiving cavity, the cover assembly including an adapter piece, the two sets of electrode assemblies each including a main body and a negative electrode tab extending from the main body, the negative electrode tab being electrically connected to the adapter piece; a first adhesive tape disposed on the inner side of the negative electrode tab opposite to the housing; and a reinforcing layer, at least a portion of which is located on the negative electrode tab, wherein, in the thickness direction of each set of electrode assemblies, the orthographic projection of the reinforcing layer is completely located within the first adhesive tape.

[0005] In some embodiments, the negative electrode tab includes a bent portion and a connecting portion, the connecting portion being connected to an adapter piece, the bent portion being connected between the body and the connecting portion, and a reinforcing layer being located at the bent portion; the first adhesive tape includes a first adhesive region, a second adhesive region, and a non-adhesive region located between the first adhesive region and the second adhesive region, the first adhesive region covering the body, the second adhesive region covering the connecting portion, and in the thickness direction of each electrode assembly, the orthogonal projection of the reinforcing layer is completely located in the non-adhesive region.

[0006] In some embodiments, each electrode assembly includes two electrode assemblies, the negative tabs of the two electrode assemblies being welded together to form a solder mark, wherein a first tape covers the solder mark.

[0007] In some embodiments, the thickness of the first tape is h1, the thickness of the reinforcing layer is h2, and the value of h1 / h2 ranges from 2 to 10.

[0008] In some embodiments, the two sets of electrode assemblies each include a negative electrode sheet, the negative electrode sheet includes a negative active material layer and a negative current collector, the negative current collector includes an uncoated area of ​​the active material layer not covered by the negative active material layer, the uncoated area of ​​the active material layer includes a negative electrode tab, and the thickness of the negative current collector is less than or equal to 5.5 μm.

[0009] In some embodiments, the secondary battery further includes a second tape, wherein the cover assembly further includes a negative electrode post connected to the adapter plate, the negative electrode post being welded to the adapter plate to form a solder mark, and the second tape covering the solder mark and at least a portion of the first tape.

[0010] In some embodiments, the reinforcing layer is located on the opposite surface of the negative electrode tab along its thickness direction.

[0011] In some embodiments, the secondary battery further includes a third tape disposed on the outer side of the negative electrode tab of each electrode assembly facing the outer casing, wherein the orthogonal projection of the reinforcing layer on the outer side of the negative electrode tab is completely within the third tape in the thickness direction of each electrode assembly.

[0012] In some embodiments, the adhesion between the first tape and the reinforcing layer is greater than the adhesion between the reinforcing layer and the negative electrode tab.

[0013] An embodiment of this utility model also provides an electronic device that includes the aforementioned secondary battery.

[0014] The technical solution of this utility model effectively prevents the negative electrode tab from wrinkling by setting an insulating layer at the negative electrode tab. Furthermore, covering the reinforcing layer with a first adhesive tape prevents the reinforcing layer from detaching and affecting battery performance, such as preventing electrolyte contamination. The synergistic effect of the first adhesive tape and the reinforcing layer also improves the support for the negative electrode tab, preventing the tab from being inserted into or torn. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A perspective view of a secondary battery according to an embodiment of the present invention is shown.

[0017] Figure 2A A cross-sectional schematic diagram of a secondary battery according to an embodiment of the present invention is shown.

[0018] Figure 2B This is a schematic diagram of the tabs, adapters, and posts of two electrode assemblies welded together according to some embodiments.

[0019] Figure 3 yes Figure 2A A cross-sectional schematic diagram of the electrode assembly of the secondary battery.

[0020] Figures 4A to 4D This is a schematic diagram illustrating different manufacturing stages of a negative electrode sheet according to an embodiment of the present invention.

[0021] Figure 4E yes Figure 4D A cross-sectional schematic diagram.

[0022] Figure 5 This is a schematic diagram of the negative electrode sheet after the negative electrode tab has been cut, according to some other embodiments.

[0023] Figure 6 This is a schematic diagram showing the first tape adhered to each electrode assembly according to some embodiments.

[0024] Figure 7 This is a schematic diagram of bonding a first tape and a second tape to each set of electrode assemblies according to some other embodiments.

[0025] Figure 8 This is a cross-sectional schematic diagram of a secondary battery according to some other embodiments.

[0026] Figure 9 A schematic diagram of the electronic device according to an embodiment of the present invention is shown when it is a vehicle. Detailed Implementation

[0027] To better understand the spirit of the embodiments of this utility model, the following description is based on some preferred embodiments of this utility model.

[0028] Embodiments of this utility model will be described in detail below. Throughout this specification, identical or similar components and components having identical or similar functions are indicated by similar reference numerals. The embodiments described herein with reference to the accompanying drawings are illustrative, diagrammatic, and intended to provide a basic understanding of the utility model. The embodiments of this utility model should not be construed as limiting the utility model.

[0029] As used herein, the terms “approximately,” “generally,” “substantially,” and “about” are used to describe and indicate minor variations. When used in conjunction with an event or situation, these terms may refer to examples in which the event or situation occurred precisely or in examples in which the event or situation occurred very approximately.

[0030] In this specification, unless otherwise specified or limited, relative terms such as “central,” “longitudinal,” “lateral,” “front,” “rear,” “right,” “left,” “inner,” “outer,” “lower,” “higher,” “horizontal,” “vertical,” “above,” “below,” “above,” “below,” “top,” “bottom,” and their derivatives (e.g., “horizontally,” “downward,” “upward,” etc.) should be interpreted as referring to the directions described in the discussion or depicted in the drawings. These relative terms are used for descriptive convenience only and do not require that the present invention be constructed or operated in a particular orientation.

[0031] For ease of description, "first," "second," "third," etc., can be used in this article to distinguish different components of a figure or a series of figures. "First," "second," "third," etc., are not intended to describe the corresponding components.

[0032] Figure 1 A perspective view of a secondary battery according to an embodiment of the present invention is shown. Figure 2A A cross-sectional schematic diagram of a secondary battery according to an embodiment of the present invention is shown. Figure 2B This is a schematic diagram of the tabs, adapters, and posts of two electrode assemblies welded together according to some embodiments. Figure 3 yes Figure 2A A cross-sectional schematic diagram of the electrode assembly of the secondary battery. It should be understood that... Figures 1 to 3 The secondary battery described herein is illustrated using a prismatic battery as an example. However, the secondary battery of this invention can also be any other suitable type of secondary battery, such as a pouch battery or a cylindrical battery.

[0033] Combination Figures 1 to 3 As shown, the secondary battery 100 may include a housing 200, which includes a peripheral sidewall 109 and an end wall 111 connected to one end of the peripheral sidewall 109. An opening 205 is provided at the other end of the peripheral sidewall 109 opposite to the end wall 111. A cover assembly 221 covers the opening 205 of the housing 200 to define a receiving cavity together with the housing 200. Two sets of electrode assemblies 140 are disposed opposite each other in the receiving cavity along the thickness direction of each set of electrode assemblies 140. The material of the housing 200 may be, for example, an aluminum shell, a steel shell, or a flexible shell.

[0034] The direction from end wall 111 to cover assembly 221 is the height direction Z of secondary battery 100. Height direction Z can correspond to direction D1 described below. In this embodiment, the two sets of electrode assemblies 140 are stacked in the housing 200 along the thickness direction of the two sets of electrode assemblies 140.

[0035] In some embodiments, the two sets of electrode assemblies 140 include two electrode assemblies 120. See also Figure 3 As shown, each electrode assembly 120 is a wound body formed by winding a negative electrode 101, a positive electrode 102, and a separator 204 located between the negative electrode 101 and the positive electrode 102. In other embodiments, the electrode assembly 120 may also be a stacked body formed by sequentially stacking the negative electrode 101, the positive electrode 102, and the separator 204 located between the negative electrode 101 and the positive electrode 102. The electrode assembly 120 may be flat. Correspondingly, the housing 200 may be flat and have a cuboid shape. The plurality of negative electrode tabs 150 of the negative electrode 101 and the plurality of positive electrode tabs 151 of the positive electrode 102 may be stacked in the thickness direction of the electrode assembly 120, respectively. The negative electrode 101, the positive electrode 102, and the separator are formed into the electrode assembly 120 by winding or stacking, and then the electrode assembly 120 is sealed in the housing to form a secondary battery.

[0036] The positive electrode may include a positive current collector and a positive active material layer, the positive active material layer being coated on a portion of the surface of the positive current collector. The negative electrode may include a negative current collector and a negative active material layer, the negative active material layer being coated on a portion of the surface of the negative current collector. In some embodiments, such as in a lithium-ion battery, the material of the positive current collector may be aluminum. The positive active material layer may include a positive active material, such as lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. For high-nickel ternary lithium batteries, the positive active material may be a ternary material composed of nickel, cobalt, and manganese (or aluminum). The material of the negative current collector may be copper. The negative active material layer may include a negative active material, such as carbon or silicon. The separator material may be, for example, PP (polypropylene) or PE (polyethylene).

[0037] The outer casing 200 also contains an electrolyte, which serves to conduct ions between the positive and negative electrodes. In one embodiment of this invention, the electrolyte includes, for example, an organic solvent and a lithium salt. The organic solvent is selected from one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl acetate (EA), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), or diethyl carbonate (DEC). The lithium salt is selected from one or more of lithium bis(fluorosulfonyl)imide (LiFSi), lithium difluorophosphate (LiPO2F2), lithium hexafluorophosphate (LiPF6), or lithium tetrafluoroborate (LiBF4). In one embodiment of this invention, the lithium salt is selected, for example, from lithium hexafluorophosphate, and the organic solvent is selected, for example, from a mixture of ethylene carbonate, methyl ethyl carbonate, diethyl carbonate, and propylene carbonate. Ethyl carbonate, methyl ethyl carbonate, diethyl carbonate, and propylene carbonate are mixed, for example, in a volume ratio of 1:1:1:1. In an argon-atmosphere glove box with a water content of less than 10 ppm, thoroughly dried LiPF6 is dissolved in the mixed organic solvent and mixed thoroughly to obtain an electrolyte. The concentration of LiPF6 is, for example, 1 mol / L.

[0038] Combination Figures 1 to 3As shown, the negative terminal 223 and the positive terminal 224 are disposed on the cover plate assembly 221. The negative terminal 223 and the positive terminal 224 can pass through the cover plate assembly 221 and are insulated from the cover plate assembly 221. Each group of electrode assemblies 140 is provided with a negative terminal tab 150 and a positive terminal tab 151 at one end facing the cover plate assembly 221. In this embodiment, the negative terminal tab 150 and the positive terminal tab 151 of each group of electrode assemblies 140 are respectively connected to the corresponding negative terminal 223 and the positive terminal 224. The cover plate assembly 221 may include an adapter piece 226. The negative terminal 223 and the positive terminal 224 and the corresponding adapter piece 226 may be integral, or the negative terminal 223 and the positive terminal 224 and the corresponding adapter piece 226 may be separate. In some embodiments, the negative electrode tab 150 and the negative electrode post 223, and the positive electrode tab 151 and the positive electrode post 224, can be connected via corresponding adapter pieces 226. The negative electrode tab 150 and the positive electrode tab 151 can be bent and soldered to the adapter piece 226, thereby forming solder marks 107 and 108 on the negative electrode tab 150 and the positive electrode tab 151, respectively. The negative electrode tab 150 and the positive electrode tab 151 can be soldered to the adapter piece 226 after (e.g.) Figure 2B (As shown), then fold the two sets of electrode components 140 toward each other, and then install them into the housing 200 (as shown). Figure 2A (As shown).

[0039] Specifically, the negative electrode tab 150 includes an uncoated area of ​​the active material layer of the negative electrode current collector (uncoated area 110e of the active material layer as described below). The uncoated area of ​​the active material layer may include a bending portion 1501 and a connecting portion 1502. The connecting portion 1502 can be fixedly connected to the cover plate assembly 221 via an adapter piece 226. The bending portion 1501 is connected between the electrode body of the negative electrode sheet 101 and the connecting portion 1502. The adapter piece 226 is welded to the bent connecting portion 1502, and the solder mark 107 is located on the connecting portion 1502.

[0040] Figures 4A to 4D This is a schematic diagram illustrating different manufacturing stages of a negative electrode sheet according to an embodiment of the present invention. First, see... Figure 4A As shown, a negative electrode active material layer 130 is coated on both opposite surfaces of the negative electrode current collector 110 along its thickness direction. The negative electrode active material layer 130 can be applied to the negative electrode current collector 110 using a coating device. The negative electrode current collector 110 includes an active material layer coated area 110f covered by the negative electrode active material layer 130, and an active material layer uncoated area 110e not covered by the negative electrode active material layer 130. The edge portion of the negative electrode current collector 110 in the width direction is not coated with the negative electrode active material layer 130, forming the active material layer uncoated area 110e. In some embodiments, the material of the negative electrode current collector 110 can be, for example, copper.

[0041] See Figure 4B As shown, a reinforcing layer 190 is applied, which covers a portion of the uncoated area 110e of the active material layer. In some embodiments, the negative electrode active material layer 130 and the reinforcing layer 190 may be applied simultaneously.

[0042] After applying the negative electrode active material layer 130 and the reinforcing layer 190, the negative electrode current collector 110 and the negative electrode active material layer 130 can be cut along the dotted line L1 to obtain... Figure 4C The diagram shows a single negative electrode 101 for forming a single electrode assembly. The uncoated area 110e of the active material layer of the negative current collector 110 of the negative electrode 101 can then be cut; this cutting process can be referred to as tab cutting. In some embodiments, a laser can be used to perform the tab cutting process.

[0043] After cutting, see Figure 4D and Figure 4E As shown, where Figure 4E yes Figure 4D A cross-sectional schematic diagram shows a plurality of negative electrode tabs 150 spaced apart along the length direction (direction D2) of the negative electrode sheet 101. The uncut portion of the negative electrode current collector 110 and the negative electrode active material layer 130 can be referred to as the electrode body 160. The negative electrode tabs 150 extend from the first edge 160e of the electrode body 160 along direction D1 (which can be referred to as the first direction). The uncoated area 110e of the active material layer includes the negative electrode tabs 150. Direction D1 can correspond to the aforementioned height direction Z of the secondary battery 100. In this embodiment, a portion of the reinforcing layer 190 is located on the negative electrode tabs 150.

[0044] refer to Figure 4E The electrode body 160 may include a negative electrode current collector 110 and a negative electrode active material layer 130, wherein the negative electrode active material layer 130 covers two opposing surfaces 1101 and 1102 of the negative electrode current collector 110 along its thickness direction. In other embodiments, the negative electrode active material layer 130 may be disposed on either of the two surfaces 1101 and 1102. Furthermore, a thinning region 130e is formed at the edge of the negative electrode active material layer 130 along direction D1, and the thinning region 130e is connected to a uniformly coated straight region 130b of the negative electrode active material layer 130. The thickness of the thinning region 130e gradually decreases along direction D1. In some embodiments, a reinforcing layer 190 is located on the two surfaces 1101 and 1102 of the negative electrode current collector 110.

[0045] This utility model is illustrated by taking the current collector coated with active material and cut to form an electrode tab. The electrode tab involved in this utility model can also be connected to the electrode body 160 by other means such as welding.

[0046] To address the issue of wrinkling at the negative electrode tab 150, a reinforcing layer 190 is incorporated at the negative electrode tab 150. This reinforcing layer 190 provides support for the tab and effectively prevents wrinkling. Furthermore, the reinforcing layer 190 at the negative electrode tab 150 prevents unwanted short circuits, thus enhancing battery safety.

[0047] The reinforcing layer 190 is spaced apart from the negative electrode active material layer 130 by a preset spacing G in direction D1. By setting the preset spacing G, bulging of the negative electrode active material layer 130 and / or the reinforcing layer 190 can be avoided. In some embodiments, considering process capability, the preset spacing G can range from 0.1mm to 1.1mm, for example, it can be 0.1mm to 1mm, or 0.1mm to 0.5mm. If the size of the preset spacing G is too small, mutual dissolution and bulging are likely to occur; if the size of the spacing G is too large, wrinkling of the negative electrode tab cannot be effectively prevented.

[0048] See again Figure 4D As shown, the negative electrode tab 150 is connected to the first edge 160e of the electrode body 160, and the first edge 160e extends along a direction D2 (which can be called the second direction) perpendicular to the direction D1. The direction D2 can be the width direction of the negative electrode tab 150, and the width of each negative electrode tab 150 can decrease as the distance from the electrode body 160 increases.

[0049] In this embodiment, during the tab cutting process, only the area covered by the reinforcing layer 190 is cut, so that the reinforcing layer 190 is located in the uncoated area 110e of the active material layer in the electrode body 160, and also on the uncoated area 110e of the active material layer in the negative electrode tab 150. A transition region 153 is provided between the negative electrode tab 150 and the active material layer coated area 110f, and the reinforcing layer 190 is located on part of the transition region 153 and part of the surface of the negative electrode tab 150.

[0050] Figure 5 This is a schematic diagram of the negative electrode sheet after the negative electrode tab has been cut, according to some other embodiments. Figure 5 Several aspects of the illustrated embodiments are related to the above references. Figures 4A to 4E Similar to the descriptions below, the main focus is on... Figure 5 The differences between the illustrated embodiments are as follows. See also: Figure 5As shown, in this embodiment, the reinforcing layer 190 is entirely located on the negative electrode tab 150. A portion of the negative electrode active material layer 130 extends onto the negative electrode tab 150. The bottom edge of the reinforcing layer 190 adjacent to the negative electrode active material layer 130 is located on the negative electrode tab 150. In this structure of the negative electrode sheet 101, since the areas covered by both the reinforcing layer 190 and the negative electrode active material layer 130 are cut, the area of ​​the negative electrode active material layer 130 in the electrode body 160 can be increased, thereby increasing the battery energy density. Furthermore, the negative electrode active material layer 130 and the reinforcing layer 190 on the negative electrode tab 150 can work together to provide support for the negative electrode tab, thus improving the tab support capability.

[0051] Figure 6 This is a schematic diagram showing the first adhesive tape bonded to each electrode assembly according to some embodiments. (In conjunction with...) Figures 2A-2B , Figures 4A to 6 As shown, the first adhesive tape 300 is disposed on the inner side of the negative electrode tab 150 away from the outer casing 200. The negative electrode tab 150 is an integral structure composed of multiple negative electrode tabs, and the inner side refers to the inner side of the innermost negative electrode tab 150 away from the outer casing 200. In the thickness direction of each electrode assembly 140, the orthogonal projection of the reinforcing layer 190 lies entirely within the first adhesive tape 300. That is, the orthogonal projection area of ​​the first adhesive tape 300 is larger than the orthogonal projection area of ​​the reinforcing layer 190. The first adhesive tape 300 may or may not contact the reinforcing layer 190. By providing the first adhesive tape 300 and ensuring that the orthogonal projection of the reinforcing layer 190 lies entirely within it, the reinforcing layer can be prevented from detaching, thus avoiding impact on battery performance. For example, the reinforcing layer may detach due to relative bending during welding of the negative electrode tabs. Furthermore, if the reinforcing layer detaches and falls into the electrolyte, it will cause electrolyte contamination. By setting a first adhesive tape 300 with a projected area larger than that of the reinforcing layer 190, electrolyte contamination caused by the reinforcing layer falling off can be avoided. The first adhesive tape 300 and the reinforcing layer 190 work together to improve the support for the negative electrode tab, preventing the tab from being inserted into or torn.

[0052] In some embodiments, the first adhesive tape 300 can be bonded to the reinforcing layer 190. In some embodiments, the adhesive force between the first adhesive tape 300 and the reinforcing layer 190 is greater than the adhesive force between the reinforcing layer 190 and the negative electrode tab 150. Thus, even when the reinforcing layer 190 and the negative electrode tab 150 are not bonded, the first adhesive tape 300 can still maintain its adhesive force, thereby more effectively preventing the reinforcing layer from falling off.

[0053] To accommodate high-capacity battery cells, more layers of uncoated active material are required. During laser welding of these multiple layers of uncoated active material to the adapter plate, the outer layers need to be bent due to the presence of these layers, resulting in a longer path for the uncoated active material. This makes the uncoated active material more prone to wrinkling. In some embodiments requiring more layers of uncoated active material, the negative electrode tab 150 has a height of 35mm-38mm along direction D1, which is higher than the conventional tab height (typically 30mm-32mm), thus providing a longer tab path. However, the height of the uncoated active material area 110e corresponding to the higher tab is also greater, making it more prone to wrinkling. By setting a reinforcing layer 190 at the negative electrode tab 150 and covering the reinforcing layer 190 with a first adhesive tape 300, the support force of the negative electrode tab can be effectively improved, wrinkling of the uncoated area 110e of the active material layer in the multi-layer tab can be prevented, and the reinforcing layer can be prevented from falling off and affecting the battery performance.

[0054] In some embodiments, each electrode assembly 140 includes two electrode assemblies 120, with their positive electrode tabs 151 welded together and their negative electrode tabs 150 welded together. The positive and negative electrode tabs 151 of the two electrode assemblies 120 in each electrode assembly 140 are welded correspondingly and then welded to the adapter piece 226 before the two electrode assemblies 140 are bent relative to each other. The solder mark 107 formed by the welding of the negative electrode tab 150 is covered by a first adhesive tape 300. The first adhesive tape 300 protects the solder mark 107. Additionally, adhesive tape 400 can be applied to the positive electrode tab 151 to protect the solder mark 108 on the positive electrode tab 151.

[0055] The inclusion of two electrode assemblies in each electrode assembly 140 is merely an example; in other embodiments, each electrode assembly 140 may also include other numbers of electrode assemblies. For example, each electrode assembly 140 may include one or three electrode assemblies.

[0056] The thickness of the first adhesive tape 300 is h1, and the thickness of the reinforcing layer 190 is h2. The thickness h2 of the reinforcing layer 190 is the thickness of the reinforcing layer 190 on one surface of the negative electrode current collector 110. In some embodiments, the value range of h1 / h2 is 2-10. This range of values ​​for the thickness h1 of the first adhesive tape 300 and the thickness h2 of the reinforcing layer 190 provides a suitable ratio range, which can prevent the electrode tab from being inserted and improve the support force on the electrode tab.

[0057] Specifically, in some embodiments, the first adhesive tape 300 includes a first adhesive region 301, a second adhesive region 302, and a non-adhesive region 303, with the non-adhesive region 303 located between the first adhesive region 301 and the second adhesive region 302. In some embodiments, the first adhesive tape 300 may include a base layer and an adhesive layer, with the adhesive layer disposed in the first adhesive region 301 and the second adhesive region 302 to provide adhesion between them. The non-adhesive region 303 may only have a base layer without an adhesive layer. The first adhesive region 301 covers the main body of the electrode assembly, and the second adhesive region 302 covers the connecting portion 1502. In this embodiment, in the thickness direction of each set of electrode assemblies 140, the orthographic projection of the reinforcing layer 190 on the bent portion 1501 lies entirely within the non-adhesive region 303. Specifically, in the thickness direction of each set of electrode assemblies 140, the width of the orthographic projection of the non-adhesive region 303 is greater than the width of the orthographic projection of the reinforcing layer 190. The non-adhesive region 303 may or may not be in contact with the reinforcing layer 190. By ensuring that the orthographic projection of the reinforcing layer 190 is entirely within the non-adhesive region 303, the adhesive region can be prevented from pulling on the tabs, the reinforcing layer 190 can be prevented from being adhered to by the adhesive region and falling off, and the reinforcing layer can be protected to prevent the tabs from being inserted into the substrate.

[0058] In some embodiments, the material of the reinforcing layer 190 may include ceramic (boehmite), an aqueous binder, and a colorant. The aqueous binder may be, for example, a water-soluble polymer PAA (polyarylacetylene). If an oil-based binder is used in the reinforcing layer 190, an organic gas recovery system is required in the negative electrode production line. By using an aqueous binder, the negative electrode production line can eliminate the need for an organic gas recovery system. In some embodiments, the peel force between the reinforcing layer 190 using an aqueous binder and the negative electrode current collector 110 is >300 N / m. Furthermore, the ceramic design can also provide support for the reinforcing layer 190. In some embodiments, the volume percentage of ceramic (boehmite) in the reinforcing layer 190 is, for example, 10%-20%, the volume percentage of the aqueous binder is, for example, 75%-90%, and the volume percentage of the colorant (such as carbon black) is, for example, 0.5%-5%.

[0059] In some embodiments, the grayscale value of the reinforcing layer 190 is 0-110. In some embodiments, the material of the reinforcing layer 190 may include a color developer, such that the grayscale value of the reinforcing layer 190 is 0-100. In some embodiments, the color developer may be carbon black. If the reinforcing layer 190 does not contain a color developer, the reinforcing layer 190 will be a light color (e.g., white) with a high grayscale value. This will result in a small recognizable color difference between the color of the negative electrode current collector 110 (e.g., copper) and the white of the reinforcing layer 190, making it difficult for image recognition devices (e.g., CCD cameras) to recognize, thus causing problems such as image recognition issues. In embodiments where the reinforcing layer 190 contains a color developer, the grayscale value of the reinforcing layer 190 is 0-100, thereby solving the problem of difficulty in recognition by image recognition devices and facilitating the recognition of the size and position of the reinforcing layer 190 by CCD cameras. In addition, compared to a white reinforcing layer 190, by selecting a reinforcing layer 190 containing a color developer (e.g., carbon black), the reinforcing layer 190 can absorb more energy, thus reducing the power of the laser used in the tab cutting process. In the process of cutting tabs using variable power lasers, the power of the laser can also be reduced.

[0060] Figure 7 This is a schematic diagram showing the bonding of a first adhesive tape and a second adhesive tape to each electrode assembly according to some other embodiments. See also Figure 7 In some embodiments, a second adhesive tape may also be provided, which may be located in the area indicated by the dashed box As. The material of the second adhesive tape may be, for example, PET. In some embodiments, the thickness of the second adhesive tape may be, for example, 130 μm. The second adhesive tape may cover at least a portion of the first adhesive tape 300. The second adhesive tape may also cover the solder joint formed when the adapter 226 is soldered to the negative electrode post 223. The second adhesive tape can prevent particles from the solder joint of the adapter 226 and the negative electrode post 223 from falling into the electrode assembly.

[0061] In some embodiments, the thickness of the negative electrode current collector 110 is less than or equal to 5.5 μm (≤5.5 μm). A negative electrode current collector 110 with a thickness ≤5.5 μm can improve energy density to meet requirements such as fast charging. However, such a thin current collector makes the uncoated area 110e of the active material layer thinner and more prone to wrinkling. By providing the first adhesive tape 300 and combining it with the second adhesive tape, wrinkling of the uncoated area 110e of the active material layer of the thin current collector can be avoided, and the insertion of the electrode tab can be further avoided, improving the support force for the electrode tab.

[0062] Figure 8 This is a cross-sectional schematic diagram of a secondary battery according to some other embodiments. See also Figure 8As shown, a third adhesive tape 350 can also be provided, which is at least provided on the outer side of the negative electrode tab 150 of each electrode assembly 140 facing the housing 200. In the thickness direction of each electrode assembly 140, the orthogonal projection of the reinforcing layer 190 on the outer side of the negative electrode tab 150 can be completely located within the third adhesive tape 350. By providing the third adhesive tape 350, the reinforcing layer can be prevented from detaching, thus avoiding impact on battery performance.

[0063] In some embodiments, similar to the first adhesive tape 300, the third adhesive tape 350 may include a first adhesive region, a second adhesive region, and a non-adhesive region located between the first and second adhesive regions. In the thickness direction of each electrode assembly 140, the orthogonal projection of the reinforcing layer 190 at the outer side of the negative electrode tab 150 may lie entirely within the third adhesive tape 350. Covering the reinforcing layer 190 with the non-adhesive region prevents the tape from pulling on the tab, prevents the reinforcing layer 190 from being adhered to by the tape and detaching, and provides protection for the reinforcing layer.

[0064] Figure 9 A schematic diagram is shown when the electronic device according to an embodiment of this utility model is a vehicle. See also Figure 9This utility model also provides an electronic device 1000. For ease of explanation, the following embodiments use a vehicle as an example. A battery pack 1002 is installed inside the vehicle. The battery pack 1002 can be located at the bottom, head, or tail of the vehicle body 1001. The battery pack 1002 can be used to power the vehicle; for example, it can serve as the vehicle's operating power source. The working part of the electronic device 1000 is electrically connected to the battery pack 1002 to obtain electrical power. The vehicle can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, but are not limited thereto. The working part is the vehicle body, and the battery pack 1002 is located at the bottom of the vehicle body, providing electrical power for the vehicle's movement or the operation of its internal electrical components. However, in other embodiments, the electronic device 1000 can also be a mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, power tool, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; the working unit can obtain electrical energy from the battery pack 1002 and perform corresponding work, such as the fan blade rotation unit of a fan, the vacuuming unit of a vacuum cleaner, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This utility model embodiment does not impose any special limitations on the above-mentioned electronic device 1000. The battery pack 1002 may include multiple secondary batteries, such as the secondary battery 100 described above.

[0065] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A secondary battery, characterized in that, include: The outer shell defines the receiving cavity; Cover plate assembly for sealing the housing; Two sets of electrode assemblies are disposed opposite to each other in the receiving cavity along the thickness direction of each set of electrode assemblies. The cover plate assembly includes an adapter piece. The two sets of electrode assemblies each include a main body and a negative electrode tab extending from the main body. The negative electrode tab is electrically connected to the adapter piece. The first tape is disposed on the inner side of the negative electrode tab opposite to the outer shell; A reinforcing layer, at least a portion of which is located on the negative electrode tab, wherein, in the thickness direction of each electrode assembly, the orthogonal projection of the reinforcing layer lies entirely within the first tape.

2. The secondary battery according to claim 1, characterized in that, The negative electrode tab includes a bent portion and a connecting portion. The connecting portion is connected to the adapter piece. The bent portion is connected between the main body and the connecting portion. The reinforcing layer is located in the bent portion. The first tape includes a first adhesive region, a second adhesive region, and a non-adhesive region located between the first adhesive region and the second adhesive region. The first adhesive region covers the main body, and the second adhesive region covers the connecting portion. In the thickness direction of each electrode assembly, the orthographic projection of the reinforcing layer lies entirely within the non-adhesive region.

3. The secondary battery according to claim 1, characterized in that, Each electrode assembly includes two electrode assemblies, the negative electrode tabs of the two electrode assemblies being welded together to form a solder mark, wherein the first tape covers the solder mark.

4. The secondary battery according to claim 1, characterized in that, The thickness of the first tape is h1, the thickness of the reinforcing layer is h2, and the value of h1 / h2 ranges from 2 to 10.

5. The secondary battery according to claim 1, characterized in that, The two sets of electrode assemblies each include a negative electrode sheet, which comprises a negative electrode active material layer and a negative electrode current collector. The negative electrode current collector includes an uncoated area of ​​the active material layer not covered by the negative electrode active material layer, and the uncoated area of ​​the active material layer includes the negative electrode tab. The thickness of the negative electrode current collector is less than or equal to 5.5 μm.

6. The secondary battery according to claim 1, characterized in that, Also includes: Second tape; The cover plate assembly further includes a negative terminal connected to the adapter piece, the negative terminal being welded to the adapter piece to form a solder mark, and the second tape covering the solder mark and at least a portion of the first tape.

7. The secondary battery according to claim 1, characterized in that, The reinforcing layer is located on the opposite surface of the negative electrode tab along its thickness direction.

8. The secondary battery according to claim 7, characterized in that, Also includes: A third tape is disposed on the outer side of the negative electrode tab of each electrode assembly facing the housing, wherein the orthogonal projection of the reinforcing layer on the outer side of the negative electrode tab is completely located within the third tape in the thickness direction of each electrode assembly.

9. The secondary battery according to claim 1, characterized in that, The adhesion between the first tape and the reinforcing layer is greater than the adhesion between the reinforcing layer and the negative electrode tab.

10. An electronic device, characterized in that, Includes the secondary battery as described in any one of claims 1-9.

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