Secondary battery, battery pack, and electronic device
By setting a reinforcing layer and an appropriate spacing in the uncoated area of the active material layer of the negative electrode current collector, the problem of wrinkling in the uncoated area of the active material layer of the negative electrode sheet is solved, thereby improving the safety and fast charging capability of the battery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ENVISION AESC JAPAN LTD
- Filing Date
- 2025-05-13
- Publication Date
- 2026-06-12
AI Technical Summary
The uncoated areas of the active material layer on the existing negative electrode are prone to wrinkling, leading to problems such as edge bulging and short circuits during the manufacturing process of secondary batteries.
A reinforcing layer is set in the uncoated area of the active material layer of the negative electrode current collector, and a preset gap of 0.1mm-1.1mm is set between the reinforcing layer and the active material layer to ensure that the reinforcing layer and the active material layer are immiscible. At the same time, the ratio of the maximum width of the uncoated area of the active material layer to the gap is controlled within the range of 22-400.
It effectively prevents wrinkling in uncoated areas of the active material layer, avoids mutual dissolution between the reinforcing layer and the active material layer, improves battery safety, reduces DC internal resistance, and enhances the battery's fast charging capability.
Smart Images
Figure CN224355252U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of battery technology, and more specifically, to a secondary battery, battery pack, and electronic device. Background Technology
[0002] In the field of new energy power batteries, the application of rechargeable batteries is becoming increasingly widespread. For example, rechargeable batteries (such as lithium-ion batteries) can be used in electronic devices such as vehicles, energy storage, mobile phones, tablets, wearable devices, power banks, e-cigarettes, digital products, power tools, power units, and energy storage devices. One type of rechargeable battery is the prismatic battery, which includes a casing and an electrode assembly. The electrode assembly includes 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 within the casing.
[0003] The existing negative electrode sheet only has a negative electrode active material layer on the negative electrode current collector. The negative electrode active material layer is directly adjacent to the uncoated area of the active material layer of the negative electrode current collector, which causes the uncoated area of the active material layer to wrinkle easily, and this problem urgently needs to be solved. Utility Model Content
[0004] In view of the problems existing in the related technologies, the purpose of this application is to provide a secondary battery, battery pack and electronic device that can at least avoid the mutual dissolution and bulging of the reinforcing layer and the negative electrode active material layer, and can effectively prevent wrinkling of the uncoated area of the active material layer of the negative electrode current collector.
[0005] To achieve the above objectives, embodiments of this application provide a secondary battery comprising an electrode assembly, the electrode assembly including a negative electrode, a positive electrode, and a separator disposed between the negative electrode and the positive electrode. The negative electrode includes a negative active material layer and a negative current collector. The negative current collector includes an active material layer coated area covered on at least one side by the negative active material layer and an active material layer uncoated area not covered by the negative active material layer. The active material layer coated area and the active material layer uncoated area are disposed adjacent to each other along a predetermined direction, wherein the maximum width of the active material layer uncoated area in the predetermined direction is W1. A reinforcing layer covers a portion of the active material layer uncoated area. In the predetermined direction, the reinforcing layer and the negative active material layer have a predetermined spacing G, wherein the value of G ranges from 0.1 mm to 1.1 mm, and the value of W1 / G ranges from 22 to 400.
[0006] In some embodiments, the uncoated area of the active material layer includes tabs, a transition region is provided between the tabs and the coated area of the active material layer, and a reinforcing layer is located on the surface of a portion of the transition region and a portion of the tabs.
[0007] In some embodiments, the uncoated area of the active material layer includes tabs, and a portion of the negative electrode active material layer is disposed on the surface of a portion of the tabs along a predetermined direction.
[0008] In some embodiments, the negative electrode current collector has two surfaces opposite each other along its thickness direction, the reinforcing layer on either surface has a maximum thickness T1, the negative electrode active material layer on either surface has a maximum thickness T2, and the value of T1 / T2 ranges from 0.1 to 0.5.
[0009] In some embodiments, the maximum width of the reinforcing layer in a preset direction is W2, and the value of W1 / W2 ranges from 25 to 7.5.
[0010] In some embodiments, a negative electrode, a positive electrode, and a separator are sequentially stacked and wound to form an electrode assembly. The number of turns of the negative electrode is n, the number of tabs is N, and the value of N / n ranges from 1.1 to 2.
[0011] In some embodiments, the grayscale value of the reinforcing layer is 0-110. In some embodiments, the thickness of the negative electrode current collector is less than or equal to 5.5 μm.
[0012] In some embodiments, the secondary battery is a prismatic battery, and the secondary battery further includes: a housing having an opening, an electrode assembly disposed within the housing; a cover plate assembly sealing the opening of the housing; an electrode post passing through the cover plate assembly and electrically isolated from the cover plate assembly; and an adapter piece disposed on the side of the cover plate facing the electrode assembly and electrically connecting the electrode post to the electrode assembly, wherein the uncoated area of the active material layer includes a bend and a connection, the bend being connected between the coated area of the active material layer and the connection; a reinforcing layer is located at the bend, and the adapter piece is welded to the connection.
[0013] Embodiments of this application also provide a battery pack comprising any of the aforementioned secondary batteries.
[0014] Embodiments of this application also provide an electronic device that includes the battery pack described above.
[0015] The technical solution of this application effectively prevents wrinkling in the uncoated areas of the active material layer of the negative electrode current collector by setting a reinforcing layer thereon. Furthermore, the preset spacing G between the reinforcing layer and the negative electrode active material layer is set to a range of 0.1mm-1.1mm, which avoids mutual dissolution and bulging between the reinforcing layer and the negative electrode active material layer, and effectively prevents wrinkling in the uncoated areas of the active material layer. In addition, the ratio of the maximum width W1 of the uncoated area of the active material layer to the preset spacing G is set to a range of 22-400. This allows for a suitable preset spacing G within a suitable maximum width W1 range, preventing the reinforcing layer and the negative electrode active material layer from fusing due to an excessively small preset spacing G, and avoiding bulging caused by fusing, thus preventing fusion dislocations. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of this application 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 application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 A perspective view of a secondary battery according to an embodiment of this application is shown.
[0018] Figure 2A A cross-sectional schematic diagram of a secondary battery according to an embodiment of this application is shown.
[0019] Figure 2B This is a schematic diagram of the tabs, adapters, and posts of two electrode assemblies welded together according to some embodiments.
[0020] Figure 3 yes Figure 2A A cross-sectional schematic diagram of the electrode assembly of the secondary battery.
[0021] Figures 4A to 4D This is a schematic diagram illustrating different manufacturing stages of a negative electrode sheet according to an embodiment of this application.
[0022] Figure 4E yes Figure 4D The diagram shows a cross-sectional view of the negative electrode plate.
[0023] Figure 5 According to some embodiments Figure 4D A magnified view of region A1 in the diagram.
[0024] Figure 6A This is a schematic diagram of the negative electrode sheet after the negative electrode tab has been cut, according to some other embodiments.
[0025] Figure 6B According to other embodiments, corresponding to Figure 6A A magnified view of region A2 in the diagram.
[0026] Figure 7 A schematic diagram is shown when the electronic device according to an embodiment of this application is a vehicle. Detailed Implementation
[0027] To better understand the spirit of the embodiments of this application, the following description is based on some preferred embodiments of this application.
[0028] Embodiments of this application 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 and diagrammatic in nature and are intended to provide a basic understanding of this application. The embodiments of this application should not be construed as limiting this application.
[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 accompanying drawings. These relative terms are used for descriptive convenience only and do not require that this application be constructed or operated in a particular orientation.
[0031] For ease of description, the terms "first," "second," "third," etc., are used herein to distinguish different components of a figure or a series of figures. The terms "first," "second," "third," etc., are not intended to describe corresponding components. Furthermore, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.
[0032] Currently, the negative electrode current collector of the negative electrode sheet only has a layer of negative active material. This layer is directly adjacent to the uncoated area of the active material layer of the negative electrode current collector, which leads to the problem that the uncoated area of the active material layer is prone to wrinkling. For example, to match high-capacity cells, more layers of uncoated active material layers are needed. When laser welding these multiple layers of uncoated active material layers to the adapter plate, the outer uncoated active material layers need to be bent due to the presence of multiple layers, resulting in a longer path for the uncoated active material layers. This makes the uncoated active material layers even more prone to wrinkling.
[0033] Figure 1 A perspective view of a secondary battery according to an embodiment of this application is shown. Figure 2A A cross-sectional schematic diagram of a secondary battery according to an embodiment of this application is shown. Figure 2BThis 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.
[0034] Combination Figures 1 to 2B 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, in which the electrode assembly 120 is located.
[0035] The direction from end wall 111 to cover assembly 221 is the height direction Z of secondary battery 100. Height direction Z may correspond to direction D1 described below. In this embodiment, two electrode assemblies 120 are stacked in housing 200 along the thickness direction of electrode assembly 120. In other embodiments, more than two electrode assemblies 120 may be provided in housing 200.
[0036] In some embodiments, see Figure 3 As shown, the 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. The negative electrode 101, the positive electrode 102, and the separator are formed by winding or stacking to form the electrode assembly 120, and then the electrode assembly 120 is sealed in the housing to form a secondary battery.
[0037] 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).
[0038] Combination Figures 1 to 3 As shown, the negative electrode post 223 and the positive electrode post 224 are disposed on the cover plate assembly 221. The negative electrode post 223 and the positive electrode post 224 can pass through the cover plate assembly 221 and are insulated from the cover plate assembly 221. An electrode tab is provided at one end of the electrode assembly 120 facing the cover plate assembly 221. In this embodiment, the negative electrode tab 150 and the positive electrode tab 151 at one end of the electrode assembly 120 are respectively connected to the corresponding negative electrode post 223 and the positive electrode post 224. 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 by corresponding adapter pieces 226. The negative electrode tab 150 and the positive electrode tab 151 can be bent and welded to the adapter piece 226, thereby forming solder marks 107 and 108 respectively on the negative electrode tab 150 and the positive electrode tab 151. Negative electrode tab 150 and positive electrode tab 151 can be soldered to adapter piece 226 after (e.g.) Figure 2B (As shown), then fold the two electrode assemblies 120 toward each other, and then insert them into the housing 200 (as shown). Figure 2A (As shown).
[0039] 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 described below). The uncoated area of the active material layer may include a bent 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 bent portion 1501 is connected between the electrode body of the negative electrode sheet 101 and the connecting portion 1501. The adapter piece 226 is welded to the bent connecting portion 1502.
[0040] It should be understood that Figures 1 to 3The example used here is a prismatic battery. The secondary battery described in this application can also be any other suitable type, such as a pouch battery or a cylindrical battery.
[0041] Figures 4A to 4D This is a schematic diagram illustrating different manufacturing stages of a negative electrode sheet according to an embodiment of this application. 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.
[0042] 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.
[0043] 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.
[0044] 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 or a predetermined 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. Reference Figure 4EThe 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.
[0045] This application uses the example of forming an electrode tab after the current collector is coated with an active material and cut. The electrode tab involved in this application can also be connected to the electrode body 160 by other means such as welding.
[0046] To address the issue of wrinkling in the uncoated areas of the active material layer, a reinforcing layer 190 is provided at the uncoated areas 110e. This reinforcing layer 190 provides support to the uncoated areas 110e, effectively preventing wrinkling and allowing for more complex layers of the uncoated active material layer 110e. Furthermore, the reinforcing layer 190 prevents unwanted short circuits, thus enhancing battery safety.
[0047] 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.
[0048] Figure 5 According to some embodiments Figure 4D A magnified view of region A1 in the diagram. See also... Figure 5As shown, the maximum width of the uncoated area 110e of the active material layer in direction D1 is W1. In this embodiment, the maximum width W1 corresponds to the distance between the edge of the negative electrode tab 150 away from the negative electrode active material layer 130 and the negative electrode active material layer 130. In direction D2, the width of the uncoated area 110e of the active material layer is uniform (within the process tolerance range). The reinforcing layer 190 covers a portion of the uncoated area 110e of the active material layer, and the reinforcing layer 190 is spaced apart from the negative electrode active material layer 130 in direction D1 by a preset spacing G. In some embodiments, the value of W1 / G ranges from 22 to 400. In some embodiments, the value of G ranges from 0.1 mm to 1.1 mm. In some embodiments, considering process capability, the preset spacing G can, for example, range from 0.1 mm to 1 mm, or from 0.1 mm to 0.5 mm. If the preset spacing G is too small, mutual dissolution and bulging are likely to occur; if the preset spacing G is too large, it cannot effectively prevent wrinkling in the uncoated area of the active material layer.
[0049] The aforementioned range of values for the preset spacing G and the maximum width W1 takes into account both the uncoated area 110e of the active material layer (which can be referred to as the current collector blank) and the preset spacing G. This allows for a suitable preset spacing G within a suitable maximum width W1 range for the uncoated area 110e of the active material layer. This avoids the reinforcing layer 190 from fusing with the negative electrode active material layer 130 due to an excessively small preset spacing G, and also avoids issues such as bulging edges caused by fusing, thus preventing fusion dislocations.
[0050] Furthermore, the aforementioned setting of the maximum width W1 of the uncoated active material layer 110e in the secondary battery allows for a more likely occurrence of multiple uncoated active material layer regions 110e. Simultaneously, in the secondary battery, the reinforcing layer 190 provides support, preventing the intercalation of the uncoated active material layer 110e, thus improving battery safety, reducing DCR, and enhancing the battery's fast-charging capability.
[0051] In some embodiments, the thickness of the negative electrode current collector 110 is less than or equal to 5.5 μm. A negative electrode current collector 110 with a thickness of less than or equal to 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 a reinforcing layer 190 at the uncoated area 110e of the active material layer, and setting the preset spacing G to a range of 0.1 mm to 1.1 mm and the W1 / G range to 22 to 400, wrinkling of the thin uncoated area 110e of the active material layer can be effectively prevented, while also avoiding mutual dissolution and bulging between the reinforcing layer 190 and the negative electrode active material layer 130.
[0052] 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 on 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. The reinforcing layer 190 on the electrode body 160 also extends between the first edge 160e of the electrode body 160 and the negative active material layer 130. The reinforcing layer 190 on the negative electrode tab 150 can provide support for the negative electrode tab 150, and the reinforcing layer 190 on the electrode body 160 can provide support for the corresponding uncoated area 110e of the active material layer to prevent wrinkling of the uncoated area of the active material layer. In the negative electrode 101 of this structure, since only the area covered by the reinforcing layer 190 is cut, the laser energy used for cutting can be reduced, thus reducing energy consumption. In other words, compared to cutting the area covered by the active material layer (as described below...), Figure 6A and Figure 6B As described, the laser energy is lower.
[0053] In some embodiments requiring more layers of uncoated active material, the height of the negative electrode tab 150 along direction D1 is 35mm-38mm, which is higher than the conventional height of existing tabs (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 higher, making it more prone to wrinkling. By providing a reinforcing layer 190 at the negative electrode tab 150, and setting the preset spacing G to a range of 0.1mm-1.1mm and the W1 / G range to 22-400, wrinkling of the uncoated active material area in the multilayer tab can be effectively prevented, while also avoiding mutual dissolution and bulging between the reinforcing layer 190 and the negative electrode active material layer 130.
[0054] In some embodiments, the maximum width of the reinforcing layer 190 in direction D1 is W2. The value range of W1 / W2 can be 25-7.5. In some embodiments, the maximum width W2 of the reinforcing layer 190 is 4mm-6mm, for example, 6mm. By using the above-mentioned value range of W1 / W2, the ratio of the maximum width W1 of the uncoated area 110e of the active material layer to the maximum width W2 of the reinforcing layer 190 can be within a suitable range. This ensures that when the corresponding maximum width W1 is large, the reinforcing layer 190 has a suitable width to effectively provide support and prevent wrinkling in the uncoated area of the active material layer; and when the maximum width W1 is small, the reinforcing layer 190 also has a suitable width to avoid the reinforcing layer area being too large, occupying too much of the tab welding area, and affecting the tab welding.
[0055] In an embodiment where a negative electrode, a positive electrode, and a separator are sequentially stacked and wound to form a wound electrode assembly 120, the ratio N / n of the number of negative electrode tabs (N) to the number of winding turns of the negative electrode (n) ranges from 1.1 to 2. The number of winding turns of the negative electrode is counted one turn at a time from the starting end of the negative electrode outwards along the winding direction. To increase the current-carrying area and reduce the DC resistance (DCR), when the number of tabs increases, for multi-tab electrode assemblies, a longer length is required when the outer tabs are bent and directly welded to the adapter or electrode post. Therefore, for multi-tab electrode assemblies, the above-mentioned range of values for the maximum width W1 of the uncoated area 110e of the active material layer and the maximum width W2 of the reinforcing layer 190 can improve problems such as wrinkling in the uncoated area of the active material layer, tab insertion, and edge turning.
[0056] On either of the two surfaces 1101 and 1102 of the negative electrode current collector 110, taking surface 1101 as an example, the reinforcing layer 190 has a maximum thickness T1, and the negative electrode active material layer 130 has a maximum thickness T2. The maximum thickness T2 of the negative electrode active material layer 130 can be the thickness of the flat region 130b. On either surface of the negative electrode current collector 110, the thickness of the flat region 130b and the thickness of the reinforcing layer 190 can be uniform (within the process error range). In some embodiments, the value range of T1 / T2 is 0.1-0.5. This range of T1 / T2 can take into account both the thickness of the reinforcing layer 190 and the thickness of the negative electrode active material layer 130, and can also play a good role in supporting the electrode tab when the reserved spacing G is provided.
[0057] In some embodiments, the maximum thickness T1 of the reinforcing layer 190 on any surface of the negative electrode current collector 110 is 5 μm-25 μm. If the thickness is less than 5 μm, the reinforcing layer 190 is too thin and may not be effective in preventing wrinkling of the uncoated areas of the active material layer.
[0058] 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 to achieve a grayscale value of 0-110. In some embodiments, the color developer may be carbon black. If the reinforcing layer 190 does not contain a color developer, it will be a light color (e.g., white) with a high grayscale value. This would result in a small recognizable color difference between the negative 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 identify, leading to 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 0-110, thereby solving the problem of difficulty in identification by image recognition devices and facilitating the identification 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.
[0059] In some embodiments, the material of the reinforcing layer 190 may include ceramic, 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 current collector 110 is >300 N / m. Furthermore, the ceramic design can also provide support for the reinforcing layer 190. The synergistic effect of the ceramic, aqueous binder, and colorant improves the design of the uncoated area width of the active material layer within the specific range of W1 / G mentioned above, resulting in a larger uncoated area width of the active material layer.
[0060] Figure 6A This is a schematic diagram of the negative electrode sheet after the negative electrode tab has been cut, according to some other embodiments. Figure 6B According to other embodiments, corresponding to Figure 6A A magnified view of region A2 in the diagram. Figure 6A and Figure 6B Several aspects of the illustrated embodiments are related to the above references. Figures 4A to 5 Similar to the descriptions below, the main focus is on... Figure 6A and Figure 6B The differences between the illustrated embodiments are as follows. See also: Figure 6A and Figure 6BAs shown, the uncoated area 110e of the active material layer includes the negative electrode tab 150, and no transition region is provided between the negative electrode tab 150 and the coated area 110f of the active material layer. In this embodiment, the reinforcing layer 190 is located only on 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. A portion of the negative electrode active material layer 130 may extend to the surface of the negative electrode tab 150. The gap between the reinforcing layer 190 and the negative electrode active material layer 130 is located on the negative electrode tab 150.
[0061] In this structure, the area covered by both the reinforcing layer 190 and the negative electrode active material layer 130 in the negative electrode sheet 101 is cut, which increases the area of the negative electrode active material layer 130 in the electrode body 160, thereby improving 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 tab support, thus improving the tab support capability.
[0062] The maximum width of the uncoated area 110e of the active material layer in direction D1 is W1. In direction D2, the width of the uncoated area 110e is uniform (within the process tolerance range). A reinforcing layer 190 covers a portion of the uncoated area 110e of the active material layer, and the reinforcing layer 190 is spaced apart from the negative electrode active material layer 130 in direction D1 by a predetermined spacing G. In some embodiments, the value of W1 / G ranges from 22 to 400. In some embodiments, the value of G ranges from 0.1 mm to 1.1 mm. In some embodiments, considering process capability, the predetermined spacing G can, for example, range from 0.1 mm to 1 mm, or from 0.1 mm to 0.5 mm. The aforementioned ranges of the predetermined spacing G and the maximum width W1 take into account both the uncoated area 110e of the active material layer (which can be referred to as the current collector blank) and the predetermined spacing G, enabling the setting of a suitable predetermined spacing G within a suitable maximum width W1 range of the uncoated area 110e of the active material layer. This can prevent the reinforcement layer 190 from merging with the negative electrode active material layer 130 due to an excessively small preset spacing G, and also avoid bulging edges and fusion dislocations caused by merging.
[0063] The maximum width of the reinforcing layer 190 in direction D1 is W2. The value range of W1 / W2 can be 25-7.5. In this embodiment, the maximum width W2 of the reinforcing layer 190 is 4mm-6mm, for example, 6mm. By using the above-mentioned value range of W1 / W2, the ratio of the maximum width W1 of the uncoated area 110e of the active material layer to the maximum width W2 of the reinforcing layer 190 can be within a suitable range. This ensures that when the corresponding maximum width W1 is large, the reinforcing layer 190 has a suitable width to effectively provide support and prevent wrinkling in the uncoated area of the active material layer; and when the maximum width W1 is small, the reinforcing layer 190 also has a suitable width to avoid the reinforcing layer area being too large, occupying too much of the tab welding area, and affecting the tab welding.
[0064] Figure 7 A schematic diagram is shown when the electronic device according to an embodiment of this application is a vehicle. See also Figure 7 This application 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, front, or rear 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 extended-range 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 application embodiment does not impose any special limitations on the above-described 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 application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A secondary battery, characterized in that, Includes an electrode assembly, the electrode assembly comprising: A negative electrode, a positive electrode, and a separator disposed between the negative electrode and the positive electrode. The negative electrode includes a negative active material layer and a negative current collector. The negative current collector includes an active material layer coated area covered on at least one side by the negative active material layer and an uncoated active material layer area not covered by the negative active material layer. The coated active material layer area and the uncoated active material layer area are arranged adjacent to each other along a predetermined direction, wherein the maximum width of the uncoated active material layer area in the predetermined direction is W1; and A reinforcing layer covers a portion of the uncoated area of the active material layer, and a predetermined spacing G exists between the reinforcing layer and the negative electrode active material layer in the predetermined direction. The value of G ranges from 0.1mm to 1.1mm, and the value of W1 / G ranges from 22 to 400.
2. The secondary battery according to claim 1, characterized in that, The uncoated area of the active material layer includes tabs, and a transition area is provided between the tabs and the coated area of the active material layer. The reinforcing layer is located on the surface of a portion of the transition area and a portion of the tabs.
3. The secondary battery according to claim 1, characterized in that, The uncoated area of the active material layer includes tabs, and a portion of the negative electrode active material layer is disposed on the surface of a portion of the tabs along the preset direction.
4. The secondary battery according to claim 1, characterized in that, The negative electrode current collector has two surfaces opposite each other along its thickness direction. The reinforcing layer on either of the two surfaces has a maximum thickness T1, and the negative electrode active material layer on either surface has a maximum thickness T2. The value of T1 / T2 ranges from 0.1 to 0.
5.
5. The secondary battery according to claim 1, characterized in that, The maximum width of the reinforcing layer in the preset direction is W2, and the value range of W1 / W2 is 25-7.
5.
6. The secondary battery according to claim 1, characterized in that, The negative electrode, the positive electrode, and the separator are sequentially stacked and wound to form the electrode assembly. The uncoated area of the active material layer includes tabs. The number of turns of the negative electrode is n, and the number of tabs is N. The value of N / n ranges from 1.1 to 2.
7. The secondary battery according to claim 1, characterized in that, The grayscale value of the reinforcing layer is 0-110, or, The thickness of the negative electrode current collector is less than or equal to 5.5 μm.
8. The secondary battery according to claim 1, characterized in that, The secondary battery is a prismatic battery, and the secondary battery further includes: A housing having an opening, the electrode assembly being disposed within the housing; A cover assembly that seals the opening of the housing; The pole passes through the cover plate assembly and is electrically isolated from the cover plate assembly; An adapter piece is disposed on the side of the cover plate assembly facing the electrode assembly and electrically connects the electrode post to the electrode assembly. The uncoated area of the active material layer includes a bent portion and a connecting portion, wherein the bent portion connects the coated area of the active material layer and the connecting portion; the reinforcing layer is located at the bent portion, and the adapter piece is welded to the connecting portion.
9. A battery pack, characterized in that, Includes the secondary battery as described in any one of claims 1-8.
10. An electronic device, characterized in that, Includes the battery pack as described in claim 9.