Battery

Abstract

The invention provides a battery, the battery comprises a first pole piece, a diaphragm and a second pole piece which are sequentially stacked, the first pole piece comprises a first current collector, a first active layer and a gap, the second pole piece comprises a second current collector, the first active layer is provided with a first tab groove, and the first tab groove and the gap are oppositely arranged along a first direction; at least part of the first tab is arranged in the first tab groove and is connected with the first current collector, the plurality of second tabs are electrically connected with the second current collector, the plurality of second tabs are stacked and are mutually connected to form a tab bundle, and at least part of the orthographic projection of the first insulating part along the second direction covers the first tab; the width of the first tab in the third direction is W1, the first distance between the first insulating part and the notch in the first direction is T, and T is larger than or equal to two times of W1; wherein the second direction is along the thickness direction of the battery, and the first direction, the second direction and the third direction are mutually vertical in pairs. The battery disclosed by the invention is relatively good in cycle performance and quick charge performance and relatively high in energy density.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a battery. BACKGROUND

[0002] In the prior art, a tab slot is arranged on the active layer near the middle region of the length direction of the tab, and a tab is led out in the tab slot, which is a tab centering structure. The tab centering structure shortens the current output path, reduces the internal resistance of the battery, and thus improves the cycle life of the battery. However, the tab centering structure will cause the current to concentrate at the tab position during the charging and discharging process, resulting in excessive current at the tab position, which will cause the local temperature near the tab to be too high, leading to a decrease in the ability of the local active material to release lithium, and a decrease in the cycle and fast charging capacity of the battery. In particular, for a negative tab centering structure containing silicon-based material, the silicon-based material has poor electrical conductivity and will undergo a large volume change during the cycle process, which will exacerbate the heating phenomenon at the tab position and affect the connection stability of the tab and the current collector, reducing the advantages brought by the negative tab centering. Another multi-tab tab structure can improve the problem of local heat accumulation caused by the tab centering structure and improve the fast charging performance of the battery. However, the multi-tab tab structure has multiple tabs stacked, and additional welding of a switching tab is required, resulting in a large space occupied in the battery. In particular, when the positive electrode adopts a positive multi-tab structure, the thickness of the positive current collector is thick, and the multiple positive tabs integrated with the positive current collector are stacked, which further exacerbates the problem of large space occupation, reduces the energy density of the battery, and requires the use of insulating adhesive tape on the side of the positive multi-tab tab near the tab to reduce the risk of burr generation during the die cutting process. This will reduce the content of the positive active material and further reduce the energy density of the battery.

[0003] Therefore, how to improve the energy density while ensuring the fast charging performance is a problem to be solved. SUMMARY

[0004] Based on this, the present application provides a battery to solve the problems in the related art.

[0005] The battery provided by the present application comprises:

[0006] The first tab, the diaphragm and the second tab are sequentially stacked, the polarities of the first tab and the second tab are opposite, the first tab comprises a first current collector, a first active layer and a notch, the second tab comprises a second current collector, the first active layer is provided with a first tab slot, and the first tab slot and the notch are oppositely arranged along a first direction;

[0007] The first tab, the diaphragm and the second tab are sequentially stacked, the polarities of the first tab and the second tab are opposite, the first tab comprises a first current collector, a first active layer and a notch, the second tab comprises a second current collector, the first active layer is provided with a first tab slot, and the first tab slot and the notch are oppositely arranged along a first direction;

[0008] A plurality of second tabs are electrically connected with the second current collectors, and the plurality of second tabs are arranged in layers and connected with each other to form a tab bundle;

[0009] A first insulating piece, in the second direction, a projection of the first insulating piece at least partially covers the first tab;

[0010] A width of the first tab in the third direction is W1, and a first interval of the first insulating piece and the gap in the first direction is T, T is greater than or equal to 2 times W1;

[0011] The second direction is along the thickness direction of the battery, and the first direction, the second direction, and the third direction are perpendicular to each other in pairs.

[0012] In a possible implementation, the second tabs are integrally formed with the corresponding second current collectors, and the number of the second tabs is greater than the number of the first tabs;

[0013] In the first direction, a length L1 of the first insulating piece is less than or equal to the first interval T.

[0014] In a possible implementation, T satisfies: 20mm≤T≤100mm; and / or, L1 and T satisfy: 1≤T / L1≤7.5.

[0015] In a possible implementation, the first insulating piece includes a first insulating layer and a second insulating layer, the first insulating layer is arranged on a surface of the first tab, and the second insulating layer is arranged on a surface of the first insulating layer away from the first tab;

[0016] In the second direction, a projection of the first insulating layer at least partially covers the first tab slot, a projection of the second insulating layer at least partially covers the first tab slot, and the projection of the first insulating layer and the projection of the second insulating layer partially overlap and partially stagger; and / or, in the first direction, the first insulating layer is arranged close to the gap relative to the second insulating layer.

[0017] In a possible implementation, the battery has a first thickness H1 and a second thickness H2, the first thickness H1 corresponds to a position where the first tab is located, and the second thickness H2 corresponds to a position where the gap is located;

[0018] The first thickness H1 and the second thickness H2 satisfy: 20μm≤H1-H2≤100μm.

[0019] In a possible implementation, in the first direction, a projection of the first tab slot is located in a projection of the gap;

[0020] And / or, in the third direction, a size W1 of the first tab and a size W2 of the gap satisfy: 1.5≤W2 / W1≤3.0.

[0021] In a possible implementation, along the third direction, the size W3 of the first insulating layer and the size W2 of the gap satisfy: 1.2≤W2 / W3≤2.

[0022] And / or, along the third direction, the width W4 of the second insulating layer and the size W2 of the gap satisfy: 1≤W4 / W2≤1.8.

[0023] In a possible implementation, the second tab includes a second active layer arranged on a side surface of the first tab facing the first tab where the first tab ear is located, the second active layer is provided with a first groove, and the first groove is arranged in a staggered manner with the first tab ear; and the first groove and the first tab ear groove are arranged in a corresponding manner along the second direction.

[0024] The first insulating layer is at least partially located in the first groove along the second direction, and the second insulating layer is at least partially located in the first groove along the second direction.

[0025] In a possible implementation, the first tab and the second tab are located on the same side of the battery along the first direction, and the battery further includes a second insulating member; the battery includes a first outer surface and a second outer surface arranged opposite to each other along the second direction.

[0026] The second insulating member is arranged on the first outer surface and / or the second outer surface, and along the second direction, a projection of the second insulating member at least partially overlaps with a projection of the gap.

[0027] In a possible implementation, the first tab is a positive tab, and the second tab is a negative tab; the first tab has a first winding start end, and the second tab has a second winding start end; the first tab has a first flat section, a first bent section, and a second flat section located at an innermost circle of the battery; an end of the first flat section away from the first bent section is the first winding start end; the first bent section is arranged opposite to the second winding start end; the second winding start end extends in a direction opposite to the first winding start end; the second tab includes a second active layer, and the second active layer includes a silicon-based material.

[0028] A side surface of the first bent section facing the second winding start end is provided with a third insulating member; and / or, the separator includes a separator overhang portion beyond the second winding start end, and the separator overhang portion is folded to form a folded section; the folded section at least partially overlaps with the second tab, and a size of the overlapping portion along the third direction is 0.5mm-8mm.

[0029] The battery of the embodiment of the application comprises a first pole piece, a diaphragm, a second pole piece, a first lug, a second lug and a first insulating piece, the first pole piece comprises a first current collector, a first active layer and a notch, the second pole piece comprises a second current collector, the first pole piece and the second pole piece are arranged to be used for electrochemical reaction with electrolyte to store or release electric energy, the diaphragm is arranged to isolate the first pole piece and the second pole piece, the first lug is arranged to transmit the current of the first pole piece, the second lug is arranged to transmit the current of the second pole piece, the first lug slot is arranged on the first active layer to expose part of the first current collector, thereby facilitating the connection of the first lug and the first current collector, the first lug (or the first lug slot) is arranged close to the middle region of the first pole piece along a third direction (here, the middle position of the first pole piece refers to the position of the first lug in the length direction of the first pole piece, and the first lug is located in the region of 1 / 4-3 / 4 of the length of the first pole piece), and the first insulating piece is arranged to cover the first lug to protect the connection part of the first lug and the first current collector.

[0030] Since the first pole piece of the battery is provided with the first lug arranged in the middle region of the first pole piece, the transmission path of the current can be shortened when the first pole piece transmits the current, thereby reducing the internal resistance of the battery and improving the cycle performance of the battery. Since the second pole piece of the battery is provided with the lug bundle composed of a plurality of second lugs, the current path is further shortened when the battery charges and discharges, the current transmission resistance is greatly reduced, the fast charging performance of the battery is improved, and the heat generated when the battery charges and discharges is distributed on the entire second pole piece instead of being concentrated near the region where the second lugs and the second current collector are connected, which can avoid local overheating of the second pole piece, make the temperature field in the battery more uniform, and improve the cycle and fast charging performance of the battery. Through the cooperative design of the first lug arranged in the middle of the first pole piece and the plurality of second lugs arranged on the second pole piece, the space of the battery is reasonably utilized, and the energy density, cycle performance and fast charging performance of the battery can be well balanced.

[0031] Due to the fact that the first tab is provided with a notch and the notch is opposite to the first tab slot along the first direction, and due to the fact that the first tab is covered with the first insulating piece, there are at least two regions with different thicknesses of the first tab along the first direction, that is, after the first tab is connected with the first insulating piece, the thickness of one side of the first tab along the first direction is increased, and after the other side of the first tab along the first direction is provided with the notch, the thickness of the other side of the first tab is reduced, and after the battery is hot-pressed, a slope region is formed in the battery, which can store a part of electrolyte on the side of the battery close to the first tab, improve the problem that the current density is large at the position of the first tab and the electrolyte is consumed fast, and the stored electrolyte can quickly supplement the electrolyte, reduce the temperature rise near the first tab, and meanwhile, the existence of the slope region can also ensure that the electrolyte flows fast to the middle region of the battery, realize uniform wetting of the middle region of the battery, and further improve the cycle performance of the battery.

[0032] In the embodiments of the present application, the width of the first tab along the third direction is W1, the first insulating piece and the notch have a first interval T along the first direction, and the first interval T needs to be greater than 2 times the width W1 of the first tab, which can on the one hand provide a space for storing electrolyte on the side of the battery close to the first tab, improve the problem that the current density is large on the side of the battery with the first tab and the electrolyte is consumed fast, and the first interval T needs to be greater than 2 times the width W1 of the first tab to make the space for storing electrolyte not too large, so as to avoid affecting the uniformity of the electrolyte wetting the whole battery, and on the other hand, make the slope region longer in the first direction and narrower in the third direction, so as to make the slope region transition gently in the first direction, and further improve the interface bonding performance between the first tab and the separator and between the second tab and the separator, thereby improving the cycle performance of the battery.

[0033] In addition to the technical problems solved by the embodiments of the present application, the technical features constituting the technical solutions and the beneficial effects brought by these technical features described above, other technical problems solved by the battery provided by the present application, other technical features included in the technical solutions and the beneficial effects brought by these technical features will be further described in detail in the specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creating any creative labor.

[0035] Figure 1A structural schematic diagram of a battery provided by an embodiment of the present application is shown in FIG. 1.

[0036] Figure 2 Another structural schematic diagram of a battery provided by an embodiment of the present application is shown in FIG. 2.

[0037] Figure 3 A structural schematic diagram of a first pole piece, a first tab and a first insulating member in a battery provided by an embodiment of the present application is shown in FIG. 3.

[0038] Figure 4 A structural schematic diagram of a first pole piece and a first tab in a battery provided by an embodiment of the present application is shown in FIG. 4.

[0039] Figure 5 A structural schematic diagram of a second pole piece and a second tab in a battery provided by an embodiment of the present application is shown in FIG. 5.

[0040] Figure 6 A structural schematic diagram of a second pole piece, a second tab and a second insulating layer in a battery provided by an embodiment of the present application is shown in FIG. 6.

[0041] Figure 7 A structural schematic diagram of a second pole piece and a second insulating layer in a battery provided by an embodiment of the present application is shown in FIG. 7.

[0042] Figure 8 Still another structural schematic diagram of a battery provided by an embodiment of the present application is shown in FIG. 8.

[0043] Explanation of reference signs:

[0044] 100 - first pole piece; 110 - first tab slot; 120 - notch; 200 - diaphragm; 210 - folded section; 300 - second pole piece; 310 - first groove; 400 - first tab; 500 - second tab; 600 - first insulating member; 610 - first insulating layer; 620 - second insulating layer; 700 - second insulating member; 710 - first sub-insulating member; 720 - second sub-insulating member; 800 - third insulating member. DETAILED DESCRIPTION

[0045] 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 with reference to the drawings in the preferred embodiments of the present application. In the drawings, the same or similar reference signs represent the same or similar components or components with the same or similar functions throughout. The described embodiments are part of the embodiments of the present application, not all of the embodiments. The embodiments described below by reference to the drawings are exemplary and are intended to explain the present application, and cannot be understood as limiting the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts fall within the scope of protection of the present application. The embodiments of the present application will be described in detail below with reference to the drawings.

[0046] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0047] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0048] The terms "first," "second," and "third" (if any) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein.

[0049] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or display that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or display.

[0050] In existing technologies, a centrally located tab structure is used where the tab is led out in the middle region near the length of the electrode. This structure shortens the current output path and reduces the battery's internal resistance, thereby improving the battery's cycle life. However, during charging and discharging, the current in a centrally located tab structure can concentrate at the tab position, resulting in excessive current at the tab. This can lead to excessively high local temperatures near the battery tab, causing a decrease in the lithium insertion / extraction capability of the local active material, as well as a deterioration in the battery's cycle and fast-charging capabilities. This is especially true for centrally located tab structures for negative electrodes made of silicon-based materials. Silicon-based materials have poor conductivity and undergo significant volume changes during cycling, which exacerbates the heating phenomenon at the tab position and affects the connection stability between the tab and the current collector, thus reducing the advantages of a centrally located negative tab.

[0051] Another type of multi-tab electrode structure can improve the problem of localized heat accumulation caused by the centrally located tabs, thus enhancing the battery's fast-charging performance. However, the multi-tab structure involves multiple tabs stacked together, and additional welding of adapter tabs is required, resulting in a larger space occupied within the battery. This is especially true when the positive electrode uses a multi-tab structure; the thickness of the positive current collector, combined with the stacking of multiple integrally formed positive tabs, exacerbates the space occupation problem, reducing the battery's energy density. Furthermore, insulating tape needs to be placed on the side of the positive multi-tab electrode near the tabs to reduce the risk of burrs during die-cutting, which reduces the content of positive active material, further decreasing the battery's energy density. Therefore, how to improve energy density while ensuring fast-charging performance is a pressing issue that needs to be addressed.

[0052] In view of the above problems, this application provides a battery that uses a centrally located first electrode tab and a plurality of second electrodes in a coordinated design, and uses a first insulating element and a notch to achieve a thickness difference in the first electrode, thereby storing electrolyte on the side near the electrode tab. At the same time, since there are at least two regions of different thicknesses in the first electrode, the battery containing the first electrode forms a sloping structure, thereby maintaining good cycle performance of the battery while simultaneously improving the battery's fast charging performance and energy density.

[0053] The specific implementation of the battery provided in this application will be described in detail below with reference to the accompanying drawings.

[0054] Reference Figures 1 to 4 As shown, the battery provided in this embodiment includes a first electrode 100, a separator 200, a second electrode 300, a first tab 400, a plurality of second tabs 500, and a first insulating member 600. The first electrode 100, separator 200, and second electrode 300 are sequentially stacked and wound. The first electrode 100 includes a first current collector, a first active layer, and a notch 120. The second electrode 300 includes a second current collector. The first active layer has a first tab groove 110. The first tab groove 110 and the notch 120 are arranged opposite to each other along a first direction. At least a portion of the first tab 400 is disposed in the first tab groove 110 and connected to the first current collector. Along a second direction, the orthographic projection of the first insulating member 600 at least partially covers the first tab 400. The second tabs 500 are integrally disposed with the second current collector, and a plurality of second tabs 500 are stacked and interconnected to form a tab bundle.

[0055] Reference Figure 3 As shown, the width W1 of the first tab 400 along the third direction, and the first spacing T of the first insulating member 600 and the notch 120 along the first direction, satisfy: T / W1≥2.

[0056] The second direction is along the thickness direction of the battery, and the first, second, and third directions are mutually perpendicular. The first direction can be referred to as the X direction in the attached figure, the second direction as the Y direction in the attached figure, and the third direction as the Z direction in the attached figure.

[0057] In this embodiment, one of the first electrode 100 and the second electrode 300 is a positive electrode and the other is a negative electrode. When the second electrode 300 is a negative electrode, silicon-based materials such as silicon-carbon materials or silicon-oxygen materials can be used as raw materials to make the negative electrode active layer, thereby effectively improving the energy density of the battery. The mass content of silicon element in the negative electrode active layer is between 1.5% and 50%. This can control the risk of battery expansion and electrode breakage caused by excessive expansion due to volume changes of silicon-based materials in the negative electrode during battery cycling, while improving the energy density of the battery.

[0058] The battery in this embodiment may also include an adapter tab, with the tab bundle connected to the adapter tab. The tab bundle is disposed inside the battery, and the adapter tab extends outside the battery, so that the adapter tab can be connected to an external circuit.

[0059] It should be noted that in some embodiments, the first electrode 100 in this application is a positive electrode and the second electrode 300 is a negative electrode containing silicon-based material. In this case, the first tab 400 is a positive tab and the second tab 500 is a negative tab. The battery formed by the positive tab in the middle structure combined with the structure of multiple negative tabs can reduce the problem of local heat accumulation during battery cycling, and simultaneously improve the energy density and cycle performance of the battery by achieving fast charging performance.

[0060] The number of second electrodes 500 is greater than the number of first electrodes 400, and the number of second electrodes 500 can be two or more, for example... Figure 1 This illustrates a scheme where the second electrode 300 is equipped with four second electrode tabs 500. Figure 5 This diagram illustrates a scheme where the second electrode 300 has five second electrode tabs 500. The number of first electrode tabs 400 can be between one and three, for example... Figure 1 The diagram illustrates a scheme where the first electrode 100 is equipped with one first electrode tab 400.

[0061] The battery in this embodiment includes a first electrode 100, a separator 200, a second electrode 300, a first tab 400, a second tab 500, and a first insulating member 600. The first electrode 100 includes a first current collector, a first active layer, and a notch 120. The second electrode 300 includes a second current collector. The first electrode 100 and the second electrode 300 are configured to undergo an electrochemical reaction with the electrolyte to store or release electrical energy. The separator 200 is configured to isolate the first electrode 100 and the second electrode 300 and allow lithium ions to permeate. The first tab 400 is used to transmit the current of the first electrode 100. The second tab 500 is provided to transmit the current of the second electrode 300. The first tab groove 110 is opened on the first active layer to expose part of the first current collector, thereby facilitating the connection between the first tab 400 and the first current collector. The first tab 400 is arranged in a third direction near the middle area of ​​the first electrode 100. The first insulating member 600 is provided to cover the first tab 400 to protect the connection between the first tab 400 and the first current collector.

[0062] Since the first electrode 100 of the battery is provided with a first tab 400, and the first tab 400 is located in the middle region of the first electrode 100, the current transmission path can be shortened when the first electrode 100 transmits current, thereby reducing the internal resistance of the battery and improving the cycle performance of the battery.

[0063] Because the battery's second electrode 300 has a tab bundle composed of multiple second tabs 500, the current path is further shortened during charging and discharging, the current transmission resistance is significantly reduced, and the battery's fast-charging performance is improved. Furthermore, the heat generated during charging and discharging is distributed across the entire second electrode 300, rather than concentrated near the area where a few second tabs 500 connect to the second current collector, preventing localized overheating of the second electrode 300 and resulting in a more uniform internal temperature field, thus improving the battery's cycle and fast-charging performance. Through the coordinated design of a first tab 400 in the first electrode 100 and multiple second tabs 500 in the second electrode 300, the battery space is utilized efficiently, effectively balancing the battery's energy density, cycle performance, and fast-charging performance.

[0064] Because a notch 120 is made on the first electrode 100, and the notch 120 is disposed opposite to the first tab groove 110 along the first direction, and because the first tab 400 is covered with the first insulating member 600, the first electrode 100 will have a thickness difference in the first direction. That is, after the first insulating member 600 is connected to the first electrode 100, the thickness of the first electrode 100 on the side closer to the first tab 400 along the first direction will increase, and after the notch 120 is made on the other side of the first electrode 100 along the first direction, the thickness of the other side of the first electrode 100 will decrease. The thickness of the first electrode 100 between the first insulating member 600 and the notch 120 is in the middle. After the battery is hot-pressed, a gently transitioning slope area is formed inside the battery.

[0065] The sloped region has a greater thickness on the side near the first tab 400, which allows a portion of the electrolyte to be stored on this side of the battery. This mitigates the problem of rapid electrolyte consumption due to the high current density at the first tab 400. The stored electrolyte can quickly replenish the first tab 400, reducing its temperature rise. Simultaneously, the sloped region ensures rapid electrolyte flow from the first tab 400 side to the internal central region of the battery, achieving uniform wetting of the central region and thus improving the battery's cycle performance. This also prevents lithium plating during cycling caused by poor wetting.

[0066] In this embodiment, the width of the first tab 400 along the third direction is W1, and the first insulating member 600 and the notch 120 have a first spacing T along the first direction. The first spacing T needs to be greater than twice the width W1 of the first tab 400. On the one hand, this ensures that the space for electrolyte stored on the side of the battery close to the first tab 400 is not too large, thus avoiding affecting the uniformity of electrolyte wetting of the battery as a whole. On the other hand, this makes the slope region longer in the first direction and narrower in the third direction, so that the slope region transitions smoothly in the first direction, thereby improving the interfacial bonding performance between the first electrode 100 and the separator 200, and between the second electrode 300 and the separator 200, thereby improving the cycle performance of the battery.

[0067] In some embodiments, the first distance T between the first insulating member 600 and the notch 120 is between 20 mm and 100 mm. On the one hand, if the first distance T is less than 20 mm, the three-section slope region of the battery will not be gentle enough, resulting in poor interfacial bonding of the battery and thus reducing the cycle performance of the battery. On the other hand, if the first distance T is greater than 100 mm, the size of the notch 120 will be too large. When the battery is hot-pressed, the part of the second electrode 300 corresponding to the notch 120 of the first electrode 100 cannot be effectively supported, resulting in a large deformation in the local area of ​​the second electrode 300. The second electrode 300 drives the separator 200 to undergo large deformation, which in turn causes local warping of the battery, thus affecting the cycle performance of the battery.

[0068] Therefore, a first spacing T between 20 mm and 100 mm allows for a smooth transition in the slope region, thereby improving the interfacial bonding performance of the battery and reducing deformation issues during hot pressing on the side of the battery near the notch 120, thus improving the battery's cycle performance. Furthermore, the first spacing T needs to be greater than twice the width W1 of the first tab 400, so that the slope region is longer in the first direction and narrower in the third direction, resulting in a smooth transition in the slope region in the first direction, further improving the interfacial bonding performance of the battery and thus enhancing its cycle performance.

[0069] The width W1 of the first electrode 400 can be between 5 mm and 12 mm.

[0070] For example, the first spacing T can be any one of 20mm, 30mm, 40mm, 45mm, 50mm, 66mm, 82mm, or 100mm, or fall within any two of these values. The width W1 of the first tab 400 can be any one of 5mm, 6mm, 7mm, 8mm, 9mm, or 10mm, or fall within any two of these values.

[0071] In one possible implementation, along the first direction, the dimension L1 of the first insulating element 600 and the first spacing T satisfy: 1≤T / L1≤7.5.

[0072] In the first direction, a notch 120 is provided on one side of the first electrode 100, and a first insulating member 600 is provided on the other side. If the notch 120 is too large, the battery will lose more capacity and it will not be conducive to forming a gentle transition slope area. If the notch 120 is too small, it will not be conducive to forming a thickness gradient change, and thus it will not be conducive to forming a slope area. If the first insulating member 600 is too small, it will not be conducive to ensuring the protective effect of the first insulating member 600. If the first insulating member 600 is too large, it will seriously waste the energy density of the battery and make the area with different thicknesses of the battery too large, increasing the ineffective size of the battery and thus reducing the energy density of the battery.

[0073] If T / L1 is less than 1, the first spacing T will be too small and the size L1 of the first insulating component 600 will be too large. This will result in the first insulating component 600 covering too large an area of ​​the active material on the first electrode 100, which is not conducive to improving the energy density of the battery. At the same time, if the size L1 of the first insulating component 600 is too large, the overlap between the first insulating component 600 and the first electrode 100 will be too large, which will increase the area of ​​uneven battery thickness, reduce the overall thickness consistency of the battery, and make it difficult to form a smooth transition slope area. This will reduce the hot-pressing formation effect of the battery and lead to poor adhesion of the first electrode 100, separator 200 and second electrode 300 on the side near the notch 120, thereby deteriorating the cycle performance of the battery.

[0074] On the other hand, when T is too small and L1 is too large, the first insulating element 600 is closer to the notch 120. The overlapping area between the first insulating element 600 and the first active layer will form a local "thickened hard point". During cycling, shear stress will be generated between the active material at the edge of the first insulating element 600 and the notch 120, causing the first electrode 100 to tear along the edge of the notch 120, reducing the cycle performance and safety of the battery.

[0075] If T / L1 is less than 7.5, the first spacing T will be too large and the size L1 of the first insulating member 600 will be too small. On the one hand, if the first insulating member 600 is too small, it cannot effectively cover and fix the area of ​​the first tab 400 where the first tab groove 110 is located, and the first insulating member 600 will be prone to falling off or the insulation protection effect will be deteriorated. On the other hand, it is impossible to form a slightly thicker area on the side of the battery near the first tab 400, and it is impossible to effectively store electrolyte on the side near the first tab 400 to reduce the temperature rise near the first tab 400, thereby failing to improve the cycle performance of the battery.

[0076] To achieve a balance, T / L1 can be set between 1 and 7.5. On the one hand, this reduces the risk of the first electrode 100 being torn near the notch 120. On the other hand, it ensures that a gentle transition slope area can be formed on the battery for electrolyte storage, improving cycle performance. It also facilitates the first insulating element 600 completely covering the area where the first tab 400 connects to the first current collector, and completely covering the first tab groove 110, thus improving the protective effect of the first insulating element 600.

[0077] For example, T / L1 can be any one of the values ​​1, 2, 2.2, 3, 4, 4.5, 5, 7.5 or fall within the range of any two values.

[0078] Reference Figure 3 , Figure 4As shown, in a specific implementation, the first insulating member 600 includes a first insulating layer 610 and a second insulating layer 620. The first insulating layer 610 is disposed on the surface of the first electrode tab 400, and the second insulating layer 620 is disposed on the surface of the first insulating layer 610 facing away from the first electrode tab 400.

[0079] In other words, the first tab 400 is sequentially fitted with a first insulating layer 610 and a second insulating layer 620. Compared to only having a first insulating layer 610 or only having a second insulating layer 620, the first insulating layer 610 and the second insulating layer 620 can jointly protect the connection between the first tab 400 and the first current collector. This effectively prevents the first tab 400 from shifting or falling off during battery expansion or vibration, and prevents either the first insulating layer 610 or the second insulating layer 620 from being worn or failing to provide insulation protection due to weak adhesion after cycling. Furthermore, the sequential application of the first insulating layer 610 and the second insulating layer 620 creates a thickness gradient in the first direction on the first electrode 100, which facilitates the formation of a sloped area for electrolyte storage after battery formation.

[0080] It should be noted that the connection between the first tab 400 and the first current collector can be either welded or made with conductive adhesive; the specific method is not limited.

[0081] Along the second direction, the orthographic projection of the first insulating layer 610 along the second direction at least partially covers a portion of the first tab groove 110, and the orthographic projection of the second insulating layer 620 at least partially covers a portion of the first tab groove 110. The orthographic projections of the first insulating layer 610 and the second insulating layer 620 partially overlap and partially offset each other. Along the first direction, the first insulating layer 610 is positioned closer to the notch 120 relative to the second insulating layer 620.

[0082] Thus, the first insulating layer 610 covers the first tab groove 110 in the first direction, and a portion of the first insulating layer 610 extends beyond the first tab groove 110 in the first direction and extends toward the notch 120. The second insulating layer 620 completely covers the first tab groove 110 in the third direction, and a portion of the second insulating layer 620 extends beyond the first tab groove 110 in the second direction and extends toward both sides of the first tab groove 110. In this way, the two layers combine to ensure that the first insulating element 600 can completely cover the connection between the first tab 400 and the first current collector, preventing the first insulating layer 610 and the second insulating layer 620 from completely overlapping. This would prevent the formation of a local thickened area where the first insulating element 600 and the first electrode 100 completely overlap, increasing the risk of the first insulating element 600 generating a large shear force on the first electrode 100 during the cycle and causing the first electrode to break.

[0083] It is understandable that when the first insulating layer 610 is positioned close to the notch 120 relative to the second insulating layer 620, the first distance T between the first insulating member 600 and the notch 120 can be considered as the distance between the first insulating layer 610 and the notch 120.

[0084] In some embodiments, since the first insulating layer 610 is closer to the surface of the first tab 400, and the first tab 400 is at a higher temperature when transmitting current, the first insulating layer 610 can be made thicker than the second insulating layer 620 so that the first insulating layer 610 needs better high-temperature resistance, thereby preventing the first insulating layer 610 from shrinking or breaking under high temperature conditions.

[0085] In some embodiments, since the first insulating layer 610 is closer to the surface of the first tab 400, and the temperature of the first tab 400 is higher when transmitting current, the first insulating layer 610 can be made of adhesive paper with better high temperature resistance, such as adhesive or adhesive paper mixed with ceramics, high temperature polyimide adhesive, etc., thereby preventing the first insulating layer 610 from shrinking or breaking under high temperature conditions, resulting in poor insulation effect.

[0086] In some other embodiments, the peel strength of the second insulating layer 620 is greater than that of the first insulating layer 610, thereby effectively preventing the second insulating layer 620 from falling off, and thus preventing the first insulating layer 610 from falling off after the second insulating layer 620 falls off, thereby ensuring the protective effect of the first insulating layer 610 on the connection area between the first electrode 400 and the first current collector.

[0087] Reference Figure 1 , Figure 2 As shown, in one possible implementation, the battery has a first thickness H1 and a second thickness H2, where the first thickness H1 corresponds to the location of the first tab 400, and the second thickness H2 corresponds to the location of the notch 120. The first thickness H1 and the second thickness H2 satisfy: 20μm≤H1-H2≤100μm.

[0088] In other words, because the first insulating element 600 is attached to the first tab 400, the battery thickness at the location of the first tab 400 will increase, while the notch 120 will decrease the battery thickness at its location. After battery formation, the battery thickness at the two locations will be different, which indicates that a slope region has been formed inside the battery. The difference in battery thickness between the two locations is between 20μm and 100μm. This allows the electrolyte to be retained in the liquid storage space formed on the side near the first tab 400 during the smooth transition of the slope region, so as to quickly replenish the electrolyte for the first tab 400. On the other hand, it ensures that the thickness of different areas of the battery does not differ too much, thereby avoiding increasing the overall unevenness of the battery and thus avoiding increasing the interfacial resistance between the first electrode 100 and the separator 200, thereby avoiding deterioration of the battery's cycle performance.

[0089] For example, H1-H2 can be any one of the values ​​of 20μm, 40μm, 50μm, 65μm, 88μm, 90μm, and 100μm, or fall within any two of these values.

[0090] In one possible implementation, along the first direction, the orthographic projection of the first tab groove 110 lies within the orthographic projection of the notch 120. That is, the first tab groove 110 and the notch 120 are arranged opposite each other along the first direction, and in the third direction, the width of the notch 120 is greater than the width of the first tab groove 110.

[0091] This is because during the processing, the active material is cleaned on a large first electrode sheet 100, and the large first electrode sheet 100 is cut into multiple smaller first electrode sheets 100. Part of the grooves that are cleaned form the first electrode tab groove 110, and the other part is cut off to remove the first current collector, thus forming the notch 120. This helps to completely remove the exposed area of ​​the first current collector, thereby reducing the safety risk of the battery, and at the same time, it can reduce the burrs on the edge of the notch 120.

[0092] Reference Figure 3 As shown, in one possible implementation, along a third direction, the size W1 of the first tab 400 and the size W2 of the notch 120 satisfy: 1.5≤W2 / W1≤3.0.

[0093] This design helps control the size of the notch 120. On the one hand, it prevents the notch 120 from being too large, thus avoiding excessive capacity loss in the battery. On the other hand, it prevents the notch 120 from being too small, which would make it difficult to remove burrs from the edges of the notch 120. Furthermore, the width of the notch 120 is adapted to the width of the first tab 400, which allows the width of the notch 120 to be adapted to the width of the first insulating member 600, thereby helping to control the width difference of the slope region in the first direction.

[0094] Reference Figure 3 As shown, in some embodiments, along a third direction, the dimension W3 of the first insulating layer 610 and the dimension W2 of the notch 120 satisfy: 1.2 ≤ W2 / W3 ≤ 2. Along a third direction, the width W4 of the second insulating layer 620 and the dimension W2 of the notch 120 satisfy: 1 ​​≤ W4 / W2 ≤ 1.8.

[0095] It should be noted that, relatively speaking, the first insulating layer 610 is longer in the first direction and narrower in the third direction, while the second insulating layer 620 is shorter in the first direction and wider in the third direction, so as to achieve a better protective effect together. The width of the first insulating element 600 in the third direction and the width of the notch 120 in the third direction together determine the width of the slope area in the third direction.

[0096] Therefore, in specific implementation, W2 / W3 can be controlled between 1.2 and 2, so that the notch 120 is slightly wider than the first insulating layer 610, and W4 / W2 can be controlled between 1 and 1.8, so that the second insulating layer 620 is the same width as the notch 120, or the second insulating layer 620 is slightly wider than the notch 120. This ensures that after the first insulating layer 610 and the second insulating layer 620 are sequentially attached to the first electrode tab 400, the first insulating member 600 can completely cover the connection part between the first electrode tab 400 and the first current collector, and the width of the first insulating member 600 and the notch 120 in the third direction are matched, which helps to make the width of the slope area more uniform.

[0097] For example, W2 / W3 can be any one of the values ​​1.2, 1.5, 1.6, 1.8, or 2, or fall within the range of any two values. W4 / W2 can be any one of the values ​​1, 1.2, 1.4, 1.7, or 1.8, or fall within the range of any two values.

[0098] Reference Figures 5 to 7 As shown, in one possible implementation, the second electrode 300 includes a second active layer disposed on the surface of the first electrode 100 facing the first electrode tab 400. A first groove 310 is disposed on the second active layer. The electrode tab bundle is offset from the first groove 310. The first groove 310 is correspondingly disposed with the first electrode tab groove 110.

[0099] The orthographic projection of the first insulating layer 610 along the second direction is at least partially located in the first groove 310, and the orthographic projection of the second insulating layer 620 along the second direction is at least partially located in the first groove 310.

[0100] In this way, a portion of the first insulating layer 610 and a portion of the second insulating layer 620 can be accommodated within the first groove 310, thereby preventing the presence of the first insulating member 600 from increasing the local thickness of the battery too much, thus avoiding affecting the flatness of the battery and improving the energy density of the battery.

[0101] When attaching the first insulating layer 610 and the second insulating layer 620, the first insulating layer 610 can be attached to the first tab 400, and the second insulating layer 620 can be partially attached to the first groove 310.

[0102] The thickness of the first tab 400 is greater than the depth of the first tab groove 110, and there is a difference between the two. The ratio of the depth of the first groove 310 to this difference is between 1 and 2.5, so that the first groove 310 can effectively accommodate the thickness of the first tab 400 protruding from the first tab groove 110, thereby improving the flatness of the battery.

[0103] ReferenceFigure 8 As shown, in one possible implementation, the first tab 400 and the second tab 500 are located on the same side of the battery along the first direction. The battery also includes a second insulating member 700. The battery includes a first outer surface and a second outer surface disposed on the outermost side of the battery. The first outer surface and the second outer surface are disposed opposite to each other along the second direction.

[0104] The second insulating member 700 is disposed on the first outer surface and / or the second outer surface, and along the second direction, the orthographic projection of the second insulating member 700 at least partially overlaps with the orthographic projection of the notch 120.

[0105] Continue to refer to Figure 8 As shown, the second insulating member 700 may include one or both of the first sub-insulator 710 and the second sub-insulator 720. One end of the first sub-insulator 710 is connected to the first outer surface and extends along the thickness direction of the battery, such that the other end of the second sub-insulator 720 is connected to the second outer surface. Along the second direction, the orthographic projection of the first sub-insulator 710 overlaps with the orthographic projection of the notch 120. In this way, the first sub-insulator 710 can help fix the battery, thereby maintaining the stability of the slope region, which is beneficial for electrolyte storage and improving cycle performance.

[0106] The second sub-insulator 720 is attached to the first outer surface, or the second sub-insulator 720 is attached to the second outer surface, or the second sub-insulator 720 is attached to both the first and second outer surfaces, and along the second direction, the orthographic projection of the second sub-insulator 720 covers the orthographic projection of the notch 120.

[0107] Reference Figure 1 As shown, in some embodiments, the first electrode 100 has a first winding start end, the second electrode 300 has a second winding start end, the first electrode 100 has a first straight section, a first bent section and a second straight section located in the innermost circle of the battery, the end of the first straight section away from the first bent section is the first winding start end, the first bent section and the second winding start end are arranged opposite to each other, and the second winding start end and the first winding start end extend in opposite directions.

[0108] A third insulating element 800 is provided on the surface of the first bent section facing the second winding start end. And / or, the diaphragm 200 includes a diaphragm overhang portion extending beyond the second winding start end, the diaphragm overhang portion being folded back to form a folded section 210, the folded section 210 at least partially overlapping with the second electrode 300, and the dimension W5 of the overlapping portion along the third direction is 0.5mm-8mm.

[0109] The first electrode 100 is wound layer by layer starting from the first winding start end, and the second electrode 300 is wound layer by layer starting from the second winding start end. Folding the separator 200 back to wrap around the first winding start end can prevent the separator 200 from shrinking and exposing the first winding start end when the battery temperature rises too high, thereby avoiding contact between the first electrode 100 and the second electrode 300 and causing a short circuit. Furthermore, the third insulating member 800 is provided on the side of the first bending section opposite to the second winding start end to prevent the second winding start end from contacting the first bending section, thereby preventing lithium plating between the first electrode 100 and the second electrode 300 at this position, or preventing contact between the first electrode 100 and the second electrode 300 and causing a short circuit.

[0110] The battery preparation process of Example 1 of this application will be described below.

[0111] The battery preparation method of Embodiment 1 of this application includes:

[0112] I. Preparation of the first electrode 100 and the first electrode tab 400

[0113] A 9μm thick aluminum foil is used as the first current collector and the first tab 400.

[0114] Lithium cobalt oxide (LCO), polyvinylidene fluoride (PVDF), and conductive carbon (Super P) are dissolved in N-methylpyrrolidone (NMP) in a ratio of 97.5:1.5:1 and stirred evenly to form a slurry. The slurry is then uniformly coated on both surfaces of the first current collector to form the first active layer. After drying and rolling, the first electrode 100 is formed.

[0115] A first tab groove 110 is cleaned out on the first active layer of the first electrode 100, and a first tab 400 is welded to the first current collector. A first insulating member 600 is attached to the first tab 400. The width of the first electrode 100 is A. A notch 120 is provided on the opposite side of the first tab groove 110. The width of the first tab 400 is W1. The first distance between the first insulating member 600 and the notch 120 along the first direction is T. The length of the first insulating member 600 is L1. The depth dimension of the notch 120 along the first direction is M. The depth M of the notch 120 is between 0.3 mm and 15 mm. Wherein, T = A - L1 - M. For specific values, please refer to Table 1 below.

[0116] The value of T can be changed by altering the width A of the first electrode 100, the length L1 of the first insulating member 600, and the depth M of the notch 120.

[0117] II. Preparation of the second electrode 300 and the second electrode tab 500

[0118] A 6μm thick copper foil is used as the second current collector and the second tab 500. Silicon-carbon composite material, graphite, conductive carbon black, polyacrylic acid, sodium carboxymethyl cellulose, and styrene-butadiene rubber are mixed in a ratio of 43.1:53.8:0.5:1.3:0.4:0.9, and then mixed evenly with deionized water to form a slurry. This slurry is then uniformly coated onto both surfaces of the second current collector to form a second active layer. After drying and rolling, the second electrode sheet 300 is formed. Then, through die-cutting and slitting, multiple second tabs 500 are die-cut, resulting in an integral structure of multiple second tabs 500 and the second current collector. The number of second tabs 500 is greater than the number of first tabs 400. The second tabs 500 are welded to the adapter tabs.

[0119] III. Battery Assembly

[0120] The first electrode 100, separator 200 and second electrode 300 are stacked and wound in sequence, and then encapsulated, injected with liquid, sealed again, formed and sorted in sequence to obtain the battery. The thickness of the battery at the first tab 400 position is H1, and the second thickness of the battery at the notch 120 position is H2. For specific values, please refer to Table 1 below.

[0121] Wherein, the first spacing T is 3.6 times the width W1 of the first tab 400. The changes in structural parameters of Examples 2 to 11, Comparative Example 1, and Comparative Example 2 relative to Example 1 are shown in Table 1.

[0122] In Examples 1 to 8, 10 and 11, the first electrode 400 is a positive electrode, the second electrode 500 is a negative electrode, the first electrode 400 is a single electrode and is located in the middle of the length direction of the first electrode 100, and there are multiple second electrodes 500.

[0123] In Example 9, the first electrode tab 400 is a negative electrode tab, and the second electrode tab 500 is a positive electrode tab. The first electrode tab 400 is a single one and is located in the middle of the length direction of the first electrode plate 100. There are multiple second electrode tabs 500, and the second electrode tabs 500 are welded to the adapter tab.

[0124] In embodiment 5, the second electrode 300 is provided with a first groove 310, which can be used to accommodate part of the structure of the first insulating member 600.

[0125] In Embodiment 1, a first insulating layer 610 is attached to the first tab 400. In Embodiment 11, a first insulating layer 610 and a second insulating layer 620 are attached to the first tab 400.

[0126] In Comparative Example 2, there is one second tab, which is a centrally located structure. A 6μm thick copper foil is used as the second current collector. Silicon-carbon composite material, graphite, conductive carbon black, polyacrylic acid, sodium carboxymethyl cellulose, and styrene-butadiene rubber are mixed in a ratio of 43.1:53.8:0.5:1.3:0.4:0.9. After being mixed with deionized water to form a slurry, the slurry is uniformly coated on both surfaces of the second current collector to form a second active layer. After drying and rolling, a second electrode sheet 300 is formed. A second tab groove is cleaned out on the second active layer of the second electrode sheet 300. The second tab 500 is welded to the second current collector, and a fourth insulating component is attached to the second tab 500.

[0127] Table 1. Structural parameters of the battery

[0128]

[0129]

[0130] The specific test items and test methods are as follows:

[0131] I. Cyclic Performance:

[0132] Test method: The batteries obtained in the above examples and comparative examples were discharged at 25°C to 3V at 0.2C, fully charged according to the specifications (generally 2C), discharged at 0.2C 3 times, and the maximum capacity was taken as the initial discharge capacity at 0.2C; discharged at 0.2C to 3V, fully charged according to the specifications (generally 2C), discharged at 1C 3 times, and the maximum discharge capacity was taken as the initial capacity at 1C.

[0133] The cycle conditions are as follows: charge at a constant current of 18A to 4.3V (current cutoff, cutoff current 2C), then charge at a constant current of 2C to 4.45V (current cutoff, cutoff current 1.5C), then charge at a constant current of 1.5C to 4.53V (current cutoff, cutoff current 1.2C), and finally charge at a constant current of 1.2C to 4.58V (constant current cutoff, cutoff current 0.05C). Then discharge at 1C to 3V and record the discharged capacity as the capacity for this cycle. Rest for 5 minutes between each charge and discharge step.

[0134] The above cycle conditions are repeated 600 times. The discharge capacity of the 600th cycle is divided by the initial capacity and then multiplied by 100% to obtain the battery's 600T cycle capacity retention rate.

[0135] II. Fast charging performance

[0136] Test method: The batteries obtained in the above examples and comparative examples were discharged to 3V at 0.2C at 25°C, charged to 4.3V with a constant current of 18A (current cutoff, cutoff current 2C), charged to 4.45V with a constant current of 2C (current cutoff, cutoff current 1.5C), charged to 4.53V with a constant current of 1.5C (current cutoff, cutoff current 1.2C), and finally charged to 4.58V with a constant current of 1.2C (constant current cutoff, cutoff current 0.05C); then discharged to 3V at 0.5C and the discharged capacity was recorded as the initial capacity.

[0137] Test conditions: Charge at constant current 3C to full voltage 4.58V (constant current cut-off, cut-off current 0.02C); then discharge at 0.5C to 3V and record the discharged capacity as the capacity under this fast charging cycle. Let rest for 5 minutes between each charging and discharging step.

[0138] The ratio of initial capacity to fast charging capacity is a measure of fast charging performance.

[0139] III. Energy Density

[0140] The battery is charged to 4.5V at a current of 0.2C, then charged at a constant voltage until the current drops to 0.02C. It is then discharged at a current of 0.2C until it reaches 3.0V. The energy discharged is denoted as E. The battery's thickness, width, and length are measured, and their product is calculated to obtain the battery's volume, denoted as V. The formula for calculating the volumetric energy density VED is VED = E / V.

[0141] Table 2 Battery Test Results

[0142] Serial number 600T cycle capacity retention rate Fast charging performance Energy density (Wh / L) Example 1 86.67％ 88.98％ 756.8 Example 2 86.62％ 89.18％ 745.3 Example 3 86.55％ 89.25％ 739.2 Example 4 85.37％ 89.66％ 721.6 Example 5 87.96％ 90.18％ 763.8 Example 6 86.69％ 88.78％ 757.6 Example 7 86.45％ 88.69％ 755.7 Example 8 84.02％ 88.43％ 712.8 Example 9 86.02％ 84.35％ 736.4 Example 10 86.59％ 89.07％ 1025.6 Example 11 85.18％ 88.98％ 993.2 Comparative Example 1 82.15％ 87.98％ 717.9 Comparative Example 2 85.64％ 82.51％ 755.7

[0143] According to Tables 1 and 2 above, in Examples 1 to 11, when the first insulating member 600 covers the first tab 400, the first insulating member 600 and the notch 120 are disposed opposite to each other on both sides of the first electrode 100, and the first distance T between the first insulating member 600 and the notch 120 and the width W1 of the first tab 400 satisfy T / W1≥2, the cycle performance, fast charging performance and energy density of the battery can be improved.

[0144] Since the second electrode 300 of Embodiment 5 is provided with a first groove 310, it can be used to accommodate part of the structure of the first insulating member 600, thereby improving the energy density of the battery.

[0145] In Embodiment 11, a first insulating layer 610 and a second insulating layer 620 are attached to the first tab 400, which can improve the battery's safety, cycle performance and fast charging performance, but inevitably reduces the battery's energy density.

[0146] In Comparative Example 1, T is less than twice W1, there is one first tab 400 and multiple second tabs 500. The battery has low energy density, poor cycle performance, and average fast charging performance. This is because the electrolyte consumed by the first tab 400 cannot be replenished quickly, and the temperature rise of the first tab 400 is relatively fast, which reduces the cycle performance of the battery. The tab bundle formed by multiple second tabs 500 can basically meet the fast charging requirements of the battery, but it cannot simultaneously improve the fast charging performance, cycle performance, and energy density of the battery.

[0147] In Comparative Example 2, there is only one first tab 400 and one second tab 500. The first tab 400 is located in the middle of the length of the first electrode 100, and the second tab 500 is located in the middle of the length of the second electrode 300. This battery has a high energy density, average cycle performance, and poor fast charging performance. Comparing the two, it can be seen that the battery structure in Example 1 can effectively improve the fast charging performance of the battery.

[0148] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A battery, characterized by, The battery comprises: a first pole piece, a diaphragm and a second pole piece arranged in sequence, the polarities of the first pole piece and the second pole piece being opposite, the first pole piece comprising a first current collector, a first active layer and a notch, the second pole piece comprising a second current collector, the first active layer being provided with a first tab slot, the first tab slot and the notch being oppositely arranged along a first direction; a first tab, at least a part of the first tab being arranged in the first tab slot and connected with the first current collector; a plurality of second tabs, the plurality of second tabs being electrically connected with the second current collector, the plurality of second tabs being arranged in layers and connected with each other to form a tab bundle; a first insulating member, a projection of the first insulating member at least partially covering the first tab along a second direction; a width of the first tab along a third direction being W1, a first interval of the first insulating member and the notch along the first direction being T, the T being greater than or equal to 2 times the W1; wherein the second direction is along a thickness direction of the battery, the first direction, the second direction and the third direction being perpendicular to each other in pairs.

2. The battery of claim 1, wherein the second tab being integrally formed with the corresponding second current collector, the number of the second tabs being greater than the number of the first tabs; a length of the first insulating member along the first direction being L1, the L1 being less than or equal to the first interval T.

3. The battery according to claim 1 or 2, characterized in that the T satisfying: 20mm≤T≤100mm; and / or, the L1 and the T satisfying: 1≤T / L1≤7.

5.

4. The battery according to claim 1 or 2, characterized by the first insulating member comprising a first insulating layer and a second insulating layer, the first insulating layer being arranged on a surface of the first tab, the second insulating layer being arranged on a surface of the first insulating layer away from the first tab; a projection of the first insulating layer at least partially covering a partial area of the first tab slot along the second direction, a projection of the second insulating layer at least partially covering a partial area of the first tab slot, the projection of the first insulating layer and the projection of the second insulating layer being partially overlapped and partially staggered; and / or, the first insulating layer being arranged closer to the notch relative to the second insulating layer along the first direction.

5. The battery of claim 3, wherein, the battery having a first thickness H1 and a second thickness H2, the first thickness H1 corresponding to a position where the first tab is located, the second thickness H2 corresponding to a position where the notch is located; the first thickness H1 and the second thickness H2 satisfying: 20μm≤H1-H2≤100μm.

6. The battery according to claim 1 or 2, characterized by a projection of the first tab slot being located within a projection of the notch along the first direction; and / or, a size W1 of the first tab and a size W2 of the notch along the third direction satisfying: 1.5≤W2 / W1≤3.

0.

7. The battery of claim 4, wherein, a size W3 of the first insulating layer and the size W2 of the notch along the third direction satisfying: 1.2≤W2 / W3≤2; and / or, a width W4 of the second insulating layer and the size W2 of the notch along the third direction satisfying: 1≤W4 / W2≤1.

8.

8. The battery of claim 4, wherein, The second tab includes a second active layer arranged on a side surface of the first tab facing the first tab, and a first groove is arranged on the second active layer, the tab bundle is arranged away from the first groove, and the first groove and the first tab groove are arranged in correspondence along the second direction; The first insulating layer is at least partially projected on the first groove along the second direction, and the second insulating layer is at least partially projected on the first groove along the second direction.

9. The battery according to claim 1 or 2, characterized by The first tab and the second tab are located on the same side of the battery along the first direction, and the battery further includes a second insulating member, the battery includes a first outer surface and a second outer surface arranged on the outermost side of the battery, and the first outer surface and the second outer surface are oppositely arranged along the second direction. The second insulating member is arranged on the first outer surface and / or the second outer surface, and the second insulating member is at least partially overlapped with the projection of the notch along the second direction.

10. The battery according to claim 1 or 2, characterized by The first tab is a positive tab, the second tab is a negative tab, the first tab has a first winding starting end, the second tab has a second winding starting end, the first tab has a first flat section, a first bending section and a second flat section located on the innermost circle of the battery, one end of the first flat section away from the first bending section is the first winding starting end, the first bending section is arranged opposite to the second winding starting end, the second winding starting end extends in a direction opposite to the first winding starting end, the second tab includes a second active layer, and the second active layer includes a silicon-based material. The first bending section is provided with a third insulating member on a side surface facing the second winding starting end; and / or, the separator includes a separator excess portion beyond the second winding starting end, the separator excess portion is folded to form a folding section, the folding section at least partially overlaps with the second tab, and the size of the overlapping portion along the third direction is 0.5mm-8mm.

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