Electrode plate, battery cell and battery

Abstract

The utility model provides an electrode plate, a battery cell and a battery. The electrode plate comprises a current collector, a safe priming coat, an active layer and a tab, the current collector comprises a first region and a second region; the first area is provided with X concave part structures, X is greater than or equal to 1, the safety bottom coating is arranged on at least part of the functional surface of the first area and at least part of the concave part structures, and the active layer is arranged on the surface, far away from the current collector, of the safety bottom coating; the first plane is parallel to the functional surface of the current collector, the orthographic projection area of the second region on the first plane is S2, the orthographic projection area of the first region on the first plane is S1, and 100 mm < 2 > lt is satisfied; s2lt; s1; and the tab is arranged on the functional surface of the second area. The problems of short circuit caused by exposure of a current collector fracture surface and insufficient tab welding tension in the prior art can be solved, so that the safety performance of the battery is further improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of secondary batteries, and specifically relates to an electrode sheet, a battery core and a battery. Background Art

[0002] The wide application of lithium-ion batteries in many fields such as electronic products, power vehicles and energy storage has greatly improved people's social life and production. With the advancement of technology, people have continuously put forward higher requirements for the safety performance of lithium-ion batteries.

[0003] However, the short-circuit problem caused by the exposure of the functional surface of the current collector and the reduced welding tension of the pole ear and the loose welding can easily cause short-circuit or open-circuit problems in the battery, which will further cause safety accidents such as battery explosion or fire, and are not conducive to improving the safety performance of the battery.

[0004] Therefore, how to further improve the safety performance of batteries is a technical problem that needs to be urgently solved in this field. Utility Model Content

[0005] The utility model provides an electrode sheet to solve the problems of the current collector functional surface exposure and the insufficient electrode ear welding tension in the prior art, thereby further improving the safety performance of the battery.

[0006] The utility model also provides a battery cell, which includes the electrode sheet and can effectively avoid short-circuit contact caused by insufficient welding tension of the tab, thereby improving the safety performance of the battery.

[0007] The utility model also provides a battery, which has excellent performance in safety performance and the like, has firm welding of the tabs, and has a higher pass rate in mechanical abuse tests, such as a screw extrusion test and a heavy object impact test.

[0008] The utility model provides an electrode sheet, comprising a current collector, a safety bottom coating, an active layer and a pole ear;

[0009] The current collector includes a first region and a second region; the first region is provided with X concave structures, X≥1,

[0010] The safety primer layer is disposed in at least part of the functional surface of the first region and at least part of the concave structure, and the active layer is disposed on the surface of the safety primer layer away from the current collector;

[0011] The area of ​​the second region is S2, the area of ​​the first region is S1, and the area of ​​the second region is 100 mm2. <S2<S1;

[0012] The electrode tab is disposed on the functional surface of the second region and is electrically connected to the current collector.

[0013] The electrode sheet as described above is a positive electrode sheet.

[0014] For the electrode sheet as described above, S1 and S2 satisfy that S1 / S2 is 1-150.

[0015] In the electrode sheet as described above, active layers are provided on at least two sides of the electrode tab.

[0016] In the electrode sheet as described above, the second region is adjacent to the first region at both ends in the length direction of the current collector; in the width direction of the current collector, the size of the first region is W1, the size of the second region is W2, and 0.2≤W2 / W1≤1.

[0017] In the electrode sheet as described above, the first region and the second region are alternately distributed in the width direction of the current collector, and the second region is located on at least one side of the current collector in the width direction.

[0018] The electrode sheet as described above includes M second regions and N electrode tabs, 1≤N, 1≤M.

[0019] In the electrode sheet as described above, the orthographic projection area of ​​each pole tab in the second region is at least 30% of the area of ​​the pole tab; or, the ratio of the orthographic projection area of ​​each pole tab in the second region to the area of ​​the second region is 1-95%.

[0020] For the electrode sheet as described above, the orthographic projection area of ​​the concave structure in the first region on the first plane is S21, S21 / S2×100%=5%-50%, and the first plane is parallel to the functional surface of the current collector; and / or,

[0021] The depth of the recessed structure is d1, the thickness of the current collector is d2, wherein 1 / 3≤d1 / d2≤1; and / or the size of the opening end of the recessed structure is L1, and the center line spacing between adjacent recesses is L2, wherein 1≤L2 / L1≤10.

[0022] In the electrode sheet as described above, L1 is 10 to 300 μm; and / or L2 is 10 to 10000 μm, and / or d1 is 1 to 10 μm, and / or d2 is 3 to 15 μm.

[0023] In another aspect, the utility model provides a battery core, comprising the electrode sheet as described above.

[0024] The battery cell as described above is a wound battery cell, and the opening end of the recessed structure in the first region of the electrode sheet faces a side away from the center of the battery cell.

[0025] In another aspect, the utility model provides a battery, comprising the battery cell as described above.

[0026] The implementation of the present utility model has at least the following beneficial effects:

[0027] For the positive electrode sheet provided by the present utility model, by providing a safety bottom coating and defining that the orthographic projection areas S2 and S1 of the second region and the first region on the first plane satisfy 100 mm 2 <S2 < S1. On the one hand, it can increase the contact area between the safety bottom coating and the current collector, enabling a better bonding effect between the safety bottom coating and the current collector, increasing the difficulty of peeling of the safety bottom coating, preventing the functional surface of the current collector from being exposed, and avoiding short-circuit problems caused by the exposure of the functional surface of the current collector; the tab is arranged in the second region, ensuring good welding tensile force between the tab and the current collector, ensuring firm tab welding, and avoiding problems such as short circuit or open circuit during the charge and discharge cycle of the battery due to insecure tab welding. Therefore, the present utility model can improve the safety performance of the battery by preventing the exposure of the functional surface of the current collector and enhancing the tab welding strength. Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions of the present utility model, the following will briefly introduce the drawings required for the description of the embodiments of the present utility model. Obviously, the following drawings are some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0029] Figure 1 is a schematic cross-sectional structure diagram of an electrode sheet in an embodiment of the present utility model;

[0030] Figure 2 is a top view schematic diagram of the connection structure of the current collector and the tab in an electrode sheet in an embodiment of the present utility model;

[0031] Figure 3 is a top view schematic diagram of the connection structure of the current collector and the tab in an electrode sheet in another embodiment of the present utility model;

[0032] Figure 4 is a top view schematic diagram of the connection structure of the current collector and the tab in an electrode sheet in yet another embodiment of the present utility model;

[0033] Figure 5 is a top view schematic diagram of the connection structure of the current collector and the tab in yet another embodiment of the present utility model;

[0034] Figure 6 is a top view schematic diagram of the first region in the current collector of an electrode sheet in an embodiment of the present utility model;

[0035] Figure 7is a schematic cross-sectional structure diagram of the first region of the current collector in the electrode sheet along the Figure 6 dashed line in

[0036] Figure 8 is a schematic cross-sectional structure diagram of the first region of the current collector in the electrode sheet along the Figure 6 dashed line in

[0037] Description of reference numerals:

[0038] 1 - Current collector; 11 - First region; 12 - Second region; 2 - Safety bottom coating; 3 - Active layer; 4 - Tab; 1101 - Recess structure. Detailed implementation manners

[0039] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] In the description of the present invention, "arrangement" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection, etc.; for those of ordinary skill in the art, the specific meaning of the above terms in the present invention can be understood according to specific circumstances. Terms such as "first" and "second" are only used for descriptive purposes, for example, to distinguish each component to more clearly illustrate / explain the technical solution.

[0041] Figures 1 to 8 Among them, the X direction is the length direction of the current collector 1, the Y direction is the width direction of the current collector 1, and the Z direction is the thickness direction of the current collector 1.

[0042] On the one hand, the present invention provides an electrode sheet, as Figure 1 shown, including a current collector 1, a safety bottom coating 2, an active layer 3, and a tab 4; the current collector 1 includes a first region 11 and a second region 12; the first region 11 is provided with X recess structures 1101, X≥1, the safety bottom coating 2 is arranged on at least part of the functional surface of the first region 11 and at least part of the recess structures 1101, the active layer 3 is arranged on the surface of the safety bottom coating 2 away from the current collector 1; the area of the second region 12 is S2, and the area of the first region 11 is S1, satisfying 100mm 2 <S2 < S1; the tab 4 is arranged on the functional surface of the second region 12 and is electrically connected to the current collector 1.

[0043] The electrode sheet in the utility model can be a positive electrode sheet or a negative electrode sheet.

[0044] When the electrode sheet is a positive electrode sheet, the current collector 1 may be an aluminum foil, an aluminum-coated film composite current collector, etc. When the electrode sheet is a negative electrode sheet, the current collector 1 may be a copper foil.

[0045] The current collector 1 has two largest and opposite functional surfaces, and the safety primer layer 2 is disposed on at least part of the functional surface of the first region 11 and in at least part of the recessed structure 1101 .

[0046] In the utility model, the safety bottom coating 2 contains functional materials, and the functional materials include at least one of inorganic materials and organic materials. Among them, the inorganic material includes at least one of metal oxides, non-metallic oxides, and inorganic salts, such as lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium phosphate, lithium manganese-rich material, lithium nickel cobalt aluminum oxide, lithium titanate, aluminum oxide, boehmite, titanium dioxide, zirconium oxide, zinc oxide, silicon dioxide, silicon carbide, and silicon nitride. The organic material includes at least one of polyethylene, polypropylene, polystyrene, polymethyl methacrylate, polytetrafluoroethylene, polyaniline, polypyrrole, and polythiophene, so as to ensure that the above-mentioned functional material particles can reduce the probability of short circuit while not affecting the transfer of lithium ions.

[0047] The safety bottom coating 2 also includes an adhesive, which includes one or more of polyvinylidene fluoride (PVDF), acrylic acid-modified PVDF, polyacrylate polymers, polyimide, styrene-butadiene rubber, styrene-acrylic rubber, and PAA, so as to ensure that the safety bottom coating 2 is fixedly bonded to the current collector 1 .

[0048] The active layer 3 is arranged on the surface of the safety base coating 2 away from the current collector 1. At this time, the safety base coating 2 is located between the current collector 1 and the active layer 3. The active layer 3 is used for redox reaction to realize the storage and release of battery energy.

[0049] When the electrode sheet is a positive electrode sheet, the material of the active layer 3 may include at least one of a ternary material, lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium phosphate, lithium manganese-rich based material, and lithium nickel cobalt aluminum oxide; when the electrode sheet is a negative electrode sheet, the material of the active layer 3 may be selected from graphite, silicon-based, hard carbon, soft carbon, and other negative electrode active materials.

[0050] In addition, the safety bottom coating 2 and the active layer 3 each independently contain a conductive agent, which includes at least one of conductive carbon black, acetylene black, graphite, graphene, carbon nanotubes, carbon nanofibers, conductive polythiophene, conductive polypyrrole, and conductive polyaniline. In this way, while ensuring the reduction of the possibility of short circuit, a good conductive network is imparted to the safety bottom coating 2 and the active layer 3, which can ensure smooth electron conduction between the first coating, the second coating and the current collector 1, so that the battery has excellent safety performance and good cycling performance at the same time.

[0051] The current collector 1 is divided into a first region 11 and a second region 12 according to whether it contains the concave structure 1101. Among them, the first region 11 is provided with the concave structure 1101, and the second region 12 is not provided with the concave structure 1101. Exemplarily, when the current collector 1 is an aluminum foil, the first region 11 is a heterogeneous foil in which the concave structure 1101 and the homogeneous foil are alternately arranged, and the second region 12 is a homogeneous foil without the concave structure 1101.

[0052] As Figures 2 to 5 shown, the first region 11 and the second region 12 are one or more. A plurality of first regions 11 and a plurality of second regions 12 are arranged in sequence in the extending direction of the current collector 1, as long as the first region 11 and the second region 12 are included.

[0053] The area S2 of the second region 12 and the area S1 of the first region 11 respectively refer to: under the incident light parallel to the thickness direction of the current collector 1, the projected areas of the second region 12 and the first region 11 on the first plane. The first plane is a plane parallel to the functional surface of the current collector 1. Among them, S1 and S2 satisfy 100 mm 2 < S2 < S1. This ensures that there is enough first region 11 to prevent the defect of the fracture surface of the current collector 1 from being exposed, and at the same time ensures that there is enough second region 12 to realize the setting of the tab 4, maximizing the safety performance and ensuring the loading capacity.

[0054] Among them, S1 and S2 satisfy 100 mm 2 < S2 < S1, which can also be understood as S2 / S1 < 1, and S1, S2 > 100 mm 2 .

[0055] Preferably, it satisfies: 200 mm 2 < S2 < S1, which can also be understood as S2 / S1 < 1, and S2, S1 > 200 mm 2 .

[0056] The concave structure 1101 is arranged in the first region 11. Correspondingly, the open end of the concave structure 1101 communicates with the first functional surface or the second functional surface.

[0057] The number of the recessed structures 1101 is one or more. When the number of the recessed structures 1101 is multiple, the multiple recessed structures 1101 are spaced apart in the extension direction of the current collector 1. It can also be understood that under incident light parallel to the thickness direction of the current collector 1, the projections of any two recessed structures 1101 on the first plane are independent of each other without any overlapping or covering relationship. For example, the multiple recessed structures 1101 are distributed in a linear array in the length direction or width direction of the current collector 1.

[0058] The aperture of the recessed structure 1101 may be constant or gradually change along the thickness direction of the current collector 1. It should be noted that when the aperture of the recessed structure 1101 is constant along the thickness direction of the current collector 1, the aperture of the recessed structure 1101 is the diameter of the recessed structure 1101, and the open end of the recessed structure 1101 is any end connected to the functional surface; when the aperture of the recessed structure 1101 is gradually changed along the thickness direction of the current collector 1, the open end of the recessed structure 1101 refers to the large-mouth end (i.e., the end with a larger diameter).

[0059] For example, in one embodiment, when the aperture of the recess structure 1101 gradually decreases along the direction from the first functional surface to the second functional surface, the opening end of the recess structure 1101 refers to the aperture of the recess structure 1101 on the first functional surface; in another embodiment, when the aperture of the recess structure 1101 gradually decreases along the direction from the second functional surface to the first functional surface, the aperture of the opening end of the recess structure 1101 refers to the aperture of the recess structure 1101 on the second functional surface.

[0060] Specifically, on the side where the recessed structure 1101 is provided in the thickness direction of the current collector 1, it can be observed that the shape of the recessed structure 1101 may be circular (eg Figure 6 As shown), annular, elliptical, triangular, square, rhombus, etc.; the hole cross-section of the recessed structure 1101 is triangular, trapezoidal, square, arc, etc.

[0061] The utility model can avoid safety problems caused by battery short circuit by setting a safety bottom coating on the inner surface of the cavity formed by the recessed structure 1101. The reason is that when the pole piece is applied to the battery, when the battery is damaged by external force and deformed or broken inward, the opening end of the recessed structure 1101 is located on the functional surface of the current collector 1, making it easier for the current collector 1 to be broken at the recessed structure 1101. At this time, the recessed safety coating covering the recessed structure 1101 can slide and spread inward in the direction of damage, so that the fracture surface of the current collector 1 is covered and protected by the recessed safety coating, so that it is not exposed, and the resistance when the positive and negative electrodes are in contact with each other is increased, effectively reducing the short-circuit current, thereby improving the safety performance of the battery.

[0062] The tab 4 is arranged on the functional surface of the second region 12, and the electrical connection can be achieved by laser welding or ultrasonic welding. Due to the arrangement of the recessed structure 1101, the mechanical strength of the first region 11 is weaker than that of the second region 12. By arranging the tab 4 in the second region 12 with relatively high mechanical strength, the welding tension of the tab 4 can be increased, and the welding strength can be enhanced. In addition, the second region 12 is a homogeneous current collector, and the thickness of the overall welding area is consistent, which can ensure the consistency of the connection area formed by welding, prevent short circuit, and thus improve the safety performance of the battery.

[0063] Furthermore, in a specific embodiment of the present invention, the electrode sheet is a positive electrode sheet.

[0064] Further, in a specific embodiment of the present invention, the area S2 of the second region and the area S1 of the first region satisfy that S2 / S1 is 1-150.

[0065] By further limiting S2 / S1 to 1-150, while ensuring the welding tension of the pole tab 4, the distribution range of the first area 11 outside the pole tab 4 is maximized, allowing the electrolyte to flow freely therein, promoting the transmission of lithium ions and improving the cycle life of the battery.

[0066] Further, in a specific embodiment of the present invention, Figure 1 As shown, active layers 3 are provided on at least two sides of the pole tab 4 .

[0067] Active layers 3 are arranged on at least two sides of the tab 4, that is, the electrode sheet adopts a tab-centered structure.

[0068] In detail, Figure 1 As shown, in the length direction of the current collector 1, the pole lug 4 is arranged between two adjacent active layers 3, that is, the pole lug 4 is located at the non-end of the electrode sheet. It can be understood that when the pole lug 4 is arranged between two adjacent active layers 3, the pole lug 4 is also arranged between two adjacent safety primer layers 2. Among them, adjacent refers to the relationship of being connected to each other or close to each other.

[0069] Further, in a specific embodiment of the present invention, Figure 2 and Figure 3 As shown, the second region 12 is adjacent to the first region 11 at both ends in the length direction of the current collector 1 , and in the width direction of the current collector 1 , the size of the first region 11 is W1 , the size of the second region 12 is W2 , and 0.2≤W2 / W1≤1.

[0070] At this time, the tabs 4 are stacked on the functional surface of the second region 12 and extend along the width direction of the current collector 1 beyond the edge of the current collector 1 in the length direction, so as to facilitate the extraction of current.

[0071] When W2 / W1 = 1, that is, in the width direction of the current collector 1 , the size of the first region 11 is the same as the size of the second region 12 .

[0072] like Figure 3 As shown, the current collector 1 includes a first region 11, a second region 12 and a first region connected in sequence along the length direction. The tab 4 is arranged in the second region 12. At this time, the two first regions are not connected, that is, in the length direction of the current collector 1, the second region 12 separates the two first regions 11, and the two opposite ends of the second region 12 in the width direction of the current collector 1 are respectively connected to the first region 11. At this time, the sizes of the first region 11 and the second region 12 in the width direction of the current collector 1 are consistent with the sizes of the current collector 1 in the width direction.

[0073] When 0.2≤W2 / W1<1, that is, in the width direction of the current collector 1, the size of the second region 12 is smaller than that of the first region 11.

[0074] like Figure 2 As shown, the two opposite ends of the second region 12 in the width direction of the current collector 1 are respectively connected to the first region 11, and the first region 11 and the second region 12 are connected to one end of the second region 12 in the length direction of the current collector 1, and the other end of the second region 12 is flush with the edge of the current collector. At this time, the size of the second region 12 in the width direction of the current collector 1 is smaller than the size of the first region 11 in the width direction.

[0075] When the size relationship between the first region 11 and the second region 12 satisfies the above range, it can not only ensure that the pole piece has strong mechanical strength and reduce the risk of pole piece breakage, but also enable the pole piece to break from the recessed structure of the first region when damaged by external force, thereby reducing the probability of short circuit at the fracture of the current collector and improving the safety of the battery.

[0076] Further, in a specific embodiment of the present invention, Figure 4 , Figure 5 As shown, the first region 11 and the second region 12 are alternately distributed in the width direction of the current collector 1 , and the second region 12 is located on at least one side of the current collector 1 in the width direction.

[0077] The present invention does not limit the specific number of times that the first region 11 and the second region 12 are alternately distributed in the width direction of the current collector 1 , as long as the second region 12 is located on at least one side of the current collector 1 in the width direction.

[0078] In detail, Figure 4As shown, the current collector 1 includes a first region 11 and a second region 12 connected in sequence along the width direction. At this time, the second region 12 is only located on one side of the current collector 1 in the width direction, and the electrode tab 4 is arranged in the second region 12 .

[0079] In another specific embodiment, Figure 5 As shown, when the current collector 1 includes a second region 12 , a first region 11 and a second region 12 connected in sequence along the width direction, the second region 12 is located on both sides of the current collector 1 in the width direction, and the tab 4 is arranged on any second region 12 .

[0080] Furthermore, in a specific embodiment of the present invention, the electrode sheet includes M second regions 12 and N electrode tabs 4, 1≤N, 1≤M.

[0081] In detail, the electrode sheet may include no less than one second region 12 and no less than one electrode tab 4 .

[0082] The present invention does not limit the relationship between the number N of the tabs 4 and the number M of the second regions 12. One tab may be provided in one second region 12, or a plurality of tabs may be provided in one second region 12.

[0083] When a multi-electrode design is adopted, the internal resistance of the electrode sheet can be effectively reduced, the conductivity of the battery can be improved, and the structural stability of the substrate can be enhanced, reducing the risk of deformation and displacement of the electrode sheet during the use of the battery.

[0084] Furthermore, in a specific embodiment of the present invention, the projection area of ​​each pole lug 4 in the second region 12 is at least 30% of the area of ​​the pole lug 4; or, the ratio of the projection area of ​​each pole lug 4 in the second region 12 to the area of ​​the second region 12 is 1-95%.

[0085] The projected area of ​​each electrode tab 4 on the second region 12 refers to the area of ​​the overlapping portion between the electrode tab 4 and the second region 12 when the electrode tab 4 is connected to the second region 12 by laser welding or ultrasonic welding.

[0086] The area of ​​the tab 4 refers to the total area of ​​the plane parallel to the tab 4 and the second region 12 .

[0087] When the projection area of ​​each pole lug 4 in the second region 12 is at least 30% of the area of ​​the pole lug 4, it can not only ensure a good welding effect and improve the welding tension, but also enable the pole lug to better exert its conductivity and ensure that the pole lug has a larger current carrying capacity and structural stability.

[0088] Specifically, the ratio of the projected area of ​​each pole ear 4 on the second region 12 to the area of ​​the second region 12 is 1-95%. On the one hand, a certain blank margin is reserved for the pole ear welding to facilitate the process, and on the other hand, the welding stability is guaranteed and the welding tension is improved.

[0089] It can be understood that there may be multiple pole ears 4 and multiple second areas 12 in the electrode sheet. Here, only the area relationship between each pole ear 4 and the second area 12 where each pole ear 4 is located and the relationship between the projected area of ​​each pole ear 4 in the second area 12 and its own area are defined.

[0090] Further, in a specific embodiment of the present invention, the orthographic projection area of ​​the recess structure in the first region on the first plane is S21, wherein S21 / S1×100%=5%~50%, and the first plane is parallel to the functional surface of the current collector; and / or, the depth of the recess structure is d1, and the thickness of the current collector is d2, wherein 1 / 3≤d1 / d2≤1; and / or, the opening end size of the recess structure is L1, and the center line spacing between adjacent recesses is L2, wherein 1≤L2 / L1≤10.

[0091] Specifically, the orthographic projection area of ​​the concave structure 1101 in the first region 11 on the first plane is S21, and the orthographic projection area of ​​the first region 11 on the first plane is S1, wherein S21 / S1×100%=5% to 50%. For example, S21 / S1×100% includes but is not limited to 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% or any range between two of them. By limiting the proportion of the concave structure 1101, it is prevented that the concave structure 1101 in the first region 11 is too dense to affect the mechanical strength of the first region 11. At the same time, it is prevented that the concave structure 1101 in the first region 11 is too sparse to play a role in improving safety performance and promoting lithium ion transmission. In addition, the energy density of the battery can be ensured.

[0092] The depth of the recessed structure 1101 is d1, and the thickness of the current collector 1 is d2, which satisfies: 1 / 3≤d1 / d2≤1. The depth of the recessed structure 1101 is the dimension of the recessed structure 1101 in the thickness direction of the current collector 1. When d1 / d2=1, Figure 8 As shown, at this time, the depth of the recessed structure 1101 is consistent with the thickness of the current collector 1, and the recessed structure 1101 is a through hole; when 1 / 3≤d1 / d2<1, as Figure 7 As shown, the recessed structure 1101 is a blind hole, that is, it does not penetrate the current collector 1 in the thickness direction of the current collector 1 .

[0093] The aperture L1 of the opening end of the recessed structure 1101 and the centerline spacing of adjacent recessed structures 1101 satisfy the following relationship: 1≤L2 / L1≤10; wherein, the centerline spacing of adjacent recessed structures 1101 can also be understood as the sum of the distance between two adjacent recessed structures 1101 and the radius of the opening ends of two adjacent recessed structures 1101. By defining the relationship between L1 and L2, it is possible to avoid the problem of the recessed structure being too dense or too sparsely arranged, which leads to the inability to improve safety, ensure that the recessed structure is dominant, and enable the current collector to retain a certain mechanical strength to meet the needs of the process, while giving full play to the advantages of the recessed structure to make the battery have better safety.

[0094] Further, in a specific embodiment of the present invention, L1 is 10 to 300 μm; and / or L2 is 10 to 10000 μm, and / or d1 is 1 to 10 μm, and / or d2 is 3 to 15 μm.

[0095] L1 is 10 to 300 μm, for example, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 200 μm, 300 μm or a range consisting of any two thereof; L2 is 10 to 10000 μm, for example, 10 μm, 20 μm, 30 μm, 50 μm, 100 μm, 200 μm, 300 μm, 500 μm m, 1000μm, 2000μm, 5000μm, 10000μm or a range consisting of any two of them; d1 is 1-10μm, for example, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 8μm, 10μm or a range consisting of any two of them; d2 is 3-15μm, for example, 3μm, 4μm, 5μm, 10μm, 12μm, 15μm or a range consisting of any two of them.

[0096] In another aspect, the utility model provides a battery core, comprising the electrode sheet as described above.

[0097] It should be noted that the battery cell provided by the present invention is preferably applicable to lithium-ion batteries; of course, it is also applicable to sodium-ion batteries and other battery cells, and no excessive limitations are made here.

[0098] The battery cell of the present invention further includes a negative electrode sheet and a separator, and the separator is used to separate the positive electrode sheet and the negative electrode sheet to avoid direct contact between the positive electrode sheet and the negative electrode sheet. The battery cell can be a winding structure, a laminated structure, etc., and the present invention does not make too many restrictions here. Specifically, the battery cell can be a winding structure formed by stacking and winding a positive electrode sheet, a separator and a negative electrode sheet, or a laminated structure formed by stacking a plurality of positive electrode sheets, separators and negative electrode sheets in sequence.

[0099] Since the battery cell of the utility model comprises the pole piece as described above, the battery cell has excellent safety performance.

[0100] Further, in a specific embodiment of the present invention, the battery cell is a wound battery cell. The opening end of the concave structure 1101 in the first region 11 of the electrode sheet faces a side away from the center of the battery cell.

[0101] The opening end of the recessed structure 1101 faces the side away from the center of the battery cell, that is, the opening end of the recessed structure 1101 faces the outside of the battery cell. In this way, when the battery cell is damaged by external force and causes inward deformation or fracture, the recessed safety coating covering the inner surface of the recessed structure 1101 can slide and spread inward in the direction of destruction, effectively protecting the fracture surface of the current collector 1 from exposure, thereby avoiding short circuit problems caused by the exposure of the fracture surface of the current collector 1.

[0102] In another aspect, the utility model provides a battery, comprising the battery cell as described above.

[0103] The battery of the present invention is preferably a lithium-ion secondary battery, including but not limited to a soft-pack battery, a square battery, a cylindrical battery, and the like.

[0104] By installing the battery core and the protection circuit together inside the aluminum-plastic film, a battery for charging / discharging can be formed. The quality of the battery core directly determines the quality of the battery. Due to the use of the above-mentioned pole piece, the battery of the utility model has excellent performance in safety performance and other aspects.

[0105] The above-mentioned battery also includes an electrolyte. Specifically, the electrolyte is injected into the battery cell after packaging, and the battery is manufactured through processes such as formation, capacity separation, and OCV.

[0106] The present invention will be further described below through specific embodiments.

[0107] Example 1

[0108] 1. Preparation of positive electrode

[0109] (1) Punching: A laser punching method is used to punch holes at the first region 11 of the first functional surface of the aluminum foil to form a concave structure 1101, where the concave structure 1101 is a through hole. Figure 2 The current collector 1 shown in the figure; wherein the orthographic projection area of ​​the second region on the first plane is S2, the orthographic projection area of ​​the first region 11 on the first plane is S1, and the orthographic projection area of ​​the concave structure 1101 on the first plane is S21, satisfying: S2 / S1=1 / 149; S2=660mm 2 (22*30mm), the area of ​​positive electrode collector 1 is 99000mm 2(1100*90mm), S1=98340mm 2 , S21 / S1×100%=30%.

[0110] (2) Preparation of safety primer coating slurry: boehmite, carbon black, polyacrylate and N-methylpyrrolidone (NMP) were mixed, the solid content of the slurry was adjusted to 40%, and the slurry was stirred evenly to obtain a safety primer coating slurry; wherein the mass ratio of boehmite, carbon black and polyacrylate was 95:5:5;

[0111] Preparation of positive electrode active layer slurry: lithium cobalt oxide (LCO), carbon black, carbon nanotubes, polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) are mixed, the solid content of the slurry is adjusted to 70%, and the positive electrode active layer slurry is obtained after uniform stirring; wherein the mass ratio of LCO, carbon black, carbon nanotubes and PVDF is 96:1:1:2.

[0112] (3) coating the safety primer slurry in step (2) on the functional surface of the positive electrode current collector 1 in step (1), drying it, and then coating the positive electrode active layer slurry in step (2) on the surface of the safety primer slurry, and drying it to obtain an initial positive electrode film

[0113] (4) After rolling and cutting the initial positive electrode film, Figure 2 The position shown is to weld the positive electrode tab 4 at the preset position of the second region 12, the projection area of ​​the tab in the second region accounts for 50% of the maximum area of ​​the tab, and the ratio of the projection area of ​​the tab in the second region to the area of ​​the first region is 90%, thereby obtaining a positive electrode sheet.

[0114] 2. Preparation of negative electrode sheet

[0115] Artificial graphite, carbon black, styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC) and deionized water in a mass ratio of 96:1:1.5:1.5 are mixed, the solid content of the slurry is adjusted to 40%, and after being stirred evenly, a negative electrode coating slurry is obtained;

[0116] The negative electrode coating slurry is coated on the surface of the negative electrode current collector, and the negative electrode sheet is obtained after drying, rolling and cutting.

[0117] 3. Preparation of batteries

[0118] The positive electrode sheet, the separator, and the negative electrode sheet are stacked and wound in sequence to obtain a winding core; wherein the opening end of the concave structure 1101 faces a side away from the center of the winding core;

[0119] Use a punching die to punch out the aluminum-plastic film, then use the punched aluminum-plastic film to package the roll core to obtain the battery cell, bake it until the moisture content is qualified, and inject the electrolyte; use lithium-ion battery formation equipment to charge and discharge the battery cell to harden the battery cell and sort out the capacity of the battery cell; perform a secondary sealing on the battery cell and fold the edge to form the battery cell, and perform an OCV test to test the K value of the battery, select the products with qualified K value, and obtain the lithium-ion battery.

[0120] Example 1-1

[0121] The preparation process of this embodiment is basically the same as that of embodiment 1, except that: in the preparation of the positive electrode sheet, the distribution of the concave structure in the first region is adjusted so that S21 / S1×100%=5%, and other conditions remain unchanged to obtain the positive electrode sheet of this embodiment;

[0122] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example.

[0123] Example 1-2

[0124] The preparation process of this embodiment is basically the same as that of embodiment 1, except that: in the preparation of the positive electrode sheet, the distribution of the concave structure in the first region is adjusted so that S21 / S1×100%=20%, and other conditions remain unchanged to obtain the positive electrode sheet of this embodiment;

[0125] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example.

[0126] Examples 1-3

[0127] The preparation process of this embodiment is basically the same as that of embodiment 1, except that: in the preparation of the positive electrode sheet, the distribution of the concave structure in the first region is adjusted so that S21 / S1×100%=50%, and other conditions remain unchanged to obtain the positive electrode sheet of this embodiment;

[0128] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example.

[0129] Examples 1-4

[0130] The preparation process of this embodiment is basically the same as that of embodiment 1, except that: in the preparation of the positive electrode sheet, the distribution of the concave structure in the first region is adjusted so that S21 / S1×100%=70%, and other conditions remain unchanged to obtain the positive electrode sheet of this embodiment;

[0131] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example.

[0132] Example 2

[0133] The preparation process of this embodiment is basically the same as that of embodiment 1, except that: in the preparation of the positive electrode sheet, the distribution range of the second region 12 is adjusted so that S2 / S1=1 / 49; S2=1980mm 2 (22*90mm), the area of ​​positive electrode collector 1 is 99000mm 2 (1100*90mm), S1=97020mm 2 , and the example of this embodiment is Figure 3 The positive electrode current collector of the structure shown in FIG. Figure 3 The positive electrode ear is welded at the position shown; other conditions remain unchanged to obtain the positive electrode sheet of this embodiment;

[0134] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example.

[0135] Example 3

[0136] The preparation process of this embodiment is basically the same as that of embodiment 1, except that: in the preparation of the positive electrode sheet, the distribution range of the second region 12 is adjusted so that S2 / S1=1 / 2; S2=33000mm 2 (1100*30mm), positive electrode current collector 1 area is 99000mm 2 (1100*90mm), S1=66000mm 2 , and the example of this embodiment is Figure 4 The positive electrode current collector is shown in FIG. Figure 4 The positive electrode ear is welded at the position shown; other conditions remain unchanged to obtain the positive electrode sheet of this embodiment;

[0137] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example.

[0138] Example 4

[0139] The preparation process of this embodiment is basically the same as that of embodiment 1, except that: in the preparation of the positive electrode sheet, the distribution range of the second region 12 is adjusted so that S2 / S1=1 / 2; S2=33000mm 2 (1100mm*15mm*2), positive electrode collector 1 area is 99000mm 2 (1100mm*90mm), S1=66000mm 2 , and the example of this embodiment is Figure 5 The positive electrode current collector is shown in FIG. Figure 5 The positive electrode ear is welded at the position shown; other conditions remain unchanged to obtain the positive electrode sheet of this embodiment;

[0140] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example.

[0141] Example 5

[0142] The preparation process of this embodiment is basically the same as that of embodiment 1, except that: in the preparation of the positive electrode sheet, the laser drilling power is adjusted, the formed hole is a blind hole (non-through hole), and the hole depth is 1 / 3 of the thickness of the positive electrode collector 1; the distribution range of the second region 12 is adjusted to make S2 / S1=1 / 149; S2=660mm 2 (122*30mm), positive electrode collector 1 area is 99000mm 2 (1100mm*90mm), S1=98340mm 2 ; Other conditions remain unchanged to obtain the positive electrode sheet of this embodiment;

[0143] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example.

[0144] Example 6

[0145] The preparation process of this embodiment is basically the same as that of embodiment 1, except that: in the preparation of the positive electrode sheet, the distribution range of the second region 12 is adjusted so that S2 / S1=1 / 19; S2=4950mm 2 (55*90mm), the positive electrode collector 1 area is 99000mm 2 (1100mm*90mm), S1=94050mm 2 , and the example of this embodiment is Figure 3 The positive electrode current collector of the structure shown in FIG. Figure 3 The positive electrode ear is welded at the position shown; other conditions remain unchanged to obtain the positive electrode sheet of this embodiment;

[0146] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example.

[0147] Example 7

[0148] The preparation process of this embodiment is basically the same as that of embodiment 1, except that: in the preparation of the positive electrode sheet, the distribution range of the second region 12 is adjusted so that S2 / S1=1 / 10; S2=9000mm 2 (100*90mm), positive electrode collector 1 area is 99000mm 2 (1100mm*90mm), S1=90000mm 2 , and the example of this embodiment is Figure 3 The positive electrode current collector of the structure shown in FIG. Figure 3 The positive electrode ear is welded at the position shown; other conditions remain unchanged to obtain the positive electrode sheet of this embodiment;

[0149] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example.

[0150] Example 8

[0151] The preparation process of this embodiment is basically the same as that of embodiment 1, except that: in the preparation of the positive electrode sheet, the distribution range of the second region 12 is adjusted so that S2 / S1=4 / 5; S2=44000mm 2 (1100*40mm), positive electrode collector 1 area is 99000mm 2 (1100mm*90mm), S1=55000mm 2 , and the example of this embodiment is Figure 4 The positive electrode current collector of the structure shown in FIG. Figure 4 The positive electrode ear is welded at the position shown; other conditions remain unchanged to obtain the positive electrode sheet of this embodiment;

[0152] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example.

[0153] Example 9

[0154] The preparation process of this embodiment is basically the same as that of embodiment 1, except that: in the preparation of the positive electrode sheet, the distribution range of the second region 12 is adjusted so that S2 / S1=1 / 4; S2=19800mm 2 (220*90mm), the area of ​​positive electrode collector 1 is 99000mm 2 (1100mm*90mm), S1=79200mm 2 , and the example of this embodiment is Figure 2 The positive electrode current collector of the structure shown in FIG. Figure 2 The positive electrode ear is welded at the position shown; other conditions remain unchanged to obtain the positive electrode sheet of this embodiment;

[0155] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example.

[0156] Example 10

[0157] The preparation process of this embodiment is basically the same as that of embodiment 1, except that: in the preparation of the positive electrode sheet, the laser drilling power is adjusted, the formed hole is a blind hole (non-through hole), and the hole depth is 1 / 10 of the thickness of the positive electrode collector 1; other conditions remain unchanged to obtain the positive electrode sheet of this embodiment;

[0158] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example.

[0159] Comparative Example 1

[0160] The preparation process of this embodiment is basically the same as that of embodiment 1, except that: step (1) is omitted, that is, conventional aluminum foil is used as the positive electrode current collector 1; other conditions remain unchanged, and the positive electrode sheet of this embodiment is obtained;

[0161] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example.

[0162] Comparative Example 2

[0163] The preparation process of this embodiment is basically the same as that of embodiment 1, except that: in step (1), the first functional surface of the aluminum foil is punched by laser, that is, the second area 12 is not reserved, S2=0; other conditions remain unchanged, and the positive electrode sheet of this embodiment is obtained;

[0164] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example.

[0165] Comparative Example 3

[0166] The preparation process of this embodiment is basically the same as that of embodiment 1, except that: in the preparation of the positive electrode sheet, the distribution range of the second region 12 is adjusted so that S2 / S1=2 / 1; S2=66000mm 2 (1100*60mm), positive electrode collector 1 area is 99000mm 2 (1100mm*90mm), S1=33000mm 2 , and the example of this embodiment is Figure 4 The positive electrode current collector of the structure shown in FIG. Figure 4 The positive electrode ear is welded at the position shown; other conditions remain unchanged to obtain the positive electrode sheet of this embodiment;

[0167] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example.

[0168] Comparative Example 4

[0169] The preparation process of this embodiment is basically the same as that of embodiment 1, except that: in the preparation of the positive electrode sheet, the distribution range of the second region 12 is adjusted; S2 = 100 mm 2 (10*10mm), the area of ​​positive electrode collector 1 is 99000mm 2 (1100mm*90mm), S1=98900mm 2 , and the example of this embodiment is Figure 4 The positive electrode current collector of the structure shown in FIG. Figure 4 The positive electrode ear is welded at the position shown; other conditions remain unchanged to obtain the positive electrode sheet of this embodiment;

[0170] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example.

[0171] Test example

[0172] 1. Screw extrusion test

[0173] Fully charge the lithium-ion battery and then place it on the test bench of the extrusion equipment. Place a screw with a screw diameter of 2mm and a screw length of 4mm in the middle of the battery, start the extrusion equipment, and squeeze the screw into the battery at a speed of 0.1mm / s. When the equipment pressure reaches 13KN, stop the test. If the battery does not catch fire or explode, the test is considered to have passed. The number of passes / the number of tests is the screw extrusion pass rate, and the number of tests is 30.

[0174] 2. Heavy object impact test:

[0175] Fully charge the lithium-ion battery and then place it on the test bench of the heavy object impact test equipment. Place a steel rod with a diameter of 15.8mm in the middle of the battery cell, start the equipment, and a heavy hammer weighing 9.1kg falls freely from a height of 610mm from the battery and hits the steel rod. The battery is considered to have passed the test if it does not catch fire or explode. The number of passes / number of tests is the pass rate of heavy object impact, and the number of tests is 30.

[0176] 3. Tab welding tensile test:

[0177] The aluminum tab (width 6-10mm) is laser welded to the welding area of ​​the positive current collector. After welding, the current collector with the tab is placed on the tensile gauge. The fixing clamp of the tensile gauge is used to clamp one end of the positive current collector first, and then the tensile gauge is moved to clamp the exposed end of the tab with the fixing clamp to ensure that it is horizontal and straight. Start the tensile gauge and record the peak tension when the sample is pulled off, which is recorded as the welding tension of the tab. The welding tension ≥15N is qualified, and less than 15N is unqualified.

[0178] 4. Energy density test:

[0179] Energy density = battery discharge energy / (battery length × height × width)

[0180] The specific parameters and test results of the positive electrode sheets in the above embodiments and comparative examples are shown in Table 1.

[0181] Table 1

[0182]

[0183]

[0184] By comparing Examples 1 to 8 with Comparative Example 1, it can be seen that the safety performance of the battery is significantly improved by using the positive electrode current collector having the first region compared to the conventional empty foil.

[0185] 2 2 When S1 < S2, the welding tensile force is qualified, ensuring that the battery has good stability.

[0186] Comparing Example 1, Comparative Example 2 and Comparative Example 4, it can be seen that when the positive tab is welded to the second region of the positive current collector and satisfies 100 mm

[0187] Comparing Example 1, Examples 1-1 to 1-4, it can be seen that by limiting S21 / S2×100% = 5% to 50%, while ensuring that the welding tensile force of the positive tab is qualified and improving the safety performance of the battery, it can also ensure that the battery has a high energy density.

[0188] It should be noted here that the numerical values and numerical ranges involved in the embodiments of the present invention are approximate values. Affected by the manufacturing process, there may be a certain range of errors, and those skilled in the art can consider this part of the errors to be negligible.

[0189] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

[0190] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An electrode sheet, characterized in that: Including current collector, safety base coating, active layer and tab; The current collector includes a first region and a second region; the first region is provided with X concave structures, X≥1, The safety primer layer is disposed in at least part of the functional surface of the first region and at least part of the concave structure, and the active layer is disposed on the surface of the safety primer layer away from the current collector; The area of ​​the second region is S2, the area of ​​the first region is S1, and the 100mm 2 <S2<S1; The electrode tab is disposed on the functional surface of the second region and is electrically connected to the current collector.

2. The electrode sheet according to claim 1, characterized in that: The electrode sheet is a positive electrode sheet.

3. The electrode sheet according to claim 1, characterized in that: The S1 and S2 satisfy, and S1 / S2 is 1-150.

4. The electrode sheet according to claim 1, characterized in that: Active layers are arranged on at least two sides of the electrode tab.

5. The electrode sheet according to claim 1, characterized in that: The second region is adjacent to the first region at both ends in the length direction of the current collector; in the width direction of the current collector, the size of the first region is W1, the size of the second region is W2, and 0.2≤W2 / W1≤1.

6. The electrode sheet according to claim 1, characterized in that: The first region and the second region are alternately distributed in a width direction of the current collector, and the second region is located on at least one side of the current collector in the width direction.

7. The electrode sheet according to claim 1, characterized in that: The electrode sheet includes M second regions and N electrode tabs, 1≤N, 1≤M.

8. The electrode sheet according to claim 7, characterized in that: The orthographic projection area of ​​each of the pole tabs in the second region is at least 30% of the area of ​​the pole tab; or, the ratio of the orthographic projection area of ​​each of the pole tabs in the second region to the area of ​​the second region is 1-95%.

9. The electrode sheet according to claim 1, characterized in that: The orthographic projection area of ​​the concave structure in the first region on the first plane is S21, S21 / S2×100%=5%-50%, and the first plane is parallel to the functional surface of the current collector; and / or, The depth of the recessed structure is d1, the thickness of the current collector is d2, wherein 1 / 3≤d1 / d2≤1; and / or the size of the opening end of the recessed structure is L1, and the center line spacing between adjacent recesses is L2, wherein 1≤L2 / L1≤10.

10. The electrode sheet according to claim 9, characterized in that: L1 is 10 to 300 μm; and / or L2 is 10 to 10000 μm, and / or d1 is 1 to 10 μm, and / or d2 is 3 to 15 μm.

11. A battery cell, characterized in that: The electrode sheet comprises any one of claims 1 to 10.

12. The battery cell according to claim 11, characterized in that: The battery cell is a wound battery cell, and the opening end of the recessed structure in the first region of the electrode sheet faces a side away from the center of the battery cell.

13. A battery, characterized in that: Comprising the battery cell as claimed in claim 11.

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