Pole piece and battery

Abstract

The utility model provides a pole piece and a battery. The pole piece comprises a current collector, a safe priming coat and an active layer which are laminated, the current collector is provided with N sunken structures, openings of the sunken structures are located on the functional surface of the current collector, and N is greater than or equal to 1; and at least part of the safety bottom coating is embedded into the concave structure of the current collector. The pole piece provided by the utility model can solve the problem that the fracture surface of the current collector is easy to expose in the prior art, 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 in particular relates to a pole piece and a battery. Background Art

[0002] Lithium-ion batteries have been widely used in many fields such as electronic products, power vehicles, and energy storage due to their small size, high energy density, high platform voltage, and no memory effect, providing great convenience for modern life and production. At the same time, there are also great safety risks in batteries, especially when they are subjected to mechanical abuse (puncture, extrusion, etc.), the short-circuit contact between the positive current collector and the negative active material layer is the most likely factor to cause fire and explosion. In order to improve the safety performance of lithium-ion batteries, most of them are currently provided with a safety primer between the positive current collector and the positive active layer to prevent the positive current collector from directly contacting the negative active material layer. However, when the battery is subjected to external force, the components in the battery core are depressed or even broken inwardly, and the fracture surface of the current collector will be exposed, and the fracture surface will contact the adjacent negative active material layer, which is not conducive to the improvement of safety performance. Therefore, how to further improve the safety performance of batteries is a technical problem to be solved in this field. Utility Model Content

[0003] The utility model provides a pole piece to solve the problem in the prior art that the fracture surface of the current collector of the pole piece is easily exposed, thereby further improving the safety performance of the battery.

[0004] The utility model provides an electric core and a battery. As the electric core and the battery include the pole piece, the battery composed of the pole piece has excellent safety performance.

[0005] The utility model provides a pole piece, comprising a stacked current collector, a safety primer layer, and an active layer; the current collector is provided with N recessed structures, the openings of the recessed structures are located on the functional surface of the current collector, and N≥1; at least part of the safety primer layer is embedded in the recessed structure of the current collector.

[0006] The pole piece as described above, wherein the current collector comprises first regions and second regions that are alternately arranged;

[0007] In the first region, the distribution density of the recessed structures is n, where n>0;

[0008] In the second region, the distribution density of the recessed structures is m, where m=0 or m>n.

[0009] The pole piece as described above, m=0, the first region and the second region are alternately distributed along the length direction of the current collector, the size of the second region in the length direction of the current collector is D2, and the distance between the opening centers of adjacent recessed structures in the first region in the length direction of the current collector is L2, wherein D2≥L2;

[0010] or,

[0011] m=0, the first region and the second region are alternately distributed along the width direction of the current collector, the size of the second region in the width direction of the current collector is D2, and the distance between the opening centers of adjacent recessed structures in the first region in the length direction of the current collector is L2, wherein D2≥L2.

[0012] The pole piece as described above, m>n, the first region and the second region are alternately distributed along the length direction of the current collector, the size of the second region in the length direction of the current collector is D1, and the distance between the opening centers of adjacent recessed structures in the first region in the length direction of the current collector is L1, wherein D1≥L1×2;

[0013] or,

[0014] m>n, the first region and the second region are alternately distributed along the width direction of the current collector, the size of the second region in the width direction of the current collector is D1, and the distance between the opening centers of adjacent recessed structures in the first region in the width direction of the current collector is L1, wherein D1≥L1×2.

[0015] For the pole piece as described above, the size of the first region in the length direction of the current collector is A1, the size of the current collector in the length direction is A, and A1 ≥ 10% A;

[0016] The size of the first region in the width direction of the current collector is B1, the size of the current collector in the width direction is B, and B1≥10%B.

[0017] The pole piece as described above, the size of the opening of the recessed structure is L3, and the distance between the centers of the openings of adjacent recessed structures is L4, wherein 1<L4 / L3≤10;

[0018] And / or, the thickness of the current collector is d1, the depth of the recessed structure is d2, and the following conditions are satisfied: 0.2≤d2 / d1≤1;

[0019] And / or, the distance between the opening centers of adjacent recessed structures is L4, and the distance between the recessed structure and the edge of the current collector in the width direction is C1, satisfying: C1≥0.5×L4;

[0020] And / or, the size of the opening of the recessed structure is L3, the distance between the recessed structure and the edge of the current collector is C1, and L3 / C1≥0 is satisfied;

[0021] And / or, the edge of the opening of the recessed structure has a convex structure, the convex structure has a width w and a height h1, wherein 1 μm≤w≤L3×2, 0.1 μm≤h1≤L3×2.

[0022] For the pole piece as described above, L3 is 10-300 μm; L4 is 10-10000 μm, d2 is 1-20 μm, d1 is 4-20 μm, C1 is 5-5000 μm, w is 1-600 μm, and h1 is 0.1-600 μm.

[0023] The pole piece as described above further comprises a pole ear, wherein the pole ear is electrically connected to the current collector;

[0024] The distance between the edge of the opening of the recessed structure and the edge of the tab is F, where F≥1 mm.

[0025] The pole piece as described above further comprises a protective layer;

[0026] Along the length direction of the current collector, the protective layer is adjacent to the safety primer layer and covers at least a portion of the functional surface of the current collector, and the protective layer is at least partially embedded in the recessed structure;

[0027] Alternatively, along the length direction of the current collector, the protective layer is adjacent to the active layer and covers at least a portion of the surface of the safety primer layer away from the current collector;

[0028] The material of the protective layer includes at least one of a first material or a modified product of the first material, wherein the first material includes at least one of 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, lithium nickel cobalt aluminum oxide, lithium titanate, aluminum oxide, boehmite, titanium dioxide, zirconium oxide, silicon dioxide and a conductive polymer.

[0029] The pole piece as described above, the material of the safety undercoat layer includes at least one of the first material or the modified product of the first material, wherein the first material includes at least one of 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 rich manganese-based material, lithium nickel cobalt aluminum oxide, lithium titanate, aluminum oxide, boehmite, titanium dioxide, zirconium oxide, silicon dioxide and conductive polymer;

[0030] The material of the active layer includes at least one of 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 rich manganese-based material, and lithium nickel cobalt aluminum oxide.

[0031] The pole piece as described above is a positive pole piece.

[0032] In another aspect, the utility model provides a battery, comprising the pole piece as described above.

[0033] The battery as described above comprises an electrode assembly and a housing, wherein the electrode assembly comprises the electrode sheet, the separator, and the second electrode sheet as described above, which are stacked and wound.

[0034] The pole piece also includes a protective layer;

[0035] Along the length direction of the current collector, the protective layer is adjacent to the safety primer layer and covers at least a portion of the functional surface of the current collector, and the protective layer is at least partially embedded in the recessed structure;

[0036] Alternatively, along the length direction of the current collector, the protective layer is adjacent to the active layer and covers at least a portion of the surface of the safety primer layer away from the current collector;

[0037] Along the winding direction, the protective layer is located at the tail of the winding core of the electrode assembly.

[0038] In the battery as described above, the opening end of the recessed structure of the pole piece faces a side away from the center of the battery cell.

[0039] The implementation of the utility model has at least the following beneficial effects:

[0040] The pole piece provided by the utility model has a recessed structure on the surface of the current collector, a recessed coating on the inner surface of at least part of the recessed structure, and a surface coating on at least part of the functional surface, wherein the recessed coating and the surface coating sequentially include a safety bottom coating and an active layer in a direction away from the current collector. When the pole piece is applied to a battery, when the battery is damaged by external force and causes the battery to deform or break inward, the recessed structure of the current collector will deform and break before other parts of the current collector. At this time, the safety bottom coating in the recessed coating covering the recessed structure can slide and spread inward in the direction of damage, so that the fracture surface of the current collector is covered and protected by the coating material, thereby avoiding exposure of the current collector and increasing the resistance when the positive and negative electrodes are in short circuit contact, effectively reducing the short circuit current, thereby improving the safety performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0042] Figure 1 This is a schematic diagram of the cross-sectional structure of a pole piece in one embodiment of the utility model;

[0043] Figure 2 is a schematic diagram of the cross-sectional structure of a pole piece in another embodiment of the utility model;

[0044] Figure 3 It is a schematic diagram of a top view of a connection structure between a current collector and a pole ear in a pole piece in one embodiment of the utility model;

[0045] Figure 4 It is a schematic diagram of a top view of a connection structure between a current collector and a pole ear in a pole piece in another embodiment of the utility model;

[0046] Figure 5 It is a schematic diagram of a top view of a connection structure between a current collector and a pole ear in a pole piece in another embodiment of the utility model;

[0047] Figure 6 It is a schematic diagram of a top view of a connection structure between a current collector and a pole ear in a pole piece in yet another embodiment of the present invention;

[0048] Figure 7 It is a schematic diagram of a top view of a connection structure between a current collector and a pole ear in a pole piece in one embodiment of the utility model;

[0049] Figure 8 It is a schematic diagram of a top view of a connection structure between a current collector and a pole ear in a pole piece in one embodiment of the utility model;

[0050] Fig. 9 It is a schematic diagram of a partial cross-sectional structure of a pole piece in one embodiment of the utility model;

[0051] Fig.10 This is a SEM image of a cross section of a pole piece in one embodiment of the utility model;

[0052] Fig.11 This is a top view SEM image of the current collector in the pole piece in one embodiment of the utility model;

[0053] Fig.12 It is a schematic diagram of the top view structure of the current collector in the pole piece in another embodiment of the utility model.

[0054] Description of reference numerals:

[0055] 1-current collector; 11-first functional surface; 12-second functional surface; 101-first region; 102-second region;

[0056] 2-coating; 201-safety base coating; 202-active layer; 203-protective layer; 3-recessed structure; 4-convex structure; 5-ear. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0058] In the description of the present utility model, terms such as "first" and "second" are only used for descriptive purposes, such as distinguishing various components to more clearly illustrate / explain the technical solution.

[0059] Figures 1 to 11 , 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 .

[0060] On the one hand, the utility model provides a pole piece, including a stacked current collector 1, a safety bottom coating 201, and an active layer 202; the current collector 1 is provided with N recessed structures 3, the openings of the recessed structures 3 are located on the functional surface of the current collector 1, N ≥ 1; at least part of the safety bottom coating 201 is embedded in the recessed structure 3 of the current collector 1.

[0061] The electrical property of the pole piece of the utility model can be a negative pole piece or a positive pole piece.

[0062] The functional surface of the current collector refers to the outermost surface in the length direction and width direction of the current collector, that is, the two largest and opposite surfaces among the six surfaces of the current collector, such as Figure 1 and Figure 2 The first functional surface 11 and the second functional surface 12 in the embodiment.

[0063] The recessed structure 3 of the utility model is a structure with a cavity formed by the first functional surface 11 being recessed toward the second functional surface 12, or a structure with a cavity formed by the second functional surface 12 being recessed toward the first functional surface 11. Specifically, conventional methods in the art can be used to provide the current collector 1 with the recessed structure 3 with a cavity. For example, mechanical punching, laser pore making, electric or thermal light melting, radiation melting, chemical corrosion, friction punching and other processing methods can be used.

[0064] The recessed structure 3 may or may not penetrate the current collector 1 in the thickness direction of the current collector 1. When the recessed structure 3 penetrates the current collector 1 in the thickness direction of the current collector 1, as shown in FIG. Figure 1 and Figure 2As shown, the recessed structure 3 has two oppositely disposed ends, which intersect the first functional surface 11 and the second functional surface 12 respectively. At this time, the notch formed on the first functional surface 11 and the second functional surface 12 is the opening of the recessed structure 3; when the recessed structure 3 does not penetrate the current collector 1 in the thickness direction of the current collector 1, as shown in FIG. Fig. 9 As shown, the opening of the recessed structure 3 is a notch on the first functional surface 11 .

[0065] The number of the recessed structures 3 may be one or more. When the number of the recessed structures 3 is multiple, the multiple recessed structures 3 are distributed in the extension direction of the current collector 1, and any two recessed structures are independent of each other without overlapping or covering each other. Fig.12 shown.

[0066] It should be noted that the present invention does not specifically limit the three-dimensional shape of the recessed structure 3. When there are multiple recessed structures 3, the multiple recessed structures 3 are independently arranged, and their cross-sectional shapes in the planes where the thickness and width are located, as well as whether they penetrate the current collector 1, are independent. For example, the cross-sectional shapes of some recessed structures 3 are triangular, and the cross-sectional shapes of some recessed structures 3 are rectangular; some recessed structures 3 penetrate the current collector 1 (in this case, the recessed structures 3 can be understood as through holes), and some recessed structures 3 do not penetrate the current collector 1 (in this case, the recessed structures 3 can be understood as blind holes).

[0067] At least a portion of the safety primer layer 201 is embedded in the recessed structure 3 of the current collector 1 . It can be understood that the safety primer layer 201 can cover at least a portion of the functional surface of the current collector 1 .

[0068] The utility model does not limit the specific composition of the safety primer coating 201. In one embodiment, the material of the safety primer coating 201 includes at least one of 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 oxyvanadium phosphate, lithium-rich manganese-based materials, lithium nickel cobalt aluminum oxide, lithium titanate, aluminum oxide, boehmite, titanium dioxide, zirconium oxide, zinc oxide, silicon dioxide, silicon carbide, silicon nitride, conductive polymers and their modifications.

[0069] The utility model also does not limit the specific composition of the active layer. For example, when the electrode is a positive electrode, the active layer includes at least one of 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 rich manganese-based material, and lithium nickel cobalt aluminum oxide.

[0070] Furthermore, the active layer 202 and the safety bottom coating 201 each independently contain a conductive agent, wherein the conductive agent 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 that the possibility of short circuit is reduced, a good conductive network is given to the active layer 202 and the safety bottom coating 201, which can ensure smooth electronic conduction between the active layer 202, the safety bottom coating 201 and the current collector 1, so that the battery has excellent safety performance and good cycle performance.

[0071] The active layer 202 and the safety bottom coating 201 each independently contain a binder, and the binder includes at least one of polyvinylidene fluoride, polyvinylidene chloride, polytetrafluoroethylene, polyhexafluoropropylene, polyacrylic acid, polyacrylate, polyamide, polyacrylonitrile, carboxymethyl cellulose sodium, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, styrene-butadiene rubber, polyethylene oxide, styrene-butadiene emulsion, styrene-acrylic emulsion, polyethyl acrylate, polybutyl methacrylate, ethylene-vinyl acetate copolymer, polyvinyl acetate or at least one of its modified products and copolymers, for example, the copolymer of polyvinylidene fluoride includes polyvinylidene fluoride-trifluoroethylene, polyvinylidene fluoride-tetrafluoroethylene, polyvinylidene fluoride-hexafluoroethylene, and polyvinylidene fluoride-hexafluoropropylene. In this way, the active layer 202 and the safety bottom coating 201 are fixedly bonded to the current collector 1.

[0072] The present invention does not limit the preparation process of the stacked safety primer layer 201 and the active layer 202 .

[0073] In a specific embodiment, the preparation method includes: preparing a safety primer layer 201 slurry and uniformly coating it on the first functional surface 11 of the current collector 1, obtaining the first safety primer layer 201 after drying, preparing an active layer 202 slurry and coating it on the first safety primer layer 201, and after drying, using a punching device to process the second functional surface 12 of the current collector 1 to obtain the current collector 1 including the recessed structure 3, preparing a safety primer layer 201 slurry and uniformly coating it on the inner surface of the recessed structure 3 of the current collector 1 and the second functional surface 12 of the current collector 1, obtaining the second safety primer layer 201 after drying, preparing an active layer 202 slurry and coating it on the second safety primer layer 201, and obtaining the pole piece after drying.

[0074] The utility model can avoid safety problems caused by battery short circuit by setting a recessed structure 3 on the current collector 1 and embedding at least part of the safety bottom coating in the recessed structure 3 of the current collector 1. 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 3 is located on the functional surface of the current collector 1, so that the fracture of the current collector 1 is more likely to occur at the recessed structure 3. At this time, the safety bottom coating 201 covering the recessed structure 3 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 safety bottom coating 201, 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.

[0075] Furthermore, in a specific embodiment of the present invention, the current collector 1 includes a first region 101 and a second region 102 that are alternately arranged; in the first region 101, the distribution density of the recessed structure 3 is n, n>0; in the second region 102, the distribution density of the recessed structure 3 is m, m=0 or m>n.

[0076] The distribution density of the recessed structures 3 refers to the number of the recessed structures 3 per unit area on the functional surface of the current collector 1 .

[0077] The first regions 101 and the second regions 102 alternately arranged in the current collector 1 may refer to the first regions 101 and the second regions 102 alternately arranged in the length direction of the current collector 1 , or may refer to the first regions 101 and the second regions 102 alternately arranged in the width direction of the current collector 1 .

[0078] like Figure 4 As shown, in a specific embodiment, the current collector 1 includes a first region 101, a second region 102 (m>n), a first region 101, and a second region 102 (m=0) arranged in sequence along the length direction.

[0079] like Figure 5 As shown, in a specific embodiment, the current collector 1 includes a first region 101, a second region 102 (m=0), a first region 101, and a second region 102 (m=0) arranged in sequence along the length direction.

[0080] like Figure 6 As shown, in a specific embodiment, the current collector 1 includes a first region 101 and a second region 102 (m=0) arranged sequentially along the width direction.

[0081] like Figure 7 As shown, in a specific embodiment, the current collector 1 includes a first region 101, a second region 102 (m>n), a first region 101, and a second region 102 (m=0) arranged in sequence along the width direction.

[0082] It is understood that when the current collector 1 includes alternately arranged first regions 101 and second regions 102, the distribution density n of the first regions 101 at different positions may be the same or different. Similarly, the distribution density m of the second regions 102 at different positions may be the same or different.

[0083] Further, in a specific embodiment of the present invention, Figure 5 As shown, m=0, the first region 101 and the second region 102 are alternately distributed along the length direction of the current collector 1, the size of the second region 102 in the length direction of the current collector 1 is D2, and the distance between the opening centers of adjacent recessed structures 3 in the first region in the length direction of the current collector 1 is L2, wherein D2≥L2; or Figure 8 As shown, m=0, the first region 101 and the second region 102 are alternately distributed along the width direction of the current collector 1, the size of the second region 102 in the width direction of the current collector 1 is D2, and the distance between the opening centers of adjacent recessed structures 3 in the first region in the length direction of the current collector 1 is L2, wherein D2≥L2.

[0084] When m=0, the second region is a region without a recessed structure.

[0085] When the first region 101 and the second region 102 are alternately distributed along the length direction of the current collector 1 and include a plurality of second regions 102 , the size of each second region 102 in the length direction satisfies the above relationship D2 ≥ L2 .

[0086] When the first region 101 and the second region 102 are alternately distributed along the width direction of the current collector 1 and include a plurality of second regions 102 , the size of each second region 102 in the width direction satisfies the above relationship D2 ≥ L2 .

[0087] When the first region 101 and the second region 102 in the current collector 1 are arranged according to the above rules, not only can the pole piece be broken at the position of the recessed structure when damaged by external force, so that the safety primer layer slides to the fracture surface to prevent short circuit, but also the mechanical properties of the pole piece itself can be guaranteed and the safety performance can be improved.

[0088] Further, in a specific embodiment of the present invention, Figure 4 As shown, m>n, the first region 101 and the second region 102 are alternately distributed along the length direction of the current collector 1, the size of the second region 102 in the length direction of the current collector 1 is D1, and the distance between the opening centers of adjacent recessed structures 3 in the first region in the length direction of the current collector 1 is L1, wherein D1≥L1×2; or Figure 7As shown, m>n, the first region 101 and the second region 102 are alternately distributed along the width direction of the current collector 1, the size of the second region 102 in the width direction of the current collector 1 is D1, and the distance between the opening centers of adjacent recessed structures 3 in the first region in the width direction of the current collector 1 is L1, wherein D1≥L1×2.

[0089] When the first region 101 and the second region 102 in the current collector 1 are arranged according to the above rules, the safety performance of the pole piece can be further improved to ensure that the pole piece is broken at the position of the recessed structure when damaged by external force.

[0090] Further, in a specific embodiment of the present invention, Figure 4-Figure 5 As shown, the size of the first region 101 in the length direction of the current collector 1 is A1, the size of the current collector 1 in the length direction is A, and A1 ≥ 10% A; Figure 6-Figure 8 As shown, the size of the first region 101 in the width direction of the current collector 1 is B1, the size of the current collector 1 in the width direction is B, and B1≥10%B.

[0091] Specifically, the dimension A1 of the first region 101 in the length direction of the current collector 1 refers to the center distance between the two holes in the first region that are on the same straight line along the length direction of the current collector 1. The dimension A of the current collector 1 in the length direction refers to the length of the current collector 1 in the extension direction.

[0092] The dimension B1 of the first region 101 in the width direction of the current collector 1 refers to the center distance between the two holes in the first region that are on the same straight line along the width direction of the current collector. The dimension B of the current collector 1 in the width direction refers to the width of the functional plane of the current collector 1.

[0093] When the dimensions of the first region and the current collector in the width or length direction are within the above range, it can avoid the situation where, when the pole piece is damaged by external force, the fracture does not occur at the recessed structure due to insufficient proportion of the first region, thereby causing a short circuit on the fracture surface.

[0094] Further, in a specific embodiment of the present invention, the size of the opening of the recessed structure 3 is L3, and the distance between the centers of the openings of adjacent recessed structures 3 is L4, wherein 1≤L4 / L3≤10; and / or, the thickness of the current collector 1 is d1, and the depth of the recessed structure 3 is d2, satisfying: 0.2≤d2 / d1≤1; and / or, the distance between the centers of the openings of adjacent recessed structures 3 is L4, and the distance between the recessed structure 3 and the edge of the current collector 1 is C1, satisfying: C1≥0.5×L4; and / or, the size of the opening of the recessed structure 3 is L3, and the distance between the recessed structure 3 and the edge of the current collector 1 is C1, satisfying L3 / C1≥0. and / or, the edge of the opening of the recessed structure 3 has a convex structure, and the width of the convex structure is w, and the height is h1, wherein 1μm≤w≤L3×2, 0.1μm≤h1≤L3×2.

[0095] The maximum size L3 of the opening of the recessed structure 3 refers to the distance between the two points on the edge of the opening that are farthest apart. For example, when the opening is circular, the maximum size L3 of the opening of the recessed structure 3 is the length of the diameter of the circle; when the opening is rectangular, the maximum size L3 of the opening of the recessed structure is the length of the diagonal of the rectangle.

[0096] It can be understood that when the same current collector 1 has recessed structures 3 with different three-dimensional shapes, the maximum size L3 of the opening of the recessed structure 3 is the maximum value of the opening sizes of all the recessed structures 3 .

[0097] Likewise, the maximum distance L4 between the opening centers of adjacent recessed structures 3 is the maximum value among the distances between the opening centers of all adjacent recessed structures 3 .

[0098] By defining the relationship between L3 and L4, the pore density can be achieved within the above range, thereby improving both the mechanical strength of the current collector 1 and the safety performance of the battery.

[0099] like Fig. 9 As shown, the thickness d1 of the current collector 1 refers to the straight-line distance between the first functional surface 11 and the second functional surface 12 of the current collector 1 which are arranged opposite to each other.

[0100] The depth of the recessed structure 3 refers to the distance between the lowest end of the cavity in the recessed structure 3 and the open end of the recessed structure 3 along the thickness direction.

[0101] When d2 / d1=1, the depth d2 of the recessed structure 3 is consistent with the thickness d1 of the current collector 1, that is, the recessed structure 3 penetrates the current collector 1; when 0.2≤d2 / d1<1, the recessed structure 3 does not penetrate the current collector 1 in the thickness direction of the current collector 1. By limiting 0.2≤d2 / d1≤1, on the one hand, it is ensured that when the battery containing the above-mentioned pole piece is damaged by external force, the current collector 1 is more likely to break along the position of the recessed structure 3, reducing the probability of the current collector cross section in the current collector 1 being exposed, and when the current collector 1 breaks, the safety primer layer can slide along the fracture to the fracture surface of the current collector 1 to provide protection for the fracture surface.

[0102] like Figure 3-Figure 8 As shown, the distance between the centers of the openings of adjacent recessed structures 3 and the distance between the edge of the current collector 1 is C1, C1 ≥ 0.5 × L4. The edge of the current collector 1 may refer to the edge of the current collector 1 in the length direction or the width direction, so that the continuity of the edge of the current collector 1 is ensured, and burrs on the edge of the current collector 1 are avoided to prevent short circuits, thereby further improving the safety performance of the battery.

[0103] like Fig. 9 As shown, the edge of the opening of the recessed structure 3 has a protruding structure 4 , and the protruding structure 4 has a width w and a height h1 , wherein 1 μm≤w≤L3×2, and 0.1 μm≤h1≤L3×2.

[0104] The edge of the opening of the recessed structure 3 can be understood as the surface around the opening end. The raised structure 4 refers to: in the extension direction of the current collector 1, the ring shape formed by the opening end of the recessed structure 3 extends along one side away from the center direction of the opening of the recessed structure 3, and at the same time, in the thickness direction of the current collector 1, the surface where the opening end of the recessed structure 3 is located is used as a reference, and the raised structure is formed in the direction away from the functional surface of the current collector 1. By limiting w, h1 and d to satisfy the above relationship, the size of the raised structure 4 is prevented from being too wide or too thick to affect the loading amount and adhesion of the safety bottom coating, so that the coating area of ​​the safety bottom coating is within a reasonable range, thereby ensuring the stability of the positive electrode sheet and the energy density of the battery.

[0105] In one embodiment, the opening shape of the concave structure 3 is circular, and the convex structure 4 is an annular structure formed with the circular edge of the opening edge of the concave structure 3 as the edge and away from the center of the concave structure 3 .

[0106] The width w of the raised structure 4 is the distance extending toward the side away from the opening end of the recessed structure 3 based on the opening edge of the recessed structure 3; the height h1 of the raised structure 4 refers to the height of the raised structure 4 in the thickness direction of the current collector 1, based on the surface where the opening end of the recessed structure 3 is located, and toward the direction away from the current collector 1.

[0107] Further, in a specific embodiment of the present invention, L3 is 10-300 μm; L4 is 10-10000 μm, d2 is 1-20 μm, d1 is 4-20 μm, C1 is 5-5000 μm, w is 1-600 μm, and h1 is 0.1-600 μm.

[0108] Specifically, L1 is 5 to 300 μm, for example, 5 μm, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm or a range consisting of any two thereof.

[0109] L2 is 10 to 10000 μm, for example, 10 μm, 20 μm, 30 μm, 50 μm, 100 μm, 200 μm, 300 μm, 500 μm, 1000 μm, 2000 μm, 3000 μm, 4000 μm, 5000 μm, 6000 μm, 7000 μm, 8000 μm, 9000 μm, 10000 μm, or a range consisting of any two of them.

[0110] d2 is 1 to 20 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm or a range consisting of any two thereof.

[0111] d1 is 4 to 12 μm, for example, 4 μm, 5 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 or a range consisting of any two thereof.

[0112] C1 is 5-5000 μm, for example, 5 μm, 10 μm, 50 μm, 100 μm, 500 μm, 1000 μm, 2000 μm, 3000 μm, 4000 μm, 5000 μm or a range between any two of them.

[0113] w is 1-600 μm, for example, 1 μm, 10 μm, 50 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm or a range between any two thereof.

[0114] h1 is 0.1-600 μm, for example, 0.1 μm, 10 μm, 50 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm or a range between any two of them.

[0115] When the above parameters are met, the distribution and morphology of the recessed structure on the current collector can be ensured to be within an appropriate range. If it is not within the above range, there will be insufficient protection of the fracture surface when the current collector breaks, and the safety improvement effect will be poor, or it may cause the current collector strength to drop significantly and break, and the impedance will increase significantly.

[0116] Further, in a specific embodiment of the present invention, Figure 3-Figure 8 As shown, the pole piece further includes a pole ear 5, which is electrically connected to the current collector; the distance between the edge of the opening of the recessed structure 3 and the edge of the pole ear 5 is F, where F≥1 mm.

[0117] The pole lug 5 is electrically connected to the current collector point, and can be a conventional structure or a pole lug-center structure, wherein the conventional structure means that the pole lug 5 is located at one end of the pole piece, and the pole lug-center structure means that the pole lug 5 is located in the middle of the pole piece.

[0118] The distance F between the edge of the opening of the recessed structure 3 and the edge of the pole lug 5 refers to the minimum distance between the edge position of the connection end of the pole lug 5 and the current collector 1 and the opening edge of the recessed structure 3 that is closest to it.

[0119] When the positional relationship between the pole tab 5 and the recessed structure 3 meets the above conditions, the welding strength of the pole tab can be further guaranteed, the stability of the pole tab can be improved, the pole sheet resistance can be further reduced, and uneven welding or cold welding can be avoided.

[0120] Furthermore, in a specific embodiment of the present invention, a protective layer 203 is also included; Figure 1 As shown, along the length direction of the current collector 1, the protective layer 203 is adjacent to the safety primer layer 201 and covers at least part of the functional surface of the current collector 1, and the protective layer 203 is at least partially embedded in the recessed structure 3; or, as shown in Figure 2 As shown, along the length direction of the current collector 1, the protective layer 203 is adjacent to the active layer 202 and covers at least part of the surface of the safety primer layer 201 away from the current collector; the material of the protective layer includes at least one of the first material or the first material modification, wherein the first material includes at least one of 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 rich manganese-based material, lithium nickel cobalt aluminum oxide, lithium titanate, aluminum oxide, boehmite, titanium dioxide, zirconium oxide, silicon dioxide and a conductive polymer.

[0121] The protective layer 203 can prevent the current collector from being exposed and causing a short circuit, thereby further improving the safety performance of the electrode.

[0122] Further, in a specific embodiment of the present invention, the material of the safety primer layer includes at least one of the first material or the first material modification, wherein the first material includes at least one of 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, silicon dioxide and a conductive polymer; the material of the active layer includes at least one of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium cobalt manganese oxide, lithium iron phosphate, lithium vanadium phosphate, lithium manganese-rich material, lithium nickel cobalt aluminum oxide, lithium titanate, aluminum oxide, boehmite, titanium dioxide, zirconium oxide, silicon dioxide and a conductive polymer; At least one of lithium manganese oxide, lithium iron phosphate, lithium iron manganese phosphate, lithium vanadium phosphate, lithium vanadium phosphate, lithium rich manganese-based materials, and lithium nickel cobalt aluminum oxide; the material of the protective layer includes at least one of the first material or the first material modification, wherein the first material includes at least one of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium iron manganese phosphate, lithium vanadium phosphate, lithium vanadium phosphate, lithium rich manganese-based materials, lithium nickel cobalt aluminum oxide, lithium titanate, aluminum oxide, boehmite, titanium dioxide, zirconium oxide, silicon dioxide and a conductive polymer.

[0123] The use of the above materials can not only provide good protection, but also will not lose the energy density of the electrode, so that the electrode can maintain relatively excellent electrochemical properties.

[0124] Furthermore, in a specific embodiment of the present invention, the electrode sheet is a positive electrode sheet.

[0125] In another aspect, the utility model provides a battery, comprising the pole piece as described above.

[0126] The battery of the present invention is preferably a lithium-ion battery, including but not limited to a soft-pack battery, a square battery, a cylindrical battery, etc.

[0127] 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.

[0128] 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.

[0129] Furthermore, in a specific embodiment of the present invention, the battery includes an electrode assembly and a shell, the electrode assembly includes the electrode sheet, the diaphragm, and the second electrode sheet as described above, which are stacked and wound, and the electrode sheet also includes a protective layer; along the length direction of the current collector, the protective layer is adjacent to the safety primer layer and covers at least part of the functional surface of the current collector, and the protective layer is at least partially embedded in the recessed structure; or, along the length direction of the current collector, the protective layer is adjacent to the active layer and covers at least part of the surface of the safety primer layer away from the current collector; along the winding direction, the protective layer is located at the tail of the winding core of the electrode assembly.

[0130] The second pole piece has a polarity opposite to that of the pole piece provided by the utility model.

[0131] Furthermore, the electrode sheet is a positive electrode sheet, and the second electrode sheet is a negative electrode sheet.

[0132] In detail, the positive electrode sheet, the separator, and the negative electrode sheet are stacked in sequence to obtain a laminate, and the laminate is wound along the winding direction to obtain the winding core provided by the utility model. During the winding process, one end of the laminate is used as the starting end until the winding operation is completed. At this time, the starting end is located inside the winding core, and the other end is outside the winding core, that is, the ending end, and the protective layer is located at the ending end of the winding core.

[0133] Since the winding core of the utility model includes the pole piece as described above, the winding core has excellent safety performance.

[0134] Furthermore, in a specific embodiment of the present invention, the opening end of the recessed structure 3 of the pole piece faces a side away from the center of the battery cell.

[0135] The opening end of the recessed structure 3 faces the side away from the center of the battery cell, that is, the opening end of the recessed structure 3 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 safety primer coating covering the inner surface of the recessed structure 3 can slide and spread inward in the direction of damage, effectively protecting the fracture surface of the current collector 1 from exposure, thereby avoiding the short circuit problem caused by the exposure of the fracture surface of the current collector 1.

[0136] The present invention will be further described below through specific embodiments.

[0137] Example 1

[0138] (1) Preparation of safety primer coating slurry: lithium iron phosphate (LFP), aluminum oxide (Al2O3), conductive carbon black (SP), polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) in a mass ratio of 86:10:1:3 are mixed, and the mixture is stirred and evenly mixed to obtain a safety primer coating slurry;

[0139] Preparation of the second safety primer coating slurry: Alumina (Al2O3), polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) are mixed in a mass ratio of 90:10, and stirred and mixed to obtain the second safety primer coating slurry;

[0140] Preparation of positive electrode active layer slurry: lithium cobalt oxide (LCO), conductive carbon black (SP), polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) in a mass ratio of 97.5:1:1.5 are mixed, and stirred to mix evenly to obtain a positive electrode active layer slurry;

[0141] (2) applying the safety primer slurry to the first functional surface 11 of the active layer area of ​​the aluminum foil, and drying to obtain the safety primer 201 of the first functional surface 11; applying the positive electrode active layer slurry to the safety primer 201 of the first functional surface 11 of the aluminum foil, and drying to obtain the positive electrode active layer 202 of the first functional surface 11; applying the second ceramic layer slurry to the first functional surface 11 of the empty foil area at the tail of the aluminum foil, and drying to obtain the single-sided coated positive electrode sheet;

[0142] (3) Use laser drilling equipment to press Figure 3 The second functional surface 12 of the aluminum foil is punched at the preset first region 101 to form a recessed structure 3, and no laser punching is performed in the second region. The distribution density of the second region is m=0, wherein the first region size A1=90%A, B1=B, C1=L4, the opening size L3 of the recessed structure 3 is 50 μm, the distance L4 between the opening centers of adjacent recessed structures 3 is 200 μm, the depth d2 of the recessed structure 3 is 7-9 μm, and the thickness d1 of the positive electrode current collector 1 is 9 μm;

[0143] (4) applying the safety primer slurry to the second functional surface 12 of the active layer area of ​​the aluminum foil, and drying to obtain the safety primer 201 of the second functional surface 12; applying the positive electrode active layer slurry to the safety primer 201 of the second functional surface 12 of the aluminum foil, and drying to obtain the positive electrode active layer 202 of the second functional surface 12; applying the ceramic layer slurry to the second functional surface 12 of the empty foil area at the tail of the aluminum foil, and drying to form a ceramic layer 203, thereby obtaining an initial positive electrode membrane;

[0144] (5) After rolling and cutting the initial positive electrode film, Figure 3 The positive electrode ear 5 is welded at the preset second area 102 position in a manner, wherein F=5 mm, to obtain a positive electrode sheet.

[0145] Among them, the relevant data of the positive electrode are shown in Table 1.

[0146] The positive electrode sheet and positive current collector of Example 1 were tested by 3D microscope, and the results are shown in Fig.10 and Fig.11 .

[0147] Example 2

[0148] The preparation process is basically the same as that of Example 1, except that, in the process of preparing the positive electrode sheet, the material of the safety primer layer 201 is different. Specifically, the preparation of the safety primer layer slurry is as follows: titanium dioxide, aluminum oxide, conductive carbon black (SP), polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) in a mass ratio of 84:10:1:5 are mixed, and the safety primer layer slurry of this embodiment is obtained after stirring and mixing evenly; the safety primer layer slurry of Example 1 is replaced by the safety primer layer slurry of this embodiment, and 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, and other conditions remain unchanged, to obtain the battery of this example.

[0150] Among them, the relevant data of the positive electrode are shown in Table 1.

[0151] Example 3

[0152] The preparation process is basically the same as that of Example 1, except that, in the process of preparing the positive electrode sheet, the material of the safety primer layer 201 is different. Specifically, the preparation of the safety primer layer slurry is as follows: titanium dioxide, polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) are mixed in a mass ratio of 97:3, and stirred to mix evenly to obtain the safety primer layer slurry of this embodiment; the safety primer layer slurry of Example 1 is replaced by the safety primer layer slurry of this embodiment, and other conditions remain unchanged to obtain the positive electrode sheet of this embodiment;

[0153] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example, and other conditions remain unchanged, to obtain the battery of this example.

[0154] Among them, the relevant data of the positive electrode are shown in Table 1.

[0155] Example 4

[0156] The preparation process is basically the same as that of Example 1, except that: during the preparation of the positive electrode sheet, the position and parameters of the punching process are adjusted to obtain a current collector such as Figure 4 In the positive electrode sheet shown, the distribution density of the recessed structures in the first region of the positive electrode sheet is n, and the distribution density of the recessed structures in the second region is m, n>0, m>n in some parts, and m=0 in some parts.

[0157] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example, and other conditions remain unchanged, to obtain the battery of this example.

[0158] Among them, the relevant data of the positive electrode are shown in Table 1.

[0159] Example 5

[0160] The preparation process is basically the same as that of Example 1, except that: during the preparation of the positive electrode sheet, the position and parameters of the punching process are adjusted to obtain a current collector such as Figure 5 In the positive electrode sheet shown, the distribution density of the recessed structures in the first region of the positive electrode sheet is n, and the distribution density of the recessed structures in the second region is m, where n>0 and m=0.

[0161] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example, and other conditions remain unchanged, to obtain the battery of this example.

[0162] Among them, the relevant data of the positive electrode are shown in Table 1.

[0163] Example 6

[0164] The preparation process is basically the same as that of Example 1, except that: during the preparation of the positive electrode sheet, the position and parameters of the punching process are adjusted to obtain a current collector such as Figure 6 In the positive electrode sheet shown, the distribution density of the recessed structures in the first region of the positive electrode sheet is n, and the distribution density of the recessed structures in the second region is m, where n>0 and m=0.

[0165] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example, and other conditions remain unchanged, to obtain the battery of this example.

[0166] Among them, the relevant data of the positive electrode are shown in Table 1.

[0167] Example 7

[0168] The preparation process is basically the same as that of Example 1, except that: during the preparation of the positive electrode sheet, the position and parameters of the punching process are adjusted to obtain a current collector such as Figure 7 In the positive electrode sheet shown, the distribution density of the recessed structures in the first region of the positive electrode sheet is n, and the distribution density of the recessed structures in the second region is m, n>0, m>n in some parts, and m=0 in some parts.

[0169] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example, and other conditions remain unchanged, to obtain the battery of this example.

[0170] Among them, the relevant data of the positive electrode are shown in Table 1.

[0171] Example 8

[0172] The preparation process is basically the same as that of Example 1, except that: during the preparation of the positive electrode sheet, the position and parameters of the punching process are adjusted to obtain a current collector such as Figure 8 In the positive electrode sheet shown, the distribution density of the recessed structures in the first region of the positive electrode sheet is n, and the distribution density of the recessed structures in the second region is m, where n>0 and m=0.

[0173] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example, and other conditions remain unchanged, thereby obtaining the battery of this example.

[0174] Among them, the relevant data of the positive electrode are shown in Table 1.

[0175] Example 9

[0176] The preparation process is basically the same as that of Example 1, except that: in the preparation process of the positive electrode sheet, the parameters of the punching process are adjusted to obtain the following Figure 3 In the positive electrode sheet shown, the distribution density of the recessed structures in the first region of the positive electrode sheet is n, and the distribution density of the recessed structures in the second region is m, where n>0 and m=0.

[0177] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example, and other conditions remain unchanged, to obtain the battery of this example.

[0178] Among them, the relevant data of the positive electrode are shown in Table 1.

[0179] Example 10

[0180] The preparation process is basically the same as that of Example 4, except that: in the preparation process of the positive electrode sheet, the parameters of the punching process are adjusted to obtain a current collector such as Figure 4 In the positive electrode sheet shown, the distribution density of the recessed structures in the first region of the positive electrode sheet is n, and the distribution density of the recessed structures in the second region is m, n>0, m>n in some parts, and m=0 in some parts.

[0181] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example, and other conditions remain unchanged, to obtain the battery of this example.

[0182] Among them, the relevant data of the positive electrode are shown in Table 1.

[0183] Embodiment 11

[0184] The preparation process is basically the same as that of Example 1, except that: in the preparation process of the positive electrode sheet, the parameters of the punching process are adjusted to obtain a current collector such as Figure 3 In the positive electrode sheet shown, the distribution density of the recessed structures in the first region of the positive electrode sheet is n, and the distribution density of the recessed structures in the second region is m, where n>0 and m=0.

[0185] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example, and other conditions remain unchanged, to obtain the battery of this example.

[0186] Among them, the relevant data of the positive electrode are shown in Table 1.

[0187] Example 12

[0188] The preparation process is basically the same as that of Example 1, except that: in the preparation process of the positive electrode sheet, the parameters of the punching process are adjusted to obtain a current collector such as Figure 3 In the positive electrode sheet shown, the distribution density of the recessed structures in the first region of the positive electrode sheet is n, and the distribution density of the recessed structures in the second region is m, where n>0 and m=0.

[0189] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example, and other conditions remain unchanged, to obtain the battery of this example.

[0190] Among them, the relevant data of the positive electrode are shown in Table 1.

[0191] Example 13

[0192] The preparation process is basically the same as that of Example 1, except that: in the preparation process of the positive electrode sheet, the parameters of the punching process are adjusted to obtain a current collector such as Figure 3 In the positive electrode sheet shown, the distribution density of the recessed structures in the first region of the positive electrode sheet is n, and the distribution density of the recessed structures in the second region is m, where n>0 and m=0.

[0193] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example, and other conditions remain unchanged, to obtain the battery of this example.

[0194] Among them, the relevant data of the positive electrode are shown in Table 1.

[0195] Embodiment 14

[0196] The preparation process is basically the same as that of Example 1, except that: in the preparation process of the positive electrode sheet, the parameters of the punching process are adjusted to obtain a current collector such as Figure 3 In the positive electrode sheet shown, the distribution density of the recessed structures in the first region of the positive electrode sheet is n, and the distribution density of the recessed structures in the second region is m, where n>0 and m=0.

[0197] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example, and other conditions remain unchanged, to obtain the battery of this example.

[0198] Among them, the relevant data of the positive electrode are shown in Table 1.

[0199] Embodiment 15

[0200] The preparation process is basically the same as that of Example 1, except that: in the preparation process of the positive electrode sheet, the parameters of the punching process are adjusted to obtain a current collector such as Figure 3 In the positive electrode sheet shown, the distribution density of the recessed structures in the first region of the positive electrode sheet is n, and the distribution density of the recessed structures in the second region is m, where n>0 and m=0.

[0201] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example, and other conditions remain unchanged, to obtain the battery of this example.

[0202] Among them, the relevant data of the positive electrode are shown in Table 1.

[0203] Example 16

[0204] The preparation process is basically the same as that of Example 1, except that: in the preparation process of the positive electrode sheet, the parameters of the punching process are adjusted to obtain a current collector such as Figure 3 In the positive electrode sheet shown, the distribution density of the recessed structures in the first region of the positive electrode sheet is n, and the distribution density of the recessed structures in the second region is m, where n>0 and m=0.

[0205] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example, and other conditions remain unchanged, to obtain the battery of this example.

[0206] Among them, the relevant data of the positive electrode are shown in Table 1.

[0207] Comparative Example 1

[0208] The preparation process is basically the same as that of Example 1, except that, in the preparation process of the positive electrode sheet, step (3) is omitted, that is, the aluminum foil is not punched, and other conditions remain unchanged, to obtain the positive electrode sheet of this embodiment;

[0209] During the preparation of the battery, the positive electrode sheet of Example 1 is replaced with the positive electrode sheet of this example, and other conditions remain unchanged, to obtain the battery of this example.

[0210] Comparative Example 2

[0211] The preparation process is basically the same as that of Example 2, except that, in the preparation process of the positive electrode sheet, step (3) is omitted, that is, the aluminum foil is not punched, and other conditions remain unchanged, to obtain the positive electrode sheet of this embodiment;

[0212] During the preparation of the battery, the positive electrode sheet of Example 2 is replaced by the positive electrode sheet of this example, and other conditions remain unchanged, to obtain the battery of this example.

[0213] Table 1

[0214]

[0215]

[0216] Test example

[0217] The preparation of a battery using the positive electrode sheets provided in all the embodiments and comparative examples specifically includes the following steps:

[0218] 1. Preparation of negative electrode sheets: Graphite, styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC) and deionized water in a mass ratio of 97:1.5:1.5 are mixed and stirred evenly to obtain a negative electrode coating slurry; the negative electrode coating slurry is applied to the surface of the negative electrode current collector, and the negative electrode sheets are obtained after drying, rolling and slitting.

[0219] 2. Prepare the battery: stack the positive electrode sheet, the separator, and the negative electrode sheet in sequence and wind them up to obtain a winding core; wherein the opening end of the recessed structure 3 faces a side away from the center of the winding core;

[0220] 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.

[0221] The prepared lithium battery was tested.

[0222] 1. Foreign body extrusion test method

[0223] Take a fully charged battery and keep the test environment temperature at 25±2℃. Place a screw with a diameter of 2mm and a length of 3.5mm in the middle of the battery. Use an extruder to extrude the battery vertically at a speed of 15mm / s. Stop when the pressure reaches 13KN or the extrusion stroke reaches 10mm. Keep for 100s. If the battery does not catch fire or explode, the test is considered passed. The number of passes / the number of tests is the foreign body extrusion pass rate. The number of tests is (20). The test results are shown in Table 2.

[0224] 2. Acupuncture test method

[0225] Take a fully charged battery, keep the test environment temperature at 25±2℃, use a 3mm steel needle to pierce the center of the battery vertically at a speed of 0.1mm / s, and keep it for 5 minutes. If the battery does not catch fire or explode, it is considered to have passed the test. The number of passes / the number of tests is the screw test pass rate. The number of tests is (30). The test results are shown in Table 2.

[0226] Table 2

[0227] serial number Foreign body extrusion passing rate Acupuncture pass rate Example 1 14 / 20 21 / 30 Example 2 12 / 20 20 / 30 Example 3 13 / 20 27 / 30 Example 4 8 / 20 15 / 30 Example 5 11 / 20 18 / 30 Example 6 9 / 20 15 / 30 Example 7 11 / 20 18 / 30 Example 8 10 / 20 17 / 30 Example 9 12 / 20 17 / 30 Example 10 11 / 20 18 / 30 Embodiment 11 14 / 20 20 / 30 Example 12 6 / 20 12 / 30 Embodiment 13 6 / 20 12 / 30 Embodiment 14 14 / 20 20 / 30 Embodiment 15 13 / 20 21 / 30 Example 16 14 / 20 18 / 30 Comparative Example 1 0 / 20 9 / 30 Comparative Example 2 0 / 20 8 / 30

[0228] By comparing the embodiments and comparative examples, it can be seen that the lithium-ion battery manufactured using the pole piece of the utility model has a higher pass rate in the foreign body extrusion test and the needle puncture test, indicating that the battery has better safety performance.

[0229] For Examples 11, 14, and 15, although the lithium-ion batteries manufactured using the pole pieces provided in Examples 11, 14, and 15 have a higher pass rate in the foreign body extrusion test and the needle penetration test, the manufacturing difficulty becomes greater or the yield rate is significantly reduced.

[0230] It should be noted here that the numerical values ​​and numerical ranges involved in the embodiments of the present invention are approximate values. Due to the influence of the manufacturing process, there may be a certain range of errors, which can be considered negligible by those skilled in the art.

[0231] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the utility model.

[0232] The above describes the implementation methods of the present invention. However, the present invention is not limited to the above implementation methods. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A pole piece, characterized in that: It comprises a stacked current collector, a safety primer layer and an active layer; the current collector is provided with N recessed structures, the openings of the recessed structures are located on the functional surface of the current collector, and N≥1; at least part of the safety primer layer is embedded in the recessed structure of the current collector.

2. The pole piece according to claim 1, characterized in that: The current collector includes first regions and second regions that are alternately arranged; In the first region, the distribution density of the recessed structures is n, where n>0; In the second region, the distribution density of the recessed structures is m, where m=0 or m>n.

3. The pole piece according to claim 2, characterized in that: m=0, the first region and the second region are alternately distributed along the length direction of the current collector, the size of the second region in the length direction of the current collector is D2, and the distance between the opening centers of adjacent recessed structures in the first region in the length direction of the current collector is L2, wherein D2≥L2; or, m=0, the first region and the second region are alternately distributed along the width direction of the current collector, the size of the second region in the width direction of the current collector is D2, and the distance between the opening centers of adjacent recessed structures in the first region in the length direction of the current collector is L2, wherein D2≥L2.

4. The pole piece according to claim 2, characterized in that: m>n, the first region and the second region are alternately distributed along the length direction of the current collector, the size of the second region in the length direction of the current collector is D1, and the distance between the opening centers of adjacent recessed structures in the first region in the length direction of the current collector is L1, wherein D1≥L1×2; or, m>n, the first region and the second region are alternately distributed along the width direction of the current collector, the size of the second region in the width direction of the current collector is D1, and the distance between the opening centers of adjacent recessed structures in the first region in the width direction of the current collector is L1, wherein D1≥L1×2.

5. The pole piece according to claim 4, characterized in that: The size of the first region in the length direction of the current collector is A1, the size of the current collector in the length direction is A, and A1≥10%A; The size of the first region in the width direction of the current collector is B1, the size of the current collector in the width direction is B, and B1≥10%B.

6. The pole piece according to claim 1, characterized in that: The size of the opening of the recessed structure is L3, and the distance between the centers of the openings of adjacent recessed structures is L4, wherein 1<L4 / L3≤10; And / or, the thickness of the current collector is d1, the depth of the recessed structure is d2, and the following conditions are satisfied: 0.2≤d2 / d1≤1; And / or, the distance between the opening centers of adjacent recessed structures is L4, and the distance between the recessed structure and the edge of the current collector in the width direction is C1, satisfying: C1≥0.5×L4; And / or, the size of the opening of the recessed structure is L3, the distance between the recessed structure and the edge of the current collector is C1, and L3 / C1≥0 is satisfied; And / or, the edge of the opening of the recessed structure has a convex structure, the convex structure has a width w and a height h1, wherein 1 μm≤w≤L3×2, 0.1 μm≤h1≤L3×2.

7. The pole piece according to claim 6, characterized in that: The L3 is 10-300 μm; L4 is 10-10000 μm, d2 is 1-20 μm, d1 is 4-20 μm, C1 is 5-5000 μm, w is 1-600 μm, and h1 is 0.1-600 μm.

8. The pole piece according to claim 1, characterized in that: Also includes a pole ear, the pole ear is electrically connected to the current collector; The distance between the edge of the opening of the recessed structure and the edge of the tab is F, where F≥1 mm.

9. The pole piece according to claim 1, characterized in that: It also includes a protective layer; Along the length direction of the current collector, the protective layer is adjacent to the safety primer layer and covers at least a portion of the functional surface of the current collector, and the protective layer is at least partially embedded in the recessed structure; Alternatively, along the length direction of the current collector, the protective layer is adjacent to the active layer and covers at least a portion of the surface of the safety primer layer away from the current collector; The material of the protective layer includes at least one of a first material or a modified product of the first material, wherein the first material includes at least one of 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, lithium nickel cobalt aluminum oxide, lithium titanate, aluminum oxide, boehmite, titanium dioxide, zirconium oxide, silicon dioxide and a conductive polymer.

10. The pole piece according to claim 1, characterized in that: The material of the safety primer layer includes at least one of a first material or a modified product of the first material, wherein the first material includes at least one of 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 rich manganese-based material, lithium nickel cobalt aluminum oxide, lithium titanate, aluminum oxide, boehmite, titanium dioxide, zirconium oxide, silicon dioxide and a conductive polymer; The material of the active layer includes at least one of 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 rich manganese-based material, and lithium nickel cobalt aluminum oxide.

11. The pole piece according to claim 1, characterized in that: The pole piece is a positive pole piece.

12. A battery, characterized in that: A pole piece comprising any one of claims 1 to 11.

13. The battery according to claim 12, characterized in that The battery comprises an electrode assembly and a shell, wherein the electrode assembly comprises the electrode sheet, the diaphragm, and the second electrode sheet which are stacked and wound. The pole piece also includes a protective layer; Along the length direction of the current collector, the protective layer is adjacent to the safety primer layer and covers at least a portion of the functional surface of the current collector, and the protective layer is at least partially embedded in the recessed structure; Alternatively, along the length direction of the current collector, the protective layer is adjacent to the active layer and covers at least a portion of the surface of the safety primer layer away from the current collector; Along the winding direction, the protective layer is located at the tail of the winding core of the electrode assembly.

14. The battery according to claim 12, characterized in that The opening end of the recessed structure of the pole piece faces a side away from the center of the battery cell.

Images