Battery

Abstract

The utility model provides a battery which comprises a first pole piece, the first pole piece comprises a straight section, the straight section is provided with a punching area, the punching area is provided with at least one row of hole structures, each row of hole structures comprises at least two hole structures, and the at least two hole structures are arranged in the same direction; the extension size L1 of the pore structure along the first direction and the extension size W1 of the pore structure along the second direction meet the following conditions: L1 / W1 is greater than or equal to 1 and less than 10; and in the second direction, the punching area is arranged in the middle of the first pole piece. According to the first pole piece, the safety of the battery is improved.

Description

TECHNICAL FIELD

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

[0002] When a lithium ion battery is subjected to foreign matter extrusion, the temperature of the lithium ion battery is likely to rise rapidly in a short time, and eventually combustion and explosion occur.

[0003] When a lithium ion battery is short-circuited, four kinds of contacts can be generated: positive active material and negative active material contact, positive active material and negative current collector contact, positive current collector and negative active material contact, and positive current collector and negative current collector contact. Among them, the positive current collector and the negative active material contact are the most dangerous, which can cause the battery to burn violently in a short time. Therefore, how to reduce the probability of short circuit of the lithium ion battery when it is mechanically damaged is a problem to be solved. UTILITY MODEL CONTENT

[0004] Therefore, the application provides a battery to solve the problems in the prior art.

[0005] The battery provided by the application includes a first pole piece, the first pole piece includes a flat section, the flat section has a punching area, the punching area has at least one row of hole structures, the at least one row of hole structures includes at least two hole structures, and the at least two hole structures are arranged in the same direction.

[0006] The extension size L1 of a single hole structure in the first direction and the extension size W1 of the single hole structure in the second direction satisfy 1≤L1 / W1<10.

[0007] In the second direction, the punching area is arranged centrally on the first pole piece.

[0008] In a possible implementation, the arrangement direction of the hole structures is consistent with the first direction.

[0009] In a possible implementation, the extension size L1 of a single hole structure in the first direction and the extension size W1 of the single hole structure in the second direction further satisfy:

[0010] 50μm≤W1<L1<2000μm.

[0011] In a possible implementation, in the second direction, the punching area has at least two rows of hole structures, and a second spacing W2 is arranged between the two adjacent rows of hole structures, and in the first direction, a first spacing L2 is arranged between the two adjacent hole structures in the same row of hole structures.

[0012] The first spacing L2 and the second spacing W2 satisfy 1≤W2 / L2<500; and / or, the first spacing L2 and the second spacing W2 further satisfy 10μm<L2≤W2<5000μm.

[0013] In a possible implementation, the extension size L1 of the single hole structure along the first direction and the first pitch L2 satisfy: 0.2 < L1 / L2 < 10;

[0014] And / or, the extension size W1 of the single hole structure along the second direction and the second pitch W2 satisfy: 0.5 < W2 / W1 < 100.

[0015] In a possible implementation, in the first direction, the extension size L3 of the punched area and the extension size L4 of the first tab satisfy: 70% ≤ L3 / L4 ≤ 100%;

[0016] And / or, in the second direction, the extension size W3 of the punched area and the extension size W4 of the first tab satisfy: 30% ≤ W3 / W4 ≤ 100%.

[0017] In a possible implementation, the first tab further includes a circular arc segment, which is connected to opposite sides of the flat segment along the first direction;

[0018] In the first direction, the extension size L3 of the punched area and the extension size L4 of the first tab satisfy: 80% ≤ L3 / L4 ≤ 100%;

[0019] And / or, in the second direction, the extension size W3 of the punched area and the extension size W4 of the first tab satisfy: 30% ≤ W3 / W4 ≤ 100%.

[0020] In a possible implementation, the area S1 of all hole structures and the area S2 of the first tab satisfy: 0.1% ≤ S1 / S2 ≤ 20%;

[0021] Wherein, the area S1 of all hole structures = a(1) + a(2) + … + a(n), n is the number of hole structures.

[0022] In a possible implementation, the first tab includes a first current collector and a first active material layer, the first active material layer is arranged on at least one side of the first current collector, and the hole structure is arranged on at least one of the first active material layer and the first current collector.

[0023] In a possible implementation, the hole structure is arranged on the first active material layer, the extension size H1 of the hole structure along the third direction and the extension size H2 of the first active material layer along the third direction satisfy: 0.3 ≤ H1 / H2 ≤ 1;

[0024] Or, the hole structure is arranged on the first current collector, the extension size H1 of the hole structure along the third direction and the extension size H3 of the first current collector along the third direction satisfy: 0.5 ≤ H1 / H3 ≤ 1;

[0025] Alternatively, the hole structure penetrates through opposite surfaces of the first tab.

[0026] In a possible implementation, the shape of the hole structure includes at least one of a circle, an ellipse, a diamond, and a rectangle.

[0027] In a possible implementation, the first tab further includes a non-punching area, a ratio of the tensile strength of the punching area to the tensile strength of the non-punching area is greater than or equal to 50% and less than or equal to 96%;

[0028] And / or, a ratio of the elongation at break of the punching area to the elongation at break of the non-punching area is greater than or equal to 50% and less than or equal to 98%.

[0029] In a possible implementation, the tensile strength of the punching area is greater than or equal to 10 Mpa and less than or equal to 25 Mpa;

[0030] And / or, the tensile strength of the non-punching area is greater than or equal to 20 Mpa and less than or equal to 35 Mpa;

[0031] And / or, the elongation at break of the punching area is greater than or equal to 1% and less than or equal to 3%;

[0032] And / or, the elongation at break of the punching area is greater than or equal to 2% and less than or equal to 4.5%.

[0033] The battery provided by the embodiments of the present application includes a first tab, the first tab includes a flat section, the flat section includes a punching area, and the punching area includes a hole structure. By providing the punching area on the first tab and the hole structure in the punching area, the strength of the first tab is purposefully reduced. The hole structure has an extension size L1 in a first direction and an extension size W1 in a second direction, and the extension size L1 in the first direction and the extension size W1 in the second direction satisfy 1≤L1 / W1<10. The hole structure reduces the strength of the first tab in the first direction or in the arrangement direction of the plurality of hole structures. When the first tab is mechanically damaged, the first tab is broken along the first direction or along the arrangement direction of the hole structure. The fracture of the first tab is relatively neat, thereby reducing the short-circuit point when the first tab is broken. The punching area is centrally arranged on the first tab in the second direction, so as to facilitate the heavy impact test of the first tab and avoid the edge of the first tab from falling off powder and lithium precipitation. Thus, the first tab of the embodiments of the present application improves the safety of the battery.

[0034] In addition to the technical problems solved by the embodiments of the present application described above, the technical features constituting the technical solutions, and the beneficial effects brought by these technical features, the other technical problems solved by the battery provided by the present application, the other technical features included in the technical solutions, and the beneficial effects brought by these technical features will be further described in detail in the specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0036] Figure 1 The structural schematic diagram of the battery provided by the embodiments of the present application is shown in the following figure.

[0037] Figure 2 The structural schematic diagram of the first pole piece in the battery provided by the embodiments of the present application is shown in the following figure.

[0038] Figure 3 The structural schematic diagram of the first pole piece in the battery provided by the embodiments of the present application is shown in the following figure.

[0039] Figure 4 The structural schematic diagram of the first pole piece in the battery provided by the embodiments of the present application is shown in the following figure.

[0040] Explanation of reference signs:

[0041] 100-first pole piece; 110-punching area; 111-hole structure; 120-non-punching area; 130-first current collector; 140-first active material layer; 200-first tab. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the present application more clear, the following will describe the technical solutions of the embodiments of the present application in more detail by combining the drawings of the preferred embodiments of the present application. In the drawings, the same or similar reference signs represent the same or similar components or components with the same or similar functions throughout. The described embodiments are some embodiments of the present application, not all embodiments. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application, and cannot be understood as limiting the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort belong to the scope of protection of the present application. The embodiments of the present application will be described in detail below by combining the drawings.

[0043] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood in a broad sense, for example, it can be fixed connection, or indirect connection through intermediate medium, or internal communication of two elements or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0044] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0045] The terms "first", "second", "third" (if any) in the specification and claims of the present application and the above drawings are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0046] In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or display that includes a series of steps or units does not have to be limited to only those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or displays.

[0047] When a lithium ion battery short-circuits, four types of contacts can occur: positive active material and negative active material contact, positive active material and negative current collector contact, positive current collector and negative active material contact, and positive current collector and negative current collector contact. Among them, the contact between the positive current collector and the negative active material is the most dangerous, which can cause the battery to burn violently in a short time. Therefore, how to reduce the probability of short-circuit of lithium ion battery when it is mechanically damaged is a problem that needs to be solved.

[0048] In view of the above problems, the embodiments of the present application provide a battery, by setting a punching area on the flat section of the first pole piece, setting at least one row of hole structures in the punching area, and the hole structures are in an elongated shape, so that when the first pole piece is subjected to extrusion by foreign matter, impact by heavy objects, etc., the first pole piece breaks along the arrangement direction of the hole structures, and the fracture of the first pole piece is relatively neat, thereby reducing the short-circuit points when the first pole piece breaks.

[0049] The specific embodiments of the battery provided by the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0050] Reference Figures 1 to 3As shown, the battery provided by the embodiments of the present application includes a first pole piece 100, the first pole piece 100 includes a flat section, the flat section has a punching area 110, the punching area 110 has at least one row of hole structures 111, and the at least one row of hole structures 111 includes at least two hole structures 111, and the at least two hole structures 111 are arranged in the same direction.

[0051] The extension size L1 of the hole structure 111 in the first direction and the extension size W1 of the hole structure 111 in the second direction satisfy: 1≤L1 / W1<10.

[0052] The first direction can be the length direction of the flat section, and the first direction can refer to the X direction in FIG. 1. Figures 1 to 3 The second direction can be the width direction of the flat section, and the second direction can refer to the Y direction in FIG. 1. Figures 1 to 3

[0053] It can be understood that the battery can further include a second pole piece and a diaphragm, one of the first pole piece 100 and the second pole piece is a positive electrode, and the other is a negative electrode. For example, the first pole piece 100 is a negative electrode, and the second pole piece is a positive electrode, or the first pole piece 100 is a positive electrode, and the second pole piece is a negative electrode.

[0054] The first pole piece 100, the diaphragm, and the second pole piece are stacked in sequence to form a laminated battery cell, or the first pole piece 100, the diaphragm, and the second pole piece are sequentially laminated and then wound to form a wound battery cell. If it is a laminated battery cell, the first pole piece 100 only includes a flat section, and if it is a wound battery cell, the first pole piece 100 includes a flat section and a circular arc section.

[0055] It is worth noting that no matter which form of battery cell, the punching area 110 can be arranged on the flat section of the first pole piece 100, the punching area 110 can be arranged with one row or multiple rows of hole structures 111, and each row of hole structures 111 can include two or more hole structures 111. Therefore, compared with the non-punching area 120, the mechanical strength of the punching area 110 is lower due to the arrangement of the hole structures 111. In the first direction, the extension size L1 of the hole structure 111 is larger, and in the second direction, the extension size W1 of the hole structure 111 is smaller, and L1 and W1 satisfy: 1<L1 / W1<100. In this way, the hole structure 111 can be elongated, and the first pole piece 100 is more likely to be damaged in the first direction or the arrangement direction of the hole structure 111 when it encounters mechanical damage, and the first pole piece 100 is broken along the first direction or the arrangement direction of the hole structure 111, so that the fracture of the first pole piece 100 is more regular, thereby reducing the short-circuit points when the first pole piece 100 is broken, and thus improving the safety of the battery.

[0056] ​Alternatively, the extension size L1 of the hole structure 111 can also be equal to the extension size W1 of the hole structure 111, and in the arrangement, the strength of the first pole piece 100 in the first direction can be effectively reduced by reasonably setting the spacing of the adjacent hole structures 111.

[0057] Since the steel bar needs to fall on the central part of the first pole piece 100 when the heavy object impact test is performed, and the length direction of the steel bar is along the first direction, in some embodiments, the punching area 110 can be centrally arranged in the second direction, so that the distance between the punching area 110 and the two side edges of the first pole piece 100 in the second direction is substantially equal, thereby ensuring that the steel bar falls within the punching area 110.

[0058] It should be noted that the two sides of the first pole piece 100 in the second direction, that is, the two sides of the first pole piece 100 in the width direction, arranging the punching area 110 on one side or both sides of the first pole piece 100 in the second direction is easy to cause the edge of the first pole piece 100 to fall off, and when the first pole piece 100 is a negative pole piece, arranging the hole structure 111 on the edge of the first pole piece 100 reduces the lithium ion intercalation site of the edge of the first pole piece 100, thereby easily causing the battery to precipitate lithium.

[0059] For example, the first pole piece 100 is evenly divided into N equal parts in the second direction, when N is an odd number, the punching area 110 is located in the (N+1) / 2 equal part, when N is an even number, the punching area 110 is located in the N / 2 equal part or the (N+1) / 2 equal part, or the punching area 110 is located in the N / 2 equal part and the (N+1) / 2 equal part at the same time.

[0060] The battery provided by the embodiments of the present application includes the first pole piece 100, the first pole piece 100 includes a flat section, the flat section includes a punching area 110, the punching area 110 includes a hole structure 111, by arranging the punching area 110 on the first pole piece 100, and arranging a plurality of hole structures 111 on the punching area 110, the strength of the first pole piece 100 is purposefully reduced, by making the extension size L1 of the hole structure 111 in the first direction and the extension size W1 of the hole structure 111 in the second direction satisfy: 1≤L1 / W1<10, so that the hole structure 111 reduces the strength of the first pole piece 100 in the first direction or the arrangement direction of the single-row hole structure 111, thereby making the first pole piece 100 break along the first direction or the arrangement direction of the hole structure 111 when the first pole piece 100 is subjected to mechanical damage, and the fracture of the first pole piece 100 is relatively neat, thereby reducing the short-circuit point when the first pole piece 100 breaks, thereby the first pole piece 100 of the embodiments of the present application improves the safety of the battery.

[0061] In some embodiments, when the punching area 110 is provided with only one row of hole structures 111, the arrangement direction of the hole structures 111 can be at an angle with the first direction, and the hole structures 111 also satisfy 1≤L1 / W1<10, and the strength of the first pole piece 100 is uniformly reduced along the arrangement direction of the hole structures 111, so that the first pole piece 100 breaks along the arrangement direction of the hole structures 111 when it breaks.

[0062] In some embodiments, the arrangement direction of the hole structures 111 is consistent with the first direction. In this arrangement, the hole structures 111 can be provided in one row or multiple rows, and the arrangement direction of the single row of hole structures 111 is along the first direction, so that the first pole piece 100 breaks along the first direction when the heavy impact test is performed on the first pole piece 100, thereby reducing the short-circuit points of the fracture and improving the pass rate of the test.

[0063] In a possible implementation, the extension size L1 of the hole structures 111 along the first direction and the extension size W1 of the hole structures 111 along the second direction also satisfy 50 μm≤W1<L1<2000 μm.

[0064] It should be noted that the neatness of the fracture of the first pole piece 100 is also related to the size of the hole structures 111 and the density of the hole structures 111. If the extension size of the punching area 110 along the first direction is unchanged, in the single row of hole structures 111, the smaller the extension size L1 of the hole structures 111 along the first direction, the more the number of each row of hole structures 111, which can effectively reduce the strength of the first pole piece 100 to a preset range, but considering the processability, the extension size L1 of the hole structures 111 along the first direction cannot be too small, and therefore, considering this, the extension size L1 of the hole structures 111 along the first direction can be set to 50 μm to 2000 μm.

[0065] When the extension size of the punching area 110 along the second direction is unchanged, the smaller the extension size W1 of the hole structures 111 along the second direction, the more the number of rows of hole structures 111, which can effectively reduce the strength of the first pole piece 100 to a preset range, and considering the machining performance when the holes are punched, the extension size W1 of the hole structures 111 along the second direction can be set to 50 μm to 2000 μm.

[0066] In addition, the extension size L1 of the hole structures 111 along the first direction and the extension size W1 of the hole structures 111 along the second direction need to satisfy W1<L1, so that the hole structures 111 are in an elongated shape, and therefore, the extension size L1 of the hole structures 111 along the first direction and the extension size W1 of the hole structures 111 along the second direction can satisfy 50 μm≤W1<L1<2000 μm.

[0067] In a possible implementation, the punching area 110 has at least two rows of hole structures 111, and the second spacing W2 is between two adjacent rows of hole structures 111, and the first spacing L2 is between two adjacent hole structures 111 in the same row, and the first spacing L2 and the second spacing W2 satisfy: 1≤W2 / L2<500.

[0068] It should be noted that the first spacing L2 can be the center spacing of two adjacent hole structures 111 in the first direction, that is, the center of one hole structure 111 to the center of another hole structure 111, or the first spacing L2 can also be the spacing between the two ends of two adjacent hole structures 111 in the first direction.

[0069] For example, when the hole structures 111 are arranged in the first direction and multiple rows of hole structures 111 are arranged in the second direction, the second spacing W2 is between two adjacent rows of hole structures 111, and the first spacing L2 is between two adjacent hole structures 111 in the first direction, and the first spacing L2 is smaller than the second spacing W2. In this way, in the second direction, the distance between adjacent hole structures 111 is relatively larger, and the first pole piece 100 can withstand a larger stress in this direction, and in the first direction, the distance between adjacent hole structures 111 is relatively smaller, and the hole structures 111 are arranged more densely, and the first pole piece 100 can withstand a smaller stress in this direction, thereby making the first pole piece 100 more likely to break along the first direction when mechanically damaged, that is, the fracture extends along the first direction. Moreover, the first spacing L2 is smaller than 50 times the second spacing W2, thereby facilitating the arrangement of a proper number of hole structures 111 in the punching area 110.

[0070] For example, the ratio W2 / L2 of the second spacing W2 to the first spacing L2 can be any one of 1.5, 2, 10, 100, 400 or within any two value ranges.

[0071] In a possible implementation, the first spacing L2 and the second spacing W2 also satisfy: 10 μm≤L2≤W2<5000 μm. In this way, the first spacing L2 is smaller than or equal to the second spacing W2, thereby making the hole structures 111 more densely arranged in the first direction, thereby making the first pole piece 100 more likely to break along the first direction when mechanically damaged, and also taking into account the processability and the density of the hole structures 111, thereby reducing the mechanical strength of the first pole piece 100 to a preset value.

[0072] Exemplarily, the first interval L2 can be any one of 10 μm, 100 μm, 1000 μm, 2000 μm, 5000 μm or within any two ranges. The second interval W2 can be any one of 10 μm, 50 μm, 500 μm, 1000 μm, 5000 μm or within any two ranges. As long as the first interval L2 is greater than or equal to the second interval W2.

[0073] It should be understood that, in the second direction, the plurality of hole structures 111 can be uniformly or non-uniformly spaced, and in the first direction, the plurality of hole structures 111 can be uniformly or non-uniformly spaced, which is not limited by the embodiments of the application.

[0074] In a possible implementation, the extension size L1 of the hole structure 111 in the first direction and the first interval L2 satisfy: 0.2 < L1 / L2 < 10. And / or, the extension size W1 of the hole structure 111 in the second direction and the second interval W2 satisfy: 0.5 < W2 / W1 < 100.

[0075] Exemplarily, the ratio L1 / L2 of the extension size L1 of the hole structure 111 in the first direction and the first interval L2 can be any one of 0.3, 0.4, 1, 5, 9 or within any two ranges. And / or, the ratio W2 / W1 of the second interval W2 and the extension size W1 of the hole structure 111 in the second direction can be any one of 0.55, 0.8, 2, 10, 90 or within any two ranges.

[0076] In this way, the mechanical strength of the first tab 100 in the first direction can be reduced, the first tab 100 can bear less stress in the first direction, and the first tab 100 can be broken along the first direction to form a fracture, thereby improving the uniformity of the fracture of the first tab 100 and improving the safety of the battery.

[0077] When the first tab 100 is made into a battery by using a lamination process, in the first direction, the extension size L3 of the punched area 110 and the extension size L4 of the first tab 100 satisfy: 70%≤L3 / L4≤100%. And / or, in the second direction, the extension size W3 of the punched area 110 and the extension size W4 of the first tab 100 satisfy: 30%≤W3 / W4≤100%.

[0078] That is, in the first direction, the punching area 110 can cover most or all of the flat section, and in the second direction, the punching area 110 covers a small part or all of the flat section, so that the first tab 100 is lower in strength in the first direction than in the second direction, so that the first tab 100 is broken more evenly along the first direction. And also can ensure that when the heavy impact test is carried out, the steel rod used for testing can completely fall into the punching area 110.

[0079] In some embodiments, the first tab 100 further comprises a circular arc section connected to the opposite sides of the flat section along the first direction. In the first direction, the extension size L3 of the punching area 110 and the extension size L4 of the first tab 100 satisfy: 80%≤L3 / L4≤100%. And / or, in the second direction, the extension size W3 of the punching area 110 and the extension size W4 of the first tab 100 satisfy: 30%≤W3 / W4≤100%.

[0080] That is, in the winding type battery, the first tab 100 has a flat section and a circular arc section, the flat section is provided with a punching area 110, and the circular arc section can not be provided with a punching area 110, thereby avoiding reducing the mechanical properties of the circular arc section. Therefore, in the first direction, the extension size L3 of the punching area 110 and the extension size L4 of the first tab 100 satisfy: 80%≤L3 / L4≤100%, so as to ensure that the flat section of the first tab 100 is provided with sufficient hole structures 111. For example, Figure 1 The case of L3 / L4=100% is shown.

[0081] Wherein, the punching area 110 can be understood as the area enclosed by the plurality of hole structures 111, and the punching area 110 is provided with the hole structures 111, and the hole structures 111 need to have sufficient density to effectively reduce the mechanical strength of the flat section.

[0082] For example, referring to Figure 1 As shown, the first tab 100 has a punching area 110, the punching area 110 is provided with four rows of hole structures 111 along the second direction, and each row of hole structures 111 has 5 hole structures 111 in the first direction. In this way, the punching area 110 can be understood as the area enclosed by the four rows of hole structures 111.

[0083] In the first lug type battery, since the first tab 100 needs to reserve part of the blank area for processing into the first lug 200, the side of the first tab 100 close to the first lug 200 can not be provided with hole structures 111, and the hole structures 111 can be selected to be arranged at the middle of the first tab 100 and the side of the first tab 100 away from the first lug 200, thereby avoiding reducing the connection strength of the first lug 200.

[0084] In a possible implementation, the area S1 of all the hole structures 111 in the punching area 110 and the area S2 of the first tab 100 satisfy: 0.1%≤S1 / S2≤20%, where the area S1 of the hole structures 111=a(1)+a(2)+…+a(n), and n is the number of the hole structures 111.

[0085] In this way, the density of the hole structures 111 on the first tab 100 is effectively guaranteed, and the mechanical strength of the first tab 100 is effectively reduced to a preset range.

[0086] Referring to Figure 4 In a possible implementation, the first tab 100 includes a first current collector 130 and a first active material layer 140, the first active material layer 140 is arranged on at least one side of the first current collector 130, and the hole structures 111 are arranged in at least one of the first active material layer 140 and the first current collector 130.

[0087] In this way, no matter whether the hole structures 111 are arranged in the first current collector 130 or the first active material layer 140, or the hole structures 111 penetrate the first active material layer 140 and the first current collector 130, the hole structures 111 can effectively reduce the mechanical strength of the first tab 100. In addition, the first tab 100 is provided with the hole structures 111, and the degree of impregnation of the electrolyte to the first tab 100 is improved, and thus the dark spot or lithium precipitation phenomenon caused by poor impregnation of the active material is reduced, thereby improving the cycle performance of the battery.

[0088] In some embodiments, the hole structures 111 are arranged in the first active material layer 140, and the extension dimension H1 of the hole structures 111 along the third direction and the extension dimension H2 of the first active material layer 140 along the third direction satisfy: 0.3≤H1 / H2≤1.

[0089] Alternatively, in some embodiments, the hole structures 111 are arranged in the first current collector 130, and the extension dimension H1 of the hole structures 111 along the third direction and the extension dimension H3 of the first current collector 130 along the third direction satisfy: 0.5≤H1 / H3≤1. For example, Figure 4 H1 / H3=1 is shown, that is, the hole structures 111 penetrate the opposite two sides of the first current collector 130.

[0090] Alternatively, in some embodiments, the hole structures 111 penetrate the opposite two sides of the first tab 100.

[0091] For example, a ratio H1 / H2 of an extension size H1 of the hole structure 111 along the third direction to an extension size H2 of the first active material layer 140 along the third direction can be any one of or within any range of 0.3, 0.5, 0.6, 0.8, 1. Alternatively, a ratio H1 / H3 of the extension size H1 of the hole structure 111 along the third direction to an extension size H3 of the first current collector 130 along the third direction can be any one of or within any range of 0.5, 0.6, 0.7, 0.8, 1.

[0092] In this way, the hole structure 111 can have a certain depth, thereby effectively reducing the mechanical strength of the first pole piece 100. The third direction can refer to a Z direction in the coordinate system shown in FIG. 1. Figure 4

[0093] In one possible implementation, the shape of the hole structure 111 includes at least one of a circle, an ellipse, a rhombus, a rectangle, and an irregular polygon.

[0094] In this way, using any one or more of an ellipse, a rhombus, and a rectangle as the shape of the hole structure 111 can make the extension size L1 of the hole structure 111 along the first direction and the extension size W1 of the hole structure 111 along the second direction satisfy 1≤L1 / W1<10.

[0095] For example, in a single row of hole structures 111, the shape of each hole structure 111 can be the same, for example, the shape of each hole structure 111 is an ellipse, a rhombus, or a rectangle. In multiple rows of hole structures 111, the shape of each row of hole structures 111 can be the same or different, for example, the shape of one row of hole structures 111 is an ellipse, and the shape of another row of hole structures 111 is a rhombus or a rectangle.

[0096] ​It should be noted that for different shapes of the hole structure 111, for example, when the hole structure 111 is circular, the extension size L1 of the hole structure 111 along the first direction and the extension size W1 of the hole structure 111 along the second direction can both be understood as the diameter of the circle. Alternatively, when the hole structure 111 is elliptical, the extension size L1 of the hole structure 111 along the first direction can be understood as the length of the major axis of the ellipse, and the extension size W1 of the hole structure 111 along the second direction can be understood as the length of the minor axis of the ellipse. Alternatively, when the hole structure 111 is rhombic, the extension size L1 of the hole structure 111 along the first direction can be understood as the length of the diagonal of the rhombus in the direction, and the extension size W1 of the hole structure 111 along the second direction can be understood as the length of the diagonal of the rhombus in the direction. Alternatively, when the hole structure 111 is an irregular quadrilateral, the extension size L1 of the hole structure 111 along the first direction can be understood as the maximum size of the irregular quadrilateral in the direction, and the extension size W1 of the hole structure 111 along the second direction can be understood as the maximum size of the irregular quadrilateral in the direction.

[0097] In a possible implementation, the first pole piece 100 further comprises a non-punching area 120, and a ratio of the tensile strength of the punching area 110 to the tensile strength of the non-punching area 120 is greater than or equal to 50% and less than or equal to 96%. And / or, a ratio of the breaking elongation of the punching area 110 to the breaking elongation of the non-punching area 120 is greater than or equal to 50% and less than or equal to 98%.

[0098] That is, the mechanical strength, such as the tensile strength and the breaking elongation, of the punching area 110 decreases relative to the non-punching area 120, so that when the first pole piece 100 is mechanically damaged, the fracture occurs in the punching area 110, and the fracture extends along the first direction.

[0099] In a possible implementation, the tensile strength of the punching area 110 is greater than or equal to 10 MPa and less than or equal to 25 MPa. And / or, the tensile strength of the non-punching area 120 is greater than or equal to 20 MPa and less than or equal to 35 MPa. And / or, the breaking elongation of the punching area 110 is greater than or equal to 1% and less than or equal to 3%. And / or, the breaking elongation of the non-punching area 120 is greater than or equal to 2% and less than or equal to 4.5%.

[0100] In this way, while ensuring that the pole piece meets the strength required for normal use, the tensile strength of the punching area 110 is less than the tensile strength of the non-punching area 120, and the breaking elongation of the punching area 110 is less than the breaking elongation of the non-punching area 120, so that when the first pole piece 100 is mechanically damaged, the fracture occurs in the punching area 110, further ensuring the neatness of the pole piece when it breaks, reducing the short-circuit points generated when the battery composed of the first pole piece 100 is subjected to a heavy impact and breaks, and thus improving the safety of the battery.

[0101] For example, the tensile strength of the punched area 110 can be any one of 10 MPa, 12 MPa, 15 MPa, 20 MPa, 25 MPa or within any two ranges. And / or, the tensile strength of the non-punched area 120 can be any one of 20 MPa, 24 MPa, 28 MPa, 30 MPa, 35 MPa or within any two ranges. And / or, the elongation at break of the punched area 110 can be any one of 1%, 1.2%, 1.5%, 2%, 3% or within any two ranges. And / or, the elongation at break of the non-punched area 120 can be any one of 2%, 2.1%, 2.8%, 3%, 4.5% or within any two ranges.

[0102] The non-punched area 120 can include other areas that are not punched in the straight section, or the non-punched area 120 can also include a circular arc section.

[0103] The performance of the first tab 100 provided by the embodiments of the present application is described below in combination with related tests.

[0104] 1. Weight impact test

[0105] The battery is placed in a normal temperature environment, and the battery is charged at 1C constant current to a voltage of 4.5V, then charged at constant voltage until the current decreases to 0.05C, stop charging, then discharge at 1C constant current to 3.0V, and so on for 5T, and the weight impact test is performed within 24 hours after the last time the battery is fully charged.

[0106] The battery is placed on a flat surface, a steel column with a diameter of 15.8±0.2mm is placed in the center of the battery, the longitudinal axis of the steel column is parallel to the flat surface, a weight with a mass of 9.1±0.1kg is allowed to freely fall from a height of 610±25mm onto the steel column above the center of the battery, and the battery is observed for 6 hours after the test is completed. If the battery does not catch fire or explode, it is recorded as passing.

[0107] 2. Tensile strength test

[0108] The fresh battery is disassembled, and the first tab 100 is taken out. The first tab 100 is cut into a small strip with a width of 24mm along the first direction, the thickness b of the first tab 100 is tested, and the tensile strength and elongation at break are tested using a universal material mechanics testing machine, wherein the gauge length is 50mm and the tensile speed is 50mm / min.

[0109] Table 1 Structure parameter table

[0110]

[0111]

[0112] Table 2 test result table

[0113]

[0114]

[0115] From the above Table 1 and Table 2, it can be seen that the first pole piece 100 of each of Examples 1 to 21 is subjected to the pore-forming treatment, and the structure parameters and arrangement mode of the pore structure 111 meet the requirements, thereby making the first pole piece 100 of each of Examples 1 to 21 have a high pass rate of the weight impact test, and thus the battery of the present embodiment has high safety.

[0116] It can be understood that, in the case where the first interval L2, the second interval W2, and the extension dimension W1 of the pore structure 111 in the second direction are the same, the greater the extension dimension L1 of the pore structure 111 in the first direction, the more conducive to reducing the strength of the first pole piece 100. In the case where the second interval W2, the extension dimension W1 of the pore structure 111 in the second direction, and the extension dimension L1 of the pore structure 111 in the first direction are the same, the greater the first interval L2, the more conducive to reducing the strength of the first pole piece 100. In the case where at least two of the first interval L2, the second interval W2, the extension dimension W1 of the pore structure 111 in the second direction, and the extension dimension L1 of the pore structure 111 in the first direction are not the same, the greater L1 / W1, the more conducive to reducing the strength of the first pole piece 100, the greater W2 / L2, the more conducive to reducing the strength of the first pole piece 100, and the smaller L1 / L2, the more conducive to reducing the strength of the first pole piece 100.

[0117] The Comparative Example 1 is not subjected to the pore-forming treatment, and thus cannot reduce the tensile strength and the elongation at break of the first pole piece 100, thereby resulting in a low pass rate of the weight impact test of the first pole piece 100. In the Comparative Example 2, the extension dimension L1 of the pore structure 111 in the first direction is smaller than the extension dimension W1 of the pore structure 111 in the second direction, and the pore structure 111 is limited in reducing the tensile strength and the elongation at break of the first pole piece 100 in the first direction, thereby resulting in a low pass rate of the weight impact test of the Comparative Example 2. In the Comparative Example 3, the first interval L2 is greater than the second interval W2, and the pore structure 111 is limited in reducing the tensile strength and the elongation at break of the first pole piece 100 in the first direction, and thus the pass rate of the weight impact test of the Comparative Example 3 is low.

[0118] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery, characterized by, The first pole piece comprises a flat section having a perforated area with at least one row of hole structures, one row of the hole structures comprising at least two hole structures arranged in the same direction; The extension size L1 of a single hole structure in the first direction and the extension size W1 of a single hole structure in the second direction satisfy: 1≤L1 / W1<10; In the second direction, the perforated area is centrally arranged on the first pole piece.

2. The battery of claim 1, wherein, The arrangement direction of the hole structures is consistent with the first direction.

3. The battery of claim 1, wherein, The extension size L1 of a single hole structure in the first direction and the extension size W1 of a single hole structure in the second direction further satisfy: 50μm≤W1<L1<2000μm.

4. The battery of claim 2, wherein, In the second direction, the perforated area has at least two rows of hole structures, and the second spacing W2 is provided between adjacent two rows of hole structures, and in the first direction, the first spacing L2 is provided between adjacent two hole structures in the same row of hole structures; The first spacing L2 and the second spacing W2 satisfy: 1≤W2 / L2<500; and / or, the first spacing L2 and the second spacing W2 further satisfy: 10μm≤L2≤W2<5000μm.

5. The battery of claim 4, wherein, The extension size L1 of a single hole structure in the first direction and the first spacing L2 satisfy: 0.2<L1 / L2<10; And / or, the extension size W1 of a single hole structure in the second direction and the second spacing W2 satisfy: 0.5<W2 / W1<100.

6. The battery according to any one of claims 1 to 5, wherein In the first direction, the extension size L3 of the perforated area and the extension size L4 of the first pole piece satisfy: 70%≤L3 / L4≤100%; And / or, in the second direction, the extension size W3 of the perforated area and the extension size W4 of the first pole piece satisfy: 30%≤W3 / W4≤100%.

7. The battery according to any one of claims 1 to 5, wherein The first pole piece further comprises a circular arc section connected to the opposite sides of the flat section in the first direction; In the first direction, the extension size L3 of the perforated area and the extension size L4 of the first pole piece satisfy: 80%≤L3 / L4≤100%; And / or, in the second direction, the extension size W3 of the perforated area and the extension size W4 of the first pole piece satisfy: 30%≤W3 / W4≤100%.

8. The battery according to any one of claims 1 to 5, wherein The area S1 of all the hole structures and the area S2 of the first pole piece satisfy: 0.1%≤S1 / S2≤20%; Wherein, the area S1 of all the hole structures=a(1)+a(2)+…+a(n), n is the number of hole structures.

9. The battery according to any one of claims 1 to 5, wherein The first pole piece comprises a first current collector and a first active material layer, the first active material layer is arranged on at least one side of the first current collector, and the hole structure is arranged on at least one of the first active material layer and the first current collector.

10. The battery of claim 9, wherein, The hole structure is arranged on the first active material layer, and the extension size H1 of the hole structure in the third direction and the extension size H2 of the first active material layer in the third direction satisfy: 0.3≤H1 / H2≤1; Alternatively, the hole structure is arranged on the first current collector, and an extension size H1 of the hole structure along a third direction satisfies 0.5≤H1 / H3≤1, where H3 is an extension size of the first current collector along the third direction. Alternatively, the hole structure penetrates through opposite surfaces of the first pole piece.

11. The battery of any one of claims 1-5, wherein, The shape of the hole structure includes at least one of a circle, an ellipse, a diamond, and a rectangle.

12. The battery of any one of claims 1-5, wherein, The first pole piece further includes a non-punching area, and a ratio of the tensile strength of the punching area to the tensile strength of the non-punching area is greater than or equal to 50% and less than or equal to 96%. And / or, a ratio of the breaking elongation of the punching area to the breaking elongation of the non-punching area is greater than or equal to 50% and less than or equal to 98%.

13. The battery of claim 12, wherein, The tensile strength of the punching area is greater than or equal to 10 MPa and less than or equal to 25 MPa. And / or, the tensile strength of the non-punching area is greater than or equal to 20 MPa and less than or equal to 35 MPa. And / or, the breaking elongation of the punching area is greater than or equal to 1% and less than or equal to 3%; and / or, the breaking elongation of the punching area is greater than or equal to 2% and less than or equal to 4.5%.

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