Battery

Abstract

The present application provides a battery, the battery includes a first pole piece, when the two sides of the first pole piece along the first direction are subjected to a tensile force along the first direction, the first pole piece breaks into a first sheet and a second sheet, the first sheet and the second sheet have a fracture on one side close to each other, the fracture extends along the second direction, the uniformity of the fracture S = 1-h / f, and the uniformity S satisfies: S>80%; wherein f is the extension length of the first pole piece for testing along the second direction, h is the distance between the peak of the fracture and the trough of the fracture, and the first direction is perpendicular to the second direction. When the battery of the present application is subjected to a heavy object impact test, the short-circuit points generated when the first pole piece breaks are fewer, and the battery safety is higher.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery. Background Art

[0002] When a lithium-ion battery is exposed to foreign matter, its temperature can easily rise sharply in a short period of time, eventually causing combustion and explosion.

[0003] When a lithium-ion battery short-circuits, four types of contacts may occur: contact between the positive active material and the negative active material, contact between the positive active material and the negative current collector, contact between the positive current collector and the negative active material, and contact between the positive current collector and the negative current collector. Among them, the contact between the positive current collector and the negative active material is the most dangerous, which will cause the battery to burn violently in a short period of time. Therefore, how to reduce the probability of short circuits in lithium-ion batteries when they are mechanically damaged is an urgent problem to be solved. Summary of the invention

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

[0005] The battery provided by the present application comprises a first pole piece, and when both sides of the first pole piece along a first direction are subjected to a tensile force along the first direction, the first pole piece is broken into a first sheet body and a second sheet body, and a side where the first sheet body and the second sheet body are close to each other has a fracture, and the fracture extends along a second direction, and the uniformity S of the fracture is S=1-h / f, and the uniformity S satisfies: S>80%;

[0006] Wherein, f is the extension length of the first pole piece used for testing along the second direction, h is the distance between the crest of the fracture and the trough of the fracture, and the first direction is perpendicular to the second direction.

[0007] In a possible implementation, a distance h between a wave crest of the fracture and a wave trough of the fracture satisfies: 0≤h≤5mm.

[0008] In a possible implementation, the first pole piece includes a straight section, the straight section has a perforated area, the perforated area has at least two hole structures, the at least two hole structures are arranged along the second direction, and the fracture passes through at least one hole structure;

[0009] And / or, the straight section has a notch, the notch extends along the second direction, and the fracture surface at least partially overlaps with the notch.

[0010] In a possible implementation, an extension dimension L1 of a single hole structure along the second direction and an extension dimension W1 of the hole structure along the first direction satisfy: 1≤L1 / W1<10;

[0011] And / or, an extension dimension L1 of the hole structure along the second direction and an extension dimension W1 of the hole structure along the first direction satisfy: 50 μm<W1≤L1<2000 μm.

[0012] In a possible implementation manner, the distance h between the wave crest of the fracture and the wave trough of the fracture and the extension dimension W1 of the hole structure along the first direction satisfy: h≤W1.

[0013] In a possible implementation, in the second direction, in the same row of hole structures, there is a first spacing L2 between two adjacent hole structures, and the first spacing L2 and the second spacing W2 satisfy: 1≤W2 / L2<500;

[0014] And / or, in the first direction, the perforated area has at least two rows of hole structures, and there is a second spacing W2 between two adjacent rows of hole structures, and the first spacing L2 and the second spacing W2 satisfy: 10 μm<L2≤W2<5000 μm.

[0015] In a possible implementation, the extension dimension L1 of the hole structure along the second direction and the first spacing L2 satisfy: 0.2<L1 / L2<10;

[0016] And / or, an extension dimension W1 of the hole structure along the first direction and the second interval W2 satisfy: 0.5<W2 / W1<100.

[0017] In a possible implementation, in the first direction, an extension dimension W3 of the perforated area and an extension dimension W4 of the first pole piece satisfy: 30%≤W3 / W4≤100%.

[0018] In a possible implementation, the first pole piece further includes an arc segment, and the arc segment is connected to two opposite sides of the straight segment along the second direction;

[0019] In the first direction, an extension dimension W3 of the perforated area and an extension dimension W4 of the first pole piece satisfy: 30%≤W3 / W4≤100%.

[0020] In a possible implementation, in the first direction, the perforated area is centrally disposed on the first pole piece.

[0021] In a possible implementation, the area S1 of all hole structures and the area S2 of the first pole piece satisfy: 0.1%≤S1 / S2≤20%;

[0022] Among them, the area of ​​all hole structures S1=a(1)+a(2)+…+a(n), where n is the number of hole structures.

[0023] In a possible implementation, the first pole piece includes a first current collector and a first active material layer, the first active material layer is disposed on at least one side of the first current collector, and the hole structure is disposed in at least one of the first active material layer and the first current collector;

[0024] And / or, the notch is provided in at least one of the first active material layer and the first current collector.

[0025] In a possible implementation, the pore structure is provided in the first active material layer, and an extension dimension H1 of the pore structure along the third direction and an extension dimension H2 of the first active material layer along the third direction satisfy: 0.3≤H1 / H2≤1;

[0026] Alternatively, the hole structure is provided in the first current collector, and an extension dimension H1 of the hole structure along the third direction and an extension dimension H3 of the first current collector along the third direction satisfy: 0.5≤H1 / H3≤1;

[0027] Alternatively, the hole structure penetrates two opposite sides of the first pole piece.

[0028] In a possible implementation manner, the shape of the hole structure includes at least one of a circle, an ellipse, a diamond, and a rectangle.

[0029] In a possible implementation, the first pole piece further includes a non-perforated area, and the ratio of the tensile strength of the perforated area to the tensile strength of the non-perforated area is greater than or equal to 50% and less than or equal to 96%;

[0030] And / or, the ratio of the elongation at break of the perforated area to the elongation at break of the non-perforated area is greater than or equal to 50% and less than or equal to 98%.

[0031] 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;

[0032] and / or, the tensile strength of the non-perforated area is greater than or equal to 20 MPa and less than or equal to 35 MPa;

[0033] and / or, the elongation at break of the perforated area is greater than or equal to 1% and less than or equal to 3%;

[0034] And / or, the elongation at break of the perforated area is greater than or equal to 2% and less than or equal to 4.5%.

[0035] The battery of the embodiment of the present application includes a first pole piece, the first pole piece is broken into a first sheet and a second sheet when subjected to a tensile force along a first direction, the first sheet and the second sheet both have a fracture, the fracture extends along a second direction, the distance between the crest of the fracture and the trough of the fracture in the first direction is h, the extension length of the first pole piece used for testing along the second direction is f, the uniformity of the fracture S=1-h / f, and the uniformity S is greater than 80%. In this way, when the battery provided by the embodiment of the present application is subjected to a heavy object impact test, fewer short-circuit points are generated when the first pole piece is broken, thereby improving the safety of the battery.

[0036] In addition to the technical problems solved by the embodiments of the present application described above, the technical features that constitute the technical solutions, and the beneficial effects brought about by the technical features of these technical solutions, other technical problems that can be solved by the battery provided by the present application, other technical features included in the technical solutions, and the beneficial effects brought about by these technical features will be further described in detail in the specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0038] Figure 1 A schematic diagram of the structure of a battery provided in an embodiment of the present application;

[0039] Figure 2 A schematic diagram of the structure of a battery provided in an embodiment of the present application when the first pole piece is broken;

[0040] Figure 3 for Figure 2 A schematic diagram of the structure of the first sheet;

[0041] Figure 4 Another schematic diagram of the structure of the first sheet in the battery provided in an embodiment of the present application;

[0042] Figure 5 A schematic diagram of the structure of the first pole piece in the battery provided in an embodiment of the present application;

[0043] Figure 6 Another structural schematic diagram of the first pole piece in the battery provided in the embodiment of the present application;

[0044] Figure 7 This is another schematic structural diagram of the first electrode in the battery provided in an embodiment of the present application.

[0045] Description of reference numerals:

[0046] 100 - first pole piece; 100a - first sheet body; 100b - second sheet body; 110 - perforated area; 111 - hole structure; 120 - non-perforated area; 130 - first current collector; 140 - first active material layer; 200 - first pole ear; X - first direction; Y - second direction; Z - third direction. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme in the embodiment of the present application will be described in more detail below in conjunction with the drawings in the preferred embodiments of the present application. In the drawings, the same or similar reference numerals throughout represent the same or similar parts or parts with the same or similar functions. The described embodiments are part of the embodiments of the present application, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application. The embodiments of the present application are described in detail below in conjunction with the drawings.

[0048] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, or it can be an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0049] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are orientations or positional relationships 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 referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0050] The terms "first", "second", "third" (if any) in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the application described herein can be implemented in an order other than those illustrated or described herein, for example.

[0051] In addition, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, for example, a process, method, system, product, or display comprising a series of steps or elements is not necessarily limited to those steps or elements explicitly listed, but may include other steps or elements not explicitly listed or inherent to such process, method, product, or display.

[0052] When a lithium-ion battery short-circuits, four types of contacts may occur: contact between the positive active material and the negative active material, contact between the positive active material and the negative current collector, contact between the positive current collector and the negative active material, and contact between the positive current collector and the negative current collector. Among them, the contact between the positive current collector and the negative active material is the most dangerous, which will cause the battery to burn violently in a short period of time. Therefore, how to reduce the probability of short circuits in lithium-ion batteries when they are mechanically damaged is an urgent problem to be solved.

[0053] In view of this, an embodiment of the present application provides a battery, in which the first pole piece will break into a first sheet and a second sheet after being subjected to a pulling force along a first direction, and the side of the first sheet facing the second sheet and the side of the second sheet facing the first sheet both have a fracture, and the uniformity of the fracture is greater than 90%. The uniformity of the fracture is relatively high. In this way, when the battery is subjected to a heavy object impact test, fewer short-circuit points are generated when the first pole piece breaks, thereby improving the safety of the battery.

[0054] The specific implementation of the battery provided in this embodiment is described in detail below with reference to the accompanying drawings.

[0055] Reference Figures 1 to 4 As shown, the battery provided in the present application includes a first pole piece 100. When both sides of the first pole piece 100 along the first direction X are subjected to a tensile force along the first direction X, the first pole piece 100 breaks into a first sheet 100a and a second sheet 100b. A side where the first sheet 100a and the second sheet 100b are close to each other has a fracture, and the fracture extends along the second direction Y. The uniformity S of the fracture is 1-h / f, and the uniformity S satisfies: S>80%.

[0056] Wherein, f is the extension length of the first pole piece 100 for testing along the second direction Y, h is the distance between the wave crest of the fracture and the wave trough of the fracture, and the first direction X is perpendicular to the second direction Y.

[0057] It can be understood that the battery may further include a second electrode plate and a diaphragm, and one of the first electrode plate 100 and the second electrode plate is a positive electrode plate, and the other is a negative electrode plate. For example, the first electrode plate 100 is a negative electrode and the second electrode plate is a positive electrode, or the first electrode plate 100 is a positive electrode and the second electrode plate is a negative electrode.

[0058] The first pole piece 100, the diaphragm and the second pole piece are stacked in sequence and then wound to form a wound battery cell. Alternatively, the first pole piece 100, the diaphragm and the second pole piece are stacked in sequence to form a stacked battery cell. After that, a fresh battery can be formed through steps such as shelling, liquid injection and formation.

[0059] Disassemble the fresh battery and take out the first pole piece 100. For a laminated cell, the length of the first pole piece 100 is relatively short, and the entire first pole piece 100 can be selected for the uniformity test. For a wound cell, the length of the first pole piece 100 is relatively long, and a part of the first pole piece 100 can be selected for the uniformity test. For example, the first pole piece 100 is evenly cut into five parts along its length direction, and any one of them is selected for the uniformity test.

[0060] Then, a tensile force is applied to both sides of the first pole piece 100 along the first direction X using a tensile testing machine. After the first pole piece 100 is pulled apart into the first sheet 100a and the second sheet 100b, the first sheet 100a has a break toward the second sheet 100b, and the second sheet 100b has a break toward the first sheet 100a. After the break of the first sheet 100a and the break of the second sheet 100b are assembled together, the first sheet 100a and the second sheet 100b can together constitute the first pole piece 100. During testing, the uniformity S of the break of the first sheet 100a can be tested, and the uniformity S of the break of the second sheet 100b can also be tested.

[0061] The uniformity of the fracture S=1-h / f. Thus, the uniformity S can be obtained by measuring the extension dimension f of the first pole piece 100 along the second direction Y and the distance h between the wave crest and the wave trough of the fracture.

[0062] It can be seen from the above formula that when the first pole piece 100 is subjected to multiple regularity tests, and the extension dimension f of the first pole piece 100 along the second direction Y is the same in multiple tests, if the distance h between the wave crest of the fracture and the wave trough of the fracture is larger, the regularity S is smaller, which indicates that the unevenness of the fracture is higher and the fracture is more irregular. If the distance h between the wave crest of the fracture and the wave trough of the fracture is smaller, the regularity S is larger, which indicates that the unevenness of the fracture is lower and the fracture is more regular.

[0063] The first pole piece 100 is subjected to multiple regularity tests. When the extension dimensions f of the first pole piece 100 along the second direction Y are different in the multiple tests, if the distance h between the wave crest of the fracture and the wave trough of the fracture is the same, the smaller the extension dimension f of the first pole piece 100 along the second direction Y, the smaller the regularity S, indicating that the unevenness of the fracture is higher and the fracture is more irregular. If the distance h between the wave crest of the fracture and the wave trough of the fracture is the same, the larger the extension dimension f of the first pole piece 100 along the second direction Y, the larger the regularity S, indicating that the unevenness of the fracture is lower and the fracture is more regular.

[0064] In this way, the uniformity S of the fracture can be reasonably and accurately evaluated according to the extension dimension f of the first pole piece 100 along the second direction Y and the distance h between the wave crest of the fracture and the wave trough of the fracture.

[0065] When the first pole piece 100 of the embodiment of the present application is subjected to a uniformity test, the first pole piece 100 will be broken into a first sheet 100a and a second sheet 100b along a first direction X, and the uniformity S of the first pole piece 100 is greater than 80%. In this way, when a battery having the first pole piece 100 is subjected to a heavy object impact test, the first pole piece 100 has fewer short-circuit points when it is broken, which can help the battery improve the pass rate of the heavy object impact test, and the battery is safer when in use.

[0066] It should be noted that the extension dimension f of the first pole piece 100 used for testing along the second direction Y should be understood as the extension length of the first pole piece 100 for uniformity testing along the second direction Y, rather than the extension length of the first pole piece 100 directly disassembled along the second direction Y.

[0067] That is to say, if the first pole piece 100 is cut before the uniformity test, the extension dimension f of the first pole piece 100 along the second direction Y is the extension length of the first pole piece 100 used for the uniformity test along the second direction Y after the first pole piece 100 is disassembled and cut. If the uniformity test is performed without cutting the first pole piece 100, the extension dimension f of the first pole piece 100 used for the test along the second direction Y is the extension length of the disassembled first pole piece 100 along the second direction Y.

[0068] The battery of the embodiment of the present application includes a first pole piece 100, the first pole piece 100 is broken into a first sheet 100a and a second sheet 100b when subjected to a tensile force along a first direction X, the first sheet 100a and the second sheet 100b both have a fracture, the fracture extends along a second direction Y, the distance between the crest of the fracture and the trough of the fracture in the first direction X is h, the extension length of the first pole piece 100 used for testing along the second direction Y is f, the uniformity of the fracture S=1-h / f, and the uniformity S is greater than 80%. In this way, when the battery provided by the embodiment of the present application is subjected to a heavy object impact test, fewer short-circuit points are generated when the first pole piece 100 is broken, thereby improving the safety of the battery.

[0069] In a possible implementation, the extension dimension f of the first pole piece 100 for testing along the second direction Y satisfies: 10 mm ≤ f ≤ 150 mm. And / or the distance h between the wave crest of the fracture and the wave trough of the fracture satisfies: 0 ≤ h ≤ 5 mm.

[0070] That is to say, before the uniformity test is performed, the first pole piece 100 is sampled, and the extension dimension f of the sampled first pole piece 100 along the second direction Y may be between 10 mm and 150 mm, thereby facilitating the test and setting a reasonable evaluation interval.

[0071] It can be understood that when sampling the first pole piece 100, if the sampling length is too large, it is convenient for testing, but it will also increase the deviation between the uniformity S obtained by the test and the actual situation. If the sampling length is too small, the uniformity S obtained by the final test will deviate greatly from the actual situation, which will increase the error of the uniformity test. Therefore, the sampling length can be selected moderately, and f can be set between 10mm and 150mm.

[0072] After the uniformity test, the fracture can be enlarged to facilitate viewing of the peaks and troughs of the fracture, and measuring the spacing h between the peaks and troughs of the fracture in the first direction X. The first pole piece 100 of this embodiment is subjected to a uniformity test, and the spacing h between the peaks and troughs of the fracture in the first direction X is between 0.1 mm and 5 mm. In this way, the uniformity S of the fracture can be greater than 80%, which is beneficial in helping the battery pass the heavy object impact test.

[0073] For example, the extension dimension f of the first pole piece 100 for testing along the second direction Y can be any one of 10 mm, 24 mm, 50 mm, 100 mm, and 150 mm, or can be within any two numerical ranges, so as to facilitate sampling of first pole pieces 100 of batteries of different specifications. And / or, the distance h between the peak of the fracture and the trough of the fracture can be any one of 0.1 mm, 0.5 mm, 1 mm, 2 mm, and 5 mm, or can be within any two numerical ranges.

[0074] Reference Figure 1 , Figure 5 and Figure 6 As shown, in some embodiments, the first pole piece 100 includes a straight section, the straight section has a perforated area 110, the perforated area 110 has at least two hole structures 111, the at least two hole structures 111 are arranged along the second direction Y, and the fracture passes through at least one hole structure 111.

[0075] And / or, in some embodiments, the first pole piece 100 includes a straight section, the straight section has a notch, the notch extends along the second direction Y, and the fracture overlaps at least partially with the notch. In this embodiment, the straight section of the first pole piece 100 can be punched to form a punching area 110 in the straight section, and a plurality of hole structures 111 of the punching area 110 are arranged in a line along the second direction Y, or the straight section of the first pole piece 100 can be thinned to form a linear notch in the straight section.

[0076] Both of the above methods can reduce the mechanical strength of the first pole piece 100. In this way, when the first pole piece 100 is tested for uniformity, the fracture will extend along the second direction Y, the fracture will pass through at least one hole structure 111 or the fracture will at least partially overlap with the notch, and the uniformity S of the fracture is greater than 80%. When the battery made of the first pole piece 100 is subjected to a heavy object impact test, the pass rate of the test is higher.

[0077] It should be understood that, for a laminated battery cell, the first pole sheet 100 may include a straight section. For a wound battery cell, the first pole sheet 100 may include a straight section and may also include an arc section.

[0078] Regardless of the form of the battery cell, a punching area 110 or a notch can be set on the straight section of the first pole piece 100. In this way, since the hole structure 111 or the notch is set on the straight section, its mechanical strength can be reduced. When the first pole piece 100 is tested for uniformity, the first pole piece 100 will break along the arrangement direction of the hole structure 111 or the extension direction of the notch to form a fracture, and the fracture has a high degree of uniformity.

[0079] The arc segment of the first pole piece 100 may not be provided with the hole structure 111, thereby avoiding affecting the mechanical strength of the arc segment. When sampling the first pole piece 100 of the wound battery cell for a uniformity test, a straight segment with the hole structure 111 may be selected for testing.

[0080] Reference Figure 1 As shown, in some embodiments, the extension dimension L1 of the hole structure 111 along the second direction Y and the extension dimension W1 of the hole structure 111 along the first direction X satisfy: 1≤L1 / W1<10.

[0081] And / or, the extension dimension L1 of the hole structure 111 along the second direction Y and the extension dimension W1 of the hole structure 111 along the first direction X satisfy: 50μm<W1≤L1<2000μm. That is, in the second direction Y, the extension dimension L1 of the hole structure 111 can be larger, and in the first direction X, the extension dimension W1 of the hole structure 111 can be smaller, L1 and W1 satisfy: 1<L1 / W1<10, and / or, L1 and W1 satisfy: 50μm<W1<L1<2000μm.

[0082] In this way, the hole structure 111 can be made to be slender, so that when the first pole piece 100 is subjected to a tensile force along the first direction X, because the multiple hole structures 111 are arranged along the second direction Y, when the first pole piece 100 is tested for uniformity, the hole structure 111 arranged along the second direction Y reduces the strength of the first pole piece 100, and the first pole piece 100 is more easily damaged along the arrangement direction of the hole structure 111, so that after the first pole piece 100 is broken, a fracture extending along the second direction Y is formed, and the fracture will pass through the multiple hole structures 111 arranged along the second direction Y in sequence, so that the fracture is more uniform, thereby reducing the short-circuit points of the battery during the heavy object impact test, thereby improving the safety of the battery.

[0083] Alternatively, the extension dimension L1 of the hole structure 111 may also be equal to the extension dimension W1 of the hole structure 111 . When arranged, the strength of the first pole piece 100 in the second direction Y may be effectively reduced by reasonably setting the spacing between adjacent hole structures 111 .

[0084] For example, the ratio of the extension dimension L1 of the hole structure 111 along the second direction Y to the extension dimension W1 of the hole structure 111 along the first direction X may be any one of 1.5, 3, 5, 8, and 9, or be within any two numerical ranges. And / or, the extension dimension W1 of the hole structure 111 along the first direction X may be any one of 55 μm, 100 μm, 1000 μm, 1500 μm, and 1500 μm, or be within any two numerical ranges, and the extension dimension L1 of the hole structure 111 along the second direction Y may be any one of 60 μm, 200 μm, 1200 μm, 1600 μm, and 1900 μm, or be within any two numerical ranges.

[0085] It should be noted that, for hole structures 111 of different shapes, for example, when the hole structure 111 is circular, the extension dimension L1 of the hole structure 111 along the second direction Y and the extension dimension W1 of the hole structure 111 along the first direction X can both be understood as the diameter of the circle. Alternatively, when the hole structure 111 is elliptical, the extension dimension L1 of the hole structure 111 along the second direction Y can be understood as the length of the major axis of the ellipse, and the extension dimension W1 of the hole structure 111 along the first direction X can be understood as the length of the minor axis of the ellipse. Alternatively, when the hole structure 111 is rhombus-shaped, the extension dimension L1 of the hole structure 111 along the second direction Y can be understood as the diagonal length of the rhombus in this direction, and the extension dimension W1 of the hole structure 111 along the first direction X can be understood as the diagonal length of the rhombus in this direction. Alternatively, when the hole structure 111 is an irregular trapezoid, the extension dimension L1 of the hole structure 111 along the second direction Y can be understood as the maximum dimension of the irregular trapezoid in this direction, and the extension dimension W1 of the hole structure 111 along the first direction X can be understood as the maximum dimension of the irregular trapezoid in this direction. Figure 1 , Figure 3 and Figure 4 As shown, in a possible implementation, the distance h between the wave crest of the fracture and the wave trough of the fracture and the extension dimension W1 of the hole structure 111 along the first direction X satisfy: h≤W1.

[0086] It can be understood that, since the first pole piece 100 of the present embodiment is provided with a perforated area 110 and at least one row of hole structures 111 arranged along the second direction Y is provided in the perforated area 110, when the first pole piece 100 is subjected to a uniformity test, the fracture edge passes through each hole structure 111 of the same row of hole structures 111 in sequence, thereby making the distance h between the crest and the trough of the fracture less than or equal to the extension dimension W1 of the hole structure 111 along the first direction X.

[0087] Reference Figure 1 As shown, in a possible implementation, in the second direction Y, in the same row of hole structures 111, there is a first spacing L2 between two adjacent hole structures 111, and in the first direction X, the perforated area 110 has at least two rows of hole structures 111, and there is a second spacing W2 between two adjacent rows of hole structures 111.

[0088] The first interval L2 and the second interval W2 satisfy: 1≤W2 / L2<500, and / or the first interval L2 and the second interval W2 satisfy: 10 μm<L2≤W2<5000 μm.

[0089] That is, when the hole structures 111 are arranged along the second direction Y, and multiple rows of hole structures 111 are arranged in the first direction X, there is a second spacing W2 between two adjacent rows of hole structures 111 in the first direction X, and there is a first spacing L2 between two adjacent hole structures 111 in the second direction Y, and the first spacing L2 is less than or equal to the second spacing W2. In addition, the first spacing L2 is less than 50 times the second spacing W2, which is conducive to setting a suitable number of hole structures 111 in the perforated area 110.

[0090] Thus, relatively speaking, in the first direction X, the distance between adjacent hole structures 111 is larger, the hole structures 111 are arranged more sparsely, and the first pole piece 100 can withstand greater stress in this direction. In the second direction Y, the distance between adjacent hole structures 111 is smaller, the hole structures 111 are arranged more densely, and the first pole piece 100 can withstand less stress in this direction, thereby making it easier for the first pole piece 100 to break and form a fracture extending along the second direction Y when the first pole piece 100 is tested for uniformity, and making the uniformity S of the fracture greater than 80%, which is conducive to improving the pass rate of the heavy object impact test of the battery.

[0091] It should be noted that the first spacing L2 can be the center spacing between two adjacent hole structures 111 in the second direction Y, that is, from 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 that are close to each other in the second direction Y.

[0092] In specific configuration, the first spacing L2 and the second spacing W2 may be set between 50 μm and 2000 μm, thereby taking both processability and the density of the hole structure 111 into consideration, thereby effectively reducing the mechanical strength of the first pole piece 100 in the second direction Y.

[0093] For example, the ratio W2 / L2 of the second spacing W2 to the first spacing L2 may be any one of 5, 5, 100, 300, 400 or any two numerical ranges. And / or, the first spacing L2 may be any one of 10 μm, 100 μm, 1000 μm, 2000 μm, 3000 μm or any two numerical ranges. The second spacing W2 may be any one of 20 μm, 200 μm, 600 μm, 2000 μm, 5000 μm or any two numerical ranges.

[0094] It should be understood that in the first direction X, the multiple rows of hole structures 111 can be arranged at uniform intervals or uneven intervals, and in the second direction Y, the multiple hole structures 111 can be arranged at uniform intervals or uneven intervals, which is not limited in the embodiments of the present application.

[0095] Reference Figure 1 As shown, in a possible implementation, the extension dimension L1 of the hole structure 111 along the second direction Y and the first spacing L2 satisfy: 0.2<L1 / L2<10. And / or, the extension dimension W1 of the hole structure 111 along the first direction X and the second spacing W2 satisfy: 0.5<W2 / W1<100.

[0096] In this way, the mechanical strength of the first pole piece 100 in the second direction Y can be lower than the mechanical strength of the first pole piece 100 in the first direction X, and the first pole piece 100 can be subjected to smaller stress in the second direction Y, so that the first pole piece 100 breaks to form a fracture extending along the second direction Y, and the uniformity S of the fracture is greater than 80%, thereby improving the safety of the battery.

[0097] For example, the ratio L1 / L2 of the extension dimension L1 of the hole structure 111 along the second direction Y to the first spacing L2 may be any one of 0.25, 0.4, 2, 5, and 9, or may be within any two numerical ranges. And / or, the ratio W2 / W1 of the second spacing W2 to the extension dimension W1 of the hole structure 111 along the first direction X may be any one of 0.6, 0.8, 5, 10, and 80, or may be within any two numerical ranges.

[0098] Reference Figure 1 As shown, in a possible implementation, in the first direction X, the extension dimension W3 of the perforated area 110 and the extension dimension W4 of the first pole piece 100 satisfy: 30%≤W3 / W4≤100%.

[0099] And / or, in the second direction Y, an extension dimension L3 of the perforated area 110 and an extension dimension f of the first pole piece 100 satisfy: 70%≤L3 / f≤100%.

[0100] That is, in the first direction X, some or all straight segments are provided with perforated areas 110, i.e. 30%≤W3 / W4≤100%. And / or, in the second direction Y, some or all straight segments are provided with perforated areas 110, i.e. 70%≤L3 / f≤100%.

[0101] In this way, the strength of the first pole piece 100 in the second direction Y can be lower than that in the first direction X, so that the first pole piece 100 can be broken more neatly along the second direction Y. In addition, it can also ensure that the steel rod used for the test can completely fall into the punching area 110 when the battery is subjected to a heavy object impact test.

[0102] Exemplarily, the ratio W3 / W4 of the extension dimension W3 of the perforated area 110 to the extension dimension W4 of the first pole piece 100 may be any one of 30%, 50%, 60%, 80%, 100% or within any two numerical ranges. And / or, the ratio L3 / f of the extension dimension L3 of the perforated area 110 to the extension dimension f of the first pole piece 100 may be any one of 70%, 75%, 80%, 90%, 100% or within any two numerical ranges.

[0103] It should be noted that, since the steel rod needs to fall on the center of the first pole piece 100 when conducting a heavy object impact test, and the length direction of the steel rod is along the second direction Y, in some embodiments, the punching area 110 can be centered in the first direction X, so that the distance between the punching area 110 and the two side edges of the first pole piece 100 along the first direction X is basically equal, thereby ensuring that the steel rod falls within the punching area 110.

[0104] It should be noted that, on both sides of the first pole piece 100 along the first direction X, that is, on both sides of the width direction of the first pole piece 100, setting the perforated area 110 on one side or both sides of the first pole piece 100 along the first direction X is likely to cause powder falling off the edge of the first pole piece 100, and when the first pole piece 100 is a negative electrode sheet, setting the hole structure 111 on the edge of the first pole piece 100 will reduce the lithium ion embedding sites at the edge of the first pole piece 100, which is likely to cause lithium deposition in the battery.

[0105] Exemplarily, the first pole piece 100 is evenly divided into N equal parts along the first direction X. When N is an odd number, the perforation area 110 is located in the (N+1) / 2th part. When N is an even number, the perforation area 110 is located in the N / 2th part or the (N+1) / 2th part. Alternatively, the perforation area 110 is located in both the N / 2th part and the (N+1) / 2th part.

[0106] Reference Figure 1 , Figure 3 and Figure 4 As shown, in a possible implementation, the first pole piece 100 further includes an arc segment, which is connected to opposite sides of the straight segment along the second direction Y. In the first direction X, the extension dimension W3 of the perforated area 110 and the extension dimension W4 of the first pole piece 100 satisfy: 30%≤W3 / W4≤100%. And / or, in the second direction Y, the extension dimension L3 of the perforated area 110 and the extension dimension f of the first pole piece 100 satisfy: 80%≤L3 / f≤100%.

[0107] That is to say, in the wound cell, the first pole piece 100 has a straight section and an arc section, the straight section is provided with a perforated area 110, and the arc section may not be provided with a perforated area 110, thereby avoiding reducing the mechanical properties of the arc section. Therefore, in the first direction X, the extension dimension W3 of the perforated area 110 and the extension dimension W4 of the first pole piece 100 satisfy: 30% ≤ W3 / W4 ≤ 100%, and in the second direction Y, the extension dimension L3 of the perforated area 110 and the extension dimension f of the first pole piece 100 satisfy: 80% ≤ L3 / f ≤ 100%, thereby ensuring that the straight section of the first pole piece 100 is provided with sufficient hole structures 111.

[0108] Among them, the perforated area 110 described in this embodiment can be understood as an area enclosed by multiple hole structures 111. The perforated area 110 is provided with a hole structure 111. In the second direction Y, the hole structure 111 needs to be dense enough to form a fracture extending along the second direction Y when the first pole piece 100 is subjected to a uniformity test.

[0109] For example, refer to Figure 1 As shown, the first pole piece 100 has a perforated area 110 , and the perforated area 110 is provided with four rows of hole structures 111 along the first direction X. In the second direction Y, each row of hole structures 111 has 5 hole structures 111 . In this way, the perforated area 110 can be understood as the area enclosed by these four rows of hole structures 111 .

[0110] In a battery with a center-pole lug, since the first pole sheet 100 needs to reserve some empty foil area for processing into the first pole lug 200, the hole structure 111 may not be set on the side of the first pole sheet 100 close to the first pole lug 200, and the hole structure 111 may be set in the middle of the first pole sheet 100 and on the side of the first pole sheet 100 away from the first pole lug 200, thereby avoiding reducing the connection strength of the first pole lug 200.

[0111] In a possible implementation, the area S1 of all hole structures 111 in the perforated area 110 and the area S2 of the first pole piece 100 satisfy: 0.1%≤S1 / S2≤20%. Wherein, the area S1 of the hole structure 111 = a(1)+a(2)+…+a(n), where n is the number of hole structures 111.

[0112] Such a configuration can effectively ensure the density of the hole structure 111 of the perforated area 110, so that the hole structure 111 can effectively reduce the mechanical strength of the first pole piece 100 to a preset range, thereby improving the uniformity S of the first pole piece 100 and reducing the capacity loss of the battery.

[0113] In one possible implementation, the first pole piece 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, the hole structure 111 is arranged on at least one of the first active material layer 140 and the first current collector 130, and / or the notch is arranged on at least one of the first active material layer 140 and the first current collector 130.

[0114] It can be understood that the hole structure 111 and / or the notch can be provided in the first active material layer 140, or the hole structure 111 and / or the notch can be provided in the first current collector 130, or the hole structure 111 and / or the notch can be provided in both the first active material layer 140 and the first current collector 130. Regardless of whether the hole structure 111 and / or the notch are provided in the first current collector 130 or the first active material layer 140, or the hole structure 111 runs through the first active material layer 140 and the first current collector 130, the elongated hole structure 111 and the notch densely arranged along the second direction Y can effectively reduce the mechanical strength of the first pole piece 100 along the second direction Y.

[0115] Furthermore, by providing the hole structure 111 in the first pole piece 100 , the degree of infiltration of the electrolyte into the first pole piece 100 can be improved, thereby reducing dark spots or lithium precipitation caused by poor infiltration of active materials, thereby improving the cycle performance of the battery.

[0116] Reference Figure 7 As shown, in some embodiments, the hole structure 111 is disposed in the first active material layer 140, and the extension dimension H1 of the hole structure 111 along the third direction Z and the extension dimension H2 of the first active material layer 140 along the third direction Z satisfy: 0.3≤H1 / H2≤1. In this way, it can be ensured that the hole structure 111 disposed in the first active material layer 140 has a certain depth, thereby effectively reducing the mechanical strength of the first electrode 100, so that the uniformity S is greater than 80%.

[0117] Alternatively, in some embodiments, the hole structure 111 is disposed in the first current collector 130, and the extension dimension H1 of the hole structure 111 along the third direction Z and the extension dimension H3 of the first current collector 130 along the third direction Z satisfy: 0.5≤H1 / H3≤1. In this way, it can be ensured that the hole structure 111 disposed in the first current collector 130 has a certain depth, thereby effectively reducing the mechanical strength of the first pole piece 100, so that the uniformity S is greater than 80%. Among them, Figure 7 The case where H1 / H3 = 1 is shown, that is, the hole structure 111 penetrates two opposite surfaces of the first current collector 130 .

[0118] Alternatively, in some embodiments, the hole structure 111 passes through two opposite sides of the first pole piece 100 .

[0119] For example, the ratio H1 / H2 of the extension dimension H1 of the pore structure 111 along the third direction Z to the extension dimension H2 of the first active material layer 140 along the third direction Z may be any one of 0.3, 0.4, 0.5, 0.9, and 1, or any two numerical ranges. Alternatively, the ratio H1 / H3 of the extension dimension H1 of the pore structure 111 along the third direction Z to the extension dimension H3 of the first current collector 130 along the third direction Z may be any one of 0.5, 0.7, 0.8, 0.9, and 1, or any two numerical ranges.

[0120] In a possible implementation manner, the shape of the hole structure 111 includes at least one of an ellipse, a diamond, and a rectangle.

[0121] In this way, when the shape of the hole structure 111 includes one or more of an ellipse, a rhombus and a rectangle, the extension dimension L1 of the hole structure 111 along the second direction Y can be made greater than the extension dimension W1 of the hole structure 111 along the first direction X, so that the hole structure 111 is slender in the second direction Y, so that when the first pole piece 100 is subjected to a uniformity test, the first pole piece 100 is broken along the second direction Y, and the uniformity S after breaking is greater than 80%.

[0122] When the shape of the hole structure 111 is circular, the extension dimension L1 of the hole structure 111 along the second direction Y is equal to the extension dimension W1 of the hole structure 111 along the first direction X.

[0123] It should be understood that in a single-row hole structure 111, the shape of each hole structure 111 can be the same or different, and in a multi-row hole structure 111, the shape of each row of hole structures 111 can be the same or different. For example, for two adjacent rows of hole structures 111, the shape of one row of hole structures 111 includes an ellipse, and the shape of the other row of hole structures 111 includes an ellipse, a diamond, and a rectangle.

[0124] In a possible implementation, the first pole piece 100 further includes a non-perforated area 120 , and a ratio of the tensile strength of the perforated area 110 to the tensile strength of the non-perforated area 120 is greater than or equal to 50% and less than or equal to 96%.

[0125] And / or, a ratio of the elongation at break of the perforated area 110 to the elongation at break of the non-perforated area 120 is greater than or equal to 50% and less than or equal to 98%.

[0126] That is to say, the tensile strength and elongation at break of the perforated area 110 are lower than those of the non-perforated area 120, and when the first pole piece 100 is subjected to a uniformity test, the fracture is located in the perforated area 110, and the uniformity S of the fracture is greater than 80%. The non-perforated area 120 may include a straight section of an unperforated area, or the non-perforated area 120 may also include an arc section.

[0127] In a possible implementation, the tensile strength of the perforated 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-perforated area 120 is greater than or equal to 20 MPa and less than or equal to 35 MPa. And / or, the elongation at break of the perforated area 110 is greater than or equal to 1% and less than or equal to 3%. And / or, the elongation at break of the perforated area 120 is greater than or equal to 2% and less than or equal to 4.5%.

[0128] With such arrangement, while ensuring the strength of the first pole piece 100 that meets normal use, the tensile strength of the perforated area 110 will be lower than the tensile strength of the non-perforated area 120, and the elongation at break of the perforated area 110 will be lower than the elongation at break of the non-perforated area 120. As a result, when the first pole piece 100 is subjected to a uniformity test, the fracture is located within the perforated area 110, further ensuring the uniformity of the first pole piece 100 when it breaks, reducing the short-circuit points generated when the battery composed of the first pole piece 100 is broken by a heavy object impact, thereby improving the safety of the battery.

[0129] Exemplarily, the tensile strength of the perforated area 110 may be any one of 10 MPa, 12 MPa, 15 MPa, 20 MPa, and 25 MPa, or may be within any two numerical ranges. And / or, the tensile strength of the non-perforated area 120 may be any one of 20 MPa, 24 MPa, 28 MPa, 30 MPa, and 35 MPa, or may be within any two numerical ranges. And / or, the elongation at break of the perforated area 110 may be any one of 1%, 1.2%, 1.5%, 2%, and 3%, or may be within any two numerical ranges. And / or, the elongation at break of the non-perforated area 120 may be any one of 2%, 2.1%, 2.8%, 3%, and 4.5%, or may be within any two numerical ranges.

[0130] The following is a brief description of the battery preparation process.

[0131] 1. Prepare the second pole piece. The slurry of the second pole piece is lithium cobalt oxide (LCO): conductive carbon black (SP): polyvinylidene fluoride (PVDF) = 97:1:2, and the solvent used is N-methylpyrrolidone (NMP). After stirring and mixing evenly, the slurry is coated on the second current collector and dried to obtain the second pole piece.

[0132] 2. Prepare the first pole piece 100. The slurry of the first pole piece 100 is graphite: styrene-butadiene rubber (SBR): carboxymethyl cellulose (CMC) = 95:3:2, and the solvent used is deionized water. After stirring and mixing evenly, the slurry is coated on the first current collector 130, and the first pole piece 100 is obtained after drying.

[0133] 3. Performing a hole forming process on the first pole piece 100 , wherein the structural parameters of the hole structure 111 of each embodiment and each comparative example can be referred to as shown in Table 1.

[0134] 4. The first pole piece 100 and the second pole piece are subjected to processes such as rolling, slitting, sheeting, lamination (or winding), packaging, liquid injection, formation, capacity division, and OCV to prepare a battery.

[0135] Table 1 Structural parameters

[0136]

[0137]

[0138] The following describes the relevant test performance of the first pole piece provided in the embodiment of the present application in combination with relevant tests.

[0139] 1. Tensile strength test

[0140] Disassemble the fresh battery, take out the first pole piece 100, cut the first pole piece 100 into small strips with a width of 24 mm (that is, used to test the extension dimension f of the first pole piece 100 along the second direction Y) along the second direction Y, test the thickness b of the first pole piece 100, and use a universal material mechanical testing machine to test its tensile strength and elongation at break, where the gauge length is 50 mm and the tensile speed is 50 mm / min.

[0141] 2. Regularity test

[0142] Based on the above tensile strength test, the distance h between the peak and the trough of the fracture of each comparative example and each embodiment is collected, and the uniformity S of the fracture of each comparative example and each embodiment is calculated.

[0143] 3. Heavy object impact test

[0144] Place the battery at room temperature, charge it at a constant current of 1C to a voltage of 4.5V, then charge it at a constant voltage until the current drops to 0.05C, stop charging, and then discharge it at a constant current of 1C to 3.0V. Repeat this cycle for 5T. Perform a heavy object impact test within 24 hours after the battery is fully charged for the last time.

[0145] Place the battery on a plane and place a steel column with a diameter of 15.8±0.2mm at the center of the battery with the longitudinal axis of the steel column parallel to the plane. Allow a weight of 9.1±0.1kg to fall freely from a height of 610±25mm onto the steel column above the center of the battery. Observe for 6 hours after the test is completed. If the battery does not catch fire or explode, it is considered passed.

[0146] Table 2 Test results

[0147]

[0148]

[0149] It can be seen from Table 1 and Table 2 above that the first pole pieces 100 of Examples 1 to 21 have all been subjected to a pore-forming treatment, and the structural parameters and arrangement of the hole structure 111 meet the requirements. Therefore, when Examples 1 to 21 are subjected to a uniformity test, the uniformity of the fracture is greater than 90%, thereby making the first pole pieces 100 of Examples 1 to 21 have a higher pass rate in the heavy object impact test. Therefore, the battery of this embodiment has a higher safety.

[0150] It can be understood that, when the first spacing L2, the second spacing W2, and the extension size W1 of the hole structure 111 along the first direction X are the same, the larger the extension size L1 of the hole structure 111 along the second direction Y, the more conducive to improving the uniformity of the first pole piece 100. When the second spacing W2, the extension size W1 of the hole structure 111 along the first direction X, and the extension size L1 of the hole structure 111 along the second direction Y are the same, the larger the first spacing L2, the more conducive to improving the uniformity of the first pole piece 100. When at least two of the first spacing L2, the second spacing W2, the extension size W1 of the hole structure 111 along the first direction X, and the extension size L1 of the hole structure 111 along the second direction Y are different, the larger L1 / W1 is, the more conducive to improving the uniformity of the first pole piece 100, the larger W2 / L2 is, the more conducive to improving the uniformity of the first pole piece 100, and the smaller L1 / L2 is, the more conducive to improving the uniformity of the first pole piece 100.

[0151] However, in Comparative Example 1, no hole-making treatment is performed, and the tensile strength and elongation at break of the first pole piece 100 cannot be reduced, resulting in a fracture uniformity of less than 70%, which leads to a low pass rate of the heavy object impact test of the first pole piece 100. In Comparative Example 2, the extension dimension L1 of the hole structure 111 along the second direction Y is smaller than the extension dimension W1 of the hole structure 111 along the first direction X, and the effect of the hole structure 111 in reducing the tensile strength and elongation at break of the first pole piece 100 in the second direction Y is limited, resulting in a fracture uniformity of less than 80% in Comparative Example 2. In Comparative Example 3, the first spacing L2 is larger than the second spacing W2, and the effect of the hole structure 111 in reducing the tensile strength and elongation at break of the first pole piece 100 in the second direction Y is limited. Therefore, the fracture uniformity of Comparative Example 3 is less than 80%.

[0152] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery, characterized in that: A first pole piece is included, and when two sides of the first pole piece along a first direction are subjected to a tensile force along the first direction, the first pole piece is broken into a first sheet and a second sheet, and a side where the first sheet and the second sheet are close to each other has a fracture, and the fracture extends along the second direction, and the uniformity S of the fracture is S=1-h / f, and the uniformity S satisfies: S>80%; Among them, f is the extension length of the first pole piece used for testing along the second direction, h is the distance between the crest of the fracture and the trough of the fracture, and the first direction is perpendicular to the second direction.

2. The battery according to claim 1, characterized in that A distance h between a wave crest of the fracture and a wave trough of the fracture satisfies: 0≤h≤5mm.

3. The battery according to claim 1 or 2, characterized in that: The first pole piece includes a straight section, the straight section has a perforated area, the perforated area has at least two hole structures, at least two of the hole structures are arranged along the second direction, and the fracture passes through at least one of the hole structures; And / or, the straight section has a notch, the notch extends along the second direction, and the fracture at least partially overlaps with the notch.

4. The battery according to claim 3, characterized in that The extension dimension L1 of a single hole structure along the second direction and the extension dimension W1 of the hole structure along the first direction satisfy: 1≤L1 / W1<10; And / or, an extension dimension L1 of the hole structure along the second direction and an extension dimension W1 of the hole structure along the first direction satisfy: 50 μm<W1≤L1<2000 μm.

5. The battery according to claim 3, characterized in that The distance h between the wave crest of the fracture and the wave trough of the fracture and the extension dimension W1 of the hole structure along the first direction satisfy: h≤W1.

6. The battery according to claim 4, characterized in that In the second direction, in the same row of the hole structures, there is a first spacing L2 between two adjacent hole structures, and the first spacing L2 and the second spacing W2 satisfy: 1≤W2 / L2<500; And / or, in the first direction, the perforated area has at least two rows of the hole structures, and there is a second spacing W2 between two adjacent rows of the hole structures, and the first spacing L2 and the second spacing W2 satisfy: 10 μm<L2≤W2<5000 μm.

7. The battery according to claim 6, characterized in that The extension dimension L1 of the hole structure along the second direction and the first spacing L2 satisfy: 0.2<L1 / L2<10; And / or, an extension dimension W1 of the hole structure along the first direction and the second spacing W2 satisfy: 0.5<W2 / W1<100.

8. The battery according to claim 3, characterized in that In the first direction, an extension dimension W3 of the perforated area and an extension dimension W4 of the first pole piece satisfy: 30%≤W3 / W4≤100%.

9. The battery according to claim 3, characterized in that The first pole piece further includes an arc segment, and the arc segment is connected to two opposite sides of the straight segment along the second direction; In the first direction, an extension dimension W3 of the perforated area and an extension dimension W4 of the first pole piece satisfy: 30%≤W3 / W4≤100%.

10. The battery according to claim 8 or 9, characterized in that: In the first direction, the perforated area is centrally arranged on the first pole piece.

11. The battery according to claim 3, characterized in that The area S1 of all the hole structures and the area S2 of the first pole piece satisfy: 0.1%≤S1 / S2≤20%; The area of ​​all the hole structures is S1=a(1)+a(2)+…+a(n), where n is the number of the hole structures.

12. The battery according to claim 3, characterized in that The first pole piece includes a first current collector and a first active material layer, the first active material layer is disposed on at least one side of the first current collector, and the hole structure is disposed on at least one of the first active material layer and the first current collector; And / or, the notch is provided in at least one of the first active material layer and the first current collector.

13. The battery according to claim 12, characterized in that The pore structure is provided in the first active material layer, and an extension dimension H1 of the pore structure along the third direction and an extension dimension H2 of the first active material layer along the third direction satisfy: 0.3≤H1 / H2≤1; Alternatively, the hole structure is provided in the first current collector, and an extension dimension H1 of the hole structure along the third direction and an extension dimension H3 of the first current collector along the third direction satisfy: 0.5≤H1 / H3≤1; Alternatively, the hole structure passes through two opposite sides of the first pole piece.

14. The battery according to claim 3, characterized in that The shape of the hole structure includes at least one of a circle, an ellipse, a diamond and a rectangle.

15. The battery according to claim 3, characterized in that The first pole piece further includes a non-perforated area, and a ratio of the tensile strength of the perforated area to the tensile strength of the non-perforated area is greater than or equal to 50% and less than or equal to 96%; And / or, the ratio of the elongation at break of the perforated area to the elongation at break of the non-perforated area is greater than or equal to 50% and less than or equal to 98%.

16. The battery according to claim 15, characterized in that The tensile strength of the punching area is greater than or equal to 10Mpa and less than or equal to 25Mpa; And / or, the tensile strength of the non-perforated area is greater than or equal to 20 MPa and less than or equal to 35 MPa; and / or, the elongation at break of the perforated area is greater than or equal to 1% and less than or equal to 3%; And / or, the elongation at break of the perforated area is greater than or equal to 2% and less than or equal to 4.5%.

Images