Electrode plate, electrode assembly and battery cell

Abstract

The utility model provides a pole piece, an electrode assembly and a battery cell, and relates to the technical field of batteries. The pole piece comprises a current collector, an active material layer and a tab; the current collector comprises a main body and a protruding part which protrudes outwards from the edge part of the main body; the active material layer is arranged on the main body and the protruding part; the tabs are connected with the main body. The protruding part is arranged on the edge of the main body, so that the arrangement amount of the active material layer of the pole piece can be increased, the energy density of the electrode assembly can be improved, and the energy density of a battery cell can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a pole piece, an electrode assembly and a battery cell. BACKGROUND

[0002] The battery cell comprises a shell and an electrode assembly arranged in the shell. The electrode assembly can be divided into a laminated electrode assembly and a wound electrode assembly according to the forming mode. The laminated electrode assembly comprises a plurality of sequentially stacked separators, negative pole pieces, separators and positive pole pieces. However, the energy density of the current laminated electrode assembly is small. CONTENT OF THE UTILITY MODEL

[0003] Embodiments of the present application provide a pole piece, an electrode assembly and a battery cell, which can improve the energy density of the laminated electrode assembly.

[0004] In a first aspect, embodiments of the present application provide a pole piece, which comprises a current collector, an active material layer and a tab; the current collector comprises a main body and a protruding portion protruding outward from part of the edge of the main body; the active material layer is arranged on the main body and the protruding portion; and the tab is connected to the main body.

[0005] In an embodiment, the main body has a first edge Z and a second edge Z connected to each other, the first edge Z and the second edge Z are arranged at an included angle, the protruding portion protrudes outward from part of the first edge Z, and the protruding portion has two first edges B extending in the protruding direction, one of which is arranged in line with the second edge Z.

[0006] In an embodiment, an obtuse angle α is formed between the first edge B away from the second edge Z and the first edge Z, and satisfies: 90°<α≤135°.

[0007] In an embodiment, the distance between the side of the protruding portion away from the main body and the edge connected to the main body is H, and satisfies: 0<H≤2mm.

[0008] In an embodiment, the main body has a third edge Z, a first edge Z and a second edge Z connected in sequence, the third edge Z and the second edge Z are arranged at an included angle with the first edge Z; the tab is connected to the first edge Z, and the distance between the tab and the third edge Z is not equal to the distance between the tab and the second edge Z.

[0009] In an embodiment, the minimum distance between the tab and the third edge Z is dmin1, and 0≤dmin1≤20mm, or the minimum distance between the tab and the second edge Z is dmin2, and 0≤dmin2≤20mm.

[0010] In an embodiment, the distance between the tab and the third edge Z is d1, and the distance between the tab and the second edge Z is d2, and satisfies: |d1-d2|≥2mm.

[0011] In an embodiment, the body has a first edge Z and a third edge Z connected, the first edge Z is arranged at an angle with the third edge Z, one side of the tab is connected with the first edge Z, and the tab has two extension edges in the extension direction of the tab, one of the extension edges is arranged in line with the third edge Z.

[0012] In an embodiment, the connection part between the tab and the current collector has a first corner, a fillet R1 is arranged at the first corner, a fillet R2 is arranged at the rest of the corners of the tab, the radius of the fillet R1 is greater than the radius of the fillet R2; wherein the radius of at least one of the fillet R1 and the fillet R2 is gradually changed.

[0013] In an embodiment, the tab and the protrusion are located on the same side of the body.

[0014] In a second aspect, embodiments of the present application provide an electrode assembly, comprising a plurality of negative tabs, a plurality of positive tabs, and a plurality of separators; the plurality of positive tabs and the plurality of negative tabs are arranged alternately and stacked in sequence; the plurality of separators are used to insulate and separate adjacent two positive tabs and negative tabs; wherein the negative tab is the aforementioned tab.

[0015] In an embodiment, the positive tab has a positive tab, and the positive tab is arranged opposite to the protrusion in the stacking direction.

[0016] In an embodiment, the positive tab has a width dimension W1, and the protrusion has a dimension W2 in the direction of the width dimension W1 of the positive tab, and W2> W1 is satisfied.

[0017] In an embodiment, in the stacking direction, the thickness of the positive tab located at the head and tail positions is D1, and the thickness of the rest of the positive tabs is D2, and D1> D2 is satisfied.

[0018] In an embodiment, 16 μm≤D1≤25 μm, and 6 μm≤D2≤12 m.

[0019] In an embodiment, in the stacking direction, the thickness of the negative tab located at the head and tail positions is D3, and the thickness of the rest of the negative tabs is D4, and D3> D4 is satisfied.

[0020] In an embodiment, 12 μm≤D3≤30 μm, and 4 μm≤D4≤12 m.

[0021] In a third aspect, embodiments of the present application provide a battery cell, comprising a shell and the aforementioned electrode assembly; the shell has a receiving cavity; the electrode assembly is arranged in the receiving cavity; wherein the positive tab or the negative tab is connected with the shell.

[0022] The beneficial effects of embodiments of the present application are as follows:

[0023] In the embodiments of the present application, by arranging the protrusion on the edge of the main body, the setting amount of the active material layer of the pole piece can be increased, so that the energy density of the electrode assembly can be improved, and the energy density of the battery cell can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0025] Figure 1 is a structural schematic diagram of a pole piece provided by an embodiment of the present application;

[0026] Figure 2 is a side view of a pole piece provided by an embodiment of the present application;

[0027] Figure 3 is a structural schematic diagram of a current collector provided by an embodiment of the present application.

[0028] Figure 4 is a partial structural schematic diagram of a current collector provided by an embodiment of the present application;

[0029] Figure 5 is a structural schematic diagram of another pole piece provided by an embodiment of the present application;

[0030] Figure 6 is a structural schematic diagram of an electrode assembly provided by an embodiment of the present application;

[0031] Figure 7 is a side view of an electrode assembly provided by an embodiment of the present application;

[0032] Figure 8 is Figure 6 is an enlarged view of A in FIG. 7;

[0033] Figure 9 is a structural schematic diagram of a battery cell provided by an embodiment of the present application.

[0034] Explanation of reference signs:

[0035] 1-pole piece; 11-current collector; 111-main body; 112-protrusion; 113-first edge Z; 114-second edge Z; 115-third edge Z; 116-first edge B;

[0036] 12-active material layer; 13-tab; 131-extended edge; 14-first corner;

[0037] 2 - electrode assembly; 21 - negative tab; 22 - positive tab; 221 - positive tab ear; 23 - separator;

[0038] 3 - battery cell; 31 - shell; 32 - positive pole. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0040] In the present application, the orientation words such as "upper" and "lower" used without the opposite description generally refer to the upper and lower in the actual use or working state of the device, and specifically refer to the drawing surface direction in the drawings. Multiple refers to at least two. The terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise explicitly and specifically limited.

[0041] 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 broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the 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.

[0042] And the term "includes", "contains" or any other variant thereof is intended to cover non-exclusive inclusion, so that the product including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such product.

[0043] Before introducing the positive tab, the electrode assembly and the battery cell provided by the present application, the related technologies of the present application are described.

[0044] In the related art, an electric core includes a shell and an electrode assembly arranged in the shell. The electrode assembly can be divided into a laminated electrode assembly and a wound electrode assembly according to a forming mode. The laminated electrode assembly includes a plurality of separators, a negative electrode sheet, a separator and a positive electrode sheet which are sequentially stacked. In the production process of the laminated electrode assembly, in order to improve the reliability of the electric core, an insulating layer needs to be arranged on the edge of the positive electrode sheet to avoid lithium precipitation on the edge of the positive electrode sheet. Based on the existing insulating layer arrangement process, the minimum width of the insulating layer that can be arranged on the edge of the positive electrode sheet is 2 mm, and the minimum thickness of the insulating layer is 20 μm. The thickness of the positive electrode sheet is generally 100-160 μm. In the thickness direction of the positive electrode sheet, the arrangement of the insulating layer occupies 12.5%-20% of the thickness of the positive electrode sheet. Therefore, the capacity loss of the electric core is 1%-2%.

[0045] However, in consumer electronic products such as smart watches, AR glasses and the like, the size of the electric core used is not only small, but also has a large difference between the length and width. Correspondingly, the size of the electrode sheet constituting the electric core is also small, and the difference between the length and width is also large. If the problem of lithium precipitation on the edge of the positive electrode sheet is solved by arranging an insulating layer, the capacity loss of such an electric core will be more obvious.

[0046] Therefore, in order to improve the energy density of the electric core, especially the energy density of small-size electric cores, embodiments of the present application provide an electrode sheet, an electrode assembly and an electric core. The embodiments of the present application are described in detail as follows.

[0047] Please refer to Figures 1 to 3 , Figure 1 is a structural schematic diagram of an electrode sheet 1 provided by an embodiment of the present application, Figure 2 is a side view of the electrode sheet 1 provided by an embodiment of the present application, Figure 3 is a structural schematic diagram of a current collector 11. An embodiment of the present application provides an electrode sheet 1. The electrode sheet 1 includes a current collector 11, an active material layer 12 and a tab 13. The current collector 11 includes a main body 111 and a protruding portion 112 which is outwardly protruded from a part of the edge of the main body 111. The active material layer 12 is arranged on the main body 111 and the protruding portion 112. The tab 13 is connected with the main body 111.

[0048] It can be understood that the arrangement of the protruding portion 112 makes the structure of the electrode sheet 1 after removing the tab 13 be a special-shaped structure. For example, when the main body 111 is rectangular, the edge of the main body 111 is connected with the tab 13, and a part of the edge of the main body 111 is connected with the protruding portion 112.

[0049] It can be understood that the tab 13 and the current collector 11 can be integrally formed. For example, a part of a foil is used to arrange the active material layer 12, and the other part is left empty to serve as the tab 13. The tab 13 can also be welded with the current collector 11.

[0050] It can be understood that the main materials of the active material layer 12 of the positive electrode sheet 22 include but are not limited to lithium cobalt oxide, lithium nickel manganese cobalt oxide, lithium iron phosphate, a conductive agent, and a binder. The main materials of the active material layer 12 of the negative electrode sheet 21 include but are not limited to graphite, a conductive agent, and a binder.

[0051] In addition, in order to avoid the problem of lithium precipitation, the electrode sheet 1 provided in the embodiment can be a negative electrode sheet 21, so that more lithium intercalation sites can be provided for the battery cell 3 to effectively avoid the deposition and precipitation of lithium ions in the form of metallic lithium.

[0052] It can be understood that the protruding portion 112 occupies a space. In the electrode assembly 2 to which the electrode sheet 1 is applied, the protruding portion 112 is arranged opposite to the tab of the positive electrode sheet in the thickness direction of the electrode sheet 1, that is, the protruding portion 112 of the electrode sheet 1 provided in the embodiment can be arranged opposite to the tab of the positive electrode sheet, so that the space occupied by the protruding portion 112 is the space between the tabs of the positive electrode sheet, thereby not affecting the external dimensions of the battery cell 3.

[0053] In the embodiment, by arranging the protruding portion 112 at the edge of the main body 111, the amount of the active material layer 12 of the electrode sheet 1 can be increased, thereby improving the energy density of the electrode assembly 2 and the energy density of the battery cell 3.

[0054] In addition, when the electrode sheet 1 provided in the embodiment is a negative electrode sheet 21, by arranging the protruding portion 112 at the edge of the main body 111, the amount of lithium intercalation sites of the electrode assembly 2 can be increased, thereby effectively avoiding the deposition and precipitation of lithium ions in the form of metallic lithium and reducing the risk of lithium precipitation of the electrode assembly 2. In this way, the reliability of the battery cell 3 can be improved.

[0055] Please refer to Figure 4 , Figure 4 is a partial structure schematic view of the current collector 11 provided in the embodiment. In an embodiment, the main body 111 has a first edge Z113 and a second edge Z114 connected to each other. The first edge Z113 and the second edge Z114 are arranged at an angle. The protruding portion 112 is outwardly protruding from part of the first edge Z113, and the protruding portion 112 has two first edges B116 extending in the protruding direction. One of the first edges B116 is arranged in line with the second edge Z114.

[0056] It can be understood that the in-line arrangement means that in a plane parallel to the electrode sheet 1, the projection of the first edge B116 and the projection of the second edge Z114 are located on the same straight line.

[0057] It can be understood that, in order to reduce the stress concentration at each corner of the pole piece 1 and avoid the sharp corners of the pole piece 1 piercing the diaphragm 23 and the like, it is necessary to round the corners of the pole piece 1. However, when rounding the corners on the main body 111, part of the current collector 11 on which the active material layer 12 can be arranged will be lost.

[0058] Based on this, in the present embodiment, by arranging the first edge B116 to be collinear with the second edge Z114, the number of corners of the main body 111 can be reduced. In this way, on the one hand, the area of the active material layer 12 that can be arranged on the pole piece 1 can be increased, so that the amount of the active material layer 12 arranged on the pole piece 1 can be increased, thereby facilitating the improvement of the energy density of the electrode assembly 2; on the other hand, the corner processing of the pole piece 1 can be reduced, so that the stress concentration of the pole piece 1 can be reduced, thereby improving the stress state of the pole piece 1.

[0059] Please refer to Figure 4 In an embodiment, an obtuse angle α is formed between the first edge B116 away from the second edge Z114 and the first edge Z113. In this way, the stress concentration of the corner formed between the first edge B116 and the first edge Z113 can be reduced, so as to improve the stress state of the connection between the first edge B116 and the first edge Z113.

[0060] It can be understood that the obtuse angle α is located outside the protrusion 112.

[0061] Please refer to Figure 4 In an embodiment, 90° < α ≤ 135°.

[0062] It can be understood that the obtuse angle α includes but is not limited to 91°, 92°, 93°, 94°, 95°, 96°, 97°, 98°, 99°, 100°, 101°, 102°, 103°, 104°, 105°, 106°, 107°, 108°, 109°, 110°, 111°, 112°, 113°, 114°, 115°, 116°, 117°, 118°, 119°, 120°, 121°, 122°, 123°, 124°, 125°, 126°, 127°, 128°, 129°, 130°, 131°, 132°, 133°, 134°, 135°.

[0063] In the present embodiment, through the above arrangement, the obtuse angle α can be formed between the first edge B116 and the first edge Z113, and the protrusion 112 can have a larger area, so that more active material layers 12 can be arranged to improve the energy density of the electrode assembly 2.

[0064] Please refer to Figure 4In an embodiment, the distance between the side of the protrusion 112 away from the main body 111 and the edge of the main body 111 to which the protrusion 112 is connected is H, which satisfies: 0 < H ≤ 2 mm.

[0065] It can be understood that the distance H between the side of the protrusion 112 away from the main body 111 and the edge of the main body 111 to which the protrusion 112 is connected includes but is not limited to 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm.

[0066] It can be understood that the diaphragm 23 is used to insulate and separate the adjacent positive electrode sheet 22 and negative electrode sheet 21. In order to improve the reliability of the diaphragm 23 in insulating and separating the positive electrode sheet 22 and the negative electrode sheet 21, the diaphragm 23 will be arranged to exceed the edge of the main body 111, generally exceeding 2 mm.

[0067] Based on this, in the present embodiment, through the above arrangement, the protrusion 112 can be formed, which is conducive to improving the energy density of the electrode assembly 2, and the insulating and separating property between the electrode sheet 1 and the electrode sheet 1 of another polarity adjacent to the electrode sheet 1 can be effectively ensured, thereby improving the reliability of the electrode assembly 2.

[0068] It can be understood that if the diaphragm 23 exceeds the edge of the main body 111 by 1 mm, the maximum value of the distance H between the side of the protrusion 112 away from the main body 111 and the edge of the main body 111 to which the protrusion 112 is connected is 1 mm.

[0069] Please refer to Figure 1 In an embodiment, the main body 111 has a third edge Z115, a first edge Z113 and a second edge Z114 connected in sequence. The third edge Z115 and the second edge Z114 are arranged at an angle with the first edge Z113. The tab 13 is connected to the first edge Z113. The distance between the tab 13 and the third edge Z115 is not equal to the distance between the tab 13 and the second edge Z114. In this way, the assembler can determine whether the tab 13 of the electrode sheet 1 should be located on the left side or the right side of the main body 111 according to the two unequal distances, thereby improving the speed of assembling the electrode sheet 1 with the electrode sheet 1 of another polarity.

[0070] Please refer to Figure 1 In an embodiment, the minimum distance between the tab 13 and the third edge Z115 is dmin1, 0 ≤ dmin1 ≤ 20 mm, or the minimum distance between the tab 13 and the second edge Z114 is dmin2, 0 ≤ dmin2 ≤ 20 mm.

[0071] The minimum distance dmin1 between the tab 13 and the third edge Z115 includes but is not limited to 0, 0.1 mm, 1.2 mm, 2.3 mm, 3.4 mm, 4.5 mm, 5.6 mm, 6.7 mm, 7.8 mm, 8.9 mm, 10.0 mm, 11.1 mm, 12.2 mm, 13.3 mm, 14.4 mm, 15.5 mm, 16.6 mm, 17.7 mm, 18.8 mm, 20 mm.

[0072] The minimum distance dmin2 between the tab 13 and the second edge Z114 includes but is not limited to 0, 0.5 mm, 2.5 mm, 3.6 mm, 4.7 mm, 5.8 mm, 6.9 mm, 8.0 mm, 9.1 mm, 10.2 mm, 11.5 mm, 12.6 mm, 13.7 mm, 14.8 mm, 15.9 mm, 16.0 mm, 17.1 mm, 18.2 mm, 19.3 mm, 20 mm.

[0073] In the embodiment, by the above definition, the tab 13 is biased to one side of the main body 111, so that the assembler can determine whether the tab 13 of the pole piece 1 should be located on the left side or the right side of the main body 111 according to the distance between the tab 13 and the side of the main body 111, thereby improving the speed of assembling the pole piece 1 with another pole piece 1 of another polarity.

[0074] Please refer to Figure 1 In an embodiment, the distance between the tab 13 and the third edge Z115 is d1, and the distance between the tab 13 and the second edge Z114 is d2, satisfying |d1-d2|≥2 mm.

[0075] It can be understood that the absolute value of the interpolation between the distance d1 and the distance d2 includes but is not limited to 2 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3 mm.

[0076] It can be understood that when the tab 13 and the protrusion 112 are located on the same side of the main body 111, the tab 13 is arranged to be independent of the arrangement position of the protrusion 112.

[0077] In the embodiment, by the above definition, the assembler can directly observe the tab 13 with the naked eye, and can clearly distinguish whether the tab 13 is located on the left side or the right side of the pole piece 1, thereby improving the speed of assembling the pole piece 1 with another pole piece 1 of another polarity.

[0078] Please refer to Figure 5 , Figure 5is another schematic structural view of the tab 1 provided by the embodiments of the present application. In an embodiment, the main body 111 has a first edge Z113 and a third edge Z115 connected. The first edge Z113 is arranged at an angle with the third edge Z115. One side of the tab 13 is connected with the first edge Z113. Along the extension direction of the tab 13, the tab 13 has two extension edges 131, one of which is arranged in line with the third edge Z115.

[0079] It can be understood that, in order to reduce the stress concentration at each corner of the tab 1 and avoid the sharp corners of the tab 1 from piercing the diaphragm 23, etc., it is necessary to round the corners of the tab 1. When rounding the corners on the main body 111, part of the current collector 11 on which the active material layer 12 can be arranged will be lost.

[0080] Based on this, in the present embodiment, by arranging one of the extension edges 131 in line with the third edge Z115, the number of corners of the main body 111 can be reduced. In this way, on the one hand, the area of the active material layer 12 that can be arranged on the tab 1 can be increased, so that the amount of the active material layer 12 arranged on the tab 1 can be increased, thereby facilitating the improvement of the energy density of the electrode assembly 2; on the other hand, the corner processing of the tab 1 can be reduced, so that the parts where the stress of the tab 1 is more concentrated can be reduced, thereby improving the stress state of the tab 1.

[0081] In addition, by arranging one of the extension edges 131 in line with the third edge Z115, the burr and crack problems of the tab 1 caused by the need to round the corners on the side of the main body 111 close to the tab 13 can be avoided.

[0082] Please refer to Figure 1 or Figure 5 In an embodiment, the connection part between the tab 13 and the current collector 11 has a first corner 14. A rounding R1 is arranged at the first corner 14. A rounding R2 is arranged at the rest of the corners of the tab 1, and the radius of the rounding R1 is greater than the radius of the rounding R2.

[0083] For example, the radius of the rounding R2 is 0.3 mm, and the radius of the rounding R1 can be 2 mm.

[0084] Among them, the radius of at least one of the rounding R1 and the rounding R2 is gradually changed. By arranging the corners on the tab 1 to be gradually changed, both the sharp structures at each corner of the tab 1 can be prevented to avoid scratching the diaphragm, and the electrode assembly 2 assembled by the tab 1 can be guided when it is loaded into the shell 31 of the battery cell 3, thereby facilitating the smoothness of the assembly.

[0085] Specifically, the radius of the chamfer R1 is gradually changed, which can be gradually increased from the edge of the tab 13 to the edge of the body 111, or gradually decreased from the edge of the tab 13 to the edge of the body 111, or gradually decreased from a certain position of the chamfer R1 to the edge of the tab 13 and the edge of the body 111 respectively.

[0086] Specifically, the radius of the chamfer R2 is gradually changed, which can be gradually increased or decreased from one side edge of the body 111 to the other side edge of the body, or gradually decreased from a certain position of the chamfer R2 to the two edges of the body 111 respectively.

[0087] In the embodiment, through the above setting, the size of the connection between the tab 13 and the body 111 can be increased. In this way, not only the area of the tab 13 can be increased to increase the strength of the connection between the tab 13 and the body 111, so as to avoid the connection between the tab 13 and the body 111 from being broken due to welding, and the operability of welding the tab 13 can be improved, but also the flow area between the tab 13 and the body 111 can be increased to reduce the internal resistance of the battery cell 3.

[0088] Please refer to Figure 1 or Figure 5 In an embodiment, the tab 13 and the protrusion 112 are located on the same side of the body 111. In this way, the protrusion 112 and the tab 13 can share part of the height space, so as to reduce the space occupied by the protrusion 112, thereby facilitating the improvement of the structural compactness of the electrode assembly 2.

[0089] Please refer to Figure 6 and Figure 7 , Figure 6 is a structural schematic diagram of an electrode assembly 2 provided by an embodiment of the present application, Figure 7 is a side view of an electrode assembly 2 provided by an embodiment of the present application. An electrode assembly 2 is provided by an embodiment of the present application. The electrode assembly 2 includes a plurality of negative tabs 21, a plurality of positive tabs 22, and a plurality of separators 23. The plurality of positive tabs 22 and the plurality of negative tabs 21 are alternately and sequentially arranged and stacked. The plurality of separators 23 are used to insulate and separate adjacent two positive tabs 22 and negative tabs 21. Among them, the negative tab 21 is the tab 1 described above.

[0090] It can be understood that the protrusion 112 is arranged adjacent to the part on the positive tab 22 where lithium is easily deposited.

[0091] In an embodiment, by using the tab 1 provided by some embodiments of the present application as the negative tab 21, the energy density of the electrode assembly 2 can be improved, so as to improve the energy density of the battery cell 3.

[0092] In an embodiment, the positive tab 22113 is arranged opposite to the protrusion 112 in the stacking direction. In this way, the active material layer 12 of the protrusion 112 of the negative tab 21 can be arranged opposite to the active material layer 12 on the positive tab 22113 of the positive tab 22, so as to effectively avoid the lithium ions at the edge of the positive tab 22 from being deposited in the form of metallic lithium, thereby reducing the risk of lithium deposition of the electrode assembly 2, and improving the reliability of the battery cell 3.

[0093] In addition, during the coating of the positive active material layer 12, the coating position is difficult to be misaligned in four directions, i.e., front, back, left and right, with respect to the current collector 11 of the positive tab 22. Such misalignment can cause residual positive active material on the tab 1 tab 13 formed by die-cutting the positive tab 22 after coating. Therefore, in the embodiment, by arranging the positive tab 22113 opposite to the protrusion 112, the risk of lithium deposition caused by residual positive active material on the positive tab 22113 can be reduced.

[0094] Please refer to Figure 8 , Figure 8 is Figure 6 an enlarged view of A in FIG. 11. In an embodiment, the positive tab 22113 has a width dimension W1. In the direction of the width dimension W1 of the positive tab 22113, the protrusion 112 has a dimension W2, which satisfies: W2>W1. In this way, the overlapping amount of the protrusion 112 and the positive tab 22113 is increased, so as to effectively avoid the lithium ions at the edge of the positive tab 22 from being deposited in the form of metallic lithium.

[0095] wherein the dimension W2 is the dimension of the side of the protrusion 112 away from the main body 111.

[0096] In an embodiment, the thickness of the positive tab 22 at the first and last positions in the stacking direction is D1, and the thickness of the remaining positive tabs 22 is D2, which satisfies: D1>D2.

[0097] It can be understood that after the positive tab 22, the separator 23 and the negative tab 21 are stacked in sequence, the tabs 13 of the positive tab 22 are welded together by ultrasonic waves. Since ultrasonic welding is to make the surfaces of the materials to be welded rub against each other by using high-frequency vibration energy, so as to generate heat, and realize the connection of the materials under the action of pressure.

[0098] Therefore, when the positive tab 22113 is welded together, the vibration acting on the positive tab 22 can easily cause the positive tab 22 at the first and last positions in the stacking direction to be damaged or even broken. Based on this, in the embodiment, the thickness D1 of the positive tab 22 at the first and last positions is set to be larger, so as to improve the strength of the positive tab 22 at the first and last positions, and avoid damage during welding.

[0099] In an embodiment, 16 μm≤D1≤25 μm, 6 μm≤D2≤12 m. In this way, the positive electrode sheet 22 located at the head and tail positions and other positive electrode sheets 22 between the positive electrode sheets 22 located at the head and tail positions can have appropriate thickness dimensions, so as to ensure smooth welding while controlling the material cost of the positive electrode sheet 22.

[0100] In an embodiment, 16 μm≤D1≤25 μm, 6 μm≤D2≤12 m. In this way, the positive electrode sheet 22 located at the head and tail positions and other positive electrode sheets 22 between the positive electrode sheets 22 located at the head and tail positions can have appropriate thickness dimensions, so as to ensure smooth welding while controlling the material cost of the positive electrode sheet 22.

[0101] In an embodiment, 16 μm≤D1≤25 μm, 6 μm≤D2≤12 m. In this way, the positive electrode sheet 22 located at the head and tail positions and other positive electrode sheets 22 between the positive electrode sheets 22 located at the head and tail positions can have appropriate thickness dimensions, so as to ensure smooth welding while controlling the material cost of the positive electrode sheet 22.

[0102] In an embodiment, the thickness of the negative electrode sheet 21 located at the head and tail positions is D3, and the thickness of the other negative electrode sheets 21 is D4, along the stacking direction, satisfying: D3>D4.

[0103] It can be understood that after the positive electrode sheet 22, the separator 23 and the negative electrode sheet 21 are sequentially stacked, the ultrasonic wave is used to weld the tabs 13 of the negative electrode sheet 21 into one body. Since the ultrasonic welding is to use high-frequency vibration energy to make the surfaces of the materials to be welded rub against each other, thereby generating heat, and realizing the connection of the materials under the action of pressure.

[0104] Therefore, when the negative tabs 13 are welded into one body, the vibration acting on the negative electrode sheet 21 is easy to cause the negative electrode sheet 21 located at the head and tail positions in the stacking direction to be damaged or even broken. Based on this, in the embodiment, the thickness D3 of the negative electrode sheet 21 located at the head and tail positions is set to be larger, so as to improve the strength of the negative electrode sheet 21 located at the head and tail positions, so as to avoid damage in the welding process.

[0105] In an embodiment, 16 μm≤D1≤25 μm, 6 μm≤D2≤12 m. In this way, the positive electrode sheet 22 located at the head and tail positions and other positive electrode sheets 22 between the positive electrode sheets 22 located at the head and tail positions can have appropriate thickness dimensions, so as to ensure smooth welding while controlling the material cost of the positive electrode sheet 22.

[0106] The thickness D3 includes, but is not limited to, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 30 μm, 14.5 μm, 17.5 μm, 20.5 μm, 23.5 μm, 26.5 μm, 28.5 μm, 30 μm.

[0107] The thickness D4 includes, but is not limited to, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, 11 μm, 12 μm, 4.8 μm, 6.2 μm, 7.8 μm, 9.2 μm, 10.8 μm, 12 μm.

[0108] Please refer to Figure 9 , Figure 9 FIG. 1 is a structural schematic diagram of an electric core 3 provided by an embodiment of the present application. The embodiment of the present application provides an electric core 3. The electric core 3 includes a shell 31 and the aforementioned electrode assembly 2. The shell 31 has a receiving cavity. The electrode assembly 2 is arranged in the receiving cavity. One of the positive electrode sheet 22 and the negative electrode sheet 21 is electrically connected with the shell 31, and the other is electrically connected with a pole arranged on the shell 31.

[0109] Specifically, the negative electrode sheet 21 is electrically connected with the shell 31, and the positive electrode sheet 22 is insulated and isolated from the shell 31.

[0110] Specifically, the shell 31 is provided with a positive pole 32, which is insulated and isolated from the shell 31. The positive electrode sheet 22 is electrically connected with the positive pole 32.

[0111] In addition, the positive electrode sheet 22 and the negative electrode sheet 21 are provided with a fillet at a position corresponding to the corner of the shell 31. The fillet on the positive electrode sheet 22 and the negative electrode sheet 21 is equal in diameter to the fillet on the inner wall of the shell 31 adjacent to the fillet, so that the circumferential line of the fillet on the positive electrode sheet 22 and the negative electrode sheet 21 is deformed and fitted with the circumference of the fillet on the inner wall of the shell 31 adjacent to the fillet. In this way, the electrode assembly 2 can be in full contact with the inner wall of the shell 31, so that the size of the electrode assembly 2 in the inner cavity of the shell 31 can be increased to improve the capacity density. In addition, when the electric core 3 is subjected to various safety risks such as vibration and impact, the electrode assembly 2 can be uniformly stressed, so that the risk of deformation and cracking of the positive electrode sheet 22 and the negative electrode sheet 21 can be reduced.

[0112] The electric core 3 is applied to consumer electronic products, such as smart watches and AR glasses.

[0113] In the embodiments of the present application, by adopting the electrode assembly 2 provided by some embodiments of the present application, the setting amount of the active material layer 12 of the tab 1 can be increased, so that the energy density of the battery cell 3 can be improved. The technical solutions and technical effects of the present application are described in detail below through specific embodiments. The following embodiments are only part of the embodiments of the present application, and do not specifically limit the present application.

[0114] The present embodiment aims to investigate the influence of the tab applied to the battery cell 3 on the capacity of the battery cell 3.

[0115] The test content of the embodiments is specifically described as follows:

[0116] I. Test related description

[0117] The device used for the test is a power battery tester, which can be of the model CTE-8008-5V200A.

[0118] The test environment temperature is 25±2℃.

[0119] Test object one: the battery cell in the related art, which has a length of 45mm, a width of 10mm, a thickness of 3.2mm, and a volume of 1440mm 3 .

[0120] Test object two: the battery cell 3 provided by the embodiments of the present application, which has a length of 45mm, a width of 10mm, a thickness of 3.2mm, and a volume of 1440mm 3 .

[0121] II. Test

[0122] The test object one is subjected to the capacity test, and the 0.2 capacity of the test object one is 209mAh.

[0123] The test object two is subjected to the capacity test, and the 0.2 capacity of the test object two is 215mAh.

[0124] III. Comparison description

[0125] It can be known from the test results that, under the same volume, the capacity of the battery cell 3 provided by the embodiments of the present application is greater than that of the battery cell in the related art, and the capacity of the battery cell 3 provided by the embodiments of the present application is 2.9% more than that of the battery cell in the related art. Therefore, it can be known that the tab provided by the embodiments of the present application can effectively increase the energy density of the battery cell.

[0126] The 0.2c capacity refers to the actual amount of electricity that the battery cell can accommodate after the battery cell is subjected to the capacity test by charging and discharging at a current of 0.2 times the rated capacity.

[0127] The above has carried out the detailed introduction to the embodiment of the application, the principle and implementation mode of the application have been described by applying specific examples in this paper, the above embodiment explanation is only for helping understanding the core idea of the application; at the same time, for the person skilled in the art, according to the idea of the application, the specific implementation mode and application range will have the change, and the above is described, the content of the specification should not be understood as the limitation of the application.

Claims

1. A pole piece, characterized in that, The collector includes: a collector body including a main body and a protrusion outwardly protruding from a portion of an edge of the main body; an active material layer disposed on the main body and the protrusion; a tab connected to the main body.

2. The pole piece of claim 1, wherein The main body has a first edge Z and a second edge Z connected to each other, the first edge Z and the second edge Z are arranged at an included angle, the protrusion outwardly protrudes from a portion of the first edge Z, and the protrusion has two first edges B extending in the protruding direction, one of the first edges B is arranged in line with the second edge Z.

3. The pole piece of claim 2, wherein An obtuse included angle α is formed between the first edge B away from the second edge Z and the first edge Z, which satisfies: 90° < α ≤ 135°.

4. The pole piece of claim 1, wherein The distance between the side of the protrusion away from the main body and the edge connected to the main body is H, which satisfies: 0 < H ≤ 2 mm.

5. The pole piece of any one of claims 1-4, wherein, The main body has a third edge Z, a first edge Z and a second edge Z connected in sequence, the third edge Z and the second edge Z are arranged at an included angle with the first edge Z; The tab is connected to the first edge Z, and the distance between the tab and the third edge Z is not equal to the distance between the tab and the second edge Z.

6. The pole piece of claim 5, wherein The minimum distance between the tab and the third edge Z is dmin1, 0 ≤ dmin1 ≤ 20 mm, or the minimum distance between the tab and the second edge Z is dmin2, 0 ≤ dmin2 ≤ 20 mm.

7. The pole piece of claim 5, wherein The distance between the tab and the third edge Z is d1, and the distance between the tab and the second edge Z is d2, which satisfies: |d1-d2| ≥ 2 mm.

8. The pole piece of any one of claims 1-4, wherein, The main body has a first edge Z and a third edge Z connected to each other, the first edge Z and the third edge Z are arranged at an included angle, one side of the tab is connected to the first edge Z, and along the extension direction of the tab, the tab has two extension edges, one of the extension edges is arranged in line with the third edge Z.

9. The pole piece of any one of claims 1-4, wherein, The connection position between the tab and the collector has a first corner, a fillet R1 is arranged at the first corner, a fillet R2 is arranged at the rest of the corners of the tab, and the radius of the fillet R1 is greater than the radius of the fillet R2. At least one of the radius of the fillet R1 and the radius of the fillet R2 is gradually changed.

10. The pole piece of any one of claims 1-4, wherein, The tab and the protrusion are located on the same side of the main body.

11. An electrode assembly, characterized by, The collector includes: a plurality of negative tabs; a plurality of positive tabs arranged in sequence and alternately with the plurality of negative tabs; a plurality of separators for insulating and separating adjacent two positive tabs and negative tabs; The negative tab is the tab of any one of claims 1-10.

12. The electrode assembly of claim 11, wherein, The positive tab has a positive tab, and the positive tab is arranged opposite to the protrusion along the stacking direction.

13. The electrode assembly of claim 12, wherein, The positive tab has a width dimension W1, and the protrusion has a dimension W2 in the direction of the width dimension W1 of the positive tab, which satisfies: W2 > W1.

14. The electrode assembly of any one of claims 11-13, wherein, Along the stacking direction, the thickness of the positive tab located at the head and tail positions is D1, and the thickness of the rest of the positive tabs is D2, which satisfies: D1 > D2.

15. The electrode assembly of claim 14, wherein, 16 μm≤D1≤25 μm, 6 μm≤D2≤12 m.

16. The electrode assembly of any one of claims 11-13, wherein, In the stacking direction, the thickness of the negative electrode sheet at the head and tail positions is D3, and the thickness of the remaining negative electrode sheets is D4, satisfying: D3>D4.

17. The electrode assembly of claim 16, wherein, 12 μm≤D3≤30 μm, 4 μm≤D4≤12 m.

18. An electric cell, characterized by comprising: a housing having a receiving cavity; and the electrode assembly as claimed in any one of claims 11-17 disposed within the receiving cavity.

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