Pole piece, battery cell and battery

Abstract

The invention provides a pole piece, a battery cell and a battery, the pole piece comprises a current collector and a tab, the current collector comprises a support layer and a conductive layer, the conductive layer is at least located on one side surface of the support layer, the tab comprises a main body part and a connecting part adjacent to the main body part, the connecting part is connected with the conductive layer, and the main body part extends in a direction away from the current collector; wherein in the MD direction of the pole piece, the length of the connecting part of the pole lug is greater than that of the main body part of the pole lug. According to the arrangement, the local part of the tab is lengthened, so that the whole tab is divided into the main body part and the connecting part, the main body part still maintains the original specification and size and does not influence the original basic function of the tab, and the connecting part with relatively large length and the conductive layer of the current collector have a welding relationship, so that the current-carrying capacity of the formed welding part is improved; the composite current collector can reduce charging and discharging temperature rise, and solves the problem that the current-carrying capability of the tab welding part of the composite current collector in the prior art is insufficient, and the temperature rise of the welding part is easily caused.

Description

Electrodes, cells and batteries Technical Field

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

[0002] In order to improve the nail penetration performance and impact resistance of battery cells, the battery industry has begun to transform the current collector from metal foil to a composite current collector, which is composed of a polymer material layer and a metal layer stacked together.

[0003] Due to the unique structure of the composite current collector, the tabs on the composite current collector are typically welded to the composite current collector. However, under high-current charging and discharging requirements, the welding point between the tab and the composite current collector has insufficient current-carrying capacity, which can easily cause the temperature at the welding point to rise, posing a safety hazard.

[0004] Application Contents

[0005] In view of this, the present application provides a pole piece, a battery cell and a battery to solve the problem in the prior art that the current carrying capacity of the pole tab welding point of the composite current collector is insufficient, which easily leads to the temperature increase of the welding point.

[0006] In order to achieve the above objectives, this application provides the following technical solutions:

[0007] A pole piece, comprising:

[0008] A current collector comprising a support layer and a conductive layer, wherein the conductive layer is located on at least one side of the support layer;

[0009] a tab, comprising a main body portion and a connecting portion adjacent to the main body portion, wherein the connecting portion is connected to the conductive layer, and the main body portion extends in a direction away from the current collector;

[0010] Wherein, in the MD direction of the pole piece, the length of the connecting portion of the pole tab is greater than the length of the main body portion of the pole tab.

[0011] Optionally, the conductive layer is provided on both side surfaces of the support layer, and a single pole ear includes at least a first foil and a second foil respectively connected to the conductive layers on both sides. In the TD direction of the pole piece, the width of the first foil is greater than the width of the second foil, and at least a partial area of ​​the main body is formed only by the first foil.

[0012] Optionally, the connecting portion is formed by welding the first foil, the current collector and the second foil;

[0013] The connecting portion between the main body and the connecting portion is formed by welding the first foil, the current collector, and the second foil, and / or by welding the first foil and the second foil.

[0014] Optionally, the tabs are provided in plurality and include type I tabs and type II tabs, and the plurality of type I tabs and the plurality of type II tabs are alternately distributed along the MD direction of the pole piece, and in the MD direction of the pole piece, the length of the main body of the type I tab is S1, the length of the main body of the type II tab is S2, the length of the connecting portion of the type I tab is S3, and the length of the connecting portion of the type II tab is S4; wherein,

[0015] S2>S1;

[0016] Alternatively, S2=S1, and S4>S3.

[0017] Optionally, along the TD direction of the pole piece, the surface of the conductive layer is provided with a coating portion, a ceramic portion and an empty current collector area in sequence, the connecting portion of the pole tab covers part of the ceramic portion, and the connecting portion of the pole tab is connected to the conductive layer in the empty current collector area.

[0018] Optionally, the conductive layer is provided on both sides of the support layer, and a single tab includes a first foil and a second foil; wherein,

[0019] On the current collector, the first foil and the second foil are respectively welded to the conductive layers on both sides, and the first foil, the current collector and the second foil form a welding area;

[0020] Outside the current collector, the first foil and the second foil are at least partially welded to form two welding areas.

[0021] Optionally, at least the surface of the first welding area is coated with an insulating layer, and the first welding area and the second welding area are arranged adjacent to each other.

[0022] Optionally, the tab is welded to the current collector, and a welding area is formed on the tab. In the TD direction of the pole piece, the width of the welding area of ​​the first-type tab is W1, and the width of the welding area of ​​the second-type tab is W2; wherein,

[0023] W1 satisfies 1mm≤W1≤10mm;

[0024] And / or, W1 and W2 satisfy 0.5≤W1 / W2≤1.5.

[0025] Optionally, S1 satisfies 4mm≤S1≤50mm;

[0026] and / or, S2 satisfies 4 mm ≤ S2 ≤ 50 mm;

[0027] And / or, S1 and S2 satisfy 0.5≤S1 / S2≤1.

[0028] Optionally, S3 satisfies 6mm≤S3≤200mm;

[0029] And / or, S4 satisfies 6mm≤S4≤300mm.

[0030] Optionally, in the MD direction of the pole piece, the spacing distance between the type 1 pole tab and the type 2 pole tab is L1, and L1 satisfies 3mm≤L1≤100mm.

[0031] Optionally, in the TD direction of the pole piece, the height of the connecting portion of the type 1 pole tab is H1, and the height of the connecting portion of the type 2 pole tab is H2; wherein,

[0032] H1 and W1 satisfy 0.05≤H1 / W1≤0.95;

[0033] And / or, H2 and W2 satisfy 0.05≤H2 / W2≤0.95.

[0034] Optionally, H1 and W1 satisfy 0.3≤H1 / W1≤0.6;

[0035] And / or, H2 and W2 satisfy 0.3≤H2 / W2≤0.6.

[0036] Optionally, in the TD direction of the pole piece, the width of the ceramic portion is Wt, and the width of the portion of the ceramic portion covered by the pole tab is Wf; wherein,

[0037] Wt satisfies 1mm≤Wt≤10mm;

[0038] and / or, Wf satisfies 0<Wf≤5mm;

[0039] And / or, Wt and Wf satisfy 0.1≤Wf / Wt≤0.9.

[0040] Optionally, in the TD direction of the electrode, the width of the first welding zone is d1, the width of the second welding zone is d2, and the width of the welding zone formed by the first welding zone and the second welding zone is d; wherein,

[0041] d1 satisfies 0.5mm≤d1≤20mm;

[0042] and / or, d2 satisfies 0.2 mm ≤ d2 ≤ 10 mm;

[0043] and / or, d satisfies 2mm≤d≤50mm;

[0044] And / or, d2 and d satisfy 0.1≤d2 / d≤0.7.

[0045] Optionally, the first welding zone and the second welding zone form a welding zone, and in the TD direction of the pole piece, the distance between the outer edge of the connecting portion of the pole tab and the inner edge of the welding zone is D1, and the distance between the outer edge of the connecting portion of the pole tab and the outer edge of the welding zone is D2; wherein,

[0046] D1 satisfies 0.5mm≤D1≤20mm;

[0047] and / or, 0.5 mm ≤ D2 ≤ 20 mm;

[0048] And / or, D1 and D2 satisfy 0.1≤D1 / D2≤0.7.

[0049] Optionally, the connection between the connecting portion of the tab and the current collector is an arc with a radius of R1, the connection between the main body of the tab and the connecting portion is an arc with a radius of R2, and the outer edge angle of the connecting portion of the tab is an arc with a radius of R3; wherein,

[0050] R1 satisfies 0.5mm≤R1≤10mm;

[0051] and / or, R2 satisfies 0.5 mm ≤ R2 ≤ 10 mm;

[0052] And / or, R3 satisfies 0.2mm≤R3≤5mm.

[0053] Optionally, in the TD direction of the pole piece, the width of the current collector is D3, the height of the connecting portion of the pole tab is D4, and D3 and D4 satisfy 0.1≤D4 / D3≤0.5.

[0054] Optionally, the thickness of the current collector is a, the thickness of the first foil is b1, the thickness of the second foil is b2, the thickness of the first welding zone is c1, the thickness of the second welding zone is c2, the area of ​​the first welding zone is C1, and the area of ​​the second welding zone is C2; wherein,

[0055] a, b1, b2, c1 satisfy c1 ≥ (a + b1 + b2) * 110%;

[0056] and / or, b1, b2, and c2 satisfy c2 ≥ (b1 + b2) * 110%;

[0057] And / or, c1, c2, C1, C2 satisfy c1*C1>c2*C2.

[0058] A battery cell comprises a first pole piece, a diaphragm and a second pole piece that are stacked and wound, wherein the polarity of the first pole piece and the second pole piece are opposite, the first pole piece is the pole piece in any of the above items, the current collector of the first pole piece is a first current collector, the pole tab of the first pole piece is a first pole tab, and the second pole piece includes a second current collector and a second pole tab.

[0059] Optionally, the number of the first tabs is n, and the number of the second tabs is m; wherein n and m satisfy:

[0060] n>m;

[0061] And / or, 2*m-1≤n≤2*m+1.

[0062] Optionally, the first pole lug includes a type 1 pole lug and a type 2 pole lug. In the MD direction of the first pole piece, the spacing distance between adjacent type 1 pole lugs and type 2 pole lugs is L1. In the MD direction of the second pole piece, the length of the second pole lug is L2, and L1 and L2 satisfy 1.2*L2<L1.

[0063] Optionally, the edge of the first current collector is located within the edge of the separator, and the separator completely covers the welding area of ​​the first electrode tab.

[0064] Optionally, in the winding direction of the battery core, the width of the battery core is A, the thickness of the battery core is B, the length of the connecting portion of the type 1 tab is S3, and the length of the connecting portion of the type 2 tab is S4; wherein,

[0065] S3 satisfies 5%*(A+B)≤S3≤60%*(A+B);

[0066] And / or, S4 satisfies 50%*(A+B)≤S4≤90%*(A+B).

[0067] A battery comprising a plurality of the battery cells according to any one of the above items, wherein between two adjacent battery cells, all the first tabs of each of the battery cells are pressed onto the first adapter plate, and all the second tabs of each of the battery cells are pressed onto the second adapter plate;

[0068] The first electrode tab and the first adapter plate are welded together, and weld marks are formed between the second electrode tab and the second adapter plate.

[0069] Optionally, the weld mark is completely located within the edge of the first pole lug or the second pole lug, and the distance between the edge of the weld mark and the outer edge of any side of the first pole lug or the second pole lug is greater than or equal to 0.5 mm and less than or equal to 5 mm.

[0070] Optionally, adhesive tape is pasted on the first electrode tab and the second electrode tab, and the adhesive tape completely covers all the weld marks.

[0071] The present application provides a pole piece comprising a current collector and a tab. The current collector comprises a support layer and a conductive layer, the conductive layer being located on at least one surface of the support layer. The tab comprises a main portion and a connecting portion adjacent to the main portion, the connecting portion being connected to the conductive layer. In the MD direction of the pole piece, the length of the connecting portion of the tab is greater than the length of the main portion of the tab, and the main portion extends away from the current collector. This configuration results in a special-shaped tab design. Based on a conventional tab, the tab is partially lengthened, resulting in the tab being divided into a main portion and a connecting portion. The main portion maintains its original dimensions, meeting the original design requirements and not affecting the tab's basic functionality. The relatively longer connecting portion is welded to the conductive layer of the current collector. This weld improves the current-carrying capacity of the resulting weld, reducing the charge and discharge temperature rise, thereby resolving the problem of insufficient current-carrying capacity at the tab weld in composite current collectors in the prior art, which can easily lead to temperature increases at the weld. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without any creative work.

[0073] FIG1 is a schematic diagram of the structure of a tab provided in an embodiment of the present application;

[0074] FIG2 is a schematic diagram of the structure of a pole piece provided in an embodiment of the present application;

[0075] FIG3 is a schematic diagram illustrating parameters of a type 1 tab and a type 2 tab provided in an embodiment of the present application;

[0076] FIG4 is a schematic diagram of the structure of the electrode tab and the current collector before welding according to an embodiment of the present application;

[0077] FIG5 is a schematic diagram of the structure of the electrode tab and the current collector after welding according to an embodiment of the present application;

[0078] FIG6 is a schematic diagram illustrating parameters of a welding mark area of ​​a tab provided in an embodiment of the present application;

[0079] FIG7 is a schematic diagram of the local positions of the ceramic portion and the tab according to an embodiment of the present application;

[0080] FIG8 is a schematic diagram illustrating parameters of a tab and a current collector provided in an embodiment of the present application;

[0081] FIG9 is a partial schematic diagram of the connection between the tab and the current collector provided in an embodiment of the present application;

[0082] FIG10 is a schematic cross-sectional view of a battery cell provided in an embodiment of the present application;

[0083] FIG11 is a schematic diagram of the relative positions of the first electrode tab and the second electrode tab provided in an embodiment of the present application;

[0084] FIG12 is a schematic diagram of the overall structure of a battery cell provided in an embodiment of the present application;

[0085] FIG13 is a schematic diagram of the electrical connection between two battery cells provided in an embodiment of the present application.

[0086] In Figures 1 to 13: 01, current collector; 02, tab; 11, support layer; 12, conductive layer; 13, coating portion; 14, ceramic portion; 15, empty current collector area; 21, type 1 tab; 22, type 2 tab; 201, main body; 202, connecting portion; 203, welding area; 211, first foil; 212, second foil; 2031, welding area 1; 2032, welding area 2; 1, first current collector; 2, first tab; 3, second current collector; 4, second tab; 5, diaphragm; 6, first adapter; 7, second adapter; 8, weld mark. DETAILED DESCRIPTION

[0087] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0088] As shown in Figures 1-9, embodiments of the present application provide a pole piece, which can be either a positive or negative pole piece, comprising a current collector 01 and a tab 02. The current collector 01 is a composite current collector comprising a support layer 11 and a conductive layer 12. The conductive layer 12 is located on at least one surface of the support layer 11. The tab 02 comprises a main portion 201 and a connecting portion 202 adjacent to the main portion 201. The main portion 201 extends away from the current collector 01. The main portion 201 and the connecting portion 202 are arranged along the TD direction of the pole piece. The connecting portion 202 is connected to the conductive layer 12 and electrically conductive therewith by welding. When the pole piece is unfolded, the length of the connecting portion 202 of the pole piece is greater than the length of the main portion 201 of the pole piece in the MD direction. It should be noted that the pole piece 02 is not a regular rectangle, but is often trapezoidal in shape. The length refers to the length at the longest point in the MD direction. Similarly, when describing the width, given that some parts may have irregular shapes, the width also refers to the width at the widest point in the TD direction.

[0089] With such a configuration, the pole tab 02 is of a special-shaped design. On the basis of the conventional pole tab 02, the pole tab 02 is partially lengthened so that the pole tab 02 is divided into a main body 201 and a connecting portion 202. The main body 201 still maintains the original specifications and dimensions, and still meets the original design requirements, without affecting the original basic functions of the pole tab 02. The connecting portion 202 with a relatively large length is welded to the conductive layer 12 of the current collector 01. The current-carrying capacity of the weld formed in this way is improved, which can reduce the charge and discharge temperature rise, and solves the problem in the prior art that the current-carrying capacity of the welding portion of the pole tab 02 of the composite current collector is insufficient, which easily leads to a temperature increase at the welding portion.

[0090] For example, conductive layers 12 are provided on both sides of the support layer 11. The conductive layers 12 are metal foils such as copper foil or aluminum foil. Generally, the surface of the conductive layer 12 is coated with an active material layer.

[0091] It should be noted that in this application, when the electrode is in the unfolded state, the MD direction of the electrode is the direction of larger size, that is, the length direction of the electrode; the TD direction of the electrode is the direction of smaller size, that is, the width direction of the electrode.

[0092] In another embodiment, a conductive layer 12 is provided on both side surfaces of the support layer 11, and a single pole tab 02 includes at least a first foil 211 and a second foil 212 respectively welded to the conductive layers 12 on both sides. In the TD direction of the pole piece, the width of the first foil 211 is greater than the width of the second foil 212, that is, the single pole tab 02 is formed by a wide foil and a narrow foil of different sizes, and at least a partial area of ​​the main body 201 is formed only by the first foil 211.

[0093] In this arrangement, due to the special structure of the composite current collector, two foils are required to be combined to form a single pole ear. The pole ear 02 provided in the present application has a single-layer foil area at the main body 201 located at the end. Therefore, while reducing the end thickness of the pole ear 02, in the subsequent welding process of the pole ear 02 and the adapter, each pole ear 02 is welded by a single-layer foil, which avoids the hidden danger of cold welding caused by too many foil pieces due to the existence of separate wide-width foils and narrow-width foils, and greatly reduces the difficulty of welding the pole ear 02 and the adapter.

[0094] Furthermore, the connecting portion 202 is formed by welding the first foil 211, the current collector 01 and the second foil 212; the connecting portion between the main body 201 and the connecting portion 202 is formed by welding the first foil 211, the current collector 01 and the second foil 212, and / or, by welding the first foil 211 and the second foil 212.

[0095] With this arrangement, the joint portion of the main body 201 and the connecting portion 202 is still formed by welding the wide foil and the narrow foil. On the one hand, the energy density is improved, and on the other hand, a sudden change from the large thickness of the connecting portion 202 to the small thickness of the main body 201 is avoided, that is, a sudden change from a large current overflow to a small current overflow is avoided, thereby avoiding the problem of reduced current flow capacity of the welding portion and a large amount of heat generated at the junction of the two foils.

[0096] In another embodiment, the tab 02 is provided with a plurality of tabs including a type-one tab 21 and a type-two tab 22. The plurality of type-one tabs 21 and the plurality of type-two tabs 22 are alternately distributed along the MD direction of the pole piece, and in the MD direction of the pole piece, the length of the main body 201 of the type-one tab 21 is S1, the length of the main body 201 of the type-two tab 22 is S2, the length of the connecting portion 202 of the type-one tab 21 is S3, and the length of the connecting portion 202 of the type-two tab 22 is S4; wherein, S 2>S1, that is, the length of the main portion 201 of the second-type tab 22 is greater than the length of the main portion 201 of the first-type tab 21, then the length of the connecting portion 202 of the second-type tab 22 must be greater than the length of the connecting portion 202 of the first-type tab 21; or, S2=S1, and S4>S3, that is, when the length of the main portion 201 of the second-type tab 22 is the same as that of the first-type tab 21, the length of the connecting portion 202 of the second-type tab 22 is greater than the length of the connecting portion 202 of the first-type tab 21.

[0097] In this arrangement, since the charge and discharge impedance of the composite current collector is larger than that of the conventional metal current collector, the positive electrode is usually the composite current collector and the negative electrode is the metal current collector, or the positive electrode is the metal collector and the negative electrode is the composite current collector. Taking the above-mentioned electrode sheet as the positive electrode sheet as an example, the current collector 01 of the negative electrode sheet will be set to a metal current collector, and the negative electrode ear 02 is cut and formed into one piece by the metal current collector. Therefore, the current carrying capacity of the negative electrode ear 02 is better than that of the positive electrode ear 02, and the number of the negative electrode ears 02 can maintain the original design. After the sheet and the negative electrode sheet are wound into a battery cell, because the positive electrode tab 02 is divided into two types, the negative electrode tab 02 and the type-one tab 21 of the positive electrode tab 02 are located on the same side, and the type-one tab 21 can avoid the tab 02 of the negative electrode sheet, while the type-two tab 22 is an additional structure, which is formed on the other side without the negative electrode tab 02, and there is no need to consider the avoidance factor. Therefore, the type-two tab 22 can have a design with a longer connecting portion 202, thereby further increasing the area of ​​the welding point and further improving the current-carrying capacity of the connection between the positive electrode tab 02 and the current collector 01.

[0098] In another embodiment, along the TD direction of the electrode sheet, the surface of the conductive layer 12 is sequentially provided with a coating portion 13, a ceramic portion 14, and an empty current collector region 15. The coating portion 13 is an active coating, also known as a paste. The connection portion 202 of the electrode tab 02 partially covers the ceramic portion 14, and the connection portion 202 of the electrode tab 02 is connected to the conductive layer 12 in the empty current collector region 15. It should be noted that the above content applies to both the type 1 electrode tab 21 and the type 2 electrode tab 22.

[0099] With such an arrangement, firstly, since the connection portion 202 of the pole tab 02 covers the local ceramic portion 14, while ensuring that the pole tab 02 does not contact the coating portion 13, it ensures that the pole tab 02 covers the entire area of ​​the empty collector area 15, thereby effectively ensuring the conductive performance of the pole piece; secondly, since the connection portion 202 of the pole tab 02 is supported by the ceramic portion 14, the thickness of the pole piece in this area is increased, which can reduce the possibility of the pole piece flipping; thirdly, after the pole tab 02 is welded to the collector 01, the whole needs to be die-cut to form a pole piece that meets the design requirements. Due to the arrangement of the ceramic portion 14, the cutting trajectory of the die-cutting will cut the ceramic portion 14, reducing the generation of burrs on the edge of the pole piece and improving safety performance.

[0100] Generally speaking, in a composite current collector, a conductive layer 12 is provided on both sides of the support layer 11. Since the conductive layers 12 on both sides cannot be directly conductive, a single pole tab 02 includes two layers of foil welded to the conductive layers 12 on both sides. On the one hand, the presence of the support layer 11 increases the difficulty of welding the pole tab 02 and the conductive layer 12 in the empty current collector area 15, and also increases the difficulty of welding the two layers of foil to conduction; on the other hand, since the support layer 11 is a polymer material layer, its own welding performance is poor, resulting in a relatively low welding strength between the pole tab 02 and the current collector 01 after welding.

[0101] To address the above issues, in another embodiment, conductive layers 12 are provided on both sides of the support layer 11. A single tab 02 comprises a first foil 211 and a second foil 212, which are connected to the current collector 01 via ultrasonic roll welding. On the current collector 01, the first and second foils 211, 212 are welded to the conductive layers 12 on either side, forming a three-layered weld zone 2031. Outside the current collector 01, the first and second foils 211, 212 are at least partially welded to form a two-layered weld zone 2032. The first and second weld zones 2031, 2032, are connected. This arrangement has been shown to increase the current conduction path, effectively reduce weld internal resistance, increase weld strength, and enhance the electrical performance of the battery cell. It should be noted that the above description applies to both Type I tabs 21 and Type II tabs 22.

[0102] In another embodiment, the first welding area 2031 and the second welding area 2032 are adjacently arranged.

[0103] With such an arrangement, on the one hand, since the welding zone 1 2031 and the welding zone 2 2032 are arranged adjacent to each other, the hidden danger of poor strength of the foil in the unwelded portion between the two welding zones due to the discontinuity of the welding zones, and the foil being easily damaged, thereby easily damaging the tab, is avoided. Moreover, the hidden danger of the tab being disconnected between the two welding zones due to the lack of pressure welding in the middle portion and pressure welding on both sides when the welding zones are arranged separately can be avoided. On the other hand, the welding zone 1 2031 and the welding zone 2 2032 are completed in the same process, which can reduce costs and improve production efficiency.

[0104] In another embodiment, at least the surface of the first welding area 2031 is coated with an insulating layer made of PET (polyethylene glycol terephthalate) or PP (polypropylene). This configuration can alleviate the problem of surface protrusions in the first welding area 2031, preventing the separator 5 between the positive and negative electrode sheets from being punctured, thereby preventing short circuits and battery cell safety issues.

[0105] In another embodiment, due to the welding of the tab 02 to the current collector 01, a welding region 203 is formed on the tab 02, including the aforementioned welding region 1 2031 and welding region 2032. In the TD direction of the electrode sheet, the width of the welding region 203 of the first type tab 21 is W1, and the width of the welding region 203 of the second type tab 22 is W2; wherein W1 satisfies 1mm≤W1≤10mm; and / or, W1 and W2 satisfy 0.5≤W1 / W2≤1.5. It should be noted that in W1 / W2, " / " is used to represent the ratio between W1 and W2, and the same applies to other relationship expressions in this application.

[0106] With such a configuration, on the one hand, it has been verified that the width of the welding area 203 of the tab 02 cannot be less than 1 mm. Such a welding area 203 is too narrow, resulting in the current capacity of the tab 02 being lower than the design requirement. The width of the welding area 203 of the tab 02 cannot be greater than 10 mm. Such a welding area 203 is too wide, which reduces the battery energy density. On the other hand, the width difference between the welding areas 203 of the type 1 tab 21 and the type 2 tab 22 cannot be too large. It has been verified that when the above ratio range is exceeded, the problem of uneven current distribution will occur.

[0107] In another embodiment, the length S1 of the main body 201 of the type-I tab 21 and the length S2 of the main body 201 of the type-II tab 22 further have the following relationship: S1 satisfies 4 mm ≤ S1 ≤ 50 mm; and / or, S2 satisfies 4 mm ≤ S2 ≤ 50 mm; and / or, S1 and S2 satisfy 0.5 ≤ S1 / S2 ≤ 1.

[0108] With such an arrangement, on the one hand, it has been verified that the length of the main body 201 of the pole tab 02 cannot be less than 4 mm. Such a pole tab 02 is too small and has insufficient current-carrying capacity. The length of the main body 201 of the pole tab 02 cannot be greater than 50 mm. Such a pole tab 02 is too large and is prone to folding when passing through the rollers of the battery cell winding equipment. On the other hand, in actual production, after the pole sheet is wound, the symmetrical center lines of each pole tab 02 are inevitably slightly misaligned. When the ratio of the length of the main body 201 of the type 1 pole tab 21 and the type 2 pole tab 22 meets the above range, even if there is a misalignment, it can be ensured that the overlapping area of ​​each pole tab 02 in the projection direction meets the design requirements.

[0109] In another embodiment, the length S3 of the connecting portion 202 of the first-type tab 21 and the length S4 of the connecting portion 202 of the second-type tab 22, under the premise of S3 / S4<1, further have the following relationship: S3 satisfies 6mm≤S3≤200mm; and / or, S4 satisfies 6mm≤S4≤300mm.

[0110] With such an arrangement, in a battery cell of common specifications, when the type 1 tab 21 and the type 2 tab 22 meet the above conditions, while ensuring that the tab 02 avoids contact with the pole piece of opposite polarity, the area of ​​the welding zone 203 between the tab 02 and the current collector 01 is maximized.

[0111] In another embodiment, the spacing distance between the first-type tab 21 and the second-type tab 22 in the MD direction of the electrode sheet is L1, and L1 satisfies 3mm≤L1≤100mm. It has been verified that in common battery cell specifications, selecting the spacing distance between the first-type tab 21 and the second-type tab 22 within this range for further design can result in a more reasonable battery cell design.

[0112] In another embodiment, in the TD direction of the electrode sheet, the height of the connection portion 202 of the first-type tab 21 is H1, and the height of the connection portion 202 of the second-type tab 22 is H2. The widths W1 and W2 of the welding area 203 of the first-type tab 21 and the welding area 203 of the second-type tab 22 further satisfy the following relationship: H1 and W1 satisfy 0.05≤H1 / W1≤0.95; and / or H2 and W2 satisfy 0.05≤H2 / W2≤0.95. It has been verified that selecting the length-to-height ratio parameters of the first-type tab 21 and the second-type tab 22 within this range for common battery cell specifications can result in a more reasonable battery cell design.

[0113] Furthermore, it is preferred that H1 and W1 satisfy 0.3≤H1 / W1≤0.6; and / or H2 and W2 satisfy 0.3≤H2 / W2≤0.6. This has been proven to yield a cell design with superior charge and discharge capabilities.

[0114] Regarding the design of the side of the pole piece where the pole piece tab 02 is located, it is also often called the pole piece head in this technical field. In another embodiment, the coating positions of the coating portion 13 and the ceramic portion 14 are certain. After the coating is completed, the pole piece 02 is welded. In the TD direction of the pole piece, the width of the ceramic portion 14 is Wt, and the width of the portion of the ceramic portion 14 covered by the pole piece 02 is Wf; wherein Wt satisfies 1mm≤Wt≤10mm; and / or, Wf satisfies 0<Wf≤5mm; Wt and Wf satisfy 0.1≤Wt / Wf≤0.9.

[0115] With such a setting, it has been verified that when Wt / Wf is less than 0.1, the coverage of the pole tab 02 on the ceramic part 14 is too low, and the pole tab 02 is likely to be unstable when overlapping the ceramic part 14, and the strength support provided by the ceramic part 14 to the pole tab 02 does not meet the design requirements. When Wt / Wf is greater than 0.9, the coverage of the pole tab 02 on the ceramic part 14 is too high and is relatively close to the coating part 13. Based on the existing situation that there are inevitable errors in the welding process, there is a possibility that the pole tab 02 contacts the coating part 13, which will cause the coating part 13 located at the head of the pole piece to be unable to be effectively utilized, and the battery energy density will be reduced.

[0116] In another embodiment, in the TD direction of the electrode, the width of the first welding area 2031 is d1, the width of the second welding area 2032 is d2, and the width of the welding area 203 formed by the first welding area 2031 and the second welding area 2032 is d; wherein d1 satisfies 0.5mm≤d1≤20mm; and / or, d2 satisfies 0.2mm≤d2≤10mm; and / or, d satisfies 2mm≤d≤50mm; and / or, d2 and d satisfy 0.1≤d2 / d≤0.7. With such a configuration, it has been verified that, in common battery cells, the tab 02 designed by selecting parameters within the above value ranges and ratios increases the current conduction path, effectively reduces the weld internal resistance, improves the weld strength, and enhances the electrical performance of the battery cell; the tab 02 designed with parameters below the above value ranges and ratios has poor electrical conductivity; and the tab 02 designed with parameters above the above value ranges and ratios results in a lower energy density of the battery cell.

[0117] In another embodiment, welding zone 1 2031 and welding zone 2 2032 form a welding zone 203, and in the TD direction of the pole piece, the distance between the outer edge of the connecting portion 202 of the pole tab 02 and the inner edge of the welding zone 203 is D1, and the distance between the outer edge of the connecting portion 202 of the pole tab 02 and the outer edge of the welding zone 203 is D2; wherein, D1 satisfies 0.5mm≤D1≤20mm; and / or, 0.5mm≤D2≤20mm; and / or, D1 and D2 satisfy 0.1≤D1 / D2≤0.7. With such a setting, it has been verified that, in battery cells of common specifications, the tab 02 designed by selecting parameters within the above-mentioned value range and ratio range can effectively improve the situation where the tab 02 is easy to fold, and reduce the battery cell safety problems caused by short circuits; if the tab 02 is designed with parameters lower than the above-mentioned value range and ratio range, the tab 02 is easy to fold and the conductivity of the tab 02 is poor; if the tab 02 is designed with parameters higher than the above-mentioned value range and ratio range, the energy density of the battery cell will be low.

[0118] In another embodiment, the connection between the connecting portion 202 of the tab 02 and the current collector 01 is an arc with a radius of R1, the connection between the main portion 201 of the tab 02 and the connecting portion 202 is an arc with a radius of R2, and the outer edge angle of the connecting portion 202 of the tab 02 is an arc with a radius of R3; wherein R1 satisfies 0.5mm≤R1≤10mm; and / or, R2 satisfies 0.5mm≤R2≤10mm; and / or, R3 satisfies 0.2mm≤R3≤5mm. With such a setting, it has been verified that, in battery cells of common specifications, the tab 02 designed by selecting parameters within the above value range effectively improves the problem of the tab 02 being easily folded, reducing battery cell safety issues caused by short circuits; when parameters are selected outside the above value range, the problem of the tab 02 being easily folded is not well improved.

[0119] In another embodiment, in the TD direction of the electrode sheet, the width of the current collector 01 is D3, and the height of the connection portion 202 of the tab 02 is D4, where D3 and D4 satisfy 0.1≤D4 / D3≤0.5. With this arrangement, it has been verified that, in commonly used battery cells, the tab 02 designed with parameters within the aforementioned ratio range can provide sufficient area for the formation of the welding area 203, thereby improving the current conduction path, effectively reducing the internal resistance of the weld, increasing the weld strength, and enhancing the electrical performance of the battery cell. Tabs designed with parameters below the aforementioned ratio range may have poor electrical conductivity. Tabs designed with parameters above the aforementioned ratio range may result in a lower energy density in the battery cell.

[0120] In another embodiment, the thickness of the current collector 01 is a, the thickness of the first foil 211 is b1, the thickness of the second foil 212 is b2, the thickness of the first welding area 2031 is c1, the thickness of the second welding area 2032 is c2, the area of ​​the first welding area 2031 is C1, and the area of ​​the second welding area 2032 is C2; wherein, a, b1, b2, and c1 satisfy c1≥a+b1+b2*110%; and / or, b1, b2, and c2 satisfy c2≥b1+b2*110%; and / or, c1, c2, C1, and C2 satisfy c1*C1>c2*C2. With such a setting, it has been verified that, in battery cells of common specifications, if the selected parameters meet the above conditions, the designed electrode can significantly reduce the charge and discharge current density of welding area 1 2031 and welding area 2032, and prevent local temperature rise too quickly during charging and discharging; if the selected parameters do not meet the above conditions, the thickness of welding area 1 2031 and welding area 2032 is too small, and it cannot ensure that the problem of high charge and discharge current density in welding area 1 2031 and welding area 2032 is improved.

[0121] Based on the above-mentioned electrode pieces, an embodiment of the present application also provides a battery cell, as shown in Figures 10 to 13, the battery cell includes a first electrode piece, a diaphragm 5 and a second electrode piece that are stacked and wound. The polarity of the first electrode piece is opposite to that of the second electrode piece. The first electrode piece is the above-mentioned electrode piece, the current collector 01 of the first electrode piece is the first current collector 1, the electrode tab 02 of the first electrode piece is the first electrode tab 2, and the second electrode piece includes a second current collector 3 and a second electrode tab 4. Since the battery cell has the above-mentioned electrode pieces, the beneficial effects of the electrode pieces on the battery cell can be found in the above content and will not be repeated here. For example, the first electrode piece is a positive electrode piece, the second electrode piece is a negative electrode piece, the second current collector 3 is a metal current collector, and the second electrode tab 4 is formed as a whole by cutting the metal current collector.

[0122] In another embodiment, the number of the first electrode tabs 2 is n, and the number of the second electrode tabs 4 is m; wherein n and m satisfy: n>m; and / or, 2*m-1≤n≤2*m+1.

[0123] In this way, along the winding direction of the battery cell, a first pole tab 2 is provided for every half turn on the first pole sheet, and a second pole tab 4 is provided for every turn on the second pole sheet. The number of first pole tabs 2 is increased on the first pole sheet, thereby compensating for the lack of charge and discharge performance of the first current collector 1 which is a composite current collector. The second current collector 3 of the second pole sheet is a metal current collector. The current carrying capacity of the second pole tab 4 obtained by cutting and integrally forming is better than that of the first pole tab 2. There is no need for too many second pole tabs 4 and the original number can be maintained. After winding is completed, all the first pole tabs 2 are opposite to each other, and all the second pole tabs 4 are opposite to each other.

[0124] In another embodiment, the first pole tab 2 includes a type-I pole tab 21 and a type-II pole tab 22, and the type-I pole tab 21 and the type-II pole tab 22 are alternately arranged along the winding direction of the battery cell. In the MD direction of the first pole sheet, the spacing distance between adjacent type-I pole tabs 21 and type-II pole tabs 22 is L1, and in the MD direction of the second pole sheet, the length of the second pole tab 4 is L2, and L1 and L2 satisfy 1.2*L2<L1.

[0125] With this arrangement, after the first and second pole pieces are stacked, in the MD direction of the pole pieces, the second pole tab 4 is located between two adjacent first pole tabs 2 and is designed to be 1.2*L2<L1, which can prevent the first pole tab 2 and the second pole tab 4 of opposite polarity from contacting each other.

[0126] In another embodiment, the edge of the first current collector 1 is located within the edge of the separator 5, and the separator 5 completely covers the welding area 203 of the first electrode tab 2. Generally speaking, in the TD direction of the electrode sheet, the edge of the separator 5 extends beyond the edges of the first current collector 1 and the second current collector 3. This arrangement ensures that when all the first electrode tabs 2 are assembled and slightly bent, the welding area 203 between the first electrode tab 2 and the first current collector 1 will not contact the second current collector 3 and short-circuit.

[0127] In another embodiment, in the winding direction of the battery cell, the width of the battery cell is A, the thickness of the battery cell is B, the length of the connecting portion 202 of the type-1 tab 21 is S3, and the length of the connecting portion 202 of the type-2 tab 22 is S4; wherein, S3 satisfies 5%*(A+B)≤S3≤60%*A+B; and / or, S4 satisfies 50%*(A+B)≤S4≤90%*A+B.

[0128] In this way, when the type 1 tab 21 and the type 2 tab 22 meet the above conditions, it can ensure that the welding space is maximized and the area of ​​the welding area 203 between the first tab 2 and the first current collector 1 is increased as much as possible. At the same time, it can ensure that after the battery cell is placed in the shell, the first tab 2 does not interfere with the battery shell and cause safety risks.

[0129] As can be seen, after the battery cell is wound, all tabs 02 need to be connected to external electrical devices through a switching method. In actual battery production, batteries are generally composed of one or more battery cells to meet design requirements.

[0130] Based on the above-described battery cell, an embodiment of the present application further provides a battery comprising a plurality of the above-described battery cells. Between two adjacent battery cells, all first tabs 2 of each battery cell are pressed onto a first adapter plate 6, and all second tabs 4 of each battery cell are pressed onto a second adapter plate 7. The first tabs 2 and the first adapter plate 6, as well as the second tabs 4 and the second adapter plate 7, are welded to form weld marks 8; that is, four weld marks 8 are formed between the two battery cells. Since this battery comprises the above-described battery cells, the beneficial effects of the battery cells are described above and will not be elaborated upon here.

[0131] In another embodiment, the weld mark 8 is completely located within the edge of the first pole tab 2 or the second pole tab 4, and the distance between the edge of the weld mark 8 and the outer edge of either side of the first pole tab 2 or the second pole tab 4 is greater than or equal to 0.5 mm and less than or equal to 5 mm.

[0132] With this arrangement, a distance of at least 0.5 mm is left between the weld mark 8 and the tab 02, which can accommodate the position deviation that may be caused by the welding process and prevent welding to positions other than the tab 02; and the distance between the weld mark 8 and the tab 02 is controlled to be no greater than 5 mm in order to ensure that there is sufficient welding area between the tab 02 and the adapter.

[0133] In another embodiment, adhesive tape is affixed to the first tab 2 and the second tab 4, the adhesive tape completely covering all weld marks 8, and the adhesive tape partially or completely covering the first tab 2 and the second tab 4. In this arrangement, when the two battery cells are adjusted to be positioned side by side, the adhesive tape prevents the uneven surface of the weld marks 8 from damaging the battery cell structure.

[0134] The basic principles of the present application have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in this application are merely illustrative and not restrictive, and it should not be assumed that these advantages, strengths, and effects are required of each embodiment of this application. In addition, the specific details disclosed above are merely illustrative and facilitating understanding, and are not restrictive. The above details do not limit this application to necessarily being implemented using the above specific details.

[0135] The block diagrams of the devices, devices, equipment, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, devices, equipment, and systems can be connected, arranged, or configured in any manner. Words such as "include," "comprise," "have," and the like are open-ended words, meaning "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or" and can be used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

[0136] It should also be noted that in the apparatus, device, and method of the present application, each component or each step can be decomposed and / or recombined, and such decomposition and / or recombination should be regarded as equivalent solutions of the present application.

[0137] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0138] It should be understood that the qualifiers "first", "second", "third", "fourth", "fifth" and "sixth" used in the description of the embodiments of the present application are only used to more clearly illustrate the technical solutions and cannot be used to limit the scope of protection of the present application.

[0139] The above description has been provided for the purpose of illustration and description. Furthermore, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A pole piece, characterized in that, it includes: a current collector (01), including a support layer (11) and a conductive layer (12), and the conductive layer (12) is at least located on one side surface of the support layer (11); a tab (02), including a main body portion (201) and a connecting portion (202) adjacent to the main body portion (201), the connecting portion (202) is connected to the conductive layer (12), and the main body portion (201) extends in a direction away from the current collector (01); wherein, in the MD direction of the pole piece, the length of the connecting portion (202) of the tab (02) is greater than the length of the main body portion (201) of the tab (02).

2. The pole piece according to claim 1, characterized in that, the conductive layers (12) are provided on both side surfaces of the support layer (11), and a single tab (02) at least includes a first foil (211) and a second foil (212) respectively connected to the conductive layers (12) on both sides. In the TD direction of the pole piece, the width of the first foil (211) is greater than the width of the second foil (212), and at least a part of the main body portion (201) is formed only by the first foil (211).

3. The pole piece according to claim 2, characterized in that, the connecting portion (202) is formed by welding the first foil (211), the current collector (01) and the second foil (212); at the joint portion of the main body portion (201) and the connecting portion (202), it is formed by welding the first foil (211), the current collector (01) and the second foil (212), and / or is formed by welding the first foil (211) and the second foil (212).

4. The pole piece according to any one of claims 1-3, characterized in that, a plurality of tabs (02) are provided and include type-I tabs (21) and type-II tabs (22). A plurality of the type-I tabs (21) and a plurality of the type-II tabs (22) are alternately distributed along the MD direction of the pole piece. In the MD direction of the pole piece, the length of the main body portion (201) of the type-I tab (21) is S1, the length of the main body portion (201) of the type-II tab (22) is S2, the length of the connecting portion (202) of the type-I tab (21) is S3, and the length of the connecting portion (202) of the type-II tab (22) is S4; wherein, S2 > S1; or, S2 = S1, and S4 > S3.

5. The pole piece according to any one of claims 1-4, characterized in that, along the TD direction of the pole piece, a coating portion (13), a ceramic portion (14) and an empty current collector area (15) are sequentially provided on the surface of the conductive layer (12). The connecting portion (202) of the tab (02) covers a part of the ceramic portion (14), and the connecting portion (202) of the tab (02) is connected to the conductive layer (12) in the empty current collector area (15).

6. The pole piece according to any one of claims 1-5, It is characterized in that the conductive layers (12) are provided on both side surfaces of the support layer (11), and a single tab (02) includes a first foil (211) and a second foil (212); wherein on the current collector (01), the first foil (211) and the second foil (212) are respectively welded to the conductive layers (12) on both sides, and the first foil (211), the current collector (01) and the second foil (212) form a welding zone one (2031); outside the current collector (01), the first foil (211) and the second foil (212) are at least partially welded to form a welding zone two (2032).

7. The electrode tab according to claim 6, It is characterized in that at least the surface of the welding zone one (2031) is provided with an insulating layer, and the welding zone one (2031) and the welding zone two (2032) are arranged adjacent to each other.

8. The electrode tab according to any one of claims 4-7, It is characterized in that the tab (02) is welded to the current collector (01), and a welding zone (203) is formed on the tab (02). In the TD direction of the electrode tab, the width of the welding zone (203) of the type-one tab (21) is W1, and the width of the welding zone (203) of the type-two tab (22) is W2; wherein W1 satisfies 1mm ≤ W1 ≤ 10mm; and / or, W1 and W2 satisfy 0.5 ≤ W1 / W2 ≤ 1.

5.

9. The electrode tab according to any one of claims 4-8, It is characterized in that S1 satisfies 4mm ≤ S1 ≤ 50mm; and / or, S2 satisfies 4mm ≤ S2 ≤ 50mm; and / or, S1 and S2 satisfy 0.5 ≤ S1 / S2 ≤ 1.

10. The electrode tab according to any one of claims 4-9, It is characterized in that S3 satisfies 6mm ≤ S3 ≤ 200mm; and / or, S4 satisfies 6mm ≤ S4 ≤ 300mm.

11. The electrode tab according to any one of claims 4-10, It is characterized in that in the MD direction of the electrode tab, the spacing distance between the type-one tab (21) and the type-two tab (22) is L1, and L1 satisfies 3mm ≤ L1 ≤ 100mm.

12. The electrode tab according to any one of claims 8-11, It is characterized in that in the TD direction of the electrode tab, the height of the connecting portion (202) of the type-one tab (21) is H1, and the height of the connecting portion (202) of the type-two tab (22) is H2; wherein H1 and W1 satisfy 0.05 ≤ H1 / W1 ≤ 0.95; and / or, H2 and W2 satisfy 0.05 ≤ H2 / W2 ≤ 0.

95.

13. The electrode tab according to claim 12, It is characterized in that H1 and W1 satisfy 0.3 ≤ H1 / W1 ≤ 0.6; and / or, H2 and W2 satisfy 0.3 ≤ H2 / W2 ≤ 0.

6.

14. The electrode tab according to any one of claims 5-13, It is characterized in that In the TD direction of the electrode tab, the width of the ceramic part (14) is Wt, and the width of the part of the ceramic part (14) covered by the tab (02) is Wf; wherein, Wt satisfies 1 mm ≤ Wt ≤ 10 mm; and / or, Wf satisfies 0 < Wf ≤ 5 mm; and / or, Wt and Wf satisfy 0.1 ≤ Wf / Wt ≤ 0.

9.

15. The electrode tab according to any one of claims 6-14, characterized in that in the TD direction of the electrode tab, the width of the first welding area (2031) is d1, the width of the second welding area (2032) is d2, and the width of the welding area (203) formed by the first welding area (2031) and the second welding area (2032) is d; wherein, d1 satisfies 0.5 mm ≤ d1 ≤ 20 mm; and / or, d2 satisfies 0.2 mm ≤ d2 ≤ 10 mm; and / or, d satisfies 2 mm ≤ d ≤ 50 mm; and / or, d2 and d satisfy 0.1 ≤ d2 / d ≤ 0.

7.

16. The electrode tab according to any one of claims 6-15, characterized in that the first welding area (2031) and the second welding area (2032) form a welding area (203). In the TD direction of the electrode tab, the distance between the outer edge of the connecting part (202) of the tab (02) and the inner edge of the welding area (203) is D1, and the distance between the outer edge of the connecting part (202) of the tab (02) and the outer edge of the welding area (203) is D2; wherein, D1 satisfies 0.5 mm ≤ D1 ≤ 20 mm; and / or, 0.5 mm ≤ D2 ≤ 20 mm; and / or, D1 and D2 satisfy 0.1 ≤ D1 / D2 ≤ 0.

7.

17. The electrode tab according to any one of claims 1-16, characterized in that the connection between the connecting part (202) of the tab (02) and the current collector (01) is an arc with a radius of R1, the connection between the main body part (201) of the tab (02) and the connecting part (202) is an arc with a radius of R2, and the outer edge angle of the connecting part (202) of the tab (02) is an arc with a radius of R3; wherein, R1 satisfies 0.5 mm ≤ R1 ≤ 10 mm; and / or, R2 satisfies 0.5 mm ≤ R2 ≤ 10 mm; and / or, R3 satisfies 0.2 mm ≤ R3 ≤ 5 mm.

18. The electrode tab according to any one of claims 1-17, characterized in that in the TD direction of the electrode tab, the width of the current collector (01) is D3, and the height of the connecting part (202) of the tab (02) is D4. D3 and D4 satisfy 0.1 ≤ D4 / D3 ≤ 0.

5.

19. The electrode tab according to any one of claims 6-18, characterized in that The thickness of the current collector (01) is a, the thickness of the first foil (211) is b1, the thickness of the second foil (212) is b2, the thickness of the first welding area (2031) is c1, the thickness of the second welding area (2032) is c2, the area of the first welding area (2031) is C1, and the area of the second welding area (2032) is C2; where a, b1, b2, c1 satisfy c1 ≥ (a + b1 + b2) * 110%; and / or, b1, b2, c2 satisfy c2 ≥ (b1 + b2) * 110%; and / or, c1, c2, C1, C2 satisfy c1 * C1 > c2 * C2.

20. A battery cell characterized in that it includes a first electrode tab, a separator (5), and a second electrode tab that are stacked and wound, the first electrode tab and the second electrode tab have opposite polarities, the first electrode tab is the electrode tab according to any one of claims 1-19, the current collector (01) of the first electrode tab is a first current collector (1), the electrode ear (02) of the first electrode tab is a first electrode ear (2), and the second electrode tab includes a second current collector (3) and a second electrode ear (4).

21. The battery cell according to claim 20 characterized in that the number of the first electrode ears (2) is n, and the number of the second electrode ears (4) is m; where n, m satisfy: n > m; and / or, 2 * m - 1 ≤ n ≤ 2 * m + 1.

22. The battery cell according to claim 20 or 21 characterized in that the first electrode ear (2) includes a type-one electrode ear (21) and a type-two electrode ear (22), in the MD direction of the first electrode tab, the spacing distance between adjacent type-one electrode ear (21) and type-two electrode ear (22) is L1, in the MD direction of the second electrode tab, the length of the second electrode ear (4) is L2, and L1, L2 satisfy 1.2 * L2 < L1.

23. The battery cell according to any one of claims 20-22 characterized in that the edge of the first current collector (1) is located within the edge of the separator (5), and the separator (5) completely covers the welding area (203) of the first electrode ear (2).

24. The battery cell according to any one of claims 22 or 23 characterized in that in the winding direction of the battery cell, the width of the battery cell is A, the thickness of the battery cell is B, the length of the connecting portion (202) of the type-one electrode ear (21) is S3, and the length of the connecting portion (202) of the type-two electrode ear (22) is S4; where S3 satisfies 5% * (A + B) ≤ S3 ≤ 60% * (A + B); and / or, S4 satisfies 50% * (A + B) ≤ S4 ≤ 90% * (A + B).

25. A battery characterized in that it includes a plurality of battery cells according to any one of claims 20-24, between two adjacent battery cells, all the first electrode ears (2) of each battery cell are pressed onto a first adapter plate (6), and all the second electrode ears (4) of each battery cell are pressed onto a second adapter plate (7); Between the first tab (2) and the first adapter piece (6), and between the second tab (4) and the second adapter piece (7), welding is performed to form welding imprints (8).

26. The battery according to claim 25, characterized in that the welding imprints (8) are completely located within the edges of the first tab (2) or the second tab (4), and the distance between the edge of the welding imprint (8) and any outer edge of the first tab (2) or the second tab (4) is greater than or equal to 0.5 mm and less than or equal to 5 mm.

27. The battery according to claim 25 or 26, characterized in that adhesive tapes are pasted on the first tab (2) and the second tab (4), and the adhesive tapes completely cover all the welding imprints (8). ​

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