Battery

Abstract

The present disclosure provides a battery. The battery comprises a first electrode sheet unit; the first electrode sheet unit comprises a first current collector, a first active material layer, first tabs, and first notches; the first tabs are connected to the first current collector; at least two first notches overlap in the thickness direction of the first current collector to form a first accommodating groove; at least two first tabs are connected to each other to form a first tab group; the first tab group is located in the first accommodating groove. The first electrode sheet unit has a first surface and a second surface which are opposite to each other; the first active material layer comprises a first active coating and a second active coating; the first active coating is arranged on the first surface, and the second active coating is arranged on the second surface; the side of the first active coating close to the first tabs is provided with a first side edge, the side of the second active coating close to the first tabs is provided with a second side edge, and the first side edge and the second side edge are staggered in a first direction. The battery of the present disclosure has high energy density and the cleaning effect of the first electrode sheet unit is good.

Description

Battery TECHNICAL FIELD

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

[0002] At present, people have higher and higher requirements for the endurance time of electrical devices, so high energy density is still one of the main development directions of lithium ion batteries.

[0003] In the related art, a lithium ion battery mainly includes a battery shell and a battery cell, the battery cell and an electrolyte are packaged in the battery shell, the battery cell can include a positive electrode sheet, a separator and a negative electrode sheet, the positive electrode sheet, the separator and the negative electrode sheet are sequentially laminated and then wound or laminated, the positive electrode sheet and the negative electrode sheet can each include a foil and an active material coated on the surface of the foil, during coating, a part of the foil is reserved as an empty foil area on one side in the length direction of the electrode sheet, then part of the active material is cleaned, and then die cutting is performed, so that the foil can form a current collector and a foil tab, the active material covers the current collector, and after the plurality of foil tabs are bent and welded, a tab group is formed, the tab group is connected to an external device through a switching tab, so as to lead out the current of the battery cell.

[0004] Since the tab group needs to occupy part of the space inside the battery shell, the volume of the battery is increased, and the energy density of the battery is reduced. SUMMARY

[0005] Therefore, the present disclosure provides a battery, which can solve the problem that the tab group occupies part of the space inside the battery shell, so that the volume of the battery is increased and the energy density is reduced.

[0006] The battery provided by the embodiments of the present disclosure includes a first electrode sheet unit and a second electrode sheet unit with opposite polarities, the first electrode sheet unit and the second electrode sheet unit are laminated to form a battery cell, the first electrode sheet unit includes a first current collector, a first active material layer, a plurality of first tabs and a plurality of first notches, the second electrode sheet unit includes a plurality of second tabs, the first tabs are connected to the first current collector, the plurality of first notches overlap to form a first receiving groove in the thickness direction of the first current collector, the plurality of first tabs are connected to each other to form a first tab group, and the first tab group is at least partially located in the first receiving groove.

[0007] The first electrode sheet unit has opposite first and second surfaces, the first active material layer includes a first active coating layer and a second active coating layer, the first active coating layer is arranged on the first surface, and the second active coating layer is arranged on the second surface.

[0008] The side of the first active coating close to the first tab has a first side edge, and the side of the second active coating close to the first tab has a second side edge, both of which extend along the second direction, and the first side edge is arranged staggered with the second side edge along the first direction.

[0009] The battery provided by the present disclosure comprises a first tab unit, the first tab unit comprises a first current collector, a first active material layer, a first tab and a first notch, the first active material layer comprises a first active coating and a second active coating, the first active coating comprises a first side edge, and the second active coating comprises a second side edge. The first active material layer is arranged to react with the electrolyte to generate an electric current, the first current collector is arranged to collect the electric current generated by the first active material layer, the first tab is arranged to lead out the electric current of the first current collector, at least two first tabs are connected to each other to form a first tab group to improve the charge and discharge efficiency of the battery, and the first notch is arranged to overlap to form a first receiving groove along the thickness direction of the first current collector after the first tab unit is wound or stacked, and then the first tab group is received in the first receiving groove to avoid the first tab group increasing the dead volume of the battery, thereby improving the energy density of the battery. The first side edge and the second side edge are arranged staggered along the first direction, thereby ensuring the cleaning effect and preventing the first current collector from being damaged during cleaning.

[0010] In addition to the technical problems solved by the above-described embodiments of the present disclosure, the technical features constituting the technical solutions and the beneficial effects brought by these technical features, other technical problems solved by the battery provided by the present disclosure, other technical features included in the technical solutions and the beneficial effects brought by these technical features will be further described in detail in the specific embodiments.

[0011] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as exactly that endpoint or either exact value within a range unless expressly indicated otherwise. For values that are presented as a range, the endpoints of the range and individual points within the range can be combined with other endpoint values or individual point values to create one or more new ranges within or outside of the presented ranges. Such new ranges are to be considered as disclosed herein. BRIEF DESCRIPTION OF DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, a brief introduction will be given below to the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present disclosure, and other drawings can also be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0013] FIG. 1 is a structural schematic diagram of a battery provided by an embodiment of the present disclosure;

[0014] Fig. 2 is a structural schematic diagram of a first pole piece unit in a battery according to an embodiment of the present disclosure;

[0015] Fig. 3 is a cross-sectional view of A-A in Fig. 2;

[0016] Fig. 4 is a structural schematic diagram of a first surface of a first pole piece unit in a battery according to an embodiment of the present disclosure;

[0017] Fig. 5 is a structural schematic diagram of a second surface of a first pole piece unit in a battery according to an embodiment of the present disclosure;

[0018] Fig. 6 is a structural schematic diagram of a first current collector and a first tab in a battery according to an embodiment of the present disclosure;

[0019] Fig. 7 is a structural schematic diagram of a second pole piece unit in a battery according to an embodiment of the present disclosure;

[0020] Fig. 8 is a structural schematic diagram of a first pole piece unit and a second pole piece unit in a battery according to an embodiment of the present disclosure.

[0021] Legend of reference numerals: 100 - first pole piece unit; 100a - first surface; 100b - second surface; 110 - first current collector; 120 - first active material layer; 121 - first active coating layer; 1211 - first side edge; 122 - second active coating layer; 1221 - second side edge; 1222 - first coating area; 1223 - second coating area; 130 - first tab; 140 - first notch; 150 - insulation layer; 151 - first insulation coating layer; 1511 - first area; 1512 - second area; 152 - second insulation coating layer; 160 - second notch; 200 - first receiving groove; 300 - second pole piece unit; 310 - second current collector; 320 - second active material layer; 321 - third side edge; 330 - third notch; 340 - second tab; 350 - fourth notch. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be described in more detail below with reference to the drawings in the preferred embodiments of the present disclosure. In the drawings, the same or similar reference numerals represent the same or similar components or components with the same or similar functions throughout. The described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present disclosure, and cannot be understood as a limitation of the present disclosure. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present disclosure. The embodiments of the present disclosure will be described in detail below with reference to the drawings.

[0023] In the description of the disclosure, it should be explained that, unless otherwise explicitly specified and limited, the terms “mount”, “connect”, “connection” should be understood in a broad sense, for example, it can be fixed connection, or indirect connection through intermediate medium, or internal communication of two elements, or interaction relationship of two elements. For those skilled in the art, the specific meaning of the above terms in the disclosure can be understood according to the specific circumstances.

[0024] In the description of the disclosure, it should be understood that the terms “upper”, “lower”, “front”, “rear”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer” and the like indicate the orientation or positional relationship based on the drawings, and are only for the convenience of describing the disclosure and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the disclosure.

[0025] The terms “first”, “second”, “third” (if any) in the description and claims of the disclosure and the above drawings are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the disclosure described herein can be implemented in an order other than that illustrated or described herein.

[0026] In addition, the terms “include” and “have” and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or display including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or displays.

[0027] In the related art, the lithium ion battery mainly includes a battery shell and a battery cell, the battery cell and electrolyte are packaged in the battery shell, the battery cell can include a positive plate, a separator and a negative plate, the positive plate, the separator and the negative plate are sequentially laminated and then wound or laminated, the positive plate and the negative plate can each include a foil and an active material coated on the surface of the foil, during coating, a part of the foil area is reserved on one side of the length direction of the plate, then part of the active material is cleaned, and then die cutting is performed, so that the foil can form a current collector and a foil tab, the active material covers the current collector, and after bending and welding connection of the plurality of foil tabs, a tab group can be formed, the tab group is connected with an external device through a switching tab, so as to lead out the current of the battery cell.

[0028] Since the tab group needs to occupy part of the space inside the battery shell, the effective volume of the battery is increased, thereby reducing the energy density of the battery.

[0029] In view of the above problems, the battery provided by the embodiments of the present disclosure is configured to set a first notch in a first tab unit, so that after the first tab unit is wound or laminated to form a battery cell, at least two first notches overlap in the thickness direction of the battery cell, thereby forming a first accommodation groove, and the first lug group can be accommodated in the first accommodation groove, thereby avoiding the increase of the invalid volume of the battery caused by the first lug group, and improving the energy density of the battery. At the same time, the first tab unit is arranged with the first active material layer on the opposite sides of the first lug in a staggered manner, thereby ensuring that the active material of the first active material layer is cleaned in place and preventing the first current collector from being damaged during cleaning.

[0030] The specific embodiments of the battery provided by the embodiments of the present disclosure will be described in detail below with reference to FIGS. 1 to 8.

[0031] Referring to FIGS. 1 to 6, the battery provided by the embodiments of the present disclosure includes a first tab unit 100, the first tab unit 100 includes a first current collector 110, a first active material layer 120, a first lug 130, and a first notch 140, the first lug 130 is connected to the first current collector 110, at least two first notches 140 overlap in the thickness direction of the first current collector 110 to form a first accommodation groove 200, at least two first lugs 130 are connected to each other to form a first lug group, and the first lug group is at least partially located in the first accommodation groove 200.

[0032] The first tab unit 100 has opposite first and second surfaces 100a and 100b, the first active material layer 120 includes a first active coating layer 121 and a second active coating layer 122, the first active coating layer 121 is arranged on the first surface 100a, and the second active coating layer 122 is arranged on the second surface 100b.

[0033] In the first direction, the side of the first active coating layer 121 close to the first lug 130 has a first side edge 1211, and the side of the second active coating layer 122 close to the first lug 130 has a second side edge 1221, the first side edge 1211 and the second side edge 1221 both extend in the second direction, and the first side edge 1211 and the second side edge 1221 are arranged in a staggered manner in the first direction.

[0034] The first direction can refer to the X direction in FIGS. 4 and 5, and the second direction can refer to the Y direction in FIGS. 4 and 5. In the present disclosure, the X direction is the width direction of the first tab unit, i.e., the extension direction of the lug, and the Y direction is the length direction of the first tab unit.

[0035] It should be noted that the battery can further include a second tab unit 300 and a separator, the polarities of the first tab unit 100 and the second tab unit 300 are opposite, and the first tab unit 100, the separator and the second tab unit 300 are sequentially stacked and then wound to form a wound type battery cell, or the first tab unit 100, the separator and the second tab unit 300 are sequentially stacked and then stacked to form a stacked type battery cell, regardless of the wound type battery cell or the stacked type battery cell, the battery cell has at least two folds or layers.

[0036] The first tab unit 100 can include a first current collector 110, a first active material layer 120, a first tab 130 and a first notch 140, for the convenience of explanation, the polarity of the first tab unit 100 is taken as a positive electrode, and the structure of the first tab unit 100 is described in combination with the process flow of the first tab unit 100.

[0037] The process flow of the first tab unit 100 mainly includes coating, cleaning and die cutting, etc. First, the first active material is coated on the aluminum foil along the length direction of the aluminum foil to form the first active material layer 120, and at the same time, a part of the region on one side of the aluminum foil in the length direction is reserved not to be coated with the first active material, that is, a first empty foil area. Then, the preset area where the first active material layer 120 has been coated is cleaned to clean the first active material in the preset area, thereby forming a second empty foil area, and the first empty foil area and the second empty foil area together form an empty foil area. Then, the empty foil area is die cut, so that the aluminum foil forms the first current collector 110 and the first tab 130, respectively, and after die cutting, the first notch 140 can be formed on the first tab unit 100.

[0038] Then, the first tab unit 100 can be wound to form a wound type battery cell, and the battery cell can have a plurality of folds, a part of the folds can have the first tab 130, and the other part of the folds can not have the first tab 130. The first notch 140 and the first tab 130 are arranged one by one, a plurality of first tabs 130 are bent and welded to form a first tab group, and at the same time, the first notches 140 of each fold are overlapped to form a first receiving groove 200. The first tab group can be received in the first receiving groove 200, which can avoid the first tab group increasing the invalid volume of the battery, thereby effectively improving the energy density of the battery.

[0039] Alternatively, the first tab unit 100 can be stacked to form a stacked battery cell. The battery cell can have a plurality of layers, each of which can have the first tab 130, the first notch 140, and the first tab 130 arranged one-to-one. The plurality of first tabs 130 can be welded after being bent to form a first tab group. Meanwhile, the first notches 140 of each layer are overlapped to form a first receiving groove 200. The first tab group can be received in the first receiving groove 200. In this way, the first tab group can avoid increasing the dead volume of the battery, thereby effectively improving the energy density of the battery.

[0040] It should be understood that during cleaning, the cleaning tool can adopt a scraper that is scraped from outside to inside along the width direction of the first current collector 110 to clean the first surface 100a of the first tab unit 100 first and then clean the second surface 100b of the first tab unit 100. In order to ensure the cleaning effect and prevent the first current collector 110 from being damaged during cleaning, the first active coating 121 of the first surface 100a and the second active coating 122 of the second surface 100b can be cleaned in a staggered manner. When the scraper is cleaned on the first surface 100a, it will continue to move in the direction of the first current collector 110 when cleaning to the junction of the first current collector 110 and the first tab 130, until the exposed part of the first current collector 110 is cleaned. When the scraper is cleaned on the second surface 100b, it will not continue to move in the direction of the first current collector 110 when cleaning to the junction of the first current collector 110 and the first tab 130, and the first current collector 110 will not be exposed. In this way, the scraper can be cleaned in place to fully expose the aluminum foil to form a second empty foil area, and the first current collector 110 can be prevented from being damaged due to excessive cleaning of the scraper.

[0041] In the finally formed battery, the first side edge 1211 and the second side edge 1221 extend in the second direction, and the first side edge 1211 and the second side edge 1221 are arranged in a staggered manner in the first direction. The projection of the first side edge 1211 in the thickness direction of the first tab unit 100 is located on the first current collector 110, and the projection of the second side edge 1221 in the thickness direction of the first tab unit 100 is located on the first tab 130. One of the first surface 100a and the second surface 100b exposes part of the first current collector 110, and the other does not expose the first current collector 110.

[0042] The battery provided by the embodiments of the present disclosure comprises a first pole piece unit 100, the first pole piece unit 100 comprises a first current collector 110, a first active material layer 120, a first tab 130 and a first notch 140, the first active material layer 120 comprises a first active coating layer 121 and a second active coating layer 122, the first active coating layer 121 comprises a first side edge 1211, and the second active coating layer 122 comprises a second side edge 1221. The first active material layer 120 is arranged to react with electrolyte to generate current, the first current collector 110 is arranged to collect the current generated by the first active material layer 120, the first tab 130 is arranged to lead out the current of the first current collector 110, at least two first tabs 130 are connected to each other to form a first tab group, so as to improve the charge-discharge efficiency of the battery, the first notch 140 is arranged, so that after the first pole piece unit 100 is wound or stacked, at least two first notches 140 overlap to form a first accommodation groove 200 along the thickness direction of the first current collector 110, and then the first tab group is accommodated in the first accommodation groove 200, so as to avoid the first tab group increasing the invalid volume of the battery, thereby improving the energy density of the battery. The first side edge 1211 and the second side edge 1221 are arranged to be staggered along the first direction, so as to ensure the cleaning effect and prevent the first current collector 110 from being damaged during cleaning.

[0043] In some embodiments, along the first direction, the distance between the first side edge 1211 and the second side edge 1221 is greater than or equal to 0.5 mm and less than or equal to 2.5 mm.

[0044] If the distance between the first side edge 1211 and the second side edge 1221 is less than 0.5 mm, the distance between the first side edge 1211 and the second side edge 1221 is too small, which may result in that the second surface 100b is not cleaned well, and the cleaning effect is poor. If the distance between the first side edge 1211 and the second side edge 1221 is greater than 2.5 mm, the distance between the first side edge 1211 and the second side edge 1221 is too large, which may result in that the first surface 100a is cleaned too much, and then the first current collector 110 is damaged. Therefore, the distance between the first side edge 1211 and the second side edge 1221 is set to be between 0.5 mm and 2.5 mm, so as to improve the cleaning effect.

[0045] For example, the distance between the first side edge 1211 and the second side edge 1221 can be any one of 0.5 mm, 0.8 mm, 1 mm, 1.3 mm, 1.5 mm, 1.8 mm, 2 mm, 2.3 mm, 2.5 mm or within any two ranges. Since one of the first surface 100a and the second surface 100b exposes part of the first current collector 110, the other does not expose the first current collector 110, therefore, the projection of the first side edge 1211 and the second side edge 1221 along the thickness direction of the first tab unit 100, one of which is located on the first current collector 110, and the other is located on the first lug 130. In the present disclosure, the distance between the first side edge 1211 and the second side edge 1221 refers to the distance between the projection position of the first side edge 1211 on the first current collector 110 or the first lug 130 along the thickness direction of the first tab unit 100 and the projection position of the second side edge 1221 on the first lug 130 or the first current collector 110 along the thickness direction of the first tab unit 100.

[0046] Referring to FIGS. 2 to 4, in a specific embodiment, the first tab unit 100 further comprises an insulating layer 150, the insulating layer 150 comprises a first insulating coating layer 151, the first insulating coating layer 151 is arranged on the first surface 100a and is adjacent to the first side edge 1211, and the projection of the second side edge 1221 on the first insulating coating layer 151 is located within the first insulating coating layer 151.

[0047] It should be noted that after cleaning and before die cutting, an insulating material can be coated on the side of the second empty foil area away from the first empty foil area, so that the first insulating coating layer 151 is formed on the first surface 100a, the first insulating coating layer 151 is adjacent to the first side edge 1211, and the first insulating coating layer 151 can improve the safety of the battery.

[0048] Referring to FIGS. 2 to 5, it is worth mentioning that the second surface 100b can not be provided with an insulating layer 150, or can be provided with an insulating layer 150, and in a specific embodiment, the insulating layer 150 further comprises a second insulating coating layer 152, the second insulating coating layer 152 is arranged on the second surface 100b and is adjacent to the second side edge 1221.

[0049] That is, the opposite two surfaces of the first tab unit 100 are both provided with an insulating layer 150, and the second surface 100b can be provided with a second insulating coating layer 152, the second insulating coating layer 152 is adjacent to the second side edge 1221, so that the second insulating coating layer 152 can improve the safety of the battery.

[0050] When the first tab unit 100 is provided with only the first insulating coating 151, if the extension length of the first insulating coating 151 in the first direction is less than 0.1 mm, the effect of the first insulating coating 151 on improving the safety of the battery is limited, and if the extension length of the first insulating coating 151 in the first direction is greater than 2.4 mm, the first insulating coating 151 occupies a large area, which is not conducive to the welding between the plurality of first tabs 130 and is not conducive to increasing the area of the first active coating 121. Therefore, in a specific embodiment, the extension length of the first insulating coating 151 in the first direction is greater than or equal to 0.1 mm and less than or equal to 2.4 mm.

[0051] When the first tab unit 100 is provided with both the first insulating coating 151 and the second insulating coating 152, the ratio of the extension length of the first insulating coating 151 to the extension length of the second insulating coating 152 in the first direction is greater than or equal to 1.01 and less than or equal to 4. In this way, it can be ensured that the die-cutting position is on the insulating layer 150 during die-cutting, thereby preventing burrs from being generated during die-cutting and avoiding the extension of the first active material layer 120 to the first tab 130, thereby reducing the probability of lithium precipitation of the battery.

[0052] For example, the extension length of the first insulating coating 151 in the first direction can be any one of 0.1 mm, 0.3 mm, 0.6 mm, 1 mm, 1.3 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.4 mm or within any two value ranges. And / or, the ratio of the extension length of the first insulating coating 151 to the extension length of the second insulating coating 152 in the first direction can be any one of 1.01, 1.5, 1.8, 2, 2.3, 2.5, 2.8, 3, 3.3, 3.5, 3.8, 4 or within any two value ranges.

[0053] In a specific embodiment, the first insulating coating 151 includes a first region 1511 and a second region 1512 which are adjacent to each other, the projection of the first region 1511 on the thickness of the first tab unit 100 covers the first current collector 110, and the projection of the second region 1512 on the thickness of the first tab unit 100 covers the first tab 130. In this case, the side of the first region 1511 along the first direction has a spacing with the side of the first notch 140 along the first direction. That is, when the insulating material is coated, the insulating material is coated on the side of the second blank foil area away from the first blank foil area, and after the die cutting to form the first current collector 110 and the first tab 130 respectively, the first insulating coating 151 is located at the junction of the first current collector 110 and the first tab 130, that is, the first insulating coating 151 can include the first region 1511 located at the first current collector 110 and the second region 1512 located at the first tab 130, and the coating range of the insulating material along the second direction is not too large, and the two sides of the first region 1511 along the first direction do not overlap with the side of the first notch 140 along the first direction, thereby avoiding the first insulating layer 150 covering a large area of the first current collector 110, which reduces the area of the first active coating 121, thereby improving the energy density of the first tab unit 100.

[0054] Referring to FIG. 5, in a specific embodiment, the second active coating 122 includes a first coating region 1222 and a second coating region 1223 which are adjacent to each other, the first coating region 1222 is located at the first tab 130, and the second coating region 1223 is located at the first current collector 110. Along the first direction, the extension length of the first coating region 1222 is greater than or equal to 0.1 mm and less than or equal to 1 mm.

[0055] That is, when only the first surface 100a is provided with the first insulating coating 151, the second active coating 122 not only covers the first current collector 110, but also covers the first tab 130, thereby making the second active coating 122 include the first coating region 1222 located at the first tab 130 and the second coating region 1223 located at the first current collector 110, wherein the extension length of the first coating region 1222 along the first direction ranges from 0.1 mm to 1 mm, so as to avoid excessive cleaning which damages the first current collector 110, and to avoid the area of the first coating region 1222 being too large which affects the welding between the plurality of first tabs 130.

[0056] In some embodiments, the ratio of the thickness of the insulation layer 150 to the thickness of the first active material layer 120 is greater than or equal to 0.1 and less than or equal to 0.9. That is, the insulation layer 150 is thinner than the first active material layer 120. In this way, the insulation layer 150 can have a certain thickness to improve the safety of the battery, while avoiding the first active material layer 120 and the insulation layer 150 mixing when the battery generates heat, thereby reducing the capacity of the battery.

[0057] And / or, along the first direction, the ratio of the extension length of the first notch 140 to the extension length of the insulation layer 150 is greater than or equal to 1.2 and less than or equal to 3.5. In this way, the edge of the first notch 140 can be prevented from exposing the first current collector 110, thereby preventing the battery from short-circuiting and other safety problems.

[0058] And / or, along the first direction, the ratio of the extension length of the insulation layer 150 to the extension length of the first tab 130 is greater than or equal to 1.1 and less than or equal to 3. In this way, the die cutting position can be ensured to be on the insulation layer 150 during die cutting, thereby preventing burrs from being generated during die cutting, and thereby reducing the probability of lithium precipitation in the battery.

[0059] And / or, along the second direction, the ratio of the extension length of the first notch 140 to the extension length of the first tab 130 is greater than or equal to 2.5 and less than or equal to 5. It should be understood that when the first tab unit 100 is wound, the first notches 140 of different folded layers are difficult to completely coincide, and therefore a certain tolerance is required. The extension length of the first notch 140 along the second direction can be appropriately set to be greater than the width of the first tab 130, thereby enabling the first tab group to be completely accommodated in the first accommodation groove 200, and when the first tabs 130 of different folded layers have different widths, each first tab 130 of the first tab group can be completely accommodated in the first accommodation groove 200.

[0060] For example, the ratio of the thickness of the insulation layer 150 to the thickness of the first active material layer 120 can be any one of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or within any two ranges. And / or, the ratio of the extension length of the first notch 140 to the extension length of the insulation layer 150 in the first direction can be any one of 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5 or within any two ranges. And / or, the ratio of the extension length of the insulation layer 150 to the extension length of the first tab 130 in the first direction can be any one of 1.1, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3 or within any two ranges. And / or, the ratio of the extension length of the first notch 140 to the extension length of the first tab 130 in the second direction can be any one of 2.5, 3, 3.5, 4, 4.5, 5 or within any two ranges.

[0061] Referring to FIG. 2, in a specific embodiment, the first tab unit 100 further has a second notch 160, the first notch 140 and the second notch 160 are arranged in the second direction with a spacing, and the first notch 140 and the second notch 160 are located on the same side of the first current collector 110, and at least two second notches 160 overlap in the thickness direction of the first current collector 110 to form a second accommodation groove.

[0062] In the second direction, the ratio of the extension length of the first notch 140 to the extension length of the second notch 160 is greater than or equal to 0.4, greater than or equal to 0.9.

[0063] Referring to FIGS. 2, 7 and 8, in a specific embodiment, the battery further comprises a second tab unit 300, the polarity of the second tab unit 300 is opposite to that of the first tab unit 100, and the first tab unit 100 and the second tab unit 300 are arranged in a stack.

[0064] The second tab unit 300 comprises a second current collector 310, a second active material layer 320 and a third notch 330, at least two third notches 330 overlap in the thickness direction of the first current collector 110, and the third notch 330 is arranged corresponding to the first notch 140 to jointly define the first accommodation groove 200. The second active material layer 320 is arranged on opposite two sides of the second tab unit 300, and in the first direction, the side of the second active material layer 320 close to the first tab 130 has a third side edge 321, and the projection of the first tab unit 100 on the third side edge 321 is located in the insulation layer 150.

[0065] It should be understood that the process flow of the second tab unit 300 is similar to that of the first tab unit 100, and can also include coating, cleaning, and die cutting, and the like. In cleaning, unlike the offset cleaning of the opposite two sides of the first tab unit 100, there is no obvious difference in cleaning the opposite two sides of the second tab unit 300. After cleaning, the second active material layer 320 on the opposite two sides of the second tab unit 300 forms a third side edge 321. Within the allowable range of tolerance, the third side edges 321 on the opposite two sides of the second tab unit 300 can coincide, and the projection of the third side edge 321 on the insulating layer 150 is located within the insulating layer 150. This makes the content of the second active material of the second active material layer 320 higher than the content of the first active material of the first active material layer 120, and further makes the lithium ion have sufficient attachment sites on the second tab unit 300, thereby reducing the probability of lithium precipitation of the battery, thereby improving the safety performance of the battery.

[0066] The projection of the third side edge 321 on the first insulating coating 151 is located within the first insulating coating 151, and / or the projection of the third side edge 321 on the second insulating coating 152 is located within the second insulating coating 152.

[0067] Referring to FIGS. 2, 7, and 8, in some embodiments, the second tab unit 300 further includes second tabs 340 and fourth notches 350. The second tabs 340 are connected to the second current collector 310. At least two second tabs 340 are connected to each other to form a second tab group. At least two fourth notches 350 overlap along the thickness direction of the second current collector 310. The fourth notches 350 and the second notches 160 are correspondingly arranged to jointly define a second accommodation groove. The second tab group is at least partially located in the second accommodation groove.

[0068] It should be noted that compared with a single second tab 340, the second tab group formed by the plurality of second tabs 340 connected to each other can improve the charge and discharge efficiency of the battery. For example, the first tab group is used to lead out the positive electrode current, and the second tab group is used to lead out the negative electrode current.

[0069] The second accommodation groove is used to accommodate the plurality of second tabs 340 connected to form the second tab group, so that the second tab group does not increase the invalid volume of the battery, thereby improving the energy density of the battery.

[0070] Since the width of the first tab 130 is smaller than the width of the second tab 340, the first accommodation groove 200 defined by the plurality of first notches 140 is used to accommodate the first tab group, and the second accommodation groove defined by the plurality of second notches 160 is used to accommodate the second tab group. Therefore, the extension length of the first notch 140 along the second direction is smaller than the extension length of the second notch 160 along the second direction.

[0071] For example, in the second direction, the ratio of the extension length of the first notch 140 to the extension length of the second notch 160 can be any one of 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or within any two ranges thereof, so as to ensure that the first receiving groove 200 is sufficient to accommodate the first tab group and that the second receiving groove is sufficient to accommodate the second tab group.

[0072] In some embodiments, the diaphragm disposed between the first tab unit 100 and the second tab unit 300 can also be provided with a fifth notch and a sixth notch, the first notch 140, the third notch 330 and the fifth notch being correspondingly disposed to jointly define the first receiving groove 200. The second notch 160, the fourth notch 350 and the sixth notch are correspondingly disposed to jointly define the second receiving groove.

[0073] In some embodiments, the first notch 140 has a first rounded corner between adjacent sides thereof, the diameter of the first rounded corner being greater than or equal to 1 mm. And / or, the fourth notch 350 has a second rounded corner between adjacent sides thereof, the diameter of the second rounded corner being greater than or equal to 1 mm.

[0074] In this way, when the first notch 140 and the second notch 160 are formed by die cutting, the stress generated during die cutting can be reduced, thereby avoiding stress concentration between the adjacent sides of the first notch 140 and between the adjacent sides of the fourth notch 350, so as to avoid subsequent cracking of the first notch 140 and the second notch 160.

[0075] For example, the diameter of the first rounded corner can be any one of 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm or within any two ranges thereof. And / or, the diameter of the second rounded corner can be any one of 1 mm, 1.1 mm, 1.4 mm, 1.6 mm, 1.8 mm or within any two ranges thereof.

[0076] In some embodiments, the battery is a lithium ion secondary battery.

[0077] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present disclosure, and not to limit them; although the present disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A battery, characterized by, The first and second polar sheet units are stacked to form an electrode core, the first polar sheet unit comprises a first current collector, a first active material layer, a plurality of first tabs and a plurality of first notches, the second polar sheet unit comprises a plurality of second tabs, the first tabs are connected to the first current collector, a plurality of the first notches overlap to form a first receiving groove along the thickness direction of the first current collector, and a plurality of the first tabs are stacked to form a first tab group, the first tab group is at least partially located in the first receiving groove; The first polar sheet unit has opposite first and second surfaces, the first active material layer comprises a first active coating and a second active coating, the first active coating is arranged on the first surface, and the second active coating is arranged on the second surface; The first active coating has a first side edge on one side close to the first tab, the second active coating has a second side edge on one side close to the first tab, and the first side edge and the second side edge both extend along a second direction, and the first side edge and the second side edge are arranged staggered along a first direction.

2. The battery of claim 1, wherein, Along the first direction, the distance between the first side edge and the second side edge is greater than or equal to 0.5 mm and less than or equal to 2.5 mm.

3. The battery according to claim 1 or 2, characterized in that, The first polar sheet unit further comprises an insulating layer, the insulating layer comprises a first insulating coating, the first insulating coating is arranged on the first surface and adjacent to the first side edge, and the projection of the second side edge in the thickness direction of the first polar sheet unit is located in the first insulating coating; Preferably, the extension length of the first insulating coating is greater than or equal to 0.1 mm and less than or equal to 2.4 mm.

4. The battery of claim 3, wherein, The insulating layer further comprises a second insulating coating, the second insulating coating is arranged on the second surface and adjacent to the second side edge.

5. The battery of claim 4, wherein, Along the first direction, the ratio of the extension length of the first insulating coating to the extension length of the second insulating coating is greater than or equal to 1.01 and less than or equal to 4.

6. The battery of any one of claims 3-5, wherein, The first insulating coating comprises a first region and a second region adjacent to each other, the projection of the first region on the thickness of the first polar sheet unit covers the first current collector, and the projection of the second region on the thickness of the first polar sheet unit covers the first tab; The side edge of the first region along the first direction has a spacing with the side edge of the first notch along the first direction.

7. The battery of any one of claims 1-6, wherein, The second active coating comprises a first coating region and a second coating region adjacent to each other, the first coating region is located on the first tab, and the second coating region is located on the first current collector; Along the first direction, the extension length of the first coating region is greater than or equal to 0.1 mm and less than or equal to 1 mm.

8. The battery of claim 3, wherein, The ratio of the thickness of the insulating layer to the thickness of the first active material layer is greater than or equal to 0.1 and less than or equal to 0.9; And / or, along the first direction, the ratio of the extension length of the first notch to the extension length of the insulating layer is greater than or equal to 1.2 and less than or equal to 3.5; And / or, along the second direction, the ratio of the extension length of the insulating layer to the extension length of the first tab is greater than or equal to 1.1 and less than or equal to 3; And / or, along the first direction, the ratio of the extension length of the first notch to the extension length of the first tab is greater than or equal to 2.5 and less than or equal to 5.

9. The battery of any one of claims 1-8, wherein, The first tab unit further has a plurality of second notches, the first notches and the second notches are arranged at intervals along the second direction, and the first notches and the second notches are located on the same side of the first current collector, a plurality of the second notches overlap to form a second accommodation groove along the thickness direction of the first current collector, and a plurality of the second tabs are stacked to form a second tab group, the second tab group is at least partially located in the second accommodation groove.

10. The battery of claim 9, wherein, Along the second direction, the ratio of the extension length of the first notch to the extension length of the second notch is greater than or equal to 0.4 and greater than or equal to 0.

9.

11. The battery of any one of claims 3-10, wherein, The second tab unit further includes a second current collector, a second active material layer, and a plurality of third notches, the third notches overlap in the thickness direction of the first current collector, and the third notches are arranged correspondingly to the first notches. The second active material layer is arranged on opposite surfaces of the second tab unit, and along the first direction, one side of the second active material layer close to the first tab has a third side edge, and the projection of the third side edge in the thickness direction of the first tab unit is located in the insulating layer.

12. The battery of any one of claims 9-11, wherein, The second tab unit further includes a plurality of fourth notches, the second tabs are connected to the second current collector, a plurality of the fourth notches overlap in the thickness direction of the second current collector, and the fourth notches are arranged correspondingly to the second notches.

13. The battery of any one of claims 1-12, wherein, The first notches have a first round corner between adjacent side edges, and the diameter of the first round corner is greater than or equal to 1 mm.

14. The battery of claim 12 or 13, wherein, The fourth notches have a second round corner between adjacent side edges, and the diameter of the second round corner is greater than or equal to 1 mm.

15. The battery of any one of claims 1-14, wherein, The battery is a lithium ion secondary battery.

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