WO2023103994A1

WO2023103994A1 - Electrode plate and battery

Info

Publication number: WO2023103994A1
Application number: PCT/CN2022/136699
Authority: WO
Inventors: 彭宁
Original assignee: 珠海冠宇电池股份有限公司
Priority date: 2021-12-06
Filing date: 2022-12-05
Publication date: 2023-06-15
Also published as: CN216354302U

Abstract

The present application provides an electrode plate and a battery. The electrode plate comprises an electrode plate body and a tab, wherein the electrode plate body comprises a current collector and two active substance layers, and the two active substance layers are respectively arranged on two opposite side faces of the current collector; at least one active material layer is provided with a groove, the current collector is arranged on a bottom wall of the groove, and the tab is arranged in the groove and is welded to the current collector to form a welding spot; and the welding spot is in the shape of a circle, and the diameter of the welding spot ranges from 0.03 mm to 2 mm. The electrode plate provided in the present application has a relatively high reliability after welding, and the energy density of a battery is relatively high.

Description

Electrode and battery

This application claims the priority of the Chinese patent application with the application number 202123048902.7 and the application name "pole piece and battery" submitted to the China Patent Office on December 06, 2021, the entire content of which is incorporated in this application by reference.

technical field

The present application relates to the technical field of lithium batteries, in particular to a pole piece and a battery.

Background technique

Lithium-ion batteries have the advantages of large capacity, low energy density, small volume, light weight and environmental protection, and have been widely used in digital electronic products and electric vehicles and other industries.

A lithium-ion battery includes a positive electrode, a negative electrode, and a separator. Usually, a positive electrode ear is welded on the positive electrode sheet, and a negative electrode ear is welded on the negative electrode sheet. The positive electrode ear and the negative electrode ear are used for electrical connection with an external circuit to charge or discharge the lithium-ion battery. After the positive/negative tabs are welded, a large number of burrs are formed at the welding position. After welding, the positive electrode sheet, negative electrode sheet and separator are wound to form a battery cell. After the battery cell is installed inside the battery case, a lithium-ion battery can be formed.

However, in the prior art, after the tabs are welded, the strength of the welded area between the tabs and the current collector is weak, resulting in low reliability of the pole piece, and thus lower energy density of the battery.

Contents of the invention

The present application provides a pole piece and a battery to solve the problem that in the prior art, after the tabs are welded, the strength of the welded area between the tabs and the current collector is weak, resulting in low reliability of the pole piece, which in turn reduces the energy of the battery. less dense issues.

The present application provides a pole piece, including a pole piece body and tabs. The pole piece body includes a current collector and two active material layers, and the two active material layers are respectively arranged on two opposite sides of the current collector;

At least one active material layer has a groove, the bottom wall of the groove is a current collector, and the tab is arranged in the groove and welded with the current collector to form a solder joint;

The solder joint is in a circular shape, and the diameter of the solder joint is 0.03 mm to 2 mm.

In a possible implementation manner, in the pole piece provided by the present application, the two active material layers include a first active material layer and a second active material layer, and the first active material layer and the second active material layer are respectively located on the sides of the current collector. opposite sides;

The first active material layer has a groove, the surface of the current collector facing away from the groove is provided with the second active material layer, and the projection of the groove on the current collector is located within the projection of the second active material layer on the current collector.

In a possible implementation manner, in the pole piece provided by the present application, there are multiple welding spots, and the welding spots are arranged at intervals, and the distance between adjacent welding spots is 0.001mm-5mm.

In a possible implementation manner, in the pole piece provided by the present application, each welding spot is arranged in a rectangular array or in a circular array.

In a possible implementation manner, in the pole piece provided by the present application, at least part of the welding spots are located on the surface of the tab on the side away from the current collector, and protrude toward the side away from the current collector to form a raised portion.

In a possible implementation manner, in the pole piece provided by the present application, the height of the protrusion is equal to or less than 50% of the diameter of the welding spot.

In a possible implementation manner, in the pole piece provided by the present application, there is a welding area in the groove, and the welding point is located in the welding area;

The width of the welding area is 50%-100% of the width of the tab, and/or the length of the welding area is 50%-100% of the length of the overlapping part of the tab and the current collector.

In a possible implementation manner, for the pole piece provided in the present application, the thickness of the tab is 0.01 mm to 0.5 mm, and/or the width of the tab is 1 mm to 12 mm, and/or the length of the tab is 5 mm ~50mm.

In a possible implementation manner, in the pole piece provided by the present application, the thickness of the tab is greater than or equal to the depth of the groove.

The present application provides a battery, including the above pole piece.

The application provides a pole piece and a battery. The pole piece includes a pole piece body and tabs. The pole piece body includes a current collector and two active material layers, and the two active material layers are respectively arranged on opposite sides of the current collector; at least There is a groove on one active material layer, the bottom wall of the groove is a current collector, and the tab is arranged in the groove and welded with the current collector to form a solder joint; the solder joint is in a circular shape, and the diameter of the solder joint is 0.03mm ~2mm. By setting the structure, quantity and arrangement of solder joints between tabs and current collectors. It can effectively increase the welding strength between the tab and the current collector, and improve the reliability of the pole piece after welding. At the same time, the advantage of the dot shape solder joint is that when it is subjected to pulling force in different directions, the stress state is the same, and there is no weak area, so that the drop test of the battery made of the welded pole piece is stable at all angles. can meet the requirements. It solves the problem in the prior art that after the tabs are welded, the strength of the welded area between the tabs and the current collector is weak, resulting in low reliability of the pole piece and thus a low energy density of the battery.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present application. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is the structural representation of the pole piece provided by the present application;

Fig. 2 is the sectional view of A-A place in Fig. 1;

Fig. 3 is the schematic diagram of the welding area provided by the present application;

Fig. 4 is the enlarged schematic view of position B in Fig. 3;

Fig. 5 is the sectional view of C-C place among Fig. 4;

Figure 6 is a schematic diagram of the second welding area provided by the present application;

Figure 7 is a schematic diagram of the third welding area provided by the present application;

Figure 8 is a schematic diagram of the fourth welding area provided by the present application;

Fig. 9 is a schematic diagram of the fifth welding area provided by the present application;

FIG. 10 is a schematic structural view of the cell provided by the present application.

Explanation of reference signs

10-pole piece;

11 - Positive plate;

12 - Negative electrode sheet;

20 - diaphragm;

100-pole piece body;

110-collector;

111 - welding area;

112-welding spot;

113 - raised portion;

120 - active material layer;

120a - the first active material layer;

120b - the second active material layer;

121 - groove;

200-pole ear;

210 - pole ear glue;

310-insulating adhesive layer;

D0 - the diameter of the solder joint;

L0- the distance between solder joints;

D- the width of the tab;

L-the length of the overlapping part of the tab and the current collector;

D1 - the width of the welding area;

L1 - the length of the welding area;

L10- pole piece body length;

L11 - the distance between the groove and one end of the pole piece body.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments It is a part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of this application.

In the description of this application, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be fixedly connected, or through an intermediate The media is indirectly connected, which can be the internal communication of two elements or the interaction relationship between two elements. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application according to specific situations.

In the description of this application, it is to be understood that the terms "upper", "lower", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", The orientation or positional relationship indicated by "outside" is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the application and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, constructed and operated in a particular orientation and therefore should not be construed as limiting the application.

The terms "first", "second", and "third" (if any) in the description and claims of the present application and the above drawings are used to distinguish similar objects and not necessarily to describe a specific order or priority. It is to be understood that the data so used are interchangeable under appropriate circumstances such that the embodiments of the application described herein, for example, can be practiced in sequences other than those illustrated or described herein.

Furthermore, the terms "comprising" and "having", as well as any variations thereof, are intended to cover a non-exclusive inclusion, for example, a process, method, system, product or maintenance tool comprising a series of steps or units need not be limited to the expressly listed Instead, other steps or elements not explicitly listed or inherent to the process, method, product or maintenance tool may be included.

Lithium-ion battery is a secondary battery (rechargeable battery), which mainly relies on lithium ions to move back and forth between the positive and negative electrodes to work. During the charge/discharge process, lithium ions intercalate and deintercalate back and forth between the positive and negative electrodes. When charging, lithium ions are deintercalated from the positive electrode, inserted into the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; the opposite is true when discharging. As a new type of energy storage battery, due to its advantages of high energy, long life, low energy consumption, pollution-free, no memory effect, small self-discharge, low internal resistance, high cost performance, and less pollution, lithium-ion batteries are gradually being used in applications. It shows great advantages, and it is widely used in various fields such as mobile phones, notebook computers, video cameras, digital cameras, electric vehicles, energy storage, and aerospace.

A lithium-ion battery mainly includes a casing, a pole piece and a separator. The pole piece includes a positive pole piece and a negative pole piece. The separator is arranged between the positive pole piece and the negative pole piece, and is wound together with the positive pole piece and the negative pole piece to form a battery core. A lithium-ion battery is formed after a casing is installed outside the battery cell. Wherein, a tab is connected to the pole piece, and the tab is used for connecting with an external circuit to charge or discharge the battery. The tabs include positive tabs arranged on the positive sheet and negative tabs arranged on the negative sheet. Since the tabs are made of metal materials that are easy to conduct electricity, in order to improve the conduction capacity of the current between the tabs and the pole pieces, welding is usually used to weld them on the pole pieces so that the gap between the tabs and the pole pieces electrical connection. After the positive/negative tabs are welded, a large number of burrs are formed at the welding position. After welding, the positive electrode sheet, negative electrode sheet and separator are wound to form a battery cell. After the battery cell is installed inside the battery case, a lithium-ion battery can be formed. However, in the prior art, after the tabs are welded, the strength of the welded area between the tabs and the current collector is weak, resulting in low reliability of the pole piece, and thus lower energy density of the battery.

Based on this, the present application provides a pole piece and a battery. By setting the structure, quantity and arrangement of solder joints between the tab and the current collector, the welding strength between the tab and the current collector can be effectively increased, and the pole piece can be improved. Reliability after soldering. At the same time, the advantage of the dot shape solder joint is that when it is subjected to pulling force in different directions, the stress state is the same, and there is no weak area, so that the drop test of the battery made of the welded pole piece is stable at all angles. can meet the requirements.

Example

Fig. 1 is a schematic structural view of the pole piece provided by the present application, Fig. 2 is a cross-sectional view at the A-A place in Fig. 1, Fig. 3 is a schematic diagram of the welding area provided by the present application, Fig. 4 is an enlarged schematic diagram at the B position in Fig. 3, Fig. 5 is a cross-sectional view at C-C in FIG. 4 . As shown in Figures 1 and 2, the present application provides a pole piece 10, including a pole piece body 100 and a tab 200, the pole piece body 100 includes a current collector 110 and two active material layers 120, and the two active material layers 120 They are respectively arranged on two opposite side surfaces of the current collector 110 .

As shown in Figure 3 and Figure 4, at least one active material layer 120 has a groove 121, the bottom wall of the groove 121 is the current collector 110, the tab 200 is arranged in the groove 121, and welded with the current collector 110 to form Welding spot 112; the welding spot 112 is in a circular shape, and the diameter of the welding spot 112 is 0.03mm-2mm.

In this embodiment, the pole piece 10 is a component arranged inside the battery for charging and discharging. The pole piece 10 includes a pole piece body 100 and a pole lug 200. The pole piece body 100 is composed of a current collector 110 and two active material layers 120. The two active material layers 120 are arranged on opposite sides of the current collector 110 to form A pole piece body 100 stacked in layers.

The current collector 110 on the pole piece 10 is made of metal material, usually aluminum (Al), nickel (Ni), copper (Cu) or nickel-plated copper (Ni—Cu) alloy. The active material layer 120 is composed of materials such as active material, conductive agent and adhesive. After coating two active material layers 120 on two opposite sides of the current collector 110 respectively, the pole piece body 100 is formed.

In order to facilitate the welding of the tab 200 , a groove 121 is provided on the active material layer 120 on one side of the pole piece body 100 . Specifically, the active material coated in a specific area on the surface of the active material layer 120 is scraped off by laser cleaning, foaming or mechanical techniques, so that the surface of the current collector 110 covered by the active material in this area leaks out, For welding the tab 200 .

Please continue to refer to FIG. 1 , the groove 121 is located in the middle region of the pole piece body 100 , and the distance from the groove 121 to one end of the pole piece body 100 is 1/3˜2/3 of the total length of the pole piece body 100 . Specifically, the length of the pole piece body 100 is L10, the distance between the groove 121 and one end of the pole piece body 100 is L11, and L11 is 1/3˜2/3 of L10. The groove 121 has a width ranging from 2 mm to 30 mm, a length ranging from 2 mm to 40 mm, and a depth ranging from 0.01 mm to 1 mm.

The tabs 200 are metal conductors that lead out the electrodes from the battery, that is, the contact points when the battery is charging/discharging. This contact point is not the copper piece that is usually seen on the outside of the battery, but a component inside the battery that is used to electrically connect the pole piece to the protection circuit. The tab 200 is mainly formed of three materials, usually aluminum (Al), nickel (Ni), copper (Cu) or copper nickel-plated (Ni-Cu) alloy, etc., which are made of two parts: film and metal strip. Composite.

Please continue to refer to FIGS. 1-4 , the tab 200 is disposed in the groove 121 , and the tab 200 may be welded to the current collector 110 on the bottom wall of the groove 121 . There are multiple welding spots 112, and the shape of the welding spots 112 is circular. The diameter D0 of each solder joint 112 ranges from 0.03 mm to 2 mm. The solder joint 112 is a solder pool formed after the tab 200 and the current collector 110 are heated, and the solder joint 112 runs through the tab 200 and is partially housed inside the current collector 110 . The depth of the part of the welding spot 112 inside the current collector 110 is 50%-100% of the thickness of the current collector 110 . In this way, the tab 200 can be electrically connected to the current collector 110 , and current can flow back and forth between the tab body 100 and the external circuit through the tab 200 .

Please continue to refer to FIG. 2 and FIG. 3, the two active material layers 120 include a first active material layer 120a and a second active material layer 120b, and the first active material layer 120a and the second active material layer 120b are respectively located in the current collector 110 the opposite sides of the

The first active material layer 120a has a groove 121, the surface of the current collector 110 facing away from the groove 121 is provided with a second active material layer 120b, and the projection of the groove 121 on the current collector 110 is located on the surface of the second active material layer 120b 110 inside the projection.

In a specific implementation, the active material layer 120 may include a first active material layer 120a and a second active material layer 120b respectively disposed on opposite sides of the current collector 110, and a groove 121 may be provided on the first active material layer 120a. The bottom wall of 121 is the current collector 110 , and the tab 200 can be welded on the surface of the current collector 110 in the groove 121 . The projection of the groove 121 on the current collector 110 is located within the projection of the second active material layer 120b on the current collector 110, so that it can be ensured that the second active material layer 120b completely covers the surface of the current collector 110 facing away from the groove 121 .

In some embodiments, the tab 200 is welded on the current collector 110 by laser welding. Specifically, firstly, the first active material layer 120a and the second active material layer 120b are respectively coated on the opposite side surfaces of the current collector 110, and the first active material layer 120a on one side surface of the current collector 110 is disposed In the groove 121 , the exposed surface of the current collector 110 in the groove 121 forms a welding region 111 , and the surface of the current collector 110 facing away from the groove 121 has a second active material layer 120b. The current collector 110 and the second active material layer 120b together serve as a bottom layer. The tab 200 is placed in the groove 121 above the current collector 110, and the tab 200 is fixed in the groove 121 by fixtures (not shown in the figure) and other tools, and the pressure between the tab 200 and the current collector 110 is maintained. tight state.

Set the pulse width of the laser (not shown in the figure) to be less than or equal to 1 ms, set the welding time to be less than or equal to 5 seconds, set the welding trajectory to be circular, and the diameter D0 of the circular solder spot 112 is 0.03 mm to 2 mm, and the maximum diameter The reason why the numerical value is limited to 2 mm is that when the diameter of the circular solder joint 112 exceeds 2 mm, the heat accumulation of laser welding is relatively large, which is likely to have an adverse effect on the active material on the back side, causing welding back marks on the active material on the back side of the solder joint 112 . The laser beam strikes the surface of the tab 200 away from the current collector 110 through the fixture, and forms a plurality of circular welding spots 112 on the surface. The distance L0 between the circular solder joints 112 is 0.001 mm˜5 mm. The second active material layer 120b on the other side surface of the solder joint 112 away from the tab 200 is not affected in any way.

After the laser welding is completed, the tab 200 is completely penetrated, that is, the depth of the molten pool at the tab 200 is the thickness of the tab 200, the thickness direction of the current collector 110 is partially or completely melted to form a molten pool, and the depth of the molten pool at the current collector 110 is 10%-100% of the thickness of the fluid 110 . Such setting can ensure the reliable connection between the tab 200 and the current collector 110 , and reduce the influence of welding on the second active material layer 120 b covered on the surface of the current collector 110 facing away from the tab 200 . The advantage of such setting is that the welding strength between the tab 200 and the current collector 110 can be effectively increased, and the reliability of the pole piece 10 after welding can be improved. At the same time, the advantage of the dot shape solder joint 112 is that when it is subjected to pulling force in different directions, the stress state is consistent, and there is no weak area, so that the electric core made of the pole piece 10 after welding will drop at various angles. All tests meet the requirements.

Please continue to refer to FIG. 3-FIG. 5 , there are multiple solder joints 112 , and each solder joint 112 is arranged at intervals, and the distance between adjacent solder joints 112 is 0.001 mm˜5 mm. The welding spots 112 are arranged in a rectangular array or in a circular array. At least part of the welding spot 112 is located on the surface of the lug 200 away from the current collector 110, and protrudes toward the side away from the current collector 110 to form a raised portion 113. The height of the raised portion 113 is equal to or smaller than the diameter of the welding spot 112 50% of.

Please continue to refer to FIG. 3 and FIG. 4, in some embodiments, a welding area 111 is provided on the surface of the current collector 110 in the groove 121 on the pole piece body 100, and the welding area 111 communicates with the groove 121, and the tab 200 is welded on the welding area 111 through the welding spot 112 . There are multiple welding spots 112 in the welding area 111 , and the welding spots 112 are arranged at intervals in the welding area 111 . The specific arrangement can be arranged in the form of a rectangular array, a circular array, a rhombus array, a triangular array, or a character wait.

Figure 6 is a schematic diagram of the second welding area provided by the application, Figure 7 is a schematic diagram of the third welding area provided by the application, Figure 8 is a schematic diagram of the fourth welding area provided by the application, and Figure 9 is a schematic diagram of the application A schematic diagram of the fifth welding area is provided.

Specifically, a plurality of welding spots 112 may be arranged in a rectangular array as shown in FIG. 5 and FIG. 6 , and be distributed in the welding area 111 . A plurality of welding spots 112 may also be distributed in the welding area 111 in the form of a diamond array arrangement as shown in FIG. 7 . A plurality of welding spots 112 may also be distributed in the welding area 111 in the form of a circular array as shown in FIGS. 8 and 9 . It should be noted that this embodiment only takes the above several arrangement manners as examples for explanation.

The appearance of the solder joint 112 is irregular protrusions and depressions, and the raised part on the side of the solder joint 112 away from the current collector 110 forms a raised portion 113, and the raised portion 113 exceeds the surface of the tab 200, and its The maximum height beyond the surface of the tab 200 is less than or equal to 50% of the diameter of the solder joint 112 . The sum of the areas of the protrusions 113 is less than or equal to 50% of the area of the side of the solder joint 112 facing away from the current collector 110, that is to say, the proportion of the area of the protrusion 113 on the solder joint 112 is greater than or equal to 50%. This setting can increase the solder joint The total area of the raised part on 112 is to reduce the burrs on the surface of solder joint 112. Such a shape has a lower overall protrusion and a larger raised area, which is not easy to pierce the diaphragm, and improves the safety performance of the battery.

Please continue to refer to FIG. 1 and FIG. 3 , the width of the welding area is 50%-100% of the width of the tab, and/or the length of the welding area is 50%-100% of the length of the overlapping part of the tab and the current collector.

In some embodiments, after the tab 200 is welded on the current collector 110, a part of the tab 200 is located in the groove 121 and overlaps with the current collector 110, and another part of the tab 200 is located outside the groove 121. . In order to improve the reliability of the tab 200 and the current collector 110 on the pole piece body 100 after welding, in this embodiment, the area of the welding region 111 is increased to improve the reliability of the tab 200 after welding. Specifically, the width of the welding area 111 is set to 50%-100% of the width of the tab 200 , and the length of the welding area 111 is set to 50%-100% of the length of the overlapping part of the tab 200 with the current collector 110 . Wherein, the width of the tab 200 is D, and the length of the overlapping part of the tab 200 and the current collector 110 is L, the width D1 of the welding area 111 is 0.5 times to 1 time of D, and the length L1 of the welding area 111 is 0.5 times of L. Times ~ 1 times.

Please continue to refer to FIG. 1 and FIG. 2, the thickness of the tab 200 is 0.01 mm to 0.5 mm, and/or the width of the tab 200 is 1 mm to 12 mm, and/or the length of the tab 200 is 5 mm to 50 mm .

In some embodiments, in order to improve the electrical conductivity of the tab 200 , the size of the tab 200 is generally set relatively larger. Generally, the thickness of the tab 200 ranges from 0.01 mm to 0.5 mm, the width of the tab 200 ranges from 1 mm to 12 mm, and the length of the tab 200 ranges from 5 mm to 50 mm.

Please continue to refer to FIG. 2 , the thickness of the tab 200 is greater than or equal to the depth of the groove 121 .

In this embodiment, in order to ensure the electrical conductivity of the tab 200 and prevent the tab 200 from being welded through, the thickness of the tab 200 is greater than or equal to the depth of the groove 121 . Because within a reasonable size range, the thickness of the tab 200 is directly proportional to the conductivity, that is, the thicker the tab 200 is, the stronger its conductivity is. At the same time, the increased thickness of the tab 200 can effectively prevent the tab 200 from being welded through during welding, thereby improving the welding yield.

Please continue to refer to FIG. 1 and FIG. 3 , there is also a tab glue 210 on the tab 200, and the tab glue 210 is bonded to two opposite sides of the tab 200 for insulating and sealing the tab 200, Prevent the short circuit phenomenon of the tab 200 .

Please continue to refer to Fig. 1 and Fig. 2, in order to improve the insulation performance at the welding position after the tab 200 is welded, an insulating adhesive layer 310 is attached to the surface of the groove 121 in this application, and the thickness dimension of the insulating adhesive layer 310 The range is 0.001mm˜0.1mm, and its length/width are larger than the length/width of the groove 121 respectively. The purpose of this setting is that the insulating glue layer 310 can completely cover the welding area 111, part of the tab 200 and the entire groove 121, so that the tab 200 and the current collector 110 inside the groove 121 can be completely sealed and insulated to avoid Risk of battery short circuit.

The present application provides a pole piece 10 , including a current collector 110 , a first active material layer 120 a , a second active material layer 120 b , a tab 200 , and a groove 121 . The groove 121 is located on the first active material layer 120a on the pole piece 10, the tab 200 is placed inside the groove 121, the tab 200 is connected to the current collector 110 by laser welding, and the second active material layer 120b on the back of the tab 200 has no influence , so there is no need to paste an insulating layer on the back.

Wherein, the thickness of the current collector 110 is 0.001mm-0.02mm, and the material of the tab 200 is aluminum, copper, nickel and other metals. The surface of the tab 200 has a special coating for improving the laser absorption rate of the tab 200 . The tab 200 has a width of 1mm-20mm, a length of 5mm-100mm, and a thickness of 0.01mm-1mm.

The groove 121 is obtained by laser cleaning, foaming, mechanical and other techniques. The width of the groove 121 is 2mm-30mm, the length is 2mm-40mm, and the depth is 0.01mm-1mm. The tab 200 is placed in the middle of the groove 121 , and the distance from the groove 121 to one end of the pole piece 10 is 1/3˜2/3 of the total length of the pole piece 10 .

The groove 121 can have a notch (not shown in the figure), and the notch has the following characteristics: its width is 80%-120% of the corresponding groove 121 width, and its length is 1%-50% of the corresponding groove 121 length.

The insulating adhesive layer 310 covers the solder joint 112 , part of the lug 200 and the entire groove 121 . The thickness of the insulating adhesive layer 310 is 0.001-0.1 mm, and its length/width is greater than that of the groove 121 .

The battery cell is made from the pole piece 10 through processes such as winding, packaging, liquid injection, and chemical formation. This kind of battery cell can meet the drop test at various angles due to its high welding reliability.

FIG. 10 is a schematic structural view of the cell provided by the present application. As shown in FIG. 10 , the present application provides a cell structure, including a wound positive electrode sheet 11, a negative electrode sheet 12, and a separator 20. The separator 20 is located between the positive electrode sheet 11 and the negative electrode sheet 12. The positive electrode sheet 11 and/or The negative electrode sheet 12 is the above-mentioned electrode sheet 10 .

Specifically, the pole piece body 100 of the positive pole piece 11 includes a current collector 110 , a first active material layer 120 a and a second active material layer 120 b. The current collector 110 is made of aluminum (Al), and the thickness of the current collector 110 is 0.008mm. The composition materials of the first active material layer 120a and the second active material layer 120b generally include a positive electrode active material, a binder and a conductive agent, and the positive electrode active material mainly includes lithium cobalt oxide (LCO), nickel cobalt manganese ternary material (NCM) , nickel cobalt aluminum ternary material (NCA), nickel cobalt manganese aluminum quaternary material (NCMA), lithium iron phosphate (LFP), lithium manganese phosphate (LMP), lithium vanadium phosphate (LVP), lithium manganate (LMO), At least one of lithium-rich manganese bases.

The pole lug 200 welded on the pole piece body 100 of the positive pole piece 11 is a positive pole lug, and the material of the positive pole lug is also selected aluminum (Al) material, and the thickness of the positive pole lug is 0.1mm, and the width is 6mm, and the positive pole lug and the current collector 110 The length of the overlapping portion is 20 mm. The positive tab is welded to the welding area 111 in the groove 121 on the positive sheet 11 by laser welding.

The groove 121 is obtained mechanically. The width of the groove 121 is 10mm, the length is 25mm, and the depth of the groove is 0.05mm. 1/2 of the total length. The groove 121 is notched, the shape of the notch is trapezoidal, the width of the notch is 10mm, and the length is 2mm.

The appearance of the solder joints 112 is set to be circular, the diameter of the solder joints 112 is 0.8 mm, and the distance between adjacent solder joints 112 is 0.2 mm. The laser power is set to 30W, the pulse width is set to 0.02ms, and the surface protrusion of the solder spot 112 is 20 μm after the welding is completed. The number of solder joints 112 is 20, and the area of the raised part on at least half of the solder joints 112 accounts for more than 50% of the area of the solder joints 112 . The bulge of such a shape is relatively low overall, and the bulge area is relatively large, so it is not easy to pierce the separator, which improves the safety performance of the battery. Moreover, the welding tension reaches 30N, and the reliability of the pole piece 10 is relatively high.

An insulating adhesive layer 310 is attached to the surface of the positive tab after welding, and the insulating adhesive layer 310 has a width of 20 mm, a length of 30 mm, and a thickness of 0.012 mm. The insulating adhesive layer 310 completely covers part of the surface of the positive tab and the groove 121 . After the positive tab is electrically connected to the external circuit, the positive plate 11 of the battery can be formed.

The pole piece body 100 of the negative electrode piece 12 includes a current collector 110, a first active material layer 120a and a second active material layer 120b, wherein the current collector 110 is selected from nickel (Ni), copper (Cu) or nickel-plated copper (Ni—Cu) Made of alloy and other materials, the thickness of the current collector 110 is 0.008mm. The constituent materials of the first active material layer 120a and the second active material layer 120b generally include negative electrode active materials, binders and conductive agents, and the negative electrode active materials include graphite, mesocarbon microspheres, soft carbon, hard carbon, silicon materials, At least one of silicon-oxygen material, silicon-carbon material, and lithium titanate.

The pole lug 200 welded on the pole piece body 100 of the negative pole piece 12 is a negative pole lug, and the material of the negative pole lug is also selected materials such as nickel (Ni), copper (Cu) or copper-plated nickel (Ni—Cu) alloy, and the negative pole lug The thickness is 0.1 mm, the width is 6 mm, and the length of the overlapping portion of the negative tab and the current collector 110 is 20 mm. The negative tab is welded on the welding area 111 in the groove 121 on the negative electrode sheet 12 by means of laser welding.

An insulating adhesive layer 310 is pasted on the surface of the negative tab after welding, and the insulating adhesive layer 310 completely covers part of the surface of the negative tab and the groove 121 . The negative pole of the battery can be formed after the negative pole ear is electrically connected with the external circuit.

The present application provides a battery, including the above pole piece. The specific composition, structure and working principle of the pole piece have been introduced in detail in the above content, and will not be repeated here.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the application. scope.

Claims

A pole piece (10), characterized in that it includes a pole piece body (100) and a pole piece (200), and the pole piece body (100) includes a current collector (110) and two active material layers (120), The two active material layers (120) are respectively arranged on two opposite sides of the current collector (110);

At least one of the active material layers (120) has a groove (121), the bottom wall of the groove (121) is the current collector (110), and the tab (200) is arranged in the groove (121), and welded with the current collector (110) to form a solder joint (112);

The welding spot (112) is in a circular shape, and the diameter of the welding spot (112) is 0.03mm˜2mm.
The pole piece (10) according to claim 1, characterized in that, the two active material layers (120) comprise a first active material layer (120a) and a second active material layer (120b), and the first The active material layer (120a) and the second active material layer (120b) are respectively located on two opposite sides of the current collector (110);

The first active material layer (120a) has the groove (121), and the surface of the current collector (110) facing away from the groove (121) is provided with the second active material layer (120b), The projection of the groove (121) on the current collector (110) is located within the projection of the second active material layer (120b) on the current collector (110).
The pole piece (10) according to claim 1, characterized in that there are multiple welding spots (112), and each welding spot (112) is arranged at intervals, adjacent to the welding spots (112) The distance between them is 0.001 mm to 5 mm.
The pole piece (10) according to claim 1, characterized in that, each of the welding points (112) is arranged in a rectangular array or in a circular array.
The pole piece (10) according to claim 1, characterized in that at least part of the solder joints (112) are located on the surface of the tab (200) away from the current collector (110), and face away from the current collector (110). One side of the current collector (110) is raised to form a raised portion (113).
The pole piece (10) according to claim 5, characterized in that, the height of the raised portion (113) is equal to or less than 50% of the diameter D0 of the welding spot (112).
The pole piece (10) according to claim 1, characterized in that, there is a welding area (111) in the groove (121), and the welding point (112) is located in the welding area (111);

The width D1 of the welding area (111) is 50%-100% of the width D of the tab (200), and/or, the length L1 of the welding area (111) is between the tab (200) and 50%-100% of the length L of the overlapping portion of the current collector (110).
The pole piece (10) according to any one of claims 1-7, characterized in that, the thickness of the pole lug (200) is 0.01mm-0.5mm, and/or, the thickness of the pole lug (200) The width D is 1mm-12mm, and/or, the length of the tab (200) is 5mm-50mm.
The pole piece (10) according to claim 1, characterized in that, the thickness of the pole lug (200) is greater than or equal to the depth of the groove (121).
A battery, characterized by comprising the pole piece (10) according to any one of claims 1-9.