WO2023088433A1

WO2023088433A1 - Plate and battery

Info

Publication number: WO2023088433A1
Application number: PCT/CN2022/132903
Authority: WO
Inventors: 彭宁
Original assignee: 珠海冠宇电池股份有限公司
Priority date: 2021-11-18
Filing date: 2022-11-18
Publication date: 2023-05-25
Also published as: CN113964327A

Abstract

Provided in the present application are a plate and a battery. The plate comprises: a plate body and a tab, wherein the plate body comprises a current collector and active material layers, the current collector comprises two functional surfaces, which are arranged opposite each other, and the active material layers are respectively arranged on the two functional surfaces; a groove is formed in the active material layer on one functional surface of the current collector, and a groove bottom wall of the groove is the functional surface of the current collector; and the tab is soldered to the current collector in the groove to form soldering marks, and at least some of the soldering marks are located on a surface of the side of the tab facing away from the current collector, and protrudes towards the side facing away from the current collector. Thus, only part of the active material layer on one functional surface of the current collector is removed, and the active material layer on a back surface of the groove is reserved, so that the total amount of the removed active material layer can be reduced. Therefore, the plate and the battery provided in the present application can reserve more of the active material layers, thereby improving the energy density of the battery.

Description

pole piece and battery

This application claims the priority of the Chinese patent application with the application number 202111372461.8 and the application title "pole piece and battery" submitted to the China Patent Office on November 18, 2021, the entire contents of which are incorporated in this application by reference.

technical field

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

Background technique

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

In the related art, a pole piece may include a pole piece body and a tab. The pole piece body includes a current collector and an active material layer, and the active material layer is disposed on two opposite surfaces of the current collector. An empty foil area is provided on the pole piece body, and the active material layer in the empty foil area is removed to expose two opposite surfaces of the current collector in the empty foil area, and the tabs are welded on the current collector in the empty foil area.

However, the active material layer in the pole piece is removed more, which affects the energy density of the battery.

Contents of the invention

In view of the above problems, the embodiments of the present application provide a pole piece and a battery, which can retain more active material layers and increase the energy density of the battery.

In order to achieve the above purpose, the embodiment of the present application provides the following technical solutions:

The first aspect of the embodiments of the present application provides a pole piece, including: a pole piece body and a tab, the pole piece body includes a current collector, a first active material layer and a second active material layer, and the current collector includes a first active material layer oppositely arranged. a functional surface and a second functional surface, the first active material layer is disposed on the first functional surface, and the second active material layer is disposed on the second functional surface;

The first active material layer is provided with a groove, and the bottom wall of the groove is the first functional surface;

The tab is welded to the current collector in the groove to form a welding print, at least part of the solder print is located on the side of the tab away from the current collector, and protrudes toward the side away from the current collector to form a first protrusion.

The pole piece provided by the embodiment of the present application includes a pole piece body and a pole lug, and the pole piece is used to electrically connect the pole piece body with an external circuit. The current collector includes two functional surfaces facing each other, and active material layers are respectively arranged on the two functional surfaces. A groove is provided on one side of the pole piece body, the groove bottom wall of the groove is the functional surface of the current collector, and the groove is used for setting the pole lug. The tab is located in the groove, and the tab is welded to the current collector in the groove. In this way, only part of the active material layer on one of the functional surfaces of the current collector is removed to connect the tabs, while the active material layer on the side of the current collector away from the groove is retained. The total amount of removed active material layer can be reduced, thereby improving the energy density of the battery.

In a possible implementation manner, 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, along the thickness direction of the pole piece body, the solder print runs through the tab and the current collector; the solder print located on the side of the current collector away from the tab protrudes toward the side away from the tab to form a second protrusion rise, the second active material layer covers the second protrusion; or,

The welding print includes an outer edge part and a middle part, and the outer edge part is set outside the middle part; along the thickness direction of the pole piece body, the outer edge part runs through the tab and the current collector, and is located on the outer edge of the collector on the side away from the tab The part protrudes toward the side away from the tab to form a second protrusion, and the second active material layer covers the second protrusion.

In a possible implementation manner, the welding mark includes an outer edge part and a middle part, and the outer edge part is arranged outside the middle part;

Along the thickness direction of the pole piece body, the middle part passes through the tab, and the middle part is located in a partial area of the current collector close to the tab in the thickness direction.

In a possible implementation manner, along the thickness direction of the pole piece body, the solder print runs through the tab, and the solder print is located in a partial area of the current collector close to the tab in the thickness direction.

In a possible implementation manner, along the thickness direction of the pole piece body, the outer edge of the current collector on the side away from the tab is overlapped with the outer edge of the tab on the side away from the pole piece body.

In a possible implementation manner, the height of the second protrusion is less than or equal to the height of the first protrusion.

In a possible implementation, there are multiple welding marks, and the plurality of welding marks are arranged at intervals to form a welding area, and the shape of the welding marks on the side of the tab away from the pole piece body is spiral;

On the side of the lug away from the current collector:

The number of turns of the welded spiral is 1-10 turns;

And/or, the distance between any two adjacent solder marks is less than or equal to 5mm;

And/or, in each weld mark, the distance between the center of the helix of the weld mark and the outer edge of the outermost helix of the weld mark ranges from 0.05mm to 2.5mm;

And/or, the ratio of the width of the helix to the height of the protrusion of the helix is greater than 1 in any helix of the weld print;

And/or, in any helix of the welding print, the width of the helix is in the range of 0.01mm-0.2mm;

And/or, the height of the first protrusion is less than or equal to 0.1mm;

And/or, in each welding mark, the distance between any two adjacent turns of the helix is in the range of 0.01mm-3mm.

In a possible implementation manner, the depth of the groove ranges from 0.01mm to 0.2mm;

And/or, the length of the groove along the width direction of the pole piece body is in the range of 1mm-40mm;

And/or, the length of the groove along the length direction of the pole piece body is in the range of 1mm-30mm.

The second aspect of the embodiment of the present application provides a battery, including at least two pole pieces stacked on top of each other with opposite polarities, a separator is arranged between every two adjacent pole pieces,

At least one pole piece is the pole piece in the above first aspect.

In the battery provided in the embodiment of the present application, the battery includes a pole piece, and the pole piece includes a pole piece body and a tab, and the tab is used to electrically connect the pole piece body with an external circuit. The current collector includes two functional surfaces facing each other, and active material layers are respectively arranged on the two functional surfaces. A groove is provided on one side of the pole piece body, the groove bottom wall of the groove is the functional surface of the current collector, and the groove is used for setting the pole lug. The tab is located in the groove, and the tab is welded to the current collector in the groove. In this way, only part of the active material layer on one of the functional surfaces of the current collector is removed to connect the tabs, while the active material layer on the side of the current collector away from the groove is retained. The total amount of removed active material layer can be reduced, thereby improving the energy density of the battery.

In a possible implementation manner, the at least two pole pieces include a first pole piece and a second pole piece with opposite polarities;

The first pole piece includes a first tab, a first current collector, a first sub-active material layer, and a second sub-active material layer. The first current collector includes a first sub-functional surface and a second sub-functional surface that are oppositely arranged. A sub-active material layer is disposed on the first sub-functional surface, and a second sub-active material layer is disposed on the second sub-functional surface;

The first sub-active material layer is provided with a first groove, the groove bottom wall of the first groove is the first sub-functional surface; the first tab is electrically connected to the first sub-functional surface in the first groove;

The projection of the first groove on the first current collector is located within the projection of the second sub-active material layer on the first current collector.

In a possible implementation manner, a first protective layer is provided between the diaphragm adjacent to the first groove and the first tab; and/or, the diaphragm adjacent to the first groove and the adjacent A first protective layer is arranged between the second pole pieces of the diaphragm;

The projection of the first groove on the first current collector is located within the projection of the first protective layer on the first current collector.

In a possible implementation manner, the second pole piece includes a second tab, a second current collector, a third sub-active material layer, and a fourth sub-active material layer, and the second current collector includes a third sub-functional The surface and the fourth sub-functional surface, the third sub-active material layer is arranged on the third sub-functional surface, and the fourth sub-active material layer is arranged on the fourth sub-functional surface;

The third sub-active material layer is provided with a second groove, and the groove bottom wall of the second groove is a third sub-functional surface; the second tab is electrically connected to the third sub-functional surface in the second groove;

The projection of the second groove on the second current collector is located within the projection of the fourth sub-active material layer on the second current collector.

In a possible implementation manner, a second protective layer is provided between the diaphragm adjacent to the second groove and the second tab; and/or, the diaphragm adjacent to the second groove and the adjacent A second protective layer is arranged between the first pole pieces of the diaphragm;

The projection of the second groove on the second current collector is located within the projection of the second protective layer on the second current collector.

The structure of the present application as well as its other invention objectives and beneficial effects will be more clearly understood through the description of the preferred embodiments in conjunction with the accompanying drawings.

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 a top view of a pole piece provided by the embodiment of the present application;

Fig. 2 is the sectional view of B-B direction in Fig. 1;

Fig. 3 is a top view of a welding zone provided by an embodiment of the present application;

Fig. 4 is an enlarged structural schematic diagram of a spiral solder print provided by the embodiment of the present application;

Fig. 5 is A-A to sectional view in Fig. 4;

Fig. 6 is a 3D microscope top view of the solder print on the side of the current collector away from the tab provided in the embodiment of the present application;

Fig. 7 is a 3D microscope top view of a second protrusion provided in the embodiment of the present application;

Fig. 8 is a 3D microscope top view of another second protrusion provided in the embodiment of the present application;

Fig. 9 is a schematic structural diagram of a solder print arranged in a matrix provided by the embodiment of the present application;

Fig. 10 is a schematic structural diagram of another solder print arranged in a matrix provided by the embodiment of the present application;

FIG. 11 is a schematic structural diagram of a cell in a battery provided in an embodiment of the present application.

Explanation of reference signs:

100-pole piece;

110-the first pole piece;

120-the second pole piece;

200-diaphragm;

10- pole piece body;

11-collector;

12 - active material layer;

121 - groove;

1211 - first groove;

1212 - second groove;

20-pole ear;

21 - the first pole ear;

22 - the second pole ear;

30 - welding area;

31-welding print;

311 - helix;

312a - first protrusion;

312b - second protrusion;

40 - protective layer;

41 - first protective layer;

42 - Second protective layer.

Detailed ways

The pole piece may include a pole piece body and tabs, the pole piece body includes a current collector and an active material layer, and the active material layer is arranged on two opposite surfaces of the current collector. An empty foil area is provided on the pole piece body, and the active material layer in the empty foil area is removed to expose two opposite surfaces of the current collector in the empty foil area, and the tabs are welded on the current collector in the empty foil area.

However, only one surface of the current collector may be used when the current collector is connected to the tab. By setting the empty foil area to connect the tabs, it is necessary to remove the active material layers on the two opposite surfaces of the current collector, resulting in more active material layers being removed, which affects the energy density of the battery.

In view of the above technical problems, embodiments of the present application provide a pole piece and a battery. The pole piece includes a pole piece body and tabs, and the tabs are used to electrically connect the pole piece body with an external circuit. The current collector includes two functional surfaces facing each other, and active material layers are respectively arranged on the two functional surfaces. The active material layer on one of the functional surfaces of the current collector is provided with a groove, and the bottom wall of the groove is the functional surface of the current collector; the tab is welded to the current collector in the groove. In this way, only part of the active material layer on one of the functional surfaces of the current collector is removed to connect the tabs, while the active material layer on the back of the groove is retained. The total amount of removed active material layer can be reduced, thereby improving the energy density of the battery.

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.

As shown in FIGS. 1-2 , the embodiment of the present application provides a pole piece 100 that can be used in a battery. The pole piece 100 includes a pole piece body 10 and a pole lug 20 for electrically connecting the pole piece body 10 with an external circuit.

As shown in FIG. 3 , the tab 20 and the pole piece body 10 are welded to form a welding mark 31 .

When there are multiple solder marks 31 , the multiple solder marks 31 jointly form the soldering area 30 . Among them, a plurality of welding marks 31 are arranged at intervals in the welding area 30, and a single welding mark 31 is relatively small, so that the input energy required to form each welding mark 31 is relatively small, and avoid excessive heat and cause the pole piece body 10 to overheat. The phenomenon of welding or welding through ensures the performance of the pole piece 100 .

At least part of the solder marks 31 are located on the side of the lug 20 away from the pole piece body 10 , and protrude toward the side away from the pole piece body 10 . In this way, when the pole lug 20 and the pole piece body 10 are welded, welding can be performed from the side away from the pole piece body 10 from the pole piece 20 instead of welding from the side away from the pole piece body 10 away from the pole piece body 10, which can reduce the need for welding. The influence of the active material layer 12 on the side of the pole piece body 10 away from the tab 20 .

As shown in FIG. 4 , the shape of the welding mark 31 located on the side of the tab 20 away from the pole piece body 10 can be spiral, and the spiral welding mark 31 includes a multi-turn spiral line 311, and the spiral welding mark 31 includes One turn is a helix 311 . There is a distance between two adjacent turns of the helical wire 311 , which is conducive to heat dissipation during the welding process, and avoids over-welding or welding-through caused by heat accumulation.

The number of turns of the helix of the spiral solder print 31 is 1 turn to 10 turns. The number of turns of the helix of the welding mark 31 can be set to 1 turn, 2 turns, 3 turns, 4 turns, 5 turns, 8 turns or 10 turns according to the actual situation, which is not limited in this application. When the number of turns of the spiral welding mark 31 is greater than 10, the welding mark 31 is too large, and the energy input to form the welding mark 31 is relatively high, which affects the active material layer 12 at the welding area 30 .

Continuing as shown in FIG. 4 , in each spiral solder mark 31, the distance between any adjacent two turns of the helix 311 is L1, and the distance L1 between any adjacent two turns of the helix 311 ranges 0.01mm-3mm. For example, the distance L1 between any two adjacent turns of the helical wire 311 may be 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm or 3mm, etc., which is not limited in this embodiment. When the distance L1 between any two adjacent turns of the helix 311 is less than 0.01, the distance between any two adjacent turns of the helix 311 is too close, and the heat dissipation during the welding process is poor. When the distance L1 between any adjacent two turns of the helix 311 is greater than 3 mm, the distance between any adjacent two turns of the helix 311 is too large, and the effective welding area between the tab 20 and the pole piece body 10 is relatively small. Small, low welding strength.

In each spiral welding mark 31 , the distance between the spiral center of the welding mark 31 and the outer edge of the outermost helix 311 of the welding mark 31 may range from 0.05 mm to 2.5 mm. This distance is the distance from the center of the solder mark 31 to the outer edge of the solder mark 31 . For example, the distance between the spiral center of the welding mark 31 and the outer edge of the outermost helix 311 of the welding mark 31 can be 0.05mm, 0.25mm, 0.5mm, 1mm, 1.5mm or 2.5mm, etc. This is not limited. When the distance between the spiral center of the welding mark 31 and the outer edge of the outermost helix 311 of the welding mark 31 is less than 0.05 mm, the welding mark 31 is too small, and the distance between the tab 20 at the welding mark 31 and the pole piece body 10 If the indirect contact area is too small, effective welding tension cannot be formed, and the welding strength is low. When the distance between the spiral center of the welding mark 31 and the outer edge of the outermost helix 311 of the welding mark 31 is greater than 2.5mm, the welding mark 31 is too large, and the energy input to form the welding mark 31 is relatively high, which is harmful to the welding area. The active material layer 12 at 30 is affected.

As shown in Figure 2, the pole piece body 10 includes a current collector 11 and an active material layer 12, and the pole piece 100 can be a negative pole piece or a positive pole piece, which can be determined according to the specific selection of materials for the current collector 11 and each active material layer 12. Sure. For example, when the current collector 11 is aluminum foil and the material of the active material layer 12 is a positive electrode active material such as a ternary material or lithium iron phosphate, the pole sheet 100 is a positive electrode sheet; when the current collector 11 is copper foil, the material of the active material layer 12 When it is a negative electrode active material such as graphite or silicon base, the pole piece 100 is a negative pole piece.

Wherein, the current collector 11 includes two opposite functional surfaces, and the active material layer 12 is respectively disposed on the two functional surfaces. The functional surfaces of the current collector 11 refer to the largest and opposite surfaces of the current collector 11 for coating the active material layer 12 . The active material layer 12 in the pole piece 100 of the present application may be coated on only one functional surface of the current collector 11 , or coated on both functional surfaces of the current collector 11 at the same time.

As shown in FIGS. 2 and 3 , the active material layer 12 on one of the functional surfaces of the current collector 11 is partially removed to form a groove 121 to expose part of the functional surface, and the exposed functional surface is used for contact with the tab. 20 electrical connection. In this way, only the active material layer 12 on one of the functional surfaces of the current collector 11 is removed to connect the tab 20, and the active material layer 12 on the side of the current collector 11 away from the groove 121 and facing the groove 121 is retained. . The total amount of the removed active material layer 12 can be reduced, thereby increasing the energy density of the battery.

As shown in FIG. 3 , the groove 121 may be close to an edge in the width direction of the pole piece body 10 , and a side of the groove 121 close to the edge is open. That is, there is no active material layer 12 on the outer side of the groove 121 close to the edge, and the active material layer 12 is disposed on the outer side of the groove 121 away from the edge. Along the width direction of the pole piece body 10 , the length of the groove 121 is smaller than the length of the current collector 11 . In addition, the outer sides of both ends of the groove 121 along the length direction of the pole piece body 10 may be provided with active material layers 12 .

It should be noted that the X direction in FIG. 1, that is, the length direction of the pole piece 100, is also the length direction of the pole piece body 10 and the current collector 11; the Y direction in FIG. 1, that is, the width direction of the pole piece 100, is also the length direction of the pole piece 100. The width direction of the sheet body 10 and the current collector 11 . The width direction and length direction in the embodiments of the present application are only for the convenience of description, and do not imply any limitation to any size. For example, width may be greater than, less than, or equal to length.

Specifically, in one pole piece 100, the two functional surfaces of the current collector 11 can be respectively the first functional surface and the second functional surface, and the active material layers can be respectively the first active material layer and the second active material layer. An active material layer is arranged on the first functional surface, and a second active material layer is arranged on the second functional surface. A groove 121 is disposed on the first active material layer, and the bottom wall of the groove 121 is a first functional surface. The second active material layer facing the groove 121 is not removed but remains. At this time, the projection of the groove 121 on the current collector 11 is located within the projection of the second active material layer on the current collector 11 . Therefore, the total amount of the removed second active material layer can be reduced, thereby improving the energy density of the battery.

Wherein, the groove 121 may be formed by removing the corresponding part of the active material layer 12 by cleaning to expose the current collector 11 . The cleaning method may be laser cleaning, mechanical cleaning, or styrofoam cleaning, and the application does not limit the cleaning method.

In some embodiments, as shown in FIG. 2 , the side of the tab 20 away from the current collector 11 can be covered with a protective layer 40 , the protective layer 40 plays a role in fixing the tab 20 , and the protective layer 40 can avoid the groove 121 and the pole The burrs on the ears 20 pierce the membrane in the cell adjacent to the groove 121 . Wherein, the protection layer 40 completely covers the groove 121 .

In some embodiments, the depth of the groove 121 ranges from 0.01 mm to 0.2 mm. For example, the depth of the groove 121 may be 0.01 mm, 0.03 mm, 0.04 mm, 0.05 mm, 0.07 mm, 0.1 mm or 0.2 mm, which is not limited in this embodiment of the present application. When the depth of the groove 121 is less than 0.01mm, the active material layer 12 is thinner, and the energy density of the battery is lower. When the depth of the groove 121 is greater than 0.2 mm, the active material layer 12 is thicker, resulting in a greater thickness of the pole piece body 10 .

The length of the groove 121 along the width direction of the pole piece body 10 ranges from 1 mm to 40 mm. For example, the length may be 1 mm, 2 mm, 5 mm, 10 mm, 15 mm, 20 mm, 30 mm, or 40 mm, etc., which is not limited in this embodiment of the present application. Along the width of the pole piece body 10, when the length of the groove 121 is less than 1mm, the groove 121 is smaller, and the exposed functional surface area of the current collector 11 is smaller, resulting in a weaker connection between the tab 20 and the current collector 11. Low. When the length of the groove 121 is greater than 40mm, the groove 121 is larger, and the active material layer 12 is removed more, which has a great impact on the energy density of the battery.

The length of the groove 121 along the length direction of the pole piece body 10 ranges from 1 mm to 30 mm. For example, the length may be 1 mm, 2 mm, 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, or 30 mm, etc., which is not limited in this embodiment of the present application. The principle is similar to the length of the groove 121 along the width direction of the pole piece body 10 , and will not be repeated here.

In some embodiments, the tab 20 and the pole piece body 10 may be connected by ultrasonic welding. In ultrasonic welding, it is necessary to contact the horn for ultrasonic welding with the side of the current collector 11 away from the tab 20 , and perform pressurized vibration to weld the tab 20 and the current collector 11 together. At this time, it is necessary to clean off the active material layers 12 on the two functional surfaces where the current collector 11 and the tab 20 are connected, resulting in a low energy density of the pole piece 100 . In addition, during the welding process, the welding head of the ultrasonic welding will be worn and needs to be replaced regularly, which increases the workload of the staff. The wear of the welding head may easily lead to the problem of virtual welding or over-welding between the tab 20 and the current collector 11, thereby affecting the performance of the battery. Moreover, ultrasonic welding will form relatively sharp needle-shaped welding protrusions. If the pole piece 100 is assembled into a battery, it will easily pierce the diaphragm adjacent to the needle-shaped welding protrusions, causing a short circuit between the positive electrode sheet and the negative electrode sheet, thereby possibly lead to safety incidents.

In this embodiment, the tab 20 and the current collector 11 may be connected by laser welding. Laser welding does not require the use of a welding head, which can effectively avoid the above-mentioned problems of ultrasonic welding. In the laser welding process, laser welding is to irradiate laser light on the tab 20 from the side of the tab 20 away from the current collector 11 to weld between the tab 20 and the current collector 11 . After the laser welding is completed, a plurality of welding marks 31 arranged at intervals will be formed at the welding place of the tab 20 and the current collector 11 , and the plurality of welding marks 31 together form the welding area 30 .

Laser welding is irradiated from the side of the tab 20 facing away from the current collector 11 , without cleaning the active material layer 12 on the side of the current collector 11 away from the tab 20 , and the energy density of the pole piece 100 is relatively high.

As shown in FIG. 4 and FIG. 5 , the solder mark 31 on the side of the tab 20 away from the current collector 11 protrudes toward the side away from the current collector 11 , thereby forming a first protrusion 312 a. The shape of the first protrusion 312a may be a spiral. On the side of the tab 20 facing away from the current collector 11 , each helix 311 of the solder print 31 together forms a first protrusion 312 a. There is a planar structure between two adjacent helixes 311, and the planar structure is the surface of the tab 20 without the helix 311, and the tab 20 between the two adjacent helixes 311 is conducive to the formation of the solder print 31. heat dissipation.

In some examples, along the thickness direction of the pole piece body 10 , the solder print 31 runs through the tab 20 , and the solder print 31 is located in a partial area of the current collector 11 close to the tab 20 in the thickness direction. The laser penetration is greater than the thickness of the tab 20 and smaller than the sum of the thicknesses of the tab 20 and the current collector 11 . At this time, the solder mark 31 is formed on the side of the tab 20 away from the current collector 11, and the surface of the current collector 11 away from the side of the tab 20 does not form the solder mark 31, and the surface of the current collector 11 away from the side of the tab 20 for the plane. In this way, the solder marks 31 have less influence on the active material layer 12 on the side of the current collector 11 away from the tab 20 .

In some other examples, as shown in FIGS. 6-8 , along the thickness direction of the pole piece body 10 , the solder print 31 runs through the tab 20 and the current collector 11 . Because there is heat accumulation in the welding process, as the welding progresses, the laser penetration depth will gradually increase. Solder marks 31 are also formed on one side. At this time, solder marks 31 can be observed on the side of the tab 20 away from the current collector 11 and the side of the current collector 11 away from the tab 20 . Wherein, the solder mark 31 located on the side of the current collector 11 away from the tab 20 is covered by the active material layer 12 , which can reduce the impact of the solder mark 31 on the separator on this side. The solder mark 31 located on the side of the current collector 11 away from the tab 20 protrudes toward the side away from the tab 20 , thereby forming a second protrusion 312 b.

In some other examples, in the same solder mark 31, part of the solder mark 31 penetrates the tab 20 and the current collector 11; another part of the solder print 31 penetrates the tab 20 and is located close to the tab in the thickness direction of the current collector 11 20 within a portion of the area. For example, the solder print 31 includes an outer edge portion and a middle portion, and the outer edge portion is arranged around the outer side of the middle portion. Along the thickness direction of the pole piece body, the outer edge passes through the tab 20 and the current collector 11 , and the outer edge of the current collector 11 on the side away from the tab 20 protrudes toward the side away from the tab 20 . During the welding process, the current collector 11 is slightly deformed, and the compression effect is not good, resulting in a gradual decrease in the defocus amount of the laser welding, and a welding mark 31 is formed on the side of the current collector 11 away from the tab 20 at the welding end. At this time, the outer edge of the solder mark 31 can be observed on the surface of the current collector 11 facing away from the tab 20 . The outer edge of the current collector 11 on the side away from the tab 20 protrudes toward the side away from the tab 20 , thereby forming a second protrusion 312 b. Wherein, the outer edge portion of the current collector 11 on the side away from the tab 20 is covered by the active material layer 12 , which can reduce the influence of the outer edge portion on the separator on this side.

In addition, along the thickness direction of the pole piece body 10 , the middle portion passes through the tab 20 , and the middle portion is located in a partial area of the current collector 11 close to the tab 20 in the thickness direction. At this time, the middle portion of the solder mark 31 cannot be observed on the surface of the current collector 11 facing away from the tab 20 .

It should be noted that, in one solder mark 31 , all the outer edges may penetrate through the tab 20 and the current collector 11 . At this time, along the thickness direction of the pole piece body 10 , the outer edge of the current collector 11 away from the tab 20 is overlapped with the outer edge of the tab 20 away from the pole piece body 10 .

Alternatively, part of the outer edge may pass through the tab 20 and the current collector 11 .

In the embodiment of forming the first protrusion 312a and the second protrusion 312b at the same time, the welding mark 31 forms the first protrusion 312a on the side of the tab 20 away from the current collector 11, and the shape of the first protrusion 312a is a spiral shape. The solder print 31 forms a second protrusion 312b on the surface of the current collector 11 facing away from the tab 20 . At this time, the welding tension between the tab 20 and the current collector 11 is relatively high, and the welding reliability is high.

Wherein, the first protrusion 312 a and the second protrusion 312 b may be disposed opposite to each other along the thickness direction of the current collector 11 . The projection of the second protrusion 312b on the current collector 11 is located within the projection of the first protrusion 312a on the current collector 11 . As shown in FIG. 7 and FIG. 8 , the second protrusion 312b may be disposed opposite to the outer helical line of the first protrusion 312a (corresponding to an implementation manner of the outer edge portion). The outer helix may be the outermost helix, or the outer helix may be any one of the outermost helix and the innermost helix 311 , such as the second outer helix. At this time, as shown in FIG. 7, the shape of the second protrusion 312b is close to a ring; or, as shown in FIG. 8, the shape of the second protrusion 312b is close to a ring, and there are multiple There is no raised breakpoint, at which breakpoint, the solder print 31 does not penetrate through the current collector 11 and is flat, that is, the breakpoint is a planar structure of the current collector 11 . In some other examples, the second protrusion 312b may also be formed at other positions of the solder print 31 , for example, the second protrusion 312b may also be in a spiral shape, which is not limited in the present application.

In some embodiments, the height of the second protrusion 312b is less than or equal to the height of the first protrusion 312a. In this way, the second protrusion 312b has less influence on the active material layer 12 on the side of the current collector 11 away from the tab 20 .

As shown in FIG. 5 , on the side of the tab 20 facing away from the current collector 11 , in any helix 311 of the welding mark 31 , the height of the first protrusion 312a is H, and the width of the first protrusion 312a is W. The ratio of the width W of the first protrusion 312 a to the height H of the first protrusion 312 a is greater than or equal to one. For example, the ratio of the width W of the first protrusion 312a to the height H of the first protrusion 312a is 1, 1.2, 1.5 or 2, etc., which is not limited in this embodiment. When the ratio of the width W of the first protrusion 312a to the height H of the first protrusion 312a is less than 1, the shape of the first protrusion 312a is relatively sharp, so that the first protrusion 312a is easy to puncture in the battery. Adjacent separators affect battery safety.

On the side of the tab 20 facing away from the current collector 11 , in any helical line 311 of the welding mark 31 , the width W of the first protrusion 312 a ranges from 0.01 mm to 0.2 mm. For example, the width W of the first protrusion may be 0.01 mm, 0.05 mm, 0.1 mm, 0.15 mm or 0.2 mm, etc., which is not limited in this embodiment. When the width W of the first protrusion is less than 0.01 mm, the welding area between the tab 20 at the first protrusion 312a and the pole piece body 10 is small, and the welding strength is low. When the width W of the first protrusion is greater than 0.2 mm, the energy input when forming the first protrusion 312 a is relatively high, which affects the active material layer 12 near the soldering mark 31 .

On the side of the tab 20 facing away from the current collector 11 , in any helix 311 of the welding mark 31 , the height H of the first protrusion 312 a is less than or equal to 0.1 mm. For example, the height H of the first protrusion 312 a may be 0.01 mm, 0.03 mm, 0.05 mm, 0.07 mm, 0.09 mm or 0.1 mm, etc., which is not limited in this embodiment. When the height H of the first protrusion 312a is greater than 0.1mm, the first protrusion 312a is relatively high, and the first protrusion 312a is easy to pierce the adjacent diaphragm in the battery, causing the positive and negative poles of the battery to be short-circuited. .

On the side of the current collector 11 away from the tab 20 , the size parameter of the second protrusion 312 b can be set with reference to the range of the size parameter of the first protrusion 312 a. For example, in any circle of the helix 311, the ratio of the width of the second protrusion 312b to the height of the second protrusion 312b is greater than or equal to 1; the height of the second protrusion 312b is less than or equal to 0.1mm; the second protrusion 312b The width range is 0.01mm-0.2mm.

As shown in Figures 9 and 10, a plurality of welding marks 31 are arranged on the welding area 30, and the distance between the outermost helixes 311 of any two adjacent spiral welding marks 31 (L2 in Figure 9 ) can be less than or equal to 5mm. This distance is the distance between two solder marks 31 . For example, the distance L2 between two adjacent solder marks 31 may be 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm, etc., which is not limited in this embodiment. When the distance L2 between two adjacent solder marks 31 is greater than 5 mm, the solder marks 31 in the welding area 30 are scattered, the number of solder marks 31 is small, and the effective connection area between the tab 20 and the current collector 11 is small , the connection strength between the tab 20 and the current collector 11 is low.

As shown in FIG. 9 , a plurality of solder prints 31 can be arranged in a matrix. Wherein, a plurality of solder prints 31 may be arranged in a matrix of multiple rows and multiple columns. The number of rows in the matrix can be 2 rows, 3 rows, 4 rows, 5 rows or 10 rows, etc., which is not limited in this application. The number of columns in the matrix can be 2 rows, 3 rows, 4 rows, 5 rows or 10 rows, etc., which is not limited in this application. As shown in FIG. 9 , the matrix can be arranged into a matrix of 10 rows*4 columns, and there are totally 40 spiral solder marks 31 in the matrix. The matrix arrangement is more beautiful and tidy, and the distribution of each welding mark 31 is more even, so that the welding uniformity of the welding area 30 is better.

As shown in FIG. 10 , the plurality of solder marks 31 can also be arranged in at least two matrices, and the plurality of matrices can be arranged at intervals along the width direction or the length direction of the pole piece 100 . For example, the number of matrices formed by each solder print 31 may be 2, 3 or 4, and the present application does not limit the number of matrices.

Wherein, the number of solder marks 31 in each matrix may be the same or different. There is a gap between two adjacent matrices. As shown in Figure 10, the number of matrices is 3, wherein the solder prints 31 in one matrix are arranged in 3 rows*4 columns, the number of solder prints 31 in one matrix is 12, and the solder prints 31 in three matrices The total is 36.

Exemplarily, when forming a matrix soldering mark 31 as shown in Figure 9, first put the tab 20 into the groove 121, and press the tab 20 with a clamp; then perform laser welding to form a plurality of spiral soldering marks 31 . Wherein, the distance between the spiral center of the welding mark 31 and the outer edge of the outermost helix 311 of the welding mark 31 is 0.25mm, and the distance between two adjacent welding marks 31 is 0.5mm, and the first protrusion 312a (In one helix 311 ) the width W is 0.05 mm, and the number of helixes 311 is four. The laser is continuously welded on the surface of the lug 20, and the welding time for forming a single welding mark 31 is 0.05s. A total of 10*4 welding marks 31 are formed, and the area of the welding zone 30 is 3.5mm*9.5mm.

In addition, this embodiment also provides a battery, which may include at least two pole pieces 100 stacked on top of each other with opposite polarities, and a separator 200 is arranged between every two adjacent pole pieces 100, and the separator 200 is used to prevent The pole pieces 100 of opposite polarity come into contact causing a short circuit of the battery. Wherein at least one pole piece 100 is the pole piece 100 in the above embodiment.

In this embodiment, as shown in FIG. 11 , at least two pole pieces 100 include a first pole piece 110 and a second pole piece 120 with opposite polarities. The first pole piece 110 can be a positive pole piece or a negative pole piece. The diode sheet 120 can be a negative electrode sheet or a positive electrode sheet.

In some embodiments, the first pole piece 110 includes a first tab 21, a first current collector, the active material layer 12 of the first pole piece includes a first sub-active material layer and a second sub-active material layer, and the first current collector The functional surface includes a first sub-functional surface and a second sub-functional surface oppositely arranged. The first sub-active material layer is arranged on the first sub-functional surface, and the second sub-active material layer is arranged on the second sub-functional surface; the first sub-active material layer is provided with a first groove 1211, and the first groove 1211 The bottom wall of the groove is the first sub-functional surface; the first tab 21 is electrically connected to the first sub-functional surface in the first groove 1211; the projection of the first groove 1211 on the first current collector is located at the second The sub-active material layer is within the projection on the first current collector. A portion of the second sub-active material layer facing the first groove 1211 is in contact with the diaphragm 200 . In this way, when the first groove 1211 is formed, only part of the first sub-active material layer is removed, and the second sub-active material layer on the back of the first groove 1211 is retained, so as to increase the energy density of the battery.

In some examples, a first protective layer 41 is disposed between the diaphragm 200 adjacent to the first groove 1211 and the first tab 21 . In this way, direct contact between the first tab 21 and the diaphragm 200 adjacent to the first groove 1211 can be avoided, and the burrs (formed by welding marks 31) on the first tab 21 can be avoided from piercing the diaphragm 200, thereby improving the safety of the battery. sex. Wherein, the first protective layer 41 may be provided on the surface of the diaphragm 200 facing the first groove 1211 , or the first protective layer 41 may be provided on the surface of the first tab 21 facing the diaphragm 200 .

In some other examples, the first protective layer 41 is disposed between the diaphragm 200 adjacent to the first groove 1211 and the second pole piece 120 adjacent to the diaphragm 200 . In this way, direct contact between the second pole piece 120 adjacent to the diaphragm 200 and the diaphragm 200 can be avoided, and after the diaphragm 200 is pierced by burrs, the burrs directly contact the second pole piece 120 to cause a battery short circuit, thereby Improve battery safety. Wherein, the first protective layer 41 can be arranged on the side of the diaphragm 200 facing the second pole piece 120 , or the first protective layer 41 can be arranged on the side of the second pole piece 120 facing the diaphragm 200 .

In some other examples, between the diaphragm 200 adjacent to the first groove 1211, and between the first tab 21; and the diaphragm 200 adjacent to the first groove 1211, and the second pole adjacent to the diaphragm 200 A first protective layer 41 is disposed between the sheets 120 . That is, two first protective layers 41 can be provided to further improve the safety of the battery.

The projection of the first groove 1211 on the first current collector is located within the projection of the first protective layer 41 on the first current collector. In this way, the first protective layer 41 can cover the first groove 1211 , which can prevent the burrs formed on the first groove 1211 and the first tab 21 from piercing the separator 200 and causing a short circuit of the battery.

In some embodiments, the second pole piece 120 includes a second tab 22 and a second current collector, and the active material layer 12 in the second pole piece 120 includes a third sub-active material layer and a fourth sub-active material layer. The functional surface of the current collector includes a third sub-functional surface and a fourth sub-functional surface opposite to each other. Wherein, the third sub-active material layer is disposed on the third sub-functional surface, and the fourth sub-active material layer is disposed on the fourth sub-functional surface. A second groove is arranged on the third sub-active material layer, and the bottom wall of the second groove is the third sub-functional surface. The second tab is electrically connected to the third sub-functional surface in the second groove. The projection of the second groove on the second current collector is located within the projection of the fourth sub-active material layer on the second current collector. A portion of the fourth sub-active material layer opposite to the second groove 1212 is in contact with the adjacent membrane 200 . In this way, when the second groove 1212 is formed, only part of the third sub-active material layer is removed, and the fourth sub-active material layer on the back of the second groove 1212 is retained, so as to increase the energy density of the battery.

In some examples, a second protection layer 42 is disposed between the diaphragm 200 adjacent to the second groove 1212 and the second tab 22 . In some other examples, the second protective layer 42 is disposed between the diaphragm 200 adjacent to the second groove 1212 and the first pole piece 110 adjacent to the diaphragm 200 . In some other examples, between the diaphragm 200 adjacent to the second groove 1212, and between the second tab 22; and the diaphragm 200 adjacent to the second groove 1212, and the first pole adjacent to the diaphragm 200 A second protective layer 42 is disposed between the sheets 110 . In this way, the safety of the battery can be improved, and its principle is similar to that of the first protective layer 41 , which will not be repeated here.

The projection of the second groove 1212 on the second current collector is located within the projection of the second protective layer 42 on the second current collector. In this way, the second protective layer 42 can cover the second groove 1212 , which can prevent the burrs formed on the second groove 1212 and the second tab 22 from piercing the separator 200 and causing a short circuit of the battery.

Specifically, the first pole piece 110 , the second pole piece 120 and the separator 200 can form a cell in a battery. The battery cell refers to the electrochemical cell installed inside the battery with positive and negative electrodes. The battery cell is generally not used directly. After the battery cell and the protection circuit are installed together in the battery case, it can be used for charging/ Discharged battery. Since the cell is the power storage part of the battery, the quality of the cell directly determines the quality of the battery.

The battery cell can be a wound battery cell or a laminated battery cell.

In some examples, as shown in FIG. 11 , the wound cell includes a first pole piece 110 and a second pole piece 120 . During the winding process, the first pole piece 110 , the separator 200 and the second pole piece 120 are wound in the same direction from the winding head and finally form a wound battery core.

In other examples, the laminated battery cell includes a plurality of first pole pieces 110 and a plurality of second pole pieces 120, and the first pole pieces 110 and the second pole pieces 120 are alternately stacked in the same direction during processing, and at the same time A diaphragm 200 is disposed between two adjacent first pole pieces 110 and second pole pieces 120 , and finally laminated to form a laminated battery cell.

It should be noted here that the numerical values and numerical ranges involved in the embodiments of the present application are approximate values, and there may be a certain range of errors due to the influence of the manufacturing process, and those skilled in the art may consider these errors to be negligible.

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 present application. scope.

Claims

A pole piece, characterized in that it includes: a pole piece body and a tab, the pole piece body includes a current collector, a first active material layer and a second active material layer, and the current collector includes a first function oppositely arranged a surface and a second functional surface, the first active material layer is disposed on the first functional surface, and the second active material layer is disposed on the second functional surface;

The first active material layer is provided with a groove, and the groove bottom wall of the groove is the first functional surface;

The tab is welded to the current collector in the groove to form a weld print, at least part of the solder print is located on the side of the tab away from the current collector, and faces away from the current collector. One side of the fluid protrudes to form a first protrusion.
The pole piece according to claim 1, wherein the projection of the groove on the current collector is located within the projection of the second active material layer on the current collector.
The pole piece according to claim 1, characterized in that, along the thickness direction of the pole piece body, the welding print runs through the tab and the current collector; The welding mark on the side protrudes toward the side away from the tab to form a second protrusion, and the second active material layer covers the second protrusion; or,

The solder print includes an outer edge portion and a middle portion, and the outer edge portion is arranged around the outer side of the middle portion; along the thickness direction of the pole piece body, the outer edge portion runs through the tab and the A current collector, the outer edge of the current collector on the side away from the tab protrudes toward the side away from the tab to form a second protrusion, and the second active material layer covers the second raised.
The pole piece according to claim 1, characterized in that, the solder mark includes an outer edge portion and a middle portion, and the outer edge portion is arranged around the outer side of the middle portion;

Along the thickness direction of the pole piece body, the middle portion passes through the tab, and the middle portion is located in a partial area of the current collector close to the tab in the thickness direction.
The pole piece according to claim 1, characterized in that, along the thickness direction of the pole piece body, the welding mark runs through the tab, and the welding mark is located near the current collector in the thickness direction Part of the area of the ear.
The pole piece according to claim 4, characterized in that, along the thickness direction of the pole piece body, the outer edge portion of the current collector on the side away from the tab is the same as the distance from the tab. The outer edges on one side of the pole piece body are overlapped.
The pole piece according to claim 3, wherein the height of the second protrusion is less than or equal to the height of the first protrusion.
The pole piece according to any one of claims 1-7, characterized in that there are a plurality of said solder marks, and a plurality of said solder marks are arranged at intervals to form a welding area, located on the side of the pole ear away from the pole The shape of the solder print on one side of the chip body is spiral;

On the side of the tab away from the current collector:

The number of turns of the welded spiral is 1-10 turns;

And/or, the distance between any two adjacent solder marks is less than or equal to 5mm;

And/or, in each of the welding marks, the distance between the spiral center of the welding mark and the outer edge of the outermost helix of the welding mark ranges from 0.05mm to 2.5mm;

And/or, in any helix of the welding print, the ratio of the width of the helix to the height of the protrusion of the helix is greater than 1;

And/or, in any circle of the helix of the welding print, the width of the helix is in the range of 0.01mm-0.2mm;

And/or, the height of the first protrusion is less than or equal to 0.1mm;

And/or, in each of the welding marks, the distance between any two adjacent turns of the helix is in the range of 0.01mm-3mm.
The pole piece according to any one of claims 1-7, characterized in that, the depth of the groove ranges from 0.01mm to 0.2mm;

And/or, the length of the groove along the width direction of the pole piece body ranges from 1 mm to 40 mm;

And/or, the length of the groove along the length direction of the pole piece body is in the range of 1mm-30mm.
A battery, characterized in that it includes at least two pole pieces stacked on top of each other with opposite polarities, a diaphragm is arranged between every two adjacent pole pieces,

At least one pole piece is the pole piece according to any one of claims 1-9.
The battery of claim 10, wherein at least two of said pole pieces comprise a first pole piece and a second pole piece of opposite polarity;

The first pole piece includes a first tab, a first current collector, a first sub-active material layer and a second sub-active material layer, and the first current collector includes a first sub-functional surface and a second sub-functional surface oppositely arranged. A functional surface, the first sub-active material layer is disposed on the first sub-functional surface, and the second sub-active material layer is disposed on the second sub-functional surface;

The first sub-active material layer is provided with a first groove, and the groove bottom wall of the first groove is the first sub-functional surface; The first sub-function surface is electrically connected;

The projection of the first groove on the first current collector is located within the projection of the second sub-active material layer on the first current collector.
The battery according to claim 11, wherein a first protective layer is provided between the diaphragm adjacent to the first groove and the first tab; and/or, adjacent to the first tab A first protective layer is provided between the diaphragm of the first groove and the second pole piece adjacent to the diaphragm;

The projection of the first groove on the first current collector is located within the projection of the first protective layer on the first current collector.
The battery according to claim 11 or 12, wherein the second pole piece comprises a second tab, a second current collector, a third sub-active material layer and a fourth sub-active material layer, and the second The current collector includes a third sub-functional surface and a fourth sub-functional surface oppositely arranged, the third sub-active material layer is disposed on the third sub-functional surface, and the fourth sub-active material layer is disposed on the first sub-functional surface. On the surface of the four sub-functions;

The third sub-active material layer is provided with a second groove, and the groove bottom wall of the second groove is the third sub-functional surface; The surface electrical connection of the third sub-function;

The projection of the second groove on the second current collector is located within the projection of the fourth sub-active material layer on the second current collector.
The battery according to claim 13, wherein a second protective layer is provided between the diaphragm adjacent to the second groove and the second tab; and/or, adjacent to the second tab A second protective layer is provided between the diaphragm of the second groove and the first pole piece adjacent to the diaphragm;

The projection of the second groove on the second current collector is located within the projection of the second protective layer on the second current collector.