CN113964327A - Pole piece and battery - Google Patents

Abstract

The application provides a pole piece and battery, the pole piece includes: the pole piece body comprises a current collector and an active substance layer, the current collector comprises two functional surfaces which are oppositely arranged, and the active substance layer is 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 current collector welding in utmost point ear and the recess forms the seal of welding, and at least part welds the seal and is located the face that deviates from current collector one side of utmost point ear, and the orientation is deviated from one side arch of current collector. In this way, only a part of the active material layer on one of the functional surfaces of the current collector is removed, and the active material layer on the back of the groove is retained, so that the total amount of the removed active material layer can be reduced. Therefore, the pole piece and the battery provided by the application can reserve more active substance layers and improve the energy density of the battery.

Description

pole piece and battery

technical field

The present application relates to the technical field of batteries, and 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 industries such as digital electronic products and electric vehicles.

In the related art, a pole piece may include a pole piece body and a pole 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. The pole piece body is provided with an empty foil area, 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 above-mentioned pole piece is largely removed, which affects the energy density of the battery.

SUMMARY 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 improve the energy density of the battery.

In order to achieve the above purpose, the embodiments of the present application provide the following technical solutions:

A first aspect of the embodiments of the present application provides a pole piece, comprising: a pole piece body and a pole lug, the pole piece body includes a current collector, a first active material layer, and a second active material layer, and the current collector includes first oppositely disposed first material layers. a functional surface and a second functional surface, the first active material layer is arranged on the first functional surface, and the second active material layer is arranged 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 tabs are welded with the current collectors in the grooves to form welding marks, and at least part of the welding marks are located on the side of the tabs facing away from the current collectors, and protrude toward the side away from the current collectors to form first protrusions.

In the pole piece provided in the embodiment of the present application, the pole piece includes a pole piece body and a pole lug, and the pole lug is used to electrically connect the pole piece body with an external circuit. The current collector includes two oppositely arranged functional surfaces, and the active material layers are respectively arranged on the two functional surfaces. One side surface of the pole piece body is provided with a groove, the bottom wall of the groove is the functional surface of the current collector, and the groove is used for arranging the pole ears. The tab is located in the groove, and the tab is welded with 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, and the active material layer on the side of the current collector away from the groove is retained. The total amount of active material layers removed can be reduced, thereby increasing 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 on the side of the current collector away from the electrode tab protrudes toward the side away from the electrode tab to form a second protrusion starting, the second active material layer covers the second protrusion; or,

The welding mark includes an outer edge part and a middle part, and the outer edge part is arranged on the outer side of the middle part; along the thickness direction of the pole piece body, the outer edge part penetrates the pole ear and the current collector, and is located at the outer edge of the collector away from the pole ear side The second protrusion is formed by the protrusion facing the side away from the tab, and the second active material layer covers the second protrusion.

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

Along the thickness direction of the pole piece body, the middle portion penetrates through the electrode tab, and the middle portion is located in a partial region of the current collector close to the electrode tab in the thickness direction.

In a possible implementation manner, along the thickness direction of the pole piece body, the solder print penetrates the electrode tab, and the solder print is located in a partial region of the current collector close to the electrode 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 pole tab is overlapped with the outer edge of the pole 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 manner, there are a plurality of solder prints, the plurality of solder prints are arranged at intervals and form a welding area, and the shape of the solder prints located on the side of the tab away from the pole piece body is spiral;

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

The number of turns of the soldered spiral wire is 1 turn to 10 turns;

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

And/or, in each solder print, the distance from the center of the spiral of the solder print to the outer edge of the outermost spiral of the solder print ranges from 0.05mm to 2.5mm;

And/or, in any circle of the helix of the solder printing, the ratio of the width of the helix to the height of the helix is greater than 1;

And/or, in any circle of the spiral line of the solder printing, the width of the spiral line 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 solder print, the distance between any two adjacent spirals ranges from 0.01mm to 3mm.

In a possible implementation, the groove 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 1mm to 40mm;

And/or, the length of the groove along the length direction of the pole piece body ranges from 1 mm to 30 mm.

A second aspect of the embodiments of the present application provides a battery, comprising at least two pole pieces stacked on each other with opposite polarities, and a separator is arranged between each adjacent two pole pieces,

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

In the battery provided by the embodiment of the present application, the battery includes a pole piece, and the pole piece includes a pole piece body and a pole lug, and the pole lug is used to electrically connect the pole piece body with an external circuit. The current collector includes two oppositely arranged functional surfaces, and the active material layers are respectively arranged on the two functional surfaces. One side surface of the pole piece body is provided with a groove, the bottom wall of the groove is the functional surface of the current collector, and the groove is used for arranging the pole ears. The tab is located in the groove, and the tab is welded with 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, and the active material layer on the side of the current collector away from the groove is retained. The total amount of active material layers removed can be reduced, thereby increasing the energy density of the battery.

In a possible implementation, 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 arranged oppositely, the first sub-functional surface A sub-active material layer is arranged on the first sub-functional surface, and a 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, and the 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 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-function arranged oppositely surface and the fourth sub-function surface, the third sub-active material layer is arranged on the third sub-function surface, and the fourth sub-active material layer is arranged on the fourth sub-function surface;

The third sub-active material layer is provided with a second groove, 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.

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 configuration of the present application and its other inventive objects and beneficial effects will be more clearly understood by the description of the preferred embodiments in conjunction with the accompanying drawings.

Description of drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings 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. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

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

Fig. 2 is the sectional view along B-B among Fig. 1;

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

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

Fig. 5 is the sectional view along A-A in Fig. 4;

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

7 is a top view of a 3D microscope of a second protrusion provided by an embodiment of the present application;

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

FIG. 9 is a schematic structural diagram of a matrix arrangement of solder prints according to an embodiment of the present application;

FIG. 10 is a schematic structural diagram of another kind of solder prints arranged in a matrix according to an embodiment of the application;

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

Description of reference numbers:

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 - the second groove;

20-pole ear;

21 - the first polar ear;

22 - the second pole;

30-welding area;

31-welding;

311 - helix;

312a - the first protrusion;

312b - the second protrusion;

40 - protective layer;

41 - the first protective layer;

42-Second protective layer.

Detailed ways

The pole piece may include a pole piece body and a pole ear, 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. The pole piece body is provided with an empty foil area, 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, when the current collector is connected to the tab, only one of the surfaces of the current collector can be used. By arranging empty foil areas to connect the tabs, it is necessary to remove the active material layers on the two opposite surfaces of the current collector, resulting in a large number of active material layers removed, which affects the energy density of the battery.

In response to the above technical problems, the embodiments of the present application provide a pole piece and a battery, the pole piece includes a pole piece body and a pole lug, and the pole lug is used to electrically connect the pole piece body with an external circuit. The current collector includes two oppositely arranged functional surfaces, and the 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 tabs are welded with 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, and the active material layer on the backside of the groove is retained. The total amount of active material layers removed can be reduced, thereby increasing 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 described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments It is a part of the embodiments of the present application, but not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

As shown in FIG. 1 to FIG. 2 , an embodiment of the present application provides a pole piece 100 , and the pole piece 100 can be used in a battery. The pole piece 100 includes a pole piece body 10 and a pole tab 20 , and the pole piece 20 is used to electrically connect 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 solder print 31 .

When there are multiple solder prints 31 , the plurality of solder prints 31 together form the bonding area 30 . Among them, a plurality of solder prints 31 are arranged in the welding area 30 at intervals, and a single solder print 31 is small, so that the input energy required to form each solder print 31 is small, and it is avoided that the pole piece body 10 is overheated due to excessive heat. The phenomenon of welding or welding through ensures the performance of the pole piece 100 .

At least part of the solder print 31 is located on the side of the tab 20 facing away from the pole piece body 10 and protrudes toward the side facing away from the pole piece body 10 . In this way, when welding the tab 20 and the pole piece body 10 , the welding can be performed from the side of the tab 20 away from the pole piece body 10 , rather than from the side of the pole piece body 10 away from the pole piece 20 . 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 solder print 31 located on the side of the tab 20 away from the pole piece body 10 may be spiral. One turn is one spiral 311 . There is a distance between the adjacent two turns of the helical wires 311 , and the distance is favorable for heat dissipation during the welding process, and avoids over-welding or welding-through caused by heat accumulation.

The number of turns of the spiral of the helical solder print 31 is 1 turn to 10 turns. The number of turns of the helix of the solder print 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 solder print 31 is greater than 10, the solder print 31 is too large, and the energy input to form the solder print 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 print 31, the distance between any two adjacent spirals 311 is L1, and the distance L1 between any two adjacent spirals 311 is in the range 0.01mm-3mm. For example, the distance L1 between any two adjacent turns of the helical wires 311 may be 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, or 3 mm, 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, resulting in poor heat dissipation during the welding process. When the distance L1 between any two adjacent turns of the helix 311 is greater than 3 mm, the distance between any two adjacent 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 large. Small, the welding strength is low.

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

As shown in FIG. 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 electrode piece or a positive electrode piece. Sure. For example, when the current collector 11 is an aluminum foil and the material of the active material layer 12 is a ternary material or a positive electrode active material such as lithium iron phosphate, the pole piece 100 is a positive electrode piece; when the current collector 11 is a copper foil and the material of the active material layer 12 When it is a negative electrode active material such as graphite and silicon, the pole piece 100 is a negative electrode piece.

Wherein, the current collector 11 includes two oppositely arranged functional surfaces, and the active material layers 12 are respectively arranged on the two functional surfaces. The functional surfaces of the current collector 11 refer to the largest and opposite two 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 only on one functional surface of the current collector 11 , or may be coated on both functional surfaces of the current collector 11 at the same time.

As shown in FIG. 2 and FIG. 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 connecting with the tabs. 20 Electrical connections. 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 tabs 20, and the active material layer 12 on the side of the current collector 11 facing 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 the edge in the width direction of the pole piece body 10 , and the 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 provided 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 both be provided with the active material layer 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 pole piece The width direction of the sheet body 10 and the current collector 11 . The width direction and the length direction in the embodiments of the present application are only for the convenience of description, and do not mean any size limitation. For example, the width may be greater than, less than, or equal to the length.

Specifically, in one pole piece 100, the two functional surfaces of the current collector 11 may be the first functional surface and the second functional surface, respectively, the active material layer may be the first active material layer and the second active material layer, 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. The first active material layer is provided with a groove 121, and the bottom wall of the groove 121 is the 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.

The grooves 121 can 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 foam cleaning, and the present 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 may be covered with a protective layer 40 , the protective layer 40 can fix the tab 20 , and the protective layer 40 can avoid the groove 121 and the The burr on the ear 20 pierces the membrane in the cell adjacent to the groove 121 . Wherein, the protective 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 0.01 mm, 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 relatively thick, resulting in a relatively large 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 1 mm, the groove 121 is small, and the exposed functional surface area of the current collector 11 is small, resulting in a relatively strong connection between the tab 20 and the current collector 11. Low. When the length of the groove 121 is greater than 40 mm, the groove 121 is larger, and the active material layer 12 is removed more, which has a greater 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 details are not repeated here.

In some embodiments, the tabs 20 and the pole piece body 10 may be connected by ultrasonic welding. In ultrasonic welding, the welding head for ultrasonic welding needs to contact the side of the current collector 11 away from the tab 20 , and perform pressure 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 lower energy density of the pole piece 100 . In addition, during the welding process, the welding head of ultrasonic welding will wear out and need to be replaced regularly, which increases the workload of the staff. The wear of the welding head easily leads 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. In addition, ultrasonic welding will form relatively sharp needle-shaped welding protrusions. If the pole piece 100 is assembled into a battery, it is easy to pierce the diaphragm adjacent to the needle-shaped welding protrusion, so that a short circuit occurs between the positive electrode and the negative electrode. cause safety incidents.

In this embodiment, the tabs 20 and the current collector 11 may be connected by laser welding. Laser welding does not need to use a welding head, which can effectively avoid the above problems of ultrasonic welding. In the laser welding process, the laser welding is to irradiate a laser 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 between the tab 20 and the current collector 11 , and the plurality of welding marks 31 together form the welding area 30 .

By irradiating laser welding from the side of the tab 20 away from the current collector 11 , it is not necessary to clean 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 high.

As shown in FIGS. 4 and 5 , the solder prints 31 on the side of the tab 20 facing away from the current collector 11 protrude toward the side facing away from the current collector 11 , thereby forming a first protrusion 312 a. The shape of the first protrusion 312a may be a spiral shape. On the side of the tab 20 facing away from the current collector 11 , each spiral 311 of the solder print 31 together forms a first protrusion 312a. There is a plane structure between two adjacent helixes 311, and the plane structure is that the surface of the tab 20 is not formed with the helix 311, and the tab 20 between the two adjacent helixes 311 is conducive to the process of forming the solder print 31. of heat dissipation.

In some examples, along the thickness direction of the pole piece body 10 , the solder print 31 penetrates 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 less than the sum of the thicknesses of the tab 20 and the current collector 11 . At this time, the solder print 31 is formed on the side of the tab 20 away from the current collector 11 , while the surface of the current collector 11 on the side away from the tab 20 is not formed with the solder print 31 , and the surface of the current collector 11 on the side away from the tab 20 is not formed. for the plane. In this way, the solder print 31 has less influence on the active material layer 12 on the side of the current collector 11 away from the tab 20 .

In other examples, as shown in FIG. 6 to FIG. 8 , along the thickness direction of the pole piece body 10 , the solder print 31 penetrates the tab 20 and the current collector 11 . Since there is heat accumulation in the welding process, the laser penetration will gradually increase as the welding progresses. After reaching a certain level, the penetration exceeds the sum of the thicknesses of the tab 20 and the current collector 11, so that the current collector 11 is away from the tab 20 when the current collector 11 is away from the tab 20. Solder pads 31 are also formed on one side. At this time, the solder print 31 can be observed on both the surface of the tab 20 facing away from the current collector 11 and the surface of the current collector 11 facing away from the tab 20 . Wherein, the solder print 31 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 influence of the solder print 31 on the diaphragm on the side. The solder print 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 projection 312b.

In some other examples, in the same solder print 31 , part of the solder print 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 part of the area. For example, the solder seal 31 includes an outer edge portion and a middle portion, and the outer edge portion is annularly provided outside the middle portion. Along the thickness direction of the pole piece body, the outer edge penetrates through the tab 20 and the current collector 11 , and the outer edge on the side of the current collector 11 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 pressing effect is not good, resulting in a gradual decrease in the defocusing amount of 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 print 31 can be observed on the surface of the current collector 11 on the side facing away from the tab 20 . The outer edge of the current collector 11 on the side facing away from the tab 20 protrudes toward the side facing away from the tab 20, thereby forming the second protrusion 312b. Among them, the outer edge portion 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 influence of the outer edge portion on the diaphragm on the side.

In addition, along the thickness direction of the pole piece body 10 , the middle portion penetrates through the tab 20 , and the middle portion is located in a partial region of the current collector 11 close to the tab 20 in the thickness direction. At this time, the middle portion of the solder print 31 cannot be seen 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 edge portions 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 on the side away from the tab 20 overlaps with the outer edge of the tab 20 on the side away from the pole piece body 10 .

Alternatively, part of the outer edge portion may penetrate 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 solder print 31 forms the first protrusion 312a on the side of the tab 20 facing 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 side 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 large, and the welding reliability is relatively high.

Wherein, the first protrusions 312 a and the second protrusions 312 b may be disposed opposite to each other along the thickness direction of the current collector 11 . The projection of the second protrusion 312 b on the current collector 11 is located within the projection of the first protrusion 312 a on the current collector 11 . As shown in FIG. 7 and FIG. 8 , the second protrusion 312b may be disposed opposite to the outer helix of the first protrusion 312a (equivalent to an implementation of the outer edge). The outer helix can be the outermost helix, or the outer helix can also be any one of the helixes 311 located in the outermost helix and the innermost helix, 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 circular ring; or, as shown in FIG. 8, the shape of the second protrusion 312b is close to a circular ring, and there are multiple There is no raised break point, and at the break point, the solder print 31 does not penetrate the current collector 11 and is flat, that is, the break point is the planar structure of the current collector 11 . In other examples, the second protrusions 312b may also be formed at other positions of the solder print 31. For example, the second protrusions 312b may also be spiral, which is not limited in this application.

In some embodiments, the protrusion height of the second protrusion 312b is less than or equal to the protrusion 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 facing away from the tab 20 .

As shown in FIG. 5 , on the side of the tab 20 away from the current collector 11 , in any spiral 311 of the solder print 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 312a to the height H of the first protrusion 312a is greater than or equal to 1. 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 protrusions 312a to the height H of the first protrusions 312a is less than 1, the shape of the first protrusions 312a is relatively sharp, so that the first protrusions 312a are easily pierced in the battery. The adjacent separator will affect the safety of the battery.

On the side of the tab 20 facing away from the current collector 11 , in any spiral 311 of the solder print 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 and the pole piece body 10 at the first protrusion 312a is small, and the welding strength is low. When the width W of the first protrusions is greater than 0.2 mm, the energy input when forming the first protrusions 312 a is relatively high, which affects the active material layer 12 near the solder print 31 .

On the side of the tab 20 facing away from the current collector 11, in any circle of the spiral 311 of the solder print 31, the height H of the first protrusion 312a is less than or equal to 0.1 mm. For example, the protrusion height H of the first protrusion 312a 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 protrusion height H of the first protrusion 312a is greater than 0.1 mm, the first protrusion 312a is relatively high, and the first protrusion 312a is likely to pierce the adjacent separator in the battery, resulting in a short circuit between the positive and negative electrodes of the battery .

On the side of the current collector 11 away from the tab 20, the size parameters of the second protrusions 312b can be set with reference to the range of the size parameters of the first protrusions 312a. For example, in any turn 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 of the range is 0.01mm-0.2mm.

As shown in FIG. 9 and FIG. 10 , a plurality of solder prints 31 are provided on the welding area 30 , and the distance between the outermost spirals 311 of any two adjacent spiral solder prints 31 (L2 in FIG. 9 ) ) may be less than or equal to 5mm. This distance is the distance between the two solder prints 31 . For example, the distance L2 between two adjacent solder prints 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 prints 31 is greater than 5 mm, the middle solder prints 31 in the welding area 30 are relatively scattered, the number of solder prints 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 may be arranged in a matrix. The plurality of solder prints 31 may be arranged in a matrix with multiple rows and multiple columns. The number of rows in the matrix may 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 may 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 altogether 40 spiral solder prints 31 in the matrix. The matrix arrangement is more beautiful and tidy, and the distribution of the solder prints 31 is relatively even, so that the welding uniformity of the welding area 30 is better.

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

Wherein, the number of solder prints 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, 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 are arranged in 3 rows*4 columns. The total is 36.

Exemplarily, when forming the matrix solder prints 31 as shown in FIG. 9 , the tabs 20 are first placed in the grooves 121 , and the tabs 20 are pressed with a clamp; then laser welding is performed to form a plurality of spiral solder prints 31 . . The distance between the spiral center of the solder print 31 and the outer edge of the outermost spiral line 311 of the solder print 31 is 0.25mm, the interval between two adjacent solder prints 31 is 0.5mm, and the first protrusion 312a The width W (in one spiral 311) is 0.05 mm, and the number of spirals 311 is four. The laser is continuously welded on the surface of the tab 20, and the welding time to form a single welding mark 31 is 0.05s, forming 10*4 welding marks 31 in total, and the area of the welding area 30 is 3.5mm*9.5mm.

In addition, this embodiment also provides a battery, the battery may include at least two pole pieces 100 stacked on each other with opposite polarities, and a separator 200 is disposed between each adjacent two pole pieces 100, and the separator 200 is used to prevent The pole pieces 100 with opposite polarities come into contact, resulting in a short circuit of the battery. 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, and the first pole piece 110 can be a positive pole piece or a negative pole piece. The diode sheet 120 may be a negative electrode or a positive electrode.

In some embodiments, the first pole piece 110 includes a first tab 21, a first current collector, and 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 arranged oppositely. 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 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 in the second within the projection of the sub-active material layer on the first current collector. The portion of the second sub-active material layer facing the first groove 1211 is in contact with the diaphragm 200 . In this way, when forming the first groove 1211, 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 improve 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 burrs on the first tab 21 (formed by the solder print 31) can be prevented from piercing the diaphragm 200, thereby improving the safety of the battery sex. The first protective layer 41 may be disposed on the surface of the diaphragm 200 facing the first groove 1211 , or the first protective layer 41 may be disposed on the surface of the first tab 21 facing the diaphragm 200 .

In 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 the burr, the burr directly contacts the second pole piece 120 to cause a short circuit of the battery, so as to prevent the battery from being short-circuited. 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 surface of the second pole piece 120 facing the side of the diaphragm 200 .

In some other examples, between the diaphragm 200 adjacent to the first groove 1211 and the first pole 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 provided 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 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 grooves 1211 , which can prevent the first grooves 1211 and the burrs formed on the first tabs 21 from piercing the diaphragm 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, 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 second The functional surface of the current collector includes a third sub-functional surface and a fourth sub-functional surface arranged oppositely. 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. The third sub-active material layer is provided with a second groove, 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. The portion of the fourth sub-active material layer facing the second groove 1212 is in contact with the adjacent diaphragm 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 improve the energy density of the battery.

In some examples, a second protective layer 42 is disposed between the diaphragm 200 adjacent to the second groove 1212 and the second tab 22 . In 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 the second pole tab 22 ; and the diaphragm 200 adjacent to the second groove 1212 and the first pole adjacent to the diaphragm 200 The second protective layer 42 is disposed between the sheets 110 . In this way, the safety of the battery can be improved, and the principle thereof 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 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 second groove 1212 and the burrs formed on 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 may form a cell in the battery. The battery cell refers to the electrochemical cell containing positive and negative electrode pieces installed inside the battery. The battery cell is generally not used directly. 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 cells can be wound cells or laminated cells.

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 beginning of the winding to finally form a wound cell.

In other examples, the laminated cell includes a plurality of first pole pieces 110 and a plurality of second pole pieces 120. During the processing, the first pole pieces 110 and the second pole pieces 120 are alternately stacked in the same direction. A diaphragm 200 is arranged between two adjacent first pole pieces 110 and the second pole piece 120 , and is finally stacked to form a laminated 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 errors in a certain range due to the influence of the manufacturing process, and those skilled in the art may consider these errors to be ignored.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present application. scope.

Claims (14)

1. A pole piece, comprising: the pole piece body comprises a current collector, a first active substance layer and a second active substance layer, the current collector comprises a first functional surface and a second functional surface which are oppositely arranged, the first active substance layer is arranged on the first functional surface, and the second active substance layer is arranged 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;

utmost point ear with in the recess the mass flow body welding forms the seal of welding, at least part the seal of welding is located the utmost point ear deviate from on the face of mass flow body one side, and the orientation deviates from the protruding first arch that forms in one side of the mass flow body.

2. The pole piece of claim 1, wherein a projection of the recess on the current collector is within a projection of the second active material layer on the current collector.

3. The pole piece of claim 1, wherein the weld penetrates the tab and the current collector in a thickness direction of the pole piece body; the welding seal on one side of the current collector, which is far away from the lug, protrudes towards one side, which is far away from the lug, to form a second protrusion, and the second active material layer covers the second protrusion; or,

the welding seal comprises an outer edge part and an intermediate part, and the outer edge part is arranged on the outer side of the intermediate part in a surrounding mode; follow the thickness direction of pole piece body, the outer fringe portion runs through utmost point ear with the mass flow body is located the mass flow body deviates from utmost point ear one side the outer fringe portion orientation deviates from one side arch of utmost point ear forms the second arch, second active substance layer covers the second is protruding.

4. The pole piece of claim 1 wherein the weld comprises an outer rim portion and an intermediate portion, the outer rim portion being disposed around the outside of the intermediate portion;

along the thickness direction of pole piece body, the intermediate part runs through utmost point ear, just the intermediate part is located be close to on the thickness direction of mass flow body in the subregion of utmost point ear.

5. The pole piece of claim 1, wherein the weld penetrates the tab in a thickness direction of the pole piece body, and the weld is located in a partial region close to the tab in the thickness direction of the current collector.

6. The pole piece of claim 4, wherein along the thickness direction of the pole piece body, the current collector is away from the outer edge portion of one side of the tab and is overlapped with the outer edge portion of one side of the tab away from the pole piece body.

7. The pole piece of claim 3 wherein the height of the second protrusion is less than or equal to the height of the first protrusion.

8. The pole piece of any one of claims 1 to 7, wherein the plurality of welding imprints are arranged at intervals and form a welding area, and the welding imprints on the side of the tab facing away from the pole piece body are spiral in shape;

on a side of the tab facing away from the current collector:

the number of turns of the welded spiral line is 1 to 10;

and/or the distance between any two adjacent welding marks is less than or equal to 5 mm;

and/or, in each said weld impression, the distance between the centre of the spiral of said weld impression to the outer edge of the outermost turn of the spiral of said weld impression ranges from 0.05mm to 2.5 mm;

and/or in any circle of spiral line of the welding seal, the ratio of the width of the spiral line to the height of the projection of the spiral line is more than 1;

and/or, in any circle of spiral line of the welding seal, the width range of the spiral line is 0.01mm-0.2 mm;

and/or the height of the first bulge is less than or equal to 0.1 mm;

and/or the distance between any two adjacent circles of spiral lines in each welding mark ranges from 0.01mm to 3 mm.

9. The pole piece of any one of claims 1 to 7, wherein the groove has a groove depth in the range of 0.01mm to 0.2 mm;

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

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

10. A battery is characterized by comprising at least two pole pieces which are mutually overlapped and have opposite polarities, a diaphragm is arranged between every two adjacent pole pieces,

at least one of the pole pieces is a pole piece according to any one of claims 1 to 9.

11. The battery of claim 10, wherein at least two of the pole pieces comprise first and second pole pieces of opposite polarity;

the first pole piece comprises a first pole lug, a first current collector, a first sub active material layer and a second sub active material layer, the first current collector comprises a first sub function surface and a second sub function surface which are oppositely arranged, the first sub active material layer is arranged on the first sub function surface, and the second sub active material layer is arranged on the second sub function 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 function surface; the first tab is electrically connected with the first sub-function surface in the first groove;

the projection of the first groove on the first current collector is positioned in the projection of the second sub-active material layer on the first current collector.

12. The battery of claim 11, wherein a first protective layer is disposed between the separator adjacent the first groove and the first tab; and/or a first protective layer is arranged between the diaphragm adjacent to the first groove and the second pole piece adjacent to the diaphragm;

the projection of the first groove on the first current collector is positioned in the projection of the first protective layer on the first current collector.

13. The battery of claim 11 or 12, wherein the second tab comprises a second tab, a second current collector, a third sub-active material layer and a fourth sub-active material layer, the second current collector comprises a third sub-functional surface and a fourth sub-functional surface that are oppositely disposed, 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;

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 second tab is electrically connected with the third sub-function surface in the second groove;

and the projection of the second groove on the second current collector is positioned in the projection of the fourth sub-active material layer on the second current collector.

14. The battery of claim 13, wherein a second protective layer is disposed between the separator adjacent the second groove and the second tab; and/or a second protective layer is arranged between the diaphragm adjacent to the second groove and the first pole piece adjacent to the diaphragm;

and the projection of the second groove on the second current collector is positioned in the projection of the second protective layer on the second current collector.

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