CN216288521U

CN216288521U - Pole piece and battery

Info

Publication number: CN216288521U
Application number: CN202122853602.XU
Authority: CN
Inventors: 彭宁
Original assignee: Zhuhai Cosmx Battery Co Ltd
Current assignee: Zhuhai Cosmx Battery Co Ltd
Priority date: 2021-11-18
Filing date: 2021-11-18
Publication date: 2022-04-12
Anticipated expiration: 2031-11-18

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

Background

The lithium ion battery has the advantages of large capacity, small volume, light weight, environmental protection and the like, and is widely applied to industries such as digital electronic products, electric automobiles and the like.

In the related art, the 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. Be equipped with empty paper tinsel district on the pole piece body, the active material layer in the empty paper tinsel district is got rid of to expose two relative surfaces of the mass flow body in the empty paper tinsel district, utmost point ear welds on the mass flow body in the empty paper tinsel district.

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

SUMMERY OF THE UTILITY MODEL

In view of the above problems, 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 object, the embodiments of the present application provide the following technical solutions:

a first aspect of an embodiment of the present application provides a pole piece, including: 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 bottom wall of the groove is a first functional surface;

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 deviates from the protruding first arch that forms in one side of current collector.

The pole piece that this application embodiment provided, pole piece include pole piece body and utmost point ear, and utmost point ear is used for carrying out electric connection with pole piece body and outside circuit. The current collector includes two functional surfaces disposed opposite to each other, and the active material layers are respectively disposed on the two functional surfaces. Be provided with the recess on one of them side of pole piece body, the groove diapire wall of recess is the functional surface of mass flow body, and the recess is used for setting up utmost point ear. The tab is positioned in the groove and 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 for connecting the tabs, and the active material layer on the side of the current collector facing away from the grooves is retained. The total amount of the removed active material layer can be reduced, thereby improving the energy density of the battery.

In one possible implementation, 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 one possible implementation mode, the welding print penetrates through the lug and the current collector along the thickness direction of the pole piece body; the welding seal positioned 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; alternatively, the first and second electrodes may be,

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 manner; along the thickness direction of pole piece body, utmost point ear and current collector are run through to the outer fringe portion, and the outer fringe portion orientation that is located current collector and deviates from utmost point ear one side is deviated from one side arch formation second arch of utmost point ear, and it is protruding that second active material layer covers the second.

In one possible implementation, the weld includes an outer rim portion and an intermediate portion, the outer rim portion being disposed circumferentially outside the intermediate portion;

the middle part of the pole piece body penetrates through the pole lug along the thickness direction of the pole piece body, and the middle part is positioned in a partial area close to the pole lug in the thickness direction of the current collector.

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

In a possible implementation manner, along the thickness direction of the pole piece body, the current collector deviates from the outer edge part on one side of the pole lug and is overlapped with the outer edge part on one side of the pole piece body of the pole lug.

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

In one possible implementation mode, the welding imprints are distributed at intervals and form a welding area, and the welding imprints on the side, away from the pole piece body, of the pole lug are spiral in shape;

on the 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 weld impression, the distance between the center of the spiral of the weld impression to the outer edge of the outermost turn of the spiral of the weld impression ranges from 0.05mm to 2.5 mm;

and/or in any circle of spiral line of the welding mark, 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 welding and printing, 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.

In one possible implementation, the groove depth of the groove ranges from 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 of the groove along the length direction of the pole piece body ranges from 1mm to 30 mm.

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

at least one of the pole pieces is the pole piece of the first aspect described above.

The battery that this application embodiment provided, battery include the pole piece, and the pole piece includes pole piece body and utmost point ear, and utmost point ear is used for carrying out electric connection with pole piece body and outside circuit. The current collector includes two functional surfaces disposed opposite to each other, and the active material layers are respectively disposed on the two functional surfaces. Be provided with the recess on one of them side of pole piece body, the groove diapire wall of recess is the functional surface of mass flow body, and the recess is used for setting up utmost point ear. The tab is positioned in the groove and 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 for connecting the tabs, and the active material layer on the side of the current collector facing away from the grooves is retained. The total amount of the removed active material layer can be reduced, thereby improving the energy density of the battery.

In one 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 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 a 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.

In one possible implementation manner, a first protective layer is arranged between the diaphragm adjacent to the first groove and the first lug; 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.

In one possible implementation manner, the second electrode sheet includes a second electrode tab, a second current collector, a third sub-active material layer and a fourth sub-active material layer, the second current collector includes a third sub-functional surface and a fourth sub-functional surface which 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 a 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.

In one possible implementation, a second protective layer is arranged between the diaphragm adjacent to the second groove and the second pole lug; 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;

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.

The construction and other objects and advantages of the present application will be more apparent from the description of the preferred embodiments taken in conjunction with the accompanying drawings.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a top view of a pole piece according to an embodiment of the present disclosure;

FIG. 2 is a cross-sectional view taken along line B-B of FIG. 1;

FIG. 3 is a top view of a weld zone provided in embodiments of the present application;

FIG. 4 is an enlarged schematic view of a spiral solder mark provided in an embodiment of the present application;

FIG. 5 is a sectional view taken along line A-A of FIG. 4;

fig. 6 is a top view of a 3D microscope of a weld mark on a side of a current collector facing away from a tab according to an embodiment of the present disclosure;

FIG. 7 is a top view of a second bump in a 3D microscope according to an embodiment of the present disclosure;

FIG. 8 is a top view of another 3D microscope with second protrusions provided in embodiments of the present application;

FIG. 9 is a schematic structural diagram of a solder print arranged in a matrix according to an embodiment of the present disclosure;

FIG. 10 is a schematic structural diagram of another solder print in a matrix arrangement according to an embodiment of the present application;

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

Description of reference numerals:

100-pole piece;

110-a first pole piece;

120-a second pole piece;

200-a membrane;

10-a pole piece body;

11-a current collector;

12-an active material layer;

121-grooves;

1211 — a first groove;

1212 — a second groove;

20-pole ear;

21-a first tab;

22-a second tab;

30-a weld zone;

31-welding and printing;

311-helix;

312 a-a first projection;

312 b-a second projection;

40-a protective layer;

41-a first protective layer;

42-second protective layer.

Detailed Description

The pole piece can include pole piece body and utmost point ear, and the pole piece body includes the current collector and active substance layer, and active substance layer sets up on two relative surfaces of current collector. Be equipped with empty paper tinsel district on the pole piece body, the active material layer in the empty paper tinsel district is got rid of to expose two relative surfaces of the mass flow body in the empty paper tinsel district, utmost point ear welds on the mass flow body in the empty paper tinsel district.

However, when the current collector is coupled to the tab, only one of the surfaces of the current collector may be used. Connect utmost point ear through setting up empty foil district, need all get rid of the active substance layer on two relative surfaces of mass flow body, the active substance layer that leads to getting rid of is more, causes the influence to the energy density of battery.

To solve the technical problem, the embodiment of the application provides a pole piece and a battery, wherein the pole piece comprises a pole piece body and a pole lug, and the pole lug is used for electrically connecting the pole piece body with an external circuit. The current collector includes two functional surfaces disposed opposite to each other, and the active material layers are respectively disposed 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; and the lug is welded with the current collector in the groove. In this way, only a portion of the active material layer on one of the functional surfaces of the current collector is removed to attach the tabs, and the active material layer on the back of the grooves is retained. The total amount of the removed active material layer can be reduced, thereby improving the energy density of the battery.

In order to make the objects, 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 with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

As shown in fig. 1-2, embodiments of the present application provide a pole piece 100, where the pole piece 100 may be used in a battery. The pole piece 100 includes a pole piece body 10 and a tab 20, and the tab 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 and form a weld 31.

When the solder stamp 31 is plural, the plural solder stamps 31 collectively form the land 30. The plurality of welding imprints 31 are arranged in the welding area 30 at intervals, and the single welding imprint 31 is small, so that the input energy required for forming each welding imprint 31 is small, the phenomenon that the pole piece body 10 is over-welded or welded through due to excessive heat is avoided, and the performance of the pole piece 100 is ensured.

At least part of the welding seal 31 is located on the surface of the tab 20 on the side away from the pole piece body 10, and is protruded toward the side away from the pole piece body 10. Like this, when welding utmost point ear 20 and pole piece body 10, can follow utmost point ear 20 and deviate from pole piece body 10 one side and weld, but not deviate from utmost point ear 20 one side from pole piece body 10 and weld, can reduce the influence that deviates from utmost point ear 20 one side active material layer 12 to utmost point ear body 10.

As shown in fig. 4, the shape of the welding mark 31 on the side of the tab 20 facing away from the pole piece body 10 may be a spiral shape, the spiral-shaped welding mark 31 includes a plurality of spiral lines 311, and one of the spiral-shaped welding marks 31 is one spiral line 311. The distance is reserved between every two adjacent circles of spiral lines 311, heat dissipation in the welding process is facilitated through the distance, and overbonding or welding penetration caused by heat accumulation is avoided.

The number of turns of the spiral line of the spiral-shaped solder mark 31 is 1 to 10. The number of turns of the spiral line of the solder mark 31 may be set to 1 turn, 2 turns, 3 turns, 4 turns, 5 turns, 8 turns, 10 turns, or the like according to practical situations, which is not limited in this application. When the number of turns of spiral-shaped solder mark 31 is greater than 10 turns, the energy input to form solder mark 31 is high due to the excessively large solder mark 31, which affects active material layer 12 at solder region 30.

As shown in fig. 4, in each spiral-shaped solder mark 31, the distance between any two adjacent turns of the spiral line 311 is L1, and the distance L1 between any two adjacent turns of the spiral line 311 ranges from 0.01mm to 3 mm. For example, the distance L1 between any two adjacent turns of the spiral line 311 may be 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, or 3mm, which is not limited in this embodiment. When the distance L1 between any two adjacent turns of spiral lines 311 is less than 0.01, the distance between any two adjacent turns of spiral lines 311 is too close, and the heat dissipation is poor in the welding process. When the distance L1 between any two adjacent circles of spiral lines 311 is greater than 3mm, the distance between any two adjacent circles of spiral lines 311 is too large, the effective welding area between the tab 20 and the pole piece body 10 is small, and the welding strength is low.

In each spiral shaped solder stamp 31, the distance between the center of the spiral of the solder stamp 31 to the outer edge of the outermost turn 311 of the solder stamp 31 may range from 0.05mm to 2.5 mm. I.e. the distance from the center of the solder stamp 31 to the outer edge of the solder stamp 31. For example, the distance from the spiral center of the solder mark 31 to the outer edge of the outermost spiral line 311 of the solder mark 31 may be 0.05mm, 0.25mm, 0.5mm, 1mm, 1.5mm, or 2.5mm, etc., which is not limited by the embodiment. When the distance from the spiral center of the welding mark 31 to the outer edge of the outermost spiral line 311 of the welding mark 31 is less than 0.05mm, the welding mark 31 is too small, the contact area between the tab 20 at the welding mark 31 and the pole piece body 10 is too small, effective welding tension cannot be formed, and the welding strength is low. When the distance from the spiral center of the solder mark 31 to the outer edge of the outermost spiral line 311 of the solder mark 31 is greater than 2.5mm, the solder mark 31 is too large, and the energy input to form the solder mark 31 is high, affecting the active material layer 12 at the solder region 30.

As shown in fig. 2, the electrode sheet body 10 includes a current collector 11 and an active material layer 12, and the electrode sheet 100 may be a negative electrode sheet or a positive electrode sheet, which may be determined according to specific selection of materials of the current collector 11 and each active material layer 12. 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 active material such as lithium iron phosphate, the electrode sheet 100 is a positive electrode sheet; when the current collector 11 is a copper foil and the material of the active material layer 12 is a negative active material such as graphite, silicon-based, etc., the electrode sheet 100 is a negative electrode sheet.

Here, current collector 11 includes two functional surfaces disposed oppositely, and active material layers 12 are respectively disposed on the two functional surfaces. The functional surfaces of current collector 11 refer to the largest and opposite two surfaces of current collector 11 for coating active material layer 12. Active material layer 12 in electrode sheet 100 of the present application may be coated on only one functional surface of current collector 11, or simultaneously coated on both functional surfaces of current collector 11.

As shown in fig. 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 a portion of the functional surface, which is used for electrical connection with the tab 20. In this way, only active material layer 12 on one of the functional surfaces of current collector 11 is removed to attach tab 20, and active material layer 12 on the side of current collector 11 facing away from recess 121 and facing recess 121 is retained. The total amount of active material layer 12 removed can be reduced, thereby improving the energy density of the battery.

As shown in fig. 3, the groove 121 may be close to the edge of the pole piece body 10 in the width direction, and one side of the groove 121 close to the edge is open. That is, the outer side of groove 121 near the edge is not provided with active material layer 12, and the outer side of groove 121 far from the edge is provided with active material layer 12. The length of the groove 121 is smaller than the length of the current collector 11 along the width direction of the pole piece body 10. In addition, the active material layer 12 may be provided on both outer sides of both ends of the groove 121 in the longitudinal direction of the pole piece body 10.

Note that the X direction in fig. 1, that is, the longitudinal direction of the pole piece 100, is also the longitudinal direction of the pole piece body 10 and the current collector 11; the Y direction in fig. 1, i.e., the width direction of the pole piece 100, is also the width direction of the pole piece body 10 and the current collector 11. The width direction and the length direction in the embodiments of the present application are for convenience of description only and are not meant to limit any size. For example, the width may be greater than, less than, or equal to the length.

Specifically, in one electrode sheet 100, two functional surfaces of the current collector 11 may be a first functional surface and a second functional surface, respectively, and the active material layer may be a first active material layer and a second active material layer, respectively, where 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 121, and the groove bottom wall of the groove 121 is a first functional surface. While the second active material layer facing the groove 121 is not removed and remains, at this time, the projection of the groove 121 on the current collector 11 is located in the projection of the second active material layer on the current collector 11. Therefore, the total amount of the second active material layer removed can be reduced, thereby improving the energy density of the battery.

Here, the recess 121 may be formed by removing a corresponding portion of the active material layer 12 by washing to expose the current collector 11. The cleaning mode can be laser cleaning, mechanical cleaning or foaming glue cleaning and the like, and the cleaning mode is not limited in the application.

In some embodiments, as shown in fig. 2, the side of the tab 20 facing away from the current collector 11 may be covered with a protective layer 40, the protective layer 40 has a fixing effect on the tab 20, and the protective layer 40 can prevent the groove 121 and burrs on the tab 20 from piercing through the membrane in the battery adjacent to the groove 121. Wherein the protective layer 40 completely covers the recess 121.

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

The length of the groove 121 along the width direction of the pole piece body 10 ranges from 1mm to 40 mm. For example, the length may be 1mm, 2mm, 5mm, 10mm, 15mm, 20mm, 30mm, or 40mm, and the like, which is not limited in the embodiments of the present application. Along the width of pole piece body 10, when the length of recess 121 is less than 1mm, recess 121 is less, and the functional surface area that current collector 11 exposes is less, results in the joint strength between utmost point ear 20 and the current collector 11 to be lower. When the length of groove 121 is greater than 40mm, groove 121 is larger, active material layer 12 is removed more, and a large influence is exerted 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 1mm to 30 mm. For example, the length may be 1mm, 2mm, 5mm, 10mm, 15mm, 20mm, 25mm, or 30mm, and the like, which is not limited in the embodiments 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 is not described again.

In some embodiments, the tab 20 and the pole piece body 10 may be joined by ultrasonic welding. In the ultrasonic welding, it is necessary to bring a welding head for ultrasonic welding into contact with the side of current collector 11 away from tab 20, and perform pressure vibration to weld tab 20 and current collector 11 together. At this time, it is necessary to clean the active material layers 12 on both 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, in the welding process, the welding head for ultrasonic welding is worn and needs to be replaced periodically, so that the workload of workers is increased. The wear of the welding head easily causes the problem of insufficient welding or over welding between the tab 20 and the current collector 11, thereby affecting the performance of the battery. Moreover, ultrasonic welding may form a relatively sharp needle-shaped welding protrusion, and if the pole piece 100 is assembled into a battery, the separator adjacent to the needle-shaped welding protrusion is easily pierced, so that a short circuit phenomenon occurs between the positive pole piece and the negative pole piece, and a safety accident may be caused.

In this embodiment, the tab 20 and the current collector 11 may be connected by laser welding. The welding head is not needed in the laser welding, and the problems of ultrasonic welding can be effectively avoided. In the laser welding process, laser is irradiated on the tab 20 from the side of the tab 20 away from the current collector 11, so as to weld the tab 20 and the current collector 11. After the laser welding is completed, a plurality of spaced welding imprints 31 are formed at the welding positions of the tab 20 and the current collector 11, and the welding zones 30 are formed by the plurality of welding imprints 31.

Laser welding is irradiated from one side of the tab 20, which is far away from the current collector 11, so that the active material layer 12 on the side of the current collector 11, which is far away from the tab 20, does not need to be cleaned, and the energy density of the pole piece 100 is high.

As shown in fig. 4 and 5, the weld 31 on the side of the tab 20 facing away from the current collector 11 protrudes toward the side facing away from the current collector 11, thereby forming a first protrusion 312 a. The first protrusion 312a may be spiral in shape. On the side of the tab 20 facing away from the current collector 11, the individual spiral lines 311 of the weld impressions 31 jointly form a first projection 312 a. Be planar structure between two adjacent helices 311, planar structure is that utmost point ear 20 does not form the surface of helix 311, and utmost point ear 20 between two adjacent helices 311 is favorable to the heat dissipation of weld mark 31 formation in-process.

In some examples, the weld mark 31 penetrates through the tab 20 in the thickness direction of the pole piece body 10, and the weld mark 31 is located in a partial region 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 weld mark 31 is formed on the side of the tab 20 away from the current collector 11, the surface of the current collector 11 away from the tab 20 is not formed with the weld mark 31, and the surface of the current collector 11 away from the tab 20 is a plane. In this way, the weld mark 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 8, the weld 31 penetrates the tab 20 and the current collector 11 in the thickness direction of the pole piece body 10. Because, the welding process has heat accumulation, and along with the welding goes on, the laser penetration can increase gradually, reaches the certain degree after, the penetration exceeds utmost point ear 20 and the thickness sum of mass flow body 11 to it also forms welding seal 31 to deviate from utmost point ear 20 one side at mass flow body 11. At this time, the weld mark 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. The weld mark 31 on the side of the current collector 11 facing away from the tab 20 is covered with the active material layer 12, and the influence of the weld mark 31 on the separator on this side can be reduced. The weld mark 31 on the side of the current collector 11 facing away from the tab 20 protrudes toward the side facing away from the tab 20, thereby forming a second protrusion 312 b.

In other examples, in the same weld mark 31, a part of the weld mark 31 penetrates through the tab 20 and the current collector 11; another portion of the weld mark 31 penetrates the tab 20 and is located in a partial region of the current collector 11 close to the tab 20 in the thickness direction. For example, the seal 31 includes an outer edge portion and an intermediate portion, the outer edge portion being disposed circumferentially outside the intermediate portion. Along the thickness direction of pole piece body, outer fringe portion runs through utmost point ear 20 and current collector 11, and the outer fringe portion orientation that is located current collector 11 and deviates from utmost point ear 20 one side is protruding from one side of utmost point ear 20. In the welding process, the current collector 11 slightly deforms, the compression effect is poor, the defocusing amount of laser welding is gradually reduced, and the welding mark 31 is formed on one side of the current collector 11 departing from the lug 20 at the welding tail end. At this time, the outer edge of the weld mark 31 is visible on the surface of the current collector 11 facing away from the tab 20. The outer edge portion of the current collector 11 on the side facing away from the tab 20 is protruded toward the side facing away from the tab 20, thereby forming a second protrusion 312 b. Here, the outer edge portion of the current collector 11 on the side away from the tab 20 is covered with the active material layer 12, and the influence of the outer edge portion on the separator on that side can be reduced.

Further, the intermediate portion penetrates the tab 20 in the thickness direction of the pole piece body 10, and is located in a partial region close to the tab 20 in the thickness direction of the current collector 11. At this time, the intermediate portion of the weld mark 31 is not visible on the surface of the current collector 11 facing away from the tab 20.

In one weld mark 31, all the outer edge portions may penetrate the tab 20 and the current collector 11. At this time, along the thickness direction of the pole piece body 10, the current collector 11 is overlapped with the outer edge of the pole piece 20 on the side away from the pole piece body 10.

Alternatively, a part of the outer edge portion may penetrate 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 stamp 31 forms the first protrusion 312a on the surface of 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 weld mark 31 forms a second protrusion 312b on the surface of the current collector 11 on the side facing away from the tab 20. At this time, the welding tension between the tab 20 and the current collector 11 is large, and the welding reliability is high.

Wherein the first protrusion 312a and the second protrusion 312b may be oppositely disposed in 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 8, the second protrusion 312b may be disposed opposite an outer helical line (corresponding to one implementation of the outer rim portion) of the first protrusion 312 a. The outer turn of the helix may be the outermost turn of the helix, or the outer turn of the helix may be any one of the turns 311, such as a next outer turn of the helix, located between the outermost turn of the helix and the innermost turn of the helix. At this time, as shown in fig. 7, the second protrusion 312b is shaped approximately in a circular ring shape; alternatively, as shown in fig. 8, the second protrusion 312b is shaped like a circular ring, and has a plurality of break points without protrusions in the middle of the circular ring, where the solder mark 31 does not penetrate through the current collector 11 and is planar, that is, the break points are planar structures of the current collector 11. In other examples, the second protrusion 312b may also be formed at other positions of the solder mark 31, for example, the second protrusion 312b may also be spiral, which is not limited in this application.

In some embodiments, the second protrusions 312b have a protrusion height that is less than or equal to the protrusion height of the first protrusions 312 a. In this way, the second protrusions 312b have 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, in any one turn of the spiral line 311 of the welding mark 31 on the side of the tab 20 away from the current collector 11, 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 projection 312a to the height H of the first projection 312a is 1 or more. 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, 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 easily pierces a separator adjacent to the first protrusion in the battery, thereby affecting the safety of the battery.

The width W of the first protrusion 312a in any one turn of the spiral line 311 of the welding mark 31 on the side of the tab 20 away from the current collector 11 ranges from 0.01mm to 0.2 mm. For example, the width W of the first protrusion may be 0.01mm, 0.05mm, 0.1mm, 0.15mm, 0.2mm, etc., which is not limited in this embodiment. When the width W of the first protrusion is smaller than 0.01mm, the welding area between the tab 20 and the pole piece body 10 at the first protrusion 312a is smaller, and the welding strength is lower. When the width W of the first projection is larger than 0.2mm, the energy input when forming the first projection 312a is high, affecting the active material layer 12 in the vicinity of the solder mark 31.

In any circle of the spiral line 311 of the welding mark 31 on the side of the tab 20 away from the current collector 11, the height H of the first protrusion 312a is less than or equal to 0.1 mm. For example, the height H of the first protrusion 312a may be 0.01mm, 0.03mm, 0.05mm, 0.07mm, 0.09mm, or 0.1mm, which is not limited in the present 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 easily pierces the separator adjacent to the first protrusion in the battery, which may cause short circuit between the positive and negative electrodes of the battery.

The dimensional parameters of the second protrusions 312b may be set with reference to the range of the dimensional parameters of the first protrusions 312a on the side of the current collector 11 facing away from the tab 20. For example, in any one turn of the spiral line 311, the ratio of the width of the second protrusion 312b to the height of the second protrusion 312b is 1 or more; the height of the second protrusion 312b is less than or equal to 0.1 mm; the width of the second protrusions 312b ranges from 0.01mm to 0.2 mm.

As shown in fig. 9 and 10, a plurality of solder marks 31 are provided on the land 30, and the distance (L2 in fig. 9) between the outermost spiral lines 311 of any two adjacent spiral-shaped solder marks 31 may be 5mm or less. I.e. the distance between two solder prints 31. For example, the distance L2 between two adjacent solder marks 31 may be 0.5mm, 1mm, 2mm, 3mm, 4mm, or 5mm, and the like, which is not limited in this embodiment. When the distance L2 between two adjacent welding marks 31 is greater than 5mm, the welding marks 31 in the welding region 30 are more dispersed, the number of welding marks 31 is less, the effective connection area between the tab 20 and the current collector 11 is smaller, and the connection strength between the tab 20 and the current collector 11 is lower.

As shown in fig. 9, a plurality of solder prints 31 may be arranged in a matrix. Wherein, a plurality of solder prints 31 can be arranged in a matrix of rows and columns. The number of rows in the matrix may be 2 rows, 3 rows, 4 rows, 5 rows, 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 in fig. 9, the matrix may be arranged as a 10 row by 4 column matrix with a total of 40 spiral-shaped solder prints 31. The matrix arrangement is beautiful and tidy, and the welding prints 31 are evenly distributed, so that the welding uniformity of the welding area 30 is good.

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 the matrix arranged by each solder mark 31 may be 2, 3, or 4, and the like, and the number of the matrix is not limited in the present application.

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

For example, when the matrix welding print 31 shown in fig. 9 is formed, the tab 20 is first placed in the groove 121, and the tab 20 is pressed by a clamp; laser welding is performed to form a plurality of spiral-shaped weld marks 31. The distance between the spiral center of each solder mark 31 and the outer edge of the outermost spiral line 311 of each solder mark 31 is 0.25mm, the interval between every two adjacent solder marks 31 is 0.5mm, the width W of each first protrusion 312a (in one spiral line 311) is 0.05mm, and the number of the spiral lines 311 is 4. The laser is continuously welded on the surface of the tab 20, the welding time for forming a single welding mark 31 is 0.05s, 10 × 4 welding marks 31 are formed in total, and the area of the welding zone 30 is 3.5mm × 9.5 mm.

In addition, the present embodiment also provides a battery, which may include at least two pole pieces 100 stacked on each other and having opposite polarities, wherein a separator 200 is disposed between every two adjacent pole pieces 100, and the separator 200 is used to prevent the pole pieces 100 having opposite polarities from contacting each other to cause a short circuit of the battery. At least one of the pole pieces 100 is the pole piece 100 of the above-described embodiment.

In this embodiment, as shown in fig. 11, the 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 may be a positive pole piece or a negative pole piece, and correspondingly, the second pole piece 120 may be a negative pole piece or a positive pole piece.

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 functional surface of the first current collector includes a first sub-functional surface and a second sub-functional surface which are oppositely disposed. A first sub-active material layer disposed on the first sub-functional surface, a second sub-active material layer disposed on the second sub-functional surface; a first groove 1211 is formed on the first sub active material layer, and the bottom wall of the first groove 1211 is a first sub-function 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 within the projection of the second 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 separator 200. Thus, when the first groove 1211 is formed, only a portion 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 remained, thereby increasing the energy density of the battery.

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

In other examples, the first protective layer 41 is disposed between the separator 200 adjacent to the first groove 1211 and the second pole piece 120 adjacent to the separator 200. Therefore, the direct contact between the second pole piece 120 adjacent to the diaphragm 200 and the diaphragm 200 can be avoided, and the battery short circuit caused by the direct contact between the burr and the second pole piece 120 after the diaphragm 200 is punctured by the burr can be avoided, so that the safety of the battery can be improved. Here, the first protective layer 41 may be provided on the surface of the diaphragm 200 facing the second pole piece 120, or the first protective layer 41 may be provided on the surface of the second pole piece 120 facing the diaphragm 200.

In other examples, between the separator 200 adjacent to the first groove 1211, and the first tab 21; and the first protective layer 41 is disposed between the separator 200 adjacent to the first groove 1211 and the second pole piece 120 adjacent to the separator 200. That is, two first protective layers 41 may 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 protection layer 41 on the first current collector. Thus, the first protection layer 41 can cover the first groove 1211, and the first groove 1211 and the burr formed on the first tab 21 can be prevented from penetrating the separator 200 to cause a short circuit of the battery.

In some embodiments, the second pole piece 120 includes a second pole ear 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, and the functional surface of the second current collector includes a third sub-functional surface and a fourth sub-functional surface that are oppositely disposed. Wherein a third sub-active material layer is disposed on the third sub-functional surface and a fourth sub-active material layer is disposed on the fourth sub-functional surface. And a second groove is arranged on the third sub active material layer, and the groove bottom wall of the second groove is a 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. The portion of the fourth sub active material layer facing the second groove 1212 is in contact with the adjacent separator 200. In this way, when the second groove 1212 is formed, only a portion 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 the second groove 1212, and the second pole ear 22. In other examples, a second protective layer 42 is disposed between the separator 200 adjacent the second groove 1212 and the first pole piece 110 adjacent the separator 200. In other examples, between the diaphragm 200 adjacent the second groove 1212, and the second pole ear 22; and a 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. Thus, the safety of the battery can be improved, and the principle thereof is similar to that of the first protective layer 41 and will not be described again.

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, so as to prevent the battery from being short-circuited after the second groove 1212 and the burr formed on the second electrode tab 22 pierce the separator 200.

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 an electrochemical battery cell which is arranged in the battery and contains a positive plate and a negative plate, the battery cell is generally not directly used, and the battery for charging/discharging can be formed by arranging the battery cell and a protection circuit together in a battery shell. Since the battery cell is a power storage part in the battery, the quality of the battery cell directly determines the quality of the battery.

The battery cell can be a winding 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. In the winding process, the first pole piece 110, the diaphragm 200 and the second pole piece 120 are wound in the same direction from the winding head end, and finally, a wound battery cell is formed.

In other examples, the laminated 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 the manufacturing process, and a separator 200 is disposed between two adjacent first pole pieces 110 and second pole pieces 120, and finally stacked to form the laminated cell.

It should be noted that the numerical values and numerical ranges related to the embodiments of the present application are approximate values, and there may be a certain range of errors depending on the manufacturing process, and the error may be considered as negligible by those skilled in the art.

Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.

Claims

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; alternatively, the first and second electrodes may be,

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, 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;

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 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 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;

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;

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.