WO2023088430A1

WO2023088430A1 - Electrode assembly and battery

Info

Publication number: WO2023088430A1
Application number: PCT/CN2022/132895
Authority: WO
Inventors: 彭宁
Original assignee: 珠海冠宇电池股份有限公司
Priority date: 2021-11-18
Filing date: 2022-11-18
Publication date: 2023-05-25
Also published as: CN113948826A

Abstract

The present application provides an electrode assembly and a battery. The electrode assembly comprises at least two electrode plates stacked on top of each other and having opposite polarities, a separator is provided between every two adjacent electrode plates, each electrode plate comprises a current collector and an active material layer, and the active material layer covers two opposite surfaces of the current collector; one of the two adjacent electrode plates is provided with a recess, in the electrode plate provided with the recess, the opening of the recess is located on the surface of the side of the active material layer away from the current collector, and the current collector is disposed at the bottom wall of the recess; the other of the two adjacent electrode plates is provided with a relief groove, which is disposed opposite to the recess; a tab is connected to the current collector in the recess, and the projection of the relief groove on the electrode plate having the recess completely covers the tab located in the recess. The relief groove can reduce thickness increase caused by the tab. Therefore, according to the electrode assembly and the battery provided by the present application, the thickness of the electrode assembly can be reduced so as to decrease the volume of the electrode assembly, thereby increasing the energy density of the battery.

Description

Electrode assembly and battery

This application claims the priority of the Chinese patent application with the application number 202111370463.3 and the application title "electrode assembly and battery" filed with the China Patent Office on November 18, 2021, the entire contents of which are incorporated herein by reference.

technical field

The present application relates to the technical field of batteries, in particular to an electrode assembly and a battery.

Background technique

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

In the related art, the electrode assembly includes a pole piece, and a tab is arranged on the pole piece, and the pole piece is electrically connected with an external circuit structure through the tab.

However, the thickness of some regions of the above-mentioned electrode assembly is relatively large, resulting in a low energy density of the battery.

Contents of the invention

In view of the above problems, embodiments of the present application provide an electrode assembly and a battery, which can reduce the thickness of a part of the electrode assembly, thereby increasing the energy density of the battery.

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

The first aspect of the embodiments of the present application provides an electrode assembly, including: at least two pole pieces stacked on top of each other with opposite polarities, a diaphragm is arranged between every two adjacent pole pieces, and the pole piece includes a current collector and an active electrode assembly. a material layer, the active material layer is covered on two opposite surfaces of the current collector;

One of the two adjacent pole pieces is provided with a groove, and in the pole piece provided with the groove, the notch of the groove is located on the surface of the active material layer away from the current collector, and the groove bottom wall of the groove is For the current collector;

The other of the two adjacent pole pieces is provided with an avoidance groove, and the avoidance groove is arranged opposite to the groove;

The current collector in the groove is connected with a pole lug, avoiding the projection of the groove on the pole piece with the groove, and completely covering the pole lug in the groove.

In the electrode assembly provided by the embodiment of the present application, the electrode assembly includes at least two pole pieces stacked on top of each other with opposite polarities, and a diaphragm is arranged between every two adjacent pole pieces to electrically isolate the two adjacent pole pieces . One of the pole pieces is provided with a pole lug, and the other pole piece adjacent to the pole piece is provided with an escape groove, which can reduce the thickness increase caused by the pole lug, thereby reducing the thickness of the electrode assembly to reduce the electrode assembly. increase the energy density of the battery.

In a possible implementation, 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 current collector and a first active material layer, and the first active material layer disposed on two opposite surfaces of the first current collector;

The groove includes a first groove, the avoidance groove includes a first avoidance groove, and the lug includes a first pole lug; the first groove is located on the first pole piece, and the notch of the first groove is located on the side of the first active material layer away from the first pole piece. On one side of the current collector, the groove bottom wall of the first groove is the first current collector, and the first current collector in the first groove is connected to the first tab;

The second pole piece adjacent to the first pole piece is provided with a first avoidance groove, and the first escape groove is arranged opposite to the first groove;

The projection of the first escape groove on the first pole piece completely covers the first pole lug located in the first groove.

In a possible implementation manner, the second pole piece includes a second current collector and a second active material layer, and the second active material layer is disposed on two opposite surfaces of the second current collector;

The groove includes a second groove, the escape groove includes a second avoidance groove, and the tab includes a second tab; the second groove is located on the second pole piece, and the notch of the second groove is located on the second active material layer away from the first pole piece. On one side of the second current collector, the groove bottom wall of the second groove is a second current collector, and the second current collector in the second groove is connected to the second tab;

The first pole piece adjacent to the second pole piece is provided with a second avoidance groove, and the second escape groove is arranged opposite to the second groove;

The projection of the second escape groove on the second pole piece completely covers the second pole lug located in the second groove.

In a possible implementation manner, a protective layer is disposed between the diaphragm adjacent to the tab and the tab, and the protective layer completely covers the groove.

In a possible implementation manner, an isolation layer is provided between the diaphragm adjacent to the avoidance groove and the escape groove, and the isolation layer completely covers the escape groove.

In a possible implementation, the thickness of the lug in the groove is equal to the groove depth of the groove, and part of the diaphragm, part of the protective layer and part of the isolation layer between the avoidance groove and the groove are all inserted in the avoidance groove ;

Or, the thickness of the lug in the groove is greater than the groove depth of the groove, and part of the diaphragm, part of the protective layer, part of the isolation layer and part of the tab located between the escape groove and the groove are all inserted in the avoidance groove.

In a possible implementation manner, in the pole piece provided with grooves, the current collector is welded to the tab to form a weld print, at least part of the weld print is located on the side of the tab away from the current collector, and faces away from the current collector. The directional protrusion of the current collector forms a first protrusion;

For the projection of the groove on the current collector, the active material layer located on the side of the current collector facing away from the groove is within the projection of the current collector.

In a possible implementation manner, in the pole piece provided with the groove, along the thickness direction of the current collector, the welding mark runs through the tab, and the welding mark is located in a part of the area close to the tab in the thickness direction of the current collector;

Or, in the pole piece provided with the groove, along the thickness direction of the current collector, the welding mark runs through the tab and the current collector, and the welding mark on the side of the current collector away from the tab protrudes toward the side away from the tab. The second protrusion, the active material layer on the side of the current collector away from the groove covers the second protrusion;

Or, in the pole piece provided with the groove, the solder mark includes an outer edge part and a middle part, and the outer edge part is arranged outside the middle part;

Along the thickness direction of the current collector, the middle part runs through the tab, and the middle part is located in a part of the area close to the tab in the thickness direction of the current collector;

Along the thickness direction of the current collector, the outer edge part runs through the tab and the current collector. The outer edge of the current collector on the side away from the tab protrudes toward the side away from the tab to form a second protrusion. The active material layer on one side of the groove covers the second protrusion.

In a possible implementation, in the pole piece provided with the avoidance groove:

The length of the escape groove along the first direction of the pole piece ranges from 1mm to 40mm;

And/or, the length of the escape groove along the second direction of the pole piece ranges from 1 mm to 30 mm;

And/or, along the second direction of the pole piece, the escape groove is located in the middle section of the pole piece, and the distance between the avoidance groove and the end of the pole piece is 1/4-3/4 of the length of the pole piece;

And/or, the groove depth range of the avoidance groove is 0.01mm-0.2mm;

Wherein, the first direction is perpendicular to the second direction.

In a possible implementation manner, in the pole piece provided with grooves:

The length of the groove along the first direction of the pole piece ranges from 1 mm to 40 mm;

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

And/or, along the second direction of the pole piece, the groove is located in the middle section of the pole piece, and the distance between the groove and the end of the pole piece is 1/3-2/3 of the length of the pole piece;

And/or, the distance between the tab located in the groove and the active material layer located in the groove ranges from 0.001 mm to 5 mm;

And/or, the thickness range of the tab is 0.01mm-1mm;

And/or, the depth of the groove ranges from 0.01mm to 0.2mm;

Wherein, the first direction is perpendicular to the second direction.

A second aspect of the embodiments of the present application provides a battery, including the electrode assembly in the first aspect above.

In the battery provided in the embodiment of the present application, the battery includes an electrode assembly, and the electrode assembly includes at least two pole pieces stacked on top of each other with opposite polarities, and a separator is arranged between every two adjacent pole pieces to electrically isolate adjacent Two pole pieces. One of the pole pieces is provided with a pole lug, and the other pole piece adjacent to the pole piece is provided with an escape groove, which can reduce the thickness increase caused by the pole lug, thereby reducing the thickness of the electrode assembly to reduce the electrode assembly. increase the energy density of the battery.

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

Description of drawings

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

FIG. 1 is a cross-sectional view of an electrode assembly provided in an embodiment of the present application;

Fig. 2 is a cross-sectional view of a pole piece provided by an embodiment of the present application;

Fig. 3 is a top view of a pole piece provided by the embodiment of the present application;

Fig. 4 is a top view of another pole piece provided by the embodiment of the present application;

Fig. 5 is a top view of another pole piece provided by the embodiment of the present application;

Fig. 6 is a cross-sectional view of another pole piece provided by the embodiment of the present application;

Fig. 7 is a cross-sectional view of another electrode assembly provided by the embodiment of the present application;

Fig. 8 is a cross-sectional view of another electrode assembly provided by the embodiment of the present application;

FIG. 9 is an enlarged structural schematic diagram of part C in FIG. 8 .

Explanation of reference signs:

1- electrode assembly;

100-pole piece;

110-the first pole piece;

120-the second pole piece;

200-diaphragm;

11-collector;

12 - active material layer;

121 - groove;

1211 - first groove;

1212 - second groove;

20-pole ear;

21 - the first pole ear;

22 - the second pole ear;

30 - welding area;

40 - protective layer;

41 - first protective layer;

42 - second protective layer;

50-auxiliary glue layer;

60-avoidance groove;

61-the first avoidance slot;

62-the second avoidance slot;

70 - isolation layer;

71-first isolation layer;

72 - Second isolation layer.

Detailed ways

The electrode assembly includes two pole pieces with opposite polarities, and a diaphragm is arranged between the two adjacent pole pieces to electrically isolate the two adjacent pole pieces. Wherein, a pole lug is connected to the pole piece.

However, the tab has a certain thickness, and in the area where the tab is connected to the pole piece, the thickness of the pole piece increases due to the installation of the tab, resulting in an increase in the thickness of the electrode assembly, and the larger volume of the electrode assembly reduces the energy of the battery density.

In view of the above technical problems, the embodiment of the present application provides an electrode assembly and a battery. The electrode assembly includes at least two pole pieces stacked on top of each other with opposite polarities. Sexually isolates two adjacent pole pieces. One of the pole pieces is provided with a pole lug, and the other pole piece adjacent to the pole piece is provided with an escape groove, which can reduce the thickness increase caused by the pole lug, thereby reducing the thickness of the electrode assembly to reduce the electrode assembly. increase the energy density of the battery.

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

The embodiment of the present application provides a pole piece 100 , as shown in FIGS. 1 and 2 , the pole piece 100 includes a current collector 11 and an active material layer 12 , and the pole piece 100 can be a negative pole piece or a positive pole piece. Specifically, it can be determined according to the specific selection of materials for the current collector 11 and each active material layer 12 . For example, when the current collector 11 is aluminum foil and the material of the active material layer 12 is a positive electrode active material such as a ternary material or lithium iron phosphate, the pole sheet 100 is a positive electrode sheet; the active material layer 12 on the positive electrode sheet is a positive electrode active material layer. When the current collector 11 is copper foil and the material of the active material layer 12 is a negative electrode active material such as graphite or silicon base, the pole sheet 100 is a negative electrode sheet, and the active material layer 12 on the negative electrode sheet is a negative electrode active material layer.

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

As shown in FIG. 1 and FIG. 2 , a groove 121 is provided in the active material layer 12 on one surface of the pole piece, and the groove 121 exposes part of the surface of the current collector 11 . The groove 121 can be formed by cleaning and removing the corresponding part of the active material layer 12 to expose the current collector 11 . Since the active material layer 12 at the groove 121 is removed, the thickness of the electrode assembly can be reduced.

The cleaning method may be laser cleaning, mechanical cleaning, or styrofoam cleaning, and the application does not limit the cleaning method.

A tab 20 is disposed in the groove 121 , and the tab 20 is electrically connected to the exposed surface of the current collector 11 . The surface of the tab 20 away from the current collector 11 is covered with a protective layer 40. The protective layer 40 can prevent the welding burrs formed by the tab 20 and the current collector 11 from piercing the outer film layer of the pole piece 100, causing damage to the performance or performance of the battery. safety impact. Wherein, the protection layer 40 may completely cover the groove 121 .

The active material layer 12 on the side of the current collector 11 facing away from the tab 20 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 on the side of the current collector 11 away from the tab. The active material layer 12 on the 20 side is within the projection on the current collector 11 . That is, the active material layer 12 on the back of the groove 121 is not removed, the exposed area of the current collector 11 is small, and the activity of the pole piece 100 is high.

In some embodiments, as shown in FIG. 3 , a welding zone 30 is formed at the joint between the tab 20 and the current collector 11 , and there may be multiple welding marks in the welding zone 30 , and the plurality of welding marks are arranged at intervals. The input energy for forming a single soldering mark is small, which can reduce the impact on the active material layer 12 near the soldering area 30 .

For example, the tab 20 and the current collector 11 may be connected by laser welding, and the laser is irradiated from the side of the tab 20 away from the current collector 11 for welding.

In some embodiments, the thickness of the protection layer 40 may range from 0.001 mm to 0.1 mm. For example, the thickness of the protective layer 40 can be 0.001mm, 0.005mm, 0.01mm, 0.012mm, 0.05mm or 0.1mm, etc. When the thickness of the protective layer 40 is less than this range, the protective layer 40 is thinner, and the protective effect of the protective layer 40 is poor. When the thickness of the protective layer 40 is greater than this range, the protective layer 40 is thicker and will occupy more internal space of the battery.

In some embodiments, as shown in FIG. 4 , the tab 20 located in the groove 121 has a distance from the active material layer 12 located in the groove 121 . There is a distance between the edge of the tab 20 and the notch edge of the groove 121 to prevent the tab 20 from affecting the active material layer 12 in the groove 121 during the connection process.

Specifically, as shown in FIG. 4 , the distance between the tab 20 located in the groove 121 and the active material layer 12 located in the groove 121 is L1, and the distance L1 may range from 0.001 mm to 5 mm. For example, the distance L1 may be 0.001mm, 0.01mm, 0.05mm, 0.1mm, 0.5mm, 1mm, 3mm or 5mm and so on. In this way, it is avoided that L1 is too small, causing the tab 20 to easily affect the active material layer 12 at the groove 121 during the welding process. It can also avoid that L1 is too large, and more active material layers 12 need to be washed off, which will affect the energy density of the battery.

In some embodiments, the thickness of the current collector 11 may range from 0.001 mm to 0.02 mm. For example, the thickness of the current collector 11 may be 0.001mm, 0.003mm, 0.006mm, 0.01mm, 0.013mm, 0.016mm or 0.02mm, etc., which is not limited in the present application.

It should be noted that, as shown in Figure 4, the width direction of the pole piece 100 can be in the first direction, that is, the direction shown by Y in the figure; the length direction of the pole piece 100 can be in the second direction, that is, the direction shown by X in the figure direction; the first direction and the second direction may be perpendicular to each other. The thickness direction of the pole piece 100 may be consistent with the thickness direction of the tab 20 , the electrode assembly 1 and the battery. The width direction and length direction in the embodiments of the present application are only for the convenience of description, and do not imply any limitation to any size. For example, width may be greater than, less than, or equal to length.

In some embodiments, the groove 121 may be located in the middle section of the current collector 11 in the length direction (ie, the second direction X), and the force received by the two ends of the pole piece 100 at the groove 121 is relatively consistent and balanced. However, if the groove 121 is disposed at the end of the pole piece 100 , the groove 121 receives an uneven force from both ends of the pole piece 100 , so that the active material layer 12 at the groove 121 is easy to fall off.

Specifically, as shown in FIG. 4, the distance between the groove 121 and the lengthwise end of the current collector 11 is L2, the length of the current collector 11 is L3, and the ratio of L2/L3 can be in the range of 1/3-2/ 3. For example, the ratio of L2/L3 can be 1/3, 2/4, 3/5 or 2/3, etc. In this way, it is avoided that L2/L3 is too small or too large, and the groove 121 receives uneven force from both ends of the pole piece 100 .

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 0.01mm, 0.03mm, 0.04mm, 0.05mm, 0.07mm, 0.1mm or 0.2mm. Therefore, the active material layer 12 can be avoided from being too thin, and the energy density of the battery is low. It can also avoid that the active material layer 12 is too thick, the active material layer 12 close to the surface of the current collector 11 cannot be utilized, and the utilization rate of the active material in the active material layer 12 is low.

As shown in FIG. 4 , the length of the groove 121 along the first direction Y of the pole piece 100 is L4, and the range of L4 may be 1mm-40mm. For example, L4 can be 1mm, 2mm, 5mm, 10mm, 15mm, 20mm, 30mm or 40mm, etc. Therefore, it can be avoided that L4 is too small, resulting in a small connectable area between the tab 20 and the current collector 11 . It can also prevent L4 from being too large, and the active material layer 12 will be removed more, which will greatly affect the energy density of the battery.

As shown in FIG. 4 , the length of the groove 121 along the second direction X of the pole piece 100 is L5, and the length L5 may range from 1 mm to 30 mm. For example, L5 can be 1mm, 2mm, 5mm, 10mm, 15mm, 20mm, 25mm or 30mm, etc. Its principle is similar to that of the length value L4 and will not be repeated here.

The thickness of the tab 20 may range from 0.01 mm to 1 mm. For example, the thickness of the tab 20 may be 0.01mm, 0.03mm, 0.05mm, 0.1mm, 0.3mm, 0.5mm, 0.7mm or 1mm. Therefore, it can be avoided that the tab 20 is too thin, the resistance of the tab 20 is large, and the capacity of the tab 20 is poor. It can also prevent the tab 20 from being too thick, which would occupy more internal space of the battery.

The length of the tab 20 along the first direction Y may range from 5 mm to 200 mm. For example, the length of the tab 20 along the first direction Y is 5mm, 10mm, 20mm, 25mm, 50mm, 75mm, 100mm, 150mm or 200mm, etc. Therefore, it can be avoided that the tab 20 is too short, the connection area between the tab 20 and the current collector 11 is small, and the connection strength is low. It can also prevent the tab 20 from being too long, which would occupy more internal space of the battery.

The length of the tab 20 along the second direction X may range from 1 mm to 20 mm. For example, the length of the tab 20 along the second direction X is 1 mm, 5 mm, 6 mm, 10 mm, 15 mm, or 20 mm. Therefore, it is possible to prevent the tab 20 from being too narrow, the area that can be connected between the tab 20 and the current collector 11 is small, and the connection strength is low. It can also prevent the tab 20 from being too wide, which will occupy more internal space of the battery.

As shown in FIG. 3 , an auxiliary adhesive layer 50 may also be provided on the pole piece 100 , and the tab 20 is inserted into the auxiliary adhesive layer 50 . Wherein, after the pole piece 100 is formed into the electrode assembly 1 , the exterior of the electrode assembly 1 can be wrapped with a plastic casing to protect the electrode assembly 1 . The auxiliary adhesive layer 50 can be used to seal (using hot-melt sealing) the gap between the tab 20 and the plastic package.

The electrode assembly 1 provided by the embodiment of the present application will be described in detail below with reference to the accompanying drawings.

The electrode assembly 1 provided in the embodiment of the present application is shown in FIG. 1 and FIG. 7 , and the electrode assembly 1 can be applied in a battery. The electrode assembly 1 may include at least two pole pieces 100 stacked on top of each other with opposite polarities. The pole pieces 100 with opposite polarities respectively form a positive pole piece and a negative pole piece of the battery. In order to avoid contact short circuit between the positive and negative pole pieces, a diaphragm 200 is arranged between every two adjacent pole pieces 100 , and the pole pieces 100 with opposite polarities are electrically isolated by the diaphragm 200 . At least one of the pole pieces 100 may be the pole piece 100 in the above embodiments.

In this embodiment, one of the two adjacent pole pieces 100 is the pole piece 100 in the above embodiment, that is, one of the two adjacent pole pieces 100 is provided with the groove 121 in the above embodiment. The other of the two adjacent pole pieces 100 is provided with an escape groove 60 , and the avoidance groove 60 is disposed opposite to the groove 121 along the thickness direction of the electrode assembly 1 .

Wherein, the openings of the escape groove 60 and the groove 121 can be arranged opposite to each other, or the openings of the avoiding groove 60 and the groove 121 can also be arranged opposite to each other.

It can be realized that the groove 121 can be close to the edge of the pole piece 100 in the width direction, 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 disposed on the outer side of the groove 121 away from the edge. Along the width direction of the pole piece 100 , the length of the groove 121 is smaller than the length of the current collector 11 .

The projection of the escape groove 60 on the pole piece 100 with the groove 121 completely covers the pole lug 20 located in the groove 121 . That is, the part of the tab 20 located in the groove 121 is smaller than the avoidance groove 60, and the avoidance groove 60 can better avoid the tab 20, reducing the thickness increase brought by the tab 20 to the electrode assembly 1, thereby reducing the The volume of the electrode assembly 1 increases the energy density of the battery.

The escape groove 60 can be formed by cleaning and removing the corresponding part of the active material layer 12 to expose the current collector 11 . Since the active material layer 12 at the escape groove 60 is removed, the thickness of the electrode assembly 1 corresponding to the escape groove 60 can be reduced. The cleaning method may be laser cleaning, mechanical cleaning, or styrofoam cleaning, and the application does not limit the cleaning method.

In some embodiments, in the pole piece provided with the avoidance groove 60, the avoidance groove 60 can be located in the middle section of the length direction of the pole piece 100, and the active material layer 12 at the avoidance groove 60 is relatively consistent and consistent with the force at both ends of the pole piece 100. balanced.

As shown in Figures 4-6, the distance between the avoidance groove 60 and the lengthwise end of the pole piece 100 is L6, the length of the pole piece 100 is L3, and the ratio range of L6/L3 can be 1/4-3/ 4. For example, the ratio of L6/L3 can be 1/4, 2/5, 1/2, 3/5 or 3/4. When the ratio of L6/L3 is in this range, the avoidance groove 60 receives the force from both ends of the pole piece 100 relatively uniformly. In addition, as shown in the dotted box B in FIG. 7 , when the ratio of L6/L3 is in this range, the groove 121 and the avoidance groove 60 in the dotted box B are relatively easy to meet the requirements of relative arrangement.

In some embodiments, the depth of the escape groove 60 ranges from 0.01 mm to 0.2 mm. For example, the depth of the escape groove 60 may be 0.01mm, 0.03mm, 0.04mm, 0.05mm, 0.07mm, 0.1mm or 0.2mm. It is similar to the principle of the depth of the groove 121 and will not be repeated here.

As shown in FIG. 4 and FIG. 5 , the length of the escape groove 60 along the first direction Y of the pole piece 100 ranges from 1 mm to 40 mm. For example, the length of the escape groove 60 along the first direction Y of the pole piece 100 may be 1mm, 2mm, 5mm, 10mm, 15mm, 20mm, 30mm or 40mm, etc. Therefore, it can be avoided that the length is too small, and the escape groove 60 cannot avoid the tab 20 well. It can also be avoided that the length is too large, resulting in low activity of the pole piece 100 .

The length of the escape groove 60 along the second direction X of the pole piece 100 ranges from 1 mm to 30 mm. For example, the length of the escape groove 60 along the second direction X of the pole piece 100 may be 1 mm, 2 mm, 5 mm, 10 mm, 15 mm, 25 mm or 30 mm, etc. The principle is similar to the length of the escape groove 60 along the first direction Y of the pole piece 100 , and will not be repeated here.

In some embodiments, as shown in FIG. 7 , a protective layer 40 is provided between the diaphragm 200 adjacent to the tab 20 and the tab, and the protective layer 40 completely covers the groove 121 to prevent the groove 121 from pairing adjacent The effect of the diaphragm 200. Wherein, the protective layer 40 can be disposed on the side of the tab 20 facing the diaphragm 200 , or the protective layer 40 can also be disposed on the side of the diaphragm 200 facing the tab 20 .

In some embodiments, as shown in FIG. 7 , an isolation layer 70 is provided between the diaphragm 200 adjacent to the avoidance groove 60 and the avoidance groove 60 , and the isolation layer 70 completely covers the avoidance groove 60 to prevent the avoidance groove 60 from facing each other. The influence of adjacent diaphragm 200. Wherein, the isolation layer 70 may be disposed on the side of the escape groove 60 facing the diaphragm 200 , or the isolation layer 70 may also be disposed on the side of the diaphragm 200 facing the escape groove 60 .

In some embodiments, the thickness of the isolation layer 70 may range from 0.001 mm to 0.1 mm. For example, the thickness of the isolation layer 70 can be 0.001mm, 0.005mm, 0.01mm, 0.012mm, 0.05mm or 0.1mm, etc. Its principle is similar to the thickness of the protective layer 40 and will not be repeated here.

As shown in the dashed box B in Fig. 7, when the thickness of the lug 20 in the groove 121 is equal to the groove depth of the groove 121, the part of the diaphragm 200 and the part of the protection between the avoidance groove 60 and the groove 121 arranged oppositely Both the layer 40 and part of the isolation layer 70 enter into the escape groove 60 under the extrusion of the tab 20 . In this way, the increase in the thickness of the electrode assembly 1 due to the arrangement of the tabs 20 is avoided, thereby ensuring the energy density of the battery.

In other examples, as shown in the dotted box B in FIG. 7 , when the thickness of the lug 20 in the groove 121 is greater than the depth of the groove 121 , the part of the diaphragm 200 between the opposite avoidance groove 60 and the groove 121 , part of the protective layer 40 , and part of the isolation layer 70 all enter into the escape groove 60 under the extrusion of the tab 20 . In addition, some tabs 20 protrude from the groove 121 and are located in the escape groove 60 . In this way, it is avoided that the thickness of the electrode assembly 1 is increased due to the provision of the tab 20 . In addition, due to the existence of the avoidance groove 60 , the tab 20 can be set thicker, thereby reducing the resistance of the tab 20 and improving the flow capacity of the tab 20 .

In some embodiments, in the pole piece 100 provided with the groove 121, the current collector 11 is welded to the tab 20 to form a weld print, at least part of the weld print is located on the side of the tab 20 facing away from the current collector 11, and Protruding toward the direction away from the current collector 11 forms a first protrusion, the projection of the groove 121 on the current collector 11 , and the active material layer 12 located on the side of the current collector 11 away from the groove 121 is within the projection of the current collector 11 .

In some examples, in the pole piece 100 provided with the groove 121, along the thickness direction of the current collector 11, the welding print runs through the tab 20, and the welding print is located in a part of the area close to the tab 20 in the thickness direction of the current collector 11 . At this time, the welding mark is formed on the side of the tab 20 away from the current collector 11, but no welding mark is formed on the side of the current collector 11 away from the tab 20, and the side of the current collector 11 away from the side of the tab 20 is a plane . In this way, the solder print 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, in the pole piece 100 provided with the groove 121 , along the thickness direction of the current collector 11 , the welding print runs through the tab 20 and the current collector 11 . At this time, welding marks can be observed on the side of the tab 20 facing away from the current collector 11 and the side of the current collector 11 facing away from the tab 20 . Wherein, the solder marks on the side of the current collector 11 away from the tab 20 are covered by the active material layer 12 , which can reduce the impact of the solder marks on the separator on this side. The solder mark on the side of the current collector 11 away from the tab 20 protrudes toward the side away from the tab 20 to form a second protrusion.

In some other examples, in the pole piece 100 provided with the groove 121, in one welding mark, part of the welding mark penetrates the tab 20 and the current collector 11; The thickness direction of the fluid 11 is in a partial area close to the tab 20 . For example, the solder print includes an outer edge portion and a middle portion, and the outer edge portion is arranged around the outer side of the middle portion. Along the thickness direction of the current collector 11 , the outer edge passes through the tab 20 and the current collector 11 , and the outer edge of the current collector 11 on the side away from the tab 20 protrudes toward the side away from the tab 20 . At this time, the outer edge of the solder mark can be observed on the surface of the current collector 11 facing away from the tab 20 . The outer edge of the current collector 11 on the side away from the tab 20 protrudes toward the side away from the tab 20 to form a second protrusion. Wherein, the outer edge portion of the current collector 11 on the side away from the tab 20 is covered by the active material layer 12 , which can reduce the influence of the outer edge portion on the separator on this side.

Along the thickness direction of the current collector 11 , the middle portion passes through the tab 20 , and the middle portion is located in a partial area of the current collector 11 close to the tab 20 in the thickness direction. At this time, the middle part of the solder mark cannot be observed on the surface of the current collector 11 facing away from the tab 20 .

In specific implementation, the at least two pole pieces 100 may include a first pole piece 110 and a second pole piece 120 , and the polarities of the first pole piece 110 and the second pole piece 120 are opposite. One of the first pole piece 110 and the second pole piece 120 is used to form a positive pole piece, and the other one of the first pole piece 110 and the second pole piece 120 is used to form a negative pole piece.

The first pole piece 110 and the second pole piece 120 are stacked on each other. In order to avoid a short circuit between the first pole piece 110 and the second pole piece 120, the diaphragm 200 is arranged between the adjacent first pole piece 110 and the second pole piece 120, and the diaphragm 200 is used to connect the first pole piece 110 and the second pole piece 120. The second pole piece 120 is electrically insulated.

In some examples, the electrode assembly 1 may be a wound electrode assembly 1 . Wherein, the first pole piece 110 and the second pole piece 120 are both one, and the first pole piece 110, the separator 200 and the second pole piece 120 stacked in sequence are wound around the winding center to form a winding structure.

In other examples, the electrode assembly 1 may be a laminated electrode assembly 1 . Wherein, there are multiple first pole pieces 110, multiple second pole pieces 120, multiple first pole pieces 110 and multiple second pole pieces 120 are sequentially stacked and arranged along the same direction, and each adjacent first pole piece A diaphragm 200 is disposed between the pole piece 110 and the second pole piece 120 to electrically insulate the first pole piece 110 and the second pole piece 120 .

The embodiment of the present application takes the wound electrode assembly 1 as an example for detailed description.

In some embodiments, as shown in FIG. 8 and FIG. 9 , in some examples, the first pole piece 110 includes a first current collector and a first active material layer, and the first active material layer is arranged on two opposite sides of the first current collector. On the surface.

In some examples, the second pole piece 120 includes a second current collector and a second active material layer, and the second active material layer is disposed on two opposite surfaces of the second current collector.

In some other examples, the groove 121 may include the first groove 1211 , the escape groove 60 includes the first avoidance groove 61 , and the tab 20 includes the first tab 21 .

In some other examples, the groove 121 includes the second groove 1212 , the escape groove 60 includes the second avoidance groove 62 , and the tab 20 includes the second tab 22 .

The first pole piece 110 is provided with a first groove 1211, the first groove 1211 exposes the surface of the first current collector, and the notch of the first groove 1211 is located on the side of the first active material layer away from the first current collector. On the surface, the groove bottom wall of the first groove 1211 is the first current collector. The current collector 11 in the first groove 1211 is connected to the first tab 21 . Wherein, the second pole piece 120 adjacent to the first pole piece 110 is provided with a first escape groove 61, and the first escape groove 61 is located in the second active material layer of the second pole piece 120 close to the first groove 1211 , the first escape groove 61 is disposed opposite to the first groove 1211 along the thickness direction of the electrode assembly 1 . The first escape groove 61 can reduce the thickness of part of the electrode assembly 1 to ensure the energy density of the battery.

The projection of the first escape groove 61 on the first pole piece 110 completely covers the first tab 21 located in the first groove 1211 , thereby forming a better avoidance effect on the first tab 21 .

In the first pole piece 110 , a first protective layer 41 is provided on the side of the first tab 21 facing away from the first current collector, so as to protect the adjacent diaphragm 200 . Wherein, the first protective layer 41 may be located on the surface of the first tab 21 facing away from the first current collector, or the first protective layer 41 may be located on the side of the diaphragm 200 adjacent to the first tab 21 facing the first The face on one side of the tab 21.

Wherein, the first protective layer 41 completely covers the first groove 1211 .

A first isolation layer 71 is provided between the diaphragm 200 adjacent to the first escape groove 61 and the first escape groove 61 , so as to protect the adjacent diaphragm 200 . The first isolation layer 71 may be located on the surface of the first avoidance groove 61 facing the first groove 1211 , or the first isolation layer 71 may be located on the side of the diaphragm 200 adjacent to the first escape groove 61 close to the first groove 1211 . A surface on one side of the escape groove 61 .

Wherein, the first isolation layer 71 completely covers the first escape groove 61 .

In some embodiments, as shown in FIG. 8, the second pole piece 120 is provided with a second groove 1212, the second groove 1212 exposes the surface of the second current collector, and the notch of the second groove 1212 is located in the second On the surface of the active material layer facing away from the second current collector, the bottom wall of the second groove 1212 is the second current collector. The second current collector in the second groove 1212 is connected to the second tab 22 . Wherein, the first pole piece 110 adjacent to the second pole piece 120 is provided with a second escape groove 62, and the second escape groove 62 is located in the first active material layer of the first pole piece 110 close to the second groove 1212 , the second avoidance groove 62 is disposed opposite to the second groove 1212 along the thickness direction of the electrode assembly 1 . The second escape groove 62 can reduce the thickness of part of the electrode assembly 1 to ensure the energy density of the battery.

The projection of the second escape groove 62 on the second pole piece 120 completely covers the second tab 22 located in the second groove 1212 , thereby forming a better avoidance effect on the second tab 22 .

In the second pole piece 120 , a second protective layer 42 is provided on the side of the second tab 22 facing away from the second current collector, so as to protect the adjacent diaphragm 200 . Wherein, the second protective layer 42 may be located on the side of the second tab 22 facing away from the second current collector, or the second protective layer 42 may be located on the side of the diaphragm 200 adjacent to the second tab 22 toward the second The face on one side of the tab 22 .

Wherein, the second protective layer 42 completely covers the second groove 1212 .

A second isolation layer 72 is provided between the diaphragm 200 adjacent to the second escape groove 62 and the second avoidance groove 62 , so as to protect the adjacent diaphragm 200 . The second isolation layer 72 may be located on the side of the second avoidance groove 62 facing the second groove 1212 , or the second isolation layer 72 may be located on the side of the diaphragm 200 adjacent to the second avoidance groove 62 close to the first Two escape grooves 62 on one side.

Wherein, the second isolation layer 72 completely covers the second escape groove 62 .

It should be noted that, in the embodiment of the present application, the first groove 1211 may be provided only on the first pole piece 110, or the second groove 1212 may be provided only on the second pole piece 120, or, A first groove 1211 is set on the piece 110 , and a second groove 1212 is set on the second pole piece 120 . The embodiment of the present application does not limit the arrangement of the first groove 1211 and the second groove 1212 .

In addition, the first avoidance groove 61 may be provided only on the second pole piece 120; or, the second avoidance groove 62 may be provided only on the first pole piece 110; or, the first avoidance groove may be provided on the second pole piece 120 61, and at the same time, a second escape groove 62 is provided on the first pole piece 110. The embodiment of the present application does not limit the arrangement of the first avoidance groove 61 and the second escape groove 62 .

In addition, the embodiment of the present application also provides a battery, which includes the electrode assembly 1 in the above embodiment.

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

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

Claims

An electrode assembly, characterized in that it comprises: at least two pole pieces stacked on top of each other with opposite polarities, a diaphragm is arranged between every two adjacent pole pieces, and the pole piece includes a current collector and an active material layer, the active material layer is covered on two opposite surfaces of the current collector;

One of the two adjacent pole pieces is provided with a groove, and in the pole piece provided with the groove, the notch of the groove is located on the side of the active material layer away from the current collector On one side, the groove bottom wall of the groove is the current collector;

The other of the two adjacent pole pieces is provided with an avoidance groove, and the avoidance groove is arranged opposite to the groove;

The current collector in the groove is connected with a tab, and the projection of the escape groove on the pole piece with the groove completely covers the tab located in the groove.
The electrode assembly according to claim 1, wherein at least two of the pole pieces comprise a first pole piece and a second pole piece with opposite polarities, and the first pole piece comprises a first current collector and a first pole piece. an active material layer, the first active material layer is disposed on two opposite surfaces of the first current collector;

The groove includes a first groove, the escape groove includes a first avoidance groove, and the tab includes a first tab; the first groove is located on the first pole piece, and the first groove The notch is located on the surface of the first active material layer facing away from the first current collector, the bottom wall of the first groove is the first current collector, and in the first groove The first current collector is connected to the first tab;

The second pole piece adjacent to the first pole piece is provided with the first escape groove, and the first escape groove is opposite to the first groove;

The projection of the first escape groove on the first pole piece completely covers the first tab located in the first groove.
The electrode assembly according to claim 2, wherein the second pole piece comprises a second current collector and a second active material layer, and the second active material layer is disposed on opposite sides of the second current collector. on the surface;

The groove includes a second groove, the avoidance groove includes a second avoidance groove, and the tab includes a second tab; the second groove is located on the second pole piece, and the second groove The notch is located on the surface of the second active material layer facing away from the second current collector, the bottom wall of the second groove is the second current collector, and the second groove in the second groove The second current collector is connected to the second tab;

The first pole piece adjacent to the second pole piece is provided with the second avoidance groove, and the second escape groove is opposite to the second groove;

The projection of the second escape groove on the second pole piece completely covers the second tab located in the second groove.
The electrode assembly according to any one of claims 1-3, wherein a protective layer is provided between the diaphragm adjacent to the tab and the tab, and the protective layer completely covers the tab. groove.
The electrode assembly according to claim 4, wherein an isolation layer is provided between the diaphragm adjacent to the avoidance groove and the escape groove, and the isolation layer completely covers the escape groove.
The electrode assembly according to claim 5, wherein the thickness of the tab in the groove is equal to the groove depth of the groove, and the portion between the escape groove and the groove is The diaphragm, part of the protective layer and part of the isolation layer are all inserted in the avoidance groove;

Or, the thickness of the lug in the groove is greater than the groove depth of the groove, and part of the diaphragm, part of the protective layer, and part of the isolation layer between the escape groove and the groove And part of the tabs are inserted into the escape groove.
The electrode assembly according to any one of claims 1-3, characterized in that, in the pole piece provided with the groove, the current collector is welded to the tab to form a welding mark, at least part of the The welding mark is located on the side of the tab away from the current collector, and protrudes toward the direction away from the current collector to form a first protrusion;

For the projection of the groove on the current collector, the active material layer located on the side of the current collector away from the groove is within the projection of the current collector.
The electrode assembly according to claim 7, characterized in that, in the pole piece provided with the groove, along the thickness direction of the current collector, the welding print runs through the tab, and the The welding mark is located in a partial area close to the tab in the thickness direction of the current collector;

Or, in the pole piece provided with the groove, along the thickness direction of the current collector, the welding print runs through the tab and the current collector, and is located on the side of the current collector away from the pole. The solder mark on the side of the ear protrudes toward the side away from the tab to form a second protrusion, and the active material layer on the side of the current collector away from the groove covers the second protrusion ;

Or, in the pole piece provided with the groove, the solder mark includes an outer edge portion and a middle portion, and the outer edge portion is arranged on the outer side of the middle portion; along the thickness of the current collector direction, the middle portion runs through the tab, and the middle portion is located in a partial area close to the tab in the thickness direction of the current collector; along the thickness direction of the current collector, the outer edge portion Through the tab and the current collector, the outer edge of the current collector on the side away from the tab protrudes toward the side away from the tab to form a second protrusion. The active material layer on the side of the fluid away from the groove covers the second protrusion.
The electrode assembly according to any one of claims 1-3, characterized in that,

In the pole piece provided with the escape groove:

The length of the escape groove along the first direction of the pole piece ranges from 1 mm to 40 mm;

And/or, the length of the escape groove along the second direction of the pole piece ranges from 1 mm to 30 mm;

And/or, along the second direction of the pole piece, the escape groove is located in the middle section of the pole piece, and the distance between the escape groove and the end of the pole piece is the length of the pole piece 1/4-3/4 of;

And/or, the groove depth range of the avoidance groove is 0.01mm-0.2mm;

Wherein, the first direction is perpendicular to the second direction.
The electrode assembly according to any one of claims 1-3, wherein, in the pole piece provided with the groove:

The length of the groove along the first direction of the pole piece ranges from 1 mm to 40 mm;

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

And/or, along the second direction of the pole piece, the groove is located in the middle section of the pole piece, and the distance between the groove and the end of the pole piece is the length of the pole piece 1/3-2/3 of;

And/or, the distance between the tab located in the groove and the active material layer located in the groove ranges from 0.001 mm to 5 mm;

And/or, the thickness range of the tab is 0.01mm-1mm;

And/or, the groove depth range of the groove is 0.01mm-0.2mm;

Wherein, the first direction is perpendicular to the second direction.
A battery, characterized by comprising the electrode assembly described in any one of claims 1-10 above.