CN111370641B

CN111370641B - Electrode assembly, battery using same and electric device

Info

Publication number: CN111370641B
Application number: CN202010214566.XA
Authority: CN
Inventors: 王佳伟; 李�瑞; 江行国; 连旭宸
Original assignee: Ningde Amperex Technology Ltd
Current assignee: Ningde Amperex Technology Ltd
Priority date: 2020-03-24
Filing date: 2020-03-24
Publication date: 2021-09-21
Anticipated expiration: 2040-03-24
Also published as: CN111370641A

Abstract

An electrode assembly comprises a first pole piece, wherein the first pole piece comprises a first current collector, the first current collector comprises a first area, a second area and a third area, the second area and the third area are formed by extending the first area to two different directions, the boundary line of the first area and the second area is a first boundary line, and the boundary line of the first area and the third area is a second boundary line; a first active layer disposed on a surface of the first current collector; an opening region penetrating the electrode assembly; the buffer area is connected with the opening area, the surface of the first pole piece positioned in the buffer area is not provided with the first active layer, and at least part of the first area is positioned in the buffer area and overlapped. The application also provides a battery and an electric device using the electrode assembly.

Description

Electrode assembly, battery using same and electric device

Technical Field

The present disclosure relates to the field of energy storage technologies, and particularly, to an electrode assembly, a battery using the electrode assembly, and an electric device using the electrode assembly.

Background

The soft package battery is a polymer battery packaged by an aluminum-plastic film, is usually a lithium polymer battery, is mainly used for electric devices such as mobile phones and tablet computers, and is gradually valued along with the development of the electronic industry. The existing special-shaped batteries, such as L-shaped batteries, have relatively weak relative strength due to the fact that the external dimension of the pole piece is suddenly changed at some places, which causes stress concentration at the position. Moreover, when the battery is impacted, the positions are easy to break after being impacted, and more fragments are generated at the broken positions to further cause short-circuit combustion of the battery.

To address this problem, the prior art generally employs two approaches to improve: (1) the heat dissipation is accelerated, and a local combustion failure mode caused by the fact that the heat of the battery is concentrated and cannot be quickly released is avoided; (2) reducing the fracture fragments reduces the risk of short circuits. To solution (1) accelerate the heat dissipation often need improve battery heat radiation structure, can make whole cost rise, though this scheme can avoid breaking the back and take place violent burning as far as possible, can not reduce the battery and receive the risk that takes place the short circuit after the striking. For the solution (2), the hardness of the battery is further enhanced by increasing the thickness of the base material, so that the battery forms complete fracture when being impacted, and the secondary short circuit combustion risk caused by fragments is reduced; however, the increase in the thickness of the substrate increases the quality of the battery, increases the cost, and decreases the energy density of the battery.

How to solve the above problems needs to be considered by those skilled in the art.

Disclosure of Invention

In order to solve the problems that short circuit is easy to occur due to impact, the thickness of a base material is increased, the impact resistance is improved, but the energy density is reduced in the prior art, the embodiment of the application provides an electrode assembly, the short circuit risk can be reduced under the condition that the energy density is not sacrificed, and the application also provides a battery and an electric device applying the electrode assembly.

An electrode assembly, comprising:

a first pole piece, the first pole piece comprising,

the current collector comprises a first area, a second area and a third area, wherein the second area and the third area are formed by extending the first area to two different directions, the boundary line of the first area and the second area is a first boundary line, and the boundary line of the first area and the third area is a second boundary line;

a first active layer disposed on the first current collector surface;

an open region extending through the electrode assembly; and

the buffer area is connected with the opening area, the surface of the first pole piece positioned in the buffer area is not provided with the first active layer, and at least part of the first area is positioned in the buffer area and overlapped.

The first area is an area with a high concentration probability of the resultant force of the external force when the first pole piece is impacted by the external force, and the area where the first area is overlapped with the buffer area is an area where the first pole piece is easy to break when the first pole piece is impacted by the external force, so that the first active layer is not arranged on the surface of the first pole piece located in the buffer area, the first active material layer fragments generated when the first pole piece breaks can be avoided, and the short circuit risk is further reduced.

Further, the shape of the opening area is at least a part of a circle, the center of the opening area is the intersection point of the first intersection line and the second intersection line, the radius of the opening area is R, the width of the second area in the direction of the first intersection line is La, and the width of the third area in the direction of the second intersection line is Lb. The circular opening area can avoid stress from concentrating at the inner folding angle of the L-shaped battery, avoid the breakage of the opening area and avoid the generation of fragments and short circuits.

Further, the buffer area includes a first buffer area, the first buffer area corresponds to the first pole piece, at least a portion of the first buffer area overlaps with the first intersection line, the first buffer area includes a first edge and a second edge, the first edge is close to the second area, a set of side lengths of the first edge is [ La-2R, La ], the second edge is far from the second area, and a set of side lengths of the second edge is [ La-R, La + R ]. The first buffer area is overlapped with the first intersection line, the first buffer area is arranged corresponding to the easily-broken area of the first pole piece, the first buffer area changes according to the change of the shape, the size and the position of the opening area, and the side length values of the first edge and the second edge can effectively cover more possible easily-broken areas in the set.

Further, the buffer area includes a second buffer area, the second buffer area corresponds to the first pole piece, at least a portion of the second buffer area overlaps with the second intersection line, the second buffer area includes a third side and a fourth side, the third side is close to the third area, a set of side lengths of the third side is [ Lb-2R, Lb ], the fourth side is far away from the third area, and a set of side lengths of the fourth side is [ Lb-R, Lb + R ]. The second buffer area is overlapped with the second intersection line, the second buffer area is arranged corresponding to the easily-broken area of the first pole piece, the second buffer area changes according to the change of the shape, the size and the position of the opening area, and the side length values of the third side and the fourth side can effectively cover more possible easily-broken areas in the set.

Further, the electrode assembly further includes a second pole piece, the second pole piece including:

the second current collector comprises a fourth area, a fifth area and a sixth area, wherein the fifth area and the sixth area are formed by extending the fourth area to two different directions;

a second active layer disposed on the second current collector surface.

The fourth area is an area with a high concentration probability of the resultant force of the external force when the second pole piece is impacted by the external force, and the area where the fourth area is overlapped with the buffer area is an area where the second pole piece is easy to break when the second pole piece is impacted by the external force, so that the second active layer is not arranged on the surface of the second pole piece located in the buffer area, second active material layer fragments generated when the second pole piece breaks can be avoided, and the short circuit risk is further reduced.

Further, the buffer regions further include a third buffer region and a fourth buffer region, the third buffer region and the fourth buffer region correspond to the second pole piece, the third buffer region at least partially overlaps the first buffer region, the first buffer region has a width of L1, the third buffer region has a width of L2, L1-L2 [ -1mm, 1mm ], the fourth buffer region at least partially overlaps the third buffer region, the second buffer region has a width of W1, the fourth buffer region has a width of W2, and the W1-W2 [ -1mm, 1mm ]. The area of first pole piece is inequality with the area of second pole piece, if first pole piece is the negative pole and the second pole piece is the positive pole, in the direction of the thickness direction of perpendicular to electrode subassembly, the area of second active layer is greater than the area of first active layer, in two pole pieces that set up relatively, the area of positive pole active layer is greater than the area of negative pole active layer, and the negative pole active layer is just must be provided with the positive pole active layer to the region, can avoid the electric cycle in-process to produce on the negative pole active layer and analyse lithium, the promotion performance.

Further, electrode subassembly still includes the articulamentum, first pole piece with the second pole piece overlapping sets up, the articulamentum set up in the buffer, the articulamentum with first mass flow body reaches the second mass flow body is connected. The connecting layer is used for fixedly connecting the adjacent first current collector and the second current collector, or connecting the first pole piece and the second pole piece with other elements (such as a battery packaging bag) outside the electrode assembly, so that the strength of the electrode assembly is enhanced, the risk of breakage of the electrode assembly when being impacted by external force is reduced, the section uniformity is improved when the electrode assembly is broken, breakpoints are reduced, and the risks of short circuit and combustion failure are reduced.

Further, the electrode assembly further comprises a heat resistance layer, the first pole piece and the second pole piece are arranged in an overlapped mode, the heat resistance layer is arranged in the buffer area, and the heat resistance layer is arranged on the surfaces of the first current collector and the second current collector. The heat resistance layer can be made of high polymer materials with high toughness and high heat conductivity coefficient, and can increase the strength and the heat conduction efficiency of the first current collector and the second current collector, reduce the short circuit probability and relieve the combustion failure caused by heat concentration.

Further, the first pole piece is a cathode, the second pole piece is an anode, and the second active layer is arranged on the surface of the second current collector located in the buffer area. The buffer zone corresponding to the cathode is provided with an active layer, but because the internal resistance of the cathode active layer is larger, the formula I (V/R) and Q (I) RT) show that when short circuit occurs, the cathode active layer with larger internal resistance can reduce the heat generated under the condition of short circuit, and reduce the risk of combustion failure.

A battery includes the aforementioned electrode assembly.

An electric device comprises the battery.

Compared with the prior art, the electrode assembly has the advantages that the first area is the area with the larger concentration probability of the resultant force of the external force when the first pole piece is impacted by the external force, the area overlapped with the buffer area is the area where the first pole piece is easy to break when impacted by the external force, the first pole piece surface of the buffer area is not provided with the first active layer, the fragments of the first active material layer generated when the first pole piece breaks can be avoided, and the risks of short circuit and combustion failure are reduced.

Drawings

Fig. 1 is a perspective view schematically illustrating an electrode assembly according to a first embodiment of the present application.

Fig. 2 is a schematic sectional view of the electrode assembly of the first embodiment of the present application along the direction II-II.

Fig. 3 is a plan view of a first pole piece of an electrode assembly according to a first embodiment of the present application.

Fig. 4 is a plan view schematically illustrating a second electrode sheet of the electrode assembly according to the first embodiment of the present application.

Fig. 5 is a schematic cross-sectional view of an electrode assembly according to a first embodiment of the present application.

Fig. 6 is a schematic cross-sectional view of an electrode assembly according to a first embodiment of the present application.

Fig. 7 is a schematic cross-sectional view of an electrode assembly according to a first embodiment of the present application.

Fig. 8 is a schematic cross-sectional view of an electrode assembly according to a first embodiment of the present application.

Fig. 9 is a schematic plan view of a battery according to a second embodiment of the present application.

Fig. 10 is a perspective view of an electric device according to a third embodiment of the present application.

Description of the main elements

Power utilization device 100

Body 101

Packaging bag 102

Battery 1

Electrode assembly 10

First pole piece 11

First current collector 110

First active layer 119

First region 111

Second region 112

Third region 113

First intersection 115

Second intersection 116

Second pole piece 12

Second current collector 120

Second active layer 129

Fourth region 121

Fifth region 122

Sixth area 123

Third intersection line 125

Fourth intersection line 126

Open area 13

Center of a circle 130

Buffer 14

First buffer 141

Second buffer 142

Third buffer 143

Fourth buffer 144

Isolation film 15

Connecting layer 16

Thermal barrier 18

The following detailed description will further illustrate the present application in conjunction with the above-described figures.

Detailed Description

The following description will refer to the accompanying drawings to more fully describe the present disclosure. There is shown in the drawings exemplary embodiments of the present application. This application may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. These exemplary embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like reference numerals designate identical or similar components.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, as used herein, the terms "comprises," "comprising," "includes" and/or "including" or "having" and/or "having," integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Furthermore, unless otherwise defined herein, terms such as those defined in commonly used dictionaries should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present application and will not be interpreted in an idealized or overly formal sense.

The following description of exemplary embodiments refers to the accompanying drawings. It should be noted that the components depicted in the referenced drawings are not necessarily shown to scale; and the same or similar components will be given the same or similar reference numerals or similar terms.

Embodiments of the present application will now be described in further detail with reference to the accompanying drawings.

First embodiment

As shown in fig. 1 and 2, the present application provides an electrode assembly 10 including a first pole piece 11, a second pole piece 12, an opening region 13, a buffer region 14, and a separation film 15. The first and

second pole pieces

11 and 12 are spaced apart from each other, the separator 15 is disposed between the first and

second pole pieces

11 and 12, the opening region 13 penetrates the electrode assembly 10, and the buffer region 14 is connected to the opening region 13.

As shown in fig. 3, the first electrode sheet 11 includes a first current collector 110 and a first active layer 119, and the first active layer 119 is disposed on a surface of the first current collector 110. The first current collector 110 includes a first region 111, a second region 112, and a third region 113, and the second region 112 and the third region 113 are formed by extending the first region 111 in two different directions. The boundary between the first region 111 and the second region 112 is a first boundary 115, and the boundary between the first region 111 and the third region 113 is a second boundary 116. The first region 111 is a region where the probability of the resultant force of the external force on the first pole piece 11 is the largest when the electrode assembly 10 is impacted by the external force (for example, an impact or a drop).

In an embodiment, the first pole piece 11 is L-shaped, the first region 111 is disposed in a bevel region of the L-shaped first pole piece 11, and the second region 112 and the third region 113 are disposed in two regions of the L-shaped first pole piece 11 extending in two different directions.

In one embodiment, the open area 13 extends through the inside corner of the L-shaped electrode assembly 10. The shape of the opening area 13 is at least a portion of a circle, the center 130 of the opening area 13 is the intersection point of the first intersection line 115 and the second intersection line 116, or the perpendicular line segments of the center 130 toward the two long sides of the L-shaped first pole piece 11 are the first intersection line 115 and the second intersection line 116, respectively. The boundary line of the first pole piece 11 is a straight line passing through the center 130 of the open area 13. The radius of the opening region 13 is R, the width of the second region 112 in the direction along the first intersection line 115 is La, and the width of the third region 113 in the direction along the second intersection line 116 is Lb. The opening region 13 is disposed at the inner corner of the L-shaped electrode assembly 10, so as to prevent the stress concentration at the inner corner from causing fragments and short circuits.

The buffer region 14 includes a first buffer region 141 and a second buffer region 142, the first buffer region 141 and the second buffer region 142 are located on the first pole piece 11, the first active layer 119 is not disposed on the surface of the first pole piece 11 located in the buffer region 14, and at least a portion of the first region 111 overlaps with the buffer region 14. In an embodiment, the first buffer area 141 is a region where resultant force or stress is concentrated at a junction of the first area 111 and the second area 112, the second buffer area 142 is a region where resultant force or stress is concentrated at a junction of the first area 111 and the third area 113, and the first active layer 119 is not disposed on the surface of the first pole piece 11 of the buffer area 14, so that the first active layer 119 can be prevented from being broken to generate fragments due to external force concentrated on the buffer area 14, and short circuit and thermal failure caused by the fragments can be further avoided.

In one embodiment, at least a portion of the first buffer area 141 overlaps the first intersection line 115, the first buffer area 141 includes a first edge 1411 and a second edge 1412, the first edge 1411 is close to the second region 112, a set of edge lengths of the first edge 1411 is [ La-2R, La ], the second edge 1412 is far from the second region 112, and a set of edge lengths of the second edge 1412 is [ La-R, La + R ]. One end of the first buffer area 141 is connected to the opening area 13, and the lengths of the two sides of the first buffer area 141 connected to the opening area 13 are different.

In an embodiment, at least a portion of the second buffer area 142 overlaps the second intersection line 116, the second buffer area 142 includes a third side 1421 and a fourth side 1422, the third side 1421 is close to the third area 113, a set of side lengths of the third side 1421 is [ Lb-2R, Lb ], the fourth side 1422 is far from the third area 113, and a set of side lengths of the fourth side 1422 is [ Lb-R, Lb + R ]. One end of the second buffer area 142 is connected to the opening area 13, and the lengths of both sides of the second buffer area 142 connected to the opening area 13 are different.

As shown in fig. 4, the second electrode sheet 12 includes a second current collector 120 and a second active layer 129, and the second active layer 129 is disposed on the surface of the second current collector 120.

The second current collector 120 includes a fourth region 121, a fifth region 122, and a sixth region 123, and the fifth region 122 and the sixth region 123 are formed by extending the fourth region 121 in two different directions. The boundary between the fourth area 121 and the fifth area 122 is a third boundary 125, and the boundary between the fourth area 121 and the sixth area 123 is a fourth boundary 126. The fourth region 121 is a region where the probability of the resultant force of the external force on the second pole piece 12 is the largest when the electrode assembly 10 is impacted by the external force (for example, an impact or a drop).

In an embodiment, the second pole piece 12 is L-shaped, the fourth region 121 is disposed in a corner region of the L-shaped second pole piece 12, and the fifth region 122 and the sixth region 123 are disposed in two regions of the L-shaped second pole piece 12 extending in two different directions.

In an embodiment, the buffer region 14 further includes a third buffer region 143 and a fourth buffer region 144, and the third buffer region 143 and the fourth buffer region 144 are disposed on the second pole piece 12. In an embodiment, the third buffer area 143 is a region where the resultant force or the stress is concentrated at the boundary between the fourth area 121 and the fifth area 122, the fourth buffer area 144 is a region where the resultant force or the stress is concentrated at the boundary between the fourth area 121 and the sixth area 123, and the second active layer 129 is not disposed on the surface of the second pole piece 12 of the buffer area 14, so that the second active layer 129 is prevented from being broken to generate fragments due to the concentrated external force acting on the buffer area 14, and short circuit and thermal failure caused by the fragments are further prevented.

In one embodiment, the first pole piece 11 and the second pole piece 12 at least partially overlap in a thickness direction of the electrode assembly 10, and specifically, the first pole piece 11 and the second pole piece 12 may be stacked or wound. The third buffer area 143 at least partially overlaps the first buffer area 141, the first buffer area 141 has a width L1, the third buffer area 143 has a width L2, L1-L2 [ -1mm, 1mm ], the fourth buffer area 144 at least partially overlaps the second buffer area 142, the second buffer area 142 has a width W1, the fourth buffer area 144 has a width W2, and W1-W2 [ -1mm, 1mm ]. In other embodiments, the third buffer region 143 completely overlaps the first buffer region 141 in the thickness direction of the electrode assembly 10, and the fourth buffer region 144 completely overlaps the second buffer region 142 in the thickness direction of the electrode assembly 10.

As shown in fig. 5, in an embodiment, the areas of the first pole piece 11 and the second pole piece 12 are different, the first pole piece 11 can be a cathode, the second pole piece 12 can be an anode, and the area of the second active layer 129 is larger than the area of the first active layer 119 in the direction perpendicular to the thickness direction of the electrode assembly 10, that is, in the two pole pieces which are oppositely disposed, the area of the anode active layer is larger than the area of the cathode active layer, and the anode active layer is disposed in the region directly opposite to the cathode active layer, so that lithium deposition on the cathode active layer during the electrical cycle process can be avoided, and the performance can be improved.

As shown in fig. 6, in an embodiment, the electrode assembly 10 further includes a connection layer 16, the first pole piece 11 and the second pole piece 12 are stacked or overlapped, the connection layer 16 is disposed in the buffer area 14, and the connection layer 16 is connected to the first current collector 110 and the second current collector 120. The connection layer 16 may be an adhesive material, specifically, may be an insulating green tape, a polymer binder, and the like, the connection layer 16 is disposed between the first electrode plate 11 and the second electrode plate 12 and disposed in the buffer region 14, the connection layer 16 fixedly connects the adjacent first current collector 110 and the second current collector 120, or connects the first electrode plate 11 and the second electrode plate 12 with other elements (for example, a battery packaging bag) outside the electrode assembly 10, so as to enhance the strength of the electrode assembly 10, reduce the risk of fracture when the electrode assembly 10 is impacted by an external force, improve the regularity of the fracture when the electrode assembly 10 is fractured, reduce the breaking points, and reduce the risk of short circuit and combustion failure.

As shown in fig. 7, in an embodiment, the electrode assembly 10 may further include a thermal barrier layer 18, the first pole piece 11 and the second pole piece 12 are stacked or overlapped, the thermal barrier layer 18 is disposed on the buffer region 14, and the thermal barrier layer 18 is disposed on the surfaces of the first current collector 110 and the second current collector 120. The thermal barrier 18 may be a high polymer material with high toughness and high thermal conductivity, specifically, Polycarbonate (PC), polylactic acid (PLA), or a carbon fiber composite material, and the thermal barrier 18 may increase the strength and the thermal conductivity of the first current collector 110 and the second current collector 120, reduce the probability of short circuit, and alleviate the combustion failure caused by heat concentration.

As shown in fig. 8, in an embodiment, the first pole piece 11 is a cathode, the second pole piece 12 is an anode, and the first active layer 119 is disposed on the surface of the first current collector 110 in the buffer area 14. That is, although the buffer region 14 corresponding to the cathode is provided with the active layer, since the internal resistance of the cathode active layer is large, it can be seen from the formulas I ═ V/R and Q ═ I ═ RT that, when a short circuit occurs, the cathode active layer with large internal resistance can reduce the amount of heat generated in the case of the short circuit, and reduce the risk of combustion failure.

Second embodiment

Fig. 9 is a schematic perspective view of a battery according to a second embodiment of the present application. The battery 1 includes an electrode assembly 10, the electrode assembly 10 may be enclosed by a pouch 102, and the electrode assembly 10 is impregnated with an electrolyte.

Third embodiment

Fig. 10 is a schematic perspective exploded view of an electric device 100 according to a third embodiment of the present application. The present application further provides an electric device 100, which includes a body 101 and a battery 1 disposed in the body 101. In fig. 10, the electric device 100 is merely an example of a mobile phone, and in other embodiments, the electric device 100 may be a personal computer, an intelligent appliance, an industrial controller, an energy storage device, an electric tool, or the like.

Hereinbefore, specific embodiments of the present application are described with reference to the drawings. However, those skilled in the art will appreciate that various modifications and substitutions can be made to the specific embodiments of the present application without departing from the spirit and scope of the application. Such modifications and substitutions are intended to be within the scope of the present application.

Claims

1. An electrode assembly, comprising:

a first pole piece, the first pole piece comprising,

a first active layer disposed on the first current collector surface;

an opening region, wherein the opening region penetrates through the electrode assembly, the shape of the opening region is at least part of a circle, and the center of the opening region is the intersection point of the first intersection line and the second intersection line; and

2. The electrode assembly of claim 1, wherein the opening area has a radius R, the second region has a width La in the first intersecting line direction, and the third region has a width Lb in the second intersecting line direction.

3. The electrode assembly of claim 2, wherein the buffer region comprises a first buffer region corresponding to the first pole piece, at least a portion of the first buffer region overlapping the first intersection, the first buffer region comprising a first edge and a second edge, the first edge being proximal to the second region, the first edge having a set of sides of length [ La-2R, La ], the second edge being distal to the second region, the second edge having a set of sides of length [ La-R, La + R ].

4. The electrode assembly of claim 3, wherein the buffer region comprises a second buffer region corresponding to the first pole piece, at least a portion of the second buffer region overlapping the second intersection, the second buffer region comprising a third side proximate to the third region and having a set of sides [ Lb-2R, Lb ] that are distal from the third region and a fourth side having a set of sides [ Lb-R, Lb + R ].

5. The electrode assembly of claim 4, further comprising a second pole piece, the second pole piece comprising:

a second active layer disposed on the second current collector surface.

6. The electrode assembly of claim 5, wherein the buffer zones further comprise third and fourth buffer zones corresponding to the second pole piece, the third buffer zone at least partially overlapping the first buffer zone, the first buffer zone having a width of L1, the third buffer zone having a width of L2, L1-L2 [ -1mm, 1mm ], the fourth buffer zone at least partially overlapping the second buffer zone, the second buffer zone having a width of W1, the fourth buffer zone having a width of W2, W1-W2 [ -1mm, 1mm ].

7. The electrode assembly of claim 5, further comprising a connecting layer, wherein the first pole piece overlaps the second pole piece, wherein the connecting layer is disposed in the buffer region, and wherein the connecting layer is connected to the first current collector and the second current collector.

8. The electrode assembly of claim 5, further comprising a thermal barrier, wherein the first pole piece overlaps the second pole piece, wherein the thermal barrier is disposed in the buffer region, and wherein the thermal barrier is disposed on surfaces of the first current collector and the second current collector.

9. The electrode assembly of claim 5, wherein the first pole piece is a cathode and the second pole piece is an anode, and the second active layer is disposed on the surface of the second current collector in the buffer region.

10. A battery comprising an electrode assembly according to any one of claims 1 to 9.

11. An electric device comprising the battery of claim 10.