CN210576265U

CN210576265U - Electrode assembly and secondary battery

Info

Publication number: CN210576265U
Application number: CN201921599542.XU
Authority: CN
Inventors: 廖如虎; 曾钢; 虞永生; 戴亚
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2019-09-24
Filing date: 2019-09-24
Publication date: 2020-05-19
Anticipated expiration: 2029-09-24

Abstract

The utility model provides an electrode subassembly and secondary battery. The electrode assembly includes a plurality of first cells and a plurality of second cells, which are alternately arranged in a thickness direction. The first unit comprises a first pole piece, two second pole pieces, a first diaphragm and a second diaphragm; in the first cell, a first pole piece is secured between the first diaphragm and the second diaphragm, one second pole piece is secured to the first diaphragm, and the other second pole piece is secured to the second diaphragm. The second unit comprises a third pole piece, a third diaphragm and a fourth diaphragm; in the second cell, the third electrode is fixed between the third diaphragm and the fourth diaphragm in the thickness direction. The first pole piece and the third pole piece have the same polarity. The first separators of the plurality of first cells and the third separators of the plurality of second cells are integrally connected, and the second separators of the plurality of first cells and the fourth separators of the plurality of second cells are integrally connected.

Description

Electrode assembly and secondary battery

Technical Field

The utility model relates to a battery field especially relates to an electrode subassembly and secondary battery.

Background

Secondary batteries are increasingly widely used as representative energy storage devices in new energy fields, in the fields of mobile electronic devices, electric vehicles and the like. The electrode assembly is a core part of the secondary battery, and the current electrode assemblies are mainly classified into a winding type electrode assembly and a lamination type electrode assembly. The laminated electrode assembly is generally manufactured by sequentially stacking a plurality of positive electrode sheets and negative electrode sheets, but the positive and negative electrode sheets are easily displaced during the stacking process, resulting in misalignment of the positive and negative electrode sheets, which results in poor performance of the electrode assembly.

SUMMERY OF THE UTILITY MODEL

In view of the problems in the background art, an object of the present invention is to provide an electrode assembly and a secondary battery, which can simplify a molding process and improve production efficiency.

In order to accomplish the above object, the present invention provides an electrode assembly and a secondary battery.

The electrode assembly includes a first unit and a second unit, each of the first unit and the second unit being plural, and the plural first units and the plural second units being alternately arranged in a thickness direction. The first unit comprises a first pole piece, two second pole pieces, a first diaphragm and a second diaphragm; in the first unit, along the thickness direction, the first pole piece is fixed between the first diaphragm and the second diaphragm, one second pole piece is arranged on one side of the first diaphragm, which is far away from the first pole piece, and is fixed on the first diaphragm, and the other second pole piece is arranged on one side of the second diaphragm, which is far away from the first pole piece, and is fixed on the second diaphragm. The second unit comprises a third pole piece, a third diaphragm and a fourth diaphragm; in the second cell, the third electrode is fixed between the third diaphragm and the fourth diaphragm in the thickness direction. The first pole piece and the third pole piece have the same polarity. The first separators of the plurality of first cells and the third separators of the plurality of second cells are integrally connected, and the second separators of the plurality of first cells and the fourth separators of the plurality of second cells are integrally connected.

In some embodiments, both ends of the electrode assembly in the thickness direction are the second unit.

In some embodiments, the first and third pole pieces are negative pole pieces, and the second pole piece is a positive pole piece.

In some embodiments, the electrode assembly further includes a third unit located at an end of the electrode assembly in the thickness direction, the third unit being adjacent to the first unit. The third unit includes a fifth diaphragm and a sixth diaphragm, the fifth diaphragm of the third unit is integrally connected to the first diaphragm of the first unit, and the sixth diaphragm of the third unit is integrally connected to the second diaphragm of the first unit.

In some embodiments, the electrode assembly further includes a fourth cell located at an end of the electrode assembly in the thickness direction, the fourth cell being adjacent to the second cell. The fourth unit comprises a seventh diaphragm, an eighth diaphragm and a fourth pole piece, the seventh diaphragm and the eighth diaphragm are positioned on one side of the fourth pole piece far away from the second unit, and the seventh diaphragm, the eighth diaphragm and the fourth pole piece are fixedly connected. The seventh diaphragm of the fourth cell and the third diaphragm of the second cell are integrally connected, and the eighth diaphragm of the fourth cell and the fourth diaphragm of the second cell are integrally connected.

In some embodiments, the first and third pole pieces are positive pole pieces and the second and fourth pole pieces are negative pole pieces.

In some embodiments, in each of the first cells, the first separator is connected to the second separator, and a connection of the first separator and the second separator is located on an outer side of the first pole piece in the width direction. In each second cell, the third separator is connected to the fourth separator, and the connection of the third separator and the fourth separator is located on the outer side of the third pole piece in the width direction.

In some embodiments, the second pole piece of the first unit is also secured to the second unit.

In some embodiments, in the first unit, the first pole piece is fixed to the surface of the first diaphragm and the surface of the second diaphragm by electrophoresis, thermocompression, or adhesion, and the two second pole pieces are fixed to the surface of the first diaphragm and the surface of the second diaphragm, respectively, by electrophoresis, thermocompression, or adhesion. In the second unit, the third electrode is fixed to the surface of the third separator and the surface of the fourth separator by electrophoresis, thermocompression, or adhesion.

The secondary battery includes the electrode assembly.

The utility model has the advantages as follows: in the present application, a plurality of pole pieces may be first fixed to a separator and then folded to form an electrode assembly. The application separates the placing process and the folding process of the pole piece, can effectively save the time for placing the pole piece, fixes the pole piece on the diaphragm, can ensure the positioning precision of the pole piece, simplifies the forming process and improves the production efficiency.

Drawings

Fig. 1 is a schematic view of an electrode assembly according to a first embodiment of the present invention before molding.

Fig. 2 is a schematic view of the electrode assembly of fig. 1 after molding.

Fig. 3 is a schematic view of an electrode assembly according to a second embodiment of the present invention before forming.

Fig. 4 is a schematic view of the electrode assembly of fig. 3 after molding.

Fig. 5 is a schematic view of an electrode assembly according to a third embodiment of the present invention before molding.

Fig. 6 is a schematic view of the electrode assembly of fig. 5 after molding.

Fig. 7 is a schematic view of an electrode assembly according to a fourth embodiment of the present invention before molding.

Fig. 8 is a schematic view of the electrode assembly of fig. 7 after molding.

Fig. 9 is a schematic view of an electrode assembly according to a fifth embodiment of the present invention before molding.

Fig. 10 is a schematic view of the electrode assembly of fig. 9 after molding.

Wherein the reference numerals are as follows:

1 first unit

2 second unit

3 third unit

4 fourth unit

P1 first pole piece

P2 second pole piece

P3 third pole piece

P4 fourth pole piece

G1 first diaphragm

G2 second diaphragm

G3 third diaphragm

G4 fourth diaphragm

G5 fifth diaphragm

G6 sixth diaphragm

G7 seventh diaphragm

G8 eighth diaphragm

In the X width direction

Y thickness direction

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

In the description of the present application, unless explicitly stated or limited otherwise, the terms "first," "second," "third," "fourth," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance; the term "plurality" means more than two (including two); the term "coupled", unless otherwise specified or indicated, is to be construed broadly, e.g., "coupled" may be a fixed or removable connection or a connection that is either integral or electrical or signal; "connected" may be directly connected or indirectly connected through an intermediate. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

In the description of the present application, it should be understood that the terms "upper" and "lower" used in the description of the embodiments of the present application are used in a descriptive sense only and not for purposes of limitation. The present application is described in further detail below with reference to specific embodiments and with reference to the attached drawings.

The secondary battery comprises an electrode assembly which is a core component for realizing the charge and discharge functions of the secondary battery.

The secondary battery may be a pouch battery, and the electrode assembly is directly packaged in a packaging bag, which may be an aluminum plastic film.

The secondary battery of the present application may also be a hard-shell battery. The secondary battery further includes a case, a top cap plate, and an electrode terminal. The housing may have a hexahedral shape or other shapes. The case forms a receiving chamber therein to receive the electrode assembly and the electrolyte. The case forms an opening at one end, and the electrode assembly may be placed into the receiving cavity of the case through the opening. The housing may be made of a conductive metal material such as aluminum or aluminum alloy, or may be made of an insulating material such as plastic. The top cover plate is disposed on the case and covers the opening of the case, thereby enclosing the electrode assembly within the case. The electrode terminal is provided at the top cap plate, and the upper end of the electrode terminal protrudes to the upper side of the top cap plate and the lower end thereof may pass through the top cap plate, extend into the case, and be electrically connected to the electrode assembly.

The electrode assembly of the present application will be described in detail below in various embodiments.

Referring to fig. 1 and 2, in the first embodiment, the electrode assembly includes first and

second units

1 and 2, each of the first and

second units

1 and 2 is plural, and the plural first units 1 and the plural second units 2 are alternately arranged in the thickness direction Y.

The first cell 1 includes a first pole piece P1, two second pole pieces P2, a first diaphragm G1, and a second diaphragm G2. In the first unit 1, the first pole piece P1 is fixed between the first diaphragm G1 and the second diaphragm G2 in the thickness direction Y; the first pole piece P1 can be fixed on the surface of the first diaphragm G1 and the surface of the second diaphragm G2 by electrophoresis, heat pressing or adhesion. The polarity of the first pole piece P1 is opposite to that of the second pole piece P2.

In the first unit 1, in the thickness direction Y, one second pole piece P2 is disposed on the side of the first diaphragm G1 away from the first pole piece P1 and fixed to the first diaphragm G1, and the other second pole piece P2 is disposed on the side of the second diaphragm G2 away from the first pole piece P1 and fixed to the second diaphragm G2. The one second pole piece P2 is fixed to the surface of the first diaphragm G1 by electrophoresis, thermocompression or adhesion, and the other second pole piece P2 is fixed to the surface of the second diaphragm G2 by electrophoresis, thermocompression or adhesion.

The second unit 2 includes a third pole piece P3, a third diaphragm G3, and a fourth diaphragm G4. In the second unit 2, the third pole piece P3 is fixed between the third diaphragm G3 and the fourth diaphragm G4 in the thickness direction Y. The third pole piece P3 is fixed to the surface of the third diaphragm G3 and the surface of the fourth diaphragm G4 by electrophoresis, thermocompression, or adhesion. The first pole piece P1 and the third pole piece P3 have the same polarity, and the first pole piece P1 and the third pole piece P3 have the same structure.

The first diaphragm G1 of the first cells 1 and the third diaphragm G3 of the second cells 2 are integrally connected. Referring to fig. 2, all of the first diaphragms G1 and all of the third diaphragms G3 are formed by one diaphragm bent back and forth in a "Z" shape, the one diaphragm being bent in a multi-layered structure. The first diaphragm G1 of each first cell 1 is one layer of the multilayer structure, and the third diaphragm G3 of each second cell 2 is one layer of the multilayer structure.

The second diaphragms G2 of the first cells 1 and the fourth diaphragms G4 of the second cells 2 are integrally connected. All of the second diaphragms G2 and all of the fourth diaphragms G4 are formed by bending another diaphragm in a reciprocating manner in a "Z" shape, and the other diaphragm is bent in a multi-layered structure. The second diaphragm G2 of each first cell 1 is one layer of the multilayer structure, and the fourth diaphragm G4 of each second cell 2 is one layer of the multilayer structure.

Referring to fig. 1, the electrode assembly of the present embodiment may be formed according to the following steps:

(i) the method comprises the steps of alternately placing a plurality of first pole pieces P1 and a plurality of third pole pieces P3 on one membrane, then placing another membrane on the plurality of first pole pieces P1 and the plurality of third pole pieces P3 and covering the plurality of first pole pieces P1 and the plurality of third pole pieces P3, and finally fixing the plurality of first pole pieces P1 and the plurality of third pole pieces P3 between the two membranes in an electrophoresis, hot pressing or bonding mode.

(ii) And placing a plurality of second pole pieces P2 on the outer surfaces of the two diaphragms, and fixing the plurality of second pole pieces P2 to the two diaphragms by electrophoresis, hot pressing, bonding or the like. A plurality of second pole pieces P2 may be arranged in the manner shown in fig. 1.

(iii) Referring to fig. 2, folding is performed along the boundary of the first and third pole pieces P1 and P3, thereby forming the electrode assembly of the present embodiment.

In the known art, the membrane needs to be folded into multiple layers, one pole piece being placed on its surface each time it is folded; in the process of placing the pole pieces and the folded diaphragm, the pole pieces are easy to displace, so that the positive pole piece and the negative pole piece are staggered, and the performance of the electrode assembly is poor. If the pole pieces are repositioned, inefficient molding of the electrode assembly results.

In the present application, the plurality of pole pieces (the first pole piece P1, the second pole piece P2, and the third pole piece P3) may be fixed to two separators and then folded to form an electrode assembly. The application separates the placing process and the folding process of the pole piece, can effectively save the time for placing the pole piece, fixes the pole piece on the diaphragm, can ensure the positioning precision of the pole piece, simplifies the forming process and improves the production efficiency.

Preferably, the second pole piece P2 of the first unit 1 is also fixed to the second unit 2. After the step (iii), the folded electrode assembly can be hot-pressed, so that the two surfaces of each electrode piece are fixed on the diaphragm, the stability of the whole electrode assembly is improved, and the electrode assembly is prevented from scattering. Both the pole piece and the diaphragm are provided with a pvdf binder, and the pole piece and the diaphragm can be thermally combined together in a thermal compounding mode.

Both ends of the electrode assembly in the thickness direction Y are the second units 2. In the second cell 2, the third diaphragm G3 and the fourth diaphragm G4 may cover the third pole piece P3 from both sides, lowering the exposure of the third pole piece P3. The number of second cells 2 is one more than the number of first cells 1.

The positive pole piece comprises a positive current collector and a positive active substance layer coated on the surface of the positive current collector, the positive current collector can be an aluminum foil, and the positive active substance layer comprises a ternary material, lithium manganate or lithium iron phosphate. The negative pole piece comprises a negative current collector and a negative active substance layer coated on the surface of the negative current collector, the negative current collector can be a copper foil, and the negative active substance layer comprises graphite or silicon. In order to ensure that lithium ions can be embedded into the negative active material layer as much as possible and reduce the risk of lithium precipitation, the negative pole pieces are preferably arranged on the two sides of each positive pole piece in the thickness direction Y. In the present embodiment, the first pole piece P1 and the third pole piece P3 are negative pole pieces, and the second pole piece P2 is a positive pole piece, so that the risk of lithium precipitation can be reduced.

Other examples of the secondary battery of the present application are explained below. For the sake of simplifying the description, only the differences of the other embodiments from the first embodiment will be mainly described below, and the undescribed portions can be understood with reference to the first embodiment.

Referring to fig. 3 and 4, in the second embodiment, the electrode assembly further includes a third unit 3, the third unit 3 is located at an end of the electrode assembly in the thickness direction Y, and the third unit 3 is adjacent to the first unit 1.

The third unit 3 includes a fifth diaphragm G5 and a sixth diaphragm G6, the fifth diaphragm G5 of the third unit 3 is integrally connected to the first diaphragm G1 of the first unit 1, and the sixth diaphragm G6 of the third unit 3 is integrally connected to the second diaphragm G2 of the first unit 1.

In the present embodiment, if the third unit 3 is omitted, the second pole piece P2 of the first unit 1 is exposed, increasing the risk of short circuit of the secondary battery.

In this embodiment, the first pole piece P1 and the third pole piece P3 are positive pole pieces, and the second pole piece P2 is a negative pole piece, so as to ensure that the two sides of each positive pole piece along the thickness direction are both provided with negative pole pieces, thereby reducing the risk of lithium precipitation.

The third units 3 may be two and respectively located at both ends of the electrode assembly in the thickness direction Y. At this time, the number of the first cells 1 is one more than the number of the second cells 2.

Referring to fig. 5 and 6, in a third embodiment, the electrode assembly further includes a third unit 3 and

the fourth unit 4, the third unit 3, and the fourth unit 4 are respectively located at both ends of the electrode assembly in the thickness direction Y. The third cell 3 is adjacent to the first cell 1 and the fourth cell 4 is adjacent to the second cell 2.

The third unit 3 includes a fifth diaphragm G5 and a sixth diaphragm G6, the fifth diaphragm G5 of the third unit 3 is integrally connected to the first diaphragm G1 of the first unit 1, and the sixth diaphragm G6 of the third unit 3 is integrally connected to the second diaphragm G2 of the first unit 1. The third unit 3 can cover the second pole piece P2 of the first unit 1, so that the exposure of the second pole piece P2 is reduced, and the risk of short circuit is reduced.

The fourth unit 4 comprises a seventh diaphragm G7, an eighth diaphragm G8 and a fourth pole piece P4, the seventh diaphragm G7 and the eighth diaphragm G8 are located on the side of the fourth pole piece P4 remote from the second unit 2, and the seventh diaphragm G7, the eighth diaphragm G8 and the fourth pole piece P4 are fixedly connected. The seventh diaphragm G7, the eighth diaphragm G8 and the fourth plate P4 may be fixed together by electrophoresis, heat pressing or bonding.

The seventh diaphragm G7 of the fourth cell 4 and the third diaphragm G3 of the second cell 2 are integrally connected, and the eighth diaphragm G8 of the fourth cell 4 and the fourth diaphragm G4 of the second cell 2 are integrally connected.

In the present embodiment, the number of the first cells 1 and the second cells 2 is the same. The first pole piece P1 and the third pole piece P3 are positive pole pieces, and the second pole piece P2 and the fourth pole piece P4 are negative pole pieces. The fourth pole piece P4 of the fourth unit 4 can cooperate with the third pole piece P3 of the second unit 2 to reduce the risk of the third pole piece P3 of the second unit 2 from evolving lithium.

Referring to fig. 7 and 8, in the fourth embodiment, the number of the fourth cells 4 of the electrode assembly is two, and the two fourth cells 4 are respectively located at both ends of the electrode assembly in the thickness direction Y. Each fourth cell 4 is adjacent to the second cell 2.

In the present embodiment, the first pole piece P1 and the third pole piece P3 are positive pole pieces, and the second pole piece P2 and the fourth pole piece P4 are negative pole pieces. The number of second cells 2 is one more than the number of first cells 1. The fourth pole piece P4 of the fourth unit 4 can cooperate with the third pole piece P3 of the second unit 2 to reduce the risk of the third pole piece P3 of the second unit 2 from evolving lithium.

Referring to fig. 9 and 10, in the fifth embodiment, in each first cell 1, the first diaphragm G1 is connected to the second diaphragm G2, and the connection of the first diaphragm G1 and the second diaphragm G2 is located outside the first pole piece P1 in the width direction X. In each second cell 2, the third diaphragm G3 is connected to the fourth diaphragm G4, and the connection of the third diaphragm G3 and the fourth diaphragm G4 is located outside the third pole P3 in the width direction X.

Referring to fig. 9, the electrode assembly of the present embodiment may be formed in the following arrangement:

(ii) And performing hot pressing between the first pole piece P1 and the third pole piece P3 along the arrangement direction of the first pole pieces P1 and the third pole pieces P3 to connect the two diaphragms together.

(iii) And placing a plurality of second pole pieces P2 on the outer surfaces of the two diaphragms, and fixing the plurality of second pole pieces P2 to the two diaphragms by electrophoresis, hot pressing, bonding or the like. A plurality of second pole pieces P2 may be arranged as described in fig. 9.

(iv) Referring to fig. 10, folding is performed at the junction of two separators, thereby forming the electrode assembly of the present embodiment.

During the folding of the first embodiment, if the first pole piece P1 is subjected to excessive force, there may be a risk of separation from the first and second separators G1 and G2, resulting in misalignment of the first and second pole pieces P1 and P2, affecting the performance of the electrode assembly. In the present embodiment, since both sides of each first pole piece P1 in the width direction X are restricted by the separator, even if the first pole piece P1 is separated from the first separator G1 and the second separator G2, the position of the first pole piece P1 does not vary (or varies within an acceptably small range), and the performance of the electrode assembly is ensured.

Claims

1. An electrode assembly characterized by comprising a first unit (1) and a second unit (2), each of the first unit (1) and the second unit (2) being plural, and the plural first units (1) and the plural second units (2) being alternately arranged in a thickness direction (Y);

the first cell (1) comprises a first pole piece (P1), two second pole pieces (P2), a first diaphragm (G1) and a second diaphragm (G2); in the first unit (1), along the thickness direction (Y), a first pole piece (P1) is fixed between a first diaphragm (G1) and a second diaphragm (G2), one second pole piece (P2) is arranged on one side of the first diaphragm (G1) far away from the first pole piece (P1) and fixed to the first diaphragm (G1), and the other second pole piece (P2) is arranged on one side of the second diaphragm (G2) far away from the first pole piece (P1) and fixed to the second diaphragm (G2);

the second cell (2) comprises a third pole piece (P3), a third diaphragm (G3) and a fourth diaphragm (G4); in the second cell (2), a third pole piece (P3) is fixed between the third diaphragm (G3) and the fourth diaphragm (G4) in the thickness direction (Y); the first pole piece (P1) and the third pole piece (P3) have the same polarity;

the first diaphragm (G1) of the plurality of first cells (1) and the third diaphragm (G3) of the plurality of second cells (2) are integrally connected, and the second diaphragm (G2) of the plurality of first cells (1) and the fourth diaphragm (G4) of the plurality of second cells (2) are integrally connected.

2. The electrode assembly according to claim 1, wherein both ends of the electrode assembly in the thickness direction (Y) are the second cells (2).

3. The electrode assembly of claim 2, wherein the first and third pole pieces (P1, P3) are negative pole pieces and the second pole piece (P2) is a positive pole piece.

4. The electrode assembly of claim 1,

the electrode assembly further comprises a third unit (3), the third unit (3) is located at the end of the electrode assembly in the thickness direction (Y), and the third unit (3) is adjacent to the first unit (1);

the third unit (3) includes a fifth diaphragm (G5) and a sixth diaphragm (G6), the fifth diaphragm (G5) of the third unit (3) is integrated with the first diaphragm (G1) of the first unit (1), and the sixth diaphragm (G6) of the third unit (3) is integrated with the second diaphragm (G2) of the first unit (1).

5. The electrode assembly of claim 1 or 4,

the electrode assembly further comprises a fourth unit (4), the fourth unit (4) is located at the end of the electrode assembly in the thickness direction (Y), and the fourth unit (4) is adjacent to the second unit (2);

the fourth unit (4) comprises a seventh diaphragm (G7), an eighth diaphragm (G8) and a fourth pole piece (P4), the seventh diaphragm (G7) and the eighth diaphragm (G8) are positioned on one side of the fourth pole piece (P4) far away from the second unit (2), and the seventh diaphragm (G7), the eighth diaphragm (G8) and the fourth pole piece (P4) are fixedly connected;

the seventh diaphragm (G7) of the fourth cell (4) and the third diaphragm (G3) of the second cell (2) are integrally connected, and the eighth diaphragm (G8) of the fourth cell (4) and the fourth diaphragm (G4) of the second cell (2) are integrally connected.

6. The electrode assembly of claim 5, wherein the first (P1) and third (P3) pole pieces are positive pole pieces and the second (P2) and fourth (P4) pole pieces are negative pole pieces.

7. The electrode assembly of claim 1,

in each first cell (1), the first diaphragm (G1) is connected to the second diaphragm (G2), and the connection of the first diaphragm (G1) and the second diaphragm (G2) is located outside the first pole piece (P1) in the width direction (X);

in each second cell (2), the third diaphragm (G3) is connected to the fourth diaphragm (G4), and the connection of the third diaphragm (G3) and the fourth diaphragm (G4) is located outside the third pole piece (P3) in the width direction (X).

8. Electrode assembly according to claim 1, characterized in that the second pole piece (P2) of the first unit (1) is also fixed to the second unit (2).

9. The electrode assembly of claim 1,

in the first unit (1), a first pole piece (P1) is fixed on the surface of a first diaphragm (G1) and the surface of a second diaphragm (G2) through electrophoresis, hot pressing or bonding, and two second pole pieces (P2) are respectively fixed on the surface of the first diaphragm (G1) and the surface of a second diaphragm (G2) through electrophoresis, hot pressing or bonding;

in the second cell (2), the third pole piece (P3) is fixed to the surface of the third diaphragm (G3) and the surface of the fourth diaphragm (G4) by electrophoresis, thermocompression, or adhesion.

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