CN209401755U - Electrode assembly, secondary battery and battery module - Google Patents

Abstract

The utility model provides an electrode assembly, a secondary battery and a battery module. The battery module includes a plurality of secondary batteries arranged in sequence. The secondary battery includes a case, a cap assembly, and an electrode assembly. The housing has an accommodating chamber, a plurality of electrode assemblies are accommodated in the accommodating chamber, and the plurality of electrode assemblies are stacked and arranged along the axial direction of the accommodating chamber. The top cover assembly is connected to the casing and is located on one side of the plurality of electrode assemblies along the axial direction. The electrode assembly includes a first pole piece, a second pole piece, and a separator separating the first pole piece and the second pole piece. The first pole piece, the second pole piece and the separator are wound into a flat structure, and the flat structure includes a main body region and a corner region, and the corner regions are arranged at both ends of the main body region along the width direction. Both the first pole piece and the second pole piece are wound in multiple turns. In the main body region, the number of layers of the first pole piece is even, and the number of layers of the second pole piece is even. The first pole piece of the outermost ring has a first winding end, and the first winding end is disposed in the corner area.

Description

Electrode assembly, secondary battery and battery module

technical field

The utility model relates to the field of batteries, in particular to an electrode assembly, a secondary battery and a battery module.

Background technique

In order to increase the capacity, a plurality of electrode assemblies are usually provided inside the secondary battery, and each electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separator that are wound together. In the prior art, the flatness of the contact interface between two adjacent electrode assemblies is poor. Therefore, when the electrode assembly expands during the cycle, the expansion force on the contact interface is not uniform, resulting in the electrode assembly. The local deformation causes the pole piece to break, which affects the performance of the secondary battery.

Utility model content

In view of the problems existing in the background technology, the purpose of the present invention is to provide an electrode assembly, a secondary battery and a battery module, which can reduce the local deformation of the electrode assembly, avoid the breakage of the pole piece, and prolong the service life.

In order to achieve the above purpose, the present invention provides an electrode assembly, a secondary battery and a battery module.

The electrode assembly includes a first pole piece, a second pole piece, and a separator separating the first pole piece and the second pole piece. The first pole piece, the second pole piece and the diaphragm are wound into a flat structure, and the flat structure includes a main body region and a corner region, and the corner regions are arranged at both ends of the main body region along the width direction. Both the first pole piece and the second pole piece are wound in multiple turns. In the main body region, the number of layers of the first pole piece is even, and the number of layers of the second pole piece is even. The first pole piece of the outermost ring has a first winding end, and the first winding end is arranged in the corner area.

The first pole piece of the outermost ring has a first area and a second area, the first area corresponds to the position of the main body area, and the second area corresponds to the position of the corner area. The second area is bent and connected to the first area, and the central angle of the second area is 15°˜75° or 105°˜165°. One end of the second region away from the first region is the first winding end.

The first pole piece is a negative pole piece, and the active material of the first pole piece includes graphite, and the thickness of the first pole piece is 50 μm-200 μm.

A gap is provided between two adjacent first pole pieces, the gap includes a first gap corresponding to the position of the corner area, and the size of the first gap is 5 μm to 50 μm.

A gap is provided between two adjacent first pole pieces, and the gap includes a first gap and a second gap. The first gap corresponds to the position of the corner area, the second gap corresponds to the position of the main body area, and the size of the first gap is larger than that of the second gap.

In one embodiment, the second pole piece of the outermost ring has a second winding end, and the second winding end is disposed in the corner area. The second pole piece of the outermost ring has a third area and a fourth area, the third area corresponds to the position of the main body area, and the fourth area corresponds to the position of the corner area. The fourth area is curved and connected to the third area, and the central angle of the second area is larger than that of the fourth area. One end of the fourth region away from the third region is the second winding end.

In another embodiment, the second pole piece of the outermost ring has a second winding end, and the second winding end is located at the junction of the main body region and the corner region.

The secondary battery includes a case, a cap assembly, and the electrode assembly. The housing has an accommodating chamber, and the accommodating chamber has an opening; a plurality of electrode assemblies are accommodated in the accommodating chamber, and the plurality of electrode assemblies are stacked and arranged along the axial direction of the accommodating chamber. The top cover assembly is connected to the casing and is located on one side of the plurality of electrode assemblies along the axial direction.

The battery module includes the secondary batteries; the secondary batteries are multiple and arranged in sequence, and the arrangement direction of the multiple secondary batteries is perpendicular to the axial direction.

The beneficial effects of the present invention are as follows: In the present application, the first winding end is arranged in the corner area, and the corner areas of two adjacent electrode assemblies are not in contact. Therefore, the first winding end does not affect the two The contact interface of the main body region of the electrode assembly ensures the uniformity of the expansion force received by the contact interface, reduces the local deformation of the electrode assembly, and avoids the breakage of the pole piece. In the present application, by setting the number of layers of the first pole piece in the main body area to an even number and the number of layers of the second pole piece in the main body area to an even number, the symmetry of the main body area with respect to the winding center is improved, so that the winding center is along the axis The expansion force to both sides is equal, the uniformity of expansion of the main body area is improved, the local deformation of the electrode assembly is reduced, and the pole piece is prevented from breaking.

Description of drawings

FIG. 1 is an exploded view of a secondary battery according to the present invention.

2 is a cross-sectional view of a secondary battery according to the present invention.

3 is a schematic diagram of an embodiment of an electrode assembly according to the present invention.

FIG. 4 is a cross-sectional view of the electrode assembly of FIG. 3 .

FIG. 5 is an enlarged view of the block portion of FIG. 4 .

6 is a schematic diagram of another embodiment of an electrode assembly according to the present invention.

Among them, the reference numerals are described as follows:

1 Electrode assembly 2 Housing

11 The first pole piece 21 The accommodation chamber

111 First winding end 3 Top cover assembly

112 First area 31 Top cover

113 second area 32 electrode terminals

12 Second pole piece 33 Insulating member

121 Second winding end 34 Current collecting member

122 The third area G1 the first gap

123 Fourth area G2 second gap

13 Diaphragm X length direction

131 The third winding end Y width direction

14 Main body area Z axis

15 Corner District

Detailed ways

In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application will be described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application.

In the description of this application, unless otherwise expressly specified and limited, the terms "first", "second" and "third" are only used for the purpose of description, and cannot be construed as indicating or implying relative importance; the terms "Multiple" refers to two or more; unless otherwise specified or stated, the terms "connected", "fixed", etc. should be understood in a broad sense, for example, "connected" may be a fixed connection or a detachable connection Connection, or integral connection, or electrical connection, or signal connection; "connection" can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific situations.

In the description of this specification, it should be understood that the directional words such as "upper" and "lower" described in the embodiments of the present application are described from the perspective shown in the accompanying drawings, and should not be construed as referring to the embodiments of the present application. limited. The present application will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings.

In this application, a battery module generally includes a secondary battery, end plates, side plates, and bus bars. A plurality of secondary batteries are arranged in sequence. The secondary battery of the present application may be a prismatic lithium ion battery. The arrangement direction of the plurality of secondary batteries may be parallel to the width direction Y of each secondary battery. There are two end plates and are respectively arranged at both ends of the plurality of secondary batteries along the arrangement direction, two side plates are respectively arranged on both sides of the plurality of secondary batteries, and the end plates and the side plates are welded to each other. together and form a rectangular frame. The plurality of secondary batteries are fixed to the frame. The bus bar connects the plurality of secondary batteries together in series, parallel, or series-parallel.

1 and 2 , the secondary battery of the present application includes an electrode assembly 1 , a case 2 and a cap assembly 3 . The electrode assembly 1 may be plural.

An accommodating chamber 21 is formed inside the casing 2 to accommodate the plurality of electrode assemblies 1 and the electrolyte. One end of the casing 2 along the axial direction Z forms an opening, and the plurality of electrode assemblies 1 can be placed into the casing 2 through the opening, wherein the axial direction Z is parallel to the extending direction of the accommodating chamber 21 . The casing 2 can be made of conductive metal material such as aluminum or aluminum alloy. The battery module of the present application can be used in electric vehicles. When the top cover assembly 3 of the secondary battery on the electric vehicle is substantially parallel to the ground, the axial direction Z of the accommodating chamber 21 is parallel to the height direction of the secondary battery and perpendicular to the two The width direction Y of the secondary battery, the longitudinal direction X, and the arrangement direction of the plurality of secondary batteries.

The plurality of electrode assemblies 1 are arranged in layers along the axial direction Z of the accommodating chamber 21 . 3 and 4 , each electrode assembly 1 includes a first pole piece 11 , a second pole piece 12 and a separator 13 , and the separator 13 separates the first pole piece 11 and the second pole piece 12 .

The top cover assembly 3 includes a top cover plate 31 , an electrode terminal 32 , an insulating member 33 and a current collecting member 34 . The top cover plate 31 is connected to the casing 2 and covers the opening of the casing 2 , thereby enclosing the electrode assembly 1 in the accommodating chamber 21 of the casing 2 . The insulating member 33 is provided on the inner side of the top cover plate 31 to separate the top cover plate 31 from the electrode assembly 1 . The electrode terminals 32 are provided on the top cover plate 31 and protrude to the outside of the top cover plate 31 . There are two electrode terminals 32 and two current collecting members 34 , one current collecting member 34 connects the first pole piece 11 and one electrode terminal 32 , and the other current collecting member 34 connects the second pole piece 12 and the other electrode terminal 32 .

During the charging and discharging process, the first pole piece 11 and the second pole piece 12 of each electrode assembly 1 will expand. In the present application, the plurality of electrode assemblies 1 in the secondary battery are arranged along the axial direction Z, and thus the expansions of the plurality of electrode assemblies 1 are superimposed in the axial direction Z. In the width direction Y, the expansion of the plurality of electrode assemblies 1 will not be superimposed, so the expansion force of the electrode assemblies 1 acting on the casing 2 is also small.

In the battery module, the arrangement direction of the plurality of secondary batteries is perpendicular to the axial direction Z. Therefore, even if the expansion amounts of all the electrode assemblies 1 in the arrangement direction are superimposed together, an excessive resultant force will not be generated. , so as to prevent the secondary battery from being crushed and ensure the performance and life of the secondary battery.

In addition, in the known technology, the two end plates of the battery module need to clamp the plurality of secondary batteries, and if the resultant force generated by the expansion of the secondary batteries is too large, the welding of the end plates and the side plates may be broken. , causing the battery module to fail. In the present application, the resultant force generated by the plurality of secondary batteries during expansion is small, so as to avoid failure of the battery module.

The first pole piece 11 , the second pole piece 12 and the diaphragm 13 are wound into a flat structure, and the first pole piece 11 , the second pole piece 12 and the diaphragm 13 are all wound in multiple turns. When forming, the head end of the first pole piece 11, the head end of the second pole piece 12 and the head end of the diaphragm 13 can be fixed to the winding shaft, and the winding shaft spirally winds the first pole piece 11 by rotating. , the second pole piece 12 and the diaphragm 13, and form a winding body; after the winding is formed, the winding shaft is pulled out from the winding body; finally, the winding body is pressed into a flat shape. It is added here that the position of the winding shaft is the winding center C of the flat structure.

The flat structure includes a main body region 14 and a corner region 15 , and the corner regions 15 are disposed at both ends of the main body region 14 along the width direction Y. As shown in FIG. In the secondary battery, a plurality of electrode assemblies 1 are directly stacked in the axial direction Z, and the body regions 14 of two adjacent electrode assemblies 1 are in contact with each other.

The first pole piece 11 of the outermost ring has a first winding end 111 , and the first winding end 111 is a free end of the first pole piece 11 away from the winding center C. In the prior art, the first winding end 111 is disposed in the main body region 14 , resulting in poor flatness of the outer surface of the main body region 14 . When the electrode assembly 1 expands, the contact interface of the main body regions 14 of the two electrode assemblies 1 (especially the position where the first winding end 111 is located) is subjected to uneven expansion force, resulting in severe local deformation of the electrode assembly 1, resulting in extreme Pieces break.

Therefore, in the present application, the first winding end 111 is preferably arranged in the corner area 15 . The corner regions 15 of the two adjacent electrode assemblies 1 are not in contact. Therefore, the first winding end 111 does not affect the contact interface of the main body regions 14 of the two electrode assemblies 1, thereby ensuring that the contact interface receives The uniformity of the expansion force reduces the local deformation of the electrode assembly 1 and avoids the breakage of the pole pieces.

In the main body region 14, the first pole piece 11 and the second pole piece 12 are divided into multiple layers along the axial direction Z. As shown in FIG. Before the electrode assembly 1 is expanded, each layer of the first pole pieces 11 in the main body region 14 is substantially perpendicular to the axial direction Z, and each layer of the second pole pieces 12 in the main body region 14 is substantially perpendicular to the axial direction Z.

Preferably, in the main body region 14, the number of layers of the first pole pieces 11 is an even number, and the number of layers of the second pole pieces 12 is an even number. That is to say, the first pole pieces 11 located on both sides of the winding center C along the axial direction Z have the same number of layers, and the second pole pieces 12 located on both sides of the winding center C along the axial direction Z have the same number of layers. Numbers are the same.

In the present application, by setting the number of layers of the first pole pieces 11 in the main body region 14 to an even number and the number of layers of the second pole pieces 12 of the main body region 14 to an even number, the symmetry of the main body region 14 about the winding center C is improved, The expansion force on both sides of the winding center C along the axial direction Z is equalized, the uniformity of expansion of the main body region 14 is improved, the local deformation of the electrode assembly 1 is reduced, and the pole piece is prevented from breaking.

4 and 5 , the first pole piece 11 of the outermost ring has a first area 112 and a second area 113 . The first region 112 corresponds to the position of the main body region 14 , in other words, the first region 112 is a layer of the first pole piece 11 of the main body region 14 . In the width direction Y, the width of the first region 112 is equal to the width of the main body region 14 . The overall flatness of the first region 112 is good, which can ensure the flatness of the outer surface of the main body region 14 .

The second area 113 corresponds to the position of the corner area 15 . Specifically, the second area 113 extends from one end of the first area 112 and is bent into an arc shape, wherein the end of the second area 113 away from the first area 112 is the first winding end 111 . Before the electrode assembly 1 is expanded, ignoring the thickness of the first pole piece 11 , the second area 113 is approximately a circular arc surface, the first area 112 is approximately a plane, and the first area 112 is substantially tangent to the second area 113 .

When the first pole piece 11 is expanded and deformed, the first winding end 111 may move under the action of the expansion force. If α is less than 15°, the arc length of the second region 113 is too small, and the first winding end 111 may move to the main body region 14 under the action of the expansion force, thereby affecting the contact interface between the two main body regions 14 , resulting in The electrode assembly 1 is locally deformed seriously, causing the pole piece to break. If α is between 75° and 105°, when the electrode assembly 1 expands, the first winding end 111 may squeeze the casing 2, resulting in stress concentration on the first winding end 111, which is likely to cause severe local deformation of the pole piece , even broken. If α is greater than 165°, when the electrode assembly 1 expands to a large degree, the first winding end 111 may also come into contact with the adjacent electrode assembly. Therefore, preferably, the central angle α of the second region 113 is 15°˜75° or 105°˜165°.

The first pole piece 11 can be a negative pole piece. The first pole piece 11 includes copper foil and a negative electrode active material coated on the surface of the copper foil, and the negative electrode active material includes graphite or silicon. Correspondingly, the second pole piece 12 is a positive pole piece, and the second pole piece 12 includes an aluminum foil and a positive electrode active material coated on the surface of the aluminum foil, and the positive electrode active material includes lithium manganate or lithium iron phosphate.

The thickness of the first pole piece 11 is 50 μm-200 μm. Since the first pole piece 11 has a relatively large thickness, if the first winding end 111 is disposed in the main body region 14 , the flatness of the outer surface of the main body region 14 will be seriously affected.

The second pole piece 12 of the outermost ring has a second winding end 121 , and the second winding end 121 is the free end of the second pole piece 12 away from the winding center C. In the present application, the second winding end 121 is preferably arranged in the corner region 15 . The second winding end 121 will not affect the contact interface of the main body regions 14 of the two electrode assemblies 1, thereby ensuring the uniformity of the expansion force on the contact interface, reducing local deformation of the electrode assembly 1, and avoiding pole piece breakage.

The second pole piece 12 of the outermost ring has a third area 122 and a fourth area 123 . The third region 122 corresponds to the position of the main body region 14 , in other words, the third region 122 is a layer of the second pole piece 12 of the main body region 14 . In the width direction Y, the width of the third region 122 is equal to the width of the main body region 14 . The overall flatness of the third region 122 is good, which can ensure the flatness of the outer surface of the main body region 14 .

The fourth area 123 corresponds to the position of the corner area 15 . Specifically, the fourth area 123 extends from one end of the third area 122 and is bent into an arc shape, wherein the end of the fourth area 123 away from the third area 122 is the second winding end 121 . Before the electrode assembly 1 is expanded, ignoring the thickness of the second pole piece 12 , the fourth area 123 is approximately an arc surface, the third area 122 is approximately a plane, and the third area 122 is substantially tangent to the fourth area 12 .

The fourth area 123 is located inside the second area 113 . Since the second pole piece 12 is a positive pole piece, the lithium ions in the fourth region 123 need to be embedded in the second region 113. If the second region 113 cannot completely cover the fourth region 123, the lithium ions cannot be completely embedded in the second region 113. region 113, resulting in lithium precipitation. Therefore, in order to avoid lithium precipitation, the central angle of the second region 113 should be larger than that of the fourth region 123 , so that the second region 113 completely covers the fourth region 123 .

The diaphragm 13 needs to completely separate the first pole piece 11 and the second pole piece 12 to avoid a short circuit, therefore, the third winding end 131 of the diaphragm 13 usually needs to extend beyond the first winding end 111 and the second winding end 121 . Typically, the third wrap end 131 is provided in the body region 14 . The two electrode assemblies 1 can clamp the third winding end 131, thereby preventing the separator 13 from unraveling. Since the thickness of the separator 13 is relatively small (generally 10 μm-20 μm), the third winding end 131 has little influence on the flatness of the main body region 14 and will not cause the pole piece to break.

A gap is provided between two adjacent circles of the first pole pieces 11 , and the gap includes a first gap G1 corresponding to the position of the corner region 15 . When the first pole piece 11 and the second pole piece 12 are expanded, the stress concentration in the corner region 15 is serious, which easily causes the pole pieces to break. By setting the first gap G1 , the expansion space can be increased for the first pole piece 11 and the second pole piece 12 , thereby releasing the expansion stress and reducing the risk of pole piece breakage.

The size of the first gap G1 is 5 μm to 50 μm. Specifically, referring to FIG. 5 , in the corner region 15 , the distance between the first pole pieces 11 of two adjacent layers is d1 , and two layers of diaphragms 13 and one layer of second pole pieces 11 are arranged between the two layers of first pole pieces 11 . The pole piece 12, therefore, the value of d1 minus the thickness of the two layers of diaphragms 13 and the thickness of one layer of the second pole piece 12 is the size of the first gap G1. If the size of the first gap G1 is less than 5 μm, the expansion space reserved in the present application is limited, and the expansion stress of the corner region 15 cannot be fully released, and there is still a risk of pole piece fracture. However, if the size of the first gap G1 is larger than 50 μm, space will be wasted and the energy density of the secondary battery will be affected.

The gap between the two adjacent first pole pieces 11 further includes a second gap G2 , and the second gap G2 corresponds to the position of the main body region 14 . Similarly, in the main body area 14, the distance between the first pole pieces 11 of two adjacent layers is d2, and the value of d2 minus the thickness of the two layers of diaphragms 13 and the thickness of the second pole piece 12 is the second pole piece 12. The size of the gap G2. The second gap G2 may increase the expansion space for the first pole piece 11 and the second pole piece 12 of the main body region 14 , thereby releasing the expansion stress.

When the electrode assembly 1 expands, the stress in the corner region 15 is the most concentrated and the deformation is most likely to occur. Under the action of stress, the first gap G1 will be severely reduced. At the same time, since the first pole piece 11 and the second pole piece 12 of the corner region 15 are arc-shaped, it is easier to deform under the action of stress. When the stress is too large, the first pole piece 11 and the second pole piece 12 in the corner region 15 are prone to break.

Since the stress in the corner region 15 is more concentrated, if the size of the first gap G1 is equal to the size of the second gap G2 before expansion, then when the electrode assembly 1 is expanded and deformed, the first gap G1 will shrink more than the second gap G1 The degree to which the gap G2 is reduced. That is, when the secondary battery is cycled to a certain extent, the size of the first gap G1 may be smaller than the size of the second gap G2. At this time, the electrolyte in the main body region 14 is larger than that in the corner region 15 , resulting in a difference in wettability between the main body region 14 and the corner region 15 , which affects the consistency of the dynamic performance of the electrode assembly 1 .

Therefore, in the present application, the size of the first gap G1 is preferably larger than that of the second gap G2, so that the volume of the electrolyte in the first gap G1 is larger than the volume of the electrolyte in the second gap G2 before expansion. In the present application, by increasing the first gap G1, the stress of the corner region 15 is released in time, and the first pole piece 11 and the second pole piece 12 in the corner region 15 are prevented from breaking. Comparatively, the size of the second gap G2 is small, and has little influence on the thickness of the secondary battery along the width direction Y. Since the corner region 15 is subjected to greater stress, when the secondary battery is cycled to a certain extent, the size of the first gap G1 will be approximately equal to the size of the second gap G2, so that the expanded first gap G1 will have a larger size. The volume of the electrolyte is substantially equal to the volume of the electrolyte in the second gap G2 , thereby improving the wettability difference between the main body region 14 and the corner region 15 to a certain extent and ensuring the consistency of the dynamic performance of the electrode assembly 1 .

In addition, when the body region 14 is expanded to a certain extent, the body region 14 will contact the insulating member 33 , and the top cover plate 31 and the insulating member 33 will limit the deformation of the body region 14 . However, the corner area 15 is arc-shaped, the casing 2 cannot limit the twisting deformation of the corner area 15, and the first gap G needs to have a larger size.

Next, a second embodiment of the secondary battery of the present application will be described. In order to simplify the description, only the differences between the second embodiment and the first embodiment are mainly introduced below, and the undescribed parts can be understood with reference to the first embodiment.

6 , compared with the first embodiment, in the second embodiment, the fourth region 123 may be omitted, and the second winding end 121 is located at the junction of the main body region 14 and the corner region 15 . When the second winding tip 121 is located at the junction of the main body region 14 and the corner region 15, the second winding tip 121 will not affect the flatness of the outer surface of the main body region 14, thereby reducing the local deformation of the electrode assembly 1 and avoiding the pole piece fracture.

Claims (10)

1. a kind of electrode assembly (1), which is characterized in that including the first pole piece (11), the second pole piece (12) and diaphragm (13), diaphragm (13) the first pole piece (11) and the second pole piece (12) are separated；

First pole piece (11), the second pole piece (12) and diaphragm (13) are wound as flat structure, and the flat structure includes Body region (14) and corner regions (15), corner regions (15) are set to the both ends of body region (14) (Y) in the width direction；

First pole piece (11) and the second pole piece (12) are wound as multi-turn；

In body region (14), the number of plies of the first pole piece (11) is even number, and the number of plies of the second pole piece (12) is even number；

The first pole piece (11) of outmost turns has the first winding end (111), and the first winding end (111) is set to corner regions (15)。

2. electrode assembly (1) according to claim 1, which is characterized in that

The first pole piece (11) of outmost turns has first area (112) and second area (113), first area (112) and main body Area (14) position is corresponding, and second area (113) is corresponding with corner regions (15) position；

Second area (113) bending be arranged simultaneously connect with first area (112), and second area (113) central angle for 15 °~ 75 ° or 105 °~165 °；

One end of the separate first area (112) of second area (113) is the first winding end (111).

3. electrode assembly (1) according to claim 1, which is characterized in that

First pole piece (11) is cathode pole piece, and the active material of the first pole piece (11) includes graphite；

First pole piece (11) with a thickness of 50 μm -200 μm.

4. electrode assembly (1) according to claim 1, which is characterized in that

It is equipped with gap between two adjacent circles the first pole piece (11), the gap includes corresponding with corner regions (15) position first Gap (G1), the size of the first gap (G1) are 5 μm to 50 μm.

5. electrode assembly (1) according to claim 1, which is characterized in that

Gap is equipped between two adjacent circles the first pole piece (11), the gap includes the first gap (G1) and the second gap (G2)；

(G1) is corresponding with corner regions (15) position in the first gap, and the second gap (G2) is corresponding with body region (14) position, between first The size of gap (G1) is greater than the size of the second gap (G2).

6. electrode assembly (1) according to any one of claims 1-5, which is characterized in that the second pole piece of outmost turns (12) there are the second winding end (121), and the second winding end (121) is set to corner regions (15).

7. electrode assembly (1) according to claim 6, which is characterized in that

The second pole piece (12) of outmost turns has third region (122) and the fourth region (123), third region (122) and main body Area (14) position is corresponding, and the fourth region (123) is corresponding with the position of corner regions (15)；

The fourth region (123) bending is arranged and connect with third region (122), and second area (113) central angle is greater than the 4th The central angle in region (123)；

One end of the separate third region (122) of the fourth region (123) is the second winding end (121).

8. electrode assembly (1) according to any one of claims 1-5, which is characterized in that the second pole piece of outmost turns (12) there are the second winding end (121), and the second winding end (121) is located at the boundary of body region (14) and corner regions (15) Place.

9. a kind of secondary cell, which is characterized in that including any one of shell (2), cap assembly (3) and claim 1-8 The electrode assembly (1)；

Shell (2) has accommodating chamber (21), and accommodating chamber (21) has opening；

Multiple electrodes component (1) is contained in accommodating chamber (21), and multiple electrodes component (1) is along the axial direction of accommodating chamber (21) (Z) it is stacked；

Cap assembly (3) is connected to shell (2) and is located at multiple electrodes component (1) along the side of axial direction (Z).

10. a kind of battery modules, which is characterized in that including secondary cell as claimed in claim 9；Secondary cell be it is multiple and according to Secondary arrangement, the orientation of the multiple secondary cell is perpendicular to axial direction (Z).