阅读说明：本技术 电极组件和电池 (Electrode assembly and battery ) 是由 王攀 刘慧君 张远兵 石长川 于 2020-05-20 设计创作，主要内容包括：本申请提供一种电极组件,由第一极片、隔离膜和第二极片卷绕形成。第一极片的卷绕终止端位于第二极片的卷绕终止端的远离卷心的外侧。第一极片的卷绕终止端上的第一活性物质层覆盖第一集流体朝向第二极片的一侧表面,所述第一极片的卷绕终止端上的所述第一集流体背离所述第二极片的一侧表面未涂覆所述第一活性物质层。上述电极组件的最外圈的极片没有空铝箔的设计,提高锂离子电池的能量密度的同时,也提高了跌落安全性能。本申请还提供一种具有上述电极组件的电池。(The application provides an electrode assembly, which is formed by winding a first pole piece, a separation film and a second pole piece. The winding end of the first pole piece is positioned on the outer side, far away from the winding core, of the winding end of the second pole piece. The coiling of first pole piece terminates and covers a side surface of first mass flow body orientation second pole piece in the first active material layer on the end, the coiling of first pole piece terminates and is served first mass flow body deviates from a side surface uncoated of second pole piece first active material layer. The outermost pole piece of the electrode assembly is not provided with the hollow aluminum foil, so that the energy density of the lithium ion battery is improved, and meanwhile, the falling safety performance is also improved. The present application also provides a battery having the above electrode assembly.)

1. An electrode assembly, comprising:

a first pole piece;

a second pole piece having a polarity opposite to that of the first pole piece; and

a separator disposed between the first and second pole pieces, the electrode assembly being formed by winding the first pole piece, the separator, and the second pole piece;

the winding end of the first pole piece is positioned on the outer side, far away from the winding center, of the winding end of the second pole piece;

the first active material layer on the winding termination end of the first pole piece covers one side surface of the first current collector facing the second pole piece; electrode subassembly still includes the bonding piece, the thickness of bonding piece is 15um ~ 25um, the bonding piece is connected the winding of first pole piece terminates the end and covers electrode subassembly's partial surface is in order to fix the winding of first pole piece terminates the end.

2. The electrode assembly of claim 1, wherein the adhesive member is a hot melt adhesive adhered to the winding end of the first pole piece and the outer surface of the electrode assembly.

3. The electrode assembly of claim 2, wherein the adhesive has a hot melt temperature of 120 ℃ or less and a hot melt pressure of 3MPa or less.

4. The electrode assembly of claim 1, wherein the winding end of the second pole piece extends beyond the winding end of the first pole piece in the winding direction by a length greater than or equal to 2 mm.

5. The electrode assembly of claim 4, wherein the winding end of the separator protrudes in the winding direction beyond the winding end of the second pole piece and is attached to the inner surface of the adhesive.

6. The electrode assembly of claim 1, further comprising a first tab and a second tab, the first tab connecting the first pole piece and the second tab connecting the second pole piece.

7. The electrode assembly of claim 6, wherein a winding start end of the first pole piece is provided with a first empty foil area, a winding start end of the second pole piece is provided with a second empty foil area, the first tab is disposed in the first empty foil area, and the second tab is disposed in the second empty foil area.

8. The electrode assembly of claim 7, wherein the electrode assembly includes a first insulator disposed in the first empty foil zone and covering the first tab.

9. The electrode assembly of claim 7, wherein the second empty foil section extends beyond the first empty foil section, the electrode assembly further comprising a second insulating member covering an end of the first empty foil section.

10. A battery comprising an electrode assembly according to any one of claims 1 to 9 and a package in which the electrode assembly is housed, wherein a tab of the electrode assembly protrudes from the package.

Technical Field

The present invention relates to the field of batteries, and more particularly, to an electrode assembly and a battery having the same.

Background

When a general winding type battery is in a tail ending process, the tail part of a pole piece on the outer layer of the battery core is provided with a part of empty aluminum foil (both surfaces of the pole piece are not provided with active substance coatings), and the edge of the empty aluminum foil at the tail part and the coating edge at the tail part of the empty aluminum foil are generally attached with a layer of insulating tape for protecting the short circuit risk caused by lithium dendrites at the edge of the pole piece coating. The empty aluminum foil at the tail part and the insulating adhesive tape at the edge of the tail part coating occupy a certain volume of the battery cell, so that the energy density of the battery cell is reduced. In addition, the electric core generally uses an aluminum plastic film to carry out sealed package, a gap exists between the electric core and the shell of the sealed package electric core, the electric core is subjected to falling impact, the hollow aluminum foil of the electric core self and the outer tail part is easy to break, and fragments formed by crushing are contacted with the broken pole pieces of the electric core under the constraint of the package of the shell, so that the short circuit generates heat and even the events such as fire explosion occur.

Disclosure of Invention

In view of the above, it is necessary to provide an electrode assembly having a cell outer layer without an empty aluminum foil and capable of improving energy density, and a battery having the same.

An embodiment of the present application provides an electrode assembly, including first pole piece, second pole piece and barrier film, the polarity of second pole piece with the polarity of first pole piece is opposite, the barrier film set up in first pole piece with between the second pole piece, electrode assembly by first pole piece the barrier film with the second pole piece is convoluteed and is formed. The first pole piece comprises a first current collector and a first active substance layer, the first active substance layer is arranged on the surface of the first current collector, and the winding termination end of the first pole piece is located on the outer side, far away from the winding core, of the winding termination end of the second pole piece. The first active material layer on the winding termination end of the first pole piece covers one side surface of the first current collector facing the second pole piece. Electrode subassembly still includes the bonding piece, the thickness of bonding piece is 15um ~ 25um, the bonding piece is connected the winding of first pole piece terminates the end and covers electrode subassembly's partial surface.

In an optional embodiment, a side surface of the first current collector on the winding terminating end of the first pole piece, which faces away from the second pole piece, is not coated with the first active material layer.

In an alternative embodiment, the adhesive member is a hot melt adhesive and is adhered to the outer surface of the electrode assembly.

Furthermore, the hot melting temperature of the bonding piece is less than or equal to 120 ℃, and the hot melting pressure is less than or equal to 3 MPa.

In an alternative embodiment, the winding end of the second pole piece extends out of the winding end of the first pole piece along the winding direction, and the extending length is greater than or equal to 2 mm.

Furthermore, the winding end of the isolation film extends out of the winding end of the second pole piece along the winding direction and is attached to the inner surface of the adhesive piece.

In an optional embodiment, the electrode assembly further includes a first tab and a second tab, the first tab is connected to the first pole piece, the second tab is connected to the second pole piece, and projections of the first tab and the second tab do not overlap in a thickness direction of the electrode assembly.

Furthermore, a first empty foil area is arranged at the winding starting end of the first pole piece, a second empty foil area is arranged at the winding starting end of the second pole piece, the first tab is arranged in the first empty foil area, and the second tab is arranged in the second empty foil area.

Further, the electrode assembly includes a first insulator disposed at the first empty foil region and covering the first tab.

In an alternative embodiment, the second empty foil section extends beyond the first empty foil section, and the electrode assembly further includes a second insulating member covering an end of the first empty foil section.

Embodiments of the present application further provide a battery including an electrode assembly and a package, the electrode assembly being any one of the electrode assemblies described above, the electrode assembly being housed in the package, and tabs of the electrode assembly protruding out of the package.

The outermost pole piece of the electrode assembly is not provided with a hollow aluminum foil, so that the energy density of the lithium ion battery is improved, the safety performance of the lithium ion battery in use scenes such as falling is improved, and the aluminum foil consumption of a single motor assembly is reduced.

Drawings

Fig. 1 is a schematic view of a winding structure of an electrode assembly in one embodiment.

Fig. 2 is a schematic view of a winding structure of the electrode assembly in one embodiment.

FIG. 3 is a schematic view of an electrode assembly in one embodiment.

Fig. 4 is a schematic view of an expanded structure of the first pole piece in a comparative example.

Fig. 5 is a schematic view of an expanded structure of the first pole piece in an embodiment.

Fig. 6 is a schematic view of an expanded structure of the first pole piece in a comparative example.

Fig. 7 is a schematic view of an expanded structure of the first pole piece in an embodiment.

Fig. 8 is a schematic view of a winding structure of the electrode assembly in a comparative example.

Fig. 9 is a schematic structural diagram of a battery in one embodiment.

Description of the main element symbols:

electrode assembly 100

First plane 101

Second plane 102

First arc surface 103

Second cambered surface 104

Empty aluminum foil 105

Insulating tape 106

First pole piece 10

First current collector 11

First active material layer 12

Winding end 13

First empty foil region 14

Second pole piece 20

Second current collector 21

Second active material layer 22

Second empty foil area 23

Isolation diaphragm 30

Winding end 31

Adhesive member 40

First tab 50

Second pole ear 60

First insulator 70

Second insulator 80

Battery 200

Package 201

The specific implementation mode is as follows:

the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. When an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only.

Unless defined otherwise, all 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. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "or/and" includes any and all combinations of one or more of the associated listed items.

An embodiment of the present application provides an electrode assembly, including first pole piece, second pole piece and barrier film, the polarity of second pole piece with the polarity of first pole piece is opposite, the barrier film set up in first pole piece with between the second pole piece, electrode assembly by first pole piece the barrier film with the second pole piece is convoluteed and is formed. The first pole piece comprises a first current collector and a first active substance layer, the first active substance layer is arranged on the surface of the first current collector, and the winding termination end of the first pole piece is located on the outer side, far away from the winding core, of the winding termination end of the second pole piece. The first active material layer on the winding termination end of the first pole piece covers one side surface of the first current collector facing the second pole piece. Electrode subassembly still includes the bonding piece, the thickness of bonding piece is 15um ~ 25um, the bonding piece is connected the winding of first pole piece terminates the end and covers electrode subassembly's partial surface.

The outer ring of the electrode assembly is not provided with a hollow aluminum foil, and is combined with an ultrathin bonding piece with the thickness of 15 um-25 um, so that the energy density of the lithium ion battery is improved, the safety performance of the lithium ion battery in use scenes such as falling is improved, and the aluminum foil consumption of a single motor assembly is reduced.

Some embodiments of the present application are described in detail. In the following embodiments, features of the embodiments may be combined with each other without conflict.

Referring to fig. 1, in an embodiment of the present application, an electrode assembly 100 includes a first pole piece 10, a second pole piece 20, and a separator 30. The polarities of the first pole piece 10 and the second pole piece 20 are opposite, the separator 30 is disposed between the first pole piece 10 and the second pole piece 20, the electrode assembly 100 is formed by winding the first pole piece 10, the separator 30 and the second pole piece 20 around a winding needle, and the winding needle is taken out of the electrode assembly 100 after the winding process is completed. The electrode assembly 100 includes a winding end including the winding end 13 of the first pole piece 10, the winding end of the second pole piece 20, and the winding end of the separator 30. The winding termination end 31 of the separator 30 is located between the winding termination ends including the winding termination end 13 of the first pole piece 10 and the winding termination end of the second pole piece 20. The winding end 13 of the first pole piece 10 is located at the outermost layer of the electrode assembly 100.

First pole piece 10 includes first mass flow body 11 and first active material layer 12, first active material layer 12 set up in first mass flow body 11 surface, the winding of first pole piece 10 ends the end and is located the outside of keeping away from the book heart of the winding of second pole piece 20 ends the end.

In the embodiment of the present application, the first electrode sheet 10 is a cathode sheet, the first current collector 11 can be an aluminum foil layer, the first active material layer 12 can be a cathode active material layer, and can be LiCo0₂、LiFeP0₄And the like can deintercalate lithium ions. The second electrode sheet 20 is an anode sheet and comprises a second current collector 21 and a second active material layer 22, the second current collector can be selected as a copper foil layer, and the second active material layer 22 can be selected as graphite, soft carbon, hard carbon and Li₄Ti₅0₁₂And the like, which can intercalate lithium ions.

The winding of first pole piece 10 ends end 13 and is the outermost pole piece's of electrode subassembly 100 structure, first active substance layer 12 covers on the winding of first pole piece 10 ends end 13 first mass flow body 11 orientation a side surface of second pole piece 20, on the winding of first pole piece 10 ends end 13 first mass flow body 11 deviates from a side surface of second pole piece 20 is not coated first active substance layer 12. Electrode subassembly 100 further includes bonding piece 40, bonding piece 40's thickness is 15um ~ 25um, bonding piece 40 is connected the winding of first pole piece 10 terminates the end and covers electrode subassembly 100's partial surface.

In the embodiment of the application, the bonding member 40 is a hot melt adhesive, and can be selected as an ultrathin hot melt adhesive with the thickness of 15 um-25 um, and the material can be a rubber adhesive and is used together with PET. The bonding member 40 can generate viscosity under certain pressure (less than or equal to 3MPa) and temperature (less than or equal to 120 ℃). In other words, the hot melting temperature of the adhesive member 40 is less than or equal to 120 ℃ and the hot melting pressure is less than or equal to 3 MPa.

Referring again to fig. 1, the outer surface of the electrode assembly 100 includes a first plane 101, a second plane 102, a first arc surface 103, and a second arc surface 104. The first plane 101 is disposed opposite to the second plane 102 in a thickness direction (a direction indicated by an arrow a in fig. 1) of the electrode assembly 100, the first arc surface 103 is disposed opposite to the second arc surface 104 in a width direction (a direction indicated by an arrow B in fig. 1) of the electrode assembly 100, and the first arc surface 103 and the second arc surface 104 are connected between the first plane 101 and the second plane 102.

The winding end 13 of the first pole piece 10 is approximately located at the junction of the first plane 101 and the first arc surface 103, and the adhesive member 40 is connected to the winding end of the first pole piece 10 and attached to the first arc surface 103, so that the adhesive member 40 is prevented from increasing the thickness of the electrode assembly 100. In other embodiments, the winding end of the first pole piece may also be located on the first plane 101 or the second plane 102, and accordingly, the adhesive 40 is also attached to the first plane 101 or the second plane 102.

Further, in order to prevent the burrs generated by the lithium precipitation at the end of the second pole piece 20 from piercing the separation film 30 and connecting the first pole piece 10 to generate a short circuit, the winding terminal end of the second pole piece 20 extends out of the winding terminal end 13 of the first pole piece 10 along the pole piece winding direction, and the extending length L1 is greater than or equal to 2 mm. The winding terminal end 31 of the separation film 30 extends out of the winding terminal end of the second pole piece 20 and is attached to the inner surface of the adhesive member 40, and the length L2 of the winding terminal end 31 of the separation film 30 extending out of the second pole piece 20 is greater than or equal to 4 mm. The winding end of the second pole piece 20 is covered by the winding end 31 of the separator to protect and insulate the winding end of the second pole piece 20.

Referring to fig. 1 and 3, the electrode assembly 100 further includes a first tab 50 and a second tab 60, the first tab 50 is connected to the first pole piece 10, and the second tab 60 is connected to the second pole piece 20. The projections of the first tab 50 and the second tab 60 do not overlap in the thickness direction of the electrode assembly 100, and the first tab 50 and the second tab 60 protrude from the same end of the electrode assembly 100 in the length direction (the direction indicated by the arrow C in fig. 3) of the electrode assembly 100. In other embodiments, the first tab 50 and the second tab 60 may protrude from different ends of the electrode assembly 100, but the present application is not limited thereto.

Further, a first empty foil area 14 is disposed at a winding start end of the first pole piece 10, a second empty foil area 23 is disposed at a winding start end of the second pole piece 20, the first tab 50 is disposed in the first empty foil area 14, and the second tab 60 is disposed in the second empty foil area 23. The electrode assembly 100 includes a first insulating member 70, and the first insulating member 70 is disposed in the first empty foil region 14 and covers the first tab 50 to prevent a burr on the first tab 50 from piercing the separator 30 and contacting the second pole piece 20 to cause a short circuit. In an alternative embodiment, the first insulating member 70 may be an insulating tape, extending from the first tab 50 to the beginning of the first active material layer 12, and covering almost the entire first empty foil region 14, so that the first empty foil region 14 is effectively protected from cracking, short circuit, and the like.

In an alternative embodiment, the second empty foil area 23 extends out of the first empty foil area 14, and the second tab 60 is disposed in the area where the second empty foil area 23 extends out of the first empty foil area 14, so that even if the burr on the second tab 60 pierces through the isolation film 30, the second tab 60 contacts the second pole piece 20, and no short circuit occurs due to contact with the first pole piece 10. The electrode assembly 100 further includes a second insulating member 80, and the second insulating member 80 covers the end of the first empty foil region 14 to prevent burrs at the end of the first empty foil region 14 from piercing the separation film 30 and contacting the second electrode sheet 20.

Referring to fig. 2, in one embodiment of the present application, the first tab 50 is disposed on the first current collector 11 in a region coated with the first active material layer 12, and the second tab 60 is disposed on the second current collector 21 in a region coated with the second active material layer 22. First insulators 70 are arranged at the positions of the first pole lug 50 and the second pole lug 60, so that the problem of short circuit is avoided. When the first tab 50 and the first current collector 11 are connected, a portion of the first active material layer 12 needs to be removed first, so that a portion of the first current collector 11 exposes the first active material layer 12, and then the first tab 50 is welded to the exposed portion of the first current collector 11. The second tab 60 is connected to the second current collector 21 in a similar manner and will not be described in detail herein.

In other embodiments, the first tab 50 and the second tab 60 may be disposed one in a hollow foil region at the roll center of the electrode assembly 100, and the other in other positions of the pole piece, which is not limited in this application.

Referring to fig. 4 and 5, the positions indicated by the dashed lines are cutting positions in the manufacturing process of two adjacent first pole pieces 10. When the first tab 50 is disposed in the first empty foil region 14, since the outermost ring of the electrode assembly of the comparative example is disposed with a section of empty aluminum foil, the length L3 of the empty aluminum foil region in the comparative example shown in fig. 4 is significantly greater than the length L4 of the empty aluminum foil region in the embodiment of the present application shown in fig. 5, and the length L4 of the empty aluminum foil region in the embodiment of the present application only needs to meet the parameter requirement of the winding start end of the electrode assembly 100, which not only saves the consumables of the aluminum foil, but also removes the outermost ring of the empty aluminum foil, thereby improving the energy density and the safety performance of the electrode assembly 100 in use scenes such as falling.

Referring to fig. 6 and 7, when the first tab 50 is disposed in the area of the first current collector 11 coated with the first active material layer 12, since the outermost ring of the electrode assembly of the comparative example is provided with a section of empty aluminum foil, in the comparative example shown in fig. 6, a section of single-sided area and a section of empty aluminum foil exist between two adjacent first electrode sheets 10, and the single-sided area is the winding termination end 13 of the first electrode sheet 10, whereas in the embodiment of the present application shown in fig. 7, the empty aluminum foil between two adjacent first electrode sheets 10 is eliminated and only a section of single-sided area (the winding termination end 13 of the first electrode sheet 10) exists, so that the first active material layer 12 on the lower surface of the first current collector 11 can be continuous, the manufacturing process of the first electrode sheets 10 is simplified, and the production efficiency.

Referring to fig. 8, in a comparative example, a partially empty aluminum foil 105 (having no active material coating on both sides) was present at the outer tail of the electrode assembly, and an insulating tape 106 was attached to the coated edge of the tail and the empty aluminum foil at the tail. The empty aluminum foil 105 and the insulating tape 106 are located at the second plane 102 of the electrode assembly.

In conjunction with the examples of the present application described above, and with reference to the comparative examples described above, the energy density increasing ratios of the electrode assemblies 100 obtained using the respective examples were measured as shown in the following tables.

When the thickness of the aluminum foil is 10 um:

when the thickness of the aluminum foil is 12 um:

drop test data of the electrode assemblies of the comparative example and the example of the present application are shown in the following table.

The basic parameters of the electrode assemblies of the examples and comparative examples in the first set of tests were as follows:

cell capacity: 3200 mAh; chemical system 4.35V; s \ A overlap: 2.0 mm. S: an isolation film; a: an anode; overhang: 2.0mm directs separator widths 2mm greater than anode membrane widths. The anode diaphragm is a first pole piece.

First set of test data:

the basic parameters of the electrode assemblies of the examples and comparative examples in the second set of tests were as follows:

cell capacity: 4000 mAh; chemical system 4.35V; s \ A overlap: 2.0 mm.

Second set of test data:

categories	No damage to package	Isolating film folding	Smoking/ignition	By the ratio
					Examples	0/20	1/20	0/20	95％
Comparative example	1/20	3/20	0/20	80％

In the examples of the present application, in combination with fig. 4 to 8 and the data in the above-mentioned surfaces, compared with the comparative examples, the empty-free aluminum foil design of the outermost ring of the electrode assembly 100, in which the winding terminal end of the first pole piece 10 and a portion of the outer surface of the electrode assembly 100 are connected by the adhesive 40, reduces the thickness of the electrode assembly 100 while improving the energy density and the drop safety.

Referring to fig. 9, an embodiment of the present application further provides a battery 200, which includes a package body 201 and the electrode assembly 100 in the embodiment, wherein the electrode assembly 100 is accommodated in the package body 201, and tabs of the electrode assembly 100 extend out of the package body 201.

Although the present application has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the present application.