CN214477801U

CN214477801U - Battery core, battery pack and electric equipment

Info

Publication number: CN214477801U
Application number: CN202120625462.8U
Authority: CN
Inventors: 吴顺和; 许虎; 宋华冰; 尹远
Original assignee: Ningde Amperex Technology Ltd
Current assignee: Ningde Amperex Technology Ltd
Priority date: 2021-03-26
Filing date: 2021-03-26
Publication date: 2021-10-22
Anticipated expiration: 2031-03-26

Abstract

The embodiment of the application relates to an electric core, battery package and consumer, electric core includes electrode assembly and wrapping bag, electrode assembly includes first pole piece, second pole piece and diaphragm, first pole piece, diaphragm and second pole piece are rolled up and are formed electrode assembly, electrode assembly is including setting up in the first utmost point ear of first pole piece, and set up in the second utmost point ear of second pole piece, first utmost point ear and second utmost point ear all stretch out from the wrapping bag along first direction, winding structure has flat portion and flexion, electric core still includes the bolster, the bolster is located between first surface and the wrapping bag, first surface is that the outermost circle of flexion is close to a surface of wrapping bag. The battery cell also comprises a bonding piece, wherein the winding tail end of the electrode assembly is bonded with the electrode assembly body; to secure the winding end to the electrode assembly body. Through set up the bolster between the flexion of electrode subassembly and wrapping bag, then when electric core falls, the bolster protects easy impaired flexion in to electrode subassembly, can effectively improve falling of electric core impaired.

Description

Battery core, battery pack and electric equipment

Technical Field

The embodiment of the application relates to the technical field of batteries, in particular to a battery core, a battery pack and electric equipment.

Background

The battery cell is a device that converts external energy into electric energy and stores the electric energy in the battery cell so as to supply power to external electric equipment (such as portable electronic equipment) at a required time. At present, the battery cell is widely applied to electric equipment such as unmanned aerial vehicles, mobile phones, flat panels, and notebook computers. Generally, the battery cell includes an electrode assembly, a package bag, a first tab and a second tab. The electrode assembly is contained in the packaging bag and comprises a first pole piece, a diaphragm and a second pole piece, the diaphragm is located between the first pole piece and the second pole piece, the first pole piece, the diaphragm and the second pole piece are wound into a winding structure together, a first pole lug is connected with the first pole piece, a second pole lug is connected with the second pole piece, and the first pole lug and the second pole lug both extend out of the packaging bag along a first direction.

In the process of implementing the present application, the applicant of the present application finds that: the packaging bag and the electrode assembly are not protected, and when the battery core falls, the electrode assembly and the packaging bag are easily damaged.

SUMMERY OF THE UTILITY MODEL

In view of the above problems, embodiments of the present application provide a battery cell, a battery pack, and an electrical device, which overcome the above problems or at least partially solve the problem that the battery cell is easily damaged when falling.

According to an aspect of the embodiments of the present application, there is provided an electrical core, including an electrode assembly, a packaging bag for accommodating the electrode assembly, and a buffer member, wherein the electrode assembly includes a first pole piece, a second pole piece, a diaphragm located between the first pole piece and the second pole piece, a first tab, and a second tab. The first pole piece, the diaphragm and the second pole piece are wound to form the electrode assembly, the first pole lug is arranged on the first pole piece, the second pole lug is arranged on the second pole piece, the first pole lug and the second pole lug both extend out of the packaging bag along a first direction, the winding structure is provided with a flat part and a bent part, the buffer part is positioned between a first surface and the packaging bag, wherein the first surface is a surface of the packaging bag, which is close to the outermost circle of the bent part, the first surface is bent and arranged, and the first surface is parallel to the first direction; wherein an outermost circle of the bending portion is a circle of the bending portion away from a central axis of the electrode assembly, wherein the central axis of the electrode assembly is parallel to the first direction; the battery cell further comprises a bonding piece, and the bonding piece is bonded with the winding tail end of the electrode assembly and the electrode assembly body; to secure the winding end to the electrode assembly body. Set up the bolster between the flexion of the electrode subassembly of electricity core and the wrapping bag, then when electric core falls, the bolster protects easy impaired flexion in to the electrode subassembly to can effectively improve falling of electricity core impaired.

In an optional mode, the buffer member is arranged in a bent mode, and the buffer member covers the first surface, so that the protection effect of the buffer member on the battery cell is good.

In an alternative mode, the outermost turn of the curved portion has a second surface, the second surface is disposed curved, and the second surface is parallel to the first direction; the cell also includes a guard positioned between the second surface and the central axis of the electrode assembly. Through setting up the protection piece to the protective effect to electric core is good.

In an optional mode, the protection part is arranged in a bent mode, and the protection part covers the second surface, so that the protection effect of the protection part on the battery cell is good.

In an optional mode, an outermost ring of the bending portion is a part of an outermost ring of the first pole piece, a part, located at the outermost ring of the bending portion, of the outermost ring of the first pole piece includes a first current collector and a first active material, the first active material is disposed on the first current collector, and the protection element has a lithium ion permeability, so that the protection element is disposed to obtain a good protection effect on the battery cell, and a capacity loss of the battery cell caused by the disposition of the protection element can be reduced.

In an alternative, the buffer member is provided with an extension portion extending to the flat portion in the second direction, so that an area where the curved portion and the flat portion are excessive is also protected.

In an alternative mode, the second direction is parallel to the flat portion, and the length of the extension portion along the second direction is greater than 2 mm, so that the connection and fixation of the extension portion and the electrode assembly can be facilitated.

In an alternative mode, the second direction is parallel to the flat portion, and the length of the extension portion along the second direction is greater than 5 mm, so that the connection and fixation of the extension portion and the electrode assembly are facilitated.

In an optional mode, the first tab and the first pole piece are located the part of flat portion is connected, the second tab and the second pole piece are located the part of flat portion is connected, in the second direction, the extension portion with first tab or second tab be close to the one end of extension portion has the clearance to set up the bolster on the one hand and protected electric core, on the other hand, the extension portion of bolster has offset the size of first tab or second tab in the third direction, for the condition that extension portion overlaps with first tab or second tab or all overlap in the second direction, electric core is little in the size of third direction, wherein, the third direction is perpendicular with the first direction, and the third direction is perpendicular with flat portion.

In an optional mode, the buffer member is bonded to the packaging bag, so that protection of the battery cell by the buffer member is enhanced.

In an alternative form, the buffer is bonded to the electrode assembly to enhance protection of the buffer from the cell.

In an optional mode, the quantity of flexion is two, two the flexion is located respectively the both sides of flat portion, the quantity of bolster is two, one the bolster sets up in one the flexion all sets up the bolster at two flexion, and is effectual to the holistic protection of electric core.

According to an aspect of the embodiments of the present application, there is provided a battery pack including the battery cell described above.

According to an aspect of the embodiments of the present application, there is provided an electric device including a load and the above-mentioned battery pack, the load being connected to the battery pack.

The beneficial effects of the embodiment of the application are that: the utility model provides a battery core, battery package and consumer, battery core include electrode subassembly, hold electrode subassembly's wrapping bag and bolster. The electrode assembly is formed by winding a first pole piece, a second pole piece and a diaphragm. The first pole piece is connected with a first pole lug, and the second pole piece is connected with a second pole lug. The electrode assembly has a flat portion and a curved portion. The bolster sets up between flexion and wrapping bag, sets up the bolster through setting up between the flexion of the electrode subassembly of electric core and wrapping bag, then when electric core falls, the bolster protects easy impaired flexion in to electrode subassembly to can effectively improve falling of electric core impaired, and because the setting up of bolster has improved the atress distribution of electric core when the pressurized, the expansion ratio of electric core is little, and the deformation risk of electric core is low.

Drawings

One or more embodiments are illustrated by way of example in the accompanying drawings, which correspond to the figures in which like reference numerals refer to similar elements and which are not to scale unless otherwise specified.

Fig. 1 is a schematic diagram of an implementation manner in which a battery cell provided in an embodiment of the present application does not include a packaging bag;

fig. 2 is a schematic diagram of one direction in which a battery cell provided by an embodiment of the present application does not include a packaging bag;

fig. 3 is a schematic diagram of another implementation manner in which a battery cell provided in an embodiment of the present application does not include a packaging bag;

fig. 4 is a schematic diagram of another implementation manner in which a battery cell provided in an embodiment of the present application does not include a packaging bag;

FIG. 5 is an enlarged schematic view of portion A of FIG. 4 according to an embodiment of the present disclosure;

fig. 6 is a schematic diagram of another implementation manner in which a battery cell provided in an embodiment of the present application does not include a packaging bag;

fig. 7 is a schematic diagram of another implementation manner in which a battery cell provided in an embodiment of the present application does not include a packaging bag;

fig. 8 is a schematic diagram of a battery cell 1 provided in an embodiment of the present application;

fig. 9 is a schematic diagram of a battery cell 2 provided in an embodiment of the present application;

fig. 10 is a schematic diagram of a battery cell 3 provided in an embodiment of the present application;

fig. 11 is a schematic diagram of a battery cell 4 provided in an embodiment of the present application;

fig. 12 is a schematic diagram of a battery cell 5 provided in an embodiment of the present application;

fig. 13 is a schematic diagram of a battery cell 6 provided in an embodiment of the present application.

Detailed Description

In order to facilitate an understanding of the present application, the present application is described in more detail below with reference to the accompanying drawings and specific embodiments. 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 be present. The terms "vertical," "horizontal," "left," "right," "inner," "outer," and the like as used herein are for descriptive 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 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 "and/or" includes any and all combinations of one or more of the associated listed items.

Referring to fig. 1, a battery cell 100 includes: the electrode assembly 10, the packaging bag for accommodating the electrode assembly 10, the buffer member 20, the protection member 30, and the adhesive member 40, wherein the buffer member 20 and the protection member 30 are used for protecting the electrode assembly 10, and the adhesive member 40 is used for fixing the winding end to the electrode assembly body.

Referring to fig. 1 and 2, the electrode assembly 10 includes a first pole piece 101, a second pole piece 102, and a separator 103 disposed between the first pole piece 101 and the second pole piece 102, and the first pole piece 101, the separator 103, and the second pole piece 102 are wound together to form the electrode assembly 10. The electrode assembly 10 further includes a first tab 104 disposed on the first pole piece 101, and a second tab 105 disposed on the second pole piece 102, wherein the first tab 104 and the second tab 105 both extend from the package in a first direction L1.

Referring to fig. 3 for the first pole piece 101, in some embodiments, a portion of the first pole piece 101 includes a first current collector 1011 and a first active material 1012, the first active material 1012 is disposed on the first current collector 1011, and another portion of the first pole piece 101 also includes the first current collector 1011 and the first active material 1012, wherein another portion of the first pole piece 101 is located at a winding start end of the wound electrode assembly 10, and another portion of the first pole piece 101 is located at a winding tail end of the wound electrode assembly 10.

Here, the "winding start end" in the present application refers to an end of the electrode assembly 10, the first pole piece 101, the second pole piece 102, or the diaphragm 103 where winding starts.

Here, the "winding end" in the present application refers to an end of the electrode assembly 10, the first pole piece 101, the second pole piece 102, or the separator 103 where winding is completed.

It is worth noting that in some embodiments, a portion of the first pole piece 101 includes only the first current collector 1011, and another portion of the first pole piece 101 includes the first current collector 1011 and the first active material 1012, wherein another portion of the first pole piece 101 is located at a winding start end of the electrode assembly 10 formed by winding, and a portion of the first pole piece 101 is located at a winding end of the electrode assembly 10 formed by winding.

Referring to fig. 4, in some embodiments, a portion of the second pole piece 102 includes a second current collector 1021 and a second active material 1022, the second active material 1022 is disposed on the second current collector 1021, and another portion of the second pole piece 102 also includes the second current collector 1021 and the second active material 1022, wherein another portion of the second pole piece 102 is located at a winding start end of the wound electrode assembly 10, and a portion of the second pole piece 102 is located at a winding tail end of the wound electrode assembly 10.

It should be noted that, in some embodiments, a portion of the second pole piece 102 includes only the second current collector 1021, and another portion of the second pole piece 102 includes the second current collector 1021 and the second active material 1022, wherein another portion of the second pole piece 102 is located at a winding start end of the wound electrode assembly 10, and a portion of the second pole piece 102 is located at a winding end of the wound electrode assembly 10.

The first tab 104 may be integrally formed with the first current collector 1011 of the first pole piece 101, or the first tab 104 may be welded to the first pole piece 101 by welding or the like.

The second tab 105 may be integrally formed with the second current collector 1021 in the second pole piece 102, or the second tab 105 may be welded to the second pole piece 102 by welding or the like.

Referring to fig. 1, the electrode assembly 10 formed by winding the first pole piece 101, the separator 103 and the second pole piece 102 together has a flat portion 10a and a bent portion 10b, wherein the flat portion 10a is a portion of the first pole piece 101, the second pole piece 102 or the separator 103 extending straight after winding, and the bent portion 10b is a portion of the first pole piece 101, the second pole piece 102 or the separator 103 extending bent after winding.

Referring to fig. 2, 4 and 5, the outermost circle 10b1 of the bent portion 10b is a circle of the bent portion 10b away from the central axis S1 of the electrode assembly 10, wherein the central axis S1 of the electrode assembly 10 is parallel to the first direction L1. The outermost turn 10b1 of the bend has a first surface 10b11 and a second surface 10b 12.

The first surface 10b11 is a surface of the outermost turn 10b1 of the bending portion close to the packaging bag, the first surface 10b11 is arranged in a bending manner, and the first surface 10b11 is parallel to the first direction L1.

The second surface 10b12 is curved, and the second surface 10b12 is parallel to the first direction L1. That is, the second surface 10b12 is disposed opposite the first surface 10b11, and the second surface 10b12 is disposed away from the package relative to the first surface 10b 11.

Please refer to fig. 3, fig. 4, fig. 6, and fig. 7, respectively, where the outermost turn 10b1 of the bent portion may be a portion of the outermost turn 101a of the first pole piece, a portion of the outermost turn 102a of the second pole piece, or the separator 103, where a portion of the outermost turn 101a of the first pole piece located at the outermost turn 10b1 of the bent portion may include the first current collector 1011 and the first active material 1012, or may include only the first current collector 1011 and not include the first active material 1012. A part of the outermost turn 10b1 of the outermost turn 102a of the second pole piece located at the bent portion may include the second current collector 1021 and the second active material 1022, or may include only the second current collector 1021 and not the second active material 1022.

It should be noted that, in some embodiments, the number of the curved portions 10b is two, and the two curved portions 10b are respectively located on two sides of the flat portion 10 a.

The electrode assembly 10 is provided with two bent portions 10b, referring to fig. 3 and 4, an outermost turn 10b1 of one of the bent portions may include a portion of an outermost turn 101a of the first pole piece, wherein the portion of the outermost turn 101a of the first pole piece located at the outermost turn 10b1 of one of the bent portions includes a first current collector 1011 and a first active material 1012; the outermost turn 10b1 of the other bend may comprise a portion of the outermost turn 101a of the first pole piece, wherein the outermost turn 101a of the first pole piece is located at a portion of the outermost turn 10b1 of the other bend that comprises only the first current collector 1011.

It is understood that the electrode assembly 10 is provided with two bent portions 10b, wherein the outermost turn 10b1 of one bent portion may include a portion of the outermost turn 102a of the second pole piece, wherein a portion of the outermost turn 102a of the second pole piece located at the outermost turn 10b1 of one bent portion includes the second current collector 1021 and the second active material 1022; the outermost turn 10b1 of the another bend may include a portion of the outermost turn 102a of the second pole piece, wherein the portion of the outermost turn 102a of the second pole piece located at the outermost turn 10b1 of the another bend includes only the second current collector 1021.

It is understood that the electrode assembly 10 is provided with two bent portions 10b, wherein the outermost turn 10b1 of one of the bent portions may include a portion of the outermost turn 101a of the first pole piece, wherein a portion of the outermost turn 101a of the first pole piece located at the outermost turn 10b1 of one of the bent portions includes the first current collector 1011 and the first active material 1012; the outermost turn 10b1 of the another bend may include a portion of the outermost turn 102a of the second pole piece, wherein the portion of the outermost turn 102a of the second pole piece located at the outermost turn 10b1 of the another bend includes only the second current collector 1021.

It is understood that the electrode assembly 10 is provided with two bent portions 10b, wherein the outermost turn 10b1 of one bent portion may include a portion of the outermost turn 102a of the second pole piece, wherein a portion of the outermost turn 102a of the second pole piece located at the outermost turn 10b1 of one bent portion includes the second current collector 1021 and the second active material 1022; the outermost turn 10b1 of the other bend may comprise a portion of the outermost turn 101a of the first pole piece, wherein the outermost turn 101a of the first pole piece is located at a portion of the outermost turn 10b1 of the other bend that comprises only the first current collector 1011.

With respect to the electrode assembly 10 and the buffer member 20 described above, referring to fig. 4 and 5, the buffer member 20 is located between the first surface 10b11 of the outermost turn 10b1 of the bent portion of the electrode assembly 10 and the package bag.

Since the bent portion 10b of the electrode assembly 10 is a portion bent and extended after the first or

second pole piece

101 or 102 or the separator 103 is wound, stress concentration is easily generated at the bent portion 10b, and the battery cell 100 is not easily damaged when it is dropped by providing the buffer member 20 between the first surface 10b11 of the outermost turn 10b1 of the bent portion and the packaging bag.

Since the bending portion 10b is small in size in the third direction L3 relative to the flat portion 10a, wherein the third direction L3 is perpendicular to the first direction L1, and the third direction L3 is perpendicular to the flat portion 10a, by providing the buffer member 20 in the bending portion 10b, the size difference of each portion of the electrode assembly 10 in the third direction L3 can be improved, the stress distribution of the battery cell 100 can be improved when the battery cell 100 is compressed, and the stress of the flat portion 10a and the bending portion 10b of the electrode assembly 10 can be optimized, so that the risk of full charge and cyclic deformation of the battery cell 100 can be reduced.

It should be noted that, in some embodiments, the buffer member 20 is disposed in a bent manner, and the buffer member 20 covers the first surface 10b11, so that the buffer member 20 has a good protection effect on the battery cell 100.

It should be noted that in some embodiments, the buffer member 20 is bonded to the pouch, or the buffer member 20 is bonded to the pouch and the electrode assembly 10, respectively.

In some embodiments, the buffer member 20 is provided with an extension 201 extending to the flat portion 10a along the second direction L2, and the extension 201 is used for shielding the connection between the flat portion 10a and the curved portion 10 b.

The second direction L2 may be any direction in which the bumper 20 extends toward the flat portion 10a, and when the second direction L2 is parallel to the flat portion 10a, the extending portion 201 has the best protection effect on the connection between the flat portion 10a and the curved portion 10 b.

When the second direction L2 is parallel to the flat portion 10a, the length of the extending portion 201 in the second direction L2 is greater than 2 mm, and preferably, the length of the extending portion 201 in the second direction L2 is greater than 5 mm.

It should be noted that in some embodiments, the extension 201 is bonded to the pouch, or the extension 201 is bonded to the pouch and the electrode assembly 10, respectively.

It is understood that the buffer member 20 is bonded to the electrode assembly 10, and when the extension 201 is bonded to the electrode assembly 10, since the extension 201 is located at the flat portion 10a of the electrode assembly 10, the buffer member 20 is easily bonded to the electrode assembly 10.

It should be noted that, referring to fig. 4, in some embodiments, the first tab 104 is connected to the portion of the first pole piece 101 located on the flat portion 10a, the second tab 105 is connected to the portion of the second pole piece 102 located on the flat portion 10a, and a gap 2011 is formed between the extension 201 and one end of the first tab 104 or one end of the second tab 105 close to the extension 201 in a second direction L2 parallel to the flat portion 10 a. That is, in the second direction L2, the extending portion 201 does not extend to the first tab 104 or the second tab 105, so that the size of the battery cell 100 in the third direction L3 is small, on one hand, the dropping damage of the battery cell 100 is improved by providing the buffer 20, on the other hand, the size of the battery cell 100 in the third direction L3 is not increased, and the application scenario of the battery cell 100 is expanded, where the third direction L3 is perpendicular to the first direction L1, the third direction L3 is perpendicular to the flat portion 10a, and when the second direction L2 is parallel to the flat portion 10a, the third direction L3 is perpendicular to the second direction L2.

It should be noted that the buffer material 20 is insulating, and the buffer material 20 has lithium ion permeability and the latter has lithium ion non-permeability.

When the number of the bent portions 10b is two, the number of the cushion members 20 is two, and one cushion member 20 is provided at one bent portion 10 b.

Of course, when the number of the bent portions 10b is two, the number of the cushion members 20 may be one, and the cushion member 20 may be provided in one of the bent portions 10 b.

With respect to the electrode assembly 10 and the protector 30, referring to fig. 3, 4 and 5, the protector 30 is located between the second surface 10b12 of the outermost turn 10b1 of the bent portion of the electrode assembly 10 and the central axis S1 of the electrode assembly 10. The outermost ring 10b1 of the bending portion is the first pole piece 101 or the second pole piece 102.

second pole piece

101 or 102 is wound, stress concentration is easily generated at the bent portion 10b, and the battery cell 100 is not easily damaged when it is dropped by providing the protector 30 between the second surface 10b12 of the outermost turn 10b1 of the bent portion and the central axis S1 of the electrode assembly 10.

Since the bending portion 10b is small in size in the third direction L3 relative to the flat portion 10a, wherein the third direction L3 is perpendicular to the first direction L1, and the third direction L3 is perpendicular to the flat portion 10a, by providing the protection member 30 in the bending portion 10b, the size difference of each portion of the electrode assembly 10 in the third direction L3 can be improved, the stress distribution of the battery cell 100 can be improved when the battery cell 100 is compressed, and the stress of the flat portion 10a and the bending portion 10b of the electrode assembly 10 can be optimized, so that the risk of full charge and cyclic deformation of the battery cell 100 can be reduced.

It should be noted that, in some embodiments, the protection member 30 is disposed in a bent manner, and the protection member 30 covers the second surface 10b12, so that the protection effect of the protection member 30 on the battery cell 100 is good.

Note that, in some embodiments, the protector 30 is bonded to the electrode assembly 10, for example, the protector 30 is bonded to the second surface 10b12, or the protector 30 is bonded to the second surface 10b12 and the portion of the electrode assembly 10 located at the bent portion 10b and near the outermost turn 10b1 of the bent portion, respectively.

In some embodiments, the protector 30 is provided with a damage prevention portion 301 extending to the flat portion 10a in the second direction L2, the damage prevention portion 301 serving to protect a connection of the flat portion 10a and the curved portion 10 b.

Here, the second direction L2 may be any direction in which the protection member 30 extends toward the flat portion 10a, and when the second direction L2 is parallel to the flat portion 10a, the protection effect of the damage preventing portion 301 on the connection portion between the flat portion 10a and the bent portion 10b is the best.

When the second direction L2 is parallel to the flat portion 10a, the length of the damage prevention part 301 in the second direction L2 is greater than 2 mm, and preferably, the length of the damage prevention part 301 in the second direction L2 is greater than 5 mm.

It should be noted that, referring to fig. 2 and 4, in some embodiments, the damage preventing part 301 is bonded to the electrode assembly 10, for example, the damage preventing part 301 is bonded to a surface of the outermost turn of the flat part 10a near the central axis S1 of the electrode assembly 10, or the damage preventing part 301 is bonded to a surface of the outermost turn of the flat part 10a near the central axis S1 of the electrode assembly 10, and the damage preventing part 301 is bonded to a portion of the electrode assembly 10 located at the flat part 10a and near the outermost turn of the flat part 10 a.

Wherein the outermost turn of the flat portion 10a is one turn of the flat portion 10a away from the central axis S1 of the electrode assembly 10, wherein the central axis S1 of the electrode assembly 10 is parallel to the first direction L1.

It is understood that the damage preventing part 301 is located at the flat part 10a of the electrode assembly 10 when the protection member 30 is bonded to the electrode assembly 10 and the damage preventing part 301 is bonded to the electrode assembly 10, thereby facilitating the bonding fixation of the protection member 30 to the electrode assembly 10.

It should be noted that, in some embodiments, the first tab 104 is connected to the portion of the first pole piece 101 located on the flat portion 10a, the second tab 105 is connected to the portion of the second pole piece 102 located on the flat portion 10a, and the damage prevention portion 301 and the end of the first tab 104 or the second tab 105 close to the damage prevention portion 301 have an interval space 3011 in the second direction L2 parallel to the flat portion 10 a. That is, in the second direction L2, the damage prevention part 301 does not extend to the first tab 104 and does not extend to the second tab 105, so that the size of the battery cell 100 in the third direction L3 is small, on one hand, the drop damage of the battery cell 100 is improved by providing the protection part 30, and on the other hand, the size of the battery cell 100 in the third direction L3 is not increased, so that the application scenario of the battery cell 100 is expanded, wherein the third direction L3 is a direction perpendicular to the first direction L1 and the second direction L2.

It is worth noting that in some embodiments, the guard 30 has lithium ion permeability. Referring to fig. 3, the outermost turn 10b1 of the bent portion is a portion of the outermost turn 101a of the first pole piece, a portion of the outermost turn 101a of the first pole piece located at the bent portion 10b1 includes a first current collector 1011 and a first active material 1012, and the first active material 1012 is disposed on the first current collector 1011, so that the protection member 30 has lithium ion permeability. Alternatively, the guard 30 has lithium ion permeability if the outermost turn 10b1 of the bent portion is a part of the outermost turn 102a of the second pole piece, a part of the outermost turn 102a of the second pole piece located at the bent portion, i.e., the outermost turn 10b1, includes the second current collector 1021 and the second active material 1022, and the second active material 1022 is disposed on the second current collector 1021. The protection element 30 has lithium ion permeability, so that the battery cell 100 can be protected from falling, and the capacity loss of the battery cell 100 caused by the arrangement of the protection element 30 can be reduced.

It is worth noting that in some embodiments, the guard 30 is provided with lithium ion non-permeability. In practical applications, the winding end of the wound electrode assembly 10 is located at the flat portion 10a, and the winding end of the electrode assembly 10 may be the winding end 101b of the first pole piece (see fig. 3), the winding end 102b of the second pole piece (see fig. 4), or the winding end 103b of the separator (see fig. 6), wherein, referring to fig. 3, when the winding end 101b of the first pole piece is not located between the winding end 102a of the second pole piece and the outermost turn 102a of the second pole piece, or, referring to fig. 1, when the winding end 101b of the first pole piece is adjacent to two layers of separators 103, the winding end 101b of the first pole piece only includes the first current collector 1011, referring to fig. 4, when the winding end 102b of the second pole piece is not located between the outermost turn 101a of the first pole piece, or when the winding end 102b of the second pole piece is adjacent to two layers of separators 103, the winding end 102b of the second pole piece only includes the second current collector 1021, and the shielding member 30 may have lithium ion impermeability instead of the ending green tape. Referring to fig. 3, when the first pole piece 101 is a positive pole piece, the dimension of the damage prevention part 301 extending from the guard 30 along the second direction L2 parallel to the flat portion 10a is larger than the dimension of the tail end of the first pole piece 101 along the second direction L2 parallel to the flat portion 10a, and the damage prevention part 301 is insulated, and when the damage prevention part 301 is adhered to the winding tail end 101b of the first pole piece and adhered to the outermost ring 102a of the second pole piece, the damage prevention part 301 can be used instead of the tail green tape.

In addition, when the number of the bent portions 10b is two, referring to fig. 3, the number of the shielding members 30 is two, and one shielding member 30 is disposed at one bent portion 10 b.

Of course, when the number of the bent portions 10b is two, the number of the shielding members 30 may be one, and referring to fig. 6, the shielding member 30 is disposed at one of the bent portions 10 b.

It should be noted that, in some embodiments, the protection member 30 may not be provided, and referring to fig. 7, the protection of the bent portion 10b of the electrode assembly 10 for the purpose of improving the dropping damage of the electrode assembly 10 can also be achieved.

Referring to fig. 1, the adhesive member 40 adheres the winding end of the electrode assembly to the electrode assembly body; to secure the winding end to the electrode assembly body. Wherein, in some embodiments, the electrode assembly body is the flat portion 10a of the electrode assembly 10.

For the convenience of the reader to understand the inventive concept of the embodiments of the present application, 5 specific battery cells, battery cell 1, battery cell 2, battery cell 3, battery cell 4, battery cell 5, and battery cell 6 are listed below for reference, where battery cell 6 is a comparative example.

Referring to fig. 8-13, the same structure for 6 cells listed is: the battery cell 100 includes an electrode assembly 10 and a packaging bag for accommodating the electrode assembly 10, the electrode assembly 10 includes a first pole piece 101, a second pole piece 102 and a diaphragm 103 located between the first pole piece 101 and the second pole piece 102, the first pole piece 101, the diaphragm 103 and the second pole piece 102 are wound to form the electrode assembly 10, the electrode assembly 10 further includes a first tab 104 disposed on the first pole piece 101 and a second tab 105 disposed on the second pole piece 102, the first tab 104 and the second tab 105 both extend out of the packaging bag along a first direction L1, the winding structure has a flat portion 10a and two bent portions 10b, the number of the bent portions 10b is two, and the two bent portions 10b are respectively located on two sides of the flat portion 10 a.

Referring to fig. 8 to 12, the battery cell 1 to 5 further includes a buffer 20, the buffer 20 is located between the first surface 10b11 and the package bag, wherein the first surface 10b11 is a surface of the outermost circle 10b1 of the bending portion, the first surface 10b11 is disposed in a bending manner, and the first surface 10b11 is parallel to the first direction L1; wherein the buffer member 20 is bonded to the electrode assembly 10 and the pouch, respectively; wherein the outermost circle 10b1 of the bent portion is one turn of the bent portion 10b away from the central axis S1 of the electrode assembly 10, wherein the central axis S1 of the electrode assembly 10 is parallel to the first direction L1. The number of the cushion members 20 is two, and one cushion member 20 is disposed at one bent portion 10 b. The extended portions 201 of the buffer member 20 are bonded to the package bag and the electrode assembly 10, respectively.

The battery cell 1, the battery cell 2, the battery cell 3, the battery cell 4, the battery cell 5 and the battery cell 6 are different as follows.

Battery cell 1: referring to fig. 8, the outermost circle 10b1 of the curved portion is a part of the outermost circle 102a of the second pole piece, the second pole piece 102 is a negative pole piece, the battery cell 1 includes a buffer 20-1 and a buffer 20-2, the buffer 20-1 is located at one curved portion 10b, the buffer 20-2 is located at the other curved portion 10b, the extending lengths of the buffer 20-1 and the buffer 20-2 are both 25 mm, and the extending portions 201 of the buffer 20-1 and the buffer 20-2 are both 5 mm in the second direction L2 parallel to the flat portion 10 a. The extending portions 201 of the buffers 20-1 and 20-2 have a gap 2011 with one end of the first tab 104 or the second tab 105 near the extending portion 201 in the second direction L2 parallel to the flat portion 10 a. The battery cell 1 further comprises a protection piece 30-1 and a protection piece 30-2, the protection piece 30-1 is located at one of the bent portions 10b, the protection piece 30-2 is located at the other of the bent portions 10b, the protection piece 30-1 and the protection piece 30-2 both have an extension length of 35 mm, the damage prevention parts 301 of the protection piece 30-1 and the protection piece 30-2 both have a dimension of 10 mm in a second direction L2 parallel to the flat portion 10a, and the damage prevention parts 301 of the protection piece 30-1 and the protection piece 30-2 have a spacing space 3011 in a second direction L2 parallel to the flat portion 10a from one end of the first tab 104 or the second tab 105 close to the damage prevention part 301. The protector 30-1 and the protector 30-2 are bonded to the second surface 10b12 of the outermost turn 10b1 of the bent portion and the portion of the electrode assembly 10 located at the bent portion 10b and near the outermost turn 10b1 of the bent portion, respectively. The damage preventing part 301 is bonded to a surface of the outermost turn of the flat part 10a near the central axis S1 of the electrode assembly 10, and the damage preventing part 301 is bonded to a portion of the electrode assembly 10 located at the flat part 10a and near the outermost turn of the flat part 10 a. The outermost turn 102a of the second pole piece is adjacent to the two layers of the separator 103 at the bent portion 10b, and the guard 30-1 and the guard 30-2 are provided with lithium ion impermeability.

And (3) battery cell 2: referring to fig. 9, the outermost circle 10b1 of one of the bent portions is a portion of the outermost circle 102a of the second pole piece, the second pole piece 102 is a negative pole piece, and a portion of the outermost circle 102a of the second pole piece, which is located in the outermost circle 10b1 of one of the bent portions, includes a second current collector 1021 and a second active material 1022; the outermost circle 10b1 of the other bending part is a part of the outermost circle 101a of the first pole piece, the first pole piece 101 is a positive pole piece, a part of the outermost circle 101a of the first pole piece, which is located at the outermost circle 10b1 of the other bending part, comprises a first current collector 1011, the winding end 101b of the first pole piece extends from the outermost circle 10b1 of the other bending part to the flat part 10a, and no diaphragm 103 is arranged between the winding end 101b of the first pole piece and the outermost circle 102a of the second pole piece. The battery cell 2 comprises a buffer 20-1 and a buffer 20-2, the buffer 20-1 is located at one of the bent portions 10b, the buffer 20-2 is located at the other bent portion 10b, the extending lengths of the buffer 20-1 and the buffer 20-2 are both 25 mm, and the extension portions 201 of the buffer 20-1 and the buffer 20-2 are both 5 mm in the second direction L2 parallel to the flat portion 10 a. The extending portions 201 of the buffers 20-1 and 20-2 have a gap 2011 with one end of the first tab 104 or the second tab 105 near the extending portion 201 in the second direction L2 parallel to the flat portion 10 a. The battery cell 2 further comprises a protection piece 30-1 and a protection piece 30-2, wherein the protection piece 30-1 is located at one of the bent portions 10b, the protection piece 30-2 is located at the other bent portion 10b, the extension length of the protection piece 30-1 is 35 mm, the extension length of the protection piece 30-2 is related to the size of the winding tail end 101b of the first pole piece in the second direction L2 parallel to the flat portion 10a, the size of the damage prevention part 301 of the protection piece 30-1 in the second direction L2 parallel to the flat portion 10a is 10 mm, and the damage prevention part 301 of the protection piece 30-1 has a spacing space 3011 in the second direction L2 parallel to the flat portion 10a from one end of the first pole lug 104 or the second pole lug 105 close to the damage prevention part 301. The dimension of the end of the damage prevention part 301 of the protection member 30-2 away from the winding end 101b of the first pole piece in the second direction L2 parallel to the flat part 10a is 10 mm, and the end of the protection member 30-2 away from the winding end 101b of the first pole piece has a spacing space 3011 in the second direction L2 parallel to the flat part 10a and the end of the first tab 104 or the second tab 105 close to the protection member. The dimension of the damage prevention part 301 of the protector 30-2 at the end close to the winding trailing end 101b of the first pole piece in the second direction L2 parallel to the flat portion 10a is larger than the dimension of the winding trailing end 101b of the first pole piece in the second direction L2 parallel to the flat portion 10a, and the damage prevention part 301 is insulated, and the protector 30-1 and the protector 30-2 are respectively bonded to the second surface 10b12 of the outermost turn 10b1 of the bent portion and the portion of the electrode assembly 10 located at the bent portion 10b and close to the outermost turn 10b1 of the bent portion. The damage preventing part 301 is bonded to a surface of the outermost turn of the flat part 10a near the central axis S1 of the electrode assembly 10, and the damage preventing part 301 is bonded to a portion of the electrode assembly 10 located at the flat part 10a and near the outermost turn of the flat part 10 a. The guard 30-1 is permeable to lithium ions, and the guard 30-2 is impermeable to lithium ions. The end of the damage prevention part 301 close to the winding ending part 101b of the first pole piece can be used instead of ending green glue.

And (3) battery cell: referring to fig. 10, the outermost circle 10b1 of one of the bent portions is a portion of the outermost circle 102a of the second pole piece, the second pole piece 102 is a negative pole piece, and a portion of the outermost circle 102a of the second pole piece, which is located in the outermost circle 10b1 of one of the bent portions, includes a second current collector 1021 and a second active material 1022; the outermost turn 10b1 of one of the other bends is part of the outermost turn 103a of the diaphragm, and the winding trailing end 103b of the diaphragm extends from the outermost turn 10b1 of the other of the bends to the flat 10 a. The battery cell 3 comprises a buffer 20-1 and a buffer 20-2, the buffer 20-1 is located at one of the bent portions 10b, the buffer 20-2 is located at the other bent portion 10b, the extending lengths of the buffer 20-1 and the buffer 20-2 are both 25 mm, and the extension portions 201 of the buffer 20-1 and the buffer 20-2 are both 5 mm in the second direction L2 parallel to the flat portion 10 a. The extending portions 201 of the buffers 20-1 and 20-2 have a gap 2011 with one end of the first tab 104 or the second tab 105 near the extending portion 201 in the second direction L2 parallel to the flat portion 10 a. The battery cell 3 further includes a protection member 30-1, the protection member 30-1 is located at one of the bent portions 10b, an extension length of the protection member 30-1 is 35 mm, a dimension of the damage prevention portion 301 of the protection member 30-1 in a second direction L2 parallel to the flat portion 10a is 10 mm, and the damage prevention portion 301 of the protection member 30-1 has a space 3011 from an end of the first tab 104 or the second tab 105 near the damage prevention portion 301 in a second direction L2 parallel to the flat portion 10 a. The protector 30-1 is bonded to the second surface 10b12 of the outermost turn 10b1 of the bent portion and the portion of the electrode assembly 10 located at the bent portion 10b and near the outermost turn 10b1 of the bent portion, respectively. The damage preventing part 301 is bonded to a surface of the outermost turn of the flat part 10a near the central axis S1 of the electrode assembly 10, and the damage preventing part 301 is bonded to a portion of the electrode assembly 10 located at the flat part 10a and near the outermost turn of the flat part 10 a. The guard 30-1 is permeable to lithium ions.

And (4) battery cell: referring to fig. 11, the outermost circle 10b1 of one of the bent portions is a portion of the outermost circle 102a of the second pole piece, the second pole piece 102 is a negative pole piece, and a portion of the outermost circle 102a of the second pole piece, which is located at the outermost circle 10b1 of one of the bent portions, includes a second current collector 1021 and a second active material 1022; the outermost turn 10b1 of the other bend is part of the outermost turn 102a of the second pole piece, a part of the outermost turn 102a of the second pole piece, which is located at the outermost turn 10b1 of the other bend, comprises a first current collector 1011, the winding end 102b of the second pole piece extends from the outermost turn 10b1 of the other bend to the flat part 10a, and no diaphragm 103 is arranged between the winding end 102b of the second pole piece and the outermost turn 102a of the second pole piece. The battery cell 4 comprises a buffer 20-1 and a buffer 20-2, the buffer 20-1 is located at one of the bent portions 10b, the buffer 20-2 is located at the other bent portion 10b, the extending lengths of the buffer 20-1 and the buffer 20-2 are both 25 mm, and the extension portions 201 of the buffer 20-1 and the buffer 20-2 are both 5 mm in the second direction L2 parallel to the flat portion 10 a. The extending portions 201 of the buffers 20-1 and 20-2 have a gap 2011 with one end of the first tab 104 or the second tab 105 near the extending portion 201 in the second direction L2 parallel to the flat portion 10 a. The battery cell 4 further comprises a protection piece 30-1 and a protection piece 30-2, the protection piece 30-1 is located at one of the bent portions 10b, the protection piece 30-2 is located at the other of the bent portions 10b, the protection piece 30-1 and the protection piece 302 each have an extended length of 35 mm, the protection piece 30-1 and the protection piece 302 each have a dimension of 10 mm in a second direction L2 parallel to the flat portion 10a, and the protection piece 30-1 and the protection piece 302 each have a space 3011 in a second direction L2 parallel to the flat portion 10a from an end of the first tab 104 or the second tab 105 near the protection piece 301. The protector 30-1 and the protector 30-2 are bonded to the second surface 10b12 of the outermost turn 10b1 of the bent portion and the portion of the electrode assembly 10 located at the bent portion 10b and near the outermost turn 10b1 of the bent portion, respectively. The damage preventing part 301 is bonded to a surface of the outermost turn of the flat part 10a near the central axis S1 of the electrode assembly 10, and the damage preventing part 301 is bonded to a portion of the electrode assembly 10 located at the flat part 10a and near the outermost turn of the flat part 10 a. The guard 30-1 is permeable to lithium ions, and the guard 30-2 is impermeable to lithium ions. The end of the damage prevention part 301 close to the winding ending end 102b of the second pole piece can be used instead of ending green glue.

And (3) battery cell 5: referring to fig. 12, the outermost turn 10b1 of one of the bends is part of the outermost turn 103a of the diaphragm, the outermost turn 10b1 of the other bend is part of the outermost turn 103a of the diaphragm, and the winding trailing end 103b of the diaphragm extends from the outermost turn 10b1 of the other of the bends to the flat portion 10 a. The battery cell 5 comprises a buffer 20-1 and a buffer 20-2, the buffer 20-1 is located at one of the bent portions 10b, the buffer 20-2 is located at the other bent portion 10b, the extending lengths of the buffer 20-1 and the buffer 20-2 are both 25 mm, and the extension portions 201 of the buffer 20-1 and the buffer 20-2 are both 5 mm in the second direction L2 parallel to the flat portion 10 a. The extending portions 201 of the buffers 20-1 and 20-2 have a gap 2011 with one end of the first tab 104 or the second tab 105 near the extending portion 201 in the second direction L2 parallel to the flat portion 10 a.

And (3) battery cell 6: referring to fig. 13, the battery cell 6 includes a buffer 20-3 and a protection member 30-3, the buffer 20-3 is disposed between a surface of the flat portion 10a, which is away from the central axis S1 of the electrode assembly 10, and the packaging bag, and the buffer 20-3 is respectively bonded to the packaging bag and a surface of the flat portion 10a, which is away from the central axis S1 of the electrode assembly 10; the protector 30-3 is disposed between the other surface of the outermost turn of the flat portion 10a near the central axis S1 of the electrode assembly 10 and the central axis S1 of the electrode assembly 10, the protector 30-3 is bonded to the other surface of the outermost turn of the flat portion 10a near the central axis S1 of the electrode assembly 10, and the protector 30-3 is bonded to the electrode assembly 10 at the flat portion 10a and at a portion of the outermost turn near the flat portion 10 a. The buffer 20-3 partially overlaps the first tab 104 and/or the second tab 105. The guard 30-3 partially overlaps the first tab 104 and/or the second tab 105.

The packaging bags of the battery cells 1 to 6 each have a first outer surface, a second outer surface, a first corner, a second corner, a third corner and a fourth corner, wherein in the second direction L2, the first outer surface and the second outer surface are respectively parallel to the flat portion 10a of the electrode assembly 10, the first corner is one end of one of the bent portions 10b close to the first tab 104 or the second tab 105 in the first direction L1, the second corner is one end of one of the bent portions 10b close to the first tab 104 or the second tab 105 in the first direction L1, the third corner is one end of the other bent portion 10b close to the first tab 104 or the second tab 105 in the first direction L1, and the fourth corner is one end of the other bent portion 10b close to the first tab 104 or the second tab 105 in the first direction L1.

And performing a 1.8-meter drop test on the battery cell 1-6, wherein the drop test is performed at a height of 1.8 meters, the vertical distance from a drop starting point of the battery cell 100 to a drop surface is 1.8 meters, the drop test is performed for 3 times of 18 times in total, the 1-round drop test is performed for the first outer surface, the second outer surface, the first corner, the second corner, the third corner and the fourth corner of the battery cell 100 to the drop surface in sequence, and the judgment standard of the drop test is no fire, no explosion and no liquid leakage. Each of the battery cells 100 uses 10 battery cells 100 to perform a drop test. The test result shows that the cells 1 to 6 pass the 1.8 m drop test.

And performing a 1.2-meter drop test on the battery cell 1-6, wherein the drop test is performed at a height of 1.2 meters, the vertical distance from a drop starting point of the battery cell 100 to a drop surface is 1.2 meters, the drop test is performed for 3 times of 18 times in total, the 1-round drop test is performed for the first outer surface, the second outer surface, the first corner, the second corner, the third corner and the fourth corner of the battery cell 100 to the drop surface in sequence, and the judgment standard of the drop test is no fire, no explosion and no liquid leakage. Each of the battery cells 100 uses 10 battery cells 100 to perform a drop test. The test result shows that the cells 1-6 pass the 1.2 m drop test.

The thickness h1 in the third direction L3 after the full charge of the battery cell 1-6 is respectively tested, the thickness h2 in the third direction L3 after the half charge of the battery cell 1-6 is respectively tested, and the expansion rate is respectively calculated, wherein the expansion rate is (h1-h2)/h 2. The results were achieved with cells 1-5 having an expansion of 2% and cell 6 having an expansion of 3%. Since the buffer member 20 and/or the protection member 30 of the battery cell 1-5 are located at the bent portion 10b, the dimension of the bent portion 10b in the third direction L3 is smaller than the dimension of the flat portion 10a in the third direction L3, and the setting of the buffer member 20 and/or the protection member 30 improves the difference between the dimensions of the bent portion 10b and the flat portion 10a in the third direction L3, the stress distribution of the battery cell 100 is optimized when the battery cell 1-5 is pressed, the expansion rate of the battery cell 1-5 is smaller than that of the comparative example battery cell 6, and the risk of deformation of the battery cell 1-5 is low.

In summary, in the second direction L2 where the flat portion 10a is parallel, a gap 2011 is formed between the extending portion 201 of the buffer 20 and the first tab 104 or the second tab 105, and a space 3011 is formed between the protection portion at least one end of the protection member 30 and the first tab 104 or the second tab 105, so that the size of the battery cell 100 in the third direction L3 is not increased in the battery cells 1-5 relative to the battery cell 6, and the application range of the battery cells 1-5 is wide. In addition, the buffer member 20 and/or the protection member 30 of the battery cell 1-5 are/is disposed between the bending portion 10b and the packaging bag, so that the drop damage of the battery cell 1-5 can be effectively improved. Finally, since the arrangement of the buffer member 20 and/or the protection member 30 improves the stress distribution of the battery cell 100 when being pressed, the expansion rate of the battery cells 1 to 5 is small, and the risk of deformation of the battery cells 1 to 5 is low.

In the embodiment of the present application, by providing the buffer 20 between the bending portion 10b of the electrode assembly 10 of the battery cell 100 and the packaging bag, when the battery cell 100 falls, the buffer 20 protects the bending portion 10b of the electrode assembly 10, which is easily damaged, so that the falling damage of the battery cell 100 can be effectively improved, and the stress distribution of the battery cell 100 when being pressed is improved due to the arrangement of the buffer 20, the expansion rate of the battery cell 100 is small, and the deformation risk of the battery cell 100 is low. When the gap 2011 is formed between the extension 201 of the buffer 20 and the first tab 104 or the second tab 105, the size of the battery cell 100 in the third direction L3 is not increased, and the application range of the battery cell 100 is wide.

The embodiment of the present application further provides an embodiment of a battery pack, where the battery pack includes the battery core 100. For the specific structure and function of the battery cell 100, reference may be made to the above embodiments, and details are not repeated here.

The embodiment of the application also provides an embodiment of an electric device, wherein the electric device comprises a load and the battery pack. The battery pack is used to power a load.

The electric equipment can be an energy storage product, a mobile phone, a tablet, an unmanned aerial vehicle, a single wheel or an electric vehicle with more than two wheels, or an electric cleaning tool and the like.

For example, for the above-mentioned unmanned aerial vehicle, a battery pack is mounted on the unmanned aerial vehicle, and the battery pack is used for supplying power to loads including a flight system, a control system, a camera system, and the like on the unmanned aerial vehicle.

It should be noted that the description of the present application and the accompanying drawings set forth preferred embodiments of the present application, however, the present application may be embodied in many different forms and is not limited to the embodiments described in the present application, which are not intended as additional limitations to the present application, but are provided for the purpose of providing a more thorough understanding of the present disclosure. Moreover, the above-mentioned technical features are combined with each other to form various embodiments which are not listed above, and all the embodiments are regarded as the scope described in the present specification; further, modifications and variations may occur to those skilled in the art in light of the foregoing description, and it is intended to cover all such modifications and variations as fall within the scope of the appended claims.

Claims

1. A battery cell comprises an electrode assembly and a packaging bag for accommodating the electrode assembly, wherein the electrode assembly comprises a first pole piece, a second pole piece and a diaphragm positioned between the first pole piece and the second pole piece, the first pole piece, the diaphragm and the second pole piece are wound to form the electrode assembly, the electrode assembly further comprises a first pole lug arranged on the first pole piece and a second pole lug arranged on the second pole piece, and the first pole lug and the second pole lug both extend out of the packaging bag along a first direction,

the electrode assembly formed by winding has a flat part and a bent part, and the battery cell further comprises a buffer member which is positioned between a first surface and the packaging bag, wherein the first surface is a surface of the outermost circle of the bent part close to the packaging bag, and the first surface is arranged in a bent manner and is parallel to the first direction;

wherein an outermost circle of the bending portion is a circle of the bending portion away from a central axis of the electrode assembly, wherein the central axis of the electrode assembly is parallel to the first direction;

the battery cell further comprises a bonding piece, and the bonding piece bonds the winding tail end of the electrode assembly and the electrode assembly body.

2. The battery cell of claim 1, wherein the buffer member is disposed in a curved manner, and the buffer member covers the first surface.

3. The cell of claim 1, wherein,

the outermost circle of the bending part is provided with a second surface, the second surface is arranged in a bending way, and the second surface is parallel to the first direction;

the cell also includes a guard positioned between the second surface and the central axis of the electrode assembly.

4. The cell of claim 3, wherein the protective member is disposed in a curved configuration and covers the second surface.

5. The battery cell of claim 3, wherein the outermost circle of the bending portion is a portion of the outermost circle of the first pole piece, and a portion of the outermost circle of the first pole piece located at the outermost circle of the bending portion includes a first current collector and a first active material, the first active material is disposed on the first current collector, and the protection member has lithium ion permeability.

6. The electrical core according to any of claims 1 to 5, wherein the buffer is provided with an extension that extends in the second direction to the flat portion.

7. The cell of claim 6, wherein the second direction is parallel to the flat portion, and the extension has a length in the second direction that is greater than 5 millimeters.

8. The battery cell of claim 7, wherein the first tab is connected to a portion of the first pole piece located at the flat portion, the second tab is connected to a portion of the second pole piece located at the flat portion, and in the second direction, the extending portion has a gap with one end of the first tab or the second pole piece near the extending portion.

9. The electrical core of any of claims 1 to 5, wherein the buffer is bonded to the pouch.

10. The battery cell according to any one of claims 1 to 5, wherein the number of the curved portions is two, the two curved portions are located on two sides of the flat portion, the number of the buffer members is two, and one buffer member is disposed on one curved portion.

11. A battery pack comprising a cell according to any of claims 1 to 10.

12. An electrical device comprising a load and the battery pack of claim 11, the load being connected to the battery pack.