Battery cell and electronic device using the same

Abstract

A battery cell includes an electrode assembly, comprising: a first electrode sheet including a first current collector and a first active material layer disposed on the surface of the first current collector, the first current collector further including a first empty foil region without the first active material layer; a second electrode sheet; and a separator disposed between the first electrode sheet and the second electrode sheet; the electrode assembly is formed by sequentially winding the first electrode sheet, the separator, and the second electrode sheet; in the winding direction of the electrode assembly, each layer from the second layer to the next outermost layer of the first electrode sheet includes a first flat section, a first bent section and a second bent section respectively disposed on both sides of the first flat section, the first bent section and the second bent section being the bent portions on both sides of each layer of the first electrode sheet; the first empty foil region is disposed in the first flat section, the two sides of the first empty foil region being connected to the first bent section and the second bent section respectively; and in the length direction of the electrode assembly, the first empty foil region does not have the first active material layer. An electrical device includes the battery cell.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more particularly to a battery cell and an electronic device using the battery cell. Background Technology

[0002] With the commercialization of lithium-ion batteries, the market has increasingly higher requirements for the charging speed, temperature rise during charging and discharging, energy density, and rate discharge performance of battery cells. As a result, battery cells with tabs in the middle have emerged.

[0003] However, currently common electrode-centered cells mainly adopt the following structures: One type involves setting electrode grooves in the active material layer of the electrode to expose blank current collectors, fixing the electrode in the electrode grooves. However, in cells with a width of less than 30mm, there is a problem of overlapping electrode grooves between the anode and cathode. Overlapping electrode grooves will cause inconsistent cell thickness, and the problem of lithium plating in the grooves will further worsen the cycle life, resulting in poor performance such as cycle remaining capacity or cycle expansion. Another type involves creating electrode grooves on the electrode sheet, but in the width direction of the electrode sheet, the width of the electrode groove is slightly larger than the short groove at the electrode fixing end. This groove is prone to lithium plating. At the same time, this area without active material coating will cause lithium plating in the area on the cathode electrode sheet corresponding to the anode electrode groove. To prevent lithium plating in this area, insulating adhesive needs to be applied to the cathode electrode sheet corresponding to the anode electrode groove to prevent lithium ion extraction. There are generally at least two layers of protective adhesive paper at the anode electrode position, which increases the cell thickness.

[0004] How to solve the above problems is something that those skilled in the art need to consider. Summary of the Invention

[0005] To address the issues of lithium plating, uneven cell thickness, and low energy density caused by the tab groove design in existing technologies.

[0006] This application provides a battery cell including an electrode assembly. The electrode assembly includes: a first electrode, including a first current collector and a first active material layer disposed on the surface of the first current collector, the first current collector further including a first empty foil area without the first active material layer; a second electrode, including a second current collector and a second active material layer disposed on the surface of the second current collector, the second current collector further including a second empty foil area without the second active material layer; and a separator disposed between the first electrode and the second electrode. The electrode assembly is formed by sequentially winding the first electrode, the separator, and the second electrode. In the winding direction of the electrode assembly, each layer from the second layer to the next outermost layer of the first electrode includes a first flat section, a first bent section and a second bent section respectively disposed on both sides of the first flat section, the first bent section and the second bent section being the bent portions on both sides of each layer of the first electrode, the first empty foil area being disposed on the first flat section, the two sides of the first empty foil area being connected to the first bent section and the second bent section respectively, and in the length direction of the electrode assembly, the first empty foil area is not provided with the first active material layer.

[0007] In one possible implementation, in the winding direction of the electrode assembly, each layer of the second electrode sheet from the second layer to the next outermost layer includes a second flat section, a third bending section and a fourth bending section respectively disposed on both sides of the second flat section, wherein the third bending section and the fourth bending section are the portions where the two sides of each layer of the second electrode sheet are bent, the second empty foil area is disposed in the second flat section, and the two sides of the second empty foil area are respectively connected to the third bending section and the fourth bending section, and in the length direction of the electrode assembly, the second empty foil area is not provided with the second active material layer.

[0008] In one possible implementation, the first current collector has the first active material layer disposed on the other surface opposite to the first empty foil area; or the second current collector has the second active material layer disposed on the other surface opposite to the second empty foil area.

[0009] In one possible implementation, in the width direction of the electrode assembly, the distance between the central symmetry line of the first empty foil area or the second empty foil area and the central symmetry line of the electrode assembly is less than or equal to 2 mm.

[0010] In one possible implementation, the first empty foil area is disposed opposite to the second empty foil area.

[0011] In one possible implementation, in the width direction of the electrode assembly, the two sides of the first empty foil area extend 0-4 mm beyond the width of the second empty foil area and the corresponding sides of the first empty foil area.

[0012] In one possible implementation, the electrode assembly further includes a first tab electrically connected to the first empty foil region, a second tab electrically connected to the second empty foil region, a first insulating layer, and a second insulating layer, wherein the first insulating layer is disposed in the first empty foil region and the second insulating layer is disposed in the second empty foil region.

[0013] In one possible implementation, the first electrode tab is fixed to the first empty foil area by welding, and the first insulating layer covers the surface of the first electrode tab; or, the second electrode tab is fixed to the second empty foil area by welding, and the second insulating layer covers the surface of the second electrode tab.

[0014] In one possible implementation, the first active material layer is disposed on the two surfaces of the winding start section of the first current collector, and the second active material layer is disposed on the two surfaces of the winding end section of the second current collector.

[0015] In one possible implementation, the winding start section of the second current collector includes a fifth bending section, which does not overlap with the winding start section of the first current collector in the thickness direction of the electrode assembly.

[0016] In one possible implementation, the surfaces of the first bending segment and the second bending segment are provided with the first active material layer.

[0017] In one possible implementation, the first bending segment and the second bending segment extending from the surface of the first empty foil area are not provided with the first active material layer.

[0018] In one possible implementation, the first flat segment of the first electrode adjacent to the first empty foil region is provided with the first active material layer.

[0019] An embodiment of this application also provides an electrical device, which includes a working module and a battery, wherein the battery provides electrical energy to the working module and the battery includes the aforementioned battery cells.

[0020] Compared to existing technologies, the battery cell of this application, on the one hand, avoids uneven cell thickness and reduces the risk of lithium plating by placing the tabs and the empty foil area for placing the tabs on the flat section of the battery cell, that is, the tabs and the empty foil area for placing the tabs are not placed on the winding section of the battery cell; on the other hand, the empty foil area for placing the tabs is a single-sided structure, and only a layer of insulating adhesive is attached to the empty foil area to cover the burrs on the current collector to reduce the risk of short circuit. Moreover, reducing the number of insulating adhesive layers can reduce the cell thickness, and the active material layer is provided on the back of the empty foil area where the tabs are placed to increase the energy density of the battery cell. Attached Figure Description

[0021] Figure 1 A schematic diagram of the battery cell structure is provided for one embodiment of this application.

[0022] Figure 2 This is a partially enlarged schematic diagram of the first empty foil area of ​​a battery cell provided in an embodiment of this application.

[0023] Figure 3 This is a partially enlarged schematic diagram of the second empty foil region of a battery cell provided in an embodiment of this application.

[0024] Figure 4 This is a plan view of the front and back sides of the first empty foil area of ​​a battery cell provided in an embodiment of this application.

[0025] Figure 5 This is a plan view of the front and back sides of the second empty foil area of ​​a battery cell provided in an embodiment of this application.

[0026] Figure 6 This is a partially enlarged schematic diagram of the first empty foil area of ​​a battery cell provided in another embodiment of this application.

[0027] Figure 7 This is a partially enlarged schematic diagram of the second empty foil region of a battery cell provided in another embodiment of this application.

[0028] Figure 8 This is a partially enlarged schematic diagram of the first empty foil area of ​​a battery cell provided in another embodiment of this application.

[0029] Figure 9 This is a partially enlarged schematic diagram of the second empty foil region of a battery cell provided in another embodiment of this application.

[0030] Figure 10 This is a schematic diagram of an electronic device according to an embodiment of this application.

[0031] Explanation of main component symbols Cell 1 Electrode assembly 10 First Polar Film 11 First empty foil area 110 First current collector 111 First active material layer 112 First flat section 113 First bend section 114 Second bend section 115 Second electrode 12 Second empty foil area 120 Second current collector 121 Fifth bend segment 1210 Third empty foil area 1211 Second active material layer 122 Second flat section 123 Third bend section 124 Fourth bend section 125 Diaphragm 13 First Pole Ear 15 Second pole ear 16 First insulating layer 17 Second insulating layer 18 Electronic devices 100 Working Module 101 Battery 102 The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0032] The following description will refer to the accompanying drawings to provide a more complete picture of the present application. The drawings illustrate exemplary embodiments of the present application. However, the present application may be implemented in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. These exemplary embodiments are provided to make the present application thorough and complete, and to fully convey the scope of the present application to those skilled in the art. Similar reference numerals denote the same or similar components.

[0033] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to limit the application. As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” are intended to also include the plural forms. Furthermore, when used herein, “comprising” and / or “including” and / or “having,” integers, steps, operations, components, and / or components, but does not exclude the presence or addition of one or more other features, regions, integers, steps, operations, components, components, and / or groups thereof.

[0034] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. Furthermore, unless expressly defined herein, terms such as those defined in a general dictionary should be interpreted as having the same meaning as they have in the relevant art and in the content of this application, and will not be interpreted as having an idealized or overly formal meaning.

[0035] The following description, in conjunction with the accompanying drawings, illustrates exemplary embodiments. It should be noted that components depicted in the drawings are not necessarily shown to scale; and identical or similar components will be designated with the same or similar reference numerals or similar technical terms.

[0036] The specific embodiments of this application will be further described in detail below with reference to the accompanying drawings.

[0037] Figure 1 A schematic diagram of the structure of cell 1 is provided for an embodiment of this application; Figure 2 A partially enlarged schematic diagram of the first empty foil region 110 of the battery cell 1 provided in an embodiment of this application; Figure 3 This is a partially enlarged schematic diagram of the second empty foil region 120 of the battery cell 1 provided in an embodiment of this application.

[0038] The battery cell 1 includes an electrode assembly 10, which includes a first electrode 11, a second electrode 12, and a separator 13. The first electrode 11 includes a first current collector 111 and a first active material layer 112 disposed on the surface of the first current collector 111. The first current collector 111 also includes a first empty foil region 110 without the first active material layer 112. The second electrode 12 includes a second current collector 121 and a second active material layer 122 disposed on the surface of the second current collector 121. The second current collector 121 also includes a second empty foil region 120 without the second active material layer 122. The separator 13 is disposed between the first electrode 11 and the second electrode 12.

[0039] The electrode assembly 10 is formed by sequentially stacking and winding a first electrode 11, a diaphragm 13, and a second electrode 12.

[0040] In one embodiment, during the winding process, the first electrode 11 and the second electrode 12 are spaced apart, and a diaphragm 13 is disposed between the first electrode 11 and the second electrode 12 to insulate the first electrode 11 and the second electrode 12 from contact and short circuit.

[0041] In the winding direction of the electrode assembly 10, each layer of the second to the outermost layer of the first electrode 11 includes a first flat section 113, a first bent section 114 and a second bent section 115 respectively disposed on both sides of the first flat section 113. The first bent section 114 and the second bent section 115 are the bent portions on both sides of each layer of the first electrode 11. A first empty foil area 110 is disposed in the first flat section 113. The two sides of the first empty foil area 110 are connected to the first bent section 114 and the second bent section 115 respectively. In the length direction of the electrode assembly 10, the first empty foil area 110 does not have a first active material layer 112.

[0042] In one embodiment, each of the second to the outermost layers of the first electrode 11 includes a first flat section 113, which is the portion of the cell 1 that extends horizontally during winding and does not bend due to winding. The first bending section 114 and the second bending section 115 respectively disposed on both sides of the first flat section 113 are the portions of the first electrode 11 that bend during winding to achieve winding of the cell 1. The thickness of the first electrode 11 at the first empty foil area 110 is less than the thickness of the first electrode 11 adjacent to the first empty foil area 110. By placing the first empty foil area 110 at the first flat section 113, the thinner portion of the first electrode 11 can be prevented from extending into the winding bending area, thus avoiding uneven thickness of the cell 1.

[0043] In one embodiment, a first empty foil region 110 is disposed on at least one first flat segment 113, and the two sides of the first empty foil region 110 can be connected to a first bent segment 114 and a second bent segment 115 respectively, so that the first empty foil region 110 can occupy a first flat segment 113. In other embodiments, the surfaces of the first bent segment 114 and the second bent segment 115 are provided with a first active material layer 112; the first bent segment 114 and the second bent segment 115 extending from the surface of the first empty foil region 110 are not provided with the first active material layer 112. In other embodiments, the first flat segment 113 of the first electrode 11 adjacent to the first empty foil region 110 is provided with the first active material layer 112.

[0044] In the winding direction of the electrode assembly 10, each layer of the second to the outermost layer of the second electrode 12 includes a second flat section 123, a third bending section 124 and a fourth bending section 125 respectively disposed on both sides of the second flat section 123. The third bending section 124 and the fourth bending section 125 are the bending portions on both sides of each layer of the second electrode 12. The second empty foil area 120 is disposed in the second flat section 123. The two sides of the second empty foil area 120 are connected to the third bending section 124 and the fourth bending section 125 respectively. In the length direction of the electrode assembly 10, the second empty foil area 120 does not have a second active material layer 122.

[0045] In one embodiment, each of the second to the next outermost layers of the second electrode 12 includes a second flat section 123, which is the portion of the cell 1 that extends horizontally during winding and does not bend due to winding. The third bending section 124 and the fourth bending section 125, respectively disposed on both sides of the second flat section 123, are the portions of the second electrode 12 that bend during winding of the cell 1 to achieve winding of the cell 1. The thickness of the second electrode 12 at the second empty foil area 120 is less than the thickness of the second electrode 12 adjacent to the second empty foil area 120. By placing the second empty foil area 120 at the second flat section 123, the thinner portion of the second electrode 12 can be prevented from extending into the winding bending area, thus avoiding uneven thickness of the cell 1.

[0046] In one embodiment, a second empty foil region 120 is disposed on at least one second flat segment 123, and both sides of the second empty foil region 120 can be connected to a third bent segment 124 and a fourth bent segment 125 respectively, so that the second empty foil region 120 can occupy a second flat segment 123. In other embodiments, the surfaces of the third bent segment 124 and the fourth bent segment 125 are provided with a second active material layer 122; the third bent segment 124 and the fourth bent segment 125 extending from the surface of the second empty foil region 120 are not provided with a second active material layer 122. In other embodiments, the second flat segment 123 of the second electrode 12 adjacent to the second empty foil region 120 is provided with a second active material layer 122.

[0047] The first empty foil region 110 and the second empty foil region 120 are arranged opposite to each other. In one embodiment, the first empty foil region 110 and the second empty foil region 120 are respectively disposed on adjacent first electrode 11 and second electrode 12. The first empty foil region 110 is disposed facing the second empty foil region 120, and the second empty foil region 120 is disposed facing the first empty foil region 110. This makes the first empty foil region 110 without the first active material layer 112 correspond to the second empty foil region 120 without the second active material layer 122, thus avoiding uneven cell thickness and lithium plating problems caused by misalignment.

[0048] In one embodiment, in the width direction of the electrode assembly 10, the distance between the central symmetry line of the first empty foil area 110 or the second empty foil area 120 and the central symmetry line of the electrode assembly 10 is less than or equal to 2 mm. That is, the first empty foil area 110 and the second empty foil area 120 are located in the middle region of the cell 1, thereby improving the flatness of the cell 1.

[0049] In the width direction of the electrode assembly 10, the two sides of the first empty foil area 110 extend beyond the corresponding sides of the second empty foil area 120 by 0 to 4 mm. In one embodiment, the first electrode 11 can be the cathode of the battery cell 1, and the second electrode 12 can be the anode of the battery cell 1. The fact that the two sides of the first empty foil area 110 extend beyond the corresponding sides of the second empty foil area 120 can prevent lithium plating on the electrode and improve the safety performance of the battery cell 1.

[0050] like Figure 4 and Figure 5 As shown, Figure 4 A plan view of the front and back sides of the first empty foil area 110 of the battery cell 1 provided in the embodiments of this application; Figure 5 This is a plan view of the front and back sides of the second empty foil area 120 of the battery cell 1 provided in the embodiments of this application.

[0051] The first current collector 111 has a first active material layer 112 on the surface opposite to the first empty foil area 110; the second current collector 121 has a second active material layer 122 on the surface opposite to the second empty foil area 120. In one embodiment, a first active material layer 112 and a second active material layer 122 are respectively disposed on the back side of the first empty foil area 110 and the second empty foil area 120. That is, the first empty foil area 110 and the second empty foil area 120 are disposed on one side, so that the thickness of the first electrode 11 where the first empty foil area 110 is disposed and the thickness of the second electrode 12 where the second empty foil area 120 is disposed have less impact on the overall thickness uniformity of the battery cell 1 when winding or stacking compared with the thickness of the empty foil area with traditional double-sided slotting. Moreover, the first active material layer 112 is disposed on the back side of the first electrode 11 corresponding to the first empty foil area 110, and the second active material layer 122 is disposed on the back side of the second electrode 12 corresponding to the second empty foil area 120, which increases the total amount of active material in the battery cell 1 and further improves the energy density of the battery cell 1 without changing the volume.

[0052] In one embodiment, the first empty foil region 110 does not have a first active material layer 112 in the length direction of the electrode assembly 10, and the second empty foil region 120 does not have a second active material layer 122 in the length direction of the electrode assembly 10. That is, the opposite sides of the first empty foil region 110 and the second empty foil region 120 extend to the edges of the first current collector 111 and the second current collector 121, respectively. Both the first empty foil region 110 and the second empty foil region 120 have double-sided openings, providing a complete stress relief window for the expansion of the first electrode 11 and the second electrode 12 in the electrochemical cycle.

[0053] The electrode assembly 10 further includes a first tab 15 electrically connected to a first empty foil region 110, a second tab 16 electrically connected to a second empty foil region 120, a first insulating layer 17, and a second insulating layer 18. The first insulating layer 17 is disposed in the first empty foil region 110, and the second insulating layer 18 is disposed in the second empty foil region 120. The first tab 15 is fixed to the first empty foil region 110 by welding, and the first insulating layer 17 at least covers the surface of the first tab 15; the second tab 16 is fixed to the second empty foil region 120 by welding, and the second insulating layer 18 at least covers the surface of the second tab 16.

[0054] In one embodiment, the first current collector 111 and the second current collector 121 can be made of materials with good conductivity and ductility, such as copper foil and aluminum foil. The first tab 15 can be fixed to the first current collector 111 and electrically connected by means of resistance welding, ultrasonic welding, laser welding, conductive adhesive bonding, etc. The second tab 16 can also be fixed to the first current collector 111 and electrically connected by means of resistance welding, ultrasonic welding, laser welding, conductive adhesive bonding, etc. The first insulating layer 17 is disposed in the first empty foil area 110 and at least covers the first tab 15 and the connection area between the first tab 15 and the first current collector 111, so as to at least cover the burrs that may be generated when the first tab 15 and the first current collector 111 are connected, and avoid short circuit of the battery cell 1. The second insulating layer 18 is disposed in the second empty foil area 120 and at least covers the second tab 16 and the connection area between the second tab 16 and the second current collector 121, so as to at least cover the burrs that may be generated when the second tab 16 and the second current collector 121 are connected, and avoid short circuit of the battery cell 1.

[0055] In this embodiment, as Figure 2 and Figure 3 As shown, the first insulating layer 17 may only cover the first tab 15 and the welding area between the first tab 15 and the first current collector 111; the second insulating layer 18 may only cover the second tab 16 and the welding area between the second tab 16 and the second current collector 121.

[0056] In other embodiments, such as Figure 6 and Figure 7 As shown, the first insulating layer 17 covers the surface of the first tab 15 and the first current collector 111 corresponding to the first empty foil area 110, where the first tab 15 is not provided; the second insulating layer 18 can cover the surface of the second tab 16 and the second current collector 121 corresponding to the second empty foil area 120, where the second tab 16 and the second current collector 121 are not provided.

[0057] In other embodiments, such as Figure 8 and Figure 9As shown, the first insulating layer 17 covers the first empty foil area 110 and the first tab 15, and the two ends of the first insulating layer 17 can overlap the surface of the first active material layer 112 to cover the first empty foil area 110; the second insulating layer 18 covers the second empty foil area 120 and the second tab 16, and the two ends of the second insulating layer 18 can overlap the surface of the second active material layer 122 to cover the second empty foil area 120.

[0058] In one embodiment, the two surfaces of the winding start section of the first current collector 111 are respectively provided with a first active material layer 112, and the two surfaces of the winding end section of the second current collector 121 are respectively provided with a second active material layer 122.

[0059] In one embodiment, the winding start section of the second current collector 121 includes a fifth bending section 1210, which does not overlap with the winding start section of the first current collector 111 in the thickness direction of the electrode assembly 10.

[0060] In one embodiment, the winding start section of the second electrode 12 may include a third empty foil area 1211, which is connected to a fifth bending section 1210. The fifth bending section 1210 can be a pre-folded structure and is further connected to the flat section of the second electrode 12. The fifth bending section 1210 may be oriented towards the winding center of the cell 1. The length of the third empty foil area 1211 may be less than half the width of the core. In the thickness direction of the electrode assembly 10, the fifth bending section 1210 does not overlap with the winding start section of the first current collector 111 to prevent folding on one side of the first electrode 11. Furthermore, the pre-folded fifth bending section 1210 can be used to compensate for thickness differences in the cell 1, making the cell 1 more even in thickness.

[0061] like Figure 10 The diagram shown is a schematic of an electronic device 100 provided in an embodiment of this application. This application also provides an electronic device 100, which includes a working module 101 and a battery 102. The battery 102 provides electrical energy to the working module 101 and includes the aforementioned battery cell 1. Figure 10 In this example, the electronic device 100 is a mobile phone. In other embodiments, the electronic device 100 may also be a personal computer, smart home appliance, industrial controller, electric vehicle, hybrid electric vehicle, etc.

[0062] The specific embodiments of this application have been described above with reference to the accompanying drawings. However, those skilled in the art will understand that various changes and substitutions can be made to the specific embodiments of this application without departing from the spirit and scope of this application. All such changes and substitutions fall within the scope defined by this application.

Claims

1. A battery cell, comprising an electrode assembly, the electrode assembly comprising: The first electrode includes a first current collector and a first active material layer disposed on the surface of the first current collector. The first current collector also includes a first empty foil area where the first active material layer is not disposed. The second electrode includes a second current collector and a second active material layer disposed on the surface of the second current collector; A first electrode tab is disposed in the first empty foil area and electrically connected to the first empty foil area; A diaphragm is disposed between the first electrode and the second electrode; and The electrode assembly is formed by sequentially winding the first electrode, the diaphragm, and the second electrode, characterized in that: In the winding direction of the electrode assembly, each of the second to the outermost layers of the first electrode sheet includes a first flat section, a first bent section and a second bent section respectively disposed on both sides of the first flat section, wherein the first bent section and the second bent section are the portions on both sides of each layer of the first electrode sheet that are bent; the first empty foil area is disposed on at least one of the first flat sections, the first tab is located on the first flat section, and the first empty foil area does not extend to the first bent section and the second bent section on at least one side in the winding direction of the electrode assembly.

2. The battery cell as described in claim 1, characterized in that, The electrode assembly further includes a second tab, and the second current collector further includes a second empty foil region without the second active material layer. The second tab is disposed in the second empty foil region and electrically connected to the second empty foil region. In the winding direction of the electrode assembly, each layer of the second electrode sheet from the second layer to the next outermost layer includes a second flat section, a third bending section and a fourth bending section respectively disposed on both sides of the second flat section, wherein the third bending section and the fourth bending section are the portions where the two sides of each layer of the second electrode sheet are bent. The second empty foil region is disposed on at least one of the second flat sections, the second tab is located on the second flat section, and the second empty foil region does not extend to the first bending section and the second bending section on at least one side in the winding direction of the electrode assembly.

3. The battery cell as described in claim 1, characterized in that, The first current collector has the first active material layer disposed on the other surface opposite to the first empty foil area; or, the second current collector further includes a second empty foil area without the second active material layer disposed thereon; the second current collector has the second active material layer disposed on the other surface opposite to the second empty foil area.

4. The battery cell as described in claim 1, characterized in that, The second current collector also includes a second empty foil region where the second active material layer is not provided; in the width direction of the electrode assembly, the distance between the central symmetry line of the first empty foil region or the second empty foil region and the central symmetry line of the electrode assembly is less than or equal to 2 mm.

5. The battery cell as described in claim 1, characterized in that, The second current collector also includes a second empty foil region where the second active material layer is not provided; the first empty foil region is disposed opposite to the second empty foil region.

6. The battery cell as described in claim 5, characterized in that, The second current collector also includes a second empty foil region where the second active material layer is not provided; in the width direction of the electrode assembly, the width of the first empty foil region on both sides of the first empty foil region exceeds the width of the second empty foil region on the corresponding sides of the first empty foil region by 0 to 4 mm.

7. The battery cell as described in claim 1, characterized in that, The electrode assembly further includes a first insulating layer disposed in the first empty foil area.

8. The battery cell as described in claim 7, characterized in that, The first electrode tab is fixed to the first empty foil area by welding, and the first insulating layer covers the surface of the first electrode tab.

9. The battery cell as described in claim 8, characterized in that, The first insulating layer covers the first empty foil area.

10. The battery cell as described in claim 1, characterized in that, The second current collector also includes a second empty foil region where the second active material layer is not disposed; the electrode assembly also includes a second tab and a second insulating layer, the second tab being disposed in the second empty foil region and electrically connected to the second empty foil region; the second insulating layer being disposed in the second empty foil region.

11. The battery cell as described in claim 10, characterized in that, The second electrode tab is fixed to the second empty foil area by welding, and the second insulating layer covers the surface of the second electrode tab.

12. The battery cell as described in claim 11, characterized in that, The second insulating layer covers the second empty foil area.

13. The battery cell as described in claim 1, characterized in that, The first active material layer is disposed on the two surfaces of the winding start section of the first current collector, and the second active material layer is disposed on the two surfaces of the winding end section of the second current collector.

14. The battery cell as described in claim 1, characterized in that, The second current collector has a winding start section including a fifth bending section, which does not overlap with the winding start section of the first current collector in the thickness direction of the electrode assembly.

15. The battery cell as described in claim 1, characterized in that, The first bending segment and the second bending segment are provided with the first active material layer on their surfaces.

16. The battery cell as described in claim 11, characterized in that, The first and second bending sections, which extend from the surface of the first empty foil area, do not have the first active material layer disposed thereon.

17. The battery cell as described in claim 1, characterized in that, The first flat section of the first electrode adjacent to the first empty foil region is provided with the first active material layer.

18. The battery cell as described in claim 1, characterized in that, The width of the electrode assembly is less than 30 mm.

19. An electrical appliance, characterized in that, The electrical device includes a working module and a battery, the battery providing power to the working module, and the battery including the battery cells as described in any one of claims 1 to 17.

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