Battery monomer, battery and electric equipment

Abstract

The utility model relates to the technical field of batteries, and provides a battery monomer, a battery and electric equipment. The battery cell is formed by winding a positive plate, a diaphragm and a negative plate, the shell is used for accommodating the battery cell, the negative plate comprises a first negative current collector and a second negative current collector which are sequentially connected along the winding direction, the first negative current collector is provided with a negative active material layer, and the second negative current collector is positioned on the outermost layer of the battery cell; and the motor is electrically connected with the shell. By configuring the second negative current collector to be electrically connected with the shell, on one hand, the contact area of the negative plate and the shell is increased, and on the other hand, the current flowing path is increased, so that the conductivity and the heat dissipation capability of the battery cell can be effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a battery monomer, a battery and an electrical device. Background Art

[0002] At present, battery cells include battery cells with tabs on the same side and battery cells with tabs on different sides. In battery cells with tabs on different sides, the positive tab and the negative tab are located on the two sides of the battery cell respectively, and in battery cells with tabs on the same side, the positive tab and the negative tab are located on the same side of the battery cell. Whether it is a battery cell with tabs on the same side or a battery cell with tabs on different sides, generally, the positive tab is electrically connected to the pole, and the negative tab is electrically connected to the shell of the battery cell. In these existing battery cells, since the contact area between the negative tab and the shell is small, it is not conducive to the heat dissipation of the battery cell, thereby reducing the performance, life and safety of the battery cell. Utility Model Content

[0003] The utility model aims to provide a battery cell, a battery and an electrical device, aiming to solve the technical problem of low heat dissipation capacity of the existing battery cell.

[0004] In the first aspect, the present application provides a battery cell, including a battery cell formed by winding a positive electrode sheet, a separator and a negative electrode sheet, and a shell for accommodating the battery cell, the negative electrode sheet includes a first negative electrode collector and a second negative electrode collector connected in sequence along the winding direction, the first negative electrode collector is provided with a negative electrode active material layer, and the second negative electrode collector is located at the outermost layer of the battery cell and is electrically connected to the shell.

[0005] Optionally, a connecting portion is provided at one end of the second negative electrode current collector away from the first negative electrode current collector, and the second negative electrode current collector is connected to the shell through the connecting portion.

[0006] Optionally, the outer surface of the connecting portion is provided with conductive adhesive, and the conductive adhesive is bonded to the shell.

[0007] Optionally, the connecting portion is welded to the shell.

[0008] Optionally, along the winding direction of the battery cell, a finishing glue is provided on the outer surface of the battery cell, and the second negative electrode current collector is provided with at least one avoidance groove for the finishing glue to pass through, the avoidance groove runs through the two surfaces of the second negative electrode current collector in its own thickness direction, and one end of the finishing glue is bonded to the first negative electrode current collector, or one end of the finishing glue is bonded to an end of the second negative electrode current collector close to the first negative electrode current collector.

[0009] Optionally, in the unfolded state of the negative electrode sheet, in the length direction of the negative electrode sheet, the projection of the first negative electrode current collector at least partially overlaps with the projection of the avoidance groove.

[0010] Optionally, two avoidance grooves are provided, and the two avoidance grooves are respectively located at two ends of the second negative electrode current collector in the height direction of the battery cell.

[0011] Optionally, the two avoidance grooves extend to two side surfaces of the second negative electrode current collector in the height direction respectively.

[0012] Optionally, the avoidance groove extends to the connection between the first negative electrode current collector and the second negative electrode current collector.

[0013] Optionally, the avoidance groove extends to a surface of the second negative electrode current collector away from the first negative electrode current collector.

[0014] Optionally, the second negative electrode current collector is wound around the battery cell for at most five turns.

[0015] In a second aspect, the present application provides a battery, comprising the above-mentioned battery cell

[0016] In a third aspect, the present application provides an electrical device comprising the above-mentioned battery cell or battery.

[0017] The battery cell provided by the utility model has the following beneficial effects: in the unfolded state of the negative electrode sheet, the first negative electrode current collector is provided with a second negative electrode current collector on one side in its length direction. When the battery cell is formed, the second negative electrode current collector is formed on the outermost layer of the battery cell as the winding end of the negative electrode sheet. By configuring the second negative electrode current collector to be electrically connected to the shell, on the one hand, the contact area between the negative electrode sheet and the shell is increased, and on the other hand, the flow path of the current is increased, which can effectively improve the conductivity and heat dissipation capacity of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0019] Figure 1 A schematic diagram of the structure of a battery cell provided in an embodiment of the utility model;

[0020] Figure 2 A schematic diagram of the structure of a battery cell provided by an embodiment of the utility model;

[0021] Figure 3 A schematic diagram of the structure of a negative electrode sheet (in an unfolded state) provided in an embodiment of the utility model;

[0022] Figure 4 Another structural schematic diagram of a negative electrode sheet (in unfolded state) provided in an embodiment of the utility model;

[0023] Figure 5 Another structural schematic diagram of a battery cell provided in an embodiment of the utility model;

[0024] Figure 6 Another structural schematic diagram of a battery cell provided by an embodiment of the utility model;

[0025] Figure 7 Another structural schematic diagram of a negative electrode sheet (in unfolded state) provided in an embodiment of the utility model;

[0026] Figure 8 Another structural schematic diagram of a negative electrode sheet (in unfolded state) provided in an embodiment of the utility model;

[0027] Fig. 9 Another structural schematic diagram of a negative electrode sheet (in unfolded state) provided in an embodiment of the utility model;

[0028] Fig.10 Another structural schematic diagram of the negative electrode sheet (in unfolded state) provided in an embodiment of the utility model.

[0029] Among them, the reference numerals in the figure are:

[0030] 100, battery cell; 10, negative electrode sheet; 20, positive electrode sheet;

[0031] 30. diaphragm; 40. battery cell; 50. housing;

[0032] 60. Finishing glue; 11. First negative electrode current collector; 12. Second negative electrode current collector;

[0033] 111, negative electrode active material layer; 112, negative electrode ear; 121, conductive glue;

[0034] 122. Avoidance groove; 21. Positive ear; 61. Fixing place. DETAILED DESCRIPTION

[0035] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0036] Reference throughout the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Thus, when the phrases "in one embodiment" or "in some embodiments" appear in various places throughout the specification, not all references are to the same embodiment. Furthermore, in one or more embodiments, the particular features, structures, or characteristics may be combined in any suitable manner.

[0037] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0038] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0039] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] Please refer to Figures 1 to 10 Now, the battery cell 100, the battery and the electrical equipment in the embodiment of the utility model are described.

[0041] Please refer to Figure 3 and Figure 4 , wherein the X-axis direction is the length direction of the negative electrode sheet 10 in the unfolded state, the Y-axis direction is the width direction of the negative electrode sheet 10 in the unfolded state, and the Z-axis direction is the thickness direction of the negative electrode sheet 10 in the unfolded state.

[0042] For battery cells with tabs on the same side, during long-term charging and discharging, the overcurrent area of ​​the battery cell 40 is concentrated, and the heat dissipation capacity of the battery cell is low, resulting in excessive internal heat of the battery cell, thereby reducing the performance, service life and safety of the battery cell.

[0043] To do this, refer to Figures 1 to 3 The present application provides a battery cell 100, which includes a battery cell 40 formed by winding a positive electrode sheet 20, a separator 30 and a negative electrode sheet 10, and a shell 50 for accommodating the battery cell 40, the negative electrode sheet 10 includes a first negative electrode collector 11 and a second negative electrode collector 12 connected in sequence along the winding direction, the first negative electrode collector 11 is provided with a negative electrode active material layer 111, the second negative electrode collector 12 is located at the outermost layer of the battery cell 40, and is electrically connected to the shell 50.

[0044] In the unfolded state of the negative electrode sheet 10, that is, the negative electrode sheet 10 is in a straight shape as a whole, the first negative electrode current collector 11 is provided with a second negative electrode current collector 12 on one side in the length direction thereof. When the battery cell 40 is formed, the second negative electrode current collector 12 is formed on the outermost layer of the battery cell 40 as the winding end of the negative electrode sheet 10. By configuring the second negative electrode current collector 12 to be electrically connected to the shell 50, on the one hand, the contact area between the negative electrode sheet 10 and the shell 50 is increased, and on the other hand, the flow path of the current is increased, so that the conductivity and heat dissipation capabilities of the battery cell 40 can be effectively improved.

[0045] In addition, the existing equipment has a large deviation in measuring the internal resistance of the battery cells of the battery cells with the tabs on the same side. The present application can effectively reduce the deviation in measuring the internal resistance of the battery cells of the battery cells with the tabs on the same side by adding a current flow path, that is, the negative electrode sheet 10 is electrically connected to the shell 50.

[0046] It is understandable that the first negative electrode current collector 11 and the second negative electrode current collector 12 may be metal foil or composite current collectors, and the material of the metal foil may be, for example, copper, nickel, titanium, silver, nickel-copper alloy, etc. The first negative electrode current collector 11 and the second negative electrode current collector 12 may be the same or different, which is not limited here. In this embodiment, the first negative electrode current collector 11 and the second negative electrode current collector 12 are made of the same material, which can reduce the difficulty of producing the negative electrode sheet 10.

[0047] The battery cell 100 provided in the present application can be not only a battery cell with tabs on the same side, but also a battery cell with tabs on the opposite sides. The present application is described using a battery cell with tabs on the same side.

[0048] In another embodiment of the present application, the positive electrode sheet 20 includes a positive electrode current collector and a positive electrode active material layer. The positive electrode current collector is coated with the above-mentioned positive electrode active material layer on both sides in its thickness direction, and a plurality of spaced positive electrode ears 21 are arranged on one side in its width direction. Please refer to Figures 4 to 6, the first negative current collector 11 is coated with a negative active material layer 111 on both sides in the thickness direction, and the first negative current collector 11 is provided with a plurality of spaced negative tabs 112 on one side in the width direction. The negative electrode sheet 10, the separator 30 and the positive electrode sheet 20 are wound by a winding device. After the battery cell 40 is formed, the positive tab 21 and the negative tab 112 are both located on the same side of the battery cell 40, and the two are flush with one end away from the battery cell 40, so as to facilitate welding with the current collector. All positive tabs 21 form a positive tab group, and all negative tabs 112 form a negative tab group. The shape of the positive tab group and the shape of the negative tab group are both fan-shaped, and the positive tab group and the negative tab group are symmetrically distributed about the axis of the battery cell 40. In this way, the risk of short circuit of the battery cell 40 caused by the short distance between the positive tab 21 and the negative tab 112 can be reduced.

[0049] In another embodiment of the present application, illustratively, the length of the positive electrode sheet 20 is 4.5 to 7 m, and the length of the positive electrode active material layer is 4.5 to 7 m. The length of the negative electrode sheet 10 is 4.8 to 7.2 m, and the length of the negative electrode active material layer 111 is 4.6 to 7.1 m. After the battery cell 40 is formed, the second negative electrode current collector 12 is wound around the battery cell 40 up to five times, and preferably, the second negative electrode current collector 12 is wound around the battery cell 40 one to three times. With such a configuration, on the one hand, it can be avoided that the negative electrode sheet 10 is too long as a whole, making it difficult for the battery cell 40 to be loaded into the shell 50. In addition, it can also be avoided that the second negative electrode current collector 12 not coated with the negative electrode active material layer 111 is too long, so as to ensure that the battery cell 100 has a higher energy density. On the other hand, after the battery cell 40 is loaded into the shell 50, there is a gap between the battery cell 40 and the shell 50 for the battery cell 40 to expand. If the second negative electrode current collector 12 is wound around the battery cell 40 at least once, then after the battery cell 40 expands, the inner wall of the shell 50 can contact one circle of the second negative electrode current collector 12, which greatly increases the contact area between the shell 50 and the second negative electrode current collector 12, which is beneficial to improving the current flow capacity of the battery cell 40.

[0050] Of course, in some other embodiments, the second negative electrode current collector 12 may be wound around the battery cell 40 for less than one turn.

[0051] In addition, the length of the separator 30 is 4.7 to 7.2 m, and the separator 30 completely covers the positive electrode sheet 20 to prevent the battery cell 40 from short-circuiting due to the contact between the positive electrode sheet 20 and the negative electrode sheet 10. It is worth mentioning that since the second negative electrode collector 12 is in contact and connected with the shell 50 to form an electrical connection, the separator 30 does not cover or does not completely cover the second negative electrode collector 12, and the winding end of the second negative electrode collector 12 exceeds the winding end of the positive electrode sheet 20 and the separator 30.

[0052] It should be noted that the lengths of the positive electrode sheet 20, the negative electrode sheet 10, and the separator 30 mentioned above are merely exemplary and should not be considered as limitations of the present invention. That is, in some other embodiments, the length of the positive electrode sheet 20 may be greater than 7 m, and the lengths of the negative electrode sheet 10 and the separator 30 need to be adjusted according to the length of the positive electrode sheet 20.

[0053] In another embodiment of the present application, a connection portion is provided at one end of the second negative current collector 12 away from the first negative current collector 11, and the second negative current collector 12 is connected to the shell 50 through the connection portion. In this embodiment, the connection portion is provided at one end of the second negative current collector 12 away from the first negative current collector 11, on the one hand, to avoid affecting the expansion of the battery cell 40, and on the other hand, the outermost layer of the expanded battery cell 40, that is, the second negative current collector 12, will contact the inner wall of the shell 50, so that the area on the second negative current collector 12 except the connection portion can also be energized with the shell 50, therefore, only providing the connection portion at the end of the second negative current collector 12 can improve the production efficiency of the battery cell 100.

[0054] In another embodiment of the present application, please refer to Figure 1 and Figure 3 The outer surface of the connection part is provided with a conductive adhesive 121, and the conductive adhesive 121 is bonded to the housing 50. The surface of the connection part facing the axis of the battery cell 40 is the inner surface, and the surface of the connection part facing away from the axis of the battery cell 40 is the outer surface. The provision of the conductive adhesive 121 can improve the conductive effect between the negative electrode sheet 10 and the housing 50, and can also reduce the difficulty of assembling the battery cell 40 and the housing 50.

[0055] In some embodiments, the conductive adhesive 121 is a mixture of carbon material, polyolefin material, petroleum resin, and conductive agent. Of course, in some other embodiments, the existing conductive adhesive 121 can also be used, which is not limited here.

[0056] The shape of the conductive glue 121 can be a triangle, a rectangle, a polygon or an irregular shape, etc. In this embodiment, the shape of the conductive glue 121 is a rectangle. Exemplarily, the length of the conductive glue 121 is 30 to 70 mm, the width of the conductive glue 121 is 10 to 40 mm, and the thickness of the conductive glue 121 is 0.1 to 0.3 mm. It should be noted that the above parameters are merely exemplary and should not be regarded as limitations on the present application.

[0057] In some embodiments, the connection portion is welded to the shell 50 , and this connection method can effectively improve the stability of the battery cell 40 after being connected to the shell 50 .

[0058] In another embodiment of the present application, please refer to Figures 1 to 3 ,as well as Figures 7 to 10Along the winding direction of the battery cell 40, a finishing glue 60 is provided on the outer surface of the battery cell 40, and the second negative electrode current collector 12 is provided with at least one avoidance groove 122 for the finishing glue 60 to pass through. The avoidance groove 122 runs through the two surfaces of the second negative electrode current collector 12 in its own thickness direction, and one end of the finishing glue 60 is bonded to the first negative electrode current collector 11, or one end of the finishing glue 60 is bonded to one end of the second negative electrode current collector 12 close to the first negative electrode current collector 11.

[0059] In the unfolded state of the second negative electrode current collector 12, that is, the second negative electrode current collector 12 is in a straight shape as a whole, the avoidance groove 122 penetrates the two surfaces of the second negative electrode current collector 12 in its own thickness direction. In the wound state of the second negative electrode current collector 12, the avoidance groove 122 penetrates the inner surface and the outer surface of the second negative electrode current collector 12, wherein the surface of the second negative electrode current collector 12 facing the axis of the battery cell 40 is the inner surface, and the surface of the second negative electrode current collector 12 facing away from the axis of the battery cell 40 is the outer surface.

[0060] The end glue 60 extends along the winding direction of the battery cell 40 and is used to fix the battery cell 40 to prevent the battery cell 40 from spreading. In fact, the end glue 60 will apply a pulling force along the winding direction to the negative electrode sheet 10, and the connecting portion is fixedly connected to the shell 50, so the connecting portion will apply an outward pulling force to the negative electrode sheet 10. It can be understood that the direction away from the axis of the battery cell 40 is outward. By providing an avoidance groove 122 on the second negative electrode collector 12, the fixing part 61 of the end glue 60 is away from the connecting portion in the length direction of the negative electrode sheet 10, thereby preventing the end of the negative electrode sheet 10 from being torn due to two forces in different directions. In addition, if the avoidance groove 122 is not provided, when the battery cell 40 expands, the end of the negative electrode sheet 10 is more likely to crack. The provision of the avoidance groove 122 can enable the second negative electrode collector 12 to be firmly connected to the shell 50 while ensuring the fixing effect of the end glue 60 on the battery cell 40.

[0061] In another embodiment of the present application, please refer to Figure 3 , Figures 7 to 10, in the unfolded state of the negative electrode sheet 10, in the length direction of the negative electrode sheet 10, the projection of the first negative electrode collector 11 and the projection of the avoidance groove 122 at least partially overlap. It can be understood that, generally, in the height direction of the battery cell 40, the height of the negative electrode sheet 10 and the positive electrode sheet 20 are not much different or equal. If the avoidance groove 122 is higher than the first negative electrode collector 11 (that is, the bottom of the avoidance groove 122 is higher than the first negative electrode collector 11), then the tail glue 60 is difficult to stick on the first negative electrode collector 11, the positive electrode sheet 20 or the outer surface of the diaphragm 30, resulting in the battery cell 40 cannot be fixed by the tail glue 60. Of course, the above problem can be solved by extending the height of the positive electrode sheet 20, but doing so will reduce the energy density of the battery cell 100. It can be seen that the technical solution can ensure the fixing effect of the tail glue 60 on the battery cell 40 without reducing the energy density of the battery cell 100.

[0062] It can be understood that, in the unfolded state of the negative electrode sheet 10, the avoidance groove 122 can extend along the length direction of the negative electrode sheet 10, or can extend along an inclined direction, wherein the inclined direction is inclined with respect to the length direction of the negative electrode sheet 10. The shape of the avoidance groove 122 can be a triangle, a rectangle, a polygon or other irregular shapes, which are not limited here. In the present embodiment, preferably, the avoidance groove 122 extends along the length direction of the negative electrode sheet 10, and it can also be understood that the avoidance groove 122 extends along the winding direction of the battery cell 40, and the shape of the avoidance groove 122 is rectangular. Such a configuration can facilitate the processing of the avoidance groove 122 by the processing equipment, and can also facilitate the pasting of the finishing glue 60.

[0063] In another embodiment of the present application, please refer to Figure 3 , two avoidance grooves 122 are provided, and the two avoidance grooves 122 are respectively located at the two ends of the second negative electrode current collector 12 in the height direction of the battery cell 40. For the convenience of description, the height direction of the battery cell 40 is defined as the up and down direction. In this embodiment, the two avoidance grooves 122 are respectively located at the upper and lower ends of the second negative electrode current collector 12, so that the battery cell 40 can be fixed with two finishing glues 60, which is conducive to improving the stability of the battery cell 40 after molding and reducing the risk of the battery cell 40 spreading.

[0064] In another embodiment of the present application, please refer to Figure 3, the two avoidance grooves 122 extend to the two side surfaces of the second negative electrode current collector 12 in the height direction respectively. The avoidance groove 122 located at the upper end of the second negative electrode current collector 12 extends to the upper side surface of the second negative electrode current collector 12, and the avoidance groove 122 located at the lower end of the second negative electrode current collector 12 extends to the lower side surface of the second negative electrode current collector 12. In order to avoid the interference of the second negative electrode current collector 12 during the winding process of the finishing glue 60, there is a preset distance between the finishing glue 60 and the second negative electrode current collector 12 in the height direction of the battery cell 40, that is, in the up and down direction. The upper and lower avoidance grooves 122 extend to the upper and lower surfaces of the second negative electrode current collector 12 respectively, so that the second negative electrode current collector 12 has a larger surface area to contact with the shell 50, which is beneficial to improve the current flow capacity of the battery cell 40.

[0065] The preset distance is 10 to 30 mm. Of course, in some other embodiments, the preset distance may vary according to actual needs, so the present application does not limit the preset distance between the end-capping glue 60 and the second negative electrode current collector 12, as long as the second negative electrode current collector 12 does not interfere with the winding of the end-capping glue 60.

[0066] In another embodiment of the present application, please refer to Figure 3 The avoidance groove 122 extends to the connection between the first negative electrode current collector 11 and the second negative electrode current collector 12. In this way, the fixing part 61 of the finishing glue 60 on the battery cell 40 can be further away from the connection part in the length direction of the negative electrode sheet 10, so as to further reduce the risk of damage to the negative electrode sheet 10.

[0067] Furthermore, the avoidance groove 122 extends to an end of the second negative electrode current collector 12 away from the first negative electrode current collector 11. In this way, the length of the avoidance groove 122 can be extended, so that there is more adhesion area between the finishing glue 60 and the battery cell 40, which is conducive to improving the fixing effect of the finishing glue 60 on the battery cell 40.

[0068] In some embodiments, in the wound state of the negative electrode sheet 10 , the width of the first negative current collector 11 is greater than the width of the second negative current collector 12 . Preferably, the width of the second negative current collector 12 is 40% to 70% of the width of the first negative current collector 11 .

[0069] The present application also provides a battery, including the above-mentioned battery cell 100. The battery of the present application may be a module, a battery pack or others, which is not limited in the present application.

[0070] The present application also provides an electric device, including the above-mentioned battery cell 100 or battery. The electric device may include but is not limited to mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, etc. The electric toys may include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. The spacecraft may include airplanes, rockets, space shuttles, and spacecrafts, etc.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A battery cell, comprising a battery core (40) formed by winding a positive electrode sheet (20), a separator (30) and a negative electrode sheet (10), and a housing (50) for accommodating the battery core (40), characterized in that: The negative electrode sheet (10) comprises a first negative electrode current collector (11) and a second negative electrode current collector (12) which are sequentially connected along a winding direction, the first negative electrode current collector (11) being provided with a negative electrode active material layer (111), and the second negative electrode current collector (12) being located at the outermost layer of the battery cell (40) and being electrically connected to the shell (50).

2. The battery cell according to claim 1, characterized in that: A connecting portion is provided at one end of the second negative electrode current collector (12) away from the first negative electrode current collector (11), and the second negative electrode current collector (12) is connected to the shell (50) via the connecting portion.

3. The battery cell according to claim 2, characterized in that: The outer surface of the connecting portion is provided with a conductive adhesive (121), and the conductive adhesive (121) is bonded to the housing (50); Alternatively, the connecting portion is welded to the shell (50).

4. The battery cell according to claim 2, characterized in that: Along the winding direction of the battery cell (40), a finishing glue (60) is provided on the outer surface of the battery cell, and the second negative electrode current collector (12) is provided with at least one avoidance groove (122) for the finishing glue (60) to pass through, and the avoidance groove (122) passes through the two surfaces of the second negative electrode current collector (12) in its own thickness direction, and one end of the finishing glue (60) is bonded to the first negative electrode current collector (11), or one end of the finishing glue (60) is bonded to one end of the second negative electrode current collector (12) close to the first negative electrode current collector (11).

5. The battery cell according to claim 4, characterized in that: Two avoidance grooves (122) are provided, and the two avoidance grooves (122) are respectively located at two ends of the second negative electrode current collector (12) in the height direction of the battery core (40).

6. The battery cell according to claim 5, characterized in that: The two avoidance grooves (122) extend respectively to two side surfaces of the second negative electrode current collector (12) in the height direction.

7. The battery cell according to claim 4, characterized in that: The avoidance groove (122) extends to the connection point between the first negative electrode current collector (11) and the second negative electrode current collector (12); And / or, the avoidance groove (122) extends to a surface of the second negative electrode current collector (12) away from the first negative electrode current collector (11).

8. The battery cell according to claim 2, characterized in that: The second negative electrode current collector (12) is wound around the battery core (40) for at most five turns.

9. A battery, characterized in that: A battery cell (100) comprising any one of claims 1 to 8.

10. An electrical equipment, characterized in that: A battery cell (100) comprising any one of claims 1 to 8, or a battery according to claim 9.

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