Battery monomer, battery device and electric device

Abstract

The utility model relates to a battery monomer, a battery device and a power utilization device, the battery monomer comprises a shell and an electrode assembly, and the shell is provided with an electrode leading-out part; the electrode assembly is at least partially accommodated in the shell, the electrode assembly comprises a first pole piece, the first pole piece comprises a conductive member, a current collector and an active material layer, and the conductive member is connected with the electrode leading-out part; the current collector comprises an insulating substrate and a metal layer, the insulating substrate, the metal layer and the active material layer are stacked in the thickness direction of the current collector, and at least part of the metal layer is located between the insulating substrate and the active material layer; the metal layer comprises a conductive part and an extension part extending outwards from the end part of the conductive part along a first direction, and the first direction is perpendicular to the thickness direction of the current collector; the conductive part is covered with an active material layer, and the extension part is not covered with the active material layer; the conductive member is welded on the surface, back to the insulating substrate, of the extension part and forms a first welding mark, and the distance between the first welding mark and the active material layer ranges from 0.3 mm to 5 mm.

Description

Technical Field

[0001] This application belongs to the technical field of battery energy density, and particularly relates to a battery cell, a battery device, and an electrical device. Background Art

[0002] Battery cells are widely used in electronic devices, such as mobile phones, laptops, battery cars, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools, etc.

[0003] The battery device includes one or more battery cells to meet different capacitance usage requirements; however, in the technology of battery cells, how to improve the energy density of battery cells is an important research direction.

[0004] The above statements are only used to provide background technical information related to this application, and do not necessarily constitute prior art. Summary of the Utility Model

[0005] The purpose of the embodiments of this application is to provide a battery cell, a battery device, and an electrical device, including but not limited to being able to improve the energy density of the battery cell.

[0006] The technical solution adopted in the embodiments of this application is as follows:

[0007] In a first aspect, in some embodiments, a battery cell is provided. The battery cell includes a housing and an electrode assembly. The housing is provided with an electrode lead-out portion; at least a part of the electrode assembly is accommodated in the housing. The electrode assembly includes a first electrode tab. The first electrode tab includes a conductive member, a current collector, and an active material layer. The conductive member is connected to the electrode lead-out portion; the current collector includes an insulating matrix and a metal layer. The insulating matrix, the metal layer, and the active material layer are stacked along the thickness direction of the current collector. At least a part of the metal layer is located between the insulating matrix and the active material layer; the metal layer includes a conductive portion and an extension portion extending outward from an end of the conductive portion along a first direction. The first direction is perpendicular to the thickness direction of the current collector; the conductive portion is covered with the active material layer, and the extension portion is not covered with the active material layer; the conductive member is welded to the surface of the extension portion facing away from the insulating matrix to form a first weld mark. The distance range between the first weld mark and the active material layer is 0.3 mm to 5 mm.

[0008] By adopting the technical solution of this embodiment, when the battery cell is in normal use, the electrode lead-out part is used to input or output electric energy, realizing the charging and discharging of the battery cell; and the design with the distance range between the first welding mark and the active material layer being 0.3 mm to 5 mm makes the first welding mark not weld to the active material layer, reducing problems such as false soldering, which is beneficial to improving the connection reliability between the conductive member and the metal layer; the distance between the active material layer and the first welding mark is small, and the active material layer can be relatively close to the first welding mark. Then, when the size of the metal layer in the first direction is certain, the area that the active material layer can cover is larger, which is beneficial to improving the energy density of the battery cell; in addition, the current collector adopts a composite structure of an insulating matrix and a metal layer. Compared with a current collector made of pure metal, the thickness of the metal layer is small, and the burrs generated during the production process of the current collector are small, reducing the risk of internal short circuit of the battery cell and being beneficial to improving the use reliability of the battery cell; therefore, the battery cell of the embodiment of the present application can better balance the energy density and the use reliability.

[0009] In some embodiments, the distance range between the first welding mark and the active material layer is 0.5 mm to 2.8 mm.

[0010] By adopting the technical solution of this embodiment, the distance between the active material layer and the first welding mark is more reasonable, and the connection reliability of the conductive member and the energy density of the battery cell can be better balanced.

[0011] In some embodiments, the conductive member includes a first connection part and at least one second connection part. The first connection part and the second connection part are arranged along the first direction, the first connection part and the second connection part are connected, the second connection part is connected to the electrode lead-out part, the first connection part is welded to the surface of the extension part facing away from the insulating matrix to form a first welding mark, and the second connection part is located on the side of the extension part facing away from the conductive part.

[0012] By adopting the technical solution of this embodiment, the second connection part protrudes out of the extension part, which can facilitate the connection between the second connection part and the electrode lead-out part, and the processing and production are more convenient.

[0013] In some embodiments, along the first direction, the first welding mark is spaced from the end face of the first connection part facing the active material layer.

[0014] By adopting the technical solution of this embodiment, the first welding mark does not extend to the end face of the first connection part facing the active material layer, reducing the risks such as the end face of the first connection part facing the active material layer being welded through or cracked, being beneficial to reducing the burrs generated by welding, and being beneficial to improving the use reliability of the battery cell.

[0015] In some embodiments, along the first direction, the distance range between the first welding mark and the end face of the first connection part facing the active material layer is 0.3 mm to 1.2 mm.

[0016] By adopting the technical solution of this embodiment, the use reliability and energy density of the battery cell can be better balanced.

[0017] In some embodiments, the first welding mark includes a first welding mark portion, the extension portion includes at least one protruding portion, the protruding portion is connected to the conductive portion, and the first connecting portion is welded to the surface of the protruding portion facing away from the insulating substrate to form the first welding mark portion; along the second direction, the size of the protruding portion is smaller than the size of the conductive portion, where the second direction is perpendicular to the first direction and the thickness direction of the current collector.

[0018] By adopting the technical solution of this embodiment, the first connecting portion and the protruding portion are connected by welding, and the connection method is simple, which is convenient for the production of the first pole piece; in addition, the first connecting portion and the protruding portion can directly use the first welding mark portion for current conduction, which is beneficial to improving the current conduction ability between the first connecting portion and the protruding portion. In addition, along the second direction, the size of the protruding portion is smaller than the size of the conductive portion, and the protruding portion is easily bent with the conductive member to be connected to the electrode lead-out portion, which is convenient for processing and production, and is also beneficial to reducing the space occupied after the conductive member is bent, which is beneficial to improving the energy density of the battery cell.

[0019] In some embodiments, along the second direction, the first welding mark portion extends from one side edge of the protruding portion to the other side edge of the protruding portion.

[0020] By adopting the technical solution of this embodiment, along the second direction, the first welding mark portion can cover the entire protruding portion, and the size of the first welding mark portion along the second direction is large, which is beneficial to increasing the current conduction area between the first connecting portion and the protruding portion, beneficial to improving the current conduction ability between the first connecting portion and the protruding portion, beneficial to reducing the heating risk, and beneficial to improving the fast charging performance and use reliability of the battery cell.

[0021] In some embodiments, the protruding portion includes a first protruding sub-portion and a second protruding sub-portion, and the second protruding sub-portion is connected between the conductive portion and the first protruding sub-portion; along the second direction, the size of the second protruding sub-portion is smaller than the size of the first protruding sub-portion, and the size of the first protruding sub-portion is smaller than the size of the conductive portion; the first welding mark portion includes a first welding mark sub-portion; the first connecting portion is welded to the surface of the first protruding sub-portion facing away from the insulating substrate to form the first welding mark sub-portion.

[0022] By adopting the technical solution of this embodiment, the first connecting portion is welded to the first protruding sub-portion to form the first welding portion. The size of the first protruding sub-portion along the second direction is large, which is beneficial to increasing the welding area between the protruding portion and the first connecting portion, increasing the current conduction area between the protruding portion and the conductive portion, improving the current conduction ability, reducing the heat generation of the battery cell, and being beneficial to improving the fast charging performance and use reliability of the battery cell; in addition, along the second direction, the size of the first protruding sub-portion is small, which is beneficial to reducing the occupied space of the protruding portion and beneficial to improving the energy density of the battery cell.

[0023] In some embodiments, along the second direction, the first welding mark sub - portion extends from one side edge of the first protruding sub - portion to the other side edge of the first protruding sub - portion.

[0024] By adopting the technical solution of this embodiment, along the second direction, the size of the first welding mark sub - portion is large, which is beneficial to increasing the welding area between the protruding portion and the first connecting portion, increasing the current - carrying area between the protruding portion and the conductive portion, improving the current - carrying capacity, reducing the heat generation of the battery cell, and being beneficial to improving the fast - charging performance and use reliability of the battery cell.

[0025] In some embodiments, the first welding mark portion further includes a second welding mark sub - portion, and the first connecting portion is welded to the surface of the second protruding sub - portion facing away from the insulating substrate to form the second welding mark sub - portion.

[0026] By adopting the technical solution of this embodiment, the second protruding sub - portion is also welded to the first connecting portion, which is beneficial to increasing the current - carrying area between the first connecting portion and the protruding portion and improving the current - carrying capacity between the first connecting portion and the protruding portion.

[0027] In some embodiments, along the second direction, the second welding mark sub - portion extends from one side edge of the second protruding sub - portion to the other side edge of the second protruding sub - portion.

[0028] By adopting the technical solution of this embodiment, the size of the second welding mark sub - portion along the second direction is large, which is beneficial to increasing the welding area between the first connecting portion and the protruding portion, increasing the current - carrying area between the first connecting portion and the protruding portion, and being beneficial to improving the current - carrying capacity between the first connecting portion and the protruding portion.

[0029] In some embodiments, the number of protruding portions is multiple, the multiple protruding portions are arranged at intervals along the second direction, and each protruding portion is welded to the first connecting portion.

[0030] By adopting the technical solution of this embodiment, the multiple protruding portions are arranged at intervals along the second direction, which is beneficial to dividing the conductive portion into multiple regions along the second direction, and one region can correspond to one protruding portion. The electrons in each region can be transmitted to the electrode lead - out portion through the corresponding protruding portion, enabling the electrons in the conductive portion to be transmitted in sub - regions. The electron transmission path in each region to the corresponding protruding portion is short, which is beneficial to reducing the electron transmission distance, reducing the overall resistance of the first pole piece, and improving the fast - charging performance and use reliability of the battery cell.

[0031] In some embodiments, the first connection portion includes a plurality of first connection sub-portions which are arranged at intervals in the second direction. The number of the second connection portions is multiple, and each first connection sub-portion is connected to each second connection portion in a one-to-one correspondence; each first connection sub-portion is welded to the surface of each protruding portion facing away from the insulating substrate; each first connection sub-portion is welded to the surface of each protruding portion facing away from the insulating substrate.

[0032] By adopting the technical solution of this embodiment, the plurality of first connection sub-portions of the first connection portion are arranged at intervals in the second direction, and there is a gap between two adjacent first connection sub-portions, which can reduce the material required for the first connection portion and lower the manufacturing cost of the battery cell.

[0033] In some embodiments, the first welding mark includes a second welding mark portion. The extending portion further includes a transition portion which is connected between the protruding portion and the conductive portion. The first connection portion is welded to the surface of the transition portion facing away from the insulating substrate and forms the second welding mark portion; in the second direction, the size of the transition portion is larger than the sum of the sizes of all the protruding portions.

[0034] By adopting the technical solution of this embodiment, the surface of the transition portion facing away from the insulating substrate is welded to the first connection portion, so that a part of the current can flow directly into or out of the first connection portion through the transition portion, reducing the overcurrent pressure between the protruding portion and the transition portion, which is beneficial to reducing the heat generation at the connection between the protruding portion and the transition portion; in addition, the first connection portion and the transition portion are connected by welding, and the connection method is simple, which is beneficial to facilitating the production of the first pole piece; the first connection portion and the transition portion can directly use the second welding mark portion for overcurrent, which is beneficial to improving the overcurrent capacity between the first connection portion and the transition portion and reducing the heat generation of the battery cell.

[0035] In some embodiments, in the second direction, the size of the conductive portion is L1, and the size of the transition portion is L2, and 0.8 ≤ L2 / L1 ≤ 1.

[0036] By adopting the technical solution of this embodiment, the large size of the transition portion in the second direction is beneficial to increasing the connection area between the first connection portion and the transition portion, improving the overcurrent capacity at the connection between the first connection portion and the transition portion, improving the overcurrent capacity of the first pole piece, reducing the heat generation of the battery cell, and improving the fast charging performance of the battery cell.

[0037] In some embodiments, in the second direction, the size of the transition portion is L2, and the size of the second welding mark portion is L3, and 0.8 ≤ L3 / L2 ≤ 1.

[0038] By adopting the technical solution of this embodiment, the size in the second direction of the second welding mark portion is larger, which is beneficial to increasing the connection area between the first connection portion and the transition portion, improving the current-carrying capacity at the connection between the first connection portion and the transition portion, enhancing the current-carrying capacity of the first electrode tab, reducing the heat generation of the battery cell, and improving the fast charging performance of the battery cell.

[0039] In some embodiments, the number of the protruding portions is multiple, and the multiple protruding portions are arranged at intervals in the second direction, where the second direction is perpendicular to the first direction and the thickness direction of the current collector; the first connection portion includes a second connection sub-portion and multiple first connection sub-portions, the multiple first connection sub-portions are arranged at intervals in the second direction, and each first connection sub-portion is welded to the surface of each protruding portion facing away from the insulating substrate one by one; the number of the second connection portions is multiple, and along the first direction, one side of each first connection sub-portion is connected to each second connection portion one by one, and the other side of each first connection sub-portion is connected to the second connection sub-portion, and the second connection sub-portion is continuously arranged in the second direction; the second connection sub-portion is welded to the surface of the transition portion facing away from the insulating substrate.

[0040] By adopting the technical solution of this embodiment, the second connection sub-portion is continuously arranged in the second direction, which can connect the multiple first connection sub-portions into a whole. The second connection sub-portion can play a good supporting role for the first connection sub-portions, can reduce the risk of the first connection sub-portions being bent when inserted between the first electrode tab and the second electrode tab, reduce the risk of short circuit, and is beneficial to improving the service reliability of the battery cell; in addition, along the second direction, the size of the second connection sub-portion is large, which is beneficial to increasing the welding area between the second connection sub-portion and the transition portion, beneficial to improving the current-carrying capacity at the connection between the first connection portion and the transition portion, enhancing the current-carrying capacity of the first electrode tab, and improving the fast charging performance and service reliability of the battery cell.

[0041] In some embodiments, along the first direction, the first connection portion and the active material layer are arranged at intervals.

[0042] By adopting the technical solution of this embodiment, the first connection portion does not contact the active species layer, which can reduce the mutual influence between the two and improve the service reliability of the battery cell.

[0043] In some embodiments, the electrode assembly further includes an insulating member, and the insulating member includes a first insulating portion, and the first insulating portion covers the surface of the extending portion facing away from the insulating substrate, and the entire first insulating portion is located between the first welding mark and the active material layer.

[0044] By adopting the technical solution of this embodiment, it is beneficial to reducing the risk of virtual soldering between the first connection portion and the extending portion, beneficial to reducing the risk of virtual soldering between the first connection portion and the extending portion, improving the connection reliability between the first connection portion and the extending portion, and also beneficial to improving the current-carrying capacity.

[0045] In some embodiments, the first insulating portion is located between the first connecting portion and the active material layer.

[0046] By adopting the technical solution of this embodiment, the first insulating portion can support the part of the extending portion located between the first connecting portion and the active material layer, reduce damages such as cracks and fractures that occur in this part during the manufacturing process of the battery device, be conducive to improving the electron transport ability of this part, and improving the fast charging performance and service reliability of the battery cell; in addition, the first insulating portion can also insulate this part, reduce the short - circuit risk of the battery cell, and improve the service reliability of the battery cell.

[0047] In some embodiments, the insulating member further includes a second insulating portion, and at least a part of the second insulating portion covers the first welding mark.

[0048] By adopting the technical solution of this embodiment, the second insulating portion can prevent components such as tip protrusions and metal debris on the surface of the first welding mark from piercing the separator and connecting with the second pole piece, reduce the short - circuit risk of the battery cell, and improve the service reliability of the battery cell.

[0049] In some embodiments, along the first direction, one side of the second insulating portion covers the first welding mark, and the other side of the second insulating portion covers at least a part of the first insulating portion.

[0050] By adopting the technical solution of this embodiment, the second insulating portion and the first insulating portion jointly cover the extending portion, which can achieve double - layer insulation, be conducive to reducing the short - circuit risk of the battery cell, and be conducive to improving the service reliability of the battery cell.

[0051] In some embodiments, the electrode assembly further includes an insulating member, the insulating member includes a second insulating portion, and at least a part of the second insulating portion covers the first welding mark.

[0052] By adopting the technical solution of this embodiment, the second insulating portion covers the surface of the first welding mark, can prevent components such as tip protrusions and metal debris on the surface of the first welding mark from piercing the separator and connecting with the second pole piece, reduce the short - circuit risk of the battery cell, and improve the service reliability of the battery cell.

[0053] In some embodiments, along the first direction, one side of the second insulating portion covers the first welding mark, and the other side of the second insulating portion covers at least a part of the active material layer.

[0054] By adopting the technical solution of this embodiment, the second insulating portion extends from the first welding mark to the active material layer, the covering area of the second insulating portion is wide, and the insulation effect is good, which is conducive to improving the service reliability of the battery cell.

[0055] In some embodiments, the number of metal layers is two, and the two metal layers are disposed on opposite sides of the insulating substrate along the thickness direction of the current collector. The number of active material layers is two, and the two active material layers respectively cover the two metal layers. The number of conductive members is two, and the first connection portions of the two conductive members are respectively welded to the surfaces of the two metal layers facing away from the insulating substrate to form two first solder marks. The number of insulating members is two, and the second insulating portions of the two insulating members respectively cover at least a part of the two first solder marks.

[0056] By adopting the technical solution of this embodiment, the first connection portions of the two conductive members are respectively welded to the metal layers located on opposite sides of the insulating substrate, and the second connection portions of the two conductive members are located on the side of the extension portion facing away from the conductive portion. In this way, the two metal layers can be directly connected by the second connection portions of the two conductive members, thereby breaking the insulation limitation of the insulating substrate, effectively improving the conductivity of the first electrode plate, improving the fast charging performance of the battery cell, reducing heat generation, and improving the use reliability of the battery cell metal layer.

[0057] In some embodiments, the second insulating portion includes a first portion and a second portion connected to each other. The first portion covers at least a part of the first solder mark. Along the direction of the conductive portion towards the extension portion, the second portion protrudes from the extension portion, and the second portion is located on the side of the second connection portion along the second direction, where the second direction is perpendicular to the first direction and the thickness direction of the current collector.

[0058] By adopting the technical solution of this embodiment, along the direction of the conductive portion pointing to the extension portion, components such as metal debris at the end face of the extension portion away from the active material layer can be located between the second portions of the two insulating members. In this way, the risk of metal debris falling into the electrode assembly can be reduced, which is beneficial to reducing the risk of short circuit.

[0059] In some embodiments, the second portions of the two insulating members are in contact with each other.

[0060] By adopting the technical solution of this embodiment, after the second portions of the two insulating members are in contact with each other, components such as metal debris at the end face of the extension portion away from the active material layer can be wrapped, so that the components such as metal debris are not easily fallen into the electrode assembly, and the short circuit risk of the battery cell can be better reduced.

[0061] In some embodiments, the second connection portions of the two conductive members are welded to form a second solder mark.

[0062] By adopting the technical solution of this embodiment, the second connection portions of the two conductive members are directly welded. On the one hand, the metal layers located on opposite sides of the insulating substrate can be connected, thereby breaking the insulation limitation of the insulating substrate, effectively improving the conductivity of the first electrode plate, improving the fast charging performance of the battery cell, reducing the heat generation of the battery cell, and improving the use reliability of the battery cell. On the other hand, the welding operation is simple and convenient for processing and manufacturing.

[0063] In some embodiments, the second insulating portion covers the second solder pad, and along the direction from the conductive portion to the extending portion, the second insulating portion protrudes from the edge of the second solder pad facing away from the conductive portion.

[0064] By adopting the technical solution of this embodiment, the second insulating portion can completely cover the second solder pad, and can prevent components such as tip protrusions and metal debris on the second solder pad from piercing the separator and connecting to the second pole piece, reducing the risk of short circuit and improving the reliability of use of the battery cell.

[0065] In some embodiments, the electrode assembly includes a second pole piece having a polarity opposite to that of the first pole piece. The second pole piece includes a main functional portion and a pole ear portion, and the pole ear portion protrudes from the main functional portion along a first direction; along the direction from the conductive portion to the extending portion, the main functional portion protrudes from the end face of the insulating member facing the active material layer, and the main functional portion does not protrude from the end face of the insulating member away from the active material layer.

[0066] By adopting the technical solution of this embodiment, the insulating member can prevent burrs at the end face of the main functional portion of the second pole piece near the pole ear portion from piercing the separator and connecting to the first pole piece, reducing the risk of short circuit between the first pole piece and the second pole piece, and being beneficial to improving the reliability of use of the battery cell.

[0067] In some embodiments, the electrode assembly includes a second pole piece having a polarity opposite to that of the first pole piece. The second pole piece includes a main functional portion and a pole ear portion, and the pole ear portion protrudes from the main functional portion along a first direction; along the direction from the conductive portion to the extending portion, the main functional portion protrudes from the end face of the extending portion facing away from the conductive portion.

[0068] By adopting the technical solution of this embodiment, the burrs at the end face of the main functional portion of the second pole piece facing the pole ear portion correspond to the hollowed-out area where the metal layer does not extend beyond the second connecting portion, which can also reduce the risk of short circuit of the battery cell and improve the reliability of use of the battery cell.

[0069] In some embodiments, the current collector further includes a conductive protection layer, and at least a part of the conductive protection layer is located between the active material layer and the conductive portion.

[0070] By adopting the technical solution of this embodiment, the conductive protection layer can separate the active material layer and the metal layer and play a protective role for the metal layer, reducing risks such as cracks generated in the metal layer due to rolling of the active material layer, and being beneficial to improving the current-carrying capacity of the metal layer.

[0071] In some embodiments, along the direction from the conductive portion to the extending portion, the conductive protection layer protrudes from the end face of the active material layer near the extending portion.

[0072] By adopting the technical solution of this embodiment, the conductive protective layer can completely separate the active material layer and the metal layer, the conductive protective layer has better protection ability for the metal layer, the current-carrying capacity of the first electrode sheet is better, which is beneficial to improving the fast charging performance and use reliability of the battery cell.

[0073] In some embodiments, along the direction of the conductive part towards the extending part, the protruding distance range of the conductive protective layer from the end face of the active material layer towards the extending part is 0.3 mm to 0.8 mm.

[0074] By adopting the technical solution of this embodiment, the current-carrying capacity and energy density of the battery cell can be better balanced.

[0075] In some embodiments, along the first direction, the conductive protective layer and the first welding mark are arranged at intervals.

[0076] By adopting the technical solution of this embodiment, the first connecting part will not be welded to the conductive protective layer, which can reduce risks such as false soldering and is beneficial to improving the welding reliability between the first connecting part and the metal layer.

[0077] In some embodiments, at least part of the thickness of the conductive part is less than the thickness of the extending part.

[0078] By adopting the technical solution of this embodiment, the extending part has a larger thickness and better current-carrying capacity, which is beneficial to improving the current-carrying capacity of the first electrode sheet, reducing the heat generation of the battery cell, and is beneficial to improving the fast charging performance and use reliability of the battery cell.

[0079] In some embodiments, the current collector further includes a conductive protective layer, the conductive protective layer includes a first protective part and a second protective part, the first protective part is located between the first sub-part and the active material layer, and the second protective part is located between the second sub-part and the active material layer, wherein the thickness of the first protective part is less than the thickness of the second protective part.

[0080] By adopting the technical solution of this embodiment, the current-carrying capacity of the first sub-part close to the transition part is greater than that of the second sub-part far from the transition part, which can reduce the restriction on the current, improve the current-carrying capacity of the first electrode sheet, reduce the heat generation of the battery cell, and is beneficial to improving the use reliability of the battery cell.

[0081] In some embodiments, the current collector further includes a conductive protective layer, the conductive protective layer includes a first protective part and a second protective part, the first protective part is located between the first sub-part and the active material layer, and the second protective part is located between the second sub-part and the active material layer, where the thickness of the first protective part is less than the thickness of the second protective part.

[0082] By adopting the technical solution of this embodiment, the surface of the conductive protective layer facing away from the insulating substrate is close to a plane, which is beneficial to reducing rolling damage and improving the current-carrying capacity of the metal layer. In addition, the problem of winding bulging of the current collector can also be reduced.

[0083] In some embodiments, the conductive protective layer further includes a third protective part, the third protective part covers the surface of the extending part facing away from the insulating substrate, and the thickness of the third protective part is less than or equal to the thickness of the first protective part.

[0084] By adopting the technical aspect of this embodiment, the setting of the third protective part can make the conductive protective layer protrude from the active material layer, so that the active material layer and the metal layer can be better separated. In addition, the thickness of the third protective part is not too large, which is beneficial to reducing material waste and saving the manufacturing cost of the battery cell.

[0085] In a second aspect, a battery device is provided, including the battery cell of the above embodiment.

[0086] The battery device of the embodiment of the present application adopts the above battery cell. The battery cell has a large energy density, and the battery device also has a large energy density.

[0087] In a third aspect, an electrical device is provided, including the battery device of the above embodiment.

[0088] The electrical device of the embodiment of the present application adopts the above battery device. The battery cell has a large energy density, which is beneficial to improving the endurance and performance of the electrical device.

[0089] The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present application more obvious and understandable, the specific embodiments of the present application are given below. BRIEF DESCRIPTION OF THE DRAWINGS

[0090] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0091] Figure 1 It is a schematic structural diagram of a vehicle provided for some embodiments of the present application.

[0092] Figure 2 It is an exploded view of a battery device provided for some embodiments of the present application.

[0093] Figure 3Exploded view of a battery cell provided by some embodiments of the present application.

[0094] Figure 4 Structural schematic diagram of an electrode assembly provided by some embodiments of the present application.

[0095] Figure 5 Along Figure 4 Sectional view taken along line A-A in

[0096] Figure 6 Structural schematic diagram of a first electrode tab provided by some embodiments of the present application.

[0097] Figure 7 Along Figure 6 Sectional view taken along line B-B in

[0098] Figure 8 For Figure 6 Partial enlarged view at C in

[0099] Figure 9 Structural schematic diagram of the first electrode tab with the conductive member hidden, provided by some embodiments of the present application.

[0100] Figure 10 For Figure 9 Partial enlarged view at D in

[0101] Figure 11 Structural schematic diagram of a first electrode tab provided by other embodiments of the present application.

[0102] Figure 12 For Figure 11 Partial enlarged view at E in

[0103] Figure 13 For Figure 11 Structural schematic diagram of the first electrode tab shown with the conductive member hidden.

[0104] Figure 14 For Figure 13 Partial enlarged view at F in

[0105] Figure 15 Structural schematic diagram of a first electrode tab provided by yet other embodiments of the present application.

[0106] Figure 16 Along Figure 15 Sectional view taken along line H-H in

[0107] Figure 17 Along Figure 15 Sectional view taken along line I-I in

[0108] Figure 18 Structural schematic diagram of a first electrode tab provided by yet other embodiments of the present application.

[0109] Figure 19 is Figure 18 a partial enlarged view at position J in

[0110] Figure 20 is a schematic structural view of a first pole piece provided by some other embodiments of the present application.

[0111] Figure 21 is along Figure 20 a sectional view taken along line K-K in

[0112] Figure 22 is a schematic structural view of a second insulating part provided by some embodiments of the present application.

[0113] Figure 23 is along Figure 22 a sectional view taken along line N-N in

[0114] Among them, each reference numeral in the figure:

[0115] 1000, vehicle; 1100, battery device; 1200, controller; 1300, motor; 100, battery cell; 101, electrode assembly; 1, first pole piece; 10, current collector; 11, insulating substrate; 12, metal layer; 121, conductive part; 1211, first sub-part; 1212, second sub-part; 122, extension part; 1221, transition part; 1222, protruding part; 12221, first protruding sub-part; 12222, second protruding sub-part; 13, conductive protective layer; 131, first protection part; 132, second protection part; 133, third protection part; 20, active material layer; 21, first active material part; 22, second active material part; 30, conductive member; 31, first connection part; 311, first connection sub-part; 312, second connection sub-part; 32, second connection part; 40, insulating part; 41, first insulating part; 42, second insulating part; 421, first part; 422, second part; 423, insulating base layer; 424, adhesive layer; 51, first welding mark; 511, first welding mark part; 5111, first welding mark sub-part; 5112, second welding mark sub-part; 512, second welding mark part; 52, second welding mark; 2, second pole piece; 210, main functional part; 220, pole ear part; 3, separator; 200, housing; 201, end cover; 2011, electrode lead-out part; 202, housing body; 300, box body; 301, first box body part; 302, second box body part. Detailed implementation manners

[0116] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer and more understandable, the following combines the attached Figures 1 - 23Examples are provided below to further elaborate on this application. It should be understood that the specific examples described herein are merely for the purpose of explaining this application and are not intended to limit this application.

[0117] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion.

[0118] In the description of the embodiments of this application, the technical terms "first", "second", etc. are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order or primary-secondary relationship of the indicated technical features. Thus, features defined with "first", "second" may explicitly or implicitly include one or more of such features.

[0119] In the description of the embodiments of this application, the term "and / or" is merely a description of the relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Additionally, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0120] In the description of the embodiments of this application, the term "plurality" refers to two or more (including two). Similarly, "multiple groups" refers to two or more groups (including two groups), and "multiple pieces" refers to two or more pieces (including two pieces). The meaning of "several" is one or more, unless otherwise specifically defined.

[0121] In the description of the embodiments of this application, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of this application and simplifying the description, and does 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 thus cannot be understood as a limitation to the embodiments of this application.

[0122] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "coupling", "fixation" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral body; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0123] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0124] In the embodiments of the present application, the battery cell can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging so as to continue to be used.

[0125] The battery cell can include but is not limited to lithium-ion battery cells, sodium-ion battery cells, sodium-lithium-ion battery cells, lithium metal battery cells, sodium metal battery cells, lithium-sulfur battery cells, magnesium-ion battery cells, nickel-metal hydride battery cells, nickel-cadmium battery cells, lead-acid battery cells, etc.

[0126] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell or a battery cell of other shapes. The prismatic battery cell includes a square-shell battery cell, a blade-shaped battery cell, a multi-prismatic battery cell, and the multi-prismatic battery cell is, for example, a hexagonal-prismatic battery cell, etc.

[0127] The battery device mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.

[0128] In some embodiments, the battery device can be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0129] In some embodiments, the battery device can be a battery pack, and the battery pack includes a box body and battery cells, and the battery cells or the battery module are accommodated in the box body.

[0130] In some embodiments, the box body can be a part of the chassis structure of a vehicle. For example, a part of the box body can become at least a part of the floor of the vehicle, or a part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0131] In some embodiments, the battery device can be an energy storage device. The energy storage device includes an energy storage container, an energy storage electrical cabinet, etc.

[0132] A battery cell generally includes an electrode assembly and a casing, and the electrode assembly is accommodated in the casing. The electrode assembly includes a positive electrode and a negative electrode. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are embedded and extracted back and forth between the positive electrode and the negative electrode.

[0133] In some embodiments, the electrode assembly further includes a separator, which is disposed between the positive electrode and the negative electrode, and can play a role in preventing short circuit between the positive and negative electrodes, and at the same time allows active ions to pass through.

[0134] The casing is used to encapsulate components such as the electrode assembly and the electrolyte. The casing can be a steel casing, an aluminum casing, a plastic casing (such as polypropylene), a composite metal casing (such as a copper-aluminum composite casing), or an aluminum plastic film, etc.

[0135] In some embodiments, the positive electrode can be a positive electrode plate, and the positive electrode plate can include a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector. The negative electrode can be a negative electrode plate, and the negative electrode plate can include a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector.

[0136] The current collector (positive electrode current collector or negative electrode current collector) is usually made of a metal material, such as metal aluminum foil and metal copper foil. However, pure metal foils are prone to generate metal burrs, and the burrs penetrate the separator, resulting in an internal short circuit, posing a greater risk of fire and explosion for the battery cell.

[0137] In order to reduce the short circuit risk inside the battery cell, a current collector is proposed. The current collector includes an insulating matrix and a metal layer covering the surface of the insulating matrix, and the active material layer covers the surface of the metal layer facing away from the insulating matrix. The thickness of the metal layer is usually set to be small, so that during the process of a foreign object piercing the electrode plate, the burrs generated by the metal layer are small and not easily penetrate the separator. However, the capacity of the active material covering the surface of the metal layer is small, which is not conducive to improving the energy density of the battery cell.

[0138] Based on this, the embodiments of the present application provide a technical solution. The conductive member of the battery cell is welded to the extension of the conductive portion to form a first welding mark, and the distance range between the first welding mark and the active material layer is 0.3 mm to 5 mm. This small distance range makes the active material layer closer to the first welding mark, which is equivalent to increasing the coverage area of the active material layer on the metal layer and is beneficial to improving the energy density of the battery cell.

[0139] The battery cell described in the embodiments of the present application is applicable to the battery device and the electrical device using the battery device.

[0140] The battery device disclosed in the embodiments of the present application can be used in electrical devices that use the battery device as a power source or various energy storage systems that use the battery device as an energy storage element. The electrical device can be, but is not limited to, a mobile phone, a tablet computer, a laptop computer, an electric toy, a power tool, a battery car, an electric vehicle, a ship, a spacecraft, etc. Among them, the electric toy can include a fixed or mobile electric toy, for example, a game console, an electric vehicle toy, an electric ship toy, an electric aircraft toy, etc., and the spacecraft can include an airplane, a rocket, a space shuttle, a spaceship, etc.

[0141] For the convenience of description, the following embodiments will be described by taking the electrical device as a vehicle as an example.

[0142] As Figure 1 shown, a battery device 1100 is disposed inside the vehicle 1000, and the battery device 1100 can be disposed at the bottom, head or tail of the vehicle 1000. The battery device 1100 can be used for power supply of the vehicle 1000. For example, the battery device 1100 can be used as an operating power source of the vehicle 1000.

[0143] The vehicle 1000 may further include a controller 1200 and a motor 1300. The controller 1200 is used to control the battery device 1100 to supply power to the motor 1300. For example, it is used for the working power requirements during the start, navigation and driving of the vehicle 1000.

[0144] In some embodiments of the present application, the battery device 1100 can not only be used as an operating power source of the vehicle 1000, but also be used as a driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000. Figure 2 An exploded view of the battery device 1100 provided in some embodiments of the present application. As Figure 2 shown, the battery device 1100 includes a box body 300 and battery cells 100, and the battery cells 100 are accommodated in the box body 300.

[0145] The housing 300 is used to accommodate the battery cells 100, and the housing 300 can have various structures. In some embodiments, the housing 300 can include a first housing part 301 and a second housing part 302. The first housing part 301 and the second housing part 302 cover each other, and the first housing part 301 and the second housing part 302 together define an accommodation space for accommodating the battery cells 100. The second housing part 302 can be a hollow structure with one end open, and the first housing part 301 is a plate-like structure. The first housing part 301 covers the open side of the second housing part 302 to form the housing 300 with an accommodation space; both the first housing part 301 and the second housing part 302 can also be hollow structures with one side open, and the open side of the first housing part 301 covers the open side of the second housing part 302 to form the housing 300 with an accommodation space. Of course, the first housing part 301 and the second housing part 302 can have various shapes, such as a cylinder, a cuboid, etc.

[0146] To improve the sealing performance after the connection between the first housing part 301 and the second housing part 302, a sealing member can also be provided between the first housing part 301 and the second housing part 302, such as sealant, sealing ring, etc.

[0147] Assuming that the first housing part 301 covers the top of the second housing part 302, the first housing part 301 can also be referred to as the upper cover, and the second housing part 302 can also be referred to as the lower housing.

[0148] In the battery device 1100, there can be one or multiple battery cells 100. If there are multiple battery cells 100, the multiple battery cells 100 can be connected in series, in parallel, or in a hybrid connection. A hybrid connection means that there are both series and parallel connections among the multiple battery cells 100.

[0149] The multiple battery cells 100 can be directly connected in series, in parallel, or in a hybrid connection together, and then the whole formed by the multiple battery cells 100 is accommodated in the housing 300; of course, it can also be that the multiple battery cells 100 are first connected in series, in parallel, or in a hybrid connection to form battery modules, and then the multiple battery modules are connected in series, in parallel, or in a hybrid connection to form a whole and are accommodated in the housing 300.

[0150] Exemplarily, the battery cell 100 can be the smallest unit constituting the battery device 1100.

[0151] Such as Figure 3As shown, in some embodiments, the battery cell 100 includes a housing 200 and an electrode assembly 101 accommodated in the housing 200. The electrode assembly 101 includes a positive electrode and a negative electrode. During the charging and discharging process of the battery cell 100, active ions (such as lithium ions) are embedded and extracted back and forth between the positive electrode and the negative electrode. Optionally, the electrode assembly 101 further includes a separator 3 disposed between the positive electrode and the negative electrode. The separator 3 can reduce the risk of short circuit between the positive and negative electrodes and at the same time allow the active ions to pass through.

[0152] The housing 200 is used to encapsulate components such as the electrode assembly 101 and the electrolyte.

[0153] In some embodiments, the housing 200 includes a housing body 202 and an end cap 201. The housing body 202 has an opening, and the end cap 201 is used to cover the opening.

[0154] The housing body 202 is a component used to cooperate with the end cap 201 to form an internal cavity of the battery cell 100. The formed internal cavity can be used to accommodate the electrode assembly 101, the electrolyte, and other components.

[0155] The housing body 202 and the end cap 201 can be independent components. Exemplarily, an opening can be provided on the housing body 202, and the end cap 201 is covered at the opening to form an internal cavity of the battery cell 100.

[0156] The housing body 202 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing body 202 can be determined according to the specific shape and size of the electrode assembly 101. The material of the housing body 202 can be various. For example, the material of the housing body 202 includes but is not limited to copper, iron, aluminum, stainless steel, aluminum alloy, aluminum plastic film, steel plastic film, etc.

[0157] The shape of the end cap 201 can be adapted to the shape of the housing body 202 to cooperate with the housing body 202. The material of the end cap 201 can be the same as or different from the material of the housing body 202. Optionally, the end cap 201 can be made of a material with certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.). In this way, the end cap 201 is not easily deformed when being squeezed or collided, enabling the battery cell 100 to have higher structural strength and improved reliability.

[0158] The end cap 201 is connected to the housing body 202 by welding, bonding, clamping or other means.

[0159] The housing 202 may have an opening at one end or openings at both ends. In some examples, the housing 202 may be a structure with an opening on one side, and the end cap 201 is provided as one and covers the housing 202. In other examples, the housing 202 may also be a structure with openings on both sides, and the end caps 201 are provided as two, and the two end caps 201 respectively cover the two openings of the housing 202.

[0160] In some embodiments, the battery cell 100 includes electrode lead-out portions 2011. The number of the electrode lead-out portions 2011 is two, and the two electrode lead-out portions 2011 are respectively connected to the positive electrode plate and the negative electrode plate to output or input the electric energy of the battery cell 100.

[0161] In some embodiments, the battery cell 100 further includes an electrolyte accommodated in the outer shell 200. The electrolyte functions to conduct ions between the positive and negative electrodes. The electrolyte can be liquid, gel or solid.

[0162] In some embodiments, the liquid electrolyte includes an electrolyte salt and a solvent.

[0163] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluoro bis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0164] In some embodiments, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0165] The solvent may also be an ether solvent. The ether solvent may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether, and crown ether.

[0166] In some embodiments, the gel electrolyte includes a polymer as the skeleton network of the electrolyte, combined with an ionic liquid-lithium salt.

[0167] In some embodiments, the solid electrolyte includes a polymer solid electrolyte, an inorganic solid electrolyte, and a composite solid electrolyte.

[0168] As an example, the polymer solid electrolyte can be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, single-ion polymer, polyionic liquid-lithium salt, cellulose, etc.

[0169] As an example, the inorganic solid electrolyte can be an oxide solid electrolyte (crystalline perovskite, sodium superionic conductor, garnet, amorphous LiPON film), a sulfide solid electrolyte (crystalline lithium superionic conductor (lithium germanium phosphorus sulfur, argyrodite), amorphous sulfide), and one or more of a halide solid electrolyte, a nitride solid electrolyte, and a hydride solid electrolyte.

[0170] As an example, the composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0171] Referring to Figure 4 and Figure 5 , the electrode assembly 101 of the embodiment of the present application includes a first pole piece 1 and a second pole piece 2 with opposite polarities.

[0172] Exemplarily, one of the first pole piece 1 and the second pole piece 2 is a positive electrode piece, and the other is a negative electrode piece.

[0173] In some embodiments, the positive electrode piece may include a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector.

[0174] As an example, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode active material layer is provided on any one or both of the two opposite surfaces of the positive electrode current collector.

[0175] As an example, the positive electrode current collector can be made of carbon, metal foil, or composite current collector. For example, as the metal foil, stainless steel, copper, aluminum, nickel, carbon electrode, nickel, titanium, aluminum or stainless steel with silver surface treatment, etc. can be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0176] As an example, the positive electrode active material layer includes a positive electrode active material, which may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. Other conventional materials that can be used as the positive electrode active material layer of the battery device 1100 may also be used for the positive electrode active material. These positive electrode active materials can be used alone or in combination of two or more. Examples of lithium-containing phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO4 (which can also be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and at least one of a composite material of lithium manganese iron phosphate and carbon. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which can also be abbreviated as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be abbreviated as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which can also be abbreviated as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which can also be abbreviated as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which can also be abbreviated as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi 0.80 Co 0.15 Al 0.05 O2) and at least one of their modified compounds, etc.

[0177] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector.

[0178] As an example, the negative electrode current collector can be a metal foil, a foam metal, or a composite current collector. For example, as the metal foil, aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrodes, nickel, or titanium, etc. can be used. The foam metal can be foam nickel, foam copper, foam aluminum, foam alloy, or foam carbon, etc. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as substrates of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0179] As an example, the negative electrode active material layer includes a negative electrode active material. The negative electrode active material can be the negative electrode active material known in the art for the battery cell 100. As an example, the negative electrode active material can include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based materials can include at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based materials can include at least one of elemental tin, tin oxides, and tin alloys. The negative electrode active material of the present application can also use other conventional materials that can be used as the negative electrode active material of the battery device 1100. These negative electrode active materials can be used alone or in combination of two or more.

[0180] In some embodiments, the material of the positive electrode current collector can be aluminum, and the material of the negative electrode current collector can be copper.

[0181] In some embodiments, the electrode assembly 101 further includes a separator 3, and the separator 3 is used to separate the first electrode sheet 1 and the second electrode sheet 2. The separator 3 can reduce the risk of short circuit between the positive and negative electrodes, and at the same time allow active ions to pass through.

[0182] In some embodiments, the separator 3 includes a separator membrane. The separator membrane of the present application can be any known porous structure separator membrane with good chemical stability and mechanical stability.

[0183] As an example, the main materials of the separator membrane can include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramics. The separator membrane can be a single-layer film or a multi-layer composite film. When the separator membrane is a multi-layer composite film, the materials of each layer can be the same or different. The separator 3 can be a separate component located between the positive and negative electrodes, or can be attached to the surfaces of the positive and negative electrodes.

[0184] In some embodiments, the separator 3 is a solid electrolyte. The solid electrolyte is disposed between the positive electrode sheet and the negative electrode sheet, and simultaneously functions to transport ions and isolate the positive and negative electrodes.

[0185] In some embodiments, the electrode assembly 101 has a wound structure. Exemplarily, both the first electrode tab 1 and the second electrode tab 2 are strip-shaped structures, and the first electrode tab 1, the separator 3, and the second electrode tab 2 are wound into a wound structure.

[0186] In some embodiments, the electrode assembly 101 has a stacked structure.

[0187] As an example, multiple first electrode tabs 1 and multiple second electrode tabs 2 may be respectively provided, and the multiple first electrode tabs 1 and the multiple second electrode tabs 2 are alternately stacked.

[0188] As an example, multiple first electrode tabs 1 may be provided, and the second electrode tab 2 is folded to form multiple folded segments arranged in a stacked manner, and one first electrode tab 1 is clamped between adjacent folded segments.

[0189] As an example, both the first electrode tab 1 and the second electrode tab 2 are folded to form multiple folded segments arranged in a stacked manner.

[0190] As an example, multiple separators 3 may be provided and are respectively disposed between any adjacent first electrode tab 1 or second electrode tab 2.

[0191] As an example, the separator 3 may be continuously provided and is disposed between any adjacent first electrode tab 1 or second electrode tab 2 by means of folding or winding.

[0192] In some embodiments, the shape of the electrode assembly 101 may be cylindrical, flat, or prismatic, etc.

[0193] Please refer to Figures 6 - 10 As shown, in some embodiments, a battery cell 100 is provided. The battery cell 100 includes a housing 200 and an electrode assembly 101. The housing 200 is provided with an electrode lead-out portion 2011; at least a part of the electrode assembly 101 is accommodated in the housing 200. The electrode assembly 101 includes a first electrode tab 1. The first electrode tab 1 includes a conductive member 30, a current collector 10, and an active material layer 20. The conductive member 30 is connected to the electrode lead-out portion 2011; the current collector 10 includes an insulating substrate 11 and a metal layer 12. The insulating substrate 11, the metal layer 12, and the active material layer 20 are stacked along the thickness direction of the current collector 10, and at least a part of the metal layer 12 is located between the insulating substrate 11 and the active material layer 20; the metal layer 12 includes a conductive portion 121 and an extension portion 122 extending outward from an end of the conductive portion 121 in a first direction. The first direction is perpendicular to the thickness direction of the current collector 10; the conductive portion 121 is covered with the active material layer 20, and the extension portion 122 is not covered with the active material layer 20; the conductive member 30 is welded to the surface of the extension portion 122 facing away from the insulating substrate 11 to form a first weld mark 51, and the distance between the first weld mark 51 and the active material layer 20 ranges from 0.3 mm to 5 mm.

[0194] A part of the electrode assembly 101 is located inside the housing 200; another part is located outside the housing 200, or the entire electrode assembly 101 is located inside the housing 200.

[0195] In some examples, the first electrode tab 1 is a positive electrode tab, the current collector 10 is a positive current collector, the positive current collector adopts a composite current collector structure, and the active material layer 20 is a positive active material layer; or, the first electrode tab 1 is a negative electrode tab, the current collector 10 is a negative current collector, the negative current collector is a composite current collector structure, and the active material layer 20 is a negative active material layer.

[0196] The conductive member 30 may refer to a component for connecting the electrode lead-out portion 2011 and the current collector 10. The conductive member 30 may adopt copper foil or aluminum foil to facilitate connection with the electrode lead-out portion 2011.

[0197] The electrode lead-out portion 2011 may refer to a conductive component for outputting or inputting electric energy. The electrode lead-out portion 2011 is connected to an external electronic device so that the battery cell 100 outputs or inputs electric energy; the electrode lead-out portion 2011 is also called a pole column. The electrode lead-out portion 2011 may be provided on the housing 202 or on the end cap 201.

[0198] The electrode lead-out portion 2011 is connected to the conductive member 30. The electrode lead-out portion 2011 may be directly connected to the conductive member 30; for example: the electrode lead-out portion 2011 is directly welded to the conductive member 30; or, the electrode lead-out portion 2011 may be connected to the conductive member 30 through a conductive part (such as a transition piece, etc.). For example: one end of the conductive part is welded to the conductive member 30, and the other end of the conductive part is welded to the electrode lead-out portion 2011.

[0199] The current collector 10 includes a metal layer 12 and an insulating matrix 11. The current collector 10 is a multi-layer structure. The insulating matrix 11 may refer to a component made of an insulating material (such as the above-mentioned polymer base material) in the current collector 10, and the metal layer 12 may refer to a component made of the above-mentioned metal material in the current collector 10.

[0200] The surface of the insulating matrix 11 is covered with a metal layer 12, and the surface of the metal layer 12 facing away from the insulating matrix 11 is covered with an active material layer 20, so that the insulating matrix 11, the metal layer 12, and the active material layer 20 are stacked, and the stacking direction of the insulating matrix 11, the metal layer 12, and the active material layer 20 is the thickness direction of the current collector 10 (see the Y direction in Figure 7 ). Among them, the active material layer 20 may be directly covered on the surface of the metal layer 12, or other substances may be covered on the surface of the metal layer 12 and then the active material layer 20 may be covered.

[0201] In some examples, one surface of the insulating matrix 11 is covered with a metal layer 12.

[0202] In some examples, both opposite surfaces of the insulating substrate 11 are covered with metal layers 12. Among the two metal layers 12, at least one surface of the metal layer 12 facing away from the insulating substrate is covered with an active material layer 20.

[0203] The first direction may refer to a direction perpendicular to the thickness direction of the current collector 10; the second direction may refer to a direction perpendicular to the thickness direction of the current collector 10 and the first direction.

[0204] In some examples, the electrode assembly 101 has a wound structure. When the first electrode sheet 1 is in the unfolded state, the first direction can refer to the width direction of the first electrode sheet 1 (which can refer to the Z direction in Figure 6 ); the second direction can refer to the length direction of the first electrode sheet 1 (which can refer to the X direction in Figure 6 ). When the first electrode sheet 1 is in the wound state, the second direction can also refer to the winding direction of the first electrode sheet 1 (which can refer to the direction indicated by the arrow V in Figure 4 ).

[0205] In some examples, the electrode assembly 101 has a stacked structure. The first direction can be the width direction of the first electrode sheet 1 (which can refer to the Z direction in Figure 6 ), and the second direction can refer to the length direction of the first electrode sheet 1 (which can refer to the X direction in Figure 6 ).

[0206] Along the first direction, the metal layer 12 is divided into two parts. The part covered with the active material layer 20 is the conductive part 121, and the part not covered with the active material layer 20 is the extension part 122. The conductive part 121 has an equal-width structure, and the extension part 122 can also have a structure with the same width as the conductive part 121. The extension part 122 can also be a convex structure provided on one side of the conductive part 121, or other structures.

[0207] In some examples, the conductive member 30 and the electrode lead-out part 2011 can be connected by welding or conductive adhesive, etc., to realize the connection between the conductive member 30 and the electrode lead-out part 2011.

[0208] In some examples, the conductive member 30 is welded to the surface of the extension part 122 facing away from the insulating substrate 11. The large area of the surface of the extension part 122 facing away from the insulating substrate 11 is beneficial to increasing the welding area between the conductive member 30 and the extension part 122, improving the current-carrying area between the conductive member 30 and the extension part 122, being beneficial to improving the current-carrying capacity of the first electrode sheet 1, and being beneficial to improving the fast charging performance of the battery cell 100.

[0209] The trace formed by welding the conductive member 30 to the surface of the extension portion 122 facing away from the insulating substrate 11 is the first welding mark 51. The first welding mark 51 is located at the side of the active material layer 20 along the first direction. Along the first direction, the first welding mark 51 is spaced apart from the active material layer 20, so that the portion of the metal layer 12 not covered by the active material layer 20 is welded to the conductive member 30, and the conductive member 30 will not be welded to the active material layer 20, which is beneficial to reducing the risk of problems such as false soldering and is beneficial to improving the connection reliability and current-carrying capacity between the metal layer 12 and the conductive member 30.

[0210] Along the first direction, the distance between the first welding mark 51 and the active material layer 20 is S1, where 0.3 mm ≤ S1 ≤ 5 mm.

[0211] The design of S1 ≥ 0.3 mm makes there be a distance between the first welding mark 51 and the active material layer 20, so that the conductive member 30 will not be welded to the active material layer 20, reducing the risk of problems such as false soldering; the design of S1 ≤ 5 mm makes the distance between the first welding mark 51 and the active material layer 20 not too large, which is beneficial to increasing the coverage area of the active material layer 20 on the metal layer 12 and is beneficial to improving the energy density of the battery cell 100.

[0212] The value of S1 can be 0.3 mm, 5 mm, and any value between 0.3 mm and 5 mm. Exemplarily, the value of S1 can be but is not limited to 0.3 mm, 0.5 mm, 1 mm, 2 mm, 2.5 mm, 2.8 mm, 3 mm, 4 mm, 5 mm.

[0213] By adopting the technical solution of this embodiment, when the battery cell 100 is in normal use, the electrode lead-out portion 2011 is used to input or output electric energy, realizing the charging and discharging of the battery cell 100; and the design of the distance range between the first welding mark 51 and the active material layer 20 being 0.3 mm to 5 mm makes the first welding mark 51 not be welded to the active material layer 20, reducing problems such as false soldering and being beneficial to improving the connection reliability between the conductive member 30 and the metal layer 12; the distance between the active material layer 20 and the first welding mark 51 is small, and the active material layer 20 can be relatively close to the first welding mark 51. Then, when the size of the metal layer 12 in the first direction is certain, the area that the active material layer 20 can cover is larger, which is beneficial to improving the energy density of the battery cell 100; in addition, the current collector 10 adopts a composite structure of an insulating substrate 11 and a metal layer 12. Compared with the current collector 10 made of pure metal, the thickness of the metal layer 12 is small, and the burrs generated during the production process of the current collector 10 are small, reducing the risk of internal short circuit of the battery cell 100 and being beneficial to improving the use reliability of the battery cell 100; therefore, the battery cell 100 of the embodiment of the present application can better balance the energy density and use reliability.

[0214] In some embodiments, in combination withFigure 7 As shown, the active material layer 20 includes a first active material portion 21 and a second active material portion 22. The first active material portion 21 is connected to the end of the second active material portion 22 facing the extension portion 122, and the thickness of the first active material portion 21 is less than that of the second active material portion 22.

[0215] In some examples, the first active material portion 21 is located at the edge of the active material layer 20 facing the extension portion 122. Both the first active material portion 21 and the second active material portion 22 cover the conductive portion 121. The first active material portion 21 can be generally of an equal-thickness structure, and the thickness of the first active material portion 21 is less than that of the second active material portion 22, such that the first active material portion 21 and the second active material portion 22 form a stepped structure. In other examples, the thickness of the first active material portion 21 can also decrease stepwise, such that the first active material portion 21 is a stepped structure. Or, along the direction of the conductive portion 121 towards the extension portion 122, the thickness of the first active material portion 21 can also decrease slowly, such that the thickness of the first active material portion 21 decreases slowly and the outer shape of the first active material portion 21 is more rounded or smooth.

[0216] During the forming process of the first pole piece 1, the active material layer 20 can be roll-pressed to compact the active material layer 20. The setting of the first active material portion 21 can reduce the roll pressure received by the edge of the active material layer 20 and reduce the risk of cracking at the edge of the active material layer 20.

[0217] In some embodiments, the distance between the first welding mark 51 and the active material layer 20 ranges from 0.5 mm to 2.8 mm.

[0218] It can be understood that 0.5 mm ≤ S1 ≤ 2.8 mm.

[0219] By adopting the technical solution of this embodiment, with the design of 0.5 mm ≤ S1 ≤ 2.8 mm, the distance between the active material layer 20 and the first welding mark 51 is more reasonable, and it can better balance the connection reliability of the conductive member 30 and the energy density of the battery cell 100.

[0220] In some embodiments, the conductive member 30 includes a first connection portion 31 and at least one second connection portion 32. The first connection portion 31 and the second connection portion 32 are arranged along the first direction, the first connection portion 31 and the second connection portion 32 are connected, the second connection portion 32 is connected to the electrode lead-out portion 2011, the first connection portion 31 is welded to the surface of the extension portion 122 facing away from the insulating substrate 11 to form the first welding mark 51, and the second connection portion 32 is located at the side of the extension portion 122 facing away from the conductive portion 121.

[0221] The first connection portion 31 can be the part that guides the welding of the conductive member 30 and the metal layer 12, and the second connection portion 32 can be the part that guides the connection of the conductive member 30 and the electrode lead-out portion 2011.

[0222] In some examples, the first connection portion 31 can cover the extension portion 122 and be welded to the extension portion 122. The second connection portion 32 can be led out from the side of the first connection portion 31 facing away from the active material layer 20 in the first direction to protrude outside the insulating substrate 11, that is, along the thickness direction of the current collector 10. The projection of the first connection portion 31 is located within the projection of the extension portion 122, and the projection of the second connection portion 32 is located outside the projection range of the extension portion 122. In this way, the connection positions of the extension portion 122 and the electrode lead-out portion 2011 on the conductive member 30 are different, which is convenient for connection and can also reduce the mutual influence between the two connections, being beneficial to connection reliability. Of course, in other examples, along the thickness direction of the current collector 10, the projections of the first connection portion 31 and the second connection portion 32 can also partially overlap.

[0223] In some cases, when the electrode sheet is wound to form the electrode assembly 101, the insulating substrate 11 insulates the adjacent two layers of the metal layer 12 from each other, making it difficult for the adjacent two layers of the metal layer 12 to directly connect across the insulating substrate 11 and transmit current outward. As a result, the current can almost only be transmitted outward from the outermost layer of the metal layer 12, resulting in poor conductivity, low fast-charging performance, and easy local overheating, affecting the use reliability of the battery cell 100. However, in the battery cell 100 of the embodiment of the present application, the first connection portion 31 of the conductive member 30 is welded to the extension portion 122, and the second connection portion 32 of the conductive member 30 protrudes outside the insulating substrate 11. In this way, the adjacent two layers of the metal layer 12 can be electrically conducted through the second connection portion 32, thereby breaking the insulation limitation of the insulating substrate 11, effectively improving the conductivity of the first electrode sheet 1, improving the fast-charging performance of the battery cell 100, reducing the heat generation of the battery cell 100, and improving the use reliability of the battery cell 100.

[0224] When forming the electrode assembly 101 by stacking the electrode tabs, the insulating substrate 11 insulates and separates two adjacent metal layers 12 from each other, making it difficult for current to directly pass between the two adjacent metal layers 12 across the insulating substrate 11 and flow outwards. As a result, the current can almost only flow outwards through the outermost metal layer 12, leading to poor conductivity, low fast-charging performance, and easy local overheating, which affects the use reliability of the battery cell 100. In the battery cell 100 of the embodiment of the present application, the first connecting portion 31 of the conductive member 30 is welded to the extending portion 122, and the second connecting portion 32 of the conductive member 30 protrudes outside the insulating substrate 11. In this way, the second connecting portion 32 can electrically connect two adjacent metal layers 12, thereby breaking the insulation limitation of the insulating substrate 11, effectively improving the conductivity of the first electrode tab 1, enhancing the fast-charging performance of the battery cell 100, reducing the heat generation of the battery cell 100, and improving the use reliability of the battery cell 100.

[0225] The first connecting portion 31 is stacked on the surface of the extending portion 122 facing away from the insulating substrate 11 and welded to the surface of the extending portion 122 facing away from the insulating substrate 11. The trace formed by the welding is the first welding mark 51.

[0226] Along the first direction, the first welding mark 51 is spaced apart from the active material layer 20, so that the first connecting portion 31 will not be welded to the active material layer 20, which is beneficial to reducing the risk of problems such as false soldering and improving the connection reliability and current-carrying capacity between the metal layer 12 and the conductive member 30.

[0227] In some examples, the second connecting portion 32 and the electrode lead-out portion 2011 can be connected by direct welding, or can be welded through a conductive member (such as a transfer sheet, etc.). The welding method is convenient for connection and processing and manufacturing. Of course, other connection methods can also be used to achieve the connection.

[0228] By adopting the technical solution of this embodiment, the second connecting portion 32 protrudes outside the extending portion 122, which is convenient for the second connecting portion 32 to be connected to the electrode lead-out portion 2011, and the processing and manufacturing are more convenient.

[0229] In some embodiments, along the first direction, the first welding mark 51 is spaced apart from the end surface of the first connecting portion 31 facing the active material layer 20.

[0230] In some examples, the first electrode tab 1 is a positive electrode tab, and there is a gap between the first welding mark 51 and the active material layer 20. This gap can be used to provide a spaced-apart space between the conductive member 30 and the active material layer 20, so as to reduce the risk of lithium deposition caused by the contact between the conductive member 30 and the active material layer 20. Additionally, it can also provide a spaced-apart space between the first welding mark 51 and the end face of the first connection portion 31 facing the active material layer 20, such that the first welding mark 51 does not extend to the position where the first connection portion 31 faces the active material layer 20, reducing the risk of the end face of the first connection portion 31 facing the active material layer 20 being welded through or cracked, etc., which is beneficial to reducing the burrs generated during welding and is beneficial to improving the service reliability of the battery cell 100.

[0231] In some examples, the first electrode tab 1 is a negative electrode tab, and there is a gap between the first welding mark 51 and the active material layer 20. It can provide a spaced-apart space between the first welding mark 51 and the end face of the first connection portion 31 facing the active material layer 20, such that the second welding mark portion 512 does not extend to the position where the first connection portion 31 faces the active material layer 20, reducing the risk of the end face of the first connection portion 31 facing the active material layer 20 being welded through or cracked, etc., which is beneficial to reducing the burrs generated during welding and is beneficial to improving the service reliability of the battery cell 100; wherein, the conductive member 30 may or may not be in contact with the active material layer 20.

[0232] There is a gap between the first welding mark 51 and the end face of the first connection portion 31 facing the active material layer 20, such that the first welding mark 51 does not extend to the position where the first connection portion 31 faces the active material layer 20, reducing the risk of the end face of the first connection portion 31 facing the active material layer 20 being welded through or cracked, etc., which is beneficial to reducing the burrs generated during welding and is beneficial to improving the service reliability of the battery cell 100.

[0233] In some embodiments, along the first direction, the spacing range between the first welding mark 51 and the end face of the first connection portion 31 facing the active material layer 20 is 0.3 mm to 1.2 mm.

[0234] Along the first direction, the spacing between the first welding mark 51 and the end face of the first connection portion 31 facing the active material layer 20 is S2, where 0.3 mm ≤ S2 ≤ 1.2 mm.

[0235] The design with S2≥1.2mm creates a gap between the first solder mark 51 and the end face of the first connecting part 31 facing the active material layer 20, preventing the first solder mark 51 from extending to the end face of the first connecting part 31 facing the active material layer 20 and reducing the risks such as the end face of the first connecting part 31 facing the active material layer 20 being welded through or cracked. The design with S2≤1.2mm ensures that the gap between the first solder mark 51 and the end face of the first connecting part 31 facing the active material layer 20 is not too large, which is beneficial to increasing the coverage area of the active material layer 20 on the metal layer 12 and improving the energy density of the battery cell 100.

[0236] The value of S2 can be 0.3mm, 1.2mm, or any value between 0.3mm and 1.2mm. For example, the value of S2 can be, but is not limited to, 0.3mm, 0.6mm, 0.8mm, 1mm, 1.2mm.

[0237] By adopting the technical solution of this embodiment, the service reliability and energy density of the battery cell 100 can be better balanced.

[0238] In some embodiments, the first solder mark 51 includes a first solder mark part 511, the extending part 122 includes at least one protruding part 1222, the protruding part 1222 is connected to the conductive part 121, and the first connecting part 31 is welded to the surface of the protruding part 1222 facing away from the insulating substrate 11 to form the first solder mark part 511. Along the second direction, the size l1 of the protruding part 1222 is smaller than the size L1 of the conductive part 121, where the second direction is perpendicular to the first direction and the thickness direction of the current collector 10.

[0239] The protruding part 1222 can refer to a protruding structure at the edge of the metal layer 12, and along the second direction, the size l1 of the protruding part 1222 is smaller than the size L1 of the conductive part 121. The number of the protruding parts 1222 can be one or more.

[0240] In some examples, the protruding part 1222 directly extends outward from the end of the conductive part 121 along the first direction. Alternatively, the extending part 122 further includes a part connecting the conductive part 121 and the protruding part 1222.

[0241] The first connecting part 31 is stacked on the surface of the protruding part 1222 facing away from the insulating substrate 11 and welded to the protruding part 1222, and the trace formed by the welding is the first solder mark part 511.

[0242] In some examples, the first connecting part 31 can be welded to the entire protruding part 1222, or the first connecting part 31 can be welded to a part of the protruding part 1222, and the other part of the first protruding part 1222 is not welded to the first connecting part 31.

[0243] By adopting the technical solution of this embodiment, the first connecting portion 31 and the protruding portion 1222 are connected by welding. The connection method is simple and convenient for the production of the first pole piece 1. In addition, the first connecting portion 31 and the protruding portion 1222 can directly use the first welding mark portion 511 for current conduction, which is beneficial to improving the current-carrying capacity between the first connecting portion 31 and the protruding portion 1222. In addition, along the second direction, the size l1 of the protruding portion 1222 is smaller than the size L1 of the conductive portion 121. The protruding portion 1222 is easily bent with the conductive member 30 and connected to the electrode lead-out portion 2011, which is convenient for processing and production, and is also beneficial to reducing the space occupied after the conductive member 30 is bent, and is beneficial to improving the energy density of the battery cell 100.

[0244] In some embodiments, along the second direction, the first welding mark portion 511 extends from one side edge of the protruding portion 1222 to the other side edge of the protruding portion 1222.

[0245] Along the first direction, the projection of the first welding mark portion 511 falls within the projection of the protruding portion 1222.

[0246] During the production process of the first pole piece 1, the conductive member 30 can be welded to the edge of the equal-length current collector 10 by ultrasonic welding (for example: double-roller continuous ultrasonic welding) or other welding methods to form an equal-width welding mark, and then the conductive member 30 is cut by laser die-cutting or other cutting methods to form a tab for convenient connection to the electrode lead-out portion 2011. During the cutting process, first cut along the second direction between the equal-width welding mark and the active material layer 20, then cut towards the equal-width welding mark until leaving the equal-width welding mark, continue to cut a certain distance away from the active material layer 20, then cut a certain distance along the second direction, and then cut towards the equal-width welding mark until leaving the equal-width welding mark, and then cut along the second direction, so that a first welding mark portion 511 can be obtained. By repeating this cycle, multiple first welding mark portions 511 can be obtained.

[0247] By adopting the technical solution of this embodiment, along the second direction, the first welding mark portion 511 can fill the entire protruding portion 1222. The size L4 of the first welding mark portion 511 along the second direction is large, which is beneficial to increasing the current-carrying area between the first connecting portion 31 and the protruding portion 1222, beneficial to improving the current-carrying capacity between the first connecting portion 31 and the protruding portion 1222, beneficial to reducing the risk of heat generation, and beneficial to improving the fast charging performance and service reliability of the battery cell 100.

[0248] In some embodiments, the protruding portion 1222 includes a first protruding sub-portion 12221 and a second protruding sub-portion 12222. The second protruding sub-portion 12222 is connected between the conductive portion 121 and the first protruding sub-portion 12221. Along the second direction, the dimension l3 of the second protruding sub-portion 12222 is smaller than the dimension l2 of the first protruding sub-portion 12221, and the dimension l2 of the first protruding sub-portion 12221 is smaller than the dimension L1 of the conductive portion 121. The first welding mark portion 511 includes a first welding mark sub-portion 5111. The first connecting portion 31 is welded to the surface of the first protruding sub-portion 12221 facing away from the insulating substrate 11 to form the first welding mark sub-portion 5111.

[0249] Exemplarily, the protruding portion 1222 has a stepped structure. Along the first direction, the protruding portion 1222 is divided into two parts. The part close to the conductive portion 121 is the first protruding sub-portion 12221, and the part away from the conductive portion 121 is the second protruding sub-portion 12222. l2 > l3, which is equivalent to increasing the dimension of the first protruding sub-portion 12221 along the second direction, increasing the current-carrying area between the protruding portion 1222 and the conductive portion 121, improving the current-carrying capacity, and reducing the heat generation of the battery cell 100.

[0250] The first connecting portion 31 is welded to the surface of the first protruding sub-portion 12221 facing away from the insulating substrate 11, and the mark generated by the welding is the first welding mark sub-portion 5111.

[0251] Exemplarily, the first connecting portion 31 can be welded to the side portion of the first protruding sub-portion 12221 facing the conductive portion 121, so that the first welding mark sub-portion 5111 is directly connected to the conductive portion 121. In this way, the first connecting portion 31 and the conductive portion 121 can directly conduct current through the first welding mark portion 5111, which is beneficial to improving the current-carrying capacity between the first connecting portion 31 and the conductive portion 121, reducing the heat generation of the battery cell 100, and improving the fast charging performance and service reliability of the battery cell 100. Of course, the first connecting portion 31 can also be welded to the side portion of the first protruding sub-portion 12221 facing away from the conductive portion 121, so that the first welding mark sub-portion 5111 is spaced from the conductive portion 121.

[0252] By adopting the technical solution of this embodiment, the first connecting portion 31 is welded to the first protruding sub-portion 12221 to form the first welding mark sub-portion 5111. The dimension of the first protruding sub-portion 12221 along the second direction is large, which is beneficial to increasing the welding area between the protruding portion 1222 and the first connecting portion 31, increasing the current-carrying area between the protruding portion 1222 and the first connecting portion 31, improving the current-carrying capacity, reducing the heat generation of the battery cell 100, and being beneficial to improving the fast charging performance and service reliability of the battery cell 100. In addition, along the second direction, the dimension l3 of the second protruding sub-portion 12222 is small, which is beneficial to reducing the occupied space of the protruding portion 1222 and beneficial to improving the energy density of the battery cell 100.

[0253] In some embodiments, along the second direction, the first welding mark sub - portion 5111 extends from one side edge of the first protruding sub - portion 12221 to the other side edge of the first protruding sub - portion 12221.

[0254] Along the first direction, the projection of the first welding mark sub - portion 5111 falls within the projection of the first protruding sub - portion 12221.

[0255] By adopting the technical solution of this embodiment, along the second direction, the size of the first welding mark sub - portion 5111 is large, which is beneficial to increasing the welding area between the protruding portion 1222 and the first connecting portion 31, increasing the current - carrying area between the protruding portion 1222 and the first connecting portion 31, improving the current - carrying capacity, reducing the heat generation of the battery cell 100, and being beneficial to improving the fast - charging performance and service reliability of the battery cell 100.

[0256] In some embodiments, the first welding mark portion 511 further includes a second welding mark sub - portion 5112. The first connecting portion 31 is welded to the surface of the second protruding sub - portion 12222 facing away from the insulating substrate 11 to form the second welding mark sub - portion 5112.

[0257] Exemplarily, the surface of the second protruding sub - portion 12222 facing away from the insulating substrate 11 is welded to the first connecting portion 31, and the trace generated by the welding is the second welding mark sub - portion 5112.

[0258] By adopting the technical solution of this embodiment, the second protruding sub - portion 12222 is also welded to the first connecting portion 31, which is beneficial to increasing the current - carrying area between the first connecting portion 31 and the protruding portion 1222 and is beneficial to improving the current - carrying capacity between the first connecting portion 31 and the protruding portion 1222.

[0259] In some embodiments, along the second direction, the second welding mark sub - portion 5112 extends from one side edge of the second protruding sub - portion 12222 to the other side edge of the second protruding sub - portion 12222.

[0260] Along the first direction, the projection of the second welding mark sub - portion 5112 falls within the projection of the second protruding sub - portion 12222.

[0261] By adopting the technical solution of this embodiment, the size of the second welding mark sub - portion 5112 along the second direction is large, which is beneficial to increasing the welding area between the first connecting portion 31 and the protruding portion 1222, increasing the current - carrying area between the first connecting portion 31 and the protruding portion 1222, and being beneficial to improving the current - carrying capacity between the first connecting portion 31 and the protruding portion 1222.

[0262] Please refer to Figures 11 - 17As shown, in some embodiments, the first solder mark 51 includes a second solder mark portion 512. The extension portion 122 further includes a transition portion 1221. The transition portion 1221 is connected between the protruding portion 1222 and the conductive portion 121. The first connecting portion 31 is welded to the surface of the transition portion 1221 facing away from the insulating substrate 11 and forms the second solder mark portion 512. Along the second direction, the dimension L2 of the transition portion 1221 is greater than the sum of the dimensions l1 of all the protruding portions 1222, where the second direction is perpendicular to the first direction and the thickness direction of the current collector 10.

[0263] Exemplarily, along the first direction, the extension portion 122 is divided into two parts. The part close to the conductive portion 121 is the transition portion 1221, and the part away from the conductive portion 121 is the conductive portion 121. The protruding portion 1222 protrudes away from the conductive portion 121 from the edge of the transition portion 1221 away from the conductive portion 121. The conductive portion 121 is covered with the active material layer 20, and neither the transition portion 1221 nor the protruding portion 1222 is covered with the active material layer 20 to facilitate connection with the first connecting portion 31.

[0264] In some examples, the protruding portion 1222 extends outward along the first direction from the side portion of the transition portion 1221 facing away from the conductive portion 121. Along the second direction, the dimension of the protruding portion 1222 may be equal to the dimension of the transition portion 1221, or, along the second direction, the sum of the dimensions l2 of all the first protruding sub-portions 12221 of the protruding portions 1222 is less than or equal to the dimension L2 of the transition portion 1221.

[0265] The first connecting portion 31 is welded to the surface of the transition portion 1221 facing away from the insulating substrate 11, and the trace generated by the welding of the transition portion 1221 and the first connecting portion 31 is the second solder mark portion 512.

[0266] In some examples, the first solder mark 51 includes a second solder mark portion 512 and a first solder mark portion 511. The first solder mark portion 511 is located between the second solder mark portion 512 and the active material layer 20, that is, the first connecting portion 31 welds the transition portion 1221 and the protruding portion 1222 simultaneously.

[0267] In some examples, the first solder mark 51 includes a second solder mark portion 512. The first connecting portion 31 is only welded to the transition portion 1221 and not to the protruding portion 1222.

[0268] In some examples, the first solder mark 51 may only include the first solder mark portion 511, that is, the first connecting portion 31 is welded to the protruding portion 1222 and not to the transition portion 1221.

[0269] Along the second direction, the dimension L2 of the transition portion 1221 is greater than the sum of the dimensions l1 of all the protruding portions 1222, where the second direction is perpendicular to the first direction and the thickness direction of the current collector 10.

[0270] By adopting the technical solution of this embodiment, the surface of the transition part 1221 facing away from the insulating substrate 11 is welded to the first connection part 31, so that a part of the current can flow directly into or out of the first connection part 31 through the transition part 1221, reducing the overcurrent pressure between the protruding part 1222 and the transition part 1221, which is beneficial to reducing the heat generation at the connection between the protruding part 1222 and the transition part 1221; in addition, the first connection part 31 and the transition part 1221 are connected by welding, and the connection method is simple, which is beneficial to facilitating the production of the first pole piece 1; the second welding mark part 512 can be directly used for overcurrent between the first connection part 31 and the transition part 1221, which is beneficial to improving the overcurrent capacity between the first connection part 31 and the transition part 1221 and reducing the heat generation of the battery cell 100.

[0271] In some embodiments, along the second direction, the size of the conductive part 121 is L1, and the size of the transition part 1221 is L2, where 0.8 ≤ L2 / L1 ≤ 1.

[0272] 0.8 ≤ L2 / L1 ≤ 1. Along the second direction, the size L2 of the transition part 1221 is less than or equal to the size L1 of the conductive part 121, and the size L2 of the transition part 1221 is greater than or equal to 0.8 times the size L1 of the conductive part 121. The larger the size L2 of the transition part 1221, the larger the connection area between the transition part 1221 and the first connection part 31 can be set, and the better the overcurrent capacity between the transition part 1221 and the first connection part 31.

[0273] In some examples, 0.8 ≤ L2 / L1 < 1. Along the second direction, the transition part 1221 can be located at the middle position of the conductive part 121, and the two ends of the transition part 1221 are not flush with the conductive part 121.

[0274] In some examples, 0.8 ≤ L2 / L1 < 1. Along the second direction, the transition part 1221 can also be arranged to be biased towards one end of the conductive part 121, so that one end of the transition part 1221 is flush with the conductive part 121 and the other end is not flush, or neither end is flush. The value of L2 / L1 can be but is not limited to 0.8, 1 or any value between 0.8 and 1. Exemplarily, the value of L2 / L1 can be but is not limited to 0.8, 0.85, 0.9, 0.95, 1.

[0275] By adopting the technical solution of this embodiment, the design of 0.8 ≤ L2 / L1 ≤ 1 makes the size of the transition part 1221 along the second direction large, which is beneficial to increasing the connection area between the first connection part 31 and the transition part 1221, improving the overcurrent capacity at the connection between the first connection part 31 and the transition part 1221, improving the overcurrent capacity of the first pole piece 1, reducing the heat generation of the battery cell 100, and improving the fast charging performance of the battery cell 100.

[0276] In some embodiments, L2 = L1.

[0277] L2 / L1 = 1. Along the second direction, the dimension L2 of the transition portion 1221 is equal to the dimension L1 of the conductive portion 121. At both ends of the transition portion 1221 along the second direction, it is flush with the conductive portion 121. The transition portion 1221 and the conductive portion 121 have an equal-length structure.

[0278] By adopting the technical solution of this embodiment, the design of L2 = L1 makes the dimension of the transition portion 1221 along the second direction relatively large, which is beneficial to designing a relatively large connection area between the first connection portion 31 and the transition portion 1221. The current-carrying capacity at the connection between the first connection portion 31 and the transition portion 1221 is the best, which can effectively improve the current-carrying capacity of the first electrode tab 1, reduce the heat generation of the battery cell 100, and improve the fast-charging performance of the battery cell 100.

[0279] In some embodiments, the first welding mark 51 may only be the first welding mark portion 511, that is, the first connection portion 31 is welded to the protruding portion 1222, but not to the transition portion 1221.

[0280] In some embodiments, along the second direction, the dimension L2 of the transition portion 1221 is L2, and the dimension L3 of the second welding mark portion 512 is L3, where 0.8 ≤ L3 / L2 ≤ 1.

[0281] 0.8 ≤ L3 / L2 ≤ 1. Along the second direction, the dimension L3 of the second welding mark portion 512 may be less than or equal to the dimension L2 of the transition portion 1221. The dimension L3 of the second welding mark portion 512 is greater than or equal to 0.8 times the dimension L2 of the transition portion 1221. The dimension L3 of the second welding mark portion 512 exceeds more than half of the dimension L2 of the transition portion 1221. The longer the dimension L3 of the second welding mark portion 512, the larger the welding area between the transition portion 1221 and the first connection portion 31, and the better the current-carrying capacity at the connection between the transition portion 1221 and the first connection portion 31.

[0282] In some examples, 0.8 ≤ L3 / L2 < 1. Along the second direction, the second welding mark portion 512 may be located at the middle position of the transition portion 1221, and both ends of the second welding mark portion 512 are not flush with the transition portion 1221.

[0283] In some examples, 0.8 ≤ L2 / L1 < 1. Along the second direction, the second welding mark portion 512 may also be disposed to be biased towards one end of the transition portion 1221, such that one end of the transition portion 1221 is flush with the transition portion 1221, the other end is not flush, or both ends are not flush.

[0284] The value of L3 / L2 can be, but is not limited to, 0.8, 1, or any value between 0.8 and 1. Exemplarily, the value of L3 / L2 can be, but is not limited to, 0.8, 0.85, 0.9, 0.95, 1.

[0285] By adopting the technical solution of this embodiment, the design of 0.8 ≤ L3 / L2 ≤ 1 makes the size of the transition portion 1221 in the second direction relatively large, which is beneficial to increasing the connection area between the first connection portion 31 and the transition portion 1221, improving the current-carrying capacity at the connection between the first connection portion 31 and the transition portion 1221, enhancing the current-carrying capacity of the first pole piece 1, reducing the heat generation of the battery cell 100, and improving the fast charging performance of the battery cell 100.

[0286] In some embodiments, L3 = L2.

[0287] L3 / L2 = 1. Along the second direction, the size L3 of the second welding mark portion 512 is equal to the size L2 of the transition portion 1221, and both ends of the second welding mark portion 512 are flush with the transition portion 1221.

[0288] In some examples, the protruding portion 1222 and the transition portion 1221 are simultaneously welded to the first connection portion 31 to form the entire welding mark. Welding the first connection portion 31 to the transition portion 1221 can effectively increase the welding area between the first connection portion 31 and the metal layer 12, improve the current-carrying area between the first connection portion 31 and the metal layer 12, and is beneficial to enhancing the current-carrying capacity between the first connection portion 31 and the metal layer 12.

[0289] During the process of cutting the conductive member 30, first cut along the second direction on the equal-width welding mark, then cut in the direction away from the active material layer 20 until leaving the equal-width welding mark, continue to cut a certain distance in the direction away from the active material layer 20, then cut a certain distance along the second direction, then cut in the direction towards the active material layer 20 until cutting a certain distance of the equal-width welding mark, and then continue to cut along the second direction on the equal-width welding mark, and so on in a cyclic manner, then the first welding mark 51 can be obtained; wherein, taking the cutting position along the second direction on the equal-width welding mark as a reference, along the first direction, the part of the first welding mark 51 located on the side of the cutting position towards the active material layer 20 is the second welding mark portion 512, and the part located on the side of the cutting position away from the active material layer 20 is the first welding mark portion 511. The first welding mark portion 511 can be a protruding structure of the second welding mark portion 512 away from the active material layer 20; and after cutting is completed, during the cutting process from the direction away from the active material layer 20 to the direction towards the active material layer 20, the metal layer 12 of the current collector 10 cuts out the protruding portion 1222, and during the cutting process along the second direction, the part located between the protruding portion 1222 and the active material layer 20 forms the transition portion 1221.

[0290] By adopting the technical solution of this embodiment, the design of L3 / L2 = 1 makes the size of the second welding mark portion 512 in the second direction relatively large, which is conducive to designing a relatively large welding area between the first connecting portion 31 and the transition portion 1221. The current-carrying capacity at the connection between the first connecting portion 31 and the transition portion 1221 is the best, which can effectively improve the current-carrying capacity of the first pole piece 1, reduce the heat generation of the battery cell 100, and improve the fast charging performance of the battery cell 100.

[0291] In some embodiments, along the second direction, the size L4 of the first welding mark portion 511 is smaller than the size L3 of the second welding mark portion 512.

[0292] By adopting the technical solution of this embodiment, along the second direction, the size L3 of the second welding mark portion 512 is large, and the welding area between the transition portion 1221 and the first connecting portion 31 is large, which is conducive to improving the current-carrying capacity of the first connecting portion 31 and the transition portion 1221, and is conducive to improving the fast charging performance and use reliability of the battery cell 100.

[0293] In some embodiments, the number of the protruding portions 1222 is multiple, and the multiple protruding portions 1222 are arranged at intervals along the second direction. Each protruding portion 1222 is welded to the first connecting portion 31, and the second direction is perpendicular to the first direction and the thickness direction of the current collector 10.

[0294] The number of the protruding portions 1222 is multiple, for example: two, three, four, etc.; the multiple protruding portions 1222 are arranged at intervals along the second direction.

[0295] After the first pole piece 1 is wound or stacked, the multiple protruding portions 1222 are stacked together, and at the same time, the multiple second connecting portions 32 are also stacked together, thereby breaking the insulation limitation of the insulating matrix 11, which can effectively improve the conductivity of the first pole piece 1, improve the fast charging performance of the battery cell 100, reduce the heat generation of the battery cell 100, and improve the use reliability of the battery cell 100, the metal layer 12.

[0296] The multiple protruding portions 1222 are arranged at intervals along the second direction, so that along the second direction, the sum of the sizes l1 of all the protruding portions 1222 is smaller than the size L2 of the transition portion 1221, and along the second direction, the sum of the sizes L4 of all the first welding mark portions 511 is smaller than the size L3 of the second welding mark portion 512. The large size L3 of the second welding mark portion 512 is conducive to increasing the welding area between the transition portion 1221 and the first connecting portion 31, conducive to improving the current-carrying capacity at the connection between the transition portion 1221 and the conductive member 30, conducive to improving the current-carrying capacity of the first pole piece 1, reducing the heat generation of the battery cell 100, and improving the fast charging performance and use reliability of the battery cell 100.

[0297] Among the multiple first welding imprint parts 511, along the second direction, the size L4 of some of the first welding imprint parts 511 may be the same, or the sizes L4 of all the first welding imprint parts 511 may be completely different, or the sizes L4 of all the first welding imprint parts 511 may be the same.

[0298] By adopting the technical solution of this embodiment, the multiple protruding parts 1222 are arranged at intervals along the second direction, which is beneficial to dividing the conductive part 121 into multiple regions along the second direction, and one region can correspond to one protruding part 1222. The electrons in each region can be transmitted to the electrode lead-out part 2011 through the corresponding protruding part 1222, so that the electrons of the conductive part 121 are transmitted in sub-regions. The electron transmission path in each region to the corresponding protruding part 1222 is short, which is beneficial to reducing the electron transmission distance, reducing the overall resistance of the first electrode sheet 1, and improving the fast charging performance and use reliability of the battery cell 100.

[0299] In some embodiments, the first connecting part 31 includes multiple first connecting sub-parts 311, the multiple first connecting sub-parts 311 are arranged at intervals along the second direction, the number of the second connecting parts 32 is multiple, and each first connecting sub-part 311 is connected to each second connecting part 32 in one-to-one correspondence; each first connecting sub-part 311 is welded to the surface of each protruding part 1222 facing away from the insulating substrate 11.

[0300] The first connecting sub-part 311 may refer to the part of the first connecting part 31 covering the protruding part 1222; the number of the first connecting sub-parts 311, the number of the second connecting parts 32, and the number of the protruding parts 1222 are the same. One first connecting sub-part 311 corresponds to one protruding part 1222, one first connecting sub-part 311 is connected to one second connecting part 32, and one first connecting sub-part 311 is welded to one protruding part 1222 to form a first welding imprint part 511.

[0301] By adopting the technical solution of this embodiment, the multiple first connecting sub-parts 311 of the first connecting part 31 are arranged at intervals along the second direction, and there is a gap between two adjacent first connecting sub-parts 311, which can reduce the material required for the first connecting part 31 and reduce the manufacturing cost of the battery cell 100.

[0302] In some embodiments, the number of the protruding portions 1222 is plural, the plural protruding portions 1222 are arranged at intervals in a second direction perpendicular to the first direction and the thickness direction of the current collector 10; the first connecting portion 31 includes a second connecting sub-portion 312 and plural first connecting sub-portions 311, the plural first connecting sub-portions 311 are arranged at intervals in the second direction, and each first connecting sub-portion 311 is welded to the surface of each protruding portion 1222 facing away from the insulating substrate 11; the number of the second connecting portions 32 is plural, and along the first direction, one side of each first connecting sub-portion 311 is connected to each second connecting portion 32 in a one-to-one correspondence, and the other side of each first connecting sub-portion 311 is connected to the second connecting sub-portion 312, and the second connecting sub-portion 312 is continuously arranged in the second direction; the second connecting sub-portion 312 is welded to the surface of the transition portion 1221 facing away from the insulating substrate 11.

[0303] The second connecting sub-portion 312 may refer to the portion of the first connecting portion 31 covering the transition portion 1221; the second connecting sub-portion 312 is continuously arranged in the second direction. Exemplarily, along the second direction, the second connecting sub-portion 312 extends from one side edge of the transition portion 1221 to the other side of the transition portion 1221.

[0304] The second connecting sub-portion 312 is welded to the surface of the transition portion 1221 facing away from the insulating substrate 11 to form a second welding mark portion 512.

[0305] By adopting the technical solution of this embodiment, the second connecting sub-portion 312 is continuously arranged in the second direction, and the plural first connecting sub-portions 311 can be connected into a whole. The second connecting sub-portion 312 can play a good supporting role for the first connecting sub-portions 311, and can reduce the risk of the first connecting sub-portions 311 being bent when inserted between the first pole piece 1 and the second pole piece 2, reduce the short-circuit risk, and is beneficial to improving the use reliability of the battery cell 100; in addition, along the second direction, the size of the second connecting sub-portion 312 is large, which is beneficial to increasing the welding area between the second connecting sub-portion 312 and the transition portion 1221, beneficial to improving the current-carrying capacity at the connection between the first connecting portion 31 and the transition portion 1221, improving the current-carrying capacity of the first pole piece 1, and improving the fast-charging performance and use reliability of the battery cell 100.

[0306] In some embodiments, along the second direction, the sum of the sizes L4 of all the first welding mark portions 511 is less than the size L3 of the second welding mark portion 512.

[0307] By adopting the technical solution of this embodiment, along the second direction, the sum of the dimensions L4 of all the first welding imprints 511 is less than the dimension L3 of the second welding imprint 512. The large dimension L3 of the second welding imprint 512 is conducive to increasing the welding area between the transition portion 1221 and the first connecting portion 31, conducive to increasing the current-carrying capacity at the connection between the transition portion 1221 and the conductive member 30, conducive to increasing the current-carrying capacity of the first electrode tab 1, reducing the heat generation of the battery cell 100, and improving the fast charging performance and service reliability of the battery cell 100.

[0308] In some examples, the second welding imprint 512 and the first welding imprint 511 are directly connected.

[0309] The second welding imprint 512 and the first welding imprint 511 form an integral first welding imprint 51, and there is no obvious demarcation line between them; the integral first welding imprint 51 can cover the junction of the protruding portion 1222 and the transition portion 1221; in the actual manufacturing process, the second welding imprint 512 and the first welding imprint 511 are formed by cutting the equal-width welding imprints as described above.

[0310] In some examples, the second welding imprint 512 and the first welding imprint 511 adopt the structural form of solder joints, and the pitch of the solder joints in the second welding imprint 512 is the same as the pitch of the solder joints in the first welding imprint 511; for example: the solder joints in the second welding imprint 512 and the first welding imprint 511 are not welded to the junction line of the protruding portion 1222 and the transition portion 1221, and the distance between two adjacent solder joints in the second welding imprint 512 and the first welding imprint 511 is equal to the pitch of the solder joints in the second welding imprint 512; for example, the solder joints are welded to the junction line of the protruding portion 1222 and the transition portion 1221, thereby connecting the second welding imprint 512 and the first welding imprint 511 into an integral welding imprint.

[0311] By adopting the technical solution of this embodiment, the first welding imprint 51 can cover the junction of the protruding portion 1222 and the transition portion 1221, and a part of the current can directly flow through the transition portion 1221 to the first connecting portion 31, reducing the current-carrying pressure at the junction of the protruding portion 1222 and the transition portion 1221, conducive to increasing the current-carrying capacity of the first electrode tab 1, reducing the heat generation of the battery cell 100, and conducive to improving the fast charging performance of the battery cell 100.

[0312] In some embodiments, along the first direction, the first connecting portion 31 and the active material layer 20 are spaced apart.

[0313] The first connecting portion 31 and the active material layer 20 do not directly contact each other, but there is a certain gap therebetween, such that the first connecting portion 31 does not contact the active material layer 20.

[0314] In some examples, the first electrode tab 1 is a positive electrode tab, and the first connecting portion 31 does not contact the active material layer 20, which can reduce risks such as lithium plating and is beneficial to improving the usage reliability of the battery cell 100. In other examples, the first electrode tab 1 is a negative electrode tab, and the first connecting portion 31 may or may not contact the active material layer 20.

[0315] By adopting the technical solution of this embodiment, the first connecting portion 31 does not contact the active species layer, which can reduce the mutual influence between the two and improve the usage reliability of the battery cell 100.

[0316] In some embodiments, the electrode assembly 101 further includes an insulating member 40. The insulating member 40 includes a first insulating portion 41. The first insulating portion 41 covers the surface of the extending portion 122 facing away from the insulating substrate 11, and the entire first insulating portion 41 is located between the first welding mark 51 and the active material layer 20.

[0317] The insulating member 40 may refer to a component capable of insulating. The insulating member 40 includes a first insulating portion 41. The first insulating portion 41 may refer to an insulating component covering the surface of the extending portion 122 facing away from the active material layer 20; the first insulating portion 41 may be, but is not limited to, an insulating coating, insulating glue (such as: hot melt glue) or insulating tape.

[0318] In the thickness direction of the current collector 10, the first insulating portion 41 does not coincide with the first welding mark 51, and the first insulating portion 41 is spaced from the first welding mark 51, so that the first connecting portion 31 will not be welded to the first insulating portion 41, which is beneficial to reducing the risk of virtual soldering between the first connecting portion 31 and the extending portion 122; or, the first insulating portion 41 coincides with the first welding mark 51 only at the edge, and the edge of the first welding mark 51 coincides with the edge of the first insulating portion 41, which can also reduce the risk of virtual soldering between the first connecting portion 31 and the metal layer 12.

[0319] By adopting the technical solution of this embodiment, it is beneficial to reduce the risk of virtual soldering between the first connecting portion 31 and the extending portion 122, which is beneficial to reducing the risk of virtual soldering between the first connecting portion 31 and the extending portion 122, improving the connection reliability between the first connecting portion 31 and the extending portion 122, and also beneficial to improving the overcurrent capacity.

[0320] In some embodiments, the first insulating portion 41 is located between the first connecting portion 31 and the active material layer 20.

[0321] In some examples, the entire first insulating portion 41 is located between the first connecting portion 31 and the active material layer 20.

[0322] In some examples, when the first connecting portion 31 is only welded to the protruding portion 1222 and the first connecting portion 31 is spaced apart from the transition portion 1221, a part of the first insulating portion 41 covers the first protruding sub-portion 12221, and the other part covers the transition portion 1221. Such a setting can fully cover the portion of the metal layer 12 between the first connecting portion 31 and the active material layer 20. At the same time, it can also support the root of the protruding portion 1222, and can reduce damages such as cracks and fractures that occur at the root of the protruding portion 1222 during the manufacturing process of the battery device 1100, which is beneficial to improving the electron transmission ability of the root of the protruding portion 1222 and improving the fast charging performance and service reliability of the battery cell 100. Of course, in other examples, the first insulating portion 41 can only cover the transition portion 1221.

[0323] In some examples, when both the protruding portion 1222 and the transition portion 1221 are welded to the first connecting portion 31, the first insulating portion 41 covers the transition portion 1221.

[0324] By adopting the technical solution of this embodiment, the first insulating portion 41 can support the portion of the extending portion 122 between the first connecting portion 31 and the active material layer 20, and can reduce damages such as cracks and fractures that occur in this portion during the manufacturing process of the battery device 1100, which is beneficial to improving the electron transmission ability of this portion and improving the fast charging performance and service reliability of the battery cell 100. In addition, the first insulating portion 41 can also insulate this portion, reduce the short-circuit risk of the battery cell 100, and improve the service reliability of the battery cell 100.

[0325] In some embodiments, the insulating member 40 further includes a second insulating portion 42, and at least a part of the second insulating portion 42 covers the first welding mark 51.

[0326] The second insulating portion 42 covers the surface of the first connecting portion 31 facing away from the extending portion 122 and covers at least a part of the first welding mark 51. Among them, the second insulating portion 42 can cover a part of the first welding mark 51 or the entire first welding mark 51. The second insulating portion 42 can be, but is not limited to, an insulating coating, an insulating adhesive (for example: hot melt adhesive), or an insulating tape. The first insulating portion 41 and the second insulating portion 42 can be an integrally formed structure or two separate components connected.

[0327] A part of the second insulating portion 42 can cover the first welding mark 51, and the other part covers the first insulating portion 41 or the active material layer 20, or the entire second insulating portion 42 covers the first welding mark 51.

[0328] In some examples, the first welding mark 51 includes a first welding mark portion 511, and the second insulating portion 42 covers at least a part of the first welding mark portion 511. The second insulating portion 42 may cover a part of the first welding mark portion 511 or may cover the entire first welding mark portion 511.

[0329] In some examples, the first welding mark 51 includes a second welding mark portion 512 and a first welding mark portion 511, and the second insulating portion 42 covers the second welding mark portion 512 and the first welding mark portion 511.

[0330] After the first connecting portion 31 is welded to the extending portion 122, components such as tip protrusions and metal debris are likely to be generated on the surface of the first welding mark 51. In the embodiment of the present application, the second insulating portion 42 covers the surface of the first welding mark 51, which can prevent components such as tip protrusions and metal debris on the surface of the first welding mark 51 from piercing through the separator 3 and connecting to the second pole piece 2, reducing the short-circuit risk of the battery cell 100 and improving the use reliability of the battery cell 100.

[0331] In some embodiments, along the direction from the conductive portion 121 to the extending portion 122, the second insulating portion 42 protrudes from the end face of the first protruding sub-portion 12221 facing away from the conductive portion 121.

[0332] Along the thickness direction of the current collector 10, the projection of the end face of the first protruding sub-portion 12221 facing away from the conductive portion 121 falls within the projection of the second insulating portion 42.

[0333] In some examples, during the manufacturing process of the pole piece, the end face of the first protruding sub-portion 12221 facing away from the conductive portion 121 is obtained by cutting, resulting in burrs being easily generated on the end face of the first protruding sub-portion 12221 facing away from the conductive portion 121. The second insulating portion 42 can block the burrs at the end face of the first protruding sub-portion 12221 facing away from the conductive portion 121, reducing the short-circuit risk inside the battery cell 100 and being beneficial to improving the use reliability of the battery cell 100. In addition, the second insulating portion 42 can completely cover the first welding mark sub-portion 5111, reducing the risk of short circuit caused by components such as tip protrusions and metal debris on the first welding mark sub-portion 5111, and being beneficial to improving the use reliability of the battery cell 100.

[0334] In some embodiments, along the direction from the conductive portion 121 to the extending portion 122, the second insulating portion 42 protrudes from the edge of the second welding mark sub-portion 5112 facing away from the first protruding sub-portion 12221.

[0335] Along the thickness direction of the current collector 10, the projection of the edge of the second welding mark sub-portion 5112 facing away from the first protruding sub-portion 12221 falls within the projection of the second insulating portion 42, so that the second insulating portion 42 can completely cover the second welding mark sub-portion 5112 and the first welding mark sub-portion 5111.

[0336] During the production process of the electrode tab, the second insulating portion 42 can completely cover the second welding mark sub-portion 5112 and the first welding mark sub-portion 5111, reducing the risk of short circuit caused by components such as tip protrusions and metal debris on the second welding mark sub-portion 5112 and the first welding mark sub-portion 5111, which is beneficial to improving the usage reliability of the battery cell 100.

[0337] In some embodiments, along the first direction, one side of the second insulating portion 42 covers the first welding mark 51, and the other side of the second insulating portion 42 covers at least a partial area of the first insulating portion 41.

[0338] It can be understood that among the opposite two sides of the second insulating portion 42 along the first direction, one side covers the first welding mark 51, and the other side can cover the entire first insulating portion 41, or can cover a part of the first insulating portion 41, and even cover the active material layer 20.

[0339] Along the first direction, the second insulating portion 42 extends from the first welding mark 51 to the first insulating portion 41; or, the second insulating portion 42 extends from the first welding mark 51 to the active material layer 20, thereby completely covering the first insulating portion 41.

[0340] By adopting the technical solution of this embodiment, the second insulating portion 42 and the first insulating portion 41 jointly cover the extension portion 122, which can achieve double-layer insulation, is beneficial to reducing the short-circuit risk of the battery cell 100, and is beneficial to improving the usage reliability of the battery cell 100.

[0341] In some embodiments, the electrode assembly 101 further includes an insulating member 40, the insulating member 40 includes a second insulating portion 42, and at least a part of the second insulating portion 42 covers the first welding mark 51.

[0342] It can be understood that the insulating member 40 includes a second insulating portion 42, the insulating member 40 may not include the first insulating portion 41, or the insulating member 40 may include the first insulating portion 41 and the second insulating portion 42.

[0343] By adopting the technical solution of this embodiment, the second insulating portion 42 covers the surface of the first welding mark 51, which can prevent components such as burrs and metal debris on the surface of the first welding mark 51 from piercing through the separator 3 and connecting with the second electrode tab 2, reducing the short-circuit risk of the battery cell 100 and improving the usage reliability of the battery cell 100.

[0344] Please refer to Figures 18 - 21 As shown, in some embodiments, along the first direction, one side of the second insulating portion 42 covers the first welding mark 51, and the other side of the second insulating portion 42 covers at least a part of the active material layer 20.

[0345] It can be understood that among the two sides of the second insulating portion 42 that are distributed relatively along the first direction, one side covers the first welding mark 51, and the other side covers at least a partial area of the active material layer 20. Herein, the second insulating portion 42 can cover the end portion of the active material layer 20 facing the first connecting portion 31, or can also cover the entire active material layer 20.

[0346] Along the first direction, the second insulating portion 42 extends from the first welding mark 51 to the active material layer 20, so that the portion of the metal layer 12 and the first connecting portion 31 located between the first welding mark 51 and the active material layer 20 is covered. Herein, a first insulating portion 41 can be provided between the second insulating portion 42 and the metal layer 12, or the first insulating portion 41 can also not be provided.

[0347] In some examples, the metal layer 12 is covered with the first insulating portion 41. After the second insulating portion 42 completely covers the first insulating portion 41, it can further extend onto the active material layer 20 to cover the active material layer 20. The metal layer 12 is covered with the first insulating portion 41 and the second insulating portion 42, achieving two - layer insulation with good insulation effect.

[0348] In some examples, the metal layer 12 is not covered with the first insulating portion 41. The second insulating portion 42 extends from the first welding mark 51 to the active material layer 20. In this way, the portion of the metal layer 12 located between the first connecting portion 31 and the active material layer 20 can be covered, reducing the risk of short - circuit in this part, which is beneficial to improving the use reliability of the battery cell 100. In addition, the first insulating portion 41 can be omitted, saving costs. At the same time, the active material layer 20 can be used to cover the original position of the first insulating portion 41, which can increase the covering area of the active material layer 20 on the metal layer 12, being beneficial to improving the energy density of the battery cell 100.

[0349] By adopting the technical solution of this embodiment, the second insulating portion 42 extends from the first welding mark 51 to the active material layer 20. The second insulating portion 42 has a wide covering area and good insulation effect, which is beneficial to improving the use reliability of the battery cell 100.

[0350] In some embodiments, along the first direction, the size of the portion of the insulating member 40 covering the active material layer 20 is H, where 0.2 mm ≤ H ≤ 1.0 mm. Optionally, 0.3 mm ≤ H ≤ 0.8 mm.

[0351] In some examples, the value of H can be 0.2 mm, 1 mm, or any value between 0.2 mm and 1.0 mm. Exemplarily, the value of H can be, but is not limited to, 0.2 mm, 0.3 mm, 0.4 mm, 0.6 mm, 0.8 mm, 0.9 mm, 1 mm.

[0352] The design with H≥0.2 mm enables the insulating member 40 to cover the end of the active material layer 20 facing the extension portion 122. The insulating member 40 can block the burrs at the end of the active material layer 20 facing the extension portion 122, improving the usage reliability of the battery cell 100. The design with H≤1.0 mm makes the part of the insulating member 40 covering the active material layer 20 not too large, which is beneficial to reducing the weight and volume of the insulating member 40 and improving the energy density of the battery cell 100.

[0353] In some examples, the insulating member 40 includes a first insulating portion 41. The first insulating portion 41 covers the end of the active material layer 20 facing the protruding portion 1222. The part of the first insulating portion 41 covering the active material layer 20 may refer to the mutually soluble region formed by the first insulating portion 41 and the active material layer 20, so that the fixation of the first insulating portion 41 is more stable.

[0354] In some examples, the insulating member 40 includes a second insulating portion 42. The second insulating portion 42 covers the end of the active material layer 20 facing the extension portion 122.

[0355] By adopting the technical solution of this embodiment, along the first direction, the size of the part of the second insulating portion 42 covering the active material layer 20 is reasonable, and it can take into account both blocking the burrs at the end of the conductive portion 121 facing the extension portion 122 and the energy density of the battery cell 100.

[0356] In some embodiments, 0.3 mm≤H≤0.8 mm.

[0357] By adopting the technical solution of this embodiment, along the first direction, the size of the part of the second insulating portion 42 covering the active material layer 20 is more reasonable, and it can better take into account both blocking the burrs at the end of the conductive portion 121 facing the protruding portion 1222 and the energy density problem of the battery cell 100.

[0358] In some embodiments, along the direction from the conductive portion 121 to the protruding portion 1222, the second insulating portion 42 protrudes from the end face of the first protruding sub-portion 12221 facing away from the conductive portion 121.

[0359] Along the thickness direction of the current collector 10, the projection of the end face of the first protruding sub-portion 12221 facing away from the conductive portion 121 falls within the projection of the second insulating portion 42.

[0360] During the production process of the electrode, the end face of the first protruding sub - part 12221 facing away from the conductive part 121 is obtained by cutting, which makes it easy for burrs to occur on the end face of the first protruding sub - part 12221 facing away from the conductive part 121. The second insulating part 42 can block the burrs at the end face of the first protruding sub - part 12221 facing away from the conductive part 121, reducing the risk of short - circuit inside the battery cell 100 and being beneficial to improving the usage reliability of the battery cell 100. In addition, the second insulating part 42 can completely cover the first welding mark sub - part 5111, reducing the risk of short - circuit caused by burrs, metal debris and other components on the first welding mark sub - part 5111, which is beneficial to improving the usage reliability of the battery cell 100.

[0361] In some embodiments, along the direction from the conductive part 121 to the extending part 122, the second insulating part 42 protrudes from the edge of the second welding mark sub - part 5112 facing away from the first protruding sub - part 12221.

[0362] Along the thickness direction of the current collector 10, the projection of the edge of the second welding mark sub - part 5112 facing away from the first protruding sub - part 12221 falls within the projection of the second insulating part 42, so that the second insulating part 42 can completely cover the second welding mark sub - part 5112 and the first welding mark sub - part 5111.

[0363] During the production process of the electrode, the second insulating part 42 can completely cover the second welding mark sub - part 5112 and the first welding mark sub - part 5111, reducing the risk of short - circuit caused by burrs, metal debris and other components on the second welding mark sub - part 5112 and the first welding mark sub - part 5111, which is beneficial to improving the usage reliability of the battery cell 100.

[0364] In some embodiments, the number of the metal layers 12 is two, and the two metal layers 12 are arranged on the opposite sides of the insulating substrate 11 along the thickness direction of the current collector 10. The number of the active material layers 20 is two, and the two active material layers 20 respectively cover the two metal layers 12. The number of the conductive members 30 is two, and the first connection parts 31 of the two conductive members 30 are respectively welded to the surfaces of the two metal layers 12 facing away from the insulating substrate 11 to form two first welding marks 51. The number of the insulating parts 40 is two, and the second insulating parts 42 of the two insulating parts 40 respectively cover at least part of the two first welding marks 51.

[0365] The number of the metal layers 12, the number of the insulating members 40, the number of the active material layers 20, and the number of the conductive members 30 are all two. The two metal layers 12 respectively cover the opposite sides of the insulating substrate 11 in the thickness direction. The two active material layers 20 respectively cover the conductive portions 121 of the two metal layers 12. The first connecting portion 31 of one conductive member 30 is welded to the surface of one metal layer 12 facing away from the insulating substrate 11 to form a first welding mark 51, and the first connecting portion 31 of the other conductive member 30 is welded to the other metal layer 12 to also form a first welding mark 51. The second insulating portions 42 of the two insulating members 40 are located on the opposite sides of the insulating substrate 11 in the thickness direction and respectively cover the two first welding marks 51.

[0366] By adopting the technical solution of this embodiment, the first electrode plate 1 is provided with two metal layers 12 and two active material layers 20, which is beneficial to improving the energy density of the battery cell 100.

[0367] In some embodiments, along the direction from the conductive portion 121 to the extension portion 122, the second insulating portion 42 protrudes from the end portion of the transition portion 1221 facing the protruding portion 1222.

[0368] The direction from the conductive portion 121 to the extension portion 122 can refer to the direction indicated by the arrow Z in the figure.

[0369] Along the thickness direction of the current collector 10, the projection of the end face of the transition portion 1221 leading out the protruding portion 1222 coincides with the projection of the second insulating portion 42, so that the second insulating portion 42 can cover the end face of the transition portion 1221 leading out the protruding portion 1222.

[0370] During the process of cutting the conductive member 30, burrs are likely to be formed at the end face of the transition portion 1221 facing the protruding portion 1222. In particular, during the process of cutting the conductive member 30 at the first welding mark 51, larger burrs are likely to be formed at the end face of the transition portion 1221 facing the protruding portion 1222. However, the second insulating portion 42 of the embodiment of the present application can block the burrs at the end face of the transition portion 1221 facing the protruding portion 1222 from piercing through the separator 3 and contacting the second electrode plate 2, thereby reducing the short - circuit risk of the battery cell 100 and being beneficial to improving the use reliability of the battery cell 100.

[0371] In some embodiments, the second insulating portion 42 includes a first portion 421 and a second portion 422 connected to each other. The first portion 421 covers at least a part of the first welding mark 51. Along the direction from the conductive portion 121 to the extension portion 122, the second portion 422 protrudes from the extension portion 122, and the second portion 422 is located at the side portion of the second connecting portion 32 along the second direction, where the second direction is perpendicular to the first direction and the thickness direction of the current collector 10.

[0372] In some examples, the insulating member 40 has a constant width structure. The insulating member 40 covers the conductive member 30 and the metal layer 12 along the length direction of the first pole piece 1. In the thickness direction of the current collector 10, the part of the second insulating portion 42 within the projection range of the metal layer 12 and the conductive member 30 is the first part 421, and the part of the second insulating portion 42 outside the projection range of the metal layer 12 and the conductive member 30 is the second part 422.

[0373] In some examples, during the process of cutting the conductive member 30, burrs are likely to be formed at the end face of the transition portion 1221 facing the protruding portion 1222. In particular, during the process of cutting the conductive member 30 at the first welding mark 51, relatively large burrs are likely to be formed at the end face of the transition portion 1221 facing the protruding portion 1222. The second part 422 of the embodiment of the present application can prevent the burrs at the end face of the transition portion 1221 facing the protruding portion 1222 from piercing through the separator 3 and contacting the second pole piece 2, thereby reducing the short-circuit risk of the battery cell 100 and being beneficial to improving the usage reliability of the battery cell 100.

[0374] In some examples, the end face of the transition portion 1221 facing the protruding portion 1222 is prone to being impacted to generate metal debris, and the metal debris is likely to fall into the electrode assembly 101, resulting in a short circuit of the battery cell 100.

[0375] By adopting the technical solution of this embodiment, along the direction from the conductive portion 121 to the extending portion 122, components such as metal debris at the end face of the extending portion 122 away from the active material layer 20 can be located between the second parts 422 of the two insulating members 40, which can reduce the risk of metal debris falling into the electrode assembly 101 and is beneficial to reducing the short-circuit risk.

[0376] In some embodiments, the second parts 422 of the two insulating members 40 are adhered to each other.

[0377] In some examples, the second parts 422 of the two insulating members 40 are located in the hollow area where the transition portion 1221 does not extend beyond the protruding portion 1222, so that the second parts 422 of the two insulating members 40 can approach each other and then be adhered together.

[0378] The second parts 422 of the two insulating members 40 can be pasted together or statically adsorbed together. Of course, other adhesion methods are also possible.

[0379] By adopting the technical solution of this embodiment, after the second parts 422 of the two insulating members 40 are adhered to each other, components such as metal debris at the end face of the extending portion 122 away from the active material layer 20 can be wrapped, making it difficult for the metal debris and other components to fall into the electrode assembly 101, and better reducing the short-circuit risk of the battery cell 100.

[0380] In some embodiments, along the direction of the conductive portion 121 towards the extending portion 122, the second connecting portions 32 of the two conductive members 30 are welded to form a second welding mark 52.

[0381] In some examples, along the direction of the conductive portion 121 pointing to the extending portion 122, the portion of the conductive member 30 protruding from the extending portion 122 forms the second connecting portion 32, such that the second connecting portions 32 of the two conductive members 30 can be directly opposed and close to each other for welding together, and the mark left by the welding is the second welding mark 52. The second connecting portions 32 of the two conductive members 30 can be welded by means such as ultrasonic welding and laser welding.

[0382] By adopting the technical solution of this embodiment, the second connecting portions 32 of the two conductive members 30 can connect the metal layers 12 on the opposite sides of the insulating matrix 11, thereby breaking the insulation limitation of the insulating matrix 11, effectively improving the conductivity of the first electrode tab 1, improving the fast charging performance of the battery cell 100, reducing the heat generation of the battery cell 100, and improving the use reliability of the battery cell 100.

[0383] In some embodiments, the second insulating portion 42 covers the second welding mark 52, and along the direction of the conductive portion 121 pointing to the extending portion 122, the second insulating portion 42 protrudes from the edge of the second welding mark 52 facing away from the conductive portion 121.

[0384] Along the thickness direction of the current collector 10, the projection of the second welding mark 52 falls within the projection of the second insulating portion 42, such that the second insulating portion 42 can completely cover the second welding mark 52.

[0385] By adopting the technical solution of this embodiment, the second insulating portion 42 can completely cover the second welding mark 52, and can prevent components such as tip protrusions and metal debris on the second welding mark 52 from piercing through the separator 3 to connect with the second electrode tab 2, reducing the risk of short circuit and improving the use reliability of the battery cell 100.

[0386] In some embodiments, the electrode assembly 101 includes a second electrode tab 2 having a polarity opposite to that of the first electrode tab 1. The second electrode tab 2 includes a main functional portion 210 and a tab portion 220. The tab portion 220 protrudes from the main functional portion 210 along a first direction; along the direction of the conductive portion 121 towards the extending portion 122, the main functional portion 210 protrudes from the end face of the insulating member 40 facing the active material layer 20, and the main functional portion 210 does not protrude from the end face of the insulating member 40 away from the active material layer 20.

[0387] The second electrode tab 2 may refer to an electrode tab with a polarity opposite to that of the first electrode tab 1. Among them, the first electrode tab 1 is a positive electrode tab and the second electrode tab 2 is a negative electrode tab, or the first electrode tab 1 is a negative electrode tab and the second electrode tab 2 is a positive electrode tab. The first electrode tab 1 and the second electrode tab 2 can be wound after being stacked to form a wound electrode assembly 101; a plurality of first electrode tabs 1 and a plurality of second electrode tabs 2 are stacked to form a laminated electrode assembly 101.

[0388] The second electrode tab 2 includes a main functional part 210 and an electrode ear part 220. The main functional part 210 may refer to the main body part of the second electrode tab 2, and the electrode ear part 220 may refer to the part of the second electrode tab 2 that protrudes from the main functional part 210; when the second electrode tab 2 is a negative electrode tab, the electrode ear part 220 may refer to the protruding structure located at the edge of the negative current collector mentioned above, and the main functional part 210 may include the part of the negative current collector other than the protruding structure and the negative active material layer. When the second electrode tab 2 is a positive electrode tab, the electrode ear part 220 may refer to the protruding structure located at the edge of the positive current collector mentioned above, and the main functional part 210 may include the part of the positive current collector other than the protruding structure and the positive active material layer.

[0389] During the manufacturing process of the second electrode tab 2, the edge of the second electrode tab 2 is die-cut to obtain the electrode ear part 220 and the main functional part 210. During the die-cutting process, burrs are likely to be generated on the end face of the main functional part 210 facing the electrode ear part 220.

[0390] Exemplarily, along the thickness direction of the current collector 10, the projection of the end face of the main functional part 210 close to the electrode ear part 220 falls within the projection of the first insulating part 41 or the projection of the second insulating part 42.

[0391] By adopting the technical solution of this embodiment, the insulating part 40 can prevent the burrs at the end face of the main functional part 210 of the second electrode tab 2 close to the electrode ear part 220 from piercing through the separator 3 and connecting with the first electrode tab 1, reducing the short-circuit risk between the first electrode tab 1 and the second electrode tab 2, which is beneficial to improving the use reliability of the battery cell 100.

[0392] In some embodiments, the electrode assembly 101 includes a second electrode tab 2 with a polarity opposite to that of the first electrode tab 1. The second electrode tab 2 includes a main functional part 210 and an electrode ear part 220. The electrode ear part 220 protrudes from the main functional part 210 along the first direction; along the direction from the conductive part 121 to the extending part 122, the main functional part 210 protrudes from the end face of the extending part 122 facing away from the conductive part 121.

[0393] In some examples, in the thickness direction of the current collector 10, the projection of the end face of the main functional part 210 facing the tab part 220 does not coincide with the projection of the metal layer 12, and the burrs at the end face of the main functional part 210 of the second electrode sheet 2 facing the tab part 220 correspond to the hollowed-out area where the metal layer 12 does not extend beyond the second connection part 32.

[0394] In some examples, in the thickness direction of the current collector 10, the projection of the first welding mark 51 may fall within the projection of the main functional part 210, and the first welding mark 51 may be covered with a second insulating part 42, so that the second insulating part 42 can prevent burrs, metal debris and other components on the first welding mark 51 from piercing the separator 3 and connecting with the second electrode sheet 2, reducing the risk of short circuit and improving the reliability of use of the battery cell 100.

[0395] By adopting the technical solution of this embodiment, the burrs at the end face of the main functional part 210 of the second electrode sheet 2 facing the tab part 220 correspond to the hollowed-out area where the metal layer 12 does not extend beyond the second connection part 32, which can also reduce the short-circuit risk of the battery cell 100 and improve the reliability of use of the battery cell 100.

[0396] In some embodiments, the current collector 10 further includes a conductive protective layer 13, and at least a part of the conductive protective layer 13 is located between the active material layer 20 and the conductive part 121.

[0397] The conductive protective layer 13 may refer to a conductive structure provided between the active material layer 20 and the conductive part 121, and this conductive structure can conduct electricity, enabling the battery cell 100 to output or input electric energy. The conductive protective layer 13 can be a structure with equal thickness or a structure with unequal thickness.

[0398] Exemplarily, a part of the conductive protective layer 13 is located between the active material layer 20 and the conductive part 121, and another part covers the transition part 1221 and protrudes outside the active material layer 20.

[0399] Exemplarily, the entire conductive protective layer 13 is located between the active material layer 20 and the conductive part 121.

[0400] In some examples, the conductive protective layer 13 may contain conductive carbon black and a binder. On the one hand, it plays a buffering and lubricating role between the active material and the metal layer, and can relieve the damage of the particles in the active material layer 20 to the metal layer 12 during the rolling process of the first electrode sheet 1; on the other hand, the conductive carbon black can reduce the contact resistance between the particles and the metal layer 12, which is beneficial to improving the use performance of the battery cell 100.

[0401] During the rolling process of the first electrode tab 1, the thickness of the metal layer 12 is relatively thin, and the particles in the active material layer 20 can cause damage to the metal layer 12, resulting in problems such as cracks in the metal layer 12. The conductive protective layer 13 in the embodiment of the present application can separate the active material layer 20 and the metal layer 12 while protecting the metal layer 12, reducing the risks such as cracks in the metal layer 12 caused by rolling the active material layer 20, which is beneficial to improving the current-carrying capacity of the metal layer 12.

[0402] In some embodiments, along the direction from the conductive portion 121 to the extension portion 122, the conductive protective layer 13 protrudes from the end face of the active material layer 20 facing the protruding portion 1222.

[0403] The conductive protective layer 13 protrudes from the active material layer 20. The conductive protective layer 13 can completely separate the metal layer 12 and the active material layer 20. In addition, it can provide an epitaxial space during the rolling process of the active material layer 20, which is beneficial to the subsequent conductive protective layer 13 being able to completely separate the metal layer 12 and the active material layer 20.

[0404] By adopting the technical solution of this embodiment, the conductive protective layer 13 can completely separate the active material layer 20 and the metal layer 12. The conductive protective layer 13 has better protection ability for the metal layer 12, and the first electrode tab 1 has better current-carrying capacity, which is beneficial to improving the fast charging performance and use reliability of the battery cell 100.

[0405] In some embodiments, along the direction from the conductive portion 121 to the extension portion 122, the protruding distance range of the conductive protective layer 13 from the end face of the active material layer 20 facing the protruding portion 1222 is 0.3 mm to 0.8 mm.

[0406] The protruding distance of the conductive protective layer 13 from the end face of the active material layer 20 facing the protruding portion 1222 is S3, where 0.3 mm ≤ S3 ≤ 0.8 mm. The value of S3 can be 0.3 mm, 0.8 mm, and any value between 0.3 mm and 0.8 mm. For example, the value of S3 can be, but is not limited to, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm.

[0407] The design of S3 ≥ 0.3 mm can enable the conductive protective layer 13 to completely separate the active material layer 20 and the metal layer 12. The conductive protective layer 13 has better protection ability for the metal layer 12, and the first electrode tab 1 has better current-carrying capacity, which is beneficial to improving the fast charging performance and use reliability of the battery cell 100. The design of S3 ≤ 0.8 mm makes the conductive protective layer 13 not too large and occupy space, which is beneficial to saving the internal space of the battery cell 100 and improving the energy density of the battery cell 100.

[0408] By adopting the technical solution of this embodiment, the overcurrent capacity and energy density of the battery cell 100 can be better balanced.

[0409] In some embodiments, along the first direction, the conductive protective layer 13 and the first welding mark 51 are arranged at intervals.

[0410] In some examples, the conductive protective layer 13 is arranged at intervals from the first connecting portion 31, and the first insulating portion 41 covers the part of the conductive protective layer 13 located between the first connecting portion 31 and the active material layer 20.

[0411] By adopting the technical solution of this embodiment, the first connecting portion 31 will not be welded to the conductive protective layer 13, which can reduce risks such as false soldering and is beneficial to improving the welding reliability between the first connecting portion 31 and the metal layer 12.

[0412] In some embodiments, the second insulating portion 42 is connected to the first electrode tab 1.

[0413] The second insulating portion 42 can be connected to the metal layer 12, can also be connected to the conductive member 30, or can be connected to the active material layer 20. Among them, the second insulating portion 42 can be connected to the first electrode tab 1 by means of bonding or pasting.

[0414] By adopting the technical solution of this embodiment, the second insulating portion 42 is connected to the first electrode tab 1, and the second insulating portion 42 can be fixed, so as to stably block the burrs at the end of the transition portion 1221 facing the protruding portion 1222, which is beneficial to improving the use reliability of the battery cell 100.

[0415] Please refer to Figure 22 and Figure 23 As shown, in some embodiments, the second insulating portion 42 includes an insulating base layer 423 and an adhesive layer 424, and the adhesive layer 424 is bonded between the insulating base layer 423 and the first electrode tab 1.

[0416] The second insulating portion 42 adopts the structural form of a tape; the insulating base layer 423 can refer to the main body part of the second insulating portion 42, and the adhesive layer 424 can refer to the adhesive covering the surface of the insulating base layer 423. The material of the insulating base layer 423 includes at least one of polyethylene terephthalate (PET replacement), polypropylene, polyethylene and their block copolymers. The material of the adhesive layer 424 includes at least one of polyacrylate, styrene-butadiene rubber, polyisobutylene or butyl rubber.

[0417] By adopting the technical solution of this embodiment, for the structural form of the tape, the tape is easy to fully cover, which helps to reduce the risk of missed coverage and the risk of internal short circuit of the battery cell 100; the insulating base layer 423 can improve the structural strength of the second insulating part 42, reduce the deformation during the fitting process of the second insulating part 42, and is conducive to improving the insulation effect; the adhesive layer 424 can stably fix the insulating base layer 423 on the first pole piece 1 and reduce the risk of the insulating tape falling off.

[0418] In some embodiments, the layer thickness range of the insulating base layer 423 is 6 μm to 15 μm.

[0419] The layer thickness of the insulating base layer 423 is T1, and 6 μm ≤ T1 ≤ 15 μm. It can be understood that the value of T1 can be 6 μm, 15 μm, and any value between 6 μm and 15 μm. Exemplarily, the value of T1 can be, but is not limited to, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm.

[0420] The design of T1 ≥ 6 μm enables the insulating base layer 423 to have a certain thickness to block burrs and achieve insulation; the design of T1 ≤ 15 μm enables the thickness of the insulating base layer 423 not to be too large, which is conducive to reducing the volume occupied by the second insulating part 42 and improving the energy density of the battery cell 100.

[0421] By adopting the technical solution of this embodiment, the internal insulation and energy density of the battery cell 100 can be taken into account simultaneously.

[0422] In some embodiments, the layer thickness range of the adhesive layer 424 is 0.5 μm to 3 μm.

[0423] The layer thickness of the adhesive layer 424 is T2, and 0.5 μm ≤ T2 ≤ 3 μm. It can be understood that the value of T2 can be 0.3 μm, 3 μm, and any value between 0.3 μm and 3 μm. Exemplarily, the value of T2 can be, but is not limited to, 0.3 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm.

[0424] The design of T2 ≥ 0.5 μm enables the adhesive layer 424 to have a certain thickness, so that the second insulating part 42 can be stably bonded to the first pole piece 1, and the insulation reliability of the second insulating part 42 is good; the design of T2 ≤ 3 μm enables the thickness of the adhesive layer 424 not to be too large, which is conducive to reducing the volume occupied by the second insulating part 42 and improving the energy density of the battery cell 100.

[0425] By adopting the technical solution of this embodiment, the insulation reliability and energy density of the battery cell 100 can be taken into account simultaneously.

[0426] In some embodiments, the layer thickness of the insulating base layer 423 ranges from 6 μm to 15 μm; the layer thickness of the adhesive layer 424 ranges from 0.5 μm to 3 μm.

[0427] By adopting the technical solution of this embodiment, the insulation reliability and energy density of the battery cell 100 can be taken into account simultaneously.

[0428] In some embodiments, along the first direction, the size of the insulating member 40 is W, where 3 mm ≤ W ≤ 9 mm.

[0429] In some examples, the insulating member 40 includes a second insulating portion 42, and W is equal to the size of the second insulating portion 42 along the first direction.

[0430] In some examples, the insulating member 40 includes a second insulating portion 42 and a first insulating portion 41, and W is equal to the overall size of the second insulating portion 42 and the insulating coating along the first direction.

[0431] 3 mm ≤ W ≤ 9 mm. It can be understood that the value of W can be 3 mm, 9 mm, and any value between 3 mm and 9 mm. Exemplarily, the value of W can be, but is not limited to, 3 mm, 4 mm, 4.5 mm, 5 mm, 6 mm, 6.5 mm, 7 mm, 8 mm, 9 mm.

[0432] The design of W ≥ 3 mm enables the insulating member 40 to have a certain size along the first direction, which is beneficial to the internal insulation of the battery cell 100; the design of W ≤ 9 mm enables the size of the insulating member 40 along the first direction not to be too large, which is beneficial to reducing the volume occupied by the insulating member 40 and improving the energy density of the battery cell 100.

[0433] By adopting the technical solution of this embodiment, the insulation reliability and energy density of the battery cell 100 can be taken into account simultaneously.

[0434] In some embodiments, 4.5 mm ≤ W ≤ 6.5 mm.

[0435] By adopting the technical solution of this embodiment, along the first direction, the size of the insulating member 40 is relatively reasonable, and the insulation reliability and energy density of the battery cell 100 can be better taken into account.

[0436] In some embodiments, at least part of the thickness of the conductive portion 121 is less than the thickness of the extending portion 122.

[0437] Exemplarily, the extending portion 122 is an equal-thickness structure or generally an equal-thickness structure, and the conductive portion 121 is also an equal-thickness structure or generally an equal-thickness structure, and the thickness t1 of the extending portion 122 is greater than the thickness of the conductive portion 121.

[0438] Exemplarily, the conductive part 121 may have unequal thicknesses. Along the direction in which the conductive part 121 points to the extension part 122, the thickness of the conductive part 121 increases. Specifically, it may increase step by step or increase slowly. The thickness of the part of the conductive part 121 far from the transition part 1221 is less than the thickness of the transition part 1221.

[0439] By adopting the technical solution of this embodiment, the thickness t1 of the extension part 122 is relatively large, and the current-carrying capacity of the extension part 122 is good, which is beneficial to improving the current-carrying capacity of the first electrode sheet 1, reducing the heat generation of the battery cell 100, and is beneficial to improving the fast charging performance and service reliability of the battery cell 100.

[0440] In some embodiments, the conductive part 121 includes a first sub-part 1211 and a second sub-part 1212. The first sub-part 1211 is connected between the second sub-part 1212 and the extension part 122. The first sub-part 1211 and the second sub-part 1212 are covered with an active material layer 20. The thickness of the first sub-part 1211 is greater than the thickness of the second sub-part 1212. The thickness of the extension part 122 is greater than or equal to the thickness of the first sub-part 1211.

[0441] The conductive part 121 may have an unequal-thickness structure. Along the direction in which the conductive part 121 points to the extension part 122, the conductive part 121 is divided into two parts. The part close to the extension part 122 is the first sub-part 1211, and the part far from the extension part 122 is the second sub-part 1212. Both the first sub-part 1211 and the second sub-part 1212 are covered with an active material layer 20.

[0442] In some examples, the first sub-part 1211 may have an equal-thickness structure, and the second sub-part 1212 may have an equal-thickness structure; the thickness t2 of the first sub-part 1211 is greater than the thickness t3 of the second sub-part 1212, and the thickness t1 of the transition part 1221 is greater than or equal to the thickness t2 of the first sub-part 1211, so that the first sub-part 1211 and the second sub-part 1212 form a stepped structure; the thickness t1 of the transition part 1221 may be equal to the thickness t2 of the first sub-part 1211, so that the transition part 1221 and the first sub-part 1211 form an equal-thickness structure; or, the thickness t1 of the transition part 1221 may be greater than the thickness t3 of the second sub-part 1212, so that the first sub-part 1211 and the transition part 1221 form a stepped structure.

[0443] In some examples, the first sub - part 1211 may also be a multi - segment structure. Along the direction from the conductive part 121 to the extension part 122, the thickness of each segment increases in sequence. Exemplarily, the first sub - part 1211 includes a first segment and a second segment. The first segment is located between the second segment and the second sub - part 1212. Along the direction from the conductive part 121 to the extension part 122, the thickness of the first segment gradually increases. The second segment is generally a constant - thickness structure, and the thickness of the second segment is equal to the thickness t1 of the transition part 1221. The thickness of the first segment gradually increases from the thickness t3 of the second sub - part 1212 to the thickness of the second segment. With such a setting, the first segment can be smoothly transition - connected to the second segment and the second sub - part 1212, which is beneficial to reducing stress concentration and improving the structural strength. The thickness of the first segment may be equal to the thickness t1 of the transition part 1221, or the thickness t1 of the transition part 1221 may be greater than the thickness of the first segment.

[0444] During the use of the battery cell 100, along the direction from the conductive part 121 to the extension part 122, the electrons and ions generated by the active material layer 20 are gradually collected on the transition part 1221 through the conductive part 121. The number of electrons and ions flowing through the part of the conductive part 121 close to the transition part 1221 is more than that flowing through the part of the conductive part 121 far from the transition part 1221. Therefore, it is required that the current - carrying capacity of the part of the conductive part 121 close to the transition part 1221 is greater than that of the part of the conductive part 121 far from the transition part 1221.

[0445] In the embodiment of the present application, the first sub - part 1211 is connected between the second sub - part 1212 and the transition part 1221, and the thickness t2 of the first sub - part 1211 is greater than the thickness t3 of the second sub - part 1212, so that the current - carrying capacity of the first sub - part 1211 close to the transition part 1221 is greater than that of the second sub - part 1212 far from the transition part 1221. This can reduce the limitation of the current, improve the current - carrying capacity of the first electrode sheet 1, reduce the heat generation of the battery cell, and is beneficial to improving the use reliability of the battery cell 100.

[0446] In some embodiments, the current collector 10 further includes a conductive protective layer 13. The conductive protective layer 13 includes a first protective part 131 and a second protective part 132. The first protective part 131 is located between the first sub - part 1211 and the active material layer 20, and the second protective part 132 is located between the second sub - part 1212 and the active material layer 20. Among them, the thickness of the first protective part 131 is less than the thickness of the second protective part 132.

[0447] In some examples, along the first direction, the portion of the conductive protective layer 13 located between the first sub - portion 1211 and the active material layer 20 may be the first protective portion 131, and the portion of the conductive protective layer 13 located between the second sub - portion 1212 and the active material layer 20 may be the second protective portion 132. Among them, the thickness t4 of the first protective portion 131 is less than the thickness t5 of the second protective portion 132, and the thickness t2 of the first sub - portion 1211 is greater than the thickness t3 of the second sub - portion 1212, which can reduce the thickness difference of the current collector 10 at the first protective portion 131 and the second protective portion 132.

[0448] Exemplarily, the first sub - portion 1211 is divided into a third part and a fourth part. The third part is located between the above - mentioned first section and the active material layer 20, and the fourth part is located between the above - mentioned second section and the active material layer 20. The third part is located between the fourth part and the second protective portion 132. Along the direction from the conductive portion 121 to the extending portion 122, the thickness of the third part gradually decreases, and the fourth part is generally of an equal - thickness structure, so that the thickness t4 of the first protective portion 131 can be adapted to the thickness t2 of the first sub - portion 1211, making the surface of the conductive protective layer 13 facing away from the insulating substrate 11 close to a plane.

[0449] By adopting the technical solution of this embodiment, the surface of the conductive protective layer 13 facing away from the insulating substrate 11 is close to a plane, which is beneficial to reducing rolling damage and improving the current - carrying capacity of the metal layer 12; in addition, the problem of winding bulging of the current collector 10 can also be reduced.

[0450] In some embodiments, the conductive protective layer 13 further includes a third protective portion 133, and the third protective portion 133 covers the surface of the extending portion 122 facing away from the insulating substrate 11, and the thickness of the third protective portion 133 is less than or equal to the thickness of the first protective portion 131.

[0451] In some examples, along the first direction, the conductive protective layer 13 can be divided into three parts. A part close to the conductive member 30 is the third protective portion 133, a part far from the conductive member 30 is the second protective portion 132, and the part in the middle is the first protective portion 131. Among them, the thickness t4 of the first protective portion 131 is less than the thickness t5 of the second protective portion 132, and the thickness t2 of the first sub - portion 1211 is greater than the thickness t5 of the second protective portion 132, which can reduce the thickness difference of the current collector 10 at the first protective portion 131 and the second protective portion 132; similarly, the thickness t6 of the third protective portion 133 is less than or equal to the thickness t4 of the first protective portion 131, and the thickness t1 of the transition portion 1221 is greater than or equal to the thickness t2 of the first sub - portion 1211, which can reduce the thickness difference of the current collector 10 at the first protective portion 131 and the third protective portion 133, and is beneficial to the surface of the conductive protective layer 13 facing away from the metal layer 12 being close to a plane.

[0452] Exemplarily, the second protection part 132, the third protection part 133, the transition part 1221, and the second sub-part 1212 are all of equal thickness structure, while the first sub-part 1211 and the first protection part 131 are both of unequal thickness structure; the thickness t2 of the first sub-part 1211 and the thickness t4 of the first protection part 131 are adapted to make the surface of the conductive protection layer 13 facing away from the insulating substrate 11 close to a plane.

[0453] By adopting the technical aspects of this embodiment, the setting of the third protection part 133 can make the conductive protection layer 13 protrude from the active material layer 20, so that the active material layer 20 and the metal layer 12 can be better separated. In addition, the thickness of the third protection part 133 is not too large, which is beneficial to reducing material waste and saving the manufacturing cost of the battery cell 100.

[0454] In some embodiments, the thickness t7 of the protruding part 1222 is greater than or equal to the thickness t1 of the transition part 1221.

[0455] Exemplarily, the thickness t7 of the protruding part 1222 can be equal to the thickness t1 of the transition part 1221, so that the protruding part 1222 and the transition part 1221 form an equal thickness structure.

[0456] Exemplarily, the thickness t7 of the protruding part 1222 can also be greater than the thickness t1 of the transition part 1221, so that the protruding part 1222 and the transition part 1221 form a stepped structure.

[0457] By adopting the technical solution of this embodiment, the thickness t7 of the protruding part 1222 is relatively thick, which can improve the current-carrying capacity of the protruding part 1222, is beneficial to improving the current-carrying capacity of the first pole piece 1, reducing the heat generation of the battery cell 100, and is beneficial to improving the fast charging performance and use reliability of the battery cell 100.

[0458] In some embodiments, the thickness of the second active material part 22 is t8, where 0.002 ≤ (t1 - t3) / t8 ≤ 0.08.

[0459] t1 - t3 may refer to the thickness difference between the transition part 1221 and the second sub-part 1212 to characterize the thickening degree of the transition part 1221.

[0460] (t1 - t3) / t8 can be 0.002, 0.08, and any value between 0.002 and 0.08; exemplarily, the value of (t1 - t3) / t8 can be but not limited to 0.002, 0.003, 0.004, 0.008, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08.

[0461] By adopting the technical solution of this embodiment, the setting of 0.002 ≤ (t1 - t3) / t8 ≤ 0.08 enables the thickness difference between the transition part 1221 and the second sub - part 1212 to be within the thickness error range of the active material layer 20. In this way, thickening the transition part 1221 is not likely to cause the surface of the active material layer 20 to bulge, which can reduce subsequent rolling damage and the extrusion damage between the first electrode sheet 1 and other electrode sheets, and is beneficial to improving the service reliability of the battery cell 100.

[0462] In some embodiments, 0.003 ≤ (t1 - t3) / t8 ≤ 0.06.

[0463] By adopting the technical solution of this embodiment, the setting of 0.003 ≤ (t1 - t3) / t8 ≤ 0.06 enables the thickness difference between the transition part 1221 and the second sub - part 1212 to be better within the thickness difference range of the active material layer 20. In this way, thickening the transition part 1221 is even less likely to cause the surface of the active material layer 20 to bulge, which can reduce subsequent rolling damage and the extrusion damage between the first electrode sheet 1 and other electrode sheets, and is beneficial to improving the service reliability of the battery cell 100.

[0464] In some embodiments, 60μm ≤ t8 ≤ 250μm.

[0465] It can be understood that the value of t8 can be 60μm, 250μm, and any value between 60μm and 250μm; for example, the value of t8 can be, but is not limited to, 60μm, 70μm, 80μm, 90μm, 100μm, 120μm, 140μm, 160μm, 180μm, 200μm, 220μm, 250μm.

[0466] The design of t8 ≥ 60μm enables the battery cell 100 to have a higher capacity; the design of t3 ≤ 250μm makes the distance for electrons to escape from the part of the active material layer 20 close to the metal layer 12 not too long, and it is easy for electrons to escape from the part of the active material layer 20 close to the metal layer 12, which is beneficial to improving the capacity of the battery cell 100.

[0467] By adopting the technical solution of this embodiment, the thickness of the second active material part 22 is within a suitable range, and the volume of the active material layer 20 is reasonably set, which is beneficial to improving the fast - charging performance and service reliability of the battery cell 100, and can also reduce the risk of difficult ion escape in the area of the active material layer 20 close to the conductive layer, improving the performance of the battery cell 100.

[0468] In some embodiments, 80μm ≤ t8 ≤ 180μm.

[0469] By adopting the technical solution of this embodiment, with the setting of 80μm ≤ t8 ≤ 180μm, the thickness of the second active material part 22 is within a more appropriate range, and the volume of the active material layer 20 is reasonably set, which is beneficial to improving the fast charging performance and use reliability of the battery cell 100, and can also reduce the risk of difficult ion extraction in the area of the active material layer 20 close to the conductive layer, thereby improving the performance of the battery cell 100.

[0470] In some embodiments, 0.2μm ≤ t1 - t3 ≤ 4.5μm.

[0471] For 0.2μm ≤ t1 - t3 ≤ 4.5μm, it can be understood that the value of t1 - t3 can be 0.2μm, 4.5μm, and any value between 0.2μm and 4.5μm; for example, the value of t1 - t3 can be, but is not limited to, 0.2μm, 0.3μm, 0.1μm, 0.5μm, 1μm, 1.5μm, 1.75μm, 2μm, 3μm, 4μm, 4.5μm.

[0472] By adopting the technical solution of this embodiment, with the design of 0.2μm ≤ t1 - t3 ≤ 4.5μm, the thickening degree of the transition part 1221 is reasonable. On the basis of improving the current-carrying capacity, it can also prevent the thickness of the transition part 1221 from being too large, occupying too much space and weight, which is beneficial to improving the energy density of the battery cell 100.

[0473] In some embodiments, 0.3μm ≤ t1 - t3 ≤ 1.75μm.

[0474] By adopting the technical solution of this embodiment, with the design of 0.3μm ≤ t1 - t3 ≤ 1.75μm, the thickening degree of the transition part 1221 is more reasonable, the current-carrying capacity is better, and it is more beneficial to improving the energy density of the battery cell 100.

[0475] In some embodiments, 1 < t1 / t3 ≤ 4. Optionally, 1.5 < t1 / t3 ≤ 2.5.

[0476] t1 / t3 can refer to the ratio of the thickness t1 of the transition part 1221 to the thickness t3 of the second sub-part 1212, and can also characterize the thickening degree of the transition part 1221.

[0477] For 1 < t1 / t3 ≤ 4, it can be understood that the value of t1 / t3 can be 4 and any value between 1 and 4; for example, the value of t1 / t3 can be, but is not limited to, 1.1, 1.5, 2, 2.5, 3, 3.5, 4.

[0478] By adopting the technical solution of this embodiment, with the design of 1 < t1 / t3 ≤ 4, the thickening degree of the transition part 1221 is reasonable. On the basis of improving the current-carrying capacity, in addition, the thickness of the transition part 1221 is not too large to occupy a large space and weight, which is beneficial to improving the energy density of the battery cell 100.

[0479] In some embodiments, 1.5 < t1 / t3 ≤ 2.5.

[0480] By adopting the technical solution of this embodiment, with the design of 1.5 < t1 / t3 ≤ 2.5, the thickening degree of the transition part 1221 is more reasonable, the current-carrying capacity is better, and it is also more beneficial to improving the energy density of the battery cell 100.

[0481] In some embodiments, 1μm ≤ t1 ≤ 5μm.

[0482] For 1μm ≤ t1 ≤ 5μm, it can be understood that the value of t1 can be 1μm, 5μm, or any value between 1μm and 5μm; for example, the value of t1 can be, but is not limited to, 1μm, 1.1μm, 1.2μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 5μm.

[0483] By adopting the technical solution of this embodiment, with the design of 1μm ≤ t1 ≤ 5μm, the thickness design of the transition part 1221 is reasonable, which is beneficial to improving the current-carrying capacity. In addition, the thickness of the transition part 1221 is not too large to occupy a large space and weight, which is beneficial to improving the energy density of the battery cell 100.

[0484] In some embodiments, 1.2μm ≤ t1 ≤ 3.5μm.

[0485] By adopting the technical solution of this embodiment, with the design of 1.2μm ≤ t1 ≤ 3.5μm, the thickness design of the transition part 1221 is more reasonable, the current-carrying capacity is better, and it is also more beneficial to improving the energy density of the battery cell 100.

[0486] In some embodiments, 0.03 ≤ t6 / t5 ≤ 0.95.

[0487] t6 / t5 can refer to the ratio of the thickness of the third protection part 133 to the thickness of the second protection part 132, which can characterize the thinning degree of the third protection part 133 relative to the second protection part 132.

[0488] 0.03 ≤ t6 / t5 ≤ 0.95. It can be understood that the value of t6 / t5 can be 0.03, 0.95, or any value between 0.03 and 0.95; by way of example, the value of t6 / t5 can be, but is not limited to, 0.03, 0.1, 0.125, 0.15, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95.

[0489] By adopting the technical solution of this embodiment, with the design of 0.03 ≤ t6 / t5 ≤ 0.95, the thinning degree of the conductive protection layer 13 is reasonable, and it can be better adapted to the thickening degree of the transition part 1221, which is beneficial to the surface of the conductive protection layer 13 facing away from the metal layer 12 approaching a plane, beneficial to reducing roll-pressing damage, and improving the current-carrying capacity of the metal layer 12.

[0490] In some embodiments, 0.125 ≤ t6 / t5 ≤ 0.8.

[0491] By adopting the technical solution of this embodiment, with the design of 0.03 ≤ t6 / t5 ≤ 0.95, the thinning degree of the conductive protection layer 13 is more reasonable, and it can be even better adapted to the thickening degree of the transition part 1221, which is beneficial to the surface of the conductive protection layer 13 facing away from the metal layer 12 approaching a plane, beneficial to reducing roll-pressing damage, and improving the current-carrying capacity of the metal layer 12.

[0492] In some embodiments, 0.5 μm ≤ t6 ≤ 4 μm.

[0493] 0.5 μm ≤ t6 ≤ 4 μm. It can be understood that the value of t6 can be 0.5 μm, 4 μm, or any value between 0.5 μm and 4 μm; by way of example, the value of t6 can be, but is not limited to, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 4 μm, 5 μm.

[0494] By adopting the technical solution of this embodiment, with the setting of 0.5 μm ≤ t6 ≤ 4 μm, the third protection part 133 has a certain thickness, thus reducing the risk of cracking of the metal layer 12; in addition, it will not cause the third protection part 133 to protrude from the second protection part 132 facing away from the metal layer 12 due to the third protection part 133 being too thick, and it can also reduce material accumulation and production costs.

[0495] In some embodiments, 1 μm ≤ t6 ≤ 2 μm.

[0496] By adopting the technical solution of this embodiment, with the setting of 1 μm ≤ t6 ≤ 2 μm, the third protection part 133 has a more reasonable thickness, thus better reducing the risk of cracking of the metal layer 12 and production costs.

[0497] In some embodiments, along the first direction, the size of the first sub - part 1211 is W1, and the size of the second sub - part 1212 is W2, where W1 / (W1 + W2)≤0.45.

[0498] Exemplarily, the size of the first sub - part 1211 being W1 may refer to the width of the first sub - part 1211, and the size of the second sub - part 1212 being W2 may refer to the width of the second sub - part 1212. W1 + W2 may refer to the width of the conductive part 121.

[0499] W1 / (W1 + W2) may refer to the proportion of the first sub - part 1211 occupying the conductive part 121 in the width direction of the first electrode sheet 1.

[0500] For W1 / (W1 + W2)≤0.45, it can be understood that the value of W1 / (W1 + W2) can be 0.45 and any value between 0 and 0.45; exemplarily, the value of W1 / (W1 + W2) can be but is not limited to 0.001, 0.1, 0.2, 0.3, 0.4, 0.45.

[0501] By adopting the technical solution of this embodiment, the design of W1 / (W1 + W2)≤0.45 enables the active material layer 20 to cover the first sub - part 1211, so as to improve the over - current capacity and reduce the heat generation of the battery cell 100; in addition, along the second direction, the first sub - part 1211 does not occupy too much area, which is beneficial to reducing the occupied space and weight of the first sub - part 1211 and is beneficial to improving the energy density of the battery cell 100.

[0502] In some embodiments, along the first direction, the size of the first sub - part 1211 is W2, where 10mm≤W2≤100mm.

[0503] It can be understood that the value of W2 can be 10mm, 100mm and any value between 10mm and 100mm; exemplarily, the value of W2 can be but is not limited to 10mm, 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm.

[0504] By adopting the technical solution of this embodiment, the design of 10mm≤W2≤100mm enables the active material layer 20 to cover the first sub - part 1211, so as to improve the over - current capacity and reduce the heat generation of the battery cell 100; in addition, along the second direction, the first sub - part 1211 does not occupy too much area, which is beneficial to reducing the occupied space and weight of the first sub - part 1211 and is beneficial to improving the energy density of the battery cell 100.

[0505] The battery cell 100 of the present application will be described below in conjunction with some embodiments.

[0506] Embodiment 1

[0507] Referring to Figures 3 - 10 As shown, in this embodiment, the battery cell 100 includes an end cap 201, a housing 202, and an electrode assembly 101. The electrode assembly 101 is installed at the housing 202, and the end cap 201 covers the opening of the housing 202 to seal the housing 202. The end cap 201 is provided with an electrode lead-out portion 2011.

[0508] In this embodiment, the electrode assembly 101 includes a wound first electrode tab 1, a second electrode tab 2, and a separator 3. The separator 3 is located between the first electrode tab 1 and the second electrode tab 2, and the polarities of the first electrode tab 1 and the second electrode tab 2 are opposite. Among them, the first electrode tab 1 can be a positive electrode tab, and the second electrode tab 2 is a negative electrode tab.

[0509] In this embodiment, the first electrode tab 1 includes a current collector 10, an active material layer 20, and a conductive member 30. The current collector 10 includes an insulating substrate 11, a metal layer 12, and a conductive protective layer 13. The opposite two surfaces of the insulating substrate 11 in the thickness direction are covered with the metal layer 12. The surface of the metal layer 12 facing away from the insulating substrate is covered with the conductive protective layer 13, and the surface of the conductive protective layer 13 facing away from the insulating substrate is covered with the active material layer 20.

[0510] In this embodiment, the two metal layers 12 are both welded with the conductive member 30. The conductive member 30 includes a first connection portion 31 and a second connection portion 32 connected to each other. The first connection portion 31 is welded to the metal layer 12 to form a first weld mark 51, and the second connection portions 32 of the two conductive members 30 are welded to form a second weld mark 52.

[0511] In this embodiment, the electrode assembly 101 further includes an insulating member 40. The insulating member 40 includes a first insulating portion 41, and the first insulating portion 41 is located between the first connection portion 31 and the active material layer 20.

[0512] In this embodiment, the metal layer 12 includes a conductive portion 121 and an extension portion 122. The extension portion 122 includes a transition portion 1221 and at least one protruding portion 1222. The transition portion 1221 is connected between the conductive portion 121 and the transition portion 1221. The protruding portion 1222 protrudes from the transition portion 1221 along a first direction perpendicular to the thickness direction of the current collector 10. The active material layer 20 covers the conductive portion 121, and the protruding portion 1222 and the transition portion 1221 are not covered with the active material layer 20.

[0513] In this embodiment, the number of the protruding portions 1222 is multiple, and the multiple protruding portions 1222 are arranged at intervals along a second direction perpendicular to the first direction and the thickness direction of the current collector 10.

[0514] In this embodiment, the protruding portion 1222 includes a first protruding sub-portion 12221 and a second protruding sub-portion 12222. The first protruding sub-portion 12221 is connected between the second protruding sub-portion 12222 and the transition portion. The dimension of the second protruding sub-portion 12222 along the second direction is smaller than the dimension of the first protruding sub-portion 12221 along the second direction. The first protruding sub-portion 12221 is welded to the first connecting portion 31 to form a first weld mark sub-portion 5111, and the second protruding sub-portion 12222 is welded to the first connecting portion 31 to form a second weld mark portion 512. The first weld mark sub-portion 5111 and the second weld mark sub-portion 5112 form a first weld mark 51.

[0515] The spacing range between the first weld mark 51 and the active material layer 20 is 0.3 mm to 5 mm.

[0516] Embodiment Two

[0517] Refer to Figures 11 - 17 As shown, the difference between this embodiment and Embodiment One is that: the first connecting portion 31 is welded to the protruding portion 1222 to form a first weld mark portion 511, the first connecting portion 31 is welded to the transition portion 1221 to form a second weld mark portion 512, and the first weld mark portion 511 and the second weld mark portion 512 form a first weld mark 51.

[0518] The insulating member 40 further includes a second insulating portion 42. One side of the second insulating portion 42 covers the first weld mark 51 and the second weld mark 52, and the other side covers the first insulating portion 41.

[0519] In this embodiment, the protruding portion 1222 is welded to the first connecting portion 31 to form a first weld mark portion 511, and the transition portion 1221 is welded to the first connecting portion 31 to form a second weld mark portion 512; the first weld mark portion 511 and the second weld mark portion 512 form a first weld mark 51.

[0520] Embodiment Three

[0521] Refer to Figures 18 - 21 As shown, the difference between this embodiment and Embodiment Two is that: refer to Figures 14 - 17 As shown, the insulating member 40 includes a second insulating portion 42 and does not include the first insulating portion 41. One side of the second insulating portion 42 covers the first weld mark 51, and the other side of the second insulating portion 42 covers the active material layer 20.

[0522] In some embodiments, refer to Figure 2 As shown, a battery device 1100 is provided, including the battery cell 100 of the above embodiment.

[0523] The battery device 1100 of the embodiment of the present application uses the above battery cell 100. The battery cell 100 has a large energy density, and the battery device 1100 has a large energy density.

[0524] In some embodiments, referring to Figure 1 as shown, an electrical device is provided, including the battery device 1100 as described in the above embodiments.

[0525] For the electrical device of the embodiments of the present application, by adopting the above battery device 1100, the energy density of the battery cell 100 is large, which is beneficial to improving the endurance and performance of the electrical device.

[0526] The descriptions of the above embodiments tend to emphasize the differences between the embodiments. For their similarities, reference can be made to each other. For the sake of brevity, they will not be elaborated herein.

[0527] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be covered by the scope of the claims and the specification of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, Comprising: A housing provided with an electrode lead-out portion; An electrode assembly at least partially accommodated in the housing, the electrode assembly including a first pole piece, the first pole piece including a conductive member, a current collector, and an active material layer, the conductive member being connected to the electrode lead-out portion; the current collector including an insulating substrate and a metal layer, the insulating substrate, the metal layer, and the active material layer being stacked along the thickness direction of the current collector, at least a portion of the metal layer being located between the insulating substrate and the active material layer; The metal layer includes a conductive portion and an extension portion extending outward from an end portion of the conductive portion in a first direction, the first direction being perpendicular to the thickness direction of the current collector; the conductive portion is covered with the active material layer, and the extension portion is not covered with the active material layer; The conductive member is welded to a surface of the extension portion facing away from the insulating substrate to form a first welding mark, and the spacing range between the first welding mark and the active material layer is 0.3 mm to 5 mm.

2. The battery cell according to claim 1, wherein: The spacing range between the first welding mark and the active material layer is 0.5 mm to 2.8 mm.

3. The battery cell according to claim 1, wherein: The conductive member includes a first connection portion and at least one second connection portion, the first connection portion and the second connection portion being arranged along the first direction, the first connection portion and the second connection portion being connected, the second connection portion being connected to the electrode lead-out portion, the first connection portion being welded to a surface of the extension portion facing away from the insulating substrate to form the first welding mark, and the second connection portion being located on a side of the extension portion facing away from the conductive portion.

4. The battery cell according to claim 3, characterized in that: Along the first direction, the first welding mark is spaced apart from an end face of the first connection portion facing the active material layer.

5. The battery cell according to claim 4, wherein: Along the first direction, the spacing range between the first welding mark and the end face of the first connection portion facing the active material layer is 0.3 mm to 1.2 mm.

6. The battery cell according to claim 3, characterized in that: The first welding mark includes a first welding mark portion, the extension portion includes at least one protruding portion, the protruding portion is connected to the conductive portion, and the first connection portion is welded to a surface of the protruding portion facing away from the insulating substrate to form the first welding mark portion; Along a second direction, the size of the protruding portion is smaller than the size of the conductive portion, wherein the second direction is perpendicular to the first direction and the thickness direction of the current collector.

7. The battery cell according to claim 6, wherein: Along the second direction, the first welding mark portion extends from one side edge of the protruding portion to the other side edge of the protruding portion.

8. The battery cell according to claim 6, wherein: The protruding portion includes a first protruding sub-portion and a second protruding sub-portion, and the second protruding sub-portion is connected between the conductive portion and the first protruding sub-portion; Along the second direction, the size of the second protruding sub-portion is smaller than the size of the first protruding sub-portion, and the size of the first protruding sub-portion is smaller than the size of the conductive portion; The first welding mark portion includes a first welding mark sub-portion; the first connection portion is welded to a surface of the first protruding sub-portion facing away from the insulating substrate to form the first welding mark sub-portion.

9. The battery cell according to claim 8, wherein: Along the second direction, the first welding mark sub-portion extends from one side edge of the first protruding sub-portion to the other side edge of the first protruding sub-portion.

10. The battery cell according to claim 8, wherein: The first welding mark portion further includes a second welding mark sub-portion, and the first connecting portion is welded to the surface of the second protruding sub-portion facing away from the insulating substrate to form the second welding mark sub-portion.

11. The battery cell according to claim 10, wherein: Along the second direction, the second welding mark sub-portion extends from one side edge of the second protruding sub-portion to the other side edge of the second protruding sub-portion.

12. The battery cell according to claim 6, wherein: The number of the protruding portions is multiple, and the multiple protruding portions are arranged at intervals along the second direction. Each protruding portion is welded to the first connecting portion, and the second direction is perpendicular to the first direction and the thickness direction of the current collector.

13. The battery cell according to claim 12, characterized in that: The first connecting portion includes multiple first connecting sub-portions, and the multiple first connecting sub-portions are arranged at intervals along the second direction. The number of the second connecting portions is multiple, and each of the first connecting sub-portions is connected to each of the second connecting portions in a one-to-one correspondence; Each of the first connecting sub-portions is welded to the surface of each of the protruding portions facing away from the insulating substrate.

14. The battery cell according to claim 6, characterized in that: The first welding mark includes a second welding mark portion, and the extending portion further includes a transition portion. The transition portion is connected between the protruding portion and the conductive portion. The first connecting portion is welded to the surface of the transition portion facing away from the insulating substrate to form the second welding mark portion; Along the second direction, the size of the transition portion is greater than the sum of the sizes of all the protruding portions.

15. The battery cell according to claim 14, wherein: Along the second direction, the size of the conductive portion is L1, the size of the transition portion is L2, and 0.8 ≤ L2 / L1 ≤ 1.

16. The battery cell according to claim 14, characterized in that: Along the second direction, the size of the transition portion is L2, the size of the second welding mark portion is L3, and 0.8 ≤ L3 / L2 ≤ 1.

17. The battery cell according to claim 14, wherein: The number of the protruding portions is multiple, and the multiple protruding portions are arranged at intervals along the second direction; The first connecting portion includes a second connecting sub-portion and multiple first connecting sub-portions. The multiple first connecting sub-portions are arranged at intervals along the second direction. Each of the first connecting sub-portions is welded to the surface of each of the protruding portions facing away from the insulating substrate; The number of the second connecting portions is multiple. Along the first direction, one side of each of the first connecting sub-portions is connected to each of the second connecting portions in a one-to-one correspondence, and the other side of each of the first connecting sub-portions is connected to the second connecting sub-portion. The second connecting sub-portion is continuously arranged along the second direction; The second connecting sub-portion is welded to the surface of the transition portion facing away from the insulating substrate.

18. The battery cell according to any one of claims 3 to 17, characterized in that: Along the first direction, the first connecting portion and the active material layer are arranged at intervals.

19. The battery cell according to any one of claims 3 to 17, characterized in that: The electrode assembly further includes an insulating member. The insulating member includes a first insulating portion. The first insulating portion covers the surface of the extending portion facing away from the insulating substrate, and the entire first insulating portion is located between the first welding mark and the active material layer.

20. The battery cell according to claim 19, wherein: The first insulating portion is located between the first connecting portion and the active material layer.

21. The battery cell according to claim 20, characterized in that: The insulating member further includes a second insulating portion, and at least a part of the second insulating portion covers the first welding mark.

22. The battery cell according to claim 21, wherein: Along the first direction, one side of the second insulating portion covers the first welding mark, and the other side of the second insulating portion covers at least a part of the area of the first insulating portion.

23. The battery cell according to claim 3, wherein: The electrode assembly further includes an insulating member, and the insulating member includes a second insulating portion, and at least a part of the second insulating portion covers the first welding mark.

24. The battery cell according to claim 23, characterized in that: Along the first direction, one side of the second insulating portion covers the first welding mark, and the other side of the second insulating portion covers at least a part of the active material layer.

25. The battery cell according to any one of claims 21 to 24, characterized in that: The number of the metal layers is two, and the two metal layers are arranged on opposite sides of the insulating substrate along the thickness direction of the current collector. The number of the active material layers is two, and the two active material layers respectively cover the two metal layers. The number of the conductive members is two, and the first connection portions of the two conductive members are respectively welded to the surfaces of the two metal layers facing away from the insulating substrate to form two first welding marks. The number of the insulating members is two, and the second insulating portions of the two insulating members respectively cover at least a part of the two first welding marks.

26. The battery cell according to claim 25, characterized in that: The second insulating portion includes a first part and a second part connected to each other. The first part covers at least a part of the first welding mark. Along the direction of the conductive portion towards the extending portion, the second part protrudes from the extending portion, and the second part is located on the side of the second connection portion along the second direction, where the second direction is perpendicular to the first direction and the thickness direction of the current collector.

27. The battery cell according to claim 26, wherein: The second parts of the two insulating members are in contact with each other.

28. The battery cell according to claim 25, wherein: The second connection portions of the two conductive members are welded to form a second welding mark.

29. The battery cell according to claim 28, wherein: The second insulating portion covers the second welding mark. Along the direction of the conductive portion pointing to the extending portion, the second insulating portion protrudes from the edge of the second welding mark facing away from the conductive portion.

30. The battery cell according to claim 19, characterized in that: The electrode assembly includes a second electrode plate having a polarity opposite to that of the first electrode plate. The second electrode plate includes a main body functional portion and a tab. The tab protrudes from the main body functional portion along the first direction. Along the direction of the conductive portion towards the extending portion, the main body functional portion protrudes from the end face of the insulating member facing the active material layer, and the main body functional portion does not protrude from the end face of the insulating member away from the active material layer.

31. The battery cell according to any one of claims 1 to 17, characterized in that: The electrode assembly includes a second electrode plate having a polarity opposite to that of the first electrode plate. The second electrode plate includes a main body functional portion and a tab. The tab protrudes from the main body functional portion along the first direction. Along the direction of the conductive portion pointing to the extending portion, the main body functional portion protrudes from the end face of the extending portion facing away from the conductive portion.

32. The battery cell according to any one of claims 1 to 17, characterized in that: The current collector further includes a conductive protective layer, and at least a part of the conductive protective layer is located between the active material layer and the conductive portion.

33. The battery cell according to claim 32, wherein: Along the direction of the conductive portion towards the extending portion, the conductive protective layer protrudes from the end face of the active material layer close to the extending portion.

34. The battery cell according to claim 33, characterized in that: Along the direction of the conductive portion towards the extending portion, the protruding distance range of the conductive protective layer from the end face of the active material layer facing the extending portion is 0.3 mm to 0.8 mm.

35. The battery cell according to claim 32, wherein: Along the first direction, the conductive protective layer and the first welding mark are arranged at intervals.

36. The battery cell according to any one of claims 1 to 17, characterized in that: At least a part of the thickness of the conductive portion is smaller than the thickness of the extending portion.

37. The battery cell according to claim 36, wherein: The conductive part includes a first sub-part and a second sub-part. The first sub-part is connected between the second sub-part and the extension part. The first sub-part and the second sub-part are covered with the active material layer. The thickness of the first sub-part is greater than that of the second sub-part, and the thickness of the extension part is greater than or equal to that of the first sub-part.

38. The battery cell according to claim 37, wherein: The current collector further includes a conductive protection layer, which includes a first protection part and a second protection part. The first protection part is located between the first sub-part and the active material layer, and the second protection part is located between the second sub-part and the active material layer; wherein, the thickness of the first protection part is less than that of the second protection part.

39. The battery cell according to claim 38, wherein: The conductive protection layer further includes a third protection part, which covers the surface of the extension part facing away from the insulating substrate. The thickness of the third protection part is less than or equal to that of the first protection part.

40. A battery device, characterized in that: Including the battery cell according to any one of claims 1 to 39.

41. An electrical device, characterized in that: Including the battery device according to claim 40.

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