CN223363343U

CN223363343U - Battery monomer, positive plate, battery device and electricity utilization device

Info

Publication number: CN223363343U
Application number: CN202422284451.4U
Authority: CN
Inventors: 邓博楷; 王耀辉; 杨俭; 黄思应
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2024-09-19
Filing date: 2024-09-19
Publication date: 2025-09-19
Anticipated expiration: 2034-09-19

Abstract

The application provides a battery monomer, a positive plate, a battery device and an electricity utilization device. The battery unit comprises a shell, an electrode assembly and an isolating layer, wherein the electrode assembly is arranged in the shell and comprises a positive plate, the positive plate comprises a current collector and an active material layer, the current collector comprises a current collecting part, an empty foil part and a tab which are connected with each other, the active material layer is arranged on the current collecting part, the empty foil part is arranged between the current collecting part and the tab, and the isolating layer is covered on at least part of the empty foil part.

Description

Battery monomer, positive plate, battery device and electricity utilization device

Technical Field

The application relates to the field of batteries, in particular to a battery monomer, a positive plate, a battery device and an electricity utilization device.

Background

Batteries are widely used in electronic devices such as cellular phones, notebook computers, battery cars, electric vehicles, electric airplanes, electric ships, electric toy vehicles, electric toy ships, electric toy airplanes, electric tools, and the like.

In the related art, the battery cell is easy to generate internal short circuit due to the breakage of the separator, and the reliability of the battery cell is still to be improved.

Disclosure of utility model

In view of the above, the present application provides a battery cell, a positive electrode sheet, a battery device, and an electric device, which can solve the problem of insufficient reliability of the battery cell due to internal short circuit caused by breakage of a separator.

In a first aspect, an embodiment of the application provides a battery cell, which comprises a shell, and an electrode assembly arranged in the shell, wherein the electrode assembly comprises a positive plate, the positive plate comprises a current collector and an active material layer, the current collector comprises a current collecting part, an empty foil part and a tab which are mutually connected, the active material layer is arranged on the current collecting part, the empty foil part is arranged between the current collecting part and the tab, the electrode assembly further comprises an isolation layer, and the isolation layer covers at least part of the empty foil part.

In the scheme of the embodiment of the application, the battery monomer comprises a shell and an electrode assembly, the electrode assembly is accommodated in the shell, the electrode assembly comprises a positive plate, the positive plate comprises a current collector and an active material layer, the current collector comprises a current collecting part, an empty foil part and a tab which are mutually connected, the active material layer is arranged on the current collecting part, the empty foil part is arranged between the current collecting part and the tab, the electrode assembly further comprises an isolation layer, and the isolation layer is covered on at least part of the empty foil part, so that burrs on the empty foil part can be shielded by the isolation layer, the problem that the adjacent positive plate and the negative plate are in contact with a short circuit due to the fact that the isolation piece is pierced by burrs on the empty foil part is solved, and the reliability of the battery monomer is improved.

In some embodiments, the isolation layer is disposed on at least one side of the thickness direction of the blank foil portion.

In the scheme of the embodiment of the application, the isolating layer is arranged on at least one side of the thickness direction of the empty foil part, so that the isolating layer can shield burrs covered on the thickness direction of the empty foil part, and the risk of short circuit in the battery cell caused by the fact that the isolating piece is pierced by the burrs in the thickness direction of the empty foil part is reduced.

In some embodiments, the hollow foil portion includes end surfaces on both sides in a thickness direction thereof and side surfaces connected to the both end surfaces, and the spacer layer is provided on part of the side surfaces.

In the scheme of the embodiment of the application, the empty foil part comprises the end faces at the two sides of the thickness direction of the empty foil part and the side faces connected with the two end faces, and the isolation layer is arranged on part of the side faces, so that the isolation layer can shield burrs covered on the side faces of the empty foil part, and the risk that the side faces pierce the isolation piece to cause short circuit in the battery cell is reduced.

In some embodiments, the separator includes a first end and a second end that are disposed opposite to each other, the first end is disposed on a surface of the hollow foil portion in a thickness direction, the second end extends out of the hollow foil portion in a direction away from the current collecting portion, the two separators are disposed on two sides of the positive plate, and the second ends of the two separators are connected to each other.

In the scheme of the embodiment of the application, the isolating layers comprise the first ends and the second ends which are oppositely arranged, the first ends are arranged on the surface of the empty foil part in the thickness direction, so that the first ends can shield burrs covered on the empty foil part in the thickness direction, the second ends extend out of the empty foil part, the second ends of the two isolating layers which are respectively arranged on the two sides of the positive plate are connected with each other, the burrs on the side surfaces can be separated from the isolating pieces through the isolating layers, and the arrangement difficulty of the isolating layers is reduced.

In some embodiments, at least a portion of the second end extends to an end of the tab proximate the hollow foil portion.

In the scheme of the embodiment of the application, at least part of the second end extends to one end of the lug close to the empty foil part, and part of the isolation layer extending to the lug can play a role in reinforcing the lug, so that the risk of cracking of the root part of the lug is reduced, the contact area of the isolation layer and the current collector is increased, and the connection strength of the isolation layer and the current collector is improved.

In some embodiments, the minimum dimensions between the active material layer and the tab, which are respectively disposed on two sides of the current collector in the thickness direction, are different, the two separation layers are respectively disposed on two sides of the hollow foil portion, one end of each separation layer is connected to the hollow foil portion, the other end of each separation layer is connected to the active material layer, and the extension dimensions of the separation layers disposed on two sides of the hollow foil portion on the current collector are the same.

In the scheme of the embodiment of the application, the minimum sizes of the active material layers and the lugs which are respectively arranged at the two sides of the current collector in the thickness direction are different, the two isolation layers are respectively arranged at the two sides of the empty foil part, one end of each isolation layer is connected with the empty foil part, the other end of each isolation layer is connected with the active material layer, the extension sizes of the isolation layers respectively arranged at the two sides of the empty foil part at the current collecting part are the same, and the lengths of the active material layers at the two sides can be balanced through the isolation layers, so that the problem of lithium precipitation of the positive electrode sheet caused by the staggering of the active material layers at the two sides is solved.

In some embodiments, both separator layers extend to a side of the active material layer facing away from the current collector.

In the scheme of the embodiment of the application, the two isolation layers extend to one side of the active material layer, which is away from the current collector, so that the connection reliability of the isolation layers and the active material layer can be improved, and the setting difficulty of the isolation layers is reduced.

In some embodiments, the separator to current collector maximum dimension is less than the active material layer to current collector maximum dimension along the thickness direction of the positive electrode sheet.

In the scheme of the embodiment of the application, the maximum size from the isolating layer to the current collector is smaller than the maximum size from the active material layer to the current collector along the thickness direction of the positive plate, so that the problem of swelling of the electrode assembly caused by overhigh isolating layer arrangement is solved.

In some embodiments, the separator layer is disposed at an end of the hollow foil portion facing away from the current collector portion and extends toward the current collector portion.

In the scheme of the embodiment of the application, burrs are more easily generated at one end of the empty foil part, which is away from the current collecting part, after the foil is die-cut, so that the isolating layer is arranged at one end of the empty foil part, which is away from the current collecting part, and extends towards the current collecting part, and the production cost of the battery monomer can be saved under the condition that the isolating layer effectively covers the burrs.

In some embodiments, the separator layer is an insulating material to enable the separator layer and the current collector to be insulated from each other.

In the scheme of the embodiment of the application, the isolation layer is made of an insulating material, and the isolation layer and the current collector are mutually insulated, so that when the isolation piece is damaged, the isolation layer can still mutually insulate the adjacent positive and negative plates, and the reliability of the battery cell is improved.

In a second aspect, an embodiment of the present application provides a positive electrode sheet, which is applied to the battery cell of the first aspect, where the positive electrode sheet includes a current collector and an active material layer, the current collector includes a current collecting portion, an empty foil portion and a tab that are connected to each other, the active material layer is disposed on the current collecting portion, the empty foil portion is disposed between the current collecting portion and the tab, and the electrode assembly further includes an isolation layer, where the isolation layer covers at least a portion of the empty foil portion.

In the scheme of the embodiment of the application, the positive plate comprises a current collector and an active material layer, the current collector comprises a current collecting part, an empty foil part and a tab which are connected with each other, the active material layer is arranged on the current collecting part, the empty foil part is arranged between the current collecting part and the tab, the electrode assembly further comprises an isolation layer, and the isolation layer is covered on at least part of the empty foil part, so that the isolation layer can shield burrs on the empty foil part, the problem that the burrs on the empty foil part puncture the isolation piece to cause contact short circuit of adjacent positive and negative plates is solved, and the reliability of the battery cell is improved.

In a third aspect, an embodiment of the present application provides a battery device, including the battery cell of the embodiment of the first aspect.

In a fourth aspect, an embodiment of the present application provides an electrical device, including the battery device of the embodiment of the third aspect.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to designate like parts throughout the figures. In the drawings:

FIG. 1 is a schematic view of a vehicle according to an embodiment of the present application;

Fig. 2 is a schematic structural view of a battery device according to an embodiment of the present application;

fig. 3 is a schematic view illustrating a structure of a battery module according to an embodiment of the present disclosure;

fig. 4 is an exploded view of a battery cell according to an embodiment of the present application;

fig. 5 is a schematic view showing a partial structure of an electrode assembly of a battery cell according to an embodiment of the present application;

fig. 6 is a schematic structural diagram of a positive electrode sheet of a battery cell according to an embodiment of the present application;

FIG. 7 is a cross-sectional view at A-A in FIG. 6;

FIG. 8 is a cross-sectional view at B-B in FIG. 6;

Fig. 9 is a schematic structural view of a positive electrode sheet of a battery cell according to another embodiment of the present application;

FIG. 10 is a cross-sectional view at C-C in FIG. 9 in an embodiment of the application;

fig. 11 is a cross-sectional view at C-C in fig. 9 in another embodiment of the application.

Reference numerals illustrate:

1. 101, motor, 102, controller;

2. Battery device, 201, battery module, 202, box, 2021, first box, 2022, second box, 3, battery cell, 4, shell, 5, electrode assembly, 6, top cover assembly;

7. Positive plate, 71, current collector, 72, active material layer, 711, current collector, 712, empty foil, 713, tab, 7121, end face, 7122, side face, 721, base section, 722, thinned section;

51. isolation layer 511, first end 512, second end;

8. And 9, a negative plate and a separator.

Detailed Description

Embodiments of the technical scheme of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical aspects of the present application, and thus are merely examples, and are not intended to limit the scope of the present application.

It should be noted that unless otherwise indicated, technical or scientific terms used in the embodiments of the present application should be given the ordinary meanings as understood by those skilled in the art to which the embodiments of the present application belong.

In the description of the embodiments of the present application, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the embodiments of the present application and simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the embodiments of the present application.

Furthermore, the technical terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In the description of the embodiments of the present application, the meaning of "plurality" is two or more unless explicitly defined otherwise.

In describing embodiments of the present application, unless explicitly stated or limited otherwise, the terms "mounted," "connected," "secured" and the like should be construed broadly, and may, for example, be fixedly connected, detachably connected, or integrally formed, mechanically connected, electrically connected, directly connected, indirectly connected through an intervening medium, or in communication between two elements or in an interaction relationship between two elements. The specific meaning of the above terms in the embodiments of the present application will be understood by those of ordinary skill in the art according to specific circumstances.

In the description of embodiments of the application, unless expressly specified and limited otherwise, a first feature "up" or "down" on a second feature may be that the first and second features are in direct contact, or that the first and second features are in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

Currently, the application of power batteries is more widespread from the development of market situation. The power battery is not only applied to energy storage power supply systems such as hydraulic power, firepower, wind power and solar power stations, but also widely applied to electric vehicles such as electric bicycles, electric motorcycles, electric automobiles, and the like, and a plurality of fields such as military equipment, aerospace, and the like. With the continuous expansion of the application field of the power battery, the market demand of the power battery is also continuously expanding.

In the present application, the battery cells may include a lithium ion secondary battery cell, a lithium ion primary battery cell, a lithium sulfur battery cell, a sodium lithium ion battery cell, a sodium ion battery cell, or a magnesium ion battery cell, which is not limited in the embodiment of the present application. The battery cell may be in a cylindrical shape, a flat shape, a rectangular parallelepiped shape, or other shapes, which is not limited in this embodiment of the application.

Reference to a battery in accordance with an embodiment of the present application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in the present application may include a battery module or a battery pack, or the like. The battery generally includes a case for enclosing one or more battery cells. The case body can prevent liquid or other foreign matters from affecting the charge or discharge of the battery cells.

The battery cell is easily internally short-circuited due to breakage of the separator.

In the pole piece processing process, burrs are easy to generate on the surface of the current collector after die cutting, and in the pole piece winding, pressing and even using processes, the burrs are easy to pierce the separator to cause the contact short circuit of the positive pole piece and the negative pole piece.

Based on the above-mentioned problem, the battery monomer includes casing and electrode assembly, electrode assembly holds in the casing, the electrode assembly includes the pole piece, the pole piece includes current collector and active material layer, the current collector includes interconnect's collector portion, empty foil portion and utmost point ear, active material layer sets up in collector portion, empty foil portion sets up between collector portion and utmost point ear, electrode assembly still includes the isolation layer, through covering the isolation layer in at least partial empty foil portion, so that the isolation layer can shelter from the burr that is located empty foil portion, with the problem that the adjacent pole piece contact short circuit is led to improvement empty foil portion burr puncture the separator, the single reliability of battery has been promoted.

The technical scheme described by the embodiment of the application is suitable for a battery device and an electric device using the battery device.

The battery cell comprises an electrode assembly and electrolyte which are arranged in the shell, wherein the electrode plate comprises a positive electrode plate and a negative electrode plate, and the electrode assembly further comprises a separator. The battery cell mainly relies on metal ions to move between the positive and negative electrode plates to operate.

Specifically, the positive plate comprises a positive current collector and a positive active material layer, wherein the positive active material layer is coated on the surface of the positive current collector, the positive current collector comprises a positive current collecting part and a positive lug connected with the positive current collecting part, the positive current collecting part is coated with the positive active material layer, and the positive lug is not coated with the positive active material layer. Taking a lithium ion battery as an example, the positive current collector may be aluminum or a composite material containing an aluminum plating layer, the positive active material layer includes a positive active material, and the positive active material may be lithium cobaltate, lithium iron phosphate, ternary lithium, lithium manganate or the like. The negative electrode sheet comprises a negative current collector and a negative electrode active material layer, wherein the negative electrode active material layer is coated on the surface of the negative current collector, the negative current collector comprises a negative current collecting part and a negative electrode lug connected with the negative current collecting part, the negative current collecting part is coated with the negative electrode active material layer, and the negative electrode lug is not coated with the negative electrode active material layer. The negative current collector may be copper or a composite material containing a copper plating layer, and the negative electrode active material layer includes a negative electrode active material, which may be carbon or silicon, or the like. The material of the separator may be PP (polypropylene) or PE (polyethylene), etc.

The electric device may be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, an electric tool, or the like. The vehicle may be a fuel oil vehicle, a gas vehicle or a new energy vehicle, the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended range vehicle, etc., the spacecraft includes an airplane, a rocket, a space plane, a spacecraft, etc., the electric toy includes a fixed or movable electric toy such as a game machine, an electric vehicle toy, an electric ship toy, an electric plane toy, etc., and the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembling electric tool, and a railway electric tool such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact electric drill, a concrete vibrator, an electric planer, etc. The embodiment of the application does not limit the electric device in particular.

In the embodiment of the application, the battery cell can be a secondary battery, and the secondary battery refers to a battery cell which can activate the active material in a charging mode to continue to use after the battery cell discharges.

The battery cell may be a lithium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel hydrogen battery, a nickel cadmium battery, a lead storage battery, etc., which is not limited by the embodiment of the application. The battery cell may be in a cylindrical shape, a flat shape, a rectangular parallelepiped shape, or other shapes, which is not limited in this embodiment of the application.

The battery device according to the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery device mentioned in the present application may include a battery module, a battery pack, or the like. The battery pack generally includes a case for enclosing one or more battery cells. The case body can prevent liquid or other foreign matters from affecting the charge or discharge of the battery cells.

It should be understood that the technical solutions described in the embodiments of the present application are not limited to the above-described battery devices and electric devices, but may be applied to all battery devices including a case and electric devices using the battery devices, but for simplicity of description, the following embodiments are all described by taking an electric vehicle as an example.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a vehicle 1 according to some embodiments of the application. The vehicle 1 can be a fuel oil vehicle, a fuel gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle or a range-extending vehicle. The interior of the vehicle 1 is provided with a battery device 2, and the battery device 2 may be provided at the bottom or at the head or at the tail of the vehicle 1. The battery device 2 may be used for power supply of the vehicle 1, for example, the battery device 2 may serve as an operating power source of the vehicle 1. The vehicle 1 may also include a controller 102 and a motor 101, the controller 102 being configured to control a battery to power the motor 101, for example, for operating power requirements during start-up, navigation, and travel of the vehicle 1.

In some embodiments of the application, the battery device 2 may not only serve as an operating power source for the vehicle 1, but also as a driving power source for the vehicle 1, instead of or in part instead of fuel oil or natural gas, to provide driving power for the vehicle 1.

Fig. 2 is a schematic view showing the structure of a battery device according to an embodiment of the present application.

The battery device 2 according to embodiments of the present application may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly may include a plurality of battery cells 3, and the plurality of battery cells 3 are connected in series, parallel, or series-parallel by a bus bar member.

In some embodiments, the battery cell assembly is generally formed by an arrangement of a plurality of battery cells 3.

As an example, the battery cell assembly may be a battery module 201, and the battery module 201 is formed by arranging and fixing a plurality of battery cells 3 into one independent module. As an example, the battery module 201 may be formed by binding a plurality of battery cells 3 by a tie.

In some embodiments, the battery device may be a battery pack including a housing 202 and one or more battery cell assemblies housed in the housing 202.

As an example, the battery cell assembly may be the battery module 201, and the battery cell assembly may be accommodated in the case in such a manner that the battery module 201 is fixed in the case.

As an example, the battery cell assembly may be accommodated in the case 202 by directly fixing the plurality of battery cells 3 to the case 202.

As an example, the tank 202 may include a first tank 2021 and a second tank 2022. The first housing 2021 and the second housing 2022 are fastened together, so that a closed space is formed inside the housing 202 to accommodate the battery cell assembly. The closing means covering or closing, and can be sealing or unsealing. The first housing 2021 may be a top cover or a bottom plate.

As an example, the tank 202 may include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are respectively connected with the frame, so that a closed space is formed inside the case 202 to accommodate the battery cell assembly.

In some embodiments, the tank 202 may be part of the chassis structure of the vehicle. For example, portions of the tank 202 may become at least a portion of the floor of the vehicle, or portions of the tank 202 may become at least a portion of the cross members and stringers of the vehicle.

Fig. 3 shows a schematic structure of a battery module 201 according to an embodiment of the present application.

In some embodiments, as shown in fig. 2 and 3, the battery cells 3 are plural, and the plural battery cells 3 are connected in series, parallel or series-parallel to form the battery module 201. The plurality of battery modules 201 are connected in series, in parallel or in series-parallel to form a whole, and are accommodated in the case 202.

The plurality of battery cells 3 in the battery module 201 may be electrically connected through a bus member to realize parallel connection or serial connection or series-parallel connection of the plurality of battery cells 3 in the battery module 201.

In the present application, the battery cell 3 may include a lithium ion battery cell, a sodium ion battery cell, a magnesium ion battery cell, or the like, which is not limited in the embodiment of the present application.

Fig. 4 is an exploded view of a battery cell according to an embodiment of the present application. The battery cell 3 refers to the smallest unit constituting the battery. As shown in fig. 4, the battery cell 3 includes a top cap assembly 6, a case 4, and an electrode assembly 5.

The electrode assembly 5 is a component in which electrochemical reactions occur in the battery cells 3. One or more electrode assemblies 5 may be contained within the case 4. The electrode assembly 5 is mainly formed by winding or stacking a pole piece, which is divided into a positive pole piece and a negative pole piece, and a separator is generally provided between the positive pole piece and the negative pole piece. The portions of the positive electrode sheet and the negative electrode sheet having active materials constitute an electrode body, and the portions of the positive electrode sheet and the negative electrode sheet having no active materials constitute tabs, respectively. The positive electrode tab and the negative electrode tab may be located at one end of the electrode body together or at two ends of the electrode body respectively. During charge and discharge of the battery cell 3, the positive electrode active material and the negative electrode active material react with the electrolyte, and the tab is connected to the electrode terminal to form a current loop.

The electrode assembly 5 may be a wound structure, a laminated structure, or a hybrid structure of wound and laminated structures.

In some embodiments, the electrode assembly 5 is a coiled structure. The positive plate and the negative plate are wound into a winding structure.

In some embodiments, electrode assembly 5 is a lamination stack. As an example, the positive electrode sheet, the negative electrode sheet may be provided in plurality, a plurality of positive electrode sheets and a plurality of negative electrode sheets may be alternately stacked, the separator may be provided in plurality and provided between any adjacent positive electrode sheets or negative electrode sheets, respectively, or the separator may be provided continuously and provided between any adjacent positive electrode sheets or negative electrode sheets by folding.

In some embodiments, the electrode assembly 5 may have a cylindrical shape, a flat shape, a polygonal column shape, or the like.

In some embodiments, the electrode assembly 5 is provided with tabs that can conduct current away from the electrode assembly. The tab includes a positive tab and a negative tab.

The battery cell 3 may include a housing 4. The case 4 is an assembly for cooperating with the top cap assembly 6 to form an internal environment of the battery cell 3, wherein the formed internal environment may be used to accommodate the electrode assembly 5, an electrolyte (not shown in the drawings), and other components. The shell 4 can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell), an aluminum-plastic film or the like. In some embodiments, the housing 4 may be a sealed structure or a non-sealed structure. As an example, when the case 4 is of a non-sealing structure, the case 4 plays a role of protecting the electrode assembly 5, and a sealing pouch for sealing the electrode assembly and the electrolyte is further included between the case 4 and the electrode assembly 5. In particular, the sealed bag may be a bag-like insulating member or an aluminum plastic film. When the case 4 has a sealed structure, the case is used to encapsulate the electrode assembly 5, the electrolyte, and other components.

As an example, the battery cell 3 may be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or other shaped battery cell, and the prismatic battery cell includes a square-case battery cell, a blade-shaped battery cell, a polygonal-prismatic battery cell, such as a hexagonal-prismatic battery cell, etc., and the present application is not particularly limited.

The case 4 and the top cap assembly 6 may be separate components, and one or more openings may be provided in the case 4, and the one or more top cap assemblies 6 cover the openings to form the internal environment of the battery cell 3. Alternatively, the top cover assembly 6 and the housing 4 may be integrated. Alternatively, the cap assembly 6 and the housing 4 may be formed with a common connection surface prior to the other components being housed, and the cap assembly 6 is then allowed to cover the housing 4 when it is desired to encapsulate the interior of the housing 4.

Referring to fig. 5, 6 and 7, fig. 5 is a schematic view illustrating a portion of an electrode assembly of a battery cell according to an embodiment of the application, fig. 6 is a schematic view illustrating a structure of a positive electrode tab of a battery cell according to an embodiment of the application, and fig. 7 is a sectional view of fig. 6 at A-A.

In a first aspect, as shown in fig. 4 to 7, an embodiment of the present application provides a battery cell 3, where the battery cell 3 includes a case 4 and an electrode assembly 5, the electrode assembly 5 is disposed in the case 4, the electrode assembly 5 includes a positive electrode sheet 7, the positive electrode sheet 7 includes a current collector 71 and an active material layer 72, the current collector 71 includes a current collecting portion 711, an empty foil portion 712 and a tab 713 connected to each other, the active material layer 72 is disposed on the current collecting portion 711, the empty foil portion 712 is disposed between the current collecting portion 711 and the tab 713, and the electrode assembly 5 further includes an isolation layer 51, where the isolation layer 51 covers at least a portion of the empty foil portion 712.

In the scheme of the embodiment of the application, the battery cell 3 comprises a shell 4 and an electrode assembly 5, the electrode assembly 5 is accommodated in the shell 4, the electrode assembly 5 comprises a positive plate 7, the positive plate 7 comprises a current collector 71 and an active material layer 72, the current collector 71 comprises a current collecting part 711, an empty foil part 712 and a tab 713 which are mutually connected, the active material layer 72 is arranged on the current collecting part 711, the empty foil part 712 is arranged between the current collecting part 711 and the tab 713, the electrode assembly 5 further comprises an isolation layer 51, and the isolation layer 51 covers at least part of the empty foil part 712 so that the isolation layer 51 can shield burrs on the empty foil part 712 to solve the problem that the burrs of the empty foil part 712 pierce a separator 9 to cause contact short circuit of adjacent positive and negative plates 8, thereby improving the reliability of the battery cell 3.

The electrode assembly 5 includes positive and negative electrode sheets 7 and 8 stacked or wound together, and a separator 9 insulating between adjacent positive and negative electrode sheets 8.

The current collector 71 includes a current collecting portion 711, an empty foil portion 712, and a tab 713, which are connected to each other, the current collecting portion 711 is configured to carry the active material layer 72, the empty foil portion 712 corresponds to a overhang region of the negative electrode sheet 8, and the tab 713 is configured to output current to the outside. The tab 713 may be obtained by die-cutting the current collector 71, or the tab 713 may be welded to the empty foil portion 712.

The outer surface of the hollow foil portion 712 has burrs, and the isolating layer 51 covers the outer surface of the hollow foil portion 712, so that the isolating layer 51 can be a patch arranged on the hollow foil portion 712, the patch covers the burrs, the burrs can not extend out of the isolating layer 51 and are gentle and sharp, or the isolating layer 51 is colloid, the burrs are completely sealed in the colloid layer, or the burrs are partially sealed in the colloid layer to reduce the length of the burrs, so that the risk that the burrs pierce the isolating piece 9 under the action of external force is reduced.

The isolation layer 51 is covered on the empty foil portion 712, so that the isolation layer 51 and the current collector 71 are independent, the isolation layer 51 can be directly adhered on the empty foil portion 712 to improve stability of the isolation layer 51, or the isolation layer 51 and the empty foil portion 712 are partially connected or arranged at intervals, the isolation layer 51 is located between the isolation piece 9 and the empty foil portion 712, and orthographic projection of the isolation layer 51 on the current collector 71 is located on the empty foil portion 712.

Optionally, the isolation layer 51 covers the entire outer surface of the hollow foil portion 712, so that the isolation layer 51 may shield the entire hollow foil portion 712 from burrs.

The width of the barrier layer 51 may be flexibly designed, alternatively the barrier layer 51 may have a width D between 3mm and 10 mm. Illustratively, the barrier layer 51 has a width D of 3mm, 5mm, 8mm, 10mm, or the like.

Alternatively, the thickness of the spacer layer 51 is between 9 μm and 30 μm, and exemplary spacer layer 51 thicknesses are 9 μm, 20 μm, 30 μm, or the like.

In some embodiments, as shown in fig. 5 to 7, the isolation layer 51 is made of an insulating material, so that the isolation layer 51 and the current collector 71 can be insulated from each other.

In these embodiments, the isolation layer 51 is made of an insulating material, and the isolation layer 51 and the current collector 71 are insulated from each other, so that when the separator 9 is damaged, the isolation layer 51 can still insulate the adjacent positive and negative electrode plates 8 from each other, so as to improve the reliability of the battery cell 3.

Optionally, the isolation layer 51 may be made of polypropylene, polyvinyl alcohol, polyvinyl ketone, polymethacrylate, polyvinylidene fluoride, nano silica gel, polyacrylonitrile, polyacrylic acid, styrene butadiene rubber, etc.

Alternatively, the isolation layer 51 may be an insulating adhesive layer or insulating adhesive paper.

The base material of the insulating adhesive paper is polypropylene with the thickness of 10 mu m, the adhesive layer is polyacrylate with the thickness of 3 mu m, and the total thickness of the insulating adhesive paper is 13 mu m and the width is 8mm.

The preparation process of the positive plate 7 may be, for example, uniformly mixing positive active materials LiFePO ₄ (LFP), binder polyvinylidene fluoride (PVDF) and conductive carbon black (Super P) according to a mass ratio LPF: PVDF: super p=95:3:2, dispersing the mixed slurry by using 1-methyl-2-pyrrolidone (NMP) as a solvent, coating the obtained positive slurry on both sides of an aluminum foil, baking, rolling, die-cutting and cutting, and then rubberizing, and laminating the insulating adhesive paper on the die-cut edge.

Optionally, the isolation layer 51 is kept stable in the electrolyte, and the peel strength is required to be 15-20N/m after soaking for 1000 hours in the electrolyte. The test method comprises the steps of sticking insulating adhesive paper with the thickness of 13 mu m and the width of 8mm on an aluminum foil with the thickness of 13 mu m, soaking the insulating adhesive paper in electrolyte with the temperature of 70 ℃ for 200 hours, 400 hours, 600 hours, 800 hours and 1000 hours respectively, taking out the insulating adhesive paper, testing the peeling strength of the insulating adhesive paper, sticking a sample after soaking on a stainless steel plate by using a high-speed rail tension machine, sticking one side of the insulating adhesive paper outwards and compacting by using a compression roller, fixing the whole sample on the tension machine, clamping one end of the adhesive paper upwards by using the tension machine, pulling the adhesive paper at the speed of 180 DEG and 50mm/min until the adhesive paper is completely peeled from the aluminum foil, and recording displacement and acting force in the process.

Alternatively, the isolation layer 51 may not break down at 200V voltage, with a resistance greater than 999999mΩ.

Alternatively, the separator 51 has good needling strength, which is greater than 300gf. The test was performed by using a 50mm by 50mm insulating tape with a thickness of 13 μm, using a steel needle with a diameter of 1mm, on a puncture tester, and recording the force at which the insulating tape was punctured at a speed of 50 mm/min.

In some embodiments, as shown in fig. 6 and 7, the isolation layer 51 is provided on at least one side in the thickness direction of the hollow foil portion 712.

In these embodiments, the isolation layer 51 is disposed on at least one side of the thickness direction of the hollow foil portion 712, so that the isolation layer 51 can shield burrs covering the thickness direction of the hollow foil portion 712, so as to reduce the risk that the burrs in the thickness direction of the hollow foil portion 712 pierce the separator 9 to cause internal short circuits of the battery cells 3.

Optionally, the isolation layer 51 is disposed on two sides of the thickness direction of the hollow foil portion 712, so as to improve the coverage area of the isolation layer 51 on the hollow foil portion 712, and improve the effect of covering the burrs with the isolation layer 51.

Optionally, the isolation layer 51 covers the whole surface of the hollow foil portion 712 in the thickness direction, so as to improve the coverage area of the isolation layer 51 on the hollow foil portion 712, and improve the effect of the isolation layer 51 covering burrs.

In some embodiments, as shown in fig. 6 and 7, the blank foil portion 712 includes end faces 7121 on both sides in the thickness direction thereof and side faces 7122 connected to both end faces 7121, and the separator 51 is provided on part of the side faces 7122.

In these embodiments, the hollow foil portion 712 includes end surfaces 7121 on both sides in the thickness direction thereof and side surfaces 7122 connected to both end surfaces 7121, and the separator 51 is provided on a part of the side surfaces 7122 so that the separator 51 can shield burrs covering the side surfaces 7122 of the hollow foil portion 712 to reduce the risk that the side surfaces 7122 burrs pierce the separator 9 to cause short circuits in the battery cells 3.

Optionally, the tab 713 is formed by die cutting a foil, the tab 713 extends out of a part of the side face 7122 of the hollow foil 712, the positive plate 7 includes a plurality of tabs 713 arranged at intervals, and the isolation layer 51 is arranged on the part of the side face 7122 between adjacent tabs 713.

Optionally, the isolation layer 51 covers the entire exposed side 7122, so as to increase the coverage area of the isolation layer 51 on the empty foil portion 712, and increase the burr covering effect of the isolation layer 51.

Optionally, the isolation layer 51 covers the side face 7122 and the two end faces 7121, so as to improve the coverage area of the isolation layer 51 on the empty foil portion 712, and improve the effect of covering burrs by the isolation layer 51.

Optionally, the isolation layer 51 disposed on the end face 7121 and the side face 7122 is integrally formed to reduce the connection difficulty between the isolation layer 51 on the side face 7122 and the side face 7122, or the isolation layers 51 disposed on the end face 7121 and the side face 7122 are respectively connected to the current collector 71, so as to facilitate adjusting the sizes of the isolation layers 51 on the side face 7122 and the end face 7121.

Referring to fig. 8, fig. 8 is a cross-sectional view at B-B in fig. 6.

In some embodiments, as shown in fig. 5 to 8, the separator 51 includes a first end 511 and a second end 512 disposed opposite to each other, the first end 511 is disposed on a surface of the hollow foil portion 712 in a thickness direction, the second end 512 extends out of the hollow foil portion 712 along a direction away from the current collecting portion 711, the two separators 51 are disposed on two sides of the positive electrode sheet 7, and the second ends 512 of the two separators 51 are connected to each other.

In these embodiments, the isolation layer 51 includes a first end 511 and a second end 512 that are disposed opposite to each other, where the first end 511 is disposed on a surface of the hollow foil portion 712 in a thickness direction, so that the first end 511 can shield burrs covered on the hollow foil portion 712 in the thickness direction, and the second end 512 extends out of the hollow foil portion 712, and the second ends 512 of the two isolation layers 51 disposed on two sides of the positive plate 7 are connected to each other, so that the burrs on the side face 7122 and the isolation member 9 can be separated by the isolation layer 51, and the difficulty in setting the isolation layer 51 is reduced.

The surface area of the hollow foil portion 712 in the thickness direction is relatively larger than the surface area of the side face 7122, and thus the separation of the side face 7122 and the spacer 9 by the second end 512 protruding from the hollow foil portion 712 is less difficult than the separate attachment of the spacer 51 to the side face 7122.

The two ends of the hollow foil portion 712 are respectively provided with an isolation layer 51, the first ends 511 of the isolation layer 51 are adhered to the surfaces of the hollow foil portion 712 in the thickness direction, the first ends 511 of the isolation layer 51 are separated from the surfaces of the isolation piece 9 and the hollow foil portion 712 in the thickness direction, so that the risk that burrs on the surfaces of the hollow foil portion 712 in the thickness direction puncture the isolation piece 9, the second ends 512 extend towards the tab 713 and extend out of the hollow foil portion 712, and the two second ends 512 connected with each other are separated from the isolation piece 9 and the side face 7122 of the hollow foil portion 712, so that the risk that burrs on the side face 7122 puncture the isolation piece 9 is reduced.

Specifically, the extension dimension of the second end 512 is smaller than the extension dimension of the tab 713, the plurality of tabs 713 are disposed on the side face 7122 at intervals, and the portions of the second end 512 of the isolation layer 51 located between the adjacent tabs 713 are connected to each other.

In some embodiments, as shown in fig. 6 and 8, at least a portion of the second end 512 extends to an end of the tab 713 adjacent to the hollow foil portion 712.

In these embodiments, at least part of the second end 512 extends to an end of the tab 713 near the hollow foil portion 712, and a part of the isolation layer 51 extending from the tab 713 can serve as a reinforcing tab 713, so as to reduce the risk of cracking at the root of the tab 713, and increase the contact area of the isolation layer 51 and the current collector 71, thereby improving the connection strength of the isolation layer 51 and the current collector 71.

The plurality of tabs 713 are arranged on the side face 7122 at intervals, a part of the second end 512 extending out of the hollow foil portion 712, which is located between the adjacent tabs 713, is adhered to each other, and the other part extends to the root of the tab 713, so that the effect of reinforcing the tab 713 is achieved, and the risk of damage of the tab 713 in the bending process is reduced. The extension dimension of the second end 512 at the tab 713 is flexibly designed.

In some embodiments, as shown in fig. 6 and 8, the separator 51 is disposed at an end of the hollow foil portion 712 facing away from the current collecting portion 711, and extends toward the current collecting portion 711.

In these embodiments, burrs are more easily generated at the end of the hollow foil portion 712 away from the current collecting portion 711 after die cutting of the foil, so that the separator 51 is disposed at the end of the hollow foil portion 712 away from the current collecting portion 711 and extends toward the current collecting portion 711, which can save the production cost of the battery cell 3 under the condition that the separator 51 effectively covers the burrs.

After the foil is die-cut, burrs are more easily generated on the edge of the current collector 71, so that the isolating layer 51 is arranged at one end of the hollow foil part, which is away from the current collector 711, and extends towards the current collector 711, and thus the burrs and the isolating piece 9 can be effectively isolated through the isolating layer 51, the size of the isolating layer 51 is reduced, and the cost of the battery unit 3 is reduced.

Illustratively, the separator 51 overlies the side face 7122 and the separator 51 extends from an end of the end face 7121 proximate to the tab 713 toward the current collector 711.

Referring to fig. 9, 10 and 11, fig. 9 is a schematic structural view of a positive electrode tab of a battery cell according to another embodiment of the application, fig. 10 is a sectional view at C-C in fig. 9 according to an embodiment of the application, and fig. 11 is a sectional view at C-C in fig. 9 according to another embodiment of the application.

In some embodiments, as shown in fig. 5 and 9 to 11, the minimum size between the active material layer 72 and the tab 713, which are respectively disposed on both sides of the current collector 71 in the thickness direction, is different, two separation layers 51 are respectively disposed on both sides of the hollow foil portion 712, one end of each separation layer 51 is connected to the hollow foil portion 712, the other end thereof is connected to the active material layer 72, and the extension sizes of the separation layers 51, which are respectively disposed on both sides of the hollow foil portion 712, at the current collector 711 are the same.

In these embodiments, the minimum dimensions between the active material layers 72 and the tabs 713, which are disposed on both sides in the thickness direction of the current collector 71, are different, the two separator layers 51 are disposed on both sides of the hollow foil portion 712, one end of the separator layer 51 is connected to the hollow foil portion 712, the other end is connected to the active material layers 72, the separator layers 51 disposed on both sides of the hollow foil portion 712 have the same extension dimensions in the current collector portion 711, and the lengths of the active material layers 72 on both sides can be equalized by the separator layers 51, so that the problem of lithium precipitation in the positive electrode sheet 7 due to the staggering of the active material layers 72 on both sides can be improved.

During the coating process, the active material layer 72 may be displaced on both sides in the thickness direction of the current collector 711 due to process capability limitations. This results in that in the adjacent positive and negative electrode sheets 8, part of the active material layer 72 is faced to the current collector 71 of the other electrode sheet, so that lithium ions cannot be intercalated, and thus a problem of lithium precipitation occurs.

The minimum size between the active material layer 72 and the tab 713 is different, that is, the distance between the end of the active material layer 72 near the tab 713 and the tab 713 is different at both sides in the thickness direction. The two active material layers 72 in the thickness direction of the current collector 71 are a first material layer and a second material layer, wherein one end of the first material layer close to the tab 713 is overlapped with one end of the current collector 711 close to the tab 713, and one end of the second material layer close to the tab 713 is located on one side of one end of the current collector 711 close to the tab 713, which is away from the tab 713.

The two isolation layers 51 in the thickness direction of the current collector 71 are a first isolation layer and a second isolation layer, one end of the isolation layer 51 is arranged on the empty foil portion 712, the other end of the isolation layer extends towards the active material layer 72, the first isolation layer extends to one side of the first material layer, which is away from the current collector 71, and the second isolation layer extends to one side of the second material layer, which is away from the current collector 71, so that the connection reliability of the active material layer 72 and the isolation layer 51 is improved, or the second isolation layer and the second material layer are mutually abutted along the arrangement direction of the current collector 711 and the empty foil portion 712, so that the size of the isolation layer 51 is reduced, and the cost of the battery unit 3 is saved.

The isolating layers 51 respectively arranged at the two sides of the empty foil portion 712 have the same extending direction of the current collecting portion 711, so that the staggering generated between the first substance layer and the second substance layer is compensated by the isolating layers 51, so that the parts of the first substance layer and the second substance layer exposed out of the isolating layers 51 are flush at one end facing the tab 713, and the problem of lithium precipitation caused by the opposite alignment of the active substance layers 72 and the current collectors 71 of the adjacent pole pieces is solved.

The extension of the isolation layer 51 in the active material layer 72 may be self-designed, and exemplary extension of the isolation layer 51 in the active material layer 72 may be 0.2mm, 0.5mm, 0.7mm, or the like.

In some embodiments, as shown in fig. 9 and 11, both separator layers 51 extend to a side of active material layer 72 facing away from current collector 71.

In these embodiments, both the isolation layers 51 extend to the side of the active material layer 72 facing away from the current collector 71, which can improve the connection reliability between the isolation layers 51 and the active material layer 72 and reduce the difficulty in setting the isolation layers 51.

Alternatively, one end of the separator 51 covers the entire surface in the thickness direction of the empty foil portion 712, and the other end of the separator 51 extends to a side of the active material layer 72 facing away from the current collector 71.

Optionally, the isolation layer 51 is adhesively connected to a portion of the active material layer 72 to enhance the stability of the isolation layer 51.

In some embodiments, as shown in fig. 9 and 11, the largest dimension of the separator 51 to the current collector 71 is smaller than the largest dimension of the active material layer 72 to the current collector 71 in the thickness direction of the positive electrode sheet 7.

In these embodiments, the maximum size of the separator 51 to the current collector 71 is smaller than the maximum size of the active material layer 72 to the current collector 71 in the thickness direction of the positive electrode sheet 7, to improve the problem of swelling of the electrode assembly 5 due to the separator 51 being disposed too high.

Specifically, the active material layer 72 includes a base section 721 and a thinned section 722 connected to each other, the thinned section 722 is located at an end of the base section 721 facing the tab 713, the thinned section 722 has a smaller size than the base section 721, and the isolation layer 51 extends from a portion of the thinned section 722.

The maximum dimension L1 of the active material layer 72 to the current collector 71 in the thickness direction of the positive electrode sheet 7 refers to the distance between the side surface of the collective segment facing away from the current collector 71 and the current collector 71, and the maximum dimension L2 of the separator 51 to the current collector 71 in the thickness direction of the positive electrode sheet 7 refers to the distance between the side surface of the separator 51 facing away from the thinned segment 722 and the current collector 71 after the separator 51 is covered on the partially thinned segment 722.

In a second aspect, as shown in fig. 4 to 7, an embodiment of the present application provides a positive electrode sheet 7, which is applied to the battery cell 3 of the embodiment of the first aspect, where the positive electrode sheet 7 includes a current collector 71 and an active material layer 72, the current collector 71 includes a current collecting portion 711, an empty foil portion 712 and a tab 713 connected to each other, the active material layer 72 is disposed on the current collecting portion 711, the empty foil portion 712 is disposed between the current collecting portion 711 and the tab 713, and the electrode assembly 5 further includes a separator 51, where the separator 51 covers at least a portion of the empty foil portion 712.

In the scheme of the embodiment of the application, the positive electrode sheet 7 comprises a current collector 71 and an active material layer 72, the current collector 71 comprises a current collecting part 711, a hollow foil part 712 and a tab 713 which are connected with each other, the active material layer 72 is arranged on the current collecting part 711, the hollow foil part 712 is arranged between the current collecting part 711 and the tab 713, the electrode assembly 5 further comprises an isolating layer 51, and the isolating layer 51 covers at least part of the hollow foil part 712 so that the isolating layer 51 can shield burrs on the hollow foil part 712, thereby improving the problem that the burrs on the hollow foil part 712 puncture the isolating piece 9 to cause contact short circuit of adjacent positive and negative electrode sheets 8, and improving the reliability of the battery cell 3.

In some embodiments, as shown in fig. 1 to 11, the battery unit 3 includes a case 4 and an electrode assembly 5, the electrode assembly 5 is disposed in the case 4, the electrode assembly 5 includes a positive electrode sheet 7, the positive electrode sheet 7 includes a current collector 71 and an active material layer 72, the current collector 71 includes a current collector 711, an empty foil 712 and a tab 713 that are connected to each other, the active material layer 72 is disposed on the current collector 711, the empty foil 712 is disposed between the current collector 711 and the tab 713, wherein the electrode assembly 5 further includes an isolation layer 51, the isolation layer 51 is made of an insulating material, the isolation layer 51 includes a first end 511 and a second end 512 that are disposed opposite to each other, the first end 511 is disposed on a surface of the empty foil 712 in a thickness direction, the second end 512 extends from the empty foil 712 in a direction away from the current collector 711, the two isolation layers 51 are disposed on two sides of the positive electrode sheet 7, the second ends 512 of the two isolation layer 51 are connected to each other, the minimum dimensions between the active material layer 72 and the tab 713 that are disposed on two sides of the current collector 71 in a thickness direction are different, the two isolation layers 51 are disposed on two sides of the two isolation layers 712 are disposed on two sides of the empty foil 712, the two isolation layers 51 are disposed on two sides of the largest dimension of the current collector 71 that are disposed on the two sides of the active material layers 72 that are opposite to the largest dimension of the active material layer 72 that is disposed on the two sides of the active material layer 72 that are extending from the active foil 71 to the largest dimension between the active material layer 72 in a direction that is the largest dimension that is opposite to the largest dimension between the active layer 71 and is located to the largest dimension between the active layer and is.

It should be noted that the above embodiments are only used to illustrate the technical solution of the present application, but not to limit the technical solution of the present application, and although the detailed description of the present application is given with reference to the above embodiments, it should be understood by those skilled in the art that the technical solution described in the above embodiments may be modified or some or all technical features may be equivalently replaced, and these modifications or substitutions do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the present application, and all the modifications or substitutions are included in the scope of the claims and the specification of the present application. In particular, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, comprising:

a housing;

An electrode assembly disposed in the case, the electrode assembly including a positive electrode sheet including a current collector including a current collecting portion, an empty foil portion, and a tab connected to each other, and an active material layer disposed in the current collecting portion, the empty foil portion disposed between the current collecting portion and the tab,

Wherein the electrode assembly further comprises an isolation layer covering at least part of the empty foil portion.

2. The battery cell according to claim 1, wherein the separator is provided on at least one side in a thickness direction of the empty foil portion.

3. The battery cell according to any one of claims 1 or 2, wherein the hollow foil portion includes end faces on both sides in a thickness direction thereof and side faces connected to both of the end faces, and the separator is provided on a part of the side faces.

4. The battery cell according to claim 3, wherein the separator includes a first end and a second end disposed opposite to each other, the first end being disposed on a surface of the hollow foil portion in a thickness direction thereof, the second end protruding from the hollow foil portion in a direction away from the current collecting portion,

The two isolating layers are respectively arranged on two sides of the positive plate, and the second ends of the two isolating layers are mutually connected.

5. The battery cell of claim 4, wherein at least a portion of the second end extends to an end of the tab adjacent the hollow foil portion.

6. The battery cell according to any one of claims 1 to 5, wherein the minimum dimensions between the active material layers and the tabs, which are respectively provided on both sides in the thickness direction of the current collector, are different, two separator layers are respectively provided on both sides of the hollow foil portion, one end of each separator layer is connected to the hollow foil portion, the other end thereof is connected to the active material layer, and the separator layers, which are respectively provided on both sides of the hollow foil portion, have the same extension dimensions on the current collector portion.

7. The battery cell of claim 6, wherein both of the separator layers extend to a side of the active material layer facing away from the current collector.

8. The battery cell according to claim 6, wherein a maximum dimension of the separator to the current collector in a thickness direction of the positive electrode sheet is smaller than a maximum dimension of the active material layer to the current collector.

9. The battery cell according to any one of claims 1 to 8, wherein the separator is disposed at an end of the hollow foil portion facing away from the current collecting portion and extends toward the current collecting portion.

10. The battery cell according to any one of claims 1 to 9, wherein the separator is an insulating material so that the separator and the current collector can be insulated from each other.

11. A positive electrode sheet applied to a battery cell according to any one of claims 1 to 10, characterized in that the positive electrode sheet comprises a current collector and an active material layer, the current collector comprises a current collecting part, an empty foil part and a tab which are connected with each other, the active material layer is arranged on the current collecting part, the empty foil part is arranged between the current collecting part and the tab,

12. The positive electrode sheet according to claim 11, wherein the separator is provided on at least one side in a thickness direction of the hollow foil portion.

13. The positive electrode sheet according to any one of claims 11 or 12, wherein the hollow foil portion includes end faces on both sides in a thickness direction thereof and side faces connected to both the end faces, and the separator is provided on part of the side faces.

14. The positive electrode sheet according to claim 11, wherein the minimum dimensions between the active material layers and the tabs, which are respectively provided on both sides in the thickness direction of the current collector, are different, two of the separator layers are respectively provided on both sides of the hollow foil portion, one end of the separator layer is connected to the hollow foil portion, the other end thereof is connected to the active material layer, and the separator layers, which are respectively provided on both sides of the hollow foil portion, have the same extension dimensions on the current collector portion.

15. A battery device comprising a battery cell according to any one of the preceding claims 1-10.

16. An electrical device comprising a battery device according to claim 15.