Battery cell, battery device and electric device

Abstract

The embodiment of the utility model provides a battery monomer, a battery device and a power utilization device, and belongs to the technical field of batteries. The battery cell comprises a shell and an electrode assembly, the electrode assembly comprises a positive pole piece and a negative pole piece; the positive pole piece is provided with a first part extending from the innermost ring to the outer ring, a second part extending from the outermost ring to the inner ring, and a third part positioned between the first part and the second part; in the direction parallel to the winding axis of the winding structure, the height difference between the positive electrode active material layer and the negative electrode active material layer at the first part is H1, and the height difference between the positive electrode active material layer and the negative electrode active material layer at the second part is H2, the height difference between the positive electrode active material layer and the negative electrode active material layer at the third part is H3; h1 is greater than H3, and / or H2 is greater than H3. The lithium separation phenomenon caused by dislocation of the positive pole piece and the negative pole piece in the winding process can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, and more particularly, to a battery monomer, a battery device and a power utilization device. BACKGROUND

[0002] In the related art, a battery monomer includes a negative electrode sheet, a positive electrode sheet and a separator film which are stacked, and the battery monomer needs to satisfy that the area of the negative electrode sheet is larger than the area of the positive electrode sheet. However, in the process of feeding and cutting, the negative electrode sheet or the negative electrode sheet may deviate and be misaligned. The misalignment of the positive electrode sheet and the negative electrode sheet causes that the position of the negative electrode sheet which does not receive lithium ions, and the lithium ions are deposited on the surface of the negative electrode sheet to form lithium dendrites, which pierce the separator film, causing internal short circuit of the battery device, and triggering thermal runaway. Therefore, the battery monomer needs to be improved. SUMMARY

[0003] The present application provides a battery monomer, a battery device and a power utilization device to reduce the lithium deposition phenomenon caused by the misalignment of the positive electrode sheet and the negative electrode sheet in the winding process.

[0004] In a first aspect, an embodiment of the present application provides a battery monomer, comprising

[0005] a housing;

[0006] an electrode assembly accommodated in the housing, the electrode assembly comprising a positive electrode sheet and a negative electrode sheet, the positive electrode sheet and the negative electrode sheet being stacked, the positive electrode sheet and the negative electrode sheet jointly forming a winding structure, the positive electrode sheet comprising a positive electrode main body portion and a positive electrode tab, the positive electrode tab protruding from the positive electrode main body portion, the positive electrode main body portion comprising a positive electrode active material layer, the negative electrode sheet comprising a negative electrode main body portion and a negative electrode tab, the negative electrode tab protruding from the negative electrode main body portion, the negative electrode main body portion comprising a negative electrode active material layer;

[0007] the positive electrode sheet has a first portion extending from an innermost circle to an outermost circle, a second portion extending from the outermost circle to the innermost circle, and a third portion between the first portion and the second portion; in a direction parallel to a winding axis of the winding structure, a height difference between the positive electrode active material layer and the negative electrode active material layer at the first portion is H1, a height difference between the positive electrode active material layer and the negative electrode active material layer at the second portion is H2, and a height difference between the positive electrode active material layer and the negative electrode active material layer at the third portion is H3;

[0008] satisfying H1>H3, and / or, H2>H3.

[0009] In the technical solution, the battery cell with the structure can make the height of the negative active material layer in the first part and / or the second part along the winding axis direction have a larger margin relative to the height of the positive active material layer along the winding axis direction, so that even if the negative active material layer and the positive active material layer are offset due to the smaller tension of the battery cell in the first part or the second part, the risk of misalignment of the negative active material layer and the positive active material layer can be reduced, the adverse effects caused by the offset of the negative active material layer and the positive active material layer can be reduced, the contact stability between adjacent negative active material layers and the overall performance of the battery can be improved.

[0010] In some embodiments, in the case of H1>H3 and H2>H3, in the first part, the negative active material layer includes N segments distributed along the winding direction, and the negative tabs are arranged between adjacent two segments, and along the direction from the third part to the first part, the height of the segment of the negative active material layer closest to the third part along the winding axis direction is less than or equal to the height of the segment of the negative active material layer farthest from the third part along the winding axis direction.

[0011] In some embodiments, in the first part, the height of the segment of the negative active material layer closest to the third part along the winding axis direction is less than the height of the other segment along the winding axis direction.

[0012] In some embodiments, the difference between the height of the segment of the negative active material layer farthest from the third part along the winding axis direction in the first part and the height of the second part along the winding axis direction is less than 5%.

[0013] In some embodiments, in the first part, the difference between the height of each segment of the negative active material layer along the winding axis direction is less than 5%.

[0014] In some embodiments, 0.01mm≤H1-H3≤2mm is satisfied.

[0015] In some embodiments, in the case of H1>H3, in the first part, the negative active material layer includes N segments distributed along the winding direction, and the negative tabs are arranged between adjacent two segments, and along the direction from the third part to the first part, the height of the segment of the negative active material layer closest to the third part along the winding axis direction is less than or equal to the height of the segment of the negative active material layer farthest from the third part along the winding axis direction.

[0016] In some embodiments, in the first portion, a height of one of the two adjacent segments of the negative active material layer near the third portion in the direction of the winding axis is less than a height of the other segment in the direction of the winding axis.

[0017] In some embodiments, in the first portion, a difference between the heights of the segments of the negative active material layer in the direction of the winding axis is less than 5%.

[0018] In some embodiments, 0.01 mm≤H1-H3≤2 mm is satisfied.

[0019] In some embodiments, in the case of H2>H3, in the second portion, the negative active material layer includes N segments distributed in the winding direction, the negative electrode tabs are arranged between adjacent two segments, and a difference between the heights of the segments of the negative active material layer in the direction of the winding axis is less than 5%.

[0020] In some embodiments, the number of turns n of the first portion around the winding axis satisfies 1≤n≤5; and / or, the number of turns z of the second portion around the winding axis satisfies 1≤z≤5.

[0021] In some embodiments, the electrode assembly further includes a separator film, the positive electrode tab, the separator film, and the negative electrode tab are stacked, and the positive electrode tab, the separator film, and the negative electrode tab collectively form a winding structure. In the winding direction, the separator film includes a protection segment that exceeds the winding ending segment of the negative electrode tab, and the number of turns m of the protection segment around the winding axis satisfies m>0.5.

[0022] In a second aspect, the embodiments of the present application provide a battery device, including a plurality of the battery monomer as described in any of the above.

[0023] In a third aspect, the embodiments of the present application provide an energy storage device, including a plurality of the battery monomer as described in any of the above or a plurality of the battery device as described in the above, and the battery monomer or the battery device is used to store or provide electric energy.

[0024] In a fourth aspect, the embodiments of the present application provide an energy storage system, including a power conversion device and the energy storage device as described in the above, and the power conversion device is used to electrically connect a power generation device and the energy storage device.

[0025] In a fifth aspect, the embodiments of the present application provide a power consumption device, including the battery monomer as described in any of the above, the battery device as described in any of the above, the energy storage device as described in the above, or the energy storage system as described in the above, and the battery monomer or the battery device is used to store or provide electric energy.

[0026] In a sixth aspect, the embodiments of the present application provide a charging network, comprising: a charging pile and the energy storage device as described above or the energy storage system as described above, the energy storage device being configured to provide electric energy for the charging pile. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be considered as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0028] Figure 1 A structural schematic diagram of an energy storage system provided by some embodiments of the present application is shown in FIG. 1.

[0029] Figure 2 A structural schematic diagram of a charging network provided by some embodiments of the present application is shown in FIG. 2.

[0030] Figure 3 A structural schematic diagram of a vehicle provided by some embodiments of the present application is shown in FIG. 3.

[0031] Figure 4 A structural exploded view of a battery device provided by some embodiments of the present application is shown in FIG. 4.

[0032] Figure 5 A structural schematic diagram of an electrode assembly provided by some embodiments of the present application is shown in FIG. 5.

[0033] Figure 6 A structural schematic diagram of an electrode assembly provided by some embodiments of the present application is shown in FIG. 6.

[0034] Figure 7 A structural schematic diagram of a negative electrode sheet provided by some embodiments of the present application is shown in FIG. 7.

[0035] Figure 8 A structural schematic diagram of a negative electrode sheet provided by some embodiments of the present application is shown in FIG. 8.

[0036] Figure 9 A structural schematic diagram of a negative electrode sheet provided by some embodiments of the present application is shown in FIG. 9.

[0037] Figure 10 A structural schematic diagram of a negative electrode sheet provided by some embodiments of the present application is shown in FIG. 10.

[0038] Figure 11 A structural schematic diagram of a positive electrode sheet provided by some embodiments of the present application is shown in FIG. 11.

[0039] Figure 12 A structural schematic diagram of an electrode assembly provided by some embodiments of the present application is shown in FIG. 12.

[0040] Reference signs:

[0041] Vehicle 1, battery device 10, electrode assembly 100, negative electrode tab 101, negative electrode active material layer 1011, negative electrode tab 1012, negative electrode main body 1013, positive electrode tab 102, positive electrode active material layer 1021, positive electrode tab 1022, positive electrode main body 1023, separator 103, protection section 1031; first portion 104, second portion 105, third portion 106;

[0042] Box 11, first box body 111, second box body 112, battery cell 12, motor 20, controller 30;

[0043] Energy storage device 2, power conversion device 3, power generation device 4, charging pile 5, connector 6. DETAILED DESCRIPTION

[0044] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0045] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used in the specification of the present application are only for the purpose of describing the specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion. The terms "first", "second" and the like in the specification and claims of the present application and the above description of drawings are used to distinguish different objects, rather than to describe a particular order or primary and secondary relationship.

[0046] In the present application, the phrase "embodiment" means that the specific features, structures or properties described in connection with the embodiment can be included in at least one embodiment of the present application. The appearance of this phrase at various places in the specification does not necessarily mean the same embodiment, nor is it an independent or alternative embodiment to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in the present application can be combined with other embodiments.

[0047] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "attachment" should be understood broadly, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be directly connected, or indirectly connected through an intermediate medium; can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0048] The term "and / or" in the present application is only to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in the present application generally represents that the front and rear associated objects have an "or" relationship.

[0049] The "multiple" appearing in the present application refers to more than two (including two), and similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0050] In the embodiments of the present application, the battery monomer can be a secondary battery, which refers to a battery monomer that can be activated by charging after discharging.

[0051] The battery monomer can be a lithium ion battery, a sodium 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. The embodiments of the present application are not limited thereto.

[0052] The battery monomer can be in the shape of a cylinder, a flat body, a cuboid or other shapes, etc. The embodiments of the present application are not limited thereto. The battery monomer is generally divided into three types according to the packaging method: cylindrical battery monomer, square battery monomer and soft package battery monomer, and the embodiments of the present application are not limited thereto.

[0053] The battery cell includes a shell, an electrode assembly, and an electrolyte. The shell is used to accommodate the electrode assembly and the electrolyte. The electrode assembly is composed of a positive electrode tab, a negative electrode tab, and a separator. The battery cell mainly relies on the movement of metal ions between the positive electrode tab and the negative electrode tab to work. The positive electrode tab includes a positive electrode current collector and a positive electrode active material layer, the positive electrode current collector includes a positive electrode current collector body and a positive electrode tab, the positive electrode active material layer is coated on the surface of the positive electrode current collector body, and the positive electrode tab is not coated with the positive electrode active material layer and protrudes from the positive electrode current collector body. Taking a lithium ion battery as an example, the material of the positive electrode current collector can be aluminum, and the positive electrode active material can be lithium cobaltate, lithium iron phosphate, ternary lithium, or lithium manganate. The negative electrode tab includes a negative electrode current collector and a negative electrode active material layer, the negative electrode current collector includes a negative electrode current collector body and a negative electrode tab, the negative electrode active material layer is coated on the surface of the negative electrode current collector body, and the negative electrode tab is not coated with the negative electrode active material layer and protrudes from the negative electrode current collector body. The material of the negative electrode current collector can be copper, and the negative electrode active material can be carbon or silicon. In order to ensure that the fuse does not occur when passing a large current, the number of positive electrode tabs is multiple and stacked together, and the number of negative electrode tabs is multiple and stacked together.

[0054] The material of the separator can be PP (polypropylene) or PE (polyethylene) or the like. In addition, the electrode assembly can be a winding type structure or a stacking type structure, and the embodiments of the present application are not limited thereto.

[0055] The technical solutions described in the embodiments of the present application are applicable to various electric devices using battery cells, such as mobile phones, portable devices, notebook computers, electric vehicles, electric toys, electric tools, vehicles, ships, and spacecraft, etc. For example, the spacecraft includes an airplane, a rocket, a space shuttle, and a spacecraft, etc. The battery cell is used to store or provide electric energy.

[0056] In recent years, new energy vehicles have made a leap in development. In the field of electric vehicles, power batteries, as the power source of electric vehicles, play an irreplaceable important role. The battery is composed of a box body and a plurality of battery cells accommodated in the box body. Among them, the battery as a core part of new energy vehicles has high requirements in safety and cycle life.

[0057] The inventor found that in the production process of the winding type electrode assembly, the negative electrode tab has no tension when feeding and cutting, and the positive electrode tab and the negative electrode tab may be offset. The offset of the positive electrode tab and the negative electrode tab will cause the negative electrode tab not to accept lithium ions, and lithium ions will be deposited on the surface of the negative electrode tab to form lithium dendrites, which will pierce the separator and cause internal short circuit of the battery, leading to thermal runaway. Therefore, it needs to be improved.

[0058] Based on the above considerations, in order to solve the problem that the negative pole piece has no tension when feeding and cutting, and the positive pole piece and the negative pole piece may be offset, the inventor designs a battery monomer which comprises an outer shell and an electrode assembly, the electrode assembly is accommodated in the outer shell, the electrode assembly comprises a positive pole piece and a negative pole piece, the positive pole piece and the negative pole piece are arranged in a stacked manner, the positive pole piece and the negative pole piece jointly form a winding structure, the positive pole piece comprises a positive pole main body and a positive pole lug, the positive pole lug protrudes from the positive pole main body, the positive pole main body comprises a positive active material layer, the negative pole piece comprises a negative pole main body and a negative pole lug, the negative pole lug protrudes from the negative pole main body, and the negative pole main body comprises a negative active material layer.

[0059] The positive pole piece has a first part extending from the innermost circle to the outermost circle, a second part extending from the outermost circle to the innermost circle, and a third part between the first part and the second part; in the direction parallel to the winding axis of the winding structure, the height difference between the positive active material layer and the negative active material layer at the first part is H1, the height difference between the positive active material layer and the negative active material layer at the second part is H2, and the height difference between the positive active material layer and the negative active material layer at the third part is H3; and H1>H3 and / or H2>H3 are satisfied.

[0060] The battery monomer with the above structure can make the height of the negative active material layer in the first part and / or the second part along the winding axis direction have a larger margin relative to the height of the positive active material layer along the winding axis direction, so that even if the position of the negative active material layer and the positive active material layer is offset due to the smaller tension of the battery monomer at the first part or the second part, the risk of misalignment of the negative active material layer and the positive active material layer can be reduced, the adverse effects caused by the offset of the negative active material layer and the positive active material layer can be reduced, the contact stability between adjacent layers of negative active material layers can be improved, and the overall performance of the battery can be improved.

[0061] The battery apparatus mentioned in the embodiments of the present application can include one or more battery monomer assemblies for providing voltage and capacity. The battery monomer assembly can include a plurality of battery monomers connected in series, in parallel or in a mixed manner through a busbar component.

[0062] In some embodiments, the battery monomer assembly is usually formed by arranging a plurality of battery monomers.

[0063] As an example, the battery cell assembly can be a battery module. The battery module is formed by arranging and fixing a plurality of battery cells into one independent module. As an example, the battery module can be formed by bundling a plurality of battery cells with a cable tie.

[0064] In some embodiments, the battery device can be a battery pack. The battery pack includes a housing and one or more battery cell assemblies. The battery cell assemblies are housed in the housing.

[0065] As an example, the battery cell assembly can be a battery module. The battery cell assembly can be housed in the housing by fixing the battery module in the housing.

[0066] As an example, the battery cell assembly can also be housed in the housing by fixing a plurality of battery cells directly in the housing.

[0067] As an example, the housing can include a first housing and a second housing. The first housing and the second housing are coupled so that an enclosed space is formed inside the housing to receive the battery cell assembly. Here, enclosed means covered or closed, which can be sealed or unsealed. The first housing can be a top cover or a bottom plate.

[0068] As an example, the housing can include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are respectively connected to the frame so that an enclosed space is formed inside the housing to receive the battery cell assembly.

[0069] In some embodiments, the housing can be part of the chassis structure of a vehicle. For example, part of the housing can be at least part of the floor of the vehicle, or part of the housing can be at least part of the cross beam and the longitudinal beam of the vehicle.

[0070] The technical solutions described in the embodiments of the present application are applicable to various electric devices using battery devices, such as mobile phones, portable devices, notebook computers, electric vehicles, electric toys, electric tools, vehicles, ships, and spacecraft, such as aircraft, rockets, space shuttles, and spacecraft. The battery device is used to store or provide electrical energy.

[0071] The embodiments of the present application provide a power storage device including one or more battery clusters to improve the voltage and capacity of the power storage device. The battery cluster can include a plurality of battery devices. The plurality of battery devices are connected in series through a busbar to improve the voltage of the power storage device. When the power storage device includes a plurality of battery clusters, the plurality of battery clusters are connected in parallel to improve the capacity of the power storage device.

[0072] The energy storage device can be used in an energy storage power station, a wind power system, a solar power system, a mobile power system, or a temporary power supply system, etc. The energy storage device can store electric energy as needed and output the electric energy at an appropriate time. For example, the energy storage device can store electric energy during a low electricity consumption period and provide electric energy for relevant users or electric devices during a high electricity consumption period. The energy storage system provided in the embodiments of the present application can be any power system that needs to use an energy storage device.

[0073] In some embodiments, the energy storage device is an energy storage container or an energy storage cabinet.

[0074] In some embodiments, the energy storage device can include a cabinet body and one or more battery clusters, and the battery clusters are accommodated in the cabinet body.

[0075] In some embodiments, the energy storage device can include a thermal management module, a master control module, a general control module, a power distribution module, and a fire-fighting module, etc.

[0076] As an example, the thermal management module can include a liquid cooling unit that provides cooling liquid for adjusting the temperature of the battery monomer to each battery device through a pipeline.

[0077] As an example, the master control module can serve as a battery management unit of the battery cluster for monitoring and managing the battery cluster. The master control module can monitor information such as current, voltage, power, or temperature of the battery cluster. For example, the charging and discharging current and voltage of the battery cluster can be controlled. The master control module includes a slave battery management unit SBMU (SBMU), a fusion switch, and other modules.

[0078] As an example, the general control module can serve as a battery management unit of the energy storage device for monitoring and managing the energy storage device. The general control module can monitor information such as current, voltage, power, state of charge, or temperature of the energy storage device. For example, the charging and discharging current and voltage of the energy storage device can be controlled. As an example, the general control module includes an insulation monitoring module IMM (IMM), a master battery management unit MBMU (MBMU), an Ethernet ETH (ETH), and an optical fiber conversion module, and other modules.

[0079] As an example, the fire-fighting system includes a control panel, a detector, an alarm device, etc., for detecting, alarming, or extinguishing the energy storage system.

[0080] As an example, the power distribution device can be used for power distribution to the power consumption module of the energy storage device.

[0081] The technical solutions described in the embodiments of the present application are applicable to various electric devices using energy storage devices, such as mobile phones, portable devices, notebook computers, electric vehicles, electric toys, electric tools, vehicles, ships and spacecraft, for example, the spacecraft includes airplanes, rockets, space shuttles and spaceships, etc. The energy storage device is used to store or provide electric energy.

[0082] In some embodiments, as shown in Figure 1 The energy storage system can include one or more energy storage devices 2 and a power conversion device 3 (PCS) connected between the power generation device 4 and the energy storage device 2. The power generation device 4 is used to generate electric energy, and the electric energy generated by the power generation device 4 can be stored in the energy storage device 2 through the power conversion device 3. As an example, the power generation device 4 can be a solar panel, a water power generation device, a fire power generation device, a wind power generation device, etc. The specific type of power generation device 4 is not limited in the present application.

[0083] The technical solutions described in the embodiments of the present application are applicable to various electric devices using energy storage systems, such as mobile phones, portable devices, notebook computers, electric vehicles, electric toys, electric tools, vehicles, ships and spacecraft, for example, the spacecraft includes airplanes, rockets, space shuttles and spaceships, etc. The energy storage device is used to store or provide electric energy.

[0084] Please refer to Figure 2 The present application provides a charging network, including a charging pile 5 and an energy storage device 2, the charging pile 5 is electrically connected with the energy storage device 2, and the energy storage device 2 is used to provide electric energy for the charging pile 5. The charging pile 5 and the battery device in the energy storage device 2 are electrically connected through a cable, and the battery device can provide the electric energy stored in itself to the charging pile 5. The charging pile 5 has one or more connectors 6, which are used to connect with electric devices (such as vehicles), so as to supplement the electric energy to the electric devices.

[0085] The energy storage device can be located inside the charging pile (such as a charging and storage integrated machine), or outside the charging pile.

[0086] The present application provides an electric device using a battery monomer or a battery device or an energy storage device or an energy storage system as a power supply. The electric device can be, but is not limited to, a mobile phone, a tablet computer, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship and a spacecraft, etc. The electric toy can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric plane toys, etc. The spacecraft can include airplanes, rockets, space shuttles and spaceships, etc.

[0087] The following embodiments are described by taking a vehicle 1 as an example.

[0088] Please refer to Figure 3 , Figure 3 A structural schematic diagram of the vehicle 1 is provided for some embodiments of the present application. The vehicle 1 can be a fuel automobile, a gas automobile, or a new energy automobile, and the new energy automobile can be a pure electric automobile, a hybrid automobile, or a range extended automobile, etc. The vehicle is internally provided with a battery device 10, which can be arranged at the bottom, head, or tail of the vehicle. The battery device 10 can be used for power supply of the vehicle, for example, the battery device 10 can be used as an operating power source of the vehicle. The vehicle can further include a controller 30 and a motor 20, and the controller 30 is used to control the battery device 10 to supply power to the motor 20, for example, to meet the power demand of the vehicle during starting, navigation, and driving.

[0089] In some embodiments of the present application, the battery device 10 can not only be used as an operating power source of the vehicle, but also be used as a driving power source of the vehicle, to replace or partially replace fuel or natural gas to provide driving power for the vehicle.

[0090] Please refer to Figure 4 , Figure 4 A structural exploded view of the battery device 10 is provided for some embodiments of the present application. The battery device 10 includes a box body 11 and a plurality of battery monomers 12, and the battery monomers 12 are used to be accommodated in the box body 11. Among them, the box body 11 is used to provide an assembly space for the battery monomers 12, and the box body 11 can adopt various structures. In some embodiments, the box body 11 can include a first box body 111 and a second box body 112, and the first box body 111 and the second box body 112 are overlapped with each other, and the first box body 111 and the second box body 112 jointly define an assembly space for accommodating the battery monomers 12. The second box body 112 can be a hollow structure with one end open, and the first box body 111 can be a plate-shaped structure, which is overlapped with the open side of the second box body 112, so that the first box body 111 and the second box body 112 jointly define the assembly space; the first box body 111 and the second box body 112 can also be hollow structures with one side open, and the open side of the first box body 111 is overlapped with the open side of the second box body 112. Of course, the box body 11 formed by the first box body 111 and the second box body 112 can have various shapes, such as a cylinder, a cuboid, etc.

[0091] In the battery device 10, the plurality of battery cells 12 can be connected in series, in parallel, or in a mixed connection, where the mixed connection refers to a connection in which both series and parallel connections are present among the plurality of battery cells 12. The plurality of battery cells 12 can be directly connected in series, in parallel, or in a mixed connection, and the plurality of battery cells 12 can be accommodated in the case 11 as a whole. Alternatively, the plurality of battery cells 12 can be connected in series, in parallel, or in a mixed connection to form a battery module, and a plurality of battery modules can be connected in series, in parallel, or in a mixed connection to form a whole, which can be accommodated in the case 11. The battery device 10 can further include other structures, for example, the battery device 10 can further include a busbar member for electrically connecting the plurality of battery cells 12.

[0092] Please refer to Figure 4 , Figure 4 A partial structure diagram of a battery device 10 according to some embodiments of the present application is provided. The battery device 10 includes a plurality of rows of battery cells 12, and the plurality of rows of battery cells 12 are arranged along a first direction. Each row of battery cells 12 includes a plurality of battery cells 12 arranged along a second direction. The first direction and the second direction are a length direction of the case 11 and a width direction of the case 11, respectively, and the first direction and the second direction are perpendicular to each other.

[0093] According to some embodiments of the present application, referring to Figure 5 , the present application provides a battery cell 12, which includes a housing and an electrode assembly 100.

[0094] The electrode assembly 100 is arranged in the housing, and the electrode assembly 100 includes a negative electrode tab 101, the negative electrode tab 101, and a separator 103, and the positive electrode tab 102, the negative electrode tab 101, and the separator 103 are sequentially stacked.

[0095] The electrode assembly 100 can have a jelly-roll structure, and the electrode assembly 100 is formed by winding the positive electrode tab 102, the negative electrode tab 101, and the separator 103 together around a winding axis.

[0096] The negative electrode tab 101 includes a negative electrode main body 1013 and a negative electrode tab 1012, and the negative electrode tab 1012 is protruded from the negative electrode main body 1013. The negative electrode main body 1013 includes a negative electrode active material layer 1011.

[0097] The negative electrode tab 101 includes a negative electrode main body 1013 and a negative electrode tab 1012, and the negative electrode tab 1012 is protruded from the negative electrode main body 1013. The negative electrode main body 1013 includes a negative electrode active material layer 1011.

[0098] The negative electrode tab 1012 includes a plurality of negative electrode tabs 1012, and the plurality of negative electrode tabs 1012 are connected to the long side of the negative electrode main body 1013 and are arranged at intervals.

[0099] The plurality of negative tabs 1012 are arranged at intervals along a winding direction of the negative main body portion 1013. The plurality of negative tabs 1012 can be arranged on opposite sides or on a single side of the negative main body portion 1013 along the winding axis. The winding direction of the negative main body portion 1013 can be the length direction of the negative main body portion 1013.

[0100] The plurality of negative tabs 1012 and the negative main body portion 1013 can be integrally formed. The negative tab 1012 and the negative main body portion 1013 can be cut and made by a die-cutting process.

[0101] In some embodiments, the interval distance between adjacent negative tabs 1012 increases along the winding direction of the negative main body portion 1013, i.e., from the first portion to the second portion. It can be understood that as the number of winding layers increases, the winding radius gradually increases, and a structure in which the plurality of negative tabs 1012 overlap and are stacked can be formed after winding is completed.

[0102] The positive tab 102 includes a positive main body portion 1023 and a positive tab 1022. The positive tab 1022 protrudes from the positive main body portion 1023. The positive main body portion 1023 includes a positive active material layer.

[0103] The positive tab 1022 includes a plurality of positive tabs 1022. The plurality of positive tabs 1022 are connected to the long side of the positive main body portion 1023, and the plurality of positive tabs 1022 are arranged at intervals.

[0104] The plurality of positive tabs 1022 are arranged at intervals along a winding direction of the positive main body portion 1023. The plurality of positive tabs 1022 can be arranged on opposite sides or on a single side of the positive main body portion 1023 along the winding axis. The winding direction of the positive main body portion 1023 can be the length direction of the positive main body portion 1023.

[0105] The plurality of positive tabs 1022 and the positive main body portion 1023 can be integrally formed. The positive tab 102 and the positive main body portion 1023 can be cut and made by a die-cutting process.

[0106] In some embodiments, the interval distance between adjacent positive tabs 1022 increases along the winding direction of the positive main body portion 1023. It can be understood that as the number of winding layers increases, the winding radius gradually increases, and a structure in which the plurality of positive tabs 1022 overlap and are stacked can be formed after winding is completed.

[0107] The winding axis direction is perpendicular to the winding direction.

[0108] The positive tab 102 has a first portion 104 extending from an innermost circle to an outermost circle, a second portion 105 extending from the outermost circle to the innermost circle, and a third portion 106 between the first portion 104 and the second portion 105.

[0109] In the embodiment, the first portion 104, the third portion 106 and the second portion 105 are sequentially distributed from inside to outside of the electrode assembly 100 along the winding direction. After the electrode assembly 100 is wound, the first portion 104 is located at the innermost circle of the electrode assembly 100 relative to the third portion 106, and the third portion 106 is located at the innermost circle of the electrode assembly 100 relative to the second portion 105.

[0110] The first portion 104 is close to the inlet portion, and the second portion 105 is close to the cutting portion. The first portion 104 and the second portion 105 have smaller tension, and the risk of deflection of the first portion 104 and the second portion 105 is greater than that of the third portion 106.

[0111] In some embodiments, the first portion of the positive electrode tab 102 can be n circles extending from the innermost circle to the outermost circle. The number n of the winding turns of the first portion around the winding axis satisfies: 1≤n≤5. For example, n can be 1, 2, 3, 4.5 or 5 turns.

[0112] In some embodiments, the second portion of the positive electrode tab 102 can be z circles extending from the outermost circle to the innermost circle. The number z of the winding turns of the second portion around the winding axis satisfies: 1≤z≤5. For example, z can be 1, 2, 3, 4.5 or 5 turns.

[0113] For example, as shown in FIG. 1, the first portion 104 of the positive electrode tab 102 is the innermost circle after the positive electrode main body 1023 is wound one turn along the winding direction. The boundary between the innermost circle and the second innermost circle of the positive electrode main body 1023 corresponds to the innermost end of the positive electrode main body 1023 along the distribution direction of the multi-layer positive electrode main body 1023. Figure 5 For example, as shown in FIG. 1, the first portion 104 of the positive electrode tab 102 is the innermost circle after the positive electrode main body 1023 is wound one turn along the winding direction. The boundary between the innermost circle and the second innermost circle of the positive electrode main body 1023 corresponds to the innermost end of the positive electrode main body 1023 along the distribution direction of the multi-layer positive electrode main body 1023.

[0114] Figure 5 For example, as shown in FIG. 1, the first portion 104 of the positive electrode tab 102 is the innermost circle after the positive electrode main body 1023 is wound one turn along the winding direction. The boundary between the innermost circle and the second innermost circle of the positive electrode main body 1023 corresponds to the innermost end of the positive electrode main body 1023 along the distribution direction of the multi-layer positive electrode main body 1023.

[0115] For example, as shown in FIG. 1, the first portion 104 of the positive electrode tab 102 is the innermost circle after the positive electrode main body 1023 is wound one turn along the winding direction. The boundary between the innermost circle and the second innermost circle of the positive electrode main body 1023 corresponds to the innermost end of the positive electrode main body 1023 along the distribution direction of the multi-layer positive electrode main body 1023. Figure 5 For example, as shown in FIG. 1, the first portion 104 of the positive electrode tab 102 is the innermost circle after the positive electrode main body 1023 is wound one turn along the winding direction. The boundary between the innermost circle and the second innermost circle of the positive electrode main body 1023 corresponds to the innermost end of the positive electrode main body 1023 along the distribution direction of the multi-layer positive electrode main body 1023.

[0116] ​The second part 105 of the positive electrode main body 1023 is the outermost ring after the positive electrode main body 1023 is wound once in the winding direction. The dividing point between the outermost ring and the second outermost ring of the positive electrode main body 1023 corresponds to the outermost end of the positive electrode main body 1023 along the distribution direction of the multilayer positive electrode main body 1023.

[0117] The outermost end of the negative electrode main body 1013 and the outermost end of the positive electrode main body 1023 can be aligned along the distribution direction of the multilayer positive electrode main body 1023, or the outermost end of the negative electrode main body 1013 can extend beyond the outermost end of the positive electrode main body 1023 along the winding direction.

[0118] like Figure 5 As shown, the dashed line is a partial dividing line. The third part 106 of the negative electrode main body 1013 is located between the first part 104 and the second part 105. The third part 106 of the negative electrode main body 1013 may include one or more turns wound around the winding axis. The third part 106 of the positive electrode main body 1023 is located between the first part 104 and the second part 105. The third part 106 of the positive electrode main body 1023 may include one or more turns wound around the winding axis.

[0119] In the first part 104, in a direction parallel to the winding axis of the winding structure, the height difference between the positive electrode active material layer 1021 and the negative electrode active material layer 1011 in the first part is H1, the height difference between the positive electrode active material layer 1021 and the negative electrode active material layer 1011 in the second part is H2, and the height difference between the positive electrode active material layer 1021 and the negative electrode active material layer 1011 in the third part is H3.

[0120] like Figure 12 As shown, the height of the positive electrode active material layer 1021 is h1, the height of the negative electrode active material layer 1011 is h2, and the height difference between the positive electrode active material layer 1021 and the negative electrode active material layer 1011 is h2-h1.

[0121] Before the electrode assembly 100 is wound, the heights of the positive electrode active material layer 1021 and the negative electrode active material layer 1011, as well as the height difference between the positive electrode active material layer 1021 and the negative electrode active material layer 1011 at the first part, can be measured by an X-ray areal density meter. After the electrode assembly 100 is wound, the heights of the positive electrode active material layer 1021 and the negative electrode active material layer 1011, as well as the height difference between the positive electrode active material layer 1021 and the negative electrode active material layer 1011 at the first part, can be measured by CT computed tomography.

[0122] The height of the positive electrode active material layer 1021 is the height of the portion of the positive electrode main body 1023 without the positive electrode tab 1022, and the height of the negative electrode active material layer 1011 is the height of the portion of the negative electrode main body 1013 without the negative electrode tab 1012.

[0123] In some embodiments, such as Figure 12 As shown, H1, H3, and H2 all satisfy: H1≥0, H3≥0, and H2≥0. That is, in the first part 104, the second part 105, and the third part 106 of the entire electrode assembly 100, the height of the negative electrode active material layer 1011 along the winding axis is greater than or equal to the height of the positive electrode active material layer 1021 along the winding axis. This reduces the lithium plating phenomenon caused by the offset and misalignment of the positive electrode 102 and the negative electrode 101 during the winding process, and also improves the contact stability between the negative electrode 101 and the overall performance of the battery.

[0124] For example, the height of the negative electrode active material layer 1011 along the winding axis is greater than or equal to the height of the positive electrode active material layer 1021 along the winding axis, as shown in the example. Figures 7 to 10 The height of the negative electrode active material layer 1011 along the winding axis is widened as shown in the diagram. Alternatively, it can be done as follows: Figure 11 The height of the positive electrode active material layer 1021 along the winding axis is reduced and narrowed as shown.

[0125] In particular, the negative electrode active material layer 1011 and the positive electrode active material layer 1021 in the first part 104, the second part 105 and the third part 106 can have the same width along the winding axis to reduce the processing difficulty.

[0126] Among them, H1, H3, and H2 of electrode assembly 100 can at least satisfy the following numerical relationships:

[0127] First, H1 > H3, and H2 > H3.

[0128] In this embodiment, by setting H1 > H3 and H2 > H3, the negative electrode active material layer 1011 can be left with an area margin relative to the positive electrode active material layer 1021 in both the first part 104 and the second part 105 where the tension of the electrode assembly 100 is relatively small. This effectively reduces the lithium plating phenomenon caused by the misalignment of the negative electrode active material layer 1011 and the positive electrode active material layer 1021 in the first part 104 and the second part 105 during the winding process.

[0129] In the present numerical relationship, in the case of H1>H3 and H2>H3, the negative electrode active material layer 1011 in the first portion 104 includes N segments distributed along the winding direction, the negative electrode active material layer 1011 in the first portion 104 is divided into N segments along the positions of the negative electrode tabs 1012, and the negative electrode tabs 1012 are arranged between adjacent two segments.

[0130] wherein the innermost end of the negative electrode active material layer 1011 can be provided with a negative electrode tab 1012, and then from the negative electrode tab 1012 at the innermost end to the second negative electrode tab 1012 is a segment; or the innermost end of the negative electrode active material layer 1011 is not provided with a negative electrode tab 1012, and then from the innermost end of the negative electrode main part 1013 to the first negative electrode tab 1012 is a segment.

[0131] wherein the innermost end of the positive electrode main part 1023 can be provided with a positive electrode tab 1022, and then from the positive electrode tab 1022 at the innermost end to the second positive electrode tab 1022 is a segment; or the innermost end of the positive electrode main part 1023 is not provided with a positive electrode tab 1022, and then from the innermost end of the positive electrode main part 1023 to the first positive electrode tab 1022 is a segment.

[0132] In the present embodiment, the second portion 105 includes at least one negative electrode tab 1012, in the case that the negative electrode tab 101 of the second portion 105 includes one negative electrode tab 1012, the negative electrode active material layer 1011 includes at least two segments; in the case that the negative electrode tab 101 of the second portion 105 includes N-1 negative electrode tabs 1012, the negative electrode active material layer 1011 includes at least N segments.

[0133] In the direction from the third portion 106 to the first portion 104, i.e. the winding direction of the electrode assembly 100 from inside to outside, the height of the negative electrode active material layer 1011 of each segment of the negative electrode active material layer 1011 along the winding axis direction is monotonically non-decreasing.

[0134] wherein the height of the segment of the negative electrode active material layer closest to the third portion along the winding axis direction is less than or equal to the height of the segment of the negative electrode active material layer farthest from the third portion along the winding axis direction.

[0135] It can be understood that in the first portion 104, the tension of each segment of the negative electrode active material layer 1011 is negatively correlated with the distance of each segment to the third portion 106, the smaller the tension of each segment, the more prone the position of each segment to be skewed in the winding process.

[0136] By setting the height of each segment of the negative electrode active material layer 1011 of the first portion 104 to be monotonically non-decreasing in the direction from the third portion 106 to the first portion 104, the risk of the negative electrode active material layer 1011 of the first portion 104 being offset relative to the positive electrode active material layer 1021 during winding can be reduced.

[0137] In the first portion 104, the height of each segment of the negative electrode active material layer 1011 along the winding axis can have the following structures:

[0138] First, in the first portion 104, the height of one segment of the negative electrode active material layer 1011 adjacent to another segment along the winding axis direction is less than the height of the other segment along the winding axis direction.

[0139] In the present embodiment, the height of each segment of the negative electrode active material layer 1011 of the negative electrode active material layer 1011 gradually increases in the direction from the third portion 106 to the first portion 104, which reduces the risk of the negative electrode active material layer 1011 being offset relative to the positive electrode active material layer 1021 during winding, while reducing costs.

[0140] In the first portion 104, the height of each segment of the negative electrode active material layer 1011 along the winding axis can have the following structures: Figures 7-10 In some embodiments, the difference between the height of one segment of the negative electrode active material layer 1011 of the first portion 104 facing away from the third portion 106 along the winding axis direction and the height of the second portion 105 along the winding axis direction is less than 5%, which takes into account processing errors and reduces processing difficulty.

[0141] It should be noted that the segment between adjacent negative electrode tabs 1012 on the negative electrode active material layer 1011 of the first portion 104 is formed by a single die cutting process, and the segment between the second portion 105 and the segment of the first portion 104 facing away from the third portion 106 is also formed by a single die cutting process, which forms a segment of two adjacent negative electrode tabs 1012 with substantially equal widths.

[0142] Second, as shown in Figure 7 and Figure 9 The difference between the height of each segment of the negative electrode active material layer 1011 of the first portion 104 along the winding axis direction is less than 5%.

[0143] In the present embodiment, in the case where the height of the negative electrode active material layer 1011 of the first portion 104 is substantially equal, the height of the negative electrode active material layer 1011 of the first portion 104 is substantially equal to the height of the negative electrode active material layer 1011 of the second portion 105.

[0144] Exemplarily, the difference in the height of each section of the negative active material layer 1011 in the first portion 104 along the winding axis direction can be 0, 1%, 3%, or 4%.

[0145] In this embodiment, considering the machining error, the height of each section of the negative active material layer 1011 in the first portion 104 along the winding axis direction is substantially equal, which can reduce the machining difficulty.

[0146] In this embodiment, as shown in Figure 7 and Figure 8 , in the case where the height of each section of the negative active material layer 1011 in the first portion 104 along the winding axis direction is substantially equal, the height of the negative active material layer 1011 in the first portion 104 is substantially equal to the height of the negative active material layer 1011 in the widened region of the second portion 105.

[0147] In the case where the height of the negative active material layer 1011 in the first portion 104 along the winding axis direction is equal to the height of the negative active material layer 1011 in the widened region of the second portion 105, the widened region of the second portion 105 can be arranged on the side where the negative tab 1012 is arranged, which can realize mass production and improve production efficiency; in the case where the height of the negative active material layer 1011 in the first portion 104 along the winding axis direction is equal to the height of the negative active material layer 1011 in the second portion 105, which can realize mass production and improve production efficiency.

[0148] It should be noted that since the negative tab 101 or the positive tab 102 is produced by a one-cut die cutting process, before being cut, the second portion 105 of the previous negative tab 101 and the first portion 104 of the next negative tab 101 can be cut by one-cut die cutting, so there is a case where the height of the first portion 104 and the second portion 105 of the same negative tab 101 is greater than the height of the third portion 106, and the first portion 104 and the second portion 105 are equal in width.

[0149] Exemplarily, as shown in Figure 7 , the widened region of the negative active material layer 1011 in the first portion 104 and the second portion 105 can be arranged on the side where the negative tab 1012 is arranged; or, as shown in Figure 8 , the widened region of the negative active material layer 1011 in the first portion 104 and the second portion 105 can be arranged on the side where the negative tab 1012 is not arranged.

[0150] Exemplarily, as shown in Figure 9 , the widened region of the negative active material layer 1011 in the first portion 104 can be arranged on the side where the negative tab 1012 is arranged; or, as shown in Figure 10As shown, the negative electrode active material layer 1011 can be disposed on the side where the negative electrode tab 1012 is not disposed in the widened area of ​​the first part 104.

[0151] Third, along the direction from the third part 106 to the first part 104, the height of each segment of the negative electrode active material layer 1011 in the first part 104 can remain unchanged at first and then gradually increase.

[0152] In this embodiment, H1 > H3 can be understood in at least the following ways:

[0153] First, along the winding direction, while the height of the positive electrode active material layer 1021 along the winding axis remains unchanged, the height of the negative electrode active material layer 1011 in the first part 104 along the winding axis is greater than the height of the negative electrode active material layer 1011 in the third part 106 along the winding axis.

[0154] Second, along the winding direction, while the height of the negative electrode active material layer 1011 along the winding axis remains unchanged, the height of the positive electrode active material layer 1021 located in the first part 104 along the winding axis is less than the height of the positive electrode active material layer 1021 located in the third part 106 along the winding axis.

[0155] Third, along the winding direction, when the heights of both the positive electrode active material layer 1021 and the negative electrode active material layer 1011 along the winding axis change, the height difference H1 between the negative electrode active material layer 1011 and the positive electrode active material layer 1021 along the winding axis in the first part 104 is greater than the height difference H3 between the negative electrode active material layer 1011 and the positive electrode active material layer 1021 along the winding axis in the third part 106.

[0156] In this embodiment, H2 > H3 can be understood in at least the following ways:

[0157] First, along the winding direction, while the height of the positive electrode active material layer 1021 along the winding axis remains unchanged, the height of the negative electrode active material layer 1011 in the second part 105 along the winding axis is greater than the height of the negative electrode active material layer 1011 in the third part 106 along the winding axis.

[0158] Second, such as Figure 7 As shown, along the winding direction, with the height of the negative electrode active material layer 1011 along the winding axis remaining unchanged, the height of the positive electrode active material layer 1021 located in the second part 105 along the winding axis is less than the height of the positive electrode active material layer 1021 located in the third part 106 along the winding axis.

[0159] Third, in the case where the height of the positive active material layer 1021 and the height of the negative active material layer 1011 in the winding axis direction are changed in the winding direction, the difference H2 between the height of the negative active material layer 1011 in the winding axis direction and the height of the positive active material layer 1021 in the winding axis direction at the first portion 104 is greater than the difference H3 between the height of the negative active material layer 1011 in the winding axis direction and the height of the positive active material layer 1021 in the winding axis direction at the third portion 106.

[0160] In the case where the height of the positive active material layer 1021 in the winding axis direction at the first portion 104 is unchanged, the height of the negative active material layer 1011 in the winding axis direction can decrease stepwise from the winding start section of the first portion 104 to the direction of the third portion 106, so as to reduce the cost while reducing the axial length of the electrode assembly 100.

[0161] In the case where the height of the negative active material layer 1011 in the winding axis direction at the first portion 104 is unchanged, the height of the positive active material layer 1021 in the winding axis direction can increase stepwise from the winding start section of the first portion 104 to the direction of the third portion 106.

[0162] In some embodiments, the electrode assembly 100 satisfies: 0.01mm≤H1-H3≤2mm.

[0163] For example, H1-H3 can be 0.01-2mm, 0.1-0.8mm, or 1-1.5mm.

[0164] For example, H1-H3 can be 0.05mm, 0.1mm, 0.12mm, 0.5mm, 1mm, 1.1mm, 1.5mm, or 2mm.

[0165] In the case where the height of one section of the negative active material layer 1011 of the first portion 104 close to the third portion 106 is less than the height of another section in the winding axis direction among any two adjacent sections of the negative active material layer 1011 of the first portion 104, the sections of the negative active material layer 1011 of the first portion 104 are sequentially named as the first section, the second section, the third section, and so on in the arrangement direction from the first portion 104 to the third portion 106, taking the adjacent negative tab 1012 of the first portion 104 as one section. For example, the first section is widened by 0.6mm, the second section is widened by 0.4mm, and the third section is widened by 0.2mm, sequentially decreasing; or the first section is widened by 1mm, the second section is widened by 0.8mm, and the third section is widened by 0.6mm, sequentially decreasing.

[0166] H2>H3, wherein H2 is the difference between the height of the negative active material layer 1011 in the second portion 105 along the winding axis direction and the height of the positive active material layer 1021 in the second portion 105 along the winding axis direction, and H3 is the difference between the height of the negative active material layer 1011 in the third portion 106 along the winding axis direction and the height of the positive active material layer 1021 in the third portion 106 along the winding axis direction.

[0167] After the electrode assembly 100 is wound, the third portion 106 is located at the inner circle of the electrode assembly 100 after the negative electrode tab 101 is wound.

[0168] In the second portion 105, the height of the negative active material layer 1011 along the winding axis direction can be equal to, less than, or greater than the height of the negative active material layer 1011 in the first portion 104 along the winding axis direction, as long as the height of the negative active material layer 1011 in the second portion 105 along the winding axis direction is greater than the height of the positive active material layer 1021 in the second portion 105 along the winding axis direction.

[0169] The relationship between H1 and H3 can satisfy H1=H2, H1>H2, or H1

[0170] For example, in the case where the height of each segment of the negative active material layer 1011 in the first portion 104 along the winding axis direction is equal, the height of the negative active material layer 1011 in the second portion 105 along the winding axis direction can be equal to the height of the negative active material layer 1011 in the first portion 104 along the winding axis direction; in the case where the height of each segment of the negative active material layer 1011 in the first portion 104 along the winding axis direction is positively correlated with the distance from the third portion 106, the height of the negative active material layer 1011 in the first portion 104 and the second portion 105 along the winding axis direction is greater than the height of the negative active material layer 1011 in the third portion 106 along the winding axis direction.

[0171] In the related art, the second portion 105 is subjected to a smaller tension than the third portion 106 when cut, and the second portion 105 is more likely to deviate relative to the third portion 106.

[0172] In the embodiment, by setting H2>H3, the height of the negative active material layer 1011 in the second part 105 can be increased or the height of the positive active material layer 1021 in the second part 105 can be reduced, the area allowance of the negative active material layer 1011 in the second part 105 in the height direction can be increased, and in the process of stacking and winding the negative electrode sheet 101 and the positive electrode sheet 102 in the embodiment, even if the positive active material layer 1021 or the negative active material layer 1011 in the second part 105 is shifted due to smaller tension, the risk of misalignment of the positive active material layer 1021 or the negative active material layer 1011 can be reduced, which helps to reduce the lithium precipitation phenomenon caused by the misalignment of the positive active material layer 1021 or the negative active material layer 1011 in the winding process, and also improves the contact stability between the negative electrode sheets 101 and the overall performance of the battery.

[0173] Secondly, H1>H3.

[0174] As shown in Figure 9 and Figure 10 In the embodiment, by setting H1>H3, the negative active material layer 1011 in the first part 104 of the electrode assembly 100 with smaller tension can have an area allowance relative to the positive active material layer 1021, which effectively reduces the lithium precipitation phenomenon caused by the misalignment of the negative active material layer 1011 and the positive active material layer 1021 in the first part 104 in the winding process.

[0175] In the numerical relationship, in the case of H1>H3, in the first part 104, the negative active material layer 1011 includes N segments distributed along the winding direction, the negative active material layer 1011 in the first part 104 is divided into N segments along the position of the negative tab 1012, and the negative tab 1012 is arranged between the adjacent two segments.

[0176] In the direction from the third part 106 to the first part 104, i.e. the winding direction of the electrode assembly 100 from inside to outside, the height of each segment of the negative active material layer 1011 along the winding axis direction is monotonically non-decreasing.

[0177] Among them, the height of the segment of the negative active material layer closest to the third part along the winding axis direction is less than or equal to the height of the segment of the negative active material layer farthest from the third part along the winding axis direction.

[0178] It can be understood that in the first part 104, the tension on each segment of the negative active material layer 1011 is negatively correlated with the distance of each segment to the third part 106, and the smaller the tension on each segment, the more prone the position of each segment to be skewed in the winding process.

[0179] By setting the height of each segment of the negative electrode active material layer 1011 of the first portion 104 to be monotonically non-decreasing in the direction from the third portion 106 to the first portion 104, the risk of the segments of the negative electrode active material layer 1011 of the first portion 104 being offset relative to the positive electrode active material layer 1021 during winding can be reduced.

[0180] In the first portion 104, the height of each segment of the negative electrode active material layer 1011 along the winding axis can have the following structures:

[0181] First, in the first portion 104, the height of one segment of the negative electrode active material layer 1011 adjacent to another segment in the direction along the winding axis is less than the height of the other segment in the direction along the winding axis.

[0182] In the present embodiment, the height of each segment of the negative electrode active material layer 1011 gradually increases in the direction from the third portion 106 to the first portion 104, which reduces the risk of the segments of the negative electrode active material layer 1011 being offset relative to the positive electrode active material layer 1021 during winding, while reducing costs.

[0183] In some embodiments, the height of each segment of the negative electrode active material layer 1011 in the first portion 104 in the direction along the winding axis is less than 5% of the height of each segment of the negative electrode active material layer 1011 in the second portion 105 in the direction along the winding axis. Figure 7 Figure 8 In some embodiments, the difference between the height of one segment of the negative electrode active material layer 1011 in the first portion 104 away from the third portion 106 in the direction along the winding axis and the height of the second portion 105 in the direction along the winding axis is less than 5%, which takes into account processing errors and reduces processing difficulty.

[0184] It should be noted that the segment between adjacent negative electrode tabs 1012 on the negative electrode active material layer 1011 in the first portion 104 is formed by a single die cutting process, and the segment between the first portion 104 away from the third portion 106 and the second portion 105 of the negative electrode active material layer 1011 is also formed by a single die cutting process, which forms a segment of two adjacent negative electrode tabs 1012 with substantially equal widths.

[0185] Second, as shown in Figure 7 and Figure 8 , the difference between the height of each segment of the negative electrode active material layer 1011 in the first portion 104 in the direction along the winding axis is less than 5%.

[0186] In the present embodiment, in the case where the height of the negative electrode active material layer 1011 in the first portion 104 is substantially equal, the height of the negative electrode active material layer 1011 in the first portion 104 is substantially equal to the height of the negative electrode active material layer 1011 in the second portion 105.

[0187] ​Exemplarily, the difference in height of each section of the negative active material layer 1011 of the first portion 104 in the winding axis direction can be 0, 1%, 3%, or 4%.

[0188] In this embodiment, considering the machining error, the height of each section of the negative active material layer 1011 of the first portion 104 in the winding axis direction is substantially equal, which can reduce the machining difficulty.

[0189] In this embodiment, in the case where the height of each section of the negative active material layer 1011 of the first portion 104 in the winding axis direction is substantially equal, the height of the negative active material layer 1011 of the first portion 104 is substantially equal to that of the second portion 105.

[0190] In this embodiment, in the case where the height of each section of the negative active material layer 1011 of the first portion 104 in the winding axis direction is substantially equal, the height of the negative active material layer 1011 of the first portion 104 is substantially equal to that of the second portion 105.

[0191] It should be noted that since the negative electrode sheet 101 or the positive electrode sheet 102 is produced by one-cut die cutting process, before being cut, the second portion 105 of the previous negative electrode sheet 101 and the first portion 104 of the next negative electrode sheet 101 can be cut by one-cut die cutting, so there is a case where the height of the first portion 104 and the third portion 106 of the same negative electrode sheet 101 is greater than that of the second portion 105, and the first portion 104 and the second portion 105 are equal in width.

[0192] Third, in the direction from the third portion 106 to the first portion 104, the height of each section of the negative active material layer 1011 of the first portion 104 can first remain unchanged and then gradually increase.

[0193] In this embodiment, the understanding of H1>H3 is the same as that in the above-mentioned embodiment of H1>H3 and H2>H3, which will not be repeated here.

[0194] Third, H2>H3.

[0195] In this embodiment, by setting H2>H3, the negative active material layer 1011 can be left with an area allowance relative to the positive active material layer 1021 in the second portion 105 with smaller tension of the electrode assembly 100, effectively reducing the lithium precipitation phenomenon caused by the misalignment of the negative active material layer 1011 and the positive active material layer 1021 in the second portion 105 during winding.

[0196] As Figure 9 shown, in the case of H2>H3, the negative active material layer 1011 includes N segments distributed along the winding direction, and the negative tab 1012 is arranged between adjacent two segments in the second part 105.

[0197] Wherein, the outermost end of the negative active material layer 1011 can be provided with the negative tab 1012, and then the segment is from the negative tab 1012 of the outermost end to the previous negative tab 1012; or the outermost end of the negative active material layer 1011 is not provided with the negative tab 1012, and then the segment is from the outermost end of the negative active material layer 1011 to the previous negative tab 1012.

[0198] Wherein, the outermost end of the negative active material layer 1011 can be provided with the negative tab 1012, and then the segment is from the negative tab 1012 of the outermost end to the previous negative tab 1012; or the outermost end of the negative active material layer 1011 is not provided with the negative tab 1012, and then the segment is from the outermost end of the negative active material layer 1011 to the previous negative tab 1012.

[0199] In this embodiment, the second part 105 includes at least one tab, and in the case that the negative tab 101 of the second part 105 includes one tab, the negative active material layer 1011 includes at least two segments; in the case that the negative tab 101 of the second part 105 includes N-1 tabs, the negative active material layer 1011 includes at least N segments.

[0200] In this embodiment, the difference of the height of each segment of the negative active material layer 1011 along the winding axis direction is less than 5%, and the height of the negative active material layer 1011 of the second part 105 is basically equal.

[0201] For example, the difference of the height of each segment of the negative active material layer 1011 of the second part 105 along the winding axis direction can be 0, 1%, 3% or 4%.

[0202] In this embodiment, considering the processing error, the height of each segment of the negative active material layer 1011 of the second part 105 along the winding axis direction is basically equal, which can reduce the processing difficulty.

[0203] It should be noted that since the negative tab 101 or the positive tab 102 is produced by one knife die cutting process, before being cut, the second part 105 of the previous negative tab 101 and the first part 104 of the adjacent next negative tab 101 can be cut by one knife die, so there is a case that the height of the first part 104 and the third part 106 of the same negative tab 101 is greater than the height of the second part 105, and the first part 104 and the second part 105 are equal in width.

[0204] In this embodiment, the understanding of H2>H3 is the same as that in the above-mentioned embodiment of H1>H3 and H2>H3, and no repeated description is made here.

[0205] At present, in the winding or laminating process of the negative active material layer 1011 or the positive active material layer 1021, appropriate tension control is required in the feeding and cutting stages, which can reduce the deviation of the negative active material layer 1011 and the positive active material layer 1021 in the winding process. However, in the winding process of the negative active material layer 1011 or the positive active material layer 1021, the part of the negative active material layer 1011 or the positive active material layer 1021 fed and cut has no tension or small tension, and the negative active material layer 1011 or the positive active material layer 1021 will deviate and dislocate, causing the dislocation of the negative active material layer 1011 or the positive active material layer 1021 in the inner circle of the winding, and leading to the lithium precipitation phenomenon of the negative electrode sheet 101.

[0206] According to the battery cell 12 provided in the embodiments of the present application, the negative active material layer 1011 and the positive active material layer 1021 are arranged in a special size relationship, the first part and the second part 105 are subjected to small tension during feeding and cutting, the first part 104 and the second part 105 are more prone to deviation relative to the third part, and the height difference of the negative active material layer 1011 and the positive active material layer 1021 of the first part 104 and the second part 105 is increased. In the process of laminating and winding the negative electrode sheet 101 and the positive electrode sheet 102 in the present embodiment, the negative active material layer 1011 of the first part 104 and the second part 105 leaves a large area allowance in the height direction, so that even if the negative active material layer 1011 and the positive active material layer 1021 of the first part 104 and the second part 105 deviate due to small tension, the dislocation risk of the negative active material layer 1011 and the positive active material layer 1021 can be reduced, which helps to reduce the lithium precipitation phenomenon caused by the deviation and dislocation of the negative active material layer 1011 and the positive active material layer 1021 in the winding process, and also improves the contact stability between adjacent negative active material layers 1011 and the overall performance of the battery.

[0207] According to some embodiments of the present application, the negative electrode sheet 101 satisfies 1≤M≤10, where M is the number of negative tabs 1012 arranged on one side of the negative active material layer 1011 of the first part 104, that is, the negative active material layer 1011 of the first part 104 can be M+1 segments.

[0208] In this embodiment, the number M of negative tabs 1012 arranged on one side of the negative active material layer 1011 of the first part 104 can be 1, 2, 5 or 10.

[0209] In the embodiment, at least one negative tab 1012 is provided after the negative active material layer 1011 is wound around the winding axis for one turn, in other words, after the negative electrode sheet 101 is wound, the first part of the negative active material layer 1011 can be wound for the first to tenth turns from the inside to the outside of the electrode assembly 100.

[0210] By setting the number of negative tabs 1012 on one side of the first part of the negative active material layer 1011, the length of the negative active material layer 1011 in the first part 104 can be limited, which can compensate for the adverse effects of the misalignment of the positive active material layer 1021 and the negative active material layer 1011 in the first part 104 due to the lack of tension during winding, and also achieve balanced distribution of current and energy.

[0211] According to some embodiments of the present application, the separator 103 includes a protection section 1031 beyond the winding end section of the negative electrode sheet 101 along the winding direction of the electrode assembly 100, and the number of winding turns m of the protection section 1031 along the winding direction satisfies: m≥0.5.

[0212] Wherein, m can be 0.5, 2, 3 or a larger value, by increasing the protection section beyond the end section of the negative electrode sheet 101, the edge or end section of the negative electrode sheet 101 will not be directly exposed to the electrolyte or other environments that may cause short circuit or damage, at the same time, the end section of the negative electrode sheet 101 can be restrained, thereby providing sufficient physical barrier and electrochemical isolation for the end section, and increasing the safety and stability of the battery.

[0213] According to some embodiments of the present application, the present application also provides a battery device, which includes a plurality of battery monomers 12.

[0214] According to some embodiments of the present application, the present application also provides an energy storage device, which includes a plurality of battery monomers 12 or a plurality of battery devices, and the battery monomers 12 or the battery devices are used for storing or providing electric energy.

[0215] According to some embodiments of the present application, the present application also provides an energy storage system, which includes a power conversion device and an energy storage device, and the power conversion device is used for electrically connecting a power generation device and the energy storage device.

[0216] According to some embodiments of the present application, the present application also provides a power consumption device, which includes a battery monomer 1212, a battery device, an energy storage device or an energy storage system, and the battery monomer 12 or the battery device is used for storing or providing electric energy.

[0217] According to some embodiments of the present application, the present application also provides a charging network, which includes a charging pile and an energy storage device or an energy storage system, and the energy storage device is used for providing electric energy for the charging pile.

[0218] As Figures 5-12 shown in the following with a specific embodiment to illustrate the technical solutions of the present application.

[0219] The present application provides a battery monomer 12, the battery monomer 12 includes: a shell and an electrode assembly 100, the electrode assembly 100 is contained in the shell, the electrode assembly 100 includes positive pole sheet 102 and negative pole sheet 101, positive pole sheet 102 and negative pole sheet 101 are stacked, positive pole sheet 102 and negative pole sheet 101 jointly form a winding structure, positive pole sheet 102 includes positive pole main part 1023 and positive pole lug 1022, positive pole lug 1022 protrudes from positive pole main part 1023, positive pole main part 1023 includes positive pole active material layer 1021, negative pole sheet 101 includes negative pole main part 1013 and negative pole lug 1012, negative pole lug 1012 protrudes from negative pole main part 1013, negative pole main part 1013 includes negative pole active material layer 1011;Positive pole sheet 102 has first part 104 extending from the innermost circle to the outer circle, second part 105 extending from the outermost circle to the inner circle and third part between first part 104 and second part 105;In the direction parallel to the winding axis of the winding structure, the height difference of positive pole active material layer 1021 and negative pole active material layer 1011 at first part 104 is H1, the height difference of positive pole active material layer 1021 and negative pole active material layer 1011 at second part 105 is H2, and the height difference of positive pole active material layer 1021 and negative pole active material layer 1011 at third part is H3;Satisfy: H1> H3, and / or, H2> H3.

[0220] According to the battery monomer 12 provided by the embodiment of the present application, by setting H1> H3, and / or, H2> H3, the height of negative pole active material layer 1011 in the direction of winding axis in first part 104 and / or second part 105 can have a larger margin relative to the height of positive pole active material layer 1021 in the direction of winding axis, even if the position of negative pole active material layer 1011 and positive pole active material layer 1021 is offset due to the smaller tension of the battery monomer in first part 104 or second part 105, the risk of misplacement of negative pole active material layer 1011 and positive pole active material layer 1021 can be reduced, which helps to reduce the adverse effects caused by the offset of negative pole active material layer 1011 and positive pole active material layer 1021, and also improves the contact stability between adjacent layers of negative pole active material layer 1011 and the overall performance of the battery.

[0221] Among them, H1, H3, H2 of the electrode assembly 100 can at least satisfy the following numerical relationship:

[0222] First, H1> H3, and H2> H3.

[0223] In the present embodiment, by setting H1>H3 and H2>H3, the negative active material layer 1011 can be left with an area allowance relative to the positive active material layer 1021 in the first portion 104 and the second portion 105 of the electrode assembly 100 where the tension is small, and the phenomenon of lithium precipitation caused by misalignment of the negative active material layer 1011 and the positive active material layer 1021 in the first portion 104 and the second portion 105 during winding can be effectively reduced.

[0224] Secondly, H1>H3.

[0225] As shown in FIGS. 1 and 2, in the present embodiment, by setting H1>H3, the negative active material layer 1011 can be left with an area allowance relative to the positive active material layer 1021 in the first portion 104 of the electrode assembly 100 where the tension is small, and the phenomenon of lithium precipitation caused by misalignment of the negative active material layer 1011 and the positive active material layer 1021 in the first portion 104 during winding can be effectively reduced. Figure 9 Figure 10 Thirdly, H2>H3.

[0226] In the present embodiment, by setting H2>H3, the negative active material layer 1011 can be left with an area allowance relative to the positive active material layer 1021 in the second portion 105 of the electrode assembly 100 where the tension is small, and the phenomenon of lithium precipitation caused by misalignment of the negative active material layer 1011 and the positive active material layer 1021 in the second portion 105 during winding can be effectively reduced.

[0227] If not particularly specified, all the embodiments and optional embodiments of the present application can be combined to form new technical solutions.

[0228] If not particularly specified, all the technical features and optional technical features of the present application can be combined to form new technical solutions.

[0229] If not particularly specified, all the technical features and optional technical features of the present application can be combined to form new technical solutions.

[0230] The above merely provides preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.​

Claims

1. A battery cell, characterized by, The battery includes: a housing; an electrode assembly accommodated in the housing, the electrode assembly including a positive electrode tab and a negative electrode tab, the positive electrode tab and the negative electrode tab being stacked, the positive electrode tab and the negative electrode tab collectively forming a wound structure, the positive electrode tab including a positive electrode main body portion and a positive electrode tab lug, the positive electrode tab lug protruding from the positive electrode main body portion, the positive electrode main body portion including a positive electrode active material layer, the negative electrode tab including a negative electrode main body portion and a negative electrode tab lug, the negative electrode tab lug protruding from the negative electrode main body portion, the negative electrode main body portion including a negative electrode active material layer; the positive electrode tab has a first portion extending from an innermost coil to an outermost coil, a second portion extending from the outermost coil to the innermost coil, and a third portion between the first portion and the second portion; in a direction parallel to a winding axis of the wound structure, a height difference between the positive electrode active material layer and the negative electrode active material layer at the first portion is H1, a height difference between the positive electrode active material layer and the negative electrode active material layer at the second portion is H2, and a height difference between the positive electrode active material layer and the negative electrode active material layer at the third portion is H3; H1 > H3 and / or H2 > H3 are satisfied.

2. The battery cell of claim 1, wherein, In the case where H1 > H3 and H2 > H3, in the first portion, the negative electrode active material layer includes N segments distributed in a winding direction, the negative electrode tab is provided between adjacent two segments, in a direction from the third portion to the first portion, a height of a segment of the negative electrode active material layer closest to the third portion in the winding axis direction is less than or equal to a height of a segment of the negative electrode active material layer farthest from the third portion in the winding axis direction.

3. The battery cell of claim 2, wherein, In the first portion, a height of a segment of the negative electrode active material layer closer to the third portion in the winding axis direction is less than a height of another segment in the winding axis direction.

4. The battery cell of claim 3, wherein, A difference between a height of a segment of the negative electrode active material layer farthest from the third portion in the winding axis direction and a height of the second portion in the winding axis direction is less than 5%.

5. The battery cell of claim 2, wherein, In the first portion, a difference between heights of segments of the negative electrode active material layer in the winding axis direction is less than 5%.

6. The battery cell of any one of claims 2-5, wherein, 0.01 mm ≤ H1 - H3 ≤ 2 mm is satisfied.

7. The battery cell of claim 1, wherein, In the case where H1 > H3, in the first portion, the negative electrode active material layer includes N segments distributed in a winding direction, the negative electrode tab is provided between adjacent two segments, in a direction from the third portion to the first portion, a height of a segment of the negative electrode active material layer closest to the third portion in the winding axis direction is less than or equal to a height of a segment of the negative electrode active material layer farthest from the third portion in the winding axis direction.

8. The battery cell of claim 7, wherein, In the first portion, a height of a segment of the negative electrode active material layer closer to the third portion in the winding axis direction is less than a height of another segment in the winding axis direction.

9. The battery cell of claim 7, wherein, In the first part, the difference in height of each segment of the negative active material layer along the winding axis direction is less than 5%.

10. The battery cell of any one of claims 7-9, wherein, The following is satisfied: 0.01 mm≤H1-H3≤2 mm.

11. The battery cell of claim 1, wherein, In the case of H2>H3, in the second part, the negative active material layer includes N segments distributed along the winding direction, and the negative electrode tabs are arranged between adjacent two segments, and the difference in height of each segment of the negative active material layer along the winding axis direction is less than 5%.

12. The battery cell of any one of claims 1-11, wherein, The number of turns n of the first part around the winding axis satisfies: 1≤n≤5; and / or, the number of turns z of the second part around the winding axis satisfies: 1≤z≤5.

13. The battery cell of any one of claims 1-12, wherein, The electrode assembly further includes a separator film, and the positive electrode tab, the separator film and the negative electrode tab are stacked, and the positive electrode tab, the separator film and the negative electrode tab together form a winding structure, and along the winding direction, the separator film includes a protection segment beyond the winding ending segment of the negative electrode tab, and the number of turns m of the protection segment around the winding axis satisfies: m>0.

5.

14. A battery device comprising: A plurality of battery cells according to any one of claims 1-13.

15. An electrical device comprising a battery cell according to any one of claims 1-13.

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