Battery monomer, battery device and electric device

Abstract

The utility model provides a battery monomer, a battery device and a power utilization device. The battery monomer comprises a shell and an electrode assembly accommodated in the shell, the electrode assembly is formed by winding two pole pieces, the two pole pieces are respectively a first pole piece and a second pole piece, each pole piece comprises a pole lug and n bending sections which are overlapped and sequentially connected, n is greater than or equal to 2, the pole lugs and the bending sections in the first pole piece are arranged in one-to-one correspondence, and the bending sections in the second pole piece are arranged in one-to-one correspondence; the tabs in the second pole piece are connected with the m bent sections in a one-to-one correspondence manner, m is greater than or equal to 0.5 n and less than n, more tabs are arranged on each pole piece, so that the size between the adjacent tabs is reduced, the resistance of the pole pieces is reduced, the current distribution in the pole pieces is uniform, the lithium precipitation risk is reduced, and the reliability of a battery monomer is improved; and by adjusting the number of the tabs in the second pole piece, the number of the tabs is reduced under the condition of reducing the sizes of the adjacent tabs, so that the utilization rate of the internal space of the shell is improved, and the energy density of the single battery is improved.

Description

Technical Field

[0001] This application relates to the field of batteries, and in particular to a battery cell, a battery device, and an electrical device. Background Technology

[0002] Batteries are widely used in new energy vehicles, electronic devices, and other fields. As the demand for batteries increases, higher requirements are being placed on their reliability. Furthermore, as the market demands longer battery lifespans, the requirements for battery reliability are also rising. Utility Model Content

[0003] In view of the above problems, this application provides a battery cell, a battery device, and an electrical device that can improve the reliability of the battery cell.

[0004] In a first aspect, this application provides a battery cell, comprising: a housing; and an electrode assembly housed within the housing. The electrode assembly includes two wound electrodes, each electrode including a tab and n stacked and sequentially connected bending segments, where n ≥ 2. The two electrodes are a first electrode and a second electrode, respectively. In the first electrode, the tab and each bending segment are connected in a one-to-one correspondence, and in the second electrode, the tab and m bending segments are connected in a one-to-one correspondence, where 0.5n ≤ m < n.

[0005] In the technical solution of this application embodiment, the battery cell includes a housing and an electrode assembly housed within the housing. The electrode assembly is formed by winding two electrode sheets, which are respectively a first electrode sheet and a second electrode sheet. Each electrode sheet includes tabs and n bent segments stacked and connected in sequence, where n≥2. In the first electrode sheet, the tabs and each bent segment are arranged in a one-to-one correspondence. In the second electrode sheet, the tabs and m bent segments are connected in a one-to-one correspondence, where 0.5n≤m<n. By setting more tabs on each electrode sheet to reduce the size between adjacent tabs, the electrode sheet resistance is reduced, which helps to make the current distribution in the electrode sheet uniform, reduce the risk of lithium plating, and improve the reliability of the battery cell. Furthermore, by adjusting the number of tabs in the second electrode sheet, the number of tabs is reduced while reducing the size of adjacent tabs, thereby improving the utilization rate of the internal space of the housing and increasing the energy density of the battery cell.

[0006] In some embodiments, the first electrode is a negative electrode and the second electrode is a positive electrode.

[0007] In the technical solution of this application embodiment, during the charging process, lithium ions are embedded in the negative electrode sheet. Therefore, more tabs are set on the negative electrode sheet, the size of the negative electrode sheet between adjacent tabs is reduced, the resistance of the negative electrode sheet is reduced, the difficulty of lithium embedding in the negative electrode sheet is reduced, and the charging rate of the battery cell is improved.

[0008] In some embodiments, the second electrode includes a first part and a second part that are interconnected. The first part includes n1 bending segments and the second part includes n2 bending segments, where n1≥2 and n2≥2. In the first part, the electrode tab is connected to each bending segment in a one-to-one correspondence. In the second part, the electrode tab is connected to ceil(n2 / 2) bending segments in a one-to-one correspondence.

[0009] In the technical solution of this application embodiment, the second electrode includes two parts: a first part and a second part. The tabs are arranged regularly in the first part to reduce the overall processing difficulty of the second electrode.

[0010] In some embodiments, the first part includes n1 bends, n1 = floor(n / 2); the second part includes n2 bends, n2 = ceil(n / 2).

[0011] In the technical solution of this application embodiment, floor(n / 2) bending segments are set in the first part; ceil(n / 2) bending segments are set in the second part to reduce the processing difficulty of the electrode and to uniformly distribute the current in the second part.

[0012] In some embodiments, the first portion is closer to the center of the electrode assembly than the second portion.

[0013] In the technical solution of this application embodiment, the second part is located on the outside of the electrode assembly, and the first part is located on the inside of the electrode assembly. Relatively speaking, the outer electrode tab is relatively long, and reducing the number of outer electrode tabs helps to reduce the cost of electrode material.

[0014] In some embodiments, the second portion is closer to the center of the electrode assembly than the first portion.

[0015] In the technical solution of this application embodiment, the first part is located on the outside of the electrode assembly and the second part is located on the inside of the electrode assembly. Relatively speaking, the extension dimension of the outer bending section is longer. Therefore, more tabs are provided on the outside to reduce the spacing between adjacent tabs, reduce the internal resistance of the electrode sheet between adjacent tabs, help to make the current distribution in the electrode sheet uniform, reduce the risk of lithium plating, and improve the reliability of the battery cell.

[0016] In some embodiments, a bend is provided between adjacent tabs in the second part.

[0017] In the technical solution of this application embodiment, a bending section is provided between adjacent tabs. By arranging the tabs evenly, it helps to achieve a uniform current distribution on the electrode and reduce the risk of lithium plating on the electrode.

[0018] In some embodiments, the battery cell further includes an adapter mechanism, which includes a welding area, and the tab is welded to the welding area and the adapter mechanism. The area of ​​the welding area is S0, and the surface area of ​​the tab on one side in its thickness direction is S1, which satisfies 0.1≤S0 / S1≤1.

[0019] In the technical solution of this application embodiment, the tab is connected to the welding area of ​​the adapter mechanism. When the area of ​​the welding area and the surface area of ​​the tab on its thickness side meet the above conditions, the problem of insufficient overcurrent area between the tab and the adapter mechanism, which affects the fast charging capability of the battery cell, is improved.

[0020] In some embodiments, the welding area has a dimension L1 in the first direction and a dimension L2 in the second direction, satisfying 6≤L1 / L2≤7, the first direction and the second direction intersect, and the second direction is the extension direction of the tab.

[0021] In the technical solution of this application embodiment, when the dimensions of the welding area in the first direction and the dimensions in the second direction meet the above conditions, the problem of insufficient overcurrent area between the electrode and the adapter mechanism, which affects the fast charging capability of the battery cell, is improved.

[0022] Secondly, this application provides a battery device including the battery cell described in the first aspect embodiment above.

[0023] Thirdly, this application provides an electrical device including the battery device described in the second aspect embodiment above. Attached Figure Description

[0024] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0025] Figure 1 This is a schematic diagram of the structure of a vehicle provided in one embodiment of this application;

[0026] Figure 2 This is a schematic diagram of the structure of a battery device provided in an embodiment of this application;

[0027] Figure 3 This is a schematic diagram of the structure of a battery module provided in one embodiment of this application;

[0028] Figure 4 This is an exploded view of a single battery cell provided in an embodiment of this application;

[0029] Figure 5 This is a schematic diagram of the electrode assembly of a battery cell provided in an embodiment of this application;

[0030] Figure 6 This is a schematic diagram of the structure of the first electrode of a battery cell provided in an embodiment of this application;

[0031] Figure 7 This is a schematic diagram of the first part of the structure of the second electrode of a battery cell provided in an embodiment of this application;

[0032] Figure 8 This is a schematic diagram of the second part of the structure of the second electrode of a battery cell provided in an embodiment of this application;

[0033] Figure 9 This is a schematic diagram of the electrode assembly of a battery cell provided in an embodiment of this application;

[0034] Figure 10 This is a partial structural schematic diagram of a battery cell provided in an embodiment of this application;

[0035] Figure 11 This is a line graph showing the current density distribution of a battery cell with different tab configurations according to an embodiment of this application;

[0036] Figure 12 This is an impedance histogram of different tab arrangement methods for a single battery cell provided in an embodiment of this application;

[0037] Figure 13 This is a potential line graph of the scheme in Comparative Example 3 of this application;

[0038] Figure 14 This is a potential line graph of the embodiment scheme in this application.

[0039] Explanation of reference numerals in the attached figures:

[0040] 1. Vehicle; 101. Motor; 102. Controller;

[0041] 2. Battery assembly; 201. Battery module; 202. Housing; 2021. First housing; 2022. Second housing;

[0042] 3. Battery cells;

[0043] 4. Shell;

[0044] 5. Electrode assembly; 51. Electrode; 52. First electrode; 53. Second electrode; 511. Tab; 512. Bending section; 531. First part; 532. Second part; 54. Isolator;

[0045] 6. Top cover assembly;

[0046] 7. Adapter mechanism; 71. Welding area;

[0047] X, the first direction; Y, the second direction. Detailed Implementation

[0048] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0049] It should be noted that, unless otherwise stated, the technical or scientific terms used in the embodiments of this application should have the ordinary meaning understood by those skilled in the art to which the embodiments of this application pertain.

[0050] In the description of the embodiments of this application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0051] Furthermore, technical terms such as "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. In the description of the embodiments of this application, "a plurality of" means two or more, unless otherwise explicitly defined.

[0052] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0053] In the description of the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0054] Currently, judging from market trends, the application of power batteries is becoming increasingly widespread. Power batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but also extensively used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. With the continuous expansion of power battery applications, market demand is also constantly increasing.

[0055] Purple spots or lithium plating may appear during the charging process of a single battery cell, which reduces the reliability of the battery cell.

[0056] After the electrode sheets are wound into an electrode assembly, the outer layer and length of the electrode assembly gradually increase. In related technologies, the wound battery cell adopts a 1 / 2 tab method, that is, a tab is set for two adjacent bending sections. Because the large tab spacing will lead to an increase in the resistance of the electrode sheets, it will deteriorate the uniform distribution of current density during fast charging, and thus cause purple spots or lithium plating.

[0057] To address the aforementioned issues, this application provides a battery cell comprising a housing and an electrode assembly housed within the housing. The electrode assembly is formed by winding two electrode sheets, which are designated as a first electrode sheet and a second electrode sheet. Each electrode sheet includes tabs and n stacked and sequentially connected bending segments, where n ≥ 2. In the first electrode sheet, the tabs and each bending segment are correspondingly arranged, and in the second electrode sheet, the tabs and m bending segments are correspondingly connected, where 0.5n ≤ m < n. By setting a greater number of tabs on each electrode sheet to reduce the size between adjacent tabs, the electrode sheet resistance is reduced, which helps to make the current distribution in the electrode sheet more uniform, reduce the risk of lithium plating, and improve the reliability of the battery cell. Furthermore, by adjusting the number of tabs in the second electrode sheet, the number of tabs is reduced while reducing the size of adjacent tabs, thereby improving the utilization rate of the internal space of the housing and increasing the energy density of the battery cell.

[0058] The technical solutions described in the embodiments of this application are applicable to battery devices and electrical devices that use battery devices.

[0059] Electrical devices can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical devices.

[0060] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0061] The battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and this application embodiment is not limited to this. The battery cell can be cylindrical, flat, cuboid, or other shapes, and this application embodiment is not limited to this either.

[0062] The battery device mentioned in the embodiments of this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery device mentioned in this application may include a battery module or a battery pack. A battery pack generally includes a housing for encapsulating one or more battery cells. The housing can prevent liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0063] A battery cell includes electrode components and an electrolyte. The electrode components include a positive electrode, a negative electrode, and a separator. The battery cell primarily functions by the movement of metal ions between the positive and negative electrode components. The positive electrode includes a positive current collector and a positive active material layer, the latter coated on the surface of the current collector. The current collector includes a current-collecting section and a welding section for connecting the positive electrode tab. The current-collecting section is coated with the positive active material layer, while the positive electrode tab is not coated. Taking a lithium-ion battery as an example, the material of the positive current collector can be aluminum, and the positive active material layer includes positive active material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode includes a negative current collector and a negative active material layer, the latter coated on the surface of the current collector. The current-collecting section includes a current-collecting section and a welding section for connecting the negative electrode tab. The current-collecting section is coated with the negative active material layer, while the negative electrode tab is not coated. The negative electrode current collector can be made of copper, and the negative electrode active material layer includes the negative electrode active material, which can be carbon or silicon, etc. The separator can be made of PP (polypropylene) or PE (polyethylene), etc.

[0064] It should be understood that the technical solutions described in the embodiments of this application are not limited to the battery devices and electrical equipment described above, but can also be applied to all battery devices including housings and electrical equipment using battery devices. However, for the sake of brevity, the following embodiments are all illustrated using electric vehicles as examples.

[0065] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle 1 provided in some embodiments of this application. Vehicle 1 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle, or a range-extended electric vehicle, etc. A battery device 2 is installed inside vehicle 1, and the battery device 2 can be located at the bottom, front, or rear of vehicle 1. The battery device 2 can be used to power vehicle 1; for example, the battery device 2 can serve as the operating power source for vehicle 1. Vehicle 1 may also include a controller 102 and a motor 101. The controller 102 is used to control the battery to supply power to the motor 101, for example, to meet the power needs of vehicle 1 during starting, navigation, and driving.

[0066] In some embodiments of this application, the battery device 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0067] Figure 2 A schematic diagram of the structure of a battery device according to an embodiment of this application is shown.

[0068] The battery device 2 mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells 3, which are connected in series, parallel, or mixed connections via a busbar.

[0069] In some embodiments, the battery cell assembly is typically formed by arranging a plurality of battery cells 3.

[0070] As an example, the battery cell assembly can be a battery module 201, which is formed by arranging and fixing multiple battery cells 3 to form an independent module. As an example, the battery module 201 can be formed by binding multiple battery cells 3 together with cable ties.

[0071] In some embodiments, the battery device may be a battery pack, which includes a housing 202 and one or more battery cell assemblies housed in the housing 202.

[0072] As an example, the battery cell assembly can be a battery module 201, which can be housed in the housing by fixing the battery module 201 in the housing.

[0073] As an example, the battery cell assembly can also be housed in the housing 202 by directly fixing multiple battery cells 3 to the housing 202.

[0074] As an example, the housing 202 may include a first housing 2021 and a second housing 2022. The first housing 2021 and the second housing 2022 are fastened together, forming a closed space inside the housing 202 to house the battery cell assembly. Here, "closed" refers to covering or closing, which can be sealed or unsealed. The first housing 2021 may be a top cover or a bottom plate.

[0075] As an example, the housing 202 may 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 the interior of the housing 202 forms an enclosed space to accommodate the battery cell assembly.

[0076] In some embodiments, the housing 202 may be part of the vehicle's chassis structure. For example, a portion of the housing 202 may be at least a portion of the vehicle's floor, or a portion of the housing 202 may be at least a portion of the vehicle's crossbeams and longitudinal beams.

[0077] Figure 3 A schematic diagram of the structure of a battery module 201 according to an embodiment of this application is shown.

[0078] In some embodiments, such as Figure 2 and Figure 3As shown, there are multiple battery cells 3. These multiple battery cells 3 are first connected in series, parallel, or in a mixed manner to form a battery module 201. The multiple battery modules 201 are then connected in series, parallel, or in a mixed manner to form a whole, which is housed in the casing 202.

[0079] Multiple battery cells 3 in the battery module 201 can be electrically connected through a busbar component to achieve parallel, series, or mixed connection of multiple battery cells 3 in the battery module 201.

[0080] Figure 4 This is an exploded view of a battery cell according to an embodiment of this application. Battery cell 3 refers to the smallest unit that makes up the battery. For example... Figure 4 The battery cell 3 includes a top cover assembly 6, a housing 4, and an electrode assembly 5.

[0081] Electrode assembly 5 is the component in the battery cell 3 where the electrochemical reaction occurs. The casing 4 may contain one or more electrode assemblies 5. Electrode assembly 5 is mainly formed by winding or stacking electrode sheets, which are divided into positive and negative electrode sheets, and usually a separator is provided between the positive and negative electrode sheets. The portions of the positive and negative electrode sheets containing active material constitute the electrode body, while the portions of the positive and negative electrode sheets without active material each constitute a tab 511. The positive and negative tabs can be located together at one end of the electrode body or separately at both ends of the electrode body. During the charging and discharging process of the battery cell 3, the positive and negative active materials react with the electrolyte, and the tabs 511 connect to the electrode terminals to form a current loop.

[0082] The electrode assembly 5 can be a wound structure, a stacked structure, or a hybrid structure of wound and stacked.

[0083] In some embodiments, the electrode assembly 5 is a wound structure. The positive electrode and the negative electrode are wound into a wound structure.

[0084] In some embodiments, the electrode assembly 5 may be cylindrical, flat, or polygonal in shape.

[0085] In some embodiments, the electrode assembly 5 is provided with tabs that can conduct current from the electrode assembly. The tabs include a positive tab and a negative tab.

[0086] The battery cell 3 may include a housing. The housing 4 is an assembly used to cooperate with the top cover assembly 6 to form the internal environment of the battery cell 3, wherein the formed internal environment can accommodate the electrode assembly 5, electrolyte (not shown in the figure), and other components. The housing 4 can be a steel housing, an aluminum housing, a plastic housing (such as polypropylene), a composite metal housing (such as a copper-aluminum composite housing), or an aluminum-plastic film, etc. In some embodiments, the housing 4 can be a sealed structure or a non-sealed structure. As an example, when the housing 4 is a non-sealed structure, the housing 4 serves to protect the electrode assembly 5, and a sealing bag is also included between the housing 4 and the electrode assembly 5. The sealing bag is used to encapsulate the electrode assembly and electrolyte. Specifically, the sealing bag can be a bag-shaped insulating component or an aluminum-plastic film. When the housing 4 is a sealed structure, it is used to encapsulate the electrode assembly 5 and electrolyte, etc.

[0087] As an example, the battery cell 3 can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic batteries, such as hexagonal prismatic batteries. This application does not have any particular limitations.

[0088] The housing 4 and the top cover assembly 6 can be independent components. One or more openings can be provided on the housing 4, and one or more top cover assemblies 6 can close the openings to form the internal environment of the battery cell 3. Alternatively, the top cover assembly 6 and the housing 4 can be integrated. Alternatively, the top cover assembly 6 and the housing 4 can form a common connection surface before other components are inserted into the housing, and the top cover assembly 6 closes the housing 4 when it is necessary to encapsulate the interior of the housing 4.

[0089] In some embodiments, the electrode terminals can be disposed on the top cover assembly 6 or on the housing 4, and the electrode terminals are electrically connected to the tabs 511. The electrode terminals can be directly connected to the tabs 511 or indirectly connected to the tabs 511 through an adapter mechanism.

[0090] Please see Figure 5 , Figure 5 This is a schematic diagram of the structure of an electrode assembly for a battery cell provided in one embodiment of this application.

[0091] Firstly, such as Figure 4 and Figure 5As shown, this application provides a battery cell 3, which includes a housing 4 and an electrode assembly 5. The electrode assembly 5 is housed within the housing 4 and includes two wound electrode plates 51. Each electrode plate 51 includes a tab 511 and n stacked and sequentially connected bending segments 512, where n ≥ 2. The two electrode plates 51 are a first electrode plate 52 and a second electrode plate 53, respectively. In the first electrode plate 52, the tab 511 and each bending segment 512 are connected in a one-to-one correspondence. In the second electrode plate 53, the tab 511 and m bending segments 512 are connected in a one-to-one correspondence, where 0.5n ≤ m < n.

[0092] In the technical solution of this application embodiment, the battery cell 3 includes a housing 4 and an electrode assembly 5 housed within the housing 4. The electrode assembly 5 is formed by winding two electrode sheets 51, which are respectively a first electrode sheet 52 and a second electrode sheet 53. Each electrode sheet 51 includes tabs 511 and n bent segments 512 stacked and connected in sequence, where n ≥ 2. In the first electrode sheet 52, the tabs 511 and each bent segment 512 are arranged in a one-to-one correspondence. In the second electrode sheet 53, the tabs 511 and m bent segments 512 are connected in a one-to-one correspondence, where 0.5n ≤ m < n. By setting more tabs 511 on each electrode sheet 51 to reduce the size between adjacent tabs 511, the resistance of the electrode sheet 51 is reduced, which helps to make the current distribution in the electrode sheet 51 uniform, reduce the risk of lithium plating, and improve the reliability of the battery cell 3. Furthermore, by adjusting the number of tabs 511 in the second electrode sheet 53, the number of tabs 511 is reduced while reducing the size of adjacent tabs 511, thereby improving the utilization rate of the internal space of the housing 4 and increasing the energy density of the battery cell 3.

[0093] The electrode assembly 5 consists of two electrode pieces 51 wound into a flat shape, with a spacer 54 disposed between the two electrode pieces 51 to insulate adjacent electrode pieces 51. The two electrode pieces 51 are respectively a first electrode piece 52 and a second electrode piece 53. The first electrode piece 52 and the second electrode piece 53 have opposite polarities. The first electrode piece 52 is either a positive electrode piece or a negative electrode piece, and the second electrode piece 53 is either a positive electrode piece or a negative electrode piece.

[0094] The electrode 51 includes an interconnected tab 511 and a bent section 512, wherein the tab 511 is welded to the bent section 512, or the tab 511 and the bent section 512 are die-cut from the same foil.

[0095] At least two bent segments 512 are stacked and connected sequentially along the thickness direction of the electrode assembly 5. Specifically, the electrode assembly 5 includes at least one ring, each ring surrounding the center of the electrode assembly 5. The ring is formed by two adjacent bent segments 512. It should be noted that the ring is not a completely closed pattern. For example, the electrode sheet 51 may include 2, 3, 5, 10, 30, etc.

[0096] In related technologies, the tab 511 is connected to one of the adjacent bending sections 512. The distance between adjacent tabs 511 is large, and the resistance of the electrode 51 is large. During fast charging, the uniform distribution of current density is easily deteriorated, which can lead to purple spots or lithium plating.

[0097] In this embodiment of the application, the tabs 511 and each bending segment 512 in the first electrode 52 are connected in a one-to-one correspondence. Thus, the number of tabs 511 and the number of bending segments 512 in the first electrode 52 are the same, and each bending segment 512 is connected to a tab 511. In this way, by increasing the number of tabs 511, the phenomenon of uneven current distribution can be effectively reduced.

[0098] Meanwhile, considering that an excessive number of tabs 511 would lead to excessive space occupation within the casing 4 and a decrease in the energy density of the battery cell 3, the m bending segments 512 in the second electrode 53 are connected one-to-one with the tabs 511, where 0.5n ≤ m < n. This effectively reduces uneven current distribution by increasing the number of tabs 511 while simultaneously improving the energy density of the battery cell 3 by reasonably reducing the number of tabs 511. For example, m can be 0.5n, 0.6n, 0.75n, or 0.8n, etc.

[0099] In some embodiments, such as Figure 4 and Figure 5 As shown, the first electrode 52 is the negative electrode, and the second electrode 53 is the positive electrode.

[0100] In these embodiments, during charging, lithium ions are embedded in the negative electrode. Therefore, more tabs 511 are provided on the negative electrode, reducing the size of the negative electrode between adjacent tabs 511, reducing the resistance of the negative electrode, reducing the difficulty of lithium embedding in the negative electrode, and improving the charging rate of the battery cell 3.

[0101] For example, the current collector of the positive electrode is aluminum foil, and the current collector of the negative electrode is copper foil. Generally speaking, aluminum foil is thicker. Therefore, appropriately reducing the number of tabs 511 of the positive electrode can more effectively improve the energy density of the battery cell 3.

[0102] Please see Figure 6 , Figure 7 and Figure 8 , Figure 6 This is a schematic diagram of the structure of the first electrode of a battery cell according to an embodiment of this application; Figure 7 This is a schematic diagram of the first part of the structure of the second electrode of a battery cell according to an embodiment of this application; Figure 8 This is a schematic diagram of the second part of the structure of the second electrode of a battery cell provided in an embodiment of this application.

[0103] In some embodiments, such as Figures 5 to 8As shown, the second electrode 53 includes a first part 531 and a second part 532 that are connected to each other. The first part 531 includes n1 bending segments 512, and the second part 532 includes n2 bending segments 512, where n1≥2 and n2≥2. In the first part 531, the electrode tab 511 is connected to each bending segment 512 in a one-to-one correspondence, and in the second part 532, the electrode tab 511 is connected to ceil(n2 / 2) bending segments 512 in a one-to-one correspondence.

[0104] In these embodiments, the second electrode 53 includes two parts: a first part 531 and a second part 532. The tabs 511 are regularly arranged in the first part 531 to reduce the overall processing difficulty of the second electrode 53.

[0105] like Figure 6 As shown, in the first electrode plate 52, the tab 511 and the bent section 512 are connected in a one-to-one correspondence; as Figure 7 and Figure 8 As shown, the second electrode 53 includes a first part 531 and a second part 532. The first part 531 includes n1 bending segments 512, and the second part 532 includes n2 bending segments 512, where n1 + n2 = n.

[0106] For example, the first part 531 includes 2, 3, 4 or 5 bends 512; the second part 532 includes 2, 3, 4 or 5 bends 512.

[0107] ceil(n2 / 2) means rounding up the value of (n2 / 2). For example, if n2 / 2 = 1.5, then ceil(n2 / 2) = 2; if n2 / 2 = 2.5, then ceil(n2 / 2) = 3.

[0108] In the first part 531, the tab 511 and each bending segment 512 are connected one-to-one, which can reduce the processing difficulty of the electrode 51. In the second part 532, the tab 511 and each of the ceil(n2 / 2) bending segments 512 are connected one-to-one.

[0109] For example, in the second part 532, a bend segment 512 is provided between adjacent tabs 511 so that the tabs 511 are evenly spaced in the second part 532.

[0110] In some embodiments, such as Figures 5 to 8 As shown, the first part 531 includes n1 bends 512, n1 = floor(n / 2); the second part 532 includes n2 bends 512, n2 = ceil(n / 2).

[0111] In these embodiments, the first part 531 is provided with floor(n / 2) bending segments 512; the second part 532 is provided with ceil(n / 2) bending segments 512, so as to reduce the processing difficulty of the electrode 51 and uniformly distribute the current in the second part 532.

[0112] When the second electrode 53 includes n bending segments 512, and n is an even number, n1 and n2 equally divide the n bending segments 512, and both n1 and n2 are n / 2.

[0113] When the second electrode 53 includes n bending segments 512, and n is an odd number, n1 = floor(n / 2) and n2 = ceil(n / 2).

[0114] floor(n / 2) represents the floor function rounding down the value of (n / 2). For example, if n / 2 = 1.5, then floor(n / 2) = 1; if n / 2 = 2.5, then floor(n / 2) = 2.

[0115] ceil(n / 2) means rounding up the value of (n / 2). For example, if n / 2 = 1.5, then ceil(n / 2) = 2; if n / 2 = 2.5, then ceil(n / 2) = 3.

[0116] By using the ceil function and the floor function to set more bending segments 512 in the second part 532, the number of tabs 511 in the second part 532 is increased, and the current distribution in the second part 532 is made more uniform.

[0117] For example, if the second electrode 53 includes 13 bending segments 512, then n1 = floor(n / 2) = 6, n2 = ceil(n / 2) = 7; if the second electrode 53 includes 14 bending segments 512, then n1 = floor(n / 2) = 7, n2 = ceil(n / 2) = 7.

[0118] In some embodiments, such as Figures 5 to 8 As shown, the first part 531 is closer to the center of the electrode assembly 5 than the second part 532.

[0119] In these embodiments, the second portion 532 is located on the outside of the electrode assembly 5, and the first portion 531 is located on the inside of the electrode assembly 5. Relatively speaking, the outer tab 511 is relatively long, and reducing the number of outer tabs 511 helps to reduce the material cost of the electrode sheet 51.

[0120] The first part 531 is closer to the center of the electrode assembly 5 than the second part 532, or in other words, the second part 532 is wrapped around the outside of the first part 531.

[0121] Considering that after the electrode assembly 5 is wound, the tabs 511 need to be gathered and bent to be welded to the adapter mechanism 7, the outer tabs 511 are longer than the inner tabs 511 to facilitate bending of the outer tabs 511 toward the center, thereby reducing the welding difficulty between the tabs 511 and the adapter mechanism 7. Therefore, in this embodiment, the second part 532 is provided with fewer tabs 511 to reduce the material cost of the electrode sheet 51.

[0122] Please see Figure 9 , Figure 9 This is a schematic diagram of the structure of the electrode assembly of a battery cell provided in an embodiment of this application.

[0123] In some embodiments, such as Figures 7 to 9 As shown, the second part 532 is closer to the center of the electrode assembly 5 than the first part 531.

[0124] In these embodiments, the first part 531 is located on the outside of the electrode assembly 5, and the second part 532 is located on the inside of the electrode assembly 5. Relatively speaking, the extension dimension of the outer bending section 512 is longer, so more tabs 511 are provided on the outside to reduce the spacing between adjacent tabs 511, reduce the internal resistance of the electrode 51 between adjacent tabs 511, help to make the current distribution in the electrode 51 uniform, reduce the risk of lithium plating, and improve the reliability of the battery cell 3.

[0125] The second part 532 is closer to the center of the electrode assembly 5 than the first part 531, or in other words, the first part 531 is wrapped around the outside of the second part 532.

[0126] As the electrode sheet 51 is wound, the thickness of the electrode assembly 5 increases, and the dimension of the outer bending section 512 of the electrode assembly 5 in its extension direction will be greater than the dimension of the inner bending section 512 of the electrode assembly 5 in its extension direction.

[0127] Therefore, by placing a greater number of tabs 511 on the first part 531, that is, on the outside of the electrode assembly 5, the internal resistance of the electrode sheet 51 between adjacent tabs 511 on the outside of the electrode assembly 5 can be reduced, so as to effectively uniform the current density of the outer layer of the electrode assembly 5 and reduce the risk of lithium plating and purple spots.

[0128] In some embodiments, such as Figures 5 to 8 As shown, in the second part 532, a bent section 512 is provided between adjacent tabs 511.

[0129] In these embodiments, a bend 512 is provided between adjacent tabs 511. The uniform arrangement of tabs 511 helps to achieve a uniform current distribution on the electrode 51 and reduces the risk of lithium plating on the electrode 51.

[0130] It should be noted that, since the actual extension dimensions of each bending segment 512 are different, the extension dimension of the inner bending segment 512 is smaller and the extension dimension of the outer bending segment 512 is larger, the spacing between adjacent tabs 511 is not exactly the same.

[0131] Optionally, each tab 511 is centered on the bend section 512 so that each tab 511 is relatively evenly distributed.

[0132] Please see Figure 10 , Figure 10 This is a partial structural schematic diagram of a battery cell provided in one embodiment of this application.

[0133] In some embodiments, such as Figure 4 , Figure 5 and Figure 10 As shown, the battery cell 3 also includes an adapter mechanism 7, which includes a welding area 71. The tab 511 is welded to the welding area 71 and the adapter mechanism 7. The area of ​​the welding area 71 is S0, and the surface area of ​​the tab 511 on one side in its thickness direction is S1, which satisfies 0.1≤S0 / S1≤1.

[0134] In these embodiments, the tab 511 is connected to the welding area 71 of the adapter 7 and the adapter 7. When the area of ​​the welding area 71 and the surface area of ​​the tab 511 on its thickness side meet the above conditions, the problem of insufficient overcurrent area between the tab 511 and the adapter 7, which affects the fast charging capability of the battery cell 3, is improved.

[0135] After several tabs 511 are gathered together, one side surface of the outermost tab 511 is welded to the welding area 71 of the adapter 7 so that the electrode assembly 5 and the adapter 7 can conduct electricity. The welding method can be laser welding or microwave welding, etc.

[0136] For example, the value of S0 / S1 can be 0.1, 0.2, 0.5, 0.9, 1.0, etc.

[0137] In some embodiments, such as Figure 5 and Figure 10 As shown, the welding area 71 has a dimension L1 in the first direction X and a dimension L2 in the second direction Y, which satisfy 6≤L1 / L2≤7. The first direction X and the second direction Y intersect, and the second direction Y is the extension direction of the tab 511.

[0138] In these embodiments, when the dimensions of the welding area 71 in the first direction X and the second direction Y satisfy the above conditions, the problem of insufficient overcurrent area between the tab 511 and the adapter 7, which affects the fast charging capability of the battery cell 3, is improved.

[0139] For example, L1 / L2 can be 6, 6.5, or 7, etc.

[0140] The second direction Y is the extension direction of the tab 511, which means that the second direction Y is the direction in which the tab 511 extends out of the bent section 512.

[0141] The battery cell 3 provided by the present invention will be described below through specific embodiments.

[0142] Example: The electrode assembly 5 includes two wound electrode sheets 51. Each electrode sheet 51 includes tabs 511 and 58 stacked and sequentially connected bent segments 512. The two electrode sheets 51 are a first electrode sheet 52 and a second electrode sheet 53, respectively. The first electrode sheet 52 is a negative electrode sheet, and the second electrode sheet 53 is a positive electrode sheet. In the first electrode sheet 52, the 58 tabs 511 and each bent segment 512 are connected in a one-to-one correspondence. The second electrode sheet 53 includes a first part 531 and a second part 532 that are connected to each other. The first part 531 includes 29 bent segments 512, and the second part 532 includes 15 bent segments 512. In the first part 531, the tabs 511 and each bent segment 512 are connected in a one-to-one correspondence. In the second part 532, adjacent tabs 511 are spaced apart by one bent segment. The first part 531 is closer to the center of the electrode assembly 5 than the second part 532.

[0143] Comparative Example 1: Each electrode 51 has 58 bending segments 512 and 29 tabs 511 connected together, with a bending segment 512 between two adjacent tabs 511. Other conditions are the same as in the embodiment.

[0144] Comparative Example 2: Each electrode 51 has 58 bending segments 512 and 58 tabs 511 connected in a one-to-one correspondence, with other conditions being the same as in the embodiment.

[0145] Comparative Example 3: The first electrode 52 and the second electrode 53 include a first part 531 and a second part 532 that are connected to each other. The first part 531 includes 29 bending segments 512, and the second part 532 includes 15 bending segments 512. In the first part 531, the tabs 511 are connected to each bending segment 512 in a one-to-one correspondence. In the second part 532, adjacent tabs 511 are separated by a bending segment. The first part 531 is closer to the center of the electrode assembly 5 than the second part 532. Other conditions are the same as in the embodiment.

[0146] Figure 11 The horizontal axis represents the position of the electrode plate 51 gradually moving away from the core after the electrode plate 51 of the electrode assembly 5 is unfolded, from left to right, to show the effect of different electrode tab 511 settings on the current density distribution of the electrode assembly 5.

[0147] Depend on Figure 11It can be seen that the current density distribution of the scheme in the embodiment and the scheme in Comparative Example 2 is more uniform. The simulation results show that the non-uniformity of the current density distribution in the outer ring of the electrode assembly is 90% smaller than that of the scheme in Comparative Example 2. Therefore, the scheme in the embodiment can significantly improve the current density distribution of the second electrode 53.

[0148] Figure 12 The effect of different tab 511 settings on the impedance of electrode assembly 5 is shown on the horizontal axis, which represents SOC (State of Charge) and the vertical axis, which represents DCR (Direct Current Resistance).

[0149] Depend on Figure 12 It can be seen that the impedance of the electrode assembly 5 in the embodiment is 0.5 mohm smaller than that in Comparative Example 2 and 0.1 mohm smaller than that in Comparative Example 3. Due to the reduced internal resistance, the temperature rise of the electrode assembly 5 is 1-2℃ lower. This can further reduce the temperature difference between the inner and outer sides of the electrode assembly 5, ensure the consistency of the internal and external performance of the electrode assembly 5, and reduce the risk of lithium plating on the outer side of the electrode assembly 5 at the end of charging.

[0150] Figure 13 and Figure 14 This is a graph showing the lithium plating potential data for a hard-shell three-electrode configuration. Figure 13 and Figure 14 As can be seen from the study, when the battery cell 3 was fully charged at a 2C rate using a hard-shell three-electrode method, the lithium plating SOC of the embodiment was 30% higher than that of the comparative embodiment 3 at the same test position, and the lithium plating potential was 20mV-30mV higher, thus enhancing its charging capability.

[0151] Secondly, this application provides a battery device including the battery cell described in the first aspect embodiment above.

[0152] Thirdly, this application provides an electrical device including the battery device described in the third aspect embodiment above.

[0153] In some embodiments, such as Figures 1 to 14As shown, this application provides a battery cell 3, which includes a housing 4 and an electrode assembly 5. The electrode assembly 5 is housed within the housing 4 and includes two wound electrode plates 51. Each electrode plate 51 includes tabs 511 and n stacked and sequentially connected bent segments 512. The two electrode plates 51 are a first electrode plate 52 and a second electrode plate 53, respectively. The first electrode plate 52 is a negative electrode plate, and the second electrode plate 53 is a positive electrode plate. The tabs 511 and n bent segments 512 of the first electrode plate 52 are... The bent segments 512 are connected one-to-one. In the second pole piece 53, the tabs 511 and m bent segments 512 are connected one-to-one, where 0.5n ≤ m < n. The second pole piece 53 includes a first part 531 and a second part 532 that are interconnected. The first part 531 includes n1 bent segments 512, and the second part 532 includes n2 bent segments 512, where n1 = floor(n / 2), n2 = ceil(n / 2), n1 ≥ 2, and n2 ≥ 2. In the first part 531, the tabs 511 and each bending segment 512 are connected one-to-one. In the second part 532, the tabs 511 and ceil(n2 / 2) bending segments 512 are connected one-to-one. The first part 531 is closer to the center of the electrode assembly 5 than the second part 532. In the second part 532, a bending segment 512 is provided between adjacent tabs 511. The battery cell 3 also includes a connecting mechanism 7, which includes a welding area 71. The tabs 511 are welded to the connecting mechanism 7 in the welding area 71. The area S0 of the welding area 71 and the surface area S1 of the tab 511 on one side in its thickness direction satisfy 0.1≤S0 / S1≤1. The dimension L1 of the welding area 71 in the first direction X and the dimension L2 of the welding area 71 in the second direction Y satisfy 6≤L1 / L2≤7. The first direction X and the second direction Y intersect. The second direction Y is the extension direction of the tab 511.

[0154] In these embodiments, the battery cell 3 includes a housing 4 and an electrode assembly 5 housed within the housing 4. The electrode assembly 5 is formed by winding two electrode sheets 51, which are respectively a first electrode sheet 52 and a second electrode sheet 53. Each electrode sheet 51 includes tabs 511 and n bent segments 512 stacked and connected in sequence, where n ≥ 2. In the first electrode sheet 52, the tabs 511 and each bent segment 512 are arranged in a one-to-one correspondence. In the second electrode sheet 53, the tabs 511 and m bent segments 512 are connected in a one-to-one correspondence, where 0.5n ≤ m < n. By setting more tabs 511 on each electrode sheet 51 to reduce the size between adjacent tabs 511, the resistance of the electrode sheet 51 is reduced, which helps to make the current distribution in the electrode sheet 51 uniform, reduce the risk of lithium plating, and improve the reliability of the battery cell 3. Furthermore, by adjusting the number of tabs 511 in the second electrode sheet 53, the number of tabs 511 is reduced while reducing the size of adjacent tabs 511, thereby improving the utilization rate of the internal space of the housing 4 and increasing the energy density of the battery cell 3.

[0155] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized by, The battery monomer comprises: a shell; an electrode assembly accommodated in the shell, the electrode assembly comprising two wound electrode tabs, the electrode tab comprising an ear and n folded segments stacked and connected in sequence, n≥2, wherein the two electrode tabs are a first electrode tab and a second electrode tab, the ear and each folded segment in the first electrode tab are one-to-one connected, and the ear and m folded segments in the second electrode tab are one-to-one connected, 0.5n≤m<n.

2. The battery cell of claim 1, wherein, The first electrode tab is a negative electrode tab, and the second electrode tab is a positive electrode tab.

3. The battery cell of claim 1, wherein, The second electrode tab comprises a first part and a second part connected to each other, the first part comprises n1 folded segments, and the second part comprises n2 folded segments, n1≥2, n2≥2, in the first part, the ear and each folded segment are one-to-one connected, and in the second part, the ear and ceil(n2 / 2) folded segments are one-to-one connected.

4. The battery cell of claim 3, wherein, The first part comprises n1 folded segments, n1=floor(n / 2); the second part comprises n2 folded segments, n2=ceil(n / 2).

5. The battery cell of claim 4, wherein, The first part is closer to the center of the electrode assembly than the second part.

6. The battery cell of claim 4, wherein, The second part is closer to the center of the electrode assembly than the first part.

7. The battery cell of claim 3, wherein, In the second part, one folded segment is arranged between adjacent ears.

8. The battery cell of claim 1, wherein, The battery monomer further comprises a switching mechanism, the switching mechanism comprising a welding area, the ear being welded and connected to the switching mechanism at the welding area, The area of the welding area S0, the surface area of the ear on one side of its thickness direction S1 satisfy 0.1≤S0 / S1≤1.

9. The battery cell of claim 8, wherein, The size of the welding area in the first direction L1, the size of the welding area in the second direction L2 satisfy 6≤L1 / L2≤7, the first direction and the second direction intersect, and the second direction is the extension direction of the ear.

10. A battery device characterized by comprising: The battery device comprises the battery monomer of any one of claims 1-9.

11. An electrical device, characterized by The battery device comprises the battery monomer of claim 10.

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