Battery monomer, battery and electric equipment

Abstract

The embodiment of the utility model provides a battery monomer, a battery and electric equipment. The battery monomer comprises a shell, a top cover and an electrode assembly, the housing has an accommodation space and an opening. And the top cover hermetically covers the opening. The electrode assembly is arranged in the accommodating space. Wherein the partial area, close to the bottom, of the inner side wall of the shell is thinned to form a thinned area, and the lowest point of the thinned area is not higher than the lowest point of the electrode assembly. According to the battery monomer provided by the embodiment of the invention, the partial region, close to the bottom, of the inner side wall of the shell is thinned to form the thinned region, and when the electrode assembly circularly expands, the thinned region can avoid the lower region of the electrode assembly, so that a larger expansion space is provided for the lower region of the electrode assembly, and the expansion efficiency of the battery monomer is improved. The problem of lithium precipitation caused by stress concentration between the lower area of the electrode assembly and the shell due to expansion can be improved to a certain extent, so that the performance of the battery monomer is improved, and the service life of the battery monomer is prolonged.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery cell, a battery, and an electrical device. Background Art

[0002] This section is intended to provide a background or context for the embodiments of the present application. No description herein is admitted to be prior art by virtue of its inclusion in this section.

[0003] In new energy vehicles equipped with batteries, the batteries can be used to provide all or part of the power. In the battery production process, the bare cell is placed in a housing and the top cover is closed to obtain the encased cell. In related technologies, bare cells expand during cycling, especially at the bottom of the cell, where the expansion force is greater. This can lead to stress concentration at the bottom of the cell, resulting in problems such as lithium deposition. Utility Model Content

[0004] In view of this, the embodiments of the present application hope to provide a battery cell, a battery, and an electrical device that can improve the problem of lithium plating caused by stress concentration.

[0005] To achieve the above objectives, a first aspect of an embodiment of the present application provides a battery cell, comprising:

[0006] a housing having a receiving space and an opening;

[0007] A top cover and a sealing cover are provided at the opening;

[0008] an electrode assembly, disposed in the accommodation space;

[0009] Part of the inner side wall of the shell near the bottom is thinned to form a thinned area, and the lowest point of the thinned area is not higher than the lowest point of the electrode assembly.

[0010] The battery cell provided in the embodiment of the present application includes a shell, a top cover and an electrode assembly. The thinning area is formed by thinning a part of the inner wall of the shell near the bottom, and the lowest point of the thinning area is set to be no higher than the lowest point of the electrode assembly. Therefore, when the electrode assembly expands during a cycle, the thinning area can avoid the lower area of the electrode assembly, providing the lower area of the electrode assembly with a larger expansion space. To a certain extent, it can improve the problem of lithium plating caused by stress concentration between the lower area of the electrode assembly and the shell due to expansion, thereby improving the performance and service life of the battery cell.

[0011] In some embodiments, the battery cell further includes a buffer member attached to an outer side wall of the housing, and the lowest point of the thinned area is no higher than the lowest point of the buffer member.

[0012] In this embodiment, by providing a buffer, a buffering effect can be played on the battery cell, thereby improving the probability of the battery cell being damaged. At the same time, when the electrode assembly expands during a cycle, the thinning area can avoid the lower area of the electrode assembly, providing the lower area of the electrode assembly with a larger expansion space. Setting the lowest point of the thinning area to be no higher than the lowest point of the buffer can further avoid the problem of stress concentration caused by the thinning area squeezing the buffer, thereby further improving the problem of lithium deposition caused by stress concentration between the lower area of the electrode assembly and the outer shell due to expansion, thereby improving the performance and service life of the battery cell.

[0013] In some embodiments, the housing includes multiple surfaces, the multiple surfaces including a first surface, the first surface being the surface with the largest area among the multiple surfaces; the buffer member is attached to the first surface, the buffer member includes two first connecting segments spaced apart in a height direction of the battery cell and two second connecting segments spaced apart in the first direction, the two first connecting segments and the two second connecting segments are connected end to end, and the first direction intersects with the height direction of the battery cell;

[0014] Wherein, when projected onto the plane where the first surface is located, the projection of the first connecting segment away from the opening is located within the projection range of the thinning area.

[0015] That is to say, the inner side walls of the shell corresponding to the first connecting section away from the opening are thinned to form a thinned area. In other words, the inner side walls of the shell in the area where the buffer part is attached are provided with a thinned area to avoid the electrode assembly and the buffer part, thereby improving the problem that the lower area of the electrode assembly expands due to expansion, and then squeezes the buffer part to generate stress concentration and cause lithium deposition, thereby improving the performance and service life of the battery cell.

[0016] In some embodiments, the distance between the lowest point of the thinned area and the bottom wall of the housing is L1, where 0≤L1≤10 mm.

[0017] It can effectively improve the problem of lithium deposition caused by stress concentration between the lower area of the electrode assembly and the shell due to expansion, while ensuring that the shell has sufficient strength.

[0018] In some embodiments, the size of the housing in the height direction of the battery cell is L, and the size of the thinned area in the height direction of the battery cell is L2, wherein:

[0019] The shell can have sufficient structural strength, and the thinned area can effectively avoid the electrode assembly and the buffer component.

[0020] In some embodiments, the wall thickness of the thinned area is H1, and the wall thickness of other areas of the shell except the thinned area is H, wherein,

[0021] The thinned area can have sufficient structure, that is, the shell has sufficient structural strength, and the thinned area can effectively avoid the electrode assembly and the buffer component.

[0022] In some embodiments, the wall thickness of the thinned area is H1, and the wall thickness of other areas of the shell except the thinned area is H, wherein,

[0023] The thinned area can further have sufficient structure, that is, the shell has sufficient structural strength, and the thinned area can further effectively avoid the electrode assembly and the buffer.

[0024] In some embodiments, the wall thickness of the thinned area is H1, wherein 0.25 mm ≤ H1 ≤ 1.45 mm.

[0025] The thinned area can have sufficient structure, that is, the shell has sufficient structural strength, and the thinned area can effectively avoid the electrode assembly and the buffer component.

[0026] In some embodiments, the wall thickness of the thinned area is H1, and the wall thickness of other areas of the shell except the thinned area is H, wherein 0.05 mm ≤ H - H1 ≤ 0.7 mm.

[0027] The thinned area can have sufficient structure, that is, the shell has sufficient structural strength, and the thinned area can effectively avoid the electrode assembly and the buffer component.

[0028] A second aspect of an embodiment of the present application provides a battery comprising at least one of the battery cells described above.

[0029] The battery cell of the battery provided in the embodiment of the present application includes a shell, a top cover and an electrode assembly. The thinning area is formed by thinning a part of the inner wall of the shell near the bottom, and the lowest point of the thinning area is set to be no higher than the lowest point of the electrode assembly. Therefore, when the electrode assembly expands during a cycle, the thinning area can avoid the bottom area of the electrode assembly, which can improve to a certain extent the problem of lithium plating caused by stress concentration between the bottom area of the electrode assembly and the shell due to expansion, thereby improving the performance and service life of the battery cell.

[0030] A third aspect of an embodiment of the present application provides an electrical device, comprising the battery described above, wherein the battery is used to provide electrical energy.

[0031] The battery for the electrical equipment provided in the embodiment of the present application comprises a battery cell including a shell, a top cover and an electrode assembly. A thinned area is formed by thinning a portion of the inner wall of the shell near the bottom, and the lowest point of the thinned area is set to be no higher than the lowest point of the electrode assembly. Thus, when the electrode assembly expands during a cycle, the thinned area can avoid the bottom area of the electrode assembly, which can to a certain extent improve the problem of lithium plating caused by stress concentration between the bottom area of the electrode assembly and the shell due to expansion, thereby improving the performance and service life of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic structural diagram of a vehicle provided in one embodiment of the present application;

[0033] Figure 2 A schematic exploded perspective view of a battery according to an embodiment of the present application;

[0034] Figure 3 A schematic structural diagram of a positive electrode sheet provided in one embodiment of the present application;

[0035] Figure 4 A cross-sectional view of an electrode assembly provided in one embodiment of the present application;

[0036] Figure 5 A schematic structural diagram of a battery cell provided in one embodiment of the present application;

[0037] Figure 6 for Figure 5 a cross-sectional view of the electrode assembly shown;

[0038] Figure 7 for Figure 6 Enlarged view of point A in the middle;

[0039] Figure 8 A cross-sectional view of a housing provided in accordance with an embodiment of the present application.

[0040] Description of Reference Numerals

[0041] 10. Battery cell; 11. Casing; 11a. Accommodation space; 11b. Opening; 11c. Thinning area; 11d. First surface; 12. Top cover; 13. Buffer; 131. First connecting section; 132. Second connecting section; 14. Electrode assembly; 14a. Thinning area; 141. Positive electrode sheet; 1411. Positive current collector; 1412. Positive active material; 142. Negative electrode sheet; 1421. Negative current collector; 1422. Negative active material; 143. Separator; 20. Battery case; 21. First case body; 22. Second case body; 100. Battery; 200. Controller; 300. Motor; 1000. Vehicle. DETAILED DESCRIPTION

[0042] It should be noted that, unless there is a conflict, the embodiments and technical features in the embodiments of this application can be combined with each other, and the detailed description in the specific implementation method should be understood as an explanation of the purpose of this application and should not be regarded as an improper restriction on this application.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit this application; the terms "including" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusions.

[0044] In the description of the embodiments of this application, the technical terms "first," "second," "third," etc. are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise specifically defined.

[0045] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0046] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0047] In the description of the embodiments of the present application, the technical terms "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "circumferential", "height direction", "first direction", "second direction", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed, operated or used in a specific orientation. Therefore, they should not be understood as limitations on the embodiments of the present application.

[0048] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0049] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, the technical term "contact" should be understood in a broad sense, and can be direct contact, contact through an intermediate medium layer, contact with essentially no interaction force between the two contacting parties, or contact with interaction force between the two contacting parties.

[0050] With the development of clean energy, more and more devices are using electricity as a driving force. Consequently, power batteries, such as lithium-ion batteries, that can store large amounts of electricity and undergo multiple charge and discharge cycles are rapidly developing. These batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but are also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric vehicles, as well as in aerospace and other fields.

[0051] With the country's vigorous promotion of new energy vehicles, new energy vehicles have ushered in a golden opportunity for development. Vehicle safety and stability have always been of primary concern. Therefore, improving the safety of new energy vehicles will be one of the key factors determining their rapid adoption. Improving battery safety is a key approach to improving the safety of new energy vehicles.

[0052] The battery referred to in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may include a battery module or a battery pack. A battery generally includes a casing that encloses one or more battery cells. The casing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0053] A battery cell includes an electrode assembly and an electrolyte. The electrode assembly consists of a positive electrode sheet, a negative electrode sheet, and a separator. A battery cell primarily operates by the movement of metal ions between the positive and negative electrode sheets. The positive electrode sheet includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive electrode collector. The uncoated positive electrode collector protrudes from the coated positive electrode collector, and the uncoated positive electrode collector serves as the positive electrode tab. For lithium-ion batteries, for example, the positive electrode current collector can be made of aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. The negative electrode sheet includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative electrode collector. The uncoated negative electrode collector protrudes from the coated negative electrode collector, and the uncoated negative electrode collector serves as the negative electrode tab. The negative electrode current collector can be made of copper, and the negative electrode active material can be carbon or silicon. To ensure high current flow without melting, multiple positive electrode tabs are stacked together, and multiple negative electrode tabs are stacked together. The separator can be made of materials such as PP (polypropylene) or PE (polyethylene).

[0054] Illustratively, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is disposed on either or both of the two facing surfaces of the positive electrode current collector.

[0055] For example, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. may be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0056] Illustratively, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0057] For example, the negative electrode current collector may be a metal foil or a composite current collector. For example, the metal foil may be silver-plated aluminum, silver-plated stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium.

[0058] Illustratively, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is disposed on either or both of the two facing surfaces of the negative electrode current collector.

[0059] Illustratively, the negative electrode active material may be a negative electrode active material for a battery that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0060] The battery cell also includes an insulating film and a shell. The insulating film is coated on the outside of the electrode assembly, and the shell encapsulates the electrode assembly coated with the insulating film to form a battery cell. The insulating film can be Mylar film, and the shell can be aluminum or steel. After the electrode assembly is wound and formed, the Mylar film and shell are encapsulated through the Mylar wrapping process and the shell insertion process. The Mylar film seals and protects the electrode assembly, and the Mylar film can effectively insulate the electrode assembly and the shell from each other, preventing internal short circuits in the battery cell. The shell also plays a protective role.

[0061] Illustratively, the housing includes a top cover and an outer shell. The outer shell has an opening, and the top cover closes the opening to form a sealed space for accommodating materials such as the electrode assembly and electrolyte. The outer shell may have one or more openings. The top cover may also have one or more openings.

[0062] Illustratively, at least one electrode terminal is provided on the housing, and the electrode terminal is electrically connected to the tab of the electrode assembly. The electrode terminal can be directly connected to the tab or indirectly connected to the tab via an adapter. The electrode terminal can be provided on the top cover or the housing.

[0063] Exemplarily, an explosion-proof valve is provided on the housing to release the internal pressure of the battery cell.

[0064] The development of battery technology must take into account multiple design factors at the same time, such as energy density, discharge capacity, charge and discharge rate and other performance parameters. In addition, the safety and reliability of the battery must also be considered.

[0065] Taking lithium-ion batteries as an example, the current lithium-ion batteries have high energy density requirements, so the current collector often needs to go through a cold pressing process after coating. During cold pressing, the interface between the active material and the current collector is in order to prevent stress concentration, such as Figure 3 As shown, the transition area needs to be thinned so that after the pole piece is wound, its cross-sectional structure is as follows Figure 4As shown, this will result in a situation where the gaps at the top of the battery cell are large and the gaps at the bottom are small. During the cycling process, the electrode assembly will expand. Since the gaps at the top of the battery cell are large and the gaps at the bottom are small, the expansion force in the lower area of the electrode assembly is greater, which leads to stress concentration in the lower area of the electrode assembly, resulting in problems such as lithium deposition.

[0066] In view of this, and to address the issue of lithium deposition caused by stress concentration, an embodiment of the present application provides a battery cell comprising a housing, a top cover, and an electrode assembly. The housing has a receiving space and an opening. A top cover sealing cap is disposed at the opening. The electrode assembly is disposed within the receiving space. Part of the inner sidewall of the housing near the bottom is thinned to form a thinned region, with the lowest point of the thinned region being no higher than the lowest point of the electrode assembly.

[0067] The battery cell provided in the embodiment of the present application includes a shell, a top cover and an electrode assembly. The thinning area is formed by thinning a part of the inner wall of the shell near the bottom, and the lowest point of the thinning area is set to be no higher than the lowest point of the electrode assembly. Therefore, when the electrode assembly expands during a cycle, the thinning area can avoid the lower area of the electrode assembly, providing the lower area of the electrode assembly with a larger expansion space. To a certain extent, it can improve the problem of lithium plating caused by stress concentration between the lower area of the electrode assembly and the shell due to expansion, thereby improving the performance and service life of the battery cell.

[0068] The technical solutions described in the embodiments of this application are applicable to electric devices using batteries. The electric devices include the batteries of any embodiment of this application, and the batteries are used to provide electrical energy.

[0069] Electrical equipment can be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and electric tools, etc. Vehicles can be fuel vehicles, gas vehicles, or new energy vehicles. New energy vehicles can be pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical equipment.

[0070] It should be noted that the technical solutions described in the embodiments of the present application are not limited to the batteries and electrical equipment described above, but can also be applied to all batteries including boxes and electrical equipment using batteries. However, for the sake of simplicity, the following embodiments are described using electric vehicles as an example.

[0071] Please refer to Figure 1 , Figure 1 A schematic structural diagram of a vehicle 1000 provided for some embodiments of the present application. A controller 200, a motor 300, and a battery 100 may be provided inside the vehicle 1000, and the controller 200 is used to control the battery 100 to power the motor 300. For example, the battery 100 may be provided at the bottom, front, or rear of the vehicle 1000. The battery 100 may be used to power the vehicle 1000. For example, the battery 100 may be used as an operating power source for the vehicle 1000, for the circuit system of the vehicle 1000, for example, for the working power requirements during the start-up, navigation, and operation of the vehicle 1000. In another embodiment of the present application, the battery 100 may not only serve as an operating power source for the vehicle 1000, but may also serve as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0072] To meet varying power requirements, the battery 100 may include multiple battery cells 10. A battery cell 10 is the smallest unit that makes up a battery module or battery pack. Multiple battery cells 10 may be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a combination of series and parallel connections within the battery cells 10. Multiple battery cells 10 may be directly connected in series, in parallel, or in a hybrid configuration, and then the entire battery cell 10 is housed within a housing. Alternatively, the battery 100 may be constructed by first connecting multiple battery cells 10 in series, in parallel, or in a hybrid configuration to form a battery module. The battery 100 may also include other structures. For example, the battery 100 may include a busbar to electrically connect the multiple battery cells 10. Each battery cell 10 may be a secondary battery or a primary battery; it may also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cells 10 may be cylindrical, flat, rectangular, or have other shapes.

[0073] Figure 2 This is a perspective exploded diagram of a battery provided in an embodiment of the present application. The battery includes a battery box 20 and at least one battery cell 10 , which is disposed in an installation space of the battery box 20 .

[0074] The battery case 20 can be a simple three-dimensional structure such as a single rectangular parallelepiped, cylinder, or sphere, or a complex three-dimensional structure composed of simple three-dimensional structures such as rectangular parallelepiped, cylinder, or sphere. The battery case 20 can be made of an alloy material such as aluminum alloy or iron alloy, a polymer material such as polycarbonate or polyisocyanurate foam, or a composite material such as glass fiber and epoxy resin.

[0075] The battery case 20 is used to accommodate the battery cells 10 and can have various structures. In some embodiments, the battery case 20 can include a first case portion 21 and a second case portion 22. The first case portion 21 and the second case portion 22 cover each other and together define an installation space for accommodating the battery cells 10. The second case portion 22 can be a hollow structure with an opening 11b at one end. The first case portion 21 is a plate-like structure, and the first case portion 21 covers the opening 11b side of the second case portion 22 to form the battery case 20 with an installation space. The first case portion 21 and the second case portion 22 can also both be hollow structures with an opening 11b at one end, and the opening 11b side of the first case portion 21 covers the opening 11b side of the second case portion 22 to form the battery case 20 with an installation space. Of course, the first case portion 21 and the second case portion 22 can have various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0076] In order to improve the sealing performance after the first box body 21 and the second box body 22 are connected, a sealing member, such as a sealant, a sealing ring, etc., may also be provided between the first box body 21 and the second box body 22 .

[0077] Assuming that the first box body portion 21 covers the top of the second box body portion 22 , the first box body portion 21 can also be called an upper box cover, and the second box body portion 22 can also be called a lower box cover.

[0078] The present application embodiment provides a battery cell. Figures 3 to 8 The battery cell 10 includes a housing 11, a top cover 12, and an electrode assembly 14. The housing 11 has a receiving space 11a and an opening 11b. The top cover 12 is sealed at the opening 11b. The electrode assembly 14 is disposed within the receiving space 11a. The inner sidewall of the housing 11 is thinned near the bottom to form a thinned region 11c. The lowest point of the thinned region 11c is no higher than the lowest point of the electrode assembly 14.

[0079] Here, the housing may be cylindrical, flat, rectangular or in other shapes.

[0080] It should be noted that the height direction of the housing 11 described in the embodiments of the present application is the direction from the opening 11b to the accommodating space 11a, or the opposite direction from the opening 11b to the accommodating space 11a. When the housing 11 is cylindrical, the height direction of the housing 11 is the axial direction of the housing 11.

[0081] Here, the thinning of a portion of the inner wall of the housing 11 near the bottom means that the thinning of a portion of the inner wall of the housing 11 away from the opening 11 b , that is, the thinning of the lower region of the inner wall of the housing 11 .

[0082] The side of the housing 11 opposite to the opening 11 b is the bottom of the housing 11 .

[0083] It should be noted that the lower area of the housing 11 refers to the area below the middle of the housing 11 in the height direction, and the lower area of the electrode assembly 14 refers to the area below the middle of the electrode assembly 14 in the height direction.

[0084] Here, the lowest point of the thinned region 11c is no higher than the lowest point of the electrode assembly 14. In other words, the distance between the lowest point of the thinned region 11c and the bottom wall of the housing 11 is smaller than the distance between the lowest point of the electrode assembly 14 and the bottom wall of the housing 11. In other words, the distance between the lowest point of the thinned region 11c and the opening 11b is greater than the distance between the lowest point of the electrode assembly 14 and the opening 11b. In this way, when the electrode assembly 14 expands, the thinned region 11c can avoid the lower area of the electrode assembly 14.

[0085] Part of the inner wall of the shell 11 near the bottom is thinned to form a thinned area 11c. That is, under normal conditions, that is, when the electrode assembly 14 is not expanded, the gap between the thinned area 11c and the electrode assembly 14 is larger than the gap between other areas of the shell 11 except the thinned area 11c and the electrode assembly 14. This is beneficial to provide space for the expansion of the electrode assembly 14 and to improve the problem of stress concentration.

[0086] It should be noted that the specific method of connecting the top cover 12 and the housing 11 is not limited here, and can be, for example, welding, that is, the top cover 12 and the housing 11 are welded at the area located at the opening 11b.

[0087] Here, see Figure 4 The electrode assembly 14 is formed by winding a positive electrode sheet 141, a negative electrode sheet 142, and a separator 143. The separator 143 is used to separate the positive electrode sheet 141 and the negative electrode sheet 142, and plays an insulating role for the positive electrode sheet 141 and the negative electrode sheet 142.

[0088] For example, see Figure 3 and Figure 4 The positive electrode sheet 141 may include a positive electrode current collector 1411 and a positive electrode active material 1412 . The positive electrode current collector 1411 has two surfaces opposite to each other in its thickness direction. The positive electrode active material 1412 is disposed on either or both of the two opposite surfaces of the positive electrode current collector 1411 .

[0089] For example, see Figure 4The negative electrode sheet 142 may include a negative electrode current collector 1421 and a negative electrode active material 1422 . The negative electrode current collector 1421 has two opposite surfaces in its own thickness direction. The negative electrode active material 1422 is disposed on either or both of the two opposite surfaces of the negative electrode current collector 1421 .

[0090] The battery cell provided in the embodiment of the present application includes a shell 11, a top cover 12 and an electrode assembly 14. The inner wall of the shell 11 is thinned in a partial area near the bottom to form a thinned area 11c, and the lowest point of the thinned area 11c is set to be no higher than the lowest point of the electrode assembly 14. Therefore, when the electrode assembly 14 expands during a cycle, the thinned area 11c can avoid the lower area of the electrode assembly 14, providing the lower area of the electrode assembly 14 with a larger expansion space. To a certain extent, it can improve the problem of lithium plating caused by stress concentration between the lower area of the electrode assembly 14 and the shell 11 due to expansion, thereby improving the performance and service life of the battery cell 10.

[0091] For some examples, see Figures 5 to 8 The battery cell 10 further includes a buffer member 13 attached to the outer wall of the housing 11 , and the lowest point of the thinned region 11 c is not higher than the lowest point of the buffer member 13 .

[0092] The buffer member 13 can play a buffering role for the battery cells 10 . For example, when two adjacent battery cells 10 swell, the buffer member 13 can play a buffering role, thereby reducing the probability of the battery cells 10 being damaged.

[0093] Here, the buffer member 13 may also have a bonding function, so that adjacent battery cells 10 are bonded together through the buffer member 13 .

[0094] In addition, the buffer member 13 can also prevent the housings 11 of adjacent battery cells 10 from directly contacting each other, or reduce the contact area between the housings 11 of adjacent battery cells 10 , to a certain extent, thereby achieving a heat insulation effect.

[0095] In this embodiment, by providing a buffer 13, a buffering effect can be played on the battery cell 10, thereby improving the probability of the battery cell 10 being damaged. At the same time, when the electrode assembly 14 expands during a cycle, the thinning area 11c can form a circumvention for the lower area of the electrode assembly 14, providing the lower area of the electrode assembly 14 with a larger expansion space, and setting the lowest point of the thinning area 11c to be no higher than the lowest point of the buffer 13 can further avoid the problem of stress concentration caused by the thinning area 11c squeezing the buffer 13, thereby further improving the problem of lithium deposition caused by stress concentration between the lower area of the electrode assembly 14 and the outer shell 11 due to expansion, thereby improving the performance and service life of the battery cell 10.

[0096] For some examples, see Figures 5 to 8 The housing 11 includes multiple surfaces, including a first surface 11d, which is the largest surface among the multiple surfaces. The buffer 13 is attached to the first surface 11d. The buffer 13 includes two first connecting segments 131 spaced apart in the height direction of the battery cell 10 and two second connecting segments 132 spaced apart in the first direction. The two first connecting segments 131 and the two second connecting segments 132 are connected end to end, and the first direction intersects with the height direction of the battery cell 10. Among them, when projected on the plane where the first surface 11d is located, the projection of the first connecting segment 131 away from the opening 11b is located within the projection range of the thinned area 11c.

[0097] It should be noted that the first surface 11 d described in the embodiment of the present application is the large surface of the housing 11 , which is the surface with the largest area among the multiple surfaces of the housing 11 .

[0098] Taking the square battery cell 10 as an example, in the vertical state, the surface formed by the length and width directions of the battery cell 10 is the bottom surface of the battery cell 10, the surface formed by the length and height directions of the battery cell 10 is the large surface of the battery cell 10, that is, the first surface 11d, and the surface formed by the width and height directions of the battery cell 10 is the side surface of the battery cell 10.

[0099] Exemplarily, the buffer member 13 is a slit-frame structure. Specifically, the buffer member 13 includes two first connecting segments 131 spaced apart in the height direction of the battery cell 10 and two second connecting segments 132 spaced apart in the first direction. The two first connecting segments 131 and the two second connecting segments 132 are connected end to end, and the first direction intersects the height direction of the battery cell 10. Here, the two first connecting segments 131 extend along the first direction, and the two second connecting segments 132 extend along the height direction of the battery cell 10.

[0100] Here, the first direction intersecting the height direction of the battery cell 10 means that the first direction intersects and is not parallel to the height direction of the battery cell 10. For example, the first direction and the height direction of the battery cell 10 are perpendicular to each other.

[0101] Exemplarily, the first direction is the length direction of the battery cell 10 .

[0102] In the related art, after the battery is installed with a buffer part with a hole frame structure in the module, after circulation, the upper area of the battery cell is thinned and the expansion force is small, while the lower area of the battery cell is not thinned and the expansion force is greater, which will cause stress concentration in the area of the lower area of the battery cell where the expansion force is large, thereby causing problems such as lithium plating.

[0103] In the battery cell of the embodiment of the present application, the projection of the first connecting section 131 away from the opening 11b is projected on the plane where the first surface 11d is located, and is located within the projection range of the thinning area 11c. That is, the inner side walls of the shell 11 corresponding to the first connecting section 131 away from the opening 11b are thinned to form a thinning area 11c. In other words, the inner side wall of the shell 11 in the area where the buffer part 13 is attached is provided with a thinning area 11c, which is used to avoid the electrode assembly 14 and the buffer part 13, thereby improving the problem that the lower area of the electrode assembly 14 causes the shell 11 to expand due to expansion, and then squeezes the buffer part 13 to generate stress concentration and cause lithium deposition, thereby improving the performance and service life of the battery cell 10.

[0104] Illustratively, the battery cell 10 includes a bottom support plate, which is disposed within the housing 11 and is located at the bottom of the electrode assembly 14. The bottom support plate supports the electrode assembly 14, which helps to evenly distribute the force on the bottom of the electrode assembly 14 and avoids stress concentration in the electrode assembly 14.

[0105] In some embodiments, the distance between the lowest point of the thinned region 11 c and the bottom wall of the housing 11 is L1, where 0≤L1≤10 mm.

[0106] For example, 0, 0.5mm, 1mm, 1.2mm, 1.5mm, 1.8mm, 2mm, 2.5mm, 3mm, 3.2mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, 10mm, etc.

[0107] It can be understood that the thinned area 11c is mainly used to avoid the lower area of the electrode assembly 14 and the first connecting section 131 of the buffer 13 close to the bottom of the shell 11. Therefore, the position of the thinned area 11c is specifically determined according to the position of the electrode assembly 14 and the buffer 13.

[0108] When the distance between the lowest point of the thinned region 11 c and the bottom wall of the housing 11 is 0, the thinned region 11 c extends to the bottom wall of the housing 11 .

[0109] In this embodiment, by setting the distance between the lowest point of the thinned area 11c and the bottom wall of the shell 11 to 0-10mm, it is possible to effectively improve the problem of stress concentration between the lower area of the electrode assembly 14 and the shell 11 due to expansion, thereby causing lithium deposition, while ensuring that the shell 11 has sufficient strength.

[0110] For some examples, see Figures 6 to 8The size of the housing 11 in the height direction of the battery cell 10 is L, and the size of the thinned area 11c in the height direction of the battery cell 10 is L2, wherein,

[0111] For example, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, and so on.

[0112] here, It refers to the ratio of the height of the thinned area 11 c to the shell 11 . The larger the ratio, the better the avoidance effect of the thinned area 11 c . The smaller the ratio, the better the structural strength of the shell 11 .

[0113] It can be understood that by setting the ratio of the size of the thinned area 11c in the height direction of the battery cell 10 to the size of the shell 11 in the height direction of the battery cell 10 to 0.03-0.15, the shell 11 can have sufficient structural strength while the thinned area 11c can effectively avoid the electrode assembly 14 and the buffer 13.

[0114] For some examples, see Figures 6 to 8 The wall thickness of the thinned area 11c is H1, and the wall thickness of the other areas of the shell 11 except the thinned area 11c is H, wherein,

[0115] For example, 0.3, 0.35, 0.4, 0.46, 0.5, 0.58, 0.6, 0.65, 0.7, 0.72, 0.8, 0.84, 0.9, etc.

[0116] here, It refers to the ratio of the wall thickness of the thinning area 11c to the wall thickness of other areas of the shell 11 except the thinning area 11c. The larger the ratio, the better the structural strength of the thinning area 11c, that is, the better the structural strength of the shell 11. The smaller the ratio, the better the avoidance effect of the thinning area 11c.

[0117] In this embodiment, by setting the ratio of the wall thickness of the thinned area 11c to the wall thickness of other areas of the shell 11 except the thinned area 11c to 0.3-0.9, the thinned area 11c can have sufficient structure, that is, the shell 11 has sufficient structural strength, and the thinned area 11c can effectively avoid the electrode assembly 14 and the buffer part 13.

[0118] For some embodiments, please refer to Figures 6 to 8 The wall thickness of the thinned area 11c is H1, and the wall thickness of the outer shell 11 other than the thinned area 11c is H, wherein,

[0119] For example, 0.5, 0.53, 0.55, 0.58, 0.6, 0.64, 0.65, 0.69, 0.7, 0.72, 0.73, 0.75, 0.77, 0.8, and so on.

[0120] In this embodiment, by setting the ratio of the wall thickness of the thinned area 11c to the wall thickness of other areas of the shell 11 except the thinned area 11c to 0.5-0.8, the thinned area 11c can be further made to have sufficient structure, that is, the shell 11 has sufficient structural strength, and the thinned area 11c can further effectively avoid the electrode assembly 14 and the buffer part 13.

[0121] For some examples, see Figures 6 to 8 The wall thickness of the thinned area 11c is H1, where 0.25mm≤H1≤1.45mm.

[0122] For example, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm, 1.25mm, 1.3mm, 1.35mm, 1.4mm, 1.45mm, and so on.

[0123] In this embodiment, by setting the wall thickness of the thinned area 11c to 0.25mm-1.45mm, the thinned area 11c can have sufficient structure, that is, the shell 11 has sufficient structural strength, and the thinned area 11c can effectively avoid the electrode assembly 14 and the buffer member 13.

[0124] For some examples, see Figures 6 to 8 The wall thickness of the outer shell 11 except the thinned area 11c is H, 0.3mm≤H≤1.5mm.

[0125] For example, 0.3mm, 0.36mm, 0.4mm, 0.48mm, 0.5mm, 0.57mm, 0.6mm, 0.67mm, 0.7mm, 0.77mm, 0.8mm, 0.83mm, 0.9mm, 0.96mm, 1mm, 1.07mm, 1.1mm, 1.16mm, 1.2mm, 1.27mm, 1.3mm, 1.38mm, 1.4mm, 1.46mm, 1.5mm, and the like.

[0126] In this embodiment, by setting the wall thickness of the outer shell 11 other than the thinned area 11 c to 0.3 mm-1.5 mm, the outer shell 11 can have sufficient strength, and it is beneficial to reduce the material used and the space occupied by the outer shell 11.

[0127] For some embodiments, please refer to Figures 6 to 8 The wall thickness of the outer shell 11 other than the thinned area 11 c is H, the wall thickness of the thinned area 11 c is H1, and 0.05 mm ≤ H-H1 ≤ 0.7 mm.

[0128] For example, 0.05mm, 0.07mm, 0.1mm, 0.16mm, 0.2mm, 0.28mm, 0.3mm, 0.36mm, 0.4mm, 0.48mm, 0.5mm, 0.57mm, 0.6mm, 0.67mm, 0.7mm, etc.

[0129] Here, H-H1 refers to the difference between the wall thickness of other areas of the shell 11 except the thinning area 11c and the wall thickness of the thinning area 11c. The smaller the difference, the better the structural strength of the thinning area 11c, that is, the better the structural strength of the shell 11, and the larger the difference, the better the avoidance effect of the thinning area 11c.

[0130] In this embodiment, by setting the difference between the wall thickness of other areas of the shell 11 except the thinning area 11c and the wall thickness of the thinning area 11c to 0.05mm-0.7mm, the thinning area 11c can have sufficient structure, that is, the shell 11 has sufficient structural strength, and the thinning area 11c can effectively avoid the electrode assembly 14 and the buffer part 13.

[0131] It should be noted that the dimension L of the housing 11 in the height direction of the battery cell 10; the distance L1 between the lowest point of the thinned area 11c and the bottom wall of the housing 11; the wall thickness of other areas of the housing 11 except the thinned area 11c is H; the values of the wall thickness H1 of the thinned area 11c can be obtained by testing and calculation using instruments such as a high-precision thickness gauge and a vernier caliper at room temperature.

[0132] In the description of this application, the descriptions with reference to the terms "in one embodiment", "in some embodiments", "in other embodiments", "in yet other embodiments", or "exemplary" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In this application, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine different embodiments or examples described in this application and features of different embodiments or examples, unless they are mutually inconsistent.

[0133] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application are intended to be within the scope of protection of the present application.

Claims

1. A battery cell, characterized in that: include: a housing having a receiving space and an opening; A top cover and a sealing cover are provided at the opening; an electrode assembly, disposed in the accommodation space; Part of the inner side wall of the shell near the bottom is thinned to form a thinned area, and the lowest point of the thinned area is not higher than the lowest point of the electrode assembly.

2. The battery cell according to claim 1, wherein: The battery cell further includes a buffer member attached to the outer wall of the shell, and the lowest point of the thinned area is not higher than the lowest point of the buffer member.

3. The battery cell according to claim 2, characterized in that: The housing includes multiple surfaces, including a first surface having the largest area among the multiple surfaces; the buffer member is attached to the first surface, the buffer member includes two first connecting segments spaced apart in a height direction of the battery cell and two second connecting segments spaced apart in the first direction, the two first connecting segments and the two second connecting segments being connected end to end, and the first direction intersecting with the height direction of the battery cell; Wherein, when projected onto the plane where the first surface is located, the projection of the first connecting segment away from the opening is located within the projection range of the thinning area.

4. The battery cell according to claim 1, wherein: The distance between the lowest point of the thinned area and the bottom wall of the shell is L1, where 0≤L1≤10mm.

5. The battery cell according to claim 1, characterized in that The size of the housing in the height direction of the battery cell is L, and the size of the thinned area in the height direction of the battery cell is L2, wherein:

6. The battery cell according to claim 1, characterized in that The wall thickness of the thinned area is H1, and the wall thickness of the other areas of the shell except the thinned area is H, wherein, 7. The battery cell according to claim 6, characterized in that The wall thickness of the thinned area is H1, and the wall thickness of the other areas of the shell except the thinned area is H, wherein, 8. The battery cell according to claim 1, wherein: The wall thickness of the thinned area is H1, wherein 0.25 mm ≤ H1 ≤ 1.45 mm.

9. The battery cell according to claim 1, characterized in that The wall thickness of the thinned area is H1, and the wall thickness of other areas of the shell except the thinned area is H, wherein 0.05 mm ≤ H-H1 ≤ 0.7 mm.

10. A battery, characterized in that: The battery comprises at least one battery cell according to any one of claims 1 to 9.

11. An electrical device, characterized in that: The battery according to claim 10 is used to provide electrical energy to the electrical device.

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