Battery cells, batteries, and power consumption devices

Abstract

The present application discloses a battery cell, a battery, and a power consumption device. The battery cell includes a shell, an electrode assembly, and a buffer member. The shell includes two first side walls arranged opposite to each other along a first direction, and the distance between the two first side walls in the first direction is D1. The electrode assembly is housed in the shell. M electrode assemblies are provided, where M is a positive integer greater than 0. In a fully charged state, the sum of the sizes of the M electrode assemblies along the first direction is D2. The buffer member is housed in the shell. N buffer members are provided, where N is a positive integer greater than 0. The N buffer members and the M electrode assemblies are stacked along the first direction. The buffer member is configured to be compressible, and the sum of the sizes of the N buffer members along the first direction in an uncompressed state is D3. D1, D2, and D3 satisfy 0.9≦(D2+D3) / D1≦1.5. The embodiment of the present application can improve the cycle characteristics of the battery cell and reduce an increase in the expansion force.

Description

Technical Field

[0001] This application claims the priority of Chinese Patent Application No. 202210379965.0, titled "Battery Cell, Battery, and Power Consumption Device", filed on April 12, 2022, and all the contents of this application are incorporated herein by reference.

[0002] This application relates to the field of batteries, and particularly to battery cells, batteries, and power consumption devices.

Background Art

[0003] Battery cells are widely used in electronic devices such as mobile phones, laptops, electric bicycles, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools. Battery cells include nickel-cadmium battery cells, nickel-metal hydride battery cells, lithium-ion battery cells, and secondary alkaline zinc-manganese battery cells, etc.

[0004] In the development of battery technology, how to improve the cycle characteristics of battery cells is an important research direction in battery technology.

Summary of the Invention

[0005] This application provides a battery cell that can improve the cycle characteristics of the battery cell, a manufacturing method and a manufacturing system thereof, a battery, and a power consumption device.

[0006] In a first aspect, the present application provides a battery cell comprising a shell, electrode assemblies, and buffer members. The shell includes two first side walls arranged opposite to each other along a first direction, with the distance between the two first side walls in the first direction being D1. Electrode assemblies are housed within the shell. There are M electrode assemblies, where M is a positive integer greater than 0. In a fully charged state, the sum of the sizes of the M electrode assemblies along the first direction is D2. Buffer members are housed within the shell. There are N buffer members, where N is a positive integer greater than 0. The N buffer members and M electrode assemblies are stacked along the first direction. The buffer members are configured to be compressible, and the sum of the sizes of the N buffer members in an uncompressed state along the first direction is D3. D1, D2, and D3 satisfy 0.9 ≤ (D2 + D3) / D1 ≤ 1.5.

[0007] In the above proposed technology, the buffer material can limit the deformation of the electrode assembly to some extent when the battery cell is first charged, improve the uniformity of the external force distribution of the electrode assembly, reduce the risk of wrinkling of the electrode sheets of the electrode assembly, and extend the life of the electrode assembly. During the battery cell cycle, the buffer material is compressed when pressed by the electrode assembly, providing space for the expansion of the electrode assembly, reducing the force acting between the shell and the electrode assembly, and improving the cycle characteristics of the electrode assembly. By limiting the value of (D2+D3) / D1 to 0.9~1.5, the above proposed technology can reduce the risk of wrinkling of the electrode sheets, reduce the amount of buffer material used, improve the energy density of the battery cell, reduce the expansion force of the electrode assembly, and improve the cycle characteristics of the electrode assembly.

[0008] In some embodiments, D1, D2, and D3 satisfy 0.98 ≤ (D2 + D3) / D1 ≤ 1.25.

[0009] In some embodiments, the first direction is parallel to the thickness direction of the battery cell.

[0010] In some embodiments, D2 and D3 satisfy D3 ≤ 0.25·D2. The above technical proposal can reduce the amount of buffer material used, improve the energy density of the battery cell, and improve the cycle characteristics of the electrode assembly.

[0011] In some embodiments, the electrode assembly includes a first electrode sheet, which includes a first body and a first tab drawn out from one end of the first body in a second direction, the second direction being perpendicular to the first direction. The size of the buffer member in the second direction is H1, and the first body is provided with a first active material layer, the size of the first active material layer in the second direction is H2. H1 and H2 satisfy H1 ≥ 0.85·H2.

[0012] The main reason for the expansion of the electrode assembly is the expansion of the active material layer during the charging process. In the above proposed technology, by limiting the value of H1 to 0.85·H2 or higher, more than 85% of the expansion of the second direction region of the first active material layer is absorbed by the buffer member, reducing the pressure on the first active material layer and improving the cycle characteristics of the electrode assembly.

[0013] In some embodiments, the first active material layer includes a base region and a thin-walled region connected to the base region, wherein the thickness of the thin-walled region is less than the thickness of the base region. In a second direction, the thin-walled region is located on the side of the base region closer to the first tab. In a second direction, both ends of the buffer member extend beyond the base region.

[0014] Since the expansion force generated when the base region expands is greater than that of the thin-walled region, the above technical proposal effectively absorbs the expansion of the base region by having both ends of the buffer member in the second direction extend beyond the base region, thereby improving the cycle characteristics of the electrode assembly.

[0015] In some embodiments, the electrode assembly further includes a separator, and the separator and the first body are arranged in a stack. The size of the separator along the second direction is H3. H1 and H3 satisfy H1 ≤ 1.1·H3. In the second direction, the portion of the buffer material that extends beyond the separator does not absorb the expansion of the electrode assembly, but leads to an increase in the volume and weight of the buffer material. In the above technical proposal, by setting the value of H1 to 1.1·H3 or less, the amount of buffer material used is reduced and the energy density of the battery cell is improved.

[0016] In some embodiments, in the second direction, neither end of the buffer member extends beyond the separator. This reduces the amount of buffer member used, lowers the risk of the buffer member interfering with other components, and improves the energy density of the battery cell.

[0017] In some embodiments, the electrode assembly includes a flat region and two bent regions, the two bent regions each located on either side of the flat region along a third direction, the third direction being perpendicular to the first direction. The size of the buffer member along the third direction is L1, the size of the electrode assembly along the third direction in a fully charged state is L2, and the size of the electrode assembly along the first direction in a fully charged state is D4. L1, L2, and D4 satisfy L1 ≥ 0.85(L2 - D4).

[0018] Because the gap between the bent region and the first side wall of the electrode assembly is large, the expansion force due to the bent region is small. Because the gap between the flat region and the first side wall of the electrode assembly is small, the expansion force due to the flat region is large. In the above proposed technology, by limiting the value of L1 to 0.85 (L2-D4) or higher, more than 85% of the expansion of the third direction region of the flat region is absorbed by the buffer member, thereby ensuring the cycle characteristics of the flat region.

[0019] In some embodiments, in the third direction, both ends of the buffer member extend beyond the flat region. The buffer member can effectively absorb the expansion of the flat region and improve the cycle characteristics of the flat region.

[0020] In some embodiments, L1 and L2 satisfy L1 ≤ 1.1·L2. In the third direction, the portion of the buffer member that extends beyond the electrode assembly does not absorb the expansion of the electrode assembly, but leads to an increase in the volume and weight of the buffer member. In this embodiment, by setting the value of L1 to 1.1·L2 or less, the amount of buffer member is reduced and the energy density of the battery cell is improved.

[0021] In some embodiments, the area of ​​the projection of the first side wall on the inner surface of the buffer member in the first direction is S1, the area of ​​the inner surface of the first side wall is S2, and S1 and S2 satisfy S1 ≤ 0.95·S2.

[0022] The above proposed technology can reduce the overall amount of cushioning material used, increase the space for other components within the shell, and improve the energy density and service life of the battery cell.

[0023] In some embodiments, the size of each buffer member in the first direction in the uncompressed state is D5, where D5 satisfies 0.1 mm ≤ D5 ≤ 10 mm.

[0024] In some embodiments, the compressibility f of the buffer member at a pressure of 2 MPa satisfies 1% ≤ f ≤ 99%.

[0025] In some embodiments, the cushioning member is incorporated into the electrode assembly. The cushioning member incorporated into the electrode assembly can be placed in the housing together with the electrode assembly, thereby simplifying the assembly process. The electrode assembly can also suppress vibration of the cushioning member when the battery cell is subjected to external shocks, reducing the risk of displacement of the cushioning member.

[0026] In some embodiments, there are multiple electrode assemblies. A buffer member is provided between at least two adjacent electrode assemblies. By providing the buffer member between two adjacent electrode assemblies, the risk of the buffer member swaying when the battery cell is subjected to an external impact can be reduced.

[0027] In some embodiments, the buffer member has a flat plate structure. The flat plate structure is easy to form and improves the uniformity of the external force distribution of the electrode assembly when the electrode assembly expands.

[0028] In a second aspect, an embodiment of the present application provides a battery including the battery cell described in any one of the embodiments of the first aspect.

[0029] In a third aspect, an embodiment of the present application provides a power consumption device including the battery cell described in any one of the embodiments of the first aspect, wherein the battery cell supplies electrical energy.

[0030] In a fourth aspect, an embodiment of the present application provides a method for manufacturing a battery cell, including the steps of providing a shell including two first side walls oppositely arranged along a first direction, providing an electrode assembly and a buffer member, and placing the electrode assembly and the buffer member into the shell. The distance between the two first side walls in the first direction is D1. M electrode assemblies are provided, where M is a positive integer greater than 0. In a fully charged state, the sum of the sizes of the M electrode assemblies along the first direction is D2. There are N buffer members, where N is a positive integer greater than 0, and the N buffer members and the M electrode assemblies are laminated along the first direction. The buffer member is configured to be compressible, and the sum of the sizes of the N buffer members along the first direction in an uncompressed state is D3. D1, D2, and D3 satisfy 0.9 ≦ (D2 + D3) / D1 ≦ 1.5.

[0031] In a fifth aspect, embodiments of the present application provide a battery cell manufacturing system comprising a first supplying device, a second supplying device, and an assembly device. The first supplying device is used to provide a shell comprising two first side walls arranged opposite to each other along a first direction. The second supplying device is used to provide electrode assemblies and buffer members. The assembly device is used to mount the electrode assemblies and buffer members within the shell. The distance between the two first side walls along the first direction is D1. There are M electrode assemblies, where M is a positive integer greater than 0, and in a fully charged state, the sum of the sizes of the M electrode assemblies along the first direction is D2. There are N buffer members, where N is a positive integer greater than 0, and the N buffer members and the M electrode assemblies are stacked along the first direction, and the buffer members are configured to be compressible, and the sum of the sizes of the N buffer members along the first direction in an uncompressed state is D3. D1, D2, and D3 satisfy 0.9 ≤ (D2 + D3) / D1 ≤ 1.5. [Brief explanation of the drawing]

[0032] The features, advantages, and technical effects of exemplary embodiments of the present application will be described below with reference to the drawings. [Figure 1] This is a schematic diagram of the structure of a vehicle according to several embodiments of the present invention. [Figure 2] This is a schematic diagram of a battery disassembled according to several embodiments of the present invention. [Figure 3] Figure 2 is a schematic diagram of the battery module after disassembly. [Figure 4] This is a schematic diagram of a disassembled battery cell according to several embodiments of the present invention. [Figure 5] This is a schematic diagram of the structure of a battery cell according to some embodiments of the present invention. [Figure 6] This is a schematic cross-sectional view of an electrode assembly of a battery cell according to some embodiments of the present invention. [Figure 7] This is a schematic cross-sectional view of a battery cell according to several embodiments of the present invention. [Figure 8] These are schematic cross-sectional views of an electrode assembly and a buffer member of a battery cell according to some embodiments of the present application. [Figure 9] This is a schematic diagram of the structure of a battery cell according to some other embodiments of the present invention. [Figure 10] Schematic diagrams of the structure of battery cells according to some other embodiments of the present invention. [Figure 11] This is a schematic diagram of the structure of a battery cell according to some further embodiments of the present invention. [Figure 12] This is a schematic diagram illustrating the flow of a manufacturing method for a battery cell according to some embodiments of the present invention. [Figure 13] This is a schematic block diagram of a battery cell manufacturing system according to some embodiments of the present invention. [Figure 14] This is a schematic diagram of the structure of a battery cell according to some embodiments of the present invention. [Modes for carrying out the invention]

[0033] To further clarify the purpose, technical concept and advantages of the embodiments of this application, the technical concept in the embodiments of this application is described below with reference to the drawings of the embodiments of this application, although it is clear that the embodiments described are only a part of the embodiments of this application and not all of them. Any other embodiments obtained by a person skilled in the art without expending any creative effort based on the embodiments of this application are all within the scope of protection of this application.

[0034] Unless otherwise defined, all technical and scientific terms used in this Application have the same meaning as those generally understood by those skilled in the art. In this Application, terms used in the Specification are used solely to describe specific embodiments and are not intended to limit the Application. The terms “includes,” “equip,” and “possess,” and their variations, in the Specification, Claims, and the description of the above drawings, are intended to cover non-exclusive inclusion. Terms such as “first,” “second,” etc., in the Specification, Claims, and the above drawings are used to distinguish different subjects and are not intended to describe a specific order or primary and secondary relationship.

[0035] Where the term "Examples" is used in this Application, it means that certain features, structures, or properties described with reference to the Examples may be included in at least one Example of this Application. The appearance of the term in different places in the Specification does not necessarily refer to the same Example, nor does it refer to mutually exclusive, independent, or alternative Examples.

[0036] In this description, unless otherwise specifically defined or limited, the terms “attach,” “connect,” “join,” and “assemble” should be understood in a broad sense, and may include, for example, a fixed connection, a removable connection, or a solid connection, or a direct connection, an indirect connection via an intermediate medium, or internal communication between two components. A person skilled in the art will be able to understand the specific meaning of the above terms in this specification depending on the specific circumstances.

[0037] In this application, the terms "and / or" merely describe the relationship between related objects, meaning that three relationships exist. For example, in the case of A and / or B, it can represent three situations: A existing alone, A and B existing simultaneously, and B existing alone. In addition, the symbol " / " in this application generally indicates that the preceding and succeeding related objects are in an "or" relationship.

[0038] In the embodiments of this application, the same reference numerals represent the same components, and in different embodiments, detailed descriptions of the same components are omitted for brevity. The thickness, length, width, and other dimensions of the various components in the embodiments of this application shown in the attached drawings, as well as the thickness, length, width, and other dimensions of the overall integrating device, are merely illustrative, and it should be understood that this application does not constitute any limitation.

[0039] As used in this application, "multiple" means two or more (including two).

[0040] In this application, the battery cell may include lithium-ion secondary battery cells, lithium-ion primary battery cells, lithium-sulfur battery cells, sodium lithium-ion battery cells, sodium-ion battery cells, or magnesium-ion battery cells, and the embodiments of this application are not limited thereto. The shape of the battery cell may be cylindrical, flattened, rectangular, or other shapes, and the embodiments of this application are not limited thereto.

[0041] As referred to in the embodiments of this application, a battery refers to a single physical module containing one or more battery cells to provide higher voltage and capacity. For example, a battery referred to in this application may include a battery module or a battery pack. A battery typically includes a housing for packing one or more battery cells. The housing can prevent liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0042] A battery cell comprises an electrode assembly and an electrolyte, the electrode assembly comprising a positive electrode sheet, a negative electrode sheet, and a separator. The battery cell operates primarily by the movement of metal ions between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer being coated on the surface of the positive electrode current collector. The positive electrode current collector comprises a positive electrode coated region and a positive electrode tab connected to the positive electrode coated region, the positive electrode active material layer being coated on the positive electrode coated region and not on the positive electrode tab. Taking a lithium-ion battery cell as an example, the material of the positive electrode current collector may be aluminum, the positive electrode active material layer may contain a positive electrode active material, and the positive electrode active material may be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer being coated on the surface of the negative electrode current collector, the negative electrode current collector including a negative electrode coated region and a negative electrode tab connected to the negative electrode coated region, the negative electrode active material layer being coated on the negative electrode coated region and not on the negative electrode tab. The material of the negative electrode current collector may be copper, the negative electrode active material layer may contain a negative electrode active material, and the negative electrode active material may be carbon, silicon, or the like. The material of the separator may be polypropylene (PP) or polyethylene (PE), or the like.

[0043] The battery cell further includes a shell, within which a storage chamber is formed for housing the electrode assembly. The shell protects the electrode assembly from the outside, preventing external foreign matter from affecting the charging or discharging of the electrode assembly.

[0044] During the charging process, the electrode assembly expands. The expanded electrode assembly compresses the shell, and therefore the shell exerts a reaction force on the electrode assembly, limiting its expansion. If the force between the electrode assembly and the shell is too large, the electrolyte between the electrode sheets may be squeezed out, potentially affecting the cycle characteristics of the electrode assembly.

[0045] The inventors attempted to create a gap between the electrode assembly and the shell. This gap provides space for the electrode assembly to expand, thereby reducing the force acting between the shell and the electrode assembly and improving the electrode assembly's cycle characteristics. However, the inventors discovered that when the electrode assembly is first charged, the presence of this gap means that the electrode assembly is not constrained by the shell, or the constraining force by the shell is weak. As a result, the uniformity of the forces the electrode assembly experiences decreases, and there is a risk of wrinkles forming in the electrode sheet. Wrinkles in the electrode sheet can lead to the deposition of metal ions from the electrode sheet during subsequent cycles, shortening the cycle life of the electrode assembly and potentially causing it to fail.

[0046] With this in mind, the inventors have installed a buffer member within the shell. The buffer member limits the deformation of the electrode assembly to some extent when the battery cell is first charged, improves the uniformity of the external force distribution of the electrode assembly, reduces the risk of wrinkles in the electrode sheets of the electrode assembly, and extends the life of the electrode assembly. During the battery cell cycle process, the buffer member is compressed when pressed by the electrode assembly, providing space for the electrode assembly to expand, reducing the force acting between the shell and the electrode assembly, and improving the cycle characteristics of the electrode assembly. Based on calculations and tests, the inventors have found that the cycle characteristics of the electrode assembly can be improved by setting the size of the buffer member according to the size of the electrode assembly and the size of the shell.

[0047] The battery cell described in the embodiment of this application is suitable for batteries and power consumption devices using the battery cell.

[0048] Power-consuming devices may include vehicles, mobile phones, portable devices, laptop computers, ships, spacecraft, electric toys, and power tools. Vehicles may be fuel-powered vehicles, gasoline vehicles, or new energy vehicles, and new energy vehicles may be pure electric vehicles, hybrid vehicles, or vehicles with extended range. Spacecraft include aircraft, rockets, space shuttles, and other spacecraft. Electric toys include stationary or mobile electric toys such as game consoles, electric car toys, electric boat toys, and electric airplane toys. Power tools include electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, metal cutting power tools such as concrete vibrators and planers, grinding power tools, assembly power tools, and railway power tools. The embodiments of this application are not particularly limited to the power-consuming devices described above.

[0049] For the sake of explanation, the following embodiments will be described using the example where the power consumption device is a vehicle.

[0050] Figure 1 is a schematic diagram of the structure of a vehicle according to several embodiments of the present application.

[0051] As shown in Figure 1, a battery 2 is provided inside the vehicle 1, and the battery 2 may be located at the bottom, head, or tail of the vehicle 1. The battery 2 may supply power to the vehicle 1, and for example, the battery 2 may function as the operating power source for the vehicle 1.

[0052] Vehicle 1 may further include a controller 3 and a motor 4, the controller 3 for controlling a battery 2 to supply power to the motor 4, and is used, for example, for the power needs of starting, navigating, and driving Vehicle 1.

[0053] In some embodiments of the present invention, the battery 2 not only functions as an operating power source for the vehicle 1, but can also serve as a drive power source for the vehicle 1, supplying driving power to the vehicle 1 by substituting or partially substituting fuel or natural gas.

[0054] Figure 2 is a schematic diagram of a battery according to some embodiments of the present invention.

[0055] As shown in Figure 2, the battery 2 includes a casing 5 and battery cells (not shown), with the battery cells housed inside the casing 5.

[0056] The casing 5 houses the battery cells, and the casing 5 may have various structures. In some embodiments, the casing 5 may include a first casing section 5a and a second casing section 5b, the first casing section 5a and the second casing section 5b are joined together, and both the first casing section 5a and the second casing section 5b define a storage space 5c for housing the battery cells. The second casing section 5b may be a hollow structure with one end open, and the first casing section 5a is a plate-like structure, with the first casing section 5a joined to the open side of the second casing section 5b to form a casing 5 having a storage space 5c. The first casing section 5a and the second casing section 5b may also be hollow structures with one side open, with the open side of the first casing section 5a joined to the open side of the second casing section 5b to form a casing 5 having a storage space 5c. Of course, the first box-shaped part 5a and the second box-shaped part 5b may have various shapes, such as a cylinder or a rectangular parallelepiped.

[0057] To improve the sealing performance of the first box section 5a and the second box section 5b after connection, a sealing member such as a sealant or a sealing ring may be provided between the first box section 5a and the second box section 5b.

[0058] When the first box section 5a is fitted onto the top of the second box section 5b, the first box section 5a may be called the upper cover and the second box section 5b may be called the lower box section.

[0059] In battery 2, there may be one battery cell or multiple battery cells. If there are multiple battery cells, the battery cells may be connected in series, in parallel, or in series-parallel connection, where some of the battery cells are connected in series and others in parallel. Multiple battery cells may be directly connected in series, in parallel, or in series-parallel connection, and then the assembly of multiple battery cells may be housed together in the box 5. Of course, multiple battery cells may be connected in series, in parallel, or in series-parallel connection to form a battery module 6, and then multiple battery modules 6 may be connected in series, in parallel, or in series-parallel connection and housed together in the box 5.

[0060] Figure 3 is a schematic diagram of the battery module shown in Figure 2 after disassembly.

[0061] In some embodiments, as shown in Figure 3, there are multiple battery cells 7. First, multiple battery cells 7 are connected in series, in parallel, or in series-parallel to form a battery module 6, and then the multiple battery modules 6 are connected in series, in parallel, or in series-parallel and housed together as a single unit in a box.

[0062] Multiple battery cells 7 in the battery module 6 may be connected in parallel, in series, or in series-parallel by electrically connecting them to each other using busbar members.

[0063] Figure 4 is a schematic diagram of the disassembled battery cell according to some embodiments of the present application, and Figure 5 is a schematic diagram of the structure of a battery cell according to some embodiments of the present application, where the end cover is omitted. Figure 6 is a schematic cross-sectional view of the electrode assembly of a battery cell according to some embodiments of the present application.

[0064] As shown in Figures 4 to 6, the battery cell 7 of the embodiment of the present application includes a shell 20, an electrode assembly 10, and a buffer member 30. The shell 20 includes two first side walls 211 positioned opposite each other in a first direction X, with the distance between the two first side walls 211 in the first direction X being D1. There are M electrode assemblies 10, which are housed within the shell 20, and in a fully charged state, the sum of the sizes of the M electrode assemblies 10 along the first direction X is D2, where M is a positive integer greater than 0. There are N buffer members 30, which are housed within the shell 20 and stacked together with the M electrode assemblies 10 along the first direction X. The buffer members 30 are configured to be compressible, and the sum of the sizes of the N buffer members 30 in an uncompressed state along the first direction X is D3, where N is a positive integer greater than 0. D1, D2, and D3 satisfy 0.9 ≤ (D2 + D3) / D1 ≤ 1.5.

[0065] The shell 20 is a hollow structure whose interior serves as a storage chamber for housing the electrode assembly 10 and electrolyte. The shell 20 may have various shapes, such as a rectangular parallelepiped. The shape of the shell 20 may be determined according to the specific shape of the electrode assembly 10; for example, if the electrode assembly 10 has a rectangular parallelepiped structure, a rectangular parallelepiped shell can be used.

[0066] In this embodiment, the material of the shell 20 is not limited. For example, the shell 20 may be made of a hard material such as aluminum, steel, or plastic, or it may be made of an aluminum-plastic film, a steel-plastic film, or other soft material.

[0067] The two first side walls 211 are located on either side of the first direction X of the storage compartment. Exemplary, the size of the storage compartment along the first direction X is D1.

[0068] The value of D1 can be measured in various ways, for example, using calipers or microscopic marking such as mechanical cross-section / surface analysis.

[0069] The electrode assembly 10 includes a first electrode sheet 11 and a second electrode sheet 12, and the electrode assembly 10 operates primarily by the movement of metal ions between the first electrode sheet 11 and the second electrode sheet 12. Exemplarily, the electrode assembly 10 further includes a separator 13, which can electrically isolate the first electrode sheet 11 and the second electrode sheet 12.

[0070] The polarity of the first electrode sheet 11 and the polarity of the second electrode sheet 12 are opposite. Specifically, one of the first electrode sheet 11 and the second electrode sheet 12 is the positive electrode sheet, and the other is the negative electrode sheet.

[0071] M is a positive integer greater than 0, meaning that there may be one electrode assembly 10 or multiple electrode assemblies. If there are multiple electrode assemblies 10, the multiple electrode assemblies 10 may be stacked in the first direction X.

[0072] When fully charged, the electrode assembly 10 expands. Exemplarily, after manufacturing the battery cell 7, it is charged at a rate of 0.33C in a room temperature environment until fully charged. Once the battery cell 7 is fully charged, it is disassembled and the size D4 of each electrode assembly 10 along the first direction X in the fully charged state is measured with a caliper.

[0073] If only one electrode assembly 10 is provided inside the battery cell 7, the value of D2 is equal to D4. If multiple electrode assemblies 10 are provided inside the battery cell 7, the value of D2 is equal to the sum of the sizes D4 of the multiple electrode assemblies 10 along the first direction X.

[0074] If multiple electrode assemblies 10 are provided, the sizes D4 along the first direction X of different electrode assemblies 10 may be the same or different.

[0075] N is a positive integer greater than 0, meaning that there may be one or more buffer members 30.

[0076] N buffer members 30 and M electrode assemblies 10 are stacked along a first direction X. In the embodiments of this application, the stacking order of the buffer members 30 and electrode assemblies 10 in the first direction X is not limited.

[0077] In some examples, there is one buffer member 30 and multiple electrode assemblies 10. The multiple electrode assemblies 10 may be arranged sequentially along a first direction X to form a single electrode unit, and the buffer member 30 may be provided on one side of the electrode unit in the first direction X. Optionally, the buffer member 30 may be provided between two adjacent electrode assemblies 10.

[0078] In some other examples, there are multiple buffer members 30 and one electrode assembly 10. The multiple buffer members 30 may be arranged sequentially along a first direction X to form a single buffer unit, and the electrode assembly 10 may be located on one side of the buffer unit in the first direction X. Optionally, the electrode assembly 10 may be located between two adjacent buffer members 30.

[0079] In some other examples, there are multiple buffer members 30 and multiple electrode assemblies 10. The stacking order of the multiple buffer members 30 and the multiple electrode assemblies 10 in the first direction X may be freely set as needed. For example, each buffer member 30 may be adjacent to an electrode assembly 10, or adjacent to another buffer member 30.

[0080] The buffer member 30 is compressed when pressed by the electrode assembly 10, providing space for the expansion of the electrode assembly 10 and reducing the force acting between the first side wall 211 and the electrode assembly 10.

[0081] For example, the buffer member 30 has a certain elastic deformation capacity, is compressed by the electrode assembly 10 when the electrode assembly 10 is fully charged, and recovers at least some of the deformation when the electrode assembly 10 is fully discharged, thereby ensuring that the buffer member 30 is in contact with the electrode assembly 10, improving the uniformity of the external force distribution of the electrode assembly 10, and reducing the risk of wrinkles forming on the electrode sheets of the electrode assembly 10.

[0082] In the embodiments of the present application, the specific material of the buffer member 30 is not limited, and it is required to have a certain deformation capacity and to recover at least some of its deformation when the external force is removed. Exemplarily, if it is necessary to measure the size of each buffer member 30 along a first direction X in an uncompressed state, the battery cell 7 is disassembled to remove the buffer members 30, and then the size D5 of each buffer member 30 along a first direction X in an uncompressed state is measured with a caliper. Optionally, during the manufacture of the battery cell 7, the size D5 of the buffer member 30 along a first direction X in an uncompressed state is measured before the buffer member 30 is placed in the shell.

[0083] If only one buffer member 30 is provided inside the battery cell 7, the value of D3 is equal to the value of D5. If multiple buffer members 30 are provided inside the battery cell 7, the value of D3 is equal to the sum of the sizes D5 of the multiple buffer members 30 along the first direction X.

[0084] When multiple cushioning members 30 are provided, the sizes D5 along the first direction X in the uncompressed state of different cushioning members 30 may be the same or different.

[0085] In the embodiments of this application, the shape of the cushioning member 30 is not limited and may be plate-shaped, block-shaped, or have other irregular shapes.

[0086] The buffer member 30 suppresses deformation of the electrode assembly 10 to some extent when the battery cell 7 is charged for the first time, improves the uniformity of the external force distribution of the electrode assembly 10, reduces the risk of wrinkles forming on the electrode sheets of the electrode assembly 10, and extends the life of the electrode assembly 10. During the cycle process of the battery cell 7, the buffer member 30 is compressed when pressed by the electrode assembly 10, providing space for the expansion of the electrode assembly 10, reducing the force acting between the shell 20 and the electrode assembly 10, and improving the cycle characteristics of the electrode assembly 10.

[0087] The smaller the value of (D2+D3) / D1, the lower the utilization rate of the space inside the shell 20, the smaller the restraining force that the first side wall 211 exerts on the electrode assembly 10 during charging, and the higher the risk of wrinkles forming on the electrode sheet of the electrode assembly 10. The buffer member 30 can suppress deformation of the electrode assembly 10 to some extent when the battery cell 7 is charged for the first time, but if the value of (D2+D3) / D1 is too small, the buffer member 30 is less able to effectively suppress wrinkles in the electrode sheet. Taking this into consideration, the inventors have found that by setting (D2+D3) / D1 to 0.9 or higher, the utilization rate of the space can be improved and the risk of wrinkles forming on the electrode sheet can be reduced.

[0088] The larger the value of (D2+D3) / D1, the better the cushioning member 30 can suppress the deformation of the electrode assembly 10 when the battery cell 7 is charged for the first time. Of course, the larger the value of (D2+D3) / D1, the larger the space and weight occupied by the cushioning member 30, and the greater the amount of compression of the cushioning member 30 during the battery cell 7's cycle process. If the value of (D2+D3) / D1 is too large, the compressible amount of the cushioning member 30 placed in the shell becomes small, the amount of expansion that the cushioning member 30 can absorb becomes insufficient, and the expansion force of the electrode assembly 10 becomes too large. Taking this into consideration, the inventors reduce the amount of cushioning member 30 by setting (D2+D3) / D1 to 1.5 or less, thereby improving the energy density of the battery cell 7, reducing the expansion force of the electrode assembly 10, and improving the cycle characteristics of the electrode assembly 10.

[0089] Selectively, the value of (D2+D3) / D1 may be 0.9, 0.95, 0.98, 1, 1.1, 1.2, 1.25, 1.3, 1.4, or 1.5.

[0090] In some embodiments, D1, D2, and D3 satisfy 0.98 ≤ (D2 + D3) / D1 ≤ 1.25.

[0091] In some embodiments, the electrode assembly 10 includes a main body 14 and first tabs 15 and second tabs 16 drawn out from the main body 14. The main body 14 includes a positive electrode coating area, a positive electrode active material layer, a negative electrode coating area, a negative electrode active material layer, and a separator 13. One of the first tabs 15 and the second tabs 16 is the positive electrode tab, and the other is the negative electrode tab.

[0092] In this application, when fully charged, the size of the main body 14 along the first direction X is D4.

[0093] In some embodiments, the shell 20 includes a housing 21 and an end cover 22, the housing 21 having an opening and the end cover 22 fitting over the opening. Exemplarily, the housing 21 includes two first side walls 211.

[0094] The housing 21 may have an open structure on one side, and one end cover 22 may be provided to cover the opening of the housing 21. Optionally, the housing 21 may be configured as an open structure on both sides, and two end covers 22 may be provided, each covering two openings of the housing 21.

[0095] Exemplary, the end cover 22 is connected to the housing 21 by welding, adhesive, snap connections or other means.

[0096] In some embodiments, the first side wall 211 is a flat plate structure.

[0097] In some embodiments, an opening is provided at one end of the housing 21 in the second direction Y. Selectively, the first direction X is perpendicular to the second direction Y.

[0098] In some embodiments, the housing 21 includes two second side walls 212, the two second side walls 212 facing each other in a third direction Z. Selectively, the third direction Z is perpendicular to the first direction X and the second direction Y.

[0099] The two first side walls 211 and the two second side walls 212 are arranged alternately in the circumferential direction of the opening. Both ends of the first side wall 211 in the third direction Z are connected to the two second side walls 212, respectively.

[0100] In some embodiments, adjacent first sidewalls 211 and second sidewalls 212 are connected via an arc-shaped wall.

[0101] In some embodiments, the value of D1 may be measured by the following method: Measure the size D6 of the housing 21 along the first direction X with a caliper, and measure the wall thickness D7 of the first side wall 211 with a caliper. D1 = D6 - 2·D7.

[0102] During the battery cell 7's cycle, the first sidewall 211 may deform due to the expansion of the electrode assembly 10. Since the deformation of the end of the first sidewall 211 closest to the second sidewall 212 is small, the value measured by clamping the ends of the two first sidewalls 211 closest to the second sidewall 212 with calipers can be taken as D6.

[0103] In some embodiments, the battery cell 7 further includes two electrode terminals 40, which may be provided on the end cover 22. One electrode terminal 40 is electrically connected to the first electrode sheet 11 of the electrode assembly 10, and the other electrode terminal 40 is electrically connected to the second electrode sheet 12, thereby drawing electrical energy from the electrode assembly 10 out of the shell 20.

[0104] In some embodiments, the buffer member 30 may have a porous structure. Micropores in the buffer member 30 may be used to store electrolyte, and when the electrode assembly 10 expands and compresses the buffer member 30, the electrolyte in the buffer member 30 can be pushed out.

[0105] In some embodiments, the cushioning member 30 may be made of foam.

[0106] In some embodiments, the first direction X is parallel to the thickness direction of the battery cell 7. In the battery, multiple battery cells 7 may be stacked along the first direction X.

[0107] In some embodiments, D2 and D3 satisfy D3 ≤ 0.25·D2.

[0108] When the value of D2 is constant, the larger the value of D3, the larger the volume and weight of the buffering member 30, and the lower the gravimetric energy density of the battery cell 7. The inventors found that when the value of D3 exceeds a predetermined range, the effect of the buffering member 30 in improving the cycle characteristics of the electrode assembly 10 does not further improve with increasing D3. Through testing, the inventors found that by limiting the value of D3 to 0.25·D2 or less, the amount of buffering member 30 can be reduced, improving the energy density of the battery cell 7 and improving the cycle characteristics of the electrode assembly 10.

[0109] In some embodiments, the buffer member 30 has a flat plate structure. The flat plate structure is easy to mold and can improve the uniformity of the external force distribution of the electrode assembly 10 when the electrode assembly 10 expands.

[0110] In some embodiments, the cushioning member 30 may be rectangular, circular, elliptical, or have other shapes. Selectively, the cushioning member 30 is a rectangular plate.

[0111] In some embodiments, the buffer member 30 is assembled to the electrode assembly 10.

[0112] "To assemble" means that the cushioning member 30 is connected to the surface of the electrode assembly 10 in close contact. For example, the cushioning member 30 may be attached to the electrode assembly 10 with an adhesive.

[0113] The cushioning member 30, which is assembled to the electrode assembly 10, can be placed inside the housing 21 together with the electrode assembly 10 to simplify the assembly process. The electrode assembly 10 can also limit the vibration of the cushioning member 30 when the battery cell 7 is subjected to an external shock, thereby reducing the risk of displacement of the cushioning member 30.

[0114] In some embodiments, the compressibility f of the buffer member 30 at a pressure of 2 MPa satisfies 1% ≤ f ≤ 99%. Selectively, the compressibility f of the buffer member 30 at a pressure of 2 MPa satisfies 40% ≤ f ≤ 99%.

[0115] In some embodiments, the electrode assembly 10 includes a flat region 10a and two bent regions 10b, the two bent regions 10b each located on either side of the flat region 10a in a third direction Z, and the third direction Z is perpendicular to the first direction X. The size of the buffer member 30 in the third direction Z is L1, the size of the electrode assembly 10 along the third direction Z in a fully charged state is L2, and the size of one electrode assembly 10 along the first direction X in a fully charged state is D4. L1, L2, and D4 satisfy L1 ≥ 0.85(L2 - D4).

[0116] The flat region 10a is a region of the electrode assembly 10 that has a flat structure, and the portion of the electrode sheet in the flat region 10a is in a nearly flat state. The bent region 10b is a region of the electrode assembly 10 that has a bent structure, and the portion of the electrode sheet in the bent region 10b is in a nearly bent state. Exemplarily, the portion of the electrode sheet in the bent region 10b is bent to be nearly arc-shaped.

[0117] In a fully charged state, the size of the bent region 10b along the third direction Z is approximately half of D4, and L2-D4 is approximately equal to the size of the flat region 10a along the third direction Z.

[0118] Because the gap between the bent region 10b and the first side wall 211 of the electrode assembly 10 is large, the expansion force due to the bent region 10b is small. Because the gap between the flat region 10a and the first side wall 211 of the electrode assembly 10 is small, the expansion force due to the flat region 10a is large. In this embodiment, by limiting the value of L1 to 0.85 (L2-D4) or higher, more than 85% of the expansion of the region of the flat region 10a in the third direction Z is absorbed by the buffer member 30, and the cycle characteristics of the flat region 10a are ensured.

[0119] In some embodiments, in the third direction Z, both ends of the buffer member 30 extend beyond the flat region 10a. The buffer member 30 can effectively absorb the expansion of the flat region 10a and improve the cycle characteristics of the flat region 10a.

[0120] In some embodiments, L1 and L2 satisfy L1 ≤ 1.1·L2. In the third direction Z, the portion of the buffer member 30 that exceeds the electrode assembly 10 does not absorb the expansion of the electrode assembly 10, but this leads to an increase in the volume and weight of the buffer member 30. In this embodiment, by setting the value of L1 to 1.1·L2 or less, the amount of buffer member 30 is reduced, and the energy density of the battery cell 7 is improved.

[0121] In some embodiments, the area of ​​the projection of the buffer member 30 onto the inner surface of the first side wall 211 in a first direction X is S1, the area of ​​the inner surface of the first side wall 211 is S2, and S1 and S2 satisfy S1 ≤ 0.95·S2.

[0122] The inner surface of the first side wall 211 compresses the electrode assembly 10 when it expands, suppressing the expansion deformation of the electrode assembly 10. The shell 20 needs to house other functional components besides the electrode assembly 10, and therefore, a portion of the inner surface of the first side wall 211 does not compress the electrode assembly 10. In the embodiment of the present application, S1 ≤ 0.95·S2 reduces the total amount of buffer material 30 used, providing more space for other components within the shell 20, improving the energy density of the battery cell 7 and extending its service life.

[0123] In some embodiments, the size of each cushioning member 30 in the uncompressed state along the first direction X is D5, where D5 satisfies 0.1 mm ≤ D5 ≤ 10 mm. Selectively, the value of D5 is 0.1 mm, 0.5 mm, 1 mm, 2 mm, 4 mm, 5 mm, 8 mm, or 10 mm.

[0124] If D5 is too small, many cushioning members 30 must be placed inside the battery cell 7 to meet the needs, resulting in a more complex structure and reduced assembly efficiency for the battery cell 7. Therefore, in the embodiments of the present invention, the value of D5 is limited to 0.1 mm or more.

[0125] If D5 is too large, the weight of the buffer member 30 becomes too large, occupying too much space, and as a result, the energy density of the battery cell 7 decreases. Therefore, in the embodiments of the present invention, the value of D5 is limited to 10 mm or less.

[0126] In some embodiments, D5 satisfies the condition 0.5 mm ≤ D5 ≤ 4 mm.

[0127] Figure 7 is a schematic cross-sectional view of a battery cell according to some embodiments of the present application, and Figure 8 is a schematic partial cross-sectional view of an electrode assembly and a buffer member of a battery cell according to some embodiments of the present application.

[0128] As shown in Figures 7 and 8, in some embodiments, the electrode assembly 10 includes a first electrode sheet 11, which includes a first body 111 and a first tab 15 extending from one end of the first body 111 along a second direction Y, where the second direction Y is perpendicular to the first direction X. The size of the buffer member 30 along the second direction Y is H1, and the first body 111 is provided with a first active material layer 112, the size of the first active material layer 112 along the second direction Y is H2. H1 and H2 satisfy H1 ≥ 0.85·H2.

[0129] The main reason for the expansion of the electrode assembly 10 is the expansion of the active material layer during the charging process. In the embodiment of the present invention, by limiting the value of H1 to 0.85·H2 or higher, more than 85% of the expansion of the region of the first active material layer 112 in the second direction Y is absorbed by the buffer member 30, reducing the pressure on the first active material layer 112 and improving the cycle characteristics of the electrode assembly 10.

[0130] The first electrode sheet 11 may be a positive electrode sheet or a negative electrode sheet. For example, the first electrode sheet 11 is a negative electrode sheet, and the first active material layer 112 is a negative electrode active material layer. The first body 111 further includes a negative electrode coating region of the negative electrode current collector.

[0131] In some embodiments, the first active material layer 112 includes a base region 112a and a thin-walled region 112b connected to the base region 112a, wherein the thickness of the thin-walled region 112b is less than the thickness of the base region 112a. In the second direction Y, the thin-walled region 112b is located on the side of the base region 112a closer to the first tab 15. In the second direction Y, both ends of the buffer member 30 extend beyond the base region 112a.

[0132] When forming the first pole sheet 11, it is necessary to increase the compression density of the first active material layer 112 by roll pressing the first active material layer 112. In the embodiment of the present invention, the thickness of the thin-walled region 112b is reduced in order to reduce stress concentration at the boundary between the first body 111 and the first tab 15 during the roll pressing process and to reduce the risk of cracking of the first tab 15.

[0133] Since the base region 112a generates a greater expansion force during expansion than the thin-walled region 112b, in the embodiment of this application, both ends of the buffer member 30 in the second direction Y extend beyond the base region 112a, thereby effectively absorbing the expansion of the base region 112a and improving the cycle characteristics of the electrode assembly 10.

[0134] In some embodiments, the electrode assembly 10 further includes a separator 13, and the separator 13 and the first body 111 are arranged in a stack. The size of the separator 13 along the second direction Y is H3, and H1 and H3 satisfy H1 ≤ 1.1·H3.

[0135] The separator 13 provides insulating isolation between the first body 111 and the second electrode sheet 12.

[0136] In the second direction Y, the portion of the buffer member 30 beyond the separator 13 does not absorb the expansion of the electrode assembly 10, but this leads to an increase in the volume and weight of the buffer member 30. In this embodiment, by setting the value of H1 to 1.1·H3 or less, the amount of buffer member 30 used is reduced, and the energy density of the battery cell 7 is improved.

[0137] In some embodiments, in the second direction Y, neither end of the buffer member 30 extends beyond the separator 13, thereby reducing the amount of buffer member 30 used, lowering the risk of the buffer member 30 interfering with other components, and improving the energy density of the battery cell 7.

[0138] Figure 9 is a schematic diagram of the structure of a battery cell according to some other embodiments of the present application.

[0139] As shown in Figure 9, in some embodiments, there are multiple electrode assemblies 10. A buffer member 30 is provided between at least two adjacent electrode assemblies 10.

[0140] By providing the cushioning member 30 between two adjacent electrode assemblies 10, the risk of vibration of the cushioning member 30 when the battery cell 7 is subjected to an external impact can be reduced.

[0141] Figure 10 is a schematic diagram of the structure of a battery cell according to some other embodiments of the present invention. As shown in Figure 10, in some embodiments, there are multiple electrode assemblies 10 and multiple buffer members 30.

[0142] Exemplary, there are two electrode assemblies 10 and two buffer members 30. The two electrode assemblies 10 are arranged adjacent to each other to form an electrode unit, and the two buffer members 30 are located on either side of the electrode unit in the first direction X.

[0143] Figure 11 is a schematic diagram of the structure of a battery cell according to some further embodiments of the present application. As shown in Figure 11, in some embodiments, there are four electrode assemblies 10 and two buffer members 30. The four electrode assemblies 10 are arranged adjacent to each other and constitute an electrode unit, and the two buffer members 30 are located on either side of the electrode unit in the first direction X.

[0144] According to some embodiments of the present application, the present application also provides a battery comprising a battery cell relating to any one of the above embodiments.

[0145] According to some embodiments of the present application, the present application also provides a power consumption device comprising a battery cell according to any one of the above embodiments, the battery cell supplying electrical energy to the power consumption device.

[0146] According to some embodiments of the present application, with reference to Figure 10, the battery cell 7 of the embodiment of the present application includes a shell 20, two electrode assemblies 10, and two buffer members 30. The shell 20 includes two first side walls 211 positioned opposite each other in a first direction X, with the distance between the two first side walls 211 in the first direction X being D1. The two electrode assemblies 10 are housed within the shell 20, and in a fully charged state, the sum of the sizes of the two electrode assemblies 10 along the first direction X is D2. The two electrode assemblies 10 constitute an electrode unit, and the two buffer members 30 are located on either side of the electrode unit in the first direction X. The buffer members 30 are configured to be compressible, with the size of each buffer member 30 in the uncompressed state along the first direction X being D5, and the sum of the sizes of the two buffer members 30 in the uncompressed state along the first direction X being D3. D1, D2, and D3 satisfy 0.9 ≤ (D2 + D3) / D1 ≤ 1.5.

[0147] Figure 12 is a schematic diagram of the flow of a manufacturing method for a battery cell according to some embodiments of the present application.

[0148] As shown in Figure 12, an embodiment of the present application is Step S100 provides a shell including two first side walls arranged opposite to each other along a first direction, Step S200 provides an electrode assembly and a buffer member, The present invention provides a method for manufacturing a battery cell, which includes step S300 of mounting an electrode assembly and a buffer member inside a shell.

[0149] The distance between the two first sidewalls along the first direction is D1. There are M electrode assemblies, where M is a positive integer greater than 0. In a fully charged state, the sum of the sizes of the M electrode assemblies along the first direction is D2. There are N buffer members, where N is a positive integer greater than 0, and the N buffer members and M electrode assemblies are stacked along the first direction. The buffer members are configured to be compressible, and the sum of the sizes of the N buffer members along the first direction in an uncompressed state is D3. D1, D2, and D3 satisfy 0.9 ≤ (D2 + D3) / D1 ≤ 1.5.

[0150] Furthermore, the related structures of the battery cells manufactured by the above-described battery cell manufacturing method can be referenced from the battery cells according to each of the above embodiments.

[0151] When manufacturing a battery cell using the battery cell manufacturing method described above, it is not necessary to follow the steps described above. In other words, the steps may be performed in the order described in the examples, in a different order from the order described in the examples, or several steps may be performed simultaneously. For example, there is no specific order in which steps S100 and S200 are performed, and they can also be performed simultaneously.

[0152] Figure 13 is a schematic block diagram of a battery cell manufacturing system according to some embodiments of the present application.

[0153] As shown in Figure 13, an embodiment of the present invention provides a battery cell manufacturing system 90, comprising a first supplying device 91, a second supplying device 92, and an assembly device 93. The first supplying device 91 is used to provide a shell including two first side walls arranged opposite each other along a first direction. The second supplying device 92 is used to provide electrode assemblies and buffer members. The assembly device 93 is used to mount the electrode assemblies and buffer members within the shell. The distance between the two first side walls in the first direction is D1. There are M electrode assemblies, where M is a positive integer greater than 0. In a fully charged state, the sum of the sizes of the M electrode assemblies along the first direction is D2. There are N buffer members, where N is a positive integer greater than 0, and the N buffer members and M electrode assemblies are stacked along the first direction. The buffer members are configured to be compressible, and the sum of the sizes of the N buffer members in an uncompressed state along the first direction is D3. D1, D2, and D3 satisfy 0.9 ≤ (D2 + D3) / D1 ≤ 1.5.

[0154] The present application will be further described below with reference to the examples.

[0155] To further clarify the purpose of the present invention, the proposed technical solution, and the beneficial technical effects, the present application will be described in more detail below with reference to examples. However, it should be understood that the examples of the present application are for interpretation purposes only and not to limit the present application, and that the examples of the present application are not limited to those described in the specification. Examples for which specific experimental or operating conditions are not described are manufactured under normal conditions or under conditions recommended by the material supplier.

[0156] Example 1 may be manufactured by the following steps.

[0157] (i) The positive electrode active material NCM523, the conductive agent acetylene black, and the adhesive PVDF were mixed in a mass ratio of 96:2:2, the solvent NMP was added, and the mixture was stirred with a vacuum mixer until the system was homogeneous to obtain a positive electrode slurry. The positive electrode slurry was uniformly applied to aluminum foil, dried at room temperature, then transferred to an oven for further drying, and then cold-rolled, slit, and cut to obtain a positive electrode sheet.

[0158] (ii) The negative electrode active material, graphite or a mixture of graphite and other active materials in various mass ratios, the conductive agent acetylene black, the thickener CMC, and the adhesive SBR were mixed in a mass ratio of 96.4:1:1.2:1.4, deionized water was added as the solvent, and the mixture was stirred with a vacuum mixer until the system was homogeneous to obtain a negative electrode slurry. The negative electrode slurry was uniformly applied to copper foil, dried at room temperature, then transferred to an oven for further drying, and then cold-rolled, slit, and cut to obtain a negative electrode sheet.

[0159] (iii) Ethylene carbonate (EC), methyl ethyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, a thoroughly dried lithium salt LiPF6 was dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0160] (iv) A 12 μm thick polypropylene film was used as a separator.

[0161] (v) The electrode assembly was manufactured by laminating a positive electrode sheet, a separator, and a negative electrode sheet, winding the laminated material multiple times, and then pressing it into a flat shape.

[0162] (vi) Two electrode assemblies and two buffer members were stacked and mounted inside the housing, then the end cover and housing were welded together, and processes such as liquid injection, standing, formation, and shaping were performed to obtain a battery cell.

[0163] In step (vi), as shown in Figure 14, the two buffer members 30 and the two electrode assemblies 10 are stacked along the first direction X, and the housing 21 includes two first side walls 211 that are positioned opposite each other in the first direction X. The distance D1 between the two first side walls 211 in the first direction X was measured with a caliper and was found to be 27 mm. Before attaching the buffer members 30 to the housing 21, the thickness D5 of the buffer members 30 was measured with a caliper and was found to be 0.45 mm. In this case, if D3 is the sum of the sizes of the two buffer members 30 in the uncompressed state along the first direction X, then D3 was 0.9 mm.

[0164] Interface detection and cycle characteristic detection were performed on the two battery cells 7 manufactured using the above manufacturing steps.

[0165] Interface detection At room temperature, one battery cell 7 was fully charged at a rate of 0.33C. Once the battery cell 7 was fully charged, it was disassembled, and the size of each electrode assembly 10 along the first direction X in the fully charged state was measured with calipers. After the size measurements were completed, the electrode assembly 10 was further disassembled, and the interface state of the negative electrode sheet was observed.

[0166] Based on measurements and calculations, the sum of the sizes D2 of the two electrode assemblies 10 along the first direction X was 25.6 mm.

[0167] Detection of cycle characteristics Another battery cell 7 was fixed to the jig, and the two first side walls 211 of the battery cell 7 were clamped from both sides by the jig, applying a clamping force of 3000N to the first side walls 211. The jig is equipped with a press force sensor to detect the press force F between the first side walls 211 and the jig in real time.

[0168] Under normal temperature conditions, battery cell 7 was charged and discharged at a 1C rate until its capacity decreased to 90% of its initial capacity, completing a full charge-discharge cycle test.

[0169] During the cycle process, the state of battery cell 7 was monitored in real time. When the capacity of battery cell 7 decreased to 90% of its initial capacity, the number of cycles of battery cell 7 was recorded, and the increase in the expansion force ΔF of battery cell 7 was calculated using the formula ΔF = F - 3000N.

[0170] Exemplary, the jig may include two clamping plates that clamp the battery cell 7 from both sides, each facing two first side walls 211, and a buffer pad may be provided between the clamping plates and the corresponding first side walls 211.

[0171] Example 2: The manufacturing method and detection method for the battery cell in Example 2 are the same as in Example 1, except that D3 is 1.4 mm.

[0172] Example 3: The manufacturing method and detection method for the battery cell in Example 3 are the same as in Example 1, except that D3 is 4.1 mm.

[0173] Example 4: The manufacturing method and detection method for the battery cell in Example 4 refer to Example 1, but differ in that D3 is 8.15 mm.

[0174] Example 5: The manufacturing method and detection method for the battery cell in Example 5 refer to Example 1, but differ in that D3 is 12.2 mm.

[0175] Example 6: The manufacturing method and detection method for the battery cell in Example 6 refer to Example 1, but differ in that D3 is 14.9 mm.

[0176] Example 7: The manufacturing method and detection method for the battery cell in Example 7 are the same as in Example 1, but differ in that D3 is 0.7 mm and D2 is 23.6 mm.

[0177] Example 8: The manufacturing method and detection method for the battery cell in Example 8 are the same as in Example 1, but differ in that D3 is 2.1 mm and D2 is 23.6 mm.

[0178] Comparative Example 1: The manufacturing method and detection method for the battery cell of Comparative Example 1 refer to Example 1, but differ in that D2 is 24.3 mm and no buffer material is provided inside Comparative Example 1 (i.e., D3 is 0).

[0179] Comparative Example 2: The manufacturing method and detection method for the battery cell in Comparative Example 2 refer to Example 1, but differ in that D2 is 25.6 mm and no buffer material is provided inside Comparative Example 2 (i.e., D3 is 0).

[0180] Comparative Example 3: The manufacturing method and detection method for the battery cell in Comparative Example 3 refer to Example 1, but differ in that D2 is 26.4 mm and no buffer material is provided inside Comparative Example 3 (i.e., D3 is 0).

[0181] Comparative Example 4: The manufacturing method and detection method for the battery cell in Comparative Example 4 are the same as those in Example 1, except that D3 is 0.6 mm and D2 is 21 mm.

[0182] Comparative Example 5: The manufacturing method and detection method for the battery cell in Comparative Example 5 are the same as those in Example 1, except that D3 is 17.6 mm.

[0183] Table 1 shows the evaluation results for Examples 1-8 and Comparative Examples 1-5.

[0184] [Table 1]

[0185] Furthermore, in the axial direction of the electrode assembly's winding, if the ratio of wrinkle size to electrode sheet size is less than 5%, it is considered wrinkle-free; if the ratio is between 5% and 30%, it is considered slight wrinkles; and if the ratio exceeds 30%, it is considered severe wrinkles.

[0186] Referring to Examples 1 to 8 and Comparative Examples 1 to 3, the embodiments of the present application provide a buffering member which reduces the risk of wrinkles forming on the electrode sheet when the battery cell is first charged, reduces the expansion force generated in the battery cell during the cycle, increases the number of cycles of the battery cell, and improves the cycle characteristics of the battery cell.

[0187] Referring to Examples 1-8 and Comparative Examples 4-5, the embodiments of the present application limit the value of (D2+D3) / D1 to between 0.9 and 1.5, thereby reducing the risk of wrinkles forming on the electrode sheet when the battery cell is first charged, reducing the expansion force generated in the battery cell during the cycle, increasing the number of cycles of the battery cell, and improving the cycle characteristics of the battery cell.

[0188] Although this application has been described with reference to preferred embodiments, various improvements may be made without departing from the scope of this application, and components therein may be replaced with equivalents, and in particular, each technical feature mentioned in each embodiment may be combined in any way, provided that there is no structural inconsistency. This application is not limited to the specific embodiments disclosed herein, but includes all technical ideas within the claims. [Explanation of Symbols]

[0189] The reference numerals in the drawings of specific embodiments are as follows: 1 vehicle 2 batteries 3 Controllers 4 motors 5 box body 5a 1st box part 5b 2nd box part 5c storage space 6 Battery Modules 7 Battery cells 10 Electrode Assembly 11 First pole sheet 111 Main body 112 First active material layer 112a Base region 112b Thin area 12 Second pole sheet 13 Separator 14 Main body 15 Tab 1 16. Tab 2 10a Flat area 10b Bend area 20 shells 21 Housing 211 First side wall 212 Second side wall 22 End cover 30 Cushioning material 40 electrode terminal 90 Manufacturing Systems 91 First providing device 92 Second providing device 93 Assembly equipment X 1st direction Y Second direction Z 3rd direction

Claims

1. A battery cell comprising a shell, M electrode assemblies, and N buffer members, The shell includes two first side walls arranged opposite to each other along a first direction, and the distance between the two first side walls along the first direction is D1. The M electrode assemblies are housed within the shell, and in a fully charged state, the sum of the sizes of the M electrode assemblies along the first direction is D2, and M is a positive integer greater than 0. The N buffer members are housed within the shell and stacked with the M electrode assemblies along the first direction, and the buffer members are flat plate structures configured to be compressible, the sum of the sizes of the N buffer members along the first direction in their uncompressed state is D3, and N is a positive integer greater than 0. D1, D2, and D3 satisfy 0.9 ≤ (D2 + D3) / D1 ≤ 1.5, D2 and D3 satisfy D3 ≤ 0.25 * D2. Battery cell.

2. D1, D2, and D3 satisfy 0.98 ≤ (D2 + D3) / D1 ≤ 1.

25. The battery cell according to claim 1.

3. The first direction is parallel to the thickness direction of the battery cell. The battery cell according to claim 1.

4. A battery cell comprising a shell, M electrode assemblies, and N buffer members, The shell includes two first side walls arranged opposite to each other along a first direction, and the distance between the two first side walls along the first direction is D1. The M electrode assemblies are housed within the shell, and in a fully charged state, the sum of the sizes of the M electrode assemblies along the first direction is D2, and M is a positive integer greater than 0. The N buffer members are housed within the shell and stacked with the M electrode assemblies along the first direction, and the buffer members are flat plate structures configured to be compressible, the sum of the sizes of the N buffer members along the first direction in their uncompressed state is D3, and N is a positive integer greater than 0. D1, D2, and D3 satisfy 0.9 ≤ (D2 + D3) / D1 ≤ 1.5, The electrode assembly includes a first electrode sheet, the first electrode sheet includes a first body and a first tab drawn out from one end along a second direction from the first body, the second direction being perpendicular to the first direction. The size of the buffer member along the second direction is H1, and the first active material layer is provided on the first body, and the size of the first active material layer along the second direction is H2. H1 and H2 satisfy H1 ≥ 0.85 * H2. Battery cell.

5. The first active material layer includes a base region and a thin-walled region connected to the base region, wherein the thickness of the thin-walled region is less than the thickness of the base region. In the second direction, the thin-walled region is located on the side of the base region closer to the first tab, In the second direction, both ends of the buffer member extend beyond the base region. The battery cell according to claim 4.

6. The electrode assembly further includes a separator, and the separator and the first body are arranged in a stacked manner. The size of the separator along the second direction is H3. H1 and H3 satisfy H1 ≤ 1.1・H3. The battery cell according to claim 4.

7. In the second direction, neither end of the buffer member extends beyond the separator. The battery cell according to claim 6.

8. A battery cell comprising a shell, M electrode assemblies, and N buffer members, The shell includes two first side walls arranged opposite to each other along a first direction, and the distance between the two first side walls along the first direction is D1. The M electrode assemblies are housed within the shell, and in a fully charged state, the sum of the sizes of the M electrode assemblies along the first direction is D2, and M is a positive integer greater than 0. The N buffer members are housed within the shell and stacked with the M electrode assemblies along the first direction, and the buffer members are flat plate structures configured to be compressible, the sum of the sizes of the N buffer members along the first direction in their uncompressed state is D3, and N is a positive integer greater than 0. D1, D2, and D3 satisfy 0.9 ≤ (D2 + D3) / D1 ≤ 1.5, The electrode assembly includes a flat region and two bent regions, the two bent regions each located on either side of the flat region along a third direction, and the third direction is It is perpendicular to the first direction, The size of the buffer member along the third direction is L1, the size of the electrode assembly along the third direction in a fully charged state is L2, and the size of one electrode assembly along the first direction in a fully charged state is D4. L1, L2, and D4 satisfy L1 ≥ 0.85(L2 - D4). Battery cell.

9. In the third direction, both ends of the buffer member extend beyond the flat region. The battery cell according to claim 8.

10. L1 and L2 satisfy L1 ≤ 1.1・L2. The battery cell according to claim 8.

11. A battery cell comprising a shell, M electrode assemblies, and N buffer members, The shell includes two first side walls arranged opposite to each other along a first direction, and the distance between the two first side walls along the first direction is D1. The M electrode assemblies are housed within the shell, and in a fully charged state, the sum of the sizes of the M electrode assemblies along the first direction is D2, and M is a positive integer greater than 0. The N buffer members are housed within the shell and stacked with the M electrode assemblies along the first direction, and the buffer members are flat plate structures configured to be compressible, the sum of the sizes of the N buffer members along the first direction in their uncompressed state is D3, and N is a positive integer greater than 0. D1, D2, and D3 satisfy 0.9 ≤ (D2 + D3) / D1 ≤ 1.5, The area of ​​the projection of the buffer member onto the inner surface of the first side wall along the first direction is S1, the area of ​​the inner surface of the first side wall is S2, and S1 and S2 satisfy S1 ≤ 0.95 * S2. Battery cell.

12. A battery cell comprising a shell, M electrode assemblies, and N buffer members, The shell includes two first side walls arranged opposite to each other along a first direction, and the distance between the two first side walls along the first direction is D1. The M electrode assemblies are housed within the shell, and in a fully charged state, the sum of the sizes of the M electrode assemblies along the first direction is D2, and M is a positive integer greater than 0. The N buffer members are housed within the shell and stacked with the M electrode assemblies along the first direction, and the buffer members are flat plate structures configured to be compressible, the sum of the sizes of the N buffer members along the first direction in their uncompressed state is D3, and N is a positive integer greater than 0. D1, D2, and D3 satisfy 0.9 ≤ (D2 + D3) / D1 ≤ 1.5, The size of each cushioning member in the uncompressed state along the first direction is D5, and D5 satisfies 0.1 mm ≤ D5 ≤ 10 mm. Battery cell.

13. A battery cell comprising a shell, M electrode assemblies, and N buffer members, The shell includes two first side walls arranged opposite to each other along a first direction, and the distance between the two first side walls along the first direction is D1. The M electrode assemblies are housed within the shell, and in a fully charged state, the sum of the sizes of the M electrode assemblies along the first direction is D2, and M is a positive integer greater than 0. The N buffer members are housed within the shell and stacked with the M electrode assemblies along the first direction, and the buffer members are flat plate structures configured to be compressible, the sum of the sizes of the N buffer members along the first direction in their uncompressed state is D3, and N is a positive integer greater than 0. D1, D2, and D3 satisfy 0.9 ≤ (D2 + D3) / D1 ≤ 1.5, D2 and D3 satisfy D3 ≤ 0.25 * D2, The compressibility f of the cushioning member at a pressure of 2 MPa satisfies 1% ≤ f ≤ 99%. Battery cell.

14. A battery cell comprising a shell, M electrode assemblies, and N buffer members, The shell includes two first side walls arranged opposite to each other along a first direction, and the distance between the two first side walls along the first direction is D1. The M electrode assemblies are housed within the shell, and in a fully charged state, the sum of the sizes of the M electrode assemblies along the first direction is D2, and M is a positive integer greater than 0. The N buffer members are housed within the shell and stacked with the M electrode assemblies along the first direction, and the buffer members are flat plate structures configured to be compressible, the sum of the sizes of the N buffer members along the first direction in their uncompressed state is D3, and N is a positive integer greater than 0. D1, D2, and D3 satisfy 0.9 ≤ (D2 + D3) / D1 ≤ 1.5, The buffer member is assembled to the electrode assembly. Battery cell.

15. A battery cell comprising a shell, M electrode assemblies, and N buffer members, The shell includes two first side walls arranged opposite to each other along a first direction, and the distance between the two first side walls along the first direction is D1. The M electrode assemblies are housed within the shell, and in a fully charged state, the sum of the sizes of the M electrode assemblies along the first direction is D2, and M is a positive integer greater than 0. The N buffer members are housed within the shell and stacked with the M electrode assemblies along the first direction, and the buffer members are flat plate structures configured to be compressible, the sum of the sizes of the N buffer members along the first direction in their uncompressed state is D3, and N is a positive integer greater than 0. D1, D2, and D3 satisfy 0.9 ≤ (D2 + D3) / D1 ≤ 1.5, D2 and D3 satisfy D3 ≤ 0.25 * D2, The electrode assemblies are multiple in number, The buffer member is provided between at least two adjacent electrode assemblies. Battery cell.

16. A plurality of battery cells according to any one of claims 1 to 15, battery.

17. A power consumption device, The battery cell comprises the battery cell described in any one of claims 1 to 15, wherein the battery cell is used to supply electrical energy. Power consuming device.

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