Battery cells, batteries, and power consuming 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 priority to Chinese patent application No. 202210379965.0, entitled "Battery Cell, Battery, and Power Consumption Device," filed on April 12, 2022, the entire contents of which are incorporated herein by reference.

[0002] TECHNICAL FIELD This application relates to the field of batteries, and in particular to battery cells, batteries, and power consuming devices. [Background technology]

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

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

[0005] The present application provides a battery cell capable of improving the cycle characteristics of the battery cell, a manufacturing method and manufacturing system thereof, a battery, and a power consuming device.

[0006] In a first aspect, the present application provides a battery cell including 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.

[0007] In the above technical solution, the buffer member can limit the deformation of the electrode assembly to a certain 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 the electrode sheet of the electrode assembly, and extend the service life of the electrode assembly. During the cycle of the battery cell, the buffer member is compressed when pressed by the electrode assembly, providing space for the expansion of the electrode assembly, reducing the acting force between the shell and the electrode assembly, and improving the cycle characteristics of the electrode assembly. The above technical solution can reduce the risk of wrinkling the electrode sheet, reduce the amount of buffer member 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 by limiting the value of (D2+D3) / D1 to 0.9-1.5.

[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 solutions 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, the first electrode sheet including a first body and a first tab extending from one end of the first body along a second direction, the second direction being perpendicular to the first direction. The buffer member has a size along the second direction of H1, a first active material layer is provided on the first body, and the first active material layer has a size along the second direction of 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 charging. In the above technical solution, by limiting the value of H1 to 0.85·H2 or more, 85% or more of the expansion of the area of ​​the first active material layer in the second direction is absorbed by the buffer material, reducing the pressure received by 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 thinned region connected to the base region, the thinned region having a thickness less than a thickness of the base region. The thinned region is located on a side of the base region closer to the first tab in the second direction. Both ends of the cushioning member extend beyond the base region in the second direction.

[0014] Since the expansion force generated when the base region expands is greater than that generated when the thin-walled region expands, in the above technical solution, both ends of the buffer member in the second direction exceed the base region, thereby effectively absorbing the expansion of the base region and 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 laminated. The separator has a size along the second direction of H3. H1 and H3 satisfy H1≦1.1·H3. In the second direction, the portion of the buffer material 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 solution, the value of H1 is set to 1.1·H3 or less, thereby reducing the amount of buffer material used and improving the energy density of the battery cell.

[0016] In some embodiments, neither end of the cushioning member exceeds the separator in the second direction, thereby reducing the amount of cushioning member used, reducing the risk of the cushioning member interfering with other components, and improving 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 being located on either side of the flat region along a third direction, and the third direction being perpendicular to the first direction. The buffer member has a size along the third direction of L1, the electrode assembly has a size along the third direction in a fully charged state of L2, and the electrode assembly has a size along the first direction in a fully charged state of D4. L1, L2, and D4 satisfy L1≧0.85(L2-D4).

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

[0019] In some embodiments, both ends of the cushioning member exceed the flat region in the third direction, and the cushioning 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 exceeds 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, the value of L1 is set to 1.1·L2 or less, thereby reducing the amount of the buffer member and improving the energy density of the battery cell.

[0021] In some embodiments, the area of ​​the projection of the cushioning member on the inner surface of the first side wall 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 technical solution can reduce the overall usage of the buffer material, increase the space for other components in the shell, and improve the energy density and service life of the battery cell.

[0023] In some embodiments, the size of each cushioning member in the first direction in an uncompressed state is D5, and D5 satisfies 0.1 mm≦D5≦10 mm.

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

[0025] In some embodiments, the buffer member is assembled to the electrode assembly. The buffer member assembled to the electrode assembly can be housed together with the electrode assembly, thereby simplifying the assembly process. The electrode assembly can also suppress the shaking of the buffer member when the battery cell receives an external impact, thereby reducing the risk of the buffer member being displaced.

[0026] In some embodiments, the electrode assembly is a plurality of electrode assemblies. A buffer member is provided between at least two adjacent electrode assemblies. By providing the buffer member between the two adjacent electrode assemblies, the risk of the buffer member shaking when the battery cell receives an external impact can be reduced.

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

[0028] In a second aspect, the present application provides a battery comprising a battery cell according to any one of the embodiments of the first aspect.

[0029] In a third aspect, embodiments of the present application provide a power consumption device, the power consumption device comprising a battery cell according to any one of the embodiments of the first aspect, the battery cell being adapted to supply electrical energy.

[0030] In a fourth aspect, an embodiment of the present application provides a method for manufacturing a battery cell, the method including the steps of: providing a shell including two first side walls arranged opposite to each other along a first direction; providing an electrode assembly and a buffer member; and placing the electrode assembly and the buffer member in 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. 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 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.

[0031] In a fifth aspect, an embodiment of the present application provides a battery cell manufacturing system including a first providing device, a second providing device, and an assembly device. The first providing device is used to provide a shell including two first side walls arranged opposite to each other along a first direction. The second providing device is used to provide an electrode assembly and a buffer member. The assembly device is used to attach the electrode assembly and the buffer member into the shell. The distance between the two first side walls along the first direction is D1. M electrode assemblies are provided, M being a positive integer greater than 0, and a sum of the sizes of the M electrode assemblies along the first direction in a fully charged state is D2. N buffer members are provided, N being a positive integer greater than 0, the N buffer members and the M electrode assemblies are stacked along the first direction, the buffer members are configured to be compressible, and a 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 description of the drawings]

[0032] Features, advantages, and technical effects of exemplary embodiments of the present application are described below with reference to the drawings. [Figure 1] 1 is a structural schematic diagram of a vehicle according to some embodiments of the present application. [Diagram 2] FIG. 2 is a schematic disassembly diagram of a battery according to some embodiments of the present application. [Diagram 3] FIG. 3 is a schematic disassembled view of the battery module shown in FIG. 2. [Figure 4] FIG. 2 is an exploded schematic diagram of a battery cell according to some embodiments of the present application. [Diagram 5] 1 is a structural schematic diagram of a battery cell according to some embodiments of the present application. FIG. [Figure 6] FIG. 2 is a cross-sectional schematic diagram of an electrode assembly of a battery cell according to some embodiments of the present application. [Figure 7] FIG. 1 is a schematic cross-sectional view of a battery cell according to some embodiments of the present application. [Figure 8] FIG. 2 is a partial cross-sectional schematic view of an electrode assembly and a buffer member of a battery cell according to some embodiments of the present application. [Figure 9] 3A to 3C are structural schematic diagrams of battery cells according to some other embodiments of the present application. [Figure 10] 4A to 4C are schematic structural diagrams of battery cells according to some other embodiments of the present application. [Figure 11] 1 is a structural schematic diagram of a battery cell according to further some embodiments of the present application. FIG. [Figure 12] FIG. 2 is a schematic diagram of a manufacturing method for a battery cell according to some embodiments of the present application. [Figure 13] FIG. 1 is a schematic block diagram of a battery cell manufacturing system in accordance with some embodiments of the present application. [Figure 14] 1 is a structural schematic diagram of a battery cell according to some embodiments of the present application. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are explicitly described below with reference to the drawings of the embodiments of the present application, but it is clear that the described embodiments are only a part of the embodiments of the present application, and are not all of the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without paying creative efforts all belong to the protection scope of the present application.

[0034] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the art. In this application, the terms used in the specification of the application are used only to describe specific embodiments and are not intended to limit the application. The terms "comprise", "comprise" and "have" and their variations in the specification, claims and above description of the drawings of this application are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application and above drawings are intended to distinguish different objects and are not intended to describe a specific order or primary and secondary relationships.

[0035] When an "embodiment" is described in this application, it means that a particular feature, structure, or characteristic described with reference to the embodiment may be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification do not necessarily refer to the same embodiment, or to separate or alternative embodiments that are mutually exclusive of other embodiments.

[0036] In the description of this application, unless otherwise clearly specified and limited, the terms "attach", "connect", "join" and "assemble" should be understood in a broad sense, for example, they may be fixed connection, detachable connection, or integral connection, or may be direct connection, indirect connection via an intermediate medium, or internal communication between two components. For those skilled in the art, the specific meanings of the above terms in this specification can be understood according to the specific situation.

[0037] The term "and / or" in this application merely describes the relation between related objects, and means that there are three relations, for example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the sign " / " in this application generally represents that the related objects before and after it are in an "or" relation.

[0038] In the embodiments of the present application, the same reference numerals represent the same elements, and detailed descriptions of the same elements in different embodiments are omitted for brevity. It should be understood that the dimensions of various elements in the embodiments of the present application, such as thickness, length, width, etc., and the dimensions of the entire integrated device, such as thickness, length, width, etc., shown in the accompanying drawings, are merely illustrative, and the present application should not be construed as limiting in any way.

[0039] As used herein, "plurality" means two or more (including two).

[0040] In the present application, the battery cell may include a lithium ion secondary battery cell, a lithium ion primary battery cell, a lithium sulfur battery cell, a sodium lithium ion battery cell, a sodium ion battery cell, or a magnesium ion battery cell, etc., and the embodiments of the present application are not limited thereto. The shape of the battery cell may be a cylinder, a flat body, a rectangular parallelepiped, or other shape, and the embodiments of the present application are not limited thereto.

[0041] 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. The battery usually includes a housing for packing one or more battery cells. The housing can prevent liquids and other foreign objects from affecting the charging or discharging of the battery cells.

[0042] The battery cell includes an electrode assembly and an electrolyte, and the electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator. The battery cell is mainly operated by the movement of metal ions between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode collector and a positive electrode active material layer, and the positive electrode active material layer is applied to the surface of the positive electrode collector. The positive electrode collector includes a positive electrode application area and a positive electrode tab connected to the positive electrode application area, and the positive electrode active material layer is applied to the positive electrode application area, and the positive electrode tab is not applied to the positive electrode active material layer. Taking a lithium-ion battery cell as an example, the material of the positive electrode collector may be aluminum, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material may be lithium cobalt oxide, lithium iron phosphate, ternary lithium, lithium manganate, etc. The negative electrode sheet includes a negative electrode collector and a negative electrode active material layer, the negative electrode active material layer is applied to the surface of the negative electrode collector, the negative electrode collector includes a negative electrode application area and a negative electrode tab connected to the negative electrode application area, the negative electrode active material layer is applied to the negative electrode application area, and the negative electrode tab is not applied with the negative electrode active material layer. The material of the negative electrode collector may be copper, the negative electrode active material layer includes 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, and a receiving chamber is formed inside the shell to receive the electrode assembly. The shell protects the electrode assembly from the outside and prevents external foreign objects from affecting the charging or discharging of the electrode assembly.

[0044] During the charging process, the electrode assembly expands. The expanded electrode assembly presses the shell, and the shell exerts a reaction force on the electrode assembly, limiting the expansion of the electrode assembly. If the acting force between the electrode assembly and the shell is too large, the electrolyte between the pole sheets will be squeezed out, which may affect the cycle characteristics of the electrode assembly.

[0045] The inventors have attempted to provide a gap between the electrode assembly and the shell, which provides space for the expansion of the electrode assembly, thereby reducing the force acting between the shell and the electrode assembly, and improving the cycle characteristics of the electrode assembly. However, the inventors have found that when the electrode assembly is first charged, the presence of this gap causes the electrode assembly to be not restrained by the shell, or the restraining force by the shell is small, resulting in a decrease in the uniformity of the force experienced by the electrode assembly, and a risk of wrinkling of the electrode sheet. If the electrode sheet is wrinkled, metal ions may precipitate from the electrode sheet during the subsequent cycle process, shortening the cycle life of the electrode assembly, and even causing the electrode assembly to fail.

[0046] In view of this, the present inventors have installed a buffer member in the shell. The buffer member limits the deformation of the electrode assembly to a certain extent when the battery cell is first charged, improves the uniformity of the external force distribution of the electrode assembly, reduces the risk of the electrode sheet of the electrode assembly being wrinkled, and extends the life of the electrode assembly. During the cycle process of the battery cell, the buffer member is compressed when pressed by the electrode assembly, providing space for the expansion of the electrode assembly, reducing the acting force between the shell and the electrode assembly, and improving the cycle characteristics of the electrode assembly. After calculation and testing, the present inventors have determined that the size of the buffer member is set according to the size of the electrode assembly and the size of the shell, thereby improving the cycle characteristics of the electrode assembly.

[0047] The battery cells described in the embodiments of the present application are suitable for use in batteries and power consuming devices that use the battery cells.

[0048] The power consuming device may be a vehicle, a mobile phone, a portable device, a laptop, a ship, a spacecraft, an electric toy, an electric tool, etc. The vehicle may be a fuel vehicle, a gasoline vehicle, or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle, or a range-extending vehicle, etc. The spacecraft may include an aircraft, a rocket, a space shuttle, a spacecraft, etc. The electric toy may include a game console, an electric car toy, an electric ship toy, an electric plane toy, or other stationary or mobile electric toy. The electric tool may include an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a metal cutting power tool such as a concrete vibrator, a planer, a grinding power tool, an assembly power tool, and a railway power tool. The embodiment of the present application does not particularly limit the above power consuming device.

[0049] For convenience of explanation, the following embodiment will be described taking a case where the power consuming device is a vehicle as an example.

[0050] FIG. 1 is a structural schematic diagram of a vehicle according to some embodiments of the present application.

[0051] 1, a battery 2 is provided inside the vehicle 1, and the battery 2 may be provided 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 an operating power source for the vehicle 1.

[0052] The vehicle 1 may further include a controller 3 and a motor 4, where the controller 3 is for controlling the battery 2 to supply power to the motor 4, for example for starting the vehicle 1, navigation and operating power needs during driving.

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

[0054] FIG. 2 is a schematic disassembled view of a battery according to some embodiments of the present application.

[0055] As shown in FIG. 2, the battery 2 includes a case 5 and a battery cell (not shown), and the battery cell is housed within the case 5.

[0056] The box 5 stores the battery cells, and the box 5 may have various structures. In some embodiments, the box 5 may include a first box part 5a and a second box part 5b, and the first box part 5a and the second box part 5b are fitted together, and a storage space 5c for storing the battery cells is defined by both the first box part 5a and the second box part 5b. The second box part 5b may have a hollow structure with one end open, and the first box part 5a has a plate-like structure, and the first box part 5a is fitted to the open side of the second box part 5b to form the box 5 having the storage space 5c. The first box part 5a and the second box part 5b may also have a hollow structure with one end open, and the open side of the first box part 5a is fitted to the open side of the second box part 5b to form the box 5 having the storage space 5c. Of course, the first box portion 5a and the second box portion 5b may have various shapes, such as a cylindrical body or a rectangular parallelepiped.

[0057] In order to improve the sealing performance between the first box body portion 5a and the second box body portion 5b after connection, a sealing member such as a sealant or a seal ring may be provided between the first box body portion 5a and the second box body portion 5b.

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

[0059] The battery 2 may have one or more battery cells. When there are multiple battery cells, the multiple battery cells may be connected in series, parallel, or series-parallel, and a series-parallel connection means that some of the multiple battery cells are connected in series and some are connected in parallel. The multiple battery cells may be directly connected in series, parallel, or series-parallel, and then the multiple battery cells may be integrated and stored in the box 5. Of course, the multiple battery cells may be connected in series, parallel, or series-parallel to form a battery module 6, and then the multiple battery modules 6 may be connected in series, parallel, or series-parallel to form a battery module and stored in the box 5.

[0060] FIG. 3 is a schematic disassembled view of the battery module shown in FIG.

[0061] In some embodiments, there are a plurality of battery cells 7, as shown in Fig. 3. First, a plurality of battery cells 7 are connected in series, in parallel, or in series-parallel to form a battery module 6, and then the plurality of battery modules 6 may be connected in series, in parallel, or in series-parallel to be integrated and housed in a box.

[0062] The plurality of battery cells 7 of the battery module 6 may be electrically connected to each other by bus bar members, so that the plurality of battery cells 7 of the battery module 6 may be connected in parallel, in series, or in a series-parallel configuration.

[0063] Fig. 4 is an exploded schematic diagram of a battery cell according to some embodiments of the present application, Fig. 5 is a structural schematic diagram of a battery cell according to some embodiments of the present application, in which the end cover is omitted, and Fig. 6 is a cross-sectional schematic diagram of an electrode assembly of a battery cell according to some embodiments of the present application.

[0064] As shown in FIGS. 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 arranged opposite to each other in a first direction X, and the distance between the two first side walls 211 in the first direction X is D1. M electrode assemblies 10 are provided, and the M electrode assemblies 10 are housed in the shell 20. 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. N buffer members 30 are provided, and the N buffer members 30 are housed in the shell 20 and stacked together with the M electrode assemblies 10 along the first direction X. The buffer member 30 is configured to be compressible, and the sum of the sizes of the N buffer members 30 along the first direction X in an uncompressed state 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 has a hollow structure, the inside of which serves as a storage chamber for storing the electrode assembly 10 and the 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, when the electrode assembly 10 has a rectangular parallelepiped structure, a rectangular parallelepiped shell can be used.

[0066] In this embodiment, there is no limitation on the material of the shell 20. For example, the shell 20 may be made of a hard material such as aluminum, steel, or plastic, or may be made of an aluminum plastic film, a steel plastic film, or other soft materials.

[0067] The two first side walls 211 are located on both sides of the storage chamber in the first direction X. Illustratively, the size of the storage chamber along the first direction X is D1.

[0068] The value of D1 can be measured in different ways, for example using a vernier caliper or using microscopic markings, 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 operates mainly 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 insulate the first electrode sheet 11 and the second electrode sheet 12.

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

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

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

[0073] When only one electrode assembly 10 is provided inside the battery cell 7, the value of D2 is equal to D4. When 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] When a plurality of electrode assemblies 10 are provided, the size D4 along the first direction X of the different electrode assemblies 10 may be the same or different.

[0075] N is a positive integer greater than 0, that is, the number of the buffer member 30 may be one or more.

[0076] The N buffer members 30 and the M electrode assemblies 10 are stacked along the first direction X. In the embodiment of the present application, the stacking order of the buffer members 30 and the 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. Multiple electrode assemblies 10 may be sequentially provided along the first direction X to configure one 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 sequentially provided along the first direction X to configure one buffer unit, and the electrode assembly 10 may be provided on one side of the buffer unit in the first direction X. Optionally, the electrode assembly 10 may be provided between two adjacent buffer members 30.

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

[0080] When pressed by the electrode assembly 10 , the cushioning member 30 is compressed to provide space for the expansion of the electrode assembly 10 and reduce the acting force between the first side wall 211 and the electrode assembly 10 .

[0081] For example, the buffer member 30 has a certain elastic deformation ability, and is compressed by the electrode assembly 10 when the electrode assembly 10 is fully charged, and recovers at least a part of the deformation when the electrode assembly 10 is fully discharged, thereby ensuring that the buffer member 30 abuts against the electrode assembly 10, improving the uniformity of the external force distribution of the electrode assembly 10, and reducing the risk of wrinkles on the electrode sheet of the electrode assembly 10.

[0082] In the embodiment of the present application, the specific material of the buffer member 30 is not limited, and it is required to have a certain deformation ability and to recover at least a part of the deformation when the external force is removed. Illustratively, when it is necessary to measure the size of each buffer member 30 along the first direction X in an uncompressed state, the battery cell 7 is disassembled to take out the buffer member 30, and then a caliper is used to measure the size D5 of each buffer member 30 along the first direction X in an uncompressed state. Optionally, during the manufacture of the battery cell 7, the size D5 of each buffer member 30 along the first direction X in an uncompressed state is measured before the buffer member 30 is put into the shell.

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

[0084] When a plurality of cushioning members 30 are provided, the size D5 in the first direction X of the different cushioning members 30 in an uncompressed state may be the same or different.

[0085] In the embodiment of the present application, the shape of the cushioning member 30 is not limited, and may be a plate, a block, or other irregular shape.

[0086] The buffer member 30 can to some extent suppress the deformation of the electrode assembly 10 when the battery cell 7 is initially charged, improve the uniformity of the external force distribution of the electrode assembly 10, reduce the risk of wrinkling the electrode sheet of the electrode assembly 10, and extend the service 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 acting force 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 wrinkling the electrode sheet of the electrode assembly 10. Although the buffer member 30 can suppress deformation of the electrode assembly 10 to some extent when the battery cell 7 is initially charged, if the value of (D2+D3) / D1 is too small, the buffer member 30 is unlikely to effectively suppress wrinkling of the electrode sheet. In consideration of this, the inventors set (D2+D3) / D1 to be 0.9 or more, thereby improving the utilization rate of the space and reducing the risk of wrinkling the electrode sheet.

[0088] The larger the value of (D2+D3) / D1, the better the buffer member 30 can suppress the deformation of the electrode assembly 10 when the battery cell 7 is initially charged. Of course, the larger the value of (D2+D3) / D1, the larger the space and weight the buffer member 30 occupies, and the greater the compression amount of the buffer member 30 during the cycle process of the battery cell 7. If the value of (D2+D3) / D1 is too large, the amount of compression of the buffer member 30 inserted into the shell becomes small, the amount of expansion that the buffer member 30 can absorb is insufficient, and the expansion force of the electrode assembly 10 is too large. In consideration of this, the inventors set (D2+D3) / D1 to 1.5 or less, thereby reducing the amount of the buffer member 30 and 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] Alternatively, 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 body portion 14, and a first tab 15 and a second tab 16 extending from the body portion 14. The body portion 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 tab 15 and the second tab 16 is a positive electrode tab, and the other is a negative electrode tab.

[0092] In the present application, the size of the main body 14 in the first direction X in a fully charged state 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 fittingly covers the opening. Illustratively, the housing 21 includes two first side walls 211.

[0094] The housing 21 may have a structure that is open on one side, and one end cover 22 is provided and fitted to the opening of the housing 21. Alternatively, the housing 21 may be configured as a structure that is open on both sides, and two end covers 22 are provided, and the two end covers 22 are fitted to two openings of the housing 21, respectively.

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

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

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

[0098] In some embodiments, the housing 21 includes two second side walls 212, which are disposed opposite each other in a third direction Z. Optionally, 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 provided 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 sidewall 211 and second sidewall 212 are connected via an arc-shaped wall.

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

[0102] During cycling of the battery cell 7, the expansion of the electrode assembly 10 may cause deformation of the first side wall 211. Since the deformation at the end of the first side wall 211 close to the second side wall 212 is small, the value measured by pinching the ends of the two first side walls 211 close to the second side wall 212 with a vernier caliper 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 of the electrode terminals 40 is electrically connected to the first electrode sheet 11 of the electrode assembly 10, and the other of the electrode terminals 40 is electrically connected to the second electrode sheet 12, so that electrical energy from the electrode assembly 10 is extracted to the outside of the shell 20.

[0104] In some embodiments, the buffer member 30 may have a porous structure. The pores 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 forced out.

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

[0106] In some embodiments, the first direction X is parallel to a thickness direction of the battery cell 7. In the battery, a plurality of 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 buffer member 30, and the lower the gravimetric energy density of the battery cell 7. The inventors have found that when the value of D3 exceeds a certain range, the effect of the buffer member 30 in improving the cycle characteristics of the electrode assembly 10 does not improve further with an increase in D3. The inventors have found through testing that by limiting the value of D3 to 0.25·D2 or less, the amount of the buffer member 30 can be reduced, the energy density of the battery cell 7 can be improved, and the cycle characteristics of the electrode assembly 10 can be improved.

[0109] In some embodiments, the cushioning member 30 is a flat plate structure, which 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, oval, or other shape. Optionally, the cushioning member 30 is a rectangular plate.

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

[0112] The term "assembled" means that the buffer member 30 is closely attached to the surface of the electrode assembly 10. For example, the buffer member 30 may be attached to the electrode assembly 10 with an adhesive.

[0113] The buffer member 30 assembled to the electrode assembly 10 can be placed in the housing 21 together with the electrode assembly 10 to simplify the assembly process. The electrode assembly 10 can also limit the shaking of the buffer member 30 when the battery cell 7 receives an external impact, thereby reducing the risk of the buffer member 30 being displaced.

[0114] In some embodiments, the compressibility f of the buffer member 30 at a pressure of 2 MPa satisfies 1%≦f≦99%. Optionally, 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 being located on either side of the flat region 10a in a third direction Z, and the third direction Z being 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 in a fully charged state along the third direction Z is L2, and the size of one electrode assembly 10 in a fully charged state along the first direction X 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 having a flat structure, and the portion of the electrode sheet in the flat region 10a is in a substantially flat state. The curved region 10b is a region of the electrode assembly 10 having a curved structure, and the portion of the electrode sheet in the curved region 10b is in a substantially curved state. For example, the portion of the electrode sheet in the curved region 10b is curved to be substantially in a circular arc shape.

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

[0118] Since the gap between the bent region 10b of the electrode assembly 10 and the first side wall 211 is large, the expansion force due to the bent region 10b is small. Since the gap between the flat region 10a of the electrode assembly 10 and the first side wall 211 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 more, the expansion of 85% or more of the area 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, both ends of the cushioning member 30 extend beyond the flat region 10a in the third direction Z. The cushioning 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 leads to an increase in the volume and weight of the buffer member 30. In this embodiment, the value of L1 is set to 1.1·L2 or less, thereby reducing the amount of the buffer member 30 and improving the energy density of the battery cell 7.

[0121] In some embodiments, the area of ​​the projection of the buffer member 30 on the inner surface of the first side wall 211 in the 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 presses against the electrode assembly 10 when the electrode assembly 10 expands, suppressing the expansion deformation of the electrode assembly 10. The shell 20 needs to accommodate other functional components in addition to the electrode assembly 10, and therefore a portion of the inner surface of the first side wall 211 does not press against the electrode assembly 10. In the embodiment of the present application, S1≦0.95·S2 reduces the overall usage of the buffer member 30, and provides more space for other components in 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 of the cushioning members 30 in the uncompressed state along the first direction X is D5, and D5 satisfies 0.1 mm≦D5≦10 mm. Optionally, 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, it is necessary to arrange many buffer members 30 in the battery cell 7 to meet the needs, which results in a complicated structure and reduced assembly efficiency of the battery cell 7. Therefore, in the embodiment of the present application, the value of D5 is limited to 0.1 mm or more.

[0125] If D5 is too large, the weight of the cushioning member 30 is too large and the space occupied by the cushioning member 30 is too large, resulting in a decrease in the energy density of the battery cell 7. Therefore, in the embodiment of the present application, the value of D5 is limited to 10 mm or less.

[0126] In some embodiments, D5 satisfies 0.5 mm≦D5≦4 mm.

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

[0128] 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 in a second direction Y, where the second direction Y is perpendicular to the first direction X. The buffer member 30 has a size H1 along the second direction Y, and a first active material layer 112 is provided on the first body 111, and the first active material layer 112 has a size H2 along the second direction Y. 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 charging. In the embodiment of the present application, by limiting the value of H1 to 0.85·H2 or more, 85% or more of the expansion of the area of ​​the first active material layer 112 in the second direction Y is absorbed by the buffer member 30, reducing the pressure received by 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. Exemplarily, 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 a negative electrode current collector.

[0131] In some embodiments, the first active material layer 112 includes a base region 112a and a thinned region 112b connected to the base region 112a, where the thinned region 112b has a thickness smaller than the thickness of the base region 112a. In the second direction Y, the thinned region 112b is located on a side of the base region 112a closer to the first tab 15. In the second direction Y, both ends of the buffer member 30 exceed the base region 112a.

[0132] When forming the first electrode 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 application, the thickness of the thin 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 larger expansion force during expansion than the thin-walled region 112b, in the embodiment of the present 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 laminated together. The separator 13 has a size H3 along the second direction Y, and H1 and H3 satisfy H1≦1.1·H3.

[0135] The separator 13 insulates the first body 111 from 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 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 cushioning member 30 extends beyond the separator 13, thereby reducing the amount of cushioning member 30 used, reducing the risk of the cushioning member 30 interfering with other components, and improving the energy density of the battery cell 7.

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

[0139] 9, in some embodiments, there are a plurality of electrode assemblies 10. A buffer member 30 is provided between at least two adjacent electrode assemblies 10.

[0140] By providing the buffer member 30 between two adjacent electrode assemblies 10, the risk of the buffer member 30 shaking when the battery cell 7 receives an external shock can be reduced.

[0141] 10 is a structural schematic diagram of a battery cell according to some other embodiments of the present application. As shown in FIG. 10, in some embodiments, there are a plurality of electrode assemblies 10 and a plurality of buffer members 30.

[0142] Exemplarily, there are two electrode assemblies 10 and two buffer members 30. The two electrode assemblies 10 are provided adjacent to each other to form an electrode unit, and the two buffer members 30 are respectively located on both sides of the electrode unit in the first direction X.

[0143] Fig. 11 is a structural schematic diagram of a battery cell according to some further embodiments of the present application. As shown in Fig. 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 to form an electrode unit, and the two buffer members 30 are respectively located on both sides 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 including a plurality of battery cells according to any one of the above embodiments.

[0145] According to some embodiments of the present application, the present application also provides a power consuming device, the power consuming device including a battery cell according to any one of the above embodiments, the battery cell being configured to supply electrical energy to the power consuming device.

[0146] According to some embodiments of the present application, referring to FIG. 10, a 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 arranged opposite to each other in a first direction X, and the distance between the two first side walls 211 in the first direction X is D1. The two electrode assemblies 10 are housed in 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 both sides of the electrode unit in the first direction X, respectively. The buffer members 30 are configured to be compressible, and the size of each buffer member 30 along the first direction X in an uncompressed state is D5, and the sum of the sizes of the two buffer members 30 along the first direction X in an uncompressed state is D3. D1, D2, and D3 satisfy 0.9≦(D2+D3) / D1≦1.5.

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

[0148] As shown in FIG. 12, the embodiment of the present application is as follows: A step S100 of providing a shell including two first side walls arranged opposite to each other along a first direction; Step S200 of providing an electrode assembly and a buffer member; and a step S300 of mounting the electrode assembly and the buffer member in the shell.

[0149] 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 in the first direction is D2. N buffer members are provided, where N is a positive integer greater than 0, and the N buffer members and the M electrode assemblies are stacked in the first direction. The buffer members are configured to be compressible, and the sum of the sizes of the N buffer members in the uncompressed state in the first direction is D3. D1, D2, and D3 satisfy 0.9≦(D2+D3) / D1≦1.5.

[0150] For the relevant structure of the battery cell manufactured by the above-mentioned battery cell manufacturing method, reference can be made to the battery cells according to the above-mentioned embodiments.

[0151] When manufacturing a battery cell using the above-mentioned battery cell manufacturing method, the steps do not have to be performed in the order described above, that is, the steps may be performed in the order described in the embodiment, or in an order different from that described in the embodiment, or some steps may be performed simultaneously. For example, steps S100 and S200 may be performed in any order, and may also be performed simultaneously.

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

[0153] As shown in FIG. 13, an embodiment of the present application provides a battery cell manufacturing system 90 including a first providing device 91, a second providing device 92, and an assembling device 93. The first providing device 91 is used to provide a shell including two first side walls arranged opposite to each other along a first direction. The second providing device 92 is used to provide an electrode assembly and a buffer member. The assembling device 93 is used to mount the electrode assembly and the buffer member in 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. N buffer members are provided, 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. 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.

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

[0155] In order to make the inventive object, technical solution and beneficial technical effects of the present application clearer, the present application will be described in more detail below with reference to the examples. However, it should be understood that the examples of the present application are merely for the purpose of interpreting the present application, and are not intended to limit the present application, and the examples of the present application are not limited to the examples described in the specification. Examples without specific experimental conditions or operating conditions are prepared under normal conditions or under conditions recommended by material suppliers.

[0156] Example 1 may be prepared 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 system was stirred with a vacuum mixer until it became uniform to obtain a positive electrode slurry. The positive electrode slurry was evenly applied onto an aluminum foil, dried at room temperature, transferred to an oven for further drying, and then cold-rolled, slit, and cut to obtain a positive electrode sheet.

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

[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, thoroughly dried lithium salt LiPF6 was dissolved in the mixed organic solvent to prepare an electrolyte solution with a concentration of 1 mol / L.

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

[0161] (v) The positive electrode sheet, the separator, and the negative electrode sheet were laminated and wound several times, and then pressed flat to produce an electrode assembly.

[0162] (vi) The two electrode assemblies and the two cushioning members are stacked and installed inside a housing, after which the end cover and the housing are welded together. After that, a battery cell is obtained by performing processes such as injecting electrolyte, leaving the assembly to stand, forming, and shaping.

[0163] In step (vi), as shown in Fig. 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 disposed opposite to 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 vernier caliper and found to be 27 mm. Before the buffer members 30 were attached to the housing 21, the thickness D5 of the buffer members 30 was measured with a vernier caliper and found to be 0.45 mm. In this case, the sum of the sizes of the two buffer members 30 in the first direction X in an uncompressed state was D3, and D3 was 0.9 mm.

[0164] The interface and cycle characteristics were detected for each of the two battery cells 7 manufactured by the above manufacturing steps.

[0165] Interface Detection One battery cell 7 was charged to full charge at a rate of 0.33 C in a loop at room temperature. When the battery cell 7 was fully charged, the battery cell 7 was disassembled, and the size of each electrode assembly 10 in the fully charged state along the first direction X was measured with a vernier caliper. After the size measurement was completed, the electrode assembly 10 was further disassembled, and the interface state of the negative electrode sheet was observed.

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

[0167] Cycle characteristic detection Another battery cell 7 was fixed to a jig, the two first side walls 211 of the battery cell 7 were clamped from both sides by the jig, and a clamping force of 3000 N was applied to the first side walls 211. The jig was provided with a press force sensor for detecting the press force F between the first side walls 211 and the jig in real time.

[0168] In a room temperature environment, the battery cell 7 was charged at a rate of 1C and discharged at a rate of 1C, thereby conducting a full charge / full discharge cycle test until the capacity of the battery cell 7 decreased to 90% of the initial capacity.

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

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

[0171] Example 2: The manufacturing method and detection method of the battery cell of Example 2 refer to Example 1, except that D3 is 1.4 mm.

[0172] Example 3: The manufacturing method and detection method of the battery cell of Example 3 refer to Example 1, except that D3 is 4.1 mm.

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

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

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

[0176] Example 7: The manufacturing method and detection method of the battery cell of Example 7 refer to Example 1, except that D3 is 0.7 mm and D2 is 23.6 mm.

[0177] Example 8: The manufacturing method and detection method of the battery cell of Example 8 refer to Example 1, except that D3 is 2.1 mm and D2 is 23.6 mm.

[0178] Comparative Example 1: The manufacturing method and detection method of the battery cell of Comparative Example 1 refer to Example 1, except 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 of the battery cell of Comparative Example 2 refer to Example 1, except 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 of the battery cell of Comparative Example 3 refer to Example 1, except 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 of the battery cell of Comparative Example 4 refer to Example 1, except that D3 is 0.6 mm and D2 is 21 mm.

[0182] Comparative Example 5: The manufacturing method and detection method of the battery cell of Comparative Example 5 refer to Example 1, except that D3 is 17.6 mm.

[0183] The evaluation results of Examples 1 to 8 and Comparative Examples 1 to 5 are shown in Table 1.

[0184] [Table 1]

[0185] In addition, in the axial direction of the winding of the electrode assembly, if the ratio of the wrinkle size to the size of the electrode sheet is less than 5%, it is considered that there are no wrinkles, if the ratio of the wrinkle size to the size of the electrode sheet is 5% to 30%, it is considered that there are slight wrinkles, and if the ratio of the wrinkle size to the size of the electrode sheet is more than 30%, it is considered that there are serious wrinkles.

[0186] With reference to Examples 1 to 8 and Comparative Examples 1 to 3, in the examples of the present application, the provision of a cushioning member reduces the risk of wrinkling of the electrode sheet when the battery cell is charged for the first time, reduces the expansion force generated in the battery cell during cycling, increases the number of cycles of the battery cell, and improves the cycle characteristics of the battery cell.

[0187] With reference to Examples 1 to 8 and Comparative Examples 4 to 5, in the examples of the present application, the value of (D2+D3) / D1 is limited to between 0.9 and 1.5, thereby reducing the risk of wrinkling the electrode sheet when the battery cell is charged for the first time, reducing the expansion force generated in the battery cell during cycling, increasing the number of cycles of the battery cell, and improving the cycle characteristics of the battery cell.

[0188] Although the present application has been described with reference to the preferred embodiments, various modifications may be made without departing from the scope of the present application, and the elements therein may be replaced with equivalents, and in particular, the technical features mentioned in each embodiment may be combined in any manner unless there is a structural contradiction. The present application is not limited to the specific embodiments disclosed in this specification, but includes all technical solutions within the scope of the claims. [Explanation of symbols]

[0189] The reference numerals in the drawings of specific embodiments are as follows: 1 vehicle 2 batteries 3. Controller 4 Motors 5 box body 5a 1st box part 5b 2nd box part 5c Storage space 6 Battery Module 7 Battery Cells 10 Electrode Assembly 11 First pole sheet 111 First Body 112 First active material layer 112a Base area 112b Thin area 12 Second Pole Sheet 13 Separator 14 Main body 15 First Tab 16 Second Tab 10a Flat area 10b Bend area 20 Shell 21 Housing 211 First side wall 212 Second side wall 22 End cover 30 Cushioning material 40 electrode terminal 90 Manufacturing System 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 including 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 a distance D1 between the two first side walls along the first direction; The M electrode assemblies are housed in the shell, and in a fully charged state, a sum of 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, the buffer members are configured to be compressible, a sum of sizes of the N buffer members along the first direction in an 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; 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 a thickness direction of the battery cell. The battery cell according to claim 1 or 2.

4. D2 and D3 satisfy D3≦0.25·D2. The battery cell according to any one of claims 1 to 3.

5. the electrode assembly includes a first pole sheet, the first pole sheet including a first body and a first tab extending from one end of the first body along a second direction, the second direction being perpendicular to the first direction; a size of the buffer member along the second direction is H1, a first active material layer is provided on the first body, and a size of the first active material layer along the second direction is H2; H1 and H2 satisfy H1≧0.85·H2. The battery cell according to any one of claims 1 to 4.

6. the first active material layer includes a base region and a thinned region connected to the base region, the thinned region having a thickness less than a thickness of the base region; In the second direction, the thin region is located on a 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 5 .

7. The electrode assembly further includes a separator, the separator and the first body being laminated together; The separator has a size H3 along the second direction, H1 and H3 satisfy H1≦1.1·H3. The battery cell according to claim 5 or 6.

8. In the second direction, neither end of the buffer member exceeds the separator. The battery cell according to claim 7.

9. the electrode assembly includes a flat region and two curved regions, the two curved regions being located on both sides of the flat region along a third direction, the third direction being perpendicular to the first direction; A size of the buffer member along the third direction is L1, a size of the electrode assembly along the third direction in a fully charged state is L2, and a size of one of the electrode assemblies along the first direction in a fully charged state is D4, L1, L2, and D4 satisfy L1≧0.85(L2−D4); The battery cell according to any one of claims 1 to 8.

10. In the third direction, both ends of the cushioning member extend beyond the flat region. The battery cell of claim 9 .

11. L1 and L2 satisfy L1≦1.1·L2. The battery cell according to claim 9 or 10.

12. an area of ​​the projection of the buffer member on an inner surface of the first side wall along the first direction is S1, an area of ​​the inner surface of the first side wall is S2, and S1 and S2 satisfy S1≦0.95·S2; The battery cell according to any one of claims 1 to 11.

13. Each of the cushioning members has a size D5 along the first direction in an uncompressed state, and D5 satisfies 0.1 mm≦D5≦10 mm. The battery cell according to any one of claims 1 to 12.

14. The compressibility f of the buffer member at a pressure of 2 MPa satisfies 1%≦f≦99%. The battery cell according to any one of claims 1 to 13.

15. The buffer member is assembled to the electrode assembly. The battery cell according to any one of claims 1 to 14.

16. The electrode assembly is a plurality of The buffer member is provided between at least two adjacent electrode assemblies. The battery cell according to any one of claims 1 to 15.

17. The cushioning member has a flat plate structure. The battery cell according to any one of claims 1 to 16.

18. A battery cell according to any one of claims 1 to 17, battery.

19. 1. A power consuming device, comprising: A battery cell according to any one of claims 1 to 17, wherein the battery cell is used to supply electrical energy. Power consuming device.

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