Cylindrical battery monomer, battery and power utilization device

Abstract

The embodiment of the utility model provides a cylindrical battery monomer, a battery and a power utilization device. The cylindrical battery cell includes a housing and an electrode assembly. And the diameter of each cylindrical battery monomer is greater than or equal to 40mm. At least a portion of the electrode assembly is housed within the housing. The electrode assembly comprises a positive plate, a negative plate and a separator, the positive plate, the negative plate and the separator are wound, and the separator separates the positive plate from the negative plate. And a negative active material of the negative plate comprises at least one of a silicon element and a carbon element. At least one of the positive plate, the negative plate and the separator comprises a base part and a plurality of supporting parts arranged on the base part. The base part is provided with two first surfaces which are oppositely arranged in the thickness direction of the base part. The plurality of supporting parts are convexly arranged on the at least one first surface so as to form a gap between the positive plate and the negative plate;

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and more particularly, to a cylindrical battery cell, a battery, and an electrical device. Background Art

[0002] Battery cells, especially cylindrical battery cells, are widely used in electronic devices such as mobile phones, laptop computers, battery cars, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools, etc.

[0003] With the gradual increase in the requirement for energy density, the diameter of the cylindrical battery cell gradually increases. However, as the diameter of the cylindrical battery cell gradually increases, the expansion force during the cycling process of the cylindrical battery cell becomes greater, and the expansion force will affect the cycling performance of the cylindrical battery cell. How to improve the cycling performance of large-diameter cylindrical battery cells is an important research direction in the technical field of batteries. Summary of the Utility Model

[0004] The present application provides a cylindrical battery cell, a battery, and an electrical device, which can improve reliability.

[0005] In a first aspect, an embodiment of the present application provides a cylindrical battery cell with a diameter ≥ 40 mm, including a housing and an electrode assembly. At least a part of the electrode assembly is accommodated in the housing. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator. The positive electrode sheet, the negative electrode sheet, and the separator are wound, and the separator separates the positive electrode sheet and the negative electrode sheet. The negative active material of the negative electrode sheet includes at least one of a silicon-based material and a carbon-based material. At least one of the positive electrode sheet, the negative electrode sheet, and the separator includes a base portion and a plurality of support portions provided on the base portion. The base portion has two first surfaces oppositely arranged along its own thickness direction. The plurality of support portions protrude from at least one of the first surfaces to form a gap between the positive electrode sheet and the negative electrode sheet.

[0006] The plurality of support portions protrude, which can support at least one of the positive electrode sheet and the negative electrode sheet, thereby forming a gap between the positive electrode sheet and the negative electrode sheet; during the cycling process of the cylindrical battery cell, the gap can provide space for the expansion of the negative electrode sheet, thereby reducing the extrusion of the electrolyte in the internal pores of the positive electrode film layer of the positive electrode sheet and the internal pores of the negative electrode film layer of the negative electrode sheet, reducing the concentration difference of the electrolyte in each region inside the electrode sheet, and improving the cycling performance of the cylindrical battery cell with a larger diameter. The gap can reduce the expansion amount of the electrode assembly, thereby reducing the extrusion force on the housing, reducing the risk of housing deformation and cracking, and improving the reliability of the cylindrical battery cell. By setting the gap, the increase in the expansion force caused by increasing the diameter of the cylindrical battery cell can be reduced, the diameter of the cylindrical battery cell can be increased, and the capacity of the cylindrical battery cell can be improved.

[0007] In some embodiments, the support portion is configured to be compressible. During the cycling of the cylindrical battery cell, the support portion can be compressed when subjected to pressure, thereby providing more expansion space for the negative electrode sheet. The compressible support portion can release stress through compression deformation to reduce the risk of the positive electrode sheet or the negative electrode sheet being damaged by the support portion and improve reliability.

[0008] In some embodiments, the plurality of support portions include a first support portion and a second support portion, and the height by which the first support portion protrudes from the first surface is greater than the height by which the second support portion protrudes from the first surface.

[0009] The first support portion has a relatively large height, which can support the positive electrode sheet or the negative electrode sheet to form a relatively large gap, thereby providing more space for the expansion of the negative electrode sheet. The second support portion has a relatively small height and occupies a relatively small space. As the negative electrode sheet expands, the gap gradually decreases; the second support portion can be compressed after the negative electrode sheet expands to a certain extent, which can reduce the pressure on the negative electrode sheet at the initial stage of expansion. When the second support portion is compressed, the second support portion can slow down the expansion of the negative electrode sheet to a certain extent, reduce the electrolyte extruded by the negative electrode sheet, and improve the cycling performance of the cylindrical battery cell.

[0010] In some embodiments, at least one of the positive electrode sheet, the negative electrode sheet, and the separator includes a plurality of organic particles, and the support portion includes organic particles. The organic particles can play a supporting role to form a gap. When thermal runaway occurs in the cylindrical battery cell, the organic particles can form a gel film structure at high temperature, thereby reducing the diffusion channels of active ions and delaying the time of thermal propagation, thus improving the reliability of the cylindrical battery cell.

[0011] In some embodiments, the plurality of organic particles include a first organic particle and a second organic particle, and the number-average particle diameter of the first organic particle is greater than the number-average particle diameter of the second organic particle. The first organic particle with a relatively large number-average particle diameter can support the positive electrode sheet or the negative electrode sheet to form a relatively large gap, thereby providing more space for the expansion of the negative electrode sheet. The second organic particle with a relatively small number-average particle diameter can be compressed after the negative electrode sheet expands to a certain extent, which can reduce the pressure on the negative electrode sheet at the initial stage of expansion. When the second organic particle is compressed, the second organic particle can slow down the expansion of the negative electrode sheet to a certain extent, reduce the electrolyte extruded by the negative electrode sheet, and improve the cycling performance of the cylindrical battery cell.

[0012] In some embodiments, the plurality of support portions include a first support portion and a second support portion, and the height by which the first support portion protrudes from the first surface is greater than the height by which the second support portion protrudes from the first surface. The plurality of organic particles include a first organic particle and a second organic particle; the first support portion includes the first organic particle, and the second support portion includes the second organic particle.

[0013] By setting the first organic particles and the second organic particles with different number-average particle sizes, the first support portion and the second support portion with different heights can be formed. The first support portion has a larger height, which can support the positive electrode sheet or the negative electrode sheet to form a larger gap, thereby providing more space for the expansion of the negative electrode sheet. The second support portion can be pressed after the negative electrode sheet expands to a certain extent, so that the pressure on the negative electrode sheet in the initial stage of expansion can be reduced. When the second support portion is pressed, the second support portion can slow down the expansion of the negative electrode sheet to a certain extent, reduce the electrolyte extruded by the negative electrode sheet, and improve the cycling performance of the cylindrical battery cell.

[0014] In some embodiments, the plurality of organic particles include first organic particles, and the first organic particles include a homopolymer or copolymer of a fluoroalkenyl monomer unit, a homopolymer or copolymer of an alkenyl monomer unit, a homopolymer or copolymer of an unsaturated nitrile monomer unit, a homopolymer or copolymer of an alkylene oxide monomer unit, and one or more of modified compounds of the above homopolymers or copolymers.

[0015] In some embodiments, the first organic particles include polytetrafluoroethylene, polytrifluorochloroethylene, polyvinyl fluoride, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylonitrile, polyethylene oxide, copolymers of different fluoroalkenyl monomer units, copolymers of fluoroalkenyl monomer units and alkenyl monomer units, copolymers of fluoroalkenyl monomer units and acrylic monomer units, copolymers of fluoroalkenyl monomer units and acrylate monomer units, and one or more of modified compounds of the above homopolymers or copolymers.

[0016] In some embodiments, the plurality of organic particles include second organic particles, and the second organic particles include a homopolymer or copolymer of an acrylate monomer unit, a homopolymer or copolymer of an acrylic monomer unit, a homopolymer or copolymer of a styrene monomer unit, a polyurethane compound, a rubber compound, and one or more of modified compounds of the above homopolymers or copolymers.

[0017] In some embodiments, the second organic particles include a copolymer of an acrylate monomer unit and a styrene monomer unit, a copolymer of an acrylic monomer unit and a styrene monomer unit, a copolymer of an acrylic monomer unit - acrylate monomer unit - styrene monomer unit, a copolymer of a styrene monomer unit and an unsaturated nitrile monomer unit, a copolymer of a styrene monomer unit - alkenyl monomer unit - unsaturated nitrile monomer unit, and one or more of modified compounds of the above copolymers.

[0018] In some embodiments, the outer shell includes a side wall surrounding the electrode assembly. The thickness of the side wall is 0.3 mm to 1.5 mm, and the material of the side wall includes steel. By providing a gap in this application, the expansion force exerted by the electrode assembly on the side wall can be reduced. Therefore, the steel side wall can have a thickness less than or equal to 1.5 mm, thereby improving the energy density of the cylindrical battery cell. The thickness of the steel side wall is greater than or equal to 0.3 mm to reduce the risk of deformation and rupture of the side wall under the expansion force of the electrode assembly, and improve the reliability of the cylindrical battery cell.

[0019] In some embodiments, the thickness of the side wall is 0.3 mm - 1.2 mm, optionally 0.3 mm - 0.9 mm, and further optionally 0.3 mm - 0.6 mm.

[0020] In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one side of the negative electrode current collector and containing a negative electrode active material. The negative electrode active material includes a silicon-based material, and the mass content of silicon element in the silicon-based material in the negative electrode film layer is 2% to 19%.

[0021] The introduction of the silicon-based material can increase the capacity of the negative electrode active material and improve the energy density of the cylindrical battery cell; the gap can provide space for the expansion of the negative electrode sheet, thereby reducing the influence of the silicon-based material on the expansion force. In the embodiments of this application, the mass content of the silicon-based material in the negative electrode film layer is limited to the above range to balance the expansion and capacity of the negative electrode sheet to a certain extent, and take into account the cycle performance and energy density of the cylindrical battery cell.

[0022] In some embodiments, the mass content of silicon element in the silicon-based material in the negative electrode film layer is 6% to 13%.

[0023] In some embodiments, the areal capacity density of the negative electrode sheet is greater than or equal to 3.2 mAh / cm 2 . In the embodiments of this application, by providing a gap, the influence of increasing the areal density of the negative electrode sheet on the expansion force can be reduced, thereby increasing the capacity of the negative electrode sheet and improving the energy density of the cylindrical battery cell.

[0024] In some embodiments, the areal capacity density of the negative electrode sheet is 3.3 mAh / cm 2 to 11.5 mAh / cm 2 . In the embodiments of this application, the capacity and expansion of the negative electrode sheet can be balanced to a certain extent, and the energy density and cycle performance of the cylindrical battery cell can be taken into account.

[0025] In some embodiments, the areal capacity density of the negative electrode sheet is 3.96 mAh / cm 2 to 7.56 mAh / cm 2 , which can further take into account the energy density and cycle performance of the cylindrical battery cell.

[0026] In some embodiments, the gap extends along the winding direction of the electrode assembly, and the gap has a winding start end and a winding end end.

[0027] In some embodiments, the radial dimension of at least part of the gap is 5 μm - 60 μm. Defining the radial dimension W of at least part of the gap to be greater than or equal to 5 μm can provide space for the expansion of the negative electrode sheet, reduce the expansion force, improve the cycling performance of the cylindrical battery cell, and reduce the risk of deformation and cracking of the outer shell. In the embodiments of the present application, the radial dimension W of at least part of the gap is defined to be less than or equal to 60 μm to shorten the ion migration path between the positive and negative electrode sheets, reduce the internal resistance of the cylindrical battery cell, reduce heat generation, and reduce the impact of the gap on the energy density.

[0028] In some embodiments, the radial dimension of the part of the gap near the winding start end is greater than or equal to the radial dimension of the part of the gap near the winding end end. The part of the gap near the winding start end has a larger radial dimension to provide more expansion space for the negative electrode sheet in the middle of the electrode assembly, reduce the risk of the middle of the electrode assembly collapsing due to expansion, and improve the cycling performance of the cylindrical battery cell.

[0029] In some embodiments, the radial dimension of at least part of the gap gradually decreases along the winding direction. The radial dimension of the gap changes smoothly, reducing the sudden change in the radial dimension of the gap, reducing the stress concentration of the negative electrode sheet, and improving the cycling performance of the battery cell.

[0030] In some embodiments, the gap includes a middle region and two end regions arranged along the axial direction of the cylindrical battery cell. The middle region is located between the two end regions, and the radial dimension of the middle region is smaller than the radial dimension of the end regions. The end regions have a larger radial dimension to facilitate the entry of the electrolyte into the gap, improve the wetting effect of the electrolyte on the electrode sheet, and enhance the cycling performance of the cylindrical battery cell.

[0031] In some embodiments, in the direction from the end region to the middle region, the radial dimension of the gap gradually decreases to reduce the sudden change in the radial dimension of the gap, reduce the stress concentration of the negative electrode sheet, and improve the cycling performance of the battery cell.

[0032] In some embodiments, the separator includes a base and a plurality of support portions, and the support portions include organic particles provided on the base. The organic particles can support the positive electrode sheet or the negative electrode sheet to increase the gap and provide space for the expansion of the negative electrode sheet.

[0033] In some embodiments, the base of the separator includes a base film and an inorganic particle layer provided on the base film, and the organic particles at least partially protrude from the inorganic particle layer. The inorganic particle layer includes a plurality of inorganic particles, and sufficient and unevenly distributed voids are formed between the inorganic particles and the organic particles, which can improve the air permeability of the separator and make the cylindrical battery cell have better cycling performance and reliability.

[0034] In some embodiments, a plurality of support portions are provided on a side of the positive electrode sheet facing the separator, and a plurality of support portions are provided on a side of the separator facing the positive electrode sheet. At least a part of the plurality of support portions of the positive electrode sheet facing the separator and the plurality of support portions of the separator facing the positive electrode sheet are disposed opposite to each other. By disposing the plurality of support portions of the positive electrode sheet and the plurality of support portions of the separator to face each other, at least a part of the plurality of support portions of the positive electrode sheet and the plurality of support portions of the separator can abut against each other to increase the gap and provide more space for the expansion of the negative electrode sheet.

[0035] In some embodiments, a plurality of support portions are provided on a side of the negative electrode sheet facing the separator, and a plurality of support portions are provided on a side of the separator facing the negative electrode sheet. At least a part of the plurality of support portions of the negative electrode sheet facing the separator and the plurality of support portions of the separator facing the negative electrode sheet are disposed opposite to each other. By disposing the plurality of support portions of the negative electrode sheet and the plurality of support portions of the separator to face each other, at least a part of the support portions of the negative electrode sheet and the support portions of the separator can abut against each other to increase the gap and provide more space for the expansion of the negative electrode sheet.

[0036] In some embodiments, a plurality of support portions are provided on a side of the negative electrode sheet facing the positive electrode sheet, and a plurality of support portions are provided on a side of the positive electrode sheet facing the negative electrode sheet. At least a part of the plurality of support portions of the negative electrode sheet facing the positive electrode sheet and the plurality of support portions of the positive electrode sheet facing the negative electrode sheet are disposed opposite to each other. By disposing the plurality of support portions of the negative electrode sheet and the plurality of support portions of the positive electrode sheet to face each other, the support portions of the negative electrode sheet and the support portions of the positive electrode sheet can support each other to increase the gap and provide more space for the expansion of the negative electrode sheet.

[0037] In some embodiments, a plurality of support portions are provided on both sides of the separator. The gap includes a first gap and a second gap. The first gap is formed between the positive electrode sheet and the separator, and the second gap is formed between the negative electrode sheet and the separator. By providing a plurality of support portions on both sides of the separator, the gap can be increased to provide more space for the expansion of the negative electrode sheet.

[0038] In some embodiments, one of the positive electrode sheet and the negative electrode sheet includes a first tab, and the other includes a second tab. The cylindrical battery cell includes a first electrode lead-out portion and a second electrode lead-out portion. The first electrode lead-out portion is electrically connected to the first tab, and the second electrode lead-out portion is electrically connected to the second tab. In the axial direction of the cylindrical battery cell, the first electrode lead-out portion and the second electrode lead-out portion are located on the same side of the electrode assembly. When a plurality of cylindrical battery cells are assembled into a group, the first electrode lead-out portions and the second electrode lead-out portions of the plurality of cylindrical battery cells can be arranged on the same side, which is convenient for connecting the busbar component to the first electrode lead-out portion and the second electrode lead-out portion and simplifies the battery structure.

[0039] In some embodiments, the housing includes a shell and an end cap, the shell includes an integrally formed side wall and end wall, the side wall surrounds the electrode assembly, the end wall and the end cap are opposite to each other along the axial direction of the cylindrical battery cell, and the end cap is sealed to the side wall.

[0040] In some embodiments, one of the positive electrode sheet and the negative electrode sheet includes a first pole ear, and the other includes a second pole ear. The cylindrical battery cell also includes an electrode terminal insulated and arranged on the end wall, one of the first pole ear and the second pole ear is electrically connected to the electrode terminal, and the other is electrically connected to the end wall. The electrode terminal and the end wall can serve as two exposed electrodes of the cylindrical battery cell. The electrode terminal and the end wall are located on the same side, which is conducive to assembling multiple cylindrical battery cells into groups and simplifying the battery structure.

[0041] In some embodiments, the cylindrical battery cell further comprises a first current collecting member, which is located on a side of the first pole tab facing the end wall and connected to the first pole tab. The electrode terminal abuts against and is connected to a surface of the first current collecting member facing the end wall. The first current collecting member can play a role of transition to achieve electrical connection between the first pole tab and the electrode terminal.

[0042] In some embodiments, a terminal recess is provided on the side of the electrode terminal facing the first current collecting member, and / or a terminal recess is provided on the side of the electrode terminal facing away from the first current collecting member. The bottom wall of the terminal recess is welded to the first current collecting member. By providing the terminal recess, the thickness of the bottom wall of the terminal recess can be reduced, the power required for welding the electrode terminal and the first current collecting member from the outside can be reduced, the risk of particles generated by welding falling into the outer shell can be reduced, and the reliability of the cylindrical battery cell can be improved.

[0043] In some embodiments, the first electrode tab and the second electrode tab are both located at one end of the electrode assembly facing the end wall. The first electrode tab and the second electrode tab can share space in the axial direction, thereby improving space utilization and increasing energy density.

[0044] In some embodiments, the first tab is located at one end of the electrode assembly facing the end wall, and the second tab is located at one end of the electrode assembly facing the end cap. The cylindrical battery cell also includes a second current collecting member connected to the second tab; the second current collecting member is connected to at least one of the end cap and the side wall.

[0045] In some embodiments, the height of the outer shell is 1.3 to 4 times the diameter of the outer shell. When the outer shell meets the above size requirements, the structural stability of the outer shell can be higher, which can improve the reliability of the cylindrical battery cell.

[0046] In some embodiments, the height of the housing is 50 mm to 150 mm.

[0047] In some embodiments, the diameter of the housing is 45 mm to 80 mm.

[0048] In a second aspect, an embodiment of the present application provides a battery, including a plurality of cylindrical battery cells provided in any of the embodiments of the first aspect.

[0049] In a third aspect, an embodiment of the present application provides an electrical device, including the battery provided in any of the embodiments of the second aspect, and the battery is used to provide electrical energy. Description of the Drawings

[0050] To more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced below. Obviously, the following described drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to the drawings without creative efforts.

[0051] Figure 1 Structural schematic diagram of a vehicle provided in some embodiments of the present application;

[0052] Figure 2 Explosion schematic diagram of a battery provided in some embodiments of the present application;

[0053] Figure 3 For Figure 2 Structural schematic diagram of the battery module shown;

[0054] Figure 4 Structural schematic diagram of a cylindrical battery cell in some embodiments of the present application;

[0055] Figure 5 For Figure 4 Explosion schematic diagram of the cylindrical battery cell shown;

[0056] Figure 6 Cross-sectional schematic diagram of the electrode assembly of a cylindrical battery cell provided in some embodiments of the present application;

[0057] Figure 7 For Figure 6 Enlarged schematic diagram at the dashed box A;

[0058] Figure 8 Schematic diagram of the separator of the electrode assembly of a cylindrical battery cell provided in some embodiments of the present application;

[0059] Figure 9 Partial cross-sectional schematic diagram of the electrode assembly of a cylindrical battery cell provided in some other embodiments of the present application;

[0060] Figure 10 Schematic diagram of the separator of the electrode assembly of a cylindrical battery cell provided in some other embodiments of the present application;

[0061] Figure 11Partial cross-sectional schematic view of the electrode assembly of the cylindrical battery cell provided by some other embodiments of the present application;

[0062] Figure 12 Schematic view of the flattened positive electrode sheet of the electrode assembly provided by some embodiments of the present application;

[0063] Figure 13 Cross-sectional schematic view of the positive electrode sheet of the electrode assembly provided by some embodiments of the present application;

[0064] Figure 14 Cross-sectional schematic view of the negative electrode sheet of the electrode assembly provided by some embodiments of the present application;

[0065] Figure 15 Cross-sectional schematic view of the positive electrode sheet provided by some other embodiments of the present application;

[0066] Figure 16 Cross-sectional schematic view of the negative electrode sheet provided by some other embodiments of the present application;

[0067] Figure 17 Partial cross-sectional view of the electrode assembly of the cylindrical battery cell provided by some other embodiments of the present application;

[0068] Figure 18 Partial cross-sectional view of the electrode assembly of the cylindrical battery cell provided by some other embodiments of the present application;

[0069] Figure 19 For Figure 4 Cross-sectional schematic view of the shown battery cell;

[0070] Figure 20 For Figure 19 Enlarged schematic view at the round frame;

[0071] Figure 21 Partial cross-sectional schematic view of the battery cell provided by some other embodiments of the present application.

[0072] In the drawings, the drawings are not drawn to actual scale.

[0073] Explanation of reference numerals is as follows:

[0074] 1, vehicle; 2, battery; 3, controller; 4, motor; 5, box; 5a, first box part; 5b, second box part; 5c, accommodation space; 6, battery module; 7, cylindrical battery cell; 7a, first electrode lead-out part; 7b, second electrode lead-out part;

[0075] 10, electrode assembly; 10a, first tab; 10b, second tab; 10c, electrode body;

[0076] 11. Positive electrode sheet; 111. Positive electrode base; 112. Positive electrode protrusion; 113. Positive electrode recess; 11a. Positive electrode current collector; 11b. Positive electrode film layer; 11c. Positive electrode particle coating;

[0077] 12. Negative electrode sheet; 121. Negative electrode base; 122. Negative electrode protrusion; 123. Negative electrode recess; 12a. Negative electrode current collector; 12b. Negative electrode film layer; 12c. Negative electrode particle coating;

[0078] 13. Separator; 131. Separator base; 13a. Base film; 13b. Coating;

[0079] 14. Support part; 141. First support part; 142. Second support part;

[0080] 15. Base; 151. First surface;

[0081] 20. Outer shell; 21. Housing; 211. End wall; 212. Side wall; 22. End cover;

[0082] 30. Electrode terminal; 31. Terminal recess; 32. Through hole;

[0083] 40. First current collecting member; 50. Cover plate; 60. Second current collecting member;

[0084] G. Gap; G1. First gap; G2. Second gap;

[0085] C1. Middle region; C2. End region; C3. Transition region;

[0086] E1. Winding start end; E2. Winding end; E3. Positive electrode winding start end; E4. Positive electrode winding end; E5. Negative electrode winding start end; E6. Negative electrode winding end; E7. First end; E8. Second end;

[0087] P. Organic particles; P1. First organic particles; P2. Second organic particles; P3. Inorganic particle layer;

[0088] V. Winding direction; Z. Axial direction. Detailed implementation manners

[0089] 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 will be clearly described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0090] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs; the terms used in the description of this application in the specification are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the description and claims of this application and the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the description and claims of this application or the above drawings are used to distinguish different objects and not to describe a specific order or primary-secondary relationship.

[0091] Reference to "embodiment" in this application means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of this application. The phrase appearing at various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments.

[0092] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected to", and "attached to" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0093] The term "and / or" in this application is merely a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally represents an "or" relationship between the associated objects before and after.

[0094] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, in different embodiments, the detailed description of the same components is omitted. It should be understood that the thickness, length, width, etc. of various components in the embodiments of this application shown in the drawings, as well as the overall thickness, length, width, etc. of the integrated device, are only for illustrative purposes and should not constitute any limitation to this application.

[0095] The term "a plurality of" as used in this application refers to two or more (including two).

[0096] The cylindrical battery cell can be a cylindrical secondary battery, and a secondary battery refers to a battery cell that can be activated by charging after discharging and can continue to be used.

[0097] A battery may refer to a single physical module that includes one or more cylindrical battery cells to provide higher voltage and capacity.

[0098] A cylindrical battery cell generally includes an electrode assembly and a housing for accommodating the electrode assembly. The electrode assembly generally includes a positive electrode sheet, a negative electrode sheet, and a separator, and the separator separates the positive electrode sheet and the negative electrode sheet.

[0099] During the cyclic charge and discharge process of the cylindrical battery cell, the negative electrode sheet expands due to the insertion of ions; as the diameter of the cylindrical battery cell increases, the expansion amount of the negative electrode sheet accumulates and may generate a greater expansion force, which will cause an increase in the pressure between the positive electrode sheet and the negative electrode sheet, resulting in the electrolyte in the pores inside the positive electrode film layer of the positive electrode sheet and the electrolyte in the pores inside the negative electrode film layer of the negative electrode sheet being extruded, affecting the cyclic performance of the cylindrical battery cell.

[0100] In addition, the expanded electrode assembly will also squeeze the housing, triggering the risk of deformation or even rupture of the housing, affecting the use reliability of the cylindrical battery cell.

[0101] In view of this, the embodiments of the present application provide a technical solution, in which at least one of the positive electrode sheet, the negative electrode sheet, and the separator is provided with a plurality of support portions to form a gap between the positive electrode sheet and the negative electrode sheet, and the gap can provide space for the expansion of the negative electrode sheet, thereby reducing the expansion force, improving the cyclic performance of the cylindrical battery cell, and enhancing the reliability of the cylindrical battery cell.

[0102] The cylindrical battery cell described in the embodiments of the present application is applicable to batteries and electrical devices using the batteries.

[0103] The electrical devices disclosed in the embodiments of the present application may be devices using batteries as power sources or various energy storage systems using batteries as energy storage elements. The electrical devices may be, but are not limited to, mobile phones, tablets, laptop computers, electric toys, power tools, battery cars, electric vehicles, ships, spacecraft, and the like. Among them, the electric toys may include fixed or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys, and electric aircraft toys, and the spacecraft may include airplanes, rockets, space shuttles, and spaceships, and the like.

[0104] For the convenience of description, the following embodiments take a vehicle as an example of the electrical device for illustration.

[0105] Figure 1 It is a schematic structural diagram of a vehicle provided in some embodiments of the present application.

[0106] As Figure 1 shown, a battery 2 is disposed inside a vehicle 1, and the battery 2 may be disposed at the bottom, head, or tail of the vehicle 1. The battery 2 can be used for power supply of the vehicle 1. For example, the battery 2 can be used as an operating power source of the vehicle 1.

[0107] The vehicle 1 may also include a controller 3 and a motor 4. The controller 3 is used to control the battery 2 to supply power to the motor 4. For example, it is used for the power requirements during the startup, navigation, and driving of the vehicle 1.

[0108] In some embodiments of the present application, the battery 2 can not only be used as the operating power source of the vehicle 1, but also as the driving power source of the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0109] Figure 2 An explosion schematic diagram of the battery provided for some embodiments of the present application. As Figure 2 shown, the battery 2 includes a box body 5 and cylindrical battery cells ( Figure 2 not shown), and the cylindrical battery cells are accommodated in the box body 5.

[0110] The box body 5 is used to accommodate the cylindrical battery cells, and the box body 5 can have various structures. In some embodiments, the box body 5 may include a first box body part 5a and a second box body part 5b. The first box body part 5a and the second box body part 5b cover each other, and the first box body part 5a and the second box body part 5b jointly define an accommodation space 5c for accommodating the cylindrical battery cells. The second box body part 5b can be a hollow structure with one end open, and the first box body part 5a is a plate-like structure. The first box body part 5a covers the opening side of the second box body part 5b to form the box body 5 with the accommodation space 5c; both the first box body part 5a and the second box body part 5b can also be hollow structures with one side open, and the opening side of the first box body part 5a covers the opening side of the second box body part 5b to form the box body 5 with the accommodation space 5c. Of course, the first box body part 5a and the second box body part 5b can have various shapes, such as a cylinder, a cuboid, etc.

[0111] To improve the sealing performance after the connection between the first box body part 5a and the second box body part 5b, a sealing member, such as sealant, sealing ring, etc., can also be provided between the first box body part 5a and the second box body part 5b.

[0112] Assuming that the first box body part 5a covers the top of the second box body part 5b, the first box body part 5a can also be called the upper box cover, and the second box body part 5b can also be called the lower box body.

[0113] In battery 2, there can be one or multiple cylindrical battery cells. If there are multiple cylindrical battery cells, they can be connected in series, parallel, or a combination of both (mixed connection, which means there are both series and parallel connections among multiple cylindrical battery cells). Multiple cylindrical battery cells can be directly connected in series, parallel, or in a mixed manner, and then the whole formed by multiple cylindrical battery cells is accommodated in the box body 5. Of course, it is also possible that multiple cylindrical battery cells are first connected in series, parallel, or in a mixed manner to form a battery module 6, and then multiple battery modules 6 are connected in series, parallel, or in a mixed manner to form a whole and are accommodated in the box body 5.

[0114] The cylindrical battery cell can be the smallest unit that makes up the battery.

[0115] In some embodiments, the box body 5 can be part of the chassis structure of a vehicle. For example, part of the box body 5 can become at least part of the vehicle floor, or part of the box body 5 can become at least part of the crossbeam and longitudinal beam of the vehicle.

[0116] In some embodiments, the battery 2 can be an energy storage device. The energy storage device includes an energy storage container, an energy storage electrical cabinet, etc.

[0117] Figure 3 For Figure 2 The structural schematic diagram of the battery module shown.

[0118] In some embodiments, as Figure 3 shown, there are multiple cylindrical battery cells 7. Multiple cylindrical battery cells 7 are first connected in series, parallel, or in a mixed manner to form a battery module 6. Multiple battery modules 6 are then connected in series, parallel, or in a mixed manner to form a whole and are accommodated in the box body.

[0119] The multiple cylindrical battery cells 7 in the battery module 6 can be electrically connected through a busbar component to achieve parallel, series, or mixed connection of the multiple cylindrical battery cells 7 in the battery module 6. The busbar component can be one or more, and each busbar component is used to electrically connect at least two cylindrical battery cells 7.

[0120] The cylindrical battery cell 7 can be a lithium-ion battery cell, a sodium-ion battery cell, a sodium-lithium-ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium-sulfur battery cell, a magnesium-ion battery cell, a nickel-metal hydride battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, etc.

[0121] Figure 4 The structural schematic diagram of the cylindrical battery cell in some embodiments of the present application; Figure 5 For Figure 4 The explosion schematic diagram of the cylindrical battery cell shown; Figure 6 The cross-sectional schematic diagram of the electrode assembly of the cylindrical battery cell provided in some embodiments of the present application; Figure 7 For Figure 6An enlarged schematic view at the dashed box A; Figure 8 Schematic diagram of a separator of an electrode assembly of a cylindrical battery cell provided by some embodiments of the present application.

[0122] Referring to Figures 4 to 8 , some embodiments of the present application provide a cylindrical battery cell 7, which includes a housing 20 and an electrode assembly 10, and at least a part of the electrode assembly 10 is accommodated in the housing 20.

[0123] The housing 20 is a hollow structure, and an accommodation space for accommodating the electrode assembly 10 and the electrolyte is formed inside it. The housing 20 of the cylindrical battery cell 7 is a cylindrical housing.

[0124] As an example, the housing 20 includes a housing body 21 and an end cap 22. The housing body 21 has an opening, and the end cap 22 is used to cover the opening.

[0125] The housing body 21 is a component for cooperating with the end cap 22 to form an internal cavity of the cylindrical battery cell 7. The formed internal cavity can be used to accommodate the electrode assembly 10, the electrolyte, and other components.

[0126] The housing body 21 and the end cap 22 can be independent components. Exemplarily, an opening can be provided on the housing body 21, and the end cap 22 is covered at the opening to form an internal cavity of the cylindrical battery cell 7.

[0127] The material of the housing body 21 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0128] The shape of the end cap 22 can be adapted to the shape of the housing body 21 to cooperate with the housing body 21. The material of the end cap 22 can be the same as or different from the material of the housing body 21. Optionally, the end cap 22 can be made of a material with a certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.). In this way, the end cap 22 is not easily deformed when being squeezed or collided, so that the cylindrical battery cell 7 can have a higher structural strength and the reliability performance can also be improved.

[0129] The end cap 22 is connected to the housing body 21 by welding, bonding, clamping or other means.

[0130] The housing body 21 can have an opening at one end or at both ends. In some examples, the housing body 21 can be a structure with an opening on one side, and the end cap 22 is provided as one and covers the housing body 21. In other examples, the housing body 21 can also be a structure with openings on both sides, and the end cap 22 is provided as two, and the two end caps 22 respectively cover the two openings of the housing body 21.

[0131] In some embodiments, the housing 21 includes a side wall 212 and an end wall 211 formed integrally. The end wall 211 and the end cap 22 face each other along the axial direction Z of the cylindrical battery cell. The end cap 22 is sealingly connected to the side wall 212.

[0132] The electrode assembly 10 is a component in the cylindrical battery cell 7 where an electrochemical reaction occurs. The electrode assembly 10 can be entirely accommodated within the outer casing 20, or partially accommodated within the outer casing 20. For example, a portion of the tab of the electrode assembly 10 can extend outside the outer casing 20.

[0133] Optionally, the electrode assembly 10 is entirely accommodated within the outer casing 20.

[0134] In some embodiments, the diameter of the cylindrical battery cell is greater than or equal to 40 mm. A cylindrical battery cell with a large diameter has a higher capacity, which is beneficial for improving the energy density when multiple cylindrical battery cells are assembled into a group.

[0135] In some embodiments, the electrode assembly 10 includes a positive electrode sheet 11 and a negative electrode sheet 12. During the charging and discharging process of the cylindrical battery cell 7, active ions (such as lithium ions) intercalate and deintercalate back and forth between the positive electrode sheet 11 and the negative electrode sheet 12.

[0136] In some embodiments, the positive electrode sheet 11 may include a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector.

[0137] As an example, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode film layer is provided on either or both of the two opposite surfaces of the positive electrode current collector.

[0138] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. can be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0139] As an example, the positive electrode film layer includes a positive electrode active material, and the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials can also be used. These positive electrode active materials can be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates may include but are not limited to lithium iron phosphate (such as LiFePO4 (which can also be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and at least one of a composite material of lithium manganese iron phosphate and carbon. Examples of lithium transition metal oxides may include but are not limited to lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which can also be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which can also be abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which can also be abbreviated as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which can also be abbreviated as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.80 Co 0.15 Al 0.05 O2) and their modified compounds, etc.

[0140] In some embodiments, the negative electrode sheet 12 may include a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector.

[0141] As an example, the negative electrode current collector can be a metal foil, a foam metal, a foam carbon, or a composite current collector. For example, as the metal foil, aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, titanium, etc. can be used. The foam metal can be foam nickel, foam copper, foam aluminum, foam alloy, etc. The composite current collector can include a polymer material substrate layer and a metal layer. The composite current collector can be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as substrates of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0142] As an example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0143] As an example, the negative electrode film layer includes a negative electrode active material. For example, the negative electrode active material can include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based materials can be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based materials can be selected from at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0144] In some embodiments, the material of the positive electrode current collector can be aluminum, and the material of the negative electrode current collector can be copper.

[0145] In some embodiments, the electrode assembly 10 further includes a separator 13, and the separator 13 is disposed between the positive electrode sheet 11 and the negative electrode sheet 12. The separator 13 can play a role in preventing short circuit between the positive and negative electrodes, and at the same time can allow active ions to pass through.

[0146] In some embodiments, the cylindrical battery cell 7 further includes an electrolyte, and the electrolyte plays a role in conducting ions between the positive electrode sheet 11 and the negative electrode sheet 12. The electrolyte can be liquid, gel, or solid.

[0147] In some embodiments, the liquid electrolyte includes an electrolyte salt and a solvent.

[0148] As an example, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium bis(oxalate) borate, lithium difluoro bis(oxalate) phosphate, and lithium tetrafluorooxalate phosphate.

[0149] As an example, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone. The solvent can also be an ether solvent. The ether solvent can include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether.

[0150] In some embodiments, the gel electrolyte includes a polymer as the skeletal network of the electrolyte, combined with an ionic liquid-lithium salt.

[0151] In some embodiments, the solid electrolyte includes a polymer solid electrolyte, an inorganic solid electrolyte, and a composite solid electrolyte.

[0152] As an example, the polymer solid electrolyte can be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, single-ion polymer, polyionic liquid-lithium salt, cellulose, etc.

[0153] As an example, the inorganic solid electrolyte can be an oxide solid electrolyte (crystalline perovskite, sodium superionic conductor, garnet, amorphous LiPON film), a sulfide solid electrolyte (crystalline lithium superionic conductor (lithium germanium phosphorus sulfur, argyrodite), amorphous sulfide), and one or more of a halide solid electrolyte, a nitride solid electrolyte, and a hydride solid electrolyte.

[0154] As an example, the composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to the polymer solid electrolyte.

[0155] In some embodiments, the positive electrode sheet 11, the negative electrode sheet 12, and the separator 13 are wound.

[0156] The electrode assembly 10 has a wound structure. Exemplarily, the positive electrode sheet 11, the separator 13, and the negative electrode sheet 12 are wound into a cylindrical wound structure.

[0157] In some embodiments, the diameter of the cylindrical battery cell 7 is greater than or equal to 40 mm. The cylindrical battery cell 7 includes a housing 20 and an electrode assembly 10, and at least a part of the electrode assembly 10 is accommodated in the housing 20.

[0158] As an example, the diameter of the housing is greater than or equal to 40 mm.

[0159] The electrode assembly 10 includes a positive electrode sheet 11, a negative electrode sheet 12, and a separator 13. The positive electrode sheet 11, the negative electrode sheet 12, and the separator 13 are wound, and the separator 13 separates the positive electrode sheet 11 and the negative electrode sheet 12.

[0160] The negative electrode active material of the negative electrode sheet 12 includes at least one of a silicon-based material and a carbon-based material.

[0161] At least one of the positive electrode sheet 11, the negative electrode sheet 12, and the separator 13 includes a base portion 15 and a plurality of support portions 14 provided on the base portion 15. The base portion 15 has two first surfaces 151 oppositely arranged along its own thickness direction, and the plurality of support portions 14 protrude from at least one of the first surfaces 151 to form a gap G between the positive electrode sheet 11 and the negative electrode sheet 12.

[0162] As an example, the carbon-based material includes at least one of artificial graphite and natural graphite.

[0163] As an example, the silicon-based material includes at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.

[0164] As an example, the plurality of support portions 14 are dispersedly arranged on the first surface 151.

[0165] In some examples, a plurality of support portions 14 protrude from one of the first surfaces 151 of the base portion 15. Of course, it can be the first surface 151 of the base portion 15 that protrudes a plurality of support portions 14 inward along the radial direction of the cylindrical battery cell, or it can be the first surface 151 of the base portion 15 that protrudes a plurality of support portions 14 outward along the radial direction of the cylindrical battery cell.

[0166] In some other examples, a plurality of support portions 14 are provided on both of the first surfaces 151 of the base portion 15.

[0167] In the electrode assembly 10, it can be that one of the positive electrode sheet 11, the negative electrode sheet 12, and the separator 13 is provided with the support portion 14, or it can be that two of them are provided with the support portion 14, or it can be that all three are provided with the support portion 14.

[0168] In some examples, the positive electrode sheet 11 includes a base portion and a plurality of support portions. For the convenience of description, the base portion of the positive electrode sheet 11 can be called the positive electrode base. Optionally, the negative electrode sheet 12 and the separator 13 can be provided with support portions or can be not provided with support portions. Among the plurality of support portions of the positive electrode sheet 11, it can be that some of the support portions are in contact with the separator, or it can be that all of the support portions are in contact with the separator.

[0169] In some examples, the negative electrode sheet 12 includes a base portion and a plurality of support portions. For the convenience of description, the base portion of the negative electrode sheet may be referred to as the negative electrode base. Optionally, the positive electrode sheet 11 and the separator 13 may or may not be provided with support portions. Among the plurality of support portions of the negative electrode sheet 12, some of the support portions may be in contact with the separator, or all of the support portions may be in contact with the separator.

[0170] In some examples, the separator 13 includes a base portion 15 and a plurality of support portions 14. For the convenience of description, the base portion of the separator 13 may be referred to as the separator base 131. Optionally, the positive electrode sheet 11 and the negative electrode sheet 12 may or may not be provided with support portions. As an example, the positive electrode sheet 11 may be in contact with some of the support portions of the separator 13, and / or the negative electrode sheet 12 may be in contact with some of the support portions of the separator 13.

[0171] As an example, the gap G may be a space located between the positive electrode sheet 11 and the negative electrode sheet 12 and not filled by the separator 13.

[0172] The support portions 14 may be rigid or flexible.

[0173] In some examples, at least two of the positive electrode sheet 11, the negative electrode sheet 12, and the separator 13 are provided with support portions 14, and the support portions 14 of the two may be formed in the same or different ways.

[0174] The plurality of support portions 14 protrude and can support at least one of the positive electrode sheet 11 and the negative electrode sheet 12, thereby forming a gap G between the positive electrode sheet 11 and the negative electrode sheet 12; during the cycling of the cylindrical battery cell 7, the gap G can provide space for the expansion of the negative electrode sheet 12, reduce the pressure between the positive electrode sheet 11 and the negative electrode sheet 12, thereby reducing the extrusion of the electrolyte in the internal pores of the positive electrode film layer of the positive electrode sheet 11 and the internal pores of the negative electrode film layer of the negative electrode sheet 12, and can reduce the concentration difference of the electrolyte in each region inside the electrode sheet, and improve the cycling performance of the cylindrical battery cell 7 with a larger diameter. The gap G can reduce the expansion amount of the electrode assembly 10, thereby reducing the extrusion force on the outer shell 20, reducing the risk of deformation and cracking of the outer shell 20, and improving the reliability of the cylindrical battery cell 7. By setting the gap G, the increase in the expansion force caused by increasing the diameter of the cylindrical battery cell 7 can be reduced, the diameter of the cylindrical battery cell 7 can be increased, and the capacity of the cylindrical battery cell 7 can be improved.

[0175] The gap G can also accommodate the electrolyte to improve the wetting effect of the electrolyte on the positive and negative electrode sheets and improve the cycling performance of the cylindrical battery cell.

[0176] In addition, when the problem of ion precipitation occurs during the cycling of the negative electrode sheet 12, such as lithium precipitation, the gap G can provide space for the deformation of the separator 13, so that the separator 13 can release the pressure exerted by the lithium dendrites through deformation, thereby avoiding the separator 13 being pierced to a certain extent, reducing the risk of short circuit, and improving the reliability.

[0177] In some embodiments, the negative electrode active material includes a carbon-based material. The carbon-based material has high cycling stability and can improve the cycling performance of the cylindrical battery cell.

[0178] In some embodiments, the support portion 14 is configured to be compressible. During the cycling of the cylindrical battery cell 7, the support portion 14 can be compressed when pressed, thereby providing more expansion space for the negative electrode sheet 12. The compressible support portion 14 can release stress through compression deformation to reduce the risk of the positive electrode sheet 11 or the negative electrode sheet 12 being damaged by the support portion 14 and improve the reliability.

[0179] In some embodiments, the plurality of support portions 14 include a first support portion 141 and a second support portion 142, and the height H1 of the first support portion 141 protruding from the first surface 151 is greater than the height H2 of the second support portion 142 protruding from the first surface 151.

[0180] The first support portion 141 can be one or more. The second support portion 142 can be one or more. Optionally, both the first support portion 141 and the second support portion 142 are plural.

[0181] The first support portion 141 has a larger height, which can support the positive electrode sheet 11 or the negative electrode sheet 12 to form a larger gap G, thereby providing more space for the expansion of the negative electrode sheet 12. The second support portion 142 has a smaller height and occupies less space. As the negative electrode sheet 12 expands, the gap G gradually shrinks; the second support portion 142 can be pressed after the negative electrode sheet 12 expands to a certain extent, which can reduce the pressure on the negative electrode sheet 12 at the initial stage of expansion. When the second support portion 142 is pressed, the second support portion 142 can slow down the expansion of the negative electrode sheet 12 to a certain extent, reduce the electrolyte squeezed out by the negative electrode sheet 12, and improve the cycling performance of the cylindrical battery cell 7.

[0182] In some embodiments, the first support portion 141 is plural and the second support portion 142 is plural.

[0183] In some embodiments, the height of the first support portion 141 is 1.1 to 15 times, optionally 2 to 7 times, the height of the second support portion 142.

[0184] In some embodiments, the separator 13 includes a separator base 131 and a plurality of support portions 14. Optionally, the plurality of support portions 14 of the separator 13 include a first support portion 141 and a second support portion 142.

[0185] In some embodiments, at least one of the positive electrode sheet 11, the negative electrode sheet 12, and the separator 13 includes a plurality of organic particles P, and the support portion 14 includes organic particles P.

[0186] Exemplarily, in the electrode assembly 10, organic particles P may be provided in one of the positive electrode sheet 11, the negative electrode sheet 12, and the separator 13, or both may be provided with organic particles P, or all three may be provided with organic particles P.

[0187] The organic particles P can play a supporting role to form a gap G. When thermal runaway occurs in the cylindrical battery cell 7, the organic particles P can form a gel film structure at high temperature, thereby reducing the diffusion channels of active ions, delaying the time of thermal propagation, and thus improving the reliability of the cylindrical battery cell 7.

[0188] Exemplarily, the organic particles P can be formed on the positive electrode sheet 11, the negative electrode sheet 12, or the separator 13 by coating. By adopting the method of coating the organic particles P to form the support portion 14, the forming process can be simplified.

[0189] In some embodiments, the plurality of organic particles P include a first organic particle P1 and a second organic particle P2, and the number-average particle size of the first organic particle P1 is greater than the number-average particle size of the second organic particle P2.

[0190] It should be noted that the number-average path of the organic particles is the arithmetic average of the particle sizes of the organic particles counted according to the number of organic particles. The particle size of the organic particles can refer to the distance between the two farthest points on the organic particles.

[0191] The first organic particle P1 with a larger number-average particle size can support the positive electrode sheet 11 or the negative electrode sheet 12 to form a larger gap G, so as to provide more space for the expansion of the negative electrode sheet 12. The second organic particle P2 with a smaller number-average particle size can be compressed after the negative electrode sheet 12 expands to a certain extent, so that the pressure on the negative electrode sheet 12 in the initial stage of expansion can be reduced. When the second organic particle P2 is compressed, the second organic particle P2 can slow down the expansion of the negative electrode sheet 12 to a certain extent, reduce the electrolyte extruded by the negative electrode sheet 12, and improve the cycle performance of the cylindrical battery cell 7.

[0192] In some embodiments, the plurality of support portions 14 include a first support portion 141 and a second support portion 142, and the height by which the first support portion 141 protrudes from the first surface is greater than the height by which the second support portion 142 protrudes from the first surface. The organic particles P include a first organic particle P1 and a second organic particle P2; the first support portion 141 includes the first organic particle P1, and the second support portion 142 includes the second organic particle P2.

[0193] By providing the first organic particle P1 and the second organic particle P2 with different number-average particle diameters, the first support portion 141 and the second support portion 142 with different heights can be formed. The first support portion 141 has a greater height, which can support the positive electrode sheet 11 or the negative electrode sheet 12 to form a larger gap G, thereby providing more space for the expansion of the negative electrode sheet 12. The second support portion 142 can be pressed after the negative electrode sheet 12 expands to a certain extent, so as to reduce the pressure on the negative electrode sheet 12 in the initial stage of expansion. When the second support portion 142 is pressed, the second support portion 142 can slow down the expansion of the negative electrode sheet 12 to a certain extent, reduce the electrolyte extruded by the negative electrode sheet 12, and improve the cycling performance of the cylindrical battery cell 7.

[0194] In some embodiments, the number-average particle diameter of the first organic particle P1 > 10 μm, and the number-average particle diameter of the second organic particle P2 is 2 μm - 10 μm.

[0195] In some embodiments, the number-average particle diameter of the first organic particle P1 is 12 μm - 25 μm. For example, the number-average particle diameter of the first organic particle P1 can be 12 μm, 13 μm, 15 μm, 16 μm, 18 μm, 20 μm, 21 μm, 22 μm, 24 μm, or 25 μm.

[0196] In some embodiments, the number-average particle diameter of the second organic particle P2 is 2 μm - 9 μm. For example, the number-average particle diameter of the first organic particle P1 can be 2 μm, 2.5 μm, 3 μm, 4 μm, 5 μm, 5.5 μm, 6 μm, 7 μm, 8 μm, or 9 μm.

[0197] In some embodiments, the ratio of the number-average particle diameter of the first organic particle P1 to the number-average particle diameter of the second organic particle P2 is greater than or equal to 1.5.

[0198] In some embodiments, the first organic particle P1 is a secondary particle.

[0199] In some embodiments, the second organic particle P2 is a primary particle.

[0200] It should be noted that the primary particles and secondary particles have meanings well-known in the art. A primary particle refers to a particle that has not formed an aggregated state. A secondary particle refers to an aggregated particle formed by the aggregation of two or more primary particles.

[0201] In some embodiments, the plurality of organic particles P includes a first organic particle P1, and the first organic particle P1 includes a homopolymer or copolymer of a fluoroalkenyl monomer unit, a homopolymer or copolymer of an alkenyl monomer unit, a homopolymer or copolymer of an unsaturated nitrile monomer unit, a homopolymer or copolymer of an alkylene oxide monomer unit, and one or more of modified compounds of the above homopolymers or copolymers.

[0202] In some embodiments, the fluoroalkenyl monomer unit may be selected from one or more of vinylidene fluoride, vinylidene difluoride, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, and hexafluoropropylene.

[0203] In some embodiments, the alkenyl monomer unit may be selected from one or more of ethylene, propylene, butadiene, isoprene, etc.

[0204] In some embodiments, the unsaturated nitrile monomer unit may be selected from one or more of acrylonitrile, methacrylonitrile, etc.

[0205] In some embodiments, the alkylene oxide monomer unit may be selected from one or more of ethylene oxide, propylene oxide, etc.

[0206] In some embodiments, the first organic particle P1 includes polytetrafluoroethylene, poly(chlorotrifluoroethylene), polyvinyl fluoride, poly(vinylidene fluoride), polyethylene, polypropylene, polyacrylonitrile, polyethylene oxide, copolymers of different fluoroalkenyl monomer units, copolymers of fluoroalkenyl monomer units and alkenyl monomer units, copolymers of fluoroalkenyl monomer units and acrylic monomer units, copolymers of fluoroalkenyl monomer units and acrylate monomer units, and one or more of modified compounds of the above homopolymers or copolymers.

[0207] In some embodiments, the first organic particle P1 may include one or more of a vinylidene fluoride - trifluoroethylene copolymer, a vinylidene fluoride - hexafluoropropylene copolymer, a vinylidene fluoride - trifluoroethylene - hexafluoropropylene copolymer, a vinylidene fluoride - hexafluoropropylene - acrylic acid copolymer, a vinylidene fluoride - hexafluoropropylene - acrylate copolymer, and modified compounds of the above copolymers.

[0208] In some embodiments, the plurality of organic particles P includes a second organic particle P2, and the second organic particle P2 includes a homopolymer or copolymer of acrylate monomer units, a homopolymer or copolymer of acrylic monomer units, a homopolymer or copolymer of styrene monomer units, polyurethane compounds, rubber compounds, and one or more of modified compounds of the above homopolymers or copolymers.

[0209] In some embodiments, the second organic particle P2 includes one or more of a copolymer of acrylate monomer units and styrene monomer units, a copolymer of acrylic monomer units and styrene monomer units, a copolymer of acrylic monomer units - acrylate monomer units - styrene monomer units, a copolymer of styrene monomer units and unsaturated nitrile monomer units, a copolymer of styrene monomer units - olefinic monomer units - unsaturated nitrile monomer units, and a modified compound of the above copolymers.

[0210] In some embodiments, the acrylate monomer units may be selected from one or more of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, butyl methacrylate, isooctyl methacrylate, etc.

[0211] In some embodiments, the acrylic monomer units may be selected from one or more of acrylic acid, methacrylic acid, etc.

[0212] In some embodiments, the styrene monomer units may be selected from one or more of styrene, methylstyrene, etc.

[0213] In some embodiments, the unsaturated nitrile monomer units may be selected from one or more of acrylonitrile, methacrylonitrile, etc.

[0214] In some embodiments, the second organic particle P2 may include one or more of butyl acrylate - styrene copolymer, butyl methacrylate - isooctyl methacrylate copolymer, isooctyl methacrylate - styrene copolymer, methacrylate - methacrylic acid - styrene copolymer, methyl acrylate - isooctyl methacrylate - styrene copolymer, butyl acrylate - isooctyl acrylate - styrene copolymer, butyl acrylate - isooctyl methacrylate - styrene copolymer, butyl methacrylate - isooctyl acrylate - styrene copolymer, butyl methacrylate - isooctyl methacrylate - styrene copolymer, styrene - acrylonitrile copolymer, styrene - butadiene - acrylonitrile copolymer, methyl acrylate - styrene - acrylonitrile copolymer, isooctyl methacrylate - styrene - acrylonitrile copolymer, styrene - vinyl acetate copolymer, styrene - vinyl acetate - pyrrolidone copolymer, and a modified compound of each of the above materials.

[0215] In some embodiments, the spacer 13 includes a base 15 and a plurality of support portions 14, and the support portions 14 include organic particles disposed on the base.

[0216] The organic particle P may protrude entirely from the base 15. Alternatively, a part of the organic particle is embedded in the base 15 and another part protrudes from the base 15.

[0217] The organic particles P can support the positive electrode sheet 11 or the negative electrode sheet 12 to increase the gap G and provide space for the expansion of the negative electrode sheet 12.

[0218] For simplicity of description, the base 15 of the separator 13 may be referred to as the separator base 131.

[0219] In some embodiments, the base 15 of the separator 13 includes a base film 13a and an inorganic particle layer P3 provided on the base film 13a, and the organic particles P at least partially protrude from the inorganic particle layer P3.

[0220] The inorganic particle layer P3 includes a plurality of inorganic particles, and sufficient and unevenly distributed voids are formed between the inorganic particles and the organic particles, which can improve the air permeability of the separator and enable the cylindrical battery cell to have better cycle performance and reliability.

[0221] In some embodiments, the separator 13 includes a coating 13b provided on at least one surface of the base film 13a. The coating 13b includes an inorganic particle layer P3 and a plurality of organic particles P.

[0222] In some examples, inorganic particles can be coated on the base film 13a first to form the inorganic particle layer P3, and then a plurality of organic particles can be coated on the inorganic particle layer P3. In other examples, the inorganic particles and the organic particles can be mixed first and then coated on the base film 13a together.

[0223] In some examples, one surface of the base film 13a is coated with a coating 13b including an inorganic particle layer P3 and a plurality of organic particles P, and the other surface of the base film 13a can be uncoated or can be coated with the inorganic particle layer P3. In other examples, both surfaces of the base film 13a are coated with a coating 13b including an inorganic particle layer P3 and organic particles P.

[0224] Sufficient and unevenly distributed voids are formed between the inorganic particles and the organic particles P, which can improve the air permeability of the separator 13 and enable the cylindrical battery cell 7 to have better cycle performance and reliability. The organic particles P can support the positive electrode sheet 11 or the negative electrode sheet 12 to increase the gap G and provide space for the expansion of the negative electrode sheet 12.

[0225] In some embodiments, the inorganic particles may include one or more of boehmite (γ-AlOOH), alumina (Al2O3), barium sulfate (BaSO4), magnesium oxide (MgO), magnesium hydroxide (Mg(OH)2), silicon dioxide (SiO2), tin dioxide (SnO2), titanium dioxide (TiO2), calcium oxide (CaO), zinc oxide (ZnO), zirconium oxide (ZrO2), yttrium oxide (Y2O3), nickel oxide (NiO), cerium oxide (CeO2), strontium titanate (SrTiO3), barium titanate (BaTiO3), magnesium fluoride (MgF2).

[0226] In some embodiments, the volume average particle size Dv50 of the inorganic particles is ≤ 2.5 μm; for example, the particle size of the inorganic particles can be 0.5 μm - 2.5 μm, 1.5 μm - 2.5 μm, 0.3 μm - 0.7 μm, etc.

[0227] In some embodiments, the surface of the base film 13a facing the positive electrode sheet 11 is coated with a coating 13b, and / or the surface of the base film 13a facing the negative electrode sheet 12 is coated with a coating 13b.

[0228] In some embodiments, the gap G extends along the winding direction V of the electrode assembly 10, and the gap G has a winding start end E1 and a winding end end E2.

[0229] The gap G winds into multiple turns along the winding direction V.

[0230] As an example, the positive electrode sheet 11 has a positive electrode winding start end E3 and a positive electrode winding end end E4, and the negative electrode sheet 12 has a negative electrode winding start end E5 and a negative electrode winding end end E6. Along the winding direction V, the negative electrode winding end end E6 extends beyond the positive electrode winding end end E4; along the opposite direction of the winding direction V, the negative electrode winding start end E5 extends beyond the positive electrode winding start end E3. Both ends of the negative electrode sheet 12 along the winding direction V extend beyond the positive electrode sheet 11, and the negative electrode sheet 12 can provide an embedding space for the active ions escaping from the positive electrode sheet 11, thereby reducing the risk of ion escape. In the radial direction of the cylindrical battery cell, the winding start end E1 of the gap G corresponds to the positive electrode winding start end E3, and the winding end end E2 of the gap G corresponds to the positive electrode winding end end E4.

[0231] In some embodiments, the radial dimension W of at least a part of the gap G is 5 μm - 60 μm.

[0232] As an example, the radial dimension of the gap G can be the dimension of the gap G along the radial direction of the cylindrical battery cell. The radial dimensions W of the gap G at different positions can be the same or different.

[0233] Optionally, the radial dimension W of each part of the gap G is 5 μm - 60 μm.

[0234] Optionally, the radial dimension W of the gap G can be 5 μm, 6 μm, 8 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm or a range composed of any two of the above values.

[0235] As an example, the radial dimension of the gap G can be measured in the following manner:

[0236] Discharge the cylindrical battery cell to the lower cut-off voltage (for example, 2.5 V);

[0237] Adopt CT (Computed Tomography) technology to obtain an image of the cross-section of the electrode assembly using X-rays, and this cross-section is perpendicular to the axial direction of the cylindrical battery cell.

[0238] Based on this image, measure the distance D1 between the outer surface of the 6th positive electrode sheet and the inner surface of the 10th positive electrode sheet in the radial direction of the electrode assembly.

[0239] Disassemble the cylindrical battery cell and measure the thickness t1 of the positive electrode sheet, the thickness t2 of the negative electrode sheet, and the thickness t3 of the separator.

[0240] There are 3 positive electrode sheets, 4 negative electrode sheets, and 8 separators between the outer surface of the 6th positive electrode sheet and the inner surface of the 10th positive electrode sheet; 8 gaps are formed between the outer surface of the 6th positive electrode sheet and the inner surface of the 10th positive electrode sheet. W = (D1 - 3×t1 - 4×t2 - 8×t3) / 8.

[0241] It should be noted here that D1 is measured at the position on the outer surface of the 6th positive electrode sheet where there is no support part and the position on the inner surface of the 10th positive electrode sheet where there is no support part. t1 is measured at the part of the positive electrode sheet where there is no support part. The thickness t2 is measured at the part of the negative electrode sheet where there is no support part. The thickness t3 is measured at the part of the separator where there is no support part.

[0242] In the embodiments of the present application, the radial dimension W of the gap G is limited to be greater than or equal to 5 μm, which can provide space for the expansion of the negative electrode sheet 12, reduce the expansion force, improve the cycling performance of the cylindrical battery cell 7, and reduce the risk of deformation and cracking of the outer shell 20. In the embodiments of the present application, the radial dimension W of the gap G is limited to be less than or equal to 50 μm to shorten the ion migration path between the positive electrode sheet 11 and the negative electrode sheet 12, reduce the internal resistance of the cylindrical battery cell 7, reduce heat generation, and reduce the influence of the gap G on the energy density.

[0243] Figure 9 It is a partial cross-sectional view schematic diagram of the electrode assembly of the cylindrical battery cell provided in other embodiments of the present application; Figure 10 It is a schematic diagram of the separator of the electrode assembly of the cylindrical battery cell provided in other embodiments of the present application.

[0244] Refer to Figure 9 and Figure 10 , in some embodiments, a plurality of support parts 14 are provided on both sides of the separator 13. The gap G includes a first gap G1 and a second gap G2. The first gap G1 is formed between the positive electrode sheet 11 and the separator 13, and the second gap G2 is formed between the negative electrode sheet 12 and the separator 13.

[0245] As an example, the radial dimension of the first gap G1 is W1, and the radial dimension of the second gap G2 is W2. The radial dimension W of the gap G = W1 + W2.

[0246] In the thickness direction of the separator 13, the support portions 14 located on both sides of the separator 13 may overlap or may not overlap.

[0247] By providing a plurality of support portions 14 on both sides of the separator 13, the gap G can be increased, providing more space for the expansion of the negative electrode sheet 12.

[0248] In some embodiments, coatings 13b are provided on both sides of the base film 13a.

[0249] Figure 11 It is a partial cross-sectional schematic diagram of the electrode assembly of the cylindrical battery cell provided by some other embodiments of the present application; Figure 12 It is a schematic diagram of the flattened positive electrode sheet of the electrode assembly provided by some embodiments of the present application; Figure 13 It is a cross-sectional schematic diagram of the positive electrode sheet of the electrode assembly provided by some embodiments of the present application; Figure 14 It is a cross-sectional schematic diagram of the negative electrode sheet of the electrode assembly provided by some embodiments of the present application.

[0250] Refer to Figures 11 to 14 , in some embodiments, the positive electrode sheet 11 is provided with support portions 14.

[0251] In the embodiments of the present application, the support portions 14 may be provided on one side of the positive electrode sheet 11, or may be provided on both sides of the positive electrode sheet 11.

[0252] In some embodiments, the positive electrode sheet 11 includes a positive electrode base portion 111 and a plurality of positive electrode protrusions 112 protruding from the surface of the positive electrode base portion 111. The positive electrode sheet 11 is provided with positive electrode recesses 113 corresponding to the positions of the positive electrode protrusions 112 on the side away from the positive electrode protrusions 112. The support portions 14 of the positive electrode sheet 11 include the positive electrode protrusions 112.

[0253] As an example, the number of the positive electrode recesses 113 is the same as that of the positive electrode protrusions 112, and they are arranged in one-to-one correspondence.

[0254] The positive electrode protrusions 112 can support the separator 13 and the negative electrode sheet 12, thereby forming the gap G. The positive electrode recesses 113 can accommodate the electrolyte and can also provide space for the expansion of the negative electrode sheet 12.

[0255] As an example, the positive electrode protrusions 112 and the positive electrode recesses 113 can be formed by stamping the positive electrode sheet 11.

[0256] In some embodiments, organic particles may be provided on the surface of the positive electrode protrusions 112.

[0257] In some embodiments, the positive electrode tab is connected to the positive electrode base 111.

[0258] In some embodiments, all the positive electrode protrusions 112 protrude toward the same side of the positive electrode base 111. Correspondingly, a plurality of support portions 14 are provided on the same side of the positive electrode base 111.

[0259] The embodiments of the present application can simplify the forming process of the positive electrode sheet 11.

[0260] In some embodiments, there are a plurality of positive electrode protrusions 112. A part of the positive electrode protrusions 112 protrude from the positive electrode base 111 to a relatively high height, and another part of the positive electrode protrusions 112 protrude from the positive electrode base 111 to a relatively low height. The first support portion includes the positive electrode protrusions 112 with a relatively high height, and the second support portion includes the positive electrode protrusions 112 with a relatively low height.

[0261] In some embodiments, a plurality of support portions 14 are provided on the side of the separator 13 facing the positive electrode recess 113, and at least part of the plurality of support portions 14 of the separator 13 do not overlap with the positive electrode recess 113 in the radial direction.

[0262] In some embodiments, the positive electrode sheet 11 includes a positive electrode current collector 11a and a positive electrode film layer 11b provided on the surface of the positive electrode current collector 11a. Exemplarily, the portion of the positive electrode current collector 11a where the positive electrode film layer 11b is not provided can be the positive electrode tab.

[0263] In some embodiments, the positive electrode protrusions 112 are formed in the region of the positive electrode sheet 11 where the positive electrode film layer 11b is provided.

[0264] In some embodiments, the negative electrode sheet 12 includes a negative electrode current collector 12a and a negative electrode film layer 12b provided on at least one side of the negative electrode current collector 12a and containing a negative electrode active material.

[0265] Exemplarily, the portion of the negative electrode current collector 12a where the negative electrode film layer 12b is not provided can be the negative electrode tab.

[0266] In some embodiments, the negative electrode active material includes a silicon-based material. The introduction of the silicon-based material can improve the capacity of the negative electrode active material and increase the energy density of the cylindrical battery cell 7; the gap G can provide space for the expansion of the silicon-based material, thereby reducing the influence of the silicon-based material on the expansion force.

[0267] Exemplarily, silicon elements can exist in the form of silicon-based materials. For example, the silicon-based materials can include at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.

[0268] In some embodiments, the mass content of silicon element in the silicon-based material in the negative electrode film layer 12b is 2% to 19%. Exemplarily, the mass content of silicon element in the negative electrode film layer can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or the range composed of any two of the above values.

[0269] The mass content of silicon element in the negative electrode film layer has the meaning well known in the art and can be detected by using the equipment and methods well known in the art. For example, the negative electrode sheet is soaked in a solvent (such as water) to separate the negative electrode active material from the negative electrode current collector, and each substance in the negative electrode film layer is obtained by suction filtration and used as a test sample. The test sample is analyzed by an ICAP7400 model inductively coupled plasma - emission spectrometer of Thermo Fisher Scientific Company in the United States with reference to the GB / T30902 - 2014 standard to obtain the silicon element content.

[0270] In the embodiments of the present application, the mass content of silicon element in the negative electrode film layer 12b is limited to be greater than or equal to 2% to increase the capacity of the negative electrode sheet and improve the energy density of the cylindrical battery cell; the gap G can provide space for the expansion of the negative electrode sheet, thereby reducing the influence of the silicon-based material on the expansion force. In the embodiments of the present application, the mass content of silicon element in the negative electrode film layer 12b is limited to be less than or equal to 19% to limit the expansion amount of the cylindrical battery cell and improve the cycle performance of the cylindrical battery cell.

[0271] In the embodiments of the present application, the mass content of silicon element in the negative electrode film layer 12b is limited to 2% to 19% to balance the expansion and capacity of the negative electrode sheet to a certain extent and take into account the cycle performance and energy density of the cylindrical battery cell.

[0272] In some embodiments, the mass content of silicon element in the negative electrode film layer 12b is 6% to 13%.

[0273] In some embodiments, the areal capacity density of the negative electrode sheet 12 is greater than or equal to 3.2 mAh / cm 2 .

[0274] The areal capacity density of the negative electrode sheet has a meaning well-known in the art and can be detected by using equipment and methods well-known in the art. For example, the above-mentioned negative electrode sheet and a lithium metal sheet are formed into a counter electrode, and together with an electrolyte and a separator, a CR2430 type button cell is assembled in a glove box under argon protection; after the obtained button cell is left standing for 12 h, at 25 °C, it is discharged at a constant current of 0.05 C to 0.005 V, left standing for 10 minutes, then discharged at a constant current of 50 μA to 0.005 V, left standing for 10 minutes, and then discharged at a constant current of 10 μA to 0.005 V; then it is charged at a constant current of 0.1 C to 2 V, and the charging capacity is recorded. The ratio of the charging capacity to the area of the negative electrode sheet is the areal capacity density. As an example, the electrolyte and the separator can be the electrolyte and the separator of Example 1 described below.

[0275] The areal density of the negative electrode sheet is related to the swelling of the negative electrode sheet. By setting a gap in the embodiments of the present application, the influence of increasing the areal density of the negative electrode sheet on the swelling force can be reduced, thereby increasing the capacity of the negative electrode sheet and improving the energy density of a single cylindrical battery.

[0276] Exemplarily, the areal capacity density of the negative electrode sheet 12 can be 3.2 mAh / cm 2 、3.3 mAh / cm 2 、3.33 mAh / cm 2 、3.5 mAh / cm 2 、3.8 mAh / cm 2 、3.9 mAh / cm 2 、4 mAh / cm 2 、4.2 mAh / cm 2 、4.5 mAh / cm 2 、4.8 mAh / cm 2 、4.9 mAh / cm 2 、5 mAh / cm 2 、5.2 mAh / cm 2 、5.5 mAh / cm 2 、5.8 mAh / cm 2 、6 mAh / cm 2 、6.2 mAh / cm 2 、6.5 mAh / cm 2 、6.8 mAh / cm 2 、7 mAh / cm 2 、7.5 mAh / cm 2 、8 mAh / cm 2 、8.5 mAh / cm 2 、9 mAh / cm 2 、9.5 mAh / cm 2 、10 mAh / cm 2 、10.5 mAh / cm2 、 11 mAh / cm 2 、 11.5 mAh / cm 2 or a range formed by any two of the above values.

[0277] In some embodiments, the areal capacity density of the negative electrode sheet 12 is 3.3 mAh / cm 2 to 11.5 mAh / cm 2 . The embodiments of the present application can, to a certain extent, balance the capacity and swelling of the negative electrode sheet, and take into account the energy density and cycle performance of the cylindrical battery cell.

[0278] In some embodiments, the areal capacity density of the negative electrode sheet 12 is 3.96 mAh / cm 2 to 7.56 mAh / cm 2 , which can further take into account the energy density and cycle performance of the cylindrical battery cell.

[0279] In some embodiments, the negative electrode sheet 12 is provided with a plurality of support portions 14.

[0280] In the embodiments of the present application, a plurality of support portions 14 may be provided on one side of the negative electrode sheet 12, or a plurality of support portions 14 may be provided on both sides of the negative electrode sheet 12.

[0281] In some embodiments, the negative electrode sheet 12 includes a negative electrode base portion 121 and a plurality of negative electrode protrusions 122 protruding from the surface of the negative electrode base portion 121. A negative electrode recess 123 corresponding to the position of the negative electrode protrusions 122 is provided on the side of the negative electrode sheet 12 away from the negative electrode protrusions 122. The support portion 14 of the negative electrode sheet 12 includes the negative electrode protrusions 122.

[0282] As an example, the number of the negative electrode recesses 123 is the same as that of the negative electrode protrusions 122, and they are arranged in one-to-one correspondence.

[0283] The negative electrode protrusions 122 can support the separator 13 and the positive electrode sheet 11, thereby forming a gap G. The negative electrode recesses 123 can accommodate the electrolyte and can also provide space for the swelling of the negative electrode sheet 12.

[0284] As an example, the negative electrode protrusions 122 and the negative electrode recesses 123 can be formed by stamping the negative electrode sheet 12.

[0285] In some embodiments, organic particles may be provided on the surface of the negative electrode protrusions 122.

[0286] In some embodiments, the negative electrode tab is connected to the negative electrode base portion 121.

[0287] In some embodiments, the number of the negative electrode protrusions 122 is plural.

[0288] In some embodiments, all the negative electrode protrusions 122 protrude toward the same side of the negative electrode base 121. Correspondingly, a plurality of support portions 14 are provided on the same side of the negative electrode base 121.

[0289] The embodiment of the present application can simplify the forming process of the negative electrode sheet 12.

[0290] In some embodiments, there are a plurality of negative electrode protrusions 122. The height of a part of the negative electrode protrusions 122 protruding from the negative electrode base 121 is relatively high, and the height of another part of the negative electrode protrusions 122 protruding from the negative electrode base 121 is relatively low. The first support portion includes the negative electrode protrusions 122 with a relatively high height, and the second support portion includes the negative electrode protrusions 122 with a relatively low height.

[0291] In some embodiments, a plurality of support portions 14 are provided on the side of the separator 13 facing the negative electrode recess 123, and at least a part of the plurality of support portions 14 of the separator 13 does not overlap with the negative electrode recess 123 in the radial direction.

[0292] In some embodiments, the negative electrode protrusions 122 are formed in the area of the negative electrode sheet 12 where the negative electrode film layer 12b is provided.

[0293] In some embodiments, a gap G is formed between the negative electrode film layer 12b and the positive electrode film layer 11b.

[0294] In some embodiments, a plurality of support portions 14 are provided on the side of the positive electrode sheet 11 facing the separator 13, a plurality of support portions 14 are provided on the side of the separator 13 facing the positive electrode sheet 11, and at least a part of the plurality of support portions 14 of the positive electrode sheet 11 facing the separator 13 is disposed opposite to at least a part of the plurality of support portions 14 of the separator 13 facing the positive electrode sheet 11.

[0295] Optionally, the negative electrode sheet 12 is not provided with a support portion.

[0296] As an example, separators 13 are provided on both sides of the positive electrode sheet 11. The separator 13 located inside the positive electrode sheet 11 is called the inner separator, and the separator 13 located outside the positive electrode sheet 11 is called the outer separator;

[0297] In some examples, a plurality of support portions 14 are provided on the side of the positive electrode sheet 11 facing the inner separator, a plurality of support portions 14 are provided on the side of the inner separator facing the positive electrode sheet 11, and at least a part of the plurality of support portions 14 of the positive electrode sheet 11 is disposed opposite to at least a part of the plurality of support portions 14 of the inner separator. For example, at least a part of the plurality of positive electrode protrusions 112 of the positive electrode sheet 11 is disposed opposite to the plurality of organic particles of the inner separator.

[0298] In some other examples, a plurality of support portions 14 are provided on one side of the positive electrode sheet 11 facing the outer separator, and a plurality of support portions 14 are provided on the side of the outer separator facing the positive electrode sheet 11. The plurality of support portions 14 of the positive electrode sheet 11 and the plurality of support portions 14 of the outer separator are at least partially oppositely arranged. For example, the plurality of positive protrusions 112 of the positive electrode sheet 11 and the plurality of organic particles of the outer separator are at least partially opposite.

[0299] In still some other examples, a plurality of support portions 14 are provided on both sides of the positive electrode sheet 11. A plurality of support portions 14 are provided on the side of the inner separator facing the positive electrode sheet 11, and a plurality of support portions 14 are provided on the side of the outer separator facing the positive electrode sheet 11. The plurality of support portions 14 of the positive electrode sheet 11 facing the inner separator and the plurality of support portions 14 of the inner separator facing the positive electrode sheet 11 are at least partially opposite, and the plurality of support portions 14 of the positive electrode sheet 11 facing the outer separator and the plurality of support portions 14 of the outer separator facing the positive electrode sheet 11 are at least partially opposite.

[0300] By arranging the plurality of support portions 14 of the positive electrode sheet 11 to face the plurality of support portions 14 of the separator 13, the plurality of support portions 14 of the positive electrode sheet 11 and the plurality of support portions 14 of the separator 13 can be at least partially abutted against each other to increase the gap G and provide more space for the expansion of the negative electrode sheet 12.

[0301] As an example, the embodiments of the present application can reduce the depth of the positive electrode recess 113 and the particle size of the organic particles, reduce the damage of the positive electrode sheet 11 during the stamping process, and improve the cycle life of the cylindrical battery cell 7.

[0302] In some embodiments, a plurality of support portions 14 are provided on the side of the negative electrode sheet 12 facing the separator 13, and a plurality of support portions 14 are provided on the side of the separator 13 facing the negative electrode sheet 12. At least a part of the plurality of support portions 14 of the negative electrode sheet 12 facing the separator 13 and the plurality of support portions 14 of the separator 13 facing the negative electrode sheet 12 are oppositely arranged.

[0303] Optionally, no support portion is provided on the positive electrode sheet 11.

[0304] As an example, separators 13 are provided on both sides of the negative electrode sheet 12. The separator 13 located inside the negative electrode sheet 12 is called the inner separator, and the separator 13 located outside the negative electrode sheet 12 is called the outer separator;

[0305] In some examples, a plurality of support portions 14 are provided on the side of the negative electrode sheet 12 facing the inner separator, and a plurality of support portions 14 are provided on the side of the inner separator facing the negative electrode sheet 12. The plurality of support portions 14 of the negative electrode sheet 12 and the plurality of support portions 14 of the inner separator are at least partially oppositely arranged. For example, the plurality of negative protrusions 122 of the negative electrode sheet 12 and the plurality of organic particles of the inner separator are at least partially opposite.

[0306] In some other examples, a plurality of support portions 14 are provided on the side of the negative electrode sheet 12 facing the outer separator, a plurality of support portions 14 are provided on the side of the outer separator facing the negative electrode sheet 12, and at least a part of the plurality of support portions 14 of the negative electrode sheet 12 and the plurality of support portions 14 of the outer separator are oppositely arranged. For example, at least a part of the plurality of negative protrusions 122 of the negative electrode sheet 12 and the plurality of organic particles of the outer separator are oppositely arranged.

[0307] In still some other examples, a plurality of support portions 14 are provided on both sides of the negative electrode sheet 12. A plurality of support portions 14 are provided on the side of the inner separator facing the negative electrode sheet 12, and a plurality of support portions 14 are provided on the side of the outer separator facing the negative electrode sheet 12. At least a part of the plurality of support portions 14 of the negative electrode sheet 12 facing the inner separator and the plurality of support portions 14 of the inner separator facing the negative electrode sheet 12 are oppositely arranged, and at least a part of the plurality of support portions 14 of the negative electrode sheet 12 facing the outer separator and the plurality of support portions 14 of the outer separator facing the negative electrode sheet 12 are oppositely arranged.

[0308] By arranging the plurality of support portions 14 of the negative electrode sheet 12 to face the plurality of support portions 14 of the separator 13, at least a part of the plurality of support portions 14 of the negative electrode sheet 12 and the plurality of support portions 14 of the separator 13 can be abutted against each other to increase the gap G and provide more space for the expansion of the negative electrode sheet 12.

[0309] As an example, the embodiments of the present application can reduce the depth of the negative electrode concave portion 123 and the particle size of the organic particles P, reduce the damage of the negative electrode sheet 12 during the stamping process, and improve the cycle life of the cylindrical battery cell 7.

[0310] In some embodiments, a plurality of support portions 14 are provided on the side of the negative electrode sheet 12 facing the positive electrode sheet 11, a plurality of support portions 14 are provided on the side of the positive electrode sheet 11 facing the negative electrode sheet 12, and at least a part of the plurality of support portions 14 of the negative electrode sheet 12 facing the positive electrode sheet 11 and the plurality of support portions 14 of the positive electrode sheet 11 facing the negative electrode sheet 12 are oppositely arranged.

[0311] Optionally, the separator 13 is not provided with support portions.

[0312] In some examples, a plurality of support portions 14 are provided on the outer side of the positive electrode sheet 11, and a plurality of support portions 14 are provided on the inner side of the negative electrode sheet 12. The plurality of support portions 14 on the outer side of the positive electrode sheet 11 and the plurality of support portions 14 on the inner side of the negative electrode sheet 12 are arranged to face each other and overlap in the radial direction.

[0313] In some examples, a plurality of support portions 14 are provided on the inner side of the positive electrode sheet 11, and a plurality of support portions 14 are provided on the outer side of the negative electrode sheet 12. The plurality of support portions 14 on the inner side of the positive electrode sheet 11 and the plurality of support portions 14 on the outer side of the negative electrode sheet 12 are arranged to face each other and overlap in the radial direction.

[0314] In some examples, a plurality of support portions 14 are provided on both the inner and outer sides of the positive electrode sheet 11, and a plurality of support portions 14 are provided on both the inner and outer sides of the negative electrode sheet 12; the plurality of support portions 14 on the outer side of the positive electrode sheet 11 are arranged facing the plurality of support portions 14 on the inner side of the negative electrode sheet 12 and overlap in the radial direction, and the plurality of support portions 14 on the inner side of the positive electrode sheet 11 are arranged facing the plurality of support portions 14 on the outer side of the negative electrode sheet 12 and overlap in the radial direction.

[0315] By arranging the plurality of support portions 14 of the negative electrode sheet 12 facing the plurality of support portions 14 of the positive electrode sheet 11, the plurality of support portions 14 of the negative electrode sheet 12 and the plurality of support portions 14 of the positive electrode sheet 11 can support each other to increase the gap G and provide more space for the expansion of the negative electrode sheet 12.

[0316] As an example, embodiments of the present application can reduce the depth of the negative electrode concave portion 123 and the depth of the positive electrode concave portion 113, reduce the damage to the positive electrode sheet 11 and the negative electrode sheet 12 during the stamping process, and improve the cycle life of the cylindrical battery cell 7.

[0317] In some embodiments, the positive electrode sheet 11, the negative electrode sheet 12, and the separator 13 are all provided with a plurality of support portions 14.

[0318] Optionally, a plurality of support portions 14 are provided on both sides of the separator 13.

[0319] Optionally, a plurality of support portions 14 are provided on the outer side of the positive electrode sheet 11, and a plurality of support portions 14 are provided on the inner side of the negative electrode sheet 12; alternatively, a plurality of support portions 14 are provided on the inner side of the positive electrode sheet 11, and a plurality of support portions 14 are provided on the outer side of the negative electrode sheet 12.

[0320] Figure 15 A cross-sectional view of the positive electrode sheet provided in other embodiments of the present application.

[0321] Refer to Figure 15 , in some embodiments, the positive electrode sheet 11 includes a positive electrode base portion 111 and a plurality of support portions 14, and the support portion 14 includes organic particles provided on the positive electrode base portion 111.

[0322] The organic particles P may protrude from the positive electrode base portion 111 as a whole. Alternatively, a part of the organic particles is embedded in the positive electrode base portion 111, and the other part protrudes from the positive electrode base portion 111.

[0323] The organic particles P of the positive electrode sheet 11 can support the negative electrode sheet 12 to increase the gap G and provide space for the expansion of the negative electrode sheet 12.

[0324] In some embodiments, the positive electrode base 111 includes a positive electrode current collector 11a, a positive electrode film layer 11b, and an inorganic particle layer P3. The positive electrode film layer 11b is disposed on the surface of the positive electrode current collector 11a, and the inorganic particle layer P3 is coated on the surface of the positive electrode film layer 11b facing away from the positive electrode current collector. The organic particle P at least partially protrudes from the inorganic particle layer P3.

[0325] The positive electrode film layer 11b includes a positive electrode active material, and the inorganic particle layer P3 includes a plurality of inorganic particles.

[0326] In some embodiments, a part of the organic particle P is embedded in the inorganic particle layer P3, and a part protrudes from the inorganic particle layer P3.

[0327] In some embodiments, the positive electrode sheet 11 includes a positive electrode particle coating 11c disposed on the surface of the positive electrode film layer 11b. The positive electrode particle coating 11c includes the inorganic particle layer P3 and a plurality of organic particles P.

[0328] In some examples, inorganic particles can be first coated on the positive electrode film layer 11b to form the inorganic particle layer P3, and then a plurality of organic particles can be coated on the inorganic particle layer P3. In other examples, the inorganic particles and the organic particles can be first mixed and then coated together on the positive electrode film layer 11b.

[0329] As an example, the positive electrode particle coating 11c does not include a positive electrode active material.

[0330] In some embodiments, the plurality of organic particles P includes a first organic particle P1 and a second organic particle P2, and the number average particle size of the first organic particle P1 is greater than the number average particle size of the second organic particle P2.

[0331] Figure 16 A cross-sectional schematic view of a negative electrode sheet provided in other embodiments of the present application.

[0332] Refer to Figure 16 , in some embodiments, the negative electrode sheet 12 includes a negative electrode base 121 and a plurality of support portions 14. The support portions 14 include organic particles P disposed on the negative electrode base 121.

[0333] The organic particle P can protrude entirely from the negative electrode base 121. Alternatively, a part of the organic particle is embedded in the negative electrode base 121, and the other part protrudes from the negative electrode base 121.

[0334] The organic particle P of the negative electrode sheet 12 can support the positive electrode sheet 11 to increase the gap G and provide space for the expansion of the negative electrode sheet 12.

[0335] In some embodiments, the negative electrode base 121 includes a negative electrode current collector 12a, a negative electrode film layer 12b, and an inorganic particle layer P3. The negative electrode film layer 12b is disposed on the surface of the negative electrode current collector 12a, and the inorganic particle layer P3 is coated on the surface of the negative electrode film layer 12b facing away from the negative electrode current collector 12a. The organic particles P at least partially protrude from the inorganic particle layer P3.

[0336] The negative electrode film layer 12b includes negative electrode active materials, and the inorganic particle layer P3 includes a plurality of inorganic particles.

[0337] In some embodiments, a part of the organic particles P is embedded in the inorganic particle layer P3, and a part protrudes from the inorganic particle layer P3.

[0338] In some embodiments, the negative electrode sheet 12 includes a negative electrode particle coating 12c disposed on the surface of the negative electrode film layer 12b. The negative electrode particle coating 12c includes the inorganic particle layer P3 and a plurality of organic particles P.

[0339] In some examples, inorganic particles can be first coated on the negative electrode film layer 12b to form the inorganic particle layer P3, and then a plurality of organic particles can be coated on the inorganic particle layer P3. In other examples, the inorganic particles and the organic particles can be first mixed and then coated together on the negative electrode film layer 12b.

[0340] As an example, the negative electrode particle coating 12c does not include negative electrode active materials.

[0341] In some embodiments, the plurality of organic particles P include a first organic particle P1 and a second organic particle P2, and the number average particle size of the first organic particle P1 is greater than the number average particle size of the second organic particle P2.

[0342] Figure 17 It is a partial cross-sectional view of an electrode assembly of a cylindrical battery cell provided in other embodiments of the present application. Figure 17 It shows a ring of positive electrode sheets, a ring of negative electrode sheets, and a ring of separators.

[0343] Referring to Figure 6 and 17 , in some embodiments, the radial dimension of the portion of the gap G near the winding start end E1 is greater than or equal to the radial dimension of the portion of the gap G near the winding end E2.

[0344] In the embodiments of the present application, the radial dimensions of different portions of the gap G along the winding direction V are compared in the same cross-section perpendicular to the axial direction Z.

[0345] The "portion of the gap G near the winding start end E1" does not require extending from the winding start end E1. As an example, the "portion of the gap G near the winding start end E1" can extend from a position 1-5 turns away from the winding start end in the winding direction V.

[0346] The portion of the gap G close to the winding end E2 does not require extending along the winding direction V to the winding end E2. As an example, the end of the portion of the gap G close to the winding end E2 along the winding direction V may be 1-5 turns away from the winding end E2.

[0347] In an embodiment of the present application, the portion of the gap G close to the winding start end E1 has a larger radial dimension to provide more expansion space for the negative electrode sheet 12 in the middle of the electrode assembly 10, reduce the risk of the middle part of the electrode assembly 10 collapsing due to expansion, and improve the cycling performance of the cylindrical battery cell 7.

[0348] In some embodiments, the gap G extends along the winding direction V and winds for n turns, and each turn is defined as a winding turn, where n≥20. The average value of the radial dimensions of the 5th to 9th winding turns is greater than the average value of the radial dimensions of the (n-9)th to (n-5)th winding turns.

[0349] It should be noted here that n does not require to be an integer. In other words, the 1st to (n-1)th winding turns are all complete turns; the portion from the end of the (n-1)th winding turn to the winding end E2 can be a complete turn or not, such as 1 / 4 turn, 1 / 2 turn or 3 / 4 turn.

[0350] In an embodiment of the present application, the portion of the gap G close to the winding start end E1 has a larger radial dimension to provide more expansion space for the negative electrode sheet 12 in the middle of the electrode assembly 10, reduce the risk of the middle part of the electrode assembly 10 collapsing due to expansion, and improve the cycling performance of the cylindrical battery cell 7.

[0351] In some embodiments, the radial dimension of at least a part of the gap G gradually decreases along the winding direction V.

[0352] The radial dimension of the gap G changes smoothly, reducing the sudden change of the radial dimension of the gap G, reducing the stress concentration of the negative electrode sheet 12, and improving the cycling performance of the cylindrical battery cell 7.

[0353] Figure 18 A partial cross-sectional view of the electrode assembly of the cylindrical battery cell provided for some other embodiments of the present application.

[0354] Referring to Figure 18 , in some embodiments, the gap G includes a middle region C1 and two end regions C2 arranged along the axial direction Z of the cylindrical battery cell. The middle region C1 is located between the two end regions C2, and the radial dimension of the middle region C1 is smaller than the radial dimension of the end regions C2.

[0355] In the embodiment of the present application, the radial dimensions of the middle region C1 and the end regions C2 are compared in a cross-section parallel to the axial direction Z of one winding turn.

[0356] The gap G has a first end E7 and a second end E8 that are oppositely arranged along the axial direction Z; the dimension of the gap G along the axial direction Z is defined as L, that is, the distance between the first end E7 and the second end E8 on the axial direction Z is L.

[0357] The end region C2 is a region having a certain dimension in the axial direction Z. One end region C2 is a region extending from the first end E7 towards the second end E8 to a length L1, and the other end region C2 is a region extending from the second end E8 towards the first end E7 for a length L1; the middle region C1 includes a region extending from the middle cross-section S towards the first end E7 to a length L2 and a region extending from the middle cross-section S towards the second end E8 to a length L2. The middle cross-section S is a cross-section perpendicular to the axial direction Z; on the axial direction Z, the distance between the middle cross-section S and the first end E7 is equal to the distance between the middle cross-section S and the second end E8.

[0358] Exemplarily, L1 / L is 0.1 - 0.3, and can be optionally 0.2. Exemplarily, L2 / L is 0.03 - 0.2, and can be optionally 0.1.

[0359] Exemplarily, L1 can be 20 mm, and L2 can be 5 mm.

[0360] Exemplarily, the minimum radial dimension of the end region C2 is greater than the maximum radial dimension of the middle region C1.

[0361] In the embodiment of the present application, the end region C2 has a relatively large radial dimension, so as to facilitate the electrolyte to enter the gap G, improve the wetting effect of the electrolyte on the electrode sheet, and enhance the cycling performance of the cylindrical battery cell 7.

[0362] In some embodiments, the radial dimension of the middle region is 5 μm - 60 μm, and can be optionally 10 μm - 30 μm.

[0363] In some embodiments, the gap G further includes a transition region C3 connecting the middle region C1 and the end region C2.

[0364] In some embodiments, in the direction from the end region C2 to the middle region C1, the radial dimension of the gap G gradually decreases, so as to reduce the sudden change of the radial dimension of the gap G, reduce the stress concentration of the negative electrode sheet 12, and improve the cycling performance of the cylindrical battery cell 7.

[0365] Figure 19 For Figure 4 The sectional view schematic diagram of the battery cell shown; Figure 20 For Figure 19 The enlarged schematic diagram at the circular frame.

[0366] Refer to Figure 4 、 Figure 5 、 Figure 19 AndFigure 20 , in some embodiments, one of the positive electrode sheet 11 and the negative electrode sheet 12 includes a first tab 10a, and the other includes a second tab 10b. In other words, one of the first tab 10a and the second tab 10b is a positive tab, and the other is a negative tab.

[0367] The first tab 10a and the second tab 10b can be located at the same end of the electrode assembly 10 along the axial direction Z, or can be respectively located at both ends of the electrode assembly 10 along the axial direction Z.

[0368] In some embodiments, the portion of the positive electrode sheet 11 having the positive electrode film layer, the portion of the negative electrode sheet 12 having the negative electrode film layer, and the separator 13 constitute the electrode main body 10c of the electrode assembly 10. The first tab 10a and the second tab 10b are led out from one end of the electrode main body 10c, or are respectively led out from both ends of the electrode main body 10c.

[0369] In some embodiments, the first tab 10a is wound into multiple turns along the winding direction V. Optionally, the end of the first tab 10a is bent by a flattening or smoothing process, and a multi-layer structure stacked in the axial direction Z is formed.

[0370] In some embodiments, the second tab 10b is wound into multiple turns along the winding direction V. Optionally, the end of the second tab 10b is bent by a flattening or smoothing process, and a multi-layer structure stacked in the axial direction Z is formed.

[0371] In some embodiments, the cylindrical battery cell 7 includes a first electrode lead-out portion 7a and a second electrode lead-out portion 7b. The first electrode lead-out portion 7a is electrically connected to the first tab 10a, and the second electrode lead-out portion 7b is electrically connected to the second tab 10b.

[0372] The first electrode lead-out portion 7a and the second electrode lead-out portion 7b are insulated from each other.

[0373] The first electrode lead-out portion 7a and the second electrode lead-out portion 7b are used to connect to an external circuit to realize charging or discharging of the cylindrical battery cell 7. Exemplarily, when a plurality of cylindrical battery cells 7 are assembled into a group, the first electrode lead-out portion 7a and the second electrode lead-out portion 7b are used to connect to a busbar component.

[0374] The first electrode lead-out portion 7a can be an electrode terminal 30 provided on the outer shell 20. The electrode terminal 30 is independently formed with the outer shell 20 and is assembled together during the production process of the cylindrical battery cell 7. As an example, the electrode terminal 30 is insulatingly provided on the end cap 22 or the housing 21.

[0375] Alternatively, the first electrode lead-out portion 7a may also be part of the housing 20. For example, the first electrode lead-out portion 7a may be the end cap 22 of the housing 20, or the first electrode lead-out portion 7a is the end wall 211 of the housing 21 opposite to the end cap 22.

[0376] The second electrode lead-out portion 7b may be the electrode terminal 30 provided on the housing 20. Alternatively, the second electrode lead-out portion 7b may be part of the housing 20. For example, the second electrode lead-out portion 7b may be the end cap 22 of the housing 20, or the second electrode lead-out portion 7b is the end wall 211 of the housing 21 opposite to the end cap 22.

[0377] In some embodiments, along the axial direction Z of the cylindrical battery cell, the first electrode lead-out portion 7a and the second electrode lead-out portion 7b are located on the same side of the electrode assembly 10.

[0378] When a plurality of cylindrical battery cells 7 are assembled into a group, the first electrode lead-out portions 7a and the second electrode lead-out portions 7b of the plurality of cylindrical battery cells 7 may be arranged on the same side, which is convenient for realizing the connection between the bus bar component and the first electrode lead-out portion 7a and the second electrode lead-out portion 7b, and simplifies the battery structure.

[0379] In some embodiments, the housing 20 includes a housing body 21 and an end cap 22. The housing body 21 includes a side wall 212 and an end wall 211 formed integrally. The end wall 211 and the end cap 22 are opposite to each other along the axial direction Z of the cylindrical battery cell, and the end cap 22 is sealingly connected to the side wall 212.

[0380] The end cap 22 may be insulated from the side wall 212 or may be electrically connected.

[0381] One end of the housing body 21 away from the end wall 211 has an opening, and the end cap 22 covers the opening of the housing body 21.

[0382] In some embodiments, one of the positive electrode sheet 11 and the negative electrode sheet 12 includes a first tab 10a, and the other includes a second tab 10b. The cylindrical battery cell 7 further includes an electrode terminal 30 insulatedly disposed on the end wall 211. One of the first tab 10a and the second tab 10b is electrically connected to the electrode terminal 30, and the other is electrically connected to the end wall 211.

[0383] As an example, the first tab 10a is electrically connected to the electrode terminal 30, and the second tab 10b is electrically connected to the end wall 211. The second tab 10b may be directly connected to the end wall 211 or may be indirectly connected to the end wall 211 through the end cap 22, the side wall 212 or other components.

[0384] One of the electrode terminal 30 and the end wall 211 serves as the first electrode lead-out portion 7a, and the other serves as the second electrode lead-out portion 7b.

[0385] The electrode terminal 30 and the end wall 211 can serve as the two exposed electrodes of the cylindrical battery cell 7. The electrode terminal 30 and the end wall 211 are located on the same side, which is beneficial to assembling multiple cylindrical battery cells 7 into a group and simplifies the battery structure.

[0386] In some embodiments, the cylindrical battery cell 7 further includes a first current collector member 40. The first current collector member 40 is located on the side of the first tab 10a facing the end wall 211 and is connected to the first tab 10a. The electrode terminal 30 abuts against and is connected to the surface of the first current collector member 40 facing the end wall 211.

[0387] The first current collector member 40 can play a role in transfer and realize the electrical connection between the first tab 10a and the electrode terminal 30.

[0388] In some embodiments, the first current collector member 40 is circular.

[0389] In some embodiments, a terminal recess 31 is provided on the side of the electrode terminal 30 facing the first current collector member 40. The bottom wall of the terminal recess 31 is welded to the first current collector member 40.

[0390] By providing the terminal recess 31, the thickness of the bottom wall of the terminal recess 31 can be reduced, the power required for welding the electrode terminal 30 and the first current collector member 40 from the outside can be reduced, the risk of particles generated by welding falling into the housing 20 can be reduced, and the reliability of the cylindrical battery cell 7 can be improved.

[0391] By providing the terminal recess 31 inside the electrode terminal 30, the internal space of the cylindrical battery cell 7 can also be increased.

[0392] In some embodiments, a terminal recess 31 is provided on the side of the electrode terminal 30 facing away from the first current collector member 40.

[0393] In some embodiments, a terminal recess 31 is provided on the side of the electrode terminal 30 facing the first current collector member 40, and another terminal recess 31 is provided on the side of the electrode terminal 30 facing away from the first current collector member 40; corresponding portions of the bottom surfaces of the two terminal recesses 31 are welded to the first current collector member 40.

[0394] In some embodiments, a through hole 32 is provided in the bottom wall of the terminal recess 31. The through hole 32 can be used for injecting electrolyte.

[0395] In some embodiments, the cylindrical battery cell 7 further includes a cover plate 50. The cover plate 50 is connected to the electrode terminal 30 and is used to separate the through hole 32 from the external space of the cylindrical battery cell 7.

[0396] In some embodiments, at least a part of the cover plate 50 is received in the terminal recess 31. In some embodiments, the first electrode lead-out portion includes the cover plate 50 and the electrode terminal 30.

[0397] In some embodiments, the electrode terminal 30 is riveted to the end wall 211.

[0398] In some embodiments, the first tab 10a is located at one end of the electrode assembly 10 facing the end wall 211, and the second tab 10b is located at one end of the electrode assembly 10 facing the end cap 22. The cylindrical battery cell 7 further includes a second current collector member 60 connected to the second tab 10b; the second current collector member 60 is connected to at least one of the end cap 22 and the side wall 212.

[0399] In some examples, the second current collector member 60 is connected to the end cap 22, and the end cap 22 is electrically connected to the side wall 212. The second tab 10b is electrically connected to the end wall 211 through the second current collector member 60, the end cap 22, and the side wall 212.

[0400] In other examples, the second current collector member 60 is connected to the side wall 212. The second tab 10b is electrically connected to the end wall 211 through the second current collector member 60 and the side wall 212. Optionally, the end cap 22 and the side wall 212 are insulated from each other.

[0401] In some embodiments, the housing 20 includes a side wall 212 surrounding the electrode assembly 10, and the thickness of the side wall 212 is 0.3 mm to 1.5 mm. The material of the side wall 212 includes steel.

[0402] As an example, the thickness of the side wall 212 is 0.3 mm, 0.31 mm, 0.32 mm, 0.33 mm, 0.35 mm, 0.38 mm, 0.40 mm, 0.42 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, 1 mm, 1.05 mm, 1.1 mm, 1.15 mm, 1.2 mm, 1.3 mm, 1.35 mm, 1.4 mm, 1.45 mm, or 1.5 mm.

[0403] In the embodiments of the present application, the thickness of the side wall 212 has the meaning well known in the art, and can be detected by devices and methods well known in the art. For example, a micrometer or a vernier caliper can be used for measurement.

[0404] As an example, the material of the side wall 212 includes stainless steel.

[0405] By providing the gap G in this application, the expansion force exerted by the electrode assembly 10 on the side wall 212 can be reduced. Therefore, the steel side wall 212 can have a thickness less than or equal to 1.5 mm, thereby increasing the energy density of the cylindrical battery cell 7. The thickness of the steel side wall 212 is greater than or equal to 0.3 mm to reduce the risk of deformation and rupture of the side wall 212 under the expansion force of the electrode assembly 10 and improve the reliability of the cylindrical battery cell 7.

[0406] The mechanical strength of the side wall 212 is relatively high and it is not easily deformed. When used in conjunction with the silicon-containing negative electrode sheet 12, it is more conducive to improving the energy density of the battery cell while making the battery cell have excellent service reliability.

[0407] In some embodiments, the thickness of the side wall 212 is from 0.3 mm to 1.2 mm.

[0408] In some embodiments, the thickness of the side wall 212 is from 0.3 mm to 0.9 mm, and can be optionally from 0.3 mm to 0.6 mm.

[0409] In some embodiments, the areal capacity density of the negative electrode sheet is greater than or equal to 3.2 mAh / cm 2 , the base material of the side wall 212 includes steel, and the thickness of the side wall 212 is from 0.3 mm to 0.9 mm. When the negative electrode sheet with the above areal capacity density and the side wall 212 with the above thickness are used in combination, while increasing the energy density of the battery cell 7, the battery cell 7 has excellent service reliability and is beneficial to the improvement of the cycling performance.

[0410] In some embodiments, the material of the end wall 211 is the same as that of the side wall 212.

[0411] In some embodiments, the material of the end cap 22 is steel.

[0412] In some embodiments, the height of the outer shell 20 is 1.3 times to 4 times the diameter of the outer shell 20. Exemplarily, the height of the outer shell 20 can be the dimension of the outer shell 20 along the axial direction Z.

[0413] Optionally, the height of the outer shell 20 is 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, 2.0 times, 2.1 times, 2.2 times, 2.3 times, 2.4 times, 2.5 times, 2.6 times, 2.7 times, 2.8 times, 2.9 times, 3.0 times, 3.1 times, 3.2 times, 3.3 times, 3.4 times, 3.5 times, 3.6 times, 3.7 times, 3.8 times, 3.9 times or 4.0 times the diameter of the outer shell 20.

[0414] When the outer shell 20 meets the above size requirements, the structural stability of the outer shell 20 can be relatively high, which can improve the service reliability of the cylindrical battery cell 7.

[0415] In some embodiments, the height of the outer shell 20 is 1.5 to 2.5 times the diameter of the outer shell 20.

[0416] In some embodiments, the height of the outer shell 20 is 50 mm to 150 mm. For example, the height of the outer shell 20 is 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm, 80 mm, 85 mm, 90 mm, 95 mm, 100 mm, 105 mm, 110 mm, 115 mm, 120 mm, 125 mm, 130 mm, 135 mm, 140 mm, 145 mm, or 150 mm.

[0417] Optionally, the height of the outer shell 20 is 60 mm - 100 mm.

[0418] In some embodiments, the diameter of the outer shell 20 is 45 mm to 80 mm. For example, the diameter of the outer shell 20 is 45 mm, 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm, or 80 mm.

[0419] Optionally, the diameter of the outer shell 20 is 45 mm to 60 mm.

[0420] Figure 21 A partial cross-sectional schematic diagram of a battery cell provided for other embodiments of the present application.

[0421] Referring to Figure 21 , in some embodiments, both the first tab 10a and the second tab 10b are located at one end of the electrode assembly 10 facing the end wall 211. The first tab 10a and the second tab 10b can share space in the axial direction Z, thereby improving space utilization and energy density.

[0422] In some embodiments, the cylindrical battery cell 7 includes two electrode terminals 30 disposed on the end wall 211, and the first tab 10a and the second tab 10b are respectively electrically connected to the two electrode terminals 30. The two electrode terminals 30 are respectively a first electrode lead-out portion 7a and a second electrode lead-out portion 7b.

[0423] Optionally, the cylindrical battery cell 7 includes a first current collector member 40 and a second current collector member 60. The first current collector member 40 connects the first tab 10a and one electrode terminal 30, and the second current collector member 60 connects the second tab 10b and the other electrode terminal 30.

[0424] In other embodiments, the cylindrical battery cell includes one electrode terminal disposed on the end wall, the first tab is electrically connected to the electrode terminal, and the second tab is electrically connected to the end wall.

[0425] In some embodiments, the projection of the first tab 10a along the axial direction Z is fan-shaped.

[0426] In some embodiments, the projection of the second tab 10b along the axial direction Z is fan-shaped.

[0427] According to some embodiments of the present application, the present application also provides a battery, including a plurality of cylindrical battery cells 7 as described in any of the above embodiments.

[0428] According to some embodiments of the present application, the present application also provides an electrical device, including the cylindrical battery cell 7 as described in any of the above embodiments. The cylindrical battery cell 7 is used to supply electrical energy to the electrical device. The electrical device can be any of the aforementioned devices or systems using the cylindrical battery cell 7.

[0429] Referring to Figures 4 to 9 , an embodiment of the present application provides a cylindrical battery cell 7, which includes a housing 20, an electrode assembly 10, an electrode terminal 30, a first current collector member 40, and a second current collector member 60.

[0430] The housing 20 includes a housing body 21 and an end cap 22. The housing body 21 includes a side wall 212 and an end wall 211 formed integrally. The end wall 211 and the end cap 22 are opposite to each other along the axial direction Z of the cylindrical battery cell. The end cap 22 is welded to the side wall 212.

[0431] The electrode terminal 30 is disposed on the end wall 211 in an insulating manner.

[0432] At least a part of the electrode assembly 10 is accommodated in the housing 20. The electrode assembly 10 includes a positive electrode sheet 11, a negative electrode sheet 12, and a separator 13. The positive electrode sheet 11, the negative electrode sheet 12, and the separator 13 are wound. The separator 13 separates the positive electrode sheet 11 and the negative electrode sheet 12.

[0433] One end of the positive electrode sheet 11 facing the end wall 211 has a first tab 10a. The first current collector member 40 connects the electrode terminal 30 and the first tab 10a. One end of the negative electrode sheet 12 facing the end cap 22 has a second tab 10b. The second current collector member 60 connects the first tab 10a and the end cap 22.

[0434] The separator 13 includes a base film 13a and a coating 13b provided on at least one surface of the base film 13a. The coating 13b includes an inorganic particle layer P3 and a plurality of organic particles P. The organic particles P at least partially protrude from the inorganic particle layer P3. The organic particles P are used to support the positive electrode sheet 11 or the negative electrode sheet 12 to form a gap G between the positive electrode sheet 11 and the negative electrode sheet 12.

[0435] Embodiment

[0436] The following examples more specifically describe the content disclosed in the embodiments of the present application. These examples are only for illustrative purposes, because various modifications and changes within the scope of the content disclosed in the embodiments of the present application are obvious to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further treatment, and the instruments used in the examples are all commercially available.

[0437] Example 1

[0438] 1. Preparation of the positive electrode sheet

[0439] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer. The positive electrode film layer is located on both sides of the positive electrode current collector. The positive electrode current collector is aluminum foil. The positive electrode film layer is a film layer formed by uniformly coating a positive electrode slurry (the solvent is N-methylpyrrolidone NMP) on the surface of the aluminum foil of the positive electrode current collector and then drying and cold pressing. The positive electrode film layer includes a positive electrode active material, conductive agent carbon black (Super P), and binder polyvinylidene fluoride (PVDF) with a weight ratio of 97:1:2.

[0440] The positive electrode active material includes a layered transition metal oxide with the molecular formula LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811).

[0441] 2. Preparation of the negative electrode sheet

[0442] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer. The negative electrode film layer is located on both sides of the negative electrode current collector. The negative electrode current collector is copper foil. The negative electrode film layer is a film layer formed by uniformly coating a negative electrode slurry (the solvent is deionized water) on the surface of the copper foil of the negative electrode current collector and then drying and cold pressing. The negative electrode film layer includes a silicon-based material (specifically silicon oxide), graphite, conductive agent carbon black, conductive agent carbon nanotubes, and binder polyacrylic acid with a weight ratio of 12.6:82.4:1.9:0.1:3;

[0443] The areal density of the negative electrode film layer is 9.0 mg / cm 2 , the porosity is 22.1%, and the tap density is 1.7 g / cm 3 .

[0444] 3. Separator

[0445] Provide a PE (polyethylene)-based film.

[0446] Preparation of the coating slurry: Mix inorganic particles aluminum oxide (Al2O3), first organic particles vinylidene fluoride - hexafluoropropylene copolymer (number average molecular weight of 550,000), second organic particles styrene - vinyl acetate - pyrrolidone copolymer (number average molecular weight of 80,000), dispersant sodium carboxymethyl cellulose (CMC - Na), and wetting agent organosilicon - modified polyether evenly in an appropriate amount of deionized water solvent according to a dry weight ratio of 70:20:8:1:1 to obtain a coating slurry with a solid content of 38% (by weight). Among them, the volume average particle size Dv50 of the inorganic particles aluminum oxide (Al2O3) is 1 μm, the first organic particles are secondary particles with a number average particle size of 15 μm, and the second organic particles are primary particles with a number average particle size of 2 μm.

[0447] Coat the coating slurry on two surfaces of the PE base film, and obtain a separator through processes such as drying and slitting.

[0448] 4. Preparation of the electrolyte

[0449] The electrolyte includes organic solvents and lithium salts. Mix ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 1:1:1 to obtain the organic solvents. Then dissolve the fully dried lithium salt LiPF6 in the mixed organic solvents to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0450] 5. Preparation of the cylindrical battery cell

[0451] Stack the above - mentioned positive electrode sheet, separator, and negative electrode sheet in sequence, with the separator between the positive electrode sheet and the negative electrode sheet to play an isolation role. Wind the positive electrode sheet, separator, and negative electrode sheet to obtain an electrode assembly; place the electrode assembly in a cylindrical - shaped outer shell, inject the electrolyte after drying, and obtain a cylindrical battery cell through processes such as vacuum packaging, standing, forming, and shaping. Among them, the electrode assembly is in a cylindrical shape, the outer shell is in a cylindrical shape, the outer shell includes a shell body and an end cover, the shell body includes a side wall and an end wall formed integrally, the side wall surrounds the electrode assembly, and the end cover and the end wall are opposite along the axis of the outer shell. The diameter of the cylindrical battery cell is 46 mm and the height is 95 mm.

[0452] Performance Test

[0453] 1. Expansion volume test of the battery cell

[0454] Immerse the cylindrical battery cell in the charged state of 0% in silicone oil and weigh its mass as m0.

[0455] Immerse the cylindrical battery cell in the charged state of 100% in silicone oil and weigh its mass as m1.

[0456] The density of silicone oil is ρ 硅油If so, the volume change ΔV of the cylindrical battery cell between 100% state of charge and 0% state of charge is: ΔV = (m0 - m1) / ρ 硅油 If ΔV is used to evaluate the usage reliability of the cylindrical battery cell, the smaller ΔV is, the smaller the volume expansion of the cylindrical battery cell is, and the higher the usage reliability is; the larger ΔV is, the larger the volume expansion of the cylindrical battery cell is, and the worse the usage reliability is.

[0457] Among them, at 25°C, the above-mentioned cylindrical battery cell is discharged at 0.33C to 2.5V, and then discharged at 0.1C to 2.5V. At this time, the cylindrical battery cell is in the 0% state of charge. At 25°C, the cylindrical battery cell is charged at 0.33C to 4.25V, and then charged at 0.1C to 4.25V. At this time, the cylindrical battery cell is in the 100% state of charge.

[0458] 2. Energy density test of the cylindrical battery cell

[0459] Under a constant voltage (4.25V in Example 1), multiply the first-week discharge capacity (Ah) by the ratio of the discharge voltage to the mass of the cylindrical battery cell.

[0460] Energy density = first-week discharge capacity (Ah) × discharge voltage (4.25V) / mass of the cylindrical battery cell (kg). The first-week discharge capacity is tested according to the following steps: At 45°C, the above-prepared cylindrical battery cell is fully charged at 1C and then fully discharged at 1C. This is a cycle of charge and discharge process. Record the discharge capacity at this time, which is the first-week discharge capacity.

[0461] 3. Cycle performance test of the battery

[0462] At 45°C, the above-prepared cylindrical battery cell is fully charged at 1C and then fully discharged at 1C. This is a cycle of charge and discharge process. Record the discharge capacity at this time, which is the first-week discharge capacity. The cylindrical battery cell is subjected to cycle charge and discharge tests according to the above method. Record the discharge capacity after each cycle until the discharge capacity of the cylindrical battery cell decays to 80% of the initial discharge capacity. Use the number of cycles at this time to characterize the cycle performance of the cylindrical battery cell. The higher the number of cycles of the cylindrical battery cell, the better the cycle performance.

[0463] Examples 2 - 5

[0464] Battery cells are prepared using a method similar to that of Example 1. Different from Example 1, the preparation of the negative electrode sheet in Examples 2 - 5 includes the following steps:

[0465] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer. The negative electrode film layer is located on both sides of the negative electrode current collector. The negative electrode current collector is a copper foil. The negative electrode film layer is a film layer formed by uniformly coating a negative electrode slurry (with deionized water as the solvent) on the surface of the negative electrode current collector copper foil, followed by drying and cold pressing. The negative electrode film layer includes a silicon-based material (specifically silicon oxide), graphite, conductive agent carbon black, conductive agent carbon nanotubes, and binder polyacrylic acid; and the mass content and capacity surface density of silicon element are adjusted.

[0466] Examples 6 - 9

[0467] The battery cells were prepared using a method similar to that of Example 1. The difference from Example 1 is that the thickness of the side wall was adjusted in Examples 6 - 9.

[0468] The test results of each example are shown in Table 1.

[0469] Table 1

[0470]

[0471] Referring to Table 1, introducing silicon into the negative electrode active material can significantly improve the energy density of the cylindrical battery cell. By setting organic particles in the separator, a gap can be formed between the positive electrode sheet and the negative electrode sheet, and the gap can provide space for the expansion of the negative electrode sheet. Referring to Table 1, the expansion volume of the cylindrical battery cell is less than or equal to 0.5 mL, and the number of cycles of the cylindrical battery cell is greater than or equal to 800. The cylindrical battery cell has good reliability and cycling performance.

[0472] Referring to Examples 1 - 5, by adjusting the mass content of silicon element, the capacity surface density can be synchronously adjusted, which is beneficial to taking into account the improvement of the cycling performance and energy density of the battery cell. The gap can provide space for the expansion of the negative electrode sheet. When the silicon element content reaches 19%, the expansion volume of the cylindrical battery cell is less than or equal to 0.5 mL, and the number of cycles of the cylindrical battery cell is greater than or equal to 800.

[0473] Referring to Example 1 and Examples 6 - 9, by adjusting the thickness of the side wall and cooperating with the mass content of silicon element, it is beneficial to take into account the improvement of the cycling performance and energy density of the battery cell, and the volume expansion of the battery cell is small. The side wall made of steel has high mechanical strength, can effectively improve the volume expansion problem, and can also take into account the improvement of the cycling performance and energy density of the battery cell.

[0474] It should be noted that, without conflict, the embodiments and features in the embodiments of the present application can be combined with each other.

[0475] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features, but these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A cylindrical battery cell, characterized in that: The diameter of the cylindrical battery cell is ≥40 mm, and the cylindrical battery cell comprises: shell; an electrode assembly at least partially contained within the housing; The electrode assembly comprises a positive electrode sheet, a negative electrode sheet and a separator, wherein the positive electrode sheet, the negative electrode sheet and the separator are wound, the separator separates the positive electrode sheet from the negative electrode sheet, and the negative electrode active material of the negative electrode sheet comprises at least one of a silicon-based material and a carbon-based material; At least one of the positive electrode sheet, the negative electrode sheet and the separator includes a base and a plurality of support portions, wherein the base has two first surfaces arranged opposite to each other along its thickness direction, and the plurality of support portions protrude from at least one of the first surfaces to form a gap between the positive electrode sheet and the negative electrode sheet.

2. The cylindrical battery cell according to claim 1, characterized in that: The support portion is configured to be compressible.

3. The cylindrical battery cell according to claim 1, characterized in that: The plurality of support portions include a first support portion and a second support portion, wherein a height of the first support portion protruding from the first surface is greater than a height of the second support portion protruding from the first surface.

4. The cylindrical battery cell according to claim 1, characterized in that: At least one of the positive electrode sheet, the negative electrode sheet, and the separator includes a plurality of organic particles, and the support portion includes the organic particles.

5. The cylindrical battery cell according to claim 4, characterized in that: The plurality of organic particles include first organic particles and second organic particles, and a number average particle size of the first organic particles is greater than a number average particle size of the second organic particles.

6. The cylindrical battery cell according to claim 4, characterized in that: The plurality of support portions include a first support portion and a second support portion, wherein a height of the first support portion protruding from the first surface is greater than a height of the second support portion protruding from the first surface; The plurality of organic particles include first organic particles and second organic particles; the first supporting portion includes the first organic particles, and the second supporting portion includes the second organic particles.

7. The cylindrical battery cell according to claim 1, characterized in that: The shell includes a side wall arranged around the electrode assembly, the material of the side wall includes steel, and the thickness of the side wall is 0.3 mm to 1.5 mm.

8. The cylindrical battery cell according to claim 1, characterized in that: The negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer disposed on at least one side of the negative electrode current collector and containing the negative electrode active material, wherein the negative electrode active material comprises a silicon-based material; The mass content of silicon element of the silicon-based material in the negative electrode film layer is 2% to 19%.

9. The cylindrical battery cell according to claim 1, characterized in that: The capacity surface density of the negative electrode sheet is greater than or equal to 3.2 mAh / cm 2 .

10. The cylindrical battery cell according to claim 9, characterized in that: The capacity surface density of the negative electrode sheet is 3.3 mAh / cm 2 Up to 11.5 mAh / cm 2 .

11. The cylindrical battery cell according to claim 10, characterized in that: The capacity surface density of the negative electrode sheet is 3.96 mAh / cm 2 Up to 7.56 mAh / cm 2 .

12. The cylindrical battery cell according to claim 1, characterized in that: The gap extends along the winding direction of the electrode assembly, and the gap has a winding start end and a winding end end.

13. The cylindrical battery cell according to claim 12, characterized in that: At least part of the gaps have a radial dimension of 5 μm-60 μm.

14. The cylindrical battery cell according to claim 12, characterized in that: The radial dimension of a portion of the gap close to the winding start end is greater than or equal to the radial dimension of a portion of the gap close to the winding end end.

15. The cylindrical battery cell according to claim 12, characterized in that: The radial dimension of at least part of the gap gradually decreases along the winding direction.

16. The cylindrical battery cell according to claim 12, characterized in that: The gap includes a middle region and two end regions arranged along the axial direction of the cylindrical battery cell, the middle region is located between the two end regions, and a radial dimension of the middle region is smaller than a radial dimension of the end regions.

17. The cylindrical battery cell according to claim 16, characterized in that: The radial dimension of the gap gradually decreases in a direction from the end region to the middle region.

18. The cylindrical battery cell according to claim 1, characterized in that: The spacer includes the base and a plurality of the support portions, and the support portions include organic particles disposed on the base.

19. The cylindrical battery cell according to claim 18, characterized in that: The base of the separator includes a base film and an inorganic particle layer disposed on the base film, and the organic particles at least partially protrude from the inorganic particle layer.

20. The cylindrical battery cell according to claim 1, characterized in that: A plurality of the supporting parts are provided on one side of the positive electrode sheet facing the separator, a plurality of the supporting parts are provided on one side of the separator facing the positive electrode sheet, and the plurality of supporting parts of the positive electrode sheet facing the separator and the plurality of supporting parts of the separator facing the positive electrode sheet are at least partially arranged opposite to each other; and / or, A plurality of the supporting parts are provided on one side of the negative electrode sheet facing the separator, a plurality of the supporting parts are provided on one side of the separator facing the negative electrode sheet, and the plurality of supporting parts of the negative electrode sheet facing the separator are at least partially arranged opposite to the supporting parts of the separator facing the plurality of negative electrode sheets; and / or, A plurality of the supporting parts are provided on the side of the negative electrode sheet facing the positive electrode sheet, and a plurality of the supporting parts are provided on the side of the positive electrode sheet facing the negative electrode sheet. The plurality of the supporting parts of the negative electrode sheet facing the positive electrode sheet are at least partially arranged opposite to the plurality of the supporting parts of the positive electrode sheet facing the negative electrode sheet.

21. The cylindrical battery cell according to claim 1, characterized in that: A plurality of the supporting parts are provided on both sides of the isolation member; The gap includes a first gap and a second gap, the first gap is formed between the positive electrode sheet and the separator, and the second gap is formed between the negative electrode sheet and the separator.

22. The cylindrical battery cell according to claim 1, characterized in that: One of the positive electrode sheet and the negative electrode sheet includes a first electrode tab, and the other includes a second electrode tab; The cylindrical battery cell comprises a first electrode lead-out portion and a second electrode lead-out portion, the first electrode lead-out portion is electrically connected to the first electrode tab, and the second electrode lead-out portion is electrically connected to the second electrode tab; In the axial direction of the cylindrical battery cell, the first electrode lead-out portion and the second electrode lead-out portion are located on the same side of the electrode assembly.

23. The cylindrical battery cell according to any one of claims 1 to 21, characterized in that: The housing includes a shell and an end cover, the shell includes an integrally formed side wall and an end wall, the side wall surrounds the electrode assembly, the end wall and the end cover are opposite to each other along the axial direction of the cylindrical battery cell, and the end cover is sealed and connected to the side wall.

24. The cylindrical battery cell according to claim 23, characterized in that: One of the positive electrode sheet and the negative electrode sheet includes a first electrode tab, and the other includes a second electrode tab; The cylindrical battery cell further includes an electrode terminal insulated and disposed on the end wall, one of the first electrode tab and the second electrode tab is electrically connected to the electrode terminal, and the other is electrically connected to the end wall.

25. The cylindrical battery cell according to claim 24, characterized in that: The cylindrical battery cell further includes a first current collecting member, the first current collecting member being located on a side of the first electrode tab facing the end wall and connected to the first electrode tab; The electrode terminal abuts against and is connected to a surface of the first current collecting member facing the end wall.

26. The cylindrical battery cell according to claim 25, characterized in that: The electrode terminal has a terminal recess on one side facing the first current collecting member, and / or the electrode terminal has a terminal recess on one side facing away from the first current collecting member; The bottom wall of the terminal recess is welded to the first current collecting member.

27. The cylindrical battery cell according to any one of claims 24 to 26, characterized in that: The first electrode tab and the second electrode tab are both located at one end of the electrode assembly facing the end wall.

28. The cylindrical battery cell according to any one of claims 24 to 26, characterized in that: The first electrode tab is located at one end of the electrode assembly facing the end wall, and the second electrode tab is located at one end of the electrode assembly facing the end cover; The cylindrical battery cell further includes a second current collecting member connected to the second electrode tab; the second current collecting member is connected to at least one of the end cover and the side wall.

29. The cylindrical battery cell according to claim 1, characterized in that: The height of the housing is 1.3 to 4 times the diameter of the housing.

30. The cylindrical battery cell according to claim 1, characterized in that: The height of the housing is 50 mm to 150 mm; and / or The diameter of the housing is 45 mm to 80 mm.

31. A battery, characterized in that: The invention comprises a plurality of cylindrical battery cells according to any one of claims 1 to 30.

32. An electrical device, characterized in that: A battery according to claim 31 for providing electrical energy.

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