Pole piece, cylindrical battery and electronic device

Abstract

The invention provides a pole piece, a cylindrical battery and an electronic device. The pole piece comprises a current collector; wherein one end of the current collector comprises an empty foil area, the empty foil area is provided with at least one first convex part, and the first convex part protrudes along the thickness direction of the pole piece and is used for being in contact with the side wall of a shell of the battery. According to the pole piece, the electric connection between the current collector and the side wall of the shell is realized through the contact between the first convex part and the side wall of the shell, so that the current collector plays a role of a tab, the tab does not need to be arranged, that is, one tab can be omitted in the embodiment, on one hand, the space occupied by the tab is saved, and the energy density of the battery can be improved; and on the other hand, two welding processes for connecting the tab and the shell are omitted, so that the production cost of the battery can be reduced.

Description

Technical Field

[0001] The present application relates to the field of electrochemical technology, and in particular to a pole piece, a cylindrical battery and an electronic device. Background Art

[0002] In the prior art, a cylindrical battery generally includes a positive electrode tab and a negative electrode tab. Both the positive electrode tab and the negative electrode tab have a certain thickness of about 60 μm. The two tabs are generally arranged in an upper and lower manner, and one of the tabs is bent at the bottom of the shell. For example, the negative electrode tab is generally bent at the bottom of the shell, occupying a layer of thickness space, resulting in a lower energy density of the battery. In addition, the tab bent at the bottom of the shell needs to undergo two welding processes to achieve electrical connection with the shell, which increases the production cost of the battery. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide a pole piece, a cylindrical battery and an electronic device to improve the energy density of the battery and reduce the manufacturing cost of the battery. The specific technical solution is as follows:

[0004] A first aspect of an embodiment of the present application provides a pole piece, comprising: a current collector, wherein one end of the current collector along the length direction comprises a hollow foil area, the hollow foil area is provided with at least one first protrusion, the first protrusion protrudes along the thickness direction of the pole piece, and is used to contact and electrically connect with the side wall of the battery shell.

[0005] In the present embodiment, the pole piece is in contact with the side wall of the shell through the first protrusion to achieve electrical connection between the current collector and the side wall of the shell, so that the current collector plays the role of a pole ear, and there is no need to set a pole ear. That is, one less pole ear can be set in the present embodiment. On the one hand, the space occupied by the pole ear is saved, which can improve the energy density of the battery; on the other hand, two welding processes when connecting the pole ear to the shell are saved, which can reduce the production cost of the battery.

[0006] In some embodiments, an electrode material is disposed on one side of the empty foil area, and the first protrusion is disposed on the other side opposite to the electrode material along the thickness direction of the electrode sheet.

[0007] In this embodiment, by arranging the electrode material on the side of the hollow foil area away from the first protrusion, more active materials can be arranged, and the energy density is improved to a certain extent.

[0008] In some embodiments, the first protrusion is a convex point structure, and a plurality of the first protrusions are arranged at intervals along the length direction and the width direction of the current collector.

[0009] In this way, a plurality of first protrusions can be arranged at intervals in the empty foil area to increase the contact area between the first protrusion and the side wall of the housing and increase the electrical connection stability. In addition, since the first protrusion has a small raised area, it will not cause the current collector to be distorted or deformed such as wrinkles.

[0010] In some embodiments, the outer contour of the convex dot-shaped structure is an arc, a cylinder, a cube, a cuboid, or a regular hexagon.

[0011] The outer contour of the convex point structure is arc-shaped, cylindrical, cubic or rectangular. When it contacts the side wall of the shell, the contact surface is a smooth arc surface or a flat plane without sharp corners. Therefore, it is not easy to puncture the shell or produce obvious stress concentration in the shell, which is beneficial to protecting the shell.

[0012] In some embodiments, the first protrusion is a long strip structure; the extension direction of the long strip structure is consistent with the length direction of the current collector, and the first protrusion is provided with one or multiple protrusions are arranged at intervals along the width direction of the current collector; or, the extension direction of the long strip structure is consistent with the width direction of the current collector, and the first protrusion is provided with one or multiple protrusions are arranged at intervals along the length direction of the current collector.

[0013] The first protrusion is a long strip structure, which is beneficial to reducing the number of first protrusions and ensuring sufficient contact area with the side wall of the shell.

[0014] In some embodiments, the outer contour of the elongated structure is semi-cylindrical or rectangular.

[0015] In this way, when the long strip structure contacts the side wall of the shell, its contact surface is either a smooth arc surface or a flat plane, which is not easy to produce obvious stress concentration in the local part of the shell, not easy to cause damage to the shell, and can achieve electrical connection between the current collector and the side wall of the shell.

[0016] In some embodiments, the first protrusion is formed by punching the current collector from a side where the electrode material is disposed, or the first protrusion is connected to a surface of the current collector that is away from the electrode material.

[0017] The first convex portion is formed by stamping, and no additional current collector material is needed. The method is simple and easy to operate.

[0018] The first protrusion is connected to the surface of the current collector facing away from the electrode material, for example, by spot welding. The first protrusion can be arranged more densely without causing the current collector to deform such as wrinkles and twists. Therefore, the height of the first protrusion is less affected by the ductility of the current collector.

[0019] In some embodiments, when a plurality of first protrusions are provided at intervals along the length direction and the width direction of the current collector, a first distance between adjacent first protrusions is greater than or equal to 1 mm and less than or equal to 5 mm.

[0020] A reduction in the first distance between adjacent first protrusions will increase the difficulty of the process, but can increase the contact area between the first protrusion and the side wall of the shell, and increase the stability and reliability of the electrical connection. An increase in the first distance between adjacent first protrusions will reduce the difficulty of the process, but will reduce the number of first protrusions, thereby reducing the contact area between the first protrusion and the side wall of the shell, and weakening the stability and reliability of the electrical connection. Therefore, within the allowable range of the process, the first distance between adjacent first protrusions can be set to be greater than or equal to 1 mm and less than or equal to 5 mm.

[0021] In some embodiments, the height of the first protrusion is greater than or equal to 35 μm and less than or equal to 100 μm. The height of the first protrusion is set to be greater than or equal to 35 μm, so that the pole piece is wound into a battery core, and when it is installed in the shell, the first protrusion can better achieve interference fit with the side wall of the shell, increasing the stability and reliability of the electrical connection. And the height of the first protrusion is greater than or equal to 35 μm, which is easy to achieve by stamping, will not cause damage to the current collector, and simplifies the manufacturing process of the first protrusion. When the first protrusion is greater than 100 μm, it may cause the first protrusion to be too high and difficult to install into the shell.

[0022] In some embodiments, along the thickness direction of the pole piece, the projection area of ​​the first protrusion is greater than or equal to 0.196 mm 2 Up to 0.785mm 2 In this way, the molding of the first convex portion can be simplified. When the area is less than 0.196mm 2 When the area is larger than 0.785mm, the electrical connection area of ​​each first protrusion may be small, affecting the flow conductivity. 2 When the current collector is stamped, the stamping area is too large, which makes the strength of the current collector lower and easily leads to damage of the current collector.

[0023] In some embodiments, the elastic modulus of the current collector is 110 GPa-130 GPa. Limiting the elastic modulus of the current collector to between 110 GPa-130 GPa can achieve a better interference fit between the first protrusion and the side wall of the housing. Too low an elastic modulus will result in poor elasticity and difficulty in achieving interference fit, and too high an elastic modulus will make the material too brittle and easy to break.

[0024] In some embodiments, the electrode piece is a negative electrode piece.

[0025] When the electrode is a negative electrode, the electrode is in contact and electrically connected with the side wall of the shell, then the shell can act as a negative electrode. When the shell acts as a negative electrode, it is not easy to cause corrosion to the shell itself, and the optional materials are also more extensive. For example, ordinary steel shell is not easily corroded as a negative electrode.

[0026] A second aspect of the present application provides a cylindrical battery, which includes: a shell having an opening at one end, including a bottom wall opposite to the opening and a side wall connected to the bottom wall; a shell cover covering the opening; a bare cell placed in the shell, the bare cell being formed by winding a first pole piece, a diaphragm, and a second pole piece, the first pole piece including a first current collector and a first electrode material provided on the first current collector, the outermost circle of the first current collector along the winding direction including an empty foil area; wherein the empty foil area is provided with at least one first convex portion, the first convex portion protrudes toward the direction of the side wall, the first convex portion is in contact with and electrically connected to the side wall; and / or, the shell is provided with at least one second convex portion, the second convex portion protrudes toward the direction of the empty foil area, the second convex portion is in contact with and electrically connected to the first current collector.

[0027] The first pole piece is in contact with the side wall of the shell through the first protrusion to achieve an interference fit between the bare battery cell and the side wall of the shell, or the shell is interfered with by the second protrusion and the first pole piece, thereby achieving electrical connection between the first current collector and the shell, so that the first current collector plays the role of a pole ear, and no pole ear is required, that is, one less pole ear can be set in this embodiment, on the one hand, the space occupied by the pole ear is saved, which can improve the energy density of the battery; on the other hand, the two welding processes when the pole ear is connected to the shell are saved, and these two welding processes account for about 9% of the total cost of the battery cell. Therefore, by setting the first protrusion on the first pole piece, the production cost of the battery can be greatly reduced. In addition, if there is no pole ear on the first pole piece, stress concentration occurs at the bonding point of the pole ear, which reduces the risk of easy breakage of the pole piece and improves the safety of the battery.

[0028] In some embodiments, a first electrode material is disposed on one side of the hollow foil region facing the bare battery cell, and the first protrusion is disposed on the other side opposite to the first electrode material along the thickness direction of the hollow foil region.

[0029] In this embodiment, by arranging the first electrode material on the side of the hollow foil area away from the first protrusion, more active materials can be arranged, and the energy density is improved to a certain extent.

[0030] In some embodiments, along the axial direction perpendicular to the cylindrical battery, the second distance from the bare cell to the side wall of the battery is greater than or equal to 25 μm and less than or equal to 75 μm. In this embodiment, by limiting the gap between the side wall of the battery and the bare cell, the first convex portion can better achieve interference fit and achieve electrical connection stability. If the distance from the bare cell to the battery shell is too small, it will make it difficult to install the bare cell into the shell, and if the distance is too large, the electrical connection stability will be poor.

[0031] In some embodiments, the area of ​​the empty foil region is 1 / 3 to 1 of the area of ​​the outermost circle of the first current collector.

[0032] In this embodiment, when the area of ​​the empty foil area is less than 1 / 3 of the area surrounding the outermost circle of the first current collector, the setting area of ​​the empty foil area is reduced. When the total thickness of the battery is constant, it is equivalent to increasing the area used to coat the first electrode material, which is beneficial to improving the energy density of the battery.

[0033] In some embodiments, the area of ​​the empty foil region is equal to the area of ​​the outermost circle of the current collector, and the line connecting the at least two first protrusions passes through the winding center.

[0034] In this embodiment, the connection line of at least two first protrusions passes through the winding center, so that along the connection direction, the distance between the two sides of the bare battery cell and the side wall of the shell is equal, and the height of the first protrusion is equal to the distance between the two. Compared with the battery cell placed to one side, the distance on the other side is twice the distance on one side when placed in the center. Therefore, the connection line of at least two first protrusions passes through the winding center, which can reduce the height of the first protrusion and reduce the difficulty of manufacturing the first protrusion.

[0035] In some embodiments, the second pole sheet includes a positive electrode tab, which extends from an end of the second current collector away from the bottom wall. Along the width direction of the first current collector, a third distance between the first protrusion away from the bottom wall end and the edge of the first current collector away from the bottom wall end is greater than or equal to 0.15 mm.

[0036] In this embodiment, the first pole piece is a negative pole piece, and the second pole piece is a positive pole piece. The positive pole tab is provided at the top of the battery, and the third distance between the first protrusion and the top of the first current collector is greater than or equal to 0.15 mm, so that the first protrusion can be away from the positive pole tab to avoid interference with the positive pole tab and cause risks such as short circuit.

[0037] In some embodiments, the second protrusion is a convex dot structure or a long strip structure.

[0038] In this way, a plurality of second protrusions can be arranged at intervals on the side wall of the housing to increase the contact area between the second protrusions and the empty foil area and increase the stability of the electrical connection. In addition, since the raised area of ​​the second protrusions is small, the housing will not be distorted or deformed such as wrinkles.

[0039] In some embodiments, the second protrusion is formed by stamping or rolling the shell, or the second protrusion is connected to a side of the shell facing the bare battery cell.

[0040] The second convex portion is formed by stamping or rolling, without the need to add additional shell material, and the method is simple and easy to operate. By rolling, the bare cell can be rolled after it is put into the shell, which increases the contact area between the shell and the empty foil area by increasing the rolling area, which is beneficial to improving the stability and reliability of the electrical connection. The electrical connection between the shell and the empty foil area is achieved by rolling, which does not affect the entry of the bare cell into the shell.

[0041] The second protrusion is connected to the surface of the shell facing the bare cell, for example, by spot welding. The second protrusion can be arranged more densely without causing the shell to be wrinkled, twisted or deformed. Therefore, the height of the second protrusion is less affected by the ductility of the shell.

[0042] In some embodiments, along the height direction of the battery, the shell includes a first section and a second section, the first section is a section close to the opening, and the opening area of ​​the first section gradually increases along the direction close to the opening.

[0043] In this embodiment, the shell is in the form of an outward-expanding trumpet mouth, and the first section of the outward-expanding type can play a guiding role, making it easier for the bare battery cell to enter the shell.

[0044] In some embodiments, the battery includes a support member, which is located at the center of the bare cell and is used to support the bare cell.

[0045] In this embodiment, the support member is located in the inner hole of the bare cell and serves as an inner ring support to prevent the inner ring of the bare cell from collapsing. It can also provide support for the empty foil area of ​​the outermost ring and the side wall of the shell to achieve effective contact. The use of the support member can be selectively used according to the expansion rate of the anode. For example, when the anode expansion rate is large, the support member can be selected. The material of the support member can be an insulating polymer material or a foam material, including but not limited to PE / PP round rods or balls, polyester foam glue, etc.

[0046] The third aspect of the present application provides an electronic device, which includes the above cylindrical battery. The electronic device can be a mobile phone, a computer, a telephone watch, etc. The electronic device includes a cylindrical battery, and the cylindrical battery can be provided with one less tab. On the one hand, the space occupied by the tab is saved, which can improve the energy density of the battery; on the other hand, the two welding processes when the tab is connected to the shell are saved, and these two welding processes account for about 9% of the total cost of the battery cell, so the production cost of the electronic device can be greatly reduced.

[0047] Of course, implementing any product or method of the present application does not necessarily require achieving all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other embodiments can also be obtained based on these drawings.

[0049] Figure 1 A schematic diagram of the structure of a pole piece provided in an embodiment of the present application;

[0050] Figure 2 for Figure 1 Schematic diagram of the structure on the other side of the middle electrode;

[0051] Figure 3 A schematic diagram of the structure of a pole piece provided in an embodiment of the present application in another embodiment;

[0052] Figure 4 for Figure 3 Schematic diagram of the structure on the other side of the middle electrode;

[0053] Figure 5 A schematic diagram of an exploded structure of a battery provided in an embodiment of the present application;

[0054] Figure 6 for Figure 5 A cross-sectional view of a battery;

[0055] Figure 7 A schematic diagram of the structure of a bare battery cell after being put into a shell and before being formed provided in an embodiment of the present application;

[0056] Figure 8 A schematic diagram of the local structure of a bare battery cell after being put into a shell and formed according to an embodiment of the present application;

[0057] Fig. 9 for Figure 5 Schematic diagram of the structure of the bare battery cell;

[0058] Fig.10 A schematic diagram of the structure of the housing provided in an embodiment of the present application in another embodiment;

[0059] Fig.11 A schematic diagram of an exploded structure of a battery provided in an embodiment of the present application in another embodiment, wherein the shell opening is an outward-expanding horn opening;

[0060] Fig.12 for Fig.11 Schematic diagram of the process of putting the bare cell of the medium battery into the shell;

[0061] Fig.13 for Fig.11 Schematic diagram of the structure of the bare cell of the medium battery after it is completely put into the shell but before it is formed;

[0062] Fig.14 for Fig.11 Schematic diagram of the partial structure of the medium battery after the bare cell is completely put into the shell and formed;

[0063] Fig.15 A schematic diagram of the structure of adding support parts to a bare battery cell;

[0064] Fig.16 This is the battery cycle performance curve after adding support members.

[0065] Shell 1; opening 11; bottom wall 12; side wall 13; first section 131; second section 132; second convex portion 133; shell cover 2; bare cell 3; pole piece 31; first pole piece 31a; second pole piece 31b; positive electrode tab 31b1; current collector 311; electrode material 312; empty foil area 3111; first convex portion 3111a; diaphragm 32; support member 33; first distance L1; second distance L2; third distance L3. DETAILED DESCRIPTION

[0066] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field based on the present application belong to the scope of protection of the present application.

[0067] In order to solve the problem that in a cylindrical battery, when the tab is electrically connected to the shell 1, it occupies a layer of thickness space, resulting in low energy density of the cylindrical battery, and the tab and the shell 1 need to go through two welding processes when welding, which is costly. In a first aspect of the embodiment of the present application, a pole piece 31 is provided, such as Figure 1 , Figure 2 As shown, the pole piece 31 includes: a current collector 311. Among them, one end of the current collector 311 along the length direction includes an empty foil area 3111, and the empty foil area 3111 is provided with at least one first convex portion 3111a, and the first convex portion 3111a protrudes along the thickness direction of the pole piece 31, and is used to contact and electrically connect with the side wall 13 of the battery housing 1. Among them, the side away from the electrode material 312 refers to the side where the first convex portion 3111a and the electrode material 312 do not overlap in the thickness direction of the pole piece 31.

[0068] The empty foil area 3111 referred to in the present application is an area where no electrode material is provided on at least one side.

[0069] In this embodiment, the pole piece 31 contacts the side wall 13 of the shell 1 through the first protrusion 3111a to achieve electrical connection between the current collector 311 and the side wall 13 of the shell 1, so that the current collector 311 plays the role of a pole ear, and there is no need to set a pole ear. That is, one less pole ear can be set in this embodiment. On the one hand, the space occupied by the pole ear is saved, which can improve the energy density of the battery; on the other hand, two welding processes when connecting the pole ear to the shell 1 are saved, and these two welding processes account for about 9% of the total cost of the battery cell. Therefore, by setting the first protrusion 3111a on the pole piece 31, the production cost of the battery can be greatly reduced.

[0070] In addition, since no pole lug is provided on the pole piece 31 , stress concentration occurs at the bonding point of the pole lug, and the risk of the pole piece 31 being easily broken is also reduced.

[0071] In some embodiments of the present application, Figure 1 , Figure 2 As shown, the electrode material 312 is disposed on one side of the empty foil area 3111 , and the first protrusion 3111 a is disposed on the other side opposite to the electrode material 312 along the thickness direction of the electrode sheet.

[0072] In this embodiment, by providing the electrode material 312 on the side of the empty foil area 3111 away from the first protrusion 3111a, more active materials can be provided, and the energy density is improved to a certain extent.

[0073] In some embodiments of the present application, Figure 1 , Figure 2 As shown, the first convex portion 3111 a is a convex point structure, and a plurality of the first convex portions 3111 a are arranged at intervals along the length direction and the width direction of the current collector 311 .

[0074] In this embodiment, the convex point structure refers to the first convex portion 3111a being in a bulging shape. In this way, a plurality of first convex portions 3111a can be arranged at intervals in the empty foil area 3111 to increase the contact area between the first convex portion 3111a and the side wall 13 of the housing 1 and increase the electrical connection stability. And because the convex area of ​​the first convex portion 3111a is small, it will not cause the current collector 311 to be distorted or deformed such as wrinkles.

[0075] In some embodiments of the present application, the outer contour of the convex point structure is an arc, a cylinder, a cube, a cuboid or a regular hexagon, such as Figure 1 , Figure 2 The outer contour of the convex point structure is a hemispherical shape as an example for illustration, wherein the hemispherical shape is a type of arc shape.

[0076] In this embodiment, the outer contour of the convex point structure is arc-shaped, cylindrical, cubic or rectangular. When it contacts the side wall 13 of the shell 1, the contact surface is a smooth arc surface or a flat plane. Therefore, when the first protrusion 3111a contacts the side wall 13 of the shell 1, it is not easy to puncture the shell 1 or produce obvious stress concentration in the local part of the shell 1, which is beneficial to protecting the shell 1.

[0077] In some embodiments of the present application, Figure 3 , Figure 4 As shown, the first protrusion 3111a is a long strip structure, and Figure 3 , Figure 4The extending direction of the medium-long strip is consistent with the length direction of the current collector 311. The extending direction of the long strip structure is consistent with the length direction of the current collector 311, and the first convex portion 3111a is provided with one or multiple convex portions are provided at intervals along the width direction of the current collector 311. Alternatively, the extending direction of the long strip structure is consistent with the width direction of the current collector 311, and the first convex portion 3111a is provided with one or multiple convex portions are provided at intervals along the length direction of the current collector 311.

[0078] In this embodiment, the first convex portion 3111a is a long strip structure, which can be understood as a length of the first convex portion 3111a, that is, a dimension in the extension direction, which is of the same order of magnitude as the dimension in the length direction or width direction of the empty foil area 3111, and a width of the first convex portion 3111a is at least one order of magnitude smaller than the dimension in the length direction or width direction of the empty foil area 3111. The first convex portion 3111a is a long strip structure, which is conducive to reducing the number of first convex portions 3111a and ensuring sufficient contact area with the side wall 13 of the housing 1.

[0079] The first convex portion 3111a is a long strip structure, and its length can be arranged along the length direction of the current collector 311 . The number of the first convex portion 3111a can be one or more, such as two or more. When the number of the first convex portion 3111a is more than one, the first convex portion 3111a is arranged at intervals along the width direction of the current collector 311 .

[0080] The first convex portion 3111a is a long strip structure, and its length can also be arranged along the width direction of the current collector 311 . The number of the first convex portion 3111a can be one or more, such as two or more. When the number of the first convex portion 3111a is more than one, they are arranged at intervals along the length direction of the current collector 311 .

[0081] In some embodiments of the present application, the outer contour of the long strip structure is a semi-cylindrical or rectangular parallelepiped shape. In this way, when the long strip structure contacts the side wall 13 of the shell 1, its contact surface is either a smooth arc surface or a flat plane, which is not easy to generate obvious stress concentration in the shell 1, is not easy to cause damage to the shell 1, and can achieve electrical connection between the current collector 311 and the side wall 13 of the shell 1.

[0082] In some embodiments of the present application, the first protrusion 3111 a is formed by punching the current collector 311 from a side where the electrode material 312 is provided, or the first protrusion 3111 a is connected to a surface of the current collector 311 facing away from the electrode material 312 .

[0083] The first protrusion 3111 a is formed by stamping, and no additional material for the current collector 311 is required. The method is simple and easy to operate.

[0084] The first convex portion 3111a is connected to the surface of the current collector 311 away from the electrode material 312, for example, by spot welding. The first convex portions 3111a can be arranged more densely without causing the current collector 311 to be deformed such as wrinkled or twisted. Therefore, the height of the first convex portions 3111a is less affected by the ductility of the current collector 311.

[0085] Optionally, the material of the first protrusion 3111 a may be consistent with the material of the current collector 311 , so as to reduce the difficulty of welding and improve the firmness of welding.

[0086] In some embodiments of the present application, when multiple first protrusions 3111a are spaced apart along the length and width directions of the current collector 311, the first distance L1 between adjacent first protrusions 3111a is greater than or equal to 1mm and less than or equal to 5mm, for example, it can be 1mm, 1.5mm, 2mm, 3mm, 4mm, 5mm, etc.

[0087] In this embodiment, the first distance L1 between adjacent first protrusions 3111a is reduced, which will increase the difficulty of the process, but can increase the contact area between the first protrusion 3111a and the side wall 13 of the housing 1, thereby increasing the stability and reliability of the electrical connection. The first distance L1 between adjacent first protrusions 3111a is increased, which will reduce the difficulty of the process, but will reduce the number of first protrusions 3111a, thereby reducing the contact area between the first protrusion 3111a and the side wall 13 of the housing 1, and weakening the stability and reliability of the electrical connection. Therefore, within the allowable range of the process, the first distance L1 between adjacent first protrusions 3111a can be set to be greater than or equal to 1mm and less than or equal to 5mm.

[0088] In some embodiments of the present application, Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, the height of the first protrusion 3111a is greater than or equal to 35 μm and less than or equal to 100 μm, for example, it can be 35 μm, 40 μm, 45 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, etc.

[0089] In this embodiment, the height of the first convex portion 3111a is set to be greater than or equal to 35 μm, so that when the pole piece 31 is wound into a battery core and installed in the housing 1, the first convex portion 3111a can better achieve interference fit with the side wall 13 of the housing 1, thereby increasing the stability and reliability of the electrical connection. The height of the first convex portion 3111a is greater than or equal to 35 μm, which is easy to achieve by stamping, does not cause damage to the current collector 311, and simplifies the manufacturing process of the first convex portion 3111a. When the first convex portion 3111a is greater than 100 μm, the first convex portion 3111a may be too high and difficult to install into the housing.

[0090] In some embodiments of the present application, the elastic modulus of the current collector 311 is 110Gpa-130Gpa. Limiting the elastic modulus of the current collector 311 to between 110GPa-130Gpa can make the first protrusion 3111a and the side wall 13 of the shell 1 have a better interference fit. Too low elastic modulus will lead to poor elasticity and difficulty in achieving interference fit. Too high elastic modulus will make the material too brittle and easy to break. In some embodiments of the present application, the pole piece 31 is a negative pole piece 31. When the pole piece 31 is a negative pole piece 31, the pole piece 31 is in contact and electrically connected with the side wall 13 of the shell 1, then the shell 1 can act as a negative pole. When the shell 1 is used as a negative pole, it is not easy to cause corrosion to the shell 1 itself, and the optional materials are more extensive. For example, ordinary steel shells are not easily corroded as negative poles.

[0091] The second aspect of the present application provides a cylindrical battery, such as Figure 5 , Figure 6 , Figure 7 As shown, the cylindrical battery includes: a shell 1, a shell cover 2 and a bare cell 3. The shell 1 has an opening 11 at one end, and the shell 1 includes a bottom wall 12 opposite to the opening 11 and a side wall 13 connected to the bottom wall 12. The shell cover 2 covers the opening 11. The bare cell 3 is placed in the shell 1 through the opening 11. The bare cell 3 is wound by a first pole piece 31a, a diaphragm 32 and a second pole piece 31b. The first pole piece 31a includes a first current collector and a first electrode material provided on the first current collector. The outermost circle of the first current collector along the winding direction includes an empty foil area 3111. Among them, the empty foil area 3111 is provided with at least one first protrusion 3111a, the first protrusion 3111a protrudes toward the side wall 13, and the first protrusion 3111a is in contact with and electrically connected to the side wall 13; and / or, the shell 1 is provided with at least one second protrusion 133, the second protrusion 133 protrudes toward the empty foil area 3111, and the second protrusion 133 is in contact with and electrically connected to the first current collector.

[0092] In this embodiment, the first pole piece 31a is in contact with the side wall 13 of the shell 1 through the first protrusion 3111a to achieve an interference fit between the bare battery cell 3 and the side wall 13 of the shell 1, or the shell 1 is in interference fit with the bare battery cell 3 through the second protrusion 133, thereby achieving electrical connection between the first current collector and the shell 1, so that the first current collector plays the role of a pole ear, and no pole ear is required, that is, one less pole ear can be set in this embodiment, on the one hand, the space occupied by the pole ear is saved, and the energy density of the battery can be improved; on the other hand, the two welding processes when the pole ear is connected to the shell 1 are saved, and these two welding processes account for about 9% of the total cost of the battery cell. Therefore, by setting the first protrusion 3111a on the first pole piece 31a, the production cost of the battery can be greatly reduced. In addition, since no pole ear is set on the first pole piece 31a, stress concentration occurs at the bonding point of the pole ear, which reduces the risk of easy breakage of the pole piece 31 and improves the safety of the battery.

[0093] In addition, by making the first protrusion 3111a and the side wall 13 of the shell 1 to achieve electrical connection through interference fit, compared with the electrical connection through the pole ear and the bottom wall 12 of the shell 1 by welding, a top rod provided at the winding center of the bare battery cell 3 for pressing the pole ear to electrically connect the pole ear to the bottom wall 12 of the shell 1 can be omitted, so that the inner aperture of the bare battery cell 3 can be made smaller, and the thickness space occupied by a layer of pole ears can be omitted, so the energy density of the overall battery can be increased by at least about 3%. At the same time, since the top rod located in the center of the bare battery cell 3 is omitted, the compatibility with the silicon system with larger expansion is better. Because the first pole piece 31a of the silicon system expands more, it will squeeze the inner hole of the bare battery cell 3, causing the inner circle to collapse, posing a safety risk.

[0094] It can be understood that the first pole piece 31a can be a positive pole piece 31 or a negative pole piece 31. When the first pole piece 31a is a positive pole piece 31, the battery housing 1 is positively charged, and when the first pole piece 31a is a negative pole piece 31, the battery housing 1 is negatively charged. In addition, the first pole piece 31a can be a pole piece 31 closer to the winding center than the second pole piece 31b, or a pole piece 31 farther from the winding center than the second pole piece 31b, that is, the first pole piece 31a is not limited by its position during winding, as long as the outermost circle of the first pole piece 31a can be interference-fitted with the side wall 13 of the housing 1 by setting the first protrusion 3111a.

[0095] like Figure 7As shown, the bare cell 3 and the shell 1 form a partial or overall interference fit between the empty foil area 3111 of the outermost circle of the first current collector and the side wall 13 of the shell 1 to provide an initial electrical connection, so that the cell can complete the first charge, that is, complete the formation process. After formation, the negative electrode sheet 31 expands and continues to expand during the subsequent cycle charge and discharge process, pressing the empty foil area 3111 of the outer circle of the bare cell 3 against the side wall 13 of the shell 1, as shown in FIG. Figure 8 The end position of the empty foil area 3111 is bounded by end glue, and the end glue can be conductive adhesive film, ordinary single-sided adhesive tape and double-sided adhesive tape, and the ordinary single-sided adhesive tape and ordinary double-sided adhesive tape can be swelling adhesive tape or non-swelling ordinary adhesive tape.

[0096] In some embodiments of the present application, a first electrode material is disposed on one side of the empty foil area 3111 facing the bare battery cell 3 , and the first protrusion 3111 a is disposed on the other side opposite to the first electrode material along the thickness direction of the empty foil area 3111 .

[0097] In this embodiment, by arranging the first electrode material on the side of the empty foil area 3111 away from the first protrusion 3111a, more active materials can be arranged, and the energy density is improved to a certain extent.

[0098] In some embodiments of the present application, Figure 6 As shown, along the axial direction perpendicular to the cylindrical battery, the second distance L2 from the bare cell 3 to the side wall 13 of the battery 1 is greater than or equal to 25 μm and less than or equal to 75 μm. In this embodiment, by limiting the gap between the side wall 13 of the battery 1 and the bare cell 3, the first protrusion 3111a can better achieve interference fit and achieve electrical connection stability. If the second distance L2 from the bare cell 3 to the side wall 13 of the battery 1 is too small, it will make it difficult to install the bare cell 3 into the shell, and if the distance is too large, the electrical connection stability will be poor.

[0099] In some embodiments of the present application, Fig. 9 As shown, the area of ​​the empty foil area 3111 is 1 / 3 to 1 of the area of ​​the outermost circle of the first current collector. For example, the area of ​​the empty foil area 3111 can be 1 / 3, 1 / 2, or equal to the area of ​​the outermost circle of the first current collector.

[0100] In this embodiment, when the area of ​​the empty foil area 3111 is smaller than the area surrounding the outermost circle of the first current collector, the setting area of ​​the empty foil area 3111 is reduced. When the total thickness of the battery is constant, it is equivalent to increasing the area used to coat the first electrode material, which is beneficial to improving the energy density of the battery.

[0101] When the area of ​​the empty foil region 3111 is larger than 1 / 3 of the area of ​​the outermost circle of the first current collector, under the condition that the total thickness of the battery is constant, two first protrusions 3111a can respectively cooperate with the side wall 13 of the shell 1 along the diameter direction of the bare battery cell 3, thereby reducing the protruding height of the first protrusion 3111a and reducing the difficulty of manufacturing the first protrusion 3111a.

[0102] When the area of ​​the empty foil area 3111 is equal to the area of ​​the outermost circle of the first current collector, under the condition of a certain total thickness of the battery, the two first protrusions 3111a can be respectively matched with the side wall 13 of the shell 1 along the diameter direction of the bare battery cell 3, so that the protrusion height of the first protrusion 3111a can be reduced, and the difficulty of making the first protrusion 3111a can be reduced. In addition, the contact area between the first protrusion 3111a and the side wall 13 of the shell 1 can be increased, which is conducive to improving the electrical connection stability and reliability between the first protrusion 3111a and the shell 1.

[0103] In some embodiments of the present application, the area of ​​the empty foil region 3111 is equal to the area of ​​the outermost circle of the current collector 311, and the line connecting at least two first protrusions 3111a passes through the winding center.

[0104] In this embodiment, the connection line of at least two first protrusions 3111a passes through the winding center, so that along the connection direction, the distance between the two sides of the bare battery cell 3 and the side wall 13 of the shell 1 is equal, and the height of the first protrusion 3111a is equal to the distance between the two. Compared with the battery cell placed to one side, the distance on the other side is twice the distance on one side when placed in the center. Therefore, the connection line of at least two first protrusions 3111a passes through the winding center, which can reduce the height of the first protrusion 3111a and reduce the difficulty of manufacturing the first protrusion 3111a.

[0105] In some embodiments of the present application, Figure 6 , Fig. 9 As shown, the second pole piece 31b includes a positive electrode tab 31b1, which extends from one end of the second current collector 311 away from the bottom wall 12. Along the width direction of the first current collector, a third distance L3 between the first protrusion 3111a away from the end of the bottom wall 12 and the edge of the first current collector away from the end of the bottom wall 12 is greater than or equal to 0.15mm, for example, it can be 0.15mm, 0.2mm, 0.25mm, etc.

[0106] In this embodiment, the first electrode sheet 31a is a negative electrode sheet 31, and the second electrode sheet 31b is a positive electrode sheet 31. Fig. 9As shown, the positive electrode tab 31b1 is arranged at the top of the battery, and the third distance L3 between the first protrusion 3111a and the top of the first current collector is greater than or equal to 0.15mm, so that the first protrusion 3111a can be away from the positive electrode tab 31b1 to avoid interference with the positive electrode tab 31b1 and cause risks such as short circuit.

[0107] In some embodiments of the present application, Fig.10 As shown, the second convex portion 133 is a convex point structure or a long strip structure.

[0108] In this embodiment, the convex point structure of the second convex portion 133 means that the second convex portion 133 is in a bulging shape. The convex point structure means that the dimensions of the second convex portion 133 in the length direction and the width direction are in the same order of magnitude, and the dimensions in the length direction and the width direction are at least one order of magnitude smaller than the length and width of the side wall 13 of the shell 1. For example, when the size of the side wall 13 is 10mm*8mm, the bulging area of ​​the first convex portion 3111a does not exceed 1mm 2 In this way, a plurality of second protrusions 133 can be arranged at intervals on the side wall 13 of the housing 1 to increase the contact area between the second protrusion 133 and the empty foil area 3111, thereby increasing the stability of the electrical connection. And because the raised area of ​​the second protrusion 133 is small, it will not cause the housing 1 to be distorted or deformed, such as wrinkles.

[0109] The second convex portion 133 is a long strip structure, and its length can be arranged along the length direction of the side wall 13. The number of the second convex portion 133 can be one or more, such as two or more. When the number of the second convex portion 133 is multiple, the second convex portion 133 is a long strip structure, and its length can be arranged along the width ...

[0110] In some embodiments of the present application, Fig.10 As shown, the second protrusion 133 is formed by stamping or rolling the shell 1 , or the second protrusion 133 is connected to a side of the shell 1 facing the bare battery cell 3 .

[0111] The second convex portion 133 is formed by stamping or rolling, without adding additional material to the shell 1, and the method is simple and easy to operate. By rolling, the bare battery cell 3 can be rolled after it is put into the shell, which is convenient for increasing the contact area between the shell 1 and the empty foil area 3111 by increasing the rolling area, which is conducive to improving the stability and reliability of the electrical connection. The electrical connection between the shell 1 and the empty foil area 3111 is achieved by rolling, which does not affect the entry of the bare battery cell 3 into the shell.

[0112] The second protrusion 133 is connected to the surface of the shell 1 facing the bare cell 3, for example, by spot welding. The second protrusions 133 can be arranged more densely without causing the shell 1 to be wrinkled, twisted or deformed. Therefore, the height of the second protrusion 133 is less affected by the ductility of the shell 1.

[0113] In some embodiments of the present application, Fig.11 , Fig.12 , Fig.13 As shown, along the height direction of the battery, the housing 1 includes a first section and a second section, the first section is a section close to the opening 11, and the area of ​​the opening 11 gradually increases along the direction of the first section close to the opening 11.

[0114] In this embodiment, the shell 1 is in the form of an outward-expanding trumpet mouth, and the outward-expanding first section can play a guiding role, making it easier for the bare battery cell 3 to enter the shell. Figure 12 to Figure 13 The bare cell is shown from the beginning to the end of the shell. Fig.13 It can be seen that after the bare cell is put into the shell, the first protrusion 3111a is partially interference fit with the side wall 13 of the shell 1 to provide an initial electrical connection. After one charge and completion of battery formation, the negative electrode sheet 31 expands and continues to expand during the subsequent cycle charge and discharge process, pressing the empty foil area 3111 of the outer ring of the bare cell 3 against the side wall 13 of the shell 1, as shown in FIG. Fig.14 As shown, a more stable electrical connection can be provided.

[0115] In some embodiments of the present application, Fig.15 As shown, the battery includes a support member 33 , which is located at the center of the bare battery cell 3 and is used to support the bare battery cell 3 .

[0116] In this embodiment, the support member 33 is located in the inner hole of the bare cell 3. As an inner ring support, it can prevent the inner ring of the bare cell 3 from collapsing, and can also provide support for the outermost empty foil area 3111 and the side wall 13 of the shell 1 to achieve effective contact. The use of the support member 33 can be selectively used according to the expansion rate of the anode. For example, when the anode expansion rate is large, the support member can be selected. The material of the support member 33 can be an insulating polymer material or a foaming material, including but not limited to PE / PP round rods or balls, polyester foaming glue, etc.

[0117] For the embodiment in which the support member 33 is provided, the capacity attenuation curve of the battery is tested by cyclic charge and discharge, and it is found that the capacity attenuation curve decreases slightly with the increase of the number of cycles, such as Fig.16 As shown, it conforms to the attenuation law of battery capacity and there is no abnormality, which proves that setting the support member 33 is feasible to a certain extent.

[0118] A second aspect of the present application provides an electronic device, which includes the cylindrical battery described above.

[0119] In this embodiment, the electronic device can be a mobile phone, a computer, a telephone watch, etc. The electronic device includes a cylindrical battery, and the cylindrical battery can be provided with one less pole ear. On the one hand, the space occupied by the pole ear is saved, which can improve the energy density of the battery; on the other hand, the two welding processes when the pole ear is connected to the shell 1 are saved, and these two welding processes account for about 9% of the total cost of the battery cell, so the production cost of the electronic device can be greatly reduced. In addition, the pole ear is not provided on the first pole piece 31a, and stress concentration occurs at the bonding point of the pole ear, which reduces the risk of the pole piece 31 being easily broken, and can also improve the safety of the battery, thereby improving the safety of the use of the electronic device.

[0120] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0121] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0122] The above description is only a preferred embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application are included in the protection scope of the present application.

Claims

1. A pole piece, characterized in that: include: current collector; Among them, one end of the current collector along the length direction includes an empty foil area, and the empty foil area is provided with at least one first convex portion, which protrudes along the thickness direction of the pole piece and is used to contact and electrically connect with the side wall of the battery shell.

2. The pole piece according to claim 1, characterized in that: The electrode material is disposed on one side of the empty foil area, and the first protrusion is disposed on the other side opposite to the electrode material along the thickness direction of the electrode sheet.

3. The pole piece according to claim 1, characterized in that: The first convex portion is a convex point structure, and a plurality of the first convex portions are arranged at intervals along the length direction and the width direction of the current collector.

4. The pole piece according to claim 3, characterized in that: The outer contour of the convex point structure is arc-shaped, cylindrical, cubic, cuboid or regular hexagonal.

5. The pole piece according to claim 1, characterized in that: The first convex portion is a long strip structure; The extending direction of the long strip structure is consistent with the length direction of the current collector, and the first convex portion is provided with one or a plurality of convex portions are arranged at intervals along the width direction of the current collector; or The extending direction of the long strip structure is consistent with the width direction of the current collector, and one first protrusion is provided or a plurality of first protrusions are provided at intervals along the length direction of the current collector.

6. The pole piece according to claim 5, characterized in that: The outer contour of the long strip structure is semi-cylindrical or rectangular.

7. The pole piece according to any one of claims 2 to 6, characterized in that: The first protrusion is formed by punching the current collector from a side where the electrode material is provided, or the first protrusion is connected to a surface of the current collector that is away from the electrode material.

8. The pole piece according to any one of claims 1 to 6, characterized in that: A plurality of the first protrusions are arranged at intervals along the length direction and the width direction of the current collector, and a first distance between adjacent first protrusions is greater than or equal to 1 mm and less than or equal to 5 mm.

9. The pole piece according to any one of claims 1 to 6, characterized in that: The height of the first convex portion is greater than or equal to 35 μm and less than or equal to 100 μm.

10. The pole piece according to any one of claims 1 to 4, characterized in that: Along the thickness direction of the pole piece, the projection area of ​​the first convex portion is greater than or equal to 0.196 mm 2 Up to 0.785mm 2 .

11. The pole piece according to any one of claims 1 to 6, characterized in that: The elastic modulus of the current collector is 110 Gpa-130 Gpa.

12. The pole piece according to any one of claims 1 to 6, characterized in that: The pole piece is a negative pole piece.

13. A cylindrical battery, characterized in that: The cylindrical battery comprises: A shell having an opening at one end, comprising a bottom wall opposite to the opening and a side wall connected to the bottom wall; A shell cover, covering the opening; A bare cell is placed in the housing, wherein the bare cell is formed by winding a first pole piece, a separator, and a second pole piece, wherein the first pole piece includes a first current collector and a first electrode material disposed on the first current collector, and the outermost circle of the first current collector along the winding direction includes an empty foil area; Wherein, the empty foil area is provided with at least one first protrusion, the first protrusion protrudes toward the side wall, and the first protrusion is in contact with and electrically connected to the side wall; and / or, the shell is provided with at least one second protrusion, the second protrusion protrudes toward the empty foil area, and the second protrusion is in contact with and electrically connected to the first current collector.

14. The cylindrical battery according to claim 13, characterized in that: The empty foil area further includes a first electrode material, which is arranged on one side of the empty foil area facing the bare battery cell, and the first protrusion is arranged on the other side opposite to the first electrode material along the thickness direction of the empty foil area.

15. The cylindrical battery according to claim 13, characterized in that: Along an axial direction perpendicular to the cylindrical battery, a second distance from the bare battery cell to the battery side wall is greater than or equal to 25 μm and less than or equal to 75 μm.

16. The cylindrical battery according to claim 13, characterized in that: The area of ​​the empty foil region is 1 / 3 to 1 of the area of ​​the outermost circle of the first current collector.

17. The cylindrical battery according to claim 16, characterized in that: The area of ​​the empty foil region is equal to the area of ​​the outermost circle of the current collector, and a line connecting at least two of the first protrusions passes through the winding center.

18. The cylindrical battery according to claim 13, characterized in that: The second pole sheet includes a positive electrode tab, which extends from one end of the second current collector away from the bottom wall. Along the width direction of the first current collector, a third distance between the first protrusion away from one end of the bottom wall and an edge of the first current collector away from one end of the bottom wall is greater than or equal to 0.15 mm.

19. The cylindrical battery according to any one of claims 13 to 18, characterized in that: The second convex portion is a convex point structure or a long strip structure.

20. The cylindrical battery according to any one of claims 13 to 18, characterized in that: The second protrusion is formed by stamping or rolling the shell, or the second protrusion is connected to a side of the shell facing the bare cell.

21. The cylindrical battery according to any one of claims 13 to 18, characterized in that: Along the height direction of the battery, the shell includes a first section and a second section, the first section is a section close to the opening, and the opening area of ​​the first section gradually increases along the direction close to the opening.

22. The cylindrical battery according to any one of claims 13 to 18, characterized in that: The battery includes a support member, which is located at the center of the bare cell and is used to support the bare cell.

23. An electronic device, characterized in that: The electronic device comprises the cylindrical battery according to any one of claims 13 to 22.

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