Full-tab cylindrical battery pole group center hole shaping assembly and tab pre-pressing mechanism thereof

Abstract

The invention discloses a full-tab cylindrical battery pole group center hole shaping assembly, which comprises a shaping bracket, the front end of the central needle is a pointed end, and the central needle is arranged on the shaping bracket; the central needle can be switched between a first depth position and a second depth position in a manner of reciprocating along the axial direction; the forward extending length of the central needle at the second depth position is greater than that of the central needle at the first depth position; the elastic piece is arranged on the shaping bracket; the elastic piece is used for applying elastic force for moving towards the first depth position to the central needle; wherein the central needle is provided with a downward pressing part and a guide part positioned on the front side of the downward pressing part; and a sunken part of which the diameter is smaller than that of the downward pressing part and that of the guiding part is arranged between the downward pressing part and the guiding part.

Description

Technical Field

[0001] This invention relates to the field of lithium battery manufacturing equipment and process technology, and in particular to a center hole shaping assembly for a cylindrical battery electrode assembly with full tabs and its tab pre-pressing mechanism, a core pre-pressing method using the mechanism, and a core manufactured by the mechanism. Background Technology

[0002] Cylindrical tabless batteries (also known as tabless batteries) utilize the blank foil at the tail of the current collector as tabs to directly draw out the current, which greatly increases the current path area and significantly reduces the battery's internal resistance and heat generation. This breaks through the rate performance bottleneck of traditional cylindrical batteries and has become a hot topic in industry research and application.

[0003] In the manufacturing process of all-tab cylindrical batteries, tab shaping (flattening) is a critical step. To facilitate subsequent welding of the current collector plate (current collector segment) to the tabs at the battery end, the vertical tabs (multi-layer blank foil) at the end of the wound core must be flattened into a dense plane. Currently, the mainstream shaping methods in the industry include flattening and pressing. Compared to the risk of metal fragments generated by flattening, the pressing process causes less mechanical damage to the tabs and is safer.

[0004] However, existing flattening or pre-compression technologies mainly focus on the flatness of most areas of the core end face, often neglecting the special characteristics of the core's central hole area. For example... Figure 12 As shown, during the shaping process of the full-tab electrode assembly, the tabs (current collectors) at the central hole are easily pushed inward and piled up, resulting in a disordered state. This disordered pile-up poses a significant safety hazard: the tab foil may be pressed in the reverse direction or, due to springback or improper bending angle, penetrate into the electrode assembly, puncture the separator, and cause direct contact between the positive and negative electrodes, leading to a serious internal short circuit (internal short) problem in the battery. Summary of the Invention

[0005] The main objective of this invention is to provide a center hole shaping assembly for a cylindrical battery electrode group with full tabs and its tab pre-pressing mechanism, which aims to solve the problem of disordered stacking of center hole tabs causing internal short circuits during the shaping process of full tab batteries in the prior art, and to improve the shaping quality of the tab end face.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a center hole shaping assembly for a cylindrical battery electrode group with multiple tabs, comprising: Orthopedic support; A central needle with a pointed tip is mounted on the shaping bracket; the central needle can reciprocate axially between a first depth position and a second depth position; the length of the central needle extending forward when it is in the second depth position is greater than the length of its extension forward when it is in the first depth position. An elastic element is disposed on the shaping bracket; the elastic element is used to apply an elastic force to the central needle to move it toward the first depth position; The center needle has a pressing part and a guide part located in front of the pressing part; a recessed part with a diameter smaller than the pressing part and the guide part is provided between the pressing part and the guide part.

[0007] As one aspect of the invention, the pressing portion includes a pressing surface that protrudes radially outward relative to the guide portion; the outer radial direction of the guide portion gradually increases.

[0008] As one aspect of the present invention, the pressing part is an annular plane perpendicular to the axial direction of the central needle; the guiding part is a cone-shaped part whose outer radial direction gradually increases, and the outer side wall of the cone-shaped part is a guide cone surface.

[0009] As one aspect of the invention, the center pin has a cylindrical body portion with an outer diameter slightly smaller than the inner diameter of the center hole; the recessed portion is located on the front side of the cylindrical body portion and is radially recessed relative to the cylindrical body portion; the pressing surface is the rear sidewall of the recessed portion, and the guide cone surface is the front sidewall of the recessed portion.

[0010] As one aspect of the present invention, the recessed portion is further provided with a cylindrical intermediate body between the pressing surface and the guide cone surface; the sidewall of the cylindrical intermediate body forms the bottom wall of an annular groove.

[0011] As one aspect of the present invention, a spindle insert is provided on the front side of the pressing surface; the tip is disposed at the front end of the spindle insert; and the guide cone is disposed on the side of the spindle insert away from the tip.

[0012] As one aspect of the invention, the spindle insert has a cylindrical expansion portion with an outer diameter equal to that of the cylindrical body portion; the cylindrical expansion portion is located between the guide cone surface and the tip.

[0013] As one aspect of the invention, the other end of the center pin relative to its tip is a connecting end; the connecting end passes through the shaping bracket; the connecting end is fixedly connected to a limiting nut, the limiting nut being located on the rear side of the shaping bracket; the elastic element includes a return spring sleeved outside the connecting end; the return spring is clamped between the limiting nut and the shaping bracket.

[0014] As one aspect of the present invention, the rear end of the cylindrical body is further provided with a limiting step; the limiting step is located on the front side of the support plate; when the center pin is located at the first depth position, the limiting step contacts and limits the shaping support, allowing only the center pin to move forward.

[0015] A pre-compression mechanism for electrode tabs, comprising: The main body base plate has a central guide slot for inserting the battery cell; The pre-compression assembly includes a plurality of compression ribs distributed circumferentially around the center line of the central guide slot; the compression ribs are rotatable about a central axis; A drive plate that can be driven to move, wherein the drive plate is connected to multiple pressure ribs through multiple intermediate connecting rods, and drives the pressure ribs to rotate and switch between a pressed state and a raised state. As described above, the center hole shaping assembly for a cylindrical battery electrode group with full tabs has its center pin facing the center guide slot, and the shaping bracket is fixedly connected between the main body plate and the drive plate.

[0016] As one aspect of the present invention, when the center pin is located at the first depth position, the pressure rib is in the pressed state, and the pressure surface of the pressure rib is flush with the guide portion in the radial direction; when the center pin is pushed forward to the second depth position by the drive plate, the pressure rib rotates to the raised state, and the pressed portion moves forward and inserts into the center hole.

[0017] The present invention also provides a method for pre-pressing a core, wherein the core is formed by stacking and winding a positive electrode sheet, a separator, a negative electrode sheet, and a separator in sequence, and a central hole is left at the central axis of the core. Blank foil without active material is left at the axial ends of the positive electrode sheet and the negative electrode sheet; the blank foil of the positive electrode sheet and the negative electrode sheet are oriented in opposite directions. The core pre-compression method includes: In the first step, the blank foil at least one end of the core is pressed down to form a plurality of grooves that are radially spaced along the inner and outer circumferences of the core. A portion of the blank foil at the radially inner end of at least one of the grooves is guided to be bent once along the axial direction. The second step is to fold the blank foil a second time into the central hole.

[0018] As one aspect of the invention, in the second step, the portion of blank foil bent into the central hole is substantially parallel to the inner wall of the central hole.

[0019] As one aspect of the invention, in the pressing and grooving step, a portion of the blank foil is guided to be bent once axially away from the central hole.

[0020] As one aspect of the present invention, the core preloading method includes: The core is fed into the central guide slot of the tab pre-compression mechanism, and the central pin is inserted into the central hole of the core until the blank foil at the end of the core is flush with the guide in the radial direction. The driving pressure rib presses down on the blank foil at least one end of the core to form multiple grooves, and a portion of the blank foil at the radially inner end of at least one of the grooves is guided by the guide portion to be bent once along the axial direction. The drive center pin moves along the axial center hole, and the lower pressing surface of the center pin bends the blank foil back into the center hole.

[0021] The present invention also provides a core, characterized in that it is prepared by any of the core pre-pressing methods described above.

[0022] As one aspect of the present invention, the core is formed by winding a positive electrode sheet, a separator, a negative electrode sheet, and a separator stacked in sequence. The positive electrode sheet has a positive electrode coating layer and a blank foil located at the axial end of the core. The negative electrode sheet has a negative electrode coating layer and a blank foil located at the axial end of the core. The blank foils of the positive electrode sheet and the negative electrode sheet are oriented in opposite directions. The blank foil of the positive electrode and the blank foil of the negative electrode have a flat surface formed by bending and overlapping towards the central axis of the core, and a plurality of grooves are formed on the flat surface, the grooves being arranged radially at intervals along the inner and outer circumferences of the core; a portion of the blank foil at the radially inner end of at least one of the grooves is bent in the central hole in a direction substantially parallel to the axial direction of the central hole.

[0023] As one aspect of the present invention, the length of the blank foil portion is 0.5 to 5 mm.

[0024] As one aspect of the present invention, the blank foil is composed of multiple layers of blank foil stacked and bent within the central hole.

[0025] As one aspect of the invention, the bent portions of the multilayer blank foil are concentrated adjacent to the groove and extend axially from the bent portions toward the central hole.

[0026] The present invention also provides a cylindrical battery with multiple tabs, comprising the core as described above.

[0027] The beneficial effects of this invention are: This invention provides a center hole shaping assembly for a cylindrical battery electrode pack with all tabs. By setting a pressing part and a guide part located in front of the pressing part on the center pin, and cooperating with the pressing rib, a portion of the blank foil in the center hole area is forcibly guided to bend and guide through the guide part during the bending process, and then pushed vertically into the center hole from the pressing part. This orderly action of "first guiding a bend, then uniformly pressing and bending into the hole" avoids the tabs being squeezed haphazardly, effectively solves the hidden danger of internal short circuit caused by the tabs piercing the separator in the opposite direction, and improves the manufacturing yield and safety of the battery.

[0028] This invention also provides a core pre-compression method. In this method, a plurality of grooves are formed by pressing down on blank foil at at least one end of the core, which are arranged radially and spaced along the inner and outer circumferences of the core. A portion of the blank foil at the radial inner end of at least one of the grooves is guided to be bent once along the axial direction. Then, this portion of blank foil is bent a second time into the central hole. This orderly action of "first guiding a bend, then uniformly pressing down and bending into the hole" avoids the disorderly compression of the tabs, effectively solves the hidden danger of internal short circuit caused by the tabs piercing the separator in the opposite direction, and improves the manufacturing yield and safety of the battery.

[0029] The center hole shaping assembly for a cylindrical battery electrode pack with full tabs provided by this invention achieves step-by-step control of the tab shape by switching the center pin at the first depth position and the second depth position, in conjunction with the action of the pressing rib. At the same time, the recessed part of the shaping mechanism provides the tab with a gathering space and a guide surface, while the pressing surface plays a role in final shaping, ensuring that the tab is tightly attached to the inner wall of the center hole with good consistency, thereby improving the shaping quality of the tab end face. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a three-dimensional structural schematic diagram of the electrode pre-compression mechanism provided in one embodiment of the present invention; Figure 2 yes Figure 1 A schematic diagram showing the mechanism in conjunction with the battery cell; Figure 3 yes Figure 1 A cross-sectional structural diagram in the pre-compression state (the reinforcing rib is raised and the center pin is at the first depth position); Figure 4 yes Figure 3 A schematic diagram of the center pin and the pressure rib state; Figure 5 yes Figure 1 A schematic diagram of the structure of the center hole shaping component of the all-tab cylindrical battery electrode assembly; Figure 6 yes Figure 1 The diagram shows a comparison of the action states of the pre-compression mechanism of the electrode tab during the shaping process. The left image shows the folded state, and the right image shows the shaped state. Figure 7 yes Figure 6 The left image shows an enlarged schematic diagram of the structural orientation of the shaping pole group at the central axis; Figure 8 This is a schematic diagram of the structure of the all-tab cylindrical battery involved in the embodiments of the present invention; Figure 9 yes Figure 8 A schematic diagram of the groove structure on the end face of the winding core; Figure 10 yes Figure 6 The right figure shows an enlarged schematic diagram of the structural orientation of the shaping pole group at the central axis; Figure 11 yes Figure 10 A magnified view of a section at point A in the middle; Figure 12 This is a diagram of the state of the allotal ear electrode assembly after shaping in the existing technology.

[0032] Explanation of reference numerals in the attached figures: 1. Body base plate; 5. Support plate; 15. Connecting rod; 10. Central guide hole groove; 2. Ribs; 14. H-shaped connecting rods; 17. Drive plate; 3. Center pin; 30. Main body; 31. Spindle insert; 310. Expansion part; 311. Tip; 312. Guide cone surface; 36. Recessed part; 361. Pressing surface; 37. Limiting step; 38. Limiting nut; 39. Return spring; 100. Battery cell; 102. Center hole; 110. Partial blank foil. Detailed Implementation

[0033] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0034] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or may be interposed with another element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or may be interposed with another element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementations.

[0035] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0037] Please see Figure 1 , Figure 2 and Figure 3 The present invention provides a tab pre-pressing mechanism with a center hole shaping assembly for a cylindrical battery electrode assembly with full tabs. The tab pre-pressing mechanism is mainly used to pre-press and flatten the end tabs of the full tab core 100, and specifically to guide and shape the tabs at the center hole 102 of the core 100 to prevent internal short circuit.

[0038] The electrode preloading mechanism mainly includes: a main body base plate 1, a preloading assembly, a drive transmission assembly, and a center hole shaping assembly. The main body base plate 1 serves as the mounting base for the electrode preloading mechanism, and its center has a central guide slot 10. The inner diameter of the central guide slot 10 is adapted to the outer diameter of the battery cell (wound core 100) to be processed, and is used for radial positioning of the battery cell during the shaping process. The main body base plate 1 has multiple mounting holes for mounting the shaft mounting body 18. The preloading assembly includes multiple pressure ribs 2 evenly distributed circumferentially around the center line of the central guide slot 10.

[0039] In this embodiment, eight pressure ribs 2 are provided to achieve uniform downward pressure on the end face of the cylindrical core from all directions. Each pressure rib 2 includes a connecting section, a pre-compression section, and a shaft portion located between the two. The pressure rib 2 is hinged to a shaft mounting body on the main body base plate 1 via the shaft portion, thereby allowing it to rotate around the axis of the shaft portion. The rotatable design allows the pre-compression section 21 to press against the end face of the core along a specific trajectory.

[0040] The drive transmission assembly is used to drive the pre-compression action (lifting and pressing down) of the pressure rib 2. The drive transmission assembly includes a drive plate 17 and multiple intermediate connecting rods. In this embodiment, the intermediate connecting rods are H-shaped connecting rods 14. The drive plate 17 is located on the rear side of the main body base plate 1 (the side away from the battery cell) and can be driven by an external drive source (such as a servo motor or cylinder, not shown) to reciprocate along the direction of the center hole line. One end of the H-shaped connecting rod 14 is hinged to the periphery of the drive plate 17 by a pin, and the other end is hinged to the connecting section of the pressure rib 2 by a pin. When the drive plate 17 moves forward or backward, it drives the H-shaped connecting rod 14 to swing, thereby driving the pressure rib 2 to rotate around its axis 20, realizing the switching of the pre-compression section 21 pressing outward (pressing down state) or lifting inward (lifting up state). The drive plate 17 from Figure 6 The state shown in the left image (pressed down) is switched to... Figure 6 The axial travel in the right figure (raised state) is greater than the travel of the center needle 3, that is, greater than the distance the center needle 3 moves between the first depth position and the second depth position.

[0041] Please see Figure 3 , Figure 5 , Figure 10 and Figure 11 The center hole shaping assembly is integrated inside the aforementioned tab pre-compression mechanism and mainly consists of a shaping bracket, a center pin 3, and an elastic element. The shaping bracket includes a bracket plate 5. The shaping bracket mainly includes the bracket plate 5 and connecting rods 15. The bracket plate 5 is fixedly connected to the back side of the main body base plate 1 via multiple connecting rods 15, or as... Figure 3 As shown, the support plate 5 is located between the main body base plate 1 and the drive plate 17. The connecting rod 15 is vertically fixed to the support plate, serving as a support and positioning element. The center pin 3 is positioned along the center hole line and passes through the shaping bracket. The front end of the center pin 3 (the end facing the battery cell) is designed as a pointed tip 311, which facilitates insertion into the center hole 102 of the winding core 100.

[0042] The center pin 3 is not rigidly fixed, but can reciprocate along the axial direction. The first depth position and the second depth position are two axial positions of the center pin 3. The center pin 3 can switch between the first depth position and the second depth position by reciprocating along the axial direction. When the center pin 3 is in the second depth position, the length of its forward extension is greater than the length of its forward extension when it is in the first depth position. That is, the center pin 3 is inserted into the center hole 102 to a deeper depth when it is in the second depth position.

[0043] The center pin 3 has a pressing part and a guide part located in front of the pressing part. A recessed part 36 with a diameter smaller than that of the pressing part is provided between the pressing part and the guide part. When the center pin 3 is at the first depth position, the pressure rib 2 is in the pressed state, and the pressure surface of the pressure rib 2 is flush with the guide part in the radial direction; when the center pin 3 is pushed forward to the second depth position by the drive plate, the pressure rib 2 rotates to the raised state, and the pressing part moves forward and inserts into the center hole.

[0044] In this embodiment, the pressing portion includes a pressing surface that protrudes radially outward relative to the guide portion; further, the pressing portion is an annular plane perpendicular to the axial direction of the center pin 3. The planar pressing portion can better press and bend the electrode tab forward and downward simultaneously, ensuring the consistency of the electrode tab bending. The outer radial direction of the guide portion gradually increases backward, providing a backward bending guide structure. Its outer wall forms a guide surface, which can be a conical surface or a smooth curved surface. Part of the blank foil is bent inward by the pressure rib and extends into the center hole 102, touching the guide portion and being guided backward by the guide portion to form a uniform bending structure, avoiding undesirable bending and collapse.

[0045] Specifically, the center needle 3 is geometrically divided into several functional sections: a spindle insert, a recess 36, and a cylindrical main body 30. The outer diameter of the cylindrical main body is slightly smaller than the inner diameter of the center hole. A conical tip 311 on the spindle insert serves as initial guidance, ensuring the center needle can be smoothly inserted into the center hole 102. The expansion portion 31, located behind the tip 311, has a maximum outer diameter approximately equal to the outer diameter of the main body 30. The cylindrical expansion portion 31 is located between the guide cone surface 312 and the tip 311. The cylindrical expansion portion 31 can be used for coaxial positioning within the center hole 102 and prevents the center hole 102 from being damaged by pressure during the shaping process.

[0046] The guide cone surface 312 is located behind the spindle insert 31, and its outer radial direction gradually decreases rearward (i.e., gradually increases forward), forming a transition slope. The recess 36 is a necked area on the center needle 3, and its maximum outer diameter is significantly smaller than the outer diameter of the cylindrical body 30. The recess 36 is located between the cylindrical body 30 and the spindle insert 31. The recess 36 also has a cylindrical intermediate body between the pressing surface 361 and the guide cone surface 312. The sidewall of the cylindrical intermediate body forms the bottom wall of an annular groove. The annular groove of the recess 36 provides a space for the inward bending of the tab (partial blank foil). The pressing surface 361 is located at the junction of the recess 36 and the cylindrical body 30. The pressing surface 361 is preferably an annular plane perpendicular to the axial direction of the center hole 102. The planar pressing surface 361 functions similarly to the end face of a push rod, used to vertically push the tab gathered in the recess 36 into the center hole 102.

[0047] The lower pressure surface 361 is the front end face (lower end face) of the cylindrical main body 30. A smooth transition surface is provided between it and the side wall of the cylindrical main body 30. Specifically, the smooth transition surface is an arc surface, which can be formed by rounded chamfers. By setting a smooth transition surface, the formation of a vertical corner-shaped surface transition structure can be avoided, thus preventing damage to the tabs or even the winding core when the cylindrical main body 30 is inserted into the central hole 102.

[0048] The cylindrical main body 30 is located behind the lower pressure surface 361. It is a cylindrical structure with an outer diameter slightly smaller than the inner diameter of the central hole 102. It is used to insert into the central hole 102 during the shaping stage to bend the tab and attach it to the inner wall of the central hole 102 as a whole. The connecting end is located at the tail of the central pin 3. The central pin 3 passes through the bracket plate 5 and is used to install the limiting structure and spring.

[0049] For the installation of the elastic element, a limiting nut 38 is fixedly connected to the connecting end, and the limiting nut 38 is located on the rear side of the bracket plate 5 (bracket plate). A limiting step 37 is also provided at the end of the cylindrical body 30 away from the tip, and the limiting step 37 is located on the front side of the bracket plate 5. The elastic element includes a return spring 39 sleeved on the connecting end of the center pin 3. The return spring 39 is sandwiched between the limiting nut 38 and the bracket plate 5 (or the relevant structure of the drive plate 17). While sandwiched between the limiting nut 38 and the bracket plate 5, the return spring 39 is in a compressed state, always tending to push the center pin 3 backward.

[0050] In this embodiment, the elastic element is used to apply an elastic force to the center pin to move it to a first depth position (or maintain its tendency to move backward). The center pin 3 is slidable relative to the shaping bracket. When there is no external force (or under specific operating conditions), the center pin 3 is in a standby state under the constraint of the limiting structure. The drive plate 17 from Figure 6 Switching to left image Figure 6 In the state shown in the right figure, the axial travel is greater than the travel of the center needle 3, that is, greater than the distance the center needle 3 moves between the first depth position and the second depth position.

[0051] This invention also provides a method for manufacturing a core using the aforementioned tab pre-compression mechanism, which includes a core pre-compression method. Before tab pre-compression, the wound full-tab core 100 can be fed into the tab pre-compression mechanism, with its ends inserted into the center guide groove 101 hole 10 of the body base plate 1. At this time, the tip 311 of the center needle 3 and the spindle insert 31 are inserted into the center hole 102 of the core 100.

[0052] Please combine Figures 1 to 10 As shown, the core pre-compression method mainly includes the following steps: In the first step, the blank foil at least one end of the core 100 is pressed down to form a plurality of grooves 101 arranged radially from the inner circumference to the outer circumference of the core 100. A portion of the blank foil 110 at the radially inner end of at least one groove 101 is guided to be bent once along the axial direction. The second step is to fold the blank foil 110 into the central hole 102 a second time.

[0053] like Figure 3 , Figure 10 , Figure 11 As shown, the drive mechanism pushes the drive plate 17 backward, which, through the H-shaped connecting rod 14, drives the pressure rib 2 towards the end face of the core 100 to press down the blank foil until it is pressed into place, forming the groove 101101. At this time, the return spring 39 is in the overall released state, and the center pin 3 is pushed by the return spring 39, in the "first depth position". In this position, the forward extension length of the center pin 3 is relatively short. The first depth position can be regarded as the initial position of the center pin 3.

[0054] When the rib 2 moves to the pre-compression position, it is located Figure 6 As shown in the left figure, the pressing surface (pre-pressing section 21) of the pressing rib 2 is exactly flush with the recessed portion 36 of the center pin 3 in the radial direction, and is directly opposite the recessed portion 36 in the radial direction. Furthermore, it is directly opposite the guide cone surface that serves as the front sidewall of the recessed portion 36.

[0055] During the pre-pressing process, the pressing surface of the pressing rib 2 presses down on the tabs (blank foil) at the end face of the core 100. Under pressure, the tabs collapse to form grooves 101. Due to the compression of the pressing rib 2, a portion of the blank foil 110 (pole assembly) near the center hole is squeezed towards the center hole 102. At this time, this portion of the blank foil 110 encounters and contacts the center pin 3. Due to the presence of the guide cone surface 312, this portion of the blank foil 110 will not be stuck, but rather... Figure 7 As shown, guided by the guide cone surface 312, it enters the annular groove space of the recessed part 36 and is guided to extend and converge backward, forming a bend.

[0056] like Figure 7 As shown, the portion of blank foil 110 entering the recess 36 contacts the guide cone surface 312 below. The guide cone surface 312 acts as a bevel guide, forcing the electrode assembly to deform upwards (away from the tip direction) and extend axially within the recess 36. In this step, the electrode assembly forms a "single bend" state: the electrode lug body lies down on the end face of the core 100 to form a groove 101, while the electrode lugs at the edge of the center hole 102 are housed in the neck-shaped recess of the center needle 3, and are in a... Figure 7 The structure shown is upright, without blocking the central hole 3, and without any disordered or intersecting structures.

[0057] like Figure 4 , Figure 6Right picture Figure 10 , Figure 11 As shown, after the pre-pressing is completed, the drive mechanism reverses the drive plate 17 to move forward, and the drive plate 17 lifts the pressure rib 2, causing the pressure rib 2 to move away from the electrode tab. At this time, the center pin 3 moves forward axially and switches to the "second depth position". As the pressure rib 2 is lifted, the cylindrical body 30 of the center pin 3 and the lower pressure surface 361 move forward (downward) relative to the core 100. During this process, the lower pressure surface 361 acts like a piston, pressing vertically downward onto the portion of blank foil 110 that was just stuck in the annular groove of the recess 36. Since the lower pressure surface 361 is a flat annular surface, it pushes the portion of blank foil 110 downward evenly into the center hole 102. At the same time, the cylindrical structure 30 that follows immediately is inserted into the center hole 102. This portion of blank foil 110 is "ironed" flat by the outer wall of the cylindrical body 30 and the inner wall of the center hole 102. Finally, this part of the tab (part of the blank foil 110) is attached to the inner wall of the central hole, with its direction parallel to the axis of the central hole 3 and pointing towards the inside of the battery, forming a secondary bend.

[0058] In summary, during the entire pre-pressing process, when the pressing rib 2 is pressed down, the center pin 3 retracts (or is positioned relatively backward), and the recessed part 36 receives the blank foil 110; when the pressing rib 2 is lifted, the center pin 3 is inserted (or is positioned relatively forward), and the pressing surface 361 of the stepped surface pushes the blank foil 110 into the hole.

[0059] Please see Figure 8 and Figure 9 .like Figure 8 In one embodiment of the present invention, the structure of a cylindrical battery with multiple tabs is described. The core 100 is formed by winding a positive electrode sheet, a separator, a negative electrode sheet, and a separator in sequence, forming a cylindrical shape. In an optional embodiment, the positive active material layer covers most of the positive electrode foil, and the negative active material layer covers most of the negative electrode foil. When unfolded, the positive and negative electrode sheets form the aforementioned blank foil at both ends in the width direction (i.e., the positions where the active material is not coated). Taking the positive electrode sheet as an example, the position on the positive electrode foil where the positive active material layer is not coated forms the first blank foil. Of course, the portion on the negative electrode foil where the negative active material is not coated forms the second blank foil (located at the end of the core 100 away from the first blank foil). When the core 100 is wound, the positive and negative active material layers (not shown in the figure) are staggered in the axial direction so that the blank foils of the positive and negative electrode sheets face opposite directions when wound into the core 100. The upper and lower end faces (the lower end face is not shown) are pressed into flat surfaces 111 by a flattening device.

[0060] like Figure 8 , Figure 9As shown, the core 100 is housed in the battery casing (not shown) while immersed in electrolyte. The positive electrode foil can be a metal foil made of aluminum or aluminum alloy, and the negative electrode foil can be a metal foil made of copper or copper alloy.

[0061] like Figure 9 As shown, in an optional embodiment, the core 100 has a central hole 102, which is used to insert a positioning pin (not shown) for welding the current collector 112 and the bottom of the battery casing. The positive and negative blank foils are bent into a flat surface 111, with the bending direction from the outer periphery of the core 100 towards the central hole 102. Adjacent blank foils of the positive or negative electrode are bent overlapping each other. In the industry, it is generally required that, viewed along the axial direction of the core 100, the blank foils on the flat surface 111 overlap at least four times to ensure sufficient welding strength between the flat surface 111 and the current collector 112. If the overlap exceeds 16 times, it will cause severe accumulation of the inner peripheral tabs, requiring more foil material to be accommodated in the inner ring's multiple bending areas, increasing the pressure on the bottom material area, posing a risk of material loss, and also posing a risk of internal short circuits in the battery due to tab insertion, potentially causing a serious accident. Figure 1 As shown, in an optional embodiment, the current collector 112 is divided into a positive current collector and a negative current collector. The positive current collector is welded to the flat surface 111 formed by the positive electrode blank foil. The positive current collector can be a metal plate or sheet made of aluminum, aluminum alloy monomers, or composite materials. The negative current collector is welded to the flat surface 111 formed by the negative electrode blank foil. The negative current collector can be a metal plate or sheet made of nickel, nickel alloy, copper, copper alloy monomers, or composite materials. A hole is provided near the center of the positive current collector 112, and the position of the hole corresponds to the position of the central hole 102. The negative current collector can be a single circular current collector or a circular current collector with a circular protrusion in the center. The center of the current collector 112 at the negative electrode end is further welded to the bottom of the battery casing by an externally inserted positioning pin.

[0062] It is understood that in this invention Figure 8 , Figure 9 These are merely illustrative diagrams; the actual number of layers in the core 100 is subject to the embodiments. In an optional embodiment, the positive electrode active material layer comprises any one or more positive electrode materials capable of lithium insertion and extraction. The positive electrode active material layer may further comprise any one or more other materials such as a positive electrode binder and a positive electrode conductive agent. The positive electrode material can be lithium iron phosphate, nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, or other existing lithium-ion battery positive electrode materials.

[0063] In an optional embodiment, the negative electrode material can be a carbon material, such as artificial graphite and natural graphite, or a graphite-based composite negative electrode material doped with a certain amount of silicon oxide or silicon carbon, as well as other existing lithium-ion battery negative electrode materials.

[0064] In an optional embodiment, the separator can be a single-layer PP, single-layer PE, double-layer PP / PE, double-layer PP / PP, or triple-layer PP / PE / PP separator; the separator can also be a porous membrane coated with ceramic particles, preferably Al2O3 or boehmite; the separator can also be other lithium-ion battery separator materials that are already available in the prior art.

[0065] In an optional embodiment, the electrolyte comprises a solvent and an electrolyte salt. In addition, the electrolyte may further comprise one or more of other materials, such as additives.

[0066] In an optional embodiment, the aforementioned solvent comprises any one or more non-aqueous solvents such as organic solvents. The non-aqueous solvent electrolyte is a so-called non-aqueous electrolyte, and the non-aqueous solvent may be, for example, cyclic carbonates, chain carbonates, lactones, chain carboxylic esters, nitriles (mononitriles), etc.

[0067] In an optional embodiment, the aforementioned electrolyte salt may comprise one or more of salts such as lithium salts. Alternatively, the electrolyte salt may also comprise salts other than lithium salts. These salts other than lithium salts may be, for example, light metal salts other than lithium.

[0068] In one embodiment, the battery casing is a metal casing, which can be a steel casing, an aluminum casing, or more preferably a steel casing. In one embodiment, the battery type is preferably an 18650 or 21700 cylindrical battery, but the present invention is not limited to the above two types of cylindrical batteries.

[0069] In an optional embodiment, the aforementioned lithium salt is, for example, lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium tetraphenylborate (LiB(C6H5)4), lithium methanesulfonate (LiCH3SO3), lithium trifluoromethanesulfonate (LiCF3SO3), lithium tetrachloroaluminate (LiAlCl4), lithium hexafluorosilicate (Li2SF6), lithium chloride (LiCl), and lithium bromide (LiBr). The aforementioned lithium salt can be any one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, and lithium hexafluoroarsenate; more preferably, it includes lithium hexafluorophosphate. The content of the electrolyte salt is not particularly limited, but preferably it is 0.3 mol / kg to 3 mol / kg relative to the solvent.

[0070] The blank foil on the flat surface 111 and the blank foil in the groove are continuous and have not been cut using a cutting device. The groove is obtained by pressing down the pressure claw of the flattening device.

[0071] As described in the prior art, the circumferential dimension of the blank foil before and after bending is reduced due to the inward bending of the positive or negative blank foil, which easily causes wrinkles on the flat surface 111, making it difficult to weld the flat surface 111 and the corresponding current collector 112.

[0072] To solve the above problems, such as Figures 2-6 As shown, this embodiment provides a core 100, in which the wrinkles on the flat surface 111 of the core 100 are significantly reduced, significantly improving the flatness of the flat surface 111 and improving the welding quality between the flat surface 111 and the current collector 112. Figures 2 to 6 As shown, the flat surface 111 has grooves 101 formed thereon, and the grooves 101 are arranged radially and spaced along the inner and outer peripheries of the core 100 on the flat surface 111; the number of grooves 101 on the flat surface 111 is 8.

[0073] Generally, the number of slots 101 can be either symmetrical or evenly divided into circumferences. Typically, the number of slots 101 should be greater than or equal to 4. Different numbers of slots 101 can be selected, such as 4, 5, 6, 8, 9, 10, or 12. All point values ​​or ranges greater than or equal to 4 and less than or equal to 12 are within the protection scope of this optional embodiment. Specifically, based on the dimensions of commonly used core 100 models, the number of slots in this optional embodiment can be selected as 6 or 8.

[0074] It should be noted that the groove 101 and the flat surface 111 are formed on a flattening device that includes the aforementioned tab pre-compression mechanism.

[0075] Based on the above-described tab pre-compression mechanism and core pre-compression method, this invention manufactures a core 100. Please refer to... Figure 8 and Figure 9 The core 100 is formed by sequentially stacking and winding a positive electrode sheet, a separator, and a negative electrode sheet. A central hole 102 is provided at the central axis. Uncoated blank foil (current collector) is left at the axial ends of both the positive and negative electrode sheets. The positive blank foil (usually aluminum foil) and the negative blank foil (usually copper foil) are located at the two ends of the core, respectively.

[0076] After being pressed by the rib 2, the blank foil at the end of the core forms a dense, flat surface 111. On the flat surface 111, a plurality of (eight in this embodiment) radially spaced grooves 101 are formed. These grooves 101 extend from the inner periphery of the core to the outer periphery.

[0077] Please see Figure 10and Figure 11 At the radial inner end of the groove 101, near the central hole 102, a portion of the blank foil (i.e., the aforementioned partial blank foil 110) is not laid flat like the end face tab, but is bent inward into the central hole 102. This portion of the blank foil 110 is arranged in a direction substantially parallel to the axial direction of the central hole, closely adhering to the inner wall of the central hole 102. The length of this portion of the blank foil 110 is generally controlled between 0.5mm and 5mm. This portion of the blank foil 110 consists of multiple layers of blank foil stacked and bent within the central hole 102. The bent portions of the multiple layers of blank foil (partial blank foil 110) are concentrated adjacent to the groove 101, and extend axially into the central hole 102 from the bent portions. The multiple layers of blank foil are neatly arranged, without burrs or random crossings.

[0078] Any numerical values ​​cited herein include all values ​​ranging from a lower limit to an upper limit, increasing by one unit, with at least two units between any lower and any higher value. For example, if the quantity of a component or the value of a process variable (e.g., temperature, pressure, time, etc.) is described as being from 1 to 90, preferably from 20 to 80, more preferably from 30 to 70, the purpose is to illustrate that values ​​such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 are also explicitly listed in this specification. For values ​​less than 1, a unit is appropriately considered to be 0.0001, 0.001, 0.01, 0.1, etc. These are merely examples intended for explicit expression, and it can be assumed that all possible combinations of values ​​listed between the minimum and maximum values ​​are explicitly described in this specification in a similar manner.

[0079] Unless otherwise stated, all ranges include the endpoints and all numbers between them. The terms "approximately" or "about" used with ranges apply to both endpoints of the range. Thus, "approximately 20 to 30" is intended to cover "approximately 20 to approximately 30," including at least the specified endpoints.

[0080] All articles and references disclosed herein, including patent applications and publications, are incorporated herein by reference for various purposes. The term “substantially constitutes…” used to describe a combination should include the identified elements, components, parts, or steps, as well as other elements, components, parts, or steps that do not substantially affect the essential novelty of the combination. The use of the terms “comprising” or “including” to describe combinations of elements, components, parts, or steps herein also contemplates embodiments substantially constituted by such elements, components, parts, or steps. The use of the term “may” herein is intended to indicate that any described attribute included by “may” is optional.

[0081] Multiple elements, components, parts, or steps can be provided by a single integrated element, component, part, or step. Alternatively, a single integrated element, component, part, or step can be divided into multiple separate elements, components, parts, or steps. The use of "a" or "an" to describe an element, component, part, or step does not imply the exclusion of other elements, components, parts, or steps.

[0082] It should be understood that the above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this teaching should not be determined by reference to the above description, but rather by reference to the appended claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the inventors have not considered that subject matter as part of the disclosed inventive subject matter.

Claims

1. A center hole shaping assembly for a cylindrical battery electrode group with multiple tabs, wherein, include: Orthopedic support; A central needle with a pointed tip is mounted on the shaping bracket; the central needle can reciprocate axially between a first depth position and a second depth position; the length of the central needle extending forward when it is in the second depth position is greater than the length of its extension forward when it is in the first depth position. An elastic element is disposed on the shaping bracket; the elastic element is used to apply an elastic force to the central needle to move it toward the first depth position; The center needle has a pressing part and a guide part located in front of the pressing part; a recessed part with a diameter smaller than the pressing part is provided between the pressing part and the guide part.

2. The center hole shaping assembly for a cylindrical battery electrode group with multiple tabs as described in claim 1, wherein, The pressing portion includes a pressing surface that protrudes radially outward relative to the guide portion; the outer radial direction of the guide portion gradually increases.

3. The center hole shaping assembly for a cylindrical battery electrode group with multiple tabs as described in claim 2, wherein, The pressing part is an annular plane perpendicular to the axis of the center needle; the guiding part is a cone that gradually increases in size from the outer radial direction, and the outer wall of the cone is a guide cone surface.

4. The center hole shaping assembly for a cylindrical battery electrode group with multiple tabs as described in claim 3, wherein, The central pin has a cylindrical body portion with an outer diameter slightly smaller than the inner diameter of the central hole; the recessed portion is located on the front side of the cylindrical body portion and is radially recessed relative to the cylindrical body portion; the pressing surface is the rear sidewall of the recessed portion, and the guide cone surface is the front sidewall of the recessed portion.

5. The center hole shaping assembly for a cylindrical battery electrode group with multiple tabs as described in claim 4, wherein, The recessed portion is further provided with a cylindrical intermediate body between the pressing surface and the guide cone surface; the side wall of the cylindrical intermediate body forms the bottom wall of the annular groove.

6. The center hole shaping assembly for a cylindrical battery electrode group with multiple tabs as described in claim 2, wherein, A smooth transition surface is provided between the pressing surface and the side wall of the cylindrical main body.

7. The center hole shaping assembly for a cylindrical battery electrode group with multiple tabs as described in claim 5, wherein, A spindle insert is provided on the front side of the pressing surface; the tip is provided at the front end of the spindle insert; the guide cone is provided on the side of the spindle insert away from the tip; the spindle insert has a cylindrical expansion portion with an outer diameter equal to that of the cylindrical main body; the cylindrical expansion portion is located between the guide cone and the tip.

8. The center hole shaping assembly for a cylindrical battery electrode group with multiple tabs as described in claim 7, wherein, The center pin has a connecting end opposite its tip; the connecting end passes through the shaping bracket; the connecting end is fixedly connected to a limiting nut, which is located on the rear side of the shaping bracket; the elastic element includes a return spring sleeved outside the connecting end; the return spring is sandwiched between the limiting nut and the shaping bracket.

9. The center hole shaping assembly for a cylindrical battery electrode group with multiple tabs as described in claim 7, wherein, The rear end of the cylindrical body is also provided with a limiting step; the limiting step is located on the front side of the support plate; when the center pin is at the first depth position, the limiting step contacts and limits the shaping support, allowing only the center pin to move forward.

10. A pre-compression mechanism for electrode tabs, wherein, include: The main body base plate has a central guide slot for inserting the battery cell; The pre-compression assembly includes a plurality of compression ribs distributed circumferentially around the center line of the central guide slot; the compression ribs are rotatable about a central axis; A drive plate that can be driven to move, wherein the drive plate is connected to multiple pressure ribs through multiple intermediate connecting rods, and drives the pressure ribs to rotate and switch between a pressed state and a raised state. The center hole shaping assembly for a cylindrical battery electrode group with full tabs as described in any one of claims 1 to 9, wherein the center pin of the center hole shaping assembly for a cylindrical battery electrode group with full tabs faces the center guide slot, and the shaping bracket is fixedly connected between the body base plate and the drive plate.

11. The electrode pre-compression mechanism as described in claim 10, wherein, When the center pin is at the first depth position, the pressure rib is in the pressed state, and the pressure surface of the pressure rib is flush with the guide part in the radial direction; when the center pin is pushed forward to the second depth position by the drive plate, the pressure rib rotates to the raised state, and the pressed part moves forward and inserts into the center hole.

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