Extrusion tool and extrusion air exhaust system

Abstract

The utility model provides an extrusion tool and an extrusion air exhaust system, and belongs to the technical field of lithium battery production. The extrusion tool comprises an extrusion assembly and a driving assembly, the extrusion assembly comprises two extrusion rollers, the axes of the extrusion rollers extend in the first direction, the two extrusion rollers are spaced in the second direction, the first direction and the second direction are both horizontal and perpendicular to each other, and a containing space is formed between the two extrusion rollers and used for containing a single battery; the driving assembly is matched with the extrusion assembly and comprises an extrusion driving part and a lifting driving part, the extrusion driving part drives the two extrusion rollers to get close to or get away from each other in the second direction, and the lifting driving part drives the extrusion rollers to reciprocate in the vertical direction. The extrusion tool can upwards push and extrude the high-concentration electrolyte at the bottom of the electrode assembly, so that the electrolyte forms convection, the distribution condition of the electrolyte in the electrode assembly is improved, bubbles are promoted to be discharged upwards, the cycling stability of a battery monomer is improved, and the service life of the battery monomer is prolonged.

Description

Technical Field

[0001] This application relates to the field of lithium battery production technology, and more specifically, to an extrusion tooling and an extrusion degassing system. Background Technology

[0002] In recent years, lithium battery production technology has been continuously improving. However, during the production process of lithium batteries, the electrolyte concentration varies inside the battery. Generally speaking, the electrolyte concentration in the center of the electrode assembly is often much lower than that at the edges of the electrode assembly. It is difficult for the electrolyte to be quickly replenished to the center through concentration gradient diffusion, thus affecting the battery's lifespan. Utility Model Content

[0003] This application provides an extrusion fixture and an extrusion degassing system, which helps to improve the distribution of electrolyte in the electrode assembly and enhance the cycle stability and service life of the battery cell.

[0004] In a first aspect, embodiments of this application provide an extrusion fixture, including an extrusion assembly and a drive assembly. The extrusion assembly includes extrusion rollers, the axis of which extends along a first direction. There are two extrusion rollers spaced apart along a second direction. Both the first and second directions are horizontal and perpendicular to each other. A receiving space is formed between the two extrusion rollers for accommodating a single battery cell. The drive assembly cooperates with the extrusion assembly and includes an extrusion drive component and a lifting drive component. The extrusion drive component drives the two extrusion rollers to move closer or further apart along the second direction, and the lifting drive component drives the extrusion rollers to reciprocate along the vertical direction.

[0005] In the above technical solution, the extrusion rollers of the extrusion fixture extrude the battery cell vertically from bottom to top, which effectively pushes the high-concentration electrolyte at the bottom of the electrode assembly upwards. This causes the electrolyte to convect within the electrode assembly, improving its distribution and solving the problem of excessively high electrolyte concentration at the edges due to uneven electrolyte distribution, which easily leads to lithium plating. This improves the performance stability and lifespan of the battery cell. At the same time, the extrusion action also causes the bubbles generated during the formation process to be discharged upwards, reducing the possibility of local current density imbalance and uneven SEI film growth, thus improving the cycle stability and lifespan of the battery cell.

[0006] In some embodiments, the outer peripheral surface of the extrusion roller includes an extrusion surface, which is a rotating surface. The outer contour of the cross-section of the extrusion surface is circular, and the radius of the cross-section of the extrusion surface gradually increases from both ends to the middle along the axial direction of the extrusion roller.

[0007] In the above technical solution, the cross-section of the extrusion roller is circular, and the arc-shaped contour of the extrusion roller along the second direction fits better with the surface of the shell. This can reduce the uneven instantaneous migration of electrolyte caused by local pressure concentration, further enhance the global convection of electrolyte, and improve the efficiency of bubble discharge.

[0008] In some embodiments, the outer peripheral surface of the extrusion roller includes an extrusion surface, which is configured as an elastic surface.

[0009] In the above technical solution, the extrusion surface is configured as an elastic surface, so that the extrusion surface of the extrusion roller can form a surface contact extrusion with the surface of the shell, which can improve the uniformity of the contact area and pressure distribution. The rebound characteristics of the elastic surface generate a reverse thrust during extrusion rebound, which causes the shell deformation to reset, which can enhance the driving force for bubbles to leave the interface and improve the bubble discharge efficiency.

[0010] In some embodiments, the extrusion roller includes a rigid portion and an elastic portion, the elastic portion being sleeved outside the rigid portion and defining the extrusion surface of the extrusion roller.

[0011] In the above technical solution, the extrusion roller better fits the surface of the battery cell casing during extrusion, improving the extrusion effect on the casing, thereby promoting the convection of electrolyte and improving the uniformity of electrolyte distribution in the electrode assembly.

[0012] In some embodiments, the outer contour of the extrusion roller is circular, the outer contour of the rigid part is non-circular, and the inner circumferential surface shape of the elastic part matches the outer circumferential surface shape of the rigid part.

[0013] In the above technical solution, the non-circular outer contour of the rigid part increases the connection stability between the rigid part and the elastic part, so that the rigid part and the elastic part of the extrusion roller maintain a tight fit during the extrusion process and will not rotate relative to each other due to shape mismatch, thereby improving the operational stability of the pressure tooling.

[0014] In some embodiments, the elastic portion is of uniform wall thickness.

[0015] In the above technical solution, the elastic part is of uniform wall thickness, which makes the extrusion pressure relatively uniform, thereby reducing problems such as local damage to the shell caused by uneven extrusion pressure, improving the uniformity of the overall extrusion effect, and improving the efficiency of bubble discharge.

[0016] In some embodiments, the two extrusion rollers have the same structure and are arranged symmetrically.

[0017] In the above technical solution, the two structures are identical and axially symmetrically arranged. The shell will not be damaged by the pressure difference on both sides during the extrusion process, and it can improve the stability of the extrusion force and the extrusion effect, promote electrolyte convection, and improve the uniformity of electrolyte distribution in the electrode assembly.

[0018] In some embodiments, the extrusion fixture is configured such that the extrusion rollers apply an extrusion force of 0.1 MPa to 0.6 MPa to the battery cell.

[0019] In the above technical solution, the extrusion pressure is 0.1MPa-0.6MPa, which can improve the extrusion effect, promote electrolyte convection, and improve the uniformity of electrolyte distribution in the shell.

[0020] In some embodiments, the drive assembly includes a rotational support, with rotational supports provided at both ends of the axial direction of each extrusion roller, and the rotational supports at both ends of the extrusion roller are rotatably provided on both sides.

[0021] In the above technical solution, the axial ends of the extrusion roller are provided with rotational supports to keep the extrusion roller stable during rotation, which can reduce swaying and deviation.

[0022] In some embodiments, the lifting drive component includes a lifting unit that drives each rotating support to lift and lower, and the compression drive component drives the rotating support to move relative to the lifting unit in a second direction.

[0023] In the above technical solution, the extrusion drive component drives the rotating support to move relative to the lifting unit in the second direction, which makes it easy to control the extrusion pressure of the extrusion roller on the shell and improve the extrusion effect. The extrusion drive component does not need to drive the lifting unit to move, which can reduce the driving energy consumption.

[0024] In some embodiments, the drive assembly further includes an adjustment component for adjusting the spacing between the two extrusion rollers along a second direction; the lifting drive component includes a lifting unit that drives each rotational support to lift, and the adjustment component drives the lifting unit to move along the second direction.

[0025] The above technical solution has a simple overall structure, is easy to implement, and has a wide range of adjustable dimensions, which is conducive to the processing of more types of battery cells.

[0026] In some embodiments, the drive assembly further includes a limiting device for limiting the extreme lifting positions of the extrusion roller.

[0027] In the above technical solution, the limiting device can limit the stroke of the extrusion roller to extrude the shell, thereby concentrating the extrusion force on the shell area corresponding to the active material layer of the electrode, avoiding ineffective extrusion on the shell area corresponding to the tab and the tab connection area, so that the extrusion is applied to the key area of ​​electrolyte distribution and the extrusion efficiency is improved.

[0028] In some embodiments, the drive assembly further includes a vibration drive component that drives the extrusion roller to vibrate along a second direction.

[0029] In the above technical solution, the vibration drive component drives the extrusion roller to vibrate along the second direction, which enables the trapped bubbles to migrate quickly to the exhaust channel, significantly improving the bubble discharge efficiency, realizing the rapid and complete detachment of bubbles, thereby shortening the mixing time of additives in the electrolyte, rapidly reducing the distribution difference of the electrolyte, and improving production efficiency.

[0030] In some embodiments, the extrusion fixture is used to extrude a battery cell including a housing and an electrode assembly disposed within the housing. The electrode assembly includes stacked positive and negative electrode sheets and a separator, and the stacking thickness direction of the electrode assembly is consistent with the second direction.

[0031] In the above technical solution, the extrusion roller is driven by the lifting drive component to reciprocate in the vertical direction, thereby achieving periodic extrusion of the electrode assembly housing from bottom to top, which promotes the uniform distribution of electrolyte in the electrode assembly during the formation process, facilitates the full discharge of air bubbles in the battery cell, and improves the cycle stability and service life of the battery cell.

[0032] Secondly, embodiments of this application also provide a compression suction system, including a suction fixture and the aforementioned compression fixture, wherein the suction fixture is used to extract air from a battery cell.

[0033] The extrusion and degassing system according to an embodiment of this application includes a degassing fixture and the extrusion fixture described above. The degassing fixture is used to degas the battery cell and can effectively coordinate the extrusion and degassing actions to accelerate the bubble discharge rate and improve the cycle stability and service life of the battery cell. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram illustrating the usage state of the extrusion tooling provided in some embodiments of this application;

[0036] Figure 2 A side view showing the extrusion tooling in use according to some embodiments of this application;

[0037] Figure 3 A schematic diagram of an extrusion roller provided in some embodiments of this application;

[0038] Figure 4 Cross-sectional views of the extrusion rollers provided in some embodiments of this application;

[0039] Figure 5 for Figure 4 A schematic cross-sectional view of the extrusion roller shown;

[0040] Figure 6 A top view showing the extrusion tooling in use according to some embodiments of this application;

[0041] Figure 7 This is a schematic diagram illustrating the usage state of the extrusion pumping system provided in some embodiments of this application.

[0042] Figure label:

[0043] 1000 compression vacuum system;

[0044] 200 vacuum extraction fixtures;

[0045] Extrusion fixture 100; First direction X; Second direction Y;

[0046] Battery cell 1; casing 11; electrode assembly 12;

[0047] Extrusion component 2;

[0048] Extrusion roller 21; rigid part 211; elastic part 212; extrusion surface 213; end 2131; middle part 2132;

[0049] Accommodation space 22; Axis S;

[0050] Drive assembly 3;

[0051] Extrusion drive component 31; lifting drive component 32; lifting unit 321;

[0052] Vibration drive component 33;

[0053] Adjusting component 34; Limiting device 35;

[0054] Rotary support 36; support base 361; bearing 362;

[0055] Sliding base 38; Fixed base 39. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0057] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0058] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0059] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0060] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0061] In this application, "multiple" means two or more (including two).

[0062] In this application, the battery cell may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and the embodiments of this application are not limited to these. The battery cell includes a casing, electrode components, and an electrolyte. The casing is used to house the electrode components and the electrolyte. The electrode components consist of a positive electrode, a negative electrode, and a separator. The battery cell mainly operates by the movement of metal ions between the positive and negative electrode components. The positive electrode includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector, and the positive current collector without the positive active material layer protrudes beyond the positive current collector with the positive active material layer, serving as the positive electrode tab. Taking a lithium-ion battery as an example, the material of the positive current collector can be aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector, and the negative current collector without the negative active material layer protrudes from the one coated with the negative active material layer. The negative current collector without the negative active material layer serves as the negative electrode tab. The material of the negative current collector can be copper, and the negative active material can be carbon or silicon, etc. To ensure that a large current can be passed without melting, there are multiple positive electrode tabs stacked together, and there are multiple negative electrode tabs stacked together. In addition, the electrode assembly can be a wound structure or a stacked structure, and the embodiments of this application are not limited to these.

[0063] The production process of a single battery cell involves a segmented electrolyte injection process, typically in the following sequence: primary electrolyte injection → static wetting → formation → secondary electrolyte injection → sealing. The core principle is that the primary electrolyte injection provides the foundation for film formation, completing the SEI film (Solid Electrolyte Interphase). The secondary electrolyte injection then replenishes the electrolyte and optimizes performance. Primary electrolyte injection: 60%–85% of the total electrolyte volume is injected, usually containing film-forming additives (such as vitamin C). After injection, vacuum standing / high-temperature activation (e.g., 45–50°C, several hours) is required to ensure the electrolyte fully wets the electrodes and separator, and to remove air bubbles. Formation: The first charge (mainly with a small current) forms a stable SEI film on the negative electrode. This process is irreversible and consumes a small amount of electrolyte and lithium, while also generating gas. Venting: After formation, vacuum / negative pressure venting is usually required to remove the gases generated during the reaction, preventing excessive internal pressure from affecting performance and safety. Secondary electrolyte filling: Replenishing electrolyte lost due to formation, decomposition, and venting, bringing the total amount back to the design value. Functional additives (such as flame retardants and low-temperature optimization components) can be added as needed. Subsequent processes: After secondary electrolyte filling, the battery can be left to stand, undergo secondary formation, or age. Finally, it is sealed, capacity tested, and inspected to ensure the stable performance of the individual cells.

[0064] However, due to the consumption during formation and the significant difference in electrolyte concentration between the first and second electrolyte injections, the electrolyte concentration in the central part of the electrode assembly is often far less than that at the edges. This makes it difficult for the electrolyte to be quickly replenished to the central position through concentration gradient diffusion. During the formation process, electrochemical reactions generate gas, which often cannot be fully expelled in time. Some gas remains within the electrode assembly, located at the interface between the electrode and the separator, and within the pores of the active material layer. This disrupts the interfacial stability between the electrode assembly and the electrolyte, hindering electrolyte wetting to the central position and further exacerbating the electrolyte scarcity problem. This amplifies the concentration difference between the electrolyte concentration at the edges and the center of the electrode assembly. A high electrolyte concentration worsens the lithium plating window. Because the electrolyte concentration at the edges of the electrode assembly is much higher than that at the center, lithium plating is more likely to occur at the edges during battery cell cycling. In addition, trapped air bubbles can cause problems such as local current density imbalance and uneven SEI film growth, which ultimately manifest as the risk of battery cell cycle failure during its service life. These multiple defects urgently need to be addressed.

[0065] To address the above issues, this application proposes an extrusion fixture. During the battery cell production process, extrusion of the battery cell improves the uniformity of electrolyte distribution, pushing the electrolyte from the bottom of the electrode assembly upwards to the center, thus enhancing the uniformity of electrolyte distribution within the electrode assembly and resolving the problem of high electrolyte concentration at the bottom of the electrode assembly leading to lithium plating. Furthermore, extrusion effectively removes air bubbles from within the battery cell, thereby addressing issues such as localized current density imbalances and uneven SEI film growth. In summary, this can improve the overall lifespan of the battery cell.

[0066] Hereinafter, with reference to the accompanying drawings, the extrusion tooling 100 and the extrusion degassing system 1000 according to embodiments of the present invention will be described.

[0067] refer to Figure 1 and Figure 2 , Figure 1 This is a schematic diagram illustrating the usage state of the extrusion tooling provided in some embodiments of this application. Figure 2This is a side view of the extrusion fixture 100 in use according to some embodiments of this application. The extrusion fixture 100 includes an extrusion assembly 2 and a drive assembly 3. The extrusion assembly 2 includes extrusion rollers 21, the axis of which extends along a first direction X. There are two extrusion rollers 21 spaced apart along a second direction Y. The first direction X and the second direction Y are both horizontal and perpendicular to each other. A receiving space 22 is formed between the two extrusion rollers 21. The receiving space 22 is used to receive a battery cell 1. The drive assembly 3 cooperates with the extrusion assembly 2 and includes an extrusion drive component 31 and a lifting drive component 32. The extrusion drive component 31 drives the two extrusion rollers 21 to move closer or further apart along the second direction Y. The lifting drive component 32 drives the extrusion rollers 21 to reciprocate in the vertical direction.

[0068] The extrusion roller 21 is a device that applies pressure to the casing 11 of the battery cell 1. The axis S of the extrusion roller 21 extends along the first direction X. There are two extrusion rollers 21, spaced apart along the second direction Y. A receiving space 22 is formed between the two extrusion rollers 21. This receiving space 22 can accommodate battery cells 1 of different thicknesses. The extrusion drive component 31 drives the two extrusion rollers 21 to advance and retract along the second direction Y, that is, drives the two extrusion rollers 21 to move closer or further apart along the second direction Y. Specifically, the two extrusion rollers 21 move closer to each other to reduce the distance between the two extrusion rollers 21, thereby extruding pressure on the casing 11; the two extrusion rollers 21 move further apart to increase the distance between the two extrusion rollers 21, thereby causing the two extrusion rollers 21 to disengage from the casing 11. The lifting drive component 32 drives the extrusion rollers 21 to reciprocate vertically. Specifically, the two extrusion rollers 21 initially approach each other at the bottom of the battery cell 1, applying pressure to the casing 11. Then, the lifting drive component 32 drives the two extrusion rollers 21 vertically upwards, causing the casing 11 to deform and extrude the electrolyte, forcing it to flow directionally from bottom to top. When the two extrusion rollers 21 reach the top of the battery cell 1, the extrusion drive component 31 drives them to move away from each other along the second direction Y, disengaging them from the casing 11. Subsequently, the lifting drive component 32 drives the two extrusion rollers 21 vertically downwards back to the bottom starting position, completing one cycle. During this process, the high-concentration electrolyte at the bottom is forced to the upper middle part of the electrode assembly 12, while the low-concentration electrolyte in the upper middle part is squeezed out from the upper edge, resulting in a more uniform electrolyte concentration and improved electrolyte distribution uniformity within the electrode assembly 12.

[0069] Therefore, the extrusion roller 21 of the extrusion fixture 100 can apply pressure to the large surfaces on both sides of the housing 11. The extrusion roller 21 is driven by the lifting drive component 32 to reciprocate in the vertical direction, thereby realizing the periodic extrusion of the battery cell 1 from bottom to top, thus continuously pushing the electrolyte at the bottom position upward, causing the electrolyte to form convection in the electrode assembly 12. Thus, during the static wetting process, the uniformity of electrolyte distribution in the electrode assembly 12 can be improved, the wetting process can be accelerated, and the electrolyte can be promoted to wet the center position of the electrode assembly 12. During the formation process, not only can the uniformity of electrolyte distribution in the electrode assembly 12 be improved, but also the air bubbles in the battery cell 1 can be fully discharged by extrusion, thereby reducing problems such as local current density imbalance and uneven SEI film growth, and improving the cycle stability and service life of the battery cell 1. Relevant data show that the mixing time of additives in the electrolyte is more than 100 days through concentration diffusion alone. However, by using the extrusion tool 100 to continuously push the electrolyte at the bottom position upward, the electrolyte is encouraged to form convection in the electrode assembly 12, which can greatly shorten the electrolyte distribution time and thus improve the manufacturing efficiency of the battery cell 1.

[0070] It is worth noting that the extrusion tool 100 can be used at any stage of the entire process of segmented liquid injection of battery cells. For example, it can be used in one stage (such as wetting or formation) or in multiple stages (such as wetting and formation).

[0071] The shape of the extrusion roller 21 is not limited. For example, the outer peripheral surface of the extrusion roller 21 is the extrusion surface 213. The axis S of the extrusion roller 21 extends along the first direction X. The extrusion surface 213 extending along the first direction X can be an arc-shaped surface or a cylindrical surface, etc. The material of the extrusion roller 21 is not limited. For example, the extrusion roller 21 can be an elastic material, such as rubber or silicone. When the extrusion roller 21 contacts the housing 11, it can form a surface contact extrusion. Of course, it is not limited to this. The extrusion roller 21 can also be a non-elastic material. When the extrusion roller 21 contacts the housing 11, it can form a line contact extrusion. In the reciprocating motion, the extrusion roller 21 can roll and extrude along the surface of the housing 11 or slide and extrude along the surface of the housing 11. When the extrusion roller 21 rolls and extrudes along the surface of the housing 11, it can be driven passively by friction or driven actively by a motor.

[0072] The form of the drive assembly 3 is not limited. For example, a stepper motor with a lead screw or synchronous belt drive structure can be used to drive the movement of the extrusion roller 21. Alternatively, a pneumatic or hydraulic driver can be used with a push rod to directly drive the extrusion roller 21 to move up and down in the vertical direction and translate in the second direction Y to achieve mutual approach and mutual distance. Of course, it is not limited to this. A limiting device 35 can also be used to make the extrusion roller 21 reciprocate within the upper and lower limit points. The upper limit point can be set near the top of the battery cell 1, and the lower limit point corresponds to the bottom starting position. This makes the movement trajectory and stroke of the extrusion roller 21 more precise, and the extrusion force of the extrusion roller 21 on the housing 11 more uniform and controllable.

[0073] For example, the extrusion fixture 100 is configured such that the extrusion roller 21 applies an extrusion force of 0.1 MPa to 0.6 MPa to the battery cell 1. That is, the configuration and material of the extrusion roller 21, as well as the configuration of the drive assembly 3, allow the extrusion roller 21 to apply an extrusion force of 0.1 MPa to 0.6 MPa to the battery cell 1. For example, the extrusion force can be 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, or 0.6 MPa, etc. Therefore, by extruding the battery cell 1, the uniformity of electrolyte distribution within the casing 11 can be improved more effectively and reliably.

[0074] For example, the compression roller 21 compresses the battery cell 1 at a frequency of 0.5 times / minute to 5 times / minute. That is, the drive assembly 3 is configured such that the compression roller 21 compresses the battery cell 1 at a frequency of 0.5 times / minute to 5 times / minute, meaning that the battery cell 1 can be compressed from bottom to top 0.5 times per minute. For example, the compression frequency can be 0.5 times / minute, 1 time / minute, 2 times / minute, 3 times / minute, 4 times / minute, 5 times / minute, etc. Therefore, by compressing the battery cell 1, the uniformity of electrolyte distribution within the casing 11 can be improved more effectively and reliably.

[0075] In the above technical solution, the extrusion roller 21 of the extrusion fixture 100 performs an extrusion operation on the battery cell 1 from bottom to top in the vertical direction. This effectively pushes the high-concentration electrolyte at the bottom of the electrode assembly 12 upward, thereby forming convection in the electrode assembly 12, improving the distribution of the electrolyte in the electrode assembly 12, and solving the problem of lithium deposition caused by excessively high electrolyte concentration at the edge due to uneven electrolyte distribution. This improves the performance stability and service life of the battery cell 1. At the same time, the extrusion action also causes the bubbles generated during the formation process to be discharged upward, reducing the possibility of local current density imbalance and uneven SEI film growth, improving the cycle stability and service life of the battery cell 1, and also improving the manufacturing efficiency of the battery cell 1.

[0076] refer to Figure 2 and Figure 3 , Figure 3 This is a schematic diagram of an extrusion roller provided in some embodiments of this application. In some embodiments, the outer peripheral surface of the extrusion roller 21 includes an extrusion surface 213. The extrusion surface 213 is a surface of revolution, and the outer contour of the cross-section of the extrusion surface 213 is circular. Along the axial direction of the extrusion roller 21, the radius of the cross-section of the extrusion surface 213 gradually increases from both ends to the middle. For example, the two ends of the extrusion surface 213 in the axial direction are the ends 2131, and the center of the extrusion surface 213 in the axial direction is the middle part 2132. The cross-section of the extrusion surface 213 gradually increases from the ends 2131 to the middle part 2132. Here, the cross-section refers to the cross-sectional shape of the extrusion roller 21 as obtained by a plane perpendicular to the axial direction of the extrusion roller 21. The form in which the cross-section of the extrusion surface 213 gradually increases from the ends 2131 to the middle part 2132 is not limited. For example, the cross-sectional dimension of the extrusion surface 213 from the ends 2131 to the middle part 2132 can gradually increase according to a linear law, or it can gradually increase according to a parabolic curve, etc.

[0077] In the above technical solution, the cross-section of the extrusion surface 213 gradually increases from the end 2131 to the middle 2132, so that during the extrusion process, the extrusion force on the shell 11 in the middle 2132 is relatively stronger, while the extrusion force on the end 2131 is relatively weaker. The deformation trend of the shell 11 also shows that the deformation in the middle is greater and the deformation at both ends is smaller. This makes the arc-shaped contour of the extrusion roller 21 along the second direction Y better fit with the surface of the shell 11, which can reduce the uneven instantaneous migration of electrolyte caused by local pressure concentration, further enhance the global convection of electrolyte, and at the same time reduce the warping or deformation of the edge of the shell 11 during the extrusion process, reduce the bubble retention caused by excessive deformation of the outer edge of the shell 11, improve the uniformity of the overall extrusion effect, and improve the bubble discharge efficiency.

[0078] It is worth noting that the contact length between the extrusion roller 21 and the housing 11 in the first direction X can be less than the length of the housing 11 in the first direction X. In this way, the two sides of the housing 11 in the first direction X can be free from the extrusion roller 21. For example, the ratio of the contact length between the extrusion roller 21 and the housing 11 in the first direction X to the length of the housing 11 in the first direction X can be 3:4. This ensures that the central region of the electrode assembly 12 is sufficiently extruded, so that the high-concentration electrolyte can fully wet the central region and improve the distribution of the electrolyte in the electrode assembly 12. It also reduces the risk of air bubbles being trapped at the edges of the housing 11 due to excessive extrusion deformation.

[0079] refer to Figure 3In some embodiments, the outer peripheral surface of the extrusion roller 21 is an extrusion surface 213, and the extrusion surface 213 of the extrusion roller 21 is configured as an elastic surface. The material of the extrusion surface 213 is not limited. For example, the material of the extrusion surface 213 can be an elastic material such as rubber, silicone, or polyurethane.

[0080] In the above technical solution, the extrusion surface 213 is configured as an elastic surface, so that the extrusion surface 213 of the extrusion roller 21 can form a surface contact extrusion with the surface of the housing 11, which can improve the uniformity of the contact area and pressure distribution. The elastic surface undergoes adaptive deformation under pressure, conforming to the slight unevenness of the surface of the housing 11, reducing mechanical damage (such as active material shedding, diaphragm puncture, etc.) caused by extrusion to the positive electrode, negative electrode, and diaphragm. The rebound characteristics of the elastic surface generate a reverse thrust during extrusion rebound, causing the housing 11 to return to its original deformation. This "extrusion-rebound" cycle drives the electrolyte to penetrate into the poorly conductive areas such as "dead pores" and "narrow pores" of the active material layer, which can reduce local electrolyte retention or voids, so that the active material layer is uniformly covered with electrolyte during the formation stage, improving the distribution of electrolyte in the electrode assembly 12. At the same time, it also significantly enhances the driving force for bubble detachment from the interface, so that the retained bubbles migrate quickly to the exhaust channel with the convection electrolyte, significantly improving the bubble discharge efficiency and realizing bubble detachment.

[0081] refer to Figure 4 and Figure 5 , Figure 4 This is a cross-sectional view of the extrusion roller provided in some embodiments of this application. Figure 5 for Figure 4 The schematic cross-sectional view of the extrusion roller shown shows that, in some embodiments, the extrusion roller 21 includes a rigid portion 211 and an elastic portion 212, with the elastic portion 212 sleeved outside the rigid portion 211, and the elastic portion 212 defining the extrusion surface 213 of the extrusion roller 21.

[0082] In the above technical solution, the extrusion roller 21 includes a rigid part 211 and an elastic part 212. The elastic part 212 is sleeved outside the rigid part 211. The rigid part 211 can provide structural support for the elastic part 212 and connect it with external components, so that the extrusion roller 21 can withstand greater pressure during the extrusion process without excessive deformation or damage, and is easy to process and manufacture. The elastic part 212 surrounds the rigid part 211 and forms an extrusion surface 213, so that the extrusion surface 213 has elastic properties, so that the extrusion roller 21 can better fit the surface of the housing 11 of the battery cell 1 during extrusion, improve the extrusion effect on the housing 11, thereby promoting the convection of electrolyte and improving the uniformity of electrolyte distribution in the electrode assembly 12.

[0083] refer to Figure 4 and Figure 5In some embodiments, the outer contour of the cross-section of the extrusion roller 21 is circular, the outer contour of the cross-section of the rigid part 211 is non-circular, and the inner circumferential surface shape of the elastic part 212 matches the outer circumferential surface shape of the rigid part 211. The outer contour of the cross-section of the rigid part 211 is non-circular; for example, it can be polygonal, elliptical, or oblong, etc. That is, the elastic part 212 and the rigid part 211 are fitted together. Fitting together means that the elastic part 212 is fitted around the outer contour of the rigid part 211, and the inner contour of the cross-section of the elastic part 212 matches the outer contour of the cross-section of the rigid part 211, thereby allowing the rigid part 211 and the elastic part 212 to fit and be fixed better.

[0084] In the above technical solution, the non-circular outer contour of the cross-section of the rigid part 211 increases the connection stability between the rigid part 211 and the elastic part 212, so that the rigid part 211 and the elastic part 212 of the extrusion roller 21 maintain a tight fit during the extrusion process, and will not rotate relative to each other due to shape mismatch, thereby improving the reliability of the extrusion process.

[0085] Of course, it is not limited to this. The outer contour of the cross section of the rigid part 211 can also be circular or the like, in order to provide stable support and facilitate processing.

[0086] refer to Figure 4 and Figure 5 In some embodiments, the elastic part 212 is of uniform wall thickness, that is, the wall thickness of the elastic part 212 is exactly the same everywhere, and there is no situation where the wall thickness gradually changes or the thickness is uneven in some places.

[0087] In the above technical solution, the elastic part 212 and the rigid part 211 are fitted together. The elastic part 212 has a uniform wall thickness. During the extrusion process, the uniform wall thickness makes the deformation degree of each part of the elastic part 212 relatively consistent when it is subjected to the reaction force of the shell 11 while extruding the shell 11. That is, the extrusion pressure is relatively uniform, thereby reducing problems such as local damage to the shell 11 caused by uneven extrusion pressure, reducing the retention of air bubbles caused by excessive deformation of the shell 11, improving the uniformity of the overall extrusion effect, and improving the efficiency of air bubble discharge.

[0088] refer to Figure 2 In some embodiments, the two extrusion rollers 21 have the same structure and are arranged symmetrically about the center axis of the battery cell 1. The same structure means that the overall shape, size, material and composition of the extrusion rollers 21 are exactly the same, and the symmetrical arrangement means that the two extrusion rollers 21 are arranged symmetrically about the center axis of the battery cell 1.

[0089] In the above technical solution, two identical and axially symmetrically arranged extrusion rollers 21 are positioned on both sides of the casing 11 of the extruded battery cell 1, thereby providing mutual reaction forces, simplifying the tooling, and ensuring that the casing 11 is subjected to symmetrical and uniform extrusion forces on both sides. This prevents the casing 11 from undergoing damaging deformation due to pressure differences on both sides during the extrusion process, and improves the stability and extrusion effect of the extrusion force, promotes electrolyte convection, and enhances the uniformity of electrolyte distribution in the electrode assembly 12. Since the two extrusion rollers 21 have the same structure, production efficiency can be improved, manufacturing costs can be reduced, and the maintenance and upkeep of the extrusion tooling 100 can be facilitated.

[0090] refer to Figure 2 In some embodiments, the drive assembly 3 further includes a vibration drive component 33, which drives the extrusion roller 21 to vibrate along the second direction Y. The vibration drive component 33 refers to a device capable of generating vibration and transmitting the vibration to the extrusion roller 21, causing the extrusion roller 21 to vibrate. The form of the vibration drive component 33 is not limited. For example, it may be a vibration motor, an electromagnetic vibrator, a hydraulic vibrator, etc.

[0091] During the formation process, a small amount of electrolyte and lithium are consumed. Simultaneously, bubbles are generated and trapped at the interface between the electrode and the separator, and within the pores of the active material layer. This disrupts the interfacial stability between the electrode assembly 12 and the electrolyte, hindering the electrolyte from wetting the central position of the electrode assembly 12. The vibration drive component 33 causes the extrusion roller 21 to vibrate along the second direction Y, enabling the trapped bubbles to quickly migrate to the exhaust channel, significantly improving bubble removal efficiency and achieving rapid and complete bubble detachment. This shortens the mixing time of additives in the electrolyte, rapidly reduces the electrolyte distribution range, and improves production efficiency. Related data shows that, using concentration diffusion alone, the mixing time of additives in the electrolyte exceeds 100 days, while the arc-shaped roller circulating extrusion device combined with vibration drive can compress the mixing time to 1 day.

[0092] refer to Figure 2 In some embodiments, the drive assembly 3 further includes an adjustment component 34, which is used to adjust the distance between the two extrusion rollers 21 along the second direction Y. The driving form of the adjustment component 34 is not limited. For example, it can be an electric push rod, a hydraulic push rod, a pneumatic push rod, etc. The adjustment component 34 can drive the two extrusion rollers 21 to move along the second direction Y to adjust the distance between the two extrusion rollers 21.

[0093] In the above technical solution, the adjusting component 34 can adjust the distance between the two extrusion rollers 21 along the second direction Y to form a receiving space 22 of different sizes to accommodate battery cells 1 of different thicknesses, thereby improving the adaptability of the extrusion fixture 100 to battery cells 1 of multiple specifications.

[0094] refer to Figure 2In some embodiments, the drive assembly 3 further includes a limiting device 35, which limits the lifting and lowering limits of the extrusion roller 21. The form of the limiting device 35 is not limited. For example, it can be a mechanical stop, such as a stop block that contacts the rotating support 36 or the extrusion roller 21 to prevent movement. Alternatively, the limiting device 35 can be a sensor electrically connected to the lifting drive component 32, controlling its lifting and lowering via a trigger signal. Alternatively, the limiting device 35 can be omitted, and the lifting and lowering limits of the extrusion roller 21 can be directly controlled by programming the lifting stroke of the lifting drive component 32.

[0095] The limiting device 35 restricts the upper limit position of the extrusion roller 21, so that the extrusion roller 21 will not squeeze the housing 11 corresponding to the tab and tab connection area on the upper part of the battery cell 1, thereby reducing the deformation or damage of the tab under pressure and ensuring the conductivity stability and reliability of the battery cell 1.

[0096] In the above technical solution, by setting a limiting device 35 to limit the lifting limit position of the extrusion roller 21, the stroke of the extrusion roller 21 extruding the housing 11 can be limited, thereby making the extrusion force concentrated on the housing 11 area corresponding to the active material layer of the electrode, avoiding ineffective extrusion on the housing 11 area corresponding to the tab and the tab connection area, so that the extrusion is applied to the key area of ​​electrolyte distribution and the extrusion efficiency is improved.

[0097] refer to Figure 2 In some embodiments, the drive assembly 3 includes a rotation support 36, with each end of the extrusion roller 21 having a rotation support 36 at both axial ends, and the two ends of the extrusion roller 21 being rotatably disposed on the rotation supports 36 on both sides. The rotation support 36 is a component used to support the extrusion roller 21 so that it can rotate. Thus, the extrusion roller 21 can be passively driven to rotate by the frictional force between the extrusion roller 21 and the housing 11, thereby rolling along the surface of the housing 11 to extrude force on the housing 11.

[0098] For example, such as Figure 2 As shown, the rotating support 36 may include a support base 361 and a bearing 362. The bearing 362 is connected to the support base 361 and is sleeved on the rotating shafts at both ends of the extrusion roller 21, so that the extrusion roller 21 can rotate relative to the support base 361 through the bearing 362.

[0099] In the above technical solution, the drive assembly 3 includes a rotation support 36, which enables the extrusion roller 21 to rotate through the friction between the extrusion roller 21 and the housing 11, thereby eliminating the need to set up a drive component to drive the extrusion roller 21 to rotate, thus simplifying the tooling, reducing energy consumption, and reducing wear between the extrusion surface 213 of the extrusion roller 21 and the housing 11; at the same time, the rotation support 36 at both ends of the axial direction of the extrusion roller 21 also makes the extrusion roller 21 stable during rotation, which can reduce swaying and deviation.

[0100] refer to Figure 2 In some embodiments, the lifting drive component 32 includes a lifting unit 321 that drives each rotating support 36 to move up and down, and the compression drive component 31 drives the rotating support 36 to move relative to the lifting unit 321 in a second direction Y.

[0101] In the above technical solution, the extrusion drive component 31 drives the rotating support 36 to move relative to the lifting unit 321 along the second direction Y, which can more directly control the motion parameters of the extrusion roller 21, such as the stroke and speed, thereby making it easier to control the extrusion pressure of the extrusion roller 21 on the housing 11 and improving the extrusion effect. Moreover, the extrusion drive component 31 does not need to drive the lifting unit 321 to move, which can reduce the driving energy consumption.

[0102] Of course, this application is not limited to this. For example, the extrusion drive component 31 can also be configured to drive the lifting unit 321 to move along the second direction Y, thereby causing the rotating support 36 and the extrusion roller 21 to move together along the second direction Y. Thus, the overall structure is simple and easy to implement. The two axial ends of the extrusion roller 21 are rotatably mounted on the rotating supports 36 on both sides, so that the extrusion roller 21 is subjected to uniform force during movement, reducing vibration and offset caused by uneven force, and ensuring the stability and reliability of the extrusion process.

[0103] refer to Figure 2 In some embodiments, when the drive assembly 3 further includes the aforementioned adjustment component 34, the adjustment component 34 can be configured to drive the lifting unit 321 to move along the second direction Y, thereby causing the rotating support 36 and the extrusion roller 21 to move together along the second direction Y, thus adjusting the distance between the two extrusion rollers 21 along the second direction Y. Therefore, the overall structure is simple, easy to implement, and has a wide adjustable size range, making it suitable for processing more types of battery cells 1. Of course, this application is not limited to this; alternatively, the adjustment component 34 can also be configured to drive the rotating support 36 to move relative to the lifting unit 321 along the second direction Y, etc.

[0104] The driving form of the lifting unit 321 and the extrusion driving component 31 is not limited. For example, they can both be at least one of electric push rod, hydraulic push rod, and pneumatic push rod.

[0105] For example, the adjusting component 34 and the extrusion driving component 31 can be two separate components and are provided separately. Alternatively, for example, the adjusting component 34 and the extrusion driving component 31 can also be integrated into a single component.

[0106] refer to Figure 2 In some embodiments, when the drive assembly 3 further includes the aforementioned vibration drive component 33, the drive assembly 3 may include a fixed base 39 and a sliding base 38. The vibration drive component 33 drives the sliding base 38 to vibrate relative to the fixed base 39 along the second direction Y. The lifting unit 321 is disposed on the sliding base 38. Thus, by driving the extrusion roller 21 to vibrate relative to the rotating support 36 along the second direction Y through the vibration drive component 33, the trapped bubbles can be quickly migrated to the exhaust channel, significantly improving the bubble discharge efficiency and achieving rapid and complete detachment of the bubbles. Furthermore, the bearing 362 of the rotating support 36 can provide stable support for the extrusion roller 21, reducing the impact of vibration on the rotation of the extrusion roller 21.

[0107] Of course, this application is not limited to this. For example, the vibration driving component 33 can also be disposed between the lifting unit 321 and the rotating support 36 to drive the rotating support 36 to vibrate relative to the lifting unit 321 in the second direction Y.

[0108] refer to Figure 6 , Figure 6 This is a top view showing the usage state of the extrusion fixture provided in some embodiments of this application. In some embodiments, the extrusion fixture 100 is used to extrude a battery cell 1, which includes a housing 11 and an electrode assembly 12 disposed within the housing 11. The electrode assembly 12 includes stacked positive and negative electrode sheets and a separator. The stacking thickness direction of the electrode assembly 12 is consistent with the second direction Y. It should be noted that, due to the stacking thickness direction of the electrode assembly 12, the electrode assembly 12 is either a flattened winding form or a stacked form. In the flattened winding form, the direction in which the electrode assembly 12 is flattened is the stacking thickness direction, and in the stacked form, the stacking direction of the electrode sheets is the stacking thickness direction.

[0109] During the formation process, bubbles are easily generated and retained at the interface between the electrode and the separator and in the pores of the active material layer. In the above technical solution, the extrusion roller 21 of the extrusion tool 100 can apply pressure to the large surfaces on both sides of the housing 11. The extrusion roller 21 is driven by the lifting drive component 32 to reciprocate in the vertical direction, thereby realizing the periodic extrusion of the housing 11 of the electrode assembly 12 from bottom to top, thereby continuously pushing the electrolyte at the bottom position upward, promoting the formation of convection of the electrolyte in the electrode assembly 12, thereby promoting the uniform distribution of the electrolyte in the electrode assembly 12 during the formation process. It can also fully expel the bubbles in the battery cell 1 through extrusion, thereby reducing problems such as local current density imbalance and uneven SEI film growth, and improving the cycle stability and service life of the battery cell 1.

[0110] refer to Figure 7 , Figure 7 The diagram illustrates the usage state of the extrusion suction system provided in some embodiments of this application. In a second aspect, embodiments of this application also provide an extrusion suction system 1000, including a suction fixture 200 and the aforementioned extrusion fixture 100. The suction fixture 200 is used to extract air from the battery cell 1.

[0111] For example, the suction device 200 may consist of a suction port, a suction pipe, and a vacuum pump, etc. The suction port is connected to the suction port of the battery cell 1, and the suction pipe connects the suction port to the vacuum pump, providing a channel for gas flow. The vacuum pump extracts the gas inside the battery cell 1 by generating negative pressure. For example, the suction port may be located at the top of the battery cell 1. The suction device 200 works in conjunction with the extrusion device 100. When the extrusion roller 21 is working and reciprocating in the vertical direction, the top negative pressure suction device continuously extracts air, thereby accelerating the expulsion of bubbles.

[0112] The extrusion and degassing system 1000 according to the embodiments of this application includes a degassing fixture 200 and the extrusion fixture 100 described above. The degassing fixture 200 is used to degas the battery cell 1. It can effectively coordinate the extrusion and degassing actions, accelerate the bubble discharge rate, reduce the possibility of problems such as local current density imbalance and uneven SEI film growth, and improve the cycle stability and service life of the battery cell 1.

[0113] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0114] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. An extrusion tooling, characterized in that, include: An extrusion assembly includes an extrusion roller, the axis of which extends along a first direction. There are two extrusion rollers spaced apart along a second direction. The first direction and the second direction are both horizontal and perpendicular to each other. A receiving space is formed between the two extrusion rollers for accommodating a single battery cell. The drive assembly cooperates with the extrusion assembly and includes an extrusion drive component and a lifting drive component. The extrusion drive component drives the two extrusion rollers to move closer or further apart from each other along the second direction, and the lifting drive component drives the extrusion rollers to reciprocate in the vertical direction.

2. The extrusion fixture according to claim 1, characterized in that, The outer circumferential surface of the extrusion roller includes an extrusion surface, which is a rotating surface. The outer contour of the cross-section of the extrusion surface is circular, and along the axial direction of the extrusion roller, the radius of the cross-section of the extrusion surface gradually increases from both ends to the middle.

3. The extrusion fixture according to claim 1, characterized in that, The outer peripheral surface of the extrusion roller includes an extrusion surface, which is configured as an elastic surface.

4. The extrusion fixture according to claim 3, characterized in that, The extrusion roller includes a rigid part and an elastic part, the elastic part being sleeved outside the rigid part, and the elastic part defining the extrusion surface of the extrusion roller.

5. The extrusion fixture according to claim 4, characterized in that, The outer contour of the cross-section of the extrusion roller is circular, the outer contour of the cross-section of the rigid part is non-circular, and the inner circumferential surface shape of the elastic part matches the outer circumferential surface shape of the rigid part.

6. The extrusion fixture according to claim 4, characterized in that, The elastic part has a uniform wall thickness.

7. The extrusion fixture according to claim 1, characterized in that, The two extrusion rollers have the same structure and are arranged symmetrically.

8. The extrusion fixture according to claim 1, characterized in that, The extrusion fixture is configured such that the extrusion rollers apply an extrusion force of 0.1 MPa to 0.6 MPa to the battery cell.

9. The extrusion fixture according to claim 1, characterized in that, The drive assembly includes a rotation support, and each of the extrusion rollers is provided with a rotation support at both ends of its axial direction. The two ends of the extrusion rollers are rotatably provided on the rotation supports on both sides.

10. The extrusion fixture according to claim 9, characterized in that, The lifting drive component includes a lifting unit that drives each of the rotating supports to move up and down, and the compression drive component drives the rotating support to move relative to the lifting unit in the second direction.

11. The extrusion fixture according to claim 9, characterized in that, The drive assembly further includes an adjustment component for adjusting the spacing between the two extrusion rollers along the second direction; The lifting drive component includes a lifting unit that drives each of the rotating supports to lift, and the adjusting component drives the lifting unit to move along the second direction.

12. The extrusion fixture according to claim 1, characterized in that, The drive assembly also includes a limiting device for limiting the lifting limit position of the extrusion roller.

13. The extrusion fixture according to claim 1, characterized in that, The drive assembly further includes a vibration drive component that drives the extrusion roller to vibrate along the second direction.

14. The extrusion fixture according to claim 1, characterized in that, The extrusion fixture is used to extrude a battery cell, which includes a housing and an electrode assembly disposed within the housing. The electrode assembly includes stacked positive and negative electrode sheets and a separator, and the stacking thickness direction of the electrode assembly is consistent with the second direction.

15. A compression suction system, characterized in that, include: The extrusion fixture and the vacuuming fixture according to any one of claims 1-14, wherein the vacuuming fixture is used to extract air from the battery cell.

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