Longitudinal pulling device for lithium battery diaphragm production

Abstract

The application relates to the technical field of lithium battery diaphragm production, in particular to a lithium battery diaphragm production longitudinal pulling device, which comprises a longitudinal pulling device, a preheating roller and an anti-deviation assembly, the preheating roller and the anti-deviation assembly are arranged in the longitudinal pulling device; the preheating roller is used for preheating lithium battery diaphragm sheets; the anti-deviation assembly is arranged below the preheating roller and is used for limiting the two sides of the lithium battery diaphragm sheets. The application can limit the occurrence of the slipping and deviation phenomenon of the lithium battery diaphragm sheets caused by too much white oil during the longitudinal pulling of the lithium battery diaphragm, so that the lithium battery diaphragm production line can quickly pass through the longitudinal pulling.

Description

Technical Field

[0001] This application relates to the field of lithium battery separator production technology, and in particular to a longitudinal stretching device for lithium battery separator production. Background Technology

[0002] The separator plays a crucial role in lithium-ion batteries, isolating the positive and negative electrodes and preventing short circuits. With the increase in battery energy density and the increasing complexity of battery structures, the mechanical strength requirements for the separator also rise. Higher strength ensures that the separator is less susceptible to damage during battery assembly and use, thereby reducing the risk of short circuits. Secondly, power battery packs are typically composed of multiple individual cells connected in series or parallel to meet the capacity and power requirements of automobiles. This design places higher demands on the mechanical properties of the battery separator. The separator needs to possess good tensile strength and puncture resistance to withstand the various mechanical stresses generated during charging and discharging of the battery pack, ensuring the overall safety and stability of the battery pack.

[0003] To improve diaphragm strength, ultra-high molecular weight polyethylene (UHMWPE) materials are typically used, with a viscosity-average molecular weight of 400,000 to 2,000,000. However, as the relative molecular mass of polyethylene raw materials increases, the processing difficulty of the extruder also increases. To ensure proper melt extrusion of polyethylene in the extruder, the proportion of polyethylene raw materials needs to be reduced. For a 400,000 molecular weight powder, the ratio of powder to white oil might be 30:70, while for a 2,000,000 molecular weight powder, the ratio might be reduced to 16:84. However, an increased white oil content makes slippage more likely on the preheating rollers in the longitudinal stretching process. Although the preheating rollers are equipped with a pressure roller to hold the sheet in place and prevent deviation, in actual production, it has been found that even when the powder content is reduced to below 20%, the pressure roller cannot completely solve the sheet deviation problem, and adjusting to the appropriate pressure range takes a long time, extending the turnaround time of the diaphragm production line. Utility Model Content

[0004] To overcome the above-mentioned defects, this application provides a longitudinal stretching device for lithium battery separator production, including a longitudinal stretching device, a preheating roller, and an anti-deviation component. The preheating roller and the anti-deviation component are both disposed within the longitudinal stretching device. The preheating roller is used to preheat the lithium battery separator sheet, and the anti-deviation component is disposed below the preheating roller to limit the two sides of the lithium battery separator sheet.

[0005] Furthermore, the anti-deviation component includes a metal rod and a limiting block, with the limiting block disposed on the metal rod; the metal rod is used to drive the limiting block to move axially along the preheating roller, and the limiting block is used to limit the two sides of the lithium battery separator sheet.

[0006] Furthermore, the metal rod is a threaded rod, and the limiting block is threadedly connected to the metal rod; the metal rod is used to drive the limiting block to move axially along the preheating roller by rotation.

[0007] Furthermore, there are two limiting blocks, and the two limiting blocks move in opposite directions.

[0008] Furthermore, the anti-deviation component also includes a rocker arm connected to the metal rod for driving the metal rod to rotate, thereby causing the limiting block to move axially along the preheating roller.

[0009] Furthermore, the anti-deviation component also includes a base, which is disposed on the side of the longitudinal tensioning device; the rocker arm is disposed on the base.

[0010] Furthermore, the side of the limiting block facing the preheating roller is an arc surface with a diameter 0.5mm-1mm larger than the roller diameter, while the other sides are flat.

[0011] Furthermore, the limiting block is made of polyimide.

[0012] The above-mentioned technical solution of this application has the following advantages:

[0013] The lithium battery separator production longitudinal stretching device provided in this application includes a longitudinal stretching device, a preheating roller, and an anti-deviation component. Both the preheating roller and the anti-deviation component are installed inside the longitudinal stretching device. The preheating roller is used to preheat the lithium battery separator sheet, and the anti-deviation component is installed below the preheating roller to limit the two sides of the lithium battery separator sheet. This can limit the occurrence of slippage and deviation of the lithium battery separator sheet due to excessive white oil during longitudinal stretching, so that the lithium battery separator production line can quickly pass through the longitudinal stretching process. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0015] Figure 1 A schematic diagram of the longitudinal stretching apparatus for lithium battery separator production provided in this application;

[0016] Figure 2 A schematic diagram of a longitudinal stretching production line for lithium battery separators provided in this application;

[0017] Figure 3 A schematic diagram of the preheating roller provided in this application.

[0018] Reference numerals: 1. Longitudinal tensioning device; 2. Preheating roller; 3. Anti-deviation component; 31. Metal rod; 32. Limiting block; 33. Rocker arm; 34. Base; 4. Lithium battery separator sheet. Detailed Implementation

[0019] The specific embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this application, but are not intended to limit the scope of this application.

[0020] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0022] References to "one embodiment" or "some embodiments" in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized.

[0023] To address the issue of lithium battery separator sheet slippage and misalignment caused by excessive white oil during longitudinal stretching, this application provides a longitudinal stretching device for lithium battery separator production, which eliminates concerns about sheet misalignment during production line operation.

[0024] The specific embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this application, but are not intended to limit the scope of this application.

[0025] like Figure 1 As shown in the figure, this application provides a longitudinal stretching device for lithium battery separator production, including a longitudinal stretching device 1, a preheating roller 2, and an anti-deviation component 3. The preheating roller 2 and the anti-deviation component 3 are both disposed in the longitudinal stretching device 1. The preheating roller 2 is used to preheat the lithium battery separator sheet 4, and the anti-deviation component 3 is disposed below the preheating roller 2 to limit the two sides of the lithium battery separator sheet 4.

[0026] In some embodiments, the anti-deviation component 3 includes a metal rod 31 and a limiting block 32, the limiting block 32 being disposed on the metal rod 31; the metal rod 31 is used to drive the limiting block 32 to move axially along the preheating roller 2, and the limiting block 32 is used to limit the two sides of the lithium battery separator sheet 4.

[0027] In some embodiments, the metal rod 31 is a threaded rod, and the limiting block 32 is threadedly connected to the metal rod 31; the metal rod 31 is used to drive the limiting block 32 to move axially along the preheating roller 2 by rotation.

[0028] In some embodiments, the number of the limiting blocks 32 is two, and the two limiting blocks 32 move in opposite directions.

[0029] In some embodiments, the anti-deviation component 3 further includes a rocker arm 33, which is connected to the metal rod 31 and is used to drive the metal rod 31 to rotate, thereby causing the limiting block 32 to move axially along the preheating roller 2.

[0030] In some embodiments, the anti-deviation component 3 further includes a base 34, which is disposed on the side of the longitudinal tensioning device 1; the rocker arm 33 is disposed on the base 34.

[0031] In some embodiments, the side of the limiting block 32 facing the preheating roller 2 is an arc surface with a diameter 0.5mm-1mm larger than the roller diameter, while the other sides are flat.

[0032] In some embodiments, the limiting block 32 is made of polyimide.

[0033] The longitudinal stretching equipment has a base and a rocker arm mounted on its side. A threaded metal rod is attached to the rocker arm, which connects two limiting blocks. The distance between the two limiting blocks can be controlled by rotating the rocker arm. The limiting blocks facing the preheating roller are curved surfaces that are 0.5mm-1mm larger than the roller diameter (preheating roller diameter 300mm, limiting block diameter 300.5-301mm). All other surfaces are flat. The material used is heat-resistant, chemically resistant, and easily moldable polyimide.

[0034] The main production processes for wet-process lithium-ion battery separators include: 1. Raw material melt extrusion; 2. Cold roll casting; 3. Longitudinal stretching; 4. Primary transverse stretching; 5. Extraction and membrane surface drying; 6. Secondary transverse stretching; 7. Heat setting and winding. Experimental conditions: Using Daehan Oil Chemical VH200U raw material, PE raw material: white oil = 17:83. Figure 2 As shown, the limiting device is installed below L3 / L5 / L7.

[0035] Optimize sheet misalignment (e.g.) Figure 3 As shown, the deviation distance is the difference between the roller edge and the sheet edge (d1-d2). Common conditions mainly include roller temperature (L2 / L3 at the same temperature, L4 / L5 / L6 at the same temperature), speed ratio (adjustment mainly involves L2, L3, and L4), pressure roller pressure (pressure roller pressure settings are consistent), and comparison of setting experiments with using limit devices.

[0036] Experiment 1: Roller temperature: 100℃ / 105℃; Roller speed ratio: 103% / 102% / 101%; Roller pressure: 0.2 MPa; Not used

[0037] Improvement 2: Roller temperature: 90℃ / 95℃; Roller speed ratio: 103% / 102% / 101%; Roller pressure: 0.2Mpa; Not used.

[0038] Improvement 3: Roller temperature: 90℃ / 95℃; Roller speed ratio: 105% / 104% / 103%; Roller pressure: 0.2Mpa; Not used

[0039] Improvement 4: Roller temperature: 90℃ / 95℃; Roller speed ratio: 105% / 104% / 103%; Roller pressure: 0.1Mpa; Not used.

[0040] Improvement 5: Roller temperature: 90℃ / 95℃; Roller speed ratio: 105% / 104% / 103%; Roller pressure: 0.1Mpa; Usage

[0041] Improvement 6: Roll temperature: 100℃ / 105℃; Roll speed ratio: 103% / 102% / 101%; Roll pressure: 0.2Mpa; Usage

[0042]

[0043] In Experiment 1, the sheet deviated significantly during film threading, causing it to shift to one side and preventing threading, resulting in a long delay. By adjusting the roller temperature, roller speed, and roller pressure, we achieved parameters that minimized the deviation distance and shortened the threading time, but this still required a considerable amount of time. After fixing the parameters and using a limiting device, the sheet was essentially centered and threaded through in one go without any waste. Restoring the parameters from Experiment 1 had virtually no impact on the sheet deviation.

[0044] This application adds a limiting device to the longitudinal stretching process of separator production, so that it is not affected or is minimally affected by the process parameters, and forcibly fixes the sheet in the center position. After using the longitudinal stretching device for lithium battery separator production provided by this application, the longitudinally stretched sheet will not deviate under different parameters, and will not affect the subsequent production line connection, greatly saving the connection time of this type of product.

[0045] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application.

[0046] It should be clarified that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. This application is not limited to the specific structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and techniques are omitted here.

[0047] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A lithium battery separator production longitudinal stretching device characterized by, The device includes a longitudinal stretching device, a preheating roller, and an anti-deviation component. Both the preheating roller and the anti-deviation component are located inside the longitudinal stretching device. The preheating roller is used to preheat the lithium battery separator sheet, and the anti-deviation component is located below the preheating roller to limit the movement of both sides of the lithium battery separator sheet.

2. The lithium battery separator production longitudinal stretching device according to claim 1, wherein, The anti-deviation component includes a metal rod and a limiting block, with the limiting block disposed on the metal rod. The metal rod is used to drive the limiting block to move axially along the preheating roller, and the limiting block is used to limit the two sides of the lithium battery separator sheet.

3. The lithium battery separator production longitudinal stretching device according to claim 2, wherein, The metal rod is a threaded rod, and the limiting block is threadedly connected to the metal rod; the metal rod is used to drive the limiting block to move axially along the preheating roller by rotation.

4. The lithium battery separator production longitudinal stretching device according to claim 2, wherein, The number of limiting blocks is two, and the two limiting blocks move in opposite directions.

5. The lithium battery separator production longitudinal stretching apparatus according to claim 2, wherein, The anti-deviation component also includes a rocker arm connected to the metal rod, which drives the metal rod to rotate, thereby causing the limiting block to move axially along the preheating roller.

6. The lithium battery separator production longitudinal stretching apparatus according to claim 5, wherein, The anti-deviation component also includes a base, which is disposed on the side of the longitudinal tensioning device; the rocker arm is disposed on the base.

7. The lithium battery separator production longitudinal stretching apparatus according to claim 2, wherein The side of the limiting block facing the preheating roller is an arc surface with a diameter 0.5mm-1mm larger than the roller diameter, while the other sides are flat.

8. The lithium battery separator production longitudinal stretching apparatus according to claim 2, wherein, The limiting block is made of polyimide.

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