Low-resistance ultra-high molecular weight polyethylene lithium battery diaphragm

Abstract

The utility model relates to the technical field of battery diaphragms, and discloses a low-resistance ultra-high molecular weight polyethylene lithium battery diaphragm which mainly comprises a diaphragm body, the diaphragm body comprises a hot melting layer and a base layer, a plurality of first ion through holes are formed in the hot melting layer, and a plurality of second ion through holes are formed in the base layer. According to the technical scheme, the problem of thermal runaway of the battery caused by the fact that ions are still conveyed to the battery through the diaphragm under the condition that the battery is heated in the prior art is solved.

Description

Technical Field

[0001] This utility model relates to the field of battery separator technology, and in particular to a low-resistance ultra-high molecular weight polyethylene lithium battery separator. Background Technology

[0002] The battery separator is a key component of batteries, especially in secondary batteries such as lithium batteries, where it plays a crucial role. It is typically located between the positive and negative electrodes, and its main function is to prevent direct contact between the two electrodes, which could lead to a short circuit.

[0003] Currently, since the battery separator itself is an electronic insulator, several micropores are usually opened on its surface to ensure that lithium ions (or other charge carriers) can pass through the separator quickly, thereby ensuring the energy transfer efficiency of the battery itself and indirectly reducing the resistance of the battery separator to ion transport (making it have low resistance characteristics).

[0004] However, lithium batteries are prone to overcharging during use due to prolonged charging and capacity decay. This can lead to irreversible chemical changes inside the battery, causing abnormal conditions such as overheating and bulging. If ions are still being supplied to the lithium battery under these circumstances, it can easily lead to thermal runaway and cause dangerous accidents such as fire and explosion. Utility Model Content

[0005] The main purpose of this invention is to provide a low-resistance ultra-high molecular weight polyethylene lithium battery separator, which aims to solve the problem in related technologies where ions can still be transported to the battery through the separator even when the battery is heating up, leading to battery thermal runaway.

[0006] To achieve the above objectives, the technical solution of this utility model is as follows:

[0007] A low-resistance ultra-high molecular weight polyethylene lithium battery separator includes a separator body, the separator body includes a hot-melt layer and a base layer, the hot-melt layer is provided with a plurality of first ion passage holes, and the base layer is provided with a plurality of second ion passage holes.

[0008] Furthermore, the first ion passage holes and the second ion passage holes are staggered, and the projection plane of each second ion passage hole in its axial direction overlaps with the projection plane of each first ion passage hole in its axial direction.

[0009] Furthermore, the aperture of each of the first ion passage holes is the same as the aperture of each of the second ion passage holes, and the area of ​​the overlapping portion is greater than or equal to half the area of ​​the projection surface of the first ion passage hole in its axial direction.

[0010] Furthermore, a hot-melt layer is provided on both sides of the base layer.

[0011] Furthermore, a flow-limiting coating is provided between the base layer and the hot-melt layer.

[0012] Furthermore, the sum of the thicknesses of each of the aforementioned hot-melt layers is greater than or equal to one-half of the total thickness of the diaphragm body.

[0013] The working principle and beneficial effects of this utility model are as follows:

[0014] This utility model mainly includes a hot melt layer and a base layer. The hot melt layer and the base layer are respectively provided with a number of first ion passage holes and a number of second ion passage holes. Each first ion passage hole and each second ion passage hole are interconnected to ensure that ions can pass through this utility model quickly.

[0015] Meanwhile, the hot melt layer is made of PE (polyethylene) material, with a melting point range of approximately 105℃ to 137℃. This means that when the ambient (battery) temperature rises to a dangerous threshold, the hot melt layer will melt, which will not only damage the first ion passage pores in its own structure, but also seal the second ion passage pores located on the base layer, thereby cutting off the ion transport path, cutting off the internal current, and interrupting the exothermic reaction chain inside the battery, thus preventing the battery from experiencing thermal runaway. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model 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 this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of this embodiment;

[0018] Figure 2 for Figure 1 Top view;

[0019] Figure 3 for Figure 1 A sectional view;

[0020] Figure 4 This is an exploded view diagram of this embodiment.

[0021] Explanation of icon numbers:

[0022] 1. Diaphragm body; 11. Hot melt layer; 111. First ion passage hole; 12. Base layer; 121. Second ion passage hole.

[0023] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0025] like Figure 1 As shown, this embodiment proposes a low-resistance ultra-high molecular weight polyethylene lithium battery separator, mainly comprising a separator body 1, which includes a hot-melt layer 11 and a base layer 12. To facilitate the passage of ions through the separator body 1, the hot-melt layer 11 in this embodiment is provided with a plurality of first ion-passing holes 111, and the base layer 12 is provided with a plurality of second ion-passing holes 121. Each first ion-passing hole 111 and each second ion-passing hole 121 are interconnected and correspond one-to-one, forming a channel for ions to quickly pass through the separator body 1, thus ensuring the low resistance of the separator body 1 itself.

[0026] Meanwhile, the hot melt layer 11 is preferably made of hot melt materials such as polyethylene, because the melting point of polyethylene is usually between 105 and 137°C, which is highly matched with the initial trigger temperature of battery thermal runaway. That is, when the battery temperature rises to the melting point of the hot melt layer 11 (the danger threshold of the battery), the hot melt layer 11 will begin to melt. As the hot melt layer 11 melts, it will not only damage the structure of each first ion passage pore 111 located on itself, but also deform due to melting, thereby blocking and sealing each second ion passage pore 121 located on the base layer 12, thereby cutting off the ion transport path, cutting off the internal current, and interrupting the exothermic reaction chain inside the battery, effectively avoiding the occurrence of thermal runaway in the battery.

[0027] like Figures 2-3 As shown, in this embodiment, the first ion passage holes 111 and the second ion passage holes 121 are staggered. The projection plane of each second ion passage hole 121 in its axial direction overlaps with the projection plane of each first ion passage hole 111 in its axial direction. That is, each first ion passage hole 111 and each second ion passage hole 121 are eccentrically arranged in a one-to-one correspondence. In this way, polyethylene (hot melt material) can be directly present in the axial direction of each second ion passage hole 121. When the hot melt material is heated and melted, it can be directly dripped into or flow into the second ion passage hole 121 to seal the second ion passage hole 121, effectively improving the sealing and cutting-off efficiency of each ion passage hole.

[0028] A hot melt layer 11 is provided on both the upper and lower sides of the base layer 12 (the two ends of the second ion passage hole 121 in the axial direction). Even though this embodiment has a double insurance mechanism, it avoids that only a single hot melt layer 11 will not completely close the second ion passage holes 121 on the base layer 12 after melting, thus fully improving the stability and performance of the thermal shutdown response of this embodiment.

[0029] The sum of the thicknesses of each hot-melt layer 11 is greater than or equal to half the total thickness of the diaphragm body 1. That is, when the total thickness of the diaphragm body 1 is 10 μm, the sum of the thicknesses of the two hot-melt layers 11 is greater than or equal to 5 μm. This ensures that after each hot-melt layer 11 melts, it can fully cover and fill each of the second ion passage holes 121 located in the base layer 12, further ensuring the sealing effect of each ion passage hole in this embodiment.

[0030] Furthermore, each hot melt layer 11 is located on both sides of the base layer 12, so that when the temperature changes on both the inner and outer sides of this embodiment, there is a corresponding hot melt layer 11 that can react in time, giving this embodiment the feature of bidirectional thermal shutdown protection.

[0031] Meanwhile, the aperture of each first ion passage hole 111 is the same as the aperture of each second ion passage hole 121, and the area of ​​the overlapping part is greater than or equal to half the area of ​​the projection surface of the first ion passage hole 111 in its axial direction, ensuring that there is enough overlapping part (connection path) between each first ion passage hole 111 and each second ion passage hole 121 to fully guarantee the ion passage efficiency.

[0032] like Figure 4 As shown, in this embodiment, a flow-limiting coating is provided between the base layer 12 and the hot-melt layer 11. The flow-limiting coating is preferably a ceramic coating, that is, ceramic particles (such as nano Al2O3, SiO2) are coated on the surface of the base layer in a porous or dense form, forming a rough microstructure between the base layer 12 and the hot-melt layer 11. In this way, when the hot-melt layer 11 is heated and softened, the protrusions and pores of the ceramic particles will "hook" the PE molecular chains, hindering their overall movement and realizing a physical anchoring effect (similar to the mechanical interlocking principle of Velcro). Combined with the viscosity of the PE material after melting, it can effectively prevent the molten hot-melt layer 11 from flowing and being lost along the surface of the base layer 12, ensuring that the molten hot-melt layer 11 can stably complete the sealing work of each second ion passage hole 121 on the base layer 12.

[0033] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this application, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they 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. Therefore, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0034] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A low-resistance ultra-high molecular weight polyethylene lithium battery separator, comprising a separator body (1), characterized in that, The diaphragm body (1) includes a hot melt layer (11) and a base layer (12). The hot melt layer (11) is provided with a plurality of first ion passage holes (111), and the base layer (12) is provided with a plurality of second ion passage holes (121).

2. The low-resistance ultra-high molecular weight polyethylene lithium battery separator according to claim 1, characterized in that, The first ion passage holes (111) and the second ion passage holes (121) are staggered, and the projection plane of the second ion passage hole (121) in its axial direction overlaps with the projection plane of the first ion passage hole (111) in its axial direction.

3. The low-resistance ultra-high molecular weight polyethylene lithium battery separator according to claim 2, characterized in that, The aperture of each of the first ion passage holes (111) is the same as the aperture of each of the second ion passage holes (121), and the area of ​​the overlapping portion is greater than or equal to half the area of ​​the projection surface of the first ion passage hole (111) in its axial direction.

4. The low-resistance ultra-high molecular weight polyethylene lithium battery separator according to claim 1 or 2, characterized in that, The base layer (12) has a hot melt layer (11) on both sides.

5. The low-resistance ultra-high molecular weight polyethylene lithium battery separator according to claim 1, characterized in that, A flow-limiting coating is provided between the base layer (12) and the hot melt layer (11).

6. The low-resistance ultra-high molecular weight polyethylene lithium battery separator according to claim 4, characterized in that, The sum of the thicknesses of each of the hot melt layers (11) is greater than or equal to half the total thickness of the diaphragm body (1).

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