Lithium battery separator with high temperature resistance

Abstract

The application discloses a lithium battery diaphragm with high-temperature resistance, and relates to the field of battery diaphragms.The lithium battery diaphragm with high-temperature resistance comprises a polyimide base film, a polypropylene layer, a blocking mechanism and a rebound mechanism, the polyimide base film is connected with the polypropylene layer, the polypropylene layer is connected with the blocking mechanism, the blocking mechanism is connected with the rebound mechanism, the rebound mechanism is connected with a ceramic film layer, and the polyimide base film, the polypropylene layer, the blocking mechanism and the rebound mechanism are all provided with micropores, and the ceramic film layer is provided with a blocking mechanism.The lithium battery diaphragm with high-temperature resistance can disperse the heat generated by the lithium battery to the whole diaphragm through the ceramic film layer, when the temperature in the lithium battery reaches the upper limit, the expansion of the expansion capsule blocks the receiving cavity, prevents the electrolyte from reacting with the electrode in an electrochemical manner, prevents the temperature from being too high, and further makes the lithium battery diaphragm with high-temperature resistance.

Description

Technical Field

[0001] This invention relates to the field of battery separator technology, specifically to a lithium battery separator with high temperature resistance. Background Technology

[0002] Lithium-ion batteries use lithium metal or lithium alloy as the anode material and a non-aqueous electrolyte solution. In the structure of a lithium-ion battery, the separator is one of the key internal components. The performance of the separator determines the battery's interface structure, internal resistance, etc., and directly affects the battery's capacity, cycle life, and safety performance. A high-performance separator plays an important role in improving the overall performance of the battery. The main function of the separator is to separate the positive and negative electrodes of the battery to prevent the two electrodes from contacting and short-circuiting. In addition, it also has the function of allowing electrolyte ions to pass through. However, existing lithium-ion battery separators still have certain defects in use, such as...

[0003] Publication number CN109103398A discloses a lithium battery separator, comprising a frame, a membrane body bonded to the inner wall of the frame, and a support rod bonded to the front of the membrane body. The top and bottom of the support rod are fixedly connected to the inner wall of the frame. The membrane body includes a base layer, an anti-corrosion layer, a high-temperature resistant layer, and a ceramic membrane layer. The surface of the base layer is bonded to the anti-corrosion layer, the surface of the anti-corrosion layer is bonded to the high-temperature resistant layer, and the high-temperature resistant layer is bonded to the ceramic membrane layer. By using the frame, support rod, membrane body, base layer, anti-corrosion layer, polyethylene layer, polypropylene layer, high-temperature resistant layer, epoxy resin layer, polyvinylidene fluoride layer, and ceramic membrane layer in combination, the short service life problem of existing lithium battery separators is solved. This lithium battery separator has the advantage of a long service life, improved corrosion resistance and high-temperature resistance, facilitates user use, and improves the practicality of the lithium battery separator.

[0004] The aforementioned document describes how the corrosion resistance and high-temperature resistance of a lithium battery separator are improved through the combined use of a frame, support rod, membrane, base layer, anti-corrosion layer, polyethylene layer, polypropylene layer, high-temperature resistant layer, epoxy resin layer, polyvinylidene fluoride layer, and ceramic membrane layer. However, when a lithium battery malfunctions and the internal temperature continues to rise, this method cannot prevent the temperature from continuing to rise, resulting in poor high-temperature resistance. Therefore, a high-temperature resistant lithium battery separator is proposed to address these issues. Summary of the Invention

[0005] The purpose of this invention is to provide a high-temperature resistant lithium battery separator to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a high-temperature resistant lithium battery separator, comprising: a polyimide-based film, a polypropylene layer, a barrier mechanism, and a springback mechanism;

[0007] A polypropylene layer is connected above the polyimide-based film, a barrier mechanism is connected above the polypropylene layer, a rebound mechanism is connected above the barrier mechanism, and a ceramic film layer is connected above the rebound mechanism. Micropores are formed in the polyimide-based film, the polypropylene layer, the barrier mechanism, and the rebound mechanism. A blocking mechanism is provided in the ceramic film layer.

[0008] The closure mechanism includes: a receiving cavity, a positioning band, an expansion bladder, and an evaporating liquid. The receiving cavity is formed inside the ceramic film layer and is positioned above the micropores.

[0009] Preferably, a positioning band is connected to the inner wall of the storage cavity.

[0010] Preferably, the end of the positioning band away from the storage cavity is connected to an expansion bladder.

[0011] Preferably, the expansion bladder is filled with an evaporating liquid.

[0012] Preferably, the rebound mechanism includes: a rubber grid, a thermoplastic polyurethane film, a U-shaped spring sheet, and an air cavity. The rubber grid is bonded between the barrier mechanism and the ceramic film layer, and the thermoplastic polyurethane film is connected to the inner wall of the rubber grid.

[0013] Preferably, the rubber grid has two sets of spiral springs embedded inside.

[0014] Preferably, an air cavity is provided between the two sets of the spiral springs, and the air cavity is opened within the rubber grid.

[0015] Preferably, the barrier mechanism includes: a polyethylene layer, a slot, a polyvinylidene fluoride coating film, and a triphenyl phosphate flame retardant, wherein a polyethylene layer is bonded between the polypropylene layer and the rubber grid, and a slot is formed in the polyethylene layer.

[0016] Preferably, a polyvinylidene fluoride (PVDF) coating film is attached to the inner wall of the empty slot.

[0017] Preferably, the polyvinylidene fluoride coating is filled with triphenyl phosphate flame retardant.

[0018] Compared with the prior art, the beneficial effects of the present invention are: the high-temperature resistant lithium battery separator disperses the heat generated by the lithium battery to the entire separator through the ceramic film layer. When the temperature inside the lithium battery reaches the upper limit, the expansion bladder expands to block the receiving cavity, preventing the electrolyte from undergoing an electrochemical reaction with the electrode, thus preventing the temperature from getting too high, thereby making the high-temperature resistant lithium battery separator resistant to high temperatures.

[0019] 1. This high-temperature resistant lithium battery separator evenly distributes the heat generated by the lithium battery throughout the separator through the ceramic membrane layer. The boiling point temperature of the evaporator is the same as the upper limit temperature of the lithium battery. When the upper limit temperature is reached inside the lithium battery, the expansion bladder expands rapidly, blocking the storage cavity and preventing the electrolyte from undergoing an electrochemical reaction with the electrode. The polypropylene layer and polyethylene layer are made of materials that can withstand high temperatures. When the temperature is too high, the polyethylene layer melts and closes the pores, and the polyethylene in the polyethylene layer will penetrate into the polypropylene pores of the polypropylene layer. At the same time, the polypropylene layer will also melt and close the pores to prevent the temperature from getting too high, thereby improving the high-temperature resistance of this high-temperature resistant lithium battery separator.

[0020] 2. The high-temperature resistant lithium battery separator uses a resilient spring sheet, rubber grid, and thermoplastic polyurethane film for resilience, which prevents wrinkles from forming when the separator expands thermally, thereby improving the structural strength of the high-temperature resistant lithium battery separator.

[0021] 3. The high-temperature resistant lithium battery separator encapsulates triphenyl phosphate flame retardant through a polyvinylidene fluoride (PVDF) coating. When the lithium battery temperature reaches its ignition point, the PVDF coating melts upon heating, releasing the triphenyl phosphate flame retardant, which inhibits the combustion of the electrolyte and thus improves the flame retardant performance of the high-temperature resistant lithium battery separator. Attached Figure Description

[0022] Figure 1 This is a three-dimensional exploded structural diagram of the present invention;

[0023] Figure 2 This is a three-dimensional structural diagram of the present invention;

[0024] Figure 3 This is a schematic diagram of the three-dimensional cross-sectional structure of the present invention;

[0025] Figure 4 This is a schematic diagram of the three-dimensional cross-sectional structure of the ceramic film layer of the present invention;

[0026] Figure 5 This is a schematic diagram of the three-dimensional cross-sectional structure of the rubber grid of the present invention;

[0027] Figure 6 This is a schematic diagram of the three-dimensional cross-sectional structure of the polyethylene layer of the present invention.

[0028] In the diagram: 1. Polyimide-based film; 2. Polypropylene layer; 3. Barrier mechanism; 301. Polyethylene layer; 302. Empty slot; 303. Polyvinylidene fluoride coating film; 304. Triphenyl phosphate flame retardant; 4. Rebound mechanism; 401. Rubber grid; 402. Thermoplastic polyurethane film; 403. Rebound spring; 404. Air cavity; 5. Ceramic film layer; 6. Micropores; 7. Closure mechanism; 701. Receiving cavity; 702. Positioning band; 703. Expansion bladder; 704. Evaporating liquid. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Please see Figures 1-4 This invention provides a technical solution: a high-temperature resistant lithium battery separator, comprising: a polyimide-based film 1, a polypropylene layer 2, a barrier mechanism 3, and a rebound mechanism 4; the polypropylene layer 2 is connected above the polyimide-based film 1, the barrier mechanism 3 is connected above the polypropylene layer 2, the rebound mechanism 4 is connected above the barrier mechanism 3, and a ceramic film layer 5 is connected above the rebound mechanism 4; all components of the polyimide-based film 1, the polypropylene layer 2, the barrier mechanism 3, and the rebound mechanism 4 are... The ceramic membrane layer 5 has micropores 6 and a sealing mechanism 7 is provided inside it. The sealing mechanism 7 includes a receiving cavity 701, a positioning band 702, an expansion bladder 703 and an evaporating liquid 704. The receiving cavity 701 is provided inside the ceramic membrane layer 5 and is located above the micropores 6. The positioning band 702 is connected to the inner wall of the receiving cavity 701. The end of the positioning band 702 away from the receiving cavity 701 is connected to the expansion bladder 703 and the expansion bladder 703 is filled with the evaporating liquid 704.

[0031] In practical implementation, the ceramic membrane layer 5 evenly disperses the heat generated by the lithium battery, rapidly conducting and dispersing the heat throughout the separator when local overheating occurs. Micropores 6 enhance the liquid-holding capacity of the separator and provide more space for thermal expansion. A positioning band 702 centrally fixes the expansion bladder 703 within the receiving cavity 701. The positioning band 702 can be made of rubber or other corrosion-resistant flexible materials. The expansion bladder 703 can be made of rubber. The boiling point temperature of the evaporator 704 is the same as the upper limit of the safe temperature range for the lithium battery. When the internal temperature of the lithium battery reaches the upper limit, the evaporator within the expansion bladder 703... The rapid vaporization of liquid 704 causes the expansion bladder 703 to expand rapidly, blocking the receiving cavity 701 to prevent the electrolyte from passing through the micropores 6 and to prevent the electrolyte from undergoing an electrochemical reaction with the electrodes. The materials of polypropylene layer 2 and polyethylene layer 301 are heat-resistant. When the temperature is too high, polyethylene layer 301 first melts and closes the pores to break the circuit, protecting the battery. As the temperature continues to rise, the polyethylene in polyethylene layer 301 will seep into the polypropylene pores of polypropylene layer 2, and polypropylene layer 2 will also melt and close the pores, providing a second layer of protection to prevent the temperature from getting too high, thereby improving the high-temperature resistance of the lithium battery separator.

[0032] See Figures 2-3 and Figure 5It is known that the rebound mechanism 4 includes: a rubber grid 401, a thermoplastic polyurethane film 402, a U-shaped spring sheet 403, and an air cavity 404. The rubber grid 401 is pasted between the barrier mechanism 3 and the ceramic film layer 5. The thermoplastic polyurethane film 402 is connected to the inner wall of the rubber grid 401. Two sets of U-shaped spring sheets 403 are embedded inside the rubber grid 401. An air cavity 404 is provided between the two sets of U-shaped spring sheets 403. The air cavity 404 is opened inside the rubber grid 401.

[0033] In practice, the air cavity 404 can conduct heat, and the rubber grid 401, thermoplastic polyurethane film 402 and air cavity 404 can rebound after deformation, preventing the separator from wrinkling or even breaking when it is stretched or thermally expanded, thereby improving the structural strength of the high-temperature resistant lithium battery separator.

[0034] See Figures 1-3 and Figure 6 It is known that the barrier mechanism 3 includes: a polyethylene layer 301, a slot 302, a polyvinylidene fluoride coating film 303, and a triphenyl phosphate flame retardant 304. The polyethylene layer 301 is pasted between the polypropylene layer 2 and the rubber grid 401. A slot 302 is opened in the polyethylene layer 301. The polyvinylidene fluoride coating film 303 is connected to the inner wall of the slot 302. The polyvinylidene fluoride coating film 303 is filled with triphenyl phosphate flame retardant 304.

[0035] In practice, a polyvinylidene fluoride (PVDF) coating film 303 is used to encapsulate the triphenyl phosphate flame retardant 304, preventing the triphenyl phosphate flame retardant 304 from dissolving directly into the electrolyte. When the lithium battery temperature runs out of control and is about to reach the ignition point, the PVDF coating film 303 melts upon heating, releasing the triphenyl phosphate flame retardant 304, which inhibits the combustion of the electrolyte, thereby improving the flame retardant performance of the high-temperature resistant lithium battery separator.

[0036] In summary, when using this high-temperature resistant lithium battery separator, it is installed inside the battery to separate the positive and negative electrodes. The electrolyte wets the entire separator through the micropores 6 and the receiving cavity 701, reacting with the positive and negative electrodes. The polyimide-based membrane 1, micropores 6, polypropylene layer 2, and polyethylene layer 301 are all high-temperature resistant materials. The micropores 6 provide wear resistance and uniform heat conduction, ensuring long-term use of the separator at high temperatures. The expansion bladder 703 and evaporator 704 provide primary protection, while the polypropylene layer 2 and polyethylene layer 301 provide secondary protection. The polyvinylidene fluoride (PVDF) packaging... The coating 303 and triphenyl phosphate flame retardant 304 serve as a third-level protection. When the lithium battery temperature rises, the expansion bladder 703 first blocks the receiving cavity 701 to prevent electrolyte reaction. If the temperature continues to rise, it reaches the melting point of the polypropylene layer 2 and the polyethylene layer 301, blocking the micropores 6 within the polypropylene layer 2 and the polyethylene layer 301. If the temperature still rises, it reaches the melting point of the polyvinylidene fluoride coating 303, releasing the triphenyl phosphate flame retardant 304 to inhibit electrolyte combustion. The contents not described in detail in this specification are prior art known to those skilled in the art.

[0037] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-temperature resistant lithium battery separator, comprising: The polyimide-based film (1), the polypropylene layer (2), the barrier mechanism (3), and the springback mechanism (4) are characterized in that; A polypropylene layer (2) is connected above the polyimide-based film (1), a barrier mechanism (3) is connected above the polypropylene layer (2), a rebound mechanism (4) is connected above the barrier mechanism (3), and a ceramic film layer (5) is connected above the rebound mechanism (4). Micropores (6) are provided in the polyimide-based film (1), the polypropylene layer (2), the barrier mechanism (3), and the rebound mechanism (4). A sealing mechanism (7) is provided in the ceramic film layer (5). The blocking mechanism (7) includes: a receiving cavity (701), a positioning band (702), an expansion bladder (703), and an evaporating liquid (704). The receiving cavity (701) is provided in the ceramic film layer (5), and the receiving cavity (701) is located above the micropore (6). A positioning band (702) is connected to the inner wall of the storage cavity (701); The positioning band (702) is connected to an expansion bladder (703) at the end away from the receiving cavity (701); The expansion bladder (703) is filled with evaporating liquid (704).

2. The high-temperature resistant lithium battery separator according to claim 1, characterized in that: The rebound mechanism (4) includes: a rubber grid (401), a thermoplastic polyurethane film (402), a spring sheet (403), and an air cavity (404). The rubber grid (401) is attached between the barrier mechanism (3) and the ceramic film layer (5), and the thermoplastic polyurethane film (402) is connected to the inner wall of the rubber grid (401).

3. A high-temperature resistant lithium battery separator according to claim 2, characterized in that: The rubber grid (401) is internally fitted with two sets of spiral springs (403).

4. A high-temperature resistant lithium battery separator according to claim 3, characterized in that: An air cavity (404) is provided between the two sets of the spiral springs (403), and the air cavity (404) is opened in the rubber grid (401).

5. A high-temperature resistant lithium battery separator according to claim 1, characterized in that: The barrier mechanism (3) includes: a polyethylene layer (301), a slot (302), a polyvinylidene fluoride coating film (303), and a triphenyl phosphate flame retardant (304). The polyethylene layer (301) is bonded between the polypropylene layer (2) and the rubber grid (401), and the slot (302) is formed in the polyethylene layer (301).

6. A high-temperature resistant lithium battery separator according to claim 5, characterized in that: A polyvinylidene fluoride (PVDF) coating membrane (303) is attached to the inner wall of the empty groove (302).

7. A high-temperature resistant lithium battery separator according to claim 6, characterized in that: The polyvinylidene fluoride coating (303) is filled with triphenyl phosphate flame retardant (304).

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