Lithium battery diaphragm with high temperature resistance

Abstract

The invention discloses a high-temperature-resistant lithium battery diaphragm, which relates to the field of battery diaphragms and comprises a polyimide base membrane, a polypropylene layer, a barrier mechanism and a rebound mechanism, the polypropylene layer is connected to the upper portion of the polyimide base film, the blocking mechanism is connected to the upper portion of the polypropylene layer, the rebound mechanism is connected to the upper portion of the blocking mechanism, the ceramic film layer is connected to the upper portion of the rebound mechanism, and micropores are formed in the polyimide base film, the polypropylene layer, the blocking mechanism and the rebound mechanism. And a blocking mechanism is arranged in the ceramic membrane layer. According to the high-temperature-resistant lithium battery diaphragm, heat generated by a lithium battery is dispersed to the whole diaphragm through the ceramic membrane layer, and when the temperature in the lithium battery reaches the upper limit of the temperature, the expansion bag expands to block the storage cavity, so that an electrochemical reaction between electrolyte and an electrode is prevented, the temperature is prevented from being too high, and the high-temperature-resistant lithium battery diaphragm is high-temperature-resistant.

Description

Technical Field

[0001] The invention relates to the technical field of battery separators, in particular to a high-temperature-resistant lithium battery separator. Background Art

[0002] Lithium batteries are batteries that use lithium metal or lithium alloy as anode materials and non-aqueous electrolyte solutions. In the structure of lithium batteries, the diaphragm is one of the key internal components. The performance of the diaphragm determines the interface structure and internal resistance of the battery, and directly affects the battery's capacity, cycle and safety performance. Excellent performance diaphragms play an important role in improving the overall performance of batteries. The main function of the diaphragm 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. Existing lithium battery diaphragms still have certain defects when used, such as;

[0003] Publication number: CN109103398A, proposes: a lithium battery separator, including a frame, the inner wall of the frame is bonded with a film body, the front of the film body is bonded with a support rod, the top and bottom of the support rod are fixedly connected to the inner wall of the frame, the film body includes a base layer, an anti-corrosion layer, a high temperature resistant layer and a ceramic film 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 film layer. The problem of short service life of the existing lithium battery separator is solved by the coordinated use of the frame, the support rod, the film body, the base layer, the anti-corrosion layer, the polyethylene layer, the polypropylene layer, the high temperature resistant layer, the epoxy resin layer, the polyvinylidene fluoride layer and the ceramic film layer. The lithium battery separator has the advantages of long service life, improves the corrosion resistance and high temperature resistance of the lithium battery separator, is convenient for users to use, and improves the practicality of the lithium battery separator.

[0004] In the above document: the corrosion resistance and high temperature resistance of the lithium battery separator are improved by the coordinated use of a frame, a support rod, a film body, a base layer, an anti-corrosion layer, a polyethylene layer, a polypropylene layer, a high temperature resistant layer, an epoxy resin layer, a polyvinylidene fluoride layer and a ceramic film layer. However, when the lithium battery fails and the internal temperature continues to rise, it cannot prevent the temperature of the lithium battery from continuing to rise, and the high temperature resistance performance is poor. Based on this, a lithium battery separator with high temperature resistance is specially proposed to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to provide a high temperature resistant lithium battery separator to solve the problems raised by the above background technology.

[0006] To achieve the above-mentioned object, the present invention provides the following technical solutions: A lithium battery separator with high temperature resistance, comprising: a polyimide-based film, a polypropylene layer, a barrier mechanism and a rebound 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, a ceramic film layer is connected above the rebound mechanism, micropores are provided in the polyimide-based film, the polypropylene layer, the barrier mechanism and the rebound mechanism, and a blocking mechanism is provided in the ceramic film layer;

[0008] The blocking mechanism comprises: a receiving cavity, a positioning belt, an expansion bag and an evaporative liquid. The ceramic membrane layer is provided with a receiving cavity, and the receiving cavity is arranged above the micropores.

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

[0010] Preferably, an end of the positioning belt away from the receiving cavity is connected to an expansion bag.

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

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

[0013] Preferably, two groups of spring-shaped elastic sheets are embedded inside the rubber grid.

[0014] Preferably, an air cavity is provided between the two groups of the circular spring sheets, and the air cavity is opened in the rubber grid.

[0015] Preferably, the barrier mechanism comprises: a polyethylene layer, an empty groove, a polyvinylidene fluoride coating film and a triphenyl phosphate flame retardant, a polyethylene layer is pasted between the polypropylene layer and the rubber grid, and an empty groove is opened in the polyethylene layer.

[0016] Preferably, a polyvinylidene fluoride coating film is connected to the inner wall of the hollow groove.

[0017] Preferably, the polyvinylidene fluoride coating film 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 storage cavity, preventing the electrolyte from reacting electrochemically with the electrode and preventing the temperature from being too high, thereby making the high-temperature resistant lithium battery separator resistant to high temperatures.

[0019] 1. The heat generated by the lithium battery to the high temperature resistant lithium battery separator is evenly dispersed to the entire separator through the ceramic film layer. The boiling point of the evaporating liquid is the same as the upper safety limit temperature of the lithium battery. When the temperature inside the lithium battery reaches the upper limit, the expansion capsule expands rapidly to block the storage cavity, preventing the electrolyte from having an electrochemical reaction with the electrode. The materials of the polypropylene layer and the polyethylene layer are resistant to high temperatures. When the temperature is too high, the polyethylene layer melts and closes the circuit, and the polyethylene of the polyethylene layer penetrates into the polypropylene pores of the polypropylene layer. At the same time, the polypropylene layer also melts and closes the pores to prevent the temperature from being too high, thereby improving the high temperature resistance of the high temperature resistant lithium battery separator;

[0020] 2. The high temperature resistant lithium battery separator rebounds through the spring sheet, rubber grid and thermoplastic polyurethane film to prevent wrinkles from appearing during thermal expansion of the separator, thereby improving the structural strength of the high temperature resistant lithium battery separator;

[0021] 3. The high-temperature resistant lithium battery separator encapsulates the triphenyl phosphate flame retardant through a polyvinylidene fluoride coating film. When the temperature of the lithium battery is about to reach the ignition point, the polyvinylidene fluoride coating film is melted by heat, releasing the triphenyl phosphate flame retardant, inhibiting the combustion of the electrolyte, thereby improving the flame retardant properties of the high-temperature resistant lithium battery separator. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the three-dimensional decomposition structure of the present invention;

[0023] Figure 2 It is a schematic diagram of the three-dimensional structure of the present invention;

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

[0025] Figure 4 It is a schematic diagram of the three-dimensional cross-sectional structure of the ceramic membrane 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 It is a schematic diagram of the three-dimensional cross-sectional structure of the polyethylene layer of the present invention.

[0028] In the figure: 1. polyimide-based film; 2. polypropylene layer; 3. barrier mechanism; 301. polyethylene layer; 302. empty groove; 303. polyvinylidene fluoride coating film; 304. triphenyl phosphate flame retardant; 4. rebound mechanism; 401. rubber grid; 402. thermoplastic polyurethane film; 403. spring-shaped spring; 404. air cavity; 5. ceramic film layer; 6. micropores; 7. blocking mechanism; 701. storage cavity; 702. positioning belt; 703. expansion bladder; 704. evaporating liquid. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] See also Figure 1-Figure 4 The present invention provides a technical solution: a high temperature resistant lithium battery separator, comprising: a polyimide base film 1, a polypropylene layer 2, a barrier mechanism 3 and a rebound mechanism 4; the polyimide base film 1 is connected with the polypropylene layer 2, the polypropylene layer 2 is connected with the barrier mechanism 3, the barrier mechanism 3 is connected with the rebound mechanism 4, the rebound mechanism 4 is connected with a ceramic film layer 5, the polyimide base film 1, the polypropylene layer 2, the barrier mechanism 3 and the rebound mechanism 4 are all connected with the ceramic film layer 5. Micropores 6 are provided, and a blocking mechanism 7 is arranged in the ceramic membrane layer 5; the blocking mechanism 7 includes: a storage cavity 701, a positioning belt 702, an expansion capsule 703 and an evaporative liquid 704. A storage cavity 701 is provided in the ceramic membrane layer 5, and the storage cavity 701 is arranged above the micropores 6. The inner wall of the storage cavity 701 is connected to the positioning belt 702, and the end of the positioning belt 702 away from the storage cavity 701 is connected to the expansion capsule 703, and the expansion capsule 703 is filled with the evaporative liquid 704.

[0031] In specific implementation, the ceramic film layer 5 is used to evenly disperse the heat generated by the lithium battery. When the lithium battery is locally overheated, the heat is quickly conducted and dispersed to the entire diaphragm. The micropores 6 improve the liquid hanging capacity of the entire diaphragm, and also provide more heat expansion space for the membrane body. The positioning belt 702 fixes the expansion capsule 703 in the center of the storage cavity 701. The positioning belt 702 can be made of rubber or other corrosion-resistant flexible materials. The expansion capsule 703 can be made of rubber. The boiling point temperature of the evaporating liquid 704 is the same as the safety upper limit temperature of the lithium battery. When the temperature inside the lithium battery reaches the upper limit, the evaporation in the expansion capsule 703 Liquid 704 vaporizes quickly, causing the expansion bladder 703 to expand rapidly and block the storage cavity 701 to prevent the electrolyte from passing through the micropores 6 and to prevent the electrolyte from reacting electrochemically with the electrodes. The materials of the polypropylene layer 2 and the polyethylene layer 301 are resistant to high temperatures. When the temperature is too high, the polyethylene layer 301 will first melt and close the pores to protect the battery. When the temperature continues to rise, the polyethylene of the polyethylene layer 301 will penetrate into the polypropylene pores of the polypropylene layer 2. At the same time, the polypropylene layer 2 will also melt and close the pores to perform a second protection to prevent the temperature from being too high, thereby improving the high temperature resistance of the high temperature resistant lithium battery separator.

[0032] See also Figure 2-Figure 3 and Figure 5It can be seen that the rebound mechanism 4 includes: a rubber grid 401, a thermoplastic polyurethane film 402, a return spring 403 and an air cavity 404. The rubber grid 401 is pasted between the barrier mechanism 3 and the ceramic membrane layer 5. The thermoplastic polyurethane film 402 is connected to the inner wall of the rubber grid 401. Two groups of return springs 403 are embedded in the rubber grid 401. An air cavity 404 is set between the two groups of return springs 403. The air cavity 404 is opened in the rubber grid 401.

[0033] In a specific implementation, the air cavity 404 can conduct temperature, and the rubber grid 401, the thermoplastic polyurethane film 402 and the air cavity 404 can rebound after deformation, preventing the diaphragm from wrinkling or even breaking when pulled or thermally expanded, thereby improving the structural strength of the high-temperature resistant lithium battery diaphragm.

[0034] See also Figure 1-Figure 3 and Figure 6 It can be seen that the barrier mechanism 3 includes: a polyethylene layer 301, an empty groove 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. The polyethylene layer 301 is provided with an empty groove 302. The inner wall of the empty groove 302 is connected to the polyvinylidene fluoride coating film 303. The polyvinylidene fluoride coating film 303 is filled with triphenyl phosphate flame retardant 304.

[0035] In a specific implementation, a polyvinylidene fluoride coating film 303 is used to encapsulate the triphenyl phosphate flame retardant 304 to prevent the triphenyl phosphate flame retardant 304 from directly dissolving into the electrolyte for storage. When the temperature of the lithium battery is out of control and is about to reach the ignition point, the polyvinylidene fluoride coating film 303 is melted by heat, releasing the triphenyl phosphate flame retardant 304, inhibiting the combustion of the electrolyte, thereby improving the flame retardant properties of the high temperature resistant lithium battery separator.

[0036] In summary, when the high temperature resistant lithium battery separator is used, the lithium battery separator is installed inside the battery to separate the positive and negative electrodes. The electrolyte wets the entire separator through the micropores 6 and the storage cavity 701 and reacts with the positive and negative electrodes of the battery. The polyimide base film 1, the micropores 6, the polypropylene layer 2 and the polyethylene layer 301 are all high temperature resistant materials. The micropores 6 are used for wear resistance and uniform heat conduction, which can ensure that the separator can be used for a long time at high temperatures. The expansion capsule 703 and the evaporation liquid 704 serve as primary protection, the polypropylene layer 2 and the polyethylene layer 301 serve as secondary protection, and the polyvinylidene fluoride package The coating 303 and the triphenyl phosphate flame retardant 304 serve as the third level of protection. When the temperature of the lithium battery rises, the expansion bladder 703 first blocks the storage cavity 701 to prevent the electrolyte from reacting. If the temperature continues to rise and reaches the melting point of the polypropylene layer 2 and the polyethylene layer 301, the micropores 6 in the polypropylene layer 2 and the polyethylene layer 301 are blocked. If the temperature continues to rise and reaches the melting point of the polyvinylidene fluoride coating 303, the triphenyl phosphate flame retardant 304 is released to inhibit the combustion of the electrolyte. The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

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

Claims

1. 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), characterized in that; The polyimide-based film (1) is connected to a polypropylene layer (2) above, the polypropylene layer (2) is connected to a barrier mechanism (3) above, the barrier mechanism (3) is connected to a rebound mechanism (4) above, the rebound mechanism (4) is connected to a ceramic film layer (5) above, the polyimide-based film (1), the polypropylene layer (2), the barrier mechanism (3) and the rebound mechanism (4) are all provided with micropores (6), and the ceramic film layer (5) is provided with a blocking mechanism (7); The blocking mechanism (7) comprises: a storage cavity (701), a positioning belt (702), an expansion bag (703) and an evaporative liquid (704); a storage cavity (701) is provided in the ceramic membrane layer (5); and the storage cavity (701) is arranged above the micropore (6).

2. The high temperature resistant lithium battery separator according to claim 1, characterized in that: A positioning belt (702) is connected to the inner wall of the storage cavity (701).

3. The high temperature resistant lithium battery separator according to claim 2, characterized in that: One end of the positioning belt (702) away from the receiving cavity (701) is connected to an expansion bag (703).

4. The high temperature resistant lithium battery separator according to claim 3, characterized in that: The expansion bag (703) is filled with evaporative liquid (704).

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

6. The high temperature resistant lithium battery separator according to claim 5, characterized in that: Two groups of spring-shaped elastic sheets (403) are embedded inside the rubber grid (401).

7. The high temperature resistant lithium battery separator according to claim 6, characterized in that: An air cavity (404) is provided between the two groups of the reciprocating spring sheets (403), and the air cavity (404) is opened in the rubber grid (401).

8. The high temperature resistant lithium battery separator according to claim 1, characterized in that: The barrier mechanism (3) comprises: a polyethylene layer (301), an empty groove (302), a polyvinylidene fluoride coating film (303) and a triphenyl phosphate flame retardant (304); the polyethylene layer (301) is adhered between the polypropylene layer (2) and the rubber grid (401); and the empty groove (302) is provided in the polyethylene layer (301).

9. The high temperature resistant lithium battery separator according to claim 8, characterized in that: A polyvinylidene fluoride coating film (303) is connected to the inner wall of the hollow groove (302).

10. The high temperature resistant lithium battery separator according to claim 9, characterized in that: The polyvinylidene fluoride coating film (303) is filled with triphenyl phosphate flame retardant (304).

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