A kind of anti-shrinkage lithium battery separator and its production process

Abstract

The present invention discloses an anti-shrinkage lithium battery separator and its production process, which belongs to the technical field of lithium battery separators, and includes a base layer, a reinforcement layer and a flame retardant layer, wherein the base layer is provided with a reinforcement layer, and the reinforcement layer is provided with a flame retardant layer. The present invention solves the problem that the existing lithium battery separator is prone to shrinkage and deformation during use, which causes damage to the lithium battery separator, causes a short circuit when the positive and negative electrode materials contact, and brings a greater hidden danger to the safety of lithium-ion batteries. The problem of low safety in use is that the present invention adopts polyphenylene sulfide and polyetheretherketone to produce the reinforcement layer, and the heat dissipation grooves and heat dissipation holes provided can effectively dissipate heat for the lithium battery separator, and prevent the lithium battery separator from shrinking and deforming due to high temperature accumulation. To a certain extent, the tensile strength, anti-shrinkage and anti-deformation properties of the lithium battery separator can be improved, the lithium battery separator can be prevented from being damaged, the positive and negative electrode materials can be prevented from short circuiting when contacting, and the safety of lithium-ion batteries can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery separators, in particular to an anti-shrinkage lithium battery separator and a production process thereof. Background Art

[0002] 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. A diaphragm with excellent performance plays an important role in improving the overall performance of the battery. The main function of the diaphragm is to separate the positive and negative poles of the battery to prevent the two poles from contacting and short-circuiting. In addition, it also has the function of allowing electrolyte ions to pass through.

[0003] The diaphragm material is non-conductive, and its physical and chemical properties significantly influence battery performance. Different battery types require different diaphragms. For lithium batteries, since the electrolyte is an organic solvent system, a diaphragm material resistant to organic solvents is required. High-strength, thin-film polyolefin porous membranes are generally used.

[0004] When in use, the existing lithium battery separator is prone to shrinkage and deformation under high temperature or external impact, which may cause damage to the lithium battery separator and cause a short circuit between the positive and negative electrode materials, posing a major hidden danger to the safety of lithium-ion batteries and low safety of use. Summary of the Invention

[0005] The purpose of the present invention is to provide a retraction-resistant lithium battery separator and its production process, which can improve the tensile strength, anti-retraction and anti-deformation properties of the lithium battery separator, prevent the lithium battery separator from being damaged, avoid short circuit caused by contact between positive and negative electrode materials, and improve the safety of lithium-ion batteries, thereby solving the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A shrinkage-resistant lithium battery separator comprises a base layer, a reinforcement layer and a flame-retardant layer, wherein the base layer is provided with the reinforcement layer, and the reinforcement layer is provided with the flame-retardant layer, wherein the thickness ratio of the base layer, the reinforcement layer and the flame-retardant layer is 1:1.6-2.4:1.

[0008] Preferably, the base layer is made of polypropylene particles, which are stirred, mixed, plasticized and compacted by an extruder, and a pre-product of a certain shape is extruded from the die of the extruder. The pre-product is strongly extruded and stretched by a calender to form a calendered product with uniform thickness. According to the size requirements of the lithium battery separator, the calendered product is sheared to form the base layer.

[0009] Preferably, the reinforcement layer includes an upper supporting layer and a lower supporting layer, the upper supporting layer and the lower supporting layer are connected, the upper supporting layer is arranged on the flame retardant layer, and the lower supporting layer is arranged on the base layer.

[0010] Preferably, the reinforcement layer further includes transverse reinforcement ribs and longitudinal reinforcement ribs, the transverse reinforcement ribs are transversely arranged on the inner side of the lower support layer, the longitudinal reinforcement ribs are longitudinally arranged on the inner side of the lower support layer, and the transverse reinforcement ribs and the longitudinal reinforcement ribs are connected.

[0011] Preferably, the bottoms of the transverse reinforcing ribs and the longitudinal reinforcing ribs are connected to the lower support layer, and the tops of the transverse reinforcing ribs and the longitudinal reinforcing ribs are connected to the upper support layer.

[0012] Preferably, the transverse reinforcing ribs and the longitudinal reinforcing ribs are staggered and form heat dissipation grooves, wherein heat dissipation holes are provided on the upper support layer and the lower support layer, the positions of the heat dissipation holes and the heat dissipation grooves correspond to each other, and the heat dissipation holes and the heat dissipation grooves are connected.

[0013] Preferably, the upper supporting layer, the lower supporting layer, the transverse reinforcing ribs and the longitudinal reinforcing ribs are all made of polyphenylene sulfide and polyetheretherketone, which are stirred, mixed, plasticized and compacted by an extruder, and a pre-product of a certain shape is extruded from the die of the extruder. The pre-product is strongly extruded and stretched by a calender to form a calendered product with uniform thickness. According to the size requirements of the lithium battery separator, the calendered product is sheared to form an upper supporting layer, a lower supporting layer, transverse reinforcing ribs and longitudinal reinforcing ribs, wherein the mass ratio of polyphenylene sulfide to polyetheretherketone is 5:4-8.

[0014] Preferably, the flame retardant layer is formed by uniformly mixing ultrafine calcium carbonate powder, ultrafine sodium carbonate powder, ceramic microbeads, α-AlO and nano-silicon dioxide, adding aqueous acrylic acid solution thereto, and coating.

[0015] According to another aspect of the present invention, there is provided a production process for the above-mentioned anti-shrinkage lithium battery separator, comprising the following steps:

[0016] S1. Production of base layer:

[0017] The polypropylene pellets are added into the extruder, stirred, mixed, plasticized and compacted by the extruder, and a pre-product of a certain shape is extruded from the die of the extruder;

[0018] The pre-product is strongly extruded and stretched by the calender to form a calendered product with uniform thickness. According to the size requirements of the lithium battery separator, the calendered product is sheared to form the base layer;

[0019] S2, production strengthening layer:

[0020] Add polyphenylene sulfide and polyetheretherketone in proportion to an extruder, stir, mix, plasticize and compact the polyphenylene sulfide and polyetheretherketone in the extruder, and extrude a pre-product of a certain shape from the die of the extruder; strongly extrude and stretch the pre-product in a calender to form a calendered product with uniform thickness; and shear the calendered product according to the size requirements of the lithium battery separator to form an upper support layer, a lower support layer, transverse reinforcing ribs and longitudinal reinforcing ribs;

[0021] The transverse reinforcement ribs and the longitudinal reinforcement ribs are staggered and processed in the lower support layer, and heat dissipation holes are processed on the upper support layer and the lower support layer;

[0022] Processing the upper supporting layer on the lower supporting layer to form a reinforcement layer;

[0023] S3. Production of flame retardant layer:

[0024] Adding ultrafine calcium carbonate powder, ultrafine sodium carbonate powder, ceramic microbeads, α-AlO and nano-silicon dioxide into a mixer, mixing and stirring the ultrafine calcium carbonate powder, ultrafine sodium carbonate powder, ceramic microbeads, α-AlO and nano-silicon dioxide in the mixer, adding an aqueous acrylic acid solution into the mixer, mixing them thoroughly and evenly, and coating the solution on the reinforcing layer to form a flame retardant layer;

[0025] S4. Production of lithium battery separator:

[0026] The reinforcing layer is bonded to the base layer, and the base layer and the reinforcing layer are subjected to cold stretching and hot stretching to form a nanoporous membrane, which is then cut to form a lithium battery separator.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention adopts polyphenylene sulfide and polyetheretherketone to produce the reinforcing layer. The heat dissipation grooves and heat dissipation holes are provided to effectively dissipate heat for the lithium battery separator, thereby preventing the lithium battery separator from shrinking and deforming due to high temperature accumulation. To a certain extent, the tensile strength, anti-shrinkage and anti-deformation properties of the lithium battery separator can be improved, the damage of the lithium battery separator can be prevented, the short circuit caused by contact between the positive and negative electrode materials can be avoided, and the safety of the lithium-ion battery can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the front view of the anti-shrinkage lithium battery separator of the present invention;

[0030] Figure 2 Schematic diagram of the unfolding of the anti-shrinkage lithium battery separator of the present invention;

[0031] Figure 3 is a schematic diagram of the front view of the reinforcement layer of the present invention;

[0032] Figure 4 is an exploded schematic diagram of the reinforcement layer of the present invention;

[0033] Figure 5 For the present invention Figure 4 A in the enlarged view.

[0034] In the figure: 1. base layer; 2. reinforcement layer; 21. upper support layer; 22. lower support layer; 23. transverse reinforcement ribs; 24. longitudinal reinforcement ribs; 25. heat dissipation grooves; 26. heat dissipation holes; 3. flame retardant layer. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0036] In order to solve the problem that the existing lithium battery separator is prone to shrinkage and deformation when in use under high temperature or external impact, which may cause the lithium battery separator to be damaged, causing the positive and negative electrode materials to short-circuit, which brings great hidden dangers to the safety of lithium-ion batteries and its low safety, please refer to Figure 1-Figure 5 , this embodiment provides the following technical solutions:

[0037] Example 1

[0038] A shrinkage-resistant lithium battery separator comprises a base layer 1, a reinforcement layer 2 and a flame-retardant layer 3. The reinforcement layer 2 is arranged on the base layer 1, and the flame-retardant layer 3 is arranged on the reinforcement layer 2. The thickness ratio of the base layer 1, the reinforcement layer 2 and the flame-retardant layer 3 is 1:1.6-2.4:1.

[0039] It should be noted that the added reinforcement layer 2 can improve the tensile strength, anti-retraction and anti-deformation properties of the lithium battery separator. To a certain extent, it can prevent the lithium battery separator from being damaged, avoid short circuits caused by contact between positive and negative electrode materials, and improve the safety of lithium-ion batteries.

[0040] In this embodiment, as the preferred technical solution of the present invention, the base layer 1 uses polypropylene particles as raw material, which are stirred, mixed, plasticized and compacted by an extruder, and a pre-product of a certain shape is extruded from the mouth of the extruder. The pre-product is strongly extruded and stretched by a calender to form a calendered product with uniform thickness. According to the size requirements of the lithium battery isolation membrane, the calendered product is sheared to form the base layer 1.

[0041] In this embodiment, as the preferred technical solution of the present invention, the reinforcing layer 2 includes an upper supporting layer 21 and a lower supporting layer 22, the upper supporting layer 21 and the lower supporting layer 22 are connected, the upper supporting layer 21 is arranged on the flame retardant layer 3, and the lower supporting layer 22 is arranged on the base layer 1.

[0042] In this embodiment, as the preferred technical solution of the present invention, the reinforcement layer 2 also includes transverse reinforcement ribs 23 and longitudinal reinforcement ribs 24. The transverse reinforcement ribs 23 are transversely arranged on the inner side of the lower support layer 22, and the longitudinal reinforcement ribs 24 are longitudinally arranged on the inner side of the lower support layer 22, and the transverse reinforcement ribs 23 and the longitudinal reinforcement ribs 24 are connected.

[0043] In this embodiment, as the preferred technical solution of the present invention, the bottoms of the transverse reinforcing ribs 23 and the longitudinal reinforcing ribs 24 are connected to the lower support layer 22, and the tops of the transverse reinforcing ribs 23 and the longitudinal reinforcing ribs 24 are connected to the upper support layer 21.

[0044] In this embodiment, as the preferred technical solution of the present invention, the transverse reinforcing ribs 23 and the longitudinal reinforcing ribs 24 are staggered and form heat dissipation grooves 25, wherein heat dissipation holes 26 are provided on the upper support layer 21 and the lower support layer 22, and the positions of the heat dissipation holes 26 and the heat dissipation grooves 25 correspond to each other, and the heat dissipation holes 26 and the heat dissipation grooves 25 are connected.

[0045] It should be noted that the heat dissipation grooves 25 and the heat dissipation holes 26 can effectively dissipate heat from the lithium battery separator, thereby preventing the lithium battery separator from shrinking and deforming due to high temperature accumulation.

[0046] In this embodiment, as the preferred technical solution of the present invention, the upper support layer 21, the lower support layer 22, the transverse reinforcing ribs 23 and the longitudinal reinforcing ribs 24 are all made of polyphenylene sulfide and polyetheretherketone, which are stirred, mixed, plasticized and compacted by an extruder, and a pre-product of a certain shape is extruded from the mouth of the extruder. The pre-product is strongly extruded and stretched by a calender to form a calendered product with uniform thickness. According to the size requirements of the lithium battery isolation membrane, the calendered product is sheared to form the upper support layer 21, the lower support layer 22, the transverse reinforcing ribs 23 and the longitudinal reinforcing ribs 24, wherein the mass ratio of polyphenylene sulfide to polyetheretherketone is 5:4-8.

[0047] It should be noted that polyphenylene sulfide PPS is a new type of high-performance thermoplastic resin with the advantages of high mechanical strength, high temperature resistance, chemical resistance, flame retardancy, good thermal stability, and excellent electrical properties. It is widely used in electronics, automobiles, machinery, and chemical fields.

[0048] It should be noted that polyetheretherketone (PEEK) is a polymer composed of repeating units containing one ketone bond and two ether bonds in the main chain structure. It is a special polymer material with physical and chemical properties such as high temperature resistance and chemical corrosion resistance. It is a type of semi-crystalline polymer material that can be used as a high-temperature resistant structural material and electrical insulation material. It can be composited with glass fiber or carbon fiber to prepare reinforced materials. It has high mechanical strength, high temperature resistance, impact resistance, flame retardancy, acid and alkali resistance, hydrolysis resistance, wear resistance, fatigue resistance, radiation resistance and good electrical properties.

[0049] Therefore, polyphenylene sulfide and polyetheretherketone are used to prepare the upper support layer 21, the lower support layer 22, the transverse reinforcing ribs 23 and the longitudinal reinforcing ribs 24, and the reinforcing layer 2 is produced by the upper support layer 21, the lower support layer 22, the transverse reinforcing ribs 23 and the longitudinal reinforcing ribs 24. To a certain extent, the tensile strength, anti-retraction and anti-deformation properties of the lithium battery separator can be improved, the lithium battery separator can be prevented from being damaged, the short circuit caused by the contact of the positive and negative electrode materials can be avoided, and the safety of the lithium-ion battery can be improved.

[0050] In this embodiment, as a preferred technical solution of the present invention, the flame retardant layer 3 is formed by uniformly mixing ultrafine calcium carbonate powder, ultrafine sodium carbonate powder, ceramic microbeads, α-AlO and nano-silicon dioxide, adding aqueous acrylic acid solution thereto, and coating.

[0051] In order to better illustrate the production process of an anti-shrinkage lithium battery separator, this embodiment provides a production process of an anti-shrinkage lithium battery separator, including the following steps:

[0052] S1. Production of base layer 1:

[0053] The polypropylene pellets are added into the extruder, stirred, mixed, plasticized and compacted by the extruder, and a pre-product of a certain shape is extruded from the die of the extruder;

[0054] The pre-product is strongly extruded and stretched by a calender to form a calendered product with uniform thickness. According to the size requirements of the lithium battery separator, the calendered product is sheared to form a base layer 1;

[0055] S2, production strengthening layer 2:

[0056] Polyphenylene sulfide and polyetheretherketone are added into an extruder in proportion, stirred, mixed, plasticized and compacted by the extruder, and a pre-product of a certain shape is extruded from the die of the extruder; the pre-product is strongly extruded and stretched by a calender to form a calendered product with uniform thickness; the calendered product is sheared according to the size requirements of the lithium battery separator to form an upper support layer 21, a lower support layer 22, transverse reinforcing ribs 23 and longitudinal reinforcing ribs 24;

[0057] The transverse reinforcing ribs 23 and the longitudinal reinforcing ribs 24 are staggered in the lower supporting layer 22, and heat dissipation holes 26 are processed on the upper supporting layer 21 and the lower supporting layer 22;

[0058] Processing the upper supporting layer 21 on the lower supporting layer 22 to form the reinforcement layer 2;

[0059] S3, production of flame retardant layer 3:

[0060] Ultrafine calcium carbonate powder, ultrafine sodium carbonate powder, ceramic microbeads, α-AlO and nano-silicon dioxide are added to a mixer, and the ultrafine calcium carbonate powder, ultrafine sodium carbonate powder, ceramic microbeads, α-AlO and nano-silicon dioxide are mixed and stirred in the mixer, and an aqueous acrylic acid solution is added to the mixer and mixed thoroughly, and then coated on the reinforcing layer 2 to form a flame retardant layer 3;

[0061] S4. Production of lithium battery separator:

[0062] The reinforcement layer 2 is bonded to the base layer 1, and the base layer 1 and the reinforcement layer 2 are subjected to cold stretching and hot stretching to form a nanoporous membrane, which is then cut to form a lithium battery separator.

[0063] Example 2

[0064] A shrinkage-resistant lithium battery separator comprises a base layer 1, a reinforcement layer 2 and a flame-retardant layer 3. The reinforcement layer 2 is arranged on the base layer 1, and the flame-retardant layer 3 is arranged on the reinforcement layer 2. The thickness ratio of the base layer 1, the reinforcement layer 2 and the flame-retardant layer 3 is 1:1.6-2.4:1.

[0065] It should be noted that the added reinforcement layer 2 can improve the tensile strength, anti-retraction and anti-deformation properties of the lithium battery separator. To a certain extent, it can prevent the lithium battery separator from being damaged, avoid short circuits caused by contact between positive and negative electrode materials, and improve the safety of lithium-ion batteries.

[0066] In this embodiment, as the preferred technical solution of the present invention, the base layer 1 uses polypropylene particles as raw material, which are stirred, mixed, plasticized and compacted by an extruder, and a pre-product of a certain shape is extruded from the mouth of the extruder. The pre-product is strongly extruded and stretched by a calender to form a calendered product with uniform thickness. According to the size requirements of the lithium battery isolation membrane, the calendered product is sheared to form the base layer 1.

[0067] In this embodiment, as the preferred technical solution of the present invention, the reinforcing layer 2 includes an upper supporting layer 21 and a lower supporting layer 22, the upper supporting layer 21 and the lower supporting layer 22 are connected, the upper supporting layer 21 is arranged on the flame retardant layer 3, and the lower supporting layer 22 is arranged on the base layer 1.

[0068] In this embodiment, as the preferred technical solution of the present invention, the reinforcement layer 2 also includes transverse reinforcement ribs 23 and longitudinal reinforcement ribs 24. The transverse reinforcement ribs 23 are transversely arranged on the inner side of the lower support layer 22, and the longitudinal reinforcement ribs 24 are longitudinally arranged on the inner side of the lower support layer 22, and the transverse reinforcement ribs 23 and the longitudinal reinforcement ribs 24 are connected.

[0069] In this embodiment, as the preferred technical solution of the present invention, the bottoms of the transverse reinforcing ribs 23 and the longitudinal reinforcing ribs 24 are connected to the lower support layer 22, and the tops of the transverse reinforcing ribs 23 and the longitudinal reinforcing ribs 24 are connected to the upper support layer 21.

[0070] In this embodiment, as a preferred technical solution of the present invention, the transverse reinforcing ribs 23 and the longitudinal reinforcing ribs 24 are staggered and form heat dissipation grooves 25 .

[0071] In this embodiment, as the preferred technical solution of the present invention, the upper support layer 21, the lower support layer 22, the transverse reinforcing ribs 23 and the longitudinal reinforcing ribs 24 are all made of polyphenylene sulfide and polyetheretherketone, which are stirred, mixed, plasticized and compacted by an extruder, and a pre-product of a certain shape is extruded from the mouth of the extruder. The pre-product is strongly extruded and stretched by a calender to form a calendered product with uniform thickness. According to the size requirements of the lithium battery isolation membrane, the calendered product is sheared to form the upper support layer 21, the lower support layer 22, the transverse reinforcing ribs 23 and the longitudinal reinforcing ribs 24, wherein the mass ratio of polyphenylene sulfide to polyetheretherketone is 5:4-8.

[0072] It should be noted that polyphenylene sulfide PPS is a new type of high-performance thermoplastic resin with the advantages of high mechanical strength, high temperature resistance, chemical resistance, flame retardancy, good thermal stability, and excellent electrical properties. It is widely used in electronics, automobiles, machinery, and chemical fields.

[0073] It should be noted that polyetheretherketone (PEEK) is a polymer composed of repeating units containing one ketone bond and two ether bonds in the main chain structure. It is a special polymer material with physical and chemical properties such as high temperature resistance and chemical corrosion resistance. It is a type of semi-crystalline polymer material that can be used as a high-temperature resistant structural material and electrical insulation material. It can be composited with glass fiber or carbon fiber to prepare reinforced materials. It has high mechanical strength, high temperature resistance, impact resistance, flame retardancy, acid and alkali resistance, hydrolysis resistance, wear resistance, fatigue resistance, radiation resistance and good electrical properties.

[0074] Therefore, polyphenylene sulfide and polyetheretherketone are used to prepare the upper support layer 21, the lower support layer 22, the transverse reinforcing ribs 23 and the longitudinal reinforcing ribs 24, and the reinforcing layer 2 is produced by the upper support layer 21, the lower support layer 22, the transverse reinforcing ribs 23 and the longitudinal reinforcing ribs 24. To a certain extent, the tensile strength, anti-retraction and anti-deformation properties of the lithium battery separator can be improved, the lithium battery separator can be prevented from being damaged, the short circuit caused by the contact of the positive and negative electrode materials can be avoided, and the safety of the lithium-ion battery can be improved.

[0075] In this embodiment, as a preferred technical solution of the present invention, the flame retardant layer 3 is formed by uniformly mixing ultrafine calcium carbonate powder, ultrafine sodium carbonate powder, ceramic microbeads, α-AlO and nano-silicon dioxide, adding aqueous acrylic acid solution thereto, and coating.

[0076] Compared with the first embodiment, the structure of the heat dissipation hole 26 is eliminated in the second embodiment. The lithium battery separator is produced by the same production process as the first embodiment, and the production step of the heat dissipation hole 26 is eliminated accordingly.

[0077] Example 3

[0078] A shrinkage-resistant lithium battery separator comprises a base layer 1, a reinforcement layer 2 and a flame-retardant layer 3. The reinforcement layer 2 is arranged on the base layer 1, and the flame-retardant layer 3 is arranged on the reinforcement layer 2. The thickness ratio of the base layer 1, the reinforcement layer 2 and the flame-retardant layer 3 is 1:1.6-2.4:1.

[0079] It should be noted that the added reinforcement layer 2 can improve the tensile strength, anti-retraction and anti-deformation properties of the lithium battery separator. To a certain extent, it can prevent the lithium battery separator from being damaged, avoid short circuits caused by contact between positive and negative electrode materials, and improve the safety of lithium-ion batteries.

[0080] In this embodiment, as the preferred technical solution of the present invention, the base layer 1 uses polypropylene particles as raw material, which are stirred, mixed, plasticized and compacted by an extruder, and a pre-product of a certain shape is extruded from the mouth of the extruder. The pre-product is strongly extruded and stretched by a calender to form a calendered product with uniform thickness. According to the size requirements of the lithium battery isolation membrane, the calendered product is sheared to form the base layer 1.

[0081] In this embodiment, as the preferred technical solution of the present invention, the reinforcing layer 2 includes an upper supporting layer 21 and a lower supporting layer 22, the upper supporting layer 21 and the lower supporting layer 22 are connected, the upper supporting layer 21 is arranged on the flame retardant layer 3, and the lower supporting layer 22 is arranged on the base layer 1.

[0082] In this embodiment, as the preferred technical solution of the present invention, the upper support layer 21 and the lower support layer 22 are both made of polyphenylene sulfide and polyetheretherketone (PEEK), which are stirred, mixed, plasticized and compacted by an extruder, and a pre-product of a certain shape is extruded from the mouth of the extruder. The pre-product is strongly extruded and stretched by a calender to form a calendered product with uniform thickness. According to the size requirements of the lithium battery isolation membrane, the calendered product is sheared to form the upper support layer 21 and the lower support layer 22, wherein the mass ratio of polyphenylene sulfide to polyetheretherketone is 5:4-8.

[0083] It should be noted that polyphenylene sulfide PPS is a new type of high-performance thermoplastic resin with the advantages of high mechanical strength, high temperature resistance, chemical resistance, flame retardancy, good thermal stability, and excellent electrical properties. It is widely used in electronics, automobiles, machinery, and chemical fields.

[0084] It should be noted that polyetheretherketone (PEEK) is a polymer composed of repeating units containing one ketone bond and two ether bonds in the main chain structure. It is a special polymer material with physical and chemical properties such as high temperature resistance and chemical corrosion resistance. It is a type of semi-crystalline polymer material that can be used as a high-temperature resistant structural material and electrical insulation material. It can be composited with glass fiber or carbon fiber to prepare reinforced materials. It has high mechanical strength, high temperature resistance, impact resistance, flame retardancy, acid and alkali resistance, hydrolysis resistance, wear resistance, fatigue resistance, radiation resistance and good electrical properties.

[0085] In this embodiment, as a preferred technical solution of the present invention, the flame retardant layer 3 is formed by uniformly mixing ultrafine calcium carbonate powder, ultrafine sodium carbonate powder, ceramic microbeads, α-AlO and nano-silicon dioxide, adding aqueous acrylic acid solution thereto, and coating.

[0086] Compared with Example 1, the structures of the heat dissipation holes 26, the transverse reinforcing ribs 23 and the longitudinal reinforcing ribs 24 are eliminated in Example 3. The lithium battery isolation membrane is produced using the same production process as Example 1, and the production steps of the heat dissipation holes 26, the transverse reinforcing ribs 23 and the longitudinal reinforcing ribs 24 are correspondingly eliminated.

[0087] Comparative Example

[0088] A shrinkage-resistant lithium battery separator comprises a base layer 1 and a flame-retardant layer 3. The flame-retardant layer 3 is provided on the base layer 1, wherein the thickness ratio of the base layer 1 to the flame-retardant layer 3 is 1:1.

[0089] In this embodiment, as the preferred technical solution of the present invention, the base layer 1 uses polypropylene particles as raw material, which are stirred, mixed, plasticized and compacted by an extruder, and a pre-product of a certain shape is extruded from the mouth of the extruder. The pre-product is strongly extruded and stretched by a calender to form a calendered product with uniform thickness. According to the size requirements of the lithium battery isolation membrane, the calendered product is sheared to form the base layer 1.

[0090] In this embodiment, as a preferred technical solution of the present invention, the flame retardant layer 3 is formed by uniformly mixing ultrafine calcium carbonate powder, ultrafine sodium carbonate powder, ceramic microbeads, α-AlO and nano-silicon dioxide, adding aqueous acrylic acid solution thereto, and coating.

[0091] Compared with Example 1, the structure of the reinforcement layer 2 is eliminated in the comparative example. The lithium battery separator is produced using the same production process as Example 1, and the production step of the reinforcement layer 2 is eliminated accordingly.

[0092] The performance tests were performed on the lithium battery separators produced in Examples 1-3 and the comparative example. The performance test results of the lithium battery separators are shown in Table 1:

[0093] Table 1: Performance test results of lithium battery separators

[0094]

[0095] Therefore, it can be seen from the above table that the lithium battery separators produced in Examples 1-3 all have good tensile strength, anti-shrinkage and anti-deformation properties.

[0096] Among them, compared with Example 1, the anti-retraction and anti-deformation performance of Example 2 is reduced. Since the heat dissipation holes 26 are not added in Example 2, the anti-retraction and anti-deformation performance of the lithium battery isolation membrane is reduced, which shows that the heat dissipation holes 26 can improve the anti-retraction and anti-deformation performance of the lithium battery isolation membrane.

[0097] Among them, compared with Example 2, the tensile strength, anti-retraction and anti-deformation properties of Example 3 are all reduced. Since the transverse reinforcing ribs 23 and the longitudinal reinforcing ribs 24 are not added in Example 3, the tensile strength, anti-retraction and anti-deformation properties of the lithium battery isolation membrane are all reduced, indicating that the transverse reinforcing ribs 23 and the longitudinal reinforcing ribs 24 can improve the tensile strength, anti-retraction and anti-deformation properties of the lithium battery isolation membrane.

[0098] Among them, compared with Example 3, the tensile strength, anti-retraction and anti-deformation properties of the comparative example are all reduced. Since the upper support layer 21 and the lower support layer 22 are not added in the comparative example, the tensile strength, anti-retraction and anti-deformation properties of the lithium battery isolation membrane are all reduced, indicating that the upper support layer 21 and the lower support layer 22 can improve the tensile strength, anti-retraction and anti-deformation properties of the lithium battery isolation membrane.

[0099] Therefore, polyphenylene sulfide and polyetheretherketone are used to produce the reinforcing layer 2. The heat dissipation grooves 25 and heat dissipation holes 26 are provided to effectively dissipate heat for the lithium battery separator, thereby preventing the lithium battery separator from shrinking and deforming due to high temperature accumulation. To a certain extent, the tensile strength, anti-shrinkage and anti-deformation properties of the lithium battery separator can be improved, the damage of the lithium battery separator can be prevented, the short circuit caused by the contact of the positive and negative electrode materials can be avoided, and the safety of the lithium-ion battery can be improved.

[0100] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0101] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A retraction-resistant lithium battery separator, comprising a base layer (1), a reinforcement layer (2) and a flame retardant layer (3), characterized in that: A reinforcing layer (2) is provided on the base layer (1), and a flame retardant layer (3) is provided on the reinforcing layer (2), wherein the thickness ratio of the base layer (1), the reinforcing layer (2) and the flame retardant layer (3) is 1:1.6-2.4:1, the reinforcing layer (2) comprises an upper supporting layer (21) and a lower supporting layer (22), the upper supporting layer (21) and the lower supporting layer (22) are connected, the upper supporting layer (21) is provided on the flame retardant layer (3), and the lower supporting layer (22) is provided on the base layer (1). The reinforcing layer (2) further comprises transverse reinforcing ribs (23) and longitudinal reinforcing ribs (24), wherein the transverse reinforcing ribs (23) are transversely arranged on the inner side of the lower supporting layer (22), and the longitudinal reinforcing ribs (24) are longitudinally arranged on the inner side of the lower supporting layer (22), and the transverse reinforcing ribs (23) and the longitudinal reinforcing ribs (24) are connected, and the upper supporting layer (21), the lower supporting layer (22), the transverse reinforcing ribs (23) and the longitudinal reinforcing ribs (24) are all made of polyphenylene sulfide and polyetheretherketone.

2. The anti-shrinkage lithium battery separator according to claim 1, characterized in that: The base layer (1) is made of polypropylene particles, which are stirred, mixed, plasticized and compacted by an extruder, and a pre-product of a certain shape is extruded from the die of the extruder. The pre-product is strongly extruded and stretched by a calender to form a calendered product with uniform thickness. The calendered product is sheared according to the size requirements of the lithium battery separator to form the base layer (1).

3. The anti-shrinkage lithium battery separator according to claim 2, characterized in that: The bottoms of the transverse reinforcing ribs (23) and the longitudinal reinforcing ribs (24) are both connected to the lower support layer (22), and the tops of the transverse reinforcing ribs (23) and the longitudinal reinforcing ribs (24) are both connected to the upper support layer (21).

4. The anti-shrinkage lithium battery separator according to claim 3, characterized in that: The transverse reinforcing ribs (23) and the longitudinal reinforcing ribs (24) are staggered and form heat dissipation grooves (25), wherein heat dissipation holes (26) are provided on both the upper support layer (21) and the lower support layer (22), and the positions of the heat dissipation holes (26) and the heat dissipation grooves (25) correspond to each other, and the heat dissipation holes (26) and the heat dissipation grooves (25) are connected.

5. The anti-shrinkage lithium battery separator according to claim 4, characterized in that: Polyphenylene sulfide and polyetheretherketone are stirred, mixed, plasticized and compacted by an extruder, and a pre-product of a certain shape is extruded from the die of the extruder. The pre-product is strongly extruded and stretched by a calender to form a calendered product with uniform thickness. According to the size requirements of the lithium battery separator, the calendered product is sheared to form an upper support layer (21), a lower support layer (22), transverse reinforcing ribs (23) and longitudinal reinforcing ribs (24), wherein the mass ratio of polyphenylene sulfide to polyetheretherketone is 5:4-8.

6. The anti-shrinkage lithium battery separator according to claim 5, characterized in that: The flame retardant layer (3) is formed by uniformly mixing ultrafine calcium carbonate powder, ultrafine sodium carbonate powder, ceramic microbeads, α-AlO and nano-silicon dioxide, adding an aqueous acrylic acid solution thereto, and coating.

7. A process for producing an anti-shrinkage lithium battery separator according to claim 6, characterized in that: The steps include: S1. Production of base layer (1): The polypropylene pellets are added into the extruder, stirred, mixed, plasticized and compacted by the extruder, and a pre-product of a certain shape is extruded from the die of the extruder; The pre-product is strongly extruded and stretched by a calender to form a calendered product with uniform thickness, and the calendered product is sheared according to the size requirements of the lithium battery separator to form a base layer (1); S2, production reinforcement layer (2): Adding polyphenylene sulfide and polyetheretherketone into an extruder in proportion, stirring, mixing, plasticizing and compacting the polyphenylene sulfide and polyetheretherketone through the extruder, and extruding a pre-product of a certain shape from the die of the extruder; strongly extruding and stretching the pre-product through a calender to form a calendered product with uniform thickness; shearing the calendered product according to the size requirements of the lithium battery separator to form an upper support layer (21), a lower support layer (22), transverse reinforcing ribs (23) and longitudinal reinforcing ribs (24); The transverse reinforcing ribs (23) and the longitudinal reinforcing ribs (24) are staggered and processed in the lower supporting layer (22), and heat dissipation holes (26) are processed on the upper supporting layer (21) and the lower supporting layer (22); Processing the upper supporting layer (21) on the lower supporting layer (22) to form a reinforcing layer (2); S3, production of flame retardant layer (3): Adding ultrafine calcium carbonate powder, ultrafine sodium carbonate powder, ceramic microbeads, α-AlO and nano-silicon dioxide into a mixer, mixing and stirring the ultrafine calcium carbonate powder, ultrafine sodium carbonate powder, ceramic microbeads, α-AlO and nano-silicon dioxide in the mixer, adding an aqueous acrylic acid solution into the mixer, mixing them thoroughly and evenly, and coating the solution on the reinforcing layer (2) to form a flame retardant layer (3); S4. Production of lithium battery separator: The reinforcement layer (2) is bonded to the base layer (1), and the base layer (1) and the reinforcement layer (2) are subjected to cold stretching and hot stretching to form a nanoporous membrane, which is then cut to form a lithium battery separator.

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