Formula and preparation method of modified PET non-woven fabric matrix polymer electrolyte membrane

Abstract

The invention discloses a formula of an electrolyte membrane. The formula of a non-woven fabric comprises PET (Polyethylene Terephthalate) fiber, tencel fibrillated fiber and a radiation sensitive agent, the formula of the polymer electrolyte comprises PEO powder, lithium salt, a heat stabilizer, an antioxidant and a plasticizer; the invention also discloses a preparation method of the electrolyte membrane, which comprises the following steps: firstly preparing the modified PET non-woven fabric, adding the PET fiber, the tencel fibril chemical fiber and the radiation sensitive agent into deionized water, carrying out planetary stirring and dispersion, then putting into a sealing bag, introducing nitrogen, carrying out electron beam irradiation, and sequentially carrying out dehydration, forming, flattening, drying and flattening to form the modified PET non-woven fabric; preparing an electrolyte membrane: adding a plasticizer, a stabilizer, a lithium salt and an antioxidant into the PEO powder, stirring to form a polymer electrolyte, extruding the polymer electrolyte to the surface of the modified PET non-woven fabric, compacting and cooling to form the electrolyte membrane; the modified PET non-woven fabric matrix polymer electrolyte membrane prepared by the formula and the preparation method has better mechanical strength and ionic conductivity, and is high in processing efficiency and low in cost.

Description

Technical Field

[0001] The invention relates to the field of composite polymer materials and polymer material film preparation, and in particular to a formula and a preparation method of a modified PET non-woven fabric matrix polymer electrolyte membrane. Background Art

[0002] Lithium-ion batteries are still the type of energy storage battery with the highest energy density and are widely used in electric vehicles, electronic products and other fields. Current lithium-ion batteries still use liquid batteries as the main technology. Since they still use organic electrolytes to provide the basis for ion exchange, the leakage of low-flash-point solvents they contain may cause problems such as battery combustion. Therefore, current lithium-ion batteries mainly rely on the setting of external auxiliary packaging structures, sealing structures and reinforcement structures to increase the battery's anti-leakage performance.

[0003] In view of the safety issues of liquid batteries with organic electrolytes, gel polymer lithium-ion battery technology and solid polymer lithium-ion battery technology are gradually emerging, which mainly rely on gel or solid electrolytes for lithium ion conduction; this type of lithium-ion battery has a good solid-solid interface, low processing technology difficulty and high application safety factor, becoming an important research direction for liquid lithium-ion batteries to replace traditional organic electrolytes.

[0004] For gel polymer or solid polymer lithium-ion battery technology, polyethylene oxide (PEO) is generally used as the polymer electrolyte membrane. However, the polymer electrolyte formed by PEO and lithium salt has low ionic conductivity at room temperature, and the polymer electrolyte formed by the composite of PEO and lithium salt cannot effectively form a film or the mechanical properties (i.e., mechanical properties) of the prepared membrane are poor, making it difficult to form industrial mass production and thus difficult to apply on a large scale.

[0005] Some public technologies show that some people use hot pressing method to prepare composite polymer electrolyte membrane of polyvinylidene fluoride (PVDF) and PEO, but the prepared electrolyte membrane has poor mechanical properties, which makes it easy for lithium dendrites to penetrate the electrolyte membrane and cause short circuit of the battery, posing a great risk to application safety. In addition, in the process of membrane preparation, due to the problem of formula components, only "sheet-to-sheet" production can be adopted, and it is difficult to achieve high-efficiency batch processing of "roll-to-roll".

[0006] Therefore, in order to solve the problems of difficult film formation, poor membrane mechanical properties, and difficulty in mass production of the polymer electrolyte membrane used in the above-mentioned polymer all-solid-state batteries, it is necessary to provide a new type of polymer electrolyte membrane. Summary of the invention

[0007] The main purpose of the present invention is to solve the problems of the prior art in which polymer electrolyte membranes used in gel polymer or solid polymer lithium ion batteries (i.e., membranes prepared by using PEO and lithium salt or using PVDF and PEO), such as difficulty in film formation, poor membrane mechanical properties, lithium dendrites easily penetrating the electrolyte membrane to cause short circuit, and difficulty in mass production, and a polymer electrolyte membrane formula and preparation method based on a modified PET non-woven fabric substrate are proposed.

[0008] In one aspect, the present invention provides a formula of a modified PET nonwoven matrix polymer electrolyte membrane,

[0009] The formula of the modified PET nonwoven fabric and the weight proportions of each component are:

[0010] PET fiber: 80 to 120 parts;

[0011] Tencel fibrillated fiber: 5 to 20 parts;

[0012] Radiation sensitizer: 0.5 to 2.0 parts;

[0013] The formula of polymer electrolyte and the weight proportions of each component are:

[0014] PEO powder: 80 to 120 parts;

[0015] Lithium salt: 10 to 20 parts;

[0016] Heat stabilizer: 5 to 20 parts;

[0017] Antioxidant: 0.5 to 1.0 parts;

[0018] Plasticizer: 5 to 20 parts.

[0019] Preferably, the formula of the modified PET nonwoven fabric and the weight proportions of each component are:

[0020] PET fiber: 100 parts;

[0021] Tencel fibrillated fiber: 15 parts;

[0022] Radiosensitizer: 1 part;

[0023] The formula of polymer electrolyte and the weight proportions of each component are:

[0024] PEO powder: 100 parts;

[0025] Lithium salt: 15 parts;

[0026] Heat stabilizer: 15 parts;

[0027] Antioxidant: 1 part;

[0028] Plasticizer: 15 parts.

[0029] Preferably, the radiation sensitizer is one of vinyl bromide or vinyl chloride.

[0030] Preferably, the formula of the modified PET nonwoven fabric further comprises a hydrophilic acrylic emulsion in an amount of 1 to 5 parts by weight, preferably 3 parts by weight.

[0031] Preferably, the molecular weight of PEO is 100,000 to 3,000,000.

[0032] Preferably, the heat stabilizer is sodium stearate, zinc stearate or an organic tin stabilizer or a mixture of several thereof.

[0033] Preferably, the plasticizer is paraffin oil, white mineral oil or glycerol.

[0034] On the other hand, the present invention provides a method for preparing a modified PET non-woven fabric matrix polymer electrolyte membrane, which is prepared by using the above polymer electrolyte membrane formula through the following steps:

[0035] S10: preparing a modified PET nonwoven fabric;

[0036] S110: taking deionized water, adding PET fibers, Tencel fibrillated fibers and a radiation sensitizer into the deionized water, and performing planetary stirring to disperse the fibers to form a first mixture;

[0037] S120: taking a sealed bag, placing the first mixture in the sealed bag, introducing nitrogen, and then sealing the bag to form a sealed material bag of the first mixture;

[0038] S130: irradiating the first mixture sealing material bag with an electron beam, the first mixture forms an irradiated slurry, pouring out the irradiated slurry, and sequentially performing dehydration, forming, leveling, drying, and flattening processes to form a modified PET non-woven fabric;

[0039] S20: Preparation of modified PET non-woven fabric matrix polymer electrolyte membrane:

[0040] S210: adding a plasticizer, a heat stabilizer, a lithium salt and an antioxidant to a PEO powder, mixing and stirring to form a polymer electrolyte;

[0041] S220: Extruding the polymer electrolyte onto the surface of the modified PET non-woven fabric, and sequentially compacting and cooling the polymer electrolyte membrane on the modified PET non-woven fabric matrix.

[0042] Preferably, the absorbed dose of irradiation is 10 KGy to 50 KGy.

[0043] Preferably, the porosity of the modified PET nonwoven fabric is 15% to 65%.

[0044] Preferably, it is characterized in that:

[0045] The processing steps of S220 are: take a first release film and a second release film, set the first release film on the lower surface of the modified PET non-woven fabric, extrude the polymer electrolyte to the upper surface of the modified PET non-woven fabric, set the second release film on the upper surface of the modified PET non-woven fabric, compact and cool in sequence to form a polymer electrolyte membrane.

[0046] Preferably, the processing steps of S220 are:

[0047] S2210: The first release film and the second release film are both in roll form and are placed on an unwinder, and the modified PET non-woven fabric is rolled and placed on the unwinder;

[0048] S2220: unwinding and laminating the first release film and the modified PET non-woven fabric to form a first PET film;

[0049] S2230: using a screw extruder to heat the polymer electrolyte to a molten state, and extruding the polymer electrolyte to one side of the modified PET non-woven fabric of the first PET film to form a second PET film;

[0050] S2240: The second release film is laminated on the second PET film by unwinding, and is compacted by a pressing roller, cooled by a cooling roller, and then rolled up to form a rolled modified PET non-woven fabric matrix polymer electrolyte membrane.

[0051] In the polymer electrolyte film formula of the technical solution of the present invention, Tencel fibrillated fibers are added, and the higher crystallinity and orientation of Tencel fibers can be used to effectively make up for and improve the deficiencies of PET fibers, and a modified PET non-woven fabric is formed with PET during film formation, which has better polymerization performance and better graft copolymerization effect; a plasticizer is used in the formula, and paraffin oil, white mineral oil or glycerol with low melting point, good thermal stability, high temperature lubricity and high plasticization efficiency are selected, which can reduce the glass transition temperature of PEO and the melt viscosity during molding and processing, improve the fluidity of PEO in the molten state, and form a PEO, lithium salt and other additives. The blend has more lubricating and smooth extrudable performance conditions, and can be smoothly melted and extruded during subsequent extrusion processing, providing basic conditions for batch roll-to-roll processing; the preparation method of the polymer electrolyte film formula, for the preparation of modified PET non-woven fabrics, PET, Tencel fibrillated fibers and radiation sensitizers are blended, and electron beam irradiation technology is used to make the two undergo graft copolymerization reaction. Electron beam irradiation has the advantages of strong processability, non-toxicity and pollution-free, and high reaction controllability, and improves the grafting rate between Tencel fibrillated fibers and PET. The grafting degree is more sufficient and uniform, and the modified PE formed by processing The T nonwoven fabric has lower porosity, higher mechanical strength, and better penetration barrier against lithium dendrites. The radiation sensitizer plays a catalytic role during electron beam irradiation, increases the ability of the irradiated object to absorb electrons, improves the graft copolymerization rate, and reduces the amount of electron beam irradiation. The formula of the present invention has the characteristics of being able to use the electron beam irradiation preparation method to form a modified PET nonwoven fabric with high mechanical strength, and to form a PEO polymer electrolyte that can be continuously extruded. The modified PET nonwoven fabric and PEO polymer electrolyte prepared based on the above formula further realize a continuous batch processing process that can be processed roll-to-roll, and by adopting a roll-shaped The modified PET non-woven fabric, the first release film in a roll, and the second release film in a roll form a continuous processing process of unwinding, release film lamination and winding. Compared with the currently used "sheet-to-sheet" processing process, the processing efficiency is significantly improved, and the uniformity, reliability and mechanical properties of the film are significantly improved; the overall technology is formed by adjusting the formula to provide a modified PET non-woven fabric that can be prepared by electron beam irradiation, adjusting the formula to provide a polymer electrolyte that can be formed by continuous extrusion processing, and then a high-reliability modified PET non-woven fabric matrix polymer electrolyte membrane with good film-forming properties and membrane mechanical properties is formed through a roll-to-roll preparation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0053] Figure 1 Schematic diagram of a process for preparing a polymer electrolyte membrane according to an embodiment of the present invention;

[0054] Figure 2 A process flow chart for forming a roll-to-roll polymer electrolyte membrane according to an embodiment of the present invention;

[0055] Figure 3 A schematic diagram of a process flow for forming a roll-to-roll polymer electrolyte membrane according to an embodiment of the present invention;

[0056] Figure 4 This is a scanning electron microscope image of a PET nonwoven fabric produced using the existing formula and production process;

[0057] Figure 5 It is a scanning electron microscope image of the modified PET nonwoven fabric prepared by the embodiment of the present invention. DETAILED DESCRIPTION

[0058] 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.

[0059] In the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0060] The embodiment of the present invention first provides a formula of a modified PET non-woven fabric matrix polymer electrolyte membrane, wherein:

[0061] The formula of modified PET non-woven fabric is:

[0062] PET fiber: 80 to 120 parts; PET fiber material is made into non-woven fabric, which serves as a supporting layer for polymer electrolyte materials such as PEO, forming a basic carrier and support body for polymer electrolyte materials; the PET fiber has a fineness of 0.05d to 20d, a diameter of 2μm to 30μm, and a length of 3mm to 30mm. More preferably, the fineness is 0.05 to 5d, the diameter is 2μm to 10μm, and the length is 3mm to 10mm.

[0063] Tencel fibrillated fibers: 5 to 20 parts; in this embodiment, the Tencel fibrillated fibers are composited with PET fibers to form a graft copolymer, and a non-woven fabric with a tighter and more stable network structure is prepared through the preparation method, thereby reducing the porosity of the non-woven fabric, realizing industrial processing, and preventing lithium dendrites from piercing the polymer electrolyte membrane; the average diameter of the Tencel fibrillated fibers is 100nm to 2μm, and the length is 10mm to 50mm. More preferably, the average diameter is 100nm to 2μm, and the length is 3mm to 10mm.

[0064] Radiation sensitizer: 0.5 to 2.0 parts; the radiation sensitizer is a kind of vinyl bromide or vinyl chloride. When irradiated by electron beam, the radiation sensitizer will produce relatively active free radicals, which have an electron-absorbing induction effect and form a catalytic effect. Therefore, during the electron beam irradiation process, it can greatly increase the ability of the irradiated PET fiber and Tencel fibrillated fiber to absorb electrons, promote graft copolymerization between fibers, increase the graft copolymerization rate, reduce the porosity of the formed modified PET non-woven fabric, and at the same time reduce the electron beam irradiation amount to prevent excessive irradiation from damaging the fibers.

[0065] It is worth noting that the formula components of the modified PET non-woven fabric also include hydrophilic acrylic emulsion, which can improve the hydrophilicity of PET fibers and Tencel fibrillated fibers, thereby increasing the hydrophilic groups or hydrophilic materials on the periphery of PET fibers and Tencel fibrillated fibers, improving the grafting copolymerization efficiency of electron beam irradiation, and enabling better absorption of lithium salts. Preferably, the weight proportion of the hydrophilic acrylic emulsion is 1 to 5 parts, preferably 3 parts.

[0066] Among them, the formula of polymer electrolyte is:

[0067] PEO powder: 80 to 120 parts; PEO (polyethylene oxide) based solid polymer electrolyte has multiple oxygen atoms, which can coordinate with lithium ions, thereby effectively promoting the ion conduction pathway within the matrix; the molecular weight of PEO is 100,000 to 3 million, preferably 600,000 or 1 million.

[0068] Lithium salt: 10 to 20 parts; LiClO4, LiBF4, LiB 10 Cl 10 At least one of LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, LiSCN, LiC(CF3SO2)3, (CF3SO2)2NLi, (FSO2)2NLi, lithium chloroborane, lithium lower aliphatic carboxylate, lithium tetraphenylborate, and lithium imide can improve the release efficiency of the polymer electrolyte film in the battery for the positive electrode material, making the battery more stable and reliable.

[0069] Heat stabilizer: 5 to 20 parts; it is one or a mixture of sodium stearate, zinc stearate, and organic tin stabilizer to prevent PEO from melt extrusion and oxidation, aging, and yellowing during application.

[0070] Antioxidant: 0.5 to 1.0 parts; the antioxidant is one or a mixture of antioxidant 1010, antioxidant 1076 or antioxidant 168, which prevents or alleviates the decomposition of PEO powder during high-temperature plasticizing processing, and prevents chemical changes or aging caused by light and oxygen during use after molding, thereby reducing the service life.

[0071] Plasticizer: 5 to 20 parts; the plasticizer is paraffin oil, white mineral oil or glycerin; it has good compatibility with PEO and can be evenly mixed, reducing the glass transition temperature of PEO and the melt viscosity during molding processing, and improving the fluidity of PEO in the molten state.

[0072] Preferably, the formula of the modified PET nonwoven fabric is:

[0073] PET fiber: 100 parts;

[0074] Tencel fibrillated fiber: 15 parts;

[0075] Radiosensitizer: 1 part;

[0076] Preferably, the polymer electrolyte has a formula of:

[0077] PEO powder: 100 parts;

[0078] Lithium salt: 15 parts;

[0079] Heat stabilizer: 15 parts;

[0080] Antioxidant: 1 part;

[0081] Plasticizer: 15 parts.

[0082] This embodiment also provides a method for preparing a modified PET non-woven fabric matrix polymer electrolyte membrane, using the above-mentioned formula. In this embodiment, the preparation process of the modified PET non-woven fabric is specifically described with the formulas of different implementation methods in Table 1, and the preparation process of the polymer electrolyte and the preparation process of the modified PET non-woven fabric matrix polymer electrolyte membrane are carried out, and the effects of different weight portions of heat stabilizers and different weight portions of plasticizers on the performance of the modified PET non-woven fabric matrix polymer electrolyte membrane are verified.

[0083] To specifically illustrate the preparation process and performance characteristics of the implementation method, 100 parts of PET fiber, 15 parts of Tencel fibrillated fiber, 1 part of radiation sensitizer, and 3 parts of hydrophilic acrylic emulsion are selected to prepare a modified PET non-woven fabric, and the effects of different amounts of plasticizer in the polymer electrolyte formula on the extrusion temperature are analyzed and compared, and the visual effects of different amounts of heat stabilizers on the formed polymer electrolyte are analyzed and compared; to clearly illustrate the characteristics of the components, in Table 1, sodium stearate is selected as the heat stabilizer, antioxidant 1010 is selected as the antioxidant, and white mineral oil is selected as the plasticizer.

[0084] Table 1 Formula table of polymer electrolyte embodiment of the present invention

[0085]

[0086] Implementation 1:

[0087] See also Figure 1 , Figure 1 It is a schematic diagram of the process of preparing a polymer electrolyte membrane according to an embodiment of the present invention.

[0088] The preparation steps are:

[0089] Step S10: preparing a modified PET nonwoven fabric, comprising:

[0090] Step S110: Take deionized water, add PET fiber, Tencel fibrillated fiber and radiation sensitizer into the deionized water, and further add hydrophilic acrylic emulsion, and disperse by planetary stirring to form a first mixture; the mass concentration of the effective component in the first mixture is 6 to 10 ten thousandths, preferably 8 ten thousandths.

[0091] Step S120: Take a PE sealing bag, place the first mixture in the sealing bag, and introduce nitrogen until the nitrogen content in the sealing bag is 95% to 100% of the total gas content. Electron beam radiation curing is generally carried out in a high-purity nitrogen (or other inert gas) environment. The oxygen content usually needs to be less than 50ppm to 200ppm to avoid the occurrence of oxygen inhibition. Then seal it to form a first mixture sealing material bag.

[0092] Step S130: irradiating the first mixture sealing material bag with an electron beam, wherein the absorbed dose of the irradiation reaches 10KGy to 50KGy, preferably 30KGy. After irradiation, the first mixture forms an irradiated slurry, which is poured out and sequentially subjected to dehydration, forming, leveling, drying, and flattening processing, wherein the drying is performed by using a contact drying cylinder at 100°C to 120°C for 4 to 6 hours; the flattening is performed by using a roller at a temperature of 70°C to 90°C to flatten to 5μm to 100μm, to form a modified PET non-woven fabric with a porosity of 15% to 65%.

[0093] Step S20: preparing a polymer electrolyte membrane, comprising:

[0094] Step S210: adding a plasticizer, a lithium salt and an antioxidant to the PEO powder, and performing a second mixing and stirring to form a polymer electrolyte;

[0095] Step S220: extruding the polymer electrolyte onto the surface of the modified PET non-woven fabric, and performing compaction and cooling in sequence to form a modified PET non-woven fabric matrix polymer electrolyte membrane①.

[0096] Implementation 2:

[0097] The formula corresponding to Implementation Example 2 in Table 1 was selected, and the same preparation steps as Implementation Example 1 were used to prepare a modified PET non-woven fabric matrix polymer electrolyte membrane②.

[0098] Implementation 3:

[0099] The formula corresponding to Implementation Method 3 in Table 1 was selected, and the same preparation steps as Implementation Method 1 were adopted to prepare a modified PET non-woven fabric matrix polymer electrolyte membrane ③.

[0100] Implementation 4:

[0101] The formula corresponding to Implementation Example 4 in Table 1 was selected, and the same preparation steps as Implementation Example 1 were adopted to prepare a modified PET non-woven fabric matrix polymer electrolyte membrane④.

[0102] Implementation 5:

[0103] The formula corresponding to Implementation Example 5 in Table 1 was selected, and the same preparation steps as Implementation Example 1 were adopted to prepare a modified PET non-woven fabric matrix polymer electrolyte membrane ⑤.

[0104] In this embodiment, firstly, the effects of processing temperature during polymer electrolyte extrusion are analyzed by using Embodiment 1, Embodiment 2 and Embodiment 3 in Table 1 when the amount of plasticizer white mineral oil is successively increased, as shown in Table 2.

[0105] Table 2 Processing temperature of polymer electrolyte during extrusion

[0106]

[0107] Please refer to Table 1 again. The amount of plasticizer white mineral oil used in Implementation Example 1, Implementation Example 2 and Implementation Example 3 increases successively. It can be seen from Table 2 that as the content of plasticizer increases, the melting temperature of PEO decreases. When the amount of plasticizer is added to 15 parts, the optimal processing temperature has been reached. Continuing to add can no longer reduce the melt temperature of PEO. Adding an appropriate amount of plasticizer can appropriately reduce and stabilize the temperature during extrusion, and can make the extruded polymer electrolyte have a smooth, smooth and bright effect.

[0108] In this embodiment, the embodiment 2, embodiment 4 and embodiment 5 in Table 1 are further used to analyze that the dosage of the heat stabilizer sodium stearate is increased successively, and the extrusion temperature is selected to be the extrusion temperature corresponding to the embodiment 2 in Table 2, and the visual effect after extrusion of the polymer electrolyte is compared, as shown in Table 3.

[0109] Table 3 Comparison of visual effects of polymer electrolytes after extrusion

[0110]

[0111] Please refer to Table 1 again. The dosage of the heat stabilizer sodium stearate in Implementation Mode 2, Implementation Mode 4 and Implementation Mode 5 increases successively. It can be seen from Table 3 that adding a certain amount of heat stabilizer is beneficial to eliminating the yellowing phenomenon of the PEO melt at high temperature, but adding too much will lead to a rough surface, which is not conducive to subsequent extrusion processing, and the surface roughness is relatively large after compaction.

[0112] See also Figure 2 , Figure 2 FIG. 1 is a process flow chart for forming a roll-to-roll polymer electrolyte membrane according to an embodiment of the present invention.

[0113] When batch processing is required by the formula and preparation method of the embodiment of the present invention, a specific process method setting can be performed for step S220, as follows:

[0114] Take the first release film and the second release film, set the first release film layer on the lower surface of the modified PET non-woven fabric, extrude the polymer electrolyte to the upper surface of the modified PET non-woven fabric, set the second release film on the upper surface of the modified PET non-woven fabric, and perform compaction and cooling in sequence to form a polymer electrolyte membrane.

[0115] Wherein, the first release film or the second release film is one of a PEFE film, a TPFE film or a TPX film.

[0116] See also Figure 3 , Figure 3 The figure is a schematic diagram of the process flow of forming a roll-to-roll polymer electrolyte membrane according to an embodiment of the present invention.

[0117] This embodiment uses the formula of the modified PET non-woven fabric matrix polymer electrolyte membrane, and through the above-mentioned preparation method, roll-to-roll processing can be achieved during batch processing. Specifically, based on the film formation in S220, the roll-to-roll processing process steps are as follows:

[0118] S2210: The first release film and the second release film are both in roll form and are placed on an unwinder, and the modified PET non-woven fabric is made into a roll form and placed on the unwinder;

[0119] S2220: unwinding and laminating the first release film and the modified PET non-woven fabric to form a first PET film;

[0120] S2230: using a screw extruder to heat the polymer electrolyte to a molten state of 80° C. to 90° C., and extrude it onto one side of the modified PET non-woven fabric of the first PET film to form a second PET film; preferably, a single screw extruder is used for extrusion.

[0121] S2240: The second release film is laminated on the second PET film by unwinding, and is compacted by a pressing roller, cooled by a cooling roller, and then rolled up to form a rolled modified PET non-woven fabric matrix polymer electrolyte membrane.

[0122] The polymer electrolyte membrane in the prior art adopts a "sheet-to-sheet" processing method, generally using a doctor blade coating, slit coating, wire rod coating or casting process. The base membrane is first cut into a fixed size, and then the polymer electrolyte is made on the base membrane using a corresponding process. Obviously, the "sheet-to-sheet" processing efficiency is low, there are differences in the uniformity of the membranes processed in the entire batch, and the mechanical strength of the membranes is poor.

[0123] The roll-to-roll processing method adopted in the embodiment of the present invention, wherein the modified PET non-woven fabric forms an uncut continuous roll, and the polymer electrolyte is directly extruded onto the PET non-woven fabric through a screw extruder, compacted by a pressure roller and cooled by a cooling roller, the pressure roller applies a certain pressure to the polymer electrolyte, so that the film has higher mechanical strength. The overall process is based on a formula that can support roll-to-roll production, and the process flow is optimized to form a complete roll-to-roll processing process, which greatly improves the processing efficiency, the uniformity of the film formation, and the porosity of the film.

[0124] The first release film is provided to support the modified PET non-woven fabric and provide increased support strength for the polymer electrolyte to be extruded onto the modified PET non-woven fabric. The second release film is provided to isolate the polymer electrolyte from the pressing roller and the cooling roller during compaction and cooling processes, and to protect the manufactured polymer electrolyte membrane before it is used. When the polymer electrolyte membrane is used, the first release film and the second release film can be easily peeled off.

[0125] It is worth noting that the reason why the formula of this embodiment can form a roll-to-roll processing process in the preparation method is that the plasticizer in the formula has good compatibility with PEO and can be evenly mixed, thereby reducing the glass transition temperature of PEO and the melt viscosity during molding processing, and improving the fluidity of PEO in the molten state. Under normal circumstances, the viscosity of the PEO compound system is relatively large, and it is difficult to use an extruder for extrusion processing, and thus it is difficult to achieve roll-to-roll processing. After adding the plasticizer, the polymer electrolyte is formed with plasticizing and lubricating properties for extruder processing, thereby providing the necessary basic conditions for roll-to-roll processing; further, the plasticizer is selected from paraffin oil, white mineral oil or glycerin, and the amount of plasticizer is adjusted through experiments. When extruded from the extruder, the temperature of the PEO compound system is relatively high, and the plasticizer can be fully volatilized, and during the compaction process, the high-temperature pressure roller makes the plasticizer further volatilize, effectively preventing the plasticizer from remaining in the polymer electrolyte membrane.

[0126] The modified PET non-woven fabric matrix polymer electrolyte membrane formed by the above-mentioned roll-to-roll processing method is comprehensively analyzed. The modified PET non-woven fabric formula, polymer electrolyte formula and preparation method of this embodiment have advantages over the PET non-woven fabric and sheet-to-sheet preparation method of the prior art. The comparative analysis is shown in Table 4.

[0127] Table 4 Comparison of polymer electrolyte membrane prepared by prior art and embodiments of the present invention

[0128]

[0129] According to the formula and preparation method of Table 4, the existing technology membrane and the membrane of the embodiment of the present invention were prepared, and the tensile strength and ionic conductivity were tested at room temperature; the test results are shown in Table 5.

[0130] Table 5 Test results

[0131]

[0132] It can be seen from Tables 4 and 5 that the prior art membrane is a membrane that is made of polymer electrolyte on ordinary PET non-woven fabric in a sheet-to-sheet manner, and the tensile strength and ionic conductivity of the formed membrane are both low; while the membrane according to the embodiment of the present invention, on the one hand, uses a modified PET non-woven fabric containing Tencel fibrillated fibers and a radiation sensitizer formed by electron beam irradiation. When a hydrophilic acrylic emulsion is added, the fiber absorbs electron beam irradiation more efficiently, and the graft copolymerization rate under the same irradiation amount is higher; on the other hand, the formula of embodiment 4 of Table 1 of the embodiment of the present invention is used to form an extrudable polymer electrolyte with better performance, and then processed by the roll-to-roll preparation method of the embodiment of the present invention, after roller compaction and cooling by a cooling roller, the roller gives a certain pressure to the polymer electrolyte, so that the polymer electrolyte has better bonding performance with the modified PET non-woven fabric, forming a higher tensile strength and a smaller porosity, thereby forming a better modified PET non-woven fabric matrix polymer electrolyte membrane, and can effectively prevent lithium dendrites from penetrating and causing short circuit problems.

[0133] See also Figure 4 and Figure 5 , Figure 4 This is a scanning electron microscope image of a PET nonwoven fabric produced using the existing formula and production process; Figure 5 It is a scanning electron microscope image of the modified PET nonwoven fabric prepared by the embodiment of the present invention.

[0134] By observing the PET non-woven fabric produced by the formula and production process of the prior art and the modified PET non-woven fabric prepared by the embodiment of the present invention through a scanning electron microscope, it can be seen that the membrane of the prior art has a large porosity when it does not contain Tencel fibrillated fibers, does not add a radiation sensitizer, and does not use electron beam irradiation, which directly leads to the above-mentioned low tensile strength and ionic conductivity; while the modified PET non-woven fabric prepared by the embodiment of the present invention, by adding a radiation sensitizer and using an electron beam irradiation process, forms a membrane with a higher porosity, and has better tensile strength and ionic conductivity.

[0135] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A formula of a modified PET non-woven fabric matrix polymer electrolyte membrane, characterized in that: The formula of the modified PET nonwoven fabric and the weight proportions of each component are as follows: PET fiber: 80 to 120 parts; Tencel fibrillated fiber: 5 to 20 parts; Radiosensitizer: 0.5 to 2.0 parts; The formula of the polymer electrolyte and the weight proportions of each component are: PEO powder: 80 to 120 parts; Lithium salt: 10 to 20 parts; Heat stabilizer: 5 to 20 parts; Antioxidant: 0.5 to 1.0 parts; Plasticizer: 5 to 20 parts.

2. The formula of a modified PET nonwoven matrix polymer electrolyte membrane according to claim 1, characterized in that: The formula of the modified PET nonwoven fabric and the weight proportions of each component are as follows: PET fiber: 100 parts; Tencel fibrillated fiber: 15 parts; Radiosensitizer: 1 part; The formula of the polymer electrolyte and the weight proportions of each component are: PEO powder: 100 parts; Lithium salt: 15 parts; Heat stabilizer: 15 parts; Antioxidant: 1 part; Plasticizer: 15 parts.

3. The formula of a modified PET nonwoven matrix polymer electrolyte membrane according to claim 1 or 2, characterized in that: The radiation sensitizer is one of vinyl bromide and vinyl chloride.

4. The formula of a modified PET nonwoven matrix polymer electrolyte membrane according to claim 1 or 2, characterized in that: The modified PET nonwoven fabric also contains a hydrophilic acrylic emulsion in a weight ratio of 1 to 5 parts, preferably 3 parts.

5. The formula of a modified PET non-woven fabric matrix polymer electrolyte membrane according to claim 1 or 2, characterized in that: The heat stabilizer is one or a mixture of sodium stearate, zinc stearate or an organic tin stabilizer.

6. The formula of a modified PET nonwoven matrix polymer electrolyte membrane according to claim 1 or 2, characterized in that: The plasticizer is paraffin oil, white mineral oil or glycerin.

7. A method for preparing a modified PET non-woven fabric matrix polymer electrolyte membrane, characterized in that: The preparation method adopts the formulation according to any one of claims 1 to 6 and is prepared by the following steps: S10: preparing the modified PET nonwoven fabric; S110: taking deionized water, adding the PET fiber, the Tencel fibrillated fiber and the radiation sensitizer into the deionized water, and performing planetary stirring to disperse the fibers to form a first mixture; S120: taking a sealed bag, placing the first mixture in the sealed bag, introducing nitrogen, and then sealing the bag to form a first mixture sealed material bag; S130: irradiating the first mixture sealing material bag with an electron beam, the first mixture forms an irradiated slurry, pouring out the irradiated slurry, and sequentially performing dehydration, forming, leveling, drying, and flattening processes to form the modified PET non-woven fabric; S20: preparing the modified PET non-woven fabric matrix polymer electrolyte membrane: S210: adding the plasticizer, the heat stabilizer, the lithium salt and the antioxidant to the PEO powder, mixing and stirring to form the polymer electrolyte; S220: Extruding the polymer electrolyte onto the surface of the modified PET non-woven fabric, and performing compaction and cooling in sequence to form the modified PET non-woven fabric matrix polymer electrolyte membrane.

8. The method for preparing a modified PET non-woven fabric matrix polymer electrolyte membrane according to claim 7, characterized in that: The absorbed dose of the irradiation is 10 KGy to 50 KGy.

9. The method for preparing a modified PET nonwoven fabric matrix polymer electrolyte membrane according to claim 7, characterized in that: The processing steps of S220 are: taking a first release film and a second release film, setting the first release film on the lower surface of the modified PET non-woven fabric, extruding the polymer electrolyte to the upper surface of the modified PET non-woven fabric, setting the second release film on the upper surface of the modified PET non-woven fabric, and sequentially compacting and cooling to form the polymer electrolyte membrane.

10. The method for preparing a polymer electrolyte membrane with a modified PET non-woven fabric substrate according to claim 9, characterized in that: The processing steps of S220 are as follows: S2210: The first release film and the second release film are both in roll form and are placed on an unwinder, and the modified PET non-woven fabric is rolled and placed on the unwinder; S2220: unwinding and laminating the first release film and the modified PET non-woven fabric to form a first PET film; S2230: using a screw extruder to heat the polymer electrolyte to a molten state, and extruding the polymer electrolyte to one side of the modified PET non-woven fabric of the first PET film to form a second PET film; S2240: The second release film is laminated on the second PET film by unwinding, and is compacted by a pressing roller, cooled by a cooling roller, and then rolled up to form the modified PET non-woven fabric matrix polymer electrolyte membrane in a roll.

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