Solid polymer electrolyte diaphragm as well as preparation method and application thereof

Abstract

The invention discloses a solid polymer electrolyte diaphragm as well as a preparation method and application thereof, and the solid polymer electrolyte diaphragm is formed by mixing a polymer monomer of a formula 1 and an electrolyte, then carrying out polymerization reaction and curing to form a film, and the solid polymer electrolyte diaphragm is # imgabs0. The adopted preparation method is mild in condition and simple to operate, the film is directly formed on the surface of a pole piece through an ultraviolet irradiation polymerization process, the interface performance of a battery pack can be improved, the interface resistance between electrodes is greatly reduced, the room-temperature ionic conductivity of the prepared solid electrolyte diaphragm reaches up to (2.3 * 10 <-4 > S / cm, 25 DEG C), and the solid electrolyte diaphragm is nonflammable and has a great application prospect.

Description

Technical Field

[0001] The invention belongs to the field of batteries, and in particular relates to a solid polymer electrolyte diaphragm and a preparation method and application thereof. Background Art

[0002] As one of the eternal driving forces for sustainable social development, energy has always received widespread attention from the scientific community. Among energy conversion and storage systems, electrochemical energy storage is one of the most convenient and efficient systems. In addition to traditional lithium-ion batteries, new energy storage devices such as lithium-sulfur batteries, sodium-ion batteries and supercapacitors are also developing rapidly. Electrochemical energy storage devices are composed of four parts, namely positive electrode, negative electrode, diaphragm and electrolyte. Among them, the electrolyte plays the role of conducting ions and isolating electrons, and is an indispensable part of the entire device. However, the electrolytes currently used usually contain flammable organic solvents, which makes energy storage devices have certain safety hazards. Therefore, developing highly safe solid electrolytes to replace liquid electrolytes is an important way to solve the safety problems of high energy storage devices.

[0003] Solid electrolytes exist in solid form, replacing the original electrolyte and diaphragm, and have the function of conducting ions and isolating electrons. According to the composition classification, they can be divided into three categories: polymer solid electrolytes, inorganic solid electrolytes, and polymer / inorganic composite solid electrolytes. Among them, polymer electrolytes have become the subject of extensive research due to their high safety, viscoelasticity, and good interfacial compatibility. However, their ionic conductivity at room temperature is still low (10 -6 S / cm), and compared with electrolytes, solid electrolytes have interface problems, which greatly limits the application of solid electrolytes. Therefore, improving the interface problems and ionic conductivity of solid electrolytes has become an urgent need. Summary of the invention

[0004] The purpose of the present invention is to provide a solid polymer electrolyte membrane prepared by ultraviolet light polymerization under mild conditions and simple operation to address the interface problems of existing solid electrolyte products, and to provide a preparation method and application of the above-mentioned solid polymer electrolyte membrane.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme: a solid polymer electrolyte membrane, wherein the solid polymer electrolyte membrane is formed by mixing a polymer monomer of Formula 1 with an electrolyte, and then curing the mixture through a polymerization reaction to form a film,

[0006]

[0007] Further, in the monomer of formula 1, n1, n2, n3 are 1, 2, 3, 4, or 5, R is formula 2, formula 3, or formula 4; R1 is an alkyl group or an aromatic group;

[0008]

[0009] Furthermore, the electrolyte is a DOL / DME solution of LiPF6, LiTFSI, NaPF6, NaTFSI, or an EC / DMC solution of LiPF6, LiTFSI, NaPF6, NaTFSI; the concentration of the electrolyte is 0.1-6.0 mol / L, and the weight ratio of the monomer to the electrolyte is 1:0.5-7.0.

[0010] Furthermore, the weight average molecular weight of the solid polymer electrolyte membrane is 3w to 50w.

[0011] Furthermore, the polymerization reaction is carried out under ultraviolet light irradiation, the ultraviolet light wavelength is 20 to 370 nm, and the irradiation time is 1 second to 3 hours.

[0012] A method for preparing the above-mentioned solid polymer electrolyte membrane comprises the following steps:

[0013] (1) mixing the polymer monomer and the electrolyte, and adding an initiator;

[0014] (2) The mixed slurry is coated on a substrate, and a polymerization reaction is carried out under light conditions to cure the mixed slurry, thereby forming a solid polymer electrolyte membrane in situ.

[0015] Furthermore, the mixing method in step (1) is mechanical stirring or magnetic stirring, and the stirring rate is 200 to 1800 r / min.

[0016] Furthermore, the initiator of step (1) is 2-hydroxy-2-methyl-1-phenyl-1-propanone or benzil dimethyl ether, and the added ratio of the initiator is 0.1% to 10% of the mass of the polymer monomer.

[0017] Furthermore, the substrate in step (2) is NCM111, NCM532, NCM811, LiFePO4 electrode, NaFePO4 electrode, Prussian blue, PET film, glass or lithium sheet; the coating operation method is scraper coating or natural flow, the scraper slit width is 10 to 70 μm when scraper coating is used, and the operation inclination angle is 10° to 40° when natural flow is used.

[0018] An application of the above-mentioned solid polymer electrolyte membrane in a battery, wherein the polymer monomer of Formula 1 is mixed with an electrolyte, and the mixed slurry is coated on a substrate for polymerization reaction and curing.

[0019]

[0020] When the substrate is a lithium sheet, Prussian blue, NCM111, NCM532, NCM811, LiFePO4 pole piece or NaFePO4 pole piece, the solidified solid polymer electrolyte diaphragm and the substrate are used together as the membrane electrode of the battery. When the substrate is a PET film or glass, the solidified solid polymer electrolyte diaphragm is peeled off and used as the diaphragm of the battery.

[0021] The beneficial effects of the present invention are as follows: the solid polymer electrolyte membrane provided by the present invention has a mild preparation method and is simple to operate. The membrane is directly formed on the surface of the electrode by ultraviolet light polymerization, which greatly reduces the interface resistance between the electrodes. The room temperature ionic conductivity of the solid electrolyte membrane prepared by the present invention is as high as (2.3*10 -4 S / cm, 25℃), and is non-flammable, and has great application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the nuclear magnetic resonance of the polymer electrolyte membrane of Example 1 1 HNMR spectrum.

[0023] Figure 2 This is the GPC spectrum of the polymer electrolyte membrane of Example 1.

[0024] Figure 3 is the ionic conductivity of the polymer electrolyte membrane of Example 1 at different temperatures.

[0025] Figure 4 This is the charging and discharging performance of the polymer electrolyte membrane assembly of Example 2.

[0026] Figure 5 This is the AC impedance test diagram of the membrane electrode in Example 2. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiment of the present application will be clearly and completely described below in combination with the embodiment of the present application. Obviously, the described embodiment is only a part of the embodiment of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present application.

[0028] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or apparatuses.

[0029] Example 1

[0030] A solid polymer electrolyte membrane and a preparation method and application thereof, the steps are as follows:

[0031] 1. Take a 50 mL single-necked flask and replace it with argon three times.

[0032] 2. Under argon protection, add 30 mL of 1 mol / L LiTFSI in DOL / DME solution into the flask.

[0033] 3. Under argon protection, weigh 5.0 g (0.019 mol) of 3-(diacrylamino)propane-1-trifluoromethylsulfonimide and add it into a 50 mL single-necked flask.

[0034] 4. Add a magnet to the flask, set the speed to 500r / min, and stir magnetically at 30°C for 3 hours until the solution is completely dissolved and becomes a colorless, transparent or slightly yellowish transparent solution.

[0035] 5. Use a rubber-tipped dropper to pipette 3 mL of the solution and drop it onto a 25 μm polyurethane (PET) film.

[0036] 6. Set the scraper gap width to 20μm and apply the slurry evenly.

[0037] 7. Place the coated PET under a UV lamp, set the UV wavelength to 254nm, and irradiate for 2 hours to solidify it.

[0038] 8. After curing, a transparent film appears on the PET substrate, which is slowly peeled off to obtain a polymer electrolyte membrane with a thickness of 8 μm.

[0039] 9. The polymer electrolyte film was made into a blocking electrode and the ionic conductivity was tested. The results showed that the ionic conductivity was 2.3*10 at 25°C. -4 S / cm, see Figure 3 .

[0040] The NMR spectrum is consistent with the monomer structure ( Figure 1 ), 1H NMR: δ6.08(=CH-,2H), 5.77(=CH2,4H), 3.98(N-CH2,4H), 3.45(-CH2-,2H), 3.06(-CH3,3H), 3.00(-CH2-,2H), 2.29(-CH2-,2H).

[0041] GPC results showed that the weight average molecular weight of the polymer after photopolymerization was 72867 ( Figure 2 ), the polymerization reaction occurs. The ionic conductivity of the polymer electrolyte membrane was tested by AC impedance method, and its ionic conductivity at room temperature (25°C) was 2.3*10-4 S / cm( Figure 3 ), compared with the ionic conductivity of conventional polymer electrolyte membranes (generally 10 -6 S / cm) has been greatly improved.

[0042] Example 2

[0043] A solid polymer electrolyte membrane and a preparation method and application thereof, the steps are as follows:

[0044] 1. Take a 50 mL single-necked flask and replace it with argon three times.

[0045] 2. Under argon protection, add 20mL of 1mol / L LiF6PO4 EC / DMC solution into the flask.

[0046] 3. Under argon protection, weigh 4.0 g (0.016 mol) of 3-(divinylamino)propane-1-sulfonic acid and add it into a 50 mL single-necked flask.

[0047] 4. Add a magnet to the flask, set the speed to 1000r / min, and stir magnetically at 30°C for 2.5 hours until the solution is completely dissolved and becomes a colorless, transparent or slightly yellowish transparent solution.

[0048] 5. Use a rubber-tipped dropper to pipette 4 mL of the solution and drop it onto a 55 μm commercial NCM111 electrode.

[0049] 6. Set the scraper gap width to 25μm and apply the slurry evenly.

[0050] 7. Place the scraped commercial NCM111 electrode under a UV lamp, set the UV wavelength to 360nm, and irradiate for 50s to cure it.

[0051] 8. After curing, a transparent film appears on NCM111 to obtain a polymer electrolyte membrane electrode with a total thickness of 60 μm.

[0052] 9. The polymer electrolyte membrane electrode was made into a soft pack battery and the cycle performance was tested ( Figure 4 ). It shows that at 25°C, after 100 cycles, the coulombic efficiency is close to 100%; and it has a certain rate performance and can be charged and discharged at a high rate of 5C, which has practical prospects.

[0053] 10. The NM111 electrode from the same batch and the commercial PP film were made into blocking electrodes and the AC impedance was tested ( Figure 5 ); The comparison shows that the membrane electrode impedance is smaller, indicating that the polymer electrolyte membrane electrode has improved the interface resistance to a certain extent.

[0054] The above description is only the preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A solid polymer electrolyte membrane, characterized in that: The solid polymer electrolyte membrane is formed by mixing the polymer monomer of Formula 1 with the electrolyte, and then curing the mixture through polymerization to form a film.

2. The solid polymer electrolyte membrane according to claim 1, characterized in that: In the monomer of formula 1, n1, n2, n3 are 1, 2, 3, 4 or 5, R is of formula 2, formula 3 or formula 4; R1 is an alkyl group or an aromatic group; 3. The solid polymer electrolyte membrane according to claim 1, characterized in that: The electrolyte is a DOL / DME solution of LiPF6, LiTFSI, NaPF6, or NaTFSI, or an EC / DMC solution of LiPF6, LiTFSI, NaPF6, or NaTFSI; the concentration of the electrolyte is 0.1 to 6.0 mol / L, and the weight ratio of the monomer to the electrolyte is 1:0.5 to 7.

0.

4. The solid polymer electrolyte membrane according to claim 1, characterized in that: The weight average molecular weight of the solid polymer electrolyte membrane is 3w-50w.

5. The solid polymer electrolyte membrane according to claim 1, characterized in that: The polymerization reaction is carried out under ultraviolet light irradiation, the wavelength of the ultraviolet light is 20 to 370 nm, and the irradiation time is 1 second to 3 hours.

6. A method for preparing a solid polymer electrolyte membrane according to any one of claims 1 to 5, characterized in that The following steps are involved: (1) mixing the polymer monomer and the electrolyte, and adding an initiator; (2) The mixed slurry is coated on a substrate, and a polymerization reaction is carried out under light conditions to cure the mixed slurry, thereby forming a solid polymer electrolyte membrane in situ.

7. The preparation method according to claim 6, characterized in that: The mixing method in step (1) is mechanical stirring or magnetic stirring, and the stirring rate is 200 to 1800 r / min.

8. The preparation method according to claim 6, characterized in that: The initiator in step (1) is 2-hydroxy-2-methyl-1-phenyl-1-propanone or benzil dimethyl ether, and the initiator addition ratio is 0.1% to 10% of the mass of the polymer monomer.

9. The preparation method according to claim 6, characterized in that: The substrate in step (2) is NCM111, NCM532, NCM811, LiFePO4 pole piece, NaFePO4 pole piece, Prussian blue, PET film, glass or lithium sheet; the coating operation method is blade coating or casting, and the blade slit width is 10 to 70 μm when blade coating is used.

10. Use of the solid polymer electrolyte membrane according to any one of claims 1 to 5 in a battery, characterized in that: After the polymer monomer of Formula 1 is mixed with the electrolyte, the mixed slurry is coated on the substrate for polymerization reaction and curing. When the substrate is a lithium sheet, Prussian blue, NCM111, NCM532, NCM811, LiFePO4 pole piece or NaFePO4 pole piece, the solidified solid polymer electrolyte diaphragm and the substrate are used together as the membrane electrode of the battery. When the substrate is a PET film or glass, the solidified solid polymer electrolyte diaphragm is peeled off and used as the diaphragm of the battery.

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