Lithium battery polymer solid electrolyte membrane capable of rapidly polymerizing at room temperature as well as preparation method and application of lithium battery polymer solid electrolyte membrane

Abstract

The invention discloses a lithium battery polymer solid electrolyte membrane capable of rapidly polymerizing at room temperature as well as a preparation method and application thereof, and belongs to the field of polymer electrolyte. The preparation method of the lithium battery polymer solid electrolyte membrane provided by the invention comprises the following steps: uniformly mixing polyethylene glycol methyl ether methacrylate and acrylonitrile according to a preset proportion to obtain a blended solution; sequentially adding lithium bis (trifluoromethanesulfonimide), divinylbenzene and benzoin diethyl ether into the blended solution, and uniformly mixing to obtain a precursor solution; and coating the precursor solution, and carrying out ultraviolet curing to obtain the lithium battery polymer solid electrolyte membrane. According to the lithium battery polymer solid electrolyte membrane provided by the invention, the voltage withstanding characteristic and the high ion conduction performance of the polymer electrolyte can be simultaneously improved, and the lithium battery polymer solid electrolyte membrane has a great gain on battery circulation and stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer electrolytes, and particularly relates to a polymer solid electrolyte membrane for rapid polymerization at room temperature and a preparation method thereof. Background Art

[0002] With the continuous progress of science and technology, wearable and portable devices have provided convenience for people's daily lives. Therefore, the demand for high-energy-density and environmentally friendly energy storage devices has been greatly increased. Lithium-ion batteries (LIBs) are considered promising energy storage batteries due to their low mass, high energy density, and good cycle stability. Currently, commercially available LIBs use carbonate and organic ether-based electrolytes. However, due to their poor antioxidant properties, strong flammability, and high reactivity with electrode materials such as metallic lithium, silicon, carbon materials, and nickel ternary-based oxides, there are serious safety problems, which hinder their further large-scale application. Considering the above challenges, researchers have focused on the field of solid electrolytes for rechargeable batteries. Compared with organic liquid electrolytes, solid electrolytes have many obvious advantages: (1) Solid electrolytes do not have fluidity characteristics, are not easily combustible, and have a relatively high thermal stability compared to similar electrolytes, significantly improving the safety of lithium batteries; (2) Solid electrolytes, especially polymer electrolytes, due to their unique physical properties, are easy to bend and stretch, and have a small volume, which can significantly improve the volume energy density of lithium batteries; (3) Solid electrolytes have good compatibility with lithium-ion battery systems. Compared with liquid electrolytes, solid electrolytes are more stable in a high-oxidation environment and can also effectively reduce the decomposition of electrodes in air. However, solid polymer electrolytes (SPE) usually have poor mechanical strength and low electrochemical stability. In addition, the crystalline regions of the polymer matrix are also not conducive to the gelation process and ion transport. Therefore, a new type of polymer electrolyte with improved electrochemical and physical properties is needed to realize its practical application.

[0003] In recent years, a great deal of effort has been made to solve the above problems. Different polymer matrices with polar functional groups have been considered for the preparation of SPEs, such as poly(ethylene oxide) (PEO), poly(vinyl alcohol) (PVA), poly(methyl methacrylate) (PMMA), polyacrylonitrile (PAN), poly(vinylidene difluoride) (PVDF), etc. Among them, PAN has excellent solvent retention ability, good film-forming ability, biodegradability and low toxicity, which is very attractive for the preparation of solid polymer electrolytes; however, the dissociation ability of pure PAN for lithium salts is poor and it cannot be used alone as a polymer matrix. To improve these properties of the PAN-based polymer matrix, methods such as blending with other polymers and inserting ceramic fillers are usually adopted. However, the preparation of these polymers is based on the solution casting method. One disadvantage of solution casting is that its mechanical properties (such as tensile resistance) are usually worse than those of cross-linked polymers, and the handling of hazardous chemical solvents is also a troublesome problem. Therefore, introducing chemical cross-linking bonds into the polymer structure is considered an effective method to improve the mechanical properties, thermal stability and dimensional stability of SPEs, but in current research, the chemical cross-linking of PAN and other polymers has rarely been studied. Summary of the Invention

[0004] In order to solve the problems that when using pure polyacrylonitrile to prepare solid polymer electrolytes, the dissociation ability of PAN for lithium salts is poor, and the mechanical properties of the film prepared by the solution casting method are poor, the present invention provides a lithium battery polymer solid electrolyte film with rapid polymerization at room temperature and a preparation method thereof. The present invention proposes a cross-linking synthesis strategy using poly(ethylene glycol) monomethyl ether acrylate (PEGMEMA) and acrylonitrile (AN); AN has excellent mechanical support performance and certain lithium salt dissociation ability, and the EO (ethylene oxide) group of PEGMEMA can significantly promote the dissociation of lithium salts. Then, through the appropriate reaction ratio of PEGMEMA and AN, a lithium battery polymer solid electrolyte film with excellent mechanical and electrical properties can be obtained.

[0005] To achieve the above object, the technical solution adopted by the present invention is: The present invention provides a preparation method of a lithium battery polymer solid electrolyte film with rapid polymerization at room temperature, including: Mix polyethylene glycol methyl ether methacrylate and acrylonitrile evenly to obtain a blend solution; Add lithium bis(trifluoromethanesulfonyl)imide, divinylbenzene and benzoin ethyl ether to the blend solution and mix evenly to obtain a precursor solution; Perform a coating treatment on the precursor solution and perform an ultraviolet curing treatment on the precursor solution to obtain a lithium battery polymer solid electrolyte membrane.

[0006] The step of mixing polyethylene glycol methyl ether methacrylate and acrylonitrile evenly to obtain a blend solution is specifically as follows: The mass ratio of polyethylene glycol methyl ether methacrylate to acrylonitrile is (3-7):(7-3); Magnetically stir polyethylene glycol methyl ether methacrylate and acrylonitrile in an ice-water bath at a temperature of 0-5°C for 5-10 min to obtain a blend solution.

[0007] The addition amount of lithium bis(trifluoromethanesulfonyl)imide is 39%-41% of the total mass of polyethylene glycol methyl ether methacrylate and acrylonitrile.

[0008] The addition amount of divinylbenzene is 4.9%-5.1% of the total mass of polyethylene glycol methyl ether methacrylate and acrylonitrile; the addition amount of benzoin ethyl ether is 0.9%-1.1% of the total mass of polyethylene glycol methyl ether methacrylate and acrylonitrile.

[0009] The step of adding lithium bis(trifluoromethanesulfonyl)imide, divinylbenzene and benzoin ethyl ether to the blend solution in sequence and mixing evenly to obtain a precursor solution, wherein the conditions for mixing evenly are: in an inert atmosphere, magnetically stir in an ice-water bath at a temperature of 0-5°C for 5-10 min.

[0010] The step of performing a coating treatment on the precursor solution is specifically as follows: Coat the precursor solution on the surface of the first film-forming mold, place copper wires at the four corners of the first film-forming mold respectively, and then cover the second film-forming mold on the upper layer of the copper wires to spread the precursor solution evenly; The length of the copper wire is 2-3 cm, the diameter is 25-35 μm, the misalignment angle between the first film-forming mold and the second film-forming mold is 30-50°, and the temperature during the coating process is 22-28°C.

[0011] The conditions for the ultraviolet curing treatment are specifically as follows: The ultraviolet light wavelength is 200-260 μm, and the illumination time is 18-22 min.

[0012] The lithium battery polymer solid electrolyte membrane is stored in an argon environment, and the water in the argon environment is <0.1 ppm and the oxygen is <0.1 ppm.

[0013] The present invention also provides a lithium battery polymer solid electrolyte membrane that rapidly polymerizes at room temperature, which is prepared according to the above-mentioned preparation method of the lithium battery polymer solid electrolyte membrane that rapidly polymerizes at room temperature. The lithium battery polymer solid electrolyte membrane includes a polymer matrix and a lithium salt. The polymer matrix is obtained by polymerizing polyethylene glycol methyl ether methacrylate and acrylonitrile, and the structural formula of the polymer matrix is:

[0014] In the formula, x and y represent the mass ratio of polyethylene glycol methyl ether methacrylate and acrylonitrile, and x + y = 1.

[0015] The present invention also provides the application of the above-mentioned lithium battery polymer solid electrolyte membrane that rapidly polymerizes at room temperature. The lithium battery polymer solid electrolyte membrane is used for lithium ion batteries.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The lithium battery polymer solid electrolyte membrane provided by the present invention is a lithium battery polymer solid electrolyte membrane of PEGMEMA-PAN (Poly(ethylene glycol) monomethyl ether acrylate-Polyacrylonitrile) synthesized by rapid cross-linking of AN and PEGMEMA under ultraviolet light. Among them, AN has good film-forming properties, and the nitrile bond of AN can also promote the dissociation of lithium salt. The EO group of PEGMEMA significantly improves the dissociation efficiency of lithium salt. In addition, this cross-linking polymerization can reduce the crystallization degree of monomer polymers, and can simultaneously improve the pressure resistance characteristics and high ionic conductivity of polymer electrolytes. At the same time, compared with the film-forming time of more than 24 hours in the traditional solution casting film-forming method, the rapid polymerization film-forming method provided by the present invention has a simple and easy preparation process, can significantly shorten the film-forming time, and does not require the use of organic solvents during the preparation process, thus avoiding the influence of organic solvents on battery performance.

[0017] The lithium battery polymer solid electrolyte membrane prepared by the present invention has a thickness of 25-35 μm, an ionic conductivity of 1.3×10 -4 cm -1 at room temperature, and an electrochemical window of 4.5 V. The lithium deposition / stripping curve proves that the interface compatibility between the lithium battery polymer solid electrolyte membrane and the electrode is good, can effectively inhibit the growth of lithium dendrites, and shows excellent cycle stability. When it is applied to a lithium iron phosphate solid battery, after cycling at different rates, when the current rapidly decreases to 0.1 C, the discharge capacity can still recover to 154 mA cm -2This is sufficient to prove that the new polymer matrix has a great improvement in battery cycling and stability. In addition, the lithium battery polymer solid electrolyte membrane of the present invention does not contain organic solvents, thus greatly improving the safety performance of lithium batteries, demonstrating its strong application potential in lithium batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 It is the Fourier infrared spectrum diagram of the lithium battery polymer solid electrolyte membrane prepared in Example 1 of the present invention; Figure 2 It is the symmetric stability test diagram of the lithium battery polymer solid electrolyte membranes prepared in Example 1 and Comparative Example 1 of the present invention; Figure 3 It is the SEM image of the lithium anode after the lithium battery polymer solid electrolyte membrane repeats the stripping / deposition process; where (a) is the scanning electron microscope (SEM) image of the lithium anode after the lithium battery polymer solid electrolyte membrane prepared in Example 1 repeats the stripping / deposition process; (b) is the SEM image of the lithium anode after the lithium battery polymer solid electrolyte membrane prepared in Comparative Example 1 repeats the stripping / deposition process. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] In order to make the technical problems to be solved, technical solutions and beneficial effects of the present application more clear and understandable, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0021] In the present application, the term "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after.

[0022] In this application, "at least one" means one or more, and "a plurality" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single item(s) or plural item(s). For example, "at least one of a, b, or c", or "at least one of a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0023] It should be understood that in various embodiments of this application, the magnitude of the serial numbers of the above - mentioned processes does not imply the order of execution. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of this application.

[0024] The terms used in the embodiments of this application are only for the purpose of describing specific embodiments, and are not intended to limit this application. The singular forms "a", "the", and "said" used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0025] The weight of the relevant components mentioned in the specification of the embodiments of this application not only can refer to the specific content of each component, but also can represent the proportional relationship of the weights between the components. Therefore, as long as the content of the relevant components in the specification of the embodiments of this application is scaled up or down proportionally, it is within the scope disclosed in the specification of the embodiments of this application. Specifically, the mass mentioned in the specification of the embodiments of this application can be mass units well - known in the chemical field such as μg, mg, g, kg, etc.

[0026] The present invention also provides a method for preparing a lithium - battery polymer solid - electrolyte membrane with rapid polymerization at room temperature, including: uniformly mixing polyethylene glycol methyl ether methacrylate and acrylonitrile to obtain a blend solution; sequentially adding lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), divinylbenzene (DVB), and benzoin ethyl ether to the blend solution and mixing uniformly to obtain a precursor solution; performing a coating treatment on the precursor solution, and performing an ultraviolet - light curing treatment on the precursor solution to obtain a lithium - battery polymer solid - electrolyte membrane, denoted as PEGMEMA x -PAN y , where x and y represent the mass ratio of polyethylene glycol methyl ether methacrylate and acrylonitrile, and x + y = 1.

[0027] In some embodiments, the mass ratio of polyethylene glycol methyl ether methacrylate to acrylonitrile is (3 - 7):(7 - 3); controlling the reaction ratio of PEGMEMA and AN within this range can prepare a lithium battery polymer solid electrolyte membrane with high flexibility and good mechanical strength.

[0028] In some embodiments, a blend solution of polyethylene glycol methyl ether methacrylate and acrylonitrile is magnetically stirred in an ice - water bath at a temperature of 0 - 5 °C for 5 - 10 min; lithium bis(trifluoromethanesulfonyl)imide, divinylbenzene, and benzoin ethyl ether are added to the blend solution, and it is magnetically stirred in an ice - water bath at a temperature of 0 - 5 °C in an inert atmosphere for 5 - 10 min to obtain a precursor solution. By controlling the reaction temperature in the ice - water bath, problems such as too fast reaction and excessive cross - linking of the polymer caused by too high temperature are prevented, and side reactions are reduced.

[0029] In some embodiments, the addition amount of lithium bis(trifluoromethanesulfonyl)imide is 39% - 41% of the total mass of polyethylene glycol methyl ether methacrylate and acrylonitrile. As a lithium salt, LiTFSI has excellent electrical conductivity and stable chemical properties. An appropriate amount of LiTFSI can optimize battery performance. Excessive LiTFSI may cause crystallization or aggregation of excess lithium salt in the electrolyte membrane, reducing the ionic conductivity of the electrolyte membrane and at the same time reducing the mechanical strength of the electrolyte membrane; too little LiTFSI will lead to problems such as reduced conductivity and unstable battery performance.

[0030] In some embodiments, the addition amount of divinylbenzene is 4.9% - 5.1% of the total mass of polyethylene glycol methyl ether methacrylate and acrylonitrile. As a cross - linker, divinylbenzene needs to ensure good mechanical and electrical conductivity of the electrolyte membrane while avoiding excess or deficiency. Excessive addition of divinylbenzene will increase the brittleness of the membrane and limit the movement of ions in the electrolyte membrane, resulting in reduced ionic conductivity; a small amount of addition will cause insufficient cross - linking degree, resulting in reduced mechanical properties and heat resistance of the electrolyte membrane.

[0031] In some embodiments, the precursor solution is cast on the surface of the first film - forming mold, copper wires are placed at the four corners of the first film - forming mold, and then the second film - forming mold is covered on the upper layer of the copper wires to evenly spread the precursor solution; the length of the copper wire is 2 - 3 cm, the diameter is 25 - 35 μm, the misalignment angle between the first film - forming mold and the second film - forming mold is 30 - 50°, and the temperature during the film - coating process is 22 - 28 °C. In this preparation method, placing copper wires in the middle of the film - forming mold helps to maintain the uniformity of the film - forming thickness. If a material with poor stiffness is used, the weight of the mold may affect the thickness uniformity of the film at different positions.

[0032] In some embodiments, the addition amount of benzoin ethyl ether is 0.9% - 1.1% of the total mass of polyethylene glycol methyl ether methacrylate and acrylonitrile. Benzoin ethyl ether acts as a photoinitiator during the preparation process and can release free radicals under ultraviolet light irradiation. Under the condition of ultraviolet light irradiation, it initiates a photoreaction to help form a cross-linked network structure in the lithium battery polymer solid electrolyte membrane. When ultraviolet light curing is carried out, the wavelength of the ultraviolet light is 200 - 260 μm, and the irradiation time is 18 - 22 min. By selecting appropriate ultraviolet light wavelength and reaction time, the reaction efficiency can be improved and the occurrence of side reactions can be reduced.

[0033] In some embodiments, the lithium battery polymer solid electrolyte membrane is stored in an argon environment, and the water content in the argon environment is < 0.1 ppm and the oxygen content is < 0.1 ppm. Storing the prepared lithium battery polymer solid electrolyte membrane in such an environment helps to protect the lithium battery polymer solid electrolyte membrane from the influence of moisture, oxygen, etc., so as to maintain its stable performance and extend its service life.

[0034] The lithium battery polymer solid electrolyte membrane with rapid polymerization at room temperature provided by the embodiments of the present invention is prepared by the preparation method of the lithium battery polymer solid electrolyte membrane with rapid polymerization at room temperature. The lithium battery polymer solid electrolyte membrane includes a lithium polymer matrix and a lithium salt. The polymer matrix is synthesized by cross-linking of AN and PEGMEMA, and the structural formula of the polymer matrix is:

[0035] In the formula, x and y represent the mass ratio of polyethylene glycol methyl ether methacrylate and acrylonitrile, and x + y = 1.

[0036] Through specific structural design, the present invention cross-links and polymerizes a nitrile bond with good film-forming performance and an EO group with good dissociation performance and a flexible chain segment through photoinitiation. This method promotes the dissociation and migration of lithium ions and also improves the safety performance of the battery to inhibit lithium dendrites, which plays a beneficial role in battery cycling and stability.

[0037] The embodiments of the present invention also provide that the lithium battery polymer solid electrolyte membrane is used in a lithium ion battery, which has a great beneficial effect on the battery cycling and stability of the lithium ion battery.

[0038] In the following embodiments, unless otherwise specified, all materials used can be obtained through ordinary channels; the test methods adopted are conventional methods in the art.

[0039] Example 1 The specific steps for preparing the lithium battery polymer solid electrolyte membrane (PEGMEMA0.5 - PAN0.5) in this example are as follows: (1) Weigh 5.00 g of PEGMEMA and 5.00 g of AN and add them to a beaker. Magnetically stir for 5 min in an ice-water bath at 0 °C to obtain a clear and transparent blend solution; (2) Sequentially add 4.00 g of LiTFSI, 0.50 g of DVB, and 0.1 g of benzoin ethyl ether to the blend solution obtained in step (1). Under a nitrogen atmosphere, magnetically stir for 5 min in an ice-water bath at 0 °C to obtain a precursor solution; (3) Cast the precursor solution obtained in step (2) onto the surface of a first glass mold. Place a section of copper wire at each of the four corners of the first glass mold. The length of the copper wire is 2 cm and the diameter is 30 μm. Then cover the upper layer of the copper wire with a second glass mold. The misalignment angle between the first glass mold and the second glass mold is 30°, so that the precursor solution spreads evenly between the glass molds to the required thickness. The temperature during the entire film coating process is 22 - 23 °C; (4) Horizontally place the glass mold loaded with the precursor solution obtained in step (3) on a test bench. Irradiate it with ultraviolet light (UV) with a wavelength of 250 μm for 20 min to initiate a polymerization reaction. After curing, a lithium battery polymer solid electrolyte membrane is obtained, denoted as PEGMEMA0.5 - PAN0.5.

[0040] Store PEGMEMA0.5 - PAN0.5 in a glove box filled with argon (water < 0.1 ppm, oxygen < 0.1 ppm).

[0041] Assemble the PEGMEMA0.5 - PAN0.5 prepared in Example 1 with a positive electrode (lithium iron phosphate) and a negative electrode (lithium metal sheet) into a 2025 - type button battery for performance testing: The conductivity measured at room temperature is 1.3×10 -4 S / cm -1 . To detect the application of the PEGMEMA0.5 - PAN0.5 prepared in Example 1 in a all - solid - state lithium battery, assemble it into a LiFePO4 / PEGMEMA0.5 - PAN0.5 / Li battery and test the charge - discharge cycle performance at 60 °C. Test the charge - discharge cycle. At a 0.1 C rate, the initial discharge specific capacity of the battery is measured to be 154 mAh·g -1 .

[0042] Comparative Example 1 The specific steps for preparing the lithium battery polymer solid electrolyte membrane in Comparative Example 1 are as follows: Dissolve 10.00 g of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and 4.00 g of LiTFSI in 50 ml of dimethylformamide (DMF) solution. Pour the resulting solution onto the surface of a glass mold and vacuum dry it at 60 °C for 24 hours to obtain the lithium battery polymer solid electrolyte membrane, denoted as PVDF-HFP. Assemble the lithium battery polymer solid electrolyte membrane prepared in Comparative Example 1 into a LiFePO4 / PVDF-HFP / Li battery and test its charge-discharge cycle performance at 60 °C. The conductivity of the lithium battery polymer solid electrolyte membrane prepared in Comparative Example 1 at room temperature is 3.57×10 -5 S / cm -1 , and the initial discharge specific capacity of the battery measured at a 0.1C rate is 102 mAh·g -1 .

[0043] As Figure 1 shown, the Fourier infrared spectrum of PEGMEMA0.5-PAN0.5 is presented. Figure 1 The peak around 2251 cm -1 is due to the typical stretching vibration of the nitrile group (-C≡N) in PAN. There is a weak peak at approximately 1650 cm -1 , which is caused by the -C=N stretching vibration of the imidazole ring. The strong peak at 1093 cm -1 is the characteristic peak corresponding to C-O-C in PEGMEMA respectively. These characteristic peaks all indicate the successful preparation of PEGMEMA0.5-PAN0.5.

[0044] As Figure 2 shown, the Li|PEGMEMA0.5-PAN0.5|Li symmetric battery at a constant current density of 0.1 mAcm -2The test was carried out below. The prepared Li|PVDF-HFP|Li symmetric battery was used as a control and tested under the same conditions. According to the test results, it was found that the polarization voltage of the Li|PVDF-HFP|Li battery showed huge fluctuations (from -2V to 2V) during the long-term cycle test. This is because the electron conduction of the thin interfacial layer at high current density is not completely passed, continuously decomposing LiTFSI and hindering its contact with the Li anode. The polarization voltage (170 mV) of the Li|PEGMEMA0.5-PAN0.5|Li battery is relatively stable and basically does not fluctuate during the cycle, and the polarization voltage is very stable. The battery using Li|PEGMEMA0.5-PAN0.5|Li can be cycled stably for more than 2000 h. This is due to the good interfacial compatibility between PEGMEMA0.5-PAN0.5 and lithium metal, indicating the reversible and stable cycle performance of lithium plating / stripping.

[0045] As Figure 3 shown, are the SEM images of the lithium electrode surface after 2000 h of cycling of two symmetric batteries of Li|PEGMEMA0.5-PAN0.5|Li and Li|PVDF-HFP|Li. From Figure 3 Figure (a), it can be found that the surface morphology of the lithium metal corresponding to the symmetric battery of PEGMEMA0.5-PAN0.5 is smooth after cycling, while Figure 3 in Figure (b), the lithium metal of the symmetric battery corresponding to PVDF-HFP shows obvious or slightly obvious lithium dendrites and a pulverized surface; this indicates that PEGMEMA0.5-PAN0.5 has high electrochemical cycle stability, can effectively inhibit the growth of Li dendrites, and effectively improves the interface between the electrode and the electrolyte.

[0046] Example 2 The specific steps for preparing the lithium battery polymer solid electrolyte membrane (PEGMEMA0.7-PAN0.3) in this example are as follows: (1) Weigh 7.00 g of PEGMEMA and 3.00 g of AN and add them to a beaker, and magnetically stir for 5 min in an ice-water bath at 0 °C to obtain a clear and transparent blend solution; (2) Add 4.00 g of LiTFSI, 0.50 g of DVB, and 0.1 g of benzoin ethyl ether to the blend solution obtained in step (1) in sequence. Under a nitrogen atmosphere, magnetically stir for 5 min in an ice-water bath at 0 °C to obtain a precursor solution; (3) Cast the precursor solution obtained in step (2) on the surface of the first glass mold. Place a piece of copper wire at each of the four corners of the first glass mold. The length of the copper wire is 2 cm and the diameter is 30 μm. Then cover the upper layer of the copper wire with the second glass mold. The misalignment angle between the first glass mold and the second glass mold is 30°, so that the precursor solution spreads evenly between the glass molds to the required thickness. The temperature during the entire film coating process is 22-23 °C; (4) Place the glass mold loaded with the precursor solution in step (3) horizontally on the test bench, and irradiate it with UV light with a wavelength of 250 μm for 20 min to initiate the polymerization reaction. After curing, a lithium battery polymer solid electrolyte membrane is obtained, denoted as PEGMEMA0.7-PAN0.3.

[0047] Store PEGMEMA0.7-PAN0.3 in a glove box filled with argon (water < 0.1 ppm, oxygen < 0.1 ppm).

[0048] The lithium battery polymer solid electrolyte membrane prepared in this example is extremely soft. The mechanical strength is too small, resulting in the film being easily broken, and it is difficult to apply in all-solid-state batteries.

[0049] Example 3 The specific steps for preparing the lithium battery polymer solid electrolyte membrane (PEGMEMA0.3-PAN0.7) in this example are as follows: (1) Weigh 3.00 g of PEGMEMA and 7.00 g of AN and add them to a beaker. Magnetically stir for 5 min in an ice-water bath at 0 °C to obtain a clear and transparent blend solution; (2) Sequentially add 4.00 g of LiTFSI, 0.50 g of DVB, and 0.1 g of benzoin ethyl ether to the blend solution obtained in step (1). Under a nitrogen atmosphere, magnetically stir for 5 min in an ice-water bath at 0 °C to obtain a precursor solution; (3) Cast the precursor solution obtained in step (2) on the surface of the first glass mold. Place a piece of copper wire at each of the four corners of the first glass mold. The length of the copper wire is 2 cm and the diameter is 30 μm. Then cover the upper layer of the copper wire with the second glass mold. The misalignment angle between the first glass mold and the second glass mold is 30°, so that the precursor solution spreads evenly between the glass molds to the required thickness. The temperature during the entire film coating process is 22-23 °C; (4) Place the glass mold loaded with the precursor solution in step (3) horizontally on the test bench, and irradiate it with UV light with a wavelength of 250 μm for 20 min to initiate the polymerization reaction. After curing, a lithium battery polymer solid electrolyte membrane is obtained, denoted as PEGMEMA0.3-PAN0.7.

[0050] Store PEGMEMA0.3 - PAN0.7 in a glove box filled with argon gas (water < 0.1 ppm, oxygen < 0.1 ppm).

[0051] The lithium - battery polymer solid - state electrolyte membrane prepared in this example is too rigid at room temperature and has too little flexibility, resulting in easy breakage into blocky transparent membranes, which makes it difficult to apply in all - solid - state batteries.

[0052] Example 4 The specific steps for preparing the lithium - battery polymer solid - state electrolyte membrane (PEGMEMA0.4 - PAN0.6) in this example are as follows: (1) Weigh 4.00 g of PEGMEMA and 6.00 g of AN and add them to a beaker. Magnetically stir for 8 min in an ice - water bath at 5 °C to obtain a clear and transparent blend solution; (2) Sequentially add 3.90 g of LiTFSI, 0.49 g of DVB, and 0.09 g of benzoin ethyl ether to the blend solution obtained in step (1). Under a nitrogen atmosphere, magnetically stir for 8 min in an ice - water bath at 5 °C to obtain a precursor solution; (3) Pour the precursor solution obtained in step (2) onto the surface of the first glass mold. Place a section of copper wire at each of the four corners of the first glass mold. The length of the copper wire is 3 cm and the diameter is 25 μm. Then cover the upper layer of the copper wire with the second glass mold. The misalignment angle between the first glass mold and the second glass mold is 40°, so that the precursor solution spreads evenly between the glass molds to form the required thickness. The temperature during the entire film - coating process is 27 - 28 °C; (4) Horizontally place the glass mold loaded with the precursor solution on the test bench and irradiate it with UV light with a wavelength of 200 μm for 22 min to initiate the polymerization reaction. After curing, a lithium - battery polymer solid - state electrolyte membrane is obtained, denoted as PEGMEMA0.4 - PAN0.6.

[0053] Store PEGMEMA0.4 - PAN0.6 in a glove box filled with argon gas (water < 0.1 ppm, oxygen < 0.1 ppm).

[0054] Assemble the PEGMEMA0.4 - PAN0.6 prepared in this example with the positive electrode (lithium iron phosphate) and the negative electrode (lithium metal sheet) into a 2025 - type button battery for performance testing: The conductivity measured at room temperature is 9.1×10 -4 S / cm -1To detect the application of the lithium battery polymer solid electrolyte membrane prepared in Example 4 in a all-solid-state lithium battery, it was assembled into a LiFePO4 / PEGMEMA0.4-PAN0.6 / Li battery and the charge-discharge cycle performance was tested at 60 °C. The charge-discharge cycle was tested, and the initial discharge specific capacity of the battery was measured to be 121 mAh·g at a rate of 0.1 C. -1 。

[0055] Example 5 The specific steps for preparing the lithium battery polymer solid electrolyte membrane (PEGMEMA0.6-PAN0.4) in this example are as follows: (1) Weigh 6.00 g of PEGMEMA and 4.00 g of AN and add them to a beaker. Magnetically stir for 10 min in an ice-water bath at 4 °C to obtain a clear and transparent blend solution; (2) Add 4.10 g of LiTFSI, 0.51 g of DVB, and 0.11 g of benzoin ethyl ether to the blend solution obtained in step (1) in sequence. Under a nitrogen atmosphere, magnetically stir for 6 min in an ice-water bath at 4 °C to obtain a precursor solution; (3) Pour the precursor solution obtained in step (2) onto the surface of the first glass mold. Place a section of copper wire at each of the four corners of the first glass mold. The length of the copper wire is 2.5 cm and the diameter is 25 μm. Then cover the upper layer of the copper wire with the second glass mold. The misalignment angle between the first glass mold and the second glass mold is 40°, so that the precursor solution spreads evenly between the glass molds to form the required thickness. The temperature during the entire film coating process is 27-28 °C; (4) Horizontally place the glass mold loaded with the precursor solution in step (3) on the test bench, and irradiate it with UV light with a wavelength of 220 μm for 20 min to initiate the polymerization reaction. After curing, a lithium battery polymer solid electrolyte membrane is obtained, denoted as PEGMEMA0.6-PAN0.4.

[0056] Store PEGMEMA0.6-PAN0.4 in a glove box filled with argon (water < 0.1 ppm, oxygen < 0.1 ppm).

[0057] Assemble the PEGMEMA0.6-PAN0.4 prepared in this example with the positive electrode (lithium iron phosphate) and the negative electrode (lithium metal sheet) into a 2025-type button battery for performance testing: The conductivity at room temperature was measured to be 4.5×10 -4 S / cm -1To detect the application of the lithium battery polymer solid electrolyte membrane prepared in Example 5 in all-solid-state lithium batteries, it was assembled into a LiFePO4 / PEGMEMA0.6-PAN0.4 / Li battery and the charge-discharge cycle performance was tested at 60 °C. The charge-discharge cycle was tested, and the initial discharge specific capacity of the battery was measured to be 146 mAh·g at a rate of 0.1C. -1 。

[0058] Example 6 The specific steps for preparing the lithium battery polymer solid electrolyte membrane (PEGMEMA0.45-PAN0.55) in this example are as follows: (1) Weigh 4.50 g of PEGMEMA and 5.50 g of AN and add them to a beaker. Magnetically stir for 10 min in an ice-water bath at 3 °C to obtain a clear and transparent blend solution; (2) Sequentially add 3.90 g of LiTFSI, 0.49 g of DVB, and 0.09 g of benzoin ethyl ether to the blend solution obtained in step (1). Under a nitrogen atmosphere, magnetically stir for 10 min in an ice-water bath at 3 °C to obtain a precursor solution; (3) Pour the precursor solution obtained in step (2) onto the surface of the first glass mold. Place a section of copper wire at each of the four corners of the first glass mold. The length of the copper wire is 3 cm and the diameter is 35 μm; then cover the upper layer of the copper wire with the second glass mold. The misalignment angle between the first glass mold and the second glass mold is 50°, so that the precursor solution spreads evenly between the glass molds to form the required thickness. The temperature during the entire film coating process is 25 - 26 °C; (4) Horizontally place the glass mold loaded with the precursor solution in step (3) on the test bench, and irradiate it with UV light with a wavelength of 260 μm for 18 min to initiate the polymerization reaction. After curing, a lithium battery polymer solid electrolyte membrane is obtained, denoted as PEGMEMA0.45-PAN0.55.

[0059] Store PEGMEMA0.45-PAN0.55 in a glove box filled with argon (water < 0.1 ppm, oxygen < 0.1 ppm).

[0060] Assemble the PEGMEMA0.45-PAN0.55 prepared in this example with the positive electrode (lithium iron phosphate) and the negative electrode (lithium metal sheet) into a 2025-type button battery for performance testing: The conductivity at room temperature was measured to be 8.1×10 -4 S / cm -1To detect the application of the lithium battery polymer solid electrolyte membrane prepared in Example 6 in all-solid-state lithium batteries, it was assembled into a LiFePO4 / PEGMEMA0.45-PAN0.55 / Li battery and the charge-discharge cycle performance was tested at 60 °C. The charge-discharge cycle was tested, and the initial discharge specific capacity of the battery was measured to be 124 mAh·g at a rate of 0.1 C. -1 。

[0061] Example 7 The specific steps for preparing the lithium battery polymer solid electrolyte membrane (PEGMEMA0.55-PAN0.45) in this example are as follows: (1) Weigh 5.50 g of PEGMEMA and 4.50 g of AN and add them to a beaker. Magnetically stir for 10 min in an ice-water bath at 2 °C to obtain a clear and transparent blend solution; (2) Sequentially add 4.10 g of LiTFSI, 0.49 g of DVB, and 0.11 g of benzoin ethyl ether to the blend solution obtained in step (1). Under a nitrogen atmosphere, magnetically stir for 10 min in an ice-water bath at 2 °C to obtain a precursor solution; (3) Pour the precursor solution obtained in step (2) onto the surface of the first glass mold. Place a section of copper wire at each of the four corners of the first glass mold. The length of the copper wire is 2 cm and the diameter is 35 μm. Then cover the upper layer of the copper wire with the second glass mold. The misalignment angle between the first glass mold and the second glass mold is 45°, so that the precursor solution spreads evenly between the glass molds to the required thickness. The temperature during the entire film coating process is 22 - 23 °C; (4) Horizontally place the glass mold loaded with the precursor solution in step (3) on the test bench and irradiate it with UV light with a wavelength of 220 μm for 19 min to initiate the polymerization reaction. After curing, a lithium battery polymer solid electrolyte membrane is obtained, denoted as PEGMEMA0.55-PAN0.45.

[0062] Store PEGMEMA0.55-PAN0.45 in a glove box filled with argon (water < 0.1 ppm, oxygen < 0.1 ppm).

[0063] Assemble the PEGMEMA0.55-PAN0.45 prepared in this example with the positive electrode (lithium iron phosphate) and the negative electrode (lithium metal sheet) into a 2025-type button battery for performance testing: The conductivity at room temperature was measured to be 5.3×10 -4 S / cm -1To detect the application of the lithium battery polymer solid electrolyte membrane prepared in Example 7 in all-solid-state lithium batteries, it was assembled into a LiFePO4 / PEGMEMA0.55-PAN0.45 / Li battery and the charge-discharge cycle performance was tested at 60 °C. The charge-discharge cycle was tested, and the initial discharge specific capacity of the battery was measured to be 143 mAh·g at a rate of 0.1 C. -1 。

[0064] Table 1 shows the mechanical property tests of the lithium battery polymer solid electrolyte membranes prepared in Examples 1-7 and Comparative Example 1.

[0065] As shown in Table 1, for the test results of the mechanical properties of the lithium battery polymer solid electrolyte membranes prepared in Examples 1-7 and Comparative Example 1, the lithium battery polymer solid electrolyte membranes prepared in Examples 1 and 4-7 have moderate flexibility and are suitable for application in all-solid-state batteries. The lithium battery polymer solid electrolyte membrane prepared in Example 2 is extremely soft, and its mechanical strength is too small, resulting in easy fracture of the film; the lithium battery polymer solid electrolyte membrane prepared in Example 3 has too much rigidity at room temperature and too little flexibility, resulting in easy fracture into blocky transparent films. The lithium battery polymer solid electrolyte membrane prepared in the comparative example has strong rigidity and is also easy to fracture. Too strong rigidity or too strong flexibility of the lithium battery polymer solid electrolyte membrane makes it difficult to apply in all-solid-state batteries.

[0066] In summary, the reason for the low conductivity of the lithium battery polymer solid electrolyte membrane prepared in Comparative Example 1 is that PVDF-HFP has a high degree of crystallinity, which inhibits the migration of Li + ; this will further lead to a lower ionic conductivity of the electrolyte. However, the PEGMEMA-PAN obtained by ultraviolet light-induced crosslinking polymerization in the present invention will disrupt the structural arrangement on the original monomers, reduce the crystallinity of the polymer, and promote the migration of lithium ions; in addition, the EO flexible group of PEGMEMA and the nitrile bond in AN can both greatly promote the dissociation of lithium salts, promote the migration of lithium ions, and improve the ionic conductivity. Good lithium ion migration will promote the formation of the solid-electrolyte interphase (SEI, Solid Electrolyte Interface) layer and Li + transmission channels between the lithium battery polymer solid electrolyte membrane and the electrode, further reducing the interfacial polarization and decreasing the interfacial impedance. In addition, AN also has good film-forming properties. By adjusting the ratio of PEGMEMA and AN, a lithium battery polymer solid electrolyte membrane with high flexibility and good mechanical strength is prepared. This property can greatly prevent lithium dendrites from piercing the separator and greatly improve the safety performance of lithium batteries.

[0067] In the ranges disclosed in the present invention, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein. In the following text, in principle, between various technical solutions, they can be combined with each other to obtain new technical solutions, and this should also be regarded as specifically disclosed herein.

[0068] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art can still modify the specific implementation manners of the present invention or make equivalent replacements. Any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are within the scope of the claims of the present invention pending approval.

Claims

1. A preparation method of a lithium battery polymer solid electrolyte membrane with rapid polymerization at room temperature, characterized in that Including: Mixing polyethylene glycol methyl ether methacrylate and acrylonitrile uniformly to obtain a blend solution; Adding lithium bis(trifluoromethanesulfonyl)imide, divinylbenzene and benzoin ethyl ether to the blend solution and mixing uniformly to obtain a precursor solution; Performing a coating treatment on the precursor solution and performing an ultraviolet curing treatment on the precursor solution to obtain a lithium battery polymer solid electrolyte membrane.

2. The preparation method of the lithium battery polymer solid electrolyte membrane with rapid polymerization at room temperature according to claim 1, characterized in that The step of mixing polyethylene glycol methyl ether methacrylate and acrylonitrile uniformly to obtain a blend solution is specifically as follows: The mass ratio of polyethylene glycol methyl ether methacrylate to acrylonitrile is (3-7):(7-3); Mixing polyethylene glycol methyl ether methacrylate and acrylonitrile in an ice-water bath at a temperature of 0-5°C with magnetic stirring for 5-10 minutes to obtain a blend solution.

3. The preparation method of the lithium battery polymer solid electrolyte membrane with rapid polymerization at room temperature according to claim 1, characterized in that, The addition amount of lithium bis(trifluoromethanesulfonyl)imide is 39%-41% of the total mass of polyethylene glycol methyl ether methacrylate and acrylonitrile.

4. The preparation method of the lithium battery polymer solid electrolyte membrane with rapid polymerization at room temperature according to claim 1, characterized in that The addition amount of divinylbenzene is 4.9%-5.1% of the total mass of polyethylene glycol methyl ether methacrylate and acrylonitrile; the addition amount of benzoin ethyl ether is 0.9%-1.1% of the total mass of polyethylene glycol methyl ether methacrylate and acrylonitrile.

5. The preparation method of the lithium battery polymer solid electrolyte membrane with rapid polymerization at room temperature according to claim 1, characterized in that The step of adding lithium bis(trifluoromethanesulfonyl)imide, divinylbenzene and benzoin ethyl ether to the blend solution in sequence and mixing uniformly to obtain a precursor solution, wherein the condition for uniform mixing is: in an inert atmosphere, magnetic stirring in an ice-water bath at a temperature of 0-5°C for 5-10 minutes.

6. The preparation method of the lithium battery polymer solid electrolyte membrane with rapid polymerization at room temperature according to claim 1, characterized in that, The step of performing a coating treatment on the precursor solution is specifically as follows: Coating the precursor solution on the surface of a first film-forming mold, placing copper wires at the four corners of the first film-forming mold respectively, and then covering the second film-forming mold on the upper layer of the copper wires to spread the precursor solution evenly; The length of the copper wire is 2-3 cm, the diameter is 25-35 μm, the misalignment angle between the first film-forming mold and the second film-forming mold is 30-50°, and the temperature during the coating process is 22-28°C.

7. The preparation method of the lithium battery polymer solid electrolyte membrane with rapid polymerization at room temperature according to claim 1, characterized in that, The conditions for the ultraviolet curing treatment are specifically as follows: The ultraviolet light wavelength is 200-260 μm, and the illumination time is 18-22 minutes.

8. The preparation method of the lithium battery polymer solid electrolyte membrane with rapid polymerization at room temperature according to claim 1, characterized in that, The lithium battery polymer solid electrolyte membrane is stored in an argon environment, and in the argon environment, water < 0.1 ppm and oxygen < 0.1 ppm.

9. A lithium battery polymer solid electrolyte membrane with rapid polymerization at room temperature, characterized in that, Prepared according to the preparation method of the lithium battery polymer solid electrolyte membrane with rapid polymerization at room temperature described in claim 1, the lithium battery polymer solid electrolyte membrane includes a polymer matrix and a lithium salt, the polymer matrix is polymerized from polyethylene glycol methyl ether methacrylate and acrylonitrile, and the structural formula of the polymer matrix is: In the formula, x and y represent the mass ratio of polyethylene glycol methyl ether methacrylate to acrylonitrile, and x + y = 1.

10. Use of a lithium battery polymer solid electrolyte membrane that rapidly polymerizes at room temperature according to claim 9, characterized in that, The lithium battery polymer solid electrolyte membrane is used for lithium ion batteries.

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