A preparation method of polymer solid electrolyte based on electrospinning technology

Abstract

The present invention discloses a preparation method of a polymer solid electrolyte based on electrostatic spinning technology, which belongs to the technical field of all-solid-state lithium battery manufacturing. The present invention mixes a polymer solution with an ionic liquid solution, heats the solvent in a water bath, and obtains a polymer ionic liquid mixed solution; the mixed solution is subjected to electrostatic spinning, a high-speed receiving roller is used to receive the film, and the film is dried and removed in a vacuum oven to obtain an oriented Poly (x) IL EA film; the film Poly (x) IL EA is then immersed in a pre-prepared high-concentration lithium salt ionic liquid solution, and a polymer composite all-solid-state electrolyte Li Poly (x) IL EA is obtained by ion replacement. The polymer solid electrolyte prepared by the method of the present invention has a significantly improved energy density under the same mass and same volume conditions, has significant economic value, and can be applied to high-energy-density, high-safety lithium metal batteries.

Description

Technical Field

[0001] The present invention belongs to the technical field of all-solid-state lithium battery manufacturing, and in particular relates to a method for preparing a polymer solid electrolyte based on electrospinning technology. Background Art

[0002] In the current field of energy storage and conversion technology, the research and development of high-performance solid electrolyte materials has become one of the key challenges, especially in the application context of solid-state batteries with high safety and high energy density. Ionic liquid-based polymer solid electrolytes are widely considered to be potential materials due to their unique physicochemical properties, such as excellent thermal stability, wide electrochemical window, extremely low interfacial impedance and high ionic conductivity (Adv.Energy Mater.2024,2400956.). However, to maximize the potential of these materials in practical applications, it is also necessary to overcome the problems of high thickness and insufficient mechanical strength of solid electrolytes. These challenges urgently need to be addressed through new material design and processing technologies. Summary of the Invention

[0003] To address the above technical issues, the present invention proposes a method for preparing a polymer solid electrolyte based on electrospinning technology. This method utilizes electrospinning and high-speed orientation to prepare an ionic liquid polymer electrospun film. This method then uses ion exchange to in situ synthesize an ionic liquid-based polymer solid electrolyte. This electrolyte exhibits high energy density per unit mass and volume, and its mechanical properties do not decrease with thinning.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A method for preparing a polymer solid electrolyte based on electrospinning technology comprises the following steps:

[0006] A polymer (Poly) and a polymer spinning aid (EA) are dissolved in a solvent to obtain a polymer solution; an ionic liquid (IL) is dissolved in a solvent to obtain an ionic liquid solution;

[0007] mixing the polymer solution with the ionic liquid solution to obtain a uniform mixed solution;

[0008] The mixed solution is subjected to electrospinning-high-speed receiving orientation film formation to obtain Poly(x)-IL-EA, wherein x represents the percentage of the polymer in the total mass of the polymer and the ionic liquid, and the total mass refers to the sum of the masses of the polymer and the ionic liquid (excluding the polymer spinning aid);

[0009] The Poly(x)-IL-EA is dried and then immersed in an ion solution containing a lithium salt for ion replacement to obtain a polymer solid electrolyte Li-Poly(x)-IL-EA based on electrospinning technology.

[0010] Furthermore, the polymer is one of poly-2,2'-disulfonyl-4,4'-benzidine terephthalamide (PBDT), sodium alginate (SA), and sodium carboxymethyl cellulose (CMC). The polymers selected in the present invention are all water-soluble polymers, and their main chains have high rigidity and structural stability, and their main chains contain ionic groups (such as sodium carboxylate, sodium sulfonate, etc.).

[0011] Furthermore, the polymer spinning aid is polyethylene glycol (PEG), polyethylene oxide (PEO), polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP) or polyacrylamide (PAM).

[0012] Furthermore, the ionic liquid is at least one of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (C2mimTfO), 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (C2mimFSI), 1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide (C3mpyrFSI) and 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide (C2mimTFSI).

[0013] Furthermore, the solvent of the polymer is water, and the solvent of the ionic liquid is water or N,N-dimethylformamide (DMF).

[0014] Furthermore, the mass ratio of the ionic liquid to the solvent is (0.15-0.6):10.

[0015] Furthermore, the masses of the solvents in the polymer solution and the ionic liquid solution are equal.

[0016] Furthermore, in the mixed solution, the amount of polymer added is 2-50% of the total mass of the polymer, the polymer spinning aid and the ionic liquid.

[0017] Furthermore, the added amount of the polymer spinning aid is 10-100% of the mass of the polymer.

[0018] Furthermore, the parameters in the electrospinning-high-speed receiving orientation film forming process are: voltage 5-25 kV, distance from the needle to the receiving roller 5-30 cm, and solution advancing speed 0.5-8 ml / h.

[0019] Furthermore, in the electrospinning-high-speed receiving orientation film-forming process, a cylindrical receiving roller driven by a motor is used, and the receiving rotation speed is 100-5000 revolutions per minute.

[0020] Furthermore, the preparation method further comprises, after the electrospinning-high-speed receiving orientation film formation is completed, continuing electrospinning by rotating the film to achieve the superposition of electrospun membranes oriented in multiple directions.

[0021] Furthermore, the soaking time is 8-48 hours.

[0022] Furthermore, in the ionic solution containing lithium salt, the molar ratio of lithium salt to ionic liquid is (0.5-1.5):1.

[0023] Furthermore, the lithium salt is lithium bis(fluorosulfonyl)imide (LiFSI) or lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

[0024] Furthermore, the ionic liquid is at least one of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

[0025] Compared with the prior art, the present invention has the following advantages and technical effects:

[0026] This invention uses polymers and ionic liquids as raw materials to prepare ionic liquid-based polymer solid electrolytes. Electrospinning effectively creates ultrathin fibers. During this process, a high-speed rotating receiving roller is used to directional stretch the fibers, significantly increasing their mechanical modulus. The result is a polymer solid electrolyte with both extremely low thickness and ultrahigh mechanical strength. The polymer solid electrolyte produced using this method exhibits significantly increased energy density at the same mass and volume, demonstrating significant economic value.

[0027] The ionic liquid-based polymer solid electrolyte prepared by the present invention has an ultra-thin and adjustable thickness (as low as 7.5 μm), ultra-high mechanical strength (tensile modulus can be as high as 1.279 GPa), excellent flexibility and high thermal stability (PBDT(x)-IL-PEG decomposition temperature is higher than 300°C, and Li-PBDT(x)-IL-PEG decomposition temperature is higher than 200°C), and at the same time has high ionic conductivity (the ionic conductivity of Li-PBDT(10)-IL-PEG at 30°C is 3.07 mS / cm), low internal resistance and interface resistance (the interface resistance of the lithium metal symmetric battery assembled by Li-PBDT(10)-IL-PEG ionic liquid-based polymer electrolyte is 2.3Ω·cm 2 ), which is of great significance in the development and application of lithium metal batteries with large capacity, high power, high energy density and high safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0029] Figure 1 It is a process flow chart of the present invention;

[0030] Figure 2 This is a flow chart of electrospinning-high-speed receiving and oriented film formation according to the present invention;

[0031] Figure 3 Schematic diagram of the thickness of the electrospun films PBDT(30)-IL-PEG, PBDT(20)-IL-PEG, and PBDT(10)-IL-PEG prepared in Examples 1-3;

[0032] Figure 4 Tensile stress-strain curves of the electrospun films PBDT(30)-IL-PEG, PBDT(20)-IL-PEG, and PBDT(10)-IL-PEG prepared in Examples 1-3;

[0033] Figure 5 TGA curves of the electrospun films PBDT(30)-IL-PEG, PBDT(20)-IL-PEG and PBDT(10)-IL-PEG, as well as Li-PBDT(30)-IL-PEG, Li-PBDT(20)-IL-PEG and Li-PBDT(10)-IL-PEG prepared in Examples 1-3; A is the TGA curve of the electrospun films PBDT(30)-IL-PEG, PBDT(20)-IL-PEG and PBDT(10)-IL-PEG before replacement; B is the TGA curve of Li-PBDT(30)-IL-PEG, Li-PBDT(20)-IL-PEG and Li-PBDT(10)-IL-PEG after ion replacement;

[0034] Figure 6 A is the temperature-resistance curve of the stainless steel symmetric battery assembled by Li-PBDT(30)-IL-PEG, Li-PBDT(20)-IL-PEG and Li-PBDT(10)-IL-PEG prepared in Example 1-3; B is the interface resistance curve of the lithium metal symmetric battery assembled by Li-PBDT(30)-IL-PEG, Li-PBDT(20)-IL-PEG and Li-PBDT(10)-IL-PEG prepared in Example 1-3; C is the interface resistance curve of Li-PBDT(30)-IL-PEG, Li-PBDT(20)-IL-PEG and Li-PBDT(10)-IL-PEG prepared in Example 1-3 at different current densities (0.1-4 mA / cm2 ) of lithium symmetric battery cycle characteristics curve;

[0035] Figure 7 A is the Li-PBDT(10)-IL-PEG prepared in Example 3. The lithium metal symmetric battery is at room temperature (28°C) at 0.5 mA / cm 2 At current density (0.25mAh / cm 2 ) long cycle results; B is the Li-PBDT (10) -IL-PEG prepared in Example 3 at room temperature (28 ° C) lithium iron phosphate (surface loading of 10.52 mg / cm 2 ) for the rate performance of lithium metal batteries; C is the Li-PBDT (10) -IL-PEG prepared in Example 3 at room temperature (28 ° C) of lithium iron phosphate (11.25 mg / cm 2 ) for the long cycle performance of lithium metal batteries at 1C (charge 1h, discharge 1h) rate; D is the Li-PBDT (10) -IL-PEG prepared in Example 3 at room temperature (28 ° C) of lithium iron phosphate (10.52 mg / cm 2 ) Long cycle performance of lithium metal batteries at a rate of 0.5C (charge 2h, discharge 2h);

[0036] Figure 8 The interfacial resistance curves of Li-PBDT(20)-IL-PEG, Li-SA(20)-IL-PEG and Li-CMC(20)-IL-PEG prepared in Example, Example 4 and Example 5 in lithium metal symmetric batteries at room temperature. DETAILED DESCRIPTION

[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0038] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0039] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0040] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0041] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0042] This invention develops an ionic liquid-based polymer solid electrolyte that combines ultrahigh modulus to ensure mechanical stability with high ionic conductivity and low interfacial resistance. This research holds significant technical and commercial value for advancing solid-state battery technology. By optimizing the electrospinning process's preparation parameters and post-processing, solid-state electrolytes with optimized structure and performance can be obtained. This will directly contribute to the construction of high-performance energy storage systems and is a current research hotspot and development direction.

[0043] The present invention discloses a method for preparing a polymer solid electrolyte based on electrospinning technology, comprising the following steps:

[0044] (1) dissolving a polymer (Poly) and a polymer spinning aid (EA) in a solvent to obtain a polymer solution; the dissolution is specifically performed by heating in a water bath at 45-65°C and magnetically stirring for 30-60 minutes until the polymer solution is uniformly dispersed. The hydrothermal temperature and stirring time are not specifically limited as long as the polymer and the polymer spinning aid are fully dissolved. As an example, in the following embodiments of the present invention, heating in a water bath at 60°C and magnetically stirring for 30 minutes is selected;

[0045] The ionic liquid (IL) is dissolved in a solvent to obtain an ionic liquid solution; the dissolution is specifically performed by heating in a water bath at 45-65° C. and magnetically stirring for 30-60 minutes until the ionic liquid is uniformly dispersed. The hydrothermal temperature and stirring time are not specifically limited as long as the ionic liquid can be fully dissolved. As an example, in the following embodiments of the present invention, heating in a water bath at 60° C. and magnetically stirring for 30 minutes is selected;

[0046] (2) mixing the polymer solution and the ionic liquid solution while hot, and continuing heating and stirring to obtain a uniform mixed solution; the continued heating and stirring means: heating in a 45-65°C water bath and magnetically stirring for 30-60 minutes. There is no specific limitation on the hydrothermal temperature and stirring time, as long as the polymer solution and the ionic liquid solution are fully mixed. As an example, in the following embodiments of the present invention, heating in a 60°C water bath and magnetically stirring for 30 minutes is selected;

[0047] (3) pouring the mixed solution into a syringe for electrospinning-high-speed receiving orientation to form an electrospun film Poly(x)-IL-EA, wherein x represents the percentage of the polymer in the total mass of the polymer and the ionic liquid (excluding the polymer spinning aid);

[0048] (4) drying the electrospun film Poly(x)-IL-EA; drying means drying in a vacuum oven at 80-100°C for 24-48 hours until the solvent is completely removed. The temperature and time are not specifically limited, and the solvent can be completely removed. As an example, in the following embodiments of the present invention, vacuum drying at 80°C for 48 hours is selected;

[0049] (5) The fully dried electrospun film Poly(x)-IL-EA is immersed in an ionic solution containing a lithium salt for ion replacement, and then the ionic liquid solution on the film is wiped off with a dust-free paper to obtain a polymer solid electrolyte Li-Poly(x)-IL-EA based on electrospinning technology; the ion replacement time can be achieved by meeting 8-48 hours. As an example, ion replacement for 24 hours is selected in the following embodiments of the present invention.

[0050] Electrospinning technology is easy to operate, low-cost, and can produce fibers with unique micro-nano structures. It has become one of the important technical routes for preparing high-performance polymer-based nanofibers. Using electrospinning technology, the arrangement of polymer chains and the structure of micro-nano fibers can be regulated at the molecular level, thereby achieving precise control of the final material properties. When preparing ionic liquid-based polymer solid electrolytes, the present invention effectively realizes the preparation of ultra-thin fibers through electrospinning technology, and in this process uses a high-speed rotating receiving roller to directional stretch and orientation the fibers, thereby greatly improving their mechanical modulus, thereby achieving a polymer solid electrolyte with extremely low thickness and ultra-high mechanical strength. This is of great significance for the development of high-performance and high-safety solid-state batteries. The polymer solid electrolyte prepared by the method of the present invention has significantly improved energy density under the same mass and volume conditions, and also has higher mechanical properties, and has significant economic value.

[0051] In the following preferred embodiments of the present invention, the polymer in step (1) is one of poly 2,2'-disulfonyl-4,4'-benzidine terephthalamide (PBDT), sodium alginate (SA) and sodium carboxymethyl cellulose (CMC). As an example, in the following embodiments of the present invention, the polymer is poly 2,2'-disulfonyl-4,4'-benzidine terephthalamide. The synthesis method thereof is not considered as a factor in the inventiveness of the present invention. For the specific synthesis method, please refer to the literature: Sarkar, N., and L.D. Kershner. "Rigid rod water-soluble polymers." Journal of applied polymer science 62.2 (1996): 393-408.

[0052] The polymer spinning aid is at least one of water-soluble polymers such as polyethylene glycol, polyethylene oxide, polyvinyl alcohol, polyvinyl pyrrolidone, and polyacrylamide. All of the above polymer spinning aids can produce products with good performance. As an example, the performance of polyethylene glycol is discussed in the following examples.

[0053] The ionic liquid is at least one of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide, and 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide. All of the above ionic liquids can produce products with good performance. As an example, the performance of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate is discussed in the following examples.

[0054] The solvent of the polymer is water, and the solvent of the ionic liquid is water or N,N-dimethylformamide (DMF). Water or N,N-dimethylformamide can be used as solvents to obtain products with good performance. As an example, the performance is discussed using deionized water as an example in the following embodiments.

[0055] In order to obtain the target product, the mass ratio of the ionic liquid to the solvent of the present invention is (0.15-0.6):10.

[0056] In order to obtain the target product, the masses of the solvents in the polymer solution and the ionic liquid solution of the present invention are equal.

[0057] In the mixed solution of step (2) of the following preferred embodiments of the present invention, the amount of polymer added is 2-50% of the total mass of the polymer, polymer and ionic liquid. Within this range, products with good performance can be obtained. As an example, the following embodiments of the present invention use 10%, 20% and 30% as examples to discuss performance. The amount of the polymer spinning aid added is 10-100% of the mass of the polymer. Within this range, products with good performance can be obtained. As an example, the following embodiments of the present invention use 50% as an example to discuss performance.

[0058] The spinning process can obtain the target product as long as the following parameters are met. In the following preferred embodiment step (3) of the present invention, the parameters in the electrostatic spinning-high-speed receiving orientation film-forming process are: voltage 5-25kV, distance from needle to receiving roller 5-30cm, solution propulsion speed 0.5-8ml / h. Electrostatic spinning-high-speed receiving orientation adopts a motor-driven cylindrical receiving roller, and its receiving speed is controlled at 100-5000 rpm. As an example, the parameters in the electrostatic spinning-high-speed receiving orientation film-forming process in the following embodiment of the present invention are: voltage 15kV, distance from needle to receiving roller 15cm, solution propulsion speed 0.54ml / h. Electrostatic spinning-high-speed receiving orientation adopts a motor-driven cylindrical receiving roller, and its receiving speed is controlled at 2800 rpm.

[0059] The preparation method further includes, after the electrospinning is completed, continuing the electrospinning by rotating the film to achieve the superposition of electrospun membranes oriented in multiple directions. As an example, in the following embodiments of the present invention, the electrospun membranes oriented in two orthogonal directions are superimposed.

[0060] The present invention adjusts the film thickness by adjusting the combined mass of the polymer, polymer spinning aid, and ionic liquid. The resulting electrospun film, Poly(x)-IL-EA, has a thickness of 5-100 μm, preferably 7-10 μm, and exhibits excellent mechanical and electrochemical properties. The prepared electrospun film can be oriented in any direction from 0 to 180 degrees, maintaining excellent mechanical properties in each orientation direction.

[0061] In step (4) of the following preferred embodiment of the present invention, the target sample can be obtained when the soaking time is 8-48 hours. As an example, the performance is discussed by taking the soaking time of 24 hours as an example in the following embodiment of the present invention.

[0062] The target product can be obtained if the ionic solution containing the lithium salt satisfies the following conditions: the molar ratio of the lithium salt to the ionic liquid is (0.5:1) to (1.5:1); the lithium salt is lithium bis(fluorosulfonyl)imide or lithium bis(trifluoromethanesulfonyl)imide; and the ionic liquid is at least one of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide, and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide. As an example, the following embodiments of the present invention use a molar ratio of the lithium salt to the ionic liquid of 1:1, the lithium salt is lithium bis(fluorosulfonyl)imide, and the ionic liquid is 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide as an example to discuss performance.

[0063] Exemplarily, a method for preparing a polymer solid electrolyte based on electrospinning technology comprises the following steps:

[0064] (1) dissolving the polymer (PBDT) and the polymer spinning aid (PEG) in a solvent, heating in a water bath at 45-65°C and magnetically stirring for 30-60 minutes until the polymer solution is uniformly dispersed;

[0065] Dissolve the ionic liquid (C2mimTFO) in a solvent, heat in a water bath at 45-65°C and magnetically stir for 30-60 minutes until the mixture is uniformly dispersed to obtain an ionic liquid solution;

[0066] (2) mixing the polymer solution and the ionic liquid solution while hot, and continuing to heat in a water bath at 45-65° C. and magnetically stirring for 30-60 minutes to obtain a uniform mixed solution;

[0067] (3) pouring the mixed solution into a syringe for electrospinning-high-speed receiving orientation film formation at a voltage of 10-25 kV, a distance from the needle to the receiving roller of 5-30 cm, and a solution advancing speed of 0.5-8 ml / h to obtain an electrospun film PBDT(x)-IL-PEG, where x represents the percentage of PBDT in the total mass of PBDT and C2mimTFO;

[0068] (4) drying the electrospun PBDT(x)-IL-PEG film in a vacuum oven at 80-100° C. for 24-48 h until the solvent is completely removed;

[0069] (5) The fully dried electrospun film PBDT(x)-IL-PEG is immersed in an ionic solution containing lithium salt for 24-48 hours for ion replacement, and then the ionic liquid solution on the film is wiped off with dust-free paper to obtain a polymer solid electrolyte Li-Poly(x)-IL-PEG based on electrospinning technology.

[0070] Unless otherwise specified, the "normal temperature" mentioned in the present invention refers to 28±0.5°C.

[0071] The raw materials used in the present invention are all purchased from the market.

[0072] The technical solution of the present invention is further illustrated by the following examples.

[0073] Example 1

[0074] A method for preparing a polymer solid electrolyte based on electrospinning technology (see the flow chart Figure 1 , electrospinning - high speed receiving orientation film formation see Figure 2 ), including the following steps:

[0075] (1) Dissolve 0.1 g of polymer (PBDT) and 0.05 g of polymer spinning aid (PEG) in 15 g of deionized water, heat in a 60 °C water bath and magnetically stir for 30 min until the mixture is uniformly dispersed to obtain a polymer solution;

[0076] 0.23 g of ionic liquid (1-ethyl-3-methylimidazolium trifluoromethanesulfonate, C2mimTfO) was dissolved in 15 g of deionized water, heated in a 60 °C water bath and magnetically stirred for 30 min until uniformly dispersed to obtain an ionic liquid solution;

[0077] (2) mixing the polymer solution and the ionic liquid solution while still hot, and continuing to heat in a 60° C. water bath with magnetic stirring for 30 min to obtain a uniform mixed solution;

[0078] (3) pouring the mixed solution into a syringe for electrospinning-high-speed receiving orientation film formation, the receiving roller speed is 2800 rpm, the voltage is 15 kV, the distance from the needle to the receiving roller is 15 cm, the solution advancement speed is 0.54 ml / h, spinning 20 ml of spinning solution, removing the film from the receiving roller, placing it horizontally on the receiving roller, and continuing to spin 20 ml of spinning solution to obtain an electrospun film PBDT(30)-IL-PEG oriented in two orthogonal directions;

[0079] (4) drying the electrospun PBDT(30)-IL-PEG film in a vacuum oven at 80° C. for 48 h until the solvent is completely removed;

[0080] (5) The fully dried electrospun film PBDT(30)-IL-PEG was immersed in an ionic solution containing lithium salt (the lithium salt was lithium bis(fluorosulfonyl)imide, the ionic liquid was 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, and the molar ratio of lithium salt to ionic liquid was 1:1) for 24 hours of ion replacement. The ionic liquid solution on the film was then wiped off with dust-free paper to obtain the polymer solid electrolyte Li-PBDT(30)-IL-PEG based on electrospinning technology.

[0081] Example 2

[0082] The same as Example 1, except that the mass of the ionic liquid (1-ethyl-3-methylimidazolium trifluoromethanesulfonate, C2mimTfO) in step (1) is replaced with 0.4 g to obtain the electrospun film PBDT(20)-IL-PEG, and finally obtain the polymer solid electrolyte Li-PBDT(20)-IL-PEG based on electrospinning technology.

[0083] Example 3

[0084] The same as Example 1, except that the mass of the ionic liquid (1-ethyl-3-methylimidazolium trifluoromethanesulfonate, C2mimTfO) in step (1) is replaced with 0.9 g to obtain the electrospun film PBDT(10)-IL-PEG, and finally obtain the polymer solid electrolyte Li-PBDT(10)-IL-PEG based on electrospinning technology.

[0085] Example 4

[0086] The same as Example 2, except that the polymer (PBDT) is replaced with sodium alginate (SA) to obtain the electrospun film SA(20)-IL-PEG, and finally the polymer solid electrolyte Li-SA(20)-IL-PEG based on electrospinning technology is obtained.

[0087] Example 5

[0088] The same as Example 2, except that the polymer (PBDT) is replaced with sodium carboxymethyl cellulose (CMC) to obtain the electrospun film CMC (20) -IL-PEG, and finally the polymer solid electrolyte Li-CMC (20) -IL-PEG based on electrospinning technology is obtained.

[0089] Figure 3 Schematic diagram of the thickness of the electrospun films PBDT(30)-IL-PEG, PBDT(20)-IL-PEG and PBDT(10)-IL-PEG prepared in Examples 1-3. It can be seen from the figure that the films prepared by the method of the present invention have an extremely low thickness of 7.5 μm, and the maximum thickness does not exceed 10 μm.

[0090] Figure 4 The tensile stress-strain curves of the electrospun films PBDT(30)-IL-PEG, PBDT(20)-IL-PEG, and PBDT(10)-IL-PEG prepared in Examples 1-3 show that the tensile modulus of the films gradually increases with increasing poly (2,2-disulfonyl-4,4-benzidine terephthalamide) content, with the tensile modulus of PBDT(30)-IL-PEG reaching 1.279 GPa.

[0091] Figure 5TGA curves of the electrospun films PBDT(30)-IL-PEG, PBDT(20)-IL-PEG and PBDT(10)-IL-PEG, as well as Li-PBDT(30)-IL-PEG, Li-PBDT(20)-IL-PEG and Li-PBDT(10)-IL-PEG prepared in Examples 1-3. Figure 5 A in FIG is the TGA curve of the electrospun films PBDT(30)-IL-PEG, PBDT(20)-IL-PEG and PBDT(10)-IL-PEG before replacement. It can be seen that the films prepared using the method of the embodiment of the present invention have excellent thermal stability before replacement, and the decomposition temperature reaches above 300°C. Figure 5 Figure B shows the TGA curves of Li-PBDT(30)-IL-PEG, Li-PBDT(20)-IL-PEG, and Li-PBDT(10)-IL-PEG after ion exchange. It can be seen that within 200°C, the main decomposition factor is the evaporation of water absorbed by the electrolyte membrane in the air. When the temperature is higher than 200°C, the components in the electrolyte membrane gradually begin to decompose, indicating that the electrolyte membrane has a relatively wide operating temperature range. This is mainly because the materials used in the electrolyte membrane have a high decomposition temperature, and secondly, there is a strong interaction between the materials.

[0092] After the Li-PBDT(30)-IL-PEG, Li-PBDT(20)-IL-PEG and Li-PBDT(10)-IL-PEG prepared in Examples 1-3 were assembled into battery cells with stainless steel pole pieces, they were packaged in a shell with a packaging pressure of 0.8T to obtain a stainless steel symmetrical battery.

[0093] Li-PBDT(30)-IL-PEG, Li-PBDT(20)-IL-PEG and Li-PBDT(10)-IL-PEG prepared in Examples 1-3 were assembled into battery cells with lithium metal electrodes, and then packaged in a shell with a packaging pressure of 0.8T to obtain a lithium metal symmetrical battery.

[0094] Figure 6 Figure A is the temperature-resistance curve of the stainless steel symmetric battery assembled with Li-PBDT(30)-IL-PEG, Li-PBDT(20)-IL-PEG and Li-PBDT(10)-IL-PEG prepared in Examples 1-3; it can be seen from Figure A that the polymer solid electrolyte prepared by the method of Examples 1-3 of the present invention has extremely low bulk resistance, among which the stainless steel symmetric battery assembled with Li-PBDT(10)-IL-PEG exhibits an ionic conductivity of 3.07 mS / cm at 30°C.

[0095] Figure 6Figure B is the interfacial resistance curve of the lithium metal symmetric battery assembled by Li-PBDT(30)-IL-PEG, Li-PBDT(20)-IL-PEG and Li-PBDT(10)-IL-PEG prepared in Examples 1-3; As can be seen from Figure B, the electrochemical impedance spectrum of the lithium metal symmetric battery, Li|Li-PBDT(10)-IL-PEG|Li has 2.3Ω·cm 2 Low interface resistance.

[0096] Figure 6 C is the Li-PBDT(30)-IL-PEG, Li-PBDT(20)-IL-PEG and Li-PBDT(10)-IL-PEG prepared in Examples 1-3 at different current densities (0.1-4 mA / cm 2 ) of the lithium symmetric battery cycle characteristic curve. As can be seen from Figure C, the cycle performance of the lithium metal symmetric battery at different current densities at 28 ° C, among which the lithium metal battery assembled by Li-PBDT (10) -IL-PEG shows a 4mA / cm 2 High limiting current density and low overpotential (4mA / cm 2 , 65mV), which is closely related to the high conductivity and low interfacial resistance of Li-PBDT(10)-IL-PEG in Figures A and B; and it can be found from Figures A, B, and C that the bulk conductivity of the electrolyte film, the interfacial compatibility with the lithium metal electrode, and the critical current density all increase with the decrease of the mass fraction of poly (2,2-disulfonyl-4,4-benzidine terephthalamide), which indicates that the content of ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate determines some of the electrochemical properties of the electrolyte film.

[0097] After the Li-PBDT(10)-IL-PEG prepared in Example 3 was assembled with the lithium iron phosphate positive electrode membrane and the lithium metal negative electrode membrane into a battery cell, it was packaged in a shell with a packaging pressure of 0.8T to obtain a lithium iron phosphate lithium metal symmetrical battery.

[0098] Figure 7 A is the Li-PBDT(10)-IL-PEG prepared in Example 3. The lithium metal symmetric battery is at room temperature (28°C) at 0.5 mA / cm 2 At current density (0.25mAh / cm 2 ) long cycle results; As can be seen from Figure A, the long cycle performance of the lithium metal symmetric battery assembled by Li-PBDT(10)-IL-PEG at 28 ° C is 0.5 mA / cm 2 (0.25mAh / cm 2), showing a stable cycling capability of more than 3200 h and an extremely low overpotential (<30 mV).

[0099] Figure 7 B is the Li-PBDT(10)-IL-PEG prepared in Example 3 at room temperature (28°C) with lithium iron phosphate (surface loading of 10.52 mg / cm 2 ) for the rate performance results of lithium metal batteries; As can be seen from Figure B, at a rate of 0.5C, 152.45 mAh g -1 The capacity is maintained at 142.43 mAh g at a rate of 1C. -1 The capacity is maintained at 120.58 mAh g at a high rate of 2C. -1 The capacity can still maintain 53.4mAh g at an extremely high rate of 5C. -1 The capacity can still return to 151.65mAh g when the rate returns from 5C to 0.5C. -1 (The capacity loss is only 0.53%), showing excellent reversible performance.

[0100] Figure 7 C is the Li-PBDT(10)-IL-PEG prepared in Example 3 at room temperature (28°C) and lithium iron phosphate (11.25 mg / cm 2 ) The long-cycle performance of lithium metal batteries at a rate of 1C (charge 1h, discharge 1h); as can be seen from Figure C, the battery can be stably cycled for >450h (230 cycles, two hours per cycle) at a rate of 1C, with an average coulombic efficiency of >99.8% and a capacity retention rate of 88.92%.

[0101] Figure 7 D is the Li-PBDT(10)-IL-PEG prepared in Example 3 at room temperature (28°C) and lithium iron phosphate (10.52 mg / cm 2 ) The long cycle performance of lithium metal batteries at a rate of 0.5C (charge 2h, discharge 2h); as can be seen from Figure D, the stable cycle can be >1520h at a rate of 0.5C, the average coulombic efficiency is >99.9%, and the capacity retention rate is 89.59%.

[0102] Li-PBDT(20)-IL-PEG, Li-SA(20)-IL-PEG and Li-CMC(20)-IL-PEG prepared in Example 2 and Example 4 were respectively assembled with lithium metal pole pieces into battery cells, which were then packaged in a shell with a packaging pressure of 0.8T to obtain a lithium metal symmetrical battery.

[0103] Figure 8The interface resistance curves of the lithium metal symmetric battery assembled by Li-PBDT(20)-IL-PEG, Li-SA(20)-IL-PEG and Li-CMC(20)-IL-PEG prepared in Example 2, Example 4 and Example 5; The interface resistance curves of the lithium metal symmetric battery assembled; Figure 8 As can be seen from the electrochemical impedance spectroscopy of the lithium metal symmetric battery, Li|Li-PBDT(20)-IL-PEG|Li has a value of 4.2Ω·cm 2 The low interfacial resistance of Li|Li-SA(20)-IL-PEG|Li is 2.0Ω·cm 2 The low interfacial resistance of Li|Li-CMC(20)-IL-PEG|Li is 1.1Ω·cm 2 Low interface resistance.

[0104] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of this application. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for preparing a polymer solid electrolyte based on electrospinning technology, characterized in that: The following steps are involved: dissolving a polymer and a polymer spinning aid in a solvent to obtain a polymer solution; dissolving an ionic liquid in a solvent to obtain an ionic liquid solution; mixing the polymer solution with the ionic liquid solution to obtain a uniform mixed solution; The mixed solution is subjected to electrospinning-high-speed receiving orientation to form a film to obtain Poly(x)-IL-EA; The Poly(x)-IL-EA is dried and then immersed in an ion solution containing a lithium salt for ion replacement to obtain a polymer solid electrolyte Li-Poly(x)-IL-EA based on electrospinning technology; The parameters of the electrospinning-high-speed receiving orientation film formation are: voltage 5-25 kV, distance from needle to receiving roller 5-30 cm, solution advancing speed 0.5-8 ml / h, receiving roller speed 100-5000 rpm; The thickness of the Poly(x)-IL-EA is 7-10 μm; The preparation method further comprises the following steps: after the electrospinning-high-speed receiving orientation film formation is completed, the electrospinning is continued by rotating the film to achieve the superposition of electrospun membranes oriented in multiple directions.

2. The method for preparing a polymer solid electrolyte based on electrospinning technology according to claim 1, characterized in that: The amount of the polymer added is 2-50% of the total mass of the polymer and the ionic liquid; and / or, The added amount of the polymer spinning aid is 10-100% of the mass of the polymer.

3. The method for preparing a polymer solid electrolyte based on electrospinning technology according to claim 1, characterized in that: The polymer is one of poly-2,2'-disulfonyl-4,4'-benzidine terephthalamide, sodium alginate and sodium carboxymethyl cellulose; and / or, The polymer spinning aid is at least one of polyethylene glycol, polyethylene oxide, polyvinyl alcohol, polyvinyl pyrrolidone and polyacrylamide; and / or, The ionic liquid is at least one of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide and 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide; and / or, The solvent of the polymer is water, and the solvent of the ionic liquid is water or N,N-dimethylformamide.

4. The method for preparing a polymer solid electrolyte based on electrospinning technology according to claim 1, characterized in that: The mass ratio of the ionic liquid to the solvent is (0.15-0.6):10; and / or, The masses of the solvents in the polymer solution and the ionic liquid solution are equal.

5. The method for preparing a polymer solid electrolyte based on electrospinning technology according to claim 1, characterized in that: The soaking time is 8-48 hours.

6. The method for preparing a polymer solid electrolyte based on electrospinning technology according to claim 1, characterized in that: In the ionic solution containing lithium salt, the molar ratio of lithium salt to ionic liquid is (0.5-1.5):

1.

7. The method for preparing a polymer solid electrolyte based on electrospinning technology according to claim 6, characterized in that: The lithium salt is lithium bis(fluorosulfonyl)imide or lithium bis(trifluoromethanesulfonyl)imide; and / or, The ionic liquid is at least one of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

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