A solid-state lithium-ion battery polymer electrolyte based on p-fluorocinnamic acid

Abstract

The present invention belongs to the fields of synthesis of high molecular compounds and lithium-ion batteries, and discloses a solid-state lithium-ion battery polymer electrolyte based on p-fluorocinnamic acid. The preparation method of this electrolyte is to first carry out a polymerization reaction between p-fluorocinnamic acid monomers and carbonate-based monomers, and then blend the prepared product with a lithium salt and a polymer matrix. After heating and stirring, a transparent and uniform solution is obtained. The solution is coated on a polytetrafluoroethylene plate and dried in a vacuum oven, and finally a solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid is obtained. The polymer electrolyte membrane prepared by the present invention has high ionic conductivity and an electrochemical window, and has a significant effect on improving the performance of solid-state lithium-ion batteries.

Description

Technical Field

[0001] The present invention belongs to the fields of synthesis of polymer compounds and lithium-ion batteries, and particularly relates to a solid-state lithium-ion battery polymer electrolyte based on p-fluorocinnamic acid. Background Art

[0002] Currently, with the continuous growth of demands for portable consumer electronic devices, energy-powered vehicles, large-scale grid energy storage systems, etc., the market has put forward higher requirements for the performance of lithium-ion batteries (LIBs), such as energy density, safety, cycle life, etc. However, the energy density of traditional lithium-ion batteries has approached the limit and it is difficult to achieve a breakthrough; moreover, the organic liquid electrolytes used in traditional commercial lithium-ion batteries have poor thermal stability and high flammability, which may cause catastrophic fires or even explosions and other safety problems. To solve the above problems, all-solid-state lithium-ion batteries (ASSLIBs) have developed rapidly in recent years. ASSLIBs use non-flammable or less flammable solid electrolytes (SSEs) to replace the organic electrolytes in the traditional system, which helps to solve the intrinsic safety of lithium batteries. Moreover, due to the more compact structure, ASSLIBs can have a higher energy density.

[0003] As the core component of ASSLIBs, SSEs play a dual role of both ionic conduction and blocking the contact between the positive and negative electrodes, and are the key factors affecting the performance of ASSLIBs. Solid electrolytes are generally divided into two categories: inorganic solid electrolytes (ISEs) and polymer solid electrolytes (SPEs). ISEs usually have excellent ionic conductivity and a wide electrochemical window, but they have defects such as easy brittle fracture and poor interfacial compatibility, which seriously hinder their practical applications. In contrast, although the basic electrochemical properties of SPEs are not as good as those of ISEs, due to their good flexibility, easy film formation, excellent interfacial contact, and advantages in battery integration and processing costs, they are considered to have great industrial application prospects.

[0004] SPEs generally conduct lithium ions through the movement of polymer segments. However, at room temperature, polymer materials generally have a high degree of crystallinity, which restricts the free movement of segments and the coordination migration of Li + , so the room-temperature ionic conductivity of SPEs is generally low (<10 -4 S cm -1 ). In addition, SPEs usually have weak antioxidant properties and cannot match high-voltage positive electrodes; the interfacial stability is also relatively poor, and it is difficult to resist interfacial side reactions and lithium dendrite growth problems. Therefore, over the years, researchers have continuously designed and optimized SPEs through methods and techniques such as functional group regulation, structural optimization, interfacial engineering, and new preparation processes to improve the ionic conductivity, electrochemical window, interfacial stability, cycle life, and stability of polymer electrolytes. Summary of the Invention

[0005] To solve the above problems, the present invention provides a solid-state lithium-ion battery polymer electrolyte based on p-fluorocinnamic acid, aiming to improve the ionic conductivity, electrochemical window, and interfacial stability of the polymer electrolyte, thereby improving the cycling performance of the solid-state lithium-ion battery constructed based on it.

[0006] The technical solution adopted by the present invention is as follows:

[0007] The present invention first provides a preparation method of a solid-state lithium-ion battery polymer electrolyte based on p-fluorocinnamic acid, including the following steps:

[0008] (1) Add p-fluorocinnamic acid to a polar aprotic organic solvent, heat and stir until dissolved to obtain solution A;

[0009] (2) Add a carbonate-based monomer and an initiator to solution A, heat and stir to react to obtain solution B;

[0010] (3) Add a lithium salt to solution B, heat and stir until dissolved to obtain solution C;

[0011] (4) Add a polymer matrix to solution C, heat and stir until dissolved to obtain solution D;

[0012] (5) Coat the solution D on a polytetrafluoroethylene plate, and vacuum dry the solvent to obtain a solid-state lithium-ion battery polymer electrolyte based on p-fluorocinnamic acid.

[0013] Preferably, steps (1) to (4) are carried out in an atmospheric-pressure reactor protected by an inert gas atmosphere, the heating temperature is 40-80 °C, and the heating and stirring reaction time in step (2) is 12-48 h.

[0014] Preferably: the mass ratio of p-fluorocinnamic acid to the polar aprotic organic solvent is 1:(10-100); the molar ratio of p-fluorocinnamic acid to the carbonate-based monomer is 1:(1-30), and the addition amount of the initiator is 0.05%-1% of the total mass of p-fluorocinnamic acid and the carbonate-based monomer; the molar ratio of p-fluorocinnamic acid to the lithium salt is 1:(1-10); the molar ratio of p-fluorocinnamic acid to the polymer matrix is 1:(1-10).

[0015] Preferably, in step (1), the polar aprotic organic solvent is at least one of acetonitrile, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, and dichloromethane.

[0016] Preferably, in step (2), the carbonate-based monomer is at least one of vinylene carbonate, ethylene vinylene carbonate, ethyl methacrylate, and methyl acrylate.

[0017] Preferably, in step (3), the lithium salt is at least one of lithium nitrate, lithium perchlorate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalato)borate, lithium bis(trifluoromethanesulfonyl)imide, lithium difluoro(oxalato)borate, and lithium bis(fluorosulfonyl)imide.

[0018] Preferably, in step (4), the polymer matrix is at least one of polyethylene oxide, polyacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride, and their copolymers.

[0019] The present invention also provides a solid-state lithium-ion battery polymer electrolyte based on p-fluorocinnamic acid, and the solid-state lithium-ion battery polymer electrolyte based on p-fluorocinnamic acid is prepared by the above preparation method.

[0020] The present invention further provides a solid-state lithium-ion battery, which contains the above solid-state polymer electrolyte based on p-fluorocinnamic acid. The preparation method of the solid-state lithium-ion battery includes the following steps:

[0021] (1) Grind the positive electrode active material, carbon black, and polyvinylidene fluoride evenly in a ratio of 8:1:1, then disperse them in N-methylpyrrolidone solvent to obtain a paste-like slurry, and coat it on an aluminum foil using a scraper and dry it to obtain a positive electrode sheet;

[0022] (2) Use a lithium metal sheet as the negative electrode, and prepare a solid-state lithium-ion battery by combining the above positive electrode sheet with the solid-state polymer electrolyte based on p-fluorocinnamic acid;

[0023] Preferably, in step (1), the positive electrode active material is at least one of lithium cobaltate, lithium manganate, lithium iron phosphate, and ternary material LiNi x Co y Mn z O2 (x + y + z = 1).

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1. The present invention selects p-fluorocinnamic acid as one of the monomers to synthesize the solid-state lithium-ion battery polymer electrolyte. The p-fluorocinnamic acid introduces carboxyl groups, fluorine atoms, and benzene rings into the electrolyte system. The carboxyl groups can promote the dissociation of lithium ions and anions in the lithium salt through electrostatic attraction, increasing the free lithium ions. The highly electronegative fluorine atoms can enhance the chemical stability and antioxidant properties of the polymer, reduce the decomposition of the electrolyte at high voltages, and improve the interfacial stability. The benzene rings can improve the mechanical properties of the electrolyte membrane and inhibit the growth of lithium dendrites.

[0026] 2. The p-fluorocinnamic acid selected in the present invention contains conjugated double bonds, which can undergo a free radical polymerization reaction with the carbonate monomer under the action of an initiator to form a novel polymer structure. The rigid fluorophenyl group (p-fluorocinnamic acid) combines with the flexible carbonate chain segment to balance mechanical strength and flexibility.

[0027] 3. The solid-state lithium-ion battery polymer electrolyte based on p-fluorocinnamic acid provided by the present invention has excellent performance. It not only has a high room temperature ionic conductivity (8.1×10 -4 S cm -1 ), but also can significantly improve the capacity and cycle life of the solid-state lithium-ion battery after being applied to the solid-state lithium-ion battery. Moreover, its preparation method is convenient, and the existing battery production process and production equipment can be utilized without increasing equipment investment, having good industrialization prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 FIG. is the infrared absorption spectrum of the solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid prepared in Example 1;

[0029] Figure 2 FIG. is the surface SEM image of the solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid prepared in Example 1;

[0030] Figure 3 FIG. is the surface SEM image of the solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid prepared in Example 2;

[0031] Figure 4 FIG. is the surface SEM image of the solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid prepared in Comparative Example 1;

[0032] Figure 5 FIG. is the impedance diagram of the solid-state lithium-ion battery polymer electrolyte membranes based on p-fluorocinnamic acid prepared in Example 1, Example 2 and Comparative Example 1;

[0033] Figure 6 The lithium ion transference number diagram of the solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid prepared in Example 1;

[0034] Figure 7 FIG. is the electrochemical window diagram of the solid-state lithium-ion battery polymer electrolyte membranes based on p-fluorocinnamic acid prepared in Example 1, Example 2 and Comparative Example 1;

[0035] Figure 8 FIG. is the lithium stability diagram of the solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid prepared in Example 1;

[0036] Figure 9Cycling performance graph of the lithium iron phosphate half-cell assembled with the solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid of Example 1;

[0037] Figure 10 Assembled with the solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid of Example 1 is LiNi 0.88 Co 0.06 Mn 0.06 O2 half-cell cycling performance graph. Detailed implementation mode

[0038] The technical solution of the present invention will be described in detail below in conjunction with the drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0039] Example 1

[0040] This example provides a solid-state lithium-ion battery polymer electrolyte based on p-fluorocinnamic acid, and its specific preparation steps are as follows:

[0041] (1) Under the protection of an argon atmosphere, 0.2 g (1.2 mmol) of p-fluorocinnamic acid was dissolved in 8 mL of N-methylpyrrolidone, and heated and stirred at 60 °C until dissolved to obtain solution A.

[0042] (2) Under the protection of an argon atmosphere, 2 g (24 mmol) of vinylene carbonate monomer and 0.02 g of initiator azobisisobutyronitrile were added to solution A, and heated and stirred at 60 °C for 24 h to obtain solution B.

[0043] (3) Under the protection of an argon atmosphere, 1 g (3.6 mmol) of lithium bis(trifluoromethanesulfonyl)imide was added to solution B, and heated and stirred at 60 °C until dissolved to obtain solution C.

[0044] (4) Under the protection of an argon atmosphere, 1.2 g (5.4 mmol) of poly(vinylidene fluoride-co-hexafluoropropylene) was added to solution C, and heated and stirred at 60 °C for 24 h to obtain solution D.

[0045] (5) Solution D was coated on a polytetrafluoroethylene plate, and the solvent was evaporated at 75 °C in a vacuum oven for 24 h to obtain a solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid. The obtained electrolyte membrane was cut into discs with a diameter of 16 mm.

[0046] To test the performance of the obtained polymer electrolyte membrane, the following batteries were further assembled in this example:

[0047] Lithium symmetric battery, and its specific preparation steps are as follows: Assemble the battery negative electrode housing, lithium metal sheet, solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid prepared in this embodiment, lithium metal sheet, gasket, shrapnel, and battery positive electrode housing in sequence. Put the whole battery into a battery sealer and press it to obtain a CR2032 button battery.

[0048] Solid-state lithium-ion battery, and its specific preparation steps are as follows: Assemble the battery negative electrode housing, lithium metal sheet, solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid prepared in this embodiment, positive electrode sheet, gasket, shrapnel, and battery positive electrode housing in sequence. Put the whole battery into a battery sealer and press it to obtain a CR2032 button battery. The preparation method of the positive electrode sheet among them is: Grind lithium iron phosphate or LiNi 0.88 Co 0.06 Mn 0.06 O2 powder, carbon black, and polyvinylidene fluoride in a mass ratio of 8:1:1, disperse them in N-methylpyrrolidone and stir into a slurry. Then coat the slurry on aluminum foil and place it in a blast drying oven to dry at 80 °C for 16 h. Cut the dried electrode material into round pieces with a diameter of 12 mm.

[0049] Example 2

[0050] This example provides a solid-state lithium-ion battery polymer electrolyte based on p-fluorocinnamic acid, and its specific preparation steps are as follows:

[0051] (1) Under the protection of an argon atmosphere, dissolve 0.2 g (1.2 mmol) of p-fluorocinnamic acid in 8 mL of N-methylpyrrolidone, and heat and stir at 60 °C until dissolved to obtain solution A.

[0052] (2) Under the protection of an argon atmosphere, add 3 g (36 mmol) of vinylene carbonate monomer and 0.02 g of initiator azobisisobutyronitrile to solution A, and heat and stir at 60 °C for 24 h to obtain solution B.

[0053] (3) Under the protection of an argon atmosphere, add 1 g (3.6 mmol) of lithium bis(trifluoromethanesulfonyl)imide to solution B, and heat and stir at 60 °C until dissolved to obtain solution C.

[0054] (4) Under the protection of an argon atmosphere, add 1.2 g (5.4 mmol) of poly(vinylidene fluoride-co-hexafluoropropylene) to solution C, and heat and stir at 60 °C for 24 h to obtain solution D.

[0055] (5) Coating solution D onto a polytetrafluoroethylene plate, heating and evaporating the solvent at 75 °C in a vacuum oven for 24 h to obtain a solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid. Cutting the obtained electrolyte membrane into circular pieces with a diameter of 16 mm.

[0056] Assembling the lithium symmetric battery and the solid-state lithium-ion battery in the same method as in Example 1.

[0057] Comparative Example 1

[0058] This comparative example provides a solid-state lithium-ion battery polymer electrolyte based on p-fluorocinnamic acid, and its specific preparation steps are as follows:

[0059] (1) Under the protection of an argon atmosphere, dissolving 0.2 g (1.2 mmol) of p-fluorocinnamic acid in 8 mL of N-methylpyrrolidone, heating and stirring at 60 °C until dissolved to obtain solution A.

[0060] (2) Under the protection of an argon atmosphere, adding 4 g (48 mmol) of vinylene carbonate monomer and 0.02 g of initiator azobisisobutyronitrile to solution A, heating and stirring at 60 °C for 24 h to obtain solution B.

[0061] (3) Under the protection of an argon atmosphere, adding 1 g (3.6 mmol) of lithium bis(trifluoromethanesulfonyl)imide to solution B, heating and stirring at 60 °C until dissolved to obtain solution C.

[0062] (4) Under the protection of an argon atmosphere, adding 1.2 g (5.4 mmol) of poly(vinylidene fluoride-co-hexafluoropropylene) to solution C, heating and stirring at 60 °C for 24 h to obtain solution D.

[0063] (5) Coating solution D onto a polytetrafluoroethylene plate, heating and evaporating the solvent at 75 °C in a vacuum oven for 24 h to obtain a solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid. Cutting the obtained electrolyte membrane into circular pieces with a diameter of 16 mm.

[0064] Assembling the lithium symmetric battery and the solid-state lithium-ion battery in the same method as in Example 1.

[0065] Figure 1 is the infrared absorption spectrum of the solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid prepared in Example 1. Different characteristic peaks correspond to the structure of the target polymer, proving that various substances have been successfully introduced. Among them, the characteristic peaks corresponding to Ar-F, Ar-H, and C=O indicate that p-fluorocinnamic acid introduces fluorine atoms, benzene rings, and carboxyl groups into the electrolyte system. There is no characteristic peak corresponding to carbon-carbon double bonds (C=C) in the infrared absorption spectrum, indicating that the double bonds of the two monomers have undergone a polymerization reaction.

[0066] Figure 2 Figure SEM of the surface of the solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid prepared in Example 1. It can be seen that the surface of the electrolyte is smooth and dense, which is beneficial to the good interfacial contact between the electrolyte membrane and the electrode.

[0067] Figure 3 Figure SEM of the surface of the solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid prepared in Example 2. It can be seen that the smoothness of the electrolyte surface decreases slightly compared with that in Example 1, which will reduce the interfacial stability.

[0068] Figure 4 Figure SEM of the surface of the solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid prepared in Comparative Example 1. It can be seen that the surface of the electrolyte is uneven, which will result in poor interfacial stability.

[0069] Figure 5 Figure of the impedance of the solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid prepared in Example 1, Example 2 and Comparative Example 1. According to Figure 5 the data, the room temperature ionic conductivity of the polymer electrolyte membrane prepared in Example 1 can be calculated as 8.1×10 -4 S cm -1 , the room temperature ionic conductivity of the polymer electrolyte membrane prepared in Example 2 is 7.1×10 -4 S cm -1 , and the room temperature ionic conductivity of the polymer electrolyte membrane prepared in Comparative Example 1 is 3.5×10 -4 Scm -1 .

[0070] (1)

[0071] In the formula: σ is the ionic conductivity, with the unit of S cm -1 ; l is the thickness of the electrolyte membrane, with the unit of cm; R is the bulk impedance of the electrolyte membrane, with the unit of Ω; S is the area of the electrolyte membrane, with the unit of cm 2 .

[0072] Figure 6 Figure of the lithium ion transference number of the solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid prepared in Example 1. According to Figure 6 the data, the room temperature lithium ion transference number of the polymer electrolyte membrane prepared in Example 1 can be calculated as 0.69, indicating that most of the lithium ions in the lithium salt dissociate from the anions, which is beneficial to improving ion transport.

[0073] (2)

[0074] Wherein: is the lithium ion transference number; Δ V is the polarization voltage, set to 0.01 V; I 0 and I S are the initial current and the stable current, with the unit of A; R 0 and R S are the interfacial impedance before and after battery polarization, with the unit of Ω. I 0 and I S 、R 0 and R S can all be obtained from Figure 6 therein.

[0075] Figure 7 is the electrochemical window diagram of the solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid prepared in Example 1, Example 2 and Comparative Example 1. It can be seen that the electrochemical window of the polymer electrolyte membrane prepared in Example 1 is 5.40 V, the electrochemical window of the polymer electrolyte membrane prepared in Example 2 is 5.25 V, and the electrochemical window of the polymer electrolyte membrane prepared in Comparative Example 1 is 4.50 V. It shows that the electrolyte membrane not only adapts to the lithium iron phosphate cathode, but also can adapt to high-voltage cathodes such as LiNi 0.88 Co 0.06 Mn 0.06 O2.

[0076] Figure 8 is the lithium stability diagram of the solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid prepared in Example 1. The current density is 0.2 mA / cm 2 . The relatively stable voltage value distribution and the deposition / stripping behavior of 1200 h show good lithium stability of the electrolyte membrane. It shows that the electrolyte membrane has good interfacial stability with lithium metal, which is beneficial to improving the cycle performance of lithium-ion batteries.

[0077] Figure 9 is the cycle performance diagram of the lithium iron phosphate half-cell assembled with the solid-state lithium-ion battery polymer electrolyte membrane based on p-fluorocinnamic acid in Example 1. Through cyclic charge and discharge tests, the working voltage is 2.8 - 3.6 V, the discharge specific capacity is about 165 mAh / g at 1.0 C, and the coulombic efficiency is about 100%.

[0078] Figure 10The LiNi 0.88 Co 0.06 Mn 0.06 O2 half-cell cycle performance graph assembled from the solid-state lithium-ion battery polymer electrolyte membrane of Example 1. Through cyclic charge and discharge tests, the working voltage is 2.5 - 4.3 V, the discharge specific capacity is about 210 mAh / g at 0.2 C, and the coulombic efficiency is about 90%.

[0079] The parts not elaborated in detail in the present invention belong to the well-known technologies of those skilled in the art. The above-described embodiments are only descriptions of the preferred embodiments of the present invention. The preferred embodiments do not elaborate all the details and do not limit the invention to the specific embodiments described. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should fall within the protection scope determined by the present invention.

Claims

1. A method for preparing a solid-state lithium-ion battery polymer electrolyte based on p-fluorocinnamic acid, characterized in that: The steps include: (1) adding p-fluorocinnamic acid to a polar aprotic organic solvent, heating and stirring until dissolved, to obtain solution A; (2) adding a carbonate monomer and an initiator to solution A, heating and stirring to react, to obtain solution B, wherein the molar ratio of p-fluorocinnamic acid to the carbonate monomer is 1:1-30; (3) Add lithium salt to solution B, heat and stir until dissolved, to obtain solution C; (4) Add the polymer matrix to solution C, heat and stir until dissolved, and obtain solution D; (5) The solution D is coated on a polytetrafluoroethylene plate, and the solvent is dried under vacuum to obtain a solid-state lithium-ion battery polymer electrolyte based on p-fluorocinnamic acid.

2. The method for preparing a solid-state lithium-ion battery polymer electrolyte based on p-fluorocinnamic acid according to claim 1, characterized in that: Steps (1) to (4) are carried out in a normal pressure reactor protected by an inert gas atmosphere, the heating temperature is 40-80°C, and the heating and stirring reaction time in step (2) is 12-48 hours.

3. The method for preparing a solid-state lithium-ion battery polymer electrolyte based on p-fluorocinnamic acid according to claim 1, characterized in that: The mass ratio of p-fluorocinnamic acid to polar aprotic organic solvent is 1:10-100; the added amount of the initiator is 0.05%-1% of the total mass of p-fluorocinnamic acid and carbonate monomer; the molar ratio of p-fluorocinnamic acid to lithium salt is 1:1-10; and the molar ratio of p-fluorocinnamic acid to polymer matrix is ​​1:1-10.

4. The method according to claim 1, characterized in that: In step (1), the polar aprotic organic solvent is at least one of acetonitrile, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran and dichloromethane.

5. The method according to claim 1, characterized in that In step (2), the carbonate-based monomer is at least one of vinylene carbonate and vinyl ethylene carbonate.

6. The method according to claim 1, characterized in that In step (3), the lithium salt is at least one of lithium nitrate, lithium perchlorate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalatoborate), lithium bis(trifluoromethanesulfonylimide), lithium difluorooxalatoborate and lithium bis(fluorosulfonylimide).

7. The method according to claim 1, characterized in that In step (4), the polymer matrix is ​​at least one of polyethylene oxide, polyacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride and copolymers thereof.

8. A solid-state lithium-ion battery polymer electrolyte based on p-fluorocinnamic acid, characterized in that: The solid-state lithium-ion battery polymer electrolyte based on p-fluorocinnamic acid is prepared by the preparation method described in any one of claims 1 to 7.

9. A solid-state lithium-ion battery, characterized in that: A solid-state lithium-ion battery polymer electrolyte based on p-fluorocinnamic acid as claimed in claim 8.

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