A perfluorinated solid-state polymer electrolyte material and a method of preparation

Abstract

The present application belongs to the field of lithium ion battery materials and electrochemistry, and particularly relates to a perfluorinated solid-state polymer electrolyte material and a preparation method. The present application effectively improves the oxidation resistance of the electrolyte by selecting a polyfluorinated cyclopropene ester as a polymer skeleton, fluorinated groups and a cyclic structure. In addition, the polyfluorinated cyclopropene ester skeleton has excellent compatibility with fluorine-containing solvent molecules, and is also conducive to the formation of an inorganic-rich interface layer on the electrode surface, improving the deposition form of lithium ions. The perfluorinated solid-state polymer electrolyte formed by the polyfluorinated cyclopropene ester polymer skeleton and the fluorine-containing solvent molecules has excellent ionic conductivity (>10 ‑3 S cm ‑1 ) and a high upper limit of oxidation voltage (5.5 V).

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery materials and electrochemistry, specifically relating to a perfluorinated solid polymer electrolyte material and its preparation method. Background Technology

[0002] Polymer electrolytes possess high ionic conductivity, along with good flexibility, processability, and excellent interfacial contact and adhesion, making them key materials for effectively improving the safety, energy density, and cycle life of lithium-ion batteries. However, currently reported polymer electrolytes exhibit poor oxidation resistance, making them difficult to integrate with high-voltage cathode materials. There are two main reasons for this: First, the polymer backbone in polymer solid electrolytes undergoes oxidative decomposition under high voltage. The most commonly used polymer backbone is based on chain acrylates, such as polyethylene glycol diacrylate (PEGDA) and polyethylene glycol dimethacrylate (PEGDMA). The residual C=C double bonds at the ends of conventional chain acrylates after polymerization are easily decomposed under high voltage. The electrochemical window of PEGDA is generally around 4.2V; when combined with NCM high-voltage materials, the electrolyte undergoes severe oxidative decomposition, leading to rapid capacity decay. CN 114725504 A discloses a polymer electrolyte that improves the cycle stability of lithium-ion batteries by introducing functional groups (acrylate phosphate and vinylsiloxane). However, due to the unresolved issue of easy oxidation of the polymer backbone, the upper limit of the battery cycle voltage is only 4.2V. Secondly, conventional carbonate solvents exhibit poor stability at high voltages, easily decomposing to produce a large amount of harmful organic components that reduce the electrolyte-electrode interface performance, ultimately affecting the battery's cycle life. Introducing highly electronegative fluorine groups can effectively improve the electrochemical stability of the electrolyte under high voltage. Therefore, to solve the practical problems of existing polymer electrolytes, it is necessary to develop a polymer electrolyte with a simple preparation process, high ionic conductivity, excellent oxidation resistance, and low interfacial impedance, which can be used with high-voltage cathode materials. Summary of the Invention

[0003] The technical problem to be solved by this invention is to address the poor antioxidant performance and low ionic conductivity of existing polymer electrolytes. This invention provides a perfluorinated solid polymer electrolyte material and its preparation method to improve the antioxidant performance and ionic conductivity of the perfluorinated polymer electrolyte. This material is then applied to batteries with NCM811 as the positive electrode to achieve stable cycling at a high voltage of 4.5V, thereby improving the performance of solid-state batteries.

[0004] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0005] This invention provides a perfluorinated polymer electrolyte material, obtained by initiating polymerization of a polyfluorinated cyclic acrylate monomer in a solvent system containing lithium salt and a fluorinated organic solvent. The structural formula of the polyfluorinated cyclic acrylate monomer is shown in formula (I):

[0006]

[0007] In formula (I): R1 is selected from H, methyl, ethyl or propyl;

[0008] R2 is selected from one of the benzene rings or cyclic groups containing fluorine atoms as shown in formula (II):

[0009]

[0010] According to the above scheme, the polyfluorocyclic acrylate monomer is selected from one or more of 3-(2,4-difluorophenyl) methyl acrylate, 2,4,6-trifluorobenzyl methacrylate, 2,3,5,6-tetrafluorobutyl acrylate, pentafluorobenzyl methacrylate, perfluorocyclohexyl methacrylate, etc.

[0011] According to the above scheme, the fluorinated organic solvent is selected from fluorinated carbonate compounds, and more preferably at least one of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), methyl trifluoroethyl carbonate (FEMC), bis(2,2,2-trifluoroethyl) carbonate (TFEC), and ethyl trifluoroethyl carbonate (ETFEC).

[0012] According to the above scheme, the content of the polyfluorinated cyclic acrylate monomer is 3-15 wt% of the total weight of lithium salt and fluorinated organic solvent.

[0013] This invention provides a method for preparing a perfluorinated polymer electrolyte material. The method involves uniformly stirring components including polyfluorinated cyclic acrylate groups, lithium salts, and fluorinated organic solvents to obtain a precursor solution. This precursor solution undergoes a thermally initiated polymerization reaction under the action of an initiator to obtain a polymer electrolyte containing polyfluorinated cyclic acrylate groups. The method specifically includes the following steps:

[0014] 1) Under an argon protective atmosphere, lithium salt is dissolved in an organic solvent to obtain a mixed solution;

[0015] 2) Add polyfluorinated cyclic acrylate monomers to the mixed solution obtained in step 1).

[0016] 3) Add an initiator to the mixture obtained in step 2) and disperse it evenly to obtain a precursor solution.

[0017] 4) Heat at a certain temperature until the polymeric monomers are completely polymerized to form a polymeric electrolyte. The conditions for the thermally initiated polymerization reaction are: polymerization temperature of 40-80℃ and polymerization time of 6-60 hours.

[0018] According to the above scheme, the lithium salt is selected from lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium tetrafluoroborate. At least one of lithium difluorooxalate borate (LiDFOB) is present, with a concentration of 0.5-3 mol / L.

[0019] According to the above scheme, the initiator is selected from azobisisobutyronitrile (AIBN) and azobisisoheptanenitrile (C... 14 H 24 At least one of N4), comprising 0.3-1 wt% of the total weight of the polyfluorinated cyclic acrylate monomer, lithium salt and fluorinated organic solvent.

[0020] The present invention provides a perfluorinated solid polymer electrolyte prepared by the above preparation method.

[0021] The present invention further provides the application of the above-described perfluorinated polymer electrolyte as an electrolyte material for assembling lithium-ion batteries.

[0022] According to the above scheme, the above assembly method is as follows: following the assembly method of liquid lithium batteries, the obtained precursor solution is added dropwise to the separator, and the battery is assembled with positive and negative electrodes, left to stand, and then heated at a certain temperature until the polymer monomers are completely polymerized and form polymeric electrolyte inside the battery, thus obtaining a perfluorinated solid polymer electrolyte lithium battery. The conditions for the thermally initiated polymerization reaction are: polymerization temperature of 40-80°C and polymerization time of 6-60 hours.

[0023] According to the above scheme, the lithium-ion battery is a Li||NCM811 battery or a LiFePO4||Li battery.

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

[0025] 1. This invention selects polyfluorinated cyclic acrylates as the polymer backbone of the perfluorinated polymer electrolyte. The fluorinated groups and cyclic structure effectively improve the oxidation resistance of conventional acrylates. With the use of fluorinated organic solvents, the upper limit of the electrochemical window of the polymer electrolyte is increased from 4.2V to 5.5V, making acrylate polymer electrolytes suitable for high-voltage applications such as NCM811 cathodes, thus improving the performance of solid-state batteries.

[0026] 2. The polyfluorinated cyclic acrylate backbone provided by this invention exhibits excellent compatibility with fluorinated organic solvent molecules, which is beneficial for forming an inorganic-rich interface layer on the electrode surface and improving the deposition morphology of lithium ions. The perfluorinated solid polymer electrolyte formed by the polyfluorinated cyclic acrylate polymer backbone and fluorinated solvent molecules has excellent ionic conductivity (>10). -3 S cm -1 The material design and preparation of this invention are simple, controllable, and practical, providing a completely new approach for the preparation of perfluorinated polymer electrolytes and related batteries. Attached Figure Description

[0027] Figure 1 This is a comparison of the ionic conductivity of perfluorocyclohexyl methacrylate electrolyte (F-GPE) and PEGDA-based electrolyte (GPE).

[0028] Figure 2 It is the electrochemical window for perfluorocyclohexyl methacrylate electrolytes and PEGDA-based electrolytes.

[0029] Figure 3 The test involved assembling a lithium battery using ternary material NCM811 as the positive electrode and perfluorocyclohexyl methacrylate electrolyte, and performing electrochemical float tests within a voltage range of 4.2V-4.8V.

[0030] Figure 4 The test involved assembling a lithium battery using ternary material NCM811 as the positive electrode and PEGDA-based electrolyte, and conducting electrochemical float tests within a voltage range of 4.2V-4.8V.

[0031] Figure 5 The lithium copper battery is assembled using perfluorocyclohexyl methacrylate-based electrolyte and PEGDA-based electrolyte, and operates at 1 mA cm⁻¹. -2 The lithium deposition morphology and cross-sectional view on the copper foil surface after 5 hours of discharge at a current density.

[0032] Figure 6 This is a lithium battery assembled using lithium iron phosphate (LiFePO4) as the positive electrode, and perfluorocyclohexyl methacrylate-based electrolyte and PEGDA-based electrolyte. It operates at a 1C rate (1C = 170 mAh g) within a voltage range of 2.5V to 4V. -1 The cyclic performance diagram.

[0033] Figure 7 This lithium battery uses ternary material NCM811 as the positive electrode and is assembled with perfluorocyclohexyl methacrylate-based electrolyte and PEGDA-based electrolyte. It operates at a rate of 0.2C (1C = 200mAh g) within a voltage range of 3V to 4.5V. -1 The cyclic performance diagram.

[0034] Figure 8 This lithium battery uses ternary material NCM811 as the positive electrode and perfluorocyclohexyl methacrylate-based electrolyte to assemble a battery, operating at a rate of 0.2C (1C = 200mAh g) within a voltage range of 3V to 4.5V. -1 ) Specific capacity-voltage diagram of the cycle.

[0035] Figure 9 It is the ionic conductivity of a polymer electrolyte (F1-GPE) prepared with a 5 wt% content of perfluorocyclohexyl methacrylate monomer.

[0036] Figure 10 This is a lithium battery assembled using lithium iron phosphate (LiFePO4) as the positive electrode and a polymer electrolyte (F1-GPE) prepared with 5 wt% perfluorocyclohexyl methacrylate monomer. It operates at a 1C rate (1C = 170 mAh g) within a voltage range of 2.5V to 4V. -1 The cyclic performance diagram.

[0037] Figure 11 This lithium battery is assembled using a polymer electrolyte (F1-GPE) prepared with ternary material NCM811 as the positive electrode and 5 wt% perfluorocyclohexyl methacrylate monomer. It operates at a rate of 0.2C (1C = 200 mAh g) within a voltage range of 3V to 4.5V. -1 ) Specific capacity-voltage diagram of the cycle. Detailed Implementation

[0038] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0039] Example 1

[0040] A method for preparing a perfluorinated polymer electrolyte and its application in a solid-state battery, comprising the following steps:

[0041] 1) Weigh 0.5 mL of FEC and 0.5 mL of FEMC solvent and mix them evenly. Add 0.2871 g of LiTFSI (1 M) to the mixture and stir until homogeneous.

[0042] 2) Add 8 wt% of perfluorocyclohexyl methacrylate monomer (total weight of lithium salt and fluorinated organic solvent) to the mixture and stir for 2 hours. Then add 0.3 wt% of initiator AIBN and stir for 30 minutes to obtain the precursor solution.

[0043] 3) Following the assembly method for liquid lithium batteries, the obtained precursor solution was added dropwise to a polypropylene (PP) separator, and the button cell was assembled. The button cell was left to stand for 2 hours, and then heated at 60°C for 12 hours to obtain a perfluorinated polymer electrolyte lithium battery. The perfluorinated polymer electrolyte was named F-GPE.

[0044] Figure 1 This paper compares the ionic conductivity of perfluorocyclohexyl methacrylate (F-GPE) and PEGDA-based electrolyte (GPE). Both F-GPE and PEGDA-based electrolytes were prepared using the same fluorinated solvent, lithium salt, and initiator, under identical synthesis conditions. The volume resistivity of the F-GPE electrolyte (3.2 Ω) is found to be lower than that of the conventional PEGDA-based electrolyte (6.3 Ω), and the calculated ionic conductivity of the F-GPE electrolyte is 3.93 × 10⁻⁶. -3 S / cm, while the ionic conductivity of ordinary PEGDA-based electrolytes is 1.72 × 10⁻⁶. -3 The S / cm ratio indicates that the perfluorocyclohexyl methacrylate-based electrolyte possesses excellent ion transport properties.

[0045] Figure 2 The electrochemical windows of perfluorocyclohexyl methacrylate (F-GPE) and PEGDA-based electrolytes (GPE) are shown. It can be found that the PEGDA-based electrolyte's electrochemical window is significantly increased to 4.6V due to the introduction of the fluorinated solvent, while the perfluorocyclohexyl methacrylate electrolyte's electrochemical window can be increased to 5.5V. This demonstrates the excellent stability of polyfluorocyclohexyl acrylate electrolytes under high voltage conditions.

[0046] Figure 3 and Figure 4 Lithium-ion batteries were assembled using ternary NCM811 as the positive electrode and with polyfluorinated cyclic acrylate (F-GPE) and PEGDA-based electrolytes (GPE), respectively, and electrochemical float tests were conducted within a voltage range of 4.2V–4.8V. This further reflects the high-voltage stability of solid-state electrolytes in practical applications. It was found that the Li||NCM811 battery with perfluorocyclohexylmethacrylate electrolyte maintained a stable leakage current within the 4.2V–4.8V voltage range. In stark contrast, the battery using PEGDA-based electrolyte exhibited a sharp increase and fluctuation in current when charged at a constant voltage to 4.4V. These results further demonstrate that the oxidation stability of the polyfluorinated cyclic acrylate electrolyte is significantly enhanced.

[0047] Figure 5 The lithium copper battery is assembled using polyfluorinated cyclic acrylate electrolyte (F-GPE) and PEGDA-based electrolyte (GPE), and operates at 1 mA cm⁻¹.-2 The lithium deposition morphology and cross-sectional images on the copper foil surface after discharge at a current density for 5 hours are shown. It can be observed that the lithium deposited on the copper foil surface using the perfluorocyclohexyl methacrylate-based electrolyte is densely and uniformly arranged, without obvious needle-like lithium dendrites, indicating that this electrolyte is conducive to the deposition of lithium. + Uniform flux distribution and controlled lithium nucleation ultimately promote uniform Li deposition, exhibiting excellent lithium deposition kinetics and effectively suppressing lithium dendrites. In contrast, copper foil surfaces using PEGDA-based electrolytes exhibited a large number of loose, porous needle-like lithium dendrites, indicating severe side reactions between lithium metal and the electrolyte, resulting in a large amount of dead lithium.

[0048] Figure 6 This lithium battery uses lithium iron phosphate (LiFePO4) as the positive electrode and lithium metal as the negative electrode, and is assembled using polyfluorinated cyclic acrylate electrolyte (F-GPE) and PEGDA-based electrolyte (GPE). It operates at a 1C rate (1C = 170 mAh g) within a voltage range of 2.5V to 4V. -1 The cycling performance graph shows that after using the perfluorocyclohexyl methacrylate-based electrolyte, the initial discharge specific capacity is 138.6 mAh g. -1 It is slightly higher than the initial discharge specific capacity of the PEGDA-based electrolyte, at 127.6 mAh g. -1 Furthermore, the perfluorocyclohexyl methacrylate-based electrolyte exhibits more stable cycling performance.

[0049] Figure 7 This lithium battery uses ternary material NCM811 as the positive electrode and lithium metal as the negative electrode, and is assembled using polyfluorinated cyclic acrylate electrolyte (F-GPE) and PEGDA-based electrolyte (GPE). It operates at a rate of 0.2C (1C = 200mAh g) within a voltage range of 3V to 4.5V. -1 The cycling performance graph shows that the battery using the PEGDA-based electrolyte has an initial discharge specific capacity of 81.1 mAh g. -1 By the 20th cycle, the discharge specific capacity rapidly decreased to 3.1 mAh g. -1 The battery using a polyfluorinated cyclic acrylate electrolyte has an initial discharge specific capacity of 184.3 mAh g. -1 After 20 cycles, the discharge specific capacity is 187.2 mAh g. -1 There is no capacity loss.

[0050] Figure 8 This lithium battery uses ternary material NCM811 as the positive electrode and polyfluorinated cyclic acrylate electrolyte (F-GPE) to assemble a rate of 0.2C (1C = 200mAh g) within a voltage range of 3V to 4.5V. -1The specific capacity-voltage diagram for cycling demonstrates that the perfluorocyclohexyl methacrylate-based electrolyte exhibits excellent high-voltage stability and good compatibility with high-voltage cathode materials.

[0051] Example 2

[0052] A method for preparing a perfluorinated polymer electrolyte and its application in a solid-state battery, comprising the following steps:

[0053] 1) Weigh 0.5 mL of DFEC and 0.5 mL of FEMC solvent and mix them evenly. Add 0.5742 g of LiTFSI (2 M) to the mixture and stir until homogeneous.

[0054] 2) Add 8 wt% of 2,3,5,6-tetrafluorobutyl acrylate monomer (total weight of lithium salt and fluorinated organic solvent) to the mixture and stir for 2 hours. Then add 0.3 wt% of initiator AIBN and stir for 15 minutes to obtain the precursor solution.

[0055] 3) Following the assembly method for liquid lithium batteries, the obtained precursor solution was added dropwise to a polypropylene (PP) separator, and the button cell was assembled. The button cell was left to stand for 2 hours, and then heated at 60°C for 12 hours to finally obtain a perfluorinated solid polymer electrolyte lithium battery.

[0056] Example 3

[0057] A method for preparing a perfluorinated polymer electrolyte and its application in a solid-state battery, comprising the following steps:

[0058] 1) Weigh 1 mL of TFEC solvent, add 0.8613 g of LiTFSI (3 M) to it, and stir until homogeneous.

[0059] 2) Add 10 wt% of 2,4,6-trifluorobenzyl methacrylate monomer (total weight of lithium salt and fluorinated organic solvent) to the mixture and stir for 2 hours. Then add 0.3 wt% of initiator AIBN and stir for 15 minutes to obtain the precursor solution.

[0060] 3) Following the assembly method for liquid lithium batteries, the obtained precursor solution was added dropwise to a polypropylene (PP) separator, and the button cell was assembled. The button cell was left to stand for 2 hours, and then heated at 60°C for 12 hours to finally obtain a perfluorinated solid polymer electrolyte lithium battery.

[0061] Example 4

[0062] A method for preparing a perfluorinated polymer electrolyte and its application in a solid-state battery, comprising the following steps:

[0063] 1) Weigh 1 mL of FEMC solvent and mix it evenly. Add 0.2871 g of LiTFSI (1 M) to the mixture and stir until homogeneous.

[0064] 2) Add 10 wt% (total weight of lithium salt and fluorinated organic solvent) of pentafluorobenzyl methacrylate monomer to the mixture and stir for 2 hours. Then add 0.3 wt% of initiator AIBN and stir for 15 minutes to obtain the precursor solution.

[0065] 3) Following the assembly method for liquid lithium batteries, the obtained precursor solution was added dropwise to a polypropylene (PP) separator, and the button cell was assembled. The button cell was left to stand for 2 hours, and then heated at 60°C for 12 hours to finally obtain a perfluorinated polymer electrolyte lithium battery.

[0066] Example 5

[0067] A method for preparing a perfluorinated polymer electrolyte and its application in a solid-state battery, comprising the following steps:

[0068] 1) Weigh 1 mL of ETFEC solvent and mix it evenly. Add 0.2871 g of LiTFSI to the mixture and stir until homogeneous.

[0069] 2) Add 10 wt% of the total weight of lithium salt and fluorinated organic solvent (pentafluorophenyl acrylate monomer) to the mixture and stir for 2 hours. Then add 0.3 wt% of initiator AIBN and stir for 15 minutes to obtain the precursor solution.

[0070] 3) Following the assembly method for liquid lithium batteries, the obtained precursor solution was added dropwise to a polypropylene (PP) separator, and the button cell was assembled. The button cell was left to stand for 2 hours, and then heated at 60°C for 12 hours to finally obtain a perfluorinated polymer electrolyte lithium battery.

[0071] The inventors conducted a comparative analysis of the ionic conductivity and electrochemical window of different polyfluorinated cyclic acrylate polymer electrolytes prepared in Examples 1-5, and the results are shown in Table 1.

[0072] Table 1. Ionic conductivity and electrochemical window of polyfluorinated cyclic acrylate polymer electrolytes

[0073]

[0074] It can be seen that different polyfluorinated cyclic acrylate polymer electrolytes all exhibit excellent ionic conductivity (>10). -3 Scm -1The high upper limit of antioxidant voltage (>5.0V) indicates that the use of polyfluorinated cyclic acrylates as the polymer backbone, along with the fluorinated groups and cyclic structure, effectively improves the antioxidant properties of the electrolyte. Furthermore, the polyfluorinated cyclic acrylate backbone exhibits excellent compatibility with fluorinated solvent molecules and facilitates the formation of an inorganic-rich interfacial layer on the electrode surface, enabling rapid ion migration.

[0075] Example 6

[0076] A method for preparing a perfluorinated polymer electrolyte and its application in a solid-state battery, comprising the following steps:

[0077] 1) Weigh 0.5 mL of DFEC and 0.5 mL of ETFEC solvent and mix them evenly. Add 0.2871 g of LiDFOB (1 M) to the mixture and stir until homogeneous.

[0078] 2) Add 8 wt% of perfluorocyclohexyl methacrylate monomer (total weight of lithium salt and fluorinated organic solvent) to the mixture and stir for 4 hours. Then add 1 wt% of azobisisobutyronitrile (C... 14 H 24 N4) initiator, and after stirring for 30 min, a precursor solution is obtained.

[0079] 3) Following the assembly method for liquid lithium batteries, the obtained precursor solution was added dropwise to a polypropylene (PP) separator, and the button cell was assembled. The button cell was left to stand for 2 hours, and then heated at 60°C for 30 hours to finally obtain a perfluorinated polymer electrolyte lithium battery.

[0080] Example 7

[0081] A method for preparing a perfluorinated polymer electrolyte and its application in a solid-state battery, comprising the following steps:

[0082] 1) Weigh 1 mL of FEC solvent and mix it evenly. Add 0.2871 g of LiFSI (1 M) to the mixture and stir until homogeneous.

[0083] 2) Add 9 wt% (w / w) of pentafluorobenzyl methacrylate monomer (total weight of lithium salt and fluorinated organic solvent) to the mixture and stir for 2 hours. Then add 0.3 wt% of initiator AIBN and stir for 20 minutes to obtain the precursor solution.

[0084] 3) Following the assembly method for liquid lithium batteries, the obtained precursor solution was added dropwise to a polypropylene (PP) separator, and the button cell was assembled. The button cell was left to stand for 1 hour, and then heated at 80°C for 24 hours to finally obtain a perfluorinated polymer electrolyte lithium battery.

[0085] Example 8

[0086] A method for preparing a perfluorinated polymer electrolyte and its application in a solid-state battery, comprising the following steps:

[0087] 1) Weigh out 0.5 mL of FEC and 0.5 mL of ETFEC solvent and mix them thoroughly. Add 0.2871 g of the mixture to the mixture. (1M), stir well.

[0088] 2) Add 8 wt% (total weight of lithium salt and fluorinated organic solvent) of 2,3,5,6-tetrafluorobutyl acrylate monomer to the mixture and stir for 2 hours. Then add 0.8 wt% of azobisisobutyronitrile (C... 14 H 24 N4) initiator, and after stirring for 30 min, a precursor solution is obtained.

[0089] 3) Following the assembly method for liquid lithium batteries, the obtained precursor solution was added dropwise to a polypropylene (PP) separator, and the button cell was assembled. The button cell was left to stand for 2 hours, and then heated at 70°C for 24 hours to finally obtain a perfluorinated solid polymer electrolyte lithium battery.

[0090] Example 9

[0091] A method for preparing a perfluorinated polymer electrolyte and its application in a solid-state battery, comprising the following steps:

[0092] 1) Weigh 0.5 mL of FEC and 0.5 mL of FEMC solvent and mix them evenly. Add 0.2871 g of LiFSI (1 M) to the mixture and stir until homogeneous.

[0093] 2) Add 10 wt% of 3-(2,4-difluorophenyl)acrylate methyl acrylate monomer (total weight of lithium salt and fluorinated organic solvent) to the mixture and stir for 2 hours. Then add 0.5 wt% of initiator AIBN and stir for 15 minutes to obtain the precursor solution.

[0094] 3) Following the assembly method for liquid lithium batteries, the obtained precursor solution was added dropwise to a polypropylene (PP) separator, and the button cell was assembled. The button cell was left to stand for 2 hours, and then heated at 60°C for 36 hours to finally obtain a perfluorinated solid polymer electrolyte lithium battery.

[0095] Example 10

[0096] A method for preparing a perfluorinated polymer electrolyte and its application in a solid-state battery, comprising the following steps:

[0097] 1) Weigh 0.5 mL of FEC and 0.5 mL of FEMC solvent and mix them evenly. Add 0.2871 g of LiTFSI (1 M) to the mixture and stir until homogeneous.

[0098] 2) Add 5 wt% of perfluorocyclohexyl methacrylate monomer (total weight of lithium salt and fluorinated organic solvent) to the mixture and stir for 2 hours. Then add 0.3 wt% of initiator AIBN and stir for 30 minutes to obtain the precursor solution.

[0099] 3) Following the assembly method for liquid lithium batteries, the obtained precursor solution was added dropwise to a polypropylene (PP) separator, and the button cell was assembled. The button cell was left to stand for 2 hours, and then heated at 60°C for 12 hours to obtain a perfluorinated polymer electrolyte lithium battery. This perfluorinated polymer electrolyte was named F1-GPE.

[0100] Figure 9 This is the ionic conductivity of a polymer electrolyte (F1-GPE) prepared from a 5 wt% perfluorocyclohexyl methacrylate monomer. The calculated ionic conductivity of the perfluorocyclohexyl methacrylate-based electrolyte is 1.63 × 10⁻⁶. -3 The S / cm ratio indicates that the perfluorocyclohexyl methacrylate-based electrolyte has excellent ion transport performance.

[0101] Figure 10 This is a lithium battery assembled using lithium iron phosphate (LiFePO4) as the positive electrode and a polymer electrolyte (F1-GPE) prepared with 5 wt% perfluorocyclohexyl methacrylate monomer. It operates at a 1C rate (1C = 170 mAh g) within a voltage range of 2.5V to 4V. -1 The cycling performance graph shows that after using the perfluorocyclohexyl methacrylate-based electrolyte, the initial discharge specific capacity is 132.5 mAh g. -1 After 20 cycles, the discharge specific capacity is 129.2 mAh g. -1 The perfluorocyclohexyl methacrylate-based electrolyte exhibits good cyclic stability.

[0102] Figure 11 This lithium battery is assembled using a polymer electrolyte (F1-GPE) prepared with ternary material NCM811 as the positive electrode and 5 wt% perfluorocyclohexyl methacrylate monomer. It operates at a rate of 0.2C (1C = 200 mAh g) within a voltage range of 3V to 4.5V. -1 The specific capacity-voltage plot shows that after using the perfluorocyclohexyl methacrylate-based electrolyte, the initial discharge specific capacity is 190.3 mAh g. -1 After 20 cycles, the discharge specific capacity is 188.2 mAh g. -1The perfluorocyclohexyl methacrylate-based electrolyte exhibits good cycle stability and its performance is similar to that of the perfluorocyclohexyl methacrylate-based polymer electrolyte (F-GPE) with a total weight of 8 wt% lithium salt and fluorinated organic solvent used in Example 1, demonstrating good uniformity.

[0103] Comparative Example

[0104] This describes a method for preparing and applying polymer electrolytes and solid-state batteries using PEGDA polymer monomers. As a comparative example, the preparation is carried out through the following steps:

[0105] 1) Weigh 0.5 mL of FEC and 0.5 mL of FEMC solvent and mix them evenly. Add 0.2871 g of LiTFSI (1 M) to the mixture and stir until homogeneous.

[0106] 2) Add 8 wt% of lithium salt and fluorinated organic solvent (total weight of PEGDA monomer) to the mixture and stir for 2 hours. Then add 0.3 wt% of initiator AIBN and stir for 30 minutes to obtain the precursor solution.

[0107] 3) Following the assembly method for liquid lithium batteries, the obtained precursor solution was added dropwise to a polypropylene (PP) separator, and the button cell was assembled. The button cell was left to stand for 2 hours, and then heated at 60°C for 12 hours to finally obtain a perfluorinated polymer electrolyte lithium battery.

[0108] The above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations, and any obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A Li||NCM811 or LiFePO4||Li lithium-ion battery, characterized in that: Using ternary material NCM811 as the positive electrode and lithium metal as the negative electrode, or using lithium iron phosphate (LiFePO4) as the positive electrode and lithium metal as the negative electrode, the electrolyte is obtained by initiating the polymerization of polyfluorinated cyclic acrylate monomers in a solvent system containing lithium salt and fluorinated organic solvent, thereby forming a polymerized electrolyte inside the battery. The content of the polyfluorinated cyclic acrylate monomers is 3-15 wt% of the total weight of lithium salt and fluorinated organic solvent. The monomers are completely polymerized and form a polymerized electrolyte inside the battery. The polyfluorinated cyclic acrylate monomers are any one of the compounds of the general formula shown in formula (I), or 2,4,6-trifluorobenzyl methacrylate or pentafluorobenzyl methacrylate. （I） In formula (I): R1 is selected from H, methyl, ethyl or propyl; R2 is selected from one of the benzene rings or cyclic groups containing fluorine atoms as shown in formula (II): （Ⅱ） The fluorinated organic solvent is selected from fluorinated carbonate compounds, specifically at least one of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), methyl trifluoroethyl carbonate (FEMC), bis(2,2,2-trifluoroethyl) carbonate (TFEC), and ethyl trifluoroethyl carbonate (ETFEC).

2. The Li||NCM811 or LiFePO4||Li lithium-ion battery according to claim 1, characterized in that: The polyfluorocycloacrylate monomer is selected from one or more of 2,4,6-trifluorobenzyl methacrylate, pentafluorobenzyl methacrylate, and perfluorocyclohexyl methacrylate.

3. The assembly method of a lithium-ion battery according to claim 1, characterized in that, According to the assembly method of liquid lithium battery, a precursor solution containing polyfluorinated cyclic acrylate groups is added dropwise to the separator, and the battery is assembled with positive and negative electrodes. After standing, it is heated at a certain temperature until the polymer monomers are completely polymerized and form polymeric electrolyte inside the battery, thus obtaining a perfluorinated solid polymer electrolyte lithium battery. The conditions for the thermally initiated polymerization reaction are: polymerization temperature of 40-80℃ and polymerization time of 6-60 hours.

4. The assembly method according to claim 3, characterized in that: A precursor solution containing polyfluorinated cyclic acrylate groups is obtained by uniformly stirring the components including polyfluorinated cyclic acrylate groups, lithium salt, and fluorinated organic solvent. This precursor solution undergoes thermally initiated polymerization under the action of an initiator to obtain a polymer electrolyte containing polyfluorinated cyclic acrylate groups. The specific steps include: 1) Under an argon protective atmosphere, lithium salt is dissolved in a fluorinated organic solvent to obtain a mixed solution; 2) Add polyfluorinated cyclic acrylate monomers to the mixed solution obtained in step 1); 3) Add an initiator to the mixture obtained in step 2), and disperse it evenly to obtain a precursor solution; 4) Heat at a certain temperature until the monomers are completely polymerized to form a polymeric electrolyte. The conditions for the thermally initiated polymerization reaction are: polymerization temperature of 40-80℃ and polymerization time of 6-60 hours.

5. The assembly method according to claim 4, characterized in that: The lithium salt is selected from at least one of lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), and lithium difluorooxalate borate (LiDFOB), with a concentration of 0.5-3 mol / L.

6. The assembly method according to claim 4, characterized in that: The initiator is selected from azobisisobutyronitrile (AIBN) and azobisisoheptanenitrile (C... 14 H 24 At least one of N4), comprising 0.3-1 wt% of the total weight of the polyfluorinated cyclic acrylate monomer, lithium salt and fluorinated organic solvent.

Images