A ternary copolymer fluorine-containing acrylate gel polymer electrolyte, a preparation method and application thereof

Abstract

This invention provides a ternary copolymer fluorinated acrylate gel polymer electrolyte, its preparation method, and its applications. The invention employs three acrylate monomers with high monomer conversion rates and no ether groups for copolymerization. The monomer conversion rate is greater than 99%, avoiding the influence of residual monomers on the electrochemical performance of the battery and improving the oxidation resistance of the gel polymer electrolyte system. Furthermore, the ethylene carbonate and alkyl carbonate groups contained in the monomers of this invention have structures similar to solvent molecules in commonly used electrolytes. Utilizing the non-covalent interactions between these groups and solvent molecules, solvent molecules can be better immobilized in the polymer network, forming a uniform network structure, promoting lithium-ion transport, and improving lithium-ion conductivity. In addition, the copolymerization of fluorinated acrylate monomers in this invention helps to form a lithium fluoride-rich solid electrolyte interface layer, improving interface stability.

Description

Technical Field

[0001] This invention belongs to the field of secondary battery technology, specifically relating to a ternary copolymer fluorinated acrylate gel polymer electrolyte, its preparation method, and its application in quasi-solid-state batteries. Background Technology

[0002] With the continued growth in market demand for high-energy-density and high-safety lithium-ion batteries, the development of a new generation of lithium-ion batteries with high energy density, high safety, and long lifespan is imperative. Currently, traditional lithium-ion batteries pose serious safety hazards under abuse conditions, such as the release of toxic fumes, flammability, and explosions, leading to severe safety accidents. Therefore, designing and developing solid-state polymer electrolytes with high flexibility, high air stability, low flammability, and strong leak-proof properties to replace traditional liquid electrolytes is a crucial strategy for developing next-generation lithium-ion batteries.

[0003] Due to the low lithium-ion conductivity of solvent-free all-solid polymer electrolytes (less than 10 at room temperature) -4 S cm -1 Since batteries are difficult to operate at room temperature, preparing a gel-type polymer electrolyte containing an electrolyte can effectively improve lithium-ion conductivity (greater than 10). -3 S cm -1 However, current gel electrolytes are mainly prepared by polymerizing ethylene carbonate (VEC), vinylene carbonate (VC), and poly(ethylene glycol) methyl ether methacrylate (PEGMA). VC and VEC have a degree of polymerization of only 50-80%, leaving over 20% of monomers containing double bonds. These double-bonded monomers are slowly oxidized at high voltages, which is detrimental to battery life. While PEGMA monomers are nearly 100% polymer, the ether oxygen bonds in its molecular structure are not resistant to high voltages and are oxidized above 4.0V. Therefore, it is necessary to further develop novel polymerizable monomers to meet requirements such as high monomer conversion rate, strong liquid absorption capacity, and high chemical and electrochemical stability.

[0004] Therefore, designing and developing monomers that can be polymerized in situ inside the battery, have strong liquid absorption capacity, and possess high monomer conversion rate, high chemical and electrochemical stability are crucial for the development of polymer electrolytes with high lithium-ion conductivity, compatibility with liquid electrolytes, and high voltage resistance. Summary of the Invention

[0005] Traditional liquid electrolytes pose serious safety risks, while all-solid-state polymer electrolytes suffer from low lithium-ion conductivity at room temperature. This invention provides a ternary copolymer fluorinated acrylate gel polymer electrolyte, its preparation method, and its applications. By designing and controlling the structure of the ternary copolymer fluorinated acrylate polymer electrolyte, this invention achieves a gel polymer electrolyte with high ion conductivity, high voltage resistance, and strong liquid absorption capacity, opening up new avenues for quasi-solid-state batteries.

[0006] One objective of this invention is to provide a ternary copolymer fluorinated acrylate gel polymer electrolyte, comprising: a ternary copolymer fluorinated acrylate, a lithium salt, and an organic solvent, wherein the structural formula of the ternary copolymer fluorinated acrylate is:

[0007]

[0008] In formula (I), a is an integer between 0 and 4, b is an integer between 1 and 7, c is an integer between 1 and 7, d is an integer between 0 and 4, e is an integer between 1 and 7, f is an integer between 0 and 4, x is 1 to 850000, y is 1 to 850000, z is 1 to 150000, R1 is at least one of F and fluoroalkyl groups, and R2 and R3 are each independently selected from at least one of H, F, alkyl groups, and fluoroalkyl groups; preferably, in formula (I), a is 0 to 3 The integers are between 1 and 4, b is an integer between 1 and 4, c is an integer between 1 and 4, d is an integer between 0 and 3, e is an integer between 1 and 4, f is an integer between 0 and 3, x is 10 to 700000, y is 10 to 700000, z is 1 to 100000, R1 is at least one of F and fluorinated alkyl groups having 1 to 3 carbon atoms, and R2 and R3 are each independently selected from at least one of H, F, alkyl groups having 1 to 3 carbon atoms, and fluorinated alkyl groups having 1 to 3 carbon atoms.

[0009] The ternary copolymer fluorinated acrylate gel polymer electrolyte provided by this invention contains:

[0010] The number average molecular weight of the ternary copolymer fluorinated acrylate is 1,000 to 900,000, preferably 1,500 to 850,000, and more preferably 3,500 to 500,000.

[0011] The lithium salt is selected from lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium perchlorate (LiClO4), lithium dioxaborate (LiBOB), lithium tetrafluoroborate (BF4Li), lithium hexafluoroarsenate (LiAsF6), lithium hexafluorophosphate (LiPF6), and lithium bis(trifluoromethanesulfonyl)imide (LiFSI), preferably at least one of lithium hexafluorophosphate (LiPF6) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI);

[0012] The organic solvent is selected from at least one of ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), methyl formate (MF), methyl acetate (MA), methyl butyrate (MB), ethyl propionate (EP), methyl methyl carbonate (EMC), dimethyl carbonate (DMC), and diethyl carbonate (DEC), preferably at least one of fluoroethylene carbonate (FEC), propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and methyl methyl carbonate (EMC).

[0013] Based on a total weight of 100 wt% of the ternary copolymer fluorinated acrylate gel polymer electrolyte, the content of the ternary copolymer fluorinated acrylate is 5-85 wt%, preferably 15-80 wt%; the content of the organic solvent is 10-75 wt%, preferably 15-70 wt%; and the content of the lithium salt is 5-75 wt%, preferably 10-55 wt%.

[0014] A second objective of this invention is to provide a method for preparing the above-mentioned ternary copolymer fluorinated acrylate gel polymer electrolyte, comprising: stirring a precursor solution containing acrylate monomers with alkyl carbonate groups, acrylate monomers with ethylene carbonate groups, fluorinated acrylate monomers, lithium salt, and an organic solvent until homogeneous; and then performing a polymerization reaction under the action of an initiator to obtain the ternary copolymer fluorinated acrylate gel polymer electrolyte; preferably,

[0015] The structural formula of the acrylate monomer containing alkyl carbonate groups is shown in Formula (II):

[0016]

[0017] In formula (II), a is an integer between 0 and 4, b is an integer between 1 and 7, and c is an integer between 1 and 7; preferably, a is an integer between 0 and 3, b is an integer between 1 and 4, and c is an integer between 1 and 4.

[0018] The structural formula of the acrylate monomer containing ethylene carbonate groups is shown in formula (Ⅲ):

[0019]

[0020] In formula (Ⅲ), d is an integer between 0 and 4, and e is an integer between 1 and 7; preferably, d is an integer between 0 and 3, and e is an integer between 1 and 4.

[0021] The structural formula of the fluorinated acrylate monomer is shown in Formula (Ⅳ):

[0022]

[0023] In formula (IV), f is an integer between 0 and 4, R1 is at least one of F and fluoroalkyl, and R2 and R3 are each independently selected from at least one of H, F, alkyl, and fluoroalkyl; preferably, f is an integer between 0 and 3, R1 is at least one of F and fluoroalkyl with 1 to 3 carbon atoms, and R2 and R3 are each independently selected from at least one of H, F, alkyl with 1 to 3 carbon atoms, and fluoroalkyl with 1 to 3 carbon atoms.

[0024] The terpolymerized fluorinated acrylate provided by the present invention is obtained by random copolymerization of three monomers, namely, an acrylate monomer containing an alkyl carbonate group of formula (II), an acrylate monomer containing an ethylene carbonate group of formula (III), and a fluorinated acrylate monomer of formula (IV). There is no particular limitation on the usage ratio of the above three monomers, and any ratio of the above three monomers can be adopted. Preferably, based on the total molar amount of the above three monomers being 100 mol, the molar usage amount (a) of the acrylate monomer containing an alkyl carbonate group is 1 mol < a < 100 mol, preferably 1 mol < a < 90 mol, the molar usage amount (b) of the acrylate monomer containing an ethylene carbonate group is 1 mol < b < 100 mol, preferably 1 mol < b < 90 mol, and the molar usage amount (c) of the fluorinated acrylate monomer is 1 mol < c < 100 mol, preferably 1 mol < c < 50 mol.

[0025] In the preparation method of the terpolymerized fluorinated acrylate gel polymer electrolyte provided by the present invention, the fluorinated acrylate monomer is selected from at least one of ethyl 2-fluoromethylacrylate, trifluoroethyl methacrylate, tetrafluoropropyl methacrylate (TFPMA), pentafluoropropyl methacrylate, 2,2,2-trifluoroethyl acrylate, and 1,1,1,3,3,3-hexafluoroisopropyl acrylate. The structural formulas of the above fluorinated acrylate monomers are as follows:

[0026]

[0027] In the preparation method of the ternary copolymer fluorinated acrylate gel polymer electrolyte provided by the present invention, the initiator is selected from at least one of photoinitiators and thermal initiators, preferably from at least one of 2-hydroxy-2-methyl-1-phenylpropanone, methyl benzoylcarbamate, 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2-methyl-2-(4-morpholino)-1-[4-(methylthio)phenyl]-1-propanone, azobisisobutyronitrile, dimethyl azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide, more preferably from at least one of azobisisobutyronitrile, methyl benzoylcarbamate, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide. Based on the total weight of the ternary copolymer fluorinated acrylate gel polymer electrolyte being 100 wt%, the initiator is 0.15 to 4 wt%, preferably 0.25 to 1.25 wt%.

[0028] In the preparation method of the ternary copolymer fluorinated acrylate gel polymer electrolyte provided by the present invention, the polymerization reaction conditions are as follows: polymerization initiated by ultraviolet light, with an ultraviolet light wavelength range of 100-500 nm and an ultraviolet irradiation polymerization time of 2 minutes to 15 hours; preferably, the ultraviolet lamp wavelength range is 150-400 nm and the polymerization time is 5 minutes to 8 hours; or, polymerization initiated by heat, with a polymerization temperature of 35-85°C and a polymerization time of 4-55 hours; preferably, the polymerization temperature is 40-85°C and the polymerization time is 6-24 hours.

[0029] According to the present invention, the acrylate monomer containing alkyl carbonate groups is prepared by esterification of a hydroxyalkyl acrylate compound and a alkyl chloroformate compound under the action of an alkaline compound. The specific reaction is as follows:

[0030]

[0031] The structural formula of the acrylate-hydroxyalkyl ester compound is shown in formula (V):

[0032]

[0033] In formula (V), a is an integer between 0 and 4, and b is an integer between 1 and 7; preferably, a is an integer between 0 and 3, and b is an integer between 1 and 4.

[0034] The structural formula of the alkyl chloroformate compound is shown in formula (VI):

[0035]

[0036] In equation (VI), c is an integer between 1 and 7, preferably an integer between 1 and 4;

[0037] The molar ratio of the hydroxyalkyl acrylate compound and the alkyl chloroformate compound is 1:(0.85-1.5), preferably 1:(1-1.3);

[0038] The basic compound is selected from at least one of organic basic compounds, preferably from at least one of triethylamine and pyridine;

[0039] The molar ratio of the basic compound to the hydroxyalkyl acrylate compound is (1-3):1, preferably (1-1.5):1;

[0040] The esterification reaction is carried out under the following conditions: at -10 to 5°C for 6 to 16 hours under a protective gas atmosphere; preferably, at -5 to 0°C for 8 to 14 hours under a protective gas atmosphere; the protective gas can be a commonly used protective gas, such as nitrogen.

[0041] The esterification reaction is carried out in a solvent, preferably selected from at least one of toluene, tetrahydrofuran, and dichloromethane.

[0042] According to the present invention, the acrylate monomer containing ethylene carbonate groups is prepared by esterification reaction of hydroxyalkyl dioxapentane ketone compounds and alkyl acryloyl chloride compounds under the action of a basic compound. The specific reaction is as follows:

[0043]

[0044] The structural formula of the hydroxyalkyl dioxapentane ketone compound is shown in formula (VII):

[0045]

[0046] In equation (VII), e is an integer between 1 and 7, preferably an integer between 1 and 4;

[0047] The structural formula of the alkyl acryloyl chloride compound is shown in formula (VIII):

[0048]

[0049] In equation (VIII), d is an integer between 0 and 4, preferably an integer between 0 and 3;

[0050] The molar ratio of the hydroxyalkyl dioxapentanone compound and the alkyl acryloyl chloride compound is 1:(0.85-1.3), preferably 1:(1-1.3);

[0051] The basic compound is selected from at least one of organic basic compounds, preferably from at least one of triethylamine and pyridine;

[0052] The molar ratio of the basic compound to the hydroxyalkyl dioxapentanone compound is (1-3):1, preferably (1-1.5):1;

[0053] The esterification reaction is carried out under the following conditions: under a protective gas atmosphere, at -10 to 5°C for 6 to 16 hours; preferably, under a protective gas atmosphere, at -5 to 0°C for 8 to 14 hours; the protective gas can be a commonly used protective gas, such as nitrogen.

[0054] The esterification reaction is carried out in a solvent, preferably selected from at least one of toluene, tetrahydrofuran, and dichloromethane.

[0055] According to a specific embodiment of the present invention, the preparation method of the acrylate monomer containing alkyl carbonate groups or the acrylate monomer containing ethylene carbonate groups specifically includes: adding an acrylic acid-hydroxyalkyl ester compound or a hydroxyalkyl dioxapentane ketone compound and a basic compound to a solvent, and then adding alkyl chloroformate or alkyl acryloyl chloride dropwise under a protective gas to carry out an esterification reaction. After the dropwise addition is completed, the crude esterification product is obtained, and the crude product is purified to obtain the acrylate monomer containing alkyl carbonate groups or the acrylate monomer containing ethylene carbonate groups. The solvent can be at least one of anhydrous toluene, tetrahydrofuran, and dichloromethane; the protective gas can be at least one of nitrogen or argon; the purification treatment can be carried out by extraction, silica gel column chromatography, and solvent elution. The extractant used in the extraction method is at least one of ethyl acetate, dichloromethane, trichloromethane, and toluene; the eluent used in the solvent elution is a mixed solvent of ethyl acetate and n-hexane.

[0056] The third objective of this invention is to provide a quasi-solid-state battery, comprising a negative electrode, a positive electrode, a separator, and a ternary copolymer fluorinated acrylate gel polymer electrolyte, wherein the ternary copolymer fluorinated acrylate gel polymer electrolyte is the ternary copolymer fluorinated acrylate gel polymer electrolyte described in the first objective of this invention or the ternary copolymer fluorinated acrylate gel polymer electrolyte obtained by the preparation method described in the second objective of this invention.

[0057] In the quasi-solid-state battery provided by this invention:

[0058] The negative electrode is at least one of graphite, lithium titanate, lithium metal, graphite / silicon composite, silicon-based alloy, and tin-based alloy;

[0059] The diaphragm is selected from at least one of polyethylene, polyvinylidene fluoride, polypropylene, polypropylene / polyethylene double-layer composite diaphragm, and polypropylene / polyethylene / polypropylene triple-layer composite diaphragm;

[0060] The positive electrode comprises a positive electrode active material, conductive carbon black, a binder, and a current collector; more preferably, the positive electrode active material is selected from lithium nickel cobalt aluminum oxide (LiNi). x Co y Al z O2, (x+y+z=1)), lithium iron manganese phosphate (LiFe) x Mn y PO4 (x+y=1)), lithium iron phosphate (LiFePO4), lithium manganese oxide (LiMn2O4), lithium nickel cobalt manganese oxide (LiNi x Co y Mn z At least one of O2 (x+y+z=1) and lithium cobalt oxide (LiCoO2); the binder is selected from at least one of polyvinylidene fluoride, polydifluoroethylene, polytetrafluoroethylene, polyvinyl alcohol, and polyurethane; the current collector is selected from at least one of aluminum foil and copper foil; based on a total weight of 100wt% for the positive electrode active material, conductive carbon black, and binder, the positive electrode active material is 50-95wt%, the conductive carbon black is 1-25wt%, and the binder is 4-25wt%.

[0061] The fourth objective of this invention is to provide a method for preparing the above-mentioned quasi-solid-state battery, comprising:

[0062] A precursor solution is prepared by uniformly mixing components including acrylate monomers containing alkyl carbonate groups, acrylate monomers containing ethylene carbonate groups, fluorinated acrylate monomers, lithium salts, initiators, and organic solvents. This precursor solution is then injected into a battery assembled from a positive electrode, a negative electrode, and a separator. Polymerization is initiated inside the battery by heating, resulting in a quasi-solid-state battery. Alternatively,

[0063] A precursor solution is prepared by uniformly stirring components including acrylate monomers containing alkyl carbonate groups, acrylate monomers containing ethylene carbonate groups, fluorinated acrylate monomers, lithium salts, initiators, and organic solvents. This precursor solution is then coated onto a separator, and polymerization is initiated on the separator by heating or ultraviolet light to obtain a quasi-solid-state electrolyte membrane. This membrane is then assembled with positive and negative electrodes to form a quasi-solid-state battery. Alternatively...

[0064] A precursor solution is obtained by stirring a mixture of components including acrylate monomers containing alkyl carbonate groups, acrylate monomers containing ethylene carbonate groups, fluorinated acrylate monomers, lithium salts, initiators, and organic solvents. The precursor solution is then coated onto a positive electrode and / or a negative electrode, and polymerization is carried out on the positive electrode and / or a negative electrode by heating or ultraviolet light initiation to obtain a quasi-solid-state electrolyte composite positive electrode and / or a negative electrode. A quasi-solid-state battery is obtained by selecting the opposite electrodes of the positive electrode and / or a negative electrode and assembling the quasi-solid-state electrolyte membrane.

[0065] This invention employs three acrylate monomers with high monomer conversion rates and no ether groups for copolymerization, achieving a monomer conversion rate greater than 99%. This avoids the impact of residual monomers on the electrochemical performance of the battery and improves the oxidation resistance of the gel polymer electrolyte system. Furthermore, the acrylate monomers containing ethylene carbonate groups and alkyl carbonate groups used in this invention have structures similar to most solvent molecules. Utilizing the non-covalent interactions between these groups and solvent molecules, solvent molecules can be better immobilized within the polymer network, forming a uniform network structure that promotes lithium-ion transport and improves lithium-ion conductivity. In addition, this invention copolymerizes fluorinated acrylate monomers, which helps form a lithium fluoride-rich solid electrolyte interface layer, improving interface stability. Compared with existing technologies, this invention has the following advantages:

[0066] (1) The present invention uses three acrylate monomers with high monomer conversion rate and no ether group for copolymerization. The monomer conversion rate is greater than 99%, which avoids the influence of residual monomer on the electrochemical performance of the battery and improves the antioxidant properties of the gel polymer electrolyte system.

[0067] (2) In this invention, the ethylene carbonate and alkyl carbonate groups in the acrylate monomers containing ethylene carbonate groups and acrylate monomers containing alkyl carbonate groups have structures similar to most solvent molecules. Utilizing the non-covalent interactions between these groups and solvent molecules, solvent molecules can be better immobilized in the polymer network, forming a uniform network structure, promoting lithium-ion transport, and improving lithium-ion conductivity. Furthermore, this invention copolymerizes fluorinated acrylate monomers, which helps form a lithium fluoride-rich solid electrolyte interface layer, improving interface stability. Attached Figure Description

[0068] Figure 1 The graph shows a comparison of the ionic conductivity of the gel polymer electrolytes obtained in Examples 1-5 in the presence of different solvents. Figure 1 In the figure, the horizontal axis represents temperature (1000 / TK). -1 The vertical axis represents the logarithm of ionic conductance (S cm⁻¹). -1 ).

[0069] Figure 2a ~b are the cyclic voltammograms of lithium / / iron (Li / P(DOA-PCPA-TFPMA)with EC&DEC&FEC / Fe) batteries assembled under different lithium salt conditions obtained in Examples 5 and 6, respectively. Figure 2a In ~b, the horizontal axis represents voltage (V) and the vertical axis represents current (mA).

[0070] Figure 3a ~b are impedance diagrams corresponding to the cyclic voltammetry tests of lithium / / iron (Li / P(DOA-PCPA-TFPMA)with EC&DEC&FEC / Fe) batteries assembled under different lithium salt conditions obtained in Examples 5 and 6, respectively. Figure 3a In ~b, the horizontal axis represents the real part of the impedance (Ωcm). 2 The vertical axis represents the imaginary part of the impedance (Ωcm). 2 ).

[0071] Figure 4a ~b are comparison graphs of electrochemical float tests of P(DOA-PCPA-TFPMA) with EC&DEC&FEC obtained in Example 5 and P(VEC-TFPMA) with EC&DEC&FEC obtained in Comparative Example 1. Figure 4a In ~b, the horizontal axis represents time (h) and the vertical axis represents current (mA).

[0072] Figure 5a Figures 1-2b show the charge-discharge voltage curves of lithium / / lithium symmetric batteries (Li / / Li, Li / P(DOA-PCPA-TFPMA)with EC&DEC&FEC / Li) assembled in Examples 5-6 with different lithium salts, respectively, under long-term cycling conditions, with a current density of 0.5 mA·cm⁻¹. -2 Each charge and discharge cycle lasts 1 hour. Figure 5a In ~b, the horizontal axis represents time (h) and the vertical axis represents voltage (V).

[0073] Figure 6aFigures 1-2b represent the impedances corresponding to the charge-discharge curves of lithium / / lithium symmetric batteries (Li / / Li, Li / P(DOA-PCPA-TFPMA)with EC&DEC&FEC / Li) assembled under different lithium salts obtained in Examples 5-6, respectively, during long-term cycling, with a current density of 0.5 mA·cm⁻¹. -2 Each charge and discharge cycle lasts 1 hour. Figure 6a In ~b, the horizontal axis represents the real part of the impedance (Ωcm). 2 The vertical axis represents the imaginary part of the impedance (Ωcm). 2 ).

[0074] Figures 7-8 The charge-discharge curves and cycle performance diagrams of the Li / P (DOA-PCPA-TFPMA) with EC&DEC&FEC / NCM85 quasi-solid-state battery C1 in Example 7 are shown at 25°C. Figure 7 In the figure, the horizontal axis represents specific capacity (mAh g). -1 The vertical axis represents voltage (V); Figure 8 In the diagram, the horizontal axis represents the number of cycles, and the vertical axis on the left represents the specific capacity (mAh g). -1 The right-hand vertical axis represents the Coulomb efficiency (%).

[0075] Figure 9 The graph shows the charge-discharge curve of the Li / P (DOA-PCPA-TFPMA) quasi-solid-state battery C2 with EC&DEC&FEC / LCO in Example 8 at 25°C. The horizontal axis represents the specific capacity (mAh g). -1 The vertical axis represents voltage (V).

[0076] Figure 10 The graph shows the cycle performance of the Li / P (VEC-TFPMA) quasi-solid-state battery C3 with EC&DEC&FEC / LCO in Comparative Example 2 at 25℃. The horizontal axis represents the specific capacity (mAh g). -1 The vertical axis represents voltage (V).

[0077] Figure 11 This graph shows the cycle performance of the Li / P (DOA-PCPA-TFPMA) quasi-solid-state battery C2 with EC&DEC&FEC / LCO in Example 8 and the Li / P (VEC-TFPMA) quasi-solid-state battery C3 with EC&DEC&FEC / LCO in Comparative Example 2 at 25°C. The horizontal axis represents the number of cycles, and the left vertical axis represents the specific capacity (mAh g). -1 The right-hand vertical axis represents the Coulomb efficiency (%). Detailed Implementation

[0078] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0079] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0080] Preparation Example 1

[0081] Preparation of ethyl propylene carbonate (PCPA):

[0082] In a three-necked flask, 30 g of 2-hydroxyethyl acrylate and 28 g of pyridine were added to 200 mL of anhydrous dichloromethane. Under nitrogen protection and at 0 °C, 42 g of propyl chloroformate was added dropwise to carry out the esterification reaction. After the addition was completed, the reaction was continued for 8 hours. After the esterification reaction was completed, crude ethyl propyl carbonate was obtained. The crude product was extracted with dichloromethane and then subjected to silica gel column chromatography with eluent (ethyl acetate: n-hexane = 1:10) to obtain light yellow oily ethyl propyl carbonate (PCPA).

[0083]

[0084] Preparation Example 2

[0085] Preparation of ethylene acrylate (DOA):

[0086] In a three-necked flask, 30 g of hydroxymethyldioxacyclophenone and 27 g of pyridine were added to 200 mL of anhydrous dichloromethane. Under nitrogen protection and at 0 °C, 28 g of acryloyl chloride was added dropwise to carry out the esterification reaction. After the addition was completed, the reaction was continued for 8 hours. After the esterification reaction was completed, crude acrylate (ethylene carbonate) was obtained. The crude product was extracted with dichloromethane and then subjected to silica gel column chromatography with eluent (ethyl acetate: n-hexane = 1:4) to obtain light yellow oily acrylate (DOA).

[0087]

[0088] Example 1

[0089] (1) Preparation of DEC-containing poly(vinyl carbonate-ethylene propylene carbonate-fluorinated acrylate) gel polymer electrolyte:

[0090]

[0091] 0.24 g of PCPA, 0.23 g of DOA, 0.03 g of 2,2,3,3-tetrafluoropropyl methacrylate (TFPMA), 0.32 g of LiPF6, 1.2 g of DEC, and 0.011 g of azobisisobutyronitrile (AIBN) were added to a screw-top bottle and stirred evenly at room temperature to obtain precursor solution A. After initiation at 60 °C for 1 hour, precursor solution A was polymerized at 45 °C for 11 hours to obtain poly(vinyl carbonate-ethylene propylene carbonate-fluorinated acrylate) gel polymer electrolyte P(DOA-PCPA-TFPMA) with DEC. The number average molecular weight of P(DOA-PCPA-TFPMA) was 150,000.

[0092] (2) Battery assembly:

[0093] The precursor solution A obtained in step (1) was coated onto a porous polypropylene membrane. After the porous polypropylene membrane was completely impregnated with the precursor solution A, a battery was assembled using stainless steel sheet (Fe) as the positive and negative electrodes. The battery was subjected to initiation at 60°C for 1 hour and polymerization at 45°C for 11 hours to obtain a symmetrical Fe / P (DOA-PCPA-TFPMA) with DEC / Fe. This battery was used to test the lithium-ion conductivity of the gel polymer electrolyte. Figure 1 As shown.

[0094] Example 2

[0095] (1) Preparation of poly(vinyl carbonate-ethylene propylene carbonate-fluorinated acrylate) gel polymer electrolyte containing DMC:

[0096] 0.24 g of PCPA, 0.23 g of DOA, 0.03 g of TFPMA, 0.30 g of LiPF6, 1.2 g of DMC, and 0.011 g of AIBN were added to a screw-top bottle and stirred evenly at room temperature to obtain precursor solution B. After initiation at 60 °C for 1 hour, precursor solution B was polymerized at 45 °C for 11 hours to obtain poly(ethylene carbonate-ethylene propylene carbonate-acrylate) gel polymer electrolyte P(DOA-PCPA-TFPMA) with DMC. The number average molecular weight of P(DOA-PCPA-TFPMA) was 145,000.

[0097] (2) Battery assembly:

[0098] The precursor solution B obtained in step (1) was coated onto a porous polypropylene membrane. After the porous polypropylene membrane was completely impregnated with the precursor solution B, a battery was assembled using Fe sheets as the positive and negative electrodes. The battery was subjected to initiation at 60°C for 1 hour and polymerization at 45°C for 11 hours to obtain a symmetrical Fe / P (DOA-PCPA-TFPMA) with DMC / Fe battery. This battery was used to test the lithium-ion conductivity of the gel polymer electrolyte. Figure 1 As shown.

[0099] Example 3

[0100] (1) Preparation of poly(ethylene carbonate-ethylene propylene carbonate-fluorinated acrylate) gel polymer electrolyte containing EC:

[0101] 0.24 g of PCPA, 0.23 g of DOA, 0.03 g of TFPMA, 0.27 g of LiPF6, 1.23 g of EC, and 0.011 g of AIBN were added to a screw-top bottle and stirred evenly at room temperature to obtain precursor solution C. After initiation at 60 °C for 1 hour, the precursor solution C was polymerized at 45 °C for 11 hours to obtain poly(ethylene carbonate-ethylene propylene carbonate-fluorinated acrylate) gel polymer electrolyte P(DOA-PCPA-TFPMA) with EC. The number average molecular weight of P(DOA-PCPA-TFPMA) was 160,000.

[0102] (2) Battery assembly:

[0103] The precursor solution C obtained in step (1) was coated onto a porous polypropylene membrane. After the porous polypropylene membrane was completely impregnated with the precursor solution C, a battery was assembled using Fe sheets as the positive and negative electrodes. The battery was subjected to initiation at 60°C for 1 hour and polymerization at 45°C for 11 hours to obtain a symmetrical Fe / P (DOA-PCPA-TFPMA) with EC / Fe structure. This structure was used to test the lithium-ion conductivity of the gel polymer electrolyte. Figure 1 As shown.

[0104] Example 4

[0105] (1) Preparation of poly(vinyl carbonate-ethylene propylene carbonate-fluorinated acrylate) gel polymer electrolyte containing PC:

[0106] 0.24 g of PCPA, 0.23 g of DOA, 0.03 g of TFPMA, 0.28 g of LiPF6, 1.22 g of PC, and 0.011 g of AIBN were added to a screw-top bottle and stirred evenly at room temperature to obtain precursor solution D. After initiation at 60 °C for 1 hour, the precursor solution D was polymerized at 45 °C for 11 hours to obtain poly(vinyl carbonate-ethylene propylene carbonate-fluorinated acrylate) gel polymer electrolyte P(DOA-PCPA-TFPMA) with PC. The number average molecular weight of P(DOA-PCPA-TFPMA) was 160,000.

[0107] (2) Battery assembly:

[0108] The precursor solution D obtained in step (1) was coated onto a porous polypropylene membrane. After the porous polypropylene membrane was completely impregnated with the precursor solution D, a battery was assembled using Fe sheets as the positive and negative electrodes. The battery was subjected to initiation at 60°C for 1 hour and polymerization at 45°C for 11 hours to obtain a symmetrical Fe / P (DOA-PCPA-TFPMA) with PC / Fe battery. This battery was used to test the lithium-ion conductivity of the gel polymer electrolyte. Figure 1 As shown.

[0109] Example 5

[0110] (1) Preparation of poly(vinyl carbonate-ethylene propylene carbonate-fluorinated acrylate) gel polymer electrolyte containing EC, DEC and FEC:

[0111] 0.47 g of PCPA, 0.47 g of DOA, 0.058 g of TFPMA, 0.56 g of LiPF6, 1.22 g of EC, 0.61 g of DEC, 0.61 g of FEC, and 0.017 g of AIBN were added to a screw-top bottle and stirred evenly at room temperature to obtain precursor solution E. After initiation at 60 °C for 1 hour, precursor solution E was polymerized at 45 °C for 11 hours to obtain poly(ethylene carbonate-ethylene propylene carbonate-fluorinated acrylate) gel polymer electrolyte P(DOA-PCPA-TFPMA) with EC, DEC, and FEC. The number average molecular weight of P(DOA-PCPA-TFPMA) was 180,000.

[0112] (2) Battery assembly:

[0113] (2-1) The precursor solution E obtained in step (1) above is coated onto a porous polypropylene membrane. After the porous polypropylene membrane is completely impregnated with the precursor solution E, a battery is assembled using Fe sheets as the positive and negative electrodes. The battery is placed at 60°C for 1 hour for initiation and then at 45°C for 11 hours for polymerization to obtain a symmetrical Fe / P(DOA-PCPA-TFPMA) with EC&DEC&FEC / Fe battery. This battery is used to test the lithium-ion conductivity of the gel polymer electrolyte. Figure 1 As shown.

[0114] (2-2) The precursor solution E obtained in step (1) above is coated onto a porous polypropylene membrane. After the porous polypropylene membrane is completely impregnated with the precursor solution E, a battery is assembled using Fe as the positive electrode and lithium (Li) as the negative electrode. The battery is subjected to initiation at 60°C for 1 hour and polymerization at 45°C for 11 hours to obtain a Li / P (DOA-PCPA-TFPMA) battery with EC&DEC&FEC / Fe. The cyclic voltammogram of this gel polymer electrolyte is then tested, as shown in the figure. Figure 2a and Figure 3a As shown.

[0115] (2-3) The precursor solution E obtained in step (1) above is coated onto a porous polypropylene membrane. After the porous polypropylene membrane is completely impregnated with the precursor solution E, a battery is assembled using Li sheets as the positive and negative electrodes. The battery is placed at 60°C for 1 hour for initiation and then at 45°C for 11 hours for polymerization to obtain a symmetrical Li / P (DOA-PCPA-TFPMA) with EC&DEC&FEC / Li. This is used to test the long-term stability of the gel polymer electrolyte with lithium metal, such as... Figure 5a and Figure 6a As shown.

[0116] (2-4) Inject the polymerization precursor solution E obtained in step (1) above into lithium nickel cobalt manganese oxide (LiNi) 0.85 Co 0.1 Mn 0.05 In a battery assembled with O2 (NCM85) as the positive electrode, Li sheets as the negative electrode, and a porous polypropylene separator, after standing for 24 hours to allow the precursor solution to fully diffuse, it was initiated at 60°C for 1 hour and then polymerized at 45°C for 11 hours to obtain a Li / P (DOA-PCPA-TFPMA) battery with EC&DEC&FEC / NCM85. The compatibility of this system with the high-voltage positive electrode was tested, such as... Figure 4a As shown.

[0117] (2-5) The polymerization precursor solution E obtained in step (1) above is injected into a battery assembled with lithium cobalt oxide (LiCoO2, LCO) as the positive electrode, Li sheet as the negative electrode and porous polypropylene membrane. After standing for 24 hours to allow the precursor solution to fully diffuse, it is initiated at 60°C for 1 hour and then polymerized at 45°C for 11 hours to obtain Li / P (DOA-PCPA-TFPMA) with EC&DEC&FEC / LCO battery.

[0118] Example 6

[0119] (1) Preparation of poly(vinyl carbonate-ethylene propylene carbonate-fluorinated acrylate) gel polymer electrolyte containing EC, DEC and FEC:

[0120] 0.47 g of PCPA, 0.47 g of DOA, 0.058 g of TFPMA, 0.78 g of LiTFSI, 1.15 g of EC, 0.54 g of DEC, 0.54 g of FEC, and 0.016 g of AIBN were added to a screw-top bottle and stirred evenly at room temperature to obtain precursor solution F. After initiation at 60 °C for 1 hour, the precursor solution F was polymerized at 45 °C for 11 hours to obtain poly(ethylene carbonate-ethylene propylene carbonate-fluorinated acrylate) gel polymer electrolyte P(DOA-PCPA-TFPMA) with EC, DEC, and FEC. The number average molecular weight of P(DOA-PCPA-TFPMA) was 188,000.

[0121] (2) Battery assembly:

[0122] (2-1) The precursor solution F obtained in step (1) above is coated onto a porous polypropylene membrane. After the porous polypropylene membrane is completely impregnated with the precursor solution F, a battery is assembled using Fe sheets as the positive and negative electrodes. The battery is placed at 60°C for 1 hour for initiation and then at 45°C for 11 hours for polymerization to obtain a symmetrical Fe / P(DOA-PCPA-TFPMA) with EC&DEC&FEC / Fe battery. This battery is used to test the lithium-ion conductivity of the gel polymer electrolyte. Figure 1 As shown.

[0123] (2-2) The precursor solution F obtained in step (1) above is coated onto a porous polypropylene membrane. After the porous polypropylene membrane is completely impregnated with the precursor solution F, a battery is assembled using Fe as the positive electrode and lithium (Li) as the negative electrode. The battery is subjected to initiation at 60°C for 1 hour and polymerization at 45°C for 11 hours to obtain a Li / P (DOA-PCPA-TFPMA) battery with EC&DEC&FEC / Fe. This battery is used to test the cyclic voltammetric properties of the gel polymer electrolyte, such as... Figure 2b and Figure 3b As shown.

[0124] (2-3) The precursor solution F obtained in step (1) above is coated onto a porous polypropylene membrane. After the porous polypropylene membrane is completely impregnated with the precursor solution F, a battery is assembled using Li sheets as the positive and negative electrodes. The battery is placed at 60°C for 1 hour for initiation and then at 45°C for 11 hours for polymerization to obtain a symmetrical Li / P (DOA-PCPA-TFPMA) with EC&DEC&FEC / Li battery. This battery is used to test the long-term stability of the gel polymer electrolyte system with lithium metal. Figure 5b and Figure 6b As shown.

[0125] Comparative Example 1

[0126] (1) Preparation of poly(vinyl carbonate-fluorinated acrylate) gel polymer electrolytes containing EC, DEC and FEC:

[0127]

[0128] 1.73 g of ethylene carbonate (VEC), 0.16 g of TFPMA, 0.40 g of LiPF6, 2.44 g of EC, 1.22 g of DEC, 1.22 g of FEC, and 0.033 g of AIBN were added to a screw-top bottle and stirred evenly at room temperature to obtain precursor solution I. After polymerization of precursor solution I at 65 °C for 30 hours, a fluorinated poly(ethylene carbonate-fluorinated acrylate) gel polymer electrolyte P(VEC-TFPMA) containing EC, DEC, and FEC was obtained. The number average molecular weight of P(VEC-TFEMA) was 55,000.

[0129] (2) Battery assembly

[0130] The polymerization precursor solution I obtained in step (1) above was injected into a battery assembled with NCM85 as the positive electrode, Li sheet as the negative electrode, and a porous polypropylene membrane. After standing for 24 hours to allow the precursor solution to fully diffuse, polymerization was carried out at 65°C for 30 hours to obtain a Li / P (VEC-TFPMA) battery with EC&DEC&FEC / NCM85. The matching of this system with the high-voltage positive electrode was tested, such as... Figure 4b As shown.

[0131] Test Example 1: Lithium-ion conductivity test of P (DOA-PCPA-TFPMA) polymer electrolyte in different solvent systems

[0132] The impedance of Fe / / Fe symmetric cells assembled with gel polymer electrolytes in Examples 1-5 was measured using an electrochemical workstation (SolartronAnalytical 1470E). The lithium-ion conductivity of the P(DOA-PCPA-TFPMA) polymer electrolyte in different solvent systems was also calculated. The test temperature range was 25-70℃.

[0133] like Figure 1 As shown, the experimental results indicate that the lithium-ion conductivity of the LiPF6-containing P(DOA-PCPA-TFPMA) polymer electrolyte in different solvent systems exhibits the following trend: EC > DMC > PC > DEC. The LiPF6-containing P(DOA-PCPA-TFPMA) polymer electrolyte shows relatively high lithium-ion conductivity (>10) in both EC and DMC solutions. -3 Scm -1 This may be because EC and DOA in the copolymer have similar cyclic carbonate structures, and DMC and PCPA in the copolymer also have similar linear carbonate structures. Therefore, this ternary copolymer has strong van der Waals forces with both EC and DMC, which can lock EC and DMC in the polymer network structure, forming a uniform and rapid lithium-ion transport channel and improving lithium-ion conductivity. Furthermore, for DEC, due to the relatively large size of DEC molecules, it is difficult for them to enter the polymer chain segments, and the solvation effect of DEC with lithium ions is relatively weak. Therefore, the lithium-ion conductivity of the P(DOA-PCPA-TFPMA) polymer electrolyte is relatively low (<10) in the presence of DEC. -3 S cm -1 (but still greater than 10) -4 S cm -1 Therefore, the ethylene carbonate and alkyl carbonate groups contained in the ternary copolymer fluorinated acrylate polymer electrolyte provided by this invention help to lock solvent molecules in the polymer electrolyte network structure, thereby forming a uniform and rapid lithium-ion transport channel and improving lithium-ion conductivity.

[0134] Test Example 2: Electrochemical Performance Testing of Gel Polymer Electrolytes

[0135] Cyclic voltammetry (CV) tests were performed on the Li / / Fe batteries assembled in Examples 5 and 6 using a Solartron Analytical 1470E electrochemical workstation to test the stability of the gel polymer system to lithium metal and its electrochemical stability window in the presence of different lithium salts. The test temperature was set to 25°C and the CV scan rate was set to 0.2 mV / s. -1The scan range was set from OCV (open circuit voltage) to -0.5V and then to 1V. The Li / / Li symmetric cells assembled in Examples 5 and 6 were tested using a LAND series battery testing system. The test temperature was set to 25°C, and the test current density was 0.5 mA / cm². 2 The charge and discharge times were each 1 hour. Electrochemical float tests were performed on the Li / / NCM85 assembled in Example 5 and Comparative Example 1 using a LAND series battery testing system. The test temperature was set to 25°C, and the test voltage range was 4.1-5V.

[0136] To test the interfacial stability of P(DOA-PCPA-TFPMA) with the lithium metal anode in the presence of different lithium salts (LiTFSi and LiPF6), CV tests were performed on Li / P(DOA-PCPA-TFPMA) batteries with EC&DEC&FEC / Fe, as shown in Figures 2 and 3. The experimental results show that when the gel polymer electrolyte system contains LiPF6, the current gradually increases in the first two cycles. After a stable interfacial passivation layer is formed, the CV curves in cycles 3 to 5 overlap well with no significant increase in impedance. When the gel polymer electrolyte system contains LiTFSi, after the formation of the interfacial passivation layer in the first cycle, the CV curves in cycles 2 to 5 overlap well with no significant increase in impedance. These results indicate that the gel polymer electrolyte exhibits good interfacial stability with the lithium metal anode in the presence of either LiPF6 or LiTFSi.

[0137] Electrochemical float tests were performed on the Li / P (DOA-PCPA-TFPMA) with EC&DEC&FEC / NCM85 batteries in Example 5 and the Li / P (VEC-TFPMA) with EC&DEC&FEC / NCM85 batteries in Comparative Example 1 in the presence of LiPF6. Figure 4aAs shown in ~b. Experiments show that for Li / P(DOA-PCPA-TFPMA) with EC&DEC&FEC / NCM85, the leakage current remained stable and below 10μA within the test range of 4.1V to 5V. However, for Li / P(VEC-TFPMA) with EC&DEC&FEC / NCM85, the leakage current increased significantly and exceeded 20μA after the voltage exceeded 4.6V. The above results indicate that for VEC, its monomer conversion rate is low, and the residual double bonds are easily oxidized under high voltage, leading to an increase in leakage current. Conversely, for the ternary copolymer fluorinated acrylate provided by this invention, its monomer conversion rate is high, there are no residual double bonds, and its leakage current is still below 10μA at a high voltage of 5V. Therefore, compared with VEC, the ternary copolymer fluorinated acrylate provided by this invention is more suitable for matching high-voltage cathodes.

[0138] To further verify the long-term cycling stability of the ternary copolymer fluorinated acrylate and lithium metal anode of this invention, the interfacial stability with lithium metal was tested for Li / P(DOA-PCPA-TFPMA) with EC&DEC&FEC / Li batteries using different lithium salts, LiTFSI and LiPF6, as shown in Figures 5 and 6. The experiments show that, regardless of whether LiTFSI or LiPF6 is used, the Li / / Li symmetric battery of this gel polymer electrolyte can cycle stably for over 1500 hours without a significant increase in impedance, indicating that the P(DOA-PCPA-TFPMA) gel polymer electrolyte and lithium metal anode possess long-term cycling stability.

[0139] Example 7: Preparation and performance testing of a quasi-solid-state lithium metal battery C1 (Li / P(DOA-PCPA-TFPMA) with EC&DEC&FEC / NCM85 battery):

[0140] Following steps (2-4) of Example 5, a Li / P(DOA-PCPA-TFPMA) quasi-solid-state lithium metal battery C1 with EC&DEC&FEC / NCM85 was prepared. The difference was that this battery used a Li sheet as the negative electrode, NCM85 as the positive electrode active material, polyvinylidene fluoride as the binder, conductive carbon black, aluminum foil as the current collector, and P(DOA-PCPA-TFPMA) containing EC, DEC and FEC as the gel polymer electrolyte. The ratio of active material: binder: conductive carbon black was 85:5:10.

[0141] The performance of Li / P (DOA-PCPA-TFPMA) with EC&DEC&FEC / NCM85 quasi-solid-state battery C1 is as follows:

[0142] The performance of Li / P (DOA-PCPA-TFPMA) with EC&DEC&FEC / NCM85 quasi-solid-state battery C1 was tested using the LAND series battery testing system. The test temperature was 25℃, and the Li / P (DOA-PCPA-TFPMA) with EC&DEC&FEC / NCM85 was tested at a rate of 0.3C.

[0143] like Figures 7-8 As shown, the battery was cycled at a rate of 0.3C, and the highest discharge capacity of the battery was 198.4 mAh g. -1 After 150 cycles, the discharge capacity was 169.2 mAh g. -1 The capacity retention rate was 85.28% (relative to the maximum discharge capacity of 198.4 mAh g). -1 ).

[0144] Example 8: Preparation and performance testing of a quasi-solid-state lithium metal battery C2 (Li / P(DOA-PCPA-TFPMA) with EC&DEC&FEC / LCO battery):

[0145] Following steps (2-5) of Example 5, a Li / P(DOA-PCPA-TFPMA) quasi-solid-state lithium metal battery C2 with EC&DEC&FEC / LCO was prepared. The difference is that this battery uses Li sheet as the negative electrode, LCO as the positive electrode active material, polyvinylidene fluoride as the binder, conductive carbon black, aluminum foil as the current collector, and P(DOA-PCPA-TFPMA) gel polymer electrolyte containing EC, DEC and FEC, wherein the ratio of active material: binder: conductive carbon black is 85:5:10.

[0146] The performance of Li / P (DOA-PCPA-TFPMA) with EC&DEC&FEC / LCO quasi-solid-state battery C2 is as follows:

[0147] This invention uses the LAND series battery testing system to test the battery performance of Li / P (DOA-PCPA-PCPOE) with EC&DEC&FEC / LCO quasi-solid-state battery C2. The test temperature is 25℃, and the Li / P (DOA-PCPA-PCPOE) with EC&DEC&FEC / LCO is tested at a rate of 0.3C.

[0148] like Figure 9 As shown, the battery was cycled at a rate of 0.3C, and the highest discharge capacity of the battery was 191.5 mAh g. -1 After 100 cycles, the discharge capacity is 166.4 mAh g. -1The capacity retention rate was 86.89% (relative to the maximum discharge capacity of 191.5 mAh g). -1 ).

[0149] Comparative Example 2: Preparation and performance testing of quasi-solid-state lithium metal battery C3 (Li / P(VEC-TFPMA) with EC&DEC&FEC / LCO battery):

[0150] Following step (2) of Comparative Example 1, a Li / P(VEC-TFPMA) with EC&DEC&FEC / LCO quasi-solid-state lithium metal battery C3 was prepared. The difference was that this battery used Li sheet as the negative electrode, LCO as the positive electrode active material, polyvinylidene fluoride as the binder, conductive carbon black, aluminum foil as the current collector, and P(VEC-TFPMA) gel polymer electrolyte containing EC, DEC and FEC, wherein the ratio of active material: binder: conductive carbon black = 85:5:10.

[0151] The performance of Li / P (VEC-TFPMA) with EC&DEC&FEC / LCO quasi-solid-state battery C3 is as follows:

[0152] This invention uses the LAND series battery testing system to test the battery performance of Li / P (VEC-TFPMA) with EC&DEC&FEC / LCO quasi-solid-state battery C3. The test temperature is 25℃, and the Li / P (VEC-TFPMA) with EC&DEC&FEC / LCO is tested at a rate of 0.3C.

[0153] like Figure 10 As shown, the battery was cycled at a rate of 0.3C, and the highest discharge capacity of the battery was 201.6 mAh g. -1 After 100 cycles, the discharge capacity was 107.4 mAh g. -1 The capacity retention rate was 53.27% (relative to the maximum discharge capacity of 201.6 mAh g). -1 ).

[0154] from Figure 9-11 The test results show that the presence of residual VEC monomers in the P(VEC-TFPMA) gel polymer electrolyte makes it difficult to match with a high-voltage cathode. In contrast, the ternary copolymer fluorinated acrylate gel polymer electrolyte provided by this invention has almost no residual double-bonded monomers, making it more suitable for matching with a high-voltage cathode.

Claims

1. A ternary copolymer fluorinated acrylate gel polymer electrolyte, comprising: The ternary copolymer fluorinated acrylate, lithium salt, and organic solvent are present, and the structural formula of the ternary copolymer fluorinated acrylate is as follows: Equation (I) In formula (I), a is an integer between 0 and 4, b is an integer between 1 and 7, c is an integer between 1 and 7, d is an integer between 0 and 4, e is an integer between 1 and 7, f is an integer between 0 and 4, x is 1 to 850000, y is 1 to 850000, z is 1 to 150000, R1 is at least one of F and fluoroalkyl, and R2 and R3 are each independently selected from at least one of H, F, alkyl, and fluoroalkyl. The ternary copolymer fluorinated acrylate is obtained by random copolymerization of three monomers: acrylate monomers containing alkyl carbonate groups, acrylate monomers containing ethylene carbonate groups, and fluorinated acrylate monomers. Based on a total weight of 100wt% of the ternary copolymer fluorinated acrylate gel polymer electrolyte, the content of the ternary copolymer fluorinated acrylate is 5-85wt%, the content of the organic solvent is 10-75wt%, and the content of the lithium salt is 5-75wt%.

2. The ternary copolymer fluorinated acrylate gel polymer electrolyte according to claim 1, characterized in that, In formula (I), a is an integer between 0 and 3, b is an integer between 1 and 4, c is an integer between 1 and 4, d is an integer between 0 and 3, e is an integer between 1 and 4, f is an integer between 0 and 3, x is 10 to 700,000, y is 10 to 700,000, z is 1 to 100,000, R1 is at least one of F and a fluorinated alkyl group having 1 to 3 carbon atoms, and R2 and R3 are each independently selected from at least one of H, F, an alkyl group having 1 to 3 carbon atoms, and a fluorinated alkyl group having 1 to 3 carbon atoms; and / or, The ternary copolymer fluorinated acrylate has a number average molecular weight of 1000~900000; and / or, The lithium salt is selected from at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium perchlorate, lithium dioxaborate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium hexafluorophosphate, and lithium bis(trifluoromethanesulfonyl)imide; and / or, The organic solvent is selected from at least one of ethylene carbonate, fluoroethylene carbonate, propylene carbonate, methyl formate, methyl acetate, methyl butyrate, ethyl propionate, methyl methyl carbonate, dimethyl carbonate, and diethyl carbonate; and / or, Based on a total weight of 100wt% of the ternary copolymer fluorinated acrylate gel polymer electrolyte, the content of the ternary copolymer fluorinated acrylate is 15-80wt%; the content of the organic solvent is 15-70wt%; and the content of the lithium salt is 10-55wt%.

3. The ternary copolymer fluorinated acrylate gel polymer electrolyte according to claim 2, characterized in that, The ternary copolymer fluorinated acrylate has a number-average molecular weight of 1500~850000; and / or, The lithium salt is selected from at least one of lithium hexafluorophosphate and lithium bis(trifluoromethanesulfonyl)imide; and / or, The organic solvent is selected from at least one of fluoroethylene carbonate, propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, and methyl ethyl carbonate.

4. The ternary copolymer fluorinated acrylate gel polymer electrolyte according to claim 3, characterized in that, The number average molecular weight of the ternary copolymer fluorinated acrylate is 3,500 to 500,000.

5. A method for preparing the ternary copolymer fluorinated acrylate gel polymer electrolyte according to any one of claims 1 to 4, comprising: A precursor solution is obtained by stirring the components, including acrylate monomers containing alkyl carbonate groups, acrylate monomers containing ethylene carbonate groups, fluorinated acrylate monomers, lithium salts, and organic solvents, until homogeneous. Then, a polymerization reaction is carried out under the action of an initiator to obtain the ternary copolymer fluorinated acrylate gel polymer electrolyte.

6. The preparation method according to claim 5, characterized in that, The structural formula of the acrylate monomer containing alkyl carbonate groups is shown in formula (II): Formula (II) In equation (II), a is an integer between 0 and 4, b is an integer between 1 and 7, and c is an integer between 1 and 7; The structural formula of the acrylate monomer containing ethylene carbonate groups is shown in formula (Ⅲ): Formula (III) In equation (Ⅲ), d is an integer between 0 and 4, and e is an integer between 1 and 7; The structural formula of the fluorinated acrylate monomer is shown in formula (Ⅳ): Equation (Ⅳ) In formula (Ⅳ), f is an integer between 0 and 4, R1 is at least one of F and fluoroalkyl, and R2 and R3 are independently selected from at least one of H, F, alkyl and fluoroalkyl.

7. The preparation method according to claim 6, characterized in that, In the formula (Ⅱ), a is an integer between 0 and 3, b is an integer between 1 and 4, and c is an integer between 1 and 4; In the formula (Ⅲ), d is an integer between 0 and 3, and e is an integer between 1 and 4; In formula (Ⅳ), f is an integer between 0 and 3, R1 is at least one of F and fluorinated alkyl groups having 1 to 3 carbon atoms, and R2 and R3 are independently selected from at least one of H, F, alkyl groups having 1 to 3 carbon atoms, and fluorinated alkyl groups having 1 to 3 carbon atoms.

8. The preparation method according to claim 7, characterized in that, The fluorinated acrylate monomers are selected from at least one of 2-fluoromethacrylate, trifluoroethyl methacrylate, tetrafluoropropyl methacrylate, pentafluoropropyl 2,2,3,3,3-methacrylate, 2,2,2-trifluoroethyl acrylate, and 1,1,1,3,3,3-hexafluoroisopropyl acrylate; and / or, The initiator is selected from at least one of photoinitiators and thermal initiators; and / or, Based on a total weight of 100 wt% of the ternary copolymer fluorinated acrylate gel polymer electrolyte, the initiator is 0.15~4 wt%; and / or, The polymerization reaction conditions are as follows: polymerization initiated by ultraviolet light, with an ultraviolet light wavelength range of 100~500nm and an ultraviolet irradiation polymerization time of 2 minutes to 15 hours; or polymerization initiated by heat, with a polymerization temperature of 35~85℃ and a polymerization time of 4~55 hours.

9. The preparation method according to claim 8, characterized in that, The initiator is selected from at least one of 2-hydroxy-2-methyl-1-phenylpropanone, methyl benzoylcarbamate, 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2-methyl-2-(4-morpholino)-1-[4-(methylthio)phenyl]-1-propanone, azobisisobutyronitrile, dimethyl azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide; and / or, Based on a total weight of 100 wt% of the ternary copolymer fluorinated acrylate gel polymer electrolyte, the initiator is 0.25~1.25 wt%; and / or, The polymerization reaction conditions are as follows: polymerization initiated by ultraviolet light, with an ultraviolet lamp wavelength range of 150~400nm and an ultraviolet irradiation polymerization time of 5 minutes to 8 hours; or polymerization initiated by heat, with a polymerization temperature of 40~85℃ and a polymerization time of 6~24 hours.

10. The preparation method according to claim 9, characterized in that, The initiator is selected from at least one of azobisisobutyronitrile, methyl benzoate, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

11. The preparation method according to claim 5, characterized in that, The acrylate monomers containing alkyl carbonate groups are prepared by esterification of hydroxyalkyl acrylate compounds and alkyl chloroformate compounds under the action of alkaline compounds.

12. The preparation method according to claim 11, characterized in that, The structural formula of the acrylic-hydroxyalkyl ester compound is shown in formula (V): Formula (V) In equation (V), a is an integer between 0 and 4, and b is an integer between 1 and 7; and / or, The structural formula of the alkyl chloroformate compound is shown in formula (VI): Formula (VI) In equation (VI), c is an integer between 1 and 7; and / or, The molar ratio of the hydroxyalkyl acrylate compound and the alkyl chloroformate compound is 1:(0.85~1.5); and / or, The basic compound is selected from at least one of organic basic compounds; and / or, The molar ratio of the basic compound to the hydroxyalkyl acrylate compound is (1~3):1; and / or, The esterification reaction conditions are: under a protective gas atmosphere, at -10 to 5°C for 6 to 16 hours; and / or, The esterification reaction is carried out in a solvent.

13. The preparation method according to claim 12, characterized in that, In equation (V), a is an integer between 0 and 3, and b is an integer between 1 and 4; and / or, In equation (VI), c is an integer between 1 and 4; and / or, The molar ratio of the hydroxyalkyl acrylate compound and the alkyl chloroformate compound is 1:(1~1.3); and / or, The basic compound is selected from at least one of triethylamine and pyridine; and / or, The molar ratio of the basic compound to the hydroxyalkyl acrylate compound is (1~1.5):1; and / or, The esterification reaction conditions are: under a protective gas atmosphere, at -5 to 0°C for 8 to 14 hours; and / or, The solvent for the esterification reaction is selected from at least one of toluene, tetrahydrofuran, and dichloromethane.

14. The preparation method according to claim 5, characterized in that, The acrylate monomers containing ethylene carbonate groups are prepared by esterification of hydroxyalkyl dioxapentanone compounds and alkyl acryloyl chloride compounds under the action of alkaline compounds.

15. The preparation method according to claim 14, characterized in that, The structural formula of the hydroxyalkyl dioxapentane ketone compound is shown in formula (VII): Formula (VII) In equation (VII), e is an integer between 1 and 7; and / or, The structural formula of the alkyl acryloyl chloride compound is shown in formula (VIII): Formula (VIII) In equation (VIII), d is an integer between 0 and 4; and / or, The molar ratio of the hydroxyalkyl dioxapentane ketone compound and the alkyl acryloyl chloride compound is 1:(0.85~1.3); and / or, The basic compound is selected from at least one of organic basic compounds; and / or, The molar ratio of the basic compound to the hydroxyalkyl dioxapentanone compound is (1~3):1; and / or, The esterification reaction conditions are: under a protective gas atmosphere, at -10 to 5°C for 6 to 16 hours; and / or, The esterification reaction is carried out in a solvent.

16. The preparation method according to claim 15, characterized in that, In equation (VII), e is an integer between 1 and 4; and / or, In equation (VIII), d is an integer between 0 and 3; and / or, The molar ratio of the hydroxyalkyl dioxapentanone compound and the alkyl acryloyl chloride compound is 1:(1~1.3); and / or, The basic compound is selected from at least one of triethylamine and pyridine; and / or, The molar ratio of the basic compound to the hydroxyalkyldioxapentanone compound is (1~1.5):1; and / or, The esterification reaction conditions are: under a protective gas atmosphere, at -5 to 0°C for 8 to 14 hours; and / or, The solvent for the esterification reaction is selected from at least one of toluene, tetrahydrofuran, and dichloromethane.

17. A quasi-solid-state battery, comprising a negative electrode, a positive electrode, a separator, and a ternary copolymer fluorinated acrylate gel polymer electrolyte, wherein the ternary copolymer fluorinated acrylate gel polymer electrolyte is the ternary copolymer fluorinated acrylate gel polymer electrolyte according to any one of claims 1 to 4 or the ternary copolymer fluorinated acrylate gel polymer electrolyte obtained by the preparation method according to any one of claims 5 to 16.

18. The quasi-solid-state battery according to claim 17, characterized in that, The negative electrode is at least one of graphite, lithium titanate, lithium metal, graphite / silicon composite, silicon-based alloy, and tin-based alloy; and / or, The diaphragm is selected from at least one of polyethylene, polyvinylidene fluoride, polypropylene, polypropylene / polyethylene double-layer composite diaphragm, and polypropylene / polyethylene / polypropylene triple-layer composite diaphragm; and / or, The positive electrode includes a positive electrode active material, conductive carbon black, a binder, and a current collector.

19. The quasi-solid-state battery according to claim 18, characterized in that, The positive electrode active material is selected from at least one of lithium nickel cobalt aluminum oxide, lithium iron manganese phosphate, lithium iron phosphate, lithium manganese oxide, lithium nickel cobalt manganese oxide, and lithium cobalt oxide; and / or, the binder is selected from at least one of polyvinylidene fluoride, polyvinyl difluoride, polytetrafluoroethylene, polyvinyl alcohol, and polyurethane; and / or, the current collector is selected from at least one of aluminum foil and copper foil; and / or, based on the total weight of the positive electrode active material, conductive carbon black, and binder being 100wt%, the positive electrode active material is 50~95wt%, the conductive carbon black is 1~25wt%, and the binder is 4~25wt%.

20. A method for preparing a quasi-solid-state battery according to any one of claims 17-19, comprising: A precursor solution is obtained by uniformly mixing components including acrylate monomers containing alkyl carbonate groups, acrylate monomers containing ethylene carbonate groups, fluorinated acrylate monomers, lithium salts, initiators, and organic solvents. The precursor solution is injected into a battery assembled from a positive electrode, a negative electrode, and a separator. Polymerization is initiated inside the battery by heating to obtain a quasi-solid-state battery. or, A precursor solution is obtained by uniformly stirring components including acrylate monomers containing alkyl carbonate groups, acrylate monomers containing ethylene carbonate groups, fluorinated acrylate monomers, lithium salts, initiators, and organic solvents. The precursor solution is coated on a separator, and polymerization is carried out on the separator by heating or ultraviolet light initiation to obtain a quasi-solid-state electrolyte membrane. The membrane is then assembled with a positive electrode and a negative electrode to obtain a quasi-solid-state battery. or, A precursor solution is obtained by stirring a mixture of components including acrylate monomers containing alkyl carbonate groups, acrylate monomers containing ethylene carbonate groups, fluorinated acrylate monomers, lithium salts, initiators, and organic solvents. The precursor solution is then coated onto a positive electrode and / or a negative electrode, and polymerization is carried out on the positive electrode and / or a negative electrode by heating or ultraviolet light initiation to obtain a quasi-solid-state electrolyte composite positive electrode and / or a negative electrode. A quasi-solid-state battery is obtained by selecting the opposite electrodes of the positive electrode and / or a negative electrode and assembling the quasi-solid-state electrolyte membrane.

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