Fluorine-rich acrylate polymer material as well as preparation method and application thereof

Abstract

The invention discloses a fluorine-rich acrylate polymer material as well as a preparation method and application thereof, and relates to the technical field of new energy. According to the invention, methyl methacrylate is used as a skeleton, a fluorine-containing polymer monomer is used as a functional monomer, and a fluorine-rich acrylate polymer material is generated through a copolymerization reaction. While the characteristic that methyl methacrylate can be dissolved in an electrolyte is reserved, the hydrophobicity of a polymer is improved by introducing a fluorine-containing monomer, and the polymer is loaded on the surface of a pre-lithiated electrode through a spraying means, so that the environmental stability of the pre-lithiated electrode is improved. Compared with other conventional pre-lithiation electrode protection work, the polymer design scheme for pre-lithiation electrode protection has the advantages that lithium ion transmission and pre-lithiation performance are not affected, excellent environmental stability can be realized, the polymer design scheme is adaptive to an industrial production process, and meanwhile, the cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of new energy technology, and more specifically, to a fluorinated acrylate polymer material, its preparation method, and its application. Background Technology

[0002] In the process of promoting the development of electric vehicles and large-scale energy storage, the energy density and cycle life of lithium-ion batteries are key bottlenecks. During the first charge and discharge cycle, the formation of a solid electrolyte interface (SEI) on the negative electrode surface irreversibly consumes the active lithium in the positive electrode, leading to a decrease in initial coulombic efficiency and energy density loss. To compensate for this "first coulombic loss," pre-lithiation technology has emerged, which pre-adds lithium to the electrodes before battery assembly, becoming an effective strategy to improve the overall performance of the battery.

[0003] However, lithium-rich materials used as additives, pre-lithiated electrodes, and lithium metal foils are all extremely sensitive to water and oxygen in the environment, making them prone to deterioration and failure, leading to safety risks and process challenges. This severely hinders the industrial application of pre-lithiation technology. Currently, the industry mainly relies on strictly controlled dry environments for production and storage, but this significantly increases manufacturing costs and operational complexity.

[0004] Therefore, current efforts focus on developing various protection technologies to improve the air stability of pre-lithiated components. Existing protection strategies mainly follow two directions: one is to modify the surface of pre-lithiated powder materials to construct a core-shell structure or generate a protective layer through chemical reactions; the other is to cover the surface of the pre-lithiated electrode with a physical barrier layer. However, these methods have significant limitations. Powder protection processes are complex, and it is difficult to guarantee the uniformity and consistency of coating, and they are usually only applicable to materials with specific chemical systems. While a dense polymer protective layer directly coated on the electrode surface can isolate air, it may severely hinder lithium-ion transport, sacrificing the battery's rate performance and capacity utilization. Some methods that generate a protective layer in situ through chemical reactions may even irreversibly consume some of the pre-lithiated capacity, offsetting its lithium replenishment benefits.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a fluorinated acrylate polymer material, its preparation method, and its applications. This invention uses methyl methacrylate as a backbone and fluorinated polymer monomers as functional monomers to generate a fluorinated acrylate polymer material through a copolymerization reaction. Compared to other conventional pre-lithiation electrode protection methods, the polymer design scheme for pre-lithiation electrode protection does not affect lithium-ion transport or pre-lithiation performance, achieves excellent environmental stability, is compatible with industrial production processes, and reduces costs.

[0007] This invention is implemented as follows: In a first aspect, the present invention provides a method for preparing a fluorinated acrylate polymer material, comprising the following steps: A portion of the reaction solvent, methyl methacrylate, fluorine-rich monomer, and catalyst were mixed and stirred at high temperature to obtain the first mixture; The catalyst and the remaining reaction solvent were added to the first mixture, and the mixture was stirred continuously at high temperature to carry out the reaction. After the reaction was completed, the mixture was kept at a constant temperature and then cooled before being discharged. The reaction solvent was removed by evaporation to obtain a fluorinated acrylate polymer material.

[0008] In an optional embodiment, the reaction solvent comprises at least one of acetone, methyl isobutyl ketone, n-propyl acetate, cyclohexanone, isobutyl acetate, butyl acetate, isopropanol, ethanol, and n-butanol. And / or, the fluorine-rich monomer is at least one selected from the following: perfluorohexyl ethyl methacrylate, perfluorodecyl ethyl methacrylate, perfluorohexyl ethyl methacrylate, perfluorooctyl ethoxyethyl methacrylate, perfluorooctyl ethyl methacrylate, perfluorodecyl ethyl methacrylate, perfluorobutyl ethyl methacrylate, perfluorohexyl ethyl methacrylate, trifluoroethyl methacrylate, hexafluoroisopropyl methacrylate, hexafluorobutyl methacrylate, hexafluoroisopropyl methacrylate, trifluorotert-butyl methacrylate, perfluorooctyl ethoxyethyl methacrylate, perfluorooctyl ethyl thiomethyl methacrylate, and trifluoroethyl methacrylate. And / or, the catalyst is at least one of the following: dimethyl azobisisobutyrate, azobisisoheptanenitrile, azobiscyclohexylformonitrile, azobisisobutyronitrile, benzoyl peroxide, lauroyl peroxide, di(2-ethylhexyl) peroxide, dicyclohexyl peroxide, hydrogen peroxide, and persulfate.

[0009] In an optional embodiment, the molar ratio of the partial reaction solvent to the methyl methacrylate in the first mixture is 2.5 to 5.5; the molar ratio of the methyl methacrylate to the fluorinated monomer is 25.0 to 35.0; and the molar ratio of the methyl methacrylate to the catalyst is 10.5 to 14.5. And / or, the molar ratio of the remaining reaction solvent to the catalyst is 15-20.

[0010] In an optional embodiment, the stirring process uses a cantilevered electric stirrer with a speed of 100~1000 rpm and a stirring time of 2~12 h; the heat preservation temperature is 80~150℃ and the heat preservation time is 5~20 h; the cooling temperature is 20~50℃; and the volatile reaction solvent is evaporated at a constant temperature of 20~50℃ for 6~36 h.

[0011] Secondly, the present invention proposes a fluorinated acrylate polymer material prepared based on any of the above embodiments.

[0012] Thirdly, the present invention proposes the application of a fluorinated acrylate polymer material in a protective layer of a pre-lithiated electrode. The preparation method of the protective layer includes the following steps: stirring the fluorinated acrylate polymer and the spraying solvent evenly to obtain a second mixture; spraying the second mixture onto the surface of the pre-lithiated electrode to obtain a fluorinated acrylate polymer protective layer.

[0013] In an optional embodiment, the areal loading of the fluorinated acrylate polymer on the pre-lithiated electrode is 0.03~1.38 mg·cm⁻¹. -2 ; And / or, in the second mixture, the molar ratio of the spraying solvent to the fluorinated acrylate polymer is 5.0 to 10.0; And / or, the stirring process uses a cantilevered electric stirrer with a speed of 100~1000 rpm and a stirring time of 2~12 h.

[0014] In an optional embodiment, the pre-lithiation electrode is a pre-lithiation electrode prepared by electrochemical pre-lithiation, chemical pre-lithiation, pre-lithiation additives, and direct contact or short-circuit pre-lithiation with lithium metal foil. And / or, the pre-lithiation additive is at least one of lithium peroxide, lithium oxide, lithium nitride, lithium fluoride, lithium sulfide, lithium selenide, lithium silicon alloy, lithium aluminum alloy, lithium magnesium alloy, lithium ferrite, lithium nickel oxide, lithium cobalt oxide, lithium manganese oxide, and lithium oxalate. And / or, the electrode is a ternary lithium cathode, a lithium iron phosphate cathode, a lithium cobalt oxide cathode, a silicon-based anode, or a graphite anode.

[0015] In an optional embodiment, the spraying solvent is at least one selected from tetrahydrofuran, 2-methyltetrahydrofuran, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, 1,3-dioxolane, bis(2,2,2-trifluoroethyl) ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, tris(2,2,2-trifluoroethyl) phosphate, ethylene carbonate, propylene carbonate, fluoroethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dipropyl carbonate, ethyl acetate, and ethyl propionate.

[0016] In an optional embodiment, the fluorinated acrylate polymer is sprayed onto the surface of the pre-lithiated electrode using a spray gun. The spraying process is carried out at a temperature of 20~40℃, at a distance of 5~30 cm directly in front of the pre-lithiation electrode and 5~30 cm directly above the pre-lithiation electrode, with a spraying volume of 100~900 μL each time.

[0017] The present invention has the following beneficial effects: The pre-lithiation electrode protection technology provided by this invention has significant advantages. First, by introducing fluorinated hydrophobic groups into the acrylate polymer backbone through free radical copolymerization, the constructed protective layer possesses excellent hydrophobic properties, effectively blocking environmental moisture and ensuring the stability of the pre-lithiation electrode under high humidity conditions. This greatly relaxes the environmental requirements for electrode storage and assembly, and improves process adaptability. Second, this polymer protective layer can rapidly dissolve in carbonate-based electrolytes after battery filling. This characteristic is crucial: on the one hand, the dissolution process does not irreversibly consume the pre-lithiation capacity, ensuring the full realization of the lithium replenishment effect; on the other hand, the complete removal of the protective layer completely eliminates its physical hindrance to lithium-ion migration, ensuring the intrinsic ionic conductivity and electrochemical reaction kinetics of the electrode, thereby maintaining the battery's high capacity and excellent rate performance. In summary, this technology ingeniously integrates the functions of "pre-assembly stabilization protection" and "automatic elimination during operation," effectively solving the problem of air sensitivity in pre-lithiation electrodes while avoiding the inherent contradiction of traditional protection strategies damaging electrochemical performance. It provides an efficient and reliable path for the large-scale and safe application of pre-lithiation technology. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating the preparation process of fluorinated acrylate polymer materials in this embodiment of the invention. Figure 2 This is a flowchart illustrating the preparation process of the pre-lithiation electrode protective layer in an embodiment of the present invention. Figure 3 The nuclear magnetic fluorine spectrum of the fluorine-rich acrylate polymer material prepared in Example 1 of this invention; Figure 4 The Fourier transform infrared spectrum of the fluorinated acrylate polymer material prepared in Example 1 of this invention; Figure 5 This is a scanning electron microscope image of the fluorinated acrylate polymer material prepared in Example 1 of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0021] The following provides a detailed description of a fluorinated acrylate polymer material, its preparation method, and its applications.

[0022] In a first aspect, the present invention provides a method for preparing fluorinated acrylate polymer materials, such as... Figure 1 As shown, it includes the following steps: A portion of the reaction solvent, methyl methacrylate, fluorine-rich monomer, and catalyst were mixed and stirred at high temperature to obtain the first mixture; The catalyst and the remaining reaction solvent were added to the first mixture, and the mixture was stirred continuously at high temperature to carry out the reaction. After the reaction was completed, the mixture was kept at a constant temperature and then cooled before being discharged. The reaction solvent was removed by evaporation to obtain a fluorinated acrylate polymer material.

[0023] Among them, by using methyl methacrylate as the backbone and fluorinated polymer monomers as functional monomers, a fluorinated acrylate polymer material is generated through copolymerization. This material can retain the electrolyte solubility of methyl methacrylate while improving the hydrophobicity of the polymer by introducing fluorinated monomers.

[0024] In an optional embodiment, the reaction solvent comprises at least one of acetone, methyl isobutyl ketone, n-propyl acetate, cyclohexanone, isobutyl acetate, butyl acetate, isopropanol, ethanol, and n-butanol; preferably, the reaction solvent is butyl acetate.

[0025] In an optional embodiment, the fluorinated monomer is at least one selected from perfluorohexyl ethyl methacrylate, perfluorodecyl ethyl methacrylate, perfluorohexyl ethyl methacrylate, perfluorooctyl ethoxyethyl methacrylate, perfluorooctyl ethyl methacrylate, perfluorodecyl ethyl methacrylate, perfluorobutyl ethyl methacrylate, perfluorohexyl ethyl, trifluoroethyl methacrylate, hexafluoroisopropyl acrylate, hexafluorobutyl methacrylate, hexafluoroisopropyl methacrylate, trifluorotert-butyl methacrylate, perfluorooctyl ethoxyethyl methacrylate, perfluorooctyl ethyl thiomethyl methacrylate, and trifluoroethyl methacrylate; preferably, the fluorinated monomer is perfluorohexyl ethyl.

[0026] In an optional embodiment, the catalyst is at least one selected from dimethyl azobisisobutyrate, azobisisoheptanenitrile, azobiscyclohexylformonitrile, azobisisobutyronitrile, benzoyl peroxide, lauroyl peroxide, di(2-ethylhexyl) percarbonate, dicyclohexyl percarbonate, hydrogen peroxide, and persulfate. Preferably, the catalyst is azobisisobutyronitrile.

[0027] In an optional embodiment, the molar ratio of the partial reaction solvent and the methyl methacrylate in the first mixture is 2.5 to 5.5; The molar ratio of methyl methacrylate to the fluorinated monomer is 25.0~35.0; The molar ratio of methyl methacrylate to the catalyst is 10.5 to 14.5.

[0028] In an optional embodiment, the molar ratio of the remaining reaction solvent to the catalyst is 15-20.

[0029] In an optional embodiment, the stirring process uses a cantilevered electric stirrer with a rotation speed of 100~1000 rpm and a stirring time of 2~12 h; preferably, the rotation speed is 300 rpm and the stirring time is 2 h.

[0030] The insulation temperature is 80~150℃, and the insulation time is 5~20h; preferably, the insulation temperature is 90℃, and the insulation time is 2h.

[0031] The cooling temperature is 20~50℃; preferably, the cooling temperature is 30℃, and the material is discharged after cooling to this temperature.

[0032] The volatile reaction solvent is volatilized at a constant temperature of 20~50℃ for 6~36h; preferably, the volatile reaction solvent is volatilized at a constant temperature of 30℃ for 12h.

[0033] Secondly, the present invention proposes a fluorinated acrylate polymer material prepared based on any of the above embodiments.

[0034] Thirdly, this invention proposes the application of a fluorinated acrylate polymer material in a pre-lithiation electrode protective layer, the preparation method of which includes the following steps: Figure 2 As shown: The fluorinated acrylate polymer and the spraying solvent are stirred evenly to obtain a second mixture; the second mixture is sprayed onto the surface of the pre-lithiated electrode to obtain a fluorinated acrylate polymer protective layer.

[0035] This method involves coating a pre-lithiated electrode surface with a fluorinated acrylate polymer material via spraying to provide protection in high-humidity environments, thereby improving the environmental stability of the pre-lithiated electrode. Compared to other conventional pre-lithiated electrode protection methods, this polymer design for pre-lithiated electrode protection does not affect lithium-ion transport or pre-lithiation performance, achieves excellent environmental stability, is compatible with industrial production processes, and reduces costs.

[0036] Furthermore, the polymer-protected battery can be assembled according to normal procedures. Because the acrylate copolymer exhibits good wettability and dissolves in the battery's carbonate-based liquid electrolyte, the polymer layer designed in this work can gradually dissolve in the battery electrolyte without affecting the pre-lithiation capacity or lithium-ion migration rate. Based on the prepared fluorinated acrylate polymer material, the protective layer proposed in this invention has a dual function: (i) it effectively protects the pre-lithiation electrode from atmospheric moisture degradation, achieving excellent protection; (ii) it exhibits rapid dissolution kinetics in standard carbonate-based electrolytes, thereby ensuring unimpeded lithium-ion transfer during pre-lithiation without affecting the electrochemical performance of the pre-lithiation electrode.

[0037] In an optional embodiment, the areal loading of the fluorinated acrylate polymer on the pre-lithiated electrode is 0.03~1.38 mg·cm⁻¹. -2 .

[0038] In an optional embodiment, the molar ratio of the spraying solvent to the fluorinated acrylate polymer in the second mixture is 5.0 to 10.0.

[0039] In an optional embodiment, the stirring process uses a cantilevered electric stirrer with a rotation speed of 100~1000 rpm and a stirring time of 2~12 h; preferably, the rotation speed is 300 rpm and the stirring time is 2 h.

[0040] In an optional embodiment, the pre-lithiation electrode is a pre-lithiation electrode prepared by electrochemical pre-lithiation, chemical pre-lithiation, pre-lithiation additives, and direct contact or short-circuit pre-lithiation with lithium metal foil. Preferably, the pre-lithiation additive is at least one of lithium peroxide, lithium oxide, lithium nitride, lithium fluoride, lithium sulfide, lithium selenide, lithium silicon alloy, lithium aluminum alloy, lithium magnesium alloy, lithium ferrite, lithium nickel oxide, lithium cobalt oxide, lithium manganese oxide, and lithium oxalate; more preferably, the pre-lithiation electrode is pre-lithiated by using lithium silicon alloy as a pre-lithiation additive.

[0041] In optional embodiments, the electrode is a ternary lithium cathode, a lithium iron phosphate cathode, a lithium cobalt oxide cathode, a silicon-based anode, or a graphite anode; preferably, the electrode is a silicon-oxygen-carbon anode.

[0042] It should be noted that silicon-based anodes can be silicon anodes, silicon-oxygen anodes, or silicon-oxygen-carbon anodes, etc.

[0043] In an optional embodiment, the spraying solvent is at least one selected from tetrahydrofuran, 2-methyltetrahydrofuran, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, 1,3-dioxolane, bis(2,2,2-trifluoroethyl) ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, tris(2,2,2-trifluoroethyl) phosphate, ethylene carbonate, propylene carbonate, fluoroethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dipropyl carbonate, ethyl acetate, and ethyl propionate; preferably, the spraying solvent is 1,3-dioxolane.

[0044] In an optional embodiment, the fluorinated acrylate polymer is sprayed onto the surface of the pre-lithiated electrode using a spray gun. The spraying process is carried out at a temperature of 20~40℃, at a distance of 5~30 cm directly in front of the pre-lithiation electrode and at a distance of 5~30 cm directly above the pre-lithiation electrode, with a spraying volume of 100~900 μL each time. Preferably, the spraying process is at 30°C, and the spraying is performed at a distance of 8 cm in front of the pre-lithiation electrode and 4 cm above the pre-lithiation electrode, with each spraying amount being 500 μL.

[0045] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0046] Example 1 This embodiment provides a method for preparing fluorinated acrylate polymer materials, including the following steps: S1. Weigh 3 mol butyl acetate, 1 mol methyl methacrylate, 0.05 mol perfluorohexylethyl, and 0.06 mol azobisisobutyronitrile, and stir at 90 °C for 2 h to obtain the first mixture at a speed of 300 rpm.

[0047] S2. Weigh 0.5 mol butyl acetate and 0.03 mol azobisisobutyronitrile, add them to the first mixture, stir at 90 °C for 2 h and then stop stirring at 300 rpm; then keep at 90 °C for 2 h, cool to 30 °C and discharge, evaporate the reaction solvent to obtain fluorinated acrylate polymer material, the evaporation temperature is 30 °C and 12 h.

[0048] The fluorinated acrylate polymer material was examined by nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The results are as follows: Figure 3 , Figure 4 and Figure 5 As shown.

[0049] according to Figure 3 The results show that the characteristic chemical shift peaks appearing in the nitrogen NMR spectrum, such as 60 to Multiple signals within the 120 ppm range confirmed that the perfluorinated structural unit had been successfully incorporated into the polymer chain, indicating that the fluorinated monomers effectively participated in the copolymerization reaction. According to... Figure 4 The results show that Fourier transform infrared spectroscopy further supports this conclusion, at 1753 cm⁻¹. - The strong absorption peak near ¹ is attributed to the C=O stretching vibration, while the peak at 1167 cm⁻¹ is... - ¹ and 648 cm - The absorption at ¹ corresponds to C. The stretching and bending vibrations of the F bond, and the appearance of these characteristic peaks, clearly indicate the simultaneous presence of an acrylate backbone and fluorinated groups in the polymer. According to... Figure 5 The results show that, according to the scanning electron microscope combined with the elemental distribution map, fluorine is uniformly distributed in the polymer, indicating that the fluorinated monomers are well dispersed in the polymer matrix during the copolymerization process and no obvious phase separation occurs. This is beneficial for the subsequent formation of a uniform and dense protective layer.

[0050] This embodiment also provides a fluorinated acrylate polymer material protective layer, which uses a lithium-silicon alloy as a pre-lithiation additive and a silicon-oxygen-carbon negative electrode as an electrode to prepare a pre-lithiation electrode. The fluorinated acrylate polymer is loaded onto the surface of the pre-lithiation electrode by spraying.

[0051] Its preparation method includes the following steps: S1. Weigh 1 mol of fluorinated acrylate polymer and 5 mol of 1,3-dioxolane, and stir at room temperature for 2 h to obtain a second mixture at a speed of 300 rpm.

[0052] S2. The second mixture is sprayed onto the surface of the pre-lithiated electrode using a spray gun to obtain the fluorinated acrylate polymer protective layer. The spraying temperature is 30°C, and the spraying is performed at a distance of 8 cm in front of and 4 cm above the pre-lithiated electrode. The spraying volume is 500 μL per coat, and the surface loading of the fluorinated acrylate polymer on the pre-lithiated electrode is 0.03~1.38 mg·cm³. -2 .

[0053] Examples 2-129 Examples 2 through 129 disclose a series of fluorinated acrylate polymer materials, which differ from Example 1 in the type and amount of fluorinated monomers used. All other experimental parameters and procedures are the same as in Example 1. The types and amounts of fluorinated monomers used in Examples 2 through 129 are detailed in Table 1 below.

[0054] Examples 2 to 129 also disclose a series of battery pre-lithiation protection negative electrodes, which differ from Example 1 only in that the battery pre-lithiation protection negative electrodes of Examples 2 to 129 respectively correspond to the fluorinated acrylate polymer materials prepared in Examples 2 to 129.

[0055] Examples 130-165 Examples 130-165 disclose a series of fluorinated acrylate polymer materials, which differ from Example 1 in the type and amount of catalyst and reaction solvent. All other experimental parameters and procedures are the same as in Example 1. The type and amount of catalyst and reaction solvent in Examples 130-165 are detailed in Table 2 below.

[0056] Examples 130-165 also disclose a series of battery pre-lithiation protection anodes, which differ from Example 1 only in that the battery pre-lithiation protection anodes in Examples 130-165 respectively correspond to the fluorinated acrylate polymer materials prepared in Examples 130-165.

[0057] Examples 166-172 Examples 166-172 disclose a series of fluorinated acrylate polymer materials, which differ from Example 1 in that they have different reaction temperatures and heat preservation regimes. All other experimental parameters and procedures are the same as in Example 1. The reaction temperatures in Examples 166-172 are detailed in Table 3 below.

[0058] Examples 166-172 also disclose a series of battery pre-lithiation protection negative electrodes, which differ from Example 1 only in that the battery pre-lithiation protection negative electrodes of Examples 166-172 respectively correspond to the fluorinated acrylate polymer material prepared in Examples 166-172.

[0059] Examples 173-194 Examples 173-194 disclose a series of pre-lithiation protected negative electrodes, which differ from Example 1 in the type and amount of the spraying solvent. The remaining experimental parameters and procedures are the same as in Example 1. The types and amounts of the spraying solvent and reaction solvent in Examples 173-194 are detailed in Table 4 below.

[0060] Examples 173-194 also disclose a series of battery pre-lithiation protection anodes, which differ from Example 1 only in that the battery pre-lithiation protection anodes of Examples 173-194 respectively correspond to the fluorinated acrylate polymer materials prepared in Examples 173-194.

[0061] Examples 195-202 Examples 195-202 disclose a series of pre-lithiation protected negative electrodes, which differ from Example 1 in the amount of fluorinated acrylate polymer used for spraying. All other experimental parameters and procedures are the same as in Example 1. The amount of fluorinated acrylate polymer used for spraying in Examples 195-202 is detailed in Table 5 below.

[0062] Examples 195-202 also disclose a series of battery pre-lithiation protection anodes, which differ from Example 1 only in that the battery pre-lithiation protection anodes of Examples 195-202 respectively include the fluorinated acrylate polymer material prepared in Examples 195-202.

[0063] Comparative Example 1 This comparative example provides a method for preparing a fluorinated acrylate polymer material, including the following steps: S1. Weigh 3 mol butyl acetate, 1 mol methyl methacrylate, and 0.06 mol azobisisobutyronitrile, and stir at 90 °C for 2 h to obtain the first mixture at a speed of 300 rpm.

[0064] S2. Weigh 0.5 mol butyl acetate and 0.03 mol azobisisobutyronitrile, add them to mixture 1, stir at 90 ℃ for 2 h and then stop stirring at 300 rpm; then keep at 90 ℃ for 2 h, cool to 30 ℃ and discharge the material, evaporate the reaction solvent to obtain fluorinated acrylate polymer material, the evaporation temperature is 30 ℃ and 12 h.

[0065] Furthermore, this comparative example also provides a fluorinated acrylate polymer material protective layer, which uses a lithium-silicon alloy as a pre-lithiation additive and a silicon-oxygen-carbon negative electrode as an electrode to prepare a pre-lithiation electrode, and loads the acrylate polymer onto the surface of the pre-lithiation electrode by spraying.

[0066] Its preparation method includes the following steps: S1. Weigh 1 mol of acrylate polymer and 5 mol of spraying solvent, and stir at room temperature for 2 h to obtain a second mixture at a speed of 300 rpm.

[0067] S2. The second mixture is sprayed onto the surface of the pre-lithiated electrode using a spray gun to obtain the acrylate polymer protective layer. The spraying temperature is 30°C, and the spraying is performed at a distance of 8 cm in front of and 4 cm above the pre-lithiated electrode. The spraying volume is 500 μL per coat, and the surface loading of the acrylate polymer on the pre-lithiated electrode is 0.03~1.38 mg·cm³. -2 .

[0068] Test case This experimental example tested the performance of the half-cells in each embodiment and comparative example, specifically including: The preparation process of a lithium-ion half-cell is as follows: Negative electrode: The pre-lithiation protected negative electrode prepared in Examples 1-202 is provided. A negative electrode active material is formed by adding N-methylpyrrolidone to a silicon-oxygen carbon material, conductive carbon black, and polyvinylidene fluoride (mass ratio 7:2:1). The negative electrode current collector, a single-sided copper foil (8 μm thick), is cleaned. Then, the negative electrode active material is uniformly coated onto the surface of the negative electrode current collector (coating thickness 50 μm). After the negative electrode active material layer is completely dry, it is cut to obtain the battery negative electrode of the required size. Counter electrode: Lithium metal sheet (thickness 400~500 μm); Electrolyte: 1 mol / L ethylene carbonate: diethyl carbonate (1:1) with 5% fluoroethylene carbonate added; Assembly (assembling a half-cell according to lithium-ion battery assembly) includes: assembling a pre-lithiated protective negative electrode and a counter electrode, and injecting electrolyte to obtain a half-cell. The half-cells obtained in Examples 1-202 are numbered B1-B202 sequentially, and the half-cell obtained in Comparative Example 1 is numbered C1. The electrodes of Examples 1-202 and Comparative Example 1 were placed in a humid environment (relative humidity 90%) for 3 days, and then lithium-ion half-cells were assembled for performance testing. The specific capacity (mAh / g) of the battery at 0.1C (1C=1500 mA / g) was tested. It can be seen that: after being stored in a humid environment (relative humidity 90%) for 3 days, the specific capacity of the pre-lithiated protective negative electrode based on fluorinated acrylate polymer at 0.1C can reach as high as 1437 mAh / g. After 100 cycles at 0.1C, the capacity retention rate is 46%, which is better than that of Comparative Example 1 (0.1C, 56 mAh / g; due to electrode failure, the capacity retention rate after cycling cannot be discussed in this case). The pre-lithiation protected negative electrode prepared by this invention exhibits long-term structural stability in humid environments and retains excellent capacity and rate performance in lithium-ion half-cells even after humidification. Specific test results are as follows: Table 1. Performance test results of Examples 2-129

[0069] Table 2. Performance test results of Examples 130-165

[0070] Table 3. Performance test results of Examples 166-172

[0071] Table 4. Performance test results of Examples 173-194

[0072] Table 5. Performance test results of Examples 195-202

[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a fluorinated acrylate polymer material, characterized in that, Includes the following steps: A portion of the reaction solvent, methyl methacrylate, fluorine-rich monomer, and catalyst were mixed and stirred at high temperature to obtain the first mixture; The catalyst and the remaining reaction solvent were added to the first mixture, and the mixture was stirred continuously at high temperature to carry out the reaction. After the reaction was completed, the mixture was kept at a constant temperature and then cooled before being discharged. The reaction solvent was removed by evaporation to obtain a fluorinated acrylate polymer material.

2. The method for preparing a fluorinated acrylate polymer material according to claim 1, characterized in that, The reaction solvent comprises at least one of acetone, methyl isobutyl ketone, n-propyl acetate, cyclohexanone, isobutyl acetate, butyl acetate, isopropanol, ethanol, and n-butanol; And / or, the fluorine-rich monomer is at least one selected from the following: perfluorohexyl ethyl methacrylate, perfluorodecyl ethyl methacrylate, perfluorohexyl ethyl methacrylate, perfluorooctyl ethoxyethyl methacrylate, perfluorooctyl ethyl methacrylate, perfluorodecyl ethyl methacrylate, perfluorobutyl ethyl methacrylate, perfluorohexyl ethyl methacrylate, trifluoroethyl methacrylate, hexafluoroisopropyl methacrylate, hexafluorobutyl methacrylate, hexafluoroisopropyl methacrylate, trifluorotert-butyl methacrylate, perfluorooctyl ethoxyethyl methacrylate, perfluorooctyl ethyl thiomethyl methacrylate, and trifluoroethyl methacrylate. And / or, the catalyst is at least one of the following: dimethyl azobisisobutyrate, azobisisoheptanenitrile, azobiscyclohexylformonitrile, azobisisobutyronitrile, benzoyl peroxide, lauroyl peroxide, di(2-ethylhexyl) peroxide, dicyclohexyl peroxide, hydrogen peroxide, and persulfate.

3. The method for preparing a fluorinated acrylate polymer material according to claim 1, characterized in that, The molar ratio of the reaction solvent and the methyl methacrylate in the first mixture is 2.5 to 5.5; the molar ratio of the methyl methacrylate and the fluorinated monomer is 25.0 to 35.0; and the molar ratio of the methyl methacrylate and the catalyst is 10.5 to 14.

5. And / or, the molar ratio of the remaining reaction solvent to the catalyst is 15-20.

4. The method for preparing a fluorinated acrylate polymer material according to claim 1, characterized in that, The stirring process uses a cantilevered electric stirrer with a speed of 100~1000 rpm and a stirring time of 2~12 h; the heat preservation temperature is 80~150℃ and the heat preservation time is 5~20 h; the cooling temperature is 20~50℃; and the volatile reaction solvent is volatilized at a constant temperature of 20~50℃ for 6~36 h.

5. A fluorinated acrylate polymer material prepared by the method according to any one of claims 1-4.

6. The application of the fluorinated acrylate polymer material as described in claim 5 in a pre-lithiation electrode protective layer, characterized in that, The method for preparing the protective layer includes the following steps: mixing the fluorinated acrylate polymer with a spraying solvent to obtain a second mixture; spraying the second mixture onto the surface of the pre-lithiated electrode to obtain a fluorinated acrylate polymer protective layer.

7. The application according to claim 6, characterized in that, The areal loading of the fluorinated acrylate polymer on the pre-lithiated electrode is 0.03~1.38 mg·cm⁻¹. -2 ; And / or, in the second mixture, the molar ratio of the spraying solvent to the fluorinated acrylate polymer is 5.0 to 10.0; And / or, the stirring process uses a cantilevered electric stirrer with a speed of 100~1000 rpm and a stirring time of 2~12h.

8. The application according to claim 6, characterized in that, The pre-lithiation electrode is a pre-lithiation electrode prepared by electrochemical pre-lithiation, chemical pre-lithiation, pre-lithiation additives, and direct contact or short-circuit pre-lithiation with lithium metal foil. And / or, the pre-lithiation additive is at least one of lithium peroxide, lithium oxide, lithium nitride, lithium fluoride, lithium sulfide, lithium selenide, lithium silicon alloy, lithium aluminum alloy, lithium magnesium alloy, lithium ferrite, lithium nickel oxide, lithium cobalt oxide, lithium manganese oxide, and lithium oxalate. And / or, the electrode is a ternary lithium cathode, a lithium iron phosphate cathode, a lithium cobalt oxide cathode, a silicon-based anode, or a graphite anode.

9. The application according to claim 6, characterized in that, The spraying solvent is at least one selected from tetrahydrofuran, 2-methyltetrahydrofuran, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, 1,3-dioxolane, bis(2,2,2-trifluoroethyl) ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, tris(2,2,2-trifluoroethyl) phosphate, ethylene carbonate, propylene carbonate, fluoroethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dipropyl carbonate, ethyl acetate, and ethyl propionate.

10. The application according to claim 6, characterized in that, The fluorinated acrylate polymer is sprayed onto the surface of the pre-lithiated electrode using a spray gun. The spraying process is carried out at a temperature of 20~40℃, at a distance of 5~30 cm directly in front of the pre-lithiation electrode and 5~30 cm directly above the pre-lithiation electrode, with a spraying volume of 100~900 μL each time.

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