A fluoropolymer solid-state electrolyte and a method of making the same

Abstract

The application provides a fluorine-containing polymer solid electrolyte and a preparation method thereof, and relates to the technical field of lithium batteries.The fluorine-containing polymer solid electrolyte comprises a fluorine-containing polymer and a conductive lithium salt; the fluorine-containing polymer is polymerized from raw materials comprising vinyl tris(2-methoxyethoxy)silane, p-trifluoromethyl styrene, vinyl ethylene carbonate and a crosslinking agent. The fluorine-containing polymer solid electrolyte utilizes a flexible siloxane chain and a rigid benzene ring to construct a rigid-flexible network, and gives consideration to excellent elasticity, ionic conductivity and mechanical strength required for inhibiting lithium dendrites. Meanwhile, the strong electron-withdrawing effect of the trifluoromethyl group promotes lithium salt dissociation, improves lithium ion transference number, and the fluorine-containing group significantly enhances the oxidation resistance and flame retardance, so that the unity of high safety and excellent electrochemical performance is realized.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and more specifically, to a fluoropolymer solid electrolyte and its preparation method. Background Technology

[0002] With the increasing demand for wearable devices, smart grids, and electric vehicles, human society is placing higher energy density requirements on power and energy storage devices. Limited by the 372mAh g / L graphite anode... -1 With its theoretical capacity, current lithium-ion batteries are struggling to meet the ever-increasing demand. In contrast, lithium metal boasts a capacity as high as 3860 mAh g⁻¹. -1 With its theoretical capacity, lithium metal batteries (LMBs) assembled with lithium metal as the negative electrode are expected to effectively address people's demand for high-energy-density energy storage devices and become an important development direction for the next generation of high-energy batteries.

[0003] However, traditional organic liquid electrolytes typically use low-flash-point, flammable carbonate solvents. This is not only a major reason why lithium metal block batteries (LMBs) cannot achieve higher energy densities and longer operating lives, but also poses serious safety hazards, limiting their widespread application. To address safety concerns, solvent-free solid electrolytes are considered the most suitable electrolyte choice for high-energy-density LMBs due to their excellent thermal and electrochemical stability. Among them, polycarbonate polymer electrolytes, such as polyethylene carbonate (PVEC), have attracted much attention due to their high oxidative decomposition potential. Furthermore, solid electrolytes themselves possess high safety, a wide electrochemical stability window, and good mechanical properties, theoretically capable of effectively suppressing lithium dendrite growth.

[0004] Despite the advantages mentioned above, existing polycarbonate electrolytes still have significant drawbacks in practical applications. First, their low ionic conductivity at room temperature limits the rate performance of batteries. Second, although safety is improved compared to liquid electrolytes, the flame retardancy of traditional carbonate-based frameworks remains poor, making it difficult to meet safety challenges under extreme conditions. Furthermore, the poor physical contact between the solid electrolyte and the solid electrode leads to significant interfacial impedance, severely impacting electrochemical performance. While existing technologies attempt to improve mechanical properties and interfacial compatibility through physical and chemical crosslinking, grafting, and the addition of inorganic fillers or film-forming additives, it is often difficult to simultaneously achieve high ionic conductivity, excellent mechanical strength, and good flame retardancy.

[0005] In summary, current lithium-ion battery electrolyte technology struggles to achieve a balance between safety, electrochemical performance, and interfacial stability. Traditional liquid electrolytes pose a flammability risk, while existing solid polymer electrolytes suffer from low room-temperature conductivity, poor interfacial contact, and insufficient flame retardancy due to their inherent material structure. Developing an electrolyte system that maintains high oxidative stability and mechanical strength, significantly improves ionic conductivity and interfacial contact, and simultaneously possesses excellent flame retardant properties is a critical technical challenge that urgently needs to be addressed in this field.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a fluoropolymer solid electrolyte and its preparation method. The fluoropolymer solid electrolyte utilizes a flexible siloxane chain and a rigid benzene ring to construct a network that combines rigidity and flexibility to balance mechanical properties and the ability to suppress lithium dendrites. At the same time, it utilizes the strong electron-withdrawing effect of trifluoromethyl groups to promote lithium salt dissociation, improve ionic conductivity, and enhance antioxidant and flame retardant properties.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a fluoropolymer solid electrolyte, wherein the fluoropolymer solid electrolyte comprises a fluoropolymer and a conductive lithium salt; The fluoropolymer is polymerized from raw materials including vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, ethylene carbonate, and a crosslinking agent.

[0009] In an optional embodiment, the conductive lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium difluorooxalate borate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, and lithium bis(trifluoromethanesulfonyl)imide.

[0010] In an optional embodiment, the crosslinking agent comprises trimethylolpropane trimethacrylate.

[0011] In an optional embodiment, the mass ratio of vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, and ethylene carbonate is (1~8):(1~6):(1~6).

[0012] In an optional embodiment, the mass of the conductive lithium salt is 10% to 50% based on the total mass of the monomers; and / or, the mass of the crosslinking agent is 0.5% to 2%.

[0013] In an optional embodiment, the raw material further includes a photoinitiator; Preferably, the photoinitiator comprises one or more of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2-hydroxy-2-methyl-1-phenylpropanone, and benzoyl peroxide; Preferably, the mass of the photoinitiator is 0.1% to 1% based on the total mass of the monomers.

[0014] Secondly, the present invention provides a method for preparing a fluoropolymer solid electrolyte as described in any of the foregoing embodiments, comprising: The vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, ethylene carbonate and the crosslinking agent are mixed, and the conductive lithium salt and photoinitiator are added. The mixture is stirred until the solids are completely dissolved. The polymerization reaction was carried out under ultraviolet light to obtain the fluoropolymer solid electrolyte.

[0015] In some embodiments, the wavelength of the ultraviolet light is 254 nm or 365 nm; and / or, The polymerization reaction takes 10 to 30 minutes; and / or, Before the ultraviolet light polymerization reaction, the method further includes: coating or dripping the mixed material onto the surface of the positive or negative electrode sheet; the ultraviolet light polymerization reaction is carried out in situ on the surface of the positive or negative electrode sheet to form the fluorinated polymer solid electrolyte on the surface.

[0016] Thirdly, the present invention provides a battery comprising a fluoropolymer solid electrolyte as described in any of the foregoing embodiments; or comprising a fluoropolymer solid electrolyte prepared by the preparation method described in the foregoing embodiments. Preferably, the battery further includes a lithium battery electrolyte; the lithium battery electrolyte wets the surface of the fluoropolymer solid electrolyte; Preferably, the battery is a lithium metal battery; the negative electrode of the battery comprises metallic lithium.

[0017] Fourthly, the present invention provides an electrical device including a battery as described in the foregoing embodiments.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: The fluoropolymer solid electrolyte is constructed by polymerizing vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, ethylene carbonate, and a crosslinking agent to create a rigid-flexible polymer network structure. Vinyltris(2-methoxyethoxy)silane introduces flexible siloxane chains, which effectively modulate the polymer's mechanical properties, giving it good elastic deformation capabilities and improving the ionic conductivity of the polymer matrix. Simultaneously, p-trifluoromethylstyrene introduces a rigid benzene ring structure, which significantly enhances the mechanical strength of the solid electrolyte, effectively physically blocking and inhibiting the formation and growth of lithium dendrites, thereby improving battery safety and long-cycle performance.

[0019] Furthermore, this solid-state electrolyte utilizes the unique chemical properties of the trifluoromethyl group (-CF3) in trifluoromethylstyrene. The trifluoromethyl group exhibits a strong electron-withdrawing effect, significantly weakening the electrostatic forces between lithium ions and anions in conductive lithium salts (such as lithium bis(trifluoromethanesulfonylimide),) thereby promoting lithium salt dissociation. This mechanism increases the concentration of free lithium ions in the system, enhancing lithium ion transference number and ionic conductivity. Simultaneously, the high bond energy of the fluorinated functional group endows the polymer with higher oxidation stability and flame retardant properties, resulting in a wider electrochemical stability window for the electrolyte at high voltages, further enhancing the battery's oxidation resistance and safety in high-energy-density applications. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the synthesis of fluoropolymers; Figure 2 The infrared spectra of Example 4, the monomer, and the lithium salt are shown below; Figure 3 Examples 4 and their optical images showing bending, folding, and restoration; Figure 4 Figure 4 shows the combustion test results of lithium battery electrolytes of different volumes after being slightly wetted in Example 4; Figure 5 Figure 1 shows the ionic conductivity test results of SS||SS (stainless steel||stainless steel) symmetric cells in Examples 1-5. Figure 6Electrochemical impedance spectroscopy and activation energy obtained by fitting SS||SS symmetric cells at different temperatures in Comparative Example 1 and Example 4; Figure 7 Figures showing the tensile test results for Comparative Example 1 and Example 4; Figure 8 The graph shows the lithium-ion transference number test results for the Li||Li symmetric battery in Example 4. Figure 9 The graph shows the lithium-ion transference number test results of the Li||Li symmetric cell in the comparative example. Figure 10 Tafel curves for Li||Li symmetric cells in Example 4 and Comparative Example 1; Figure 11 The lithium plating / delithiation voltage curves of Li||Li symmetric cells in Example 4 and Comparative Example 1 are shown. Figure 12 The graph shows the linear sweep voltammetry results of the Li / SS half-cell in Example 4 and Comparative Example 1. Figure 13 The HOMO and LUMO plots are obtained from DFT theoretical calculations; Figure 14 This is a diagram of the binding energy of a molecule to a lithium ion, calculated using DFT theory. Figure 15 The graph shows the cycling results of the LCO / Li half-cell in Comparative Example 1 and Example 4. Figure 16 The charge-discharge curves of the LCO / Li half-cell in Example 4 are shown for the 3rd, 50th, 100th, 150th, 200th, and 300th cycles. Figure 17 The charge-discharge curves of the LCO / Li half-cell in Comparative Example 1 are shown for the 3rd, 50th, 75th, 100th, and 150th cycles. Figure 18 The rate performance graphs of LCO / Li half-cells in Comparative Example 1 and Example 4 are shown. Figure 19 Cross-sectional SEM images of the lithium anode of the LCO / Li half-cell after 150 cycles in Comparative Example 1 and 300 cycles in Example 4. Figure 20 SEM images of the polymer solid electrolyte for the LCO / Li half-cell before and after 150 cycles in Comparative Example 1 and before and after 300 cycles in Example 4. Figure 21 TEM images of the LCO cathode after no cycling, after 150 cycles in Comparative Example 1, and after 300 cycles in Example 4; Figure 22XPS test comparison graph of LCO positive electrode after 150 cycles in Comparative Example 1 and 300 cycles in Example 4. Detailed Implementation

[0022] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0023] This application provides a fluoropolymer solid electrolyte, which includes a fluoropolymer and a conductive lithium salt; the fluoropolymer is polymerized from raw materials including vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, ethylene carbonate and a crosslinking agent.

[0024] The aforementioned fluoropolymer solid electrolyte is an ion conductor material used in batteries, and its physical state is solid. It is composed of a fluoropolymer as the matrix (host) and a conductive lithium salt as the active ingredient.

[0025] The aforementioned conductive lithium salt provides lithium ions (Li... + The source material is dispersed or dissolved in the polymer matrix to achieve ion transport and conductivity.

[0026] The aforementioned fluoropolymer is a macromolecular network structure formed by polymerization of specific raw materials (vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, ethylene carbonate and crosslinking agent) as defined in the foregoing embodiments, serving as the backbone of the solid electrolyte.

[0027] The above monomer combination constructs a polymer network structure that combines rigidity and flexibility, with each component functioning based on the following principles: Vinyltris(2-methoxyethoxy)silane, as a monomer providing flexible chain segments, contains siloxane chains with high flexibility in its molecular structure. Introducing flexible siloxane chains into the polymer network can adjust the mechanical properties of the polymer and endow the electrolyte with good elastic deformation ability; at the same time, the movement of the flexible chain segments helps to promote lithium ion transport, thereby improving the ionic conductivity of the electrolyte.

[0028] The aforementioned trifluoromethylstyrene serves as a monomer providing a rigid structure and fluorinated functional groups. It introduces a rigid "benzene ring structure" and a "trifluoromethyl (-CF3)" group with a strong electron-withdrawing effect. The rigid benzene ring structure enhances the mechanical strength of the polymer matrix, enabling it to physically suppress lithium dendrite growth and prevent battery short circuits; the strong electron-withdrawing effect of the -CF3 group weakens the cations (Li) in conductive lithium salts. + The electrostatic interaction between the lithium salt and anions promotes the dissociation of more free lithium ions, thereby significantly improving ionic conductivity and lithium ion transference number; the high bond energy of the fluorine-containing groups endows the material with higher antioxidant capacity and flame retardant properties, and broadens the electrochemical stability window.

[0029] The aforementioned ethylene carbonate, as a comonomer, participates in polymerization and helps to form the main chain backbone of carbonate polymers.

[0030] The aforementioned crosslinking agent is a substance that enables chemical bonds to form between linear polymer chains. Through crosslinking, the molecular chains formed by the monomers are connected into a three-dimensional network structure, ensuring that the electrolyte forms a stable solid state and further enhancing its mechanical strength and thermal stability.

[0031] In summary, the fluoropolymer solid electrolyte provided in this embodiment, through the synergistic effect of the aforementioned raw materials, forms a polymer network at the microscopic level that combines "rigid benzene rings" and "flexible siloxane chains." This structure ensures both the high mechanical strength required to suppress lithium dendrites and excellent ion transport capabilities and elasticity. Simultaneously, by utilizing the electrochemical properties of the fluorine-containing groups, it achieves high ionic conductivity, high lithium-ion transference number, and excellent antioxidant and flame-retardant safety performance.

[0032] In some embodiments, the conductive lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium difluorooxalate borate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, and lithium bis(trifluoromethanesulfonyl)imide.

[0033] This embodiment provides the specific chemical composition of conductive lithium salts dispersed in a polymer matrix. These salts include at least one of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium difluorooxalateborate (LiDFOB), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), and lithium bis(fluorosulfonyl)imide (LiFSI).

[0034] The fluoropolymer contains p-trifluoromethylstyrene, a monomer that introduces a trifluoromethyl (-CF3) group with a strong electron-withdrawing effect. When the conductive lithium salt (e.g., lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)) is present in the polymer network, the strong electron-withdrawing group (-CF3) on the polymer chain can significantly weaken the lithium ion concentration in the lithium salt. + These substances are lithium ion donors and act as electrolyte salts in solid electrolytes, responsible for dissociation and charge transfer within the fluoropolymer matrix.

[0035] This weakening of electrostatic interaction effectively increases the degree of lithium salt dissociation, causing more lithium salt molecules to separate into freely moving lithium ions and anions.

[0036] In this solid electrolyte, the concentration of free lithium ions in the system increases due to the promoting effect of lithium salt dissociation, thereby significantly improving the ionic conductivity and lithium ion transference number of the solid electrolyte (for example, the lithium ion transference number mentioned in the example can reach 0.68). The combination of these lithium salts with the fluoropolymer matrix helps to construct an electrolyte system with high oxidation stability and a wide electrochemical window, thereby improving the overall cycle stability and rate performance of the battery.

[0037] In some embodiments, the crosslinking agent includes trimethylolpropane trimethacrylate (TMPTMA).

[0038] TMPTMA molecules contain three polymerizable double bonds. Under ultraviolet light initiation, it can copolymerize with the monomers described in the aforementioned embodiments (vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, and ethylene carbonate). Due to its multifunctional properties, it can act as a "bridge" to connect different polymer molecular chains, thereby forming a dense three-dimensional network structure.

[0039] Using TMPTMA as a crosslinking agent ensures that the reaction system is completely transformed from a liquid precursor to a solid electrolyte, giving the material the necessary morphological stability. The crosslinking effect significantly enhances the mechanical strength of the polymer network, enabling it to be used as a self-supporting membrane and effectively blocking lithium dendrite penetration.

[0040] In some embodiments, the mass ratio of vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, and ethylene carbonate is (1~8):(1~6):(1~6).

[0041] The aforementioned vinyltris(2-methoxyethoxy)silane (1-8 parts), for example, can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, etc., mainly providing flexible siloxane chains. Within this range, a higher content helps to improve the material's elastic deformation capacity and ionic conductivity, preventing the material from becoming too brittle.

[0042] The aforementioned trifluoromethylstyrene (1-6 parts), for example, can be 1 part, 1.5 parts, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, etc., mainly provides rigid benzene rings and fluorine-containing groups. Within this range, sufficient mechanical strength is ensured to suppress dendrites, while providing sufficient electron-withdrawing groups to promote lithium salt dissociation and improve antioxidant / flame retardant properties.

[0043] The aforementioned ethylene ethylene carbonate (1~6), for example, can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 5.5 parts, 6 parts, etc., as a basic carbonate backbone, to synergistically construct the polymer backbone.

[0044] This ratio range ensures that the solid electrolyte has both high ionic conductivity, high mechanical strength (tensile strength) and excellent interfacial stability, avoiding performance shortcomings (such as low conductivity or insufficient mechanical strength) caused by too little or too much of a certain monomer.

[0045] In some embodiments, the mass of the conductive lithium salt is 10% to 50% based on the total mass of the monomers (e.g., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, etc.). Within this range, combined with the dissociation-promoting properties of the fluoropolymer, optimal ionic conductivity and lithium-ion transference number can be obtained while maintaining good film-forming properties of the polymer. And / or, the mass of the crosslinking agent is 0.5% to 2% (e.g., 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, 1.6%, 1.8%, 2.0%, etc.). This range ensures that the monomers are completely cured to form a solid electrolyte with sufficient strength, while avoiding excessive crosslinking that could lead to brittle material or obstruction of internal ion transport channels, thus balancing mechanical and electrochemical properties.

[0046] In some embodiments, the raw material further includes a photoinitiator; Preferably, the photoinitiator comprises one or more of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2-hydroxy-2-methyl-1-phenylpropanone, and benzoyl peroxide; Preferably, the mass of the photoinitiator is 0.1% to 1% based on the total mass of the monomers.

[0047] This is a photosensitive compound that can undergo a chemical change after absorbing light energy of a specific wavelength (such as ultraviolet light), producing reactive intermediates (such as free radicals).

[0048] This embodiment provides a variety of photoinitiators, including one or more of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), ethyl 2,4,6-trimethylbenzoylphenylphosphonate (TPO-L), 2-hydroxy-2-methyl-1-phenylpropanone (1173), and benzoyl peroxide (BPO).

[0049] The fluoropolymer is polymerized from monomers containing unsaturated double bonds (vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene) and crosslinking agents (such as TMPTMA). The photoinitiator functions by absorbing light energy and decomposing to generate highly reactive free radicals when the mixture is exposed to ultraviolet light. These free radicals attack the carbon-carbon double bonds (C=C) in the monomers and crosslinking agents, breaking the double bonds and initiating a chain polymerization reaction, thereby transforming the liquid monomer mixture into a solid crosslinked polymer network.

[0050] These specific photoinitiators (such as TPO) have high initiation efficiency and are particularly suitable for deep curing of the systems described in the foregoing embodiments, ensuring that the electrolyte can fully polymerize from the surface to the interior.

[0051] Introducing a photoinitiator is key to achieving "in-situ UV polymerization". It enables the liquid precursor to undergo a rapid phase transition in a short time (e.g., 10-30 minutes) and transform into a solid electrolyte membrane with good mechanical strength.

[0052] It should be noted that although the examples primarily demonstrate the preparation process using trimethylolpropane trimethacrylate (TMPTMA) as a crosslinking agent and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) as a photoinitiator, this is not a limitation of the present invention. Those skilled in the art will understand that other acrylate crosslinking agents containing multiple functional groups (such as polyethylene glycol diacrylate, pentaerythritol triacrylate, etc.) can also construct similar three-dimensional network structures in this system; other photoinitiators capable of generating free radicals in response to ultraviolet light (such as the aforementioned 1173, BPO, etc.) can also initiate this polymerization reaction. Any polymer network with a rigid-flexible structure that can achieve in-situ polymerization and curing of monomers is within the scope of protection of this application.

[0053] This application provides a method for preparing a fluoropolymer solid electrolyte as described in any of the foregoing embodiments, comprising: Step S1: Mix the vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, ethylene carbonate and the crosslinking agent, add the conductive lithium salt and photoinitiator, and stir until the solid substances are completely dissolved.

[0054] This step involves preparing the liquid precursor. Three specific functional monomers (vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, and ethylene carbonate) and a crosslinking agent (such as TMPTMA) are used as a liquid base. Solid components, namely a conductive lithium salt (such as LiTFSI) and a photoinitiator (such as TPO), are then added. Mixing can be achieved through physical stirring. The process continues until all added solids (lithium salt and photoinitiator) are visibly dissolved in the monomer mixture, with no solid particles remaining, resulting in a homogeneous, transparent mixed solution (precursor solution). In this solution, the conductive lithium salt and photoinitiator are molecularly dispersed in the solvent environment composed of monomers and crosslinking agents.

[0055] To ensure that the final solid electrolyte is uniform in microstructure, it is necessary to avoid uneven ion transport or localized weak mechanical properties caused by lithium salt agglomeration. Only when the initiator and monomer are fully miscible can the subsequent photopolymerization reaction be initiated synchronously throughout the system. Only when the lithium salt is completely dissolved can an effective ion conduction channel be provided after the polymer is formed.

[0056] For example, the weighed components can be added to a reaction vessel and stirred using a magnetic stirrer or a mechanical stirrer until the solution is clear and transparent.

[0057] Step S2 involves a polymerization reaction under ultraviolet light to obtain the fluoropolymer solid electrolyte.

[0058] This step is a chemical solidification process, namely a phase transition from a liquid precursor to a solid electrolyte. Specifically, the mixed solution obtained in step one can be irradiated in an ultraviolet (UV) radiation field.

[0059] The reaction mechanism is that the photoinitiator in the solution absorbs ultraviolet light energy and decomposes to generate free radicals. These active free radicals attack the unsaturated double bonds (C=C) in the monomers (vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, ethylene carbonate) and crosslinking agents, thus initiating a free radical polymerization reaction.

[0060] As the reaction proceeds, the free monomer molecules are linked together by covalent bonds to form long chains, and then connected by cross-linking agents to form a three-dimensional network structure, "locking" the dissolved lithium salt in the polymer network.

[0061] Through this step, the liquid mixture is transformed into a solid film-like substance, namely a fluoropolymer solid electrolyte. This product has a specific shape (depending on the container or coating surface) and possesses a certain degree of mechanical strength and elasticity.

[0062] Ultraviolet (UV) photopolymerization is a fast reaction process, typically completing curing within a short time (e.g., 10-30 minutes), making it suitable for industrial production. This method allows the electrolyte to transform from liquid to solid directly on the electrode surface or within the battery casing, filling micropores on the electrode surface and forming excellent solid-solid interface contact, thereby reducing interfacial impedance. Unlike solvent evaporation methods, this method involves direct reaction and curing of the raw materials without solvent removal, avoiding the impact of solvent residue on battery performance.

[0063] In some embodiments, the wavelength of the ultraviolet light is 254 nm or 365 nm.

[0064] The selected photoinitiators (such as TPO) have extremely high absorption efficiency at these specific wavelengths, enabling them to rapidly absorb light energy and decompose to generate high concentrations of active free radicals. This ensures efficient initiation and deep progression of the polymerization reaction. These two wavelengths are the sensitive bands for photoinitiators, ensuring uniform curing of the electrolyte from the surface to the interior, and avoiding low initiation efficiency, incomplete curing, or the formation of unreacted monomer residues due to wavelength mismatch.

[0065] In some embodiments, the polymerization reaction takes 10 to 30 minutes. For example, it can be 10 minutes, 20 minutes, 30 minutes, etc.

[0066] In this embodiment, the mixture is exposed to ultraviolet light of the specific wavelength mentioned above for a duration controlled between 10 and 30 minutes. This allows the liquid precursor solution to undergo complete chemical cross-linking within this time, transforming into a solid film with a stable mechanical structure. This is an optimized time window. Too short a time may result in insufficient monomer conversion and incomplete curing, affecting mechanical strength; too long a time will reduce production efficiency. This range ensures complete conversion of the monomer into a polymer network, while also ensuring that the formed electrolyte possesses good mechanical properties (such as tensile strength) and electrochemical stability.

[0067] In some embodiments, before step S2, the ultraviolet light polymerization reaction is carried out, the mixture is further further described as coating or dripping the mixed material onto the surface of the positive or negative electrode sheet; the ultraviolet light polymerization reaction is carried out in situ on the surface of the positive or negative electrode sheet to form the fluoropolymer solid electrolyte on the surface.

[0068] The liquid material can fully wet the microporous structure of the electrode surface before solidification, and then transforms into a solid in situ. This allows for a close atomic / molecular-level contact between the generated fluoropolymer solid electrolyte and the electrode material.

[0069] This step solves the technical challenge of high interfacial impedance caused by only physical point contact between the traditional solid electrolyte and solid electrode, significantly reducing the battery's interfacial impedance. The generated polymer layer adheres directly to the electrode, eliminating the need for an additional separator; the electrolyte layer itself serves as the separator, simplifying the battery assembly process. This tight interfacial bonding helps improve the battery's cycle stability and rate performance.

[0070] For example, take an appropriate amount (e.g., 60µL) of precursor solution and drop it onto the positive or negative electrode, let it stand for a period of time (e.g., 10 minutes) to allow it to be fully wetted, and then put it directly into the UV curing oven for reaction.

[0071] This application provides a battery comprising a fluoropolymer solid electrolyte as described in any of the foregoing embodiments; or comprising a fluoropolymer solid electrolyte prepared by the preparation method described in the foregoing embodiments.

[0072] The battery provided in this example is an electrochemical energy storage device. Its core feature is the use of the "fluorinated polymer solid electrolyte" described in the aforementioned embodiments as the ion transport medium, replacing the structure of traditional batteries that are completely filled with flammable organic liquids. By using the aforementioned specific fluorinated polymer solid electrolyte, and utilizing its "rigid-flexible" polymer network and fluorinated groups, the battery is endowed with high safety, high ionic conductivity, and excellent mechanical strength.

[0073] Furthermore, the battery also includes a lithium battery electrolyte; the lithium battery electrolyte wets the surface of the fluoropolymer solid electrolyte.

[0074] It should be noted that microwetting usually refers to a liquid electrolyte formed by dissolving a conductive lithium salt in an organic solvent (such as cyclic or linear carbonates). Microwetting refers to the presence of a small amount of liquid electrolyte at the interface between the solid electrolyte and the electrode. This does not mean immersing the battery in a large amount of liquid, but rather refers to a small-scale treatment at the interface (such as adding a small amount of liquid).

[0075] The principle is that in all-solid-state batteries, the contact between the solid electrolyte and the solid electrode is usually a physical point contact with a small contact area, resulting in a large interfacial impedance that hinders ion transport. By introducing a liquid electrolyte to wet the surface, the liquid can fill the microscopic gaps and roughness on the surface of the solid electrolyte and the electrode, transforming the "solid-solid" contact into a "solid-liquid-solid" contact, thereby significantly increasing the effective contact area.

[0076] Micro-wetting effectively opens up ion transport channels, reduces battery internal resistance, and improves the battery's electrochemical performance (such as rate performance and cycle stability). Because only a small amount of liquid electrolyte is used (e.g., below a certain volume), the battery will not continue to burn in extreme conditions such as when exposed to open flames. This allows the battery to achieve the low impedance advantages of liquid electrolytes while maintaining the high safety of solid-state batteries.

[0077] Furthermore, the battery is a lithium metal battery; the negative electrode of the battery includes metallic lithium.

[0078] The aforementioned lithium metal has an extremely high theoretical specific capacity (3860 mAh g). -1 ), far exceeding that of traditional graphite anodes (372mAh g), -1 It is an ideal anode material for building high-energy-density batteries.

[0079] The fluoropolymer solid electrolyte contains a rigid benzene ring structure, which has high mechanical strength and can physically block and inhibit the growth of lithium dendrites on the lithium metal surface, preventing dendrites from piercing the electrolyte and causing short circuits. The fluorinated groups (such as -CF3) in the fluoropolymer have strong reducing activity, which is beneficial for forming a stable solid electrolyte interphase (SEI) film (rich in LiF and other components) on the lithium anode surface during cycling, thereby promoting uniform lithium ion deposition and reducing the formation of dead lithium.

[0080] By combining a lithium metal anode and a fluoropolymer solid electrolyte, this battery achieves both high energy density and long cycle life. The specific polymer structure addresses two major pain points common in lithium metal batteries: lithium dendrite growth and safety hazards, allowing it to maintain a high capacity retention rate even after multiple charge-discharge cycles. This solid electrolyte layer not only conducts lithium ions within the battery but also, thanks to its excellent mechanical strength, acts as a separator, effectively isolating the positive and negative electrodes and preventing short circuits.

[0081] This application provides an electrical device, including a battery as described in the foregoing embodiments.

[0082] The aforementioned electrical equipment includes the lithium battery described above, thereby utilizing the high safety, excellent electrochemical performance, and long cycle life provided by the battery as a power source or energy storage component. According to the definition in this application, the scope of such electrical equipment is very broad, including devices with the lithium battery internally installed, devices that are powered by the lithium battery even if it is not mounted on the device itself, or facilities that utilize the lithium battery for energy storage. Specifically, electrical equipment may include, but is not limited to, the following types: transportation vehicles (such as electric vehicles and electric bicycles), portable electronic devices and accessories (such as mobile phones, tablets, smartwatches, and power banks), and large-scale energy storage systems (such as energy storage battery packs and energy storage power stations).

[0083] The present invention will be further illustrated below with specific embodiments. However, it should be understood that these embodiments are merely for the purpose of more detailed illustration and should not be construed as limiting the present invention in any way.

[0084] Example 1 This embodiment describes the preparation of a fluoropolymer solid electrolyte.

[0085] Experimental methods: Preparation of fluoropolymer solid electrolytes: Vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, and ethylene carbonate monomers were mixed in a mass ratio of 4:5:1. Then, 1% of trimethylolpropane trimethacrylate crosslinking agent, 30% LiTFSI, and 0.2% TPO photoinitiator were added. The mixture was stirred until the solids were completely dissolved. After polymerization under ultraviolet light at a wavelength of 365 nm for 30 min, a fluoropolymer solid electrolyte was obtained.

[0086] A schematic diagram of the reaction of fluoropolymers is shown below. Figure 1 As shown.

[0087] Example 2 This embodiment describes the preparation of a fluoropolymer solid electrolyte.

[0088] Experimental methods: Preparation of fluoropolymer solid electrolytes: The preparation of the fluorinated solid polymer solid electrolyte in this embodiment differs from that in Example 1 in that the mass ratio of vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, and ethylene ethylene carbonate is 4:4:2, while other conditions and parameters are the same as in Example 1.

[0089] Example 3 This embodiment describes the preparation of a fluoropolymer solid electrolyte.

[0090] Experimental methods: Preparation of fluoropolymer solid electrolytes: The preparation of the fluorinated solid polymer solid electrolyte in this embodiment differs from that in Example 1 in that the mass ratio of vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, and ethylene ethylene carbonate is 4:3:3, while other conditions and parameters are the same as in Example 1.

[0091] Example 4 This embodiment describes the preparation of a fluoropolymer solid electrolyte.

[0092] Experimental methods: Preparation of fluoropolymer solid electrolytes: The preparation of the fluorinated solid polymer solid electrolyte in this embodiment differs from that in Example 1 in that the mass ratio of vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, and ethylene carbonate is 4:2:4, while other conditions and parameters are the same as in Example 1. The infrared spectrum of the final product obtained in Example 4 is as follows: Figure 2 As shown, optical images are as follows Figure 3 As shown in the image, infrared spectroscopy analysis revealed the disappearance of C=C bond signals in the fluoropolymer solid electrolyte, indicating that the copolymer was formed by breaking unsaturated C=C bonds in each monomer. Optical images also indicate that the prepared fluoropolymer solid electrolyte possesses good elasticity and deformation capacity.

[0093] Example 5 This embodiment describes the preparation of a fluoropolymer solid electrolyte.

[0094] Experimental methods: Preparation of fluoropolymer solid electrolytes: The preparation of the fluorinated solid polymer solid electrolyte in this embodiment differs from that in Example 1 in that the mass ratio of vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, and ethylene carbonate is 4:1:5, while other conditions and parameters are the same as in Example 1.

[0095] Example 6 This embodiment describes the preparation of a fluoropolymer solid electrolyte.

[0096] Experimental methods: Preparation of fluorinated polymer solid electrolyte: The preparation of the fluorinated solid polymer solid electrolyte in this embodiment differs from that in Example 1 in that the mass ratio of vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, and ethylene carbonate is 1:2:4 (i.e., VTMS is taken as the lower limit, and the other two components are fixed according to the preferred ratio of Example 4), while other conditions and parameters are the same as in Example 1.

[0097] Example 7 This embodiment describes the preparation of a fluoropolymer solid electrolyte.

[0098] Experimental methods: Preparation of fluoropolymer solid electrolyte: The preparation of the fluoropolymer solid electrolyte in this example differs from that in Example 1 in that the mass ratio of vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, and ethylene carbonate is 8:2:4 (i.e., VTMS is taken as the upper limit), while other conditions and parameters are the same as in Example 1.

[0099] Comparative Example 1 This comparative example demonstrates the preparation of a solid electrolyte.

[0100] Experimental methods: Preparation of non-fluorinated polymer solid electrolytes: Vinyltris(2-methoxyethoxy)silane and ethylene ethylene carbonate monomers were mixed in a mass ratio of 1:1. Then, 1% of trimethylolpropane trimethacrylate crosslinking agent, 30% of LiTFSI and 0.2% of TPO photoinitiator were added. The mixture was stirred until the solid matter was completely dissolved. After polymerization under ultraviolet light at a wavelength of 365 nm for 30 min, a fluoropolymer solid electrolyte was obtained.

[0101] Comparative Example 2 This comparative example demonstrates the preparation of a solid electrolyte without flexible siloxane chains.

[0102] Experimental methods: Trifluoromethylstyrene and ethylene carbonate monomers were mixed at a mass ratio of 1:1 (without adding vinyltris(2-methoxyethoxy)silane). Then, 1% (by mass) of trimethylolpropane trimethacrylate crosslinking agent, 30% LiTFSI, and 0.2% TPO photoinitiator were added. The mixture was stirred until the solids were completely dissolved, and polymerized under 365 nm UV light for 30 min. Results: The prepared polymer film was hard and brittle, easily breaking upon peeling from the mold. It could not form a complete self-supporting film for subsequent battery assembly and testing, indicating that polymers lacking flexible siloxane segments cannot meet the mechanical flexibility requirements of solid-state electrolytes.

[0103] Test experiment: 1. Testing method: Using the solid electrolytes prepared in the examples and comparative examples, the following batteries were assembled: (1) Preparation of positive electrode sheet: LiCoO2 (LCO), polyvinylidene fluoride binder (PVdF) and conductive agent acetylene black are dissolved in an appropriate amount of N-methylpyrrolidone (NMP) in a mass ratio of 8:1:1. After stirring evenly, the slurry is cast onto aluminum foil and dried in a vacuum oven at 120 °C for 12 h. Then, it is cut into 12 mm electrode sheets for later use.

[0104] (2) The battery assembly process employs an in-situ polymerization method, and the lithium battery electrolyte described above is dropped onto the surface of the solid electrolyte (provided in the examples and comparative examples) for micro-wetting. A combustion test is then performed on the micro-wetted electrolyte, and the results are as follows: Figure 4As shown, the fluoropolymer solid electrolyte used was the fluoropolymer solid electrolyte prepared in Example 4, which was UV-polymerized on the battery casing. The diameter of the battery casing was 20 mm. The volume of lithium battery electrolyte added was calculated based on the area of ​​the fluoropolymer solid electrolyte. Less than 14 μL of cm⁻¹ was added. -1 When the electrolyte does not shrink or deform significantly, and it never burns, it exhibits good safety performance.

[0105] Furthermore, comparative experimental results also revealed the core role of the "fluorinated polymer solid electrolyte" in the system. If only liquid electrolyte is used (without a solid polymer framework), the battery is highly susceptible to leakage and combustion during safety tests; while using only traditional solid electrolytes (without fluorinated groups / flexible chains), the excessive interfacial impedance leads to cycling failure. The fluorinated polymer solid electrolyte of this application not only provides a high-mechanical-strength physical framework to block dendrites and prevent short circuits (e.g., Figure 7 As shown in the tensile test), it also utilizes the special properties of its fluorine-containing groups to provide intrinsic ion conductivity. Microwetting is merely an auxiliary means of improving physical contact using a very small amount of liquid; the high safety of the battery (such as...) Figure 4 (as shown in the combustion test) and dendrite resistance (such as...) Figure 19 (As shown in the SEM image) This is mainly due to the solid electrolyte itself. Therefore, this fluoropolymer solid electrolyte is the key material basis for achieving the overall performance of the battery.

[0106] Assembly of SS||SS symmetric cells: 60 µL of precursor solution (containing monomer, crosslinking agent, lithium salt, and photoinitiator) was dropped onto the surface of a stainless steel sheet. After thorough wetting for 10 min, the solution was reacted under 365 nm UV light for 30 min to obtain an in-situ polymerized fluoropolymer solid electrolyte (SPE). 2 µL of cm⁻¹ was then dropped onto the SPE. -1 The lithium battery electrolyte, when encapsulated with another stainless steel sheet, yields a button cell, i.e., an SS||SS symmetric cell. The encapsulated SS||SS symmetric cell is then subjected to electrochemical impedance spectroscopy to obtain the bulk resistance R of the electrolyte, according to the formula: ; The ionic conductivity (σ) of the solid polymer electrolyte can be calculated. l is the film thickness of the polymer electrolyte, and S is the contact area between the steel electrode and the electrolyte.

[0107] The change in electrolyte ionic conductivity at different temperatures, when conforming to the Arrhenius equation, allows the calculation of the activation energy Ea using the following formula: ; T is the thermodynamic temperature, A is the pre-exponential factor, and k is the Boltzmann constant (1.38 × 10⁻⁶). -23 JK -1 ).

[0108] 2. Test Results and Analysis: First, the prepared electrolyte was structurally characterized. Figure 2 Infrared spectroscopy showed that the characteristic C=C double bond absorption peak in the monomer completely disappeared after polymerization, confirming that the monomer underwent complete polymerization under the action of ultraviolet light and photoinitiator, leaving no residual liquid monomer. This complete solidification contributes to the good mechanical strength of the electrolyte (e.g., Figure 7 (as shown) and the premise of chemical stability.

[0109] The test results of ionic conductivity are as follows: Figure 5 , Figure 6 As shown, the change in the proportion of fluoropolymer monomers has a significant impact on ionic conductivity. Compared with Comparative Example 1, Example 4 has higher ionic conductivity and lower activation energy.

[0110] Furthermore, a comparison of Example 6 (low VTMS content), Example 7 (high VTMS content), and Example 4 reveals that the ionic conductivity of the electrolyte increases with increasing vinyltris(2-methoxyethoxy)silane (VTMS) content. Although Example 6 has a low VTMS content, it still maintains acceptable ionic conductivity, demonstrating the effectiveness of the formulation over a wide range. Example 7 exhibits the highest ionic conductivity because the flexible siloxane segments introduced by VTMS have strong mobility, effectively promoting lithium-ion transport.

[0111] Figure 7 These are the tensile test results of the fluoropolymer solid electrolytes prepared in Example 4 and Comparative Example 1. Example 4 exhibits stronger tensile strength.

[0112] In terms of mechanical properties, Comparative Example 2 (without VTMS) was extremely brittle after film formation due to the lack of flexible segments, and could not withstand tensile tests, confirming the necessity of vinyltris(2-methoxyethoxy)silane for constructing a network that combines rigidity and flexibility and imparting toughness to the electrolyte. Comparing Examples 6 and 7, Example 6 exhibited a higher Young's modulus (harder), while Example 7 exhibited excellent ductility (softer). This indicates that by adjusting the proportion of VTMS in the range of (1~8), a performance balance can be achieved between "high mechanical strength" and "high ionic conductivity / high elasticity" according to actual needs, and this proportion range has reasonable technical support.

[0113] Assembly of Li||Li symmetric cells: 60 µL of precursor solution (containing monomer, crosslinking agent, lithium salt, and photoinitiator) was dropped onto the surface of a lithium sheet. After thorough wetting for 10 min, the solution was reacted under 365 nm UV light for 30 min to obtain an in-situ polymerized fluoropolymer solid electrolyte (SPE). 2 µL of cm⁻¹ was then dropped onto the SPE. -1 The lithium battery electrolyte is then encapsulated with another lithium chip to obtain a button cell, i.e., a Li||Li symmetric cell. Figure 8 , Figure 9 , Figure 10 , Figure 11 The lithium-ion transference number, Tafel curve, and lithium plating / delithiation test results were obtained using Li||Li symmetric cells. The fluorinated polymer solid electrolyte used was the same as that prepared in Example 4 and Comparative Example 1. The battery assembled in Example 4 exhibited a high lithium-ion transference number of 0.68 and a lithium plating / delithiation result of 2 mA cm⁻¹. -2 The high exchange current density is beneficial for reducing the Li-ion exchange rate at the electrode-solid electrolyte interface during charging and discharging. + The concentration gradient slows down lithium dendrite growth and enhances lithium ion migration rate, resulting in good cycle stability and long cycle time for the Li||Li symmetric battery in the plating / delithiation test.

[0114] Assembly of Li / SS half-cells: 60 µL of precursor solution (containing monomer, crosslinking agent, lithium salt, and photoinitiator) was dropped onto the surface of a lithium sheet. After thorough wetting for 10 min, the solution was reacted under 365 nm UV light for 30 min to obtain an in-situ polymerized fluoropolymer solid electrolyte (SPE). 2 µL of cm⁻¹ was then dropped onto the SPE. -1 The lithium battery electrolyte is then encapsulated with another stainless steel sheet to obtain a button cell, i.e., a Li / SS half cell. Figure 12 The LSV test of the Li / SS half cell was conducted using the fluorinated polymer solid electrolyte prepared in Example 4 and Comparative Example 1. It can be seen that the battery assembled in Example 4 has a higher oxidation voltage, while the battery in Comparative Example 1 begins to decompose at around 4.5 V. The high oxidation potential of Example 4 endows the lithium battery or electrical equipment with good high-voltage cycling capability.

[0115] To further explore the underlying mechanism of the excellent electrochemical stability of fluoropolymer solid electrolytes, this application analyzed the orbital energy levels and binding energy of the molecules using DFT theoretical calculations.

[0116] like Figure 13The diagram shows the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of monomers and polymers. Calculations show that fluoropolymers (PVTV) have lower HOMO and LUMO energy levels compared to non-fluoropolymers (PVV). Lower HOMO energy levels mean that the polymer is less likely to lose electrons, indicating that fluoropolymers have stronger antioxidant capabilities, which theoretically explains... Figure 12 Example 4 exhibits a high oxidation decomposition potential. Simultaneously, the lower LUMO energy level indicates more active reducing properties, which is beneficial for preferential reduction on the negative electrode side to form a stable SEI film, thereby promoting uniform lithium deposition.

[0117] like Figure 14 The diagram illustrates the binding energies of different molecules to lithium ions. The binding energy of the fluoropolymer (PVTV) to lithium ions (-0.32 eV) differs compared to the non-fluorinated system, primarily due to the introduction of the p-trifluoromethylstyrene monomer (TF3). The trifluoromethyl group (-CF3) in TF3 exhibits a strong electron-withdrawing effect, effectively weakening the binding energy of lithium ions (Li) in the lithium salt (LiTFSI). + ) and anion (TFSI) - The electrostatic forces between the free lithium ions and the lithium salt promote the dissociation of the lithium salt. This mechanism not only increases the concentration of free lithium ions in the system, improves ionic conductivity and lithium ion transference number, but also effectively improves the stability of the interface.

[0118] Figure 15 , Figure 16 These are the HOMO and LUMO diagrams of the molecule and the binding energy diagram of the molecule with lithium ions, obtained from DFT theoretical calculations. It can be seen that the fluoropolymer (PVTV) has lower HOMO and LUMO energy levels than the non-fluoropolymer (PVV), indicating that the fluoropolymer has stronger antioxidant capacity and more active reducing properties, corresponding to the high oxidation potential in Example 4. Simultaneously, the stronger reducing properties are beneficial for the formation of an SEI film on the negative electrode side, promoting uniform lithium deposition. The lower binding energy of the fluoropolymer with lithium ions can be attributed to the strong electron-withdrawing effect of the introduced p-trifluoromethylstyrene monomer and the -CF3 group, which weakens the Li in LiTFSI. + With TFSI - The force promotes the dissociation of lithium salts, which can improve the electrochemical stability of polymer electrolytes, enhance lithium-ion transport efficiency, improve interface stability, and improve battery safety.

[0119] Assembly of LCO / Li half-cells: 60 µL of precursor solution (containing monomer, crosslinking agent, lithium salt, and photoinitiator) was dropped onto the lithium sheet surface. After thorough wetting for 10 min, the solution was reacted under 365 nm UV light for 30 min to obtain an in-situ polymerized fluoropolymer solid electrolyte (SPE). 2 µL of cm⁻¹ was then dropped onto the SPE. -1 The lithium battery electrolyte is added to the positive electrode and then encapsulated to obtain a button cell, i.e., an LCO / Li half cell.

[0120] Figure 15 , Figure 16 , Figure 17 , Figure 18 The cycling graphs, charge-discharge curves at specific cycles, and rate performance graphs of the LCO / Li half-cells in Example 4 and Comparative Example 1 show that the lithium battery assembled in Example 4 retains 85.4% of its capacity after 300 cycles, while the lithium battery assembled in Comparative Example 1 retains only 30.2% of its capacity after 150 cycles. A clear capacity decrease trend is visible in the charge-discharge curve of the lithium battery assembled in Comparative Example 1, although the decrease is more gradual in Example 4. The lithium battery assembled in Example 4 also exhibits good rate performance. In contrast, the high-rate performance of Comparative Example 1 is poor, with a significant capacity decrease when the current density recovers from 2C to 0.1C, indicating poor reversibility of the lithium battery.

[0121] Figure 19 , Figure 20 , Figure 21 , Figure 22 The images show SEM, TEM, and XPS characterizations of the negative electrode, electrolyte, and positive electrode after cycling. It can be seen that the lithium negative electrode of the battery assembled in Example 4 is relatively compact after cycling, the surface of the fluoropolymer solid electrolyte remains almost unchanged before and after cycling, and the CEI film formed on the LCO positive electrode surface is relatively uniform. In contrast, the battery assembled in Comparative Example 1 has a loose lithium negative electrode with many cracks, significant cracking of the solid polymer electrolyte after cycling, and an uneven film formation on the LCO positive electrode surface. The XPS test results of the positive electrode also show that the CEI film formed on the LCO positive electrode surface of the battery assembled in Example 4 after cycling contains abundant LiF, which is beneficial for improving the cycle stability of the lithium battery.

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fluoropolymer solid electrolyte, characterized in that, The fluoropolymer solid electrolyte comprises a fluoropolymer and a conductive lithium salt; The fluoropolymer is polymerized from raw materials including vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, ethylene carbonate, and a crosslinking agent.

2. The fluoropolymer solid electrolyte as described in claim 1, characterized in that, The conductive lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium difluorooxalate borate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, and lithium bis(trifluoromethanesulfonyl)imide.

3. The fluoropolymer solid electrolyte as described in claim 1, characterized in that, The crosslinking agent includes trimethylolpropane trimethacrylate.

4. The fluoropolymer solid electrolyte as described in claim 1, characterized in that, The mass ratio of vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, and ethylene carbonate is (1~8):(1~6):(1~6).

5. The fluoropolymer solid electrolyte as described in claim 1, characterized in that, Based on the total mass of the monomers, the mass of the conductive lithium salt is 10% to 50%; and / or, the mass of the crosslinking agent is 0.5% to 2%.

6. The fluoropolymer solid electrolyte as described in claim 1, characterized in that, The raw materials also include photoinitiators; Preferably, the photoinitiator comprises one or more of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2-hydroxy-2-methyl-1-phenylpropanone, and benzoyl peroxide; Preferably, the mass of the photoinitiator is 0.1% to 1% based on the total mass of the monomers.

7. A method for preparing a fluoropolymer solid electrolyte as described in any one of claims 1-6, characterized in that, include: The vinyltris(2-methoxyethoxy)silane, p-trifluoromethylstyrene, ethylene carbonate and the crosslinking agent are mixed, and the conductive lithium salt and photoinitiator are added. The mixture is stirred until the solids are completely dissolved. The polymerization reaction was carried out under ultraviolet light to obtain the fluoropolymer solid electrolyte.

8. The method for preparing the fluoropolymer solid electrolyte as described in claim 7, characterized in that, The wavelength of the ultraviolet light is 254 nm or 365 nm; and / or, The polymerization reaction takes 10 to 30 minutes; and / or, Before the ultraviolet light polymerization reaction, the method further includes: coating or dripping the mixed material onto the surface of the positive or negative electrode sheet; the ultraviolet light polymerization reaction is carried out in situ on the surface of the positive or negative electrode sheet to form the fluorinated polymer solid electrolyte on the surface.

9. A battery, characterized in that, Includes the fluoropolymer solid electrolyte as described in any one of claims 1-6; or includes the fluoropolymer solid electrolyte prepared by the preparation method described in claim 7 or 8; Preferably, the battery further includes a lithium battery electrolyte; the lithium battery electrolyte wets the surface of the fluoropolymer solid electrolyte; Preferably, the battery is a lithium metal battery; the negative electrode of the battery comprises metallic lithium.

10. An electrical-related device, characterized in that, Includes the battery as described in claim 9.

Images