MOF (Metal Organic Framework)-loaded PET (Polyethylene Terephthalate)-based diaphragm composite ether-cyano high-voltage electrolyte type gel electrolyte as well as preparation method and application thereof

Abstract

The invention discloses an MOF (Metal Organic Framework)-loaded PET (Polyethylene Terephthalate)-based diaphragm composite ether-cyano high-voltage electrolyte type gel electrolyte as well as a preparation method and application thereof, and the MOF-loaded PET-based diaphragm composite ether-cyano high-voltage electrolyte type gel electrolyte comprises an MOF-loaded PET-based diaphragm and ether-cyano high-voltage electrolyte gel positioned on the MOF-loaded PET-based diaphragm, the ether-cyano group high-voltage electrolyte gel is formed by pouring an ether-cyano group high-voltage electrolyte gel precursor solution on the MOF-loaded PET-based diaphragm, and the ether-cyano group high-voltage electrolyte gel precursor solution comprises a polymer, an ether-cyano group difunctional high-voltage electrolyte, a lithium salt and a solvent. The composite system has both high ionic conductivity and high lithium ion transference number, remarkably improved oxidative decomposition resistance and high Young modulus, can effectively inhibit lithium dendrite puncture, and synergistically realizes stable circulation under the condition of 4.6 V (vs. Li < + > / Li) high voltage.

Description

Technical Field

[0001] This invention belongs to the field of gel polymer electrolyte technology, specifically relating to a MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries, due to their high energy density, long cycle life, and low self-discharge rate, have become the preferred power technology for portable electronic devices, electric vehicles, and energy storage systems. However, the theoretical specific capacity of traditional graphite anodes is limited (approximately 372 mAh / g), making it difficult to meet the ever-increasing demand for high energy density. Lithium metal anodes, with their extremely high theoretical specific capacity (3860 mAh / g) and the lowest reduction potential (-3.04 V vs. standard hydrogen electrode), are considered ideal anode materials for next-generation high-energy-density batteries. High-capacity cathode materials, such as nickel-rich layered oxides (LiNi), are also suitable for this purpose. 0.8 Co 0.1 Mn 0.1 O2 (NCM811) can further improve the energy density of the battery. Nevertheless, this system still faces two major challenges: First, lithium metal anodes are prone to forming lithium dendrites during deposition / stripping. If the electrolyte's mechanical strength is insufficient, the dendrites may puncture the battery, causing an internal short circuit. Second, traditional carbonate-based electrolytes, under high voltages (>4.3 V vs. Li),... + Li₂O₃ is prone to oxidation and decomposition, leading to poor interface stability, rapid capacity decay, and battery failure. To improve the mechanical strength of the electrolyte, a separator is often introduced as a supporting framework.

[0003] PET nonwoven fabric (polyethylene terephthalate, PET) possesses good thermal stability and is a potential separator material. However, PET nonwoven fabric has a large intrinsic pore size and high porosity. To ensure sufficient mechanical strength to resist dendrite penetration, its thickness often needs to be increased, which affects the volumetric energy density of the battery. One feasible approach is to improve the overall performance of PET nonwoven fabric-based polymer electrolytes by introducing newly developed oxidation-resistant solvents or functional additives into the electrolyte, especially high-voltage electrolytes. However, while commonly used ether solvents have excellent lithium-ion transport capabilities, their oxidation resistance is typically below 4.0 V, making them difficult to match with high-voltage cathodes. The strong electron-attracting ability of the cyano (-C≡N) functional group can effectively suppress the loss of lone pair electrons in ether oxygen, thereby improving oxidation stability; however, it affects compatibility with the anode, the overall ionic conductivity of the electrolyte, and the lithium-ion transference number. Previous research results (202411831326.9 "Preparation Method and Application of PET-Reinforced Double-Crosslinked Polyionic Liquid Composite Solid Electrolyte") show that by simultaneously improving the composition of both PET nonwoven fabric and polymer electrolyte, it is possible to prepare PET nonwoven fabric-based solid polymer electrolyte films with thinner thickness, higher mechanical strength, higher porosity, better ionic conductivity, and a higher electrochemical stability window. However, this process relies on the modification of composite PET fiber nonwoven fabric with nano-zinc oxide and the use of functionalized alkenyl ionic liquid as the main electrolyte precursor. The chemical bonding between the nonwoven fabric and the ionic liquid is achieved by thermal polymerization, followed by the self-crosslinking of the ionic liquid through photopolymerization. The performance of the product is limited by the selection of raw materials and the stepwise crosslinking polymerization. Moreover, the obtained PET nonwoven fabric-based solid polymer electrolyte film still fails to achieve a balance between high ionic conductivity and high lithium-ion transference number.

[0004] Developing a composite gel electrolyte system that can simultaneously suppress lithium dendrite growth, withstand high-voltage oxidation, possess excellent interface stability, and balance high ionic conductivity and high lithium-ion transference number is of great significance for advancing the development of high-energy-density lithium metal batteries. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte, its preparation method, and its application. This electrolyte constructs a reinforced membrane framework by loading MOF materials onto a PET nonwoven fabric matrix and introducing an ether-cyano bifunctional high-voltage electrolyte, ultimately forming an integrated gel system with a multi-level structure. This system combines the ion sieving effect and anion anchoring effect of the regular pores of MOF with the high oxidation stability of the ether-cyano bifunctional high-voltage electrolyte, exhibiting a balance of high ionic conductivity and high lithium-ion transference number, significantly improved antioxidant capacity, and high Young's modulus. It can effectively suppress lithium dendrite penetration, synergistically achieving a corresponding battery operating at 4.6 V (vs. Li). + Stable cycling under high voltage conditions ( / Li).

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] On one hand, a MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte is provided, comprising a MOF-loaded PET-based membrane and an ether-cyano high-voltage electrolyte gel located on the MOF-loaded PET-based membrane; the ether-cyano high-voltage electrolyte gel is formed by casting an ether-cyano high-voltage electrolyte gel precursor solution onto the MOF-loaded PET-based membrane, the ether-cyano high-voltage electrolyte gel precursor solution comprising a polymer, an ether-cyano bifunctional high-voltage electrolyte, a lithium salt, and a solvent.

[0008] Furthermore, a method for preparing the above-mentioned MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte is provided, comprising:

[0009] Provide PET-based separators with MOF loading;

[0010] The polymer, ether-cyano bifunctional high-voltage electrolyte, and lithium salt were dissolved together in an organic solvent to obtain a homogeneous and transparent ether-cyano high-voltage electrolyte gel precursor solution.

[0011] The MOF-loaded PET-based separator is placed in a polytetrafluoroethylene mold, and the ether-cyano high-voltage electrolyte gel precursor solution is poured onto the MOF-loaded PET-based separator. After vacuum drying, the MOF-loaded PET-based separator composite ether-cyano high-voltage electrolyte gel electrolyte is obtained.

[0012] On the other hand, a lithium-ion battery is provided, comprising the above-mentioned MOF-loaded PET-based separator composite ether-cyano high-voltage electrolyte gel electrolyte.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] 1) The present invention relates to a MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte. By introducing an ether-cyano bifunctional high-voltage electrolyte into the MOF-loaded PET-based membrane, the oxidation stability of the resulting system is significantly improved. While maintaining high ionic conductivity and high lithium-ion transference number, it can achieve oxidation stability at 4.6V (vs. Li). + It operates stably within a voltage window of / Li and above, thus being well compatible with high-capacity nickel-rich layered cathode materials (such as NCM811), providing a key material basis for constructing high-voltage, high-energy-density lithium metal batteries.

[0015] 2) The invention constructs an integrated composite gel electrolyte system that highly integrates the membrane, polymer matrix, functional electrolyte and lithium salt. This system combines the good interfacial properties of gel electrolyte, the high safety of solid electrolyte and the high ion conductivity of liquid electrolyte, overcomes the inherent defects of single-component materials, and exhibits excellent comprehensive electrochemical performance and safety performance, and has important practical application value.

[0016] 3) The MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte of the present invention is preferably prepared by in-situ growth of the MOF-loaded PET-based membrane. The process route of hydrolysis with hydrochloric acid solution-surface pretreatment with aminosilane coupling agent-metal ion pre-fixation-liquid phase in-situ growth can achieve uniform, dense and firm growth of MOF on the relatively inert PET nonwoven fabric surface. It can effectively avoid the defects of poor bonding between MOF and matrix, MOF agglomeration and difficulty in maintaining the original macroscopic morphology of PET caused by physical blending and other methods. It provides a supporting foundation for subsequent casting of ether-cyano high-voltage electrolyte gel precursor liquid and ensures the structural integrity of long-term cycling.

[0017] 4) The in-situ MOF growth method of the present invention has mild process conditions, is easy to operate, and has good adjustability and scalability.

[0018] 5) The MOF-loaded PET-based separator of this invention constructs a robust composite separator structure of flexible polymer fibers and rigid inorganic materials by loading MOFs onto the surface of PET nonwoven fabric fibers. This structure solves the problem of insufficient mechanical strength caused by the large intrinsic pore size and high porosity of PET nonwoven fabric, significantly improving the Young's modulus and mechanical strength of the separator, effectively resisting the growth and puncture of lithium dendrites during cycling, and improving battery safety.

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1Scanning electron microscope images of (a) the original PET nonwoven fabric and (b) the PET@MOF membrane prepared in Example 1;

[0021] Figure 2 Atomic force microscopy Young's modulus distribution of (a) the original PET nonwoven fabric and (b) the PET@MOFT membrane prepared in Example 1;

[0022] Figure 3 The AC impedance spectra of the membrane composite gel electrolytes prepared in Example 1, Comparative Example 1, and Comparative Example 2 are shown.

[0023] Figure 4 The apparent activation energy curves of the membrane composite gel electrolytes prepared in Example 1, Comparative Example 1, and Comparative Example 2 are shown.

[0024] Figure 5 The graph shows the lithium-ion transference number test results of the membrane composite gel electrolytes prepared in (a) Example 1, (b) Comparative Example 1 and (c) Comparative Example 2;

[0025] Figure 6 The limiting current density test curves of the membrane composite gel electrolytes prepared in (a) Example 1, (b) Comparative Example 1 and (c) Comparative Example 2 based on lithium symmetric batteries are shown.

[0026] Figure 7 Linear sweep voltammetry curves of the membrane composite gel electrolytes prepared in Example 1, Comparative Example 1, and Comparative Example 2;

[0027] Figure 8 This is a schematic diagram of the rate performance of NCM811 full cells using the membrane composite gel electrolytes prepared in Example 1, Comparative Example 1, and Comparative Example 2.

[0028] Figure 9 This is a schematic diagram of the cycling performance of NCM811 full cells with membrane composite gel electrolytes prepared using Example 1, Comparative Example 1, and Comparative Example 2.

[0029] Figure 10 The voltage-time curve of the NCM811 full cell using the membrane composite gel electrolyte prepared in Comparative Example 1 during the first cycle;

[0030] Figure 11 The AC impedance spectrum of the membrane composite gel electrolyte prepared in Example 2;

[0031] Figure 12 The linear sweep voltammetry curve of the membrane composite gel electrolyte prepared in Example 2;

[0032] Figure 13 The AC impedance spectrum of the membrane composite gel electrolyte prepared in Example 3;

[0033] Figure 14 The linear sweep voltammetry curve of the membrane composite gel electrolyte prepared in Example 3;

[0034] Figure 15 The AC impedance spectrum of the membrane composite gel electrolyte prepared in Example 4;

[0035] Figure 16 The linear sweep voltammetry curve is shown for the diaphragm composite gel electrolyte prepared in Example 4. Detailed Implementation

[0036] The technical solution will now be clearly and completely described with reference to the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0037] In the following description, the term "and / or" is used to describe the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist simultaneously. A and B can be singular or plural.

[0038] In the following description, the terms “including,” “containing,” “having,” and “containing” are open-ended terms, meaning that they include but are not limited to.

[0039] Those skilled in the art should understand that, in the following description of the embodiments of this application, the sequence of numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0040] Those skilled in the art will understand that the numerical ranges in the embodiments of this application should be understood to specifically disclose each intermediate value between the upper and lower limits of the range. Each smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this application. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0041] Unless otherwise stated, the technical / scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. While this application describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this application. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0042] The technical principle employed in this invention is as follows: This invention is based on the chemical modification of the diaphragm and the physical curing of an electrolyte gel precursor solution on the modified diaphragm to form a PET-based diaphragm composite ether-cyano high-voltage electrolyte gel electrolyte with MOF loading. The chemical modification of the diaphragm is based on the acidic hydrolysis of PET nonwoven fabric and the in-situ growth of MOF after grafting aminosilane coupling agent. The acidic hydrolysis of PET involves hydrolyzing the polyester chains in PET under acidic conditions, generating functional groups carboxyl and hydroxyl groups on the surface of the PET nonwoven fabric fibers.

[0043]

[0044] Grafted aminosilane coupling agents (taking APTES as an example) consist of: First, APTES undergoes hydrolysis in the presence of trace amounts of moisture, generating highly reactive silanol groups:

[0045]

[0046] Subsequently, the hydrolyzed APTES reacts with the functional groups on the surface of the hydrolyzed PET through various pathways: including the condensation reaction of silanol groups with surface hydroxyl groups, the reaction of amino groups with surface carboxyl groups to form amide bonds, the reaction of amino groups with surface ester groups to form amide bonds, and the formation of a cross-linked siloxane network composed of siloxane bonds (Si–O–Si) between adjacent silanol groups on the PET surface through condensation, as detailed below:

[0047] Reaction 1: The silanol groups undergo a condensation reaction with the surface hydroxyl groups, grafting the amino group onto the PET:

[0048] Reaction 2: The amino groups in APTES react with the carboxyl groups on the PET surface to form amide bonds:

[0049]

[0050] Reaction 3: The amino groups in APTES react with the ester groups on the PET surface to form amide bonds.

[0051]

[0052] Reaction 4: A condensation reaction occurs between adjacent silanol groups, forming a cross-linked siloxane network composed of siloxane bonds (Si–O–Si) on the PET surface.

[0053] After grafting aminosilane coupling agent, PET nonwoven fabric is sequentially mixed with metal ion solution and organic ligand solution to grow MOF in situ on its surface, resulting in a PET-based separator loaded with MOF. Ether-cyano high-voltage electrolyte gel precursor solution is poured onto the PET-based separator loaded with MOF and physically cured to obtain a separator composite gel electrolyte system. The separator and electrolyte are optimized simultaneously, synergistically achieving a balance between inhibiting lithium dendrite growth, resisting high-voltage oxidation, optimizing interface stability, and high ionic conductivity and high lithium ion transference number.

[0054] On one hand, a MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte is provided, comprising a MOF-loaded PET-based membrane and an ether-cyano high-voltage electrolyte gel located on the MOF-loaded PET-based membrane; the ether-cyano high-voltage electrolyte gel is formed by casting an ether-cyano high-voltage electrolyte gel precursor solution onto the MOF-loaded PET-based membrane, the ether-cyano high-voltage electrolyte gel precursor solution comprising a polymer, an ether-cyano bifunctional high-voltage electrolyte, a lithium salt, and a solvent.

[0055] This invention provides a MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte, comprising a MOF-loaded PET-based membrane and an ether-cyano high-voltage electrolyte gel located on the MOF-loaded PET-based membrane. The ether-cyano high-voltage electrolyte gel is formed by casting an ether-cyano high-voltage electrolyte gel precursor solution onto the MOF-loaded PET-based membrane and then physically curing it. This invention effectively combines the ion sieving effect and anion anchoring function of the regular pores of MOF with the high oxidation stability of the ether-cyano molecular bifunctional high-voltage electrolyte, achieving a high-voltage electrolyte at 4.6 V (vs. Li). + A membrane composite electrolyte that cycles stably under high voltage conditions (Li).

[0056] The method for obtaining the above-mentioned ether-cyano high-pressure electrolyte gel is to cast the ether-cyano high-pressure electrolyte gel precursor liquid onto the MOF-loaded PET-based separator. Based on casting and direct drying, it is a physical process. After casting, the system can be directly used as a separator support, which can effectively reduce the impact of chemical reactions such as in-situ thermal polymerization or ring-opening polymerization of raw materials on the physicochemical properties of PET nonwoven fabric.

[0057] In some embodiments, the method for preparing the MOF-loaded PET-based separator includes:

[0058] S1, Surface hydrolysis of PET nonwoven fabric

[0059] PET nonwoven fabric is immersed in hydrochloric acid solution, removed, rinsed with deionized water, and dried at room temperature to obtain activated PET nonwoven fabric; in step S1, the PET nonwoven fabric has a loose porous structure, a thickness of 5~100 μm, and a porosity of 20~80%; the immersion time of the PET nonwoven fabric in hydrochloric acid solution is 10~60 minutes, and the concentration of hydrochloric acid solution is 0.01~1 mol / L; by immersing the PET nonwoven fabric in hydrochloric acid solution for hydrolysis, hydroxyl and carboxyl functional groups are introduced onto its fiber surface;

[0060] S2, Surface modification with aminosilane coupling agent

[0061] The activated PET nonwoven fabric obtained in step S1 is immersed in a methanol solution containing an aminosilane coupling agent; the silanol groups generated by the hydrolysis of the aminosilane coupling agent react with the hydroxyl groups on the surface of the nonwoven fabric, thereby achieving the grafting of amino functional groups onto the fiber surface of the PET nonwoven fabric; in step S2, the aminosilane coupling agent is one or more of 3-aminopropyltriethoxysilane (APTES), 3-aminopropyltrimethoxysilane (APTMS), and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (DAMO); the mass percentage of the aminosilane coupling agent in the methanol solution containing the aminosilane coupling agent is 0.1 wt%~1 wt%, and the immersion time is 30 minutes~120 minutes;

[0062] S3, Pre-coordination and fixation of metal ions

[0063] The PET nonwoven fabric treated in step S2 is immersed in a metal ion solution; the metal ions coordinate with the nitrogen atoms in the amino groups grafted onto the fiber surface, thereby being preferentially adsorbed and fixed on the surface of the PET nonwoven fabric; in step S3, the solute in the metal ion solution is one or more of Zn(NO3)2·6H2O, Co(NO3)2·6H2O, ZrCl4, ZrOCl2·8H2O, and Al(NO3)3·9H2O, and the solvent is one or more of DMF, methanol, and deionized water; the mass percentage of the solute in the metal ion solution is 0.1%~6%; the immersion time in the metal ion solution is 1~24 hours;

[0064] In-situ growth of S4 and MOF

[0065] An organic ligand solution is added to the system in step S3, and after thorough mixing, it is allowed to stand at room temperature to obtain PET nonwoven fabric with MOF grown in situ. The ligand molecules diffuse to the fiber surface of the PET nonwoven fabric and coordinate with the fixed metal ions, inducing MOF nuclei to form and grow, achieving heterogeneous nucleation and dense coverage of MOF on the PET surface. In step S4, the organic ligand is a single rigid organic ligand, including one or more of 2-methylimidazolium, terephthalic acid, and trimesic acid. In some preferred embodiments, the organic ligand further includes a bifunctional organic ligand, which includes a fluorinated organic ligand and / or a sulfonic acid-containing organic ligand, wherein the fluorinated organic ligand includes 4-(5-(trifluoromethyl)- 1H-1,2,4-triazol-3-yl)phenol, wherein the sulfonic acid-containing organic ligand includes 2-phenylbenzimidazole-5-sulfonic acid; by combining a single rigid organic ligand and a bifunctional organic ligand, the structural characteristics of fluorine-containing organic ligands and / or sulfonic acid-containing organic ligands can be fully combined, further regulating the surface chemical properties of the MOF; the solvent in the organic ligand solution is one or more of DMF, methanol, and deionized water; the mass percentage of the organic ligand in the organic ligand solution is 3%~14%; the standing time at room temperature is 24~72 hours; when the organic ligand is a single rigid organic ligand and a bifunctional organic ligand, the mass ratio of the single rigid organic ligand to the bifunctional organic ligand is 3~4:1.

[0066] S5. Post-processing to obtain MOF-loaded PET-based separators.

[0067] The PET nonwoven fabric with MOF grown in situ is washed with methanol aqueous solution to remove physically adsorbed or free MOF particles, and then dried at room temperature to obtain a PET-based membrane loaded with MOF (denoted as PET@MOF); in step S5, the volume percentage of methanol in the methanol aqueous solution is 10%~90%.

[0068] In this invention, the MOF-loaded PET-based separator composite ether-cyano high-voltage electrolyte gel electrolyte not only provides mechanical reinforcement but also exhibits an ion sieving effect due to its regular pore structure. Furthermore, by anchoring anions, it effectively inhibits anion migration and increases the lithium-ion transference number. Simultaneously, the MOF surface forms efficient lithium-ion transport pathways, reducing ion migration activation energy and promoting rapid lithium-ion conduction. When combined with the ether-cyano electrolyte components, it forms a weakly solvated structure with lithium ions, promoting the formation of anion-derived interface chemistry. This results in a dense and stable solid electrolyte interphase (CEI / SEI) film on the positive and negative electrode surfaces, improving the battery's cycle stability. Preferably, the MOF-loaded PET-based separator of the present invention is a PET separator with MOF grown in situ on the surface, prepared by first pretreating the PET nonwoven fabric as described above, followed by surface modification with an aminosilane coupling agent, pre-coordination and fixation of metal ions, mixing with an organic ligand solution and post-treatment. This process does not change the macroscopic morphology of the PET nonwoven fabric. The surface of the PET fiber in the MOF-loaded PET-based separator is covered with a continuous and dense MOF layer, which has the characteristics of high pore filling rate, high degree of separator integration and high Young's modulus.

[0069] In some embodiments, the ether-cyano bifunctional high-voltage electrolyte is one or more of 2-(2-methoxyethoxy)acetonitrile (MECN), 2-[2-(2-methoxyethoxy)ethoxy]acetonitrile (DECN), and 2-[2-(2-(2-methoxyethoxy)ethoxy)ethoxy]acetonitrile (TECN); preferably, the ether-cyano bifunctional high-voltage electrolyte is 2-[2-(2-methoxyethoxy)ethoxy]acetonitrile (DECN) and / or 2-[2-(2-(2-methoxyethoxy)ethoxy)ethoxy]acetonitrile (TECN); more preferably, the ether-cyano bifunctional high-voltage electrolyte is 2-[2-(2-(2-methoxyethoxy)ethoxy)ethoxy]acetonitrile (TECN); the CAS number of MECN is 135290-24-3, and the structural formulas of MECN, DECN, and TECN are as follows:

[0070] .

[0071] The ether-cyano bifunctional high-voltage electrolyte of this invention is one or more of 2-(2-methoxyethoxy)acetonitrile (MECN), 2-[2-(2-methoxyethoxy)ethoxy]acetonitrile (DECN), and 2-[2-(2-(2-methoxyethoxy)ethoxy)ethoxy]acetonitrile (TECN). This electrolyte, employing an ether segment combined with a cyano group, avoids defects such as poor compatibility with the negative electrode, synergistically achieving high ionic conductivity and high interfacial stability. It also exhibits high oxidation stability, significantly enhancing the system's antioxidant capacity. Furthermore, it synergistically improves the mechanical and high-voltage electrochemical performance of the electrolyte when used with a MOF-loaded PET-based separator. During the research process, the inventors further discovered that, compared to polycyano molecules, the ether segment combined with a monocyano group in the above-mentioned ether-cyano bifunctional high-voltage electrolyte of this invention exhibits higher ionic conductivity, lithium metal compatibility, and high oxidation stability, resulting in higher mechanical strength and interfacial compatibility in the corresponding composite separator system.

[0072] In some embodiments, the polymer is one or more of polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), and polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP); preferably, the polymer is polyvinylidene fluoride (PVDF) and / or polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), and more preferably, the polymer is polyvinylidene fluoride; the lithium salt is one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(oxalateborate)borate (LiBOB), lithium difluorooxalateborate (LiDFOB), lithium hexafluorophosphate (LiPF6), and lithium perchlorate (LiClO4).

[0073] In some embodiments, the polymer in the ether-cyano high-voltage electrolyte gel precursor solution has a mass percentage content of 2% to 10%, the ether-cyano bifunctional high-voltage electrolyte has a mass percentage content of 2% to 20%, and the lithium salt has a mass percentage content of 1% to 10%.

[0074] On the other hand, a method for preparing a MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte is provided, comprising:

[0075] Provide PET-based separators with MOF loading;

[0076] Preparation of ether-cyano high-voltage electrolyte gel precursor solution: The polymer, ether-cyano bifunctional high-voltage electrolyte, and lithium salt are dissolved together in an organic solvent to obtain a homogeneous and transparent ether-cyano high-voltage electrolyte gel precursor solution; the organic solvent is N,N-dimethylformamide (DMF) or acetonitrile.

[0077] Construction of MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte: The MOF-loaded PET-based membrane is placed in a polytetrafluoroethylene mold, and the ether-cyano high-voltage electrolyte gel precursor solution is poured onto the MOF-loaded PET-based membrane. After vacuum drying, the MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte is obtained. The vacuum drying temperature is 50~70 ℃, and the drying time is 8~48 hours. Vacuum drying can evaporate the solvent and gel the polymer.

[0078] On the other hand, the above-mentioned lithium-ion battery is provided, including the above-mentioned MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte or the MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte prepared by the above method.

[0079] Prior to this application, a series of experiments were conducted. Some of the experimental results are listed below to further describe the invention in detail. The following is a detailed description in conjunction with embodiments. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0080] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this invention pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0081] Example 1

[0082] This embodiment provides a method for preparing a MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte, comprising the following steps:

[0083] (1) Surface pretreatment of PET nonwoven fabric: A PET nonwoven fabric with a thickness of 40 μm and dimensions of [missing information] is prepared. PET nonwoven fabric with a porosity of about 50% was immersed in 100 g of 0.1 mol / L hydrochloric acid solution and hydrolyzed at room temperature for 20 min. After being taken out, it was thoroughly rinsed with deionized water and then dried at room temperature to obtain activated PET nonwoven fabric with a surface rich in hydroxyl and carboxyl groups.

[0084] (2) Modification with aminosilane coupling agent: The activated PET nonwoven fabric obtained in step (1) was immersed in 100 g of methanol solution containing 0.2 wt% (3-aminopropyl)triethoxysilane (APTES) to graft amino functional groups onto the fiber surface. After soaking for 1 h, it was taken out.

[0085] (3) Metal ion pre-fixation: The PET nonwoven fabric treated in step (2) is placed directly in a metal ion solution and soaked at room temperature for 1 hour to allow Zn to be pre-fixed. 2+ It coordinates with surface amino groups and is fixed on the fiber surface; the metal ion solution has the following composition: 0.28 g Zn(NO3)2·6H2O, 14.22 g N,N-dimethylformamide (DMF) and 5.00 g deionized water;

[0086] (4) In-situ growth of MOF: Add organic ligand solution to the system in step (3), mix thoroughly, and let stand at room temperature for 48 h to allow ZIF-8 to nucleate and grow in situ on the PET surface. After the reaction is completed, take out the sample and wash it repeatedly with a methanol / water mixture with a volume ratio of 3:1 to remove the MOF particles that are not firmly bound. After drying at room temperature, a PET-based membrane loaded with MOF (denoted as PET@MOF membrane) is obtained. The organic ligand solution consists of: 0.51 g of 2-methylimidazolium, 0.16 g of 4-(5-(trifluoromethyl)-1H-1,2,4-triazol-3-yl)phenol, 11.86 g of methanol and 5.00 g of deionized water.

[0087] (5) Preparation of ether-cyano high-pressure electrolyte gel precursor solution: 142.25 mg of polyvinylidene fluoride (PVDF), 95 mg of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 284.5 mg of 2-[2-(2-(2-methoxyethoxy)ethoxy)ethoxy]acetonitrile (TECN) were dissolved together in 4 g of DMF and stirred until completely dissolved to form a homogeneous and transparent precursor solution; the molecular weight of the polyvinylidene fluoride was approximately 600,000;

[0088] (6) Assembly of MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte: The PET@MOF membrane obtained in step (4) is placed in a polytetrafluoroethylene mold, the precursor solution prepared in step (5) is poured in, and then placed in a vacuum drying oven at 55 ℃ for 12 h to obtain MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte, denoted as PFPT.

[0089] Comparative Example 1

[0090] To investigate the effects of in-situ MOF growth on the PET surface and the ether-cyano bifunctional high-voltage electrolyte on product performance, this comparative example used unmodified PET nonwoven fabric as the separator, and no TECN was added to the gel precursor solution. To maintain an electrolyte membrane thickness comparable to that of Example 1, the amounts of polymer and lithium salt were increased accordingly to ensure comparability of the film formation.

[0091] The preparation method of this comparative example is as follows: 284.5 mg PVDF and 190 mg LiTFSI were dissolved in 4 g DMF and stirred until completely dissolved to obtain a homogeneous precursor solution; using the PET nonwoven fabric in step (1) of Example 1 as a diaphragm, the above diaphragm was placed in a polytetrafluoroethylene mold, the precursor solution was poured in, and then placed in a vacuum drying oven at 55°C for 12 h to obtain a gel polymer electrolyte, denoted as PP.

[0092] Comparative Example 2

[0093] To investigate the effect of the ether-cyano bifunctional high-voltage electrolyte on product performance, this comparative example uses a technique without TECN. Similarly, to control the consistency of the electrolyte membrane thickness, the amounts of polymer and lithium salt are increased accordingly.

[0094] The preparation method of this comparative example is as follows: 284.5 mg PVDF and 190 mg LiTFSI were dissolved in 4 g DMF and stirred until completely dissolved to obtain a homogeneous precursor solution; the PET@MOF composite membrane prepared in step (4) of Example 1 was used as a supporting skeleton, placed in a polytetrafluoroethylene mold, the precursor solution was poured in, and then placed in a vacuum drying oven at 55 ℃ for 12 h to obtain a gel polymer electrolyte, denoted as PFP.

[0095] Performance Evaluation

[0096] To systematically verify the comprehensive performance of the MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte (PFPT) prepared in this invention, systematic tests and characterization were conducted from multiple dimensions, including microstructure, mechanical properties, ion transport behavior, high-voltage stability, and full-cell performance. The results show that this electrolyte system has significant advantages in structural strength, ion conductivity, high voltage tolerance, and cycle stability, as detailed below:

[0097] 1. Morphological structure and mechanical property characterization

[0098] The microstructure of the diaphragm was analyzed using scanning electron microscopy (SEM), and the results are as follows: Figure 1 As shown, where Figure 1 (a) is a SEM image of the original PET nonwoven fabric. Figure 1 (b) is a SEM image of the PET@MOF membrane prepared in Example 1. Figure 1 As shown in (a), the original PET nonwoven fabric exhibits a typical three-dimensional porous network of interwoven fibers. After in-situ growth of MOF (…), Figure 1 (b) The surface of the PET fiber is uniformly covered by a continuous and dense MOF layer, and the original pores are effectively filled, thus successfully constructing an integrated PET@MOF composite structure.

[0099] The local Young's modulus of the diaphragm was quantitatively measured using atomic force microscopy (AFM) to evaluate its mechanical properties against lithium dendrite penetration. The results are as follows: Figure 2 As shown, where Figure 2 (a) is the AFM of the original PET nonwoven fabric. Figure 2 (b) shows the AFM of the PET@MOF separator prepared in Example 1. It can be seen that the average Young's modulus of the PET@MOF separator is 1.6 GPa, with a maximum value of 3.9 GPa, which are 3.77 times and 5.57 times that of the original PET nonwoven fabric (average value 424.1 MPa, maximum value 701.1 MPa), respectively. This data fully demonstrates that the PET@MOF separator prepared by the method of this invention, with the in-situ grown MOF as a rigid reinforcing phase, can significantly improve the mechanical strength of the separator, providing crucial structural support for effectively suppressing lithium dendrite growth.

[0100] 2. Ion transport performance analysis

[0101] A stainless steel (SS) symmetrical cell (SS|electrolyte|SS) was used, and the ionic conductivity was measured by electrochemical impedance spectroscopy. The results are as follows: Figure 3 As shown in the figure. Calculations showed that the ionic conductivity of PFPT in Example 1 at room temperature was 0.60 mS / cm, significantly higher than that of the comparative examples PP (0.18 mS / cm) and PFP (0.29 mS / cm). Further tests were conducted on the conductivity at different temperatures, and the apparent activation energy was calculated using the Arrhenius formula. The results are shown in the figure. Figure 4 As shown, the activation energies of PP, PFP, and PFPT are 0.32 eV, 0.25 eV, and 0.22 eV, respectively. These results indicate that the in-situ growth of MOF and the introduction of TECN jointly construct a highly efficient lithium-ion transport channel, significantly improving ionic conductivity and optimizing the conduction mechanism.

[0102] Based on a lithium-symmetric battery (Li|electrolyte|Li), the lithium-ion transport number (t) was determined using DC polarization combined with AC impedance spectroscopy. Li + ), the result is as follows Figure 5 As shown, where Figure 5 (a) corresponds to PP in proportion 1. Figure 5 (b) corresponds to PFP of ratio 2. Figure 5 (c) corresponds to the PFPT in Example 1. It can be seen that PP, PFP and PFPT have different t values. Li + The values ​​were 0.39, 0.58, and 0.67, respectively. This indicates that in-situ introduction of MOF to construct the PET@MOF separator can fully utilize the structural confinement effect of MOF and effectively anchor TFSI. -The presence of lithium salt anions promotes selective lithium-ion transport, thereby significantly increasing the migration number. Limiting current density (CCD) test results are as follows... Figure 6 As shown, where Figure 6 (a) corresponds to PP in proportion 1. Figure 6 (b) corresponds to PFP of ratio 2. Figure 6 (c) corresponds to the PFPT in Example 1. As can be seen, the CCD values ​​of the PFP and PFPT electrolytes with in-situ grown MOFs reach 2.7 mA / cm², respectively. 2 With 2.8 mA / cm 2 It is significantly higher than 2.0 mA / cm² for PP. 2 This indicates that the uniform growth of MOF on the PET surface helps optimize the lithium-ion flow distribution, suppress dendrite growth, and improve the rate performance of the battery.

[0103] 3. High-voltage electrochemical stability assessment

[0104] The electrochemical stability window of the lithium-stainless steel asymmetric battery (Li|electrolyte|SS) was evaluated by linear sweep voltammetry (LSV), and the results are as follows: Figure 7 As shown, the PFPT electrolyte exhibits a significantly positive shift in its initial oxidation potential and a significantly broadened stability window, considerably higher than that of the comparative PP and PFP. This confirms that the ether-cyano functional molecule (TECN) combined with the PET@MOF membrane through casting significantly enhances its antioxidant capacity, achieving a stable oxidation window at 4.6 V (vs. Li). + Its stable characteristics at voltages of / Li and higher allow it to be well compatible with high-voltage cathode materials.

[0105] 4. Full Battery Performance Test

[0106] To verify the practical application performance of the electrolyte, a LiNi electrolyte was assembled with lithium metal as the negative electrode. 0.8 Co 0.1 Mn 0.1 A full cell using O2 (NCM811) as the positive electrode. The positive electrode sheet was prepared with an active material: conductive carbon black: polyvinylidene fluoride mass ratio of 8:1:1. The positive electrode slurry was obtained by ball milling in N-methylpyrrolidone at 500 rpm for 6 hours, coated onto an aluminum foil current collector, and then vacuum dried at 80°C. The battery was assembled in an argon glove box (H2O, O2 content <0.01ppm), with the structure being: negative electrode shell / lithium sheet / electrolyte / NCM811 positive electrode sheet / stainless steel sheet / spring sheet / positive electrode shell.

[0107] Rate performance: Discharge performance at different rates was tested within the voltage range of 3.0-4.3 V, and the results are as follows. Figure 8As shown, the PFPT electrolyte exhibits high discharge specific capacity and excellent reversibility in the range of 0.1C to 5C. Especially at a high rate of 5C, its discharge specific capacity still remains at approximately 90.2 mAh / g, which is significantly better than the comparative PP and PFP systems. This is attributed to its high ionic conductivity and optimized interfacial transport kinetics.

[0108] Cyclic stability: Cyclic tests were conducted at 2C rate and a high voltage range of 3.0-4.6V. The results are as follows: Figure 9 and Figure 10 As shown, batteries containing PFP with in-situ MOF and PFPT electrolyte exhibit relatively stable cycle performance, and the PFPT system with high-voltage electrolyte TECN has a higher discharge specific capacity. In contrast, the completely unmodified PP electrolyte cannot complete stable charge and discharge under high voltage, exhibiting a continuous overcharge state. Figure 10 This indicates that the electrolyte system of the present invention can form a stable electrode / electrolyte interface under high voltage, effectively suppressing the continuous decomposition of the electrolyte and the destruction of the positive electrode structure, thereby ensuring the cycle performance of the battery.

[0109] In summary, the PFPT composite gel electrolyte constructed by in-situ growing MOF-enhanced PET separators and introducing ether-cyano high-voltage electrolytes exhibits synergistic improvements in mechanical properties (high Young's modulus), ion transport (high ionic conductivity, high lithium-ion transport number, low activation energy), high-voltage stability (wide electrochemical window), and actual battery performance (excellent rate and cycle performance). It has great potential as a key material for next-generation high-energy-density and high-safety lithium metal batteries.

[0110] Example 2

[0111] This embodiment provides a method for preparing a MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte, comprising the following steps:

[0112] (1) Surface pretreatment of PET nonwoven fabric: A PET nonwoven fabric with a thickness of 40 μm and dimensions of [missing information] is prepared. PET nonwoven fabric with a porosity of about 50% was immersed in 100 g of 0.1 mol / L hydrochloric acid solution and hydrolyzed at room temperature for 30 min. After being taken out, it was thoroughly rinsed with deionized water and then dried at room temperature to obtain activated PET nonwoven fabric with a surface rich in hydroxyl and carboxyl groups.

[0113] (2) Modification with aminosilane coupling agent: The activated PET nonwoven fabric obtained in step (1) was immersed in 100g of methanol solution containing 0.2wt% (3-aminopropyl)triethoxysilane (APTES) to graft amino functional groups onto the fiber surface. After soaking for 1 h, it was taken out.

[0114] (3) Metal ion pre-fixation: The PET nonwoven fabric treated in step (2) is directly placed in a metal ion solution and soaked at room temperature for 1 hour to allow Co to be pre-fixed. 2+ It coordinates with surface amino groups and is fixed on the fiber surface; the metal ion solution has the following composition: Co(NO3)2·6H2O 0.30g, methanol 6.33g and deionized water 2.00g;

[0115] (4) MOF in situ growth: Add organic ligand solution to the system in step (3), mix thoroughly, and let stand at room temperature for 48 h to allow ZIF-67 to nucleate and grow in situ on the PET surface. After the reaction is completed, take out the sample and wash it repeatedly with a methanol / water mixture with a volume ratio of 3:1 to remove the MOF particles that are not firmly bound. After drying at room temperature, a PET-based membrane with MOF loaded with MOF (denoted as PET@MOF membrane) is obtained. The organic ligand solution consists of: 0.39 g of 2-methylimidazolium, 0.88 g of 2-phenylbenzimidazole-5-sulfonic acid, 6.33 g of methanol and 2.00 g of deionized water.

[0116] (5) Preparation of ether-cyano high-voltage electrolyte gel precursor solution: 142.25 mg polyethylene oxide (PEO), 95 mg lithium bis(fluorosulfonyl)imide (LiFSI) and 284.5 mg 2-(2-methoxyethoxy)acetonitrile (MECN) were dissolved together in 4 g acetonitrile and stirred until completely dissolved to form a homogeneous and transparent precursor solution; the molecular weight of the polyethylene oxide was approximately 600,000;

[0117] (6) Assembly of MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte: The PET@MOF membrane obtained in step (4) is placed in a polytetrafluoroethylene mold, the precursor solution prepared in step (5) is poured in, and then placed in a vacuum drying oven at 50°C for 12 h to obtain MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte.

[0118] See Figure 11 In this embodiment, the bulk impedance of the MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte is 61.2 Ω, and its room-temperature ionic conductivity is calculated to be 0.06 mS / cm; see [link to relevant documentation]. Figure 12 In this embodiment, the electrochemical stability window of the MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte is 4.3 V. The relatively narrow electrochemical stability window may be due to the fact that the polymer matrix PEO backbone uses ether bonds (-COC-) as the main structural units, resulting in relatively low thermodynamic stability and kinetic susceptibility to oxidation. Experiments show that the antioxidant decomposition voltage of typical PEO-based electrolytes is usually below 4 V (vs. Li). + / Li). Secondly, the ether-cyano bifunctional additive MECN used in this embodiment has a shorter ether chain in its molecular structure, and its oxidation stability is relatively weaker compared to analogs with longer ether chain structures (such as TECN). The above two factors work synergistically in the system to jointly limit the overall electrochemical stability window of the electrolyte.

[0119] Example 3

[0120] This embodiment provides a method for preparing a MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte, comprising the following steps:

[0121] (1) Surface pretreatment of PET nonwoven fabric: A PET nonwoven fabric with a thickness of 40 μm and dimensions of [missing information] is prepared. A PET nonwoven fabric with a porosity of approximately 50% was immersed in 100g of 0.5mol / L hydrochloric acid solution and hydrolyzed at room temperature for 10min. After being removed, it was thoroughly rinsed with deionized water and then dried at room temperature to obtain an activated PET nonwoven fabric with a surface rich in hydroxyl and carboxyl groups.

[0122] (2) Modification with aminosilane coupling agent: The activated PET nonwoven fabric obtained in step (1) was immersed in 100g of methanol solution containing 0.2 wt% 3-aminopropyltrimethoxysilane (APTMS) to graft amino functional groups onto the fiber surface. After soaking for 1 hour, it was taken out.

[0123] (3) Metal ion pre-fixation: The PET nonwoven fabric treated in step (2) is placed directly in a metal ion solution and soaked at room temperature for 2 hours to allow Zn to be pre-fixed. 2+ It coordinates with surface amino groups and is fixed on the fiber surface; the metal ion solution has the following composition: Zn(NO3)2·6H2O 0.30g, methanol 5.93g and deionized water 2.5g;

[0124] (4) MOF in situ growth: Add organic ligand solution to the system in step (3), mix thoroughly, and let stand at room temperature for 48 h to allow ZIF-8 to nucleate and grow in situ on the PET surface. After the reaction is completed, take out the sample and wash it repeatedly with a methanol / water mixture with a volume ratio of 3:1 to remove the unbonded MOF particles. After drying at room temperature, a PET@MOF composite membrane (denoted as PET@MOF membrane) is obtained. The organic ligand solution consists of 0.66 g of 2-methylimidazole, 5.93 g of methanol and 2.5 g of deionized water.

[0125] (5) Preparation of ether-cyano high-voltage electrolyte gel precursor solution: 142.25 mg of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), 47.5 mg of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), 47.5 mg of lithium difluorooxalate borate (LiDFOB) and 284.5 mg of 2-[2-(2-methoxyethoxy)ethoxy]acetonitrile (DECN) were dissolved together in 4 g of DMF and stirred until completely dissolved to form a homogeneous and transparent precursor solution; the molecular weight of the polyvinylidene fluoride-hexafluoropropylene copolymer was approximately 400,000;

[0126] (6) Assembly of MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte: The PET@MOF membrane obtained in step (4) is placed in a polytetrafluoroethylene mold, the precursor solution prepared in step (5) is poured in, and then placed in a vacuum drying oven at 55°C for 12 hours to obtain MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte.

[0127] See Figure 13 In this embodiment, the bulk impedance of the MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte is 7.83 Ω, and its room-temperature ionic conductivity is calculated to be 0.46 mS / cm; see also Figure 14 In this embodiment, the electrochemical stability window of the MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte is 4.8V.

[0128] Example 4

[0129] This embodiment provides a method for preparing a MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte, comprising the following steps:

[0130] (1) Surface pretreatment of PET nonwoven fabric: A PET nonwoven fabric with a thickness of 50 μm and dimensions of [missing information] is prepared. PET nonwoven fabric with a porosity of about 50% was immersed in 100g of 0.05mol / L hydrochloric acid solution and hydrolyzed at room temperature for 50min. After being taken out, it was thoroughly rinsed with deionized water and then dried at room temperature to obtain activated PET nonwoven fabric with a surface rich in hydroxyl and carboxyl groups.

[0131] (2) Modification with aminosilane coupling agent: The activated PET nonwoven fabric obtained in step (1) was immersed in 100g of methanol solution containing 0.2 wt% (3-aminopropyl)triethoxysilane (APTES) to graft amino functional groups onto the fiber surface. After soaking for 2 h, it was taken out.

[0132] (3) Metal ion pre-fixation: The PET nonwoven fabric treated in step (2) is directly placed in a metal ion solution and soaked at room temperature for 12 h to allow Zr to be pre-fixed. 4+It coordinates with surface amino groups and is fixed on the fiber surface; the metal ion solution has the following composition: ZrCl4 0.50g and DMF 9.44g;

[0133] (4) MOF in situ growth: Add organic ligand solution to the system in step (3), mix thoroughly, and let stand at room temperature for 72 h to allow UiO-66 to nucleate and grow in situ on the PET surface. After the reaction is completed, take out the sample and wash it repeatedly with a methanol / water mixed solution with a volume ratio of 3:1 to remove the MOF particles that are not firmly bound. After drying at room temperature, a PET@MOF composite membrane (denoted as PET@MOF membrane) is obtained. The organic ligand solution consists of 0.5 g terephthalic acid and 7.93 g methanol.

[0134] (5) Preparation of ether-cyano high-pressure electrolyte gel precursor solution: 284.5 mg of polyvinylidene fluoride (PVDF), 190 mg of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 569 mg of 2-[2-(2-(2-methoxyethoxy)ethoxy)ethoxy]acetonitrile (TECN) were dissolved together in 4 g of DMF and stirred until completely dissolved to form a homogeneous and transparent precursor solution;

[0135] (6) Assembly of MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte: The PET@MOF composite membrane obtained in step (4) is placed in a polytetrafluoroethylene mold, the precursor liquid prepared in step (5) is poured in, and then placed in a vacuum drying oven at 60°C for 24 hours to obtain MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte.

[0136] See Figure 15 In this embodiment, the bulk impedance of the MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte is 16.17 Ω, and its calculated room-temperature ionic conductivity is 0.57 mS / cm; see [link to relevant documentation]. Figure 16 In this embodiment, the electrochemical stability window of the MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte is 4.95V.

[0137] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and various changes or modifications can be made to these embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is defined only by the appended claims.

Claims

1. A MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte, characterized in that, The invention includes a PET-based separator supported on MOF and an ether-cyano high-voltage electrolyte gel located on the PET-based separator supported on MOF; the ether-cyano high-voltage electrolyte gel is formed by casting an ether-cyano high-voltage electrolyte gel precursor solution onto the PET-based separator supported on MOF, and the ether-cyano high-voltage electrolyte gel precursor solution includes a polymer, an ether-cyano bifunctional high-voltage electrolyte, a lithium salt, and a solvent.

2. The MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte according to claim 1, characterized in that, The method for preparing the MOF-loaded PET-based separator includes: PET nonwoven fabric is treated with hydrochloric acid solution to obtain activated PET nonwoven fabric. The activated PET nonwoven fabric is then immersed in methanol solution containing aminosilane coupling agent, removed, immersed in metal ion solution, and organic ligand solution is added. After standing at room temperature, PET nonwoven fabric with MOF grown in situ is obtained. The PET nonwoven fabric with MOF grown in situ is washed with methanol aqueous solution and dried to obtain PET-based membrane loaded with MOF.

3. The MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte according to claim 2, characterized in that, The PET nonwoven fabric has a thickness of 5-100 μm and a porosity of 20-80%; the PET nonwoven fabric is immersed in hydrochloric acid solution for 10-60 minutes, and the concentration of the hydrochloric acid solution is 0.01-1 mol / L; and / or, the aminosilane coupling agent is one or more of 3-aminopropyltriethoxysilane (APTES), 3-aminopropyltrimethoxysilane (APTMS), and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (DAMO); the mass percentage of the aminosilane coupling agent in the methanol solution containing the aminosilane coupling agent is 0.1 wt%-1 The metal ion solution contains 0.1 wt% of an aminosilane coupling agent and is immersed in a methanol solution for 30 to 120 minutes; and / or, the solute in the metal ion solution is one or more of Zn(NO3)2·6H2O, Co(NO3)2·6H2O, ZrCl4, ZrOCl2·8H2O, and Al(NO3)3·9H2O, and the solvent in the metal ion solution is one or more of DMF, methanol, and deionized water; the mass percentage of the solute in the metal ion solution is 0.1%. The organic ligand content is 3% to 6%; the immersion time in the metal ion solution is 1 to 24 hours; and / or, the organic ligand includes one or more of 2-methylimidazole, terephthalic acid and trimesic acid, the solvent in the organic ligand solution is one or more of DMF, methanol and deionized water, and the organic ligand content in the organic ligand solution is 3% to 14% by mass; the standing time at room temperature is 24 to 72 hours; and / or, the volume percentage of methanol in the methanol aqueous solution is 10% to 90%.

4. The MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte according to claim 3, characterized in that, The organic ligands also include fluorinated organic ligands and / or organic ligands containing sulfonic acid groups.

5. The MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte according to claim 1, characterized in that, In the ether-cyano high-voltage electrolyte gel precursor solution, the polymer has a mass percentage of 2% to 10%, the ether-cyano bifunctional high-voltage electrolyte has a mass percentage of 2% to 20%, and the lithium salt has a mass percentage of 1% to 10%; and / or, the ether-cyano bifunctional high-voltage electrolyte is one or more of 2-(2-methoxyethoxy)acetonitrile, 2-[2-(2-methoxyethoxy)ethoxy]acetonitrile, and 2-[2-(2-(2-methoxyethoxy)ethoxy)ethoxy]acetonitrile; and / or, the polymer is one or more of polyethylene oxide, polyvinylidene fluoride, and polyvinylidene fluoride-hexafluoropropylene copolymer; and / or, the lithium salt is one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium bis(oxalateborate), lithium difluorooxalateborate, lithium hexafluorophosphate, and lithium perchlorate.

6. The MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte according to claim 5, characterized in that, The ether-cyano bifunctional high-voltage electrolyte is 2-[2-(2-methoxyethoxy)ethoxy]acetonitrile and / or 2-[2-(2-(2-methoxyethoxy)ethoxy)ethoxy]acetonitrile.

7. The MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte according to claim 5, characterized in that, The polymer is polyvinylidene fluoride and / or polyvinylidene fluoride-hexafluoropropylene copolymer.

8. A method for preparing a MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte as described in any one of claims 1 to 7, characterized in that, include: Provide PET-based separators with MOF loading; The polymer, ether-cyano bifunctional high-voltage electrolyte, and lithium salt were dissolved together in an organic solvent to obtain a homogeneous and transparent ether-cyano high-voltage electrolyte gel precursor solution. The MOF-loaded PET-based separator is placed in a polytetrafluoroethylene mold, and the ether-cyano high-voltage electrolyte gel precursor solution is poured onto the MOF-loaded PET-based separator. After vacuum drying, the MOF-loaded PET-based separator composite ether-cyano high-voltage electrolyte gel electrolyte is obtained.

9. The method according to claim 8, characterized in that, The organic solvent is N,N-dimethylformamide (DMF) or acetonitrile; and / or, the vacuum drying temperature is 50~70 °C, and the vacuum drying time is 8~48 hours.

10. A lithium-ion battery, characterized in that, Includes the MOF-loaded PET-based membrane composite ether-cyano high-voltage electrolyte gel electrolyte as described in any one of claims 1 to 7.

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