Conducting ion type MOF material modification-based polymer-based composite solid electrolyte as well as preparation method and application thereof

Abstract

The invention discloses a composite solid electrolyte and a preparation method and application thereof, and belongs to the technical field of solid lithium batteries. The composite solid electrolyte comprises a polymer matrix, a lithium salt and a lithium ion modified ionic metal organic framework (MOF) material. The metal center of the ion-conducting MOF material can be selected from Zr, Ti, Hf and the like, and the organic ligand can be selected from organic acids containing sulfydryl, sulfo groups and the like. The MOF material can effectively inhibit crystallization of a polymer matrix and increase the proportion of an amorphous region, Lewis acid sites on the surface of the MOF material can promote dissociation of lithium salt, and a lithium ion coordination channel formed in the MOF material can provide an extra rapid transmission path for lithium ions. When the electrolyte is applied to the solid-state lithium battery, the growth of lithium dendrites can be effectively inhibited, and the rate capability, the cycling stability and the safety of the battery can be remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to a polymer-based composite solid electrolyte modified with ion-conducting MOF material, a method for preparing the composite solid electrolyte, and the application of the composite solid electrolyte in lithium-ion batteries. Background Technology

[0002] Lithium-ion batteries (LIBs), with their advantages of high energy density, high power density, and flexible design, have been widely used in consumer electronics and electric vehicles, becoming a core component of new energy storage systems. However, current commercial LIBs typically use flammable organic carbonate electrolytes, which are prone to leakage, thermal runaway, and even fires and explosions under long-term cycling or extreme operating conditions. As LIBs develop towards higher energy densities, these safety risks are further aggravated, severely restricting their further development.

[0003] To address the safety hazards of liquid electrolytes, solid electrolytes are widely recognized as the most promising alternative. They not only possess low flammability and ease of processing, but also allow for excellent interfacial contact with electrodes, fundamentally reducing electrolyte-related safety risks. Currently, solid electrolytes are mainly divided into two categories: inorganic solid electrolytes and solid polymer electrolytes (SPEs). While inorganic solid electrolytes possess ionic conductivity comparable to liquid electrolytes, they suffer from brittleness and poor interfacial contact with electrodes, making them unsuitable for practical assembly and cycling requirements. Solid polymer electrolytes (such as polyethylene oxide (PEO)-SPE), on the other hand, have become a research hotspot in recent years due to their lightweight, flexibility, ease of large-scale film formation, and excellent compatibility with electrode interfaces.

[0004] Among various solid polymer electrolytes, PEO-based electrolytes have attracted widespread attention due to their advantages such as good lithium salt solubility, interfacial compatibility with lithium metal electrodes, excellent film-forming properties, and low cost. Their ion conduction mechanism is well-defined: lithium ions migrate between different coordination sites by coordinating with ether oxygen (EO) groups in PEO segments, aided by chain movement, electric field driving, and anion-assisted action. This conduction process mainly occurs in the amorphous regions of PEO. However, PEO has extremely high crystallinity at room temperature, resulting in a low proportion of amorphous regions, which severely limits the lithium ion transport efficiency. Consequently, its room temperature ionic conductivity falls far short of practical application requirements, becoming a core technological obstacle to the industrialization of PEO-based electrolytes.

[0005] To suppress PEO crystallization and improve its ionic conductivity, incorporating inorganic fillers into PEO-based electrolytes has become a mainstream modification strategy, and the electrochemical performance of the electrolyte can be improved to some extent after modification in this way. Based on the differences in filler function, they can be divided into two categories: inert fillers and active fillers. Inert fillers (such as Al2O3, SiO2, TiO2) mainly promote lithium salt dissociation and inhibit PEO molecular chain recrystallization through surface Lewis acid sites, thereby increasing the proportion of amorphous regions; active fillers (such as LLZO, LLZTO) rely on their high ionic conductivity (10⁻⁶ Ω·cm) to achieve this. -4 -10 -3 (S / cm) to build a fast ion transport network inside the electrolyte, while reducing the electrode-electrolyte interface impedance.

[0006] Existing studies have verified the feasibility of this strategy. For example, in his master's thesis "Preparation and Electrochemical Performance Study of Inorganic Composite Polymer Electrolyte Materials," Wang Jian prepared ZrBPMB inorganic filler by spray drying, incorporated it into a mixture of PEO and LiClO4, and prepared PEO by solution casting. 16 -LiClO4-ZrBPMB composite polymer electrolyte. Results showed that ZrBPM effectively reduced the crystallinity of PEO, suppressed recrystallization tendency, and increased the electrolyte ionic conductivity to 5.01 × 10⁻⁶. -6 S cm -1 Simultaneously, the Lewis acid sites of the ZrBPMB skeleton are related to PEO ether oxygen and ClO4. - Oxygen atoms form Lewis acid-base interactions, releasing more free Li. + Participates in conductivity, increases lithium-ion transference number (t) Li+ ).

[0007] However, despite some progress in inorganic filler modification strategies, traditional fillers still suffer from limitations such as single function and strong randomness in ion transport pathways. In recent years, metal-organic frameworks (MOFs), as a new type of porous crystalline material, have provided a new direction for the design of composite solid polymer electrolytes (CSPEs) due to their high specific surface area, tunable pore structure, and well-defined surface chemical properties. MOFs offer multiple advantages as electrolyte fillers: First, their high specific surface area helps enhance the interfacial contact between the filler and the PEO matrix, significantly improving lithium-ion transport by strengthening Lewis acid-base interactions; second, the periodic pore structure of MOFs provides a uniform and directional migration path for lithium ions, effectively reducing ion transport resistance; furthermore, precise control of pore size can achieve cation sieving effects, preferentially promoting lithium-ion migration; finally, the strong adsorption energy of MOFs can capture byproducts generated during battery cycling, helping to stabilize the electrode-electrolyte interface and improve battery cycle stability.

[0008] To further enhance the functional specificity of MOFs as electrolyte fillers, researchers have constructed ion-conducting MOFs with intrinsic ionic conductivity by introducing ion-conducting functional groups (such as anion-anchoring groups) into the MOF framework. These materials can selectively attract cations and repel anions through electrostatic interactions, creating additional lithium-ion transport channels within the electrolyte and enriching active transport sites, thus offering a potential breakthrough in overcoming the limitations of traditional modification strategies.

[0009] However, among the currently disclosed technical solutions, there is a lack of targeted research on "modifying PEO-based solid electrolytes with ion-conducting MOF materials," and even more so, a lack of specific solutions to achieve the preparation of high-performance composite solid electrolytes and significantly improve their core properties such as ionic conductivity and electrochemical stability. This technological gap has prevented the unique advantages of ion-conducting MOFs from being fully utilized in PEO-based electrolyte systems, and has also limited the application of MOF modification strategies in the industrialization process of PEO-based solid electrolytes. Summary of the Invention

[0010] This invention addresses the problems existing in the prior art by proposing a method based on the ion-conducting MOF material Zr-MA-Li. + Modified PEO-based composite solid electrolyte, its preparation method, and its applications. This material is produced using Zr-MA-Li... + The coordination of the thiol group (-SH) with lithium ions constructs a directional transport channel, providing a dense conduction pathway based on the high specific surface area, and effectively restricting anion migration through a tunable framework, thus synergistically promoting efficient lithium ion transport. Specifically, Zr-MA-Li + In the PEO system, it plays a triple role: first, it inhibits PEO crystallization to increase the content of amorphous regions; second, it utilizes surface Lewis acid sites to promote lithium salt dissociation to increase the concentration of free lithium ions; and third, it provides an additional fast lithium ion transport pathway. This study provides a theoretical basis and technical path for the development of high-performance MOF-modified PEO-based solid electrolytes, and promotes the innovation and practical application of this type of electrolyte filler.

[0011] To achieve the above-mentioned technical objectives, the present invention is implemented through the following technical solution:

[0012] A polymer-based composite solid electrolyte modified with lithium-ion-conducting MOF material, wherein the composite solid electrolyte is composed of a polymer matrix, a lithium salt and a lithium-ion-conducting MOF material;

[0013] The lithium-ion-conducting MOF material is a metal-organic framework composed of a metal center M and an organic ligand L, and satisfies at least one of the following structural features: (a) anchoring anionic groups on the inner surface of the MOF framework or pores to carry a fixed negative charge, and using Li⁺ as a charge-compensating cation; and / or (b) utilizing the open metal sites of the MOF to fix lithium salt anions through host-guest chemical fixation, so that lithium ions form selective transport channels inside the MOF, thereby giving the MOF intrinsic lithium-ion conductivity.

[0014] In the composite solid electrolyte, the mass percentage of lithium-ion conductive MOF material is 3-15 wt%, and the molar ratio of polymer matrix to lithium salt is 16:1-24:1; the molar ratio of polymer matrix to lithium salt is 18:1-22:1.

[0015] The polymer matrix is ​​a polyether polymer, a polycarbonate polymer, a polyester polymer, a fluoropolymer, a polyacrylonitrile, a polysiloxane polymer, or their derivatives or copolymers.

[0016] The polymer matrix is ​​selected from the group consisting of: polyethylene oxide (PEO), polypropylene carbonate (PPC), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), and polyacrylonitrile (PAN).

[0017] The metal center M is at least one or a combination of Zr, Hf, Ti, Al, Fe, Cr, V, Nb, Ta, Sn, Ce, Mg, Zn, Co, Ni, and Cu;

[0018] Preferably, the metal center M is Zr and / or Hf.

[0019] The organic ligand L contains a functional group capable of coordinating, ion exchanging, or electrostatically binding with Li⁺, and the functional group is at least one of thiol, carboxyl, sulfonic acid, phosphonic acid, boric acid / borate group, imide-containing or fluorosulfonyl imide anionic group.

[0020] The lithium-ion-conducting MOF material is a lithiated or Li⁺-loaded MOF, and its preparation method includes reacting the MOF precursor ML with a lithium-containing compound to allow Li⁺ to coordinate / exchange ions with ligand functional groups, or to fix lithium salt anions at open metal sites.

[0021] The fixed negative charge or anionic group is at least one of -SO3⁻, -COO⁻, -PO3²⁻, -BO3²⁻, -(CF3SO2)2N-, -FSI⁻ or its derivatives.

[0022] The lithium-ion conductive MOF material is MIT-20-Li or Zr-MA-Li.+ At least one of UIO-66-SO3Li and MOF-688-Li;

[0023] The lithium salt is at least one of LiClO4, LiTFSI, and LiPF6.

[0024] The average particle size of the lithium-ion conductive MOF material is 40-110 nm.

[0025] The lithium-ion-conducting MOF material is a porous crystalline material with a periodic pore structure, the pores being micropores and / or mesopores, used to provide uniform and directional migration channels for Li⁺ and to achieve preferential cation transport;

[0026] The lithium-ion-conducting MOF material has a high specific surface area to enhance its interfacial contact with the polymer matrix and strengthen Lewis acid-base interactions, thereby promoting lithium salt dissociation and Li⁺ transport.

[0027] The intrinsic ionic conductivity of the lithium-ion-conducting MOF material at room temperature is 1.0 × 10⁻⁶. -7 -1.0×10 -5 S·cm -1 ;

[0028] The Li⁺ migration activation energy of the lithium-ion-conducting MOF material is 0.40-0.60 eV;

[0029] The Li⁺ migration activation energy is 0.45-0.51 eV;

[0030] The composite solid electrolyte has an ionic conductivity of 4.0 × 10⁻⁶ at 60 °C. -4 -5.0×10 -4 S·cm -1 ;

[0031] The electrochemical stability window of the composite solid electrolyte is 5.0-5.3 V;

[0032] Compared to polymer electrolytes without lithium-ion-conducting MOF materials, the crystallinity of the polymer in the composite solid electrolyte is reduced to 20-35%;

[0033] The improvement in ionic conductivity of the lithium-ion-conducting MOF material includes at least two or three of the following synergistic mechanisms:

[0034] (a) Inhibits polymer crystallinity and increases the proportion of amorphous phase; (b) Promotes lithium salt dissociation and increases free Li⁺ concentration through Lewis acid sites; (c) Provides additional fast Li⁺ transport channels within the electrolyte;

[0035] The thickness of the composite solid electrolyte membrane is 40-60 μm;

[0036] The mass percentage of the lithium-ion-conducting MOF material is 4-8 wt%.

[0037] Includes the following steps:

[0038] S1. Dissolve the metal source and the organic ligand containing the ion-conducting functional group in solvent A, stir evenly, and then carry out hydrothermal reflux or solvothermal reaction to prepare the MOF precursor ML.

[0039] S2. Dissolve the MOF precursor ML and the lithium-containing compound in solvent B, stir and react to allow Li⁺ to coordinate / ion exchange with ligand functional groups or to fix lithium salt anions, to obtain lithium-ion-conducting MOF material ML-Li⁺.

[0040] S3. The dried polymer and lithium salt are added to an organic solvent suspension containing lithium-ion-conducting MOF material and stirred thoroughly until a homogeneous gel is formed. The gel is then cast into a mold, vacuum dried, and demolded to obtain a polymer-based composite solid electrolyte.

[0041] In step S1, solvent A is at least one of deionized water, ethanol, and N,N-dimethylformamide; the metal source is at least one of zirconium oxychloride, zirconium tetrachloride, zirconium nitrate, zirconium sulfate, and chloride, nitrate, sulfate, or oxysalt corresponding to the metal center of claim 3.

[0042] In step S1, the concentration of the metal source in solvent A is 0.1-2 g / mL, and the concentration of the organic ligand is 0.2-3 g / mL; the reflux / solvent thermal reaction temperature is 80-150℃, and the reaction time is 5-30 min.

[0043] In step S2, solvent B is at least one of PC, DMC, DEC, and DMF; and lithium-containing compound is at least one of LiNO3, LiCl, LiClO4, and LiTFSI.

[0044] In step S2, the concentration of MOF precursor in solvent B is 0.01-2 g / mL, and the concentration of lithium compound is 0.005-1 g / mL; the mixing reaction temperature is 25-40℃, and the reaction time is 4-16 h.

[0045] In step S3, the organic solvent is at least one of acetonitrile, tetrahydrofuran, and dichloromethane; the vacuum drying conditions are a drying temperature of 40-80℃ and a drying time of 12-60 h.

[0046] The dispersion treatment of the lithium-ion-conducting MOF material in step S3 includes ultrasonic dispersion, with an ultrasonic time of 20-40 min.

[0047] An application of the PEO-based composite solid electrolyte is to use the composite solid electrolyte in a solid lithium battery or a solid lithium battery performance testing device as an ion transport medium.

[0048] The solid-state lithium battery includes a positive electrode, a negative electrode, and the composite solid electrolyte layer. The positive electrode active material is at least one of lithium iron phosphate, ternary materials, or lithium cobalt oxide. The negative electrode is at least one of metallic lithium, lithium alloy, or graphite-based materials.

[0049] The solid-state lithium battery performance testing device includes a symmetrical cell or a half-cell.

[0050] The solid-state lithium battery is a lithium metal battery, a power battery, or a lithium battery for consumer electronics.

[0051] The solid-state lithium battery performance testing device is used to verify the ionic conductivity, electrochemical stability window, or lithium dendrite suppression capability of the composite solid electrolyte.

[0052] The above-mentioned Zr-MA-Li based ion-conducting MOF material + The modified PEO-based composite solid electrolyte can be used as an ion transport medium in lithium-ion batteries or lithium-ion battery performance testing devices; the lithium-ion battery includes a positive electrode, a negative electrode and the composite solid electrolyte layer, wherein the positive electrode active material is at least one of lithium iron phosphate (LFP), ternary materials or lithium cobalt oxide, and the negative electrode is at least one of metallic lithium, lithium alloy or graphite-based materials; the lithium-ion battery performance testing device includes symmetrical cells and half cells.

[0053] Furthermore, the lithium-ion battery is a lithium metal battery, a power battery, or a lithium-ion battery for consumer electronics; the lithium-ion battery performance testing device is used to verify the ionic conductivity, electrochemical stability window, or lithium dendrite suppression capability of the composite solid electrolyte.

[0054] The beneficial effects of this invention are as follows:

[0055] 1. This application prepares Zr-MA via hydrothermal reflux and successfully constructs additional ion transport channels by utilizing the coordination of the -SH group in its molecular structure with lithium ions, thereby preparing Zr-MA-Li with ion-conducting properties. + The material has an ionic conductivity of up to 1.6 × 10⁻⁶ at room temperature. -6 S cm -1 Furthermore, the activation energy for lithium-ion migration is only about 0.48 eV. This low activation energy indicates that lithium ions migrate in Zr-MA-Li... +The energy barrier that needs to be overcome during migration in the structure is smaller, which enables efficient ion transport and lays a key material foundation for improving the overall ion conductivity of the electrolyte. It also solves the shortcomings of traditional MOF materials in ion transport efficiency.

[0056] 2. This application will use Zr-MA-Li + Modifying PEO by incorporating it into a PEO matrix significantly improves the thermal stability and mechanical properties of the resulting composite polymer solid electrolyte compared to pure PEO electrolyte, effectively addressing the defects of pure PEO electrolyte such as easy softening at high temperatures and poor mechanical strength. Meanwhile, Zr-MA-Li... + It can interact with PEO molecular chains, significantly reducing the crystallinity of PEO and increasing the proportion of amorphous regions. The increase in amorphous regions can provide more transport paths for lithium ions, further promoting the rapid migration of lithium ions inside the electrolyte. This solves the problem of ion transport obstruction caused by the high crystallinity of pure PEO at the structural level.

[0057] 3. Based on 5 wt% Zr-MA-Li + The modified PEO-based solid electrolyte exhibits an ionic conductivity of 4.47 × 10⁻⁶ at 60 °C. -4 S cm -1 This value not only exceeds the conductivity of the 5 wt% Zr-MA doped composite electrolyte (CSPE-5%Zr-MA) at the same temperature, but is also significantly better than that of pure PEO electrolyte, greatly improving the ion conductivity efficiency of the electrolyte in a mid-temperature environment; Meanwhile, Zr-MA-Li + The introduction of this technology broadens the electrochemical stability window of the composite electrolyte from 4.2 V (pure PEO) to 5.1 V, significantly enhancing the electrolyte's stability in high-voltage systems and avoiding the problem of traditional PEO electrolytes limiting the application of high-voltage cathode materials due to their narrow electrochemical window. Furthermore, CSPE-5%Zr-MA-Li + Compared to pure PEO electrolyte, it has a stronger ability to inhibit lithium dendrite growth, which can effectively prevent the risk of battery short circuit caused by lithium dendrites piercing the electrolyte, greatly improve the safety and cycle stability of the battery, and solve the core safety hazard of solid electrolyte in lithium metal battery applications.

[0058] 4. This application is based on CSPE-5%Zr-MA-Li + Assembled LFP||CSPE-5%Zr-MA-Li +Compared to traditional LFP||PEO||Li full cells, this Li full cell exhibits superior rate performance, maintaining a high discharge capacity even under high-rate (e.g., 2 C) charge-discharge conditions. Furthermore, its lower polarization voltage indicates less energy loss and higher electrochemical reaction efficiency during charge-discharge. Moreover, its overall specific capacity is significantly higher than that of pure PEO full cells, effectively improving energy output and rate cycle stability. This provides a feasible electrolyte solution for the practical application of high-performance lithium metal batteries and demonstrates outstanding potential for industrial application.

[0059] 5. The ion-conducting MOF material (Zr-MA-Li) proposed in this application + The proposed modified PEO-based solid electrolyte not only fills a gap in existing technology, but also has the potential to provide key theoretical basis and feasible technical path for the development of high-performance MOF-modified PEO-based solid electrolytes. This will further promote the innovative design and practical application of functional fillers for this type of electrolyte, and provide a new breakthrough direction for solving core problems such as low room temperature conductivity and insufficient stability of PEO-based electrolytes. Attached Figure Description

[0060] Figure 1 For Zr-MA and Zr-MA-Li + Scanning electron microscope (SEM) images and XRD patterns are shown. Sub-images a and b are SEM images of Zr-MA at different magnifications, respectively. Sub-images c and d are Zr-MA-Li + SEM images at different magnifications, sub-image e represents Zr-MA and Zr-MA-Li. + XRD patterns;

[0061] Figure 2 Zr-MA and Zr-MA-Li + XPS and FT-IR characterization spectra of LiTFSI, with sub-figure a showing Zr–MA and Zr-MA-Li + XPS full spectrum of LiTFSI, subplot b is Zr–MA and Zr-MA-Li + High-resolution XPS S 2p spectra, sub-figure c shows Zr-MA-Li + High-resolution XPS Li 1s spectra from LiTFSI, with sub-plot d representing Zr–MA and Zr-MA-Li. + FT-IR spectrum;

[0062] Figure 3 For Zr-MA and Zr-MA-Li + Thermogravimetric (TG) test curve;

[0063] Figure 4 Neutron diagram a is Zr-MA-Li + Nyquist plot of AC impedance at room temperature, subplot b is Zr-MA-Li + Arrhenius plot of ionic conductivity-temperature relationship;

[0064] Figure 5 The images show SEM images of pure PEO and composite solid electrolytes. Sub-image a is a surface SEM image of pure PEO, sub-image b is a cross-sectional SEM image of pure PEO; sub-image c is a surface SEM image of CSPE-5%Zr-MA, sub-image d is a cross-sectional SEM image of CSPE-5%Zr-MA; sub-image e is a cross-sectional SEM image of CSPE-5%Zr-MA-Li + Surface SEM image, sub-image f is CSPE-5%Zr-MA-Li + SEM image of the cross section;

[0065] Figure 6 The XRD and FTIR spectra of pure PEO and composite solid electrolytes are shown, where sub-figure a represents CSPE-5%Zr-MA and CSPE-5%Zr-MA-Li. + XRD patterns of PEO and PEO, sub-pattern b shows CSPE-5%Zr-MA and CSPE-5%Zr-MA-Li. + FTIR spectra of PEO, sub-figure c shows CSPE-5%Zr-MA and CSPE-5%Zr-MA-Li. + FTIR spectra of PEO;

[0066] Figure 7 For PEO, CSPE-5%Zr-MA and CSPE-5%Zr-MA-Li + The DSC curve;

[0067] Figure 8 Neutron diagram a represents PEO, CSPE-5%Zr-MA, and CSPE-5%Zr-MA-Li. + Thermogravimetric curves, subplot b shows PEO, CSPE-5%Zr-MA, and CSPE-5%Zr-MA-Li. + The stress-strain curve;

[0068] Figure 9 Neutron graph a shows the ionic conductivity of PEO and composite solid electrolytes (CSPE) with different Zr-MA doping ratios as a function of temperature. Subgraph b shows the ionic conductivity of PEO, CSPE-5%Zr-MA, and different Zr-MA-Li... + The ionic conductivity of CSPE with varying doping ratio as a function of temperature;

[0069] Figure 10Linear scan voltammetry of CSPE and PEO at 60℃;

[0070] Figure 11 For Li||PEO||Li and Li||CSPE-5%Zr-MA-Li + ||Li battery at 60℃ and 0.1 mA / cm 2 Charge and discharge voltage curves under the specified conditions;

[0071] Figure 12 Neutron diagram a represents the LFP||PEO||Li full cell and LFP||CSPE-5%Zr-MA-Li. + The rate performance curves of the Li full cell at 60℃ are shown in Figure b, which is the charge-discharge voltage curve of the LFP||PEO||Li full cell. Figure c is the charge-discharge voltage curve of the LFP||CSPE-5%Zr-MA-Li. + || Charge-discharge voltage curve of a Li full cell; Detailed Implementation

[0072] The following embodiments further illustrate the content of the present invention, but should not be construed as limiting the present invention. Any modifications and substitutions made to the methods, steps, or conditions of the present invention without departing from the essence of the invention are within the scope of the present invention.

[0073] Example 1

[0074] This embodiment discloses a method based on the ion-conducting MOF material Zr-MA-Li. + The specific preparation process of the modified PEO-based solid electrolyte is as follows:

[0075] 1) Synthesis of Zr-MA

[0076] 0.75 g of mercaptosuccinic acid (MA) and 2.45 g of ZrCl4 were added to 3 mL of deionized water (DIW) and refluxed in an oil bath at 138 °C for 15 min, forming a white precipitate. After centrifugation to collect the product, it was washed three times each with deionized water and ethanol, and then dried under vacuum at 100 °C for 6 h to obtain Zr-MA powder.

[0077] 2) Zr-MA-Li + Synthesis

[0078] First, 0.11 g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was dissolved in 10 mL of polycarbonate (PC) solvent; then, 0.4 g of Zr-MA prepared in the previous step was added under continuous stirring, and the reaction was carried out at room temperature for 12 h; the resulting sample was washed twice with 10 mL of PC and then dried at 100 °C under vacuum for 3 h to obtain Zr-MA-Li. + powder.

[0079] 3) Preparation of PEO-based composite solid electrolyte

[0080] PEO (molecular weight = 6 × 10) 6 Zr-MA and bis(trifluoromethanesulfonyl)imide (LiTFSI) were dried in a vacuum oven; different amounts of Zr-MA or Zr-MA-Li were weighed. + Add to acetonitrile solution and sonicate for 30 min to form Zr-MA suspensions or Zr-MA-Li with different concentrations. + Suspension: Dried PEO and LiTFSI were added to the above suspension, with a PEO to lithium salt molar ratio of 20:1. After stirring thoroughly for 24 h, a homogeneous gel was formed. The gel was transferred to a polytetrafluoroethylene mold and dried at 60 °C for 48 h to form a composite solid electrolyte film. The entire preparation process was carried out in an argon glove box to ensure an oxygen-free and water-free environment.

[0081] The final mass percentage (wt%) of Zr-MA introduced into the composite solid electrolyte formed by PEO was 3%, 5%, 10% and 15%, respectively, and the resulting electrolytes were denoted as CSPE-3%Zr-MA, CSPE-3%Zr-MA, CSPE-10%Zr-MA and CSPE-15%Zr-MA.

[0082] Zr-MA-Li + Introducing Zr-MA-Li into the composite solid electrolyte formed by PEO + The final mass percentages (wt%) were 3%, 5%, 10%, and 15%, respectively, and the resulting electrolytes were denoted as CSPE-3%Zr-MA-Li. + CSPE-5%Zr-MA-Li + CSPE-10%Zr-MA-Li + CSPE-15%Zr-MA-Li + .

[0083] Related performance tests

[0084] 1. Zr-MA and Zr-MA-Li prepared in steps 1) and 2). + Morphological and structural characterization

[0085] See Figure 1 As seen in the figure, Zr-MA and Zr-MA-Li + The particle size is approximately 40-110 nm. Furthermore, no significant changes in particle morphology or size were observed after adsorption of lithium ions. Figure 1 Neutron diagram (ad). Zr-MA and Zr-MA-Li +XRD pattern ( Figure 1 Neutron diagram e) shows: dried Zr-MA and Zr-MA-Li + The XRD patterns were identical, further proving that the structure of Zr-MA did not change after adsorbing lithium metal ions.

[0086] 2. Characterization of lithium-ion adsorption sites

[0087] To investigate the affinity between metal ions and Zr-MA, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) were used to analyze Zr-MA and Zr-MA-Li. + Characterized by LiTFSI ( Figure 2 The full-spectrum XPS results show that ( Figure 2 Neutron diagram a), Zr-MA does not contain Li + Zr-MA-Li + The presence of characteristic peaks for C, O, Zr, N, S, and Li simultaneously in the sample proves that Li + Successful adsorption. Zr-MA and Zr-MA-Li + High-resolution S 2p XPS spectra ( Figure 2 In neutron diagram b), the S 2p peak of Zr-MA passes through Li + The significant shift after modification indicates that the S atom in the thiol group reacts with the Li. + There are chemical interactions between them. Further analysis of high-resolution Li 1s XPS spectra ( Figure 2 As can be seen in neutron diagram c), Li + The binding energy shifts from 56.7 eV in LiTFSI to Zr-MA-Li + The 53.5 eV in the figure confirms that Li + It forms a coordination relationship with the S atom. FT-IR spectrum ( Figure 2 Neutron plot d) further corroborates this conclusion: Zr-MA at 2550 cm⁻¹ -1 The characteristic peaks of thiol (-SH) groups near Zr-MA-Li + The complete disappearance of the -SH group indicates that it participated in the interaction with Li. + The above results collectively indicate that the thiol groups in Zr-MA can achieve coordination with Li through S-Li coordination. + Effective adsorption.

[0088] 3. Zr-MA and Zr-MA-Li + Thermal stability test

[0089] Dry Zr-MA and Zr-MA-Li +In thermogravimetric (TG) tests, the mass changes with increasing temperature in a consistent manner, exhibiting a slow decrease followed by stabilization. This indicates that both materials possess excellent thermal stability under high-temperature conditions, and their thermal stability performance is similar. Figure 3 ).

[0090] 4. Zr-MA-Li + Ionic conductivity test

[0091] Zr-MA-Li was prepared by powder compression method. + After sampling, the ionic conductivity was measured by AC impedance spectroscopy. During measurement, a pellet was clamped between two stainless steel electrodes. Zr-MA-Li obtained under these conditions... + Nyquist plot ( Figure 4 Neutron plot a) exhibits two typical regions: the high-frequency region is a semi-circular arc, corresponding to the total impedance of ions passing through the material's crystal structure, grain boundaries, and interparticle contact interfaces; the low-frequency region shows a linear tail, reflecting the blocking electrode effect. Through fitting calculations, Zr-MA-Li + The ionic conductivity at room temperature is approximately 1.6 × 10⁻⁶. -6 S cm -1 .

[0092] To quantitatively characterize the difficulty of lithium-ion migration, Zr-MA-Li was further measured in the temperature range of 30°C to 80°C. + The AC impedance spectrum was obtained. Based on the ionic conductivity data at different temperatures, an Arrhenius plot (ln(σT) versus 1000 / T, where T is the absolute temperature (K)) was plotted, as shown below. Figure 4 As shown in neutron plot b, ln(σT) exhibits a good linear relationship with 1000 / T. Based on the Arrhenius relation, the Zr-MA-Li value is calculated from the slope of the linear fit. + The activation energy for lithium-ion migration in Zr-MA-Li is approximately 0.48 eV. This relatively low activation energy indicates that lithium ions migrate in Zr-MA-Li + The structure has a relatively small energy barrier to overcome during migration, which is conducive to achieving high ion transport.

[0093] 5. Structural characterization of PEO-based composite solid electrolytes

[0094] SEM images of pure PEO solid electrolyte and composite solid electrolyte are as follows: Figure 5 As shown in the figure, there are significant differences in the microstructure between the pure PEO solid electrolyte and the composite solid electrolyte. The composite solid electrolytes (CSPE-5%Zr-MA and CSPE-5%Zr-MA-Li) +The surface of CSPE-5%Zr-MA is smoother than that of pure PEO. CSPE-5%Zr-MA shows no obvious particle agglomeration, while CSPE-5%Zr-MA-Li... + A small number of nanoscale aggregates were present on the surface, but none of them had large-sized defects, indicating that the MOF particles were well dispersed in the PEO matrix. Cross-sectional SEM images showed that the thickness of the composite solid electrolyte was approximately 50 μm, with no macroscopic agglomeration of MOF particles in the cross-section, indicating good overall dispersion. This uniform dispersion structure is beneficial for improving the performance of the electrolyte.

[0095] 6. Crystallinity Analysis of PEO-based Composite Solid Polymer Electrolytes

[0096] To investigate the composition and crystallinity variations of the composite solid electrolyte, XRD characterization was performed. Figure 6 As shown in neutron diagram a, pure PEO exhibits two strong characteristic peaks at 19° and 23°, corresponding to the typical crystal structure of PEO, indicating its high crystallinity. When Zr-MA or Zr-MA-Li is added... + Subsequently, the intensity of the crystallization peak of PEO decreased and the half-peak width increased, indicating that the interaction between MOF and PEO matrix disrupted the long-range ordered arrangement of PEO molecular chains, increased the proportion of amorphous regions, and led to a decrease in the crystallinity of PEO.

[0097] FTIR testing further verified the structural changes of the composite electrolyte. Figure 6 Neutron diagrams b and c). In pure PEO electrolyte, 842 cm⁻¹ -1 The absorption peak at that location corresponds to TFSI - SNS symmetric vibration; while in CSPE-5%Zr-MA and CSPE-5%Zr-MA-Li + In the middle, the peak position shows a significant redshift ( Figure 6 (Neutron diagram b) This may be due to the interaction between metal ions in the MOF and TFSI. - The formation of Lewis acid-base pairs weakens the Li + With TFSI - The electrostatic effect promotes the free Li + The dissociation of PEO. Furthermore, the characteristic crystallization peak of PEO (1356 cm⁻¹) is observed. -1 and 1346 cm -1 The -CH2- bending vibration double peak at 1144 cm⁻¹, and the 1144 cm⁻¹ peak at 1144 cm⁻¹. -1 1113 cm -1 and 1061 cm -1 The intensity of the -COC- stretching vibration ternary peak at the position is significantly weakened in the composite electrolyte. Figure 6The bent double peak of -CH2- and the stretched ternary peak of -COC- in neutron diagram c) are thought to be related to crystallized PEO, further confirming that the introduction of MOF interferes with the crystallization arrangement of PEO through interfacial interactions, resulting in a decrease in its crystallinity.

[0098] Differential scanning calorimetry (DSC) was used to further investigate the phase transition behavior of PEO, and the results are as follows: Figure 7 As shown, the glass transition temperature (T) of pure PEO solid electrolyte is... g ) and melting temperature (T) m The temperatures were -39.9℃ and 58.6℃ respectively. After adding Zr-MA, T... g and T m The temperatures were lowered to -47.25℃ and 52.67℃ respectively, introducing lithiation-treated Zr-MA-Li. + At that time, T g and T m The temperatures were further reduced to -47.96℃ and 51.61℃. These results indicate that Zr-MA and Zr-MA-Li... + The introduction of [a specific substance] allows the electrolyte to form more amorphous regions, which is beneficial for ion transport.

[0099] Based on DSC data, the changes in melting enthalpy and calculated crystallinity of the composite solid electrolyte are listed in Table 1. The results show that after adding 5 wt% Zr-MA to the electrolyte, the crystallinity decreased from 53.21% to 34.19%. When 5 wt% Zr-MA-Li was added... + Subsequently, the crystallinity further decreased to 31.84%. This is due to the crystallinity of Zr-MA and Zr-MA-Li. + The addition of [agent] increased the proportion of amorphous phase in the electrolyte and enhanced the mobility of PEO chain segments, a result consistent with XRD analysis.

[0100] Table 1. PEO, CSPE-5%Zr-MA and CSPE-5%Zr-MA-Li + Enthalpy change and crystallinity

[0101] <![CDATA[ΔH m ]]> Crystallinity PEO 65.31 J / g 53.21% CSPE -5% Zr-MA 41.97 J / g 34.19% <![CDATA[CSPE -5%Zr-MA-Li + ]]> 39.08 J / g 31.84%

[0102] 7. Thermal stability test of PEO-based composite solid polymer electrolyte

[0103] Thermogravimetric analysis (TG, Figure 8 Neutron plot a) results show that the composite solid electrolyte (CSPE) exhibits excellent thermal stability: CSPE-5%Zr-MA-Li +It maintains structural stability up to 350℃, exhibiting significantly better thermal stability than flammable organic liquid electrolytes. When the temperature rises to 350-450℃, CSPE undergoes irreversible decomposition, corresponding to the decomposition process of the PEO matrix and LiTFSI. At 600℃, CSPE-5%Zr-MA and CSPE-5%Zr-MA-Li... + The residual mass of CSPE-5%Zr-MA-Li is higher than that of pure PEO. + The highest residual amount was observed. This is attributed to Zr-MA and Zr-MA-Li. + Its excellent thermal stability ensures that the lithium metal batteries (LMBs) assembled from it can operate safely in high-temperature environments.

[0104] The mechanical properties of polymer electrolytes are crucial for the safe operation of lithium-ion batteries (LIBs). Tensile test results ( Figure 8 Neutron plot b) shows that the strain of the PEO-based composite solid electrolyte with Zr-MA incorporation is significantly higher than that of pure PEO, while that of Zr-MA-Li... + The addition of MOF further enhances the flexibility of the composite electrolyte. This indicates that the introduction of MOF can reduce the risk of tearing and rupture of the electrolyte membrane under high tensile conditions, thereby helping LIBs to effectively suppress or delay the occurrence of short circuits during cycling.

[0105] 8. Electrochemical performance testing of PEO-based composite solid electrolyte

[0106] 1) Ionic conductivity test

[0107] To study Zr-MA and Zr-MA-Li + To investigate the effect of PEO polymer electrolyte on improving ionic conductivity, an SS / CSPE / SS battery (SS being a stainless steel electrode and CSPE a composite solid electrolyte) was assembled and impedance tests were conducted within the temperature range of 30–80 °C. The results showed that… Figure 9 As shown in neutron diagram a, within the test temperature range, the ionic conductivity of CSPE containing Zr-MA (CSPE-Zr-MA) is higher than that of pure PEO solid electrolyte at any temperature, and the ionic conductivity of CSPE reaches its highest value when the Zr-MA doping ratio is 5 wt%.

[0108] To compare the effect of lithium-ion MOFs on conductivity, this application also prepared different Zr-MA-Li... + Composite electrolytes with varying doping ratios, by Figure 9 Neutron diagram b shows that: Zr-MA-Li + The optimal doping ratio is also 5 wt%, and under these conditions, the CSPE exhibits an ionic conductivity of 4.47 × 10⁻⁶ at 60 °C. -4 S cm -1This value is not only higher than the conductivity of CSPE-5%Zr-MA at the same temperature, but also significantly better than that of pure PEO electrolyte, confirming that the lithiation of MOF has a more prominent effect on improving the conductivity of PEO electrolyte.

[0109] It is worth noting that when Zr-MA or Zr-MA-Li + When the doping ratio exceeds 5 wt%, the ionic conductivity shows a downward trend. This may be because the excessive MOF content leads to particle agglomeration and also damages the interfacial compatibility between MOF and PEO matrix. These two factors together hinder the transport path of lithium ions, ultimately resulting in a decrease in conductivity.

[0110] 2) Electrochemical window testing of PEO-based composite solid polymer electrolyte

[0111] To evaluate the electrochemical stability of the composite solid electrolyte, linear sweep voltammetry (LSV) was used. A Li / CSPE / SS battery was employed as the research subject, and tests were conducted at a test temperature of 60℃ within a voltage range of 3 V to 6 V. The results are as follows: Figure 10 As shown. Test data shows that the electrochemical stability window of pure PEO-based solid electrolyte is 4.2 V; when Zr-MA is introduced, the electrochemical stability window of CSPE-5%Zr-MA is significantly increased to 4.7 V; while the electrochemical stability window of lithiated Zr-MA-Li... + During modification, CSPE-5%Zr-MA-Li + The electrochemical stability window was further improved to 5.1 V, which is the best performance.

[0112] The above results indicate that both unlithiated Zr-MA and lithiated Zr-MA-Li + When Zr-MA-Li is introduced into PEO-based solid electrolytes as a MOF material, it can effectively enhance the electrochemical stability of the electrolyte. + The improvement in stability is more significant, providing a more reliable performance guarantee for the application of electrolytes in high-voltage systems.

[0113] 3) Performance testing of Li||CSPE|||Li symmetric cells

[0114] To further evaluate the electrolyte's ability to suppress lithium dendrite growth, a Li-Li symmetric cell was used as the research object in the experiment, with a current density of 0.1 mA / cm². 2 The polarization voltage and cycle life of the battery were tested at a test temperature of 60℃, and the results are as follows: Figure 11 As shown.

[0115] Test results show that: CSPE-5%Zr-MA-Li +The assembled Li-Li symmetric battery maintained stable operation throughout the test, with a cycle life of up to 270 hours; while the Li-Li symmetric battery assembled with pure PEO electrolyte experienced a short circuit after only 160 hours of operation and could not continue to cycle stably.

[0116] The aforementioned performance differences clearly demonstrate that, compared to pure PEO electrolyte, CSPE-5%Zr-MA-Li + It has a stronger ability to suppress lithium dendrite growth, which can effectively avoid battery short circuits caused by lithium dendrites piercing the electrolyte, further highlighting the advantages of this composite solid electrolyte in improving battery safety and cycle stability.

[0117] 4) Performance testing of LFP||CSPE|||Li full cells

[0118] To further comprehensively evaluate CSPE-5%Zr-MA-Li + The electrochemical performance was assessed by experimentally assembling LFP||CSPE-5%Zr-MA-Li + A Li-based full cell (where LFP is the lithium iron phosphate cathode and Li is the lithium metal anode) was tested at a constant temperature of 60°C. The specific results are analyzed below:

[0119] Two types of full cells (LFP||PEO||Li and LFP||CSPE-5%Zr-MA-Li) + The rate performance test results of ||Li) are as follows Figure 12 Neutron diagram a is shown. Data shows that the discharge capacity of the LFP||PEO||L battery at different rates is: 152.9 mAhg at 0.1 C. -1 149.5 mAh g at 0.2 C -1 141.2 mAh g at 0.5 C -1 127.2 mAh g at 1 C -1 2C at 94.6 mAh g -1 As the rate of increase increases, the capacity decay becomes more pronounced; while LFP||CSPE-5%Zr-MA-Li + The Li-ion battery exhibits superior capacity performance at the same discharge rate, with a discharge capacity of 158.6 mAh g at 0.1 C. -1 157.7 mAh g at 0.2 C -1 152.2 mAh g at 0.5 C -1 142.3 mAh g at 1 C -1 125.1 mAh g at 2 C -1 The capacity decay rate is significantly smaller than that of the pure PEO system.

[0120] Of particular importance, when the current density recovers to 0.1 C, LFP||CSPE-5%Zr-MA-Li + The discharge capacity of Li batteries is still higher than that of LFP and PEO Li batteries, indicating that they have stronger capacity recovery capability and better rate stability after variable rate cycling.

[0121] from Figure 12 The charge-discharge voltage curves shown in neutron diagrams b and c allow for a direct observation of the following: (The text abruptly ends here, likely due to an incomplete sentence or a formatting error.) + LFP||CSPE-5%Zr-MA-Li assembled with composite solid electrolyte + The polarization voltage between the charge and discharge plateaus of the CSPE-5%Zr-MA-Li full cell is significantly lower than that of the LFP-PEO-Li full cell assembled from pure PEO-based solid electrolyte. In electrochemical systems, the magnitude of the polarization voltage is directly related to the degree of energy loss within the battery: a lower polarization voltage indicates less charge transfer resistance at the electrode-electrolyte interface during charge-discharge cycles, resulting in higher lithium-ion transport efficiency at the interface and thus improving the overall efficiency of the electrochemical reactions within the battery. This test result further confirms the effectiveness of CSPE-5%Zr-MA-Li. + Its significant role in optimizing full-cell interface compatibility, reducing interface impedance, and improving battery energy utilization efficiency logically echoes the advantages demonstrated in the rate performance test mentioned earlier.

[0122] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. However, the above description is merely a specific embodiment of the present invention, and the technical features of the present invention are not limited thereto. Any other embodiments derived by those skilled in the art without departing from the technical solution of the present invention should be covered within the scope of the present invention.

Claims

1. A polymer-based composite solid electrolyte modified with lithium-ion MOF material, characterized in that, The composite solid electrolyte is composed of a polymer matrix, a lithium salt, and a lithium-ion conductive MOF material. The lithium-ion-conducting MOF material is a metal-organic framework composed of a metal center M and an organic ligand L, and satisfies at least one of the following structural features: (a) anchoring anionic groups on the inner surface of the MOF framework or pores to carry a fixed negative charge, and using Li⁺ as a charge-compensating cation; and / or (b) utilizing the open metal sites of the MOF to fix lithium salt anions through host-guest chemical fixation, so that lithium ions form selective transport channels inside the MOF, thereby giving the MOF intrinsic lithium-ion conductivity.

2. The composite solid electrolyte according to claim 1, characterized in that, In the composite solid electrolyte, the mass percentage of lithium-ion conductive MOF material is 3-15 wt%, and the molar ratio of polymer matrix to lithium salt is 16:1-24:1; the molar ratio of polymer matrix to lithium salt is 18:1-22:

1. The polymer matrix is ​​a polyether polymer, a polycarbonate polymer, a polyester polymer, a fluoropolymer, a polyacrylonitrile, a polysiloxane polymer, or their derivatives or copolymers.

3. The composite solid electrolyte as described in claim 1 or 2, characterized in that, The metal center M is at least one or a combination of Zr, Hf, Ti, Al, Fe, Cr, V, Nb, Ta, Sn, Ce, Mg, Zn, Co, Ni, and Cu; Preferably, the metal center M is Zr and / or Hf.

4. The composite solid electrolyte according to any one of claims 1-3, characterized in that, The organic ligand L contains a functional group capable of coordinating, ion exchanging, or electrostatically binding with Li⁺, and the functional group is at least one of thiol, carboxyl, sulfonic acid, phosphonic acid, boric acid / borate group, imide-containing or fluorosulfonyl imide anionic group. The lithium-ion-conducting MOF material is a lithiated or Li⁺-loaded MOF, and its preparation method includes reacting the MOF precursor ML with a lithium-containing compound to allow Li⁺ to coordinate / exchange ions with ligand functional groups, or to fix lithium salt anions at open metal sites. The fixed negative charge or anionic group is at least one of -SO3⁻, -COO⁻, -PO3²⁻, -BO3²⁻, -(CF3SO2)2N-, -FSI⁻ or its derivatives.

5. The composite solid electrolyte as described in claim 1, characterized in that, The lithium-ion conductive MOF material is MIT-20-Li or Zr-MA-Li. + At least one of UIO-66-SO3Li and MOF-688-Li; The lithium salt is at least one of LiClO4, LiTFSI, and LiPF6.

6. The composite solid electrolyte according to any one of claims 1-5, characterized in that, The average particle size of the lithium-ion conductive MOF material is 40-110 nm. The lithium-ion-conducting MOF material is a porous crystalline material with a periodic pore structure, the pores being micropores and / or mesopores, used to provide uniform and directional migration channels for Li⁺ and to achieve preferential cation transport; The lithium-ion-conducting MOF material has a high specific surface area to enhance its interfacial contact with the polymer matrix and strengthen Lewis acid-base interactions, thereby promoting lithium salt dissociation and Li⁺ transport. The intrinsic ionic conductivity of the lithium-ion-conducting MOF material at room temperature is 1.0 × 10⁻⁶. -7 -1.0×10 -5 S·cm -1 ; The Li⁺ migration activation energy of the lithium-ion conductive MOF material is 0.40-0.60 eV; The Li⁺ migration activation energy is 0.45-0.51 eV; The composite solid electrolyte has an ionic conductivity of 4.0 × 10⁻⁶ at 60 °C. -4 -5.0×10 -4 S·cm -1 ; The electrochemical stability window of the composite solid electrolyte is 5.0-5.3V; Compared to polymer electrolytes without lithium-ion-conducting MOF materials, the crystallinity of the polymer in the composite solid electrolyte is reduced to 20-35%; The improvement in ionic conductivity of the lithium-ion-conducting MOF material includes at least two or three of the following synergistic mechanisms: (a) Inhibits polymer crystallinity and increases the proportion of amorphous phase; (b) Promotes lithium salt dissociation and increases free Li⁺ concentration through Lewis acid sites; (c) Provides additional fast Li⁺ transport channels within the electrolyte; The thickness of the composite solid electrolyte membrane is 40-60 μm; The mass percentage of the lithium-ion-conducting MOF material is 4-8 wt%.

7. A method for preparing a polymer-based composite solid electrolyte as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Dissolve the metal source and the organic ligand containing the ion-conducting functional group in solvent A, stir evenly, and then carry out hydrothermal reflux or solvothermal reaction to prepare the MOF precursor ML. S2. Dissolve the MOF precursor ML and the lithium-containing compound in solvent B, stir and react to allow Li⁺ to coordinate / ion exchange with ligand functional groups or to fix lithium salt anions, to obtain lithium-ion-conducting MOF material ML-Li⁺. S3. The dried polymer and lithium salt are added to an organic solvent suspension containing lithium-ion-conducting MOF material and stirred thoroughly until a homogeneous gel is formed. The gel is then cast into a mold, vacuum dried, and demolded to obtain a polymer-based composite solid electrolyte.

8. The preparation method according to claim 7, characterized in that, In step S1, solvent A is at least one of deionized water, ethanol, and N,N-dimethylformamide; the metal source is at least one of zirconium oxychloride, zirconium tetrachloride, zirconium nitrate, zirconium sulfate, and chloride, nitrate, sulfate, or oxysalt corresponding to the metal center of claim 3. In step S1, the concentration of the metal source in solvent A is 0.1-2 g / mL, and the concentration of the organic ligand is 0.2-3 g / mL; the reflux / solvent thermal reaction temperature is 80-150℃, and the reaction time is 5-30 min. In step S2, solvent B is at least one of PC, DMC, DEC, and DMF; and lithium-containing compound is at least one of LiNO3, LiCl, LiClO4, and LiTFSI. In step S2, the concentration of MOF precursor in solvent B is 0.01-2 g / mL, and the concentration of lithium compound is 0.005-1 g / mL; the mixing reaction temperature is 25-40℃, and the reaction time is 4-16 h. In step S3, the organic solvent is at least one of acetonitrile, tetrahydrofuran, and dichloromethane; the vacuum drying conditions are a drying temperature of 40-80℃ and a drying time of 12-60 h. The dispersion treatment of the lithium-ion-conducting MOF material in step S3 includes ultrasonic dispersion, with an ultrasonic time of 20-40 min.

9. The application of a polymer-based composite solid electrolyte as described in any one of claims 1-6, characterized in that, The composite solid electrolyte is used in solid-state lithium batteries or solid-state lithium battery performance testing devices as an ion transport medium. The solid-state lithium battery includes a positive electrode, a negative electrode, and the composite solid electrolyte layer. The positive electrode active material is at least one of lithium iron phosphate, ternary materials, or lithium cobalt oxide. The negative electrode is at least one of metallic lithium, lithium alloy, or graphite-based materials. The solid-state lithium battery performance testing device includes a symmetrical cell or a half-cell.

10. The application as described in claim 9, characterized in that, The solid-state lithium battery is a lithium metal battery, a power battery, or a lithium battery for consumer electronics. The solid-state lithium battery performance testing device is used to verify the ionic conductivity, electrochemical stability window, or lithium dendrite suppression capability of the composite solid electrolyte.

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