Preparation method and application of MOF-based all-solid-state electrolyte

Abstract

This invention discloses a method for preparing a MOF-based all-solid-state electrolyte and its application, comprising: dissolving 4-cyanopyridine and a nickel salt in a solvent and mixing them; filtering, washing, drying, and grinding the resulting product into powder to obtain Ni-4QBD; dissolving lithium bis(trifluoromethanesulfonylimide) and Ni-4QBD in a solvent and mixing them; filtering, washing, drying, and grinding the resulting product into powder to obtain Ni-4QBD(Li + ); Ni-4QBD(Li + The raw materials are evenly spread in a mold and then hot-pressed. This method has the advantages of inexpensive and readily available raw materials, simple and clear composition, convenient synthesis process, and large-scale preparation, and is expected to be suitable for large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of all-solid-state electrolyte preparation technology, specifically relating to a method for preparing MOF-based all-solid-state electrolytes and their applications. Background Technology

[0002] The main difference between solid-state electrolytes and all-solid-state electrolytes lies in their composition and the substances they contain. All-solid-state electrolytes are the core material of all-solid-state batteries, offering higher safety and greater potential for energy density improvement compared to traditional liquid electrolytes. The development of solid-state electrolytes can further improve ionic conductivity, create novel solid-state electrolyte materials, enhance the performance of all-solid-state batteries, and drive the development of solid-state ion science. Furthermore, the physicochemical processes in all-solid-state batteries, such as ion transport and interfacial electrochemistry, exhibit distinct multi-field coupling characteristics, making all-solid-state batteries a very promising candidate for application in the energy storage industry.

[0003] MOFs (Metal-Organic Flocculants) are crystalline materials composed of metal ions and organic ligands, exhibiting highly tunable and diverse structural characteristics. These properties have led to their widespread study in electrochemistry, particularly as electrolytes for energy storage devices such as batteries and supercapacitors. However, these studies only focus on MOF-based solid-state electrolytes; the preparation of MOF-based all-solid-state electrolytes remains under development, facing several challenges and limitations. For example:

[0004] 1. Structural diversity of MOFs: MOFs possess a wide variety of structures and compositions, which complicates the design and synthesis of MOF materials suitable for all-solid-state electrolytes. Selecting a suitable MOF structure to provide sufficient ion conduction performance is a challenge.

[0005] 2. Lack of suitable ion channels: The preparation of all-solid-state electrolytes requires the introduction of effective ion channels into MOFs to enable ions to move between the crystal lattice. However, many MOF structures themselves do not possess good ion conduction properties, thus requiring structural modification of MOFs or the introduction of other functional components to enhance the effectiveness of their ion channels.

[0006] 3. Thermal Stability and Mechanical Properties: All-solid-state electrolytes require high thermal stability and good mechanical properties to withstand extreme conditions such as high temperatures, cooling, and cycling. However, most current MOF materials experience instability, decomposition, or collapse at high temperatures, and their mechanical properties are relatively poor. Therefore, there is a need to develop more stable MOF materials with higher mechanical strength as all-solid-state electrolytes.

[0007] 4. Optimization of electrochemical performance: Although some MOF materials exhibit certain ion conduction properties, their electrochemical performance still needs further optimization. For example, improvements in ion migration rate, interfacial impedance, and electrochemical stability are key to the preparation of high-performance all-solid-state electrolytes.

[0008] 5. Using these MOF powders directly as solid electrolytes to study their conduction mechanisms in practical batteries is extremely difficult. Many questions remain unresolved, such as the spatial distribution of these crystalline nanomaterials in the solid electrolyte layer and the actual migration routes of metal ions.

[0009] In summary, the main reasons why MOF-based all-solid-state electrolytes are currently difficult to prepare include structural diversity, lack of good ion channels, limitations in thermal stability and mechanical properties, and the need to optimize electrochemical performance. These problems require further research and exploration to overcome in order to achieve the preparation of high-performance MOF-based all-solid-state electrolytes. Summary of the Invention

[0010] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly describe some preferred embodiments.

[0011] As one aspect of this invention, this invention provides a method for preparing a MOF-based all-solid-state electrolyte, comprising,

[0012] (1) Dissolve 4-cyanopyridine and nickel salt in a solvent and mix them;

[0013] (2) The product obtained in step (1) is filtered, washed, dried and ground into powder to obtain Ni-4QBD;

[0014] (3) Dissolve lithium bis(trifluoromethanesulfonylimide) and Ni-4QBD in a solvent and mix them;

[0015] (4) The product obtained in step (3) is filtered, washed, dried, and ground into powder to obtain Ni-4QBD(Li + );

[0016] (5) Ni-4QBD(Li + The mixture is evenly spread in a mold and hot-pressed to obtain a MOF-based all-solid electrolyte.

[0017] As a preferred embodiment of the preparation method of the MOF-based all-solid electrolyte of the present invention: in step (1), the nickel salt includes nickel nitrate, and the molar ratio of 4-cyanopyridine to nickel salt is 4:1.

[0018] As a preferred embodiment of the preparation method of the MOF-based all-solid electrolyte of the present invention: in step (1), the solvent includes methanol, and the concentration of 4-cyanopyridine is 0.5-1M; the mixing includes stirring and mixing for 1-2 hours.

[0019] As a preferred embodiment of the preparation method of the MOF-based all-solid electrolyte of the present invention: in step (2), the drying includes drying the sample at 50-60°C.

[0020] As a preferred embodiment of the preparation method of the MOF-based all-solid electrolyte of the present invention: in step (3), the mass ratio of lithium bis(trifluoromethanesulfonylimide) to Ni-4QBD is 1:1.5.

[0021] As a preferred embodiment of the preparation method of the MOF-based all-solid-state electrolyte of the present invention: in step (3), the solvent includes N-methylpyrrolidone; the mixing includes stirring and mixing for 48 to 72 hours; and the concentration of lithium bis(trifluoromethanesulfonyl)imide is 5 to 10%.

[0022] As a preferred embodiment of the preparation method of the MOF-based all-solid electrolyte of the present invention: in step (4), the drying includes drying the sample at 50-60°C.

[0023] As a preferred embodiment of the preparation method of the MOF-based all-solid electrolyte of the present invention: in step (5), the hot pressing includes hot pressing for 2 to 3 hours at 100 to 120°C and 45 to 50 MPa.

[0024] The beneficial effects of this invention: This invention provides a method for preparing a MOF-based all-solid-state electrolyte. Firstly, this invention attempts to use pyridine-based materials with cyano functional groups as ligands. Experimental results show that the cyano functional groups provide a rapid ion channel in the prepared electrolyte, accelerating the movement of lithium ions between MOF lattices and improving ionic conductivity. The pore size of pyridine-based MOFs is much smaller than the size of electrolyte anions, and the prepared MOF-based electrolyte can effectively prevent the passage of large-sized anions, thus providing a unique channel for lithium ion transport and promoting uniform lithium ion transport. Then, by selecting different metal compounds to prepare different metal MOFs, it was found that different metals have different atomic sizes and electron cloud densities. After complexing with ligands to form MOFs, the lattice spacing and pore size of the MOFs can be changed, resulting in different effects on lithium conduction and inhibition of anion transport. Finally, the polymerization of cyano groups in each MOF is achieved through hot pressing, thereby establishing a continuous lithium migration path and further enhancing the thermal stability and mechanical properties of the MOF electrolyte. Among them, Ni-4QBD(Li +The electrolyte prepared by this method exhibits a high conductivity of 6.12 mS / cm and low impedance at room temperature. The assembled LFP / Ni-4QBD (Li + The ) / Li battery can operate stably for over 130 cycles at a cutoff voltage as high as 4V. Therefore, the first preparation of a MOF-based all-solid-state electrolyte was achieved by screening the metal ions at the ligand center and hot-pressing them into sheets. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0026] Figure 1 Infrared test curves for different metal MOFs.

[0027] Figure 2 XRD tests for different metal MOFs.

[0028] Figure 3 SEM images and EDS elemental analysis of three metal MOFs.

[0029] Figure 4 Impedance testing of Li / Li cells assembled with different metal MOFs.

[0030] Figure 5 The values ​​represent the electrical conductivity of different metallic MOFs.

[0031] Figure 6 Electrochemical windows for different metal MOFs.

[0032] Figure 7 Thermogravimetric curves of Ni-4QBD and 4QBD are shown.

[0033] Figure 8 Ni-4QBD(Li) prepared at different hot-pressing temperatures + (Image of MOF electrolyte)

[0034] Figure 9 Ni-4QBD(Li) prepared at different hot-pressing temperatures + Electrochemical window and ionic conductivity of )-MOF electrolyte.

[0035] Figure 10 To determine the hot-pressed cyano polymerization status through semi-quantitative analysis of infrared measurements at different hot-pressing temperatures.

[0036] Figure 11Testing of Li / Li cells assembled using three metal MOFs.

[0037] Figure 12 For the assembly of LFP / Ni-4QBD(Li + Performance diagram of )-MOF / Li half-cell.

[0038] Figure 13 The lithium-ion transference number of each product in Comparative Example 2 is compared with that in Example 1.

[0039] Figure 14 The lithium-ion transference number of each product in Comparative Example 4 is compared with that in Example 1. Detailed Implementation

[0040] To make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to specific examples.

[0041] Example 1:

[0042] Preparation of Ni-4QBD-based MOF all-solid-state electrolyte and its application in batteries

[0043] 1. Weigh 0.04 mol of 4-cyanopyridine (4QBD) and 0.01 mol of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) and dissolve them in 80 ml of methanol solution, stirring for 1 h.

[0044] 2. The product after the reaction was filtered in a vacuum filtration device and washed three times with 40 ml of methanol. The powder obtained by vacuum filtration was placed in a 60°C forced-air drying oven for 12 h until the sample was dry. The dried sample was then ground into powder, collected and bottled, and named Ni-4QBD.

[0045] 3. Weigh 1g of lithium bis(trifluoromethanesulfonylimide) (LiTFSI) and 1.5g of Ni-4QBD in a glove box, dissolve them in 20ml of N-methylpyrrolidone (NMP), and stir for 48h.

[0046] 4. The reaction product was filtered using a vacuum filtration apparatus and washed three times with 20 ml of NMP. The resulting powder was then placed in a vacuum drying oven at 60°C for 12 hours until the sample was completely dry. The dried sample was then ground into powder, collected, and bottled, and named Ni-4QBD(Li + ).

[0047] 5. Weigh 0.085g Ni-4QBD(Li + The powder was evenly spread in a mold with a diameter of 15.8 mm and a height of 1 mm, and then hot-pressed at 120℃ and 45 MPa for 2 hours to obtain Ni-4QBD(Li+ MOF-based all-solid-state electrolyte.

[0048] Compare with Example 1:

[0049] Preparation of 4QBD-based MOF all-solid-state electrolytes of different metals and their applications in batteries

[0050] 1. Weigh 0.04 mol of 4-cyanopyridine (4QBD) and 0.01 mol of manganese dichloride tetrahydrate, ferrous chloride tetrahydrate, cobalt dichloride hexahydrate, copper dichloride dihydrate or zinc chloride hexahydrate, and dissolve them in 80 ml of methanol solution, stirring for 1 h.

[0051] 2. The reaction product was filtered in a vacuum filtration device and washed three times with 40 ml of methanol. The powder obtained by vacuum filtration was placed in a 60°C forced-air drying oven for 12 h until the sample was dry. The dried sample was then ground into powder, collected and bottled, and named Mn-4QBD, Fe-4QBD, Co-4QBD, Cu-4QBD and Zn-4QBD, respectively.

[0052] 3. Weigh 1g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 1.5g of Mn-4QBD, Fe-4QBD, Co-4QBD, Cu-4QBD or Zn-4QBD in a glove box, dissolve them in 20ml of N-methylpyrrolidone (NMP), and stir for 48h.

[0053] 4. The reaction product was filtered using a vacuum filtration apparatus and washed three times with 20 ml of NMP. The resulting powder was then placed in a vacuum drying oven at 60°C for 12 hours until the sample was completely dry. The dried sample was then ground into powder, collected, and bottled, and named Mn-4QBD(Li + ), Fe-4QBD(Li + ), Co-4QBD(Li + Cu-4QBD(Li) + Zn-4QBD(Li) + ).

[0054] 5. Weigh out 0.085g of Mn-4QBD(Li) + ), Fe-4QBD(Li + ), Co-4QBD(Li + Cu-4QBD(Li) + Zn-4QBD(Li) + The powder was evenly spread in a mold with a diameter of 15.8 mm and a height of 1 mm, and then hot-pressed at 120℃ and 45 MPa for 2 hours to obtain Mn-4QBD(Li+ ), Fe-4QBD(Li + ), Co-4QBD(Li + Cu-4QBD(Li) + Zn-4QBD(Li) + MOF-based all-solid-state electrolyte.

[0055] The final measured bulk impedance values ​​were 3500Ω for Mn-4QBD, 780Ω for Fe-4QBD, 1400Ω for Co-4QBD, 1700Ω for Cu-4QBD, and 3750Ω for Zn-4QBD, all significantly higher than the 370Ω of Ni-4QBD. Furthermore, the ionic conductivity tests revealed values ​​of 3.11 mS / cm for Mn-4QBD, 1.137 mS / cm for Fe-4QBD, 3.54 mS / cm for Co-4QBD, 1.95 mS / cm for Cu-4QBD, and 1.33 mS / cm for Zn-4QBD, all significantly lower than the 6.12 mS / cm of Ni-4QBD. Electrochemical window tests revealed that Mn-4QBD had a window of 3.84V, Fe-4QBD 3.99V, Co-4QBD 4.08V, Cu-4QBD 3.63V, Zn-4QBD 4.35V, and Ni-4QBD 4.13V. Subsequent battery performance tests showed that in assembled lithium-symmetric batteries, Co-4QBD exceeded the protection voltage after 22 cycles and stopped, Cu-4QBD experienced a short circuit after 124 cycles, while Ni-4QBD exhibited long-term cycling stability, remaining stable after 300 hours of cycling. Furthermore, in LFP / Li half-cell performance tests, after 130 cycles at a charging limit of 4V, the capacity retention rate reached 90%. In conclusion, the MOF electrolyte prepared with Ni-4QBD exhibited the best electrochemical performance, while the performance of other metals was relatively poor.

[0056] Compare with Example 2:

[0057] Preparation and study of MOF-based all-solid-state electrolytes with metallic Ni and different ligands.

[0058] 1. Weigh 0.04 mol of 2-cyanopyridine, 2-cyanopyrazine or 4,5-2-cyanoimidazole and 0.01 mol of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) and dissolve them in 80 ml of methanol solution, and stir for 1 h.

[0059] 2. The product after the reaction was filtered in a vacuum filtration device and washed three times with 40 ml of methanol. The powder obtained by vacuum filtration was placed in a 60°C forced-air drying oven for 12 h until the sample was dry. The dried sample was then ground into powder, collected and bottled, and named Ni-2QBD, Ni-2QBQ, and Ni-4,5-2QMZ.

[0060] 3. Weigh 1g of lithium bis(trifluoromethanesulfonylimide) (LiTFSl) and 1.5g of Ni-2QBD, Ni-2QBQ or Ni-4,5-2QMZ in a glove box, dissolve them in 20ml of N-methylpyrrolidone (NMP), and stir for 48h.

[0061] 4. The reaction product was filtered using a vacuum filtration apparatus and washed three times with 20 ml of NMP. The filtered powder was then placed in a vacuum drying oven at 60°C for 12 hours until the sample was dry. The dried sample was then ground into powder, collected, and bottled, and named Ni-2QBD(Li + Ni-2QBQ(Li) + Ni-4,5-2QMZ(Li) + ).

[0062] 5. Weigh out 0.085g of Ni-2QBD(Li) + Ni-2QBQ(Li) + Ni-4,5-2QMZ(Li) + The powder was evenly spread in a mold with a diameter of 15.8 mm and a height of 1 mm, and then hot-pressed at 120℃ and 45 MPa for 2 hours to obtain Ni-2QBD(Li) powder. + Ni-2QBQ(Li) + Ni-4,5-2QMZ(Li) + MOF-based all-solid-state electrolyte.

[0063] Subsequently, in the electrochemical performance tests, the testing methods were consistent with those shown in Comparative Example 1. In the impedance, lithium-ion conductivity, electrochemical window test, lithium symmetry, and LFP half-cell performance tests, the performance of Ni-2QBD, Ni-2QBQ, and Ni-4,5-2QMZ was significantly lower than that of Ni-4QBD in Example 1. Some experimental results are shown below. Figure 13 As shown, the lithium-ion transference numbers of their batteries are 0.1937, 0.3773 and 0.3277, respectively, all lower than the 0.637 of Ni-4QBD in Example 1.

[0064] Compare with Example 3:

[0065] An experiment on hot-pressing temperature during the preparation of Ni-4QBD-based MOF all-solid-state electrolyte.

[0066] 1. Weigh 0.04 mol of 4-cyanopyridine (4QBD) and 0.01 mol of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) and dissolve them in 80 ml of methanol solution, stirring for 1 h.

[0067] 2. The product after the reaction was filtered in a vacuum filtration device and washed three times with 40 ml of methanol. The powder obtained by vacuum filtration was placed in a 60°C forced-air drying oven for 12 h until the sample was dry. The dried sample was then ground into powder, collected and bottled, and named Ni-4QBD.

[0068] 3. Weigh 1g of lithium bis(trifluoromethanesulfonylimide) (LiTFSI) and 1.5g of Ni-4QBD in a glove box, dissolve them in 20ml of N-methylpyrrolidone (NMP), and stir for 48h.

[0069] 4. The reaction product was filtered using a vacuum filtration apparatus and washed three times with 20 ml of NMP. The resulting powder was then placed in a vacuum drying oven at 60°C for 12 hours until the sample was completely dry. The dried sample was then ground into powder, collected, and bottled, and named Ni-4QBD(Li + ).

[0070] 5. Weigh 0.085g Ni-4QBD(Li + The powder was evenly spread in a mold with a diameter of 15.8 mm and a height of 1 mm, and then hot-pressed for 2 hours at room temperature, 60℃, 120℃, 160℃, 200℃, and 45 MPa, respectively, to obtain Ni-4QBD(Li) at different hot-pressing temperatures. + MOF-based all-solid-state electrolyte.

[0071] The hot-pressing temperature of the electrolyte was determined based on the thermogravimetric analysis (TGA) curves of Ni-4QBD. Electrolytes pressed at room temperature are relatively fragile, while those pressed at 120℃ become more robust and have a smoother surface with increasing hot-pressing temperature. The electrochemical window increases from 4.13V (room-temperature pressing) to 4.43V, and the ionic conductivity increases from 6.12 mS / cm to 6.41 mS / cm. Further increases in hot-pressing temperature did not significantly alter the properties; therefore, 120℃ was ultimately selected as the optimal preparation condition.

[0072] Compare with Example 4:

[0073] Different preparation methods for Ni-4QBD-based MOF solid electrolytes.

[0074] 1. Weigh 0.04 mol of 4-cyanopyridine (4QBD) and 0.01 mol of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) and dissolve them in 80 ml of methanol solution, stirring for 1 h.

[0075] 2. The product after the reaction was filtered in a vacuum filtration device and washed three times with 40 ml of methanol. The powder obtained by vacuum filtration was placed in a 60°C forced-air drying oven for 12 h until the sample was dry. The dried sample was then ground into powder, collected and bottled, and named Ni-4QBD.

[0076] 3. Weigh 1g of lithium bis(trifluoromethanesulfonylimide) (LiTFSl) and 1.5g of Ni-4QBD in a glove box, dissolve them in 20ml of N-methylpyrrolidone (NMP), and stir for 48h.

[0077] 4. The reaction product was filtered using a vacuum filtration apparatus and washed three times with 20 ml of NMP. The resulting powder was then placed in a vacuum drying oven at 60°C for 12 hours until the sample was completely dry. The dried sample was then ground into powder, collected, and bottled, and named Ni-4QBD(Li + ).

[0078] 5. Weigh 0.1g Ni-4QBD(Li + 0.4 g of polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), or polyethylene oxide (PEO) was dissolved in 5 ml of N-methylpyrrolidone (NMP) and stirred for 24 h. The solution was then poured into a custom-made mold (70 mm long and 10 mm high, rectangular mold), and the solution was evenly spread in the mold. The molds were then dried in a 60°C oven for 24 h until completely dry, yielding electrolytes of different compositions: Ni-PVDF, Ni-PAN, or Ni-PEO.

[0079] Subsequently, in the electrochemical performance tests, the testing methods were consistent with those shown in Comparative Example 1. In the impedance, lithium-ion conductivity, electrochemical window test, lithium symmetry, and LFP half-cell performance tests, the performance of Ni-PVDF, Ni-PAN, and Ni-PEO was inferior to that of the Ni-4QBD MOF electrolyte in Example 1. Some experimental results are as follows: Figure 14 As shown, the lithium-ion transference numbers of their batteries are 0.4532, 0.268 and 0.339, respectively, all lower than the 0.637 of Ni-4QBD in Example 1.

[0080] In summary, this invention provides a MOF-based all-solid-state electrolyte prepared by hot-pressing at 120°C using Ni-4QBD as the main component. Infrared data analysis of different metal MOFs was then performed. Figure 1 (a) The overall graph shows that after metal coordination, the infrared characteristic peaks of different metal MOFs are mainly dominated by the raw material 4-cyanopyridine (4QBD). The peak position of the cyano group remains basically unchanged. Figure 1 b), while the peak of pyridine nitrogen showed a significant blue shift ( Figure 1c) This demonstrates that the coordination site of the metal is located at the pyridine nitrogen, and that the shift amplitude increases with increasing electronegativity of the metal, which also indirectly proves the successful preparation of different metal MOFs. After inferring the coordination site using infrared spectroscopy, the expected structure of the metal MOF was constructed using MS, and the XRD patterns of the MOF were obtained by simulation using Mercury software. The XRD diffraction peak positions of different metal M-MOF powders were basically consistent with the simulated peak positions. Figure 2 Furthermore, the lattice spacing of the 120-plane was calculated using the Bragg equation, showing a trend consistent with the theoretical ionic radius (Table 1), which also demonstrates the successful preparation of different metal MOFs. Three metal MOFs were selected here: Co-4QBD (…). Figure 3 a), Ni-4QBD Figure 3 b), Cu-4QBD( Figure 3 c) SEM morphology analysis revealed that different metal MOFs exhibited different morphological characteristics. Furthermore, EDS elemental analysis of selected locations clearly showed the distribution of the corresponding metals. Therefore, based on the above three test results, the successful preparation of different metal MOFs can be inferred.

[0081] The electrochemical performance of different metal MOF electrolytes was then tested. First, Li / Li batteries were assembled, and the impedance of different electrolytes was measured. Figure 4 It can be observed that Ni-MOF has the lowest impedance, approximately 370Ω, which is close to that of typical composite electrolytes and nearly an order of magnitude lower than other metal MOFs. Furthermore, during the testing of ion conductivity... Figure 5 Through temperature-dependent impedance spectroscopy, it was found that Ni-MOF has the lowest activation energy, resulting in less energy required for lithium-ion transitions. Consequently, its conductivity is as high as 6.12 mS / cm, nearly an order of magnitude higher than other electrolytes. Finally, the electrochemical stability of the electrolyte was tested... Figure 6 Furthermore, Ni-MOF also exhibits the second-widest electrochemical window (LSV), reaching 4.13V. In summary, based on fundamental electrochemical performance tests such as impedance, ionic conductivity, and LSV, it is evident that Ni-MOF possesses the best electrochemical performance. Therefore, all subsequent half-cell performance tests were conducted using Ni-MOF.

[0082] MOFs prepared by thermogravimetric analysis of ligand raw material 4QBD and metal coordination were subjected to thermogravimetric analysis. Figure 7 Tests revealed that the thermal stability of the MOF formed after coordination was significantly improved, demonstrating the high safety and stability of MOF materials. Furthermore, it was found that the electrolyte sheet formed by high-temperature pressing was more robust than that formed by room-temperature pressing of MOF electrolytes. Figure 8The surface is also smoother, and its electrochemical window has increased from 4.13V (at room temperature) to 4.43V. Figure 9 a) The ionic conductivity also increased from 6.12 mS / cm to 6.41 mS / cm. Figure 9 b). Subsequently, semi-quantitative analysis was performed using infrared data from different hot-pressing temperatures, comparing the peak area ratios of cyano groups and other functional groups in the infrared spectrum. Figure 10 a) It was found that as the hot-pressing temperature increased, the area ratio of the cyano group to other peaks gradually decreased. Figure 10 b) demonstrates that high temperatures can indeed initiate cyano polymerization, thereby improving the thermal stability and mechanical properties of the electrolyte. Therefore, subsequent electrolytes were all prepared and used after hot pressing at 120°C.

[0083] Correspondingly, Ni-MOF cells also exhibit the best performance. In Li / Li symmetric cell tests ( Figure 11 Ni-MOF can operate stably for over 300 hours, while other MOFs exhibit relatively poor performance, showing significant short-circuit and over-protection voltage phenomena. Finally, the performance of LFP / Li half-cells assembled with Ni-MOF electrolyte was tested. Figure 12 a) After 130 cycles of stable operation at a charging voltage limit of 4V, the capacity retention rate can reach 90%. Figure 12 b) The performance is higher than that of most all-solid-state electrolytes reported in the current literature.

[0084] Table 1 shows the lattice spacing of different metal MOFs calculated by XRD.

[0085]

[0086] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a MOF-based all-solid-state electrolyte, characterized in that: include, (1) Dissolve 4-cyanopyridine and nickel salt in a solvent and mix them; (2) The product obtained in step (1) is filtered, washed, dried and ground into powder to obtain Ni-4QBD; (3) Dissolve lithium bis(trifluoromethanesulfonylimide) and Ni-4QBD in a solvent and mix them; (4) The product obtained in step (3) is filtered, washed, dried, and ground into powder to obtain Ni-4QBD(Li + ); (5) Ni-4QBD(Li + The mixture is evenly spread in a mold and hot-pressed to obtain a MOF-based all-solid electrolyte.

2. The method for preparing MOF-based all-solid-state electrolyte according to claim 1, characterized in that: In step (1), the nickel salt includes nickel nitrate, and the molar ratio of 4-cyanopyridine to the nickel salt is 4:

1.

3. The method for preparing MOF-based all-solid-state electrolyte according to claim 1 or 2, characterized in that: In step (1), the solvent includes methanol, and the concentration of 4-cyanopyridine is 0.5-1M; the mixing includes stirring and mixing for 1-2 hours.

4. The method for preparing the MOF-based all-solid-state electrolyte according to claim 1 or 2, characterized in that: In step (2), the drying includes drying the sample at 50-60°C.

5. The method for preparing the MOF-based all-solid-state electrolyte according to claim 1 or 2, characterized in that: In step (3), the mass ratio of lithium bis(trifluoromethanesulfonylimide) to Ni-4QBD is 1:1.

5.

6. The method for preparing the MOF-based all-solid-state electrolyte according to claim 1 or 2, characterized in that: In step (3), the solvent includes N-methylpyrrolidone; the mixing includes stirring for 48 to 72 hours; and the concentration of lithium bis(trifluoromethanesulfonyl)imide is 5 to 10%.

7. The method for preparing the MOF-based all-solid-state electrolyte according to claim 1 or 2, characterized in that: In step (4), the drying includes drying the sample at 50-60°C.

8. The method for preparing the MOF-based all-solid-state electrolyte according to claim 1 or 2, characterized in that: In step (5), the hot pressing includes hot pressing for 2 to 3 hours at 100 to 120°C and 45 to 50 MPa.

9. The application of the MOF-based all-solid-state electrolyte prepared by the method of claim 1 in batteries.

10. The application according to claim 9, characterized in that: The battery includes a lithium battery.

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