In-situ solid-state metal-organic framework-based solid electrolyte and its preparation method and application

Abstract

The present invention belongs to the field of sodium metal batteries, and relates to the preparation of an in-situ solid-state metal-organic framework-based solid electrolyte and its application in sodium metal batteries. In this application, the sulfonic acid functionalized metal-organic framework material is first formed into a flexible film of a certain thickness by a rolling method, and a precursor solution containing a plastic crystal electrolyte and polyethylene glycol diacrylate is injected, and finally an in-situ solid-state metal-organic framework-based solid electrolyte is obtained after several hours at a certain temperature. The plastic crystal electrolyte can transport sodium ions faster and has a higher ionic conductivity. The in-situ solidification of polyethylene glycol diacrylate promotes the construction of a uniform and stable interface between the electrolyte / electrode, thereby successfully suppressing the interfacial side reactions. The solid electrolyte of the present invention not only has a higher ionic conductivity, but also has better interface stability, thereby optimizing the electrochemical performance of the solid-state sodium metal battery and achieving high performance of the solid-state sodium metal battery.

Description

Technical Field

[0001] The present invention belongs to the field of sodium metal batteries and relates to the preparation of an in-situ solid-state metal-organic framework-based solid electrolyte and its application in sodium metal batteries. Background Art

[0002] With the growing demand for portable electronic devices and electric vehicles in modern society, people are also demanding high-performance energy storage devices. Lithium metal batteries have the highest energy density among secondary batteries, but the abundance of lithium and transition metals such as cobalt in the positive electrode is limited. Sodium metal batteries have similar chemical properties to lithium metal batteries, and sodium resources are abundant and low-cost, making them a hot topic of research. However, the sodium metal batteries reported so far usually use organic electrolytes, which are prone to leakage, flatulence, and even fire or explosion. Compared with liquid electrolytes, solid electrolytes can effectively avoid problems such as leakage and internal short circuits in the battery, and are a highly safe electrolyte system. Therefore, constructing solid-state sodium metal batteries is an important way to solve safety issues.

[0003] As an important component of solid-state energy storage devices, solid electrolytes are widely used in many battery systems such as lithium-ion batteries, sodium-ion batteries, and lithium-sulfur batteries. However, low ionic conductivity and poor interfacial compatibility remain the two main factors limiting the application of solid electrolytes. Inorganic solid electrolytes such as Li 10 GeP2S 12 ( Advanced Materials , 2022,9, 2200822) exhibits extremely high ionic conductivity (typically 10 -2 S cm -1 Order of magnitude). However, the interfacial stability between inorganic solid electrolytes and electrodes is poor. Compared with inorganic solid electrolytes, polymer electrolytes have greater advantages in building a tight interface, low cost and good flexibility. In situ solid-state technology is a simple and efficient synthesis strategy for polymer electrolytes. Specifically, a precursor solution formed by monomers, initiators and liquid electrolytes is injected into the battery and fills all the pores in the electrode. After heating and polymerization, a tight interface is formed between the electrode and the electrolyte. Poly (ethylene glycol) diacrylate-based (PEGDA) monomers are inexpensive and the in situ curing technology is simple. Therefore, PEGDA has become a good choice for achieving in situ solidification of polymers. However, in current research reports, the cations and anions in the in situ solidified PEGDA-based polymer electrolytes have a greater coordination effect with the polymer matrix, which results in the electrolyte having a lower ion migration number ( Energy Environmental Materials , doi:10.1002 / eem2.12447;CN111554974 A). Therefore, it is imperative to improve the migration number of PEGDA-based polymer electrolytes.

[0004] Metal-organic framework materials (MOFs) are organic-inorganic hybrid materials formed by metal ions and organic ligands through coordination bonds. MOFs materials have abundant metal sites and organic functional groups and are used in many fields such as gas separation, chemical catalysis, and drug delivery. At the same time, due to their special structure, MOFs materials have gradually played an important role in the field of solid-state electrolytes and have been used in battery systems such as lithium-ion batteries and lithium-sulfur batteries. Given the diversity and adjustability of the pore structure of MOFs materials, MOF-based electrolytes can provide a unique channel for ion transport for cations, thereby promoting the uniform transport and distribution of cations ( Energy Storage Materials , 2022, 47, 262). Therefore, the composite of MOFs and polymers is beneficial for improving the ionic conductivity of polymer electrolytes. Patent CN 112670565 A prepares a high-surface-area MOF-based composite gel solid electrolyte containing amino groups to improve the ionic conductivity of polymer electrolytes. However, this patent does not address the poor compatibility between MOF electrolytes and electrodes. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention proposes a preparation method of an in-situ solid-state metal-organic framework-based solid electrolyte and its application in sodium metal batteries.

[0006] The technical solution of the present invention is achieved as follows:

[0007] A method for preparing an in-situ solid-state metal-organic framework-based solid electrolyte, comprising the following steps:

[0008] (1) Preparation of MOF matrix membrane: Dissolve ZrCl4 in N,N-dimethylformamide (DMF) containing acetic acid and stir thoroughly to obtain solution A. Dissolve 2-sulfonatoterephthalate monosodium salt in concentrated hydrochloric acid and stir to obtain solution B. Then, mix solutions A and B, stir for 15 minutes, and place in a 120°C reactor. After 24 hours, remove the mixture and centrifuge to dry it to obtain the sulfonic acid functionalized MOF material, which is then thoroughly mixed with PTFE, rolled into a membrane, and made into a disc with a diameter of 16 mm.

[0009] (2) Prepare the precursor solution: heat and dissolve PEGDA, and add succinonitrile, sodium salt and fluoroethylene carbonate in sequence. After heating and stirring for 1 hour, add a certain amount of azobisisobutyronitrile and stir thoroughly.

[0010] (3) Preparation of in-situ solid-state MOF-based electrolyte: The precursor solution of step (2) is injected into the wafer of step (1), and the wafer is allowed to stand in an oven for several hours to obtain an in-situ solid-state metal-organic framework-based solid electrolyte.

[0011] Furthermore, in step (1), the molar ratio of zirconium chloride to monosodium 2-sulfonate terephthalate is 1:(0.5-2), the molar ratio of zirconium chloride to acetic acid is 1:(10-50), and the molar ratio of monosodium 2-sulfonate terephthalate to concentrated hydrochloric acid is 1:(0.1-2).

[0012] Furthermore, the molar ratio of the sulfonic acid functionalized MOF material to PTFE is (6-9):1, the diameter of the disc is 16 mm, and the thickness is 50-150 μm.

[0013] The S=O bonds of the sulfonic acid-functionalized MOFs and the oxygen-containing functional groups of PEGDA interact with sodium ions, and these two interactions compete with each other, promoting rapid sodium ion transport. Succinonitrile has a large dielectric constant, which promotes the dissociation of sodium salts. Therefore, the mixture of succinonitrile and sodium salts has high ionic conductivity. Furthermore, the in situ polymerization of polyethylene glycol diacrylate promotes good interfacial compatibility between the electrode and the electrolyte.

[0014] Furthermore, the sodium salt in step (2) is one or more of sodium bis(trifluoromethanesulfonyl)imide, sodium perchlorate, sodium hexafluorophosphate, sodium bis(fluorosulfonyl)imide or sodium tetrafluoroborate.

[0015] Furthermore, the weight ratio of polyethylene glycol diacrylate, succinonitrile and azobisisobutyronitrile is 100:(10~70):(0.1~1); the molar ratio of succinonitrile and sodium salt is 1:(10~30), and the added mass percentage of fluoroethylene carbonate in the precursor solution is 2~10 wt%.

[0016] The in-situ solid-state metal-organic framework-based solid electrolyte prepared by the above method is in a quasi-solid state at room temperature.

[0017] The sodium metal battery containing the above-mentioned in-situ solid-state metal-organic framework-based solid electrolyte has a capacity retention rate of 97.3% after 100 charge and discharge cycles.

[0018] The preparation method of the above-mentioned sodium metal battery comprises the following steps: placing the positive electrode sheet, the disc obtained in step (1) and the negative electrode sheet into the battery in layers in sequence, injecting the precursor solution, packaging the battery and placing the battery in an oven, and allowing the battery to stand to obtain the sodium metal battery.

[0019] Furthermore, the active material of the positive electrode sheet is one or more of Prussian blue, transition oxides, polyanions, sulfur and sulfided polyacrylonitrile; the negative electrode sheet is a sodium sheet; and the sodium metal battery is a button cell or a soft pack cell.

[0020] Preferably, the oven temperature is 50-80° C., and the standing time is 1-12 h.

[0021] The present invention has the following beneficial effects:

[0022] 1. The pore size of the sulfonic acid functionalized MOFs (UiO-66-SO3H) used in the present invention is 12 Å, which is slightly larger than the size of the electrolyte anion. Therefore, based on the steric effect, the MOFs used in the present invention can use the pore structure to restrict the movement of the electrolyte anion, allowing only the rapid migration of sodium ions. At the same time, as shown in the attached Figure 1 As shown, the UiO-66-SO3H material has abundant sulfonic acid functional groups, and the S=O bonds on the sulfonic acid functional groups have a strong interaction with sodium ions. Given that the oxygen-containing functional groups in the PEGDA-based polymer also have a strong interaction with sodium ions, the UiO-66-SO3H material and the PEGDA-based polymer both interact with sodium ions, and these two interactions compete, thereby promoting the rapid transport of sodium ions and increasing the migration number of the PEGDA-based polymer electrolyte. In addition, succinonitrile can dissociate sodium salts and has a higher ionic conductivity when combined with sodium salts. The in-situ solid-state metal-organic framework-based solid electrolyte prepared by the present invention can not only promote the uniform distribution of sodium ions, but also promote the rapid transport of sodium ions. Therefore, the solid electrolyte of the present invention has a higher ionic conductivity.

[0023] 2. The in-situ solid-state technology selected by the present invention is a simple and efficient synthesis strategy for polymer electrolytes. Specifically, a precursor solution formed by PEGDA monomer, initiator and plastic crystal electrolyte is injected into the battery and fills all the pores in the electrode. After the PEGDA monomer is heated and polymerized, a tight interface is formed between the electrode and the electrolyte. This in-situ solid-state technology not only effectively avoids the problem of large interfacial gaps between MOFs particles, but also promotes good interfacial stability between the electrode and the electrolyte. In addition, PEGDA monomer is inexpensive, the in-situ curing technology is simple, and it is compatible with existing battery manufacturing processes. In combination with the existing technical problems, this application uses MOFs material as a matrix, forms a MOF matrix membrane by rolling, and utilizes the pore structure of the MOFs material to provide a unique channel for ion transmission for sodium ions. The MOF matrix membrane is compounded with PEGDA using in-situ solid-state technology, and a MOF-based solid electrolyte with high ionic conductivity and good interface compatibility is achieved through bonding with sodium ions.

[0024] 3. The in-situ solid-state metal-organic framework-based solid electrolyte prepared in this application exhibits a quasi-solid state at room temperature. Therefore, sodium metal batteries using the solid-state electrolyte of the present invention can effectively avoid problems such as internal short circuits in the battery and electrolyte leakage, thereby significantly improving the safety of sodium metal batteries. In addition, given that the in-situ solid-state metal-organic framework-based solid electrolyte of the present invention has high ionic conductivity, sodium metal batteries using this electrolyte have good electrochemical performance. The preparation method of the present invention is simple and easy to implement and can be used to achieve industrial-grade manufacturing of high-energy-density solid-state batteries with excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 Schematic diagram of the sodium ion transport mechanism in the electrolyte of the present invention.

[0027] Figure 2 Digital photograph of the precursor solution in Example 3 after 12 h of storage.

[0028] Figure 3 This is a digital photo of the MOF matrix film in Example 3.

[0029] Figure 4 These are the conductivity test diagrams for the control example, reference example, and embodiment 3.

[0030] Figure 5 The sodium symmetric battery of the control example, reference example and embodiment 3 is 0.1 mA cm -2 Cycle diagram under current density.

[0031] Figure 6 The sodium metal batteries of the control example, reference example and embodiment 3 were tested at 0.1 C (1C = 118 mA g -1 ) cycle diagram under .

[0032] Figure 7 Graph showing the rate performance of the sodium metal batteries of the control example, reference example, and embodiment 3. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example 1

[0035] The preparation method of the in-situ solid-state metal-organic framework-based solid electrolyte of this embodiment comprises the following steps:

[0036] (1) Preparation of MOF matrix membrane: 0.29 g (1 mmol) ZrCl4 was dissolved in 15 mL DMF, stirred, and then 570 μL (10 mmol) acetic acid was added. After thorough stirring, the resulting solution was solution A. 0.165 g (0.5 mmol) monosodium 2-sulfonate terephthalate was dissolved in 20 μL (0.1 mmol) concentrated hydrochloric acid and stirred to obtain solution B. Then, solutions A and B were mixed, stirred for 15 minutes, and placed in a 120 °C reactor. After 24 hours, the mixture was taken out and centrifuged and dried to obtain UiO-66-SO3H material, which was then thoroughly mixed with PTFE at a molar ratio of 6:1, rolled into a membrane, and made into a disc with a diameter of 16 mm and a thickness of 50 μm;

[0037] (2) Preparation of precursor solution: Heat and dissolve PEGDA, and add 10 wt% succinonitrile, sodium perchlorate and 2 wt% fluoroethylene carbonate in sequence, wherein the molar ratio of succinonitrile to sodium perchlorate is 10:1. After heating and stirring for 1 hour, add a certain amount of azobisisobutyronitrile and stir thoroughly (the weight ratio of PEGDA to azobisisobutyronitrile is 100:0.1);

[0038] (3) Preparation of in-situ solid-state MOF-based electrolyte and all-solid-state sodium metal battery: The precursor solution of step (2) was injected into the wafer of step (1), and the wafer was allowed to stand in an oven at 50°C for 1 hour to obtain the in-situ solid-state MOF-based electrolyte.

[0039] Example 2

[0040] (1) Preparation of MOF matrix membrane: 0.29 g (1 mmol) ZrCl4 was dissolved in 15 mL DMF, stirred, and then 1.4 mL (20 mmol) acetic acid was added. After thorough stirring, the solution was obtained as solution A. 0.33 g (1 mmol) monosodium 2-sulfonate terephthalate was dissolved in 0.1 mL (0.5 mmol) concentrated hydrochloric acid, and stirred to obtain solution B. Then, solutions A and B were mixed, stirred for 15 minutes, and placed in a 120 °C reactor. After 24 hours, the mixture was taken out and centrifuged and dried to obtain UiO-66-SO3H material, which was then thoroughly mixed with PTFE at a molar ratio of 8:1, rolled into a membrane, and made into a disc with a diameter of 16 mm and a thickness of 50 μm;

[0041] (2) Preparation of precursor solution: Heat and dissolve PEGDA, and add 50 wt% succinonitrile, sodium perchlorate and 5 wt% fluoroethylene carbonate in sequence, where the molar ratio of succinonitrile to sodium perchlorate is 20:1. After heating and stirring for 1 hour, add a certain amount of azobisisobutyronitrile and stir thoroughly (the weight ratio of PEGDA to azobisisobutyronitrile is 100:0.2).

[0042] (3) Preparation of in-situ solid-state MOF-based electrolyte and all-solid-state sodium metal battery: The precursor solution of step (2) was injected into the wafer of step (1), and the wafer was allowed to stand in an oven at 60°C for 1 hour to obtain the in-situ solid-state MOF-based electrolyte.

[0043] Example 3

[0044] The preparation method of the in-situ solid-state metal-organic framework-based solid electrolyte of this embodiment comprises the following steps:

[0045] (1) Preparation of MOF matrix membrane: 0.29 g (1 mmol) ZrCl4 was dissolved in 15 mL DMF, stirred, and then 2.1 mL (37 mmol) acetic acid was added. After thorough stirring, the resulting solution was solution A. 0.33 g (1 mmol) monosodium 2-sulfonate terephthalate was dissolved in 0.2 mL (1 mmol) concentrated hydrochloric acid and stirred to obtain solution B. Then, solutions A and B were mixed, stirred for 15 minutes, and placed in a 120 °C reactor. After 24 hours, the mixture was taken out and centrifuged and dried to obtain UiO-66-SO3H material, which was then thoroughly mixed with PTFE at a molar ratio of 9:1, rolled into a membrane, and made into a disc with a diameter of 16 mm and a thickness of 100 μm;

[0046] (2) Preparation of precursor solution: Heat and dissolve PEGDA, and add 60 wt% succinonitrile, sodium perchlorate and 5 wt% fluoroethylene carbonate in sequence, where the molar ratio of succinonitrile to sodium perchlorate is 20:1. After heating and stirring for 1 hour, add a certain amount of azobisisobutyronitrile and stir thoroughly (the weight ratio of PEGDA to azobisisobutyronitrile is 100:0.1).

[0047] (3) Preparation of in-situ solid-state MOF-based electrolyte and all-solid-state sodium metal battery: The precursor solution of step (2) was injected into the wafer of step (1), and the wafer was allowed to stand in an oven at 60 °C for 4 hours to obtain the in-situ solid-state MOF-based electrolyte.

[0048] in, Figure 2 This is the precursor solution of Example 3. As can be seen from the figure, the precursor solution becomes solid after standing for 24 hours, so the prepared metal organic framework-based electrolyte is a solid electrolyte. Figure 3 This is a digital photo of the MOF matrix membrane. Figure 3 It can be seen that the film prepared in this application has good flexibility.

[0049] Example 4

[0050] The preparation method of the in-situ solid-state metal-organic framework-based solid electrolyte of this embodiment has the same steps as those of Example 3, except that step (2) is changed to: preparing a precursor solution: heating and dissolving PEGDA, and sequentially adding 70 wt % of succinonitrile, sodium perchlorate and 5 wt % of fluoroethylene carbonate, wherein the molar ratio of succinonitrile to sodium perchlorate is 20:1, and then adding a certain amount of azobisisobutyronitrile after heating and stirring for 1 hour and stirring thoroughly (the weight ratio of PEGDA to azobisisobutyronitrile is 100:0.1).

[0051] Example 5

[0052] The preparation method of the in-situ solid-state metal-organic framework-based solid electrolyte of this embodiment has the same steps as those of Example 3, except that step (2) is changed to: preparing a precursor solution: heating and dissolving PEGDA, and sequentially adding 60 wt % of succinonitrile, sodium hexafluorophosphate and 5 wt % of fluoroethylene carbonate, wherein the molar ratio of succinonitrile to sodium hexafluorophosphate is 20:1, and then adding a certain amount of azobisisobutyronitrile after heating and stirring for 1 hour and stirring thoroughly (the weight ratio of PEGDA to azobisisobutyronitrile is 100:0.1).

[0053] Example 6

[0054] The preparation method of the in-situ solid-state metal-organic framework-based solid electrolyte of this embodiment comprises the following steps:

[0055] (1) Preparation of MOF matrix membrane: 0.29 g (1 mmol) ZrCl4 was dissolved in 15 mL DMF, stirred, and then 2.6 mL (45 mmol) acetic acid was added. After thorough stirring, the solution was obtained as solution A. 0.66 g (2 mmol) monosodium 2-sulfonate terephthalate was dissolved in 0.3 mL (1.5 mmol) concentrated hydrochloric acid and stirred to obtain solution B. Then, solutions A and B were mixed, stirred for 15 minutes, and placed in a 120 °C reactor. After 24 hours, the mixture was taken out and centrifuged and dried to obtain UiO-66-SO3H material, which was then thoroughly mixed with PTFE at a molar ratio of 9:1, rolled into a membrane, and made into a disc with a diameter of 16 mm and a thickness of 150 μm;

[0056] (2) Preparation of precursor solution: Heat and dissolve PEGDA, and add 10 wt% succinonitrile, sodium perchlorate and 7 wt% fluoroethylene carbonate in sequence, wherein the molar ratio of succinonitrile to sodium perchlorate is 25:1. After heating and stirring for 1 hour, add a certain amount of azobisisobutyronitrile and stir thoroughly (the weight ratio of PEGDA to azobisisobutyronitrile is 100:0.8);

[0057] (3) Preparation of in-situ solid-state MOF-based electrolyte and all-solid-state sodium metal battery: The precursor solution of step (2) was injected into the wafer of step (1), and the wafer was allowed to stand in an oven at 70 °C for 4 hours to obtain the in-situ solid-state MOF-based electrolyte.

[0058] Example 7

[0059] The preparation method of the in-situ solid-state metal-organic framework-based solid electrolyte of this embodiment comprises the following steps:

[0060] (1) Preparation of MOF matrix membrane: 0.29 g (1 mmol) ZrCl4 was dissolved in 15 mL DMF, stirred, and then 2.9 mL (50 mmol) acetic acid was added. After thorough stirring, the solution was obtained as solution A. 0.66 g (2 mmol) monosodium 2-sulfonate terephthalate was dissolved in 0.4 mL (2 mmol) concentrated hydrochloric acid and stirred to obtain solution B. Then, solutions A and B were mixed, stirred for 15 minutes, and placed in a 120 °C reactor. After 24 hours, the mixture was taken out and centrifuged and dried to obtain UiO-66-SO3H material, which was then thoroughly mixed with PTFE at a molar ratio of 9:1, rolled into a membrane, and made into a disc with a diameter of 16 mm and a thickness of 150 μm;

[0061] (2) Preparation of precursor solution: Heat and dissolve PEGDA, and add 60 wt% succinonitrile, sodium perchlorate and 10 wt% fluoroethylene carbonate in sequence, wherein the molar ratio of succinonitrile to sodium perchlorate is 30:1. After heating and stirring for 1 hour, add a certain amount of azobisisobutyronitrile and stir thoroughly (the weight ratio of PEGDA to azobisisobutyronitrile is 100:1);

[0062] (3) Preparation of in-situ solid-state MOF-based electrolyte and all-solid-state sodium metal battery: The precursor solution of step (2) was injected into the wafer of step (1), and the wafer was allowed to stand in an oven at 80°C for 4 hours to obtain the in-situ solid-state MOF-based electrolyte.

[0063] Control Example

[0064] In a glove box, Na3V2(PO4)3 was used as the positive electrode material, metallic sodium was used as the negative electrode, a glass fiber separator was placed between the positive and negative electrodes, and the same precursor solution as in Example 3 was added dropwise to assemble a button battery.

[0065] Reference example

[0066] The steps were the same as those in the control example, except that the precursor solution preparation was changed to: PEGDA was heated to dissolve, and 60 wt% of succinonitrile and sodium perchlorate were added in sequence, wherein the molar ratio of succinonitrile to sodium perchlorate was 20:1. After heating and stirring for 1 hour, a certain amount of azobisisobutyronitrile was added and stirred thoroughly (the weight ratio of PEGDA to azobisisobutyronitrile was 100:0.1).

[0067] Implementation effect examples

[0068] The Na3V2(PO4)3 positive electrode sheet, the disc prepared in step (1) in Example 3, and the sodium metal negative electrode sheet were sequentially layered and placed in a 2032-type button battery, and the precursor solution in step (2) in Example 3 was injected. After the battery was packaged, it was placed in a 60°C oven and allowed to stand for 4 hours to obtain a solid-state sodium metal battery. The electrochemical test was carried out with the button batteries prepared in the reference example and the control example.

[0069] Test method:

[0070] (1) Conductivity test

[0071] The electrolytes in the control example, reference example, and Example 3 were placed between two stainless steel sheets and assembled into button cells. AC impedance tests were performed under the conditions of a voltage amplitude of 5 mV and a frequency range of 100 mHz-100 kHz. The test results are shown in Tables 1 and Figure 2 The following formula is used to calculate the ionic conductivity of all electrolytes: σ = d / (RS), where d is the thickness of the substrate film, R is the intrinsic impedance of the electrolyte, and S is the effective area of ​​the electrolyte.

[0072] Table 1 shows the conductivity of the control example, reference example and embodiment 3

[0073]

[0074] like Figure 4As shown, compared to the control and reference examples, the electrolyte of Example 3 has the smallest intrinsic impedance (R). The ionic conductivity was calculated according to the formula, and the results are shown in Table 1. The solid electrolyte of Example 3 has the highest ionic conductivity, reaching 4.27 mS / cm. This is due, on the one hand, to the interaction between the S=O bonds of the sulfonic acid-functionalized MOFs and the oxygen-containing functional groups of PEGDA with sodium ions, and these two interactions compete, thereby promoting rapid sodium ion transport. It is also due to the high ionic conductivity of the mixture of succinonitrile and sodium salt.

[0075] (2) Sodium symmetric battery cycle test

[0076] The electrolytes in the control example, reference example and Example 3 were placed between two stainless steel sheets and assembled into button cells, which were placed in a 60 °C oven for 4 h. -2 The sodium deposition / dissolution process is carried out at a current density of Figure 5 It can be seen that the voltage of the sodium symmetric battery of the reference example fluctuates greatly during the entire cycle, and the corresponding voltage difference increases from 1.91 V at the beginning to more than 4 V. This shows that the interface stability between the electrolyte and sodium of the reference example is poor. -2 At a current density of 1.5 volts, the sodium symmetric battery in the control example was relatively stable, with an overvoltage of 0.737 V. However, the sodium symmetric battery in Example 3 maintained stable voltage fluctuations throughout the entire cycle, with an overvoltage maintained at approximately 0.246 V, and no short circuiting occurred. This demonstrates the improved stability of the electrolyte and sodium in Example 3.

[0077] (3) Battery cycle performance test

[0078] All the above batteries were placed in 0.1 C (1C=118 mAh / g) and 2.3-3.9 V voltage range for charge and discharge cycle test. Figure 6 As can be seen, the sodium metal battery in Example 3 maintained a capacity of 97.3% after 100 charge-discharge cycles, while the reference battery could only maintain 10 cycles. This demonstrates that batteries using in-situ solid-state MOF-based electrolytes have excellent cycling performance.

[0079] (4) Battery rate performance test

[0080] The above button battery was subjected to charge and discharge cycle test at different rates. Figure 7 It can be seen that the sodium metal battery of Example 3 has excellent rate performance. At a rate of 1 C, the discharge specific capacity of Example 3 reaches 62.7 mAh / g, while the reference example cannot be charged and discharged normally at a high rate.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing an in-situ solid-state metal-organic framework-based solid electrolyte, characterized in that: Here are the steps: (1) A zirconium chloride solution containing acetic acid is fully mixed with a concentrated hydrochloric acid solution of monosodium 2-sulfonate terephthalate. After the reaction is complete, the mixture is centrifuged and dried to obtain a sulfonic acid functionalized MOF material. The material is fully mixed with PTFE and rolled into a film and then made into a disc. (2) After polyethylene glycol diacrylate is heated and dissolved, succinonitrile, sodium salt and fluoroethylene carbonate are added in sequence, and after heating and stirring, azobisisobutyronitrile is added and stirred to obtain a precursor solution; (3) Injecting the precursor solution of step (2) into the wafer of step (1), and heating to obtain an in-situ solid-state metal-organic framework-based solid electrolyte.

2. The method for preparing an in-situ solid-state metal-organic framework-based solid electrolyte according to claim 1, wherein: In the step (1), the molar ratio of zirconium chloride to monosodium 2-sulfonate terephthalate is 1:(0.5-2), the molar ratio of zirconium chloride to acetic acid is 1:(10-50), and the molar ratio of monosodium 2-sulfonate terephthalate to concentrated hydrochloric acid is 1:(0.1-2).

3. The method for preparing an in-situ solid-state metal-organic framework-based solid electrolyte according to claim 2, wherein: The molar ratio of the sulfonic acid functionalized MOF material to PTFE is (6-9):1, the diameter of the disc is 16 mm, and the thickness is 50-150 μm.

4. The method for preparing an in-situ solid-state metal-organic framework-based solid electrolyte according to claim 3, wherein: The sodium salt in step (2) is one or more of sodium bis(trifluoromethanesulfonyl)imide, sodium perchlorate, sodium hexafluorophosphate, sodium bis(fluorosulfonyl)imide or sodium tetrafluoroborate.

5. The method for preparing an in-situ solid-state metal-organic framework-based solid electrolyte according to claim 4, wherein: The weight ratio of polyethylene glycol diacrylate, succinonitrile and azobisisobutyronitrile is 100:(10-70):(0.1-1); the molar ratio of succinonitrile and sodium salt is 1:(10-30), and the added mass percentage of fluoroethylene carbonate in the precursor solution is 2-10 wt%.

6. An in-situ solid-state metal-organic framework-based solid electrolyte prepared by the method according to any one of claims 1 to 5, characterized in that: The in-situ solid-state metal-organic framework-based solid electrolyte presents a quasi-solid state at room temperature.

7. A sodium metal battery comprising the in-situ solid-state metal-organic framework-based solid electrolyte according to claim 6.

8. The method for preparing a sodium metal battery according to claim 7, characterized in that: The steps are as follows: the positive electrode sheet, the disc in step (1) and the negative electrode sheet are sequentially layered into the battery, and the precursor solution is injected. After packaging, the battery is placed in an oven and allowed to stand to obtain a sodium metal battery.

9. The method for preparing a sodium metal battery according to claim 8, wherein: The active material of the positive electrode sheet is one or more of Prussian blue, transition oxides, polyanions, sulfur and sulfurized polyacrylonitrile; the negative electrode sheet is a sodium sheet; and the sodium metal battery is a button cell or a soft pack cell.

10. The preparation method according to claim 9, wherein: The oven temperature is 50-80° C., and the standing time is 1-12 h.

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