A high-voltage all-ether gel electrolyte, its preparation method and application in quasi-solid-state sodium-ion batteries

Abstract

The present invention discloses a high-voltage all-ether gel electrolyte, a preparation method thereof, and an application thereof in a quasi-solid-state sodium ion battery, and belongs to the field of new energy technology. The preparation method is as follows: first, dissolving a sodium salt in an ether organic solvent to obtain an electrolyte; second, adding a polymerization monomer to the electrolyte and stirring it fully to obtain a precursor solution; finally, adding an initiator to the precursor solution and stirring it fully to initiate a self-polymerization reaction to obtain the high-voltage all-ether gel electrolyte. The high-voltage all-ether gel electrolyte prepared by the present invention also has high ionic conductivity and high antioxidant capacity, and can be used to prepare high-voltage, high-rate quasi-solid-state sodium ion batteries. In addition, the method of the present invention has low cost, simple process, convenient operation, and is easy to realize commercial production.

Description

Technical Field

[0001] The invention belongs to the technical field of new energy, and in particular relates to a high-voltage all-ether gel electrolyte and a preparation method thereof, and an application thereof in a quasi-solid-state sodium ion battery. Background Art

[0002] In recent years, with the development of new energy industry and the rising demand of electric vehicle market, the low abundance of lithium resources in the earth's crust and the uneven regional distribution have made people seek energy storage systems other than lithium-ion batteries. Because sodium-ion batteries have a similar "rocking chair" principle to lithium-ion batteries, they are low-cost, long-life, and suitable for large-scale energy storage. They are considered to be a promising energy storage supplement system for lithium-ion batteries. Electrolytes have the functions of isolating positive and negative electrode materials and providing alkali metal ion transmission as a carrier, which plays a key role in the electrochemical performance of sodium-ion batteries. Ether electrolytes have the characteristics of low viscosity and high ionic conductivity. Compared with ester electrolytes, they have good interface compatibility with negative electrodes such as sodium metal and carbon materials during charging and discharging. They have lower interface resistance and thinner solid electrolyte interface, which can further improve the rate performance of sodium-ion batteries. However, the higher highest occupied molecular orbital energy level (HOMO) of ether electrolytes makes their inherent antioxidant properties insufficient. When the battery voltage exceeds 4.0V (vs.Na + / Na), violent oxidative decomposition will occur, making it difficult to form a stable cathode / electrolyte interface (CEI), resulting in severe irreversible capacity loss and poor electrochemical stability. Therefore, it is difficult to be effectively applied to cathode material systems with higher voltages. Improving the high-voltage stability of ether electrolytes is of great significance.

[0003] Adding electrolyte additives or using solid electrolytes can improve the oxidative stability of the electrolyte. Although the former is effective, the cost is relatively high. The latter has low ionic conductivity and poor interfacial contact with the electrolyte, which cannot meet the current needs of high-rate fast charging of sodium-ion batteries.

[0004] Based on the above reasons, this application is hereby filed. Summary of the invention

[0005] Based on the above reasons, in view of the problems or defects of ether electrolytes in the prior art, such as poor oxidation stability and easy decomposition at high voltage, the purpose of the present invention is to provide a high-voltage full-ether gel electrolyte and a preparation method thereof and application in quasi-solid-state sodium ion batteries, so as to solve or at least partially solve the above-mentioned technical defects in the prior art: the full-ether gel electrolyte prepared by the present invention is not only resistant to high voltage (>4.7V), but also has an ionic conductivity equivalent to that of a liquid electrolyte, and has the mechanical strength of a solid electrolyte, while ensuring the electrochemical performance of the battery, further improving the safety performance and cycle performance of the battery.

[0006] In order to achieve one of the above purposes of the present invention, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a high-voltage all-ether gel electrolyte, the method specifically comprising the following steps:

[0008] (1) dissolving the sodium salt in an ether organic solvent according to a preset ratio and mixing the mixture evenly to obtain an electrolyte;

[0009] (2) adding the polymerizable monomers to the electrolyte of step (1) in a preset ratio and mixing them evenly to obtain a precursor solution;

[0010] (3) adding the initiator to the precursor solution of step (2) in a preset ratio, mixing evenly and allowing the resulting mixed solution to stand to obtain the high-voltage all-ether gel electrolyte.

[0011] In some embodiments, the sodium salt in step (1) is sodium hexafluorophosphate (NaPF 6 ), sodium perchlorate (NaClO 4 ) or sodium tetrafluoroborate (NaBF 4 ) etc.

[0012] In some embodiments, the ether organic solvent in step (1) is at least one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether or tetraethylene glycol dimethyl ether.

[0013] Specifically, in the above technical solution, the amount of the ether organic solvent used in step (1) is not specifically limited, as long as the sodium salt can be completely and evenly dissolved. For example, in some embodiments of the present invention, the concentration of the sodium salt in the electrolyte is 0.1-1 mol L -1 .

[0014] In some embodiments, the uniform mixing method in step (1) is stirring, and the stirring time is 2-4 hours and the stirring speed is 500-1000 rpm.

[0015] In some embodiments, the polymerizable monomer in step (2) is at least one of trioxane, 1,3-dioxane or 1,4-dioxane.

[0016] In some embodiments, the mass ratio of the polymerizable monomer to the electrolyte in step (2) is between 0.3:2 and 1:2, and preferably 0.5:2.

[0017] In some embodiments, the uniform mixing method in step (2) is also stirring, and the stirring time is 1.5-3.5 hours and the stirring speed is 500-1000 rpm.

[0018] In some embodiments, the initiator in step (3) is any one of boron trifluoride ether solvent, tin trifluoromethanesulfonate, aluminum trifluoromethanesulfonate, lithium tetrafluoroborate or sodium hexafluorophosphate.

[0019] In some embodiments, the mass of the initiator in step (3) is between 0.5% and 2% of the mass of the precursor solution.

[0020] In some embodiments, the uniform mixing method in step (3) is also stirring, and the stirring time is 10-30 minutes and the stirring speed is 500-1000 rpm.

[0021] In some embodiments, the standing time in step (3) is 12-24 hours. The purpose of the standing time is to allow the polymerizable monomers in the precursor solution to undergo a self-polymerization reaction to generate a gel under the action of the initiator.

[0022] The second object of the present invention is to provide a high-voltage all-ether gel electrolyte prepared by the method described above.

[0023] The third object of the present invention is to provide an application of the high-voltage all-ether gel electrolyte prepared by the method described above in the field of sodium metal or sodium ion batteries, especially in quasi-solid-state sodium ion batteries.

[0024] In some embodiments, the quasi-solid-state sodium ion battery is at least one of an R2032 button battery, a single-layer soft-pack battery, or a multi-layer soft-pack battery.

[0025] The fourth object of the present invention is to provide a quasi-solid-state sodium ion battery, comprising: a gel electrolyte, a sodium metal sheet, a positive electrode sheet, a diaphragm and a battery shell, wherein: the gel electrolyte is a high-voltage all-ether gel electrolyte prepared by the method described above in the present invention.

[0026] In some embodiments, the membrane is a glass fiber membrane.

[0027] In some embodiments, the positive electrode material used in the positive electrode plate is composed of an active substance, a conductive carbon material, a binder and a dispersing solvent, wherein the mass ratio of the active substance to the positive electrode material is 70-90%.

[0028] In some preferred embodiments, the active substance is any one of sodium vanadium phosphate, sodium vanadium fluorophosphate or sodium vanadium oxyfluorophosphate. The conductive carbon material includes at least one of Ketjen black, acetylene black, superconducting carbon black, carbon fiber, carbon nanotubes, etc. The binder is at least one of polytetrafluoroethylene, polyvinylidene fluoride, sodium carboxymethyl cellulose, polyvinyl alcohol or butadiene-styrene resin. The dispersing solvent is at least one of N-methylpyrrolidone, N,N-dimethylformamide, ethanol or methanol.

[0029] A fifth object of the present invention is to provide a method for preparing the quasi-solid-state sodium ion battery described above, comprising the following steps:

[0030] A positive electrode sheet and a metal sodium sheet are placed on both sides of the fiber diaphragm carrier, respectively, and a mixed solution containing sodium salt, polymerization monomer and initiator is injected, encapsulated in a button battery, and placed in a constant temperature and humidity chamber at 25°C for 12-24 hours to obtain the quasi-solid-state sodium ion battery; wherein: the mixed solution containing sodium salt, polymerization monomer and initiator is the mixed solution prepared in step (3) of the method described above.

[0031] Compared with the prior art, the technical solution implemented by the design idea of ​​the present invention can achieve the following effects:

[0032] (1) While maintaining the advantages of existing ether electrolytes, the present invention provides a larger HOMO-LOMO energy difference after the monomer ring is opened, so as to significantly enhance its antioxidant capacity. The high-voltage all-ether gel electrolyte prepared by the present invention is applied to sodium metal or sodium ion batteries, which can greatly reduce the problem of high voltage decomposition of the battery during the charge and discharge process, and the cycle performance of the battery is greatly enhanced.

[0033] (2) The raw materials of the present invention are cheap and easily available, and the preparation method of the gel electrolyte is simple. The quasi-solid-state battery prepared by in-situ polymerization has good interface contact between the gel electrolyte and the electrode material, has a small interface resistance, and can enhance the further transmission of ions.

[0034] (3) When the present invention uses boron trifluoride ether as an initiator, a small amount of boron trifluoride can decompose and participate in the formation of the electrolyte interface, which is beneficial to the stability of the interface.

[0035] (4) The ionic conductivity of the gel electrolyte prepared by using sodium hexafluorophosphate, diethylene glycol dimethyl ether, trioxane monomer, and boron trifluoride ether initiator in the preferred embodiment of the present invention is 1.99 mS cm -1 , the voltage window can reach 5.0V.

[0036] (5) The quasi-solid-state sodium ion battery prepared by using the gel electrolyte and sodium vanadium oxyfluorophosphate as the positive electrode has a first cycle charge capacity of 117 mAh g at a rate of 5C. -1 , the discharge capacity is 107 mAh g -1 The first cycle coulombic efficiency is 91.45%. After 500 cycles, it still has 100mAh g -1 The specific capacity, capacity retention rate and average coulombic efficiency are 99.6%, showing the good high-voltage cycle performance of the gel electrolyte. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

[0038] Figure 1 This is a scanning electron microscope image obtained after the mixed solution prepared in step (3) of Example 3 is fully infiltrated into the glass fiber diaphragm and allowed to stand for 12 hours;

[0039] Figure 2 is a comparison chart of ionic conductivities of gel electrolyte-3, gel electrolyte-4, gel electrolyte-5, gel electrolyte-6, gel electrolyte-7, and gel electrolyte-9 prepared in Examples 1-6 of the present invention, respectively;

[0040] Figure 3 It is a voltage window comparison diagram of the gel electrolyte-3, gel electrolyte-4, gel electrolyte-5 prepared in Examples 1-3 of the present invention respectively and the sodium ion electrolyte prepared in Comparative Example 1;

[0041] Figure 4 The comparison chart shows the electrochemical impedance spectroscopy results obtained by dropping the mixed solutions prepared in step (3) of Examples 7-10 onto four identical glass fiber separators and leaving the assembled batteries to rest for 12 hours.

[0042] Figure 5 The figures are charge comparison diagrams of the batteries prepared by Application Example 1 and Comparative Example 1, respectively.

[0043] Figure 6 The charge and discharge curves of the battery prepared in Example 1 are shown in FIG.

[0044] Figure 7 This is a graph showing the cycle performance of the battery prepared in Application Example 1. DETAILED DESCRIPTION

[0045] The present invention provides a high-voltage all-ether gel electrolyte, a preparation method thereof, and an application thereof in a quasi-solid-state sodium ion battery. The preparation method comprises: firstly, dissolving a sodium salt in an ether organic solvent to obtain an electrolyte; secondly, adding a polymerization monomer to the electrolyte and stirring the electrolyte sufficiently to obtain a precursor solution; finally, adding an initiator to the precursor solution and stirring the precursor solution sufficiently to induce a self-polymerization reaction to obtain the high-voltage all-ether gel electrolyte.

[0046] The high-voltage all-ether gel electrolyte of the present invention is prepared by in-situ polymerization, which can form a tighter electrode / electrolyte interface, which is beneficial to the interfacial transmission of ions. In addition, the monomers used in the present invention are cyclic ethers, and this all-ether electrolyte can further demonstrate the advantages of ethers and give the battery better electrochemical performance.

[0047] The high-voltage all-ether gel electrolyte prepared by the present invention also has high ionic conductivity and high antioxidant capacity, and can be used to prepare high-voltage, high-rate quasi-solid-state sodium ion batteries. In addition, the method is low in cost, simple in process, convenient in operation, and easy to realize commercial production.

[0048] The present invention is further described in detail below through implementation cases. This implementation case is implemented based on the technology of the present invention, and a detailed implementation method and specific operation process are now given to illustrate that the present invention is creative, but the protection scope of the present invention is not limited to the following implementation cases.

[0049] According to the information contained in this application, various changes can be easily made to the precise description of the present invention for those skilled in the art.It should be understood that the scope of the present invention is not limited to defined processes, properties or components, because these embodiments and other descriptions are only for illustrating specific aspects of the present invention.

[0050] In order to better understand the present invention but not to limit the scope of the present invention, all the numbers used in this application to express the amount, percentage, and other numerical values ​​should be understood as modified by the word "about" in all cases. Therefore, unless otherwise specified, the numerical parameters listed in the specification are approximate values, which may be changed according to the different ideal properties attempted to be obtained. Each numerical parameter should at least be regarded as obtained based on the reported significant figures and by conventional rounding methods.

[0051] The equipment and raw materials used in the present invention can be purchased from the market or are commonly used in the art. The methods in the following embodiments are all conventional methods in the art unless otherwise specified.

[0052] The test methods for ionic conductivity and electrochemical performance involved in the following embodiments or application examples of the present invention are as follows:

[0053] Ionic conductivity test: Use stainless steel sheet as counter electrode and working electrode, glass fiber as diaphragm, add initiator and stir the mixture and drop it on the glass fiber, assemble the battery in the order of negative electrode shell, steel sheet, glass fiber, steel sheet, shrapnel and positive electrode shell, let it stand for 12 hours for electrochemical impedance spectroscopy test, and calculate the ionic conductivity according to the formula L / AR, where L is the thickness of the prepared gel electrolyte, in centimeters; A is the area of ​​the prepared gel electrolyte, in square centimeters; R is the impedance value obtained by the test, in ohms.

[0054] Voltage window test: Use sodium metal as the counter electrode, stainless steel sheet as the working electrode, and glass fiber as the diaphragm. Add the initiator and stir the resulting mixture and drop it on the glass fiber. Assemble the battery in the order of negative electrode shell, sodium sheet, glass fiber, steel sheet, shrapnel, and positive electrode shell. Let it stand for more than 12 hours for linear sweep voltammetry test.

[0055] Electrochemical impedance spectroscopy test: Sodium metal is used as the counter electrode and working electrode, and glass fiber is used as the diaphragm. The mixed solution obtained by adding the initiator and stirring is dropped onto the glass fiber. The battery is assembled in the order of negative electrode shell, sodium sheet, glass fiber, sodium sheet, steel sheet, shrapnel, and positive electrode shell. The battery is left to stand for more than 12 hours for electrochemical impedance spectroscopy test.

[0056] Charging comparison test: using sodium metal as the negative electrode, positive electrode, and glass fiber as the separator, the mixed solution obtained by adding the initiator and stirring is dripped on the glass fiber, and the battery is assembled in the order of negative electrode shell, negative electrode, glass fiber, positive electrode, steel sheet, shrapnel, and positive electrode shell. The battery is left to stand for more than 12 hours for a constant rate charging test. The test rate is 1C and the measurement range is 2.4-4.5V; wherein: the preparation method of the positive electrode is the same as the preparation method of the positive electrode in Application Example 1.

[0057] Charge and discharge test: using sodium metal as the negative electrode, positive electrode, and glass fiber as the separator, the solution with the initiator added and stirred was dripped onto the glass fiber, and the battery was assembled in the order of negative electrode shell, negative electrode, glass fiber, positive electrode, steel sheet, shrapnel, and positive electrode shell. The battery was left to stand for 12 hours for constant rate charge and discharge test. The test rate was 5C and the measurement range was 2.4-4.5V; wherein: the preparation method of the positive electrode was the same as the preparation method of the positive electrode in Application Example 1.

[0058] Example 1 (mass ratio of polymerized monomer to electrolyte is 0.3:2)

[0059] A method for preparing a high-voltage all-ether gel electrolyte (labeled as gel electrolyte-3) in this embodiment specifically comprises the following steps:

[0060] (1) dissolving sodium hexafluorophosphate in diethylene glycol dimethyl ether, stirring at 1000 rpm for 2 h, and preparing an electrolyte with a concentration of 1 mol / L;

[0061] (2) adding 0.3 g of the polymerized monomer trioxane to 2 g of the electrolyte described in step (1), stirring at 1000 rpm for 2 h to obtain a precursor solution;

[0062] (3) Adding the initiator boron trifluoride etherate to the precursor solution of step (2), continuing to stir at 1000 rpm for 10 min, and allowing the resulting mixed solution to stand for 12 h to obtain the high-voltage all-ether gel electrolyte; wherein the mass ratio of the boron trifluoride etherate to the precursor solution is 0.5:100.

[0063] Example 2 (mass ratio of polymerized monomer to electrolyte is 0.4:2)

[0064] The preparation method of a high-voltage all-ether gel electrolyte (labeled as gel electrolyte-4) in this embodiment is basically the same as that in Example 1, except that the amount of the polymerized monomer trioxane used in step (2) of this embodiment is 0.4 g.

[0065] Example 3 (mass ratio of polymerized monomer to electrolyte is 0.5:2)

[0066] The preparation method of a high-voltage all-ether gel electrolyte (labeled as gel electrolyte-5) in this embodiment is basically the same as that in Example 1, except that the amount of the polymerized monomer trioxane used in step (2) of this embodiment is 0.5 g.

[0067] Example 4 (mass ratio of polymerized monomer to electrolyte is 0.6:2)

[0068] The method for preparing a high-voltage all-ether gel electrolyte (labeled as gel electrolyte-6) in this embodiment is basically the same as that in Example 1, except that the amount of the polymerized monomer trioxane used in step (2) of this embodiment is 0.6 g.

[0069] Example 5 (mass ratio of polymerized monomer to electrolyte is 0.7:2)

[0070] The method for preparing a high-voltage all-ether gel electrolyte (labeled as gel electrolyte-7) in this embodiment is basically the same as that in Example 1, except that the amount of the polymerized monomer trioxane used in step (2) of this embodiment is 0.7 g.

[0071] Example 6 (mass ratio of polymerized monomer to electrolyte is 0.9:2)

[0072] The method for preparing a high-voltage all-ether gel electrolyte (labeled as gel electrolyte-9) in this embodiment is basically the same as that in Example 1, except that the amount of the polymerized monomer trioxane used in step (2) of this embodiment is 0.9 g.

[0073] Comparative Example 1

[0074] A method for preparing a sodium ion electrolyte in this comparative example, the method specifically comprises the following steps:

[0075] Sodium hexafluorophosphate was dissolved in diethylene glycol dimethyl ether, and the mixture was stirred at 1000 rpm for 2 hours to prepare a sodium ion electrolyte with a concentration of 1 mol / L.

[0076] Test result analysis:

[0077] The mixed solution prepared in step (3) of Example 3 was dripped onto the glass fiber diaphragm and allowed to stand for 12 hours after being fully soaked. Figure 1 This is a scanning electron microscope image of the glass fiber separator after standing for 12 hours. As shown in the figure, the gel electrolyte is evenly distributed on the glass fiber after curing, and there is a lot of electrolyte inside.

[0078] Figure 2 The ionic conductivity comparison diagram of gel electrolyte-3, gel electrolyte-4, gel electrolyte-5, gel electrolyte-6, gel electrolyte-7, and gel electrolyte-9 prepared in Examples 1-7, respectively. As shown in the figure, as the monomer ratio increases, the ionic conductivity of the gel electrolyte gradually decreases. The ionic conductivity of gel electrolyte-3, gel electrolyte-4, gel electrolyte-5, gel electrolyte-6, gel electrolyte-7, and gel electrolyte-9 are 2.2 mS cm -1 、2.19mS cm -1 、1.99mS cm -1 、1.31mS cm -1 、0.83mS cm -1 and 0.32 mS cm -1 .

[0079] Figure 3 The voltage window comparison diagrams of gel electrolyte-3, gel electrolyte-4, and gel electrolyte-5 prepared in Examples 1 to 3 are shown in the figure. As shown in the figure, as the monomer ratio increases, the current of the gel electrolyte increases significantly, and the corresponding potential also increases significantly, indicating that it has higher oxidation stability.

[0080] Example 7

[0081] A method for preparing a high-voltage all-ether gel electrolyte (labeled as initiator-0.5) in this embodiment specifically comprises the following steps:

[0082] (1) dissolving sodium hexafluorophosphate in diethylene glycol dimethyl ether, stirring at 1000 rpm for 2 h, and preparing an electrolyte with a concentration of 1 mol / L;

[0083] (2) adding 0.5 g of the polymerized monomer trioxane to 2 g of the electrolyte described in step (1), stirring at 1000 rpm for 2 h to obtain a precursor solution;

[0084] (3) Adding the initiator boron trifluoride etherate to the precursor solution of step (2), continuing to stir at 1000 rpm for 10 min, and allowing the resulting mixed solution to stand for 12 h to obtain the high-voltage all-ether gel electrolyte; wherein the mass ratio of the boron trifluoride etherate to the precursor solution is 0.5:100.

[0085] Example 8

[0086] The preparation method of a high-voltage all-ether gel electrolyte (labeled as initiator-1) in this embodiment is basically the same as that in Example 7, except that the mass ratio of boron trifluoride ether to the precursor solution in step (3) of this embodiment is 1:100.

[0087] Example 9

[0088] The preparation method of a high-voltage all-ether gel electrolyte (labeled as initiator-1.5) in this embodiment is basically the same as that in Example 7, except that the mass ratio of boron trifluoride ether to precursor solution in step (3) of this embodiment is 1.5:100.

[0089] Example 10

[0090] The preparation method of a high-voltage all-ether gel electrolyte (labeled as initiator-2) in this embodiment is basically the same as that in Example 7, except that the mass ratio of boron trifluoride ether to the precursor solution in step (3) of this embodiment is 2:100.

[0091] Using sodium metal as both the counter electrode and the working electrode and glass fiber as the separator, the mixed solutions prepared in step (3) of Examples 7-10 were dripped onto four identical glass fiber separators, and the assembled battery was left to stand for 12 hours before an electrochemical impedance spectroscopy test. Figure 4 The impedance test result is shown in the figure. As shown in the figure, with the increase of initiator content, the interface impedance of the symmetrical battery increases, indicating that too high initiator content will cause serious side reactions at the interface, which is not conducive to ion transmission. Figure 4 It can be seen that the optimal amount of initiator is 0.5% of the mass of the precursor solution.

[0092] Application Example 1

[0093] A quasi-solid-state sodium ion battery in this application embodiment includes a gel electrolyte, a sodium metal sheet, a positive electrode sheet, a separator and a battery shell. The preparation method of the quasi-solid-state sodium ion battery comprises the following steps:

[0094] A positive electrode sheet and a metal sodium sheet are placed on both sides of the fiber diaphragm carrier, respectively, and the mixed solution prepared in step (3) of Example 7 is injected, encapsulated in a button battery, and placed in a constant temperature and humidity chamber at 25° C. for 12 hours to obtain the quasi-solid-state sodium ion battery;

[0095] Wherein: the positive electrode material used in the positive electrode plate is composed of active material sodium vanadium fluorophosphate, conductive carbon material, binder and dispersing solvent, wherein: the mass ratio of the active material to the positive electrode material is 70-90%. The specific preparation method of the positive electrode plate is as follows: the active material sodium vanadium fluorophosphate, acetylene black and binder (PVDF) are added to the solvent (1-methyl-2-pyrrolidone) in a mass ratio of 7:2:1, zirconium balls are added, and then ball milled on a ball mill for 3 to 5 times, each time for 3 minutes. Use the scraping method to evenly coat the ball-milled paste sample on a clean aluminum foil. The coating thickness can be controlled by adjusting the scraper as needed, and then the coated aluminum foil is placed in a 120°C vacuum oven to dry for 12 hours. After taking it out, it is beaten into a 12mm diameter disc with a sheet machine for testing. In the experiment, the coating load was controlled at 0.8-1.2mg / cm 2 .

[0096] Application Comparative Example 1

[0097] The structure and preparation method of the quasi-solid-state sodium ion battery of this application comparison example are basically the same as those of application example 1, with the only difference being that the electrolyte used in this application comparison example is the sodium ion electrolyte prepared in comparison example 1.

[0098] Figure 5 The charging comparison diagram of the battery prepared by using Example 1 and Comparative Example 1 is shown in the figure. As shown in the figure, the battery electrolyte prepared by using Comparative Example 1 decomposes at about 4.4V and cannot meet the high-voltage charging test of sodium vanadium oxyfluorophosphate. However, the battery prepared by using Example 1 can pass the high-voltage charge and discharge test of ether gel electrolyte without decomposition at 4.5V.

[0099] Figure 6 The first three cycles of charge and discharge curves of the battery prepared in Example 1 are shown in the figure. As shown in the figure, the first cycle charge capacity of the battery is 117 mAh g -1 , the discharge capacity is 107 mAh g -1 The Coulomb efficiency of the first cycle was 91.45%; from the second and third cycles, the Coulomb efficiency was 98.4% and 98.7%, showing good Coulomb efficiency.

[0100] Figure 7 The cycle performance diagram of the battery prepared in Example 1 is shown in the figure. As shown in the figure, after 500 cycles at 5C high rate, it still has 100 mAh g -1 The specific capacity and capacity retention rate are 93.5%, showing the good high-voltage cycle performance of the gel electrolyte.

Claims

1. A method for preparing a high-voltage all-ether gel electrolyte, characterized in that: The method specifically comprises the following steps: (1) dissolving the sodium salt in an ether organic solvent according to a preset ratio and mixing the mixture evenly to obtain an electrolyte; (2) adding the polymerizable monomers to the electrolyte of step (1) in a preset ratio and mixing them evenly to obtain a precursor solution; (3) adding the initiator to the precursor solution of step (2) in a preset ratio, mixing evenly and allowing the resulting mixed solution to stand to obtain the high-voltage all-ether gel electrolyte.

2. The preparation method according to claim 1, characterized in that: The ether organic solvent in step (1) is at least one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether or tetraethylene glycol dimethyl ether.

3. The preparation method according to claim 1, characterized in that: The polymerization monomer in step (2) is at least one of trioxane, 1,3-dioxane or 1,4-dioxane.

4. The preparation method according to claim 1, characterized in that: The mass ratio of the polymerized monomer to the electrolyte in step (2) is between 0.3:2 and 1:

2.

5. The preparation method according to claim 1, characterized in that: The initiator in step (3) is any one of boron trifluoride ether solvent, tin trifluoromethanesulfonate, aluminum trifluoromethanesulfonate, lithium tetrafluoroborate or sodium hexafluorophosphate.

6. The preparation method according to claim 1, characterized in that: The mass of the initiator in step (3) is between 0.5% and 2% of the mass of the precursor solution.

7. The preparation method according to claim 6, characterized in that: The standing time in step (3) is 12-24 hours.

8. A high-voltage all-ether gel electrolyte prepared by the method according to any one of claims 1 to 7.

9. Application of the high-voltage all-ether gel electrolyte prepared by the method according to any one of claims 1 to 7 in the field of sodium metal or sodium ion batteries.

10. A quasi-solid-state sodium ion battery, comprising: A gel electrolyte, a sodium metal sheet, a positive electrode sheet, a separator and a battery shell, characterized in that the gel electrolyte is a high-voltage full-ether gel electrolyte prepared by the method according to any one of claims 1 to 7.

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