Preparation method of organic PSF modified NZZSP electrolyte material and application research of sodium ion battery

Abstract

The application belongs to the technical field of sodium ion battery materials, and particularly relates to a preparation method of an organic PSF modified NZZSP electrolyte material and application research of the sodium ion battery. The preparation method of the NASICON type solid-state composite electrolyte material can include the following steps: preparing a doped modified NASICON electrolyte sheet through a high-temperature solid-phase synthesis method, and then constructing an organic PSF interface coating layer on the surface of the modified NASICON electrolyte sheet through an in-situ polymerization method. The organic PSF modified NZZSP electrolyte prepared in the application effectively improves the electrochemical performance of the sodium ion battery, wherein the in-situ polymerized organic PSF modification coating layer can effectively improve the electrolyte / electrode interface contact, and can form a stable and uniform electrolyte / electrode interlayer. 2+ Partially doped and substituted Zr 4+ The Si / P ratio and Zn Benefiting from the synergistic effect of the two, the prepared organic PSF modified NZZSP electrolyte exhibits excellent capacity retention rate and cycle stability in the sodium ion battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy battery materials, and more particularly to a preparation method of an organic PSF modified NZZSP electrolyte material and application research of the material in sodium ion batteries. BACKGROUND

[0002] Na and Li belong to the same category of alkali metals and have similar electrochemical properties, but sodium resources are abundant in origin, sufficient in crust content and widely distributed, and are a very promising low-cost alternative material that can meet the huge demand for resources for future large-scale energy storage. However, similar to lithium ion batteries (LIBs), when traditional organic liquid electrolytes are used to match sodium ion batteries (SIBs), safety problems caused by the reaction between flammable organic electrolytes and active sodium metal are encountered, the most prominent of which is the growth of sodium dendrites, which can cause short circuits and even explosions in SIBs. Although the addition of flame retardants, the development of high-temperature-resistant separators, the surface modification of positive and negative electrode materials, the optimization design of battery structure and the improvement of cooling system can to some extent alleviate the safety problems during the use of liquid batteries, but they cannot ensure the safe and efficient long-term operation of large-capacity and high-power battery systems. Therefore, the use of solid-state electrolytes can effectively eliminate various problems caused by traditional liquid organic electrolytes, making the battery safer and having a longer cycle life, thereby realizing high-energy density and high-safety sodium metal batteries.

[0003] At present, the most promising types of ceramic electrolytes are Na-β-A12O3, perovskite structure, garnet structure and NASICON structure oxide electrolytes. Among them, the NASICON structure ceramic electrolyte (Li 1+x Al x Ti 2-x (PO4)3, Na 1+ x Zr2Si x P 3-x O 12 ) has stable chemical properties, a wide electrochemical window and relatively high ionic conductivity (which can reach 10 -3 S cm -1), but due to its complex interface contact state with the solid-state metal electrode, it is easy to produce interface contact resistance and metal dendrite growth, thereby causing poor cycle performance of the obtained solid-state metal battery. In order to solve the problems of poor electrochemical performance caused by large interface resistance of NASICON solid electrolyte and metal dendrite growth, researchers have developed various strategies, such as doping modification of electrolyte, surface coating of positive electrode material, optimization of synthesis method of electrolyte, etc. However, there are still problems such as low ionic conductivity, poor physical contact between electrolyte and positive and negative electrodes. Therefore, it is necessary to design and prepare NASICON composite electrolyte material with simple preparation method and excellent performance. SUMMARY

[0004] To overcome at least one problem existing in the prior art, the primary object of the present application is to provide a NZZSP electrolyte material modified by organic PSF modification.

[0005] The second object of the present application is to provide a preparation method of the above-mentioned NZZSP electrolyte material modified by organic PSF modification.

[0006] The third object of the present application is to provide the application of the above-mentioned NZZSP electrolyte material modified by organic PSF modification. The organic PSF modified NZZSP electrolyte applied in sodium ion battery shows good electrochemical performance, has the advantages of high safety, good interface compatibility, excellent cycle stability, etc.

[0007] To achieve the above-mentioned objects, the present application provides the following solutions:

[0008] The present application provides a NZZSP electrolyte material modified by organic PSF modification. The NZZSP electrolyte material modified by organic PSF modification includes a NASICON type oxide ceramic sheet, and an organic PSF polymer layer coated on both sides of the NASICON type oxide ceramic sheet. The modified NASICON type oxide ceramic electrolyte is obtained by high-temperature solid-phase synthesis method, and then the organic PSF polymer layer is introduced on both sides of the modified NASICON type oxide ceramic sheet by in-situ polymerization. The modified NZZSP electrolyte material effectively inhibits the penetration of dendrites in the electrolyte, and the modification of organic PSF can effectively improve the interface contact of the electrolyte / electrode.

[0009] The present application also provides a preparation method of the above-mentioned NZZSP electrolyte material modified by organic PSF, comprising the following steps:

[0010] S1. The Na2CO3, ZrO2, ZnO, SiO2 and NH4H2PO4 are weighed according to the stoichiometric ratio, then dispersed in anhydrous ethanol and ball milled, then pressed and sintered, and finally polished to obtain a modified NASICON type electrolyte sheet;

[0011] S2. Add SN, FEC and NaPF6 into the PEGDA solution, stir at room temperature until completely dissolved, then add AIBN as initiator, continue to stir at room temperature until completely dissolved, i.e. to obtain a PSF precursor solution;

[0012] S3. Construct the interfacial coating by in-situ polymerization method, when assembling the battery, drop the PSF precursor solution at the NZZSP electrolyte / cathode interface and NZZSP electrolyte / anode interface respectively; then place the battery in a 60 ℃ oven for 12 h, so that the PEGDA is fully polymerized at the electrolyte / electrode interface to form a PSF modified layer.

[0013] Further technical solutions of the present application: the preparation of the modified NASICON electrolyte in step S1, specifically comprising the following steps:

[0014] S11. Weigh Na2CO3, ZrO2, SiO2, NH4H2PO4 and ZnO according to the stoichiometric ratio, then disperse them in anhydrous ethanol and ball mill for 12 h.

[0015] S12. Pour the solution after ball milling into a watch glass and transfer it to an oven at 80 ℃ for drying for 12 h to remove ethanol. Then grind the dried powder, ball mill and dry it under the same conditions as above.

[0016] S13. Press the dried powder into a disc with a diameter of 15 mm and sinter it at 1200 ℃ for 10 h to obtain a modified NASICON electrolyte disc.

[0017] S14. Grind and polish the modified NASICON electrolyte disc by a grinding and polishing machine.

[0018] Further technical solutions of the present application: The Na2CO3 and NH4H2PO4 in step S11 should be appropriately excessive.

[0019] Further technical solutions of the present application: The rotation speed of the ball mill in step S11 is set to 400 rpm.

[0020] Further technical solutions of the present application: The powder after sintering in step S12 should be ground as finely as possible. The ball milling time is still 12 h, and the drying condition is still 80 ℃ for 12 h.

[0021] Further technical solutions of the present application: In step S13, the pressure needs to be increased to 15 MPa ~ 20 MPa.

[0022] The further technical solution of the application: the grits of the sandpaper for polishing in step S14 are 240, 400, 2000, 4000 and 5000 in turn.

[0023] The further technical solution of the application: the preparation of the PEGDA-SN-FEC precursor solution (PSF-pre) in step S2 specifically comprises the following steps:

[0024] S21. Add SN, FEC and NaPF6 to the PEGDA solution, and stir at room temperature for 3 h to make them completely dissolved.

[0025] S22. Then add AIBN as an initiator, and continue to stir at room temperature until completely dissolved, thereby obtaining the PSF precursor solution.

[0026] The further technical solution of the application: the mass of the PEGDA, SN, FEC and NaPF6 in step S21 is 1 g, 1.2 g, 0.13 g and 0.4 g respectively.

[0027] The further technical solution of the application: the mass of the initiator AIBN in step S22 is 0.005 g.

[0028] The further technical solution of the application: the experimental operation in steps S21 and S22 is performed in a glove box under an Ar gas atmosphere with H2O < 0.1 and O2 < 0.1.

[0029] The further technical solution of the application: the preparation of the PEGDA-SN-FEC polymer (PSF) coating in step S3 specifically comprises the following steps:

[0030] S31. The interface coating is constructed by using an in-situ polymerization method. When assembling the battery, the PSF precursor solution is added dropwise at the NZZSP electrolyte / positive electrode interface and the NZZSP electrolyte / negative electrode interface.

[0031] S32. Then the battery is placed in a 60 ℃ oven for 12 h, so that the PEGDA is fully polymerized at the electrolyte / electrode interface to form a PSF modification layer.

[0032] The further technical solution of the application: the amount of the PSF precursor solution added dropwise in step S31 is 20 μL, and the coating is uniform.

[0033] The further technical solution of the application: the coating treatment in step S3 is performed under an Ar gas atmosphere.

[0034] The application skillfully uses NASICON electrolyte as a matrix, and a modified NZZSP electrolyte is prepared by a high-temperature solid-phase synthesis method, then a PSF precursor solution is added dropwise at the NZZSP electrolyte / cathode interface and the NZZSP electrolyte / anode interface when assembling the battery, and an organic PSF modification layer is polymerized in situ at 60 DEG C. Meanwhile, the PSF-NZZSP-PSF material is used as the electrolyte of the sodium ion battery, and excellent electrochemical performance (excellent cycle performance and rate performance) is obtained.

[0035] The application also provides a sodium ion battery comprising the organic PSF modified NZZSP electrolyte material of claim 1.

[0036] The application also provides a preparation method of the sodium ion battery, comprising the following steps:

[0037] S1'. The organic PSF modified NZZSP electrolyte material of claim 1 is polished with sandpaper and sealed well;

[0038] S2'. In an anhydrous and anaerobic glove box, the positive electrode shell of the sodium ion battery is placed on a cushion plate with the opening upward, the positive electrode sheet is placed in the positive electrode shell, then 20 μL of the PSF precursor solution is added dropwise, and the electrolyte material of step S1' is placed in the positive electrode sheet; 20 μL of the PSF precursor solution is added dropwise again, the sodium metal sheet is clamped and placed in the electrolyte sheet, and finally the gasket and spring are placed in the sodium metal sheet, and the negative electrode shell is sealed, then the battery is placed in a 60 DEG C oven for 12 h, and the sodium ion battery is obtained.

[0039] Further, the assembled battery is placed in a 60 DEG C oven for 12 h, so that the PSF precursor solution is fully polymerized at the electrolyte / electrode interface to form a PSF modification layer; the positive electrode sheet used is Na3V2(PO4)3.

[0040] Compared with the prior art, the application has the following beneficial effects:

[0041] The application discloses a preparation method of an organic PSF modified NZZSP electrolyte material, a modified NASICON electrolyte is obtained by a high-temperature solid-phase synthesis method, then an organic PSF modification layer is formed at the electrolyte / electrode interface by in-situ polymerization, and a PSF-NZZSP-PSF composite electrolyte is obtained.

[0042] In the first aspect, Si 4+ Instead of P 5+And the low-valence cation doped Zr site can change the bottleneck size of the sodium ion transport channel and produce a higher sodium ion concentration to maintain charge balance, thereby improving the ionic conductivity. In addition, the doping of low-valence cations can promote sintering densification and grain growth, which can effectively inhibit the penetration of dendrites inside the electrolyte.

[0043] In the second aspect, the in-situ polymerized polymer electrolyte can effectively improve the electrolyte / electrode interface contact, and form a stable and uniform electrolyte / electrode interlayer. This not only improves the poor contact problem of the positive electrode side caused by the rigid interface, but also forms a stable SEI layer on the sodium metal negative electrode side to form an interface modification layer to inhibit the growth of sodium dendrites.

[0044] In the third aspect, the PSF-NZZSP-PSF composite electrolyte material described above is applied to the preparation of a sodium ion battery, which is made of an electrode sheet, a sodium metal sheet, an electrolyte sheet, a spring sheet, a gasket, and a positive and negative electrode shell. The sodium ion battery prepared by using the PSF-NZZSP-PSF composite electrolyte material has excellent electrochemical performance. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 The preparation method flow chart of the organic PSF modified NZZSP electrolyte of the present application.

[0046] Figure 2 The XRD graph of the modified NASICON electrolyte prepared in the present application.

[0047] Figure 3 The SEM and TEM graphs of the modified NASICON electrolyte powder prepared in the present application.

[0048] Figure 4 The SEM and TEM graphs of the surface of the PSF-NZZSP electrolyte prepared in the present application.

[0049] Figure 5 The impedance spectrum graph of the modified NZZSP and NZSP electrolyte prepared in the present application at room temperature.

[0050] Figure 6 The room temperature alternating current impedance spectrum of the PSF-NZZSP-PSF electrolyte material and the pure NASICON electrolyte material prepared in the present application.

[0051] Figure 7 The critical current density test graph of the Na symmetric battery of the organic PSF modified NZZSP electrolyte material prepared in the present application at room temperature.

[0052] Figure 8The PSF-NZZSP-PSF electrolyte material prepared in the present application and the pure NASICON electrolyte material as sodium symmetrical battery, the constant current cycle performance comparison chart at 0.1 mA cm -2

[0053] Figure 9 The cycle performance chart of the PSF-NZZSP-PSF electrolyte material prepared in the present application at a current density of 0.5 C.

[0054] Figure 10 The rate performance chart of the PSF-NZZSP-PSF electrolyte material prepared in the present application as sodium ion battery electrolyte. DETAILED DESCRIPTION

[0055] The embodiments of the present application will be described in detail below with examples, but those skilled in the art will understand that the following examples are only for illustration of the present application, and should not be regarded as limiting the scope of the present application. The specific conditions are not specified in the examples, and the conventional conditions or the conditions recommended by the manufacturer are used. The reagents or instruments used are not specified by the manufacturer, and are conventional products that can be obtained by commercial purchase.

[0056] It should be noted that:

[0057] In the present application, all the embodiments and preferred implementation methods mentioned in the present text can be combined to form new technical solutions, if not specifically stated.

[0058] In the present application, unless otherwise specified, each reaction or operation step can be carried out sequentially or according to the sequence. Preferably, the reaction method in the present text is carried out sequentially.

[0059] Unless otherwise specified, the professional and scientific terms used in the present text have the same meaning as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content can also be applied in the present application.

[0060] Term explanation

[0061] NZSP: Na3Zr2Si2PO 12 Abbreviation of electrolyte material;

[0062] NZZSP: Na 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 Abbreviation of electrolyte material;

[0063] PSF: abbreviation of PEGDA-SN-FEC material; ​

[0064] SEM: scanning electron microscope;

[0065] TEM: transmission electron microscope;

[0066] The application provides an organic PSF modified NZZSP electrolyte material, which comprises a NASICON type oxide ceramic material sheet and organic PSF polymer layers arranged on both sides of the NASICON type oxide ceramic sheet. The organic PSF modified NZZSP electrolyte material has good interface compatibility with the positive and negative electrodes, and improves the ionic conductivity. The modified NASICON type oxide ceramic material is obtained by a high-temperature solid-phase synthesis method, and is modified by introducing the organic PSF polymer layers on both sides of the modified NASICON type oxide ceramic sheet.

[0067] The organic PSF modified NZZSP electrolyte material in the application can improve the ionic conductivity of the electrolyte by using Si 4+ substituting P 5+ and doping Zr sites with low-valence cations; and the organic PSF polymer coating formed in situ can effectively improve the electrolyte / electrode interface contact and form a stable electrolyte / electrode interlayer.

[0068] The application ingeniously uses a NASICON electrolyte as a substrate, prepares a modified NZZSP electrolyte by a high-temperature solid-phase synthesis method, then drops PSF precursor solutions at the NZZSP electrolyte / positive electrode interface and the NZZSP electrolyte / negative electrode interface when assembling a battery, and polymerizes the organic PSF modification layer in situ at 60°C. Meanwhile, the PSF-NZZSP-PSF material is used as an electrolyte of a sodium ion battery, and excellent electrochemical performance (excellent cycle performance and rate performance) is obtained.

[0069] In terms of cycle performance, the capacity retention rate can still be as high as 94.41% after 200 cycles at a current density of 0.5 C. In terms of rate performance, the battery can normally work even at a current density of 2 C, and a reversible specific capacity of 75.2 mAhg -1 is obtained. It can be seen that the performance of the prepared PSF-NZZSP-PSF electrolyte is far superior to that of the NASICON substrate electrolyte, and has important uses in sodium ion batteries.

[0070] In another aspect, the application provides a preparation method of the above-mentioned organic PSF modified NZZSP electrolyte material, which comprises the following steps:

[0071] S1. Measuring Na2CO3, ZrO2, ZnO, SiO2 and NH4H2PO4 in stoichiometric ratio, then dispersing in anhydrous ethanol, ball milling, pressing, sintering, polishing and finally obtaining modified NASICON type electrolyte sheet;

[0072] S2. Adding SN, FEC and NaPF6 to PEGDA solution, stirring at room temperature until completely dissolved, then adding AIBN as initiator, continuing to stir at room temperature until completely dissolved, i.e. obtaining PSF precursor solution;

[0073] S3. Using in-situ polymerization method to construct interface coating, when assembling the battery, adding PSF precursor solution at NZZSP electrolyte / cathode interface and NZZSP electrolyte / anode interface respectively; then placing the battery in a 60℃ oven for 12h, so that PEGDA is fully polymerized at the electrolyte / electrode interface to form PSF modified layer.

[0074] In some preferred embodiments, the Na2CO3 and NH4H2PO4 are appropriately excessive, and the excess of Na2CO3 and NH4H2PO4 is about 10-15%.

[0075] In some preferred embodiments, the step S2 experiment is carried out in a glove box under Ar gas atmosphere with H2O <0.1 and O2 <0.1.

[0076] In some preferred embodiments, in step S1, the ball milling time is 12 hours, and the sintering temperature is 1200℃ for 10 hours.

[0077] In some preferred embodiments, in step S2, the stirring time is 3h.

[0078] In some preferred embodiments, in step S3, the amount of organic PSF precursor solution added is 20 μL.

[0079] In some preferred embodiments, in step S3, the inert gas is argon atmosphere.

[0080] The application also provides a sodium ion battery, wherein the electrolyte is the above-mentioned organic PSF modified NZZSP electrolyte material.

[0081] In another aspect, the application provides a preparation method of the above-mentioned sodium ion battery, comprising the following steps:

[0082] S1’. Polishing and sealing the doped modified NZZSP electrolyte material of claim 1 with sandpaper;

[0083] S2’. In an anhydrous and anaerobic glove box, place the positive shell of the sodium-ion battery upside down on a cushion plate, place the positive electrode sheet in the center of the positive shell, then drop 20 μL of the PSF precursor solution, and place the electrolyte material of step S1’ in the center of the electrode sheet; again drop 20 μL of the PSF precursor solution, clamp the sodium metal sheet and place it in the center of the electrolyte sheet; finally, place the gasket and spring in the center of the sodium metal sheet, cover the negative shell and seal it, then place the battery in a 60 ℃ oven for 12 h to obtain the sodium-ion battery.

[0084] Next, the preparation method of the organic PSF modified NZZSP electrolyte material and the preparation method of the sodium-ion battery are described in detail with specific examples.

[0085] Preparation of the organic PSF modified NZZSP electrolyte material

[0086] The organic PSF modified NZZSP electrolyte material is prepared by coating PSF precursor solution on both sides of the modified NASICON electrolyte sheet, and then forming PSF-NZZSP-PSF composite electrolyte through in-situ polymerization. The organic PSF modified NZZSP electrolyte has good interfacial compatibility with the positive and negative electrodes, and the preparation method is as follows:

[0087] S1. Preparation of modified NASICON electrolyte.

[0088] S11. Weigh Na2CO3, ZrO2, SiO2 and NH4H2PO4 according to the stoichiometric ratio, then disperse them in anhydrous ethanol and ball mill for 12 h at a speed of 400 rpm. After ball milling, pour the solution into a watch glass and transfer it to an oven at 80 ℃ for 12 h to remove ethanol. Then, the dried powder is sintered at 950 ℃ for 12 h.

[0089] S12. The sintered powder is ground, ball milled and dried in sequence, and the ball milling and drying conditions are the same as above.

[0090] S13. The dried powder is pressed into a circular sheet with a diameter of 15 mm and placed in a crucible. The circular sheet is sintered at 1200 ℃ for 10 h to obtain the NZZSP electrolyte sheet.

[0091] S14. Finally, the NZZSP electrolyte sheet is polished by a grinding and polishing machine (sandpaper grit: 240, 400, 2000, 4000, 5000 grit).

[0092] S2. Preparation of PEGDA-SN-FEC precursor solution.

[0093] S21. Add 1.2 g SN, 0.13 g FEC and 0.4 g NaPF6 into 1 g PEGDA solution, and stir at room temperature for 3 h to make it completely dissolved.

[0094] S22. Add 0.005 g AIBN as initiator, and continue to stir at room temperature until completely dissolved, to obtain a PSF precursor solution.

[0095] S3. Preparation of PEGDA-SN-FEC polymer (PSF) coating.

[0096] S31. Construct the interface coating by in-situ polymerization. When assembling the battery, 20 μL of PSF precursor solution is added dropwise at the NZZSP electrolyte / cathode interface and the NZZSP electrolyte / anode interface, respectively.

[0097] S32. Place the battery in a 60 °C oven for 12 h, so that PEGDA is fully polymerized at the electrolyte / electrode interface to form a PSF modification layer, to obtain a PSF-NZZSP-PSF electrolyte.

[0098] Performance characterization

[0099] The modified NASICON electrolyte powder obtained in the preparation example was observed by X-ray diffraction (XRD), and the results are shown in Figure 2 .

[0100] Among them, Figure 2 it is shown that the main diffraction peak matches well with the standard card PDF #84-1200 of monoclinic Na3Zr2Si2PO 12 , indicating that Zn 2+ is successfully doped into the NASICON lattice. The doping of low-valence Zn 2+ can promote sintering densification and grain growth, and can effectively inhibit the penetration of dendrites in the electrolyte, and also change the bottleneck size of the sodium ion transport channel, thereby improving the ionic conductivity.

[0101] The applicant also observed the modified NASICON electrolyte powder obtained in the preparation example by scanning electron microscope (SEM) and transmission electron microscope (TEM), and the results are shown in Figure 3 . Figure 3 It is shown that the NZZSP has a block structure and uniform size, and the powder particle size is about 1 μm. At the same time, the elements in the NZZSP powder are uniformly distributed, further indicating that the Zn element is successfully doped into the electrolyte, which can effectively inhibit the penetration of dendrites in the electrolyte and improve the ionic conductivity.

[0102] The prepared PSF-NZZSP electrolyte was observed by scanning electron microscope (SEM) and transmission electron microscope (TEM), and it can be seen from Figure 4 the drawings that the PSF coating has a smooth surface and can perfectly fill the scratches and gaps on the surface of the NZZSP electrolyte, thereby greatly reducing the cross-sectional impedance. At the same time, the uniform distribution of C and F elements can also be observed, indicating that the organic PSF does not aggregate on the surface of the NZZSP electrolyte sheet. The introduction of the PSF coating can make the sodium deposition uniform, thereby inhibiting the growth of sodium dendrites and reducing the possibility of short circuit of the battery; in addition, a stable SEI layer can also be formed on the sodium metal negative electrode side, thereby reducing the interface resistance.

[0103] Application Example 1 Preparation of a sodium ion battery

[0104] Preparation of a sodium symmetric battery: a CR 2032 button cell with sodium metal as the counter / reference electrode was used to construct the test battery, and the operation was carried out in an argon-filled glove box. The positive shell of the sodium ion battery was placed on the pad with the opening facing up, and the sodium metal sheet was placed in the center of the positive shell. Then the PSF-NZZSP-PSF electrolyte was placed in the center of the sodium metal sheet, and the sodium metal sheet was clamped in the center of the electrolyte sheet. Finally, the gasket and spring were placed in the center of the sodium metal sheet, and the negative shell was sealed after being covered, thereby obtaining a sodium symmetric sodium ion battery.

[0105] Preparation of a full battery: a CR 2032 button cell with sodium metal as the counter / reference electrode was used to construct the test battery, and the operation was carried out in an argon-filled glove box. The positive shell of the sodium ion battery was placed on the pad with the opening facing up, and the Na3V2(PO4)3 positive sheet was placed in the center of the positive shell. Then 20 μL of PSF precursor solution was added using a rubber head dropper, and the modified NZZSP electrolyte sheet was clamped in the center of the sheet. Then the sodium metal sheet was clamped in the center of the electrolyte sheet. Finally, the gasket and spring were placed in the center of the sodium metal sheet, and the negative shell was sealed after being covered, thereby obtaining a full battery sodium ion battery.

[0106] Test Example 1 Electrochemical performance test of a sodium symmetric battery

[0107] The sodium symmetric sodium ion battery prepared in Example 3 was tested for electrochemical performance (AC impedance spectrum and critical current density) using an electrochemical workstation. In the AC impedance spectrum test, the frequency test interval was 1M~0.1Hz;

[0108] As shown in Figure 5 , the room temperature ionic conductivity (1.37 × 10 -3 S cm -1 ) of the NZZSP electrolyte is significantly higher than that of the NZSP (6.63 × 10 -4 S cm -1). This indicates that increasing the Si / P atomic ratio and using Zn 2+ substituting Zr 4+ , the bottleneck size of sodium ion channel increases, which is more conducive to the transmission of sodium ions, and the use of low-valence cation doping will produce more sodium ion vacancies to maintain charge balance, thereby improving the ionic conductivity of the electrolyte.

[0109] As shown in Figure 6 , due to the poor interface contact between metallic sodium and rigid NZZSP electrolyte sheets, the interface impedance of the Na / NZZSP / Na battery is as high as 302 Ω cm 2 . In contrast, the interface impedance of the Na / PSF-NZZSP-PSF / Na battery is reduced to 50 Ω cm 2 , which is mainly due to the uniform and dense layer of PSF polymer on the surface of NZZSP electrolyte, effectively filling the micro defects and recesses on the surface of the electrolyte, thereby having excellent interface contact.

[0110] As shown in Figure 7 and 8 , for the critical current density test, the Na / PSF-NZSP-PSF / Na battery can be stably cycled at a current density of 0.55 mA cm -2 . This further indicates that the introduction of the PSF polymer coating can effectively improve the compatibility of the NZZSP electrolyte / sodium metal interface, reduce the interface impedance, and promote the sodium ion transmission kinetics at the interface. For the constant current cycling performance test, the overpotential of the unmodified Na / NZZSP / Na battery rapidly increases after cycling at 0.1 mA cm -2 . In contrast, the Na / PSF-NZSP-PSF / Na battery can still maintain a stable overpotential after 600 h of cycling. It can be seen that the performance of the prepared organic PSF modified NZZSP electrolyte material is far superior to that of pure NASICON electrolyte material, and has important use in sodium ion batteries.

[0111] Test Example 2: Electrochemical performance test of full battery

[0112] The full battery prepared in Experimental Example 2 was subjected to electrochemical performance (cycle performance and rate performance) tests using a multi-channel battery tester (Wuhan LanDian). In the cycle performance test, the current density was 0.5 C; in the rate performance test, the current density was 0.1 C, which was increased to 0.2 C, 0.5 C, 1 C, and 2 C in turn, and then returned to 0.1 C;

[0113] As shown in Figure 9It can be seen that, in terms of cycle performance, at a current density of 0.5 C, the battery maintains a stable discharge specific capacity and coulombic efficiency, and still retains 98.0 mAh g⁻¹ after 200 cycles. -1 The discharge specific capacity has a capacity retention rate as high as 94.41%. In the initial few cycles, the capacity shows a climbing trend, which is mainly attributed to the battery activation process during the formation of a stable SEI layer.

[0114] Depend on Figure 10 It can be seen that, in terms of rate performance, the battery can operate normally even at a current density of 2 C, and achieves 75.2 mAh g⁻¹. -1 Specific capacity. It is evident that the performance of the prepared organic PSF-modified NZZSP electrolyte material is far superior to that of pure NASICON electrolyte material, and it has important applications in sodium-ion batteries.

[0115] This application ingeniously utilizes NASICON electrolyte as a matrix and prepares a modified NZZSP electrolyte via a high-temperature solid-state synthesis method. Then, during battery assembly, PSF precursor solutions are added dropwise to the NZZSP electrolyte / positive electrode interface and the NZZSP electrolyte / negative electrode interface, respectively, and an organic PSF modification layer is polymerized in situ at 60°C. Simultaneously, this PSF-NZZSP-PSF material is used as an electrolyte in sodium-ion batteries, achieving excellent electrochemical performance (excellent cycle performance and rate performance).

[0116] In terms of cycle performance, the capacity retention rate remains as high as 94.41% after 200 cycles at a current density of 0.5 C. Regarding rate performance, the battery operates normally even at a current density of 2 C, achieving a capacity of 75.2 mAh g⁻¹. -1 The reversible specific capacity and sodium storage capacity are shown. It is evident that the performance of the prepared PSF-NZZSP-PSF electrolyte is far superior to that of the NASICON-based electrolyte, and it has important applications in sodium-ion batteries.

[0117] Compared with the prior art, the beneficial effects of this application are:

[0118] This application discloses an organic PSF-modified NZZSP electrolyte material and its preparation method. A modified NASICON electrolyte was obtained by high-temperature solid-state synthesis, and then an organic PSF modification layer was formed at the electrolyte / electrode interface by in-situ polymerization to obtain a PSF-NZZSP-PSF composite electrolyte.

[0119] Firstly, by increasing the Si / P ratio and Zn 2+ Partial doping of Zr 4+The bottleneck size of the sodium ion transmission channel can be changed and a higher sodium ion concentration can be generated to maintain charge balance, thereby improving ion conductivity. In addition, the doping of low-valence cations can promote sintering densification and grain growth, and can effectively inhibit dendrite penetration in the electrolyte.

[0120] In a second aspect, the in-situ polymerized polymer electrolyte can effectively improve the electrolyte / electrode interface contact, forming a stable and uniform electrolyte / electrode interlayer. This not only improves the poor contact problem on the positive electrode side due to the rigid interface, but also forms a stable SEI layer on the sodium metal negative electrode side to form an interface modification layer to inhibit sodium dendrite growth.

[0121] In a third aspect, the PSF-NZZSP-PSF composite electrolyte material described above is applied in the preparation of a sodium ion battery, which is made of an electrode sheet, a sodium metal sheet, an electrolyte sheet, a spring sheet, a gasket, and a positive and negative electrode shell. The sodium ion battery prepared by the PSF-NZZSP-PSF composite electrolyte material has excellent electrochemical performance.

[0122] In the description of the present specification, the description referring to the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0123] Although several embodiments of the present application have been shown and described, it will be understood by those having ordinary skill in the art that various changes, modifications, substitutions and alterations can be made thereto without departing from the principles and the spirit of the present application, the scope of which is defined by the following claims and their equivalents.

Claims

1. A Na 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 Electrolyte material characterized in that: The organic PEGDA-SN-FEC material modified Na 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 The electrolyte material includes a doped modified NASICON type oxide ceramic material sheet, and an organic PEGDA-SN-FEC polymer layer coated on both sides of the NASICON type oxide ceramic sheet, the construction of the organic PEGDA-SN-FEC polymer layer includes adding SN, FEC and NaPF6 into a PEGDA solution, stirring at room temperature until completely dissolved, then adding AIBN as an initiator, continuing to stir at room temperature until completely dissolved, that is, obtaining a PEGDA-SN-FEC precursor solution; using an in-situ polymerization method to construct the interface coating, when assembling the battery, adding the PEGDA-SN-FEC precursor solution at the electrolyte / cathode interface and the electrolyte / anode interface respectively; then placing the battery in an oven at 60 ℃ for 12 h, so that the PEGDA is fully polymerized at the electrolyte / electrode interface to form a PEGDA-SN-FEC modified layer. 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 The electrolyte / cathode interface and the Na 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 The electrolyte / anode interface is respectively added with the PEGDA-SN-FEC precursor solution; then the battery is placed in an oven at 60 ℃ for 12 h, so that the PEGDA is fully polymerized at the electrolyte / electrode interface to form a PEGDA-SN-FEC modified layer.

2. The organic PEGDA-SN-FEC material modified Na 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 A method of preparing an electrolyte material, comprising the steps of: S1. Na2CO3, ZrO2, ZnO, SiO2 and NH4H2PO4 were weighed in stoichiometric ratio, then dispersed in anhydrous ethanol and ball-milled, followed by tabletting and sintering, and finally polishing to obtain modified NASICON-type electrolyte tablets; S2. SN, FEC and NaPF6 were added to a PEGDA solution, which was stirred at room temperature until completely dissolved, then AIBN was added as an initiator, and the stirring was continued at room temperature until complete dissolution, thereby obtaining a PEGDA-SN-FEC precursor solution; S3. Constructing the interfacial coating by in-situ polymerization, when assembling the battery, drop the PEGDA-SN-FEC precursor solution on the electrolyte / positive electrode interface and the electrolyte / negative electrode interface, respectively; then, place the battery in an oven at 60 °C for 12 h, so that the PEGDA is fully polymerized at the electrolyte / electrode interface to form the PEGDA-SN-FEC modified layer. 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 electrolyte / positive electrode interface and the electrolyte / negative electrode interface, respectively; then, place the battery in an oven at 60 °C for 12 h, so that the PEGDA is fully polymerized at the electrolyte / electrode interface to form the PEGDA-SN-FEC modified layer. 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 electrolyte / positive electrode interface and the electrolyte / negative electrode interface, respectively; then, place the battery in an oven at 60 °C for 12 h, so that the PEGDA is fully polymerized at the electrolyte / electrode interface to form the PEGDA-SN-FEC modified layer.

3. Na modified with the organic PEGDA-SN-FEC material of claim 2 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 Process for the preparation of an electrolyte material, characterized in that: In step S1, the Na2CO3 and NH4H2PO4 were appropriately excessive, and the excess of Na2CO3 and NH4H2PO4 was 10-15%.

4. The organic PEGDA-SN-FEC material modified Na of claim 2 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 Process for the preparation of an electrolyte material, characterized in that: The whole operation of step S2 was carried out in a glove box under an Ar gas atmosphere with H2O < 0.1 and O2 < 0.

1.

5. The organic PEGDA-SN-FEC material modified Na of claim 3 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 Process for the preparation of an electrolyte material, characterized in that: In step S1, the ball-milling time was 12 hours, and the sintering temperature was 1200°C for 10 hours.

6. The organic PEGDA-SN-FEC material modified Na of claim 4 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 Process for the preparation of an electrolyte material, characterized in that: In step S2, the stirring time was 3 hours.

7. The organic PEGDA-SN-FEC material modified Na of claim 2 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 Process for the preparation of an electrolyte material, characterized in that: In step S3, the amount of the PEGDA-SN-FEC precursor solution added dropwise was 20 μL.

8. A sodium-ion battery, characterized in that: The electrolyte in the sodium-ion battery is a Na 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 electrolyte material.

9. A method of producing a sodium-ion battery as claimed in claim 8, characterized in that: The following steps are included: S1'. The organic PEGDA-SN-FEC material modified Na 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 Electrolyte material, sanded and sealed. S2’. In an anhydrous and oxygen-free glove box, the positive electrode shell of the sodium-ion battery was placed flat on a pad with the opening facing upwards, the positive electrode sheet was placed in the center of the positive electrode shell, then 20 μL of the PEGDA-SN-FEC precursor solution was added dropwise, and the electrolyte material of step S1’ was placed in the center of the electrode sheet; 20 μL of the PEGDA-SN-FEC precursor solution was added dropwise again, and the sodium metal sheet was clamped and placed in the center of the electrolyte sheet; finally, the gasket and spring were placed in the center of the sodium metal sheet, and the negative electrode shell was covered and sealed, then the battery was placed in a 60°C oven for 12 hours, thereby obtaining a sodium-ion battery.

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