Organic-inorganic composite solid electrolyte and preparation method and application thereof

Abstract

The invention discloses an organic-inorganic composite solid electrolyte and a preparation method and application thereof, the organic-inorganic composite solid electrolyte comprises an inorganic ceramic filler, a polymer substrate and a sodium salt; the inorganic ceramic filler is a filler formed by grafting a diamino polyethylene glycol short chain after coating sodium zirconium silicon phosphorus oxide with polydopamine; the polymer substrate is a mixture of polyethylene glycol and polyvinylidene fluoride. The preparation method comprises the following steps: dissolving the polyethylene glycol, the polyvinylidene fluoride, the inorganic ceramic filler and the sodium salt in a solvent to obtain a mixed solution, coating a base material with the mixed solution, and then performing vacuum drying to obtain the organic-inorganic composite solid electrolyte. The organic-inorganic composite solid electrolyte disclosed by the invention has relatively high ionic conductivity, good mechanical property and relatively good interface stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid electrolytes, and in particular relates to an organic-inorganic composite solid electrolyte and a preparation method and application thereof. Background Art

[0002] Due to the abundance of sodium resources and its similar properties to lithium, sodium-ion batteries have become a promising candidate for lithium-ion batteries. -1 ) and low electrochemical potential (-2.7V relative to the standard hydrogen electrode) have attracted widespread attention. However, traditional sodium metal batteries have problems with interfacial instability and sodium dendrites, which reduce the cycle life of the battery. At the same time, traditional liquid organic electrolytes also have flammable and explosive safety risks. Therefore, the development of all-solid-state batteries has become a trend in today's era (Adv.Funct.Mater.2024,34,2213584).

[0003] At present, solid electrolytes are mainly divided into inorganic solid electrolytes and polymer solid electrolytes. Inorganic solid electrolytes have a special three-dimensional framework structure, the gaps of which constitute specific sodium ion diffusion channels, so they have the characteristics of high ionic conductivity, sodium ion migration number and mechanical strength. However, their intrinsic brittleness and high hardness lead to large electrode / electrolyte interface impedance. Polymer electrolytes have the advantages of good film forming, light weight, and good compatibility with the interface between electrodes. However, in polymer electrolytes, Na + The migration of ions mainly depends on the segmental movement of the polymer in the non-crystalline region. The segmental movement of the polymer is slow at room temperature, so the room temperature ionic conductivity of the polymer electrolyte is low and the thermodynamic stability is poor.

[0004] Compared to single solid-state electrolyte systems, organic-inorganic composite electrolytes offer advantages such as flexibility, flexible processing, and excellent overall electrochemical performance, making them a promising class of solid-state electrolyte systems. In composite electrolyte systems, inorganic fillers can disrupt the crystalline regions of the polymer and form Lewis acid-base interactions with sodium salts, thereby promoting sodium ion dissociation. Furthermore, inorganic fillers can enhance the mechanical properties of the electrolyte, dissipate stress, and thereby inhibit dendrite growth. In recent years, inorganic solid electrolytes such as sodium superionic conductors (NASICONs) have been widely used as active fillers to provide additional ion diffusion pathways in composite electrolytes and stabilize the electrode / electrolyte interface. However, fillers in existing organic-inorganic composite electrolytes exhibit poor dispersion within the polymer matrix, leading to aggregation and phase separation, which can hinder ion transport pathways and reduce the electrolyte's ionic conductivity. Therefore, it is necessary to develop new organic-inorganic composite solid electrolytes to address these issues. Summary of the Invention

[0005] In order to solve the problems raised in the above background technology, the purpose of the present invention is to provide an organic-inorganic composite solid electrolyte and its preparation method and application.

[0006] In order to achieve the above-mentioned object, the technical solution adopted by the present invention is as follows: On the one hand, the present invention provides an organic-inorganic composite solid electrolyte, comprising an inorganic ceramic filler, a polymer substrate and a sodium salt;

[0007] The inorganic ceramic filler is a filler in which an active filler sodium zirconium silicon phosphorus oxide (NZSP) is coated with polydopamine (PDA) and then grafted with a short chain of bisamino polyethylene glycol (NH2-PEG-NH2), which is recorded as PDA@NZSP-g-NH2-PEG-NH2;

[0008] The polymer substrate is a mixture of polyethylene glycol (PEO) and polyvinylidene fluoride (PVDF).

[0009] Furthermore, the mass ratio of the polyethylene glycol, polyvinylidene fluoride, inorganic ceramic filler and sodium salt is 3: (0.5-1): (0.6-4): (1-1.5).

[0010] Furthermore, the sodium salt is at least one of sodium bis(trifluoromethanesulfonyl)imide, sodium trifluoromethanesulfonate, sodium hexafluorophosphate, and sodium perchlorate.

[0011] Furthermore, the preparation method of the inorganic ceramic filler is:

[0012] (1) ball milling sodium carbonate, zirconium dioxide, silicon dioxide and ammonium dihydrogen phosphate for the first time; then calcining the ball milled product for the first time in an oxygen atmosphere; after the calcination, ball milling the calcined product for the second time; then calcining the ball milled product for the second time in an oxygen atmosphere to prepare sodium zirconium silicon phosphorus oxide; after the calcination, wet ball milling the calcined product sodium zirconium silicon phosphorus oxide and sieving it; drying the sieved sodium zirconium silicon phosphorus oxide, and then adding methanol and glacial acetic acid and stirring for 12 hours to 16 hours;

[0013] (2) The acid-treated sodium zirconium silicon phosphide is centrifuged and dried, and then methanol, trishydroxymethylaminomethane and sodium hydroxide are added to obtain a sodium zirconium silicon phosphide solution, and then dopamine hydrochloride (DA) is added and stirred for 12h-16h to obtain polydopamine-coated sodium zirconium silicon phosphide; methanol and sodium hydroxide are added to the polydopamine-coated sodium zirconium silicon phosphide to obtain a polydopamine-coated sodium zirconium silicon phosphide solution, and then bisamino polyethylene glycol is added and stirred for 12h-16h for grafting to prepare an inorganic ceramic filler.

[0014] Furthermore, the mass ratio of sodium carbonate, zirconium dioxide, silicon dioxide and ammonium dihydrogen phosphate in step (1) is 2.6235:3.69:1.8:1.8975;

[0015] Preferably, the ball milling medium used in the first ball milling in step (1) is zirconia ball milling beads, the speed of the first ball milling is 500 rpm-800 rpm, the time of the first ball milling is 5 h-8 h, and the ball-to-material ratio of the first ball milling is (30-60):1;

[0016] Preferably, the temperature of the first calcination in step (1) is 800° C.-1100° C., and the time of the first calcination is 10 h-30 h;

[0017] Preferably, the ball milling medium for the second ball milling in step (1) is zirconia ball milling beads, the speed of the second ball milling is 500 rpm-800 rpm, the time of the second ball milling is 5 h-8 h, and the ball-to-material ratio of the second ball milling is (30-60):1;

[0018] Preferably, the temperature of the second calcination in step (1) is 900° C.-1200° C., and the time of the second calcination is 5 h-8 h;

[0019] Preferably, the ball milling medium of the wet ball milling in step (1) is zirconia ball milling beads, the speed of the wet ball milling is 300 rpm-600 rpm, the time of the wet ball milling is 20 h-40 h, and the ball-to-material ratio of the wet ball milling is (30-60):1;

[0020] Preferably, the mesh size of the sieving in step (1) is 100-300 mesh;

[0021] Preferably, the mass ratio of sodium zirconium silicon phosphorus oxide, methanol and glacial acetic acid in step (1) is (4-8): (30-50): (7-15).

[0022] Furthermore, the concentration of tris(hydroxymethyl)aminomethane in the sodium zirconium silicon phosphorus oxygen solution in step (2) is 2 g L -1 -4g L -1 The concentration of sodium zirconium silicon phosphorus oxygen in the sodium zirconium silicon phosphorus oxygen solution is 100g L -1 -160g L -1 , the pH of the sodium zirconium silicon phosphorus oxygen solution is 7-10;

[0023] Preferably, the mass ratio of sodium zirconium silicon phosphorus oxide to dopamine hydrochloride in step (2) is (3-6):1;

[0024] Preferably, the pH of the polydopamine-coated sodium zirconium silicon phosphorus oxygen solution in step (2) is 7-10, and the concentration of the polydopamine-coated sodium zirconium silicon phosphorus oxygen solution is 80g L -1 -160g L -1 ;

[0025] Preferably, the mass ratio of the polydopamine-coated sodium zirconium silicon phosphorus oxide to bisamino polyethylene glycol in step (2) is (20-50):1.

[0026] In another aspect, the present invention provides a method for preparing any of the above-mentioned organic-inorganic composite solid electrolytes, comprising the following steps:

[0027] Polyethylene glycol, polyvinylidene fluoride, an inorganic ceramic filler and a sodium salt are dissolved in a solvent to obtain a mixed solution, the mixed solution is coated on a substrate, and then vacuum dried to obtain the organic-inorganic composite solid electrolyte.

[0028] Furthermore, the vacuum drying temperature is 50°C-90°C.

[0029] Furthermore, the thickness of the organic-inorganic composite solid electrolyte is 90 μm-130 μm.

[0030] On the other hand, the present invention provides a use of any of the above-mentioned organic-inorganic composite solid electrolytes or an organic-inorganic composite solid electrolyte prepared by any of the above-mentioned preparation methods in a sodium metal battery.

[0031] In another aspect, the present invention provides a sodium metal battery comprising any of the above-mentioned organic-inorganic composite solid electrolytes or an organic-inorganic composite solid electrolyte prepared by any of the above-mentioned preparation methods.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The innovation of the present invention lies in coating the active filler NZSP with PDA and grafting NH2-PEG-NH2, and composite coating with PEO and PVDF, which brings the following advantages: constructing a PVDF / PEO dual polymer system, while improving the flexibility of PVDF, increasing the amorphous region of PEO, thereby taking into account the flexibility and chain segment mobility of the polymer. By coating the surface of the active filler NZSP with PDA and grafting NH2-PEG-NH2 short chains, the compatibility between the filler and the polymer matrix can be effectively improved, thereby significantly inhibiting the agglomeration of the filler. The filler surface modification strategy can also reduce the microscopic interface impedance between the filler and the polymer, activate the ceramic-polymer interface, and then realize the efficient migration of sodium ions through the continuous conduction path inside the ceramic phase, the ceramic-polymer interface and the polymer matrix. The organic-inorganic composite solid electrolyte of the present invention achieved a 3.613×10 -4 S cm -1 High ionic conductivity and excellent galvanostatic cycling stability (at 0.1 mA cm -2 current density can be stably cycled for more than 500 hours). In addition, the organic-inorganic composite solid electrolyte of the present invention has excellent tensile properties, with a tensile strength of 3.38 MPa and an elongation of up to 480%. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of ion transport of the organic-inorganic composite solid electrolyte of the present invention;

[0035] Figure 2 The electrochemical impedance spectroscopy diagrams of the electrolytes prepared in Examples 1-3 and Comparative Examples 1-2 of the present invention are shown;

[0036] Figure 3 This is a SEM image of the organic-inorganic composite solid electrolyte prepared in Example 1 of the present invention;

[0037] Figure 4 This is a stress-strain diagram of the organic-inorganic composite solid electrolyte prepared in Example 1 of the present invention;

[0038] Figure 5 The Na symmetric battery assembled with the organic-inorganic composite solid electrolyte prepared in Example 1 of the present invention was -2 Cycling performance diagram at different current densities. DETAILED DESCRIPTION

[0039] In order to better understand the content of the present invention, the content of the present invention is further described below in conjunction with specific implementation methods, but the protection content of the present invention is not limited to the following embodiments.

[0040] Example 1

[0041] Organic-inorganic composite solid electrolytes, including polydopamine-coated sodium zirconium silicon phosphorus oxygen and then grafted with a short chain of bisamino polyethylene glycol filler (denoted as PDA@NZSP-g-NH2-PEG-NH2), a mixture of polyethylene glycol and polyvinylidene fluoride, and sodium bis(trifluoromethanesulfonyl)imide;

[0042] The mass ratio of polyethylene glycol, polyvinylidene fluoride, inorganic ceramic filler and sodium bis(trifluoromethanesulfonyl)imide is 3:0.75:1.196:1.033.

[0043] The preparation method of the filler of polydopamine coated sodium zirconium silicon phosphorus oxygen and grafted with bisamino polyethylene glycol short chain is as follows: (1) 2.6235g sodium carbonate, 3.69g zirconium dioxide, 1.8g silicon dioxide, 1.8975g ammonium dihydrogen phosphate are added to a ball mill, 530g zirconium oxide ball milling beads are added, and the first ball milling is carried out at 600rpm for 5h; then the ball milled product is placed in an oxygen atmosphere and calcined at 900℃ for 12h; after the calcination is completed, the calcined product is added to the ball mill, 370g oxygen is added, and the mixture is heated to 400℃. The zirconia ball milling beads were subjected to a second ball milling at 600 rpm for 6 hours; the ball milled product was then placed in an oxygen atmosphere and calcined at 1150°C for 6 hours to prepare sodium zirconium silicon phosphate; after the calcination, the calcined product sodium zirconium silicon phosphate was added to a ball mill jar, 40 mL of isopropanol and 320 g of zirconia ball milling beads were added, wet ball milled at 370 rpm for 24 hours and passed through a 200 mesh sieve; the sieved sodium zirconium silicon phosphate was dried and then placed in a beaker, 50 mL of methanol and 10 g of glacial acetic acid were added and stirred for 14 hours;

[0044] (2) The acid-treated sodium zirconium silicon phosphide was centrifuged for 8 minutes, repeated several times and dried, then 5 g of sodium zirconium silicon phosphide was placed in a beaker, 50 mL of methanol, 200 mg of tris(hydroxymethyl)aminomethane and sodium hydroxide (the pH of the solution was adjusted to 8.5) were added, and then 1 g of dopamine hydrochloride was added and stirred for 14 hours to obtain PDA@NZSP; PDA@NZSP was centrifuged for 8 minutes, repeated several times and dried, then 4 g of PDA@NZSP was placed in a beaker, 50 mL of methanol and sodium hydroxide (the pH of the solution was adjusted to 8.5) were added, and then 100 mg of bis(amino)polyethylene glycol was added and stirred for 14 hours for grafting to obtain PDA@NZSP-g-NH2-PEG-NH2.

[0045] The preparation method of the organic-inorganic composite solid electrolyte is as follows: 0.3g PEO, 0.075g PVDF, 0.1196g PDA@NZSP-g-NH2-PEG-NH2 and 0.1033g sodium bis(trifluoromethanesulfonyl)imide are dissolved in 7g DMF, then coated on a PTFE substrate with a scraper, and vacuum dried at 60°C to obtain an organic-inorganic composite solid electrolyte, the mass fraction of PDA@NZSP-g-NH2-PEG-NH2 in the electrolyte is 20%; the thickness of the organic-inorganic composite solid electrolyte is 100μm.

[0046] Example 2

[0047] Organic-inorganic composite solid electrolytes, including polydopamine-coated sodium zirconium silicon phosphorus oxygen and then grafted with a short chain of bisamino polyethylene glycol filler (denoted as PDA@NZSP-g-NH2-PEG-NH2), a mixture of polyethylene glycol and polyvinylidene fluoride, and sodium bis(trifluoromethanesulfonyl)imide;

[0048] The mass ratio of polyethylene glycol, polyvinylidene fluoride, inorganic ceramic filler and sodium bis(trifluoromethanesulfonyl)imide is 3:0.75:2.050:1.033.

[0049] The preparation method of the filler of polydopamine coated sodium zirconium silicon phosphorus oxygen and grafted with bisamino polyethylene glycol short chain is as follows: (1) 2.6235g sodium carbonate, 3.69g zirconium dioxide, 1.8g silicon dioxide, 1.8975g ammonium dihydrogen phosphate are added to a ball mill, 530g zirconium oxide ball milling beads are added, and the first ball milling is carried out at 600rpm for 5h; then the ball milled product is placed in an oxygen atmosphere and calcined at 900℃ for 10h; after the calcination is completed, the calcined product is added to the ball mill, 370g oxygen is added, and the mixture is heated to 400℃. The zirconia ball milling beads were subjected to a second ball milling at 600 rpm for 6 hours; the ball milled product was then placed in an oxygen atmosphere and calcined at 1200°C for 5 hours to prepare sodium zirconium silicon phosphate; after the calcination, the calcined product sodium zirconium silicon phosphate was added to a ball mill jar, 40 mL of isopropanol and 320 g of zirconia ball milling beads were added, wet ball milled at 400 rpm for 20 hours and passed through a 200 mesh sieve; the sieved sodium zirconium silicon phosphate was dried and then placed in a beaker, 50 mL of methanol and 10 g of glacial acetic acid were added and stirred for 13 hours;

[0050] (2) The acid-treated sodium zirconium silicon phosphide was centrifuged for 8 minutes, repeated several times and dried, then 5 g of sodium zirconium silicon phosphide was placed in a beaker, 50 mL of methanol, 200 mg of tris(hydroxymethyl)aminomethane and sodium hydroxide (the pH of the solution was adjusted to 8.5) were added, and then 1 g of dopamine hydrochloride was added and stirred for 13 hours to obtain PDA@NZSP; PDA@NZSP was centrifuged for 8 minutes, repeated several times and dried, then 4 g of PDA@NZSP was placed in a beaker, 50 mL of methanol and sodium hydroxide (the pH of the solution was adjusted to 8.5) were added, and then 100 mg of bis(amino)polyethylene glycol was added and stirred for 13 hours for grafting to obtain PDA@NZSP-g-NH2-PEG-NH2.

[0051] The preparation method of the organic-inorganic composite solid electrolyte is as follows: 0.3g PEO, 0.075g PVDF, 0.2050g PDA@NZSP-g-NH2-PEG-NH2 and 0.1033g sodium bis(trifluoromethanesulfonyl)imide are dissolved in 7g DMF, then coated on a PTFE substrate with a scraper, and vacuum dried at 60°C to obtain an organic-inorganic composite solid electrolyte, the mass fraction of PDA@NZSP-g-NH2-PEG-NH2 in the electrolyte is 30%; the thickness of the organic-inorganic composite solid electrolyte is 110μm.

[0052] Example 3

[0053] Organic-inorganic composite solid electrolytes, including polydopamine-coated sodium zirconium silicon phosphorus oxygen and then grafted with a short chain of bisamino polyethylene glycol filler (denoted as PDA@NZSP-g-NH2-PEG-NH2), a mixture of polyethylene glycol and polyvinylidene fluoride, and sodium bis(trifluoromethanesulfonyl)imide;

[0054] The mass ratio of polyethylene glycol, polyvinylidene fluoride, inorganic ceramic filler and sodium bis(trifluoromethanesulfonyl)imide is 3:0.75:3.189:1.033.

[0055] The preparation method of the filler of polydopamine coated sodium zirconium silicon phosphorus oxygen and grafted with bisamino polyethylene glycol short chain is as follows: (1) 2.6235g sodium carbonate, 3.69g zirconium dioxide, 1.8g silicon dioxide, 1.8975g ammonium dihydrogen phosphate are added to a ball mill, 470g zirconium oxide ball milling beads are added, and the first ball milling is carried out at 600rpm for 5h; then the ball milled product is placed in an oxygen atmosphere and calcined at 900℃ for 10h; after the calcination is completed, the calcined product is added to the ball mill, 400g oxygen is added, and the mixture is heated to 370℃ for 10h. The zirconia ball milling beads were subjected to a second ball milling at 600 rpm for 6 hours; the ball milled product was then placed in an oxygen atmosphere and calcined at 1150°C for 5 hours to prepare sodium zirconium silicon phosphate; after the calcination, the calcined product sodium zirconium silicon phosphate was added to a ball mill jar, 40 mL of isopropanol and 370 g of zirconia ball milling beads were added, wet ball milled at 400 rpm for 24 hours and passed through a 200 mesh sieve; the sieved sodium zirconium silicon phosphate was dried and then placed in a beaker, 50 mL of methanol and 10 g of glacial acetic acid were added and stirred for 16 hours;

[0056] (2) The acid-treated sodium zirconium silicon phosphide was centrifuged for 8 minutes, repeated several times and dried, and then 5 g of sodium zirconium silicon phosphide was placed in a beaker, 50 mL of methanol, 200 mg of tris(hydroxymethyl)aminomethane and NaOH (the pH of the solution was adjusted to 8) were added, and then 1 g of dopamine hydrochloride was added and stirred for 16 hours to obtain PDA@NZSP; PDA@NZSP was centrifuged for 8 minutes, repeated several times and dried, and then 4 g of PDA@NZSP was placed in a beaker, 50 mL of methanol and NaOH (the pH of the solution was adjusted to 8) were added, and then 100 mg of bis(amino)polyethylene glycol was added and stirred for 16 hours for grafting to obtain PDA@NZSP-g-NH2-PEG-NH2;

[0057] The preparation method of the organic-inorganic composite solid electrolyte is as follows: 0.3g PEO, 0.075g PVDF, 0.3189g PDA@NZSP-g-NH2-PEG-NH2 and 0.1033g sodium bis(trifluoromethanesulfonyl)imide are dissolved in 7g DMF, then coated on a PTFE substrate with a scraper, and vacuum dried at 60°C to obtain an organic-inorganic composite solid electrolyte. The mass fraction of PDA@NZSP-g-NH2-PEG-NH2 in the electrolyte is 40%; the thickness of the organic-inorganic composite solid electrolyte is 130μm.

[0058] Comparative Example 1

[0059] Organic-inorganic composite solid electrolytes, including a mixture of polyethylene glycol and polyvinylidene fluoride, and sodium bis(trifluoromethanesulfonyl)imide;

[0060] The mass ratio of polyethylene glycol, polyvinylidene fluoride and sodium bis(trifluoromethanesulfonyl)imide is 3:0.75:1.033.

[0061] The preparation method of the composite solid electrolyte is as follows: 0.3g PEO, 0.075g PVDF and 0.1033g sodium bis(trifluoromethanesulfonyl)imide are dissolved in 7g DMF, then coated on a PTFE substrate with a scraper, and vacuum dried at 60°C to obtain a composite solid electrolyte. The mass fraction of PDA@NZSP-g-NH2-PEG-NH2 in the electrolyte is 0wt%; the thickness of the composite solid electrolyte is 90μm.

[0062] Comparative Example 2

[0063] Organic-inorganic composite solid electrolytes, including polydopamine-coated sodium zirconium silicon phosphorus oxygen and then grafted with a short chain of bisamino polyethylene glycol filler (denoted as PDA@NZSP-g-NH2-PEG-NH2), a mixture of polyethylene glycol and polyvinylidene fluoride, and sodium bis(trifluoromethanesulfonyl)imide;

[0064] The mass ratio of polyethylene glycol, polyvinylidene fluoride, inorganic ceramic filler and sodium salt is 3:0.75:0.531:1.033.

[0065] The preparation method of the filler of polydopamine coated sodium zirconium silicon phosphorus oxygen and grafted with bisamino polyethylene glycol short chain is as follows: (1) 2.6235g sodium carbonate, 3.69g zirconium dioxide, 1.8g silicon dioxide, 1.8975g ammonium dihydrogen phosphate are added to a ball mill, 500g zirconium oxide ball milling beads are added, and the first ball milling is carried out at 500rpm for 5h; then the ball milled product is placed in an oxygen atmosphere and calcined at 1000℃ for 10h; after the calcination is completed, the calcined product is added to the ball mill, 430g oxygen is added, and the mixture is heated to 1000℃ for 10h. The zirconia ball milling beads were subjected to a second ball milling at 500 rpm for 6 hours; the ball milled product was then placed in an oxygen atmosphere and calcined at 1150°C for 10 hours to prepare sodium zirconium silicon phosphate; after the calcination, the calcined product sodium zirconium silicon phosphate was added to a ball mill jar, 40 mL of isopropanol and 350 g of zirconia ball milling beads were added, wet ball milled at 370 rpm for 24 hours and passed through a 200 mesh sieve; the sieved sodium zirconium silicon phosphate was dried and then placed in a beaker, 50 mL of methanol and 10 g of glacial acetic acid were added and stirred for 15 hours;

[0066] (2) The acid-treated sodium zirconium silicon phosphide was centrifuged for 8 minutes, repeated several times and dried, then 5 g of sodium zirconium silicon phosphide was placed in a beaker, 50 mL of methanol, 200 mg of tris(hydroxymethyl)aminomethane and NaOH (the pH of the solution was adjusted to 9) were added, and then 1 g of dopamine hydrochloride was added and stirred for 15 hours to obtain PDA@NZSP; PDA@NZSP was centrifuged for 8 minutes, repeated several times and dried, then 4 g of PDA@NZSP was placed in a beaker, 50 mL of methanol and sodium hydroxide (the pH of the solution was adjusted to 9) were added, and then 100 mg of bisamino polyethylene glycol was added and stirred for 15 hours for grafting to obtain PDA@NZSP-g-NH2-PEG-NH2.

[0067] The preparation method of the organic-inorganic composite solid electrolyte is as follows: 0.3g PEO, 0.075g PVDF, 0.0531g PDA@NZSP-g-NH2-PEG-NH2 and 1.033g sodium bis(trifluoromethanesulfonyl)imide are dissolved in 7g DMF, then coated on a PTFE substrate with a scraper, and vacuum dried at 60°C to obtain an organic-inorganic composite solid electrolyte. The mass fraction of PDA@NZSP-g-NH2-PEG-NH2 in the electrolyte is 10%; the thickness of the organic-inorganic composite solid electrolyte is 100μm.

[0068] The ion transport schematic diagram of the organic-inorganic composite solid electrolyte of the present invention is as follows Figure 1 As shown, from Figure 1 It can be seen that PDA@NZSP-g-NH2-PEG-NH2 forms a fast Na + transport channel, which is beneficial to Na +Rapid migration between positive and negative electrodes.

[0069] The electrolytes prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to ionic conductivity tests: stainless steel symmetrical cells were assembled, and the ionic conductivity (σ) of the electrolytes was measured using electrochemical impedance spectroscopy (EIS). The EIS test used CHI760E and CHI650E electrochemical workstations (Shanghai Zhenhua Instrument Co., Ltd.), with a frequency range of 1000kHz to 0.01Hz and an AC amplitude of 10mV. The calculation formula for ionic conductivity is: σ=L / (R*S). Wherein L is the thickness of the electrolyte membrane, S is the area of ​​the stainless steel sheet electrode, and R is the bulk resistance. The electrochemical impedance spectrum is shown in the figure below. Figure 2 The ionic conductivity results are shown in Table 1.

[0070] Table 1 Ionic conductivity of electrolytes prepared in Examples 1-3 and Comparative Examples 1-2

[0071] <![CDATA[PDA@NZSP-g-NH2-PEG-NH2 content (%)]]> <![CDATA[Ionic conductivity (S cm -1 )]]> Comparative Example 1 0 <![CDATA[1.311×10 -4 ]]> Comparative Example 2 10 <![CDATA[1.270×10 -4 ]]> Example 1 20 <![CDATA[3.613×10 -4 ]]> Example 2 30 <![CDATA[2.330×10 -4 ]]> Example 3 40 <![CDATA[1.918×10 -4 ]]>

[0072] As can be seen from Table 1, when the content of PDA@NZSP-g-NH2-PEG-NH2 is 20%, 30% and 40%, the ionic conductivity is higher than that of the pure polymer system (1.311×10 -4 S cm -1 ), the ionic conductivity is improved, and when the content of PDA@NZSP-g-NH2-PEG-NH2 is 20%, the ionic conductivity reaches 3.613×10 -4 S cm -1 , which is much higher than that of pure polymer system (1.311×10 -4 S cm -1 ), indicating that the addition of PDA@NZSP-g-NH2-PEG-NH2 successfully improved the performance of the electrolyte.

[0073] The organic-inorganic composite solid electrolyte prepared in Example 1 was scanned by electron microscope, and the results were as follows: Figure 3 As shown. Figure 3 It can be seen that the surface of the electrolyte is flat and smooth, and PDA@NZSP-g-NH2-PEG-NH2 is evenly distributed in the electrolyte without obvious agglomeration.

[0074] The tensile properties of the organic-inorganic composite solid electrolyte prepared in Example 1 were tested. Figure 4 As shown. Figure 4 It can be seen that the tensile strength of the electrolyte reaches 3.4 MPa and the elongation at break reaches 480%.

[0075] The Na symmetric battery assembled with the organic-inorganic composite solid electrolyte prepared in Example 1 was tested at 0.1 mA cm-2 The cycling performance under current density was tested, and the results were as follows Figure 5 As shown. Figure 5 It can be seen that the battery can be stably cycled for more than 540h at room temperature, and a stable SEI film is formed on the surface of the electrolyte, which can promote the Na + The uniform deposition has good interface stability and resistance to sodium dendrite penetration.

[0076] In summary, the organic-inorganic composite solid electrolyte of the present invention is composed of a two-component polymer (PEO and PVDF) and a modified active filler (PDA@NZSP-g-NH2-PEG-NH2). By constructing a PVDF / PEO dual polymer system, the flexibility of PVDF is improved while the amorphous region of PEO is increased, thereby taking into account both the flexibility of the polymer and the chain segment mobility. 12 , NZSP) surface coated with polydopamine (PDA) and grafted with NH2-PEG-NH2 short chains can effectively improve the compatibility between the filler and the polymer matrix, thereby significantly inhibiting filler agglomeration. The filler surface modification strategy can also reduce the microscopic interfacial impedance between the filler and the polymer, activate the ceramic-polymer interface, and achieve efficient sodium ion migration through a continuous conduction path within the ceramic phase, at the ceramic-polymer interface, and within the polymer matrix. Therefore, the organic-inorganic composite solid electrolyte prepared by the present invention has high ionic conductivity, good mechanical properties, and good interfacial stability.

[0077] The above description is only a specific embodiment of the present invention, not all embodiments. Any equivalent transformation of the technical solution of the present invention made by ordinary technicians in this field after reading the specification of the present invention is covered by the claims of the present invention.

Claims

1. An organic-inorganic composite solid electrolyte comprising an inorganic ceramic filler, a polymer matrix, and a sodium salt; The inorganic ceramic filler is a filler formed by coating sodium zirconium silicon phosphorus oxygen with polydopamine and then grafting a short chain of bisamino polyethylene glycol; The polymer base is a mixture of polyethylene glycol and polyvinylidene fluoride.

2. The organic-inorganic composite solid electrolyte according to claim 1, characterized in that The mass ratio of the polyethylene glycol, polyvinylidene fluoride, inorganic ceramic filler and sodium salt is 3: (0.5-1): (0.6-4): (1-1.5).

3. The organic-inorganic composite solid electrolyte according to claim 1, characterized in that The sodium salt is at least one of sodium bis(trifluoromethanesulfonyl)imide, sodium trifluoromethanesulfonate, sodium hexafluorophosphate, and sodium perchlorate.

4. The organic-inorganic composite solid electrolyte according to claim 1, characterized in that The preparation method of the inorganic ceramic filler is: (1) ball-milling sodium carbonate, zirconium dioxide, silicon dioxide and ammonium dihydrogen phosphate for the first time, and then calcining the ball-milled product for the first time in an oxygen atmosphere; after the calcination, ball-milling the calcined product for the second time, and then calcining the ball-milled product for the second time in an oxygen atmosphere to prepare sodium zirconium silicon phosphorus oxide; after the calcination, wet-ball-milling the calcined product sodium zirconium silicon phosphorus oxide and sieving it, drying the sieved sodium zirconium silicon phosphorus oxide, and then adding methanol and glacial acetic acid and stirring for 12 hours to 16 hours; (2) The acid-treated sodium zirconium silicon phosphide is centrifuged and dried, and then methanol, trishydroxymethylaminomethane and sodium hydroxide are added to obtain a sodium zirconium silicon phosphide solution, and then dopamine hydrochloride is added and stirred for 12h-16h to obtain polydopamine-coated sodium zirconium silicon phosphide; methanol and sodium hydroxide are added to the polydopamine-coated sodium zirconium silicon phosphide to obtain a polydopamine-coated sodium zirconium silicon phosphide solution, and then bisamino polyethylene glycol is added and stirred for 12h-16h for grafting to prepare an inorganic ceramic filler.

5. The organic-inorganic composite solid electrolyte according to claim 4, characterized in that The mass ratio of sodium carbonate, zirconium dioxide, silicon dioxide and ammonium dihydrogen phosphate in step (1) is 2.6235:3.69:1.8:1.8975; Preferably, the ball milling medium used in the first ball milling in step (1) is zirconia ball milling beads, the speed of the first ball milling is 500 rpm-800 rpm, the time of the first ball milling is 5 h-8 h, and the ball-to-material ratio of the first ball milling is (30-60):1; Preferably, the temperature of the first calcination in step (1) is 800° C.-1100° C., and the time of the first calcination is 10 h-30 h; Preferably, the ball milling medium for the second ball milling in step (1) is zirconia ball milling beads, the speed of the second ball milling is 500 rpm-800 rpm, the time of the second ball milling is 5 h-8 h, and the ball-to-material ratio of the second ball milling is (30-60):1; Preferably, the temperature of the second calcination in step (1) is 900° C.-1200° C., and the time of the second calcination is 5 h-8 h; Preferably, the ball milling medium of the wet ball milling in step (1) is zirconia ball milling beads, the speed of the wet ball milling is 300 rpm-600 rpm, the time of the wet ball milling is 20 h-40 h, and the ball-to-material ratio of the wet ball milling is (30-60):1; Preferably, the mesh size of the sieving in step (1) is 100-300 mesh; Preferably, the mass ratio of sodium zirconium silicon phosphorus oxide, methanol and glacial acetic acid in step (1) is (4-8): (30-50): (7-15).

6. The organic-inorganic composite solid electrolyte according to claim 4, characterized in that The concentration of tris(hydroxymethyl)aminomethane in the sodium zirconium silicon phosphorus oxygen solution in step (2) is 2 g L -1 -4g L -1 The concentration of sodium zirconium silicon phosphorus oxygen in the sodium zirconium silicon phosphorus oxygen solution is 100g L -1 -160g L -1 , the pH of the sodium zirconium silicon phosphorus oxygen solution is 7-10; Preferably, the mass ratio of sodium zirconium silicon phosphorus oxide to dopamine hydrochloride in step (2) is (3-6):1; Preferably, the pH of the polydopamine-coated sodium zirconium silicon phosphorus oxygen solution in step (2) is 7-10, and the concentration of the polydopamine-coated sodium zirconium silicon phosphorus oxygen solution is 80g L -1 -160g L -1 ; Preferably, the mass ratio of the polydopamine-coated sodium zirconium silicon phosphorus oxide to bisamino polyethylene glycol in step (2) is (20-50):

1.

7. The method for preparing the organic-inorganic composite solid electrolyte according to any one of claims 1 to 6, characterized in that: The following steps are involved: Polyethylene glycol, polyvinylidene fluoride, an inorganic ceramic filler and a sodium salt are dissolved in a solvent to obtain a mixed solution, the mixed solution is coated on a substrate, and then vacuum dried to obtain the organic-inorganic composite solid electrolyte.

8. The preparation method according to claim 7, characterized in that The vacuum drying temperature is 50°C-90°C; Preferably, the thickness of the organic-inorganic composite solid electrolyte is 90 μm-130 μm.

9. Use of the organic-inorganic composite solid electrolyte according to any one of claims 1 to 6 or the organic-inorganic composite solid electrolyte prepared by the preparation method according to any one of claims 7 to 8 in a sodium metal battery.

10. A sodium metal battery, characterized in that: The invention comprises the organic-inorganic composite solid electrolyte according to any one of claims 1 to 6 or the organic-inorganic composite solid electrolyte prepared by the preparation method according to any one of claims 7 to 8.

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