Double Na ion channel modified solid electrolyte, preparation method and application thereof, and solid sodium battery

Abstract

The invention belongs to the field of electrolytes, and particularly relates to a double Na ion channel modified solid electrolyte, a preparation method and application thereof and a solid sodium battery, the electrolyte comprises a polymer matrix and a functional material dispersed in the polymer matrix; the polymer matrix comprises PEO (Polyethylene Oxide) and succinonitrile grafted with halogen anions; the functional material is C2 / c in-phase NZSPX (at) NVP, and comprises a core of Na3V2 (PO4) 3 of a C2 / c phase and a shell of Na3Zr2-nXnSi2PO12 of a C2 / c phase, wherein the surface of the core is coated with the shell of Na3Zr2-nXnSi2PO12; x is at least one of Ti, Hf, Nb, Ta, Mo, Cr and Sc, and n ranges from 0.1 to 0.6. According to the invention, PEO and halogen anion grafted succinonitrile are innovatively combined as a polymer matrix, and are further matched with a special C2 / c in-phase NZSPX at NVP functional material, so that synergism can be realized based on the special heterogeneous in-phase and coating characteristics of the functional material and the combination of the combined polymer matrix, and the impedance of the material can be reduced; and the fast charge and long cycle stability of the material are improved.

Description

Technical Field

[0001] This invention belongs to the field of sodium-ion batteries, specifically relating to the field of solid electrolytes for sodium-ion batteries. Background Technology

[0002] Currently, the main challenges to the widespread adoption of solid-state sodium-ion batteries are unsatisfactory actual energy density and poor cycle stability. The key to solving these problems lies in technological breakthroughs in solid-state electrolyte materials. In solid-state batteries, the liquid electrolyte is replaced by a lighter solid electrolyte, eliminating the separator between the positive and negative electrodes, reducing overall weight, and thus increasing its theoretical energy density. However, in practical applications, the electrochemical performance of solid-state electrolytes has not yet reached ideal levels, and the relatively high electrode / electrolyte interface resistance causes additional voltage losses, resulting in actual energy densities far lower than expected, failing to achieve the theoretical advantages compared to liquid batteries.

[0003] Solid electrolytes, as key materials in solid-state sodium-ion batteries, should possess high room-temperature ion mobility (>10). -4 S / cm). In recent years, polyethylene oxide (PEO) and sodium superionic conductor (NASICON) Na3Zr2Si2PO4 have been used in research. 12 Solid electrolytes combining NZSP have received considerable attention and research. PEO exhibits high electrochemical stability and low interfacial resistance with the electrode, while NZSP demonstrates high ion mobility (10⁻⁶). -4 ~ 10 -3 Existing studies have shown that when the mass ratio of NZSP to PEO is 2:3, the ion mobility can reach 6.5 × 10⁻⁶. -5 S / cm. However, in actual preparation, NZSP filler tends to aggregate in the PEO substrate and has poor interfacial compatibility with PEO. This phenomenon leads to a high migration barrier for Na ions at the PEO / NZSP interface, resulting in a significant "barrel effect" that limits the theoretical advantages of the PEO / NZSP composite electrolyte. Therefore, designing a highly compatible PEO / NZSP interface structure to achieve rapid diffusion of Na ions at this interface and improve the overall ion mobility of the composite electrolyte has become a key scientific problem in solving the "barrel effect".

[0004] On the other hand, solid-state sodium-ion batteries suffer from significant voltage loss due to the excessively slow migration of Na ions at the electrode / electrolyte interface, resulting in substantial polarization. While flexible polymer substrates can mitigate the interface problem to some extent, their interfacial impedance remains far higher than that of liquid electrolytes, which can completely wet the electrode surface. Furthermore, compared to the negative electrode / electrolyte interface, the repeated insertion and extraction of Na ions during charging and discharging in the positive electrode causes significant volume changes, substantially increasing the contact resistance with the electrolyte. This results in a large migration barrier for Na ions at the interface, leading to a gradual decrease in the positive electrode capacity.

[0005] In summary, there is an urgent need to construct a solid electrolyte with excellent comprehensive electrochemical performance, improve ionic conductivity and alleviate the cathode / electrolyte interface impedance problem, thereby enhancing the actual energy density and cycle life of solid sodium-ion batteries. Summary of the Invention

[0006] To address the problems of the prior art, the primary objective of this invention is to provide a solid electrolyte modified with dual Na ion channels, aiming to obtain a solid electrolyte material with excellent fast charging and cycle stability.

[0007] The second objective of this invention is to provide a method for preparing the dual Na ion channel modified solid electrolyte and its application in solid sodium ion batteries.

[0008] A third objective of this invention is to provide a solid sodium-ion battery comprising the aforementioned dual Na-ion channel modified solid electrolyte.

[0009] A dual Na ion channel modified solid electrolyte comprises a polymer matrix and a functional material dispersed in the polymer matrix; the polymer matrix comprises PEO and succinate grafted with halogen anions.

[0010] The functional material is a C2 / c in-phase NZSPX@NVP, which comprises a core of Na3V2(PO4)3 in the C2 / c phase, and Na3Zr in the C2 / c phase coated on the surface of the core. 2-n Si2PO 12 X n The shell; wherein X is at least one of Ti, Hf, Nb, Ta, Mo, Cr, and Sc, and n is 0.1 to 0.6.

[0011] This invention innovatively uses PEO and halogen anion-grafted succinate as a polymer matrix, and further combines it with the special C2 / c homogeneous NZSPX@NVP functional material. Based on the special heterogeneous homogeneous and encapsulation characteristics of the functional material and the combination of the polymer matrix, synergy can be achieved, which can reduce the impedance of the material and improve the fast charging and long cycle stability of the material.

[0012] In this invention, X is preferably Ti. Preferred X provides better fast charging and long-cycle stability.

[0013] In this invention, n is preferably 0.3 to 0.5; more preferably 0.35 to 0.45. These preferred ratios result in better fast charging and long-cycle stability.

[0014] In this invention, the halogen anion in the halogen-grafted succinate in the polymer matrix is ​​at least one selected from fluorine, bromine, chlorine, and iodine, and more preferably fluorine. The preferred fluorine-grafted succinate provides superior fast-charging and long-cycle stability.

[0015] Preferably, the weight ratio of PEO to halogen anion-grafted succinate is 2:0.5~1.5; more preferably 2:1~1.4; and even more preferably 2:1.1~1.3.

[0016] Preferably, in NZSPX@NVP, the molar ratio of NVP to NZSPX can be 1~3:1; more preferably, it can be 1.5~2.5:1. The core particle size is 80~120nm; the shell thickness is 40~60nm;

[0017] Preferably, in the dual Na ion channel modified solid electrolyte, the weight ratio of PEO to functional material is 2:1~3; more preferably 2:1.2~2; and even more preferably 2:1.5~1.7.

[0018] This invention also provides a method for preparing a solid electrolyte modified with dual Na ion channels, comprising the following steps:

[0019] Step 1: Preparation of functional materials

[0020] The NVP material with C2 / c phase was obtained. The NVP material, the precursor raw material for synthesizing NZSPX and the co-modifier were mixed in liquid phase and dried. Then, the mixture was calcined to construct the same phase NZSPX on the NVP, thus obtaining the functional material.

[0021] The combined modifiers include Formula 1 and Formula 2;

[0022] Formula 1;

[0023] Formula 2;

[0024] The R1 mentioned is a carboxyl group, C1~C1. 10 Alkyl or substituted alkyl; A is a carboxylate, sulfonate or sulfate group; substituted alkyl is a group having at least one substituent, either a hydroxyl or a carboxyl group, on an alkyl chain from C1 to C6;

[0025] R2 is C6~C 20 The alkyl group; R3 is a C1~C3 alkyl group;

[0026] B - It is a halide anion;

[0027] Step 2: Preparation of solid electrolyte

[0028] The solid electrolyte is prepared by mixing functional materials and a polymer matrix.

[0029] The difficulty in preparing the material described in this invention lies in how to construct the C2 / c homogeneous NZSPX@NVP. This is because the phases of NVP and NZSPX are diverse, and the construction conditions for NZSPX and NVP phases differ significantly, making it difficult to achieve selective construction and coating of the core-shell C2 / c heterogeneous homogeneous phase during NZSPX sintering. To address this technical problem, this invention innovatively employs a combined modifier assisted by Formulas 1 and 2 for the coating process. Furthermore, the use of X allows for artificial control of the NZSPX phase, enabling efficient and selective adaptation with the NVP phase. This reduces the interface of the coating structure and lowers the interfacial impedance. Combined with the composite polymer matrix, this further enhances the fast-charging and long-cycle stability of the solid electrolyte.

[0030] In this invention, the C2 / c phase NVP material can be prepared based on known methods. For example, as an optional approach, the preparation steps are as follows: a vanadium source and a ligand are subjected to a hydrothermal coordination reaction to obtain a V-MOF framework material, and then the V-MOF framework material is subjected to a first-stage calcination treatment, followed by a second-stage calcination treatment after mixing with a phosphorus source and a sodium source to obtain the C2 / c phase NVP material.

[0031] The vanadium source is at least one of vanadium oxides and water-soluble salts.

[0032] The ligands include at least one of 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, isophthalic acid and its derivatives, 4,4-stilbene dicarboxylic acid or 2-methylimidazole.

[0033] The molar ratio of vanadium to ligand in the vanadium source is 1:0.5~2.5, which can be further 1:1~2; and even further 1:1.4~1.5.

[0034] The temperature for hydrothermal coordination reactions is 100~200℃, and can be further increased to 170~190℃.

[0035] The hydrothermal coordination reaction takes 12-18 hours, and can be further extended to 14-16 hours.

[0036] The phosphorus source includes at least one cation selected from Na and ammonium, and a compound containing at least one anion selected from phosphate, hydrogen phosphate, and dihydrogen phosphate.

[0037] Sodium sources include at least one of sodium oxides, hydroxides, carbonates, bicarbonates, carboxylates, chlorides, nitrates, and acetates.

[0038] The molar ratio of Na:V:P is 3:2:3.

[0039] In this invention, the temperature of the first calcination stage is 400~500℃.

[0040] Preferably, the calcination time for the first stage is 3 to 5 hours.

[0041] Preferably, the temperature of the second calcination stage is 600~800℃; more preferably, it is 650~750℃. At the preferred temperature, better fast charging and long-cycle stability can be obtained.

[0042] Preferably, the second calcination time is 12-18 hours, and more preferably 14-16 hours.

[0043] In this invention, in step 1, the precursor materials for synthesizing NZSPX include sodium source, phosphorus source, zirconium source, silicon source and X source in stoichiometric proportions.

[0044] In this invention, as an optional option, the sodium source is at least one of sodium oxide, hydroxide, carbonate, bicarbonate, phosphate, hydrogen phosphate, and dihydrogen phosphate.

[0045] The phosphorus source includes at least one cation selected from Na and ammonium, and a compound containing at least one anion selected from phosphate, hydrogen phosphate, and dihydrogen phosphate.

[0046] The zirconium source is at least one of zirconium nitrate and zirconium oxychloride.

[0047] The silicon source silicate, silicate ester, and other components may be, for example, at least one of tetraethyl orthosilicate, ammonium silicate, sodium silicate, sodium persilicate, and sodium metasilicate.

[0048] The X source is an electrochemically inactive metal ion containing metal ions X (with ionic radii close to Zr / V, including Ti). 4+ Hf 4+ Nb 4+ Ta 4+ Mo 4+ Cr 3+ ,Sc 3+ At least one of the soluble chemical reagents.

[0049] In this invention, n is 0.1~0.6; preferably 0.3~0.5; more preferably 0.35~0.45. These preferred ratios result in better fast charging and long-cycle stability.

[0050] Preferably, in Formula 1, A is a carboxylate group, and R1 is a carboxyl group or a C1-C3 substituted alkyl group; the substituents in the substituted alkyl group include at least one of hydroxyl and carboxyl groups;

[0051] In Equation 2, R2 is C8~C 14 Straight-chain alkyl groups;

[0052] Preferably, the molar ratio of NZSPX, Formula 1, and Formula 2 is 1:1~10:1~10; further, it can be 1:1~5:1~4; even further, it can be 1:2~4:1~3; most preferably, it is 1:2.5~3.5:1.5~2.5.

[0053] Preferably, the solvent for liquid-phase mixing includes at least one of water and C1-C4 alcohols.

[0054] In this invention, the roasting process includes two roasting stages, wherein the temperature of the first roasting stage is 600~800℃ and the temperature of the second roasting stage is 800~1000℃; preferably, the temperature of the first roasting stage is 650~750℃ and the temperature of the second roasting stage is 850~950℃; the preferred ratio can obtain better fast charging and long cycle stability.

[0055] Preferably, the first roasting time is 24-36 hours; the second roasting time is 6-10 hours. Preferably, the first roasting time is 29-31 hours; the second roasting time is 7-9 hours.

[0056] In this invention, the preparation steps of halogen anion-grafted succinate are as follows: succinic acid and sodium halide are mixed evenly and heated to a molten state in an inert gas, then ammonia plasma is introduced for a certain time, and then cooled to room temperature; the cooled product is mixed evenly with phosphorus pentoxide, and heated to a certain temperature and held for a certain time in a vacuum environment to obtain halogen anion-grafted succinate.

[0057] In this invention, the molar ratio of succinic acid to sodium halide is 1:0.5~2; preferably 1:0.9~1.1. This preferred ratio provides better fast charging and long-cycle stability.

[0058] The treatment time for ammonia plasma can be 10-60 seconds, and can be further reduced to 30-50 seconds.

[0059] In this invention, the molar ratio of succinic acid to phosphorus pentoxide can be 1~10:1; more specifically 3~5:1.

[0060] In this invention, the heat preservation temperature under vacuum is 220~280℃. The heat preservation time can be 5~10 hours.

[0061] Preferably, in the polymer matrix, the weight ratio of ether oxygen bonds in PEO to halogen anion-grafted succinate is 2:0.5~1.5, and more preferably 2:1~1.4;

[0062] Preferably, the weight ratio of PEO to functional material is 2:1~3; more preferably 2:1.2~2; and even more preferably 2:1.5~1.7. These preferred ratios result in better fast charging and long-cycle stability.

[0063] This invention also provides an application of the aforementioned dual Na ion channel modified solid electrolyte, using it as a solid electrolyte to prepare solid sodium ion batteries.

[0064] The present invention also provides a solid sodium-ion battery comprising the aforementioned dual Na-ion channel modified solid electrolyte.

[0065] Beneficial effects:

[0066] This invention innovatively employs a combination of modifiers, assisted by Formulas 1 and 2, for the coating process. Furthermore, the use of X allows for the artificial control of the NZSPX phase, enabling efficient and selective compatibility with the NVP phase. This reduces the interface of the coating structure and lowers the interfacial impedance. Combined with the composite polymer matrix, this further enhances the fast-charging and long-cycle stability of the solid electrolyte.

[0067] The solid electrolyte described in this invention exhibits a strong coordination effect between the polymer matrix and the NZSPX@NVP cations and anions, enabling the construction of a low-resistance organic-inorganic complex phase interface transport layer. This not only enhances the migration rate of sodium ions at the NZSP / PEO interface but also forms a dual Na ion transport channel through the C2 / c phase interface and cation-anion coordination in the NZSPX@NVP core-shell structure. The conventional transport channel transports Na ions through the amorphous PEO phase and the NZSP surface, while the rapid transport channel achieves rapid Na ion hopping through the organic-inorganic complex phase interface constructed by the NZSPX@NVP phase interface and cation-anion coordination. This dual-channel design significantly improves the ionic conductivity of the solid electrolyte and further enhances the actual energy density of the full cell, providing a new approach for developing high-performance solid-state sodium-ion batteries. Attached Figure Description

[0068] Figure 1Scanning electron microscope images of the spherical NVP cathode material, core-shell NZSPT@NVP inorganic filler, and PEO / NZSPT@NVP solid electrolyte prepared in Example 1;

[0069] Figure 2 Transmission electron microscopy image of the core-shell NZSPT@NVP inorganic filler in Example 1;

[0070] Figure 3 X-ray diffraction pattern of the spherical NVP cathode material prepared in Example 1, and the core-shell NZSPT@NVP inorganic filler.

[0071] Figure 4 Comparison of Fourier transform infrared spectra of SN-F, SN, and NaF prepared in Example 1;

[0072] Figure 5 The impedance comparison graphs show the PEO / NZSPT@NVP solid electrolyte and pure PEO film prepared in Example 1.

[0073] Figure 6 Comparison of 0.5C charge-discharge tests of sodium-ion batteries assembled with pure PEO films, using the PEO / NZSPT@NVP solid electrolyte prepared in Example 1 and the NZSPT / PEO solid electrolyte prepared in Comparative Example 4.

[0074] Figure 7 Comparison of cycling tests between the NZSPT@NVP / PEO solid electrolyte prepared in Example 1 and the pure PEO film;

[0075] Figure 8 Scanning electron microscope image of the core-shell NZSPT@NVP inorganic filler prepared for Comparative Example 1;

[0076] Figure 9 Scanning electron microscope image of the core-shell NZSPT@NVP inorganic filler prepared for Comparative Example 1;

[0077] Figure 10 X-ray diffraction pattern of the core-shell NZSPT@NVP inorganic filler prepared for Comparative Example 5. Detailed Implementation

[0078] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The olefin gases used in the specific embodiments should be understood as some examples of the present invention. All specific process parameters and suitable flow battery systems in the embodiments are only examples within a suitable range. That is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not limited to the specific values ​​of the examples above. All graphene nanosheet modified carbon-based electrode materials prepared using the method of the present invention are within the scope of the present invention and should not be construed as limiting the scope of the present invention.

[0079] The present invention discloses a method for preparing an optional dual Na ion channel modified solid electrolyte (also referred to in this invention as a dual Na ion channel NZSPX@NVP / PEO solid electrolyte), comprising the following steps:

[0080] Step 1: Weigh out a certain amount of vanadium pentoxide and oxalic acid, dissolve them in water, and stir to evaporate the water. Then add a certain amount of ethanol and stir to dissolve. Add an appropriate amount of organic ligand and stir to obtain a blue transparent solution. Transfer the solution to a polytetrafluoroethylene-lined reactor and perform a hydrothermal reaction for a period of time. Finally, filter, wash with ethanol, and dry to obtain the brown V-MOF product.

[0081] Step 2: The V-MOF obtained in Step 1 is calcined in an inert gas at a certain temperature for a certain time. Then, the product is dissolved in ethanol with sodium and phosphorus sources in stoichiometric ratios, the solvent is dried by stirring, and the product is thoroughly dried in an oven to obtain the NVP precursor. Subsequently, it is dispersed by hand grinding, calcined in an inert gas at a certain temperature for a certain time, and then sieved through a 400-mesh sieve to obtain spherical sodium vanadium phosphate Na3V2(PO4)3 (NVP) cathode material.

[0082] Step 3: Dissolve the NVP cathode material from Step 2 with sodium, zirconium, silicon, X, and phosphorus sources (in stoichiometric ratios) in a mixed solution of ethanol and water. Stir and dry the solvent, then thoroughly dry in an oven to obtain a core-shell NZSPX@NVP precursor. Subsequently, calcine it in an inert gas at two different temperatures for a certain time to obtain the core-shell NZSPX@NVP inorganic filler.

[0083] Step 4: Weigh a certain mass of succinic acid and sodium halide (NaY), mix them evenly, and heat them to a molten state in an inert gas atmosphere. After holding the mixture at this temperature for a certain time, continuously introduce ammonia plasma for a certain time, and then cool it to room temperature. Mix the cooled product evenly with phosphorus pentoxide, and heat it to a certain temperature in a vacuum environment and hold it for a certain time to obtain succinic anion Y-grafted succinic anion (SN-Y).

[0084] Step 5: Add the NZSPX@NVP inorganic filler obtained in Step 3 to an appropriate amount of acetonitrile solvent, sonicate it to disperse it evenly, then add an appropriate amount of PEO and SN-Y obtained in Step 4, stir at room temperature to dissolve it completely, cast the resulting transparent slurry into a polytetrafluoroethylene mold, heat it in a vacuum environment and keep it at that temperature to completely evaporate the solvent, and obtain PEO / NZSPX@NVP solid electrolyte.

[0085] Further, in step 1, the molar ratio of vanadium pentoxide to oxalic acid is 1:2~4; the amount of ethanol is controlled so that the concentration of vanadium pentoxide is 2~4 mM; the organic ligand includes 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, isophthalic acid and its derivatives, 4,4-stilbene dicarboxylic acid or 2-methylimidazole, wherein 1,4-naphthalenedicarboxylic acid is preferred, and its molar ratio with vanadium pentoxide is 1:0.5~2.5; the hydrothermal reaction temperature is 180±20℃, and the time is 12~18h.

[0086] Further, in step 2, the calcination temperature of the V-MOF is 400~500℃, and the calcination time is 3~5h; the sodium source includes sodium carbonate and sodium dihydrogen phosphate, and the phosphorus source includes diammonium hydrogen phosphate and sodium dihydrogen phosphate, wherein sodium dihydrogen phosphate is preferred (sodium and phosphorus sources can be provided simultaneously); the stoichiometric ratio is controlled to Na:V:P=3:2:3; the calcination temperature of the gel is 600~800℃, and the calcination time is 12~18h.

[0087] Further, in step 3, the sodium source includes at least one of sodium carbonate and sodium dihydrogen phosphate, the zirconium source is zirconium oxychloride or zirconium nitrate, preferably zirconium oxychloride, and the X source is an electrochemically inactive metal ion containing metal ion X (close to the Zr / V ionic radius, including Ti). 4+ Hf 4+ Nb 4+ Ta 4+ Mo 4+ Cr 3+ ,Sc 3+ At least one of the soluble chemical reagents, wherein the reagent contains Ti 4+The optimal source (tetraethyl orthosilicate) is tetraethyl orthosilicate, ammonium silicate, sodium silicate, sodium persilicate, and sodium metasilicate, with tetraethyl orthosilicate being preferred. The phosphorus source includes diammonium hydrogen phosphate and sodium dihydrogen phosphate, with sodium dihydrogen phosphate being preferred (sodium and phosphorus sources can be provided simultaneously). The stoichiometric ratio is controlled as Na:Zr:X:Si:P:Equation 1:Equation 2=3:2−x:x (x=0.1~0.6):2:1:1~5:1~4, and the ratio of water to ethanol is 1:1~3. The first stage calcination temperature of the core-shell NZSPX@NVP precursor is 600~800℃, and the calcination time is 24~36h. The second stage calcination temperature is 800~1000℃, and the calcination time is 6~10h.

[0088] Further, in step 4, the NaY includes sodium fluoride, sodium bromide, sodium chloride, and sodium iodide, with sodium fluoride being preferred. The stoichiometric ratio of succinic acid to NaY is controlled to be 1:0.5~2; preferably 1:0.9~1.1. The heating temperature is 150~200℃, the holding time is 20~40min, and the ammonia plasma is introduced for 20~60s. The stoichiometric ratio of the product to phosphorus pentoxide is controlled to be 3~5:1, the heating temperature is 220~280℃, and the holding time is 5~10h.

[0089] Further, in step 5, the weight ratio of PEO to halogen anion-grafted succinate is 2:0.5~1.5, and the weight ratio of PEO to functional material is 2:1~3; preferably 2:1.2~2; more preferably 2:1.5~1.7; wherein the molecular weight of PEO needs to be greater than or equal to 600,000, and the amount of acetonitrile solvent can be adjusted according to the molecular weight of PEO to ensure that all products are soluble and the resulting slurry has a certain fluidity.

[0090] Example 1

[0091] The preparation method and application of NZSPT@NVP / PEO solid electrolyte with dual Na ion channels include the following steps:

[0092] (1) Weigh 1 mmol of vanadium pentoxide and 3 mmol of oxalic acid and dissolve them in 15 mL of water. Stir at 100 °C to evaporate the water. Then, dissolve the solution in 400 mL of ethanol and add 3 mmol of 1,4-naphthalenedicarboxylic acid. Stir at 40 °C to obtain a blue transparent solution. Transfer the solution to a polytetrafluoroethylene-lined reactor and hydrothermally react at 180 °C for 15 h. Finally, filter the solution, wash it three times with ethanol, and dry it to obtain the brown V-MOF product.

[0093] (2) The V-MOF was calcined in Ar at 450±10℃ for 4h. Then the product was dissolved with 3mmol sodium dihydrogen phosphate in 50mL ethanol, the solvent was dried by stirring at 60℃, and the product was thoroughly dried in an oven at 120℃ to obtain the NVP precursor. It was then dispersed by hand grinding and calcined in Ar at 700℃ (marked as T1) for 15h. The product was then sieved through a 400-mesh sieve to obtain spherical NVP cathode material.

[0094] (3) Mix 2 mmol of spherical NVP cathode material with 1.5 mmol of sodium carbonate (sodium source), 1.6 mmol of zirconium oxychloride, 0.4 mmol of tetrabutyl titanate (n=0.4), 2 mmol of tetraethyl orthosilicate, 1 mmol of ammonium dihydrogen phosphate, and 3 mmol of formula 1A ( ) and 2mmol formula 2A ( The solvent was dissolved in a mixture of 20 mL ethanol and 40 mL water, and the solvent was dried by stirring at 80 °C. Then, the solvent was thoroughly dried in an oven at 120 °C to obtain the core-shell NZSPT@NVP precursor. Subsequently, it was calcined in Ar at 700 °C (first stage calcination) for 30 h, followed by calcination at 900 °C (second stage calcination) for 8 h to obtain the core-shell NZSPT@NVP inorganic filler.

[0095] (4) Weigh 4 mmol of succinic acid and 4 mmol of sodium fluoride, mix them evenly, and heat them in Ar at 200°C until they are in a molten state. After holding the mixture at this temperature for 30 min, continue to introduce ammonia plasma for 40 s, and then cool it to room temperature. Mix the cooled product with 1 mmol of phosphorus pentoxide evenly, and heat it to 250°C in a vacuum environment for 8 h to obtain SN-F.

[0096] (5) Add 1.6g of NZSPT@NVP inorganic filler to 30mL of acetonitrile solvent, sonicate for 30min to disperse it evenly, then add 2g of PEO and 1.2g of SN-F, stir at room temperature for 6h to dissolve it completely, and cast the resulting transparent slurry into a polytetrafluoroethylene mold with an area of ​​10×10cm. Heat the mold to 60℃ in a vacuum environment and keep it at that temperature to completely evaporate the solvent, thus obtaining PEO / NZSPT@NVP solid electrolyte (also labeled as NZSPT@NVP / PEO).

[0097] The PEO / NZSPT@NVP solid electrolyte prepared in this embodiment, characterized by high sodium conductivity, high chemical stability, and low interfacial resistance, improves the rate performance, cycle life, and energy density of solid sodium-ion batteries. Specific performance analysis is as follows:

[0098] like Figure 1As shown, scanning electron microscopy analysis confirmed that NVP consists of uniformly sized spherical particles with a size of 100-150 nm; the morphology of NZSPT@NVP did not change significantly, but the size increased to about 200 nm, and the surface was covered with a rough and dense coating; the interior of NZSPT@NVP / PEO was filled with a large number of NZSPT@NVP particles, which were evenly distributed and did not show obvious agglomeration.

[0099] like Figure 2 As shown, transmission electron microscopy analysis revealed that NZSPT@NVP has a core-shell structure. The zirconium, titanium, and silicon elements representing NZSPT are distributed in the outer shell, while vanadium is concentrated in the core, further proving the successful coating of NZSP on the NVP surface.

[0100] like Figure 3 As shown, X-ray diffraction analysis revealed that NZSPT@NVP highly corresponds to PDF#97-006-2383 of the C2 / c phase structure. After etching 100 nm, the main peak remained essentially unchanged, indicating high crystal phase purity. This suggests that both the core and shell in the core-shell structure are C2 / c phases.

[0101] like Figure 4 As shown, Fourier transform infrared spectroscopy analysis revealed that the SN-F pair exhibited an absorption peak representing the F ion that split into two distinct absorption peaks. This indicates the coordination environment of the F ion grafted at different positions. Simultaneously, a weak absorption peak appeared around the absorption peak representing the C≡N bond, suggesting that some C≡N bonds were disrupted. Therefore, the F ion in the SN pair is not grafted at a single position, but rather undergoes both substitution and nucleophilic reactions simultaneously. The substitution reaction, which replaces hydrogen ions, is predominant, accompanied by a small amount of nucleophilic reactions that disrupt C≡N bonds.

[0102] like Figure 5 As shown, based on impedance testing, the calculated ionic conductivity of the PEO / NZSPT@NVP solid electrolyte is 5.2 × 10⁻⁶. -4 S / cm, compared to pure PEO solid electrolyte (4.9×10⁻⁶). -9 The increase of more than 5 orders of magnitude in the S / cm indicates that the PEO / NZSPT@NVP solid electrolyte has good sodium conductivity.

[0103] test:

[0104] CR2032 coin cell half-cells were assembled using commercially available NVP electrodes as the positive electrode, sodium electrodes as the negative electrode, and synthesized PEO / NZSPT@NVP as the solid electrolyte. The assembly sequence was as follows: negative electrode shell, spacer, sodium electrode, PEO / NZSPT@NVP solid electrolyte, NVP electrodes, then spacer, spring contacts, and finally the positive electrode shell. The entire battery assembly was completed in an argon-filled glove box. The assembled batteries were then packaged using a coin cell packaging machine, and finally, battery performance testing was performed.

[0105] like Figure 6 As shown, after a 0.5C charge-discharge test, the initial specific capacity of the solid sodium-ion battery using PEO / NZSPT@NVP solid electrolyte reached 151 mAh / g, while that of pure PEO and NZSP / PEO prepared in Comparative Example 4 was only 85 mAh / g and 104 mAh / g, respectively. This proves that the PEO / NZSPT@NVP solid electrolyte can not only improve the specific capacity by enhancing sodium conductivity and reducing voltage polarization, but also further improve the capacity by using the internally coated NVP as an additional active material. According to calculations, the capacity utilization rate of the internally coated NVP can reach 80.3%.

[0106] like Figure 7 As shown, after 2C cycle testing, the specific capacity of the solid sodium-ion battery using PEO / NZSPT@NVP solid electrolyte continued to increase in the first 10 cycles, proving that the capacity of the internally coated NVP was gradually released, and the capacity only decreased by 0.2% after 100 cycles; in contrast, the capacity of PEO decreased by 10.1% after 100 cycles.

[0107] Example 2

[0108] Compared with Example 1, the only difference is that in step (2), the NVP precursor is calcined in Ar at a temperature of 600°C for 12 hours. All other aspects are the same as in Example 1.

[0109] The ionic conductivity of the PEO / NZSPT@NVP solid electrolyte prepared in this embodiment is 4.1 × 10⁻⁶. -4 With an initial specific capacity of 125 mAh / g after a 0.5C charge-discharge test, the capacity decays by 2.5% after 100 cycles at 2C.

[0110] Example 3

[0111] Compared with Example 1, the only difference is that in step (2), the NVP precursor is calcined in Ar at a temperature T1 of 800°C for 18 hours. All other aspects are the same as in Example 1.

[0112] The ionic conductivity of the PEO / NZSPT@NVP solid electrolyte prepared in this embodiment is 3.9 × 10⁻⁶. -4 With an initial specific capacity of 129 mAh / g after a 0.5C charge-discharge test, the capacity decays by 2.0% after 100 cycles at 2C.

[0113] Example 4

[0114] Compared with Example 1, the only difference is that in step (3), zirconium oxychloride is increased to 1.7 mmol and the corresponding tetrabutyl titanate is reduced to 0.3 mmol (that is, n is 0.3), while the rest are the same as in Example 1.

[0115] The ionic conductivity of the PEO / NZSPT@NVP solid electrolyte prepared in this embodiment is 4.0 × 10⁻⁶. -4 With an initial specific capacity of 150mAh / g after a 0.5C charge-discharge test, the capacity decays by 2.8% after 100 cycles at 2C.

[0116] Example 5

[0117] Compared with Example 1, the only difference is that in step (3), zirconium oxychloride is reduced to 1.5 mmol and the corresponding tetrabutyl titanate is increased to 0.5 mmol (that is, n is 0.5), while the rest are the same as in Example 1.

[0118] The ionic conductivity of the PEO / NZSPT@NVP solid electrolyte prepared in this embodiment is 4.3 × 10⁻⁶. -4 With an initial specific capacity of 151 mAh / g after a 0.5C charge-discharge test, the capacity decays by 2.6% after 100 cycles at 2C.

[0119] Example 6

[0120] Compared with Example 1, the only difference is that in step (3), tetrabutyl titanate is replaced with hafnium nitrate, and the rest is the same as in Example 1.

[0121] The ionic conductivity of the PEO / NZSPH@NVP solid electrolyte prepared in this embodiment is 3.9 × 10⁻⁶. -4 With an initial specific capacity of 149 mAh / g after a 0.5C charge-discharge test, the capacity decays by 0.7% after 100 cycles at 2C.

[0122] Example 7

[0123] Compared with Example 1, the only difference is that in step (3), the first stage calcination temperature of the NZSPT@NVP precursor is 600℃ and the calcination time is 24h, and the second stage calcination temperature is 800℃ and the calcination time is 6h. All other aspects are the same as in Example 1.

[0124] The ionic conductivity of the PEO / NZSPT@NVP solid electrolyte prepared in this embodiment is 3.2 × 10⁻⁶. -4 With an initial specific capacity of 146 mAh / g after a 0.5C charge-discharge test, the capacity decays by 3.5% after 100 cycles at 2C.

[0125] Example 8

[0126] Compared with Example 1, the only difference is that in step (3), the first stage calcination temperature of the NZSPT@NVP precursor is 800℃ and the calcination time is 36h, and the second stage calcination temperature is 1000℃ and the calcination time is 10h. All other aspects are the same as in Example 1.

[0127] The ionic conductivity of the PEO / NZSPT@NVP solid electrolyte prepared in this embodiment is 4.9 × 10⁻⁶. -4 With an initial specific capacity of 150mAh / g after a 0.5C charge-discharge test, the capacity decays by 1.2% after 100 cycles at 2C.

[0128] Example 9

[0129] Compared with Example 1, the only difference is that in step (4), sodium fluoride is replaced with sodium bromide, and the rest is the same as in Example 1.

[0130] The ionic conductivity of the PEO / NZSPT@NVP solid electrolyte prepared in this embodiment is 3.8 × 10⁻⁶. -4 With an initial specific capacity of 149 mAh / g after a 0.5C charge-discharge test, the capacity decays by 3.8% after 100 cycles at 2C.

[0131] Example 10

[0132] Compared with Example 1, the only difference is that in step (4), the sodium fluoride is reduced to 2 mmol, and the rest is the same as in Example 1.

[0133] The ionic conductivity of the PEO / NZSPT@NVP solid electrolyte prepared in this embodiment is 4.2 × 10⁻⁶. -4 With an initial specific capacity of 148 mAh / g after a 0.5C charge-discharge test, the capacity decays by 1.2% after 100 cycles at 2C.

[0134] Example 11

[0135] Compared with Example 1, the only difference is that in step (4), the sodium fluoride is increased to 6 mmol, and the rest is the same as in Example 1.

[0136] The ionic conductivity of the PEO / NZSPT@NVP solid electrolyte prepared in this embodiment is 4.4 × 10⁻⁶. -4 With an initial specific capacity of 149 mAh / g after a 0.5C charge-discharge test, the capacity decays by 1.1% after 100 cycles at 2C.

[0137] Example 12

[0138] Compared with Example 1, the only difference is that in step (5), the mass of NZSPT@NVP is reduced from 1.6g to 1.28g, and the rest is the same as in Example 1.

[0139] The ionic conductivity of the PEO / NZSPT@NVP solid electrolyte prepared in this embodiment is 4.4 × 10⁻⁶. -4 With an initial specific capacity of 139 mAh / g after a 0.5C charge-discharge test, the capacity decays by 0.5% after 100 cycles at 2C.

[0140] Example 13

[0141] Compared with Example 1, the only difference is that in step (5), the mass of NZSPT@NVP is increased from 1.6g to 1.92g, and the rest is the same as in Example 1.

[0142] The ionic conductivity of the PEO / NZSPT@NVP solid electrolyte prepared in this embodiment is 4.8 × 10⁻⁶. -4 With an initial specific capacity of 161 mAh / g after a 0.5C charge-discharge test, the capacity did not decrease by 1.0% after 100 cycles at 2C.

[0143] Example 14

[0144] Compared with Example 1, the only difference is that in step (5), the weight ratio of NZSPT@NVP, PEO and SN-F is 1.6:2:1.4, and the rest are the same as in Example 1.

[0145] The ionic conductivity of the PEO / NZSPT@NVP solid electrolyte prepared in this embodiment is 5.1 × 10⁻⁶. -4 With an initial specific capacity of 153 mAh / g after a 0.5C charge-discharge test, the capacity did not decrease by 0.5% after 100 cycles at 2C.

[0146] Example 15

[0147] Compared with Example 1, the only difference is that in step (3), the amount of Formula 1A is reduced to 2 mmol, and the rest is the same as in Example 1.

[0148] The ionic conductivity of the PEO / NZSPT@NVP solid electrolyte prepared in this embodiment is 4.1 × 10⁻⁶. -4 With an initial specific capacity of 147 mAh / g after a 0.5C charge-discharge test, the capacity did not decrease by 1.8% after 100 cycles at 2C.

[0149] Example 16

[0150] Compared with Example 1, the only difference is that in step (3), the amount of Formula 1A is increased to 4 mmol, and the rest is the same as in Example 1.

[0151] The ionic conductivity of the PEO / NZSPT@NVP solid electrolyte prepared in this embodiment is 4.7 × 10⁻⁶. -4 With an initial specific capacity of 148 mAh / g after a 0.5C charge-discharge test, the capacity decayed by only 1.6% after 100 cycles at 2C.

[0152] Example 17

[0153] Compared with Example 1, the only difference is that in step (3), the amount of Formula 2A is reduced to 1 mmol, and the rest is the same as in Example 1.

[0154] The ionic conductivity of the PEO / NZSPT@NVP solid electrolyte prepared in this embodiment is 4.8 × 10⁻⁶. -4 With an initial specific capacity of 149 mAh / g after a 0.5C charge-discharge test, the capacity did not decrease by 1.4% after 100 cycles at 2C.

[0155] Example 18

[0156] Compared with Example 1, the only difference is that in step (3), the amount of Formula 2A is increased to 3 mmol, and the rest is the same as in Example 1.

[0157] The ionic conductivity of the PEO / NZSPT@NVP solid electrolyte prepared in this embodiment is 4.9 × 10⁻⁶. -4 With an initial specific capacity of 150mAh / g after a 0.5C charge-discharge test, the capacity decayed by only 1.4% after 100 cycles at 2C.

[0158] Comparative Example 1

[0159] Compared with Example 1, the only difference is that in step (3), Formula 2A is not added, and the missing Formula 2A is supplemented by an equimolar amount of Formula 1A. The rest is the same as Example 1.

[0160] SEM (see SEM) Figure 8 TEM Figure 9The inner and outer layers of the NZSPT@NVP / PEO solid electrolyte did not form a homogeneous core-shell structure; the ionic conductivity of the prepared NZSPT@NVP / PEO solid electrolyte was 7.4 × 10⁻⁶. -6 The specific capacity is 112 mAh / g after 0.5C discharge and decreases by 5.4% after 100 cycles at 2C.

[0161] Comparative Example 2

[0162] Compared with Example 1, the only difference is that in step (3), Formula 1A is not added, and the missing part is supplemented by an equimolar amount of Formula 2A. The rest is the same as Example 1.

[0163] The morphological results were similar to those of Comparative Example 2, with no homogeneous core-shell structure formed; the ionic conductivity of the prepared NZSP@NVP / PEO solid electrolyte was 1.1 × 10⁻⁶. -5 The specific capacity is 104 mAh / g after 0.5C discharge and decreases by 9.1% after 100 cycles at 2C.

[0164] Comparative Example 3

[0165] Compared with Example 1, the difference is that steps (1) and (2) are omitted, and in step (3), the spherical NVP particles are replaced with NaNi. 0.4 Fe 0.2 Mn 0.4 O2 (NFM) particles; everything else is the same as in Example 1.

[0166] The ionic conductivity of the PEO / NZSPT@NFM solid electrolyte prepared in this embodiment is 7.2 × 10⁻⁶. -8 The specific capacity is 62 mAh / g after 0.5C discharge and decreases by 32.7% after 100 cycles at 2C.

[0167] Comparative Example 4

[0168] Compared with Example 1, the only difference is that (1) and (2) are cancelled, and NVP is not added in step (3); NZSPT is used as an inorganic additive, and the rest are the same as in Example 1.

[0169] The prepared NZSPT / PEO solid electrolyte has a specific capacity of 101 mAh / g after 0.5C discharge and a capacity decay of 6.6% after 100 cycles at 2C.

[0170] Comparative Example 5

[0171] Compared with Example 1, the only difference is that in step (3), n=0, that is, no X source (tetrabutyl titanate) is added, and the missing part is supplemented by Zr; the rest is the same as Example 1.

[0172] like Figure 9 As shown, X-ray diffraction analysis revealed numerous impurity peaks in the NZSP@NVP inorganic filler, indicating low crystal purity. After etching 100 nm, the C2 / c crystal phase of the internal NVP was detected. The ionic conductivity of the prepared NZSP@NVP / PEO solid electrolyte was 4.0 × 10⁻⁶. -7 The specific capacity is 74 mAh / g after 0.5C discharge and decreases by 50.5% after 100 cycles at 2C.

[0173] Comparative Example 6

[0174] Compared with Example 1, the only difference is that sodium fluoride is not added in step (4); the rest is the same as Example 1.

[0175] The prepared NZSP@NVP / PEO solid electrolyte has an ionic conductivity of 1.2 × 10⁻⁶. -6 The specific capacity is 129 mAh / g at 0.5C discharge and decreases by 6.9% after 100 cycles at 2C.

[0176] It should be noted that, in this application, terms such as "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0177] The various embodiments in this specification are described in a related manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0178] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A solid electrolyte modified with dual Na ion channels, characterized in that, It includes a polymer matrix and functional materials dispersed in the polymer matrix; the polymer matrix includes PEO and halogen anion-grafted succinic acid. The functional material is a C2 / c in-phase NZSPX@NVP, which comprises a core of Na3V2(PO4)3 in the C2 / c phase, and Na3Zr in the C2 / c phase coated on the surface of the core. 2-n X n Si2PO 12 The shell; wherein X is at least one of Ti, Hf, Nb, Ta, Mo, Cr, and Sc, and n is 0.1 to 0.

6.

2. The dual Na ion channel modified solid electrolyte as described in claim 1, characterized in that, In the polymer matrix, the halogen anion in the succinate grafted with halogen anions is at least one of fluorine, bromine, chlorine, and iodine. Preferably, the weight ratio of PEO to halogen anion-grafted succinate is 2:0.5~1.5; Preferably, in NZSPX@NVP, the molar ratio of NVP to NZSPX is 1~3:1; the core particle size is 80~120nm; and the shell thickness is 40~60nm. Preferably, in the dual Na ion channel modified solid electrolyte, the weight ratio of PEO to functional material is 2:1~3; more preferably 2:1.2~2; and even more preferably 2:1.5~1.

7.

3. A method for preparing a dual Na ion channel modified solid electrolyte as described in claim 1 or 2, characterized in that the step... include: Step 1: Preparation of functional materials The NVP material with C2 / c phase was obtained. The NVP material, the precursor raw material for synthesizing NZSPX and the co-modifier were mixed in liquid phase and dried. Then, the mixture was calcined to construct the same phase NZSPX on the NVP, thus obtaining the functional material. The combined modifiers include Formula 1 and Formula 2; Formula 1; Formula 2; The R1 mentioned is a carboxyl group, C1~C1. 10 Alkyl or substituted alkyl; A is a carboxylate, sulfonate or sulfate group; substituted alkyl is a group having at least one substituent, either a hydroxyl or a carboxyl group, on an alkyl chain from C1 to C6; R2 is C6~C 20 The alkyl group; R3 is a C1~C3 alkyl group; B - It is a halide anion; Step 2: Preparation of solid electrolyte The solid electrolyte is prepared by mixing functional materials and a polymer matrix.

4. The preparation method of the dual Na ion channel modified solid electrolyte as described in claim 3, characterized in that, The preparation steps of the C2 / c phase NVP material are as follows: vanadium source and ligand are subjected to hydrothermal coordination reaction to obtain V-MOF framework material, then the V-MOF framework material is subjected to the first stage of calcination treatment, and then mixed with phosphorus source and sodium source and subjected to the second stage of calcination treatment to obtain C2 / c phase NVP material. Preferably, the vanadium source is at least one of vanadium oxide and water-soluble salt; Preferably, the ligand comprises at least one of 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, isophthalic acid and its derivatives, 4,4-stilbene dicarboxylic acid or 2-methylimidazole; Preferably, the molar ratio of vanadium to ligand in the vanadium source is 1:0.5~2.5; Preferably, the temperature of the hydrothermal coordination reaction is 100~200℃; Preferably, the hydrothermal coordination reaction takes 12-18 hours; Preferably, the phosphorus source includes at least one cation selected from Na and ammonium, and a compound containing at least one anion selected from phosphate, hydrogen phosphate, and dihydrogen phosphate. Preferably, the sodium source includes at least one of sodium oxides, hydroxides, carbonates, bicarbonates, carboxylates, chlorides, nitrates, and acetates; Preferably, the molar ratio of Na:V:P is 3:2:

3.

5. The preparation method of the dual Na ion channel modified solid electrolyte as described in claim 4, characterized in that, The temperature for the first stage of calcination is 400~500℃; Preferably, the calcination time for the first stage is 3-5 hours; Preferably, the temperature of the second calcination stage is 600~800℃; Preferably, the second calcination time is 12-18 hours.

6. The method for preparing the dual Na ion channel modified solid electrolyte as described in claim 3, characterized in that, In step 1, the precursors for synthesizing NZSPX include sodium source, phosphorus source, zirconium source, silicon source and X source in stoichiometric proportions; Preferably, in Formula 1, A is a carboxylate group, and R1 is a carboxyl group or a C1-C3 substituted alkyl group; the substituents in the substituted alkyl group include at least one of hydroxyl and carboxyl groups; In Equation 2, R2 is C8~C 14 Straight-chain alkyl groups; Preferably, the molar ratio of NZSPX, Formula 1, and Formula 2 is 1:1 to 10:1 to 10; more preferably, it can be 1:1 to 5:1 to 4. Preferably, the solvent for liquid-phase mixing includes at least one of water and C1-C4 alcohols.

7. The method for preparing the dual Na ion channel modified solid electrolyte as described in claim 6, characterized in that, The roasting process consists of two stages: the first stage is roasted at 600-800℃, and the second stage is roasted at 800-1000℃. Preferably, the roasting time for the first stage is 24-36 hours; the roasting time for the second stage is 6-10 hours.

8. The preparation method of the dual Na ion channel modified solid electrolyte as described in claim 3, characterized in that, The preparation steps of halogen anion-grafted succinate are as follows: succinic acid and sodium halide are mixed evenly and heated to a molten state in an inert gas, then ammonia plasma is introduced for a certain time, and then cooled to room temperature; the cooled product is mixed evenly with phosphorus pentoxide, and heated to a certain temperature and held in a vacuum environment for a certain time to obtain halogen anion-grafted succinate. Preferably, in the polymer matrix, the weight ratio of PEO to halogen anion-grafted succinate is 2:0.5~1.5; Preferably, the weight ratio of polymer matrix to functional material is 1~3:1; more preferably 1.5~2.5:

1.

9. The application of the dual Na ion channel modified solid electrolyte according to any one of claims 1-2 or the dual Na ion channel modified solid electrolyte prepared by the preparation method according to any one of claims 3-8, characterized in that, It was used as a solid electrolyte to prepare solid-state sodium-ion batteries.

10. A solid-state sodium-ion battery, characterized in that, The solid electrolyte comprises the dual Na ion channel modified solid electrolyte as described in any one of claims 1 to 2 or the solid electrolyte prepared by the preparation method described in any one of claims 3 to 8.

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