A heterojunction sodium-ion battery halide solid-state electrolyte and a preparation method thereof

Abstract

The application discloses a kind of heterojunction sodium ion battery halide solid electrolyte and preparation method thereof, belong to electrolyte material technical field, first by amino functionalization SBA-15 mesoporous silica and isophorone diisocyanate, 2,2-dichloro-3,3,3-trifluoroprop-1-alcohol is reacted, and modified mesoporous silica of chlorine / flour is prepared, then sodium iodide is loaded on the carrier, and sodium iodide@chlorine fluorine modified mesoporous silica adjuvant is obtained, then the adjuvant is blended with sodium fluoride, tantalum chloride and hafnium chloride, ball milling, and heterojunction sodium ion battery halide solid electrolyte is obtained after cold isostatic pressing;The application solves the problem of high grain boundary impedance and poor structural stability of traditional halide electrolyte by constructing heterojunction interface and optimizing material density, combined with mechanical force induced amorphization and cold isostatic pressing process, can meet the application requirements of high safety, high performance sodium ion battery.

Description

Technical Field

[0001] This invention belongs to the field of electrolyte materials technology, specifically a heterojunction sodium-ion battery halide solid electrolyte and its preparation method. Background Technology

[0002] For a long time, lithium batteries have been constrained by the low and concentrated distribution of lithium resources, resulting in high raw material costs. Meanwhile, liquid electrolytes pose safety risks such as leakage, thermal runaway, and dendrite growth, limiting their large-scale application in energy storage and power applications. Sodium-ion batteries, with their abundant and inexpensive sodium resources, high safety, and lack of dendrite growth risk, have become an ideal alternative to lithium-ion batteries.

[0003] Halide solid electrolytes, as key materials for sodium-ion batteries, possess advantages such as excellent interfacial compatibility, strong chemical stability, and high room-temperature ionic conductivity. They represent a crucial technological approach for constructing safe and high-performance sodium-ion batteries. Through the formation of a stable structure between halide anions and metal cations, they provide an efficient transport channel for sodium ions, forming the core material basis for ensuring battery cycle stability and safety. However, current halide solid electrolytes generally suffer from high crystallinity, poor structural stability, and low ionic conductivity, which restricts their electrochemical performance and commercial application.

[0004] Chinese patent application CN116683018A discloses a method for preparing halide solid electrolytes, halide solid electrolytes and their applications. The method uses a first metal halide containing Ta and Hf and a second metal halide containing Na as raw materials. By adding solvent during ball milling and supplementing with annealing treatment, the problem of high crystallinity and poor structural stability of halide electrolytes is effectively solved. The method achieves the effect of small changes in electrolyte crystal structure, maintaining low crystallinity and high ionic conductivity.

[0005] However, the preparation process still relies on traditional high-energy ball milling, which is prone to decomposition, volatilization, or adverse crystal transformation of the main electrolyte phase due to local high temperature. This results in a decrease in electrolyte sheet density, deterioration of interfacial contact performance, and a significant increase in grain boundary impedance. At the same time, annealing treatment can easily cause secondary damage to the microstructure of the material, making it impossible to balance density and ionic conductivity. This leads to poor interfacial contact and rapid conductivity decay in actual battery applications, making it difficult to meet the core requirements of high-energy-density sodium-ion batteries for long-term stability, low interfacial impedance, and high ionic conductivity. Summary of the Invention

[0006] The purpose of this invention is to provide a heterojunction sodium-ion battery halide solid electrolyte and its preparation method. By constructing a heterojunction interface and optimizing material density, combined with an amorphization modification process, the problems of high grain boundary impedance and poor structural stability of traditional halide electrolytes are solved, which can meet the application requirements of high safety and high performance sodium-ion batteries.

[0007] The objective of this invention can be achieved through the following technical solutions: This invention provides a heterojunction sodium-ion battery halide solid electrolyte, which is obtained by ball milling and cold isostatic pressing of sodium fluoride, tantalum chloride and hafnium chloride as raw materials for halide electrolyte matrix, sodium iodide@chlorofluorine modified mesoporous silica additive.

[0008] This invention also provides a method for preparing a halide solid electrolyte for a heterojunction sodium-ion battery, comprising the following steps: Step 1: Using amino-functionalized mesoporous silica as a matrix, chlorofluorofunctional groups are introduced through a chemical grafting reaction to obtain chlorofluoromodified mesoporous silica, which is then loaded with sodium iodide to obtain sodium iodide@chlorofluoromodified mesoporous silica additive.

[0009] Step 2: Weigh out sodium fluoride, tantalum chloride, and hafnium chloride as raw materials for the halide electrolyte matrix, add sodium iodide@chlorofluorine modified mesoporous silica additive, and ball mill at high energy to obtain electrolyte matrix mixed powder.

[0010] Step 3: The electrolyte matrix mixed powder is cold isostatically pressed under argon protection to obtain a heterojunction sodium-ion battery halide solid electrolyte.

[0011] Furthermore, in the halide solid electrolyte of heterojunction sodium-ion batteries, the molecular formula of the halide electrolyte matrix is: NaTa X Hf 0.5 Cl 5X+2 F, X = 0.25 - 0.6.

[0012] Furthermore, the pressure for cold isostatic pressing is 200-250 MPa, and the holding time is 5 minutes.

[0013] Furthermore, the diameter of the heterojunction sodium-ion battery halide solid electrolyte after cold isostatic pressing is 10 mm and the thickness is 0.48 mm.

[0014] Furthermore, the molar ratio of sodium fluoride, tantalum chloride, and hafnium chloride in the halide electrolyte matrix raw materials is 1:0.25-0.6:0.5; the amount of sodium iodide@chlorofluorine modified mesoporous silica additive added is 0.3-0.5g.

[0015] Furthermore, the specific preparation steps of the sodium iodide@chlorofluoropolymer modified mesoporous silica additive are as follows: Chlorine / fluorine modified mesoporous silica was dispersed in a sodium iodide ethanol solution and ultrasonically dispersed for 30-45 min at 200 W. Then, the ethanol was removed by vacuum rotary evaporation at 40-50 °C, and then vacuum dried at 80 °C for 12 h. After cooling, sodium iodide@chlorofluorine modified mesoporous silica additive was obtained.

[0016] Furthermore, the ratio of chlorine / fluorine modified mesoporous silica to sodium iodide ethanol solution is 4-6 g: 20-30 mL.

[0017] Furthermore, the sodium iodide ethanol solution is prepared by mixing sodium iodide and anhydrous ethanol in a ratio of 0.8-1.5g:20-30mL.

[0018] Furthermore, the specific preparation steps for chlorine / fluorine modified mesoporous silica are as follows: Under nitrogen protection, amino-functionalized SBA-15 mesoporous silica and anhydrous toluene were added to a reactor, followed by isophorone diisocyanate. The reaction was carried out at 105-115℃ and 200-300 r / min for 1.5-2.5 h. Subsequently, 2,2-dichloro-3,3,3-trifluoroprop-1-ol was added, and the reaction was continued for 3.5-4.5 h. After the reaction was completed, the silica was washed by centrifugation with anhydrous toluene, extracted with ethanol by Soxhlet extraction, and dried under vacuum to obtain chlorine / fluorine modified mesoporous silica.

[0019] Furthermore, the ratio of amino-functionalized SBA-15 mesoporous silica, anhydrous toluene, isophorone diisocyanate, and 2,2-dichloro-3,3,3-trifluoroprop-1-ol is 5-7 g: 700-900 mL: 1.2-1.6 mL: 1.6-2 mL.

[0020] The beneficial effects of this invention are: 1. This invention induces the formation of an amorphous / microcrystalline structure in the halide electrolyte matrix through mechanical force. Combined with the heterojunction regulation effect of sodium iodide@chlorofluoromodified mesoporous silica additive, it improves the problems of high grain boundary impedance, low ionic conductivity, and poor interface stability of traditional halide solid electrolytes. It helps to reduce grain boundary impedance, improve room temperature ionic conductivity, and broaden the electrochemical stability window. At the same time, it improves the interfacial compatibility between electrolyte and electrode. It can be used as a solid electrolyte layer for sodium-ion batteries, effectively improving the rate performance and cycle stability of the battery, and meeting the application requirements of high-safety and high-energy-density sodium-ion batteries.

[0021] 2. The sodium iodide@chlorofluorine modified mesoporous silica additive prepared by this invention has multiple advantages: First, as a three-dimensional porous carrier, mesoporous silica provides uniform dispersion sites for sodium iodide, avoiding the aggregation of active components. At the same time, its large specific surface area can provide abundant heterogeneous interfaces and reduce grain boundary resistance. Second, the introduction of chlorofluorine functional groups optimizes the surface polarity of the carrier, improves the interfacial compatibility between the additive and the halide matrix, and can form a stable passivation layer at the interface to suppress side reactions. Third, as an ion source, sodium iodide can form a sodium-rich layer at the interface, reduce the interfacial charge transfer resistance, and further improve ion transport efficiency.

[0022] 3. This invention employs a preparation process combining high-energy ball milling and cold isostatic pressing. On the one hand, the mechanical solid-state reaction can achieve the synthesis and amorphization of the halide matrix in one step, which is simple and easy to scale up, avoiding the problems of component volatilization and grain growth caused by high-temperature sintering. On the other hand, the cold isostatic pressing process can significantly improve the density of the electrolyte, reduce internal pore defects, optimize ion transport channels, and enhance the mechanical strength and dendrite penetration resistance of the electrolyte, thereby improving the safety performance of the battery. Attached Figure Description

[0023] Figure 1 The X-ray diffraction (XRD) pattern is shown for the novel heterojunction sodium-ion battery halide solid electrolyte prepared in Example 1 of this invention.

[0024] Figure 2 The image is a scanning electron microscope (SEM) image of the novel heterojunction sodium-ion battery halide solid electrolyte prepared in Example 1 of this invention.

[0025] Figure 3 The impedance spectrum is shown for the novel heterojunction sodium-ion battery halide solid electrolyte prepared in Example 1 of this invention.

[0026] Figure 4 Impedance spectra of the halide solid electrolytes for novel heterojunction sodium-ion batteries in Examples 1, 2 and 3 of this invention.

[0027] Figure 5 This is a summary graph of the ionic conductivity of the halide solid electrolyte in the novel heterojunction sodium-ion battery of Examples 1, 2 and 3 of the present invention.

[0028] Figure 6 Linear sweep voltammetry curve of the novel heterojunction sodium-ion battery halide solid electrolyte prepared in Example 1 of this invention. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1: A method for preparing a halide solid electrolyte for a heterojunction sodium-ion battery, comprising the following steps: S1: Under nitrogen protection, 6g of amino-functionalized SBA-15 mesoporous silica (activated in vacuum at 200℃ for 4-6h) and 800mL of anhydrous toluene were added to the reactor, followed by 1.4mL of isophorone diisocyanate. The reaction was carried out at 110℃ and 250r / min for 2h. Then, 1.8mL of 2,2-dichloro-3,3,3-trifluoroprop-1-ol was added, and the reaction was continued for 4h. After the reaction was completed, the silica was washed three times by centrifugation with anhydrous toluene, extracted with ethanol by Soxhlet for 12h, and dried in vacuum at 80℃ for 8h to obtain chlorine / fluorine modified mesoporous silica.

[0031] A chemical grafting modification method was adopted, using amino-functionalized SBA-15 mesoporous silica as the matrix. The amino groups on the matrix surface reacted with the isocyanate groups at one end of the isophorone diisocyanate to form urea bonds, forming an intermediate containing a suspended isocyanate group. Then, the suspended isocyanate group reacted with the hydroxyl group of 2,2-dichloro-3,3,3-trifluoroprop-1-ol to form a carbamate bond, thus obtaining modified mesoporous silica with covalently grafted chlorofluoro bifunctional groups on the surface.

[0032] S2: 1.2g of sodium iodide was dispersed in 25mL of anhydrous ethanol to obtain a sodium iodide ethanol solution; 5g of chlorine / fluorine modified mesoporous silica was dispersed in 25mL of sodium iodide ethanol solution and ultrasonically assisted to disperse for 35min at a power of 200W, so that the nano-sized sodium iodide particles partially entered the mesoporous channels. Then, the ethanol was removed by vacuum rotary evaporation at a temperature of 45℃, and then vacuum dried at 80℃ for 12h. After cooling, sodium iodide@chlorine / fluorine modified mesoporous silica additive was obtained.

[0033] S3: 0.839g sodium fluoride (NAF, 1mol), 2.232g tantalum chloride (TaCl5, 0.25mol), 2.021g hafnium chloride (HfCl4, 0.5mol) and 0.3g sodium iodide@chlorofluorine modified mesoporous silica additive were transferred to the ball mill jar of a planetary ball mill. Zirconia grinding balls (5mm in diameter, with a grinding ball to raw material mass ratio of 80:1) were added. The mixture was ball milled at 250r / min for 12h, sieved, and the powder product was taken out to obtain the electrolyte matrix mixed powder.

[0034] Through mechanically induced solid-phase reactions, the raw material particles of sodium fluoride, tantalum chloride, and hafnium chloride halide electrolyte matrix are repeatedly crushed and cold-welded during ball milling to form a highly uniform composite at the microscale. At the same time, mechanical energy generates a large number of defects in the crystal lattice, activating the reactivity of the raw materials. The sodium iodide@chlorofluorine modified mesoporous silica additive is uniformly dispersed and forms a heterojunction with the formed halide electrolyte matrix to construct a heterojunction structure.

[0035] S4: Place the electrolyte matrix mixed powder in an argon-protected glove box, load it into a cold isostatic pressing mold, and use the cold isostatic pressing process to press it into a dense blank sheet with a diameter of 10 mm and a thickness of 0.48 mm under a pressure of 200 MPa for 5 minutes, thus obtaining the heterojunction sodium-ion battery halide solid electrolyte.

[0036] Example 2: This example provides a novel heterojunction sodium-ion battery halide solid electrolyte. The difference from Example 1 is that the molar ratio of sodium fluoride, tantalum chloride and hafnium chloride in step S3 is 1:0.5:0.5. The remaining steps and parameters are kept the same, and a novel heterojunction sodium-ion battery halide solid electrolyte is prepared.

[0037] Example 3: This example provides a novel heterojunction sodium-ion battery halide solid electrolyte. The difference from Example 1 is that in step S3, the molar ratio of sodium fluoride, tantalum chloride, and hafnium chloride is 1:0.6:0.5, and in step S4, the cold isostatic pressure is adjusted to 250 MPa. Steps S1 and S2 remain unchanged, and the parameters are kept consistent. The specific steps S3 and S4 are as follows: S3: 0.839g sodium fluoride (1mol), 5.357g tantalum chloride (0.6mol), 2.021g hafnium chloride (0.5mol) and 0.3g sodium iodide@chlorofluorine modified mesoporous silica additive were transferred to the ball mill jar of a planetary ball mill. Zirconia grinding balls (5mm in diameter, with a mass ratio of grinding balls to raw materials of 80:1) were added. The mixture was ball milled at 250r / min for 12h, sieved, and the powder product was taken out to obtain electrolyte matrix mixed powder.

[0038] S4: The electrolyte matrix mixed powder is placed in an argon glove box, then placed into a cold isostatic pressing mold and pressed under a pressure of 250MPa for 5 minutes to form a dense blank sheet with a diameter of 10mm and a thickness of 0.48mm, thus obtaining a heterojunction sodium-ion battery halide solid electrolyte.

[0039] Examples 4-5: These examples provide a method for preparing a halide solid electrolyte for a heterojunction sodium-ion battery. The difference from Example 1 is that the amount of substance added in step S1 is different, while the remaining steps and parameters remain the same. The specific amounts added are shown in Table 1 below: Table 1. Comparison of the amount of substances used in step S1

[0040] Examples 6-7: This example provides a method for preparing a halide solid electrolyte for a heterojunction sodium-ion battery. The difference from Example 1 is that the amount of substance added in step S2 is different, while the other steps and parameters remain the same. The specific amounts added are shown in Table 2 below: Table 2 Comparison of Substance Amounts in Step S2

[0041] Example 8: This example provides a method for preparing a halide solid electrolyte for a heterojunction sodium-ion battery. The difference from Example 1 is that the amount of sodium iodide@chlorofluoromodified mesoporous silica additive added in step S3 is 0.5g, while the remaining steps and parameters remain the same.

[0042] Comparative Example 1: Based on Example 1, the sodium iodide@chlorofluorine modified mesoporous silica additive prepared in steps S1 and S2 was omitted. In step S3, sodium fluoride, tantalum chloride and hafnium chloride were used as raw materials and directly ball-milled in a molar ratio of 1:0.25:0.5. The remaining steps and parameters remained unchanged to obtain a halide solid electrolyte.

[0043] Comparative Example 2: Based on Example 1, the chlorine / fluorine modified mesoporous silica support prepared in step S1 was omitted. In step S3, sodium fluoride, tantalum chloride, hafnium chloride and sodium iodide were directly mixed and ball-milled in the original ratio. The remaining steps and parameters remained unchanged to obtain a halide solid electrolyte.

[0044] Comparative Example 3: Based on Example 1, the sodium iodide loading process in step S2 was omitted. In step S3, sodium fluoride, tantalum chloride, hafnium chloride and chlorine / fluorine modified mesoporous silica were directly mixed and ball-milled in the original ratio. The remaining steps and parameters remained unchanged to obtain a halide solid electrolyte.

[0045] Comparative Example 4: Based on Example 1, the cold isostatic pressure in step S4 was adjusted to 150 MPa, while the other steps and parameters remained unchanged, to obtain a halide solid electrolyte.

[0046] The halide solid electrolytes prepared in Examples 1-8 and Comparative Examples 1-5 were subjected to the following performance tests: X-ray diffraction (XRD) test: The crystal structure of the electrolyte powder sample was characterized by X-ray diffraction. The test conditions were Cu target Kα rays, scanning range of 10°-80°, and scanning speed of 2° / min. The phase composition and crystallization state of the electrolyte were analyzed by XRD pattern. If there are no obvious sharp diffraction peaks in the XRD pattern, but only broadened diffuse bulges, it indicates that the electrolyte is mainly amorphous. This disordered structure is beneficial to reduce grain boundary impedance and improve ion transport capability.

[0047] according to Figure 1 (X-ray diffraction pattern of the novel heterojunction sodium-ion battery halide solid electrolyte prepared in Example 1) It can be seen that the sample did not show obvious sharp characteristic diffraction peaks in the test range of 2θ=10°-80°, but only broadened diffuse bulges, indicating that the electrolyte sample is mainly amorphous and the content of long-range ordered crystalline phase is extremely low. This disordered amorphous structure can effectively reduce grain boundary impedance, provide a continuous and low-barrier transport channel for sodium ions, which is conducive to improving the overall ionic conductivity of the electrolyte and provides a structural basis for the subsequent excellent electrochemical performance.

[0048] Scanning electron microscopy (SEM) test: Field emission scanning electron microscopy (SEM) was used to observe the microstructure of the electrolyte powder. Before the test, the sample was sputtered with gold to improve conductivity. The size, morphology and dispersion of the powder particles were analyzed by SEM images. The electrolyte powder with fine and uniform particles is more likely to form a dense solid electrolyte sheet after cold isostatic pressing, which reduces pore defects and thus reduces interfacial impedance.

[0049] according to Figure 2 (Scanning electron microscope image of the novel heterojunction sodium-ion battery halide solid electrolyte prepared in Example 1) It can be seen that the electrolyte powder particles have a fine, uniform, and irregular morphology, with no obvious agglomeration between particles, a narrow size distribution, and good dispersibility. This uniform micromorphology is conducive to the formation of dense, low-porosity electrolyte sheets during cold isostatic pressing, reducing interface defects and grain boundary voids, lowering interface impedance, and providing a stable transport path for long-range migration of sodium ions.

[0050] Ionic conductivity test: Weigh 200 mg of the halide solid electrolyte to be tested and place it in a solid-state battery pressure test mold. Spread aluminum-coated carbon on both sides of the solid electrolyte and press it with 200 MPa. Perform AC impedance testing on a Biologic electrochemical workstation. Calculate the ionic conductivity based on the obtained AC impedance spectrum and the formula: σ = L / R; where σ is the ionic conductivity (S / cm), L is the thickness of the electrolyte membrane (cm), R is the measured impedance (Ω), and S is the area of ​​the electrolyte membrane (cm²). 2 ).

[0051] Electrochemical window test: Weigh 100 mg of the halide solid electrolyte to be tested, press it into a tablet using a 10 mm tableting mold at 200 MPa, open one side of the mold, and add Na3PS4 electrolyte and Na2S4 electrolyte sequentially. 15 The Sn4 sodium-tin alloy was then pressed at 300 MPa. After pressing, a mixture of the solid electrolyte and conductive carbon black (mass ratio 9:1) was added to the other side of the mold. Finally, it was pressed at 350 MPa to complete the assembly. The electrochemical window of the solid electrolyte was tested using linear sweep voltammetry.

[0052] The results are shown in Table 3: Table 3 Performance test results of various halide solid electrolytes

[0053] Based on the above test results combined with the relevant impedance spectrum ( Figure 3 and Figure 4 Comparison of electrical conductivity () Figure 5 ) and linear sweep voltammetry curve ( Figure 6 As can be seen, the heterojunction sodium-ion battery halide solid electrolyte prepared in the embodiments of the present invention achieves the dual effects of reducing grain boundary impedance and optimizing interface stability through the synergistic modification of sodium iodide@chlorofluorine modified mesoporous silica additive, effectively improving the ion transport capacity and electrochemical window stability of the electrolyte. As the molar ratio of each component, the amount of additives added, and the cold isostatic pressure are adjusted within a reasonable range in the present invention, the ionic conductivity and electrochemical window of the electrolyte are maintained at a relatively excellent level, indicating that the preparation process of the present invention has good stability and adaptability, and small fluctuations in process conditions will not have a significant adverse effect on the core performance.

[0054] In Comparative Example 1, no sodium iodide@chlorofluoromodified mesoporous silica additive was added. Electrolytes were directly prepared using sodium fluoride, tantalum chloride, and hafnium chloride as raw materials. The ionic conductivity of the resulting electrolyte was significantly lower than that of the example, and the electrochemical window was significantly narrowed. This result indicates that the introduction of additives is a key factor in improving the overall performance of electrolytes. It is difficult to overcome the performance degradation caused by grain boundary impedance and interface defects by relying solely on the matrix electrolyte itself.

[0055] In Comparative Example 2, sodium iodide was directly blended with the matrix electrolyte without the introduction of chlorine / fluorine modified mesoporous silica support. Although the ionic conductivity and electrochemical window of the resulting electrolyte were improved, the improvement was limited and still lower than those of the examples. This result indicates that the function of adding sodium iodide alone is limited. Constructing heterogeneous interfaces and reducing grain boundary impedance require the synergistic cooperation of the support. It is difficult to achieve the ideal ion transport optimization effect by relying solely on sodium iodide.

[0056] In Comparative Example 3, only chlorine / fluorine modified mesoporous silica support was blended with the matrix electrolyte without introducing sodium iodide loading process. The resulting electrolyte had higher ionic conductivity and electrochemical window than Comparative Example 1 and Comparative Example 2, but still lower than the example. This result shows that the synergistic effect of sodium iodide is indispensable, proving that the simultaneous introduction of interfacial ion source and optimization of support framework is the key to obtaining low impedance and high stability electrolyte.

[0057] In Comparative Example 4, the electrolyte was prepared using a lower cold isostatic pressing pressure. The resulting electrolyte exhibited better ionic conductivity and electrochemical window than some samples in Comparative Examples 1 to 3, but still lower than the examples. This result indicates that the cold isostatic pressing pressure set in this invention is crucial for achieving electrolyte densification. Electrolyte sheets prepared under lower pressure have higher porosity and increased interfacial impedance, making it impossible to form a dense ion transport network like that in the examples of this invention. Consequently, it is difficult to effectively reduce grain boundary impedance and improve overall ionic conductivity.

[0058] It should be noted that, in this document, 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 process, method, article, or apparatus.

[0059] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for preparing a halide solid electrolyte for a heterojunction sodium-ion battery, characterized in that, Includes the following steps: Step 1: Using amino-functionalized mesoporous silica as a matrix, chlorofluoro functional groups are introduced through a chemical grafting reaction to obtain chlorofluoro-modified mesoporous silica, which is then loaded with sodium iodide to obtain sodium iodide@chlorofluoro-modified mesoporous silica additive. Step 2: Weigh sodium fluoride, tantalum chloride, and hafnium chloride, which are used as raw materials for the halide electrolyte matrix, add sodium iodide@chlorofluorine modified mesoporous silica additive, and ball mill to obtain electrolyte matrix mixed powder; Step 3: The electrolyte matrix mixed powder is cold isostatically pressed under argon protection to obtain a heterojunction sodium-ion battery halide solid electrolyte; In the heterojunction sodium-ion battery halide solid electrolyte, the molecular formula of the halide electrolyte matrix is: NaTa x Hf 0.5 Cl 5X+2 F, X = 0.25 - 0.

6.

2. The method for preparing a halide solid electrolyte for a heterojunction sodium-ion battery according to claim 1, characterized in that, The pressure for cold isostatic pressing is 200-250 MPa, and the holding time is 5 minutes.

3. The method for preparing a halide solid electrolyte for a heterojunction sodium-ion battery according to claim 1, characterized in that, The heterojunction sodium-ion battery halide solid electrolyte formed by cold isostatic pressing has a diameter of 10 mm and a thickness of 0.48 mm.

4. The method for preparing a halide solid electrolyte for a heterojunction sodium-ion battery according to claim 1, characterized in that, The molar ratio of sodium fluoride, tantalum chloride, and hafnium chloride in the halide electrolyte matrix raw materials is 1:0.25-0.6:0.5; the amount of sodium iodide@chlorofluorine modified mesoporous silica additive added is 0.3-0.5g.

5. The method for preparing a halide solid electrolyte for a heterojunction sodium-ion battery according to claim 1, characterized in that, The specific preparation steps of the sodium iodide@chlorofluorine modified mesoporous silica additive are as follows: Chlorine / fluorine modified mesoporous silica was dispersed in a sodium iodide ethanol solution and ultrasonically dispersed for 30-45 min at 200 W. Then, the ethanol was removed by vacuum rotary evaporation at 40-50 °C, and then vacuum dried at 80 °C for 12 h. After cooling, sodium iodide@chlorofluorine modified mesoporous silica additive was obtained.

6. The method for preparing a halide solid electrolyte for a heterojunction sodium-ion battery according to claim 5, characterized in that, The ratio of the chlorine / fluorine modified mesoporous silica to sodium iodide ethanol solution is 4-6g: 20-30mL.

7. The method for preparing a halide solid electrolyte for a heterojunction sodium-ion battery according to claim 5, characterized in that, The sodium iodide ethanol solution is prepared by mixing sodium iodide and anhydrous ethanol in a ratio of 0.8-1.5g:20-30mL.

8. The method for preparing a halide solid electrolyte for a heterojunction sodium-ion battery according to claim 5, characterized in that, The specific preparation steps for the chlorine / fluorine modified mesoporous silica are as follows: Under nitrogen protection, amino-functionalized SBA-15 mesoporous silica and anhydrous toluene were added to a reactor, followed by isophorone diisocyanate. The reaction was carried out at 105-115℃ and 200-300 r / min for 1.5-2.5 h. Subsequently, 2,2-dichloro-3,3,3-trifluoroprop-1-ol was added, and the reaction was continued for 3.5-4.5 h. After the reaction was completed, the silica was washed by centrifugation with anhydrous toluene, extracted with ethanol by Soxhlet extraction, and dried under vacuum to obtain chlorine / fluorine modified mesoporous silica.

9. The method for preparing a halide solid electrolyte for a heterojunction sodium-ion battery according to claim 8, characterized in that, The ratio of amino-functionalized SBA-15 mesoporous silica, anhydrous toluene, isophorone diisocyanate, and 2,2-dichloro-3,3,3-trifluoroprop-1-ol is 5-7 g: 700-900 mL: 1.2-1.6 mL: 1.6-2 mL.

10. A halide solid electrolyte for heterojunction sodium-ion batteries, characterized in that, It is prepared by the preparation method described in any one of claims 1-9.

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