A high temperature sodium ion battery and vehicle thereof

Abstract

The present invention discloses a high-temperature sodium ion battery and a vehicle thereof, and relates to the technical field of sodium ion batteries. The sodium ion battery comprises a high-stability positive electrode material, a high-stability negative electrode material, a high-temperature resistant electrolyte and a battery separator; wherein the high-temperature resistant electrolyte comprises a NaBOB derivative used as an electrolyte sodium salt; the preparation method of the above-mentioned NaBOB derivative comprises: taking boric acid and sodium hydroxide and doping an organic acid by a solid phase sintering method to obtain a NaBOB derivative; wherein the organic acid comprises 4-(2-carboxyethyl)-4-nitropimelic acid. The sodium ion battery provided by the present invention has excellent electrochemical properties, its room temperature cycle performance is significantly improved, and its high temperature resistance performance is also significantly improved, and the capacity retention rate is significantly increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of sodium ion battery materials, and in particular relates to a high-temperature sodium ion battery and a vehicle thereof. Background Art

[0002] Sodium-ion batteries have attracted extensive attention in recent years due to their advantages such as abundant raw materials, excellent low-temperature performance, and high safety. Hard carbon is currently considered one of the most promising negative electrode materials for sodium-ion batteries. However, due to the rich pore structure on the surface of hard carbon, the surface activity is strong, and the electrolyte interface film on the negative electrode surface is less stable, resulting in safety risks such as gas production and sodium precipitation in sodium-ion batteries under high temperature environments; and use defects such as reduced cycle stability. Existing technologies have difficulty in making major breakthroughs in improving the high-temperature performance of sodium-ion batteries. At present, the following solutions are generally adopted to address the high-temperature problem of batteries: (1) reducing the amount of electrolyte. Excessive electrolyte will cause the dissolution of unstable interface films during the cycle; (2) increasing the sodium salt concentration. A higher sodium salt concentration can reduce the dissolution of the interface film; (3) using high-temperature additives. Additives can improve the stability of the interface film at high temperatures. However, the above-mentioned modification methods have certain defects. For example, reducing the amount of electrolyte can easily lead to an increase in the internal resistance of the battery and a decrease in the cycle life; increasing the sodium salt concentration will increase the viscosity of the electrolyte, poor wettability, and increase costs; and it is difficult to develop high-temperature additives. Summary of the invention

[0003] The object of the present invention is to provide a high-temperature sodium ion battery and a vehicle thereof, wherein the sodium ion battery has excellent electrochemical properties, its room temperature cycle performance is significantly improved, its high temperature resistance performance is also significantly improved, and its capacity retention rate is significantly increased.

[0004] The technical solution adopted by the present invention to achieve the above-mentioned purpose is:

[0005] A method for preparing a NaBOB derivative used as an electrolyte sodium salt comprises: taking boric acid and sodium hydroxide and doping an organic acid through a solid phase sintering method to obtain a NaBOB derivative;

[0006] Among them, the organic acid includes 4-(2-carboxyethyl)-4-nitroheptanedioic acid. The present invention adopts 4-(2-carboxyethyl)-4-nitroheptanedioic acid to dope modified NaBOB to obtain NaBOB derivatives, which have more excellent conductive properties and significantly improved conductivity; as a sodium salt, it is used in an electrolyte to prepare a sodium ion battery, which can effectively improve the electrochemical properties of the battery, enhance its cycle stability, and significantly improve its high temperature resistance. The reason may be that after doping with 4-(2-carboxyethyl)-4-nitroheptanedioic acid, the sodium salt structure can be more effectively improved, which may enhance its solubility and stability, further optimize the electrolyte structure, and then effectively improve the battery's room temperature and high temperature performance.

[0007] More specifically, the preparation method of the above NaBOB derivative comprises:

[0008] Take 4-(2-carboxyethyl)-4-nitroheptanedioic acid, boric acid and sodium hydroxide, mix them, grind them by manual dry grinding, then put them in a crucible, transfer them to an oven and keep them at 110-120°C for 5-7 hours, then continue to heat to 240-250°C and keep them at 5-7 hours, then cool them to room temperature, wash them with anhydrous ethanol, and vacuum dry them at 50-60°C for 4-6 hours to obtain a NaBOB derivative.

[0009] Specifically, the molar ratio of 4-(2-carboxyethyl)-4-nitroheptanedioic acid, boric acid and sodium hydroxide is 1.8-2.2:1:1.

[0010] A high temperature resistant electrolyte comprises a NaBOB derivative used as electrolyte sodium salt prepared by the above method.

[0011] Specifically, the high temperature electrolyte includes an organic mixed solvent and a high temperature additive.

[0012] Specifically, the concentration of electrolyte sodium salt in the high temperature resistant electrolyte is 0.8-1.2 mol / L; the concentration of high temperature additive is 1.5-3 wt%.

[0013] Specifically, the electrolyte sodium salt can also be selected from at least one of NaBOB, NaBF4, NaSbF6, NaPF6, NaPOF4 and NaCF3CO2.

[0014] Specifically, the organic mixed solvent includes a carbonate solvent and an ether solvent, and the mass ratio of the two is 1.5~2.5:1; wherein the carbonate solvent includes at least two of ethylene carbonate, dimethyl carbonate, diethyl carbonate and fluoroethylene carbonate; the ether solvent includes at least one of tetrahydrofuran, diethylene glycol dimethyl ether, diethylene glycol dimethyl ether and ethyl nonafluorobutyl ether.

[0015] Specifically preferably, the high-temperature additive includes 4-((trimethylsilyl)ethynyl)morpholine. The present invention simultaneously adds the high-temperature additive 4-((trimethylsilyl)ethynyl)morpholine to the electrolyte, which can further improve the room-temperature and high-temperature electrochemical performance of the battery; and in the presence of NaBOB derivatives, the two can have a synergistic enhancement effect, significantly improving the room-temperature and high-temperature performance of the sodium-ion battery, and the capacity retention rate is significantly improved. The reason may be that it can better form stable SEI and CEI films on the surface of the positive and negative electrode materials, prevent the dissolution of the positive electrode material metal and the destruction of the surface film of the negative electrode material under high temperature conditions, and improve the high-temperature stability of the sodium-ion battery.

[0016] A high-temperature sodium ion battery comprises the above-mentioned high-temperature resistant electrolyte.

[0017] Specifically, the battery also includes a high-stability positive electrode material, a high-stability negative electrode material, a high-temperature resistant electrolyte and a battery separator.

[0018] Specifically, the battery separator includes polyimide aerogel.

[0019] Furthermore, the preparation method of the above-mentioned battery separator comprises:

[0020] Take 4,4'-diaminodiphenyl ether and add NMP to dissolve, add 3,3,4,4-biphenyltetracarboxylic dianhydride, add crosslinking agent BTMSPA after the solution becomes transparent, stir vigorously for 20-40 minutes, add dehydrating agent acetic anhydride and catalyst pyridine, remove bubbles by ultrasound, and obtain a polymer solution; then coat it on an automatic coating machine, and obtain a polymer wet gel film after 8-12 minutes. After placing it for 0.5-1.5 days, immerse it in a mixed solvent of NMP and acetone, immerse it for 24-30 hours, and change the solvent every 12 hours; then immerse it in an acetone solution, immerse it for 24-30 hours, and change the solvent every 12 hours; then place it in a supercritical drying device, and use a wire plate to flatten and fix the film, adjust the carbon dioxide to a supercritical state, and dry it at 50-60°C and 10-12MPa for 2-3 days, and take it out to obtain a battery separator.

[0021] Specifically, the solid-liquid ratio of 4,4'-diaminodiphenyl ether to NMP is 0.04~0.06g:1mL; the molar ratio of 3,3,4,4-biphenyltetracarboxylic dianhydride to 4,4'-diaminodiphenyl ether is 1.1~1.5:1; the molar ratio of the crosslinking agent BTMSPA to 4,4'-diaminodiphenyl ether is 0.07~0.08:1; the usage ratio of the dehydrating agent acetic anhydride to 4,4'-diaminodiphenyl ether is 0.6~0.8mL:1mmol; the usage ratio of the catalyst pyridine to 4,4'-diaminodiphenyl ether is 0.6~0.7mL:1mmol.

[0022] More preferably, 4,4'-dihydrazinostilbene-2,2'-disulfonic acid is used instead of 4,4'-diaminodiphenyl ether in the preparation process of the battery separator. The present invention uses 4,4'-dihydrazinostilbene-2,2'-disulfonic acid as a functional monomer and is compounded and polymerized with other components to prepare a battery separator, which can effectively improve the pore structure of the battery separator, significantly increase the porosity, and enhance the liquid absorption capacity, and further improve the liquid absorption rate; at the same time, the prepared battery separator exhibits higher high temperature resistance. When applied to the preparation process of sodium ion batteries, it can effectively enhance the high temperature use capability of the battery, and also has a beneficial effect on the normal temperature cycle stability of the battery, and its capacity retention rate of 2000 cycles is significantly improved.

[0023] The invention further discloses the use of the NaBOB derivative obtained by the preparation method in preparing electrolyte or battery.

[0024] The present invention also discloses the use of the above-mentioned high temperature resistant electrolyte in preparing a battery for energy storage.

[0025] A vehicle comprises the battery.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention adopts 4-(2-carboxyethyl)-4-nitroheptanedioic acid to dope modified NaBOB to obtain NaBOB derivatives, which have more excellent conductive properties and significantly improve their conductivity; as a sodium salt, it is used in an electrolyte to prepare a sodium ion battery, which can effectively improve the electrochemical performance of the battery, enhance its cycle stability, and significantly improve its high temperature performance. At the same time, adding a high temperature additive 4-((trimethylsilyl)ethynyl)morpholine to the electrolyte can further improve the room temperature and high temperature electrochemical performance of the battery; and in the presence of the NaBOB derivative, the two can play a synergistic enhancement effect. The present invention adopts 4,4'-dihydrazinodiphenylethylene-2,2'-disulfonic acid as a functional monomer and is polymerized with other components to prepare a battery separator, which can effectively improve the pore structure of the battery separator, and the liquid absorption performance is further improved; at the same time, the prepared battery separator exhibits a higher high temperature resistance. Applying it in the preparation process of sodium ion batteries can effectively enhance the room temperature and high temperature performance of the battery; further broaden the scope of application of sodium ion batteries and improve the practicality of sodium ion batteries.

[0028] Therefore, the present invention provides a high-temperature sodium ion battery and a vehicle thereof, wherein the sodium ion battery has excellent electrochemical properties, its room temperature cycle performance is significantly improved, its high temperature resistance performance is also significantly improved, and its capacity retention rate is significantly increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The infrared test results of the NaBOB derivatives and NaBOB prepared in Example 1 of the present invention are shown;

[0030] Figure 2 The infrared test results of the battery separator prepared in the embodiment of the present invention are as follows;

[0031] Figure 3 TG curve test results of the battery separator prepared in the embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, each embodiment of the present invention will be described in detail below in conjunction with the embodiments. However, it will be appreciated by those skilled in the art that in each embodiment of the present invention, many technical details are proposed in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present application can be implemented.

[0033] Embodiment 1:

[0034] A high-temperature sodium-ion battery comprises a high-stability positive electrode material, a high-stability negative electrode material, a high-temperature resistant electrolyte and a battery separator.

[0035] A high temperature resistant electrolyte comprises: an electrolyte sodium salt, an organic mixed solvent, and a high temperature additive; wherein the electrolyte sodium salt is a NaBOB derivative with a concentration of 1.1 mol / L; the concentration of the high temperature additive is 2.2 wt%; the organic mixed solvent comprises a carbonate solvent (ethylene carbonate) and an ether solvent (tetrahydrofuran) with a mass ratio of 2.2:1; and the high temperature additive is 4-((trimethylsilyl)ethynyl)morpholine.

[0036] Preparation of NaBOB derivatives:

[0037] 4-(2-carboxyethyl)-4-nitroheptanedioic acid, boric acid and sodium hydroxide (molar ratio of 2.1:1:1) were mixed, ground by manual dry grinding, placed in a crucible, transferred to an oven and kept at 110°C for 6 hours, then continued to heat to 240°C and kept for 6 hours, then cooled to room temperature, washed with anhydrous ethanol for multiple times, and vacuum dried at 60°C for 4 hours to obtain a NaBOB derivative.

[0038] Preparation of battery separator:

[0039] Take 4,4'-diaminodiphenyl ether and add NMP (solid-liquid ratio of 0.05g:1mL) to dissolve, add 3,3,4,4-biphenyltetracarboxylic dianhydride (molar ratio with 4,4'-diaminodiphenyl ether is 1.3:1), add crosslinking agent BTMSPA (molar ratio with 4,4'-diaminodiphenyl ether is 0.075:1) after the solution becomes transparent, stir vigorously for 30min, add dehydrating agent acetic anhydride (molar ratio with 4,4'-diaminodiphenyl ether is 0.7mL:1mmol), catalyst pyridine (molar ratio with 4,4'-diaminodiphenyl ether is 0.001mmol), add 4,4'-diaminodiphenyl ether ...3'-diaminodiphenyl ether (molar ratio with 4,4'-diaminodiphenyl ether is 0 The molecular weight ratio is 0.66mL:1mmol), and bubbles are removed by ultrasound to obtain a polymer solution; then, the film is coated on an automatic coating machine, and a polymer wet gel film is obtained after 10 minutes. After being placed for 1 day, it is immersed in a mixed solvent of NMP and acetone for 24 hours, and the solvent is changed every 12 hours; then it is immersed in an acetone solution for 24 hours, and the solvent is changed every 12 hours; then it is placed in a supercritical drying device, and the film is flattened and fixed with a wire plate, etc., the carbon dioxide is adjusted to a supercritical state, and dried at 56°C and 11.5MPa for 3 days, and the battery separator is obtained.

[0040] Preparation of a high-temperature sodium-ion battery:

[0041] The positive electrode active materials sodium vanadium fluorophosphate, polyvinylidene fluoride, and acetylene black were mixed uniformly in a mass ratio of 85:7:8 and coated on aluminum foil to make a positive electrode sheet. The active material loading of the positive electrode was 20 mg cm -2 The negative electrode active materials hard carbon, carboxymethyl cellulose and acetylene black were mixed evenly in a mass ratio of 90:5:5 and coated on copper foil to make a negative electrode sheet. The loading of the negative electrode active material was 36 mg cm -2 ; Metallic sodium is the counter electrode and the battery separator prepared above, and the electrolyte prepared above is used to prepare a CR2032 button sodium ion battery in an argon glove box.

[0042] Embodiment 2:

[0043] A high-temperature sodium ion battery differs from Example 1 in that the high-temperature resistant electrolyte is prepared in this example.

[0044] The concentration of the electrolyte sodium salt NaBOB derivative in a high temperature resistant electrolyte is 0.85 mol / L; the concentration of the high temperature additive 4-((trimethylsilyl)ethynyl)morpholine is 1.7wt%. The organic mixed solvent includes a carbonate solvent and an ether solvent, and the mass ratio of the two is 1.6:1; wherein the carbonate solvent is dimethyl carbonate; and the ether solvent is glycol dimethyl ether.

[0045] The preparation of the NaBOB derivative is different from that of Example 1 in that the molar ratio of 4-(2-carboxyethyl)-4-nitroheptanedioic acid, boric acid and sodium hydroxide is 1.9:1:1.

[0046] The preparation of the battery separator is the same as that in Example 1.

[0047] The preparation of a high temperature sodium ion battery is the same as that in Example 1.

[0048] Embodiment 3:

[0049] A high-temperature sodium ion battery differs from Example 1 in that the high-temperature resistant electrolyte is prepared in this example.

[0050] The concentration of the electrolyte sodium salt NaBOB derivative in a high temperature resistant electrolyte is 1.2 mol / L; the concentration of the high temperature additive 4-((trimethylsilyl)ethynyl)morpholine is 1.5wt%. The organic mixed solvent includes a carbonate solvent and an ether solvent, and the mass ratio of the two is 2:1; wherein the carbonate solvent is diethyl carbonate; and the ether solvent is diethylene glycol dimethyl ether.

[0051] The preparation of the NaBOB derivative is different from that of Example 1 in that the molar ratio of 4-(2-carboxyethyl)-4-nitroheptanedioic acid, boric acid and sodium hydroxide is 1.8:1:1.

[0052] The preparation of the battery separator is the same as that in Example 1.

[0053] The preparation of a high temperature sodium ion battery is the same as that in Example 1.

[0054] Embodiment 4:

[0055] A high-temperature sodium ion battery differs from Example 1 in that the high-temperature resistant electrolyte is prepared in this example.

[0056] A high temperature resistant electrolyte differs from Example 1 in that the electrolyte sodium salt includes NaPF6.

[0057] The preparation of the battery separator is the same as that in Example 1.

[0058] The preparation of a high temperature sodium ion battery is the same as that in Example 1.

[0059] Embodiment 5:

[0060] A high-temperature sodium ion battery differs from Example 1 in that the high-temperature resistant electrolyte is prepared in this example.

[0061] The difference between a high temperature resistant electrolyte and Example 1 is that the high temperature additive is an equimolar amount of 3-trimethylsilyl-2-oxazolidinone.

[0062] The preparation of the battery separator is the same as that in Example 1.

[0063] The preparation of a high temperature sodium ion battery is the same as that in Example 1.

[0064] Embodiment 6:

[0065] A high-temperature sodium ion battery differs from Example 4 in that the high-temperature resistant electrolyte is prepared in this example.

[0066] A high temperature resistant electrolyte differs from Example 4 in that the high temperature additive is an equimolar amount of 3-trimethylsilyl-2-oxazolidinone.

[0067] The preparation of the battery separator is the same as that in Example 1.

[0068] The preparation of a high temperature sodium ion battery is the same as that in Example 1.

[0069] Embodiment 7:

[0070] A high-temperature sodium ion battery differs from Example 1 in that the battery separator is prepared in this example.

[0071] The difference between the preparation of the battery separator and Example 1 is that:

[0072] An equal molar amount of 4,4'-dihydrazinostilbene-2,2'-disulfonic acid was used to replace 4,4'-diaminodiphenyl ether.

[0073] The preparation of a high temperature sodium ion battery is the same as that in Example 1.

[0074] Embodiment 8:

[0075] A high-temperature sodium ion battery differs from Example 6 in that the battery separator is prepared in this example.

[0076] The preparation of the battery separator is the same as that of Example 7.

[0077] The preparation of a high temperature sodium ion battery is the same as that in Example 1.

[0078] Comparative Example 1:

[0079] A high-temperature sodium ion battery differs from Example 5 in that the high-temperature resistant electrolyte is prepared in this example.

[0080] A high temperature resistant electrolyte differs from Example 5 in that the NaBOB derivative is prepared in this comparative example.

[0081] The preparation of the NaBOB derivative differs from that of Example 5 in that an equal molar amount of oxalic acid is used to replace 4-(2-carboxyethyl)-4-nitropimelate.

[0082] The preparation of a high temperature sodium ion battery is the same as that in Example 1.

[0083] Test Example 1:

[0084] Infrared characterization

[0085] The test was conducted using a Fourier infrared spectrometer with a test range of 500~4000cm -1 .

[0086] The above test was performed on NaBOB and the NaBOB derivative prepared in Example 1. The results are as follows: Figure 1 As shown in the figure, compared with the infrared test results of NaBOB, the infrared spectrum of the NaBOB derivative prepared in Example 1 is 1766cm -1 The infrared characteristic absorption peaks of carbonyl groups near 1640 cm -1 Nearby-COO - The infrared characteristic absorption peak was significantly enhanced. The above results indicate that the NaBOB derivative in Example 1 was successfully prepared.

[0087] The above infrared test was performed on the battery separators prepared in Example 1 and Example 7. The results are as follows: Figure 2 As shown in the figure, compared with the infrared test results of the battery separator prepared in Example 1, the infrared spectrum of the battery separator prepared in Example 7 shows that the infrared spectrum at 1190 cm -1 、630cm -1 、525cm -1 The infrared characteristic absorption peak of the sulfonic acid group appears nearby. The above results indicate that the battery separator in Example 7 was successfully prepared.

[0088] Test Example 2:

[0089] Conductivity measurement

[0090] The test was conducted using a DDJS-307 conductivity meter. Sample preparation: The test sample was dissolved in propylene carbonate at a concentration of 0.025 mol / L and fully dissolved by ultrasonic cleaning.

[0091] The above test was performed on NaBOB and its NaBOB derivatives prepared in Examples 1 to 3 and Comparative Example 1. The results are shown in Table 1:

[0092] Table 1 Conductivity test results

[0093] sample Conductivity (σ mS / cm) Example 1 0.184 Example 2 0.173 Example 3 0.181 Comparative Example 1 0.093 NaBOB 0.072

[0094] From the data analysis in Table 1, it can be seen that the ionic conductivity of the NaBOB derivative prepared in Example 1 of the present invention in propylene carbonate is significantly better than that of Comparative Example 1 and NaBOB, indicating that the use of 4-(2-carboxyethyl)-4-nitropimelic acid to dope modified NaBOB to prepare NaBOB derivatives can effectively improve the structure of the NaBOB derivatives, thereby enhancing their conductive properties.

[0095] Test Example 3:

[0096] Porosity and liquid absorption determination

[0097] The membrane sample was immersed in n-butanol or electrolyte (1M NaPF6 / EC-DEC (v / v, 1:1)) and taken out after 2 hours. The porosity was calculated according to the following formula:

[0098] Porosity / %=(M1-M0) / (ρ b V d )×100%

[0099] Where M0 and M1 are the masses of the membrane sample before and after immersion, respectively, and ρ b is the density of n-butanol, V d is the volume of the diaphragm sample.

[0100] The liquid absorption rate is calculated according to the following formula:

[0101] Liquid absorption rate / %=(m1-m0) / m0×100%

[0102] Where m0 and m1 are the masses of the diaphragm sample before and after being immersed in the electrolyte for 2 h.

[0103] The above test was performed on the battery separators prepared in Example 1 and Example 7, and the results are shown in Table 2:

[0104] Table 2 Porosity and liquid absorption test results

[0105] sample Porosity (%) Liquid absorption rate (%) Example 1 81.3% 428.17 Example 7 78.6% 323.45

[0106] From the data analysis in Table 2, it can be seen that the porosity and liquid absorption rate of the battery separator prepared in Example 7 of the present invention are significantly higher than those in Example 1, indicating that the use of 4,4'-dihydrazinostilbene-2,2'-disulfonic acid as a polymerization monomer and compounding with other raw materials to prepare a battery separator can effectively improve the pores and network structure of the separator, thereby improving its porosity and liquid absorption performance.

[0107] Thermal stability test

[0108] The test was carried out using a thermogravimetric-differential scanning calorimeter. The temperature at which the weight loss was 5% was taken as the thermal decomposition temperature of the material.

[0109] The above test was performed on the battery separators prepared in Example 1 and Example 7. The results are as follows: Figure 3 As shown in the figure, it can be seen that the thermal decomposition temperature of the battery separator prepared in Example 7 is higher than that in Example 1, indicating that the use of 4,4'-dihydrazinostilbene-2,2'-disulfonic acid as a polymerization monomer and compounding with other raw materials to prepare the battery separator can further improve the high temperature resistance of the battery separator.

[0110] Test example 4:

[0111] Battery performance characterization

[0112] The test methods are all conventional methods that can be understood by those skilled in the art.

[0113] The sodium ion batteries prepared in Comparative Example 1 and Examples 1 to 8 were tested for cycle life, rate performance, and high temperature operation performance. The results are shown in Table 3:

[0114] Table 3 Battery performance test results

[0115] sample Cycle life (2000 cycles at room temperature, capacity retention, 0.2C rate) Capacity retention rate after 600 cycles at 55℃ (%) Example 1 90.3 92.5 Example 2 91.0 92.7 Example 3 90.5 92.3 Example 4 85.1 87.0 Example 5 87.2 89.8 Example 6 83.7 85.7 Example 7 92.8 94.1 Example 8 85.6 87.3 Comparative Example 1 86.3 88.4

[0116] From the data analysis in Table 3, it can be seen that the cycle life and high-temperature capacity retention rate of the sodium ion battery prepared in Example 1 are significantly higher than those in Example 4, Example 5 and Example 6, and the effects of Example 4 and Example 5 are better than that of Example 6, and the effect of Example 5 is better than that of Comparative Example 1, indicating that the use of 4-(2-carboxyethyl)-4-nitroheptanedioic acid to dope modified NaBOB to prepare NaBOB derivatives, add them to the electrolyte as sodium salts, and then use them in the preparation of batteries, can effectively improve the cycle stability and high-temperature performance of the battery; at the same time, adding 4-((trimethylsilyl)ethynyl)morpholine to the electrolyte can also effectively improve the cycle stability and high-temperature performance of the battery, and under the condition that the NaBOB derivatives and 4-((trimethylsilyl)ethynyl)morpholine exist at the same time, a synergistic enhancement effect can be achieved, and the improvement effect of battery performance is better. The effect of Example 7 is significantly better than that of Example 1, and the effect of Example 8 is significantly better than that of Example 6, indicating that the use of 4,4'-dihydrazinostilbene-2,2'-disulfonic acid as a polymerization monomer and compounded with other raw materials to prepare a battery separator can be applied to the preparation process of sodium ion batteries. The electrochemical properties of the battery can be further improved, and its cyclic performance and high-temperature performance are significantly improved.

[0117] The conventional techniques in the above embodiments are prior arts known to those skilled in the art, and thus will not be described in detail here.

[0118] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing a NaBOB derivative used as an electrolyte sodium salt, comprising: The organic acid 4-(2-carboxyethyl)-4-nitropimelic acid, boric acid and sodium hydroxide are mixed, ground by manual dry grinding, then placed in a crucible, transferred to an oven and kept at 110-120° C. for 5-7 hours, then continued to heat to 240-250° C. for 5-7 hours, then cooled to room temperature, washed with anhydrous ethanol, and vacuum dried at 50-60° C. for 4-6 hours to obtain a NaBOB derivative; The molar ratio of the organic acid, boric acid and sodium hydroxide is 1.8-2.2:1:

1.

2. A high temperature resistant electrolyte comprising a NaBOB derivative used as an electrolyte sodium salt prepared by the method of claim 1.

3. A high temperature resistant electrolyte according to claim 2, characterized in that: The high temperature resistant electrolyte comprises an organic mixed solvent and a high temperature additive; the high temperature additive comprises 4-((trimethylsilyl)ethynyl)morpholine.

4. A high temperature resistant electrolyte according to claim 3, characterized in that: The concentration of the electrolyte sodium salt in the high temperature resistant electrolyte is 0.8-1.2 mol / L; the concentration of the high temperature additive is 1.5-3 wt %.

5. A high temperature sodium ion battery comprising the high temperature resistant electrolyte according to claim 3.

6. The battery according to claim 5, characterized in that: The battery also includes a positive electrode material, a negative electrode material and a battery separator.

7. The battery according to claim 6, wherein the method for preparing the battery separator comprises: Take 4,4'-dihydrazinostilbene-2,2'-disulfonic acid and add NMP to dissolve, add 3,3,4,4-biphenyltetracarboxylic dianhydride, add crosslinking agent BTMSPA after the solution becomes transparent, stir vigorously for 20-40 minutes, add dehydrating agent acetic anhydride and catalyst pyridine, remove bubbles by ultrasound, and obtain a polymer solution; then coat it on an automatic coating machine, and obtain a polymer wet gel film after 8-12 minutes. After placing it for 0.5-1.5 days, immerse it in a mixed solvent of NMP and acetone, immerse it for 24-30 hours, and change the solvent every 12 hours; then immerse it in an acetone solution, immerse it for 24-30 hours, and change the solvent every 12 hours; then place it in a supercritical drying device, flatten and fix the membrane with a wire plate, adjust the carbon dioxide to a supercritical state, and dry it at 50-60°C and 10-12MPa for 2-3 days, and take it out to obtain a battery separator.

8. Use of the NaBOB derivative obtained by the preparation method according to claim 1 in preparing an electrolyte or a battery.

9. Use of the high temperature resistant electrolyte according to claim 2 in preparing a battery for energy storage.

10. A vehicle comprising the battery according to claim 5.

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