Low-temperature-resistant electrolyte for alkaline battery and preparation method of low-temperature-resistant electrolyte

Abstract

The invention discloses a low-temperature-resistant electrolyte for an alkaline battery and a preparation method of the low-temperature-resistant electrolyte, and relates to the technical field of electrolytes. The invention discloses a fluorine-containing cleaning agent, which is prepared from the following raw materials in parts by mass: 11 to 13 parts of glycerol triacetate, 100 to 150 parts of potassium hydroxide aqueous solution, 1 to 5 parts of fluorine-containing additive and 21.3 to 28 parts of organic dispersion liquid, the organic dispersion liquid is prepared from ethylene glycol, tetrabutyl ammonium trifluoromethanesulfonate, a hybrid nanosheet and glycerol triacetate. The hybrid nanosheets prepared from hexagonal boron nitride, ceric ammonium nitrate, urea, polyethylene glycol 400 and other components effectively improve the ionic conductivity and cycle stability retention rate of the electrolyte at low temperature; due to the introduction of the glycerol triacetate, the fluorine-containing additive and other components, the performance retention rate of the electrolyte at the low temperature is further improved, and meanwhile the viscosity of the electrolyte at the low temperature is reduced. Therefore, the method has a wider application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolytes, and in particular to a low-temperature resistant electrolyte for alkaline batteries and a preparation method thereof. Background Art

[0002] Alkaline aqueous batteries are a type of energy storage system that uses alkaline aqueous solutions as electrolytes and metals or metal oxides as electrode materials. They are characterized by high safety, low cost, and environmental friendliness, and are widely used in large-scale energy storage, portable power supplies, and other fields. The electrolyte of alkaline aqueous batteries is primarily composed of solvents, electrolytes, and additives, and its liquid temperature operating range is narrow, hindering its application under low-temperature conditions. Although increasing the electrolyte concentration can correspondingly lower its freezing point based on colligative properties, high alkaline electrolyte concentrations accelerate passivation and corrosion of metal electrodes, resulting in poor stability of zinc-based batteries.

[0003] To address these issues, researchers have proposed adding antifreeze to aqueous battery systems, effectively lowering the freezing point of the electrolyte. However, in practice, these electrolytes still suffer from significant degradation of electrochemical performance and a significant increase in viscosity at low temperatures. Therefore, the low-temperature resistance of existing alkaline aqueous battery electrolytes remains to be improved. Summary of the Invention

[0004] The purpose of the present invention is to provide a low-temperature resistant electrolyte for alkaline batteries and a preparation method thereof, to solve the following technical problems: Existing alkaline aqueous battery electrolytes still have the problem of poor performance maintenance ability at low temperatures.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A low-temperature resistant electrolyte for alkaline batteries, comprising the following raw materials by weight: 11-13 parts of glycerol triacetate, 100-150 parts of potassium hydroxide aqueous solution, 1-5 parts of a fluorine-containing additive, and 21.3-28 parts of an organic dispersion; The organic dispersion is prepared from ethylene glycol, tetrabutylammonium trifluoromethanesulfonate, hybrid nanosheets and glycerol triacetate.

[0006] Preferably, the preparation method of the organic dispersion is as follows: Tetrabutylammonium trifluoromethanesulfonate was added to ethylene glycol and stirred at 40° C. for 2-3 hours, then the hybrid nanosheets were added and ultrasonically dispersed for 30-60 minutes, and then glycerol triacetate was added and stirred for 20-30 minutes to obtain an organic dispersion.

[0007] Preferably, the mass ratio of the ethylene glycol, tetrabutylammonium trifluoromethanesulfonate, hybrid nanosheets, and glycerol triacetate is 13-17:3.8-4:1.2-1.5:3.3-5.5.

[0008] Preferably, the preparation method of the hybrid nanosheets is as follows: A1: Add concentrated sulfuric acid dropwise to concentrated nitric acid at 1-2 mL / min at 0-5°C, mix thoroughly, add hexagonal boron nitride, and ultrasonically treat at 700-800 W and 35-40 kHz for 2-3 hours at 55-65°C. Wash by centrifugation until neutral, then perform plasma treatment. Finally, vacuum dry at 55-65°C for 6-8 hours to obtain pretreated boron nitride. A2: Add cerium ammonium nitrate and urea to deionized water at 38-42°C and stir for 20-30 minutes to obtain a mixed dispersion; A3: Add anhydrous ethanol to deionized water to pre-treat the boron nitride and perform ultrasonic treatment at a power of 450-500 W and a frequency of 35-40 kHz for 30-60 minutes. Then, add polyethylene glycol 400 and stir at 58-62°C for 30-50 minutes. Then, add the mixed dispersion dropwise at a rate of 1-2 g / min. Then, stir and reflux at 78-80°C for 6-7 hours. Finally, centrifuge, wash the precipitate with anhydrous ethanol 3-5 times, and vacuum dry at 75-80°C for 11-15 hours to obtain a boron nitride complex. A4: The boron nitride composite is subjected to high-temperature crystallization treatment to obtain hybrid nanosheets.

[0009] Preferably, the ratio of concentrated sulfuric acid, concentrated nitric acid, and hexagonal boron nitride in A1 is 60-72 mL: 30-36 mL: 7-8.5 g; The atmosphere during the plasma treatment described in A1 is a combined gas atmosphere of hydrogen and nitrogen; The power of the plasma treatment described in A1 is 280-300 W, the pressure is 45-50 Pa, the argon gas flow rate is 60-75 sccm, the oxygen gas flow rate is 20-25 sccm, and the duration is 15-20 minutes.

[0010] Preferably, the mass ratio of deionized water, cerium ammonium nitrate, and urea in A2 is 100-120:5-7:7-10.8.

[0011] Preferably, the usage ratio of deionized water, anhydrous ethanol, pretreated boron nitride, polyethylene glycol 400, and mixed dispersion in A3 is 50-70 mL: 50-70 mL: 5-7 g: 0.25-0.35 g: 112-137.8 g.

[0012] Preferably, the atmosphere during the high temperature crystallization treatment in A4 is a combined gas atmosphere of hydrogen and nitrogen; During the high temperature crystallization treatment described in A4, the hydrogen gas flow rate is 5-10 sccm and the nitrogen gas flow rate is 90-95 sccm; The temperature rise program during the high temperature crystallization treatment in A4 is to first rise to 500-550°C at 2-5°C / min, then keep at 500-550°C for 2-3h, and then cool to 20-40°C at 1-3°C / min.

[0013] Preferably, the concentration of the potassium hydroxide aqueous solution is 2-4 mol / L; The fluorine-containing additive is any one of perfluorotriethylamine, perfluorotributylamine and perfluorotripropylamine.

[0014] A method for preparing a low-temperature resistant electrolyte for alkaline batteries comprises the following steps: Glycerol triacetate and a fluorine-containing additive are added to a potassium hydroxide aqueous solution and stirred for 10-30 minutes. Then, an organic dispersion is added dropwise at a rate of 1-3 g / min and stirred for 30-60 minutes. Finally, degassing is carried out at -0.1 MPa for 30-60 minutes to obtain a low-temperature resistant electrolyte for alkaline batteries.

[0015] Beneficial effects of the present invention: The present invention provides a low-temperature resistant electrolyte for alkaline batteries and a preparation method thereof. The present invention effectively improves the performance maintenance capability of the electrolyte for alkaline batteries at low temperatures through the following method.

[0016] (1) During the preparation of the hybrid nanosheets of the present invention, concentrated sulfuric acid-concentrated nitric acid treatment and plasma treatment introduce a large number of polar functional groups such as hydroxyl and carboxyl groups on the surface of hexagonal boron nitride, thereby enhancing its compatibility with polar solvents and avoiding the increase in electrolyte viscosity caused by its aggregation. The high thermal conductivity of hexagonal boron nitride can accelerate the heat transfer inside the electrolyte at low temperatures, reduce local concentration polarization, and maintain the stability of ion transport. The cerium-based nanoparticles generated by the reaction of ammonium cerium nitrate and urea will be uniformly loaded on the surface of the boron nitride sheet, forming abundant oxygen vacancies and cerium pairs on its surface, which can catalyze the dissociation of water molecules in the electrolyte, promote the solvation and shelling process of potassium ions, and reduce the activation energy of ion migration at low temperatures; they will also form a coordination effect with the hydroxide in the potassium hydroxide electrolyte, stabilize the transmission path of potassium ions, and reduce the blockage of ion channels by solvent molecule crystallization at low temperatures. After high-temperature crystallization treatment, the defects of the boron nitride sheet can be repaired, and the cerium-based compound may be partially reduced to a low-valent state, thereby enhancing its electrostatic interaction with potassium ions and further reducing the resistance to ion migration. The polar functional groups of the hybrid nanosheets can form hydrogen bonding networks with ethylene glycol and glycerol triacetate, weakening the van der Waals forces between solvent molecules, making it more difficult for the electrolyte to crystallize at low temperatures and reducing its supercooling. The "lubricating effect" of the two-dimensional sheets reduces frictional resistance between solvent molecules and simultaneously reduces the viscosity increase of the electrolyte at low temperatures. The oxygen vacancies in the cerium-based compounds serve as "fast transport sites" for potassium ions, forming a conductive path similar to an "ion highway." The high surface area of ​​the plasma-treated boron nitride sheets provides an interface for ion adsorption and desorption, shortening ion diffusion distances and compensating for the weakened thermal motion at low temperatures. Once uniformly dispersed in the electrolyte, the hybrid nanosheets preferentially adsorb on the electrode surface, forming a composite interfacial film rich in cerium-oxygen bonds and boron nitride sheets. The strong coordination between the cerium-oxygen bonds and potassium ions reduces interfacial charge transfer resistance. The chemical inertness of the boron nitride sheets prevents side reactions between the electrolyte and the electrode, maintaining interfacial stability. The coordination effect between nanosheets and water can reduce the content of free water molecules, inhibit the growth of ice crystals at low temperatures, and avoid the risk of short circuit caused by ice crystals piercing the electrodes.

[0017] (2) The cation and anion of the tetrabutylammonium trifluoromethanesulfonate of the present invention are both large and weakly coordinated ions. Their solvation shells are relatively thin at low temperatures, resulting in low ion migration resistance. Its introduction can supplement the carrier concentration and improve ionic conductivity. The addition of tetrabutylammonium trifluoromethanesulfonate colligatively lowers the freezing point of the electrolyte, and synergistically with potassium hydroxide can further lower the freezing point, delaying ice crystal formation.

[0018] (3) Glycerol triacetate forms a low-melting system with solvents such as ethylene glycol, lowering the freezing point of the electrolyte; its ester group can form an adsorption layer on the surface of the zinc electrode, inhibiting the growth of zinc dendrites and improving the structural stability during low-temperature cycling; the addition of glycerol triacetate can reduce the viscosity of the system through the dilution effect and reduce the resistance to ion migration. The weaker intermolecular interaction also helps ions to detach from the solvation sheath, improving ionic conductivity, and thus improving the charge and discharge efficiency and capacity retention rate of the battery at low temperatures.

[0019] (4) The high stability of the perfluorotriethylamine molecule in the present invention helps maintain the stability of the electrolyte composition at low temperatures, avoiding the decrease in ion conductivity due to changes in composition; its fluorinated group also has a low dielectric constant and strong electron-withdrawing ability, which can form a weak solvation effect with cations such as potassium ions, promote the dissociation of potassium hydroxide in the electrolyte, and increase the free ion concentration; its molecular structure can also participate in adjusting the composition of the solvation sheath, reducing the activation energy of ion migration, thereby maintaining a high ion conduction efficiency at low temperatures. The low surface energy characteristics of perfluorotriethylamine can reduce the interfacial tension between the electrolyte and the electrode material, enhance the electrolyte's ability to penetrate the electrode pores, ensure that the electrode active material can fully contact the electrolyte at low temperatures, reduce the interfacial resistance, and improve the power density and cycle stability of the battery. Glycerol triacetate maintains the fluidity of the electrolyte by reducing the viscosity and freezing point, and perfluorotriethylamine improves the ion migration rate by optimizing the ion dissociation and solvation structure. The synergistic effect of the two can significantly improve the ionic conductivity of the electrolyte at low temperatures, avoiding a significant attenuation of the battery capacity. The flexible interfacial film formed by propylene glycol triacetate combined with the chemical stability of perfluorotriethylamine can form a "double protective layer" on the electrode surface. The former reduces the mechanical stress of the interface, and the latter inhibits chemical corrosion, thereby reducing the growth of interfacial impedance during low-temperature cycling and improving performance retention.

[0020] Therefore, the low-temperature-resistant electrolyte for alkaline batteries prepared by the present invention has excellent cycle stability, cycle stability at low temperatures and ionic conductivity, as well as a freezing point and viscosity at room temperature and low temperatures far lower than those of pure potassium hydroxide aqueous solution, and has a broader application prospect. DETAILED DESCRIPTION

[0021] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0022] Unless otherwise specified, some of the raw materials used in the following examples and comparative examples of the present invention are as follows: Polyethylene glycol 400 was purchased from Nanjing Kerunjiang Chemical Co., Ltd., CAS: 25322-68-3.

[0023] Example 1: A method for preparing a low-temperature resistant electrolyte for alkaline batteries is as follows: S1: At 0°C, 60 mL of concentrated sulfuric acid was added dropwise to 30 mL of concentrated nitric acid at a rate of 1 mL / min. After mixing, 7 g of hexagonal boron nitride was added and ultrasonic treatment was performed at 55°C for 2 h with a power of 700 W and a frequency of 35 kHz. After centrifugation and washing until neutral, plasma treatment was performed for 15 min with a power of 280 W, a pressure of 45 Pa, an argon gas flow rate of 60 sccm, and an oxygen gas flow rate of 20 sccm. Finally, vacuum drying was performed at 55°C for 6 h to obtain pretreated boron nitride. S2: Add 5 g of ammonium cerium nitrate and 7 g of urea to 100 g of deionized water at 38°C and stir for 20 min to obtain a mixed dispersion; S3: Add 50 mL of anhydrous ethanol and 5 g of pretreated boron nitride to 50 mL of deionized water and perform ultrasonic treatment at a power of 450 W and a frequency of 35 kHz for 30 minutes. Then, add 0.25 g of polyethylene glycol 400 and stir at 58°C for 30 minutes. Then, add 112 g of the mixed dispersion dropwise at a rate of 1 g / min, and stir and reflux at 78°C for 6 hours. Finally, centrifuge, wash the precipitate with anhydrous ethanol three times, and vacuum dry at 75°C for 11 hours to obtain a boron nitride complex. S4: placing the boron nitride composite in a mixed gas atmosphere with a hydrogen gas flow rate of 5 sccm and a nitrogen gas flow rate of 95 sccm and heating the mixture to 500°C at a rate of 2°C / min, maintaining the temperature for 2 hours, and then cooling the mixture to 20°C at a rate of 1°C / min to obtain hybrid nanosheets; S5: 3.8 g of tetrabutylammonium trifluoromethanesulfonate was added to 13 g of ethylene glycol and stirred at 40°C for 2 h. Then, 1.2 g of hybrid nanosheets was added and ultrasonic dispersion was performed at a power of 300 W and a frequency of 35 kHz for 30 min. Then, 3.3 g of glycerol triacetate was added and stirred for 20 min to obtain an organic dispersion. S6: Add 11 mL of glycerol triacetate and 1 g of perfluorotriethylamine to 100 g of a 2 mol / L potassium hydroxide aqueous solution and stir for 10 minutes. Then, add 21.3 g of an organic dispersion dropwise at a rate of 1 g / min and stir for 30 minutes. Finally, degas at -0.1 MPa for 30 minutes to obtain a low-temperature-resistant electrolyte for alkaline batteries.

[0024] Example 2: A method for preparing a low-temperature resistant electrolyte for alkaline batteries is as follows: S1: At 3°C, 66 mL of concentrated sulfuric acid was added dropwise to 33 mL of concentrated nitric acid at a rate of 1.5 mL / min. After mixing, 7.8 g of hexagonal boron nitride was added and ultrasonic treatment was performed at 60°C for 2.5 h at a power of 750 W and a frequency of 38 kHz. After centrifugation and washing until neutral, plasma treatment was performed for 18 min at a power of 290 W, a pressure of 48 Pa, an argon gas flow rate of 67 sccm, and an oxygen gas flow rate of 23 sccm. Finally, vacuum drying was performed at 60°C for 7 h to obtain pretreated boron nitride. S2: Add 6 g of ammonium cerium nitrate and 8.9 g of urea to 110 g of deionized water at 40°C and stir for 25 min to obtain a mixed dispersion; S3: Add 60 mL of anhydrous ethanol and 6 g of pretreated boron nitride to 60 mL of deionized water and perform ultrasonic treatment at a power of 480 W and a frequency of 38 kHz for 45 minutes. Then, add 0.3 g of polyethylene glycol 400 and stir at 60°C for 40 minutes. Then, add 124.9 g of the mixed dispersion dropwise at a rate of 1.5 g / min, and stir and reflux at 79°C for 6.5 hours. Finally, centrifuge, wash the precipitate with anhydrous ethanol four times, and vacuum dry at 78°C for 13 hours to obtain a boron nitride complex. S4: placing the boron nitride composite in a mixed gas atmosphere with a hydrogen gas flow rate of 8 sccm and a nitrogen gas flow rate of 92 sccm and heating the mixture to 530°C at a rate of 4°C / min, maintaining the temperature for 2.5 hours, and then cooling the mixture to 30°C at a rate of 2°C / min to obtain hybrid nanosheets; S5: 3.9 g of tetrabutylammonium trifluoromethanesulfonate was added to 15 g of ethylene glycol and stirred at 40°C for 2.5 h. Then, 1.4 g of hybrid nanosheets was added and ultrasonically dispersed at a power of 350 W and a frequency of 38 kHz for 45 min. Then, 4.4 g of glycerol triacetate was added and stirred for 25 min to obtain an organic dispersion. S6: Add 12 mL of propylene glycol triacetate and 3 g of perfluorotributylamine to 125 g of a 3 mol / L potassium hydroxide aqueous solution and stir for 20 minutes. Then, add 24.6 g of the organic dispersion dropwise at 2 g / min and stir for 45 minutes. Finally, degas at -0.1 MPa for 45 minutes to obtain a low-temperature-resistant electrolyte for alkaline batteries.

[0025] Example 3: A method for preparing a low-temperature resistant electrolyte for alkaline batteries is as follows: S1: At 5°C, 72 mL of concentrated sulfuric acid was added dropwise to 36 mL of concentrated nitric acid at a rate of 2 mL / min. After mixing, 8.5 g of hexagonal boron nitride was added and ultrasonic treatment was performed at 65°C for 3 h with a power of 800 W and a frequency of 40 kHz. After centrifugation and washing until neutral, plasma treatment was performed for 20 min with a power of 300 W, a pressure of 50 Pa, an argon gas flow rate of 75 sccm, and an oxygen gas flow rate of 25 sccm. Finally, vacuum drying was performed at 65°C for 8 h to obtain pretreated boron nitride. S2: Add 7 g of ammonium cerium nitrate and 10.8 g of urea to 120 g of deionized water at 42°C and stir for 30 min to obtain a mixed dispersion; S3: 70 mL of anhydrous ethanol and 7 g of pretreated boron nitride were added to 70 mL of deionized water and ultrasonically treated at a power of 500 W and a frequency of 40 kHz for 60 min. Then, 0.35 g of polyethylene glycol 400 was added and stirred at 62°C for 50 min. Then, 137.8 g of the mixed dispersion was added dropwise at a rate of 2 g / min, and then stirred and refluxed at 80°C for 7 h. Finally, the mixture was centrifuged, washed with anhydrous ethanol for 5 times, and vacuum dried at 80°C for 15 h to obtain a boron nitride complex. S4: placing the boron nitride composite in a mixed gas atmosphere with a hydrogen gas flow rate of 10 sccm and a nitrogen gas flow rate of 90 sccm and heating the mixture to 550°C at 5°C / min, holding the mixture for 3 hours, and then cooling the mixture to 40°C at 3°C / min to obtain hybrid nanosheets; S5: 4 g of tetrabutylammonium trifluoromethanesulfonate was added to 17 g of ethylene glycol and stirred at 40°C for 3 h. Then, 1.5 g of hybrid nanosheets was added and ultrasonic dispersion was performed at a power of 400 W and a frequency of 40 kHz for 60 min. Then, 5.5 g of glycerol triacetate was added and stirred for 30 min to obtain an organic dispersion. S6: Add 13 mL of glycerol triacetate and 5 g of perfluorotripropylamine to 150 g of a 4 mol / L potassium hydroxide aqueous solution and stir for 30 minutes. Then, add 28 g of the organic dispersion dropwise at 3 g / min and stir for 60 minutes. Finally, degas at -0.1 MPa for 60 minutes to obtain a low-temperature resistant electrolyte for alkaline batteries.

[0026] Comparative Example 1: Compared with Example 1, this comparative example only replaces the preparation process of S1 with "at 0°C, 60 mL of concentrated sulfuric acid was added dropwise to 30 mL of concentrated nitric acid at 1 mL / min, mixed and added 7 g of hexagonal boron nitride and ultrasonically treated at 55°C for 2 h with a power of 700 W and a frequency of 35 kHz" with "adding 7 g of hexagonal boron nitride to 100 mL of deionized water and ultrasonically treated at 55°C for 2 h with a power of 700 W and a frequency of 35 kHz". The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a low-temperature resistant electrolyte for alkaline batteries is obtained.

[0027] Comparative Example 2: Compared with Example 1, this comparative example only replaces the preparation process of S1 with "centrifugal washing to neutrality, followed by plasma treatment for 15 minutes, a power of 280 W, a pressure of 45 Pa, an argon gas flow rate of 60 sccm, and an oxygen gas flow rate of 20 sccm, and finally vacuum drying at 55°C for 6 hours" with "centrifugal washing to neutrality, followed by vacuum drying at 55°C for 6 hours." The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a low-temperature resistant electrolyte for alkaline batteries is obtained.

[0028] Comparative Example 3: Compared with Example 1, this comparative example only replaces the "hybrid nanosheets" added in the preparation process of S5 with the "pretreated boron nitride" prepared by S1. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a low-temperature resistant electrolyte for alkaline batteries is obtained.

[0029] Comparative Example 4: Compared with Example 1, this comparative example only replaces the "hybrid nanosheets" added in the preparation process of S5 with the "boron nitride composite" prepared by S3. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a low-temperature resistant electrolyte for alkaline batteries is obtained.

[0030] Comparative Example 5: Compared with Example 1, this comparative example only does not add "tetrabutylammonium trifluoromethanesulfonate" during the preparation of S5. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a low-temperature resistant electrolyte for alkaline batteries is obtained.

[0031] Comparative Example 6: Compared with Example 1, this comparative example only does not add "propylene glycol triacetate" during the preparation of S5. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a low-temperature resistant electrolyte for alkaline batteries is obtained.

[0032] Comparative Example 7: Compared with Example 1, this comparative example only does not add "propylene glycol triacetate" during the preparation of S6. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a low-temperature resistant electrolyte for alkaline batteries is obtained.

[0033] Comparative Example 8: Compared with Example 1, this comparative example only does not add "perfluorotriethylamine" during the preparation of S6. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a low-temperature resistant electrolyte for alkaline batteries is obtained.

[0034] Performance testing: Determination of ionic conductivity: The ionic conductivity (mS·cm) of the low-temperature resistant electrolyte for alkaline batteries prepared in Examples 1 to 3 and Comparative Examples 1 to 8 at -40°C was measured. -1 ), the test results are shown in Table 1; Determination of cyclic stability: The alkaline batteries prepared in Examples 1 to 3 of the present invention and Comparative Examples 1 to 8 were assembled into rechargeable zinc batteries using a low-temperature-resistant electrolyte. The batteries were then cycled 500 times at 0.2C, 25°C, and -40°C, respectively. The capacity retention (%) after the cycles was measured to reflect the cycling stability of the electrolyte. The test results are shown in Table 1. Determination of viscosity: The viscosity (mPa·s) of the low-temperature-resistant electrolytes for alkaline batteries prepared in Examples 1 to 3 and Comparative Examples 1 to 8 at 25°C and -40°C was measured. The test results are shown in Table 1. Determination of freezing point: The freezing points (° C.) of the low-temperature-resistant electrolytes for alkaline batteries prepared in Examples 1 to 3 and Comparative Examples 1 to 8 were measured. The test results are shown in Table 1.

[0035] Table 1: Performance test results of Examples 1-3 and Comparative Examples 1-8

[0036] Data Analysis: As can be seen from Table 1, the low-temperature-resistant electrolyte for alkaline batteries prepared in the examples of the present invention has excellent cycle stability, cycle stability at low temperatures, and ionic conductivity, as well as a freezing point and viscosity at room temperature and low temperature that are far lower than those of pure potassium hydroxide aqueous solution.

[0037] The above is a detailed description of an embodiment of the present invention. However, the content described is only a preferred embodiment of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A low-temperature resistant electrolyte for alkaline batteries, characterized in that: The method comprises the following raw materials by weight: 11-13 parts of glycerol triacetate, 100-150 parts of potassium hydroxide aqueous solution, 1-5 parts of fluorine-containing additive, and 21.3-28 parts of organic dispersion; The organic dispersion is prepared from ethylene glycol, tetrabutylammonium trifluoromethanesulfonate, hybrid nanosheets and glycerol triacetate.

2. The low-temperature resistant electrolyte for alkaline batteries according to claim 1, characterized in that The preparation method of the organic dispersion is as follows: Tetrabutylammonium trifluoromethanesulfonate was added to ethylene glycol and stirred at 40° C. for 2-3 hours, then the hybrid nanosheets were added and ultrasonically dispersed for 30-60 minutes, and then glycerol triacetate was added and stirred for 20-30 minutes to obtain an organic dispersion.

3. The low-temperature resistant electrolyte for alkaline batteries according to claim 2, characterized in that The mass ratio of the ethylene glycol, tetrabutylammonium trifluoromethanesulfonate, hybrid nanosheets and glycerol triacetate is 13-17:3.8-4:1.2-1.5:3.3-5.

5.

4. The low-temperature resistant electrolyte for alkaline batteries according to claim 1, characterized in that The preparation method of the hybrid nanosheet is as follows: A1: Add concentrated sulfuric acid dropwise to concentrated nitric acid at 0-5°C, mix thoroughly, add hexagonal boron nitride, and ultrasonicate at 55-65°C for 2-3 hours. Wash by centrifugation until neutral, then perform plasma treatment, and finally vacuum dry to obtain pretreated boron nitride. A2: Add cerium ammonium nitrate and urea to deionized water at 38-42°C and stir for 20-30 minutes to obtain a mixed dispersion; A3: Add anhydrous ethanol to deionized water to pre-treat the boron nitride and perform ultrasonic treatment for 30-60 minutes. Then, add polyethylene glycol 400 and stir at 58-62°C for 30-50 minutes. Then, add the mixed dispersion dropwise, stir and reflux at 78-80°C for 6-7 hours. Finally, centrifuge, wash the precipitate, and vacuum dry to obtain a boron nitride complex. A4: The boron nitride composite is subjected to high-temperature crystallization treatment to obtain hybrid nanosheets.

5. The low-temperature resistant electrolyte for alkaline batteries according to claim 4, characterized in that The ratio of concentrated sulfuric acid, concentrated nitric acid, and hexagonal boron nitride in A1 is 60-72 mL: 30-36 mL: 7-8.5 g; The atmosphere during the plasma treatment described in A1 is a mixed gas atmosphere of hydrogen and nitrogen; The plasma treatment described in A1 has a power of 280-300 W, a pressure of 45-50 Pa, an argon gas flow rate of 60-75 sccm, an oxygen gas flow rate of 20-25 sccm, and a duration of 15-20 min.

6. The low-temperature resistant electrolyte for alkaline batteries according to claim 4, characterized in that The mass ratio of deionized water, cerium ammonium nitrate and urea in A2 is 100-120:5-7:7-10.

8.

7. The low-temperature resistant electrolyte for alkaline batteries according to claim 4, characterized in that The usage ratio of deionized water, anhydrous ethanol, pretreated boron nitride, polyethylene glycol 400, and mixed dispersion in A3 is 50-70 mL: 50-70 mL: 5-7 g: 0.25-0.35 g: 112-137.8 g.

8. The low-temperature resistant electrolyte for alkaline batteries according to claim 4, characterized in that The atmosphere during the high temperature crystallization treatment described in A4 is a mixed gas atmosphere of hydrogen and nitrogen; During the high temperature crystallization treatment described in A4, the hydrogen gas flow rate is 5-10 sccm and the nitrogen gas flow rate is 90-95 sccm; The temperature rise program during the high temperature crystallization treatment in A4 is to first rise to 500-550°C at 2-5°C / min, then keep at 500-550°C for 2-3h, and then cool to 20-40°C at 1-3°C / min.

9. The low-temperature resistant electrolyte for alkaline batteries according to claim 1, characterized in that The concentration of the potassium hydroxide aqueous solution is 2-4 mol / L; The fluorine-containing additive is any one of perfluorotriethylamine, perfluorotributylamine and perfluorotripropylamine.

10. A method for preparing a low-temperature resistant electrolyte for alkaline batteries according to any one of claims 1 to 9, characterized in that: The following steps are involved: Glycerol triacetate and a fluorine-containing additive are added to a potassium hydroxide aqueous solution and stirred for 10-30 minutes, then an organic dispersion is added dropwise and stirred for 30-60 minutes, and finally degassed at -0.1 MPa for 30-60 minutes to obtain a low-temperature resistant electrolyte for alkaline batteries.

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