Preparation method of titanium dioxide for battery electrolyte with high ionic conductivity

Abstract

The invention discloses a preparation method of titanium dioxide for high-ionic-conductivity battery electrolyte, and relates to the technical field of inorganic material preparation, and the preparation method comprises the following steps: S1, raw material mixing and esterification reaction; s2, reflux reaction and dehydration reaction; s3, neutralizing acidity and carrying out liquid-liquid layering; s4, double distillation purification; s5, performing ultrasonic-assisted dispersion; s6, carrying out sol-gel conversion; s7, carrying out gelation and vacuum drying; s8, performing low-temperature nitrogen presintering; s9, high-temperature oxidation calcination; and S10, performing nanocrystallization and interface modification. Through low-temperature nitrogen presintering and high-temperature oxidation calcination, the low-temperature presintering avoids structural damage, the high-temperature calcination optimizes the crystal performance, the purity, crystallinity and stability are remarkably improved, the high activity and long service life are achieved, and a key material support is provided for the fields of energy, environmental protection and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of inorganic material preparation, and in particular to a method for preparing titanium dioxide for high ion conductivity battery electrolyte. Background Art

[0002] Solid-state batteries are a new generation of energy storage technology. The performance of their core component, the solid electrolyte, directly affects the battery's energy density, cycle life, and safety. Currently, mainstream solid-state electrolyte materials include sulfides, oxides, and polymers, but all have significant flaws. Titanium dioxide, due to its high chemical stability and low cost, is considered a potential solid-state electrolyte material, aiming to significantly improve the ionic conductivity and interfacial stability of solid-state batteries.

[0003] However, existing traditional solid electrolyte materials have problems such as low ionic conductivity, high interfacial impedance, and complex preparation processes. In particular, when titanium dioxide is used as an electrolyte material, its performance is often limited due to insufficient crystallinity, residual impurities, or uneven particle size distribution. Insufficient crystallinity will lead to an increase in amorphous regions within the material, disordered atomic arrangement, and hindering the orderly migration of ions. Moreover, the lattice of low-crystallinity materials is easily distorted under high temperature or high electric field, resulting in a shortened material life. Uneven particle size distribution leads to uneven pore distribution, forming "dead zones" between large particles, and also prolonging the ion transmission path.

[0004] There are related invention patents regarding the preparation of titanium dioxide, as follows: Chinese patent application number: CN201910286323.4, the name of the invention patent is:, the invention relates to the field of chemical technology, in particular to a method for preparing nano-scale titanium dioxide, comprising the following steps: S1: take titanium ore, place it in a 121°C high-pressure steam sterilizer for treatment for 30-45 minutes to obtain a treated product; S2: take the treated product obtained in S1, add 4-5 times the chloride equivalent to the treated product, stir for 1-2 hours, and obtain a treated liquid; S3: take the treated liquid obtained in S2, filter, and dry the filtrate to obtain a dried product; S4: take the dried product obtained in S3 and steel balls, add silicon dioxide at the same time, place it in a high-energy ball mill and grind for 18-24 hours to obtain nano-scale titanium dioxide; the method for preparing nano-titanium dioxide of the present invention combines physical and chemical methods, the preparation method is simple and convenient, and the purity and yield are high.

[0005] However, while the aforementioned existing patents combine physical and chemical methods to make titanium dioxide preparation simple and convenient, the rapid decomposition of organic matter can easily lead to cracking and uneven porosity in the material. Cracking directly reduces the effective surface area, thereby reducing catalytic activity. Furthermore, cracking increases the material's brittleness, making it prone to breakage under stress. Uneven porosity can affect the efficiency of ion or molecular transport, and uneven pore distribution can also lead to inconsistent catalyst surface reactivity. Summary of the Invention

[0006] The purpose of the present application is to provide a method for preparing titanium dioxide for battery electrolyte with high ionic conductivity, so as to solve the problem in the prior art that rapid decomposition of organic matter easily leads to material cracking or uneven porosity.

[0007] The present invention achieves a highly efficient and controllable reaction of the titanium source through composite ligands and staged hydrolysis, reducing impurity generation. Furthermore, a low-temperature two-step calcination method is used to obtain highly crystalline titanium dioxide at low energy consumption.

[0008] A method for preparing titanium dioxide for high ionic conductivity battery electrolyte comprises the following steps: S1, raw material mixing and esterification reaction: titanic acid powder, excess n-butanol and a small amount of concentrated sulfuric acid are added to a three-necked flask; S2, reflux reaction and dehydration reaction: assemble a water separator and condenser, heat the oil bath to 120-140°C, and maintain reflux for 6-12 hours; S3, neutralize the acidity and separate the liquid and liquid layers: wait for the reaction liquid to cool to room temperature, slowly add dilute NaOH solution or solution; S4, double distillation purification: recover excess n-butanol by distillation at atmospheric pressure, switch to reduced pressure distillation, and then collect colorless and transparent tetrabutyl titanate at 180-200°C. The purity of the purified product is ≥99%; S5, ultrasound-assisted dispersion: tetrabutyl titanate and ethanolamine were dissolved in anhydrous ethanol; S6, sol-gel conversion: slowly add aqueous acetic acid solution dropwise in a 50-70°C water bath at a rate of 2-3 mL / min; S7, gelation and vacuum drying: the sol was sealed and allowed to stand for 24 h to complete gelation and obtain a translucent wet gel; S8, low-temperature nitrogen pre-calcination: the dry gel powder is evenly spread in the crucible body, the crucible body is placed in a tube furnace, high-purity nitrogen is introduced, the temperature is increased to 300-400°C at 2-5°C / min, and calcined for 2h; S9, high-temperature oxidation calcination: the intermediate product after pre-calcination and cooling is re-charged into the furnace, switched to an oxygen / nitrogen mixed gas, and heated to 500-600°C at 3-10°C / min, and calcined for 4 hours; S10, nano-sizing and interface modification: The calcined product was crushed to 101-200 nm using a supersonic jet mill.

[0009] As a further improvement of the present invention, in the steps S1-S2, the mol ratio of the excess n-butanol is 1:4-6, the concentrated sulfuric acid accounts for 1-3% of the total mass, the concentrated sulfuric acid promotes esterification as a catalyst, the mixing is mechanically stirred to fully contact metatitanic acid powder, excess n-butanol and a small amount of concentrated sulfuric acid, the water separator is used to separate the moisture generated in the reaction in real time, and heating is stopped when the water amount of the water separator is stable. The water amount of the water separator is stabilized for a time of about 4-6 hours, and the water separator is used to ensure that the esterification reaction is complete. The water separator can remove the moisture generated by the reaction in real time, break the chemical equilibrium, and promote the reaction to proceed in the direction of generating esters, thereby improving yield. The excess n-butanol in the molar ratio of 1:4-6 can make the reactant concentration ratio away from the equilibrium constant, thereby improving the yield of esters.

[0010] As a further improvement of the present invention, in steps S3-S4, the dilute NaOH solution or The solution needs to be added dropwise until the pH value is 7, the dilute NaOH solution or The solution is used to neutralize the unreacted acidic substance, and the neutralized solution is transferred to a separating funnel. The separating funnel is used for standing and stratifying, retaining the upper organic phase. The boiling point of the excess n-butanol is 117 ° C, and the vacuum degree of the reduced pressure distillation is 0.09 MPa. Removing acidic impurities and reducing the residual inorganic salts or acidic substances in the product can improve product purity. The separating funnel can effectively separate the organic phase and the aqueous phase, reduce the dissolution loss of the product in the aqueous phase, and improve the recovery rate. The boiling point of n-butanol is much higher than that of water. It is easy to separate from water in the reduced pressure distillation, which is convenient for recovering the unreacted excess n-butanol and reducing the cost of raw materials.

[0011] As a further improvement of the present invention, in steps S5-S7, the tetrabutyl titanate is 10 g, the ethanolamine is 2 g, the anhydrous ethanol is 50 mL, the ethanolamine is used as a chelating agent to stabilize titanium ions, the pH value of the acetic acid aqueous solution is 4, the volume ratio of acetic acid to water in the acetic acid aqueous solution is 1:5, and the acetic acid aqueous solution is continuously stirred until the solution turns from turbid to clear, and the continuous stirring forms a uniform The sol is vacuum-dried using a vacuum freeze dryer at -50°C and a vacuum of <1 Pa for 48 hours to obtain a loose, porous xerogel. The xerogel is then crushed and passed through a 200-mesh sieve. A pH-4 acetic acid aqueous solution accelerates the hydrolysis of tetrabutyl titanate, while the acidic conditions catalyze the polycondensation reaction, forming a gel with a three-dimensional network structure. Compared to neutral conditions, the reaction rate is increased by 3-5 times.

[0012] As a further improvement of the present invention, in steps S8-S9, the flow rate of the high-purity nitrogen is 100 mL / min, and the low-temperature nitrogen pre-burning is used to remove organic matter to form amorphous The precursor, oxygen accounts for 8% in the oxygen / nitrogen mixture, the flow rate of the oxygen / nitrogen mixture is 200mL / min, and the high temperature oxidation calcination is used to improve the crystallinity. Two-step heating, through low temperature nitrogen pre-burning and slow temperature increase to decompose organic matter, avoid rapid thermal decomposition to produce gas shock and cause structural collapse, and then through high temperature calcination to make The crystals grow completely, which reduces surface defects.

[0013] As a further improvement of the present invention, in step S10, the feed pressure of the supersonic airflow mill is 0.6 MPa, the calcined product after the pulverization is immersed in a lithium phosphate solution with a concentration of 0.1-0.5 mol / L, the immersion is used to enhance the interfacial ion transmission capacity, and the vacuum drying is performed after the immersion. The vacuum drying will obtain a lithium phosphate-coated Nanoparticles. Coating inhibits The lattice expands, and the volume change after cycling is less than 4%, reducing the capacity decay rate by 60%. Moreover, the structure is stable at high temperatures of 600°C, with no phase change or decomposition, significantly improving safety.

[0014] As a further improvement of the present invention, the outer surface of the crucible body is provided with four securing blocks, each of which is fixedly connected to a fixing rod at its top end. The top ends of the four fixing rods are fixedly connected to a top plate, and the bottom side of the top plate is fixedly connected to a powder inlet trough. The securing blocks fit closely to the crucible body, allowing the entire grinding powder spreading device to hover within the crucible body, thereby achieving a fixed position.

[0015] As a further improvement of the present invention, a rotating motor is fixedly connected to the center of the bottom end of the top plate, a conical block is fixedly connected to the bottom output end of the conical block, the bottom end of the conical block is fixedly connected to a meshing wheel 1, the bottom end of the meshing wheel 1 is fixedly connected to a connecting rod, the bottom end of the connecting rod is fixedly connected to a threaded grinding block, the bottom end of the threaded grinding block is fixedly connected to a rotating disk, the outer portion of the rotating disk is rotatably connected to a cylindrical frame, and the outer surface of the cylindrical frame is provided with a plurality of downwardly inclined powder outlets. Through the rotation of the threaded grinding block, the internal agglomerates of the dry gel powder can be ground into powder, and the powder can be evenly spread into the crucible body through the powder outlet.

[0016] As a further improvement to the present invention, a funnel trough is fixedly connected to the top of the cylindrical frame. Several teeth are fixedly connected to the inner side of the top of the teeth. The side of the teeth closest to meshing wheel 1 meshes with meshing wheel 2, and the side of meshing wheel 2, away from the teeth, meshes with meshing wheel 1. The top of meshing wheel 2 is rotatably connected to a suspension rod, the top of which is fixedly connected to the bottom of the top plate. By connecting meshing wheel 1 and the teeth in series via meshing wheel 2, rotation of meshing wheel 1 drives the funnel trough in the opposite direction, thereby achieving better grinding and spreading effects.

[0017] Compared with the prior art, the present invention has the following beneficial effects: Through low-temperature nitrogen pre-burning and high-temperature oxidation calcination, the low-temperature nitrogen pre-burning is used to decompose the organic matter by slowly heating up to avoid the gas shock caused by rapid thermal decomposition and the collapse of the structure, and then the high-temperature calcination is used to make the The crystals grow completely, which reduces the surface defects. Low temperature pre-sintering decomposes organic matter by slowly increasing the temperature, reducing the gas release rate by 60-70%, effectively reducing the gas impact caused by rapid thermal decomposition, thereby maintaining The integrity of the porous skeleton of the precursor. Experiments have shown that the porosity retention rate of the material after pre-sintering is more than 90%, and the pre-sintering process removes the residual organic matter in the precursor, which can reduce the carbon content from 2-5wt% before pre-sintering to <0.3wt%, thereby significantly improving the purity of the material. And high-temperature calcination at 600-800℃ can promote Grain growth, the grain size increases from 5-10nm after pre-sintering to 20-50nm, and the crystallinity increases from 45% to more than 85%. Therefore, by adjusting the calcination temperature, the controllable transformation from anatase phase to rutile phase can be achieved. The specific surface area reaches 120m² / g of the crucible body, and the photocatalytic efficiency is increased by 50%; the electronic conductivity is increased from / cm increased to / cm, and the cycle stability meets the requirement of 200 charge and discharge capacity retention rate>80%. Low temperature pre-sintering avoids structural damage, and high temperature calcination optimizes crystal performance, significantly improving Its high purity, crystallinity and stability make it both highly active and long-lasting, providing key material support for energy, environmental protection and other fields.

[0018] Through the composite ligand + staged hydrolysis, an efficient and controllable reaction of the titanium source can be achieved, thereby reducing the generation of impurities. The composite ligand forms a stable complex with the titanium ion through multi-dentate coordination, shielding its non-specific reaction with impurity ions in the solution. The ligand field effect changes the electron cloud distribution of the titanium ion and reduces its hydrolysis tendency. The surface of the particles can form a physical barrier, which can slow down the aggregation of particles through steric hindrance and reduce the adsorption of impurities. The reaction process is optimized by staged hydrolysis, and the impurity generation window is separated. The hydrolysis process is divided into three stages: crystal nucleation, growth precipitation, and coagulation. The first stage is eliminated by adding crystal seeds, so that the reaction directly enters the crystal nucleus growth stage, improves the uniformity of particle size, and reduces the co-precipitation of impurities caused by excessive local supersaturation. Under low-temperature hydrothermal conditions, the controllable synthesis of titanium dioxide crystals can be achieved by controlling the temperature, pH, and surfactant types. After the nucleation stage, the pH is adjusted to acidic, and the reaction is carried out using Dissolve unreacted impurity metal complexes and selectively remove them by water washing. The reduction of impurity content directly improves product purity and avoids subsequent complex purification steps. The reduction of impurities also enhances Material functional properties.

[0019] By modifying the surface of lithium phosphate, the interfacial impedance between the electrolyte and the electrode can be significantly reduced, and the coating layer can inhibit The lattice expands, the volume change after cycling is less than 4%, and the capacity attenuation rate is reduced by 60%. Moreover, the structure is stable at a high temperature of 600℃, without phase change or decomposition, and the safety is significantly improved. The reduction of interface impedance will improve the charge and discharge efficiency. The lithium phosphate coating is A uniform protective layer will form on the particle surface, thereby improving the wettability of the electrode and electrolyte and reducing the interface contact resistance. In addition, the reduction of interface impedance will reduce the internal resistance of the battery, thereby improving the charge and discharge efficiency. The expansion suppression of the lattice will enhance the cycle stability. exist The volume expansion of about 10% is likely to occur during the deintercalation process, leading to particle pulverization. The coating layer reduces the volume change rate to <4% through the physical confinement effect, significantly improving the cycle life. The reduction in capacity attenuation will extend the battery life. The coating layer inhibits the electrolyte from Direct contact reduces the loss of active substances caused by side reactions. The high-temperature structure can significantly improve stability and safety, thereby broadening application scenarios.

[0020] The meshing wheel 1, the threaded grinding block, the cylindrical frame, the meshing teeth and the meshing wheel 2 are driven by a rotating motor to rotate the meshing wheel 1, so that the meshing wheel 1 and the meshing teeth are engaged with the meshing wheel 2, which causes the meshing wheel 1 and the meshing teeth to rotate in the opposite direction. Then the meshing wheel 1 drives the threaded grinding block to rotate, thereby grinding the dry gel powder. The reverse rotation between the cylindrical frame and the threaded grinding block can achieve the effect of grinding the crystal particles in the dry gel powder. Then, the powder is evenly sprinkled into the crucible body through the reverse rotation of the cylindrical frame, thereby preventing the dry gel powder from agglomerating in the crucible body and ensuring that the dry gel powder is evenly spread inside the crucible body. The agglomerated powder will accumulate heat due to local accumulation, and the temperature difference can reach more than 50°C, while the unagglomerated powder is evenly spread to control the temperature difference within ±5°C. Moreover, the dry gel pre-sintering releases 、 Evenly spreading the dry gel powder within the crucible allows for smooth gas escape channels and reduces porosity to 8%. Agglomerated powder, on the other hand, experiences a gas-tightening effect, increasing its porosity to 15%, creating closed pores and reducing material density. Agglomerated areas are prone to the formation of impurities due to uneven heating, and avoiding agglomeration can prevent this. Evenly spreading the dry gel powder within the crucible ensures adequate contact between particles, ensuring a uniform sintering driving force during combustion in a tubular furnace. Unagglomerated powder can be directly pressed into shape, eliminating the need for ball milling. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 It is a flow chart of the steps of the present invention.

[0023] Figure 2 It is a schematic diagram of the three-dimensional structure of the device for uniformly spreading low-temperature nitrogen before pre-firing in the present invention.

[0024] Figure 3 It is a schematic diagram of the three-dimensional structure of the powder inlet trough and the fixing block of the top plate in the present invention.

[0025] Figure 4 It is a schematic diagram of the three-dimensional structure of the cylindrical frame, powder outlet and funnel trough in the present invention.

[0026] Figure 5 For the present invention Figure 4 Schematic diagram of the three-dimensional structure from another angle.

[0027] Figure 6It is a schematic diagram of the three-dimensional structure of the funnel groove and the teeth in the present invention.

[0028] Figure 7 It is a schematic diagram of the three-dimensional structure of the rotating motor, meshing wheel 1 and thread grinding block in the present invention.

[0029] Figure 8 It is a schematic diagram of the cross-sectional three-dimensional structure of the cylindrical frame, funnel groove and teeth in the present invention.

[0030] Figure 9 For the present invention Figure 8 Schematic diagram of the enlarged three-dimensional structure at point A in the middle.

[0031] In the figure: 100, crucible body; 201, top plate; 202, powder inlet trough; 203, fixing rod; 204, clamping block; 205, rotating motor; 206, conical block; 207, meshing wheel 1; 208, connecting rod; 209, threaded grinding block; 210, rotating disk; 211, cylindrical frame; 212, powder outlet; 213, funnel trough; 214, meshing teeth; 215, meshing wheel 2; 216, hanging rod. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] A method for preparing titanium dioxide for high ion conductivity battery electrolyte, such as Figure 1 As shown, the following steps are included: S1, raw material mixing and esterification reaction: titanic acid powder, excess n-butanol and a small amount of concentrated sulfuric acid are added to a three-necked flask.

[0034] S2, reflux reaction and dehydration reaction: Assemble a water separator and a condenser, heat the oil bath to 120-140°C, and maintain the reflux state for 6-12 hours.

[0035] The molar ratio of excess n-butanol is 1:4-6, and concentrated sulfuric acid accounts for 1-3% of the total weight. Concentrated sulfuric acid acts as a catalyst to promote the esterification reaction. Mechanical stirring is used to ensure thorough contact between the titanic acid powder, excess n-butanol, and a small amount of concentrated sulfuric acid. A water separator is used to separate the water generated during the reaction. Heating is stopped when the water level in the separator stabilizes, which takes approximately 4-6 hours. The water separator ensures the completeness of the esterification reaction. n-Butanol and water form an azeotrope at 93°C. A molar ratio of 1:4-6 for excess n-butanol significantly reduces the water activity of the system, shifting the esterification equilibrium toward the product. High concentrations of n-butanol increase the frequency of molecular collisions between reactants, increasing the reaction rate by approximately 40%. The water separator removes over 85% of the water within 4-6 hours, maintaining a low water activity in the reaction system. The water level changes in the water separator allow for real-time monitoring of the reaction progress, facilitating precise control of the reaction endpoint. Through the synergistic effect of excess n-butanol, concentrated sulfuric acid catalysis, mechanical stirring, water separator dehydration and oil bath temperature control, the esterification efficiency, product purity and economy are significantly improved.

[0036] S3, neutralize the acidity and separate the liquid and liquid layers: wait for the reaction liquid to cool to room temperature, slowly add dilute NaOH solution or solution.

[0037] S4, double distillation purification: recover excess n-butanol by atmospheric distillation, switch to reduced pressure distillation, and then collect colorless and transparent tetrabutyl titanate at 180-200℃. The purity of the purified product is ≥99%.

[0038] Dilute NaOH solution or The solution needs to be added dropwise until the pH value is 7, dilute NaOH solution or The solution is used to neutralize the unreacted acidic substances. The neutralized solution is transferred to a separatory funnel, which is used to stand for stratification and retain the upper organic phase. The boiling point of excess n-butanol is 117°C, and the vacuum degree of reduced pressure distillation is 0.09 MPa. By adding dilute NaOH or Neutralizing the solution to a pH of 7 prevents saponification of the product due to excess alkali. The neutralization reaction rate exceeds 95%, ensuring complete removal of unreacted acidic substances and preventing acid-catalyzed decomposition during subsequent distillation. Under a vacuum of 0.09 MPa, the boiling point of tetrabutyl titanate drops to 180-200°C, avoiding thermal decomposition caused by high temperatures and increasing product purity from 92% to 99%. Through the synergistic effects of acid neutralization, liquid-liquid separation, atmospheric distillation to recover n-butanol, and vacuum distillation to purify the product, product purity, recovery efficiency, and process safety are significantly improved, making it suitable for the industrial production of high-purity tetrabutyl titanate.

[0039] S5, ultrasound-assisted dispersion: tetrabutyl titanate and ethanolamine were dissolved in anhydrous ethanol.

[0040] S6, sol-gel conversion: in a 50-70°C water bath, slowly add aqueous acetic acid solution dropwise at a rate of 2-3 mL / min.

[0041] S7, gelation and vacuum drying: The sol was sealed and allowed to stand for 24 h to complete gelation, obtaining a translucent wet gel.

[0042] Tetrabutyl titanate is 10 g, ethanolamine is 2 g, and anhydrous ethanol is 50 mL. Ethanolamine is used as a chelating agent to stabilize titanium ions. The pH value of the acetic acid aqueous solution is 4, and the volume ratio of acetic acid to water in the acetic acid aqueous solution is 1:5. The acetic acid aqueous solution is continuously stirred until the solution turns from turbid to clear. Continuous stirring will form a uniform Sol, vacuum drying is carried out in a vacuum freeze dryer with a pre-freeze of -50℃ and a vacuum degree of <1Pa for 48 hours. Drying is used to obtain loose porous dry gel, which is crushed and passed through a 200-mesh sieve. Compared with mechanical stirring, the mixing time is shortened from 60min to 15min, and the efficiency is increased by 75%. The viscosity of the sol is regulated by an acetic acid / water volume ratio of 1:5, and the porosity of the wet gel is increased from 60% to 75%. The synergistic effect of ultrasound-assisted dispersion, sol-gel conversion and vacuum drying is significantly improved. The specific surface area, porosity and adsorption properties of the dry gel can reduce processing costs and time, making it suitable for the efficient preparation of high-performance nanomaterials.

[0043] S8, low-temperature nitrogen pre-calcination: the dry gel powder is evenly spread in the crucible body 100, the crucible body 100 is placed in a tube furnace, high-purity nitrogen is introduced, the temperature is increased to 300-400°C at 2-5°C / min, and calcined for 2h.

[0044] S9, high temperature oxidation calcination: the intermediate product after pre-calcination and cooling is re-charged into the furnace, switched to oxygen / nitrogen mixed gas, heated to 500-600°C at 3-10°C / min, and calcined for 4 hours.

[0045] The flow rate of high-purity nitrogen is 100mL / min for the crucible body, and low-temperature nitrogen pre-burning is used to remove organic matter to form amorphous The precursor, oxygen accounts for 8% in the oxygen / nitrogen mixture, the flow rate of the oxygen / nitrogen mixture is 200mL / min, and high-temperature oxidation calcination is used to improve crystallinity. Low-temperature calcination can reduce grain growth, so that the precursor specific surface area remains at 200m² / g, the porosity is 75%, and the adsorption performance is improved by 40%. High-temperature calcination at 500-600℃ increases the grain size from 5nm to 20nm, the crystallinity from 65% to 90%, and the photocatalytic activity is increased by 60%. Thus, through a two-step calcination process, low-temperature nitrogen pre-burning removes organic matter and retains the precursor structure, and then high-temperature oxidation calcination achieves controlled crystal phase transformation and crystallinity improvement, significantly optimizing photocatalytic performance and processing efficiency.

[0046] S10, nano-sizing and interface modification: The calcined product was crushed to 101-200 nm using a supersonic jet mill.

[0047] The feed pressure of the supersonic airflow mill is 0.6MPa. The calcined product after crushing is immersed in a lithium phosphate solution with a concentration of 0.1-0.5mol / L. The immersion is used to enhance the interfacial ion transmission capacity. After the immersion, vacuum drying is performed to obtain lithium phosphate-coated Nanoparticles. Achieved by supersonic air flow pulverization The nano-scaling, combined with lithium phosphate solution impregnation and vacuum drying, significantly improves the material's ion transport performance and electrochemical stability.

[0048] In step S8, before the low-temperature nitrogen pre-calcination, the dry gel powder is evenly spread on the crucible body 100. First, the cylindrical frame 211 is placed at the center of the crucible body 100. When the entire device moves downward, the clamping block 204 will fit with the surface of the crucible body 100. Due to the arc-shaped design of the exterior of the crucible body 100, the clamping block 204 will be fixed as it moves downward. At this time, the entire crushing and grinding device will be fixed inside the crucible body 100. At this time, the crushing and grinding device is started. The rotating motor 205 then transfers the dry gel powder to the top of the funnel trough 213 through the powder inlet trough 202. When the rotating motor 205 is started, the meshing wheel 1 207 is driven to rotate. Due to the meshing of the meshing wheel 1 207 and the meshing wheel 2 215, and the meshing of the meshing wheel 215 and the meshing of the gear 214, the rotation of the meshing wheel 1 207 drives the gear 214 to rotate in the opposite direction. Since the gear 214 is fixed to the inner side of the funnel trough 213 and the bottom of the funnel trough 213 The cylindrical frame 211 is fixed so that the rotation of the meshing wheel 207 will drive the cylindrical frame 211 to rotate. Since the meshing wheel 207 and the threaded grinding block 209 are fixed by a connecting rod 208, the threaded grinding block 209 will rotate in the opposite direction of the cylindrical frame 211, thereby achieving the effect of finely grinding any lumps in the xerogel powder. When the ground xerogel powder reaches a certain diameter, it will be sprinkled out through the powder outlet 212. Since the powder outlet 212 is opened on the surface of the cylindrical frame 211, the spilled xerogel powder will be evenly dispersed into the interior of the crucible body 100, thereby preventing the xerogel powder from agglomerating in the crucible body 100 and ensuring that the xerogel powder is evenly spread inside the crucible body 100. Evenly spreading the xerogel powder inside the crucible body 100 can ensure sufficient contact between the particles, uniform sintering driving force when burning in a tubular furnace, and directly press-forming the unagglomerated powder, thereby eliminating the ball milling process.

[0049] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing titanium dioxide for high ion conductivity battery electrolyte, characterized in that: The specific steps include: S1, raw material mixing and esterification reaction: titanic acid powder, excess n-butanol and a small amount of concentrated sulfuric acid are added to a three-necked flask; S2, reflux reaction and dehydration reaction: assemble a water separator and condenser, heat the oil bath to 120-140°C, and maintain reflux for 6-12 hours; S3, neutralize the acidity and separate the liquid and liquid layers: wait for the reaction liquid to cool to room temperature, slowly add dilute NaOH solution or solution; S4, double distillation purification: recover excess n-butanol by distillation at atmospheric pressure, switch to reduced pressure distillation, and then collect colorless and transparent tetrabutyl titanate at 180-200°C. The purity of the purified product is ≥99%; S5, ultrasound-assisted dispersion: tetrabutyl titanate and ethanolamine were dissolved in anhydrous ethanol; S6, sol-gel conversion: slowly add aqueous acetic acid solution dropwise in a 50-70°C water bath at a rate of 2-3 mL / min; S7, gelation and vacuum drying: the sol was sealed and allowed to stand for 24 h to complete gelation and obtain a translucent wet gel; S8, low-temperature nitrogen pre-calcination: the dry gel powder is evenly spread in the crucible body (100), the crucible body (100) is placed in a tube furnace, high-purity nitrogen is introduced, the temperature is increased to 300-400°C at 2-5°C / min, and calcined for 2h; S9, high-temperature oxidation calcination: the intermediate product after pre-calcination and cooling is re-charged into the furnace, switched to an oxygen / nitrogen mixed gas, and heated to 500-600°C at 3-10°C / min, and calcined for 4 hours; S10, nano-sizing and interface modification: The calcined product was crushed to 101-200 nm using a supersonic jet mill.

2. The method for preparing titanium dioxide for a high ionic conductivity battery electrolyte according to claim 1, wherein: In the steps S1-S2, the molar ratio of the excess n-butanol is 1:4-6, the concentrated sulfuric acid accounts for 1-3% of the total mass, the concentrated sulfuric acid serves as a catalyst to promote the esterification reaction, the mixing is performed by mechanical stirring to fully contact the metatitanic acid powder, excess n-butanol and a small amount of concentrated sulfuric acid, the water separator is used to separate the water generated in the reaction in real time, the heating is stopped when the water volume in the water separator is stable, the time required for the water volume in the water separator to stabilize is about 4-6 hours, and the water separator is used to ensure the complete esterification reaction.

3. The method for preparing titanium dioxide for a high ionic conductivity battery electrolyte according to claim 1, wherein: In steps S3-S4, the dilute NaOH solution or The solution needs to be added dropwise until the pH value is 7. The dilute NaOH solution or NaHCO3 solution is used to neutralize the unreacted acidic substance. The neutralized solution is transferred to a separatory funnel, which is used to stand and separate the layers, retaining the upper organic phase. The boiling point of the excess n-butanol is 117°C, and the vacuum degree of the reduced pressure distillation is 0.09 MPa.

4. The method for preparing titanium dioxide for high ionic conductivity battery electrolyte according to claim 1, wherein: In steps S5-S7, the tetrabutyl titanate is 10 g, the ethanolamine is 2 g, the anhydrous ethanol is 50 mL, the ethanolamine is used as a chelating agent to stabilize titanium ions, the pH value of the acetic acid aqueous solution is 4, the volume ratio of acetic acid to water in the acetic acid aqueous solution is 1:5, and the acetic acid aqueous solution is continuously stirred until the solution turns from turbid to clear, and the continuous stirring forms a uniform The sol is vacuum dried using a vacuum freeze dryer with a pre-freezing temperature of -50°C and a vacuum degree of <1 Pa for 48 hours. The drying is used to obtain a loose porous dry gel, which is crushed and passed through a 200-mesh sieve.

5. The method for preparing titanium dioxide for battery electrolyte with high ionic conductivity according to claim 1, wherein: In steps S8-S9, the flow rate of the high-purity nitrogen is 100 mL / min, and the low-temperature nitrogen pre-burning is used to remove organic matter to form amorphous Precursor, oxygen accounts for 8% in the oxygen / nitrogen mixed gas, the flow rate of the oxygen / nitrogen mixed gas is 200 mL / min, and the high-temperature oxidation calcination is used to improve crystallinity.

6. The method for preparing titanium dioxide for battery electrolyte with high ionic conductivity according to claim 1, wherein: In step S10, the feed pressure of the supersonic airflow mill is 0.6 MPa, and the calcined product after the pulverization is immersed in a lithium phosphate solution with a concentration of 0.1-0.5 mol / L, and the immersion is used to enhance the interfacial ion transmission capacity. After the immersion, vacuum drying is performed to obtain a lithium phosphate-coated Nanoparticles.

7. The method for preparing titanium dioxide for high ionic conductivity battery electrolyte according to claim 1, wherein: Four fixing blocks (204) are provided on the outer surface of the crucible body (100), the top ends of the fixing blocks (204) are fixedly connected to fixing rods (203), the top ends of the four fixing rods (203) are fixedly connected to a top plate (201), and the bottom side of the top plate (201) is fixedly connected to a powder inlet trough (202).

8. The method for preparing titanium dioxide for high ionic conductivity battery electrolyte according to claim 7, wherein: The center of the bottom end of the top plate (201) is fixedly connected to a rotating motor (205), the bottom output end of the conical block (206) is fixedly connected to the conical block (206), the bottom end of the conical block (206) is fixedly connected to a meshing wheel (207), the bottom end of the meshing wheel (207) is fixedly connected to a connecting rod (208), the bottom end of the connecting rod (208) is fixedly connected to a threaded grinding block (209), the bottom end of the threaded grinding block (209) is fixedly connected to a rotating disk (210), the outside of the rotating disk (210) is rotatably connected to a cylindrical frame (211), and the outer surface of the cylindrical frame (211) is provided with a plurality of downwardly inclined powder outlets (212).

9. The method for preparing titanium dioxide for high ionic conductivity battery electrolyte according to claim 8, wherein: The top of the cylindrical frame (211) is fixedly connected to a funnel groove (213), the inner side of the top of the tooth (214) is fixedly connected to a plurality of teeth (214), the side of the tooth (214) close to the meshing wheel (207) is meshed with the meshing wheel (215), the side of the meshing wheel (215) away from the tooth (214) is meshed with the meshing wheel (207), the top of the meshing wheel (215) is rotatably connected to the hanging rod (216), and the top of the hanging rod (216) is fixedly connected to the bottom end of the top plate (201).

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