Device and method for preparing lithium aluminum titanium phosphate

Abstract

The application relates to a device and a preparation method of titanium aluminum lithium phosphate, which comprises, in the direction of material flow, a powder feeding unit, a hot melt homogenizing unit, a spray cooling granulation unit, a coating modification unit, a pulse activation unit and a discharge plasma pulse sintering unit connected in sequence. In the application, the raw material is directly fed in a powder state, the atom / molecule level homogeneous mixing of the powder raw material is realized under the condition of no liquid solvent through the hot melt homogenizing unit, the spherical precursor particles are obtained through spray cooling granulation, and then the coating modification, pulse activation and discharge plasma pulse sintering are continuously completed, forming a full dry method, solvent-free and continuous integrated preparation route from the solid powder raw material to the dense sintered body finished product, and the technical problems of uneven mixing of the solid powder in the existing LATP preparation process, high energy consumption of the solvent treatment of the wet slurry method, lack of continuous connection between the hot melt granulation and high temperature sintering, and single function of the existing equipment and fragmentation of the process flow are solved.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte material preparation technology, and in particular to an apparatus and method for preparing lithium titanium aluminum phosphate. Background Technology

[0002] Lithium titanium aluminum phosphate (Li 1+x Al x Ti 2-x (PO4)3, LATP) solid electrolytes are currently a research hotspot in the field of solid-state batteries due to their low cost, good chemical stability, and excellent ionic conductivity. In the preparation process of LATP, the uniformity of the mixing and dispersion of the precursor directly determines the ionic conductivity and density of the final product.

[0003] Traditional LATP preparation routes are mainly divided into two categories. The first is the conventional solid-state method: directly mixing four solid raw materials—lithium carbonate, alumina, titanium dioxide, and phosphorus pentoxide—followed by high-temperature sintering. This route suffers from poor mixing uniformity, significant lithium / phosphorus volatilization, impurities introduced during ball milling, and long sintering times (several hours to tens of hours). The second is the wet spray drying granulation route: dissolving or dispersing the raw materials in a solvent to form a slurry, then atomizing and drying to obtain a uniformly mixed precursor powder, followed by high-temperature sintering. The wet route requires a large amount of solvent, resulting in high energy consumption and long drying times, and incomplete solvent removal can affect the final product performance.

[0004] In recent years, hot melt spray granulation technology has been applied in the pharmaceutical and food industries. Its principle is to heat and melt the material in a hot melt pot and then spray it through an atomizer to cool and granulate it. It does not require the use of organic solvents, is safe and pollution-free, has a fast condensation speed and does not require drying, and is suitable for continuous production processes. For example, CN205392337U discloses a hot melt spray granulator, including a first air compressor, an air heater, a drying tower, an atomizer, a syringe pump, a material hot melt pot, a primary cyclone separator, a secondary cyclone separator, and an outlet filter. The atomizer is located at the top of the drying tower. The first air compressor and the air heater are connected via pipes, and the air heater is connected to the atomizer via pipes. The material hot melt pot is connected to the syringe pump via pipes, and a stirring paddle is installed inside the material hot melt pot. The syringe pump is connected to the atomizer via pipes. The primary cyclone separator is connected to the bottom of the drying tower via pipes, and a first collection bottle is connected to it at the bottom. The secondary cyclone separator is connected to the primary cyclone separator via pipes, and a second collection bottle is connected to it at the bottom. The outlet filter is connected to the secondary cyclone separator via pipes. This hot melt spray granulator can produce granules through hot melt spraying and conventional spray drying. However, these hot melt spray granulation equipment are mainly for microcapsule granulation of low-melting-point organic materials (such as oils or polymers). Their hot melt temperature is usually no more than 200~300℃, and they do not have the ability to perform high-temperature hot melt homogenization of LATP multi-component inorganic raw materials (usually requiring P2O5 to melt at about 340℃, Li2CO3 to melt and decompose at about 723℃, and the overall mixture to undergo high-temperature homogenization treatment at 850~950℃ or higher). Furthermore, they lack deep integration with subsequent processes.

[0005] In existing patents, although the combination of spray drying and high-temperature treatment has been disclosed, all of them use wet slurry as the feed form; although hot melt spray granulation equipment has been disclosed, it is mainly used for low melting point organic materials and does not involve inorganic solid electrolyte materials.

[0006] Therefore, solving the fundamental problems in the LATP preparation process, such as uneven mixing, elemental segregation, process discontinuity, and poor batch stability, has significant engineering value and commercial significance. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides an apparatus and method for preparing lithium titanium aluminum phosphate. In this invention, the raw material is directly fed in powder form. The powder raw material is homogenized at the atomic / molecular level through a hot-melt homogenization unit under conditions without liquid solvent. Then, spherical precursor particles are obtained through a spray cooling granulation unit. Subsequently, coating modification, pulse activation, and discharge plasma pulse sintering are continuously completed, forming a completely dry, solvent-free, and continuous integrated preparation route from solid powder raw material to dense sintered finished product. This solves the technical problems in existing LATP preparation processes, such as uneven mixing of solid powder, high energy consumption of solvent treatment in wet slurry methods, lack of continuous connection between hot-melt granulation and high-temperature sintering, and the single function and fragmented process flow of existing equipment.

[0008] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides an apparatus for preparing lithium titanium aluminum phosphate, wherein, along the material flow direction, the apparatus comprises, in sequence, a powder feeding unit, a hot melting homogenization unit, a spray cooling granulation unit, a coating modification unit, a pulse activation unit, and a discharge plasma pulse sintering unit.

[0009] In the preparation of lithium titanium aluminum phosphate, this invention employs direct feeding of solid powder, achieving atomic / molecular-level homogeneous mixing of the powder raw materials through high-temperature hot melting. This fundamentally solves the component segregation problem caused by uneven mixing in solid-phase methods. Spherical precursor particles are then obtained through a spray cooling granulation unit. These spherical precursor particles exhibit good sphericity, adjustable particle size distribution, and smooth surfaces, possessing excellent flowability and bulk density. This is beneficial for the uniformity of subsequent coating and sintering processes. Compared to hollow or broken particles obtained by wet spray drying, the hot melting combined with spray cooling granulation... The resulting spherical particles are denser and stronger. This invention integrates the entire process, from powder distribution to hot-melt homogenization, spray cooling granulation, coating modification, pulse activation to discharge plasma pulse sintering, into a single device. One-click process control is achieved through the control unit, eliminating the need for material transfer between different devices and avoiding the risks of moisture absorption, oxidation, and contamination of intermediate products. This greatly improves production efficiency and batch stability. Furthermore, the entire process does not use any organic solvents or water, consumes no energy for solvent removal, and generates no waste. This achieves a completely dry and green production method for LATP preparation.

[0010] As a preferred embodiment of the present invention, the powder feeding unit includes at least four powder feeding devices.

[0011] In this invention, lithium aluminum titanium phosphate is prepared using lithium carbonate, aluminum oxide, titanium dioxide and phosphorus pentoxide as raw materials. At this time, the four raw materials need to be placed into four powder feeding devices respectively.

[0012] Preferably, the bottom of the powder feeding device is provided with a loss-in-weight metering feeder.

[0013] Preferably, the device further includes a mixing guide trough connected to the loss-in-weight metering feeder.

[0014] Preferably, the mixing guide channel includes a channel body and intermittent turbulence baffles disposed on the inner wall of the channel body.

[0015] Preferably, the sidewalls of the tank are inclined along the axial direction of the mixing guide channel.

[0016] Preferably, the angle between the sidewall of the tank and the axis of the mixing guide channel is 5 to 15°, for example, it can be 5°, 8°, 10°, 12° or 15°, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0017] In this invention, due to the inclined sidewall of the mixing guide channel and the intermittent turbulence baffle on the inner sidewall, the powder in the mixing guide channel undergoes multiple tumbling and impacts during the gravity-driven descent, thus completing the dry premixing.

[0018] As a preferred embodiment of the present invention, the hot melting homogenization unit includes a melting crucible.

[0019] Preferably, the material of the melting crucible includes any one or a combination of at least two of platinum, corundum, or boron nitride, wherein typical but non-limiting combinations include: a combination of platinum and corundum, a combination of platinum and boron nitride, a combination of corundum and boron nitride, and a combination of platinum, corundum, and boron nitride.

[0020] Preferably, the hot melting homogenization unit further includes a first heating element covered on the outer wall of the melting crucible, a stirring device disposed inside the melting crucible, and a flow control valve disposed at the bottom outlet of the melting crucible.

[0021] In this invention, the first heating element on the outer wall of the melting crucible can precisely control the temperature inside the crucible within a preset melting temperature range, allowing the temperature inside the melting crucible to vary between 25 and 1200°C. The rotation speed of the stirring device inside the melting crucible can vary between 0 and 200 rpm, and continuous stirring is performed during the hot melting process to promote the diffusion and homogenization of each component in the liquid state.

[0022] Preferably, the melting crucible is conical or cylindrical in shape.

[0023] Preferably, the material of the stirring device includes high-temperature resistant metals and / or ceramics.

[0024] Preferably, the impeller of the stirring device includes any one of anchor impeller, paddle impeller or spiral impeller.

[0025] Preferably, the hot melting homogenization unit further includes a monitoring device disposed inside the melting crucible.

[0026] Preferably, the hot-melting homogenization unit includes at least two monitoring devices.

[0027] Preferably, different monitoring devices are installed at different depths in the smelting crucible.

[0028] The monitoring device in this invention is a melt composition homogeneity monitoring device, which includes at least two thermocouples and a melt sampling port set at different depths inside the crucible, so as to monitor the melt temperature distribution and sample the composition homogeneity in real time.

[0029] As a preferred technical solution of the present invention, the spray cooling granulation unit includes a melt conveying pipeline, a melt pump, an atomizing device, a spray drying device, and a powder collecting device connected in sequence.

[0030] Preferably, the outer side of the melt delivery pipeline is sequentially covered with a resistance heating strip and a heat insulation layer.

[0031] In this invention, the melt delivery pipeline is heated to prevent the melt from solidifying and blocking the pipeline due to a drop in temperature during delivery.

[0032] Preferably, a pressure sensor and a temperature sensor are installed on the melt delivery pipeline.

[0033] Preferably, the melt pump includes either a gear pump or a screw pump.

[0034] The melt pump in this invention is used to deliver high-temperature melt to the atomizer at a stable flow rate and pressure.

[0035] Preferably, the flow rate of the melt pump is 0.5~50 kg / h, for example, it can be 0.5 kg / h, 2 kg / h, 10 kg / h, 20 kg / h or 50 kg / h, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0036] Preferably, the outlet pressure of the melt pump is 0.5~10MPa, for example, it can be 0.5MPa, 1MPa, 2MPa, 5MPa or 10MPa, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0037] Preferably, the atomizing device includes any one of a centrifugal atomizer, a pressure atomizer, or a dual-fluid atomizer.

[0038] In this invention, the atomizing disc or nozzle of the atomizing device is made of a high-temperature resistant and corrosion-resistant material (such as any one or a combination of at least two of silicon carbide, zirconium oxide ceramic or platinum-rhodium alloy) to withstand a melt temperature of 800~1100℃.

[0039] Preferably, the rotational speed of the centrifugal atomizer is 5000~30000 r / min, for example, it can be 5000 r / min, 10000 r / min, 15000 r / min, 20000 r / min or 30000 r / min, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0040] Preferably, the working pressure of the pressure atomizer is 2~20MPa, for example, it can be 2MPa, 5MPa, 10MPa, 15MPa or 20MPa, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0041] Preferably, the atomizing auxiliary gas in the dual-fluid atomizer is an inert gas.

[0042] Preferably, the inert gas includes nitrogen and / or argon.

[0043] Preferably, the temperature of the inert gas in the dual-fluid atomizer is 200~500℃, for example, it can be 200℃, 250℃, 300℃, 400℃ or 500℃, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0044] Preferably, the pressure of the inert gas in the dual-fluid atomizer is 0.2~1MPa, for example, it can be 0.2MPa, 0.4MPa, 0.6MPa, 0.8MPa or 1MPa, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0045] Preferably, the tower structure of the spray drying device is a vertical cylindrical shape.

[0046] Preferably, the height-to-diameter ratio of the spray drying device is (3~8):1, for example, it can be 3:1, 4:1, 5:1, 6:1, 7:1 or 8:1, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0047] Preferably, a cooling gas distributor is provided at the top of the spray drying device.

[0048] It should be noted that in this invention, the cooling gas is selected from nitrogen and / or argon. After being refrigerated or cooled to 0~80°C, the gas is introduced into the spray drying device and comes into contact with the high-temperature molten droplets with a diameter of 20~200μm after atomization in a co-current or counter-current manner, so that the molten droplets are rapidly cooled and solidified within a few seconds to tens of seconds to form spherical solid particles. At the same time, the inner wall of the spray drying device is provided with an anti-stick coating (such as polytetrafluoroethylene or ceramic coating) to reduce particle adhesion to the wall.

[0049] Preferably, the powder collecting device includes a conical collecting hopper and a first feeding valve connected in sequence with the spray drying device.

[0050] Preferably, the spray drying device includes an exhaust gas outlet.

[0051] Preferably, the powder collection device further includes a separation device and a dust removal device connected in sequence to the exhaust gas outlet of the spray drying device.

[0052] Preferably, the separation device includes a cyclone separator.

[0053] Preferably, the dust removal device includes a bag filter.

[0054] In this invention, the bottom collection port of the cyclone separator is connected to the lower part of the spray drying device through a return pipe to achieve the reflux collection of fine powder. The collected spherical precursor powder enters the downstream coating and modification unit through the first discharge valve.

[0055] As a preferred technical solution of the present invention, the coating modification unit includes a conical barrel, a second heating element covering the outer wall of the conical barrel, and a central rotating shaft disposed inside the conical barrel.

[0056] The second heating element of this invention has a built-in resistance heating element and a heat insulation layer, which can achieve controllable heating from 25 to 1000°C.

[0057] Preferably, the blade is inclinedly arranged on the central rotating shaft along the axial direction of the central rotating shaft.

[0058] Preferably, at least three layers of blades are provided on the central rotating shaft along its axial direction. For example, there may be three, four, or five layers, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0059] Preferably, the angle between the blade and the axis of the central rotating shaft is 30~60°, for example, it can be 30°, 35°, 40°, 50° or 60°, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0060] Preferably, the gap between the outer edge of the blade and the inner wall of the conical barrel is 2 to 5 mm, for example, it can be 2 mm, 2.5 mm, 3 mm, 4 mm or 5 mm, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0061] Preferably, the coating modification unit further includes a second discharge valve disposed at the bottom of the conical barrel.

[0062] The second feeding valve in this invention is used to introduce the coated and modified powder material into the pulse activation unit.

[0063] As a preferred embodiment of the present invention, the pulse activation unit includes an insulating cavity, a first electrode and a second electrode disposed at both ends of the insulating cavity, a discharge grid plate disposed inside the insulating cavity, and a programmable pulse power supply connected to the first electrode and the second electrode respectively.

[0064] Preferably, the insulating cavity is provided with 4 to 8 sets of staggered discharge grids, for example, 4, 5, 6, 7 or 8 sets, but not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0065] Preferably, the gap between adjacent discharge grid plates inside the insulating cavity is 0.5~3mm, for example, it can be 0.5mm, 1mm, 1.5mm, 2mm or 3mm, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0066] Preferably, the staggered discharge grids are alternately connected to the first electrode and the second electrode.

[0067] In this invention, the material passes through the gaps between the staggered discharge grids in each layer under the action of gravity, undergoes multiple pulse activation treatments, and high-energy active sites are generated on the surface of the material and atomic-level interdiffusion occurs.

[0068] Preferably, the pulse activation unit further includes a third heating element covering the outer wall of the insulating cavity.

[0069] The third heating element in this invention can maintain the temperature inside the insulating cavity at 150~400℃.

[0070] Preferably, the discharge plasma pulse sintering unit includes a vacuum chamber and a first copper electrode, an upper pressure head, a graphite sintering mold, a lower pressure head, and a second copper electrode connected sequentially inside the vacuum chamber.

[0071] Preferably, the discharge plasma pulse sintering unit further includes a DC pulse power supply connected to the first copper electrode and the second copper electrode.

[0072] Preferably, the discharge plasma pulse sintering unit further includes a vacuum pump connected to the vacuum chamber.

[0073] Preferably, the discharge plasma pulse sintering unit further includes a hydraulic pressing system connected to the upper pressure head and the lower pressure head respectively.

[0074] The hydraulic pressing system in this invention can provide axial pressing pressure of 0~200MPa for the upper and lower pressing heads respectively.

[0075] Preferably, the hot-melting homogenization unit is connected to the outlet of the mixing guide channel via a sealed pipeline.

[0076] Preferably, the spray cooling granulation unit is connected to the flow control valve via a closed pipeline.

[0077] Preferably, the coating modification unit is connected to the first feeding valve through a sealed pipeline.

[0078] Preferably, the pulse activation unit is connected to the second feeding valve through a sealed pipeline.

[0079] It should be noted that when the temperature inside the spray drying device drops to 180~250℃, the first feeding valve is automatically opened, allowing the spherical precursor particles to fall into the coating modification unit which has been preheated to 300~450℃. The synergy between the temperatures of each reaction unit saves energy consumption for heating and shortens the processing time. The coated and modified powder enters the insulating cavity of the pulse activation unit (preheated to 150~400℃) directly through the second feeding valve, keeping the powder surface in a thermally activated state.

[0080] It should be noted that, in order to ensure that the entire process from hot-melt homogenization to spray cooling granulation, and then to subsequent coating, activation, and sintering is carried out in an oxygen-free environment, the various units of the device are connected by sealed pipelines, and an integrated inert gas protection system is provided throughout the entire device. The protective atmosphere system includes: an inert gas input pipeline and flow control valve connected to the hot-melt homogenization unit; a preheating inert gas pipeline connected to the atomizer of the spray cooling granulation unit; a cooling inert gas input pipeline connected to the spray cooling granulation unit; and an airtightness detection device and a micro-positive pressure maintenance system installed between each unit to ensure that oxygen and moisture are isolated from the entire process from the powder entering the hot-melt unit to the final sintered product.

[0081] Preferably, the device further includes a control unit, which is connected to the powder feeding unit, the hot melt homogenization unit, the spray cooling granulation unit, the coating modification unit, the pulse activation unit, and the discharge plasma pulse sintering unit.

[0082] The control unit includes a programmable logic controller (PLC) and a touch screen display. The control unit is connected to the loss-in-weight metering feeder of the powder feeding unit, the first heating element, stirring device, and monitoring device of the hot melt homogenization unit, the melt pump, atomizing device, pressure and temperature sensors on the melt delivery pipeline of the spray cooling granulation unit, the drive motor, second heating element, and temperature sensor of the coating modification unit, the programmable pulse power supply and temperature sensor of the pulse activation unit, the hydraulic pressing system and vacuum pump of the discharge plasma pulse sintering unit, and the gas flow control valve and airtightness detection device of the protective atmosphere system. The control unit has a pre-set control program for the entire process flow, including the powder feeding unit, hot melt homogenization unit, spray cooling granulation unit, coating modification unit, pulse activation unit, and discharge plasma pulse sintering unit, and can automatically control the coordinated operation of each unit according to the set timing sequence. Furthermore, when the control unit is connected to the loss-in-weight metering feeder, the control unit adjusts the rotation speed of each loss-in-weight metering feeder in real time according to the preset stoichiometric ratio, so that the four powders fall into the mixing guide tank in a precise ratio and achieve preliminary mixing.

[0083] The device provided by this invention adopts a modular design, with each unit connected via standardized flange interfaces, allowing for disassembly and replacement as needed. By changing the crucible capacity, atomizer specifications, or graphite sintering molds, it can be flexibly expanded from small-batch laboratory preparation (50g per batch) to pilot-scale amplification (100g to several kilograms per batch) and even industrial mass production (10-100kg per batch), exhibiting excellent industrial-scale scalability. Furthermore, this invention has expanded the application value of high-temperature melt direct atomization granulation methods in the field of inorganic non-metallic materials. The entire process of this invention is carried out in an inert gas atmosphere, making it suitable for the large-scale industrial production of oxygen-sensitive inorganic solid electrolyte materials.

[0084] Secondly, the present invention provides a method for preparing lithium titanium aluminum phosphate, wherein the preparation method is carried out using the apparatus for preparing lithium titanium aluminum phosphate described in the first aspect.

[0085] This invention prepares lithium titanium aluminum phosphate using an apparatus that produces lithium titanium aluminum phosphate. The raw material is fed directly in powder form, and then the powder raw material is homogenized at the atomic / molecular level through hot melting and homogenization under conditions without liquid solvent. Spherical precursor particles are then obtained by spray cooling granulation, and then coating modification, pulse activation and discharge plasma pulse sintering are continuously completed to form a completely dry, solvent-free, continuous integrated preparation route from solid powder raw material to dense sintered finished product.

[0086] As a preferred technical solution of the present invention, the preparation method includes: The raw material mixture is subjected to hot melting homogenization treatment, spray cooling granulation treatment, coating modification treatment, pulse activation treatment and discharge plasma pulse sintering treatment in sequence to obtain the lithium titanium aluminum phosphate.

[0087] As a preferred technical solution of the present invention, the preparation of the raw material mixture includes: first mixing lithium carbonate, aluminum oxide, titanium dioxide and phosphorus pentoxide to obtain the raw material mixture.

[0088] Preferably, the molar ratio of lithium carbonate, alumina, titanium dioxide, and phosphorus pentoxide in the raw material mixture is (0.8~1.2):(0.15~0.35):(1.5~1.9):1, for example, it can be 0.8:0.15:1.9:1, 0.9:0.18:1.7:1, 1.0:0.21:1.75:1, 1.1:0.27:1.8:1 or 1.1:0.3:1.8:1, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0089] Preferably, the hot-melt homogenization treatment is carried out under the first stirring.

[0090] The present invention performs hot melting homogenization treatment under stirring to promote the diffusion and homogenization of the components of the melt.

[0091] Preferably, the rotation speed of the first stirring is 50~150 rpm, for example, it can be 50 rpm, 70 rpm, 100 rpm, 120 rpm or 150 rpm, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0092] Preferably, the hot melt homogenization process includes a first hot melt homogenization process, a second hot melt homogenization process, and a third hot melt homogenization process performed sequentially.

[0093] Preferably, the temperatures of the first hot melt homogenization treatment, the second hot melt homogenization treatment, and the third hot melt homogenization treatment are increased sequentially.

[0094] In this invention, a three-stage hot-melting homogenization process with progressively increasing temperatures is performed to melt P2O5, Li2CO3, and other raw materials in sequence, resulting in a more uniform mixture of the molten materials.

[0095] Preferably, the temperature of the second hot-melt homogenization treatment is 200-410°C higher than the temperature of the first hot-melt homogenization treatment. For example, it can be 200°C, 250°C, 300°C, 350°C or 410°C, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0096] Preferably, the temperature of the third hot-melt homogenization treatment is 100-500°C higher than the temperature of the second hot-melt homogenization treatment. For example, it can be 100°C, 200°C, 300°C, 400°C or 500°C, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0097] Preferably, the temperature of the first hot-melt homogenization treatment is 340~400℃, for example, it can be 340℃, 350℃, 360℃, 380℃ or 400℃, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0098] In the first hot-melt homogenization process of the present invention, the low-melting-point P2O5 melts first to form a liquid phase and initially wets and coats other solid particles.

[0099] Preferably, the holding time for the first heat-melting homogenization treatment is 10 to 30 minutes, for example, it can be 10 minutes, 15 minutes, 20 minutes, 25 minutes or 30 minutes, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0100] Preferably, the temperature of the second hot-melt homogenization treatment is 600~750℃, for example, it can be 600℃, 620℃, 650℃, 700℃ or 750℃, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0101] The second hot-melting homogenization treatment of the present invention causes Li2CO3 to decompose in the molten state and react with other components in the liquid phase to generate an intermediate phase.

[0102] Preferably, the holding time for the second heat-melting homogenization treatment is 20 to 40 minutes, for example, it can be 20 minutes, 25 minutes, 30 minutes, 35 minutes or 40 minutes, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0103] Preferably, the temperature of the third hot-melt homogenization treatment is 850~1100℃, for example, it can be 850℃, 900℃, 950℃, 1000℃ or 1100℃, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0104] The third hot-melting homogenization process of the present invention completely melts all raw materials to form a uniform LATP matrix melt.

[0105] Preferably, the holding time for the third heat-melting homogenization treatment is 30 to 90 minutes, for example, it can be 30 minutes, 40 minutes, 50 minutes, 70 minutes or 90 minutes, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0106] Preferably, the temperature of the cooling gas used in the spray cooling granulation process is 0~80℃, for example, it can be 0℃, 10℃, 20℃, 40℃, 60℃ or 80℃, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0107] Preferably, the spray cooling granulation process takes 1 to 10 minutes, for example, 1 minute, 2 minutes, 5 minutes, 7 minutes or 10 minutes, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0108] Preferably, the precursor powder is obtained after the spray cooling granulation treatment.

[0109] Preferably, the average particle size D50 of the precursor powder is 50~100μm, for example, it can be 50μm, 60μm, 70μm, 80μm, 90μm or 100μm, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0110] As a preferred technical solution of the present invention, the temperature of the coating modification treatment is 300~450℃, for example, it can be 300℃, 350℃, 400℃ or 450℃, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0111] Preferably, the coating modification treatment is carried out under a second stirring.

[0112] Preferably, the second stirring speed is 1000~3000 rpm, for example, it can be 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm or 3000 rpm, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0113] Preferably, the second stirring time is 30 to 120 minutes, for example, 30 minutes, 60 minutes, 80 minutes, 100 minutes or 120 minutes, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0114] The present invention performs coating modification treatment under stirring, which can further melt the residual P2O5 component in the powder and uniformly coat the particle surface. At the same time, the strong shearing and extrusion action generated by the gap between the blade and the inner wall of the conical barrel is used to apply mechanical chemical activation to the powder particles, eliminate particle surface defects, and expose fresh surfaces.

[0115] Preferably, the pulse current of the pulse activation process is 500~5000A, for example, it can be 500A, 1000A, 2000A, 3000A, 4000A or 5000A, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0116] Preferably, the pulse voltage of the pulse activation treatment is 5~20V, for example, it can be 5V, 8V, 10V, 15V or 20V, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0117] Preferably, the frequency of the pulse activation process is 10~500Hz, for example, it can be 10Hz, 50Hz, 100Hz, 200Hz or 500Hz, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0118] Preferably, the temperature of the pulse activation treatment is 150~400℃, for example, it can be 150℃, 200℃, 250℃, 300℃ or 400℃, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0119] Preferably, the pulse activation treatment time is 5 to 60 minutes, for example, it can be 5 minutes, 10 minutes, 20 minutes, 40 minutes or 60 minutes, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0120] Preferably, the material in the pulse activation process accounts for 10-90% of the volume of the insulating cavity in the pulse activation unit. For example, it can be 10%, 30%, 50%, 70% or 90%, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0121] Preferably, the vacuum degree of the discharge plasma pulse sintering treatment is ≤6.7×10⁻⁶. -3 Pa, for example, could be 1×10 -3 Pa, 2×10 -3 Pa, 3×10 -3 Pa, 4×10 -3 Pa, 5×10 -3 Pa or 6.7 × 10 -3Pa, but not limited to the listed values, applies to other unlisted values ​​within the above range as well.

[0122] Preferably, the pressure of the discharge plasma pulse sintering treatment is 10~200MPa, for example, it can be 10MPa, 50MPa, 100MPa, 150MPa or 200MPa, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0123] Preferably, the pulse current of the discharge plasma pulse sintering process is 3000~30000A, for example, it can be 3000A, 5000A, 10000A, 20000A or 30000A, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0124] Preferably, the pulse voltage of the discharge plasma pulse sintering process is 3~10V, for example, it can be 3V, 4V, 6V, 8V or 10V, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0125] Preferably, the heating rate of the discharge plasma pulse sintering treatment is 100~200℃ / min, for example, it can be 100℃ / min, 120℃ / min, 140℃ / min, 160℃ / min, 180℃ / min or 200℃ / min, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0126] Preferably, the temperature of the discharge plasma pulse sintering treatment is 800~1000℃, for example, it can be 800℃, 850℃, 900℃, 950℃ or 1000℃, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0127] Preferably, the holding time for the discharge plasma pulse sintering treatment is 2 to 10 minutes, for example, 2 minutes, 4 minutes, 6 minutes, 8 minutes or 10 minutes, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0128] Preferably, the preparation method includes the following steps: (1) Lithium carbonate, aluminum oxide, titanium dioxide and phosphorus pentoxide are mixed in a molar ratio of (0.8~1.2):(0.15~0.35):(1.5~1.9):1 to obtain a raw material mixture; (2) At a speed of 50~150 rpm, the raw material mixture is subjected to a first hot melt homogenization treatment at a temperature of 340~400℃ and a holding time of 10~30 min, a second hot melt homogenization treatment at a temperature of 600~750℃ and a holding time of 20~40 min, and a third hot melt homogenization treatment at a temperature of 850~1100℃ and a holding time of 30~90 min to obtain the hot melted material; (3) Spray cooling and granulation treatment of the hot-melted material is carried out with cooling gas at a temperature of 0~80℃ for 1~10min to obtain precursor powder with an average particle size D50 of 50~100μm; (4) At a rotation speed of 1000~3000 rpm, the precursor powder is subjected to a coating modification treatment at a temperature of 300~450℃ for 30~120 min to obtain the modified material; (5) The modified material is subjected to pulse activation treatment with a pulse current of 500~5000A, a pulse voltage of 5~20V, a frequency of 10~500Hz, a temperature of 150~400℃, and a time of 5~60min to obtain activated material; wherein, the modified material accounts for 10~90% of the volume of the insulating cavity in the pulse activation unit during the pulse activation treatment; (6) When the vacuum degree is ≤6.7×10 -3 Under pressure of 10-200 MPa, pulse current of 3000-30000 A, pulse voltage of 3-10 V, temperature of 800-1000 °C, and holding time of 2-10 min, the activated material is subjected to discharge plasma pulse sintering treatment. After the discharge plasma pulse sintering treatment is completed, the pulse power supply and heating are stopped, and the pressing pressure is maintained to allow the sample to cool naturally in vacuum to 20-25 °C before demolding to obtain the lithium titanium aluminum phosphate. The heating rate of the discharge plasma pulse sintering treatment is 100-200 °C / min.

[0129] It should be noted that the apparatus in this invention can be used not only to prepare lithium titanium aluminum phosphate, but also to prepare lithium lanthanum zirconium oxide (Li7La3Zr3O). 12 LLZO), lithium aluminum germanium phosphorus oxide (Li 1.5 Al 0.5 Ge 1.5 (PO4)3, LAGP) and lithium lanthanum titanium oxide (Li3) x La 2 / 3-x TiO3 (x≈0.11), LLTO) multi-element oxide solid electrolyte or inorganic ceramic powder material, the parameters in the preparation process can be adjusted as needed by those skilled in the art.

[0130] Compared with the prior art, the present invention has at least the following beneficial effects: This invention employs direct solid powder feeding in the preparation of lithium titanium aluminum phosphate. High-temperature hot melting achieves atomic / molecular-level homogeneous mixing of the powder raw materials, fundamentally solving the component segregation problem caused by uneven mixing in solid-phase methods. Spherical precursor particles are then obtained through a spray-cooling granulation unit. These spherical precursor particles exhibit good sphericity, adjustable particle size distribution, and smooth surfaces, possessing excellent flowability and packing density. This is beneficial for the uniformity of subsequent coating and sintering processes. Compared to hollow or broken particles obtained by wet spray drying, the spherical particles obtained by hot melting combined with spray cooling granulation are denser and stronger, resulting in a final lithium titanium aluminum phosphate density exceeding 97.1% and an ionic conductivity of 6.2 × 10⁻⁶. -4 With a strength of S / cm or higher, this invention integrates the entire process—from powder distribution to hot-melt homogenization, spray cooling granulation, coating modification, pulse activation to discharge plasma pulse sintering—into a single device. One-click process control is achieved through a control unit, eliminating the need for material transfer between different devices and avoiding the risks of moisture absorption, oxidation, and contamination of intermediate products. This greatly improves production efficiency and batch stability. Furthermore, the entire process does not use any organic solvents or water, consumes no energy for solvent removal, and generates no waste, achieving a completely dry and green production method for LATP preparation. Attached Figure Description

[0131] Figure 1 This is a schematic diagram of the apparatus for preparing lithium titanium aluminum phosphate provided in Embodiment 1 of the present invention.

[0132] Figure 2 This is a schematic diagram of the powder feeding unit provided in Embodiment 1 of the present invention.

[0133] Figure 3 This is a schematic diagram of the structure of the hot melt homogenization unit provided in Embodiment 1 of the present invention.

[0134] Figure 4 This is a schematic diagram of the structure of the spray cooling granulation unit provided in Embodiment 1 of the present invention.

[0135] Figure 5 This is a schematic diagram of the structure of the coating modification unit provided in Embodiment 1 of the present invention.

[0136] Figure 6 This is a schematic diagram of the pulse activation unit provided in Embodiment 1 of the present invention.

[0137] Figure 7 This is a schematic diagram of the structure of the discharge plasma pulse sintering unit provided in Embodiment 1 of the present invention.

[0138] Among them, 1-Powder feeding unit; 11-First powder feeding device; 12-Second powder feeding device; 13-Third powder feeding device; 14-Fourth powder feeding device; 15-Loss-in-weight metering feeder; 16-Mixing guide trough; 2-Hot melting homogenization unit; 21-Melting crucible; 22-First heating element; 23-Stirring device; 24-Flow control valve; 3-Spray cooling granulation unit; 31-Mel conveying pipeline; 32-Mel pump; 33-Atomizing device; 34-Spray drying device; 35-Conical collecting hopper; 36-First discharge. 4-Valve; 5-Coating modification unit; 6-Conical barrel; 7-Second heating element; 8-Blade; 9-Second feeding valve; 10-Pulse activation unit; 11-Insulating cavity; 12-Third heating element; 13-First electrode; 14-Second electrode; 15-Discharge grid; 16-Programmable pulse power supply; 17-Discharge plasma pulse sintering unit; 18-Vacuum cavity; 19-First copper electrode; 20-Upper pressure head; 21-Graphite sintering mold; 32-Lower pressure head; 43-Second copper electrode; 54-DC pulse power supply; 65-Control unit. Detailed Implementation

[0139] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0140] Example 1 This embodiment provides an apparatus for preparing lithium titanium aluminum phosphate, such as... Figure 1 As shown, along the material flow direction, the device includes a powder feeding unit 1, a hot melt homogenization unit 2, a spray cooling granulation unit 3, a coating modification unit 4, a pulse activation unit 5, and a discharge plasma pulse sintering unit 6 connected in sequence; the device also includes a control unit 7 connected to the powder feeding unit 1, the hot melt homogenization unit 2, the spray cooling granulation unit 3, the coating modification unit 4, the pulse activation unit 5, and the discharge plasma pulse sintering unit 6 respectively.

[0141] like Figure 2 As shown, the powder feeding unit 1 includes a first powder feeding device 11, a second powder feeding device 12, a third powder feeding device 13, and a fourth powder feeding device 14; each of the four powder feeding devices is equipped with a loss-in-weight metering feeder 15 at its bottom; the device also includes a mixing guide trough 16 connected to the loss-in-weight metering feeder 15; the mixing guide trough 16 includes a trough body and intermittent turbulence baffles disposed on the inner wall of the trough body; the angle between the side wall of the trough body and the axis of the mixing guide trough 16 is 10°.

[0142] The hot-melting homogenization unit 2 is connected to the outlet of the mixing guide channel 16 via a sealed pipeline, such as... Figure 3 As shown, the hot melting homogenization unit 2 includes a melting crucible 21, a first heating element 22 covering the outer wall of the melting crucible 21, a stirring device 23 disposed inside the melting crucible 21, and a flow control valve 24 disposed at the bottom outlet of the melting crucible 21; the hot melting homogenization unit 2 also includes two monitoring devices disposed inside the melting crucible 21; the heights of the two monitoring devices from the bottom surface of the melting crucible 21 are 20mm and 80mm, respectively; The melting crucible 21 is made of platinum, is conical in shape, and has an effective volume of 2L; the stirring device 23 is made of high-temperature resistant metal (grade GH3128); and the blades of the stirring device 23 are anchor blades.

[0143] The spray cooling granulation unit 3 is connected to the flow control valve 24 via a closed pipeline; for example Figure 4 As shown, the spray cooling granulation unit 3 includes a melt conveying pipeline 31, a melt pump 32, an atomizing device 33, a spray drying device 34, and a powder collecting device connected in sequence. The melt conveying pipeline 31 is covered with a resistance heating strip and an insulation layer in sequence. A pressure sensor and a temperature sensor are installed on the melt conveying pipeline 31. The spray drying device 34 has a tower-shaped structure that is a vertical cylindrical shape, and its height-to-diameter ratio is 5:1. A cooling gas distributor is installed at the top of the spray drying device 34. The powder collecting device includes a conical collecting hopper 35 and a first discharge valve 36 connected in sequence to the spray drying device 34. The spray drying device 34 includes an exhaust gas outlet. The powder collecting device also includes a cyclone separator and a bag filter connected in sequence to the exhaust gas outlet of the spray drying device 34. The melt pump 32 is a gear pump; the flow rate of the melt pump 32 is 3 kg / h and the pump outlet pressure is 5 MPa; the atomizing device 33 is a centrifugal atomizer with a rotation speed of 15000 r / min.

[0144] The coating modification unit 4 is connected to the first feeding valve 36 via a sealed pipeline; such as Figure 5 As shown, the coating modification unit 4 includes a conical barrel 41 (effective volume of 2L), a second heating element 42 covering the outer wall of the conical barrel 41, a central rotating shaft disposed inside the conical barrel 41, and a second feeding valve 44 disposed at the bottom of the conical barrel 41; four layers of blades 43 are obliquely disposed on the central rotating shaft along the axial direction of the central rotating shaft; the angle between the blades 43 and the axis of the central rotating shaft is 45°; the gap between the outer edge of the blades 43 and the inner wall of the conical barrel 41 is 4mm.

[0145] The pulse activation unit 5 is connected to the second discharge valve 44 via a sealed pipeline; for example Figure 6As shown, the pulse activation unit 5 includes an insulating cavity 51 (effective volume of 0.5L), a third heating element 52 covering the outer wall of the insulating cavity 51, a first electrode 53 and a second electrode 54 disposed at both ends of the insulating cavity 51, six sets of staggered discharge grid plates 55 disposed inside the insulating cavity 51, and a programmable pulse power supply 56 respectively connected to the first electrode 53 and the second electrode 54; the gap between adjacent discharge grid plates 55 inside the insulating cavity 51 is 2mm; the staggered discharge grid plates 55 are alternately connected to the first electrode 53 and the second electrode 54.

[0146] like Figure 7 As shown, the discharge plasma pulse sintering unit 6 includes a vacuum chamber 61 and a first copper electrode 62, an upper pressure head 63, a graphite sintering mold 64, a lower pressure head 65, and a second copper electrode 66 connected sequentially inside the vacuum chamber 61; the discharge plasma pulse sintering unit 6 also includes a DC pulse power supply 67 connected to the first copper electrode 62 and the second copper electrode 66, a vacuum pump connected to the vacuum chamber 61, and a hydraulic pressing system connected to the upper pressure head 63 and the lower pressure head 65 respectively.

[0147] Example 2 This embodiment provides an apparatus for preparing lithium titanium aluminum phosphate. Along the material flow direction, the apparatus includes a powder feeding unit, a hot melt homogenization unit, a spray cooling granulation unit, a coating modification unit, a pulse activation unit, and a discharge plasma pulse sintering unit connected in sequence. The apparatus also includes control units connected to the powder feeding unit, the hot melt homogenization unit, the spray cooling granulation unit, the coating modification unit, the pulse activation unit, and the discharge plasma pulse sintering unit, respectively.

[0148] The powder feeding unit includes a first powder feeding device, a second powder feeding device, a third powder feeding device, and a fourth powder feeding device; each of the four powder feeding devices is equipped with a loss-in-weight metering feeder at its bottom; the device also includes a mixing guide trough connected to the loss-in-weight metering feeder; the mixing guide trough includes a trough body and intermittent turbulence baffles disposed on the inner wall of the trough body; the angle between the side wall of the trough body and the axis of the mixing guide trough is 8°.

[0149] The hot-melting homogenization unit is connected to the outlet of the mixing guide tank through a sealed pipeline. The hot-melting homogenization unit includes a melting crucible, a first heating element covering the outer wall of the melting crucible, a stirring device disposed inside the melting crucible, and a flow control valve disposed at the bottom outlet of the melting crucible. The hot-melting homogenization unit also includes two monitoring devices disposed inside the melting crucible. The heights of the two monitoring devices from the bottom surface of the melting crucible are 30 mm and 70 mm, respectively. The melting crucible is made of corundum, has a cylindrical shape, and an effective volume of 2L; the stirring device is made of ceramic (material name: alumina ceramic, grade: Al2O3-99); and the stirring device has paddle blades.

[0150] The spray cooling granulation unit is connected to the flow control valve via a closed pipeline; the spray cooling granulation unit includes a melt conveying pipeline, a melt pump, an atomizing device, a spray drying device, and a powder collecting device connected in sequence; the outer side of the melt conveying pipeline is covered with a resistance heating belt and an insulation layer in sequence; a pressure sensor and a temperature sensor are installed on the melt conveying pipeline; the tower structure of the spray drying device is a vertical cylindrical shape, and the height-to-diameter ratio of the spray drying device is 3:1; a cooling gas distributor is installed at the top of the spray drying device; the powder collecting device includes a conical collecting hopper and a first feeding valve connected in sequence to the spray drying device; the spray drying device includes an exhaust gas outlet; the powder collecting device also includes a cyclone separator and a bag filter connected in sequence to the exhaust gas outlet of the spray drying device. The melt pump is a screw pump; the flow rate of the melt pump is 10 kg / h and the pump outlet pressure is 10 MPa; the atomizing device is a pressure atomizer with a working pressure of 10 MPa.

[0151] The coating modification unit is connected to the first discharge valve through a sealed pipeline; the coating modification unit includes a conical barrel (effective volume of 2L), a second heating element covering the outer wall of the conical barrel, a central rotating shaft disposed inside the conical barrel, and a second discharge valve disposed at the bottom of the conical barrel; three layers of blades are obliquely disposed on the central rotating shaft along its axial direction; the angle between the blades and the axis of the central rotating shaft is 30°; the gap between the outer edge of the blades and the inner wall of the conical barrel is 5mm.

[0152] The pulse activation unit is connected to the second discharge valve through a sealed pipeline; the pulse activation unit includes an insulating cavity (effective volume of 0.5L), a third heating element covering the outer wall of the insulating cavity, a first electrode and a second electrode disposed at both ends of the insulating cavity, eight sets of staggered discharge grids disposed inside the insulating cavity, and a programmable pulse power supply respectively connected to the first electrode and the second electrode; the gap between adjacent discharge grids inside the insulating cavity is 0.5mm; the staggered discharge grids are alternately connected to the first electrode and the second electrode.

[0153] The discharge plasma pulse sintering unit includes a vacuum chamber and a first copper electrode, an upper pressure head, a graphite sintering mold, a lower pressure head, and a second copper electrode connected sequentially inside the vacuum chamber; the discharge plasma pulse sintering unit also includes a DC pulse power supply connected to the first copper electrode and the second copper electrode, a vacuum pump connected to the vacuum chamber, and a hydraulic pressing system connected to the upper pressure head and the lower pressure head respectively.

[0154] Example 3 This embodiment provides an apparatus for preparing lithium titanium aluminum phosphate. Along the material flow direction, the apparatus includes a powder feeding unit, a hot melt homogenization unit, a spray cooling granulation unit, a coating modification unit, a pulse activation unit, and a discharge plasma pulse sintering unit connected in sequence. The apparatus also includes control units connected to the powder feeding unit, the hot melt homogenization unit, the spray cooling granulation unit, the coating modification unit, the pulse activation unit, and the discharge plasma pulse sintering unit, respectively.

[0155] The powder feeding unit includes a first powder feeding device, a second powder feeding device, a third powder feeding device, and a fourth powder feeding device; each of the four powder feeding devices is equipped with a loss-in-weight metering feeder at its bottom; the device also includes a mixing guide trough connected to the loss-in-weight metering feeder; the mixing guide trough includes a trough body and intermittent turbulence baffles disposed on the inner wall of the trough body; the angle between the side wall of the trough body and the axis of the mixing guide trough is 12°.

[0156] The hot-melting homogenization unit is connected to the outlet of the mixing guide tank through a sealed pipeline. The hot-melting homogenization unit includes a melting crucible, a first heating element covering the outer wall of the melting crucible, a stirring device disposed inside the melting crucible, and a flow control valve disposed at the bottom outlet of the melting crucible. The hot-melting homogenization unit also includes two monitoring devices disposed inside the melting crucible. The heights of the two monitoring devices from the bottom surface of the melting crucible are 25 mm and 75 mm, respectively. The melting crucible is made of boron nitride, is cylindrical in shape, and has an effective volume of 2L; the stirring device is made of high-temperature resistant metal (material name: high-temperature resistant nickel-based alloy, grade: GH4169); and the impeller of the stirring device is a spiral impeller.

[0157] The spray cooling granulation unit is connected to the flow control valve via a closed pipeline; the spray cooling granulation unit includes a melt conveying pipeline, a melt pump, an atomizing device, a spray drying device, and a powder collecting device connected in sequence; the outer side of the melt conveying pipeline is covered with a resistance heating belt and an insulation layer in sequence; a pressure sensor and a temperature sensor are installed on the melt conveying pipeline; the tower structure of the spray drying device is a vertical cylindrical shape, and the height-to-diameter ratio of the spray drying device is 8:1; a cooling gas distributor is installed at the top of the spray drying device; the powder collecting device includes a conical collecting hopper and a first feeding valve connected in sequence to the spray drying device; the spray drying device includes an exhaust gas outlet; the powder collecting device also includes a cyclone separator and a bag filter connected in sequence to the exhaust gas outlet of the spray drying device; The melt pump is a gear pump or a screw pump; the flow rate of the melt pump is 1 kg / h and the pump outlet pressure is 0.5 MPa; the atomizing device is a two-fluid atomizer; the atomizing auxiliary gas in the two-fluid atomizer is argon gas at a temperature of 300℃ and a pressure of 0.5 MPa.

[0158] The coating modification unit is connected to the first discharge valve through a sealed pipeline; the coating modification unit includes a conical barrel (effective volume of 2L), a second heating element covering the outer wall of the conical barrel, a central rotating shaft disposed inside the conical barrel, and a second discharge valve disposed at the bottom of the conical barrel; three layers of blades are obliquely disposed on the central rotating shaft along the axial direction of the central rotating shaft; the angle between the blades and the axis of the central rotating shaft is 60°; the gap between the outer edge of the blades and the inner wall of the conical barrel is 2mm.

[0159] The pulse activation unit is connected to the second discharge valve through a sealed pipeline; the pulse activation unit includes an insulating cavity (effective volume of 0.5L), a third heating element covering the outer wall of the insulating cavity, a first electrode and a second electrode disposed at both ends of the insulating cavity, four sets of staggered discharge grids disposed inside the insulating cavity, and a programmable pulse power supply connected to the first electrode and the second electrode respectively; the gap between adjacent discharge grids inside the insulating cavity is 3mm; the staggered discharge grids are alternately connected to the first electrode and the second electrode.

[0160] The discharge plasma pulse sintering unit includes a vacuum chamber and a first copper electrode, an upper pressure head, a graphite sintering mold, a lower pressure head, and a second copper electrode connected sequentially inside the vacuum chamber; the discharge plasma pulse sintering unit also includes a DC pulse power supply connected to the first copper electrode and the second copper electrode, a vacuum pump connected to the vacuum chamber, and a hydraulic pressing system connected to the upper pressure head and the lower pressure head respectively.

[0161] Example 4 This embodiment provides an apparatus for preparing lithium titanium aluminum phosphate. The only difference from Embodiment 1 is that the apparatus does not include a mixing guide tank, but is otherwise the same as Embodiment 1.

[0162] Example 5 This embodiment provides an apparatus for preparing lithium titanium aluminum phosphate. The only difference from Embodiment 1 is that, except that the outside of the melt conveying pipeline is not covered with a resistance heating strip and a heat insulation layer, the apparatus is the same as that in Embodiment 1.

[0163] Comparative Example 1 This comparative example provides an apparatus for preparing lithium titanium aluminum phosphate. The only difference from Example 1 is that, except along the material flow direction, the apparatus includes a ball milling unit and a sintering unit connected in sequence. The ball milling unit includes a ball milling jar. All other aspects are the same as in Example 1.

[0164] Comparative Example 2 This comparative example provides an apparatus for preparing lithium titanium aluminum phosphate. The only difference from Example 1 is that, except along the material flow direction, the apparatus includes a mixing unit, a wet spray drying unit, and a sintering unit connected in sequence. Except for the mixing unit being used to mix the raw materials and solvent, the rest is the same as in Example 1.

[0165] The wet spray drying unit in this comparative example is a spray dryer commonly used in the prior art, and the sintering unit in Comparative Example 1 and Comparative Example 2 uses a box furnace commonly used in the prior art for sintering. Those skilled in the art can choose according to their needs, and no limitation is made here.

[0166] Application Example 1 This application example provides a method for preparing lithium titanium aluminum phosphate. This application example uses the apparatus provided in Example 1, and the preparation method includes the following steps: (1) 47.2g of lithium carbonate, 15.3g of aluminum oxide, 135.8g of titanium dioxide and 106.4g of phosphorus pentoxide were mixed in the first step to obtain a raw material mixture; (2) At a speed of 100 rpm, the raw material mixture is subjected to a first hot melt homogenization treatment at a temperature of 360℃ and a holding time of 15 min, a second hot melt homogenization treatment at a temperature of 700℃ and a holding time of 30 min, and a third hot melt homogenization treatment at a temperature of 950℃ and a holding time of 45 min to obtain the hot melted material. (3) The hot-melted material was spray-cooled and granulated for 3 minutes using nitrogen gas at a temperature of 25°C to obtain precursor powder with an average particle size D50 of 85 μm; (4) At a rotation speed of 2000 rpm, the precursor powder is subjected to a coating modification treatment at a temperature of 380°C for 60 min to obtain the modified material; (5) The modified material is subjected to pulse activation treatment with a pulse current of 1500A, a pulse voltage of 12V, a frequency of 100Hz, a temperature of 250℃, and a time of 15min to obtain activated material; wherein, the modified material accounts for 50% of the volume of the insulating cavity in the pulse activation unit during the pulse activation treatment; (6) At a vacuum degree of 6.7 × 10 -3 Under pressure of 50 MPa, the activated material was subjected to discharge plasma pulse sintering treatment at a pulse current of 10000 A, a pulse voltage of 5 V, a temperature of 900 °C, and a holding time of 5 min. After the discharge plasma pulse sintering treatment was completed, the pulse power supply and heating were stopped, and the sample was allowed to cool naturally to 25 °C in a vacuum while maintaining the pressing pressure before demolding to obtain the lithium aluminum titanium phosphate (Li). 1.3 Al 0.3 Ti 1.7 (PO4)3), wherein the heating rate of the discharge plasma pulse sintering treatment is 150℃ / min.

[0167] Application Example 2 This application example provides a method for preparing lithium titanium aluminum phosphate. This application example uses the apparatus provided in Example 2, and the preparation method includes the following steps: (1) 44.3g lithium carbonate, 15.3g aluminum oxide, 135.8g titanium dioxide and 106.4g phosphorus pentoxide were mixed in the first step to obtain the raw material mixture; (2) At a rotation speed of 50 rpm, the raw material mixture is subjected to a first hot melt homogenization treatment at a temperature of 340℃ and a holding time of 30 min, a second hot melt homogenization treatment at a temperature of 750℃ and a holding time of 20 min, and a third hot melt homogenization treatment at a temperature of 850℃ and a holding time of 90 min, to obtain the hot melted material. (3) The hot-melted material was spray-cooled and granulated for 5 minutes using nitrogen gas at 0℃ to obtain precursor powder with an average particle size D50 of 65μm; (4) At a rotation speed of 3000 rpm, the precursor powder is subjected to a coating modification treatment at a temperature of 450°C for 30 min to obtain the modified material; (5) The modified material is subjected to pulse activation treatment with a pulse current of 5000A, a pulse voltage of 20V, a frequency of 500Hz, a temperature of 400℃, and a time of 5min to obtain activated material; wherein, the modified material accounts for 10% of the volume of the insulating cavity in the pulse activation unit during the pulse activation treatment; (6) At a vacuum degree of 3×10 -3Under pressure of 10 MPa, the activated material was subjected to discharge plasma pulse sintering treatment at a pulse current of 3000 A, a pulse voltage of 3 V, a temperature of 800 °C, and a holding time of 10 min. After the discharge plasma pulse sintering treatment was completed, the pulse power supply and heating were stopped, and the sample was allowed to cool naturally to 20 °C in a vacuum while maintaining the pressing pressure before demolding to obtain the lithium titanium aluminum phosphate (Li). 1.3 Al 0.3 Ti 1.7 (PO4)3), wherein the heating rate of the discharge plasma pulse sintering treatment is 100℃ / min.

[0168] Application Example 3 This application example provides a method for preparing lithium titanium aluminum phosphate. This application example uses the apparatus provided in Example 3, and the preparation method includes the following steps: (1) 51.7g lithium carbonate, 25.5g aluminum oxide, 119.8g titanium dioxide and 106.4g phosphorus pentoxide were mixed in the first step to obtain the raw material mixture; (2) At a speed of 150 rpm, the raw material mixture is subjected to a first hot melt homogenization treatment at a temperature of 400℃ and a holding time of 10 min, a second hot melt homogenization treatment at a temperature of 600℃ and a holding time of 40 min, and a third hot melt homogenization treatment at a temperature of 1100℃ and a holding time of 30 min to obtain the hot melted material. (3) The hot-melted material was spray-cooled and granulated for 2 minutes using argon gas at 80°C to obtain precursor powder with an average particle size D50 of 100 μm; (4) At a rotation speed of 1000 rpm, the precursor powder is subjected to a coating modification treatment at a temperature of 300℃ for 120 min to obtain the modified material; (5) The modified material is subjected to pulse activation treatment with a pulse current of 500A, a pulse voltage of 5V, a frequency of 10Hz, a temperature of 150℃, and a time of 60min to obtain the activated material; wherein, the modified material accounts for 90% of the volume of the insulating cavity in the pulse activation unit during the pulse activation treatment; (6) At a vacuum degree of 1×10 -3 Under pressure of 200 MPa, the activated material was subjected to discharge plasma pulse sintering treatment at a pressure of 30000 A, a pulse voltage of 10 V, a temperature of 1000 °C, and a holding time of 2 min. After the discharge plasma pulse sintering treatment was completed, the pulse power supply and heating were stopped, and the sample was allowed to cool naturally to 25 °C in a vacuum while maintaining the pressing pressure before demolding to obtain the lithium aluminum titanium phosphate (Li). 1.5 Al 0.5 Ti 1.5(PO4)3), wherein the heating rate of the discharge plasma pulse sintering treatment is 200℃ / min.

[0169] Application Example 4 This application example provides a method for preparing lithium titanium aluminum phosphate. The only difference between this method and application example 1 is that the preparation method is carried out using the apparatus provided in example 4, while the rest is the same as application example 1.

[0170] Application Example 5 This application example provides a method for preparing lithium titanium aluminum phosphate. The only difference between this method and application example 1 is that the preparation method is carried out using the apparatus provided in example 5, while the rest is the same as application example 1.

[0171] Application Example 6 This application example provides a method for preparing lithium titanium aluminum phosphate. The only difference from application example 1 is that step (2) is adjusted to: at a rotation speed of 100 rpm, the raw material mixture is subjected to a first hot melt homogenization treatment at a temperature of 700°C and a holding time of 45 min and a second hot melt homogenization treatment at a temperature of 950°C and a holding time of 45 min in sequence to obtain the hot melted material. The rest is the same as application example 1.

[0172] Application Example 7 This application example provides a method for preparing lithium titanium aluminum phosphate. The only difference from application example 1 is that step (2) is adjusted to: hot melting homogenization treatment of the raw material mixture at a temperature of 950°C and a holding time of 90 min at a rotation speed of 100 rpm to obtain the hot-melted material. The rest is the same as application example 1.

[0173] Comparative Application Example 1 This comparative application example provides a method for preparing lithium titanium aluminum phosphate. The only difference between this method and application example 1 is that the preparation method uses the apparatus provided in comparative example 1, and the ball milling speed is 400 rpm and the time is 12 h, while the sintering temperature is 950 °C and the time is 8 h. All other aspects are the same as application example 1.

[0174] Comparative Application Example 2 This comparative application example provides a method for preparing lithium titanium aluminum phosphate, which differs from Application Example 1 only in that the preparation method uses the apparatus provided in Comparative Example 2, and the preparation method is adjusted as follows: (1) In deionized water, 47.2g of lithium carbonate, 15.3g of aluminum oxide, 135.8g of titanium dioxide and 106.4g of phosphorus pentoxide were mixed to obtain a raw material mixture with a solid content of 30wt%. (2) The raw material mixture is subjected to spray drying at an inlet temperature of 220°C and an outlet temperature of 100°C to obtain precursor powder; (3) The precursor powder was sintered at a temperature of 950°C for 8 hours to obtain the lithium titanium aluminum phosphate. The rest of the process was the same as in Application Example 1.

[0175] The density of lithium titanium aluminum phosphate prepared in the above application examples and comparative application examples was tested using the Archimedes displacement method. The density of lithium titanium aluminum phosphate was calculated using the formula: density (%) = measured density / theoretical density × 100%. The lithium titanium aluminum phosphate prepared in the above application examples and comparative application examples was assembled into a symmetrical battery with stainless steel sheets. The impedance spectrum of the symmetrical battery at 25°C was measured using a Bio-Logical electrochemical workstation. The ionic conductivity was calculated using the formula σ = L / (R × S), where σ is the ionic conductivity, L is the electrolyte thickness, R is the electrolyte impedance, and S is the effective contact area of ​​the electrolyte. The test results are shown in Table 1.

[0176] Table 1 The test results show that: (1) As can be seen from Application Examples 1 to 3, the equipment and method of the present invention achieves uniform mixing at the atomic / molecular level under solvent-free conditions through a six-stage synergistic process of hot melt homogenization, spray cooling granulation, coating modification, pulse activation, and discharge plasma pulse sintering. The resulting LATP solid electrolyte has a density of over 97.1% and an ionic conductivity of 6.2 × 10⁻⁶. -4 The S / cm ratio is above 0.3, and the Al content in LATP can vary between 0.3 and 0.5.

[0177] (2) As can be seen from Application Example 1 and Application Example 4, the turbulence baffle structure of the mixing guide channel in this invention is beneficial to the premixing of powder. The absence of a mixing guide channel allows the material to be mixed directly in the hot melting homogenization unit without a premixing process, resulting in a slight decrease in the density and conductivity of the prepared lithium titanium aluminum phosphate, but it is still significantly better than the traditional method.

[0178] (3) As can be seen from Application Example 1 and Application Example 5, the heating and heat preservation of the melt conveying pipeline in this invention is crucial to prevent the solidification of the high-temperature melt and ensure continuous and stable granulation. Without this measure, the sphericity of the particles will deteriorate, the performance will be reduced, and the density and conductivity of the prepared lithium titanium aluminum phosphate will decrease slightly.

[0179] (4) As can be seen from Application Example 1 and Examples 6-7, the three-step stepped heating and melting homogenization in this invention (first melting P2O5, then decomposing Li2CO3, and finally forming a homogeneous melt) can achieve more complete reaction and uniform mixing of each component than two-step or one-step heating and melting, thereby improving the performance of the final product.

[0180] (5) As can be seen from Application Example 1 and Comparative Application Examples 1-2, the equipment and method of the present invention are significantly superior to conventional solid-state method (ball milling + box furnace sintering) and wet spray drying method (slurry + box furnace sintering) in terms of density and ionic conductivity. Moreover, the entire process is solvent-free, green and environmentally friendly, and the production cycle is shortened from several days to several hours, which has good industrial application prospects.

[0181] In summary, this invention, in the preparation of lithium titanium aluminum phosphate, employs direct feeding of solid powder and achieves atomic / molecular-level homogeneous mixing of the powder raw materials through high-temperature hot melting. This fundamentally solves the component segregation problem caused by uneven mixing in solid-phase methods. Spherical precursor particles are then obtained through a spray cooling granulation unit. These spherical precursor particles exhibit good sphericity, adjustable particle size distribution, and smooth surfaces, possessing excellent flowability and packing density. This is beneficial for the uniformity of subsequent coating and sintering processes. Compared to hollow or broken particles obtained by wet spray drying, the spherical particles obtained by hot melting combined with spray cooling granulation are denser and stronger, resulting in a final lithium titanium aluminum phosphate density exceeding 97.1% and an ionic conductivity of 6.2 × 10⁻⁶. -4 With a strength of S / cm or higher, this invention integrates the entire process—from powder distribution to hot-melt homogenization, spray cooling granulation, coating modification, pulse activation to discharge plasma pulse sintering—into a single device. One-click process control is achieved through a control unit, eliminating the need for material transfer between different devices and avoiding the risks of moisture absorption, oxidation, and contamination of intermediate products. This greatly improves production efficiency and batch stability. Furthermore, the entire process does not use any organic solvents or water, consumes no energy for solvent removal, and generates no waste, achieving a completely dry and green production method for LATP preparation.

[0182] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. An apparatus for preparing lithium titanium aluminum phosphate, characterized in that, Along the material flow direction, the device includes a powder feeding unit, a hot melt homogenization unit, a spray cooling granulation unit, a coating modification unit, a pulse activation unit, and a discharge plasma pulse sintering unit connected in sequence.

2. The apparatus according to claim 1, characterized in that, The powder feeding unit includes at least four powder feeding devices; Preferably, the bottom of the powder feeding device is provided with a loss-in-weight metering feeder; Preferably, the device further includes a mixing guide channel connected to the loss-in-weight metering feeder; Preferably, the mixing guide channel includes a channel body and intermittent turbulence baffles disposed on the inner wall of the channel body; Preferably, the sidewalls of the tank are inclined along the axial direction of the mixing guide channel; Preferably, the angle between the sidewall of the trough and the axis of the mixing guide channel is 5~15°.

3. The apparatus according to claim 1 or 2, characterized in that, The hot-melting homogenization unit includes a melting crucible; Preferably, the hot melting homogenization unit further includes a first heating element covered on the outer wall of the melting crucible, a stirring device disposed inside the melting crucible, and a flow control valve disposed at the bottom outlet of the melting crucible; Preferably, the hot melting homogenization unit further includes a monitoring device disposed inside the melting crucible; Preferably, the hot-melting homogenization unit includes at least two monitoring devices; Preferably, different monitoring devices are installed at different depths in the smelting crucible.

4. The apparatus according to any one of claims 1-3, characterized in that, The spray cooling granulation unit includes a melt conveying pipeline, a melt pump, an atomizing device, a spray drying device, and a powder collecting device connected in sequence. Preferably, the outer side of the melt conveying pipeline is sequentially covered with a resistance heating strip and a heat insulation layer; Preferably, a pressure sensor and a temperature sensor are installed on the melt delivery pipeline; Preferably, the tower structure of the spray drying device is a vertical cylindrical shape; Preferably, the height-to-diameter ratio of the spray drying device is (3~8):1; Preferably, a cooling gas distributor is provided at the upper part of the spray drying device; Preferably, the powder collecting device includes a conical collecting hopper and a first feeding valve connected in sequence with the spray drying device; Preferably, the spray drying device includes an exhaust gas outlet; Preferably, the powder collection device further includes a separation device and a dust removal device connected in sequence to the exhaust gas outlet of the spray drying device.

5. The apparatus according to any one of claims 1-4, characterized in that, The coating modification unit includes a conical barrel, a second heating element covering the outer wall of the conical barrel, and a central rotating shaft disposed inside the conical barrel; Preferably, the blade is inclinedly arranged on the central rotating shaft along the axial direction of the central rotating shaft; Preferably, at least three layers of blades are provided on the central rotating shaft along its axial direction; Preferably, the angle between the blade and the axis of the central rotating shaft is 30~60°; Preferably, the gap between the outer edge of the blade and the inner wall of the conical barrel is 2~5mm; Preferably, the coating modification unit further includes a second discharge valve disposed at the bottom of the conical barrel.

6. The apparatus according to any one of claims 1-5, characterized in that, The pulse activation unit includes an insulating cavity, a first electrode and a second electrode disposed at both ends of the insulating cavity, a discharge grid plate disposed inside the insulating cavity, and a programmable pulse power supply connected to the first electrode and the second electrode respectively. Preferably, the insulating cavity is provided with 4 to 8 sets of staggered discharge grids; Preferably, the gap between adjacent discharge grid plates inside the insulating cavity is 0.5~3mm; Preferably, the staggered discharge grid plates are alternately connected to the first electrode and the second electrode; Preferably, the pulse activation unit further includes a third heating element covering the outer wall of the insulating cavity; Preferably, the discharge plasma pulse sintering unit includes a vacuum chamber and a first copper electrode, an upper pressure head, a graphite sintering mold, a lower pressure head, and a second copper electrode connected in sequence inside the vacuum chamber. Preferably, the discharge plasma pulse sintering unit further includes a DC pulse power supply connected to the first copper electrode and the second copper electrode; Preferably, the discharge plasma pulse sintering unit further includes a hydraulic pressing system connected to the upper pressure head and the lower pressure head respectively; Preferably, the device further includes a control unit, which is connected to the powder feeding unit, the hot melt homogenization unit, the spray cooling granulation unit, the coating modification unit, the pulse activation unit, and the discharge plasma pulse sintering unit.

7. A method for preparing lithium titanium aluminum phosphate, characterized in that, The preparation method is carried out using the apparatus for preparing lithium titanium aluminum phosphate as described in any one of claims 1-6.

8. The preparation method according to claim 7, characterized in that, The preparation method includes: The raw material mixture is subjected to hot melting homogenization treatment, spray cooling granulation treatment, coating modification treatment, pulse activation treatment and discharge plasma pulse sintering treatment in sequence to obtain the lithium titanium aluminum phosphate.

9. The preparation method according to claim 8, characterized in that, The preparation of the raw material mixture includes: first mixing lithium carbonate, aluminum oxide, titanium dioxide and phosphorus pentoxide to obtain the raw material mixture; Preferably, the molar ratio of lithium carbonate, alumina, titanium dioxide, and phosphorus pentoxide in the raw material mixture is (0.8~1.2):(0.15~0.35):(1.5~1.9):1; Preferably, the hot-melt homogenization treatment is carried out under the first stirring; Preferably, the rotation speed of the first stirring is 50~150 rpm; Preferably, the hot melt homogenization process includes a first hot melt homogenization process, a second hot melt homogenization process, and a third hot melt homogenization process performed sequentially; Preferably, the temperatures of the first hot melt homogenization treatment, the second hot melt homogenization treatment, and the third hot melt homogenization treatment increase sequentially; Preferably, the temperature of the second hot melt homogenization treatment is 200-410°C higher than the temperature of the first hot melt homogenization treatment; Preferably, the temperature of the third hot-melt homogenization treatment is 100-500°C higher than the temperature of the second hot-melt homogenization treatment; Preferably, the temperature of the first hot-melt homogenization treatment is 340~400℃; Preferably, the heat preservation time for the first hot-melt homogenization treatment is 10~30 min; Preferably, the temperature of the second hot-melt homogenization treatment is 600~750℃; Preferably, the holding time for the second hot-melt homogenization treatment is 20-40 minutes; Preferably, the temperature of the third hot-melt homogenization treatment is 850~1100℃; Preferably, the holding time for the third hot-melt homogenization treatment is 30~90 min; Preferably, the temperature of the cooling gas used in the spray cooling granulation process is 0~80℃; Preferably, the spray cooling granulation process takes 1 to 10 minutes; Preferably, the precursor powder is obtained after the spray cooling granulation treatment; Preferably, the average particle size D50 of the precursor powder is 50~100μm.

10. The preparation method according to claim 8 or 9, characterized in that, The coating modification treatment is performed at a temperature of 300~450℃; Preferably, the coating modification treatment is carried out under a second stirring. Preferably, the second stirring speed is 1000~3000 rpm; Preferably, the second stirring time is 30~120 min; Preferably, the pulse current of the pulse activation treatment is 500~5000A; Preferably, the pulse voltage of the pulse activation treatment is 5~20V; Preferably, the frequency of the pulse activation treatment is 10~500Hz; Preferably, the temperature of the pulse activation treatment is 150~400℃; Preferably, the pulse activation treatment time is 5-60 min; Preferably, the material in the pulse activation process accounts for 10-90% of the volume of the insulating cavity in the pulse activation unit; Preferably, the vacuum degree of the discharge plasma pulse sintering process is ≤6.7×10⁻⁶. -3 Pa; Preferably, the pressure of the discharge plasma pulse sintering treatment is 10~200MPa; Preferably, the pulse current of the discharge plasma pulse sintering treatment is 3000~30000A; Preferably, the pulse voltage of the discharge plasma pulse sintering treatment is 3~10V; Preferably, the heating rate of the discharge plasma pulse sintering treatment is 100~200℃ / min; Preferably, the temperature of the discharge plasma pulse sintering treatment is 800~1000℃; Preferably, the holding time for the discharge plasma pulse sintering treatment is 2 to 10 minutes.

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