A method and system for producing a positive electrode material for a sodium ion battery

Abstract

The present application relates to the technical field of sodium ion batteries, and specifically provides a method and system for making a positive electrode material for a sodium ion battery. The method comprises the following steps: weighing each raw material according to a preset molar ratio, each raw material including a sodium source and one or more compound raw materials containing transition metal elements; crushing each raw material to a preset size using a first gas crushing system; dry mixing each crushed raw material; sintering the mixed raw material to obtain a sodium-containing oxide; crushing and screening the sodium-containing oxide using a dry material crushing and screening system to obtain a layered oxide type sodium positive electrode material. The whole process is a dry process, without the need to add a solvent, remove the solvent, and dry before firing, which significantly simplifies the manufacturing process, and there is no grinding impurity mixing, which improves the raw material purity and product purity, and can improve the mixing effect, improve the reaction sufficiency of each raw material during sintering, and improve the finished product quality and electrochemical performance of the sintered product.

Description

Technical Field

[0001] The present application relates to the technical field of sodium ion batteries, and in particular to a method and system for manufacturing a positive electrode material for a sodium ion battery. Background Art

[0002] Sodium-ion battery is a secondary battery (rechargeable battery) that mainly relies on the movement of sodium ions between the positive electrode and the negative electrode to work. During the charge and discharge process, Na ions are embedded and extracted back and forth between the two electrodes. The most important feature of sodium-ion batteries is that they use sodium ions instead of expensive lithium ions. Therefore, the positive electrode material, negative electrode material and electrolyte of the battery must be changed accordingly to adapt to the mobility characteristics of sodium ions. Due to the change in the positive electrode material of the battery, its preparation process also has its own unique requirements and cannot be simply made using the lithium ion preparation process.

[0003] At present, in the production of sodium ion battery positive electrode materials, when crushing and mixing sodium raw materials and transition metals and other raw materials, each raw material is mainly mixed by wet method, that is, firstly, each solid raw material is mixed with a solvent that acts as a lubricant, and then ground by a mixer such as a sand mill and a ball mill, so that each raw material is crushed and mixed in the solvent to form a slurry, and then it is necessary to dry it to remove the solvent in the slurry and dry the mixture to achieve the sintering premise, and then the mixture can be sintered at high temperature to obtain the required material prototype. This wet mixing process is not only cumbersome, but also in the process of grinding and crushing, it is easy to mix into the grinding medium, and the grinding chamber is also easy to be worn, resulting in the wear-away substances being doped into the slurry as impurities, which will affect the purity of the slurry and the electrochemical properties of the final material. Summary of the invention

[0004] In view of this, the embodiments of the present application are dedicated to providing a method for preparing sodium battery materials to solve the problem in the prior art that the wet mixing process is cumbersome and easily leads to impurities mixed in the material and affects the performance.

[0005] On the one hand, the present application provides a method for preparing a positive electrode material for a sodium ion battery, comprising the following steps:

[0006] Weighing raw materials according to a preset molar ratio, wherein the raw materials include a sodium source and one or more compound raw materials containing transition metal elements;

[0007] Using a first gas crushing system to crush each raw material into a preset particle size;

[0008] The crushed raw materials are mixed using a dry material mixing device to obtain a mixed raw material;

[0009] Using a sintering system to sinter the mixed raw materials in a gas environment to obtain a sodium-containing oxide;

[0010] The sodium-containing oxide is crushed and screened using a dry material crushing and screening system to obtain the desired layered oxide-type sodium positive electrode material.

[0011] In a possible implementation, the use of the first gas crushing system to crush the raw materials into a preset particle size includes the following:

[0012] Grouping the raw materials according to their hardness levels into components of different hardness levels;

[0013] The raw materials of each component are added to the same pulverizing system through different pulverizing paths to achieve pulverization and mixing, wherein the different pulverizing paths have different pulverizing strengths, and the raw materials of each component are added to the pulverizing path with a pulverizing strength level adapted thereto according to the hardness level.

[0014] In a possible implementation, the dry material mixing equipment includes an air flow mixer; and / or the dry material crushing and screening system is a second air crushing system.

[0015] In a possible implementation, the method further includes: using the same induced draft duct to introduce the raw materials gas-crushed by the first gas-crushing system into the air flow mixer, so that the gas-crushed raw materials are subjected to primary mixing in the induced draft duct and secondary mixing in the air flow mixer.

[0016] In a possible implementation, the method further includes: performing dust removal treatment on the airflow discharged in each of the above steps, and using the purified airflow after the dust removal treatment as a circulating air source for recycling.

[0017] In a possible implementation, the method further includes: using a heat exchange system to recover heat from the tail gas discharged from the sintering system, and using the recovered heat to heat the circulating gas source used for crushing the material.

[0018] In a possible embodiment, the compound raw material includes an iron source, a manganese source, a nickel source and a doping element, and the molar ratio of the sodium source, the iron source, the manganese source, the nickel source and the doping element is 1-1.1:0.2-0.9:0.05-0.9:0.1-0.9:0-0.1; wherein the molar ratio of the sodium source to the compound raw material is 1-1.1:1.

[0019] In a possible embodiment, the sodium source is one or more of sodium carbonate, sodium dihydrogen phosphate, sodium sulfate, sodium nitrate, sodium hydroxide, sodium acetate, and sodium oxalate; the manganese source is one or more of manganese dioxide, manganese tetraoxide, manganese trioxide, manganese oxalate, manganese sulfate, manganese carbonate, and manganese nitrate; and the doping element is one or more of copper, titanium, magnesium, vanadium, niobium, lithium, aluminum, tungsten, molybdenum, chromium, silicon, strontium, zirconium, boron, zinc, and calcium.

[0020] In a possible implementation, when the mixed raw material is sintered in a gas environment using a sintering system, the sintering temperature is 500 to 1200° C. and the sintering time is 8 to 24 hours;

[0021] Alternatively, when the mixed raw materials are sintered in a gas environment using a sintering system, a first sintering is performed at a temperature of 600-1100° C. for 2-12 hours; and then a second sintering is performed at a temperature of 500-900° C. for 2-12 hours.

[0022] In a possible implementation, the first gas crushing system includes at least one multi-material crusher or a plurality of single-material gas crushers, and the multi-material crusher is provided with at least two layers of crushing paths arranged along the height direction of the crushing chamber.

[0023] On the other hand, the present application also provides a sodium ion battery positive electrode material production system, including: a first gas crushing system, having a crushing chamber and a crushing path for materials and airflow to enter the crushing chamber, for crushing raw materials; an airflow mixer, connected to the material outlet of the first gas crushing system through an induced draft duct, for mixing the crushed raw materials; a sintering system, including a primary sintering device and a secondary sintering device, for receiving the mixed raw materials discharged from the airflow mixer and sintering the mixed raw materials; a dry material crushing and screening system, for crushing and screening the products of the sintering system.

[0024] In one possible embodiment, the dry material crushing and screening system includes a second gas crushing system for crushing the sodium-containing oxide, and the production system also includes: a first dust removal system, the exhaust gas inlet is connected to the exhaust ports of the first gas crushing system and the airflow mixer respectively, and the clean gas outlet is connected to the air inlet of the first gas crushing system; a second dust removal system, the exhaust gas inlet is connected to the exhaust port of the second gas crushing system, and the clean gas outlet is connected to the air inlet of the second gas crushing system; a heat exchange system, having a heat recovery pipeline for absorbing the heat of the gas exhausted by the sintering system, a first heat supply pipeline for supplying heat to the first gas crushing system, and a second heat supply pipeline for supplying heat to the second gas crushing system.

[0025] In a possible embodiment, the first gas crushing system includes a multi-material crusher, and a crushing chamber of the multi-material crusher is provided with a material outlet, a classifying wheel, and a first crushing path and / or a second crushing path; the first crushing path includes a feed layer and an air intake layer, the feed layer includes at least one first material nozzle, and the air intake layer includes at least two first airflow nozzles arranged along the circumference of the crushing chamber; the second crushing path is a mixed feed layer, at least one layer is provided in the height direction, and includes at least two combination nozzles arranged along the circumference of the crushing chamber, and a second airflow nozzle and a second material nozzle are formed on the nozzle body of the combination nozzle, wherein the second material nozzle and the second airflow nozzle are nested, or, the second airflow nozzle and the second material nozzle are close to each other in the direction close to the nozzle; the classifying wheel is located in the crushing chamber and is arranged at the material outlet, so that the material particles reach a preset size and are ejected through the material outlet.

[0026] In a possible embodiment, at least two second air flow nozzles are provided on the same combined nozzle, and the at least two second air flow nozzles are arranged along the circumference of the second material nozzle and arranged around the second material nozzle, and the extension lines of the axes of each second air flow nozzle converge to the same point.

[0027] In a possible implementation, in the height direction of the pulverizing chamber, the material outlet is opened at the top, the first pulverizing path and / or the second pulverizing path are provided with at least two layers, and each of the second pulverizing paths is located below all of the first pulverizing paths.

[0028] According to the preparation method of sodium electric material provided in the present application, each raw material is crushed by gas crushing, and each raw material is crushed to the required particle size to ensure that each raw material can be mixed evenly and thoroughly, and the mixing of each raw material is also dry mixing, and then the thoroughly crushed raw materials are mixed by dry material mixing equipment such as air flow mixer or plowshare mixer, which can improve the mixing degree and mixing effect of each material. During the whole crushing and mixing process, no solvent needs to be added, and no grinding medium needs to be intervened. Impurities will not be mixed into the raw materials, which can improve the purity of the raw materials and the purity of the final product; and after the raw materials are evenly mixed, they are sintered, and after sintering, further dry material crushing such as gas crushing and screening is carried out to obtain the required positive electrode material. The entire raw material processing process is a dry process. When crushing and mixing, there is no need to add solvents, grind, remove solvents, or dry before sintering, which significantly simplifies the production process of positive electrode materials for sodium ion batteries and reduces complexity. At the same time, materials of different hardness are crushed to the required fine particle size by gas crushing and dry mixing is performed. On the one hand, no impurities are mixed into the raw materials, which can improve the purity of the raw materials and the purity of the final product, thereby improving the electrochemical properties of the resulting positive electrode materials. On the other hand, the mixing effect is not adversely affected by the addition and removal of solvents, which can ensure that the raw materials are mixed evenly and thoroughly. The raw materials of different hardness are evenly mixed in fine particles and then sintered, which can improve the reaction sufficiency of each raw material and the quality of the finished product of the sintered product, thereby improving the electrochemical properties of the resulting positive electrode materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The figure shows a production flow chart of the positive electrode material for a sodium ion battery in an embodiment of the present application;

[0030] Figure 2 Shown is a schematic diagram of a system for manufacturing a positive electrode material for a sodium ion battery in an embodiment of the present application;

[0031] Figure 3 Shown is a schematic diagram of a multi-material pulverizer in an embodiment of the present application;

[0032] Figure 4 It is a schematic diagram of the combined nozzle in the first direction in the embodiment of the present application;

[0033] Figure 5 Shown is a half-section schematic diagram of a combined nozzle in an embodiment of the present application;

[0034] Figure 6 It is a schematic diagram of the second direction of the combined nozzle in the embodiment of the present application;

[0035] Figure 7 Shown is a comparison chart of XRD spectra of Test Example 1 and Comparative Example 1 in the embodiments of the present application;

[0036] Figure 8 Shown is a comparison chart of the charge and discharge cycle curves of Test Example 1, Comparative Example 1, and Comparative Example 2 in the embodiments of the present application;

[0037] Fig. 9 Shown is a SEM electron microscope photograph of the product obtained in Test Example 1 in the examples of this application.

[0038] Figure 1-9 middle:

[0039] 10. First gas crushing system; 20. Air flow mixer; 30. Sintering system; 40. First dust removal system; 50. Second dust removal system; 60. Second gas crushing system; 70. Heat exchange system; 80. First gas source treatment system; 90. Second gas source treatment system; 100. Tail gas treatment system;

[0040] 11. Multi-material pulverizer; 1. pulverizing chamber; 101. material outlet; 2. first material nozzle; 3. first air flow nozzle; 4. combined nozzle; 41. nozzle body; 42. second material nozzle; 43. second air flow nozzle; 431. wide diameter section; 432. narrow diameter section; 433. nozzle; 44. mounting plate; 5. grading wheel. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0042] Please refer to the attached Figure 1-9 The embodiment of the present application provides a method for manufacturing a positive electrode material for a sodium ion battery, the method comprising the following steps:

[0043] S01, weighing various raw materials according to a preset molar ratio, the raw materials including a sodium source and one or more metal element raw materials in transition metals (transition metals refer to transition metals in the periodic table, such as chromium, manganese, iron, cobalt, nickel, copper, zinc, palladium, silver, platinum, gold, mercury, etc.);

[0044] S02, using a first gas crushing system to weigh the assembled raw materials in molar ratio and crush them into a preset particle size, for example, all raw materials with different hardness are crushed into fine particles;

[0045] S03, using a dry material mixing device to mix the crushed raw materials, so that the various raw materials that have been crushed into granules or powders are evenly mixed together to obtain a mixed raw material;

[0046] S04, using a sintering system to sinter the mixed raw materials in a gas environment. The gas environment is determined according to the needs, and can be an oxygen environment, an inert gas environment, or directly an air environment. The sintering can be a single sintering, for example, the sintering temperature is 500-1200°C, and the sintering time is 8-24h, or it can be multiple sinterings. For example, the first sintering is performed first, and the temperature of the first sintering is 600-1100°C, and the sintering time is 2-12h; then the second sintering is performed, and the temperature of the second sintering is 500-900°C, and the sintering time is 2-12h, so that the raw materials react chemically at high temperature and are combined into a sintered product containing sodium and transition metals, which is called sodium-containing oxide;

[0047] S05, using a dry material crushing and screening system to dry-crush and grade the sodium-containing oxide obtained after sintering, and obtain a layered oxide type sodium positive electrode material, that is, a layered oxide type sodium positive electrode material (sodium ion battery positive electrode material, referred to as sodium positive electrode material) containing sodium and transition metals of the required size. The layered oxide type refers to the arrangement of transition metals in the material lattice state layer by layer. However, macroscopically, the layered oxide type sodium positive electrode material is a granular powder.

[0048] The method first crushes each raw material by gas crushing, which can be either crushed separately or crushed together. For example, crushing is performed in the same or connected crushing chamber by crushing paths (or, cavity entry paths, i.e., paths entering the crushing chamber) with different crushing forces, ensuring that all raw materials with different hardness are crushed to the required particle size, such as the particle size required for sintering, with good crushing effect and controllable particle size, ensuring that each raw material can be crushed and mixed uniformly. There is no need to add solvent as a lubricating medium, nor is there any need to use grinding media such as grinding rods for grinding. And the mixing of each raw material is also dry mixing, such as mixing the thoroughly crushed raw materials through dry material mixing equipment such as air flow mixers or plowshare mixers, so that the raw materials in fine particle form are fully and thoroughly mixed, which can improve the mixing degree and mixing effect of each material and ensure the uniformity of the raw materials. And there is no need to mix in a solvent, so there is no need to dry after mixing to remove the solvent and achieve the drying conditions required for sintering. The sodium oxide generated after sintering the mixed raw materials is also dry crushed and screened using a dry material crushing and screening system to obtain the required positive electrode material. The entire process is a dry process.

[0049] With such arrangement, on the one hand, the entire production process is a dry process. Compared with the wet mixing in the prior art, there is no need to add solvents during crushing and mixing, nor is there any need to remove solvents or dry before sintering. The dry mixed raw materials obtained by the first gas crushing system and the dry mixing equipment can meet the requirements of particle size and dryness required for sintering, and can be directly sintered. After sintering, the required positive electrode material can be obtained by crushing and screening the dry materials, which significantly simplifies the production process of positive electrode materials for sodium ion batteries and reduces the complexity. No solvent is required throughout the process, which significantly reduces wastewater discharge and does not require a complex wastewater purification system. On the other hand, the raw materials are crushed by gas crushing without adding solvents or using grinding media for grinding, which avoids impurities mixed into the raw materials due to incomplete removal of wear materials and solvents, thereby improving the purity of the raw materials. The improvement of the purity of the raw materials can not only promote the reaction sufficiency of each raw material during sintering, but also improve the purity of the final positive electrode material, thereby improving the performance of the obtained positive electrode material. On the third hand, the materials of different hardness are crushed to the required fine particle size by gas crushing and then subjected to Good mixing, controllable and adjustable particle size, can be crushed to the required particle size, and the raw materials can be mixed evenly and thoroughly, which can improve the mixing degree and mixing effect of each material. In the wet mixing in the prior art, the particle size needs to be controlled by the sanding time, and there may be different particle sizes. When the mixed slurry is subjected to solvent removal and pre-firing drying, a solvent rapid evaporation system must be equipped, otherwise raw materials with different molar ratios are easy to stratify, resulting in poor final mixing effect. In the present application, gas crushing and dry mixing are used, which are not affected by the adverse effects of solvent addition and removal operations on the mixing effect, and can ensure that the raw materials are mixed evenly and thoroughly, and the degree of mixing affects the subsequent sintering effect. The thorough and uniform good mixing effect of the raw materials achieved in the present application can avoid the problem of insufficient reaction during high-temperature sintering due to insufficient crushing of some raw materials with higher hardness or incomplete mixing of the raw materials. In the present application, the raw materials with different hardness are uniformly mixed in fine particles and then sintered, which can improve the reaction sufficiency of each raw material, improve the quality of the finished product of the sintered product, and improve the electrochemical properties of the obtained positive electrode material.

[0050] It can be seen that the method for preparing the positive electrode material for a sodium ion battery provided in the present application not only significantly simplifies the production process and reduces the complexity, but also can improve the purity and quality of the final positive electrode material and improve the chemical properties of the obtained positive electrode material.

[0051] When the raw materials are gas-crushed by the first gas-crushing system, the gas-crushing can be performed once or multiple times (multiple times means two or more times). For example, the gas-crushing is performed in a first-stage gas-crusher first, and then the crushed raw materials enter a second-stage gas-crusher for secondary gas-crushing. After the multiple-stage gas-crushing is completed, they are introduced into the dry material mixing equipment for mixing.

[0052] The sodium source in the raw material is a sodium-containing compound, which can be one compound or multiple compounds, such as one or more of sodium carbonate, sodium dihydrogen phosphate, sodium sulfate, sodium nitrate, sodium hydroxide, sodium acetate, and sodium oxalate.

[0053] Transition metals may include iron, manganese, nickel, and may also include doping elements, which may include one or more of copper Cu, titanium Ti, magnesium Mg, vanadium V, niobium Nb, lithium Li, aluminum Al, tungsten W, molybdenum Mo, chromium Cr, silicon Si, strontium Sr, zirconium Zr, boron B, zinc Zn, and calcium Ca. Transition metals can be obtained from compounds containing the desired metals, such as oxides or salts. For example, the raw material includes one or more compounds of an iron source, a manganese source, and a nickel source, and may also include one or more compounds containing doping elements. For example, the manganese source may be one or more of manganese dioxide, manganese tetraoxide, manganese trioxide, manganese oxalate, manganese sulfate, manganese carbonate, and manganese nitrate. The nickel source may be one or more of nickel sulfate, nickel nitrate, nickel monoxide, nickel oxide, and nickel hydroxide, and the iron source may be one or more of ferric oxide, ferric sulfate, ferric hydroxide, and ferric oxide.

[0054] Different application scenarios of sodium-ion batteries will lead to deviations in the performance requirements of sodium-ion batteries, such as the first coulombic efficiency, first discharge capacity, discharge rate, charge and discharge cycle performance, etc., which will also lead to differences in the composition elements and proportions of the positive electrode materials. During preparation, different raw material compositions and proportions can be selected according to the performance requirements of the required positive electrode materials.

[0055] In some embodiments, the sodium source, iron source, manganese source, nickel source, and doping element R are prepared according to an element molar ratio of m (Na: Fe: Mn: Ni: R) = 1-1.1: 0.2-0.9: 0.05-0.9: 0.5-0.9: 0-0.1 (where 0 means no doping element), wherein the sum of the element molar ratios of Fe, Mn, and Ni is 1, and the element molar ratio of the sodium source to other compound raw materials is 1-1.1: 1, and each raw material is weighed separately.

[0056] For example, sodium carbonate, iron oxide, nickel oxide, and manganese oxide are weighed in a molar ratio of 1.1:0.15:0.8:0.05, and mixed by gas crushing according to the above method, and sintered at 700 degrees for 20 hours. The obtained sodium-containing oxide is crushed and sieved to obtain a layered oxide sodium positive electrode material with a particle size between 1-5 μm, such as Fig. 9 The electron microscope photo shows that the obtained layered oxide sodium positive electrode material has uniform particles and a uniform particle size. The amount of metal elements embedded in the crystal lattice of the obtained layered oxide sodium positive electrode material is large and uniform, the material has a large charge and discharge capacity, and good cycle charge and discharge performance.

[0057] In order to improve the degree of crushing and mixing of each raw material, when selecting raw materials, you can also choose raw materials with a particle size within a certain range, such as a particle size of 30μm-3mm, and use gas crushing to crush the raw materials. The optimal feed particle size of the gas crusher may not be higher than 3mm.

[0058] When using the first pneumatic crushing system to crush the various types of weighed raw materials into the required particle size, the raw materials with different hardness can be crushed separately (for example, each type of raw material is crushed using a single-material pneumatic crusher) and then mixed, or multiple materials with different hardness can be crushed in the same batch (for example, a multi-material crusher with multiple crushing paths is used to crush and mix the raw materials in the same batch).

[0059] For example, the raw materials to be proportioned are grouped according to their hardness levels and divided into components of different hardness levels; then the raw materials of each component are added to the same pulverizing system (such as a pulverizing chamber) through different pulverizing paths to achieve pulverization and mixing, wherein different pulverizing paths have different pulverizing forces, which can make the materials produce different impact forces and different pulverizing effects, and the pulverizing force is proportional to the impact force and the pulverizing effect. The raw materials of each component are added to the pulverizing paths arranged according to the pulverizing force according to the hardness level, so that the pulverizing force level is adapted to its hardness level.

[0060] That is, among the raw materials, they are classified and grouped according to the hardness range, one or several raw materials with similar hardness are grouped together, and then a group of raw materials with higher hardness are added to the crushing path with greater crushing force, and raw materials with lower hardness are added to the crushing path with lower crushing force. The crushing paths are arranged in levels according to the strength, and the raw materials are arranged in levels according to the hardness. They are adapted according to the levels. The hardest raw materials are added to the crushing system through the path with the greatest crushing force, the second hardest raw materials are added to the crushing system through the path with the second strongest crushing force, and the raw materials with the smallest hardness are added to the crushing system through the path with the smallest crushing force. Since each crushing path is connected to the same crushing chamber, the crushing path can also be called the cavity entry path. After the material enters the crushing chamber, it will collide for the first time under the impact of the airflow ejected by the crushing path and be crushed. The greater the force of the first collision (the impact force is related to factors such as material speed and airflow speed), the better the crushing effect and the greater the crushing force of the path.

[0061] Therefore, by adding multiple raw materials of different hardness in different paths, the raw materials with high hardness are matched with the paths with high crushing strength, and the raw materials of different hardness can be crushed in the same crushing chamber. By ensuring different crushing strengths, it can not only ensure that each raw material is crushed to the required particle size and the crushing effect is ensured, but also can be mixed during the crushing process. The material discharged from the first crushing equipment is already a mixed raw material that has been preliminarily mixed, and coupled with the re-mixing through the dry material mixing equipment, the overall mixing time is increased, and the mixing effect is improved.

[0062] The dry material mixing equipment may be an air flow mixer or a plowshare mixer. In some embodiments, an air flow mixer is used to mix the materials discharged from the first gas crushing system. Both are gas path equipment and can share a gas path system. For example, the air flow discharged from the first gas crushing system and the air flow mixer is treated by the dust removal and air source treatment system, and then re-enters the first gas crushing system and the air flow mixer as a circulating air source to blow the raw materials. In the embodiment using the air flow mixer, after the first gas crushing system is used to crush the raw materials, the crushed raw materials are introduced into the air flow mixer through the same induced air duct for mixing. In this way, under the blowing of the air flow, the raw materials will be converged and mixed in the induced air duct, and then continue to be mixed in the air flow mixer. The air flow sprayed from the bottom of the mixer will drive the raw materials to tumble again, so that the raw materials can convect, diffuse, and mix, so that a variety of raw materials in the form of fine particles can be thoroughly and evenly mixed.

[0063] In some embodiments, each raw material can be crushed separately, or each raw material can be grouped according to hardness range, raw materials with similar hardness can be grouped into the same group, and each group of raw materials can be crushed separately. Before crushing each group of raw materials, the raw materials in the same group are first mixed, and then added into the gas crusher for crushing.

[0064] When the raw materials crushed by the first gas crushing system are introduced into the air flow mixer, the raw materials are gathered through the same induced air duct and the gathered mixed raw materials are introduced into the air flow mixer for mixing. The raw materials may be partially mixed during gas crushing, and then primary mixing is performed in the induced air duct, and secondary mixing is performed in the air flow mixer.

[0065] When the raw materials are grouped according to their hardness levels, the raw materials of the same group are preliminarily mixed before crushing, and then the preliminarily mixed raw materials of each component are added to the same crushing chamber through different crushing paths for crushing and mixing in the same batch, and then the mixed raw materials are introduced into the air flow mixer through the same induced draft duct for re-mixing. The raw materials are preliminarily mixed before crushing, mixed during crushing, mixed in the duct and mixed in the air flow mixer, and multi-stage mixing is carried out. Compared with the existing technology, the mixing uniformity and mixing effect of the raw materials are improved.

[0066] The sintering system may sinter the mixed raw materials once or twice or more, for example, including a primary sintering device and / or a secondary sintering device to sinter the raw materials. The primary sintering device and the secondary sintering device may be a roller kiln, a push plate kiln, a rotary kiln, a box furnace, a tube furnace, etc.

[0067] When the sintered product, i.e., the sodium oxide, is crushed and screened, the second gas crushing system can be used for gas crushing and screening, or a jaw crusher, a roll crusher, a hammer crusher, a rod mill, a centrifugal mill and other crushing equipment can be used for crushing and screening.

[0068] Taking the use of the second gas crushing system for gas crushing and screening as an example, the particle size of the crushed particles containing sodium oxide is controllable and adjustable, which can not only obtain small-particle-size layered oxide-type sodium battery positive electrode materials, but also adjust the particle size according to needs.

[0069] Therefore, in the production of positive electrode materials for sodium ion batteries, a dry process of gas crushing-gas mixing-sintering-gas crushing and screening can be adopted. The production system used includes a first gas crushing system, an air flow mixer, a sintering system, and a second gas crushing system. On the one hand, not only is the process simple and does not require the discharge of wastewater, but also no medium is introduced during the crushing and mixing process, which improves the purity of the raw materials and the purity of the product; on the other hand, the crushing and mixing method of gas crushing and gas mixing can not only crush raw materials of different hardness into small particles with controllable particle size, but also ensure the crushing and mixing effects, improve the reaction sufficiency during sintering, and improve the electrochemical properties of the final product, i.e., the positive electrode material; on the third hand, the entire production system can form a closed system, such as Figure 2 As shown, the raw materials after gas crushing and gas mixing are directly introduced into the closed sintering equipment, and after sintering, they are directly sent to the second gas crushing system for gas crushing and screening to obtain the finished product, which is especially suitable for products that need to be sintered in a gas environment. The entire production process, raw materials and products are completed in a closed system. In this way, the economy and environmental protection can be greatly improved.

[0070] In some embodiments, the method for producing a positive electrode material for a sodium ion battery further includes the following: performing dust removal treatment on the airflow discharged in each of the above steps, and using the purified airflow after the dust removal treatment as a circulating air source for the gas crushing system for recycling.

[0071] For example, the first dust removal system is used to purify the gas exhausted from the first gas pulverizing system and the air flow mixer, and the purified air flow is used as at least a circulating air source for the first gas pulverizing system and the air flow mixer.

[0072] The second dust removal system is used to purify the gas exhausted by the second gas pulverization system, and the purified gas flow is used as at least a circulating gas source for the second gas pulverization system.

[0073] In this way, the airflow can be recycled to save costs. More importantly, the first gas crushing system, the airflow mixer and the first dust removal system can form a first closed circulation gas circuit, the second gas crushing system and the second dust removal system can form a second closed circulation gas circuit, or all the gas crushing, air mixing and dust removal systems can form a closed circulation gas circuit as a whole, and the sintering system can also introduce inert gas or other gases such as oxygen as needed, and the entire production system can form a closed system.

[0074] In some embodiments, the method for making a positive electrode material for a sodium ion battery further includes the following: using a heat exchange system to recover heat from the tail gas discharged from the sintering system, and using the recovered heat to heat the circulating gas source used to crush the material. When the first gas crushing system is used to crush the raw materials, and the second gas crushing system is used to crush the sodium oxide obtained by sintering, the heat recovered by the heat exchange system is used to heat the gas sources of the first gas crushing system and the second gas crushing system, respectively, such as preheating the air intake pipe or air intake, or directly heating the airflow. Using the recovered heat to heat the airflow used to crush the material can save energy and improve the crushing and mixing effects of the material.

[0075] In this way, the production process of sodium ion battery positive electrode materials can be as follows Figure 1 As shown, it has economic and environmental benefits.

[0076] The embodiment of the present application also provides a system for manufacturing a positive electrode material for a sodium ion battery, which can use the above-mentioned method for manufacturing a positive electrode material for a sodium ion battery to manufacture a positive electrode material for a sodium ion battery. Figure 2 As shown, the manufacturing system includes a first gas crushing system 10, an air flow mixer 20, a sintering system 30 and a dry material crushing and screening system. The first gas crushing system 10 is the first gas crushing system 10 in the embodiment of the above method, which has a crushing chamber and a crushing path for materials and air flow to enter the crushing chamber, and is used to crush each raw material to a set particle size. The crushing chamber is provided with a material outlet 101, and the material crushed to a preset size can be discharged from the material outlet 101. The feed port of the air flow mixer 20 is connected to the material outlet 101 of the first gas crushing system 10 through an induced draft duct, so that the crushed material enters the mixing chamber for mixing, so that the crushed raw materials are evenly mixed. The sintering system 30 includes a primary sintering device and a secondary sintering device to receive the mixed raw materials discharged from the air flow mixer 20 and sinter the mixed raw materials to generate sodium-containing oxides. The dry material crushing and screening system is used to crush and screen the sodium-containing oxides obtained by sintering. In this way, the production system produces the positive electrode material of the sodium ion battery according to the production method described in the above embodiment, so it has the beneficial effects of the production method described in the above embodiment, which will not be repeated here.

[0077] In some embodiments, the manufacturing system further includes a first dust removal system 40, a second dust removal system 50 and a heat exchange system 70. A first gas source treatment system 80 is provided at the first gas pulverization system 10, and a second gas source treatment system 90 is provided at the second gas pulverization system 60. The exhaust gas inlet of the first dust removal system 40 is respectively connected to the exhaust ports of the first gas pulverization system 10 and the air flow mixer 20, and the clean gas outlet is connected to the air inlet of the first gas source treatment system 80. The air outlet of the first gas source treatment system 80 is respectively connected to the air inlet of the first gas pulverization system 10 and the air flow mixer 20. In this way, the gas discharged from the first gas pulverization system 10 and the air flow mixer 20 is purified, and the purified gas is supplied to the first gas source treatment system 80 through the air intake pipe of the first gas pulverization system 10, forming a circulating gas source, and continuing to supply the first gas pulverization system 10 and the air flow mixer 20, so that the air flow can be recycled. Similarly, the exhaust gas inlet of the second dust removal system 50 is connected to the exhaust port of the second gas pulverization system 60, the clean gas outlet is connected to the air inlet of the second gas source treatment system 90, and the air outlet of the second gas source treatment system 90 is connected to the air inlet of the second gas pulverization system 60, so that the purified gas forms a circulating gas source. The sintering system 30 may also be provided with an exhaust gas treatment system 100 to purify the exhaust gas discharged from the sintering system. The heat exchange system 70 has a heat recovery pipeline for absorbing the heat of the gas discharged from the sintering system 30, a first heat supply pipeline for supplying heat to the first gas pulverization system 10, and a second heat supply pipeline for supplying heat to the second gas pulverization system 60. The purified gas discharged from the first dust removal system 40 can first absorb heat through the first heat supply pipeline and then enter the first gas source treatment system 80, and the purified gas discharged from the second dust removal system 50 can first absorb heat through the second heat supply pipeline and then enter the second gas source treatment system 90. In this way, the heat in the tail gas discharged from the sintering system 30 is recovered and used to heat the gas used to impact the materials in the first gas crushing system 10 and the second gas crushing system 60 respectively. The hot air flow is used to crush the materials, so that a better crushing effect can be achieved.

[0078] In some embodiments, Figure 2 As shown, the first gas crushing system 10 includes a multi-material crusher 11, which is used to crush a variety of raw materials with different hardness in the same batch. Figure 3 As shown, the pulverizing chamber 1 of the multi-material pulverizer 11 is provided with a material outlet 101 and a classifying wheel 5, and is provided with a first pulverizing path and / or a second pulverizing path. The classifying wheel 5 is arranged in the pulverizing chamber 1 and is located at the material outlet 101, as shown in FIG. Figure 2 The inner side of the material outlet 101 (the side closer to the inside of the grinding chamber) shown in the figure controls the discharge particle size so that the raw material particles can be discharged through the material outlet 101 only after reaching a preset size.

[0079] like Figure 3As shown, in some embodiments, in the height direction of the pulverizing chamber, the material outlet 101 is arranged at the top of the pulverizing chamber 1, for example, on the top wall, and the classifying wheel 5 can be provided with at least two groups, which are arranged horizontally on both sides of the material outlet 101. Particles that meet the particle size requirements can be discharged through the classifying wheel 5, while large particles that do not meet the particle size requirements will be thrown out by the high-speed rotating classifying wheel 5 and returned to the pulverizing chamber 1 for further gas crushing, so that the material particles can only be ejected through the material outlet 101 after reaching the preset size. Such a setting can ensure that the material can be discharged from the pulverizing chamber 1 only after it meets the pulverization requirements, that is, pulverized to the set particle diameter range, thereby ensuring the pulverization quality.

[0080] The first pulverizing path includes a feed layer and an air intake layer. The feed layer includes at least one first material nozzle. When at least two first material nozzles are provided, they are arranged along the circumference of the pulverizing chamber 1. The first material nozzle 2 is a material port for the raw material to enter the pulverizing chamber 1, and is connected to a second feed member (such as a screw feeder) for pushing the raw material forward to provide the raw material into the pulverizing chamber 1. The air intake layer includes at least two first airflow nozzles 3 arranged along the circumference of the pulverizing chamber 1. The first airflow nozzle 3 is used to be connected to a first air supply component (such as an air source and an air pump) to eject a high-pressure and high-speed airflow. The extended lines of the axes of each first airflow nozzle 3 on the same pulverizing path converge to the same point. High-speed airflows in different directions collide at the same point.

[0081] The first material nozzle 2 and the first airflow nozzle 3 are separately arranged, and feed and spray air separately. For example, the feed layer is located above the air intake layer, that is, the first material nozzle 2 is arranged above the first airflow nozzle 3. The raw material to be crushed tends to fall after entering the crushing chamber 1 from the first material nozzle 2. The airflow sprayed by the first airflow nozzle 3 arranged in different directions impacts the raw material, carrying the raw material to the convergence point, so that the raw materials in different directions collide with each other for the first time and crush them. The crushed raw materials collide again and multiple times under the blowing of the airflow, and are completely crushed.

[0082] The second pulverizing path is a mixed feed layer, which includes at least two combined nozzles 4 arranged circumferentially along the pulverizing chamber 1. It can also be said that a plurality of combined nozzles 4 arranged circumferentially along the pulverizing chamber 1 in the same height area form a second pulverizing path for mixing and spraying high-speed airflow and raw materials to be pulverized.

[0083] The combined nozzle 4 includes a nozzle body 41, on which a discharge channel and an air outlet channel are formed. The discharge channel forms a second material nozzle 42, and the air outlet channel forms a second airflow nozzle 43. The second material nozzle 42 is connected to the second feeding member to provide raw materials into the pulverizing chamber, and the second airflow nozzle 43 is used to be connected to the second air supply component to spray high-pressure and high-speed airflow. In this way, the combined nozzle 4 integrates a discharge port and an air outlet. At the same time, the second material nozzle 42 and the second airflow nozzle 43 are nested or close to each other. When nested, the second airflow nozzle 43 is located in the discharge channel, that is, in the spray chamber of the second material nozzle 42, or the second material nozzle 42 is located in the second airflow nozzle 43. When close to each other, the second airflow nozzle 43 is located beside the second material nozzle 42, and the two are close to each other in the direction close to the nozzle. When nested, the axes of the second airflow nozzle 43 and the second material nozzle 42 can be parallel or coincident, or have an angle. When they are close to each other, the axes of the second airflow nozzle 43 and the second material nozzle 42 have a clamp, and the ejected airflow and the raw material gradually approach each other. On the same pulverizing path, the axis extension lines of all the second airflow nozzles 43 on each combined nozzle 4 converge to the same point, so that airflows in different directions collide at the convergence point.

[0084] When the second airflow nozzle 43 ejects high-speed high-pressure airflow, the high-speed moving airflow will drive the air flow around it. In this way, the high-speed high-pressure airflow ejected by the second airflow nozzle 43 will form a suction area at its nozzle 433, which can absorb and entrain the raw materials provided by the second material nozzle 42, and move the raw materials forward at high speed, giving the raw materials kinetic energy, so that the raw materials are significantly accelerated and moved at high speed, ejected out, and significantly increased the speed of the raw materials entering the crushing chamber 1. When the combined nozzles 4 in different directions eject airflow and raw materials, the raw materials in different directions will collide violently at the convergence point, thereby significantly enhancing the impact force between the raw materials, making the collision between the raw materials more intense, and can quickly and powerfully crush the raw materials, thereby improving the crushing effect. In this way, due to the structural characteristics of the combined nozzle 4, the raw materials are ejected, which increases the initial speed of the raw materials entering the crushing chamber 1, causing the incoming materials in different directions to collide more violently and more strongly, thereby improving the crushing effect. Compared with the first crushing path, the second crushing path has a stronger crushing force, and can also achieve a good crushing effect when crushing materials with greater hardness, and it takes less time and is more efficient.

[0085] At the same time, in the height direction, the raw materials entering from the pulverizing path at a lower position, after being pulverized, will be subjected to the impact of the airflow nozzle at a higher position and will hit more violently again in the process of moving upward and approaching the material outlet 101. Compared with the raw materials entering the pulverizing chamber 1 from the pulverizing path at a higher position, they will be subjected to stronger and more impacts and have a greater pulverizing force. That is, the pulverizing path at a lower position has a greater pulverizing force than the pulverizing path at a higher position, which can cause more and stronger impacts on the raw materials. Then, in the height direction of the pulverizing chamber 1, multiple layers of pulverizing paths with different pulverizing forces can be formed, and raw materials of different hardness can select the corresponding level of pulverizing path for pulverization according to the hardness level.

[0086] The first crushing path and / or the second crushing path are arranged on the crushing chamber 1. Therefore, the multiple crushing paths with different strengths on the crushing chamber 1 have various formation situations, which may be formed by multiple first crushing paths arranged in the height direction, or by multiple second crushing paths arranged in the height direction, or by at least one first crushing path and at least one second crushing path.

[0087] For example, in some embodiments, only a first crushing path is provided on the crushing chamber 1, and the first crushing path is provided with at least two layers, which are arranged along the height direction of the crushing chamber 1. Then, along the height direction, from top to bottom, the crushing force of each first crushing path gradually increases, and it can be used to crush raw materials of various different hardness levels.

[0088] In some embodiments, only the second pulverizing path is provided on the pulverizing chamber 1, and the second pulverizing path is provided with at least two layers and arranged along the height direction of the pulverizing chamber 1. Then, along the height direction, from top to bottom, the pulverizing force of each second pulverizing path gradually increases, forming a plurality of pulverizing paths with different pulverizing forces, which can be used to pulverize raw materials of various hardness levels.

[0089] In some embodiments, when both the first crushing path and the second crushing path have only one layer, the second crushing path can be set below the first crushing path. Then, the raw materials entering from the second crushing path will be impacted by the first airflow nozzle 3 when approaching the material outlet 101, and a more violent collision will occur again, resulting in a better crushing effect.

[0090] In some other embodiments, the first crushing path is provided with at least two layers, and the second crushing path may also be provided with at least two layers, and each crushing path is arranged in sequence in the height direction, and each second crushing path is located below all the first crushing paths. In this way, each crushing path arranged from high to low has a crushing force that gradually increases from low to high. When crushing a variety of raw materials with different hardness ranges, each raw material is grouped according to the hardness level, and then the raw materials of each component are arranged according to the hardness level and added to the appropriate crushing path. For example, the hardest raw material group is added to the lowest second crushing path, and the raw material group with the smallest hardness is added to the highest first crushing path.

[0091] Then, the multi-material crusher 11 can crush materials of different hardness in the same batch. The higher crushing path, such as the first crushing path at the higher position, is used to crush materials with smaller hardness, while the lower first crushing path, or the lower second crushing path formed by the combination nozzle 4, is used to crush materials with larger hardness. Moreover, since the combination nozzle 4 can accelerate the ejection of the raw materials and violently collide with them, the crushing effect of the raw materials is improved. It can not only be used to crush raw materials with larger hardness, but also shorten the crushing time of raw materials with larger hardness, and the crushing requirements of materials with large hardness can be quickly met. Therefore, when the crusher crushes raw materials with different hardness in the same batch, multiple raw materials with different hardness can be quickly and well crushed and mixed in the same crushing chamber 1, and the time taken to reach the preset crushing size is basically the same. They can be discharged from the multi-material crusher 11 through the material outlet 101 in the initial mixed state and enter the air flow mixer 20 for upgraded mixing, which significantly improves the crushing and mixing efficiency of multiple raw materials.

[0092] Of course, in addition to the arrangement position, the crushing strength of the second crushing path can also be adjusted by adjusting the airflow injection speed, injection amount, etc. of each layer of airflow nozzles. For example, on the combination nozzle 4 in the second crushing path, the number and angle of the second airflow nozzles 43 relative to the second material nozzles 42 will make the second crushing path of this layer have different crushing strengths, so that the second crushing paths of each layer on the multi-material crusher 11 can have different crushing strengths, and they are controllable and adjustable. They can be used to quickly crush a variety of raw materials of different hardness in the same batch according to needs, and to perform initial mixing of the raw materials to enhance the electrochemical properties of the final positive electrode material.

[0093] For example, in some embodiments, in the combined nozzle 4, on the nozzle body 41, the second airflow nozzle 43 and the second material nozzle 42 are nested, and the second airflow nozzle 43 may be nested with the second material nozzle 42, that is, nested outside the second material nozzle 42, or the second material nozzle 42 may be nested outside the second airflow nozzle. In this way, a second material nozzle 42 and a second airflow nozzle 43 are integrated on a combined nozzle 4, and when spraying, the raw material can be accelerated, and the crushing force is greater than that of the first crushing path.

[0094] In some embodiments, in the combined nozzle 4, on the nozzle body 41, the second air flow nozzle 43 and the second material nozzle 42 are close to each other. Figure 4 and Figure 5 As shown, the second airflow nozzle 43 is nested on the nozzle body 41 and is located beside the second material nozzle 42 (i.e., the discharge channel on the nozzle body 41). At the same time, from the air inlet end to the jet end of the second airflow nozzle 43, that is, the direction gradually approaching the nozzle opening 433, the second airflow nozzle 43 gradually approaches the axis of the second material nozzle 42, that is, it is inclined in the direction gradually approaching the axis of the second material nozzle 42. It can also be said that the distance from the air inlet end of the second airflow nozzle 43 to the axis of the second material nozzle 42 is greater than the distance from the nozzle opening 433 of the second airflow nozzle 43 to the axis of the second material nozzle 42. The flow path of the high-speed airflow ejected from the second airflow nozzle 43 is inclined relative to the axis of the second material nozzle 42 (which is also the incoming direction and original moving path of the raw material with higher hardness). On the one hand, compared with the parallel axis of the two, the suction acceleration area formed by the high-speed airflow is increased, so that more raw materials with higher hardness can be adsorbed, and the acceleration path and time of the raw materials with higher hardness can be extended, and more kinetic energy can be given to the raw materials with higher hardness, so that the collision between them is more intense, and the crushing effect is enhanced; on the other hand, the high-speed airflow ejected from the second airflow nozzle 43 gathers toward the central axis direction of the second material nozzle 42, so that it will not blow away but gather the raw materials with higher hardness, so that more raw materials with higher hardness gather and are ejected into the crushing chamber 1 after acceleration, and collide strongly with the raw materials with higher hardness ejected from the combined nozzle 4 in other directions; thereby, the crushing effect and crushing efficiency of the raw materials with higher hardness are improved from the aspects of enhancing the moving speed, impact degree and adsorption and gathering effect of the raw materials with higher hardness, so that the raw materials with higher hardness can be crushed in the same batch with the materials with lower hardness. The second crushing path composed of the combined nozzle 4 in this embodiment also has a higher crushing force.

[0095] Further, when the second airflow nozzle 43 is located beside the second material nozzle 42, its nozzle 433 can be aligned with the discharge port of the second material nozzle 42, or can exceed the discharge port of the second material nozzle 42 and be located outside the discharge port of the second material nozzle 42. Taking the implementation structure shown in the accompanying drawings, the nozzle 433 of the second airflow nozzle 43 exceeds the discharge port of the second material nozzle 42 and is located outside the second material nozzle 42 as an example for explanation, the suction acceleration area formed by the high-speed airflow at the nozzle 433 is partially located inside the second material nozzle 42, and partially located outside the second material nozzle 42, that is, inside the crushing chamber 1. It can not only accelerate the incoming material in the second material nozzle 42, but also absorb and accelerate the material that is already in the crushing chamber 1, that is, the material that has already collided for the first time, so as to increase the probability of secondary collision of this part of the material, thereby also enhancing the material crushing effect and the crushing strength of the crushing path.

[0096] On the other hand, one or more second airflow nozzles 43 may be provided on the same combined nozzle 4 (multiple means two or more). When at least two second airflow nozzles 43 are provided, the number of second airflow nozzles 43 increases, the acceleration area formed increases, and more hard raw materials provided by the second material nozzle 42 can be adsorbed and accelerated, thereby increasing the crushing force. When at least two second airflow nozzles 43 are provided, they can be arranged side by side, relatively, or around the second material nozzle 42. Among them, a plurality of second airflow nozzles 43 surrounding the second material nozzle 42 has a greater crushing force.

[0097] For example, at least two second air flow nozzles 43 are arranged on the nozzle body 41 along the circumference of the discharge channel, i.e., the second material nozzle 42. Figure 4 As shown in the accompanying drawings, three second air flow nozzles 43 are arranged around the central axis of the second material nozzle 42, and each nozzle 433 is close to the central axis of the second material nozzle 42. The central space enclosed by each second air flow nozzle 43 coincides with the axial direction of the second material nozzle 42 and the discharge direction. After each nozzle 433 ejects a high-speed airflow, the high-speed airflows gradually gather together, and a strong negative pressure area will be formed in the discharge direction of the second material nozzle 42. This negative pressure area coincides with the flow path of the raw material with higher hardness. The raw material with higher hardness, such as near the nozzle 433 in the second material nozzle 42, will be strongly adsorbed due to the negative pressure formed by the aggregation and wrapping of multiple high-speed airflows, and will be significantly accelerated forward and ejected at high speed, as shown in FIG. Figure 6As shown by the middle arrow. With such a configuration, the combined nozzle 4 can not only absorb more raw materials with higher hardness, accelerate more raw materials with higher hardness, and achieve a stronger acceleration effect, but also because all the nozzles 433 face the same direction, the absorbed raw materials with higher hardness will gather together, so that the acceleration and gathering effects of the raw materials are further improved. Compared with the acceleration of a single second airflow nozzle 43, the impact force of the raw materials with higher hardness can be further increased, thereby further improving the crushing force.

[0098] In a preferred embodiment, the second air flow nozzles 43 arranged around the central axis of the second material nozzle 42 have their axis extension lines converged at the axis or the axis extension line of the second material nozzle 42. Figure 6 As shown. Moreover, the axis extension lines of each combined nozzle 4 in the same pulverizing path also converge to the same point, that is, in the same pulverizing path, the axes of each second material nozzle 42 and each second airflow nozzle 43 converge to the same point. In this way, the gathering effect of raw materials with higher hardness is better, the movement is smoother, it is more conducive to speeding up, and the impact force is greater, and the pulverizing force is greater.

[0099] It can be known from the above structural embodiment of the combined nozzle 4 that the crushing strength can be controlled by adjusting the number and arrangement of the second airflow nozzles 43 on the combined nozzle 4, so that different second crushing paths have increasing crushing strength. The factors affecting the crushing strength of the second crushing path include, in addition to the number and arrangement of the second airflow nozzles 43, the speed and angle of the airflow sprayed by the second airflow nozzles 43 on the combined nozzle 4.

[0100] First, the angle adjustment will be described.

[0101] In some embodiments, a discharge channel and multiple air outlet channels are provided on the nozzle body 41 of the combined nozzle 4. Each air outlet channel forms a second air flow nozzle 43. There are multiple combined nozzles 4, and the multiple combined nozzles 4 have multiple specifications. The angles between the air outlet channel and the discharge channel are different on the combined nozzles 4 of different specifications. In this way, the angle between the second air flow nozzle 43 and the second material nozzle 42 can be changed.

[0102] Alternatively, in some embodiments, the second air flow nozzle 43 and / or the nozzle body 41 can be replaced to adjust the included angle between the second air flow nozzle 43 and the second material nozzle 42 .

[0103] For example, the nozzle body 41 is provided with a discharge channel for forming the second material nozzle 42, and is connected to the mounting plate 44. Meanwhile, the second airflow nozzle 43 is a tube body or a cylinder body, and is connected to the nozzle body 41 or the mounting plate 44. The nozzle body 41 has a mounting hole for the second airflow nozzle 43 to be embedded. The second airflow nozzle 43 extends into the mounting hole and is connected to the nozzle body 41 or the mounting plate 44. The combined nozzle 4 is mounted on the inner wall of the pulverizing chamber 1 through the mounting plate 44.

[0104] Meanwhile, the second airflow nozzle 43 is detachably connected to the nozzle body 41 or the mounting plate 44, and the second airflow nozzle 43 is provided with a variety of specifications, and the second airflow nozzles 43 of different specifications have different inclination angles. When the second airflow nozzles 43 of different specifications are installed on the nozzle body 41 or the mounting plate 44, they will form angles of different degrees with the second material nozzle 42. In this way, the injection angle of the airflow relative to the axis of the second material nozzle 42 can be adjusted by replacing the second airflow nozzle 43.

[0105] Alternatively, the second air flow nozzle 43 is detachably connected to the nozzle body 41 or the mounting plate 44, and the nozzle body 41 is also detachably connected to the mounting plate 44. The nozzle body 41 is provided with various specifications, and the angle between the axis of the mounting hole on the nozzle body 41 of various specifications and the axis of the second material nozzle 42 gradually increases, showing an increasing change.

[0106] In this way, in the combined nozzle 4, by replacing the nozzle body 41 and / or the second airflow nozzle 43 of different specifications, the inclination angle of the second airflow nozzle 43 relative to the second material nozzle 42 can be adjusted. When crushing different types of raw materials with different hardness, the specifications of the combined nozzle 4 can be adjusted by replacing the nozzle body 41 or the second airflow nozzle 43 according to the needs, and the angle between the second airflow nozzle 43 and the second material nozzle 42 can be changed, and the angle of the injected airflow, the convergence point of each airflow, etc. can be changed, thereby changing the acceleration path length for the material transportation, changing the impact force between the raw materials, adjusting the crushing force, and achieving different crushing requirements.

[0107] It can be seen that the second crushing path provided in this embodiment has a combined nozzle 4 with different specifications. The inclination angle of the second air flow nozzle 43 relative to the second material nozzle 42 can be changed by replacing parts, so that the impact degree of high-hardness materials can be adjusted as needed to meet different crushing requirements.

[0108] When the inclination angle of the second air flow nozzle 43 relative to the second material nozzle 42 is changed by replacing the nozzle body 41, since the cost of the nozzle body 41, which is mainly used for feeding and fixing the second air flow nozzle 43, is lower than the cost of the second air flow nozzle 43 that needs to spray high-pressure and high-speed airflow, the angle between the second air flow nozzle 43 and the second material nozzle 42 can be changed by replacing the nozzle body 41, which can save costs.

[0109] The detachable connection between the nozzle body 41 and the mounting plate 44 may be a threaded connection, or a connection through a fastener, or a detachable connection structure such as a buckle structure. The detachable connection between the second airflow nozzle 43 and the nozzle body 41 may be a threaded connection, or a connection through a detachable connection structure such as a buckle structure. This arrangement facilitates separation of the nozzle body 41 and the second airflow nozzle 43, and replacement of the two as needed.

[0110] In addition to adjusting the angle between the second airflow nozzle 43 and the second material nozzle 42 by replacing the nozzle body 41, the number of second airflow nozzles 43 installed on the same nozzle body 41 can also be adjusted by replacing nozzle bodies 41 of different specifications. For example, the second airflow nozzle 43 is detachably connected to the nozzle body 41 or the mounting plate 44, and the nozzle body 41 is also detachably connected to the mounting plate 44, and the nozzle body 41 is provided with a variety of specifications, and the number of mounting holes on the nozzle bodies 41 of various specifications gradually increases, showing an incremental change. Then, by replacing nozzle bodies 41 of different specifications, the number of second airflow nozzles 43 on the same combined nozzle 4 can be adjusted, and the number of second airflow nozzles 43 matched with the same second material nozzle 42 can be adjusted. In this way, the crushing strength of the raw material can also be changed to meet different crushing requirements.

[0111] The regulation of the air flow spray speed is described below.

[0112] In some embodiments, the first airflow nozzle 3 and / or the second airflow nozzle 43 are tubes, and both are Rafael tubes, or in other words, the tube cavity structure is a Rafael tube structure. Figure 5 As shown, the lumen includes a wide diameter section 431 and a narrow diameter section 432, and the narrow diameter section 432 is located between the wide diameter section 431 and the nozzle 433, and its diameter is smaller than the diameter of the wide diameter section 431. The nozzle 433 is in an expanded shape, and its diameter is larger than the diameter of the narrow diameter section 432. With such a configuration, the high-pressure airflow provided by the air supply component can be further accelerated by reducing the diameter, and after reducing the diameter, the expansion and ejection can further increase the flow rate of the gas (the Rafael tube principle in the prior art). The first airflow nozzle 3 and / or the second airflow nozzle 43 having this structure (first reducing the diameter and then expanding the ejection structure) can also be called a Rafael nozzle.

[0113] Therefore, in this embodiment, by setting the first air flow nozzle 3 and / or the second air flow nozzle 43 as a Rafale nozzle, the structural characteristics are utilized to further increase the flow velocity of the air flow, increase the speed of the air flow injected into the crushing chamber 1, enhance the blowing effect on the raw material, and enhance the impact crushing effect of the raw material, thereby enhancing the crushing force of the crushing path.

[0114] It can be seen from the above embodiments that the crushing force of each crushing path is not only affected by the height position. By adjusting the structure of the combined nozzle 4, multiple second crushing paths can also have different crushing forces. The various crushing paths can be set on the entire multi-material crusher 11 according to needs to ensure efficient completion of multi-raw material crushing and ensure that raw materials with different hardness are crushed to the required particle size, so that different raw materials can be mixed more thoroughly and evenly, and the sintering reaction can be more complete, thereby improving the electrochemical properties of the resulting positive electrode material.

[0115] Of course, in other embodiments, the first gas crushing system 10 may also include multiple single-material gas crushers, and the crushing chamber of the single-material gas crusher is provided with the above-mentioned first crushing path or the above-mentioned second crushing path, and the material outlets 101 of the multiple single-material gas crushers are all connected to the feed port of the airflow mixer 20. In this way, each raw material can be crushed individually, or it can be crushed independently in groups in different gas crushers.

[0116] In some other embodiments, the first gas crushing system 10 may also include a gas crusher with multiple independent crushing chambers, each of which is provided with a first crushing path or a second crushing path, and the material outlets 101 of each crushing chamber converge into the same pipeline, such as an induced air duct, and are connected to the air flow mixer 20 through the induced air duct. In this way, each raw material is crushed separately in different crushing chambers, but can be mixed at the first level after the material is discharged and before entering the mixer.

[0117] Alternatively, the first gas crushing system 10 includes a plurality of single-material gas crushers, and a crushing chamber of the single-material gas crusher is provided with the first crushing path or the second crushing path. At the same time, the crushing chambers of the plurality of single-material gas crushers are interconnected, so that the raw materials can be crushed and mixed at the same time, which is equivalent to primary mixing, and then enter the induced draft duct for secondary mixing, and enter the air flow mixer 20 for tertiary mixing, thus forming a three-stage mixing.

[0118] In some other embodiments, the first gas crushing system 10 is a multi-stage gas crushing system, for example, comprising a plurality of multi-material crushers 11, and the plurality of multi-material crushers 11 are connected in sequence to form a multi-stage gas crusher, and each raw material is sequentially introduced into each multi-material crusher 11 for crushing, thereby realizing multi-stage crushing, and the crushing and mixing effects are better.

[0119] A specific manufacturing example is listed below.

[0120] Production Example 1

[0121] Sodium carbonate, iron oxide, nickel oxide, and manganese oxide are weighed in a molar ratio of 1.1:0.15:0.8:0.05 and added to different feed ports of a multi-material pulverizer (i.e., added through different pulverization paths). Among them, nickel oxide (Mohs hardness of 7.5) and ferric oxide (Mohs hardness of 6.5) are added to the second pulverization path of the multi-material pulverizer to increase the number of collisions, while manganese dioxide (Mohs hardness of 5) and sodium carbonate (Mohs hardness of 4) are added to the first pulverization path, and the speed of the grading wheel is set to 15000rpm. After crushing, the raw materials that have been preliminarily mixed are introduced into the air flow mixer through the material outlet 101, and the air source pressure of the air flow mixer is adjusted to 0.8MPa, the pulse interval is 5s, and the mixing time is 5min. The mixed raw materials are received at the outlet of the air flow mixer and directly introduced into the box furnace. After sintering at 700 degrees for 20 hours, sodium-containing oxides are obtained, and the sodium-containing oxides are introduced into the gas crusher of the second gas crushing system, and the layered oxide-type sodium positive electrode material is obtained after crushing. The particle size of the positive electrode material is between 1-5 μm.

[0122] Production Example 2

[0123] Sodium carbonate, iron oxide, nickel oxide, and manganese oxide are weighed in a molar ratio of 1.1:0.15:0.8:0.05 and added to four independent single-material gas crushers. The material outlets 101 of the four single-material gas crushers converge into a total outlet. The total outlet is connected to the feed port of the air flow mixer through an induced draft duct. In this way, the crushed raw materials are added to the air flow mixer. The subsequent steps and program settings, sintering time, sintering temperature, etc. are the same as those in Example 1.

[0124] Production Example 3

[0125] Sodium carbonate, nickel oxide, and manganese oxide were weighed in a molar ratio of 1.1:0.8:0.2 and added to different feed ports of a multi-material pulverizer. Nickel oxide was added to the lower feed port of the multi-material pulverizer, i.e., the second pulverization path, and sodium carbonate and manganese oxide were added to the upper feed port, i.e., the first pulverization path. The subsequent steps and program settings, sintering time, sintering temperature, and other settings were the same as those in Example 1.

[0126] Production Example 4

[0127] Sodium carbonate and iron oxide were weighed in a molar ratio of 1.1:1 and added to different feed ports of a multi-material pulverizer. Iron oxide was added to the lower feed port of the multi-material pulverizer, such as the second pulverization path, and sodium carbonate was added to the upper feed port, such as the first pulverization path. The subsequent steps and program settings, sintering time, sintering temperature and other settings were the same as those in Example 1.

[0128] Production Example 5

[0129] Sodium carbonate, iron oxide, nickel oxide, manganese oxide, copper oxide, and zinc oxide are weighed in a molar ratio of 1.1:0.3:0.3:0.3:0.1:0.01 and added to different feed ports of a multi-material pulverizer. Sodium carbonate, copper oxide, zinc oxide, and manganese oxide are added to the upper feed port as the first pulverization path, and iron oxide and nickel oxide are added to the lower feed port as the second pulverization path. The subsequent steps and program settings, sintering time, sintering temperature, and other settings are the same as those in Example 1.

[0130] The performance comparison of three groups of embodiments is carried out below.

[0131] Test Example 1

[0132] Preparation of positive electrode material: The positive electrode material was prepared according to the above-mentioned Preparation Example 1, and the obtained positive electrode material was recorded as Product 1.

[0133] Preparation of electrodes: Product 1 was mixed with polyvinylidene fluoride and conductive carbon black in a ratio of 8:1:1; a certain amount of N-methylpyrrolidone solvent was added, and the resulting mixture was fully stirred using a mechanical centrifugal mixer to obtain a slurry. The slurry was evenly coated on aluminum foil using a coating machine, and then placed in a 100°C oven and vacuum dried for 12 hours. Subsequently, the dried electrode was cut into a circular electrode with a diameter of 12 mm, weighed, and the mass of active material on the circular electrode was calculated to be approximately 5 mg.

[0134] Electrochemical performance test: All battery assemblies were completed in a glove box (water and oxygen values ​​were all below 0.01ppm). Constant current charge and discharge tests and long cycle tests of button cells were performed using the Xinwei CT4008 charge and discharge tester, with a test voltage window of 2-4.2V.

[0135] Comparative Example 1

[0136] Preparation of positive electrode material: The same raw materials as those in comparative example 1 were used, but gas crushing was not performed, and only an air flow mixer was used to mix the raw materials. The other subsequent steps and settings such as mixing time, sintering time, and sintering temperature were the same as those in preparation example 1. The final product was recorded as product 2.

[0137] Preparation of electrode: Product 2 is mixed with polyvinylidene fluoride and conductive carbon black. The mixing ratio and other preparation contents are the same as those in Test Example 1.

[0138] Electrochemical performance test: same as test example 1.

[0139] Comparative Example 2

[0140] Preparation of positive electrode materials: Use the wet granulation method in the prior art to mix and dry the raw materials to obtain a sintered precursor. The specific wet granulation process is as follows: Sodium carbonate, iron oxide, nickel oxide, and manganese oxide are weighed in a molar ratio of 1.1:0.15:0.8:0.05 and dispersed in pure water, and the solid content is 20%. The above mixture is cyclically sand-milled in a sand mill for 90 minutes to obtain a stable and evenly dispersed slurry. The slurry is pumped into a spray dryer, and the inlet temperature is controlled at 250°C, the outlet temperature at 100°C, and the feed rate at 300mL / min to obtain a dry sintered precursor. The subsequent steps and program settings, sintering time, sintering temperature, etc. are the same as those in Example 1.

[0141] Preparation of electrode: Product 3 is mixed with polyvinylidene fluoride and conductive carbon black. The mixing ratio and other preparation contents are the same as those in Test Example 1.

[0142] Electrochemical performance test: same as test example 1.

[0143] The XRD spectra of product 1 in test example 1 and product 2 in comparative example 1 are compared, as shown in Figure 8. It can be proved that product 1 of test example 1 meets the characteristic peaks of O3-type layered sodium positive electrode materials. However, product 2 of comparative example 1 (having the same raw materials and sintering process as test example 1) not only shows the characteristic peaks of O3-type layered sodium positive electrode materials, but also shows the characteristic peaks of NiO, indicating that in comparative example 1, NiO in the raw materials did not completely migrate to the interior of the crystal lattice of product 2. The fusion rate of the elements in the raw materials is low, and the performance of product 2 is low.

[0144] Therefore, it can also be proved that in the present application, the first gas crushing system is used to gas crush each raw material and control the crushing particle size, which can improve the thoroughness of mixing of each raw material, enhance the sufficiency of the sintering reaction of each raw material, and improve the performance of the final product, i.e. the prepared positive electrode material.

[0145] The charge and discharge test results of the batteries in Test Example 1, Comparative Example 1 and Comparative Example 2 are compared. Fig. 9 At a discharge rate of 1C, product 1 has a specific capacity of more than 95.34 mAh / g (specific capacity refers to the discharge capacity per gram of product 1). After 80 charge and discharge cycles, the specific capacity of product 1 is 81.56 mAh / g, and the cycle capacity retention rate is as high as 85.5%. Its performance is significantly higher than that of the active materials in comparative examples 1 and 2.

[0146] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

Claims

1. A method for preparing a positive electrode material for a sodium ion battery, characterized in that: The following steps are included: Weighing raw materials according to a preset molar ratio, wherein the raw materials include a sodium source and one or more compound raw materials containing transition metal elements; Grouping the raw materials according to their hardness levels into components of different hardness levels; The raw materials of each component are added to the same pulverizing system through different pulverizing paths to achieve pulverization and mixing, wherein the different pulverizing paths have different pulverizing strengths, and the raw materials of each component are added to the pulverizing path with a pulverizing strength level adapted thereto according to the hardness level; Using a first gas crushing system to crush each raw material into a preset particle size; The raw materials gas-crushed by the first gas-crushing system are introduced into the air flow mixer by using the same air induced duct, so that the gas-crushed raw materials are mixed in the air induced duct at the primary level and mixed in the air flow mixer at the secondary level to obtain mixed raw materials; Using a sintering system to sinter the mixed raw materials in a gas environment to obtain a sodium-containing oxide; The sodium-containing oxide is crushed and sieved using a second gas crushing system to obtain the desired layered oxide-type sodium positive electrode material.

2. The method for preparing the positive electrode material for a sodium ion battery according to claim 1, characterized in that: Also includes: The airflow discharged in each of the above steps is subjected to dust removal treatment, and the purified airflow after the dust removal treatment is used as a circulating air source for recycling.

3. The method for preparing the positive electrode material for a sodium ion battery according to claim 1, characterized in that: It also includes: using a heat exchange system to recover heat from the tail gas discharged from the sintering system, and using the recovered heat to heat the circulating gas source used for crushing materials.

4. The method for preparing the positive electrode material for a sodium ion battery according to claim 1, characterized in that: The compound raw material comprises an iron source, a manganese source, a nickel source and a doping element, wherein the molar ratio of the sodium source, the iron source, the manganese source, the nickel source and the doping element is 1-1.1:0.2-0.9:0.05-0.9:0.1-0.9:0-0.1; wherein the molar ratio of the sodium source to the compound raw material is 1-1.1:

1.

5. The method for preparing the positive electrode material for a sodium ion battery according to claim 4, characterized in that: The sodium source is one or more of sodium carbonate, sodium dihydrogen phosphate, sodium sulfate, sodium nitrate, sodium hydroxide, sodium acetate, and sodium oxalate; the manganese source is one or more of manganese dioxide, manganese tetraoxide, manganese trioxide, manganese oxalate, manganese sulfate, manganese carbonate, and manganese nitrate; the nickel source is one or more of nickel sulfate, nickel nitrate, nickel oxide, and nickel hydroxide; the iron source is ferric oxide, ferric sulfate, ferric hydroxide, and ferrous oxide; the doping element is one or more of copper, titanium, magnesium, vanadium, niobium, lithium, aluminum, tungsten, molybdenum, chromium, silicon, strontium, zirconium, boron, zinc, and calcium.

6. The method for preparing the positive electrode material for a sodium ion battery according to claim 1, characterized in that: When the mixed raw materials are sintered in a gas environment using a sintering system, the sintering temperature is 500~1200℃ and the sintering time is 8~24h; Alternatively, when the mixed raw materials are sintered in a gas environment using a sintering system, a first sintering is performed at a temperature of 600-1100° C. for 2-12 hours; and then a second sintering is performed at a temperature of 500-900° C. for 2-12 hours.

7. The method for preparing the positive electrode material for a sodium ion battery according to claim 1, characterized in that: The first gas crushing system includes at least one multi-material crusher or a plurality of single-material gas crushers, and the multi-material crusher is provided with at least two layers of crushing paths arranged along the height direction of the crushing chamber.

8. A system for producing positive electrode materials for sodium ion batteries, characterized in that: A method for preparing a sodium ion battery positive electrode material according to any one of claims 1 to 7, comprising: A first gas crushing system, comprising a crushing chamber and a crushing path for materials and airflow to enter the crushing chamber, for crushing raw materials; An air flow mixer is connected to the material outlet of the first gas crushing system through an air induced duct to mix the crushed raw materials; A sintering system, including a primary sintering device and / or a secondary sintering device, for receiving the mixed raw materials discharged from the air flow mixer and sintering the mixed raw materials; A second gas crushing system, used for crushing and screening the product of the sintering system; The first gas crushing system comprises a multi-material crusher, wherein a crushing chamber of the multi-material crusher is provided with a material outlet, a classifying wheel, and a first crushing path and / or a second crushing path; The first pulverizing path includes a feed layer and an air intake layer, the feed layer includes at least one first material nozzle, the air intake layer includes at least two first air flow nozzles arranged along the circumference of the pulverizing chamber, the first material nozzle and the first air flow nozzle are separately arranged, and the first material nozzle is higher than the first air flow nozzle; The second pulverizing path is a mixed feed layer, which is provided with at least one layer in the height direction and includes at least two combined nozzles arranged along the circumference of the pulverizing chamber, and a second air flow nozzle and a second material nozzle are formed on the nozzle body of the combined nozzle, wherein the second material nozzle and the second air flow nozzle are nested; at least two second air flow nozzles are provided on the same combined nozzle, and at least two second air flow nozzles are arranged along the circumference of the second material nozzle and arranged around the second material nozzle, and the extended lines of the axes of the second air flow nozzles converge to the same point; The classifying wheel is located in the pulverizing chamber and is arranged at the material outlet, so that the material particles can be ejected through the material outlet after reaching a preset size.

9. The sodium ion battery positive electrode material production system according to claim 8, characterized in that: Also includes: A first dust removal system, wherein the exhaust gas inlet is connected to the exhaust ports of the first gas pulverizing system and the air flow mixer respectively, and the clean gas outlet is connected to the air inlet of the first gas pulverizing system; A second dust removal system, wherein the exhaust gas inlet is connected to the exhaust port of the second gas pulverizing system, and the clean gas outlet is connected to the air inlet of the second gas pulverizing system; The heat exchange system comprises a heat recovery pipeline for absorbing the heat of the exhaust gas from the sintering system, a first heat supply pipeline for supplying heat to the first gas crushing system, and a second heat supply pipeline for supplying heat to the second gas crushing system.

10. The sodium ion battery positive electrode material production system according to claim 8, characterized in that: In the height direction of the pulverizing chamber, the material outlet is opened at the top, the first pulverizing path and / or the second pulverizing path are provided with at least two layers, and each of the second pulverizing paths is located below all of the first pulverizing paths.

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