Nickel-iron-manganese precursor and preparation method, positive electrode material and preparation method and equipment

Abstract

The present invention provides a nickel-iron-manganese precursor and a preparation method, a positive electrode material and a preparation method and equipment. The preparation method of the nickel-iron-manganese precursor comprises dissolving a nickel-iron-manganese metal salt in deionized water to obtain a mixed metal salt solution, introducing the metal salt solution, a precipitant, and a complexing agent into a reactor at the same time for a coprecipitation reaction to obtain a slurry, washing and dehydrating the slurry, and placing it in a heating container with an adjustable vacuum degree for heat treatment to obtain a nickel-iron-manganese precursor. The present invention washes and dehydrates the composite hydroxide slurry obtained by the coprecipitation of nickel-iron-manganese, and then places it in a heating container with an adjustable vacuum degree for treatment to obtain a large-specific nickel-iron-manganese oxide precursor, which is used to prepare a sodium-ion battery positive electrode material with the advantages of low free sodium, excellent electrical properties, and high production capacity.

Description

Technical Field

[0001] The present invention relates to the technical field of positive electrode materials for sodium ion batteries, and in particular to a nickel-iron-manganese precursor and a preparation method thereof, a positive electrode material and a preparation method and equipment thereof. Background Art

[0002] Sodium-ion batteries have advantages in resources, cost, and safety. They are highly competitive, have broad application prospects, and have huge market potential. The performance of sodium-ion batteries mainly depends on the positive electrode material. Currently, there are three technical routes for positive electrode materials for sodium-ion batteries on the market: the layered metal oxide series, the polyanion series, and the Prussian blue series. Among them, layered transition metal oxides have a higher specific capacity, and they have many similarities with the more mature lithium battery positive electrode materials on the market in terms of synthesis and production line design. They are currently the most widely used positive electrode materials for sodium-ion batteries.

[0003] Although sodium-embedded layered transition metal oxides have high energy density, the layered transition metal oxides currently on the market basically have poor air stability and high free sodium. First, it will cause harsh processing conditions, second, it is easy to cause battery bloating, and third, it affects the battery cycle performance. At present, one of the methods in the industry to reduce the residual alkali on the surface of sodium-embedded layered transition metal oxides is to pass volatile acidic gases into the material to react with the residual alkali on the surface of the material, but acidic gases are easy to corrode equipment and have high requirements for equipment materials; the second is to wash the material with water to reduce the residual alkali on the surface, but it will cause excessive precipitation of sodium ions in the lattice, resulting in structural changes and decreased performance; and the performance of sodium-embedded layered transition metal oxides mainly depends on the precursor. At present, the conventional sodium-ion battery positive electrode material precursor has a small specific surface area and low reaction activity, which has an adverse effect on the synthesis of sodium-ion battery positive electrode materials. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a nickel-iron-manganese precursor, which solves the problem of small specific surface area of ​​the positive electrode material precursor in the prior art.

[0005] According to an embodiment of the present invention, a nickel-iron-manganese precursor is provided, which includes a coexistence of NixFeyMn(1-xy)(OH)2 and NixFeyMn(1-xy)O, wherein 0.2≤x≤0.3, 0.3≤y≤0.4.

[0006] According to an embodiment of the present invention, a positive electrode material is also provided. The positive electrode material is prepared using the nickel-iron-manganese precursor and has a chemical formula of NazNixFeyMn(1-xy), wherein 0.2≤x≤0.3, 0.3≤y≤0.4, and 0.67≤z≤1.1.

[0007] According to an embodiment of the present invention, a method for preparing the above-mentioned nickel-iron-manganese precursor is also provided, wherein a nickel-iron-manganese metal salt is dissolved in deionized water to obtain a mixed metal salt solution, the metal salt solution, a precipitant, and a complexing agent are simultaneously introduced into a reactor for a coprecipitation reaction to obtain a slurry, and the slurry is washed and dehydrated and then placed in a heating container with an adjustable vacuum degree for heat treatment to obtain a nickel-iron-manganese precursor; wherein the heat treatment temperature is 400-450°C, the vacuum degree is -190--150Pa, and the time is 4-6h; wherein the washing target is S≤1000ppm, Na + ≤400ppm.

[0008] Furthermore, the precipitant is sodium hydroxide solution, the complexing agent is ammonia solution, the concentration of the nickel-iron-manganese metal salt is 1.5-2.5 mol / L, the concentration of the precipitant is 6-10 mol / L, and the concentration of the complexing agent is 5-7 mol / L.

[0009] Further, the coprecipitation reaction comprises:

[0010] The first stage: nucleation, control the system pH at 11.10-11.50, ammonia concentration 2-6g / L, and nucleation time at 5-10h;

[0011] The second stage: growth, control the system pH at 10.10-10.4, ammonia concentration 2-6g / L, growth time 60-150h. When the reactor liquid reaches the overflow port of the concentrator, it is necessary to start the self-circulation between the concentrator and the reactor, and start the clearing to increase the solid content of the reactor, and continue the reaction until the product particle size reaches the target particle size.

[0012] According to an embodiment of the present invention, a method for preparing the above-mentioned positive electrode material is also provided. The nickel-iron-manganese precursor and the sodium source are evenly mixed and then calcined. The calcination temperature is 920°C and the calcination time is 12 hours. After calcination, it is cooled to room temperature and crushed and pulverized to obtain a positive electrode material with a particle size of 3-5.5μm.

[0013] According to an embodiment of the present invention, there is also provided a device for the above-mentioned method for preparing the positive electrode material, which is used for crushing, comprising:

[0014] A crushing box, wherein the upper end of the crushing box is fixedly connected to a feed hopper, the lower end of the crushing box is fixedly connected to a discharge hopper, and a crushing roller group is also arranged in the crushing box;

[0015] A material guide plate, both ends of which extend obliquely downward in opposite directions and are separated from the inner wall of the feed hopper. A pair of guide rods are vertically fixedly arranged in the feed hopper, and a pair of cross bars are transversely vibrated. An expansion hole for the two guide rods to pass through is provided at the highest point in the middle section of the material guide plate, and the lower parts of both ends of the material guide plate overlap the two cross bars respectively;

[0016] A dust reduction component, the dust reduction component includes an air blowing pipe fixedly connected in the feed hopper and located below the two guide rods, an air inlet pipe fixedly connected to the feed hopper and communicating with the air blowing pipe, and a first air outlet pipe fixedly connected to the feed hopper and communicating with a portion of the feed hopper located above the guide plate, wherein the air blowing pipe is connected to a plurality of air blowing nozzles.

[0017] Furthermore, it also includes an arc plate fixedly connected to the feed hopper and located below the material guide plate, and the arc opening of the arc plate faces the crushing box, and the air blowing pipe is located between the material guide plate and the arc plate.

[0018] Furthermore, the dust reduction assembly also includes an air duct fixedly connected to the feed hopper and located below the arc plate, and a second air outlet pipe fixedly connected to the feed hopper and communicating with the air duct, wherein the air duct is provided with an air inlet nozzle.

[0019] Furthermore, an annular cavity is provided in the wall of the feed hopper, the first air outlet pipe is connected to the annular cavity, and a plurality of connecting holes are provided on the inner wall of the feed hopper.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The obtained nickel-iron-manganese precursor has a higher specific surface area and a higher reaction activity, which is beneficial to the synthesis of positive electrode materials for sodium ion batteries and suitable for continuous production. The prepared positive electrode materials for sodium ion batteries not only have low free sodium and excellent electrical properties, but also significantly improved production capacity. At the same time, a method for preparing the nickel-iron-manganese precursor and the positive electrode material, as well as equipment for crushing the positive electrode material are provided. The equipment can efficiently crush the material (i.e., the calcined material) and then carry out the next step of pulverization, which is beneficial to improving the overall operating efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the SEM test result of the precursor of Example 1;

[0023] Figure 2 This is the SEM test result of the precursor of Example 2;

[0024] Figure 3 This is the SEM test result of the precursor of Example 3;

[0025] Figure 4 This is the SEM test result of the precursor of Comparative Example 1;

[0026] Figure 5 This is the SEM test result of the positive electrode material of Experimental Example 1;

[0027] Figure 6This is the charge and discharge curve of the positive electrode material of Experimental Example 1;

[0028] Figure 7 This is a cycle curve diagram of the positive electrode material of Experimental Example 1;

[0029] Figure 8 This is the SEM test result of the positive electrode material of Experimental Example 2;

[0030] Fig. 9 This is the charge and discharge curve of the positive electrode material of Experimental Example 2;

[0031] Fig.10 This is a cycle curve diagram of the positive electrode material of Experimental Example 2;

[0032] Fig.11 is a structural schematic diagram of another embodiment;

[0033] Fig.12 for Fig.11 A schematic diagram of the enlarged local structure at center A;

[0034] Fig.13 for Fig.11 A magnified schematic diagram of the local structure at B in the middle;

[0035] In the above drawings:

[0036] Crushing box 1, feed hopper 2, discharge hopper 3, guide plate 4, guide rod 5, cross bar 6, expansion hole 7, air blowing pipe 8, air inlet pipe 9, first air outlet pipe 10, air blowing nozzle 11, crushing roller 12, elastic ring 13, annular cavity 14, connecting hole 15, guide hopper 16, ring plate 17, fixing plate 18, spring 19, connecting ring 20, baffle plate 21, arc plate 22, air guide pipe 23, second air outlet pipe 24, air inlet nozzle 25, arc-shaped depression 26, thickening portion 27. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0038] The present embodiment provides a nickel-iron-manganese precursor, the precursor includes a coexistence of the chemical formula NixFeyMn(1-xy)(OH)2 and NixFeyMn(1-xy)O, wherein 0.2≤x≤0.3, 0.3≤y≤0.4. The preparation method is as follows: dissolving nickel-iron-manganese metal salt in deionized water to obtain a mixed metal salt solution, introducing the metal salt solution, a precipitant, and a complexing agent into a reactor at the same time for coprecipitation reaction to obtain a slurry, washing and dehydrating the slurry and placing it in a heating container with adjustable vacuum for heat treatment to obtain a nickel-iron-manganese precursor; wherein the heat treatment temperature is 400-450°C, the vacuum degree is -190—-150Pa, and the time is 4-6h, wherein the precipitant includes a sodium hydroxide solution, the complexing agent includes an ammonia solution, and the pulverization uses an air flow pulverizer.

[0039] In exemplary embodiment 1,

[0040] Nickel sulfate, ferrous sulfate and manganous sulfate crystals are added to deionized water in a Ni:Fe:Mn molar ratio of 0.2:0.3:0.5 to prepare a 1.5 mol / L metal salt solution, and the metal salt solution is protected by nitrogen to prevent oxidation of the metal solution; deionized water is added to a 60L reactor and the internal stirring blade is turned on to rotate at a constant speed of 430r / min, the reactor is heated to 50°C and nitrogen is passed in for protection, the prepared ammonia solution is added to prepare the bottom liquid ammonia concentration to 3.5g / L, the prepared sodium hydroxide solution is added to adjust the bottom liquid pH to 11.10, the ammonia solution is supplemented to the bottom liquid ammonia concentration of 5g / L, and the preparation of the bottom liquid is completed.

[0041] Start the nucleation stage, keep the temperature in the kettle at 50°C, and introduce the above-prepared metal salt solution, 6 mol / L sodium hydroxide solution and ammonia solution into the reactor at the same time. The metal liquid flow rate is 1.5 L / h, and the flow rates of sodium hydroxide and ammonia solutions are adjusted to maintain the pH value of 11.10 and the ammonia concentration of 5 g / L. React under this condition for 5 hours to complete the nucleation step.

[0042] Start the growth phase, gradually lower the pH of the reactor to 10.1, adjust the metal liquid flow rate to 2L / h, and continue the reaction for 60h until the product particle size reaches 3.0um.

[0043] In the post-treatment stage, the slurry after the reaction is washed with hot diluted alkali with a mass fraction of 5% and a temperature of 70°C until S ≤ 1000ppm, and then washed with pure water at a temperature of 70°C until Na + ≤400ppm, centrifugally dehydrated and placed in a vacuum oven (heatable vacuum drying oven HE-WD-400, the same below), adjusted the vacuum degree to -150Pa, the temperature to 450℃, the time to 4h, taken out and passed through a 400-mesh sieve to obtain a nickel-iron-manganese precursor, the scanning electron microscope of which is as follows Figure 1 shown.

[0044] In exemplary embodiment 2,

[0045] The difference between this embodiment and embodiment 1 is that the vacuum degree and heating temperature of the vacuum oven are different, and the embodiment specifically includes the following steps:

[0046] Nickel sulfate, ferrous sulfate and manganous sulfate crystals are added to deionized water in a Ni:Fe:Mn molar ratio of 0.22:0.34:0.44 to prepare a 2 mol / L metal salt solution, and the metal salt solution is protected by nitrogen to prevent oxidation of the metal solution; deionized water is added to a 60L reactor and the internal stirring blade is turned on to rotate at a constant speed of 450r / min, the reactor is heated to 55°C and nitrogen is passed in for protection, the prepared ammonia solution is added to prepare the bottom liquid ammonia concentration to 4.5g / L, the prepared sodium hydroxide solution is added to adjust the bottom liquid pH to 11.30, the ammonia solution is supplemented to the bottom liquid ammonia concentration of 6g / L, and the preparation of the bottom liquid is completed.

[0047] Start the nucleation stage, keep the temperature in the kettle at 55°C, and simultaneously introduce the above-prepared metal salt solution, 8 mol / L sodium hydroxide solution and ammonia solution into the reactor for reaction. The metal liquid flow rate is 1.5 L / h, and the flow rates of sodium hydroxide and ammonia solutions are adjusted to maintain the pH value of 11.30 and the ammonia concentration of 6 g / L. React under this condition for 7 hours to complete the nucleation step.

[0048] Start the growth phase, gradually lower the pH of the reactor to 10.2, adjust the metal liquid flow rate to 2L / h, and continue the reaction for 100h until the product particle size reaches 3um.

[0049] In the post-treatment stage, the slurry after the reaction is washed with hot diluted alkali with a mass fraction of 5% and a temperature of 70°C until S ≤ 1000ppm, and then washed with pure water at a temperature of 70°C until Na + ≤400ppm, centrifugally dehydrated and placed in a vacuum oven, the vacuum degree was adjusted to -170Pa, the temperature was 420℃, the time was 5h, and the nickel-iron-manganese precursor was obtained by passing through a 400-mesh sieve. The scanning electron microscope showed Figure 2 shown.

[0050] In exemplary embodiment 3,

[0051] The difference between this embodiment and embodiment 2 is that the vacuum degree and heating temperature of the vacuum oven are different, and the embodiment specifically includes the following steps:

[0052] Nickel sulfate, ferrous sulfate and manganous sulfate crystals were added to deionized water in a Ni:Fe:Mn molar ratio of 0.3:0.4:0.3 to prepare a 2.5 mol / L metal salt solution. The metal salt solution was protected by nitrogen to prevent oxidation of the metal solution. Deionized water was added to a 60L reactor and the internal stirring blade was turned on to rotate at a constant speed of 470r / min. The reactor was heated to 60°C and nitrogen was passed in for protection. The prepared ammonia solution was added to prepare the bottom liquid ammonia concentration to 5.5 g / L, the prepared sodium hydroxide solution was added to adjust the bottom liquid pH to 11.50, and the ammonia solution was supplemented to the bottom liquid ammonia concentration of 7 g / L to complete the preparation of the bottom liquid.

[0053] Start the nucleation stage, keep the temperature in the kettle at 60°C, and simultaneously introduce the above-prepared metal salt solution, 10 mol / L sodium hydroxide solution and ammonia solution into the reactor for reaction. The metal liquid flow rate is 1.5 L / h, and the flow rates of sodium hydroxide and ammonia solutions are adjusted to maintain the pH value of 11.50 and the ammonia concentration of 7 g / L. React under this condition for 10 hours to complete the nucleation step.

[0054] Start the growth phase, gradually lower the pH of the reactor to 10.4, adjust the metal liquid flow rate to 2L / h, and continue the reaction for 150 minutes until the product particle size reaches 3um.

[0055] In the post-treatment stage, the slurry after the reaction is washed with hot diluted alkali with a mass fraction of 5% and a temperature of 70°C until S ≤ 1000ppm, and then washed with pure water at a temperature of 70°C until Na + ≤400ppm, centrifugally dehydrated and placed in a vacuum oven, the vacuum degree was adjusted to -190Pa, the temperature was 400℃, the time was 6h, and the nickel-iron-manganese precursor was obtained by passing through a 400-mesh sieve. The scanning electron microscope showed Figure 3 shown.

[0056] Comparative Example 1

[0057] This comparative example provides a method for preparing a nickel-iron-manganese precursor. In this comparative example, the slurry is washed, centrifuged, and then dried at low temperature, which specifically includes the following steps:

[0058] Nickel sulfate, ferrous sulfate and manganous sulfate crystals are added to deionized water in a Ni:Fe:Mn molar ratio of 0.22:0.34:0.44 to prepare a 2 mol / L metal salt solution, and the metal salt solution is protected by nitrogen to prevent oxidation of the metal solution; deionized water is added to a 60L reactor and the internal stirring blade is turned on to rotate at a constant speed of 450r / min, the reactor is heated to 55°C and nitrogen is passed in for protection, the prepared ammonia solution is added to prepare the bottom liquid ammonia concentration to 4.5g / L, the prepared sodium hydroxide solution is added to adjust the bottom liquid pH to 11.30, the ammonia solution is supplemented to the bottom liquid ammonia concentration of 6g / L, and the preparation of the bottom liquid is completed.

[0059] Start the nucleation stage, keep the temperature in the kettle at 55°C, and simultaneously introduce the above-prepared metal salt solution, 8 mol / L sodium hydroxide solution and ammonia solution into the reactor for reaction. The metal liquid flow rate is 1.5 L / h, and the flow rates of sodium hydroxide and ammonia solutions are adjusted to maintain the pH value of 11.30 and the ammonia concentration of 6 g / L. React under this condition for 7 hours to complete the nucleation step.

[0060] Start the growth phase, gradually lower the pH of the reactor to 10.2, adjust the metal liquid flow rate to 2L / h, and continue the reaction for 100h until the product particle size reaches 3um.

[0061] Post-treatment: The slurry after the reaction is discharged into an aging tank, and the target nickel-iron-manganese precursor is obtained through aging, centrifugation, water washing, drying, screening and demagnetization. Figure 4 shown.

[0062] The specific surface areas of the precursors obtained in Examples 1-3 and Comparative Example 1 and commercially available nickel-iron-manganese precursors are shown in the following table:

[0063]

[0064] Combined with Figure 1-4 As shown in the table above, the specific surface area of ​​the precursor of the present invention is much larger than that of conventional nickel-iron-manganese precursors in the same industry. The present invention obtains a nickel-iron-manganese precursor with a large specific surface area by washing and dehydrating the slurry of nickel-iron-manganese co-precipitation and then heat treating it under a certain vacuum environment. The post-treatment selection of vacuum heat treatment has the following advantages: vacuum heating is conducive to the volatilization of part of the hydrogen and oxygen in the lattice in the form of water vapor and leaving a large number of gaps in the lattice, thereby increasing the specific surface area and improving the reaction activity.

[0065] In a further embodiment, a positive electrode material is provided, the chemical formula of which is NazNixFeyMn(1-xy), wherein 0.2≤x≤0.3, 0.3≤y≤0.4, and 0.67≤z≤1.1. The preparation method thereof is as follows: the nickel iron manganese precursor is uniformly mixed with a sodium source and then calcined at a calcination temperature of 920°C for 12 hours, and then cooled to room temperature after calcination, and crushed and pulverized to obtain a positive electrode material with a particle size of 3-5.5 μm.

[0066] In the exemplary experimental example 1,

[0067] The nickel-iron-manganese precursor prepared in the above Example 1 was made into a positive electrode material. The specific steps were as follows: sodium carbonate and the precursor obtained in Example 1 were fully mixed in a high-speed mixer, calcined at 920° C. for 12 h, crushed, graded and sieved to obtain a sodium ion battery positive electrode material with a particle size of 3-5.5 μm. SEM showed Figure 5 The prepared positive electrode material was tested for electrochemical performance at a voltage of 2.0-4.0V (0.1C charge-discharge curve and 50 cycles of 1C discharge cycle diagram), and the results are as follows Figure 6 and 7 As shown, the 0.1C discharge capacity is 140mAh / g, and the 50-cycle 1C cycle retention rate reaches 92%.

[0068] Experimental Example 2

[0069] The nickel-iron-manganese precursor prepared in Comparative Example 1 was made into a positive electrode material, and the specific steps were as follows: sodium carbonate and the precursor obtained in Comparative Example 1 were fully mixed in a high-speed mixer, calcined at 920° C. for 12 h, crushed, graded and sieved to obtain a positive electrode material for a sodium ion battery, and SEM showed that Figure 8 The prepared positive electrode material was tested for electrochemical performance at a voltage of 2.0-4.0V (0.1C charge-discharge curve and 50 cycles of 1C discharge cycle diagram), and the results are as follows Fig. 9 and 10 As shown, the 0.1C discharge capacity is 120mAh / g, and the 50-cycle 1C cycle retention rate is 85%.

[0070] Experimental Example 1, Experimental Example 2 and commercially available nickel-iron-manganese-based sodium battery were compared in terms of pH, residual alkali and 0.1c discharge specific capacity. The data are shown in the following table:

[0071]

[0072] Experimental Example 1 and Experimental Example 2 are different only in the precursors. The experimental data show that the sodium ion positive electrode material made from the nickel-iron-manganese precursor of the present invention has low free sodium and excellent electrical properties.

[0073] In a further embodiment, Fig.11 , 12 As shown, a device for preparing the positive electrode material obtained in Experimental Example 1 is provided,

[0074] For crushing, including:

[0075] A crushing box 1, wherein the upper end of the crushing box 1 is fixedly connected to a feed hopper 2, and the lower end is fixedly connected to a discharge hopper 3, and a crushing roller group is also arranged in the crushing box 1;

[0076] A pair of guide plates 4, both ends of which extend obliquely downward in opposite directions and are separated from the inner wall of the feed hopper 2. A pair of guide rods 5 are vertically fixedly arranged in the feed hopper 2, and a pair of cross bars 6 are vibrated horizontally. An expansion hole 7 for the two guide rods 5 to pass through is opened at the highest point in the middle section of the guide plate 4, and the lower parts of the two ends of the guide plate 4 are overlapped with the two cross bars 6 respectively;

[0077] A dust reduction component includes an air blowing pipe 8 fixedly connected to the feed hopper 2 and located below the two guide rods 5, an air inlet pipe 9 fixedly connected to the feed hopper 2 and communicating with the air blowing pipe 8, and a first air outlet pipe 10 fixedly connected to the feed hopper 2 and communicating with a portion of the feed hopper 2 located above the guide plate 4, wherein the air blowing pipe 8 is connected to a plurality of air blowing nozzles 11.

[0078] When the device is used, the calcined material is put into the feed hopper 2. As the material is put into the feed hopper 2, the material falls and contacts the guide plate 4, and slides down along the guide plate 4, through the gap between the end of the guide plate 4 and the feed hopper 2, and falls into the crushing box 1 below. The crushing roller group in the crushing box 1 may include a pair of meshing crushing rollers 12. The fallen material is crushed between the two crushing rollers 12, and then falls to the bottom and is discharged through the discharge hopper 3. During the crushing process, due to the operation of the crushing rollers 12, the material crushing may cause fragments to splash. In this embodiment, a roof-shaped guide plate 4 is arranged in the feed hopper 2 to prevent the fragments from flying out. At the same time, the cross bar 6 is provided with a pair of mounting holes for the cross bar 6 to be installed on the external driving member (such as a vibration motor). An elastic ring 13 (such as a rubber ring) is arranged between the mounting hole and the cross bar 6. The material guide plate 4 overlapped with the material guide plate 4 can vibrate, and when the material falls on the material guide plate 4, it can slide down more efficiently without causing stagnation; more preferably, a dust reduction component is also provided, which is connected to the external air source through the air inlet pipe 9, and introduces cold air into the air inlet pipe 9, and then enters the air blowing pipe 8, and then enters the feed hopper 2 through the air blowing nozzle 11, thereby providing a cold source in the feed hopper 2 to further cool the material. Furthermore, a first air outlet pipe 10 is also provided on the outside, which can cooperate with the air blowing pipe 8 to guide the airflow in the feed hopper 2, so that the airflow is discharged through the first air outlet pipe 10, and at the same time, it can also take away the dust generated in the crushing process, thereby playing a dust reduction role.

[0079] In a further exemplary embodiment, Fig.11 As shown, an annular cavity 14 is further provided in the wall of the feed hopper 2, the first air outlet pipe 10 is connected to the annular cavity 14, and a plurality of connecting holes 15 are further provided on the inner wall of the feed hopper 2. These through holes are arranged in a surrounding manner, which is equivalent to forming an annular channel (i.e., the annular cavity 14 and the plurality of connecting holes 15) in the upper end of the feed hopper 2. The airflow through the connecting holes 15 can enter the annular channel more efficiently and then be guided away by the first air outlet pipe 10. Furthermore, in this embodiment, a fixed A guide hopper 16 is fixedly connected therein, the upper end of the guide hopper 16 is open and larger, and the lower end is also open and smaller. A ring plate 17 is fixedly connected between the lower end of the guide hopper 16 and the inner wall of the feed hopper 2. The ring plate 17 is located above all the connecting holes 15, and the material enters the feed hopper 2 through the guide hopper 16. The ring plate 17 and the guide hopper 16 further prevent the airflow from directly overflowing upward, thereby more effectively preventing dust from overflowing, and does not affect the normal continuous feeding, which is beneficial to the subsequent continuous processing operation.

[0080] In a further exemplary embodiment, Fig.11 , 12As shown, a fixing plate 18 is fixedly connected in the feed hopper 2, and two guide rods 5 are vertically fixed on the fixing plate 18. The fixing plate 18 provides a mounting base for the guide rods 5. Two springs 19 respectively surrounding the corresponding guide rods 5 are also fixedly connected to the fixing plate 18. The upper ends of the two springs 19 are fixedly connected to the guide plate 4 respectively. The guide rods 5 provide up and down guidance for the guide plate 4, and the diameter of the expanded hole 7 is larger than the outer diameter of the guide rods 5, so that the guide plate 4 can avoid violent collision with the guide rods 5 during vibration, and the springs 19 provide up and down buffering for the guide plate 4; further, on the guide plate 4, Two connecting rings 20 are also fixedly connected and surround the corresponding guide rods 5. The upper end of the spring 19 is fixedly connected to the corresponding connecting ring 20, and the connecting ring 20 provides a direct connection basis for the spring 19; further, a baffle plate 21 is fixedly connected between the upper ends of the two guide rods 5. The baffle plate 21 is located above the guide plate 4 and its top surface is arc-shaped. The baffle plate 21 provides a barrier for the guide plate 4 at the top to prevent the guide plate 4 from detaching from the guide rod 5 from above, and the arc-shaped setting can prevent the material from staying there. Furthermore, the set expansion hole 7 is completely covered by the baffle plate 21, which can prevent the material from falling into the expansion hole 7.

[0081] In a further exemplary embodiment, Fig.11 , 12 As shown in 13, the components such as the cross bar 6, the guide rod 5 and the spring 19 provide a supporting basis for the guide plate 4. When the cross bar 6 vibrates, the guide plate 4 also vibrates, thereby improving the feeding efficiency. An arc-shaped recess 26 is also provided on the guide plate 4 to accommodate the corresponding part of the cross bar 6, so that when the cross bar 6 vibrates, it can enter or exit the arc-shaped recess 26 with a gap, which is equivalent to making the positional relationship between the cross bar 6 and the guide plate 4 relatively fixed through the arc-shaped recess 26, so that the guide plate 4 will not swing greatly and cause jamming when facing a greater impact.

[0082] In a further exemplary embodiment, Fig.13 As shown, both sides of the arc-shaped recess 26 can be thickened to form a thickened portion 27 to expand the space for the cross bar 6 to be accommodated. At the same time, the mechanical strength of the location is enhanced by the thickened portion 27, and the thickened portion 27 (the thickened portions on both sides) is used to form relative upper and lower limit stops on the cross bar 6, thereby helping to improve the vibration stability of the guide plate 4.

[0083] In a further exemplary embodiment, Fig.11 , 12As shown, the equipment also includes an arc plate 22 fixedly connected to the feed hopper 2 and located below the guide plate 4, and the arc opening of the arc plate 22 faces the crushing box 1, and the air blowing pipe 8 is located between the guide plate 4 and the arc plate 22. Gaps are also provided between the two ends of the arc plate 22 and the feed hopper 2 for smooth passage of materials. The fragments generated during the crushing process will be first blocked by the arc plate 22, thereby avoiding adverse effects on components such as the spring 19 and the air blowing nozzle 11.

[0084] In a further exemplary embodiment, Fig.11 , 12 As shown, the dust reduction component also includes an air duct 23 fixedly connected to the feed hopper 2 and located below the arc plate 22, and a second air outlet pipe 24 fixedly connected to the feed hopper 2 and communicating with the air duct 23, wherein the air duct 23 is provided with an air inlet nozzle 25, and the end of the second air outlet pipe 24 can be connected to an exhaust fan, so that the airflow in the feed hopper 2 enters the air duct 23 through the air inlet nozzle 25, and then is guided away through the second air outlet pipe 24 (similarly, an exhaust fan can also be provided at the end of the first air outlet pipe 10), so that the generated dust can be more efficiently extracted to the outside, and at the same time, part of the cold air can also be guided to flow downward and finally enter the air duct 23 and then outward, so that in cooperation with the first air outlet pipe 10, the upper and lower parts of the feed hopper 2 can be assisted in cooling, and dust can be guided out at the same time, and the overall processing efficiency can be further improved.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a positive electrode material, characterized in that: The nickel iron manganese precursor and the sodium source are mixed evenly and then calcined at a temperature of 920°C for 12 hours. After calcination, the mixture is cooled to room temperature and crushed to obtain a positive electrode material with a particle size of 3-5.5 μm. The nickel iron manganese precursor includes Ni x Fe y Mn （1-x-y） (OH)2 and Ni x Fe y Mn （1-x-y） O coexistence, where 0.2≤x≤0.3, 0.3≤y≤0.4; The preparation method of the nickel-iron-manganese precursor comprises: dissolving a nickel-iron-manganese metal salt in deionized water to obtain a mixed metal salt solution, introducing the metal salt solution, a precipitant, and a complexing agent into a reactor at the same time for a coprecipitation reaction to obtain a slurry, washing and dehydrating the slurry, and placing the slurry in a heating container with an adjustable vacuum degree for heat treatment to obtain a nickel-iron-manganese precursor; wherein the heat treatment temperature is 400-450°C, the vacuum degree is -190--150Pa, and the time is 4-6h; wherein the washing target is S≤1000ppm, Na + ≤400ppm.

2. The preparation method according to claim 1, characterized in that The precipitant includes sodium hydroxide solution, the complexing agent is an ammonia solution, the concentration of the nickel-iron-manganese metal salt is 1.5-2.5 mol / L, the concentration of the precipitant is 6-10 mol / L, and the concentration of the complexing agent is 5-7 mol / L.

3. The preparation method according to claim 2, characterized in that: The coprecipitation reaction comprises: The first stage: nucleation, control the system pH at 11.10-11.50, ammonia concentration 2-6g / L, and nucleation time at 5-10h; The second stage: growth, control the system pH at 10.10-10.4, ammonia concentration 2-6g / L, growth time 60-150h. When the reactor liquid reaches the overflow port of the concentrator, it is necessary to start the self-circulation between the concentrator and the reactor, and start the clearing to increase the solid content of the reactor, and continue the reaction until the product particle size reaches the target particle size.

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