A sodium-ion battery cathode material carbonate precursor and a preparation method thereof

Abstract

This invention provides a carbonate precursor for sodium-ion battery cathode materials and its preparation method. The preparation method includes: weighing G salt to prepare a first solution; weighing J salt to prepare a second solution; weighing M salt to prepare a third solution; preparing a complexing agent solution; preparing a mixed solution of Ni, Fe, and Mn metal salts, adding an antioxidant to form the base liquid of the first reaction system; adding the complexing agent and antioxidant to a reaction vessel to form the base liquid of the second reaction system; adding the second solution, the third solution, and the complexing agent solution to the base liquid of the second reaction system; simultaneously adding the first solution to the first reaction system and adding the solution of the first reaction system to the second reaction system for a co-precipitation reaction to form gradient doping of G metal elements; and obtaining the precursor after the reaction is completed. This invention achieves uniform multi-element doping through in-situ elemental doping during the precursor preparation process, resulting in good doping effect and gradient doping of G metal salts.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion batteries, and more specifically to a carbonate precursor for sodium-ion battery cathode materials and its preparation method. Background Technology

[0002] Driven by the global energy transition and carbon neutrality strategy, sodium-ion batteries have attracted much attention as an emerging rechargeable battery technology. In recent years, with the shortage of lithium resources, rising costs, and increasing environmental protection demands, sodium-ion batteries have become an important supplement and even a potential alternative to lithium-ion battery systems due to their significant advantages such as abundant resources, low cost, and high safety.

[0003] Layered oxide cathode materials exhibit high energy density and rapid charge-discharge potential in sodium-ion batteries, but their insufficient structural stability has become a key bottleneck restricting their industrial application. During sodium-ion insertion / extraction, the layered structure is prone to irreversible lattice distortion, leading to a continuous decline in cycle capacity. Specifically, the O3-type crystal structure easily transforms into the low-sodium-content P3 phase under high sodium deintercalation conditions, resulting in an irreversible reduction in active sites. Elemental doping to regulate crystal field stability is an effective strategy to improve the structural integrity of materials, but traditional high-temperature solid-state sintering methods fail to achieve the expected modification effect due to the uneven spatial distribution of doping elements and low lattice occupancy efficiency. Therefore, developing novel uniform doping processes to achieve precise doping at the atomic scale has become a key path to improve the electrochemical performance of layered cathode materials. It should be noted that single-element doping systems can only produce limited optimization of specific material properties, while multi-element synergistic doping strategies based on precursor design can not only overcome the performance optimization bottleneck of single-element doping but also achieve a comprehensive improvement in the overall material performance through synergistic regulation of electronic effects between elements. Summary of the Invention

[0004] This invention proposes an innovative design for the preparation of carbonate precursors for sodium-ion battery cathode materials, aiming to balance the high stability of the layered oxide structure with improved battery electrochemical performance. The prepared cathode material uses Ni... x Fe y Mn z G t J u M vThis CO3 multi-element composite system possesses dual characteristics: atomic-level precise doping of multiple elements in specific proportions and gradient doping of gibbsite metal (G). The gradient doping of G involves gradually adding a first solution containing G salts to the base solution of a first reaction system containing Ni, Fe, and Mn metal salts (forming the first reaction system), while simultaneously gradually flowing the base solution of the first reaction system containing G into a reactor containing the base solution of a second reaction system, resulting in gradient doping of G in the reactor (forming the second reaction system). By constructing a synergistic mechanism between the two reaction systems, and precisely controlling parameters such as pH, temperature, and time in both the first and second reaction systems, metal ions are directionally deposited in the solution to form a stable carbonate precursor with atomically uniform dispersion. After cleaning and drying, the precursor and sodium source material are uniformly and thoroughly mixed, and then synthesized using a solid-state high-temperature calcination process in an oxygen atmosphere, ultimately obtaining a nickel-iron-manganese-based layered oxide cathode material uniformly doped with multiple metal elements. This material achieves a dual breakthrough in improving the stability of layered oxide cathode materials and optimizing ion transport channels through the synergistic regulation of the electronic effects of multiple metal ions and gradient structure design.

[0005] This invention provides a method for preparing a carbonate precursor for a sodium-ion battery cathode material, comprising the following steps: according to the precursor chemical formula Ni x Fe y Mn z G t J u M v For CO3 preparation, weigh out salt G, dissolve it in an acidic solution to prepare a first solution, wherein G is at least one of Y, Mg, Zn, and Al, J is at least one of Zr and Ti, M is at least one of W, Mo, and Ta, 0.33≤x≤1, 0≤y≤0.33, 0≤z≤0.33, 0.0005≤t≤0.05, 0.0005≤u≤0.05, 0.0005≤v≤0.05, and x+y+z+t+u+v=1; weigh out salt J, dissolve it in an acidic solution to prepare a second solution; weigh out salt M, dissolve it in a carbonate solution to prepare a third solution; mix deionized water with a complexing agent to prepare a complexing agent. Solution: Prepare a mixed solution of Ni, Fe, and Mn metal salts according to the general chemical formula of the precursor, and add an antioxidant to form the base liquid of the first reaction system; add a complexing agent and an antioxidant to the reactor, and introduce an inert gas into the reactor to form the base liquid of the second reaction system; add the second solution, the third solution, and the complexing agent solution to the base liquid of the second reaction system, and stir continuously; simultaneously add the first solution to the base liquid of the first reaction system, and introduce the base liquid of the first reaction system with the first solution added into the reactor to perform gradient doping of G metal element; after the reaction is completed, filter, wash, dry, sieve, and demagnetize the slurry in the reactor to obtain the carbonate precursor of sodium-ion battery cathode material. Furthermore, the concentration of salt G in the first solution is 0.1 mol / L to 4 mol / L, the concentration of salt J in the second solution is 0.001 mol / L to 10 mol / L, the concentration of salt M in the third solution is 0.001 mol / L to 10 mol / L, the concentration of carbonate solution is 0.2 mol / L to 10 mol / L, and the concentration of complexing agent solution is 0.1 mol / L to 5 mol / L.

[0006] Furthermore, the complexing agent used to prepare the complexing agent solution and the complexing agent added to the reaction vessel to form the bottom liquid of the second reaction system are at least one of ammonia, EDTA and 5-sulfosalicylic acid.

[0007] Furthermore, the antioxidants forming the base liquid of the first reaction system and the base liquid of the second reaction system are at least one of ascorbic acid, citric acid and ethylenediaminetetraacetic acid.

[0008] Furthermore, the temperature at which the M salt dissolves in the carbonate solution is 35℃~85℃; the M salt is at least one of sodium tantalate, potassium tantalate, sodium molybdate, potassium molybdate, sodium tungstate, and potassium tungstate.

[0009] Furthermore, the temperature at which salt J dissolves in acidic solution is 35℃~85℃, and the pH during the dissolution process is 1~7; salt J is at least one of zirconium nitrate, zirconium sulfate, zirconium acetate, and zirconium isopropoxide.

[0010] Furthermore, when the first solution is added to the base liquid of the first reaction system, the pH of the system can be controlled to be 8-10. When the base liquid of the first reaction system containing the first solution is introduced into the reaction vessel, the pH of the system can be controlled to be 10-12.

[0011] Furthermore, the temperature at which the first solution is added to the bottom liquid of the first reaction system is 35℃~85℃, the reaction time is 1h~15h, and the precipitation time is 1-10h; the temperature at which the bottom liquid of the first reaction system with the first solution is introduced into the reaction vessel is 35℃~85℃, the reaction time is 1h~15h, and the precipitation time is 1h~10h.

[0012] Furthermore, the rate at which the first solution is added to the base liquid of the first reaction system is the same as the rate at which the base liquid of the first reaction system is added to the reaction vessel; the acidic solution used to prepare the first solution and the second solution is at least one of dilute nitric acid, dilute hydrochloric acid, dilute sulfuric acid and acetic acid; the inert gas introduced into the reaction vessel is nitrogen, and the nitrogen introduction rate is 1L / min to 5L / min.

[0013] Another aspect of the present invention provides a sodium-ion battery cathode material carbonate precursor, which can be prepared by the sodium-ion battery cathode material carbonate precursor preparation method described above.

[0014] Another aspect of the present invention provides a sodium-ion battery cathode material, which can be prepared from the sodium-ion battery cathode material carbonate precursor described above.

[0015] Compared with the prior art, the beneficial effects of the present invention include at least one of the following: (2) The precursor preparation of the present invention adopts in-situ element doping to form a high-entropy precursor, realizing the uniform dispersion and uniform doping of multiple elements, improving the doping effect, and the doping effect is excellent.

[0016] (3) The method of the present invention optimizes the sodium ion insertion / extraction stress buffer and ion transport path through gradient doping, and forms a nanoscale composite interface, thereby improving air stability and interface reaction kinetics.

[0017] (2) Through the design of multi-element doping and partial element gradient doping, the precursor particle size is normally distributed, and the resulting layered cathode material has good electrochemical stability. It does not require additional modification, and the process is short and easy to operate. Attached Figure Description

[0018] The above and other objects and features of the present invention will become clearer from the following description taken in conjunction with the accompanying drawings, in which: Figure 1 This is a schematic diagram of the precursor preparation apparatus of the present invention.

[0019] Figure 2 The image shows the morphology and particle size distribution of the precursor prepared in Example 1.

[0020] Figure 3 The graph shows the cycling performance of the cathode material prepared in Example 2 at 1C.

[0021] Figure 4 The image shows the morphology and particle size distribution of the precursor prepared in Example 2.

[0022] Figure 5 The image shows the morphology and particle size distribution of the precursor prepared in Example 3.

[0023] Figure 6 The image shows the morphology and particle size distribution of the precursor prepared in Example 4.

[0024] Explanation of reference numerals in the attached figures: 1-First batching mechanism, 2-Second batching mechanism, 3-Third batching mechanism, 4-First metering pump, 5-Second metering pump, 6-Third metering pump, 7-Fourth metering pump, 8-Fifth metering pump, 9-Liquid storage tank, 10-First stirring system, 11-Second stirring system, 12-First reaction mechanism, 13-Second reaction mechanism, 14-First pH meter, 15-First gas storage tank, 16-Second pH meter, 17-Second gas storage tank. Detailed Implementation

[0025] In the following, a carbonate precursor for a sodium-ion battery cathode material and its preparation method according to the present invention will be described in detail with reference to the accompanying drawings and exemplary embodiments.

[0026] One aspect of the present invention provides a method for preparing a carbonate precursor for a sodium-ion battery cathode material, which may include the following steps: Step 1, according to the precursor chemical formula Ni x Fe y Mn z G t J u M v CO3 ingredients are prepared by weighing out salt G, dissolving it in an acidic solution to prepare a first solution, wherein G is at least one of Y, Mg, Zn and Al, J is at least one of Zr and Ti, M is at least one of W, Mo and Ta, 0.33≤x≤1, 0≤y≤0.33, 0≤z≤0.33, 0.0005≤t≤0.05, 0.0005≤u≤0.05, 0.0005≤v≤0.05, and x+y+z+t+u+v=1.

[0027] Step 2: Weigh out salt J, dissolve it in an acidic solution, and prepare a second solution.

[0028] Step 3: Weigh out salt M, dissolve it in carbonate solution, and prepare a third solution.

[0029] Step 4: Mix deionized water with the complexing agent to prepare a complexing agent solution.

[0030] Step 5: Prepare a mixed solution of Ni, Fe and Mn metal salts according to the general chemical formula of the precursors, and add an antioxidant to form the base liquid of the first reaction system.

[0031] Step 6: Add the complexing agent and antioxidant to the reaction vessel, and introduce an inert gas into the reaction vessel to form the bottom liquid of the second reaction system.

[0032] Step 7: Add the second solution, the third solution, and the complexing agent solution to the base liquid of the second reaction system and continue stirring.

[0033] Step 8: While adding the first solution to the bottom liquid of the first reaction system, the bottom liquid of the first reaction system with the added first solution is circulated into the reaction vessel to perform gradient doping of G metal elements.

[0034] Step 9: After the reaction is complete, filter, wash, dry, sieve, and demagnetize the slurry in the reactor to obtain the carbonate precursor for sodium-ion battery cathode material.

[0035] In some embodiments, the acidic solution used to prepare the first solution in step 1 can be at least one of dilute nitric acid, dilute hydrochloric acid, dilute sulfuric acid, and acetic acid.

[0036] In some embodiments, the acidic solution used to prepare the second solution in step 2 can be at least one of dilute nitric acid, dilute hydrochloric acid, dilute sulfuric acid, and acetic acid.

[0037] In some implementations, the carbonate in step 3 can be sodium carbonate.

[0038] In some embodiments, the complexing agent in step 4 can be one or more of ammonia, EDTA, and 5-sulfosalicylic acid. The concentration of the complexing agent solution can be from 0.1 mol / L to 5 mol / L. For example, the concentration of the complexing agent solution can be 0.5 mol / L to 4.6 mol / L, 1.2 mol / L to 4.1 mol / L, 1.8 mol / L to 3.5 mol / L, 2.1 mol / L to 3.2 mol / L, 2.5 mol / L to 2.8 mol / L, or a combination thereof.

[0039] In some implementations, the antioxidant in step 5 can be any one of ascorbic acid, citric acid, and ethylenediaminetetraacetic acid (EDTA).

[0040] In some embodiments, the complexing agent in step 6 can be one or more of ammonia, EDTA, and 5-sulfosalicylic acid. The antioxidant can be any one of ascorbic acid, citric acid, and ethylenediaminetetraacetic acid (EDTA).

[0041] In some implementations, step 8 involves forming a first reaction system by introducing a first solution into the base liquid of the first reaction system. Simultaneously, a peristaltic pump is used to pass the solution from the first reaction system into a reaction vessel containing a second solution, a third solution, a complexing agent solution, and the base liquid of the second reaction system to form a second reaction system. By constructing a dual reaction system with synergistic effects and controlling the reaction pH, temperature, and time, gradient doping of the G metal element is achieved, promoting the directional deposition of metal ions in the solution to form a stable carbonate precursor with atomically uniform dispersion. In the first reaction system, the G salt can be deposited on the surface of the Ni-Fe-Mn structure. Subsequently, the G salt is gradient doped over time and undergoes a co-precipitation reaction with the J and M salts in the second system, ultimately forming the carbonate precursor structure.

[0042] In some implementations, the temperature at which the first solution is added to the base liquid of the first reaction system can be 35℃~85℃, the reaction time can be 1h~15h, and the precipitation time can be 1h~10h. For example, the temperature at which the first solution is added to the base liquid of the first reaction system can be 38℃~75℃, the reaction time can be 3h~12h, and the precipitation time can be 3h~8h. Yet another example is that the temperature at which the first solution is added to the base liquid of the first reaction system can be 45℃~62℃, the reaction time can be 5h~8h, and the precipitation time can be 4h~7h.

[0043] In some embodiments, the temperature at which the base liquid of the first reaction system with the first solution is introduced into the reactor is 35°C to 85°C, the reaction time is 1 hour to 15 hours, and the sedimentation time can be 1 hour to 10 hours. For example, the temperature at which the base liquid of the first reaction system with the first solution is introduced into the reactor is 41°C to 80°C, the reaction time is 4 hours to 13 hours, and the sedimentation time can be 2 hours to 7 hours. Yet another example is that the temperature at which the base liquid of the first reaction system with the first solution is introduced into the reactor is 52°C to 63°C, the reaction time is 6 hours to 10 hours, and the sedimentation time can be 4 hours to 5 hours.

[0044] In some embodiments, the addition rate of the first solution to the base liquid of the first reaction system can be the same as the addition rate of the base liquid of the first reaction system containing the first solution to the reaction vessel. This same rate ensures that the first and second reaction systems proceed simultaneously, and that the G metal is uniformly dispersed in a gradient on the surface of the Ni-Fe-Mn metal oxide, enabling the metal oxide mixed solution of the G salt and the salt solution in the second reaction system to react together, forming a uniform carbonate precursor structure.

[0045] In some embodiments, when the first solution is added to the base liquid of the first reaction system, the pH of the system is controlled to be 8-10, that is, the pH of the first reaction system is controlled to be 8-10. For example, the pH of the first reaction system is controlled to be 9. When the base liquid of the first reaction system containing the first solution is introduced into the reaction vessel, the pH of the system is controlled to be 10-12, that is, the pH of the second reactant is controlled to be 10-12. For example, the pH of the second reaction system is controlled to be 11.

[0046] In some implementations, the concentration of salt J can be 0.001 mol / L to 10 mol / L, the concentration of salt M can be 0.001 mol / L to 10 mol / L, the concentration of the first solution can be 0.1 mol / L to 4 mol / L, and the concentration of the carbonate solution can be 0.2 mol / L to 10 mol / L. For example, the concentration of salt J can be 0.15 mol / L to 8.3 mol / L, the concentration of salt M can be 0.20 mol / L to 8.5 mol / L, the concentration of the first solution can be 0.5 mol / L to 3.2 mol / L, and the concentration of the carbonate solution can be 1.3 mol / L to 7.8 mol / L. As another example, the concentration of salt J can be 1.32 mol / L to 5.6 mol / L, the concentration of salt M can be 3.2 mol / L to 6.5 mol / L, the concentration of the first solution can be 2.1 mol / L to 2.8 mol / L, and the concentration of the carbonate solution can be 2.7 mol / L to 5.9 mol / L.

[0047] In some embodiments, the temperature at which salt M dissolves in the carbonate solution can be between 35°C and 85°C. For example, the temperature can be a combination of 38°C to 81°C, 43°C to 75°C, 51°C to 69°C, or higher. Salt M can be at least one of sodium tantalate, potassium tantalate, sodium molybdate, potassium molybdate, sodium tungstate, and potassium tungstate.

[0048] In some embodiments, the temperature at which salt J dissolves in the acidic solution can be 35°C to 85°C, and the pH during the dissolution process can be 1 to 7. For example, the temperature at which salt J dissolves in the acidic solution can be 40°C to 75°C, and the pH during the dissolution process can be 2 to 6. As another example, the temperature at which salt J dissolves in the acidic solution can be 48°C to 59°C, and the pH during the dissolution process can be 3 to 5. Salt J can be at least one of zirconium nitrate, zirconium sulfate, zirconium acetate, and zirconium isopropoxide.

[0049] In some embodiments, the acidic solutions used to prepare the first solution and the second solution may be at least one of dilute nitric acid, dilute hydrochloric acid, dilute sulfuric acid, and acetic acid.

[0050] In some embodiments, the inert gas introduced into the reactor can be nitrogen, and the nitrogen introduction rate can be from 1 L / min to 5 L / min. For example, the nitrogen introduction rate can be a combination of 2 L / min to 4.5 L / min, 2.5 L / min to 3.5 L / min, or higher.

[0051] In some implementations, the washing in step 9 can be done with deionized water. The drying temperature can be 120°C to 170°C. The sieve mesh size can be 400 ± 100 mesh.

[0052] In some embodiments, the base solution forming the first reaction system can be obtained by adding an antioxidant to a mixed solution of Ni, Fe, and Mn metal salts and then stirring uniformly at a stirring rate of 200 r / min to 500 r / min. The stirring rate for continuous stirring in step 7 can be 200 r / min to 500 r / min.

[0053] Another aspect of the present invention provides a sodium-ion battery cathode material carbonate precursor, which can be prepared by the sodium-ion battery cathode material carbonate precursor preparation method described above.

[0054] Another aspect of the present invention provides a sodium-ion battery cathode material, which can be prepared from the sodium-ion battery cathode material carbonate precursor described above. For example, the preparation method may include: A sodium-ion battery cathode material, consisting of a carbonate precursor and a sodium source material, is uniformly and thoroughly mixed, and then synthesized using a solid-state high-temperature calcination process in an oxygen atmosphere to obtain a layered oxide cathode material uniformly doped with multiple metal elements based on nickel, iron, and manganese. The high-temperature calcination temperature can be 600℃~900℃, and the calcination time can be 7℃~12℃.

[0055] To better understand the present invention, specific examples are provided below to further illustrate the content of the present invention, but the content of the present invention is not limited to the examples below.

[0056] The apparatus used in the embodiments of the present invention is as follows: Figure 1 As shown, it includes a first batching mechanism 1, a second batching mechanism 2, a third batching mechanism 3, a first metering pump 4, a second metering pump 5, a third metering pump 6, a fourth metering pump 7, a fifth metering pump 8, a liquid storage tank 9, a first stirring system 10, a second stirring system 11, a first reaction mechanism 12, a second reaction mechanism 13, a first pH meter 14, a first gas storage tank 15, a second pH meter 16, and a second gas storage tank 17.

[0057] The first mixing unit 1 is used to prepare the first solution and is connected to the first reaction unit 12 via the first metering pump 4. The second mixing unit 2 is used to prepare the second solution and is connected to the second reaction unit 13 via the second metering pump 5. The second reaction unit 13 can be a reaction vessel. The third mixing unit 3 is used to prepare the third solution and is connected to the second reaction unit 13 via the third metering pump 6. The storage tank 9 is used to store the complexing agent solution and is connected to the second reaction unit 13 via the fifth metering pump 8. The first stirring system 10 is installed in the first reaction unit 12 and is used to stir the reaction system in the first reaction unit. The second stirring system 11 is installed in the second reaction unit 13 and is used to stir the reaction system in the second reaction unit. The first reaction unit 12 and the second reaction unit 13 are connected via the fourth metering pump 7. The first pH meter 14 is used to measure the pH value in the first reaction unit 12. The second pH meter 16 is used to measure the pH value in the second reaction unit 13. The first gas storage tank 15 is used to introduce inert gas into the first reaction unit 12. The second gas storage tank 17 is used to introduce inert gas into the second reaction unit 13. The reaction within the first reaction mechanism 12 forms the first reaction system, and the reaction within the second reaction mechanism 13 forms the second reaction system.

[0058] Specifically, following the general chemical formula for precursor preparation, salt G is weighed and dissolved in an acidic solution in the first preparation unit 1 to prepare a first solution. This first solution is then added to the Ni, Fe, and Mn metal salt mixed solution system in the first reaction unit 12, with the flow rate controlled by the first metering pump 4. Salt J is weighed and dissolved in an acidic solution, and prepared as a second solution in the second preparation unit 2. Salt M is weighed and dissolved in a carbonate solution, and prepared as a third solution in the third preparation unit 3. The rate at which the first solution enters the Ni, Fe, and Mn metal salt mixed solution system is controlled to be the same as the rate at which the second and third solutions flow concurrently into the bottom liquid of the second reaction system in the second reaction unit 13. The reaction vessel in the second reaction unit 13 is equipped with a stirring system and a pH meter. A co-precipitation reaction is carried out by controlling the pH. After the reaction, the slurry is filtered, washed with water, and dried to obtain the sodium-ion battery carbonate precursor.

[0059] To better understand the present invention, specific examples are provided below to further illustrate the content of the present invention, but the content of the present invention is not limited to the examples below. Example

[0060] A method for preparing a carbonate precursor for a sodium-ion battery cathode material may include the following steps: Step 1: Weigh 41.455g of aluminum sulfate according to the molar ratio of metal ions (nickel, iron, manganese, aluminum, titanium, molybdenum) of 1:100 (i.e., aluminum:(nickel+iron+manganese+aluminum+titanium+molybdenum)=1:100), dissolve it in 0.02mol / L dilute sulfuric acid and stir well to prepare the first solution.

[0061] Step 2: Weigh titanium nitrate according to the stoichiometric ratio, wherein 35.879 g of titanium nitrate is weighed according to the molar ratio of metal ions (nickel, iron, manganese, aluminum, titanium, molybdenum) of 1:100, and dissolved in 0.02 mol / L dilute sulfuric acid to prepare a second solution.

[0062] Step 3: Weigh sodium carbonate and sodium molybdate. Weigh 24.970g of sodium molybdate according to a molar ratio of 1:100 for the metal ions (nickel, iron, manganese, aluminum, titanium, molybdenum). Dissolve sodium carbonate and sodium molybdate in deionized water to prepare a third solution with a sodium carbonate concentration of 0.5mol / L at a dissolution temperature of 30℃.

[0063] Step 4: Mix deionized water with the complexing agent to prepare a 0.5 mol / L complexing agent solution.

[0064] Step 5: Dissolve nickel sulfate, ferric sulfate, and manganese sulfate in deionized water at a ratio of 49:18:30, add 50g of antioxidant and stir well to prepare a 0.5mol / L first reaction system base solution.

[0065] Step 6: Add 0.5 mol / L ammonia water and 50 g ascorbic acid to a 10 L reactor, and continuously introduce nitrogen gas into the reactor at 1.5 L / min to prepare a 3 L second reaction system base liquid.

[0066] Step 7: Add the second solution, the third solution, and the ammonia solution to the second reaction base liquid in the reactor at a concurrent flow rate of 10 ml / min, and stir continuously at 500 r / min.

[0067] Step 8: The first solution, aluminum sulfate solution, is introduced into the first reaction system, Ni, Fe, Mn metal salt solution, at a rate of 10 ml / min and stirred at a rate of 500 r / min until homogeneous. At the same time, the first solution and the Ni, Fe, Mn metal salt mixture are pumped into the reaction vessel in step 7 at the same rate to ensure that the two reaction systems react simultaneously at the same rate. The pH of the first system is controlled at 3.5 and the pH of the second system is controlled at 8.5. The reaction is carried out continuously at 35°C for 40 hours. Then, the feeding is stopped and the mixture is aged for 8 hours to obtain the slurry.

[0068] Step 9: Collect the slurry, filter and wash it, dry the resulting filter cake in a 120℃ forced-air drying oven for 24 hours, and then sieve and demagnetize it to obtain the target carbonate structure precursor.

[0069] Step 10: The core-shell precursor obtained is mixed with sodium carbonate at a molar ratio of (Ni+Fe+Mn+Al+Ti+Mo):Na = 2:1. The mixture is placed in a tube furnace under an oxygen atmosphere and calcined at 950℃ for 12 hours. After cooling to room temperature, (Na2CO3)@(Ni) is obtained.0.4836 Fe 0.1878 Mn 0.2965 Al 0.0105 Ti 0.0103 Mo 0.0105 O2)2 cathode material.

[0070] ICP analysis of the dried precursor revealed Ni, Fe, Mn, Al, Ti, and Mo content at mass percentages of 24.17%, 8.92%, 13.85%, 0.24%, 0.42%, and 0.86%, respectively. Converted to relative molar ratios, the actual precursor was Ni. 0.4836 Fe 0.1878 Mn 0.2965 Al 0.0105 Ti 0.0103 Mo 0.0105 The relative molar ratios of various elements in the CO3 precursor basically conform to the set Ni. 0.49 Fe 0.18 Mn 0.30 Al 0.01 Ti 0.01 Mo 0.01 CO3 precursor target. The morphology and particle size distribution of the precursor are as follows. Figure 2 As shown. From Figure 2 It can be seen that the carbonate precursor for sodium-ion batteries is spherical, and the precursor particle size follows a normal distribution. Example

[0071] Step 1: Weigh 9.758g of zinc sulfate according to the molar ratio of metal ions (nickel, iron, manganese, zinc, zirconium, tantalum) of 1:100, dissolve it in dilute sulfuric acid and stir well to prepare the first solution.

[0072] Step 2: Weigh 17.152 g of zirconium sulfate according to the stoichiometric ratio, wherein the molar ratio of zirconium sulfate to metal ions (nickel, iron, manganese, zinc, zirconium, tantalum) is 1:100. Dissolve it in 0.01 mol / L dilute sulfuric acid to prepare a second solution.

[0073] Step 3: Weigh out sodium carbonate and sodium tantalate. Weigh out 15.273g of sodium tantalate according to a molar ratio of 1:100 for the metal ions (nickel, iron, manganese, zinc, zirconium, tantalum). Dissolve the sodium carbonate and sodium tantalate in deionized water to prepare a third solution with a sodium carbonate concentration of 1mol / L at a dissolution temperature of 45℃.

[0074] Step 4: Mix deionized water with the complexing agent to prepare a 0.5 mol / L complexing agent solution; Step 5: Dissolve nickel sulfate, ferric sulfate, and manganese sulfate in deionized water at a stoichiometric ratio of 60:17:20, add antioxidant and stir well to prepare a 1 mol / L first reaction system solution. Step 6: Add 0.5 mol / L ammonia water and 50 g ascorbic acid to a 10 L reactor, and continuously introduce nitrogen gas into the reactor at 1.5 L / min to prepare a 3 L second reaction system bottom liquid. Step 7: Add the second solution, the third solution, and the ammonia solution to the second reaction base liquid in the reactor at a concurrent flow rate of 10 ml / min, and stir continuously at 500 r / min.

[0075] Step 8: The first solution, zinc sulfate solution, is introduced into the first reaction system, Ni, Fe, Mn metal salt solution, at a rate of 10 ml / min. The mixture is stirred at 500 r / min until homogeneous. Simultaneously, the first solution and the Ni, Fe, Mn metal salt mixture are pumped into the reaction vessel in Step 7 at the same rate, ensuring that both reaction systems react simultaneously at the same rate. The pH of the first system is controlled at 3.5, and the pH of the second system is controlled at 8. The reaction is carried out continuously at 50°C for 24 hours. Then, feeding is stopped, and the mixture is aged for 12 hours to obtain the slurry.

[0076] Step 9: Collect the slurry, filter and wash it, dry the resulting filter cake in a 120℃ forced-air drying oven for 24 hours, and then sieve and demagnetize it to obtain the target precursor.

[0077] Step 10: The prepared core-shell precursor was mixed with sodium carbonate at a molar ratio of (Ni+Fe+Mn+Zn+Zr+Ta):Na = 2:1. The mixture was then calcined in a tube furnace under an oxygen atmosphere at 950°C for 12 hours. After cooling to room temperature, (Na2CO3)@(Ni) was obtained. 0.60 Fe 0.17 Mn 0.20 Zn 0.01 Zr 0.01 Ta 0.01 O2)2 cathode material.

[0078] ICP analysis of the dried precursor revealed Ni, Fe, Mn, Zn, Zr, and Ta content. The mass percentages of these elements were 29.05%, 8.41%, 9.23%, 0.52%, 0.79%, and 1.53%, respectively. Converted to relative molar ratios, the actual precursor was Ni. 0.5902 Fe 0.1795 Mn 0.2003 Zn 0.0095 Zr 0.0103 Ta 0.0102 The relative molar ratios of various elements in the CO3 precursor basically conform to the set Ni. 0.60 Fe 0.17 Mn 0.20 Zn 0.01 Zr 0.01 Ta 0.01CO3 precursor target. The morphology and particle size distribution of this precursor are as follows: Figure 4 As shown. From Figure 4 It can be seen that the sodium-ion battery carbonate precursor is spherical, and the precursor particle size follows a normal distribution. The prepared precursor, after being calcined with sodium, yielded a cathode material with an initial discharge capacity of 155.89 mAh / g at 1C, and a capacity retention rate of 94.26% after 100 cycles. Figure 3 As shown. Example

[0079] A method for preparing a carbonate precursor for a sodium-ion battery cathode material may include the following steps: Step 1: Weigh 14.545g of magnesium sulfate according to the molar ratio of metal ions (nickel, iron, manganese, magnesium, titanium, tungsten) of 1:100, dissolve it in dilute sulfuric acid and stir well to prepare the first solution.

[0080] Step 2: Weigh 28.121 g of titanium tetroxide according to the stoichiometric ratio, wherein the molar ratio of titanium tetroxide to metal ions (nickel, iron, manganese, magnesium, titanium, tungsten) is 1:100. Dissolve it in 0.01 mol / L dilute sulfuric acid to prepare a second solution.

[0081] Step 3: Weigh sodium carbonate and sodium tungstate. Weigh 35.636g of sodium tungstate according to a molar ratio of 1:100 for the metal ions (nickel, iron, manganese, magnesium, titanium, and tungsten). Dissolve sodium carbonate and sodium tantalate in deionized water to prepare a third solution with a sodium carbonate concentration of 2mol / L at a dissolution temperature of 45℃.

[0082] Step 4: Mix deionized water with the complexing agent to prepare a 0.5 mol / L complexing agent solution; Step 5: Dissolve nickel sulfate, ferric sulfate, and manganese sulfate in deionized water at a stoichiometric ratio of 77:10:10, add a certain amount of antioxidant, stir well, and prepare a 2 mol / L first reaction system solution. Step 6: Add 0.5 mol / L ammonia water and 50 g ascorbic acid to a 10 L reactor, and continuously introduce nitrogen gas into the reactor at 1.5 L / min to prepare a 3 L second reaction system bottom liquid. Step 7: Add the second solution, the third solution, and the ammonia solution to the second reaction base liquid in the reactor at a concurrent flow rate of 10 ml / min, and stir continuously at 500 r / min.

[0083] Step 8: The first solution, magnesium sulfate solution, is introduced into the first reaction system, Ni, Fe, Mn metal salt solution, at a rate of 10 ml / min. The mixture is stirred at 500 r / min until homogeneous. Simultaneously, the first solution and the Ni, Fe, Mn metal salt mixture are pumped into the reactor from step 7 at the same rate, ensuring that both reaction systems react simultaneously at the same rate. The pH of the first system is controlled at 3.5, and the pH of the second system is controlled at 7.8. The reaction is carried out continuously at 45°C for 36 hours. Then, feeding is stopped, and the mixture is aged for 12 hours to obtain the slurry.

[0084] Step 9: Collect the slurry, filter and wash it, dry the resulting filter cake in a 120℃ forced-air drying oven for 24 hours, and then sieve and demagnetize it to obtain the target precursor.

[0085] Step 10: The core-shell structured precursor was prepared and mixed with sodium carbonate in a molar ratio of (Ni+Fe+Mn+Mg+Ti+W):Na=2:1. The mixture was placed in a tube furnace under an oxygen atmosphere and calcined at 950℃ for 12h. After cooling to room temperature, the carbonate precursor cathode material was obtained.

[0086] ICP analysis of the dried precursor revealed Ni, Fe, Mn, Mg, Ti, and W content at mass percentages of 38.19%, 4.74%, 4.51%, 0.25%, 0.41%, and 1.49%, respectively. Converted to relative molar ratios, the actual precursor was Ni. 0.770 4Fe 0.1005 Mn 0.0972 Mg 0.0122 Ti 0.0101 W 0.0096 The relative molar ratios of various elements in the CO3 precursor basically conform to the set Ni. 0.77 Fe 0.10 Mn 0.10 Mg 0.01 Ti 0.01 W 0.01 CO3 precursor target. The morphology and particle size distribution of this precursor are as follows: Figure 5 As shown. From Figure 5 It can be seen that the carbonate precursor for sodium-ion batteries is spherical, and the precursor particle size follows a normal distribution. Example

[0087] A method for preparing a carbonate precursor for a sodium-ion battery cathode material may include the following steps: Step 1: Weigh 29.091 g of magnesium sulfate according to the molar ratio of metal ions (nickel, iron, manganese, yttrium, zirconium, molybdenum) of 1:100, dissolve it in 0.2 mol / L dilute sulfuric acid and stir well to prepare the first solution.

[0088] Step 2: Weigh yttrium sulfate according to the stoichiometric ratio, wherein 56.485 g of yttrium sulfate is weighed according to the molar ratio of metal ions (nickel, iron, manganese, yttrium, zirconium, molybdenum) of 0.5:100, and dissolve it in 0.01 mol / L dilute sulfuric acid to prepare a second solution.

[0089] Step 3: Weigh out sodium carbonate and sodium molybdate. Weigh out 49.939g of sodium molybdate according to a molar ratio of 1:100 for the metal ions (nickel, iron, manganese, yttrium, zirconium, molybdenum). Dissolve sodium carbonate and sodium molybdate in deionized water to prepare a third solution with a sodium carbonate concentration of 4mol / L at a dissolution temperature of 65℃.

[0090] Step 4: Mix deionized water and ammonia solution to prepare a 0.5 mol / L complexing agent solution; Step 5: Dissolve nickel sulfate, ferric sulfate, and manganese sulfate in deionized water at a stoichiometric ratio of 92.5:2:3, add a certain amount of ascorbic acid and stir well to prepare a 4 mol / L first reaction system solution. Step 6: Add 0.5 mol / L ammonia water and 50 g ascorbic acid to a 10 L reactor, and continuously introduce nitrogen gas into the reactor at 1.5 L / min to prepare a 3 L second reaction system bottom liquid. Step 7: Add the second solution, the third solution, and the ammonia solution to the second reaction base liquid in the reactor at a concurrent flow rate of 10 ml / min, and stir continuously at 500 r / min.

[0091] Step 8: The first solution, yttrium sulfate, is introduced into the first reaction system, Ni, Fe, Mn metal salt solution, at a rate of 10 ml / min and stirred at 500 r / min until homogeneous. Simultaneously, the first solution and the Ni, Fe, Mn metal salt mixture are pumped into the reactor in step 7 at the same rate, ensuring that both reaction systems react simultaneously at the same rate. The pH of the first system is controlled at 3.5, and the pH of the second system is controlled at 7.5. The reaction is carried out continuously at 65°C for 24 hours. Then, the feeding is stopped, and the mixture is aged for 12 hours to obtain the slurry.

[0092] Step 9: Collect the slurry, filter and wash it, dry the resulting filter cake in a 120℃ forced-air drying oven for 24 hours, and then sieve and demagnetize it to obtain the target precursor.

[0093] Step 10: The core-shell structured precursor was prepared and mixed with sodium carbonate in a molar ratio of (Ni+Fe+Mn+Y+Zr+Mo):Na=2:1. The mixture was placed in a tube furnace under an oxygen atmosphere and calcined at 950℃ for 12h. After cooling to room temperature, the carbonate precursor cathode material was obtained.

[0094] ICP analysis of the dried precursor revealed Ni, Fe, Mn, Y, Zr, and Mo content at mass percentages of 45.20%, 0.95%, 1.30%, 0.67%, 0.39%, and 0.85%, respectively. Converted to relative molar ratios, the actual precursor was Ni. 0.926 3Fe 0.0205 Mn 0.0284 Y 0.0091 Zr 0.0051 Mo 0.0106 The relative molar ratios of various elements in the CO3 precursor basically conform to the set Ni. 0.925 Fe 0.02 Mn 0.03 Y 0.01 Zr 0.005 Mo 0.01 CO3 precursor target. The morphology and particle size distribution of this precursor are as follows: Figure 6 As shown. From Figure 6 It can be seen that the carbonate precursor for sodium-ion batteries is spherical, and the precursor particle size follows a normal distribution.

[0095] Although the invention has been described above in conjunction with exemplary embodiments, those skilled in the art will understand that various modifications and changes can be made to the exemplary embodiments of the invention without departing from the spirit and scope defined by the claims.

Claims

1. A method for preparing a carbonate precursor for a sodium-ion battery cathode material, characterized in that, Includes the following steps: According to the precursor chemical formula Ni x Fe y Mn z G t J u M v CO3 ingredients: Weigh out salt G, dissolve it in an acidic solution to prepare a first solution, wherein G is at least one of Y, Mg, Zn and Al, J is at least one of Zr and Ti, M is at least one of W, Mo and Ta, 0.33≤x≤1, 0≤y≤0.33, 0≤z≤0.33, 0.0005≤t≤0.05, 0.0005≤u≤0.05, 0.0005≤v≤0.05, and x+y+z+t+u+v=1; Weigh out salt J, dissolve it in an acidic solution, and prepare a second solution; Weigh out salt M, dissolve it in a carbonate solution, and prepare a third solution; Deionized water and complexing agent are mixed to prepare a complexing agent solution; Prepare a mixed solution of Ni, Fe and Mn metal salts according to the general chemical formula of the precursors, and add an antioxidant to form the base liquid of the first reaction system; Complexing agent and antioxidant are added to the reaction vessel, and inert gas is introduced into the reaction vessel to form the bottom liquid of the second reaction system; The second solution, the third solution, and the complexing agent solution are added to the bottom liquid of the second reaction system, and the mixture is stirred continuously. While adding the first solution to the bottom liquid of the first reaction system, the bottom liquid of the first reaction system containing the first solution is introduced into the reaction vessel to carry out gradient doping of G metal elements; After the reaction, the slurry in the reactor was filtered, washed, dried, sieved, and demagnetized to obtain the carbonate precursor for sodium-ion battery cathode material. When the first solution is added to the bottom liquid of the first reaction system, the pH of the system is controlled at 8-10; when the bottom liquid of the first reaction system containing the first solution is introduced into the reaction vessel, the pH of the system is controlled at 10-12. The rate at which the first solution is added to the base liquid of the first reaction system is the same as the rate at which the base liquid of the first reaction system is added to the reaction vessel.

2. The method for preparing the carbonate precursor of the sodium-ion battery cathode material according to claim 1, characterized in that, The concentration of salt G in the first solution is 0.1 mol / L to 4 mol / L, the concentration of salt J in the second solution is 0.001 mol / L to 10 mol / L, the concentration of salt M in the third solution is 0.001 mol / L to 10 mol / L, the concentration of carbonate solution is 0.2 mol / L to 10 mol / L, and the concentration of complexing agent solution is 0.1 mol / L to 5 mol / L.

3. The method for preparing the carbonate precursor of the sodium-ion battery cathode material according to claim 1 or 2, characterized in that, The complexing agent used to prepare the complexing agent solution and the complexing agent added to the reaction vessel to form the bottom liquid of the second reaction system are at least one of ammonia, EDTA and 5-sulfosalicylic acid.

4. The method for preparing the carbonate precursor of the sodium-ion battery cathode material according to claim 1 or 2, characterized in that, The antioxidants forming the base liquid of the first reaction system and the base liquid of the second reaction system are at least one of ascorbic acid, citric acid and ethylenediaminetetraacetic acid.

5. The method for preparing the carbonate precursor of the sodium-ion battery cathode material according to claim 1 or 2, characterized in that, The temperature at which salt M dissolves in carbonate solution is 35℃~85℃, and salt M is at least one of sodium tantalate, potassium tantalate, sodium molybdate, potassium molybdate, sodium tungstate, and potassium tungstate; the temperature at which salt J dissolves in acidic solution is 35℃~85℃, and the pH during the dissolution process is 1~7, and salt J is at least one of zirconium nitrate, zirconium sulfate, zirconium acetate, and zirconium isopropoxide.

6. The method for preparing the carbonate precursor of the sodium-ion battery cathode material according to claim 1 or 2, characterized in that, The temperature at which the first solution is added to the bottom liquid of the first reaction system is 35℃~85℃, the reaction time is 1h~15h, and the precipitation time is 1-10h; the temperature at which the bottom liquid of the first reaction system with the first solution is introduced into the reaction vessel is 35℃~85℃, the reaction time is 1h~15h, and the precipitation time is 1h~10h.

7. The method for preparing the carbonate precursor of the sodium-ion battery cathode material according to claim 1 or 2, characterized in that, The acidic solution used to prepare the first solution and the second solution is at least one of dilute nitric acid, dilute hydrochloric acid, dilute sulfuric acid and acetic acid; the inert gas introduced into the reaction vessel is nitrogen, and the nitrogen introduction rate is 1L / min to 5L / min.

8. A carbonate precursor for a sodium-ion battery cathode material, characterized in that, It is prepared by the method for preparing carbonate precursor of sodium-ion battery cathode material according to any one of claims 1 to 7.

9. A sodium-ion battery cathode material, characterized in that, It is prepared from the sodium-ion battery cathode material carbonate precursor as described in claim 8.

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