Sodium ion battery positive electrode material carbonate precursor and preparation method thereof

Abstract

The invention provides a sodium ion battery positive electrode material carbonate precursor and a preparation method thereof. The preparation method comprises the following steps: 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 Ni, Fe and Mn metal salt mixed solution, and adding an antioxidant to form a base solution of a first reaction system; adding a complexing agent and an antioxidant into the reaction kettle to form a base solution of a second reaction system; adding the second solution, the third solution and the complexing agent solution into a base solution of a second reaction system; adding the first reaction system solution into a second reaction system while adding the first solution into the first reaction system, and carrying out coprecipitation reaction to form G metal element gradient doping; after the reaction is finished, obtaining a precursor; according to the method, in-situ element doping is carried out in the preparation process of the precursor, uniform doping of multiple elements can be achieved, the doping effect is good, and gradient doping of G metal salt is achieved.

Description

Technical Field

[0001] The present invention relates to the field of sodium ion batteries, and in particular to a carbonate precursor of a sodium ion battery cathode material and a preparation method thereof. Background Art

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

[0003] Layered oxide cathode materials exhibit the potential for high energy density and rapid charge and discharge in sodium-ion batteries, but their insufficient structural stability remains a key bottleneck hindering their industrial application. During sodium ion intercalation and deintercalation, the layered structure is susceptible to irreversible lattice distortion, leading to a continuous decay in cycling capacity. Specifically, the O3-type crystal structure readily transforms to the low-sodium P3 phase under high sodium deintercalation conditions, resulting in an irreversible reduction in active sites. Modulating crystal field stability through elemental doping is an effective strategy for improving material structural integrity, but conventional high-temperature solid-phase sintering methods have failed to achieve the desired modification results due to uneven spatial distribution of the doping elements and low lattice occupancy efficiency. Therefore, developing novel uniform doping processes to achieve atomically precise doping is a key path to improving the electrochemical performance of layered cathode materials. It is important to note that single-element doping systems can only achieve limited optimization of specific material properties. Multi-element synergistic doping strategies based on precursor design not only overcome the performance optimization bottleneck of single-element doping but also achieve comprehensive improvements in the overall material performance through synergistic modulation of interelement electronic effects. Summary of the Invention

[0004] The present invention proposes an innovative preparation design of carbonate precursors for sodium ion battery cathode materials, aiming to balance the high stability of layered oxide structure with the improvement of battery electrochemical performance. x Fe y Mn z G t J u M vThe CO3 multi-element composite system has the dual characteristics of atomic-level precise doping of multiple elements in specific proportions and gradient doping of G metal elements. The G metal element gradient doping includes gradually adding a first solution containing a G salt to a base liquid of a first reaction system containing Ni, Fe and Mn metal salts (forming a first reaction system), and at the same time gradually flowing the base liquid of the first reaction system containing the G element into a reactor containing a base liquid of the second reaction system, so that the G metal element gradient doping is performed in the reactor (forming a second reaction system). By constructing a synergistic mechanism of a dual reaction system, the parameters such as the pH value, temperature and time of the first reaction system and the second reaction system are precisely controlled to promote the directional deposition of metal ions in the solution to form a stable carbonate precursor that is uniformly dispersed at the atomic level. After cleaning and drying, the precursor and the sodium source material are evenly and fully mixed, and then synthesized by a solid-phase high-temperature calcination process in an oxygen atmosphere to finally obtain a nickel-iron-manganese-based layered oxide positive electrode material uniformly doped with multiple metal elements. This material achieves a dual breakthrough in improving the stability of layered oxide positive electrode materials and optimizing ion transport channels through the coordinated regulation of the electronic effects of multiple metal ions and gradient structure design.

[0005] On the one hand, the present invention provides a method for preparing a carbonate precursor of a positive electrode material for a sodium ion battery, comprising the following steps: x Fe y Mn z G t J u M v CO3 ingredients, weighing G salt, 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, x+y+z+t+u+v=1; weighing J salt, dissolving it in an acidic solution to prepare a second solution; weighing M salt, dissolving it in a carbonate solution to prepare a third solution; mixing deionized water with a complexing agent to prepare a complexing agent. The method comprises the following steps: preparing a mixed solution of Ni, Fe and Mn metal salts according to the precursor chemical formula, adding an antioxidant to form a bottom liquid of the first reaction system, adding a complexing agent and an antioxidant to a reactor, and introducing an inert gas into the reactor to form a bottom liquid of the second reaction system; adding the second solution, the third solution and the complexing agent solution to the bottom liquid of the second reaction system, and continuously stirring; adding the first solution to the bottom liquid of the first reaction system and introducing the bottom liquid of the first reaction system into the reactor to perform a gradient doping of the G metal element; filtering the slurry in the reactor after the reaction is completed, washing, drying, screening and demagnetizing to obtain a carbonate precursor of the positive electrode material of the sodium ion battery.

[0006] Furthermore, the concentration of G salt in the first solution is 0.1mol / L~4mol / L, the concentration of J salt in the second solution is 0.001mol / L~10mol / L, the concentration of M salt in the third solution is 0.001mol / L~10mol / L, the concentration of carbonate solution is 0.2mol / L~10mol / L, and the concentration of complexing agent solution is 0.1mol / ~5mol / L.

[0007] Furthermore, the complexing agent prepared into the complexing agent solution and the complexing agent added into the reaction kettle to form the second reaction system bottom liquid are at least one of ammonia water, EDTA and 5-flavour salicylic acid.

[0008] Furthermore, the antioxidant forming the first reaction system base liquid and the antioxidant forming the second reaction system base liquid is at least one of ascorbic acid, citric acid and ethylenediaminetetraacetic acid.

[0009] Furthermore, the temperature at which the M salt is dissolved in the carbonate solution is 35° C. to 85° C.; the M salt is at least one of sodium tantalate, potassium tantalate, sodium molybdate, potassium molybdate, sodium tungstate and potassium tungstate.

[0010] Furthermore, the temperature at which the J salt is dissolved in the acidic solution is 35° C. to 85° C., and the pH value during the dissolution process is 1 to 7; the J salt is at least one of zirconium nitrate, zirconium sulfate, zirconium acetate, and zirconium isopropoxide.

[0011] Furthermore, when the first solution is added to the first reaction system base liquid, the pH of the system can be controlled to be 8 to 10. When the first reaction system base liquid with the first solution added is passed into the reactor, the pH of the system can be controlled to be 10 to 12.

[0012] Furthermore, the temperature of the bottom liquid of the first reaction system when the first solution is added is 35°C~85°C, the reaction time is 1h~15h, and the sedimentation time is 1-10h; the temperature of the bottom liquid of the first reaction system added with the first solution is 35°C~85°C, the reaction time is 1h~15h, and the sedimentation time is 1h~10h.

[0013] Furthermore, the rate of addition of the first solution to the first reaction system base liquid is the same as the rate of addition of the first reaction system base liquid to the reactor; 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 reactor is nitrogen, and the nitrogen introduction rate is 1 L / min to 5 L / min.

[0014] Another aspect of the present invention provides a carbonate precursor for a positive electrode material of a sodium ion battery, which can be prepared by the above-mentioned method for preparing a carbonate precursor for a positive electrode material of a sodium ion battery.

[0015] Still another aspect of the present application provides a sodium-ion battery cathode material, which can be prepared from the sodium-ion battery cathode material carbonate precursor described above.

[0016] Compared with the prior art, the beneficial effects of the present application at least include at least one of the following:

[0017] (2) The precursor preparation of the present application adopts in-situ element doping to form a high-entropy type precursor, realizes uniform dispersion and uniform doping of multiple elements, improves the doping effect, and the doping effect is excellent.

[0018] (3) The method of the present application optimizes the sodium-ion deintercalation stress buffer and ion transport path through gradient doping, and forms a nanoscale composite interface, thereby improving the air stability and interface reaction kinetics.

[0019] (2) The present application has normal distribution of precursor particle size through the design of multi-element doping and partial element gradient doping, and the obtained layered cathode material has good electrochemical stability and does not need additional modification, and the process is short and easy to operate. BRIEF DESCRIPTION OF DRAWINGS

[0020] The above and other objects and features of the present application will become more apparent from the following description made with reference to the accompanying drawings, in which:

[0021] Figure 1 It is a schematic diagram of the precursor preparation device of the present application.

[0022] Figure 2 It is a precursor morphology and particle size distribution diagram prepared in Example 1.

[0023] Figure 3 It is a cathode material prepared in Example 2 under 1C cycle performance diagram.

[0024] Figure 4 It is a precursor morphology and particle size distribution diagram prepared in Example 2.

[0025] Figure 5 It is a precursor morphology and particle size distribution diagram prepared in Example 3.

[0026] Figure 6 It is a precursor morphology and particle size distribution diagram prepared in Example 4.

[0027] BRIEF DESCRIPTION OF DRAWINGS

[0028] 1-first dosing mechanism, 2-second dosing mechanism, 3-third dosing 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 DESCRIPTION

[0029] Hereinafter, a carbonate precursor of a positive electrode material for a sodium ion battery and a preparation method thereof according to the present invention will be described in detail with reference to the accompanying drawings and exemplary embodiments.

[0030] 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:

[0031] Step 1, according to the precursor chemical formula Ni x Fe y Mn z G t J u M v CO3 ingredients, weigh G salt, dissolve it in an acidic solution, and 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, x+y+z+t+u+v=1.

[0032] Step 2: Weigh salt J and dissolve it in an acidic solution to prepare a second solution.

[0033] Step 3, weighing M salt, dissolving it in carbonate solution, and preparing a third solution.

[0034] Step 4: Mix deionized water and the complexing agent to prepare a complexing agent solution.

[0035] Step 5: Prepare a mixed solution of Ni, Fe and Mn metal salts according to the precursor chemical formula, and add an antioxidant to form a base solution of the first reaction system.

[0036] Step 6: Add the complexing agent and antioxidant into the reactor, and introduce an inert gas into the reactor to form the bottom liquid of the second reaction system.

[0037] Step 7: Add the second solution, the third solution and the complexing agent solution into the base solution of the second reaction system and continue stirring.

[0038] Step 8: adding the first solution to the first reaction system base liquid and simultaneously passing the first reaction system base liquid added with the first solution into the reactor to perform gradient doping of the G metal element.

[0039] Step 9: After the reaction is completed, the slurry in the reactor is filtered, washed, dried, sieved, and demagnetized to obtain a carbonate precursor for the positive electrode material of a sodium ion battery.

[0040] In some embodiments, the acidic solution used to prepare the first solution in step 1 may be at least one of dilute nitric acid, dilute hydrochloric acid, dilute sulfuric acid, and acetic acid.

[0041] In some embodiments, the acidic solution used to prepare the second solution in step 2 may be at least one of dilute nitric acid, dilute hydrochloric acid, dilute sulfuric acid, and acetic acid.

[0042] In some embodiments, the carbonate in step 3 can be sodium carbonate.

[0043] In some embodiments, the complexing agent in step 4 can be one or more of ammonia, EDTA, and 5-xanthin salicylic acid. The concentration of the complexing agent solution can be 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.

[0044] In some embodiments, the antioxidant in step 5 can be any one of ascorbic acid, citric acid and ethylenediaminetetraacetic acid (EDTA).

[0045] In some embodiments, the complexing agent in step 6 can be one or more of ammonia, EDTA, and 5-xanthan gum. The antioxidant can be any one of ascorbic acid, citric acid, and ethylenediaminetetraacetic acid (EDTA).

[0046] In some embodiments, in step 8, a first reaction system is formed by passing the first solution into the bottom liquid of the first reaction system. At the same time, a peristaltic pump is used to pass the solution in the first reaction system into a reactor containing the second solution, the third solution, the complexing agent solution, and the bottom liquid of the second reaction system to form a second reaction system. By constructing a dual reaction system for synergistic effect and controlling the reaction pH, temperature, and time, a gradient doping of the G metal element is achieved, which promotes the directional deposition of metal ions in the solution to form a stable carbonate precursor that is uniformly dispersed at the atomic level. In the first reaction system, the G salt can be deposited on the surface of the Ni-Fe-Mn structure, and then the G salt is gradient doped over time and undergoes a co-precipitation reaction with the J salt and the M salt in the second system to ultimately form a carbonate precursor structure.

[0047] In some embodiments, the temperature of the first solution added to the first reaction system base liquid can be 35°C to 85°C, the reaction time can be 1h to 15h, and the sedimentation time can be 1h to 10h. For example, the temperature of the first solution added to the first reaction system base liquid can be 38°C to 75°C, the reaction time can be 3h to 12h, and the sedimentation time can be 3h to 8h. For another example, the temperature of the first solution added to the first reaction system base liquid can be 45°C to 62°C, the reaction time can be 5h to 8h, and the sedimentation time can be 4h to 7h.

[0048] In some embodiments, the temperature of the first reaction system bottom liquid added to the first solution is 35°C to 85°C, the reaction time is 1h to 15h, and the sedimentation time can be 1h to 10h. For example, the temperature of the first reaction system bottom liquid added to the first solution is 41°C to 80°C, the reaction time is 4h to 13h, and the sedimentation time can be 2h to 7h. For another example, the temperature of the first reaction system bottom liquid added to the first solution is 52°C to 63°C, the reaction time is 6h to 10h, and the sedimentation time can be 4h to 5h.

[0049] In some embodiments, the rate at which the first solution is added to the first reaction system base solution can be the same as the rate at which the first reaction system base solution containing the first solution is added to the reactor. The same rate ensures that the first reaction system and the second reaction system proceed simultaneously, and that the G metal is uniformly dispersed in a gradient pattern on the surface of the Ni-Fe-Mn metal oxide, thereby allowing the metal oxide mixed solution of the G salt and the salt solution in the second reaction system to react together to form a uniform carbonate precursor structure.

[0050] In some embodiments, when the first solution is added to the first reaction system base liquid, 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 first reaction system base liquid with the first solution added is passed into the reactor, the pH of the system is controlled to be 10-12, that is, the pH of the second reaction system is controlled to be 10-12. For example, the pH of the second reaction system is controlled to be 11.

[0051] In some embodiments, the J salt concentration may be 0.001 mol / L to 10 mol / L, the M salt concentration may be 0.001 mol / L to 10 mol / L, the first solution concentration may be 0.1 mol / L to 4 mol / L, and the carbonate solution concentration may be 0.2 mol / L to 10 mol / L. For example, the J salt concentration may be 0.15 mol / L to 8.3 mol / L, the M salt concentration may be 0.20 mol / L to 8.5 mol / L, the first solution concentration may be 0.5 mol / L to 3.2 mol / L, and the carbonate solution concentration may be 1.3 mol / L to 7.8 mol / L. For another example, the J salt concentration may be 1.32 mol / L to 5.6 mol / L, the M salt concentration may be 3.2 mol / L to 6.5 mol / L, the first solution concentration may be 2.1 mol / L to 2.8 mol / L, and the carbonate solution concentration may be 2.7 mol / L to 5.9 mol / L.

[0052] In some embodiments, the temperature at which the M salt is dissolved in the carbonate solution can be 35° C. to 85° C. For example, the temperature can be 38° C. to 81° C., 43° C. to 75° C., 51° C. to 69° C., or a combination thereof. The M salt can be at least one of sodium tantalate, potassium tantalate, sodium molybdate, potassium molybdate, sodium tungstate, and potassium tungstate.

[0053] In some embodiments, the J salt may be dissolved in an acidic solution at a temperature of 35°C to 85°C, and the pH during dissolution may be 1 to 7. For example, the J salt may be dissolved in an acidic solution at a temperature of 40°C to 75°C, and the pH during dissolution may be 2 to 6. For another example, the J salt may be dissolved in an acidic solution at a temperature of 48°C to 59°C, and the pH during dissolution may be 3 to 5. The J salt may be at least one of zirconium nitrate, zirconium sulfate, zirconium acetate, and zirconium isopropoxide.

[0054] In some embodiments, the acidic solution 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.

[0055] In some embodiments, the inert gas introduced into the reactor may be nitrogen, and the nitrogen introduction rate may be 1 L / min to 5 L / min. For example, the nitrogen introduction rate is 2 L / min to 4.5 L / min, 2.5 L / min to 3.5 L / min, or a combination thereof.

[0056] In some embodiments, the washing in step 9 can be done with deionized water. The drying temperature can be 120° C. to 170° C. The sieving mesh size can be 400±100 mesh.

[0057] In some embodiments, the base solution for forming the first reaction system can be obtained by adding an antioxidant to a mixed solution of Ni, Fe, and Mn metal salts and uniformly stirring the mixture at a stirring rate of 200 to 500 r / min. The stirring rate for continuous stirring in step 7 can be 200 to 500 r / min.

[0058] Another aspect of the present invention provides a carbonate precursor for a positive electrode material of a sodium ion battery, which can be prepared by the above-mentioned method for preparing a carbonate precursor for a positive electrode material of a sodium ion battery.

[0059] Another aspect of the present invention provides a sodium ion battery cathode material, which can be prepared from the carbonate precursor of the sodium ion battery cathode material described above. For example, the preparation method may include:

[0060] The carbonate precursor of the sodium-ion battery cathode material is uniformly and thoroughly mixed with a sodium source material, and then synthesized using a solid-phase high-temperature calcination process in an oxygen atmosphere to obtain a nickel-iron-manganese-based layered oxide cathode material uniformly doped with multiple metal elements. The high-temperature calcination temperature can be 600°C to 900°C, and the high-temperature calcination time can be 7°C to 12°C.

[0061] In order to better understand the present invention, the content of the present invention is further explained below with reference to specific examples, but the content of the present invention is not limited to the following examples.

[0062] The device used in the embodiment of the present invention is as follows Figure 1 As shown, it includes a first dosing mechanism 1, a second dosing mechanism 2, a third dosing 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.

[0063] The first dispensing mechanism 1 is used to prepare a first solution and is connected to the first reaction mechanism 12 via a first metering pump 4. The second dispensing mechanism 2 is used to prepare a second solution and is connected to the second reaction mechanism 13 via a second metering pump 5. The second reaction mechanism 13 can be a reactor. The third dispensing mechanism 3 is used to prepare a third solution and is connected to the second reaction mechanism 13 via a third metering pump 6. The liquid storage tank 9 is used to store a complexing agent solution and is connected to the second reaction mechanism 13 via a fifth metering pump 8. The first stirring system 10 is disposed within the first reaction mechanism 12 and is used to stir the reaction system within the first reaction mechanism. The second stirring system 11 is disposed within the second reaction mechanism 13 and is used to stir the reaction system within the second reaction mechanism. The first and second reaction mechanisms 12 and 13 are connected via a fourth metering pump 7. The first pH meter 14 is used to measure the pH value within the first reaction mechanism 12. The second pH meter 16 is used to measure the pH value within the second reaction mechanism 13. The first gas storage tank 15 is used to introduce inert gas into the first reaction mechanism 12. The second gas storage tank 17 is used to introduce inert gas into the second reaction mechanism 13. The reaction in the first reaction mechanism 12 forms a first reaction system, and the reaction in the second reaction mechanism 13 forms a second reaction system.

[0064] Specifically, the ingredients are prepared according to the general chemical formula of the precursor, G salt is weighed and dissolved in an acidic solution in the first dosing mechanism 1 to prepare a first solution, the flow rate is controlled by the first metering pump 4 and added to the Ni, Fe, and Mn metal salt mixed solution system in the first reaction mechanism 12. J salt is weighed, dissolved in an acidic solution, and prepared into a second solution in the second dosing mechanism 2. M salt is weighed, dissolved in a carbonate solution, and prepared into a third solution in the third dosing mechanism 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 solution and the third solution flow into the second reaction system bottom liquid in the second reaction mechanism 13 in parallel. The reactor of the second reaction mechanism 13 is provided with a stirring system and a pH meter. The co-precipitation reaction is carried out by controlling the pH. After the reaction is completed, the slurry is filtered, washed with water, and dried to obtain a sodium ion battery carbonate precursor.

[0065] In order to better understand the present invention, the content of the present invention is further explained below with reference to specific examples, but the content of the present invention is not limited to the following examples.

[0066] Example 1

[0067] A method for preparing a carbonate precursor for a sodium ion battery cathode material may include the following steps:

[0068] Step 1: Weigh 41.455 g of aluminum sulfate according to a 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 0.02 mol / L dilute sulfuric acid and stir evenly to prepare a first solution.

[0069] 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.

[0070] Step 3, weighing sodium carbonate and sodium molybdate, wherein 24.970 g of sodium molybdate is weighed according to a molar ratio of metal ions (nickel, iron, manganese, aluminum, titanium, molybdenum) of 1:100, and dissolving the sodium carbonate and sodium molybdate in deionized water to form a third solution containing sodium carbonate with a concentration of 0.5 mol / L, and the dissolution temperature is 30°C.

[0071] Step 4: Mix deionized water and the complexing agent to prepare a 0.5 mol / L complexing agent solution.

[0072] Step 5: dissolve nickel sulfate, iron sulfate, and manganese sulfate in deionized water at a stoichiometric ratio of 49:18:30, add 50 g of an antioxidant, and stir evenly to prepare a 0.5 mol / L first reaction system base solution.

[0073] Step 6: Add 0.5 mol / L ammonia water and 50 g ascorbic acid into a 10 L reactor, and continuously introduce nitrogen into the reactor at 1.5 L / min to prepare a 3 L second reaction system base liquid.

[0074] Step 7: Add the second solution, the third solution and the ammonia solution into the second reaction bottom liquid in the reactor at a flow rate of 10 ml / min, and continue stirring at 500 r / min.

[0075] Step 8: The first solution, aluminum sulfate solution, is passed into the first reaction system, Ni, Fe, and Mn metal salt solution at a rate of 10 ml / min, and stirred evenly at a rate of 500 r / min. At the same time, the first solution and the Ni, Fe, and Mn metal salt mixture are pumped into the reactor in step 7 at the same rate to ensure that the two reaction systems react at the same rate at the same time. The pH of the first system process is controlled to 3.5, and the pH of the second system process is controlled to 8.5. The reaction is continued at 35°C for 40 hours, and then the addition is stopped and aged for 8 hours to obtain a slurry.

[0076] Step 9: Collect the slurry, filter and wash it, dry the obtained filter cake in a forced air drying oven at 120° C. for 24 hours, and then sieve and demagnetize it to obtain the target carbonate structure precursor.

[0077] Step 10: The core-shell structure precursor was mixed with sodium carbonate in a molar ratio of (Ni+Fe+Mn+Al+Ti+Mo):Na=2:1, and the mixture was placed in a tube furnace under an oxygen atmosphere and calcined at 950°C for 12 hours. After cooling to room temperature, (Na2CO3)@(Ni 0.4836 Fe 0.1878 Mn 0.2965 Al 0.0105 Ti 0.0103 Mo 0.0105 O2)2 positive electrode material.

[0078] The Ni, Fe, Mn, Al, Ti and Mo contents of the dried precursor were analyzed by ICP. The element mass ratios were 24.17%, 8.92%, 13.85%, 0.24%, 0.42% and 0.86% respectively. After conversion to relative molar ratio, the actual precursor was Ni 0.4836 Fe 0.1878 Mn 0.2965 Al 0.0105 Ti 0.0103 Mo 0.0105 CO3, the relative molar ratio of various elements in the precursor basically meets the set Ni 0.49 Fe 0.18 Mn 0.30 Al 0.01 Ti 0.01 Mo 0.01 CO3 precursor target. The precursor morphology and particle size distribution are as follows Figure 2 As shown. Figure 2 It can be seen that the carbonate precursor of sodium ion battery is spherical and the particle size of the precursor conforms to the normal distribution.

[0079] Example 2

[0080] Step 1: weigh 9.758 g of zinc sulfate according to a molar ratio of metal ions (nickel, iron, manganese, zinc, zirconium, tantalum) of 1:100, dissolve it in dilute sulfuric acid and stir evenly to prepare a first solution.

[0081] Step 2: Weigh zirconium sulfate according to the stoichiometric ratio, wherein 17.152 g of zirconium sulfate is weighed according to the molar ratio of metal ions (nickel, iron, manganese, zinc, zirconium, tantalum) of 1:100, and dissolved in 0.01 mol / L dilute sulfuric acid to prepare a second solution.

[0082] Step 3, weighing sodium carbonate and sodium tantalate, wherein 15.273 g of sodium tantalate is weighed according to a molar ratio of 1:100 of metal ions (nickel, iron, manganese, zinc, zirconium, tantalum), and dissolving the sodium carbonate and sodium tantalate in deionized water to prepare a third solution containing sodium carbonate with a concentration of 1 mol / L, and the dissolution temperature is 45°C.

[0083] Step 4, mixing deionized water and a complexing agent to prepare a 0.5 mol / L complexing agent solution;

[0084] Step 5: dissolving nickel sulfate, iron sulfate, and manganese sulfate in deionized water at a stoichiometric ratio of 60:17:20, adding an antioxidant, and stirring evenly to prepare a 1 mol / L first reaction system solution;

[0085] 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;

[0086] Step 7: Add the second solution, the third solution and the ammonia solution into the second reaction bottom liquid in the reactor at a flow rate of 10 ml / min, and continue stirring at 500 r / min.

[0087] In step 8, the first solution, zinc sulfate solution, was introduced into the first reaction system, Ni, Fe, and Mn metal salt solution, at a rate of 10 ml / min, and stirred uniformly at a rate of 500 r / min. At the same time, the first solution and the mixed solution of Ni, Fe, and Mn metal salts were pumped into the reactor in step 7 at the same rate to ensure that the two reaction systems reacted simultaneously at the same rate. The pH of the first system process was controlled to 3.5, and the pH of the second system process was controlled to 8. The reaction was continued at 50° C. for 24 hours. Then, the addition was stopped and the mixture was aged for 12 hours to obtain a slurry.

[0088] Step 9: Collect the slurry, filter and wash it, dry the obtained filter cake in a forced air drying oven at 120° C. for 24 hours, and then sieve and demagnetize it to obtain the target precursor.

[0089] Step 10: The core-shell structure precursor prepared was mixed with sodium carbonate in a molar ratio of (Ni+Fe+Mn+Zn+Zr+Ta):Na=2:1, and the mixture was placed in a tube furnace under an oxygen atmosphere and calcined at 950°C for 12 hours. After cooling to room temperature, (Na2CO3)@(Ni 0.60 Fe 0.17 Mn 0.20 Zn 0.01 Zr 0.01 Ta 0.01 O2)2 positive electrode material.

[0090] The dried precursor was analyzed for Ni, Fe, Mn, Zn, Zr and Ta by ICP. The element mass distribution was 29.05%, 8.41%, 9.23%, 0.52%, 0.79% and 1.53%. After conversion to relative molar ratio, the actual precursor was Ni 0.5902 Fe 0.1795 Mn0.2003 Zn 0.0095 Zr 0.0103 Ta 0.0102 CO3, the relative molar ratio of various elements in the precursor basically meets the set Ni 0.60 Fe 0.17 Mn 0.20 Zn 0.01 Zr 0.01 Ta 0.01 CO3 precursor target. The precursor morphology and particle size distribution are as follows Figure 4 As shown. Figure 4 It can be seen that the carbonate precursor of sodium ion battery is spherical and the particle size of the precursor conforms to the normal distribution. The prepared precursor is calcined by mixing sodium, and the obtained positive electrode material has an initial discharge capacity of 155.89 mAh / g at 1C. After 100 cycles, the capacity retention rate is as high as 94.26%. Figure 3 shown.

[0091] Example 3

[0092] A method for preparing a carbonate precursor for a sodium ion battery cathode material may include the following steps:

[0093] Step 1: weigh 14.545 g of magnesium sulfate according to a molar ratio of metal ions (nickel, iron, manganese, magnesium, titanium, tungsten) of 1:100, dissolve it in dilute sulfuric acid and stir evenly to prepare a first solution.

[0094] Step 2: Weigh titanium dioxide according to the stoichiometric ratio, wherein 28.121 g of titanium dioxide is weighed according to the molar ratio of metal ions (nickel, iron, manganese, magnesium, titanium, tungsten) of 1:100, and dissolved in 0.01 mol / L dilute sulfuric acid to prepare a second solution.

[0095] Step 3, weighing sodium carbonate and sodium tungstate, wherein 35.636 g of sodium tungstate is weighed according to the molar ratio of metal ions (nickel, iron, manganese, magnesium, titanium, tungsten) of 1:100, and dissolving sodium carbonate and sodium tantalate in deionized water to prepare a third solution with a sodium carbonate concentration of 2 mol / L, and the dissolution temperature is 45°C.

[0096] Step 4, mixing deionized water and a complexing agent to prepare a 0.5 mol / L complexing agent solution;

[0097] Step 5: dissolving nickel sulfate, iron sulfate, and manganese sulfate in deionized water at a stoichiometric ratio of 77:10:10, adding a certain amount of antioxidant and stirring evenly to prepare a 2 mol / L first reaction system solution;

[0098] 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;

[0099] Step 7: Add the second solution, the third solution and the ammonia solution into the second reaction bottom liquid in the reactor at a flow rate of 10 ml / min, and continue stirring at 500 r / min.

[0100] Step 8: The first solution, magnesium sulfate solution, is passed into the first reaction system, Ni, Fe, and Mn metal salt solution at a rate of 10 ml / min, and stirred evenly at a rate of 500 r / min. At the same time, the first solution and the mixed solution of Ni, Fe, and Mn metal salts are pumped into the reactor in step 7 at the same rate to ensure that the two reaction systems react at the same rate at the same time. The pH of the first system process is controlled to 3.5, and the pH of the second system process is controlled to 7.8. The reaction is continued at 45° C. for 36 hours. Then, the addition is stopped and the mixture is aged for 12 hours to obtain a slurry.

[0101] Step 9: Collect the slurry, filter and wash it, dry the obtained filter cake in a forced air drying oven at 120° C. for 24 hours, and then sieve and demagnetize it to obtain the target precursor.

[0102] Step 10: Prepare a core-shell structure precursor and mix it evenly with sodium carbonate in a molar ratio of (Ni+Fe+Mn+Mg+Ti+W):Na=2:1. Place the mixture in a tube furnace under an oxygen atmosphere and calcine at 950°C for 12 hours. After cooling to room temperature, obtain a carbonate precursor positive electrode material.

[0103] The dried precursor was analyzed for Ni, Fe, Mn, Mg, Ti and W by ICP. The element weight distribution was 38.19%, 4.74%, 4.51%, 0.25%, 0.41% and 1.49% respectively. After conversion to relative molar ratio, the actual precursor was Ni 0.7704 Fe 0.1005 Mn 0.0972 Mg 0.0122 Ti 0.0101 W 0.0096 CO3, the relative molar ratio of various elements in the precursor basically meets the set Ni 0.77 Fe 0.10 Mn 0.10 Mg 0.01 Ti 0.01 W 0.01 CO3 precursor target. The precursor morphology and particle size distribution are as follows Figure 5 As shown. Figure 5 It can be seen that the carbonate precursor of sodium ion battery is spherical and the particle size of the precursor conforms to the normal distribution.

[0104] Example 4

[0105] A method for preparing a carbonate precursor for a sodium ion battery cathode material may include the following steps:

[0106] Step 1: weigh 29.091 g of magnesium sulfate according to a molar ratio of metal ions (nickel, iron, manganese, yttrium, zirconium, and molybdenum) of 1:100, dissolve it in 0.2 mol / L dilute sulfuric acid and stir evenly to prepare a first solution.

[0107] 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, and molybdenum) of 0.5:100 and dissolved in 0.01 mol / L dilute sulfuric acid to prepare a second solution.

[0108] Step 3, weighing sodium carbonate and sodium molybdate, wherein 49.939 g of sodium molybdate is weighed according to a molar ratio of metal ions (nickel, iron, manganese, yttrium, zirconium, molybdenum) of 1:100, and dissolving the sodium carbonate and sodium molybdate in deionized water to prepare a third solution containing sodium carbonate at a concentration of 4 mol / L, and the dissolution temperature is 65°C.

[0109] Step 4: Mix deionized water and ammonia solution to prepare a 0.5 mol / L complexing agent solution;

[0110] Step 5: dissolving nickel sulfate, iron sulfate, and manganese sulfate in deionized water at a stoichiometric ratio of 92.5:2:3, adding a certain amount of ascorbic acid, and stirring evenly to prepare a 4 mol / L first reaction system solution;

[0111] 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;

[0112] Step 7: Add the second solution, the third solution and the ammonia solution into the second reaction bottom liquid in the reactor at a flow rate of 10 ml / min, and continue stirring at 500 r / min.

[0113] Step 8: The first solution, yttrium sulfate solution, is introduced into the first reaction system, Ni, Fe, and Mn metal salt solution, at a rate of 10 ml / min, and stirred uniformly at a rate of 500 r / min. At the same time, the first solution and the mixed solution of Ni, Fe, and Mn metal salts are pumped into the reactor in step 7 at the same rate to ensure that the two reaction systems react at the same rate at the same time. The pH of the first system process is controlled to 3.5, and the pH of the second system process is controlled to 7.5. The reaction is continued at 65°C for 24 hours. Then, the addition is stopped and the mixture is aged for 12 hours to obtain a slurry.

[0114] Step 9: Collect the slurry, filter and wash it, dry the obtained filter cake in a forced air drying oven at 120° C. for 24 hours, and then sieve and demagnetize it to obtain the target precursor.

[0115] Step 10: Prepare a core-shell structure precursor and mix it evenly with sodium carbonate in a molar ratio of (Ni+Fe+Mn+Y+Zr+Mo):Na=2:1. Place the mixture in a tube furnace under an oxygen atmosphere and calcine at 950°C for 12 hours. After cooling to room temperature, obtain a carbonate precursor positive electrode material.

[0116] The dried precursor was analyzed for Ni, Fe, Mn, Y, Zr and Mo contents by ICP. The element weight ratios were 45.20%, 0.95%, 1.30%, 0.67%, 0.39% and 0.85% respectively. After conversion to relative molar ratio, the actual precursor was Ni 0.9263 Fe 0.0205 Mn 0.0284 Y 0.0091 Zr 0.0051 Mo 0.0106 CO3, the relative molar ratio of various elements in the precursor basically meets the set Ni 0.925 Fe 0.02 Mn 0.03 Y 0.01 Zr 0.005 Mo 0.01 CO3 precursor target. The precursor morphology and particle size distribution are as follows Figure 6 As shown. Figure 6 It can be seen that the carbonate precursor of sodium ion battery is spherical and the particle size of the precursor conforms to the normal distribution.

[0117] Although the present invention has been described above with reference to the exemplary embodiments, it will be apparent to those skilled in the art that various modifications and variations may be made to the exemplary embodiments of the present invention without departing from the spirit and scope defined in the claims.

Claims

1. A method for preparing a carbonate precursor for a sodium ion battery cathode material, characterized in that: The following steps are involved: According to the precursor chemical formula Ni x Fe y Mn z G t J u M v CO3 ingredients, weighing G salt, 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, x+y+z+t+u+v=1; Weigh salt J and dissolve it in an acidic solution to prepare a second solution; Weigh M salt and dissolve it in carbonate solution to prepare a third solution; mixing deionized water and a complexing agent to prepare a complexing agent solution; A mixed solution of Ni, Fe and Mn metal salts is prepared according to the precursor chemical formula, and an antioxidant is added to form a base solution of the first reaction system; Adding a complexing agent and an antioxidant into a reaction kettle, and introducing an inert gas into the reaction kettle to form a bottom liquid of the second reaction system; Add the second solution, the third solution and the complexing agent solution into the base solution of the second reaction system and continue stirring; The first solution is added to the first reaction system base liquid, and the first reaction system base liquid added with the first solution is introduced into the reaction kettle to perform gradient doping of the G metal element; After the reaction is completed, the slurry in the reactor is filtered, washed, dried, sieved, and demagnetized to obtain a carbonate precursor of the sodium ion battery positive electrode material.

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

3. The method for preparing a carbonate precursor for a sodium ion battery cathode material according to claim 1 or 2, wherein: The complexing agent prepared into the complexing agent solution and the complexing agent added into the reaction kettle to form the second reaction system bottom liquid are at least one of ammonia water, EDTA and 5-flavylsalicylic acid.

4. The method for preparing a carbonate precursor for a sodium ion battery cathode material according to claim 1 or 2, wherein: The antioxidant forming the first reaction system bottom liquid and the antioxidant forming the second reaction system bottom liquid is at least one of ascorbic acid, citric acid and ethylenediaminetetraacetic acid.

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

6. The method for preparing a carbonate precursor for a sodium ion battery cathode material according to claim 1 or 2, wherein: When the first solution is added to the first reaction system bottom liquid, the pH of the system is controlled to be 8-10; when the first reaction system bottom liquid added with the first solution is passed into the reactor, the pH of the system is controlled to be 10-12.

7. The method for preparing a carbonate precursor for a sodium ion battery cathode material according to claim 1 or 2, wherein: The temperature of the bottom liquid of the first reaction system when the first solution is added is 35℃~85℃, the reaction time is 1h~15h, and the sedimentation time is 1-10h; the temperature of the bottom liquid of the first reaction system when the first solution is added is 35℃~85℃, the reaction time is 1h~15h, and the sedimentation time is 1h~10h.

8. The method for preparing a carbonate precursor for a sodium ion battery cathode material according to claim 1 or 2, wherein: The rate of adding the first solution to the base liquid of the first reaction system is the same as the rate of adding the base liquid of the first reaction system to the reactor; 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 reactor is nitrogen, and the rate of introducing nitrogen is 1 L / min to 5 L / min.

9. A carbonate precursor for a sodium ion battery cathode material, characterized in that: The sodium ion battery positive electrode material is prepared by the method for preparing a carbonate precursor according to any one of claims 1 to 8.

10. A sodium ion battery cathode material, characterized in that: It is prepared from the carbonate precursor of the sodium ion battery positive electrode material according to claim 9.

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