Sodium-ion battery cathode material, its preparation method and use

Abstract

The present application provides a positive electrode material for sodium ion batteries, its preparation method and use. [Means] The preparation method includes the steps of: (1) mixing nickel source, manganese source and magnesium source to obtain a ternary salt solution; and (2) mixing the ternary salt solution, precipitant, complexing agent, boron source solution and organic additive in a reaction vessel in parallel flow to obtain a B-doped radially deposited hydroxide precursor; and (3) mixing the B-doped radially deposited hydroxide precursor obtained in step (1) with a sodium source and sintering to obtain the sodium ion battery positive electrode material. The present application optimizes the co-precipitation process to synergistically modify and adjust the chemical composition (B-doped) and microtopography (radial deposition of primary particles) of the positive electrode material, thereby simultaneously improving the element distribution uniformity, structural stability, cycle performance, rate performance and production efficiency of the sodium ion battery positive electrode material.

Description

[Technical Field]

[0001] The present application belongs to the technical field of sodium ion batteries, such as the positive electrode material of sodium ion batteries, its preparation method and use. [Background technology]

[0002] Rapid growth in demand for lithium-ion batteries in consumer electronics, power batteries, and energy storage has led to high lithium resource prices and increasingly tight supply. While sodium-ion batteries have a lower energy density than lithium-ion batteries, they offer advantages in terms of resource availability, cost, safety, rate performance, and low-temperature performance. Given this background, the development of sodium-ion batteries as a potential alternative to lithium-ion batteries holds significant economic and strategic value.

[0003] The core properties of high-performance sodium-ion batteries, such as energy density, cycle life, and rate performance, are primarily determined by the cathode material. x Mn y Mg z O2 has excellent overall performance and outstanding prospects for commercialization. Currently, industrial preparation of positive electrode materials mainly focuses on high-temperature solid-state and co-precipitation methods. The high-temperature solid-state method is simple and can achieve scalable preparation, but the chemical composition of the product is not sufficiently uniform, the particle morphology is irregular and prone to aggregation, and the tap density is low. Due to the above disadvantages, the consistency and yield of products from different batches are poor, and they cannot achieve optimal electrochemical performance.

[0004] CN110416521A discloses magnesium-doped ternary positive electrode materials for sodium-ion batteries and their preparation methods, and Mg-doped quaternary NaNi by sol-gel method 1 / 3-x Mg x Mn 1 / 3 Fe 1 / 3 O2 cathode material was constructed.

[0005] CN109817974A discloses a sodium-ion nickel-manganese-magnesium-iron quaternary positive electrode material and its preparation method, and uses electrospinning technology to prepare a Na-ion positive electrode with a P2 / O3 phase composite layer structure. x Ni y Mn z Mg 0.9-y-z Fe 0.1 O2 was prepared.

[0006] The preparation methods used in the above solutions are the sol-gel method or electrospinning method. Meanwhile, the products prepared by these methods are not sufficiently uniform, have low tap density, poor dispersion, poor consistency between different batches, low material yield, and poor reliability. On the other hand, these methods are not feasible for industrial-scale production and have little prospect for true commercialization. The use of a single modification method has limited performance improvement and does not achieve synergistic effects between different modification methods. Layered oxide cathode materials for sodium-ion batteries need to suppress multiple phase transitions and improve structural stability, cycle performance, rate performance, and energy density. A single modification method, such as element doping, can effectively improve structural stability, but fails to improve rate performance and energy density. Summary of the Invention [Problem to be solved by the invention]

[0007] The following is a summary of the subject matter described in detail in the present invention. This summary does not limit the scope of the claims.

[0008] The present application provides a positive electrode material for sodium ion batteries, its preparation method and use. By optimizing the co-precipitation process, the present application synergistically modifies and adjusts the chemical composition (B doping) and microtopography (radial deposition of primary particles) of the positive electrode material, thereby simultaneously improving the element distribution uniformity, structural stability, cycle performance, rate performance and production efficiency of the positive electrode material for sodium ion batteries. [Means for solving the problem]

[0009] The present application provides the following technical solutions. In aspect 1, the present embodiment comprises: 1. A method for preparing a positive electrode material for a sodium ion battery, comprising: (1) Mixing a nickel source, a manganese source, and a magnesium source to obtain a ternary salt solution, and then introducing the ternary salt solution, a precipitant, a complexing agent, a boron source solution, and an organic additive into a reaction vessel in parallel flow, and reacting them to obtain a B-doped radially deposited hydroxide precursor; and step (2) mixing the B-doped radially deposited hydroxide precursor obtained in step (1) with a sodium source, and sintering the mixture to obtain the positive electrode material for the sodium-ion battery. A method for preparing a positive electrode material for a sodium ion battery is provided.

[0010] The present application employs an industrially mature co-precipitation process to prepare a B-doped radially deposited sodium-ion battery cathode material. The prepared cathode material has uniform distribution at the atomic level, good spherical particle dispersion, high tap density, and good product consistency and reproducibility.

[0011] Compared with mixed deposition and planar deposition, radial deposition mitigates particle fracture due to lattice expansion caused by Li-ion intercalation, improving structural strength and cycle performance. Radial deposition also ensures the exposure of the active crystal plane (010), enhancing Li-ion intercalation kinetics and rate performance. Furthermore, the doping of the nonmetallic element B creates strong covalent B-O bonds, which give oxygen atoms more negative charges, effectively reducing excessive oxygen oxidation and improving the oxygen stability of the crystal lattice during deep sodium removal at high voltages. This suppresses multiple phase transitions and improves the voltage plateau and energy density.

[0012] In one embodiment, the nickel source described in step (1) comprises any one or a combination of at least two of nickel sulfate, nickel chloride, or nickel nitrate.

[0013] In one embodiment, the manganese source comprises any one or a combination of at least two of manganese sulfate, manganese chloride, or manganese nitrate.

[0014] In one embodiment, the magnesium source comprises any one or a combination of at least two of magnesium sulfate, magnesium chloride, or magnesium nitrate.

[0015] In one embodiment, the concentration of total metal ions in the ternary salt solution is 0.5-2.0 mol / L, such as 0.5 mol / L, 0.8 mol / L, 1 mol / L, 1.5 mol / L, or 2.0 mol / L.

[0016] In one embodiment, the precipitant used in step (1) comprises a sodium hydroxide solution having a concentration of 6 to 10 mol / L (e.g., 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, or 10 mol / L, etc.).

[0017] In one embodiment, the complexing agent comprises any one or a combination of at least two of aqueous ammonia, oxalic acid, sodium oxalate, or salicylic acid.

[0018] In one embodiment, the concentration of the complexing agent is 0.1-0.5 mol / L, such as 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, or 0.5 mol / L.

[0019] In one embodiment, the solute of the boron source solution includes any one or a combination of at least two of boric acid, boron oxide, and sodium borate.

[0020] In one embodiment, the concentration of the boron source solution is 1-3 mol / L, such as 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, or 3 mol / L.

[0021] In one embodiment, the organic additive comprises any one or a combination of at least two of ethanol, ethylene glycol, or hexadecyltrimethylammonium bromide.

[0022] In one embodiment, the flow rate of the ternary salt solution described in step (1) is 7-9 L / h, such as 7 L / h, 7.5 L / h, 8 L / h, 8.5 L / h, or 9 L / h.

[0023] In one embodiment, the flow rate of the precipitant is 2-4 L / h, such as 2 L / h, 2.5 L / h, 3 L / h, 3.5 L / h, or 4 L / h.

[0024] In one embodiment, the flow rate of the complexing agent is 1 to 1.5 L / h, such as 1 L / h, 1.1 L / h, 1.2 L / h, 1.3 L / h, 1.4 L / h, or 1.5 L / h.

[0025] In one embodiment, the flow rate of the boron source solution is 0.05 to 0.15 L / h, such as 0.05 L / h, 0.08 L / h, 0.1 L / h, 0.12 L / h, or 0.15 L / h.

[0026] In one embodiment, the flow rate of the organic additive is 0.1 to 0.3 L / h, such as 0.1 L / h, 0.15 L / h, 0.2 L / h, 0.25 L / h, or 0.3 L / h.

[0027] In one embodiment, the reaction temperature in step (1) is 30 to 60°C, such as 30°C, 35°C, 40°C, 50°C, or 60°C.

[0028] In one embodiment, the stirring speed of the reaction is 250-400 rpm, such as 250 rpm, 280 rpm, 300 rpm, 350 rpm, or 400 rpm.

[0029] In one embodiment, the pH of the reaction is between 9 and 12, such as 9, 9.5, 10, 11, or 12.

[0030] In one embodiment, the concentration of the complexing agent in the reaction system is 1.5 to 3.0 mmol / L.

[0031] In one embodiment, the reaction is followed by washing and drying. In one embodiment, the cleaning detergent comprises any one or a combination of at least two of hot water, liquid caustic soda, or ethanol.

[0032] In one embodiment, the doping amount of B in the hydroxide precursor of the B-doped radial deposition described in step (1) is 2000-10000 ppm, such as 2000 ppm, 4000 ppm, 6000 ppm, 8000 ppm, or 10000 ppm.

[0033] In one embodiment, the sodium source described in step (2) comprises sodium hydroxide and / or sodium carbonate.

[0034] In one embodiment, the molar ratio of the sodium source to the hydroxide precursor is 1 to 1.2.

[0035] In one embodiment, the sintering temperature is 800 to 1000°C, such as 800°C, 850°C, 900°C, 950°C, or 1000°C.

[0036] In one embodiment, the sintering time is 10 to 20 hours, such as 10 hours, 12 hours, 15 hours, 18 hours, or 20 hours.

[0037] In aspect 2, the present embodiment comprises: Produced by the method of embodiment 1, Provides positive electrode materials for sodium-ion batteries.

[0038] In aspect 3, the present embodiment comprises: The sodium-ion battery positive electrode material according to embodiment 2, A positive electrode tab is provided.

[0039] In aspect 4, the present embodiment comprises: comprising the positive electrode tab of embodiment 3; A sodium-ion battery is provided. [Effects of the Invention]

[0040] Compared to the prior art, the present invention has the following beneficial effects: (1) This application achieves a radially deposited microtopography by promoting the growth of specific crystal planes of the precursor, and further realizes the construction of a radially deposited microtopography of primary particles. This can mitigate particle fracture due to lattice expansion caused by Li-ion intercalation, improving structural strength and cycle performance. Meanwhile, radial deposition ensures the exposure of the active crystal plane (010), improving Li-ion intercalation kinetics and rate performance.

[0041] (2) The test data for the prepared sodium-ion battery cathode material coin-type half cell are as follows: 0.1C discharge capacity is 143mAh / g, 2C rate discharge capacity is 108mAh / g, and the capacity retention rate after 100 cycles is high at 92.78%.

[0042] (3) Compared with electrospinning, hydrothermal, and sol-gel methods, the B-doped radially deposited sodium-ion battery cathode material prepared by the industrially mature co-precipitation process can achieve uniform distribution at the atomic level, good dispersion of spherical particles, high tap density, good product consistency and reproducibility, and is easy to scale up and mass-produce.

[0043] (4) The battery manufactured using the cathode material of the present invention can achieve a discharge capacity of 138 mAh / g or more at 0.1 C and a discharge capacity of 105 mAh / g or more at 2 C. The capacity retention rate after 100 cycles can reach 87.53% or more, which means that the appropriate amount of B doping can improve the structural stability and cycle performance.

[0044] Other aspects may be understood upon reading and understanding the drawings and detailed description. The drawings are intended to provide a further understanding of the technical solution of the present application, constitute a part of the specification, and are used to interpret the technical solution of the present application together with the examples of the present application, and are not intended to limit the technical solution of the present application. [Brief explanation of the drawings]

[0045] [Figure 1] FIG. 2 is an XRD diagram of a positive electrode material of a sodium ion battery according to Example 1 of the present application. [Figure 2] FIG. 2 is an SEM image of a positive electrode material of a sodium ion battery according to Example 1 of the present application. [Figure 3] FIG. 2 is a SEM cross-sectional view of a positive electrode material of a sodium ion battery according to Example 1 of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0046] The technical solution of the present application will be further described below through specific embodiments, which are merely for the understanding of those skilled in the art and are not intended to specifically limit the present application. [Example]

[0047] This example provides a positive electrode material for a sodium ion battery, and the preparation method of the positive electrode material for a sodium ion battery is as follows:

[0048] (1) A 2 mol / L ternary sulfate solution with a metal molar ratio of Ni:Mn:Mg = 0.35:0.6:0.05, a 10 mol / L NaOH solution, a 0.2 mol / L sodium oxalate solution, a 1 mol / L sodium borate solution, and ethylene glycol were injected into a 200 L continuous stirring reactor at flow rates of 8 L / h, 3 L / h, 1.2 L / h, 0.1 L / h, and 0.2 L / h, respectively. The reaction temperature was maintained at 40°C, the pH at 10.2, and the stirring speed at 350 rpm. The reaction was carried out under these conditions for 48 hours. The reaction product was centrifuged, washed with 0.5 mol / L liquid caustic soda and hot water at 60°C, in that order, and dried in normal air at 120°C for 24 hours to obtain a B-doped radially deposited hydroxide precursor. The B doping amount was 5000 ppm.

[0049] (2) Na2CO3 and the precursor were uniformly mixed in a molar ratio of 1.05, and then sintered at 900°C for 15 hours to obtain the positive electrode material for the sodium-ion battery. [Example]

[0050] This example provides a positive electrode material for a sodium ion battery, and the preparation method of the positive electrode material for a sodium ion battery is as follows:

[0051] (1) A 1.8 mol / L ternary sulfate solution with a metal molar ratio of Ni:Mn:Mg = 0.35:0.6:0.05, an 8 mol / L NaOH solution, a 0.3 mol / L sodium oxalate solution, a 2 mol / L sodium borate solution, and ethanol were injected into a 200 L continuous stirring reactor at flow rates of 8.2 L / h, 3.2 L / h, 1.3 L / h, 0.12 L / h, and 0.25 L / h, respectively. The reaction temperature was maintained at 40 °C, the pH at 10, and the stirring speed at 350 rpm. The reaction was carried out under these conditions for 48 h. The reaction product was centrifuged, washed with 0.5 mol / L liquid caustic soda and hot water at 60 °C, in that order, and dried in normal air at 120 °C for 24 h to obtain a B-doped radially deposited hydroxide precursor. The B doping amount was 10,000 ppm.

[0052] (2) Na2CO3 and the precursor were mixed uniformly in a molar ratio of 1.1, and then sintered at 900°C for 15 hours to obtain the positive electrode material for the sodium-ion battery. [Example]

[0053] The only difference between this example and Example 1 is that the concentration of the complexing agent in the reaction system was controlled to 1.5 mmol / L; other conditions and parameters were exactly the same as those in Example 1. [Example]

[0054] The only difference between this example and Example 1 is that the concentration of the complexing agent in the reaction system was controlled to 3.0 mmol / L; other conditions and parameters were exactly the same as those in Example 1. [Example]

[0055] The only difference between this example and Example 1 is that the pH of the reaction system was 8.5; other conditions and parameters were exactly the same as those of Example 1. [Example]

[0056] The only difference between this example and Example 1 is that the pH of the reaction system was 12.5, and the other conditions and parameters were exactly the same as those of Example 1.

[0057] The only difference between this comparative example and Example 1 is that no organic additive was added, and the other conditions and parameters were exactly the same as those of Example 1.

[0058] The only difference between this comparative example and Example 1 is that no boron source was added; other conditions and parameters were exactly the same as those of Example 1.

[0059] Battery assembly and performance testing: Sodium ion cathode material, conductive carbon black, and adhesive PVDF, prepared in a mass ratio of 7.5:1.5:1, were weighed and uniformly dispersed in N-methylpyrrolidone (NMP) to prepare a conductive slurry. The material was then applied to aluminum foil, dried at 70°C, and cut out and weighed. The battery type was a coin battery, model number CR2032, with a glass fiber separator, sodium metal foil as the anode, 1M NaPF6 as the electrolyte, and an EC / DMC ratio of 1:1. A half-cell was assembled in a glove box filled with Ar gas, in the order of sodium metal foil, separator, cathode tab, spacer, and spring piece. The manufactured CR2032 coin-type half-cell had a voltage of 2.5 to 4.2 V (vs Li / Li). + Electrochemical tests were carried out in the voltage window between .

[0060] The test results are shown in Table 1.

[0061] [Table 1]

[0062] As can be seen from Table 1, according to Examples 1 and 2, the battery fabricated with the cathode material of the sodium ion battery of the present invention can reach a discharge capacity of 138mAh / g or more at 0.1C and a discharge capacity of 105mAh / g or more at 2C, and the capacity retention rate after 100 cycles can reach 87.53% or more, which shows that the appropriate amount of B doping can improve the structural stability and cycle performance.

[0063] Comparing Example 1 with Examples 3 to 6, in the process of preparing the cathode material for the sodium ion battery according to the present invention, if the pH of the reaction system is controlled to 9 to 12 and the concentration of the complexing agent in the reaction system is controlled to 1.5 to 3.0 mmol / L, a radially deposited sodium ion cathode material can be prepared. If the pH exceeds this range or the reaction conditions are not properly met, the prepared precursor will be in a random deposition or flat deposition mode, and it will be impossible to prepare a spherical precursor.

[0064] Comparison between Example 1 and Comparative Example 1 shows that in the preparation process of the sodium-ion battery cathode material of the present invention, an organic additive needs to be added to prepare a radially stacked sodium-ion battery cathode material. The organic additive adsorbs to specific crystal planes of the precursor, realizing oriented growth of the crystal planes, and thus obtaining a radially stacked sodium-ion battery cathode material.

[0065] Comparing Example 1 and Comparative Example 2, the present invention uses the doping of nonmetallic element B to establish strong covalent B-O bonds, which allows oxygen atoms to have more negative charges, effectively reducing excessive oxygen oxidation and improving the oxygen stability of the crystal lattice during deep sodium removal at high voltages, suppressing multiple phase transition reactions and improving the voltage plateau and cycle stability.

Claims

1. 1. A method for preparing a positive electrode material for a sodium ion battery, comprising: mixing a nickel source, a manganese source, and a magnesium source to obtain a ternary salt solution; and introducing the ternary salt solution, a precipitant, a complexing agent, a boron source solution, and an organic additive into a reaction vessel in parallel flow, and reacting them to obtain a hydroxide precursor of B-doped radial deposition, wherein the radial deposition is a radial deposition of primary particles; the precipitating agent comprises a sodium hydroxide solution having a concentration of 6 to 10 mol / L; the complexing agent includes any one or a combination of at least two of aqueous ammonia, oxalic acid, sodium oxalate, and salicylic acid; the organic additive comprises any one or a combination of at least two of ethanol, ethylene glycol, or hexadecyltrimethylammonium bromide; the pH of the reaction is between 9 and 12; Step (1), in which the concentration of the complexing agent in the reaction system is 1.5 to 3.0 mmol / L; and step (2) mixing the B-doped radially deposited hydroxide precursor obtained in step (1) with a sodium source, and sintering the mixture to obtain the positive electrode material for the sodium-ion battery. A method for preparing a positive electrode material for a sodium-ion battery.

2. The nickel source described in step (1) comprises any one or a combination of at least two of nickel sulfate, nickel chloride, or nickel nitrate. The preparation method according to claim 1.

3. The manganese source in step (1) comprises any one or a combination of at least two of manganese sulfate, manganese chloride, or manganese nitrate. The preparation method according to claim 1.

4. The magnesium source in step (1) comprises any one or a combination of at least two of magnesium sulfate, magnesium chloride, or magnesium nitrate. The preparation method according to claim 1.

5. The concentration of total metal ions in the ternary salt solution described in step (1) is 0.5-2.0 mol / L; The preparation method according to claim 1.

6. The concentration of the complexing agent described in step (1) is 0.1 to 0.5 mol / L; The preparation method according to claim 1.

7. The solute of the boron source solution described in step (1) includes any one or a combination of at least two of boric acid, boron oxide, and sodium borate; The preparation method according to claim 1.

8. The concentration of the boron source solution described in step (1) is 1 to 3 mol / L; The preparation method according to claim 1.

9. The flow rate of the ternary salt solution described in step (1) is 7-9 L / h; The preparation method according to claim 1.

10. The flow rate of the precipitant described in step (1) is 2-4 L / h; The preparation method according to claim 1.

11. The flow rate of the complexing agent described in step (1) is 1 to 1.5 L / h; The preparation method according to claim 1.

12. The flow rate of the boron source solution described in step (1) is 0.05 to 0.15 L / h; The preparation method according to claim 1.

13. The flow rate of the organic additive described in step (1) is 0.1 to 0.3 L / h; The preparation method according to claim 1.

14. The temperature of the reaction described in step (1) is 30 to 60°C. The preparation method according to claim 1.

15. The stirring speed of the reaction described in step (1) is 250 to 400 rpm; The preparation method according to claim 1.

16. The reaction described in step (1) is followed by washing and drying. The preparation method according to claim 1.

17. The cleaning detergent comprises any one or a combination of at least two of hot water, liquid caustic soda, or ethanol; 17. The method of claim 16.

18. The doping amount of B in the hydroxide precursor of the B-doped radial deposition described in step (1) is 2000-10000 ppm; The preparation method according to claim 1.

19. The sodium source described in step (2) comprises sodium hydroxide and / or sodium carbonate. The preparation method according to claim 1.

20. the molar blending ratio of the sodium source to the hydroxide precursor described in step (2) is 1 to 1.2, and the molar blending ratio of the sodium source to the hydroxide precursor is the molar blending ratio of sodium source / hydroxide precursor; 20. The method of claim 19.

21. The temperature of the sintering treatment described in step (2) is 800 to 1000 ° C.; The preparation method according to claim 1.

22. The sintering time described in step (2) is 10 to 20 hours; The preparation method according to claim 1.

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