Copper-containing sodium ion battery positive electrode material precursor and preparation method thereof, sodium ion battery positive electrode material and sodium ion battery
By coating a nickel-manganese-iron core with copper hydroxide, the problem of uneven doping of copper in the precursor of sodium-ion battery cathode material was solved, resulting in a precursor with high tap density and good morphology, which improved the energy density and cycle performance of the battery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JINCHI ENERGY MATERIALS CO LTD
- Filing Date
- 2026-01-16
- Publication Date
- 2026-05-12
AI Technical Summary
In the existing technology, copper is difficult to uniformly dope in the precursor of sodium-ion battery cathode material, resulting in uneven morphology, low tap density, and affecting battery performance.
A copper-doped sodium-ion battery cathode material precursor with a core-shell structure is used. The core is a nickel-manganese-iron hydroxide, and the shell is a copper hydroxide. Copper is coated on the nickel-iron-manganese core through a low-temperature, alkaline-free process, avoiding the use of ammonia as a complexing agent and controlling the reaction conditions to achieve uniform copper precipitation.
It improves the tap density of the precursor, enhances the energy density and structural stability of the battery, and improves the cycle performance of sodium-ion batteries.
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Figure CN122010199A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to sodium-ion batteries, and more particularly to a copper-containing precursor for sodium-ion battery cathode material and its preparation method, sodium-ion battery cathode material, and sodium-ion battery. Background Technology
[0002] Sodium-ion batteries, as a new generation of electrochemical energy storage devices, have shown broad application prospects in the field of large-scale energy storage due to their advantages such as abundant sodium resources, low cost, and environmental friendliness. The cathode material is a key component determining the performance of sodium-ion batteries. Among them, cathode materials based on transition metal oxides (such as layered oxides) have attracted much attention due to their high specific capacity and relatively mature preparation processes. In recent years, to improve the electrochemical performance and stability of materials, researchers have focused on developing quaternary precursor systems co-doped with multiple metals (such as nickel, iron, manganese, and copper), aiming to optimize the overall performance of the final cathode material through the synergistic effect between elements.
[0003] In the preparation of quaternary precursors, coprecipitation is widely used due to its ease of controlling composition and morphology. However, when copper is introduced, the preparation process faces significant challenges due to its unique physicochemical properties. Copper ions (Cu...) 2+ In alkaline precipitation environments, copper hydroxide (Cu(OH)2) is easily formed. However, copper hydroxide has high solubility in commonly used complexing agents (such as ammonia), which leads to its segregation during co-precipitation, making it difficult to uniformly incorporate into the precursor lattice. This compositional inhomogeneity can cause deterioration of the precursor particle morphology (such as surface roughness and non-dense structure), thereby affecting the tap density (TD) and electrochemical performance of the final cathode material.
[0004] Several solutions have been proposed in the prior art to address the aforementioned problems. For example, Chinese invention patent application CN117509752 A discloses a copper-containing precursor and its preparation method. This method involves preparing a copper salt solution and a salt solution containing nickel, iron, and manganese, respectively, and adding a chelating agent to the copper salt solution, followed by a two-step precipitation process to prepare the precursor. While this method alleviates the copper segregation problem to some extent, it still has significant shortcomings: firstly, the primary particle size of the obtained precursor is relatively fine, resulting in low interparticle packing efficiency and an unclear and potentially low tap density; secondly, the use of multiple complexing agents increases the complexity and cost of the process.
[0005] Another Chinese invention patent application, CN 118255400 A, describes a method for preparing nickel-iron-manganese-copper hydroxide precursors in stages, controlling particle size by first preparing seed crystals and then growing them. However, this technique uses trivalent iron salts as the iron source, which easily leads to insufficient crystallinity and loose structure in the precursor, resulting in a low tap density. At the same time, this method also relies on multiple complexing agents, which not only increases production costs but may also introduce the risk of residual impurities.
[0006] In summary, the current nickel-iron-manganese-copper precursor preparation technology still suffers from the following common defects: (1) Copper ions in the precursor exist in the form of copper hydroxide, which is difficult to stably dopant due to its easy solubility in ammonia water, and is prone to component segregation, resulting in poor morphological uniformity of the precursor; (2) The prepared precursor has a low tap density, which limits the volumetric energy density and processing performance of the final cathode material. Therefore, developing a precursor and its preparation method that can achieve uniform copper doping while possessing high tap density and good morphological control has become an urgent need to promote the development of sodium-ion battery technology. Summary of the Invention
[0007] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a copper-containing sodium-ion battery cathode material precursor and its preparation method, a sodium-ion battery cathode material, and a sodium-ion battery.
[0008] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows: A copper-containing precursor for sodium-ion battery cathode material, wherein the precursor is a copper-doped core-shell structure sodium-ion battery cathode material precursor, comprising a core and a shell covering the surface of the core. The core is nickel-manganese-iron hydroxide, and the shell is copper hydroxide. The precursor has the chemical formula Ni. x Cu y Fe z Mn 1-x-y-z (OH)₂, wherein 0.1≤x≤0.4, 0.04≤y≤0.1, 0.1≤z≤0.4, and the tap density TD of the precursor is not less than 1.40 g / cm³. 3 Further preferred values are 0.2≤x≤0.3 and 0.2≤z≤0.4. Even further preferred values are 0.3≤z≤0.4.
[0009] Doping with an appropriate amount of copper can improve the cycling performance of cathode materials under high voltage. If the molar amount of copper ions is too large, the copper ions will not be able to precipitate completely, affecting the morphology. If the amount is too small, it will affect the cycling performance of the cathode material under high voltage.
[0010] Preferably, the aforementioned sodium-ion battery cathode material precursor has an intercalation-type crystal structure, comprising thick, lamellar primary particles with ordered intercalation. Specifically, the secondary particles of the precursor are composed of lamellar primary particles with a thickness of 50-150 nm and a length of 1-2 μm.
[0011] Preferably, in the above-mentioned sodium-ion battery cathode material precursor, the secondary particles of the precursor are spherical or near-spherical, and the particle size D50 of the secondary particles is 3-5 μm.
[0012] As a general inventive concept, the present invention also provides a method for preparing a sodium-ion battery cathode material precursor as described above, comprising the following steps: (1) Dissolve the nickel source, iron source and manganese source in deionized water to prepare a nickel-iron-manganese salt mixed solution, and dissolve the copper source in deionized water to prepare a copper salt solution; more preferably, the copper source is the same type of compound as the nickel source, iron source and manganese source, and is a sulfate or nitrate or chloride.
[0013] (2) Add the bottom liquid of the reactor containing antioxidant B to the reactor, then introduce inert gas into the reactor to remove the air in the reactor, and continue to add a mixed solution of nickel-iron-manganese salt, liquid alkali solution and ammonia solution to the bottom liquid of the reactor under an inert atmosphere, control the pH to 9-12 to carry out co-precipitation reaction, solid-liquid separation, and obtain seed crystals; add antioxidant B to the bottom liquid of the reactor. Antioxidant B has strong reducing properties under alkaline conditions, which can prevent the slurry from being oxidized in the early stage of feeding; (3) The seed crystals are put back into the reactor, deionized water is added to prepare the bottom liquid of the reactor, the temperature of the bottom liquid is adjusted to 30-40℃, and then copper salt solution and alkaline solution are added to it in parallel without adding ammonia or other complexing agents to react and obtain slurry; (4) The slurry obtained in step (3) is aged, separated into solid and liquid, washed and dried to obtain a core-shell structured nickel-iron-manganese-copper-sodium ion battery cathode precursor.
[0014] In the above preparation method, preferably, in step (3), the reaction temperature is 30-40℃, the reaction time is 10-20h, the pH of the reaction process control system is 9.5-10.0, the stirring rate of the reaction vessel is 300-400r / min, the flow rate of the copper salt solution is 30-120mL / min, and the flow rate of the alkaline solution is 10-80mL / h.
[0015] In the above preparation method, preferably, in step (1), the total molar concentration of metal salts in the nickel-iron-manganese salt mixed solution is 1-4 mol / L; antioxidant A is also added to the nickel-iron-manganese salt mixed solution, and the concentration of antioxidant A is 0.1-0.2 g / L; antioxidant A includes at least one of ascorbic acid, sodium citrate, and citric acid.
[0016] In the above preparation method, preferably, in step (2), the D50 of the seed crystal is 3-3.5 μm.
[0017] In the above preparation method, preferably, in step (2), the temperature of the bottom liquid in the reaction vessel is 40-60℃, the pH value is 11.0-11.5, and the alkalinity C(NH4) is [not specified]. + The concentration ranges from 3.0 to 9.0 g / L. The coprecipitation reaction was carried out at a temperature of 40-60℃, a stirring rate of 400-600 r / min, a flow rate of 80-360 mL / min for the nickel-iron-manganese salt mixed solution, a flow rate of 10-60 mL / min for ammonia, and a flow rate of 30-150 mL / min for the alkaline solution. The pH was controlled at 11.0-11.5 for the first 30-40 hours of the reaction and at 10.5-11.0 for the last 20-30 hours of the reaction.
[0018] In the above preparation method, preferably, in step (2), the antioxidant B includes at least one of hydrazine hydrate, sodium citrate, hydrazine, and carbazide; the mass ratio of pure water to antioxidant B in the bottom liquid of the reaction vessel is 1:0.001-0.004.
[0019] In the above preparation method, preferably, the molar concentration of the copper salt solution is 0.5-2 mol / L; The concentration of the ammonia solution is 4-10 mol / L; The alkaline solution is a sodium hydroxide solution with a concentration of 8-12 mol / L.
[0020] In the above preparation method, preferably, in step (2), the flow rate of the inert gas is 10-30 L / h; when the inert gas is introduced into the reactor to remove the air in the reactor, the introduction time of the inert gas is 45-60 min; the inert gas or atmosphere includes nitrogen, argon or neon.
[0021] In the above preparation method, preferably, in step (2), the bottom liquid of the reaction vessel is 20%-90% of the volume of the reaction vessel.
[0022] As a general inventive concept, the present invention also provides a sodium-ion battery cathode material, which is prepared using the sodium-ion battery cathode material precursor as described above or using the sodium-ion battery cathode material precursor obtained by the preparation method described above.
[0023] As a general inventive concept, the present invention also provides a sodium-ion battery, including the sodium-ion battery positive electrode material as described above.
[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The tap density (TD) of the precursor of the nickel-iron-manganese-copper-sodium ion battery cathode material of the present invention is not less than 1.40 g / cm³. 3 High tap density effectively increases compaction density, thereby further enhancing battery energy density. This precursor has an intercalation-type crystal structure, comprising thick lamellar primary particles with ordered intercalation. The ordered intercalation of primary particles accelerates sodium ion transport rate and improves discharge capacity. Simultaneously, high tap density increases particle compactness, thereby reducing interparticle gaps, increasing the compaction density of the cathode material, and further increasing energy volume density. Furthermore, high tap density leads to a denser structure, enhancing structural stability, reducing particle breakage, and improving material cycle performance.
[0025] (2) This invention employs a low-temperature, alkaline-free process for the individual coating of Cu. Based on the preparation of an NFM (nickel-iron-manganese) core with high TD (dimerization precipitate), ammonia is not used as a complexing agent; instead, alkaline solution is directly used to precipitate Cu ions individually. Simultaneously, the reaction temperature is lowered, allowing the formed copper hydroxide precipitate to uniformly coat the NFM core without affecting its original morphology. The resulting primary particles are relatively coarse, with good sphericity and no fine particles on the surface. The TD can reach 1.4 g / cm³. 3 above. Attached Figure Description
[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0027] Figure 1 This is an electron microscope image of the sodium-ion battery cathode material precursor prepared in Example 1 of the present invention; Figure 2 This is an electron microscope image of the sodium-ion battery cathode material precursor prepared in Example 2 of the present invention; Figure 3 This is an electron microscope image of the sodium-ion battery cathode material precursor prepared in Comparative Example 1 of this invention. Detailed Implementation
[0028] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.
[0029] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.
[0030] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.
[0031] The particle size distribution in the following examples and comparative examples was tested using a Malvern 3000 particle size analyzer; the tap density was tested using a tap density meter, model BT-313, manufactured by Dandong Better Instruments Co., Ltd.
[0032] Example 1: A method for preparing a copper-containing sodium-ion battery cathode material precursor according to the present invention includes the following steps: (1) Prepare a metal salt mixed solution by mixing nickel sulfate, ferrous sulfate and manganese sulfate, wherein the molar ratio of nickel, iron and manganese in the metal salt mixed solution is 0.28:0.36:0.36 and the total concentration of metal ions is 2 mol / L; add ascorbic acid to the metal salt mixed solution at a concentration of 0.15 g / L; Prepare a copper sulfate solution with a copper ion concentration of 1 mol / L; Prepare ammonia solution with a concentration of 6.7 mol / L and sodium hydroxide solution with a concentration of 10.8 mol / L; spare.
[0033] (2) Pass 200L of pure water into a 300L reactor and heat it to 50℃. Add 1kg of 25% hydrazine hydrate, 120mL of sodium hydroxide solution and 2000mL of ammonia solution to the reactor to adjust the alkalinity of the bottom liquid of the reactor to 7g / L and the pH value to 11.10. Then pass N2 into the reactor at a flow rate of 20L / h for 1h to replace the air in the reactor.
[0034] (3) A mixed metal salt solution, ammonia, sodium hydroxide solution and nitrogen gas are continuously introduced into the bottom liquid of the reactor. The flow rate of the mixed metal salt solution is 360 mL / min, the flow rate of ammonia is 60 mL / min, the flow rate of sodium hydroxide solution is 150 mL / min, and the flow rate of nitrogen gas is 20 L / h. The pH value of the reaction system is controlled at 11.0-11.5 and the alkalinity is 7 g / L. The stirring rate in the reactor is 500 r / min. After the reaction is carried out for 30 h, the pH value of the reaction system is controlled at 10.5-11.0. After the reaction is continued for 20 h, the introduction of the mixed metal salt solution, ammonia and sodium hydroxide is stopped. The obtained slurry is subjected to solid-liquid separation to obtain the seed crystal of the precursor, with a D50 of about 3.3 μm.
[0035] (4) Put the seed crystals back into the reactor, add water to prepare the reaction base solution, set the temperature to 35°C, and introduce copper sulfate solution into the reaction system at a flow rate of 60 mL / min. Continue to introduce sodium hydroxide solution at a flow rate of 25 mL / min. Control the pH of the reaction system to 9.5-10.0 and the stirring speed in the reactor to 350 r / min. After reacting for 11 hours, stop introducing copper sulfate solution and sodium hydroxide solution.
[0036] (5) Add 150L of 10% sodium hydroxide solution to the reactor and age for 0.5h. Then filter the aged slurry. Wash the obtained solid particles repeatedly with pure water. Stop washing when the pH value of the deionized water after washing is less than 8.0. Then dry the solid particles at 80℃ for 4h and then heat to 120℃ for 14h to obtain Ni, the precursor of sodium-ion battery cathode material. 0.26 Cu 0.08 Fe 0.33 Mn 0.33 (OH)2, its electron micrograph is as follows Figure 1 As shown.
[0037] Example 2: A method for preparing a copper-containing sodium-ion battery cathode material precursor according to the present invention includes the following steps: (1) Prepare a metal salt mixed solution by mixing nickel sulfate, ferrous sulfate and manganese sulfate, wherein the molar ratio of nickel, iron and manganese in the metal salt mixed solution is 0.28:0.36:0.36 and the total concentration of metal ions is 2 mol / L; add ascorbic acid to the metal salt mixed solution at a concentration of 0.15 g / L; Prepare a copper sulfate solution with a copper ion concentration of 1 mol / L; Prepare ammonia solution with a concentration of 6.7 mol / L and sodium hydroxide solution with a concentration of 10.8 mol / L; spare.
[0038] (2) Pass 200L of pure water into a 300L reactor and heat it to 50℃. Add 1kg of 25% hydrazine hydrate, 120mL of sodium hydroxide solution and 2000mL of ammonia solution to the reactor to adjust the alkalinity of the bottom liquid of the reactor to 7g / L and the pH value to 11.10. Then pass N2 into the reactor at a flow rate of 20L / h for 1h to replace the air in the reactor.
[0039] (3) A mixed metal salt solution, ammonia, sodium hydroxide solution and nitrogen gas are continuously introduced into the bottom liquid of the reactor. The flow rate of the mixed metal salt solution is 360 mL / min, the flow rate of ammonia is 60 mL / min, the flow rate of sodium hydroxide solution is 150 mL / min, and the flow rate of nitrogen gas is 20 L / h. The pH value of the reaction system is controlled at 11.0-11.5 and the alkalinity is 7 g / L. The stirring rate in the reactor is 500 r / min. After the reaction is carried out for 30 h, the pH value of the reaction system is controlled at 10.5-11.0. After the reaction is continued for 20 h, the introduction of the mixed metal salt solution, ammonia and sodium hydroxide is stopped. The obtained slurry is subjected to solid-liquid separation to obtain the seed crystal of the precursor, with a D50 of about 3.2 μm.
[0040] (4) Put the seed crystals back into the reactor, add water to prepare the reaction base solution, set the temperature to 35°C, and introduce copper sulfate solution into the reaction system at a flow rate of 60 mL / min. Continue to introduce sodium hydroxide solution at a flow rate of 25 mL / min. Control the pH of the reaction system to 9.0-9.5 and the stirring rate in the reactor to 350 r / min. After reacting for 11 hours, stop introducing copper sulfate solution and sodium hydroxide solution.
[0041] (5) Add 150L of 10% sodium hydroxide solution to the reactor and age for 0.5h. Then filter the aged slurry. Wash the solid particles obtained by filtration repeatedly with pure water. Stop washing when the pH value of the deionized water after washing is less than 8.0. Then dry the solid particles at 80℃ for 4h and then heat to 120℃ for 14h to obtain the quaternary sodium-ion battery cathode material precursor Ni. 0.26 Cu 0.08 Fe 0.33 Mn 0.33 (OH)2, its electron micrograph is as follows Figure 2 As shown.
[0042] Example 3: A method for preparing a copper-containing sodium-ion battery cathode material precursor according to the present invention includes the following steps: (1) Prepare a metal salt mixed solution by mixing nickel sulfate, ferrous sulfate and manganese sulfate, wherein the molar ratio of nickel, iron and manganese in the metal salt mixed solution is 0.28:0.36:0.36 and the total concentration of metal ions is 2 mol / L; add ascorbic acid to the metal salt mixed solution at a concentration of 0.15 g / L; Prepare a copper sulfate solution with a copper ion concentration of 1 mol / L; Prepare ammonia solution with a concentration of 6.7 mol / L and sodium hydroxide solution with a concentration of 10.8 mol / L; spare.
[0043] (2) Pass 200L of pure water into a 300L reactor and heat it to 50℃. Add 1kg of 25% hydrazine hydrate, 120mL of sodium hydroxide solution and 2000mL of ammonia solution to the reactor to adjust the alkalinity of the bottom liquid of the reactor to 7g / L and the pH value to 11.10. Then pass N2 into the reactor at a flow rate of 20L / h for 1h to replace the air in the reactor.
[0044] (3) A mixed metal salt solution, ammonia, sodium hydroxide solution and nitrogen gas are continuously introduced into the bottom liquid of the reactor. The flow rate of the mixed metal salt solution is 360 mL / min, the flow rate of ammonia is 60 mL / min, the flow rate of sodium hydroxide solution is 150 mL / min, and the flow rate of nitrogen gas is 20 L / h. The pH value of the reaction system is controlled at 11.0-11.5 and the alkalinity is 7 g / L. The stirring rate in the reactor is 500 r / min. After the reaction is carried out for 30 h, the pH value of the reaction system is controlled at 10.5-11.0. After the reaction is continued for 20 h, the introduction of the mixed metal salt solution, ammonia and sodium hydroxide is stopped. The obtained slurry is subjected to solid-liquid separation to obtain the seed crystal of the precursor, with a D50 of about 3.4 μm.
[0045] (4) Put the seed crystals back into the reactor, add water to prepare the reaction base solution, set the temperature to 35°C, and introduce copper sulfate solution into the reaction system at a flow rate of 60 mL / min. Continue to introduce sodium hydroxide solution at a flow rate of 25 mL / min. Control the pH of the reaction system to 10.0-10.5 and the stirring speed in the reactor to 350 r / min. After reacting for 11 hours, stop introducing copper sulfate solution and sodium hydroxide solution.
[0046] (5) Add 150L of 10% sodium hydroxide solution to the reactor and age for 0.5h. Then filter the aged slurry. Wash the solid particles obtained by filtration repeatedly with pure water. Stop washing when the pH value of the deionized water after washing is less than 8.0. Then dry the solid particles at 80℃ for 4h and then heat to 120℃ for 14h to obtain the quaternary sodium-ion battery cathode material precursor Ni. 0.26Cu 0.08 Fe 0.33 Mn 0.33 (OH)2.
[0047] Example 4: A method for preparing a copper-containing sodium-ion battery cathode material precursor according to the present invention includes the following steps: (1) Prepare a metal salt mixed solution by mixing nickel sulfate, ferrous sulfate and manganese sulfate, wherein the molar ratio of nickel, iron and manganese in the metal salt mixed solution is 0.28:0.36:0.36 and the total concentration of metal ions is 2 mol / L; add ascorbic acid to the metal salt mixed solution at a concentration of 0.15 g / L; Prepare a copper sulfate solution with a copper ion concentration of 1 mol / L; Prepare ammonia solution with a concentration of 6.7 mol / L and sodium hydroxide solution with a concentration of 10.8 mol / L; spare.
[0048] (2) Pass 200L of pure water into a 300L reactor and heat it to 50℃. Add 1kg of 25% hydrazine hydrate, 120mL of sodium hydroxide solution and 2000mL of ammonia solution to the reactor to adjust the alkalinity of the bottom liquid of the reactor to 7g / L and the pH value to 11.10. Then pass N2 into the reactor at a flow rate of 20L / h for 1h to replace the air in the reactor.
[0049] (3) A mixed metal salt solution, ammonia, sodium hydroxide solution and nitrogen gas are continuously introduced into the bottom liquid of the reactor. The flow rate of the mixed metal salt solution is 360 mL / min, the flow rate of ammonia is 60 mL / min, the flow rate of sodium hydroxide solution is 150 mL / min, and the flow rate of nitrogen gas is 20 L / h. The pH value of the reaction system is controlled at 11.0-11.5 and the alkalinity is 7 g / L. The stirring rate in the reactor is 500 r / min. After the reaction is carried out for 30 h, the pH value of the reaction system is controlled at 10.5-11.0. After the reaction is continued for 20 h, the introduction of the mixed metal salt solution, ammonia and sodium hydroxide is stopped. The obtained slurry is subjected to solid-liquid separation to obtain the seed crystal of the precursor with a D50 of 3.3 μm.
[0050] (4) Put the seed crystals back into the reactor, add water to prepare the reaction base solution, set the temperature to 35°C, and introduce copper sulfate solution into the reaction system at a flow rate of 30 mL / min. Continue to introduce sodium hydroxide solution at a flow rate of 15 mL / min. Control the pH of the reaction system to 9.5-10.0 and the stirring speed in the reactor to 350 r / min. After reacting for 11 hours, stop introducing copper sulfate solution and sodium hydroxide solution.
[0051] (5) Add 150L of 10% sodium hydroxide solution to the reactor and age for 0.5h. Then filter the aged slurry. Wash the solid particles obtained by filtration repeatedly with pure water. Stop washing when the pH value of the deionized water after washing is less than 8.0. Then dry the solid particles at 80℃ for 4h and then heat to 120℃ for 14h to obtain the quaternary sodium-ion battery cathode material precursor Ni. 0.28 Cu 0.04 Fe 0.34 Mn 0.34 (OH)2.
[0052] Example 5: A method for preparing a copper-containing sodium-ion battery cathode material precursor according to the present invention includes the following steps: (1) Prepare a metal salt mixed solution by mixing nickel sulfate, ferrous sulfate and manganese sulfate, wherein the molar ratio of nickel, iron and manganese in the metal salt mixed solution is 0.333:0.333:0.333, and the total concentration of metal ions is 2 mol / L; add ascorbic acid to the metal salt mixed solution at a concentration of 0.15 g / L; Prepare a copper sulfate solution with a copper ion concentration of 1 mol / L; Prepare ammonia solution with a concentration of 6.7 mol / L and sodium hydroxide solution with a concentration of 10.8 mol / L; spare.
[0053] (2) Pass 200L of pure water into a 300L reactor and heat it to 50℃. Add 1kg of 25% hydrazine hydrate, 120mL of sodium hydroxide solution and 2000mL of ammonia solution to the reactor to adjust the alkalinity of the bottom liquid of the reactor to 7g / L and the pH value to 11.10. Then pass N2 into the reactor at a flow rate of 20L / h for 1h to replace the air in the reactor.
[0054] (3) A mixed metal salt solution, ammonia, sodium hydroxide solution and nitrogen gas are continuously introduced into the bottom liquid of the reactor. The flow rate of the mixed metal salt solution is 360 mL / min, the flow rate of ammonia is 60 mL / min, the flow rate of sodium hydroxide solution is 150 mL / min, and the flow rate of nitrogen gas is 20 L / h. The pH value of the reaction system is controlled at 11.0-11.5 and the alkalinity is 7 g / L. The stirring rate in the reactor is 500 r / min. After the reaction is carried out for 30 h, the pH value of the reaction system is controlled at 10.5-11.0. After the reaction is continued for 20 h, the introduction of the mixed metal salt solution, ammonia and sodium hydroxide is stopped. The obtained slurry is subjected to solid-liquid separation to obtain the seed crystal of the precursor with a D50 of 3.2 μm.
[0055] (4) Put the seed crystals back into the reactor, add water to prepare the reaction base solution, set the temperature to 35°C, and introduce copper sulfate solution into the reaction system at a flow rate of 80 mL / min. Continue to introduce sodium hydroxide solution at a flow rate of 35 mL / min. Control the pH of the reaction system to 9.5-10.0 and the stirring rate in the reactor to 350 r / min. After reacting for 11 hours, stop introducing copper sulfate solution and sodium hydroxide solution.
[0056] (5) Add 150L of 10% sodium hydroxide solution to the reactor and age for 0.5h. Then filter the aged slurry. Wash the solid particles obtained by filtration repeatedly with pure water. Stop washing when the pH value of the deionized water after washing is less than 8.0. Then dry the solid particles at 80℃ for 4h and then heat to 120℃ for 14h to obtain the quaternary sodium-ion battery cathode material precursor Ni. 0.30 Cu 0.10 Fe 0.30 Mn 0.30 (OH)2.
[0057] Comparative Example 1: The difference between this comparative example and Example 1 lies in the reaction conditions of step (3). The specific operation of step (3) in this comparative example is as follows: copper sulfate solution, ammonia water, and sodium hydroxide solution are introduced into the reaction system. The flow rate of the copper sulfate solution is 60 mL / min, the flow rate of the ammonia water is 10 mL / min, and the flow rate of the sodium hydroxide solution is 25 mL / min. The pH value of the reaction system is controlled at 10.0-10.5, the temperature at 50℃, and the stirring rate in the reactor is 350 r / min. After reacting for 11 hours, the introduction of copper sulfate solution, ammonia water, and sodium hydroxide solution is stopped. Everything else remains the same as in Example 1, and its electron micrograph is shown below. Figure 3 As shown.
[0058] contrast Figures 1-3 ,from Figure 1 and Figure 2 It can be seen that Example 1 has good sphericity, the primary particles exhibit a uniform intercalation shape, and the primary particles are thick. The secondary particles are composed of plate-like primary particles, with a thickness of approximately 50-150 nm and a length of 1-2 μm. From Figure 3 It can be seen that the precursor of Comparative Example 1 exhibits a loose structure, with primary particles in the form of thin flakes, and some individual precipitated particles. This is because the ammonia water forms a complex with copper ions, causing structural deformation and thinning of the primary particles. In comparison, the precursor morphology of the embodiment is superior, and the thicker primary particles are beneficial for improving the tap density.
[0059] Comparative Example 2: The difference between this comparative example and Example 1 is that the reaction temperature in step (4) is different. The reaction temperature in this comparative example is 20°C, while the rest is the same as in Example 1.
[0060] Comparative Example 3: The difference between this comparative example and Example 1 is that the reaction temperature in step (4) is different. The reaction temperature in this comparative example is 50°C, while the rest is the same as in Example 1.
[0061] Comparative Example 4: The difference between this comparative example and Example 1 is that in step (4), the pH of the reaction system is controlled to be 8.5-9.0, while the rest is the same as in Example 1.
[0062] Comparative Example 5: The difference between this comparative example and Example 1 is that in step (4), the pH of the reaction system is controlled to be 10.5-11.0, while the rest is the same as in Example 1.
[0063] The elemental content, D50, and tap density of the sodium-ion battery cathode material precursors in each embodiment and comparative example were tested, and the results are shown in Table 1.
[0064] Table 1. Elemental content, D50, and tap density of sodium-ion battery precursors prepared in Examples 1-5 and Comparative Examples 1-5
[0065] As can be seen from Table 1, the continuous introduction of ammonia water during the coating stage in Comparative Example 1 led to the formation of complexes, which affected the morphology of the primary particles and resulted in a decrease in tap density. Comparative Examples 2 and 3 changed the reaction temperature during the coating stage. At low temperatures, the precipitation reaction was incomplete, while at high temperatures, the precipitation of copper ions was affected by the activation energy, which affected the material structure and led to a decrease in tap density. In Comparative Examples 4 and 5, both excessively high and excessively low pH values affected the uniformity of copper ion precipitation, thereby affecting the tap density.
[0066] Preparation of sodium-ion battery cathode material: The precursors prepared in each example and comparative example were solid-state sintered with sodium carbonate at a Na / Me molar ratio of 0.8-1.2. The sintering temperature was 900℃ and the sintering time was 16h. The sintering atmosphere was air. Finally, sodium-ion battery cathode material was prepared.
[0067] Coin cell preparation: The prepared sodium-ion battery positive electrode material is mixed with conductive carbon black and PVDF binder at a mass ratio of 90:5:5. NMP solvent is added and thoroughly mixed to form a slurry. This slurry is then uniformly coated onto aluminum foil and dried at 120°C to form the positive electrode sheet. The positive electrode shell, positive electrode sheet, glass fiber separator, sodium metal sheet, gasket, spring, and negative electrode shell are assembled in that order. An appropriate amount of electrolyte is added, and the assembly is pressed and sealed to form a coin cell. The assembled coin cells were subjected to electrochemical testing on the Blue Electric testing system. Charge-discharge tests were conducted at 0.1C, 0.2C, and 1C, followed by cycle testing at 1C for 100 cycles. The test voltage range was 2-4V, and the test temperature was 25℃. The obtained electrochemical performance parameters are shown in Table 2.
[0068] Table 2. Electrochemical performance of precursors prepared in each example and comparative example.
[0069] As can be seen from Table 2, the electrochemical performance data of the coin cell are consistent with the trend of the precursor test data. The decrease in tap density will affect the energy density, thus leading to a decrease in capacity, while the loose structure will affect the stability, resulting in a deterioration in cycling performance.
Claims
1. A copper-containing precursor for a sodium-ion battery cathode material, characterized in that, The precursor has a core-shell structure, comprising a core and an outer shell covering the surface of the core. The core is a nickel-manganese-iron hydroxide, and the outer shell is a copper hydroxide. The chemical formula of the precursor is Ni. x Cu y Fe z Mn 1-x-y-z (OH)₂, wherein 0.1≤x≤0.4, 0.04≤y≤0.1, 0.1≤z≤0.4, and the tap density TD of the precursor is not less than 1.40 g / cm³. 3 .
2. The sodium-ion battery cathode material precursor as described in claim 1, characterized in that, The secondary particles of the precursor are composed of plate-like primary particles, the thickness of which is 50-150 nm and the length is 1-2 μm.
3. The sodium-ion battery cathode material precursor as described in claim 1, characterized in that, The secondary particles of the precursor are spherical or near-spherical, and the particle size D50 of the secondary particles is 3-5 μm.
4. A method for preparing a copper-containing sodium-ion battery cathode material precursor, characterized in that, Includes the following steps: (1) Dissolve the nickel source, iron source and manganese source in deionized water to prepare a mixed solution of nickel, iron and manganese salts, and dissolve the copper source in deionized water to prepare a copper salt solution; (2) Add the bottom liquid of the reactor containing antioxidant B to the reactor, then introduce inert gas into the reactor to remove the air in the reactor, and continue to add a mixed solution of nickel-iron-manganese salt, alkaline solution and ammonia solution to the bottom liquid of the reactor under an inert atmosphere, control the pH to 9-12 to carry out co-precipitation reaction, solid-liquid separation, and obtain seed crystals; (3) The seed crystals are put back into the reactor, deionized water is added to prepare the bottom liquid of the reactor, the temperature of the bottom liquid is adjusted to 30-40℃, and then copper salt solution and alkaline solution are added to it in parallel without adding ammonia or other complexing agents to react and obtain slurry; (4) The slurry obtained in step (3) is aged, separated into solid and liquid, washed and dried to obtain a precursor of nickel-iron-manganese-copper-sodium ion battery cathode material.
5. The preparation method according to claim 4, characterized in that, In step (3), the reaction temperature is 30-40℃, the reaction time is 10-20h, the pH of the reaction process is controlled at 9.5-10.0, the stirring rate of the reaction vessel is 300-400r / min, the flow rate of the copper salt solution is 30-120mL / min, and the flow rate of the alkaline solution is 10-80mL / h.
6. The preparation method according to claim 4, characterized in that, In step (1), the total molar concentration of metal salts in the nickel-iron-manganese salt mixed solution is 1-4 mol / L; antioxidant A is also added to the nickel-iron-manganese salt mixed solution, and the concentration of antioxidant A is 0.1-0.2 g / L; antioxidant A includes at least one of ascorbic acid, sodium citrate, and citric acid.
7. The preparation method according to claim 4, characterized in that, In step (2), the D50 of the seed crystal is 3-3.5 μm.
8. The preparation method according to claim 4, characterized in that, In step (2), the temperature of the bottom liquid in the reaction vessel is 40-60℃, the pH value is 11.0-11.5, and the alkalinity is 3.0-9.0 g / L. The alkalinity is expressed as NH4+. + Molar concentration meter; The coprecipitation reaction was carried out at a temperature of 40-60℃, a stirring rate of 400-600 r / min, a flow rate of 80-360 mL / min for the nickel-iron-manganese salt mixed solution, a flow rate of 10-60 mL / min for ammonia, and a flow rate of 30-150 mL / min for the alkaline solution. During the first 30-40 hours of the coprecipitation reaction, the pH was controlled at 11.0-11.5, and during the last 20-30 hours of the reaction, the pH was controlled at 10.5-11.
0.
9. The preparation method according to claim 4, characterized in that, In step (2), the antioxidant B includes at least one of hydrazine hydrate, sodium citrate, hydrazine, and carbazide; the mass ratio of pure water to antioxidant B in the bottom liquid of the reaction vessel is 1:0.001-0.
004.
10. The preparation method according to claim 4, characterized in that, The molar concentration of the copper salt solution is 0.5-2 mol / L; The concentration of the ammonia solution is 4-10 mol / L; The alkaline solution is a sodium hydroxide solution with a concentration of 8-12 mol / L.
11. A sodium-ion battery cathode material, characterized in that, It is prepared using the sodium-ion battery cathode material precursor as described in any one of claims 1 to 3 or using the sodium-ion battery cathode material precursor obtained by the preparation method as described in any one of claims 4 to 10.
12. A sodium-ion battery, comprising the sodium-ion battery cathode material as described in claim 11.