Spherical battery positive electrode material precursor, positive electrode material and battery

Abstract

The chemical formula of the precursor is MnxFeyNizZn (1-x-y-z) (OH) 2, x is larger than 0.2 and smaller than 1, y is larger than 0 and smaller than 0.8, Z is larger than 0 and smaller than 0.8, and x + y + z is smaller than 1. According to the spherical dense sodium ion battery positive electrode material hydroxide precursor and the sodium ion battery positive electrode material provided by the invention, by limiting the content of each element, the positive electrode material prepared from the precursor has better structural stability, higher discharge medium voltage and higher discharge specific capacity.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery technology, specifically to a spherical, dense sodium-ion battery cathode material hydroxide precursor and its preparation method, a sodium-ion battery cathode material, and a sodium-ion battery. Background Technology

[0002] Sodium-ion batteries are considered the most promising for large-scale energy storage due to their advantages such as abundant resources, low price, and environmental friendliness. As an important component of sodium-ion batteries, the cathode material determines the cycle life, energy density, and rate performance of sodium-ion batteries. Nickel-iron-manganese-zinc based sodium-ion batteries have a high voltage platform, high discharge specific capacity, and long cycle life, and are considered the most promising cathode materials for sodium-ion batteries.

[0003] In materials synthesis, the precursor of sodium-ion batteries largely determines the performance of its cathode material. When synthesizing nickel-iron-manganese-zinc-based precursors using the co-precipitation method, the size, morphology, and structure of the precursor have a significant impact on subsequent sintering, thus affecting the final material's performance. Since Mn and Fe do not readily complex with ammonia, preparing hydroxide precursors with high Mn and Fe content is difficult to achieve uniform precipitation. Furthermore, the introduction of Zn leads to a decrease in the precursor's tap density, affecting the material's volumetric energy density. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a spherical, dense sodium-ion battery cathode material hydroxide precursor, cathode material, and battery, wherein the precursor has a tap density greater than 1.3 g / cm³. 3 Mn, Fe, Ni, and Zn can precipitate uniformly, forming a dense secondary spherical particle morphology.

[0005] This invention is achieved through the following technical solution:

[0006] A spherical battery cathode material hydroxide precursor with the chemical formula Mn x Fe y Ni z Zn (1-x-y-z) (OH)2, where 0.2<x<1, 0<y<0.8, 0<Z<0.8, x+y+z<1.

[0007] The precursor is spherical or near-spherical, with a D50 of 5–18 μm and a tap density greater than 1.3 g / cm³. 3 .

[0008] A cathode material, comprising the precursor as described above.

[0009] A battery comprising the positive electrode material as described above.

[0010] The method for preparing the precursor as described above is characterized by comprising the following steps:

[0011] (1) Prepare a mixed salt solution of manganese salt, iron salt and nickel salt according to the molar ratio of Mn, Fe and Ni in the molecular formula of the precursor;

[0012] (2) Preparation of the first alkaline solution containing zinc ions: This is prepared by mixing the zinc source with the alkaline solution, with a zinc ion molar concentration of 0.1–2.0 mol / L and OH⁻. - The molar concentration is 0.5–10 mol / L;

[0013] (3) Preparation of the second alkaline solution: OH - The molar concentration is 2–10 mol / L, used to adjust the pH of the reaction system;

[0014] (4) Prepare a composite complexing agent solution containing ammonia: Mix one of the following three substances with ammonia: tetrasodium iminodisuccinate, water-soluble chitosan, and disodium ethylenediaminetetraacetate;

[0015] (5) Preparation of the bottom liquid of the reactor: The antioxidant, the complexing agent solution and the alkaline solution are mixed together and the pH of the bottom liquid is adjusted to 10.9; the ammonia concentration is 5.5 g / L; the bottom liquid of the reactor occupies one-third of the total volume of the reactor;

[0016] (5) The reaction base liquid is passed into the reaction vessel and heated to 40-50°C. An oxygen-free atmosphere is maintained and the mixture is stirred. Then, a mixed salt solution, a first alkali solution, a second alkali solution and a composite complexing agent solution are passed in parallel to react. The feed rate of the mixed salt solution and the feed rate of the first alkali solution meet the stoichiometric ratio requirements of each element in the chemical formula in step (1). The feed rate of the second alkali solution meets the requirements of the set pH. After the reaction is completed, the resulting particles are aged. The reaction conditions remain unchanged during the aging process. After the aging is completed, the particles are separated, washed and dried to obtain the final product.

[0017] The manganese salt, iron salt, nickel salt, and zinc salt are one or more of sulfate, nitrate, or chloride salts, respectively, and the total molar concentration of manganese ions, iron ions, and nickel ions in the mixed solution of the manganese salt, iron salt, and nickel salt is 0.8–3.0 mol / L.

[0018] The first alkaline solution is OH-. - The molar concentration of zinc ions in the first alkaline solution is 0.5–10 mol / L, and the molar concentration of zinc ions in the second alkaline solution is 0.1–2.0 mol / L. The second alkaline solution is one or a mixture of several of the following aqueous solutions: NaOH, KOH, and LiOH.

[0019] The average molar concentration of tetrasodium iminodisuccinate in the complexing agent solution is controlled at 0.0001–0.3 mol / L, the average mass concentration of water-soluble chitosan is controlled at 0.01%–1%, and the average molar concentration of disodium ethylenediaminetetraacetate is controlled at 0.0001–0.25 mol / L. The ammonia concentration in the composite complexing agent solution in step (4) is controlled at 20–60 g / L.

[0020] During the reaction, the pH of the reaction vessel solution was maintained at 10.5-12, the ammonia concentration at 2-10 g / L, and the temperature at 40-50℃.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0022] This invention provides a spherical, dense sodium-ion battery cathode material hydroxide precursor and a sodium-ion battery cathode material. By limiting the content of each element, the cathode material prepared from this precursor exhibits better structural stability, higher discharge voltage, and higher discharge specific capacity. A spherical battery cathode material hydroxide precursor, whose main elements include Mn, Fe, Ni, and Zn, etc., allows for better electrochemical performance of the cathode material prepared from this composition by limiting the proportion of each element. During precursor preparation, since manganese and iron do not easily complex with ammonia, and zinc ions tend to nucleate independently during precipitation, this invention uses a specific ligand to achieve the slow release of manganese and ferrous ions, thereby achieving uniform precipitation. Furthermore, utilizing the amphoteric nature of zinc, zinc ions are added to the alkaline solution, and the ammonia concentration and pH of the system are controlled by limiting the amount of complexing agent and precipitant, completing crystal nucleation and growth under specific conditions. The prepared precursor is a spherical secondary particle formed by the agglomeration of plate-like primary particles, exhibiting higher tap density, and the manganese, iron, nickel, and zinc are uniformly distributed within the precursor.

[0023] This invention provides a method for preparing a spherical, dense sodium-ion battery cathode material hydroxide precursor. By using a specific complexing agent and changing the way Zn is added, Mn, Fe, Ni, and Zn are uniformly precipitated to obtain dense secondary spherical particles. The prepared cathode material exhibits higher volumetric energy density, structural stability, and electrochemical performance. Attached Figure Description

[0024] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and constitute a part of this invention, are not intended to limit the scope of the invention. In the drawings:

[0025] Figure 1 Mn prepared in Example 1 of this invention 0.4 Fe 0.3 Ni 0.2 Zn 0.1 SEM image of (OH)2.

[0026] Figure 2 The Mn prepared in Example 2 of this invention 0.4 Fe 0.3 Ni 0.2 Zn 0.1 SEM image of (OH)2.

[0027] Figure 3 The Mn prepared in Example 3 of this invention 0.4 Fe 0.3 Ni 0.2 Zn 0.1 SEM image of (OH)2.

[0028] Figure 4 Mn prepared as Comparative Example 1 of this invention 0.4 Fe 0.3 Ni 0.2 Zn 0.1 SEM image of (OH)2. Figure 5 Mn prepared in Example 1 of this invention 0.4 Fe 0.3 Ni 0.2 Zn 0.1 Electrochemical performance diagram of the cathode material corresponding to (OH)2. Detailed Implementation

[0029] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0030] Example 1

[0031] The chemical formula for preparing nickel-iron-manganese-zinc hydroxide is Mn 0.4 Fe 0.3 Ni 0.2 Zn 0.1 (OH)2, the preparation method is as follows;

[0032] Manganese sulfate, nickel sulfate, and ferrous sulfate were weighed as raw materials. The manganese, iron, and nickel content in the precursor was designed according to a Mn:Fe:Ni molar ratio of 4:3:2. These were then mixed with deionized water to prepare a mixed salt solution with a total metal ion concentration of 1.8 mol / L. Zinc sulfate was weighed as a raw material and mixed with sodium hydroxide to prepare the first alkaline solution, with a zinc ion concentration of 0.3 mol / L and a sodium hydroxide concentration of 5 mol / L. A 5 mol / L pure sodium hydroxide solution was then prepared as the second alkaline solution. A complexing agent of 5 g / L tetrasodium iminodisuccinate and 60 g / L ammonia solution was used.

[0033] Sodium sulfite, complexing agent solution, and second alkali solution are mixed to obtain the bottom liquid of the reactor. The pH of the bottom liquid is adjusted to 10.9; the ammonia concentration is 5.5 g / L; the bottom liquid of the reactor occupies one-third of the total volume of the reactor; the agitator is turned on and the speed is adjusted to 800 rpm, the temperature is raised to 40°C, and nitrogen gas is introduced to maintain the oxygen content of the bottom liquid in the reactor below 0.5%.

[0034] A mixed salt solution, a first alkali solution, a complexing agent solution, and a second alkali solution are introduced concurrently into the reactor; the pH of the solution in the reactor is controlled at 10.9, the ammonia concentration at 5.5 g / L, the temperature at 40℃, and the rotation speed at 800 rpm. Feeding is stopped when the D50 of the precipitated particles reaches 10 μm.

[0035] The obtained particles were aged in a reactor for 10 hours, and then filtered, washed, and dried to obtain manganese iron nickel hydrogen hydroxide. Figure 1 Mn prepared in Example 1 of this invention 0.4 Fe 0.3 Ni 0.2 Zn 0.1 SEM image of (OH)2.

[0036] Example 2

[0037] The chemical formula for preparing nickel-iron-manganese-zinc hydroxide is Mn 0.4 Fe 0.3 Ni 0.2 Zn 0.1 (OH)2, the preparation method is as follows;

[0038] Manganese sulfate, nickel sulfate, and ferrous sulfate were weighed as raw materials. The manganese, iron, and nickel content in the precursor was designed according to a Mn:Fe:Ni molar ratio of 4:3:2. These were then mixed with deionized water to prepare a mixed salt solution with a total metal ion concentration of 1.8 mol / L. Zinc sulfate was weighed as a raw material and mixed with sodium hydroxide to prepare the first alkaline solution, with a zinc ion concentration of 0.3 mol / L and a sodium hydroxide concentration of 5 mol / L. A 5 mol / L pure sodium hydroxide solution was then prepared as the second alkaline solution. 5 g / L water-soluble chitosan and 60 g / L ammonia solution were used as complexing agents.

[0039] Sodium sulfite, complexing agent solution, and second alkali solution are mixed to obtain the bottom liquid of the reactor. The pH of the bottom liquid is adjusted to 10.9; the ammonia concentration is 5.5 g / L; the bottom liquid of the reactor occupies one-third of the total volume of the reactor; the stirrer is turned on and the speed is adjusted to 800 rpm, the temperature is raised to 50°C, and nitrogen gas is introduced to maintain the oxygen content of the bottom liquid in the reactor below 0.5%.

[0040] A mixed salt solution, a first alkali solution, a complexing agent solution, and a second alkali solution are introduced concurrently into the reactor; the pH of the solution in the reactor is controlled at 10.9, the ammonia concentration at 5.5 g / L, the temperature at 50℃, and the rotation speed at 800 rpm. Feeding is stopped when the D50 of the precipitated particles reaches 10 μm.

[0041] The obtained particles were aged in a reactor for 10 hours, and then filtered, washed, and dried to obtain manganese iron nickel hydrogen hydroxide. Figure 2 The Mn prepared in Example 2 of this invention 0.4 Fe 0.3 Ni 0.2 Zn 0.1 SEM image of (OH)2.

[0042] Example 3

[0043] The chemical formula for preparing nickel-iron-manganese-zinc hydroxide is Mn 0.4 Fe 0.3 Ni 0.2 Zn 0.1 (OH)2, the preparation method is as follows;

[0044] Manganese sulfate, nickel sulfate, and ferrous sulfate were weighed as raw materials. The manganese, iron, and nickel content in the precursor was designed according to a Mn:Fe:Ni molar ratio of 4:3:2. These were then mixed with deionized water to prepare a mixed salt solution with a total metal ion concentration of 1.8 mol / L. Zinc sulfate was weighed as a raw material and mixed with sodium hydroxide to prepare the first alkaline solution, with a zinc ion concentration of 0.3 mol / L and a sodium hydroxide concentration of 5 mol / L. A 5 mol / L pure sodium hydroxide solution was then prepared as the second alkaline solution. A complexing agent of 5 g / L tetrasodium iminodisuccinate and 60 g / L ammonia solution was used.

[0045] Sodium sulfite, complexing agent solution, and second alkali solution are mixed to obtain the bottom liquid of the reactor. The pH of the bottom liquid is adjusted to 10.9; the ammonia concentration is 8 g / L; the bottom liquid of the reactor occupies one-third of the total volume of the reactor; the agitator is turned on and the speed is adjusted to 800 rpm, the temperature is raised to 50°C, and nitrogen gas is introduced to maintain the oxygen content of the bottom liquid in the reactor below 0.5%.

[0046] A mixed salt solution, a first alkali solution, a complexing agent solution, and a second alkali solution are introduced concurrently into the reactor; the pH of the solution in the reactor is controlled at 10.9, the ammonia concentration at 5.5 g / L, the temperature at 50℃, and the rotation speed at 800 rpm. Feeding is stopped when the D50 of the precipitated particles reaches 10 μm.

[0047] The obtained particles were aged in a reactor for 10 hours, and then filtered, washed, and dried to obtain manganese iron nickel hydrogen hydroxide.

[0048] Comparative Example 1

[0049] Nickel-iron-manganese-zinc hydroxide was prepared according to the method of Example 1, except that the complexing agent was only a 5.5 g / L ammonia solution.

[0050] Comparative Example 2

[0051] Nickel-iron-manganese-zinc hydroxide was prepared according to the method of Example 1, except that zinc was added to a salt solution. Figure 3 Mn prepared for Comparative Example 2 0.4 Fe 0.3 Ni 0.2 Zn 0.1 SEM image of (OH)2.

[0052] Electrochemical performance testing was conducted using the nickel-iron-manganese-zinc hydroxide prepared in Example 1 as a positive electrode material. The specific preparation method is as follows: the nickel-iron-manganese-zinc hydroxide precursor was mixed uniformly with one of sodium carbonate or sodium hydroxide in a mortar, preferably sodium carbonate, and calcined at 900°C for 10 hours to obtain the sodium-ion battery positive electrode material with the chemical formula Na. 0.85 Mn 0.4 Fe 0.3 Ni 0.2 Zn 0.1 O2. A coin cell was assembled using sodium metal as the negative electrode, polypropylene as the separator, and a NaClO4 solution in diethylene glycol dimethyl ether as the electrolyte. The assembled cell was subjected to electrochemical performance testing at 2-4V and 0.1C. The results are as follows. Figure 4 As shown, its discharge specific capacity is 135.99 mAh / g. The results demonstrate that the cathode material prepared using the nickel-iron-manganese-zinc hydroxide precursor exhibits excellent electrochemical performance.

[0053] from Figure 1 , Figure 2 , Figure 3 , Figure 4 As can be seen, the precursors obtained in Examples 1 and 2, compared to Comparative Examples 1 and 2, exhibit a more compact arrangement of primary particles and a higher volumetric energy density. Therefore, by specifying the type of complexing agent and the method of adding Zn ions, the arrangement of primary particles can be significantly improved, thereby enabling the precursor material to have a higher volumetric energy density.

[0054] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A spherical battery cathode material hydroxide precursor, characterized in that, Its chemical formula is Mn x Fe y Ni z Zn (1-x-y-z) (OH)2, where 0.2<x<1, 0<y<0.8, 0<Z<0.8, x+y+z<1.

2. The precursor according to claim 1, characterized in that, It is spherical or near-spherical, with a D50 of 5–18 μm and a tap density greater than 1.3 g / cm³. 3 .

3. A positive electrode material, characterized in that, Includes the precursor as described in claim 1 or 2.

4. A battery, characterized in that, Including the cathode material according to claim 3.

5. The method for preparing the precursor according to claim 1 or 2, characterized in that, Includes the following steps: (1) Prepare a mixed salt solution of manganese salt, iron salt and nickel salt according to the molar ratio of Mn, Fe and Ni in the molecular formula of the precursor; (2) Preparation of the first alkaline solution containing zinc ions: This is prepared by mixing the zinc source with the alkaline solution, with a zinc ion molar concentration of 0.1–2.0 mol / L and OH⁻. - The molar concentration is 0.5–10 mol / L; (3) Preparation of the second alkaline solution: OH - The molar concentration is 2–10 mol / L, used to adjust the pH of the reaction system; (4) Prepare a composite complexing agent solution containing ammonia: Mix one of the following three substances with ammonia: tetrasodium iminodisuccinate, water-soluble chitosan, and disodium ethylenediaminetetraacetate; (5) Preparation of reaction vessel bottom liquid: The antioxidant, complexing agent solution and alkaline solution are mixed to obtain the bottom liquid. The pH of the bottom liquid is adjusted to 10.9 and the ammonia concentration is 5.5 g / L. The bottom liquid accounts for one-third of the total volume of the reaction vessel. (6) The reaction base liquid is passed into the reaction vessel and heated to 40-50°C. An oxygen-free atmosphere is maintained and the mixture is stirred. Then, a mixed salt solution, a first alkali solution, a second alkali solution and a composite complexing agent solution are passed in parallel to react. The feed rate of the mixed salt solution and the feed rate of the first alkali solution meet the stoichiometric ratio requirements of each element in the chemical formula in step (1). The feed rate of the second alkali solution meets the requirements of the set pH. After the reaction is completed, the resulting particles are aged. The reaction conditions remain unchanged during the aging process. After the aging is completed, the particles are separated, washed and dried to obtain the final product.

6. The preparation method according to claim 5, characterized in that, The manganese salt, iron salt, nickel salt, and zinc salt are one or more of sulfate, nitrate, or chloride salts, respectively, and the total molar concentration of manganese ions, iron ions, and nickel ions in the mixed solution of the manganese salt, iron salt, and nickel salt is 0.8–3.0 mol / L.

7. The preparation method according to claim 5, characterized in that, The molar concentration of zinc ions is 0.1–2.0 mol / L.

8. The preparation method according to claim 5, characterized in that, If the complexing agent solution includes tetrasodium iminodisuccinate, the average molar concentration of tetrasodium iminodisuccinate is controlled at 0.0001–0.3 mol / L; if it includes water-soluble chitosan, the average mass concentration of water-soluble chitosan is controlled at 0.01%–1%; if it includes disodium ethylenediaminetetraacetate, the average molar concentration of disodium ethylenediaminetetraacetate is controlled at 0.0001–0.25 mol / L.

9. The preparation method according to claim 5, characterized in that, During the reaction, the pH of the reaction solution is maintained at 10.5-12, the ammonia concentration is 2-10 g / L, and the temperature is 40-50℃.

10. The preparation method according to claim 5, characterized in that, The ammonia concentration in the complexing agent solution in step (4) is controlled at 20-60 g / L.

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