Zinc-doped sodium ion battery positive electrode precursor as well as preparation method and application thereof

Abstract

The invention provides a zinc-doped sodium ion battery positive electrode precursor as well as a preparation method and application thereof, and relates to the technical field of sodium ion batteries. Specifically, a first solution containing nickel salt, ferrite, manganese salt, zinc salt, an antioxidant and a first complexing agent is prepared; preparing a second solution containing a precipitant; preparing a third solution containing a second complexing agent; wherein the first complexing agent is used for complexing zinc ions and ferrous ions, and the second complexing agent is used for complexing nickel ions and manganese ions; and then through a co-precipitation reaction, controlling nucleation and growth of the precursor material according to the pH and ammonium concentration of a reaction system, and then carrying out post-treatment to obtain the zinc-doped sodium-ion battery positive electrode precursor. The precursor prepared by the method has the advantages of high tap density, high specific surface area, uniform components and the like, the particle sphericity and morphology uniformity are good, the preparation method is simple and easy to implement, the stability is good, and the method has a good batch prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion batteries, and in particular to a zinc-doped sodium ion battery positive electrode precursor and a preparation method and application thereof. Background Art

[0002] Sodium-ion batteries have good application prospects in large-scale energy storage fields such as energy storage grids due to their good safety performance, excellent cycle performance, and extremely wide distribution of sodium resources. Furthermore, among the positive electrode materials of sodium-ion batteries, layered transition metal oxides have become one of the most promising positive electrode materials for sodium-ion batteries due to their many advantages such as safety, high abundance, low cost, multiple transition metal ion selectivity, and simple preparation methods.

[0003] The key to the performance of layered transition metal oxide cathode materials lies in the preparation process of their precursors. Specifically, the precursors with high tap density are more compact after being converted into cathode materials, and can store more energy per unit volume, which helps to increase the capacity of the battery. Precursors with high specific surface area can provide more active sites, and sodium salts can fully react with the precursors during the sintering process. In addition, the appropriate introduction of other metal elements, such as zinc, into the nickel-iron-manganese system of sodium-ion batteries can reduce the Fe 3+ to Na + The irreversible migration of the layers reduces the lattice change and improves the structural stability, alleviating the Na + The voltage decays during the embedding and extraction process, thereby improving the cycle stability. However, the introduction of zinc makes it difficult to obtain a precursor with uniform element distribution, controllable morphology, high tap density, and high specific surface area when preparing sodium battery precursors by conventional co-precipitation methods. This is mainly because the precipitation equilibrium constants of Ni, Fe, Mn, and Zn metal ions are not in the same order of magnitude, and it is difficult to meet the requirements of co-precipitation from the perspective of chemical reaction.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The first purpose of the present invention is to provide a method for preparing a positive electrode precursor for a zinc-doped sodium ion battery. By optimizing the preparation method, the positive electrode precursor material has the advantages of uniform distribution of multi-metal elements, controllable morphology, high tap density and high specific surface area.

[0006] The second object of the present invention is to provide a zinc-doped sodium ion battery positive electrode precursor.

[0007] The third object of the present invention is to provide a positive electrode for a sodium ion battery.

[0008] A fourth object of the present invention is to provide a sodium ion battery.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0010] A method for preparing a zinc-doped sodium ion battery positive electrode precursor comprises the following steps:

[0011] (1) preparing a first solution comprising a nickel salt, a ferrous salt, a manganese salt, a zinc salt, an antioxidant and a first complexing agent; preparing a second solution comprising a precipitant; and preparing a third solution comprising a second complexing agent; wherein the first complexing agent is used for complexing zinc ions and ferrous ions, and the second complexing agent is used for complexing nickel ions and manganese ions;

[0012] (2) preparing a reaction base liquid; adding the first solution, the second solution and the third solution to the reaction base liquid at 50° C. to 55° C. in an inert gas atmosphere, controlling the pH of the reaction system to be 11 to 13 and the ammonium concentration to be 3 g / L to 6 g / L, and performing a nucleation stage of a coprecipitation reaction;

[0013] Then, the pH of the reaction system is controlled to be 10.5 to 11 and the ammonium concentration is controlled to be 2 g / L to 4 g / L under continuous feeding, and the growth stage of the coprecipitation reaction is carried out to obtain a precursor material with a particle size of 5 μm to 5.5 μm;

[0014] (3) Under continuous feeding, the pH of the reaction system is adjusted to 9.8-10.5, and a concentration treatment is performed to obtain a precursor material with a particle size of 9 μm-9.5 μm, and then the inert gas atmosphere is controlled until a precursor material with a particle size of 10±0.2 μm is obtained; then, washing, drying and demagnetization are performed in sequence to obtain a zinc-doped sodium ion battery positive electrode precursor.

[0015] A zinc-doped sodium ion battery positive electrode precursor is prepared by adopting the preparation method of the zinc-doped sodium ion battery positive electrode precursor.

[0016] A sodium ion battery positive electrode is prepared by using the zinc-doped sodium ion battery positive electrode precursor.

[0017] A sodium ion battery comprises the sodium ion battery positive electrode.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention provides a method for preparing a zinc-doped sodium ion battery positive electrode precursor and its expansive application in the field of sodium ion batteries. The precursor prepared by the present invention has the advantages of high tap density, high specific surface area, uniform composition, simple process, etc. Specifically, its specific surface area can reach 15 to 25 m 2 / g, the tap density can reach 1.7~2.2g / cm 3, the particle sphericity and morphology uniformity are good; at the same time, the metal elements (Zn, Fe, Mn, Ni) of the precursor prepared by the present invention are evenly distributed, which effectively solves the defect of element segregation in the conventional co-precipitation reaction process, and the preparation method is simple and easy, has good stability, can avoid batch differences caused by human factors, and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 Provides a SEM image of the positive electrode precursor material of Example 1 of the present invention;

[0022] Figure 2 Provides a SEM image of the positive electrode precursor material of Example 2 of the present invention;

[0023] Figure 3 Provides a SEM image of the positive electrode precursor material of Comparative Example 1 of the present invention;

[0024] Figure 4 A SEM image of the positive electrode precursor material of Comparative Example 2 of the present invention is provided. DETAILED DESCRIPTION

[0025] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but those skilled in the art will appreciate that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially. In addition, the terms "first", "second" and "third" are only used for descriptive purposes and cannot be interpreted as indicating or implying relative importance.

[0026] The first aspect of the present invention is to provide a method for preparing a positive electrode precursor of a zinc-doped sodium ion battery, which mainly includes the following steps: S1 preparation of a raw material solution, S2 two-stage co-precipitation reaction and sequentially realizing the nucleation and growth of the precursor material, and S3 shaping and post-treatment of the precursor material.

[0027] The conventional coprecipitation method is to mix a salt solution containing different metal ions with a precipitant and a complexing agent to perform a coprecipitation reaction and obtain a precursor of a positive electrode material for a sodium ion battery; while the ternary precursor preparation process using only ammonia water as a complexing agent is not suitable for preparing a zinc-doped sodium electric precursor, because ammonia water can only complex Ni and Mn ions, and cannot complex Fe and Zn ions. Therefore, in the present invention, in addition to removing the conventional Ni and Mn ion complexing agents, a class of Fe and Zn ion complexing agents are also introduced, so that the precipitation equilibrium constants of the four metal ions Ni, Fe, Mn, and Zn in the precipitation system reach the same order of magnitude, thereby achieving coprecipitation, thereby preparing a zinc-doped sodium electric precursor with high tapping, high specific surface, and uniform composition.

[0028] (1) preparing a first solution comprising a nickel salt, a ferrous salt, a manganese salt, a zinc salt, an antioxidant and a first complexing agent; preparing a second solution comprising a precipitant; preparing a third solution comprising a second complexing agent; wherein the first complexing agent is used for complexing zinc ions and ferrous ions, and the second complexing agent is used for complexing nickel ions and manganese ions.

[0029] As a preferred embodiment, the nickel salt, the ferrous salt, the manganese salt and the zinc salt are all soluble salts, including but not limited to sulfates, nitrates, chlorides and the like of the corresponding metals.

[0030] As a preferred embodiment, in the first solution, the sum of the concentrations of the nickel salt, the ferrous salt, the manganese salt and the zinc salt, that is, the concentration of the metal salt solution in the first solution is 1.0 mol / L to 3.0 mol / L; the concentration of the antioxidant is 0.2 g / L to 1.0 g / L, and the concentration of the first chelating agent is 10 g / L to 20 g / L.

[0031] As an optional embodiment, the concentration of the metal salt solution in the first solution includes but is not limited to any one of 1.0, 1.2, 1.5, 1.8, 2.0, 2.2, 2.5, 2.8, 3.0 (mol / L) or a numerical range consisting of any two of them, the concentration of the antioxidant includes but is not limited to any one of 0.2, 0.4, 0.5, 0.6, 0.8, 1.0 (g / L) or a numerical range consisting of any two of them, and the concentration of the first chelating agent includes but is not limited to any one of 10, 11, 12, 14, 15, 16, 18, 20 (g / L) or a numerical range consisting of any two of them.

[0032] Furthermore, regarding the dosage ratio of the nickel salt, the ferrous salt, the manganese salt and the zinc salt: the concentration ratio of the nickel salt, the ferrous salt and the manganese salt is carried out according to the preparation of conventional nickel-manganese-iron sodium-electrode oxide positive electrode materials, and the concentration dosage of the zinc salt is measured by the zinc doping amount. In some more preferred embodiments, the ratio of zinc ions in the zinc salt to the sum of the concentrations of the four metal ions is 0.05 to 0.15.

[0033] As a preferred embodiment, the antioxidant includes vitamin C; its main function is to prevent the ferrous ions in the first solution from being oxidized by dissolved oxygen in the solution during preparation or storage, but it is also necessary to avoid the introduction of other impurity ions due to the use of the antioxidant.

[0034] As a preferred embodiment, the first complexing agent includes one of sodium gluconate or EDTA-2Na, and sodium gluconate is more preferably used, which is mainly used as a complexing agent for Zn and Fe.

[0035] As a preferred embodiment, the precipitant includes one of sodium hydroxide or potassium hydroxide; further, in the second solution, the concentration of the precipitant is 6 mol / L to 14 mol / L, including but not limited to any one of 6, 7, 8, 10, 12, 13, 14 (mol / L) or a numerical range consisting of any two of them.

[0036] As a preferred embodiment, the second complexing agent includes ammonia water; further, in the third solution, the concentration of the ammonia water is 4 mol / L to 10 mol / L, including but not limited to any one of 4, 5, 6, 8, 9, 10 (mol / L) or a numerical range consisting of any two of them.

[0037] (2) preparing a reaction base liquid; adding the first solution, the second solution and the third solution to the reaction base liquid at 50° C. to 55° C. in an inert gas atmosphere, controlling the pH of the reaction system to 11 to 13 and the ammonium concentration to 3 g / L to 6 g / L, and performing a nucleation phase of a coprecipitation reaction; and then, controlling the pH of the reaction system to 10.5 to 11.0 and the ammonium concentration to 2 g / L to 4 g / L under a continuous feeding state, and performing a growth phase of a coprecipitation reaction to obtain a precursor material with a particle size of 5 μm to 5.5 μm.

[0038] It is worth noting that the "continuous feeding state" described in the present invention refers to the state of continuously adding the first solution, the second solution and the third solution. The continuous feeding state is maintained during the preparation of the precursor material in steps (2) to (3).

[0039] As a preferred embodiment, the filling gas of the inert gas atmosphere includes but is not limited to nitrogen, helium, neon, argon, etc.; the oxygen content in the inert gas atmosphere is less than 0.2% to prevent excessive oxidation of the reaction liquid from affecting the physical and chemical properties such as the morphology and specific surface area of ​​the precursor particles, and the inert gas atmosphere should be maintained before washing from step (2) to step (3).

[0040] As a preferred embodiment, the preparation of the reaction base solution includes the following steps: adding the second solution, the third solution and deionized water into a reaction container; the specific amount can be adjusted based on the properties of the reaction base solution, the pH of the reaction base solution is 11 to 13, and the ammonium concentration of the reaction base solution is 3 g / L to 6 g / L.

[0041] As a preferred embodiment, step (2) is carried out under stirring, and the stirring frequency can be optionally 50 rpm to 500 rpm.

[0042] As a preferred embodiment, the reaction time of the nucleation stage is 5 min to 120 min, including but not limited to any one of 5, 10, 20, 40, 50, 80, 100, 110, 120 (min) or a numerical range consisting of any two of them, more preferably 20 min to 60 min.

[0043] As a preferred embodiment, the total reaction time of the nucleation stage and the growth stage in step (2) is 40h to 100h, including but not limited to any one of 40, 45, 50, 60, 70, 80, 90, 95, 100 (h) or a numerical range consisting of any two of them, more preferably 40h to 80h.

[0044] It is understandable that a person skilled in the art may regard the growth of the particle size of the precursor material to 5 μm to 5.5 μm as a sign of the end of the reaction of this step and proceed to step (2).

[0045] As a preferred embodiment, in the nucleation stage and the growth stage, under the premise of satisfying the pH and ammonium root parameter limitations of the reaction system in each stage, the addition amounts of the three reaction solutions also satisfy: the ratio of the sum of the molar amounts of metal ions of nickel salt, ferrous salt, manganese salt and zinc salt in the first solution to the molar amount of the precipitant is 1:(1.9-2.1), and the molar ratio of the sum of the molar amounts of metal ions of nickel salt, ferrous salt, manganese salt and zinc salt in the first solution to the second complexing agent is 1:(0.2-0.4).

[0046] As a preferred embodiment, the ratio of the flow rate of the first solution in the nucleation stage to the flow rate in the growth stage is (1-2):(3-4), that is, there is a significant increase in the flow rate of the reaction raw materials in the growth stage to achieve an increase in the stability of the particle size of the precursor material.

[0047] As a more preferred embodiment, in the nucleation stage, the flow rate of the first solution is 40 g / min to 80 g / min; in the growth stage, the flow rate of the first solution is 120 g / min to 160 g / min.

[0048] As an optional embodiment, in the nucleation stage, the pH of the reaction system includes but is not limited to any one of 11, 11.2, 11.5, 11.8, 12, 12.2, 12.5, 12.8, 13 or a numerical range consisting of any two of them, and the ammonium concentration includes but is not limited to any one of 3, 3.5, 4, 4.5, 5, 5.5, 6 (g / L) or a numerical range consisting of any two of them.

[0049] As an optional embodiment, during the growth stage, the pH of the reaction system includes but is not limited to any one of 10.5, 10.6, 10.7, 10.8, 10.9, 11 or a numerical range consisting of any two of them, and the ammonium concentration includes but is not limited to any one of 2, 2.5, 3, 3.5, 4 (g / L) or a numerical range consisting of any two of them.

[0050] (3) adjusting the pH of the reaction system to 9.8-10.5, performing concentration treatment and obtaining a precursor material with a particle size of 9 μm-9.5 μm; controlling the inert gas atmosphere until a precursor material with a particle size of 10±0.2 μm is obtained; and then washing, drying and demagnetizing are performed in sequence to obtain a zinc-doped sodium ion battery positive electrode precursor.

[0051] As a preferred embodiment, the concentration treatment is performed by a concentrator, and the specific operation includes: turning on the concentrator feed pump, pumping the slurry of the reaction system to the concentrator, controlling the concentrator liquid level and clearing flow rate, and using the concentrator to further increase the slurry solid content. In some optional embodiments, after the concentration treatment, the solid content of the reaction system is 500g / L to 700g / L.

[0052] As a preferred embodiment, the controlling of the inert gas atmosphere comprises: reducing the amount of inert gas introduced to an oxygen content of 3% to 6%.

[0053] As an optional embodiment, the washing, the drying and the demagnetization can be carried out by conventional methods in the art, and the present invention does not make additional limitations thereto. Any operation method is feasible as long as the cleaning and demagnetization effects of the prerequisite materials can be achieved; further, the demagnetized material is sieved to obtain the zinc-doped sodium ion battery positive electrode precursor that fully meets 10±0.2μm.

[0054] The second aspect of the present invention is to provide a zinc-doped sodium ion battery positive electrode precursor, which is prepared by the preparation method of the zinc-doped sodium ion battery positive electrode precursor as described in the first aspect.

[0055] As a preferred embodiment, the molecular formula of the zinc-doped sodium ion battery positive electrode precursor is Ni n Zn x Fe y Mn z (OH)2, n+x+y+z=1, and 0.05≤x≤0.15; for the values ​​of x, y, and z, the distribution relationship of any existing zinc-iron-manganese oxide type positive electrode active material can be adopted, or, it can be understood that the present invention has been zinc-doped on the basis of any existing zinc-iron-manganese oxide type positive electrode active material; therefore, the present invention does not make any strict limitations on the values ​​of x, y, and z.

[0056] The third aspect of the present invention is to provide a sodium ion battery positive electrode, which is prepared using the zinc-doped sodium ion battery positive electrode precursor as described in the second aspect.

[0057] It is understandable that the sodium ion battery positive electrode can be prepared based on the zinc-doped sodium ion battery positive electrode precursor after heat treatment, and then combined with components such as a current collector and a bonding functional component; or, other positive electrode active materials are introduced into the sodium ion battery positive electrode, and the present invention does not impose any restrictions thereon. As long as the sodium ion battery positive electrode contains a material sourced from the zinc-doped sodium ion battery positive electrode precursor, the obtained electrode material with positive electrode function can be used as an embodiment of the present invention.

[0058] A fourth aspect of the present invention is to provide a sodium ion battery, comprising the sodium ion battery positive electrode as described in the third aspect.

[0059] It can be understood that, in addition to the sodium ion battery positive electrode, the sodium ion battery should include a negative electrode, an electrolyte, a diaphragm, and other necessary or non-essential functional elements or packaging components, etc., and those skilled in the art can arbitrarily select and combine them; when the sodium ion battery positive electrode described in the present invention is included in the sodium ion battery, whether or not other composite positive electrodes are used in the sodium ion battery, it can be regarded as an embodiment of the present invention.

[0060] Example 1

[0061] (1) Reaction raw material preparation process:

[0062] According to the chemical formula Ni 0.20 Zn 0.10 Fe 0.30 Mn 0.40 (OH)2 is used to prepare metal elements, and the molar percentages of nickel, iron, zinc and manganese elements are controlled as 20:10:30:40. Soluble sulfates of nickel, iron, zinc and manganese are selected and mixed with pure water to prepare a four-metal sulfate solution with a total concentration of 2.0 mol / L, to which 0.6 g / L of vitamin C and 15 g / L of sodium gluconate are added as a "mixed metal salt solution"; a sodium hydroxide aqueous solution with a concentration of 10.8 mol / L is prepared; and a 7.5 mol / L ammonia aqueous solution is prepared.

[0063] (2) The coprecipitation reaction process is as follows:

[0064] (2.1) Reaction nucleation stage:

[0065] Deionized water, ammonia solution and sodium hydroxide solution were added to the reactor, and the pH of the system was controlled to be 11.2, and the ammonium concentration was 4.5 g / L, which was used as the bottom liquid of the reactor. Nitrogen was introduced for 2 h before the reactor was opened, and the temperature of the reactor was adjusted to 55°C. The mixed metal salt solution, sodium hydroxide solution and ammonia solution prepared in step (1) were added to the reactor in parallel to carry out a coprecipitation reaction, wherein the flow rate of the mixed metal salt solution was controlled to be 60 g / min, and the molar ratio of the sodium hydroxide solution to the metal ions was OH / Me, which was 2.0, and the molar ratio of the ammonia solution to the metal ions was NH / Me, which was 0.3, based on the total amount of metal ions in the mixed metal salt solution; the pH of the reaction system in the reactor was continuously controlled to be 12, and the ammonium concentration was 4.5 g / L, and the reaction was continued for 40 minutes.

[0066] (2.2) Reaction growth stage:

[0067] The flow rates of the mixed metal salt solution, ammonia solution and sodium hydroxide solution were increased, wherein the flow rate of the mixed metal salt solution was increased to 140 g / min, while maintaining OH / Me at 2.0 and NH / Me at 0.3; the pH value of the reaction system in the reactor was continuously controlled to be 10.7, and the ammonium concentration was 3.0 g / L; the reaction was continued until the particle size of the precursor material in the slurry reached 5.2 μm.

[0068] (2.3) The second reaction growth stage:

[0069] Under the premise of maintaining the flow rate of the mixed metal salt solution, ammonia solution and sodium hydroxide solution, the pH of the reaction system in the reactor is controlled to be 10.2, the feed pump of the concentrator is turned on, the slurry is pumped to the concentrator, the liquid level and the clearing flow of the concentrator are controlled, and the solid content of the slurry is further increased by the concentrator; when the particle size of the precursor material in the slurry reaches 9.2 μm, the nitrogen intake is reduced to properly oxidize the slurry to increase the specific surface area, and when the particle size of the precursor material in the reactor reaches 10±0.2 μm, the feeding is stopped. The total reaction time of this step (2) is 60 hours.

[0070] (3) Post-processing:

[0071] The slurry in the reactor was transferred to an aging tank. After the slurry was completely settled, the upper mother liquor was pumped out and a 0.4 mol / L sodium hydroxide solution was added to age it for 8 h. The aged slurry was washed with deionized water and then dried at 110 ° C. After sieving and removing magnetism, the high-tapped high-specificity zinc-doped sodium electric precursor Ni 0.20 Zn 0.10 Fe 0.30 Mn 0.40 (OH)2.

[0072] like Figure 1 Shown is a 10K-fold electron microscope image of the zinc-doped sodium electrode precursor prepared in this example.

[0073] Example 2

[0074] It is basically the same as Example 1, except that: according to the chemical formula Ni 0.264 Zn 0.07 Fe 0.333 Mn 0.333 (OH)2 is used to prepare the metal elements, controlling the molar percentages of nickel, iron, zinc and manganese elements to be 20:10:30:40, and finally obtaining a zinc-doped sodium electric precursor that conforms to the above chemical formula.

[0075] like Figure 2 Shown is a 10K-fold electron microscope image of the zinc-doped sodium electrode precursor prepared in this example.

[0076] Example 3

[0077] It is basically the same as Example 1, except that:

[0078] (2.1) Continuously control the pH of the reaction system in the reactor to 11 and the ammonium concentration to 3.5 g / L;

[0079] (2.2) The pH of the reaction system in the reactor was continuously controlled to be 10.5 and the ammonium concentration to be 2.5 g / L.

[0080] Example 4

[0081] It is basically the same as Example 1, except that:

[0082] (2.1) Continuously control the pH of the reaction system in the reactor to 13 and the ammonium concentration to 5.5 g / L;

[0083] (2.2) The pH of the reaction system in the reactor was continuously controlled to be 11 and the ammonium concentration to be 4 g / L.

[0084] Comparative Example 1

[0085] The method is basically the same as Example 1, except that the addition of sodium gluconate is omitted in step (1).

[0086] like Figure 3 Shown is a 10K-fold electron microscope image of the zinc-doped sodium electrode precursor prepared in this comparative example.

[0087] Comparative Example 2

[0088] The method is substantially the same as Example 1, except that sodium gluconate is replaced with citric acid in step (1); and the following conditions are satisfied:

[0089] (2.1) Continuously controlling the pH of the reaction system in the reactor to be 10.7;

[0090] (2.2) The pH of the reaction system in the reactor was continuously controlled to be 9.8.

[0091] like Figure 4 Shown is a 10K-fold electron microscope image of the zinc-doped sodium electrode precursor prepared in this comparative example.

[0092] Table 1

[0093] <![CDATA[Specific surface area (m 2 / g)]]> <![CDATA[Tap density (g / cm 3 )]]> Example 1 16.15 1.92 Example 2 15.72 1.85 Example 3 16.34 1.81 Example 4 15.28 2.02 Comparative Example 1 11.40 1.87 Comparative Example 2 15.19 1.37

[0094] from Figure 1 to Figure 4 As shown in Table 1, the preparation process of the present invention can obtain a zinc-doped sodium ion battery positive electrode precursor with high specific surface area, high tap compaction, high particle size and good uniformity. It can be understood that the positive electrode precursor of the present invention can be used to obtain a positive electrode with high energy density, strong reaction activity and good cycle stability, and a sodium ion battery with strong electrical performance, which has good application prospects.

[0095] Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing a positive electrode precursor for a zinc-doped sodium ion battery, characterized in that: The steps include: (1) preparing a first solution comprising a nickel salt, a ferrous salt, a manganese salt, a zinc salt, an antioxidant and a first complexing agent; preparing a second solution comprising a precipitant; and preparing a third solution comprising a second complexing agent; wherein the first complexing agent is used for complexing zinc ions and ferrous ions, and the second complexing agent is used for complexing nickel ions and manganese ions; (2) preparing a reaction base liquid; adding the first solution, the second solution and the third solution to the reaction base liquid at 50° C. to 55° C. in an inert gas atmosphere, controlling the pH of the reaction system to be 11 to 13 and the ammonium concentration to be 3 g / L to 6 g / L, and performing a nucleation stage of a coprecipitation reaction; Then, the pH of the reaction system is controlled to be 10.5 to 11 and the ammonium concentration is controlled to be 2 g / L to 4 g / L under continuous feeding, and the growth stage of the coprecipitation reaction is carried out to obtain a precursor material with a particle size of 5 μm to 5.5 μm; (3) Under continuous feeding, the pH of the reaction system is adjusted to 9.8-10.5, and a concentration treatment is performed to obtain a precursor material with a particle size of 9 μm-9.5 μm, and then the inert gas atmosphere is controlled until a precursor material with a particle size of 10±0.2 μm is obtained; then, washing, drying and demagnetization are performed in sequence to obtain a zinc-doped sodium ion battery positive electrode precursor.

2. The method for preparing a positive electrode precursor for a zinc-doped sodium ion battery according to claim 1, characterized in that: In the first solution, the sum of the concentrations of the nickel salt, the ferrous salt, the manganese salt and the zinc salt is 1.0 mol / L to 3.0 mol / L, the concentration of the antioxidant is 0.2 g / L to 1.0 g / L, and the concentration of the first complexing agent is 10 g / L to 20 g / L; Preferably, the ratio of the zinc ions in the zinc salt to the sum of the concentrations is 0.05 to 0.

15.

3. The method for preparing a positive electrode precursor for a zinc-doped sodium ion battery according to claim 1, characterized in that: The antioxidant includes vitamin C, and the first complexing agent includes one of sodium gluconate or EDTA-2Na; and / or, the precipitating agent comprises one of sodium hydroxide or potassium hydroxide; And / or, the second complexing agent includes aqueous ammonia.

4. The method for preparing a positive electrode precursor for a zinc-doped sodium ion battery according to claim 1, characterized in that: In the second solution, the concentration of the precipitant is 6 mol / L to 14 mol / L; And / or, in the third solution, the concentration of the ammonia water is 4 mol / L to 10 mol / L.

5. The method for preparing a positive electrode precursor for a zinc-doped sodium ion battery according to claim 1, characterized in that: The pH of the reaction base solution is 11-13, and the ammonium concentration of the reaction base solution is 3g / L-6g / L.

6. The method for preparing a positive electrode precursor for a zinc-doped sodium ion battery according to claim 1, characterized in that: In the nucleation stage and / or the growth stage, the ratio of the sum of the molar amounts of metal ions of nickel salt, ferrous salt, manganese salt and zinc salt in the first solution to the molar amount of the precipitant is 1:(1.9-2.1); The molar ratio of the sum of the molar amounts of metal ions of nickel salt, ferrous salt, manganese salt and zinc salt in the first solution to the second complexing agent is 1:(0.2-0.4).

7. The method for preparing a positive electrode precursor for a zinc-doped sodium ion battery according to claim 1, characterized in that: The ratio of the flow rate of the first solution in the nucleation stage to the flow rate of the first solution in the growth stage is (1-2):(3-4); Preferably, in the nucleation stage, the flow rate of the first solution is 40 g / min to 80 g / min; in the growth stage, the flow rate of the first solution is 120 g / min to 160 g / min.

8. A zinc-doped sodium ion battery positive electrode precursor, characterized in that: The positive electrode precursor of a zinc-doped sodium ion battery is prepared by the method for preparing the positive electrode precursor of a zinc-doped sodium ion battery as described in any one of claims 1 to 7.

9. A sodium ion battery positive electrode, characterized in that: The positive electrode precursor of the zinc-doped sodium ion battery as claimed in claim 8 is used for preparation.

10. A sodium ion battery, characterized in that: Comprising the sodium ion battery positive electrode as claimed in claim 9.

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