Jackfruit-shaped manganese-rich precursor as well as preparation method and application thereof

Abstract

The invention discloses a jack-fruit-shaped manganese-rich precursor as well as a preparation method and application thereof. The manganese-rich precursor is of a composite multilevel structure, the composite multilevel structure is three-stage particles, the three-stage particles are composed of first-stage particles and second-stage particles jointly, and the second-stage particles are formed by stacking a plurality of first-stage particles and are of a sphere-like structure; the third-stage particles are formed by stacking a plurality of second-stage particles and are of jack-fruit-shaped structures; the specific surface area SSA of the manganese-rich precursor is larger than or equal to 80 and smaller than or equal to 200 m < 2 > / g, and the tap density TD of the manganese-rich precursor is larger than or equal to 1.3 g / cm < 3 >. The manganese-rich precursor has high specific surface area and high tap density at the same time, the change rule that the specific surface area and tap density of the precursor always present opposite changes is broken, and the positive electrode material end prepared from the precursor has higher capacity.

Description

Technical Field

[0001] The invention belongs to the technical field of sodium ion batteries, and particularly relates to a jackfruit-shaped manganese-rich precursor and a preparation method and application thereof. Background Art

[0002] Since the successful commercialization of lithium-ion batteries (LIBs), they have been widely used in portable electronic devices, electric vehicles (EVs), and electrochemical energy storage. However, due to the relatively low abundance and geographically concentrated availability of lithium resources, lithium resources cannot well meet the growing demand for electrochemical energy storage, resulting in a rapid increase in the price of lithium compounds. In this context, sodium-ion batteries (SIBs) have attracted widespread attention due to the high abundance and uniform geographical distribution of sodium resources. More importantly, due to the similar chemical properties of lithium and sodium, SIBs exhibit similar working principles to LIBs. Therefore, SIBs have become a very promising alternative to LIBs, especially in electrochemical energy storage devices, among which layered oxides are one of the most competitive SIB cathode materials due to their high energy density, rich variety, and simple synthesis process. According to the definition proposed by Delmas et al., layered oxides can be divided into two common types: P2 type (ABBA stacking mode, Na+ occupies trigonal prism positions) and O3 type (ABCABC stacking mode, Na+ occupies octahedral positions). However, both P2-type and O3-type layered transition metal oxides have phase change problems during the charge and discharge process, which will lead to their capacity decay. However, because the P2-type structure has a more stable and open framework and undergoes fewer multiphase transitions during the charge / discharge process, P2-type layered oxides generally show better cycle stability and rate performance than O3-type layered oxides. However, the P2-type sodium positive electrode generally has a lower capacity than the O3 type, making it difficult to use in power batteries, making it difficult to increase its scale of use and value. And P2-Na0.67Ni x Mn 1-x O2(x<0.4)(NMO) shows a high discharge specific capacity. This component has a higher discharge capacity and a higher platform voltage due to the use of a high manganese system, thus having a higher energy density. It also takes into account the excellent cycle performance of P2-type sodium battery materials, and has attracted great attention in the industry.

[0003] The manganese-rich precursor was prepared by coprecipitation and then P2-Na0.67Ni was further prepared. x Mn 1-x O2(x<0.4)(NMO) is a relatively mature preparation method that is relatively easy to implement in large-scale production. This method can achieve uniform mixing at the atomic level, has simple equipment, is easy to operate, and can control the particle size and morphology of the product.

[0004] At present, manganese-rich precursors are usually prepared by carbonate and hydroxide co-precipitation technology routes. When the carbonate process is used, the precursor is easy to form a relatively round secondary sphere, but the decomposition rate of carbonate is high, resulting in large internal pores in the secondary spheres of the sintered material, affecting the tap density of the material and the specific energy of the battery. In addition, in the carbonate co-precipitation system, due to the large precipitation equilibrium constant of Ni, the precipitation is incomplete, causing the loss of Ni elements, and ultimately resulting in increased costs on the raw material side. Moreover, the secondary spheres are easily crushed under high compaction density, causing the pole pieces to pulverize and fail. When a hydroxide precursor process similar to ternary materials is used, due to the high manganese content in the manganese-rich precursor, the conventional ammonia-complexation-inert atmosphere process system is used for preparation, and the primary particles are large and thick sheets. Such large primary sheets are difficult to agglomerate together to form uniform and dense secondary spheres, so the hydroxide process is not easy to form balls, resulting in low tap density and specific surface area of ​​the precursor, affecting the tap and compaction density and processing performance of the material, and thus affecting the volume energy density of the battery. Moreover, such large thick flake primary particles have low activity during sintering, requiring a higher sintering temperature. The primary particles of the sintered material are also large, which is not conducive to the electrochemical activity of the material. Therefore, compared with carbonate precursors, the electrochemical properties of the sintered material of the manganese-rich precursor synthesized by the hydroxide-coprecipitation route are generally significantly lower. Therefore, the current mainstream route is to improve the tap density, specific surface area and sintering activity of the precursor by modifying and refining the primary particles in the hydroxide-coprecipitation process.

[0005] For example, the patent with publication number CN116022863A discloses a method of preparing a high manganese precursor with fluffy primary particles by cooling or lowering pH. Although this solution can refine the primary particles, it has high requirements on the equipment. When the reaction temperature is lower than 40°C, cooling circulating water needs to be introduced, which is not conducive to expanding the production capacity. In addition, the crystallinity of the precursor synthesized at low temperature is poor. The primary particles will thicken after alkali washing, and the improvement of the specific surface area and the sintering activity of the primary particles is limited; the patent with publication number CN116768287A discloses a method of preparing a high manganese precursor with thin primary particles by introducing an organic chelating agent. Although this solution can refine the primary particles, improve the sintering activity and thus improve the electrochemical performance, the use of an organic chelating agent will increase the cost of the back-end sewage treatment, which is not conducive to expanding the production capacity; the patent with publication number CN115124089A discloses a method of preparing a manganese-rich precursor with a honeycomb structure by an oxidation process, but its specific surface area improvement is limited (<60m 2 / g), and due to the large voids, the tap density of the precursor is also low (<1.4g / cc), resulting in a low compaction density of the sintered material, which is not conducive to the back-end application of positive electrode materials. Studies have shown that the tap density and specific surface area of ​​the precursor are the factors affecting the performance of P2-Na0.67Ni x Mn 1-xO2(x<0.4)(NMO) is an important factor in the electrochemical performance of positive electrode materials. Co-precipitation is currently the main method for preparing manganese-rich precursors. However, it is currently difficult to prepare manganese-rich precursors with suitable specific surface area and tap density using the co-precipitation method. The specific surface area and tap density of the precursor always show opposite changes, and it is impossible to take into account both high specific surface area and tap density. If a hydroxide-co-precipitation process is used, and organic complexing agents and low temperatures are used to refine the primary particles, this type of modification scheme is difficult to industrialize and has high costs. For a simple oxidation process, it is difficult for various physical and chemical indicators in the precursor to meet the requirements, which is a problem for P2-Na0.67Ni x Mn 1-x The industrial application of O2 (x<0.4) (NMO) brings resistance. Therefore, it is particularly important to further shorten the primary particle size, improve the specific surface and compaction, and improve the sintering activity without increasing the cost. Summary of the invention

[0006] The main purpose of the present invention is to provide a jackfruit-shaped manganese-rich precursor and a preparation method and application thereof, so as to overcome the shortcomings of the prior art.

[0007] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0008] The embodiment of the present invention provides a jackfruit-shaped manganese-rich precursor, wherein the manganese-rich precursor has a composite multi-level structure, wherein the composite multi-level structure is a three-level particle, wherein the three-level particle is composed of a primary particle and a secondary particle, wherein the secondary particle is formed by stacking a plurality of primary particles and presents a spherical structure; wherein the three-level particle is formed by stacking a plurality of secondary particles and presents a jackfruit-shaped structure; wherein the specific surface area SSA of the manganese-rich precursor satisfies: 80≤SSA≤200m 2 / g, the tap density TD of the manganese-rich precursor satisfies: TD≥1.3g / cm 3 .

[0009] The embodiment of the present invention further provides a method for preparing the aforementioned jackfruit-shaped manganese-rich precursor, which comprises:

[0010] A mixed reaction system including at least nickel salt, manganese salt, precipitant, sodium sulfate and oxidant is subjected to a coprecipitation reaction to obtain a jackfruit-shaped manganese-rich precursor.

[0011] The embodiment of the present invention also provides the use of the aforementioned jackfruit-shaped manganese-rich precursor in the preparation of a sodium battery positive electrode material or a sodium ion battery.

[0012] The present invention also provides a method for preparing a positive electrode material for a sodium battery, which comprises:

[0013] The aforementioned jackfruit-shaped manganese-rich precursor is mixed with a sodium salt to form a sintering precursor;

[0014] Furthermore, the sintered precursor is calcined at 800-950° C. for 12-24 hours, and then crushed and sieved to obtain a positive electrode material for a sodium battery.

[0015] The embodiment of the present invention also provides a sodium battery positive electrode material prepared by the aforementioned preparation method.

[0016] An embodiment of the present invention further provides a sodium ion battery, which at least comprises the aforementioned sodium battery positive electrode material.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The present invention uses an oxidation process to refine the thickness of the primary particles, increase the sodium sulfate concentration, and increase the supersaturation of metal ions in the solution, thereby shortening the length of the primary particles, so that the secondary particles with larger size are stacked to form the final tertiary particles. This structure has a higher specific surface area (>80m 2 / g) and has a higher tap density (>1.4g / cc), breaking the law that the specific surface area and tap density of the precursor always show opposite changes. The higher specific surface area is conducive to the better penetration and fusion of lithium salt with the precursor during sintering. The higher tap density ensures the loading amount and compaction density of the back-end material during sintering. The shorter and finer primary particles can greatly improve the sintering activity of the sintering end, making the capacity release more complete after sintering, and the positive electrode material end has a higher capacity;

[0019] (2) The preparation process provided by the present invention is based on the traditional oxidation process with the addition of an additive (sodium sulfate solution). The process does not introduce an organic complexing agent or impurity elements, and the conventional reaction conditions of temperature > 40° C. do not increase costs and have low equipment requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in 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 This is a 10,000-fold scanning electron microscope image of the manganese-rich precursor of Example 1 of the present invention;

[0022] Figure 2 This is a 50,000-fold scanning electron microscope image of the manganese-rich precursor of Example 1 of the present invention;

[0023] Figure 3 This is a 10,000-fold scanning electron microscope image of the manganese-rich precursor of Comparative Example 1 of the present invention;

[0024] Figure 4 This is a 50,000-fold scanning electron microscope image of the manganese-rich precursor of Comparative Example 1 of the present invention;

[0025] Figure 5 This is a 10,000-fold scanning electron microscope image of the manganese-rich precursor of Comparative Example 2 of the present invention;

[0026] Figure 6 This is a 50,000-fold scanning electron microscope image of the manganese-rich precursor of Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0027] In view of the defects of the prior art, the inventor of this case has proposed the technical solution of the present invention after long-term research and extensive practice. The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Specifically, as one aspect of the technical solution of the present invention, a jackfruit-shaped manganese-rich precursor involved therein has a composite multi-level structure, wherein the composite multi-level structure is a three-level particle, wherein the three-level particle is composed of a primary particle and a secondary particle, wherein the secondary particle is formed by stacking a plurality of primary particles and presents a spherical structure; wherein the three-level particle is formed by stacking a plurality of secondary particles and presents a jackfruit-shaped structure; wherein the specific surface area SSA of the manganese-rich precursor satisfies: 80≤SSA≤200m 2 / g, the tap density TD of the manganese-rich precursor satisfies: TD≥1.3g / cm 3 .

[0029] In some preferred embodiments, the specific surface area SSA of the manganese-rich precursor satisfies: 100 ≤ SSA ≤ 170 m 2 / g.

[0030] In some preferred embodiments, the tap density TD of the manganese-rich precursor satisfies: TD ≥ 1.4 g / cm 3 .

[0031] In some preferred embodiments, the particle size D50 of the tertiary particles satisfies: 5 μm≤D50≤15 μm.

[0032] Furthermore, the particle size D50 of the tertiary particles satisfies: 7 μm≤D50≤13 μm.

[0033] In some preferred embodiments, the diameter d of the secondary particles satisfies: 200nm≤d≤400nm.

[0034] Furthermore, the diameter d of the secondary particles satisfies: 250nm≤d≤350nm.

[0035] In some preferred embodiments, the length x of the primary particle satisfies: 30 nm ≤ x ≤ 200 nm.

[0036] Furthermore, the length x of the primary particle satisfies: 80nm≤x≤150nm.

[0037] In some preferred embodiments, the chemical formula of the manganese-rich precursor is Ni a Mn b (OH)2, wherein a+b=1, 0.2≤a≤0.5, 0.5≤b≤0.9.

[0038] Another aspect of the embodiments of the present invention further provides a method for preparing the aforementioned jackfruit-shaped manganese-rich precursor, which comprises:

[0039] A mixed reaction system including at least nickel salt, manganese salt, inorganic complexing agent, precipitant, sodium sulfate and oxidant is subjected to a coprecipitation reaction to obtain a jackfruit-shaped manganese-rich precursor.

[0040] In some preferred embodiments, the preparation method specifically comprises:

[0041] Preparing a mixed salt solution including nickel salt and manganese salt, a precipitant solution and a sodium sulfate solution;

[0042] Furthermore, the mixed salt solution, the precipitant solution, the inorganic complexing agent, the sodium sulfate solution and the oxidant are input into a reaction device and subjected to a coprecipitation reaction at a rotation speed of 500 to 1000 r / min, a temperature of 40 to 60° C. and a pH value of 10.5 to 12.3 to obtain a jackfruit-shaped manganese-rich precursor.

[0043] Further, the nickel salt includes any one or more combinations of nickel sulfate, nickel chloride, nickel acetate, and nickel nitrate, but is not limited thereto.

[0044] Furthermore, the manganese salt includes any one or more combinations of manganese sulfate, manganese chloride, manganese acetate, and manganese nitrate, but is not limited thereto.

[0045] Furthermore, the inorganic complexing agent includes any one or more combinations of ammonia water, ammonium sulfate, ammonium chloride, ammonium acetate, and ammonium nitrate, but is not limited thereto.

[0046] Further, the precipitant includes sodium hydroxide and / or potassium hydroxide, but is not limited thereto.

[0047] Further, the oxidant includes any one or more combinations of potassium permanganate, perchloric acid, hypochlorous acid, hydrogen peroxide, sodium hypochlorite, potassium persulfate, sodium persulfate, ammonium persulfate, air, and oxygen, but is not limited thereto.

[0048] Furthermore, the molar ratio of the sum of the nickel salt and the manganese salt, the precipitant, the inorganic complexing agent and the sodium sulfate is 10:20:0.3-3:10-20.

[0049] The preparation process of the manganese-rich precursor in the present invention is an oxidation process, which defines the Mn entering per unit time. 2+ The total amount is completely oxidized to Mn 4+ The degree of oxidation is 100% (the amount of oxidant participating in the reaction per unit time and the amount of Mn per unit time 2+ The degree of oxidation was calculated based on the molar ratio of the inflow amount).

[0050] Furthermore, the oxidation degree of the manganese-rich precursor is 5% to 80%.

[0051] Furthermore, the oxidation degree of the manganese-rich precursor is 40% to 70%.

[0052] The present invention introduces sodium sulfate solution to increase the ion concentration in the solution. Although sodium sulfate can also be produced in the feed, the maximum concentration of the metal salt is 3 mol / L, and the sulfate radicals provided by it are limited, and the increase in the sodium sulfate concentration is also limited. Therefore, increasing the feed of sodium sulfate alone can further increase the Na+ content in the solution. + and SO4 2- Concentration, higher ion concentration will further increase the saturation of ions in the solution, promote the reaction rate of metal cations and precipitants to increase, increase the nucleation rate, thereby generating secondary nucleation on the surface of the precursor, thereby shortening the primary particle size, and combining with the oxidant (oxidation makes the primary particles thinner), and finally generating thin and short needle-shaped primary particles; and the traditional way of increasing the nucleation rate by increasing the pH is combined with the oxidation process, because the oxidation process will passivate the functional groups on the surface of the precursor, and the supersaturation is proportional to the square of the hydroxide concentration, making the nucleation rate control extremely harsh, which is very likely to cause serious seeding problems, and the precursor particle size cannot rise, which eventually leads to the failure of the precursor's physical and chemical indicators to meet the standards, and the present invention does not cause seeding problems by increasing the concentration of sodium sulfate in the solution, and the sodium sulfate can be recycled and reused through the later wastewater, which will not cause cost increases. Another aspect of the embodiment of the present invention also provides the use of the aforementioned jackfruit-shaped manganese-rich precursor in the preparation of sodium battery positive electrode materials or sodium ion batteries.

[0053] Another aspect of the embodiments of the present invention further provides a method for preparing a positive electrode material for a sodium battery, which comprises:

[0054] The aforementioned jackfruit-shaped manganese-rich precursor is mixed with a sodium salt to form a sintering precursor;

[0055] Furthermore, the sintered precursor is calcined at 800-950° C. for 12-24 hours, and then crushed and sieved to obtain a positive electrode material for a sodium battery.

[0056] In some preferred embodiments, the sodium salt includes any one or more combinations of anhydrous sodium carbonate, sodium carbonate monohydrate, sodium carbonate decahydrate, sodium bicarbonate, and sodium sulfate, but is not limited thereto.

[0057] Furthermore, any one or more combinations of anhydrous sodium carbonate, sodium bicarbonate, and sodium sulfate are particularly preferred, but are not limited thereto.

[0058] In some preferred embodiments, the calcination temperature is 850-900°C.

[0059] In some preferred embodiments, the calcination treatment time is 12-20 hours.

[0060] In some preferred embodiments, the atmosphere used in the calcination process includes air and / or oxygen, but is not limited thereto.

[0061] Furthermore, the atmosphere used in the calcination treatment is air.

[0062] In some preferred embodiments, the molar ratio of the manganese-rich precursor to the sodium salt is 1:1 to 1:1.1.

[0063] Furthermore, the molar ratio of the manganese-rich precursor to the sodium salt is 1:1.03-1.07.

[0064] In some more specific embodiments, the preparation method of the sodium battery positive electrode material (high temperature solid phase method) includes:

[0065] The required sodium salt of 100wt%-110wt% of the stoichiometric amount of Na (preferably 103wt%-107wt%) and the aforementioned manganese-rich precursor are mixed into a sintering precursor by a mechanical mixing device.

[0066] In particular, the sodium salt may be one or more of anhydrous sodium carbonate, sodium carbonate monohydrate, sodium carbonate decahydrate, sodium bicarbonate, and sodium sulfate; (preferably, one or more of anhydrous sodium carbonate, sodium bicarbonate, and sodium sulfate).

[0067] The sintered precursor is placed in a sintering device and calcined at high temperature for 12 to 24 hours (preferably 12 to 20 hours) to obtain a positive electrode material. In particular, the high temperature calcination temperature is 800 to 950° C. (preferably 850 to 900° C.), and the high temperature calcination atmosphere is one or more of air and oxygen (preferably air).

[0068] After high temperature calcination, the positive electrode material is crushed by crushing equipment and then sieved to obtain the positive electrode material. In particular, the crushing equipment is one or more of a roller mill, a ball mill, a mortar mill, and a jet mill.

[0069] The mechanical mixing equipment is one of a ball mill, a three-dimensional mixer, a high-speed mixer, and a VC mixer.

[0070] Another aspect of the embodiments of the present invention further provides a sodium battery positive electrode material prepared by the aforementioned preparation method.

[0071] Another aspect of an embodiment of the present invention further provides a sodium ion battery, which at least comprises the aforementioned sodium battery positive electrode material.

[0072] The technical solution of the present invention is further described in detail below in conjunction with several preferred embodiments and drawings. This embodiment is implemented on the premise of the technical solution of the invention, and a detailed implementation method and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

[0073] Unless otherwise specified, the experimental materials used in the following examples can be purchased from conventional biochemical reagent companies.

[0074] Example 1

[0075] (1) According to the molar ratio of Ni:Mn=35:65, NiSO4·6H2O and MnSO4·H2O were weighed and dissolved in deionized water to prepare a 2 mol / L mixed salt solution A; then Na2SO4 was prepared into a 3 mol / L solution B, and at the same time, 10 mol / L sodium hydroxide solution was prepared as a precipitant, 5 mol / L ammonia water was prepared as a complexing agent, and oxygen was prepared as an oxidant;

[0076] (2) The prepared solution A, solution B, sodium hydroxide aqueous solution, ammonia water and oxygen were introduced into a reaction kettle in a volume ratio of 10:10:4:1.5:100, and the pH was controlled at 11.5±0.1, the temperature was 50°C, and the rotation speed was 1000 r / min to form a reaction slurry. When D50 grew to 11 μm, the reaction was stopped to obtain a manganese-rich precursor. The scanning electron microscope image of the manganese-rich precursor at 10,000 times was as shown in FIG. Figure 1 As shown, the 50,000x scanning electron microscope image is as follows Figure 2 shown.

[0077] Example 2

[0078] (1) According to the molar ratio of Ni:Mn=35:65, NiSO4·6H2O and MnSO4·H2O were weighed and dissolved in deionized water to prepare a 2 mol / L mixed salt solution A; then Na2SO4 was prepared into a 3 mol / L solution B, and at the same time, 10 mol / L sodium hydroxide solution was prepared as a precipitant, 5 mol / L ammonia water was prepared as a complexing agent, and 30%wt hydrogen peroxide was prepared as an oxidant;

[0079] (2) The prepared solution A, solution B, sodium hydroxide aqueous solution, ammonia water and hydrogen peroxide solution were introduced into a reaction kettle in a volume ratio of 10:10:4:1.5:7, and the pH was controlled at 11.5±0.1, the temperature was 50°C, and the rotation speed was 1000 r / min to form a reaction slurry. When D50 grew to 11 μm, the reaction was stopped to obtain a manganese-rich precursor.

[0080] Example 3

[0081] (1) According to the molar ratio of Ni:Mn=45:55, NiSO4·6H2O and MnSO4·H2O were weighed and dissolved in deionized water to prepare a 2 mol / L mixed salt solution A; then Na2SO4 was prepared into a 2.5 mol / L solution B, and 10 mol / L sodium hydroxide solution was prepared as a precipitant, 5 mol / L ammonia water was prepared as a complexing agent, and air was used as an oxidant;

[0082] (2) The prepared solution A, solution B, sodium hydroxide aqueous solution, ammonia water and air were introduced into a reaction kettle at a volume ratio of 10:10:4:1.5:280, and the pH was controlled at 11.2±0.1, the temperature was 60°C, and the rotation speed was 1000 r / min to form a reaction slurry. When D50 grew to 11 μm, the reaction was stopped to obtain a manganese-rich precursor.

[0083] Example 4

[0084] (1) According to the molar ratio of Ni:Mn=10:90, NiSO4·6H2O and MnSO4·H2O were weighed and dissolved in deionized water to prepare a 2.0 mol / L mixed salt solution A; then Na2SO4 was prepared into a 3 mol / L solution B, and at the same time, 10 mol / L sodium hydroxide solution was prepared as a precipitant, 5 mol / L ammonia water was prepared as a complexing agent, and oxygen was prepared as an oxidant;

[0085] (2) The prepared solution A, solution B, sodium hydroxide aqueous solution, ammonia water and oxygen were introduced into a reaction kettle in a volume ratio of 10:10:4:1.5:70, and the pH was controlled at 11.2±0.1, the temperature was 50°C, and the rotation speed was 1000 r / min to form a reaction slurry. When D50 grew to 11 μm, the reaction was stopped to obtain a manganese-rich precursor.

[0086] The preparation method of Examples 5-10 is the same as the preparation method of Examples 1-4, the only difference being that the precursor structure is regulated by changing the oxidation degree and the concentration of the sodium sulfate solution as shown in Table 1, and the component ratio is changed as shown in Table 2.

[0087] Comparative Example 1

[0088] (1) According to the molar ratio of Ni:Mn=35:65, NiSO4·6H2O and MnSO4·H2O were weighed and dissolved in deionized water to prepare a 2 mol / L mixed salt solution A; at the same time, 10 mol / L sodium hydroxide solution was prepared as a precipitant, 5 mol / L ammonia water was prepared as a complexing agent, and nitrogen was introduced as a protective gas;

[0089] (2) The prepared solution A, sodium hydroxide aqueous solution and ammonia water were introduced into a reaction kettle at a volume ratio of 10:4:1.5, and the pH was controlled at 11.5±0.1, the temperature was 50°C, and the rotation speed was 1000 r / min to form a reaction slurry. When D50 grew to 11 μm, the reaction was stopped to obtain a manganese-rich precursor. The scanning electron microscope image of the manganese-rich precursor at 10,000 times was as shown in FIG. Figure 3 As shown, the 50,000x scanning electron microscope image is as follows Figure 4 shown.

[0090] Comparative Example 2

[0091] (1) According to the molar ratio of Ni:Mn=35:65, NiSO4·6H2O and MnSO4·H2O were weighed and dissolved in deionized water to prepare a 2 mol / L mixed salt solution A; at the same time, 10 mol / L sodium hydroxide solution was prepared as a precipitant, 5 mol / L ammonia water was prepared as a complexing agent, and oxygen was prepared as an oxidant;

[0092] (2) The prepared solution A, sodium hydroxide aqueous solution, ammonia water and oxygen were introduced into a reaction kettle in a volume ratio of 10:4:1.5:100, and the pH was controlled at 11.5±0.1, the temperature was 50°C, and the rotation speed was 1000 r / min to form a reaction slurry. When D50 grew to 11 μm, the reaction was stopped to obtain a manganese-rich precursor. The scanning electron microscope image of the manganese-rich precursor at 10,000 times was as shown in FIG. Figure 5 As shown, the 50,000x scanning electron microscope image is as follows Figure 6 shown.

[0093] Comparative Example 3

[0094] (1) According to the molar ratio of Ni:Mn=35:65, NiSO4·6H2O and MnSO4·H2O were weighed and dissolved in deionized water to prepare a 2 mol / L mixed salt solution A, and then Na2SO4 was prepared into a 3 mol / L solution B. At the same time, 10 mol / L sodium hydroxide solution was prepared as a precipitant and 5 mol / L ammonia water was prepared as a complexing agent;

[0095] (2) The prepared solution A, solution B, sodium hydroxide aqueous solution, and ammonia water were introduced into the reaction kettle in a volume ratio of 10:10:4:1.5, and the pH was controlled at 11.5±0.1, the temperature was 50°C, and the rotation speed was 1000 r / min to form a reaction slurry. When D50 grew to 11 μm, the reaction was stopped.

[0096] Comparative Example 4

[0097] 1) According to the molar ratio of Ni:Mn=35:65, NiSO4·6H2O and MnSO4·H2O were weighed and dissolved in deionized water to prepare a 2 mol / L mixed salt solution A, and then Na2SO4 was prepared into a 3 mol / L solution B. At the same time, 10 mol / L sodium hydroxide solution was prepared as a precipitant, 5 mol / L ammonia water was prepared as a complexing agent, and oxygen was used as an oxidant (the amount of oxygen was insufficient);

[0098] (2) The prepared solution A, solution B, sodium hydroxide aqueous solution, and ammonia water are introduced into the reaction kettle in a volume ratio of 10:10:4:1.5:40, and the pH is controlled at 11.5±0.1, the temperature is 50°C, and the speed is 1000r / min to form a reaction slurry. When D50 grows to 11μm, the reaction is stopped. The precursor materials prepared in the above Examples 1-10 and Comparative Examples 1-4 are used to prepare positive electrode materials for sodium ion batteries. The preparation method is as follows:

[0099] 1000 g of the precursor material prepared in Examples 1-10 and Comparative Examples 1-4 was mixed evenly with Na2CO3 in a molar ratio of 1:1.03 by a high-speed mixer, and sintered in a box furnace under an air atmosphere at a sintering temperature of 900°C for 12 h. After cooling to room temperature, the mixture was crushed and sieved to obtain a layered oxide positive electrode material.

[0100] The positive electrode active material prepared above was dispersed in NMP solvent with PVDF and conductive carbon in a mass ratio of 90:5:5, coated on an aluminum foil current collector and dried to form a positive electrode sheet, and then the positive electrode sheet, sodium sheet, glass fiber separator, gasket, reed sheet, and NaPF6-DIGLYME electrolyte were made into a button battery according to the button battery assembly standard operation process. The charge and discharge curve at 2.0-4.3V 0.1C rate was obtained through the Xinwei detection channel detection.

[0101] The precursor structures provided by the above-mentioned Examples 1-10 and Comparative Examples 1-4 are shown in Table 1; the elemental composition and content, porosity, specific surface area, and tap density of the precursors are shown in Table 2; the electrochemical properties of the precursor materials provided by Examples 1-10 and Comparative Examples 1-4 are shown in Table 3.

[0102] Table 1 Different reaction conditions of precursors in Examples 1-10 and Comparative Examples 1-4

[0103]

[0104]

[0105] Table 2 Component ratio, specific surface area, and tap density of precursor materials of Examples 1-10 and Comparative Examples 1-4

[0106] name Ni∶Mn <![CDATA[BET(m 3 / g)]]> <![CDATA[TD(g / cm 3 )]]> Example 1 0.35∶0.65 154 1.63 Example 2 0.35∶0.65 132 1.54 Example 3 0.35∶0.65 104 1.41 Example 4 0.45∶0.55 117 1.53 Example 5 0.10∶0.90 136 1.49 Example 6 0.20∶0.80 143 1.58 Example 7 0.30∶0.70 123 1.44 Example 8 0.40∶0.60 129 1.50 Example 9 0.35∶0.65 135 1.55 Example 10 0.35∶0.65 162 1.59 Comparative Example 1 0.35∶0.65 12 1.81 Comparative Example 2 0.35∶0.65 14 1.71 Comparative Example 3 0.35∶0.65 87 1.24 Comparative Example 4 0.35∶0.65 28 1.05

[0107] Table 3 Electrochemical performance of positive electrode materials prepared from precursors of Examples 1-10 and Comparative Examples 1-4 in batteries

[0108]

[0109]

[0110] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments with other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0111] It should be understood that the technical solution of the present invention is not limited to the above-mentioned specific implementation cases. Any technical deformation made according to the technical solution of the present invention without departing from the scope of protection of the purpose of the present invention and the claims shall fall within the protection scope of the present invention.

Claims

1. A jackfruit-shaped manganese-rich precursor, characterized in that: The manganese-rich precursor has a composite multi-level structure, which is a three-level particle. The three-level particle is composed of a primary particle and a secondary particle. The secondary particle is formed by stacking a plurality of primary particles and has a spherical structure. The three-level particle is formed by stacking a plurality of secondary particles and has a jackfruit-like structure. The specific surface area SSA of the manganese-rich precursor satisfies: 80≤SSA≤200m 2 / g, the tap density TD of the manganese-rich precursor satisfies: TD≥1.3g / cm 3 .

2. The manganese-rich precursor according to claim 1, characterized in that: The specific surface area SSA of the manganese-rich precursor satisfies: 100≤SSA≤170m 2 / g And / or, the tap density TD of the manganese-rich precursor satisfies: TD ≥ 1.4 g / cm 3 ; And / or, the particle size D50 of the tertiary particles satisfies: 5 μm≤D50≤15 μm, preferably 7 μm≤D50≤13 μm; And / or, the diameter d of the secondary particles satisfies: 200nm≤d≤400nm, preferably 250nm≤d≤350nm; And / or, the length x of the primary particles satisfies: 30 nm≤x≤200 nm, preferably 80 nm≤x≤150 nm.

3. The manganese-rich precursor according to claim 1, characterized in that: The chemical formula of the manganese-rich precursor is Ni a Mn b (OH)2, wherein a+b=1, 0.2≤a≤0.5, 0.5≤b≤0.

9.

4. The method for preparing the jackfruit-shaped manganese-rich precursor according to any one of claims 1 to 3, characterized in that: include: A mixed reaction system including at least nickel salt, manganese salt, inorganic complexing agent, precipitant, sodium sulfate and oxidant is subjected to a coprecipitation reaction to obtain a jackfruit-shaped manganese-rich precursor.

5. The preparation method according to claim 4, characterized in that: Specifically include: Preparing a mixed salt solution including nickel salt and manganese salt, a precipitant solution and a sodium sulfate solution; Furthermore, the mixed salt solution, the precipitant solution, the inorganic complexing agent, the sodium sulfate solution and the oxidant are input into a reaction device and subjected to a coprecipitation reaction at a rotation speed of 500 to 1000 r / min, a temperature of 40 to 60° C. and a pH value of 10.5 to 12.3 to obtain a jackfruit-shaped manganese-rich precursor.

6. The preparation method according to claim 5, characterized in that: The nickel salt includes any one or more combinations of nickel sulfate, nickel chloride, nickel acetate, and nickel nitrate; And / or, the manganese salt includes any one or more combinations of manganese sulfate, manganese chloride, manganese acetate, and manganese nitrate; And / or, the inorganic complexing agent includes any one or more combinations of ammonia water, ammonium sulfate, ammonium chloride, ammonium acetate, and ammonium nitrate; and / or, the precipitating agent comprises sodium hydroxide and / or potassium hydroxide; And / or, the oxidant includes any one or more combinations of potassium permanganate, perchloric acid, hypochlorous acid, hydrogen peroxide, sodium hypochlorite, potassium persulfate, sodium persulfate, ammonium persulfate, air, and oxygen; and / or, the molar ratio of the sum of the nickel salt and the manganese salt, the precipitant, the inorganic complexing agent and the sodium sulfate is 10:20:0.3-3:10-20; And / or, the oxidation degree of the manganese-rich precursor is 5% to 80%, preferably 40% to 70%.

7. Use of the jackfruit-shaped manganese-rich precursor according to any one of claims 1 to 3 in preparing a positive electrode material for a sodium battery or a sodium ion battery.

8. A method for preparing a positive electrode material for a sodium battery, characterized in that: include: Mixing the jackfruit-shaped manganese-rich precursor according to any one of claims 1 to 3 with a sodium salt to form a sintering precursor; and calcining the sintered precursor at 800-950° C. for 12-24 hours, and then crushing and screening to obtain a positive electrode material for a sodium battery; Preferably, the sodium salt includes any one or more combinations of anhydrous sodium carbonate, sodium carbonate monohydrate, sodium carbonate decahydrate, sodium bicarbonate, and sodium sulfate, and is particularly preferably any one or more combinations of anhydrous sodium carbonate, sodium bicarbonate, and sodium sulfate; Preferably, the calcination temperature is 850-900°C; preferably, the calcination time is 12-20h; Preferably, the atmosphere used in the calcination treatment includes air and / or oxygen, and air is particularly preferred; Preferably, the molar ratio of the manganese-rich precursor to the sodium salt is 1:1 to 1:1.1, and particularly preferably 1:1.03 to 1.

07.

9. A sodium battery positive electrode material prepared by the preparation method according to claim 8.

10. A sodium ion battery, characterized in that: At least comprising the sodium battery positive electrode material according to claim 9.

Images