Preparation method of nitrogen-doped vanadium dioxide positive electrode active material, positive electrode active material and battery

Abstract

The application provides a preparation method of a nitrogen-doped vanadium dioxide positive electrode active material, a positive electrode active material and a battery. The method comprises the following steps: mixing a vanadium source, lysine and water, and performing a hydrothermal reaction after adjusting pH. In the hydrothermal reaction process, the amino group in the lysine is used as a reducing agent to reduce the vanadium source into vanadium dioxide, and meanwhile, the nitrogen element in the lysine is doped into the vanadium dioxide crystal lattice in situ, so that the nitrogen-doped vanadium dioxide positive electrode active material is obtained. The method does not need to add a reducing agent and a nitrogen-containing polymer additionally, and does not need high-temperature calcination, so that the process is simplified, and energy consumption is reduced. The obtained material is uniformly doped with nitrogen, has good conductivity and cycle stability, and when the material is applied to an electrochemical device as a positive electrode active material, the material can provide stable capacity output and a long cycle life.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a method for preparing a nitrogen-doped vanadium dioxide positive electrode active material, the positive electrode active material, and the battery. Background Technology

[0002] Vanadium oxides have been extensively studied as cathode materials in aqueous multivalent metal-ion batteries due to their diverse valence states, stable tunnel structures, and abundant resources. However, almost all vanadium oxides share the common problem of poor intrinsic conductivity, which limits their rate performance and cycle stability.

[0003] To improve the conductivity of vanadium oxide, existing technologies mainly employ the following methods: (1) composite with highly conductive carbon materials, (2) doping with high-valence metal ions, (3) preparing nanostructures, and (4) inserting conductive polymers. However, these methods all have significant shortcomings: carbon composites often require high-temperature processing, which can easily damage the integrity of the crystal lattice; metal ion doping has a limited effect on improving conductivity and may introduce impurity phases; nanostructures are prone to agglomeration, resulting in low tap density; and conductive polymer intercalation suffers from poor structural stability due to its large molecular size and insufficient rigidity, making it prone to swelling or deintercalation during long-term cycling.

[0004] In addition to the problems inherent in the aforementioned material modification methods, existing preparation processes also face challenges. Currently, the preparation of nitrogen-doped vanadium dioxide mostly employs electrospinning combined with high-temperature calcination, and the reducing agent and dopant source (such as a nitrogen source) are added separately, resulting in long process flows, high energy consumption, and high costs. The conductivity and cycle stability of the obtained materials still cannot meet the requirements of practical applications. Summary of the Invention

[0005] In view of this, in order to solve at least one of the above-mentioned technical problems, this application needs to provide a method for preparing nitrogen-doped vanadium dioxide positive electrode active material.

[0006] In addition, this application also provides a positive electrode active material prepared by the aforementioned preparation method and a battery using the positive electrode active material.

[0007] In a first aspect, this application provides a method for preparing nitrogen-doped vanadium dioxide material, comprising: mixing a vanadium source, lysine and water, adjusting the pH and carrying out a hydrothermal reaction; during the hydrothermal reaction, the amino group in the lysine acts as a reducing agent to reduce the vanadium source to vanadium dioxide, and simultaneously, the nitrogen element in the lysine is in situ doped into the vanadium dioxide lattice to obtain a reaction product, which is the nitrogen-doped vanadium dioxide positive electrode active material.

[0008] Based on the first aspect, in some embodiments of this application, the molar mass ratio of the lysine to the vanadium element in the vanadium source is 1:2 to 1:4.

[0009] Based on the first aspect, in some embodiments of this application, the vanadium source includes at least one of vanadium pentoxide and ammonium metavanadate.

[0010] Based on the first aspect, in some embodiments of this application, the temperature of the hydrothermal reaction is 160°C to 200°C, and the time is 18h to 36h.

[0011] Based on the first aspect, in some embodiments of this application, the pH value is 2 to 4.

[0012] Based on the first aspect, in some embodiments of this application, the stirring frequency for mixing the vanadium source, lysine and water is 1200 rpm to 2000 rpm, and the stirring time is 120 min to 180 min.

[0013] Based on the first aspect, in some embodiments of this application, after the hydrothermal reaction step, the method further includes: washing and drying the reaction product, wherein the drying is vacuum drying at a temperature of 60°C to 80°C.

[0014] Secondly, this application provides a positive electrode active material, which is prepared by the preparation method described above.

[0015] Thirdly, this application provides a positive electrode material, which includes the aforementioned positive electrode active material, binder, and conductive agent.

[0016] Fourthly, this application provides a battery including a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the positive electrode includes a current collector and a positive electrode material located on the current collector, and the positive electrode material is as described above.

[0017] The method for preparing nitrogen-doped vanadium dioxide materials provided in this application involves a one-step hydrothermal reaction of a vanadium source, lysine, and water. In this process, lysine acts as both a reducing agent and a nitrogen source, eliminating the need for separate additions of reducing agents and nitrogen sources, as well as the high-temperature calcination step. This method effectively simplifies the preparation process, reduces production costs, and improves the conductivity and cycle stability of the resulting material. Furthermore, due to the small molecular size of lysine, it can uniformly contact the vanadium source under hydrothermal conditions, facilitating uniform in-situ doping of nitrogen in the vanadium dioxide lattice. This allows for effective control of the material's band structure, enhancing electronic conductivity. In addition, the one-step hydrothermal method reduces the risk of excessive grain growth or structural collapse that may occur during high-temperature calcination, helping to maintain a high specific surface area and stable structure, thus resulting in better cycle stability during charge and discharge. Attached Figure Description

[0018] Figure 1 This is a process flow diagram of the preparation method of nitrogen-doped vanadium dioxide positive electrode active material provided in the embodiments of this application.

[0019] Figure 2 The X-ray diffraction (XRD) pattern of the nitrogen-doped vanadium dioxide material prepared in Example 1 of this application is shown.

[0020] Figure 3 This is a scanning electron microscope (SEM) image of the nitrogen-doped vanadium dioxide material prepared in Example 1 of this application.

[0021] Figure 4 This is a comparison of the ultraviolet-visible absorption spectra (UV-Vis) of the materials prepared in Example 1 and Comparative Example 1 of this application.

[0022] Figure 5 The graph shows the cycling performance of an aqueous calcium-ion half-cell assembled from the nitrogen-doped vanadium dioxide material prepared in Example 1 of this application at a current density of 5 A / g. Detailed Implementation

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this application pertain. The terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the embodiments of this application. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0024] The following describes some embodiments of this application in detail. Unless otherwise specified, the embodiments and features described below can be combined with each other.

[0025] Vanadium oxide cathode materials generally suffer from poor intrinsic conductivity. To improve this conductivity, elemental doping is commonly employed. However, existing doping methods often involve adding the reducing agent and dopant source separately, resulting in a wide variety of raw materials, complex process control, and difficulty in ensuring doping uniformity. Furthermore, current methods for preparing cathode active materials often employ electrospinning combined with high-temperature calcination, leading to long process flows, high energy consumption, and high costs, while the conductivity and cycle stability of the resulting materials still require improvement.

[0026] For this purpose, please see Figure 1 This application provides a method for preparing a nitrogen-doped vanadium dioxide cathode active material, comprising: Step S1: Mix vanadium source, lysine and water, adjust pH and carry out hydrothermal reaction. During the hydrothermal reaction, the amino group in lysine acts as a reducing agent to reduce the vanadium source to vanadium dioxide. At the same time, the nitrogen element in lysine is doped into the vanadium dioxide lattice in situ to obtain the reaction product.

[0027] Step S2 involves washing and drying the reaction product under vacuum at a temperature of 60℃~80℃ to obtain nitrogen-doped vanadium dioxide material. Washing removes unreacted impurities, while vacuum drying helps maintain the purity and lattice structure integrity of the product.

[0028] The principle of the above preparation method is analyzed as follows: First, lysine molecules are rich in reducing amino groups (-NH2), which can reduce vanadium sources (such as V2O5) to VO2 under hydrothermal conditions, realizing the transformation of vanadium valence state. Second, nitrogen in lysine is released during pyrolysis and in-situ doped into the vanadium dioxide lattice interface, thereby regulating the band structure of the material, reducing the band gap, and improving the intrinsic electronic conductivity.

[0029] In summary, the preparation method provided in this application requires no additional reducing agent or nitrogen source, nor does it require subsequent high-temperature calcination. Nitrogen-doped vanadium dioxide materials can be obtained through a single hydrothermal reaction. This method simplifies the process and reduces production energy consumption and costs. In the resulting material, nitrogen doping enhances electronic conductivity, while the one-step hydrothermal method avoids excessive grain growth or structural collapse that may be caused by high-temperature calcination. This helps maintain the material's high specific surface area and stable tunnel structure, thereby enabling the material to exhibit good cycle stability during charge and discharge.

[0030] In some embodiments, the vanadium source includes at least one of vanadium pentoxide and ammonium metavanadate. Using the above chemical composition as the vanadium source provides a wide range of options and allows for a thorough reaction with lysine under hydrothermal conditions, achieving stable nitrogen doping.

[0031] In some embodiments, the molar mass ratio of lysine to vanadium in the vanadium source is 1:2 to 1:4. Controlling this ratio within this range helps ensure sufficient reduction of the vanadium source, provides an appropriate amount of nitrogen source to achieve uniform in-situ doping, and thus obtains nitrogen-doped vanadium dioxide materials with good crystallinity and uniform doping.

[0032] In some embodiments, the hydrothermal reaction temperature is 160°C to 200°C, and the time is 18h to 36h. Conducting the hydrothermal reaction within this temperature range facilitates moderate pyrolysis of lysine, releasing sufficient nitrogen atoms to achieve uniform doping and thus obtaining nitrogen-doped vanadium dioxide materials with good crystallinity. Conducting the hydrothermal reaction within this time range ensures sufficient reduction of the vanadium source and adequate nitrogen doping, contributing to the formation of uniform nanostructures, maintaining lattice integrity and high specific surface area, thereby improving the electronic conductivity and electrochemical stability of the material.

[0033] In some embodiments, the pH value is 2-4. Maintaining the pH value of the reaction system within this range is beneficial for lysine and vanadium ions to form a stable complexing environment, promoting uniform nucleation and growth of vanadium dioxide crystals, and simultaneously improving the in-situ doping efficiency of nitrogen.

[0034] In some embodiments, the mixing stirring frequency is 1200 rpm to 2000 rpm, and the time is 120 min to 180 min. Controlling the stirring frequency and time within the above range can ensure that the vanadium source and lysine are fully and uniformly dispersed in water, providing a uniform reaction environment for the uniform reduction of the vanadium source and the uniform doping of nitrogen in the subsequent hydrothermal reaction, which is beneficial to improving the structural consistency and electrochemical performance stability of the product.

[0035] Compared with the prior art, the method for preparing nitrogen-doped vanadium dioxide materials provided in this application has the following beneficial effects: 1. By mixing lysine with a vanadium source and carrying out a one-step hydrothermal reaction, lysine simultaneously acts as a reducing agent and nitrogen source, achieving both vanadium source reduction and in-situ nitrogen doping without the need for additional reducing agents or nitrogen-containing polymers, or subsequent high-temperature calcination. Firstly, the number of raw materials is reduced, requiring only a vanadium source and lysine (and water), lowering raw material procurement and inventory costs. Secondly, the process is shortened, comprising only three steps: precursor preparation, hydrothermal reaction, and post-processing, eliminating the need for intermediate product separation or multiple heat treatments, thus improving production efficiency. Thirdly, the hydrothermal reaction temperature is below 200°C, and subsequent high-temperature (typically >500°C) calcination is unnecessary, reducing energy consumption and equipment requirements. Finally, the entire synthesis process is carried out under mild conditions, without involving toxic or hazardous reagents, producing few byproducts, making it environmentally friendly and easily scalable for large-scale production. In summary, the preparation method provided in this application is characterized by its simple process, low cost, and environmental friendliness, possessing promising prospects for industrial application.

[0036] 2. The lysine molecules used in the preparation method of this application are small in size and can be uniformly dispersed and fully contacted with the vanadium source under hydrothermal conditions. This is beneficial for the uniform in-situ doping of nitrogen in the vanadium dioxide lattice, thereby regulating the band structure of the material and improving the intrinsic electronic conductivity of the material.

[0037] 3. This application avoids excessive grain growth or structural collapse that may be caused by high-temperature calcination through a one-step hydrothermal method, which helps to maintain the material's high specific surface area and stable tunnel structure, and makes the material exhibit better cycle stability during charge and discharge.

[0038] This application also provides a positive electrode active material prepared by the aforementioned method. The positive electrode active material prepared by this method has a uniform nitrogen doping distribution and good lattice integrity. When used as a positive electrode active material in aqueous calcium-ion batteries, it can provide stable capacity output and a long cycle life. It is understood that the nitrogen-doped vanadium dioxide positive electrode active material prepared by the aforementioned method can also be used for other applications, such as positive electrode materials for other aqueous multivalent metal-ion batteries (e.g., zinc-ion batteries, magnesium-ion batteries). Those skilled in the art can apply this material to different electrochemical energy storage or functional device fields according to actual needs, all of which are within the scope of protection of this application.

[0039] This application also provides a cathode material, which includes the aforementioned cathode active material, binder, and conductive agent. The cathode material composed of this cathode active material, binder, and conductive agent can form a good electron transport network and ion diffusion channels, which is beneficial for fully utilizing the electrochemical performance of the active material.

[0040] This application also provides a battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode includes a current collector and a positive electrode material layer coated on the current collector, the positive electrode material layer comprising the aforementioned positive electrode material. This battery, using the aforementioned positive electrode material layer, combined with a suitable negative electrode, separator, and electrolyte, can achieve a stable charge-discharge process, exhibiting good rate performance and cycle life.

[0041] The present application will be further described below with reference to specific embodiments and comparative examples.

[0042] Example 1 This embodiment provides a method for preparing nitrogen-doped vanadium dioxide (N-VO2) materials, using lysine as the nitrogen source and reducing agent, and achieving nitrogen doping and vanadium oxide reduction through a hydrothermal reaction. The specific steps are as follows: Step 1: Preparation of precursor solution: 0.712g (99.5% purity) of vanadium pentoxide (V₂O₅) and 0.146g of lysine (C₆H₂O) were added. 14N₂O₂ (molecular weight 146.19, equivalent to 1 mmol) and 4 mL of glacial acetic acid (CH₃COOH) were sequentially added to 60 mL of deionized water. The pH was adjusted to between 2 and 3, and the mixture was magnetically stirred at 1200 rpm for 120 minutes to form a homogeneous dispersion. Lysine acts as a reducing agent and structure-directing agent, promoting the reduction of V₂O₅ and the formation of nanoribbon morphology in the subsequent hydrothermal reaction. Glacial acetic acid in this step provides an acidic environment to aid in the dissociation of V₂O₅.

[0043] Step 2: Hydrothermal Reaction: The above mixed dispersion was transferred to a sealed 100mL stainless steel high-pressure reactor lined with polytetrafluoroethylene, and then placed in an explosion-proof oven. The temperature was raised to 180°C and maintained for 24 hours for hydrothermal reaction. At this temperature, lysine undergoes pyrolysis, releasing nitrogen atoms that are in situ doped into the VO2 lattice, while V2O5 is reduced to VO2.

[0044] Step 3: Post-processing: After the reaction is complete, the mixture is allowed to cool naturally to room temperature, and the precipitate is collected by centrifugation. The precipitate is washed three times each with deionized water and anhydrous ethanol to remove unreacted lysine and byproducts. Finally, the washed product is dried overnight in a vacuum oven at 70°C to obtain the target product, nitrogen-doped vanadium dioxide (N-VO2) nanoribbons.

[0045] Comparative Example 1: Undoped vanadium dioxide (VO2) material: A method for preparing conventional vanadium dioxide (VO2) material is provided, which differs from Example 1 only in that lysine is not added, but an equal amount of ethylene glycol (1 mmol) is added as a reducing agent. The remaining steps and parameters are exactly the same as in Example 1.

[0046] Material characterization: XRD characterization: The phase composition of the sample obtained in Example 1 was analyzed using an X-ray diffractometer. The test conditions were: CuKα rays (λ=0.15406nm), scanning range 2θ=5~60°, and scanning speed 10° / min. The crystal structure of the sample was determined by comparison with a standard powder diffraction card (PDF#31-1438).

[0047] Scanning electron microscopy (SEM): The morphology of the samples obtained in Example 1 was observed using a field emission scanning electron microscope. A small amount of powder sample was taken and evenly adhered to a sample stage covered with conductive adhesive. Unadhesive sample particles were gently blown away with a bulb syringe, followed by gold sputtering to increase conductivity. Simultaneously, elemental composition analysis of the samples was performed using energy-dispersive X-ray spectroscopy (EDS).

[0048] Ultraviolet-Vis (UV-Vis) spectroscopy testing: The optical absorption properties of the samples obtained in Example 1 and Comparative Example 1 were tested using a UV-Vis spectrophotometer. The test wavelength range was 200 nm to 800 nm. Based on the test results, the band gap was calculated using the Taucplot formula.

[0049] Results analysis: Please refer to [link / reference] Figure 2 In this application, the product prepared in Example 1 was characterized by XRD. The results showed that its characteristic peaks were in high agreement with the PDF#31-1438 card of VO2(B), indicating that the obtained product was a pure-phase VO2(B) tunnel structure. This demonstrates that the diamino group in the lysine molecule played a reducing role during the hydrothermal process, successfully reducing orthorhombic V2O5 to VO2(B). Specifically, glacial acetic acid provided a weakly acidic environment in the solution, promoting the dissociation of V2O5 into VO2. + Ions; subsequently, VO2 + It reacts with the amino group (-NH2) of lysine and is reduced to VO2; under hydrothermal conditions at 180℃, VO2 crystal nuclei gradually form and grow into products with specific morphologies under the guidance of lysine residues.

[0050] In addition, the material obtained in Example 1 was characterized by scanning electron microscopy (SEM), and the results are as follows: Figure 3 As shown, the material exhibits a uniform nanowire morphology, with a width of approximately a few nanometers and a length of approximately two to three micrometers. This high aspect ratio nanowire structure facilitates the exposure of more electrochemically active sites. Energy-dispersive X-ray spectroscopy (EDS) revealed the presence of V, O, and N elements in the material, with the presence of N confirming successful nitrogen doping.

[0051] To evaluate the conductivity of the materials in this application, ultraviolet-visible spectroscopy (UV-Vis) tests were performed on the nitrogen-doped vanadium dioxide material prepared in Example 1 and the undoped vanadium dioxide material prepared in Comparative Example 1. The results are as follows: Figure 4 As shown. Compared with the undoped vanadium dioxide material of Comparative Example 1, the band gap (Eg) of the nitrogen-doped vanadium dioxide material obtained in Example 1 is narrower. The reduction in band gap indicates that the energy required for electrons to transition from the valence band to the conduction band is reduced, demonstrating that the intrinsic electronic conductivity of the material is improved by nitrogen doping vanadium dioxide in Example 1.

[0052] Preparation of working electrode sheet: Graphite paper is used as the current collector for preparation, which includes three steps: pulping, coating and drying.

[0053] Step 1: Slurry preparation: Nitrogen-doped vanadium dioxide (N-VO2) prepared in Example 1 and Comparative Example 1 is used as the active material, SuperP as the conductive agent, and polyvinylidene fluoride (PVDF) as the binder. They are dry-mixed at a mass ratio of 6:3:1. Then, an appropriate amount of N-methylpyrrolidone (NMP) is added as a solvent, and the mixture is stirred continuously until a uniform and moderately fluid slurry is formed.

[0054] Step 2: Coating: Take the above slurry and apply it evenly to the surface of graphite paper using a doctor blade. The doctor blade gap is set to 150 μm to control the wet film thickness. Graphite paper is selected as the current collector due to its excellent electrical conductivity and chemical stability.

[0055] Step 3: Drying and Cutting: Place the coated graphite paper in a 70°C vacuum drying oven and dry for 8 hours to fully remove the NMP solvent. After drying, remove the paper and cut it into small circular pieces with a diameter of 10mm using a cutting machine. The mass of active material on the resulting electrode pieces is 0.8mg~1.5mg (which can be achieved by adjusting the coating area or the slurry concentration), thus obtaining the working electrode.

[0056] Assembly of 2032 button cells: A two-electrode system is used, and the entire assembly process is carried out in an air environment.

[0057] Battery structure: The N-VO2 electrode sheet prepared above is used as the working electrode, and the activated carbon cloth (cut into a circular sheet with a diameter of 12 mm) is used as the counter electrode and also as the reference electrode (in the two-electrode system, the counter electrode also serves as the reference electrode).

[0058] Diaphragm: Whatman GF / D glass fiber filter paper is used as the diaphragm and cut into circular pieces with a diameter of 19mm for later use.

[0059] Electrolyte: A eutectic electrolyte was prepared by mixing hydrated calcium perchlorate (Ca(ClO4)24H2O) and acetamide (CH3CONH2) in a molar ratio of 1:6. The specific preparation method was as follows: a certain amount of hydrated calcium perchlorate and acetamide were mixed, heated and stirred until a homogeneous and transparent liquid was formed, and then cooled for later use. This eutectic electrolyte exhibits a wide electrochemical window and good ionic conductivity.

[0060] Cycle capacity retention test: The coin cells assembled in Example 1 were subjected to constant current charge-discharge tests using the Blue Electric testing system. The tests were conducted in an air environment at room temperature, under the following conditions: current density 5 Ag. -1 The voltage range is -1.2 to 1V (relative to activated carbon), and the cycle count is 9000. Capacity retention is calculated using the following formula: Capacity retention rate (%) = (specific capacity of discharge in the Nth cycle / specific capacity of discharge in the first cycle) × 100%.

[0061] The nitrogen-doped vanadium dioxide material prepared in Example 1 was assembled into an aqueous calcium-ion half-cell (see the battery preparation method described above for specific assembly methods), and its electrochemical performance was tested. The results are as follows: Figure 5 As shown in the figure. Test results show that the initial discharge specific capacity of this material is 134.7 mAh g. -1 After 9000 charge-discharge cycles, the capacity retention was 83.5%. These results demonstrate that the nitrogen-doped vanadium dioxide nanowire material prepared in Example 1 exhibits good cycle stability. Furthermore, this material is also suitable for zinc-ion and magnesium-ion battery systems, showing promising application prospects as a cathode material for multivalent ion batteries.

[0062] In summary, the method for preparing nitrogen-doped vanadium dioxide cathode active material provided in this application simplifies the process and reduces production costs by using lysine as both a reducing agent and a nitrogen source through a one-step hydrothermal reaction. The resulting material exhibits uniform nitrogen doping, good conductivity, and good cycle stability, making it suitable as a cathode material for aqueous multivalent metal ion batteries such as calcium, zinc, and magnesium ions.

[0063] The above description describes some specific embodiments of this application, but in actual applications, the application should not be limited to these embodiments. For those skilled in the art, other modifications and alterations made based on the technical concept of this application should fall within the protection scope of this application.

Claims

1. A method for preparing a nitrogen-doped vanadium dioxide cathode active material, characterized in that, include: A vanadium source, lysine, and water are mixed, and a hydrothermal reaction is carried out after adjusting the pH. During the hydrothermal reaction, the amino group in the lysine acts as a reducing agent to reduce the vanadium source to vanadium dioxide. At the same time, the nitrogen element in the lysine is doped into the vanadium dioxide lattice in situ to obtain the reaction product, which is the nitrogen-doped vanadium dioxide positive electrode active material.

2. The preparation method according to claim 1, characterized in that, The molar mass ratio of lysine to vanadium in the vanadium source is 1:2 to 1:

4.

3. The preparation method according to claim 1, characterized in that, The vanadium source includes at least one of vanadium pentoxide and ammonium metavanadate.

4. The preparation method according to claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 160℃ to 200℃ for a duration of 18h to 36h.

5. The preparation method according to claim 1, characterized in that, The pH value is 2 to 4.

6. The preparation method according to claim 1, characterized in that, The stirring frequency for mixing the vanadium source, lysine, and water is 1200 rpm to 2000 rpm, and the stirring time is 120 min to 180 min.

7. The preparation method according to claim 1, characterized in that, After the hydrothermal reaction step, the method further includes washing and drying the reaction product, wherein the drying is vacuum drying at a temperature of 60°C to 80°C.

8. A positive electrode active material, characterized in that, The positive electrode active material is prepared by the preparation method according to any one of claims 1 to 7.

9. A positive electrode material, characterized in that, The positive electrode material includes the positive electrode active material, binder, and conductive agent as described in claim 8.

10. A battery, characterized in that, It includes a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode includes a current collector and a positive electrode material located on the current collector. The positive electrode material is the positive electrode material as described in claim 9.

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