Titanium-doped high-nickel layered oxide material, and preparation method and application thereof

Abstract

The application discloses a titanium-doped high-nickel layered oxide material and a preparation method and application thereof, and belongs to the technical field of sodium ion batteries. The preparation steps are as follows: a mixed solution containing nickel, iron and manganese is prepared; a precipitant solution is mixed with a complexing agent to obtain a first solution, and an alkali solution is prepared as a mother liquor; under an inert atmosphere, the mixed solution and the first solution are simultaneously added into the mother liquor, and a co-precipitation reaction is carried out at 50-60 DEG C for 15-20 h; after the reaction is completed, a solid precipitate is separated, washed and dried to obtain a transition metal hydroxide precursor, Ni x Mn y Fe y (OH)2, x+y+z=1, 0.4 z The transition metal hydroxide precursor is mixed with a sodium source and a titanium source, and then wet ball milling is carried out, and the mixture is dried to obtain a mixed powder; the mixed powder is gradient calcined to obtain the titanium-doped high-nickel layered oxide material. The application can improve the structural stability of the material and has good electrochemical performance.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery technology, specifically to a titanium-doped high-nickel layered oxide material, its preparation method, and its application. Background Technology

[0002] With the widespread application of lithium-ion batteries in electric vehicles and large-scale energy storage, the scarcity of lithium resources, uneven geographical distribution, and rising costs are becoming increasingly prominent issues. Sodium-ion batteries, due to their similar working principle to lithium-ion batteries and the abundance and wide distribution of sodium, are considered one of the most promising alternative technologies. Among the various components of sodium-ion batteries, the cathode material is crucial in determining its energy density, cycle life, and cost. Among numerous cathode materials, layered transition metal oxides (Na₂O₃) are particularly important. x TMO2 (where TM is a transition metal) is considered one of the most promising cathode material systems for realizing high-energy-density sodium-ion batteries due to its high reversible capacity and high operating voltage.

[0003] Compared to high-nickel cathode materials for lithium-ion batteries, sodium-ion cathode materials have the disadvantage of a larger ionic radius. A larger ionic radius requires a larger interlayer spacing during the synthesis of layered materials, which makes the crystal more susceptible to stress during nucleation and growth, leading to dislocations or impurity phase formation. Furthermore, sodium ions are more chemically reactive, with a lower volatilization temperature and more severe volatilization. This significantly affects the accuracy of the initial sodium content, resulting in changes in the initial phase of the material (a higher initial sodium content leads to the formation of the O3 phase, while a lower initial sodium content leads to the formation of the P2 phase). Additionally, depending on the stacking method of the Na layer and the transition metal layer, the Na... x TMO2 is mainly divided into O3 phase structure and P2 phase structure. Among them, the P2 phase oxide has a wide Na content. + Transmission channel, Na + This channel allows direct diffusion between two adjacent triangular prism sites, resulting in good rate capability. O3 phase oxides, on the other hand, possess a high Na content. + The content of these two Na+ compounds can provide high specific capacity. However, these two Na+ compounds... x Both TMO2 and TMO2 have the drawback of undergoing phase structure changes under high voltage, which can lead to huge volume changes and structural degradation in the material.

[0004] In view of the problems existing in the prior art, the present invention, combining years of design and use experience in related fields, designs a titanium-doped high-nickel layered oxide material and its preparation method and application to overcome the above defects. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a titanium-doped high-nickel layered oxide material, its preparation method, and its application. By co-precipitation, ball milling, and gradient calcination working synergistically, and by controlling the ratio of each raw material, trace amounts of metal ions—titanium and nickel—are introduced to achieve a synergistic effect. This fundamentally stabilizes the crystal structure from within the material, suppresses harmful phase transitions, and expands the interlayer spacing to a certain extent, thereby better adapting to the larger ionic radius of sodium and improving the material's air stability.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for preparing a titanium-doped high-nickel layered oxide material, comprising the following steps: Step 1: Prepare a mixed solution of water-soluble Ni salt, Fe salt, and Mn salt according to the required ratio of Ni, Fe, and Mn, wherein the total concentration of metal ions in the mixed solution is 1-2 mol / L; Step 2: Mix the precipitant solution and complexing agent evenly to form the first solution, and prepare an alkaline solution with pH=12 as the mother liquor; Step 3: Under an inert atmosphere, the mixed solution and the first solution are simultaneously added to the mother liquor, and a co-precipitation reaction is carried out at 50-60℃ for 15-20 hours. After the reaction is completed, the solid precipitate is filtered, washed, and dried to obtain the transition metal hydroxide precursor, Ni. x Mn y Fe z (OH)2, x+y+z=1, 0.4<x≤0.8, 0.1≤y≤0.4, 0.1≤z≤0.25; Step 4: Mix the transition metal hydroxide precursor with sodium source and titanium source in the required ratio, then wet ball mill and dry to obtain mixed powder; Step 5: The mixed powder is calcined in an oxygen atmosphere to obtain the titanium-doped high-nickel layered oxide material.

[0007] Preferably, the ratio of total metal ions, precipitant solution, and complexing agent in the mixed solution is 1:(2.5-3):(0.25-0.3) based on molar concentration.

[0008] Preferably, the complexing agent is ammonia water with a mass fraction of 25-28%.

[0009] Preferably, the precipitant solution is a sodium hydroxide solution or a potassium hydroxide solution with a pH of 12.

[0010] Preferably, in step 4, the sodium source is sodium carbonate or sodium nitrate, and the titanium source is titanium dioxide.

[0011] Preferably, in step 5, the gradient calcination step includes a pre-calcination stage, a high-temperature sintering stage, and a cooling stage, wherein: Preheating stage: Increase the temperature to 500℃-600℃ at a rate of 2-4℃ / min and hold for 5-6 hours; High-temperature sintering stage: Increase the temperature to 800℃-920℃ at a rate of 3-5℃ / min and hold for 15-20 hours. Cooling stage: After high-temperature sintering, the temperature is reduced to 110-120℃ at a rate of 1-2℃ / min, and the material is quickly transferred to an argon-filled glove box for sealing and storage, thus obtaining the titanium-doped high-nickel layered oxide material.

[0012] Preferably, the wet ball milling process involves mixing the transition metal hydroxide precursor with sodium and titanium sources in the required ratio and placing the mixture in a ball milling jar. Anhydrous ethanol is then added for ball milling at a speed of 400-600 r / min for 2-8 h.

[0013] Preferably, in step 4, the molar ratio of the transition metal hydroxide precursor to the sodium source and the titanium source is 1.1:(1-x):x, where 0 < x ≤ 0.07.

[0014] A second aspect of the present invention provides a titanium-doped high-nickel layered oxide material prepared by the above-described preparation method.

[0015] A third aspect of the present invention provides the application of the titanium-doped high-nickel layered oxide material in the preparation of sodium-ion batteries.

[0016] The advantages of this invention are: 1. This invention utilizes the synergistic effects of co-precipitation, ball milling, and high-temperature calcination, along with the addition of specific raw materials in each step, to introduce trace amounts of titanium ions. Titanium ions have a good anchoring effect on sodium ions, effectively reducing the structural collapse problem after deep sodium removal, improving the reversibility of the layered structure, and enabling more sodium ions to quickly re-intercalate into the positive electrode, thereby achieving a higher discharge specific capacity. The battery produced in this way has a discharge specific capacity of up to 227.47 mAh / g. Furthermore, in a high-nickel environment (nickel content > 0.4%), titanium ions play a positive role. At this time, charge compensation is mainly provided by the redox reaction of nickel. Manganese and iron mainly play auxiliary roles such as stabilizing the structure, suppressing phase transitions, and optimizing ion transport channels in a high-nickel concentration environment. Attached Figure Description

[0017] Figure 1 The first charge-discharge curve and cycle performance curve of the sodium-ion battery assembled in Example 1 of this invention at a current of 0.1C are shown. Figure 2 The first charge-discharge curve of the sodium-ion battery assembled in Example 2 of this invention at a current of 0.1C is shown. Figure 3This is a graph showing the first charge-discharge curve of the sodium-ion battery assembled in Example 3 of this invention at a current of 0.1C. Figure 4 This is a graph showing the first charge-discharge curve of the sodium-ion battery assembled in Example 4 of this invention at a current of 0.1C. Figure 5 The first charge-discharge curve of the sodium-ion battery assembled in Example 5 of this invention at a current of 0.1C is shown. Figure 6 The first charge-discharge curves of the sodium-ion batteries assembled in Example 6 and Comparative Example 7 of this invention at a current of 0.1C are shown. Figure 7 The graphs show the initial charge-discharge curves of the sodium-ion batteries assembled in Example 7 and Comparative Example 8 of this invention at a current of 0.1C. Figure 8 The first charge-discharge curves of the sodium-ion batteries assembled in Comparative Example 1 and Comparative Example 2 in this invention at a current of 0.1C are shown. Figure 9 The first charge-discharge curves of the sodium-ion batteries assembled in Comparative Examples 3 and 4 of this invention at a current of 0.1C are shown. Figure 10 This is a graph showing the first charge-discharge curve of the sodium-ion battery assembled in Comparative Example 5 of this invention at a current of 0.1C. Figure 11 This is a graph showing the first charge-discharge curve of the sodium-ion battery assembled in Comparative Example 6 of this invention at a current of 0.1C. Figure 12 The first charge-discharge curves of the sodium-ion batteries assembled in Example 3 and Comparative Example 9 of this invention at a current of 0.1C are shown. Detailed Implementation

[0018] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to specific embodiments.

[0019] The first aspect of this invention provides a method for preparing a titanium-doped high-nickel layered oxide material, comprising the following steps: Step 1: Prepare a mixed solution of water-soluble Ni salt, Fe salt, and Mn salt according to the required ratio of Ni, Fe, and Mn, wherein the total concentration of metal ions in the mixed solution is 1-2 mol / L; Step 2: Mix the precipitant solution and complexing agent evenly to form the first solution, and prepare an alkaline solution with pH=12 as the mother liquor; Step 3: Under an inert atmosphere, the mixed solution and the first solution are simultaneously added to the mother liquor, and a co-precipitation reaction is carried out at 50-60℃ for 15-20 hours. The pH of the solution is controlled at 12 during the reaction. After the reaction, the solid precipitate is obtained by filtration, washing, and drying to obtain the transition metal hydroxide precursor, Ni. x Mn y Fe z (OH)2, x+y+z=1, 0.4<x≤0.8, 0.1≤y≤0.4, 0.1≤z≤0.25; Step 4: Mix the transition metal hydroxide precursor with sodium source and titanium source in a molar ratio of 1.1:(1-x):x (0<x≤0.07), place the mixture in a ball mill, add anhydrous ethanol and ball mill at a speed of 400-600 r / min for 2-8 h, and then dry to obtain a mixed powder. Step 5: The mixed powder is calcined in an oxygen atmosphere using a gradient method. First, the temperature is increased to 500℃-600℃ at a rate of 2-4℃ / min and held for 5-6 hours for pre-calcination. Then, the temperature is increased to 800℃-920℃ at a rate of 3-5℃ / min and held for 15-20 hours for high-temperature calcination. Finally, the temperature is reduced to 110-120℃ at a rate of 1-2℃ / min and then quickly transferred to an argon-filled glove box for sealing and storage. The titanium-doped high-nickel layered oxide material is obtained. Loose sintering or pellet sintering can be selected according to the elemental uniformity of the sample.

[0020] This invention successfully prepares titanium-doped high-nickel ternary layered oxides by synergistically combining co-precipitation, wet ball milling, and gradient calcination, while adding specific raw materials and controlling their amounts at each step. Specifically, the traditional co-precipitation method is used as the main method, followed by solid-phase ball milling to introduce Ti. 4+ As a supplement, using Ti 4+ The ability of ions to anchor structures provides structural support for nickel-based oxide materials, while simultaneously balancing the average valence state of transition metal ions, thereby producing stable O3-phase titanium-doped high-nickel layered oxide materials. In nickel-based layered oxide materials, under low-nickel conditions, i.e., Ni... + When the content is ≤0.4%, Ti 4+ If ineffective or with adverse effects, nickel, manganese, and iron work synergistically to provide charge compensation. They participate in redox reactions during sodium ion extraction and insertion, constituting a significant source of battery capacity. The introduction of titanium ions occupies the positions of the original charge compensation elements, affecting the redox reactions and leading to a decrease in the discharge specific capacity of batteries assembled from nickel oxide materials doped with titanium ions. This is especially true in high-nickel environments, i.e., Ni... + Content > 0.4%, Ti 4+The charge compensation is primarily provided by the redox reaction of nickel, while manganese and iron play auxiliary roles in stabilizing the structure, suppressing phase transitions, and optimizing ion transport channels in a high nickel concentration environment. NaNiO2 material itself has a very high theoretical capacity, but severe structural collapse occurs after deep desodium removal, resulting in very low coulombic efficiency and difficulty in fully releasing the discharge capacity. Titanium ions have a good anchoring effect on sodium ions, effectively reducing the structural collapse problem after deep desodium removal, improving the reversibility of the layered structure, and allowing more sodium ions to quickly re-intercalate into the positive electrode, thus achieving a higher discharge capacity. Furthermore, the coin cell assembled from this material exhibits high stability, maintaining structural integrity even at a high voltage of 4.4V. Therefore, the titanium-doped high-nickel layered oxide material prepared by this invention can achieve a higher discharge capacity by increasing the voltage window.

[0021] In this invention, the complexing agent is preferably 25-28% ammonia water, and the precipitant solution is a sodium hydroxide solution or potassium hydroxide solution with pH=12. The sodium source is selected from sodium carbonate or sodium nitrate, and the titanium source is selected from titanium dioxide. In terms of molar concentration, the ratio of total metal ions, precipitant solution, and complexing agent in the mixed solution is 1:(2.5-3):(0.25-0.3).

[0022] A second aspect of the present invention provides a titanium-doped high-nickel layered oxide material prepared by the above-described preparation method.

[0023] The third aspect of this invention provides an application of the titanium-doped high-nickel layered oxide material in the preparation of sodium-ion batteries. Specifically, the prepared high-nickel ternary modified layered oxide cathode material is ground and sieved, then mixed with Super P (conductive carbon black) and PVDF (polyvinylidene fluoride) in a mass ratio of 8:1:1, and NMP (N-methylpyrrolidone) is added and stirred into a slurry. The slurry is coated onto aluminum foil, dried, punched, and pressed to form a sodium-ion battery cathode material electrode sheet with a diameter of 11 mm. Metallic sodium is used as the negative electrode, glass fiber is used as the separator, and NaClO4 is used as the electrolyte. CR2025 button batteries are assembled in an argon-filled glove box.

[0024] Specific embodiments are shown below:

[0025] Example 1 A method for preparing a titanium-doped high-nickel layered oxide material includes the following steps: Step 1: Accurately weigh 9.8571g NiSO4·6H2O, 5.0706g MnSO4·H2O, and 1.4991g Fe2(SO4)3 and dissolve them in 50mL of deionized water to prepare a mixed solution with a total concentration of 1.5mol / L. Step 2: Mix 100 mL of KOH with pH=12 and 2 mL of 25% ammonia solution evenly to form the first solution, and prepare an additional 1000 mL of KOH solution with pH=12 as the mother liquor; Step 3: Under an argon atmosphere, the mixed solution and the first solution were simultaneously and slowly added dropwise to 1 L of mother liquor. The co-precipitation reaction was carried out at 55°C and a stirring speed of 500 r / min for 15 h. The pH value was maintained at approximately 12 throughout the reaction. After the reaction, the solid precipitate was obtained by filtration, washing, and drying to obtain the transition metal hydroxide precursor, Ni. 0.5 Mn 0.4 Fe 0.1 (OH)2; Step 4: Accurately weigh 1g of precursor, 0.9192g of NaNO3 and 0.0044g of TiO2 and place them in a ball mill. Add anhydrous ethanol until the powder is submerged. Ball mill at 500r / min for 420min. After ball milling, dry the powder to obtain a mixed powder. Step 5: Under an oxygen atmosphere, the mixed powder is heated from room temperature to 500℃ at a rate of 3℃ / min and held for 5 hours (pre-sintering stage). Then, it is heated to 850℃ at a rate of 5℃ / min and held for 15 hours (high-temperature sintering stage). Finally, it is rapidly transferred to an argon-filled glove box for sealed storage at a rate of 2℃ / min (cooling stage), thus obtaining the titanium-doped high-nickel layered oxide material Na(Ni) 0.5 Mn 0.4 Fe 0.1 ) 0.95 Ti 0.05 O2, as confirmed by XRD testing, is a pure O3 phase layered oxide.

[0026] This embodiment provides a titanium-doped high-nickel layered oxide material prepared by the above-described method.

[0027] This embodiment provides an application of titanium-doped high-nickel layered oxide material in the preparation of sodium-ion batteries, as detailed below: High-nickel layered oxide was ground through a 200-mesh sieve and then mixed with Super P (conductive carbon black) and PVDF (polyvinylidene fluoride) in a mass ratio of 8:1:1. NMP (N-methylpyrrolidone) was added and stirred into a slurry, which was then coated onto aluminum foil. After drying, stamping, and pressing, a sodium-ion battery positive electrode material was produced. Using metallic sodium as the negative electrode, glass fiber (Whatman GF / D) as the separator, and NaClO4 solution as the electrolyte, CR2025 button batteries were assembled in an argon-filled glove box.

[0028] The electrochemical performance of the button cell prepared in this embodiment was tested. Figure 1The graphs show the first charge-discharge curves (left) and the cycle performance curves (right) of the battery made from the titanium-doped high-nickel layered oxide material obtained in this embodiment at a voltage window of 2V-4.2V and a current of 0.1C. As can be seen from the graphs, the first discharge specific capacity of the material at 0.1C is 150.39mAh / g, the first cycle coulombic efficiency is close to 86.55%, and the discharge specific capacity is still greater than 92.49mAh / g after 150 cycles. The capacity retention rate at 1C cycle is 70%.

[0029] Example 2 Step 1: Accurately weigh 9.8571g NiSO4·6H2O, 3.1691g MnSO4·H2O, and 3.7489g Fe2(SO4)3 and dissolve them in 50mL of deionized water to prepare a mixed solution with a total concentration of 1.5mol / L. Step 2: Mix 100 mL of KOH with pH=12 and 1 mL of 28% ammonia solution evenly to form the first solution, and prepare an additional 1000 mL of KOH with pH=12 as the mother liquor; Step 3: Under an argon atmosphere, the mixed solution and the first solution were simultaneously and slowly added dropwise to 1 L of mother liquor. The co-precipitation reaction was carried out at 50°C and a stirring speed of 500 r / min for 15 h. The pH value was maintained at approximately 12 throughout the reaction. After the reaction, the solid precipitate was obtained by filtration, washing, and drying to obtain the transition metal hydroxide precursor, Ni. 0.5 Mn 0.25 Fe 0.25 (OH)2; Step 4: Accurately weigh 1g of precursor, 0.9154g of NaNO3 and 0.0044g of TiO2 and place them in a ball mill. Add anhydrous ethanol until the powder is submerged. Ball mill at 500r / min for 420min. After ball milling, dry the powder to obtain a mixed powder. Step 5: Under an oxygen atmosphere, the mixed powder is heated from room temperature to 500℃ at a rate of 3℃ / min and held for 5 hours (pre-sintering stage). Then, it is heated to 850℃ at a rate of 5℃ / min and held for 15 hours (high-temperature sintering stage). Finally, it is rapidly transferred to an argon-filled glove box for sealed storage at a rate of 2℃ / min (cooling stage), thus obtaining the high-nickel layered oxide material Na(Ni). 0.5 Mn 0.25 Fe 0.25 ) 0.95 Ti 0.05 O2, as confirmed by XRD testing, is a pure O3 phase layered oxide.

[0030] This embodiment provides a titanium-doped high-nickel layered oxide material prepared by the above-described method, and also provides the application of the above-described titanium-doped high-nickel layered oxide material in the preparation of sodium-ion batteries, as detailed below: High-nickel layered oxide was ground through a 200-mesh sieve and then mixed with Super P (conductive carbon black) and PVDF (polyvinylidene fluoride) in a mass ratio of 8:1:1. NMP (N-methylpyrrolidone) was added and stirred into a slurry, which was then coated onto aluminum foil. After drying, stamping, and pressing, a sodium-ion battery positive electrode material was produced. Using metallic sodium as the negative electrode, glass fiber (Whatman GF / D) as the separator, and NaClO4 solution as the electrolyte, CR2025 button batteries were assembled in an argon-filled glove box.

[0031] Electrochemical performance tests were performed on this embodiment. Figure 2 The first charge-discharge curves (left), (middle), and (right) of the battery made of the high-nickel layered oxide material obtained in this embodiment are shown in the following graphs: first charge-discharge curve (left) under a voltage window of 2V-4.2V and a current of 0.1C, second charge-discharge curve (middle) under a voltage window of 2V-4.3V and a current of 0.1C, and third charge-discharge curve (right) under a voltage window of 2V-4.4V and a current of 0.1C. The first discharge specific capacities are 148.68 mAh / g, 161.19 mAh / g, and 167.49 mAh / g, respectively.

[0032] Example 3 Step 1: Accurately weigh 11.8283g NiSO4·6H2O, 2.5353g MnSO4·H2O, and 2.9991g Fe2(SO4)3 and dissolve them in 50mL of deionized water to prepare a mixed solution with a total concentration of 1.5mol / L. Step 2: Add 2 mL of 28% ammonia water to 100 mL of KOH with pH=12 to form the first solution, and prepare an additional KOH solution with pH=12 as the mother liquor; Step 3: Under an argon atmosphere, the mixed solution and the first solution were simultaneously and slowly added dropwise to 1 L of mother liquor. The co-precipitation reaction was carried out at 50°C and a stirring speed of 500 r / min for 15 h. The pH value was maintained at approximately 12 throughout the reaction. After the reaction, the solid precipitate was obtained by filtration, washing, and drying to obtain the transition metal hydroxide precursor, Ni. 0.6 Mn 0.2 Fe 0.2 (OH)2; Step 4: Accurately weigh 1g of precursor, 0.5734g of Na2CO3 and 0.0044g of TiO2 and place them in a ball mill. Add anhydrous ethanol until the powder is submerged. Ball mill at 500r / min for 420min. After ball milling, dry the mixture to obtain a mixed powder. Step 5: Under an oxygen atmosphere, the mixed powder is heated from room temperature to 500℃ at a rate of 3℃ / min and held for 5 hours (pre-sintering stage). Then, it is heated to 850℃ at a rate of 5℃ / min and held for 15 hours (high-temperature sintering stage). Finally, it is rapidly transferred to an argon-filled glove box for sealed storage at a rate of 2℃ / min (cooling stage), thus obtaining the titanium-doped high-nickel layered oxide material Na(Ni) 0.6 Mn 0.2 Fe 0.2 ) 0.95 Ti 0.05 O2, as confirmed by XRD testing, is a pure O3 phase layered oxide.

[0033] This embodiment provides a titanium-doped high-nickel layered oxide material prepared by the above-described method, and also provides an application of the titanium-doped high-nickel layered oxide material in the preparation of sodium-ion batteries, as detailed below: Titanium-doped high-nickel layered oxide was ground through a 200-mesh sieve and then mixed with Super P (conductive carbon black) and PVDF (polyvinylidene fluoride) in a mass ratio of 8:1:1. NMP (N-methylpyrrolidone) was added and stirred to form a slurry, which was then coated onto aluminum foil. After drying, stamping, and pressing, it was used to produce the positive electrode material for sodium-ion batteries. Using metallic sodium as the negative electrode, glass fiber (Whatman GF / D) as the separator, and NaClO4 solution as the electrolyte, CR2025 button batteries were assembled in an argon-filled glove box.

[0034] Electrochemical performance tests were performed on this embodiment. Figure 3 The image shows the first charge-discharge curve of the battery made of titanium-doped high-nickel layered oxide material obtained in this embodiment under a voltage window of 2V-4.2V and a current of 0.1C. The discharge specific capacity is 193.38mAh / g.

[0035] Example 4 Step 1: Accurately weigh 11.8283g NiSO4·6H2O, 2.5353g MnSO4·H2O, and 2.9991g Fe2(SO4)3 and dissolve them in 75mL of deionized water to prepare a mixed solution with a total concentration of 1mol / L. Step 2: Add 2 mL of 28% ammonia to 100 mL of KOH with pH=12 to form the first solution, and prepare an additional KOH solution with pH=12 as the mother liquor; Step 3: Under an argon atmosphere, the mixed solution and the first solution were simultaneously and slowly added dropwise to 1 L of mother liquor. The co-precipitation reaction was carried out at 50°C and a stirring speed of 500 r / min for 15 h. The pH value was maintained at approximately 12 throughout the reaction. After the reaction, the solid precipitate was obtained by filtration, washing, and drying to obtain the transition metal hydroxide precursor, Ni. 0.6 Mn 0.2Fe 0.2 (OH)2; Step 4: Accurately weigh 1g of precursor, 0.9154g of NaNO3 and 0.0026g of TiO2 and place them in a ball mill. Add anhydrous ethanol until the powder is submerged. Ball mill at 500r / min for 420min. After ball milling, dry the mixture to obtain a mixed powder. Step 5: Under an oxygen atmosphere, the mixed powder is heated from room temperature to 550℃ at a rate of 2℃ / min and held for 5.5 hours (pre-sintering stage), then heated to 850℃ at a rate of 3℃ / min and held for 16 hours (high-temperature sintering stage), and finally cooled to 115℃ at a rate of 1℃ / min and rapidly transferred to an argon-filled glove box for sealed storage (cooling stage), thus obtaining the titanium-doped high-nickel layered oxide material Na(Ni) 0.6 Mn 0.2 Fe 0.2 ) 0.97 Ti 0.03 O2, as confirmed by XRD testing, is a pure O3 phase layered oxide.

[0036] This embodiment provides a titanium-doped high-nickel layered oxide material prepared by the above-described method, and also provides an application of the titanium-doped high-nickel layered oxide material in the preparation of sodium-ion batteries, as detailed below: Titanium-doped high-nickel layered oxide was ground through a 200-mesh sieve and then mixed with Super P (conductive carbon black) and PVDF (polyvinylidene fluoride) in a mass ratio of 8:1:1. NMP (N-methylpyrrolidone) was added and stirred to form a slurry, which was then coated onto aluminum foil. After drying, stamping, and pressing, it was used to produce the positive electrode material for sodium-ion batteries. Using metallic sodium as the negative electrode, glass fiber (Whatman GF / D) as the separator, and NaClO4 solution as the electrolyte, CR2025 button batteries were assembled in an argon-filled glove box.

[0037] Electrochemical performance tests were performed on this embodiment. Figure 4 The image shows the first charge-discharge curve of the battery made of titanium-doped high-nickel layered oxide material obtained in this embodiment under a voltage window of 2V-4.2V and a current of 0.1C. The discharge specific capacity is 190.26mAh / g.

[0038] Example 5 Step 1: Accurately weigh 15.7714g NiSO4·6H2O, 3.3804g MnSO4·H2O, and 3.9988g Fe2(SO4)3 and dissolve them in 50mL of deionized water to prepare a mixed solution with a total concentration of 2mol / L. Step 2: Add 2 mL of 28% ammonia water to 100 mL of KOH with pH=12 to form the first solution, and prepare an additional KOH solution with pH=12 as the mother liquor; Step 3: Under an argon atmosphere, the mixed solution and the first solution were simultaneously and slowly added dropwise to 1 L of mother liquor. The co-precipitation reaction was carried out at 50°C and a stirring speed of 500 r / min for 15 h. The pH value was maintained at approximately 12 throughout the reaction. After the reaction, the solid precipitate was obtained by filtration, washing, and drying to obtain the transition metal hydroxide precursor, Ni. 0.6 Mn 0.2 Fe 0.2 (OH)2; Step 4: Accurately weigh 1g of precursor, 0.9154g of NaNO3 and 0.0062g of TiO2 and place them in a ball mill. Add anhydrous ethanol until the powder is submerged. Ball mill at 500r / min for 420min. After ball milling, dry the mixture to obtain a mixed powder. Step 5: Under an oxygen atmosphere, the mixed powder is heated from room temperature to 600℃ at a rate of 4℃ / min and held for 6 hours (pre-sintering stage), then heated to 920℃ at a rate of 4℃ / min and held for 20 hours (high-temperature sintering stage), and finally cooled to 120℃ at a rate of 1℃ / min and rapidly transferred to an argon-filled glove box for sealed storage (cooling stage), thus obtaining the titanium-doped high-nickel layered oxide material Na(Ni) 0.6 Mn 0.2 Fe 0.2 ) 0.93 Ti 0.07 O2, as confirmed by XRD testing, is a pure O3 phase layered oxide.

[0039] This embodiment provides a titanium-doped high-nickel layered oxide material prepared by the above-described method, and also provides an application of the titanium-doped high-nickel layered oxide material in the preparation of sodium-ion batteries, as detailed below: Titanium-doped high-nickel layered oxide was ground through a 200-mesh sieve and then mixed with SP (conductive carbon black) and PVDF (polyvinylidene fluoride) in a mass ratio of 8:1:1. NMP (N-methylpyrrolidone) was added and stirred to form a slurry, which was then coated onto aluminum foil. After drying, stamping, and pressing, it was used to produce the positive electrode material for sodium-ion batteries. Using metallic sodium as the negative electrode, glass fiber (Whatman GF / D) as the separator, and NaClO4 solution as the electrolyte, CR2025 button batteries were assembled in an argon-filled glove box.

[0040] Electrochemical performance tests were performed on this embodiment. Figure 5 The image shows the first charge-discharge curve of the battery made of titanium-doped high-nickel layered oxide material obtained in this embodiment under a voltage window of 2V-4.2V and a current of 0.1C. The discharge specific capacity is 196.70mAh / g.

[0041] Example 6 Step 1: Accurately weigh 13.7996g NiSO4·6H2O, 1.9015g MnSO4·H2O, and 2.2493g Fe2(SO4)3 and dissolve them in 50mL of deionized water to prepare a mixed solution with a total concentration of 1.5mol / L. Step 2: Mix 100 mL of KOH with pH=12 and 1 mL of 25% ammonia solution evenly to form the first solution, and prepare KOH with pH=12 as the mother liquor. Step 3: Under an argon atmosphere, the mixed solution and the first solution were simultaneously and slowly added dropwise to 1 L of mother liquor. The co-precipitation reaction was carried out at 50°C and a stirring speed of 500 r / min for 15 h. The pH value was maintained at approximately 12 throughout the reaction. After the reaction, the solid precipitate was obtained by filtration, washing, and drying to obtain the transition metal hydroxide precursor, Ni. 0.7 Mn 0.15 Fe 0.15 (OH)2; Step 4: Accurately weigh 1g of precursor, 0.9154g of NaNO3 and 0.0044g of TiO2 and place them in a ball mill. Add anhydrous ethanol until the powder is submerged. Ball mill at 500r / min for 420min. After ball milling, dry the powder to obtain a mixed powder. Step 5: Under an oxygen atmosphere, the mixed powder is heated from room temperature to 500℃ at a rate of 3℃ / min and held for 5 hours (pre-sintering stage). Then, it is heated to 850℃ at a rate of 5℃ / min and held for 15 hours (high-temperature sintering stage). Finally, it is rapidly transferred to an argon-filled glove box for sealed storage at a rate of 2℃ / min (cooling stage), thus obtaining the titanium-doped high-nickel layered oxide material Na(Ni) 0.7 Mn 0.15 Fe 0.15 ) 0.95 Ti 0.05 O2, as confirmed by XRD testing, is a pure O3 phase layered oxide.

[0042] This embodiment provides a titanium-doped high-nickel layered oxide material prepared by the above-described method, and also provides an application of the titanium-doped high-nickel layered oxide material in the preparation of sodium-ion batteries, as detailed below: Titanium-doped high-nickel layered oxide was ground through a 200-mesh sieve and then mixed with SP (conductive carbon black) and PVDF (polyvinylidene fluoride) in a mass ratio of 8:1:1. NMP (N-methylpyrrolidone) was added and stirred into a slurry, which was then coated onto aluminum foil. After drying, stamping, and pressing, it was made into a sodium-ion battery positive electrode material. Using metallic sodium as the negative electrode, glass fiber (Whatman GF / D) as the separator, and electrolyte as the solution, CR2025 button batteries were assembled in an argon-filled glove box.

[0043] Electrochemical performance tests were performed on this embodiment. Figure 6 The blue curve represents the first charge-discharge curve of the battery made of titanium-doped high-nickel layered oxide material obtained in this embodiment under a voltage window of 1.5V-4.2V and a current of 0.1C. The first discharge specific capacity is 202.14mAh / g.

[0044] Example 7 Step 1: Accurately weigh 15.7110g NiSO4·6H2O, 1.2676g MnSO4·H2O, and 1.4991g Fe2(SO4)3 and dissolve them in 50mL of deionized water to prepare a mixed solution with a total concentration of 1.5mol / L. Step 2: Mix 100 mL of KOH with pH=12 and 2 mL of 28% ammonia solution evenly to form the first solution, and prepare KOH with pH=12 as the mother liquor. Step 3: Under an argon atmosphere, the mixed solution and the first solution were simultaneously and slowly added dropwise to 1 L of mother liquor. The co-precipitation reaction was carried out at 50°C and a stirring speed of 500 r / min for 15 h. The pH value was maintained at approximately 12 throughout the reaction. After the reaction, the solid precipitate was obtained by filtration, washing, and drying to obtain the transition metal hydroxide precursor, Ni. 0.8 Mn 0.1 Fe 0.1 (OH)2; Step 4: Accurately weigh 1g of precursor, 0.9154g of NaNO3 and 0.0044g of TiO2 and place them in a ball mill. Add anhydrous ethanol until the powder is submerged. Ball mill at 500r / min for 420min. After ball milling, dry the powder to obtain a mixed powder. Step 5: Under an oxygen atmosphere, the mixed powder is heated from room temperature to 500℃ at a rate of 3℃ / min and held for 5 hours (pre-sintering stage). Then, it is heated to 850℃ at a rate of 5℃ / min and held for 15 hours (high-temperature sintering stage). Finally, it is rapidly transferred to an argon-filled glove box for sealed storage at a rate of 2℃ / min (cooling stage), thus obtaining the titanium-doped high-nickel layered oxide material Na(Ni) 0.8 Mn 0.1 Fe 0.1 ) 0.95 Ti 0.05 O2, as confirmed by XRD testing, is a pure O3 phase layered oxide.

[0045] This embodiment provides a titanium-doped high-nickel layered oxide material prepared by the above-described method, and also provides the application of the above-described titanium-doped high-nickel layered oxide material in the preparation of sodium-ion batteries, as detailed below: Titanium-doped high-nickel layered oxide was ground through a 200-mesh sieve and then mixed with Super P (conductive carbon black) and PVDF (polyvinylidene fluoride) in a mass ratio of 8:1:1. NMP (N-methylpyrrolidone) was added and stirred to form a slurry, which was then coated onto aluminum foil. After drying, stamping, and pressing, it was used to produce the positive electrode material for sodium-ion batteries. Using metallic sodium as the negative electrode, glass fiber (Whatman GF / D) as the separator, and electrolyte as the solution, CR2025 button batteries were assembled in an argon-filled glove box.

[0046] Electrochemical performance tests were performed on this embodiment. Figure 7 The blue curve represents the first charge-discharge curve of the battery made of titanium-doped high-nickel layered oxide material obtained in this embodiment under a voltage window of 1.5V-4.2V and a current of 0.1C. The first discharge specific capacity is 227.47mAh / g.

[0047] Comparative Example 1 The material and battery were prepared according to the method of Example 1, the difference being that the raw material ratios in this comparative example are different. Specifically, in step 1, 6.5712g NiSO4·6H2O, 4.2255g MnSO4·H2O, and 4.9985g Fe2(SO4)3 were weighed and dissolved in 50mL of deionized water to prepare a mixed solution with a total concentration of 1.5mol / L, thus obtaining a titanium-doped nickel-containing layered oxide material. 0.3 Mn 0.3 Fe 0.3 ) 0.95 Ti 0.05 O2.

[0048] Electrochemical performance tests were performed on the comparative example. Figure 8 The blue curve in the middle is the first charge-discharge curve of this comparison model under a voltage window of 2V-4.2V and a current of 0.1C. The first discharge specific capacity is 147.15mAh / g.

[0049] Comparative Example 2 Traditional coprecipitation method: Step 1: Accurately weigh 6.5712g NiSO4·6H2O, 4.2255g MnSO4·H2O, and 4.9985g Fe2(SO4)3 and dissolve them in 50mL of deionized water to prepare a mixed solution with a total concentration of 1.5mol / L. Step 2: Mix 100 mL of KOH with pH=12 and 1 mL of 28% ammonia solution evenly to form the first solution, and prepare an additional 1000 mL of KOH with pH=12 as the mother liquor; Step 3: Under an argon atmosphere, the mixed solution and the first solution were simultaneously and slowly added dropwise to 1 L of mother liquor. The co-precipitation reaction was carried out at 50°C and a stirring speed of 500 r / min for 15 h. The pH value was maintained at approximately 12 throughout the reaction. After the reaction, the solid precipitate was obtained by filtration, washing, and drying to obtain the transition metal hydroxide precursor, Ni. 0.3 Mn 0.3 Fe 0.3 (OH)2; Step 4: Accurately weigh 1g of precursor and 0.5734g of Na2CO3 and place them in a mortar and mix thoroughly. Step 5: The mixed powder is heated from room temperature to 500℃ at a rate of 3℃ / min and held for 5 hours in air (pre-sintering stage), then heated to 900℃ at a rate of 5℃ / min and held for 15 hours (high-temperature sintering stage) to obtain the ternary layered oxide material NaNi. 0.3 Mn 0.3 Fe 0.3 O2, as confirmed by XRD testing, is a pure O3 phase layered oxide.

[0050] Electrochemical performance tests were performed on the comparative example. Figure 8 The red curve in the middle is the first charge-discharge curve of this comparative example under a voltage window of 2V-4.2V and a current of 0.1C. The first discharge specific capacity is 149.49mAh / g.

[0051] Comparative Example 3 The material and battery were prepared according to the method of Example 1, the difference being that the raw material ratios in this comparative example are different. Specifically, in step 1, 7.8855g NiSO4·6H2O, 5.0706g MnSO4·H2O, and 2.9991g Fe2(SO4)3 were weighed and dissolved in 50mL of deionized water to prepare a mixed solution with a total concentration of 1.5mol / L, thus obtaining a nickel-containing layered oxide material. 0.4 Mn 0.4 Fe 0.2 ) 0.95 Ti 0.05 O2.

[0052] Electrochemical performance tests were performed on the comparative example. Figure 9 The blue curve in the middle is the first charge-discharge curve of this comparative example under a voltage window of 2V-4.2V and a current of 0.1C. The first discharge specific capacity is 150.73mAh / g.

[0053] Comparative Example 4 Traditional coprecipitation method: Step 1: Accurately weigh 7.8855g NiSO4·6H2O, 5.0706 MnSO4·H2O, and 2.9991g Fe2(SO4)3 and dissolve them in 50mL of deionized water to prepare a mixed solution with a total concentration of 1.5mol / L. Step 2: Mix 100 mL of KOH with pH=12 and 1 mL of 28% ammonia solution to form the first solution. Prepare an additional 1000 mL of KOH with pH=12 as the mother liquor. Step 3: Under an argon atmosphere, the mixed solution and the first solution were simultaneously and slowly added dropwise to 1 L of mother liquor. The co-precipitation reaction was carried out at 50°C and a stirring speed of 500 r / min for 15 h. The pH value was maintained at approximately 12 throughout the reaction. After the reaction, the solid precipitate was obtained by filtration, washing, and drying to obtain the transition metal hydroxide precursor, Ni. 0.4 Mn 0.4 Fe 0.2 (OH)2; Step 4: Accurately weigh 1g of precursor and 0.5734g of Na2CO3 and place them in a mortar and mix thoroughly. Step 5: The mixed powder is heated from room temperature to 500℃ at a rate of 3℃ / min and held for 5 hours in air (pre-sintering stage), then heated to 900℃ at a rate of 5℃ / min and held for 15 hours (high-temperature sintering stage) to obtain the ternary layered oxide material NaNi. 0.4 Mn 0.4 Fe 0.2 O2, as confirmed by XRD testing, is a pure O3 phase layered oxide.

[0054] Electrochemical performance tests were performed on the comparative example. Figure 9 The red curve in the middle is the first charge-discharge curve of this comparative example under a voltage window of 2V-4.2V and a current of 0.1C. The first discharge specific capacity is 146.26mAh / g.

[0055] Comparative Example 5 Traditional coprecipitation method: Step 1: Accurately weigh 9.8571g NiSO4·6H2O, 5.0706g MnSO4·H2O, and 1.4991g Fe2(SO4)3 and dissolve them in 50mL of deionized water to prepare a mixed solution with a total concentration of 1.5mol / L. Step 2: Mix 100 mL of KOH with pH=12 and 1 mL of 28% ammonia solution evenly to form the first solution, and prepare an additional 1000 mL of KOH with pH=12 as the mother liquor; Step 3: Under an argon atmosphere, the mixed solution and the first solution were simultaneously and slowly added dropwise to 1 L of mother liquor. The co-precipitation reaction was carried out at 50°C and a stirring speed of 500 r / min for 15 h. The pH value was maintained at approximately 12 throughout the reaction. After the reaction, the solid precipitate was obtained by filtration, washing, and drying to obtain the transition metal hydroxide precursor, Ni. 0.5 Mn 0.4 Fe 0.1 (OH)2; Step 4: Accurately weigh 1g of precursor and 0.5734g of Na2CO3 and place them in a mortar and mix thoroughly. Step 5: The mixed powder is heated from room temperature to 500℃ at a rate of 3℃ / min and held for 5 hours in air (pre-sintering stage), then heated to 900℃ at a rate of 5℃ / min and held for 15 hours (high-temperature sintering stage) to obtain the ternary layered oxide material NaNi. 0.5 Mn 0.4 Fe 0.1 O2, as confirmed by XRD testing, is a pure O3 phase layered oxide.

[0056] Electrochemical performance tests were performed on the comparative example. Figure 10 The red curve in the middle is the first charge-discharge curve of this comparative example under a voltage window of 2V-4.3V and a current of 0.1C. The first discharge specific capacity is 148.81mAh / g.

[0057] Comparative Example 6 Traditional coprecipitation method: Step 1: Accurately weigh 11.8283g NiSO4·6H2O, 2.5353g MnSO4·H2O, and 2.9991g Fe2(SO4)3 and dissolve them in 50mL of deionized water to prepare a mixed solution with a total concentration of 1.5mol / L. Step 2: Add 2 mL of 28% ammonia water to 100 mL of KOH with pH=12 to form the first solution, and prepare an additional KOH solution with pH=12 as the mother liquor; Step 3: Under an argon atmosphere, the mixed solution and the first solution were simultaneously and slowly added dropwise to 1 L of mother liquor. The co-precipitation reaction was carried out at 50°C and a stirring speed of 500 r / min for 15 h. The pH value was maintained at approximately 12 throughout the reaction. After the reaction, the solid precipitate was obtained by filtration, washing, and drying to obtain the transition metal hydroxide precursor, Ni. 0.6 Mn 0.2 Fe 0.2 (OH)2; Step 4: Accurately weigh 1g of precursor and 0.9154g of NaNO3 and place them in a mortar and mix thoroughly. Step 5: Under an oxygen atmosphere, the mixed powder is heated from room temperature to 500℃ at a rate of 3℃ / min and held for 5 hours (pre-sintering stage). Then, it is heated to 800℃ at a rate of 5℃ / min and held for 15 hours (high-temperature sintering stage). Finally, it is rapidly transferred to an argon-filled glove box for sealed storage at a rate of 2℃ / min (cooling stage) to obtain the high-nickel ternary layered oxide material NaNi. 0.6 Mn 0.2 Fe 0.2 O2, as confirmed by XRD testing, is a pure O3 phase layered oxide.

[0058] Electrochemical performance tests were performed on the comparative example. Figure 11 The red curve in the middle is the first charge-discharge curve of this comparative example under a voltage window of 2V-4.2V and a current of 0.1C. The first discharge specific capacity is 177.28mAh / g.

[0059] Comparative Example 7 Traditional coprecipitation method: Step 1: Accurately weigh 13.7996g NiSO4·6H2O, 1.9015g MnSO4·H2O, and 2.2493g Fe2(SO4)3 and dissolve them in 50mL of deionized water to prepare a mixed solution with a total concentration of 1.5mol / L. Step 2: Add 2 mL of 28% ammonia to 100 mL of KOH with pH=12 to form the first solution, and prepare additional KOH with pH=12 as the mother liquor; Step 3: Under an argon atmosphere, the mixed solution and the first solution were simultaneously and slowly added dropwise to 1 L of mother liquor. The co-precipitation reaction was carried out at 50°C and a stirring speed of 500 r / min for 15 h. The pH value was maintained at approximately 12 throughout the reaction. After the reaction, the solid precipitate was obtained by filtration, washing, and drying to obtain the transition metal hydroxide precursor, Ni. 0.7 Mn 0.15 Fe 0.15 (OH)2; Step 4: Accurately weigh 1g of precursor and 0.9154g of NaNO3 and place them in a mortar and mix thoroughly. Step 5: Under an oxygen atmosphere, the mixed powder is heated from room temperature to 500℃ at a rate of 3℃ / min and held for 5 hours (pre-sintering stage). Then, it is heated to 800℃ at a rate of 5℃ / min and held for 15 hours (high-temperature sintering stage). Finally, it is rapidly transferred to an argon-filled glove box for sealed storage at a rate of 2℃ / min (cooling stage) to obtain the high-nickel ternary layered oxide material NaNi. 0.7 Mn 0.15 Fe 0.15 O2, as confirmed by XRD testing, is a pure O3 phase layered oxide.

[0060] Electrochemical performance tests were performed on the comparative example. Figure 6 The red curve in the middle is the first charge-discharge curve of this comparative example under a voltage window of 1.5V-4.2V and a current of 0.1C. The first discharge specific capacity is 188.50mAh / g.

[0061] Comparative Example 8 Traditional coprecipitation method: Step 1: Accurately weigh 15.7110g NiSO4·6H2O, 1.2676g MnSO4·H2O, and 1.4991g Fe2(SO4)3 and dissolve them in 50mL of deionized water to prepare a mixed solution with a total concentration of 1.5mol / L. Step 2: Add 2 mL of 28% ammonia water to 100 mL of KOH with pH=12 to form the first solution, and prepare an additional KOH solution with pH=12 as the mother liquor; Step 3: Under an argon atmosphere, the mixed solution and the first solution were simultaneously and slowly added dropwise to 1 L of mother liquor. The co-precipitation reaction was carried out at 50°C and a stirring speed of 500 r / min for 15 h. The pH value was maintained at approximately 12 throughout the reaction. After the reaction, the solid precipitate was obtained by filtration, washing, and drying to obtain the transition metal hydroxide precursor, Ni. 0.8 Mn 0.1 Fe 0.1 (OH)2; Step 4: Accurately weigh 1g of precursor and 0.9154g of NaNO3 and place them in a mortar and mix thoroughly. Step 5: Under an oxygen atmosphere, the mixed powder is heated from room temperature to 500℃ at a rate of 3℃ / min and held for 5 hours (pre-sintering stage). Then, it is heated to 800℃ at a rate of 5℃ / min and held for 15 hours (high-temperature sintering stage). Finally, it is rapidly transferred to an argon-filled glove box for sealed storage at a rate of 2℃ / min (cooling stage) to obtain the high-nickel ternary layered oxide material NaNi. 0.8 Mn 0.1 Fe 0.1 O2, as confirmed by XRD testing, is a pure O3 phase layered oxide.

[0062] Electrochemical performance tests were performed on the comparative example. Figure 7 The red curve in the middle is the first charge-discharge curve of this comparative example under a voltage window of 1.5V-4.2V and a current of 0.1C. The first discharge specific capacity is 209.63mAh / g.

[0063] Comparative Example 9 Traditional solid-phase synthesis method: Step 1: Accurately weigh 0.4257g NiO, 0.1652g MnO2, 0.1517g Fe2O3, 0.0399g TiO2 and 0.8924g NaNO3 and place them in a mortar and mix thoroughly. Step 2: Under an oxygen atmosphere, the mixed powder is heated from room temperature to 500℃ at a rate of 3℃ / min and held for 5 hours (pre-sintering stage). Then, it is heated to 850℃ at a rate of 5℃ / min and held for 15 hours (high-temperature sintering stage). Finally, it is rapidly transferred to an argon-filled glove box for sealed storage at a rate of 2℃ / min (cooling stage), thus obtaining the high-nickel ternary layered oxide material Na(Ni) 0.6 Mn 0.2 Fe 0.2 ) 0.95 Ti 0.05 O2, as confirmed by XRD testing, is a pure O3 phase layered oxide.

[0064] Electrochemical performance tests were performed on the comparative example. Figure 12 The red curve in the middle is the first charge-discharge curve of this comparative example under a voltage window of 2V-4.2V and a current of 0.1C. The first discharge specific capacity is 159.19mAh / g.

[0065] Performance Analysis: As can be seen from Examples 1-7, when the titanium-doped high-nickel layered oxide prepared by the present invention is applied to a battery, the discharge specific capacity reaches over 150.39 mAh / g. Figure 2 It can be seen that the battery assembled with titanium-doped high-nickel layered oxide material has a wider selectable voltage window range, and can stably cycle at 2V-4.4V. The higher voltage drives more sodium ions to be inserted and removed from the positive electrode, while activating additional redox reactions. The introduction of titanium ions allows the layered oxide material to maintain its structural integrity under such high voltage. Therefore, the titanium-doped high-nickel layered oxide material prepared in this invention can stably obtain a higher discharge specific capacity by increasing the voltage window.

[0066] Comparing Comparative Example 1 and Comparative Example 2, from... Figure 8 It can be seen that the discharge specific capacity of Comparative Example 1 is slightly lower than that of Comparative Example 2; comparing Comparative Example 3 and Comparative Example 4, from... Figure 9 It can be seen that the discharge specific capacity of Comparative Example 3 is slightly higher than that of Comparative Example 4. This indicates that when the molar content of nickel in the nickel-containing oxide material is ≤0.4%, the addition of titanium to the material results in titanium ions, which do not participate in charge compensation, replacing some of the manganese ions that do participate in charge compensation, thus affecting the battery capacity. Titanium ions have almost no effect on improving the battery capacity of low-nickel layered oxide cathodes or have a negative effect, affecting their energy density. Example 1 and Comparative Example 5 (reference) Figure 1 and Figure 10In comparison, Example 3 and Comparative Example 6 (reference) Figure 3 and Figure 11 In comparison, Example 6 and Comparative Example 7 (reference) Figure 6 Comparison of Example 7 and Comparative Example 8 (see reference) Figure 7 As can be seen from the comparison, when the molar content of nickel in the nickel oxide material is >0.4%, under the preparation method of the present invention, after titanium ions are incorporated into the material, titanium ions can play a positive role, enhance the stability of the layered oxide, maintain the layered structure after deep sodium removal, improve the reversible sodium ion transport efficiency, and make its discharge specific capacity greater than that of the battery assembled from the material without titanium ion doping.

[0067] Comparing Example 3 with Comparative Example 6 (reference) Figure 11 Comparative Example 9 (for reference) Figure 12 The red curves show that, as the traditional solid-state synthesis method produces high-nickel layered oxide materials, the resulting battery has a capacity of only 159.19 mAh / g and low coulombic efficiency. Its electrochemical performance is inferior to that of materials synthesized using the traditional co-precipitation method and the method described in this patent. This indicates that, compared to the co-precipitation process, the traditional solid-state synthesis process results in uneven distribution of transition metal ions, with the presence of enriched regions for certain ions (such as manganese-rich or nickel-rich regions). This uneven distribution not only negatively impacts the insertion and extraction of sodium ions, leading to lower coulombic efficiency, but also weakens the positive influence of titanium ions on the structural rigidity of the layered oxide material. This invention utilizes a synergistic approach combining co-precipitation, solid-state ball milling, and segmented high-temperature calcination to produce high-performance nickel-containing oxide materials.

[0068] Based on the test results of Example 2 (see...) Figure 2 As can be seen, the titanium-doped high-nickel layered oxide material prepared by this invention can be charged at a relatively high voltage of 4.4V, allowing the battery to store more energy. It also exhibits strong adaptability, better meeting the charging and discharging requirements under different temperature conditions and reducing performance fluctuations caused by voltage limitations. The materials prepared in Examples 6 and 7 can stably discharge to a low voltage of 1.5V, releasing more remaining capacity while maintaining a healthy layered structure.

[0069] It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the invention. Furthermore, it should be understood that after reading the technical description of this invention, those skilled in the art can make various alterations, modifications, and / or variations to the invention, and all such equivalent forms also fall within the scope of protection defined by the appended claims.

Claims

1. A method for preparing a titanium-doped high-nickel layered oxide material, characterized in that, Includes the following steps: Step 1: Prepare a mixed solution of water-soluble Ni salt, Fe salt, and Mn salt according to the required ratio of Ni, Fe, and Mn, wherein the total concentration of metal ions in the mixed solution is 1-2 mol / L; Step 2: Mix the precipitant solution and complexing agent evenly to form the first solution, and prepare an alkaline solution with pH=12 as the mother liquor; Step 3: Under an inert atmosphere, the mixed solution and the first solution are simultaneously added to the mother liquor, and a co-precipitation reaction is carried out at 50-60℃ for 15-20 hours. After the reaction is completed, the solid precipitate is filtered, washed, and dried to obtain the transition metal hydroxide precursor, Ni. x Mn y Fe z (OH)2, x+y+z=1, 0.4<x≤0.8, 0.1≤y≤0.4, 0.1≤z≤0.25; Step 4: Mix the transition metal hydroxide precursor with sodium source and titanium source in the required ratio, then wet ball mill and dry to obtain mixed powder; Step 5: The mixed powder is calcined in an oxygen atmosphere to obtain the titanium-doped high-nickel layered oxide material.

2. The method for preparing a titanium-doped high-nickel layered oxide material according to claim 1, characterized in that, The ratio of total metal ions, precipitant solution, and complexing agent in the mixed solution is 1:(2.5-3):(0.25-0.3) based on molar concentration.

3. The method for preparing a titanium-doped high-nickel layered oxide material according to claim 1, characterized in that, The complexing agent is ammonia water with a mass fraction of 25-28%.

4. The method for preparing a titanium-doped high-nickel layered oxide material according to claim 1, characterized in that, The precipitant solution is a sodium hydroxide solution or a potassium hydroxide solution with a pH of 12.

5. The preparation method of the titanium-doped high-nickel layered oxide material according to claim 1, characterized in that, In step 4, the sodium source is sodium carbonate or sodium nitrate, and the titanium source is titanium dioxide.

6. The preparation method of the titanium-doped high-nickel layered oxide material according to claim 1, characterized in that, In step 5, the gradient calcination step includes a pre-calcination stage, a high-temperature sintering stage, and a cooling stage, wherein: Preheating stage: Increase the temperature to 500℃-600℃ at a rate of 2-4℃ / min and hold for 5-6 hours; High-temperature sintering stage: Increase the temperature to 800℃-920℃ at a rate of 3-5℃ / min and hold for 15-20 hours. Cooling stage: After high-temperature sintering, the temperature is reduced to 110℃-120℃ at a rate of 1-2℃ / min, and the material is quickly transferred to an argon-filled glove box for sealing and storage, thus obtaining the titanium-doped high-nickel layered oxide material.

7. The method for preparing a titanium-doped high-nickel layered oxide material according to claim 1, characterized in that, The specific steps of the wet ball milling are as follows: the transition metal hydroxide precursor is mixed with sodium source and titanium source in the required ratio and placed in a ball milling jar. Anhydrous ethanol is added for ball milling. The ball milling speed is 400-600 r / min and the ball milling time is 2-8 h.

8. The method for preparing a titanium-doped high-nickel layered oxide material according to claim 1, characterized in that, In step 4, the molar ratio of the transition metal hydroxide precursor to the sodium source and the titanium source is 1.1:(1-x):x, where 0<x≤0.

07.

9. A titanium-doped high-nickel layered oxide material, characterized in that, It is prepared by the preparation method described in any one of claims 1-8.

10. The application of the titanium-doped high-nickel layered oxide material as described in claim 9 in the preparation of sodium-ion batteries.

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