High-entropy lithium-rich manganese-based precursor, preparation method and application thereof

Abstract

This invention discloses a high-entropy lithium-rich manganese-based precursor, its preparation method, and its application. The preparation method includes the following steps: 1) preparing an aluminum-niobium co-doped nickel-manganese precursor using a co-precipitation method; 2) introducing a doping coating solution, comprising zirconium, tungsten, and titanium, into the reaction system for preparing the aluminum-niobium co-doped nickel-manganese precursor, and continuing the co-precipitation reaction to coat the aluminum-niobium co-doped nickel-manganese precursor, obtaining a doped precursor; 3) sintering the doped precursor to diffuse the dopant elements in the doped precursor, obtaining the high-entropy lithium-rich manganese-based precursor. This invention, through a combination of wet doping and coating in the synthesis stage of the high-entropy lithium-rich manganese-based precursor, achieves uniform element distribution without affecting the morphology and structure of the precursor, effectively improving the structural stability and electrochemical performance of the high-entropy lithium-rich manganese-based cathode material prepared using this precursor.

Description

Technical Field

[0001] This invention belongs to the field of battery technology and relates to a high-entropy lithium-rich manganese-based precursor, its preparation method, and its application. Background Technology

[0002] Lithium-rich manganese-based materials are representative of next-generation low-cost, high-energy-density lithium-ion battery cathode materials. However, although lithium-rich manganese-based materials have significant advantages in specific capacity and great potential, they still suffer from problems such as low initial discharge efficiency, poor rate performance, and voltage decay due to slow technological progress. Mass production and commercialization will take time.

[0003] To address these issues, solutions mainly include coating, acid treatment, doping, pre-cycling, and heat treatment. For example, CN110890541A discloses a method for preparing a surface-modified lithium-rich manganese-based cathode material, comprising the following steps: 1) mixing the raw material of the lithium-rich manganese-based cathode with a fast-ion conductor coating solution, followed by solid-liquid separation to obtain a surface-modified lithium-rich manganese-based cathode material precursor; the solute in the fast-ion conductor coating solution is selected from one or more of soluble hydrogen phosphate, pyrophosphate, and aluminate, and the solvent is water; 2) subjecting the obtained surface-modified lithium-rich manganese-based cathode material precursor to heat treatment to obtain the surface-modified lithium-rich manganese-based cathode material. This patent employs a one-step process, achieving the dual effects of coating and water washing to reduce total alkali content. The process is simple, the conditions are mild, and it is easy to scale up and industrialize. The total alkali content on the surface of the modified material is significantly reduced, and the initial coulombic efficiency and rate performance are greatly improved.

[0004] The method of constructing stable lithium-rich manganese-based cathode materials through entropy stabilization strategies can significantly promote the development of lithium-rich manganese-based materials. Two process routes exist for high-entropy lithium-rich manganese-based cathodes. One is wet doping in the precursor stage. For example, CN106910887B discloses a lithium-rich manganese-based cathode material with the chemical formula Li1+xMnyMzAwOr, where M is at least one of Ni, Co, Al, Mg, Ti, Fe, Cu, Cr, Mo, Zr, Ru, and Sn, and A is at least one of S, P, B, and F, with 0 < x ≤ 1, 0 < y ≤ 1, 0 ≤ z < 1, 0 ≤ w ≤ 0.2, and 1.8 ≤ r ≤ 3. This lithium-rich manganese-based cathode material is prepared by oxalate co-precipitation-spray drying-high-temperature calcination. The method includes at least the following steps: 1) Weighing the corresponding raw materials according to the molar ratio of the chemical formula, mixing and co-precipitating the solutions containing manganese source and M source with the solution containing oxalate ions, and controlling the mixing conditions to obtain a precursor slurry, wherein the solution containing oxalate ions is an ammonium oxalate solution; 2) Spray drying the obtained precursor slurry to obtain precursor powder, and subjecting the obtained precursor powder to low-temperature heat treatment, wherein the conditions for low-temperature heat treatment are: holding at 100-300℃ for 1-20h, and then raising the temperature to 300-500℃ and holding for 1-20h; 3) Mixing the obtained precursor powder, lithium source and A source, and calcining the mixture at high temperature to obtain lithium-rich manganese-based cathode material. However, due to the different precipitation rates of different elements, and even the fact that some elements are easily hydrolyzed, the high-entropy lithium-rich manganese-based precursor has too many doped elements, making the co-precipitation of multiple elements extremely difficult, which also affects the morphology and structure of the precursor and has a negative impact on the material performance. Another approach is to use high temperature during the cathode sintering stage to diffuse elements for doping. However, since the mixing stage relies solely on mechanical mixing, the dopant elements are not evenly distributed on the precursor surface, and the dopant elements are also unevenly distributed during the later high-temperature diffusion.

[0005] Therefore, providing a high-performance, high-entropy lithium-rich manganese-based precursor and its preparation method is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, the present invention aims to provide a high-entropy lithium-rich manganese-based precursor, its preparation method, and its application.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a high-entropy lithium-rich manganese-based precursor, the method comprising the following steps: (1) Aluminum-niobium co-doped nickel-manganese precursor was prepared by co-precipitation; (2) A doping coating solution is introduced into the reaction system for preparing the aluminum-niobium co-doped nickel-manganese precursor. The doping coating solution includes zirconium, tungsten and titanium. The co-precipitation reaction is continued to coat the aluminum-niobium co-doped nickel-manganese precursor to obtain the doped precursor. (3) The doped precursor is sintered to allow the dopant elements in the doped precursor to diffuse, thereby obtaining the high-entropy lithium-rich manganese-based precursor.

[0008] This invention combines wet doping and coating during the synthesis of high-entropy lithium-rich manganese-based precursors. This avoids element segregation and does not affect the morphology and structure of the precursor, effectively improving the structural stability and electrochemical performance of the high-entropy lithium-rich manganese-based cathode material prepared using this precursor. Specifically, easily doped Al and Nb elements are directly wet-doped using co-precipitation, while easily hydrolyzed Ti and Zr elements, and difficult-to-dopant W elements, are uniformly wet-coated. Later, sintering diffuses the coated elements into the precursor, achieving gradient doping. This effectively improves the material's stability, thereby reducing voltage decay and enhancing cycle performance.

[0009] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0010] Preferably, step (1) includes: adding a mixed solution A containing nickel, manganese, aluminum and niobium, a precipitant solution and a complexing agent solution in parallel into a reaction vessel to carry out a co-precipitation reaction to obtain an aluminum-niobium co-doped nickel-manganese precursor.

[0011] Preferably, the total metal concentration in the mixed solution A is 1 mol / L to 3 mol / L, for example, it can be 1 mol / L, 1.2 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.3 mol / L, 2.6 mol / L, 2.8 mol / L or 3 mol / L, etc.

[0012] Preferably, the precipitant solution is liquid alkali, and the concentration of the liquid alkali is 8 mol / L-12 mol / L, for example, it can be 8 mol / L, 8.2 mol / L, 8.5 mol / L, 9 mol / L, 9.5 mol / L, 10 mol / L, 10.5 mol / L, 11 mol / L, 11.5 mol / L or 12 mol / L, etc.

[0013] Preferably, the complexing agent solution is ammonia water, and the concentration of the ammonia water is 5 mol / L-8 mol / L, for example, it can be 5 mol / L, 5.5 mol / L, 6 mol / L, 6.5 mol / L, 7 mol / L, 7.5 mol / L, or 8 mol / L, etc. Using an extremely low concentration of complexing agent in the synthesis of niobium-aluminum doped precursors results in a loose and porous structure, which is beneficial for lithium-ion diffusion and improves the rate performance of the material.

[0014] Preferably, the pH of the coprecipitation reaction in step (1) is 9.0-9.5, for example, it can be 9.0, 9.1, 9.2, 9.3, 9.4 or 9.5.

[0015] Preferably, during the coprecipitation reaction in step (1), the ammonia concentration in the reaction system is 1 g / L - 2 g / L, for example, it can be 1 g / L, 1.2 g / L, 1.3 g / L, 1.4 g / L, 1.5 g / L, 1.7 g / L, 1.8 g / L or 2 g / L, etc.

[0016] Preferably, the temperature of the coprecipitation reaction in step (1) is 40℃-50℃, for example, it can be 40℃, 42℃, 44℃, 45℃, 47℃, 48℃ or 50℃.

[0017] Preferably, the coprecipitation reaction in step (1) is accompanied by stirring, and the stirring speed is 300rpm-500rpm, for example, 300rpm, 320rpm, 330rpm, 340rpm, 360rpm, 380rpm, 400rpm, 420rpm, 440rpm, 460rpm, 480rpm or 500rpm.

[0018] Preferably, the D50 of the aluminum-niobium co-doped nickel-manganese precursor in step (1) is 3µm-18µm, for example, it can be 3µm, 5µm, 7µm, 8µm, 10µm, 12µm, 13µm, 15µm, 16µm or 18µm, etc.

[0019] As a preferred technical solution for the preparation method of the high-entropy lithium-rich manganese-based precursor of the present invention, the doping coating solution in step (2) includes a zirconium-titanium mixed solution B and a sodium tungstate solution C, wherein the zirconium-titanium mixed solution B and the sodium tungstate solution C are introduced into the reaction system in a parallel flow manner.

[0020] Preferably, the pH of the zirconium-titanium mixed solution B is adjusted to 0.5-1 before use, for example, it can be 0.5, 0.6, 0.7, 0.8, 0.9, or 1. Adjusting the pH can, on the one hand, inhibit the hydrolysis of zirconium and titanium ions to form precipitation, creating a stable solution and preventing the formation of new crystal nuclei due to solid impurities in the solution entering the reaction system, thereby stabilizing the reaction conditions of the precursor and making the precursor grain growth more stable and uniform; on the other hand, it avoids the preferential precipitation of zirconium and titanium ions in the raw materials, which would reduce the doping amount in the material. The reagent used to adjust the pH can be dilute sulfuric acid.

[0021] This invention utilizes the fact that titanium ions and zirconium ions hydrolyze to form precipitates under slightly higher pH conditions, and that sodium tungstate solution is alkaline and tungsten precipitates under acidic conditions. No precipitating agent or complexing agent is needed in the coating stage; the two solutions are directly mixed to form a precipitate that coats the surface of the aluminum-niobium co-doped nickel-manganese precursor.

[0022] Preferably, the total metal concentration in the zirconium-titanium mixed solution B is 0.003 mol / L to 0.01 mol / L, for example, it can be 0.003 mol / L, 0.004 mol / L, 0.006 mol / L, 0.008 mol / L or 0.01 mol / L, etc.

[0023] Preferably, the concentration of the sodium tungstate solution C is 0.003 mol / L-0.01 mol / L, for example, it can be 0.003 mol / L, 0.004 mol / L, 0.006 mol / L, 0.008 mol / L, or 0.01 mol / L. Preferably, the temperature of the coprecipitation reaction in step (2) is 40℃-50℃, for example, it can be 40℃, 42℃, 43℃, 45℃, 47℃, or 50℃.

[0024] Preferably, the coprecipitation reaction time in step (2) is 10h-20h, for example, it can be 10h, 12h, 13h, 14h, 15h, 16h, 18h or 20h.

[0025] Preferably, the sintering atmosphere in step (3) is an oxygen-containing atmosphere.

[0026] Preferably, the sintering temperature in step (3) is 500℃-600℃, for example, it can be 500℃, 520℃, 540℃, 550℃, 565℃, 570℃, 580℃, 590℃ or 600℃, etc.

[0027] Preferably, the sintering time in step (3) is 4h-6h, for example, it can be 4h, 4.2h, 4.5h, 4.7h, 5h, 5.5h or 6h.

[0028] Secondly, the present invention provides a high-entropy lithium-rich manganese-based precursor, which is prepared by the method described in the first aspect, and the high-entropy lithium-rich manganese-based precursor has pores on both its surface and interior.

[0029] Preferably, the chemical formula of the high-entropy lithium-rich manganese-based precursor is Ni. x Mn y Al a Zr b W c Ti d Nb e (OH)2, where 0.3≤x≤0.4, 0.6≤y≤0.7, 0.001≤a≤0.01, 0.001≤b≤0.003, 0.001≤c≤0.003, 0.001≤d≤0.003, 0.003≤e≤0.01, and x+y+a+b+c+d+e=1. For example, x can be 0.3, 0.32, 0.35, 0.36, 0.38, or 0.4, etc.; y can be 0.6, 0.62, 0.63, 0.66, 0.68, or 0.7, etc.; a can be 0.001, 0.003, 0.005, 0.007, 0.008, or 0.01, etc.; b can be 0.001, 0.002, or 0.003, etc.; c can be 0.001, 0.002, or 0.003, etc.; d can be 0.001, 0.002, or 0.003, etc.; e can be 0.003, 0.005, 0.006, 0.007, 0.008, 0.009, or 0.01, etc.

[0030] Thirdly, the present invention provides a high-entropy lithium-rich manganese-based cathode material, wherein the high-entropy lithium-rich manganese-based cathode material is prepared using the high-entropy lithium-rich manganese-based precursor described in the second aspect.

[0031] Fourthly, the present invention provides a method for preparing a high-entropy lithium-rich manganese-based cathode material as described in the third aspect, the method comprising the following steps: The lithium source and the high-entropy lithium-rich manganese-based precursor are mixed at a molar ratio of lithium to metal in the high-entropy lithium-rich manganese-based precursor of 1.22-1.28, and then sintered in an oxygen-containing atmosphere to obtain the high-entropy lithium-rich manganese-based cathode material.

[0032] In this technical solution, the molar ratio of lithium to the metal in the high-entropy lithium-rich manganese-based precursor is 1.22-1.28, for example, it can be 1.22, 1.23, 1.24, 1.25, 1.26, 1.27 or 1.28, etc.

[0033] Preferably, during the preparation of the high-entropy lithium-rich manganese-based material, the sintering temperature is 800℃-900℃, for example, 800℃, 820℃, 840℃, 850℃, 860℃, 870℃, 880℃, or 900℃; the sintering time is 10h-20h, for example, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, or 20h.

[0034] Fifthly, the present invention provides a lithium-ion battery, characterized in that the lithium-ion battery comprises the high-entropy lithium-rich manganese-based cathode material described in the third aspect.

[0035] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0036] Compared with existing technologies, the present invention has the following beneficial effects: This invention combines wet doping and coating during the synthesis of high-entropy lithium-rich manganese-based precursors, avoiding dopant element segregation without affecting the morphology and structure of the precursor. Specifically, easily doped Al and Nb elements are directly wet-doped using co-precipitation, while easily hydrolyzed Ti and Zr elements, and difficult-to-dopant W elements, are uniformly wet-coated. Later, sintering diffuses the coated elements into the precursor, achieving gradient doping. This effectively improves the material's stability, thereby reducing voltage decay and enhancing cycle performance. Attached Figure Description

[0037] Figure 1 and Figure 2 These are scan images of the high-entropy lithium-rich manganese-based precursor prepared in Example 1 at different magnifications. Detailed Implementation

[0038] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0039] The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0040] In this embodiment of the invention, the lithium ratio refers to the molar ratio of lithium element to the metal element in the precursor.

[0041] Example 1 This embodiment provides a method for preparing a high-entropy lithium-rich manganese-based precursor, including the following steps: Step 1: Prepare a mixed solution A of nickel, manganese, aluminum, and niobium with a total metal concentration of 2 mol / L by mixing Ni:Mn:Al:Nb in a molar ratio of 32:67:0.5:0.5. A mixed solution B of titanium oxysulfate and zirconium sulfate with a total metal concentration of 0.005 mol / L was prepared according to the molar ratio of Ti:Zr=1:1. The pH of the solution was adjusted to 0.8 with dilute sulfuric acid to inhibit the dissolution of titanium ions and zirconium ions. Prepare a 0.005 mol / L sodium tungstate solution C; Prepare a 10 mol / L liquid alkali as a precipitant and an 8 mol / L ammonia solution as a complexing agent.

[0042] Step 2: Under nitrogen protection, add mixed solution A, liquid alkali and ammonia water to the reactor in parallel. Adjust the reaction pH to 9.0, ammonia concentration to 1 g / L, temperature to 40℃, and stirring speed to 300 rpm. Stop feeding after the particle size grows to 18 µm.

[0043] Step 3: Add solutions B and C to the reactor in parallel flow. After reacting for 20 hours, stop feeding to obtain the doped hydroxide precursor.

[0044] Step 4: Sinter the doped hydroxide precursor at 600°C for 6 hours in air to obtain the doped oxide precursor, which is the high-entropy lithium-rich manganese-based precursor.

[0045] The chemical formula of the high-entropy lithium-rich manganese-based precursor prepared in this embodiment is Ni. 0.315 Mn 0.669 Al 0.005 Zr 0.0015 W 0.003 Ti 0.0015 Nb 0.005 O.

[0046] Figure 1 These are SEM images of the high-entropy lithium-rich manganese-based precursor prepared in Example 1. Figure 2 The image shows a cross-sectional SEM image of the high-entropy lithium-rich manganese-based precursor prepared in Example 1. As can be seen from the image, the precursor material has high sphericity, fine primary particles, and a large number of pores on the surface and inside.

[0047] This embodiment also provides a method for preparing a high-entropy lithium-rich manganese-based cathode material, including the following steps: Lithium carbonate and a high-entropy lithium-rich manganese-based precursor were mixed uniformly at a lithium ratio of 1.22 and sintered at 900°C for 12 hours in air to obtain a lithium-rich manganese-based cathode material.

[0048] Example 2 This embodiment provides a method for preparing a high-entropy lithium-rich manganese-based precursor, including the following steps: Step 1: Prepare a mixed solution A of nickel, manganese, aluminum, and niobium with a total metal concentration of 2 mol / L by mixing Ni:Mn:Al:Nb in a molar ratio of 38:61:0.3:0.7. A mixed solution B of titanium oxysulfate and zirconium sulfate with a total metal concentration of 0.003 mol / L was prepared according to the molar ratio of Ti:Zr=1:2. The pH of the solution was adjusted to 1 with dilute sulfuric acid to inhibit the dissolution of titanium ions and zirconium ions. Prepare a 0.003 mol / L sodium tungstate solution C; Prepare a 10 mol / L liquid alkali as a precipitant and an 8 mol / L ammonia solution as a complexing agent.

[0049] Step 2: Under nitrogen protection, add mixed solution A, liquid alkali and ammonia water to the reactor in parallel. Adjust the reaction pH to 9.5, ammonia concentration to 2 g / L, temperature to 45℃, stirring speed to 400 rpm, and stop feeding after the particle size grows to 10 µm.

[0050] Step 3: Add solutions B and C to the reactor in parallel flow. After reacting for 15 hours, stop feeding to obtain the doped hydroxide precursor.

[0051] Step 4: Sinter the doped hydroxide precursor at 550°C for 5 hours in air to obtain the doped oxide precursor, which is the high-entropy lithium-rich manganese-based precursor.

[0052] The chemical formula of the high-entropy lithium-rich manganese-based precursor prepared in this embodiment is Ni. 0.378 Mn 0.606 Al 0.003 Zr 0.002 W 0.003 Ti 0.001 Nb 0.007 O.

[0053] This embodiment also provides a method for preparing a high-entropy lithium-rich manganese-based cathode material, including the following steps: Lithium hydroxide and a high-entropy lithium-rich manganese-based precursor were mixed uniformly at a lithium ratio of 1.26 and sintered at 880°C for 15 hours under an oxygen atmosphere to obtain a lithium-rich manganese-based cathode material.

[0054] Example 3 This embodiment provides a method for preparing a high-entropy lithium-rich manganese-based precursor, including the following steps: Step 1: Prepare a mixed solution A of nickel, manganese, aluminum, and niobium with a total metal concentration of 1.5 mol / L by using a molar ratio of Ni:Mn:Al:Nb = 35:64:0.7:0.3. A mixed solution B of titanium oxysulfate and zirconium sulfate with a total metal concentration of 0.002 mol / L was prepared according to the molar ratio of Ti:Zr=1:1. The pH of the solution was adjusted to 0.5 with dilute sulfuric acid to inhibit the dissolution of titanium ions and zirconium ions. Prepare a 0.002 mol / L sodium tungstate solution C; Prepare a 12 mol / L liquid alkali as a precipitant and a 5 mol / L ammonia solution as a complexing agent.

[0055] Step 2: Under nitrogen protection, add mixed solution A, liquid alkali and ammonia water to the reactor in parallel flow. Adjust the reaction pH to 9.2, ammonia concentration to 1.5 g / L, temperature to 50℃, stirring speed to 500 rpm, and stop feeding after the particle size grows to 8 µm.

[0056] Step 3: Add solutions B and C to the reactor in parallel flow. After reacting for 15 hours, stop feeding to obtain the doped hydroxide precursor.

[0057] Step 4: Sinter the doped hydroxide precursor at 575°C for 4.5 h in air atmosphere to obtain the doped oxide precursor, which is also the high-entropy lithium-rich manganese-based precursor.

[0058] The chemical formula of the high-entropy lithium-rich manganese-based precursor prepared in this embodiment is Ni. 0.347 Mn 0.657 Al 0.007 Zr 0.001 W 0.002 Ti 0.001 Nb 0.003 O.

[0059] This embodiment also provides a method for preparing a high-entropy lithium-rich manganese-based cathode material, including the following steps: Lithium carbonate and a high-entropy lithium-rich manganese-based precursor were mixed uniformly at a lithium ratio of 1.25 and sintered at 840°C for 18 hours in air to obtain a lithium-rich manganese-based cathode material.

[0060] Example 4 The difference between this embodiment and Embodiment 1 is that in step 1, dilute sulfuric acid was not used to adjust the pH.

[0061] Example 5 The difference between this embodiment and Embodiment 1 is that in step 3, while solutions B and C are added to the reactor in parallel flow, liquid alkali and ammonia are also added in parallel flow to carry out a co-precipitation reaction.

[0062] Example 6 The difference between this embodiment and Embodiment 1 is that step 4 is not performed in the preparation method of the precursor.

[0063] Comparative Example 1 The difference between this embodiment and Embodiment 1 is that aluminum, niobium, zirconium, tungsten, and titanium elements are all doped by co-precipitation in step 2, without sintering in step 4.

[0064] Battery assembly: The lithium-rich manganese-based cathode materials provided in Example 16 and Comparative Example 1 were weighed and thoroughly mixed with super carbon black and polyvinylidene fluoride (PVDF) in a mass ratio of 95:3:2. The mixture was coated onto aluminum foil and vacuum dried at 100°C for 5 hours. After removal, the mixture was rolled several times on a roller press and cut into discs. These discs were used as the cathode, lithium metal sheets as the anode, and polypropylene microporous membranes as the separators. The electrolyte was 1 mol / L LiPF6 + EC / DMC / EMC. The CR2032 stainless steel button cell was assembled in a glove box filled with argon gas and with a moisture content of less than 0.1 ppm. After standing for 12 hours, its charge and discharge performance was tested.

[0065] Performance testing: Under test conditions of 2.0~4.8V and 0.1C, the ratio of discharge capacity to charge capacity during the first charge and discharge is the first discharge efficiency. Rate performance is evaluated by the ratio of discharge capacity at 8C to 0.2C rates under voltage conditions of 2.0~4.8V. The voltage was evaluated by performing 50 charge-discharge cycles under test conditions of 2.0~4.8V and 0.1C, and the discharge voltage after each cycle was compared with the initial discharge voltage.

[0066] The test results are shown in Table 1.

[0067] Table 1 As shown in Table 1, this invention introduces different types of elements through wet doping and coating, and then uses sintering to allow the coated elements to diffuse into the precursor, which can improve the stability of the material and effectively enhance the electrochemical performance of the high-entropy lithium-rich manganese-based cathode material.

[0068] Meanwhile, a comparison between Examples 1 and 4 shows that using dilute sulfuric acid to adjust the pH can, on the one hand, inhibit the hydrolysis of zirconium and titanium ions to form precipitation, creating a stable solution and preventing the formation of new crystal nuclei due to solid impurities in the solution entering the reaction system. This stabilizes the reaction conditions of the precursor, resulting in more stable and consistent grain growth. On the other hand, it prevents the preferential precipitation of zirconium and titanium ions in the raw materials, thus reducing the doping content in the material. Therefore, it can improve the overall performance of the material.

[0069] A comparison between Example 1 and Example 5 shows that, even with the addition of ammonia as a complexing agent, Zr and Ti precipitate too quickly and the surface coating becomes uneven under strongly alkaline conditions. Furthermore, W cannot form a precipitate under strongly alkaline conditions, thus affecting the final doping effect.

[0070] A comparison between Example 1 and Example 6 shows that pre-firing allows the elements coated on the surface to diffuse into the interior of the material. However, when hydroxide is directly mixed with lithium and sintered, the diffusion process is affected by lithium, leading to segregation and thus affecting the final result.

[0071] The comparison between Example 1 and Comparative Example 1 shows that multi-element synergistic doping can effectively stabilize the material structure, improve first-efficiency and rate performance, and reduce voltage decay.

[0072] The applicant declares that the detailed method of the present invention is illustrated by the above embodiments, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a high-entropy lithium-rich manganese-based precursor, characterized in that, The preparation method includes the following steps: (1) Aluminum-niobium co-doped nickel-manganese precursors were prepared by co-precipitation; Step (1) includes: adding a mixed solution A containing nickel, manganese, aluminum and niobium, a precipitant solution and a complexing agent solution in parallel into a reaction vessel to carry out a co-precipitation reaction to obtain an aluminum-niobium co-doped nickel-manganese precursor; The pH of the coprecipitation reaction in step (1) is 9.0-9.5; (2) A doping coating solution is introduced into the reaction system for preparing the aluminum-niobium co-doped nickel-manganese precursor. The doping coating solution includes zirconium, tungsten and titanium. The co-precipitation reaction is continued to coat the aluminum-niobium co-doped nickel-manganese precursor to obtain the doped precursor. The doping coating solution in step (2) includes a zirconium-titanium mixed solution B and a sodium tungstate solution C, wherein the zirconium-titanium mixed solution B and the sodium tungstate solution C are introduced into the reaction system in a parallel flow manner; Before using the zirconium-titanium mixed solution B, the pH should be adjusted to 0.5-1. (3) Sinter the doped precursor to diffuse the doping elements in the doped precursor and obtain the high-entropy lithium-rich manganese-based precursor. The high-entropy lithium-rich manganese-based precursor prepared by the method has pores on both its surface and interior.

2. The method for preparing the high-entropy lithium-rich manganese-based precursor according to claim 1, characterized in that, The total metal concentration in the mixed solution A is 1 mol / L-3 mol / L.

3. The method for preparing the high-entropy lithium-rich manganese-based precursor according to claim 1, characterized in that, The precipitant solution is liquid alkali, and the concentration of the liquid alkali is 8 mol / L-12 mol / L.

4. The method for preparing the high-entropy lithium-rich manganese-based precursor according to claim 1, characterized in that, The complexing agent solution is ammonia water, and the concentration of the ammonia water is 5 mol / L-8 mol / L.

5. The method for preparing the high-entropy lithium-rich manganese-based precursor according to claim 1, characterized in that, During the coprecipitation reaction described in step (1), the ammonia concentration in the reaction system is 1 g / L - 2 g / L.

6. The method for preparing the high-entropy lithium-rich manganese-based precursor according to claim 1, characterized in that, The temperature of the coprecipitation reaction in step (1) is 40℃-50℃.

7. The method for preparing the high-entropy lithium-rich manganese-based precursor according to claim 1, characterized in that, The coprecipitation reaction in step (1) is accompanied by stirring, and the stirring speed is 300 rpm-500 rpm.

8. The method for preparing the high-entropy lithium-rich manganese-based precursor according to claim 1, characterized in that, The D50 of the aluminum-niobium co-doped nickel-manganese precursor in step (1) is 3µm-18µm.

9. The method for preparing the high-entropy lithium-rich manganese-based precursor according to claim 1, characterized in that, The total metal concentration in the zirconium-titanium mixed solution B is 0.003 mol / L-0.01 mol / L.

10. The method for preparing the high-entropy lithium-rich manganese-based precursor according to claim 1, characterized in that, The concentration of the sodium tungstate solution C is 0.003 mol / L to 0.01 mol / L.

11. The method for preparing the high-entropy lithium-rich manganese-based precursor according to claim 1, characterized in that, The temperature of the coprecipitation reaction in step (2) is 40℃-50℃.

12. The method for preparing the high-entropy lithium-rich manganese-based precursor according to claim 1, characterized in that, The coprecipitation reaction in step (2) takes 10-20 hours.

13. The method for preparing the high-entropy lithium-rich manganese-based precursor according to claim 1, characterized in that, The sintering atmosphere in step (3) is an oxygen-containing atmosphere.

14. The method for preparing the high-entropy lithium-rich manganese-based precursor according to claim 1, characterized in that, The sintering temperature in step (3) is 500℃-600℃.

15. The method for preparing the high-entropy lithium-rich manganese-based precursor according to claim 1, characterized in that, The sintering time in step (3) is 4h-6h.

16. A high-entropy lithium-rich manganese-based precursor, characterized in that, The high-entropy lithium-rich manganese-based precursor is prepared by the method described in any one of claims 1-15, and the high-entropy lithium-rich manganese-based precursor has pores on both its surface and interior.

17. The high-entropy lithium-rich manganese-based precursor according to claim 16, characterized in that, The chemical formula of the high-entropy lithium-rich manganese-based precursor is Ni. x Mn y Al a Zr b W c Ti d Nb e O, where 0.3≤x≤0.4, 0.6≤y≤0.7, 0.001≤a≤0.01, 0.001≤b≤0.003, 0.001≤c≤0.003, 0.001≤d≤0.003, 0.003≤e≤0.01, and x+y+a+b+c+d+e=1.

18. A high-entropy lithium-rich manganese-based cathode material, characterized in that, The high-entropy lithium-rich manganese-based cathode material is prepared using the high-entropy lithium-rich manganese-based precursor described in claim 16 or 17.

19. A method for preparing the high-entropy lithium-rich manganese-based cathode material as described in claim 18, characterized in that, The preparation method includes the following steps: mixing a lithium source with the high-entropy lithium-rich manganese-based precursor at a molar ratio of lithium to metal in the high-entropy lithium-rich manganese-based precursor of 1.22-1.28, and then sintering the mixture in an oxygen-containing atmosphere to obtain the high-entropy lithium-rich manganese-based cathode material.

20. The method for preparing the high-entropy lithium-rich manganese-based cathode material according to claim 19, characterized in that, In the preparation process of the high-entropy lithium-rich manganese-based material, the sintering temperature is 800℃-900℃ and the sintering time is 10h-20h.

21. A lithium-ion battery, characterized in that, The lithium-ion battery includes the high-entropy lithium-rich manganese-based cathode material as described in claim 18.

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