A lithium-rich manganese-based layered positive electrode material, a preparation method and application thereof

Abstract

The application discloses a lithium-rich manganese-based layered positive electrode material and a preparation method and application thereof. The lithium-rich manganese-based layered positive electrode material disclosed by the application does not contain cobalt and is composed of lithium layers and transition metal oxide layers which are alternately stacked; the lithium layer contains 3-9 at% of cation inversion which is formed by transition metal entering the lithium layer to occupy the lithium ion position, and the cation inversion exists in disordered nanodomain regions. The lithium-rich manganese-based layered positive electrode material disclosed by the application has a simple preparation method, can be directly produced by using a sol-gel production device, does not need to additionally increase equipment, and has low raw material cost; more importantly, the lithium layer of the lithium-rich manganese-based layered positive electrode material contains 3-9 at% of cation inversion, the disordered nanodomain region formed by the cation inversion has rich lithium ion transmission channels, the accumulation of stress in the cycle process can be reduced, the strain between lattices can be maximally reduced, and therefore the cycle stability and electrochemical performance of the lithium-rich manganese-based layered positive electrode material can be remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of positive electrode materials, in particular to a lithium-rich manganese-based layered positive electrode material and a preparation method and application thereof. BACKGROUND

[0002] With the transformation of the automobile industry to electrification, the lithium-ion battery industry is rapidly developing, and the demand for sustainable positive electrode materials with low cost and high energy density is increasingly urgent. At present, cobalt, as a key component of widely used commercial positive electrode materials (such as LiCoO2), is facing serious resource shortage and high cost problems. In recent years, in order to reduce the cost pressure, the development of various low-cobalt or cobalt-free positive electrode materials has become a research hotspot, in order to realize the optimization of cost and resources on the premise of not sacrificing the performance of the battery. However, designing cobalt-free and high-performance lithium-ion layered positive electrode materials still faces great challenges. In the development process of cobalt-free lithium-rich positive electrode materials with higher energy density, their commercial application is limited by the problems of voltage and energy attenuation, and these problems are usually closely related to the migration of transition metals and irreversible structural degradation.

[0003] The traditional methods for enhancing the electrochemical performance of lithium-rich manganese-based (LMR) layered positive electrode materials include cation doping, surface engineering and phase structure control, although these methods have achieved certain results to some extent; however, compared with commercial lithium cobalt oxide and nickel-based oxide positive electrodes, LMR layered positive electrode materials exhibit slower and asymmetric redox processes in terms of oxygen redox reactions and kinetic suitability.

[0004] Therefore, how to improve the cycle stability and electrochemical performance of lithium-rich manganese-based layered positive electrode materials is still a research focus and difficulty in the technical field of lithium-ion battery positive electrode materials. SUMMARY

[0005] The purpose of the present application is to provide an improved lithium-rich manganese-based layered positive electrode material and a preparation method and application thereof.

[0006] In order to achieve the above-mentioned purpose, the following technical solutions are adopted in the present application:

[0007] One aspect of the present application discloses a lithium-rich manganese-based layered positive electrode material, which does not contain cobalt and is composed of lithium layers and transition metal oxide layers stacked alternately; the lithium layer contains 3-9 at% of cation inversion, which exists in disordered nanodomain regions, and the cation inversion is formed by transition metals occupying lithium ion positions to enter the lithium layer.

[0008] It should be noted that, compared with the existing lithium-rich manganese-based positive electrode material, the cation inversion in the lithium layer of the lithium-rich manganese-based layered positive electrode material of the present application can be as high as 3-9 at%, i.e. 3-9% atomic percentage, and the cation inversion exists in the disordered nanodomain region, which can obtain abundant lithium ion transmission channels, reduce the accumulation of stress in the cycle process, and maximize the reduction of the strain between the lattices, thereby significantly improving the cycle stability and electrochemical performance of the lithium-rich manganese-based layered positive electrode material.

[0009] In an implementation form of the present application, the main components of the transition metal oxide layer are manganese and nickel; or the main components of the transition metal oxide layer are manganese, nickel and aluminum.

[0010] In an implementation form of the present application, the lithium-rich manganese-based layered positive electrode material is a secondary microparticle composed of primary nanoparticles.

[0011] In an implementation form of the present application, the size of the primary nanoparticles is 50-800 nanometers, and the size of the secondary microparticles is 1-20 micrometers.

[0012] Another aspect of the present application discloses a positive electrode tab containing the lithium-rich manganese-based layered positive electrode material of the present application.

[0013] Still another aspect of the present application discloses the application of the lithium-rich manganese-based layered positive electrode material of the present application or the positive electrode tab of the present application in a power lithium battery or a 3C consumer electronic lithium ion battery.

[0014] Still another aspect of the present application discloses a lithium ion battery using the positive electrode tab of the present application.

[0015] Still another aspect of the present application discloses a preparation method of the lithium-rich manganese-based layered positive electrode material of the present application, which comprises replacing part of the lithium source with lithium fluoride and / or replacing part of the transition metal source with a transition metal fluoride in the process of preparing the lithium-rich manganese-based layered positive electrode material by using a sol-gel method; under the premise of introducing fluorine, the proportion of the disordered domain in the lithium-rich manganese-based layered positive electrode material is adjusted by adjusting the proportion of the transition metal, so that the lithium layer of the prepared lithium-rich manganese-based layered positive electrode material contains 3-9 at% of cation inversion.

[0016] It should be noted that the present inventors have found that, under the premise of introducing fluorine, adjusting the proportion of manganese, nickel and / or aluminum elements in the transition metal can obtain more cation inversion in the lithium layer, i.e. 3-9 at%, while the existing preparation method usually only has less than 1 at% of cation inversion; this makes the lithium-rich manganese-based layered positive electrode material prepared by the present application have a special lithium ion seepage network of ordered-disordered nanodomain region, thereby improving the lithium ion migration ability and obtaining a layered positive electrode material with high cycle stability, so that the cobalt-free layered positive electrode material of the present application exhibits excellent electrochemical performance.

[0017] It should be further noted that the addition of fluorine, i.e. replacing part of the lithium source with lithium fluoride and / or replacing part of the transition metal source with a transition metal fluoride, and the regulation of the ratio between aluminum and nickel manganese are two prerequisites for obtaining materials with different degrees of disorder. The regulation of the content of fluorine will not help to regulate the degree of disorder, but without fluorine, the positive electrode material with a disordered phase cannot be obtained. One of the keys of the preparation method of the present application is that a fluorine source is introduced in the synthesis stage. For the nickel manganese aluminum system, the present application research finds that by this synthesis method, a disordered domain can be obtained.

[0018] In an implementation manner of the present application, lithium fluoride is used to replace part of the lithium source and / or aluminum fluoride is used to replace part of the aluminum source, and fluorine is introduced through the two substances to induce the formation of a disordered phase.

[0019] In an implementation manner of the present application, the disordered nanodomain of the lithium-rich manganese-based layered positive electrode material can be regulated by adjusting the ratio of aluminum and nickel manganese elements in the transition metal layer under the premise that the lithium content is unchanged, i.e. with the increase of the proportion of aluminum elements, the degree of disorder increases, and the amount of corresponding cation inversion also increases.

[0020] It should be noted that the present application research finds that when the proportion of aluminum elements in the transition metal layer is adjusted to 8-12%, a lithium-rich manganese-based layered positive electrode material with 3-9 at% of cation inversion can be obtained.

[0021] In an implementation manner of the present application, the preparation method of the present application comprises the following steps:

[0022] (1) according to the lithium-rich manganese-based layered positive electrode material to be synthesized, the lithium source and the transition metal source are weighed according to the sol-gel method for synthesizing the precursor; and lithium fluoride is used to replace part of the lithium source, and / or a transition metal fluoride is used to replace part of the transition metal source; the source materials are mixed with a complexing agent to prepare a gel mixture;

[0023] (2) the gel mixture is calcined at 400-600°C for 3-24 hours in an oxygen or air atmosphere to complete the preliminary sintering;

[0024] (3) the product of the preliminary sintering is ground, and then calcined at 700-1100°C for 3-24 hours in an oxygen or air atmosphere to obtain the lithium-rich manganese-based layered positive electrode material.

[0025] In an implementation form of the application, the amount of lithium fluoride and / or transition metal fluoride replacement is 15wt%-25wt% of the lithium source and / or the transition metal source; that is, when lithium fluoride or transition metal fluoride is used alone to replace the corresponding lithium source or transition metal source, the lithium fluoride or transition metal fluoride replaces 15wt%-25wt% of the lithium source or transition metal source with lithium fluoride or transition metal fluoride; if lithium fluoride and transition metal fluoride are used simultaneously to replace the corresponding lithium source and transition metal source, the total amount of lithium fluoride and transition metal fluoride replacement is 15wt%-25wt% of the total amount of lithium source and transition metal source.

[0026] It should be noted that the introduction of fluorine source is a necessary condition for the formation of disordered phase. In the process of synthesizing lithium-rich manganese-based layered cathode material by sol-gel method, HF and the like are generated, which will cause the loss of F. Therefore, the application creatively introduces about 20wt% of fluorine in the early stage, that is, the amount of lithium fluoride and / or transition metal fluoride replacement is 15wt%-25wt%, which can ensure the generation of disordered phase. Controlling the content of fluorine will not help to control the degree of disorder, but without fluorine, the cathode material with disordered phase cannot be obtained. It can be understood that if the amount of fluorine is too small, the disordered phase may not be formed; if it is too much, it may induce the formation of other non-layered phases during the synthesis process. In general, fluorine is a prerequisite for the formation of disordered phase, and too much or too little is not conducive to the formation of such disordered phase. For the technical solution of synthesizing lithium-rich manganese-based layered cathode material by sol-gel method, the amount of lithium fluoride and / or transition metal fluoride replacement is preferably 15wt%-25wt%.

[0027] Thanks to the above technical solution, the application has the following advantages:

[0028] The lithium-rich manganese-based layered cathode material of the application has a simple preparation method and can be directly produced by using sol-gel production equipment without the need for additional equipment, thereby reducing the cost of raw materials. More importantly, the lithium layer of the lithium-rich manganese-based layered cathode material contains 3-9at% of cation inversion, and the cation inversion exists in the disordered nanodomain region, has abundant lithium ion transmission channels, can reduce the accumulation of stress during the cycle process, and maximizes the reduction of lattice strain, thereby significantly improving the cycle stability and electrochemical performance of the lithium-rich manganese-based layered cathode material. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 FIG. 1 is a structural schematic diagram of the layered cathode material with ordered-disordered nanodomain region in the embodiment of the application;

[0030] Figure 2 FIG. 3 is a scanning electron microscope image of the lithium-rich manganese-based layered cathode material prepared in Example 1 of the application;

[0031] Figure 3is a transmission electron microscope result diagram of a lithium-rich manganese-based layered cathode material prepared in Example 1 of the present application;

[0032] Figure 4 is a coulombic and energy efficiency result diagram of a lithium-rich manganese-based layered cathode material prepared in Example 1 of the present application in a voltage range of 2-4.8V at a current of 0.1C;

[0033] Figure 5 is a powder diffraction refinement result diagram of a lithium-rich manganese-based layered cathode material prepared in Example 1 of the present application;

[0034] Figure 6 is a cycle performance result diagram of a lithium-rich manganese-based layered cathode material prepared in Example 1 of the present application in a voltage range of 2-4.8V at a current of C / 2 rate;

[0035] Figure 7 is a cycle performance result diagram of a lithium-rich manganese-based layered cathode material prepared in Examples 1 to 3 of the present application in a voltage range of 2-4.8V at a current of 0.1C rate;

[0036] Figure 8 is a cycle performance result diagram of a lithium-rich manganese-based layered cathode material prepared in Example 3 of the present application in a voltage range of 2-4.8V at a current of 0.1C rate;

[0037] Figure 9 is a powder diffraction refinement result diagram of a lithium-rich manganese-based layered cathode material prepared in Examples 2 and 3 of the present application. DETAILED DESCRIPTION

[0038] The voltage and energy attenuation of lithium-rich manganese-based layered cathode materials are usually closely related to the migration of transition metals and irreversible structural degradation. The present inventors have found that the electrochemical attenuation of lithium-rich manganese-based layered cathode materials is closely related to the evolution of their internal structure; in particular, the lattice strain in the heterogeneous composite structure is the main reason for the structural degradation of lithium-rich manganese-based cathode materials; in such materials, the components of the layered phase structure usually have a non-uniform distribution of lattice, leading to an asynchronous structural evolution during charging and discharging, and significant lattice strain at the phase interface; the evolution of these heterogeneous structures causes a unidirectional tensile strain around the defects, exacerbating the migration of transition metals under high voltage conditions and the irreversible attenuation of structure and electrochemical performance. Traditional methods of enhancing the electrochemical performance of lithium-rich manganese-based layered cathode materials are difficult to effectively control the reaction heterogeneity and lattice strain during the cycle process. Moreover, LMR layered cathode materials exhibit a slow and asymmetric redox process in terms of oxygen redox reaction and kinetic suitability, which is believed to be caused by the kinetic characteristics of structural heterogeneity.

[0039] Therefore, the inventors of this application creatively propose that the structural strain of lithium-rich manganese-based substrate cathode materials can be suppressed during cycling through innovative structural design, thereby improving the cycling stability and electrochemical performance of lithium-rich manganese-based substrate cathode materials.

[0040] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. The following embodiments are merely illustrative of this application and should not be construed as limiting the scope of this application.

[0041] Example 1

[0042] (1) According to the designed molecular formula Li[Li 0.25 Mn 0.5 Ni 1 / 6 Al 1 / 12 ]O 1.75 F 0.25 Accurately weigh the required raw materials, all of which are acetates in this example. 20 wt% of lithium salt is replaced with lithium fluoride, and 2 wt% lithium salt is added in excess. Citric acid and polyvinylpyrrolidone are added as complexing agents in a 1:3 ratio, maintaining a 2:1 molar ratio of complexing agent to transition metal. First, dissolve LiF in a suitable amount of dilute nitric acid, then add the remaining materials in sequence, and finally add deionized water. React the mixture in a 90°C oil bath, stirring until a gel forms.

[0043] (2) Obtain the product by high-temperature solid-state sintering: Calcine the gel obtained above in air at 500°C for 6 hours, take it out and grind it, then calcine it at 800°C for 12 hours and cool it down naturally to obtain the polycrystalline material, namely the lithium-rich manganese-based solid cathode material in this example.

[0044] The lithium-rich manganese-based substrate cathode material prepared in this example was observed using scanning electron microscopy, and the results are as follows: Figure 2 As shown, Figure 2 The scale is 1 micrometer. Figure 2 The results showed that dense secondary particles with an average particle size of 3 micrometers were prepared in this example.

[0045] The lithium-rich manganese-based substrate cathode material prepared in this example was observed using transmission electron microscopy, and the results are as follows: Figure 3 As shown. Figure 3 The results show that the lithium-rich manganese-based layered cathode material prepared in this example possesses ordered-disordered nanodomain regions and exhibits a coherent lattice, i.e., a symbiotic structure. This structure is unique, as it is generally ordered in layered cathode materials. A schematic diagram of the ordered-disordered nanodomain region layered cathode material in this example is shown below. Figure 1 As shown.

[0046] X-ray diffraction analysis was performed on the lithium-rich manganese-based substrate cathode material prepared in this example, and the results are as follows: Figure 5As shown; based on the structural refinement of the X-ray diffraction pattern, it was determined that the lithium-rich manganese-based substrate cathode material prepared in this example contains 3.8 at% of transition metal cations in the lithium layer.

[0047] Electrochemical testing: The lithium-rich manganese-based substrate cathode material, conductive carbon black, and binder (PVDF) prepared in this example were mixed at a mass ratio of 8:1:1 and ground uniformly in a mortar to prepare the cathode sheet. The active material loading was controlled at approximately 5 mg / cm³. 2 The positive electrode was assembled into a 2032 coin cell to form a lithium half-cell. This half-cell used a Celgard 2325 separator and a 1.2 mol / L GEN II electrolyte (LiPF6 dissolved in a 3:7 volume ratio EC / EMC mixed solvent). The electrolyte was applied at 2-4.8 V (vs. Li). + Cyclic testing of the half-cell was conducted within the / Li) voltage range. Meanwhile, the same conventional lithium-rich manganese-based substrate cathode material was prepared using the same source material as a control, i.e., the lithium salt was not replaced with 20wt% lithium fluoride, and all other parameters and conditions were the same; therefore, the transition metal and lithium content in the control lithium-rich manganese-based substrate cathode material was consistent, the only difference being the amount of cation trans sites.

[0048] The coulombic and energy efficiency results of this example of a lithium-rich manganese-based substrate cathode material at 0.1C current within a voltage range of 2-4.8V are as follows: Figure 4 As shown, Figure 4 In the diagram, the orange curve represents the result of the lithium-rich manganese-based substrate cathode material in this example, while the gray curve represents the result of the lithium-rich manganese-based substrate cathode material used as a control.

[0049] Figure 4 The results show that the lithium-rich manganese-based substrate cathode material in this example improves the energy efficiency and coulombic efficiency of the first cycle through the construction of this ordered-disordered nanodomain structure.

[0050] The cycling performance results of this example of a lithium-rich manganese-based substrate cathode material at a C / 2 rate current within a voltage range of 2-4.8V are as follows: Figure 6 As shown. At the same time, this example also compared and tested the cycle performance of the LMNAO cathode material under the same conditions, i.e. Figure 6 The black curve in the image.

[0051] Figure 6 The results show that the lithium-rich manganese-based substrate cathode material in this example still maintains 98.01% capacity retention after 200 cycles, demonstrating excellent long-cycle stability; while the general material LMNAO only retains 67.69% capacity retention after 200 cycles, showing significant degradation.

[0052] Example 2

[0053] (1) According to the designed formula Li[Li 0.245 Mn 0.49 Ni 0.1633 Al 0.1017 ]O 1.75 F 0.25 , the required raw materials are accurately weighed, in this example, acetate, 20wt% of which is replaced by lithium fluoride, and the lithium salt is in excess of 2wt%. Citric acid and polyvinylpyrrolidone are used as complexing agents, and are added in a ratio of 1:3, so that the molar ratio of complexing agent to transition metal is 2:1. LiF is first dissolved in an appropriate amount of dilute nitric acid, and then the remaining materials are added in order, and finally an appropriate amount of deionized water is added. The mixture is stirred in an oil bath at 90°C until a gel is formed.

[0054] (2) The product is obtained by high-temperature solid-phase sintering: the gel obtained above is calcined at 500°C in air for 6 hours, then ground and calcined at 800°C for 12 hours, and then naturally cooled to obtain a polycrystalline material, i.e. the lithium-rich manganese-based layered positive electrode material of this example.

[0055] The lithium-rich manganese-based layered positive electrode material prepared in this example is observed by scanning electron microscopy, and the results show that the secondary particles prepared in this example have a compact structure with an average particle size of about 3 microns. Transmission electron microscopy shows that the lithium-rich manganese-based layered positive electrode material prepared in this example has ordered-disordered nanodomain regions, and shows a coherent lattice.

[0056] The structure refinement of the X-ray diffraction pattern of the lithium-rich manganese-based layered positive electrode material prepared in this example is shown in Figure 9 According to the structure refinement of the X-ray diffraction pattern, it is determined that the lithium layer of the lithium-rich manganese-based layered positive electrode material prepared in this example contains 6.2at% of transition metal cation inversion.

[0057] Electrochemical test: the lithium-rich manganese-based layered positive electrode material prepared in this example, conductive carbon black and binder (PVDF) are mixed in a mass ratio of 8:1:1, and are uniformly ground in a mortar to prepare a positive electrode sheet, and the active material loading is controlled at about 5mg / cm 2 . The positive electrode sheet is assembled in a 2032 type button cell to form a lithium half-cell. The half-cell uses a Celgard 2325 separator, and uses a 1.2mol / L GEN II electrolyte (LiPF6 dissolved in a volume ratio of 3:7 EC / EMC mixed solvent). The half-cell is tested in a voltage range of 2-4.8V (vs Li + / Li).

[0058] The cycle performance results of the lithium-rich manganese-based layered positive electrode material prepared in this example at a current rate of 0.1C in a voltage range of 2-4.8V are shown in Figure 7 .Figure 7 The result of the middle MD curve, i.e. the result of the example, Figure 7 The result shows that by regulating the degree of disorder, the example can obtain higher capacity.

[0059] Example 3

[0060] (1) According to the designed molecular formula Li[Li 0.24 Mn 0.48 Ni 0.16 Al 0.12 ]O 1.75 F 0.25 , the required raw materials are accurately weighed, all of which are acetate salts in the example, 20wt% of the lithium salt is replaced by lithium fluoride, and the lithium salt is in excess by 2wt%. Citric acid and polyvinylpyrrolidone are used as complexing agents, and are added in a ratio of 1:3, so that the molar ratio of complexing agent to transition metal is 2:1. First, LiF is dissolved by mixing with an appropriate amount of dilute nitric acid, then the remaining materials are added in order, and finally an appropriate amount of deionized water is added. The mixture is stirred in an oil bath at 90°C until a gel is formed.

[0061] (2) The product is obtained by high-temperature solid-phase sintering: the gel obtained above is calcined at 500°C in air for 6 hours, then ground and calcined at 800°C for 12 hours, and then naturally cooled to obtain a polycrystalline material, i.e. the lithium-rich manganese-based layered positive electrode material of the example.

[0062] The lithium-rich manganese-based layered positive electrode material prepared in the example is observed by scanning electron microscopy, and the results show that the example has prepared a dense secondary particle with an average particle size of about 3 microns. Transmission electron microscopy observation shows that the lithium-rich manganese-based layered positive electrode material prepared in the example has ordered-disordered nanodomain regions and shows a coherent lattice.

[0063] The structure refinement graph of the X-ray diffraction pattern of the lithium-rich manganese-based layered positive electrode material prepared in the example is shown in Figure 9 According to the structure refinement of the X-ray diffraction pattern, it is determined that in the lithium-rich manganese-based layered positive electrode material prepared in the example, the lithium layer contains 8.3at% of transition metal cation inversion.

[0064] Electrochemical test: the lithium-rich manganese-based layered positive electrode material prepared in the example, conductive carbon black and binder (PVDF) are mixed in a mass ratio of 8:1:1, uniformly ground in a mortar, and an electrode sheet is prepared, with an active material loading of about 5mg / cm 2 . The electrode sheet is assembled in a 2032 type button cell to form a lithium half-cell. The half-cell uses a Celgard 2325 separator and a 1.2mol / L GEN II electrolyte (LiPF6 dissolved in a volume ratio of 3:7 EC / EMC mixed solvent). The half-cell is tested in the voltage range of 2-4.8V (vs Li +The half-cells were cycled in the voltage range of 2-4.8V.

[0065] The results of the cycle performance of the lithium-rich manganese-based layered positive electrode material prepared in this example in the voltage range of 2-4.8V at a 0.1C rate current are shown in FIG. Figure 7 and Figure 8 . Figure 7 is a comparison chart of three lithium-rich manganese-based layered positive electrode materials prepared in Examples 1-3, in which LD is the lithium-rich manganese-based layered positive electrode material of Example 1, MD is the lithium-rich manganese-based layered positive electrode material of Example 2, and HD is the lithium-rich manganese-based layered positive electrode material of Example 3. Figure 7 The results show that the lithium-rich manganese-based layered positive electrode material has a higher capacity as the anti-site amount of transition metal cations in the lithium layer increases, i.e., the lithium-rich manganese-based layered positive electrode material of Example 3 has a higher capacity.

[0066] Figure 8 is a chart of the cycle performance of the positive electrode material with a high degree of disorder in Example 3 in the voltage range of 2-4.8V at a 0.1C rate current. Figure 8 The results show that the lithium-rich manganese-based layered positive electrode material prepared in this example has a retention rate of 99.5% after 100 cycles for the material with the highest capacity in Figure 7 , and can achieve excellent long cycle stability, which is not achievable in existing lithium-rich manganese-based materials.

[0067] The above uses specific examples to illustrate the present application, which is only used to help understand the present application and does not limit the present application. For those skilled in the art to which the present application belongs, according to the idea of the present application, several simple deductions, deformations or substitutions can be made.

Claims

1. A lithium-rich manganese-based layered cathode material, characterized in that: The lithium-rich manganese-based layered positive electrode material does not contain cobalt and is composed of lithium layers and transition metal oxide layers alternately stacked. The lithium layer contains 3-9 at% of cation anti-sites, which exist in disordered nanodomain regions, and the cation anti-sites are formed by transition metals occupying lithium ion positions.

2. The lithium-rich manganese-based layered cathode material of claim 1, wherein: The main component of the transition metal oxide layer is manganese and nickel. Or the main component of the transition metal oxide layer is manganese, nickel and aluminum.

3. The lithium-rich manganese-based layered cathode material of claim 1 or 2, wherein: The lithium-rich manganese-based layered positive electrode material is composed of secondary microparticles composed of primary nanoparticles.

4. The lithium-rich manganese-based layered cathode material of claim 3, wherein: The size of the primary nanoparticles is 50-800 nanometers, and the size of the secondary microparticles is 1-20 micrometers.

5. A positive electrode sheet characterized by comprising: The lithium-rich manganese-based layered positive electrode material according to any one of claims 1-4.

6. Use of the lithium-rich manganese-based layered positive electrode material according to any one of claims 1-4 or the positive electrode sheet according to claim 5 in a power lithium battery or a 3C consumer electronic lithium ion battery.

7. A lithium-ion battery, characterized by: The positive electrode sheet according to claim 5 is used.

8. Process for the preparation of the lithium-rich manganese-based layered positive material according to any one of claims 1 to 4, characterized in that: The process for preparing the lithium-rich manganese-based layered positive electrode material by the sol-gel method includes replacing part of the lithium source with lithium fluoride and / or replacing part of the transition metal source with transition metal fluoride. Under the premise of introducing fluorine, by adjusting the proportion of transition metals, the proportion of disordered domains in the lithium-rich manganese-based layered positive electrode material is adjusted, so that the lithium layer of the prepared lithium-rich manganese-based layered positive electrode material contains 3-9 at% of cation anti-sites.

9. The method of claim 8, wherein: The process includes the following steps, (1) according to the lithium-rich manganese-based layered positive electrode material to be synthesized, the lithium source and the transition metal source are weighed according to the sol-gel method for synthesizing the precursor; and lithium fluoride is used to replace part of the lithium source, and / or transition metal fluoride is used to replace part of the transition metal source; the source materials are mixed with a complexing agent to prepare a gel mixture; (2) the gel mixture is calcined at 400-600°C for 3-24 hours in an oxygen or air atmosphere to complete the preliminary sintering; (3) the product of the preliminary sintering is ground, and then calcined at 700-1100°C for 3-24 hours in an oxygen or air atmosphere to obtain the lithium-rich manganese-based layered positive electrode material.

10. The production method according to claim 8 or 9, characterized in that: The amount of lithium fluoride and / or transition metal fluoride replacement is 15wt%-25wt% of the lithium source and / or the transition metal source.

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