A lithium-rich manganese-based positive electrode material coated with a surfactant and a preparation method thereof

Abstract

The application belongs to the technical field of lithium ion battery materials, and discloses a kind of cationic surfactant coated modified lithium-rich manganese-based positive electrode material and its preparation method, first, cationic surfactant ethanol solution is prepared by dissolution, and lithium-rich manganese-based positive electrode material is dispersed in ethanol to prepare lithium-rich manganese-based positive electrode material dispersion liquid;Then the cationic surfactant ethanol solution is added to the lithium-rich manganese-based positive electrode material at a constant speed, and the mixture is fully mixed to obtain a mixed solution;Finally, the mixed solution is treated by water bath heating solvent evaporation, and the cationic surfactant coated modified lithium-rich manganese-based positive electrode material is obtained by low-temperature heat treatment.The application process is simple and easy to operate;The prepared lithium-rich manganese-based positive electrode material coating layer grows uniformly, and the composite effect is good.By coating the cationic surfactant on the lithium-rich manganese-based material, the surface side reaction caused by the contact between the material and the electrolyte is greatly reduced, thereby improving the cycle stability of the material in the electrochemical process.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion battery materials, and particularly relates to a surfactant-coated modified lithium-rich manganese-based positive electrode material and a preparation method thereof. Background Art

[0002] Lithium-ion batteries are widely used in the 3C (3D consumer electronics) sector, new energy vehicles, and large-scale energy storage due to their high output voltage, high energy density, and environmental friendliness. As a member of the lithium-ion battery cathode material family, lithium-rich manganese-based materials, due to their high specific capacity, are expected to become a new commercial lithium-ion battery cathode material to replace ternary cathode materials. However, during cycling at high voltages, lithium-rich manganese-based materials experience severe corrosion of the cathode material by the electrolyte, which in turn triggers irreversible oxygen loss and transition metal dissolution, leading to structural collapse and capacity decay of the material under high voltage conditions.

[0003] Current solutions to the interfacial issues faced by lithium-rich manganese-based cathode materials primarily involve constructing an artificial interface layer on the cathode particles to modify the material surface and reduce side reactions between the material and the electrolyte. Furthermore, methods such as electron layer deposition and chemical vapor deposition are often used to uniformly coat the cathode material surface. However, these methods are complex and costly, making them difficult to commercialize.

[0004] Therefore, the present invention utilizes a cationic surfactant as a coating material, and the coating material is uniformly coated on the lithium-rich manganese-based positive electrode material through a simple solution method, and through a subsequent heat treatment process, the coating material is firmly bonded to the surface of the lithium-rich manganese-based material, so that the coating material protects the surface structure of the material for a long time during the circulation process. On the other hand, since the crystal size of the cationic surfactant is closely related to the solvent volatilization rate, the crystal size of the surfactant can be controlled by controlling the solvent rate, and the thickness of the coating layer can be controlled by controlling the quality of the cationic surfactant. This structure inhibits the side reactions of the lithium-rich manganese-based surface under high pressure conditions and inhibits oxygen precipitation. At the same time, the addition of the cationic surfactant reduces the surface tension of the solvent, increases the contact area between the solution and the positive electrode material particles, thereby achieving uniform coating of the coating material on the positive electrode material. In addition, the introduction of a small amount of polymer and lithium salt is beneficial to increase the mechanical strength and ionic conductivity of the coating layer, thereby increasing the coating effect. This method provides an effective reference for the practical application of material modification methods in the future. Summary of the Invention

[0005] In view of the above problems existing in the prior art, a cationic surfactant-coated lithium-rich manganese-based positive electrode material and a preparation method thereof are provided.

[0006] The purpose of the present invention is specifically achieved through the following technical solutions:

[0007] A method for preparing a surfactant-coated modified lithium-rich manganese-based positive electrode material comprises the following steps:

[0008] (1) dissolving a certain amount of surfactant, polymer, and lithium salt in a solvent and fully dissolving and dispersing them to obtain solution A;

[0009] (2) adding a certain amount of lithium-rich manganese-based cathode material to a solvent and fully stirring and dispersing the material under ultrasound to obtain solution B;

[0010] (3) adding solution A to solution B at a uniform rate over a certain period of time, and continuously stirring for a certain period of time to obtain a mixed solution, heating the mixed solution in an oil bath to evaporate all the solvent, collecting and grinding the solid particles, and heat-treating the solid particles under a protective atmosphere to obtain a surfactant-coated modified lithium-rich manganese-based positive electrode material.

[0011] Preferably, the surfactant in step (1) is at least one of lithium dodecyl sulfate, hexadecyltrimethylammonium bromide, and lithium dodecylbenzenesulfonate.

[0012] Preferably, the polymer in step (1) is at least one of PVDF, PVDF-HFP, and PVDF-CTFE.

[0013] Preferably, the lithium salt described in step (1) is at least one of LiFSI, LiPF6, and LiNO3.

[0014] Preferably, the solvent in step (1) is at least one of DMF and NMP.

[0015] Preferably, the concentration of the surfactant in step (1) is 0.4-1 g / L, and the mass ratio of the surfactant, polymer and lithium salt is 1:0.02-0.10:0.02-0.10.

[0016] Preferably, the solvent and amount in step (2) are the same as those in step (1).

[0017] Preferably, the amount of lithium-rich manganese-based material added in step (2) is 15-50 g / L.

[0018] Preferably, the time for uniformly adding solution A to solution B in step (3) is 15-45 minutes, the stirring reaction time is 2-4 hours, and the reaction temperature is 15-25°C.

[0019] Preferably, the heating and evaporation time in the oil bath in step (3) is 4-6 hours.

[0020] Preferably, the solid particles described in step (3) are treated under a protective atmosphere, which is one of argon and nitrogen, and the temperature is increased to 150-200°C at 5°C / min and kept warm for 4-6h.

[0021] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0022] The present invention utilizes cationic surfactants as coating materials, and controls the content of the coating and the crystal size of the coating through a simple liquid phase coating method, so as to coat the coating on the lithium-rich manganese-based surface. Cationic surfactants act as coating agents to prevent the lithium-rich manganese-based particles from contacting the electrolyte, thereby reducing side reactions on the surface of the lithium-rich manganese-based particles. On the other hand, the present invention utilizes the advantage of cationic surfactants in reducing the surface tension of the liquid, thereby enhancing the wettability of the liquid on the solid surface, and achieves the purpose of uniformly coating the lithium-rich manganese-based positive electrode particles through a simple liquid phase coating method. In addition, the application of a small amount of polymers and lithium salts makes the coating layer have higher mechanical strength and greater ionic conductivity. This will provide an effective reference for the practical application of uniformly coating positive electrode materials with coatings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the SEM morphology of Example 1 of the present invention. Figure 2 1 and 2 are cycle performance diagrams of Example 1, Comparative Example 1, and Comparative Example 2 of the present invention. Figure 3 These are the EIS test results after cycling of Example 1, Comparative Example 1, and Comparative Example 2. DETAILED DESCRIPTION

[0024] Example 1

[0025] (1) Dissolve 0.05 g of lithium dodecyl sulfate, 0.005 g of PVDF-HFP, and 0.005 g of LiFSI in 100 ml of DMF and fully dissolve and disperse them to obtain solution A;

[0026] (2) adding 3 g of lithium-rich manganese-based material to 100 ml of DMF and stirring and dispersing the mixture under ultrasound to obtain solution B;

[0027] (3) Solution A was added to solution B at a uniform rate within 30 minutes, the solution temperature was controlled at 20°C, and stirring was continued for 3 hours to obtain a mixed solution, which was heated in an oil bath for 5 hours to evaporate all the solvent, and the solid particles were collected and ground. The solid particles were heat-treated in an argon atmosphere, heated to 180°C at a rate of 5°C / min, and kept warm for 5 hours, and naturally cooled to room temperature to obtain a surfactant-coated modified lithium-rich manganese-based positive electrode material.

[0028] The prepared material was mixed with the conductive agent acetylene black (AB) and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. N-methylpyrrolidone (NMP) was used as the solvent and the mixture was stirred in a small beaker at 800 rpm for 2 hours to obtain a slurry. The slurry was coated on the current collector aluminum foil using an automatic coater, placed flat on tempered glass, and dried in a vacuum drying oven at 85°C for 4 hours. The sheets were punched into electrodes with a diameter of 12 mm and dried in a vacuum drying oven at 105°C for 4 hours. The electrodes were then placed in an argon atmosphere in a glove box with a moisture and oxygen content of less than 0.1 ppm for 4 hours to reduce moisture adsorption during transfer. The lithium sheet was cut into a circular piece with a diameter of 19 mm as the negative electrode, the PP separator was cut into a circular piece with a diameter of 19 mm as the separator, and 1M LiPF6 DEC:EC:EMC=1:1:1Vol% solution was used as the electrolyte and then assembled into a CR2032 button battery in a glove box.

[0029] After the battery was assembled and aged for 12 hours, charge and discharge tests were performed at different potentials. The calcined sample had a discharge capacity of 234.9 mA h g after 150 cycles at a voltage of 3.0-4.8 V and a current density of 1.0 C. -1 After 50 cycles of this process, an EIS test was performed, and the charge transfer impedance was found to be 90.3Ω after fitting.

[0030] Comparative Example 1

[0031] (1) Dissolve 0.005 g of PVDF-HFP and 0.005 g of LiFSI in 100 ml of DMF and fully dissolve and disperse them to obtain solution A;

[0032] (2) adding 3 g of lithium-rich manganese-based material to 100 ml of DMF and stirring and dispersing the mixture under ultrasound to obtain solution B;

[0033] (3) Solution A was added to solution B at a uniform rate within 30 minutes, the solution temperature was controlled at 20°C, and stirring was continued for 3 hours to obtain a mixed solution, which was heated in an oil bath for 5 hours to evaporate all the solvent, and the solid particles were collected and ground. The solid particles were heat-treated in an argon atmosphere, heated to 180°C at a rate of 5°C / min, and kept warm for 5 hours, and naturally cooled to room temperature to obtain a surfactant-coated modified lithium-rich manganese-based positive electrode material.

[0034] The prepared material was mixed with the conductive agent acetylene black (AB) and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. N-methylpyrrolidone (NMP) was used as the solvent and the mixture was stirred in a small beaker at 800 rpm for 2 hours to obtain a slurry. The slurry was coated on the current collector aluminum foil using an automatic coater, placed flat on tempered glass, and dried in a vacuum drying oven at 85°C for 4 hours. The sheets were punched into electrodes with a diameter of 12 mm and dried in a vacuum drying oven at 105°C for 4 hours. The electrodes were then placed in an argon atmosphere in a glove box with a moisture and oxygen content of less than 0.1 ppm for 4 hours to reduce moisture adsorption during transfer. The lithium sheet was cut into a circular piece with a diameter of 19 mm as the negative electrode, the PP separator was cut into a circular piece with a diameter of 19 mm as the separator, and 1M LiPF6 DEC:EC:EMC=1:1:1Vol% solution was used as the electrolyte and then assembled into a CR2032 button battery in a glove box.

[0035] After the battery was assembled and aged for 12 hours, charge and discharge tests were performed at different potentials. The discharge capacity of the calcined sample was 168.75 mA h g after 150 cycles at a voltage of 3.0-4.8 V and a current density of 1.0 C. -1 After 50 cycles of this process, an EIS test was performed, and the charge transfer impedance was found to be 156.1Ω after fitting.

[0036] Comparative Example 2

[0037] (1) 3 g of lithium-rich manganese-based material was added to 100 ml of DMF and fully stirred and dispersed under ultrasound to obtain solution B;

[0038] (2) Solution B was stirred for 3 h, then heated in an oil bath for 5 h to evaporate all the solvent, the solid particles were collected and ground, and the solid particles were heat treated in an argon atmosphere by heating to 180 ° C at a rate of 5 ° C / min and keeping warm for 5 h. The solid particles were naturally cooled to room temperature to obtain a surfactant-coated modified lithium-rich manganese-based positive electrode material.

[0039] The prepared material was mixed with the conductive agent acetylene black (AB) and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. N-methylpyrrolidone (NMP) was used as the solvent and the mixture was stirred in a small beaker at 800 rpm for 2 hours to obtain a slurry. The slurry was coated on the current collector aluminum foil using an automatic coater, placed flat on tempered glass, and dried in a vacuum drying oven at 85°C for 4 hours. The sheets were punched into electrodes with a diameter of 12 mm and dried in a vacuum drying oven at 105°C for 4 hours. The electrodes were then placed in an argon atmosphere in a glove box with a moisture and oxygen content of less than 0.1 ppm for 4 hours to reduce moisture adsorption during transfer. The lithium sheet was cut into a circular piece with a diameter of 19 mm as the negative electrode, the PP separator was cut into a circular piece with a diameter of 19 mm as the separator, and 1M LiPF6 DEC:EC:EMC=1:1:1Vol% solution was used as the electrolyte and then assembled into a CR2032 button battery in a glove box.

[0040] After the battery was assembled and aged for 12 hours, charge and discharge tests were performed at different potentials. The calcined sample had a discharge capacity of 141.1 mA hg after 101 cycles at a voltage of 3.0-4.8 V and a current density of 1.0 C. -1 After 50 cycles of this process, an EIS test was performed, and the charge transfer impedance was found to be 162.5Ω.

[0041] Example 2

[0042] (1) Dissolve 0.05 g of lithium dodecylbenzenesulfonate, 0.005 g of PVDF-HFP, and 0.005 g of LiPF6 in 100 ml of DMF and fully dissolve and disperse them to obtain solution A;

[0043] (2) adding 3 g of lithium-rich manganese-based material to 100 ml of DMF and stirring and dispersing the mixture under ultrasound to obtain solution B;

[0044] (3) Solution A was added to solution B at a uniform rate within 30 minutes, the solution temperature was controlled at 20°C, and stirring was continued for 3 hours to obtain a mixed solution, which was heated in an oil bath for 5 hours to evaporate all the solvent, and the solid particles were collected and ground. The solid particles were heat-treated in an argon atmosphere, heated to 180°C at a rate of 5°C / min, and kept warm for 5 hours, and naturally cooled to room temperature to obtain a surfactant-coated modified lithium-rich manganese-based positive electrode material.

[0045] The prepared material was mixed with the conductive agent acetylene black (AB) and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. N-methylpyrrolidone (NMP) was used as the solvent and the mixture was stirred in a small beaker at 800 rpm for 2 hours to obtain a slurry. The slurry was coated on the current collector aluminum foil using an automatic coater, placed flat on tempered glass, and dried in a vacuum drying oven at 85°C for 4 hours. The sheets were punched into electrodes with a diameter of 12 mm and dried in a vacuum drying oven at 105°C for 4 hours. The electrodes were then placed in an argon atmosphere in a glove box with a moisture and oxygen content of less than 0.1 ppm for 4 hours to reduce moisture adsorption during transfer. The lithium sheet was cut into a circular piece with a diameter of 19 mm as the negative electrode, the PP separator was cut into a circular piece with a diameter of 19 mm as the separator, and 1M LiPF6 DEC:EC:EMC=1:1:1Vol% solution was used as the electrolyte and then assembled into a CR2032 button battery in a glove box.

[0046] After the battery was assembled and aged for 12 hours, charge and discharge tests were performed at different potentials. The discharge capacity of the calcined sample was 232.1 mA hg after 150 cycles at a voltage of 3.0-4.8 V and a current density of 1.0 C. -1 After 50 cycles of this process, an EIS test was performed, and the charge transfer impedance was found to be 91.6Ω after fitting.

[0047] Example 3

[0048] (1) Dissolve 0.05 g of lithium dodecyl sulfate, 0.005 g of PVDF, and 0.005 g of LiFSI in 100 ml of DMF and fully dissolve and disperse them to obtain solution A;

[0049] (2) adding 2 g of lithium-rich manganese-based material to 100 ml of DMF and stirring and dispersing the mixture under ultrasound to obtain solution B;

[0050] (3) Solution A was added to solution B at a uniform rate within 30 minutes, the solution temperature was controlled at 20°C, and stirring was continued for 3 hours to obtain a mixed solution, which was heated in an oil bath for 5 hours to evaporate all the solvent, and the solid particles were collected and ground. The solid particles were heat-treated in an argon atmosphere, heated to 180°C at a rate of 5°C / min, and kept warm for 5 hours, and naturally cooled to room temperature to obtain a surfactant-coated modified lithium-rich manganese-based positive electrode material.

[0051] The prepared material was mixed with the conductive agent acetylene black (AB) and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. N-methylpyrrolidone (NMP) was used as the solvent and the mixture was stirred in a small beaker at 800 rpm for 2 hours to obtain a slurry. The slurry was coated on the current collector aluminum foil using an automatic coater, placed flat on tempered glass, and dried in a vacuum drying oven at 85°C for 4 hours. The sheets were punched into electrodes with a diameter of 12 mm and dried in a vacuum drying oven at 105°C for 4 hours. The electrodes were then placed in an argon atmosphere in a glove box with a moisture and oxygen content of less than 0.1 ppm for 4 hours to reduce moisture adsorption during transfer. The lithium sheet was cut into a circular piece with a diameter of 19 mm as the negative electrode, the PP separator was cut into a circular piece with a diameter of 19 mm as the separator, and 1M LiPF6 DEC:EC:EMC=1:1:1Vol% solution was used as the electrolyte and then assembled into a CR2032 button battery in a glove box.

[0052] After the battery was assembled and aged for 12 hours, charge and discharge tests were performed at different potentials. The discharge capacity of the calcined sample was 230.7 mA h g after 150 cycles at a voltage of 3.0-4.8 V and a current density of 1.0 C. -1 After 50 cycles of this process, an EIS test was performed, and the charge transfer impedance was found to be 95.8Ω after fitting.

[0053] Example 4

[0054] (1) Dissolve 0.07 g of lithium dodecyl sulfate, 0.007 g of PVDF, and 0.007 g of LiFSI in 100 ml of DMF and fully dissolve and disperse them to obtain solution A;

[0055] (2) adding 3 g of lithium-rich manganese-based material to 100 ml of DMF and stirring and dispersing the mixture under ultrasound to obtain solution B;

[0056] (3) Solution A was added to solution B at a uniform rate within 30 minutes, the solution temperature was controlled at 20°C, and stirring was continued for 3 hours to obtain a mixed solution, which was heated in an oil bath for 5 hours to evaporate all the solvent, and the solid particles were collected and ground. The solid particles were heat-treated in an argon atmosphere, heated to 180°C at a rate of 5°C / min, and kept warm for 5 hours, and naturally cooled to room temperature to obtain a surfactant-coated modified lithium-rich manganese-based positive electrode material.

[0057] The prepared material was mixed with the conductive agent acetylene black (AB) and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. N-methylpyrrolidone (NMP) was used as the solvent and the mixture was stirred in a small beaker at 800 rpm for 2 hours to obtain a slurry. The slurry was coated on the current collector aluminum foil using an automatic coater, placed flat on tempered glass, and dried in a vacuum drying oven at 85°C for 4 hours. The sheets were punched into electrodes with a diameter of 12 mm and dried in a vacuum drying oven at 105°C for 4 hours. The electrodes were then placed in an argon atmosphere in a glove box with a moisture and oxygen content of less than 0.1 ppm for 4 hours to reduce moisture adsorption during transfer. The lithium sheet was cut into a circular piece with a diameter of 19 mm as the negative electrode, the PP separator was cut into a circular piece with a diameter of 19 mm as the separator, and 1M LiPF6 DEC:EC:EMC=1:1:1Vol% solution was used as the electrolyte and then assembled into a CR2032 button battery in a glove box.

[0058] After the battery was assembled and aged for 12 hours, charge and discharge tests were performed at different potentials. The discharge capacity of the calcined sample was 229.3 mA hg after 150 cycles at a voltage of 3.0-4.8 V and a current density of 1.0 C. -1 After 50 cycles of this process, an EIS test was performed, and the charge transfer impedance was found to be 96.1Ω after fitting.

[0059] Example 5

[0060] (1) Dissolve 0.05 g of lithium dodecyl sulfate, 0.005 g of PVDF-HFP, and 0.005 g of LiFSI in 100 ml of DMF and fully dissolve and disperse them to obtain solution A;

[0061] (2) adding 3 g of lithium-rich manganese-based material to 100 ml of DMF and stirring and dispersing the mixture under ultrasound to obtain solution B;

[0062] (3) Solution A was added to solution B at a uniform rate within 15 minutes, the solution temperature was controlled at 15°C, and stirring was continued for 4 hours to obtain a mixed solution, which was heated in an oil bath for 5 hours to evaporate all the solvent, and the solid particles were collected and ground. The solid particles were heat-treated in an argon atmosphere, the temperature was increased to 200°C at a rate of 5°C / min, and the temperature was kept for 4 hours, and the mixture was naturally cooled to room temperature to obtain a surfactant-coated modified lithium-rich manganese-based positive electrode material.

[0063] The prepared material was mixed with the conductive agent acetylene black (AB) and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. N-methylpyrrolidone (NMP) was used as the solvent and the mixture was stirred in a small beaker at 800 rpm for 2 hours to obtain a slurry. The slurry was coated on the current collector aluminum foil using an automatic coater, placed flat on tempered glass, and dried in a vacuum drying oven at 85°C for 4 hours. The sheets were punched into electrodes with a diameter of 12 mm and dried in a vacuum drying oven at 105°C for 4 hours. The electrodes were then placed in an argon atmosphere in a glove box with a moisture and oxygen content of less than 0.1 ppm for 4 hours to reduce moisture adsorption during transfer. The lithium sheet was cut into a circular piece with a diameter of 19 mm as the negative electrode, the PP separator was cut into a circular piece with a diameter of 19 mm as the separator, and 1M LiPF6 DEC:EC:EMC=1:1:1Vol% solution was used as the electrolyte and then assembled into a CR2032 button battery in a glove box.

[0064] After the battery was assembled and aged for 12 hours, charge and discharge tests were performed at different potentials. The discharge capacity of the calcined sample was 225.7 mA hg after 150 cycles at a voltage of 3.0-4.8 V and a current density of 1.0 C. -1 After 50 cycles of this process, an EIS test was performed, and the charge transfer impedance was found to be 102.4Ω after fitting.

[0065] The above contents are only basic descriptions of the concept of the present invention, and any equivalent transformations made according to the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a surfactant-coated modified lithium-rich manganese-based positive electrode material, characterized in that: The following steps are involved: (1) dissolving a certain amount of surfactant, polymer, and lithium salt in a solvent and fully dissolving and dispersing them to obtain solution A; (2) adding a certain amount of lithium-rich manganese-based cathode material to a solvent and fully stirring and dispersing the material under ultrasound to obtain solution B; (3) adding solution A to solution B at a uniform rate over a certain period of time, and continuously stirring for a certain period of time to obtain a mixed solution, heating the mixed solution in an oil bath to evaporate all the solvent, collecting and grinding the solid particles, and heat-treating the solid particles under a protective atmosphere to obtain a surfactant-coated modified lithium-rich manganese-based positive electrode material.

2. The method for preparing a surfactant-coated modified lithium-rich manganese-based positive electrode material according to claim 1, characterized in that: The surfactant described in step (1) is at least one of lithium dodecyl sulfate, hexadecyltrimethylammonium bromide, and lithium dodecylbenzenesulfonate, and the surfactant concentration is 0.4-1 g / L.

3. The method for preparing a surfactant-coated modified lithium-rich manganese-based positive electrode material according to claim 1, characterized in that: The polymer described in step (1) is at least one of PVDF, PVDF-HFP, and PVDF-CTFE, and the mass ratio of the surfactant, the polymer, and the lithium salt is 1:0.02-0.10:0.02-0.

10.

4. The method for preparing a surfactant-coated modified lithium-rich manganese-based positive electrode material according to claim 1, characterized in that: The lithium salt described in step (1) is at least one of LiFSI, LiPF6, and LiNO3.

5. The method for preparing a surfactant-coated modified lithium-rich manganese-based positive electrode material according to claim 1, characterized in that: The solvent described in step (1) is at least one of DMF and NMP.

6. The method for preparing a surfactant-coated modified lithium-rich manganese-based positive electrode material according to claim 1, characterized in that: The solvent and its amount in step (2) are the same as those in step (1), and the amount of lithium-rich manganese-based material added is 15-50 g / L.

7. The method for preparing a surfactant-coated modified lithium-rich manganese-based positive electrode material according to claim 1, characterized in that: The time for uniformly adding solution A to solution B in step (3) is 15-45 minutes, the stirring reaction time is 2-4 hours, and the reaction temperature is 15-25°C.

8. The method for preparing a surfactant-coated modified lithium-rich manganese-based positive electrode material according to claim 1, characterized in that: The heating and evaporation time in the oil bath described in step (3) is 4-6 hours.

9. The method for preparing a surfactant-coated modified lithium-rich manganese-based positive electrode material according to claim 1, characterized in that: The solid particles described in step (3) are treated under a protective atmosphere, wherein the protective atmosphere is one of argon and nitrogen, and the temperature is raised to 150-200° C. at 5° C. / min and kept warm for 4-6 hours.

10. The method for preparing a surfactant-coated modified lithium-rich manganese-based positive electrode material according to any one of claims 1 to 9, characterized in that: The coating layer thickness is 20-50nm.

Images