A lithium-rich manganese-based positive electrode material synthesized by a molten salt method, a preparation method and applications thereof

Abstract

The application discloses a lithium-rich manganese-based positive electrode material synthesized by a molten salt method, a preparation method and application, and the lithium-rich manganese-based positive electrode material has a general formula of Li a Mn b Ni c Co d DoE e O2; wherein DoE is a doping element, which can be one element or multiple elements; a:b:c:d:e depend on the molar ratio of Li, Mn, Ni, Co and the doping element in the precursor, a:(b+c+d+e)>1, b+c+d+e=1. The preparation method is that an excess lithium source, a lithium-rich manganese precursor, a molten salt and a substance with a required doping element are uniformly mixed, ultrasonic treatment is carried out at a sintering temperature, and the lithium-rich manganese-based positive electrode material is obtained after cooling. The application is used for preparing a positive electrode active material, is used as a positive electrode sheet in a lithium ion battery, and can effectively improve the electrochemical performance of the battery.

Description

Technical Field

[0001] This invention relates to the field of cathode material preparation technology, and in particular to a lithium-rich manganese-based cathode material synthesized by molten salt method, its preparation method and application. Background Technology

[0002] Lithium-ion batteries are particularly important in modern electrical equipment, holding a crucial strategic position in electric vehicles, portable electronic devices, and energy storage. As downstream demands for power batteries continue to rise, the need for next-generation high-voltage, high-capacity batteries is urgent. Lithium-rich manganese-based cathode active materials, as a core component of next-generation lithium-ion batteries, directly impact their performance.

[0003] In the sintering stage, doping is commonly used to enhance the performance of lithium-rich manganese-based cathode materials. This typically requires heating at high temperatures for several hours to allow the dopant elements to thermally diffuse over a sufficiently long distance, ultimately dispersing the dopant elements within the lithium-rich manganese-based cathode material.

[0004] Currently, the most common approach to lithium-rich manganese-based cathode materials (LRMs) is to mitigate voltage decay, improve charge-discharge specific capacity, and enhance material stability through element doping. To ensure more uniform dispersion of the elements within the material, researchers typically choose to dope the desired chemical substances during the sintering stage, mixing the additives and precursors via mechanical stirring before sintering. This synthesis method often suffers from problems such as uneven distribution of dopant elements, dopant agglomeration, and prolonged sintering time.

[0005] This patent describes a process where ultrasonic waves are applied during sintering to accelerate ion movement when the molten salt has reached a fully molten state, thereby preparing lithium-rich manganese-based cathode materials. This allows the doped elements to be more uniformly dispersed in the cathode material and significantly reduces the high-temperature sintering time, saving energy consumption. Summary of the Invention

[0006] The purpose of this invention is to address the aforementioned problems by providing a lithium-rich manganese-based cathode material synthesized via a molten salt method, its preparation method, and its applications. The preparation method of this invention significantly reduces the heat treatment time at high temperatures, thereby reducing energy consumption. The prepared cathode active material can effectively improve the cycle performance of the battery. When used as a cathode sheet in lithium-ion batteries, this cathode active material can effectively enhance the battery's cycle performance.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: A lithium-rich manganese-based cathode material synthesized by molten salt method, wherein the general formula of lithium-rich manganese-based cathode materials is Li. a Mn b Ni c Co d DoEe O2; where DoE represents the doping element, which can be one element or multiple elements; a:b:c:d:e depends on the lithium source, the molar ratio of Mn, Ni, Co and the doping element in the precursor, a:(b+c+d+e)>1, b+c+d+e=1. The final prepared lithium-rich manganese-based cathode material has the following molar ratio range: Li:Ni:Co:Mn:DoE=1.1-1.4:0.2-0.4:0-0.2:0.6-0.8:0.001-0.04.

[0008] A method for synthesizing lithium-rich manganese-based cathode materials via molten salt method includes the following steps: S1. Mix an excess of lithium source, lithium-rich manganese precursor, molten salt and material containing the desired doping element uniformly; wherein the molten salt accounts for 1 / 2-4 / 5 of the total sintering mass; S2. The powder uniformly mixed in step S1 is heated to the highest sintering temperature of 780℃-1000℃ at a heating rate of 1℃-10℃ / min and held for 20min-60min to make the molten salt completely melted, while the ultrasonic probe is preheated. S3. Lower the preheated ultrasonic probe below the molten liquid surface for ultrasonic treatment; S4. Remove the ultrasonic probe after ultrasonic treatment from the liquid surface, keep the melt at a certain temperature for a period of time, and then perform a cooling operation to obtain a lithium-rich manganese-based cathode material mixed with molten salt. S5. The lithium-rich manganese-based cathode material mixed with molten salt obtained in step S4 is cleaned with deionized water or alcohol and dried to obtain a lithium-rich manganese-based cathode material with element doping.

[0009] The lithium source mentioned in the above technical solution includes, but is not limited to, one or a mixture of at least two of Li₂CO₃, LiOH, or LiCl; the lithium-rich manganese precursor is Ni. x Co y Mn z CO3 or Ni x Co y Mn z The molten salt is a mixture of one or two of (OH)2, wherein x:y:z = 0.2-0.4: 0-0.2: 0.6-0.8; the molten salt includes, but is not limited to, a mixture of one or more molten salts of NaCl and KCl, wherein the molten salt is in a molten state at the sintering temperature; the substance containing the desired doping element includes, but is not limited to, Al2O3, TiO2, MgO, AlCl3, Mg(NO3)2; the particle size of the substance containing the desired doping element is less than 500 nm, and the molar amount of the doping element accounts for 0.1%-4% of the total molar amount of the metal elements.

[0010] In the above technical solution, the molar mass of the excess lithium source should be 1.1-1.4 times the molar mass of the transition metal element.

[0011] In step S1 of the above technical solution, a high-speed mixer is used for mixing. The speed of the high-speed mixer is 700-1400 r / min, the mixing time is 30-60 min, and the mixing temperature is 30-80℃.

[0012] In step S2 of the above technical solution, the maximum sintering temperature is 780-1000℃, and the holding time can be flexibly changed with the sintering temperature. After holding, it is only necessary for the molten salt to be in a completely molten state. Preferably, the holding time is 30 minutes. In step S2, the preheating temperature of the ultrasonic probe is 1-5℃ higher than the maximum sintering temperature.

[0013] The ultrasonic conditions in the above technical solution are: power of 1500-2500W, frequency of 20KHz, amplitude of 14-20um, and time of 15s-5min.

[0014] In step S4 of the above technical solution, the molten liquid is kept at a temperature of 1-7 hours.

[0015] In step S5 of the above technical solution, the molten salt is cleaned using a solution such as water or alcohol; the drying conditions are a drying temperature of 80-150℃ and a drying time of 6-28h.

[0016] Regarding the above technical solution, the present invention also provides an application of the lithium-rich manganese-based cathode material of this application, the steps of which are: S11. Mix lithium-rich manganese-based cathode material, conductive agent, and binder in a certain mass ratio, and add N-methylpyrrolidone to prepare a uniform slurry. S12. Coat the slurry obtained in step S11 onto an aluminum foil to form a positive electrode sheet of a certain thickness, and dry it under vacuum for a certain time. S12. The positive electrode sheet obtained in S12 is combined with lithium sheet and battery electrolyte in a glove box and then pressed and left to stand to produce a 2032 button battery. The conductive agent can be one or more of acetylene black, conductive carbon black, Super-P or Ketjen black; the binder can be one or more of polyvinylidene fluoride, polyacrylic acid, sodium alginate; the coating thickness is 20 micrometers; the battery electrolyte can be a 1 mol / L carbonate electrolyte or a mixture of ethylene carbonate and ethyl methyl carbonate in a volume ratio of 3:7 or a common commercial lithium-ion battery electrolyte.

[0017] Compared with the prior art, the advantages and positive effects of this invention are: The method for synthesizing lithium-rich manganese-based cathode materials using the molten salt process of this invention significantly reduces the heat preservation time at high temperatures, reduces energy consumption, and facilitates the rapid diffusion of dopants over longer distances. The resulting cathode active material effectively improves the cycle performance of the battery. When used as a cathode sheet in lithium-ion batteries, this cathode active material can effectively enhance the battery's cycle performance. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 Here is a scanning electron microscope image of Example 1 of the present invention; Figure 2 Here are scanning electron microscope images of Example 2 of the present invention; Figure 3 Here are scanning electron microscope images of Example 6 of the present invention; Figure 4 This is a scanning electron microscope image of Comparative Example 1; Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art to all other embodiments obtained without creative effort should be included within the protection scope of the present invention.

[0021] Example 1:

[0022] Materials preparation: 1. Lithium source: LiOH·H2O is selected, and the lithium source molar ratio is 1.3.

[0023] 2. Lithium-rich manganese precursor: using Ni 0.2 Co 0.2 Mn 0.6 CO3 serves as a precursor.

[0024] 3. Molten salt: KCl is used.

[0025] 4. Doping elements: Select aluminum source (Al2O3) with a particle size of less than 500nm, and the molar ratio of aluminum to transition metal ions is 0.015:0.985.

[0026] Preparation steps: Step 1: In a high-speed mixer, mix LiOH·H2O and Ni 0.2 Co 0.2 Mn 0.6 CO3, KCl and Al2O3 were mixed at 70℃ for 60 minutes at a speed of 750 r / min to ensure uniform mixing.

[0027] Step 2: Heat the mixed powder to 830℃ and keep it at that temperature for 30 minutes to completely melt the molten salt. Preheat the ultrasonic probe to 835℃.

[0028] Step 3: The ultrasonic probe is lowered below the surface of the molten liquid and ultrasonic treatment is performed for 5 minutes at a power of 1800W, a frequency of 20KHz, and an amplitude of 16um.

[0029] Step 4: Remove the ultrasonically treated probe from the melt and keep it at a warm temperature for 6 hours before allowing it to cool naturally to room temperature.

[0030] Step 5: Wash the obtained material with deionized water, dry it at 120℃ for 12 hours to obtain aluminum-doped lithium-rich manganese-based cathode material Li. 1.3 Mn 0.591 Ni 0.197 Co 0.197 Al 0.015 O2.

[0031] Example 2:

[0032] Materials preparation: 1. Lithium source: Li2CO3 is selected, and the lithium source molar ratio is 1.2.

[0033] 2. Lithium-rich manganese precursor: using Ni 0.17 Co 0.17 Mn 0.66 (OH)2 is used as a precursor.

[0034] 3. Molten salt: Use a mixture of NaCl and KCl in a molar ratio of 3:1.

[0035] 4. Doping elements: Titanium source (TiO2) with a particle size of less than 500nm is selected, and the molar ratio of Ti element to transition metal ion is 0.012:0.988.

[0036] Preparation steps: Step 1: In a high-speed mixer, mix Li2CO3 and Ni 0.17 Co 0.17 Mn 0.66 (OH)2, NaCl, KCl and TiO2 were mixed at 50℃ for 60 minutes at a speed of 800 r / min.

[0037] Step 2: Heat the mixed powder to 880℃ and keep it at that temperature for 60 minutes to ensure that the molten salt is completely melted. Preheat the ultrasonic probe to 885℃.

[0038] Step 3: Treat under ultrasonic conditions for 3.5 minutes, with a power of 2000W, a frequency of 20KHz, and an amplitude of 18um.

[0039] Step 4: Remove the ultrasound probe and keep it warm for 4 hours, then let it cool down naturally.

[0040] Step 5: Clean the mixture with alcohol, and dry it at 100℃ for 20 hours to obtain titanium-doped lithium-rich manganese-based cathode material Li. 1.2 Mn 0.652 N i0.168 Co 0.168 Ti 0.012 O2.

[0041] Example 3:

[0042] Materials preparation: 1. Lithium source: LiCl is selected, and the lithium source molar ratio is 1.4.

[0043] 2. Lithium-rich manganese precursor: using Ni 0.2 Co 0.2 Mn 0.6 CO3 serves as a precursor.

[0044] 3. Molten salt: NaCl is used.

[0045] 4. Doping elements: Magnesium source (MgO) with a particle size of less than 500 nm is selected, and the molar ratio of magnesium to transition metal ions is 0.03:0.97.

[0046] Preparation steps: Step 1: In a high-speed mixer, mix LiCl and Ni... 0.2 Co 0.2 Mn 0.6 CO3, NaCl and MgO were mixed at 60℃ for 60 minutes at a speed of 850 r / min.

[0047] Step 2: Heat the mixed powder to 900℃ and keep it at that temperature for 30 minutes to ensure the molten salt melts. Preheat the ultrasonic probe to 905℃.

[0048] Step 3: Perform ultrasonic treatment on the melt under the following conditions: power 2100W, frequency 20KHz, amplitude 15um, and treatment time 1 minute.

[0049] Step 4: After ultrasonic treatment, remove the ultrasonic probe, keep it warm for 3.5 hours, and then cool it down to room temperature.

[0050] Step 5: Wash with deionized water and dry at 120℃ for 24 hours to obtain magnesium-doped lithium-rich manganese-based cathode material Li. 1.4 Mn 0.582 Ni 0.194 Co 0.194 Mg 0.03 O2.

[0051] Example 4:

[0052] Materials preparation: 1. Lithium source: LiCl is selected, and the molar ratio of lithium source is 1.3.

[0053] 2. Lithium-rich manganese precursor: using Ni 0.2 Co 0.2 Mn 0.6 CO3 serves as a precursor.

[0054] 3. Molten salt: KCl is used.

[0055] 4. Doping elements: Aluminum source (AlCl3) with a particle size of less than 500nm is selected, and the molar ratio of aluminum to transition metal ions is 0.015:0.985.

[0056] Preparation steps: Step 1: In a high-speed mixer, mix LiCl and Ni... 0.2 Co 0.2 Mn 0.6 CO3, NaCl, and AlCl3 were mixed at 60°C for 60 minutes at a rotation speed of 850 r / min.

[0057] Step 2: Heat the mixed powder to 840℃ and keep it at that temperature for 30 minutes to ensure the molten salt melts. Preheat the ultrasonic probe to 845℃.

[0058] Step 3: Perform ultrasonic treatment on the melt under the following conditions: power 2000W, frequency 20KHz, amplitude 16um, and treatment time 2 minutes.

[0059] Step 4: After ultrasonic treatment, remove the ultrasonic probe, keep it warm for 7 hours, and then cool it down to room temperature.

[0060] Step 5: Wash with deionized water and dry at 120℃ for 16 hours to obtain aluminum-doped lithium-rich manganese-based cathode material Li. 1.3 Mn 0.591 Ni 0.197 Co 0.197 Al 0.015 O2.

[0061] Example 5: Materials preparation: 1. Lithium source: LiCl is selected, and the lithium source molar ratio is 1.4.

[0062] 2. Lithium-rich manganese precursor: using Ni 0.2 Co 0.2 Mn 0.6 CO3 serves as a precursor.

[0063] 3. Molten salt: NaCl is used.

[0064] 4. Doping elements: Magnesium source (Mg(NO3)2) with a particle size of less than 500nm is selected, and the molar ratio of magnesium to transition metal ions is 0.03:0.97.

[0065] Preparation steps: Step 1: In a high-speed mixer, mix LiCl and Ni... 0.2 Co 0.2 Mn 0.6 CO3, NaCl and MgO were mixed at 60℃ for 60 minutes at a speed of 850 r / min.

[0066] Step 2: Heat the mixed powder to 900℃ and keep it at that temperature for 30 minutes to ensure the molten salt melts. Preheat the ultrasonic probe to 905℃.

[0067] Step 3: Perform ultrasonic treatment on the melt under the following conditions: power 1900W, frequency 20KHz, amplitude 17um, and treatment time 1.5 minutes.

[0068] Step 4: After ultrasonic treatment, remove the ultrasonic probe, keep it warm for 3 hours, and then cool it down to room temperature.

[0069] Step 5: Wash with deionized water and dry at 120℃ for 24 hours to obtain magnesium-doped lithium-rich manganese-based cathode material Li. 1.4 Mn 0.582 Ni 0.194 Co 0.194 Mg 0.03 O2.

[0070] Example 6: Materials preparation: 1. Lithium source: LiOH·H2O is selected, and the lithium source molar ratio is 1.3.

[0071] 2. Lithium-rich manganese precursor: using Ni 0.2 Co 0.2 Mn 0.6 CO3 serves as a precursor.

[0072] 3. Molten salt: KCl is used.

[0073] 4. Doping elements: Select aluminum source (Al2O3) with a particle size of less than 500nm, and the molar ratio of aluminum to transition metal ions is 0.015:0.985.

[0074] Preparation steps: Step 1: In a high-speed mixer, mix LiOH·H2O and Ni 0.2 Co 0.2 Mn 0.6 CO3 and Al2O3 were mixed at 70℃ for 60 minutes at a speed of 750 r / min to ensure uniform mixing.

[0075] Step 2: Heat the mixed powder to 830℃ and keep it at that temperature for 6 hours, then let it cool naturally to room temperature.

[0076] Step 3: Wash with deionized water and dry at 120℃ for 12 hours to obtain aluminum-doped lithium-rich manganese-based cathode material Li. 1.3 Mn 0.591 Ni 0.197 Co 0.197 Al 0.015 O2.

[0077] Comparative Example 1

[0078] Materials preparation: 1. Lithium source: LiOH·H2O is selected, and the lithium source molar ratio is 1.3.

[0079] 2. Lithium-rich manganese precursor: using Ni 0.2 Co 0.2 Mn 0.6 CO3 serves as a precursor.

[0080] 3. Molten salt: KCl is used.

[0081] 4. Doping elements: Select aluminum source (Al2O3) with a particle size of less than 500nm, and the molar ratio of aluminum to transition metal ions is 0.015:0.985.

[0082] Preparation steps: Step 1: In a high-speed mixer, mix LiOH·H2O and Ni 0.6 Co 0.2 Mn 0.2 CO3 and Al2O3 were mixed at 70℃ for 60 minutes at a speed of 750 r / min to ensure uniform mixing.

[0083] Step 2: Heat the mixed powder to 830℃ and keep it at that temperature for 12 hours, then let it cool naturally to room temperature.

[0084] Step 3: Wash with deionized water and dry at 120℃ for 12 hours to obtain magnesium-doped lithium-rich manganese-based cathode material Li. 1.3 Mn 0.591 Ni 0.197 Co 0.197 Al 0.015 O2.

[0085] The performance of the cathode materials obtained in the above embodiments and comparative examples was tested and compared, and the results are shown in the table below.

[0086] From the comparison in the table above, we can see that: (1) The main difference between Example 6 and Comparative Example 1 in the table is the different holding time in the high-temperature zone. The results show that insufficient holding time in the high-temperature zone will lead to a significant performance degradation. This is mainly because the time is too short, making it difficult for some metal ions to diffuse to the normal sites of the crystal lattice within a limited time, resulting in incomplete reaction and failure to obtain a complete and ordered crystal structure.

[0087] (2) The main difference between Example 1 and Example 6 in the table is whether ultrasonic operation is performed after the molten salt is completely melted. The results show that the electrochemical performance of the cathode material is greatly improved after ultrasonic operation. This is because ultrasonic operation in molten salt is beneficial for metal ions to diffuse rapidly to the vicinity of the desired site over a long distance. After ultrasonic operation, only a short time of heat preservation at high temperature is needed to allow the metal ions to diffuse to the desired site, and finally form a uniform and stable structure.

[0088] (3) The difference between Example 1 and Comparative Example 1 in the table lies in the ultrasonic operation and the shorter holding time, and the longer holding time without ultrasonic operation. The results show that the electrochemical performance of the cathode material after ultrasonic operation is improved compared with that without ultrasonic operation. This is because ultrasonic operation in molten salt can effectively inhibit the agglomeration of additives, so that the agglomerated additives are quickly broken into nanoscale substances under ultrasonic action, and with the help of the superior fluidity of molten salt, they are more uniformly dispersed in the material, thereby improving the electrochemical performance of the cathode material.

[0089] (4) The electrochemical performance of Examples 1-5 in the table shows that high-temperature ultrasonic operation is not limited by the type of additive.

[0090] (5) From Figure 3 It can be seen that when ultrasonic treatment is not performed and the holding time is insufficient, incomplete material formation is the main reason for low capacity and capacity retention. Figure 4 In comparison, it can be seen that in a normal sintering process, when the holding time is sufficient, the material can be formed, but a large number of incompletely dispersed coated particles can be seen on the surface. Figure 1 and Figure 2 It can be seen that the number of incompletely dispersed coated particles on the surface is significantly reduced after ultrasonic treatment. Ultrasonic treatment of the surface of the melt helps to reduce the agglomeration of doped nanoscale materials and enable them to be more uniformly dispersed throughout the material, thereby improving the electrochemical performance of the battery.

[0091] The method of this invention, when the molten salt reaches a completely molten state, accelerates long-distance ion transport through high-temperature ultrasonic operation, significantly shortening the required heat preservation time for material synthesis by at least 5 hours, which helps reduce energy consumption. Simultaneously, ultrasonic operation allows additives to be more uniformly dispersed in the cathode material, which facilitates the broader participation of dopant elements and improves the performance of the cathode material. When dopants are in an agglomerated form, they may reduce the electrochemical performance of the battery or even fail to provide effective modification.

Claims

1. A lithium-rich manganese-based cathode material synthesized by molten salt method, characterized in that: The general formula for lithium-rich manganese-based cathode materials is Li a Mn b Ni c Co d DoE e O2; where DoE is the doping element, which can be one element or multiple elements; a:b:c:d:e depends on the lithium source, the molar ratio of Mn, Ni, Co and the doping element in the precursor, a:(b+c+d+e)>1, b+c+d+e=1.

2. The lithium-rich manganese-based cathode material synthesized by the molten salt method as described in claim 1, wherein Li:Ni:Co:Mn:DoE = 1.1-1.4:0.2-0.4:0-0.2:0.6-0.8:0.001-0.

04.

3. A method for preparing a lithium-rich manganese-based cathode material synthesized by the molten salt method as described in claim 1 or 2, the method comprising the following steps: S1. Mix an excess of lithium source, lithium-rich manganese precursor, molten salt and material containing the desired doping element uniformly; wherein the molten salt accounts for 1 / 2-4 / 5 of the total sintering mass; S2. The powder uniformly mixed in step S1 is heated to the highest sintering temperature of 780℃-1000℃ at a heating rate of 1℃-10℃ / min and held for 20min-60min to make the molten salt completely melted, while the ultrasonic probe is preheated. S3. Lower the preheated ultrasonic probe below the molten liquid surface for ultrasonic treatment; S4. Remove the ultrasonic probe after ultrasonic treatment from the liquid surface, keep the melt at a certain temperature for a period of time, and then perform a cooling operation to obtain a lithium-rich manganese-based cathode material mixed with molten salt. S5. The lithium-rich manganese-based cathode material mixed with molten salt obtained in step S4 is cleaned with deionized water or alcohol and dried to obtain a lithium-rich manganese-based cathode material with element doping.

4. The preparation method according to claim 3, characterized in that, The lithium source includes, but is not limited to, one or a mixture of at least two of Li₂CO₃, LiOH, or LiCl; the lithium-rich manganese precursor is Ni. x Co y Mn z CO3 or Ni x Co y Mn z The molten salt is a mixture of one or two of (OH)2, wherein x:y:z = 0.2-0.4: 0-0.2: 0.6-0.8; the molten salt includes, but is not limited to, a mixture of one or more molten salts of NaCl and KCl, wherein the molten salt is in a molten state at the sintering temperature; the substance containing the desired doping element includes, but is not limited to, Al2O3, TiO2, MgO, AlCl3, Mg(NO3)2; the particle size of the substance containing the desired doping element is less than 500 nm.

5. The preparation method according to claim 3, characterized in that, The molar mass of excess lithium source should be 1.1-1.4 times that of transition metal elements.

6. The preparation method according to claim 3, characterized in that, In step S1, a high-speed mixer is used for mixing. The speed of the high-speed mixer is 700-1400 r / min, the mixing time is 30-60 min, and the mixing temperature is 30-80℃.

7. The preparation method according to claim 3, characterized in that, In step S2, the maximum sintering temperature is 780-1000℃, and the preferred holding time is 30 minutes; the preheating temperature of the ultrasonic probe is 1-5℃ higher than the maximum sintering temperature.

8. The preparation method according to claim 3, characterized in that, The ultrasonic conditions are: power of 1500-2500W, frequency of 20KHz, amplitude of 14-20um, and time of 15s-5min; in step S4, the molten liquid is kept warm for 1h-7h.

9. The preparation method according to claim 3, characterized in that, In step S5, the molten salt is cleaned using a solution such as water or alcohol; the drying conditions are a drying temperature of 80–150°C and a drying time of 6–28 hours.

10. An application of the lithium-rich manganese-based cathode material as described in claim 1 or 2, characterized in that, The steps for this application are: S11. Mix lithium-rich manganese-based cathode material, conductive agent, and binder in a certain mass ratio, and add N-methylpyrrolidone to prepare a uniform slurry. S12. Coat the slurry obtained in step one onto an aluminum foil to form a positive electrode sheet of a certain thickness, and dry it under vacuum for a certain time. S12. The positive electrode obtained in step two is combined with lithium sheet and battery electrolyte in a glove box and processed by pressing and settling to produce a 2032 button battery. The conductive agent can be one or more of acetylene black, conductive carbon black, Super-P or Ketjen black; the binder can be one or more of polyvinylidene fluoride, polyacrylic acid, sodium alginate; the coating thickness is 20 micrometers; the battery electrolyte can be a 1 mol / L carbonate electrolyte or a mixture of ethylene carbonate and ethyl methyl carbonate in a volume ratio of 3:7 or a common commercial lithium-ion battery electrolyte.

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