A lithium-rich manganese-based cathode material and its preparation method

Abstract

The present invention belongs to the technical field of lithium-ion batteries, and particularly relates to a modification method for a lithium-rich manganese-based cathode material. A liquid-phase ion exchange reaction is carried out between the lithium-rich manganese-based cathode material and a tellurous acid source in a dissolved state, and then a calcination treatment is carried out in an oxygen-containing atmosphere to obtain a modified lithium-rich manganese-based cathode material; the tellurous acid source is at least one of telluric acid, tellurous acid, and hydrogen telluric acid; the calcination temperature is 350-750 °C. The present invention also relates to the material prepared by the above method and its application in lithium-ion batteries. The method of the present invention, based on the surface modification of the active material with a tellurous acid source and the calcination treatment, can synergistically improve the electrochemical performance of the active material.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and particularly relates to the technical field of modification of lithium-rich manganese-based cathode materials. Background Art

[0002] With the wide application of lithium-ion batteries in fields such as consumer electronics and electric vehicles, people's requirements for their energy density are getting higher and higher. The key to restricting the improvement of the energy density of lithium-ion batteries is the cathode material.

[0003] Currently, commercially available cathode materials, such as lithium iron phosphate, lithium cobaltate, ternary materials, etc., are difficult to meet people's requirements for energy density. Therefore, there is an urgent need to develop high specific energy lithium-ion battery cathode materials. Lithium-rich manganese-based cathode materials have become the next generation of lithium-ion battery cathode materials with the most promising commercial prospects due to their high specific capacity (>250 mAh / g) and energy density (>800 Wh / kg), as well as the advantages of being green and inexpensive.

[0004] However, the high capacity of lithium-rich manganese-based cathode materials comes from irreversible anion oxidation reactions, accompanied by the evolution of oxygen and structural degradation starting from the surface, resulting in a large number of lithium ions being unable to return to the material interior during discharge, leading to a low initial Coulomb efficiency and the inability to exert its high specific capacity advantage. In addition, there is a structural transformation from the layered phase → spinel phase → rock salt phase during the cycling process of the material, with a rapid attenuation of capacity and voltage, seriously hindering its commercial application. In addition, the electrolyte is easily oxidized at high voltages, and there are more adverse side reactions between the cathode active material and the electrolyte at the interface, further accelerating the deterioration of the material.

[0005] In response to this problem, some methods have been provided in the industry, but it is difficult to effectively control the internal structural stress of the existing method materials and difficult to reduce the side reactions of the surface materials. Therefore, there is an urgent need to develop a lithium-rich manganese-based cathode material with high initial efficiency, long cycle stability, and excellent electrochemical performance. Summary of the Invention

[0006] Aiming at the problems existing in the prior art, the first object of the present invention is to provide a telluric acid source modification method for lithium-rich manganese-based cathode materials, aiming to provide a method for modifying lithium-rich manganese-based cathode materials.

[0007] The second object of the present invention is to provide the modified lithium-rich manganese-based cathode material (also referred to as the modified cathode active material in the present invention) prepared by the above modification method and its application in lithium-ion batteries.

[0008] The third object of the present invention is to provide a lithium-ion battery containing the modified lithium-rich manganese-based cathode material, as well as its cathode and cathode material.

[0009] There are few tellurium doping solutions in the industry. The few existing solutions mainly involve adding a Te source during the preparation stages of the precursor and the active material to achieve Te doping. However, this type of preparation idea can only achieve bulk doping of the core, and it is difficult to control the phase of the material synthesis, and the electrochemical performance needs to be improved. To address this technical problem, the present invention provides the following solutions:

[0010] A method for modifying a lithium-rich manganese-based cathode material, which involves performing a liquid-phase ion exchange reaction between the lithium-rich manganese-based cathode material and a tellurous acid source in a dissolved state, and then performing a calcination treatment in an oxygen-containing atmosphere to obtain a modified lithium-rich manganese-based cathode material;

[0011] The tellurous acid source is at least one of telluric acid, tellurous acid, and hydrogen telluric acid;

[0012] The calcination temperature is 350-750°C.

[0013] Regarding the problems existing in the lithium-rich manganese-based cathode material, the present invention innovatively conducts ion exchange between the lithium-rich manganese-based cathode material and the tellurous acid source in a liquid phase system, and combines the control of calcination in an oxygen-containing atmosphere and the calcination temperature. In this way, Te bulk doping from the outside to the inside can be achieved based on the ion exchange method, and a surface coating structure can be in-situ synchronously constructed using the outside-to-inside ion exchange behavior; the modification method described in the present invention can improve the bulk doping effect, reduce doping impurity phases, and in addition, can in-situ construct a coating structure based on the outside-to-inside exchange behavior, which is beneficial to improving the longitudinal electron and ion transport channels. In the present invention, based on the above-mentioned new modification idea, the existing active materials can be effectively modified, and the electrochemical performance of the modified active materials can be significantly improved, especially beneficial to the electrochemical performance of the materials under high voltage.

[0014] In the present invention, the chemical formula of the lithium-rich manganese-based cathode material is xLi2MnO3·(1−x)LiMO2, where M is one or more of the transition metals Ni, Mn, and Co, and 0.3≤x≤0.6. Preferably, the M includes Ni, Mn, and Co. More preferably, the x is 0.4-0.6.

[0015] In the present invention, in the liquid phase system of ion exchange, the solvent for dissolving the tellurous acid source is water or a mixed solvent of water-organic solvent, and the organic solvent is a solvent that can be miscible with water.

[0016] In the present invention, the implementation method of liquid phase exchange is, for example: placing the lithium-rich manganese-based cathode material in a tellurous acid source solution for ion exchange, or placing the tellurous acid source in a slurry in which the lithium-rich manganese-based cathode material is dispersed for ion exchange.

[0017] In the present invention, using the tellurous acid source is the key to achieving the above-mentioned liquid phase ion exchange and synergistically improving its surface phase and structure.

[0018] In the present invention, the weight ratio of the lithium-rich manganese-based cathode material to the telluric acid source can be adjusted according to the preparation requirements, and is preferably 1:0.01 to 0.2; more preferably 1:0.05 to 0.1.

[0019] In the present invention, there are no special requirements for the initial concentration of the telluric acid source in the liquid-phase exchange system and the solid-liquid ratio of the lithium-rich manganese-based cathode material. For example, it can be adjusted as needed. Considering the processing cost, in the solution system of liquid-phase exchange, the addition concentration of the telluric acid source is 0.2 g / L to 2 g / L; the solid-liquid ratio is 1:(2 to 10).

[0020] In the present invention, there is no special requirement for the temperature in the ion exchange stage. For example, it can be 10 to 100 °C.

[0021] In the present invention, after the ion exchange, desolvation treatment is carried out and then subsequent calcination treatment is carried out;

[0022] Preferably, the desolvation treatment includes evaporation-drying treatment or spray drying treatment;

[0023] Preferably, the oxygen-containing atmosphere is an atmosphere containing at least one gas of air and oxygen;

[0024] In the present invention, under the liquid-phase surface modification of the telluric acid source, further combined with the joint control of the calcination temperature, it is possible to further synergistically improve the bulk migration behavior of tellurium from the outside to the inside and utilize this behavior to in-situ modify the surface and bulk, thereby synergistically improving the performance of the material. Preferably, the calcination temperature is 400 to 700 °C, more preferably 550 to 650 °C;

[0025] Preferably, the calcination time is 1 h to 6 h, preferably 2 to 4 h.

[0026] A preferred method for preparing a modified lithium-rich manganese-based cathode material in the present invention comprises the steps of:

[0027] Step 1: Prepare a lithium-rich manganese-based cathode material according to the existing method: For example, the chemical formula of the lithium-rich manganese-based cathode material is xLi2MnO3·(1−x)LiMO2, where M is one or more of the transition metals Ni, Mn, Co, and 0.3 ≤ x ≤ 0.6.

[0028] Step 2: Dissolve the telluric acid source in a solvent and fully disperse it, then add the lithium-rich manganese-based positive electrode material, after sufficient reaction, heat and stir to evaporate to dryness, and vacuum dry to obtain an intermediate product; the acid telluric acid source is at least one of telluric acid, tellurous acid, and hydrotelluric acid. The solvent is water, or a mixed solvent of water-organic solvent; the organic solvent is a solvent miscible with water. The mass ratio of the telluric acid source to the lithium-rich manganese-based positive electrode material is 0.01:1 to 0.1:1. The method of sufficient reaction (ion exchange) is at least one of stirring or ultrasound, and the time is 1h to 8h. Preferably, the heating and stirring adopts an oil bath at a temperature of 70℃ to 100℃. Preferably, the vacuum drying temperature is 70℃ to 120℃, and the drying time is 6h to 12h.

[0029] Step 3: After grinding the intermediate product, heat-treat it in an oxygen-containing atmosphere, and cool it naturally to obtain a modified sample. The heat treatment temperature is 400-700°C, the heat treatment time is 1h-6h, and the heating rate is 2°C / min-10°C / min.

[0030] The present invention also provides a modified lithium-rich manganese-based positive electrode material prepared by the preparation method.

[0031] In the present invention, the preparation method can give the material a special microscopic physical and chemical structure, for example, the modified lithium-rich manganese-based positive electrode material has a synchronously constructed Te-doped active core and a spinel coating shell formed by in-situ synchronous surface transformation. In the present invention, the product prepared by the modification method has excellent electrochemical properties, especially excellent high-voltage electrochemical properties.

[0032] The present invention also provides an application of the modified lithium-rich manganese-based positive electrode material, which is used as a positive electrode active material to prepare a lithium-ion battery;

[0033] In the present invention, the modified active material prepared by the present invention can be used to assemble the required lithium ion battery and its positive electrode and positive electrode material based on the existing method.

[0034] The present invention also provides a positive electrode material for a lithium ion battery, comprising the modified lithium-rich manganese-based positive electrode material;

[0035] Preferably, it further comprises a binder and a conductive agent;

[0036] Preferably, the content of the binder is less than or equal to 15 wt. %; the content of the conductive agent is less than or equal to 15 wt. %.

[0037] The present invention also provides a positive electrode of a lithium ion battery, comprising a current collector and a positive electrode material composited on the surface thereof, characterized in that the positive electrode material comprises the positive electrode material of the modified active material of the present invention.

[0038] The present invention also provides a lithium-ion battery, which includes a positive electrode containing a modified active material.

[0039] Beneficial effects

[0040] 1. The present invention innovatively conducts ion exchange on the lithium-rich manganese-based cathode material and telluric acid source in a liquid phase system, and combines it with calcination treatment in an oxygen-containing atmosphere. In this way, Te bulk doping from the outside to the inside can be achieved based on ion exchange, and a surface coating structure can be in-situ synchronously constructed by utilizing the ion exchange behavior from the outside to the inside. The modification method of the present invention can improve the bulk doping effect, reduce doping impurity phases, and stabilize the lattice framework. In addition, it can in-situ construct a coating structure based on the exchange behavior from the outside to the inside, which is beneficial to improving longitudinal electron and ion transport and reducing adverse side reactions at the surface and interface during charge and discharge. In the present invention, based on the above-mentioned new modification idea, the existing active materials can be effectively modified, and the electrochemical performance of the modified active materials can be significantly improved, especially beneficial to the electrochemical performance of the materials under high voltage.

[0041] 2. The present invention provides a lithium-rich manganese-based cathode material with a Te-doped active core and a surface spinel coating shell. By using a simple telluric acid source treatment, the effects of both coating and doping can be achieved in one step. The method is simple and effective, with low cost, and is suitable for large-scale production. Description of the drawings

[0042] Figure 1 XRD pattern of acid-modified sample 1 in Example 1 of the present invention

[0043] Figure 2 SEM spectrum of acid-modified sample 1 in Example 1 of the present invention

[0044] Figure 3 First charge-discharge curve of the coin-type half-cell of acid-modified sample 1 in Example 1 of the present invention.

[0045] Figure 4 Cycling performance of the coin-type half-cells of acid-modified sample 1 and Comparative Example 1 in Example 1 of the present invention. Detailed implementation manners

[0046] The following examples are used to illustrate the present invention, but do not limit the scope of the present invention. And in the embodiments of the present invention, unless otherwise specified, the means used are all conventional means in the art, and the reagents used can be obtained through conventional commercial channels.

[0047] The technical solutions of the present invention will be further described and illustrated below through specific implementation manners in combination with the drawings.

[0048] In the following examples:

[0049] (1) Battery assembly: The materials prepared in the examples or comparative examples were used as active materials. The active materials were mixed with acetylene black and polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1, and N-methylpyrrolidone (NMP) was added and ground into a slurry. The slurry was coated on aluminum foil with a scraper, dried, and cut into positive electrode sheets; then, in an argon glove box (water < 0.01 ppm, oxygen < 0.01 ppm), a CR2025 type button half-cell was assembled, where the positive electrode was the above-mentioned positive electrode sheet, the counter electrode was a lithium sheet, the separator was Celgard 2500, and the electrolyte was a solution prepared with dimethyl carbonate, diethyl carbonate, and ethyl carbonate in a volume ratio of 1:1:1 as the solvent and 1 mol / L LiPF6 as the solute.

[0050] (2) Battery performance test: A LAND CT2001A tester, purchased from Wuhan Blue Electronic Co., Ltd., was used; at 25 °C, at 0.1C (1C = 250 mA / g), charge and discharge cycles were carried out in the voltage range of 2.0 V to 4.8 V for 3 weeks, and then continued to charge and discharge cycles at 1C in the voltage range of 2.0 V to 4.8 V until 200 weeks.

[0051] In the present invention, the lithium-rich manganese-based positive electrode material can be a commercially available product in the industry or prepared based on existing methods. For example, a hydroxide or carbonate-type precursor of the positive electrode element is prepared in advance, and then compounded with a lithium source and calcined to obtain it.

[0052] Example 1

[0053] (1) Using manganese sulfate, nickel sulfate, and cobalt sulfate as raw materials, the reaction raw materials were weighed according to the molar ratio of Mn:Ni:Co elements of 4:1:1, and deionized water was added to prepare a 2 mol / L metal salt solution.

[0054] (2) The above solution was mixed with a 2 mol / L sodium carbonate solution in a continuous stirred tank reactor under a N2 atmosphere. The temperature was 65 °C and the pH was 10 throughout the process. The precursor suspension was filtered, washed first with deionized water, and then dried at 80 °C for 24 h to obtain the precursor.

[0055] (3) The precursor was mixed with Li2CO3 in a ratio of NCM:Li element molar ratio of 1:1.5, sintered at 500 °C (marked as T1) for 5 h, and then sintered in an air atmosphere at 800 °C (marked as T2) for 12 h to synthesize the lithium-rich manganese-based positive electrode material.

[0056] (4) Disperse 0.06 g of telluric acid (telluric acid source) in 50 ml of deionized water and dissolve it thoroughly by stirring. Then add 2 g of the lithium-rich manganese-based cathode material to the solution. Continue to stir the surface reaction at 25 °C for 3 h, and then stir in an oil bath at 90 °C until the solution is evaporated to dryness. Then continue to dry in a vacuum oven at 80 °C for 8 h to obtain an intermediate product.

[0057] (5) After thoroughly grinding the intermediate product, place it in a porcelain boat and put it in a muffle furnace. Heat-treat it in an air atmosphere for 3 h, the heat-treatment temperature is 600 °C (marked as T3), and the heating rate is 3 °C / min. Then cool it with the furnace to obtain the telluric acid source-modified lithium-rich manganese-based cathode material.

[0058] As Figure 1 shown in the XRD pattern of

[0059] As Figure 2 shown in the SEM image of

[0060] As Figure 3 shown in the first charge-discharge curve of

[0061] As Figure 4 shown in the cycle curve of

[0062] Example 2

[0063] Compared with Example 1, the difference is only that in step 4, the telluric acid source used is tellurous acid, and other operations and parameters are the same as those in Example 1.

[0064] Obtain a coin-type half-cell containing the sample of Example 2 by the same method as in Example 1. Its first-cycle discharge capacity can reach 270.4 mAh / g at a voltage range of 2 - 4.8 V and a current density of 25 mA / g, and the first-cycle Coulombic efficiency is as high as 93.1%.

[0065] The same method as in Example 1 was used to obtain a coin-type half-cell containing the sample of Example 2. When cycled in the voltage range of 2 - 4.8 V and at a current density of 250 mA / g, its discharge specific capacity can reach 235.5 mAh / g, and the capacity retention rate is as high as 74.2% after 200 cycles.

[0066] Example 3

[0067] Compared with Example 1, the difference is only that in Step 4, the mass of telluric acid is 0.1 g, and other operations and parameters are the same as those in Example 1.

[0068] The same method as in Example 1 was used to obtain a coin-type half-cell containing the sample of Example 3. When cycled in the voltage range of 2 - 4.8 V and at a current density of 25 mA / g, its initial discharge capacity can reach 268.8 mAh / g, and the initial Coulombic efficiency is as high as 88.5%.

[0069] The same method as in Example 1 was used to obtain a coin-type half-cell containing the sample of Example 3. When cycled in the voltage range of 2 - 4.8 V and at a current density of 250 mA / g, its discharge specific capacity can reach 233 Ah / g, and the capacity retention rate is as high as 72.1% after 200 cycles.

[0070] Example 4

[0071] Compared with Example 1, the difference is only that in Step 5, the heat treatment time is 1 h, and other operations and parameters are the same as those in Example 1.

[0072] The same method as in Example 1 was used to obtain a coin-type half-cell containing the sample of Example 4. When cycled in the voltage range of 2 - 4.8 V and at a current density of 25 mA / g, its initial discharge capacity can reach 265.5 mAh / g, and the initial Coulombic efficiency is as high as 84.4%.

[0073] The same method as in Example 1 was used to obtain a coin-type half-cell containing the sample of Example 4. When cycled in the voltage range of 2 - 4.8 V and at a current density of 250 mA / g, its discharge specific capacity can reach 223.6 mAh / g, and the capacity retention rate is as high as 70.4% after 200 cycles.

[0074] Example 5

[0075] Compared with Example 1, the difference is only that in Step 5, the heat treatment temperature is 400 °C.

[0076] The same method as in Example 1 was used to obtain a coin-type half-cell containing the sample of Example 5. When cycled in the voltage range of 2 - 4.8 V and at a current density of 25 mA / g, its initial discharge capacity can reach 266.3 mAh / g, and the initial Coulombic efficiency is as high as 85.6%.

[0077] The same method as in Example 1 was used to obtain a coin-type half-cell containing the sample of Example 5. When cycled in the voltage range of 2 - 4.8 V and at a current density of 250 mA / g, the discharge specific capacity can reach 224.9 mAh / g, and the capacity retention rate is as high as 71.7% after 200 cycles.

[0078] Example 6

[0079] Compared with Example 1, the only difference is that in step 5, the heat treatment temperature is 700 °C.

[0080] The same method as in Example 1 was used to obtain a coin-type half-cell containing the sample of Example 6. When cycled in the voltage range of 2 - 4.8 V and at a current density of 25 mA / g, the initial discharge capacity can reach 254.1 mAh / g, and the initial Coulombic efficiency is as high as 83.3%.

[0081] The same method as in Example 1 was used to obtain a coin-type half-cell containing the sample of Example 6. When cycled in the voltage range of 2 - 4.8 V and at a current density of 250 mA / g, the discharge specific capacity can reach 212.5 mAh / g, and the capacity retention rate is as high as 70.6% after 200 cycles.

[0082] Comparative Example 1

[0083] Compared with Example 1, the only difference is that steps 4 - 5 are missing, and the lithium-rich manganese-based cathode material prepared in step 3 is directly assembled electrochemically and measured according to the method of the example. The measurement results are as follows: when cycled in the voltage range of 2 - 4.8 V and at a current density of 25 mA / g, the initial discharge capacity can reach 242.2 mAh / g, and the initial Coulombic efficiency is 74.7%. When cycled in the voltage range of 2 - 4.8 V and at a current density of 250 mA / g, the discharge specific capacity is 199.9 mAh / g, and the capacity retention rate is 54.8% after 200 cycles.

[0084] Comparative Example 2

[0085] Compared with Example 1, the only difference is that telluric acid is not used for surface treatment of the lithium-rich manganese-based cathode material, but telluric acid is directly added during the material preparation process and sintered together. Specifically, in step (3), the precursor, Li2CO3, and telluric acid are mixed together, and then sintered at T1 and T2 to prepare the lithium-rich manganese-based cathode material; and steps 4 - 5 are omitted.

[0086] The same method as in Example 1 was used to obtain a coin-type half-cell of the sample of Comparative Example 2. When cycled in the voltage range of 2 - 4.8 V and at a current density of 25 mA / g, the initial discharge capacity can reach 248.5 mAh / g, and the initial Coulombic efficiency is 77.8%.

[0087] The coin-type half-cell of the sample of Comparative Example 2 was obtained in the same manner as in Example 1. Its discharge specific capacity was 203.2 mAh / g when cycled in the voltage range of 2 - 4.8 V and at a current density of 250 mA / g, and the capacity retention rate was 60.3% after 200 cycles.

[0088] Comparative Example 3

[0089] Compared with Example 1, the difference was only that in Step 4, telluric acid was directly mixed with the lithium-rich manganese-based cathode material by solid-phase mixing. Other operations and parameters were the same as in Example 1.

[0090] The coin-type half-cell of the sample of Comparative Example 3 was obtained in the same manner as in Example 1. Its initial discharge capacity reached 240.3 mAh / g at a current density of 25 mA / g in the voltage range of 2 - 4.8 V, and the initial Coulombic efficiency was 73.5%.

[0091] The coin-type half-cell of the sample of Comparative Example 3 was obtained in the same manner as in Example 1. Its discharge specific capacity was 194.2 mAh / g when cycled in the voltage range of 2 - 4.8 V and at a current density of 250 mA / g, and the capacity retention rate was 55.3% after 200 cycles.

[0092] Comparative Example 4

[0093] Compared with Example 1, the difference was only that in Step 4, sodium tellurate was used to replace the telluric acid, and other operations and parameters were the same as in Example 1.

[0094] The coin-type half-cell of the sample of Comparative Example 4 was obtained in the same manner as in Example 1. Its initial discharge capacity reached 238.2 mAh / g at a current density of 25 mA / g in the voltage range of 2 - 4.8 V, and the initial Coulombic efficiency was 72.6%.

[0095] The coin-type half-cell of the sample of Comparative Example 4 was obtained in the same manner as in Example 1. Its discharge specific capacity was 192.5 mAh / g when cycled in the voltage range of 2 - 4.8 V and at a current density of 250 mA / g, and the capacity retention rate was 51.7% after 200 cycles.

[0096] Comparative Example 5

[0097] Compared with Example 1, the difference was only that in Step 5, the heat treatment temperature (T3) was 800 °C, and other operations and parameters were the same as in Example 1.

[0098] The coin-type half-cell of the sample of Comparative Example 5 was obtained in the same manner as in Example 1. Its initial discharge capacity reached 245.5 mAh / g at a current density of 25 mA / g in the voltage range of 2 - 4.8 V, and the initial Coulombic efficiency was 72.4%.

[0099] The coin-type half-cell of the sample of Comparative Example 5 was obtained in the same manner as in Example 1. Its discharge specific capacity was 193.3 mAh / g when cycled in the voltage range of 2-4.8 V and at a current density of 250 mA / g, and the capacity retention rate was 50.4% after 200 cycles.

[0100] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A modification method for a lithium-rich manganese-based cathode material, characterized in that, A lithium-rich manganese-based cathode material and a telluric acid source in a dissolved state are subjected to a liquid-phase ion-exchange reaction, and then calcined in an oxygen-containing atmosphere to obtain a modified lithium-rich manganese-based cathode material; The telluric acid source is at least one of telluric acid, tellurous acid, and hydrogen telluric acid; The calcination temperature is 350-750 °C; The chemical formula of the lithium-rich manganese-based cathode material is xLi2MnO3·(1−x)LiMO2, where M is one or more of the transition metals Ni, Mn, and Co, and 0.3 ≤ x ≤ 0.6; The weight ratio of the lithium-rich manganese-based cathode material to the telluric acid source is 1:0.01-0.

2.

2. The modification method for a lithium-rich manganese-based cathode material according to claim 1, characterized in that, The weight ratio of the lithium-rich manganese-based cathode material to the telluric acid source is 1:0.05-0.

1.

3. The modification method for a lithium-rich manganese-based cathode material according to claim 1, characterized in that, The solvent for dissolving the telluric acid source is water or a mixed solvent of water-organic solvent, and the organic solvent is a solvent that can be miscible with water.

4. The modification method for a lithium-rich manganese-based cathode material according to claim 1, characterized in that, After ion exchange, desolvation treatment is carried out and then subsequent calcination treatment is carried out.

5. The modification method for a lithium-rich manganese-based cathode material according to claim 4, characterized in that, The desolvation treatment includes evaporation-drying treatment or spray-drying treatment.

6. The modification method for a lithium-rich manganese-based cathode material according to claim 1, characterized in that, The oxygen-containing atmosphere is an atmosphere containing at least one gas of air and oxygen.

7. The modification method for a lithium-rich manganese-based cathode material according to claim 1, characterized in that, The calcination temperature is 400 °C to 700 °C.

8. The modification method for a lithium-rich manganese-based cathode material according to claim 7, characterized in that, The calcination temperature is 550 °C to 650 °C.

9. The modification method for a lithium-rich manganese-based cathode material according to claim 1, characterized in that, The calcination time is 1 h to 6 h.

10. A modified lithium-rich manganese-based cathode material prepared by the modification method according to any one of claims 1 to 9.

11. The modified lithium-rich manganese-based cathode material prepared by the modification method according to claim 10, characterized in that, The modified lithium-rich manganese-based cathode material has a Te-doped active core constructed synchronously and a spinel coating shell formed by in-situ synchronous surface transformation.

12. An application of the modified lithium-rich manganese-based cathode material according to any one of claims 10 to 11, characterized in that, Using it as a cathode active material for preparing a lithium-ion battery.

13. The application of the modified lithium-rich manganese-based cathode material according to claim 12, characterized in that, Using it as a cathode active material for use in preparing the cathode of a lithium-ion battery.

14. A cathode material for a lithium-ion battery, characterized in that, It includes the modified lithium-rich manganese-based cathode material according to any one of claims 10-11.

15. The cathode material for a lithium-ion battery according to claim 14, characterized in that, It also includes a binder and a conductive agent.

16. The cathode material for a lithium-ion battery according to claim 15, characterized in that, The content of the binder is less than or equal to 15 wt.%; the content of the conductive agent is less than or equal to 15 wt.%.

17. A positive electrode of a lithium-ion battery, comprising a current collector and a positive electrode material compounded on its surface, characterized in that, The cathode material includes the cathode material according to any one of claims 14-16.

18. A lithium-ion battery, characterized in that, It includes the cathode according to claim 17.

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