WO2021218543A1 - Multi-metal composite oxide-coated modified lithium manganate positive electrode material and preparation method therefor - Google Patents

Abstract

A multi-metal composite oxide-coated modified lithium manganate positive electrode material, in which lithium manganate is the substrate, and the surface of the substrate is covered with a Li(M1)β(M2)γO2 cladding layer, wherein 0<β≤1, 0<γ≤0.5, and M1 is at least one of Mn, Co, and Ni; and M2 is at least one of Al, Mg, Zr, Ti, Sr, Y, W, Bi, La, Sd, Ba, Ce, V, Se, Mo, Nb, and B. The preparation method therefor comprises: according to the stoichiometric ratio for preparing the lithium manganate substrate, mixing raw materials, calcining the mixed material at no lower than 900˚C to obtain a calcined product; mixing the calcined product with a compound containing M1 and a compound containing M2, and calcining again to obtain the multi-metal composite oxide-coated modified lithium manganate positive electrode material. The described modified lithium manganate positive electrode material has a long cyclic service life, in particular having outstanding cyclic performance under high temperature conditions, and at the same time also has a high capacity level.

Description

Multi-metal composite oxide coated modified lithium manganate cathode material and preparation method thereof Technical field

The invention belongs to the field of lithium ion battery positive electrode materials, and in particular relates to a multi-metal composite oxide coated modified lithium manganate positive electrode material and a preparation method thereof.

Background technique

Lithium manganate materials have natural low-cost advantages, but they also have the disadvantages of low battery capacity and poor high-temperature cycles. In order to reduce the capacity and cycle performance gap between lithium manganate materials and ternary materials, lithium manganate materials need to be improved in energy density and high-temperature performance. How to ensure that the high-temperature cycle performance of the lithium manganate material can be effectively improved under the premise of high capacity is one of the key difficulties in the prior art.

The performance defects of lithium manganese oxide are mainly caused by two aspects: (1) The transformation of the tetragonal phase to the tetragonal phase caused by the Jiang Taylor effect causes structural instability; (2) The occurrence of Mn ³⁺ _{in LiMn 2} O ₄ Disproportionation reaction: After 2Mn ³⁺ → Mn ⁴⁺ +Mn ²⁺ , Mn ^{2+ is} dissolved in the solution, so that manganese can be reduced at the negative electrode and deposited on the negative electrode. The self-discharge capacity loss caused by the dissolution of manganese accounts for about 20%-30% of the total capacity loss. The contact resistance and membrane resistance caused by the dissolution of manganese increase significantly, which significantly increases the polarization of the battery, and the positive electrode active material Reduction, capacity reduction, structure collapse, high temperature and long cycle, poor storage performance. In order to solve the high temperature performance and reduce the dissolution of Mn, it can be relieved by sintering optimization, doping, coating and other modification methods. Through sintering into large single crystal particles, the crystal structure is stabilized, and a lattice with smaller unit cell parameters is formed, and metal is doped. Element, shorten the chemical bond length between metal element and oxygen element, improve the bond energy, and reduce side reactions in the coating layer. However, conventional modification methods tend to increase the high-temperature cycle performance of lithium manganate, and at the same time easily cause a decrease in battery capacity, or increase the capacity, but cannot improve the cycle performance, especially the high-temperature cycle performance. As mentioned in the Chinese Patent Application No. 201110253754.4, M ₂ O ₃ (II) is used. M is one or more of B, Al, Ga and In. This substance mainly reacts with the electrolyte to reduce Mn. It dissolves to form a discontinuous coating layer, reducing the impedance of the coating layer, reducing the amount of manganese eluted to 40ppm, the discharge capacity reaches 101.2mAh/g, the capacity retention rate is 80% for 500 cycles at room temperature, and at high temperature 55℃ Under the conditions, the 200-time capacity retention rate will drop to less than 80%. Therefore, according to current literature reports, the lithium manganate materials on the market generally cannot have both good capacity and cycle performance, especially the high temperature cycle performance cannot be effectively improved, and its capacity will rapidly decrease under high temperature conditions.

Summary of the invention

The present invention provides a multi-metal composite oxide coated modified lithium manganate positive electrode material and a preparation method thereof. The lithium manganate positive electrode material not only has high capacity, but also has excellent cycle performance, especially cycle performance at high temperature. .

The technical solution proposed by the present invention is:

A multi-metal composite oxide coated modified lithium manganate positive electrode material. The modified lithium manganate positive electrode material is based on lithium manganate, and the surface of the substrate is coated with Li(M ₁ ) _β (M ₂ ) _γ O ₂ coating layer, where 0＜β≤1, 0＜γ≤0.5, M ₁ is at least one of Mn, Co, and Ni; M ₂ is Al, Mg, Zr, Ti, Sr, Y , W, Bi, La, Sd, Ba, Ce, V, Se, Mo, Nb, B at least one. The present invention introduces the modifying element M2 into the coating layer to form a multi-metal composite oxide coating layer, which can improve the stability of the coating layer, reduce the side reaction of the coating layer and the electrolyte, thereby improving the performance of the battery.

For the above-mentioned modified lithium manganate cathode material, preferably, the molecular formula of the matrix is Li _1+x Mn _2-xy M _y O ₄ , where 0≤x≤0.15, 0≤y≤0.1, M is Al, At least one of Mg, Ti, Nb, Co, and B. More preferably, 0.02≤x≤0.15.

In the above-mentioned modified lithium manganate cathode material, preferably, the _{molar ratio of the Mn element in the matrix to the M 1} element in the coating layer is (100:0.01) to (100:5).

As a general inventive concept, the present invention also provides a method for preparing the above-mentioned multi-metal composite oxide coated modified lithium manganate cathode material, which includes the following steps:

(1) Mix the raw materials according to the stoichiometric ratio for preparing the lithium manganate matrix;

(2) calcining the mixed mixture in step (1) at not less than 900°C and cooling to obtain a calcined product;

(3) Crush the first sintered product and _{mix it with the M 1} compound and the M ₂ compound to obtain a secondary mixture;

(4) The secondary mixture is calcined, and then cooled to room temperature after calcining to obtain the modified lithium manganate cathode material.

In the above preparation method, preferably, in step (2), the calcination temperature is 900-1100° C., and the time is 8-20 h.

In the above preparation method, preferably, in step (4), the calcination temperature is 600-800° C., and the time is 8-15 h.

In the above preparation method, preferably, in step (3), the M ₁ compound is _{one or more of M 1} element-containing oxides, oxyhydroxides, hydroxides, and carbonates.

In the above-mentioned preparation method, preferably, in step (3), the M ₂ compound is one of oxides, hydroxides, phosphates, carbonates, oxyhydroxides, fluorides, acids, and alkalis _{containing M 2 elements.} One or more.

In the above preparation method, preferably, in step (1), the raw materials include a manganese source, a lithium source, and M dopants; the manganese source is MnO ₂ , Mn ₂ O ₃ , Mn ₃ O ₄ , MnCO ₃ , Mn ₅ one or more O _8, M dopant is an oxide containing element M, hydroxides, phosphates, carbonates, oxyhydroxides, acids, bases, one or more.

In the above preparation method, preferably, the lithium source is _{one or more of LiCO 3} , LiOH, and LiCl.

Compared with the prior art, the advantages of the present invention are:

(1) In the present invention, by controlling the stoichiometric ratio and calcining at a high temperature above 900°C for a longer period of time, a first-fired product material with sufficient lithium content, small unit cell volume, and complete crystal structure is obtained, and it is not easy to form a crystal lattice during the calcination process. Defects, the obtained crystal structure is relatively complete, which lays the foundation for obtaining long-cycle life materials. Then, add an appropriate amount of M ₁ compound to the first sintering product, and control the second sintering temperature below 800 ℃, so that a part of the matrix lithium is removed, and the removed lithium reacts with M ₁ and M ₂ elements to form Li(M ₁ ) _β (M ₂ ) _γ O ₂ coating layer, which can reduce the doping proportion of monovalent metal cations in the matrix, and further increase the capacity and energy density. At the same time, the effect of M ₁ element on Li(M ₁ ) _β ( M ₂ ) _γ O ₂ plays a role in stabilizing the structure. Li(M ₁ ) _β (M ₂ ) _γ O _{2 is} wrapped on the surface of the lithium manganate body material to prevent the electrolyte from corroding the internal matrix structure and has a better protective effect.

(2) The Mn dissolution amount of the modified lithium manganate product of the present invention is relatively low and can be controlled within 10 ppm. After the button battery electrical performance test, 3.0-4.3V, the first discharge capacity can reach more than 104.5mAh/g; the full battery electrical performance test: 25℃, 1200 cycles capacity retention rate can reach more than 84%; high temperature 55℃, The capacity retention rate of 800 cycles can reach more than 81%.

(3) The modified lithium manganate cathode material of the present invention not only has long cycle life, especially outstanding cycle performance under high temperature conditions, but also has a high capacity level, which can not only exhibit excellent performance in 3C applications In addition, the present invention can significantly improve the high-temperature cycle and storage performance of lithium manganate in a high-capacity system, and has broad application prospects in power battery systems such as EV and PHEV.

Description of the drawings

Figure 1 is an XRD spectrum of lithium manganate synthesized in Example 1 of the present invention.

Figure 2 is a SEM image of the lithium manganate synthesized in Example 1 of the present invention.

Fig. 3 is the first capacity curve of a button battery made of lithium manganate synthesized in Example 1 of the present invention.

4 is a graph showing the cycle attenuation curve of the aluminum shell battery made of lithium manganate synthesized in Example 1 of the present invention at room temperature (25° C.).

Fig. 5 is a high temperature (55°C) cycle attenuation curve diagram of an aluminum shell battery made of lithium manganate synthesized in Example 1 of the present invention.

Detailed ways

In order to facilitate the understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments of the specification, but the protection scope of the present invention is not limited to the following specific embodiments.

Unless otherwise defined, all professional terms used in the following have the same meaning as commonly understood by those skilled in the art. The terminology used herein is only for the purpose of describing specific embodiments, and is not intended to limit the protection scope of the present invention.

Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or can be prepared by existing methods.

Example 1:

A multi-metal composite oxide coated modified lithium manganate cathode material of the present invention is based on Li _1.075 Mn _1.845 Al _0.08 O ₄ , and the surface of the substrate is coated with Li(Mn) _0.83 (Al) _0.027 O ₂ cladding layer.

The preparation method of the modified lithium manganate cathode material of this embodiment includes the following steps:

(1) According to the _{design ratio of Li 1.075} Mn _1.845 Al _0.08 O ₄ , after calculation, add 10 kg of manganese source raw material MnO ₂ , 2.37 kg of battery-grade lithium carbonate, and 371.8 g of dopant aluminum hydroxide into the high-speed mixer. Mix at 500 rpm for 5 minutes, and then at 1500 rpm for 20 minutes. After the mixing is completed, there is no white spot by visual inspection, and the mixture is obtained;

(2) Using a box-type atmosphere furnace, put the mixture obtained in step (1) into a sagger, and put it into the sintering equipment and put it in the sintering equipment. The air flow rate is 1m ³ /h. /kg mixture (per sintered 1kg mixture, air flow rate is 1m ³ /h) setting, heat up to 950°C at a rate of 2.5°C/min, after 15 hours of constant temperature, naturally cool down to room temperature, and out of the furnace;

(3) The sintered mixture in step (2) is paired with a roller, and then crushed with an ACM crushing equipment, and sieved through 300 meshes to remove the on-screen material to obtain a powder not exceeding 12um, which is a sintered product;

(4) According to the design of M ₁ for Mn and M ₂ for Al, the molar ratio of Mn to M1 in the matrix is calculated at a ratio of 100:4.5, 10kg of the first-fired product, corresponding to weigh Mn ₃ O ₄ 443.9g, Al(OH) ₃ 14.6g; Put 10kg of the first sintered product, 443.9g Mn ₃ O ₄ , 14.6g Al(OH) ₃ into the high-speed mixer of the mixing equipment, and mix at low speed 400rpm for 5min, then 1500rpm for 15min to obtain a mixture;

(5) The mixture obtained in step (4) was calcined at 700°C for 10 hours and sieved to obtain the final sample, which is the product of modified lithium manganate coated with polymetallic composite oxide, and sampled and tested for XRD to obtain the compound phase and XRD pattern see picture 1.

The final sample prepared in this example was scanned by an electron microscope scanner. The result is shown in Figure 2. The primary particles are uniform, the tap density is 2.2 g/cm ³ , the tap density is high, and the internal structure of the material is dense.

The modified lithium manganate product synthesized in this example was used as a positive electrode, assembled into a CR2032 button battery, and the first charge and discharge capacity evaluation was performed on it. The positive electrode mixes the materials according to the mass ratio of modified lithium manganate: SP (conductive carbon black): PVDF (binder) = 92.5: 0.5: 0.25, and then uniformly coats it on the aluminum foil, after drying, rolling, After cutting the pieces, a positive electrode sheet is made, and a metal lithium sheet is used for the negative electrode sheet. After assembling and sealing in the glove box, after static activation for 10 hours, it is tested on the Xinwei 5V, 5mA test cabinet. The voltage range is 3.0-4.3V, and the first capacity is tested by charging and discharging at 0.1C. The test results are shown in Figure 3. The first discharge capacity is reached 112.5mAh/g, the first efficiency reaches 98%, the 1C/0.1C ratio reaches 98%, and the rate performance is excellent.

The modified lithium manganate synthesized in this example was used as a positive electrode to assemble a 053048A aluminum shell battery. The positive electrode was modified according to the modified lithium manganate: SP (conductive carbon black): PVDF (binder) = 93.5/3.25/3.25, The negative electrode is prepared according to the ratio of FSN-1 (Shanghai Shanshan artificial graphite): SP (conductive carbon black): CMC: SBR=94.8/1.5/1.7/2.0, and then the positive electrode slurry is evenly coated on On the aluminum foil, the negative electrode slurry is evenly coated on the copper foil. After filming, assembling, liquid injection and formation, the Xinwei test cabinet is used for testing, and the voltage test range is 3.0-4.2V. Test the cycle performance at room temperature 25°C and high temperature 55°C. Figure 4 is a charge-discharge cycle attenuation curve diagram at room temperature 25°C, and the capacity retention rate reaches 84% after 1200 cycles. Figure 5 is a graph of the charge-discharge cycle curve at a high temperature of 55°C, with a capacity retention rate of 81% for 800 cycles.

The modified lithium manganate synthesized in this example was tested for Mn dissolution: the quantitative evaluation method is: after the steel shell of the battery is clean and dry, add 3g of LMO powder to weld the seal; bake in a vacuum box at 80°C for 12 hours, and then inject it into a syringe 5ml of electrolyte, sealed and placed in an oven at 85°C for 18h. Use a syringe to draw out the electrolyte and filter, and use ICP to test the Mn content of the solution. The dissolved amount of modified lithium manganate Mn prepared in this example was 8 ppm.

Comparative example 1:

Compared with the preparation method of the modified lithium manganate cathode material of this comparative example, the only difference is that Al(OH) ₃ is not added in step (4).

Using the same evaluation method as in Example 1, the final product of Comparative Example 1 was tested for Mn dissolution, and the dissolution amount was 40 ppm. The prepared button battery was tested under a voltage range of 3.0-4.3V and a charge and discharge of 0.1C. The first discharge capacity reached 102.6mAh/g, and the first efficiency reached 93%. The prepared aluminum shell battery was tested under the voltage test range of 3.0-4.2V, and the 1C/0.1C ratio reached 92%, the capacity retention rate of 1200 cycles at room temperature was 82%, and the capacity retention rate of 800 cycles at high temperature of 55°C reached 75%.

Comparative example 2:

The preparation method of the modified lithium manganate cathode material of this comparative example, compared with Example 1, the only difference lies in step (4), the specific operation of step (4) is: weigh Mn ₃ O ₄ 443.9g, Al( OH) ₃ 14.6g, Li ₂ CO ₃ 215.1g; Put 10kg of the first sintered product, 443.9g Mn ₃ O ₄ , 14.6g Al(OH) ₃ , Li ₂ CO ₃ 215.1g into the high-speed mixer of the mixing equipment, Mix at low speed at 400 rpm for 5 minutes, and then at 1500 rpm for 15 minutes to obtain a mixture.

Using the same evaluation method as in Example 1, the Mn dissolution test of the final product of Comparative Example 1 showed that the dissolution amount was 55 ppm. The prepared button battery was tested under a voltage range of 3.0-4.3V and a charge and discharge of 0.1C. The first discharge capacity was 102.5mAh/g, and the first efficiency was 91.5%. The prepared aluminum shell battery was tested under the voltage test range of 3.0-4.2V, and the ratio of 1C/0.1C reached 93%, the capacity retention rate of 1200 weeks at normal temperature was 81%, and the capacity retention rate of 800 weeks at high temperature of 55°C was 74%.

Comparative example 3:

The preparation method of the modified lithium manganate cathode material of this comparative example is the same as the preparation method of the first sintered product in Example 1, that is, the method of step (1) to step (3) is the same. The difference is that in the preparation method of this comparative example Using a mixed solution of ethylenediaminetetraacetic acid, lithium acetate dihydrate, magnesium acetate tetrahydrate and manganese acetate tetrahydrate, adjust the pH to 8.0, and then add the first calcined product prepared in step (3), heat and stir until the sol is formed, The dry gel is dried to obtain the dry gel, and then the dry gel is pre-fired at 300° C., ground, and then calcined at a high temperature of 700° C. to obtain the final product of coated lithium manganate.

Using the same evaluation method as in Example 1, the final product of Comparative Example 1 was tested for Mn dissolution, and the dissolution amount was 40 ppm. The prepared button battery was tested under a voltage range of 3.0-4.3V and a charge-discharge of 0.1C. The first discharge capacity reached 101.2mAh/g, and the first efficiency reached 94%. The prepared aluminum shell battery was tested under the voltage test range of 3.0-4.2V, and the 1C/0.1C ratio reached 95%, the capacity retention rate of 1200 weeks at room temperature was 80%, and the capacity retention rate of 800 cycles at high temperature of 55°C was 73%.

Example 2:

A multi-metal composite oxide coated modified lithium manganate cathode material of the present invention is based on Li _1.075 Mn _1.865 Mg _0.06 O ₄ , and the surface of the substrate is coated with Li(Co) _0.55 (Al) _0.03 O ₂ cladding layer.

The preparation method of the modified lithium manganate cathode material of this embodiment includes the following steps:

(1) According to the _{design ratio of Li 1.075} Mn _1.865 Mg _0.06 O ₄ , after calculation, weigh 10 kg of manganese source raw material MnO ₂ , 2.34 kg of battery-grade lithium carbonate, and 142.5 g of dopant magnesium oxide, and add them to the mixing equipment for high-speed mixing In the machine, first mix at 500 rpm for 5 minutes, and then at 1500 rpm for 20 minutes. After the mixing is completed, there is no white spot by visual inspection, and the mixture is obtained;

(2) Heat the mixture after step (1) to 940°C and sinter at a constant temperature for 12 hours;

(3) The material after step (2) is paired with a roller, and then crushed with an ACM crushing equipment, sieved with 300 meshes, and the oversize is removed to obtain a powder with a particle size of no more than 12um, that is, a sintered product;

(4) According to the design of M ₁ for Co and M ₂ for Al, calculated according to the molar ratio of Mn to Co in the matrix of 100:3.0, 10kg of the first sintered product, corresponding to weighing Co ₃ O ₄ 313.2g, Al(OH ) ₃ 16.5g, and weighed 10kg of the first sintered sample 313.2g Co ₃ O ₄ and 16.5g Al(OH) ₃ , put them into the high-speed mixer of the mixing equipment, first mix at low speed 300 rpm for 5 minutes, and then mix at 1000 rpm for 15 minutes. Mixture;

(5) Finally, the resulting mixture was calcined at 750° C. for 10 hours and sieved with 300 meshes to obtain the final sample, which is the modified lithium manganate cathode material.

The related performance of the modified lithium manganate cathode material of this example was tested according to the same method as in Example 1. The final product, Mn dissolution test, the dissolution amount was 35 ppm. The prepared button battery has a voltage range of 3.0-4.3V and a charge-discharge of 0.1C. The first-time discharge capacity reaches 104.5mAh/g, and the first-time efficiency reaches 95%. The prepared aluminum shell battery was tested under the voltage test range of 3.0-4.2V, and the 1C/0.1C ratio reached 98%, the capacity retention rate of 1200 weeks at room temperature was 85%, the high temperature 55°C, and the capacity retention rate of 800 cycles reached 81%.

Example 3:

A multi-metal composite oxide coated modified lithium manganate cathode material of the present invention is based on Li _1.045 Mn _1.915 Ti _0.04 O ₄ , and the surface of the substrate is coated with Li(Ni) _0.73 (Zr) _0.011 O ₂ cladding layer.

The preparation method of the modified lithium manganate cathode material of this embodiment includes the following steps:

(1) According to the _{design ratio of Li 1.045} Mn _1.915 Ti _0.04 O ₄ , after calculating 10kg of manganese source raw material MnO ₂ , it corresponds to 2.26kg of battery-grade lithium carbonate and 187.3g of dopant titanium oxide. In the mixer, first mix at 500 rpm for 5 minutes, and then at 1500 rpm for 20 minutes. After the mixing is completed, there is no white spot by visual inspection, and the mixture is obtained;

(2) The mixture after step (1) is sintered at a constant temperature at 930°C for 12 hours and cooled;

(3) The material after step (2) is paired with a roller, and then crushed with an ACM crushing equipment, sieved with 300 meshes, and the oversize is removed to obtain a powder with a particle size of no more than 12um, that is, a sintered product;

(4) According to the design of M ₁ for Ni and M ₂ for Zr, calculated according to the molar ratio of Mn to Ni in the matrix of 100:4.0, 10kg of the first sintered product, corresponding to weighing Ni(OH) ₂ 485.2g, ZrO ₂ 9.7g, weighed 10kg of the first sintered product, 485.2g Ni(OH) ₂ , 9.7g ZrO ₂ , put them into the high-speed mixer of the mixing equipment, first mix at low speed 500rpm for 5min, and then 1200rpm for 15min to obtain a mixture;

(5) The mixture obtained in step (4) is calcined at 800° C. for 12 hours and sieved with 300 mesh to obtain the final sample, which is the modified lithium manganate cathode material.

The related performance of the modified lithium manganate cathode material of this example was tested according to the same method as in Example 1. The Mn dissolution test of the final product showed that the dissolution amount was 35 ppm. The prepared button battery has a voltage range of 3.0-4.3V and a charge-discharge of 0.1C. The first test capacity and the first discharge capacity reach 105.2mAh/g, and the first time efficiency reaches 95%. The prepared aluminum shell battery was tested under the voltage test range of 3.0-4.2V, and the 1C/0.1C ratio reached 97%, the capacity retention rate of 1200 weeks at room temperature was 85%, the high temperature 55°C, and the capacity retention rate of 800 cycles reached 83%.

Claims (10)

A multi-metal composite oxide coated modified lithium manganate positive electrode material, characterized in that the modified lithium manganate positive electrode material is based on lithium manganate, and the surface of the substrate is coated with Li(M ₁ ) _β (M ₂ ) _γ O ₂ coating layer, where 0＜β≤1, 0＜γ≤0.5, M ₁ is at least one of Mn, Co, and Ni; M ₂ is Al, Mg, Zr, Ti , Sr, Y, W, Bi, La, Sd, Ba, Ce, V, Se, Mo, Nb, B at least one. The modified lithium manganate cathode material according to claim 1, wherein the molecular formula of the matrix is Li _1+x Mn _2-xy M _y O ₄ , wherein 0≤x≤0.15, 0≤y≤ 0.15, M is at least one of Al, Mg, Ti, Nb, Co, and B. The modified lithium manganate cathode material according to claim 2, wherein _{the molar ratio of the Mn element in the matrix to the M 1} element in the coating layer is (100:0.01) to (100:5) . A method for preparing the multi-metal composite oxide-coated modified lithium manganate positive electrode material according to any one of claims 1 to 3, comprising the following steps: (1) Mix the raw materials according to the stoichiometric ratio for preparing the lithium manganate matrix; (2) calcining the mixed mixture in step (1) at not less than 900°C and cooling to obtain a calcined product; (3) Crush the first sintered product and _{mix it with the M 1} compound and the M ₂ compound to obtain a secondary mixture; (4) The secondary mixture is calcined, and then cooled to room temperature after calcining to obtain a multi-metal composite oxide coated modified lithium manganate positive electrode material. The preparation method according to claim 4, wherein in step (2), the calcination temperature is 900-1100°C, and the time is 8-20h. The preparation method according to claim 4, wherein in step (4), the calcination temperature is 600-800°C, and the time is 8-15h. The production method as claimed in claim 4, wherein the step (3), a compound containing M ₁ M ₁ is an element having an oxide, oxyhydroxide, hydroxide, carbonate of one or more kind. The preparation method according to claim 4, characterized in that, in step (3), the M ₂ compound is an oxide, hydroxide, phosphate, carbonate, oxyhydroxide, fluoride _{containing M 2 element} One or more of, acid and alkali. The preparation method according to claim 4, wherein in step (1), the raw materials include a manganese source, a lithium source, and M dopants; the M dopants are oxides and hydroxides containing M elements One or more of phosphate, carbonate, oxyhydroxide, acid and alkali. The preparation method according to claim 9, wherein the manganese source is _{one or more of MnO 2} , Mn ₂ O ₃ , Mn ₃ O ₄ , MnCO ₃ , and Mn ₅ O ₈ , and the lithium source It is _{one or more of LiCO 3} , LiOH, and LiCl.

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