Coating Material and Its Preparation Method, Modified Lithium-Rich Manganese-Based Cathode Material and Its Preparation Method, Battery

Abstract

The present invention belongs to the technical field of battery materials, and discloses a coating material and a preparation method thereof. The coating material X is synthesized by a process of liquid-phase in-situ synthesis and high-temperature sintering-reduction sintering a Y b / YO x , wherein X is at least one of Zn, Cu, and Ni, and Y is at least one of Co, Fe, and Mn. In addition, the present invention discloses a lithium-rich manganese-based cathode material coated and modified with the above coating material. The coating material of the present invention is coated on the surface of the lithium-rich manganese-based cathode material to obtain a modified lithium-rich manganese-based cathode material, which can effectively inhibit the corrosion of the electrolyte, improve the structural stability of the matrix material, and has high rate performance and reversibility.

Description

Technical Field

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

[0002] In the research of battery cathode materials, researchers usually modify the cathode materials through ion doping, surface coating or morphology design. Surface coating can not only inhibit the side reaction between the electrolyte and the electrode, but also effectively inhibit the irreversible phase transition, which is favored by researchers. In addition, researchers also combine modification methods, such as the combination of ion doping and surface coating. CN113839013A discloses a coated and doped nickel-cobalt-manganese ternary material, which is obtained by first co-doping and modifying a nickel-cobalt-manganese ternary material precursor with a rubidium-containing compound and a tungsten-containing compound, and then performing metal oxide coating modification. It can not only reduce the contact between the electrolyte and the electrode material, but also promote the diffusion of lithium ions on the particle surface, and can also improve the capacity retention performance, cycling performance and rate performance of the material.

[0003] Lithium-rich manganese-based cathode materials have a high specific capacity and working voltage, and are one of the choices for lithium-ion battery cathode materials. However, during the electrochemical reaction process of lithium-rich manganese-based cathode materials, lithium ions are removed to form Li vacancies, and at the same time oxygen is precipitated to form oxygen vacancies, which directly weakens the metal-O bonds in the main structure, causing transition metal ions to migrate to the lithium layer, resulting in cation disorder distribution in the surface region of the material, leading to the formation of irreversible crystal phases and rapid voltage decay. The research on the modification of lithium-rich manganese-based cathode materials has always been one of the key directions in this field. When using coating to modify lithium-rich manganese-based cathode materials, the development of coating materials has always been the focus. Summary of the Invention

[0004] The first object of the present invention is to provide a coating material and a preparation method thereof.

[0005] The second object of the present invention is to provide a modified lithium-rich manganese-based cathode material and a preparation method thereof.

[0006] The third object of the present invention is to provide a battery.

[0007] To achieve the above objects, the present invention provides the following specific technical solutions.

[0008] First of all, the present invention provides a coating material, and the chemical general formula of the coating material is X a Y b / YO x ; wherein, X is at least one of Zn, Cu, Ni, Y is at least one of Co, Fe, Mn, 1≤a≤5, 1≤b≤7, 1≤x<1.5.

[0009] In a further preferred embodiment, the coating material is a nanomaterial.

[0010] Secondly, the present invention provides a method for preparing the above coating material, comprising the following steps:

[0011] Adding an ammonia water solution to the metal salt solution of Y to carry out the first co-precipitation reaction, and then adding the metal salt solution of X to carry out the second co-precipitation reaction;

[0012] After the second co-precipitation reaction is completed, separating the solid-liquid of the obtained slurry, washing and drying the solid phase;

[0013] Carrying out the first high-temperature sintering on the dried solid phase, and then carrying out the second reduction sintering to obtain X a Y b / YO x 。

[0014] In a further preferred embodiment, the metal salt of Y is at least one of nitrate and acetate; the metal salt of X is at least one of nitrate and acetate.

[0015] In a further preferred embodiment, the molar ratio of Y in the metal salt of Y to ammonia water during the first co-precipitation reaction is 1:2.2 - 3; the time of the first co-precipitation reaction is 2 - 8 h.

[0016] In a further preferred embodiment, the molar ratio of X in the metal salt of X to ammonia water during the second co-precipitation reaction is 1:2 - 3; the time of the second co-precipitation reaction is 1 - 6 h.

[0017] In a further preferred embodiment, the molar ratio of Y in the metal salt of Y to X in the metal salt of X is 1:0.05 - 0.1.

[0018] In a further preferred embodiment, the temperature of the first high-temperature sintering is 800 - 1100 °C; the time of the first high-temperature sintering is 4 - 20 h.

[0019] In a further preferred embodiment, the atmosphere of the second reduction sintering is a hydrogen atmosphere; the temperature of the second reduction sintering is 500 - 800 °C; the time of the second reduction sintering is 1 - 8 h.

[0020] Based on the same inventive concept, the present invention provides a modified lithium-rich manganese-based cathode material, comprising a lithium-rich manganese-based cathode material matrix and a coating layer located on at least part of the surface of the matrix; the chemical general formula of the coating layer is X a Y b / YO x; wherein, X is at least one of Zn, Cu, and Ni, Y is at least one of Co, Fe, and Mn, 1 ≤ a ≤ 5, 1 ≤ b ≤ 7, 1 ≤ x < 1.5.

[0021] In a further preferred embodiment, the chemical general formula of the lithium-rich manganese-based cathode material matrix is Li 1+m Mn 1-m- n Y n O2, 0.1 ≤ m ≤ 0.5, 0 ≤ n ≤ 0.5.

[0022] The present invention provides a method for preparing a modified lithium-rich manganese-based cathode material, comprising the following steps:

[0023] Disperse the lithium-rich manganese-based cathode material matrix and the aforementioned coating material in ethanol, ball mill, and dry to obtain the modified lithium-rich manganese-based cathode material.

[0024] In a further preferred embodiment, the chemical general formula of the lithium-rich manganese-based cathode material matrix is Li 1+m Mn 1-m- n Y n O2, 0.1 ≤ m ≤ 0.5, 0 ≤ n ≤ 0.5, and Y is one or more of Co, Fe, and Mn.

[0025] In a further preferred embodiment, the mass ratio of the lithium-rich manganese-based cathode material to the aforementioned coating material is 1:0.03 - 0.08.

[0026] In a further preferred embodiment, the ball milling time is 0.5 - 5 h.

[0027] In addition, the present invention provides a battery comprising the above-mentioned modified lithium-rich manganese-based cathode material.

[0028] Compared with the prior art, one or more of the above technical solutions of the present invention can achieve at least one of the following beneficial effects:

[0029] The present invention provides a novel coating material, which is X a Y b / YO x , belonging to a bimetallic site-anchored metal oxide.

[0030] The present invention synthesizes the coating material through a process of liquid-phase in-situ synthesis and high-temperature sintering-reduction sintering. The process is simple, the raw materials are easily available, and large-scale industrial production can be realized.

[0031] The coating material of the present invention is coated on the surface of the lithium-rich manganese-based cathode material to obtain a modified lithium-rich manganese-based cathode material. The modified lithium-rich manganese-based cathode material can effectively inhibit the corrosion of the electrolyte, improve the structural stability of the host material, and has a high reversible capacity and cycle reversibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is the HRTEM image of the Ni2Co3 / CoO nanomaterial prepared in Example 1.

[0033] Figure 2 It is the SEM image of the modified lithium-rich manganese-based cathode material prepared in Example 1.

[0034] Figure 3 For the lithium-rich manganese-based cathode material Li 1.2 Mn 0.58 Co 0.22 The HRTEM image of O2.

[0035] Figure 4 It is the HRTEM image of the modified lithium-rich manganese-based cathode material prepared in Example 1.

[0036] Figure 5 It is the cycle performance graph of the battery.

[0037] Figure 6 It is the rate performance graph of the battery.

[0038] Figure 7 For Li after 100 cycles 1.2 Mn 0.58 Co 0.22 The HRTEM image of O2.

[0039] Figure 8 It is the HRTEM image of the modified lithium-rich manganese-based cathode material prepared in Example 1 after 100 cycles. DETAILED DESCRIPTION OF THE INVENTION

[0040] To further improve the electrochemical performance of the lithium-rich manganese-based cathode material, solve the problems of poor structural stability, poor ion diffusion rate, migration and reduction of transition metals in the crystal structure caused by the easy corrosion of the surface layer of the lithium-rich manganese-based cathode material during charge and discharge, and improve the structural stability and ion diffusion rate of the material, the present invention conducts research from the perspective of coating. First, a coating material and its preparation method are provided, and then a modified lithium-rich manganese-based cathode material and its preparation method are provided.

[0041] The chemical general formula of the coating material provided in some embodiments of the present invention is X a Y b / YO x; wherein, X is at least one of Zn, Cu, and Ni, Y is at least one of Co, Fe, and Mn, 1 ≤ a ≤ 5, 1 ≤ b ≤ 7, and 1 ≤ x < 1.5.

[0042] Preferably, the coating material is a nanomaterial.

[0043] Theoretically analyzed: The X provided by the present invention a Y b / YO x belongs to monodisperse bimetallic site-anchored metal oxides, has a uniform single-atom distribution, and has uniformly dispersed active sites, providing abundant sites for adsorbing surface irreversible reactants and promoting redox reactions. Compared with single-metal sites, bimetallic sites have a specific and stable metal bond structure configuration and exhibit more excellent electrochemical reaction activity.

[0044] Secondly, some embodiments of the present invention provide a preparation method of the above coating material, including the following steps:

[0045] Add an ammonia water solution to the metal salt solution of Y for the first co-precipitation reaction, and then add the metal salt solution of X for the second co-precipitation reaction;

[0046] After the second co-precipitation reaction ends, perform solid-liquid separation on the obtained slurry, wash and dry the solid phase;

[0047] Perform the first high-temperature sintering on the dried solid phase, and then perform the second reduction sintering to obtain X a Y b / YO x .

[0048] Through two co-precipitation reactions and high-temperature sintering, a nanomaterial that can be expressed as XO z -Y2O3 is obtained. Further through reduction sintering, the oxygen in the XO z -Y2O3 nanomaterial structure is removed. Due to the valence diversity of the Y metal, the main material forms a stable structure and has reducible and oxidizable YO x , XO z After deoxygenation, the weaker X-O bond breaks and gradually forms a new X-Y metal bond, and finally, monodisperse bimetallic site X a Y b / YO x is successfully synthesized.

[0049] Those skilled in the art should be aware that based on the principle of the above preparation method, soluble metal salts of Y and X should both be able to achieve the preparation purpose and can be selected according to the actual situation. In some preferred embodiments of the present invention, the metal salt of Y is at least one of nitrate and acetate; the metal salt of X is at least one of nitrate and acetate.

[0050] After determining the basic technical concept, the amounts of various materials in the coprecipitation reaction process can be determined and selected through multiple experiments. After multiple experiments and adjustments by the inventor, in some preferred embodiments of the present invention, the molar ratio of Y in the metal salt of Y to ammonia water in the first coprecipitation reaction process is 1:2.2 - 3; the time of the first coprecipitation reaction is 2 - 8 h. The molar ratio of X in the metal salt of X to ammonia water in the second coprecipitation reaction process is 1:2 - 3; the time of the second coprecipitation reaction is 1 - 6 h.

[0051] In some preferred embodiments of the present invention, the molar ratio of Y in the metal salt of Y to X in the metal salt of X is 1:0.05 - 0.1. If the metal salt of X is too little, then the generated X a Y b / YO x has too few X a Y b bimetallic sites, resulting in fewer reactive sites therein. If the metal salt of X is too much, it is easy to form the double oxide XO y / YO x , thus reducing the proportion of monodisperse bimetallic sites and also affecting the final composite effect.

[0052] In some preferred embodiments of the present invention, the temperature of the first high-temperature sintering is 800 - 1100 °C, for example, it can be 800 °C, 900 °C, 980 °C, 1000 °C, 1100 °C, etc. During the actual sintering process, the sintering time is adjusted adaptively. In some preferred examples of the present invention, the time of the first high-temperature sintering is 4 - 20 h, for example, it can be 4 h, 6 h, 8 h, 10 h, 15 h, 20 h, etc.

[0053] In some preferred embodiments of the present invention, the atmosphere of the second reduction sintering is a hydrogen atmosphere; the temperature of the second reduction sintering is 500 - 800 °C, for example, it can be 500 °C, 600 °C, 700 °C, 800 °C, etc.; the time of the second reduction sintering is 1 - 8 h, for example, it can be 1 h, 2 h, 4 h, 6 h, 8 h, etc.

[0054] In addition, some embodiments of the present invention provide a modified lithium-rich manganese-based cathode material, including a lithium-rich manganese-based cathode material matrix and a coating layer located on at least part of the surface of the matrix; the chemical general formula of the coating layer is X a Y b / YO x ; wherein, X is at least one of Zn, Cu, and Ni, Y is at least one of Co, Fe, and Mn, 1 ≤ a ≤ 5, 1 ≤ b ≤ 7, 1 ≤ x < 1.5.

[0055] The metal single atoms in the coating material can form strong metal-O bonds with oxygen in the host material, effectively avoiding the migration of transition metals on the surface of the electrochemical host material. The abundant active sites of the surface coating material provide a large number of transmission channels for ions and electrons, promoting the rapid transmission of ions and electrons. At the same time, after coating, the cathode material can effectively inhibit the corrosion of the electrolyte.

[0056] The original intention of the present invention is to modify the lithium-rich manganese-based cathode material. In some preferred embodiments of the present invention, the chemical general formula of the lithium-rich manganese-based cathode material matrix is Li 1+m Mn 1-m-n Y n O2, 0.1 ≤ m ≤ 0.5, 0 ≤ n ≤ 0.5.

[0057] Some embodiments of the present invention also provide a preparation method of the modified lithium-rich manganese-based cathode material, including the following steps:

[0058] Disperse the lithium-rich manganese-based cathode material matrix and the aforementioned coating material in ethanol, ball mill, and dry to obtain the modified lithium-rich manganese-based cathode material.

[0059] In some preferred embodiments of the present invention, the chemical general formula of the lithium-rich manganese-based cathode material is Li 1+ m Mn 1-m-n Y n O2, 0.1 ≤ m ≤ 0.5, 0 ≤ n ≤ 0.5, and Y is one or more of Co, Fe, and Mn.

[0060] Generally speaking, for different situations, the amount of the coating can be adjusted. In some preferred embodiments of the present invention, the mass ratio of the lithium-rich manganese-based cathode material matrix to the aforementioned coating material is 1:0.03 - 0.08.

[0061] In some preferred embodiments of the present invention, the ball milling time is 0.5 - 5 h.

[0062] Based on the same inventive concept, some embodiments of the present invention provide a battery, including the above-mentioned modified lithium-rich manganese-based cathode material.

[0063] To facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings of the specification and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0064] Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.

[0065] Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment, etc. used in the present invention can be obtained through market purchase or can be prepared by existing methods.

[0066] Example 1

[0067] (1) Slowly add 500 mL of cobalt nitrate solution with a concentration of 1 mol / L to 80 mL of ammonia water solution with a concentration of 15 mol / L for coprecipitation reaction for 6 h. Then, continue to add 0.025 mol of nickel nitrate and 3.33 mL of ammonia water solution with a concentration of 15 mol / L for secondary coprecipitation reaction for 1 h. After the reaction is completed, the reaction slurry is centrifuged, washed, and dried, and then transferred to a muffle furnace for high-temperature sintering at 980 °C for 10 h to obtain NiO-Co2O3 nanomaterials. The NiO-Co2O3 nanomaterials are ball-milled and then placed in a tube furnace for high-temperature sintering at 800 °C for 1 h in a hydrogen atmosphere to obtain monodisperse bimetallic site Ni2Co3 / CoO nanomaterials.

[0068] Figure 1 Fig. is the HRTEM of Ni2Co3 / CoO nanomaterials. It can be seen that the materials are monodisperse at the nanoscale. After measurement, the bimetallic alloy Ni2Co3 phase is within the red circle, and the CoO phase is within the blue circle.

[0069] (2) Disperse 10 g of lithium-rich manganese-based cathode material Li 1.2 Mn 0.58 Co 0.22 O2 in ethanol, add 0.7 g of the monodisperse bimetallic site Ni2Co3 / CoO nanomaterials obtained in step (1), ball-mill and mix for 4 h, and dry to finally obtain the monodisperse bimetallic site-coated and modified Ni2Co3 / CoO@Li 1.2 Mn 0.58 Co 0.22 O2 lithium-rich manganese-based cathode material.

[0070] Figure 2 Fig. is the SEM image of the finally obtained modified lithium-rich manganese-based cathode material. It can be seen that the materials are in the shape of micron-sized blocks, the particle size distribution is uniform, and there is no particle crushing phenomenon.

[0071] Further analyze the HRTEM images of the lithium-rich manganese-based cathode material before and after coating, and the results are as follows Figure 3 and Figure 4 shown. The surface of the material before coating ( Figure 3 ) is smooth, there is no impurity phase on the surface, and the overall structure is uniform. Figure 4 It shows that a 3-5 nm transparent coating layer covers the surface of the coated material, and the coating layer is uniform.

[0072] Comparative Example 1

[0073] (1) Slowly add 500 mL of cobalt nitrate solution with a concentration of 1 mol / L to 80 mL of ammonia water with a concentration of 15 mol / L for coprecipitation reaction for 8 h. After the reaction slurry is centrifuged, washed, and dried, it is transferred to a muffle furnace and sintered at 980 °C for 10 h to obtain Co2O3 nanomaterials.

[0074] (2) Disperse 10 g of lithium-rich manganese-based cathode material Li 1.2 Mn 0.58 Co 0.22 O2 in ethanol, add 0.7 g of the Co2O3 particles prepared in step (1), ball-mill and mix for 4 h, and dry to finally obtain Co2O3@Li 1.2 Mn 0.58 Co 0.22 O2 lithium-rich manganese-based cathode material.

[0075] Comparative Example 2

[0076] (1) Slowly add 500 mL of cobalt nitrate solution with a concentration of 1 mol / L to 80 mL of ammonia water with a concentration of 15 mol / L for coprecipitation reaction for 8 h. Then add 0.025 mol of nickel nitrate and 0.04 mol of EDTA, and stir at room temperature for 4 h. After the reaction slurry is centrifuged, washed, and dried, it is transferred to a tube furnace and sintered at 800 °C for 1 h in an argon atmosphere to obtain Ni atomic dots / Co2O3.

[0077] (2) Disperse 10 g of lithium-rich manganese-based cathode material Li 1.2 Mn 0.58 Co 0.22 O2 in ethanol, add 0.7 g of Ni atomic dots / Co2O3 in step (1), ball-mill and mix for 4 h, and dry to finally obtain Ni atomic dots / Co2O3@Li 1.2 Mn 0.58 Co 0.22 O2 lithium-rich manganese-based cathode material.

[0078] Example 2

[0079] (1) Slowly add 250 mL of manganese acetate solution with a concentration of 2 mol / L to 100 mL of ammonia water solution with a concentration of 15 mol / L for a coprecipitation reaction for 8 h. Then, continue to add 0.05 mol of copper nitrate and 6.67 mL of ammonia water solution with a concentration of 15 mol / L for a secondary coprecipitation reaction for 6 h. After the reaction slurry is centrifuged, washed, and dried, it is transferred to a muffle furnace and sintered at a high temperature of 1100 °C for 4 h to obtain the CuO-Mn2O3 material. Ball-mill the CuO-Mn2O3 material, and then place it in a tube furnace again and sinter it at a high temperature of 500 °C in a hydrogen atmosphere for 8 h to obtain the monodisperse bimetallic site Cu3Mn7 / MnO nanomaterial.

[0080] (2) Disperse 10 g of the lithium-rich manganese-based cathode material Li 1.2 Mn 0.8 O2 in ethanol, add 0.3 g of the monodisperse bimetallic site Cu3Mn7 / MnO nanomaterial in step (1), ball-mill and mix for 5 h, and dry to finally obtain the monodisperse bimetallic site Cu3Mn7 / MnO@Li 1.2 Mn 0.8 O2 lithium-rich manganese-based cathode material.

[0081] Example 3

[0082] (1) Slowly add 500 mL of ferrous acetate solution with a concentration of 1 mol / L to 73.3 mL of ammonia water solution with a concentration of 15 mol / L for a coprecipitation reaction for 6 h. Then, continue to add 0.04 mol of nickel nitrate and 8 mL of ammonia water solution with a concentration of 15 mol / L for a secondary coprecipitation reaction for 4 h. After the reaction slurry is centrifuged, washed, and dried, it is transferred to a muffle furnace and sintered at a high temperature of 900 °C for 15 h to obtain the NiO-Fe2O3 material. Ball-mill the NiO-Fe2O3 material, and then place it in a tube furnace again and sinter it at a high temperature of 600 °C in a hydrogen atmosphere for 6 h to obtain the monodisperse bimetallic site Ni3Fe5 / FeO 1.15 nanomaterial.

[0083] (2) Disperse 10 g of the lithium-rich manganese-based cathode material Li 1.5 Mn 0.37 Fe 0.13 O2 in ethanol, add 0.4 g of the monodisperse bimetallic site Ni3Fe5 / FeO 1.15 nanomaterial, ball-mill and mix for 4 h, and dry to finally obtain the monodisperse bimetallic site Ni3Fe5 / FeO 1.15 @Li 1.5 Mn 0.37 Fe 0.13 O2 lithium-rich manganese-based cathode material.

[0084] Example 4

[0085] (1) Slowly add 500 mL of cobalt acetate solution with a concentration of 1 mol / L to 100 mL of ammonia water solution with a concentration of 15 mol / L for coprecipitation reaction for 2 h. Then continue to add 0.04 mol of zinc nitrate and 6.67 mL of ammonia water solution with a concentration of 15 mol / L for secondary coprecipitation reaction for 6 h. After the reaction slurry is centrifuged, washed, and dried, it is transferred to a muffle furnace and sintered at 800 °C for 20 h to obtain ZnO-Co2O3 material. The ZnO-Co2O3 material is ball-milled and then placed in a tube furnace again. After sintering at 650 °C for 4 h under a hydrogen atmosphere, monodisperse bimetallic site Zn2Co7 / CoO nanomaterial is obtained.

[0086] (2) Disperse 10 g of lithium-rich manganese-based cathode material Li 1.3 Mn 0.2 Co 0.5 O2 in ethanol, add 0.8 g of the monodisperse bimetallic site Zn2Co7 / CoO nanomaterial obtained in step (1), ball-mill and mix for 5 h, dry, and finally prepare monodisperse bimetallic site Zn2Co7 / CoO@Li 1.3 Mn 0.2 Co 0.5 O2 lithium-rich manganese-based cathode material.

[0087] The battery assembly is completed by the following method:

[0088] Respectively use the lithium-rich manganese-based cathode materials obtained in Examples 1-4 and Comparative Examples 1-2, and Li 1.2 Mn 0.58 Co 0.22 O2 as the cathode material, and mix it with the conductive agent acetylene black (AB) and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. Using N-methylpyrrolidone (NMP) as the solvent, place it in a small beaker and stir and mix the materials at a speed of 800 r / min for 2 h to obtain a slurry. Use an automatic coater to coat the slurry on the current collector aluminum foil, place it flat on tempered glass and transfer it to a vacuum drying oven at 85 °C for drying for 4 h. After punching to prepare a pole piece with a diameter of 12 mm, dry it in a vacuum drying oven at 105 °C for 4 h, place it in a glove box with a water content and oxygen content both lower than 0.1 ppm and filled with an argon atmosphere for 4 h to reduce the moisture adsorbed by the pole piece during the transfer process, and then assemble it into a CR2032 type button cell in the glove box. The battery uses a pure metal lithium sheet with a diameter of 16 mm and a thickness of 0.5 mm as the negative electrode, and a porous polyethylene film with a diameter of 18 mm and a model of Celgard2300 as the separator.

[0089] After the battery assembly is completed and aged for 12 h, charge-discharge tests are carried out. When the battery is at a voltage of 2-4.6 V and activated for 3 cycles at a current density of 0.1 C:

[0090] (1)The discharge specific capacity after 100 cycles at a current density of 1C, and the results are shown in Table 1 and Figure 5 as follows;

[0091] (2)The rate performance was tested at current densities of 0.1C, 1C, and 5C respectively, and the results are as Figure 6 shown.

[0092] Table 1

[0093]

[0094] As can be seen from Table 1 and Figure 5 it can be seen that the lithium-rich manganese-based cathode material after being coated with bimetallic-site anchored metal oxide composite has a higher cycle specific capacity and a higher capacity retention rate.

[0095] From Figure 6 it can be seen that the lithium-rich cathode material after being coated with bimetallic-site anchored metal oxide has excellent rate performance.

[0096] Furthermore, the cathode material finally prepared in Example 1 after the battery was cycled 100 times and Li 1.2 Mn 0.58 Co 0.22 O2 were collected respectively for HRTEM analysis, and the results are as Figure 7 and Figure 8 shown. It can be seen that the lithium-rich manganese-based cathode material after being coated with bimetallic-site anchored metal oxide has a stable phase structure, no cracks inside the structure, and a relatively complete structure. While the lithium-rich manganese-based cathode material without coating has obvious cracks inside the crystal structure, indicating that the lithium-rich manganese-based cathode material coated with bimetallic-site anchored metal oxide has more excellent stability.

[0097] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a coating material, characterized in that, Comprising the following steps: Adding an ammonia water solution to a metal salt solution of Y to conduct a first co-precipitation reaction, and then adding a metal salt solution of X to conduct a second co-precipitation reaction; the molar ratio of Y in the metal salt of Y to X in the metal salt of X is 1:0.05 - 0.1; After the second co-precipitation reaction ends, subject the slurry obtained from the reaction to solid-liquid separation, wash and dry the solid phase; The dried solid phase is subjected to a first high temperature sintering, and then a second reduction sintering to obtain X a Y b / YO x ; Wherein, X is at least one of Zn, Cu, Ni, Y is at least one of Co, Fe, Mn, 1 ≤ a ≤ 5, 1 ≤ b ≤ 7, 1 ≤ x < 1.

5.

2. The preparation method according to claim 1, wherein The metal salt of Y is at least one of nitrate and acetate; the metal salt of X is at least one of nitrate and acetate.

3. The preparation method according to claim 1 or 2, characterized in that, During the first co-precipitation reaction, the molar ratio of Y in the metal salt of Y to ammonia water is 1:2.2 - 3; the time of the first co-precipitation reaction is 2 - 8 h; during the second co-precipitation reaction, the molar ratio of X in the metal salt of X to ammonia water is 1:2 - 3; the time of the second co-precipitation reaction is 1 - 6 h.

4. The preparation method according to claim 1, characterized in that, The temperature of the first high-temperature sintering is 800 - 1100 °C; the time of the first high-temperature sintering is 4 - 20 h; the atmosphere of the second reduction sintering is a hydrogen atmosphere; The temperature of the second reduction sintering is 500 - 800 °C; the time of the second reduction sintering is 1 - 8 h.

5. A coating material, the chemical general formula of the coating material being X a Y b / YO x ; wherein, X is at least one of Zn, Cu, Ni, Y is at least one of Co, Fe, Mn, 1 ≤ a ≤ 5, 1 ≤ b ≤ 7, 1 ≤ x < 1.5; characterized in that the coating material is prepared by the preparation method according to any one of claims 1 - 4.

6. A modified lithium-rich manganese-based cathode material, characterized in that, Comprising a lithium-rich manganese-based cathode material matrix and the coating material according to claim 5 located on at least part of the surface of the matrix.

7. A preparation method of a modified lithium-rich manganese-based cathode material, characterized in that, Comprising the following steps: Disperse the lithium-rich manganese-based cathode material matrix and the coating material according to claim 5 in ethanol, ball mill, and dry to obtain the modified lithium-rich manganese-based cathode material.

8. A battery, characterized in that, Comprising the modified lithium-rich manganese-based cathode material according to claim 6 or the modified lithium-rich manganese-based cathode material prepared by the preparation method according to claim 7.

Images