Multi-metal co-doped coated positive electrode material and its preparation method and application

Abstract

The present invention discloses a multi-metal co-doped coated positive electrode material and its preparation method and application. The positive electrode material comprises a substrate and a coating layer located on the surface of the substrate, wherein the substrate is a lithium-containing layered oxide, and the coating layer is a lithium-containing layered oxide and an alkali metal ion A. n+ and high-valent metal ions B with a valence ≥ 3 n+ The alkali metal-based oxide heterostructure layer containing high-valent metals is formed by ion doping and structural reconstruction. The internal and external structural lattices are coherent and there is no obvious interface. The multi-metal co-doped and coated positive electrode material prepared by the present invention has excellent cycle stability, rate performance and conductivity; the preparation method is simple, efficient and easy to scale production.

Description

Technical Field

[0001] The present invention specifically relates to a multi-metal co-doped and coated positive electrode material and a preparation method and application thereof. Background Art

[0002] Lithium-ion batteries are simple, efficient energy storage systems. As a crucial energy storage technology for addressing the growing energy crisis, they are a key development strategy for countries including my country and have long been a research hotspot in academia and industry. Lithium-ion batteries boast the highest energy density and power density of any energy storage device. They also offer numerous advantages, including high output voltage, no memory effect, low self-discharge, high energy efficiency, long cycle life, and a wide operating temperature range.

[0003] As one of the most critical components of lithium-ion batteries, positive electrode materials are the key to achieving high energy density. Among positive electrode materials, LiCoO2 is the first lithium-containing positive electrode material to enter people's field of vision. It has high volume energy density and long cycle life. However, the high price of Co element limits its application to smaller 3C devices. In order to solve this problem and meet the needs of larger energy storage devices such as electric vehicle batteries, ternary positive electrode materials have been derived. Ternary positive electrode materials are positive electrode materials obtained by replacing part of the Co element in LiCoO2 with Ni, Mn or Al. The more common ones are LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523),LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), etc. As the Ni content increases, the ternary material can show a higher reversible capacity, but this is accompanied by a decrease in cycle performance, rate performance and safety performance. Generally speaking, researchers call NCM ternary materials with a Ni content greater than 0.5 high-nickel NCM ternary materials.

[0004] The high capacity of high-nickel materials is highly attractive. Following NCM622, NCM811 has also entered the commercialization stage. However, many challenges remain to be addressed. Specifically, the active surface chemistry leading to a high number of side reactions is a major issue for high-nickel cathode materials. The surface of high-nickel materials easily forms contaminant groups. Simply exposed to air, they react with CO2 and H2O to form LiOH and Li2CO3. This significantly increases the alkalinity of the material surface, increasing the viscosity of the slurry and, in severe cases, even causing the coating step to fail. When high-nickel ternary materials operate at high voltages, they react violently with the electrolyte, leading to loss of active material and increased electrochemical impedance during battery charge and discharge. Furthermore, the secondary spherical ternary cathode materials expand and contract significantly during charge and discharge, causing cracks and shedding of active material, resulting in performance degradation. To address these issues with NCM ternary high-nickel materials, researchers have employed a variety of modification methods to improve their cycling and rate capabilities. The most common approaches remain element doping to stabilize the structure and surface coating to inhibit interfacial side reactions. This type of method has similar modification effects in other layered oxide positive electrode materials. Generally, element doping can only achieve better results by doping the raw materials used in preparing positive electrode materials. However, it is difficult to incorporate transition metal elements into the lattice phase of the material when doping the finished positive electrode materials. The doped elements are mainly enriched on the surface, which has limited effect on the performance improvement of the material.

[0005] In summary, the layered oxide positive electrode materials currently on the market, especially the high-nickel ternary positive electrode materials, face the problems of unstable structural skeleton under high voltage and severe surface side reactions leading to performance degradation. High-nickel ternary materials have high energy density and relatively low cost, so the market potential is huge. If we want to realize the potential of these materials, these problems need to be solved urgently.

[0006] Chinese patent CN114784248B discloses a coated modified high-nickel ternary positive electrode material, which is prepared by mixing metal oxygen-containing acid powder with a high-nickel ternary positive electrode material to obtain a powder-coated high-nickel ternary positive electrode material; the powder-coated high-nickel ternary positive electrode material is then annealed to obtain a coated modified high-nickel ternary positive electrode material; Chinese patent document CN118299544A discloses a modified high-nickel ternary positive electrode, which dopes fluorine into a high-nickel ternary positive electrode material precursor structure to form a single-doped precursor; a mixture of the single-doped precursor, a tellurium source, and a lithium source is calcined for the first time to obtain a co-doped positive electrode material at different sites; the co-doped positive electrode material at different sites is washed with water, a vanadium source is added during the washing process, and then dried and calcined for a second time to obtain a modified high-nickel ternary positive electrode material in which tellurium and fluorine are co-doped at different sites and coated with lithium vanadate LiV2O4. Although these existing modification strategies can improve and enhance the cycle stability of lithium-ion positive electrode materials to a certain extent, they still cannot meet people's needs, especially the modification effect of high-nickel ternary positive electrode materials is poor. Summary of the Invention

[0007] The technical problem addressed by the present invention is to overcome the shortcomings of prior art layered cathode materials, which suffer from poor cycling stability and rate performance at high voltages, by providing a multi-metal co-doped and coated cathode material, as well as its preparation method and application. The multi-metal co-doped and coated cathode material prepared by the present invention exhibits excellent cycling stability, rate performance, and conductivity; the preparation method is simple, efficient, and amenable to large-scale production.

[0008] The present invention adopts alkali metal ion A to form lithium-containing layered oxide. n+ and high-valent metal ions B n+ During the reaction, alkali metal ions react with Li in the lithium-containing layered oxide. + Ion exchange occurs between metal ions, so that the alkali metal A with a larger ionic radius n+ Ions are doped into the surface of lithium-containing layered oxides, thereby widening the surface lattice spacing of lithium-containing layered oxides and promoting the high-valent metal B n+ Doping the interior of lithium-containing layered oxides allows high-valent metal ions to more easily penetrate the crystal lattice. The synergistic coating of the two achieves a deeper degree of modification, further stabilizing the material's crystal structure and inhibiting the diffusion of lattice oxygen from the bulk to the surface after oxidation. Furthermore, during use, side reactions between the material and the electrolyte are reduced, irreversible phase transitions are suppressed, and the conductivity and cycle stability of the lithium-containing layered oxides are significantly improved. Production personnel do not need to change the raw materials and can directly use pre-prepared cathode materials or commercial cathode materials for modification. The operation steps are simple, efficient, low-cost, and require minimal process technology.

[0009] The present invention solves the above technical problems through the following technical solutions:

[0010] The present invention provides a multi-metal co-doped positive electrode material, comprising a substrate and a coating layer located on the surface of the substrate, wherein the substrate is a lithium-containing layered oxide, and the coating layer is a lithium-containing layered oxide and an alkali metal ion A n+ and high-valent metal ions B with a valence ≥ 3 n+ "The alkali metal-based oxide heterostructure layer containing high-valent metals is formed by ion doping and structural reconstruction. The internal and external structural lattices are coherent and there is no obvious interface.

[0011] In the present invention, the formation principle of the heterogeneous structure layer is to use the alkali metal ion A with a larger ionic radius. n+ Doping broadens the lattice spacing on the surface of the lithium-containing layered oxide, assisting the high-valent metal ion B n+ By performing deeper doping, the heterostructure layer can stabilize the structure of the material under high voltage, thereby inhibiting the irreversible structural changes and interface side reactions of the positive electrode material under high voltage.

[0012] In the present invention, the internal and external structures being lattice coherent means that the internal and external structures are similar and are both layered structures.

[0013] In the present invention, the thickness of the coating layer may be 2-10 nm.

[0014] In the present invention, the ratio of the sum of the masses of the alkali metal and the high-valent metal with a valence ≥ 3 in the heterostructure layer to the mass of the lithium-containing layered oxide is preferably (0.002-0.6):1, more preferably (0.02-0.2):1, for example, 0.01:1, 0.017:1, 0.019:1, 0.02:1 or 0.04:1.

[0015] In the present invention, the ratio of the mass of the alkali metal in the heterogeneous structure layer to the mass of the lithium-containing layered oxide is preferably (0.001-0.3):1, more preferably (0.001-0.2):1.

[0016] In the present invention, the ratio of the mass of the high-valent metal with a valence ≥ 3 in the heterostructure layer to the mass of the lithium-containing layered oxide is preferably (0.001-0.3):1, more preferably (0.001-0.2):1.

[0017] In the present invention, the chemical formula of the lithium-containing layered oxide is generally Li x M y Q2 indicates that M is one or more of Ni, Co, Mn, Cu, Fe, Zn, Al and Cr, and Q is one or more of O, F, Cl, S, Se and N.

[0018] In the lithium-containing layered oxide, preferably, 0<x<2, for example, 1 or 1.2.

[0019] In the lithium-containing layered oxide, preferably, 0<y≤1, for example, 0.8 or 1.

[0020] In the present invention, the lithium-containing layered oxide can be conventional in the art, preferably one or more of lithium cobalt oxide, ternary cathode material and lithium-rich manganese material, more preferably lithium-rich manganese material. Among them, the ternary cathode material can be conventional in the art, such as Ni90 high nickel ternary cathode material, NCM523. The lithium-rich manganese material can be, for example, Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O2.

[0021] In the present invention, the lithium-containing layered oxide can be obtained from conventional commercial sources or synthesized by conventional high-temperature solid-phase methods, sol-gel methods, hydrothermal synthesis methods, or co-precipitation methods in the art.

[0022] In the present invention, the alkali metal ion A n+ Preferably Na + and / or K + .

[0023] In the present invention, the high-valent metal ion with a valence of ≥3 is preferably a transition metal ion with a valence of ≥3 and / or a main group metal ion with a valence of ≥3, and more preferably a transition metal ion with a valence of ≥3. The transition metal ion with a valence of ≥3 is preferably Ti 4+ 、Zr 4+ 、Ru 4+ 、Nb 5+ 、Ta 5+ 、Mo 6+ and W 6+ The main group metal ion with a valence of ≥3 is preferably In 3+ 、Sn 4+ and Sb 3+ One or more of .

[0024] The present invention also provides a method for preparing a multi-metal co-doped coated positive electrode material, which comprises the following steps:

[0025] Method 1:

[0026] (1) Lithium-containing layered oxide Li x M yA mixture of Q2 and a compound containing an alkali metal A is annealed to obtain a precursor; wherein the mass ratio of the alkali metal in the compound containing the alkali metal A to the lithium-containing layered oxide is (0.001-0.3):1;

[0027] (2) the precursor and the high-valent metal ion B containing a valence ≥ 3 n+ A mixture of a metal salt and / or an oxide containing a high-valent metal B with a valence ≥ 3 is annealed; wherein the high-valent metal ion B containing a valence ≥ 3 n+ The mass ratio of the high-valent metal with a valence of ≥3 in the metal salt and / or the oxide containing the high-valent metal B with a valence of ≥3 to the lithium-containing layered oxide is (0.001-0.3):1;

[0028] Or, method 2:

[0029] Lithium-containing layered oxide Li x M y Q2. Compounds containing alkali metal A and compounds containing high-valent metal ions B with a valence ≥ 3 n+ wherein the mass ratio of the alkali metal in the compound containing the alkali metal A to the lithium-containing layered oxide is (0.001-0.3):1, and the high-valent metal ion B containing the valence ≥3 is annealed. n+ The mass ratio of the high-valent metal with a valence ≥3 in the metal salt and / or the oxide containing the high-valent metal B with a valence ≥3 to the lithium-containing layered oxide is (0.001-0.3):1.

[0030] In the present invention, the lithium-containing layered oxide is as described above and will not be described again here.

[0031] In the present invention, the alkali metal A is preferably Na and / or K.

[0032] In the present invention, the compound containing alkali metal A is preferably one or more of a metal salt containing alkali metal A, a base containing alkali metal A and an oxide containing alkali metal A, for example, a metal salt containing alkali metal A or a base containing alkali metal A.

[0033] The salt containing alkali metal A may be sodium carbonate, sodium bicarbonate, potassium carbonate or potassium bicarbonate. The base containing alkali metal A may be sodium hydroxide or potassium hydroxide. The oxide containing alkali metal A may be sodium oxide or potassium oxide.

[0034] In the present invention, the mass ratio of the alkali metal in the compound containing the alkali metal A to the lithium-containing layered oxide is preferably (0.001-0.2):1, for example, 0.005:1, 0.01:1, 0.02:1, 0.05:1 or 0.1:1.

[0035] In the present invention, the high-valent metal with a valence ≥3 is preferably a transition metal with a valence ≥3 and / or a main group metal with a valence ≥3, more preferably a transition metal with a valence ≥3.

[0036] Among them, the transition metal with a valence ≥3 is preferably one or more of Ti, Zr, Ru, Nb, Ta, Mo and W.

[0037] Wherein, the main group metal with a valence ≥ 3 is preferably one or more of In, Sn and Sb.

[0038] In the present invention, the high-valent metal ion B containing a valence ≥ 3 n+ The metal salt is preferably a high-valent metal ion B containing a valence ≥ 3 n+ The alkoxide and / or ammonium salt thereof may be, for example, tetrabutyl zirconate, tetrabutyl titanate, ammonium niobium oxalate, ammonium molybdate, ammonium tungstate, antimony nitrate, or indium nitrate. The oxide containing a high-valent metal B with a valence ≥ 3 may be, for example, tungsten oxide, molybdenum oxide, titanium oxide, zirconium oxide, niobium oxide, tantalum oxide, indium oxide, tin dioxide, or antimony oxide.

[0039] In the present invention, the high-valent metal ion B containing a valence ≥ 3 n+ The mass ratio of the high-valent metal with a valence ≥3 in the metal salt and / or the oxide containing the high-valent metal B with a valence ≥3 to the lithium-containing layered oxide is preferably (0.001-0.2):1, for example, 0.005:1, 0.007:1, 0.009:1, 0.01:1, 0.02:1 or 0.1:1.

[0040] Method 1, in step (1), the annealing temperature is preferably 400-1000°C, more preferably 500-800°C, for example, 550°C, 650°C or 700°C. The annealing time can be 4-24 hours, preferably 6-24 hours, for example, 10 hours, 15 hours or 20 hours. The rate of heating to the annealing temperature is preferably 1-10°C / min, for example, 5°C / min. The annealing is generally carried out in air or oxygen atmosphere.

[0041] Method 1: In step (1), the mixture is preferably subjected to slight water mixing, solid phase mixing or liquid phase mixing before the annealing treatment.

[0042] The micro-water mixing preferably comprises the following steps: stirring and evaporating the solution containing the mixture to dryness. The solvent in the solution can be conventional in the art, such as one or more of deionized water, ethanol, acetone, DMF, ethylenediamine, and triethylamine. The amount of the solvent used can be conventional in the art, generally sufficient to immerse the solid material. Preferably, the ratio of the mass of the lithium-containing layered oxide to the volume of the solvent can be (0.5-2) g / mL, such as 1 g / mL, 1.5 g / mL, or 2 g / mL. The evaporation process is preferably carried out under stirring.

[0043] The solid phase mixing preferably comprises the following step: grinding the mixture for 10-100 minutes, such as 30 minutes or 50 minutes.

[0044] Wherein, the liquid phase mixing preferably includes the following steps: the solution containing the mixture is fully stirred at 15-200°C, followed by solid-liquid separation and drying. The solvent in the solution may be conventional in the art, preferably one or more of deionized water, ethanol, acetone, DMF, ethylenediamine and triethylamine. The amount of the solvent in the solution may be conventional in the art, preferably, the ratio of the mass of the lithium-containing layered oxide to the volume of the solvent may be (0.2-1) g / mL, for example, 0.5 g / mL. The stirring time may be 0.5-48h, preferably 12-24h. The solid-liquid separation method may be conventional in the art, such as filtration. The drying method may be conventional in the art, such as drying.

[0045] When the mixture is subjected to the micro-water mixing or the solid-phase mixing, the mass ratio of the alkali metal in the compound containing the alkali metal A to the lithium-containing layered oxide is preferably (0.001-0.1):1, for example, 0.005:1, 0.01:1, 0.02:1, 0.05:1 or 0.1:1.

[0046] When the mixture is subjected to the liquid-phase mixing, the mass ratio of the alkali metal in the compound containing the alkali metal A to the lithium-containing layered oxide is preferably (0.05-0.2):1, for example, 0.05:1 or 0.1:1.

[0047] When the mixture is mixed in liquid phase, some of the compound containing alkali metal A will remain in the solution after solid-liquid separation, resulting in waste of raw materials. Therefore, the amount of the compound containing alkali metal A can be appropriately increased.

[0048] Method 1: In step (1), according to conventional practice in the art, after the annealing treatment, the material is generally required to be naturally cooled to room temperature.

[0049] In step (2) of method 1 and / or method 2, the mixture is preferably subjected to slight water mixing, solid phase mixing or liquid phase mixing before annealing. The operations and conditions of slight water mixing, solid phase mixing and liquid phase mixing are as described above and will not be described again here. In some preferred embodiments, when the raw material is the high-valent metal ion B containing a valence ≥ 3, n+ When the raw material is a metal salt containing a high-valent metal B with a valence ≥ 3, the mixture is subjected to solid-phase mixing before the annealing.

[0050] When the mixture is subjected to the micro-water mixing or the solid phase mixing, the high-valent metal ion B containing a valence of ≥3 n+ The mass ratio of the high-valent metal with a valence ≥ 3 in the metal salt and / or the oxide containing the high-valent metal B with a valence ≥ 3 to the lithium-containing layered oxide is preferably (0.005-0.1):1, for example, 0.005:1, 0.01:1, 0.02:1, 0.05:1 or 0.1:1.

[0051] When the liquid phase mixing is performed on the mixture, the high-valent metal ion B containing a valence of ≥3 n+ The mass ratio of the high-valent metal with a valence ≥ 3 in the metal salt and / or the oxide containing the high-valent metal B with a valence ≥ 3 to the lithium-containing layered oxide is preferably (0.05-0.2):1, for example 0.05:1 or 0.1:1.

[0052] Method 1, in step (2), the annealing temperature may be 200-1000°C, preferably 400-800°C, such as 550°C, 650°C, or 700°C. The annealing time may be 0.5-24 hours, preferably 8-24 hours, such as 10 hours, 15 hours, or 20 hours. The rate of heating to the annealing temperature is preferably 1-10°C / min, such as 5°C / min.

[0053] In method 2, the annealing temperature may be 300-1000°C, preferably 400-800°C, such as 550°C, 650°C, or 700°C. The annealing time may be 0.5-24 hours, preferably 8-24 hours, such as 10 hours, 15 hours, or 20 hours. The heating rate to the annealing temperature is preferably 1-10°C / min, such as 5°C / min.

[0054] In step (2) of method 1 and / or method 2, the annealing is generally performed in air or oxygen atmosphere. When the lithium-containing layered oxide is a ternary cathode material with a high Ni content or a lithium-manganese-rich material, the annealing is preferably performed in an oxygen atmosphere.

[0055] In the present invention, when the method is adopted, the multi-metal co-doped and coated positive electrode material prepared is more evenly coated, has a deeper doping degree, and has better cycle stability.

[0056] The present invention also provides a multi-metal co-doped and coated positive electrode material prepared by the above-mentioned preparation method.

[0057] In the present invention, the multi-metal co-doped coated positive electrode material preferably comprises a substrate and a coating layer located on the surface of the substrate, wherein the substrate is a lithium-containing layered oxide, and the coating layer is a lithium-containing layered oxide and an alkali metal ion A n+ and high-valent metal ions B with a valence ≥ 3 n+ "The alkali metal-based oxide heterostructure layer containing high-valent metals is formed by ion doping and structural reconstruction. The internal and external structural lattices are coherent and there is no obvious interface.

[0058] The present invention also provides a use of the multi-metal co-doped and coated positive electrode material as described above in a lithium-ion battery.

[0059] On the basis of conforming to the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0060] The reagents and raw materials used in the present invention are commercially available.

[0061] The positive progress effect of the present invention is:

[0062] (1) The multi-metal co-doped and coated lithium-ion battery cathode material prepared by the present invention has excellent cycle stability and rate performance; the method can alleviate the side reaction between the material and the electrolyte surface, thereby achieving the improvement of the electrochemical performance of the material at high voltage;

[0063] (2) The preparation method of the present invention is simple, efficient, low-cost, has low technical requirements, and is easy to produce on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 This is a scanning electron microscope photograph of the Na-W co-coated high-nickel cathode material prepared in Example 1;

[0065] Figure 2 This is a transmission electron micrograph of the Na-W co-coated high-nickel cathode material prepared in Example 1;

[0066] Figure 3 This is the powder X-ray diffraction pattern of the Na-W co-coated high-nickel cathode material prepared in Example 1;

[0067] Figure 4The charge-discharge curves of the Ni90 high-nickel ternary positive electrode material of Comparative Example 1 and the Na-W co-coated high-nickel positive electrode material prepared in Example 1 at 3-4.3V;

[0068] Figure 5 Comparison of the half-cell cycle performance at 3-4.3V between the Na-W co-coated high-nickel cathode material (Na-W@Ni90) prepared in Example 1 and the Ni90 high-nickel ternary cathode material (Ni90) of Comparative Example 1;

[0069] Figure 6 Comparison of the half-cell cycle performance at 3-4.6 V between the Na-W coated modified lithium cobalt oxide material (Na-W@LCO) prepared in Example 12 and the uncoated lithium cobalt oxide cathode material (LCO) in Comparative Example 3;

[0070] Figure 7 Comparison of the soft pack cycling performance at 3-4.5V between the Na-W coated modified lithium cobalt oxide material (Na-W@LCO) prepared in Example 12 and the uncoated lithium cobalt oxide positive electrode material (LCO) in Comparative Example 3;

[0071] Figure 8 The half-cell cycle performance of the Na-Zr-coated modified lithium-rich manganese cathode material (Na-Zr@LLMO) prepared in Example 16 and the uncoated lithium-rich manganese cathode material (LLMO) in Comparative Example 4 at 2-4.8V is compared.

[0072] Figure 9 The half-cell cycle performance of the Na-Zr coated modified high nickel positive electrode materials prepared in Examples 19 and 20 and the uncoated high nickel positive electrode material in Comparative Example 1 at 2-4.8V is compared. DETAILED DESCRIPTION

[0073] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions, or selected according to the product specifications.

[0074] The molecular formula of ammonium tungstate used in the following examples and comparative examples is (NH4) 10 W 12 O 41 ·xH2O, with a molecular weight of 3060.46 g / mol; the molecular formula of ammonium niobium oxalate is C4H4NNbO9·xH2O, with a molecular weight of 302.98 g / mol.

[0075] Example 1

[0076] Weigh 10g of Ni90 high-nickel ternary positive electrode material (Rongbai S90E) and 0.23g of sodium carbonate into a beaker, add 10mL of water, heat and stir until evaporated, and then place the obtained mixture in a tube furnace in an oxygen atmosphere and calcine with a heating rate of 5℃ / min, keep warm at 650℃ for 10h, and cool naturally to room temperature to obtain a Na-doped precursor; then all the Na-doped precursors are placed in 10mL of an aqueous solution containing 0.14g of ammonium tungstate, heated and stirred until evaporated, and placed in a tube furnace in an oxygen atmosphere again and calcined with a heating rate of 5℃ / min, keep warm at 650℃ for 10h, and cool naturally to room temperature to obtain a Na-W co-coated high-nickel positive electrode material.

[0077] Example 2

[0078] Weigh 10g of Ni90 high-nickel ternary positive electrode material (Rongbai S90E) and 0.23g of sodium carbonate into a beaker, add 10mL of water, heat and stir until evaporated, and then place the obtained mixture in a tube furnace in an oxygen atmosphere and calcine at a heating rate of 5℃ / min. Keep it at 550℃ for 10h and cool it naturally to room temperature to obtain a Na-doped precursor; then place all the Na-doped precursors in 10mL of aqueous solution containing 0.14g of ammonium tungstate and heat and stir until evaporated, and place it in a tube furnace in an oxygen atmosphere again and calcine at a heating rate of 5℃ / min. Keep it at 650℃ for 10h and cool it naturally to room temperature to obtain a Na-W co-coated high-nickel positive electrode material.

[0079] Example 3

[0080] Weigh 10g of Ni90 high-nickel ternary positive electrode material (Rongbai S90E) and 0.23g of sodium carbonate into a beaker, add 10mL of water, heat and stir until evaporated, and then place the obtained mixture in a tube furnace in an oxygen atmosphere and calcine with a heating rate of 5℃ / min, keep warm at 650℃ for 10h, and cool naturally to room temperature to obtain a Na-doped precursor; then all the Na-doped precursors are placed in 10mL of an aqueous solution containing 0.14g of ammonium tungstate, heated and stirred until evaporated, and placed in a tube furnace in an oxygen atmosphere again and calcined with a heating rate of 5℃ / min, keep warm at 550℃ for 10h, and cool naturally to room temperature to obtain a Na-W co-coated high-nickel positive electrode material.

[0081] Example 4

[0082] Weigh 10g of Ni90 high-nickel ternary positive electrode material (Rongbai S90E) and 0.23g of sodium carbonate into a beaker, add 10mL of water, heat and stir until evaporated, and then place the obtained mixture in a tube furnace in an oxygen atmosphere and calcine with a heating rate of 5℃ / min, keep warm at 650℃ for 10h, and cool naturally to room temperature to obtain a Na-doped precursor; then all the Na-doped precursors are placed in 10mL of an aqueous solution containing 0.14g of ammonium tungstate, heated and stirred until evaporated, and placed in a tube furnace in an oxygen atmosphere again and calcined with a heating rate of 5℃ / min, keep warm at 650℃ for 20h, and cool naturally to room temperature to obtain a Na-W co-coated high-nickel positive electrode material.

[0083] Example 5

[0084] 10.0 g of NCM523 ternary cathode material and 0.17 g of sodium hydroxide were weighed into a beaker, 10 mL of water was added, and the mixture was heated and stirred until evaporated. The resulting mixture was then placed in a tubular furnace in an oxygen atmosphere and calcined at a heating rate of 5 ° C / min, kept at 650 ° C for 10 h, and naturally cooled to room temperature to obtain a Na-doped precursor; all the Na-doped precursors were placed in 10 mL of an aqueous solution containing 0.14 g of ammonium tungstate and heated and stirred until evaporated. Finally, the resulting mixture was placed in a tubular furnace in an oxygen atmosphere and calcined at a heating rate of 5 ° C / min, kept at 650 ° C for 10 h, and naturally cooled to room temperature to obtain a Na-W co-coated ternary cathode material.

[0085] Example 6

[0086] Weigh 10.0g of Ni90 high-nickel ternary positive electrode material and 0.14g of potassium hydroxide into a beaker, add 10mL of water, heat and stir until evaporated, then place the obtained mixture in a tubular furnace in an oxygen atmosphere and calcine with a heating rate of 5℃ / min, keep warm at 650℃ for 10h, and cool naturally to room temperature to obtain a K-doped precursor; then place all the K-doped precursors in 10mL of an aqueous solution containing 0.14g of ammonium tungstate, heat and stir until evaporated, and place it in a tubular furnace in an oxygen atmosphere and calcine again with a heating rate of 5℃ / min, keep warm at 650℃ for 10h, and cool naturally to room temperature to obtain a KW-coated high-voltage ternary positive electrode material.

[0087] Example 7

[0088] Weigh 10.0 g of NCM523 ternary cathode material and 0.14 g of potassium hydroxide into a beaker, add 10 mL of water, heat and stir until evaporated, then place the obtained mixture in a tubular furnace in an oxygen atmosphere and calcine at a heating rate of 5 ° C / min, keep warm at 650 ° C for 10 hours, and cool naturally to room temperature to obtain a K-doped precursor; then place all the K-doped precursors in 10 mL of an aqueous solution containing 0.14 g of ammonium tungstate, heat and stir until evaporated, and place it in a tubular furnace in an oxygen atmosphere again and calcine at a heating rate of 5 ° C / min, keep warm at 650 ° C for 10 hours, and cool naturally to room temperature to obtain a KW-coated high-voltage ternary cathode material.

[0089] Example 8

[0090] Weigh 10.0g of NCM523 ternary positive electrode material and 0.14g of potassium hydroxide into a beaker, add 10mL of water, heat and stir until evaporated, then place the obtained mixture in a tube furnace in an oxygen atmosphere and calcine at a heating rate of 5℃ / min, keep warm at 650℃ for 10h, and cool naturally to room temperature to obtain a K-doped precursor; then place all the K-doped precursors in 10mL of ethanol solution containing 0.31g of tetrabutyl zirconate, heat and stir until evaporated, and place it in a tube furnace in an oxygen atmosphere again and calcine at a heating rate of 5℃ / min, keep warm at 650℃ for 10h, and cool naturally to room temperature to obtain a K-Zr co-coated high-voltage ternary positive electrode material.

[0091] Example 9

[0092] Weigh 10.0 g of NCM523 ternary positive electrode material and 0.17 g of sodium hydroxide into a beaker, add 10 mL of water, heat and stir until evaporated, then place the obtained mixture in a tube furnace in an oxygen atmosphere and calcine it with a heating rate of 5 ° C / min, keep it at 650 ° C for 10 hours, and naturally cool to room temperature to obtain a Na-doped precursor; then all the Na-doped precursors and 0.055 g of tungsten oxide and 0.071 g of niobium pentoxide are mixed and ground for 30 minutes. Finally, the obtained mixture is placed in a tube furnace in an oxygen atmosphere and calcined with a heating rate of 5 ° C / min, keep it at 650 ° C for 10 hours, and naturally cool to room temperature to obtain a Na-W / Nb co-coated high-voltage ternary positive electrode material.

[0093] Example 10

[0094] Weigh 10.0 g of NCM523 ternary positive electrode material and 0.17 g of sodium hydroxide in a beaker, add 10 mL of water, heat and stir until evaporated, then place the resulting mixture in a tube furnace in an oxygen atmosphere and calcine at a heating rate of 5 ° C / min, keep warm at 650 ° C for 10 hours, and naturally cool to room temperature to obtain a Na-doped precursor; then all the Na-doped precursors and 0.15 g of molybdenum oxide are mixed and ground for 30 minutes, and finally the resulting mixture is placed in a tube furnace in an oxygen atmosphere and calcined at a heating rate of 5 ° C / min, keep warm at 650 ° C for 10 hours, and naturally cool to room temperature to obtain a Na-Mo co-coated high-voltage ternary positive electrode material.

[0095] Example 11

[0096] Weigh 10.0g of NCM523 ternary positive electrode material and 0.14g of potassium hydroxide into a beaker, add 10mL of water, heat and stir until evaporated, then place the obtained mixture in a tube furnace in an oxygen atmosphere and calcine at a heating rate of 5℃ / min, keep warm at 650℃ for 10h, and naturally cool to room temperature to obtain a K-doped precursor; then all the K-doped precursors and 0.15 molybdenum oxide are mixed and ground for 30min, and the obtained mixture is placed in a tube furnace in an oxygen atmosphere and calcined again at a heating rate of 5℃ / min, keep warm at 650℃ for 10h, and cool to room temperature to obtain a K-Mo co-coated high-voltage ternary positive electrode material.

[0097] Example 12

[0098] Weigh 10.0 g of lithium cobalt oxide positive electrode material and 0.23 g of sodium carbonate into a beaker, add 10 mL of water, heat and stir until evaporated, then place the mixture in a muffle furnace and calcine at a heating rate of 5 ° C / min, keep warm at 650 ° C for 10 hours, and cool naturally to room temperature to obtain a Na-doped precursor; then place all the Na-doped precursors in 10 mL of an aqueous solution containing 0.14 g of ammonium tungstate and heat and stir until evaporated, then place the mixture in a muffle furnace and calcine at a heating rate of 5 ° C / min, keep warm at 650 ° C for 10 hours, and cool to room temperature to obtain Na-W coated modified high-pressure lithium cobalt oxide.

[0099] Example 13

[0100] Weigh 10.0 g of lithium cobalt oxide positive electrode material and 0.17 g of potassium carbonate into a beaker, add 10 mL of water, heat and stir until evaporated, then place the mixture in a muffle furnace and calcine at a heating rate of 5 ° C / min, keep warm at 650 ° C for 10 hours, and cool naturally to room temperature to obtain a Na-doped precursor; then place all the K-doped precursors in 10 mL of ethanol solution containing 0.21 g of ammonium niobium oxalate, heat and stir until evaporated, then place the mixture in a muffle furnace and calcine at a heating rate of 5 ° C / min, keep warm at 650 ° C for 10 hours, and cool to room temperature to obtain K-Nb coated modified high-pressure lithium cobalt oxide.

[0101] Example 14

[0102] Weigh 10.0g of Ni90 high-nickel ternary positive electrode material and 0.17g of potassium carbonate into a beaker, add 10mL of water, heat and stir until evaporated, then place the mixture in a tubular furnace in an oxygen atmosphere and calcine at a heating rate of 5℃ / min, keep warm at 650℃ for 10h, and cool naturally to room temperature to obtain a Na-doped precursor; then place all the Na-doped precursors in 10mL of ethanol solution containing 0.31g of tetrabutyl zirconate and heat and stir until evaporated, finally place the mixture in a tubular furnace in an oxygen atmosphere and calcine at a heating rate of 5℃ / min, keep warm at 650℃ for 10h, and cool naturally to room temperature to obtain a K-Zr co-coated high-voltage ternary positive electrode material.

[0103] Example 15

[0104] Weigh 10.0g of NCM523 ternary positive electrode material and 0.23g of sodium carbonate into a beaker, add 10mL of water, heat and stir until evaporated, then place the mixture in a tubular furnace in an oxygen atmosphere and calcine at a heating rate of 5℃ / min, keep warm at 650℃ for 10h, and cool naturally to room temperature to obtain a Na-doped precursor; then place all the Na-doped precursors in 10mL of an aqueous solution containing 0.21g of ammonium niobium oxalate and heat and stir until evaporated, finally place the mixture in a tubular furnace in an oxygen atmosphere and calcine at a heating rate of 5℃ / min, keep warm at 650℃ for 10h, and cool naturally to room temperature to obtain a Na-Nb co-coated high-voltage ternary positive electrode material.

[0105] Example 16

[0106] Weigh 10.0 g of lithium-rich manganese positive electrode material (Li 1.2 Mn 0.54 Ni 0.13 Co 0.13O2) and 0.23g of sodium carbonate are added to a beaker with 10mL of water and heated with stirring until evaporated to dryness, and then the obtained mixture is placed in a tubular furnace in an oxygen atmosphere and calcined at a heating rate of 5°C / min, kept at 650°C for 10h, and naturally cooled to room temperature to obtain a Na-doped precursor; then all the Na-doped precursors are placed in 10mL of ethanol solution containing 0.31g of tetrabutyl zirconate and heated with stirring until evaporated to dryness, and finally the obtained mixture is placed in a tubular furnace in an oxygen atmosphere and calcined at a heating rate of 5°C / min, kept at 650°C for 10h, and naturally cooled to room temperature to obtain a Na-Zr co-coated lithium manganese-rich positive electrode material.

[0107] Example 17

[0108] Weigh 10.0 g of lithium-rich manganese positive electrode material (Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O2) and 0.23g of sodium carbonate are added to a beaker with 10mL of water, heated and stirred until evaporated, and then the mixture is placed in a tubular furnace in an oxygen atmosphere and calcined at a heating rate of 5°C / min, kept at 650°C for 10 hours, and naturally cooled to room temperature to obtain a Na-doped precursor; then all the Na-doped precursors and 0.13g of tin dioxide are mixed and ground, and finally the obtained mixture is placed in a tubular furnace in an oxygen atmosphere and calcined at a heating rate of 5°C / min, kept at 650°C for 10 hours, and naturally cooled to room temperature to obtain a Na-Sn co-coated lithium manganese-rich positive electrode material.

[0109] Example 18

[0110] Weigh 10.0 g of lithium-rich manganese positive electrode material (Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O2) and 0.23g of sodium carbonate were added to a beaker, 10mL of water was added, and the mixture was heated and stirred until evaporated to dryness. The mixture was then placed in a tubular furnace in an oxygen atmosphere and calcined at a heating rate of 5°C / min, kept at 650°C for 10h, and naturally cooled to room temperature to obtain a Na-doped precursor; all the Na-doped precursors were then mixed and ground with 0.065g of tin dioxide and 0.055g of tungsten oxide. Finally, the mixture was placed in a tubular furnace in an oxygen atmosphere and calcined at a heating rate of 5°C / min, kept at 650°C for 10h, and naturally cooled to room temperature to obtain a Na-Sn / W co-coated lithium-rich manganese positive electrode material.

[0111] Example 19

[0112] Weigh 10.0g of Ni90 high-nickel ternary positive electrode material and 0.17g of sodium hydroxide into a beaker, add 10mL of water, heat and stir until evaporated, then place the mixture in a tube furnace in an oxygen atmosphere and calcine with a heating rate of 5℃ / min, keep warm at 650℃ for 10h, and cool naturally to room temperature to obtain a Na-doped precursor; then place all the Na-doped precursors in 10mL of ethanol solution containing 0.31g of tetrabutyl zirconate and heat and stir until evaporated, finally place the mixture in a tube furnace in an oxygen atmosphere and calcine with a heating rate of 5℃ / min, keep warm at 650℃ for 10h, and cool naturally to room temperature to obtain a Na-Zr co-coated high-nickel positive electrode material.

[0113] Example 20

[0114] 10 g of Ni90 high-nickel ternary positive electrode material (Rongbai S90E) was weighed and placed in 10 mL of ethanol solution containing 0.17 g of sodium hydroxide and 0.31 g of tetrabutyl zirconate, heated and stirred until evaporated to dryness, and then placed in a tubular furnace in an oxygen atmosphere and calcined again at a heating rate of 5 ° C / min. It was kept at 650 ° C for 10 h and naturally cooled to room temperature to obtain a Na-Zr co-coated high-nickel positive electrode material.

[0115] Example 21

[0116] Weigh 10g of Ni90 high-nickel ternary positive electrode material (Rongbai S90E) and 1.7g of sodium hydroxide into a beaker, add 20mL of water and stir at room temperature for 30min, then perform vacuum filtration, dry the separated solid and calcine it in a tube furnace in an oxygen atmosphere with a heating rate of 5℃ / min, keep it at 650℃ for 10h, and cool it naturally to room temperature to obtain a Na-doped precursor; then place all the Na-doped precursors in 10mL of an aqueous solution containing 0.14g of ammonium tungstate, heat and stir until evaporated, and place it in a tube furnace in an oxygen atmosphere again and calcine it with a heating rate of 5℃ / min, keep it at 650℃ for 10h, and cool it naturally to room temperature to obtain a Na-W synergistically coated high-nickel positive electrode material.

[0117] Example 22

[0118] 10g of Ni90 high-nickel ternary positive electrode material (Rongbai S90E) and 0.23g of potassium carbonate were weighed and solid-phase ground for 30min. The resulting mixture was then placed in a tubular furnace in an oxygen atmosphere and calcined at a heating rate of 5°C / min. The mixture was kept at 650°C for 10h and naturally cooled to room temperature to obtain a K-doped precursor. The entire K-doped precursor was then placed in a 10mL ethanol solution containing 0.71g of tetrabutyl titanate and heated with stirring until evaporated to dryness. The mixture was then placed in a tubular furnace in an oxygen atmosphere and calcined again at a heating rate of 5°C / min. The mixture was kept at 650°C for 10h and naturally cooled to room temperature to obtain a K-Ti synergistically coated high-nickel positive electrode material.

[0119] Comparative Example 1

[0120] Ni90 high nickel ternary positive electrode material.

[0121] Comparative Example 2

[0122] NCM523 ternary positive electrode material.

[0123] Comparative Example 3

[0124] Lithium cobalt oxide positive electrode material.

[0125] Comparative Example 4

[0126] Lithium-rich manganese (Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O2) positive electrode material.

[0127] Effect embodiment

[0128] (1) Sample characterization

[0129] Figure 1 This is a scanning electron microscope photograph of the Na-W co-coated high-nickel positive electrode material prepared in Example 1. From the figure, it can be seen that the coated high-nickel ternary positive electrode material is about 1 μm. Figure 2 This is a transmission electron microscope photograph of the Na-W co-coated high-nickel positive electrode material prepared in Example 1. From the figure, it can be seen that there is a heterogeneous structure coating layer on the surface of the high-nickel ternary positive electrode material. The coating layer is mainly generated by the reaction of lithium-containing layered oxides and "alkali metal ions and transition metal ions". It is uniformly coated on the surface of the high-nickel ternary positive electrode material. The internal and external structural lattices are coherent, both are layered structures, and there is no obvious interface. Figure 3 The powder X-ray diffraction pattern of the Na-W co-coated high nickel cathode material prepared in Example 1 is as follows: Figure 1 It can be seen that the high nickel ternary positive electrode material after coating and modification does not show other impurity diffraction peaks.

[0130] (2) Electrochemical performance test

[0131] Half-cell performance test: The electrochemical performance of the prepared positive electrode material was evaluated using a CR2016 button cell. The button cell negative electrode was a 1 mm thick, 15 mm diameter lithium metal sheet. 0.16 g of the final products prepared in Examples 1-6, Examples 12-14, and Examples 16-22, as well as the positive electrode materials of Comparative Examples 1-4, 0.02 g of conductive acetylene black, and 1 mL of a PVDF solution in N-dimethylpyrrolidone (PVDF concentration of 20 mg / mL) were weighed and stirred to prepare a slurry. The slurry was then coated onto carbon-coated aluminum foil, dried in a vacuum oven at 120°C, and then cut into 14 mm diameter positive electrode sheets using a sheet punch. The active material loading on the positive electrode sheets was 3-4 mg. The battery was assembled in a glove box using a glass fiber separator from Whatman and a 1M lithium hexafluorophosphate electrolyte (solvents were EC and DMC, with a solvent volume ratio of EC:DMC = 1:1). The oxygen and water vapor levels were both below 0.1 ppm during assembly. Electrochemical testing was performed using a Shanghai Chenhua CHI760e electrochemical workstation and a Landian LAND-CT2001C battery test system. The test results are shown in Tables 1 and Figure 4-Figure 6 、 Figure 8 .

[0132] Full battery performance test: The Na-W coated modified lithium cobalt oxide material prepared in Example 12, conductive carbon and PVDF were weighed in a weight ratio of 94:3:3 and mixed with NMP to prepare a positive electrode slurry. The slurry was then coated on aluminum foil on both sides to prepare a positive electrode sheet with an area density of 14.5 mg cm per surface. -2 The silicon-carbon negative electrode material, conductive carbon, dispersant sodium carboxymethyl cellulose, and binder polyacrylic acid were weighed in a weight ratio of 90:5:1:4 and then mixed with water to prepare a negative electrode slurry. The slurry was then coated on both sides of copper foil to prepare a negative electrode sheet with a single-side surface density of 8.5 mg cm -2 The electrolyte is 1M lithium hexafluorophosphate solution, the solvent volume ratio is EC:DMC=1:1, about 3.5g (Ah) -1 , N / P ratio is controlled at 1.05-1.10, test results are shown in Figure 7 .

[0133] Table 1

[0134]

[0135]

[0136] from Figure 4 It can be seen that the initial specific capacity of the high nickel ternary cathode after coating modification is improved, and the first efficiency is also significantly improved. Figure 5It can be seen that the cycle stability of the high-nickel ternary positive electrode material after coating and modification is significantly improved. The capacity retention rate of the high-nickel ternary positive electrode material before modification is 77.5% after 200 cycles at a 1C rate, and the capacity retention rate of the high-nickel ternary positive electrode material after modification is increased to 99% after 200 cycles at a 1C rate. Figure 6 It can be seen that the cycle stability of lithium cobalt oxide before and after coating modification at a high voltage of 4.6V is significantly improved. The capacity retention rate of lithium cobalt oxide before modification is 37% after 500 cycles at a 1C rate, and the capacity retention rate of the modified lithium cobalt oxide positive electrode material after 500 cycles at a 1C rate is 80.2%. Figure 7 The soft pack test data shows that the capacity retention rate of lithium cobalt oxide before coating modification is 87% after 30 cycles at a high voltage of 4.5V. The capacity retention rate of the modified lithium cobalt oxide positive electrode material after 30 cycles at a high voltage of 4.5V is 98.1%, and the cycle stability is significantly improved. Figure 8 It can be seen that the cycle stability of lithium-rich manganese before and after coating modification is significantly improved. The initial capacity of lithium-rich manganese before modification is 205mAh / g at a 1C rate, and the capacity retention rate is 62.5% after 300 cycles. The initial capacity of the modified lithium cobalt oxide positive electrode material at a 1C rate is 250mAh / g, and the capacity retention rate after 300 cycles is 89.8%. Figure 9 It can be seen that the cycle stability of the high-nickel positive electrode material is significantly improved before and after coating modification, and the performance of the two-step coating modification is slightly better than that of the one-step coating modification. The capacity retention rate of the high-nickel positive electrode material modified by the two-step coating method is 96.2% after 100 cycles, and the capacity retention rate of the high-nickel positive electrode material modified by the one-step coating method is 93.1% after 100 cycles.

[0137] Although specific embodiments of the present invention have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, and such changes and modifications are intended to fall within the scope of the present invention.

Claims

1. A multi-metal co-doped coated positive electrode material, characterized in that: The invention comprises a substrate and a coating layer located on the surface of the substrate, wherein the substrate is a lithium-containing layered oxide, and the coating layer is a lithium-containing layered oxide and an alkali metal ion A n+ and high-valent metal ions B with a valence ≥ 3 n+ "The alkali metal-based layered oxide heterostructure layer containing a high-valent metal is formed by ion doping and structural reconstruction, and the internal and external structural lattices are coherent and have no obvious interface; wherein the ratio of the sum of the mass of the alkali metal and the high-valent metal with a valence ≥3 in the heterostructure layer to the mass of the lithium-containing layered oxide is (0.002-0.6):

1.

2. The multi-metal co-doped coated positive electrode material according to claim 1, characterized in that: The ratio of the sum of the mass of the alkali metal and the high-valent metal with a valence of ≥3 in the heterostructure layer to the mass of the lithium-containing layered oxide is (0.02-0.2):1; And / or, the chemical formula of the lithium-containing layered oxide is Li x M y Q2, M is one or more of Ni, Co, Mn, Cu, Fe, Zn, Al and Cr, and Q is one or more of O, F, Cl, S, Se and N; And / or, the lithium-containing layered oxide is one or more of lithium cobalt oxide, a ternary cathode material and a lithium-rich manganese material; and / or, the coating layer has a thickness of 2-10 nm; And / or, the alkali metal ion A n+ for Na + and / or K + ; And / or, the high-valent metal ion with a valence ≥3 is a transition metal ion with a valence ≥3 and / or a main group metal ion with a valence ≥3.

3. The multi-metal co-doped coated positive electrode material according to claim 2, characterized in that: The transition metal ion B with a valence of ≥3 n+ Ti 4+ 、Zr 4+ 、Ru 4+ 、Nb 5+ 、Ta 5+ 、Mo 6+ and W 6+ One or more of .

4. The multi-metal co-doped coated positive electrode material according to claim 2, characterized in that: The main group metal ion with a valence of ≥3 is In 3+ 、Sn 4+ and Sb 3+ One or more of .

5. A method for preparing a multi-metal co-doped coated positive electrode material according to any one of claims 1 to 4, characterized in that: It includes the following steps: Method 1: (1) Lithium-containing layered oxide Li x M y Annealing a mixture of Q2 and a compound containing an alkali metal A to obtain a precursor; wherein the mass ratio of the alkali metal in the compound containing the alkali metal A to the lithium-containing layered oxide is (0.001-0.3):1; (2) the precursor and the high-valent metal ion B containing a valence ≥ 3 n+ A mixture of a metal salt and / or an oxide containing a high-valent metal B with a valence ≥ 3 is annealed; wherein the high-valent metal ion B containing a valence ≥ 3 n+ The mass ratio of the high-valent metal with a valence ≥ 3 in the metal salt and / or the oxide containing the high-valent metal B with a valence ≥ 3 to the lithium-containing layered oxide is (0.001-0.3): 1; Or, method 2: Lithium-containing layered oxide Li x M y Q2. Compounds containing alkali metal A and compounds containing high-valent metal ions B with a valence ≥ 3 n + wherein the mass ratio of the alkali metal in the compound containing the alkali metal A to the lithium-containing layered oxide is (0.001-0.3):1, and the high-valent metal ion B containing the valence ≥3 is annealed. n+ The mass ratio of the high-valent metal with a valence ≥3 in the metal salt and / or the oxide containing the high-valent metal B with a valence ≥3 to the lithium-containing layered oxide is (0.001-0.3):

1.

6. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 5, characterized in that: The chemical formula of the lithium-containing layered oxide is Li x M y Q2, M is one or more of Ni, Co, Mn, Cu, Fe, Zn, Al and Cr, and Q is one or more of O, F, Cl, S, Se and N; And / or, the alkali metal A is Na and / or K; and / or, the compound containing alkali metal A is one or more of a metal salt containing alkali metal A, a base containing alkali metal A, and an oxide containing alkali metal A; And / or, the mass ratio of the alkali metal in the compound containing the alkali metal A to the lithium-containing layered oxide is (0.001-0.2):

1.

7. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 6, characterized in that: The salt containing alkali metal A is preferably sodium carbonate, sodium bicarbonate, potassium carbonate or potassium bicarbonate.

8. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 6, characterized in that: The base containing alkali metal A is sodium hydroxide or potassium hydroxide.

9. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 6, characterized in that: The oxide containing alkali metal A is sodium oxide or potassium oxide.

10. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 6, characterized in that: The mass ratio of the alkali metal in the compound containing the alkali metal A to the lithium-containing layered oxide is 0.005:1, 0.01:1, 0.02:1, 0.05:1 or 0.1:

1.

11. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 5, characterized in that: The high-valent metal with a valence of ≥3 is a transition metal with a valence of ≥3 and / or a main group metal with a valence of ≥3; And / or, the high-valent metal ion B containing a valence ≥ 3 n+ The metal salt is a high-valent metal ion B containing a valence ≥ 3 n+ Alkoxides and / or ammonium salts of And / or, the oxide containing a high-valent metal B with a valence ≥ 3 is tungsten oxide, molybdenum oxide, titanium oxide, zirconium oxide, niobium oxide, tantalum oxide, indium oxide, tin dioxide or antimony oxide; And / or, the high-valent metal ion B containing a valence ≥ 3 n+ The mass ratio of the high-valent metal with a valence ≥3 in the metal salt and / or the oxide containing the high-valent metal B with a valence ≥3 to the lithium-containing layered oxide is (0.001-0.2):

1.

12. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 11, wherein: The transition metal with a valence of ≥3 is one or more of Ti, Zr, Ru, Nb, Ta, Mo and W.

13. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 11, characterized in that: The main group metal with a valence of ≥3 is one or more of In, Sn and Sb.

14. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 11, characterized in that: The high-valent metal ion B containing a valence of ≥3 n+ The metal salt is tetrabutyl zirconate, tetrabutyl titanate, ammonium niobium oxalate, ammonium molybdate, ammonium tungstate, antimony nitrate or indium nitrate.

15. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 11, characterized in that: The high-valent metal ion B containing a valence of ≥3 n+ The mass ratio of the high-valent metal with a valence ≥ 3 in the metal salt and / or the oxide containing the high-valent metal B with a valence ≥ 3 to the lithium-containing layered oxide is 0.005:1, 0.007:1, 0.009:1, 0.01:1, 0.02:1 or 0.1:

1.

16. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 5, characterized in that: Method 1, in step (1), the annealing satisfies one or more of the following conditions: (1) The annealing temperature is 400-1000°C; (2) The annealing time is 4-24 hours; (3) The rate of heating to the annealing temperature is 1-10°C / min.

17. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 16, characterized in that: Method 1: In step (1), the annealing temperature is 500-800°C.

18. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 17, characterized in that: Method 1: In step (1), the annealing temperature is 550°C, 650°C or 700°C.

19. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 16, wherein: Method 1: In step (1), the annealing time is 6-24 h.

20. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 19, wherein: Method 1: In step (1), the annealing time is 10 h, 15 h or 20 h.

21. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 5, characterized in that: In step (2) of method 1 and / or method 2, the annealing satisfies one or more of the following conditions: (1) Method 1, in step (2), the annealing temperature is 200-1000°C; (2) Method 1, in step (2), the annealing time is 0.5-24 h; (3) Method 1, in step (2), the rate of heating to the annealing temperature is 1-10°C / min; (4) In method 2, the annealing temperature is 300-1000°C; (5) In method 2, the annealing time is 0.5-24 h; (6) In method 2, the rate of heating to the annealing temperature is 1-10°C / min.

22. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 21, characterized in that: Method 1: In step (2), the annealing temperature is 400-800°C.

23. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 22, characterized in that: Method 1: In step (2), the annealing temperature is 550°C, 650°C or 700°C.

24. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 21, wherein: Method 1: In step (2), the annealing time is 8-24 hours.

25. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 21, wherein: In the second method, the annealing temperature is 400-800°C.

26. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 25, characterized in that: In the second method, the annealing temperature is 550°C, 650°C or 700°C.

27. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 21, characterized in that: In method 2, the annealing time is 8-24 hours.

28. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 5, characterized in that: Method 1: In step (1), the mixture is further subjected to slight water mixing, solid phase mixing or liquid phase mixing before the annealing treatment; And / or, in step (2) of method one and / or method two, the mixture is further subjected to slight water mixing, solid phase mixing or liquid phase mixing before annealing.

29. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 28, wherein: The micro-water mixing comprises the following steps: stirring and evaporating the solution containing the mixture to dryness.

30. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 29, wherein: The solvent in the solution is one or more of deionized water, ethanol, acetone, DMF, ethylenediamine and triethylamine.

31. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 29, wherein: The amount of the solvent in the solution is sufficient to immerse the solid matter.

32. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 31, wherein: The ratio of the mass of the lithium-containing layered oxide to the volume of the solvent in the solution is (0.5-2) g / mL.

33. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 32, wherein: The ratio of the mass of the lithium-containing layered oxide to the volume of the solvent in the solution is 1 g / mL, 1.5 g / mL or 2 g / mL.

34. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 28, wherein: The solid phase mixing comprises the following steps: grinding the mixture.

35. The method for preparing a multi-metal co-doped coated positive electrode material according to claim 28, wherein: The liquid phase mixing comprises the following steps: fully stirring the solution containing the mixture at 15-200° C., and then performing solid-liquid separation and drying.

36. A multi-metal co-doped and coated positive electrode material prepared by the preparation method according to any one of claims 5 to 35.

37. Use of the multi-metal co-doped coated positive electrode material according to any one of claims 1 to 4 and claim 36 in a lithium-ion battery.

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