Surface-modified positive electrode material as well as preparation method and application thereof

Abstract

The invention discloses a surface-modified positive electrode material as well as a preparation method and application thereof. The surface modified positive electrode material is a lithium ion battery positive electrode material or a sodium ion battery positive electrode material, and a uniform polyanion interface bonded surface modified coating layer is formed on the surface of the positive electrode material through at least one of an oxygen-sulfur bond, an oxygen-phosphorus bond, an oxygen-silicon bond and an oxygen-boron bond. According to the surface-modified positive electrode material disclosed by the invention, the polyanion interface bonding layer coated on the surface is utilized, so that not only can the missing coordination oxygen on the surface of the positive electrode material be fixed, but also a shielding effect can be achieved at high voltage, and electrolyte can be effectively prevented from approaching the surface of the material and being subjected to oxygenolysis, thereby ensuring that the capacity of the material is stable at high voltage; and meanwhile, the problems of poor high-voltage cycling stability, poor structural stability, low specific capacity and poor rate of the positive electrode material are solved.

Description

Technical Field

[0001] The present application relates to the technical field of positive electrode materials, and in particular to a surface-modified positive electrode material and a preparation method and application thereof. Background Art

[0002] Lithium-ion batteries have become an integral part of our lives and are increasingly becoming larger and more advanced. This is driving higher demands on battery energy density, cycle life, and safety. Currently, the energy density and cycle life of lithium batteries are primarily limited by the cathode material. Currently, lithium cobalt oxide (LCO) and nickel-rich ternary materials are widely used as mainstream commercial cathode materials. However, in practice, the actual capacity of these materials remains far below their theoretical capacity. Therefore, the ultimate goal of current research on layered oxide cathodes, both in academia and industry, is to further increase their actual capacity through performance optimization, moving towards a theoretical capacity of 274 mAh / g. Increasing the charge voltage of LCO is the most effective way to increase its energy density. However, this comes at a significant cost, particularly in terms of cycle life and stability. Therefore, improving the high-voltage stability of LCO is a hot topic in this field. Surface modification is an effective approach to improving the high-voltage performance of LCO. Traditional surface modification processes usually include solid-solid interface reaction and solid-liquid interface reaction. The former method is difficult to ensure the uniformity of interface modification, while the latter method complicates the process and increases costs due to the introduction of liquid.

[0003] Therefore, how to simultaneously improve the cycle stability, structural stability, specific capacity, and rate performance of positive electrode materials remains the research focus and difficulty in the field of positive electrode material technology. Summary of the Invention

[0004] The purpose of this application is to provide a new surface-modified positive electrode material and its preparation method and application.

[0005] In order to achieve the above objectives, this application adopts the following technical solutions:

[0006] One aspect of the present application discloses a surface-modified positive electrode material, which is a lithium-ion battery positive electrode material or a sodium-ion battery positive electrode material, and the surface of the positive electrode material forms a uniform polyanion interfacially bonded surface modification coating layer through at least one of oxygen-sulfur bonds, oxygen-phosphorus bonds, oxygen-silicon bonds and oxygen-boron bonds.

[0007] It should be noted that the application forms a surface modification coating layer of at least one of the uniform and ultra-thin oxygen-sulfur bond, oxygen-phosphorus bond, oxygen-silicon bond and oxygen-boron bond on the surface of the positive electrode material, which can not only fix the surface coordination oxygen of the positive electrode material, but also shield the electrolyte from the surface of the material and prevent the oxidation and decomposition of the electrolyte, thereby ensuring the capacity stability of the material at high pressure, and solving the problems of poor high-pressure cycle stability, poor structure stability, low specific capacity and poor rate of the positive electrode material.

[0008] In an implementation manner of the application, the oxygen-sulfur bond is provided by at least one of sulfate, sulfite and sulfur oxide compound, the oxygen-phosphorus bond is provided by at least one of phosphate, pyrophosphate, phosphite and phosphorus oxide compound, the oxygen-silicon bond is provided by silicate, and the oxygen-boron bond is provided by borate.

[0009] In an implementation manner of the application, the lithium ion battery positive electrode material is at least one of spinel lithium manganate, cobalt-doped lithium manganate, nickel-cobalt-lithium manganate, lithium cobaltate, lithium nickelate, nickel-cobalt-aluminum lithium manganate, nickel-manganese lithium manganate and lithium-rich manganese-based material.

[0010] Preferably, the lithium ion battery positive electrode material is any one of spinel lithium manganate, nickel-cobalt-lithium manganate, lithium cobaltate, lithium nickelate, nickel-cobalt-aluminum lithium manganate, nickel-manganese lithium manganate and lithium-rich manganese-based material.

[0011] In an implementation manner of the application, the sodium ion battery positive electrode material is at least one of P2-type layered oxide, P3-type layered oxide, O3-type layered oxide, P2 / O3 composite layered oxide, spinel oxide and tunnel-type oxide.

[0012] Preferably, the sodium ion battery positive electrode material is any one of P2-type layered oxide, O3-type layered oxide, P2 / O3 composite layered oxide, spinel oxide and tunnel-type oxide.

[0013] In an implementation manner of the application, the thickness of the surface modification coating layer is 0.5-10 nm.

[0014] Another aspect of the application discloses a preparation method of the positive electrode material of the application, which comprises uniformly mixing the positive electrode material with a gas containing elements forming a polyanion interface bonding surface modification coating layer, or a solid capable of generating the gas, and then calcining; the calcining condition is calcining at 200-550℃ for 1-10 hours, and then heating to 600-900℃ for calcining for 1-10 hours, so that the elements in the gas and the oxygen on the surface of the positive electrode material form corresponding oxygen-sulfur bond, oxygen-phosphorus bond, oxygen-silicon bond and / or oxygen-boron bond, thereby forming a uniform polyanion interface bonding surface modification coating layer.

[0015] It should be noted that in the present application, the solid that can generate a gas containing elements that form a polyanion interfacial bonded surface modified coating layer, that is, it is itself a solid material, and can generate a gas containing elements that form a polyanion interfacial bonded surface modified coating layer during the calcination process, such as a gas containing sulfur, phosphorus, silicon and / or boron; the key to the present application is to use the sulfur-containing, phosphorus-containing, silicon-containing and / or boron-containing gas to carry out an in-situ gas-solid interface reaction on the surface of the solid positive electrode material, and to use the oxygen-sulfur bonds, oxygen-phosphorus bonds, oxygen-silicon bonds and / or oxygen-boron bonds generated by the reaction to form a uniform polyanion interfacial bonded surface modified coating layer. The preparation method of the present application is simple in process, easy to control, reproducible, low in cost, and the prepared positive electrode material has good comprehensive performance and broad practical prospects.

[0016] In one implementation of the present application, the molar ratio of the solid capable of generating gas containing elements forming a polyanion interface-bonded surface-modified coating layer to the positive electrode material is (0.01-0.2):1.

[0017] In one implementation of the present application, the sulfur-containing gas is sulfur dioxide.

[0018] In one implementation of the present application, the solid that generates the sulfur-containing gas is at least one of sulfur powder and ammonium sulfite.

[0019] In one implementation of the present application, the phosphorus-containing gas is phosphine.

[0020] In one implementation of the present application, the solid that generates the phosphorus-containing gas is red phosphorus.

[0021] Preferably, the silicon-containing gas is silane.

[0022] Preferably, the solid generating the silicon-containing gas is silazane.

[0023] Preferably, the boron-containing gas is borane.

[0024] Preferably, the solid generating the boron-containing gas is ammonia borane.

[0025] Another aspect of the present application discloses a positive electrode sheet containing the positive electrode material of the present application.

[0026] It should be noted that the key to the positive electrode plate of the present application is the use of the positive electrode material of the present application. As for other components, such as binders, current collectors, etc., reference can be made to the existing technology and no specific limitations are made here.

[0027] Another aspect of the present application discloses the use of the positive electrode material of the present application or the positive electrode plate of the present application in a lithium-ion battery or a sodium-ion battery.

[0028] Another aspect of the present application discloses a lithium-ion battery or a sodium-ion battery, which uses the positive electrode material or the positive electrode plate of the present application.

[0029] It should be noted that the lithium-ion battery or sodium-ion battery of the present application has the advantages of good high-voltage cycle stability, strong structural stability, high specific capacity, and good rate performance due to the use of the positive electrode material or the positive electrode plate of the present application.

[0030] Due to the adoption of the above technical solution, the beneficial effects of this application are:

[0031] The surface-modified positive electrode material of the present application utilizes a surface-coated polyanion interface bonding layer, which can not only fix the missing coordinated oxygen on the surface of the positive electrode material, but also play a shielding role under high voltage, effectively preventing the electrolyte from approaching the material surface and undergoing oxidative decomposition, thereby ensuring the capacity stability of the material under high voltage, and at the same time solving the problems of poor high-voltage cycle stability, poor structural stability, low specific capacity, and poor rate of the positive electrode material. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the X-ray powder diffraction pattern of the modified lithium cobalt oxide material in the embodiment of the present application;

[0033] Figure 2 1 is a scanning electron microscope image of the modified lithium cobalt oxide material and its element distribution diagram in the embodiment of the present application;

[0034] Figure 3 This is the cycle energy curve of a battery in which the positive electrode is made of lithium cobalt oxide material as the positive electrode active material and further assembled, and the cycle condition is: 1C. DETAILED DESCRIPTION

[0035] In response to the problems of poor high-voltage cycle stability, poor structural stability, low specific capacity and poor rate of existing positive electrode materials, the present application creatively discovered that by introducing sulfur, phosphorus, silicon and / or boron on the surface of the positive electrode material, and using sulfate, phosphate, pyrophosphate, silicate and / or borate to form a uniform polyanion interface-bonded surface modification coating layer, it can not only fix the missing coordinated oxygen on the surface of the positive electrode material oxide, but also play a shielding role at high voltage, effectively preventing the electrolyte from approaching the material surface and undergoing oxidative decomposition, thereby ensuring the material's capacity stability at high voltage, thereby solving the problems of poor high-voltage cycle stability, poor structural stability, low specific capacity and poor rate of the positive electrode material.

[0036] In one implementation of the present application, the positive electrode material of the present application is used to prepare a positive electrode and assembled into a lithium-ion battery. After testing, the lithium-ion battery has an initial discharge capacity of 220 mAh / g at a rate of 0.1C; at a rate of 1C, the initial discharge capacity reaches 202 mAh / g. Within the voltage range of 3.0-4.6 V, the capacity retention rate is 81% after 300 cycles.

[0037] The present invention will be further described in detail below by means of specific embodiments in conjunction with the accompanying drawings. The following examples are only provided to further illustrate the present application and should not be construed as limiting the present application.

[0038] Example 1

[0039] In this example, the surface of the lithium cobalt oxide positive electrode material is modified. The specific method includes the following steps:

[0040] 1.96g of lithium cobalt oxide powder and 0.0128g of sulfur powder were uniformly mixed to form a precursor. The molar ratio of sulfur powder to lithium cobalt oxide in the precursor was 0.02:1. The precursor was heated to 550°C and sintered for 2 hours, then heated to 850°C and sintered for 4 hours. The resulting cathode material for a lithium-ion battery was then cooled to room temperature.

[0041] Example 2

[0042] In this example, the surface of the lithium cobalt oxide positive electrode material is modified. The specific method includes the following steps:

[0043] A precursor was prepared by uniformly mixing 1.96 g of lithium cobalt oxide powder with 0.032 g of sulfur powder. The molar ratio of sulfur powder to lithium cobalt oxide in the precursor was 0.05:1. The precursor was heated to 550°C and sintered for 2 hours, then heated to 850°C and sintered for 4 hours. The resulting cathode material for a lithium-ion battery was then cooled to room temperature.

[0044] Example 3

[0045] In this example, the surface of the lithium cobalt oxide positive electrode material is modified. The specific method includes the following steps:

[0046] 1.96g of lithium cobalt oxide powder and 0.064g of sulfur powder were uniformly mixed to form a precursor. The molar ratio of sulfur powder to lithium cobalt oxide in the precursor was 0.1:1. The precursor was heated to 550°C and sintered for 2 hours, then heated to 850°C and sintered for 4 hours. The resulting cathode material for a lithium-ion battery was then cooled to room temperature.

[0047] Example 4

[0048] In this example, the surface of the lithium cobalt oxide positive electrode material is modified. The specific method includes the following steps:

[0049] A precursor was prepared by uniformly mixing 1.96 g of lithium cobalt oxide powder with 0.032 g of sulfur powder. The molar ratio of sulfur powder to lithium cobalt oxide in the precursor was 0.05:1. The precursor was heated to 550°C and sintered for 5 hours, then heated to 850°C and sintered for 4 hours. The resulting cathode material for a lithium-ion battery was then cooled to room temperature.

[0050] Example 5

[0051] In this example, the surface of the lithium cobalt oxide positive electrode material is modified. The specific method includes the following steps:

[0052] A precursor was prepared by uniformly mixing 1.96 g of lithium cobalt oxide powder with 0.032 g of sulfur powder. The molar ratio of sulfur powder to lithium cobalt oxide in the precursor was 0.05:1. The precursor was heated to 550°C and sintered for 2 hours, then heated to 850°C and sintered for 2 hours. The resulting cathode material for a lithium-ion battery was then cooled to room temperature.

[0053] Example 6

[0054] In this example, the surface of the lithium cobalt oxide positive electrode material is modified. The specific method includes the following steps:

[0055] 1.96g of lithium cobalt oxide powder and 0.032g of sulfur powder were uniformly mixed to form a precursor. The molar ratio of sulfur powder to lithium cobalt oxide in the precursor was 0.05:1. The precursor was heated to 400°C and sintered for 2 hours, then heated to 850°C and sintered for 4 hours. The resulting cathode material for a lithium-ion battery was then cooled to room temperature.

[0056] Example 7

[0057] In this example, the surface of the lithium cobalt oxide positive electrode material is modified. The specific method includes the following steps:

[0058] 1.96g of lithium cobalt oxide powder and 0.032g of sulfur powder were uniformly mixed to form a precursor. The molar ratio of sulfur powder to lithium cobalt oxide in the precursor was 0.05:1. The precursor was heated to 550°C and sintered for 2 hours, then heated to 700°C and sintered for 4 hours. The resulting cathode material for a lithium-ion battery was then cooled to room temperature.

[0059] Example 8

[0060] In this example, the surface of the lithium cobalt oxide positive electrode material is modified. The specific method includes the following steps:

[0061] 1.96g of lithium cobalt oxide powder and 0.01278g of red phosphorus were uniformly mixed to form a precursor. The molar ratio of red phosphorus to lithium cobalt oxide in the precursor was 0.02:1. The precursor was heated to 550°C and sintered for 2 hours, then heated to 850°C and sintered for 4 hours. The resulting cathode material for a lithium-ion battery was then cooled to room temperature.

[0062] Example 9

[0063] In this example, the surface of the lithium cobalt oxide positive electrode material is modified. The specific method includes the following steps:

[0064] A precursor was prepared by uniformly mixing 1.96g of lithium cobalt oxide powder with 0.00639g of red phosphorus and 0.0128g of sulfur powder. The molar ratio of red phosphorus, sulfur powder, and lithium cobalt oxide in the precursor was 0.01:0.02:1. The precursor was heated to 550°C and sintered for 2h, then heated to 850°C and sintered for 4h. The resulting cathode material for a lithium-ion battery was then cooled to room temperature.

[0065] Example 10

[0066] In this example, the surface of the lithium cobalt oxide positive electrode material is modified. The specific method includes the following steps:

[0067] 1.96g of lithium cobalt oxide powder and 0.045g of polysilazane were uniformly mixed to form a precursor. The molar ratio of polysilazane to lithium cobalt oxide in the precursor was 0.05:1. The precursor was heated to 550°C and sintered for 2 hours, then heated to 700°C and sintered for 4 hours. The resulting cathode material for a lithium-ion battery was then cooled to room temperature.

[0068] Example 11

[0069] In this example, the surface of the lithium cobalt oxide positive electrode material is modified. The specific method includes the following steps:

[0070] 1.96g of lithium cobalt oxide powder and 0.031g of ammonia borane were uniformly mixed to form a precursor. The molar ratio of ammonia borane to lithium cobalt oxide in the precursor was 0.05:1. The precursor was heated to 550°C and sintered for 2 hours, then heated to 700°C and sintered for 4 hours. The cathode material for the lithium-ion battery was obtained.

[0071] Example 12

[0072] In this example, the surface of the lithium nickel cobalt aluminum oxide positive electrode material is modified. The specific method includes the following steps:

[0073] A precursor was prepared by uniformly mixing 1.96g of lithium nickel cobalt aluminum oxide powder with 0.032g of sulfur powder. The molar ratio of sulfur powder to lithium nickel cobalt aluminum oxide in the precursor was 0.05:1. The precursor was heated to 550°C and sintered in an oxygen atmosphere for 2 hours, then to 750°C and sintered for 4 hours. The precursor was then cooled to room temperature to obtain the lithium-ion battery cathode material of this example.

[0074] Example 13

[0075] In this example, the surface of the lithium manganese oxide positive electrode material is modified, and the specific method includes the following steps:

[0076] 3.616g of lithium manganate powder and 0.032g of sulfur powder were uniformly mixed to form a precursor. The molar ratio of sulfur powder to lithium manganate in the precursor was 0.05:1. The precursor was heated to 550°C and sintered for 2 hours, then heated to 750°C and sintered for 4 hours. The precursor was then cooled to room temperature to obtain the lithium-ion battery positive electrode material of this example.

[0077] Example 14

[0078] In this example, the surface of the lithium nickel cobalt manganese oxide positive electrode material is modified. The specific method includes the following steps:

[0079] A precursor was prepared by uniformly mixing 1.96 g of lithium nickel cobalt manganese oxide powder with 0.032 g of sulfur powder. The molar ratio of sulfur powder to lithium nickel cobalt manganese oxide in the precursor was 0.05:1. The precursor was heated to 550°C and sintered for 2 hours, then heated to 750°C and sintered for 4 hours. The resulting cathode material for a lithium-ion battery was then cooled to room temperature.

[0080] Example 15

[0081] In this example, the surface of the lithium-rich manganese-based positive electrode material is modified. The specific method includes the following steps:

[0082] A precursor was prepared by uniformly mixing 1.96 g of lithium-rich manganese-based material powder with 0.032 g of sulfur powder. The molar ratio of sulfur powder to lithium-rich manganese-based material in the precursor was 0.05:1. The precursor was heated to 550°C and sintered for 2 hours, then heated to 750°C and sintered for 4 hours. The resulting cathode material for a lithium-ion battery was then cooled to room temperature.

[0083] Example 16

[0084] In this case, P2 type Na 0.66 Ni 0.33 Mn 0.66 The surface of the O2 sodium cathode material is modified, and the specific method includes the following steps:

[0085] 2.069g Na 0.66 Ni 0.33 Mn 0.66 O2 sodium cathode powder and 0.032g of sulfur powder were uniformly mixed to form a precursor. The molar ratio of sulfur powder to sodium cathode powder in the precursor was 0.05:1. In an oxygen atmosphere, the precursor was heated to 550°C and sintered for 2 hours, then heated to 750°C and sintered for 4 hours. The precursor was then cooled to room temperature to obtain the sodium-ion battery cathode material of this example.

[0086] Example 17

[0087] In this case, O3 type NaNi 0.5 Mn 0.5 The surface of the O2 sodium cathode material is modified, and the specific method includes the following steps:

[0088] 2.236g NaNi 0.5 Mn 0.5 O2 sodium cathode powder and 0.032g of sulfur powder were uniformly mixed to form a precursor. The molar ratio of sulfur powder to sodium cathode powder in the precursor was 0.05:1. The precursor was heated to 550°C and sintered for 2 hours, then heated to 750°C and sintered for 4 hours. The precursor was then cooled to room temperature to obtain the sodium-ion battery cathode material of this example.

[0089] Comparative Example 1

[0090] 1.96 g of lithium cobalt oxide powder was heated to 550° C. and sintered for 2 h, then heated to 850° C. and sintered for 4 h, and then cooled to room temperature to obtain a lithium-ion battery positive electrode material.

[0091] X-ray diffraction analysis was performed on the lithium ion battery positive electrode materials and sodium ion battery positive electrode materials prepared in Examples 1-17 and Comparative Example 1. Some of the results are as follows: Figure 1 shown. Figure 1 This is the X-ray powder diffraction pattern of the modified lithium cobalt oxide material obtained in Example 2.

[0092] X-ray diffraction results show that the samples treated with SO2 gas, red phosphorus, silazane and / or ammonia borane are still pure-phase cathode materials, and no impurity phases are detected; Figure 1 As shown in the figure, the sample is still pure phase layered lithium cobalt oxide after SO2 gas treatment.

[0093] The lithium ion battery positive electrode materials and sodium ion battery positive electrode materials prepared in Examples 1-17 and Comparative Example 1 were observed by scanning electron microscopy. Some of the results are as follows: Figure 2 shown. Figure 2 2 are the scanning electron microscope images and element distribution diagrams of the modified lithium cobalt oxide material obtained in Example 2.

[0094] Scanning electron microscopy results show that the cathode material particles after treatment with SO2 gas, red phosphorus, silazane and / or ammonia borane are single crystal particles with relatively smooth particle surfaces and no obvious coating. However, the element distribution map shows that sulfur, phosphorus, silicon and / or boron are evenly distributed on the particle surface, indicating that the coating layer formed is thin and uniform. Figure 2 As shown in FIG, the lithium cobalt oxide material particles after SO2 gas treatment are single crystal particles with an average particle size of about 5 microns. The particle surface is relatively smooth and no coating can be seen. However, the element distribution map shows that sulfur is evenly distributed on the particle surface, indicating that the coating layer is thin and uniform.

[0095] The lithium-ion battery positive electrode materials prepared in Examples 1-15 and Comparative Example 1 were assembled into experimental button-type lithium-ion batteries in an argon-protected glove box (wherein the negative electrode was metallic lithium, the electrolyte solvent was EC:DMC:EMC=1:1:1, the solute was LiPF6, and the separator was Celgard 2316). The sodium-based positive electrode materials prepared in Examples 16 and 17 were assembled into experimental button-type sodium-ion batteries in an argon-protected glove box (wherein the negative electrode was metallic sodium, the electrolyte solvent was acrylate and 5% fluoroethylene carbonate additive, the solute was NaClO4, and the separator was a glass fiber membrane). The specific capacity and cycle performance of the above-mentioned lithium / sodium ion batteries were tested, and the test results are shown in Table 1.

[0096] Table 1 Performance test of lithium-ion battery and sodium-ion battery

[0097] project Specific capacity / mA·h / g(1C) Capacity retention rate (300 times) Example 1 195 76％ Example 2 202 81％ Example 3 198 78％ Example 4 189 74％ Example 5 197 76％ Example 6 199 79％ Example 7 196 70％ Example 8 195 72％ Example 9 198 75％ Example 10 197 78％ Example 11 199 74％ Example 12 176 85％ Example 13 118 90％ Example 14 181 83％ Example 15 263 77％ Example 16 110 65％ Example 17 80 75％ Comparative Example 1 193 18％

[0098] The results in Table 1 show that SO2 gas, red phosphorus, silazane and / or ammonia borane treatment can optimize the cycle performance of positive electrode materials such as lithium cobalt oxide. The best cycle stability can be obtained under the treatment conditions of Example 2, while the cycle stability of the sample of Comparative Example 1 that only underwent subsequent secondary heat treatment is much lower than that of the material with the introduction of SO2 gas.

[0099] The battery cycle performance was tested, and some of the results are as follows: Figure 3 shown. Figure 3 This is the cycling energy curve of a battery in which the lithium cobalt oxide material obtained in Example 2 and Comparative Example 1 is used as the positive electrode active material to prepare a positive electrode and further assembled, and the cycling condition is: 1C.

[0100] The results of the cycle performance test show that the introduction of SO2 gas, red phosphorus, silazane and / or ammonia borane during the heat treatment of positive electrode materials such as lithium cobalt oxide can greatly improve the cycle stability.

[0101] The above examples are used to illustrate the present invention, which are only used to help understand the present invention and are not intended to limit the present invention. Those skilled in the art can make several simple deductions, modifications or substitutions based on the concept of the present invention.

Claims

1. A surface-modified positive electrode material, wherein the positive electrode material is a lithium-ion battery positive electrode material or a sodium-ion battery positive electrode material, characterized in that: The surface of the positive electrode material forms a surface modified coating layer with uniform polyanion interface bonding through at least one of oxygen-sulfur bond, oxygen-phosphorus bond, oxygen-silicon bond and oxygen-boron bond.

2. The positive electrode material according to claim 1, characterized in that: The oxygen-sulfur bond is provided by at least one of sulfate, sulfite and sulfur oxide, the oxygen-phosphorus bond is provided by at least one of phosphate, pyrophosphate, phosphite and phosphorus oxide, the oxygen-silicon bond is provided by silicate, and the oxygen-boron bond is provided by borate.

3. The positive electrode material according to claim 1, wherein: The positive electrode material of the lithium-ion battery is at least one of spinel lithium manganate, cobalt-doped lithium manganate, nickel cobalt lithium manganate, lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt aluminum oxide, lithium nickel manganate and lithium-rich manganese-based materials; Preferably, the positive electrode material of the lithium-ion battery is any one of spinel lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt aluminum oxide, lithium nickel manganese oxide and lithium-rich manganese-based materials.

4. The positive electrode material according to claim 1, characterized in that: The sodium ion battery positive electrode material is at least one of a P2-type layered oxide, a P3-type layered oxide, an O3-type layered oxide, a P2 / O3 composite layered oxide, a spinel-type oxide, and a tunnel-type oxide; Preferably, the sodium ion battery positive electrode material is any one of a P2-type layered oxide, an O3-type layered oxide, a P2 / O3 composite layered oxide, a spinel-type oxide and a tunnel-type oxide.

5. The positive electrode material according to any one of claims 1 to 4, characterized in that: The thickness of the surface modified coating layer is 0.5-10 nm.

6. The method for preparing the positive electrode material according to any one of claims 1 to 5, characterized in that: The method comprises uniformly mixing a positive electrode material with a gas containing an element that forms a polyanion interface-bonded surface modified coating layer, or a solid that can generate the gas, and then calcining the mixture; the calcination conditions are as follows: calcining at 200-550° C. for 1-10 hours, then heating to 600-900° C. for 1-10 hours, so that the element forms corresponding oxygen-sulfur bonds, oxygen-phosphorus bonds, oxygen-silicon bonds and / or oxygen-boron bonds with oxygen on the surface of the positive electrode material, thereby forming a uniform polyanion interface-bonded surface modified coating layer.

7. The preparation method according to claim 6, characterized in that: The molar ratio of the solid capable of generating the gas to the positive electrode material is (0.01-0.2):1; Preferably, the sulfur-containing gas is sulfur dioxide; Preferably, the solid that generates sulfur-containing gas is at least one of sulfur powder and ammonium sulfite; Preferably, the phosphorus-containing gas is phosphine; Preferably, the solid that generates the phosphorus-containing gas is red phosphorus; Preferably, the silicon-containing gas is silane; Preferably, the solid generating the silicon-containing gas is silazane; Preferably, the boron-containing gas is borane; Preferably, the solid generating the boron-containing gas is ammonia borane.

8. A positive electrode plate, characterized in that: Contains the positive electrode material according to any one of claims 1 to 5.

9. Use of the positive electrode material according to any one of claims 1 to 5, or the positive electrode sheet according to claim 8, in a lithium-ion battery or a sodium-ion battery.

10. A lithium-ion battery or a sodium-ion battery, characterized in that: The positive electrode material according to any one of claims 1 to 5 or the positive electrode sheet according to claim 8 is used.

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