Composite high-voltage lithium ion battery positive electrode material, preparation method thereof and battery

Abstract

The invention discloses a composite high-voltage lithium ion battery positive electrode material, a preparation method thereof and a battery, and belongs to the technical field of battery materials. The lithium ion battery positive electrode material comprises a positive electrode active material, a coating layer and a transition layer, the coating layer is a niobium-based composite fast charging material, and the positive electrode active material is coated with the niobium-based composite fast charging material; the positive electrode active material and the niobium-based composite quick charge material form a transition layer in the coating process; the positive electrode active material comprises lithium-containing compound particles with a chemical formula of LixMyOz, 0.8 < = x < = 2.2, 0.8 < = y < = 2.2, and 1.8 < = z < = 4.2; the niobium-based composite negative electrode material coats the surface of the positive electrode active material, so that the rate capability of the positive electrode active material can be remarkably improved, the niobium element of the niobium-based composite quick charge material can be partially diffused into the surface of the positive electrode active material, and the surface of the positive electrode active material is stabilized; the material can still maintain excellent electrochemical performance under high-rate charging and low-temperature charging, and has high interface stability at high temperature.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery materials, and more particularly to a composite high-voltage lithium ion battery positive electrode material, a preparation method thereof and a battery. BACKGROUND

[0002] Lithium ion secondary batteries have become the ideal power source for new generation electric vehicles due to their excellent performance. At present, the main positive electrode materials of lithium ion secondary batteries that can be commercialized on a large scale are mainly embedded reaction electrode structure systems, which can be roughly divided into three categories: layered materials (represented by lithium cobaltate), olivine-type materials (represented by lithium iron phosphate) and spinel structure materials (represented by lithium manganate). In recent years, the demand for fast charging and discharging of electric vehicles has increased significantly. In order to improve the fast charging performance, one can start from the design and structure of the battery, and the other can optimize the material structure design.

[0003] Currently, fast ion conductors are commonly used to coat positive electrode materials, but this method has limited improvement in rate performance. In view of this, we propose a composite high-voltage lithium ion battery positive electrode material, a preparation method thereof and a battery. SUMMARY

[0004] The present application aims to provide a composite high-voltage lithium ion battery positive electrode material, a preparation method thereof and a battery to solve the problems raised in the background art. The present application aims to provide a positive electrode active material with excellent rate performance, which still maintains relatively optimal electrochemical performance under high-rate charging and low-temperature charging, and has high interface stability at high temperature.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0006] A composite high-voltage lithium ion battery positive electrode material, comprising a positive electrode active material, a coating layer and a transition layer, the coating layer being a niobium-based composite fast charging material, and the niobium-based composite fast charging material being coated on the positive electrode active material; wherein the positive electrode active material serves as an inner core layer.

[0007] The positive electrode active material and the niobium-based composite fast charging material form a transition layer during the coating process;

[0008] The positive electrode active material comprises lithium-containing compound particles with a chemical formula of Li x M y O z , wherein 0.8≤x≤2.2, 0.8≤y≤2.2 and 1.8≤z≤4.2; M is at least one of Na, K, Al, Mg, Zn, Ni, Mn, Fe, Co, Ti, Y, Sc, Ru, Cu, Mo, Ge, W, Zr, Ca, Nb, Ta, P, S, F, B, Si, Ba, Pb, V, In, Ga, Sb, Bi and Sr.

[0009] Preferably, Li x M y O z Includes the following positive electrode active materials: LiCoO2, LiMnO2, LiNiO2, LiVO2, LiNi 1 / 3Co 1 / 3 Mn 1 / 3 O2、LiMn2O4、Li(Ni 0.5 Mn 1.5 )O4, Li2FeSiO4, Li2MnSiO4, and doped and coated derivatives of the foregoing positive electrode active materials.

[0010] Preferably, the positive electrode active material is LiNi with a spinel structure 0.5-k Mn 1.5-m M p O 4-n , wherein M is selected from one or more doping elements of Mg, Fe, Co, Y, Sc, Ru, Cu, Mo, Ce, W, Zr, Ca, P, S, F, B, Si and Sr, -0.2≤k≤0.2, -0.2≤m≤0.2, 0≤p≤0.1, and -0.2≤n≤0.2.

[0011] Preferably, the niobium-based composite fast-charging material is: NiM a Nb 2+b O6、TiM a Nb 2+b O7、Ti2M a Nb 10+b O 29 、M c Nb d O e and Ti2M a Nb 24+b O 62 wherein, 0≤a≤0.2, -0.4≤b≤0.4, 0<c≤1, 0<d≤1, 0<e≤1, and M is at least one of Na, K, Al, Mg, Zn, Ni, Mn, Fe, Co, Ti, Y, Sc, Ru, Cu, Mo, Ge, W, Zr, Ca, Nb, Ta, P, V, S, F, B, Si, Ba, Pb, In, Ga, Sb, Si, Bi, and Sr.

[0012] Preferably, the niobium-based composite fast-charging material is: Ni 0.166 Nb 0.333 O(NiNb2O6), Ti 0.142 Nb 0.286 O(TiNb2O7), Ti 0.069 Nb0.345 O(Ti2Ni 10 O 29 ),Mg 0.023 Nb 0.391 O(Mg2Nb 34 O 87 ), Zn 0.023 Nb 0.391 O(Zn2Nb 34 O 87 )、Mo 0.030 Nb 0.364 O(MoNb 12 O 33 ), Ga 0.008 Nb 0.395 O(GaNb 49 O 124 ), Zr 0.16 1Nb 0.387 (ZrNb 24 O 62 ) and Ti 0.032 Nb 0.387 O(Ti2Nb 24 O 62 ) and their doped and coated derivatives.

[0013] Preferably, the thickness of the coating layer is 2 nm to 2000 nm; the thickness of the niobium-based composite fast-charging material phase is 2 nm to 2000 nm; and the particle size of the positive electrode active material is 0.1 μm to 30 μm.

[0014] Preferably, a method for preparing a composite high-voltage lithium-ion battery positive electrode material is used to prepare the above-mentioned composite high-voltage lithium-ion battery positive electrode material, comprising the following steps:

[0015] uniformly mixing the raw material of the positive electrode active material with the niobium-based fast charging material or its precursor to obtain a mixture;

[0016] The obtained mixture is sintered in an atmosphere containing oxygen to prepare a positive electrode active material.

[0017] Preferably, the median particle size D50 of the positive electrode active material is 2 to 20 μm, and the median particle size D50 of the niobium-based fast charging material is 2 to 2000 nm; the sintering heating and cooling rate is 0.5 to 8° C. / min, and the mixture is sintered at 400-1200° C. for 1-10 hours.

[0018] Preferably, a lithium battery positive electrode comprises a current collector on which the above-mentioned composite high-voltage lithium-ion battery positive electrode material is loaded.

[0019] Preferably, a lithium battery comprises at least two of a separator, an electrolyte, a negative electrode, a lithium supplement agent, and a composite high-voltage lithium ion battery positive electrode material comprising the above-mentioned composite high-voltage lithium ion battery positive electrode material.

[0020] Compared with the prior art, the present application has the following advantages:

[0021] (1) In the past, niobium-based materials have been used as negative electrode materials. The present application can significantly improve the rate performance of positive electrode active materials by coating niobium-based composite negative electrode materials on the surface of positive electrode active materials. At the same time, the niobium element of the niobium-based composite fast-charging material will partially diffuse into the surface of the positive electrode active material, stabilizing the surface of the positive electrode active material. This new material can further improve the fast-charging and low-temperature performance of the material while maintaining the original cycle stability of the material. It still maintains excellent electrochemical performance under high-rate charging and low-temperature charging, and has high interface stability at high temperatures.

[0022] Especially in a battery system where the negative electrode is a niobium-based negative electrode, during the cycle process of the entire battery, niobium of the negative electrode will drift to the positive electrode and deposit on the surface of the positive electrode. Therefore, if the positive electrode surface itself has niobium elements, the interface film generated on the positive electrode surface can be more stable and can better resist the influence of the positive and negative electrode cross effect.

[0023] (2) The preparation method of the lithium battery positive electrode active material provided by the present application has simple process steps and can quickly and conveniently prepare a positive electrode active material coated with a niobium-based fast-charging material. The method can improve the low-temperature electrochemical performance and rate performance of the positive electrode active material while maintaining the stability of the surface structure. It has important significance for the all-weather application and fast-charging application of lithium batteries. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all.

[0025] Embodiment 1:

[0026] A composite high-voltage lithium ion battery positive electrode material comprises a positive electrode active material, a coating layer, and a transition layer. The coating layer is a niobium-based composite fast-charging material, and the niobium-based composite fast-charging material is coated on the positive electrode active material.

[0027] The positive electrode active material and the niobium-based composite fast-charging material form a transition layer during the coating process. The coating layer can be uniformly distributed, unevenly distributed, gradiently distributed, or island-shaped distributed on the surface of the core positive electrode active material.

[0028] During the coating process, the niobium element of the niobium-based composite fast-charging material will partially diffuse into the surface of the positive active material, stabilizing the surface of the positive active material. This new type of material can further improve the fast-charging and low-temperature performance of the material while maintaining the original cycle stability of the material. It still maintains relatively optimal electrochemical performance under high-rate charging and low-temperature charging, and has high interface stability at high temperatures. Especially in the battery system where the negative electrode is a niobium-based negative electrode, during the cycle process of the entire battery, the niobium of the negative electrode will drift to the positive electrode and deposit on the surface of the positive electrode. Therefore, if the positive electrode surface itself has niobium elements, the interface film generated on the positive electrode surface can be more stable and can better resist the influence of the positive and negative cross effects.

[0029] The positive active material includes lithium-containing compound particles of the chemical formula Li x M y O z , wherein 0.8≤x≤2.2, 0.8≤y≤2.2, 1.8≤z≤4.2; M is at least one of Na, K, Al, Mg, Zn, Ni, Mn, Fe, Co, Ti, Y, Sc, Ru, Cu, Mo, Ge, W, Zr, Ca, Nb, Ta, P, S, F, B, Si, Ba, Pb, V, In, Ga, Sb, Bi, and Sr.

[0030] In this application, Li x M y O z includes the following positive active materials: LiCoO2, LiMnO2, LiNiO2, LiVO2, LiNi 1 / 3Co 1 / 3 Mn 1 / 3 O2, LiMn2O4, Li(Ni 0.5 Mn 1.5 )O4, Li2FeSiO4, Li2MnSiO4, and doped and coated derivatives of the aforementioned positive active materials.

[0031] In this application, the positive active material is LiNi 0.5-k Mn 1.5-m M p O 4-n , wherein M is selected from one or more doping elements of Mg, Fe, Co, Y, Sc, Ru, Cu, Mo, Ce, W, Zr, Ca, P, S, F, B, Si, and Sr, -0.2≤k≤0.2, -0.2≤m≤0.2, 0≤p≤0.1, -0.2≤n≤0.2.

[0032] wherein the chemical formula is LiNi 0.5-k Mn 1.5-m M p O 4-nThe spinel structure of the lithium-containing compound can include a rock-salt phase formed by at least one element of Ni, Mn, Nb, M occupying the spinel structure vacancies, the occupying element being located at the 16c or 8a position of the spinel phase; the proportion of the formed rock-salt phase to the original spinel phase is less than 10%.

[0033] In the present application, the niobium-based composite fast-charging material is: Ni a Nb 2+b O6, TiM a Nb 2+b O7, Ti2M a Nb 10+b O 29 , M c Nb d O e and Ti2M a Nb 24+b O 62 , at least one of which; wherein 0≤a≤0.2, -0.4≤b≤0.4, 0

[0034] The niobium-based composite fast-charging material can be specifically: Ni 0.166 Nb 0.333 O(NiNb2O6), Ti 0.142 Nb 0.286 O(TiNb2O7), Ti 0.069 Nb 0.345 O(Ti2Ni 10 O 29 ), Mg 0.023 Nb 0.391 O(Mg2Nb 34 O 87 ), Zn 0.023 Nb 0.391 O(Zn2Nb 34 O 87 ), Mo 0.030 Nb 0.364 O(MoNb 12 O 33 ), Ga 0.008 Nb 0.395 O(GaNb 49 O 124 ), Zr 0.16 1Nb 0.387 (ZrNb 24 O62 ) and Ti 0.032 Nb 0.387 O (Ti2Nb 24 O 62 and doped and coated derivatives thereof.

[0035] In the present application, the thickness of the coating layer is 2nm-2000nm; the thickness of the niobium-based composite fast-charging material phase is 2nm-2000nm; and the particle size of the positive electrode active material is 0.1-30μm.

[0036] A preparation method of a composite high-voltage lithium ion battery positive electrode material, for preparing the composite high-voltage lithium ion battery positive electrode material, comprising the following steps:

[0037] Step 1: uniformly mixing raw materials of a positive electrode active material with a niobium-based fast-charging material or a precursor thereof to obtain a mixture;

[0038] Step 2: sintering the obtained mixture in an atmosphere containing oxygen to obtain the positive electrode active material;

[0039] In step 1, the median particle size D50 of the positive electrode active material is 2-20um, and the median particle size D50 of the niobium-based fast-charging material is 2-2000nm;

[0040] In step 2, the temperature rising and falling rate of sintering is 0.5-8℃ / min, and the mixture is sintered at 400-1200℃ for 1-10h.

[0041] The preparation method mixes lithium compound particles with coating substances or precursors thereof, obtains the positive electrode material finished product through high-temperature sintering, crushing and screening, and improves the rate performance and high-temperature cycle stability of the positive electrode material. The technical scheme provided by the present application is also suitable for industrial production.

[0042] Example 2:

[0043] A lithium battery positive electrode, comprising a current collector, and the current collector is loaded with the composite high-voltage lithium ion battery positive electrode material.

[0044] A lithium battery, comprising at least two of a separator, an electrolyte, a negative electrode, a lithium supplement agent and the composite high-voltage lithium ion battery positive electrode material.

[0045] The lithium battery provided by the application, wherein the electrolyte can be a common liquid electrolyte or a solid electrolyte. The liquid electrolyte can be composed of an organic solvent and a lithium salt, the organic solvent can be selected from one or more of the following: methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, ethylene sulfite, propylene sulfite, diethyl sulfite, gamma-butyrolactone, dimethyl sulfoxide, ethyl acetate, methyl acetate, tetrahydrofuran, dimethyl methane, 2-dimethyl tetrahydrofuran, 1,2-dimethyl ethane, 1,3-dioxolane and diethylene glycol dimethyl ether; the lithium salt can be selected from one or more of the following: lithium perchlorate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis-trifluoromethyl sulfonylimide, lithium trifluoromethyl sulfonate, lithium difluoro oxalate borate, lithium bis-oxalate borate. The liquid electrolyte can further contain an electrolyte additive containing elements such as N, P, Si, B, F, S, or an electrolyte additive containing a carbonyl group or a benzene ring. The solid electrolyte can be Li 3x La 2 / 3-x TiO3(0≤x≤2 / 3) of perovskite; NaSICON with general formula Li x M y (PO4)3(1≤x≤3, 1≤y≤2, M is selected from one or more of Ge, Al, Ti, Ga, Zr, Fe and Nb); ceramic oxide with garnet structure; sulfide with composition Li2S-P2S5 and Li2S-Ge2S5; and solid electrolyte with other crystal or amorphous structure, such as Li3N, LISICON (Lithium Super Ionic Conductor), Thio-LISICON (Li 3.25 Ge 0.25 P 0.75 S4), LiPON, PEO and other oxide-based, sulfide-based, phosphate-based and polymer-based materials, wherein the ceramic oxide with garnet structure is, for example, oxide Li5La3M2O 12 (M=Nb or Ta), Li6ALa2M2O 12 (A=Ca, Sr or Ba; M=Nb or Ta), Li 5.5 La3M 1.75 B 0.25 O 12 (M=Nb or Ta; B=In or Zr), Li7La3Zr2O 12 and Li 7.06 M3Y 0.06 Zr 1.94 O 12 (M=La, Nb or Ta).

[0046] When a solid electrolyte is used, the particle size of the solid electrolyte particles can be 0.1 to 20 μm, preferably 0.5 to 10 μm.

[0047] The lithium battery provided by the present application, wherein the lithium supplementing agent is a lithium-containing substance, such as lithium powder, lithium ribbon, lithium rod, organic lithium, inorganic lithium, including but not limited to Li6CoO4, Li2NiO2, Li2S, Li5FeO4, LiF, Li2O, Li2O2, Li3N and the like.

[0048] The lithium battery provided by the present application, wherein the negative electrode comprises an active material capable of occluding and releasing lithium ions, such as one of graphite, Li metal, a metal capable of forming an alloy with Li metal, and a mixture or alloy thereof. As the metal capable of forming an alloy with Li (or referred to as "alloying material"), one or more of aluminum, silicon, tin, bismuth and indium is preferred.

[0049] Example 3: Performance test;

[0050] Sample 1: 100 g of lithium nickel manganese oxide material (comparative sample 1) and 2 g of nano TiNb2O7 were weighed and put into a ball mill jar, and grinded for 60 min. Then the grinded powder was placed in a box furnace and calcined at 700°C for 5 h to obtain sample 1, spinel lithium nickel manganese oxide anode material coated with TiNb2O7.

[0051] Sample 2: 100 g of lithium nickel manganese oxide material (comparative sample 1) and 1.5 g of nano NiNb2O6 were mixed uniformly, and then the mixture was placed in a box furnace and calcined at 650°C for 8 h to obtain sample 2, spinel lithium nickel manganese oxide anode material coated with NiNb2O6.

[0052] Sample 3: 100 g of lithium cobalt oxide material (comparative sample 2) was added to a mixture of 3.6 g of ammonium niobium oxalate, 0.47 g of TiO2, 0.024 g of zinc acetate, 100 g of deionized water and 0.2 g of hydroxymethyl cellulose, and the mixture was stirred and evaporated to dryness at 100°C. The obtained powder was dried and grinded, and then sintered at 900°C for 5 h in an atmosphere containing 18% oxygen to obtain sample 3, lithium cobalt oxide anode material coated with Zn0.02Ti0.98Nb2O7.

[0053] Electrochemical performance test:

[0054] First, the anode active materials prepared from samples 1-3 and comparative samples 1-2 were prepared into button cells according to the following method.

[0055] 1) Preparation of positive electrode sheet

[0056] The positive electrode active material, carbon black as a conductive additive and polyvinylidene fluoride (PVDF) as a binder were dispersed in N-methyl pyrrolidone (NMP) in a weight ratio of 80:10:10, mixed uniformly, and prepared into a uniform positive electrode slurry. The uniform positive electrode slurry was uniformly coated on an aluminum foil current collector with a thickness of 15 μm, dried at 55°C, formed into a pole piece with a thickness of 100 μm, placed under a roll press (pressure about 1 MPa x 1.5 cm2), cut into a circular piece with a diameter of φ 14 mm, then placed in a vacuum oven at 120°C for 6 h, naturally cooled, taken out and placed in a glove box for use as a positive electrode pole piece.

[0057] 2) Assembling lithium ion secondary batteries

[0058] In a glove box filled with an inert atmosphere, metal lithium was used as the negative electrode of the battery, a PP / PE / PP three-layer film coated with aluminum oxide on both sides was used as a separator between the positive electrode and the negative electrode, and a commonly used carbonate electrolyte was added dropwise. The positive electrode pole piece prepared in step 1) was used as the positive electrode to assemble a button cell with a model of CR2032.

[0059] Battery rate cycling performance test:

[0060] After the button cell prepared above was left standing at room temperature (25°C) for 10 h, the button cell was subjected to charge-discharge activation, and then the button cell prepared above was subjected to charge-discharge cycling test using a blue cell charge-discharge tester. The specifics are as follows:

[0061] At 25°C, 0.1C rate was cycled for 1 week, 1C rate was cycled for 5 weeks, 5C rate was cycled for 5 weeks, and then 1C rate was cycled for 39 weeks. The discharge capacity and capacity retention rate of the button cells assembled with the positive electrode active materials of samples 1-3, and comparative examples 1 and 2 at 1C and 5C are shown in Table 1 below;

[0062] Table 1:

[0063]

[0064] Low temperature rate performance test

[0065] Samples 1-2 and comparative sample 1 were prepared into button cells, first activated at 0°C at a rate of 0.05C for three weeks, charged at 0°C at a rate of 0.2C to 4.9V, and then discharged at a rate of 3C.

[0066] Table 2:

[0067]

[0068] From the above table 2, it can be concluded that the sample prepared in the present application has a significant improvement in the low-temperature high-rate discharge capacity compared with the comparative sample.

[0069] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only preferred examples of the present application and are not intended to limit the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A composite high-voltage lithium-ion battery positive electrode material, characterized in that: The invention comprises a positive electrode active material, a coating layer and a transition layer, wherein the coating layer is a niobium-based composite fast-charging material, and the niobium-based composite fast-charging material is coated on the positive electrode active material; The positive electrode active material and the niobium-based composite fast-charging material form the transition layer during the coating process; The positive electrode active material includes a chemical formula of Li x M y O z Lithium-containing compound particles, wherein 0.8≤x≤2.2, 0.8≤y≤2.2, and 1.8≤z≤4.2; and M is at least one of Na, K, Al, Mg, Zn, Ni, Mn, Fe, Co, Ti, Y, Sc, Ru, Cu, Mo, Ge, W, Zr, Ca, Nb, Ta, P, S, F, B, Si, Ba, Pb, V, In, Ga, Sb, Bi, and Sr.

2. The composite high-voltage lithium-ion battery positive electrode material according to claim 1, characterized in that: The positive electrode active material is LiNi with a spinel structure 0.5-k Mn 1.5-m M p O 4-n , wherein M is selected from one or more doping elements of Mg, Fe, Co, Y, Sc, Ru, Cu, Mo, Ce, W, Zr, Ca, P, S, F, B, Si and Sr, -0.2≤k≤0.2, -0.2≤m≤0.2, 0≤p≤0.1, and -0.2≤n≤0.

2.

3. The composite high-voltage lithium-ion battery positive electrode material according to claim 1, characterized in that: The niobium-based composite fast-charging material is: NiM a Nb 2+b O6、TiM a Nb 2+b O7、Ti2M a Nb 10+b O 29 、M c Nb d O e and Ti2M a Nb 24+b O 62 wherein, 0≤a≤0.2, -0.4≤b≤0.4, 0<c≤1, 0<d≤1, 0<e≤1, and M is at least one of Na, K, Al, Mg, Zn, Ni, Mn, Fe, Co, Ti, Y, Sc, Ru, Cu, Mo, Ge, W, Zr, Ca, Nb, Ta, P, V, S, F, B, Si, Ba, Pb, In, Ga, Sb, Si, Bi, and Sr.

4. The composite high-voltage lithium-ion battery positive electrode material according to claim 1, characterized in that: The Li x M y O z Includes the following positive electrode active materials: LiCoO2, LiMnO2, LiNiO2, LiVO2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2、LiMn2O4、Li(Ni 0.5 Mn 1.5 )O4, Li2FeSiO4, Li2MnSiO4, and doped and coated derivatives of the foregoing positive electrode active materials.

5. The composite high-voltage lithium-ion battery positive electrode material according to claim 3, characterized in that: The niobium-based composite fast-charging material is: Ni 0.166 Nb 0.333 O(NiNb2O6), Ti 0.142 Nb 0.286 O(TiNb2O7), Ti 0.069 Nb 0.345 O(Ti2Ni 10 O 29 ),Mg 0.023 Nb 0.391 O(Mg2Nb 34 O 87 ), Zn 0.023 Nb 0.391 O(Zn2Nb 34 O 87 )、Mo 0.030 Nb 0.364 O(MoNb 12 O 33 ), Ga 0.008 Nb 0.395 O(GaNb 49 O 124 ), Zr 0.16 1Nb 0.387 (ZrNb 24 O 62 ) and Ti 0.032 Nb 0.387 O(Ti2Nb 24 O 62 ) and their doped and coated derivatives.

6. A composite high-voltage lithium-ion battery positive electrode material according to any one of claims 1 to 5, characterized in that: The thickness of the coating layer is 2nm to 2000nm; The thickness of the niobium-based composite fast-filling material phase is 2 nm to 2000 nm; The particle size of the positive electrode active material is 0.1 μm to 30 μm.

7. A method for preparing a composite high-voltage lithium-ion battery positive electrode material, for preparing the composite high-voltage lithium-ion battery positive electrode material according to any one of claims 1 to 6, characterized in that: The steps include: uniformly mixing the raw material of the positive electrode active material with the niobium-based fast charging material or its precursor to obtain a mixture; The obtained mixture is sintered in an atmosphere containing oxygen to prepare the positive electrode active material.

8. The method for preparing a composite high-voltage lithium-ion battery positive electrode material according to claim 7, characterized in that: The median particle size D50 of the positive electrode active material is 2 to 20 μm, and the median particle size D50 of the niobium-based fast charging material is 2 to 2000 nm; The heating and cooling rate of the sintering is 0.5-8°C / min, and the mixing and sintering is carried out at 400-1200°C for 1-10 hours.

9. A lithium battery positive electrode, characterized in that: The present invention comprises a current collector on which the composite high-voltage lithium-ion battery positive electrode material according to any one of claims 1 to 6 is loaded.

10. A lithium battery, characterized in that: The invention comprises at least two of a separator, an electrolyte, a negative electrode, and a lithium supplement agent, and a composite high-voltage lithium-ion battery positive electrode material according to any one of claims 1 to 6.

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