Manganese potassium vanadate coated modified ternary positive electrode material and preparation method and application thereof

Abstract

The application provides a kind of manganese potassium vanadate coated modification ternary positive electrode material and its preparation method and application, belong to lithium ion battery technical field.The method takes ternary positive electrode material precursor Ni x Co y Mn z (OH)2, lithium source material and dopant are mixed, first sintering treatment is carried out, ternary positive electrode material doped matrix is obtained;Ternary positive electrode material doped matrix is mixed with manganese potassium vanadate coated agent containing, and second sintering treatment is carried out, and ternary positive electrode material coated matrix is obtained;Finally, ternary positive electrode material coated matrix is mixed with manganese potassium vanadate additive containing, and third sintering treatment is carried out, and manganese potassium vanadate coated modification ternary positive electrode material is obtained.The nickel cobalt manganese ternary positive electrode single crystal and secondary ball particle prepared by the application are good in dispersibility, uniform in size, high in sphericity, high in powder tap density, high in structural stability, high in ion mobility, high in electronic conductivity, low in DCIR, long in cycle and other advantages.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium ion batteries, and particularly relates to a potassium manganese vanadate coated modified ternary positive electrode material and a preparation method and application thereof. BACKGROUND

[0002] With the development of power batteries and the adjustment of global economic energy pattern, the comprehensive performance requirements of NCM / NCMA / NCA positive electrode materials are increasingly high, therefore, the modification of ternary positive electrode materials has become a research hotspot. Lithium ion power batteries are accompanied by the market challenges of new energy vehicles in recent years, the metal resource market is periodically adjusted, but the overall demand is rising, and the cost problem is quite prominent. The performance-price ratio of positive electrode material products has become the consensus of the industry development trend and each enterprise, and the high-voltage and high-nickel in the future have a larger market space, which is the key direction of technology research and development and industrialization of each ternary positive electrode material manufacturer.

[0003] The modification of ternary positive electrode materials is generally divided into doping and coating. Through doping other elements, the capacity, cycle performance and rate performance of the material can be improved by effectively improving the microcrack formation of ternary positive electrode material NCM, reducing electrolyte decomposition and expanding ion diffusion channels; through coating metal oxides or conductive carbon or carbon nanotubes or graphene, the structure stability of NCM ternary positive electrode material can be effectively improved, and the electronic conductivity can be improved by constructing a conductive network, so as to improve the rate and cycle performance of the material. The existing doped materials mostly include Ti and Zr, but the modification efficiency of Ti and Zr alone in the existing materials on the lithium ion battery positive electrode material is poor, which not only cannot improve the performance of ternary positive electrode material NCM well, but also has high cost and low efficiency. In addition, with the increase of the content of nickel element in the material, the residual lithium on the surface of the material will continuously increase. In the battery, the residual lithium will have a side reaction with the electrolyte to cause the battery to swell, the cycle performance will be poor, and a certain safety risk will be brought. The conventional coating and doping methods cannot effectively reduce the content of residual lithium on the surface of the material.

[0004] Chinese patent CN 111416106 B discloses a preparation method of potassium metavanadate dispersed coated nickel-cobalt-manganese ternary positive electrode material. The preparation method of potassium metavanadate dispersed coated nickel-cobalt-manganese ternary positive electrode material is adopted, a ternary composite precursor (Ni x Co y Mn z)2, then washed with deionized water, beaten, filtered to obtain a slurry, and then a lithium source and potassium metavanadate were added to the slurry to sequentially perform homogenization refinement treatment, spray drying and high-temperature calcination to obtain the potassium metavanadate dispersion-coated nickel-cobalt-manganese ternary positive electrode material. By coating KVO3 on the surface of the ternary positive electrode, the surface structure stability of the material is improved, and the ion mobility of the material is improved, thereby improving the electrochemical performance of the ternary material; the dispersion is good, the size is uniform, the sphericity is high, the secondary particles are loose, which is beneficial to the infiltration of the electrolyte, thereby improving the diffusion rate of lithium ions, and improving the rate performance and cycle performance.

[0005] As disclosed in Chinese Patent CN 113013389 A, a ternary positive electrode material coated with a manganese oxide compound and a preparation method thereof are disclosed, the molar ratio of the coating base and the manganese oxide compound is 1:0.01-0.2, and a preparation method of the ternary positive electrode material is provided. In the present application, potassium permanganate is used to oxidize the surface Ni 2+ of the material to N i 3+ , and a layer of manganese oxide compound is uniformly coated on the surface of the material, which reduces the residual lithium on the surface of the material, reduces the side reaction of residual lithium and electrolyte in the battery, and improves the cycle performance and safety performance of the material.

[0006]

[0007] As disclosed in Chinese Patent CN 111900394B, a coating structure of a lithium ion battery positive electrode material and a preparation method and use thereof are disclosed, the electronic conductive particle layer includes at least one of metal particles, carbon particles and conductive oxide particles; at least one of lithium meta-aluminate, lithium niobate, lithium titanate, lithium borate, lithium metaborate, lithium zirconate, lithium lanthanum zirconium oxide, lithium lanthanum titanium oxide, titanium aluminum lithium phosphate, germanium aluminum lithium phosphate and lithium phosphorus oxygen nitrogen is selected, wherein the compound containing niobium element lithium niobate is used. Another disclosed single-crystal ternary positive electrode material and a preparation method and process thereof use niobium oxide for doping modification;

[0008] As disclosed in Chinese Patent CN 113903907A, a tungsten-coated and doped single-crystal nickel-rich ternary positive electrode material is disclosed, which uses W for doping and coating to obtain a tungsten-coated and doped single-crystal nickel-rich ternary positive electrode material, effectively enhances the structural stability of the single-crystal nickel-rich ternary positive electrode material, reduces the polarization of the material, improves the lithium ion diffusion kinetics, and thus improves the cycle stability and rate performance of the battery. However, single use of tungsten element for modification cannot better improve the structural stability.

[0009] ​For example, Chinese patent CN111900401A discloses a method for coating lithium battery positive electrode material with tungsten oxide and nitrogen-doped carbon, which uses the polymerization of carbon precursor and the precipitation of tungsten precursor on the surface of lithium battery positive electrode material to form a coating layer, and then realizes the solidification and bonding of the coating layer through calcination process. It has the characteristics of low cost, low energy consumption and simple operation. The lithium battery positive electrode material has excellent electronic conductivity and electrochemical stability. However, it mainly involves adding tungsten-containing solution to the precursor, which is difficult to control the amount of introduction and the related parameters of the coprecipitation reaction, and its effect has certain limitations.

[0010] For example, Chinese patent CN112531154A discloses a ternary material gradient-doped with tungsten trioxide microparticles, which realizes tungsten doping through a precursor wet synthesis stage, activates the surface layer of the material with hydrogen peroxide solution under normal temperature and pressure, and recrystallizes the material after doping tungsten under low temperature sintering conditions. This can realize the gradient distribution of tungsten element in the ternary material from the surface to the inside at atomic level. The crystal nucleus formed by tungsten element and nickel, cobalt and manganese effectively fills the gap between the secondary particles of ternary material, stabilizes the composition structure of ternary material, and solves the problems of uneven tungsten doping and high sintering temperature caused by high energy consumption.

[0011] For example, Chinese patent CN113764647A discloses a ternary positive electrode material precursor and ternary positive electrode material doped with zirconium and multi-anions, which provides a ternary precursor scheme co-doped with Zr and multi-anions. It mainly uses compounds of anions and cations to mix and add modified materials in the precursor solution end. However, it still needs further modification in the high-temperature calcination preparation stage due to the element interface fusion and the growth defects of crystal boundary diffusion in the later stage.

[0012] For example, Chinese patent CN107706390B discloses a preparation method of lithium ion battery ternary positive electrode material double-modified with fast ion conductor and conductive polymer. The preparation method mainly discloses a lithium ion battery ternary positive electrode material double-modified with fast ion conductor and conductive polymer. The lithium ion battery ternary positive electrode material is the core, the fast ion conductor is the first coating layer, and the conductive polymer is the second coating layer. The fast ion conductor is any one of lithium vanadate, lithium metavanadate and lithium zirconate. First, mix and grind the fast ion conductor and the ternary positive electrode material, then use high-temperature solid-phase method to coat the fast ion conductor on the ternary positive electrode material, then mix and ball mill the conductive polymer with the ternary positive electrode material coated with the fast ion conductor, and coat the conductive polymer on the ternary positive electrode material coated with the fast ion conductor. Finally, obtain the lithium ion battery ternary positive electrode material double-modified with fast ion conductor and conductive polymer. The invention combines fast ion conductor and conductive polymer to modify the ternary positive electrode material, which not only has excellent cycle performance, but also has good rate performance.

[0013] For example, Chinese patent CN113307310B discloses a preparation method of a molybdenum-doped titanium dioxide-coated high-nickel ternary positive electrode material with high cycle performance, wherein the high-nickel ternary positive electrode material is LiNi 0.9 Co 0.05 Al 0.05 O2;Mo 6+ The doping of TiO2 forms vacancy defects, improves the electronic conductivity of TiO2, and improves the rate performance of the high-nickel ternary positive electrode material. At the same time, the Mo-doped TiO2 coating layer separates the high-nickel ternary positive electrode material from the electrolyte, avoids the corrosion of the active material high-nickel ternary positive electrode material by trace HF in the electrolyte, and improves the cycle performance of the high-nickel ternary positive electrode material, so that the in-situ generated Mo-doped TiO2-coated high-nickel ternary positive electrode material has excellent cycle performance and rate performance;

[0014] For example, Chinese patent CN114023939A discloses a ternary positive electrode material doped with titanium and zirconium and coated with vanadium and a preparation method thereof. The material of the coating layer includes vanadium oxide, the ternary positive electrode material contains titanium elements, zirconium elements and NCM ternary precursors, the molar ratio of Ni, Co and Mn in the NCM ternary precursor is 7:1:2, the first step of the preparation is to uniformly mix the NCM ternary precursor, lithium hydroxide monohydrate, nanoscale titanium dioxide and nanoscale zirconium oxide, then stir and mix with ion water containing vanadium oxide again after sintering, dry and sinter, and then a ternary positive electrode material doped with titanium and zirconium and coated with vanadium is obtained. The method is simple to operate, the process and technology are easy to implement, the doping amount is easy to control, and the method can be used for large-scale commercial application and can be used for doping other ternary positive electrode materials or lithium-rich positive electrode materials. SUMMARY

[0015] The purpose of the present application is to provide a manganese potassium vanadate coated modified ternary positive electrode material and a preparation method and application thereof. The nickel-cobalt-manganese modified ternary positive electrode material has the advantages of good dispersity, uniform size, high sphericity, high powder tap density, high conductivity, high ion mobility, stable structure, high rate / cycle / storage performance, and the like. The gradient coating further improves the surface structure stability of the material and improves the ion mobility of the material, thereby improving the electrochemical performance of the ternary material, which is beneficial to improving the electrode compaction density and electrolyte wettability. The material has the advantages of high structural stability, high ion mobility, high electronic conductivity, low DCIR, high rate / storage / long cycle, and the like.

[0016] To solve the above technical problems, the present application adopts the following technical solutions:

[0017] The present application first provides a manganese potassium vanadate coated modified ternary positive electrode material, which has the general formula: LiNix Co y Mn z W a Al b Y c Zr d Ti e Nb f V g K h O2, and x+y+z+a+b+c+d+e+f+g+h=1.

[0018] The application also provides a preparation method of the modified ternary cathode material coated with potassium manganese vanadate, comprising the following steps:

[0019] (1) taking a ternary cathode material precursor Ni x Co y Mn z (OH)2, a lithium source material and a dopant, mixing and performing first sintering treatment to obtain a ternary cathode material doped substrate;

[0020] (2) mixing the ternary cathode material doped substrate in step (1) with a potassium manganese vanadate coating agent containing K2MnV2O7, Zr 0.97 Y 0.03 O2, NbO2 and TiO2, and performing second sintering treatment to obtain a ternary cathode material coated substrate;

[0021] (3) mixing the ternary cathode material coated substrate in step (2) with a potassium manganese vanadate additive containing Li2O6V2 and K2MnV2O7, and performing third sintering treatment to obtain a modified ternary cathode material coated with potassium manganese vanadate.

[0022] Preferably, in step (1), the molar ratio of the ternary cathode material precursor Ni x Co y Mn z (OH)2, the lithium source material (calculated as Li + ) and the dopant (calculated as the total amount of doping metal elements) is 1:(0.90-1.18):(0.002-0.10).

[0023] Preferably, the dopant comprises a mixture of WO3, Y2O3, Zr 0.97 Y 0.03 O2 and β-Al2O3; the WO3, Y2O3, Zr 0.97 Y 0.03The mass ratio of O2 and β-Al2O3 is (0.01-0.60):(0.01-0.30):(0.01-0.50):(0.01-0.50).

[0024] Preferably, the first sintering step in step (1) comprises: first heating to 400-580 DEG C under an oxygen-containing atmosphere for 2-8h, then second heating to 580-740 DEG C for 2-6h, and third heating to 740-1000 DEG C for 8-20h.

[0025] Preferably, in step (2), the molar ratio of the ternary positive electrode material doped substrate to the potassium manganese vanadium acid containing coating agent (based on the total amount of coating elements) is 1:(0.02-0.50).

[0026] Preferably, the potassium manganese vanadium acid containing coating agent contains K2MnV2O7, Zr 0.97 Y 0.03 The mass ratio of O2, NbO2 and TiO2 is (0.01-0.75):(0.01-0.30):(0.01-0.20):(0.01-0.35).

[0027] Preferably, the second sintering in step (2) is calcination at 350-780 DEG C for 1-20h.

[0028] Preferably, the mass ratio of the positive electrode material coating substrate to the potassium manganese vanadium acid containing additive is 100:(0.01-0.90).

[0029] The application also provides the use of the above-mentioned potassium manganese vanadium acid coated modified ternary positive electrode material or the potassium manganese vanadium acid coated modified ternary positive electrode material prepared by the method for preparing a secondary battery positive electrode sheet or a secondary battery.

[0030] Advantages of the application

[0031] The application provides a potassium manganese vanadium acid coated modified ternary positive electrode material, a preparation method and application thereof. 0.97 Y 0.03 O2 and β-Al2O3 are doped and modified; wherein the W / Y element characteristics of the WO3 and Y2O3 dopants promote particle growth and improve internal conductivity, which can improve the compaction resistance and reduce the calcination temperature to reduce energy consumption; high-temperature sintering solid phase reaction makes W / Zr / Y / Al diffuse inward, which together inhibits cation mixing, increases the interlayer spacing, and improves the ion migration ability; especially WO3 is converted into an orange tetragonal crystalline body at a temperature higher than 740 DEG C, and returns to the original state after cooling, combined with Y2O3 hexagonal Zr0.97 Y 0.03 O2Monoclinic crystal enhances the structural stability, and has certain structural stability when treated at low temperature by beta-Al2O3, and the structural evolution characteristics of the stable alpha phase transition at high temperature further improve the structure and thermal stability of nickel-cobalt-manganese ternary materials, improve the reversible capacity, reduce the side reaction between the active material and the electrolyte, reduce the solubility of manganese in the organic electrolyte, effectively improve the cycle performance of the material at high voltage or high nickel content, and can widen the ion channel and interlayer distance, improve the discharge efficiency and rate capability of the material, improve the high-temperature electrochemical performance of the material, reduce the Li / Ni mixing degree, and protect the application performance of the battery product.

[0032] The vanadate potassium coated modified ternary positive electrode material further adopts K2MnV2O7, Zr 0.97 Y 0.03 O2, NbO2 and TiO2 as coating agents for coating modification;wherein, the conductivity mechanism can be further improved by using K2MnV2O7 to add a small amount of TiO2 and combine reaction, and the small particle processing characteristics are improved, and the NbO2 and TiO2 reaction mechanism is used simultaneously: Nb 5+ When TiO2 is doped, when Ti 4+ Ions are replaced by Nb 5+ Ions, the electrical conductivity can be improved. Among them, because the radius of Nb 5+ Is close to that of Ti 4+ , surface coating and doping can be carried out without affecting the stability of the cubic perovskite structure. Because V 5+ Nb 5+ The valence is higher than that of Ti 4+ , when doped, electrons will be introduced into the system, so that V / Nb / Ti / Zr / Y forms a surface doping characteristic, and the surface particle morphology is repaired to improve the surface conductivity of the ternary positive electrode material, improve the particle surface corrosion resistance and high temperature performance;Reduce the increase of DCR and cycle impedance of the battery;Can effectively improve the material surface resistance to electrolyte corrosion, material rate, surface conductivity, ion migration ability, etc.;Through Nb / Y coating, the discharge capacity, initial efficiency and cycle performance can be improved, and the application performance of the battery product is protected.

[0033] The vanadate potassium coated modified ternary positive electrode material further adopts L i2O6V2, K2MnV2O7 and N i / Co / Mn / T i / Y / W / Zr / Al / K / V / Nb oxide matrix to form secondary coating after mixing, to form a surface fast ion conductor gradient coating layer, which can effectively improve the surface conductivity, while reducing the surface residual alkali, thereby inhibiting the occurrence of interface side reaction, effectively enhancing the surface gradient coating protective layer, and further increasing the Li ion migration induction ability, improving the cycle performance of the material.

[0034] The vanadium potassium manganese oxide coated modified ternary positive electrode material adopts a gradient modification method of multi-element composite doping coating, and through the synergistic effect of W / Y / / Al / Zr doping and Ti / K / V / Nb / Li / Mn coating, the Li / Ni mixing and the particle surface band effect in the positive electrode material are effectively improved, the structural stability and thermal stability, the rate / cycle / storage performance, DCIR, etc. of the ternary positive electrode material are improved, the layered structure is more stable, the electronic conductivity is higher, the rate, long cycle / storage and low DCIR are superior. The lithium ion battery prepared by the vanadium potassium manganese oxide coated modified ternary positive electrode material provided by the application has high specific capacity, rate and cycle performance and application effect, has the advantages of high specific capacity, low DCIR growth, long cycle performance and excellent comprehensive performance. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to make the content of the application more easily understood, the application will be further described in detail below according to specific embodiments of the application and in combination with the drawings, in which,

[0036] Figure 1 The XRD characterization chart of Example 1;

[0037] Figure 2 The preparation process flow chart of the vanadium potassium manganese oxide coated modified ternary positive electrode material of the application;

[0038] Figure 3 The SEM morphology characteristics of the positive electrode materials prepared in Examples 1 and 2 are shown in (a) and (b) respectively;

[0039] Figure 4 The charge-discharge curves of the positive electrode materials prepared in Examples 1 and 2 are shown in (a) and (b) respectively;

[0040] Figure 5 The cycle curves of the coin cells in Examples 1 and 2 and Comparative Examples 1 and 2 are shown in (a) and (b) respectively;

[0041] Figure 6 The full battery 25℃ and 45℃ cycle curves in Examples 1 and Comparative Example 1 are shown in (a) and (b) respectively. DETAILED DESCRIPTION

[0042] The application first provides a vanadium potassium manganese oxide coated modified ternary positive electrode material, the general formula of the positive electrode material is: LiNi x Co y Mn z W a Al b Y c Zr d Ti e Nb f Vg K h O2, and x+y+z+a+b+c+d+e+f+g+h=1.

[0043] Preferably, in the potassium manganese vanadate coated modified ternary positive electrode material, Ni x molar ratio 0.5≤x<1.0, Co y molar ratio 0<y≤0.30, Mn z molar ratio 0<z≤0.40, and x+y+z=1; Li: (x+y+z) molar ratio is preferably 0.92-1.12:1.0, more preferably 0.98-1.08:1.0.

[0044] The application also provides a preparation method of the potassium manganese vanadate coated modified ternary positive electrode material, comprising the following steps:

[0045] (1) taking a ternary positive electrode material precursor Ni x Co y Mn z (OH)2, a lithium source material, and a dopant, and performing first sintering treatment to obtain a ternary positive electrode material doped substrate; the dopant comprises a mixture of WO3, Y2O3, Zr 0.97 Y 0.03 O2, and β-Al2O3.

[0046] (2) mixing the ternary positive electrode material doped substrate in step (1) with a potassium manganese vanadate coating agent containing potassium manganese vanadate coating agent, and performing second sintering treatment to obtain a ternary positive electrode material coated substrate; the potassium manganese vanadate coating agent containing potassium manganese vanadate coating agent comprises a mixture of K2MnV2O7, Zr 0.97 Y 0.03 O2, NbO2, and TiO2.

[0047] (3) mixing the ternary positive electrode material coated substrate in step (2) with a potassium manganese vanadate additive containing potassium manganese vanadate additive, and performing third sintering treatment to obtain a potassium manganese vanadate coated modified ternary positive electrode material.

[0048] According to the application, in step (1), the molar ratio of the ternary positive electrode material precursor Ni x Co y Mn z (OH)2, the lithium source material (calculated as Li + ), and the dopant (calculated as the total amount of doping metal elements) is preferably 1:(0.90-1.18):(0.002-0.10); more preferably 1:(0.94-1.12):(0.002-0.08), and most preferably 1:(0.96-1.08):(0.01-0.07);

[0049] According to the present invention, the dopant WO3, Y2O3, Zr 0.97 Y 0.03 The mass ratio of O2 and β-Al2O3 is preferably (0.01-0.60): (0.01-0.30): (0.01-0.50): (0.01-0.50). Specifically, the positive electrode material precursor Ni x Co y Mn z The mass ratio of (OH)2 to the WO3 is preferably 100:(0.01-0.60); more preferably 100:(0.1-0.48), and most preferably 100:(0.15-0.38); the purity of the dopant WO3 is 99.8%, and its D 50 The particle size is preferably 0.5 μm-10 μm, more preferably 1 μm-8 μm, and most preferably 1.5 μm-5 μm;

[0050] The cathode material precursor Ni x Co y Mn z The mass ratio of (OH)2 to the Y2O3 is preferably 100:(0.01-0.30), more preferably 100:(0.03-0.25), and most preferably 100:(0.06-0.20); the purity of the dopant Y2O3 is 99.9%, and its D 50 The particle size is preferably 0.1 μm-15 μm, more preferably 0.5 μm-15 μm, and most preferably 1 μm-10 μm;

[0051] The cathode material precursor Ni x Co y Mn z (OH)2 and the Zr 0.97 Y 0.03 The mass ratio of O2 is preferably 100:(0.01-0.50), more preferably 100:(0.05-0.40), and most preferably 100:(0.1-0.35); the dopant Zr 0.97 Y 0.03 O2 purity 99.9%, its D 50 The particle size is preferably 0.5 μm-15 μm, more preferably 1 μm-12 μm, and most preferably 1.5 μm-6 μm;

[0052] The cathode material precursor Ni x Co y Mn zThe mass ratio of (OH)2 to the β-Al203 is preferably 100:(0.01-0.50), more preferably 100:(0.04-0.40), and most preferably 100:(0.06-0.30); the purity of the dopant β-Al203 is 99.9%, and its D 50 The particle size is preferably 0.1 μm-20 μm, more preferably 0.2 μm-15 μm, and most preferably 0.5 μm-10 μm;

[0053] According to the present application, the lithium source material is a lithium-containing compound, preferably including one or a mixture of several of LiOH, LiOH-H20, CH3COOLi, Li2CO3, or LiNO3, and more preferably LiOH-H20, Li2CO3. In use, the coarse lithium source can be mechanically ground to 3-20 μm or a lithium source of such specifications can be selected from the market, preferably 4-12 μm.

[0054] According to the present application, the selection of the ternary positive electrode material precursor has a small-particle ternary precursor particle size D 50 (2.0-8.0 μm), preferably 3.0-6.0 μm; and a large-particle ternary precursor particle size D 50 (9-18 μm), preferably 10-15 μm.

[0055] According to the present application, the mixing step uses a ball mill or jar mill, a plow mixer or a high-speed mixer to mix the materials uniformly, and then the materials are shaken and cut into pieces in a small dry pot or a sagger before being sintered once; the mixing equipment is preferably a ball mill, a plow mixer, or a high-speed mixer.

[0056] The first sintering step preferably includes the steps of first temperature rising to 400-580°C under an oxygen-containing atmosphere, holding for 2-8 h, second temperature rising to 580-840°C, holding for 2-6 h, and third temperature rising to 740-1000°C, holding for 8-20 h;

[0057] As a more preferred solution, in the step (1), the first sintering step includes the steps of first temperature rising to 420-560°C under an oxygen-containing atmosphere, holding for 3-6 h, second temperature rising to 620-740°C, holding for 3-5 h, and third temperature rising to 740-1000°C, holding for 8-16 h;

[0058] As a most preferred solution, in the step (1), the first sintering step includes the steps of first temperature rising to 460-530°C under an oxygen-containing atmosphere, holding for 4-6 h, second temperature rising to 680-720°C, holding for 3-4 h, and third temperature rising to 740-1000°C, holding for 9-14 h.

[0059] According to the present application, when the first sintering step is carried out in a muffle furnace or tube furnace mode, the heating rate of the first heating, second heating and third heating steps is preferably independently controlled at 1-5℃ / min, more preferably the heating rate is 2-4℃ / min, most preferably the heating rate is 3℃ / min;

[0060] According to the present application, when the first sintering step is carried out in an atmosphere roller kiln or rotary furnace mode, the heating rate of the first heating, second heating and third heating steps is preferably independently controlled at 1-30℃ / h, more preferably the heating rate is 5-20℃ / h, most preferably the heating rate is 10℃ / h.

[0061] According to the present application, the atmosphere selected in the first sintering process is oxygen, with a concentration of ≥95%, and after the first sintering, coarse crushing, fine crushing, sieving and magnetic removal are carried out to obtain a ternary positive electrode material doped substrate for subsequent coating. Preferably, the particle size of the large particle substrate of the ternary positive electrode material doped substrate after crushing and sieving is D 50 9-16μm, preferably 10-14μm; and the particle size of the small particle substrate is D 50 2.5-6.0μm, preferably 3.0-5.0μm.

[0062] According to the present application, in step (2), the molar ratio of the ternary positive electrode material doped substrate to the potassium manganese vanadate coating agent (based on the total amount of coating elements) is preferably 1:(0.02-0.50).

[0063] The potassium manganese vanadate coating agent includes K2MnV2O7, Zr 0.97 Y 0.03 O2, NbO2and TiO2; the mass ratio of the positive electrode material doped substrate to the K2MnV2O7 is preferably 100:(0.01-0.75), more preferably 100:(0.05-0.60), most preferably 100:(0.10-0.48); the purity of the coating agent K2MnV2O7 is 99.5%, and the D 50 particle size is preferably 10nm-120nm;

[0064] The mass ratio of the positive electrode material doped substrate to the Zr 0.97 Y 0.03 O2 is preferably 100:(0.01-0.30), more preferably 100:(0.05-0.25), most preferably 100:(0.08-0.18); the purity of the coating agent Zr 0.97 Y 0.03 O2 is 99.9%, and the D 50The particle size is preferably 20-100 nm;

[0065] The mass ratio of the positive electrode material doped matrix to the NbO2 is preferably 100:(0.01-0.20), more preferably 100:(0.05-0.18), and most preferably 100:(0.06-0.15); the purity of the coating agent NbO2 is 99.9%, and the D 50 The particle size is preferably 20-120 nm;

[0066] The mass ratio of the positive electrode material doped matrix to the TiO2 is preferably 100:(0.01-0.35), more preferably 100:(0.03-0.25), and most preferably 100:(0.05-0.20); the purity of the coating agent TiO2 is 99.8%, and the D 50 The particle size is preferably 10-180 nm;

[0067] According to the present application, in the step (2), the second sintering step preferably comprises the step of calcining at a temperature of 350-780°C and maintaining the temperature for 1-20 hours; more preferably, the calcining temperature is 360-770°C, and the maintaining time is 3-14 hours; most preferably, the calcining temperature is 380-760°C, and the maintaining time is 6-11 hours.

[0068] According to the present application, in the second sintering step, the temperature increasing rate is preferably 1-20°C / h.

[0069] According to the present application, after the second sintering and the temperature decreasing, the positive electrode material coated matrix is obtained by colloid mill crushing and magnetic separation.

[0070] According to the present application, in the step (3), the vanadium-containing manganese potassium additive preferably comprises Li2O6V2 and K2MnV2O7.

[0071] The mass ratio of the positive electrode material coated matrix to the Li2O6V2 is preferably 100:(0.01-0.90), more preferably 100:(0.1-0.75), and most preferably 100:(0.2-0.60); the purity of the coating agent Li2O6V2 is 99.9%, and the D 50 The particle size is preferably 60-150 nm.

[0072] The mass ratio of the positive electrode material coated matrix to the K2MnV2O7 is preferably 100:(0.01-0.50), more preferably 100:(0.05-0.40), and most preferably 100:(0.08-0.30); the purity of the coating agent K2MnV2O7 is 99.5%, and the D 50 The particle size is preferably 100-200 nm.

[0073] According to the present application, in the step (3), the third sintering step preferably comprises the step of calcining at a temperature of 180-480 DEG C and holding for 1-10 h; more preferably, the calcining temperature is 200-460 DEG C, and the holding time is 3-8 h; most preferably, the calcining temperature is 220-420 DEG C, and the holding time is 4-7 h;

[0074] According to the present application, in the third sintering step, the temperature rising rate is preferably 1-20 DEG C / h;

[0075] Specifically, the equipment for the coating operation can adopt a high-speed mixer, a mechanical fusion machine, and preferably a high-speed mixer.

[0076] According to the present application, in the step (3), the obtained manganese potassium vanadate coated modified ternary positive electrode material is further subjected to the steps of crushing, sieving, and magnetic removal; and can be further mixed uniformly in a batch mixing tank and is protected by introducing dry gas (dehydrated carbon dioxide) or inert gas.

[0077] According to the present application, in the step (3), the large particle matrix particle size D 50 of the manganese potassium vanadate coated modified ternary positive electrode material is preferably 8-18 μm, more preferably 9-16 μm, and most preferably 10-15 μm; and the small particle matrix particle size D 50 of the manganese potassium vanadate coated modified ternary positive electrode material is preferably 2.5-6.4 μm, more preferably 2.8-6.2 μm, more preferably 3.0-5.8 μm, and most preferably 3.2-4.8 μm.

[0078] According to the present application, the batch mixing equipment can adopt a screw belt batch mixing machine or a high-speed mixer.

[0079] The present application also discloses the use of the manganese potassium vanadate coated modified ternary positive electrode material or the manganese potassium vanadate coated modified ternary positive electrode material prepared by the method for preparing a positive electrode sheet of a secondary battery or a secondary battery; and the secondary battery preferably comprises a lithium ion battery.

[0080] The present application also discloses a positive electrode sheet of a secondary battery or a secondary battery prepared from the manganese potassium vanadate coated modified ternary positive electrode material or the manganese potassium vanadate coated modified ternary positive electrode material prepared by the method.

[0081] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application.

[0082] In the following embodiments of the present invention, the K2MnV2O selected can be purchased from the market with the same required specifications, or can be prepared according to traditional synthesis methods. For example, the conductivity of the vanadate is 10-3 to 10-2 S / cm at 300-500°C; the specific steps of the preparation method of the vanadate are as follows: (1) the original powders of K2CO3, MnO and V2O5 are weighed and mixed according to the composition of K2MnV2O7 and placed in a ball mill, zirconium oxide balls with a diameter of 7mm are added, ball milled for 10 hours, mixed and ground evenly, and then taken out and dried to obtain a powder raw material; (2) the powder raw material dried in step (1) is pressed into a columnar sample, placed on a ceramic support plate, covered with a crucible, and then placed in a tube furnace, calcined at 500°C, kept warm for 2 hours, and then cooled to room temperature with the furnace and crushed and ground into powder; the ground powder is placed in a beaker, deionized water is added, and the beaker is placed in an ultrasonic cleaner, ultrasonically cleaned for 2 minutes to remove KVO3, and the remaining sample is filtered; and the drying is carried out. The remaining dry sample is continued to be placed in a beaker, and then a certain amount of ammonium chloride solution is added. The beaker is then placed in an ultrasonic cleaning machine for ultrasonic cleaning for 2 minutes. After the ultrasonic cleaning is completed, deionized water is continued to be added to the beaker, and ultrasonic cleaning is continued for 2 minutes. The solution is filtered to obtain a precipitate, and the precipitate is dried and ground to obtain a powder sample; (3) The powder sample obtained in step (2) is placed in a ball mill, and zirconium oxide balls with diameters of 2 mm and 7 mm are added. The powder sample and the zirconium oxide balls are ball milled in the ball mill for 15 hours, mixed and ground evenly to obtain a powder sample; (4) The powder sample after ball milling in step (3) is cold isostatically pressed at 20 MPa to form a disc with a diameter of 1.3 cm and a thickness of 0.3 cm, and then sintered at 550-600°C in a muffle furnace. After keeping warm for 4 hours, it is naturally cooled to room temperature to obtain vanadate K2MnV2O7.

[0083] Example 1

[0084] like Figure 2 As shown in the flow chart, the preparation method of the potassium manganese vanadate coated modified ternary positive electrode material described in this embodiment includes the following steps:

[0085] (1) Prepare the precursor Ni according to the conventional method 0.65 Co 0.07 Mn 0.28 (OH)2(D 50 4.2±0.3μm), Li2CO3(D 50 6±2μm) and dopant WO3(D 50 2.5±1.0μm), Y2O3(D 50 3.0±1.0μm), Zr 0.97 Y 0.03 O2(D 50 3.5±1.0μm), β-Al2O3(D50 The raw material was Ni 0.65 Co 0.07 Mn 0.28 (OH)2(4000g), Li2CO3(1688.214g), WO3(9.099g), Y2O3(3.051g), Zr 0.97 Y 0.03 O2(8.654g), β-Al2O3(9.081g); the materials were transferred into a high-speed mixer, and the three powders were mixed uniformly by using a four-stage mode of 100rmp / 2min, 400rmp / 2min, 1000rpm / 15min, and 100rmp / 3min. After loading into a crucible, the materials were transferred into a muffle furnace in an oxygen atmosphere, and sintered at a rate of 2℃ / min to 476℃ for 4.8h, then to 765℃ for 3.2h, and then to 948℃ for 11.0h. After cooling, crushing, sieving, and removing the magnet, a ternary positive electrode material doped substrate was obtained;

[0086] (2) 3800g of the obtained doped substrate was sampled and mixed with a coating agent K2MnV2O7(D 50 60.0±20.0nm) (13.781g), Zr 0.97 Y 0.03 O2(D 50 50.0±20.0nm) (3.083g), NbO2(D 50 30.0±20.0nm) (2.557g), TiO2(D 50 80.0±20.0nm) (3.175g) into a high-speed mixer, and mixed uniformly by using a three-stage mode of 100rmp / 2min, 1200rpm / 30min, and 200rmp / 3min. After loading into a crucible, the materials were sintered at 650℃ for 8.7h in an oxygen or oxygen empty (5:5) atmosphere. After cooling, crushing by a colloid mill, sieving, and removing the magnet, a positive electrode material coating substrate was obtained.

[0087] (3) 3700g of the obtained substrate was sampled and mixed with an additive Li2O6V2(D 50 80.0±20.0nm) (11.30g) and K2MnV2O7(D 50The three powders were mixed uniformly in a high-speed mixer in a three-stage mode of 100 rpm / 2 min, 1200 rpm / 30 min, and 200 rpm / 3 min, and then loaded into a crucible and sintered at 364 ℃ for 6.0 h in a dry air atmosphere. After cooling, the material was broken by a colloid mill and sieved to remove the magnetic substance. The obtained ternary positive electrode material was mixed in a batch mixing tank for 1.0 h, and then sieved to remove the magnetic substance and packaged to obtain the ternary positive electrode material product. The XRD characterization graph of the material prepared in Example 1 is shown in Figure 1 .

[0088] Example 2

[0089] The preparation method of the manganese potassium vanadate coated modified ternary positive electrode material in the present embodiment is shown in the flowchart as Figure 2 follows, and comprises the following steps:

[0090] (1) The precursor Ni 0.58 Co 0.07 Mn 0.35 (OH)2(D 50 4.2±0.3 μm), Li2CO3(D 50 6±2 μm), and the dopants WO3(D 50 2.5±1.0 μm), Y2O3(D 50 3.0±1.0 μm), Zr 0.97 Y 0.03 O2(D 50 3.5±1.0 μm), and β-Al2O3(D 50 4.0±1.0 μm) were prepared according to the conventional method. Ni 0.58 Co 0.07 Mn 0.35 (OH)2(4000 g), Li2CO3(1707.692 g), WO3(9.099 g), Y2O3(3.051 g), Zr 0.97 Y 0.03 O2(8.654 g), and β-Al2O3(9.081 g) were weighed. The materials were transferred into a high-speed mixer, and the three powders were mixed uniformly in a four-stage mode of 100 rpm / 2 min, 400 rpm / 2 min, 1000 rpm / 15 min, and 100 rpm / 3 min. After loading into a crucible, the materials were transferred into a muffle furnace in a micro-positive pressure oxygen atmosphere, and sintered at a rate of 2 ℃ / min to 476 ℃ for 4.8 h, then to 765 ℃ for 3.2 h, and then to 964 ℃ for 11.0 h. After cooling, the ternary positive electrode material doped substrate was obtained after being broken and sieved.

[0091] (2) The obtained doped substrate sample 3800 g is mixed with coating agent K2MnV2O7(D 50 to 60.0±20.0 nm) (11.944 g), Zr 0.97 Y 0.03 O2(D 50 to 50.0±20.0 nm) (3.083 g), NbO2(D 50 to 30.0±20.0 nm) (2.557 g), TiO2(D 50 to 80.0±20.0 nm) (3.175 g) into a high-speed mixer, and mixed uniformly in a three-stage mode of 100 rmp / 2 min, 1200 rpm / 30 min, and 200 rmp / 3 min. The three kinds of powders are then loaded into a crucible, sintered at 670°C for 8.7 h under an oxygen or oxygen empty (5:5) atmosphere, broken by a colloid mill after cooling, and sieved to remove magnetism, to obtain a positive electrode material coated substrate;

[0092] (3) The obtained substrate sample 3700 g is mixed with additives Li2O6V2(D 50 to 80.0±20.0 nm) (11.30 g) and K2MnV2O7(D 50 to 130±20.0 nm) (6.791 g) into a high-speed mixer, and mixed uniformly in a three-stage mode of 100 rmp / 2 min, 1200 rpm / 30 min, and 200 rmp / 3 min. The three kinds of powders are then loaded into a crucible, sintered at 364°C for 6.0 h under a dry air atmosphere, broken by a colloid mill after cooling, and sieved to remove magnetism. The obtained ternary positive electrode material is mixed in a batch mixing tank for 1.0 h, sieved to remove magnetism, packaged, and related physical and chemical data are tested.

[0093] Comparative Example 1

[0094] The preparation method of the positive electrode material in the present comparative example comprises the following steps:

[0095] (1) According to a conventional method, precursor Ni 0.65 Co 0.07 Mn 0.28 (OH)2(D 50 to 4.2±0.3 μm), Li2CO3(D 50 to 6±2 μm) and dopant WO3(D 50 to 2.5±1.0 μm), Y2O3(D 50 to 3.0±1.0 μm), Zr 0.97 Y 0.03 O2(D 50 to 3.5±1.0 μm), β-Al2O3(D 50The raw material is 4.0 ± 1.0 μm 0.65 Co 0.07 Mn 0.28 (OH)2(4000 g), Li2CO3(1688.214 g), WO3(9.099 g), Y2O3(3.051 g), Zr 0.97 Y 0.03 O2(8.654 g), β-Al2O3(9.081 g); the materials are transferred into a high-speed mixer, and the three powders are mixed uniformly by using a four-stage mode of 100 rmp / 2 min, 400 rmp / 2 min, 1000 rpm / 15 min, and 100 rmp / 3 min. After being loaded into a crucible, the materials are transferred into a muffle furnace in an oxygen atmosphere, and sintered at a rate of 2 ℃ / min to 476 ℃ for 4.8 h, then to 765 ℃ for 3.2 h, and then to 948 ℃ for 11.0 h. After cooling, the sintered product is crushed and sieved to obtain a ternary positive electrode material doped substrate;

[0096] (2) 3800 g of the obtained doped substrate is mixed with a coating agent Zr 0.97 Y 0.03 O2(D 50 50.0 ± 20.0 nm) (4.111 g), NbO2(D 50 30.0 ± 20.0 nm) (2.557 g), and TiO2(D 50 80.0 ± 20.0 nm) (6.349 g) in a high-speed mixer by using a three-stage mode of 100 rmp / 2 min, 1200 rpm / 30 min, and 200 rmp / 3 min. After the three powders are mixed uniformly, the mixture is loaded into a crucible, sintered at 670 ℃ for 9.0 h in an oxygen or oxygen-air (5:5) atmosphere, crushed by a colloid mill after cooling, and sieved to remove magnetism, thereby obtaining a positive electrode material coating substrate;

[0097] (3) 3700 g of the obtained substrate is mixed with an additive Li2O6V2(D 50 80.0 ± 20.0 nm) (17.410 g) in a high-speed mixer by using a three-stage mode of 100 rmp / 2 min, 1200 rpm / 30 min, and 200 rmp / 3 min. After the three powders are mixed uniformly, the mixture is loaded into a crucible, sintered at 364 ℃ for 6.0 h in a dry air atmosphere, crushed by a colloid mill after cooling, and sieved to remove magnetism. The obtained ternary positive electrode material is mixed in a batch mixing tank for 1.0 h, and then sieved to remove magnetism and packaged to obtain a ternary positive electrode material product, and relevant physical and chemical data are tested.

[0098] Comparative Example 2

[0099] The preparation method of the positive electrode material in the present comparative example comprises the following steps:

[0100] (1) Prepare the precursor Ni according to the conventional method 0.58 Co 0.07 Mn 0.35 (OH)2(D 50 4.2±0.3μm), Li2CO3(D 50 6±2μm) and dopant WO3(D 50 2.5±1.0μm), Y2O3(D 50 3.0±1.0μm), Zr 0.97 Y 0.03 O2(D 50 3.5±1.0μm), β-Al2O3(D 50 4.0±1.0μm) raw materials, weigh Ni 0.58 Co 0.07 Mn 0.35 (OH)2(4000g), Li2CO3(1707.692g), WO3(9.099g), Y2O3(3.051g), Zr 0.97 Y 0.03 O2 (8.654g), β-Al2O3 (9.081g); the materials were transferred to a high-speed mixer, and the three powders were evenly mixed using a four-stage mode of 100rmp / 2min, 400rmp / 2min, 1000rpm / 15min, and 100rmp / 3min. After being loaded into a crucible, the mixture was transferred to an atmosphere muffle furnace. In a slightly positive oxygen atmosphere, the temperature was increased to 476°C at a rate of 2°C / min and sintered for 4.8h, then increased to 765°C and sintered for 3.2h, and then increased to 964°C and sintered for 11.0h. After cooling, crushing and sieving, a ternary positive electrode material doped matrix was obtained;

[0101] (2) 3800 g of the obtained doped substrate was sampled and mixed with the coating agent Zr 0.97 Y 0.03 O2(D 50 50.0±20.0nm)(3.083g), NbO2(D 50 30.0±20.0nm)(2.557g), TiO2(D 50 80.0±20.0nm) (6.349g) was put into a high-speed mixer, and the three powders were mixed evenly at a three-stage mode of 100rpm / 2min, 1200rpm / 30min, and 200rpm / 3min. The three powders were then put into a crucible, and the temperature was raised to 680℃ and sintered for 9.0h in an oxygen or oxygen-air (5:5) atmosphere. After cooling, the powder was crushed by a colloid mill and then sieved to remove magnetism to obtain a positive electrode material coated matrix;

[0102] (3) The obtained substrate sample 3700 g is mixed with additive Li20 6V2(D 50 The three powders are put into a high-speed mixer, mixed uniformly in a three-stage mode of 100 rpm / 2 min, 1200 rpm / 30 min, and 200 rpm / 3 min, and then loaded into a crucible. Sintering is performed at 364°C for 6.0 h in a dry air atmosphere, and after cooling, the material is broken by a colloid mill and sieved to remove the magnetic substance. The obtained ternary positive electrode material is put into a batch mixing tank and mixed for 1.0 h. The material is discharged, sieved, and packaged to obtain the ternary positive electrode material product, and the relevant physical and chemical data are tested.

[0103] Experimental Example

[0104] 1. Physical and chemical indicators

[0105] The ternary positive electrode materials prepared in the above examples 1-2 and comparative examples 1-2 are analyzed for physical and chemical indicators using relevant equipment known to those skilled in the art, such as scanning electron microscopy, laser particle size instrument, and Swiss automatic titration instrument. The test results are shown in Table 1 below.

[0106] The SEM images of the ternary positive electrode material prepared in example 1-2 are shown in Figs. Figure 3 (a)-(b), respectively.

[0107] Table 1. Physical and chemical indicator results of ternary positive electrode materials of examples 1-2 and comparative examples 1-2

[0108]

[0109] It can be seen that the physical and chemical indicator test data of the Ni6507 and Ni5807 ternary positive electrode single crystal materials in example 1-2 show improved performance in tap density and residual alkali, and have better performance advantages.

[0110] 2. Cycle performance test

[0111] The positive electrode materials prepared in examples 1-2 and comparative examples 1-2 are prepared into lithium ion batteries using methods known to those skilled in the art (active material: PVDF: CNT: SP = 97.2: 1.1: 0.8: 0.9, solid content 73.5%), and the obtained positive electrode materials are assembled into button cells.

[0112] The first charge-discharge specific capacity (see Figs. Figure 4 (a)-(b)) and 0.2C / 0.5C / 1.0C / 2.0C rate discharge performance are tested using a blue light test system in a voltage range of 3.0-4.4V at 25°C and 0.1C. The results are shown in Table 2 below.

[0113] Table 2. Rate discharge performance test results

[0114]

[0115] And the above-mentioned 100 cycles of discharge 100 cycles of cycle retention rate under 1C charge and discharge conditions, the test results are shown in Figure 4 As shown in FIG. 1C, wherein, Figure 4 In (a) is the result of Example 1 and Comparative Example 1, (b) is the result of Example 2 and Comparative Example 2.

[0116] The finished product obtained from Example 1 and Comparative Example 1 was prepared into a soft package battery cell, and the normal temperature and high temperature cycle performance was evaluated, and the test results at different temperatures are shown in FIG. 2A and FIG. 2B. Figures 5-6 As shown in FIG. 2A and FIG. 2B, wherein, Figure 5 In (a) is the result of Example 1 and Comparative Example 1, (b) is the result of Example 2 and Comparative Example 2.

[0117] The cycle DCIR test data of the product in Example 1 is shown in Table 3.

[0118] Table 3 Cycle DCIR test results of the product in Example 1

[0119]

[0120] It can be seen that the ternary positive electrode material prepared based on the formula and process flow system of the potassium manganese vanadate coated modified ternary positive electrode material has low DCIR excellent performance and normal temperature and high temperature long cycle performance. Through the ternary positive electrode material prepared in Example 1, its capacity retention is more than 94% under 1C / 1C-100% DOD (2.75V-4.40V) for 1000 continuous normal temperature cycles, as shown in Figure 6 (a); the capacity retention is more than 90% for 1000 high temperature cycles, as shown in Figure 6 (b), the DCIR growth is low, which can effectively ensure the stability of the output power in the later cycle.

[0121] The above describes the embodiments of the present application in detail, and the principles and implementation modes of the present application are described by applying specific examples; the above description of the embodiments is only used to help understand the method of the present application and its core idea; at the same time, for those skilled in the art, according to the idea of the present application, the specific implementation mode and application range will be changed, and the above description of the present application should not be understood as a limitation.

Claims

1. A potassium manganese vanadate coating modified ternary positive electrode material, characterized in that, The positive electrode material has a general formula: LiNi x Co y Mn z W a Al b Y c Zr d Ti e Nb f V g K h O2, and x+y+z+a+b+c+d+e+f+g+h=1; and a preparation method of the material comprises the following steps: (1) take ternary positive electrode material precursor Ni x Co y Mn z (OH)2, lithium source material and dopant are mixed, and first sintering treatment is carried out to obtain a ternary positive electrode material doped matrix; (2) The ternary positive electrode material doped substrate in step (1) is mixed with a vanadium-containing potassium manganese acid coating agent, and a second sintering treatment is performed to obtain a ternary positive electrode material coated substrate; the vanadium-containing potassium manganese acid coating agent includes K2MnV2O7, Zr 0.97 Y 0.03 A mixture of O2, NbO2, and TiO2. (3) mixing the ternary positive electrode material coating matrix of step (2) with a vanadium-containing manganese potassium vanadate additive, and performing a third sintering treatment to obtain a vanadium-containing manganese potassium vanadate coated modified ternary positive electrode material, wherein the vanadium-containing manganese potassium vanadate additive comprises Li2O6V2 and K2MnV2O7. The dopant includes WO3, Y2O3, Zr 0.97 Y 0.03 A mixture of O2 and β-Al2O3.

2. The preparation method of the potassium manganese vanadate coated modified ternary positive electrode material according to claim 1, characterized in that, comprising the following steps: (1) take ternary positive electrode material precursor Ni x Co y Mn z (OH)2, lithium source material and dopant are mixed, and first sintering treatment is carried out to obtain a ternary positive electrode material doped matrix; (2) The ternary positive electrode material doped substrate in step (1) is mixed with a vanadium-containing potassium manganese acid coating agent, and a second sintering treatment is performed to obtain a ternary positive electrode material coated substrate; the vanadium-containing potassium manganese acid coating agent includes K2MnV2O7, Zr 0.97 Y 0.03 O2, NbO2, and a mixture of TiO2. (3) mixing the ternary positive electrode material coating matrix of step (2) with a vanadium-containing manganese potassium vanadate additive, and performing a third sintering treatment to obtain a vanadium-containing manganese potassium vanadate coated modified ternary positive electrode material, wherein the vanadium-containing manganese potassium vanadate additive comprises Li2O6V2 and K2MnV2O7.

3. The preparation method of the potassium manganese vanadate coating modified ternary positive electrode material according to claim 2, characterized in that, The molar ratio of the lithium source material to the dopant in step (1) is 1:(0.90-1.18):(0.002-0.10). x Co y Mn z (OH)2, the lithium source material to Li + count, the molar ratio of the dopant to the total amount of doping metal elements is 1:(0.90-1.18):(0.002-0.10).

4. The preparation method of the potassium manganese vanadate coating modified ternary positive electrode material according to claim 2, characterized in that, WO3, Y2O3, Zr 0.97 Y 0.03 O2 and β-Al2O3 in a mass ratio of (0.01-0.60):(0.01-0.30):(0.01-0.50):(0.01-0.50).

5. The preparation method of the potassium manganese vanadate coating modified ternary positive electrode material according to claim 2, characterized in that, The first sintering step in step (1) comprises: first heating to 400-580℃ under an oxygen-containing atmosphere for 2-8h, then second heating to 580-840℃ for 2-6h, and third heating to 740-1000℃ for 8-20h.

6. The preparation method of the potassium manganese vanadate coating modified ternary positive electrode material according to claim 2, characterized in that, In the step (2), the molar ratio of the ternary positive electrode material doped matrix to the vanadium-containing manganese potassium vanadate coating agent (based on the total amount of coating elements) is 1:(0.02-0.50).

7. The preparation method of the potassium manganese vanadate coating modified ternary positive electrode material according to claim 2, characterized in that, K2MnV2O7, Zr in vanadium-containing potassium manganese oxide coating agent 0.97 Y 0.03 mass ratio of O2, NbO2 and TiO2 is (0.01-0.75):(0.01-0.30):(0.01-0.20):(0.01-0.35).

8. The preparation method of the potassium manganese vanadate coating modified ternary positive electrode material according to claim 2, characterized in that, The second sintering in step (2) is calcination and heat preservation at 350-780℃ for 1-20h.

9. The preparation method of the potassium manganese vanadate coating modified ternary positive electrode material according to claim 2, characterized in that, The mass ratio of the positive electrode material coating matrix to the vanadium-containing manganese potassium vanadate additive is 100:(0.01-0.90).

10. Use of the vanadium-containing manganese potassium vanadate coated modified ternary positive electrode material of claim 1 or prepared by the method of any one of claims 2-9 for preparing a secondary battery positive electrode sheet or a secondary battery.

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