Long-circulation type ternary positive electrode material and preparation method and application thereof

Abstract

The invention provides a long-circulation type ternary positive electrode material as well as a preparation method and application thereof, and relates to the technical field of lithium ion batteries. The chemical formula of the long-circulation type ternary positive electrode material is Lia (NixCoyMn1-x-y) 1-b (M) b O2, x is larger than or equal to 0.5 and smaller than 1.0, y is larger than 0 and smaller than or equal to 0.30, a is larger than or equal to 0.96 and smaller than 1.16, and b is larger than 0 and smaller than or equal to 0.1. M is selected from a combination containing Zr, Al, Sr, Mg and B. The invention also provides a preparation method of the long-circulation ternary positive electrode material. The invention also provides an application of the long-circulation type ternary positive electrode material in a secondary battery positive electrode plate or a secondary battery. The long-circulation type ternary positive electrode material provided by the invention has a long-circulation characteristic under a high-voltage condition, and the specific discharge capacity, the first efficiency, the safety performance, the cycle performance, the power performance and the like of the long-circulation type ternary positive electrode material are obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and in particular to a long-cycle ternary cathode material, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid global development of current 3C digital products, power tools, and new energy vehicles, the demand for lithium-ion batteries continues to increase. However, the core factors affecting or restricting the development of ternary cathode materials are safety, long-cycle performance, and resource issues such as nickel, cobalt, and lithium. Among them, safety, range anxiety of lithium batteries, vehicle safety, and cost are crucial. At present, most cathode materials are difficult to fully balance range, energy density, and safety in battery application performance. Among them, high-voltage ternary materials have certain safety and cycle performance advantages compared with high-nickel materials. How to ensure the cycle performance of ternary cathode materials under high-voltage conditions is an urgent problem to be solved in the current cathode material and battery cell application fields. High-safety and long-cycle ternary cathode materials are beneficial to reducing their long-term cost problems, improving their competitive advantages, and diversifying market choices due to healthy market competition and development. Through research on various metal compounds and process methods, their composite modification and process optimization can improve the long-cycle performance of ternary cathode materials under high voltage.

[0003] The development trend of ternary cathode materials for new energy lithium batteries is high voltage, single crystallization, and high nickel content. The insufficient structural stability and safety problems brought about by high voltage are huge challenges currently faced. By using multi-element composite doping modification to improve structural stability, and at the same time improving the antioxidant property and surface phase defects of the particle surface under high voltage, constructing a surface gradient coating, a fast ion conductor, or a solid-state coating layer is beneficial to improving the safety performance, cycle performance, rate performance, specific capacity per gram, and first efficiency of high-voltage cathode materials. The aim is to design a ternary cathode material with high-voltage long-cycle characteristics. Summary of the Invention

[0004] The purpose of the present invention is to provide a long-cycle ternary cathode material, a preparation method thereof, and an application thereof. A variety of metal compounds are co-doped in a certain proportion, and then surface gradient coating is carried out with other metal compounds to form a surface fast ion solid electrolyte coating layer. The finished ternary cathode material has good physical and chemical properties and application performance. The ternary cathode material has long-cycle characteristics under high-voltage conditions, and its discharge specific capacity, first efficiency, safety performance, cycle performance, and power performance are significantly improved.

[0005] In order to achieve the above object of the present invention, the following technical solutions are adopted in the present invention:

[0006] The present invention first provides a long-cycle ternary cathode material, the chemical formula of which is Li a (Ni xCo y Mn 1-x-y ) 1-b (M) b O₂, where 0.5 ≤ x < 1.0, 0 < y ≤ 0.3, 0.96 ≤ a < 1.16, 0 < b ≤ 0.1;

[0007] The M is selected from the combination containing Zr, Al, Sr, Mg and B.

[0008] The present invention also provides a preparation method of the above long - cycle ternary cathode material, including the following steps:

[0009] Step 1: Mix the ternary cathode material precursor Ni x Co y Mn 1-x-y (OH)₂, a lithium source and a dopant, and then conduct the first sintering to obtain the cathode material core Li a (Ni x Co y Mn 1-x-y )(Sr c Al d Zr e Mg f )O₂; where 0.5 ≤ x < 1.0, 0 < y ≤ 0.30, 0 < c ≤ 0.0055, 0 < d ≤ 0.0065, 0 < e ≤ 0.01, 0 < f ≤ 0.004, and the dopant is a compound containing Sr, Zr, Al and Mg elements;

[0010] Step 2: Mix the cathode material core obtained in Step 1 with a first coating agent, and conduct the second sintering to obtain the first - coated cathode material. The first coating agent is a compound containing Zr, Al and B elements;

[0011] Step 3: Mix the first - coated cathode material obtained in Step 2 with a second coating agent, and conduct the third sintering to obtain the long - cycle ternary cathode material. The second coating agent is a compound containing B, Zr and Li elements.

[0012] Preferably, the molar ratio of the total amount of Ni, Co and Mn in the ternary cathode material precursor in Step 1, the molar amount of Li in the lithium source, and the total molar amount of Sr, Al, Zr and Mg in the dopant is 1:(0.96 - 1.16):(0.0006 - 0.026).

[0013] Preferably, the lithium source in Step 1 is selected from one or more of LiOH, LiOH·H₂O, Li₂CO₃, LiNO₃ or C₂H₃O₂Li;

[0014] The compound dopants containing Sr, Zr, Al, and Mg elements are selected from Al2MgO6Zr, Al2H2O9Zr3, Al2Zr3O9, SrCO3, MgCO3, Zr(CO3)2, MgO3Zr, SrO, MgO, ZrO2, Zr 0.92 O2Y 0.08 、Zr 0.97 O2Y 0.03 、ZrB2, Zr(OH)4, SrZrO3, SrCl2, ZrCl4, MgCl2, AlCl3, SrF2, ZrF4, AlF3, MgF2, Al2O3, Mg(OH)2, Al(OH)3, Zr(OH)4, Sr(OH)2, Zr(CH3COO)4, Mg(CH3COO)2, Al(CH3COO)3, C2H3O2Sr, LiAlH4, Al(BH4)3, AlB2, AlPO4, Al(H2PO4)3, B2O3, H3BO3, Li3ZrBO3, LiAlO2, Li2ZrO3, Li3BO3, LiBO2, Li2O, C2H3O2Li or LiOH, two or several of them.

[0015] Preferably, the first sintering step in step one includes: in an oxygen-containing atmosphere, first heating to 300 - 800 °C and keeping it at a constant temperature for 1.5 - 4.5 h, then heating to 700 - 1100 °C and keeping it at a constant temperature for 6 - 24 h, and controlling the heating rate to be 1 - 30 °C / min.

[0016] Preferably, the ratio of the total molar amount of Ni, Co, and Mn in the cathode material core in step two to the total molar amount of Zr, Al, and B in the first coating agent is 1:(0.0003 - 0.0130);

[0017] The compound containing Zr, Al, and B elements is a mixture of Al2Zr3O9, a - Al2O3, and B2O3.

[0018] Preferably, the second sintering step in step two includes: in an oxygen-containing atmosphere, heating to 380 - 740 °C and keeping it warm for 3 - 16 h, and controlling the heating rate to be 1 - 20 °C / h.

[0019] Preferably, the ratio of the total molar amount of Ni, Co, and Mn in the first-coated cathode material in step three to the total molar amount of B, Zr, and Li in the second coating agent is 1:(0.0002 - 0.0120);

[0020] The compound containing B, Zr, and Li is Li3ZrBO3, or a mixture or synthetic compound of one of Zr(CO3)2, Zr(OH)4, and ZrO2 and LiBO2 and Li2O.

[0021] Preferably, the third sintering step described in Step 3 includes: heating to 220-480 °C in an atmosphere containing dry air or a combination of oxygen and air, holding for 2-12 h, and controlling the heating rate to be 1-20 °C / h.

[0022] The present invention also provides the application of the above long-cycle ternary cathode material in a secondary battery cathode sheet or a secondary battery.

[0023] Advantages of the present invention

[0024] The present invention provides a long-cycle ternary cathode material, its preparation method and application. Compared with the prior art, on the basis of traditional nickel-cobalt-manganese materials, the present invention conducts co-doping modification with Al2MgO6Zr, SrZrO3, Sr(OH)2, and Al2Zr3O9 to inhibit cation mixing, increase the structural stability and mechanical strength under high voltage long cycles, improve the conductivity of the structural hierarchy, effectively promote particle growth, broaden the layer spacing, and enhance the ion migration ability during charge and discharge at high rates in long cycles; by utilizing the low melting point and catalytic reaction characteristics of Sr(OH)2, the reaction temperature conditions are reduced, effectively promoting the diffusion of Al2MgO6Zr, SrZrO3, and Al2Zr3O9, and the uniformity and effectiveness of diffusion can improve the structural and thermal stability of the nickel-cobalt-manganese ternary material.

[0025] For the long-cycle ternary cathode material of the present invention, co-doping modification is carried out with Al2MgO6Zr, SrZrO3, Sr(OH)2, and Al2Zr3O9, and through a solid-phase reaction by high-temperature sintering, Sr / Zr / Al / Mg form cation co-doping, effectively increasing the particle strength, improving the reversible capacity, reducing the side reactions at the interface between the active material and the electrolyte, reducing the solubility of manganese in the organic electrolyte, and effectively improving and enhancing the cycle performance of the material under high voltage; and it can broaden the ion channels and the interlayer distance, improve the discharge efficiency and rate capability of the material; improve the high-temperature electrochemical performance of the material, reduce the degree of Li / Ni mixing, and ensure the structural stability and application performance of long-cycle high-voltage battery products.

[0026] The long-cycle ternary cathode material of the present invention is further subjected to primary coating modification using Al2Zr3O9, a-Al2O3, and B2O3 as coating agents. Among them, by using a-Al2O3 and Al2Zr3O9 coatings, the corrosion resistance of the ternary cathode material surface against the electrolyte and the surface oxidation characteristics under high voltage are improved; by using the better heat resistance of Al2Zr3O9 than a-Al2O3, the thermal safety, high-temperature cycle, and storage performance of the material surface are further improved; by using the low melting point characteristics of B2O3, the surface diffusion and reaction of the additive are promoted, and the surface particle morphology can be effectively repaired, the surface conductivity is increased, and the cell impedance is reduced; at the same time, after the surface coating of Al2Zr3O9, a-Al2O3, and B2O3, they can react with the residual lithium on the surface under high-temperature solid-phase synthesis conditions to generate fast ion conductors or solid electrolyte layers such as Li3AlB2O6 and Li3ZrBO3, which can effectively improve the surface conductivity, ion migration ability, and corrosion resistance of the material surface against hydrofluoric acid, inhibit the generation and formation of microcracks, etc., and ensure the application performance of long-cycle high-voltage battery products.

[0027] The long-cycle ternary cathode material of the present invention is further subjected to secondary coating modification using Li3ZrBO3 or Zr(CO3)2 / Zr(OH)4 / ZrO2+LiBO2+Li2O as coating agents; among them, by using the solid electrolyte characteristics of Li3ZrBO3, the SEM morphology, ionic conductivity, and surface conductivity can be improved under suitable conditions; by using the low melting point characteristics of Zr(CO3)2 / Zr(OH)4, the surface reaction and diffusion effects can be better improved, promoting the formation of Li3ZrBO3 fast ion solid electrolyte conductors on the surface, which can effectively improve the surface conductivity, ion migration ability, etc. of the material, and constructing a double-gradient solid electrolyte coating layer can further effectively inhibit the surface oxygen defect phase and the corrosion resistance of the particle surface, further improve the high-temperature oxidation resistance, reduce the surface impedance, improve the surface electron conductivity, improve the first discharge efficiency and cycle performance, and ensure the application performance of long-cycle high-voltage battery products.

[0028] The long-cycle ternary cathode material of the present invention adopts a composite modification method of multi-element co-doping and coating. Through the combined action of composite co-doping of Sr / Zr / Al / Mg compounds, primary coating with Zr / B / Al compounds, and secondary coating with Li / Zr / B compounds, the Li / Ni mixing and particle surface energy band effects in the cathode material are effectively improved, and the structural stability, thermal stability, rate / cycle / storage performance of the long-cycle single-crystal ternary cathode material are enhanced, the specific capacity per gram and the first efficiency are increased, and it has the advantages of a more stable layered structure, higher electronic conductivity, better rate performance, long-cycle performance storage, and high specific capacity at low cost. The lithium-ion battery prepared from the ternary cathode material provided by the present invention has a high specific capacity per gram, rate performance, safety, and cycle performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic structural diagram of the ternary cathode material of the present invention;

[0030] Figure 2 It is a schematic diagram of the preparation process flow of the ternary cathode material of the present invention;

[0031] Figure 3 It is the SEM morphological characteristics of the ternary cathode material prepared in Examples 1-5;

[0032] Figure 4 It is a schematic diagram of the XRD characterization of the ternary cathode material prepared in Example 1 / 5; -

[0033] Figure 5 It is a schematic diagram of the charge-discharge curves of the ternary cathode material prepared in Examples 1-5;

[0034] Figure 6 It is a schematic diagram of the rate discharge curves of the ternary cathode material prepared in Examples 1-5;

[0035] Figure 7 It is a schematic diagram of the electrode structure of the positive electrode sheet in Example 1 and Comparative Example 1;

[0036] Figure 8 It is a schematic diagram of the cell structure in Example 1 and Comparative Example 1;

[0037] Figure 9 It is a schematic diagram of the cycle curves of the ternary cathode full cell prepared in Example 1 and Comparative Example 1.

[0038] In the figure, 1, inner core, 2, first coating layer, 3, second coating layer. DETAILED DESCRIPTION OF THE INVENTION

[0039] The present invention first provides a long-cycle ternary cathode material, the chemical formula of which is Li a (Ni x Co y Mn 1-x-y ) 1-b (M) b O2, where 0.5 ≤ x < 1.0, 0 < y ≤ 0.3, 0.96 ≤ a < 1.16, 0 < b ≤ 0.1;

[0040] The M is selected from the combination containing Zr, Al, Sr, Mg and B.

[0041] As Figure 1 shown, the long-cycle ternary cathode material of the present invention includes an inner core 1, and a first coating layer 2 and a second coating layer 3 on the surface of the inner core;

[0042] The general formula of the inner core is Li a(Ni x Co y Mn 1-x-y )(Sr c Al d Zr e Mg f )O₂; where 0.5 ≤ x < 1.0, 0 < y ≤ 0.3, 0 < c ≤ 0.0055, 0 < d ≤ 0.0065, 0 < e ≤ 0.01, 0 < f ≤ 0.004;

[0043] The general formula of the first coating layer is Zr x1 B y1 Al z1 O c1 , where x1 = 1.0 - 4.0, y1 = 1.0 - 3.0, z1 = 1.0 - 4.0, c1 = 1.0 - 9.0;

[0044] The general formula of the second coating layer is Li a1 Zr x2 B y2 O₃, where a1 = 1.0 - 10.0, x2 = 1.0 - 3.0, y2 = 1.0 - 3.0;

[0045] The present invention also provides a method for preparing the above long - cycle ternary cathode material, as Figure 2 shown, including the following steps:

[0046] Step 1: Mix the ternary cathode material precursor Ni x Co y Mn 1-x-y (OH)₂, a lithium source, and a dopant, and then perform the first sintering to obtain the cathode material core Li a (Ni x Co y Mn 1-x-y )(Sr c Al d Zr e Mg f )O₂; where 0.5 ≤ x < 1.0, 0 < y ≤ 0.30, 0 < c ≤ 0.0055, 0 < d ≤ 0.0065, 0 < e ≤ 0.01, 0 < f ≤ 0.004, and the dopant is a compound containing Sr, Zr, Al, and Mg elements;

[0047] Step 2: Mix the cathode material core obtained in Step 1 with the first coating agent and perform the second sintering to obtain the first - coated cathode material, and the first coating agent is a compound containing Zr, Al, and B elements;

[0048] Step 3: Mix the first-coated cathode material obtained in Step 2 with a second coating agent and perform a third sintering to obtain a long-cycle ternary cathode material. The second coating agent is a compound containing B, Zr, and Li elements.

[0049] According to the present invention, for the selection of the ternary cathode material precursor in Step 1, the particle size D of the small-particle ternary precursor 50 can be 1.4 - 5.6 μm, preferably 1.6 - 4.8 μm.

[0050] The lithium source is preferably selected from one or more of LiOH, LiOH·H2O, Li2CO3, LiNO3, or C2H3O2Li, and more preferably LiOH or Li2CO3. During application, the coarse-grained lithium source can be mechanically ground to 2 - 10 μm or a lithium source of this specification on the market can be selected, preferably 2 - 4 μm.

[0051] According to the present invention, the ratio of the total molar amount of Ni, Co, and Mn in the ternary cathode material precursor in Step 1, the molar amount of Li in the lithium source, and the total molar amount of Sr, Al, Zr, and Mg in the doping agent is preferably 1:(0.96 - 1.16):(0.0006 - 0.026), more preferably 1:(0.98 - 1.12):(0.001 - 0.024), and most preferably 1:(0.99 - 1.10):(0.0012 - 0.020).

[0052] According to the present invention, the compound containing Sr, Zr, Al, and Mg elements in Step 1 is preferably selected from Al2MgO6Zr, Al2H2O9Zr3, Al2Zr3O9, SrCO3, MgCO3, Zr(CO3)2, MgO3Zr, SrO, MgO, ZrO2, Zr 0.92 O2Y 0.08 、Zr 0.97 O2Y 0.03, two or more combinations of ZrB2, Zr(OH)4, SrZrO3, SrCl2, ZrCl4, MgCl2, AlCl3, SrF2, ZrF4, AlF3, MgF2, Al2O3, Mg(OH)2, Al(OH)3, Zr(OH)4, Sr(OH)2, Zr(CH3COO)4, Mg(CH3COO)2, Al(CH3COO)3, C2H3O2Sr, LiAlH4, Al(BH4)3, AlB2, AlPO4, Al(H2PO4)3, B2O3, H3BO3, Li3ZrBO3, LiAlO2, Li2ZrO3, Li3BO3, LiBO2, Li2O, C2H3O2Li or LiOH, more preferably a mixture of Al2MgO6Zr, SrZrO3, Sr(OH)2 and Al2Zr3O9;

[0053] Among them, the ternary cathode material precursor Ni x Co y Mn 1-x-y (OH)2 and the mass ratio of Al2MgO6Zr is preferably 100:(0.03 - 1.12), more preferably 100:(0.08 - 0.84), and most preferably 100:(0.12 - 0.56);

[0054] The ternary cathode material precursor Ni x Co y Mn 1-x-y (OH)2 and the mass ratio of SrZrO3 is preferably 100:(0.02 - 0.80), more preferably 100:(0.04 - 0.57), and most preferably 100:(0.06 - 0.38);

[0055] The ternary cathode material precursor Ni x Co y Mn 1-x-y (OH)2 and the mass ratio of Sr(OH)2 is preferably 100:(0.01 - 0.45), more preferably 100:(0.03 - 0.33), and most preferably 100:(0.05 - 0.23);

[0056] The ternary cathode material precursor Ni x Co y Mn 1-x-y (OH)2 and the mass ratio of Al2Zr3O9 is preferably 100:(0.02 - 1.16), more preferably 100:(0.05 - 0.88), and most preferably 100:(0.07 - 0.58);

[0057] The purity of the described Al2MgO6Zr ≥ 99.0%, and its D 50The particle size is 0.04 μm - 4.0 μm, preferably 0.1 μm - 3.0 μm, more preferably 0.4 μm - 2.5 μm; the purity of SrZrO3 ≥ 99.5%, and its D 50 The particle size is 0.05 μm - 5.0 μm, preferably 0.1 μm - 4.0 μm, more preferably 0.2 μm - 3.5 μm; the purity of Sr(OH)2 ≥ 99.0%, and its D 50 The particle size is 0.04 μm - 4.0 μm, preferably 0.06 μm - 3.5 μm, more preferably 0.3 μm - 3.0 μm; the purity of Al2Zr3O9 ≥ 99.0%, and its D 50 The particle size is 0.2 μm - 4.0 μm, preferably 0.4 μm - 3.0 μm, more preferably 0.5 μm - 2.5 μm.

[0058] According to the present invention, the mixing step in Step 1 preferably uses a ball mill or pot mill, a plow mixer or a high-speed mixer and other mixing equipment to mix the materials evenly, and then loads them into a small dry pot or a sagger, shakes them well and cuts them into pieces before the first sintering. The first sintering step preferably includes: in an oxygen-containing atmosphere (preferably the atmosphere is oxygen, with a concentration ≥ 95%), first heat up to 300 - 800 °C and keep it at a constant temperature for 1.5 - 4.5 h, then heat up to 700 - 1100 °C (preferably 720 - 1050 °C) and keep it warm for 6 - 24 h (preferably 8 - 16 h).

[0059] When the first sintering step is carried out in a muffle furnace or a tube furnace mode, the heating rate is preferably controlled at 1 - 5 °C / min, more preferably the heating rate is 2 - 4 °C / min, and most preferably the heating rate is 3 °C / min; when the first sintering step is carried out in an atmosphere roller hearth furnace or a rotary furnace mode, the heating rate is preferably controlled at 1 - 30 °C / h, more preferably the heating rate is 5 - 20 °C / h, and most preferably the heating rate is 10 °C / h.

[0060] After the first sintering, it is further subjected to coarse crushing, fine crushing, sieving, and demagnetization to obtain a ternary cathode material doped matrix (core) for subsequent coating. The particle size D50 of the ternary cathode material after crushing and sieving is preferably 1.4 - 5.6 μm, more preferably 1.6 - 4.6 μm.

[0061] According to the present invention, the ratio of the total molar amount of Ni, Co, and Mn in the cathode material core in Step 2 to the total molar amount of Zr, Al, and B in the first coating agent is preferably 1:(0.0003 - 0.0130);

[0062] The compound containing Zr, Al and B elements is preferably a mixture of Al2Zr3O9, α-Al2O3 and B2O3 for dry coating; or a dispersion of Al2Zr3O9, α-Al2O3 and B2O3 with a solid content of 40-50% for wet coating; the solvent is one or a mixture of water and ethanol;

[0063] The mass ratio of the cathode material core to Al2Zr3O9 is preferably 100:(0.02-0.80), more preferably 100:(0.05-0.70), and most preferably 100:(0.08-0.58);

[0064] The mass ratio of the cathode material core to α-Al2O3 is preferably 100:(0.01-0.60), more preferably 100:(0.04-0.50), and most preferably 100:(0.06-0.42);

[0065] The mass ratio of the cathode material core to B2O3 is preferably 100:(0.02-0.90), more preferably 100:(0.04-0.80), and most preferably 100:(0.06-0.70).

[0066] The purity of the Al2Zr3O9 is ≥99.0%, and its D 50 particle size is 100nm-200nm; the purity of α-Al2O3 is ≥99.9%, and its D 50 particle size is 80nm-160nm; the purity of B2O3 is ≥99.0%, and its D 50 particle size is 80nm-160nm.

[0067] According to the present invention, in the dry mixing and coating step, a mixing equipment such as a ball mill, a pot mill, a plowshare mixer or a high-speed mixer is used to mix the materials evenly, and then they are loaded into a small dry pot or a sagger, shaken well and cut into pieces, and then subjected to a second sintering.

[0068] According to the present invention, in the wet mixing and coating step, a stirring and dispersion tank or a water washing and dispersion machine is used to mix the materials evenly, and then the solvent is removed through a plate and frame filter press / centrifuge and a double-cone dryer, and then they are loaded into a small dry pot or a sagger, shaken well and cut into pieces, and then subjected to a second sintering.

[0069] According to the present invention, the second sintering step includes: in an oxygen-containing atmosphere (the preferred atmosphere is oxygen, with a concentration ≥95%), heating to 380-740°C (preferably 400-720°C, more preferably 420-700°C) and holding for 3-16h (preferably 4-14h, more preferably 5-12h);

[0070] When the second sintering step is carried out in the mode of a muffle furnace or a tube furnace, the heating rate is preferably controlled at 1-3 °C / min; when the second sintering step is carried out in the mode of an atmosphere roller hearth furnace or a rotary furnace, the heating rate is preferably controlled at 1-20 °C / h.

[0071] After the second sintering, it is crushed, sieved, and demagnetized to obtain the first-coated cathode material for subsequent coating.

[0072] According to the present invention, the ratio of the total molar amount of Ni, Co, and Mn in the first-coated cathode material described in step three to the total molar amount of B, Zr, and Li in the second coating agent is preferably 1:(0.0002-0.0120);

[0073] According to the present invention, the compound containing B, Zr, and Li described in step three is preferably Li3ZrBO3; or a mixture or synthetic compound of one of Zr(CO3)2, Zr(OH)4, and ZrO2 and LiBO2 and Li2O;

[0074] The mass ratio of the first-coated cathode material to Li3ZrBO3 is preferably 100:(0.02-1.10), more preferably 100:(0.04-0.80), and most preferably 100:(0.06-0.60);

[0075] The purity of the Li3ZrBO3 is ≥99.5%, and its D 50 particle size is 100 nm-400 nm;

[0076] The mass ratio of the first-coated cathode material to ZrO2 is preferably 100:(0.01-0.62), more preferably 100:(0.02-0.50), and most preferably 100:(0.03-0.42); the mass ratio of the first-coated cathode material to Zr(CO3)2 is preferably 100:(0.010-0.74), more preferably 100:(0.02-0.60), and most preferably 100:(0.03-0.46); the mass ratio of the first-coated cathode material to Zr(OH)4 is preferably 100:(0.010-0.80), more preferably 100:(0.02-0.62), and most preferably 100:(0.03-0.50);

[0077] The mass ratio of the first-coated cathode material to LiBO2 is preferably 100:(0.02-0.60), more preferably 100:(0.04-0.48), and most preferably 100:(0.08-0.40);

[0078] The mass ratio of the positive electrode material after the first coating to Li2O is preferably 100:(0.04-0.80), more preferably 100:(0.06-0.64), and most preferably 100:(0.08-0.50);

[0079] The purity of ZrO2 is ≥99.9%, and its D 50 Particle size 100nm-400nm; Zr(CO3)2 purity ≥99.5%, its D 50 Particle size 100nm-400nm; Zr(OH)4 purity ≥99.9%, its D 50 Particle size 100nm-400nm; LiBO2 purity ≥99.5%, its D 50 Particle size 60nm-200nm; Li2O purity ≥99.5%, its D 50 Particle size 60nm-200nm;

[0080] According to the present invention, the mixing step described in step three uses a ball mill or a pot mill, a plowshare mixer or a high-speed mixer to mix the materials evenly, and then put them into a small dry pot or a sagger, shake them evenly and cut them into pieces before sintering them for the third time.

[0081] According to the present invention, the third sintering step comprises: heating to 220-480°C (preferably 240-470°C, more preferably 260-460°C) and keeping warm for 2-12h (preferably 3-11h, more preferably 4-10h) in an atmosphere containing dry air or oxygen-air combination (preferably the atmosphere is oxygen, the concentration is ≥95%);

[0082] When the third sintering step is carried out in a muffle furnace or a tube furnace mode, the heating rate of the step is preferably controlled to be 1-5°C / min, more preferably 2-4°C / min, and most preferably 3°C / min;

[0083] When the third sintering step is carried out in an atmosphere roller kiln or rotary kiln mode, the heating rate of the step is preferably controlled to be 1-20°C / h, more preferably 5-15°C / h, and most preferably 10°C / h.

[0084] The cathode material after the second coating is crushed, sieved, demagnetized, and can be mixed evenly in a batch mixing tank, and a dry gas (dehydration and carbon dioxide removal) or an inert gas is introduced for protection; the batch mixing equipment can be a ribbon batch mixer or a high-speed mixer. The particle size D of the finished cathode material after the second coating is obtained. 50 1.6-4.6μm.

[0085] The present invention also provides an application of the above long-cycle ternary cathode material in the preparation of a secondary battery cathode plate or a secondary battery. The secondary battery preferably includes a lithium-ion battery.

[0086] The present invention also discloses a secondary battery cathode plate or a secondary battery prepared from the above long-cycle ternary cathode material prepared from the long-cycle ternary cathode material or the method.

[0087] The present invention will be further described below in conjunction with embodiments. It should be noted that the following embodiments are provided for illustrative purposes only and do not constitute a limitation on the scope of the present invention claimed.

[0088] Unless otherwise specified, the raw materials, reagents, methods, etc. used in the embodiments are all conventional raw materials, reagents, and methods in the art.

[0089] Example 1

[0090] A method for preparing a long-cycle ternary cathode material includes the following steps:

[0091] (1) According to the conventional method, prepare the precursor Ni 0.65 Co 0.07 Mn 028 (OH)2 (D 50 is 3.6 ± 0.5 μm), Li2CO3 (D 50 is 3.5 ± 1 μm) and the dopant SrZrO3 (D 50 is 2.0 ± 1.0 μm), Al2MgO6Zr (D 50 is 1.5 ± 0.5 μm), Sr(OH)2 (D 50 is 1.5 ± 0.5 μm), Al2Zr3O9 (D 50 is 1.5 ± 0.5 μm) raw materials. Weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000 g), Li2CO3 (846.54 g), SrZrO3 (4.063 g), Al2MgO6Zr (6.34 g), Sr(OH)2 (2.80 g), Al2Zr3O9 (5.82 g) respectively; transfer the materials into a high-speed mixer, and use the three-stage mode of 200 rmp / 2 min, 800 rpm / 20 min, 100 rmp / 3 min to make the powder evenly mixed. After loading into a crucible, transfer it to an atmosphere muffle furnace. Under an oxygen atmosphere, heat it at a rate of 2 °C / min to 380 °C for sintering for 2.4 h, then heat it to 766 °C for sintering for 2.4 h, and then heat it to 934 °C for sintering for 13.2 h; after cooling, crush and screen to obtain the cathode material doping matrix;

[0092] (2) Take 1600 g of the obtained doped matrix and put it into a high-speed mixer together with the coating agents Al2Zr3O9 (D 50 with a size of 140.0 ± 20.0 nm) (4.65 g), B2O3 (D 50 with a size of 120.0 ± 20.0 nm) (5.24 g), and α-Al2O3 (D 50 with a size of 120.0 ± 20.0 nm) (4.54 g). Mix the powders evenly according to the three-stage mode of 100 rmp / 2 min, 1200 rpm / 30 min, and 200 rmp / 3 min. After loading into a crucible, transfer it to an atmosphere muffle furnace and sinter at 520 °C for 7.8 h in an oxygen atmosphere. After cooling, crush and then sieve to remove magnetic substances to obtain the coated matrix of the cathode material;

[0093] (3) Take 1500 g of the obtained coated matrix and put it into a high-speed mixer together with the coating agent Li3ZrBO3 (D 50 with a size of 200.0 ± 20.0 nm) (4.03 g). Mix the powders evenly according to the three-stage mode of 100 rmp / 2 min, 1000 rpm / 30 min, and 200 rmp / 3 min. After loading into a crucible, transfer it to an atmosphere muffle furnace and sinter at 360 °C for 5.6 h in a dry air atmosphere. After cooling, crush and sieve to remove magnetic substances; Put the obtained ternary cathode material into a VC mixing tank and mix for 2 h. After discharging, sieve to remove magnetic substances and package to obtain the finished product of Li 1.045 (Ni 0.65 Co 0.07 Mn 0.28 ) 0.99 Sr 0.0014 Al 0.0036 Zr 0.0036 Mg 0.0004 B 0.001 O2 cathode material finished product. Based on this finished product, conduct relevant material physical and chemical property characterization and coin cell performance test analysis, and fabricate a soft-pack P116103322-61Ah full cell and conduct cycle performance test for this material finished product. Its cathode plate and cell structure are as Figure 7 、 8 shown.

[0094] Example 2

[0095] A preparation method of a long-cycle ternary cathode material, comprising the following steps:

[0096] (1) According to the conventional method, prepare the precursor Ni 0.65 Co 0.07 Mn 028 (OH)2 (D 50 with a size of 3.6 ± 0.5 μm), Li2CO3 (D 50 with a size of 3.5 ± 1 μm) and the dopant SrZrO3 (D50 is 2.0 ± 1.0 μm), Al2MgO6Zr(D 50 is 1.5 ± 0.5 μm), Sr(OH)2(D 50 is 1.5 ± 0.5 μm), Al2Zr3O9(D 50 is 1.5 ± 0.5 μm) raw materials, respectively weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000 g), Li2CO3 (846.54 g), SrZrO3 (4.063 g), Al2MgO6Zr (6.34 g), Sr(OH)2 (2.80 g), Al2Zr3O9 (5.82 g); Transfer the materials into a high-speed mixer, and use a three-stage mode of 200 rmp / 2 min, 800 rpm / 20 min, 100 rmp / 3 min to mix the powder evenly. After loading into a crucible, transfer it to an atmosphere muffle furnace. Under an oxygen atmosphere, heat it at a rate of 2 °C / min to 380 °C for sintering for 2.4 h, then heat it to 766 °C for sintering for 2.4 h, and then heat it to 934 °C for sintering for 13.2 h; After cooling, crush and screen to obtain the doped matrix of the cathode material;

[0097] (2) Take a sample of 1600 g of the obtained doped matrix and the coating agent Al2Zr3O9 (D 50 is 140.0 ± 20.0 nm) (4.65 g), B2O3 (D 50 is 120.0 ± 20.0 nm) (5.24 g), α-Al2O3 (D 50 is 120.0 ± 20.0 nm) (4.54 g) and put them into a high-speed mixer. Mix the powder evenly according to the three-stage mode of 100 rmp / 2 min, 1200 rpm / 30 min, 200 rmp / 3 min. After loading into a crucible, transfer it to an atmosphere muffle furnace. Heat it to 520 °C for sintering for 7.8 h under an oxygen atmosphere, cool it down, crush and screen to remove magnetism to obtain the coated matrix of the cathode material;

[0098] (3) Take a sample of 1500 g of the obtained coated matrix and the coating agent ZrO2 (D 50 is 200.0 ± 20.0 nm) (2.16 g), LiBO2 (D 50 is 120.0 ± 20.0 nm) (2.80 g), Li2O (D 50(1.73 g) with a size of 120.0 ± 20.0 nm was put into a high-speed mixer, and the powder was mixed evenly according to the three-stage mode of 100 rmp / 2 min, 1000 rpm / 30 min, and 200 rmp / 3 min. After being loaded into a crucible, it was transferred to an atmosphere muffle furnace and sintered at 360 °C for 5.6 h in a dry air atmosphere. After cooling, it was crushed and sieved to remove magnetism; the obtained ternary cathode material was put into a VC mixing tank and mixed for 2 h, and then the product was sieved to remove magnetism and packaged to obtain the Li 1.045 (Ni 0.65 Co 0.07 Mn 0.28 ) 0.99 Sr 0.0014 Al 0.0036 Zr 0.0036 Mg 0.0004 B 0.001 O2 cathode material finished product, and relevant physical and chemical property characterization tests and data analysis were carried out.

[0099] Example 3

[0100] A preparation method of a long-cycle ternary cathode material, comprising the following steps:

[0101] (1) According to the conventional method, prepare the precursors Ni 0.65 Co 0.07 Mn 028 (OH)2 (D 50 with a size of 3.6 ± 0.5 μm), Li2CO3 (D 50 with a size of 3.5 ± 1 μm) and the dopants SrZrO3 (D 50 with a size of 2.0 ± 1.0 μm), Al2MgO6Zr (D 50 with a size of 1.5 ± 0.5 μm), Sr(OH)2 (D 50 with a size of 1.5 ± 0.5 μm), Al2Zr3O9 (D 50 with a size of 1.5 ± 0.5 μm) raw materials, and respectively weigh Ni 0.65 Co 0.07 Mn 028(OH)2 (2000 g), Li2CO3 (846.54 g), SrZrO3 (4.063 g), Al2MgO6Zr (6.34 g), Sr(OH)2 (2.80 g), Al2Zr3O9 (5.82 g); Transfer the materials into a high-speed mixer, and use the three-stage mode of 200 rmp / 2 min, 800 rpm / 20 min, and 100 rmp / 3 min to mix the powder evenly. After loading into a crucible, transfer it into an atmosphere muffle furnace. Under an oxygen atmosphere, heat it at a rate of 2 °C / min to 380 °C for sintering for 2.4 h, then heat it to 766 °C for sintering for 2.4 h, and then heat it to 934 °C for sintering for 13.2 h; After cooling, crush and screen to obtain the doped matrix of the cathode material;

[0102] (2) Take a sample of 1600 g of the obtained doped matrix and the coating agent Al2Zr3O9 (D 50 with a size of 140.0 ± 20.0 nm) (4.65 g), B2O3 (D 50 with a size of 120.0 ± 20.0 nm) (5.24 g), α-Al2O3 (D 50 with a size of 120.0 ± 20.0 nm) (4.54 g) and put them into a high-speed mixer. According to the three-stage mode of 100 rmp / 2 min, 1200 rpm / 30 min, and 200 rmp / 3 min, mix the powder evenly. After loading into a crucible, transfer it into an atmosphere muffle furnace. Under an oxygen atmosphere, heat it to 520 °C for sintering for 7.8 h, cool it down, crush and screen to remove magnetism, and obtain the coated matrix of the cathode material;

[0103] (3) Take a sample of 1500 g of the obtained coated matrix and the coating agent Zr(CO3)2 (D 50 with a size of 200.0 ± 20.0 nm) (3.33 g), LiBO2 (D 50 with a size of 120.0 ± 20.0 nm) (2.25 g), Li2O (D 50 with a size of 120.0 ± 20.0 nm) (1.73 g) and put them into a high-speed mixer. According to the three-stage mode of 100 rmp / 2 min, 1000 rpm / 30 min, and 200 rmp / 3 min, mix the powder evenly. After loading into a crucible, transfer it into an atmosphere muffle furnace. Under a dry air atmosphere, sinter at 320 °C for 5.6 h, cool it down, crush and screen to remove magnetism; Put the obtained ternary cathode material into a VC mixing tank and mix for 2 h, discharge, screen and remove magnetism for packaging to obtain Li 1.045 (Ni 0.65 Co 0.07 Mn 0.28 ) 0.99 Sr 0.0014 Al 0.0036 Zr 0.0036 Mg 0.0004 B 0.001The finished product of the O2 cathode material was subjected to relevant physical and chemical property characterization tests and data analysis.

[0104] Example 4

[0105] A preparation method of a long-cycle ternary cathode material, comprising the following steps:

[0106] (1) According to the conventional method, prepare the precursor Ni 0.65 Co 0.07 Mn 028 (OH)2 (D 50 is 3.6 ± 0.5 μm), Li2CO3 (D 50 is 3.5 ± 1 μm) and the dopant SrZrO3 (D 50 is 2.0 ± 1.0 μm), Al2MgO6Zr (D 50 is 1.5 ± 0.5 μm), Sr(OH)2 (D 50 is 1.5 ± 0.5 μm), Al2Zr3O9 (D 50 is 1.5 ± 0.5 μm) raw materials, respectively weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000 g), Li2CO3 (846.54 g), SrZrO3 (4.063 g), Al2MgO6Zr (6.34 g), Sr(OH)2 (2.80 g), Al2Zr3O9 (5.82 g); transfer the materials into a high-speed mixer, and use the three-stage mode of 200 rmp / 2 min, 800 rpm / 20 min, 100 rmp / 3 min to make the powder evenly mixed. After loading into the crucible, transfer it to an atmosphere muffle furnace. Under an oxygen atmosphere, heat it at a rate of 2 °C / min to 380 °C and sinter for 2.4 h, then heat it to 766 °C and sinter for 2.4 h, and then heat it to 934 °C and sinter for 13.2 h; after cooling, crush and screen to obtain the cathode material doped matrix;

[0107] (2) Take 1600 g of the obtained doped matrix and the coating agent Al2Zr3O9 (D 50 is 140.0 ± 20.0 nm) (4.65 g), B2O3 (D 50 is 120.0 ± 20.0 nm) (5.24 g), α-Al2O3 (D 50 is 120.0 ± 20.0 nm) (4.54 g) and put them into a high-speed mixer. According to the three-stage mode of 100 rmp / 2 min, 1200 rpm / 30 min, 200 rmp / 3 min, make the powder evenly mixed. After loading into the crucible, transfer it to an atmosphere muffle furnace. Under an oxygen atmosphere, heat it to 520 °C and sinter for 7.8 h, cool it down, crush and screen to remove magnetism to obtain the cathode material coated matrix;

[0108] (3) Take 1500 g of the obtained coated matrix and put it into a high-speed mixer together with the coating agents Zr(OH)4 (D 50 with a size of 200.0 ± 20.0 nm) (3.30 g), LiBO2 (D 50 with a size of 120.0 ± 20.0 nm) (2.25 g), Li2O (D 50 with a size of 120.0 ± 20.0 nm) (1.73 g). Mix the powders evenly according to the three-stage mode of 100 rmp / 2 min, 1000 rpm / 30 min, and 200 rmp / 3 min. After loading into a crucible, transfer it to an atmosphere muffle furnace and sinter at 320 °C for 5.6 h in a dry air atmosphere. After cooling, crush and screen to remove magnetism. Put the obtained ternary cathode material into a VC mixing tank and mix for 2 h. After discharging, screen and remove magnetism and then package to obtain the finished product of Li 1.045 (Ni 0.65 Co 0.07 Mn 0.28 ) 0.99 Sr 0.0014 Al 0.0036 Zr 0.0036 Mg 0.0004 B 0.001 O2 cathode material, and conduct relevant physical and chemical property characterization tests and data analysis.

[0109] Example 5

[0110] A preparation method of a long-cycle ternary cathode material, comprising the following steps:

[0111] (1) According to the conventional method, prepare the precursors Ni 0.65 Co 0.07 Mn 028 (OH)2 (D 50 with a size of 3.6 ± 0.5 μm), Li2CO3 (D 50 with a size of 3.5 ± 1 μm) and the dopants SrZrO3 (D 50 with a size of 2.0 ± 1.0 μm), Al2MgO6Zr (D 50 with a size of 1.5 ± 0.5 μm), Sr(OH)2 (D 50 with a size of 1.5 ± 0.5 μm), Al2Zr3O9 (D 50 with a size of 1.5 ± 0.5 μm) raw materials. Weigh Ni 0.65 Co 0.07 Mn 028(OH)2 (2000 g), Li2CO3 (846.54 g), SrZrO3 (4.063 g), Al2MgO6Zr (6.34 g), Sr(OH)2 (2.80 g), Al2Zr3O9 (5.82 g); Transfer the materials into a high-speed mixer, and use a three-stage mode of 200 rmp / 2 min, 800 rpm / 20 min, and 100 rmp / 3 min to mix the powder evenly. After loading into a crucible, transfer it into an atmosphere muffle furnace. Under an oxygen atmosphere, heat it at a rate of 2 °C / min to 380 °C for sintering for 2.4 h, then heat it to 766 °C for sintering for 2.4 h, and then heat it to 934 °C for sintering for 13.2 h; After cooling, crush and screen to obtain the doped matrix of the cathode material;

[0112] (2) Take a sample of 1600 g of the obtained doped matrix and add it to an aqueous dispersion containing Al2Zr3O9 (D 50 with a size of 140.0 ± 20.0 nm) (4.65 g), B2O3 (D 50 with a size of 120.0 ± 20.0 nm) (5.24 g), α-Al2O3 (D 50 with a size of 120.0 ± 20.0 nm) (4.54 g) and a solid content of 40% into a stirring mixer, and stir and mix evenly according to the three-stage mode of 200 rmp / 5 min, 1000 rpm / 30 min, and 100 rmp / 5 min; Input it into a centrifuge for dehydration through a peristaltic pump, then dry and dehydrate it through a double-cone dryer. Finally, load it into a crucible and transfer it into an atmosphere muffle furnace. Under an oxygen atmosphere, heat it to 520 °C for sintering for 7.8 h, cool it down, crush and screen to remove magnetic substances to obtain the coated matrix of the cathode material;

[0113] (3) Take a sample of 1500 g of the obtained coated matrix and add it to the coating agent Li3ZrBO3 (D 50 with a size of 200.0 ± 20.0 nm) (4.03 g) into a high-speed mixer, and mix the powder evenly according to the three-stage mode of 100 rmp / 2 min, 1000 rpm / 30 min, and 200 rmp / 3 min. After loading into a crucible, transfer it into an atmosphere muffle furnace. Under a dry air atmosphere, sinter it at 360 °C for 5.6 h, cool it down, crush and screen to remove magnetic substances; Transfer the obtained ternary cathode material into a VC mixing tank and mix for 2 h, discharge, screen to remove magnetic substances and package to obtain the Li 1.045 (Ni 0.65 Co 0.07 Mn 0.28 ) 0.99 Sr 0.0014 Al 0.0036 Zr 0.0036 Mg 0.0004 B 0.001 O2 cathode material finished product, and conduct relevant physical and chemical property characterization tests and data analysis.

[0114] Comparative Example 1

[0115] It is different from Example 1 in that Al2Zr3O9 doping and co - coating are not used. The preparation method of its cathode material includes the following steps:

[0116] (1) According to the conventional method, prepare the precursors Ni 0.65 Co 0.07 Mn 028 (OH)2 (D 50 is 3.6 ± 0.5 μm), Li2CO3 (D 50 is 3.5 ± 1 μm) and the dopant SrZrO3 (D 50 is 2.0 ± 1.0 μm), Al2MgO6Zr (D 50 is 1.5 ± 0.5 μm), Sr(OH)2 (D 50 is 1.5 ± 0.5 μm) raw materials. Weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000 g), Li2CO3 (846.54 g), SrZrO3 (4.063 g), Al2MgO6Zr (6.34 g), Sr(OH)2 (2.80 g) respectively; transfer the materials into a high - speed mixer, and use the three - stage mode of 200 rmp / 2 min, 800 rpm / 20 min, 100 rmp / 3 min to mix the powders evenly. After loading into a crucible, transfer it to an atmosphere muffle furnace. Under an oxygen atmosphere, heat it at a rate of 2 °C / min to 380 °C for sintering for 2.4 h, then heat it to 766 °C for sintering for 2.4 h, and then heat it to 934 °C for sintering for 13.2 h; after cooling, crush and screen to obtain the doped matrix of the cathode material;

[0117] (2) Take 1600 g of the obtained doped matrix as a sample and mix it with the coating agent B2O3 (D 50 is 120.0 ± 20.0 nm) (5.24 g), α - Al2O3 (D 50 is 120.0 ± 20.0 nm) (4.54 g) in a high - speed mixer, and use the three - stage mode of 100 rmp / 2 min, 1200 rpm / 30 min, 200 rmp / 3 min to mix the powders evenly. After loading into a crucible, transfer it to an atmosphere muffle furnace. Under an oxygen atmosphere, heat it to 520 °C for sintering for 7.8 h, cool it down, crush and screen to remove magnetism to obtain the coated matrix of the cathode material;

[0118] (3) Take 1500 g of the obtained coated matrix as a sample and mix it with the coating agent Li3ZrBO3 (D 50(4.03 g) with a size of 200.0 ± 20.0 nm was put into a high-speed mixer, and the powder was mixed evenly according to the three-stage mode of 100 rmp / 2 min, 1000 rpm / 30 min, and 200 rmp / 3 min. After being loaded into a crucible, it was transferred to an atmosphere muffle furnace and sintered at 360 °C for 5.6 h in a dry air atmosphere. After cooling, it was crushed and sieved to remove magnetism. The obtained ternary cathode material was put into a VC mixing tank and mixed for 2 h. After discharging and sieving to remove magnetism, it was packaged to obtain the finished cathode material. Based on this finished product, relevant material physical and chemical property characterization and coin cell performance test analysis were carried out, and the soft-pack P116103322-61 Ah full battery was fabricated with this material finished product and its cycle performance was tested. The cathode sheet and cell structure are as Figure 7 、 8 shown.

[0119] Comparative Example 2

[0120] The difference from Example 1 is that Al2Zr3O9 doping and co - coating were not used, and Li3ZrBO3 was not used for secondary coating modification. The preparation method of its cathode material includes the following steps:

[0121] (1) According to the conventional method, prepare the precursor Ni 0.65 Co 0.07 Mn 028 (OH)2 (D 50 with a size of 3.6 ± 0.5 μm), Li2CO3 (D 50 with a size of 3.5 ± 1 μm), and the dopant SrZrO3 (D 50 with a size of 2.0 ± 1.0 μm), Al2MgO6Zr (D 50 with a size of 1.5 ± 0.5 μm), Sr(OH)2 (D 50 with a size of 1.5 ± 0.5 μm) raw materials. Weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000 g), Li2CO3 (846.54 g), SrZrO3 (4.063 g), Al2MgO6Zr (6.34 g), Sr(OH)2 (2.80 g) respectively. Transfer the materials into a high-speed mixer and mix the powder evenly by the three-stage mode of 200 rmp / 2 min, 800 rpm / 20 min, and 100 rmp / 3 min. After being loaded into a crucible, transfer it to an atmosphere muffle furnace. Under an oxygen atmosphere, heat it at a rate of 2 °C / min to 380 °C and sinter for 2.4 h, then heat it to 766 °C and sinter for 2.4 h, and then heat it to 934 °C and sinter for 13.2 h. After cooling and crushing and sieving, the doped matrix of the cathode material is obtained;

[0122] (2) Take 1600 g of the obtained doped matrix and the coating agent B2O3 (D 50with a size of 120.0 ± 20.0 nm (5.24 g), α-Al2O3 (D 50 with a size of 120.0 ± 20.0 nm (4.54 g) were put into a high-speed mixer, and the powders were mixed evenly according to the three-stage mode of 100 rmp / 2 min, 1200 rpm / 30 min, and 200 rmp / 3 min. After being loaded into a crucible, they were transferred to an atmosphere muffle furnace and sintered at 520 °C for 7.8 h in an oxygen atmosphere. After cooling, they were crushed and then sieved to remove magnetic substances, obtaining the positive electrode material-coated matrix;

[0123] (3) 1500 g of the obtained coated matrix was sampled, loaded into a crucible, and then transferred to an atmosphere muffle furnace. It was sintered at 360 °C for 5.6 h in a dry air atmosphere. After cooling, it was crushed and sieved to remove magnetic substances; the obtained ternary positive electrode material was put into a VC mixing tank and mixed for 2 h. After discharging and sieving to remove magnetic substances, it was packaged to obtain the finished positive electrode material, and relevant physical and chemical property characterization tests and data analysis were carried out.

[0124] Comparative Example 3

[0125] The difference from Example 1 is that Al2MgO6Zr and Al2Zr3O9 doping were not carried out. The preparation method of its positive electrode material includes the following steps:

[0126] (1) According to the conventional method, prepare the precursor Ni 0.65 Co 0.07 Mn 028 (OH)2 (D 50 with a size of 3.6 ± 0.5 μm), Li2CO3 (D 50 with a size of 3.5 ± 1 μm) and the dopant SrZrO3 (D 50 with a size of 2.0 ± 1.0 μm), Al2MgO6Zr (D 50 with a size of 1.5 ± 0.5 μm), Sr(OH)2 (D 50 with a size of 1.5 ± 0.5 μm), Al2Zr3O9 (D 50 with a size of 1.5 ± 0.5 μm) raw materials. Weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000 g), Li2CO3 (846.54 g), SrZrO3 (4.063 g), Sr(OH)2 (2.80 g); transfer the materials into a high-speed mixer, and use the three-stage mode of 200 rmp / 2 min, 800 rpm / 20 min, and 100 rmp / 3 min to mix the powders evenly. After being loaded into a crucible, transfer them to an atmosphere muffle furnace. Under an oxygen atmosphere, heat them at a rate of 2 °C / min to 380 °C and sinter for 2.4 h, then heat to 766 °C and sinter for 2.4 h, and then heat to 934 °C and sinter for 13.2 h; after cooling, crush and sieve to obtain the positive electrode material doped matrix;

[0127] (2) Take 1600 g of the obtained doped matrix and mix it with coating agents Al2Zr3O9 (D 50 is 140.0 ± 20.0 nm) (4.65 g), B2O3 (D 50 is 120.0 ± 20.0 nm) (5.24 g), α-Al2O3 (D 50 is 120.0 ± 20.0 nm) (4.54 g) and put them into a high-speed mixer. Mix the powders evenly according to the three-stage mode of 100 rmp / 2 min, 1200 rpm / 30 min, 200 rmp / 3 min. After loading into a crucible, transfer it to an atmosphere muffle furnace. Heat it up to 520 °C in an oxygen atmosphere and sinter for 7.8 h. After cooling, crush and then sieve to remove magnetism to obtain the coated matrix of the cathode material;

[0128] (3) Take 1500 g of the obtained coated matrix and mix it with coating agent Li3ZrBO3 (D 50 is 200.0 ± 20.0 nm) (4.03 g) and put them into a high-speed mixer. Mix the powders evenly according to the three-stage mode of 100 rmp / 2 min, 1000 rpm / 30 min, 200 rmp / 3 min. After loading into a crucible, transfer it to an atmosphere muffle furnace. Heat it up to 360 °C in a dry air atmosphere and sinter for 5.6 h. After cooling, crush and sieve to remove magnetism; Put the obtained ternary cathode material into a VC mixing tank and mix for 2 h. After discharging, sieve to remove magnetism and package to obtain the finished cathode material, and conduct relevant physical and chemical property characterization tests and data analysis.

[0129] Comparative Example 4

[0130] The difference from Example 1 is that no Al2MgO6Zr doping, Al2Zr3O9 doping and coating are carried out. The preparation method of its cathode material includes the following steps:

[0131] (1) According to the conventional method, prepare the precursors Ni 0.65 Co 0.07 Mn 028 (OH)2 (D 50 is 3.6 ± 0.5 μm), Li2CO3 (D 50 is 3.5 ± 1 μm) and dopants SrZrO3 (D 50 is 2.0 ± 1.0 μm), Sr(OH)2 (D 50 is 1.5 ± 0.5 μm) raw materials. Weigh Ni 0.65 Co 0.07 Mn 028(OH)2 (2000 g), Li2CO3 (846.54 g), SrZrO3 (4.063 g), Sr(OH)2 (2.80 g); Transfer the materials into a high-speed mixer, and use a three-stage mode of 200 rmp / 2 min, 800 rpm / 20 min, and 100 rmp / 3 min to mix the powder evenly. After loading into a crucible, transfer it into an atmosphere muffle furnace. Under an oxygen atmosphere, heat it at a rate of 2 °C / min to 380 °C for sintering for 2.4 h, then heat it to 766 °C for sintering for 2.4 h, and then heat it to 934 °C for sintering for 13.2 h; After cooling, crush and screen to obtain the doped matrix of the cathode material;

[0132] (2) Take a sample of 1600 g of the obtained doped matrix and the coating agent B2O3 (D 50 is 120.0 ± 20.0 nm) (5.24 g), α-Al2O3 (D 50 is 120.0 ± 20.0 nm) (4.54 g) and put them into a high-speed mixer. According to the three-stage mode of 100 rmp / 2 min, 1200 rpm / 30 min, and 200 rmp / 3 min, mix the powder evenly. After loading into a crucible, transfer it into an atmosphere muffle furnace. Under an oxygen atmosphere, heat it to 520 °C for sintering for 7.8 h, cool it down, crush and then screen to remove magnetism to obtain the coated matrix of the cathode material;

[0133] (3) Take a sample of 1500 g of the obtained coated matrix and the coating agent Li3ZrBO3 (D 50 is 200.0 ± 20.0 nm) (4.03 g) and put them into a high-speed mixer. According to the three-stage mode of 100 rmp / 2 min, 1000 rpm / 30 min, and 200 rmp / 3 min, mix the powder evenly. After loading into a crucible, transfer it into an atmosphere muffle furnace. Under a dry air atmosphere, sinter it at 360 °C for 5.6 h, cool it down, crush and screen to remove magnetism; Put the obtained ternary cathode material into a VC mixing tank and mix for 2 h, discharge, screen to remove magnetism and package to obtain the finished cathode material, and conduct relevant physical and chemical property characterization tests and data analysis.

[0134] Comparative Example 5

[0135] The difference from Example 1 is that no Al2MgO6Zr doping, Al2Zr3O9 doping / coating is carried out, and no secondary coating modification is carried out using Li3ZrBO3. The preparation method of its cathode material includes the following steps:

[0136] (1) According to the conventional method, prepare the precursor Ni 0.65 Co 0.07 Mn 028 (OH)2 (D 50 is 3.6 ± 0.5 μm), Li2CO3 (D 50is 3.5 ± 1 μm) and dopant SrZrO3 (D 50 is 2.0 ± 1.0 μm), Sr(OH)2 (D 50 is 1.5 ± 0.5 μm) raw materials, respectively weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000 g), Li2CO3 (846.54 g), SrZrO3 (4.063 g), Sr(OH)2 (2.80 g); Transfer the materials into a high-speed mixer, and use the three-stage mode of 200 rmp / 2 min, 800 rpm / 20 min, 100 rmp / 3 min to mix the powder evenly. After loading into the crucible, transfer it to an atmosphere muffle furnace. Under an oxygen atmosphere, heat it at a rate of 2 °C / min to 380 °C for sintering for 2.4 h, then heat it to 766 °C for sintering for 2.4 h, and then heat it to 934 °C for sintering for 13.2 h; After cooling, crush and screen to obtain the doped matrix of the positive electrode material;

[0137] (2) Take a sample of 1600 g of the obtained doped matrix and the coating agent B2O3 (D 50 is 120.0 ± 20.0 nm) (5.24 g), α-Al2O3 (D 50 is 120.0 ± 20.0 nm) (4.54 g) and put them into a high-speed mixer. According to the three-stage mode of 100 rmp / 2 min, 1200 rpm / 30 min, 200 rmp / 3 min, mix the powder evenly. After loading into the crucible, transfer it to an atmosphere muffle furnace. Under an oxygen atmosphere, heat it to 520 °C for sintering for 7.8 h, cool it down, crush and screen to remove magnetism to obtain the coated matrix of the positive electrode material;

[0138] (3) Take a sample of 1500 g of the obtained coated matrix, load it into the crucible, and then transfer it to an atmosphere muffle furnace. Sinter it at 360 °C for 5.6 h under a dry air atmosphere, cool it down, crush and screen to remove magnetism; Put the obtained ternary positive electrode material into a VC mixing tank and mix for 2 h, discharge, screen and remove magnetism for packaging to obtain the finished product of the positive electrode material, and conduct relevant physical and chemical property characterization tests and data analysis.

[0139] Comparative Example 6

[0140] The difference from Example 1 is that Sr(OH)2\Al2MgO6Zr doping and Al2Zr3O9 doping / coating are not carried out. The preparation method of its positive electrode material includes the following steps:

[0141] (1) According to the conventional method, prepare the precursor Ni 0.65 Co 0.07 Mn 028 (OH)2 (D 50 is 3.6 ± 0.5 μm), Li2CO3 (D 50with a size of 3.5 ± 1 μm) and dopant SrZrO3 (D 50 with a size of 2.0 ± 1.0 μm) raw materials, respectively weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000 g), Li2CO3 (846.54 g), SrZrO3 (4.063 g); Transfer the materials into a high-speed mixer, and use a three-stage mode of 200 rmp / 2 min, 800 rpm / 20 min, and 100 rmp / 3 min to mix the powder evenly. After loading into a crucible, transfer it to an atmosphere muffle furnace. Under an oxygen atmosphere, heat it at a rate of 2 °C / min to 380 °C for sintering for 2.4 h, then heat it to 766 °C for sintering for 2.4 h, and then heat it to 934 °C for sintering for 13.2 h; After cooling, crush and screen to obtain the doped matrix of the cathode material;

[0142] (2) Take a sample of 1600 g of the obtained doped matrix and coating agent B2O3 (D 50 with a size of 120.0 ± 20.0 nm) (5.24 g), α-Al2O3 (D 50 with a size of 120.0 ± 20.0 nm) (4.54 g) and put them into a high-speed mixer. According to the three-stage mode of 100 rmp / 2 min, 1200 rpm / 30 min, and 200 rmp / 3 min, mix the powder evenly. After loading into a crucible, transfer it to an atmosphere muffle furnace. Under an oxygen atmosphere, heat it to 520 °C for sintering for 7.8 h, cool it down, crush and screen to remove magnetism, and obtain the coated matrix of the cathode material;

[0143] (3) Take a sample of 1500 g of the obtained coated matrix and coating agent Li3ZrBO3 (D 50 with a size of 200.0 ± 20.0 nm) (4.03 g) and put them into a high-speed mixer. According to the three-stage mode of 100 rmp / 2 min, 1000 rpm / 30 min, and 200 rmp / 3 min, mix the powder evenly. After loading into a crucible, transfer it to an atmosphere muffle furnace. Under a dry air atmosphere, heat it to 360 °C for sintering for 5.6 h, cool it down, crush and screen to remove magnetism; Transfer the obtained ternary cathode material into a VC mixing tank and mix for 2 h, discharge, screen to remove magnetism and package to obtain the finished cathode material, and conduct relevant physical and chemical property characterization tests and data analysis.

[0144] Comparative Example 7

[0145] The difference from Example 1 is that Sr(OH)2\Al2MgO6Zr doping, Al2Zr3O9 doping / coating are not carried out, and Li3ZrBO3 is not used for secondary coating modification. The preparation method of its cathode material includes the following steps:

[0146] (1) According to the conventional method, prepare the precursor Ni 0.65 Co0.07 Mn 028 (OH)2(D 50 (with a size of 3.6 ± 0.5 μm), Li2CO3(D 50 (with a size of 3.5 ± 1 μm) and the dopant SrZrO3(D 50 (with a size of 2.0 ± 1.0 μm) raw materials, respectively weigh Ni 0.65 Co 0.07 Mn 028 (OH)2(2000 g), Li2CO3(846.54 g), SrZrO3(4.063 g); Transfer the materials into a high-speed mixer, and use the three-stage mode of 200 rmp / 2 min, 800 rpm / 20 min, and 100 rmp / 3 min to mix the powders evenly. After loading into a crucible, transfer it to an atmosphere muffle furnace. Under an oxygen atmosphere, heat it at a rate of 2 °C / min to 380 °C for sintering for 2.4 h, then heat it to 766 °C for sintering for 2.4 h, and then heat it to 934 °C for sintering for 13.2 h; After cooling, crush and screen to obtain the doped matrix of the cathode material;

[0147] (2) Take 1600 g of the obtained doped matrix as a sample and mix it with the coating agent B2O3(D 50 (with a size of 120.0 ± 20.0 nm)(5.24 g), α-Al2O3(D 50 (with a size of 120.0 ± 20.0 nm)(4.54 g) and put them into a high-speed mixer. Mix the powders evenly according to the three-stage mode of 100 rmp / 2 min, 1200 rpm / 30 min, and 200 rmp / 3 min. After loading into a crucible, transfer it to an atmosphere muffle furnace. Under an oxygen atmosphere, heat it to 520 °C for sintering for 7.8 h, cool it down, crush and screen to remove magnetism to obtain the coated matrix of the cathode material;

[0148] (3) Take 1500 g of the obtained coated matrix as a sample, load it into a crucible, and then transfer it to an atmosphere muffle furnace. Sinter it at 360 °C for 5.6 h under a dry air atmosphere, cool it down, crush and screen to remove magnetism; Put the obtained ternary cathode material into a VC mixing tank and mix it for 2 h, discharge, screen and remove magnetism for packaging to obtain the finished cathode material, and conduct relevant physical and chemical property characterization tests and data analysis.

[0149] Comparative Example 8

[0150] The difference from Example 1 is that no doping modification is carried out. The preparation method of its cathode material includes the following steps:

[0151] (1) According to the conventional method, prepare the precursor Ni 0.65 Co 0.07 Mn 028 (OH)2(D 50 (with a size of 3.6 ± 0.5 μm), Li2CO3(D 50Raw materials with a particle size of 3.5 ± 1 μm), respectively weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000 g), Li2CO3 (846.54 g); Transfer the materials into a high-speed mixer, and use the three-stage mode of 200 rmp / 2 min, 800 rpm / 20 min, and 100 rmp / 3 min to mix the powder evenly. After loading into a crucible, transfer it to an atmosphere muffle furnace. Under an oxygen atmosphere, heat it at a rate of 2 °C / min to 380 °C for sintering for 2.4 h, then heat it to 766 °C for sintering for 2.4 h, and then heat it to 934 °C for sintering for 13.2 h; After cooling, crush and screen to obtain the doped matrix of the cathode material;

[0152] (2) Take 1600 g of the obtained doped matrix and the coating agent Al2Zr3O9 (D 50 with a particle size of 140.0 ± 20.0 nm) (4.65 g), B2O3 (D 50 with a particle size of 120.0 ± 20.0 nm) (5.24 g), α-Al2O3 (D 50 with a particle size of 120.0 ± 20.0 nm) (4.54 g) and put them into a high-speed mixer. According to the three-stage mode of 100 rmp / 2 min, 1200 rpm / 30 min, and 200 rmp / 3 min, mix the powder evenly. After loading into a crucible, transfer it to an atmosphere muffle furnace. Under an oxygen atmosphere, heat it to 520 °C for sintering for 7.8 h, cool it down, crush and screen to remove magnetism, and obtain the coated matrix of the cathode material;

[0153] (3) Take 1500 g of the obtained coated matrix and the coating agent Li3ZrBO3 (D 50 with a particle size of 200.0 ± 20.0 nm) (4.03 g) and put them into a high-speed mixer. According to the three-stage mode of 100 rmp / 2 min, 1000 rpm / 30 min, and 200 rmp / 3 min, mix the powder evenly. After loading into a crucible, transfer it to an atmosphere muffle furnace. Under a dry air atmosphere, heat it to 360 °C for sintering for 5.6 h, cool it down, crush and screen to remove magnetism; Transfer the obtained ternary cathode material into a VC mixing tank and mix for 2 h, discharge, screen to remove magnetism and pack to obtain the finished cathode material, and conduct relevant physical and chemical property characterization tests and data analysis.

[0154] Comparative Example 9

[0155] The difference from Example 1 is that no primary coating modification is carried out. The preparation method of the cathode material includes the following steps:

[0156] (1) According to the conventional method, prepare the precursor Ni 0.65 Co 0.07 Mn 028 (OH)2 (D 50is 3.6 ± 0.5 μm), Li2CO3 (D 50 is 3.5 ± 1 μm) and dopant SrZrO3 (D 50 is 2.0 ± 1.0 μm), Al2MgO6Zr (D 50 is 1.5 ± 0.5 μm), Sr(OH)2 (D 50 is 1.5 ± 0.5 μm), Al2Zr3O9 (D 50 is 1.5 ± 0.5 μm) raw materials, respectively weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000 g), Li2CO3 (846.54 g), SrZrO3 (4.063 g), Al2MgO6Zr (6.34 g), Sr(OH)2 (2.80 g), Al2Zr3O9 (5.82 g); Transfer the materials into a high-speed mixer, and use the three-stage mode of 200 rmp / 2 min, 800 rpm / 20 min, 100 rmp / 3 min to mix the powder evenly. After loading into the crucible, transfer it into an atmosphere muffle furnace. Under an oxygen atmosphere, heat it at a rate of 2 °C / min to 380 °C for sintering for 2.4 h, then heat it to 766 °C for sintering for 2.4 h, and then heat it to 934 °C for sintering for 13.2 h; After cooling, crush and screen to obtain the doped matrix of the cathode material;

[0157] (2) Take 1600 g of the obtained doped matrix and put it into a high-speed mixer. Mix the powder evenly according to the three-stage mode of 100 rmp / 2 min, 1200 rpm / 30 min, 200 rmp / 3 min. After loading into the crucible, transfer it into an atmosphere muffle furnace. Heat it to 520 °C for sintering for 7.8 h under an oxygen atmosphere, cool it down, crush it, and then screen and remove magnetism to obtain the coated matrix of the cathode material;

[0158] (3) Take 1500 g of the obtained coated matrix and the coating agent Li3ZrBO3 (D 50 is 200.0 ± 20.0 nm) (4.03 g) and put it into a high-speed mixer. Mix the powder evenly according to the three-stage mode of 100 rmp / 2 min, 1000 rpm / 30 min, 200 rmp / 3 min. After loading into the crucible, transfer it into an atmosphere muffle furnace. Sinter it at 360 °C for 5.6 h under a dry air atmosphere, cool it down, crush it, and then screen and remove magnetism; Put the obtained ternary cathode material into a VC mixing tank and mix it for 2 h. After discharging, screen and remove magnetism and package it to obtain the finished cathode material, and conduct relevant physical and chemical property characterization tests and data analysis.

[0159] Comparative Example 10

[0160] The difference from Example 1 is that no secondary coating modification is carried out. The preparation method of its cathode material includes the following steps:

[0161] (1) Prepare the precursor Ni according to the conventional method 0.65 Co 0.07 Mn 028 (OH)2 (D 50 with a size of 3.6 ± 0.5 μm), Li2CO3 (D 50 with a size of 3.5 ± 1 μm) and the dopant SrZrO3 (D 50 with a size of 2.0 ± 1.0 μm), Al2MgO6Zr (D 50 with a size of 1.5 ± 0.5 μm), Sr(OH)2 (D 50 with a size of 1.5 ± 0.5 μm), Al2Zr3O9 (D 50 with a size of 1.5 ± 0.5 μm) raw materials. Weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000 g), Li2CO3 (846.54 g), SrZrO3 (4.063 g), Al2MgO6Zr (6.34 g), Sr(OH)2 (2.80 g), Al2Zr3O9 (5.82 g) respectively; transfer the materials into a high-speed mixer, and use the three-stage mode of 200 rmp / 2 min, 800 rpm / 20 min, 100 rmp / 3 min to mix the powders evenly. After loading into the crucible, transfer it to an atmosphere muffle furnace. Under an oxygen atmosphere, heat it at a rate of 2 °C / min to 380 °C for sintering for 2.4 h, then heat it to 766 °C for sintering for 2.4 h, and then heat it to 934 °C for sintering for 13.2 h; after cooling, crush and screen to obtain the doped matrix of the cathode material;

[0162] (2) Take 1600 g of the obtained doped matrix as a sample and the coating agent Al2Zr3O9 (D 50 with a size of 140.0 ± 20.0 nm) (4.65 g), B2O3 (D 50 with a size of 120.0 ± 20.0 nm) (5.24 g), α-Al2O3 (D 50 with a size of 120.0 ± 20.0 nm) (4.54 g) and put them into a high-speed mixer. Mix the powders evenly according to the three-stage mode of 100 rmp / 2 min, 1200 rpm / 30 min, 200 rmp / 3 min. After loading into the crucible, transfer it to an atmosphere muffle furnace. Heat it to 520 °C for sintering for 7.8 h under an oxygen atmosphere, cool it down, crush and screen to remove magnetism to obtain the coated matrix of the cathode material;

[0163] (3) Sampling 1500 g of the obtained coated matrix, loading it into a crucible, and then transferring it to an atmosphere muffle furnace. Sinter at 360 °C for 5.6 h in a dry air atmosphere. After cooling, crush and screen to remove magnetic substances. Put the obtained ternary cathode material into a VC mixing tank and mix for 2 h. After discharging, screen and remove magnetic substances, and then package to obtain the finished cathode material. Conduct relevant physical and chemical property characterization tests and data analysis.

[0164] Comparative Example 11

[0165] The difference from Example 1 is that doping and coating modification are not carried out. The preparation method of its cathode material includes the following steps:

[0166] (1) According to the conventional method, prepare the precursors Ni 0.65 Co 0.07 Mn 028 (OH)2 (D 50 is 3.6 ± 0.5 μm), Li2CO3 (D 50 is 3.5 ± 1 μm) raw materials. Weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000 g) and Li2CO3 (846.54 g) respectively. Transfer the materials into a high-speed mixer, and use the three-stage mode of 200 rmp / 2 min, 800 rpm / 20 min, and 100 rmp / 3 min to make the powder evenly mixed. Load it into a crucible and then transfer it to an atmosphere muffle furnace. In an oxygen atmosphere, heat up to 380 °C at a rate of 2 °C / min for sintering for 2.4 h, then heat up to 766 °C for sintering for 2.4 h, and then heat up to 934 °C for sintering for 13.2 h. After cooling, crush and screen to obtain the doped matrix of the cathode material;

[0167] (2) Sampling 1600 g of the obtained doped matrix and putting it into a high-speed mixer. Use the three-stage mode of 100 rmp / 2 min, 1200 rpm / 30 min, and 200 rmp / 3 min to make the powder evenly mixed. Load it into a crucible and then transfer it to an atmosphere muffle furnace. In an oxygen atmosphere, heat up to 520 °C for sintering for 7.8 h. After cooling, crush and screen again to remove magnetic substances to obtain the coated matrix of the cathode material;

[0168] (3) Sampling 1500 g of the obtained coated matrix, loading it into a crucible, and then transferring it to an atmosphere muffle furnace. Sinter at 360 °C for 5.6 h in a dry air atmosphere. After cooling, crush and screen to remove magnetic substances. Put the obtained ternary cathode material into a VC mixing tank and mix for 2 h. After discharging, screen and remove magnetic substances, and then package to obtain the finished cathode material. Conduct relevant physical and chemical property characterization tests and data analysis.

[0169] Experimental Example

[0170] 1. Physical and Chemical Indexes

[0171] The positive electrode materials prepared in the above Examples 1-5 and Comparative Examples 1-11 were respectively tested for elements and impurity content, etc. The physical and chemical indexes of the samples were analyzed by relevant equipment such as scanning electron microscope, laser particle size instrument, and Metrohm automatic titrator well-known to those skilled in the art. The test results are shown in Table 1 below.

[0172] The SEM images of the ternary positive electrode materials prepared in Examples 1-5 are respectively shown in Figure 3 (a)-(e) as shown below. Further, XRD characterization was carried out on the ternary positive electrode materials prepared in Example 1 and Example 5, and the characterization results are shown in Figure 4 . The physical and chemical index results of the ternary positive electrode materials in Examples 1-5 and Comparative Examples 1-11 are shown in Table 1.

[0173] Table 1

[0174]

[0175] It can be seen that through the test data of the basic physical and chemical indexes of the Ni6507 ternary positive electrode single crystal material in Examples 1-5, the relevant performance indexes such as tap density and residual alkali have been improved, and it has excellent performance advantages.

[0176] 2. Cycle performance test

[0177] Using the method well-known to those skilled in the art, the positive electrode materials prepared in Examples 1-5 and Comparative Examples 1-11 were made into lithium-ion batteries (active material: PVDF: CNT: SP = 97.2: 1.1: 0.8: 0.9, solid content 73.5%), and the obtained positive electrode materials were assembled into button cells.

[0178] Using a Blue-Energy test system, within the voltage range of 3.0 - 4.40 V, at 25°C and 0.1C condition, the initial charge-discharge specific capacity (shown in (a)-(e) in Figure 5 ) and the charge / discharge performance at 0.2C / 0.5C / 1.0C / 2.0C rates (shown in (a)-(e) in Figure 6 ) of Examples 1-5 were tested. The results are shown in Table 2 below.

[0179] Table 2

[0180]

[0181] The soft-pack P116103322-61Ah full cells of Example 1 and Comparative Example 1 were fabricated and their cycling performance was tested using a positive electrode electrochemical system (active material: PVDF: CNT: SP = 97.2: 1.1: 0.8: 0.9, solid content 73.5%). The negative electrode was artificial graphite and the separator was a wet separator. It can be seen that for Example 1, the room temperature cycle was 4431 weeks ≥ 88.54%, and the high temperature cycle was 2555 weeks ≥ 85.59%. For Comparative Example 1, the room temperature cycle was 2370 weeks ≥ 80.59%, and the high temperature cycle was 1403 weeks ≥ 83.89%. The cycling performance was significantly improved compared with the same period. The test results are shown in Figure 9 the figure shown.

[0182] It can be seen that the specific capacity per gram of the ternary positive electrode material prepared by the present invention has increased compared with the same period, and both the rate discharge performance and the cycling performance have been improved.

[0183] The above examples are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that: within the scope of the spirit and essence defined by the claims of the present invention, the technical solutions described in the foregoing examples may be modified, or some or all of the technical features may be equivalently replaced; and these modifications or replacements are still within the scope defined by the claims of the present invention.

Claims

1. A long-cycle ternary cathode material, characterized in that: Its chemical formula is Li a (Ni x Co y Mn 1-x-y ) 1-b (M) b O2, where 0.5≤x<1.0, 0<y≤0.30, 0.96≤a<1.16, 0<b≤0.1; The M is selected from the group consisting of Zr, Al, Sr, Mg and B.

2. The method for preparing the long-cycle ternary cathode material according to claim 1, characterized in that: The following steps are involved: Step 1: Ni x Co y Mn 1-x-y (OH)2, lithium source and dopant are mixed and sintered for the first time to obtain the positive electrode material core Li a (Ni x Co y Mn 1-x-y )(Sr c Al d Zr e Mg f )O2; wherein 0.5≤x<1.0, 0<y≤0.30, 0<c≤0.0055, 0<d≤0.0065, 0<e≤0.01, 0<f≤0.004, and the dopant is a compound containing Sr, Zr, Al and Mg elements; Step 2: Mixing the positive electrode material core obtained in step 1 with the first coating agent, and performing a second sintering to obtain a positive electrode material after first coating, wherein the first coating agent is a compound containing Zr, Al and B elements; Step three: Mix the first coated positive electrode material obtained in step two with the second coating agent, and perform a third sintering to obtain a long-cycle ternary positive electrode material, wherein the second coating agent is a compound containing B, Zr and Li elements.

3. The method for preparing the long-cycle ternary cathode material according to claim 1, characterized in that: The ratio of the total molar amount of Ni, Co, and Mn in the ternary positive electrode material precursor described in step 1, the molar amount of Li in the lithium source, and the total molar amount of Sr, Al, Zr, and Mg in the dopant is 1: (0.96-1.16): (0.0006-0.026).

4. The method for preparing the long-cycle ternary cathode material according to claim 1, characterized in that: The lithium source in step 1 is selected from one or more of LiOH, LiOH·H2O, Li2CO3, LiNO3 or C2H3O2Li; The compound dopant containing Sr, Zr, Al and Mg elements is selected from Al2MgO6Zr, Al2H2O9Zr3, Al2Zr3O9, SrCO3, MgCO3, Zr(CO3)2, MgO3Zr, SrO, MgO, ZrO2, Zr 0.92 O2Y 0.08 、Zr 0.97 O2Y 0.03 , ZrB2, Zr(OH)4, SrZrO3, SrCl2, ZrCl4, MgCl2, AlCl3, SrF2, ZrF4, AlF3, MgF2, Al2O3, Mg(OH)2, Al(OH)3, Zr(OH)4, Sr(OH)2, Zr(CH3COO)4, Mg(CH3COO)2, Al(CH3COO)3, C2H3O2Sr, LiAlH4, Al(BH4)3, AlB2, AlPO4, Al(H2PO4)3, B2O3, H3BO3, Li3ZrBO3, LiAlO2, Li2ZrO3, Li3BO3, LiBO2, Li2O, C2H3O2Li or LiOH.

5. The method for preparing the long-cycle ternary cathode material according to claim 1, characterized in that: The first sintering step described in step 1 includes: in an oxygen-containing atmosphere, first heating to 300-800°C and keeping the temperature constant for 1.5-4.5 hours, then heating to 700-1100°C and keeping the temperature constant for 6-24 hours, and controlling the heating rate to 1-30°C / min.

6. The method for preparing the long-cycle ternary cathode material according to claim 1, characterized in that: The ratio of the total molar amount of Ni, Co, and Mn in the positive electrode material core described in step 2 to the total molar amount of Zr, Al, and B in the first coating agent is 1: (0.0003-0.0130); The compound containing Zr, Al and B elements is a mixture of Al2Zr3O9, a-Al2O3 and B2O3.

7. The method for preparing the long-cycle ternary cathode material according to claim 1, characterized in that: The second sintering step described in step 2 includes: heating to 380-740° C. and keeping the temperature for 3-16 hours in an oxygen-containing atmosphere, and controlling the heating rate to 1-20° C. / h.

8. The method for preparing the long-cycle ternary cathode material according to claim 1, characterized in that: The ratio of the total molar amount of Ni, Co, and Mn in the positive electrode material after the first coating to the total molar amount of B, Zr, and Li in the second coating agent in step 3 is 1: (0.0002-0.0120); The compound containing B, Zr and Li is Li3ZrBO3, or one of Zr(CO3)2, Zr(OH)4 and ZrO2, and a mixture or a synthetic compound of LiBO2 and Li2O.

9. The method for preparing the long-cycle ternary cathode material according to claim 1, characterized in that: The third sintering step described in step 3 includes: heating to 220-480° C. and keeping the temperature for 2-12 hours in an atmosphere containing dry air or oxygen-air combination, and controlling the heating rate to be 1-20° C. / h.

10. Use of the long-cycle ternary positive electrode material according to claim 1 in a secondary battery positive electrode sheet or a secondary battery.

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