Low-cobalt high-voltage ternary positive electrode material and preparation method and application thereof

Abstract

The application provides a low-cobalt high-voltage ternary positive electrode material and a preparation method and application thereof, the low-cobalt high-voltage ternary positive electrode material is modified by a plurality of element compounds containing Sr / Zr / Al / Nb / Ti / W / B, and is coated by a compound containing Al / W / B for the first time and a compound containing Li for the second time, so that a double-layer coating and a surface layer fast ion conductor and a solid electrolyte coating layer are formed, and the structural stability and thermal stability, the first discharge capacity and efficiency, the rate capability, the cycle performance and the storage performance of the single-crystal high-voltage ternary positive electrode material under different voltage and power conditions are improved; the low-cobalt high-voltage ternary positive electrode material has the performance advantages of stable layered structure stability, higher safety, low impedance, high rate capability, high specific capacity and long cycle at >= 4.40 V.

Description

Technical Field

[0001] The present invention relates to the field of lithium-ion battery positive electrode raw materials and lithium-ion battery application technology, and in particular to a low-cobalt high-voltage ternary positive electrode material and a preparation method and application thereof. Background Art

[0002] With the current rapid global development of 3C digital products, power tools, and new energy vehicles, demand for lithium-ion batteries continues to increase. However, key factors influencing or constraining the development of lithium-ion batteries are resources such as nickel, cobalt, and lithium, with lithium resources being crucial for battery and vehicle costs. The difficulty in fully balancing battery life with energy density and safety significantly impacts high-voltage cathode materials. Research on various metal compounds and process methods suggests that composite modification and process optimization can enhance the performance of high-voltage ternary cathode materials.

[0003] The development trend of ternary positive electrode materials for new energy lithium batteries is high voltage, single crystal, and high nickel. The insufficient structural stability and safety issues brought about by high voltage are huge challenges currently faced. The use of multi-element composite doping modification can improve structural stability, while improving the oxidation resistance of the particle surface under high voltage and surface phase defects, and constructing surface gradient coating, fast ion conductor or solid coating layer, which is beneficial to improving the safety performance, cycle performance, rate performance, gram-to-weight capacity and first efficiency of high-voltage positive electrode materials. Summary of the Invention

[0004] One of the purposes of the present invention is to provide a low-cobalt, high-voltage ternary positive electrode material, which is co-doped with multiple metal compounds in a certain proportion and then gradient-coated with other metal compounds to form a surface fast ion solid electrolyte coating layer. The finished ternary positive electrode material has good physical, chemical and application properties. The low-cobalt ternary positive electrode material has significantly improved discharge specific capacity, initial efficiency, safety performance, cycle performance and power performance under high voltage conditions.

[0005] A second object of the present invention is to provide a method for preparing the above-mentioned low-cobalt high-voltage ternary positive electrode material.

[0006] A third object of the present invention is to provide an application of the above-mentioned low-cobalt high-voltage ternary positive electrode material in the preparation of a secondary battery positive electrode sheet or a secondary battery.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0008] In a first aspect, the present invention provides a low-cobalt high-voltage ternary cathode material, comprising a core, and a first coating layer and a second coating layer sequentially coated on the surface of the core;

[0009] The chemical formula of the low-cobalt high-voltage ternary cathode material is Li a (Nix Co y Mn 1-x-y )(M) b O2, where 0.5≤x<1.0, 0<y≤0.10, 0.96≤a<1.14, 0<b≤0.15;

[0010] The M is selected from one or more of Zr, Al, Ce, Sr, Mg, Ti, Si, La, Ba, Ta, W, Co, Nb, Cr, Mo, Re, Ru, Zn, Ca, Y, In, Sn, F, B, C, and P;

[0011] Preferably, M is selected from the combination of Sr, Zr, Al, Nb, Ti, W, B, and Ta.

[0012] The core formula is Li a (Ni x Co y Mn 1-x-y )(Sr c Al d Zr e Ti f Nb g W h B j )O2; wherein, 0<c≤0.008, 0<d≤0.008, 0<e≤0.008, 0<f≤0.0065, 0<g≤0.0065, 0<h≤0.004, 0<i≤0.008.

[0013] The first coating layer has the general formula W x1 B y1 Al z1 O c1 , where x1 = 0.5 ~ 2.0, y1 = 1.0 ~ 5.0, z1 = 1.0 ~ 2.0, c1 = 1.0 ~ 3.0;

[0014] The second coating layer has the general formula of Li a1 Ta x2 O3, where a1=0.5~4, x2=1.0~3.0.

[0015] The low-cobalt high-voltage ternary cathode material is prepared by the following method: a ternary cathode material precursor is co-doped with a compound dopant containing Sr / Zr / Al / Nb / Ti / W / B elements and subjected to a first sintering, and then crushed, screened and demagnetized to obtain a cathode material core Li a (Ni x Co y Mn 1-x-y )(Sr c Al d Zre Ti f Nb g W h B j )O2; wherein, 0<c≤0.008, 0<d≤0.008, 0<e≤0.008, 0<f≤0.0065, 0<g≤0.0065, 0<h≤0.004, 0<i≤0.008; and then the positive electrode material core is mixed with a first coating agent of a compound containing W / Al / B elements and sintered for a second time, and after crushing, screening and demagnetizing, the first coated positive electrode material is obtained; finally, the first coated positive electrode material is mixed with a second coating agent of a compound containing Ta / Li elements and sintered for a third time, and after crushing, screening and demagnetizing, the second coated positive electrode material is obtained.

[0016] It also has stable layered structure characteristics and excellent overall battery performance at ≥4.40V.

[0017] Specifically, the present invention provides a method for preparing the above-mentioned low-cobalt high-voltage ternary cathode material, comprising the following steps:

[0018] (1) Ni x Co y Mn 1-x-y (OH)2 (0.5≤x<1.0, 0<y≤0.10), lithium source, and compound dopant containing Sr / Zr / Al / Nb / Ti / W / B elements are mixed and sintered for the first time, and then crushed, sieved, and demagnetized to obtain the positive electrode material core Li a (Ni x Co y Mn 1-x-y )(Sr c Al d Zr e Ti f Nb g W h B j )O2;

[0019] (2) mixing the positive electrode material core with a first coating agent of a compound containing W / Al / B elements and performing a second sintering, and then crushing, screening, and demagnetizing to obtain a first coated positive electrode material;

[0020] (3) The positive electrode material after the first coating is mixed with the second coating agent containing Ta / Li compound and sintered for the third time, and then crushed, screened, demagnetized, and batch mixed to obtain the finished positive electrode material after the second coating.

[0021] Among them, the substances containing Zr, Al, Ce, Sr, Mg, Ti, Si, La, Ba, Ta, W, Co, Nb, Cr, Mo, Re, Ru, Zn, Ca, Y, In, Sn, F, B, C, and P in the raw materials are one or more metal oxides, hydroxides, or halides.

[0022] The following details are provided:

[0023] Step (1):

[0024] The selection of ternary cathode material precursor, the particle size D 50 It can be 1.5-6.4 μm, preferably 1.8-5.2 μm.

[0025] The lithium source is one or more selected from LiOH, LiOH·H2O, Li2CO3, LiNO3 or C2H3O2Li, preferably LiOH or Li2CO3. When used, the coarse lithium source particles can be mechanically ground to 2-10 μm or a lithium source of similar specifications on the market can be selected, preferably 3-5 μm.

[0026] In some embodiments, the ternary cathode material precursor Ni x Co y Mn 1-x-y The ratio of the total molar amount of Ni, Co, and Mn in (OH)2, the molar amount of Li in the lithium source, and the total molar amount of Sr, Nb, Al, Zr, Ti, W, and B in the dopant is 1: (0.96~1.14): (0.0004~0.026), preferably 1: (0.98~1.10): (0.0008-~0.024), and more preferably 1: (0.99~1.08): (0.001~0.022).

[0027] In some embodiments, the dopant containing Sr / Nb / Al / Zr / Ti / W / B elements is a mixture of γ-Al2O3, SrZrO3, TiNb2O7 and WB4;

[0028] Preferably, the ternary cathode material precursor Ni x Co y Mn 1-x-y The mass ratio of (OH)2 to γ-Al2O3 is 100:(0.02 to -0.80), preferably 100:(0.06 to 0.70), and more preferably 100:(0.08 to 0.60);

[0029] Preferably, the ternary cathode material precursor Ni x Co y Mn 1-x-yThe mass ratio of (OH)2 to SrZrO3 is 100:(0.03-0.90), preferably 100:(0.06-0.78), and more preferably 100:(0.08-0.64);

[0030] Preferably, the ternary cathode material precursor Ni x Co y Mn 1-x-y The mass ratio of (OH)2 to TiNb2O7 is 100:(0.015 to -0.82), preferably 100:(0.04 to 0.66), and more preferably 100:(0.06 to 0.58);

[0031] Preferably, the ternary cathode material precursor Ni x Co y Mn 1-x-y The mass ratio of (OH)2 to WB4 is 100:(0.01-0.70), preferably 100:(0.04-0.60), more preferably 100:(0.06-0.50);

[0032] Preferably, the purity of γ-Al2O3 is ≥99.9%, and its D 50 Particle size 0.04 μm to 6 μm, preferably 0.1 μm to 5 μm, more preferably 0.4 μm to 3 μm;

[0033] Preferably, the purity of SrZrO3 is ≥99.5%, and its D 50 Particle size 0.05 μm to 5.0 μm, preferably 0.1 μm to 4.0 μm, more preferably 0.2 μm to 3.5 μm;

[0034] Preferably, the purity of TiNb2O7 is ≥99.0%, and its D 50 Particle size 0.04 μm to 6.0 μm, preferably 0.06 μm to 5.0 μm, more preferably 0.3 μm to 3 μm;

[0035] Preferably, the purity of WB4 is ≥99.5%, and its D 50 The particle size is 0.2 μm to 5 μm, preferably 0.4 μm to 4 μm, and more preferably 0.5 μm to 2.5 μm.

[0036] In some embodiments, the mixing step uses a ball mill, 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, cut them into pieces, and then perform the first sintering.

[0037] In some embodiments, the first sintering step includes: heating to 700-1100° C. (preferably 720-1050° C., more preferably 740-980° C.) in an oxygen-containing atmosphere (preferably an oxygen atmosphere with a concentration of ≥95%) and holding the temperature for 8-24 hours (preferably 8-20 hours, more preferably 9-18 hours);

[0038] Preferably, when the first sintering step is carried out in a muffle furnace or a tube furnace mode, the heating rate is controlled to be 1-5°C / min, preferably 2-4°C / min, more preferably 3°C / min;

[0039] Preferably, when the first sintering step is carried out in an atmosphere roller kiln or rotary kiln mode, the heating rate is controlled to be 1-30°C / h, preferably 5-20°C / h, more preferably 10°C / h.

[0040] After the first sintering, the ternary positive electrode material doped matrix (core) is obtained through coarse crushing, fine crushing, screening and demagnetization for subsequent coating.

[0041] Preferably, the particle size D50 of the ternary positive electrode material after crushing and sieving is 2 to 6 μm, preferably 2.2 to 4.6 μm.

[0042] Step (2):

[0043] In some embodiments, the ratio of the total molar amount of Ni, Co, and Mn in the core of the positive electrode material to the total molar amount of W, Al, and B in the first coating agent is 1:(0.0004~0.0120), preferably 1:(0.0006~0.011), and more preferably 1:(0.0008~0.009).

[0044] In some embodiments, the first coating agent containing W / Al / B elements is a mixture of WB4, α-Al2O3 and H3BO3;

[0045] Preferably, the mass ratio of the positive electrode material core to WB4 is 100:(0.02-0.80), preferably 100:(0.05-0.70), more preferably 100:(0.08-0.58);

[0046] Preferably, the mass ratio of the positive electrode material core to α-Al2O3 is 100:(0.01-0.60), preferably 100:(0.04-0.50), more preferably 100:(0.06-0.42);

[0047] Preferably, the mass ratio of the positive electrode material core to H3BO3 is 100:(0.02-0.90), preferably 100:(0.04-0.80), and more preferably 100:(0.06-0.70).

[0048] Preferably, the purity of WB4 is ≥99.5%, and its D 50 Particle size 100nm~200nm;

[0049] Preferably, the purity of α-Al2O3 is ≥99.9%, and its D 50 Particle size 80nm~160nm;

[0050] Preferably, the purity of H3BO3 is ≥99.5%, and its D 50 Particle size 1500~3000 mesh;

[0051] In some embodiments, the mixing step uses a ball mill, 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, cut them into pieces, and then sinter them for the second time.

[0052] In some embodiments, the second sintering step includes: heating to 380-740° C. (preferably 400-720° C., more preferably 420-700° C.) in an oxygen-containing atmosphere (preferably an oxygen atmosphere with a concentration of ≥95%) and holding the temperature for 3-16 hours (preferably 4-14 hours, more preferably 5-12 hours);

[0053] Preferably, when the second sintering step is carried out in a muffle furnace or a tube furnace mode, the heating rate is controlled to be 1-3°C / min;

[0054] Preferably, when the second sintering step is carried out in an atmosphere roller kiln or a rotary kiln mode, the heating rate is controlled to be 1-20° C. / h.

[0055] Step (3):

[0056] In some embodiments, 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 Ta and Li in the second coating agent is 1:(0.0001~0.0100), preferably 1:(0.0003~0.009), and more preferably 1:(0.0005~0.0080).

[0057] In some embodiments, the Ta / Li-containing second coating agent includes Ta2O5 and anhydrous C2H3O2Li, or Ta(OH)5 and anhydrous LiOH;

[0058] Preferably, the mass ratio of the positive electrode material after the first coating to Ta2O5 is 100:(0.01-0.30), preferably 100:(0.03-0.24), more preferably 100:(0.05-0.20);

[0059] Preferably, the mass ratio of the first coated positive electrode material to anhydrous C2H3O2Li is 100:(0.04-1.50), preferably 100:(0.08-1.20), more preferably 100:(0.1-0.96);

[0060] Preferably, the purity of Ta2O5 is ≥99.9%, and the D50 of Ta2O5 is 100-400 nm. 50 Preferably, the purity of Ta2O5 is ≥99.9%, and the D50 of Ta2O5 is 100-400 nm.

[0061] Preferably, the purity of anhydrous C2H3O2Li is ≥99.9%, and the D50 of anhydrous C2H3O2Li is 60-150 nm. 50 Preferably, the purity of anhydrous C2H3O2Li is ≥99.9%, and the D50 of anhydrous C2H3O2Li is 60-150 nm.

[0062] Preferably, the purity of Ta2O5 is ≥99.9%, and the D50 of Ta2O5 is 100-400 nm.

[0063] Preferably, the mass ratio of the first coated positive electrode material to Ta(OH)5 is 100:(0.02-0.50), preferably 100:(0.07-0.42), more preferably 100:(0.1-0.38).

[0064] Preferably, the mass ratio of the first coated positive electrode material to anhydrous LiOH is 100:(0.02-0.70), preferably 100:(0.04-0.56), more preferably 100:(0.08-0.42).

[0065] Preferably, the purity of Ta(OH)5 is ≥99.0%, and the D50 of Ta(OH)5 is 100-400 nm. 50 Preferably, the purity of Ta(OH)5 is ≥99.0%, and the D50 of Ta(OH)5 is 100-400 nm.

[0066] Preferably, the purity of anhydrous LiOH is ≥99.5%, and the D50 of anhydrous LiOH is 600-150 nm. 50 Preferably, the purity of anhydrous LiOH is ≥99.5%, and the D50 of anhydrous LiOH is 600-150 nm.

[0067] In some embodiments, the mixing step uses a ball mill or jar mill, a ploughshare mixer or a high-speed mixer to mix the materials uniformly, and then the materials are loaded into a small dry pan or a die to be shaken, cut and subjected to the third sintering.

[0068] In some embodiments, the third sintering step comprises the following steps: heating to 220-480°C (preferably 240-470°C, more preferably 260-460°C) under an atmosphere containing dry air or oxygen and air (preferably the atmosphere is oxygen with a concentration of ≥95%), and then maintaining the temperature for 2-12 h (preferably 3-11 h, more preferably 4-10 h).

[0069] Preferably, when the third sintering step is carried out in a muffle furnace or a tube furnace mode, the heating rate of the step is controlled to be 1-5°C / min, preferably the heating rate is 2-4°C / min, more preferably the heating rate is 3°C / min.

[0070] Preferably, when the third sintering step is carried out in an atmosphere roller kiln or rotary kiln mode, the heating rate of the step is controlled to be 1-20°C / h, preferably 5-15°C / h, more preferably 10°C / h.

[0071] The positive electrode material after the second coating is crushed, screened, and 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.

[0072] Preferably, the particle size D of the finished positive electrode material after the second coating is 50 2.2~4.6μm.

[0073] In a third aspect, the present invention provides an application of the above-mentioned low-cobalt high-voltage ternary positive electrode material in the preparation of a secondary battery positive electrode sheet or a secondary battery.

[0074] Preferably, the secondary battery comprises a lithium-ion battery.

[0075] The present invention also discloses a secondary battery positive electrode sheet or a secondary battery prepared from the low-cobalt high-voltage ternary positive electrode material or the low-cobalt high-voltage ternary positive electrode material prepared by the method.

[0076] Technical effects:

[0077] The low-cobalt, high-voltage ternary positive electrode material described in the present invention is modified by co-doping γ-Al2O3, SrZrO3, TiNb2O7 and WB4 on the basis of traditional nickel-cobalt-manganese materials; they jointly inhibit cation mixing, increase structural stability and structural mechanical strength under high voltage, improve the conductivity of the structural hierarchy, effectively promote particle growth, and widen the interlayer spacing, thereby improving its charge and discharge ion migration ability under high voltage and high rate; the structure and thermal stability of the nickel-cobalt-manganese ternary material are further improved by using γ-Al2O3 with certain structural stability when treated at low temperature, utilizing its catalytic reaction characteristics and the structural evolution characteristics of transforming to a stable α phase at high temperature.

[0078] The low-cobalt, high-voltage ternary positive electrode material of the present invention is co-doped and modified with γ-Al2O3, SrZrO3, TiNb2O7 and WB4, and undergoes a high-temperature sintering solid-phase reaction to form a cation co-doping of Sr / Zr / Al / Nb / Ti / B / W, which effectively increases the particle strength and improves the reversible capacity, reduces the side reactions at the interface between the active material and the electrolyte, reduces the solubility of manganese in the organic electrolyte, and effectively improves the material's cycle performance under high voltage; it can also widen the ion channel and the interlayer distance, improve the material's discharge efficiency and rate capability; improve the material's high-temperature electrochemical performance, reduce the degree of Li / Ni mixing, and ensure the application performance of the battery product.

[0079] The low-cobalt, high-voltage ternary cathode material of the present invention is further modified by coating with WB4, a-Al2O3 and H3BO3 as coating agents. The coating with a-Al2O3 and WB4 improves the surface corrosion resistance of the ternary cathode material and the surface oxidation characteristics under high voltage. The low melting point of H3BO3 promotes the surface diffusion and reaction of the additives, effectively repairs the surface particle morphology, improves the surface conductivity, and reduces the battery cell impedance. At the same time, after the surface is coated with WB4, a-Al2O3 and H3BO3, they react with residual lithium on the surface under high-temperature solid-phase synthesis conditions to generate Li3AlB2O6 and Li2WO4 fast ion conductors, which can effectively improve the surface conductivity and ion migration ability of the material. The fast ion conductors and W, B and Al-containing compounds can improve the corrosion resistance of the particle surface against hydrofluoric acid, inhibit the generation and occurrence of microcracks, improve the high-temperature oxidation resistance, reduce the surface impedance, improve the surface electronic conductivity, improve the first discharge efficiency and cycle performance, and ensure the application performance of high-voltage battery products.

[0080] The low-cobalt high-voltage ternary positive electrode material of the present invention is further modified by secondary coating using Ta2O5 and anhydrous C2H3O2Li or Ta(OH)5 and anhydrous LiOH as coating agents; wherein, by utilizing the low melting point characteristics of C2H3O2Li and LiOH, the surface particle morphology can be repaired under appropriate conditions to improve SEM; at the same time, the surface reaction and diffusion effects of Ta2O5 or Ta(OH)5 are improved, and the surface generation of lithium tantalate-like fast ion solid electrolyte conductors can be promoted, which can effectively improve the surface conductivity and ion migration ability of the material, 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 electronic conductivity, improve the first discharge efficiency and cycle performance, and ensure the application performance of high-voltage battery products.

[0081] The low-cobalt, high-voltage ternary positive electrode material of the present invention adopts a composite modification method of multi-element co-doping and coating. Through the synergistic effect of composite synergistic doping with Sr / Zr / Al / Nb / Ti / B / W compounds, primary coating with W / B / Al compounds, and secondary coating with Li / Ta compounds, the Li / Ni mixed arrangement and particle surface energy band effect in the positive electrode material are effectively improved, the structural stability and thermal stability, rate / cycle / storage performance of the low-cobalt, high-voltage single crystal ternary positive electrode material are improved, the gram-specific capacity and first efficiency are improved, and the layered structure is more stable, the electronic conductivity is higher, the rate is better, the long cycle performance storage is better, and the low cost and high specific capacity are advantages. The lithium-ion battery prepared from the ternary positive electrode material provided by the present invention has a high gram-specific capacity, rate, safety and cycle performance.

[0082] The present invention has been described in detail above, but the above embodiments are merely illustrative in nature and are not intended to limit the present invention. In addition, the present invention is not limited by any theory described in the above prior art or invention summary or the following examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1 Schematic diagram of the structure of the ternary cathode material of the present invention;

[0084] Figure 2 Flow chart of the preparation process of the ternary cathode material of the present invention;

[0085] Figure 3 The SEM morphology characteristics of the ternary cathode material prepared in Example 1-2;

[0086] Figure 4 This is the XRD characterization diagram of the ternary cathode material prepared in Example 1;

[0087] Figure 5 The charge and discharge curves of the ternary cathode material prepared in Example 1-2;

[0088] Figure 6 This is a rate discharge curve diagram of the ternary cathode material prepared in Example 1-2;

[0089] Figure 7 This is the full battery cycle curve of the ternary positive electrode prepared in Example 1. DETAILED DESCRIPTION

[0090] The present invention will be further described below with reference to the examples. It should be noted that the following examples are provided for illustrative purposes only and do not constitute a limitation on the scope of protection claimed in the present invention.

[0091] Unless otherwise specified, the raw materials, reagents, methods, etc. used in the examples are conventional raw materials, reagents, and methods in the art.

[0092] Example 1

[0093] A method for preparing a low-cobalt high-voltage ternary cathode material comprises the following steps:

[0094] (1) Prepare the precursor Ni according to the conventional method 0.65 Co 0.07 Mn 028 (OH)2(D 50 3.4±0.5μm), Li2CO3(D 50 3.5±1μm) and dopant SrZrO3(D 50 2.0±1.0μm), TiNb2O7(D 502.0±1.0μm),γ-Al2O3(D 50 1.5±0.5μm), WB4(D 50 1.5±0.5μm) raw materials, weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000g), Li2CO3 (764.10g), SrZrO3 (7.87g), TiNb2O7 (8.30g), γ-Al2O3 (7.18g), WB4 (4.02g); the materials were transferred into a high-speed mixer, and the powders were evenly mixed using a three-stage mode of 200rmp / 2min, 800rpm / 20min, and 100rmp / 3min. After being loaded into a crucible, the powders were transferred into an atmosphere muffle furnace, and in an oxygen atmosphere, the temperature was increased to 320°C at a rate of 2°C / min and sintered for 3.2h, then increased to 770°C and sintered for 3.6h, and then increased to 952°C and sintered for 12.4h; after cooling, crushing and sieving, a positive electrode material doped matrix was obtained;

[0095] (2) 1600 g of the obtained doped matrix was sampled and coated with WB4 (D 50 140.0±20.0nm)(4.81g), H3BO3(D 50 2500 mesh) (5.54g), α-Al2O3 (D 50 120.0±20.0nm) (3.64g) was put into a high-speed mixer and the powder was mixed evenly in a three-stage mode of 100rpm / 2min, 1200rpm / 30min, and 200rpm / 3min. After being put into a crucible, it was transferred into an atmosphere muffle furnace and heated to 680℃ under an oxygen atmosphere for 8.6h. After cooling, it was crushed and sieved to remove magnetism to obtain a positive electrode material coated matrix;

[0096] (3) Take 1500g of the obtained coated substrate and mix it with the coating agent Ta2O5(D 50 200.0±20.0nm)(2.15g), C2H3O2Li(D 50 The obtained ternary positive electrode material was put into a VC mixing tank and mixed for 2 hours. The material was sieved, demagnetized and packaged to obtain the finished positive electrode material. The relevant physical and chemical performance characterization tests and data analysis were carried out.

[0097] Example 2

[0098] A method for preparing a low-cobalt high-voltage ternary cathode material comprises the following steps:

[0099] (1) Prepare the precursor Ni according to the conventional method 0.72 Co 0.05 Mn 0.23 (OH)2(D 50 3.0±0.5μm), LiOH·H2O(D 50 3.0±1μm) and dopant SrZrO3(D 50 2.0±1.0μm), TiNb2O7(D 50 2.0±1.0μm),γ-Al2O3(D 50 1.5±0.5μm), WB4(D 50 1.5±0.5μm) raw materials, weigh Ni 0.72 Co 0.05 Mn 0.23 (OH)2 (2000g), LiOH·H2O (870.0g), SrZrO3 (8.13g), TiNb2O7 (8.60g), γ-Al2O3 (7.94g), WB4 (4.41g); the materials were transferred to a high-speed mixer and the powders were evenly mixed using a three-stage mode of 200 rpm / 2min, 800 rpm / 20min, and 100 rpm / 3min. After being loaded into a crucible, the mixture was transferred to an atmosphere muffle furnace and heated to 320°C at a rate of 2°C / min in an oxygen atmosphere for sintering for 3.2h, then heated to 770°C for sintering for 3.6h, and then heated to 894°C for sintering for 11.0h; after cooling, crushing and sieving, a positive electrode material doped matrix was obtained;

[0100] (2) 1600 g of the obtained doped matrix was sampled and coated with WB4 (D 50 140.0±20.0nm)(4.97g), H3BO3(D 50 2500 mesh) (5.97g), α-Al2O3 (D 50 120.0±20.0nm) (3.78g) was put into a high-speed mixer and the powder was mixed evenly in a three-stage mode of 100rpm / 2min, 1200rpm / 30min, and 200rpm / 3min. After being put into a crucible, it was transferred into an atmosphere muffle furnace and heated to 670℃ under an oxygen atmosphere for 8.4h. After cooling, it was crushed and sieved to remove magnetism to obtain a positive electrode material coated matrix;

[0101] (3) Take 1500g of the obtained coated substrate and mix it with the coating agent Ta2O5(D 50 200.0±20.0nm)(2.15g), C2H3O2Li(D 50The obtained ternary positive electrode material was put into a VC mixing tank and mixed for 2 hours. The material was sieved, demagnetized and packaged to obtain the finished positive electrode material. The relevant physical and chemical performance characterization tests and data analysis were carried out.

[0102] Comparative Example 1

[0103] The difference from Example 1 is that WB4 doping and cooperative coating are not used. The preparation method of the positive electrode material includes the following steps:

[0104] (1) Prepare the precursor Ni according to the conventional method 0.65 Co 0.07 Mn 028 (OH)2(D 50 3.4±0.5μm), Li2CO3(D 50 3.5±1μm) and dopant SrZrO3(D 50 2.0±1.0μm), TiNb2O7(D 50 2.0±1.0μm),γ-Al2O3(D 50 1.5±0.5μm), raw materials, weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000g), Li2CO3 (764.10g), SrZrO3 (7.87g), TiNb2O7 (8.30g), γ-Al2O3 (7.18g); transfer the materials into a high-speed mixer, adopt a three-stage mode of 200rmp / 2min, 800rpm / 20min, 100rmp / 3min to mix the three powders evenly, put them into a crucible and transfer them into an atmosphere muffle furnace, in an oxygen atmosphere, heat to 320℃ at a rate of 2℃ / min and sinter for 3.2h, then heat to 770℃ and sinter for 3.6h, and then heat to 952℃ and sinter for 12.4h; after cooling, crushing and sieving, a ternary positive electrode material doped matrix is ​​obtained;

[0105] (2) 1600 g of the obtained doped matrix was sampled and mixed with the coating agent H3BO3 (D 50 2500 mesh) (5.54g), α-Al2O3 (D 50120.0±20.0nm) (3.64g) was put into a high-speed mixer and the three powders were evenly mixed in a three-stage mode of 100rpm / 2min, 1200rpm / 30min, and 200rpm / 3min. After being put into a crucible, it was transferred to an atmosphere muffle furnace and heated to 680℃ in an oxygen atmosphere for 8.6h. After cooling, it was crushed and sieved to remove magnetism to obtain a positive electrode material coated matrix;

[0106] (3) Take 1500g of the obtained coated substrate and mix it with the coating agent Ta2O5(D 50 200.0±20.0nm)(2.15g), C2H3O2Li(D 50 The obtained ternary positive electrode material was put into a VC mixing tank and mixed for 2 hours. The material was sieved, demagnetized and packaged to obtain the finished positive electrode material. The relevant physical and chemical performance characterization tests and data analysis were carried out.

[0107] Comparative Example 2

[0108] The difference from Example 1 is that WB4 doping and cooperative coating are not used, and no secondary coating modification is performed. The preparation method of the positive electrode material includes the following steps:

[0109] (1) Prepare the precursor Ni according to the conventional method 0.65 Co 0.07 Mn 028 (OH)2(D 50 3.4±0.5μm), Li2CO3(D 50 3.5±1μm) and dopant SrZrO3(D 50 2.0±1.0μm), TiNb2O7(D 50 2.0±1.0μm),γ-Al2O3(D 50 1.5±0.5μm), raw materials, weigh Ni 0.65 Co 0.07 Mn 028(OH)2 (2000g), Li2CO3 (764.10g), SrZrO3 (7.87g), TiNb2O7 (8.30g), γ-Al2O3 (7.18g); transfer the materials into a high-speed mixer, adopt a three-stage mode of 200rmp / 2min, 800rpm / 20min, 100rmp / 3min to mix the powders evenly, put them into a crucible and transfer them into an atmosphere muffle furnace, in an oxygen atmosphere, heat to 320℃ at a rate of 2℃ / min and sinter for 3.2h, then heat to 770℃ and sinter for 3.6h, and then heat to 952℃ and sinter for 12.4h; after cooling, crushing and sieving, a ternary positive electrode material doped matrix is ​​obtained;

[0110] (2) 1600 g of the obtained doped matrix was sampled and mixed with the coating agent H3BO3 (D 50 2500 mesh) (5.54g), α-Al2O3 (D 50 120.0±20.0nm) (3.64g) was put into a high-speed mixer and the three powders were mixed evenly in a three-stage mode of 100rpm / 2min, 1200rpm / 30min, and 200rpm / 3min. After being put into a crucible, it was transferred to an atmosphere muffle furnace and heated to 680℃ under an oxygen atmosphere for 8.6h. After cooling, it was crushed and sieved to remove magnetism to obtain a finished product coated with a positive electrode material;

[0111] (3) The obtained ternary positive electrode material is put into a VC mixing tank and mixed for 2 hours. The material is sieved and packaged to obtain the finished positive electrode material, and relevant physical and chemical performance characterization tests and data analysis are carried out.

[0112] Comparative Example 3

[0113] The difference from Example 1 is that SrZrO3 and WB4 doping is not performed. The preparation method of the positive electrode material includes the following steps:

[0114] (1) Prepare the precursor Ni according to the conventional method 0.65 Co 0.07 Mn 028 (OH)2(D 50 3.4±0.5μm), Li2CO3(D 50 3.5±1μm) and TiNb2O7(D 50 2.0±1.0μm),γ-Al2O3(D 50 1.5±0.5μm), raw materials, weigh Ni 0.65 Co 0.07 Mn 028(OH)2(2000g), Li2CO3(764.10g), SrZrO3(7.87g), TiNb2O7(8.30g), γ-Al2O3(7.18g); the material was transferred into a high-speed mixer, and the powder was mixed uniformly in a three-stage mode of 200 rpm / 2 min, 800 rpm / 20 min, and 100 rpm / 3 min. After loading into a crucible, it was transferred into a muffle furnace in an oxygen atmosphere, and sintered at a rate of 2°C / min to 320°C for 3.2 h, then to 770°C for 3.6 h, and then to 952°C for 12.4 h. After cooling, crushing, and sieving, a ternary positive electrode material doped substrate was obtained.

[0115] (2) 1600 g of the obtained doped substrate was mixed with coating agent WB4(D 50 140.0±20.0 nm)(4.81g), H3BO3(D 50 2500 mesh)(5.54g), α-Al2O3(D 50 120.0±20.0 nm)(3.64g) in a high-speed mixer, and the powder was mixed uniformly in a three-stage mode of 100 rpm / 2 min, 1200 rpm / 30 min, and 200 rpm / 3 min. After loading into a crucible, it was transferred into a muffle furnace in an oxygen atmosphere, and sintered at 680°C for 8.6 h. After cooling, crushing, and sieving, a positive electrode material coated substrate was obtained.

[0116] (3) 1500 g of the obtained coated substrate was mixed with coating agent Ta2O5(D 50 200.0±20.0 nm)(2.15g), C2H3O2Li(D 50 80.0±10.0 nm)(7.64g) in a high-speed mixer, and the powder was mixed uniformly in a three-stage mode of 100 rpm / 2 min, 1000 rpm / 30 min, and 200 rpm / 3 min. After loading into a crucible, it was transferred into a muffle furnace in a dry air atmosphere, and sintered at 340°C for 6.4 h. After cooling, crushing, and sieving, a ternary positive electrode material was obtained. The ternary positive electrode material was mixed in a VC mixing tank for 2 h, sieved, and magnetically separated to obtain a positive electrode material product. The product was subjected to related physical and chemical performance characterization tests and data analysis.

[0117] Comparative Example 4

[0118] The difference between Example 1 and Comparative Example 4 is that no SrZrO3 doping and WB4 coating are performed. The preparation method of the positive electrode material comprises the following steps:

[0119] (1) According to the conventional method, the precursor Ni 0.65 Co 0.07 Mn 028 (OH)2(D50 3.4±0.5μm), Li2CO3(D 50 3.5±1μm) and dopant TiNb2O7(D 50 2.0±1.0μm), γ-Al2O3(D 50 1.5±0.5μm), WB4(D 50 1.5±0.5μm) raw materials, respectively, Ni 0.65 Co 0.07 Mn 028 (OH)2(2000g), Li2CO3(764.10g), TiNb2O7(8.30g), γ-Al2O3(7.18g), WB4(4.02g); the material was transferred into a high-speed mixer, and three-stage mode 200rmp / 2min, 800rpm / 20min, 100rmp / 3min was adopted to mix the powders uniformly, and then the powders were loaded into a crucible and transferred into a gas atmosphere muffle furnace, and then the temperature was raised to 320°C at a rate of 2°C / min under oxygen atmosphere, and then sintered for 3.2h, and then the temperature was raised to 770°C and sintered for 3.6h, and then the temperature was raised to 952°C and sintered for 12.4h; after cooling, the positive electrode material doped matrix was obtained after crushing and sieving;

[0120] (2) 1600g of the obtained doped matrix was mixed with coating agent H3BO3(D 50 2500 mesh)(5.54g), α-Al2O3(D 50 120.0±20.0nm)(3.64g) in a high-speed mixer, and three-stage mode 100rmp / 2min, 1200rpm / 30min, 200rmp / 3min was adopted to mix the three kinds of powders uniformly, and then the powders were loaded into a crucible and transferred into a gas atmosphere muffle furnace, and then the temperature was raised to 680°C and sintered for 8.6h under oxygen atmosphere, and then crushed and sieved to remove magnetism after cooling, and then the positive electrode material coated matrix was obtained;

[0121] (3) 1500g of the obtained coated matrix was mixed with coating agent Ta2O5(D 50 200.0±20.0nm)(2.15g), C2H3O2Li(D 50 80.0±10.0nm)(7.64g) in a high-speed mixer, and three-stage mode 100rmp / 2min, 1000rpm / 30min, 200rmp / 3min was adopted to mix the three kinds of powders uniformly, and then the powders were loaded into a crucible and transferred into a gas atmosphere muffle furnace, and then the temperature was raised to 340°C and sintered for 6.4h under dry air atmosphere, and then crushed and sieved to remove magnetism after cooling; the obtained ternary positive electrode material was put into a VC mixing tank and mixed for 2h, and then sieved and magnetism-removed to obtain the positive electrode material finished product, and then related physical and chemical performance characterization tests and data analysis were carried out.

[0122] Comparative Example 5

[0123] The difference from Example 1 is that no SrZrO3 doping and WB4 doping / coating were performed. The preparation method of the positive electrode material includes the following steps:

[0124] (1) Prepare the precursor Ni according to the conventional method 0.65 Co 0.07 Mn 028 (OH)2(D 50 3.4±0.5μm), Li2CO3(D 50 3.5±1μm) and dopant TiNb2O7(D 50 2.0±1.0μm),γ-Al2O3(D 50 1.5±0.5μm) raw materials, weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000g), Li2CO3 (764.10g), TiNb2O7 (8.30g), γ-Al2O3 (7.18g); transfer the materials into a high-speed mixer, adopt a three-stage mode of 200rpm / 2min, 800rpm / 20min, 100rpm / 3min to mix the powders evenly, put them into a crucible and transfer them into an atmosphere muffle furnace, in an oxygen atmosphere, heat to 320℃ at a rate of 2℃ / min and sinter for 3.2h, then heat to 770℃ and sinter for 3.6h, and then heat to 952℃ and sinter for 12.4h; after cooling, crushing and sieving, obtain a positive electrode material doped matrix;

[0125] (2) 1600 g of the obtained doped matrix was sampled and mixed with the coating agent H3BO3 (D 50 2500 mesh) (5.54g), α-Al2O3 (D 50 120.0±20.0nm) (3.64g) was put into a high-speed mixer and the powder was mixed evenly in a three-stage mode of 100rpm / 2min, 1200rpm / 30min, and 200rpm / 3min. After being put into a crucible, it was transferred into an atmosphere muffle furnace and heated to 680℃ under an oxygen atmosphere for 8.6h. After cooling, it was crushed and sieved to remove magnetism to obtain a positive electrode material coated matrix;

[0126] (3) Take 1500g of the obtained coated substrate and mix it with the coating agent Ta2O5(D 50 200.0±20.0nm)(2.15g), C2H3O2Li(D 50The obtained ternary positive electrode material was put into a VC mixing tank and mixed for 2 hours. The material was sieved, demagnetized and packaged to obtain the finished positive electrode material. The relevant physical and chemical performance characterization tests and data analysis were carried out.

[0127] Comparative Example 6

[0128] The difference from Example 1 is that no SrZrO3 doping, WB4 doping / coating, and secondary coating are performed. The preparation method of the positive electrode material includes the following steps:

[0129] (1) Prepare the precursor Ni according to the conventional method 0.65 Co 0.07 Mn 028 (OH)2(D 50 3.4±0.5μm), Li2CO3(D 50 3.5±1μm) and dopant TiNb2O7(D 50 2.0±1.0μm),γ-Al2O3(D 50 1.5±0.5μm) raw materials, weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000g), Li2CO3 (764.10g), TiNb2O7 (8.30g), γ-Al2O3 (7.18g); transfer the materials into a high-speed mixer, adopt a three-stage mode of 200rpm / 2min, 800rpm / 20min, 100rpm / 3min to mix the powders evenly, put them into a crucible and transfer them into an atmosphere muffle furnace, in an oxygen atmosphere, heat to 320℃ at a rate of 2℃ / min and sinter for 3.2h, then heat to 770℃ and sinter for 3.6h, and then heat to 952℃ and sinter for 12.4h; after cooling, crushing and sieving, obtain a positive electrode material doped matrix;

[0130] (2) 1600 g of the obtained doped matrix was sampled and mixed with the coating agent H3BO3 (D 50 2500 mesh) (5.54g), α-Al2O3 (D 50120.0±20.0nm) (3.64g) was put into a high-speed mixer and the powder was mixed evenly in a three-stage mode of 100rpm / 2min, 1200rpm / 30min, and 200rpm / 3min. After being put into a crucible, it was transferred into an atmosphere muffle furnace and heated to 680℃ under an oxygen atmosphere for 8.6h. After cooling, it was crushed and sieved to remove magnetism to obtain a positive electrode material coated matrix;

[0131] (3) 1500 g of the obtained coated matrix sample was put into a high-speed mixer, and the powder was evenly mixed in a three-stage mode of 100 rpm / 2 min, 1000 rpm / 30 min, and 200 rpm / 3 min. After being loaded into a crucible, it was transferred to an atmosphere muffle furnace and sintered at 340 ° C for 6.4 h in a dry air atmosphere. After cooling, it was crushed and sieved to remove magnetism; the obtained ternary positive electrode material was put into a VC mixing tank and mixed for 2 h. The material was sieved, demagnetized, and packaged to obtain the finished positive electrode material, and relevant physical and chemical performance characterization tests and data analysis were carried out.

[0132] Comparative Example 7

[0133] The difference from Example 1 is that no TiNb2O7 and WB4 doping is performed. The preparation method of the positive electrode material includes the following steps:

[0134] (1) Prepare the precursor Ni according to the conventional method 0.65 Co 0.07 Mn 028 (OH)2(D 50 3.4±0.5μm), Li2CO3(D 50 3.5±1μm) and dopant SrZrO3(D 50 2.0±1.0μm),γ-Al2O3(D 50 1.5±0.5μm) raw materials, weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000g), Li2CO3 (764.10g), SrZrO3 (7.87g), γ-Al2O3 (7.18g); transfer the materials into a high-speed mixer, adopt a three-stage mode of 200rpm / 2min, 800rpm / 20min, 100rpm / 3min to mix the powders evenly, put them into a crucible and transfer them into an atmosphere muffle furnace, in an oxygen atmosphere, heat to 320℃ at a rate of 2℃ / min and sinter for 3.2h, then heat to 770℃ and sinter for 3.6h, and then heat to 952℃ and sinter for 12.4h; after cooling, crushing and sieving, obtain a positive electrode material doped matrix;

[0135] (2) 1600 g of the obtained doped matrix was sampled and coated with WB4 (D 50140.0±20.0nm)(4.81g), H3BO3(D 50 2500 mesh) (5.54g), α-Al2O3 (D 50 120.0±20.0nm) (3.64g) was put into a high-speed mixer and the powder was mixed evenly in a three-stage mode of 100rpm / 2min, 1200rpm / 30min, and 200rpm / 3min. After being put into a crucible, it was transferred into an atmosphere muffle furnace and heated to 680℃ under an oxygen atmosphere for 8.6h. After cooling, it was crushed and sieved to remove magnetism to obtain a positive electrode material coated matrix;

[0136] (3) Take 1500g of the obtained coated substrate and mix it with the coating agent Ta2O5(D 50 200.0±20.0nm)(2.15g), C2H3O2Li(D 50 The obtained ternary positive electrode material was put into a VC mixing tank and mixed for 2 hours. The material was sieved, demagnetized and packaged to obtain the finished positive electrode material. The relevant physical and chemical performance characterization tests and data analysis were carried out.

[0137] Comparative Example 8

[0138] The difference from Example 1 is that TiNb2O7 doping and WB4 doping / coating are not performed. The preparation method of the positive electrode material includes the following steps:

[0139] (1) Prepare the precursor Ni according to the conventional method 0.65 Co 0.07 Mn 028 (OH)2(D 50 3.4±0.5μm), Li2CO3(D 50 3.5±1μm) and dopant SrZrO3(D 50 2.0±1.0μm),γ-Al2O3(D 50 1.5±0.5μm) raw materials, weigh Ni 0.65 Co 0.07 Mn 028(OH)2 (2000g), Li2CO3 (764.10g), SrZrO3 (7.87g), γ-Al2O3 (7.18g); transfer the materials into a high-speed mixer, adopt a three-stage mode of 200rpm / 2min, 800rpm / 20min, 100rpm / 3min to mix the powders evenly, put them into a crucible and transfer them into an atmosphere muffle furnace, in an oxygen atmosphere, heat to 320℃ at a rate of 2℃ / min and sinter for 3.2h, then heat to 770℃ and sinter for 3.6h, and then heat to 952℃ and sinter for 12.4h; after cooling, crushing and sieving, obtain a positive electrode material doped matrix;

[0140] (2) 1600 g of the obtained doped matrix was sampled and mixed with the coating agent H3BO3 (D 50 2500 mesh) (5.54g), α-Al2O3 (D 50 120.0±20.0nm) (3.64g) was put into a high-speed mixer and the powder was mixed evenly in a three-stage mode of 100rpm / 2min, 1200rpm / 30min, and 200rpm / 3min. After being put into a crucible, it was transferred into an atmosphere muffle furnace and heated to 680℃ under an oxygen atmosphere for 8.6h. After cooling, it was crushed and sieved to remove magnetism to obtain a positive electrode material coated matrix;

[0141] (3) Take 1500g of the obtained coated substrate and mix it with the coating agent Ta2O5(D 50 200.0±20.0nm)(2.15g), C2H3O2Li(D 50 The obtained ternary positive electrode material was put into a VC mixing tank and mixed for 2 hours. The material was sieved, demagnetized and packaged to obtain the finished positive electrode material. The relevant physical and chemical performance characterization tests and data analysis were carried out.

[0142] Comparative Example 9

[0143] The difference from Example 1 is that SrZrO3 / TiNb2O7 / WB4 doping is not performed. The preparation method of the positive electrode material includes the following steps:

[0144] (1) Prepare the precursor Ni according to the conventional method 0.65 Co 0.07 Mn 028 (OH)2(D 50 3.4±0.5μm), Li2CO3(D 503.5±1μm) and dopant γ-Al2O3 (D 50 1.5±0.5μm) raw materials, weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000g), Li2CO3 (764.10g), γ-Al2O3 (7.18g); transfer the materials into a high-speed mixer, use a three-stage mode of 200rpm / 2min, 800rpm / 20min, 100rpm / 3min to mix the powders evenly, put them into a crucible and transfer them into an atmosphere muffle furnace, in an oxygen atmosphere, heat to 320℃ at a rate of 2℃ / min and sinter for 3.2h, then heat to 770℃ and sinter for 3.6h, and then heat to 952℃ and sinter for 12.4h; after cooling, crushing and sieving, obtain a positive electrode material doped matrix;

[0145] (2) 1600 g of the obtained doped matrix was sampled and coated with WB4 (D 50 140.0±20.0nm)(4.81g), H3BO3(D 50 2500 mesh) (5.54g), α-Al2O3 (D 50 120.0±20.0nm) (3.64g) was put into a high-speed mixer and the powder was mixed evenly in a three-stage mode of 100rpm / 2min, 1200rpm / 30min, and 200rpm / 3min. After being put into a crucible, it was transferred into an atmosphere muffle furnace and heated to 680℃ under an oxygen atmosphere for 8.6h. After cooling, it was crushed and sieved to remove magnetism to obtain a positive electrode material coated matrix;

[0146] (3) Take 1500g of the obtained coated substrate and mix it with the coating agent Ta2O5(D 50 200.0±20.0nm)(2.15g), C2H3O2Li(D 50 The obtained ternary positive electrode material was put into a VC mixing tank and mixed for 2 hours. The material was sieved, demagnetized and packaged to obtain the finished positive electrode material. The relevant physical and chemical performance characterization tests and data analysis were carried out.

[0147] Comparative Example 10

[0148] The difference from Example 1 is that SrZrO3 / TiNb2O7 / WB4 doping and WB4 coating are not performed. The preparation method of the positive electrode material includes the following steps:

[0149] (1) According to the conventional method, the precursor Ni 0.65 Co 0.07 Mn 028 (OH)2(D 50 3.4±0.5 μm), Li2CO3(D 50 3.5±1 μm) and the dopant γ-Al2O3(D 50 1.5±0.5 μm) were prepared, and Ni 0.65 Co 0.07 Mn 028 (OH)2(2000 g), Li2CO3(764.10 g), γ-Al2O3(7.18 g) were weighed; the materials were transferred into a high-speed mixer, and the powders were mixed uniformly by using a three-stage mode of 200 rpm / 2 min, 800 rpm / 20 min and 100 rpm / 3 min, and then were loaded into a crucible and transferred into a muffle furnace in an oxygen atmosphere, and were sintered at a rate of 2 ℃ / min to 320 ℃ for 3.2 h, then were sintered at 770 ℃ for 3.6 h, and then were sintered at 952 ℃ for 12.4 h; after cooling, the positive electrode material doped matrix was obtained after crushing and sieving;

[0150] (2) The obtained doped matrix was sampled at 1600 g, and the coating agent H3BO3(D 50 2500 mesh) (5.54 g) and α-Al2O3(D 50 120.0±20.0 nm) (3.64 g) were put into a high-speed mixer, and the powders were mixed uniformly by using a three-stage mode of 100 rpm / 2 min, 1200 rpm / 30 min and 200 rpm / 3 min, and then were loaded into a crucible and transferred into a muffle furnace in an oxygen atmosphere, and were sintered at 680 ℃ for 8.6 h; after cooling, the positive electrode material coated matrix was obtained after crushing and sieving and removing magnetism;

[0151] (3) The obtained coated matrix was sampled at 1500 g, and the coating agent Ta2O5(D 50 200.0±20.0 nm) (2.15 g) and C2H3O2Li(D 50 80.0±10.0 nm) (7.64 g) were put into a high-speed mixer, and the powders were mixed uniformly by using a three-stage mode of 100 rpm / 2 min, 1000 rpm / 30 min and 200 rpm / 3 min, and then were loaded into a crucible and transferred into a muffle furnace in a dry air atmosphere, and were sintered at 340 ℃ for 6.4 h; after cooling, the positive electrode material was obtained after crushing, sieving and removing magnetism; the obtained ternary positive electrode material was put into a VC mixing tank and mixed for 2 h, and then was sieved, removed of magnetism, packaged to obtain the finished positive electrode material, and related physical and chemical performance characterization tests and data analysis were carried out.

[0152] Comparative Example 11

[0153] The difference from Example 1 is that only γ-Al2O3 doping and α-Al2O3 coating are performed. The preparation method of the positive electrode material includes the following steps:

[0154] (1) Prepare the precursor Ni according to the conventional method 0.65 Co 0.07 Mn 028 (OH)2(D 50 3.4±0.5μm), Li2CO3(D 50 3.5±1μm) and dopant γ-Al2O3 (D 50 1.5±0.5μm) raw materials, weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000g), Li2CO3 (764.10g), γ-Al2O3 (7.18g); transfer the materials into a high-speed mixer, use a three-stage mode of 200rpm / 2min, 800rpm / 20min, 100rpm / 3min to mix the powders evenly, put them into a crucible and transfer them into an atmosphere muffle furnace, in an oxygen atmosphere, heat to 320℃ at a rate of 2℃ / min and sinter for 3.2h, then heat to 770℃ and sinter for 3.6h, and then heat to 952℃ and sinter for 12.4h; after cooling, crushing and sieving, obtain a positive electrode material doped matrix;

[0155] (2) 1600 g of the obtained doped matrix was sampled and mixed with the coating agent α-Al2O3 (D 50 120.0±20.0nm) (3.64g) was put into a high-speed mixer and the powder was mixed evenly in a three-stage mode of 100rpm / 2min, 1200rpm / 30min, and 200rpm / 3min. After being put into a crucible, it was transferred into an atmosphere muffle furnace and heated to 680℃ under an oxygen atmosphere for 8.6h. After cooling, it was crushed and sieved to remove magnetism to obtain a positive electrode material coated matrix;

[0156] (3) 1500 g of the obtained coated matrix sample was put into a high-speed mixer, and the powder was evenly mixed in a three-stage mode of 100 rpm / 2 min, 1000 rpm / 30 min, and 200 rpm / 3 min. After being loaded into a crucible, it was transferred to an atmosphere muffle furnace and sintered at 340 ° C for 6.4 h in a dry air atmosphere. After cooling, it was crushed and sieved to remove magnetism; the obtained ternary positive electrode material was put into a VC mixing tank and mixed for 2 h. The material was sieved, demagnetized, and packaged to obtain the finished positive electrode material, and relevant physical and chemical performance characterization tests and data analysis were carried out.

[0157] Comparative Example 12

[0158] The difference from Example 1 is that only one coating modification is performed. The preparation method of the positive electrode material includes the following steps:

[0159] (1) Prepare the precursor Ni according to the conventional method 0.65 Co 0.07 Mn 028 (OH)2(D 50 3.4±0.5μm), Li2CO3(D 50 3.5±1μm) raw materials, weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000g), Li2CO3 (764.10g); the materials were transferred to a high-speed mixer and the powders were evenly mixed using a three-stage mode of 200 rpm / 2min, 800 rpm / 20min, and 100 rpm / 3min. After being loaded into a crucible, the mixture was transferred to an atmosphere muffle furnace and sintered at a rate of 2°C / min to 320°C in an oxygen atmosphere for 3.2h, then to 770°C for 3.6h, and then to 952°C for 12.4h. After cooling, crushing and sieving, a sintered matrix of the positive electrode material was obtained;

[0160] (2) 1600 g of the obtained doped matrix was sampled and coated with WB4 (D 50 140.0±20.0nm)(4.81g), H3BO3(D 50 2500 mesh) (5.54g), α-Al2O3 (D 50 120.0±20.0nm) (3.64g) was put into a high-speed mixer, and the three powders were mixed evenly at 100rpm / 2min, 1200rpm / 30min, and 200rpm / 3min in a three-stage mode. The three powders were then put into a crucible, heated to 680℃ in an oxygen atmosphere, and sintered for 8.6h. After cooling, the powders were crushed and sieved to remove magnetism, thereby obtaining a positive electrode material coated matrix.

[0161] (3) 1500 g of the obtained coated matrix sample was put into a high-speed mixer, and the powder was evenly mixed in a three-stage mode of 100 rpm / 2 min, 1000 rpm / 30 min, and 200 rpm / 3 min, and then put into a crucible, sintered at 340 ° C for 6.4 h in a dry air atmosphere, and crushed and sieved after cooling to remove magnetism; the obtained ternary positive electrode material was put into a VC mixing tank and mixed for 2 h, the material was sieved, demagnetized, and packaged to obtain the finished ternary positive electrode material, and relevant physical and chemical performance characterization tests and data analysis were carried out.

[0162] Comparative Example 13

[0163] The difference from Example 1 is that only secondary coating modification is performed. The preparation method of the positive electrode material includes the following steps:

[0164] (1) Prepare the precursor Ni according to the conventional method 0.65 Co 0.07 Mn 028 (OH)2(D 50 3.4±0.5μm), Li2CO3(D 50 3.5±1μm) raw materials, weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000g), Li2CO3 (764.10g); the materials were transferred to a high-speed mixer and mixed evenly using a three-stage mode of 200 rpm / 2min, 800 rpm / 20min, and 100 rpm / 3min. After being loaded into a crucible, the mixture was transferred to an atmosphere muffle furnace and sintered at a rate of 2°C / min to 320°C in an oxygen atmosphere for 3.2h, then heated to 770°C for 3.6h, and then heated to 952°C for 12.4h. After cooling, crushing and sieving, a sintered matrix of the positive electrode material was obtained;

[0165] (2) 1600 g of the obtained doped matrix sample was put into a high-speed mixer and mixed evenly according to the three-stage mode of 100 rpm / 2 min, 1200 rpm / 30 min, and 200 rpm / 3 min. The mixture was then placed in a crucible and heated to 680 ° C in an oxygen atmosphere for 8.6 h. After cooling, the mixture was crushed and sieved to remove magnetism to obtain the second sintered positive electrode material matrix;

[0166] (3) 1500 g of the obtained calcined matrix was sampled and coated with Ta2O5 (D 50 200.0±20.0nm)(2.15g), C2H3O2Li(D 50 The obtained ternary positive electrode material was put into a VC mixing tank and mixed for 2 hours. The material was sieved, demagnetized and packaged to obtain the finished ternary positive electrode material. The relevant physical and chemical performance characterization tests and data analysis were carried out.

[0167] Comparative Example 14

[0168] The difference from Example 1 is that no doping and primary / secondary coating modification are performed. The preparation method of the positive electrode material includes the following steps:

[0169] (1) Prepare the precursor Ni according to the conventional method 0.65 Co 0.07Mn 028 (OH)2(D 50 3.4±0.5μm), Li2CO3(D 50 3.5±1μm) raw materials, weigh Ni 0.65 Co 0.07 Mn 028 (OH)2 (2000g), Li2CO3 (764.10g); the materials were transferred to a high-speed mixer and mixed evenly using a three-stage mode of 200 rpm / 2min, 800 rpm / 20min, and 100 rpm / 3min. After being loaded into a crucible, the mixture was transferred to an atmosphere muffle furnace and sintered at a rate of 2°C / min to 320°C in an oxygen atmosphere for 3.2h, then to 770°C for 3.6h, and then to 952°C for 12.4h. After cooling, crushing and sieving, a sintered matrix of the positive electrode material was obtained;

[0170] (2) 1600 g of the obtained doped matrix sample was put into a high-speed mixer and mixed evenly according to the three-stage mode of 100 rpm / 2 min, 1200 rpm / 30 min, and 200 rpm / 3 min. The mixture was then placed in a crucible and heated to 680 ° C in an oxygen atmosphere for 8.6 h. After cooling, the mixture was crushed and sieved to remove magnetism to obtain the second sintered positive electrode material matrix;

[0171] (3) 1500 g of the obtained dialkyl matrix was sampled and put into a high-speed mixer, and mixed evenly according to the three-stage mode of 100 rpm / 2 min, 1000 rpm / 30 min, and 200 rpm / 3 min. The mixture was put into a crucible and sintered at 340 ° C for 6.4 h in a dry air atmosphere. After cooling, it was crushed and sieved to remove magnetism; the obtained ternary positive electrode material was put into a VC mixing tank and mixed for 2 h. The material was sieved, demagnetized, and packaged to obtain the finished ternary positive electrode material, and relevant physical and chemical performance characterization tests and data analysis were carried out.

[0172] Experimental example

[0173] 1. Physical and chemical indicators

[0174] The positive electrode materials prepared in the above Examples 1-2 and Comparative Examples 1-14 were respectively tested for element and impurity content, and the physical and chemical indicators of the samples were analyzed using relevant equipment such as a scanning electron microscope, a laser particle size analyzer, and a Swiss Metrohm automatic titrator familiar to technicians. The test results are shown in Table 1 below.

[0175] The SEM images of the ternary cathode materials prepared in Examples 1-2 are shown in FIG. Figure 3 The XRD characterization of the ternary cathode material prepared in Example 1 is further performed, and the characterization results are shown in FIG. Figure 4 .

[0176] Table 1 Physical and chemical index results of ternary positive electrode materials of Examples 1-2 and Comparative Examples 1-14

[0177]

[0178] It can be seen that the basic physical and chemical index test data of Ni6507 and Ni7205 in Examples 1-2 and Comparative Examples 1-14 show that the performance indicators related to tap density, pH, and residual alkali are improved, the tap density is increased, the pH and residual alkali content are reduced, and the materials have better comprehensive performance advantages.

[0179] 2. Electrical performance and cycle performance test

[0180] The positive electrode materials prepared in Examples 1-2 and Comparative Examples 1-14 were prepared into lithium-ion batteries (active material: PVDF:CNT:SP = 97.2:1.1:0.8:0.9, solid content 73.5%) using methods familiar to those skilled in the art, and the obtained positive electrode materials were assembled into button batteries.

[0181] Using the blue electric test system, the first charge and discharge specific capacity (see Example 1-2) was measured in the voltage range of 3.0-4.60V at 25°C and 0.1C. Figure 4 (a)-(b)) and 0.2C / 0.5C / 1.0C / 2.0C rate charge / discharge performance (see Example 1-2 Figure 6 (a)-(b) in the figure), and the results are shown in Table 2 below.

[0182] Table 2 Rate discharge / cycle performance test results

[0183]

[0184] It can be seen that by comparing the buckle test data of Ni6507 and Ni7205 in Examples 1-2 with those of the ternary positive electrode single crystal materials in Comparative Examples 1-14, it is reflected that the higher gram-to-gram capacity and rate discharge performance are reflected, and the buckle cycle performance has obvious advantages; and under 1C charge and discharge conditions, Example 1 and Comparative Example 1 are prepared into PIE-116103322-61Ah soft-pack batteries (containing natural graphite for the negative electrode, 9+2+2 wet-process ceramic diaphragm, and HDGT electrolyte with its own formula) according to the battery production process for full battery production and cycle performance testing. Example 1 has a room temperature cycle of 2000 weeks ≥88%, a high temperature cycle of 1380 weeks ≥84%, and Comparative Example 1 has a room temperature cycle of 1300 weeks ≥80%, and a high temperature cycle of 650 weeks ≥82%; it can be seen that the cycle performance of the scheme described in the present invention is significantly improved year-on-year, and the test results are shown in FIG. Figure 7 shown.

[0185] It can be seen that the gram-to-gram capacity of the ternary positive electrode material prepared by the present invention has increased year-on-year, and the rate discharge performance and cycle performance have been improved, and it has excellent all-electric application performance.

[0186] The above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced with equivalents, without departing from the spirit and substance of the claims of the present invention; and such modifications or replacements remain within the scope of the claims of the present invention.

Claims

1. A low-cobalt high-voltage ternary cathode material, characterized in that: It comprises an inner core, and a first coating layer and a second coating layer sequentially coating the inner core surface outwardly; The core formula is Li a (Ni x Co y Mn 1-x-y )(Sr c Al d Zr e Ti f Nb g W h B j )O2; where, 0.5≤x<1.0, 0<y≤0.10, 0.96≤a<1.14, 0<c≤0.008, 0<d≤0.008, 0<e≤0.008, 0<f≤0.0065, 0<g≤0.0065, 0<h≤0.004, 0<j≤0.008; The first coating layer has the general formula W x1 B y1 Al z1 O c1 , where x1=0.5~2.0, y1=1.0~5.0, z1=1.0~2.0, c1=1.0~3.0; The second coating layer has the general formula of Li a1 Ta x2 O3, where a1=0.5~4, x2=1.0~3.

0.

2. A low-cobalt high-voltage ternary cathode material according to claim 1, characterized in that: The preparation method is as follows: a ternary positive electrode material precursor is co-doped and modified with a compound dopant containing Sr / Zr / Al / Nb / Ti / W / B elements and subjected to a first sintering, and the positive electrode material core is obtained after crushing, screening and demagnetization; the positive electrode material core is then mixed with a first coating agent containing a compound of W / Al / B elements and subjected to a second sintering, and the positive electrode material after crushing, screening and demagnetization is obtained; finally, the positive electrode material after the first coating is mixed with a second coating agent containing a compound of Ta / Li elements and subjected to a third sintering, and the positive electrode material after crushing, screening and demagnetization is obtained.

3. A method for preparing the low-cobalt high-voltage ternary cathode material according to claim 1 or 2, characterized in that: The steps include: (1) Ni x Co y Mn 1-x-y (OH)2, lithium source, and compound dopant containing Sr / Zr / Al / Nb / Ti / W / B elements are mixed and sintered for the first time. The precursor of the ternary positive electrode material has 0.5≤x<1.0, 0<y≤0.1, and then is crushed, sieved, and demagnetized to obtain the positive electrode material core Li a (Ni x Co y Mn 1-x-y )(Sr c Al d Zr e Ti f Nb g W h B j )O2; (2) The positive electrode material core is mixed with a first coating agent of a compound containing W / Al / B elements and then sintered for a second time, and then crushed, sieved, and demagnetized to obtain a positive electrode material after the first coating; (3) The positive electrode material after the first coating is mixed with the second coating agent containing the Ta / Li element compound and sintered for the third time, and then crushed, screened, demagnetized, and batch mixed to obtain the finished positive electrode material after the second coating.

4. The method for preparing a low-cobalt high-voltage ternary cathode material according to claim 3, further characterized in that, in step (1), The lithium source is one or more selected from LiOH, LiOH·H2O, Li2CO3, LiNO3 or C2H3O2Li; The doping element compound containing Sr / Zr / Al / Nb / Ti / W / B is selected from SrCO3, SrTiO3, SrO, ZrO2, Zr 0.92 O2Y 0.08 , one or more of ZrB2, SrZrO3, TiNb2O7, NbO2, TiO2, WO3, WB, W2B, WB4, W2B5, H2WPO4, Al2O3, AlF3, Al(OH)3, AlCl3, AlBr3, LiAlH4, Al(BH4)3, AlB2, AlPO4, Al(H2PO4)3, B2O3, H3BO3, NaAlO2, NaAlCl4, Na3AlF6, and LiNbO3; The W / Al / B-containing coating element compound and the Ta / Li-containing coating element compound are one or more selected from Al2O3, AlB2, AlF3, Al(OH)3, WB, W2B, WB4, WO3, H2WPO4, Ta2O5, Ta(OH)5, TaF5, TaCl5, TaBr5, Tal5, B2O3, H3BO3, C2H3O2Li, Li3BO3, Li2WO4, LiAlO2, Li2TiO3, LiTaO3, and Li3PO4.

5. The method for preparing a low-cobalt, high-voltage ternary positive electrode material according to claim 3 or 4, further characterized in that, in step (1), the ratio of the total molar amount of Ni, Co, and Mn in the ternary positive electrode material precursor, the molar amount of Li in the lithium source, and the total molar amount of Sr, Nb, Al, Zr, Ti, W, and B in the dopant is 1:(0.96~1.14):(0.0004~0.026); in step (2), the ratio of the total molar amount of Ni, Co, and Mn in the positive electrode material core to the total molar amount of W, Al, and B in the first coating agent is 1:(0.0004~0.012); in step (3), 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 Ta and Li in the second coating agent is 1:(0.0001~0.0100).

6. The method for preparing a low-cobalt, high-voltage ternary positive electrode material according to claim 3 or 4, further characterized in that the dopant containing Sr / Nb / Al / Zr / Ti / W / B elements is a mixture of γ-Al2O3, SrZrO3, TiNb2O7 and WB4; the first coating agent containing W / Al / B elements is a mixture of WB4, α-Al2O3 and H3BO3; the second coating agent containing Ta / Li includes a mixture of Ta2O5 and anhydrous C2H3O2Li, or a mixture of Ta(OH)5 and anhydrous LiOH.

7. The method for preparing a low-cobalt high-voltage ternary cathode material according to claim 6, further characterized in that: In step (1), Ternary cathode material precursor Ni x Co y Mn 1-x-y The mass ratio of (OH)2 to γ-Al2O3 is 100: (0.02~0.80); Ternary cathode material precursor Ni x Co y Mn 1-x-y The mass ratio of (OH)2 to SrZrO3 is 100: (0.03~0.90); Ternary cathode material precursor Ni x Co y Mn 1-x-y The mass ratio of (OH)2 to TiNb2O7 is 100: (0.015~0.82); Ternary cathode material precursor Ni x Co y Mn 1-x-y The mass ratio of (OH)2 to WB4 is 100: (0.01~0.70); In step (1), the first sintering includes: heating to 700-1100° C. and keeping the temperature for 8-24 hours in an oxygen-containing atmosphere.

8. The method for preparing a low-cobalt high-voltage ternary cathode material according to claim 7, further characterized in that: In step (2), the mass ratio of the cathode material core to WB4 is 100:(0.02~0.80); The mass ratio of the cathode material core to α-Al2O3 is 100: (0.01~0.60); The mass ratio of the cathode material core to H3BO3 is 100: (0.02~0.90); In step (2), the second sintering includes: In an oxygen-containing atmosphere, heat to 380~740℃ and keep warm for 3~16h.

9. The method for preparing a low-cobalt, high-voltage ternary cathode material according to claim 8, further characterized in that: In step (3), the mass ratio of the positive electrode material after the first coating to Ta2O5 is 100: (0.01~0.30); The mass ratio of the positive electrode material after the first coating to anhydrous C2H3O2Li is 100: (0.04~1.50); Alternatively, the mass ratio of the positive electrode material after the first coating to Ta(OH)5 is 100:(0.02-0.50); The mass ratio of the positive electrode material to anhydrous LiOH after the first coating is 100: (0.02~0.70); In step (3), the third sintering includes: heating to 220-480°C and keeping the temperature for 2-12 hours in an atmosphere containing dry air or oxygen-air combination.

10. Use of the low-cobalt, high-voltage ternary positive electrode material according to claim 1 or 2, or the low-cobalt, high-voltage ternary positive electrode material prepared by the preparation method according to any one of claims 3 to 9, in preparing a secondary battery positive electrode sheet or a secondary battery.

11. Use of the low-cobalt high-voltage ternary cathode material according to claim 10 in preparing a secondary battery cathode sheet or a secondary battery, characterized in that: The secondary battery is a lithium-ion battery.

Images