A high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material and its preparation method and lithium-ion battery

Abstract

The present invention discloses a high-voltage, medium-low nickel single-crystal nickel-cobalt-manganese ternary positive electrode material, a preparation method thereof, and a lithium-ion battery. The chemical formula of the high-voltage, medium-low nickel single-crystal nickel-cobalt-manganese ternary positive electrode material is LiNixCoyMn1-x-yMbO2, wherein 0.5≤x≤0.8, 0.05≤y≤0.2, and 0.0005<b≤0.01, and M is selected from one or more of Zr, Al, Ce, Sr, Mg, Ti, Si, La, Ba, Ta, W, Co, Nb, Cr, Mo, Ca, Y, In, Sn, F, and P. The D003 crystal plane lattice stress of the high-voltage, medium-low nickel single-crystal nickel-cobalt-manganese ternary positive electrode material is 0.02-0.07, and the D104 crystal plane lattice stress is 0.05-0.1. A lithium-ion battery assembled with the ternary positive electrode material prepared by the present invention has high specific capacity, high rate performance, and good high-temperature cycle performance and low-temperature discharge performance.

Description

Technical Field

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

[0002] With the rapid development of the new energy industry and increasing consumer demand for lithium-ion battery battery life, developing lithium-ion battery cathode materials with lower costs, higher energy density, and longer cycle life has become a long-term goal in the lithium-ion battery industry. Currently, there are two main approaches to increasing the energy density of ternary materials: increasing the specific capacity of the material, even by increasing the nickel content toward higher nickel content; and increasing the voltage of the material, toward single-crystal ternary materials. Traditional secondary particles contain numerous grain boundaries. These fragile grain boundaries, due to anisotropic expansion and contraction during charge and discharge, can cause severe cracking and pulverization, accelerating the degradation of polycrystalline cathode materials. Single-crystal materials, lacking the degradation caused by internal grain boundaries, generally exhibit more stable structure and performance. Although their specific capacity is lower than that of polycrystalline materials with the same nickel, cobalt, and manganese ratios within the same voltage range, single-crystal materials have a higher overall volumetric energy density due to their higher compaction density and ability to operate at higher voltages.

[0003] Although single-crystal materials do not experience cracking or pulverization due to grain boundaries, the large particle size of single-crystal cathode materials can lead to interlayer slip and intragranular cracking, reducing cycle life. Interlayer slip and intragranular cracking are primarily caused by the higher temperature sintering required to crystallize the cathode material, which causes the original primary particles to gradually grow and fuse. However, this crystallization process is typically very slow and the growth rate is uneven, leading to stress concentration within the single crystal. Furthermore, during cycling, stress is generated along the (003) crystal orientation when lithium ions intercalate and deintercalate within the lattice. Especially at high voltages, increasing the charge and discharge voltage forces more lithium ions to intercalate and deintercalate. The large particle size of single-crystal cathodes makes the internal lithium ion concentration more spatially uneven, resulting in the presence of phases with different unit cell sizes within a single cathode particle. The coexistence of these phases causes lattice strain, which triggers slip in the layer planes, nucleating cracks within the single crystal, forming stacking faults and intragranular cracks. This further accelerates oxygen loss and phase transformation, making the cumulative volume expansion of the ternary material irreversible.

[0004] During the preparation of single-crystal ternary lithium batteries, the single-crystal ternary material exhibits a characteristic (003) crystal orientation after the electrode sheet is pressed. This orientation can cause the material to expand or even rebound in the thickness direction, affecting battery performance and causing uneven electrolyte distribution during charge and discharge, leading to lithium deposition and performance degradation. Therefore, the preparation of high-voltage, medium-low nickel single-crystal ternary cathode materials remains a difficult problem that researchers need to overcome. Summary of the Invention

[0005] In response to the deficiencies and defects mentioned in the above background technology, the present invention provides a high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material and a preparation method thereof and a lithium-ion battery.

[0006] In order to achieve the above object of the invention, the scheme of the present invention is as follows:

[0007] In a first aspect, the present invention proposes a high-voltage, medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material. The chemical formula of the high-voltage, medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material is LiNixCoyMn1-x-yMbO2, wherein 0.5≤x≤0.8, 0.05≤y≤0.2, 0.0005<b≤0.01, and the M is selected from one or more of Zr, Al, Ce, Sr, Mg, Ti, Si, La, Ba, Ta, W, Co, Nb, Cr, Mo, Ca, Y, In, Sn, F, and P. The D003 crystal plane lattice stress of the high-voltage, medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material is 0.02~0.07, and the D104 crystal plane lattice stress is 0.05~0.1.

[0008] Preferably, the D003 and D104 crystal plane lattice stresses of the high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material are obtained by XRD ray diffraction testing and refinement, wherein the scanning range of the XRD test is 15°≤2θ≤80°, the scanning rate is 1.5° / min, and the obtained XRD spectrum is refined using Highscore software and the Rietveld full spectrum fitting refinement method.

[0009] As a preference, the specific surface area of ​​the high voltage medium and low nickel single crystal nickel-cobalt-manganese ternary positive electrode material is 0.3 to 0.6 m 2 / g, compacted density ≥3.45g / cm 3 .

[0010] Preferably, the particle size D50 of the high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material is 3.5-4.5 μm, and the particle size distribution (D90-D10) / D50 is 0.8-1.2.

[0011] Preferably, the high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material contains a coating agent; the coating agent contains one or more of the elements Ti, Mg, W, Al, Ce, Co, F, P and B; the mass of the coating agent accounts for the mass of the ternary active component in a ratio of 0.01wt% to 1wt%.

[0012] A second aspect of the present invention provides a method for preparing a high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material, comprising the following steps:

[0013] (1) uniformly mixing a ternary cathode material precursor, a lithium source, and a compound containing a doping element M according to a stoichiometric ratio;

[0014] (2) The mixed material after step (1) is subjected to a single sintering, wherein the single sintering is a multi-step sintering of a high temperature stage, a low temperature stage, and a sub-high temperature stage; the sintering temperature of the high temperature stage is higher than that of the low temperature stage by ≥400°C; and the sintering temperature of the high temperature stage is higher than that of the sub-high temperature stage by 10 to 50°C.

[0015] (3) crushing the material sintered in step (2), screening it, and performing secondary sintering to obtain the high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material.

[0016] As a preference, the secondary particles of the ternary cathode material precursor in step (1) are loose inside, with a BET range of 15m 2 / g~30m 2 / g, particle size D50 is 3-5μm.

[0017] Preferably, the lithium source in step (1) is one or more of lithium carbonate, lithium nitrate, lithium hydroxide, lithium oxide, lithium acetate, and lithium oxalate.

[0018] Preferably, in the multi-step sintering in step (2), the sintering temperature range of the high-temperature stage is 800°C to 1000°C, the sintering time is 2h to 6h, the sintering temperature range of the low-temperature stage is 300°C to 500°C, the sintering time is 1 to 4h, and the sintering temperature range of the secondary high-temperature stage is 750°C to 950°C, and the sintering time is 6 to 12h.

[0019] Preferably, in step (3), a coating agent is added to the material after the primary sintering, crushing and screening; the coating agent contains one or more of the elements Ti, Mg, W, Al, Ce, Co, F, P and B.

[0020] Preferably, the atmosphere for the primary sintering and the secondary sintering in steps (2) and (3) is air or oxygen atmosphere.

[0021] In another aspect, the present invention provides a battery comprising the high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material as described above.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The lattice stress of the D003 crystal plane of the high-voltage medium-low nickel single crystal ternary positive electrode material of the present invention is 0.02-0.07, the lattice stress of the D104 crystal plane is 0.05-0.1, the single crystal particle size distribution D50 is 3.5-6 μm, and the diameter spacing is 0.8-1.2. The single crystal ternary positive electrode material with lattice stress within this range can effectively inhibit the stacking faults and intracrystalline cracks formed by the slip triggered along the crystal direction (003) of the single crystal positive electrode material, and the structural stability and intracrystalline cracking of the single crystal are greatly improved, which effectively slows down the capacity decay caused by irreversible expansion of the material during long-term circulation, thereby improving the safety of the material.

[0024] (2) During the preparation method of the present invention, the sintering system is optimized, and multi-step sintering of high temperature section-low temperature section-sub-high temperature section is carried out. Sintering in the high temperature section for a short time can greatly promote the growth of single crystals and obtain large-sized single crystal morphology. Natural cooling to the low temperature section and sintering are similar to cooling in the traditional process, which will cause lattice stress inside the single crystal. Finally, long-term sintering in the sub-high temperature section can improve the crystal structure, enhance the crystallinity of the single crystal, and release the lattice stress inside the crystal, especially the lattice stress of the 003 and 004 crystal directions.

[0025] (3) During the preparation method of the present invention, a high BET ternary precursor with loose secondary particles is selected. The high specific surface area of ​​the precursor can increase the contact area with the lithium source and improve the reaction activity. The loose secondary particles of the precursor can make the obtained single crystal have uniform closed pores, reduce the lattice stress and improve the rate performance.

[0026] (4) Due to the characteristic of the single crystal ternary material having a crystal orientation (003) after the electrode is pressed, this orientation will cause the material to expand or even rebound in the thickness direction, making the electrolyte unevenly distributed during the charge and discharge process of the battery, causing lithium precipitation and battery performance degradation. In order to limit the volume expansion or rebound of the single crystal ternary material in the crystal direction (003), in the present invention, by limiting the lattice stress of the 003 crystal direction of the high voltage medium and low nickel single crystal ternary positive electrode material, the irreversible expansion of the ternary single crystal material in the crystal direction 003 can be limited, thereby reducing the expansion of the ternary material and the electrode in the thickness direction and improving the battery performance. The lithium ion battery assembled with the ternary positive electrode material prepared by the present invention has high specific capacity, high rate performance, and good high temperature cycle performance and low temperature discharge performance.

[0027] The positive electrode active material of the present invention has a simple preparation process and is easy to operate, and is suitable for large-scale industrial production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a scanning electron microscope image of the single crystal nickel-cobalt-manganese ternary positive electrode material prepared in Example 1;

[0029] Figure 2 This is a scanning electron microscope image of the single crystal nickel-cobalt-manganese ternary positive electrode material prepared in Example 2;

[0030] Figure 3 This is a scanning electron microscope image of the single crystal nickel-cobalt-manganese ternary positive electrode material prepared in Example 3;

[0031] Figure 4 This is a scanning electron microscope image of the single crystal nickel-cobalt-manganese ternary positive electrode material prepared in Example 4;

[0032] Figure 5 This is a scanning electron microscope image of the single crystal nickel-cobalt-manganese ternary positive electrode material prepared in Comparative Example 1;

[0033] Figure 6 This is a scanning electron microscope image of the single crystal nickel-cobalt-manganese ternary positive electrode material prepared in Comparative Example 2;

[0034] Figure 7 It is the 1C cycle retention rate curve of Examples 1, 2, 3, 4 and Comparative Examples 1 and 2. DETAILED DESCRIPTION

[0035] To facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed form below in conjunction with the accompanying drawings and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0036] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0037] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0038] Test method:

[0039] A C2032 button cell was prepared using a ternary positive electrode material as the active material according to a method comprising the following steps: the active material, the conductive agent Super P, and the binder PVDF were dispersed in N-methylpyrrolidone (NMP) in a mass ratio of 95:2:3 with a solid content of 70%, and ball milled to form a uniform positive electrode slurry; the positive electrode slurry was coated on the rough surface of a clean aluminum foil with a coater, and then placed in a vacuum oven at 120°C for 12 hours to obtain a pole piece with a compaction density of 3.45 g / cm 3; The prepared electrode was used, with the lithium sheet as the counter electrode and Celgard2400 as the diaphragm to assemble a 2032 button battery in an argon glove box; the electrolyte used in assembling the 2032 button battery was a solution with a concentration of LiPF6 of 1 mol / L obtained by dissolving LiPF6 in a mixed solvent of ethyl carbonate (EC) and diethyl carbonate (DMC) (volume ratio EC:DMC=1:1).

[0040] The button battery of this patent is tested on the Xinwei Blue Electric Tester (model: CT-4008Tn-5V20mA-164). Specifically, it includes: 1) First, each prepared C2032 button battery is left to stand at room temperature for one night, and then charged at a constant current rate of 0.1C to the charging cut-off voltage, and then charged at a constant voltage to 0.05mA. After standing for 5 minutes, it is discharged at a constant current rate of 0.1C to the discharge cut-off voltage to obtain a 0.1C first-cycle discharge capacity; 2) Then, it is charged at a constant current and constant voltage rate of 0.33C, and discharged at a constant current rate of 0.2C, 0.5C, and 1C respectively to obtain 0. .2C, 0.5C, and 1C discharge capacities, 1C / 0.2C capacity retention rate = 1C discharge capacity / 0.2C first-cycle discharge capacity * 100%; 3) Finally, constant current and constant voltage charging was performed at 0.33C, and charge and discharge cycle test was performed at a discharge rate of 1C. The capacity retention rate after 50 cycles = 1C discharge capacity after 50 cycles / 1C first-cycle discharge capacity * 100%; All tests were carried out at room temperature, and the voltage range of the charge and discharge tests was between 3 and 4.4V.

[0041] Example 1:

[0042] A high voltage medium and low nickel single crystal nickel cobalt manganese ternary positive electrode material of the present invention, the chemical formula of which is LiNi 0.6 Co 0.1 Mn 0.3 MbO2, median particle size D50 is 3.8μm, D003 crystal plane lattice stress is 0.03, D104 crystal plane lattice stress is 0.06, BET is 0.48m 2 / g. Figure 1 This is a scanning electron microscope image of the high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material of Example 1.

[0043] The lattice stress was obtained by XRD diffraction testing and refinement. The scanning range of the XRD test was 10°≤2θ≤80°, the scanning rate was 1.6° / min, and the obtained XRD spectrum was refined using Highscore software. The XRD test was performed using Malvern Panalytical Aeris.

[0044] The preparation method of the high voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material of this embodiment is as follows:

[0045] (1) According to the molar ratio of transition metal to lithium of 1:1.05, weigh the ternary precursor Ni 0.6 Co 0.1 Mn 0.3 (OH)2, lithium carbonate and additive ZrO2, the weighed materials are added to a small high-speed mixer, first mixed at a speed of 200 rpm for 5 minutes, and then mixed at a speed of 1100 rpm for 20 minutes;

[0046] (2) The mixture of step (1) is sintered in an air atmosphere using a 10m kiln with an air flow rate of 100m 3 / h, the sintering procedure is room temperature → 940℃ / 6h → 400℃ / 3h → 900℃ / 8h, which is specifically divided into a heating section and a holding section: the average heating rate of the entire heating section is about 3℃ / min; the holding section is divided into a high-temperature sintering section, a low-temperature holding section and a sub-high-temperature sintering section, the high-temperature sintering section performs the first stage of high-temperature sintering at 940℃, and the first stage of high-temperature sintering time is 6h; then enters the low-temperature holding section, and the low-temperature section is held at 400℃ for 3h; then the temperature is raised to 900℃ for the second stage of sub-high-temperature sintering, and the second stage of sintering time is 8h; the obtained sintered material is coarsely broken by a roller, then pulverized by a jet mill, and passed through a 300-mesh sieve to remove the sieve material to obtain the electrode base material A;

[0047] (3) The electrode matrix material A obtained in step (2) is mixed with the coating agent Al2O3, added to a small high-speed mixer, first mixed at a speed of 200 rpm for 5 minutes, then mixed at a speed of 800 rpm for 10 minutes, and the mixture is sintered in an air atmosphere using a 10m kiln at a sintering temperature of 450°C and a sintering time of 8 hours. The obtained sintered material is passed through a 300-mesh sieve to remove the oversize material, and a material with a D50 of 3.8 μm is obtained, which is a high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material. Its electron microscope photo is shown as follows: Figure 1 shown.

[0048] Example 2:

[0049] A high voltage medium and low nickel single crystal nickel cobalt manganese ternary positive electrode material of the present invention, the chemical formula of which is LiNi 0.7 Co 0.1 Mn 0.2 MbO2, median particle size D50 is 3.8μm, D003 crystal plane lattice stress is 0.05, D104 crystal plane lattice stress is 0.08, BET is 0.5m 2 / g. Figure 2 This is a scanning electron microscope image of the high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material of Example 2.

[0050] The preparation method of this embodiment is basically the same as that of embodiment 1, except that the ternary precursor in step (1) is Ni 0.7 Co 0.1 Mn 0.2 (OH)2, the lithium source is lithium hydroxide; the sintering temperature of the sub-high temperature section in the insulation stage of step (2) is different. The sintering procedure of step (2) of this embodiment is: room temperature → 940℃ / 6h → 400℃ / 3h → 915℃ / 8h.

[0051] Example 3:

[0052] A high voltage medium and low nickel single crystal nickel cobalt manganese ternary positive electrode material of the present invention, the chemical formula of which is LiNi 0.6 Co 0.1 Mn 0.3 MbO2, median particle size D50 is 4.0 μm, D003 crystal plane lattice stress is 0.07, D104 crystal plane lattice stress is 0.10, BET is 0.46m 2 / g. Figure 3 This is a scanning electron microscope image of the high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material of Example 3.

[0053] The preparation method of this embodiment is basically the same as that of Example 1, with the only difference being the sintering temperature of the sub-high temperature section in the heat preservation stage of step (2). The sintering procedure of step (2) of this embodiment is: room temperature → 940°C / 6h → 400°C / 3h → 930°C / 8h.

[0054] Example 4

[0055] A high voltage medium and low nickel single crystal nickel cobalt manganese ternary positive electrode material of the present invention, the chemical formula of which is LiNi 0.8 Co 0.1 Mn 0.1 MbO2, median particle size D50 is 3.7 μm, D003 crystal plane lattice stress is 0.06, D104 crystal plane lattice stress is 0.9, BET is 0.51m 2 / g. Figure 4 This is a scanning electron microscope image of the high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material of Example 4.

[0056] The preparation method of this embodiment is basically the same as that of Example 1, with the following differences:

[0057] The molar ratio of transition metal to lithium in step (1) is 1:1.03. The ternary precursor Ni 0.8 Co 0.1 Mn 0.1 (OH)2, lithium hydroxide and additive MgO2;

[0058] The sintering procedure of step (2) is: room temperature → 940°C / 6h → 400°C / 3h → 920°C / 8h;

[0059] The coating agent in step (3) is TiO2.

[0060] Comparative Example 1:

[0061] The chemical formula of the ternary cathode material in this comparative example is LiNi 0.6 Co 0.1 Mn 0.3 MbO2, median particle size D50 is 4.0 μm, D003 crystal plane lattice stress is 0.09, D104 crystal plane lattice stress is 0.14, BET is 0.44m 2 / g. Figure 5 This is a scanning electron microscope image of the single crystal nickel-cobalt-manganese ternary positive electrode material of comparative example 1.

[0062] The preparation method of this comparative example is basically the same as that of Example 1, except that the high-temperature sintering method in step (2) is different. Only two stages of high-temperature sintering are performed. The sintering system of this comparative example is: room temperature → 940°C / 6h → 900°C / 8h.

[0063] Comparative Example 2:

[0064] The chemical formula of the ternary cathode material in this comparative example is LiNi 0.6 Co 0.1 Mn 0.3 MbO2, median particle size D50 is 4.3 μm, D003 crystal plane lattice stress is 0.13, D104 crystal plane lattice stress is 0.19, BET is 0.41m 2 / g. Figure 6 This is a scanning electron microscope image of the high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material of comparative example 2.

[0065] The preparation method of this comparative example is basically the same as that of Example 1, except that the high-temperature sintering method in step (2) is different. Two-stage high-temperature sintering is not performed. The sintering system of this comparative example is: room temperature → 940°C / 14h.

[0066] Performance testing:

[0067] Table 1 shows the performance comparison of the button batteries of Examples 1, 2, 3 and Comparative Examples 1 and 2.

[0068] Table 1 Comparison of lithium ion battery performance of Examples 1, 2, 3, 4 and Comparative Examples 1 and 2

[0069] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 (003) crystal plane lattice stress 0.03 0.05 0.07 0.06 0.10 0.13 0.1C discharge capacity (mAh / g) 194.17 193.74 193.52 193.11 190.35 188.23 0.2C discharge capacity (mAh / g) 182.63 180.39 180.14 180.87 178.35 175.87 0.5C / 0.2C(%) 93.6 92.40 91.33 91.87 90.85 89.89 1C / 0.2C(%) 88.27 88.17 88.21 88.41 87.66 86.43 50-week cycle retention rate (%) 90.55 88.72 88.12 87.83 84.17 82.46

[0070] It can be seen from the examples and comparative examples in Table 1 that, compared with the single crystal ternary positive electrode material prepared by the traditional sintering process, the single crystal ternary positive electrode material prepared by the present invention can control the (003) crystal plane lattice stress of the material within the range of 0.02 to 0.07, effectively improving the irreversible expansion and even rebound of the ternary single crystal material in the thickness direction of the electrode sheet, thereby improving the capacity, rate and cycle performance of the battery.

Claims

1. A high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary cathode material, wherein the chemical formula of the high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary cathode material is LiNixCoyMn1-x-yMbO2, wherein: 0.5≤x≤0.8, 0.05≤y≤0.2, 0.0005<b≤0.01, the M is selected from one or more of Zr, Al, Ce, Sr, Mg, Ti, Si, La, Ba, Ta, W, Co, Nb, Cr, Mo, Ca, Y, In, Sn, F, and P, and the D003 crystal plane lattice stress of the high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material is 0.02-0.07, and the D104 crystal plane lattice stress is 0.05-0.

1.

2. The high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material according to claim 1, characterized in that: The specific surface area of ​​the high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material is 0.3 to 0.6 m 2 / g, compacted density ≥3.45g / cm 3 ; and / or, the particle size D50 of the high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material is 3.5-4.5μm, and the particle size distribution (D90-D10) / D50 is 0.8~1.

2.

3. The high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material according to claim 1 or 2, characterized in that: The high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material contains a coating agent; the coating agent contains one or more of the elements Ti, Mg, W, Al, Ce, Co, F, P and B; the mass of the coating agent accounts for 0.01wt% to 1wt% of the mass of the ternary positive electrode material.

4. The method for preparing a high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) uniformly mixing a ternary cathode material precursor, a lithium source, and a compound containing a doping element M according to a stoichiometric ratio; (2) sintering the mixed material after step (1) once, wherein the sintering once is a multi-step sintering of a high temperature stage, a low temperature stage, and a sub-high temperature stage; the sintering temperature of the high temperature stage is higher than that of the low temperature stage by ≥400°C; and the sintering temperature of the high temperature stage is higher than that of the sub-high temperature stage by 10 to 50°C; (3) crushing the material sintered in step (2), screening it, and performing secondary sintering to obtain the high-voltage medium-low nickel single crystal nickel-cobalt-manganese ternary positive electrode material.

5. The preparation method according to claim 4, wherein The secondary particles of the ternary cathode material precursor in step (1) are loose inside, and the BET range is 15m 2 / g~30m 2 / g, particle size D50 is 3-5μm.

6. The preparation method according to claim 4, wherein In the step (1), the lithium source is one or more of lithium carbonate, lithium nitrate, lithium hydroxide, lithium oxide, lithium acetate, and lithium oxalate.

7. The preparation method according to any one of claims 4 to 6, characterized in that In the multi-step sintering described in step (2), the sintering temperature range of the high-temperature stage is 800℃~1000℃, the sintering time is 2h~6h, the sintering temperature range of the low-temperature stage is 300℃~500℃, the sintering time is 1~4h, and the sintering temperature range of the second high-temperature stage is 750℃~950℃, and the sintering time is 6~12h.

8. The preparation method according to any one of claims 4 to 6, characterized in that: In step (3), a coating agent is added to the material after the primary sintering, crushing and screening; the coating agent contains one or more of the elements Ti, Mg, W, Al, Ce, Co, F, P and B.

9. The preparation method according to any one of claims 4 to 6, characterized in that: The atmosphere for the primary sintering and the secondary sintering in steps (2) and (3) is air or oxygen atmosphere.

10. A battery comprising the high-voltage, medium-low-nickel single crystal nickel-cobalt-manganese ternary positive electrode material according to any one of claims 1 to 3 or the high-voltage, medium-low-nickel single crystal nickel-cobalt-manganese ternary positive electrode material prepared by the preparation method according to any one of claims 4 to 9.

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