An ultra-high nickel ternary positive electrode material and its preparation method and application

Abstract

The present invention provides an ultra-high nickel ternary positive electrode material and a preparation method and application thereof. The preparation method comprises the following steps: (1) mixing an ultra-high nickel ternary precursor, a lithium source and an additive, and sintering the mixture to obtain a sintered material; (2) mixing the sintered material and a glycine source, and heat-treating the mixture to obtain the ultra-high nickel ternary positive electrode material; wherein the additive in step (1) comprises any three or a combination of at least four of aluminum oxide, magnesium hydroxide, zirconium oxide, yttrium oxide or tungsten oxide. The present invention improves the structural stability of the ultra-high nickel material and the cycle performance of the material through multi-element doping modification; and at the same time, coating the glycine source to avoid battery flatulence and electrolyte erosion of the interior of the particles, thereby reducing impedance and improving the cycle stability of the material.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries and relates to an ultra-high nickel ternary positive electrode material and a preparation method and application thereof. Background Art

[0002] In recent years, the new energy sector has experienced rapid development. Lithium-ion batteries, as highly efficient energy conversion and storage devices, are widely used in electric vehicles, portable electronic devices, and energy storage power stations. With the explosive growth of electric vehicles in recent years, people have placed higher demands on the range of electric vehicles and the energy density of lithium-ion batteries. As a result, cathode materials for automotive lithium-ion batteries are trending towards high-nickel cathode materials. These high-nickel cathode materials are becoming increasingly popular due to their high energy density and low cost.

[0003] However, as nickel content increases, especially in ultra-high nickel cathode materials (0.95 ≤ nickel content ≤ 1), the extremely high nickel content, while increasing the capacity of the cathode material, also makes the material extremely sensitive to moisture and carbon dioxide. Excessive levels of LiOH and Li2CO3 on the surface of the material lead to poor structural stability, cycling performance, and safety of the cathode material, thereby affecting the overall performance of the battery cell. Excessive residual alkali content can easily cause side reactions with the electrolyte, increasing gas production and reducing the safety performance of the battery cell. At the same time, the generation and expansion of microcracks during the battery cell cycle concentrates all-directional stress at the grain boundaries, leading to intergranular cracking and particle fragmentation, destroying the material's morphology and structure. At the same time, electrolyte infiltration increases side reactions and increases impedance, affecting the transmission of lithium ions and reducing structural stability and cycling performance.

[0004] CN113839015A discloses an ultra-high nickel single-crystal cathode material and its preparation method. The method uses an ultra-high nickel cathode material precursor (nickel-cobalt-manganese-aluminum hydroxide) as the base material. By utilizing high rotational speed and high pressure to fully break up the precursor, and adding a lithium source and strontium carbonate during this process, the lithium source and precursor can be mutually dissolved at a relatively low temperature, leading to crystallization and co-growth, reducing lithium and nickel mixing. Finally, the single-crystal-like material is obtained through calcination.

[0005] CN112310389A discloses a method for preparing an ultra-high nickel single crystal positive electrode material, comprising the following steps: S1. mixing a ternary precursor with lithium hydroxide at a lithium to metal molar ratio of 1.01-1.10:1, adding a dopant, and calcining in an oxygen atmosphere to obtain a primary calcined material; S2. subjecting the primary calcined material to coarse crushing, fine crushing, screening, and demagnetization to obtain a pulverized material; S3. adding the pulverized material and water to a reactor at a water-to-material ratio of 0.5:1-5:1, controlling the temperature of the reactor, and then adding reagents to react, and drying after the reaction is completed to obtain a mixed material; S4. mixing the mixed material with a modified coating agent and placing it in an atmosphere furnace for secondary calcination, and then coarse crushing, fine crushing, screening, and demagnetization to obtain a ternary positive electrode material.

[0006] The ultra-high nickel cathode material described in the above scheme has the problems of poor cycle performance and high surface residual alkali. Therefore, it is very necessary to develop an ultra-high nickel cathode material with both low residual alkali and high cycle stability to improve the electrochemical performance of the material and meet the application of power batteries in electric vehicles. Summary of the Invention

[0007] The purpose of the present invention is to provide an ultra-high nickel ternary positive electrode material and its preparation method and application. The present invention improves the structural stability of the ultra-high nickel material and improves the cycle performance of the material through multi-element doping modification; at the same time, it coats the material with organic acid / organic acid salt, and uses a glycine source to react with the lithium source and other residual alkali on the surface of the ultra-high nickel positive electrode material to remove it, thereby avoiding problems such as irreversible capacity loss and battery flatulence. At the same time, free lithium combines with other coated elements to form a new lithium salt compound coating on the surface of the material, which can effectively prevent the electrolyte from eroding the interior of the particles, reduce impedance, and improve the cycle stability of the material.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for preparing an ultra-high nickel ternary positive electrode material, the preparation method comprising the following steps:

[0010] (1) mixing an ultra-high nickel ternary precursor, a lithium source and an additive, and sintering the mixture to obtain a sintered material;

[0011] (2) mixing a calcined material and a glycine source, and obtaining the ultra-high nickel ternary positive electrode material after heat treatment;

[0012] Wherein, the additive in step (1) includes a combination of any three or at least four of aluminum oxide, magnesium hydroxide, zirconium oxide, yttrium oxide or tungsten oxide.

[0013] The present invention prepares ultra-high nickel ternary positive electrode materials through a solid-phase sintering method, adds additives of at least three metal ions, fully utilizes the various properties of the metal ions in the additives, matches the various metal ions, improves the cycle performance and thermal stability of the material, and comprehensively improves the electrochemical performance of the ultra-high nickel positive electrode material.

[0014] The present invention performs solid-phase mixing of a sintered material and a glycine source and then heat-treats the mixture. The glycine molecule has both acidic and alkaline functional groups, can be ionized in water, and has strong hydrophilicity. However, it is a non-polar amino acid, soluble in polar solvents but difficult to dissolve in non-polar solvents, and has a high boiling point and melting point. The present invention utilizes the acidic functional groups of glycine to react with the lithium source on the surface of the primary sintered product to produce an acid-base neutralization reaction, thereby reducing the residual alkali content on the surface of the positive electrode material. Glycine is directly mixed with the sintered material rather than being used as an additive for water washing or alcohol washing to acid-wash the material. This avoids direct erosion of the surface of the positive electrode material by water washing or alcohol washing, which promotes the dissolution of metals such as lithium and causes capacity loss, and at the same time avoids damage to the surface structure of the material by water washing or alcohol washing. In addition, the addition of glycine salts such as glycinate aluminum and glycinate aluminum zirconium also has a positive effect on coating the surface of the positive electrode material to form a protective coating. The molten organic acid salt can react with the residual alkali (OH) on the surface of the sintered product. - 、CO3 2- ) reacts and removes the free lithium on the surface, combining with other coated elements (such as Al or Zr) to form a lithium salt compound, forming a protective coating on the surface of the positive electrode material, which greatly reduces the residual alkali on the surface of the material. At the same time, it can effectively isolate the electrolyte from corroding the interior of the material, inhibit the occurrence of side reactions, and has the functions of stabilizing the structure, improving thermal stability, reducing impedance, and improving material circulation.

[0015] Preferably, the chemical formula of the ultra-high nickel ternary precursor in step (1) is Ni x Co y Mn z (OH)2. Wherein, x+y+z=1, 0.95≤x<1, for example, 0.95, 0.96, 0.97, 0.98 or 0.99, etc., 0.01≤y≤0.1, for example, 0.01, 0.02, 0.05, 0.08 or 0.1, etc., 0.01≤z≤0.1, for example, 0.01, 0.02, 0.05, 0.08 or 0.1, etc.

[0016] Preferably, the lithium source includes lithium hydroxide and / or lithium carbonate.

[0017] Preferably, the ratio of the molar amount of lithium element in the lithium source to the total molar amount of metal elements in the ultra-high nickel ternary precursor is (1.01-1.1):1, for example: 1.01:1, 1.02:1, 1.05:1, 1.08:1 or 1.1:1, etc.

[0018] Preferably, the additives in step (1) include aluminum oxide, magnesium hydroxide, zirconium oxide, yttrium oxide and tungsten oxide.

[0019] Preferably, the mass ratio of the magnesium hydroxide to the ultra-high nickel ternary precursor is (0.1-0.4):100, for example: 0.1:100, 0.2:100, 0.3:100 or 0.4:100, etc.

[0020] Preferably, the mass ratio of the aluminum oxide to the ultra-high nickel ternary precursor is (0.1-0.4):100, for example: 0.1:100, 0.2:100, 0.3:100 or 0.4:100, etc.

[0021] Preferably, the mass ratio of the yttrium oxide to the ultra-high nickel ternary precursor is (0.05-0.3):100, for example: 0.05:100, 0.08:100, 0.1:100, 0.2:100 or 0.3:100, etc.

[0022] Preferably, the mass ratio of the zirconium oxide to the ultra-high nickel ternary precursor is (0.05-0.3):100, for example: 0.05:100, 0.08:100, 0.1:100, 0.2:100 or 0.3:100, etc.

[0023] Preferably, the mass ratio of the tungsten oxide to the ultra-high nickel ternary precursor is (0.05-0.3):100, for example: 0.05:100, 0.08:100, 0.1:100, 0.2:100 or 0.3:100, etc.

[0024] In the ultra-high nickel ternary positive electrode material of the present invention, Mg 2+ Due to its low valence and similar ionic radius to Li+, it can enter the main material lattice and occupy the Li layer, stabilizing the structure of the material. 3+ It is easier to incorporate lattice-stabilized structure and reduce the degree of cation mixing. Although the addition of Mg and Al reduces the initial capacity of the material, the appropriate amount of Mg and Al doping can significantly improve the cycle performance and thermal stability of the material; the addition of Zr can make up for the problem of reduced initial capacity caused by Mg and Al doping. A small amount of Zr 4+ Entering the crystal lattice can stabilize the lithium ion diffusion channel, enrich more on the surface of the material to form a fast ion conductor, optimize the grain boundary, increase the lithium ion conductivity and improve the DCR of the material; 3+Due to the increase in ion radius, the incorporation into the lattice will cause the increase in the material unit cell parameters and the unit cell volume, thereby increasing the volume of the lithium ion transmission path, further increasing the diffusion rate of lithium ions, inhibiting phase change under high voltage, and improving the thermal stability of the material. At the same time, it can also improve the rate performance of the material and have good electrochemical reversibility; the W element can refine the grains, improve the morphology of the material, and enhance the cycle performance of the material.

[0025] Preferably, the temperature of the sintering treatment in step (1) is 600-900°C, for example, 600°C, 650°C, 700°C, 800°C or 900°C, and preferably 650-750°C.

[0026] Preferably, the sintering treatment time is 8 to 24 hours, for example, 8 hours, 10 hours, 12 hours, 16 hours, 20 hours or 24 hours, etc., preferably 10 to 20 hours.

[0027] Preferably, the glycine source in step (2) comprises glycine and / or glycine salt.

[0028] Preferably, the glycinate comprises any one of aluminum glycinate, magnesium glycinate or aluminum zirconium glycinate, or a combination of at least two thereof.

[0029] Preferably, the mass ratio of the glycine source and the calcined material in step (2) is (0.1-5):100, for example: 0.1:100, 0.5:100, 1:100, 2:100, 3:100, 4:100 or 5:100, etc., preferably (0.1-3):100.

[0030] Preferably, the temperature of the heat treatment in step (2) is 250-600°C, for example, 250°C, 300°C, 350°C, 400°C, 500°C or 600°C, and preferably 300-600°C.

[0031] Preferably, the heat treatment time is 6 to 24 hours, for example, 6 hours, 10 hours, 12 hours, 16 hours, 20 hours or 24 hours, etc., preferably 6 to 15 hours.

[0032] In the second aspect, the present invention provides an ultra-high nickel ternary positive electrode material, which is prepared by the method described in the first aspect. The ultra-high nickel ternary positive electrode material includes a core and a coating layer arranged on the surface of the core. The chemical formula of the core is Li 1+y (Ni a Co b Mn 1-a-b-c B c ) 1-yO2, wherein 0≤y≤0.1, for example: 0, 0.01, 0.02, 0.05, 0.08 or 0.1, etc., 0.95≤a≤1, for example: 0.95, 0.96, 0.97, 0.98 or 0.99, etc., 0.01≤b≤0.1, for example: 0.01, 0.02, 0.05, 0.08 or 0.1, etc., 0<c≤0.05, for example: 0.01, 0.02, 0.03, 0.04 or 0.05, etc., B is Mg 2+ 、Al 3+ 、Zr 4+ 、Y 3+ or W 6+ Any one or a combination of at least two of .

[0033] In a third aspect, the present invention provides a positive electrode plate, which comprises the ultra-high nickel ternary positive electrode material as described in the second aspect.

[0034] In a fourth aspect, the present invention provides a lithium-ion battery, comprising the positive electrode sheet as described in the third aspect.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The present invention prepares ultra-high nickel ternary positive electrode materials by a solid phase sintering method, adds additives of at least three metal ions, makes full use of the various properties of the metal ions in the additives, matches the various metal ions, improves the cycle performance and thermal stability of the material, and comprehensively improves the electrochemical performance of the ultra-high nickel positive electrode material. The acidic functional group of glycine is used to react with the lithium source on the surface of the primary sintered product to produce an acid-base neutralization reaction, thereby reducing the residual alkali content on the surface of the positive electrode material. Glycine is directly mixed with the primary sintered material, avoiding direct corrosion of the surface of the positive electrode material by water washing or alcohol washing, which promotes the dissolution of metals such as lithium and causes loss of capacity, and at the same time avoids damage to the surface structure of the material by water washing or alcohol washing. In addition, the addition of glycine salts such as glycinate aluminum and glycinate aluminum zirconium also has a positive effect on coating the surface of the positive electrode material to form a protective coating. The molten organic acid salt can react with the residual alkali (OH) on the surface of the sintered product. - 、CO3 2- ) reacts and is removed, so that the free lithium on the surface combines with other coated elements (Al or Zr, etc.) to form a lithium salt compound, forming a protective coating on the surface of the positive electrode material, which greatly reduces the residual alkali on the surface of the material. At the same time, it can effectively isolate the electrolyte from the corrosion of the inside of the material, inhibit the occurrence of side reactions, and has a stable structure, improved thermal stability, reduced impedance, and improved material circulation functions.

[0037] (2) The battery made of the positive electrode material of the present invention has a first-week charge capacity of more than 244.3 mAh / g, a first-week discharge capacity of more than 216.3 mAh / g, a first-week coulombic efficiency of more than 88.9%, a capacity retention rate of more than 88.9% after 50 cycles, and a 1C discharge capacity of more than 200.2 mAh / g. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is an SEM image of the ultra-high nickel positive electrode material described in Example 4.

[0039] Figure 2 This is an SEM image of the ultra-high nickel positive electrode material described in Comparative Example 1. DETAILED DESCRIPTION

[0040] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0041] Example 1

[0042] This embodiment provides an ultra-high nickel ternary positive electrode material, and the preparation method of the ultra-high nickel ternary positive electrode material is as follows:

[0043] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 and battery-grade lithium hydroxide monohydrate are mixed in a high-pressure mixer at a lithium to metal molar ratio of 1.01:1, and 0.1wt% of magnesium hydroxide, 0.1wt% of aluminum oxide, and 0.05wt% of zirconium oxide are added to the ternary precursor. The mixture is heated at 700°C in an oxygen atmosphere at a heating rate of 2°C / min for 10 hours, and naturally cooled in the furnace. After that, the mixture is crushed, sieved through 325 mesh, and demagnetized to obtain a primary sintered material for an ultra-high nickel positive electrode material.

[0044] (2) The primary sintered material was mixed evenly with glycine and aluminum glycinate in an amount of 0.3 wt% of the primary sintered material, and then heated at 450 ° C for 6 h at a heating rate of 2 ° C / min in an oxygen atmosphere, and naturally cooled with the furnace. After that, it was crushed, sieved through 325 mesh, and demagnetized to obtain Mg, Al, and Zr co-doped Li 1.01 Ni 0.96 Co 0.03 Mn 0.01 O2 ultra-high nickel positive electrode material.

[0045] Example 2

[0046] This embodiment provides an ultra-high nickel ternary positive electrode material, and the preparation method of the ultra-high nickel ternary positive electrode material is as follows:

[0047] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 and battery-grade lithium hydroxide monohydrate are mixed in a high-speed mixer at a lithium to metal molar ratio of 1.01:1, and 0.1wt% of magnesium hydroxide, 0.1wt% of aluminum oxide, 0.05wt% of zirconium oxide, and 0.05wt% of yttrium oxide are added to the ternary precursor. The mixture is heated at 700°C in an oxygen atmosphere at a heating rate of 2°C / min for 10 hours, and naturally cooled in the furnace. After that, it is crushed, sieved through 325 mesh, and demagnetized to obtain a primary sintered material for the ultra-high nickel positive electrode material.

[0048] (2) The primary sintered material was mixed evenly with glycine and aluminum glycinate in an amount of 0.3 wt% of the primary sintered material, and then kept at 450 ° C for 6 h at a heating rate of 2 ° C / min in an oxygen atmosphere, and naturally cooled with the furnace. After that, it was crushed, sieved through 325 mesh, and demagnetized to obtain Mg, Al, Zr, and Y co-doped Li 1.01 Ni 0.96 Co 0.03 Mn 0.01 O2 ultra-high nickel positive electrode material.

[0049] Example 3

[0050] This embodiment provides an ultra-high nickel ternary positive electrode material, and the preparation method of the ultra-high nickel ternary positive electrode material is as follows:

[0051] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 and battery-grade lithium hydroxide monohydrate are mixed in a high-speed mixer at a lithium to metal molar ratio of 1.01:1, and 0.1wt% of magnesium hydroxide, 0.2wt% of aluminum oxide, 0.1wt% of zirconium oxide, and 0.05wt% of yttrium oxide are added to the ternary precursor. The mixture is heated at 700°C in an oxygen atmosphere at a heating rate of 2°C / min for 10 hours, and naturally cooled in the furnace. After that, the mixture is crushed, sieved through 325 mesh, and demagnetized to obtain a primary sintered material for an ultra-high nickel positive electrode material.

[0052] (2) The primary sintered material was mixed evenly with glycine and glycinate aluminum zirconium in an amount of 0.3 wt% of the primary sintered material, and then heated at 450 ° C for 6 h at a heating rate of 2 ° C / min in an oxygen atmosphere, and naturally cooled with the furnace. After that, it was crushed, sieved through 325 mesh, and demagnetized to obtain Mg, Al, Zr, and Y co-doped Li 1.01 Ni 0.96 Co 0.03 Mn 0.01 O2 ultra-high nickel positive electrode material.

[0053] Example 4

[0054] This embodiment provides an ultra-high nickel ternary positive electrode material, and the preparation method of the ultra-high nickel ternary positive electrode material is as follows:

[0055] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 and battery-grade lithium hydroxide monohydrate are mixed in a high-pressure mixer at a lithium to metal molar ratio of 1.01:1, and 0.1wt% of magnesium hydroxide, 0.2wt% of aluminum oxide, 0.1wt% of zirconium oxide, 0.05wt% of yttrium oxide, and 0.1wt% of tungsten oxide are added to the ternary precursor. The mixture is heated at 700°C in an oxygen atmosphere at a heating rate of 2°C / min for 10 hours, and naturally cooled with the furnace. After that, the mixture is crushed, sieved through 325 mesh, and demagnetized to obtain a primary sintered material for an ultra-high nickel positive electrode material.

[0056] (2) The primary sintered material was mixed evenly with glycine and glycinate aluminum zirconium in an amount of 0.3 wt% of the primary sintered material, and then kept at 450 ° C for 6 h at a heating rate of 2 ° C / min in an oxygen atmosphere, and naturally cooled with the furnace. After that, it was crushed, sieved through 325 mesh, and demagnetized to obtain Mg, Al, Zr, Y, and W co-doped Li 1.01 Ni 0.96 Co 0.03 Mn 0.01 O2 ultra-high nickel positive electrode material.

[0057] The SEM image of the ultra-high nickel positive electrode material is as follows Figure 1 shown.

[0058] Example 5

[0059] This embodiment provides an ultra-high nickel ternary positive electrode material, and the preparation method of the ultra-high nickel ternary positive electrode material is as follows:

[0060] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 and battery-grade lithium hydroxide monohydrate are mixed in a high-pressure mixer at a lithium to metal molar ratio of 1.01:1, and 0.2wt% of magnesium hydroxide, 0.1wt% of aluminum oxide, 0.05wt% of zirconium oxide, 0.05wt% of yttrium oxide, and 0.1wt% of tungsten oxide are added to the ternary precursor. The mixture is heated at 710°C in an oxygen atmosphere at a heating rate of 2°C / min for 10 hours, and naturally cooled with the furnace. After that, the mixture is crushed, sieved through 325 mesh, and demagnetized to obtain a primary sintered material for an ultra-high nickel positive electrode material.

[0061] (2) The primary sintered material was mixed evenly with glycine and glycinate aluminum zirconium in an amount of 0.3 wt% of the primary sintered material, and then kept at 450 ° C for 6 h at a heating rate of 2 ° C / min in an oxygen atmosphere, and naturally cooled with the furnace. After that, it was crushed, sieved through 325 mesh, and demagnetized to obtain Mg, Al, Zr, Y, and W co-doped Li 1.01 Ni 0.96 Co 0.03 Mn 0.01 O2 ultra-high nickel positive electrode material.

[0062] Example 6

[0063] This embodiment provides an ultra-high nickel ternary positive electrode material, and the preparation method of the ultra-high nickel ternary positive electrode material is as follows:

[0064] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 and battery-grade lithium hydroxide monohydrate are mixed in a high-pressure mixer at a lithium to metal molar ratio of 1.01:1, and 0.2wt% of magnesium hydroxide, 0.2wt% of aluminum oxide, 0.15wt% of zirconium oxide, 0.1wt% of yttrium oxide, and 0.1wt% of tungsten oxide are added as a ternary precursor. The mixture is heated at 710°C in an oxygen atmosphere at a heating rate of 2°C / min for 10 hours, and naturally cooled with the furnace. After that, the mixture is crushed, sieved through 325 mesh, and demagnetized to obtain a primary sintered material for an ultra-high nickel positive electrode material.

[0065] (2) The primary sintered material was mixed evenly with glycine and glycinate aluminum zirconium in an amount of 0.3 wt% of the primary sintered material, and then kept at 450 ° C for 6 h at a heating rate of 2 ° C / min in an oxygen atmosphere, and naturally cooled with the furnace. After that, it was crushed, sieved through 325 mesh, and demagnetized to obtain Mg, Al, Zr, Y, and W co-doped Li 1.01 Ni 0.96 Co 0.03 Mn 0.01 O2 ultra-high nickel positive electrode material.

[0066] Example 7

[0067] The only difference between this embodiment and embodiment 4 is that the total mass of glycine and aluminum glycinate is 0.05% of the calcined material, and the other conditions and parameters are exactly the same as those in embodiment 4.

[0068] Example 8

[0069] The only difference between this embodiment and embodiment 4 is that the total mass of glycine and aluminum glycinate is 4% of the calcined material, and the other conditions and parameters are exactly the same as those in embodiment 4.

[0070] Example 9

[0071] The only difference between this embodiment and embodiment 4 is that the temperature of the heat treatment in step (2) is 250° C., and the other conditions and parameters are exactly the same as those in embodiment 4.

[0072] Example 10

[0073] The only difference between this embodiment and embodiment 4 is that the temperature of the heat treatment in step (2) is 650° C., and the other conditions and parameters are exactly the same as those in embodiment 4.

[0074] Comparative Example 1

[0075] This comparative example provides an ultra-high nickel ternary positive electrode material, and the preparation method of the ultra-high nickel ternary positive electrode material is as follows:

[0076] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 and battery-grade lithium hydroxide monohydrate were mixed in a high-pressure mixer at a lithium to metal molar ratio of 1.01:1, and magnesium hydroxide (0.1 wt% of the mass of the ternary precursor) was added. The mixture was heated at 700°C for 10 hours at a heating rate of 2°C / min in an oxygen atmosphere, and naturally cooled in the furnace. The mixture was then crushed, sieved through 325 mesh, and demagnetized to obtain a primary sintered material for the ultra-high nickel positive electrode material.

[0077] (2) The primary sintered material was mixed evenly with 0.1 wt% of alumina and 0.1 wt% of zirconia, and then heated at 450 ° C for 6 h at a heating rate of 2 ° C / min in an oxygen atmosphere, and naturally cooled with the furnace. After that, it was crushed, sieved through 325 mesh, and demagnetized to obtain Mg-doped Li 1.01 Ni 0.96 Co 0.03 Mn 0.01 O2 ultra-high nickel positive electrode material.

[0078] The SEM image of the ultra-high nickel positive electrode material is as follows Figure 2 shown.

[0079] Comparative Example 2

[0080] This comparative example provides an ultra-high nickel ternary positive electrode material, and the preparation method of the ultra-high nickel ternary positive electrode material is as follows:

[0081] (1) Ni 0.96 Co 0.03 Mn 0.01(OH)2 and battery-grade lithium hydroxide monohydrate are mixed in a high-pressure mixer at a lithium to metal molar ratio of 1.01:1, and 0.1wt% of magnesium hydroxide and 0.1wt% of aluminum oxide are added. The mixture is heated at 700°C for 10 hours at a heating rate of 2°C / min in an oxygen atmosphere, and naturally cooled in the furnace. After that, the mixture is crushed, sieved through 325 mesh, and demagnetized to obtain a primary sintered material for an ultra-high nickel positive electrode material.

[0082] (2) The primary sintered material was mixed evenly with glycine, 0.1 wt% alumina and 0.1 wt% zirconia in an amount of 0.3 wt% of the primary sintered material, and then kept at 450 ° C for 6 h at a heating rate of 2 ° C / min in an oxygen atmosphere, and naturally cooled with the furnace. After that, it was crushed, sieved through 325 mesh, and demagnetized to obtain Mg, Al co-doped Li 1.01 Ni 0.96 Co 0.03 Mn 0.01 O2 ultra-high nickel positive electrode material.

[0083] Comparative Example 3

[0084] The only difference between this comparative example and Example 4 is that glycine and aluminum glycinate are replaced with graphene, and the other conditions and parameters are exactly the same as those in Example 4.

[0085] Performance testing:

[0086] 1. Take the positive electrode materials obtained in Examples 1-10 and Comparative Examples 1-3 and weigh the three materials in a ratio of 96.9 (positive electrode material): 1.6 (binder PVDF): 1.5 (conductive agent SP);

[0087] 2. Add dispersant NMP and mix evenly in a homogenizer to make slurry, then use a coating machine to coat it on the conductive aluminum foil (surface density 15.0 ~ 17.0 mg / cm 2 );

[0088] 3. Place in a 100℃ forced air drying oven and dry for 2 hours, then cut into 13mm diameter pole pieces, weigh, and vacuum bake at 140℃ for 3 hours;

[0089] 4. Assemble CR2032 button cells in an argon glove box using lithium metal as the negative electrode;

[0090] At room temperature, the button cell was placed in a Blue Electric test system for charge and discharge testing. The charge and discharge test parameters were set as follows: voltage range 2.5V-4.25V, 0.2C / 0.2C→0.5C / 1C→0.5C / 1C cycles 50 times. The test results are shown in Table 1:

[0091] Table 1

[0092]

[0093]

[0094] As can be seen from Table 1, from Examples 1-10, the battery made of the positive electrode material of the present invention has a first-week charge capacity of more than 244.3 mAh / g, a first-week discharge capacity of more than 216.3 mAh / g, a first-week coulombic efficiency of more than 88.9%, a capacity retention rate of more than 88.9% after 50 cycles, and a 1C discharge capacity of more than 200.2 mAh / g.

[0095] From the comparison between Example 1 and Examples 2-6, it can be seen that in the ultra-high nickel ternary positive electrode material of the present invention, Mg 2+ Due to its low valence and similar ionic radius to Li+, it can enter the main material lattice and occupy the Li layer, stabilizing the structure of the material. 3+ It is easier to incorporate lattice-stabilized structure and reduce the degree of cation mixing. Although the addition of Mg and Al reduces the initial capacity of the material, the appropriate amount of Mg and Al doping can significantly improve the cycle performance and thermal stability of the material; the addition of Zr can make up for the problem of reduced initial capacity caused by Mg and Al doping. A small amount of Zr 4+ Entering the crystal lattice can stabilize the lithium ion diffusion channel, enrich more on the surface of the material to form a fast ion conductor, optimize the grain boundary, increase the lithium ion conductivity and improve the DCR of the material; 3+ Due to the increase in ion radius, the incorporation into the lattice will cause the increase in the material unit cell parameters and the unit cell volume, thereby increasing the volume of the lithium ion transmission path, further increasing the diffusion rate of lithium ions, inhibiting phase change under high voltage, and improving the thermal stability of the material. At the same time, it can also improve the rate performance of the material and have good electrochemical reversibility; the W element can refine the grains, improve the morphology of the material, and enhance the cycle performance of the material.

[0096] By comparison of Example 4 and Example 7-8, it can be seen that in the preparation process of the ultra-high nickel ternary positive electrode material of the present invention, the mass ratio of the glycine source and the calcined material affects the performance of the obtained positive electrode material, and the mass ratio of the glycine source and the calcined material is controlled at (0.1-3): 100, and the obtained positive electrode material has better performance. If the mass ratio of the glycine source and the calcined material is too small, the residual alkali of the material cannot be effectively reduced, the residual alkali content is too high, and it is easy to react with the electrolyte to increase gas production, thereby reducing the safety performance of the battery core. At the same time, the coating amount is low, resulting in an inability to form a protective coating on the surface of the particles, which is easily corroded by the electrolyte and causes metal dissolution, thereby reducing the cycle stability of the ultra-high nickel positive electrode material; if the mass ratio of the glycine source and the calcined material is too large, although the residual alkali level of the material can be significantly reduced, the coating additive amount is too high, resulting in a thickening of the coating layer, a longer transmission distance of lithium ions, an increase in impedance, and further reducing the rate and cycle performance of the material.

[0097] By comparing Example 4 with Examples 9-10, it can be seen that in the preparation process of the ultra-high nickel ternary positive electrode material of the present invention, the temperature of the heat treatment will affect the performance of the obtained positive electrode material. The heat treatment temperature is controlled at 300-600°C, and the performance of the obtained positive electrode material is better. If the heat treatment temperature is too low, the glycine source additive cannot be melted well, which is not conducive to the reduction of residual alkali, resulting in the formation of an uneven protective coating on the surface of the particles, affecting the cycle performance of the material. At the same time, insufficient decomposition of glycine will result in carbon residue, which will affect the capacity. If the heat treatment temperature is too high, the glycine source additive decomposes too quickly and the residual alkali cannot be reduced well. At the same time, the high temperature causes the grain size of the material to become larger, hindering the transmission of lithium ions and reducing the rate performance of the material.

[0098] By comparing Example 1 and Comparative Examples 1-2, it can be seen that the present invention prepares an ultra-high nickel ternary positive electrode material by a solid-phase sintering method, adds at least three metal ion additives, fully utilizes the various properties of the metal ions in the additives, matches the various metal ions, improves the cycle performance and thermal stability of the material, and comprehensively improves the electrochemical properties of the ultra-high nickel positive electrode material.

[0099] From the comparison between Example 1 and Comparative Example 3, it can be seen that the present invention utilizes the acidic functional group of glycine to react with the lithium source on the surface of the primary sintered product to produce an acid-base neutralization reaction, thereby reducing the residual alkali content on the surface of the positive electrode material. Glycine is directly mixed with a sintered material instead of being used as an additive for water washing or alcohol washing to acid-wash the material. This avoids direct corrosion of the surface of the positive electrode material by water washing or alcohol washing, which promotes the dissolution of metals such as lithium and causes loss of capacity, and at the same time avoids damage to the surface structure of the material by water washing or alcohol washing. In addition, the addition of glycine salts such as glycinate aluminum and glycinate aluminum zirconium also has a positive effect on coating the surface of the positive electrode material to form a protective coating. The molten organic acid salt can react with the residual alkali (OH) on the surface of the sintered product. - 、CO32- ) reacts and is removed, so that the free lithium on the surface combines with other coated elements (Al or Zr, etc.) to form a lithium salt compound, forming a protective coating on the surface of the positive electrode material, which greatly reduces the residual alkali on the surface of the material. At the same time, it can effectively isolate the electrolyte from the corrosion of the inside of the material, inhibit the occurrence of side reactions, and has a stable structure, improved thermal stability, reduced impedance, and improved material circulation functions.

[0100] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing an ultra-high nickel ternary positive electrode material, characterized in that: The preparation method comprises the following steps: (1) mixing an ultra-high nickel ternary precursor, a lithium source and an additive, and sintering the mixture to obtain a sintered material; (2) mixing a calcined material and a glycine source, and obtaining the ultra-high nickel ternary positive electrode material after heat treatment; Wherein, the additive in step (1) comprises a combination of any three or at least four of aluminum oxide, magnesium hydroxide, zirconium oxide, yttrium oxide or tungsten oxide; The glycine source in step (2) comprises glycine and a glycine salt; the glycine salt comprises any one of glycinate aluminum, glycinate magnesium or glycinate aluminum zirconium, or a combination of at least two thereof; The mass ratio of the glycine source and the calcined material in step (2) is (0.1-5):100; The temperature of the heat treatment in step (2) is 250-600°C.

2. The preparation method according to claim 1, wherein The chemical formula of the ultra-high nickel ternary precursor in step (1) is Ni x Co y Mn z (OH)2; wherein, x+y+z=1, 0.95≤x<1, 0.01≤y≤0.1, 0.01≤z≤0.

1.

3. The preparation method according to claim 1, wherein The lithium source includes lithium hydroxide and / or lithium carbonate.

4. The preparation method according to claim 1, wherein The ratio of the molar amount of the lithium element in the lithium source to the total molar amount of the metal elements in the ultra-high nickel ternary precursor is (1.01-1.1):

1.

5. The preparation method according to claim 1, wherein The additives in step (1) include aluminum oxide, magnesium hydroxide, zirconium oxide, yttrium oxide and tungsten oxide.

6. The preparation method according to claim 5, wherein The mass ratio of the magnesium hydroxide to the ultra-high nickel ternary precursor is (0.1-0.4):

100.

7. The preparation method according to claim 5, wherein The mass ratio of the aluminum oxide to the ultra-high nickel ternary precursor is (0.1-0.4):

100.

8. The preparation method according to claim 5, wherein The mass ratio of the yttrium oxide to the ultra-high nickel ternary precursor is (0.05-0.3):

100.

9. The preparation method according to claim 5, wherein The mass ratio of the zirconium oxide to the ultra-high nickel ternary precursor is (0.05-0.3):

100.

10. The preparation method according to claim 5, characterized in that The mass ratio of the tungsten oxide to the ultra-high nickel ternary precursor is (0.05-0.3):

100.

11. The preparation method according to claim 1, wherein The temperature of the sintering treatment in step (1) is 600-900°C.

12. The preparation method according to claim 11, characterized in that The temperature of the sintering treatment in step (1) is 650-750°C.

13. The preparation method according to claim 1, wherein The sintering treatment time is 8 to 24 hours.

14. The preparation method according to claim 13, wherein The sintering treatment time is 10 to 20 hours.

15. The preparation method according to claim 1, wherein The mass ratio of the glycine source and the calcined material in step (2) is (0.1-3):

100.

16. The preparation method according to claim 1, wherein The temperature of the heat treatment in step (2) is 300-600°C.

17. The preparation method according to claim 1, wherein The heat treatment time is 6 to 24 hours.

18. The preparation method according to claim 17, wherein The heat treatment time is 6 to 15 hours.

19. An ultra-high nickel ternary positive electrode material, characterized in that: The ultra-high nickel ternary positive electrode material is prepared by the method according to any one of claims 1 to 18, wherein the ultra-high nickel ternary positive electrode material comprises a core and a coating layer arranged on the surface of the core, and the chemical formula of the core is Li 1+y (Ni a Co b Mn 1-a-b-c B c ) 1-y O2, where 0≤y≤0.1, 0.95≤a<1, 0.01≤b≤0.1, 0≤c≤0.05, and B is Mg 2+ 、Al 3+ 、Zr 4+ 、Y 3+ or W 6+ A combination of any three or at least four of the following.

20. A positive electrode plate, characterized in that: The positive electrode plate comprises the ultra-high nickel ternary positive electrode material as claimed in claim 19.

21. A lithium ion battery, characterized in that: The lithium-ion battery comprises the positive electrode sheet according to claim 20.

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