CN115148987A - A kind of ultra-high nickel ternary positive electrode material and its preparation method and application - Google Patents

Abstract

The invention provides an ultrahigh nickel ternary cathode material and a preparation method and application thereof, wherein the preparation method comprises the following steps: (1) Mixing the ultrahigh nickel ternary precursor, a lithium source and an additive, and sintering to obtain a primary sintering material; (2) Mixing a calcined material and a glycine source, and carrying out heat treatment to obtain the ultra-high nickel ternary cathode material; the additive in the step (1) comprises any three or at least four of aluminum oxide, magnesium hydroxide, zirconium oxide, yttrium oxide and tungsten oxide, and the additive improves the structural stability of the ultra-high nickel material and improves the cycle performance of the material through multi-element doping modification; and meanwhile, the glycine source is coated, so that battery flatulence and corrosion of electrolyte to the interior of particles are avoided, impedance is reduced, and the circulation stability of the material is improved.

Description

A kind of ultra-high nickel ternary positive electrode material and preparation method and application thereof

technical field

The 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 technique

In recent years, the field of new energy has developed rapidly. As an efficient energy conversion and storage device, lithium-ion batteries are widely used in electric vehicles, portable electronic equipment and energy storage power stations. With the rapid development of electric vehicles in recent years, people have put forward higher requirements for the cruising range of electric vehicles and the energy density of lithium-ion batteries. The cathode materials of lithium-ion batteries for vehicles are developing in the direction of high nickel. Cathode materials have gradually become popular due to their high energy density and low cost.

However, with the further increase of the nickel content, especially the ultra-high nickel cathode material (0.95≤nickel content≤1), the extremely high nickel content not only increases the capacity of the cathode material, but also makes the material extremely sensitive to moisture and carbon dioxide. The high content of LiOH and Li ₂ CO ₃ on the surface will lead to the deterioration of the structural stability, cycle performance and safety performance of the cathode material, which in turn affects the overall performance of the cell. Among them, the residual alkali content is too high, and it is easy to have side reactions with the electrolyte to increase gas production, which reduces the safety performance of the cell; at the same time, the generation and expansion of micro-cracks during the cycle of the cell make the stress in all directions concentrated at the grain boundary, resulting in intergranular Cracking and particle breakage destroy the morphology and structure of the material, while the infiltration of electrolyte increases side reactions, increases impedance, affects the transport of lithium ions, and reduces structural stability and cycle performance.

CN113839015A discloses an ultra-high nickel-based single crystal positive electrode material and a preparation method thereof. It takes the precursor of ultra-high nickel cathode material (nickel-cobalt-manganese-aluminum hydroxide) as the matrix raw material, and fully smashes the precursor by using the force of high speed and high pressure, and adds lithium source and carbonic acid during this period. Strontium can promote the mutual dissolution of the lithium source and the precursor and the crystal co-growth at a lower temperature, reduce the mixing of lithium and nickel, and finally obtain a single-crystal-like material through calcination.

CN112310389A discloses a method for preparing an ultra-high nickel single crystal positive electrode material, comprising the following steps: S1. Mix a ternary precursor and lithium hydroxide with a molar ratio of lithium to metal of 1.01-1.10:1, and add doping calcined in an oxygen atmosphere to obtain primary calcined material; S2. pass the primary calcined material through coarse crushing, fine crushing, sieving, and demagnetization to obtain crushed material; S3. make the crushed material and water a ratio of water to material of 0.5:1 -5:1 is added to the reaction kettle, the temperature of the reaction kettle is controlled, and then the reagent is added to react, and after the reaction is completed, drying is carried out to obtain a mixture; S4. The mixture is mixed with the modified coating agent and placed in an atmosphere furnace for two Secondary calcination, then coarse crushing, fine crushing, sieving, and demagnetization, the ternary positive electrode material is obtained.

The ultra-high nickel cathode material described in the above scheme has the problems of poor cycle performance and high amount of residual alkali on the surface. Therefore, an ultra-high nickel cathode material with low residual alkali and high cycle stability is developed to improve the electrical performance of the material. It is very necessary to meet the application of power batteries in electric vehicles with chemical properties.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an ultra-high nickel ternary positive electrode material and a preparation method and application thereof. 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; Organic acid/organic acid salt, using glycine source to react with lithium source and other residual alkali on the surface of ultra-high nickel cathode material to remove, to avoid irreversible capacity loss and battery flatulence and other problems, while free lithium is bound to the material by combining with other elements of the coating A new lithium salt compound coating is formed on the surface, which can effectively avoid the corrosion of the electrolyte on the inside of the particles, reduce the impedance, and improve the cycle stability of the material.

In order to achieve this object of the invention, the present invention adopts the following technical solutions:

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:

(1) Mixing the ultra-high nickel ternary precursor, lithium source and additives, and sintering to obtain a sintered material;

(2) mixing a sintered material with a glycine source, and obtaining the ultra-high nickel ternary positive electrode material after heat treatment;

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

The invention prepares ultra-high nickel ternary positive electrode material by solid phase sintering method, adds at least three kinds of metal ion additives, makes full use of various characteristics of metal ions in the additives, matches various metal ions, and improves the cycle performance of the material and thermal stability, comprehensively improving the electrochemical performance of ultra-high nickel cathode materials.

In the present invention, a calcine material and a glycine source are mixed in a solid phase and then heat-treated. The glycine molecule has both acidic and basic functional groups, can be ionized in water, and has strong hydrophilicity, but belongs to non-polar amino acids and is soluble in polar amino acids. It is not soluble in non-polar solvents, and has high boiling and melting points. The present invention utilizes the acid-base neutralization reaction between the acidic functional group of glycine and the lithium source on the surface of the primary sintered product, thereby reducing the residual alkali content on the surface of the positive electrode material, and the glycine is directly mixed with the primary sintered material instead of being used as an additive for washing with water or alcohol. Pickling treatment of the material, which avoids the direct erosion of the surface of the positive electrode material by water washing or alcohol washing, and promotes the dissolution of lithium and other metals, which leads to the loss of capacity, and at the same time avoids the damage to the surface structure of the material by water washing or alcohol washing. The addition of glycinate also has a positive effect on the surface of the positive electrode material to form a protective coating, and the molten organic acid salt can react with the residual alkali (OH ^- , CO ₃ ^2- ) on the surface of the sintered product to remove it, so that the surface Free lithium combines with other coated elements (Al or Zr, etc.) to form a lithium salt compound, which forms a protective coating on the surface of the positive electrode material, which greatly reduces the residual alkali on the surface of the material, and can effectively isolate the corrosion of the interior of the material by the electrolyte. Suppresses the occurrence of side reactions, has a stable structure, improves thermal stability, reduces impedance, and improves material circulation.

Preferably, the chemical formula of the ultra-high nickel ternary precursor in step (1) is Ni _x Co _y M _z (OH) ₂ . Among them, 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.

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

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.

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

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.

Preferably, the mass ratio of the alumina 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.

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 Wait.

Preferably, the mass ratio of the zirconia 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 Wait.

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 Wait.

In the ultra-high nickel ternary cathode material of the present invention, Mg ²⁺ can enter the lattice of the host material and occupy the Li layer due to its low price and similar ionic radius to Li+, stabilizing the structure of the material, and also Al ³⁺ is easier to dope Into the lattice to stabilize the structure and reduce the degree of cation mixing. Although the addition of Mg and Al reduces the initial capacity of the material, an appropriate amount of Mg and Al doping can significantly improve the cycle performance and thermal stability of the material; and the addition of Zr can Make up for the problem of initial capacity reduction caused by Mg and Al doping, a small amount of Zr ⁴⁺ entering the lattice can stabilize the lithium ion diffusion channel, and more enrichment on the surface of the material to form fast ion conductors, optimize grain boundaries, and improve lithium ion conductivity The DCR rate of the material is improved; the incorporation of Y ³⁺ into the crystal lattice will cause the increase of the unit cell parameters of the material and the increase of the unit cell volume due to the increase of the ionic radius, so that the volume of the lithium ion transport pathway also increases, which further improves the The diffusion rate of lithium ions can inhibit the phase transition under high voltage, improve the thermal stability of the material, and also improve the rate performance of the material, with good electrochemical reversibility; W element can refine the grains and improve the shape of the material. appearance and improve the cycle performance of the material.

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, etc., preferably 650-750°C.

Preferably, the time of the sintering treatment is 8-24h, for example: 8h, 10h, 12h, 16h, 20h or 24h, etc., preferably 10-20h.

Preferably, the glycine source in step (2) includes glycine and/or glycine salt.

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

Preferably, the mass ratio of the glycine source described in step (2) and the primary calcine material 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 to 3): 100.

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, etc., preferably 300-600°C.

Preferably, the heat treatment time is 6-24h, for example: 6h, 10h, 12h, 16h, 20h or 24h, etc., preferably 6-15h.

In a second aspect, the present invention provides an ultra-high nickel ternary positive electrode material, the ultra-high nickel ternary positive electrode material is prepared by the method described in the first aspect, and the ultra-high nickel ternary positive electrode material comprises an inner core and a A coating layer disposed on the surface of the inner core, the chemical formula of the inner core is Li _1+y (Ni _a Co _b Mn _1-abc B _c ) _1-y O ₂ , wherein 0≤y≤0.1, for example: 0 , 0.01, 0.02, 0.05, 0.08, or 0.1, etc., 0.95≤a≤1, such as: 0.95, 0.96, 0.97, 0.98, or 0.99, etc., 0.01≤b≤0.1, such as: 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 any one or at least two of Mg ²⁺ , Al ³⁺ , Zr ⁴⁺ , Y ³⁺ or W ⁶⁺ combination.

In a third aspect, the present invention provides a positive electrode piece, the positive electrode piece comprising the ultra-high nickel ternary positive electrode material as described in the second aspect.

In a fourth aspect, the present invention provides a lithium ion battery, the lithium ion battery comprising the positive electrode plate according to the third aspect.

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

(1) The present invention prepares ultra-high nickel ternary positive electrode material by solid phase sintering method, adds additives of at least three kinds of metal ions, makes full use of various characteristics of metal ions in the additives, matches various metal ions, and improves the performance of materials. It comprehensively improves the electrochemical performance of ultra-high nickel cathode materials, and uses the acidic functional group of glycine to undergo acid-base neutralization reaction with the lithium source on the surface of the primary sintered product, thereby reducing the residual alkali content on the surface of the cathode material. , Glycine is directly mixed with a sintered material, which avoids the direct erosion of the surface of the positive electrode material by water or alcohol washing and promotes the dissolution of lithium and other metals, resulting in the loss of capacity, and at the same time avoids the destruction of the surface structure of the material by water washing or alcohol washing. In addition, aluminum glycine, glycine The addition of glycinate such as aluminum zirconium also has a positive effect on the surface of the positive electrode material to form a protective coating, and the molten organic acid salt can react with the residual alkali (OH ^- , CO ₃ ^2- ) on the surface of the sintered product to remove it, so that the The free lithium on the surface combines with other coated elements (Al or Zr, etc.) to form a lithium salt compound, which forms a protective coating on the surface of the positive electrode material, which greatly reduces the residual alkali on the surface of the material, and can effectively isolate the electrolyte from the inside of the material. Erosion, inhibits the occurrence of side reactions, has a stable structure, improves thermal stability, reduces impedance, and improves material circulation.

(2) The specific capacity of the battery made of the positive electrode material of the present invention can reach more than 244.3mAh/g in the first week, the specific capacity of discharge in the first week can reach more than 216.3mAh/g, and the coulombic efficiency in the first week can reach more than 88.9%, The capacity retention rate after 50 cycles can reach more than 88.9%, and the specific capacity of 1C discharge can reach more than 200.2mAh/g.

Description of drawings

1 is a SEM image of the ultra-high nickel cathode material described in Example 4.

FIG. 2 is a SEM image of the ultra-high nickel cathode material described in Comparative Example 1. FIG.

Detailed ways

The technical solutions of the present invention are further described below through specific embodiments. It should be understood by those skilled in the art that the embodiments are only for helping the understanding of the present invention, and should not be regarded as a specific limitation of the present invention.

Example 1

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:

(1) Mix Ni _0.96 Co _0.03 Mn _0.01 (OH) ₂ and battery-grade lithium hydroxide monohydrate in a high-mixer at a molar ratio of lithium to metal of 1.01:1, and add 0.1 wt % of ternary precursor mass Magnesium hydroxide, 0.1wt% alumina, 0.05wt% zirconia were kept at 700°C for 10h at a heating rate of 2°C/min in an oxygen atmosphere, cooled naturally with the furnace, and then crushed, sieved with 325 mesh, demagnetized , to obtain the primary sintered material of ultra-high nickel cathode material;

(2) Mix the primary sintering material with 0.3 wt% glycine and 0.1 wt% aluminum glycinate, and then keep the temperature at 450°C for 6 hours at a heating rate of 2°C/min in an oxygen atmosphere, and then keep the temperature in the furnace with the furnace. Naturally cooled, then crushed, sieved with 325 mesh, and demagnetized to obtain a Li _1.01 Ni _0.96 Co _0.03 Mn _0.01 O ₂ ultra-high nickel cathode material co-doped with Mg, Al, and Zr.

Example 2

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:

(1) Mix Ni _0.96 Co _0.03 Mn _0.01 (OH) ₂ and battery-grade lithium hydroxide monohydrate in a high-mixer at a molar ratio of lithium to metal of 1.01:1, and add 0.1 wt % of ternary precursor mass Magnesium hydroxide, 0.1wt% alumina, 0.05wt% zirconia, and 0.05wt% yttria were kept at 700°C for 10h in an oxygen atmosphere at a heating rate of 2°C/min, cooled naturally with the furnace, and then crushed, 325 mesh sieve and demagnetization to obtain primary sintered material of ultra-high nickel cathode material;

(2) Mix the primary sintering material with 0.3 wt% glycine and 0.1 wt% aluminum glycinate, and then keep the temperature at 450°C for 6 hours at a heating rate of 2°C/min in an oxygen atmosphere, and then keep the temperature in the furnace with the furnace. Naturally cooled, then pulverized, sieved with 325 mesh, and demagnetized to obtain a Li _1.01 Ni _0.96 Co _0.03 Mn _0.01 O ₂ ultra-high nickel cathode material co-doped with Mg, Al, Zr, and Y.

Example 3

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:

(1) Mix Ni _0.96 Co _0.03 Mn _0.01 (OH) ₂ and battery-grade lithium hydroxide monohydrate in a high-mixer at a molar ratio of lithium to metal of 1.01:1, and add 0.1 wt % of ternary precursor mass Magnesium hydroxide, 0.2wt% alumina, 0.1wt% zirconia, and 0.05wt% yttria were kept at 700°C for 10h in an oxygen atmosphere at a heating rate of 2°C/min, cooled naturally with the furnace, and then crushed, 325 mesh sieve and demagnetization to obtain primary sintered material of ultra-high nickel cathode material;

(2) Mix the primary sintering material with 0.3wt% glycine and 0.1wt% glycine aluminum zirconium, and then keep the temperature at 450°C for 6h at a heating rate of 2°C/min in an oxygen atmosphere. The furnace is cooled naturally, and then pulverized, sieved with 325 mesh, and demagnetized to obtain a Li _1.01 Ni _0.96 Co _0.03 Mn _0.01 O ₂ ultra-high nickel cathode material co-doped with Mg, Al, Zr, and Y.

Example 4

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:

(1) Mix Ni _0.96 Co _0.03 Mn _0.01 (OH) ₂ and battery-grade lithium hydroxide monohydrate in a high-mixer at a molar ratio of lithium to metal of 1.01:1, and add 0.1 wt % of ternary precursor mass Magnesium hydroxide, 0.2wt% alumina, 0.1wt% zirconia, 0.05wt% yttrium oxide, 0.1wt% tungsten oxide were kept at 700°C for 10h in an oxygen atmosphere at a heating rate of 2°C/min, followed by the furnace. Naturally cooled, then crushed, sieved with 325 mesh, and demagnetized to obtain primary sintered material of ultra-high nickel cathode material;

(2) Mix the primary sintering material with 0.3wt% glycine and 0.1wt% glycine aluminum zirconium, and then keep the temperature at 450°C for 6h at a heating rate of 2°C/min in an oxygen atmosphere. The furnace was cooled naturally, and then crushed, sieved with 325 mesh, and demagnetized to obtain a Li _1.01 Ni _0.96 Co _0.03 Mn _0.01 O ₂ ultra-high nickel cathode material co-doped with Mg, Al, Zr, Y, and W.

The SEM image of the ultra-high nickel cathode material is shown in FIG. 1 .

Example 5

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:

(1) Mix Ni _0.96 Co _0.03 Mn _0.01 (OH) ₂ and battery-grade lithium hydroxide monohydrate in a high-mixer at a molar ratio of lithium to metal of 1.01:1, and add 0.2wt% of ternary precursor mass Magnesium hydroxide, 0.1wt% alumina, 0.05wt% zirconia, 0.05wt% yttrium oxide, 0.1wt% tungsten oxide were kept at 710°C for 10h in an oxygen atmosphere at a heating rate of 2°C/min, and the furnace Naturally cooled, then pulverized, sieved with 325 mesh, and demagnetized to obtain primary sintered material of ultra-high nickel cathode material;

(2) Mix the primary sintering material with 0.3wt% glycine and 0.1wt% glycine aluminum zirconium, and then keep the temperature at 450°C for 6h at a heating rate of 2°C/min in an oxygen atmosphere. The furnace was cooled naturally, and then crushed, sieved with 325 mesh, and demagnetized to obtain a Li _1.01 Ni _0.96 Co _0.03 Mn _0.01 O ₂ ultra-high nickel cathode material co-doped with Mg, Al, Zr, Y, and W.

Example 6

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:

(1) Mix Ni _0.96 Co _0.03 Mn _0.01 (OH) ₂ and battery-grade lithium hydroxide monohydrate in a high-mixer at a molar ratio of lithium to metal of 1.01:1, and add 0.2wt% of ternary precursor mass Magnesium hydroxide, 0.2wt% alumina, 0.15wt% zirconia, 0.1wt% yttrium oxide, 0.1wt% tungsten oxide were kept at 710°C in an oxygen atmosphere for 10h at a heating rate of 2°C/min. Naturally cooled, then crushed, sieved with 325 mesh, and demagnetized to obtain primary sintered material of ultra-high nickel cathode material;

(2) Mix the primary sintering material with 0.3wt% glycine and 0.1wt% glycine aluminum zirconium, and then keep the temperature at 450°C for 6h at a heating rate of 2°C/min in an oxygen atmosphere. The furnace was cooled naturally, and then crushed, sieved with 325 mesh, and demagnetized to obtain a Li _1.01 Ni _0.96 Co _0.03 Mn _0.01 O ₂ ultra-high nickel cathode material co-doped with Mg, Al, Zr, Y, and W.

Example 7

The only difference between this example and Example 4 is that the total mass of glycine and aluminum glycinate is 0.05% of the primary calcined material, and other conditions and parameters are exactly the same as those of Example 4.

Example 8

The only difference between this example and Example 4 is that the total mass of glycine and aluminum glycinate is 4% of the primary calcined material, and other conditions and parameters are exactly the same as those of Example 4.

Example 9

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

Example 10

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

Comparative Example 1

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:

(1) Mix Ni _0.96 Co _0.03 Mn _0.01 (OH) ₂ and battery-grade lithium hydroxide monohydrate in a high-mixer at a molar ratio of lithium to metal of 1.01:1, and add 0.1 wt % of ternary precursor mass Magnesium hydroxide, kept at 700°C for 10h at a heating rate of 2°C/min in an oxygen atmosphere, cooled naturally with the furnace, and then crushed, sieved with 325 mesh, and demagnetized to obtain a primary sintered material for ultra-high nickel cathode materials;

(2) Mix the primary sintering material uniformly with alumina and 0.1 wt% zirconia in an amount of 0.1 wt% of the mass of the primary sintering material, and then keep the temperature at 450°C for 6 hours at a heating rate of 2°C/min in an oxygen atmosphere, and then keep the temperature at a rate of 2°C/min for 6 hours. The furnace is cooled naturally, and then crushed, sieved with 325 mesh, and demagnetized to obtain a Mg-doped Li _1.01 Ni _0.96 Co _0.03 Mn _0.01 O ₂ ultra-high nickel cathode material.

The SEM image of the ultra-high nickel cathode material is shown in FIG. 2 .

Comparative Example 2

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:

(1) Mix Ni _0.96 Co _0.03 Mn _0.01 (OH) ₂ and battery-grade lithium hydroxide monohydrate in a high-mixer at a molar ratio of lithium to metal of 1.01:1, and add 0.1 wt % of ternary precursor mass Magnesium hydroxide and 0.1wt% alumina were kept at 700°C for 10h at a heating rate of 2°C/min in an oxygen atmosphere, cooled naturally with the furnace, and then crushed, sieved with 325 mesh, and demagnetized to obtain an ultra-high nickel positive electrode Material one-time sintering material;

(2) Mix the primary sintering material with 0.3 wt % glycine, 0.1 wt % alumina and 0.1 wt % zirconium oxide added in the mass of the primary sintering material, and then in an oxygen atmosphere at 450° C. at a temperature of 2° C./min. The heating rate was maintained for 6 hours, followed by natural cooling in the furnace, followed by pulverization, 325-mesh sieving, and demagnetization to obtain a Li _1.01 Ni _0.96 Co _0.03 Mn _0.01 O ₂ ultra-high nickel cathode material co-doped with Mg and Al.

Comparative Example 3

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

Performance Testing:

1. Take the positive electrode material obtained from Example 1-10 and Comparative Example 1-3, and weigh three materials at the ratio of 96.9 (positive electrode material): 1.6 (binder PVDF): 1.5 (conducting agent SP);

2. Add dispersant NMP and mix it in a homogenizer to make a slurry, and then use a coating machine to coat it on a flat conductive aluminum foil (area density 15.0-17.0 mg/cm ² );

3. Put it in a blast drying oven at 100°C for 2 hours, then cut it into a 13mm diameter pole piece, weigh it, and bake it in a vacuum at 140°C for 3 hours;

4. Using lithium metal as the negative electrode, assemble the CR2032 button battery in an argon gas glove box;

Put the button battery into the blue electricity test system at room temperature for charge and discharge test. The charging and discharging test parameters are set as: voltage range 2.5V-4.25V, 0.2C/0.2C→0.5C/1C→0.5C/1C cycle 50 times, the test results are shown in Table 1:

Table 1

It can be seen from Table 1 that from Examples 1-10, the first-week charge specific capacity of the battery made of the positive electrode material of the present invention can reach more than 244.3mAh/g, and the first-week discharge specific capacity can reach 216.3mAh/g. g or more, the Coulombic efficiency in the first week can reach more than 88.9%, the capacity retention rate after 50 cycles can reach more than 88.9%, and the 1C discharge specific capacity can reach more than 200.2mAh/g.

From the comparison between Example 1 and Examples 2-6, it can be seen that in the ultra-high nickel ternary cathode material of the present invention, Mg ²⁺ can enter the lattice of the host material and occupy Li due to its low price and similar ionic radius to Li+. layer, stabilizes the structure of the material, and also Al ³⁺ is easier to incorporate into the lattice-stabilized structure, reducing the degree of cation mixing. Although the addition of Mg and Al reduces the initial capacity of the material, an appropriate amount of Mg and Al doping can significantly improve the The cycle performance and thermal stability of the material; the addition of Zr can make up for the problem of initial capacity reduction caused by Mg and Al doping, a small amount of Zr ⁴⁺ entering the lattice can stabilize the lithium ion diffusion channel, and more enrichment in the material The surface forms fast ion conductors, optimizes grain boundaries, improves lithium ion conductivity, and improves the DCR of the material; due to the increase in the ionic radius of Y ³⁺ , the incorporation of the crystal lattice will cause the increase of the unit cell parameters of the material and the increase of the unit cell volume, thereby making the The volume of the lithium ion transport pathway also increases, which further improves the diffusion rate of lithium ions, suppresses the phase transition under high voltage, improves the thermal stability of the material, and also improves the rate capability of the material, with good electrochemical reversibility. The W element can refine the grains, improve the morphology of the material, and improve the cycle performance of the material.

From the comparison of Example 4 and Examples 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 primary calcined material will affect the performance of the prepared positive electrode material, and the glycine The mass ratio of the source and the first-fired material is controlled at (0.1-3):100, and the obtained positive electrode material has good performance. If the mass ratio of the glycine source and the primary calcined material is too small, the residual alkali of the material cannot be effectively reduced, and the residual alkali content is too high, it is easy to have side reactions with the electrolyte and the gas production increases, reducing the safety performance of the battery, and at the same time including The low coating amount leads to the inability to form a protective coating on the surface of the particles, which is easily eroded by the electrolyte to dissolve the metal and reduce the cycle stability of the ultra-high nickel cathode material; Although the residual alkali level of the material can be significantly reduced, the excessive amount of coating additives leads to the thickening of the coating layer, the transmission distance of lithium ions becomes longer, and the impedance increases, which further reduces the rate and cycle performance of the material.

From the comparison of Example 4 and 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 heat treatment will affect the performance of the obtained positive electrode material, and the temperature of heat treatment is controlled at 300～ At 600 °C, the performance of the prepared cathode material is good. 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, which affects the cycle of the material. At the same time, if the decomposition of glycine is insufficient, there will be carbon residue, which will affect the performance of the capacity; if the heat treatment temperature is too high, the glycine source additive will decompose too fast, and the residual alkali cannot be reduced well. At the same time, the temperature is too high to make the material grain size. becomes larger, hindering the transport of lithium ions and reducing the rate capability of the material.

From the comparison of Example 1 and Comparative Examples 1-2, it can be seen that the present invention prepares ultra-high nickel ternary positive electrode material by solid-phase sintering method, adds at least three kinds of additives of metal ions, and makes full use of various characteristics of metal ions in additives, Matching various metal ions improves the cycle performance and thermal stability of the material, and comprehensively improves the electrochemical performance of the ultra-high nickel cathode material.

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 undergo acid-base neutralization reaction with the lithium source on the surface of the primary sintering product, thereby reducing the residual alkali content on the surface of the positive electrode material, and the glycine directly interacts with the primary sintered material. Mixed instead of as an additive to water or alcohol washing, the material is acid washed, which avoids the direct erosion of the surface of the positive electrode material by water washing or alcohol washing, and promotes the dissolution of lithium and other metals, resulting in capacity loss, and at the same time avoids water washing or alcohol washing. The destruction of the surface structure, in addition, the addition of glycinate such as aluminum glycinate, aluminum zirconium glycinate, etc. also has a positive effect on the surface coating of the positive electrode material to form a protective coating, and the molten organic acid salt can interact with the residual alkali on the surface of the sintered product (OH-, ^OH- , CO ₃ ^2- ) is reacted and removed, so that the free lithium on the surface is combined with other elements (Al or Zr, etc.) to form a lithium salt compound, and a protective coating is formed on the surface of the positive electrode material, which greatly reduces the residual alkali on the surface of the material. , which can effectively isolate the corrosion of the electrolyte on the inside of the material, inhibit the occurrence of side reactions, have a stable structure, improve thermal stability, reduce impedance, and improve the function of material circulation.

The applicant declares that the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should Changes or substitutions that can be easily conceived within the technical scope all fall within the protection scope and disclosure scope of the present invention.

Claims (10)

1. The preparation method of the ultrahigh nickel ternary cathode material is characterized by comprising the following steps of:

(1) Mixing the ultrahigh nickel ternary precursor, a lithium source and an additive, and sintering to obtain a primary sintered material;

(2) Mixing a primary sintering material and a glycine source, and carrying out heat treatment to obtain the ultra-high nickel ternary positive electrode material;

wherein, the additive in the step (1) comprises any three or at least four of aluminum oxide, magnesium hydroxide, zirconium oxide, yttrium oxide or tungsten oxide.

2. The method of claim 1, wherein the chemical formula of the ultra-high nickel ternary precursor of step (1) is Ni _x Co _y Mn _z (OH) ₂ (ii) a Wherein x + y + z =1, x is more than or equal to 0.95 and less than 1, y is more than or equal to 0.01 and less than or equal to 0.1, and z is more than or equal to 0.01 and less than or equal to 0.1;

preferably, the lithium source comprises lithium hydroxide and/or lithium carbonate;

preferably, the ratio of the molar quantity of the lithium element in the lithium source to the total molar quantity of the metal elements in the ultrahigh nickel ternary precursor is (1.01-1.1): 1.

3. The method according to claim 1 or 2, wherein the additive of step (1) comprises alumina, magnesium hydroxide, zirconia, yttria and tungsten oxide;

preferably, the mass ratio of the magnesium hydroxide to the ultrahigh nickel ternary precursor is (0.1-0.4): 100;

preferably, the mass ratio of the alumina to the ultrahigh nickel ternary precursor is (0.1-0.4): 100;

preferably, the mass ratio of the yttrium oxide to the ultra-high nickel ternary precursor is (0.05-0.3): 100;

preferably, the mass ratio of the zirconia to the ultra-high nickel ternary precursor is (0.05-0.3): 100;

preferably, the mass ratio of the tungsten oxide to the ultra-high nickel ternary precursor is (0.05-0.3): 100.

4. The method according to any one of claims 1 to 3, wherein the sintering treatment in step (1) is carried out at a temperature of 600 to 900 ℃, preferably 650 to 750 ℃;

preferably, the time of the sintering treatment is 8 to 24 hours, preferably 10 to 20 hours.

5. The process according to any one of claims 1 to 4, wherein the glycine source in step (2) comprises glycine and/or a glycine salt;

preferably, the glycinate salt comprises any one of aluminum glycinate, magnesium glycinate or aluminum zirconium glycinate, or a combination of at least two thereof.

6. The process according to any one of claims 1 to 5, wherein the mass ratio of the glycine source to the calcined material in the step (2) is (0.1 to 5): 100, preferably (0.1 to 3): 100.

7. The method according to any one of claims 1 to 6, wherein the temperature of the heat treatment in step (2) is 250 to 600 ℃, preferably 300 to 600 ℃;

preferably, the time of the heat treatment is 6 to 24 hours, preferably 6 to 15 hours.

8. The ultra-high nickel ternary cathode material is prepared by the method of any one of claims 1 to 7, and comprises an inner core and a coating layer arranged on the surface of the inner core, wherein the chemical formula of the inner core is Li _1+y (Ni _a Co _b Mn _1-a-b-c B _c ) _1-y O ₂ Wherein y is more than or equal to 0 and less than or equal to 0.1, a is more than or equal to 0.95 and less than or equal to 1, b is more than or equal to 0.01 and less than or equal to 0.1, c is more than or equal to 0 and less than or equal to 0.05, and B is Mg ²⁺ 、Al ³⁺ 、Zr ⁴⁺ 、Y ³⁺ Or W ⁶⁺ Any one or a combination of at least two of them.

9. A positive electrode sheet comprising the ultra-high nickel ternary positive electrode material of claim 8.

10. A lithium ion battery comprising the positive electrode sheet of claim 9.

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