CN114824196A - High-power long-cycle nickel-cobalt-manganese ternary cathode material and preparation method thereof - Google Patents

High-power long-cycle nickel-cobalt-manganese ternary cathode material and preparation method thereof Download PDF

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CN114824196A
CN114824196A CN202210294792.2A CN202210294792A CN114824196A CN 114824196 A CN114824196 A CN 114824196A CN 202210294792 A CN202210294792 A CN 202210294792A CN 114824196 A CN114824196 A CN 114824196A
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cobalt
precursor
secondary particles
nickel
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赵小康
杨鹏
李艳
刘启明
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BASF Shanshan Battery Materials Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
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    • C—CHEMISTRY; METALLURGY
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    • C01G53/00—Compounds of nickel
    • C01G53/40—Nickelates
    • C01G53/42—Nickelates containing alkali metals, e.g. LiNiO2
    • C01G53/44—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
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    • C01P2004/03—Particle morphology depicted by an image obtained by SEM
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    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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    • C01P2006/40—Electric properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes

Abstract

The invention provides a high-power long-cycle nickel-cobalt-manganese ternary cathode material and a preparation method thereof, wherein the high-power long-cycle nickel-cobalt-manganese ternary cathode material consists of secondary particles, and the appearance of primary particles forming the secondary particles is strip-shaped; the D50 particle diameter of the secondary particles is controlled to be 2.0-5.0 μm and is in an inner hollow structure, and the thickness D of the outer wall of the secondary particles 1 0.3 to 1.1 μm and a wall-to-pore ratio R of the secondary particles of 0.1 to 0.7, wherein R is d 1 /(D50‑2d 1 ). The preparation method comprises the following steps: s1 synthesis of Ni-Co-Mn hydroxide by coprecipitationThe precursor grows on the surface of the loose core and forms a compact shell; s2, mixing the precursor, the lithium salt and the dopant, uniformly mixing and sintering; and S3, crushing and dissociating the sintered product, mixing the crushed and dissociated product with the coating, uniformly mixing the mixture and sintering the mixture. According to the invention, through controlling the wall-hole ratio, the morphology and the primary particle arrangement mode, the processing performance of the material is improved, and meanwhile, the high-power and long-cycle performance can be considered, so that the performance requirements of the HEV type battery are met.

Description

High-power long-cycle nickel-cobalt-manganese ternary cathode material and preparation method thereof
Technical Field
The invention belongs to the technical field of lithium battery anode materials, and particularly relates to a high-power long-cycle nickel-cobalt-manganese ternary anode material and a preparation method thereof.
Background
The HEV hybrid technology is the most effective energy-saving technology of internal combustion engines and automobiles at the present stage, has high requirements on high power and long cycle performance of the anode material of the lithium ion battery due to the application characteristics and performance requirements of the HEV hybrid technology, in order to meet the high power requirement of a lithium ion battery and realize the rapid de-intercalation of lithium ions in a cathode material, the existing material design solution reduces the lithium ion diffusion path by designing a small-particle hollow material, meets the high rate performance of the material, but small particles have larger specific surface area and more surface active sites at the same time, in the using process, the side reaction of the electrolyte is easy to occur, and meanwhile, the hollow material structure has intrinsic defects, compared with a solid material, the structure is easy to collapse in the processing and using processes, the material performance is deteriorated, the service life of the material is influenced, and the power and the cycle performance of the current material cannot be well considered.
Disclosure of Invention
The invention aims to solve the technical problem of overcoming the defects and shortcomings in the background technology and provides a high-power long-cycle nickel-cobalt-manganese ternary cathode material and a preparation method thereof.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
a high-power long-cycle nickel-cobalt-manganese ternary cathode material is composed of secondary particles, and the shapes of primary particles forming the secondary particles are strip-shaped;
the D50 particle size of the secondary particles is controlled to be 2.0-5.0 mu m and is of an inner hollow structure, and the thickness D of the outer wall of the secondary particles 1 0.3 to 1.1 μm and the wall-to-pore ratio R of the secondary particles is0.1 to 0.7, wherein the wall-to-hole ratio R ═ d 1 /(D50-2d 1 )。
Preferably, the primary particles have a crystal grain size of 170 to 180nm and are radially arranged.
Preferably, the D50 particle diameter of the secondary particles is controlled to be 2.8-3.3 mu m, and the thickness D of the outer wall 1 0.3 to 0.7 μm, a wall-to-hole ratio R of 0.11 to 0.50, and a primary particle having a compact plate-like shape and an aspect ratio of 1.67 to 4.12.
Preferably, the grain diameter of the secondary particles D50 is controlled to be 3.8-4.3 μm, and the thickness D of the outer wall 1 0.7 to 1.1 μm, a wall-to-hole ratio R of 0.24 to 0.69, and a primary particle having a compact plate-like shape and an aspect ratio of 3.89 to 6.47.
The two optimized materials have approximate wall-hole ratios, one adopts a hollow structure with a slightly larger grain diameter and a loose and slightly thicker shell, the other adopts a hollow structure with a small grain diameter and a compact and thin shell, and the two materials are comprehensively complementary through the outer wall thickness, the wall-hole ratio and the primary particle shape, so that better high power and long cycle performance are realized.
Preferably, the general formula of the high-power long-cycle nickel-cobalt-manganese ternary cathode material is Li u Ni 1-x-y- z Co x Mn y M z N v O 2-w Wherein u is more than 0.9 and less than 1.2, x is more than 0 and less than 0.3, y is more than 0 and less than 0.3, z is more than or equal to 0 and less than or equal to 0.02, v is more than or equal to 0 and less than or equal to 0.01, w is more than or equal to 0.05 and less than or equal to 0.05, M is a doping element, and N is a cladding element; m is at least one of Al, Mg, Zr, Ti, Y, W, Ta, Nb, Ce, Sn, B and Mo, and N is at least one of Al, Zr, Ti, Y, W, Nb, Ce, Sn, B, Mo and F.
As a general inventive concept, the invention provides a preparation method of the high-power long-cycle nickel-cobalt-manganese ternary positive electrode material, which comprises the following steps:
s1, synthesizing a nickel-cobalt-manganese hydroxide precursor by adopting a coprecipitation method, wherein the synthesis of the precursor comprises a precursor nucleation stage and a precursor growth stage, a loose core is formed in the precursor nucleation stage, and then a compact shell is formed on the surface of the loose core in the precursor growth stage;
s2, mixing the nickel-cobalt-manganese hydroxide precursor synthesized in the step S1, lithium salt and a dopant according to a certain proportion, wherein the dopant is a compound containing one or more elements of Al, Mg, Zr, Ti, Y, W, Ta, Nb, Ce, Sn, B and Mo, and sintering after being uniformly mixed;
and S3, crushing and dissociating the sintered product obtained in the step S2, mixing the crushed product with a coating according to a certain proportion, uniformly mixing the coating and the coating, wherein the coating is a compound containing one or more elements of Al, Zr, Ti, Y, W, Nb, Ce, Sn, B, Mo and F, and sintering the mixture to obtain the high-power long-cycle nickel-cobalt-manganese ternary battery positive electrode material.
Preferably, in the step S1, the temperature of the reaction is controlled to be 50-60 ℃, the pH value is 11.0-12.0, the rotating speed is 400-600 rpm, the ammonia concentration is 7-10 g/L, and the reaction time is 1-3 h; the temperature of the reaction is controlled to be 40-50 ℃, the pH value is 10.0-11.0, the rotating speed is 300-500 rpm, the ammonia concentration is 2-5 g/L, and the reaction time is 10-16 h in the precursor growth stage.
The method comprises the following steps of (1) controlling the process conditions such as temperature, pH value, ammonia concentration, stirring speed and the like of different stages, wherein the nucleation speed is promoted by higher temperature, pH value and ammonia concentration in the nucleation stage, and primary particles are refined by higher stirring speed to form a loose aggregate core; in the growth stage, the pH value, the ammonia concentration and the stirring speed are reduced, no nucleation reaction occurs, primary particles grow in a loose and aggregated mode to form a compact shell, and a hollow small particle precursor with a loose inner core and a thick outer wall is generated.
Preferably, in step S2, the lithium salt is one or two of lithium carbonate, lithium hydroxide, lithium nitrate, lithium fluoride and lithium phosphate. Preferably, the dopant is a compound containing one or more elements of Al, Zr, Y, W, Nb, Ta, Ce and Mo. More preferably, the dopant is a compound containing one or more elements of Zr and Ta.
Preferably, in the step S2, the sintering temperature is 600-900 ℃, and the temperature is kept for 6-20 h.
Preferably, in the step S3, the sintering temperature is 200-900 ℃, and the temperature is kept for 4-10 h.
Compared with the prior art, the invention has the beneficial effects that:
(1) according to the ternary cathode material, the thickness of the outer wall, the wall-hole ratio, the morphology, the primary particle arrangement mode and the like of the material are reasonably controlled by controlling the technological parameters of the nucleation and growth processes of the precursor, and the thin wall thickness and the proper wall-hole ratio can not only shorten the transmission distance of lithium ions, but also promote the infiltration of electrolyte and improve the diffusion rate of the lithium ions. Meanwhile, the surface energy of the 003 plane is reduced by element doping modification and control of process parameters of a precursor, so that primary particles grow along the 003 plane to generate strip-shaped primary particles with smaller grain sizes, the primary particles are radially arranged, the formed crystal structure is stable, the selection of the wall hole ratio can also ensure the stability of the crystal structure, the structure of the undersized wall hole is unstable compared with that of the secondary particle, the electrode is easy to collapse and break in the electrode processing and recycling processes, the recycling performance of the material is influenced, the overlarge wall hole ratio can increase the diffusion path of lithium ions and influence the power performance of the material, namely, the invention improves the processing performance of the material and can also consider high power and long recycling performance by controlling the wall hole ratio, the morphology and the arrangement mode of the primary particles, and the performance requirements of HEV vehicle type batteries are met.
(2) When the ternary cathode material is prepared, the proper doping elements and sintering process are adopted, the size and the shape of primary particles are controlled, and the primary particles are refined, so that higher sintering temperature can be realized, and the requirements of good crystallinity and smaller primary particles at high temperature are met. Wherein, preferably, the Zr element can be combined with co-doping at the temperature of more than 700 ℃ to form a stable crystal structure (Zr-O strong bond) and ZrO 2 React with residual lithium on the surface of the particles to form Li 2 ZrO 3 The high-speed ion conductor improves the diffusion rate of lithium ions, protects the surface of the anode material, and inhibits the side reaction of the surface of the anode material and electrolyte, thereby improving the power and cycle performance of the material.
(3) When the ternary cathode material is prepared, the ternary cathode material is reacted with residual lithium on the surface of the material by adopting a proper surface coating element and a sintering process, so that the residual lithium is reduced, the surface of the material is coated with a thin and uniform ion conductor, an oxygen atom on the surface can be fixed while a lithium ion transmission channel is established, the side reaction between the surface of the material and an electrolyte is inhibited, the high power is ensured, and the cycle performance of the material is improved.
(4) When the ternary cathode material is prepared, the dissociation effect of the secondary particles is controlled through a proper crushing process, the integrity of the secondary particles is ensured while the secondary particles are dissociated, uniform and narrowly distributed particles are formed, the uniformity of the particle size of the particles is improved, a narrower particle range is obtained, and the use uniformity of the material is improved.
(5) According to the invention, by preparing a proper precursor and combining element doping, coating, modifying and sintering processes, the particle size morphology and structure of the ternary cathode material are regulated, the crystal structure and the surface of the material are modified, high power and high cycle life are both considered, and the ternary cathode material has high capacity, stable and safe structure, small internal resistance, high-power and long cycle safety when the battery is used, the safe and high-performance use requirement of a high-power vehicle type is met, and the ternary cathode material is suitable for the requirement of a HEV power type vehicle battery.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is an SEM image of a high power long cycle nickel-cobalt-manganese ternary precursor prepared in example 1;
fig. 2 is a cross-sectional view of the high power long cycle nickel-cobalt-manganese ternary precursor prepared in example 1;
FIG. 3 is an SEM image of a high-power long-cycle nickel-cobalt-manganese ternary cathode material prepared in example 1;
FIG. 4 is a cross-sectional view of the high power long cycle nickel cobalt manganese ternary positive electrode material prepared in example 1;
fig. 5 is an SEM image of the high power long cycle ni — co-mn ternary precursor prepared in example 2;
fig. 6 is a cross-sectional view of the high power long cycle nickel-cobalt-manganese ternary precursor prepared in example 2;
FIG. 7 is an SEM image of a high-power long-cycle nickel-cobalt-manganese ternary cathode material prepared in example 2;
fig. 8 is a cross-sectional view of the high power long cycle ni-co-mn ternary positive electrode material prepared in example 2;
fig. 9 is a graph of cycle performance of nickel-cobalt-manganese ternary cathode materials prepared in examples and comparative examples.
Detailed Description
In order to facilitate understanding of the invention, the invention will be described more fully and in detail with reference to the accompanying drawings and preferred embodiments, but the scope of the invention is not limited to the specific embodiments below.
Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
Example 1:
a high-power long-cycle nickel-cobalt-manganese ternary cathode material with a chemical formula of Li 1.04 Ni 0.592 Co 0.2 Mn 0.2 Zr 0.003 Ta 0.005 O 2 · 0.00075Al 2 O 3 The shape of the primary particles forming the secondary particles is strip-shaped, and the primary particles are arranged in a radial shape. The secondary particles have a D50 particle diameter of 4.0 μm and an inner hollow structure, and an outer wall thickness D 1 0.8 μm, and the secondary particle has a wall-to-pore ratio R of 0.33, wherein R is d 1 /(D50-2d 1 )。
The primary particles had a crystal grain size of 180nm, a compact plate-like shape and an aspect ratio of 4.44. Ratio of ternary cathode materialsSurface area BET of 0.8m 2 /g。
Outer wall thickness d in the embodiments of the invention 1 The average value is obtained by taking a plurality of thicknesses on the wall of the positive electrode material through a section electron microscope image and testing.
The preparation method of the high-power long-cycle nickel-cobalt-manganese ternary cathode material comprises the following steps of:
1) preparation of the precursor
Ni synthesis by coprecipitation method 0.6 Co 0.2 Mn 0.2 (OH) 2 The precursor is prepared by the following specific steps:
taking pure water as a solvent, selecting nickel sulfate, cobalt sulfate and manganese sulfate as raw materials according to Ni 2+ :Co 2+ :Mn 2+ Preparing 2mol/L mixed metal salt solution, and simultaneously preparing 2mol/L NaOH solution and 3mol/L ammonia water solution according to the molar ratio (6: 2: 2); and simultaneously adding the mixed metal salt solution, the NaOH solution and the ammonia water solution into the reaction kettle through a mass flow meter, and controlling the feeding speed of the mixed metal salt solution to be 80 ml/min.
In the precursor nucleation stage, the pH is controlled to be 11.7, the rotating speed is 500rpm, the ammonia concentration is 8g/L, the reaction time is 2h, and the reaction temperature is 55 ℃; the pH value is controlled to be 10.8 in the growth stage, the rotating speed is 400rpm, the ammonia concentration is 5g/L, the reaction time is 14h, and the reaction temperature is 45 ℃.
Reacting until the granularity D50 grows to 4.0 mu m, stopping feeding, filtering, washing and drying to obtain Ni 0.6 Co 0.2 Mn 0.2 (OH) 2 And (3) precursor. SEM images and cross-sectional views of the Ni-Co-Mn ternary precursor are shown in FIGS. 1-2.
2) Preparation of cathode material
Mixing the above Ni 0.6 Co 0.2 Mn 0.2 (OH) 2 Precursor, lithium hydroxide monohydrate, nano-grade ZrO 2 And Ta 2 O 5 According to a molar ratio of 1: 1.08: 0.003: 0.005 is added into a high-speed mixing stirrer, stirred for 30min at the rotating speed of 1800r/min, and then heated to 850 ℃ at the heating rate of 3 ℃/min in a box-type furnace with the oxygen concentration of more than or equal to 96 percent, and the temperature is preserved for 12h to obtain a sintering material;
carrying out primary crushing on the sintered material by using a jaw crusher, then crushing by using a jet mill crusher, controlling the air pressure to be 0.3MPa, controlling the classification frequency to be 45Hz and the induced air frequency to be 40Hz, effectively fully dissociating the sintered agglomerated particles and controlling the particle size, and mixing the crushed material and aluminum oxide according to the molar ratio of 1: 0.0015 of the mixed solution is added into a high-speed mixing stirrer, the mixed solution is stirred for 30min at the rotating speed of 1800r/min, and then the temperature is increased to 350 ℃ at the heating rate of 3 ℃/min in a box-type furnace in the air atmosphere, and the temperature is kept for 6h, so that the ternary cathode material is obtained.
The SEM pictures and the section pictures of the ternary cathode material are shown in figures 3-4, the ternary cathode material is hollow sphere-like, the shell is loose and porous, and therefore lithium ions can be conveniently and rapidly de-embedded, meanwhile, the shell is formed by radially arranging strip-shaped plate-shaped primary particles, the lattice structure of the material is stabilized while the rapid de-embedding of the lithium ions is ensured, the mechanical strength of the material is improved, and the cycle performance of the material is improved.
Example 2:
a high-power long-cycle nickel-cobalt-manganese ternary cathode material with a chemical formula of Li 1.04 Ni 0.592 Co 0.2 Mn 0.2 Zr 0.003 Ta 0.005 O 2 · 0.00075Al 2 O 3 The shape of the primary particles forming the secondary particles is strip-shaped, and the primary particles are arranged in a radial shape. The secondary particles have a D50 particle diameter of 3.0 μm and an inner hollow structure, and an outer wall thickness D 1 0.5 μm, and the secondary particle has a wall-to-pore ratio R of 0.25, wherein R is d 1 /(D50-2d 1 )。
The primary particles had a crystal grain size of 172nm, a compact plate-like shape and an aspect ratio of 2.91. The specific surface area BET of the ternary cathode material is 1.2m 2 /g。
The preparation method of the high-power long-cycle nickel-cobalt-manganese ternary cathode material comprises the following steps of:
1) preparation of the precursor
Ni synthesis by coprecipitation method 0.6 Co 0.2 Mn 0.2 (OH) 2 The precursor is prepared by the following specific steps:
taking pure water as a solvent, selecting nickel sulfate, cobalt sulfate and manganese sulfate as raw materials according to Ni 2+ :Co 2+ :Mn 2+ Preparing 2mol/L mixed metal salt solution, and simultaneously preparing 2mol/L NaOH solution and 3mol/L ammonia water solution according to the molar ratio (6: 2: 2); and simultaneously adding the mixed metal salt solution, the NaOH solution and the ammonia water solution into the reaction kettle through a mass flow meter, and controlling the feeding speed of the mixed metal salt solution to be 80 ml/min.
In the precursor nucleation stage, the pH is controlled to be 11.7, the rotating speed is 500rpm, the ammonia concentration is 8g/L, the reaction time is 2h, and the reaction temperature is 55 ℃; the pH value is controlled to be 10.3 in the growth stage, the rotating speed is 350rpm, the ammonia concentration is 3g/L, the reaction time is 14h, and the reaction temperature is 45 ℃.
Reacting until the granularity D50 grows to 3.0 mu m, stopping feeding, filtering, washing and drying to obtain Ni 0.6 Co 0.2 Mn 0.2 (OH) 2 And (3) precursor. SEM images and cross-sectional views of the Ni-Co-Mn ternary precursor are shown in FIGS. 5-6.
2) Preparation of cathode material
Mixing the above Ni 0.6 Co 0.2 Mn 0.2 (OH) 2 Precursor, lithium hydroxide monohydrate, nano-grade ZrO 2 And Ta 2 O 5 According to a molar ratio of 1: 1.08: 0.003: 0.005 is added into a high-speed mixing stirrer, stirred for 30min at the rotating speed of 1800r/min, and then heated to 850 ℃ at the heating rate of 3 ℃/min in a box-type furnace with the oxygen concentration of more than or equal to 96 percent, and the temperature is preserved for 12h to obtain a sintering material;
carrying out primary crushing on the sintered material by using a jaw crusher, then crushing by using a jet mill crusher, controlling the air pressure to be 0.3MPa, controlling the classification frequency to be 45Hz and the induced air frequency to be 40Hz, effectively fully dissociating the sintered agglomerated particles and controlling the particle size, and mixing the crushed material and aluminum oxide according to the molar ratio of 1: 0.0015 of the mixed solution is added into a high-speed mixing stirrer, the mixed solution is stirred for 30min at the rotating speed of 1800r/min, and then the temperature is increased to 350 ℃ at the heating rate of 3 ℃/min in a box-type furnace in the air atmosphere, and the temperature is kept for 6h, so that the ternary cathode material is obtained.
The SEM pictures and the section pictures of the ternary cathode material are shown in figures 7-8, the ternary cathode material is in a hollow sphere-like shape, the shell is formed by radially arranging strip-shaped plate-shaped primary particles, the shell is thin and compact, and has few holes, so that the rapid lithium ion extraction is ensured, the lattice structure of the material is stabilized, the mechanical strength of the material is improved, and the cycle performance of the material is improved.
Comparative example 1:
the lithium ion battery anode material is a solid small-particle secondary sphere NCM622 ternary anode material, and the D50 particle size of secondary particles is 4.5 mu m. The specific surface area BET of the positive electrode material was 0.6m 2 The shape is similar to spherical secondary particles. The grain size of the primary particles constituting the secondary particles was 196 nm.
The preparation method of the ternary cathode material comprises the following steps:
1) preparation of the precursor
Ni synthesis by coprecipitation method 0.6 Co 0.2 Mn 0.2 (OH) 2 The precursor is prepared by the following specific steps:
taking pure water as a solvent, selecting nickel sulfate, cobalt sulfate and manganese sulfate as raw materials according to Ni 2+ :Co 2+ :Mn 2+ Preparing 2mol/L mixed metal salt solution, and simultaneously preparing 2mol/L NaOH solution and 3mol/L ammonia water solution according to the molar ratio (6: 2: 2); simultaneously adding a mixed metal salt solution, a NaOH solution and an ammonia water solution into a reaction kettle through a mass flow meter, controlling the feeding speed of the mixed metal salt solution to be 120ml/min, controlling the reaction temperature to be 50 ℃, the pH to be 11.0, the rotating speed to be 300rpm and the ammonia concentration to be 6g/L, stopping feeding after the mixed metal salt solution reacts until the granularity D50 grows to 4.5 mu m, filtering, washing and drying to obtain Ni 0.6 Co 0.2 Mn 0.2 (OH) 2 And (3) precursor.
2) Preparation of cathode material
Mixing the above Ni 0.6 Co 0.2 Mn 0.2 (OH) 2 Precursor, lithium hydroxide monohydrate, nano-grade ZrO 2 And Ta 2 O 5 According to a molar ratio of 1: 1.08: 0.003: 0.005 adding into a high-speed mixer, stirring at 1800r/min for 30min, and then adding oxygenHeating to 850 ℃ at a heating rate of 3 ℃/min in a box furnace with the concentration of more than or equal to 96 percent, and keeping the temperature for 12 hours to obtain a sintering material;
carrying out primary crushing on the sintered material by using a jaw crusher, then crushing by using a jet mill crusher, controlling the air pressure to be 0.3MPa, controlling the classification frequency to be 45Hz and the induced air frequency to be 40Hz, effectively fully dissociating the sintered agglomerated particles and controlling the particle size, and mixing the crushed material and aluminum oxide according to the molar ratio of 1: 0.0015, adding the mixture into a high-speed mixing stirrer, stirring the mixture for 30min at the rotating speed of 1800r/min, and then heating the mixture to 350 ℃ at the heating speed of 3 ℃/min in a box-type furnace in the air atmosphere, and preserving the heat for 6h to obtain the ternary material for the lithium ion battery.
Comparative example 2:
the lithium ion battery anode material is a hollow small-particle secondary sphere NCM622 ternary anode material, and the D50 particle size of secondary particles is 3.9 mu m. Outer wall thickness d of secondary particles 1 0.8 μm, and a wall-to-pore ratio R of the secondary particles of 0.35, wherein R is d 1 /(D50-2d 1 ). The primary particles had a crystal grain size of 188nm and an aspect ratio of 4.26. The specific surface area BET of the ternary cathode material is 1.1m 2 The shape is hollow sphere-like.
The preparation method of the ternary cathode material comprises the following steps:
1) preparation of the precursor
Ni synthesis by coprecipitation method 0.6 Co 0.2 Mn 0.2 (OH) 2 The precursor is prepared by the following specific steps:
taking pure water as a solvent, selecting nickel sulfate, cobalt sulfate and manganese sulfate as raw materials according to Ni 2+ :Co 2+ :Mn 2+ Preparing 2mol/L mixed metal salt solution, and simultaneously preparing 2mol/L NaOH solution and 3mol/L ammonia water solution according to the molar ratio (6: 2: 2); and simultaneously adding the mixed metal salt solution, the NaOH solution and the ammonia water solution into the reaction kettle through a mass flow meter, and controlling the feeding speed of the mixed metal salt solution to be 80 ml/min.
In the precursor nucleation stage, the pH is controlled to be 11.7, the rotating speed is 500rpm, the ammonia concentration is 8g/L, the reaction time is 2h, and the reaction temperature is 55 ℃; the pH value is controlled to be 10.8 in the growth stage, the rotating speed is 400rpm, the ammonia concentration is 5g/L, the reaction time is 14h, and the reaction temperature is 45 ℃.
Reacting until the granularity D50 grows to 4.0 mu m, stopping feeding, filtering, washing and drying to obtain Ni 0.6 Co 0.2 Mn 0.2 (OH) 2 And (3) precursor.
2) Preparation of cathode material
Mixing the above Ni 0.6 Co 0.2 Mn 0.2 (OH) 2 The precursor and the lithium hydroxide monohydrate are mixed according to a molar ratio of 1: 1.08 adding the mixture into a high-speed mixing stirrer, stirring for 30min at the rotating speed of 1800r/min, heating to 850 ℃ at the heating speed of 3 ℃/min in a box-type furnace with the oxygen concentration of more than or equal to 96%, preserving heat for 12h, primarily crushing the sintered material by using a jaw crusher, crushing by using a jet mill crusher, controlling the air pressure to be 0.3MPa, the classification frequency to be 45Hz and the induced air frequency to be 40Hz, and effectively fully dissociating the sintered agglomerated particles and controlling the particle size to obtain the ternary material for the lithium ion battery.
And (3) performance testing:
the electrochemical performance of the positive electrode materials in the above examples and comparative examples was investigated using a soft pack battery model 3030C 0.
Positive pole piece: the positive electrode materials of examples 1 and 2 and comparative examples 1 and 2, conductive carbon black (SP), conductive graphite (KS-6), and polyvinylidene fluoride (PVDF) were mixed in a ratio of 92: 3: 3: and 2, stirring and dispersing the mixture with a solvent NMP, coating the mixture on an aluminum foil substrate, and rolling to obtain the positive pole piece.
Negative pole piece: graphite, SP, CMC and SBR are mixed according to the weight ratio of 95.2: 1: 1.5: and 2.3, stirring and dispersing the mixture with water, coating the mixture on a copper foil substrate, and rolling to obtain the negative pole piece.
Electrolyte solution: 1mol/L LiPF6 solution, wherein the solvent is a mixed solvent of EC and DMC, and the ratio of the EC to the DMC is 1: 2, the additive is 1% of VC.
And winding the positive plate, the negative plate and the diaphragm into a battery pole core, assembling by adopting an aluminum plastic film shell, encapsulating and assembling into a 0.35Ah soft package battery after injecting electrolyte, and performing battery test, wherein the charge cut-off voltage is 4.2V, and the discharge cut-off voltage is 2.75V.
The following are results of testing electrical properties of the positive electrode materials prepared in examples 1-2 and comparative examples 1-2. The results of the electrical properties are shown in table 1, and fig. 9 is a graph showing cycle properties of the positive electrode materials prepared in examples and comparative examples.
Table 1 electrical property test results of the positive electrode material
Group of Capacity (mAh/g) Multiplying factor (%) DCR(mΩ) Normal temperature cycle (%)
Example 1 173.0 70.3 92.3 2000cls/81.35％
Example 2 172.7 66.9 93.5 2000cls/80.67％
Comparative example 1 173.3 64.1 102.0 1471cls/80.00％
Comparative example 2 172.1 59.8 95.6 1248cls/80.11％
As can be seen from table 1, the positive electrode material in example 1 has a slightly thick and loose shell, and the crystal structure and the surface of the material are modified by a hollow structure with a slightly large particle size, a slightly thick and loose shell and doping coating modification, so that high power and long cycle performance are realized, and the rate performance, DCR performance and cycle performance of example 1 are optimal, thereby meeting the requirements of high power and long cycle performance of HEV (electric vehicle) type batteries.
The positive electrode material in the embodiment 2 has a compact and thin shell, the crystal structure and the surface of the material are modified through a small-particle-size, compact and thin shell hollow structure and doping coating modification, high-power and long-cycle performance is realized, the multiplying power performance, the DCR performance and the cycle performance of the embodiment 2 are excellent, and the requirements of high-power and long-cycle performance of batteries of HEV (electric vehicle) types are met.
The cathode material in comparative example 1 has the highest DCR and poor cycle performance, and cannot meet the requirements of high power and long cycle performance of batteries of HEV models.
The anode material in the comparative example 2 is not subjected to doping coating modification, has poor multiplying power and cycle performance, and cannot meet the requirements of high power and long cycle performance of batteries of HEV (electric vehicle) types.
According to the embodiment of the invention, the particle size morphology and structure of the material are regulated and controlled through a proper precursor and element doping coating modification and sintering process, the crystal structure and the surface of the material are modified, and the material prepared by the embodiment has excellent physical and chemical properties and electrical properties, ensures the processing performance of the material, gives consideration to high power and long cycle performance, and meets the performance requirements of the HEV type battery.

Claims (10)

1. The high-power long-cycle nickel-cobalt-manganese ternary cathode material is characterized in that: the high-power long-cycle nickel-cobalt-manganese ternary cathode material consists of secondary particles, and the appearance of primary particles forming the secondary particles is strip-shaped;
the D50 particle size of the secondary particles is controlled to be 2.0-5.0 mu m and is of an inner hollow structure, and the thickness D of the outer wall of the secondary particles 1 0.3 to 1.1 μm and a wall-to-pore ratio R of the secondary particles of 0.1 to 0.7, wherein R is d 1 /(D50-2d 1 )。
2. The high power long cycle nickel cobalt manganese ternary positive electrode material of claim 1, wherein: the grain size of the primary particles is 170-180 nm, and the primary particles are radially arranged.
3. The high power long cycle nickel cobalt manganese ternary positive electrode material of claim 1 or 2, characterized in that: the D50 particle size of the secondary particles is controlled to be 2.8-3.3 mu m, and the thickness D of the outer wall 1 0.3 to 0.7 μm, a wall-to-hole ratio R of 0.11 to 0.50, and a primary particle having a compact plate-like shape and an aspect ratio of 1.67 to 4.12.
4. The high power long cycle nickel cobalt manganese ternary positive electrode material of claim 1 or 2, characterized in that: the grain diameter of the secondary particles D50 is controlled to be 3.8-4.3 mu m, and the thickness D of the outer wall 1 0.7 to 1.1 μm, a wall-to-pore ratio R of 0.24 to 0.69, and a ratio of length to diameter of the primary particles of 3.89 to 6.47.
5. The high power long cycle nickel cobalt manganese ternary positive electrode material of claim 1 or 2, characterized in that: the general formula of the high-power long-cycle nickel-cobalt-manganese ternary cathode material is Li u Ni 1-x-y-z Co x Mn y M z N v O 2-w Wherein u is more than 0.9 and less than 1.2, x is more than 0 and less than 0.3, y is more than 0 and less than 0.3, z is more than or equal to 0 and less than or equal to 0.02, v is more than or equal to 0 and less than or equal to 0.01, w is more than or equal to 0.05 and less than or equal to 0.05, M isDoping elements, wherein N is a coating element; m is at least one of Al, Mg, Zr, Ti, Y, W, Ta, Nb, Ce, Sn, B and Mo, and N is at least one of Al, Zr, Ti, Y, W, Nb, Ce, Sn, B, Mo and F.
6. The preparation method of the high-power long-cycle nickel-cobalt-manganese ternary cathode material as claimed in any one of claims 1 to 5, wherein the preparation method comprises the following steps: the method comprises the following steps:
s1, synthesizing a nickel-cobalt-manganese hydroxide precursor by adopting a coprecipitation method, wherein the synthesis of the precursor comprises a precursor nucleation stage and a precursor growth stage, a loose core is formed in the precursor nucleation stage, and then a compact shell is formed on the surface of the loose core in the precursor growth stage;
s2, mixing the nickel-cobalt-manganese hydroxide precursor synthesized in the step S1, lithium salt and a dopant according to a certain proportion, wherein the dopant is a compound containing one or more elements of Al, Mg, Zr, Ti, Y, W, Ta, Nb, Ce, Sn, B and Mo, and sintering after being uniformly mixed;
and S3, crushing and dissociating the sintered product obtained in the step S2, mixing the crushed product with a coating according to a certain proportion, uniformly mixing the coating which is a compound containing one or more elements of Al, Zr, Ti, Y, W, Nb, Ce, Sn, B, Mo and F, and sintering to obtain the high-power long-cycle nickel-cobalt-manganese ternary battery positive electrode material.
7. The method of claim 6, wherein: in the step S1, the temperature of the reaction is controlled to be 50-60 ℃, the pH value is 11.0-12.0, the rotating speed is 400-600 rpm, the ammonia concentration is 7-10 g/L, and the reaction time is 1-3 h in the precursor nucleation stage; the temperature of the reaction is controlled to be 40-50 ℃, the pH value is 10.0-11.0, the rotating speed is 300-500 rpm, the ammonia concentration is 2-5 g/L, and the reaction time is 10-16 h in the precursor growth stage.
8. The method of claim 6, wherein: in step S2, the lithium salt is one or two of lithium carbonate, lithium hydroxide, lithium nitrate, lithium fluoride, and lithium phosphate.
9. The method of claim 6, wherein: in step S2, the sintering temperature is 600-900 ℃, and the temperature is kept for 6-20 h.
10. The method of claim 6, wherein: in step S3, the sintering temperature is 200-900 ℃, and the temperature is kept for 4-10 h.
CN202210294792.2A 2022-03-23 2022-03-23 High-power long-cycle nickel-cobalt-manganese ternary cathode material and preparation method thereof Pending CN114824196A (en)

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