CN115386947B - Preparation method of monocrystal ternary positive electrode material - Google Patents
Preparation method of monocrystal ternary positive electrode material Download PDFInfo
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- 238000002360 preparation method Methods 0.000 title claims abstract description 32
- 239000007774 positive electrode material Substances 0.000 title abstract description 22
- 239000000463 material Substances 0.000 claims abstract description 99
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 82
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 42
- 238000002156 mixing Methods 0.000 claims abstract description 34
- 239000000203 mixture Substances 0.000 claims abstract description 31
- 238000000137 annealing Methods 0.000 claims abstract description 28
- 238000000227 grinding Methods 0.000 claims abstract description 18
- 238000001035 drying Methods 0.000 claims abstract description 17
- 239000011572 manganese Substances 0.000 claims abstract description 14
- 238000001354 calcination Methods 0.000 claims abstract description 12
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000002243 precursor Substances 0.000 claims abstract description 11
- 239000010405 anode material Substances 0.000 claims abstract description 7
- SEVNKUSLDMZOTL-UHFFFAOYSA-H cobalt(2+);manganese(2+);nickel(2+);hexahydroxide Chemical compound [OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[Mn+2].[Co+2].[Ni+2] SEVNKUSLDMZOTL-UHFFFAOYSA-H 0.000 claims abstract description 5
- 238000005406 washing Methods 0.000 claims abstract description 5
- 229910017698 Ni 1-x-y Co Inorganic materials 0.000 claims abstract description 3
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical group [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 38
- 238000000034 method Methods 0.000 claims description 28
- YNQRWVCLAIUHHI-UHFFFAOYSA-L dilithium;oxalate Chemical compound [Li+].[Li+].[O-]C(=O)C([O-])=O YNQRWVCLAIUHHI-UHFFFAOYSA-L 0.000 claims description 15
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 7
- RSNHXDVSISOZOB-UHFFFAOYSA-N lithium nickel Chemical compound [Li].[Ni] RSNHXDVSISOZOB-UHFFFAOYSA-N 0.000 abstract description 25
- 230000014759 maintenance of location Effects 0.000 abstract description 22
- 230000002195 synergetic effect Effects 0.000 abstract description 7
- 150000001450 anions Chemical class 0.000 abstract description 5
- 150000001768 cations Chemical class 0.000 abstract description 5
- 239000010406 cathode material Substances 0.000 description 76
- 239000013078 crystal Substances 0.000 description 53
- 239000004570 mortar (masonry) Substances 0.000 description 44
- 229910052573 porcelain Inorganic materials 0.000 description 31
- 238000000967 suction filtration Methods 0.000 description 30
- 239000002245 particle Substances 0.000 description 27
- 230000000052 comparative effect Effects 0.000 description 23
- 238000012360 testing method Methods 0.000 description 21
- 229910052593 corundum Inorganic materials 0.000 description 17
- 239000010431 corundum Substances 0.000 description 17
- 239000012467 final product Substances 0.000 description 16
- 238000011068 loading method Methods 0.000 description 16
- 239000008367 deionised water Substances 0.000 description 15
- 229910021641 deionized water Inorganic materials 0.000 description 15
- 239000000047 product Substances 0.000 description 15
- 238000010298 pulverizing process Methods 0.000 description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 15
- 230000004907 flux Effects 0.000 description 14
- 238000006243 chemical reaction Methods 0.000 description 9
- 239000012071 phase Substances 0.000 description 9
- 238000002844 melting Methods 0.000 description 8
- 230000008018 melting Effects 0.000 description 8
- 229910002991 LiNi0.5Co0.2Mn0.3O2 Inorganic materials 0.000 description 7
- 229910016739 Ni0.5Co0.2Mn0.3(OH)2 Inorganic materials 0.000 description 7
- 229910018068 Li 2 O Inorganic materials 0.000 description 6
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 6
- 229910001416 lithium ion Inorganic materials 0.000 description 6
- 229910011328 LiNi0.6Co0.2Mn0.2O2 Inorganic materials 0.000 description 5
- 230000007547 defect Effects 0.000 description 5
- 239000000376 reactant Substances 0.000 description 5
- 229910013716 LiNi Inorganic materials 0.000 description 4
- 229910017071 Ni0.6Co0.2Mn0.2(OH)2 Inorganic materials 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 230000001788 irregular Effects 0.000 description 3
- 230000000877 morphologic effect Effects 0.000 description 3
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- 235000002639 sodium chloride Nutrition 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 229910001428 transition metal ion Inorganic materials 0.000 description 2
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 1
- 238000003917 TEM image Methods 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- ZYKTVIDNXTWTNS-UHFFFAOYSA-L [Co].[Mn].[Ni](O)O Chemical compound [Co].[Mn].[Ni](O)O ZYKTVIDNXTWTNS-UHFFFAOYSA-L 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
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- 239000011230 binding agent Substances 0.000 description 1
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B9/00—Single-crystal growth from melt solutions using molten solvents
- C30B9/04—Single-crystal growth from melt solutions using molten solvents by cooling of the solution
- C30B9/08—Single-crystal growth from melt solutions using molten solvents by cooling of the solution using other solvents
- C30B9/12—Salt solvents, e.g. flux growth
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/16—Oxides
- C30B29/22—Complex oxides
-
- 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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention discloses a preparation method of a monocrystal ternary anode material, which comprises the following steps: (1) Nickel cobalt manganese hydroxide precursor Ni 1‑x‑y Co x Mn y (OH) 2 Mixing with a lithium source to obtain a mixed material A; (2) Mixing the mixed material A obtained in the step (1) with a fluxing agent to obtain a mixed material B; the fluxing agent is Li 2 CO 3 With Li 2 SO 4 Is a mixture of (a) and (b); (3) And (3) calcining the mixed material B obtained in the step (2), and then crushing, grinding, washing, drying and annealing to obtain the monocrystal ternary anode material. The preparation method adopts Li 2 CO 3 With Li 2 SO 4 The formed fluxing agent promotes the product to grow into a monocrystal ternary positive electrode material with excellent appearance, high crystallinity, low lithium nickel mixed discharge, high specific capacity and high capacity retention rate by the synergistic effect of anions and cations dissociated at high temperature.
Description
Technical Field
The invention belongs to the field of battery materials, and particularly relates to a preparation method of a ternary positive electrode material.
Background
Lithium ion batteries have been widely used in new energy automobiles, consumer electronics, etc., and are one of the most important energy storage devices at present. In the aspect of new energy automobiles, key performances such as energy density, safety and the like of lithium ion power batteries are the focus of continuous attention, and positive electrode materials determine the key performances to a large extent. Among various positive electrode materials, the ternary positive electrode material has the advantages of adjustable components, higher energy density, larger specific capacity and the like, and becomes a main positive electrode material of the lithium ion power battery. However, the current industrialized ternary positive electrode material still has problems in terms of cycle performance and safety performance due to the influence of process and technical factors, and the main reasons are that the currently applied ternary positive electrode material is mostly a polycrystalline ternary positive electrode material, namely, material particles are polycrystalline particles composed of a large number of small crystals, and in the cycle process, uneven expansion and shrinkage of the inside of the particles of the polycrystalline ternary positive electrode material can occur, so that the particles are broken, the cycle performance is poor, side reactions are increased, gas yield is increased, and further the problems of transition metal ion dissolution, reversible capacity reduction and the like are caused. The above problems can greatly reduce the safety of the lithium ion battery, even cause the problems of short circuit, expansion, fire and the like, thereby causing the overheating, out of control and even explosion of the battery.
Based on this, a single crystal ternary cathode material has been developed in order to improve the safety, stability and cycle performance of the battery. The single crystal ternary material is a single-particle crystal ternary positive electrode material, and the single particle is a crystal, and no grain boundary exists in the single particle. Compared with the polycrystalline ternary cathode material, the monocrystalline ternary cathode material cannot generate larger volume strain in multiple cycles, cannot crack and break obviously, effectively improves the cycle performance of the material, inhibits the side reaction of the material, reduces the gas yield of the material, avoids the problems of dissolution of transition metal ions, reduction of reversible capacity and the like, and improves the safety of the lithium ion battery.
However, the current preparation method of the single crystal ternary cathode material is not mature, and the single crystal ternary cathode material with good morphology and crystallinity is difficult to produce by the existing technical means. The preparation method of the single crystal ternary cathode material mainly comprises the following two methods, namely a preparation method for preparing the single crystal ternary cathode material without a fluxing agent. The method prepares the monocrystal ternary anode material by synthesizing a special precursor material, mixing with a lithium source and calcining, and has the defects that: (1) in the aspect of the preparation method, the synthesis of the special precursor material needs more complex process parameter control, and the preparation difficulty is increased; (2) in the aspect of preparing the obtained material, the crystallinity of the material is low, the shape is round and blunt, the phase difference with single crystals is more, even the prepared material is not a single crystal material, and in addition, the lithium nickel mixed discharge is relatively higher. For example, the single crystal ternary cathode material is prepared by a fluxless method according to patent CN110718688A, and has a relatively blunt and irregular shape and relatively low crystallinity. And secondly, preparing the monocrystal ternary cathode material by using a fluxing agent. The method prepares the monocrystal ternary anode material by adding a fluxing agent, and has the defects that: (1) in terms of preparation method, the existing fluxing agent has a higher melting point required for melting, and can not sufficiently melt and wrap reactants at a slightly lower reaction temperature; (2) in the aspect of preparing the obtained material, the shape of the material is poor, the geometric shape is broken, and the crystal face development is imperfect. Due to the defects of the preparation method, the ternary positive electrode material has the problems of low specific capacity, poor capacity retention and the like in the aspect of electrochemical performance.
Therefore, development of a method for preparing a single crystal ternary cathode material without a special precursor is needed to prepare the single crystal ternary cathode material with excellent morphology, high crystallinity, low lithium nickel mixed discharge, high specific capacity and high capacity retention rate.
Disclosure of Invention
The invention aims to solve the technical problems and overcome the defects and shortcomings in the background art, and provides a preparation method of a monocrystal ternary anode material with excellent morphology, high crystallinity, low lithium nickel mixed discharge, high specific capacity and high capacity retention rate. In order to solve the technical problems, the technical scheme provided by the invention is as follows:
a preparation method of a monocrystal ternary positive electrode material comprises the following steps:
(1) Nickel cobalt manganese hydroxide precursor Ni 1-x-y Co x Mn y (OH) 2 Mixing with a lithium source to obtain a mixed material A;
(2) Mixing the mixed material A obtained in the step (1) with a fluxing agent to obtain a mixed material B; the fluxing agent is Li 2 CO 3 With Li 2 SO 4 Is a mixture of (a) and (b);
(3) And (3) calcining the mixed material B obtained in the step (2), and then crushing, grinding, washing (removing fluxing agent), drying and annealing to obtain the monocrystal ternary cathode material.
In the above preparation method, preferably, the flux is Li 2 CO 3 With Li 2 SO 4 The mass ratio is 1: (8.0-10.0).
In the above preparation method, preferably, the flux further contains lithium oxalate, wherein the Li 2 CO 3 The mass ratio of the lithium oxalate to the lithium oxalate is 1: (0.2-0.5).
In the present invention, li is used 2 CO 3 With Li 2 SO 4 When used as a two-component fluxing agent, the two-component fluxing agent is capable of serving two functions: on one hand, the fluxing agent can wrap the reactant by liquid phase after being melted, so that the liquid phase mass transfer is promoted, and the reaction is fully carried out; on the other hand, anions and cations dissociated at high temperature of the fluxing agent can play a synergistic effect to promote ordered growth of crystal faces, so that the prepared monocrystal ternary positive electrode material has high crystallinity and low lithium nickel mixed discharge degree. Control of Li 2 CO 3 With Li 2 SO 4 The mass ratio is 1: (8.0-10.0), the melting temperature of the two-component flux will be lower than Li 2 CO 3 Is higher than Li 2 CO 3 The single component flux is capable of more fully melting and encapsulating the reactants. More preferably, the fluxing agent also comprises Li 2 CO 3 、Li 2 SO 4 Lithium oxalate, lithium oxalate and Li which exert synergistic effect 2 CO 3 、Li 2 SO 4 The synergistic effect can further reduce the melting point of the multicomponent fluxing agent, promote the fluxing agent to melt more quickly, enable the fluxing agent to melt more fully and wrap reactants, promote the reaction at the initial stage of the generation of product particles (at lower temperature), reduce the defects of crystal nucleus or structural template generated at the initial stage of the reaction, enable the crystal grown subsequently to have better crystal morphology, and finally be beneficial to obtaining the monocrystal ternary cathode material with better crystal form. However, the amount of lithium oxalate needs to be reasonably controlled, and the addition of the lithium oxalate is too small, which is unfavorable for the combination of the lithium oxalate and the lithium oxalateLi 2 CO 3 、Li 2 SO 4 The synergistic effect of the (C) is poor, the melting point reducing effect is poor, too much CO is added, otherwise, too much CO generated at high temperature can rob oxygen in the reaction process, and the reaction is incomplete.
In the above preparation method, preferably, the lithium source is LiOH, and the nickel cobalt manganese hydroxide precursor Ni is controlled 1-x- y Co x Mn y (OH) 2 The molar ratio to the lithium source is 1: (1.05-1.10). The lithium source is LiOH, which will preferentially react with the cobalt nickel hydroxide manganese precursor during heating.
In the above preparation method, preferably, the mass ratio of the mixture a to the fluxing agent is 1: (1.2-1.3). When the addition amount of the fluxing agent is too low, the reactant cannot be completely wrapped by the molten fluxing agent, so that a growing environment is difficult to provide for the monocrystal ternary cathode material, and anions and cations dissociated from the fluxing agent cannot well promote the generation of the monocrystal ternary cathode material; when the addition amount of the fluxing agent is too high, the fluxing agent is too much and is not easy to remove by washing, so that the performance of the product is affected.
In the preparation method, preferably, the calcination temperature is controlled to be 900-1000 ℃ and the calcination time is controlled to be 10-14h during the calcination treatment. Our studies have shown that in terms of calcination temperature control, it is desirable for the fluxing agent of the present invention to give a product with a better morphology, requiring matching of the two temperature windows: firstly, a window in which the fluxing agent can stably play a role (namely ensuring that a product has better morphology and phase parameters); the other is a window where the product has stable properties (i.e. ensures that the product has better electrochemical properties). In terms of flux, we have shown that flux may melt at temperatures of 800 ℃ or even lower, but flux forms single crystal structures from materials only in the 900 ℃ to 1100 ℃ range, and has good morphology and phase parameters. In terms of products, the calcined material has better electrochemical performance at about 800 ℃, but when the temperature exceeds 1000 ℃, the product particles are easy to crack, the lithium nickel mixing degree is increased, and the electrochemical performance can be seriously attenuated. Thus 800-1000 ℃ is a temperature window where the product properties are stable. After comprehensive consideration, the calcination temperature is controlled to 900-1000 ℃ based on the consideration that both can stably play a role, and is properly selected.
In the preparation method, preferably, the annealing temperature is controlled to be 500-650 ℃ and the annealing time is controlled to be 4-6h during the annealing treatment. Since the washing process will cause deterioration of the surface structure of the resulting product, it is necessary to anneal the washed product to restore the surface structure thereof. When the temperature is too high, the morphology of the product is easy to degrade, the lithium nickel mixing degree is increased, and the electrochemical performance of the product is reduced; when the temperature is too low, surface rearrangement is imperfect, and it is difficult to recover the performance. Under the annealing temperature and the annealing time length, the surface structure of the monocrystal ternary cathode material is rearranged, and the electrochemical performance of the washed material is improved.
The invention discloses a method for preparing a monocrystal ternary cathode material based on a fluxing agent, wherein anions and cations dissociated from the multicomponent fluxing agent at high temperature can play a synergistic effect to promote ordered growth of crystal faces, so that the prepared monocrystal ternary cathode material has good performance, and the prepared monocrystal ternary cathode material has the main advantages of high crystallinity, low lithium-nickel mixed emission, excellent morphology, close geometrical appearance to an octahedron, perfect development of the crystal faces and the like. In addition, the invention promotes the multi-component fluxing agent to fully play a role through the control of the mass ratio of materials, the calcination parameters, the annealing parameters and the like in a specific range, and has the main advantages of high fluxing agent melting degree, complete removal after reaction and the like.
Compared with the prior art, the invention has the advantages that:
1. the preparation method adopts Li 2 CO 3 With Li 2 SO 4 The formed fluxing agent can fully carry out the reaction, and the product is promoted to grow into a monocrystal ternary positive electrode material with excellent appearance, high crystallinity, low lithium-nickel mixed discharge, high specific capacity and high capacity retention rate by the synergistic effect of anions and cations dissociated at high temperature, the obtained material has good monocrystal appearance, the 50 th cycle specific capacity of (003) and (104) diffraction peak intensity ratio can reach 170.5-185.1mAh/g under 1.87-2.23,1.0C, the 150 th cycle still has high specific capacity of 159.1-183.7mAh/g under 0.5C, the capacity retention rate can reach more than 90 percent, and the highest possibility is achievedUp to 98.2%.
2. Compared with the preparation method for preparing the monocrystal ternary cathode material by using the fluxing agent without the fluxing agent and preparing the monocrystal ternary cathode material by using the monocomponent fluxing agent, the preparation method provided by the invention has the advantages that special precursors are not required to be prepared by complex technological parameters, the fluxing agent melting degree is high, the reaction can be completely removed, and the like.
3. The preparation method has the main advantages of convenient preparation, easy operation, small environmental pollution and the like, and has wide market application prospect.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a process flow diagram of the preparation method of the present invention.
Fig. 2 is an SEM image of the single crystal ternary cathode material prepared in example 1.
Fig. 3 is a TEM image of the single crystal ternary cathode material prepared in example 2.
Fig. 4 is an XRD pattern of the single crystal ternary cathode material prepared in example 3.
Fig. 5 is a graph of capacity versus efficiency for the first 150 cycles of the single crystal ternary cathode material assembled button cell prepared in example 4 at 0.5C rate.
Fig. 6 is a capacity-voltage plot for the 50 th cycle of the single crystal ternary cathode material assembled button cell prepared in example 5 at a 1.0C rate.
Detailed Description
The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments are shown, for the purpose of illustrating the invention, but the scope of the invention is not limited to the specific embodiments shown.
Unless defined otherwise, all technical and scientific terms 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 be limiting of the scope of the present invention.
Unless otherwise specifically indicated, the various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or may be prepared by existing methods.
Example 1:
as shown in fig. 1, a method for preparing a single crystal ternary cathode material based on a two-component flux comprises the following steps:
single crystal ternary cathode material LiNi 0.55 Co 0.15 Mn 0.3 O 2 Is prepared from the following steps: 4.58g Ni 0.55 Co 0.15 Mn 0.3 (OH) 2 And (3) placing 1.32g of LiOH in a mortar for mixing to obtain a precursor-lithium source mixed material. Another 1.00g Li 2 CO 3 With 8.00g Li 2 SO 4 Mixing in another mortar to obtain the double-component fluxing agent. 7.13g of the bi-component fluxing agent is taken and added into the precursor-lithium source mixed material, and the mixture is fully ground and uniformly mixed. The resulting material was charged into a corundum porcelain boat and calcined in a muffle furnace at 900 c for 10 hours. The calcined material was placed in a mortar for pulverization and grinding, transferred to a beaker, washed with magnetic stirring by adding 58.01g of deionized water for 1min, and then poured into a sand core funnel filled with filter paper for suction filtration. And (3) placing the material subjected to suction filtration into a vacuum oven, drying at 120 ℃ for 2 hours, then loading into a corundum-porcelain boat, and annealing at 500 ℃ for 4 hours in a muffle furnace to obtain the final product of the monocrystal ternary cathode material.
And (3) battery assembly: the prepared positive electrode material, conductive agent acetylene black and binder PVDF are mixed according to the proportion of 8:1:1, and 1.5g of NMP was added to obtain a positive electrode slurry. And (3) after the slurry is fully stirred for 12 hours, uniformly coating the slurry on the carbon-coated aluminum foil with the thickness of 100 mu m to obtain the positive electrode plate. The pole piece was dried in a vacuum oven at 80 ℃ for 12 hours to remove the solvent, and then the dried pole piece was cut into a circular positive pole piece with a diameter of 12 mm. The prepared positive electrode sheet was mixed with a positive electrode having a diameter of 19mm and a thickness of 2. Mu.mThe PP diaphragm of the lithium ion battery pack is formed by superposing lithium sheets with the diameter of 16mm and the thickness of 0.5mm, and the volume ratio of dropwise adding solvent is EC: DEC: dmc=1: 1:1 and contains 1mol/L LiPF 6 The electrolyte solution of the electrolyte salt was assembled into a CR2032 coin cell in a glove box.
And (3) battery testing: and (3) using a CT2001A battery test system of the Wuhan blue electric company to test the cycle performance of the button battery at 25 ℃, wherein the test multiplying power is 1C and 0.5C respectively, and the test voltage range is 3-4.3V.
The test results of this example are as follows: SEM results show that the obtained sample is octahedral monocrystal particles, has regular geometric shape and good morphology (see figure 2); TEM results show that the obtained sample has regular and clear lattice fringes; XRD results show that the sample has good crystallinity, the intensity ratio of the (003) peak to the (104) peak is 2.01, and the lithium nickel mixed discharge degree is lower; the cycle times-specific capacity results show that the 150 th cycle of the obtained sample still has a high specific capacity of 167.2mAh/g at 0.5C, and the capacity retention rate reaches 92.3%; the voltage-specific capacity result shows that the obtained sample still has the specific capacity of 178.2mAh/g at the 50 th cycle of 1.0C, and the voltage platform is stable.
Example 2:
a method for preparing a monocrystal ternary cathode material based on a bi-component fluxing agent comprises the following steps:
single crystal ternary cathode material LiNi 0.55 Co 0.15 Mn 0.3 O 2 Is prepared from the following steps: 4.58g Ni 0.55 Co 0.15 Mn 0.3 (OH) 2 And (3) placing 1.32g of LiOH in a mortar for mixing to obtain a precursor-lithium source mixed material. Another 1.00g Li 2 CO 3 With 8.00g Li 2 SO 4 Mixing in another mortar to obtain the double-component fluxing agent. 7.67g of the bi-component fluxing agent is taken and added into the precursor-lithium source mixed material, and the mixture is fully ground and uniformly mixed. The resulting material was charged into a corundum porcelain boat and calcined in a muffle furnace at 900 c for 10 hours. The calcined material was placed in a mortar for pulverization and grinding, transferred to a beaker, added with 60.78g of deionized water, magnetically stirred and washed for 1min, and then poured into a sand core funnel filled with filter paper for suction filtration. Putting the material after suction filtration into a vacuumDrying in an empty oven at 120 ℃ for 2 hours, then loading into a corundum porcelain boat, and annealing in a muffle furnace at 550 ℃ for 4 hours to obtain the final product of the monocrystal ternary cathode material.
Other steps in this example are the same as those in example 1.
The test results of this example are as follows: SEM results show that the obtained sample is octahedral monocrystal particles, has regular geometric shape and good appearance; TEM results show that the obtained sample has regular and clear lattice fringes (see FIG. 3); XRD results show that the sample has good crystallinity, the intensity ratio of the (003) peak to the (104) peak is 1.87, and the lithium nickel mixed discharge degree is lower; the cycle times-specific capacity results show that the 150 th cycle of the obtained sample still has high specific capacity of 162.4mAh/g at 0.5C, and the capacity retention rate reaches 90.5%; the voltage-specific capacity result shows that the obtained sample still has the specific capacity of 177.5mAh/g at the 50 th cycle of 1.0C, and the voltage platform is stable.
Example 3:
a method for preparing a monocrystal ternary cathode material based on a bi-component fluxing agent comprises the following steps:
single crystal ternary cathode material LiNi 0.5 Co 0.2 Mn 0.3 O 2 Is prepared from the following steps: 4.58g Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 1.32g LiOH was mixed in a mortar to obtain a precursor-lithium source mixture. Another 1.00g Li 2 CO 3 With 9.00g Li 2 SO 4 Mixing in another mortar to obtain the double-component fluxing agent. 7.08g of the bi-component fluxing agent is taken and added into the precursor-lithium source mixed material, and the mixture is fully ground and uniformly mixed. The resulting material was charged into a corundum porcelain boat and calcined in a muffle furnace at 1000 ℃ for 11h. The calcined material was placed in a mortar for pulverization and grinding, transferred to a beaker, added with 57.82g of deionized water, magnetically stirred and washed for 1min, and then poured into a sand core funnel filled with filter paper for suction filtration. And (3) placing the material subjected to suction filtration into a vacuum oven, drying at 120 ℃ for 2 hours, then loading into a corundum-porcelain boat, and annealing at 550 ℃ for 5 hours in a muffle furnace to obtain the final product of the monocrystal ternary cathode material.
Other steps in this example are the same as those in example 1.
The test results of this example are as follows: SEM results show that the obtained sample is octahedral monocrystal particles, has regular geometric shape and good appearance; TEM results show that the obtained sample has regular and clear lattice fringes; XRD results show that the sample has good crystallinity, the intensity ratio of (003) peak to (104) peak is 2.05, and the lithium nickel mixed discharge degree is lower (see figure 4); the cycle times-specific capacity results show that the 150 th cycle of the obtained sample still has a high specific capacity of 164.3mAh/g at 0.5C, and the capacity retention rate reaches 90.2%; the voltage-specific capacity result shows that the obtained sample still has the specific capacity of 179.8mAh/g at the 50 th cycle of 1.0C, and the voltage platform is stable.
Example 4:
a method for preparing a monocrystal ternary cathode material based on a bi-component fluxing agent comprises the following steps:
single crystal ternary cathode material LiNi 0.5 Co 0.2 Mn 0.3 O 2 Is prepared from the following steps: 4.58g Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 1.32g LiOH was mixed in a mortar to obtain a precursor-lithium source mixture. Another 1.00g Li 2 CO 3 With 9.00g Li 2 SO 4 Mixing in another mortar to obtain the double-component fluxing agent. 7.67g of the bi-component fluxing agent is taken and added into the precursor-lithium source mixed material, and the mixture is fully ground and uniformly mixed. The resulting material was charged into a corundum porcelain boat and calcined in a muffle furnace at 1000 ℃ for 12h. The calcined material was placed in a mortar for pulverization and grinding, transferred to a beaker, added with 60.59g of deionized water, magnetically stirred and washed for 1min, and then poured into a sand core funnel filled with filter paper for suction filtration. And (3) placing the material subjected to suction filtration into a vacuum oven, drying at 120 ℃ for 2 hours, then loading into a corundum-porcelain boat, and annealing at 600 ℃ for 5 hours in a muffle furnace to obtain the final product of the monocrystal ternary cathode material.
Other steps in this example are the same as those in example 1.
The test results of this example are as follows: SEM results show that the obtained sample is octahedral monocrystal particles, has regular geometric shape and good appearance; TEM results show that the obtained sample has regular and clear lattice fringes; XRD results show that the sample has good crystallinity, the intensity ratio of the (003) peak to the (104) peak is 1.92, and the lithium nickel mixed discharge degree is low; the cycle times-specific capacity results show that the 150 th cycle of the obtained sample still has high specific capacity of 159.1mAh/g at 0.5C, and the capacity retention rate reaches 93.0 percent (see figure 5); the voltage-specific capacity result shows that the obtained sample still has the specific capacity of 170.5mAh/g at the 50 th cycle of 1.0C, and the voltage platform is stable.
Example 5:
a method for preparing a monocrystal ternary cathode material based on a bi-component fluxing agent comprises the following steps:
single crystal ternary cathode material LiNi 0.6 Co 0.2 Mn 0.2 O 2 Is prepared from the following steps: 4.60g Ni 0.6 Co 0.2 Mn 0.2 (OH) 2 1.32g LiOH was mixed in a mortar to obtain a precursor-lithium source mixture. Another 1.00g Li 2 CO 3 With 10.00g Li 2 SO 4 Mixing in another mortar to obtain the double-component fluxing agent. 7.11g of the bi-component fluxing agent is taken and added into the precursor-lithium source mixed material, and the mixture is fully ground and uniformly mixed. The resulting material was charged into a corundum porcelain boat and calcined in a muffle furnace at 950 ℃ for 13h. The calcined material was placed in a mortar for pulverization and grinding, transferred to a beaker, added with 58.22g of deionized water, magnetically stirred and washed for 1min, and then poured into a sand core funnel filled with filter paper for suction filtration. And (3) placing the material subjected to suction filtration into a vacuum oven, drying at 120 ℃ for 2 hours, then loading into a corundum-porcelain boat, and annealing at 600 ℃ for 6 hours in a muffle furnace to obtain the final product of the monocrystal ternary cathode material.
Other steps in this example are the same as those in example 1.
The test results of this example are as follows: SEM results show that the obtained sample is octahedral monocrystal particles, has regular geometric shape and good appearance; TEM results show that the obtained sample has regular and clear lattice fringes; XRD results show that the sample has good crystallinity, the intensity ratio of the (003) peak to the (104) peak is 1.99, and the lithium nickel mixed discharge degree is lower; the cycle times-specific capacity results show that the 150 th cycle of the obtained sample still has a high specific capacity of 162.8mAh/g at 0.5C, and the capacity retention rate reaches 90.3%; the voltage-specific capacity results show that the obtained sample still has a specific capacity of 178.3mAh/g at 1.0C for the 50 th cycle, and the voltage platform is stable (see FIG. 6).
Example 6:
a method for preparing a monocrystal ternary cathode material based on a bi-component fluxing agent comprises the following steps:
single crystal ternary cathode material LiNi 0.6 Co 0.2 Mn 0.2 O 2 Is prepared from the following steps: 4.60g Ni 0.6 Co 0.2 Mn 0.2 (OH) 2 1.32g LiOH was mixed in a mortar to obtain a precursor-lithium source mixture. Another 1.00g Li 2 CO 3 With 10.00g Li 2 SO 4 Mixing in another mortar to obtain the double-component fluxing agent. 7.67g of the bi-component fluxing agent is taken and added into the precursor-lithium source mixed material, and the mixture is fully ground and uniformly mixed. The resulting material was charged into a corundum porcelain boat and calcined in a muffle furnace at 950 ℃ for 14h. The calcined material was placed in a mortar for pulverization and grinding, transferred to a beaker, added with 61.02g of deionized water, magnetically stirred and washed for 1min, and then poured into a sand core funnel filled with filter paper for suction filtration. And (3) placing the material subjected to suction filtration into a vacuum oven, drying at 120 ℃ for 2 hours, then loading into a corundum-porcelain boat, and annealing at 650 ℃ for 6 hours in a muffle furnace to obtain the final product of the monocrystal ternary cathode material.
Other steps in this example are the same as those in example 1.
The test results of this example are as follows: SEM results show that the obtained sample is octahedral monocrystal particles, has regular geometric shape and good appearance; TEM results show that the obtained sample has regular and clear lattice fringes; XRD results show that the sample has good crystallinity, the intensity ratio of the (003) peak to the (104) peak is 1.98, and the lithium nickel mixed discharge degree is low; the cycle times-specific capacity results show that the 150 th cycle of the obtained sample still has a high specific capacity of 168.4mAh/g at 0.5C, and the capacity retention rate reaches 92.7%; the voltage-specific capacity result shows that the obtained sample still has the specific capacity of 173.5mAh/g at the 50 th cycle of 1.0C, and the voltage platform is stable.
Example 7:
a method for preparing a single crystal ternary cathode material based on a multi-component flux, comprising the steps of:
single crystal ternary cathode material LiNi 0.5 Co 0.2 Mn 0.3 O 2 Is prepared from the following steps: 4.58g Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 1.32g LiOH was mixed in a mortar to obtain a precursor-lithium source mixture. Another 1.00g Li 2 CO 3 With 9.00g Li 2 SO 4 With 0.2g of lithium oxalate C 2 Li 2 O 4 Placing the mixture in another mortar for mixing to obtain the multi-component fluxing agent. 7.67g of the multicomponent fluxing agent is taken and added into the precursor-lithium source mixed material, and the mixture is fully ground and uniformly mixed. The resulting material was charged into a corundum porcelain boat and calcined in a muffle furnace at 1000 ℃ for 12h. The calcined material was placed in a mortar for pulverization and grinding, transferred to a beaker, added with 60.59g of deionized water, magnetically stirred and washed for 1min, and then poured into a sand core funnel filled with filter paper for suction filtration. And (3) placing the material subjected to suction filtration into a vacuum oven, drying at 120 ℃ for 2 hours, then loading into a corundum-porcelain boat, and annealing at 600 ℃ for 5 hours in a muffle furnace to obtain the final product of the monocrystal ternary cathode material.
Other steps in this example are the same as those in example 1.
The test results of this example are as follows: SEM results show that the obtained sample is octahedral monocrystal particles, the geometric shape is more regular and sharp, and the sample has excellent morphological characteristics; TEM results show that the obtained sample has regular and clear lattice fringes; XRD results show that the sample has good crystallinity, the intensity ratio of the (003) peak to the (104) peak is 2.10, and the lithium nickel mixed discharge degree is low; the cycle times-specific capacity results show that the 150 th cycle of the obtained sample still has high specific capacity of 178.6mAh/g at 0.5C, and the capacity retention rate reaches 95.8%; the voltage-specific capacity result shows that the obtained sample still has the specific capacity of 181.2mAh/g at the 50 th cycle of 1.0C, and the voltage platform is stable.
Example 8:
a method for preparing a single crystal ternary cathode material based on a multi-component flux, comprising the steps of:
single crystal ternary cathode material LiNi 0.55 Co 0.15 Mn 0.3 O 2 Is prepared from the following steps: 4.58g Ni 0.55 Co 0.15 Mn 0.3 (OH) 2 And (3) placing 1.32g of LiOH in a mortar for mixing to obtain a precursor-lithium source mixed material. Another 1.00g Li 2 CO 3 With 8.00g Li 2 SO 4 With 0.3g of lithium oxalate C 2 Li 2 O 4 Placing in another mortar for mixing, and adding a multi-component fluxing agent. 7.67g of the multicomponent fluxing agent is taken and added into the precursor-lithium source mixed material, and the mixture is fully ground and uniformly mixed. The resulting material was charged into a corundum porcelain boat and calcined in a muffle furnace at 900 c for 10 hours. The calcined material was placed in a mortar for pulverization and grinding, transferred to a beaker, added with 60.78g of deionized water, magnetically stirred and washed for 1min, and then poured into a sand core funnel filled with filter paper for suction filtration. And (3) placing the material subjected to suction filtration into a vacuum oven, drying at 120 ℃ for 2 hours, then loading into a corundum-porcelain boat, and annealing at 550 ℃ for 4 hours in a muffle furnace to obtain the final product of the monocrystal ternary cathode material.
Other steps in this example are the same as those in example 1.
The test results of this example are as follows: SEM results show that the obtained sample is octahedral monocrystal particles, the geometric shape is more regular and sharp, and the sample has excellent morphological characteristics; TEM results show that the obtained sample has regular and clear lattice fringes; XRD results show that the sample has good crystallinity, the intensity ratio of (003) peak to (104) peak is 2.23, and the lithium nickel mixing degree is lower; the cycle times-specific capacity results show that the 150 th cycle of the obtained sample still has a high specific capacity of 183.7mAh/g at 0.5C, and the capacity retention rate reaches 98.2%; the voltage-specific capacity result shows that the obtained sample still has the specific capacity of 185.1mAh/g at the 50 th cycle of 1.0C, and the voltage platform is stable.
Example 9:
a method for preparing a single crystal ternary cathode material based on a multi-component flux, comprising the steps of:
single crystal ternary cathode material LiNi 0.6 Co 0.2 Mn 0.2 O 2 Is prepared from the following steps: 4.60g Ni 0.6 Co 0.2 Mn 0.2 (OH) 2 1.32g LiOH was placed in a mortarAnd (3) mixing to obtain a precursor-lithium source mixed material. Another 1.00g Li 2 CO 3 With 10.00g Li 2 SO 4 With 0.5g of lithium oxalate C 2 Li 2 O 4 Placing in another mortar for mixing, and adding a multi-component fluxing agent. 7.67g of the multicomponent fluxing agent is taken and added into the precursor-lithium source mixed material, and the mixture is fully ground and uniformly mixed. The resulting material was charged into a corundum porcelain boat and calcined in a muffle furnace at 950 ℃ for 14h. The calcined material was placed in a mortar for pulverization and grinding, transferred to a beaker, added with 61.02g of deionized water, magnetically stirred and washed for 1min, and then poured into a sand core funnel filled with filter paper for suction filtration. And (3) placing the material subjected to suction filtration into a vacuum oven, drying at 120 ℃ for 2 hours, then loading into a corundum-porcelain boat, and annealing at 650 ℃ for 6 hours in a muffle furnace to obtain the final product of the monocrystal ternary cathode material.
Other steps in this example are the same as those in example 1.
The test results of this example are as follows: SEM results show that the obtained sample is octahedral monocrystal particles, has regular geometric shape and good appearance; TEM results show that the obtained sample has regular and clear lattice fringes; XRD results show that the sample has good crystallinity, the intensity ratio of the (003) peak to the (104) peak is 2.18, and the lithium nickel mixed discharge degree is lower; the cycle times-specific capacity results show that the 150 th cycle of the obtained sample still has a high specific capacity of 179.8mAh/g at 0.5C, and the capacity retention rate reaches 94.3%; the voltage-specific capacity result shows that the obtained sample still has the specific capacity of 182.4mAh/g at the 50 th cycle of 1.0C, and the voltage platform is stable.
Comparative example 1:
a method for preparing a monocrystal ternary positive electrode material without a fluxing agent comprises the following steps:
single crystal ternary cathode material LiNi 0.6 Co 0.2 Mn 0.2 O 2 Is prepared from the following steps: 4.60g of Ni which is a special precursor for preparing single crystal ternary cathode material 0.6 Co 0.2 Mn 0.2 (OH) 2 (which can be prepared by using the preparation process in CN 110718688A), and 1.32g of LiOH are placed in a mortar for mixing, so as to obtain a precursor-lithium source mixed material. Loading the obtained material into corundum porcelain boat, and placing in muffle furnaceCalcining at 950 ℃ for 14h. And then annealing for 6 hours at 650 ℃ in a muffle furnace to obtain the final product of the monocrystal ternary cathode material.
The other steps in this comparative example were the same as in example 1.
The test results of this comparative example are as follows: SEM results show that the obtained sample is a round particle, the geometric shape is nearly spherical, and the shape is poor; TEM results show that the obtained sample has staggered lattice stripes, and grain boundaries are visible in the grains; XRD results show that the sample has poor crystallinity, the intensity ratio of the (003) peak to the (104) peak is 1.02, and the lithium nickel has higher mixing degree; the cycle times-specific capacity results show that the 150 th cycle of the obtained sample at 0.5C has the specific capacity of 140.7mAh/g and the capacity retention rate is only 74.5%; the voltage-specific capacity result shows that the obtained sample only has a specific capacity of 158.3mAh/g in the 50 th cycle at 1.0C, and the platform inclination is large.
Comparative example 2:
a method for preparing a monocrystal ternary cathode material based on a single-component fluxing agent comprises the following steps:
(1) Single crystal ternary cathode material LiNi 0.6 Co 0.2 Mn 0.2 O 2 Is prepared from the following steps: 4.60g Ni 0.6 Co 0.2 Mn 0.2 (OH) 2 And (3) placing 1.32g of LiOH in a mortar for mixing to obtain a precursor-lithium source mixed material. Another 7.67g Li 2 CO 3 As a single-component fluxing agent, the single-component fluxing agent is added into the precursor-lithium source mixed material, and is fully ground and uniformly mixed. The resulting material was charged into a corundum porcelain boat and calcined in a muffle furnace at 950 ℃ for 14h. The calcined material was placed in a mortar for pulverization and grinding, transferred to a beaker, added with 61.02g of deionized water, magnetically stirred and washed for 1min, and then poured into a sand core funnel filled with filter paper for suction filtration. And (3) placing the material subjected to suction filtration into a vacuum oven, drying at 120 ℃ for 2 hours, then loading into a corundum-porcelain boat, and annealing at 650 ℃ for 6 hours in a muffle furnace to obtain the final product of the monocrystal ternary cathode material.
The other steps in this comparative example were the same as in example 1.
The test results of this comparative example are as follows: SEM results show that the obtained samples are irregular polygonal particles, the geometric shapes are broken plate blocks, and the shapes are poor; TEM results show that lattice fringes of the obtained sample are mixed, and a large number of cracks are formed on the surface of the particles; XRD results show that the sample has poor crystallinity, the intensity ratio of the (003) peak to the (104) peak is 1.05, and the lithium nickel has higher mixing degree; the cycle times-specific capacity results show that the 150 th cycle of the obtained sample at 0.5C has the specific capacity of 133.8mAh/g and the capacity retention rate is 67.3%; the voltage-specific capacity results show that the obtained sample has a specific capacity of 155.6mAh/g only in the 50 th cycle at 1.0C, and the platform inclination is large.
Comparative example 3:
a method for preparing a monocrystal ternary cathode material based on a bi-component fluxing agent comprises the following steps:
single crystal ternary cathode material LiNi 0.55 Co 0.15 Mn 0.3 O 2 Is prepared from the following steps: 4.58g Ni 0.55 Co 0.15 Mn 0.3 (OH) 2 And (3) placing 1.32g of LiOH in a mortar for mixing to obtain a precursor-lithium source mixed material. Another 4.00g Li 2 CO 3 With 4.00g Li 2 SO 4 Mixing in another mortar to obtain the double-component fluxing agent. 7.67g of the bi-component fluxing agent is taken and added into the precursor-lithium source mixed material, and the mixture is fully ground and uniformly mixed. The resulting material was charged into a corundum porcelain boat and calcined in a muffle furnace at 900 c for 10 hours. The calcined material was placed in a mortar for pulverization and grinding, transferred to a beaker, added with 60.78g of deionized water, magnetically stirred and washed for 1min, and then poured into a sand core funnel filled with filter paper for suction filtration. And (3) placing the material subjected to suction filtration into a vacuum oven, drying at 120 ℃ for 2 hours, then loading into a corundum-porcelain boat, and annealing at 550 ℃ for 4 hours in a muffle furnace to obtain the final product of the monocrystal ternary cathode material.
The other steps in this comparative example were the same as in example 1.
The test results of this comparative example are as follows: SEM results show that the obtained sample is similar to octahedral monocrystal particles, the geometric shape is not regular, and the shape is medium; TEM results show that the obtained sample lattice fringes are slightly blurred; XRD results show that the sample crystallinity is general, the intensity ratio of the (003) peak to the (104) peak is 1.53, and the lithium nickel mixed discharge degree is slightly lower; the cycle times-specific capacity results show that the 150 th cycle of the obtained sample has a specific capacity of 150.9mAh/g at 0.5C, and the capacity retention rate is 81.1%; the voltage-specific capacity results show that the obtained sample has a specific capacity of 163.5mAh/g at 1.0C for the 50 th cycle, and the voltage platform is slightly inclined.
Comparative example 4:
a method for preparing a monocrystal ternary cathode material based on a bi-component fluxing agent comprises the following steps:
single crystal ternary cathode material LiNi 0.5 Co 0.2 Mn 0.3 O 2 Is prepared from the following steps: 4.58g Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 1.32g LiOH was mixed in a mortar to obtain a precursor-lithium source mixture. Another 10.00g Li 2 CO 3 And 0.2gC 2 Li 2 O 4 Mixing in another mortar to obtain Li-deficient powder 2 SO 4 A two-component fluxing agent of components. 7.67g of the multicomponent fluxing agent is taken and added into the precursor-lithium source mixed material, and the mixture is fully ground and uniformly mixed. The resulting material was charged into a corundum porcelain boat and calcined in a muffle furnace at 1000 ℃ for 12h. The calcined material was placed in a mortar for pulverization and grinding, transferred to a beaker, added with 60.59g of deionized water, magnetically stirred and washed for 1min, and then poured into a sand core funnel filled with filter paper for suction filtration. And (3) placing the material subjected to suction filtration into a vacuum oven, drying at 120 ℃ for 2 hours, then loading into a corundum-porcelain boat, and annealing at 600 ℃ for 5 hours in a muffle furnace to obtain the final product of the monocrystal ternary cathode material.
The other steps in this comparative example were the same as in example 1.
The test results of this comparative example are as follows: SEM results show that the obtained samples are polycrystalline particles, the geometric shapes of the samples are spheroidal particles consisting of irregular single crystals, and the morphological characteristics of the samples are poor; TEM results show that the obtained sample is a polycrystalline sample; XRD results show that the sample crystallinity is general, the intensity ratio of the (003) peak to the (104) peak is 1.57, and the lithium nickel mixed discharge degree is slightly lower; the cycle times-specific capacity results show that the 150 th cycle of the obtained sample only has the specific capacity of 133.2mAh/g at 0.5C, and the capacity retention rate is 56.3%; the voltage-specific capacity result shows that the 50 th cycle of the obtained sample at 1.0C only has the specific capacity of 155.4mAh/g, and the voltage platform is inclined greatly.
Comparative example 5:
a method for preparing a monocrystal ternary cathode material based on a bi-component fluxing agent comprises the following steps:
single crystal ternary cathode material LiNi 0.5 Co 0.2 Mn 0.3 O 2 Is prepared from the following steps: 4.58g Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 1.32g LiOH was mixed in a mortar to obtain a precursor-lithium source mixture. Another 10.00g Li 2 SO 4 And 0.2gC 2 Li 2 O 4 Mixing in another mortar to obtain Li-deficient powder 2 CO 3 A two-component fluxing agent of components. 7.67g of the multicomponent fluxing agent is taken and added into the precursor-lithium source mixed material, and the mixture is fully ground and uniformly mixed. The resulting material was charged into a corundum porcelain boat and calcined in a muffle furnace at 1000 ℃ for 12h. The calcined material was placed in a mortar for pulverization and grinding, transferred to a beaker, added with 60.59g of deionized water, magnetically stirred and washed for 1min, and then poured into a sand core funnel filled with filter paper for suction filtration. And (3) placing the material subjected to suction filtration into a vacuum oven, drying at 120 ℃ for 2 hours, then loading into a corundum-porcelain boat, and annealing at 600 ℃ for 5 hours in a muffle furnace to obtain the final product of the monocrystal ternary cathode material.
The other steps in this comparative example were the same as in example 1.
The test results of this comparative example are as follows: SEM results show that the obtained sample is similar to octahedral monocrystal particles, the geometric shape is not regular, and the shape is medium; TEM results show that grain boundaries exist in the obtained sample, and part of grains have cracks inside; XRD results show that the sample has moderate crystallinity, the intensity ratio of (003) peak to (104) peak is 1.72, and the lithium nickel mixed discharge degree is slightly lower; the cycle times-specific capacity results show that the 150 th cycle of the obtained sample has a specific capacity of 151.6mAh/g at 0.5C, and the capacity retention rate is 82.5%; the voltage-specific capacity result shows that the 50 th cycle of the obtained sample at 1.0C has the specific capacity of 159.5mAh/g, and the voltage platform is stable.
Comparative example 6:
a method for preparing a single crystal ternary cathode material based on a multi-component flux, comprising the steps of:
single crystal ternary cathode material LiNi 0.5 Co 0.2 Mn 0.3 O 2 Is prepared from the following steps: 4.58g Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 1.32g LiOH was mixed in a mortar to obtain a precursor-lithium source mixture. Another 1.00g Li 2 CO 3 With 9.00g Li 2 SO 4 And 0.2g Na 2 SO 4 Placing the mixture in another mortar for mixing to obtain the multi-component fluxing agent. 7.67g of the multicomponent fluxing agent is taken and added into the precursor-lithium source mixed material, and the mixture is fully ground and uniformly mixed. The resulting material was charged into a corundum porcelain boat and calcined in a muffle furnace at 1000 ℃ for 12h. The calcined material was placed in a mortar for pulverization and grinding, transferred to a beaker, added with 60.59g of deionized water, magnetically stirred and washed for 1min, and then poured into a sand core funnel filled with filter paper for suction filtration. And (3) placing the material subjected to suction filtration into a vacuum oven, drying at 120 ℃ for 2 hours, then loading into a corundum-porcelain boat, and annealing at 600 ℃ for 5 hours in a muffle furnace to obtain the final product of the monocrystal ternary cathode material.
The other steps in this comparative example were the same as in example 1.
The test results of this comparative example are as follows: the flux was found to melt incompletely during the comminution of the product. SEM results show that the obtained sample is octahedral monocrystal particles, the geometric shape is more regular, and the shape is better; TEM results show that the obtained sample has clearer lattice stripes; XRD results show that the sample crystallinity is general, the intensity ratio of the (003) peak to the (104) peak is 1.62, and the sample has slightly lower lithium nickel miscibility; the electrochemical performance of the sample is poor, and the result of the cycle times and the specific capacity shows that the 150 th cycle of the obtained sample at 0.5 ℃ only has the specific capacity of 54.5mAh/g, and the capacity retention rate is 46.1%; the voltage-specific capacity results show that the obtained sample has a specific capacity of only 71.3mAh/g at 1.0C for the 50 th cycle, and does not have a voltage plateau.
Comparative example 7:
a method for preparing a single crystal ternary cathode material based on a multi-component flux, comprising the steps of:
single crystal ternary cathode material LiNi 0.5 Co 0.2 Mn 0.3 O 2 Is prepared from the following steps: 4.58g Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 1.32g LiOH was mixed in a mortar to obtain a precursor-lithium source mixture. Another 1.00g Li 2 CO 3 With 9.00g Li 2 SO 4 With 0.2g of lithium oxalate C 2 Li 2 O 4 Placing the mixture in another mortar for mixing to obtain the multi-component fluxing agent. 7.67g of the multicomponent fluxing agent is taken and added into the precursor-lithium source mixed material, and the mixture is fully ground and uniformly mixed. The resulting material was charged into a corundum porcelain boat and calcined in a muffle furnace at 1100 c for 12 hours. The calcined material was placed in a mortar for pulverization and grinding, transferred to a beaker, added with 60.59g of deionized water, magnetically stirred and washed for 1min, and then poured into a sand core funnel filled with filter paper for suction filtration. And (3) placing the material subjected to suction filtration into a vacuum oven, drying at 120 ℃ for 2 hours, then loading into a corundum-porcelain boat, and annealing at 400 ℃ for 5 hours in a muffle furnace to obtain the final product of the monocrystal ternary cathode material.
The other steps in this comparative example were the same as in example 1.
The test results of this comparative example are as follows: SEM results show that the obtained sample is a broken octahedral single crystal particle, the geometric shape is broken, and the surface has a large number of cracks; TEM results show that the surface structure of the obtained sample is not lamellar phase, more rock salt phase exists, a large number of cracks exist, and grain boundaries exist inside; XRD results show that the sample crystallinity is general, the intensity ratio of the (003) peak to the (104) peak is 0.94, and the lithium nickel mixing degree is high; the cycle times-specific capacity results show that the 150 th cycle capacity of the obtained sample rapidly decays to a low specific capacity of 45.4mAh/g at 0.5C, and the capacity retention rate is only 48.7%; the voltage-specific capacity results show that the 50 th cycle of the obtained sample at 1.0C only has the specific capacity of 90.5mAh/g, and the voltage platform rapidly disappears.
The phase properties and electrochemical properties of the positive electrode materials obtained in each example and comparative example are compared with each other, and the results are shown in tables 1 and 2:
table 1: comparison of the phase Properties and electrochemical Properties of the Positive electrode materials obtained in examples 1 to 9
Table 2: comparison of the phase Properties and electrochemical Properties of the Positive electrode materials obtained in comparative examples 1 to 7
The results show that the monocrystal ternary cathode material prepared by the preparation method provided by the invention has better phase performance and electrochemical performance compared with the monocrystal ternary cathode material prepared by a monocomponent fluxing agent without a fluxing agent.
Claims (5)
1. The preparation method of the monocrystal ternary anode material is characterized by comprising the following steps of:
(1) Nickel cobalt manganese hydroxide precursor Ni 1-x-y Co x Mn y (OH) 2 Mixing with a lithium source to obtain a mixed material A;
(2) Mixing the mixed material A obtained in the step (1) with a fluxing agent to obtain a mixed material B; the fluxing agent is Li 2 CO 3 With Li 2 SO 4 Is a mixture of (a) and (b);
(3) Calcining the mixed material B obtained in the step (2), and then crushing, grinding, washing, drying and annealing to obtain a monocrystal ternary anode material;
the fluxing agent is Li 2 CO 3 With Li 2 SO 4 The mass ratio is 1: (8.0-10.0);
the fluxing agent also contains lithium oxalate, wherein the Li 2 CO 3 The mass ratio of the lithium oxalate to the lithium oxalate is 1: (0.2-0.5).
2. The method of claim 1, wherein the lithium source is LiOH, and the nickel cobalt manganese hydroxide precursor Ni is controlled 1-x-y Co x Mn y (OH) 2 The molar ratio to the lithium source is 1: (1.05-1.10).
3. The preparation method according to claim 1, wherein the mass ratio of the mixture A to the fluxing agent is 1: (1.2-1.3).
4. The preparation method according to claim 1, wherein the calcination treatment is performed at a calcination temperature of 900-1000 ℃ for 10-14 hours.
5. The preparation method according to claim 1, wherein the annealing temperature is controlled to be 500-650 ℃ and the annealing time is controlled to be 4-6h during the annealing treatment.
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| CN109921009A (en) * | 2019-03-11 | 2019-06-21 | 苏州拉瓦锂能源科技有限公司 | A kind of preparation method of single crystal battery material |
| CN110336007A (en) * | 2019-07-08 | 2019-10-15 | 苏州拉瓦锂能源科技有限公司 | A kind of monocrystalline type battery material and preparation method thereof |
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| CN109921009A (en) * | 2019-03-11 | 2019-06-21 | 苏州拉瓦锂能源科技有限公司 | A kind of preparation method of single crystal battery material |
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