CN116190552A - Li (lithium ion battery) 2 B 4 O 7 Preparation method of LiF co-coated high-nickel NCM lithium ion battery anode material - Google Patents

Li (lithium ion battery) 2 B 4 O 7 Preparation method of LiF co-coated high-nickel NCM lithium ion battery anode material Download PDF

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CN116190552A
CN116190552A CN202310152178.7A CN202310152178A CN116190552A CN 116190552 A CN116190552 A CN 116190552A CN 202310152178 A CN202310152178 A CN 202310152178A CN 116190552 A CN116190552 A CN 116190552A
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lithium ion
ion battery
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ncm811
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樊新
周晓琳
秦琳
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Guilin University of Technology
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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
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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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/02—Electrodes composed of, or comprising, active material
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    • H—ELECTRICITY
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    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
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    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • 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
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Abstract

The invention relates to the technical field of mobile electronic equipment batteries, electric vehicles and hybrid electric vehicle lithium ion batteries, in particular to a lithium ion battery Li 2 B 4 O 7 A preparation method of LiF co-coated high nickel cobalt lithium manganate (NCM) lithium ion battery anode material. The invention synthesizes Li 2 B 4 O 7 And LiBF as a raw material for LiF coating 4 Directly mixing with NCM positive electrode materialSubsequently by evaporating the solvent and sintering, liBF is obtained 4 React with residual lithium on the surface of NCM positive electrode material to generate Li 2 B 4 O 7 And LiF, and directly coat on the surface of the material, the method has simple process, uniform coating, difficult agglomeration of the coating agent, difficult falling off after coating and stable coating. After coating, the generation of HF in the electrolyte and the corrosion to the positive electrode material can be prevented, and the storage performance, the interface stability and the interface ion diffusion capacity of the material are enhanced to a certain extent, so that the performance of the NCM ternary positive electrode material is improved.

Description

Li (lithium ion battery) 2 B 4 O 7 Preparation method of LiF co-coated high-nickel NCM lithium ion battery anode material
Technical Field
The invention relates to the technical field of lithium ion batteries of electric vehicles and hybrid electric vehicles, in particular to Li 2 B 4 O 7 The preparation method of the LiF co-coated high-nickel NCM lithium ion battery anode material.
Background
Increasing the mileage of commercial lithium ion battery-type electric vehicles and hybrid electric vehicles is the focus of current research, and the core is to increase the energy density of lithium ion batteries, which is closely related to battery materials, particularly positive electrode materials. The ternary positive electrode material integrates LiCoO better due to the ternary synergistic effect 2 、LiNiO 2 And LiMnO 2 The three commercial positive electrode materials have the advantages that the performance is superior to that of any single-component material, and the ternary positive electrode material becomes one of the positive electrode materials with the most development potential of electric vehicles and hybrid electric vehicles. However, the lithium-nickel composite material still has some defects, such as rapid capacity decay, poor rate capability, battery gas production, poor normal-temperature and high-temperature cycle performance and the like caused by mixed discharge of residual lithium and lithium nickel on the surface, and the large-scale application of the lithium-nickel composite material is greatly hindered.
The surface coating is a common modification method, wherein the coating modification is mainly to improve the cycle performance by reducing the contact area between the positive electrode material and the electrolyte, and the common surface coating material is oxide (such as Al 2 O 3 、B 2 O 3 、Zr0 2 Etc.), fluorides (e.g. AlF 3 Etc.), phosphate (e.g. LiPO 4 、AlPO 4 、LaPO 4 Etc.), carbon materials (e.g., graphene, carbon nanotubes, etc.), and conductive polymers (e.g., PPy, etc.), etc. Most coating materials are insulators of ions and electrons, and the cycle performance and the multiplying power performance of the materials cannot be improved, and a fast ion conductor can well solve the phenomenon. Therefore, the development of fast ion conductor coating materials has become a trend for modification.
Li formed on the surface of the cathode material 2 B 4 O 7 Belongs to a fast ion conductor of lithium ions, and is favorable for fast intercalation/deintercalation of lithium ions compared with residual lithium compounds. In addition，Li 2 B 4 O 7 The solid electrolyte with high lithium ion concentration can effectively reduce the activation energy required for exciting the intercalation/deintercalation of lithium ions on the surface of the material, and can improve the cycle and the rate capability of the high-nickel NCM anode material.
LiF formed on the surface of the positive electrode material belongs to the important component of CEI film of high nickel NCM positive electrode material, and can effectively control electrolyte LiPF 6 Thereby reducing the generation of HF and erosion of the positive electrode material, and can improve the cycling stability of the high nickel NCM positive electrode material.
However, the common coating means is usually to directly dry mix the coating with the ternary cathode material and then calcine the mixture, which has a certain degree of drawbacks such as easy agglomeration of the coating, poor coating uniformity, low conductivity, low stability and the like.
Therefore, the high-nickel NCM positive electrode material with excellent electrochemical performance prepared by adopting common and good-effect raw materials and simple and uniformly-coated and stable synthesis operation has great significance for application in the fields of electric automobiles and hybrid electric automobiles.
Disclosure of Invention
The object of the present invention is to provide Li 2 B 4 O 7 The preparation method of the LiF co-coated high-nickel NCM lithium ion battery anode material. The problems of rapid capacity attenuation, gas production of the battery and the like caused by high content of residual lithium of the anode material of the high-nickel NCM lithium ion battery in the prior art are solved.
In order to achieve the above object, the present invention provides the following solutions:
li (lithium ion battery) 2 B 4 O 7 -LiF co-coated high nickel NCM lithium ion battery positive electrode material, said material being prepared by the following method steps:
first, lithium tetrafluoroborate (LiBF 4 ) Adding absolute ethyl alcohol, uniformly dispersing by ultrasonic, adding high nickel NCM ternary positive electrode material, stirring at 30 ℃ for 30min, heating to 90 ℃ until the absolute ethyl alcohol is removed, calcining the obtained material in oxygen atmosphere, and obtaining Li after calcining 2 B 4 O 7 -LiFCo-cladding a high nickel NCM lithium ion battery anode material;
further, the high-nickel NCM ternary positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O 2 。
Further, high nickel NCM ternary positive electrode material and added LiBF 4 The molar ratio of the dosage is 1 (0.005-0.01).
Further, the ultrasonic mixing frequency is 40kHz and the time is 30min.
Further, the calcination refers to calcination for 10 hours at a temperature rising rate of 5 ℃/min to 500 ℃.
Another object of the present invention is to provide Li prepared by the method 2 B 4 O 7 LiF co-coats the high nickel NCM lithium ion battery anode material.
Compared with the prior art, the invention has the beneficial effects that:
(1) The invention uses LiBF 4 As a coating precursor, li is generated by utilizing the reaction between the coating precursor and the residual lithium on the surface of the high-nickel NCM ternary positive electrode material 2 B 4 O 7 And the LiF co-coating layer effectively relieves the influence of residual lithium on the high-nickel NCM ternary positive electrode material.
(2) Li prepared by the invention 2 B 4 O 7 Compared with other single metal boride or fluoride coating layers, the LiF co-coating layer has better lithium ion conductivity, corrosion resistance and wear resistance, can resist the attack of HF, and ensures that the material has good cycle performance and rate capability.
(3) The invention adopts a simple wet cladding synthesis method to generate firm Li in situ 2 B 4 O 7 And the LiF co-coating layer is uniform and firm and has good stability. Compared with the defect that the surface of the anode material is easy to have poor stability when being coated by post treatment in the prior art, the method generates Li in situ 2 B 4 O 7 The method of co-coating with LiF is advantageous for improving its stability and electrochemical properties.
(4) The method is simple and convenient, has low cost, realizes the development concept of low cobalt in the field of lithium ion batteries, and is favorable for large-scale production and social acceptance.
Drawings
FIG. 1 shows XRD patterns of the end products NCM811, NCM811@LBF-0.5, NCM811@LBF-0.7 and NCM811@LBF-1 prepared in comparative examples and examples 1 to 3.
FIG. 2 is a graph comparing XPS spectra of the end products NCM811 and NCM811@LBF-0.7 prepared in comparative example and example 2.
FIG. 3 is a Scanning Electron Microscope (SEM) image of the end products NCM811 and NCM811@LBF-0.7 prepared in comparative example and example 2.
FIG. 4 shows the EDS surface scan test results of the end product NCM811@LBF-0.7 of example 2,
FIG. 5 is a Transmission Electron Microscope (TEM) image of the end products NCM811 and NCM811@LBF-0.7 prepared in comparative example and example 2.
FIG. 6 is a graph of the first-turn charge-discharge capacity vs. voltage for the end products NCM811 and NCM811@LBF-0.7 prepared in comparative example and example 2.
FIG. 7 is a schematic graph showing the cycle performance of the end products NCM811, NCM811@LBF-0.5, NCM811@LBF-0.7 and NCM811@LBF-1 prepared in comparative examples and examples 1 to 3 at 0.5C, 3-4.3V.
FIG. 8 is a graph showing the cycle performance at 1C,3-4.3V of the end products NCM811, NCM811@LBF-0.5, NCM811@LBF-0.7 and NCM811@LBF-1 prepared in comparative examples and examples.
FIG. 9 is a graph showing the rate performance of the end products NCM811, NCM811@LBF-0.5, NCM811@LBF-0.7 and NCM811@LBF-1 prepared in comparative examples and examples 1 to 3.
FIG. 10 is a Scanning Electron Microscope (SEM) image of comparative example NCM811 cycled 300 times at 1C, 3.0V-4.3V.
FIG. 11 is a Scanning Electron Microscope (SEM) image of the end product NCM811@LBF-0.7 prepared in example 2 cycled 300 turns at 1C, 3.0V-4.3V.
Detailed Description
Various exemplary embodiments of the invention will now be described in detail, which should not be considered as limiting the invention, but rather as more detailed descriptions of certain aspects, features and embodiments of the invention.
It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In addition, for numerical ranges in this disclosure, it is understood that each intermediate value between the upper and lower limits of the ranges is also specifically disclosed. Every smaller range between any stated value or stated range, and any other stated value or intermediate value within the stated range, is also encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.
It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the invention described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from consideration of the specification of the present invention. The specification and examples are exemplary only.
As used herein, the terms "comprising," "including," "having," "containing," and the like are intended to be inclusive and mean an inclusion, but not limited to.
In the following comparative examples and examples:
(1) The pH meter is the Shanghai Lei Ci instrument PHS-3C.
(2) Scanning Electron Microscope (SEM) test instrument model Zeiss Gemini Sigma Germany 300.
(3) Energy Spectrometry (EDS) test instrument model Zeiss Gemini Sigma Germany.
(4) Transmission Electron Microscope (TEM) test instrument model is Titan G2 60-300 type transmission electron microscope of FEI company.
(5) CR2016 button cell assembly and testing: cathode material (final product prepared in comparative example or example), acetylene black, polyvinylidene fluoride (PVDF) were slurried in a mass ratio of 8:1:1 and drop wise with an appropriate amount of N-methylpyrrolidone (NMP) and coated on aluminum foil, and the aluminum foil loaded with the slurry was vacuum dried in a vacuum oven at 110℃for 12 hours. The dried aluminum foil loaded with the slurry was cut into small disks having a diameter of about 12mm by a cutter to be used as a positive electrode. LiPF with metallic lithium sheet as negative electrode, celgard2400 as separator, 1M 6 And (3) dissolving the mixture solution of Ethylene Carbonate (EC), dimethyl carbonate (DMC) and Ethyl Methyl Carbonate (EMC) in a volume ratio of 1:1:1, and assembling the mixture solution into the CR2016 button battery in an argon glove box.
(6) And carrying out constant current charge and discharge tests on the assembled CR2016 button battery under different current densities by adopting a Xinwei CT-4008-5V20A-A battery tester, wherein the current density of 1C is defined to be 180mAh/g, the charge and discharge voltage interval is 3.0V-4.3V, and the test temperature is 30 ℃.
Comparative example
Commercial LiNi offered by Haian Ichwan company 0.8 Co 0.1 Mn 0.1 O 2 The material was a comparative example, designated NCM811.
Example 1
0.0482g of lithium tetrafluoroborate (LiBF 4 Aladin) was added to 50mL of absolute ethanol, placed in an ultrasonic cleaner, sonicated at 40kHz for 30min, and 10g of the NCM811 material of comparative example (NCM 811 and LiBF were added 4 The molar ratio of (2) is 1: 0.005). Stirring at 30deg.C for 30min, heating to 90deg.C until anhydrous ethanol is evaporated, placing the obtained powder into an oxygen-introducing atmosphere protection box furnace, heating to 500deg.C at a heating rate of 5deg.C/min, calcining for 10 hr, and obtaining final product Li after calcining 2 B 4 O 7 LiF co-coated high nickel NCM lithium ion battery anode material is marked as NCM811@LBF-0.5.
Example 2
0.0647g of lithium tetrafluoroborate (LiBF 4 Aladin) was added to 50mL of absolute ethanol, placed in an ultrasonic cleaner, sonicated at 40kHz for 30min, and 10g of the NCM811 material of comparative example (NCM 811 and LiBF were added 4 The molar ratio of (2) is 1: 0.007). Stirring at 30deg.C for 30min, heating to 90deg.C until anhydrous ethanol is evaporated, placing the obtained powder into an oxygen-introducing atmosphere protection box furnace, heating to 500deg.C at a heating rate of 5deg.C/min, calcining for 10 hr, and obtaining final product Li after calcining 2 B 4 O 7 LiF co-coated high nickel NCM lithium ion battery anode material is marked as NCM811@LBF-0.7.
Example 3
0.0964g of lithium tetrafluoroborate (LiBF 4 Aladin) was added to 50mL of absolute ethanol, placed in an ultrasonic cleaner, sonicated at 40kHz for 30min, and 10g of the NCM811 material of comparative example (NCM 811 and LiBF were added 4 The molar ratio of (2) is 1: 0.01). Stirring at 30deg.C for 30min, heating to 90deg.C until anhydrous ethanol is evaporated, placing the obtained powder into an oxygen-introducing atmosphere protection box furnace, heating to 500deg.C at a heating rate of 5deg.C/min, calcining for 10 hr, and obtaining final product Li after calcining 2 B 4 O 7 LiF co-coated high nickel NCM lithium ion battery anode material is marked as NCM811@LBF-1.
Application example
(1) The NCM811@LBF-0.5 material, NCM811@LBF-0.7 material, NCM811@LBF-1 material obtained in example 1 and NCM811 material obtained in comparative example 1 were mixed with conductive carbon black (Super-P, aldine) and polyvinylidene fluoride (PVDF, sigma-Aldrich) respectively according to a mass ratio of 8:1:1, and N-methylpyrrolidone (NMP) was added and stirred uniformly. The obtained mixed slurry was uniformly coated on an aluminum foil, and was dried in an oven at 110 ℃ for 12 hours and cut into a circular positive electrode sheet with a diameter of 12mm to prepare battery test performance.
(2) LiPF with metallic lithium sheet as negative electrode, celgard2400 as separator and electrolyte as 1M 6 And (3) dissolving the mixture solution of Ethylene Carbonate (EC), dimethyl carbonate (DMC) and Ethyl Methyl Carbonate (EMC) in a volume ratio of 1:1:1, and assembling the mixture solution into the CR2016 button battery in an argon glove box.
(3) And carrying out constant current charge and discharge tests on the assembled CR2016 button battery under different current densities by adopting a Xinwei CT-4008-5V20A-A battery tester, wherein the current density of 1C is defined to be 180mAh/g, the charge and discharge voltage interval is 3.0V-4.3V, and the test temperature is 30 ℃.
2g of the end products prepared in comparative example and example 2, NCM811 and NCM811@LBF-0.7, respectively, were dissolved in 30mL of deionized water, and after stirring at 200rpm for 30min at room temperature, the pH values of the supernatants were tested to give NCM811 and NCM811@LBF-0.7 of pH 12.06 and 11.68, respectively. This means Li 2 B 4 O 7 The preparation method of the LiF co-coated high-nickel NCM lithium ion battery anode material can obviously reduce the residual alkali content on the surface of the NCM811 material. .
FIG. 1 shows XRD patterns of the end products NCM811, NCM811@LBF-0.5, NCM811@LBF-0.7 and NCM811@LBF-1 prepared in comparative examples and examples 1 to 3. Four groups of end products were all identical to NCM811
Hexagonal layered alpha-NaNiO (PDF#09-0063) 2 (R-3 m space group) structure perfectly matches, indicating that
The cladding process does not alter the overall lattice structure of NCM811. The ratio of the intensities of the four groups of end product (003) and (104) peaks is 0.9982,1.08071,1.35659 and 1.62101, respectively, indicating that the coating process can improve lithium nickel misce bene and is in a proportional relationship.
FIG. 2 is a graph comparing XPS spectra of the end products NCM811 and NCM811@LBF-0.7 prepared in comparative example and example 2. FIG. 2b is a C1 s spectrum, which can be divided into three characteristic peaks 289.5 eV, 284.8 eV and 286.4 eV, corresponding to CO respectively 3 2- C-C and C=O, NCM811@LBF-0.7 is superior to NCM811, CO 3 2- The peak area ratio of (2) was reduced from 24.31% to 12.42%, and it was also confirmed that the O1 s spectrum in FIG. 2c, the characteristic peaks at 531.7, eV and 529.3 eV respectively belong to impurity oxygen (Li 2 CO 3 O in (a) - ，O 2- And CO 2 3- ) And lattice oxygen (TM-O, m=ni, co, mn). The peak area ratio of impurity oxygen in NCM811@LBF-0.7 was reduced from 81.5% to 74.9% compared to NCM811, mainly due to the consumption of surface Li by the coating means 2 CO 3 And (5) impurities. Furthermore, it can be seen in the Ni 2p spectrum in FIG. 2d that the surface of NCM811 detects Ni 2+ More than NCM811@LBF-0.7, ni in NCM811 3+ And Ni 2+ The contents were 40.27% and 59.72%, respectively, and the contents of NCM811@LBF-0.7 were 60.13% and 39.86%, respectively, indicating that the composition was prepared by Li 2 B 4 O 7 Co-cladding with LiF reduces Ni on the surface of NCM811 material 2+ The formation of lithium nickel mixed discharge and NiO rock salt is reduced, thereby contributing to the improvement of the surface stability of NCM811. The peak in the B1 s spectrum of FIG. 2e at 192.3eV is assigned to Li 2 B 4 O 7 The method comprises the steps of carrying out a first treatment on the surface of the The peak in the F1 s spectrum of FIG. 2F, located at 685.3eV, is assigned to LiF, which illustrates Li 2 B 4 O 7 Successful synthesis of LiF and coating of the NCM811 surface to form Li 2 B 4 O 7 LiF co-coats the high nickel NCM lithium ion battery anode material.
FIG. 3 is a Scanning Electron Microscope (SEM) image of the end products NCM811 and NCM811@LBF-0.7 prepared in comparative example and example 2, where it can be seen that both end products are of secondary particle spherical morphology.
FIG. 4 shows the EDS surface scan test results of the end product NCM811@LBF-0.7 of example 2, B was undetectable for instrument reasons. However, a uniform distribution of Ni, co, mn, F was clearly observed, indicating that the compound containing element F successfully formed a coating on the surface of the material.
FIG. 5 is a Transmission Electron Microscope (TEM) image of the end products NCM811 and NCM811@LBF-0.7 prepared in comparative example and example 2, where a is NCM811 prepared in comparative example and b is NCM811@LBF-0.7 prepared in example 2. The spacing of the lattice fringes in FIG. 5a is about 0.239nm, corresponding to the (0 1 2) plane (I region) of NCM811, while the (0 1 2) plane (II region) of NCM811 is still detectable in FIG. 5b, while it is evident that the material surface has a coating layer of about 4 to 6nm in thickness, in which the components ascribed to LiF (1 1 1) plane (III region) and Li are detectable 2 B 4 O 7 Lattice fringes of the (4 0 0) plane (iv region). This indicates Li 2 B 4 O 7 LiF successfully coats the NCM811 material surface.
FIG. 6 is a comparative example and exampleThe first-turn charge-discharge capacity-voltage curves of the end products NCM811 and NCM811@LBF-0.7 prepared in example 2, as can be seen, were obtained by Li 2 B 4 O 7 Co-cladding with LiF, the first-turn coulombic efficiency increased from 84.6% to 87.1%.
FIG. 7 is a schematic graph showing the cycle performance of the end products NCM811, NCM811@LBF-0.5, NCM811@LBF-0.7 and NCM811@LBF-1 prepared in comparative examples and examples 1 to 3 at 0.5C, 3-4.3V. After 170 cycles, the capacity retention rates are 63.05%,77.88%,87.53% and 58.78%, respectively, and it can be seen that the Li 2 B 4 O 7 The preparation method of the LiF co-coated high-nickel NCM lithium ion battery anode material has obvious improvement on the cycle stability.
FIG. 8 is a graph showing the cycle performance at 1C,3-4.3V of the end products NCM811, NCM811@LBF-0.5, NCM811@LBF-0.7 and NCM811@LBF-1 prepared in comparative examples and examples. After 300 cycles, the capacity retention rates were 30.96%,55.98%,69.76% and 46.83%, respectively, which can be further confirmed that the Li 2 B 4 O 7 The preparation method of the LiF co-coated high-nickel NCM lithium ion battery anode material has obvious improvement on the cycle stability.
FIG. 9 shows the average discharge capacity retention rates of the final products NCM811, NCM811@LBF-0.5, NCM811@LBF-0.7 and NCM811@LBF-1 prepared in comparative examples and examples 1 to 3 at different rates, and it can be seen that the present Li 2 B 4 O 7 The preparation method of the LiF co-coated high-nickel NCM lithium ion battery anode material has obvious improvement on the cycle stability.
FIG. 10 is a Scanning Electron Microscope (SEM) image of comparative example NCM811 cycled 300 cycles at 1C, 3.0V-4.3V, showing severe breakage of the material structure, which allows electrolyte to easily penetrate into the bulk material along cracks and penetrate the NCM83 anode along grain boundaries, resulting in the conversion of the active layered structure into an irreversible rock salt phase, accelerating loss of active species.
FIG. 11 is a Scanning Electron Microscope (SEM) image of the final product NCM811@LBF-0.7 prepared in example 2, cycled 300 turns at 1C,3.0V to 4.3V, in which no significant cracks were observed, demonstrating Li 2 B 4 O 7 The LiF co-cladding can inhibit volume change caused by lattice distortion, improve the stability of the crystal structure of the positive electrode material of the high-nickel NCM lithium ion battery, and reduce the generation of cracks.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the particular embodiments disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Claims (6)

1. Li (lithium ion battery) 2 B 4 O 7 The preparation method of the LiF co-coated high-nickel NCM lithium ion battery anode material is characterized by comprising the following steps:
1) High nickel NCM lithium ion battery positive electrode material and LiBF 4 Ultrasonic mixing is carried out in ethanol according to a proportion, and then the ethanol is evaporated;
2) Calcining to obtain Li 2 B 4 O 7 And LiF coated high nickel NCM lithium ion battery positive electrode material.
2. A Li according to claim 1 2 B 4 O 7 The preparation method of the LiF co-coated high-nickel NCM lithium ion battery anode material is characterized in that the ternary anode material is a high-nickel NCM811 anode material.
3. A Li according to claim 1 2 B 4 O 7 The preparation method of the LiF co-coated high-nickel NCM lithium ion battery anode material is characterized by comprising the steps of 4 The molar ratio of the dosage is 1 (0.005-0.01).
4. A Li according to claim 1 2 B 4 O 7 The preparation method of the LiF co-coated high-nickel NCM lithium ion battery anode material is characterized in that the ultrasonic mixing frequency in the step 1) is 40kHz, and the time is 30min.
5. A Li according to claim 1 2 B 4 O 7 LiF co-packageThe preparation method of the high nickel-coated NCM lithium ion battery positive electrode material is characterized in that the calcination in the step 2) is to heat up to 500 ℃ for 10 hours at a heating rate of 5 ℃/min under an oxygen atmosphere.
6. A Li according to any one of claims 1-5 2 B 4 O 7 And LiF coated high nickel NCM lithium ion battery positive electrode material.
CN202310152178.7A 2023-02-22 2023-02-22 Li (lithium ion battery) 2 B 4 O 7 Preparation method of LiF co-coated high-nickel NCM lithium ion battery anode material Pending CN116190552A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116768282A (en) * 2023-08-15 2023-09-19 湖南长远锂科新能源有限公司 High-temperature high-rate lithium cobaltate and preparation method thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116768282A (en) * 2023-08-15 2023-09-19 湖南长远锂科新能源有限公司 High-temperature high-rate lithium cobaltate and preparation method thereof
CN116768282B (en) * 2023-08-15 2024-07-16 湖南长远锂科新能源有限公司 High-temperature high-rate lithium cobaltate and preparation method thereof

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