CN115602827B - Cobalt-free positive electrode material, preparation method, battery and electric equipment - Google Patents

Cobalt-free positive electrode material, preparation method, battery and electric equipment Download PDF

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CN115602827B
CN115602827B CN202211597757.4A CN202211597757A CN115602827B CN 115602827 B CN115602827 B CN 115602827B CN 202211597757 A CN202211597757 A CN 202211597757A CN 115602827 B CN115602827 B CN 115602827B
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cobalt
free
polymer layer
value
layer
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CN115602827A (en
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郭丰
乔齐齐
李子郯
杨红新
施泽涛
王鹏飞
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Svolt Energy Technology Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
    • C01C3/00—Cyanogen; Compounds thereof
    • C01C3/08—Simple or complex cyanides of metals
    • C01C3/11—Complex cyanides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/40—Nickelates
    • C01G53/42—Nickelates containing alkali metals, e.g. LiNiO2
    • C01G53/44—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
    • C01P2002/86—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by NMR- or ESR-data
    • 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 application discloses a cobalt-free positive electrode material, a preparation method, a battery and electric equipment. The cobalt-free cathode material comprises a high nickel material, wherein a polymer layer and a Prussian blue material layer are arranged on the surface of the high nickel material, and the Prussian blue material layer is positioned on the surface of the polymer layer; the chemical formula of the high nickel material is Li x Ni y Mn 1‑y O 2 Wherein x is more than or equal to 1 and less than or equal to 1.1, y is more than or equal to 0.9 and less than or equal to 0.98, and the cycle performance of the anode material is improved. The preparation method of the cathode material comprises the following steps: preparing a high nickel material with a polymer layer; preparing a prussian blue material layer on the surface of the polymer layer. According to the preparation method of the anode material, the polymer layer and the Prussian blue material layer are prepared on the surface of the high-nickel material, so that the surface residual alkali of the cobalt-free anode material is reduced, and the cycle stability of the cobalt-free anode material is improved.

Description

Cobalt-free positive electrode material, preparation method, battery and electric equipment
Technical Field
The application relates to the technical field of batteries, in particular to a cobalt-free positive electrode material, a preparation method of the cobalt-free positive electrode material, a battery and electric equipment.
Background
Since the first generation of Lithium Ion Batteries (LIBs), the layered transition metal oxide material has been the preferred material for the positive electrode of the battery due to its advantages of high theoretical capacity, outstanding rate capability, relatively stable two-dimensional Li + diffusion channel, etc. Since the positive electrode material is the most critical component affecting the battery cost and the battery capacity, the high cost of Co element makes it difficult to meet the requirements of large-scale energy storage devices and electric automobiles. In recent years, a cobalt-free positive electrode material has received much attention, and lithium nickel manganese oxide (NM) and lithium nickel manganese cobalt (NCM) having the same Ni content exhibit equivalent discharge capacity at 0.1C, while NM exhibits better cycle stability and thermal stability with respect to NCM. In the high nickel positive electrode material, the effect of the Co element is further weakened. However, the high-nickel cobalt-free cathode material generally has the defects of poor cyclicity and high residual alkali, so that the improvement of the cycling stability of the high-nickel cathode material and the reduction of the residual alkali are of great significance for developing the battery with long endurance mileage.
Disclosure of Invention
The application aims to provide a cobalt-free positive electrode material, a preparation method, a battery and electric equipment. According to the method, the polymer layer and the Prussian blue material layer are arranged on the surface of the high-nickel material, so that the surface residual alkali of the cobalt-free anode material is reduced, and the circulating stability of the cobalt-free anode material is improved.
The embodiment of the application provides a cobalt-free cathode material, which comprises a high nickel material, wherein the surface of the high nickel material is provided with a polymer layer and a prussian blue material layer, and the prussian blue material layer is positioned on the surface of the polymer layer; the chemical formula of the high nickel material is Li x Ni y Mn 1-y O 2 Wherein x is more than or equal to 1 and less than or equal to 1.1, and y is more than or equal to 0.9 and less than or equal to 0.98.
In some embodiments, the thickness of the prussian blue material layer is 150 to 300nm.
In some embodiments, the polymer layer comprises a polymer having pendant cyano groups.
In some embodiments, the polymer comprises polyacrylonitrile.
In some embodiments, the polymer layer and the high nickel material are in mass percent: 0.01% -0.5%.
In some embodiments, the positive electrode material satisfies: 0.01A is less than or equal to LD is less than or equal to 0.2A, wherein LD is c-axis lattice deviation.
Correspondingly, the embodiment of the application further provides a preparation method of the cobalt-free cathode material, which comprises the following steps:
(S1) preparing a high nickel material with a polymer layer;
(S2) preparing a prussian blue material layer on the surface of the polymer layer.
In some embodiments, the high nickel material with a polymer layer is prepared by: taking a precursor Ni y Mn 1-y (OH) 2 Adding the polymer into a polymer monomer solution, stirring, drying, mixing with lithium salt, and sintering for the first time to obtain the high nickel material with a polymer layer.
In some embodiments, the first sintering is divided into two-stage sintering: the first stage sintering is as follows: heating to a temperature T 1 Keeping the temperature for 3 to 6h 1 At 200-300 deg.C; the second stage sintering comprises: from T 1 Heating to a temperature T 2 Keeping the temperature for 6 to 10 hours 2 The temperature is 650 ℃ to 750 ℃.
In some embodiments, the precursor Ni y Mn 1-y (OH) 2 XRD of (1) satisfies: the D value is 2.5 to 3.5, the Q value is 0.5 to 2, the W value is 0.8 to 1.5, wherein the D value is the ratio of 001 characteristic peak strength to 100 characteristic peak strength, the Q value is the angle range occupied by the 001 characteristic peak half-peak width correspondingly, and the W value is the angle range occupied by the 100 characteristic peak half-peak width correspondingly.
In some embodiments, the polymer monomer comprises acrylonitrile.
In some embodiments, the prussian blue-based material layer is prepared by: adding the high nickel material with the polymer layer and sodium ferrocyanide into the acrylonitrile solution, stirring, filtering, and sintering for the second time to obtain the cobalt-free anode material.
In some embodiments, the temperature of the second sintering is 200 ℃ to 300 ℃, and the holding time is 6 to 10 hours.
Accordingly, embodiments of the present application further provide a battery including the cobalt-free positive electrode material or the cobalt-free positive electrode material prepared by the preparation method.
Accordingly, embodiments of the present application further provide an electric device including the battery described above.
The beneficial effect of this application lies in: the application provides a positive electrode material, which comprises a high nickel material and a high nickel material surfaceThe Prussian blue type material layer is positioned on the surface of the polymer layer; the chemical formula of the high nickel material is Li x Ni y Mn 1-y O 2 Wherein x is more than or equal to 1 and less than or equal to 1.1, and y is more than or equal to 0.9 and less than or equal to 0.98. The polymer layer is prepared on the surface of the high-nickel material, so that the surface of the positive electrode material is stabilized, and the cycle performance of the positive electrode material is improved; the surface of the polymer layer is further provided with the Prussian blue material layer, so that the surface residual alkali of the high-nickel anode material is reduced, the phase change of the high-nickel anode material in the circulating process is inhibited, and the circulating stability of the cobalt-free anode material is further improved.
Drawings
Fig. 1 is a Li-site NMR spectrum chart of the cathode materials synthesized in example 1 and comparative example 1.
Detailed Description
The technical solutions of the present application will be described below clearly and completely in conjunction with the embodiments and the accompanying drawings of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application. Various embodiments of the present application may exist in a range of forms; it should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the application; accordingly, the described range descriptions should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range. For example, it is contemplated that the description of a range from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as individual numbers within a range of numbers, such as 1, 2, 3, 4, 5, and 6, for example, regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any number (fractional or integer) recited within the range so indicated.
In order to solve the defect that the high-nickel cathode material in the prior art generally has poor cyclicity, the embodiment of the application provides a cathode materialThe cobalt-free cathode material comprises a high nickel material, wherein a polymer layer and a Prussian blue material layer are arranged on the surface of the high nickel material, and the Prussian blue material layer is positioned on the surface of the polymer layer; the chemical formula of the high nickel material is Li x Ni y Mn 1-y O 2 Wherein x is more than or equal to 1 and less than or equal to 1.1, and y is more than or equal to 0.9 and less than or equal to 0.98.
In some embodiments, x has a value of any of 1.0, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.1, or a range consisting of any two thereof.
In some embodiments, x ranges from 1.02 to 1.08.
This application has polymer layer at nickelic material surface cladding, has stabilized the surface structure of cathode material, has improved the contact stability of cathode material and electrolyte, and then has improved cathode material's circulation stability ability. According to the method, the prussian blue material layer is coated on the surface of the polymer layer, so that the surface residual alkali of the high-nickel material is reduced, the phase change of the high-nickel material in the circulating process is inhibited, and the circulating stability of the high-nickel material is further improved.
In some embodiments, the thickness of the prussian blue material layer is 150 to 300nm.
The thickness of the Prussian blue material layer on the surface of the anode material is larger than 300nm, so that a lithium ion transmission channel is blocked, and the rate performance is poor. The thickness of the Prussian blue material layer on the surface of the cathode material is less than 150nm, so that the cycle performance of the cathode material is poor.
In some embodiments, the thickness (nm) of the prussian blue-based material layer is any of 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300 or a range consisting of any two of them.
In some embodiments, the layer of prussian blue-like material includes prussian blue sodium (Na) i Mn z Mn(CN) 6 ·nH 2 O) and/or potassium Prussian blue (K) i Mn z Mn(CN) 6 ·nH 2 O), wherein the value of i ranges from 1 to 1.4, and the value of z ranges from 0.8 to 1.
In some embodiments, the polymer layer comprises a polymer having pendant cyano groups.
The cyano group is introduced into the side group of the polymer, and the cyano group has strong electronegativity, so that the metal ions (Li) can be effectively solidified + 、Ni 2+ 、Mn 2+ ) The Li/Ni mixed arrangement is reduced, the crystal lattice is fixed to prevent the Li/Ni mixed arrangement from being deformed, and the rate capability of the anode material is improved.
In some embodiments, the polymer comprises polyacrylonitrile.
In some embodiments, the polymer layer and the high nickel material are in the following mass percentages: 0.01% -0.5%.
The polymer layer on the surface of the high-nickel material has too much content, so that the integral rate capability and the cycle performance of the high-nickel material as a positive active substance are deteriorated, and the polymer layer on the surface of the high-nickel material has too low content, so that the surface of the positive active material cannot be better stabilized, and the integral rate capability and the cycle performance of the positive active material are also deteriorated.
In some embodiments, the polymer layer and the high nickel material are in the following mass percentages: 0.1-0.4% and 0.1-0.35%.
In some embodiments, the mass percentages (%) of the polymer layer to the high nickel material are: 0.11, 0.12, 0.13, 0.15, 0.17, 0.18, 0.19, 0.20, 0.21, 0.24, 0.32, or a range of any two values.
In some embodiments, the cobalt-free cathode material satisfies: 0.01A is less than or equal to LD is less than or equal to 0.2A, wherein LD is c-axis lattice deviation.
In some embodiments, the cobalt-free cathode material satisfies: 0.02A is less than or equal to LD is less than or equal to 0.2A, wherein LD is c-axis lattice deviation.
In some embodiments, the cobalt-free cathode material has an LD value (a) of any of 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, or a range consisting of any two values.
In some embodiments, the c-axis lattice deviation is calculated by the following formula: LD is the difference between the actual c-axis parameter and the standard c-axis parameter.
In some embodiments, the parameters of the actual c-axis are measured by XRD.
In some embodiments, the cathode material is prepared by: preparing a high nickel material with a polymer layer; and preparing a prussian blue material layer on the surface of the polymer layer.
In some embodiments, the high nickel material with the polymer layer is prepared by: taking a precursor Ni y Mn 1-y (OH) 2 Adding the mixture into polymer monomer solution, stirring, drying, mixing with lithium salt, and sintering for the first time to obtain the high nickel material with a polymer layer.
In some embodiments, the first sintering is divided into two-stage sintering: the first stage sintering comprises: heating to a temperature T 1 Keeping the temperature for 3 to 6h 1 At 200-300 ℃; the second stage sintering comprises: from T 1 Heating to temperature T 2 Keeping the temperature for 6 to 10 hours 2 The temperature is 650 ℃ to 750 ℃.
In some embodiments, T 1 The temperature (DEG C) is any value or a range consisting of any two values of 200, 210, 220, 230, 240, 250, 260, 270, 280, 290 and 300.
In some embodiments, at T 1 The holding time (h) at the temperature is as follows: 3. 4, 5, 6, or a range of any two of them.
In some embodiments, T 2 (° c) is any value or a range of any two of 650, 660, 670, 680, 690, 700, 710, 720, 730, 740, and 750.
In some embodiments, at T 2 The holding time (h) at the temperature is as follows: 6. any value or range of any two of 7, 8, 9, and 10.
In some embodiments, the precursor Ni y Mn 1-y (OH) 2 XRD of (1) satisfies: the D value is 2.5 to 3.5, the Q value is 0.5 to 2, the W value is 0.8 to 1.5, wherein the D value is the ratio of 001 characteristic peak strength to 100 characteristic peak strength, the Q value is the angle range occupied by the 001 characteristic peak half-peak width correspondingly, and the W value is the angle range occupied by the 100 characteristic peak half-peak width correspondingly.
According to the method, the lattice deformation and displacement of the synthesized anode material can be effectively improved by optimizing the crystal parameters of the precursor, and the particle strength is improved, so that the circulation stability is improved. When the W value is too high, the Li/Ni mixed discharge of the anode material is seriously deteriorated in rate capability, and when the W value is too low, the Mn element is segregated, so that the cycle performance of the anode material is deteriorated. The Q value influences the particle strength of the material, and the cycling stability of the material is influenced by over-high or under-low of the Q value.
In some embodiments, the polymer monomer comprises acrylonitrile.
In some embodiments, the precursor Ni y Mn 1-y (OH) 2 The mass ratio of the acrylonitrile solution to the acrylonitrile solution is 0.2 to 0.5.
In some embodiments, the precursor Ni y Mn 1-y (OH) 2 The mass ratio of the acrylonitrile solution to the acrylonitrile solution is within a range of any one or two of 0.2, 0.3, 0.4 and 0.5.
In some embodiments, the concentration of the acrylonitrile solution is 1 to 2mol/L.
In some embodiments, the concentration of the acrylonitrile solution (mol/L) is: 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, or a range of any two of these.
In some embodiments, the solvent of the acrylonitrile solution is methanol.
In some embodiments, the precursor Ni y Mn 1-y (OH) 2 The temperature for stirring the solution and the polymer monomer is 60-80 ℃, and the stirring time is 6-12h.
In some embodiments, the temperature (° c) of the agitation is: 60. any value or range of any two of 65, 70, 75, 80.
In some embodiments, the time (h) of stirring is: 6. any value or range of any two of 7, 8, 9, 10, 11, 12.
In some embodiments, the lithium salt is selected from LiOH, li 2 CO 3 At least one of lithium oxalate, lithium potassium oxide and lithium nitrate.
In some embodiments, the molar number of Li element in the lithium salt to Ni element and Mn element in the precursor satisfies: li (Ni + Mn) = (1.02 to 1.08): 1.
in some embodiments, the prussian blue-based material layer is prepared by:
adding the prepared high nickel material with the polymer layer and sodium ferrocyanide into an acrylonitrile solution, stirring, filtering after stirring, and sintering for the second time to obtain the cobalt-free anode material.
In some embodiments, the temperature of stirring is 60 to 90 ℃, and the stirring time is 6 to 12h.
In some embodiments, the temperature of the second sintering is 200 ℃ to 300 ℃, and the holding time is 6 to 10 hours.
In some embodiments, the temperature (° c) of the agitation is: 60. any value or range of any two of 65, 70, 75, 80, 85, 90.
In some embodiments, the time (h) of stirring is: 6. any value or range of any two of 7, 8, 9, 10, 11, 12.
The embodiment of the application further provides a battery, which comprises a positive pole piece, wherein the positive pole piece comprises a positive current collector and a positive active material layer arranged on the positive current collector, and the positive active material layer comprises the cobalt-free positive material.
In specific implementation, the positive electrode material, the conductive agent, the binder and the solvent are uniformly stirred, and the positive electrode plate is prepared through the working procedures of sieving, coating, rolling, slitting, cutting and the like.
Specifically, the kind of the conductive agent is not limited, and any known conductive agent can be used. Examples of conductive agents may include, but are not limited to, one or more of the following: carbon materials such as natural graphite, artificial graphite, super P conductive carbon black, acetylene black, needle coke, carbon nanotubes, graphene, and the like. The positive electrode conductive agents may be used alone or in any combination.
The type of binder used in the production of the positive electrode active material layer is not particularly limited, and in the case of the coating method, it is sufficient if it is a material that is soluble or dispersible in the liquid medium used in the production of the electrode. Examples of binders may include, but are not limited to, one or more of the following: polyethylene, polypropylene, polyvinylidene fluoride (PVDF), polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and the like. The above binders may be used alone or in any combination thereof.
The type of solvent used to form the positive electrode slurry is not limited as long as it can dissolve or disperse the positive electrode active material, the conductive agent, and the binder. Examples of the solvent used to form the positive electrode slurry may include any one of an aqueous solvent and an organic solvent. Examples of aqueous media may include, but are not limited to: water, mixed media of alcohol and water, and the like. Examples of organic based media may include, but are not limited to: hexane, benzene, toluene, xylene, pyridine, acetone, tetrahydrofuran (THF), N-methylpyrrolidone (NMP), and the like.
Specifically, the battery comprises a positive pole piece, a negative pole piece, an isolation film and electrolyte, wherein the positive pole piece is the positive pole piece. In specific implementation, the positive pole piece, the negative pole piece, the isolating membrane, the electrolyte and the like are assembled into the lithium ion battery. The negative electrode material adopted by the negative electrode plate can be one or more of artificial graphite, natural graphite, mesocarbon microbeads, amorphous carbon, lithium titanate or silicon-carbon alloy.
Embodiments of the present application also provide an electric device including the above battery.
In some embodiments, the powered devices of the present application include, but are not limited to: the power supply comprises a standby power supply, a motor, an electric automobile, an electric motorcycle, a power-assisted bicycle, a bicycle, an electric tool, a household large-scale storage battery and the like.
Example 1: preparation of cobalt-free cathode material
(S1) 100g of a cobalt-free high-nickel precursor Ni with a D value of 3.12, a Q value of 1.02 and a W value of 0.95 are taken 0.95 Mn 0.05 (OH) 2 Adding into 300g1.5mol/L acrylonitrile solution (methanol as solvent), stirring at 70 deg.C for 10 hr, and oven drying at 60 deg.C; uniformly stirring 100g of dried cobalt-free high-nickel precursor and 47.83g of LiOH by using a handheld stirrer, putting the mixture into a box-type atmosphere furnace, sintering at 300 ℃ for 5h, heating to 720 ℃ and sintering for 8h, and naturally sinteringCooling to room temperature to obtain the polyacrylonitrile-coated nickel material.
(S2) adding 100g of prepared polyacrylonitrile-coated high-nickel material and 2.5g of sodium ferrocyanide into 200g of 1.5mol/L acrylonitrile solution (methanol as a solvent), stirring at 80 ℃ for 10h, filtering after stirring, placing into a box-type atmosphere furnace, and sintering at 300 ℃ for 5h to obtain the cobalt-free anode material with 180nm Prussian sodium and 0.05A deviation of C axis lattice in situ growth.
Example 2: the preparation method is the same as that of the example 1, and is different from the example 1 in that: in step (S1): the W value of the cobalt-free precursor was 1.82.
Example 3: the preparation method is the same as that of the example 1, and is different from the example 1 in that: in step (S1): the Q value of the cobalt-free precursor was 3.5.
Example 4: the preparation method is the same as that of the example 1, and is different from the example 1 in that: in step (S1): the Q value of the cobalt-free precursor was 0.3.
Example 5: the preparation method is the same as that of the example 1, and is different from the example 1 in that: in step (S1): the W value of the cobalt-free precursor was 0.6.
Example 6: the preparation method is the same as that of the example 1, and is different from the example 1 in that: in step (S1): the W value of the cobalt-free precursor was 3.0.
Example 7: the preparation method is the same as that of the example 1, and is different from the example 1 in that: in step (S1): the concentration of acrylonitrile was 0.5mol/L.
Example 8: the preparation method is the same as that of the example 1, and is different from the example 1 in that: in step (S1): the concentration of acrylonitrile was 5mol/L.
Example 9: the preparation method is the same as that of the example 1, and is different from the example 1 in that: in step (S1): t is a unit of 1 The temperature was 500 ℃.
Example 10: the preparation method is the same as that of the example 1, and is different from the example 1 in that: in step (S1): t is 1 The temperature was 200 ℃.
Example 11: the preparation method is the same as that of the example 1, and is different from the example 1 in that: in step (S2): the amount of sodium ferrocyanide added was 0.5g.
Example 12: the preparation method is the same as that of the example 1, and is different from the example 1 in that: in step (S2): the amount of sodium ferrocyanide added was 6g.
Example 13: the preparation method is the same as that of the example 1, and is different from the example 1 in that: cobalt-free high nickel precursor Ni 0.95 Mn 0.05 (OH) 2 The D value of (D) was 3.6, the Q value was 1.3, and the W value was 0.9.
Example 14: the preparation method is the same as that of the example 1, and is different from the example 1 in that: cobalt-free high nickel precursor Ni 0.95 Mn 0.05 (OH) 2 Has a D value of 2.7, a Q value of 2.4, and a W value of 1.4.
Example 15: the preparation method is the same as that of the example 1, and is different from the example 1 in that: cobalt-free high nickel precursor Ni 0.95 Mn 0.05 (OH) 2 Has a D value of 1.1, a Q value of 0.7 and a W value of 2.0.
Example 16: the preparation method is the same as example 1, and is different from example 1 in that: cobalt-free high nickel precursor Ni 0.95 Mn 0.05 (OH) 2 Has a D value of 3.6, a Q value of 0.3, and a W value of 1.6.
Comparative example 1: 100g of cobalt-free high nickel precursor Ni with a D value of 3.12, a Q value of 1.02 and a W value of 0.95 are taken 0.95 Mn 0.05 (OH) 2 And uniformly stirring 47.83g of LiOH by using a handheld stirrer, putting the mixture into a box-type atmosphere furnace, sintering the mixture for 5 hours at the temperature of 300 ℃, heating the mixture to 720 ℃, sintering the mixture for 8 hours, and naturally cooling the mixture to room temperature to obtain the high-nickel material.
Comparative example 2: the preparation method is the same as example 1 except that the coating of the prussian blue-based material layer in the step (S2) is not performed.
Comparative example 3: (S1) 100g of a cobalt-free high-nickel precursor Ni with a D value of 3.12, a Q value of 1.02 and a W value of 0.95 are taken 0.95 Mn 0.05 (OH) 2 With 47.83g of LiOH, 0.4737g of ZrO 2 Uniformly stirring by using a handheld stirrer, putting into a box-type atmosphere furnace, heating to 720 ℃, preserving heat for 10 hours, cooling and reducing to room temperature;
(S2) taking 100g of the powder prepared in the step (S1)Cobalt positive electrode material and 0.3g ZrO 2 、0.2g TiO 2 Uniformly mixing, putting into a box-type atmosphere furnace, preserving the heat for 5h at 400 ℃, cooling to room temperature to obtain the conventional coated cobalt-free cathode material.
And (4) performance testing:
and (4) buckling and assembling: a metal lithium sheet is used as a negative electrode, a positive electrode piece is prepared by using the positive electrodes prepared in examples 1 to 16 and comparative examples 1 to 3, NMP is used as a solvent, and the weight ratio of a positive electrode material, a binder (PVDF) and a conductive agent (SP) is 96:2:2, after being uniformly mixed, the two surfaces of the mixture are coated on an aluminum foil, the solid content of the PVDF glue solution is 6.05 percent, the thickness of the aluminum foil is 12 mu m, the purity is more than 99 percent, and the pole piece is compacted to be 3.3g/cm 3 The button half cells were assembled with celgard 2325 separator in a vacuum glove box. And (3) carrying out performance test on the assembled button cell, wherein the test method comprises the following steps:
1C/0.1C specific discharge capacity: the 1C specific discharge capacity was: the same applies to the 1C discharge capacity/active material quantity and 0.1C discharge specific capacity of the battery.
Capacity retention at 1C for 50 weeks: under the conditions of 1C charging and 1C discharging, the ratio of the 1C discharging specific capacity to the first circle 1C discharging specific capacity after 50 times of charging and discharging is obtained.
The total residual alkali amount test method comprises the following steps: determination of magnetic foreign matter content and residual alkali content in GBT lithium ion battery anode material detection method
Table 1 shows the results of the performance tests (charge cut-off voltage of 4.3V, discharge cut-off voltage of 3.0V, and nominal gram capacity of 200 mAh/g) for examples 1 to 16 and comparative examples 1 to 3.
Figure 987981DEST_PATH_IMAGE002
From the results of examples 1 to 16, comparative examples 1 to 3 and figure 1, it can be seen that polyacrylonitrile is synthesized on the surface of the high-nickel material, so that the surface structure of the positive electrode material is stabilized, li/Ni mixed emission is reduced, and the cycle stability of the positive electrode material is improved. The Prussian blue sodium layer is further synthesized on the surface of the polymer layer, the surface residual alkali of the high-nickel anode material can be reduced, and the phase change process of the high-nickel anode material in the circulating process can be restrained on the other hand, so that the circulating stability of the high-nickel anode material is improved. After the prussian blue sodium is coated on the cobalt-free high-nickel cathode material, the special pore structure on the surface can ensure that the structure is damaged in the battery charging and discharging process, the special structure of the prussian blue material has a certain elastic mechanism and can effectively relieve the volume strain and improve the cycle performance, and on the other hand, the prussian blue base consumes the residual lithium on the surface of the cathode material to reduce the residual alkali.
From the results of the embodiments 1 to 16 and the comparative examples 1 and2, it can be seen that the polyacrylonitrile and the prussian blue sodium containing material layer are coated on the surface of the high nickel material, so that the cycle retention rate is improved, and the residual alkali of the material is reduced.
When the W value of the precursor used is too high, the precursor has the phenomenon of metal segregation, and the Li/Ni mixed discharge of the synthesized positive electrode material is seriously deteriorated in rate performance.
The comparison between the embodiment 1 and the embodiment 3 shows that the precursor has an excessively large Q value, many oxygen vacancies in the precursor, low particle strength, structural collapse caused by the high-temperature growth process of the material, and low bonding strength of the primary particles of the synthesized cathode material, and poor cycle performance. Compared with the embodiment 4, the embodiment 1 has the advantages that the crystal lattice deviation of the C axis of the synthesized positive electrode material is too large due to the fact that the Q value is too low, the crystal expansion is serious in the battery circulation process, and the circulation performance is poor.
The comparison between the examples 1 and 5 shows that the precursor W is too low, mn element is segregated, and the Mn element which plays a role in supporting the layered material can cause local structural instability due to segregation, so that the particle strength is integrally deteriorated, and the cycle performance is deteriorated. As can be seen by comparing example 1 with example 6, the precursor W value is too high, a large amount of MnOOH exists in the precursor, weakly coordinated oxygen atoms exist in the anode material synthesized in the later period, and the overall structure of the anode material is damaged in the later period circulation process, so that the circulation performance is deteriorated.
Comparison of example 1 with example 7 shows that too low a concentration of acrylonitrile is difficult to act as a solidified metal during polymerization, resulting in poor cycle life. Comparing example 1 and example 8, it can be seen that too high concentration of acrylonitrile results in too much polyacrylonitrile cross-linking on the surface of the precursor, resulting in poor reactivity of lithium salt with the cobalt-free precursor, and thus resulting in poor overall rate and cycle performance of the synthesized cathode material.
As can be seen by comparing example 1 with example 9, T 1 If the temperature is too high, acrylonitrile cannot be decomposed as soon as it is polymerized to solidify metal ions, resulting in poor cycle performance. Comparison of example 1 and example 10 shows that T 1 If the temperature is too low, acrylonitrile is not polymerized, and cannot play a role in solidifying metal ions, and the cycle performance is deteriorated.
Comparing example 1 with example 11, it can be seen that the addition amount of sodium ferrocyanide is too low, and the in-situ prussian blue sodium generated on the surface of the cobalt-free cathode material is thin and uneven, thereby causing the cycle performance to be poor, and comparing example 1 with example 12, it can be seen that the addition amount of sodium ferrocyanide is too high, and the in-situ prussian blue sodium generated on the surface of the cobalt-free cathode material is too much, thereby causing the lithium ion transmission channel to be blocked, thereby causing the rate performance to be poor.
From examples 13 to 16, it can be seen that the rate performance is changed with the increase of the c-axis deviation, which is that a weak fault and metal ion dislocation exist in the layered positive electrode due to the increase of the lattice deviation, so that a transmission channel of the synthesized positive electrode is blocked in the charging and discharging process, and when the c-axis deviation exceeds 0.2 a, but the polymer layer is in the mass ratio range of 0.01% -0.5%, and the prussian blue material layer satisfies 150nm to 300nm, the cycle and rate performance can still be improved, which indicates that the polymer and the prussian blue coating layer can effectively slow down the structural shrinkage damage caused by the lattice deviation, so that the cycle stability and the rate performance are improved.
In the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.
The cobalt-free positive electrode material, the preparation method, the battery and the electric device provided in the embodiments of the present application are described in detail above, and specific examples are applied herein to explain the principles and embodiments of the present application, and the description of the embodiments is only used to help understand the method and the core concept of the present application; meanwhile, for those skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.

Claims (10)

1. A cobalt-free cathode material is characterized by comprising a high nickel material, wherein the surface of the high nickel material is provided with a polymer layer and a Prussian blue material layer, and the Prussian blue material layer is positioned on the surface of the polymer layer; the chemical formula of the high nickel material is Li x Ni y Mn 1-y O 2 Wherein x is more than or equal to 1 and less than or equal to 1.1, and y is more than or equal to 0.9 and less than or equal to 0.98; the thickness of the prussian blue material layer is 150 to 300nm; the polymer layer comprises polyacrylonitrile; the cobalt-free cathode material satisfies the following conditions: 0.01A is less than or equal to LD is less than or equal to 0.2A, wherein LD is c-axis lattice deviation.
2. The cobalt-free cathode material according to claim 1, wherein the polymer layer and the high nickel material are in mass percent: 0.05% -0.1%.
3. A method for preparing a cobalt-free positive electrode material according to claim 1, comprising the steps of:
preparing a high nickel material with a polymer layer;
and preparing a prussian blue material layer on the surface of the polymer layer.
4. The method for preparing a cobalt-free cathode material according to claim 3, wherein the high nickel material having a polymer layer is prepared by: taking a precursor Ni y Mn 1-y (OH) 2 Adding the polymer into a polymer monomer solution, stirring, drying, mixing with lithium salt, and sintering for the first time to obtain the high nickel material with a polymer layer.
5. The method for producing a cobalt-free positive electrode material according to claim 4,
the first sintering is divided into two-stage sinteringAnd (3) knot: the first stage sintering is as follows: heating to temperature T 1 Keeping the temperature for 3 to 6h 1 At 200-300 deg.C; the second stage sintering is as follows: from T 1 Heating to a temperature T 2 Keeping the temperature for 6 to 10 hours 2 The temperature is 650 ℃ to 750 ℃.
6. The method for preparing a cobalt-free cathode material according to claim 4, wherein the precursor Ni is Ni y Mn 1-y (OH) 2 The XRD of (A) satisfies: the D value is 2.5 to 3.5, the Q value is 0.5 to 2, the W value is 0.8 to 1.5, wherein the D value is the ratio of 001 characteristic peak strength to 100 characteristic peak strength, the Q value is the angle range occupied by the 001 characteristic peak half-peak width and the W value is the angle range occupied by the 100 characteristic peak half-peak width.
7. The method for preparing a cobalt-free cathode material according to claim 4, wherein the polymer monomer comprises acrylonitrile.
8. The method for preparing a cobalt-free cathode material according to claim 7, wherein the prussian blue-based material layer is prepared by: adding a high-nickel material with a polymer layer and sodium ferrocyanide into an acrylonitrile solution, stirring, filtering, and sintering for the second time to obtain a cobalt-free anode material;
the temperature of the second sintering is 200-300 ℃, and the heat preservation time is 6-10 h.
9. A battery comprising the cobalt-free positive electrode material according to any one of claims 1 to 2 or the cobalt-free positive electrode material prepared by the preparation method according to any one of claims 3 to 8.
10. An electric device comprising the battery according to claim 9.
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