CN115148970A - Olivine NaMPO 4 High-nickel-coated ternary or lithium-rich manganese-based positive electrode material and preparation method thereof - Google Patents

Olivine NaMPO 4 High-nickel-coated ternary or lithium-rich manganese-based positive electrode material and preparation method thereof Download PDF

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CN115148970A
CN115148970A CN202210815932.6A CN202210815932A CN115148970A CN 115148970 A CN115148970 A CN 115148970A CN 202210815932 A CN202210815932 A CN 202210815932A CN 115148970 A CN115148970 A CN 115148970A
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lithium
positive electrode
electrode material
nickel
manganese
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郑锋华
彭凡
潘齐常
王红强
李庆余
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Guangxi Normal University
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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
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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
    • H01M4/58—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
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes

Abstract

The method is simple and can effectively inhibit the problem of crystal lattice oxygen precipitation of the high-nickel ternary and lithium-rich manganese-based positive electrode material, fundamentally inhibit the crystal lattice oxygen precipitation and improve the structural stability of the high-nickel ternary and lithium-rich manganese-based positive electrode material.

Description

Olivine NaMPO 4 High-nickel-coated ternary or lithium-rich manganese-based positive electrode material and preparation method thereof
Technical Field
The invention relates to the technical field of preparation of electrode materials of lithium ion batteries, in particular to olivine NaMPO 4 (M = Ni, co and Mn) coated high-nickel ternary or lithium-rich manganese-based positive electrode material and a preparation method thereof.
Background
Due to the rapid increase of the global population and lifeThe level is continuously improved, the consumption speed of fossil energy is greatly increased, the emission of global greenhouse gases is rapidly increased due to the excessive use of the fossil energy, and people face unprecedented energy crisis and environmental pollution problems. The replacement of gasoline powered vehicles with electric automobiles is highly desirable and is already in progress. Therefore, one of the most basic and important scientific and technological efforts in the development of rechargeable batteries. Lithium ion batteries have revolutionized modern life as an energy storage device for portable electronic devices that are widely used in everyday life due to their high voltage and energy density, coupled with a long cycle life. However, to meet the demand of the electric automobile industry, future lithium ion batteries require higher energy density and better safety properties. The specific capacity of the anode material is a main determining factor of the energy density of the battery, so that the research and improvement of the anode material are the key points of the development of the lithium ion battery. At present, the commercialized anode materials mainly comprise lithium cobaltate, lithium manganate and lithium iron phosphate, which are limited by factors such as the practical lithium storage capacity limit of the anode materials, and are all below 200mAh/g, so that the requirement of high energy density of the power battery of the electric automobile is difficult to meet. Therefore, attention is focused on the high-nickel ternary positive electrode material and the lithium-rich manganese-based positive electrode material with high specific energy, the high-nickel ternary positive electrode material and the lithium-rich manganese-based positive electrode material have the characteristics of wide working voltage window, low cost, environmental protection, low toxicity and the like, and the energy density of the high-nickel ternary positive electrode material and the lithium-rich manganese-based positive electrode material is also higher than that of the traditional positive electrode material such as LiCoO 2 ,Li 2 Mn 2 O 4 And LiFePO 4 Equal in height.
The advantages of the high nickel ternary and lithium-rich manganese-based cathode materials are distinct from the numerous cathode materials and are paid much attention by the research community, but the existing problems of the materials are not negligible, and the high nickel ternary and lithium-rich manganese-based cathode materials mainly have two problems: (1) Performance degradation, (2) safety hazards, associated with the overall life of the battery, particularly in a fully charged state or at high temperatures, operating and storing. The causes of performance degradation are reported to include residual lithium compounds, oxygen evolution and synthesis reactions with electrolyte components, irreversible layered spinel-rock salt phase transitions, dissolution of excess metal ions, and microcracking of the secondary particle structure. While the actual mechanisms of battery failure are quite complex and may vary from case to case, all of the above mechanisms can ultimately be attributed to two essential properties of high nickel ternary and lithium rich manganese based positive electrode materials: (1) Residual lithium compounds and (2) oxygen loss, particularly due to thermodynamic instability of the H3 phase.
In view of the above problems, researchers have explored various ways to modify, of which coating on the surface of particles of high-nickel ternary and lithium-rich manganese-based positive electrode materials is one of the most effective ways, and therefore have developed various surface coatings to limit unnecessary structural degradation and prevent direct contact of the positive electrode material with the electrolyte. However, although cladding can increase the lattice oxygen evolution kinetic barrier by increasing the oxygen diffusion path, it is difficult to fundamentally solve the problem of lattice oxygen evolution at high pressure.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide olivine NaMPO 4 (M = Ni, co, mn) coated high-nickel ternary or lithium-rich manganese-based positive electrode material and a preparation method thereof. The method is simple and can effectively inhibit the problem of the crystal lattice oxygen precipitation of the high-nickel ternary and lithium-rich manganese-based positive electrode material, fundamentally inhibit the crystal lattice oxygen precipitation and improve the structural stability of the high-nickel ternary and lithium-rich manganese-based positive electrode material.
The technical scheme for realizing the purpose of the invention is as follows:
olivine NaMPO 4 (M = Ni, co, mn) coated high nickel ternary or lithium-rich manganese-based positive electrode material, the NaMPO 4 The coated high-nickel ternary or lithium-rich manganese-based positive electrode material is NaMPO 4 (M = Ni, co, mn) surface modified layered high-nickel ternary positive electrode material or lithium-rich manganese-based positive electrode material, naMPO 4 The mass of the (M = Ni, co and Mn) coating layer is 1% -10% of the mass of the layered high-nickel ternary or lithium-rich manganese-based positive electrode material, and the chemical formula of the layered high-nickel ternary positive electrode material is as follows: liNi x Co y M 1-x-y O 2 Wherein x is more than or equal to 0.6, and M is Mn or Al; the chemical formula of the layered lithium-rich manganese-based positive electrode material is as follows: li 1.2 Mn x Ni y Co 0.8-x-y O 2 Wherein x is more than or equal to 0.4 and less than or equal to 0.6, and y is more than or equal to 0.1 and less than or equal to 0.2.
Preparation of the above-described olivine NaMPO 4 The method for coating the high-nickel ternary or lithium-rich manganese-based positive electrode material (M = Ni, co and Mn) comprises the following steps:
1) Based on high nickel ternary positive electrode material LiNi x Co y M 1-x-y O 2 Wherein x is more than or equal to 0.6, and M is Mn or Al; or layered lithium-rich manganese-based cathode material Li 1.2 Mn x Ni y Co 0.8-x-y O 2 Wherein x is more than or equal to 0.4 and less than or equal to 0.6, y is more than or equal to 0.1 and less than or equal to 0.2, and nickel salt, cobalt salt and manganese salt are weighed according to the molar ratio of Ni, co and Mn elements;
2) Placing the nickel source, the cobalt source, the manganese source and the lithium salt weighed in the step 1) into a ball mill for ball milling for several hours;
3) Sintering the powder after ball milling and mixing in a tubular furnace, pre-sintering for 3-6 hours at 450-600 ℃, and then calcining for 10-16 hours at 750-950 ℃, wherein the calcining atmosphere is oxygen or air, so that a pure-phase layered high-nickel ternary positive electrode material or a lithium-rich manganese-based positive electrode material is obtained, wherein the molar ratio of the mixture to lithium salt is 1: 1.02-1: 1.08, and the excessive lithium salt is used for compensating the volatilization of a lithium source in the high-temperature calcining process;
4) After uniformly mixing a high-nickel ternary positive electrode material or a lithium-rich manganese-based positive electrode material in a ball mill at a high speed, introducing a coating material additive sodium source or nickel source or cobalt salt or manganese source or phosphorus source through low-speed mixing to obtain mixed powder;
5) Sintering the mixed powder obtained in the step 4) at 400-700 ℃ for 0.5-12 hours to obtain the olivine-structured NaMPO 4 The surface of the positive electrode is coated and modified with a high-nickel ternary positive electrode material or a lithium-rich manganese-based positive electrode material.
The nickel salt in the step 1) is one or more of nickel sulfate, nickel nitrate and nickel acetate; the cobalt salt is one or more of cobalt sulfate, cobalt nitrate and cobalt acetate; the manganese salt is one or more of manganese sulfate, manganese nitrate and manganese acetate.
The lithium salt in the step 2) is one or more of lithium hydroxide, lithium carbonate or lithium acetate.
The pre-sintering in the step 3) is carried out by heating to 450-600 ℃ at the heating rate of 1-10 ℃/min, keeping the temperature for 3-6 hours, then heating to 750-950 ℃ at the heating rate of 1-10 ℃/min, and keeping the temperature for 10-16 hours.
The sodium source of the coating additive in the step 4) is one or more of sodium nitrate, sodium sulfate, sodium carbonate, sodium chloride or sodium hydroxide; the nickel source is one or more of nickel sulfate, nickel nitrate or nickel acetate; the cobalt salt is one or more of cobalt sulfate, cobalt nitrate or cobalt nitrate; the manganese source is one or more of manganese sulfate, manganese nitrate or manganese acetate; the phosphorus source is one or more of ammonium dihydrogen phosphate, ammonium hydrogen phosphate or phosphoric acid.
The high speed in the step 4) is a mixing speed of 250 rpm-600 rpm; the low speed is a mixing speed of 50rpm to 200rpm.
The high-speed mixing time in the step 4) is 0.5-6 h; the time of the low-speed mixing is 0.5 h-2 h.
The sintering time in the step 5) is increased to 400-700 ℃ at the heating rate of 1-10 ℃/min, and the temperature is kept for 0.5-12 hours.
Compared with the prior art, the technical scheme has the advantages that the olivine NaMPO 4 The high-nickel ternary or lithium-rich manganese-based positive electrode material is coated by (M = Ni, co and Mn) to carry out surface modification, so that oxygen precipitation is fundamentally inhibited, and the structural stability of the high-nickel ternary or lithium-rich manganese-based positive electrode material is improved.
The method is simple and can effectively inhibit the problem of the evolution of the lattice oxygen of the high-nickel ternary and lithium-rich manganese-based anode material, fundamentally inhibit the precipitation of the lattice oxygen and improve the structural stability of the high-nickel ternary and lithium-rich manganese-based anode material.
Drawings
FIG. 1 is NaCoPO prepared in the examples 4 Coating a layered high-nickel ternary positive electrode material namely NCM811@ NCP and a pure-phase layered high-nickel ternary positive electrode material namely an XRD (X-ray diffraction) pattern before surface modification of NCM 811;
FIG. 2 shows NaCoPO prepared in example 4 SEM picture of the cladding layer-shaped high nickel ternary cathode material;
FIG. 3 is an SEM image of the pure-phase layered high-nickel ternary cathode material before surface modification in the examples;
FIG. 4 shows NaCoPO prepared in example 4 The discharge cycle curve diagram of the coated layered surface modified high-nickel ternary cathode material, namely NCM811@ NCP, and the pure-phase layered high-nickel ternary cathode material, namely NCM811, at the current density of 1.0C;
FIG. 5 shows NaMnPO prepared in example 4 The XRD patterns of the surface modified layered lithium-rich manganese-based positive electrode material LR-NCM @ NMP and the pure phase layered lithium-rich manganese-based positive electrode material LR-NCM before surface modification;
FIG. 6 shows NaMnPO prepared in example 4 SEM picture of the clad layered lithium-rich manganese-based anode material;
FIG. 7 is an SEM image of a pure-phase layered lithium-rich manganese-based positive electrode material before surface modification in an example;
FIG. 8 shows NaMnPO prepared in example 4 The discharge cycle curve chart of the coated layered surface modified lithium-rich manganese-based positive electrode material LR-NCM @ NMP and the pure-phase layered lithium-rich manganese-based positive electrode material LR-NCM under the current density of 1.0C.
Detailed Description
The invention will be further elucidated below by reference to the drawings and examples, without being limited thereto.
The embodiment is as follows:
example 1:
preparation of NaCoPO 4 The method for coating the layered high-nickel ternary cathode material comprises the following steps:
1) Nickel sulfate hexahydrate, cobalt sulfate heptahydrate and manganese sulfate monohydrate are mixed according to the chemical formula LiNi of a layered high-nickel ternary positive electrode material 0.8 Co 0.1 Mn 0.1 O 2 Ni shown in (1): co: mn =8:1:1, mixing lithium salt (the molar ratio of the precursor to the lithium salt is 1;
2) Sintering the powder subjected to ball milling in a tubular furnace, pre-sintering for 5 hours at 450 ℃, and then calcining for 15 hours at 750 ℃ in the atmosphere of oxygen to obtain a pure-phase layered high-nickel ternary cathode material;
3) After the high-nickel ternary positive electrode material is uniformly mixed at a high speed in a ball mill, coating material additives of sodium nitrate, cobalt nitrate and ammonium dihydrogen phosphate (a sodium source, a cobalt source and a phosphorus source are mixed at a low speed, wherein the molar ratio of the sodium source to the cobalt source to the phosphorus source is 1:1:1 addition);
4) The high-speed rotating speed in the ball mill in the step 3) is 450rpm, and the low-speed rotating speed is 50rpm;
5) The high-speed mixing time in the step 3) is 3 hours, and the low-speed mixing time is 1 hour;
6) Sintering the mixed powder obtained in the step 3) for 5 hours at 500 ℃ to obtain NaCoPO 4 And coating a sample of the layered high-nickel ternary cathode material.
In this example, the crystal phase was first investigated by XRD, and as shown in FIG. 1, it can be seen that there was no significant difference before coating, and that the diffraction peaks of all samples showed alpha-NaFeO with a space group of R-3m 2 Moreover, the additional diffraction peak not observed in NCM @ NCP, probably due to too low a content, was not detected, that is to say NaCoPO 4 The structure of the layered high-nickel ternary cathode material is not changed by coating, and the appearance before and after coating is characterized by NaCoPO through a field emission scanning electron microscope 4 SEM images of the surface-modified layered high-nickel ternary positive electrode material and the layered high-nickel ternary positive electrode material (before coating modification) are shown in FIGS. 2 and 3, and it can be known from the comparison between FIGS. 2 and 3 that NaCoPO 4 The treated layered high-nickel ternary cathode material can be seen to have a rougher and denser surface relative to the surface of the raw material under a high-power scanning electron microscope.
Preparation of the positive electrode material electrode sheet in this example: mixing an active material, a conductive agent (Super P: KS-6= 1) and a binder according to a mass ratio of 8:1:1, adding a proper amount of N-methyl pyrrolidone, uniformly stirring, uniformly coating the obtained slurry on an aluminum foil, vacuum-drying at 120 ℃, taking a metal lithium sheet as a negative electrode, and using Celgard2300 is a membrane and LiPF 6 Assembling the electrolyte in a glove box filled with argon to obtain a CR2025 type button experimental battery, and performing cycle performance test on the obtained battery at a multiplying power of 1.0C to obtain a cycle performance curve shown in FIG. 4, wherein as can be seen from FIG. 4, naCoPO 4 The coated samples exhibited excellent cycling stability and capacity retention, naCoPO 4 The initial discharge specific capacity of the modified raw material is 211.1mAh/g, which is obviously higher than that of a pure-phase layered high-nickel ternary positive electrode material by 191.7mAh/g, and after 200 cycles, the NaCoPO is performed 4 The capacity retention rate of the modified high-nickel ternary cathode material is 77.2% which is far greater than the capacity retention rate of the pure-phase high-nickel ternary cathode material of 51.3%, and the results show that the NaCoPO is adopted 4 The surface-modified layered high-nickel ternary cathode material has excellent comprehensive electrochemical performance.
Example 2:
preparation of NaCoPO 4 The method for coating the layered high-nickel ternary cathode material comprises the following steps:
1) First, ni (NO) was weighed separately 3 ) 2 ·6H 2 O、Co(NO 3 )2·6H 2 O、Mn(CH 3 COO) 2 ·4H 2 Molar ratio of O to NCM811 formula Ni: co: mn =8:1:1, weighing, and uniformly mixing the weighed substances and lithium salt (the molar ratio of the precursor to the lithium source is 1;
2) Sintering the powder subjected to ball milling in a tubular furnace at 500 ℃ for 5 hours, and then calcining at 800 ℃ for 10 hours in the presence of oxygen to obtain a pure-phase layered high-nickel ternary cathode material;
3) After the high-nickel ternary positive electrode material is uniformly mixed at high speed in a ball mill, a certain amount of coating material additives sodium carbonate, nickel acetate and ammonium dihydrogen phosphate (a sodium source, a cobalt source and phosphoric acid in a molar ratio of 1:1:1 addition);
4) The high-speed rotating speed in the ball mill in the step 3) is 350rpm, and the low-speed rotating speed is 75rpm;
5) In the step 3), the high-speed rotating speed time is 5 hours, and the low-speed rotating speed time is 0.5 hours;
6) Sintering the mixed powder obtained in the step 3), and presintering for 5 hours at 450 ℃ to obtain NaCoPO 4 Coating a layered high-nickel ternary cathode material.
Example 3:
preparation of NaCoPO 4 The method for coating the layered high-nickel ternary cathode material comprises the following steps:
1) Nickel acetate tetrahydrate, cobalt acetate tetrahydrate, manganese acetate tetrahydrate according to the ratio of Ni: co: mn =8:1: weighing at a molar ratio of 1; uniformly mixing the weighed substances and lithium salt (the molar ratio of the precursor to the lithium source is 1.05);
2) Placing the powder after ball milling and mixing in a tube furnace for sintering, presintering for 5 hours at 400 ℃, and then calcining for 12 hours at 750 ℃ in the atmosphere of oxygen to obtain a pure-phase high-nickel ternary cathode material;
3) After the high-nickel ternary positive electrode material is uniformly mixed in a ball mill at a high speed, a certain amount of coating material additives of sodium sulfate, nickel sulfate and ammonium dihydrogen phosphate (a sodium source, a cobalt source and phosphoric acid in a molar ratio of 1:1:1 addition);
4) The high-speed rotating speed in the ball mill in the step 3) is 550rpm, and the low-speed rotating speed is 100rpm;
5) In the step 3), the high-speed rotation time in the ball mill is 4h, and the low-speed rotation time is 1h;
6) Sintering the mixed powder obtained in the step 3) for 4 hours at 600 ℃ to obtain NaMnPO 4 The surface is modified with a high nickel ternary anode material.
Example 4:
preparation of NaMnPO 4 The method for coating the lithium-rich manganese-based positive electrode material comprises the following steps:
1) Manganese sulfate monohydrate, nickel sulfate hexahydrate and cobalt sulfate heptahydrate according to Li in the chemical formula of the layered lithium-rich manganese-based positive electrode material 1.2 Mn 0.6 Ni 0.1 Co 0.1 O 2 Mn shown in (A): ni: co =6:1:1, respectively weighing nickel salt, cobalt salt and manganese salt according to the molar ratio of 1, and mixing a certain amount of lithium saltPlacing the mixture in a ball mill and mixing uniformly;
2) Placing the powder after ball milling and mixing in a tubular furnace for sintering, and calcining for 10 hours at 850 ℃ in air atmosphere to obtain a pure-phase lithium-rich manganese-based positive electrode material;
3) After the lithium-rich manganese-based positive electrode material is uniformly mixed in a ball mill at a high speed, a certain amount of coating material additives, namely sodium acetate, manganese acetate and ammonium dihydrogen phosphate (a sodium source, a manganese source and a phosphorus source are mixed at a low speed according to a molar ratio of 1:1: 1. addition);
4) In the step 3), the high-speed rotating speed is 600rpm, and the low-speed rotating speed is 150rpm;
5) In the step 3), the high-speed rotating speed time is 6 hours, and the low-speed rotating speed time is 2 hours;
6) Sintering the mixed powder obtained in the step 3) at 600 ℃ for 2 hours to obtain NaMnPO 4 And coating the lithium-rich manganese-based positive electrode material.
As shown in FIG. 5, it can be seen from FIG. 5 that NaMnPO 4 The lithium-rich manganese-based anode material after surface modification is basically consistent with the pure-phase lithium-rich manganese-based anode material before modification, namely NaMnPO 4 The structure of the layered lithium-rich manganese-based cathode material is not changed by coating, two pairs of characteristic peaks of (006)/(102) and (108)/(110) are obviously split, and monoclinic phase Li appears in the range of 20-25 DEG 2 MnO 3 The superlattice structure shows that the sample can keep a lithium-rich layered structure with good crystallinity before and after coating, and simultaneously, the appearance before and after coating is characterized by a field emission scanning electron microscope, namely NaMnPO 4 SEM images of the surface-modified layered lithium-rich manganese-based positive electrode material and the layered lithium-rich manganese-based positive electrode material (before coating modification) are shown in fig. 6 and 7, and it can be seen from comparison between fig. 6 and 7 that NaMnPO 4 The layered lithium-rich manganese-based positive electrode material coated with the coating has the advantages that some fine particles are generated, the surface of the layered lithium-rich manganese-based positive electrode material is smoother, and the boundary is clear or different from that of the raw material nickel-rich manganese-based positive electrode material;
preparing an anode material electrode plate: mixing an active material, a conductive agent (Super P: KS-6= 1) and a binder according to a mass ratio of 8:1:1, adding a proper amount of N-methyl pyrrolidone, and uniformly stirringUniformly coating the obtained slurry on an aluminum foil, drying in vacuum at 120 ℃, taking a metal lithium sheet as a negative electrode, celgard 2300 as a diaphragm and LiPF 6 The electrolyte was assembled in a glove box filled with argon to obtain a CR2025 type button test cell, and the cell was subjected to a charge/discharge test at a rate of 1.0C, and the obtained cycle curve is shown in FIG. 8, from which it can be seen that NaMnPO prepared in this example is shown in FIG. 8 4 The initial specific discharge capacity of the surface-modified layered lithium-rich manganese-based positive electrode material is 215mAh/g, after 200 times of circulation, the specific discharge capacity is 183.2mAh/g, the circulation retention rate is about 85.2%, the initial specific discharge capacity of a battery made of the pure-phase layered lithium-rich manganese-based positive electrode material is 204mAh/g, after 200 times of circulation, the specific discharge capacity is 162.3mAh/g, the circulation retention rate is 79%, and the results show that the NaMnPO adopted 4 The surface-modified layered lithium-rich manganese-based positive electrode material has the advantages of stable structure, high specific capacity and good cycling stability.
Example 5:
1) According to the chemical formula of the layered lithium-rich manganese-based cathode material, li 1.2 Mn 0.58 Ni 0.18 Co 0.04 O 2 Ni shown in (1): co: respectively weighing nickel salt, cobalt salt and manganese salt according to the molar ratio of Mn = 0.18;
2) Placing the powder after ball milling and mixing in a tubular furnace for sintering, calcining for 5 hours at 450 ℃ in air atmosphere, and calcining for 16 hours at 900 ℃ to obtain a pure-phase lithium-rich manganese-based anode material;
3) After the lithium-rich manganese-based positive electrode material is uniformly mixed in a ball mill at a high speed, a certain amount of coating material additives, namely sodium acetate, nickel acetate and ammonium dihydrogen phosphate (a sodium source, a nickel source and a phosphorus source are mixed at a low speed according to a molar ratio of 1:1:1 addition);
4) Step 3), the high-speed rotating speed is 600rpm, and the low-speed rotating speed is 50rpm;
5) The high-speed rotating speed time of the step 3) is 6h, and the low-speed rotating speed time is 2h;
6) Sintering the mixed powder obtained in the step 3) for 5 hours at 300 ℃ to obtain the powderNaNiPO 4 And coating the lithium-rich manganese-based positive electrode material.

Claims (9)

1. Olivine NaMPO 4 (M = Ni, co, mn) coated high-nickel ternary or lithium-rich manganese-based positive electrode material, characterized in that the NaMPO 4 The coated high-nickel ternary or lithium-rich manganese-based positive electrode material is NaMPO 4 (M = Ni, co, mn) surface modified layered high-nickel ternary positive electrode material or lithium-rich manganese-based positive electrode material, naMPO 4 The mass of the (M = Ni, co and Mn) coating layer is 1% -10% of the mass of the layered high-nickel ternary or lithium-rich manganese-based positive electrode material, and the chemical formula of the layered high-nickel ternary positive electrode material is as follows: liNi x Co y M 1-x-y O 2 Wherein x is more than or equal to 0.6, and M is Mn or Al; the chemical formula of the layered lithium-rich manganese-based positive electrode material is as follows: li 1.2 Mn x Ni y Co 0.8-x-y O 2 Wherein x is more than or equal to 0.4 and less than or equal to 0.6, and y is more than or equal to 0.1 and less than or equal to 0.2.
2. A process for preparing the olivine NaMPO according to claim 1 4 The method for coating the high-nickel ternary or lithium-rich manganese-based positive electrode material (M = Ni, co and Mn) is characterized by comprising the following steps of:
1) Based on high nickel ternary positive electrode material LiNi x Co y M 1-x-y O 2 Wherein x is more than or equal to 0.6, and M is Mn or Al; or layered lithium-rich manganese-based cathode material Li 1.2 Mn x Ni y Co 0.8-x-y O 2 Wherein x is more than or equal to 0.4 and less than or equal to 0.6, y is more than or equal to 0.1 and less than or equal to 0.2, and nickel salt, cobalt salt and manganese salt are weighed according to the molar ratio of Ni, co and Mn elements;
2) Placing the nickel source, the cobalt source, the manganese source and the lithium salt weighed in the step 1) into a ball mill for ball milling for several hours;
3) Sintering the powder after ball milling and mixing in a tube furnace, pre-sintering for 3-6 hours at 450-600 ℃, and then calcining for 10-16 hours at 750-950 ℃ in oxygen or air atmosphere to obtain the pure-phase layered high-nickel ternary positive electrode material or the lithium-rich manganese-based positive electrode material, wherein the molar ratio of the mixture to the lithium salt is 1: 1.02-1: 1.08;
4) After uniformly mixing a high-nickel ternary positive electrode material or a lithium-rich manganese-based positive electrode material in a ball mill at a high speed, introducing a coating material additive sodium source or a nickel source or a cobalt salt or a manganese source or a phosphorus source through low-speed mixing to obtain mixed powder;
5) Sintering the mixed powder obtained in the step 4) at 400-700 ℃ for 0.5-12 hours to obtain the olivine-structure NaMPO 4 The surface of the positive electrode is coated and modified with a high-nickel ternary positive electrode material or a lithium-rich manganese-based positive electrode material.
3. The preparation method according to claim 2, wherein the nickel salt in step 1) is one or more of nickel sulfate, nickel nitrate and nickel acetate; the cobalt salt is one or more of cobalt sulfate, cobalt nitrate and cobalt acetate; the manganese salt is one or more of manganese sulfate, manganese nitrate and manganese acetate.
4. The preparation method of claim 2, wherein the lithium salt in step 2) is one or more of lithium hydroxide, lithium carbonate or lithium acetate.
5. The preparation method according to claim 2, wherein the pre-sintering in step 3) is performed by raising the temperature to 450-600 ℃ at a rate of 1-10 ℃/min, and maintaining the temperature for 3-6 hours, and then raising the temperature to 750-950 ℃ at a rate of 1-10 ℃/min, and maintaining the temperature for 10-16 hours during the calcination.
6. The preparation method of claim 2, wherein the sodium source of the coating additive in the step 4) is one or more of sodium nitrate, sodium sulfate, sodium carbonate, sodium chloride or sodium hydroxide; the nickel source is one or more of nickel sulfate, nickel nitrate or nickel acetate; the cobalt salt is one or more of cobalt sulfate, cobalt nitrate or cobalt nitrate; the manganese source is one or more of manganese sulfate, manganese nitrate or manganese acetate; the phosphorus source is one or more of ammonium dihydrogen phosphate, ammonium hydrogen phosphate or phosphoric acid.
7. The method according to claim 2, wherein the high-speed mixing speed in the step 4) is 250rpm to 600rpm; the low-speed mixing speed is 50rpm to 200rpm.
8. The method according to claim 2, wherein the high speed mixing time in step 4) is 0.5 to 6 hours; the time of the low-speed mixing is 0.5 h-2 h.
9. The method according to claim 2, wherein the sintering time in step 5) is increased to 400-700 ℃ at a temperature increase rate of 1-10 ℃/min, and the temperature is maintained for 0.5-12 hours.
CN202210815932.6A 2022-07-12 2022-07-12 Olivine NaMPO 4 High-nickel-coated ternary or lithium-rich manganese-based positive electrode material and preparation method thereof Pending CN115148970A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116936776A (en) * 2023-09-15 2023-10-24 宁德时代新能源科技股份有限公司 Positive electrode active material, pole piece, battery and electric equipment

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116936776A (en) * 2023-09-15 2023-10-24 宁德时代新能源科技股份有限公司 Positive electrode active material, pole piece, battery and electric equipment
CN116936776B (en) * 2023-09-15 2024-03-19 宁德时代新能源科技股份有限公司 Positive electrode active material, pole piece, battery and electric equipment

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