CN116093272A - Cobalt-free positive electrode material, positive plate comprising same and battery - Google Patents

Cobalt-free positive electrode material, positive plate comprising same and battery Download PDF

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Publication number
CN116093272A
CN116093272A CN202211358637.9A CN202211358637A CN116093272A CN 116093272 A CN116093272 A CN 116093272A CN 202211358637 A CN202211358637 A CN 202211358637A CN 116093272 A CN116093272 A CN 116093272A
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positive electrode
cobalt
electrode material
free
coating layer
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朱计划
叶孔强
曾家江
李素丽
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Zhuhai Cosmx Battery Co Ltd
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Zhuhai Cosmx Battery 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
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/16—Oxides
    • C30B29/22—Complex oxides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H01M4/13—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
    • H01M4/36—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
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • 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
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a cobalt-free positive electrode material, a positive plate comprising the cobalt-free positive electrode material and a battery. The cobalt-free positive electrode material comprises a matrix, a first coating layer and a second coating layer, whereinThe matrix comprises a metal having the chemical formula Li (Ni x Mn 1‑x M 1 y M 2 z )O 2 Is a material of (2); the first cladding layer comprises a metal having the chemical formula Li (MnM 1 y M 2 z ) 2 O 4 Is a material of (2); the second cladding layer comprises niobium tungsten oxide; wherein x is more than or equal to 0.6 and less than or equal to 0.9,0<y≤0.02，0<z≤0.02；M 1 And M 2 The same or different, and are independently selected from at least one of Al, mg, ti, zr, B, Y, W, sr, la, mo, nb, V. The coating structure comprises a protective inner layer (a first coating layer) with a spinel phase structure and an outer layer (a second coating layer) with excellent conductive performance, so that the dynamic performance of the battery can be improved while the effects of stabilizing the surface/interface structure and improving the cycle performance are achieved.

Description

Cobalt-free positive electrode material, positive plate comprising same and battery
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a cobalt-free positive electrode material, a positive plate comprising the cobalt-free positive electrode material and a battery.
Background
Since the commercialization of lithium ion batteries by sony corporation in 1991, lithium ion batteries have been widely used in the fields of consumer electronics and electric automobiles because of their excellent characteristics such as high energy density, long cycle life, and environmental friendliness.
The positive electrode material is used as an important component of a lithium ion battery, has great influence on the cost and performance of the lithium ion battery, and is a commercial ternary positive electrode material Li [ Ni ] x Co y Mn 1-x-y ]O 2 The (NCM) has the advantages of Gao Fangdian g capacity, high energy density and the like, and becomes a hot spot for research and development and application in the field of lithium ion battery anode materials. However, the increasing demand for ternary materials accelerates global cobalt reserve consumption, and cobalt supply chain tightening significantly increases cobalt prices. The adoption of the underestimated/cobalt-free positive electrode can obviously reduce the cost of the battery, needs to reduce the dependence on cobalt, meets the increasing requirement on lithium ion batteries, and the underestimated/cobalt-free positive electrode material with low cost becomes the main trend of the development of the future lithium battery industry.
Co in ternary materials 3+ The existence of the (C) can maintain better dynamic performance and multiplying power discharge capacity, and meanwhile, the cation mixing can be reduced, and the layered structure can be stabilized. The low content of cobalt in the layered positive electrode in the underestimated/cobalt-free positive electrode material reduces the electronic conductivity of the material, thereby reducing the rate capability and low temperature capability. The cobalt-free positive electrode material improves the energy density by increasing the nickel content of the system, however, strong negative correlation exists between the discharge capacity and the cycle stability, and the non-active Mn of the lithium removal structure is stabilized 4+ The reduced content causes a decrease in the cycle stability.
Cobalt-free materials currently developed are mostly polycrystalline materials, and the simultaneous occurrence of inter-and intra-crystalline cracks at high voltages exposes a large number of fresh surfaces inside the secondary particles. The activity of lattice oxygen on the outer layer of the primary particles after pulverization of the material is higher, and the oxygen release behavior is greatly aggravated, so that the structural stability is reduced and the capacity is reduced.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a cobalt-free positive electrode material, and a positive electrode plate and a battery comprising the cobalt-free positive electrode material. The cobalt-free positive electrode material has a stable surface/interface structure, and can obviously improve the rate performance, the cycle performance and the safety performance of the battery when being used in the battery.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
a cobalt-free positive electrode material comprises a matrix, a first coating layer and a second coating layer, wherein the matrix comprises a metal oxide having the chemical formula of Li (Ni x Mn 1-x M 1 y M 2 z )O 2 Is a material of (2); the first cladding layer comprises a metal having the chemical formula Li (MnM 1 y M 2 z ) 2 O 4 Is a material of (2); the second cladding layer comprises niobium tungsten oxide; wherein x is more than or equal to 0.6 and less than or equal to 0.9,0<y≤0.02，0<z≤0.02；M 1 And M 2 The same or different, and are independently selected from at least one of Al, mg, ti, zr, B, Y, W, sr, la, mo, nb, V.
According to the embodiment of the invention, the crystal structure of the cobalt-free positive electrode material is a single crystal structure, and the single crystal structure can solve the problem of repeated microcrack formation of the polycrystalline cobalt-free positive electrode material in the circulation process, and improve the circulation performance and the safety performance of the cobalt-free positive electrode material.
According to the embodiment of the invention, the first coating layer is coated on the surface of the substrate, and the coating is a full coating or a partial coating.
According to the embodiment of the invention, the second coating layer is coated on the outer surface of the first coating layer, and the coating is a full coating or a partial coating.
According to an embodiment of the invention, the niobium tungsten oxide has the formula Nb 18 W 16 O 93 Or Nb (Nb) 16 W 5 O 55 . The invention adopts a mode of coating the surface with the niobium tungsten oxide, is favorable for forming a first coating layer with a spinel phase structure and a second coating layer with a fast ion conductor property on the surface of the matrix, and improves the diffusion migration rate and the dynamic property of lithium ions of the cobalt-free anode material.
According to an embodiment of the invention, the niobium tungsten oxide has a median particle diameter of 50nm to 200nm, for example 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm or 200nm.
According to an embodiment of the present invention, the Li (Ni x Mn 1-x M 1 y M 2 z )O 2 Has a layered structure.
According to an embodiment of the invention, the Li (MnM 1 y M 2 z ) 2 O 4 Has a spinel phase structure. The invention adopts the method of coating Li (MnM) with spinel phase structure on the surface 1 y M 2 z ) 2 O 4 The material can stabilize the surface/interface structure of the anode material and improve the cycle performance of the battery. At the same time, the invention adopts co-doping (M 1 And M 2 ) The effect stabilizes the structural main body of the positive electrode material, and the high-valence cation doping can solve the problem of Li (Ni) caused by Li/Ni mixed discharge x Mn 1-x M 1 y M 2 z )O 2 The collapse problem of the layered structure, thereby improving the stability and long cycle performance of the layered structure.
According to an embodiment of the invention, the thickness of the first cladding layer is 5nm to 20nm, for example 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, 11nm, 12nm, 13nm, 14nm, 15nm, 16nm, 17nm, 18nm, 19nm or 20nm.
According to an embodiment of the present invention, the thickness of the second coating layer is 5nm to 10nm, for example, 5nm, 6nm, 7nm, 8nm, 9nm or 10nm.
According to an embodiment of the present invention, the first coating layer accounts for 0.02wt% to 2.5wt% of the total mass of the cobalt-free cathode material, for example, 0.02wt%, 0.03wt%, 0.05wt%, 0.08wt%, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1.0wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt%, 2.0wt%, 2.1wt%, 2.2wt%, 2.3wt%, 2.4wt% or 2.5wt%.
According to an embodiment of the present invention, the second coating layer accounts for 0.02wt% to 2.5wt% of the total mass of the cobalt-free cathode material, for example, 0.02wt%, 0.03wt%, 0.05wt%, 0.08wt%, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1.0wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt%, 2.0wt%, 2.1wt%, 2.2wt%, 2.3wt%, 2.4wt% or 2.5wt%.
According to an embodiment of the present invention, the cobalt-free positive electrode material has a median particle diameter of 2 μm to 5 μm.
The invention also provides a preparation method of the cobalt-free positive electrode material, which comprises the following steps:
(1) Ni is added with x Mn 1-x (OH) 2 Precursor, lithium salt and metal element M 1 Compound (iv) and metal element M-containing compound (iv) 2 Is mixed with the compound of (C) and is sintered for the first time to prepare the doped metal element M 1 And doped with goldGeneric element M 2 Li (Ni) x Mn 1- x M 1 y M 2 z )O 2 ；
(2) Nb is set to 2 O 5 And WO 3 The mixture is calcined and nano-processed in sequence to obtain the niobium tungsten oxide coating agent;
(3) Li (Ni) of step (1) x Mn 1-x M 1 y M 2 z )O 2 Mixing the powder with the niobium tungsten oxide coating agent in the step (2), and performing secondary sintering to obtain an intermediate;
(4) And (3) mixing the intermediate obtained in the step (3) with the niobium tungsten oxide coating agent obtained in the step (2), and performing third sintering to obtain the cobalt-free positive electrode material.
According to an embodiment of the present invention, in step (1), the Ni x Mn 1-x (OH) 2 The precursor is prepared by a coprecipitation method.
Illustratively, the Ni x Mn 1-x (OH) 2 The precursor is prepared by the following method:
mixing soluble nickel salt, soluble manganese salt and ammonia water, regulating the pH value of the reaction solution to 11.0-12.0, and performing coprecipitation reaction to prepare the Ni x Mn 1-x (OH) 2 A precursor.
Wherein the temperature of the coprecipitation reaction is 50-70 ℃ and the time is 30-50 h.
Wherein the mass concentration of the ammonia water is 10-18%.
Wherein Ni in the soluble nickel salt 2+ And soluble manganese salt Mn 2+ The molar ratio of (2) is x, 1-x.
Wherein the coprecipitation reaction is carried out under the protection of nitrogen gas.
According to an embodiment of the invention, in step (1), the lithium salt is selected from lithium carbonate and/or lithium hydroxide.
According to an embodiment of the present invention, in step (1), the metal element M is doped 1 And doping a metal element M 2 Is defined as above.
According to an embodiment of the present invention, in step (1), the metal element M is contained 1 Is selected from the group consisting of compounds containing a metal element M 1 Is an oxide of (a).
According to the embodiment of the invention, in the step (1), the temperature of the first sintering is 900-1200 ℃, the heat preservation time is 3-12 h, the heating rate during sintering is 2-5 ℃/min, and the atmosphere in the sintering process is pure oxygen atmosphere.
According to an embodiment of the present invention, in step (1), the Ni x Mn 1-x (OH) 2 Ni in precursor 2+ And Mn of 2+ Sum of molar contents of (2) and M containing a metal element 1 M in the compound of (C) 1 The molar ratio of (2) is 100 (0) and does not include 100:0.
According to an embodiment of the present invention, in step (1), the Ni x Mn 1-x (OH) 2 Ni in precursor 2+ And Mn of 2+ Sum of molar contents of (2) and M containing a metal element 2 M in the compound of (C) 2 The molar ratio of (2) is 100 (0) and does not include 100:0.
According to an embodiment of the present invention, in step (1), the Ni x Mn 1-x (OH) 2 Ni in precursor 2+ And Mn of 2+ Sum of molar contents of (2) and Li in lithium salt + The molar ratio of (1) to (0.96-1.10): 1.
According to an embodiment of the present invention, in step (2), nb 2 O 5 Nb and WO in 3 The molar ratio of W in (2) is 18:16 or 16:5.
According to an embodiment of the present invention, in the step (2), the calcination temperature is 1100 ℃ to 1300 ℃ and the time is 3h to 12h.
According to an embodiment of the present invention, in step (2), the nano-processing is a ball milling process.
According to an embodiment of the invention, in step (2), the median particle diameter of the niobium tungsten oxide coating agent is 50nm to 200nm, for example 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm or 200nm.
According to the embodiment of the invention, in the step (3), the temperature rising rate of the second sintering is 2-8 ℃/min, the temperature of the second sintering is 800-900 ℃, the time of the second sintering is 6-12 h, and the atmosphere of the second sintering is an oxygen-containing atmosphere.
According to an embodiment of the present invention, in step (3), li (Ni x Mn 1-x M 1 y M 2 z )O 2 The mass ratio of the niobium tungsten oxide coating agent to the niobium tungsten oxide coating agent in the step (2) is 1:0.5-1.5%.
According to the embodiment of the invention, in the step (3), the added niobium tungsten oxide coating agent is roasted at the temperature of 800-900 ℃, the niobium tungsten oxide can generate decomposition reaction, and the doped metal element M with the catalysis and lamellar structure 1 And doping a metal element M 2 Li (Ni) x Mn 1-x M 1 y M 2 z )O 2 Is formed into Li (MnM) having a spinel phase structure 1 y M 2 z ) 2 O 4 To maintain a more stable structure.
According to an embodiment of the present invention, in the step (4), the temperature rising rate of the third sintering is 2 ℃/min to 8 ℃/min, the temperature of the third sintering is 600 ℃ to 800 ℃, the time of the third sintering is 6h to 12h, and the atmosphere of the third sintering is an oxygen-containing atmosphere.
According to the embodiment of the invention, in the step (4), the mass ratio of the intermediate obtained in the step (3) to the niobium tungsten oxide coating agent obtained in the step (2) is 1:0.2% -0.6%.
According to an embodiment of the present invention, in the step (4), a niobium tungsten oxide coating agent is added and baked at a temperature of 600 to 800 ℃, so that a niobium tungsten oxide layer having a rapid ion conductor structure can be formed on the surface of the material.
The invention also provides a positive plate, which comprises the cobalt-free positive electrode material.
According to an embodiment of the present invention, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer coated on at least one side surface of the positive electrode current collector, the positive electrode active material layer including the cobalt-free positive electrode material described above.
According to an embodiment of the present invention, the positive electrode active material layer further includes a conductive agent. In some embodiments, the conductive agent is selected from one or more of conductive carbon black, acetylene black, ketjen black, carbon fiber, graphene, single-walled carbon nanotubes, multi-walled carbon nanotubes.
According to an embodiment of the present invention, the positive electrode active material layer further includes a binder. In some embodiments, the binder is selected from one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyethylene, polyvinyl alcohol, polyvinyl chloride, polyvinyl fluoride, polyvinylpyrrolidone, polytetrafluoroethylene, polypropylene, styrene-butadiene rubber, epoxy resin, butadiene-based rubber binder, acrylonitrile-based binder.
According to an embodiment of the present invention, the positive electrode active material layer comprises the following components in percentage by mass:
91 to 97.5 weight percent of cobalt-free positive electrode material, 0.5 to 4 weight percent of conductive agent and 2 to 5 weight percent of binder.
The invention also provides a battery, which comprises the cobalt-free positive electrode material; alternatively, the battery includes the positive electrode sheet described above.
According to an embodiment of the invention, the battery is a lithium ion battery.
On the one hand, the cobalt-free positive electrode material is easy to generate phase change and lattice oxygen loss under high voltage, and the lattice structure phase and the thermal stability are seriously deteriorated. The coating structure comprises a protective inner layer (a first coating layer) with a spinel phase structure and an outer layer (a second coating layer) with excellent conductive performance, so that the dynamic performance of the battery can be improved while the effects of stabilizing the surface/interface structure and improving the cycle performance are achieved. On the other hand, the cobalt-free positive electrode material can generate a series of side reactions with electrolyte under high voltage, the interface stability is poor, and the electrochemical properties such as the cycle stability, the high-temperature storage performance and the like are greatly influenced. The high-valence metal ions are adopted for doping, and the synergistic effect of multi-element doping can overcome the structural defect of the cobalt-free positive electrode material, so that the electrochemical performance of the cobalt-free positive electrode material can be improved from multiple aspects, and the discharge gram capacity and the cycle performance of the cobalt-free positive electrode material are improved.
The invention has the beneficial effects that:
the invention provides a cobalt-free positive electrode material, a positive electrode plate comprising the cobalt-free positive electrode material and a battery.
1. The invention is characterized in that the matrix material Li (Ni x Mn 1-x M 1 y M 2 z )O 2 Surface-coated niobium tungsten oxide with high ionic radius W 6+ And Nb (Nb) 5+ The interlayer spacing can be increased, and partial lithium vacancies and electron vacancies can be formed by the synergistic effect of three elements of Nb, W and O, so that the bulk conductivity and the grain boundary conductivity of the cobalt-free positive electrode material can be effectively improved; the existence of lithium vacancies can establish a smoother channel for the transmission of lithium ions, and can further improve the diffusion migration rate of lithium ions, thereby improving the rate capability of the cobalt-free positive electrode material.
2. The invention is characterized in that the matrix material Li (Ni x Mn 1-x M 1 y M 2 z )O 2 Surface-coated Li (MnM) having spinel phase structure 1 y M 2 z ) 2 O 4 Li (MnM) of the spinel phase structure 1 y M 2 z ) 2 O 4 The thermal stability and the structural stability of the cobalt-free positive electrode material can be improved, and the surface structure degradation phenomenon can be effectively inhibited; meanwhile, the direct contact between the cobalt-free positive electrode material and the electrolyte can be reduced, the interface stability is improved, the structural appearance of the cobalt-free positive electrode material is ensured to be complete, and the effects of stabilizing the surface/interface structure and improving the cycle performance are achieved.
3. The structure main body is stabilized by adopting the co-doping effect, and the introduction of high-valence ions causes charge compensation to occur in the positive electrode structure so as to generate holes, so that electrons can more easily transit from a valence band to a conduction band, and the electron conductivity and the lithium ion diffusion capability of the material are enhanced. The transition metal ion is doped and embedded into the cobalt-free positive electrode material to inhibit the phase transition of the deep lithium removal structure, so that the problem of collapse of the layered structure caused by Li/Ni mixed arrangement is solved, and the high-performance positive electrode material with stable structure is formed.
4. The single crystallization route, conventional polycrystalline materials inevitably suffer from inter-crystalline cracks and structural collapse of secondary spheres during the cycling, resulting in serious performance degradation. The cobalt-free positive electrode material has a single crystal structure, has fewer crystal boundaries and a complete crystal structure, can greatly inhibit inter-crystal cracks caused by anisotropic stress in a long-term circulation process and the conditions of positive electrode oxygen release and particle pulverization in the circulation process, and improves the circulation performance and the safety performance of the cobalt-free positive electrode material.
Drawings
FIG. 1 is an XRD pattern of a cobalt-free positive electrode material of example 1 of the present invention;
FIG. 2 is an SEM image of a cobalt-free positive electrode material of example 1 of the present invention;
FIG. 3 is test data of button cell assembled with cobalt-free positive electrode material of example 1 of the present invention;
FIG. 4 is a graph of 45℃cycle capacity retention of a lithium ion battery assembled with a cobalt-free positive electrode material of example 1 of the present invention;
fig. 5 is a schematic structural diagram of a cobalt-free positive electrode material of example 1 of the present invention.
Detailed Description
The present invention will be described in further detail with reference to specific examples. It is to be understood that the following examples are illustrative only and are not to be construed as limiting the scope of the invention. All techniques implemented based on the above description of the invention are intended to be included within the scope of the invention.
The experimental methods used in the following examples are all conventional methods unless otherwise specified; the reagents, materials, etc. used in the examples described below are commercially available unless otherwise specified.
Example 1
1. Preparation of cathode Material
1) Synthesizing Ni by coprecipitation method 0.65 Mn 0.35 (OH) 2 Precursor, niSO 4 、MnSO 4 And ammonia water according to a molar ratio n (Ni): n (Mn) =65:35 to obtain Ni 0.65 Mn 0.35 (OH) 2 A precursor; the reaction temperature is 50 ℃ and the reaction time is 36h; ammonia water is added to adjust the pH value of the reaction solution to 11.2, and nitrogen is continuously introduced into the reaction kettle; ni is added with 0.65 Mn 0.35 (OH) 2 Precursor and LiOH are mixed according to Ni 2+ And Mn of 2+ Sum of molar contents of (2) and Li + The ratio of the molar contents of (2) is the molar ratio (Ni 2+ +Mn 2+ ):Li + Mixing=1:1.02, ni 0.65 Mn 0.35 (OH) 2 Precursor, zrO 2 And TiO 2 In molar ratio (Ni 2+ +Mn 2+ ):Zr 2+ :Ti 2+ Mixing the materials in a ratio of (100:0.5:0.5), and sintering for the first time after mixing uniformly, wherein the sintering temperature is 1080 ℃ and the time is 4 hours; preparation of Li (Ni) 0.65 Mn 0.35 Ti 0.005 Zr 0.005 )O 2 ；
2) Nb is added in a molar ratio n (Nb): n (W) =18:16 2 O 5 And WO 3 After mixing, sintering and ball milling are sequentially carried out to obtain the niobium tungsten oxide coating agent Nb with the particle diameter of 80nm 18 W 16 O 93 The method comprises the steps of carrying out a first treatment on the surface of the Sintering temperature is 1200 ℃ and sintering time is 4 hours;
3) Li (Ni) 0.65 Mn 0.35 Ti 0.005 Zr 0.005 )O 2 And niobium tungsten oxide coating agent Nb 18 W 16 O 93 Uniformly mixing according to the mass ratio of 1:0.8%, and performing secondary sintering to obtain an intermediate; the sintering temperature is 860 ℃ and the sintering time is 8 hours; niobium tungsten oxide and Li (Ni) 0.65 Mn 0.35 Ti 0.005 Zr 0.005 )O 2 Acting together and decomposing at high temperature into Li (MnTi) 0.005 Zr 0.005 ) 2 O 4 An intermediate of the coating layer;
4) The intermediate and niobium tungsten oxide coating agent Nb obtained by the method 18 W 16 O 93 Uniformly mixing according to the mass ratio of 1:0.4%, and sintering for the third time to obtain the cobalt-free anode material; the sintering temperature is 680 ℃ and the sintering time is 8 hours.
2. And (3) assembling a button cell: uniformly mixing the cobalt-free anode material, the conductive agent and PVDF according to the mass ratio of 90:5:5, and dispersing by using an N-methyl pyrrolidone (NMP) solvent to form slurry; the slurry is uniformly coated on an aluminum foil sheet and dried for 12 hours at 80 ℃ to obtain a positive electrode sheet, and the dried positive electrode sheet is rolled and cut into a wafer and put into a glove box for standby. The wafer prepared above is used as positive electrode, metallic lithium is used as negative electrode, celgard 2400 (microporous polypropylene film) is used as diaphragm, and 1mol/L LiPF 6 + (EC: EMC: dmc=1:1:1) as electrolyte, a 2032 type button cell was assembled.
3. And (3) assembling a lithium ion battery:
(1) Preparation of positive plate
The positive electrode material, the binder, the conductive carbon black SP and the carbon nano tube CNT which are prepared by the method are mixed according to the weight ratio of 96:2:1.5:0.5, mixing, adding N-methyl pyrrolidone (NMP), stirring under the action of a vacuum stirrer to obtain a positive electrode slurry with uniform fluidity, and adding N-methyl pyrrolidone (NMP) in the process to adjust the solid content of the positive electrode slurry; uniformly coating the anode slurry on a 12um model aluminum foil, wherein the coating surface density is controlled at 15.0mg/cm <2 >; and baking the coated aluminum foil in 5 sections of baking ovens with different temperature gradients, rolling the baked pole piece twice, and slitting and ultra-welding the rolled pole piece to obtain the required positive pole piece.
(2) Preparation of negative plate
Graphite as a cathode active material, sodium carboxymethyl cellulose (CMC-Na) as a thickener, styrene butadiene rubber SBR as a binder and acetylene black SP as a conductive agent according to the weight ratio of 96.5:1.0:1.0:1.5, mixing, adding deionized water as a solvent, and obtaining negative electrode slurry under the action of a vacuum stirrer; uniformly coating the negative electrode slurry on a copper foil; and baking the coated copper foil in 3 sections of baking ovens with different temperature gradients, rolling the baked pole piece twice, and slitting and ultra-welding the rolled pole piece to obtain the required negative pole piece.
(3) Electrolyte preparation and separator preparation
The electrolyte adopts commercial electrolyte, and takes ethylene carbonate, propylene carbonate and diethyl carbonate as solvents according to the mass ratio of 1:1:1, and 1mol/L lithium hexafluorophosphate (LiPF 6 ) As lithium salt, film forming additive and high voltage additive are added into the components; the 7+3 mu m mixed coating diaphragm (substrate polypropylene film+PVDF)&Ceramic hybrid coating) as a barrier film.
(4) Preparation of lithium ion batteries
Sequentially stacking the prepared positive plate, the prepared isolating film and the prepared negative plate, and preparing a multi-lug type battery cell by switching a multi-layer aluminum foil of the positive electrode of the battery cell with an aluminum lug through an aluminum foil and switching a multi-layer copper foil of the negative electrode with a nickel lug through a copper foil; the two layers of isolating films wrap the negative electrode plate, the positive electrode plate is placed on the isolating film, the isolating film is ensured to be positioned between the positive electrode plate and the negative electrode plate to play a role in isolating and subsequently transmitting lithium ions, and then the bare cell without liquid injection is obtained through winding; and (3) heat-sealing the bare cell in a shell made of an aluminum plastic film, injecting electrolyte into the bare cell with the baked moisture value less than 200ppm, and performing the procedures of vacuum packaging, hot and cold molding, formation, shaping, sorting and the like to obtain the lithium ion battery.
Fig. 1 is an XRD pattern of the cobalt-free cathode material of example 1, and it can be seen from fig. 1 that the prepared solid solution material has no other hetero-phase in the structure, and belongs to a layered ternary cathode material pattern.
Fig. 2 is an SEM image of the cobalt-free cathode material of example 1, and it can be seen from fig. 2 that the prepared single crystal particles have a round and smooth surface, a good surface coating effect, and a median particle diameter of the cobalt-free cathode material is 2 μm to 5 μm.
Fig. 3 is test data of a button cell assembled with the cobalt-free positive electrode material of example 1, having a gram capacity of 196.2mAh/g at 0.1C, illustrating that the positive electrode material has a higher gram capacity.
FIG. 4 is a graph of 45℃cycle capacity retention of a lithium ion battery assembled with the cobalt-free positive electrode material of example 1; as can be seen from fig. 4, the capacity retention rate after 1000 cycles of the battery is 88.2%, which indicates that the positive electrode material has superior cycle performance.
Fig. 5 is a schematic structural diagram of the cobalt-free cathode material of example 1. As can be seen from fig. 5, the positive electrode material prepared in example 1 has a multilayer structure. Comprises a cobalt-free positive electrode material matrix, a protective inner layer (middle layer) with a spinel phase structure and an outer layer (outer layer) with excellent conductive performance.
Example 2
1. Preparation of cathode Material
1) Synthesizing Ni by coprecipitation method 0.7 Mn 0.3 (OH) 2 Precursor, niSO 4 、MnSO 4 And ammonia water according to a molar ratio n (Ni): n (Mn) =70:30 to obtain Ni 0.7 Mn 0.3 (OH) 2 A precursor; the reaction temperature is 65 ℃ and the reaction time is 48 hours; ammonia water is added to adjust the pH value of the reaction solution to 11.5, and nitrogen is continuously introduced into the reaction kettle; ni is added with 0.7 Mn 0.3 (OH) 2 Precursor and LiOH are mixed according to Ni 2+ And Mn of 2+ Sum of molar contents of (2) and Li + The ratio of the molar contents of (2) is the molar ratio (Ni 2+ +Mn 2+ ):Li + Mixing=1:1.05, ni 0.7 Mn 0.3 (OH) 2 Precursor, al 2 O 3 And ZrO(s) 2 In molar ratio (Ni 2+ +Mn 2+ ):Al 3+ :Zr 2+ Mixing the materials in a ratio of (100:0.6:0.5), and sintering for the first time after the materials are uniformly mixed, wherein the sintering temperature is 1050 ℃ and the sintering time is 6 hours; preparation of Li (Ni) 0.7 Mn 0.3 Al 0.006 Zr 0.005 )O 2 ；
2) Molar ratio n (Nb): n (W) =18:16, nb 2 O 5 And WO 3 After mixing, sintering, calcining and ball milling are sequentially carried out to obtain the niobium tungsten oxide coating agent Nb with the particle size of 75nm 18 W 16 O 93 The method comprises the steps of carrying out a first treatment on the surface of the Sintering temperature is 1250 ℃ and sintering time is 4 hours;
3) Li (Ni) 0.7 Mn 0.3 Al 0.006 Zr 0.005 )O 2 Coating with niobium tungsten oxideNb as an agent 18 W 16 O 93 Uniformly mixing according to the mass ratio of 1:0.75%, and performing secondary sintering to obtain an intermediate; the sintering temperature is 880 ℃ and the sintering time is 7 hours; niobium tungsten oxide and Li (Ni) 0.7 Mn 0.3 Al 0.006 Zr 0.005 )O 2 Acting together and decomposing into an intermediate with a spinel-phase structure coating at high temperature;
4) The intermediate and niobium tungsten oxide coating agent Nb obtained by the method 18 W 16 O 93 Uniformly mixing according to the mass ratio of 1:0.3%, and sintering for the third time to obtain the cobalt-free anode material; the sintering temperature is 700 ℃ and the sintering time is 8 hours.
2. And (3) assembling a button cell: the procedure is as in example 1.
3. And (3) assembling a lithium ion battery: the procedure is as in example 1.
Example 3
1. Preparation of cathode Material
1) Synthesizing Ni by coprecipitation method 0.75 Mn 0.25 (OH) 2 Precursor, niSO 4 、MnSO 4 And ammonia water according to a molar ratio n (Ni): n (Mn) =75:25 to obtain Ni 0.75 Mn 0.25 (OH) 2 A precursor; the reaction temperature is 60 ℃ and the reaction time is 42 hours; ammonia water is added to adjust the pH value of the reaction solution to 11.8, and nitrogen is continuously introduced into the reaction kettle; ni is added with 0.75 Mn 0.25 (OH) 2 Precursor and Li 2 CO 3 According to Ni 2+ And Mn of 2+ Sum of molar contents of (2) and Li + The ratio of the molar contents of (2) is the molar ratio (Ni 2+ +Mn 2+ ):Li + Mixing=1:1.05, ni 0.75 Mn 0.25 (OH) 2 Precursor, Y 2 O 3 And TiO 2 In molar ratio (Ni 2+ +Mn 2+ ):Y 3+ :Ti 2+ Mixing the materials in a ratio of (1) =100:0.5:0.4, and sintering for the first time after the mixture is uniformly mixed, wherein the sintering temperature is 1000 ℃ and the time is 8 hours; preparation of Li (Ni) 0.75 Mn 0.25 Y 0.005 Ti 0.004 )O 2 ；
2) Molar ratio n (Nb): n (W) =16:5, nb 2 O 5 And WO 3 After mixing, sintering, calcining and ball milling are sequentially carried out to obtain the niobium tungsten oxide coating agent Nb with the particle size of 100nm 16 W 5 O 55 The method comprises the steps of carrying out a first treatment on the surface of the Sintering temperature is 1200 ℃ and sintering time is 5 hours;
3) Li (Ni) 0.75 Mn 0.25 Y 0.005 Ti 0.004 )O 2 And niobium tungsten oxide coating agent Nb 16 W 5 O 55 Uniformly mixing according to the mass ratio of 1:1%, and performing secondary sintering to obtain an intermediate; the sintering temperature is 860 ℃ and the sintering time is 8 hours; niobium tungsten oxide and Li (Ni) 0.75 Mn 0.25 Y 0.005 Ti 0.004 )O 2 Acting together and decomposing into intermediate with spinel phase structure coating layer at high temperature;
4) The intermediate and niobium tungsten oxide coating agent Nb obtained by the method 16 W 5 O 55 Uniformly mixing according to the mass ratio of 1:0.5%, and sintering for the third time to obtain the cobalt-free anode material; the sintering temperature is 720 ℃ and the sintering time is 8 hours.
2. And (3) assembling a button cell: the procedure is as in example 1.
3. And (3) assembling a lithium ion battery: the procedure is as in example 1.
Example 4
1. Preparation of cathode Material
1) Synthesizing Ni by coprecipitation method 0.6 Mn 0.4 (OH) 2 Precursor, niSO 4 、MnSO 4 And ammonia water according to a molar ratio n (Ni): n (Mn) =60:40 to obtain Ni 0.6 Mn 0.4 (OH) 2 A precursor; the reaction temperature is 60 ℃ and the reaction time is 50 hours; ammonia water is added to adjust the pH value of the reaction solution to 11.0, and nitrogen is continuously introduced into the reaction kettle; ni is added with 0.6 Mn 0.4 (OH) 2 Precursor and LiOH are mixed according to Ni 2+ And Mn of 2+ Sum of molar contents of (2) and Li + The ratio of the molar contents of (2) is the molar ratio (Ni 2+ +Mn 2+ ):Li + Mix = 1:1.025, ni 0.6 Mn 0.4 (OH) 2 Precursor, WO 3 And ZrO(s) 2 In molar ratio (Ni 2+ +Mn 2+ ):W 3+ :Zr 2+ Mixing the materials in a ratio of (1) =100:0.5:0.5, and sintering for the first time after the mixture is uniformly mixed, wherein the sintering temperature is 1120 ℃ and the time is 4 hours; preparation of Li (Ni) 0.6 Mn 0.4 W 0.005 Zr 0.005 )O 2 ；
2) The molar ratio n (Nb): n (W) =16:5, nb 2 O 5 And WO 3 After mixing, sintering, calcining and ball milling are sequentially carried out to obtain the niobium tungsten oxide coating agent Nb with the particle size of 75nm 16 W 5 O 55 The method comprises the steps of carrying out a first treatment on the surface of the Sintering temperature is 1200 ℃ and sintering time is 5 hours;
3) Li (Ni) 0.6 Mn 0.4 W 0.005 Zr 0.005 )O 2 And niobium tungsten oxide coating agent Nb 16 W 5 O 55 Uniformly mixing according to the mass ratio of 1:0.8%, and performing secondary sintering to obtain an intermediate; the sintering temperature is 880 ℃ and the sintering time is 5 hours; niobium tungsten oxide and Li (Ni) 0.6 Mn 0.4 W 0.005 Zr 0.005 )O 2 Acting together and decomposing into intermediate with spinel phase structure coating layer at high temperature;
4) The intermediate and niobium tungsten oxide coating agent Nb obtained by the method 16 W 5 O 55 Uniformly mixing according to the mass ratio of 1:0.4%, and sintering for the third time to obtain the cobalt-free anode material; the sintering temperature is 720 ℃ and the sintering time is 8 hours.
2. And (3) assembling a button cell: the procedure is as in example 1.
3. And (3) assembling a lithium ion battery: the procedure is as in example 1.
Comparative example 1
1. Preparation of cathode Material
1) Synthesizing Ni by coprecipitation method 0.7 Mn 0.3 (OH) 2 Precursor, niSO 4 、MnSO 4 And ammonia water according to a molar ratio n (Ni): n (Mn) =70:30 to obtain Ni 0.7 Mn 0.3 (OH) 2 A precursor; the reaction temperature is 65 ℃ and the reaction time is 48 hours; ammonia water is added to adjust the pH value of the reaction solution to 11.5, and nitrogen is continuously introduced into the reaction kettle; will beNi 0.7 Mn 0.3 (OH) 2 Precursor and LiOH are mixed according to Ni 2+ And Mn of 2+ Sum of molar contents of (2) and Li + The ratio of the molar contents of (2) is the molar ratio (Ni 2+ +Mn 2+ ):Li + Mixing=1:1.02, ni 0.7 Mn 0.3 (OH) 2 Precursor, Y 2 O 3 And ZrO(s) 2 In molar ratio (Ni 2+ +Mn 2+ ):Y 3+ :Ti 2+ Mixing the materials in a ratio of (100:0.6:0.5), and sintering for the first time after the materials are uniformly mixed, wherein the sintering temperature is 1080 ℃ and the time is 6 hours; preparation of Li (Ni) 0.7 Mn 0.3 Y 0.006 Zr 0.005 )O 2 ；
2) Li (Ni) 0.7 Mn 0.3 Y 0.006 Zr 0.005 )O 2 With Al 2 O 3 Uniformly mixing the coating agent according to the mass ratio of 1:0.3%, and performing third sintering to obtain the cobalt-free anode material; the sintering temperature is 720 ℃ and the sintering time is 8 hours.
2. And (3) assembling a button cell: the procedure is as in example 1.
3. And (3) assembling a lithium ion battery: the procedure is as in example 1.
Test case
a. Discharge gram capacity test:
the button cells of examples and comparative examples were subjected to a charge performance test at a temperature of 25.+ -. 5 ℃ as follows:
1) Activating the button cell for 24 hours;
2) Constant current charging is carried out to 4.45V at 0.1C, and the cut-off current is 0.05C;
3) Rest for 10 min;
4) The 0.1C constant current discharges to a lower voltage of 2.8V.
The discharge gram capacity of the positive electrode material was obtained by calculation, and the results are shown in table 1.
b. Multiplying power test (25 ℃, 2C/0.33C):
the lithium ion batteries of the examples and the comparative examples were subjected to rate performance test at a temperature of 25.+ -. 2 ℃ as follows:
1) Performing capacity test by cycling at 0.2C/0.2C for three times in the environment of 25+/-2 ℃;
2) 0.5C discharges to a lower voltage limit (2.8V);
3) Standing for 30min;
4) Constant-current charging to upper limit voltage (4.4V) at 0.5C, constant-voltage charging, and cutting off current at 0.05C;
5) Standing for 30min;
6) nC discharges to a lower voltage limit, where nc=0.2C/0.33C/0.5C/0.7C/1C/1.5C/2C/3C/5C;
7) And (3) repeating the steps 3-6 to finish the discharge steps of all multiplying powers.
The rate performance (rate=2c discharge capacity/0.33C discharge capacity) of the battery was obtained by calculation, and the results are shown in table 1.
c. Cycle capacity test
The lithium ion batteries of examples and comparative examples were subjected to cycle performance tests at temperatures of 25.+ -. 2 ℃ and 45.+ -. 2 ℃ respectively, and the test procedures included:
1) The battery core is arranged in an environment of 25+/-2 ℃ (45+/-2 ℃);
2) Discharging 0.5C to lower limit voltage (2.8V), and standing for 30min;
3) 1C is charged to an upper limit voltage (4.4V), and 0.05C is cut off;
4) Standing for 30min;
5) 1C discharges to a lower limit voltage (2.8V); standing for 30min;
6) 1C is charged to an upper limit voltage (4.4V), 0.05C is cut off, and the mixture is kept stand for 30min;
repeating the cycle of 5-6 steps for 1000 times.
Capacity retention formula: the first cycle test capacity is designated as A1, and after 1000 cycles, the test capacity is designated as A2; capacity retention = A2/a1×100%, and specific test results are shown in table 1.
d. Low temperature Performance test (-20 ℃/25 ℃ C.)
And testing the state voltage, internal resistance and thickness of the lithium ion battery at 25+/-2 ℃.
1) Standing at 25+ -2deg.C for 30min;
2) 0.5C is discharged to a lower limit voltage of 2.8V;
3) Standing for 4h;
4) 1C is charged to an upper limit voltage of 4.4V, and the cut-off current is 0.05C;
5) Standing for 4h;
6) An incubator environment, in which the mixture is kept stand for 4 hours at different temperatures (25 ℃/45 ℃/0 ℃/-10 ℃/-20 ℃), and then discharged to a lower limit voltage of 2.8V at 1 ℃;
7) Standing for 4 hours at 25+/-2 ℃;
repeating the steps 4-7 until all the temperature discharge tests are completed.
The rate performance (rate= -20 ℃ discharge capacity/25 ℃ discharge capacity) of the battery was obtained by calculation, and the results are shown in table 1.
e. Thermal decomposition temperature test-DSC test
Lithium ion cells were fully charged to 4.4V at 0.33C magnification and disassembled in an argon filled glove box to recover the positive electrode tab, and the tab was rinsed with dimethyl carbonate (DMC) and dried. The positive electrode plate and electrolyte are placed in a high-pressure crucible of a thermal analysis instrument together, and 1mol/L LiPF is adopted 6 (EC: DMC: dmc=1:1:1) as electrolyte, wherein the positive electrode sheet and the electrolyte are added in an amount of 1mg:0.6 mu L is prepared, the thermal analysis testing temperature range is 25-500 ℃, and the heating rate is 5 ℃/min.
Table 1 battery performance of examples 1-4 and comparative example 1
Figure BDA0003921372590000161
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A cobalt-free positive electrode material is characterized by comprising a substrate, a first coating layer and a second coating layer, wherein the substrate comprises a metal oxide having the chemical formula Li (Ni x Mn 1-x M 1 y M 2 z )O 2 Is a material of (2); the first cladding layer comprises a metal having the chemical formula Li (MnM 1 y M 2 z ) 2 O 4 Is a material of (2); the second cladding layer comprises niobium tungsten oxide; wherein x is more than or equal to 0.6 and less than or equal to 0.9,0<y≤0.02，0<z≤0.02；M 1 And M 2 The same or different, and are independently selected from at least one of Al, mg, ti, zr, B, Y, W, sr, la, mo, nb, V.
2. The cobalt-free positive electrode material according to claim 1, wherein the crystal structure of the cobalt-free positive electrode material is a single crystal structure.
3. The cobalt-free positive electrode material according to claim 1 or 2, wherein the first coating layer is coated on the surface of the substrate, the second coating layer is coated on the outer surface of the first coating layer, and the coating is a full coating or a partial coating.
4. The cobalt-free positive electrode material according to claim 1, wherein the niobium tungsten oxide has a chemical formula of Nb 18 W 16 O 93 Or Nb (Nb) 16 W 5 O 55 ；
And/or the median particle diameter of the niobium tungsten oxide is 50 nm-200 nm.
5. The cobalt-free positive electrode material according to claim 1, wherein the Li (Ni x Mn 1-x M 1 y M 2 z )O 2 Has a layered structure;
and/or, the Li (MnM) 1 y M 2 z ) 2 O 4 Has a spinel phase structure.
6. The cobalt-free positive electrode material according to claim 1, wherein the thickness of the first coating layer is 5nm to 20nm;
and/or the thickness of the second coating layer is 5 nm-10 nm.
7. The cobalt-free positive electrode material according to claim 1 or 6, wherein the mass of the first coating layer is 0.02wt% to 2.5wt% of the total mass of the cobalt-free positive electrode material;
and/or the mass of the second coating layer accounts for 0.02-2.5 wt% of the total mass of the cobalt-free positive electrode material.
8. A positive electrode sheet, characterized in that the positive electrode sheet comprises the cobalt-free positive electrode material according to any one of claims 1 to 7.
9. The positive electrode sheet according to claim 8, wherein the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer coated on at least one side surface of the positive electrode current collector, the positive electrode active material layer comprising the cobalt-free positive electrode material according to any one of claims 1 to 7.
10. A battery comprising the cobalt-free positive electrode material of any one of claims 1-7; alternatively, the battery includes the positive electrode sheet according to claim 8 or 9.
CN202211358637.9A 2022-11-01 2022-11-01 Cobalt-free positive electrode material, positive plate comprising same and battery Pending CN116093272A (en)

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