CN113571705A - Cathode material, preparation method thereof and lithium ion battery - Google Patents

Cathode material, preparation method thereof and lithium ion battery Download PDF

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Publication number
CN113571705A
CN113571705A CN202110738196.4A CN202110738196A CN113571705A CN 113571705 A CN113571705 A CN 113571705A CN 202110738196 A CN202110738196 A CN 202110738196A CN 113571705 A CN113571705 A CN 113571705A
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lithium
positive electrode
phosphate
electrode material
vanadium
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何向明
王莉
胡乔
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Beijing Huaruixin Dynamic Power Technology Development Co ltd
Tsinghua University
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Beijing Huaruixin Dynamic Power Technology Development Co ltd
Tsinghua University
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Priority to PCT/CN2022/099358 priority patent/WO2023273917A1/en
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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
    • H01M4/58—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
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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

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Abstract

The invention relates to a positive electrode material which comprises the main component of lithium manganese iron phosphate LiMn0.7Fe0.3PO4And lithium vanadium phosphate Li3V2(PO4)3And the substrate is coated with graphene. The invention also relates to a preparation method of the cathode material. The invention further relates to a lithium ion battery comprising the cathode material.

Description

Cathode material, preparation method thereof and lithium ion battery
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a positive electrode material, a preparation method thereof and a lithium ion battery.
Background
Lithium ion batteries have been widely used in the life of people as a new and important energy source. Since Goodenough et al proposed lithium cobalt oxide (LiCoO) in 19802) As a cathode material of a lithium ion battery, many new cathode materials of lithium ion batteries, such as lithium iron phosphate (LiFePO) were introduced after the lithium ion battery was commercialized by Sony corporation in 19904) Lithium nickelate (LiNiO)2) Lithium manganate (LiMnO)2) Lithium vanadium phosphate (Li)3V2(PO4)3) And the like. Lithium iron phosphate has received great attention and has attracted extensive research and rapid development due to its wide source of raw materials, lower cost and no environmental pollution, however, LiFePO4Has a low voltage plateau (3.4V, vs. Li/Li)+) Compared with LiFePO4，LiMnPO4With LiFePO4Has similar structure, also has the advantages of environmental protection, good compatibility with electrolyte and the like, and LiMnPO4Has 4.0V (vs. Li/Li)+) The energy density of the high voltage platform can be improved by about 20%. However, LiMnPO4Compared to LiFePO4Is one order of magnitude lower, and LiMnPO is generated during charging and discharging4/MnPO4The Taylor effect of ginger and Mn exist between2+Dissolution in electrolyte and the like, all make LiMnPO4The structure is destroyed and it is difficult to obtain excellent cycling and rate performance.
At present, for LiMnPO4Carrying out partial Fe2+The method for replacing the formation of lithium manganese iron phosphate becomes a mainstream method in the market, the material has the advantages of high energy density and stable circulation, however, the conductivity of the lithium manganese iron phosphate is still low, the reversible specific capacity of the lithium manganese iron phosphate under the high current density is limited, and the market demand is difficult to meet.
Disclosure of Invention
Based on this, there is a need for a positive electrode material capable of having higher conductivity, a method of preparing the same, and a lithium ion battery.
In one aspect of the invention, the invention provides a positive electrode material which comprises lithium manganese iron phosphate LiMn as a main component0.7Fe0.3PO4And lithium vanadium phosphate Li3V2(PO4)3And the substrate is coated with graphene.
In one embodiment, the mass ratio of the lithium vanadium phosphate to the lithium manganese iron phosphate is x (1-x), wherein x is more than 0 and less than or equal to 0.3.
In one embodiment, the graphene is present in an amount of 2 to 3 wt% based on the total weight of the cathode material.
In one embodiment, the positive electrode material is an ellipsoid-like particle having a size of 100nm to 150 nm.
In another aspect of the present invention, a method for preparing the cathode material is provided, which comprises the following steps:
mixing a lithium source, a vanadium source, a phosphorus source and a first carbon source according to a preset ratio to obtain a precursor of the lithium vanadium phosphate;
sintering the precursor of the lithium vanadium phosphate in an inert atmosphere to obtain lithium vanadium phosphate pre-sintered powder;
mixing the lithium vanadium phosphate pre-firing powder, the precursor of the lithium ferric manganese phosphate and a second carbon source according to a preset ratio to obtain a precursor of a positive electrode material;
and sintering the precursor of the positive electrode material in an inert atmosphere to obtain the positive electrode material.
In one embodiment, the lithium source is at least one of lithium dihydrogen phosphate, lithium nitrate, lithium acetate, and lithium hydroxide.
In one embodiment, the vanadium source is one or more of vanadium pentoxide, vanadium trioxide, vanadium dioxide and ammonium metavanadate.
In one embodiment, the phosphorus source is at least one of ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, phosphoric acid.
In one embodiment, the first carbon source is a carbon-containing compound, and the carbon-containing compound includes one or more of saccharides, organic acids, organic acid vinegar, small molecular alcohols, and other carbon-containing high molecular compounds.
In one embodiment, the second carbon source is one or more of glucose, polyvinyl alcohol, polyallyl alcohol, and polybutyl alcohol.
In one embodiment, the sintering temperature is 300-400 ℃ and the sintering time is 4-6 hours when sintering the precursor of lithium vanadium phosphate.
In one embodiment, the sintering temperature is 650 to 800 ℃ and the sintering time is 8 to 16 hours when the positive electrode precursor is sintered.
In another aspect of the invention, a lithium ion battery is provided, wherein the positive electrode comprises the positive electrode material.
Compared with the prior art, the invention has the following beneficial effects:
according to the positive electrode material provided by the invention, lithium manganese phosphate and lithium vanadium phosphate are used as matrixes, graphene is coated outside the matrixes in situ, and the lithium manganese phosphate, the lithium vanadium phosphate and the graphene have a synergistic effect, so that the conductivity of electrons and ions of the positive electrode material in the charging and discharging processes is effectively improved, and the positive electrode material has more excellent high rate performance and cycle stability.
Drawings
FIG. 1 is an XRD pattern of the positive electrode materials provided in examples 1-3 and comparative example 1;
FIG. 2 is an SEM image and an EDS element distribution diagram of the cathode materials provided in examples 1-3 and comparative example 1;
fig. 3 is a TEM image of the positive electrode materials provided in example 2 and comparative example 1;
fig. 4 is a first charge-discharge curve of the battery composed of the positive electrode materials provided in examples 1 to 3 and comparative example 1, where in fig. 4, the curves are x is 0, x is 0.05, x is 0.1, and x is 0.3 in the order indicated by the arrows;
FIG. 5 is a cycle performance test curve of the batteries composed of the positive electrode materials provided in examples 1 to 3 and comparative example 1;
fig. 6 is a rate performance test curve of batteries composed of the positive electrode materials provided in examples 1 to 3 and comparative example 1.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
The term "particle size" refers to the size of the smallest opening through which a particle can pass in the most favorable attitude.
The embodiment of the invention provides a positive electrode material which comprises the main component of lithium manganese iron phosphate LiMn0.7Fe0.3PO4And lithium vanadium phosphate Li3V2(PO4)3And the substrate is coated with graphene.
According to the positive electrode material provided by the embodiment of the invention, lithium manganese phosphate and lithium vanadium phosphate are used as substrates, and graphene is coated outside the substrates, so that the lithium manganese phosphate, the lithium vanadium phosphate and the graphene have a synergistic effect, the electronic and ionic conductivity of the positive electrode material in the charging and discharging processes is effectively improved, and the positive electrode material has more excellent high-rate performance and cycle stability under high voltage.
The lithium ferric manganese phosphate particles are basically ellipsoidal, the size range of the particles is 100 nm-150 nm, and the lithium vanadium phosphate particles are in irregular shapes. It is understood that the lithium ferric manganese phosphate and lithium vanadium phosphate can also be spherical, rhombohedral, or other shapes that resemble ellipsoids. Lithium manganese phosphate and lithium vanadium phosphate are used as matrixes, and folded graphene is uniformly coated on lithium manganese phosphate LiMn0.7Fe0.3PO4And lithium vanadium phosphate Li3V2(PO4)3The above.
In some preferred embodiments, the mass ratio of the lithium vanadium phosphate to the lithium manganese iron phosphate is x (1-x), wherein x is more than 0 and less than or equal to 0.3, and x can be 0.05, 0.1, 0.15, 0.2, 0.25 or 0.3.
In some embodiments, the content of the graphene is anywhere between 2 wt% and 3 wt%, and may also be, for example, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.4 wt%, 2.5 wt%, 2.6 wt%, 2.7 wt%, 2.8 wt%, 2.9 wt%, based on the total weight of the cathode material.
In another aspect of the present invention, a method for preparing the above cathode material is also provided, which comprises the following steps:
s10, mixing a lithium source, a vanadium source, a phosphorus source and a first carbon source according to a preset ratio to obtain a precursor of the lithium vanadium phosphate;
s20, sintering the precursor of the lithium vanadium phosphate in an inert atmosphere to obtain lithium vanadium phosphate pre-sintered powder;
s30, mixing the lithium vanadium phosphate pre-firing powder, the lithium manganese iron phosphate precursor and a second carbon source according to a preset ratio to obtain a positive electrode material precursor; and
and S40, sintering the precursor of the positive electrode material in an inert atmosphere to obtain the positive electrode material.
In step S10, the lithium source may include, but is not limited to, at least one of lithium dihydrogen phosphate, lithium nitrate, lithium acetate, and lithium hydroxide, preferably lithium acetate.
The vanadium source may include, but is not limited to, one or more of vanadium pentoxide, vanadium trioxide, vanadium dioxide and ammonium metavanadate, preferably ammonium metavanadate.
The phosphorus source may include, but is not limited to, one or more of vanadium pentoxide, vanadium trioxide, vanadium dioxide, and ammonium metavanadate, preferably ammonium dihydrogen phosphate or diammonium hydrogen phosphate.
The first carbon source acts as a reducing agent to reduce pentavalent vanadium to trivalent vanadium. The first carbon source may be selected from carbon-containing compounds, and may include, but is not limited to, one or more of sugars, organic acids, organic acid esters, small molecule alcohols, and other carbon-containing high molecule compounds. The saccharide can be selected from reducing carbon such as glucose and sucrose.
The molar ratio of the lithium source, the vanadium source and the phosphorus source may be (2.9-3.3): 2: (2.9-3.3). In some preferred embodiments, the molar ratio of the lithium source, vanadium source, and phosphorus source is 3:2: 3.
The amount of the first carbon source may be any value between 5 wt% and 20 wt% of the total weight of the lithium vanadium phosphate precursor, and may also be, for example, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, and 19 wt%.
The manner of mixing the lithium source, vanadium source, phosphorus source and first carbon source may be mechanical stirring or ball milling. Wherein, the ball milling equipment can be a stirring ball mill, a sand mill, a colloid mill, a jet mill, an impact type micro-powder ball mill, a jet vortex micro-powder mill, an impact type pulverizer or a rod type mechanical pulverizer. The ball milling tank and the milling balls are made of stainless steel, corundum, zirconia or agate. The rotation speed of ball milling and mixing can be 200 r/min-500 r/min, and the ball milling time can be 0.5-12 hours.
The ball milling can adopt dry ball milling or wet ball milling. In order to ensure that the raw materials can be uniformly mixed, wet ball milling is preferably adopted. Accordingly, the solvent used in the ball milling may be selected from organic or inorganic solvents, such as acetone or other solvents of low polarity, which are selected to be non-reactive with any of the starting materials but to provide an environment in which the starting materials react with each other. Preferably, acetone is used, and the requirements of safety and cost are met.
In step S20, when sintering the precursor of lithium vanadium phosphate, the sintering temperature may be 300 ℃ to 400 ℃, and the sintering time may be 4 hours to 6 hours.
The inert atmosphere may be at least one of oxygen, nitrogen, argon-hydrogen mixture gas. Preferably, the inert atmosphere is nitrogen.
In step S30, the precursor of lithium manganese iron phosphate can be obtained by any commercially available or known method for preparing a precursor of lithium manganese iron phosphate, including, but not limited to, a high-temperature solid-phase method, a carbothermic method, a sol-gel method, and the like.
In some embodiments, the precursor of lithium manganese iron phosphate comprises a main phase lithium manganese iron phosphate of the chemical formula LiMn and other impurities0.7Fe0.3PO4. Other impurities in the process of burningThe junction can be removed.
And the second carbon source is used for producing graphene in situ under the catalytic action of vanadium oxide in the lithium vanadium phosphate pre-firing powder. The second carbon source may be an organic carbon source, such as one or more of glucose, polyvinyl alcohol, polyallyl alcohol, and polybutyl alcohol. The amount of the second carbon source used may be 6 wt% to 10 wt% of the total weight of the positive electrode material precursor.
The method for mixing the lithium vanadium phosphate pre-firing powder, the lithium manganese iron phosphate precursor and the second carbon source can also be mechanical stirring or ball milling. The mixing method of the lithium source, the vanadium source, the phosphorus source and the first carbon source is substantially the same, and is not repeated herein. When the lithium vanadium phosphate pre-firing powder, the lithium manganese iron phosphate precursor, and the second carbon source are subjected to wet ball milling, the solvent used is preferably absolute ethanol.
In step S40, when the positive electrode precursor is sintered, the sintering temperature is 650 to 800 ℃, and the sintering time is 8 to 16 hours.
The inert atmosphere may be at least one of oxygen, nitrogen, argon-hydrogen mixture gas. Preferably, the inert atmosphere is nitrogen.
And cooling the sintered anode material in an inert atmosphere to obtain the anode material.
In the high-temperature heating process, the second carbon source generates folded graphene in situ under the catalytic action of vanadium oxide in lithium vanadium phosphate, and the folded graphene is coated on the surfaces of lithium iron phosphate and lithium vanadium phosphate particles, so that a stable anode material is formed.
In another aspect of the present invention, a lithium ion battery is further provided, which includes a positive electrode, a negative electrode, an electrolyte and the separator. The lithium ion battery of the present invention may be prepared and used according to a conventional method known in the art. The preparation method of the lithium ion battery of the invention is specifically described as follows.
(1) Positive electrode
The preparation method of the positive electrode can be as follows: a positive electrode current collector is coated with a positive electrode slurry including a positive electrode active material, a binder, a conductive agent, and a solvent, and then the coated positive electrode current collector is dried and rolled.
The positive electrode current collector is not particularly limited as long as it has conductivity without causing adverse chemical changes in the battery, and for example, stainless steel, aluminum, nickel, titanium, fired carbon, or aluminum or stainless steel surface-treated with one of carbon, nickel, titanium, silver, or the like may be used.
The positive electrode active material in the positive electrode sheet is the positive electrode material described above.
The content of the positive electrode active material may be 80 wt% to 99 wt%, for example, 90 wt% to 99 wt%, based on the total weight of solid components in the positive electrode slurry. In the case where the amount of the positive electrode active material is 80 wt% or less, the capacity may be reduced due to a reduction in energy density.
The binder is a component that contributes to adhesion between the active material and the conductive agent and adhesion to the current collector, wherein the binder is generally added in an amount of 1 to 30 wt% based on the total weight of solid components in the positive electrode slurry. Examples of the binder may include, but are not limited to, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, various copolymers, and the like.
The conductive agent is a material that provides conductivity without causing adverse chemical changes in the battery, and may be added in an amount of 1 to 20 wt% based on the total weight of solid components in the positive electrode slurry. Examples of the conductive agent may include, but are not limited to, carbon powder such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, or thermal black; graphite powder such as natural graphite, artificial graphite or graphite having a well-grown crystal structure; conductive fibers, such as carbon fibers or metal fibers; conductive powders such as fluorocarbon powder, aluminum powder, and nickel powder; conductive whiskers such as zinc oxide whiskers and potassium titanate whiskers; conductive metal oxides such as titanium oxide; or a polyphenylene derivative.
The solvent may include: water or an organic solvent such as N-methyl-2-pyrrolidone (NMP) and alcohol, and may be used in such an amount that a desired viscosity is obtained when a cathode active material and optionally a binder and a conductive agent are included. For example, the solvent may be contained in an amount such that the concentration of the solid component in the slurry containing the positive electrode active material and optionally the binder and the conductive agent is 10 wt% to 60 wt%, for example, 20 wt% to 50 wt%.
(2) Negative electrode
The preparation method of the negative electrode can be as follows: a negative electrode current collector is coated with a negative electrode slurry including a negative electrode active material, a binder, a conductive agent, and a solvent, and then the coated negative electrode current collector is dried and rolled.
The negative electrode current collector generally has a thickness of 3 to 500 μm. The negative electrode collector is not particularly limited as long as it has high conductivity without causing adverse chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, fired carbon, or copper or stainless steel surface-treated with one of carbon, nickel, titanium, or silver, or an aluminum-cadmium alloy, or the like may be used. In addition, the negative electrode current collector may have various shapes such as a rod shape, a plate shape, a sheet shape, and a foil shape, like the positive electrode current collector.
The negative active material of the present invention may be any negative active material known in the art, including, for example, but not limited to, metallic lithium, graphite, natural graphite, artificial graphite, hard carbon, soft carbon, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO2Tin-based composite material, spinel-structured lithiated TiO2、Li4Ti5O12One or more of Li-Al alloy, silicon, Li-Si alloy, Li-Si-O alloy, silicon-based composite material and tin-silicon composite material.
The content of the anode active material may be 80 wt% to 99 wt% based on the total weight of solid components in the anode slurry.
Similar to the binder, the conductive agent and the solvent in the positive electrode, the binder, the conductive agent and the solvent in the negative electrode are added in amounts calculated based on the total weight of the solid components in the negative electrode slurry, and the specific contents, functions and kinds thereof are the same as those of the binder, the conductive agent and the solvent in the positive electrode, and are not described herein again. The skilled person can select a suitable binder, conductive agent and solvent for the negative electrode according to actual requirements.
(3) Electrolyte
The electrolyte may be one or more of a gel electrolyte, a solid electrolyte, and an electrolyte, which may include a lithium salt and a non-aqueous solvent.
The lithium salt may be selected from LiPF6、LiBF4、LiAsF6、LiClO4、LiB(C6H5)4、LiCH3SO3、LiCF3SO3、LiN(SO2CF3)2、LiC(SO2CF3)3、LiSiF6One or more of LiBOB and lithium difluoroborate. For example, LiPF is selected as lithium salt6Since it can give high ionic conductivity and improve cycle characteristics.
The non-aqueous solvent may be a carbonate compound, a carboxylate compound, an ether compound, other organic solvent, or a combination thereof.
The carbonate compound may be a chain carbonate compound, a cyclic carbonate compound, a fluoro carbonate compound, or a combination thereof. Examples of the chain carbonate compound may include, but are not limited to, diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), Methyl Propyl Carbonate (MPC), Ethyl Propyl Carbonate (EPC), Methyl Ethyl Carbonate (MEC), and combinations thereof. Examples of the cyclic carbonate compound may include, but are not limited to, Ethylene Carbonate (EC), Propylene Carbonate (PC), Butylene Carbonate (BC), Vinyl Ethylene Carbonate (VEC), and a combination thereof. Examples of the fluoro carbonate compound may include, but are not limited to, fluoroethylene carbonate (FEC), 1, 2-difluoroethylene carbonate, 1, 2-trifluoroethylene carbonate, 1,2, 2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1, 2-difluoro-1-methylethylene carbonate, 1, 2-trifluoro-2-methylethylene carbonate, trifluoromethylethylene carbonate, and combinations thereof.
Examples of the carboxylate compound may be methyl acetate, ethyl acetate, n-propyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, γ -butyrolactone, decalactone, valerolactone, mevalonic lactone, caprolactone, methyl formate, and combinations thereof.
Examples of the ether compound may be dibutyl ether, tetraglyme, diglyme, 1, 2-dimethoxyethane, 1, 2-diethoxyethane, ethoxymethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, and combinations thereof.
Examples of other organic solvents may be dimethylsulfoxide, 1, 2-dioxolane, sulfolane, methyl sulfolane, 1, 3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, and phosphate esters and combinations thereof.
(4) Diaphragm
The separator is used to separate the positive electrode and the negative electrode. The separator may be any of various separators typically used in conventional lithium ion batteries. For example, the separator may include a material having low resistance to ion migration of an electrolyte and good electrolyte retention capacity, and may include, but is not limited to, a material selected from the group consisting of: glass fibers, polyester, Teflon (Teflon), polyethylene, polypropylene, Polytetrafluoroethylene (PTFE), and combinations thereof, each of which may be woven or non-woven. The separator may have a pore size of about 0.01 μm to about 10 μm and a thickness of about 5 μm to about 300 μm.
The following are specific examples. Wherein the English abbreviations have the following meanings, LMFP is the abbreviation of lithium manganese iron phosphate, and LVP is the abbreviation of lithium vanadium phosphate.
Example 1
1. Mixing lithium acetate, ammonium metavanadate and ammonium dihydrogen phosphate according to a molar ratio of 3:2:3, adding 15 wt% of citric acid, and taking a zirconia ball as a grinding ball. The materials are added into a ball milling tank, acetone is added for mixing and wet ball milling is carried out, and slurry after wet ball milling is dried for 6 hours in an oven at 110 ℃. In N2Sintering for 6 hours at 400 ℃ under the protection of atmosphere, wherein the heating rate is 3 ℃/min, and obtaining the lithium vanadium phosphate pre-sintering powder.
2. Pre-sintering lithium vanadium phosphate powder and lithium ferric manganese phosphate precursor (the main phase is LiMn)0.7Fe0.3PO4Purchased from Jiangsu Hezhi new energy) according to the mass ratio of 0.05: 0.95, adding 8 wt% of polyvinyl alcohol (based on the total weight of the lithium vanadium phosphate pre-sintered powder and the lithium manganese iron phosphate), and grinding and mixing. Mixing well, placing in N again2Sintering at 750 ℃ for 12 hours under a protective atmosphere, wherein the heating rate is 3 ℃/min, so that the anode material is obtained after sintering, and the chemical formula of the anode material is 0.95LiMn through phase analysis (XRD)0.7Fe0.3PO4·0.05Li3V2(PO4)3(0.95LMFP 0.05LVP) as shown in FIG. 1.
Example 2
The preparation method of example 2 is substantially the same as that of example 1 except that: in the step 2, the mass ratio of the lithium vanadium phosphate pre-firing powder to the lithium manganese phosphate is 0.1: 0.9.
The chemical formula of the cathode material prepared in example 2 was 0.9LiMn by phase analysis (XRD)0.7Fe0.3PO4·0.1Li3V2(PO4)3(0.9LMFP 0.1LVP) as shown in FIG. 1.
Example 3
The preparation method of example 2 is substantially the same as that of example 1 except that: in the step 2, the mass ratio of the lithium vanadium phosphate pre-firing powder to the lithium manganese phosphate is 0.3: 0.7.
The chemical formula of the positive electrode material prepared in example 2 was 0.7LiMn by phase analysis (XRD)0.7Fe0.3PO4·0.3Li3V2(PO4)3(0.7LMFP 0.3LVP) as shown in FIG. 1.
Comparative example 1
Lithium manganese iron phosphate (LiMn)0.7Fe0.3PO4)
Structural characterization
And (3) observing the crystal structure of the material by adopting X-ray diffraction (XRD), and observing the morphology and the particle size of the cathode material by adopting a Scanning Electron Microscope (SEM), EDS elemental analysis and a projection electron microscope (TEM).
Phase analysis of positive electrode material (XR)
As can be seen from FIG. 1, the factLiMn, a positive electrode material prepared in examples 1 to 30.7Fe0.3PO4And Li3V2(PO4)3Two phases coexist, no obvious peak position shift and other miscellaneous peaks are generated, which indicates that the prepared anode material has no obvious crystal orientation impurity, and Li is added along with the increase of the proportion of the added lithium vanadium phosphate pre-sintering powder3V2(PO4)3The peak intensity ratio of (a) also becomes high, indicating that Li is contained in the positive electrode material3V2(PO4)3The content is also increased.
Morphology analysis of cathode material (SEM & EDS & TEM)
Referring to fig. 2 and 3, fig. 2(a) shows lithium manganese iron phosphate (LiMn)0.7Fe0.3PO4) The morphology of (A) in FIG. 2 is 0.95 LMFP.0.05 LVP, the morphology of (C) in FIG. 2 is 0.9 LMFP.0.1 LVP, the morphology of (D) in FIG. 2 is 0.7 LMFP.0.3 LVP, and the morphology of (E) in FIG. 2 is lithium manganese iron phosphate (LiMn)0.7Fe0.3PO4) The EDS element distribution chart of (a) in FIG. 2(f) is an EDS element distribution chart of 0.9LMFP 0.1 LVP. FIG. 2(e) lithium manganese iron phosphate (LiMn)0.7Fe0.3PO4) The EDS element distribution diagram of (1) has no V element, and the EDS element distribution diagram of (f) FIG. 2 has V element in 0.9 LMFP.0.1 LVP. FIGS. 3(a) - (c) are lithium manganese iron phosphate (LiMn)0.7Fe0.3PO4) FIG. 3(d) to (f) are (HR) TEM images of 0.9 LMFP.0.1 LVP.
As can be seen from FIGS. 2 and 3, the particle size of the positive electrode materials prepared in examples 1 to 3 is 100nm to 150nm, from which LiMn can be clearly distinguished0.7Fe0.3PO4And Li3V2(PO4)3Two kinds of particles, the particles are ellipsoidal. Compared with lithium manganese iron phosphate (LiMn)0.7Fe0.3PO4) (FIGS. 3a to 3c), 0.9LiMn0.7Fe0.3PO4·0.1Li3V2(PO4)3(FIGS. 3d-3f) sp with transparent wrinkles2Type carbon (i.e., graphene), and 0.9LiMn0.7Fe0.3PO4·0.1Li3V2(PO4)3In which a clear distinction can be observedThe two lattice fringes (FIG. 3f) with interplanar spacings of 0.427nm and 0.214nm correspond to the (011) crystal plane of LMFP and the (400) crystal plane of LVP, respectively.
Preparing a battery:
the battery type is a button battery, and the model is CR 2032.
The electrolyte is 1mol/L lithium hexafluorophosphate as a solute, and the solvent is a mixture of 1: 1: 1 ethylene carbonate, methyl ethyl carbonate and dimethyl carbonate, and 1 percent of VC is added as a film forming additive. The isolating membrane is a celgard2400 polypropylene porous membrane.
Preparing a positive plate: the positive electrode material provided in example 1, the conductive agent C45, and the binder polyvinylidene fluoride were mixed in a mass ratio of 8: 1: 1, dissolving polyvinylidene fluoride in N-methyl pyrrolidone, wherein the mass fraction of polyvinylidene fluoride is 5%, uniformly mixing, coating on an aluminum foil, wherein the thickness is 200 mu m, and drying in vacuum at 60 ℃ for 6 hours to prepare the electrode slice with the diameter of phi 12 mm. The loading capacity of the active substances of the electrode slice is about 1.5-2.5 mg. The cathode plate is a pure metal lithium plate. And assembling the battery in a glove box under the protection of argon.
Accordingly, batteries were prepared in the same manner using the materials provided in examples 2 to 3 and comparative example 1 as positive electrode materials.
Electrochemical performance test
Testing a voltage interval: 2.2-4.5V.
Testing current: and 1C is 160 mA/g.
Battery test temperature: room temperature 25. + -. 2 ℃.
Referring to FIGS. 4 to 6, the results of the cell performance tests of examples 1 to 3 and comparative example 1.
Table 1 shows the results of the rate tests of examples 1 to 3 and comparative example 1.
Figure BDA0003140566150000141
Compared to LiMn provided in comparative example 10.7Fe0.3PO4And 0.95LiFePO as provided in comparative example 24·0.05Li3V2(PO4)3(0.95LMFP 0.05LVP), the batteries made of the positive electrode materials provided in examples 1-3 have obviously improved high rate performance and better cycle stability.
In addition, it can be seen from FIG. 4 that the phase of LiMn is relatively pure0.7Fe0.3PO4New platforms of 3.59V and 3.68V appeared, corresponding to Li3V2(PO4)3The V has a reversible valence of +3/+4, and the plateau capacity contributions of 3.59V and 3.68V are increased along with the increase of the proportion of the lithium vanadium phosphate pre-sintering powder, so the rate performance of the battery is improved more, because the carbon form is further sp along with the increase of the LVP proportion2And (4) carrying out type conversion. However, in example 3, a certain loss of reversible specific capacity occurred compared to example 2, since Li was present in the voltage range of 2.2-4.5V3V2(PO4)3Has a theoretical specific capacity of 133mAh g-1Lower than LiMn0.7Fe0.3PO4(160mAh g-1) However, it can still be found that 0.7LiMn0.7Fe0.3PO4·0.3Li3V2(PO4)3The cycle stability and the high rate performance of the composite material are greatly improved.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, so as to understand the technical solutions of the present invention specifically and in detail, but not to be understood as the limitation of the protection scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. It should be understood that the technical solutions provided by the present invention, which are obtained by logical analysis, reasoning or limited experiments, are within the scope of the appended claims. Therefore, the protection scope of the present invention should be subject to the content of the appended claims, and the description and the drawings can be used for explaining the content of the claims.

Claims (10)

1. The positive electrode material is characterized by comprising the main component of lithium manganese iron phosphate LiMn0.7Fe0.3PO4And lithium vanadium phosphate Li3V2(PO4)3And the substrate is coated with graphene.
2. The positive electrode material according to claim 1, wherein the mass ratio of the lithium vanadium phosphate to the lithium manganese iron phosphate is x (1-x), wherein x is greater than 0 and less than or equal to 0.3.
3. The positive electrode material according to claim 1, wherein the graphene content is 2 to 3 wt% based on the total weight of the positive electrode material.
4. A method for producing a positive electrode material according to any one of claims 1 to 3, comprising the steps of:
mixing a lithium source, a vanadium source, a phosphorus source and a first carbon source according to a preset ratio to obtain a precursor of the lithium vanadium phosphate;
sintering the precursor of the lithium vanadium phosphate in an inert atmosphere to obtain lithium vanadium phosphate pre-sintered powder;
mixing the lithium vanadium phosphate pre-firing powder, the precursor of the lithium ferric manganese phosphate and a second carbon source according to a preset ratio to obtain a precursor of a positive electrode material;
and sintering the precursor of the positive electrode material in an inert atmosphere to obtain the positive electrode material.
5. The method for preparing the cathode material according to claim 4, wherein the lithium source is at least one of lithium dihydrogen phosphate, lithium nitrate, lithium acetate and lithium hydroxide, the vanadium source is one or more of vanadium pentoxide, vanadium trioxide, vanadium dioxide and ammonium metavanadate, and the phosphorus source is at least one of ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate and phosphoric acid.
6. The method for producing a positive electrode material according to claim 4, wherein the first carbon source is a carbon-containing compound including one or more of a sugar, an organic acid vinegar, a small molecule alcohol, and another carbon-containing high molecule compound.
7. The method for preparing the positive electrode material according to claim 4, wherein the second carbon source is one or more of glucose, polyvinyl alcohol, polyallyl alcohol, and polybutyl alcohol.
8. The method for producing a positive electrode material according to claim 4, wherein the sintering temperature is 300 to 400 ℃ and the sintering time is 4 to 6 hours when the precursor of lithium vanadium phosphate is sintered.
9. The method for producing a positive electrode material according to claim 4, wherein the sintering temperature is 650 to 800 ℃ and the sintering time is 8 to 16 hours when the positive electrode precursor is sintered.
10. A lithium ion battery, characterized in that a positive electrode comprises the positive electrode material according to any one of claims 1 to 3.
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023273917A1 (en) * 2021-06-30 2023-01-05 清华大学 Positive electrode material and preparation method therefor, and lithium ion battery
CN115709976A (en) * 2022-11-15 2023-02-24 广东国光电子有限公司 Modified lithium iron manganese phosphate material, preparation method thereof and battery
CN117117120A (en) * 2023-08-02 2023-11-24 天津凯莫赛新能源技术开发中心 Vanadium-containing self-supplementing lithium composite phosphate positive electrode material and preparation method and application thereof

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117246990B (en) * 2023-11-16 2024-03-05 合肥国轩高科动力能源有限公司 Lithium iron manganese phosphate, preparation method thereof and lithium ion battery

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106025226A (en) * 2016-07-13 2016-10-12 中国科学技术大学 Cathode material for sodium-ion battery, preparation method of cathode material and sodium-ion battery
CN107799730A (en) * 2016-08-31 2018-03-13 苏州艾美得新能源材料有限公司 Method for preparing anode material, positive electrode and battery

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108172794B (en) * 2017-12-27 2020-02-21 中科廊坊过程工程研究院 Composite cathode material and preparation method and application thereof
CN113571705A (en) * 2021-06-30 2021-10-29 清华大学 Cathode material, preparation method thereof and lithium ion battery

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106025226A (en) * 2016-07-13 2016-10-12 中国科学技术大学 Cathode material for sodium-ion battery, preparation method of cathode material and sodium-ion battery
CN107799730A (en) * 2016-08-31 2018-03-13 苏州艾美得新能源材料有限公司 Method for preparing anode material, positive electrode and battery

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
BAO ZHANG 等: "Porous spherical LiFePO4·LiMnPO4·Li3V2(PO4)3@C@rGO composites as a high-rate and long-cycle cathode for lithium ion batteries", 《CERAMICS INTERNATIONAL》 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023273917A1 (en) * 2021-06-30 2023-01-05 清华大学 Positive electrode material and preparation method therefor, and lithium ion battery
CN115709976A (en) * 2022-11-15 2023-02-24 广东国光电子有限公司 Modified lithium iron manganese phosphate material, preparation method thereof and battery
CN115709976B (en) * 2022-11-15 2023-11-03 广东国光电子有限公司 Modified lithium iron manganese phosphate material, preparation method thereof and battery
CN117117120A (en) * 2023-08-02 2023-11-24 天津凯莫赛新能源技术开发中心 Vanadium-containing self-supplementing lithium composite phosphate positive electrode material and preparation method and application thereof

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