WO2024104075A1 - 一种磷酸盐前驱体及其制备方法、正极材料及其制备方法、正极片和二次电池 - Google Patents

一种磷酸盐前驱体及其制备方法、正极材料及其制备方法、正极片和二次电池 Download PDF

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WO2024104075A1
WO2024104075A1 PCT/CN2023/126835 CN2023126835W WO2024104075A1 WO 2024104075 A1 WO2024104075 A1 WO 2024104075A1 CN 2023126835 W CN2023126835 W CN 2023126835W WO 2024104075 A1 WO2024104075 A1 WO 2024104075A1
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positive electrode
phosphate precursor
phosphate
carbon
electrode material
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French (fr)
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徐健
李诗文
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高点(深圳)科技有限公司
上海锦源晟新能源材料有限公司
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Publication of WO2024104075A1 publication Critical patent/WO2024104075A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/26—Phosphates
    • C01B25/45—Phosphates containing plural metal, or metal and ammonium
    • 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
    • H01M4/04—Processes of manufacture in general
    • 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
    • H01M4/139—Processes of manufacture
    • H01M4/1397—Processes of manufacture of electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • 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
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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
    • 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

Definitions

  • the present invention belongs to the technical field of secondary batteries, and in particular relates to a phosphate precursor and a preparation method thereof, a positive electrode material and a preparation method thereof, a positive electrode sheet and a secondary battery.
  • the mainstream preparation process of phosphate cathode materials for secondary lithium-ion batteries can be divided into two major routes: solid phase method and liquid phase method.
  • the solid phase method mostly uses mechanical grinding to mix the raw materials, and under the protection of an inert atmosphere, an olivine-type phosphate cathode material is prepared through a high-temperature reaction of 700 to 850°C.
  • This method is characterized by simple operation, but due to the uneven mixing of raw materials, segregation is prone to occur, resulting in poor consistency of the product and affecting the electrical properties of the material.
  • the energy consumption is high and the production cycle is long.
  • Liquid phase reactions make it easier to mix reactants evenly than solid phase reactions.
  • nanoscale or even molecular-level mixed materials can be prepared.
  • the common liquid phase method is mainly hydrothermal method.
  • the hydrothermal method usually uses ferrous sulfate, phosphoric acid, and lithium hydroxide as raw materials.
  • the synthesis temperature is about 140-210°C
  • the pressure is about 1.4MPa
  • the reaction time is about 3-24h.
  • the material is filtered and washed, and then vacuum dried to obtain lithium iron phosphate, which can be further carbon-coated to improve the electrical performance.
  • the final product has good electrochemical properties, but the lithium ion utilization rate of this method is as low as 1/3, the raw material cost is too high, and the yield is low. High-voltage equipment is required, and large-scale production cannot be achieved.
  • Patent CN103259015B adopts a two-step method, first preparing Li 3 PO 4 , and then preparing lithium iron phosphate by hydrothermal method.
  • the product particles are uniform and consistent.
  • the yield of this method is low, and high pressure is required during the preparation process, which is highly dangerous.
  • the design and manufacture of large-scale high-temperature and high-pressure reactors are difficult and expensive, making it difficult to achieve large-scale production.
  • sol-gel method Another method for preparing phosphate cathode materials is the sol-gel method, which can use nitrates, acetates
  • Raw materials that are easy to decompose at high temperatures such as Fe(NO 3 ) 2 , H 3 PO 4 and LiCH 3 COO, are used as precursors to synthesize gel, and then LiFePO 4 powder is obtained after sintering at 600°C ⁇ 700°C for 4 ⁇ 24h in a nitrogen atmosphere.
  • the sol-gel method has high raw material costs and is difficult to achieve industrial application.
  • lithium carbonate, phosphate, iron nitrate, strong oxidant, strong acid, polymer monomer, etc. are used, and the self-thermal evaporation method is adopted to reduce energy consumption, so that the polymerization of polymer monomer and the nucleus formation of lithium iron phosphate are carried out simultaneously to control the morphology and particle size of the final product, and obtain a phosphate positive electrode material with good consistency.
  • This method requires the removal of by-products such as ammonium nitrate under high temperature conditions of 700-780°C to prepare lithium iron phosphate.
  • the lithium iron phosphate prepared by this method has good electrochemical properties, but strong oxidants and strong acids are required in the preparation process, which is highly dangerous.
  • by-products such as ammonium nitrate are removed at high temperature, and a large amount of nitrogen oxide gas is generated in the process, which pollutes the environment and is highly dangerous.
  • One of the purposes of the present invention is to provide a phosphate precursor for the deficiencies of the prior art, which has good uniformity, contains crystal water, has good structural stability, and can prepare an olivine-type phosphate positive electrode material under low-temperature sintering conditions of 260°C to 600°C, and the positive electrode material has good electrochemical properties.
  • a phosphate precursor the chemical formula of the phosphate precursor is Li x My (PO 4 ) (x+y)/2 A z ⁇ wH 2 O, wherein M is a transition metal element, the transition metal element is one or more of Fe, Ti, V, Cr, Ni, Co, Mn, Al, Nb, Y, Zr, Sb, Mo, Sn, Ce, A is one or more of F - , OH - , CO 3 2- , C 2 O 4 2- , O 2- , wherein 0.5 ⁇ x ⁇ 1.2, 0.5 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 1, 0.1 ⁇ w ⁇ 8.
  • the transition metal element contains one or two of Fe, Mn, and Co.
  • characteristic peaks F1 9.0° ⁇ 11.5°
  • characteristic peak F2 22.1° ⁇ 22.8°
  • characteristic peak F3 22.9° ⁇ 23.5°
  • characteristic peak F4 24.5° ⁇ 25.1°
  • the ratio of the characteristic peaks F1 to F3 is 0.02 ⁇ 100.
  • the mass fraction of lithium in the phosphate precursor is 1% to 5.3%
  • the mass ratio of lithium element to transition metal element in the phosphate precursor is 5.8% to 30.3%
  • the mass ratio of lithium element to phosphorus element is 1.5% to 2.0%.
  • the quantity ratio is 14.8% to 31.6%.
  • the particle size D 50 of the phosphate precursor is 0.05-20 ⁇ m.
  • the morphology of the phosphate precursor is one or more of spherical, quasi-spherical, lamellar, and strip-shaped.
  • the second object of the present invention is to provide a method for preparing a phosphate precursor in view of the shortcomings of the prior art, by adding a colloidal auxiliary agent to at least one or more of a transition metal salt solution, a lithium source solution or a phosphorus source solution to obtain a colloidal liquid; then the colloidal liquid and the raw materials are mixed and stirred, and multiphase precipitation occurs in a colloidal system, and the surfactant and the polymer in the colloidal liquid are used to prevent the colloidal particles from agglomerating, so that the distribution of different particles in the precipitation process can reach a mixed state of nanometer and submicron levels; at the same time, the addition of a degumming agent is controlled to break the colloidal balance so that different particles are combined into a precipitate; and the precipitate is aged, washed, and dried to obtain a phosphate precursor with good uniformity.
  • a method for preparing a phosphate precursor comprises the following steps:
  • Step S1 dispersing a soluble transition metal salt in a solvent to obtain a transition metal salt solution, dispersing a soluble lithium salt in a solvent to obtain a lithium source solution, and dispersing a phosphorus-containing compound in a solvent to obtain a phosphorus source solution;
  • Step S2 dispersing the polymer in a solvent and stirring to disperse to obtain a colloid auxiliary agent
  • Step S3 adding a colloidal auxiliary agent to at least one of the transition metal salt solution, the lithium source solution or the phosphorus source solution in step S1 to obtain a colloidal solution;
  • Step S4 adding a surfactant, a breaker, the colloid solution in step S3 and the remaining solution in step S1 into a reactor, controlling the temperature, mixing and stirring under atmospheric conditions, causing a multiphase precipitation reaction, and obtaining a precipitate;
  • Step S5 aging, washing and drying the precipitate in step S4 to obtain a phosphate precursor.
  • the solid content of the transition metal salt solution in step S1 is 1.5% to 30%, the solid content of the lithium source solution is 1.1% to 27%, and the mass fraction of the phosphorus source solution is 1% to 25%.
  • the transition metal salt solution in step S1 includes one or more of the metal elements Fe, Ti, V, Cr, Ni, Co, Mn, Al, Nb, Y, Zr, Sb, Mo, Sn, and Ce.
  • the preparation method of the colloid auxiliary agent in step S2 is to add a polymer to a solvent, heat it to 20°C to 100°C, and stir and disperse it for 30 to 300 minutes, wherein the weight proportion of the polymer in the colloid auxiliary agent is 0.1% to 20%, wherein the polymer is one or a mixture of several selected from methyl cellulose, starch, polyacrylamide, polyvinyl pyrrolidone, polypropylene alcohol, agar, carrageenan, gum arabic, guar gum, and tamarind gum.
  • the weight percentage of the polymer in the colloid liquid in step S3 is 0.02% to 2%, wherein.
  • the atmosphere in step S4 is nitrogen, argon or carbon dioxide.
  • the specific operation of drying described in step S5 is heating to 70°C-200°C in a vacuum environment and drying to constant weight, or heating to 100°C-200°C in an air environment and drying to constant weight, more preferably, heating to 70°C-200°C in a vacuum environment and drying to constant weight.
  • the third object of the present invention is to provide a method for preparing a phosphate positive electrode material in view of the shortcomings of the prior art, which is simple to prepare, uses a lower temperature for heat treatment, consumes less energy, has low cost, does not produce toxic and harmful gases such as nitrogen oxides, has less pollution emissions, and has good safety.
  • a method for preparing a phosphate positive electrode material comprises heating the phosphate precursor to 260°C to 600°C in an oxygen-free atmosphere such as argon, nitrogen or a hydrogen-argon mixed gas, and cooling after heat treatment for 2 to 72 hours.
  • an oxygen-free atmosphere such as argon, nitrogen or a hydrogen-argon mixed gas
  • the fourth object of the present invention is to provide a phosphate positive electrode material with low production cost, good performance and stability in view of the shortcomings of the prior art.
  • a phosphate positive electrode material is obtained by the above-mentioned preparation method of the phosphate positive electrode material.
  • the phosphate positive electrode material has a 0.1C discharge specific capacity of 100-140 mAh/g at room temperature.
  • the fifth object of the present invention is to provide a method for preparing a carbon-doped positive electrode material in view of the shortcomings of the prior art, which uses a lower temperature for heat treatment, consumes less energy, has lower cost, does not produce toxic and harmful gases such as nitrogen oxides, and has good safety.
  • a method for preparing a carbon-doped positive electrode material comprises mixing the above-mentioned phosphate precursor or phosphate positive electrode material with a carbon source, heating to 260°C to 600°C in an oxygen-free atmosphere such as argon, nitrogen or a hydrogen-argon mixed gas, and cooling after heat treatment for 2 to 72 hours.
  • a carbon source such as argon, nitrogen or a hydrogen-argon mixed gas
  • the carbon source is one or more of glucose, fructose, sucrose, starch, graphite, graphene, carbon nanotubes, and polyvinyl pyrrolidone.
  • the sixth object of the present invention is to provide a carbon-doped positive electrode material with good electrical properties and stability in view of the deficiencies in the prior art.
  • a carbon-doped positive electrode material is obtained by the above-mentioned method for preparing the carbon-doped positive electrode material.
  • the carbon-doped positive electrode material has a 0.1C rate discharge specific capacity of 140-160 mAh/g at room temperature.
  • the mass ratio of carbon element to lithium element in the carbon-doped positive electrode material is 11.4% to 182.1%
  • the source of the carbon element includes one or more of amorphous carbon, graphite, graphene, and carbon nanotubes.
  • the seventh object of the present invention is to provide a positive electrode sheet with good electrochemical performance in view of the deficiencies in the prior art.
  • a positive electrode sheet comprises a positive electrode current collector and a positive electrode coating arranged on at least one surface of the positive electrode current collector, wherein the positive electrode coating comprises the above-mentioned carbon-doped positive electrode material.
  • An eighth object of the present invention is to provide a secondary battery with good electrochemical performance in view of the deficiencies in the prior art.
  • a secondary battery comprises the above-mentioned positive electrode sheet.
  • a phosphate precursor of the present invention is a hydrate, has good uniformity and good structural stability. Under the condition of low-temperature sintering at 260°C to 600°C, an olivine-type phosphate positive electrode material can be prepared, and no toxic and harmful gases such as nitrogen oxides are generated during the process, and the electrochemical performance of the positive electrode material is good.
  • a preparation method of a phosphate precursor of the present invention is to prepare a colloidal liquid by adding a colloidal auxiliary agent, and multiphase precipitation occurs under the colloidal system, and the surfactant and the polymer in the colloidal liquid are used to prevent the colloidal particles from flocculating, so that the distribution of different particles in the precipitation process reaches a mixed state of nanometer and submicron levels, and then by controlling the addition of a decolloiding agent, the colloidal balance is broken, so that different particles are combined into a precipitate, and then the precipitate is aged, washed, and dried to obtain a phosphate precursor with good uniformity.
  • FIG1 is an enlarged schematic diagram of a phosphate precursor according to Example 1 of the present invention.
  • FIG. 2 is an XRD diagram of the phosphate precursor of Example 1 of the present invention.
  • FIG3 is an enlarged schematic diagram of the phosphate positive electrode material obtained after heat treatment in Example 1 of the present invention.
  • FIG. 4 is an XRD diagram of the phosphate positive electrode material obtained after heat treatment in Example 1 of the present invention.
  • FIG5 is an XRD diagram of the material obtained after heat treatment in Comparative Example 1.
  • FIG6 is a discharge curve of a battery made of the carbon-doped positive electrode material obtained in Examples 11 and 12 of the present invention.
  • a phosphate precursor of the present invention has a chemical formula of Li x M y (PO 4 ) (x+y)/2 A z ⁇ wH 2 O, wherein M is a transition metal element, and the transition metal element is one or more of Fe, Ti, V, Cr, Ni, Co, Mn, Al, Nb, Y, Zr, Sb, Mo, Sn, and Ce, and A is one or more of F - , OH - , CO 3 2- , C 2 O 4 2- , and O 2- , wherein 0.5 ⁇ x ⁇ 1.2, 0.5 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 1, and 0.1 ⁇ w ⁇ 8.
  • the phosphate precursor of the present invention is a hydrate and has bound water.
  • the transition metal element, lithium element, and phosphorus element are evenly distributed to form a stable structure, and a positive electrode material can be prepared under the condition of low-temperature sintering at 260° C. to 600° C., and the process is simple and the energy consumption is low.
  • the phosphate precursor has a characteristic peak F1 of 9.0° to 11.5°, a characteristic peak F2 of 22.1° to 22.8°, a characteristic peak F3 of 22.9° to 23.5°, and a characteristic peak F4 of 24.5° to 25.1° in the XRD spectrum of the 2 ⁇ diffraction angle of the copper target k ⁇ 1, and the ratio of the characteristic peaks F1 to F3 is 0.02 to 100.
  • the mass fraction of lithium in the phosphate precursor is 1% to 5.3%
  • the mass ratio of lithium to transition metal elements in the phosphate precursor is 5.8% to 30.3%
  • the mass ratio of lithium to phosphorus is 14.8% to 31.6%.
  • the mass fraction of lithium in the phosphate precursor is 1%, 1.2%, 1.5%, 1.7%, 1.9%, 2%, 2.5%, 3%, 3.4%, 4%, 4.5%, 5%, 5.3%
  • the mass ratio of lithium to transition metal elements in the phosphate precursor is 6.2%, 7.5%, 8.7%, 9.9%, 11.1%, 12.4%, 13.6%, 15.5%, 17.7%, 20.7%, 24.8%, 27.3%
  • the mass ratio of lithium to phosphorus is 14.8% to 31.6%.
  • the mass ratios of iodine and phosphorus are 14.8%, 16.8%, 18.4%, 19.9%, 22.4%, 24.4%, 26.9% and 29.9%.
  • the transition metal element is manganese.
  • the transition metal element is iron.
  • the transition metal elements are iron and manganese, wherein the mass ratio of iron to total transition metal elements is ⁇ 0.1.
  • the particle size D50 of the phosphate precursor is 0.05-20 ⁇ m.
  • the particle size D50 of the phosphate precursor is 0.05 ⁇ m, 0.1 ⁇ m, 0.5 ⁇ m, 0.9 ⁇ m, 1 ⁇ m, 1.6 ⁇ m, 3 ⁇ m, 4 ⁇ m, 8 ⁇ m, 10 ⁇ m, 15 ⁇ m, 18 ⁇ m, 19 ⁇ m, 20 ⁇ m.
  • the morphology of the phosphate precursor is one or more of spherical, quasi-spherical, lamellar, and strip-shaped.
  • a method for preparing a phosphate precursor of the present invention comprises the following steps:
  • Step S1 dispersing a soluble transition metal salt in a solvent to obtain a transition metal salt solution, dispersing a soluble lithium salt in a solvent to obtain a lithium source solution, and dispersing a phosphorus-containing compound in a solvent to obtain a phosphorus source solution;
  • Step S2 dispersing the polymer in a solvent and stirring to disperse to obtain a colloid auxiliary agent
  • Step S3 adding a colloidal auxiliary agent to at least one of the transition metal salt solution, the lithium source solution or the phosphorus source solution in step S1 to obtain a colloidal solution;
  • Step S4 adding the colloid liquid, surfactant, breaker in step S3 and the remaining solution in step S1 into a reactor, controlling the temperature, mixing and stirring under atmospheric conditions, and causing multiphase precipitation;
  • Step S5 aging, washing and drying the precipitate in step S4 to obtain a phosphate precursor.
  • the invention discloses a method for preparing a phosphate precursor, comprising the steps of adding a colloidal auxiliary agent to at least one or more of a transition metal salt solution, a lithium source solution or a phosphorus source solution to obtain a colloidal liquid; mixing and stirring the colloidal liquid and a raw material, and causing multiphase precipitation in a colloidal system; utilizing a surfactant and a polymer in the colloidal liquid to play a repulsive role to prevent colloidal particles from flocculating, so that different particle distributions in the precipitation process can reach a mixed state of nanometer and submicron levels; controlling the addition of a decolloiding agent to break the colloidal equilibrium, so that different particles are combined into a precipitate; and aging, washing and drying the precipitate to obtain a precipitate with good uniformity.
  • Phosphate Precursors Phosphate Precursors.
  • the solvent is water, ethanol or isopropanol.
  • the atmosphere is an oxygen-free atmosphere selected from argon, nitrogen or a hydrogen-argon mixture.
  • the cation of the soluble transition metal salt is one or more of the ions formed by the loss of one or more electrons of Fe, Ti, V, Cr, Ni, Co, Mn, Al, Nb, Y, Zr, Sb, Mo, Sn, and Ce atoms, and the anion may be one or more of SO 4 2- , SO 3 2- , NO 3 - , Cl - , CH 3 COO - , and C 6 H 5 O 7 3- .
  • the soluble transition metal salt is one or more of iron salts, manganese salts, and cobalt salts.
  • the iron salt includes one or more of ferrous sulfate, ferrous chloride, ferrous nitrate, ferrous acetate, ferrous sulfite, ferric sulfate, ferric chloride, and ferric nitrate.
  • the manganese salt includes one or more of manganese sulfate, manganese nitrate, manganese chloride, manganese acetate, manganese citrate, and manganese sulfite.
  • the cobalt salt includes one or more of cobalt sulfate, cobalt nitrate, cobalt chloride, cobalt acetate, cobalt citrate, and cobalt sulfite.
  • the soluble lithium salt includes one or more of lithium oxalate, lithium sulfate, lithium chloride, lithium nitrate, lithium sulfite, lithium chlorate, lithium perchlorate, lithium bromide, lithium bromate, lithium iodide, lithium thiocyanate, lithium nitrite, lithium formate, lithium acetate, and lithium citrate.
  • the phosphorus-containing compound includes one or more of phosphoric acid, monoammonium phosphate, diammonium phosphate, triammonium phosphate, monosodium phosphate, disodium phosphate, and trisodium phosphate.
  • the colloid auxiliary agent includes one or a mixture of methylcellulose, starch, polyacrylamide, polyvinyl pyrrolidone, polypropylene alcohol, polyacrylonitrile, agar, carrageenan, gum arabic, guar gum, and tamarind gum.
  • the surfactant includes one or more of polyethylene glycol, CTAB, fatty alcohol polyoxyethylene ether, fatty acid polyoxyethylene ester, alkyl polysaccharide, alkyl alcohol amide, ethoxylated sorbitan fatty acid ester, etc.
  • the breaker includes one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonia water, ammonium carbonate, ammonium bicarbonate, lithium hydroxide, lithium carbonate, lithium bicarbonate, potassium hydroxide, potassium carbonate, and potassium bicarbonate.
  • the solid content of the breaker is 1% to 16%, preferably, the solid content of the breaker is 1%, 5%, 8%, 9%, 10%, 14%, 15%, 15.5%, 16%.
  • the solid content of the transition metal salt solution is 1.5% to 30%
  • the solid content of the lithium source solution is 1.1% to 27%
  • the mass fraction of the phosphorus source solution is 1% to 25%.
  • the solid content of the salt solution is 1.5% to 10%, 10% to 20%, 20% to 30%, specifically, the solid content of the transition metal salt solution is 1.5%, 4%, 5%, 8%, 10%, 15%, 18%, 20%, 24%, 27%, 29%, 30%, preferably, the solid content of the lithium source solution is 1.1% to 10%, 10% to 15%, 15% to 20%, 20% to 27%, specifically The solid content of the lithium source solution is 1.1%, 4%, 5%, 8%, 10%, 15%, 18%, 20%, 24%, 27%.
  • the mass fraction of the phosphorus source solution is 1% to 10%, 10% to 15%, 15% to 20%, 20% to 25%. Specifically, the mass fraction of the phosphorus source solution is 1.5%, 4%, 5%, 8%, 10%, 15%, 18%, 20%, 24%, 25%.
  • the transition metal salt solution, the lithium source solution, and the phosphorus source solution are set to a certain solid content so that the reaction is more complete and more uniform, and the prepared phosphate precursor has better performance.
  • the preparation method of the colloid auxiliary agent in step S2 is to add the polymer to the solvent, heat to 20°C to 100°C, and stir and disperse for 30 to 300 minutes.
  • the heating temperature is 20°C to 40°C, 40°C to 60°C, 60°C to 80°C, 80°C to 100°C, specifically, the heating temperature is 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C
  • the stirring and dispersing time is 30 to 60 minutes, 60 to 120 minutes, 120 to 300 minutes, specifically, the stirring and dispersing time is 30 minutes, 60 minutes, 90 minutes, 120 minutes, 180 minutes, 300 minutes.
  • the polymer accounts for 0.1% to 20% by weight of the colloid adjuvant, and the polymer is one or a mixture of methyl cellulose, starch, polyacrylamide, polyvinyl pyrrolidone, polyacryl alcohol, agar, carrageenan, gum arabic, guar gum, and tamarind gum.
  • the polymer accounts for 0.1% to 8%, 8% to 16%, 16% to 20% by weight of the colloid adjuvant, specifically, the polymer accounts for 0.1%, 2%, 5%, 8%, 10%, 11%, 14%, 15%, 16%, 18%, 20% by weight of the colloid adjuvant;
  • the weight percentage of the polymer in the colloidal liquid is 0.02% to 2%.
  • the weight percentage of the polymer in the colloidal liquid is 0.02% to 1%, 1% to 2%.
  • the weight percentage of the polymer in the colloidal liquid is 0.02%, 0.08%, 0.1%, 0.2%, 0.8%, 0.86%, 1%, 1.2%, 1.6%, 1.8%, 1.9%, or 2%.
  • nitrogen, argon, Carbon dioxide gas is used for protection to prevent oxidation of the material, so as to avoid segregation of element ratios during the precipitation process.
  • the specific operation of drying in step S5 is heating to 70°C to 200°C in a vacuum environment and drying to constant weight, or heating to 100°C to 200°C in an air environment and drying to constant weight, preferably, heating to 70°C to 200°C in a vacuum environment and drying to constant weight.
  • drying free water in the material is removed to obtain a product containing crystal water, which has good stability.
  • a method for preparing a phosphate positive electrode material wherein the phosphate precursor is heated to 260°C to 600°C in an oxygen-free atmosphere such as argon, nitrogen or a hydrogen-argon mixture, and the temperature is lowered after heat treatment for 2 to 72 hours.
  • the heating temperature may be 260°C, 280°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, or 600°C.
  • the heat treatment time may be 4 hours, 8 hours, 10 hours, 16 hours, 24 hours, 30 hours, 36 hours, 48 hours, 50 hours, 60 hours, or 72 hours.
  • a phosphate positive electrode material is obtained by the above-mentioned preparation method of the phosphate positive electrode material. After the phosphate positive electrode material is made into a lithium ion battery, the 0.1C discharge specific capacity at room temperature reaches 100-130 mAh/g.
  • a method for preparing a carbon-doped positive electrode material comprising mixing a phosphate precursor with a carbon source, heating to 260°C to 600°C in an oxygen-free atmosphere such as argon, nitrogen or a hydrogen-argon mixture, and heat treating for 2 to 72 hours to obtain the obtained material.
  • the carbon source is one or more of glucose, fructose, sucrose, starch, graphite, graphene, carbon nanotubes, and polyvinyl pyrrolidone.
  • the heating temperature is 260°C, 300°C, 350°C, 380°C, 400°C, 420°C, 450°C, 480°C, 500°C, 550°C, and 600°C.
  • the reaction time is 2 hours, 4 hours, 6 hours, 8 hours, 12 hours, 15 hours, 18 hours, 20 hours, 25 hours, 29 hours, 32 hours, 37 hours, 39 hours, 40 hours, 43 hours, 46 hours, 48 hours, 50 hours, 55 hours, 60 hours, 65 hours, 70 hours, and 72 hours.
  • the mass ratio of carbon element to lithium element in the carbon-doped positive electrode material is 11.4% to 182.1%, and the composition of the C element can be one or more of amorphous carbon, graphite, graphene, and carbon nanotubes, preferably amorphous carbon and carbon nanotubes.
  • a carbon-doped positive electrode material obtained by the above-mentioned preparation method of the carbon-doped positive electrode material has good Electrical performance and stability.
  • a positive electrode sheet comprises a positive electrode current collector and a positive electrode coating disposed on at least one surface of the positive electrode current collector, wherein the positive electrode coating comprises the above-mentioned carbon-doped positive electrode material.
  • the positive electrode sheet of the present invention has good electrochemical performance.
  • a secondary battery comprises the above-mentioned positive electrode sheet.
  • Step S1 weigh 278.01g of ferrous sulfate heptahydrate (1mol), add 500g of water to stir and dissolve, and prepare a transition metal salt solution with a solid content of 19.5%; weigh 50.95g of lithium oxalate (0.5mol), add 700g of water to dissolve, and prepare a lithium solution with a solid content of 12.7%; weigh 115.29g of phosphoric acid (85% phosphoric acid, 1mol), add 500g of water to dilute and dissolve, and prepare a phosphorus source solution with a mass fraction of solute of 15.9%;
  • Step S2 weighing 2 g of soluble starch, adding it to 10 g of water and boiling it for 30 min until there is no obvious white precipitate to obtain a colloid auxiliary agent;
  • Step S3 adding a colloidal auxiliary agent to the above transition metal salt solution to obtain a colloidal solution, and an obvious Tyndall effect can be observed;
  • Step S4 using 0.1 g of polyethylene glycol 4000 as a surfactant, weighing 207.32 g (1.5 mol) of potassium carbonate, adding 500 g of water to dissolve to obtain a breaker, adding the surfactant to a four-mouth glass reactor containing 100 mL of water, adding the breaker, the colloid liquid, and the above-mentioned lithium source solution and phosphorus source solution to the four-mouth glass reactor, stirring at a speed of 2000 rpm/min, under the protection of nitrogen, controlling the reaction temperature to 55° C., controlling the colloid liquid feed rate to about 0.5 g/min, and controlling the reaction pH to 4 to 12;
  • Step S5 After all the materials are added, the mixture is aged at 60° C. for 24 hours, and the precipitate is washed, filtered and dried at 100° C. in vacuum to obtain an iron-containing phosphate precursor.
  • the D50 of the obtained phosphate precursor is 1.6um, and the morphology is spherical, and the SEM is shown in Figure 1.
  • the XRD of the phosphate precursor is shown in Figure 2.
  • the mass of lithium in the phosphate precursor is The mass fraction is 3.4%, the mass ratio of lithium element to transition metal element in the phosphate precursor is 12.4%, and the mass ratio of lithium element to phosphorus element in the phosphate precursor is 22.4%.
  • the phosphate precursor was heated to 300° C. and heat treated for 48 hours, then cooled and ground to obtain a phosphate positive electrode material.
  • the phosphate cathode material is spherical, and the SEM is shown in Figure 3.
  • the XRD pattern of the phosphate cathode material conforms to the characteristic peaks (101), (111), (211), and (311) of lithium iron phosphate (PDF 81-1173), and has no impurity peaks, as shown in Figure 4.
  • Step S2 weighing 0.65 g of cationic polyacrylamide, stirring for 60 min at 40° C., and dispersing into 20 g of water to obtain colloid auxiliary agent-1; weighing 0.65 g of anionic polyacrylamide, stirring for 60 min at 40° C., and dispersing into 20 g of water to obtain colloid auxiliary agent-2;
  • Step S3 taking colloidal auxiliary agent-1 and adding it to the transition metal ion solution to obtain colloidal liquid-1, and an obvious Tyndall effect can be observed; taking colloidal auxiliary agent-2 and adding it to the lithium source solution to obtain colloidal liquid-2, and an obvious Tyndall effect can be observed;
  • Step S5 After all the materials are added, the mixture is aged at 60°C for 24 hours, and the precipitate is washed and filtered under the protection of nitrogen. The manganese-containing phosphate precursor precipitate is dried at 120° C. in vacuum to obtain a manganese-containing phosphate precursor.
  • the phosphate precursor was heated to 260° C. for heat treatment for 60 h, and then cooled and ground to obtain a phosphate positive electrode material.
  • the soluble transition metal salt in step S1 is 84.51 g of manganese sulfate monohydrate (0.5 mol) and 139.01 g of ferrous sulfate heptahydrate (0.5 mol).
  • the heat treatment temperature is 400°C and the heat treatment time is 12h.
  • the soluble transition metal salt in step S1 is 28.11 g of cobalt sulfate heptahydrate (0.1 mol) and 250.20 g of ferrous sulfate heptahydrate (0.9 mol).
  • the colloidal auxiliary agent in step S2 is methylcellulose.
  • the heat treatment temperature is 500°C and the heat treatment time is 12h.
  • the soluble transition metal salt in step S1 is 26.28 g nickel sulfate hexahydrate (0.1 mol) and 250.20 g ferrous sulfate heptahydrate (0.9 mol), and the soluble lithium salt is 42.39 g lithium chloride (1 mol).
  • the colloidal auxiliary agent is polypropylene alcohol.
  • the heat treatment temperature is 600°C and the heat treatment time is 8h.
  • the soluble lithium salt in step S1 is 42.39 g lithium chloride (1 mol)
  • the phosphorus-containing compound is 136.09 g monopotassium phosphate (1 mol)
  • the gel breaker in step S4 is 112.22 g potassium hydroxide (2 mol).
  • the heat treatment temperature is 600°C and the heat treatment time is 4 hours.
  • the difference from Example 1 is that in the preparation of the phosphate precursor, the soluble lithium salt in step S1 is 68.96 g lithium nitrate (1 mol).
  • the heat treatment temperature is 550°C and the heat treatment time is 8 hours.
  • Example 1 The difference from Example 1 is that in the preparation of the phosphate precursor, the phosphorus-containing compound in step S1 is 115.03 g of monoammonium phosphate (1 mol), and the gel breaker in step S4 is 152.03 g of potassium carbonate (1 mol).
  • the heat treatment temperature is 450°C and the heat treatment time is 20h.
  • the phosphorus-containing compound in step S1 is 149.09 g of triammonium phosphate (1 mol).
  • the gel breaker in step S4 is 13.82 g of potassium carbonate (0.1 mol).
  • Example 2 The difference from Example 1 is that in the preparation of the phosphate precursor, the solid content of the transition metal salt solution is 10%, the solid content of the lithium source solution is 4%, and the mass fraction of the phosphorus source solution is 5%.
  • Example 2 The difference from Example 1 is that: Preparation of positive electrode material: 10 g of phosphate precursor was mixed with 0.26 g of glucose monohydrate and ball-milled for 20 min, and the mixed powder was heated to 400° C. for 8 h in a nitrogen atmosphere, and then cooled and ground to obtain a carbon-doped positive electrode material, wherein the mass ratio of carbon element to lithium element was 22.8%.
  • Example 11 The difference from Example 11 is that the carbon source is 0.36 g of polyvinyl pyrrolidone, ball milled for 120 min, Heat to 600 degrees Celsius for 8 hours.
  • Example 11 The difference from Example 11 is that the carbon source is 0.20 g of carbon nanotubes, ball milling is performed for 120 min, and the temperature is raised to 350° C. for heat treatment for 30 h.
  • Example 11 The difference from Example 11 is that the carbon source is 0.15 g of graphite, and the ball milling is 180 min.
  • a method for preparing a phosphate positive electrode material which differs from Example 1 in that no colloidal auxiliary agent and surfactant are added.
  • a secondary battery comprises a negative electrode sheet, a separator, an electrolyte, a shell and the above-mentioned positive electrode sheet, wherein the separator is used to separate the negative electrode sheet and the positive electrode sheet, and the shell is used to install the positive electrode sheet, the electrolyte, the negative electrode sheet and the electrolyte.
  • positive electrode sheet The positive electrode material (phosphate positive electrode material or carbon-doped positive electrode material) prepared above, conductive agent superconducting carbon (Super-P), and binder polyvinylidene fluoride (PVDF) are mixed evenly in a mass ratio of 97:1.5:1.5 to prepare a lithium-ion battery positive electrode slurry with a certain viscosity, and the slurry is coated on the current collector aluminum foil, dried at 85°C and then cold pressed; then trimming, cutting, and striping are performed, and after stripping, it is dried at 110°C for 4 hours under vacuum conditions, and the pole ears are welded to make positive electrode sheets.
  • the positive electrode material phosphate positive electrode material or carbon-doped positive electrode material
  • Super-P conductive agent superconducting carbon
  • PVDF binder polyvinylidene fluoride
  • the negative electrode is a metal lithium sheet.
  • the electrolyte is 1 mol/L lithium hexafluorophosphate (LiPF 6 ) dissolved in a mixed solvent consisting of ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) (the mass ratio of the three is 1:1:1).
  • the separator is a Celgard 2400 microporous membrane.
  • Preparation of lithium-ion battery Assemble the above-mentioned positive electrode sheet, the above-mentioned negative electrode sheet, the electrolyte and the separator into a button battery in a glove box.

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Abstract

本发明属于二次电池技术领域，尤其涉及一种磷酸盐前驱体，所述磷酸盐前驱体的化学式为LixMy(PO4)(x+y)/2Az·wH2O，其中M为过渡金属元素，所述过渡金属元素为Fe、Ti、V、Cr、Ni、Co、Mn、Al、Nb、Y、Zr、Sb、Mo、Sn、Ce中的一种或多种，A为F-、OH-、CO3 2-、C2O4 2-、O2-中的一种或多种，其中0.5≤x＜1.2，0.5＜y≤1，0≤z≤1，0.1≤w＜8。本发明的一种磷酸盐前驱体，具有良好的均匀性，结构稳定性好，在260℃～600℃低温烧结的条件下即可制备得到橄榄石型的磷酸盐正极材料；磷酸盐前驱体掺杂碳源，热处理后获得的掺碳正极材料的电化学性能好。

Description

一种磷酸盐前驱体及其制备方法、正极材料及其制备方法、正极片和二次电池 技术领域
本发明属于二次电池技术领域，尤其涉及一种磷酸盐前驱体及其制备方法、正极材料及其制备方法、正极片和二次电池。
背景技术
目前二次锂离子电池用的磷酸盐正极材料主流的制备工艺可分为固相法和液相法两大路线。固相法多采用机械研磨的方式将原料混合，在惰性气氛保护下，经过700～850℃的高温反应，制备得到橄榄石型的磷酸盐正极材料。该方法的特点是操作简单，但此方法由于混合的原料不均匀，易发生偏析，造成产品的一致性较差，影响材料的电性能。且由于所需烧结温度高，工序较长等问题，造成能耗高，生产周期长。
液相反应比固相反应更容易使反应物混合均匀，利用反应原料在液相中的溶解性，可以制备纳米级甚至分子级别混合的材料。
常见液相法以水热法为主。水热法常见以硫酸亚铁、磷酸、氢氧化锂为原料，合成温度在140～210℃左右，压力为1.4MPa左右，反应时间约为3～24h。水热合成结束后，将物料过滤洗涤，真空干燥后得到磷酸铁锂，为提高电性能还可再进行碳包覆。通常最终产物具有良好的电化学性能，但该法的锂离子利用率低仅有1/3，原料成本过高，且产率低，需要高压设备，无法实现规模化生产。
专利《CN103259015B》中采用两步法，先制备Li3PO4，再用水热法制备磷酸铁锂，产物的颗粒均匀，一致性好。但该法的产率低，制备过程中需要高压，危险性高。特别是大型的耐高温高压反应器的设计制造难度大，造价高，难以实现规模化生产。
另一种制备磷酸盐正极材料的方法是溶胶凝胶法，可采用硝酸盐、醋酸盐 等易高温分解的原料，如Fe(NO3)2、H3PO4和LiCH3COO作为前驱体合成凝胶，然后在氮气氛围下600℃～700℃烧结4～24h后，即可得到LiFePO4粉体。但溶胶凝胶法原料成本高，难以实现工业应用。
专利《CN112086635A》中，使用碳酸锂、磷酸盐、硝酸铁、强氧化剂、强酸、聚合物单体等，采用自热蒸发法减少能耗，使聚合物单体的聚合与磷酸铁锂的晶核形成同时进行，以控制最终产品的形貌和粒径，获得一致性好的磷酸盐正极材料。该方法需要在700～780℃的高温的条件下，脱除硝酸铵等副产物，从而制备得到磷酸铁锂。该法制备的磷酸铁锂电化学性能较好，但制备过程中需要使用强氧化剂和强酸，具备较高的危险性。且利用高温脱除硝酸铵等副产物，过程中产生大量氮氧化物气体，污染环境，危险性高。
发明内容
本发明的目的之一在于：针对现有技术的不足，而提供一种磷酸盐前驱体，具有良好的均匀性，含有结晶水，结构稳定性好，在260℃～600℃低温烧结的条件下即可制备得到橄榄石型的磷酸盐正极材料，且正极材料的电化学性能好。
一种磷酸盐前驱体，所述磷酸盐前驱体的化学式为LixMy(PO4)(x+y)/2Az·wH2O，其中M为过渡金属元素，所述过渡金属元素为Fe、Ti、V、Cr、Ni、Co、Mn、Al、Nb、Y、Zr、Sb、Mo、Sn、Ce中的一种或多种，A为F-、OH-、CO3 2-、C2O4 2-、O2-中的一种或多种，其中0.5≤x＜1.2，0.5＜y≤1，0≤z≤1，0.1≤w＜8。优选地，所述过渡金属元素含Fe、Mn、Co中的一种或两种。
优选地，所述磷酸盐前驱体在铜靶kα1的2θ衍射角的XRD谱图中，存在特征峰F1：9.0°～11.5°，特征峰F2：22.1°～22.8°、特征峰F3：22.9°～23.5°、特征峰F4：24.5°～25.1°，所述特征峰F1与F3的比值为0.02～100。
优选地，所述磷酸盐前驱体中锂的质量分数为1％～5.3％，所述磷酸盐前驱体中锂元素与过渡金属元素的质量比为5.8％～30.3％，锂元素与磷元素的质 量比为14.8％～31.6％。
优选地，所述磷酸盐前驱体的颗粒粒径D50为0.05～20μm。
优选地，所述磷酸盐前驱体的形貌为球形、类球形、片层、条形中的一种或几种。
本发明的目的之二在于：针对现有技术的不足，而提供一种磷酸盐前驱体的制备方法，通过将胶体助剂加入过渡金属盐溶液或锂源溶液或磷源溶液三者中的至少一种及以上，制得胶体液；再混合搅拌胶体液和原料，在胶体体系下，发生多相沉淀，利用表面活性剂，和胶体液中的聚合物起的排斥作用，阻止胶体粒子聚沉，可使沉淀过程中不同粒子分布达到纳米、亚微米级别的混合状态；同时控制破胶剂的加入，打破胶体平衡，使不同粒子结合为沉淀；再将沉淀经过陈化，洗涤，干燥后，制得均匀性好的磷酸盐前驱体。
为了实现上述目的，本发明采用以下技术方案：
一种磷酸盐前驱体的制备方法，包括以下步骤：
步骤S1、将可溶性过渡金属盐分散于溶剂中得到过渡金属盐溶液，将可溶性锂盐分散于溶剂中得到锂源溶液，将含磷化合物分散于溶剂中得到磷源溶液；
步骤S2、将聚合物分散于溶剂中搅拌分散得到胶体助剂；
步骤S3、将胶体助剂加入到步骤S1中的过渡金属盐溶液或锂源溶液或磷源溶液三者中的至少一种及以上，得到胶体液；
步骤S4、将表面活性剂、破胶剂、步骤S3中的胶体液以及步骤S1中其余的溶液加入反应器中，控制温度，在气氛条件下，混合搅拌，发生多相沉淀反应，获得沉淀；
步骤S5、将步骤S4中的沉淀经过陈化，洗涤，干燥后得到磷酸盐前驱体。
优选地，所述步骤S1中过渡金属盐溶液的固含量为1.5％～30％，锂源溶液的固含量为1.1％～27％，磷源溶液的质量分数为1％～25％，所述步骤S1中过渡金属盐溶液包括Fe、Ti、V、Cr、Ni、Co、Mn、Al、Nb、Y、Zr、Sb、Mo、Sn、Ce金属元素中的一种或几种。
优选地，所述步骤S2中胶体助剂的制备方法为将聚合物加入溶剂中，加热至20℃～100℃，搅拌分散30～300分钟，所述聚合物占胶体助剂的重量份数为0.1％～20％，其中，所述聚合物为甲基纤维素、淀粉、聚丙烯酰胺、聚乙烯吡咯烷酮、聚丙烯醇、琼脂、卡拉胶、阿拉伯胶、瓜尔豆胶、罗望子胶中的一种或几种混合物。
优选地，所述步骤S3中所述聚合物占胶体液的重量份数为0.02％～2％，其中。
优选地，所述步骤S4中所述气氛条件为氮气、氩气或二氧化碳气氛。
优选地，所述步骤S5中所述的干燥的具体操作为在真空环境下加热至70℃～200℃烘干至恒重，或在空气环境中加热至100℃～200℃烘干至恒重，更优选地，在真空环境下加热至70℃～200℃烘干至恒重。
本发明的目的之三在于：针对现有技术的不足，而提供一种磷酸盐正极材料的制备方法，制备简单，使用较低温度进行热处理，能耗少，成本低，不产生氮氧化物类有毒有害气体，污染排放少，安全性好。
一种磷酸盐正极材料的制备方法，将上述的磷酸盐前驱体在氩气、氮气或氢氩混合气等无氧氛围下，加热至260℃～600℃，热处理2～72小时后降温。
本发明的目的之四在于：针对现有技术的不足，而提供一种磷酸盐正极材料，生产成本低，具有良好的性能和稳定性。
一种磷酸盐正极材料，由上述的磷酸盐正极材料的制备方法得到，所述的磷酸盐正极材料室温下0.1C放电比容量达到100～140mAh/g。
本发明的目的之五在于：针对现有技术的不足，而提供一种掺碳正极材料的制备方法，使用较低温度进行热处理，能耗少，成本更低，不产生氮氧化物类有毒有害气体，安全性好。
一种掺碳正极材料的制备方法，将上述的磷酸盐前驱体或磷酸盐正极材料与碳源混合，在氩气、氮气或氢氩混合气等无氧氛围下，加热至260℃～600℃，热处理2～72小时后降温。
优选地，所述碳源为葡萄糖、果糖、蔗糖、淀粉、石墨、石墨烯、碳纳米管、聚乙烯吡咯烷酮中的一种或多种。
本发明的目的之六在于：针对现有技术的不足，而提供一种掺碳正极材料，具有良好的电性能和稳定性。
一种掺碳正极材料，由上述的掺碳正极材料的制备方法得到，所述的掺碳正极材料室温下0.1C倍率放电比容量达到140～160mAh/g。
优选地，所述掺碳正极材料中碳元素与锂元素的质量比为11.4％～182.1％，所述碳元素的来源包括无定型碳、石墨、石墨烯、碳纳米管中的一种或多种。
本发明的目的之七在于：针对现有技术的不足，而提供一种正极片，具有良好的电化学性能。
一种正极片，包括正极集流体以及设置于正极集流体至少一表面的正极涂层，所述正极涂层包括上述的掺碳正极材料。
本发明的目的之八在于：针对现有技术的不足，而提供一种二次电池，具有良好的电化学性能。
一种二次电池，包括上述的正极片。
相对于现有技术，本发明的有益效果在于：本发明的一种磷酸盐前驱体，为水合物，具有良好的均匀性，结构稳定性好。在260℃～600℃低温烧结的条件下即可制备得到橄榄石型的磷酸盐正极材料，过程中不产生氮氧化物类有毒有害气体，且正极材料的电化学性能好。本发明的一种磷酸盐前驱体的制备方法，通过加入胶体助剂制得胶体液，在胶体体系下，发生多相沉淀，利用表面活性剂，和胶体液中的聚合物起的排斥作用，阻止胶体粒子聚沉，使沉淀过程中不同粒子分布达到纳米、亚微米级别的混合状态，再通过控制破胶剂的加入，打破胶体平衡，使不同粒子结合为沉淀，再将沉淀经过陈化，洗涤，干燥后，制得均匀性好的磷酸盐前驱体。
附图说明
图1是本发明实施例1的磷酸盐前驱体放大示意图。
图2是本发明实施例1的磷酸盐前驱体的XRD图。
图3是本发明实施例1热处理后得到的磷酸盐正极材料的放大示意图。
图4是本发明实施例1热处理后得到的磷酸盐正极材料的XRD图。
图5是对比例1热处理后得到的材料的XRD图。
图6是本发明实施例11、12得到的掺碳正极材料制成电池的放电曲线。
具体实施方式
下面结合具体实施方式和说明书附图，对本发明作进一步详细的描述，但本发明的实施方式并不限于此。
本发明的一种磷酸盐前驱体，所述磷酸盐前驱体的化学式为LixMy(PO4)(x+y)/2Az·wH2O，其中M为过渡金属元素，所述过渡金属元素为Fe、Ti、V、Cr、Ni、Co、Mn、Al、Nb、Y、Zr、Sb、Mo、Sn、Ce中的一种或多种，A为F-、OH-、CO3 2-、C2O4 2-、O2-中的一种或多种，其中0.5≤x＜1.2，0.5＜y≤1，0≤z≤1，0.1≤w＜8。本发明的磷酸盐前驱体为水合物，具有结合水。本发明的磷酸盐前驱体中过渡金属元素、锂元素、磷元素，三者均匀分布，形成稳定的结构，在260℃～600℃低温烧结的条件下即可制备得到正极材料，过程简单，能耗低。
在一些实施例中，所述磷酸盐前驱体在铜靶kα1的2θ衍射角的XRD谱图中，存在特征峰F1：9.0°～11.5°，特征峰F2：22.1°～22.8°、特征峰F3：22.9°～23.5°、特征峰F4：24.5°～25.1°，所述特征峰F1与F3的比值为0.02～100。
在一些实施例中，所述磷酸盐前驱体中锂的质量分数为1％～5.3％，所述磷酸盐前驱体中锂元素与过渡金属元素的质量比为5.8％～30.3％，锂元素与磷元素的质量比为14.8％～31.6％。优选地，磷酸盐前驱体中锂的质量分数为1％、1.2％、1.5％、1.7％、1.9％、2％、2.5％、3％、3.4％、4％、4.5％、5％、5.3％，所述磷酸盐前驱体中锂元素与过渡金属元素的质量比为6.2％、7.5％、8.7％、9.9％、11.1％、12.4％、13.6％、15.5％、17.7％、20.7％、24.8％、27.3％，锂元 素与磷元素的质量比为14.8％、16.8％、18.4％、19.9％、22.4％、24.4％、26.9％、29.9％。
在一些实施例中，所述过渡金属元素为锰。
在一些实施例中，所述过渡金属元素为铁。
在一些实施例中，所述过渡金属元素为铁和锰，其中铁元素与总过渡金属元素的质量比≥0.1。
在一些实施例中，所述磷酸盐前驱体的颗粒粒径D50为0.05～20μm。优选地，磷酸盐前驱体的颗粒粒径D50为0.05μm、0.1μm、0.5μm、0.9μm、1μm、1.6um、3um、4μm、8μm、10μm、15μm、18μm、19μm、20μm。
在一些实施例中，所述磷酸盐前驱体的形貌为球形、类球形、片层、条形中的一种或几种。
本发明的一种磷酸盐前驱体的制备方法，包括以下步骤：
步骤S1、将可溶性过渡金属盐分散于溶剂中得到过渡金属盐溶液，将可溶性锂盐分散于溶剂中得到锂源溶液，将含磷化合物分散于溶剂中得到磷源溶液；
步骤S2、将聚合物分散于溶剂中搅拌分散得到胶体助剂；
步骤S3、将胶体助剂加入到步骤S1中的过渡金属盐溶液或锂源溶液或磷源溶液三者中的至少一种及以上，得到胶体液；
步骤S4、将步骤S3中的胶体液、表面活性剂、破胶剂以及步骤S1中其余的溶液加入反应器中，控制温度，在气氛条件下，混合搅拌，发生多相沉淀；
步骤S5、将步骤S4中的沉淀经过陈化，洗涤，干燥后得到磷酸盐前驱体。
本发明的一种磷酸盐前驱体的制备方法，通过将胶体助剂加入过渡金属盐溶液、锂源溶液或磷源溶液三者中的至少一种及以上，制得胶体液；再混合搅拌胶体液和原料，在胶体体系下，发生多相沉淀，利用表面活性剂，和胶体液中的聚合物起的排斥作用，阻止胶体粒子聚沉，可使沉淀过程中不同粒子分布达到纳米、亚微米级别的混合状态；通过控制破胶剂的加入，打破胶体平衡，使不同粒子结合为沉淀；再将沉淀经过陈化，洗涤，干燥后，制得均匀性好的 磷酸盐前驱体。
其中，溶剂为水、乙醇或异丙醇。其中，气氛条件为氩气、氮气或氢氩混合气中的一种无氧氛围。
可溶性过渡金属盐的阳离子为Fe、Ti、V、Cr、Ni、Co、Mn、Al、Nb、Y、Zr、Sb、Mo、Sn、Ce原子失去一个或多个电子形成的离子中的一种或多种，阴离子可为SO4 2-、SO3 2-、NO3 -、Cl-、CH3COO-、C6H5O7 3-中的一种或多种。优选地，所述可溶性过渡金属盐为铁盐、锰盐、钴盐中的一种或多种，铁盐包括硫酸亚铁、氯化亚铁、硝酸亚铁、醋酸亚铁、亚硫酸铁、硫酸铁、氯化铁、硝酸铁中的一种或几种，锰盐包括硫酸锰、硝酸锰、氯化锰、醋酸锰、柠檬酸锰、亚硫酸锰中的一种或几种，钴盐包括硫酸钴、硝酸钴、氯化钴、醋酸钴、柠檬酸钴、亚硫酸钴中的一种或几种。
可溶性锂盐包括草酸锂，硫酸锂、氯化锂、硝酸锂、亚硫酸锂、氯酸锂、高氯酸锂、溴化锂、溴酸锂、碘化锂、硫氰酸锂、亚硝酸锂、甲酸锂、醋酸锂、柠檬酸锂中的一种或多种。
含磷化合物包括磷酸、磷酸一铵、磷酸二铵、磷酸三胺、磷酸一钠、磷酸二钠、磷酸三钠中的一种或多种。
胶体助剂包括甲基纤维素、淀粉、聚丙烯酰胺、聚乙烯吡咯烷酮、聚丙烯醇、聚丙烯腈、琼脂、卡拉胶、阿拉伯胶、瓜尔豆胶、罗望子胶中的一种或几种混合物。表面活性剂包括聚乙二醇、CTAB、脂肪醇聚氧乙烯醚、脂肪酸聚氧乙烯酯、烷基多糖苷、烷基醇酰胺、乙氧基化失水山梨醇脂肪酸酯等中的一种或多种。破胶剂包括氢氧化钠、碳酸钠、碳酸氢钠、氨水、碳酸铵、碳酸氢铵、氢氧化锂、碳酸锂、碳酸氢锂、氢氧化钾、碳酸钾、碳酸氢钾中的一种或多种。破胶剂的固含量为1％～16％，优选地，破胶剂的固含量为1％、5％、8％、9％、10％、14％、15％、15.5％、16％。
在一些实施例中，所述过渡金属盐溶液的固含量为1.5％～30％，锂源溶液的固含量为1.1％～27％，磷源溶液的质量分数为1％～25％。优选地，过渡金属 盐溶液的固含量为1.5％～10％、10％～20％、20％～30％，具体地，过渡金属盐溶液的固含量为1.5％、4％、5％、8％、10％、15％、18％、20％、24％、27％、29％、30％，优选地，锂源溶液的固含量为1.1％～10％、10％～15％、15％～20％、20％～27％，具体地，锂源溶液的固含量为1.1％、4％、5％、8％、10％、15％、18％、20％、24％、27％，优选地，磷源溶液的质量分数为1％～10％、10％～15％、15％～20％、20％～25％，具体地，磷源溶液的质量分数为1.5％、4％、5％、8％、10％、15％、18％、20％、24％、25％。过渡金属盐溶液、锂源溶液、磷源溶液设置一定的固含量，使进行反应时更充分，反应更均匀，制备得到的磷酸盐前驱体性能更好。
在一些实施例中，所述步骤S2中胶体助剂的制备方法为将聚合物加入溶剂中，加热至20℃～100℃，搅拌分散30～300分钟。优选地，加热温度为20℃～40℃、40℃～60℃、60℃～80℃、80℃～100℃，具体地，加热温度为20℃、30℃、40℃、50℃、60℃、70℃、80℃、90℃、100℃，搅拌分散时间为30～60分钟、60～120分钟、120～300分钟，具体地，搅拌分散时间为30分钟、60分钟、90分钟、120分钟、180分钟、300分钟。
在一些实施例中，聚合物占胶体助剂的重量份数为0.1％～20％，所述聚合物为甲基纤维素、淀粉、聚丙烯酰胺、聚乙烯吡咯烷酮、聚丙烯醇、琼脂、卡拉胶、阿拉伯胶、瓜尔豆胶、罗望子胶中的一种或几种混合物。优选地，聚合物占胶体助剂的重量份数为0.1％～8％、8％～16％、16％～20％，具体地，聚合物占胶体助剂的重量份数为0.1％、2％、5％、8％、10％、11％、14％、15％、16％、18％、20％；
在一些实施例中，所述步骤S3中，所述聚合物占胶体液的重量份数为0.02％～2％，优选地，聚合物占胶体液的重量份数为0.02％～1％、1％～2％，具体地，聚合物占胶体液的重量份数为0.02％、0.08％、0.1％、0.2％、0.8％、0.86％、1％、1.2％、1.6％、1.8％、1.9％、2％。
在一些实施例中，所述步骤S4中所述的合成过程中需要通入氮气、氩气、 二氧化碳气体进行保护，防止材料氧化，以避免沉淀过程中，元素比例发生偏析。
在一些实施例中，所述步骤S5中所述的干燥的具体操作为在真空环境下加热至70℃～200℃烘干至恒重，或在空气环境中加热至100℃～200℃烘干至恒重，优选地，在真空环境下加热至70℃～200℃烘干至恒重。通过干燥，去除材料中的自由水分，得到含有结晶水的产物，稳定性好。
一种磷酸盐正极材料的制备方法，将上述的磷酸盐前驱体在氩气、氮气或氢氩混合气等无氧氛围下，加热至260℃～600℃，热处理2～72小时后降温。优选地，加热温度可为260℃、280℃、300℃、350℃、400℃、450℃、500℃、550℃、600℃。热处理时间可为4小时、8小时、10小时、16小时、24小时、30小时、36小时、48小时、50小时、60小时、72小时。
一种磷酸盐正极材料，由上述的磷酸盐正极材料的制备方法得到。所述磷酸盐正极材料制成锂离子电池后，室温下0.1C放电比容量达到100～130mAh/g。
一种掺碳正极材料的制备方法，将磷酸盐前驱体与碳源混合，在氩气、氮气或氢氩混合气等无氧氛围下，加热至260℃～600℃，热处理2～72小时得到。所述碳源为葡萄糖、果糖、蔗糖、淀粉、石墨、石墨烯、碳纳米管、聚乙烯吡咯烷酮中的一种或多种。加热温度为260℃、300℃、350℃、380℃、400℃、420℃、450℃、480℃、500℃、550℃、600℃。反应时间2小时、4小时、6小时、8小时、12小时、15小时、18小时、20小时、25小时、29小时、32小时、37小时、39小时、40小时、43小时、46小时、48小时、50小时、55小时、60小时、65小时、70小时、72小时。
所述的掺碳正极材料中碳元素与锂元素的质量比为11.4％～182.1％，所述C元素的组成可以为无定型碳、石墨、石墨烯、碳纳米管中的一种或几管，优选，无定型碳、碳纳米管。所述的掺碳正极材料制成锂离子电池后，室温下0.1C倍率放电比容量达到140～160mAh/g。
一种掺碳正极材料，由上述的掺碳正极材料的制备方法得到，具有良好的 电性能和稳定性。
一种正极片，包括正极集流体以及设置于正极集流体至少一表面的正极涂层，所述正极涂层包括上述的掺碳正极材料。本发明的正极片具有良好的电化学性能。
一种二次电池，包括上述的正极片。
实施例1
磷酸盐前驱体的制备：
步骤S1、称量278.01g七水硫酸亚铁(1mol)，加入500g水搅拌溶解，制得过渡金属盐溶液，固含量为19.5％；称量草酸锂50.95g(0.5mol)，加水700g溶解，配制锂液，固含量为12.7％；称量磷酸115.29g(85％磷酸，1mol)，加水500g水稀释溶解，制得磷源溶液，溶质的质量分数为15.9％；
步骤S2、称量2g可溶性淀粉，加入10g水中煮沸30min，至无明显白色沉淀得到胶体助剂；
步骤S3、将胶体助剂加入上述过渡金属盐溶液中得到胶体液，可观察到明显的丁达尔效应；
步骤S4、将0.1g聚乙二醇4000作为表面活性剂，称量碳酸钾207.32g(1.5mol)，加入500g水溶解得到破胶剂，将表面活性剂加入到含100mL水的四口玻璃反应器中，将破胶剂、胶体液以及上述的锂源溶液、磷源溶液加入到四口玻璃反应器中，搅拌速度为2000rpm/min，在氮气的保护下，控制反应温度为55℃，控制胶体液进料速度约0.5g/min，控制反应pH为4～12；
步骤S5、全部加料结束后，60℃陈化24小时，在氮气的保护下，洗涤过滤沉淀，在真空100℃下干燥得到含铁的磷酸盐前驱体。
所得磷酸盐前驱体的D50为1.6um，形貌为类球形，SEM如图1所示。磷酸盐前驱体的XRD如图2所示，存在特征峰F1：9.0°～11.5°，特征峰F2：22.1°～22.8°、特征峰F3：22.9°～23.5°、特征峰F4：24.5°～25.1°，其中特征峰F1与F3的比值为2.78。经元素成分分析，磷酸盐前驱体中锂元素的质 量分数为3.4％，磷酸盐前驱体中锂元素与过渡金属元素的质量比为12.4％，磷酸盐前驱体中锂元素与磷元素的质量比为22.4％。
正极材料的制备：
在氮气氛围下，将磷酸盐前驱体升温至300℃热处理48h，然后冷却后，经研磨得到磷酸盐正极材料。
磷酸盐正极材料为类球形，SEM如图3所示。磷酸盐正极材料的XRD图符合磷酸铁锂(PDF 81-1173)的特征峰(101)、(111)、(211)、(311)，且无杂峰，如图4所示。
实施例2
磷酸盐前驱体的制备：
步骤S1、称量169.01一水硫酸锰(1mol)，加入500g水搅拌溶解，制得过渡金属盐溶液，固体含量为22.6％；称量43.26g一水氢氧化锂(wt＝0.97，1mol)，加水500g溶解，制得锂源溶液，固体含量为4.4％；称量156.01g二水磷酸一钠(1mol)，加水500g水溶解，制得磷源溶液，溶质的质量分数为18.3％；
步骤S2、称量0.65g阳离子聚丙烯酰胺，40℃条件下，搅拌60min，分散到20g水中，获得胶体助剂-1；称量0.65g阴离子聚丙烯酰胺，40℃条件下，搅拌60min，分散到20g水中，获得胶体助剂-2；
步骤S3、取胶体助剂-1加入到过渡金属离子液中，获得胶体液-1，可观察到明显的丁达尔效应；取胶体助剂-2加入到锂源溶液中，获得胶体液-2，可观察到明显的丁达尔效应；
步骤S4、将0.2g聚乙二醇4000作为表面活性剂，称量53.80g碳酸钠(wt＝0.985，0.5mol)加入500g水中溶解得到破胶剂，将表面活性剂加入到含100mL水的四口玻璃反应器中，将破胶剂、胶体液-1、胶体液-2以及上述的磷源溶液加入到四口玻璃反应釜中，搅拌速度为1800rpm，控制反应温度为50℃，控制胶体液-1的进料速度约0.5g/min，控制反应pH为7～13；
步骤S5、全部加料结束后，60℃陈化24h，在氮气的保护下，洗涤过滤沉 淀，真空120℃干燥含锰的磷酸盐前驱体沉淀，获得含锰的磷酸盐前驱体。
正极材料的制备：
在氩气氛围下，将磷酸盐前驱体升温至260℃热处理60h，然后冷却后，经研磨得到磷酸盐正极材料。
实施例3
与实施例1的区别在于：磷酸盐前驱体的制备中步骤S1中可溶性过渡金属盐为84.51g一水硫酸锰(0.5mol)和139.01g七水硫酸亚铁(0.5mol)。
正极材料的制备中热处理温度为400℃，热处理时间为12h。
其余与实施例1相同，这里不再赘述。
实施例4
与实施例1的区别在于：磷酸盐前驱体的制备中步骤S1中可溶性过渡金属盐为28.11g七水硫酸钴(0.1mol)和250.20g七水硫酸亚铁(0.9mol)。步骤S2中胶体助剂为甲基纤维素。
正极材料的制备中热处理温度为500℃，热处理时间为12h。
其余与实施例1相同，这里不再赘述。
实施例5
与实施例1的区别在于：磷酸盐前驱体的制备中步骤S1中可溶性过渡金属盐为26.28g六水硫酸镍(0.1mol)和250.20g七水硫酸亚铁(0.9mol)，可溶性锂盐为42.39g氯化锂(1mol)。步骤S2中胶体助剂为聚丙烯醇。
正极材料的制备中热处理温度为600℃，热处理时间为8h。
其余与实施例1相同，这里不再赘述。
实施例6
与实施例1的区别在于：磷酸盐前驱体的制备中步骤S1中可溶性锂盐为42.39g氯化锂(1mol)，含磷化合物为136.09g磷酸一钾(1mol)。步骤S4中破胶剂为112.22g氢氧化钾(2mol)
正极材料的制备中热处理温度为600℃，热处理时间为4h。
其余与实施例1相同，这里不再赘述。
实施例7
与实施例1的区别在于：磷酸盐前驱体的制备中步骤S1中可溶性锂盐为68.96g硝酸锂(1mol)。
正极材料的制备中热处理温度为550℃，热处理时间为8h。
其余与实施例1相同，这里不再赘述。
实施例8
与实施例1的区别在于：磷酸盐前驱体的制备中步骤S1中含磷化合物为115.03g磷酸一铵(1mol)。步骤S4中破胶剂为152.03碳酸钾(1mol)。
正极材料的制备中热处理温度为450℃，热处理时间为20h。
其余与实施例1相同，这里不再赘述。
实施例9
与实施例1的区别在于：磷酸盐前驱体的制备中步骤S1中含磷化合物为149.09g磷酸三铵(1mol)。步骤S4中破胶剂为13.82碳酸钾(0.1mol)
其余与实施例3相同，这里不再赘述。
实施例10
与实施例1的区别在于：磷酸盐前驱体的制备中所述过渡金属盐溶液的固含量为10％，锂源溶液的固含量为4％，磷源溶液的质量分数为5％。
其余与实施例3相同，这里不再赘述。
实施例11
与实施例1的区别在于：正极材料的制备：取磷酸盐前驱体10g，混合一水葡萄糖0.26g球磨20min，在氮气氛围下，将混合后的粉末升温至400℃热处理8h，然后冷却后，经研磨得到掺碳正极材料。其中碳元素与锂元素的质量比为22.8％。
实施例12
与实施例11的区别在于：所述碳源为聚乙烯吡咯烷酮0.36g，球磨120min， 升温至600摄氏度热处理8h。
其余与实施例11相同，这里不再赘述。
实施例13
与实施例11的区别在于：所述碳源为碳纳米管0.20g，球磨120min，升温至350℃热处理30h。
其余与实施例11相同，这里不再赘述。
实施例14
与实施例11的区别在于：所述碳源为石墨0.15g，球磨180min。
其余与实施例11相同，这里不再赘述。
对比例1——未加入胶体助剂和表面活性剂
一种磷酸盐正极材料的制备方法，其与实施例1的区别在于：未加入胶体助剂和表面活性剂。
其余与实施例1相同，这里不再赘述。
因未加入胶体助剂和表面活性剂，对比例1多相沉淀过程中发生沉淀的偏析，获得的前驱体经过升温至相同的300℃热处理48h，然后冷却后，经研磨得到正极材料未形成良好的磷酸铁锂结晶。对比例1热处理后得到的正极材料的XRD图如图5所示，无明显的磷酸铁锂的特征峰(101)、(111)、(211)、(311)。
一种二次电池，包括负极片、隔离膜、电解液、壳体以及上述的正极片，隔离膜用于分隔负极片和正极片，所述壳体用于装设正极片、电解液、负极片以及电解液。
正极片的制备：将上述制备得到的正极材料(磷酸盐正极材料或掺碳正极材料)、导电剂超导碳(Super-P)、粘结剂聚偏氟乙烯(PVDF)按质量比97：1.5：1.5混合均匀制成具有一定粘度的锂离子电池正极浆料，将浆料涂布在集流体铝箔上，在85℃下烘干后进行冷压；然后进行切边、裁片、分条，分条后在真空条件下以110℃烘干4小时，焊接极耳，制成正极片。
负极片为金属锂片。电解液为1mol/L六氟磷酸锂(LiPF6)溶解于碳酸乙烯酯(EC)、碳酸二甲酯(DMC)以及碳酸甲乙酯(EMC)组成的混合溶剂中(三者的质量比为1：1：1)。隔膜为Celgard 2400微孔膜。
锂离子电池的制备：在手套箱中将上述正极片、上述负极片、电解液和隔膜组装成扣式电池。
性能测试将实施例1-14以及对比例1得到的材料，应用于正极片和二次电池，进行0.1C和1C充放电性能测试，充电终止电压为4.2V，放电截止电压为2.0V。由实施例11、12的掺碳正极材料制得的扣式电池在0.1C倍率下的充放电曲线如图6。测试结果记录表1。
表1
由上述表1可以得出，本发明的制备出的二次电池相对于对比例1的二次电池的充放电容量具有较大的提升，充放电性能较为稳定。
根据上述说明书的揭示和教导，本发明所属领域的技术人员还能够对上述实施方式进行变更和修改。因此，本发明并不局限于上述的具体实施方式，凡是本领域技术人员在本发明的基础上所作出的任何显而易见的改进、替换或变型均属于本发明的保护范围。此外，尽管本说明书中使用了一些特定的术语，但这些术语只是为了方便说明，并不对本发明构成任何限制。

Claims (16)

  1. 一种磷酸盐前驱体，其特征在于：所述磷酸盐前驱体的化学式为LixMy(PO4)(x+y)/2Az·wH2O，其中M为过渡金属元素，所述过渡金属元素为Fe、Ti、V、Cr、Ni、Co、Mn、Al、Nb、Y、Zr、Sb、Mo、Sn、Ce中的一种或多种，A为F-、OH-、CO3 2-、C2O4 2-、O2-中的一种或多种，其中0.5≤x＜1.2，0.5＜y≤1，0≤z≤1，0.1≤w＜8。
  2. 根据权利要求1所述的磷酸盐前驱体，其特征在于：所述磷酸盐前驱体的铜靶kα1的2θ衍射角的XRD谱图中，存在特征峰F1：9.0°～11.5°，特征峰F2：22.1°～22.8°、特征峰F3：22.9°～23.5°、特征峰F4：24.5°～25.1°，所述特征峰F1与F3的比值为0.02～100。
  3. 根据权利要求1或2所述的磷酸盐前驱体，其特征在于：所述磷酸盐前驱体中锂的质量分数为1％～5.3％，所述磷酸盐前驱体中锂元素与过渡金属元素的质量比为5.8％～30.3％，锂元素与磷元素的质量比为14.8％～31.6％。
  4. 根据权利要求1或2所述的磷酸盐前驱体，其特征在于：所述磷酸盐前驱体的颗粒粒径D50为0.05～20μm。
  5. 根据权利要求1或2所述的磷酸盐前驱体，其特征在于：所述磷酸盐前驱体的形貌为球形、类球形、片层、条形中的一种或几种。
  6. 根据权利要求1～5中任一项所述的磷酸盐前驱体的制备方法，其特征在于：包括以下步骤：
    步骤S1、将可溶性过渡金属盐分散于溶剂中得到过渡金属盐溶液，将可溶性锂盐分散于溶剂中得到锂源溶液，将含磷化合物分散于溶剂中得到磷源溶液；
    步骤S2、将聚合物分散于溶剂中搅拌分散得到胶体助剂；
    步骤S3、将胶体助剂加入到步骤S1中的过渡金属盐溶液或锂源溶液或磷源溶液三者中的至少一种及以上，得到胶体液；
    步骤S4、将表面活性剂、破胶剂、步骤S3中的胶体液以及步骤S1中其余的溶液加入反应器中，控制温度，在气氛条件下，混合搅拌，发生多相沉淀反应，获得沉淀；
    步骤S5、将步骤S4中的沉淀经过陈化，洗涤，干燥后得到磷酸盐前驱体。
  7. 根据权利要求6所述的磷酸盐前驱体的制备方法，其特征在于：所述步骤S1中过渡金属盐溶液的固含量为1.5％～30％，锂源溶液的固含量为1.1％～27％，磷源溶液中溶质的质量分数为1％～25％，所述过渡金属盐溶液中包括Fe、Ti、V、Cr、Ni、Co、Mn、Al、Nb、Y、Zr、Sb、Mo、Sn、Ce金属元素中的一种或几种。
  8. 根据权利要求6所述的磷酸盐前驱体的制备方法，其特征在于：所述步骤S2中胶体助剂的制备方法为将聚合物加入溶剂中，加热至20℃～100℃，搅拌分散30～300分钟，所述聚合物占胶体助剂的重量份数为0.1％～20％，所述步骤S3中所述聚合物占胶体液的重量份数为0.02％～2％，其中，所述聚合物为甲基纤维素、淀粉、聚丙烯酰胺、聚乙烯吡咯烷酮、聚丙烯醇、琼脂、卡拉胶、阿拉伯胶、瓜尔豆胶、罗望子胶中的一种或几种混合物。
  9. 根据权利要求6所述的磷酸盐前驱体的制备方法，其特征在于：所述步骤S4中所述气氛条件为氮气、氩气或二氧化碳气氛，所述步骤S5中所述的干燥的具体操作为在真空环境下加热至70℃～200℃烘干至恒重，或在空气环境中加热至100℃～200℃烘干至恒重。
  10. 一种磷酸盐正极材料的制备方法，其特征在于，将权利要求1～5中任一项所述的磷酸盐前驱体在无氧氛围下，加热至260℃～600℃，热处理2～72小时后降温。
  11. 一种磷酸盐正极材料，其特征在于，由权利要求10所述的磷酸盐正极材料的制备方法得到。
  12. 一种掺碳正极材料的制备方法，其特征在于：将权利要求1～5中任一项所述的磷酸盐前驱体与碳源混合，在无氧氛围下，加热至260℃～600℃，热处理2～72小时，所述碳源为葡萄糖、果糖、蔗糖、淀粉、石墨、石墨烯、碳纳米管、聚乙烯吡咯烷酮中的一种或多种。
  13. 一种掺碳正极材料，其特征在于，由权利要求12中所述的掺碳正极 材料的制备方法得到。
  14. 根据权利要求13所述的掺碳正极材料，其特征在于，所述掺碳正极材料中碳元素与锂元素的质量比为11.4％～182.1％，所述碳元素的来源包括无定型碳、石墨、石墨烯、碳纳米管中的一种或多种。
  15. 一种正极片，其特征在于：包括正极集流体以及设置于正极集流体至少一表面的正极涂层，所述正极涂层包括权利要求13或14所述的掺碳正极材料。
  16. 一种二次电池，其特征在于：包括权利要求15所述的正极片。
PCT/CN2023/126835 2022-11-16 2023-10-26 一种磷酸盐前驱体及其制备方法、正极材料及其制备方法、正极片和二次电池 WO2024104075A1 (zh)

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