WO2025260808A1 - 一种含锂磷酸盐材料、锂离子电池正极及制备方法与应用 - Google Patents

一种含锂磷酸盐材料、锂离子电池正极及制备方法与应用

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Publication number
WO2025260808A1
WO2025260808A1 PCT/CN2025/078635 CN2025078635W WO2025260808A1 WO 2025260808 A1 WO2025260808 A1 WO 2025260808A1 CN 2025078635 W CN2025078635 W CN 2025078635W WO 2025260808 A1 WO2025260808 A1 WO 2025260808A1
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Prior art keywords
lithium
lithium phosphate
positive electrode
sized particles
sintering
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Pending
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PCT/CN2025/078635
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English (en)
French (fr)
Inventor
佘雪锋
何科峰
庄明昊
程斌
邓若燚
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BYD Co Ltd
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BYD Co Ltd
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Publication of WO2025260808A1 publication Critical patent/WO2025260808A1/zh
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • C—CHEMISTRY; METALLURGY
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/136—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
    • H01M4/13—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
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
    • 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

Definitions

  • This disclosure relates to the field of lithium-ion battery technology, specifically to a lithium phosphate material, a lithium-ion battery cathode, its preparation method, and its application.
  • Lithium iron phosphate ( LiFePO4 ) has advantages such as good structural stability, high safety, and good cycle performance as a cathode material for lithium batteries, and has been widely used in lithium-ion batteries for the power units of new energy vehicles.
  • Lithium manganese iron phosphate cathode material ( LiMnxFe1 -xPO4 , 0 ⁇ x ⁇ 1) is a novel material formed by partially replacing iron in LiFePO4 cathode material with manganese. This doping improves the voltage plateau of LiFePO4 and further enhances its energy density, thus attracting significant research attention.
  • Lithium iron phosphate (LFP) materials suffer from slow electron/ion conductivity. Nanoparticle modification is a crucial technique for improving this conductivity. Using nano-sized LFP particles increases the specific surface area of the cathode material, allowing for better contact between the electrolyte and the cathode, increasing reactive sites, significantly shortening the Li + transport distance, and improving the battery's reversible capacity and rate performance. However, nano-sized LFP particles have high surface energy, making them prone to agglomeration and difficult to disperse evenly in the slurry during electrode preparation. Furthermore, the increased specific surface area of the nano-sized cathode material makes it highly absorbent of water.
  • the purpose of this disclosure is to provide a lithium phosphate material, a lithium-ion battery cathode, a preparation method, and an application.
  • This lithium phosphate material can provide a large number of reactive sites, and the material has a suitable specific surface area and water absorption. When used in lithium-ion batteries, it can provide sufficient lithium-ion transport channels, thereby improving the reversible capacity and rate performance of the battery while reducing the risk of gelation.
  • the first aspect of this disclosure provides a lithium phosphate material, the lithium phosphate material comprising lithium phosphate micron-sized particles with pores on the surface, wherein lithium phosphate nanon-sized particles are embedded within the pores of the lithium phosphate micron-sized particles.
  • the ratio of the D50 particle size of the lithium phosphate micron-sized particles to the D50 particle size of the lithium phosphate nano-sized particles is 5 to 10.
  • the ratio of the D50 pore size of the channels of the lithium phosphate micron-sized particles to the D50 particle size of the lithium phosphate nano-sized particles is 0.8 to 1.
  • the D50 particle size of the lithium phosphate nanoparticles is 0.5–0.9 ⁇ m.
  • the D50 particle size of the lithium phosphate micron-sized particles is 2.5 to 10 ⁇ m, and the D50 pore size of the channels is 0.4 to 0.9 ⁇ m.
  • the porosity of the lithium phosphate-containing material is 10-15%.
  • the lithium phosphate micron-sized particles have a composition represented by the chemical formula LiAxB1 -xPO4 , wherein A is one or more of Ti, V, Mn, Fe, Co and Ni, B is one or more of Ti, V, Mn, Fe, Co and Ni, and x is any value between 0 and 1;
  • the lithium phosphate nanoparticles have a composition represented by the chemical formula LiA′ y B′ 1-y PO 4 , wherein A′ is one or more of Ti, V, Mn, Fe, Co and Ni, B′ is one or more of Ti, V, Mn, Fe, Co and Ni, and y is any value between 0 and 1.
  • a second aspect of this disclosure provides a method for preparing a lithium phosphate material, the method comprising the following steps:
  • the second lithium source, the second metal source, and the second phosphorus source are mixed, and the resulting mixture is subjected to a second pre-sintering to obtain a second pre-sintered product; the second pre-sintered product and the second carbon source are subjected to a second secondary sintering, and the second secondary sintered product is subjected to a second crushing treatment or a second granulation treatment to obtain lithium phosphate nanoparticles.
  • the first metal source and the second metal source are each independently a compound containing one or more elements selected from Ti, V, Mn, Fe, Co and Ni; the first carbon source and the second carbon source are each independently selected from one or more of sucrose, glucose, citric acid, phenolic resin, starch and carbon black.
  • the mass of the pore-forming agent accounts for 1 to 5% of the total mass of the first pre-sintered product and the pore-forming agent; the pore-forming agent is selected from one or more of ethanol, oxalic acid, ammonium bicarbonate, ammonium carbonate, urea and ammonium chloride.
  • the conditions for the first pre-sintering include: being carried out under a protective gas, a pre-sintering temperature of 500-650°C, and a pre-sintering time of 2-6 hours;
  • the conditions for the first and second sintering include: being carried out under a protective gas, a sintering temperature of 710–900°C, and a sintering time of 6–12 hours;
  • the conditions for the first crushing process include: crushing the first secondary sintering product using a ball mill, with a ball mill speed of 400-500 r/min and a ball milling time of 8-10 h;
  • the conditions for the first granulation process include: feed gas pressure of 0.8–1.2 MPa, inert protective gas flow rate of 30–50 L/min, gas preheating temperature of 100–150 °C, and feed solid content of 45–55%.
  • the conditions for the second pre-sintering include: being carried out under a protective gas, a pre-sintering temperature of 500-650°C, and a pre-sintering time of 2-6 hours;
  • the conditions for the second and third sintering include: being carried out under a protective gas, a sintering temperature of 600-700°C, and a sintering time of 4-8 hours;
  • the conditions for the second crushing process include: crushing the second secondary sintering product using a ball mill, with a ball mill speed of 450-600 r/min and a ball milling time of 10-15 h;
  • the conditions for the second granulation process include: feed gas pressure of 1-1.5 MPa, inert protective gas flow rate of 40-60 L/min, gas preheating temperature of 100-150 °C, and feed solid content of 45-55%.
  • step (2) the mixing is a solid-phase mixing and is carried out under stirring conditions, the stirring rate is 500 to 1200 rpm, the mixing temperature is 25 to 35°C, and the mixing time is 30 to 60 min.
  • the D50 particle size of the lithium phosphate nanoparticles is 0.5 to 0.9 ⁇ m; the D50 particle size of the lithium phosphate micron-sized particles is 2.5 to 10 ⁇ m; and the D50 particle size of the lithium phosphate micron-sized particles is 5 to 10 times that of the lithium phosphate nanoparticles.
  • the third aspect of this disclosure provides a lithium phosphate material prepared by the preparation method described in the second aspect of this disclosure.
  • the fourth aspect of this disclosure provides a method for preparing a positive electrode for a lithium-ion battery, the method comprising: mixing a lithium phosphate material, a conductive agent, a binder and a solvent to form a positive electrode slurry; forming a positive electrode slurry layer on a positive electrode current collector; removing the solvent from the positive electrode slurry layer to form a positive electrode sheet containing a positive electrode material layer;
  • the lithium-containing phosphate material is the lithium-containing phosphate material described in the first aspect and/or the third aspect of this disclosure.
  • the method further includes: shearing the positive electrode slurry before forming the positive electrode slurry layer, wherein the shearing conditions include: a shearing rate of 4000 to 8000 rpm and a shearing temperature of 20 to 35°C.
  • the mass ratio of the lithium phosphate micron-sized particles to the lithium phosphate nano-sized particles is 1:(50-200).
  • the fifth aspect of this disclosure provides a lithium-ion battery cathode prepared by the method described in the fourth aspect of this disclosure.
  • the sixth aspect of this disclosure provides a positive electrode for a lithium-ion battery, the positive electrode comprising a current collector and a positive electrode material layer disposed on at least one side of the current collector; the positive electrode material layer contains a lithium phosphate material; wherein the lithium phosphate material is the lithium phosphate material described in the first aspect and/or the third aspect of this disclosure.
  • the porosity of the positive electrode material layer is 15-25%.
  • the positive electrode material layer further contains positive electrode material nanoparticles
  • the cathode material nanoparticles have a chemical composition represented by the chemical formula LiA′′ z B′′ 1-z PO 4 , wherein A′′ is one or more of Ti, V, Mn, Fe, Co and Ni, B′′ is one or more of Ti, V, Mn, Fe, Co and Ni, and z is any value between 0 and 1.
  • the mass ratio of the cathode material nanoparticles to the lithium phosphate-containing material is (50-200):1.
  • the seventh aspect of this disclosure provides a lithium-ion battery, including the lithium-ion battery positive electrode described in the sixth aspect of this disclosure.
  • the eighth aspect of this disclosure provides an electrical device including a lithium-ion battery according to the seventh aspect of this disclosure.
  • the lithium phosphate material disclosed herein includes lithium phosphate nanoparticles and lithium phosphate micron-sized particles with pores on their surface.
  • the nanoparticles are embedded in the pores of the micron-sized particles to form an embedded lithium phosphate material.
  • the pores on the surface of the lithium phosphate material increase the porosity of the material, form more reactive sites, and provide more lithium-ion transport channels.
  • the micron-sized particles of the lithium phosphate material disclosed herein have embedded nanoparticles within their pores, resulting in lower water absorption and surface energy.
  • the lithium-ion battery cathode disclosed herein contains the aforementioned lithium phosphate material, which has a balanced number of active sites, specific surface area, and water absorption.
  • the micron-sized particles can increase the porosity of the cathode material, providing lithium-ion transport channels for the electrolyte and improving the rate performance of the lithium-ion battery without gelation.
  • the mutual gradation of micron-sized and nano-sized particles can increase the compaction density of the cathode material layer, thereby improving the reversible capacity of the lithium-ion battery.
  • the first aspect of this disclosure provides a lithium phosphate material, the lithium phosphate material comprising lithium phosphate micron-sized particles with pores on the surface, wherein lithium phosphate nanon-sized particles are embedded in the pores of the lithium phosphate micron-sized particles.
  • the lithium phosphate material disclosed herein comprises lithium phosphate nanoparticles and lithium phosphate micron-sized particles with porous surfaces.
  • the nanoparticles are embedded within the pores of the porous micron-sized particles, forming an embedded lithium phosphate material.
  • the porous surface of this lithium phosphate material increases its porosity, creating more reactive sites and providing more lithium-ion transport channels.
  • the micron-sized particles embedded within the pores of the lithium phosphate material disclosed herein have lower water absorption and surface energy, preventing particle agglomeration during cathode slurry preparation, avoiding lithiation reactions with water, facilitating binder dispersion, inhibiting cross-linking and gelation during slurry preparation, and improving the uniformity of component distribution in the cathode material layer.
  • the D50 particle size of the lithium phosphate nanoparticles is 0.5–0.9 ⁇ m, preferably 0.6–0.8 ⁇ m. This embodiment facilitates the gradation of the two particle sizes, providing more reactive sites for the cathode material.
  • the D50 particle size of the lithium phosphate micron-sized particles is 2.5–10 ⁇ m, preferably 4–8 ⁇ m; the D50 pore size of the channels of the lithium phosphate micron-sized particles is 0.4–0.9 ⁇ m, preferably 0.6–0.8 ⁇ m.
  • the surface of the lithium phosphate micron-sized particles includes one or more channels, preferably a porous structure.
  • the D50 pore size refers to the D50 diameter of the surface openings. The above embodiment is beneficial for providing lithium-ion transport channels for the electrolyte, increasing the porosity of the lithium phosphate material, and improving the rate performance of the battery.
  • the ratio of the D50 particle size of the lithium phosphate micron-sized particles to the D50 particle size of the lithium phosphate nanoparticles is 5 to 10. This embodiment facilitates the rational stacking of micron-sized and nano-sized particles, promotes particle size distribution, balances the pressure compaction and wettability of the electrode sheet, and can meet the requirements of reversible capacity and rate performance when used in batteries.
  • the ratio of the D50 pore size of the micron-sized lithium phosphate particles to the D50 particle size of the nano-sized lithium phosphate particles is 0.8 to 1. This embodiment is beneficial for improving the porosity of the lithium phosphate material and the positive electrode sheet, providing lithium-ion transport channels for the electrolyte, and further improving the reversible capacity and rate performance of the battery.
  • lithium phosphate nanoparticles embedded in the pores of lithium phosphate micron-sized particles in lithium phosphate materials there is no particular limitation on the proportion of lithium phosphate nanoparticles embedded in the pores of lithium phosphate micron-sized particles in lithium phosphate materials.
  • the porosity of the lithium phosphate material is 10-15%, preferably 12-14%. This embodiment is beneficial for increasing the porosity of the positive electrode sheet, providing lithium-ion transport channels for the electrolyte, and further improving the reversible capacity and rate performance of the battery.
  • the porosity of the lithium phosphate material refers to the porosity of a single lithium phosphate material particle. In practical applications, the porosity of the lithium phosphate material can have a certain margin of error.
  • the mass percentage of a single lithium phosphate particle with a porosity of 10-15% can be 95% or more; in further embodiments, the mass percentage can be 96% or more, 97% or more, or 98% or more.
  • the mass ratio of lithium phosphate micron-sized particles to lithium phosphate nano-sized particles can vary within a wide range. This disclosure does not specifically limit the mass ratio of the two; for example, the mass ratio of lithium phosphate micron-sized particles to lithium phosphate nano-sized particles can be 1:(50-200), preferably 1:(50-150).
  • the specific surface area of the lithium phosphate material is 14-20 m2 /g, preferably 14-16 m2 /g. The above embodiments are beneficial for obtaining lithium phosphate materials with small specific surface areas, thereby reducing the water absorption of the cathode raw material.
  • the probability of particle agglomeration can be reduced, which is conducive to the uniform dispersion of binders and conductive agents, making the components uniformly distributed and inhibiting cross-linking that leads to gelation.
  • the above-described embodiments provide more reactive sites and improve the compaction density and porosity of the cathode material layer, resulting in higher reversible capacity and better rate performance of the lithium-ion battery.
  • the lithium phosphate micron-sized particles have a composition represented by the chemical formula LiAxB1 -xPO4 , wherein A is one or more of Ti, V, Mn, Fe, Co, and Ni, B is one or more of Ti, V, Mn, Fe, Co, and Ni, and x is any value between 0 and 1;
  • the lithium phosphate nanon-sized particles have a composition represented by the chemical formula LiA′yB′1 -yPO4 , wherein A′ is one or more of Ti, V, Mn, Fe, Co, and Ni, B′ is one or more of Ti, V, Mn, Fe, Co, and Ni, and y is any value between 0 and 1.
  • A is Mn
  • B is Fe
  • the lithium phosphate micron-sized particles have the chemical formula LiMn x Fe 1-x PO 4 , where x is any value from 0 to 1
  • A′ is Mn
  • B′ is Fe
  • the lithium phosphate nanon-sized particles have the chemical formula LiMn y Fe 1-y PO 4 , where y is any value from 0 to 1.
  • a second aspect of this disclosure provides a method for preparing a lithium phosphate material, the method comprising the following steps:
  • the second lithium source, the second metal source, and the second phosphorus source are mixed, and the resulting mixture is subjected to a second pre-sintering to obtain a second pre-sintered product; the second pre-sintered product and the second carbon source are subjected to a second secondary sintering, and the second secondary sintered product is subjected to a second crushing treatment or a second granulation treatment to obtain lithium phosphate nanoparticles.
  • the preparation method disclosed herein can provide more reactive sites, increase the porosity of the cathode material, and provide lithium ion transport channels for the electrolyte; at the same time, by appropriately grading nano-sized and micro-sized particles, the compaction density of the cathode material layer is increased, further improving the reversible capacity of the lithium-ion battery and enhancing the rate performance of the battery.
  • the composition of lithium phosphate micron-sized particles and lithium phosphate nano-sized particles may be the same or different.
  • the steps of preparing the first pre-sintered product and preparing the second pre-sintered product can be combined. For example, a portion of the obtained first pre-sintered product can be used for a first and second sintering to prepare micron-sized particles, and another portion of the first pre-sintered product can be used for a second and second sintering to prepare nano-sized particles.
  • the first lithium source and the second lithium source are each independently a lithium-containing compound.
  • the lithium-containing compound may be selected from one or more of lithium carbonate, lithium bicarbonate, lithium dihydrogen phosphate, lithium hydroxide, and lithium oxalate.
  • the first metal source and the second metal source are each independently a compound containing one or more elements selected from Ti, V, Mn, Fe, Co, and Ni;
  • the Ti-containing compound may be selected from one or more of titanium dioxide, titanium tetrachloride, titanium nitrate, tetraalkoxy titanium, and acyl titanium;
  • the V-containing compound may be selected from one or more of vanadium pentoxide, ammonium metavanadate, and vanadium oxalate;
  • the Mn-containing compound may be selected from one or more of manganese carbonate, manganese sulfate, manganese phosphate, manganese nitrate, and manganese oxide;
  • the Fe-containing compound may be selected from one or more of ferrous oxide, iron oxide, ferric oxalate, and ferrous acetate;
  • the Co-containing compound may be selected from one or more of cobalt oxide, cobalt carbonate, cobalt chloride, and cobalt acetate
  • the first phosphorus source and the second phosphorus source may each be independently selected from one or more of phosphoric acid, ammonium dihydrogen phosphate, ammonium monohydrogen phosphate and lithium dihydrogen phosphate.
  • the first carbon source and the second carbon source may each be independently selected from organic carbon sources and/or inorganic carbon sources, and may be further selected from one or more of sucrose, glucose, citric acid, phenolic resin, starch and carbon black.
  • the pore-forming agent is a substance that easily decomposes into a gas, which can create a porous structure in the material.
  • the pore-forming agent can be selected from one or more of ethanol, oxalic acid, ammonium bicarbonate, ammonium carbonate, urea, and ammonium chloride.
  • the above embodiment is beneficial for creating porous structures in micron-sized particles, providing channels for lithium-ion transport, resulting in high reversible capacity and better rate performance of the lithium-ion battery.
  • the mass of the pore-forming agent accounts for 1-5% of the total mass of the first pre-sintered product and the pore-forming agent, preferably 3%-5%.
  • the above embodiments are beneficial for forming lithium phosphate micron-sized particles with more suitable size and number of pores, providing lithium-ion transport channels for the electrolyte, resulting in high reversible capacity and better rate performance of the lithium-ion battery; on the other hand, they facilitate the embedding of nano-sized particles, reducing the specific surface area of the material, thereby reducing the water absorption of the raw materials.
  • the agglomeration of nanoparticles can be reduced, which is beneficial for the uniform distribution of binders and conductive agents and inhibits their cross-linking leading to gelation.
  • the amounts of the first/second lithium source, the first/second metal source, and the first/second phosphorus source are not specifically limited.
  • Those skilled in the art can add materials according to the stoichiometric ratio of each element in the chemical formula of the prepared lithium phosphate material.
  • This disclosure does not specifically limit the order in which lithium phosphate micron-sized particles and lithium phosphate nano-sized particles are prepared in step (1).
  • those skilled in the art can prepare lithium phosphate micron-sized particles first, or they can prepare lithium phosphate nano-sized particles first.
  • the conditions for the first and second sintering include: being carried out under a protective gas, wherein the protective gas includes one or more of nitrogen, argon, helium, and hydrogen; the sintering temperature is 710–900°C, preferably 750–850°C; and the sintering time is 6–12 hours, preferably 8–10 hours.
  • the protective gas includes one or more of nitrogen, argon, helium, and hydrogen
  • the sintering temperature is 710–900°C, preferably 750–850°C
  • the sintering time is 6–12 hours, preferably 8–10 hours.
  • a first crushing process is used to form lithium phosphate-containing micron-sized particles from the first secondary sintering product.
  • the conditions for the first crushing process can be conventional conditions in the art that enable the sintered product to become micron-sized particles.
  • the conditions for the first crushing process include: crushing the first secondary sintering product using a ball mill at a speed of 400–500 r/min, preferably 420–480 r/min, for a milling time of 8–10 h, preferably 8.5–9.5 h.
  • the first secondary sintering product is formed into micron-sized particles through a first granulation treatment.
  • the conditions for the first granulation treatment can be conventional conditions in the art that enable the sintered product to become micron-sized particles.
  • the conditions for the first granulation treatment include: a feed gas pressure of 0.8–1.2 MPa, preferably 0.9–1.1 MPa; an inert protective gas flow rate of 30–50 L/min, preferably 40–45 L/min; a gas preheating temperature of 100–150°C, preferably 120–140°C; and a feed solid content of 45–55%, preferably 48–52%.
  • the first granulation treatment includes mixing the first secondary sintering product with a solvent to obtain a slurry with a solid content of 45–55%, and performing a first granulation treatment on the slurry;
  • the solvent used can be water or anhydrous ethanol.
  • the conditions for the second pre-sintering include: being carried out under a protective gas, wherein the protective gas includes one or more of nitrogen, argon, helium, and hydrogen; the pre-sintering temperature is 500–650°C, preferably 550–600°C, and the pre-sintering time is 2–6 hours, preferably 2–4 hours.
  • the protective gas includes one or more of nitrogen, argon, helium, and hydrogen
  • the pre-sintering temperature is 500–650°C, preferably 550–600°C
  • the pre-sintering time is 2–6 hours, preferably 2–4 hours.
  • the second secondary sintering product is formed into lithium phosphate nanoparticles through a second crushing treatment.
  • the conditions for the first crushing treatment can be conventional conditions in the art that enable the sintered product to become nanoparticles.
  • the conditions for the second crushing treatment include: crushing the second secondary sintering product using a ball mill at a speed of 450–600 r/min for a milling time of 10–15 h. The above embodiments facilitate the formation of lithium phosphate nanoparticles of suitable size, providing reactive sites and further improving the rate performance of the battery.
  • the second secondary sintering product is formed into nanoscale particles through a second granulation treatment.
  • the conditions for the second granulation treatment can be conventional conditions in the art that enable the sintered product to become nanoscale particles.
  • the conditions for the second granulation treatment include: a feed gas pressure of 1-1.5 MPa, preferably 1.2-1.4 MPa; an inert protective gas flow rate of 40-60 L/min, preferably 45-55 L/min; a gas preheating temperature of 100-150°C, preferably 120-140°C; and a feed solid content of 45-55%, preferably 48-52%.
  • the mixing is a solid-phase mixing, and is carried out under stirring conditions.
  • the stirring rate is 500–1200 rpm
  • the mixing temperature is 25–35°C
  • the mixing time is 30–60 min.
  • This disclosure does not impose specific limitations on the mixing equipment, and it can be a conventional commercially available product.
  • the above embodiment is beneficial for increasing the compaction density of the positive electrode material layer while providing more reactive sites, and at the same time providing a suitable number of channels to provide transport channels for lithium ions, thereby further improving the rate performance of the battery.
  • the D50 particle size of the lithium phosphate nanoparticles is 0.5–0.9 ⁇ m, preferably 0.6–0.8 ⁇ m; the D50 particle size of the lithium phosphate micron-sized particles is 2.5–10 ⁇ m, preferably 4–8 ⁇ m; and the D50 particle size of the lithium phosphate micron-sized particles is 5–10 times, preferably 6–8 times, the D50 particle size of the lithium phosphate nanoparticles.
  • This embodiment is advantageous in providing more reactive sites and a suitable number of channels to provide transport channels for lithium ions, further improving the rate performance of the battery.
  • This disclosure provides a fourth aspect of a method for preparing a positive electrode for a lithium-ion battery, the method comprising: mixing a lithium phosphate material, a conductive agent, a binder, and a solvent to form a positive electrode slurry; forming a positive electrode slurry layer on a positive electrode current collector; removing the solvent from the positive electrode slurry layer to form a positive electrode sheet comprising a positive electrode material layer; wherein the lithium phosphate material is the lithium phosphate material described in the first aspect and/or the third aspect of this disclosure.
  • This disclosure uses lithium phosphate materials to prepare the cathode, wherein the nano-sized and micro-sized particles can provide more reactive sites, and the micro-sized particles have channels, which can improve the porosity of the cathode material and provide lithium ion transport channels for the electrolyte.
  • the appropriate gradation of the two can improve the compaction density of the cathode material layer, resulting in high reversible capacity and better rate performance of the lithium-ion battery.
  • the conductive agent can be one or more of carbon black, carbon nanotubes, acetylene black, and graphene
  • the binder can be one or more of polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), and polytetrafluoroethylene (PTFE)
  • the solvent can be one or more of N-methylpyrrolidone, N-methylformamide, ethanol, and acetone.
  • the positive electrode slurry further includes a dispersant, which may be one or more of polyvinylpyrrolidone (PVP), polyacrylic acid (PAA), polyethyleneimine (PEI), and acrylic acid-maleic acid copolymer (PAMA); the mass ratio of the lithium phosphate material to the dispersant may vary in a wide range, for example, it may be 1:(0.01 to 0.03), preferably 1:(0.015 to 0.025).
  • a dispersant which may be one or more of polyvinylpyrrolidone (PVP), polyacrylic acid (PAA), polyethyleneimine (PEI), and acrylic acid-maleic acid copolymer (PAMA);
  • PVP polyvinylpyrrolidone
  • PAA polyacrylic acid
  • PEI polyethyleneimine
  • PAMA acrylic acid-maleic acid copolymer
  • the mass ratio of the lithium phosphate material to the dispersant may vary in a wide range, for example, it may be 1:(0.01 to
  • the above embodiments facilitate the stress-induced splitting of weak points in the lithium phosphate material particles, i.e., the embedded boundaries, allowing the positive electrode material encapsulating a quantitative amount of auxiliary materials to further separate into nano-sized and micro-sized particles. This ensures stable dispersion of the slurry and guarantees a large number of reactive sites in the positive electrode sheet. Furthermore, the combination of nano-sized particles with porous micro-sized large particles increases the compaction density of the positive electrode sheet, exposing the pore structure to provide lithium-ion transport channels for the electrolyte, further improving the reversible capacity and rate performance of the battery.
  • the mass ratio of the lithium phosphate micron-sized particles to the lithium phosphate nanon-sized particles can vary within a wide range, for example, it can be 1:(50-200), preferably 1:(100-150).
  • This embodiment is advantageous for obtaining a cathode material layer with suitable gradation, for providing more reactive sites while simultaneously providing lithium-ion transport channels, for increasing the porosity of the cathode material, for increasing the compaction density of the cathode material layer, and for further improving the reversible capacity and rate performance of the battery.
  • the positive electrode slurry further comprises positive electrode material nanoparticles. More specifically, the mass ratio of the positive electrode material nanoparticles to the lithium phosphate-containing material is (50-200):1, preferably (100-150):1.
  • This embodiment is advantageous for obtaining a positive electrode material layer with suitable gradation, for providing more reactive sites while simultaneously providing lithium-ion transport channels, for increasing the porosity of the positive electrode material, for increasing the compaction density of the positive electrode material layer, and for further improving the reversible capacity and rate performance of the battery.
  • cathode material nanoparticles can be added during the preparation of the lithium phosphate-containing material.
  • cathode material nanoparticles can be added during the mixing step of nano-sized and micro-sized particles.
  • nano-sized and micro-sized particles can be prepared directly at a mass ratio of (50-200):1 of the cathode material nanoparticles to the lithium phosphate-containing material.
  • implementations are beneficial in reducing the probability of nanoparticle agglomeration during the mixing and slurry preparation process, promoting uniform dispersion of binders and conductive agents, ensuring a uniform distribution of all components, and inhibiting cross-linking leading to gelation. They also facilitate appropriate gradation between the cathode material nanoparticles and the lithium phosphate-containing material, providing more reactive sites while increasing the compaction density of the cathode material layer, further improving the reversible capacity and rate performance of the battery.
  • the fifth aspect of this disclosure provides a lithium-ion battery cathode prepared by the method described in the fourth aspect of this disclosure.
  • This sixth aspect of the disclosure provides a positive electrode for a lithium-ion battery, the positive electrode comprising a positive electrode current collector and a positive electrode material layer disposed on at least one side of the positive electrode current collector, the positive electrode material layer containing a lithium phosphate material; wherein the lithium phosphate material is the lithium phosphate material described in the first aspect and/or the third aspect of the disclosure.
  • the positive electrode material layer of this disclosure has micron-sized and nano-sized particles with porous surfaces distributed within it, ensuring a large number of reactive sites while simultaneously increasing the compaction density and porosity of the positive electrode sheet through the combination of nano-sized particles and porous micron-sized particles, further enhancing the reversible capacity and rate performance of the battery.
  • the positive electrode includes a positive electrode current collector and a positive electrode material layer disposed on both sides of the positive electrode current collector.
  • the positive electrode material layer further contains positive electrode material nanoparticles; the mass ratio of the positive electrode material nanoparticles to the lithium phosphate-containing material can vary within a wide range, for example, it can be (50-200):1, preferably (100-150):1.
  • the composition of the positive electrode material nanoparticles can be the same as or different from that of the lithium phosphate-containing material nanoparticles.
  • the positive electrode material nanoparticles have a composition represented by the chemical formula LiA′′ z B′′ 1-z PO 4 , wherein A′′ is one or more of Ti, V, Mn, Fe, Co, and Ni, B′′ is one or more of Ti, V, Mn, Fe, Co, and Ni, and z is any value between 0 and 1.
  • A′′ is one or more of Ti, V, Mn, Fe, Co, and Ni
  • B′′ is one or more of Ti, V, Mn, Fe, Co, and Ni
  • z is any value between 0 and 1.
  • the porosity of the positive electrode material layer is 15-25%, preferably 17-20%.
  • the above embodiments are beneficial for increasing the porosity of the positive electrode material layer, providing lithium-ion transport channels for the electrolyte, and improving the rate performance of the lithium-ion battery.
  • the seventh aspect of this disclosure provides a lithium-ion battery, including the lithium-ion battery positive electrode described in the fifth aspect and/or the sixth aspect of this disclosure.
  • the electrical device may include, but is not limited to, mobile communication devices, automobiles, and electrical appliances.
  • the specific surface area of the composite particles was measured using the BET method on a TriStarII3020 gas adsorption analyzer; the porosity of the composite particles, the porosity of the lithium phosphate-containing material, the porosity of the cathode material layer, and the D50 pore size of the micron-sized particles were measured using a ZEISS Crossbeam 550 focused ion beam scanning electron microscope; the D50 particle size of the micron-sized particles and the D50 particle size of the nano-sized particles were measured using a PSA200702 laser particle size analyzer.
  • the viscosity of the cathode slurry was measured using a ViscoQC 300(L) rotational rheometer.
  • lithium carbonate, iron oxide, manganese carbonate and ammonium dihydrogen phosphate with a molar ratio of 0.5:0.8:0.1:1 are ball-milled and stirred until they are evenly mixed.
  • the above-mixed raw materials are added to a high-temperature sintering furnace, argon gas is introduced, the pre-sintering temperature is maintained at 600°C, and sintering is continued for 2 hours to obtain the first pre-sintered product.
  • the first pre-sintered product after being allowed to stand and cool, was poured into a ball mill and glucose was added. The mixture was then ball-milled until it was evenly dispersed. Then, 3% by weight of ammonium bicarbonate was added to the first pre-sintered product and ammonium bicarbonate and mixed. The powder containing the pore-forming agent was then placed back into the sintering furnace for the first and second sintering at 750°C for 8 hours. The products after the first and second sintering were then mixed with anhydrous ethanol to obtain a slurry with a solid content of 50%.
  • the slurry was then spray-granulated with a feed pressure of 1 MPa, an argon flow rate of 40 L/min, and an argon preheating temperature of 120°C to obtain porous micron-sized LMFP particles with a D50 particle size of 4 ⁇ m and a D50 pore size of 0.6 ⁇ m.
  • the product after the second sintering was then mixed with anhydrous ethanol to obtain a slurry with a solid content of 50%.
  • the slurry was then spray-granulated with a feed pressure of 1.2 MPa and an argon gas flow rate of 50 L/min to obtain nano-sized LMFP particles.
  • the argon gas preheating temperature was 120°C, and the D50 particle size of the nano-sized LMFP particles was 0.65 ⁇ m.
  • the porous micron-sized particles and nano-sized particles obtained above are stirred and mixed at a mass ratio of 1:100. Through mixing, most of the nano-sized particles enter the pores of the micron-sized particles to form composite particles.
  • the mixing temperature is 25°C
  • the mixing time is 40min
  • the stirring speed is 800rpm.
  • the above composite particles are mixed with conductive agent CNT, binder PVDF, dispersant PVP and solvent NMP in a mass ratio of 1:0.02:0.04:0.02:0.7 to form a positive electrode slurry with a solid content of 50% by weight.
  • the positive electrode slurry is then sheared at a shear rate of 6000 rpm at 25°C. After stirring for 20 minutes, the sheared slurry is coated onto the current collector, forming a positive electrode slurry layer on the current collector. During shearing, some nano-sized particles detach from the channels of micron-sized particles.
  • the resulting sheared positive electrode slurry contains lithium phosphate material with an embedded structure and dispersed positive electrode material nanoparticles.
  • the solvent in the positive electrode slurry layer is removed to form a positive electrode sheet containing a positive electrode material layer.
  • the positive electrode sheet is then assembled with a separator, graphite anode, etc., into a full cell for testing.
  • step (1) Similar to Example 1, except that the conditions for preparing porous micron-sized particles in step (1) are different, as follows:
  • the first pre-sintered product after being allowed to cool, was poured into a ball mill, and glucose was added for ball milling until the particles were evenly dispersed. Then, 3% by weight of ammonium bicarbonate was added to the first pre-sintered product and mixed with the ammonium bicarbonate. The powder containing the pore-forming agent was then placed back into a sintering furnace for the first and second sintering at 850°C for 6 hours. The products after the first and second sintering were mixed with anhydrous ethanol to obtain a slurry with a solid content of 50%.
  • the slurry was then subjected to spray granulation treatment with a feed pressure of 1 MPa, an argon flow rate of 40 L/min, and an argon preheating temperature of 120°C to obtain porous micron-sized LMFP particles.
  • the D50 particle size of the micron-sized particles was 4 ⁇ m, and the D50 pore size was 0.5 ⁇ m.
  • step (1) Similar to Example 1, except that the conditions for preparing porous micron-sized particles in step (1) are different, as follows:
  • the first pre-sintered product after being allowed to cool, was poured into a ball mill, and glucose was added for ball milling until the particles were evenly dispersed. Then, 3% by weight of ammonium bicarbonate was added to the first pre-sintered product and mixed with the ammonium bicarbonate. The powder containing the pore-forming agent was then placed back into a sintering furnace for the first and second sintering at 750°C for 8 hours. The products after the first and second sintering were then mixed with anhydrous ethanol to obtain a slurry with a solid content of 50%.
  • the slurry was then subjected to spray granulation treatment with a feed pressure of 1.3 MPa, an argon flow rate of 52 L/min, and an argon preheating temperature of 120°C to obtain porous micron-sized LMFP particles.
  • the micron-sized particles had a D50 particle size of 3 ⁇ m and a D50 pore size of 0.6 ⁇ m.
  • step (2) the mass ratio of the porous micron-sized particles and nano-sized particles is 1:50.
  • step (3) Similar to Example 1, except that in step (3), the shear rate is 4800 rpm.
  • step (1) Similar to Example 1, except that in step (1), the feed pressure is 1 MPa, the argon flow rate is 40 L/min, the argon preheating temperature is 120 °C, and the D50 particle size of the nano-sized LMFP particles is 0.9 ⁇ m.
  • step (1) when preparing micron-sized particles: the first and second sintering temperatures are 900°C, and the sintering time is 12 hours; the feed pressure is 0.8MPa, the argon flow rate is 30L/min, and the argon preheating temperature is 120°C, resulting in micron-sized LMFP particles with a D50 particle size of 10 ⁇ m and a D50 pore size of 0.6 ⁇ m.
  • step (1) when preparing nanoscale particles: the temperature of the second sintering is 600°C, and the sintering time is 4h; the feed pressure is 1.5MPa, the argon flow rate is 60L/min, and the argon preheating temperature is 120°C, so that the D50 particle size of the nanoscale LMFP particles is 0.5 ⁇ m.
  • Lithium carbonate, iron oxide, manganese carbonate, and ammonium dihydrogen phosphate were ball-milled and stirred in a molar ratio of 0.5:0.8:0.1:1 until homogeneous.
  • the mixed raw materials were then added to a high-temperature sintering furnace, and argon gas was introduced.
  • the pre-sintering temperature was maintained at 600°C for 2 hours to obtain a pre-sintered product.
  • the pre-sintered product was then poured into a ball mill after static cooling, and glucose was added for ball milling until uniform dispersion. The powder was then placed back into the sintering furnace for secondary sintering at 650°C for 6 hours.
  • Nanoscale LMFP particles are mixed with conductive agent CNT, binder PVDF, dispersant PVP and solvent NMP in a mass ratio of 1:0.02:0.04:0.02:0.7 to form a slurry.
  • the slurry is coated on the current collector and assembled with a separator, graphite anode and other components to form a full cell for testing.
  • step (1) ammonium bicarbonate, a pore-forming agent, is not added in step (1), as follows:
  • Lithium carbonate, iron oxide, manganese carbonate and ammonium dihydrogen phosphate with a molar ratio of 0.5:0.8:0.1:1 were ball-milled and stirred until uniformly mixed.
  • the mixed raw materials were added to a high-temperature sintering furnace, argon gas was introduced, the pre-sintering temperature was maintained at 600°C, and sintering was continued for 2 hours to obtain the first pre-sintered product.
  • the first pre-sintered product was poured into a ball mill after being cooled and statically placed, and glucose was added and ball-milled until uniformly dispersed. The powder was then put back into the sintering furnace for secondary sintering at a temperature of 750°C for 8 hours.
  • the product after secondary sintering was then mixed with anhydrous ethanol to obtain a slurry with a solid content of 50%.
  • the slurry was spray-granulated with a feed pressure of 1MPa, an argon flow rate of 40L/min, and an argon preheating temperature of 120°C to obtain non-porous micron-sized LMFP particles with a D50 particle size of 4 ⁇ m.
  • Lithium carbonate, iron oxide, manganese carbonate, and ammonium dihydrogen phosphate in a stoichiometric ratio of 0.5:0.8:0.1:1 were ball-milled and stirred until uniformly mixed.
  • the mixed raw materials were then added to a high-temperature sintering furnace, argon gas was introduced, and the pre-sintering temperature was maintained at 600°C for 2 hours to obtain a second pre-sintered product.
  • the second pre-sintered product was then poured into a ball mill after being allowed to cool, and glucose was added and ball-milled until uniformly dispersed.
  • the powder mixed with glucose was then placed back into the sintering furnace for a second sintering at 650°C for 6 hours.
  • the product after the second sintering was then mixed with anhydrous ethanol to obtain a slurry with a solid content of 50%.
  • the slurry was then spray-granulated under the following conditions: feed pressure of 1.2 MPa, argon gas flow rate of 50 L/min, and argon gas preheating temperature of 120°C to obtain nano-sized LMFP particles with a D50 particle size of 0.65 ⁇ m.
  • the above-obtained non-porous micron-sized particles and nano-sized particles are stirred and mixed at a mass ratio of 1:100 to obtain mixed particles containing non-porous micron-sized particles and nano-sized particles.
  • the mixing temperature is 25°C and the stirring speed is 800rpm.
  • the above composite particles are mixed with conductive agent CNT, binder PVDF, dispersant PVP and solvent NMP in a mass ratio of 1:0.02:0.04:0.02:0.7 to form a positive electrode slurry; then the positive electrode slurry is sheared at a shearing rate of 6000 rpm, the solid content of the positive electrode slurry is 50% by weight, sheared at 25°C, stirred for 20 minutes, and then the sheared slurry is coated on the current collector, the slurry forms a positive electrode slurry layer on the current collector, the solvent in the positive electrode slurry layer is removed, a positive electrode sheet containing a positive electrode material layer is formed, and it is assembled with a separator, graphite negative electrode, etc. to form a full cell for testing.
  • the D50 particle size, D50 pore size, D50 particle size of the micron-sized particles, the specific surface area and porosity of the composite particles, the specific surface area of the lithium phosphate-containing material, and the porosity of the cathode material layer obtained in Examples 1-9 and Comparative Examples 1-2 were tested; the test results are shown in Table 1.
  • the characterization of lithium phosphate materials in this disclosure involves testing the particles after the sheared slurry has undergone processes such as filtration, drying, and sieving.
  • the specific surface area of the composite particles in Examples 1 to 9 in Table 1 refers to the specific surface area of the composite particles obtained by mixing in step (2).
  • the porosity of composite particles refers to the percentage of the volume of pores within a single composite particle relative to the total volume.
  • Table 1 shows the porosity of composite particles in Examples 1-9, which were tested in step (2) by mixing.
  • the specific surface area of the mixed particles containing non-porous micron-sized particles and nano-sized particles obtained in step (2) of Comparative Example 2 is 18.6 m2 /g. According to the data in Table 1, compared with Comparative Example 2, the specific surface area of the composite particles obtained by mixing in step (2) of Example 1 is smaller, indicating that during the mixing process, the nano-sized particles are embedded in the pores of the micron-sized particles. According to the comparison between the porosity of the composite particles and the porosity of the lithium phosphate material in Example 1, after the shearing treatment in step (3), the porosity of the lithium phosphate material after shearing is higher than that of the composite particles, indicating that shearing causes some nano-sized particles to fall out from the pores of the micron-sized particles.
  • the specific surface area of the nano-sized particles in Comparative Example 1 is 21 m2 /g.
  • the lithium phosphate material prepared by the method of this disclosure has a smaller specific surface area.
  • it can reduce the water absorption of the positive electrode raw materials.
  • it can reduce the probability of particle agglomeration, which is conducive to the uniform dispersion of binders and conductive agents, inhibits their cross-linking leading to gelation, and ensures stable dispersion of the slurry.
  • the compaction density of the positive electrode material is improved, and the pore structure of the micron-sized particles is exposed to provide lithium-ion transport channels for the electrolyte, further improving the reversible capacity of the battery and enhancing the rate performance of the battery.
  • Examples 1-7 show that the positive electrode slurry of this disclosure exhibits less particle agglomeration and does not form gel within 4 hours. Comparative Example 1, however, shows severe gelation within 1 hour, resulting in continuous particle agglomeration and significantly affecting the ion transport rate of the battery. Comparative Example 2, without the addition of a pore-forming agent, has a larger overall particle surface area compared to Example 1, further increasing water absorption and the cross-linking reaction area with the binder. The resulting slurry forms gel within 2 hours, and the micron-sized particles lack pore structure, leading to a longer solid-phase lithium-ion transport distance and poor rate performance.
  • Example 2 shows that the pore-forming agent content in Example 1 is within the preferred range of this disclosure, enabling micron-sized particles to better form a porous structure, which is more conducive to the embedding of nano-sized particles, reducing the probability of water absorption and preventing gelation of the slurry.
  • Example 3 shows that the ratio of the D50 pore size of the micron-sized particles to the D50 particle size of the nano-sized particles in Example 1 is within the preferred range of this disclosure, which is more conducive to the embedding of nano-sized particles into the pores of the micron-sized particles, avoiding agglomeration and improving the rate performance of the battery.
  • Example 4 shows that the ratio of the D50 particle size of the micron-sized particles to the D50 particle size of the nano-sized particles in Example 1 is within the preferred range of this disclosure, preventing gelation of the slurry within 4 hours and further improving the rate performance of the battery.
  • Example 5 shows that the gradation of porous micron-sized particles and nano-sized particles in Example 1 is better than that in Example 5, which is more conducive to increasing active sites and further improving the rate performance of the battery.
  • Example 6 shows that the shear rate in Example 1 is within the preferred range of this disclosure, which is beneficial for better separation of nanoscale particles from microscale particles and improves the rate performance of the battery.
  • Example 7 shows that the ratio of the D50 particle size of microscale particles to the D50 particle size of nanoscale particles, and the ratio of the D50 pore size of microscale particles to the D50 particle size of nanoscale particles, are within the preferred range of this disclosure. This is more conducive to the embedding of nanoscale particles into the pores of microscale particles, avoiding agglomeration and improving the rate performance of the battery.
  • Example 8 shows that the ratio of the D50 particle size of microscale particles to the D50 particle size of nanoscale particles is within the preferred range of this disclosure, which is beneficial for increasing the porosity of the positive electrode material layer, facilitating lithium-ion transport, and resulting in better rate performance of the battery.
  • Example 9 shows that the ratio of the D50 pore size of the micron-sized particles to the D50 particle size of the nano-sized particles in Example 1 is within the preferred range of this disclosure, which avoids agglomeration and prevents the slurry from gelling within 4 hours, thus improving the rate performance of the battery.

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Abstract

一种含锂磷酸盐材料、锂离子电池正极及制备方法与应用，该含锂磷酸盐材料包括表面具有孔道的含锂磷酸盐微米级颗粒，该含锂磷酸盐微米级颗粒的孔道内嵌有含锂磷酸盐纳米级颗粒。

Description

一种含锂磷酸盐材料、锂离子电池正极及制备方法与应用
相关申请的交叉引用
本公开要求在2024年6月19日提交中国专利局、申请号为202410793743.2、名称为“一种含锂磷酸盐材料、锂离子电池正极及制备方法与应用”的中国专利申请的优先权，其全部内容通过引用结合在本公开中。
技术领域
本公开涉及锂离子电池技术领域，具体地，涉及一种含锂磷酸盐材料、锂离子电池正极及制备方法与应用。
背景技术
磷酸铁锂(LiFePO4)作为锂电池的正极材料具有结构稳定性好、安全性高、循环性能好等优点，已被广泛应用在新能源汽车的动力装置的锂离子电池上。磷酸锰铁锂正极材料(LiMnxFe1-xPO4，0＜x＜1)是采用锰部分取代LiFePO4正极材料中的铁形成的新型材料。这样的掺杂提升了LiFePO4的电压平台，进一步提升了其能量密度，因此取得了重点研究关注。
磷酸锰铁锂材料存在电子/离子传导速率较慢的问题，纳米化改性是提升磷酸锰铁锂材料电子/离子传导速率的重要技术。采用纳米化的磷酸锰铁锂颗粒可使正极材料的比表面积增大，使电解液和正极材料充分接触，增加反应活性位点，极大缩短Li+的传输距离，提升电池的可逆容量及倍率性能。但是纳米化的磷酸锰铁锂颗粒表面能较高，易发生团聚，在极片制备过程中难以在浆料中分散均匀。此外，纳米化的正极材料的比表面积增大会使正极材料极易吸水，水与正极材料中表面亲水性的Li相接触后发生锂化反应，会影响电池的存储容量保持率。并且锂化反应生成的碱性物质会与粘结剂聚偏氟乙烯发生消除反应，生成的双键使粘结剂聚偏氟乙烯分子链之间发生交联反应，形成凝胶，导致正极材料在铝箔上的涂敷性较差或是形成凝胶麻点，阻碍锂离子迁移，造成电流分配不均、析锂等风险。简言之，现有的LiMnxFe1-xPO4材料难以在活性位点数量、材料吸水性与离子传导速率方面达到平衡，从而影响电池可逆容量及倍率性能的进一步提升。
发明内容
本公开的目的是提供一种含锂磷酸盐材料、锂离子电池正极及制备方法与应用，该含锂磷酸盐材料能够提供较多反应活性位点，且材料的比表面积和吸水性适宜，用于锂离子电池时，能够提供足够的锂离子传输通道，在降低凝胶风险的前提下提高电池的可逆容量和倍率性能。
为了实现上述目的，本公开第一方面提供一种含锂磷酸盐材料，所述含锂磷酸盐材料包括表面具有孔道的含锂磷酸盐微米级颗粒，所述含锂磷酸盐微米级颗粒的孔道内嵌有含锂磷酸盐纳米级颗粒。
可选地，所述含锂磷酸盐微米级颗粒的D50粒径与所述含锂磷酸盐纳米级颗粒的D50粒径的比值为5～10。
可选地，所述含锂磷酸盐微米级颗粒的孔道的D50孔径与所述含锂磷酸盐纳米级颗粒的D50粒径的比值为0.8～1。
可选地，所述含锂磷酸盐纳米级颗粒的D50粒径为0.5～0.9μm。
可选地，所述含锂磷酸盐微米级颗粒的D50粒径为2.5～10μm，所述孔道的D50孔径为0.4～0.9μm。
可选地，所述含锂磷酸盐材料的孔隙率为10～15％。
可选地，所述含锂磷酸盐微米级颗粒具有化学式LiAxB1-xPO4表示的组成，其中，A为Ti、V、Mn、Fe、Co和Ni中的一种或多种，B为Ti、V、Mn、Fe、Co和Ni中的一种或多种，x为0～1之间的任意数值；
所述含锂磷酸盐纳米级颗粒具有化学式LiA′yB′1-yPO4表示的组成，其中，A′为Ti、V、Mn、Fe、Co和Ni中的一种或多种，B′为Ti、V、Mn、Fe、Co和Ni中的一种或多种，y为0～1之间的任意数值。
本公开第二方面提供一种含锂磷酸盐材料的制备方法，所述制备方法包括如下步骤：
(1)将第一锂源、第一金属源和第一磷源混合，对所得混合物进行第一预烧结，得到第一预烧结产物；将所述第一预烧结产物、第一碳源和造孔剂进行第一二次烧结，对所述第一二次烧结产物进行第一破碎处理或第一造粒处理，得到含锂磷酸盐微米级颗粒；
将第二锂源、第二金属源和第二磷源混合，对所得混合物进行第二预烧结，得到第二预烧结产物；将所述第二预烧结产物和第二碳源进行第二二次烧结，对所述第二二次烧结产物进行第二破碎处理或第二造粒处理，得到含锂磷酸盐纳米级颗粒；
(2)将所述含锂磷酸盐纳米级颗粒和所述含锂磷酸盐微米级颗粒进行混合。
可选地，所述第一金属源和第二金属源各自独立地为含有Ti、V、Mn、Fe、Co和Ni中的一种或多种元素的化合物；所述第一碳源和第二碳源各自独立地选自蔗糖、葡萄糖、柠檬酸、酚醛树脂、淀粉和碳黑中的一种或多种。
可选地，步骤(1)中，所述造孔剂的质量占所述第一预烧结产物和造孔剂总质量的1～5％；所述造孔剂选自乙醇、草酸、碳酸氢铵、碳酸铵、尿素和氯化铵中的一种或多种。
可选地，步骤(1)中，所述第一预烧结的条件包括：在保护气体下进行，预烧结温度为500～650℃，预烧结时间为2～6h；
所述第一二次烧结的条件包括：在保护气体下进行，烧结温度为710～900℃，烧结时间为6～12h；
所述第一破碎处理的条件包括：使用球磨机对所述第一二次烧结产物进行破碎，球磨机转速为400～500r/min，球磨时间为8～10h；
所述第一造粒处理的条件包括：进料气压为0.8～1.2MPa，惰性保护气体流量为30～50L/min，气体预热温度为100～150℃，进料固含量为45～55％。
可选地，步骤(1)中，所述第二预烧结的条件包括：在保护气体下进行，预烧结温度为500～650℃，预烧结时间为2～6h；
所述第二二次烧结的条件包括：在保护气体下进行，烧结温度为600～700℃，烧结时间为4～8h；
所述第二破碎处理的条件包括：使用球磨机对所述第二二次烧结产物进行破碎，球磨机转速为450～600r/min，球磨时间为10～15h；
所述第二造粒处理的条件包括：进料气压为1～1.5MPa，惰性保护气体流量为40～60L/min，气体预热温度为100～150℃，进料固含量为45～55％。
可选地，步骤(2)中，所述混合为固相混合，且在搅拌的条件下进行，所述搅拌的速率为500～1200rpm，所述混合的温度为25～35℃，所述混合的时间为30～60min。
可选地，步骤(2)中，所述含锂磷酸盐纳米级颗粒的D50粒径为0.5～0.9μm；所述含锂磷酸盐微米级颗粒的D50粒径为2.5～10μm；所述含锂磷酸盐微米级颗粒的D50粒径为含锂磷酸盐纳米颗粒的D50粒径的5～10倍。
本公开第三方面提供一种由本公开第二方面所述制备方法制备的含锂磷酸盐材料。
本公开第四方面提供一种制备锂离子电池正极的方法，所述方法包括：使含锂磷酸盐材料、导电剂、粘结剂和溶剂进行混合形成正极浆料；使所述正极浆料在正极集流体上形成正极浆料层，除去所述正极浆料层中的溶剂，形成包含正极材料层的正极极片；
其中，所述含锂磷酸盐材料为本公开第一方面和/或本公开第三方面所述的含锂磷酸盐材料。
可选地，该方法还包括：在形成正极浆料层之前，对所述正极浆料进行剪切处理，所述剪切处理的条件包括：剪切速率为4000～8000rpm，所述剪切处理的温度为20～35℃。
可选地，所述含锂磷酸盐微米级颗粒和含锂磷酸盐纳米级颗粒的质量比为1：(50～200)。
本公开第五方面提供一种由本公开第四方面所述方法制备的锂离子电池正极。
本公开第六方面提供一种锂离子电池正极，所述正极包括集流体和设置在所述正极集流体至少一侧的正极材料层；所述正极材料层含有含锂磷酸盐材料；其中，所述含锂磷酸盐材料为本公开第一方面和/或本公开第三方面所述的含锂磷酸盐材料。
可选地，所述正极材料层的孔隙率为15～25％。
可选地，所述正极材料层还含有正极材料纳米颗粒；
所述正极材料纳米颗粒具有化学式LiA″zB″1-zPO4表示的化学组成，其中，A″为Ti、V、Mn、Fe、Co和Ni中的一种或多种，B″为Ti、V、Mn、Fe、Co和Ni中的一种或多种，z为0～1之间的任意数值；
所述正极材料纳米颗粒与所述含锂磷酸盐材料的质量比为(50～200):1。
本公开第七方面提供一种锂离子电池，包括本公开第六方面所述的锂离子电池正极。
本公开第八方面提供一种用电装置，包括本公开第七方面的锂离子电池。
通过上述技术方案，本公开的含锂磷酸盐材料包括含锂磷酸盐纳米级颗粒和表面具有孔道的含锂磷酸盐微米级颗粒，该纳米级颗粒嵌入微米级颗粒的表面孔道中，形成嵌入式含锂磷酸盐材料；该含锂磷酸盐材料表面具有孔道，提高了材料的孔隙率，形成较多的反应活性位，并能够提供更多的锂离子传输通道。并且相比于采用纳米化颗粒的正极材料，本公开含锂磷酸盐材料的微米级颗粒的孔道内嵌有纳米级颗粒，使得含锂磷酸盐材料的吸水性和表面能更低，能够避免正极浆料制备中的颗粒团聚、避免与水发生锂化反应的现象，并利于粘结剂和导电剂分散，能够抑制制浆过程的交联和凝胶，提高正极材料层中各组分的分布均匀性。
本公开的锂离子电池正极中包含上述的含锂磷酸盐材料，该材料具有均衡的活性位点数量、比表面积和吸水性，且微米级颗粒的孔道能够提高正极材料的孔隙率，为电解液提供锂离子传输通道，在不发生凝胶的同时提高锂离子电池的倍率性能；微米级颗粒和纳米级颗粒的相互级配能够提高正极材料层的压实密度，从而提高锂离子电池的可逆容量。
本公开的其他特征和优点将在随后的具体实施方式部分予以详细说明。
具体实施方式
以下对本公开的具体实施方式进行详细说明。应当理解的是，此处所描述的具体实施方式仅用于说明和解释本公开，并不用于限制本公开。
本公开第一方面提供一种含锂磷酸盐材料，所述含锂磷酸盐材料包括表面具有孔道的含锂磷酸盐微米级颗粒，所述含锂磷酸盐微米级颗粒的孔道内嵌有含锂磷酸盐纳米级颗粒。
本公开的含锂磷酸盐材料包括含锂磷酸盐纳米级颗粒和表面具有孔道的含锂磷酸盐微米级颗粒，该纳米级颗粒嵌入在表面多孔的微米级颗粒的孔道中，形成嵌入式含锂磷酸盐材料。该含锂磷酸盐材料表面具有孔道，提高了材料的孔隙率，形成较多的反应活性位，并能够提供更多的锂离子传输通道。并且相比于采用纳米化颗粒的正极材料，本公开的含锂磷酸盐材料的微米级颗粒的孔道内嵌有纳米级颗粒，使其吸水性和表面能更低，能够避免正极浆料制备中的颗粒团聚、避免与水发生锂化反应的现象，并利于粘结剂分散，能够抑制制浆过程的交联和凝胶，提高正极材料层中各组分的分布均匀性。
根据本公开的一种实施方式，所述含锂磷酸盐纳米级颗粒的D50粒径为0.5～0.9μm，优选为0.6～0.8μm。上述实施方式，有利于两种颗粒级配，为正极材料提供较多的反应活性位点。
根据本公开的一种实施方式，所述含锂磷酸盐微米级颗粒的D50粒径为2.5～10μm，优选为4～8μm；所述含锂磷酸盐微米级颗粒孔道的D50孔径为0.4～0.9μm，优选为0.6～0.8μm。所述含锂磷酸盐微米颗粒的表面包括一个或多个孔道，优选为多孔结构。本公开中，D50孔径是指表面开孔的D50直径。上述实施方式，有利于为电解液提供锂离子传输通道，提高含锂磷酸盐材料的孔隙率，提高电池的倍率性能。
根据本公开的一种实施方式，所述含锂磷酸盐微米级颗粒的D50粒径与所述含锂磷酸盐纳米颗粒的D50粒径的比值为5～10。上述实施方式，有利于微米级颗粒和纳米级颗粒合理堆积，有利于两种颗粒级配，平衡极片的压力压实和浸润性，用于电池时可以满足电池的可逆容量和倍率性能的要求。
根据本公开的一种实施方式，所述含锂磷酸盐微米级颗粒的孔道的D50孔径与所述含锂磷酸盐纳米级颗粒的D50粒径的比值为0.8～1。上述实施方式，有利于提高含锂磷酸盐材料和正极极片的孔隙率，为电解液提供锂离子传输通道，进一步提高电池的可逆容量和倍率性能。
根据本公开，含锂磷酸盐材料中，嵌入在含锂磷酸盐微米级颗粒的孔道内的含锂磷酸盐纳米级颗粒的占比没有特别限定。
根据本公开的一种实施方式，所述含锂磷酸盐材料的孔隙率为10～15％，优选为12～14％。上述实施方式，有利于提高正极极片的孔隙率，为电解液提供锂离子传输通道，进一步提高电池的可逆容量和倍率性能。本公开中，含锂磷酸盐材料的孔隙率是指单颗含锂磷酸盐材料颗粒的孔隙率。在实际应用中，含锂磷酸盐材料的孔隙率可以存在一定的误差，例如一种具体的实施方式中，以含锂磷酸盐材料的总重量为基准，孔隙率为10～15％的单颗含锂磷酸盐颗粒的质量占比可以为95％以上；进一步的实施方式中，质量占比可以为96％以上，97％以上，98％以上。
进一步地，本公开提供的含锂磷酸盐材料中，含锂磷酸盐微米级颗粒与含锂磷酸盐纳米级颗粒的质量比可以在较大范围内变化，本公开对两者的质量比没有特别限定，例如含锂磷酸盐微米级颗粒与含锂磷酸盐纳米级颗粒的质量比可以为1：(50～200)，优选为1：(50～150)。所述含锂磷酸盐材料的比表面积为14～20m2/g，优选为14～16m2/g。上述实施方式，有利于获得比表面积小的含锂磷酸盐材料，从而可以降低正极原料的吸水程度；在混料制浆过程中，由于大部分纳米级颗粒嵌入在微米级颗粒的孔道内，而并未直接存在于浆液中，因此可以减少颗粒团聚的机率，利于粘结剂和导电剂的分散均匀，使各组分均一分布，抑制其交联导致凝胶。上述实施方式，既提供了较多的反应活性位点又提高了正极材料层的压实密度和孔隙率，使锂离子电池的可逆容量高，电池的倍率性能更好。
根据本公开的一种实施方式，所述含锂磷酸盐微米级颗粒具有化学式LiAxB1-xPO4表示的组成，其中，A为Ti、V、Mn、Fe、Co和Ni中的一种或多种，B为Ti、V、Mn、Fe、Co和Ni中的一种或多种，x为0～1之间的任意数值；所述含锂磷酸盐纳米级颗粒具有化学式LiA′yB′1-yPO4表示的组成，其中，A′为Ti、V、Mn、Fe、Co和Ni中的一种或多种，B′为Ti、V、Mn、Fe、Co和Ni中的一种或多种，y为0～1之间的任意数值。一种实施方式中，A为Mn，B为Fe，含锂磷酸盐微米级颗粒具有LiMnxFe1-xPO4的化学式，x为0～1的任意数值；A′为Mn，B′为Fe，含锂磷酸盐纳米级颗粒具有LiMnyFe1-yPO4的化学式，y为0～1的任意数值。上述实施方式，有利于提高电池的倍率性能。
本公开第二方面提供一种含锂磷酸盐材料的制备方法，所述制备方法包括如下步骤：
(1)将第一锂源、第一金属源和第一磷源混合，对所得混合物进行第一预烧结，得到第一预烧结产物；将所述第一预烧结产物、第一碳源和造孔剂进行第一二次烧结，对所述第一二次烧结产物进行第一破碎处理或第一造粒处理，得到含锂磷酸盐微米级颗粒；
将第二锂源、第二金属源和第二磷源混合，对所得混合物进行第二预烧结，得到第二预烧结产物；将所述第二预烧结产物和第二碳源进行第二二次烧结，对所述第二二次烧结产物进行第二破碎处理或第二造粒处理，得到含锂磷酸盐纳米级颗粒；
(2)将所述含锂磷酸盐纳米级颗粒和所述含锂磷酸盐微米级颗粒进行混合。
本公开的制备方法能提供较多的反应活性位点，提高正极材料的孔隙率，为电解液提供锂离子的传输通道；同时通过纳米级颗粒和微米级颗粒的适宜级配提高正极材料层的压实密度，进一步提高锂离子电池的可逆容量，提升电池的倍率性能。
根据本公开，含锂磷酸盐微米级颗粒与含锂磷酸盐纳米级颗粒的组成可以相同或不同。本领域技术人员可以理解，在纳米级颗粒与微米级颗粒组成相同的实施方式中，也可以将制备第一预烧结产物和制备第二预烧结产物的步骤合并，例如将得到的第一预烧结产物的一部分用于第一二次烧结来制备微米级颗粒，将另一部分的第一预烧结产物用于第二二次烧结来制备纳米级颗粒。
根据本公开，所述第一锂源和第二锂源各自独立地为含锂元素的化合物，在本公开的一种实施方式中，所述含锂元素的化合物可以选自碳酸锂、碳酸氢锂、磷酸二氢锂、氢氧化锂和草酸锂中的一种或多种。
根据本公开的一种实施方式，所述第一金属源和第二金属源各自独立地为含有Ti、V、Mn、Fe、Co和Ni中的一种或多种元素的化合物；含Ti元素的化合物可以选自二氧化钛、四氯化钛、硝酸钛、四烷氧基钛和酰基钛中的一种或多种；含V元素的化合物可以选自五氧化二钒、偏钒酸铵和草酸氧钒中的一种或多种；含Mn元素的化合物可以选自碳酸锰、硫酸亚锰、磷酸锰、硝酸锰和氧化锰中的一种或多种；含Fe元素的化合物可以选自氧化亚铁、氧化铁、草酸铁和乙酸亚铁中的一种或多种；含Co元素的化合物可以选自氧化钴、碳酸钴、氯化钴和乙酸钴中的一种或多种；含Ni元素的化合物可以选自氧化镍、碳酸镍、氯化镍和乙酸镍中的一种或多种。
根据本公开的一种实施方式，所述第一磷源和第二磷源可以各自独立地选自磷酸、磷酸二氢铵、磷酸一氢铵和磷酸二氢锂中的一种或多种。
根据本公开的一种实施方式，所述第一碳源和第二碳源可以各自独立地选自有机碳源和/或无机碳源，进一步可以选自蔗糖、葡萄糖、柠檬酸、酚醛树脂、淀粉和碳黑中的一种或多种。
根据本公开的一种实施方式，所述造孔剂为易分解为气体的物质，可以使材料中产生孔洞结构，所述造孔剂可以选自乙醇、草酸、碳酸氢铵、碳酸铵、尿素和氯化铵中的一种或多种。上述实施方式，有利于使微米级颗粒具有孔道结构，为锂离子传输提供通道，使锂离子电池可逆容量高，电池的倍率性能更好。
进一步的实施方式中，步骤(1)中，所述造孔剂的质量占所述第一预烧结产物和造孔剂总质量的1～5％，优选为3％～5％。上述实施方式，有利于形成具有更适宜的尺寸和数量孔道的含锂磷酸盐微米级颗粒，为电解液提供锂离子的传输通道，使锂离子电池可逆容量高，电池的倍率性能更好；另一方面，有利于纳米级颗粒的嵌入，降低材料的比表面积，进而降低原料吸水程度，在混料制浆过程中，可以减少纳米颗粒的团聚，有利于粘结剂和导电剂的均一分布，抑制其交联导致凝胶。
在本公开中，第一/第二锂源、第一/第二金属源和第一/第二磷源的用量不作特殊限定，本领域技术人员可以根据所制备的含锂磷酸盐材料的化学式中各元素的化学计量比进行投料。本公开对步骤(1)中制备含锂磷酸盐微米级颗粒和含锂磷酸盐纳米级颗粒的先后顺序不作特殊限定，例如本领域技术人员可以先制备含锂磷酸盐微米级颗粒，也可以先制备含锂磷酸盐纳米级颗粒。
根据本公开的一种实施方式，步骤(1)中，所述第一预烧结的条件包括：在保护气体下进行，所述保护气体包括氮气、氩气、氦气和氢气中的一种或多种；预烧结温度为500～650℃，优选为550～600℃，预烧结时间为2～6h，优选为2～4h。上述实施方式，有利于形成适宜尺寸和适宜孔道的微米级颗粒，提供锂离子传输通道，进一步提高电池的倍率性能。
根据本公开的一种实施方式，步骤(1)中，所述第一二次烧结的条件包括：在保护气体下进行，所述保护气体包括氮气、氩气、氦气和氢气中的一种或多种；烧结温度为710～900℃，优选为750～850℃，烧结时间为6～12h，优选为8～10h。上述实施方式，有利于形成适宜尺寸和适宜孔道的微米级颗粒，提供锂离子传输通道，进一步提高电池的倍率性能。
根据本公开的一种实施方式，通过第一破碎处理使第一二次烧结产物形成为含锂磷酸盐微米级颗粒，第一破碎处理的条件可以为本领域常规的能够使烧结产物成为微米级颗粒的条件，进一步的实施方式，所述第一破碎处理的条件包括：使用球磨机对所述第一二次烧结产物进行破碎，球磨转速为400～500r/min，优选为420～480r/min，球磨时间为8～10h，优选为8.5～9.5h。上述实施方式，有利于形成适宜尺寸和适宜孔道的微米级颗粒，提供锂离子传输通道，进一步提高电池的倍率性能。
根据本公开的另一种实施方式，通过第一造粒处理使第一二次烧结产物形成为微米级颗粒，第一造粒处理的条件可以为本领域常规的能够使烧结产物成为微米级颗粒的条件，进一步的实施方式，所述第一造粒处理的条件包括：进料气压为0.8～1.2MPa，优选为0.9～1.1MPa，惰性保护气体流量为30～50L/min，优选为40～45L/min，气体预热温度为100～150℃，优选为120～140℃，进料固含量为45～55％，优选为48～52％。进一步的实施方式中，所述第一造粒处理包括将所述第一二次烧结产物与溶剂混合得到固含量为45～55％的浆液，对所述浆液进行第一造粒处理；使用的溶剂可以为水或无水乙醇。上述实施方式，有利于形成适宜尺寸和适宜孔道的微米级颗粒，提供锂离子传输通道，进一步提高电池的倍率性能。
根据本公开的一种实施方式，步骤(1)中，所述第二预烧结的条件包括：在保护气体下进行，所述保护气体包括氮气、氩气、氦气和氢气中的一种或多种；预烧结温度为500～650℃，优选为550～600℃，预烧结时间为2～6h，优选为2～4h。上述实施方式，有利于形成适宜尺寸的含锂磷酸盐纳米级颗粒，提供反应活性位点，进一步提高电池的倍率性能。
根据本公开的一种实施方式，步骤(1)中，所述第二二次烧结的条件包括：在保护气体下进行，所述保护气体包括氮气、氩气、氦气和氢气中的一种或多种；烧结温度600～700℃，优选为620～680℃，烧结时间为4～8h，优选为6～7h。上述实施方式，有利于形成适宜尺寸的含锂磷酸盐纳米级颗粒，提供反应活性位点，进一步提高电池的倍率性能。
根据本公开的一种实施方式，步骤(1)中，通过第二破碎处理使第二二次烧结产物形成为含锂磷酸盐纳米级颗粒，第一破碎处理的条件可以为本领域常规的能够使烧结产物成为纳米级颗粒的条件，进一步的实施方式，所述第二破碎处理的条件包括：使用球磨机对所述第二二次烧结产物进行破碎，球磨机转速为450～600r/min，球磨时间为10～15h。上述实施方式，有利于形成适宜尺寸的含锂磷酸盐纳米级颗粒，提供反应活性位点，进一步提高电池的倍率性能。
根据本公开的另一种实施方式，通过第二造粒处理使第二二次烧结产物形成为纳米级颗粒，第二造粒处理的条件可以为本领域常规的能够使烧结产物成为纳米级颗粒的条件，进一步的实施方式，所述第二造粒处理的条件包括：进料气压为1～1.5MPa，优选为1.2～1.4MPa，惰性保护气体流量为40～60L/min，优选为45～55L/min，气体预热温度为100～150℃，优选为120～140℃，进料固含量为45～55％，优选为48～52％。进一步的实施方式中，所述第二造粒处理包括将所述第二二次烧结产物与溶剂混合得到固含量为45～55％的浆液，对所述浆液进行第二造粒处理；使用的溶剂可以为水或无水乙醇。上述实施方式，有利于形成适宜尺寸的含锂磷酸盐纳米级颗粒，提供反应活性位点，进一步提高电池的倍率性能。
根据本公开的一种实施方式，步骤(2)中，所述混合为固相混合，且在搅拌的条件下进行，所述搅拌的速率为500～1200rpm，所述混合的温度为25～35℃，所述混合的时间为30～60min。本公开对混合的设备不作具体限制，可以为常规市售产品。上述实施方式，有利于在提供较多的反应活性位点的同时提高正极材料层的压实密度，同时提供适宜数量的孔道，为锂离子提供传输通道，进一步提高电池的倍率性能。
根据本公开的一种实施方式，步骤(2)中，所述含锂磷酸盐纳米级颗粒的D50粒径为0.5～0.9μm，优选为0.6～0.8μm；所述含锂磷酸盐微米级颗粒的D50粒径为2.5～10μm，优选为4～8μm；所述含锂磷酸盐微米级颗粒的D50粒径为含锂磷酸盐纳米颗粒的D50粒径的5～10倍，优选为6～8倍。上述实施方式，有利于提供较多的反应活性位点，同时提供适宜数量的孔道，为锂离子提供传输通道，进一步提高电池的倍率性能。
本公开第三方面提供一种由本公开第二方面所述方法制备的含锂磷酸盐材料。
本公开第四方面提供一种制备锂离子电池正极的方法，所述方法包括：使含锂磷酸盐材料、导电剂、粘结剂和溶剂进行混合形成正极浆料；使所述正极浆料在正极集流体上形成正极浆料层，除去所述正极浆料层中的溶剂，形成包含正极材料层的正极极片；其中，所述含锂磷酸盐材料为本公开第一方面和/或本公开第三方面所述的含锂磷酸盐材料。
本公开使用含锂磷酸盐材料制备正极，其中的纳米级颗粒和微米级颗粒可以提供较多的反应活性位点，且微米级颗粒具有孔道，能够提高正极材料的孔隙率，为电解液提供锂离子的传输通道，二者的适宜级配能够提高正极材料层的压实密度，使锂离子电池的可逆容量高，电池的倍率性能更好。
根据本公开，含锂磷酸盐材料、导电剂、粘结剂、分散剂和溶剂的质量比可以在较大的范围内变化。根据本公开的一种实施方式，所述含锂磷酸盐材料、所述导电剂、所述粘结剂、所述分散剂和所述溶剂的质量比可以为1：(0.02～0.05)：(0.03～0.06)：(0.6～0.8)，优选为1：(0.02～0.03)：(0.04～0.05)：(0.65～0.75)。所述导电剂、粘结剂和溶剂为本领域的技术人员熟知的，例如所述导电剂可以为炭黑、碳纳米管、乙炔黑和石墨烯中的一种或多种；所述粘结剂可以为聚偏氟乙烯(PVDF)、聚乙烯醇(PVA)和聚四氟乙烯(PTFE)中的一种或多种；所述溶剂可以为N-甲基吡咯烷酮、N-甲基甲酰胺、乙醇和丙酮的一种或多种。
根据本公开的一种实施方式，所述正极浆料还包括分散剂，所述分散剂可以为聚乙烯吡咯烷酮(PVP)、聚丙烯酸(PAA)、聚乙烯亚胺(PEI)和丙烯酸-马来酸共聚物(PAMA)中的一种或多种；所述含锂磷酸盐材料与所述分散剂的质量比可以在较大的范围内变化，例如可以为1：(0.01～0.03)，优选为1：(0.015～0.025)。
根据本公开的一种实施方式，该方法还包括：在形成正极浆料层之前，对所述正极浆料进行剪切处理，所述剪切处理的条件包括：剪切速率为4000～8000rpm，优选为5000～7000rpm；所述正极浆料的固含量可以为45～60重量％，优选为50～55重量％；可选的一种实施方式中，所述剪切的温度为20～35℃，优选为25～30℃。本公开的剪切速率为常规剪切速率的1.2～2倍。上述实施方式，有利于使含锂磷酸盐材料颗粒的薄弱部位即嵌入边界受应力作用分裂，使包裹定量辅材的正极材料再分开成纳米级颗粒和微米级颗粒，保证了浆料稳定分散，也保证了正极极片中具有较多的反应活性位点，又通过纳米级颗粒搭配多孔微米级大颗粒提高正极极片的压实密度，暴露出孔道结构为电解液提供锂离子传输通道，进一步提升电池的可逆容量，提高电池的倍率性能。
根据本公开的一种实施方式，所述含锂磷酸盐微米级颗粒和含锂磷酸盐纳米级颗粒的质量比可以在较大范围内变化，例如可以为1：(50～200)，优选为1：(100～150)。上述实施方式，有利于得到级配适宜的正极材料层，有利于在提供较多反应活性位点的同时提供锂离子传输通道，提高正极材料的孔隙率，提高正极材料层的压实密度，进一步提高电池的可逆容量和倍率性能。
根据本公开的一种实施方式，所述正极浆料中还包含正极材料纳米颗粒，进一步地，所述正极材料纳米颗粒与所述含锂磷酸盐材料的质量比为(50～200)：1，优选为(100～150)：1。上述实施方式，有利于得到级配适宜的正极材料层，有利于在提供较多反应活性位点的同时提供锂离子传输通道，提高正极材料的孔隙率，提高正极材料层的压实密度，进一步提高电池的可逆容量和倍率性能。
进一步的一种具体实施方式，正极材料纳米颗粒可以在制备浆料的步骤加入。
另一种进一步的具体实施方式，可以在制备含锂磷酸盐材料时一并加入正极材料纳米颗粒，例如，在纳米级颗粒和微米级颗粒混合步骤中加入正极材料纳米颗粒。在正极材料纳米颗粒的组成与纳米级颗粒组成相同的实施方式中，可以直接按照所述正极材料纳米颗粒与所述含锂磷酸盐材料的质量比为(50～200):1的比例制备纳米级颗粒和微米级颗粒。上述实施方式，有利于在混料制浆过程中减少纳米颗粒团聚的机率，利于粘结剂和导电剂的分散均匀，使各组分均一分布，抑制其交联导致凝胶；有利于正极材料纳米颗粒与含锂磷酸盐材料适宜级配，在提供较多反应活性位点的同时提高正极材料层的压实密度，进一步提高电池的可逆容量和倍率性能。
本公开第五方面提供一种由本公开第四方面所述方法制得的锂离子电池正极。
本公开第六方面提供一种锂离子电池正极，所述正极包括正极集流体和设置在所述正极集流体至少一侧的正极材料层，所述正极材料层含有含锂磷酸盐材料；其中所述含锂磷酸盐材料为本公开第一方面和/或本公开第三方面所述的含锂磷酸盐材料。本公开正极的正极材料层内分布有表面多孔的微米级颗粒和纳米级颗粒，保证反应活性位点多的同时，通过纳米级颗粒搭配多孔微米级大颗粒提高正极极片的压实密度和孔隙率，进一步提升电池的可逆容量和电池的倍率性能。
在一种具体实施方式中，所述正极包括正极集流体和设置在所述正极集流体两侧的正极材料层。
根据本公开的一种实施方式，所述正极材料层内还含有正极材料纳米颗粒；所述正极材料纳米颗粒与所述含锂磷酸盐材料的质量比可以在较大的范围内变化，例如可以为(50～200)：1，优选为(100～150)：1。这一实施方式中，正极材料纳米颗粒的组成可以与含锂磷酸盐材料纳米级颗粒相同或不同，进一步地，所述正极材料纳米颗粒具有化学式LiA″zB″1-zPO4表示的组成，其中，A″为Ti、V、Mn、Fe、Co和Ni中的一种或多种，B″为Ti、V、Mn、Fe、Co和Ni中的一种或多种，z为0～1之间的任意数值。上述实施方式，有利于正极材料纳米颗粒与含锂磷酸盐材料适宜级配，在提供较多反应活性位点的同时提高正极材料层的压实密度，进一步提高电池的可逆容量和倍率性能。
进一步的实施方式中，所述正极材料层的孔隙率为15～25％，优选为17～20％。上述实施方式，有利于提高正极材料层的孔隙率，为电解液提供锂离子传输通道，提高电池的锂离子电池的倍率性能。
本公开第七方面提供一种锂离子电池，包括本公开第五方面和/或本公开第六方面所述的锂离子电池正极。
本公开第八方面提供一种用电装置，包括本公开第七方面的锂离子电池。所述用电装置可以包括但不限于移动通讯设备、汽车、电器等。
下面通过实施例来进一步说明本公开，但是本公开并不因此而受到任何限制。
以下实施例和对比例用于制备磷酸锰铁锂含锂磷酸盐材料为例，其中LiMnxFe1-xPO4中x＝0.8。实施例和对比例中所用原料和试剂均为电池级；若无特殊说明，下述实施例和对比例中使用的化学试剂为商购产品。
本公开中，复合颗粒的比表面积是在型号为TriStarⅡ3020的气体吸附仪上使用BET法进行测试；复合颗粒的孔隙率、含锂磷酸盐材料的孔隙率、正极材料层的孔隙率以及微米级颗粒的D50孔径是在型号为ZEISS Crossbeam 550的聚焦离子束扫描电子显微镜上进行测试的；微米级颗粒的D50粒径和纳米级颗粒的D50粒径是在型号为PSA200702的激光粒度分析仪上测试的。正极浆料的粘度测试通过在型号为ViscoQC 300(L)的旋转流变仪上进行测试。
实施例1
(1)按化学计量比，将摩尔比为0.5:0.8:0.1:1的碳酸锂、氧化铁、碳酸锰、磷酸二氢铵进行球磨搅拌直至混合均匀，将上述混合后的原料加入高温烧结炉中，通入氩气，预烧结温度维持在600℃，持续烧结2小时，得到第一预烧结产物；
将静置冷却后的第一预烧结产物倒入球磨机，并加入葡萄糖进行球磨直至分均匀散后，再添加第一预烧结产物和碳酸氢铵总重量的3重量％的碳酸氢铵进行混合，将混合造孔剂的粉料再次放入烧结炉中进行第一二次烧结，温度为750℃，烧结8小时，然后将第一二次烧结后的产物与无水乙醇混合得到固含量为50％的浆液，对浆液进行喷雾造粒处理，进料气压为1MPa，氩气流量为40L/min，氩气预热温度为120℃，得到多孔微米级LMFP颗粒，D50粒径为4μm，D50孔径为0.6μm；
按化学计量比，将摩尔比为0.5:0.8:0.1:1的碳酸锂、氧化铁、碳酸锰、磷酸二氢铵进行球磨搅拌直至混合均匀，将上述混合后的原料加入高温烧结炉中，通入氩气，预烧结温度维持在600℃，持续烧结2小时，得到第二预烧结产物；将静置冷却后的第二预烧结产物倒入球磨机，并加入葡萄糖进行球磨直至分均匀散后，将混合葡萄糖的粉料再次放入烧结炉中进行第二二次烧结，温度为650℃，烧结6小时，然后将第二二次烧结后的产物与无水乙醇混合得到固含量为50％的浆液，对浆液进行喷雾造粒处理，进料气压为1.2MPa，氩气流量为50L/min，得到纳米级LMFP颗粒，氩气预热温度为120℃，纳米级LMFP颗粒的D50粒径为0.65μm；
(2)将上述得到的多孔微米级颗粒和纳米级颗粒以1:100的质量比进行搅拌混合，通过混合使大部分纳米级颗粒进入微米颗粒的孔道内形成复合颗粒，混合温度为25℃，混合时间为40min，搅拌速率为800rpm；
(3)将上述复合颗粒同导电剂CNT、粘结剂PVDF、分散剂PVP和溶剂NMP按质量比为1：0.02：0.04：0.02:0.7混合形成正极浆料，正极浆料的固含量为50重量％；然后对正极浆料进行剪切，剪切速率为6000rpm，在25℃下剪切，搅拌20分钟后，将剪切后的浆料涂覆于集流体上，浆料在集流体上形成正极浆料层，剪切时部分纳米级颗粒脱离微米级颗粒的孔道，得到的剪切后的正极浆料中包含具有嵌入结构的含锂磷酸盐材料以及分散的正极材料纳米颗粒；除去正极浆料层中的溶剂，形成包含正极材料层的正极极片，并与隔膜、石墨负极等组装成全电池进行测试。
实施例2
与实施例1相同，区别在于，步骤(1)中造孔剂碳酸氢铵的质量比例为1％。
实施例3
与实施例1相同，区别在于，步骤(1)中制备多孔微米级颗粒的条件不同，具体如下：
将静置冷却的第一预烧结产物倒入球磨机，并加入葡萄糖进行球磨直至分均匀散后，再添加第一预烧结产物和碳酸氢铵总重量的3重量％的碳酸氢铵进行混合，将混合造孔剂的粉料再次放入烧结炉中进行第一二次烧结，温度为850℃，烧结6小时，将第一二次烧结后的产物与无水乙醇混合得到固含量为50％的浆液，对浆液进行喷雾造粒处理，进料气压为1MPa，氩气流量为40L/min，氩气预热温度为120℃，得到多孔微米级LMFP颗粒，微米级颗粒的D50粒径为4μm，D50孔径为0.5μm。
实施例4
与实施例1相同，区别在于，步骤(1)中制备多孔微米级颗粒的条件不同，具体如下：
将静置冷却的第一预烧结产物倒入球磨机，并加入葡萄糖进行球磨直至分均匀散后，再添加第一预烧结产物和碳酸氢铵总重量的3重量％的碳酸氢铵进行混合，将混合造孔剂的粉料再次放入烧结炉中进行第一二次烧结，温度为750℃，烧结8小时，然后将第一二次烧结后的产物与无水乙醇混合得到固含量为50％的浆液，对浆液进行喷雾造粒处理，进料气压为1.3MPa，氩气流量为52L/min，氩气预热温度为120℃，得到多孔微米级LMFP颗粒，微米级颗粒D50粒径为3μm，D50孔径为0.6μm。
实施例5
与实施例1相同，区别在于，步骤(2)中，多孔微米级颗粒和纳米级颗粒混合的质量比为1:50。
实施例6
与实施例1相同，区别在于，步骤(3)中，剪切速率为4800rpm。
实施例7
与实施例1相同，区别在于，步骤(1)中，制备纳米级颗粒时进料气压为1MPa，氩气流量为40L/min，氩气预热温度为120℃，纳米级LMFP颗粒的D50粒径为0.9μm。
实施例8
与实施例1相同，区别在于，步骤(1)中，制备微米级颗粒时：第一二次烧结温度为900℃，烧结12小时；进料气压为0.8MPa，氩气流量为30L/min，氩气预热温度为120℃，得到微米级LMFP颗粒的D50粒径为10μm，D50孔径为0.6μm。
实施例9
与实施例1相同，区别在于，步骤(1)中，制备纳米级颗粒时：第二二次烧结的温度为600℃，烧结4h；进料气压为1.5MPa，氩气流量为60L/min，氩气预热温度为120℃，得到纳米级LMFP颗粒的D50粒径为0.5μm。
对比例1
按化学计量比，将摩尔比为0.5:0.8:0.1:1的碳酸锂、氧化铁、碳酸锰、磷酸二氢铵进行球磨搅拌直至混合均匀，将上述混合后的原料加入高温烧结炉中，通入氩气，预烧结温度维持在600℃，持续烧结2小时，得到预烧结产物；将静置冷却的预烧结产物倒入球磨机，并加入葡萄糖进行球磨直至分均匀散后，将粉料再次放入烧结炉中进行二次烧结，温度为650℃，烧结6小时，然后将二次烧结后的产物与无水乙醇混合得到固含量为50％的浆液，对浆液进行喷雾造粒处理，进料气压为1.2MPa，氩气流量为50L/min，氩气预热温度为120℃，得到纳米级LMFP颗粒，D50粒径为0.65μm；将纳米级LMFP颗粒与导电剂CNT、粘结剂PVDF、分散剂PVP和溶剂NMP按质量比为1：0.02：0.04：0.02:0.7配制成浆料，涂覆与集流体上，并与隔膜、石墨负极等组装成全电池进行测试。
对比例2
本对比例的方法与实施例1相同，区别在于步骤(1)中不加造孔剂碳酸氢铵，具体如下：
(1)按化学计量比，将摩尔比为0.5:0.8:0.1:1的碳酸锂、氧化铁、碳酸锰、磷酸二氢铵进行球磨搅拌直至混合均匀，将上述混合后的原料加入高温烧结炉中，通入氩气，预烧结温度维持在600℃，持续烧结2小时，得到第一预烧结产物；将静置冷却的第一预烧结产物倒入球磨机，并加入葡萄糖进行球磨直至分均匀散后，将粉料再次放入烧结炉中进行二次烧结，温度为750℃，烧结8小时，然后将二次烧结后的产物与无水乙醇混合得到固含量为50％的浆液，对浆液进行喷雾造粒处理，进料气压为1MPa，氩气流量为40L/min，氩气预热温度为120℃，得到无孔的微米级LMFP颗粒，D50粒径为4μm；
按化学计量比，将摩尔比为0.5:0.8:0.1:1的碳酸锂、氧化铁、碳酸锰、磷酸二氢铵进行球磨搅拌直至混合均匀，将上述混合后的原料加入高温烧结炉中，通入氩气，预烧结温度维持在600℃，持续烧结2小时，得到第二预烧结产物；将静置冷却的第二预烧结产物倒入球磨机，并加入葡萄糖进行球磨直至分均匀散后，将混合葡萄糖的粉料再次放入烧结炉中进行二次烧结，温度为650℃，烧结6小时，然后将二次烧结后的产物与无水乙醇混合得到固含量为50％的浆液，对浆液进行喷雾造粒处理，条件进料气压为1.2MPa，氩气流量为50L/min，氩气预热温度为120℃，得到纳米级LMFP颗粒，纳米级LMFP颗粒的D50粒径为0.65μm；
(2)将上述得到的无孔微米级颗粒和纳米级颗粒以1:100的质量比进行搅拌混合后获得包含无孔微米级颗粒和纳米级颗粒的混合颗粒，混合温度为25℃，搅拌速率为800rpm；
(3)将上述复合颗粒同导电剂CNT、粘结剂PVDF、分散剂PVP和溶剂NMP按质量比为1：0.02：0.04：0.02:0.7进行混合形成正极浆料；然后对正极浆料进行剪切，剪切速率为6000rpm，正极浆料的固含量为50重量％，在25℃下剪切，搅拌20分钟后，将剪切后的浆料涂覆于集流体上，浆料在集流体上形成正极浆料层，除去正极浆料层中的溶剂，形成包含正极材料层的正极极片，并与隔膜、石墨负极等组装成全电池进行测试。
测试例1
对实施例1～9、对比例1～2得到的微米级颗粒的D50粒径、D50孔径、纳米级颗粒的D50粒径、复合颗粒的比表面积和孔隙率、含锂磷酸盐材料的比表面积、正极材料层的孔隙率进行测试；测试结果如表1所述。
本公开中对含锂磷酸盐材料的表征是对剪切后的浆料进行过滤、干燥和筛分等处理后的颗粒进行的测试。
表1中实施例1～9的复合颗粒的比表面积是指步骤(2)通过混合得到的复合颗粒的比表面积。
本公开中复合颗粒的孔隙率是指单颗复合颗粒内部孔隙的体积占总体积的百分比。表1中实施例1～9复合颗粒的孔隙率测试的是步骤(2)通过混合得到的复合颗粒的孔隙率。
含锂磷酸盐材料的孔隙率是指单颗颗粒内部孔隙的体积占总体积的百分比。
正极材料层的孔隙率是指单位块状正极材料层中孔隙体积与正极材料在自然状态下总体积的百分比。
表1
对比例2中经过步骤(2)得到的含有无孔微米级颗粒与纳米级颗粒的混合颗粒的比表面积为18.6m2/g，根据表1的数据可知，相比对比例2，实施例1中经过步骤(2)的混合得到的复合颗粒的比表面积更小，说明混合过程中，纳米级颗粒嵌入到微米级颗粒的孔道内；根据实施例1中复合颗粒的孔隙率与含锂磷酸盐材料的孔隙率对比可知，经过步骤(3)的剪切处理，剪切后的含锂磷酸盐材料的孔隙率高于复合颗粒的孔隙率，说明通过剪切使部分纳米级颗粒从微米级颗粒的孔道中脱落。
测试例2
对实施例1～9和对比例1～2剪切后的正极浆料的状态进行观察，在出料0h、2h、8h和12h分别对浆料的粘度进行测试，若浆料粘度超过3500mPa·s即定义浆料形成凝胶，若在12h内粘度不超过3500mPa·s，则判定浆料状态良好；结果如表2。
表2
测试例3
对实施例1～9和对比例1～2组装的全电池进行倍率性能的测试，测试方法为在常温条件下，1/3C恒流恒压充/放电，测试结果如表3。
表3

对比例1纳米级颗粒的比表面积为21m2/g，根据表1、表2和表3的数据可知，相比于对比例1，本公开方法制备的含锂磷酸盐材料的比表面积小，用于制备锂离子电池正极极片时，可以降低正极原料的吸水程度；在混料制浆过程中，可以减少颗粒团聚的机率，有利于粘结剂和导电剂的分散均匀，抑制其交联导致凝胶，保证了浆料稳定分散，又通过纳米级颗粒搭配多孔微米级大颗粒提高正极材料的压实密度，暴露出微米级颗粒的孔道结构为电解液提供锂离子传输通道，进一步提升电池的可逆容量，提高电池的倍率性能。
实施例1～7与对比例1相比可知，本公开的正极浆料颗粒团聚现象少，正极浆料在4h以内不会形成凝胶；对比例1在1h出现严重凝胶，形成连续颗粒团聚，显著影响电池的离子传输速率。对比例2未加入造孔剂，相较于实施例1，其总体颗粒比表面积增大，进一步增大吸水率以及与粘结剂交联反应面积，所制成的浆料在2h内形成凝胶，且微米级颗粒无孔道结构，导致固相锂离子传输距离延长，倍率性能差。
实施例2与实施例1相比，实施例1中造孔剂含量在本公开优选的范围内，使得微米级颗粒能更好地形成多孔结构，更有利于嵌入纳米级颗粒，降低吸水概率，避免浆料出现凝胶。类似地，实施例3与实施例1相比可知，实施例1中微米级颗粒的D50孔径与纳米级颗粒的D50粒径的比值在本公开的优选范围，更有利于纳米级颗粒嵌入微米级颗粒的孔径中，避免造成团聚现象，更有利于提高电池的倍率性能。实施例4与实施例1相比可知，实施例1的微米级颗粒的D50粒径与纳米级颗粒的D50粒径的比值在本公开的优选范围，避免浆料在4h内出现凝胶，更有利于提高电池的倍率性能。实施例5与实施例1相比，实施例1中多孔微米级颗粒和纳米级颗粒的级配优于实施例5，更有利于提高活性位点，进一步提高电池的倍率性能。实施例6与实施例1相比，实施例1的剪切速率在本公开的优选范围，有利于纳米级颗粒更好地与微米级颗粒分离，有利于提高电池的倍率性能。实施例7与实施例1相比，实施例1的微米级颗粒的D50粒径与纳米级颗粒的D50粒径的比值、微米级颗粒的D50孔径与纳米级颗粒的D50粒径的比值在本公开的优选范围，更有利于纳米级颗粒嵌入微米级颗粒的孔径中，避免造成团聚现象，有利于提高电池的倍率性能。实施例8与实施例1相比，实施例1的微米级颗粒的D50粒径与纳米级颗粒的D50粒径的比值在本公开的优选范围，有利于提高正极材料层的孔隙率，利于锂离子传输，电池的倍率性能更好。实施例9与实施例1相比，实施例1的微米级颗粒的D50孔径与纳米级颗粒的D50粒径的比值在本公开的优选范围，避免造成团聚现象同时避免浆料在4h内凝胶，更有利于提高电池的倍率性能。
以上详细描述了本公开的优选实施方式，但是，本公开并不限于上述实施方式中的具体细节，在本公开的技术构思范围内，可以对本公开的技术方案进行多种简单变型，这些简单变型均属于本公开的保护范围。
另外需要说明的是，在上述具体实施方式中所描述的各个具体技术特征，在不矛盾的情况下，可以通过任何合适的方式进行组合。为了避免不必要的重复，本公开对各种可能的组合方式不再另行说明。

Claims (24)

  1. 一种含锂磷酸盐材料，其特征在于，所述含锂磷酸盐材料包括表面具有孔道的含锂磷酸盐微米级颗粒，所述含锂磷酸盐微米级颗粒的孔道内嵌有含锂磷酸盐纳米级颗粒。
  2. 根据权利要求1所述的含锂磷酸盐材料，其中，所述含锂磷酸盐微米级颗粒的D50粒径与所述含锂磷酸盐纳米级颗粒的D50粒径的比值为5～10。
  3. 根据权利要求1或2所述的含锂磷酸盐材料，其中，所述含锂磷酸盐微米级颗粒的孔道的D50孔径与所述含锂磷酸盐纳米级颗粒的D50粒径的比值为0.8～1。
  4. 根据权利要求1～3中任意一项所述的含锂磷酸盐材料，其中，所述含锂磷酸盐纳米级颗粒的D50粒径为0.5～0.9μm。
  5. 根据权利要求1～4中任意一项所述的含锂磷酸盐材料，其中，所述含锂磷酸盐微米级颗粒的D50粒径为2.5～10μm，所述孔道的D50孔径为0.4～0.9μm。
  6. 根据权利要求1～5中任意一项所述的含锂磷酸盐材料，其中，所述含锂磷酸盐材料的孔隙率为10～15％。
  7. 根据权利要求1～6中任意一项所述的含锂磷酸盐材料，其中，
    所述含锂磷酸盐微米级颗粒具有化学式LiAxB1-xPO4表示的组成，其中，A为Ti、V、Mn、Fe、Co和Ni中的一种或多种，B为Ti、V、Mn、Fe、Co和Ni中的一种或多种，x为0～1之间的任意数值；
    所述含锂磷酸盐纳米级颗粒具有化学式LiA′yB′1-yPO4表示的组成，其中，A′为Ti、V、Mn、Fe、Co和Ni中的一种或多种，B′为Ti、V、Mn、Fe、Co和Ni中的一种或多种，y为0～1之间的任意数值。
  8. 一种含锂磷酸盐材料的制备方法，其特征在于，所述制备方法包括如下步骤：
    (1)将第一锂源、第一金属源和第一磷源混合，对所得混合物进行第一预烧结，得到第一预烧结产物；将所述第一预烧结产物、第一碳源和造孔剂进行第一二次烧结，对所述第一二次烧结产物进行第一破碎处理或第一造粒处理，得到含锂磷酸盐微米级颗粒；
    将第二锂源、第二金属源和第二磷源混合，对所得混合物进行第二预烧结，得到第二预烧结产物；将所述第二预烧结产物和第二碳源进行第二二次烧结，对所述第二二次烧结产物进行第二破碎处理或第二造粒处理，得到含锂磷酸盐纳米级颗粒；
    (2)将所述含锂磷酸盐纳米级颗粒和所述含锂磷酸盐微米级颗粒进行混合。
  9. 根据权利要求8所述的制备方法，其中，所述第一金属源和第二金属源各自独立地为含有Ti、V、Mn、Fe、Co和Ni中的一种或多种元素的化合物；所述第一碳源和第二碳源各自独立地选自蔗糖、葡萄糖、柠檬酸、酚醛树脂、淀粉和碳黑中的一种或多种。
  10. 根据权利要求8或9所述的制备方法，其中，步骤(1)中，所述造孔剂的质量占所述第一预烧结产物和造孔剂总质量的1～5％；所述造孔剂选自乙醇、草酸、碳酸氢铵、碳酸铵、尿素和氯化铵中的一种或多种。
  11. 根据权利要求8-10中任意一项所述的制备方法，其中，步骤(1)中，所述第一预烧结的条件包括：在保护气体下进行，预烧结温度为500～650℃，预烧结时间为2～6h；
    所述第一二次烧结的条件包括：在保护气体下进行，烧结温度为710～900℃，烧结时间为6～12h；
    所述第一破碎处理的条件包括：使用球磨机对所述第一二次烧结产物进行破碎，球磨机转速为400～500r/min，球磨时间为8～10h；
    所述第一造粒处理的条件包括：进料气压为0.8～1.2MPa，惰性保护气体流量为30～50L/min，气体预热温度为100～150℃，进料固含量为45～55％。
  12. 根据权利要求8-11中任意一项所述的制备方法，其中，步骤(1)中，所述第二预烧结的条件包括：在保护气体下进行，预烧结温度为500～650℃，预烧结时间为2～6h；
    所述第二二次烧结的条件包括：在保护气体下进行，烧结温度为600～700℃，烧结时间为4～8h；
    所述第二破碎处理的条件包括：使用球磨机对所述第二二次烧结产物进行破碎，球磨机转速为450～600r/min，球磨时间为10～15h；
    所述第二造粒处理的条件包括：进料气压为1～1.5MPa，惰性保护气体流量为40～60L/min，气体预热温度为100～150℃，进料固含量为45～55％。
  13. 根据权利要求8-12中任意一项所述的制备方法，其中，步骤(2)中，所述混合为固相混合，且在搅拌的条件下进行，所述搅拌的速率为500～1200rpm，所述混合的温度为25～35℃，所述混合的时间为30～60min。
  14. 根据权利要求8-13中任意一项所述的制备方法，其中，步骤(2)中，所述含锂磷酸盐纳米级颗粒的D50粒径为0.5～0.9μm；所述含锂磷酸盐微米级颗粒的D50粒径为2.5～10μm；所述含锂磷酸盐微米级颗粒的D50粒径为含锂磷酸盐纳米颗粒的D50粒径的5～10倍。
  15. 采用权利要求8～14中任意一项所述的制备方法制备的含锂磷酸盐材料。
  16. 一种制备锂离子电池正极的方法，其特征在于，所述方法包括：使含锂磷酸盐材料、导电剂、粘结剂和溶剂进行混合形成正极浆料；使所述正极浆料在正极集流体上形成正极浆料层，除去所述正极浆料层中的溶剂，形成包含正极材料层的正极极片；
    其中，所述含锂磷酸盐材料为权利要求1～7和权利要求15中任意一项所述的含锂磷酸盐材料。
  17. 根据权利要求16所述的方法，其中，该方法还包括：在形成正极浆料层之前，对所述正极浆料进行剪切处理，所述剪切处理的条件包括：剪切速率为4000～8000rpm，所述剪切处理的温度为20～35℃。
  18. 根据权利要求16或17所述的方法，其中，所述含锂磷酸盐微米级颗粒和含锂磷酸盐纳米级颗粒的质量比为1：(50～200)。
  19. 权利要求16～18中任意一项所述的制备方法制得的锂离子电池正极。
  20. 一种锂离子电池正极，其特征在于，包括正极集流体和设置在所述正极集流体至少一侧的正极材料层；所述正极材料层含有含锂磷酸盐材料；
    其中，所述含锂磷酸盐材料为权利要求1～7和权利要求15中任意一项所述的含锂磷酸盐材料。
  21. 根据权利要求20所述的锂离子电池正极，其中，所述正极材料层的孔隙率为15～25％。
  22. 根据权利要求20或21所述的锂离子电池正极，其中，所述正极材料层还含有正极材料纳米颗粒；
    所述正极材料纳米颗粒具有化学式LiA″zB″1-zPO4表示的组成，其中，A″为Ti、V、Mn、Fe、Co和Ni中的一种或多种，B″为Ti、V、Mn、Fe、Co和Ni中的一种或多种，z为0～1之间的任意数值；
    所述正极材料纳米颗粒与所述含锂磷酸盐材料的质量比为(50～200):1。
  23. 一种锂离子电池，其特征在于，包括权利要求19～22中任意一项所述的锂离子电池正极。
  24. 一种用电装置，其特征在于，包括权利要求23所述的锂离子电池。
PCT/CN2025/078635 2024-06-19 2025-02-21 一种含锂磷酸盐材料、锂离子电池正极及制备方法与应用 Pending WO2025260808A1 (zh)

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