WO2024259587A1 - 一种磷酸锰铁锂正极材料、极片及其制备方法和应用 - Google Patents

一种磷酸锰铁锂正极材料、极片及其制备方法和应用 Download PDF

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WO2024259587A1
WO2024259587A1 PCT/CN2023/101395 CN2023101395W WO2024259587A1 WO 2024259587 A1 WO2024259587 A1 WO 2024259587A1 CN 2023101395 W CN2023101395 W CN 2023101395W WO 2024259587 A1 WO2024259587 A1 WO 2024259587A1
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Prior art keywords
positive electrode
phosphate
lithium
preparation
lithium iron
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PCT/CN2023/101395
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English (en)
French (fr)
Inventor
吴星宇
阮丁山
冯茂华
张静静
刘宝烨
李长东
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Hunan Brunp Recycling Technology Co Ltd
Guangdong Brunp Recycling Technology Co Ltd
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Hunan Brunp Recycling Technology Co Ltd
Guangdong Brunp Recycling Technology Co Ltd
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Application filed by Hunan Brunp Recycling Technology Co Ltd, Guangdong Brunp Recycling Technology Co Ltd filed Critical Hunan Brunp Recycling Technology Co Ltd
Priority to PCT/CN2023/101395 priority Critical patent/WO2024259587A1/zh
Priority to CN202380009514.0A priority patent/CN117015871A/zh
Publication of WO2024259587A1 publication Critical patent/WO2024259587A1/zh
Anticipated expiration legal-status Critical
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    • 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 relates to the technical field of lithium batteries, and in particular to a lithium manganese iron phosphate positive electrode material, a pole piece, and a preparation method and application thereof.
  • lithium-ion batteries as energy storage materials have the advantages of high voltage, large specific capacity, long cycle life and good safety performance compared to traditional batteries, and are widely used in portable electronic devices, electric vehicles, aerospace and military engineering. In order to be used in electric vehicles and other fields that require higher energy density, it is necessary to develop new materials for high-performance commercial application of cathode materials.
  • Lithium iron phosphate (LiFePO 4 , LFP) is a positive electrode material with an olivine structure, and its platform voltage is low (3.3V, Li/Li + ), and the energy density of the material is relatively low.
  • Lithium manganese iron phosphate (LiMn x Fe 1-x PO 4 , LMFP) material which also has an olivine structure, has similar high safety performance as lithium iron phosphate material, a higher discharge platform (4.1V, Li + /Li), abundant reserves of phosphorus iron manganese, and is green and pollution-free. However, due to its weak cycle stability and low electronic conductivity, its further commercial application is limited.
  • the purpose of the present disclosure includes providing a lithium iron manganese phosphate positive electrode material, a pole piece, and a preparation method and application thereof, aiming to make the material have high electrical conductivity and good electrochemical performance under high voltage.
  • the solution provided by the present disclosure includes a lithium iron manganese phosphate positive electrode material, including a lithium iron manganese phosphate substrate, a carbon layer coated on the lithium iron manganese phosphate substrate, and the lithium iron manganese phosphate positive electrode material contains a superionic conductor;
  • the superionic conductor is at least one selected from titanium zirconium phosphate, titanium yttrium phosphate, vanadium zirconium phosphate and vanadium yttrium phosphate.
  • the surface of the lithium manganese iron phosphate substrate is also coated with a carbon layer, part of the superionic conductor and the carbon layer are co-coated on the surface of the lithium manganese iron phosphate substrate, and part of the superionic conductor is distributed inside the lithium manganese iron phosphate substrate.
  • the mass fraction of the superionic conductor in the lithium manganese iron phosphate positive electrode material is It is 0.25%-6.0%.
  • the carbon content in the lithium manganese iron phosphate positive electrode material is 1%-3% by mass.
  • the median particle size of the lithium manganese iron phosphate positive electrode material is 0.4 ⁇ m-5.0 ⁇ m, and the specific surface area is 5 m 2 /g-13 m 2 /g.
  • the mass fraction of element A is 0.005%-6%.
  • the solution provided by the present disclosure also includes a method for preparing a lithium manganese iron phosphate positive electrode material, comprising: forming a carbon layer on a lithium manganese iron phosphate substrate, and introducing a superionic conductor
  • the ferromanganese phosphate to be modified, the gel material, the superionic conductor and the lithium source are mixed to obtain a mixed material, the mixed material is heated to dehydrate, and then sintered.
  • the mass ratio of the manganese iron phosphate to be modified, the gel material and the superionic conductor is 100:(2-15):(0.4-8).
  • the gel material is corn starch gel.
  • the heating temperature is controlled to be 110° C.-200° C., and the heating time is 2 h-4 h.
  • heating and dehydration are performed under the condition of passing air, and after completion, the temperature is cooled to room temperature and then ball milling is performed, and then sintering is performed.
  • the sintering temperature is controlled to be 500° C.-1100° C., and the sintering time is 8 h-30 h.
  • the sintering process is carried out under an inert atmosphere. After the sintering is completed, the product is annealed to room temperature and then ball milled and sieved.
  • the preparation process of the mixed material includes: mixing the manganese iron phosphate to be modified, the gel material and the superionic conductor under heating conditions, and then mixing with a lithium source.
  • the heating temperature is controlled to be 50°C-70°C.
  • the molar ratio of the total amount of metal elements in the modified ferromanganese phosphate to the lithium element in the lithium source is (0.9-1.1): (1.0-1.3).
  • the lithium source is selected from n-butyl lithium, lithium hydroxide, lithium nitrate, lithium oxalate, At least one of lithium carbonate, lithium acetate and lithium oxide.
  • the preparation process of the modified ferromanganese phosphate includes: reacting the ferromanganese phosphate with a soluble salt solution containing element A in the presence of a complexing agent, and controlling the pH value to be 9-14 during the reaction.
  • the complexing agent is an aqueous ammonia solution, and the mass fraction of ammonia in the aqueous ammonia solution is 0.03%-0.15%.
  • the amount of ammonia solution corresponding to 1 kg of ferromanganese phosphate is 3 L-15 L.
  • the mass ratio of the content of element A in the soluble salt solution to ferromanganese phosphate is 0.0001-0.10:1.
  • the mass ratio of the content of element A in the soluble salt solution to ferromanganese phosphate is 0.01-0.05:1.
  • the concentration of the soluble salt solution is 0.002M-0.03M, and the volume of the soluble salt solution corresponding to 1kg of manganese iron phosphate is 0.2L-3L.
  • the soluble salt solution is selected from at least one of sulfate, chloride and nitrate.
  • the reaction temperature is controlled to be 90° C.-130° C., and the reaction time is 3 h-30 h.
  • the preparation process of ferromanganese phosphate includes: mixing and reacting iron salt, manganese salt and phosphate, controlling the molar ratio of manganese, iron and phosphorus in the raw materials to be (0.10-0.80): (0.20-0.90): (1.0-1.3), and controlling the median particle size of the obtained ferromanganese phosphate to be 0.12 ⁇ m-10 ⁇ m.
  • the reaction temperature is controlled to be 500° C.-900° C., and the reaction time is 8 h-36 h.
  • the solution provided by the present disclosure also includes a lithium iron manganese phosphate positive electrode plate, including a positive electrode collector, on which a positive electrode active coating is attached, and the positive electrode active coating contains the lithium iron manganese phosphate positive electrode material in any of the above-mentioned embodiments or the lithium iron manganese phosphate positive electrode material prepared by the preparation method in any of the above-mentioned embodiments.
  • the positive electrode active coating further contains a binder, a regulator and a conductive agent, and the mass ratio of the lithium manganese iron phosphate positive electrode material, the binder, the regulator and the conductive agent is (80-98.7): (0.2-8): (0.1-5): (1-7).
  • the lithium manganese iron phosphate positive electrode material, the binder, the regulator and the conductive agent The mass ratio is (93-97):(0.5-2):(0.5 ⁇ 2):(2-3).
  • the regulator is at least one of sodium polyacrylate, polyrotaxane, polyacrylamide and polyethyleneimine.
  • the conductive agent is selected from at least one of conductive carbon black, acetylene black, graphite and graphene.
  • the binder is selected from at least one of guar gum, sodium alginate, sodium carboxymethyl cellulose, gum arabic, carrageenan, styrene-butadiene rubber and polyvinylidene fluoride.
  • the positive electrode current collector is aluminum foil.
  • the solution provided by the present disclosure also includes a method for preparing a lithium iron manganese phosphate positive electrode sheet in any of the above-mentioned embodiments, comprising: forming a positive electrode active coating on the positive electrode collector, and making the positive electrode active coating contain lithium iron manganese phosphate positive electrode material.
  • the lithium manganese iron phosphate positive electrode material, the binder, the regulator and the conductive agent are mixed, and then mixed with a solvent to obtain a positive electrode slurry, and the positive electrode slurry is coated on at least one side of the positive electrode current collector, and then dried;
  • the viscosity of the positive electrode slurry is 3000mPa.s-8500mPa.s.
  • the solution provided by the present disclosure also includes a lithium battery, including the lithium iron manganese phosphate positive electrode sheet in any of the above embodiments or the lithium iron manganese phosphate positive electrode sheet prepared by the preparation method in any of the above embodiments.
  • the solution provided by the present disclosure also includes an electrical device, comprising a lithium battery in any of the above embodiments.
  • the introduced superionic conductors have stronger conductivity, thereby improving the conductivity of the particles and the conductivity of the positive electrode material; at the same time, the transmission of ions between the positive electrode particles is promoted, and the cycle performance of the positive electrode material is improved.
  • the presence of superionic conductors and carbon layers can minimize the direct contact between the electrolyte and iron and manganese, thereby improving the side reactions between the surface of the positive electrode particles and the electrolyte, stabilizing the internal structure of the lithium iron manganese phosphate positive electrode particles, and improving the electrochemical performance of the material.
  • FIG1 is a flow chart of the preparation process of the lithium iron manganese phosphate positive electrode sheet provided by the present disclosure
  • FIG2 is an XRD diagram of the lithium iron manganese phosphate positive electrode material of Example 1;
  • FIG. 3 is a SEM image of the lithium manganese iron phosphate positive electrode material of Example 1.
  • any values of the ranges disclosed in this disclosure are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values.
  • the endpoint values of each range, the endpoint values of each range and the individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.
  • the disclosed embodiment provides a method for preparing a lithium iron manganese phosphate positive electrode material.
  • a superionic conductor on a lithium iron manganese phosphate substrate, the material can have high conductivity and good electrochemical performance under high voltage.
  • a carbon layer is introduced on the surface of the lithium iron manganese phosphate substrate. The presence of the superionic conductor and the carbon layer can reduce the direct contact between the electrolyte and iron and manganese to a greater extent, thereby improving the side reaction between the surface of the positive electrode particles and the electrolyte, stabilizing the internal structure of the lithium iron manganese phosphate positive electrode particles, and thus improving the electrochemical performance of the material.
  • the manganese ferrophosphate to be modified can be a material doped with element A.
  • the element ratio can be controlled as required.
  • the preparation process of the modified ferromanganese phosphate includes: reacting ferromanganese phosphate with a soluble salt solution containing element A in the presence of a complexing agent, and controlling the pH value to be 9-14 during the reaction to introduce the doping element A into the ferromanganese phosphate.
  • a sodium hydroxide solution can be used to adjust the reaction pH value.
  • the complexing agent can be an ammonia solution, the mass fraction of ammonia in the ammonia solution is 0.03%-0.15%, and the amount of ammonia solution corresponding to 1kg of ferromanganese phosphate is 3L-15L.
  • the concentration and amount of the ammonia solution By controlling the concentration and amount of the ammonia solution, a uniform ferromanganese phosphate to be modified can be obtained.
  • the mass fraction of ammonia in the ammonia solution can be 0.03%, 0.05%, 0.08%, 0.10%, 0.12%, 0.15%, etc.
  • the amount of ammonia solution corresponding to 1kg of ferromanganese phosphate is 3L-15L. It can be 3L, 5L, 8L, 10L, 12L, 15L, etc.
  • the mass ratio of the content of element A in the soluble salt solution to ferromanganese phosphate is 0.0001-0.10:1 (such as 0.0001:1, 0.0005:1, 0.001:1, 0.005:1, 0.010:1, 0.015:1, 0.10:1, etc.), preferably 0.01-0.05:1.
  • the concentration of the soluble salt solution is 0.002M-0.03M
  • the volume of the soluble salt solution corresponding to 1kg ferromanganese phosphate is 0.2L-3L, respectively.
  • the concentration and dosage of the soluble salt solution are further controlled to control the doping amount of element A.
  • the soluble salt solution is selected from at least one of sulfate, chloride and nitrate, and can be any one or more of the above.
  • the concentration of element A in the soluble salt solution can be 0.002M, 0.005M, 0.010M, 0.020M, 0.030M, etc.
  • the volume of the soluble salt solution corresponding to 1kg of ferromanganese phosphate can be 0.2L, 0.5L, 1.0L, 2.0L, 3.0L, etc.
  • the reaction temperature is controlled to be 90°C-130°C, and the reaction time is 3h-30h, so that the reaction is fully carried out and the utilization rate of raw materials is improved.
  • the reaction temperature can be 90°C, 100°C, 110°C, 120°C, 130°C, etc.
  • the reaction time can be 3h, 5h, 10h, 15h, 20h, 25h, 30h, etc. After the reaction is completed, only cooling, washing, and filter pressing are performed.
  • the ferromanganese phosphate used in the process of preparing the ferromanganese phosphate to be modified can be a commercially available product or can be independently synthesized.
  • the preparation process of ferromanganese phosphate includes: mixing and reacting iron salt, manganese salt and phosphate, controlling the molar ratio of manganese, iron and phosphorus in the raw materials to be (0.10-0.80): (0.20-0.90): (1.0-1.3), and controlling the median particle size of the obtained ferromanganese phosphate to be 0.12 ⁇ m-10 ⁇ m.
  • the reaction is carried out in an inert environment (such as a nitrogen atmosphere), the reaction temperature is controlled to be 500°C-900°C, and the reaction time is 8h-36h.
  • the median particle size of the prepared ferromanganese phosphate is within the above range.
  • the iron salt may be, but not limited to, iron phosphate
  • the manganese salt may be, but not limited to, manganese sulfate
  • the phosphate may be, but not limited to, ammonium phosphate.
  • the reaction temperature may be 500°C, 600°C, 700°C, 800°C, 900°C, etc.
  • the reaction time may be 8h, 10h, 20h, 30h, 36h, etc.
  • the manganese iron phosphate to be modified, the gel material, the superionic conductor and the lithium source are mixed to obtain a mixed material for use.
  • the mass ratio of the modified ferromanganese phosphate, the gel material and the superionic conductor is 100:(2-15):(0.4-8), and the thickness of the carbon layer and the amount of the superionic conductor introduced are controlled by controlling the amount of the gel material and the superionic conductor to further improve the electrochemical performance of the positive electrode material.
  • the mass ratio of the modified ferromanganese phosphate, the gel material and the superionic conductor can be 100:2:0.4, 100:5:2.0, 100:8:4.0, 100:10:5.0, 100:12:6.0, 100:15:8.0, etc.
  • the superionic conductor is selected from at least one of titanium zirconium phosphate, titanium yttrium phosphate, vanadium zirconium phosphate and vanadium yttrium phosphate, and can be any one or more of the above, preferably at least one of titanium zirconium phosphate and titanium yttrium phosphate.
  • the gel material is corn starch gel.
  • the lithium source is selected from at least one of n-butyl lithium, lithium hydroxide, lithium nitrate, lithium oxalate, lithium carbonate, lithium acetate and lithium oxide, and can be any one or more of the above.
  • the preparation process of the mixed material includes: mixing the manganese iron phosphate to be modified, the gel material and the superionic conductor under heating conditions, and then mixing with the lithium source to improve the uniformity of the mixing to form a gel coating.
  • the heating temperature is controlled to be 50°C-70°C, such as 50°C, 60°C, 70°C, etc., and the mixing process is carried out under stirring conditions.
  • the molar ratio of the total amount of metal elements in the modified ferromanganese phosphate to the lithium element in the lithium source is (0.9-1.1): (1.0-1.3), such as 0.9:1.0, 1.0:1.1, 1.1:1.3, etc.
  • the mixed material is heated and dehydrated, and then sintered. During the heating and dehydration process, a porous structure can be formed, part of the superionic conductor enters between the positive electrode particles, and part of the superionic conductor forms a double layer with C on the surface of the positive electrode material during the sintering stage.
  • the heating temperature is controlled to be 110°C-200°C and the heating time is 2h-4h during the heating dehydration process.
  • the heating dehydration can be carried out under the condition of air ventilation.
  • the mixture is cooled to room temperature and ball milled, and then sintered.
  • the water molecules in the mixture are slowly removed under low temperature conditions.
  • the precipitation path of the water molecules in the gel coating layer is used to form channels, thereby forming holes. There will be agglomeration after heating and dehydration, and the particles are evenly dispersed through ball milling.
  • the sintering temperature is controlled to be 500°C-1100°C
  • the sintering time is 8h-30h
  • the sintering process can be carried out under an inert atmosphere.
  • the prepared lithium manganese iron phosphate positive electrode material has a median particle size of 0.4 ⁇ m-5.0 ⁇ m and a specific surface area of 5m2 /g- 13m2 /g.
  • the inert atmosphere may be neon, argon, nitrogen, etc., or may be carried out in other oxygen-free environments.
  • the sintering temperature may be 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C, etc.
  • the sintering time may be 8h, 10h, 15h, 20h, 25h, 30h, etc.
  • the present disclosure also provides a lithium iron manganese phosphate positive electrode material, including a lithium iron manganese phosphate substrate, a carbon layer coated on the lithium iron manganese phosphate substrate, and the lithium iron manganese phosphate positive electrode material contains a superionic conductor, and the superionic conductor is selected from at least one of titanium zirconium phosphate, titanium yttrium phosphate, vanadium zirconium phosphate and vanadium yttrium phosphate.
  • the introduced superionic conductors By introducing superionic conductors into the lithium manganese iron phosphate matrix and optimizing the selection of the types of superionic conductors, the introduced superionic conductors have stronger conductivity, thereby improving the conductivity of the particles and increasing the conductivity of the positive electrode material; at the same time, it promotes the transmission of ions between the positive electrode particles and improves the cycle performance of the positive electrode material.
  • the surface of the lithium iron manganese phosphate substrate is also coated with a carbon layer, part of the superionic conductor and the carbon layer are co-coated on the surface of the lithium iron manganese phosphate substrate, and part of the superionic conductor is distributed inside the lithium iron manganese phosphate substrate.
  • the presence of the superionic conductor and the carbon layer can minimize the direct contact between the electrolyte and iron and manganese, thereby improving the side reaction between the surface of the positive electrode particles and the electrolyte, stabilizing the internal structure of the lithium iron manganese phosphate positive electrode particles, and thus improving the electrochemical performance of the material.
  • the mass fraction of the superionic conductor in the lithium iron manganese phosphate positive electrode material is 0.25%-6.0% (such as 0.25%, 0.50%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 6.0%, etc.).
  • the carbon content in the lithium iron manganese phosphate positive electrode material is 1%-3% (such as 1%, 2%, 3%, etc.).
  • the mass fraction of element A is 0.005%-6%, and the electrochemical performance of the positive electrode material is further improved by controlling the doping amount of element A.
  • the mass fraction of element A can be 0.005%, 0.01%, 0.1%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 6.0%, etc.
  • the disclosed embodiment also provides a lithium iron manganese phosphate positive electrode plate, including a positive electrode collector, on which a positive electrode active coating is attached, and the positive electrode active coating contains the above-mentioned lithium iron manganese phosphate positive electrode material.
  • the improvement of the lithium iron manganese phosphate positive electrode material can further improve the electrochemical performance of the lithium iron manganese phosphate positive electrode plate.
  • the positive electrode active coating further contains a binder, a regulator and a conductive agent, and the mass ratio of the lithium manganese iron phosphate positive electrode material, the binder, the regulator and the conductive agent is (80-98.7): (0.2-8): (0.1-5): (1-7), preferably (93-97): (0.5-2): (0.5-2): (2-3).
  • the regulator is at least one of sodium polyacrylate, polyrotaxane, polyacrylamide and polyethyleneimine, and can be any one or more of the above.
  • the regulator has very high bonding properties and good mechanical properties, especially good flexibility, and will not crack during the cutting of the electrode piece; it is not easy to swell excessively in the electrolyte, and basically no side reactions occur when in contact with the electrolyte; it can tightly adhere the positive electrode active material to the current collector, and during the cycle process, it can stabilize the electrode structure and inhibit the material from falling off the electrode piece, thereby improving the cycle performance of the battery.
  • the conductive agent is selected from at least one of conductive carbon black, acetylene black, graphite and graphene, and may be any one or more of the above.
  • the binder is selected from at least one of guar gum, sodium alginate, sodium carboxymethyl cellulose, gum arabic, carrageenan, styrene-butadiene rubber and polyvinylidene fluoride, and may be any one or more of the above.
  • the positive electrode current collector may be, but is not limited to, aluminum foil.
  • the present disclosure also provides a method for preparing a lithium manganese iron phosphate positive electrode sheet, comprising: A positive electrode active coating is formed on the positive electrode, and the positive electrode active coating contains the lithium iron manganese phosphate positive electrode material in the above embodiment.
  • the preparation method is not limited and can refer to the prior art, such as using the lithium iron manganese phosphate positive electrode material to prepare a slurry, coating it on the positive electrode current collector, and then drying it.
  • the lithium manganese iron phosphate positive electrode material, the binder, the regulator and the conductive agent are mixed, and then mixed with the solvent to obtain a positive electrode slurry, and the positive electrode slurry is applied to at least one side of the positive electrode collector, and then dried, cold pressed and sliced to obtain a lithium manganese iron phosphate positive electrode sheet.
  • the viscosity of the positive electrode slurry is 3000mPa.s-8500mPa.s.
  • the solvent can be, but is not limited to, NMP, which is used to adjust the viscosity within the above range.
  • the viscosity of the positive electrode slurry can be 3000 mPa.s, 4000 mPa.s, 5000 mPa.s, 6000 mPa.s, 7000 mPa.s, 8000 mPa.s, 8500 mPa.s, etc.
  • the disclosed embodiment also provides a lithium battery, including the above-mentioned lithium iron manganese phosphate positive electrode plate, and may also include a negative electrode plate, an electrolyte, a separator, etc. to form a complete lithium battery structure.
  • the disclosed embodiments further provide an electrical device, including the lithium battery described above, and may also include electrical equipment, the specific types of which are not limited.
  • This embodiment provides a method for preparing a lithium manganese iron phosphate positive electrode sheet, comprising the following steps:
  • Ferromanganese phosphate was placed in a closed reactor, and an ammonia solution with an ammonia mass fraction of 0.08 wt% and a 0.017 M nickel sulfate solution (ferromanganese phosphate, ammonia solution and nickel sulfate solution were mixed in a ratio of 1 kg:5.5 L:0.8 L) were injected, and heated at 95°C for 12 hours, sodium hydroxide was added to adjust the pH to 11.3, stirred, cooled, washed and filtered, and doped ferromanganese phosphate B (Mn 0.427 Ni 0.003 Fe 0.57 PO 4 ) was obtained.
  • an ammonia solution with an ammonia mass fraction of 0.08 wt% and a 0.017 M nickel sulfate solution (ferromanganese phosphate, ammonia solution and nickel sulfate solution were mixed in a ratio of 1 kg:5.5 L:0.8 L) were injected, and heated at 95°C for 12 hours, sodium
  • the mixture C is sent to a heating furnace, heated at 110° C. for 4 h under air flow for dehydration, the gel coating layer is porous, cooled to room temperature, and then sent to 740° C. for heating in a nitrogen environment for 15 h, annealed to room temperature, dried, ball-milled, and sieved to obtain a coated lithium manganese iron phosphate positive electrode material;
  • the coated lithium manganese iron phosphate positive electrode material, polyvinylidene fluoride, polyacrylamide, and conductive carbon black are mixed and stirred in a mass ratio of 96:0.5:0.5:3, and then the solvent NMP is added to adjust the viscosity to 5000-5340mPa.s, and a single layer is coated on an aluminum foil current collector, dried, rolled, and sliced to obtain a lithium manganese iron phosphate positive electrode sheet.
  • This embodiment provides a method for preparing a lithium manganese iron phosphate positive electrode sheet, comprising the following steps:
  • Ferromanganese phosphate was placed in a closed reactor, and an ammonia solution with an ammonia mass fraction of 0.08wt% and a 0.017M nickel sulfate solution (ferromanganese phosphate, ammonia solution and nickel sulfate solution were mixed in a ratio of 1kg:5.5L:0.8L) were injected, and heated at 95°C for 12 hours, sodium hydroxide was added to adjust the pH to 10.3, stirred, cooled, washed and filtered, and doped ferromanganese phosphate B (Mn 0.297 Ni 0.003 Fe 0.70 PO 4 ) was obtained.
  • an ammonia solution with an ammonia mass fraction of 0.08wt% and a 0.017M nickel sulfate solution (ferromanganese phosphate, ammonia solution and nickel sulfate solution were mixed in a ratio of 1kg:5.5L:0.8L) were injected, and heated at 95°C for 12 hours, sodium hydrox
  • the mixture C is sent to a heating furnace and heated at 115° C. for 3.5 hours under air for dehydration to form pores in the gel coating layer. After cooling to room temperature, it is sent to 740° C. for heating in a nitrogen environment for 15 hours, annealed to room temperature, dried, ball-milled, and sieved to obtain a coated lithium manganese iron phosphate positive electrode material.
  • the coated lithium manganese iron phosphate positive electrode material, polyvinylidene fluoride, polyacrylamide, and conductive carbon black are mixed and stirred in a mass ratio of 96:0.5:0.5:3, and a solvent NMP is added to adjust the viscosity to 5000-5340 mPa.s.
  • a single layer is coated on an aluminum foil current collector, and the mixture is dried, rolled, and sliced to obtain a lithium manganese iron phosphate positive electrode sheet.
  • This embodiment provides a method for preparing a lithium manganese iron phosphate positive electrode sheet, comprising the following steps:
  • Ferromanganese phosphate was placed in a closed reactor, and an ammonia solution with an ammonia mass fraction of 0.08wt% and a 0.017M nickel sulfate solution (ferromanganese phosphate, ammonia solution and nickel sulfate solution were mixed in a ratio of 1kg:5.5L:0.8L) were injected, and heated at 95°C for 12 hours, sodium hydroxide was added to adjust the pH to 11.3, stirred, cooled, washed and filtered, and doped ferromanganese phosphate B (Mn 0.447 Ni 0.003 Fe 0.55 PO 4 ) was obtained.
  • an ammonia solution with an ammonia mass fraction of 0.08wt% and a 0.017M nickel sulfate solution (ferromanganese phosphate, ammonia solution and nickel sulfate solution were mixed in a ratio of 1kg:5.5L:0.8L) were injected, and heated at 95°C for 12 hours, sodium hydrox
  • the mixture C is sent to a heating furnace, heated at 110° C. in air for 4 h for dehydration, and the gel coating layer is porous. After cooling to room temperature, it is sent to 740° C. in a nitrogen environment for heating for 15 h, annealed to room temperature, dried, ball-milled, and sieved to obtain a coated lithium manganese iron phosphate positive electrode material.
  • the coated lithium manganese iron phosphate positive electrode material, polyvinylidene fluoride, sodium polyacrylate, and conductive carbon black are mixed and stirred in a mass ratio of 95:1:1:3, and a solvent NMP is added to adjust the viscosity to 6000-6300 mPa.s.
  • a single layer is coated on an aluminum foil current collector, and the mixture is dried, rolled, and sliced to obtain a lithium manganese iron phosphate positive electrode sheet.
  • This embodiment provides a method for preparing a lithium manganese iron phosphate positive electrode sheet, comprising the following steps:
  • Ferromanganese phosphate was placed in a closed reactor, and an ammonia solution with an ammonia mass fraction of 0.08wt% and a 0.017M nickel sulfate solution (ferromanganese phosphate, ammonia solution and nickel sulfate solution were mixed in a ratio of 1kg:5.5L:0.8L) were injected, and heated at 95°C for 12 hours, sodium hydroxide was added to adjust the pH to 12, stirred, cooled, washed and filtered to obtain doped ferromanganese phosphate B (Mn 0.427 Ni 0.003 Fe 0.57 PO 4 ).
  • the mixture C is sent to a heating furnace, heated at 120° C. in air for 3 h for dehydration, and the gel coating layer is porous. After cooling to room temperature, it is sent to 740° C. in a nitrogen environment for heating for 15 h, annealed to room temperature, dried, ball-milled, and sieved to obtain a coated lithium manganese iron phosphate positive electrode material.
  • the coated lithium manganese iron phosphate positive electrode material, polyvinylidene fluoride, sodium polyacrylate, and conductive carbon black are mixed and stirred in a mass ratio of 96:0.5:0.8:2.7, and a solvent NMP is added to adjust the viscosity to 5500-6000 mPa.s.
  • a single layer is coated on an aluminum foil current collector, and the mixture is dried, rolled, and sliced to obtain a lithium manganese iron phosphate positive electrode sheet.
  • This embodiment provides a method for preparing a lithium manganese iron phosphate positive electrode sheet, comprising the following steps:
  • the mixture C is sent to a heating furnace and heated at 130° C. for 2.5 h in air for dehydration to form pores in the gel coating layer. After cooling to room temperature, the mixture is sent to 740° C. for heating in a nitrogen environment for 15 h, annealed to room temperature, dried, ball-milled, and sieved to obtain a coated lithium manganese iron phosphate positive electrode material.
  • the coated lithium manganese iron phosphate positive electrode material, polyvinylidene fluoride, polyacrylamide, and conductive carbon black are mixed and stirred in a mass ratio of 96:0.5:0.5:3, and a solvent NMP is added to adjust the viscosity to 5000-5340 mPa.s.
  • a single layer is coated on an aluminum foil current collector, and the mixture is dried, rolled, and sliced to obtain a lithium manganese iron phosphate positive electrode sheet.
  • This embodiment provides a method for preparing a lithium manganese iron phosphate positive electrode sheet, comprising the following steps:
  • Ferromanganese phosphate was placed in a closed reactor, and an ammonia solution with an ammonia mass fraction of 0.08wt% and a cobalt sulfate solution of 0.017M (ferromanganese phosphate, ammonia solution and cobalt sulfate solution were mixed in a ratio of 1kg:5.5L:0.8L) were injected, and heated at 95°C for 12 hours, sodium hydroxide was added to adjust the pH to 11.0, stirred, cooled, washed and filtered, and doped ferromanganese phosphate B (Mn 0.197 Co 0.003 Fe 0.80 PO 4 ) was obtained.
  • the mixture C is sent to a heating furnace, heated at 120° C. for 4 h in air for dehydration, and the gel coating layer is porous. After cooling to room temperature, it is sent to 740° C. for heating for 15 h in a nitrogen environment, annealed to room temperature, dried, ball-milled, and sieved to obtain a coated lithium manganese iron phosphate positive electrode material.
  • the coated lithium manganese iron phosphate positive electrode material, polyvinylidene fluoride, polyacrylamide, and conductive carbon black are mixed and stirred in a mass ratio of 96:0.5:0.5:3, and a solvent NMP is added to adjust the viscosity to 5000-5340 mPa.s.
  • a single layer is coated on an aluminum foil current collector, and the mixture is dried, rolled, and sliced to obtain a lithium manganese iron phosphate positive electrode sheet.
  • This embodiment provides a method for preparing a lithium manganese iron phosphate positive electrode sheet, which differs from embodiment 6 mainly in that In: No polyacrylamide is introduced during the preparation process. The specific steps are as follows:
  • Ferromanganese phosphate was placed in a closed reactor, and an ammonia solution with an ammonia mass fraction of 0.08wt% and a cobalt sulfate solution of 0.017M (ferromanganese phosphate, ammonia solution and cobalt sulfate solution were mixed in a ratio of 1kg:5.5L:0.8L) were injected, and heated at 95°C for 12 hours, sodium hydroxide was added to adjust the pH to 11.0, stirred, cooled, washed and filtered, and doped ferromanganese phosphate B (Mn 0.197 Co 0.003 Fe 0.80 PO 4 ) was obtained.
  • the mixture C is sent to a heating furnace, heated at 120° C. for 4 h in air for dehydration, and the gel coating layer is porous. After cooling to room temperature, it is sent to 740° C. for heating for 15 h in a nitrogen environment, annealed to room temperature, dried, ball-milled, and sieved to obtain a coated lithium manganese iron phosphate positive electrode material.
  • the coated lithium manganese iron phosphate positive electrode material, polyvinylidene fluoride, and conductive carbon black are mixed and stirred in a mass ratio of 96:1:3, and a solvent NMP is added to adjust the viscosity to 5000-5340 mPa.s.
  • a single layer is coated on an aluminum foil current collector, and the mixture is dried, rolled, and sliced to obtain a lithium manganese iron phosphate positive electrode sheet.
  • This comparative example provides a method for preparing a lithium manganese iron phosphate positive electrode sheet.
  • the difference between this comparative example and Example 1 is that no corn starch gel is added during the preparation process.
  • the specific steps are as follows:
  • Ferromanganese phosphate was placed in a closed reactor, and an ammonia solution with an ammonia mass fraction of 0.08wt% and a 0.017M nickel sulfate solution (ferromanganese phosphate, ammonia solution and nickel sulfate solution were mixed in a ratio of 1kg:5.5L:0.8L) were injected, and heated at 95°C for 12 hours.
  • Sodium hydroxide was added to adjust the pH to 11.3, stirred, cooled, washed and filtered to obtain doped ferromanganese phosphate B (Mn 0.427 Ni 0.003 Fe 0.57 PO 4 )
  • the mixture C was sent to a heating furnace, heated at 740° C. in a nitrogen environment for 15 h, annealed to room temperature, dried, ball-milled, and sieved to obtain a coated lithium manganese iron phosphate positive electrode material.
  • the coated lithium manganese iron phosphate positive electrode material, polyvinylidene fluoride, polyacrylamide, and conductive carbon black are mixed and stirred in a mass ratio of 96:0.5:0.5:3, and a solvent NMP is added to adjust the viscosity to 5000-5340 mPa.s.
  • a single layer is coated on an aluminum foil current collector, and the mixture is dried, rolled, and sliced to obtain a lithium manganese iron phosphate positive electrode sheet.
  • This comparative example provides a method for preparing a lithium manganese iron phosphate positive electrode sheet, which is different from Example 1 mainly in that titanium zirconium phosphate is not added during the preparation process.
  • the specific steps are as follows:
  • Ferromanganese phosphate was placed in a closed reactor, and an ammonia solution with an ammonia mass fraction of 0.08wt% and a 0.017M nickel sulfate solution (ferromanganese phosphate, ammonia solution and nickel sulfate solution were mixed in a ratio of 1kg:5.5L:0.8L) were injected, and heated at 95°C for 12 hours.
  • Sodium hydroxide was added to adjust the pH to 11.3, stirred, cooled, washed and filtered to obtain doped ferromanganese phosphate B (Mn 0.427 Ni 0.003 Fe 0.57 PO 4 )
  • the doped manganese ferrophosphate B and corn starch gel are mixed and stirred in a mass ratio of 100:2 to form a gel coating.
  • the heating temperature is controlled to be 65°C.
  • lithium carbonate is added (the metal in the doped manganese ferrophosphate B and the lithium in the lithium carbonate are mixed in a molar ratio of 1.02:1.15) and stirred to obtain a mixture C.
  • the mixture C is sent to a heating furnace, heated at 110° C. for 4 h in air for dehydration, and the gel coating layer is porous. After cooling to room temperature, it is sent to 740° C. for heating for 15 h in a nitrogen environment, annealed to room temperature, dried, ball-milled, washed, dried, sieved, and demagnetized to obtain a coated lithium manganese iron phosphate positive electrode material.
  • the coated lithium manganese iron phosphate positive electrode material, polyvinylidene fluoride, polyacrylamide, and conductive carbon black are mixed and stirred in a mass ratio of 96:0.5:0.5:3, and a solvent NMP is added to adjust the viscosity to 5000-5340 mPa.s.
  • a single layer is coated on an aluminum foil current collector, and the mixture is dried, rolled, and sliced to obtain a lithium manganese iron phosphate positive electrode sheet.
  • This comparative example provides a method for preparing a lithium manganese iron phosphate positive electrode sheet, which is different from Example 5 mainly in that no yttrium vanadium phosphate is added during the preparation process.
  • the specific steps are as follows:
  • Ferric phosphate, manganese sulfate and ammonium phosphate were mixed in a molar ratio of manganese, iron and phosphorus of 0.20:0.80:1.2, and heated at 700°C in a nitrogen environment for 16 hours to obtain ferromanganese phosphate with a median particle size of 5 ⁇ m for standby use.
  • Ferromanganese phosphate was placed in a closed reactor, and an ammonia solution with an ammonia mass fraction of 0.08wt% and a 0.017M cobalt sulfate solution (ferromanganese phosphate, ammonia solution and cobalt sulfate solution were mixed in a ratio of 1kg:5.5L:0.8L) were injected, and heated at 95°C for 12 hours, sodium hydroxide was added to adjust the pH to 11.0, stirred, cooled, washed and filtered to obtain doped ferromanganese phosphate B (Mn 0.197 Co 0.003 Fe 0.80 PO 4 ).
  • the mixture C was sent to a heating furnace, heated at 130° C. in air for 2.5 h for dehydration, cooled to room temperature, and then sent to 740° C. in a nitrogen environment for heating for 15 h.
  • the mixture was annealed to room temperature, dried, ball-milled, and sieved to obtain a coated lithium manganese iron phosphate positive electrode material.
  • the coated lithium manganese iron phosphate positive electrode material, polyvinylidene fluoride, polyacrylamide, and conductive carbon black are mixed and stirred in a mass ratio of 96:0.5:0.5:3, and a solvent NMP is added to adjust the viscosity to 5000-5340 mPa.s.
  • a single layer is coated on an aluminum foil current collector, and the mixture is dried, rolled, and sliced to obtain a lithium manganese iron phosphate positive electrode sheet.
  • This comparative example provides a method for preparing a lithium manganese iron phosphate positive electrode sheet, which differs from Example 6 mainly in that zirconium titanium phosphate is replaced with an equal amount of potassium titanium phosphate.
  • the specific steps are as follows:
  • Ferromanganese phosphate was placed in a closed reactor, and an ammonia solution with an ammonia mass fraction of 0.08wt% and a cobalt sulfate solution of 0.017M (ferromanganese phosphate, ammonia solution and cobalt sulfate solution were mixed in a ratio of 1kg:5.5L:0.8L) were injected, and heated at 95°C for 12 hours, sodium hydroxide was added to adjust the pH to 11.0, stirred, cooled, washed and filtered, and doped ferromanganese phosphate B (Mn 0.197 Co 0.003 Fe 0.80 PO 4 ) was obtained.
  • the mixture C is sent to a heating furnace, heated at 120° C. for 4 h in air for dehydration, and the gel coating layer is porous. After cooling to room temperature, it is sent to 740° C. for heating for 15 h in a nitrogen environment, annealed to room temperature, dried, ball-milled, and sieved to obtain a coated lithium manganese iron phosphate positive electrode material.
  • the coated lithium manganese iron phosphate positive electrode material, polyvinylidene fluoride, polyacrylamide, and conductive carbon black are mixed and stirred in a mass ratio of 96:0.5:0.5:3, and a solvent NMP is added to adjust the viscosity to 5000-5340 mPa.s.
  • a single layer is coated on an aluminum foil current collector, and the mixture is dried, rolled, and sliced to obtain a lithium manganese iron phosphate positive electrode sheet.
  • the XRD pattern of the lithium iron manganese phosphate positive electrode material prepared in Test Example 1 is shown in Figure 2.
  • the SEM pattern of the lithium iron manganese phosphate positive electrode material prepared in Test Example 1 is shown in Figure 3.
  • the ferromanganese phosphate prepared by the present invention has a better crystal form and no impurity phase is generated.
  • the particle size of the lithium iron phosphate prepared by the present invention is small, the grains are stacked together, and the conductive network Covering shortens the lithium ion transmission path and further increases the migration rate of lithium ions.
  • Test method (1) Use a specific surface area tester to measure the specific surface area SSa value of the positive electrode material, and a laser particle size analyzer to measure the median particle size D50 of the positive electrode material. (2) Use a powder conductivity tester to test the conductivity of the positive electrode materials of the embodiment and the comparative example, and use a tensile testing machine to test the electrode peeling strength. (3) The positive electrode sheets prepared in the embodiment and the comparative example are placed in a vacuum oven for drying (80°C, 3h); and punched into discs with a diameter of 12mm.
  • the positive electrode uses a dry electrode sheet
  • the positive electrode uses a lithium sheet as the counter electrode
  • the diaphragm is a PP and PE composite diaphragm
  • the electrolyte 1M LiPF6 EC, DMC, DEC (volume ratio of 1:1:1).
  • the prepared half-cell is tested using a CT2001A battery detection system, and the cut-off voltage is 2.0-4.3V. First, charge at a constant current of 0.1C to 4.3V, then charge at a constant voltage of 4.3V to a current ⁇ 0.05C, and perform a discharge performance test at 0.1C.
  • Example 7 the specific surface area and particle size of the lithium iron manganese phosphate positive electrode materials in Examples 1-7 and Comparative Examples 1-4 are not much different, but there are certain differences in their conductivity and peel strength.
  • the conductivity of Examples 1-7 is significantly higher than that of Comparative Examples 1-3.
  • Example 7 no regulator was added when making the positive electrode sheet, resulting in a lower peel strength of the electrode sheet.
  • the reason for the lower conductivity of Comparative Example 1 is that no gel was added, so that the surface of the material is not coated with a carbon layer, and thus the conductivity is not greatly improved.
  • the reason for the lower conductivity of Comparative Examples 2 and 3 is that no superionic conductor was added, resulting in lower conductivity.
  • the reason for the lower conductivity of Comparative Example 4 is that the coated superionic conductor is outside the preferred range of the present invention, and the conductivity is not improved much. Not as good as the embodiments.
  • the first discharge specific capacity of the half-cell prepared in Examples 1-6 and Comparative Examples 1-4 is between 155.7 and 160.3 mAh/g and 145.4 and 156.2 mAh/g, respectively.
  • the first coulombic efficiency and 300-cycle capacity retention rate of Examples 1-7 are better than those of Comparative Examples 1-4; in Example 7, the regulator is added during the preparation of the pole piece, resulting in low peeling strength, and the pole piece may fall off during the cycle, and then after 300 cycles, the capacity retention rate is relatively low.
  • the reason for the low first discharge specific capacity of Comparative Example 1 is that corn starch gel is not added during the preparation process, and C coating cannot be formed, which ultimately leads to low conductivity.
  • Comparative Examples 2 and 3 The discharge specific capacity of Comparative Examples 2 and 3 is low, and the reason is that no superionic conductor is added during the preparation process, resulting in low conductivity, which ultimately affects the discharge specific capacity.
  • the reason for the low capacity and cycle retention rate of Comparative Example 4 is that the coated superionic conductor is outside the preferred range of the present invention, and its ability to improve conductivity is limited. Relatively speaking, the electrochemical performance of the embodiment is better.
  • the present disclosure introduces a superionic conductor into the lithium iron manganese phosphate substrate, and optimizes the type of superionic conductor so that the introduced superionic conductor has a stronger conductivity, thereby improving the conductivity and cycle performance of the particles.
  • the regulator introduced can prevent the pole piece from swelling too much in the electrolyte, and can tightly adhere the positive electrode active material to the current collector.
  • the electrode structure can be stabilized, and the material can be inhibited from falling off the pole piece, thereby improving the cycle performance of the battery.
  • the preparation method provided by the present disclosure The operation is convenient and the industrial applicability is very good.

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Abstract

本公开属于锂电池技术领域，具体涉及一种磷酸锰铁锂正极材料、极片及其制备方法和应用。通过在磷酸锰铁锂基材中引入超离子导电体，配合对超离子导电体的种类进行选择优化，超离子导电体以及碳层的存在可以更大限度地降低电解液与铁、锰的直接接触，从而改善了正极颗粒表面与电解液副反应，能够稳定磷酸锰铁锂正极颗粒内部结构，进而改善材料的电化学性能。通过在极片制备过程中，引入的调节剂，可以使极片在电解液中不容易发生过多溶胀，可以紧密将正极活性材料与集流体粘连，在循环过程中，能够稳定电极结构，抑制材料从极片脱落，从而提升电池的循环性能。

Description

一种磷酸锰铁锂正极材料、极片及其制备方法和应用 技术领域
本公开属于锂电池技术领域，具体而言，涉及一种磷酸锰铁锂正极材料、极片及其制备方法和应用。
背景技术
目前锂离子电池作为储能材料相比传统电池具有电压高、比容量大、循环寿命长和安全性能好的优点，被广泛应用于便携式电子设备、电动汽车、航空航天和军事工程等领域。为了在电动汽车和其他需要更高能量密度的领域进行应用，需要开发出高性能商业化应用正极材料的新材料。
磷酸铁锂(LiFePO4，LFP)作为一种的橄榄石结构的正极材料，其平台电压较低(3.3V，Li/Li+)，材料的能量密度相对较低。而同样具有橄榄石结构的磷酸锰铁锂(LiMnxFe1-xPO4，LMFP)材料具有与磷酸铁锂材料类似的高安全性能、较高的放电平台(4.1V，Li+/Li)以及磷铁锰储量丰富以及绿色无污染等优点。但是，由于其循环稳定性较弱、具有低电子电导率，限制了其进一步商业化应用。
因此，亟需设计合成具有较高电导率同时在高电压下具有较好循环稳定性的高性能磷酸锰铁锂正极材料。
鉴于此，特提出本公开。
发明内容
本公开的目的包括提供一种磷酸锰铁锂正极材料、极片及其制备方法和应用，旨在使材料具有高电导率，同时还在高电压下具有较好的电化学性能。
为了实现本公开的上述目的，可采用以下技术方案：
第一方面，本公开提供的方案包括一种磷酸锰铁锂正极材料，包括磷酸锰铁锂基材，在磷酸锰铁锂基材上包覆有碳层，且磷酸锰铁锂正极材料中含有超离子导电体；
超离子导电体选自磷酸钛锆、磷酸钛钇、磷酸钒锆和磷酸钒钇中的至少一种。
在本公开的一些实施方式中，磷酸锰铁锂基材的表面还包覆有碳层，部分超离子导电体与碳层共同包覆在磷酸锰铁锂基材的表面，部分超离子导电体分布于磷酸锰铁锂基材的内部。
在本公开的一些实施方式中，超离子导电体在磷酸锰铁锂正极材料中的质量分数 为0.25％-6.0％。
在本公开的一些实施方式中，以质量分数计，在磷酸锰铁锂正极材料中，含碳量为1％-3％。
在本公开的一些实施方式中，磷酸锰铁锂正极材料的中值粒度为0.4μm-5.0μm，比表面积为5m2/g-13m2/g。
在本公开的一些实施方式中，磷酸锰铁锂基材的化学式为LiMnxAyFezPO4，其中，掺杂元素A选自Cu、Ti、Zr、Cr、Y、Co和Ni中的至少一种，x+y+z＝1，0＜x＜1，0＜y＜1，0＜z＜1。
在本公开的一些实施方式中，在磷酸锰铁锂正极材料中，A元素的质量分数为0.005％-6％。
第二方面，本公开提供的方案还包括一种磷酸锰铁锂正极材料的制备方法，包括：在磷酸锰铁锂基材上形成碳层，并引入超离子导电体
在本公开的一些实施方式中，将待改性磷酸锰铁、凝胶材料、超离子导电体与锂源混合得到混合物料，将混合物料进行加热脱水，再进行烧结。
在本公开的一些实施方式中，待改性磷酸锰铁、凝胶材料和超离子导电体的质量比为100：(2-15)：(0.4-8)。
在本公开的一些实施方式中，凝胶材料为玉米淀粉凝胶。
在本公开的一些实施方式中，加热脱水的过程中控制加热温度为110℃-200℃，加热时间为2h-4h。
在本公开的一些实施方式中，在通入空气的条件下进行加热脱水，完成之后降温至室温后进行球磨，然后在进行烧结。
在本公开的一些实施方式中，烧结的过程中，控制烧结温度为500℃-1100℃，烧结时间为8h-30h。
在本公开的一些实施方式中，烧结的过程在惰性气氛下进行，在烧结完成之后，退火至室温，再进行球磨、过筛。
在本公开的一些实施方式中，混合物料的制备过程包括：将待改性磷酸锰铁、凝胶材料和超离子导电体在加热条件下混合，再与锂源混合。
在本公开的一些实施方式中，在加热条件下混合的过程中，控制加热温度为50℃-70℃。
在本公开的一些实施方式中，通过控制锂源的加入量，使待改性磷酸锰铁中的金属元素总量与锂源中的锂元素的摩尔比为(0.9-1.1)：(1.0-1.3)。
在本公开的一些实施方式中，锂源选自正丁基锂、氢氧化锂、硝酸锂、草酸锂、 碳酸锂、醋酸锂和氧化锂中的至少一种。
在本公开的一些实施方式中，待改性磷酸锰铁为掺杂有元素A的材料，待改性磷酸锰铁的化学式为MnxAyFezPO4，其中，掺杂元素A选自Cu、Ti、Zr、Cr、Y、Co和Ni中的至少一种，x+y+z＝1，0＜x＜1，0＜y＜1，0＜z＜1。
在本公开的一些实施方式中，待改性磷酸锰铁的制备过程包括：将磷酸锰铁与含有A元素的可溶性盐溶液在络合剂存在的条件下反应，反应过程中控制pH值为9-14。
在本公开的一些实施方式中，络合剂为氨水溶液，氨水溶液中氨的质量分数为0.03％-0.15％。
在本公开的一些实施方式中，1kg磷酸锰铁对应氨水溶液的用量为3L-15L。
在本公开的一些实施方式中，可溶性盐溶液中A元素的含量与磷酸锰铁的质量比为0.0001-0.10:1。
在本公开的一些实施方式中，可溶性盐溶液中A元素的含量与磷酸锰铁的质量比为0.01-0.05:1。
在本公开的一些实施方式中，可溶性盐溶液的浓度为0.002M-0.03M，1kg磷酸锰铁对应可溶性盐溶液的体积分别为0.2L-3L。
在本公开的一些实施方式中，可溶性盐溶液选自硫酸盐、氯化盐和硝酸盐中的至少一种。
在本公开的一些实施方式中，在制备待改性磷酸锰铁的过程中，控制反应温度为90℃-130℃，反应时间为3h-30h。
在本公开的一些实施方式中，磷酸锰铁的制备过程包括：将铁盐、锰盐和磷酸盐混合反应，控制原料中锰、铁、磷的摩尔比为(0.10～0.80)：(0.20～0.90)：(1.0～1.3)，控制得到的磷酸锰铁的中值粒径为0.12μm-10μm。
在本公开的一些实施方式中，磷酸锰铁的制备过程中，控制反应温度为500℃-900℃，反应时间为8h-36h。
第三方面，本公开提供的方案还包括一种磷酸锰铁锂正极极片，包括正极集流体，在正极集流体上附着有正极活性涂层，在正极活性涂层中含有上述任意实施方式中的磷酸锰铁锂正极材料或上述任意实施方式中的制备方法制备得到的磷酸锰铁锂正极材料。
在本公开的一些实施方式中，正极活性涂层中还含有粘结剂、调节剂和导电剂，磷酸锰铁锂正极材料、粘结剂、调节剂和导电剂的质量比为(80-98.7)：(0.2-8)：(0.1～5)：(1-7)。
在本公开的一些实施方式中，磷酸锰铁锂正极材料、粘结剂、调节剂和导电剂的 质量比为(93-97)：(0.5-2)：(0.5～2)：(2-3)。
在本公开的一些实施方式中，调节剂为聚丙烯酸钠、聚轮烷、聚丙烯酰胺和聚乙烯亚胺中的至少一种。
在本公开的一些实施方式中，导电剂选自导电炭黑、乙炔黑、石墨和石墨烯中的至少一种。
在本公开的一些实施方式中，粘结剂选自瓜尔胶、海藻酸钠、羧基甲基纤维素钠、阿拉伯树胶、角叉菜胶、丁苯橡胶和聚偏氟乙烯中的至少一种。
在本公开的一些实施方式中，正极集流体为铝箔。
第四方面，本公开提供的方案还包括一种上述任意实施方式中的磷酸锰铁锂正极极片的制备方法，包括：在正极集流体上形成正极活性涂层，并使正极活性涂层中含有磷酸锰铁锂正极材料。
在本公开的一些实施方式中，磷酸锰铁锂正极材料、粘结剂、调节剂和导电剂混合，再与溶剂混合均浆得到正极浆料，将正极浆料涂覆于正极集流体的至少一面，之后进行干燥；
其中，正极浆料的粘度为3000mPa.s-8500mPa.s。
第四方面，本公开提供的方案还包括一种锂电池，包括上述任意实施方式中的磷酸锰铁锂正极极片或上述任意实施方式中的制备方法制备得到的磷酸锰铁锂正极极片。
第五方面，本公开提供的方案还包括一种用电装置，包括上述任意实施方式中的锂电池。
通过在磷酸锰铁锂基材上引入超离子导电体，配合对超离子导电体的种类进行选择优化，使引入的超离子导电体有较强的导电能力，进而改善颗粒的导电性能，提高正极材料的电导率；同时促进了离子在正极颗粒之间的传输，提高正极材料的循环性能。此外，超离子导电体以及碳层的存在可以更大限度地降低电解液与铁、锰的直接接触，从而改善了正极颗粒表面与电解液副反应，能够稳定磷酸锰铁锂正极颗粒内部结构，进而改善材料的电化学性能。
附图说明
为了更清楚地说明本公开实施例的技术方案，下面将对实施例中所需要使用的附图作简单地介绍，应当理解，以下附图仅示出了本公开的某些实施例，因此不应被看作是对范围的限定，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他相关的附图。
图1为本公开所提供磷酸锰铁锂正极片的制备工艺流程图；
图2为实施例1的磷酸锰铁锂正极材料的XRD图；
图3为实施例1的磷酸锰铁锂正极材料的SEM图。
具体实施方式
下面将结合实施例对本公开的实施方案进行详细描述，但是本领域技术人员将会理解，下列实施例仅用于说明本公开，而不应视为限制本公开的范围。实施例中未注明具体条件者，按照常规条件或制造商建议的条件进行。所用试剂或仪器未注明生产厂商者，均为可以通过市售购买获得的常规产品。
在本公开中所披露的范围的端点和任何值都不限于该精确的范围或值，这些范围或值应当理解为包含接近这些范围或值的值。对于数值范围来说，各个范围的端点值之间、各个范围的端点值和单独的点值之间，以及单独的点值之间可以彼此组合而得到一个或多个新的数值范围，这些数值范围应被视为在本文中具体公开。
本公开实施例提供一种磷酸锰铁锂正极材料的制备方法，通过在磷酸锰铁锂基材上引入超离子导电体，能够使材料具有高电导率，同时还在高电压下具有较好的电化学性能。同时在磷酸锰铁锂基材表面引入碳层，利用超离子导电体以及碳层的存在可以更大限度地降低电解液与铁、锰的直接接触，从而改善了正极颗粒表面与电解液副反应，能够稳定磷酸锰铁锂正极颗粒内部结构，进而改善材料的电化学性能。
具体的制备方法可以参照图1，包括如下步骤：
S1、制备掺杂有A元素的待改性磷酸锰铁
待改性磷酸锰铁可以为掺杂有元素A的材料，此时待改性磷酸锰铁的化学式为MnxAyFezPO4，其中，掺杂元素A选自Cu、Ti、Zr、Cr、Y、Co和Ni中的至少一种，x+y+z＝1，0＜x＜1，0＜y＜1，0＜z＜1。
具体地，掺杂元素A可以为以上元素中的任意一种或几种，x、y、z的取值均可以是大于0且小于1，同时满足x+y+z＝1，可以根据需求进行元素比例的控制。
在一些实施例中，待改性磷酸锰铁的制备过程包括：将磷酸锰铁与含有A元素的可溶性盐溶液在络合剂存在的条件下反应，反应过程中控制pH值为9-14，以在磷酸锰铁中引入掺杂元素A。具体地，可以采用氢氧化钠溶液调节反应pH值。
在一些实施例中，络合剂可以为氨水溶液，氨水溶液中氨的质量分数为0.03％-0.15％，1kg磷酸锰铁对应氨水溶液的用量为3L-15L。通过控制氨水溶液的浓度和用量，以得到均匀的待改性磷酸锰铁。具体地，氨水溶液中氨的质量分数可以为0.03％、0.05％、0.08％、0.10％、0.12％、0.15％等，1kg磷酸锰铁对应氨水溶液的用量 可以为3L、5L、8L、10L、12L、15L等。
在一些实施例中，可溶性盐溶液中A元素的含量与磷酸锰铁的质量比为0.0001-0.10:1(如0.0001:1、0.0005:1、0.001:1、0.005:1、0.010:1、0.015:1、0.10:1等)，优选为0.01-0.05:1。在实际操作时，可溶性盐溶液的浓度为0.002M-0.03M，1kg磷酸锰铁对应可溶性盐溶液的体积分别为0.2L-3L，通过进一步控制可溶性盐溶液的浓度和用量，以控制元素A的掺杂量。可溶性盐溶液选自硫酸盐、氯化盐和硝酸盐中的至少一种，可以为以上任意一种或几种。
具体地，可溶性盐溶液中A元素的浓度可以为0.002M、0.005M、0.010M、0.020M、0.030M等，1kg磷酸锰铁对应可溶性盐溶液的体积可以为0.2L、0.5L、1.0L、2.0L、3.0L等。
在一些实施例中，在制备待改性磷酸锰铁的过程中，控制反应温度为90℃-130℃，反应时间为3h-30h，以使反应充分进行，提高原料利用率。具体地，反应温度可以为90℃、100℃、110℃、120℃、130℃等，反应时间可以为3h、5h、10h、15h、20h、25h、30h等，在反应完成只有进行冷却、洗涤、压滤。
进一步地，制备待改性磷酸锰铁的过程中所使用的磷酸锰铁可以为市购产品，也可以自主合成。在一些实施例中，磷酸锰铁的制备过程包括：将铁盐、锰盐和磷酸盐混合反应，控制原料中锰、铁、磷的摩尔比为(0.10～0.80)：(0.20～0.90)：(1.0～1.3)，控制得到的磷酸锰铁的中值粒径为0.12μm-10μm。磷酸锰铁的制备过程中，在惰性环境(如氮气氛围)下进行反应，控制反应温度为500℃-900℃，反应时间为8h-36h，通过控制反应时间，使制备得到的磷酸锰铁的中值粒径在上述范围内。
具体地，铁盐可以为但不限于磷酸铁，锰盐可以为但不限于硫酸锰，磷酸盐可以为但不限于磷酸铵。制备磷酸锰铁时，反应温度可以为500℃、600℃、700℃、800℃、900℃等，反应时间可以为8h、10h、20h、30h、36h等。
S2、制备含有待改性磷酸锰铁、凝胶材料、超离子导电体和锂源的混合物料
将待改性磷酸锰铁、凝胶材料、超离子导电体与锂源混合得到混合物料，备用。
在一些实施例中，待改性磷酸锰铁、凝胶材料和超离子导电体的质量比为100：(2-15)：(0.4-8)，通过控制凝胶材料和超离子导电体的用量以控制碳层的厚度以及超离子导电体的引入量，以进一步改善正极材料的电化学性能。具体地，改性磷酸锰铁、凝胶材料和超离子导电体的质量比可以为100:2:0.4、100:5:2.0、100:8:4.0、100:10:5.0、100:12:6.0、100:15:8.0等。
在一些实施例中，超离子导电体选自磷酸钛锆、磷酸钛钇、磷酸钒锆和磷酸钒钇中的至少一种，可以为以上任意一种或几种，优选为磷酸钛锆和磷酸钛钇中的至少一 种。凝胶材料为玉米淀粉凝胶。锂源选自正丁基锂、氢氧化锂、硝酸锂、草酸锂、碳酸锂、醋酸锂和氧化锂中的至少一种，可以为以上任意一种或几种。
在一些实施例中，混合物料的制备过程包括：将待改性磷酸锰铁、凝胶材料和超离子导电体在加热条件下混合，再与锂源混合，以提高混合的均匀度形成凝胶包覆。在加热条件下混合的过程中，控制加热温度为50℃-70℃，如可以为50℃、60℃、70℃等，混合过程在搅拌的条件下进行。
在一些实施例中，通过控制锂源的加入量，使待改性磷酸锰铁中的金属元素总量与锂源中的锂元素的摩尔比为(0.9-1.1)：(1.0-1.3)，如可以为0.9:1.0、1.0:1.1、1.1:1.3等。
S3、制备包覆的磷酸锰铁锂正极材料
将混合物料进行加热脱水，再进行烧结。在加热脱水的过程中可以多孔结构，部分超离子导电体进入正极颗粒之间，部分超离子导电体在烧结阶段与C形成双层包覆在正极材料的表面。
在一些实施例中，加热脱水的过程中控制加热温度为110℃-200℃，加热时间为2h-4h，可以在通入空气的条件下进行加热脱水，完成之后降温至室温后进行球磨，然后在进行烧结。在低温条件下缓慢脱除混合物料中的水分子，此时由于凝胶包覆层未固化，利用水分子在凝胶包覆层中的析出路径形成孔道，从而进行成孔。在加热脱水之后会有结块现象，通过球磨使颗粒分散均匀。
在一些实施例中，烧结的过程中，控制烧结温度为500℃-1100℃，烧结时间为8h-30h，烧结的过程可以在惰性气氛下进行，在烧结完成之后，退火至室温，再进行球磨、过筛，制备得到的磷酸锰铁锂正极材料的中值粒度为0.4μm-5.0μm，比表面积为5m2/g-13m2/g。
具体地，惰性气氛可以为氖气、氩气、氮气等，也可以在其他无氧环境下进行。烧结温度可以为500℃、600℃、700℃、800℃、900℃、1000℃、1100℃等，烧结时间可以为8h、10h、15h、20h、25h、30h等。
本公开实施还提供一种磷酸锰铁锂正极材料，包括磷酸锰铁锂基材，在磷酸锰铁锂基材上包覆有碳层，且磷酸锰铁锂正极材料中含有超离子导电体，超离子导电体选自磷酸钛锆、磷酸钛钇、磷酸钒锆和磷酸钒钇中的至少一种。
通过在磷酸锰铁锂基材中引入超离子导电体，配合对超离子导电体的种类进行选择优化，使引入的超离子导电体有较强的导电能力，进而改善颗粒的导电性能，提高正极材料的电导率；同时促进了离子在正极颗粒之间的传输，提高正极材料的循环性能。
在一些实施例中，磷酸锰铁锂基材的表面还包覆有碳层，部分超离子导电体与碳层共同包覆在磷酸锰铁锂基材的表面，部分超离子导电体分布于磷酸锰铁锂基材的内部。含超离子导电体以及碳层的存在可以最大限度地降低电解液与铁、锰的直接接触，从而改善了正极颗粒表面与电解液副反应，稳定磷酸锰铁锂正极颗粒内部结构，进而改善材料的电化学性能。
在一些实施例中，超离子导电体在磷酸锰铁锂正极材料中的质量分数为0.25％-6.0％(如0.25％、0.50％、1.0％、2.0％、3.0％、4.0％、5.0％、6.0％等)。以质量分数计，在磷酸锰铁锂正极材料中，含碳量为1％-3％(如1％、2％、3％等)。
在一些实施例中，磷酸锰铁锂基材的化学式为LiMnxAyFezPO4，其中，掺杂元素A选自Cu、Ti、Zr、Cr、Y、Co和Ni中的至少一种，x+y+z＝1，0＜x＜1，0＜y＜1，0＜z＜1。在磷酸锰铁锂晶格中掺入阳离子，形成具有阳离子缺陷的正极材料，使其电导率提高，极大地提高了磷酸锰铁锂的电化学性能。
在一些实施例中，在磷酸锰铁锂正极材料中，A元素的质量分数为0.005％-6％，通过控制A元素的掺杂量，以进一步提升正极材料的电化学性能。具体地，在磷酸锰铁锂正极材料中，A元素的质量分数可以为0.005％、0.01％、0.1％、1.0％、2.0％、3.0％、4.0％、5.0％、6.0％等。
本公开实施例还提供一种磷酸锰铁锂正极极片，包括正极集流体，在正极集流体上附着有正极活性涂层，在正极活性涂层中含有上述磷酸锰铁锂正极材料，利用磷酸锰铁锂正极材料的改进可以进一步提高磷酸锰铁锂正极极片的电化学性能。
在一些实施例中，正极活性涂层中还含有粘结剂、调节剂和导电剂，磷酸锰铁锂正极材料、粘结剂、调节剂和导电剂的质量比为(80-98.7)：(0.2-8)：(0.1～5)：(1-7)，优选为(93-97)：(0.5-2)：(0.5～2)：(2-3)。调节剂为聚丙烯酸钠、聚轮烷、聚丙烯酰胺和聚乙烯亚胺中的至少一种，可以为以上任意一种或几种。
需要说明的是，调节剂具有很高的粘结性能和良好的机械性能，特别是柔韧性较好，不会在切割极片的过程中出现崩裂；在电解液中不容易发生过多溶胀，与电解液接触基本不发生副反应；可以紧密将正极活性材料与集流体粘连，在循环过程中，能够稳定电极结构，抑制材料从极片脱落，从而提升电池的循环性能。
在一些实施例中，导电剂选自导电炭黑、乙炔黑、石墨和石墨烯中的至少一种，可以为以上任意一种或几种。粘结剂选自瓜尔胶、海藻酸钠、羧基甲基纤维素钠、阿拉伯树胶、角叉菜胶、丁苯橡胶和聚偏氟乙烯中的至少一种，可以为以上任意一种或几种。正极集流体可以但不限于铝箔。
本公开实施例还提供一种磷酸锰铁锂正极极片的制备方法，包括：在正极集流体 上形成正极活性涂层，并使正极活性涂层中含有上述实施方式中的磷酸锰铁锂正极材料。制备方法不限可以参照现有技术，如利用磷酸锰铁锂正极材料制备形成浆料，涂覆于正极集流体上，然后干燥。
在一些实施例中，磷酸锰铁锂正极材料、粘结剂、调节剂和导电剂混合，再与溶剂混合均浆得到正极浆料，将正极浆料涂覆于正极集流体的至少一面，之后进行干燥、冷压、切片，制得磷酸锰铁锂正极极片。其中，正极浆料的粘度为3000mPa.s-8500mPa.s。溶剂可以但不限于NMP，用于调节粘度在上述范围内。
具体地，正极浆料的粘度可以为3000mPa.s、4000mPa.s、5000mPa.s、6000mPa.s、7000mPa.s、8000mPa.s、8500mPa.s等。
本公开实施例还提供一种锂电池，包括上述磷酸锰铁锂正极极片，还可以包括负极极片、电解液、隔膜等形成一个完整的锂电池结构。
本公开实施例还提供一种用电装置，包括上述锂电池，还可以包括用电设备，具体种类不限。
以下结合实施例对本公开的特征和性能作进一步的详细描述。
实施例1
本实施例提供了一种磷酸锰铁锂正极极片的制备方法，包括如下步骤：
(1)将磷酸铁、硫酸锰和磷酸铵按照锰、铁、磷的摩尔比为0.43：0.57：1.15混合，在550℃的氮气环境下加热16h，得到中值粒度在3.4μm的磷酸锰铁，备用。将磷酸锰铁置于密闭反应釜内，注入氨质量分数为0.08wt％氨水溶液、0.017M的硫酸镍溶液(磷酸锰铁、氨水溶液、硫酸镍溶液按照1kg：5.5L：0.8L混合)，在95℃下加热12h，加氢氧化钠调控pH为11.3、搅拌、冷却、洗涤压滤，得到掺杂磷酸锰铁B(Mn0.427Ni0.003Fe0.57PO4)。
(2)将掺杂磷酸锰铁B、玉米淀粉凝胶、磷酸钛锆按照质量比100：2：0.75混合、搅拌以形成凝胶包覆，混合过程中控制加热温度为65℃，混合时间为5h(下同)，再加入碳酸锂(掺杂磷酸锰铁B中的金属与碳酸锂中的锂按照摩尔比为1.02：1.15的比例混合)，进行搅拌，既得混合物C。
(3)将混合物C送至加热炉中，110℃下通空气下，加热4h进行脱水，凝胶包覆层成孔，降温至室温后，送至740℃氮气环境下加热15h，退火至室温、干燥、球磨、过筛，得到包覆磷酸锰铁锂正极材料；
(4)将包覆磷酸锰铁锂正极材料、聚偏氟乙烯、聚丙烯酰胺、导电炭黑按照质量比96：0.5：0.5：3混合、搅拌，之后加入溶剂NMP、调节粘度至5000-5340mPa.s，单层涂覆于铝箔集流体上，干燥、辊压、切片，制得磷酸锰铁锂正极片。
实施例2
本实施例提供了一种磷酸锰铁锂正极极片的制备方法，包括如下步骤：
(1)将磷酸铁、硫酸锰和磷酸铵按照锰、铁、磷的摩尔比为0.30：0.70：1.15混合，在580℃的氮气环境下加热16h，得到中值粒度在4.5μm的磷酸锰铁，备用。将磷酸锰铁置于密闭反应釜内，注入氨质量分数为0.08wt％氨水溶液、0.017M的硫酸镍溶液(磷酸锰铁、氨水溶液、硫酸镍溶液按照1kg：5.5L：0.8L混合)，在95℃下加热12h，加氢氧化钠调控pH为10.3、搅拌、冷却、洗涤压滤，得到掺杂磷酸锰铁B(Mn0.297Ni0.003Fe0.70PO4)。
(2)将掺杂磷酸锰铁B、玉米淀粉凝胶、磷酸钛锆按照质量比100：2：1.5混合、搅拌以形成凝胶包覆，混合过程中控制加热温度为65℃，再加入碳酸锂(掺杂磷酸锰铁B中的金属与碳酸锂中的锂按照摩尔比为1.02：1.15的比例混合)，进行搅拌，既得混合物C。
(3)将混合物C送至加热炉中，115℃下通空气下，加热3.5h进行脱水，凝胶包覆层成孔，降温至室温后，送至740℃氮气环境下加热15h，退火至室温、干燥、球磨、过筛，得到包覆磷酸锰铁锂正极材料。
(4)将包覆磷酸锰铁锂正极材料、聚偏氟乙烯、聚丙烯酰胺、导电炭黑按照质量比96：0.5：0.5：3混合、搅拌、加入溶剂NMP、调节粘度至5000-5340mPa.s，单层涂覆于铝箔集流体上，干燥、辊压、切片，制得磷酸锰铁锂正极片。
实施例3
本实施例提供了一种磷酸锰铁锂正极极片的制备方法，包括如下步骤：
(1)将磷酸铁、硫酸锰和磷酸铵按照锰、铁、磷的摩尔比为0.45：0.55：1.15混合，在600℃的氮气环境下加热16h，得到中值粒度在4μm的磷酸锰铁，备用。将磷酸锰铁置于密闭反应釜内，注入氨质量分数为0.08wt％氨水溶液、0.017M的硫酸镍溶液(磷酸锰铁、氨水溶液、硫酸镍溶液按照1kg：5.5L：0.8L混合)，在95℃下加热12h，加氢氧化钠调控pH为11.3、搅拌、冷却、洗涤压滤，得到掺杂磷酸锰铁B(Mn0.447Ni0.003Fe0.55PO4)。
(2)将掺杂磷酸锰铁B、玉米淀粉凝胶、磷酸钛锆按照质量比100：2：0.75混合、搅拌以形成凝胶包覆，混合过程中控制加热温度为65℃，再加入碳酸锂(掺杂磷酸锰铁B中的金属与碳酸锂中的锂按照摩尔比为1.02：1.10的比例混合)，进行搅拌，既得混合物C。
(3)将混合物C送至加热炉中，110℃下通空气下，加热4h进行脱水，凝胶包覆层成孔，降温至室温后，送至740℃氮气环境下加热15h，退火至室温、干燥、球磨、过筛，得到包覆磷酸锰铁锂正极材料。
(4)将包覆磷酸锰铁锂正极材料、聚偏氟乙烯、聚丙烯酸钠、导电炭黑按照质量比95：1：1：3混合、搅拌、加入溶剂NMP、调节粘度至6000-6300mPa.s，单层涂覆于铝箔集流体上，干燥、辊压、切片，制得磷酸锰铁锂正极片。
实施例4
本实施例提供了一种磷酸锰铁锂正极极片的制备方法，包括如下步骤：
(1)将磷酸铁、硫酸锰和磷酸铵按照锰、铁、磷的摩尔比为0.43：0.57：1.2混合，在600℃的氮气环境下加热16h，得到中值粒度在3.4μm的磷酸锰铁，备用。将磷酸锰铁置于密闭反应釜内，注入氨质量分数为0.08wt％氨水溶液、0.017M的硫酸镍溶液(磷酸锰铁、氨水溶液、硫酸镍溶液按照1kg：5.5L：0.8L混合)，在95℃下加热12h，加氢氧化钠调控pH为12、搅拌、冷却、洗涤压滤，得到掺杂磷酸锰铁B(Mn0.427Ni0.003Fe0.57PO4)。
(2)将掺杂磷酸锰铁B、玉米淀粉凝胶、磷酸钒钇按照质量比100：2：1.5混合、搅拌以形成凝胶包覆，混合过程中控制加热温度为65℃，再加入碳酸锂(掺杂磷酸锰铁B中的金属与碳酸锂中的锂按照摩尔比为1.02：1.10的比例混合)，进行搅拌，既得混合物C。
(3)将混合物C送至加热炉中，120℃下通空气下，加热3h进行脱水，凝胶包覆层成孔，降温至室温后，送至740℃氮气环境下加热15h，退火至室温、干燥、球磨、过筛，得到包覆磷酸锰铁锂正极材料。
(4)将包覆磷酸锰铁锂正极材料、聚偏氟乙烯、聚聚丙烯酸钠、导电炭黑按照质量比96：0.5：0.8：2.7混合、搅拌、加入溶剂NMP、调节粘度至5500-6000mPa.s，单层涂覆于铝箔集流体上，干燥、辊压、切片，制得磷酸锰铁锂正极片。
实施例5
本实施例提供了一种磷酸锰铁锂正极极片的制备方法，包括如下步骤：
(1)将磷酸铁、硫酸锰和磷酸铵按照锰、铁、磷的摩尔比为0.20：0.80：1.2混合，在700℃的氮气环境下加热16h，得到中值粒度在5μm的磷酸锰铁，备用。将磷酸锰铁置于密闭反应釜内，注入氨质量分数为0.08wt％氨水溶液、0.017M的硫酸钴溶液(磷酸锰铁、氨水溶液、硫酸钴溶液按照1kg：5.5L：0.8L混合)，在95℃下加热12h，加氢氧化钠调控pH为11.0、搅拌、冷却、洗涤压滤，得到掺杂磷酸锰铁B (Mn0.197Co0.003Fe0.80PO4)。
(2)将掺杂磷酸锰铁B、玉米淀粉凝胶、磷酸钒钇按照质量比100：2：1.5混合、搅拌以形成凝胶包覆，混合过程中控制加热温度为65℃，再加入碳酸锂(掺杂磷酸锰铁B中的金属与碳酸锂中的锂按照摩尔比为1.02：1.10的比例混合)，进行搅拌，既得混合物C。
(3)将混合物C送至加热炉中，130℃下通空气下，加热2.5h进行脱水，凝胶包覆层成孔，降温至室温后，送至740℃氮气环境下加热15h，退火至室温、干燥、球磨、过筛，得到包覆磷酸锰铁锂正极材料。
(4)将包覆磷酸锰铁锂正极材料、聚偏氟乙烯、聚丙烯酰胺、导电炭黑按照质量比96：0.5：0.5：3混合、搅拌、加入溶剂NMP、调节粘度至5000-5340mPa.s，单层涂覆于铝箔集流体上，干燥、辊压、切片，制得磷酸锰铁锂正极片。
实施例6
本实施例提供了一种磷酸锰铁锂正极极片的制备方法，包括如下步骤：
(1)将磷酸铁、硫酸锰和磷酸铵按照锰、铁、磷的摩尔比为0.20：0.80：1.2混合，在700℃的氮气环境下加热16h，得到中值粒度在5.0μm的磷酸锰铁，备用。将磷酸锰铁置于密闭反应釜内，注入氨质量分数为0.08wt％氨水溶液、0.017M的硫酸钴溶液(磷酸锰铁、氨水溶液、硫酸钴溶液按照1kg：5.5L：0.8L混合)，在95℃下加热12h，加氢氧化钠调控pH为11.0、搅拌、冷却、洗涤压滤，得到掺杂磷酸锰铁B(Mn0.197Co0.003Fe0.80PO4)。
(2)将掺杂磷酸锰铁B、玉米淀粉凝胶、磷酸钛锆按照质量比100：2：3混合、搅拌以形成凝胶包覆，混合过程中控制加热温度为65℃，再加入碳酸锂(掺杂磷酸锰铁B中的金属与碳酸锂中的锂按照摩尔比为1.02：1.10的比例混合)，进行搅拌，既得混合物C。
(3)将混合物C送至加热炉中，120℃下通空气下，加热4h进行脱水，凝胶包覆层成孔，降温至室温后，送至740℃氮气环境下加热15h，退火至室温、干燥、球磨、过筛，得到包覆磷酸锰铁锂正极材料。
(4)将包覆磷酸锰铁锂正极材料、聚偏氟乙烯、聚丙烯酰胺、导电炭黑按照质量比96：0.5：0.5：3混合、搅拌、加入溶剂NMP、调节粘度至5000-5340mPa.s，单层涂覆于铝箔集流体上，干燥、辊压、切片，制得磷酸锰铁锂正极片。
实施例7
本实施例提供了一种磷酸锰铁锂正极极片的制备方法，与实施例6的区别主要在 于：制备过程中不引入聚丙烯酰胺。具体步骤如下：
(1)将磷酸铁、硫酸锰和磷酸铵按照锰、铁、磷的摩尔比为0.20：0.80：1.2混合，在700℃的氮气环境下加热16h，得到中值粒度在5.0μm的磷酸锰铁，备用。将磷酸锰铁置于密闭反应釜内，注入氨质量分数为0.08wt％氨水溶液、0.017M的硫酸钴溶液(磷酸锰铁、氨水溶液、硫酸钴溶液按照1kg：5.5L：0.8L混合)，在95℃下加热12h，加氢氧化钠调控pH为11.0、搅拌、冷却、洗涤压滤，得到掺杂磷酸锰铁B(Mn0.197Co0.003Fe0.80PO4)。
(2)将掺杂磷酸锰铁B、玉米淀粉凝胶、磷酸钛锆按照质量比100：2：3混合、搅拌、凝胶包覆，加热控制温度在65℃，再加入碳酸锂(掺杂磷酸锰铁B中的磷酸与碳酸锂中的锂按照摩尔比为1.02：1.10的比例混合)，进行搅拌，既得混合物C。
(3)将混合物C送至加热炉中，120℃下通空气下，加热4h进行脱水，凝胶包覆层成孔，降温至室温后，送至740℃氮气环境下加热15h，退火至室温、干燥、球磨、过筛，得到包覆磷酸锰铁锂正极材料。
(4)将包覆磷酸锰铁锂正极材料、聚偏氟乙烯、导电炭黑按照质量比96：1：3混合、搅拌、加入溶剂NMP、调节粘度至5000-5340mPa.s，单层涂覆于铝箔集流体上，干燥、辊压、切片，制得磷酸锰铁锂正极片。
对比例1
本对比例提供了一种磷酸锰铁锂正极极片的制备方法，本对比例与实施例1的区别主要在于：制备过程中不加入玉米淀粉凝胶。具体步骤如下：
(1)将磷酸铁、硫酸锰和磷酸铵按照锰、铁、磷的摩尔比为0.43：0.57：1.15混合，在550℃的氮气环境下加热16h，得到中值粒度在3.4μm的磷酸锰铁，备用。将磷酸锰铁置于密闭反应釜内，注入氨质量分数为0.08wt％氨水溶液、0.017M的硫酸镍溶液(磷酸锰铁、氨水溶液、硫酸镍溶液按照1kg：5.5L：0.8L混合)，在95℃下加热12h，加氢氧化钠调控pH为11.3、搅拌、冷却、洗涤压滤，得到掺杂磷酸锰铁B(Mn0.427Ni0.003Fe0.57PO4)
(2)将掺杂磷酸锰铁B、磷酸钛锆按照质量比100：1.5混合、搅拌，加热控制温度在65℃，再加入碳酸锂(掺杂磷酸锰铁B中的金属与碳酸锂中的锂按照摩尔比为1.02：1.15的比例混合)，进行搅拌，既得混合物C。
(3)将混合物C送至加热炉中，在740℃氮气环境下加热15h，退火至室温、干燥、球磨、过筛，得到包覆磷酸锰铁锂正极材料。
(4)将包覆磷酸锰铁锂正极材料、聚偏氟乙烯、聚丙烯酰胺、导电炭黑按照质量比96：0.5：0.5：3混合、搅拌、加入溶剂NMP、调节粘度至5000-5340mPa.s，单层涂覆于铝箔集流体上，干燥、辊压、切片，制得磷酸锰铁锂正极片。
对比例2
本对比例提供了一种磷酸锰铁锂正极极片的制备方法，与实施例1的区别主要在于：制备过程中不加入磷酸钛锆。具体步骤如下：
(1)将磷酸铁、硫酸锰和磷酸铵按照锰、铁、磷的摩尔比为0.43：0.57：1.15混合，在550℃的氮气环境下加热16h，得到中值粒度在3.4μm的磷酸锰铁，备用。将磷酸锰铁置于密闭反应釜内，注入氨质量分数为0.08wt％氨水溶液、0.017M的硫酸镍溶液(磷酸锰铁、氨水溶液、硫酸镍溶液按照1kg：5.5L：0.8L混合)，在95℃下加热12h，加氢氧化钠调控pH为11.3、搅拌、冷却、洗涤压滤，得到掺杂磷酸锰铁B(Mn0.427Ni0.003Fe0.57PO4)
(2)将掺杂磷酸锰铁B、玉米淀粉凝胶按照质量比100：2混合、搅拌以形成凝胶包覆，混合过程中控制加热温度为65℃，再加入碳酸锂(掺杂磷酸锰铁B中的金属与碳酸锂中的锂按照摩尔比为1.02：1.15的比例混合)，进行搅拌，既得混合物C。
(3)将混合物C送至加热炉中，110℃下通空气下，加热4h进行脱水，凝胶包覆层成孔，降温至室温后，送至740℃氮气环境下加热15h，退火至室温、干燥、球磨、水洗、干燥、过筛、除磁，得到包覆磷酸锰铁锂正极材料。
(4)将包覆磷酸锰铁锂正极材料、聚偏氟乙烯、聚丙烯酰胺、导电炭黑按照质量比96：0.5：0.5：3混合、搅拌、加入溶剂NMP、调节粘度至5000-5340mPa.s，单层涂覆于铝箔集流体上，干燥、辊压、切片，制得磷酸锰铁锂正极片。
对比例3
本对比例提供了一种磷酸锰铁锂正极极片的制备方法，与实施例5的区别主要在于：制备过程中不加入磷酸钒钇。具体步骤如下：
(1)将磷酸铁、硫酸锰和磷酸铵按照锰、铁、磷的摩尔比为0.20：0.80：1.2混合，在700℃的氮气环境下加热16h，得到中值粒度在5μm的磷酸锰铁，备用。将磷酸锰铁置于密闭反应釜内，注入氨质量分数为0.08wt％氨水溶液、0.017M的硫酸钴溶液(磷酸锰铁、氨水溶液、硫酸钴溶液按照1kg：5.5L：0.8L混合)，在95℃下加热12h，加氢氧化钠调控pH为11.0、搅拌、冷却、洗涤压滤，得到掺杂磷酸锰铁B(Mn0.197Co0.003Fe0.80PO4)。
(2)将掺杂磷酸锰铁B、玉米淀粉凝胶按照质量比100：2，混合、搅拌以形成凝 胶包覆，混合过程中控制加热温度为65℃，再加入碳酸锂(掺杂磷酸锰铁B中的金属与碳酸锂中的锂按照摩尔比为1.02：1.10的比例混合)，进行搅拌，既得混合物C。
(3)将混合物C送至加热炉中，130℃下通空气下，加热2.5h进行脱水，降温至室温后，送至740℃氮气环境下加热15h，退火至室温、干燥、球磨、过筛，得到包覆磷酸锰铁锂正极材料。
(4)将包覆磷酸锰铁锂正极材料、聚偏氟乙烯、聚丙烯酰胺、导电炭黑按照质量比96：0.5：0.5：3混合、搅拌、加入溶剂NMP、调节粘度至5000-5340mPa.s，单层涂覆于铝箔集流体上，干燥、辊压、切片，制得磷酸锰铁锂正极片。
对比例4
本对比例提供了一种磷酸锰铁锂正极极片的制备方法，与实施例6的区别主要在于：将磷酸钛锆替换为等量的磷酸钛钾。具体步骤如下：
(1)将磷酸铁、硫酸锰和磷酸铵按照锰、铁、磷的摩尔比为0.20：0.80：1.2混合，在700℃的氮气环境下加热16h，得到中值粒度在5.0μm的磷酸锰铁，备用。将磷酸锰铁置于密闭反应釜内，注入氨质量分数为0.08wt％氨水溶液、0.017M的硫酸钴溶液(磷酸锰铁、氨水溶液、硫酸钴溶液按照1kg：5.5L：0.8L混合)，在95℃下加热12h，加氢氧化钠调控pH为11.0、搅拌、冷却、洗涤压滤，得到掺杂磷酸锰铁B(Mn0.197Co0.003Fe0.80PO4)
(2)将掺杂磷酸锰铁B、玉米淀粉凝胶、磷酸钛钾按照质量比100：2：3混合、搅拌、凝胶包覆，加热控制温度在65℃，再加入碳酸锂(掺杂磷酸锰铁B中的金属与碳酸锂中的锂按照摩尔比为1.02：1.10的比例混合)，进行搅拌，既得混合物C。
(3)将混合物C送至加热炉中，120℃下通空气下，加热4h进行脱水，凝胶包覆层成孔，降温至室温后，送至740℃氮气环境下加热15h，退火至室温、干燥、球磨、过筛，得到包覆磷酸锰铁锂正极材料。
(4)将包覆磷酸锰铁锂正极材料、聚偏氟乙烯、聚丙烯酰胺、导电炭黑按照质量比96：0.5：0.5：3混合、搅拌、加入溶剂NMP、调节粘度至5000-5340mPa.s，单层涂覆于铝箔集流体上，干燥、辊压、切片，制得磷酸锰铁锂正极片。
试验例1
测试实施例1制备得到的磷酸锰铁锂正极材料的XRD图，如图2所示。测试实施例1制备得到的磷酸锰铁锂正极材料的SEM图，如图3所示。
从图2可以看出，本发明制备的磷酸锰铁晶型较好，无杂相产生。
从图3可以看出，本发明制备的磷酸铁锂的粒径较小，晶粒堆叠一起，导电网络 覆盖，缩短锂离子传输路径，进一步增大锂离子的迁移速率。
试验例2
测试实施例和对比例制备得到正极极片的性能，结果如表1和表2所示。
测试方法：(1)用比表面积测试仪测定正极材料的比表面积SSa值、激光粒度仪测定正极材料的中值粒度D50。(2)用粉末电导率测试仪测试实施例和对比例的正极材料的导电率，采用拉力试验机进行测试极片剥离强度。(3)实施例和对比例制备的正极极片放置在真空烘箱内进行干燥(80℃，3h)；并冲切成直径为12mm的圆片。在半电池中，正极使用干燥的电极片，正极使用锂片为对电极，隔膜为PP和PE复合隔膜，电解液：1M LiPF6的EC、DMC、DEC(体积比为1：1：1)。(4)利用CT2001A型电池检测系统对制备的半电池，截止电压为2.0-4.3V。先0.1C下恒流充至4.3V，再恒压4.3V充至电流≤0.05C，在0.1C下进行放电性能测试。
表1实施例和对比例正极材料比表面积SSa、粒度、电导率、剥离强度
从表1中，在实施例1-7和对比例1-4磷酸锰铁锂正极材料的比表面积和粒度相差不大，但其电导率和剥离强度有一定差异。实施例1-7的电导率要明显高于对比例1-3的，实施例7在制作正极片的时候未添加调节剂，导致极片的剥离强度较低。对比例1的电导率较低的原因为未添加凝胶，使得材料表面无碳层包覆，进而电导率未得到较大改善。对比例2、3的电导率更低的原因为未添加超离子导体，导致电导率较低。对比例4电导率较低的原因为包覆的超离子导体为本发明优选范围之外，电导率提升少， 不及实施例。
表2实施例和对比例提供电池的电性能
从表2测试结果可以看出实施例1-6和对比例1-4制备的半电池首次放电比容量分别在155.7～160.3mAh/g、145.4～156.2mAh/g之间。实施例1-7的首次库伦效率及300圈循环容量保持率均优于对比例1-4；实施例7在极片制备过程中调节剂，导致剥离强度低，在循环过程中可能存在极片脱落现象，进而在300圈循环后，容量保持率相对较低。对比例1的首次放电比容量较低的原因为，其在制备过程中未添加玉米淀粉凝胶，无法形成C包覆，最终导致电导率低。对比例2、3放电比容量较低，其原因为制备过程中未加入超离子导体，导致电导率较低，最终影响放电比容量的发挥。对比例4容量及循环保持率较低的原因为包覆的超离子导体为本发明优选范围之外，其电导率的提升能力有限。相对而言，实施例在电化学性能上的表现是较优的。
工业实用性
本公开通过在磷酸锰铁锂基材中引入超离子导电体，配合对超离子导电体的种类进行选择优化，使引入的超离子导电体有较强的导电能力，进而改善颗粒的导电性能和循环性能。通过在极片制备过程中，引入的调节剂，可以使极片在电解液中不容易发生过多溶胀，可以紧密将正极活性材料与集流体粘连，在循环过程中，能够稳定电极结构，抑制材料从极片脱落，从而提升电池的循环性能。本公开所提供的制备方法 操作方便，具有非常好的工业实用性。

Claims (38)

  1. 一种磷酸锰铁锂正极材料，其特征在于，包括磷酸锰铁锂基材，在所述磷酸锰铁锂基材上包覆有碳层，且所述磷酸锰铁锂正极材料中含有超离子导电体；
    所述超离子导电体选自磷酸钛锆、磷酸钛钇、磷酸钒锆和磷酸钒钇中的至少一种。
  2. 根据权利要求1所述的磷酸锰铁锂正极材料，其特征在于，部分所述超离子导电体与所述碳层共同包覆在所述磷酸锰铁锂基材的表面，部分所述超离子导电体分布于所述磷酸锰铁锂基材的内部。
  3. 根据权利要求1或2中任一项所述的磷酸锰铁锂正极材料，其特征在于，所述超离子导电体在所述磷酸锰铁锂正极材料中的质量分数为0.25％-6.0％。
  4. 根据权利要求3所述的磷酸锰铁锂正极材料，其特征在于，以质量分数计，在所述磷酸锰铁锂正极材料中，含碳量为1％-3％。
  5. 根据权利要求3或4所述的磷酸锰铁锂正极材料，其特征在于，所述磷酸锰铁锂正极材料的中值粒度为0.4μm-5.0μm，比表面积为5m2/g-13m2/g。
  6. 根据权利要求1-5中任一项所述的磷酸锰铁锂正极材料，其特征在于，所述磷酸锰铁锂基材的化学式为LiMnxAyFezPO4，其中，掺杂元素A选自Cu、Ti、Zr、Cr、Y、Co和Ni中的至少一种，x+y+z＝1，0＜x＜1，0＜y＜1，0＜z＜1。
  7. 根据权利要求6所述的磷酸锰铁锂正极材料，其特征在于，在所述磷酸锰铁锂正极材料中，A元素的质量分数为0.005％-6％。
  8. 一种权利要求1-7中任一项所述的磷酸锰铁锂正极材料的制备方法，其特征在于，包括：在所述磷酸锰铁锂基材上形成所述碳层，并引入所述超离子导电体。
  9. 根据权利要求8所述的制备方法，其特征在于，将待改性磷酸锰铁、凝胶材料、所述超离子导电体与锂源混合得到混合物料，将所述混合物料进行加热脱水，再进行烧结。
  10. 根据权利要求9所述的制备方法，其特征在于，所述待改性磷酸锰铁、所述凝胶材料和所述超离子导电体的质量比为100：(2-15)：(0.4-8)。
  11. 根据权利要求10所述的制备方法，其特征在于，所述凝胶材料为玉米淀粉凝胶。
  12. 根据权利要求9-11中任一项所述的制备方法，其特征在于，所述加热脱水的过程中控制加热温度为110℃-200℃，加热时间为2h-4h。
  13. 根据权利要求9-12中任一项所述的制备方法，其特征在于，在通入空气的条件下进行加热脱水，完成之后降温至室温后进行球磨，然后在进行烧结。
  14. 根据权利要求9-13中任一项所述的制备方法，其特征在于，所述烧结的过程中，控制烧结温度为500℃-1100℃，烧结时间为8h-30h。
  15. 根据权利要求14所述的制备方法，其特征在于，烧结的过程在惰性气氛下进行，在烧结完成之后，退火至室温，再进行球磨、过筛。
  16. 根据权利要求9-15中任一项所述的制备方法，其特征在于，所述混合物料的制备过程包括：将所述待改性磷酸锰铁、所述凝胶材料和所述超离子导电体在加热条件下混合，再与所述锂源混合。
  17. 根据权利要求16所述的制备方法，其特征在于，在加热条件下混合的过程中，控制加热温度为50℃-70℃。
  18. 根据权利要求9-17中任一项所述的制备方法，其特征在于，通过控制所述锂源的加入量，使所述待改性磷酸锰铁中的金属元素总量与所述锂源中的锂元素的摩尔比为(0.9-1.1)：(1.0-1.3)。
  19. 根据权利要求9-18中任一项所述的制备方法，其特征在于，所述锂源选自正丁基锂、氢氧化锂、硝酸锂、草酸锂、碳酸锂、醋酸锂和氧化锂中的至少一种。
  20. 根据权利要求9-19中任一项所述的制备方法，其特征在于，所述待改性磷酸锰铁为掺杂有元素A的材料，所述待改性磷酸锰铁的化学式为MnxAyFezPO4，其中，掺杂元素A选自Cu、Ti、Zr、Cr、Y、Co和Ni中的至少一种，x+y+z＝1，0＜x＜1，0＜y＜1，0＜z＜1。
  21. 根据权利要求20所述的制备方法，其特征在于，所述待改性磷酸锰铁的制备过程包括：将磷酸锰铁与含有A元素的可溶性盐溶液在络合剂存在的条件下反应，反应过程中控制pH值为9-14。
  22. 根据权利要求21所述的制备方法，其特征在于，所述络合剂为氨水溶液，所述氨水溶液中氨的质量分数为0.03％-0.15％，1kg所述磷酸锰铁对应所述氨水溶液的用量为3L-15L。
  23. 根据权利要求21或22所述的制备方法，其特征在于，所述可溶性盐溶液中A元素的含量与磷酸锰铁的质量比为0.0001-0.10:1。
  24. 根据权利要求23所述的制备方法，其特征在于，所述可溶性盐溶液中A元素的含量与磷酸锰铁的质量比为0.01-0.05:1。
  25. 根据权利要求23或24所述的制备方法，其特征在于，所述可溶性盐溶液的浓度为0.002M-0.03M，1kg所述磷酸锰铁对应所述可溶性盐溶液的体积分别为0.2L-3L，所述可溶性盐溶液选自硫酸盐、氯化盐和硝酸盐中的至少一种。
  26. 根据权利要求21-25中任一项所述的制备方法，其特征在于，在制备所述待改性磷酸锰铁的过程中，控制反应温度为90℃-130℃，反应时间为3h-30h。
  27. 根据权利要求21-26中任一项所述的制备方法，其特征在于，所述磷酸锰铁的 制备过程包括：将铁盐、锰盐和磷酸盐混合反应，控制原料中锰、铁、磷的摩尔比为(0.10～0.80)：(0.20～0.90)：(1.0～1.3)，控制得到的磷酸锰铁的中值粒径为0.12μm-10μm。
  28. 根据权利要求27所述的制备方法，其特征在于，在制备所述磷酸锰铁的过程中，控制反应温度为500℃-900℃，反应时间为8h-36h。
  29. 一种磷酸锰铁锂正极极片，其特征在于，包括正极集流体，在所述正极集流体上附着有正极活性涂层，在所述正极活性涂层中含有权利要求1-7中任一项所述的磷酸锰铁锂正极材料或权利要求8-28中任一项所述制备方法制备得到的磷酸锰铁锂正极材料。
  30. 根据权利要求29所述的磷酸锰铁锂正极极片，其特征在于，所述正极活性涂层中还含有粘结剂、调节剂和导电剂，所述磷酸锰铁锂正极材料、所述粘结剂、所述调节剂和所述导电剂的质量比为(80-98.7)：(0.2-8)：(0.1～5)：(1-7)。
  31. 根据权利要求30所述的磷酸锰铁锂正极极片，其特征在于，所述磷酸锰铁锂正极材料、所述粘结剂、所述调节剂和所述导电剂的质量比为(93-97)：(0.5-2)：(0.5～2)：(2-3)。
  32. 根据权利要求30或31所述的磷酸锰铁锂正极极片，其特征在于，所述调节剂为聚丙烯酸钠、聚轮烷、聚丙烯酰胺和聚乙烯亚胺中的至少一种。
  33. 根据权利要求30-32中任一项所述的磷酸锰铁锂正极极片，其特征在于，所述导电剂选自导电炭黑、乙炔黑、石墨和石墨烯中的至少一种。
  34. 根据权利要求30-33中任一项所述的磷酸锰铁锂正极极片，其特征在于，所述粘结剂选自瓜尔胶、海藻酸钠、羧基甲基纤维素钠、阿拉伯树胶、角叉菜胶、丁苯橡胶和聚偏氟乙烯中的至少一种。
  35. 一种权利要求20-34中任一项所述的磷酸锰铁锂正极极片的制备方法，其特征在于，包括：在所述正极集流体上形成所述正极活性涂层，并使所述正极活性涂层中含有所述磷酸锰铁锂正极材料。
  36. 根据权利要求35所述的制备方法，其特征在于，将所述磷酸锰铁锂正极材料、粘结剂、调节剂和导电剂混合，再与溶剂混合均浆得到正极浆料，将所述正极浆料涂覆于所述正极集流体的至少一面，之后进行干燥；
    其中，所述正极浆料的粘度为3000mPa.s-8500mPa.s。
  37. 一种锂电池，其特征在于，包括权利要求29-34中任一项所述的磷酸锰铁锂正极极片或权利要求35-36中任一项所述制备方法制备得到的磷酸锰铁锂正极极片。
  38. 一种用电装置，其特征在于，包括权利要求37所述的锂电池。
PCT/CN2023/101395 2023-06-20 2023-06-20 一种磷酸锰铁锂正极材料、极片及其制备方法和应用 Ceased WO2024259587A1 (zh)

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