WO2024119663A1 - 一种磷酸锰铁锂正极材料、其制备方法及电池 - Google Patents

一种磷酸锰铁锂正极材料、其制备方法及电池 Download PDF

Info

Publication number
WO2024119663A1
WO2024119663A1 PCT/CN2023/082550 CN2023082550W WO2024119663A1 WO 2024119663 A1 WO2024119663 A1 WO 2024119663A1 CN 2023082550 W CN2023082550 W CN 2023082550W WO 2024119663 A1 WO2024119663 A1 WO 2024119663A1
Authority
WO
WIPO (PCT)
Prior art keywords
source
lithium
manganese
boron
iron
Prior art date
Application number
PCT/CN2023/082550
Other languages
English (en)
French (fr)
Inventor
李爱霞
余海军
谢英豪
李长东
Original Assignee
广东邦普循环科技有限公司
湖南邦普循环科技有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 广东邦普循环科技有限公司, 湖南邦普循环科技有限公司 filed Critical 广东邦普循环科技有限公司
Publication of WO2024119663A1 publication Critical patent/WO2024119663A1/zh

Links

Classifications

    • 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 battery materials, and in particular to a lithium manganese iron phosphate positive electrode material, a preparation method thereof and a battery.
  • Lithium manganese iron phosphate has become a research hotspot due to its higher voltage platform and high specific energy density. Although the voltage platform, conductivity and lithium ion conductivity of lithium manganese iron phosphate have been improved compared with lithium iron phosphate and lithium manganese phosphate, the conductivity of single lithium manganese iron phosphate is still very poor. Pure lithium manganese iron phosphate is almost an insulator, and it is difficult to give full play to the electrochemical properties of the material.
  • the electrochemical performance of lithium manganese iron phosphate is generally improved by ion doping, conductive phase carbon coating, particle size nano-sizing and morphology control.
  • too much conductive agent and carbon coating will reduce the gram capacity of the positive electrode material, resulting in a decrease in rate performance and cycle performance. Therefore, it is urgent to study a method to improve the conductivity and electrochemical performance of lithium manganese iron phosphate without affecting the gram capacity.
  • the object of the present invention is to provide a lithium manganese iron phosphate positive electrode material, a preparation method thereof and a battery, aiming to improve the conductivity and electrochemical properties of lithium manganese iron phosphate without affecting the gram capacity.
  • the present invention is achieved in that:
  • the present invention provides a lithium iron manganese phosphate positive electrode material, comprising: lithium iron manganese phosphate particles, in which boron is doped, and the doping amount of boron gradually decreases from the inside to the outside of the lithium iron manganese phosphate particles.
  • the chemical formula of the lithium manganese iron phosphate positive electrode material is LiMn x Fe 1-x PO 4 , wherein the value of x is 0.2-0.7, and the molar ratio of the total doping amount of boron to the total phosphorus element is 2-3:97-98;
  • the maximum doping amount of boron is 1.5-2.0%, and the minimum doping amount is 0.008-0.02%.
  • the present invention provides a method for preparing the lithium iron manganese phosphate positive electrode material of the aforementioned embodiment, preparing a boron-doped lithium iron manganese phosphate compound, mixing the boron-doped lithium iron manganese phosphate compound with an iron source, a manganese source and a phosphorus source to form a core-shell type manganese iron phosphate, and sintering the core-shell type manganese iron phosphate with a lithium source and a carbon source.
  • a lithium iron manganese phosphate compound is prepared by a solvothermal reaction method using a lithium source, a phosphorus source, a boron source, an iron source, a manganese source, a reducing agent and a first solvent as raw materials.
  • the lithium source, phosphorus source, boron source, iron source and manganese source are sampled according to a stoichiometric ratio, mixed with a reducing agent and a first solvent to form a suspension, and then subjected to a solvothermal reaction at 160° C. to 200° C. for 2 h to 6 h;
  • the lithium source is first mixed with the first solvent and then mixed with the phosphorus source and the boron source to dissolve, and then the iron source and the manganese source are added to the mixed solution to form a suspension;
  • the reducing agent is selected from at least one of ascorbic acid and tartaric acid;
  • the first solvent is ethylene glycol
  • solid-liquid separation, washing and drying are carried out in sequence after the solvothermal reaction is completed.
  • the process of preparing the core-shell manganese iron phosphate includes: mixing the boron-doped manganese iron lithium phosphate compound with an iron source, a manganese source, a phosphorus source and a second solvent to perform a solvothermal reaction;
  • the temperature of the solvent thermal reaction is controlled to be 160°C-200°C, and the time of the solvent thermal reaction is 2h-6h;
  • the second solvent is water
  • the process for preparing core-shell ferromanganese phosphate further comprises: sequentially performing solid-liquid separation, washing and drying after the solvent thermal reaction.
  • the core-shell type manganese iron phosphate is mixed with a lithium source and a carbon source, and sintered at 550° C.-650° C.;
  • the heating rate is 8°C/min-12°C/min, and after the temperature is raised to the sintering temperature, the sintering time is controlled to be 4h-7h.
  • the carbon source is selected from at least one of glucose and sucrose
  • the ratio of the total mass of the core-shell type manganese iron phosphate and the lithium source to the mass of the carbon source is 100:4-6.
  • the iron source is selected from at least one of ferrous sulfate and ferrous nitrate;
  • the manganese source is selected from at least one of manganese sulfate and manganese nitrate;
  • the lithium source is at least one of lithium hydroxide and lithium carbonate;
  • the boron source is boric acid.
  • the present invention provides a lithium-ion battery, comprising the lithium iron manganese phosphate positive electrode material of any one of the aforementioned embodiments or the lithium iron manganese phosphate positive electrode material of any one of the aforementioned embodiments.
  • the present invention has the following beneficial effects: by doping boron into lithium manganese iron phosphate particles and decreasing the boron element from the inside to the outside along the core, the conductivity of the positive electrode material is also correspondingly reduced from the inside to the outside, thereby not causing a sudden change in current, reducing impedance, and effectively improving the electrochemical performance of lithium manganese iron phosphate.
  • the phosphorus can be effectively increased without affecting the gram capacity.
  • FIG1 is an XRD diagram of the materials prepared in Example 1 and Comparative Example 1;
  • FIG. 2 is a SEM image of the material prepared in Example 1.
  • the present invention provides a method for preparing a lithium manganese iron phosphate positive electrode material, comprising the following steps:
  • the method for preparing the boron-doped lithium manganese iron phosphate compound is not limited, and a solvent thermal reaction method may be used, but is not limited thereto.
  • a lithium iron manganese phosphate compound is prepared by a solvothermal reaction method using a lithium source, a phosphorus source, a boron source, an iron source, a manganese source, a reducing agent and a first solvent as raw materials.
  • the lithium source, the phosphorus source, the boron source, the iron source and the manganese source are sampled according to a stoichiometric ratio, and mixed with the reducing agent and the first solvent to form a suspension, and then the suspension is transferred to an autoclave for a solvothermal reaction at 160° C. to 200° C. for 2 h to 6 h.
  • the temperature of the solvothermal reaction can be 160°C, 170°C, 180°C, 190°C, 200°C, etc.
  • the solvothermal reaction time can be 2h, 3h, 4h, 5h, 6h, etc.
  • the lithium source, phosphorus source, boron source, iron source and manganese source are sampled according to a stoichiometric ratio, so that the chemical formula of the boron-doped lithium manganese iron phosphate compound synthesized is controlled to be LiMn x Fe 1-x PO 4 , wherein the value of x is 0.2-0.7 (such as LiMn 0.3 Fe 0.7 PO 4 anhydrous compound), and the molar ratio of the total doping amount of boron to the total phosphorus element is 2-3:97-98, such as 2:98, 3:97, etc.
  • the lithium source is first mixed with the first solvent and then mixed with the phosphorus source and the boron source to dissolve, and then the iron source and the manganese source are added to the mixed solution to form a dark green suspension.
  • the raw materials can be better mixed and uniform.
  • the reducing agent is selected from at least one of ascorbic acid and tartaric acid
  • the first solvent is ethylene glycol
  • the iron source is selected from at least one of ferrous sulfate and ferrous nitrate
  • the manganese source is selected from at least one of manganese sulfate and manganese nitrate
  • the lithium source is at least one of lithium hydroxide and lithium carbonate
  • the boron source is boric acid.
  • the lithium source, phosphorus source, boron source, iron source, manganese source, reducing agent and first solvent are The above reagents are all suitable for the reaction system in the embodiment of the present invention, and can prepare boron-doped lithium manganese iron phosphate compounds that meet the requirements.
  • solid-liquid separation, washing and drying are sequentially performed to obtain a solid intermediate product.
  • the solid-liquid separation method is not limited, and it can be centrifugation; washing can be a combination of water washing and alcohol washing, and the number of times is not limited to remove ionic impurities remaining on the surface; the drying temperature can be about 80°C, but is not limited thereto, and the drying time can be 10h-15h, such as 10h, 12h, 14h, 15h, etc.
  • the boron-doped lithium manganese iron phosphate compound is mixed with an iron source, a manganese source and a phosphorus source to form a core-shell type manganese iron phosphate.
  • this step of reaction can be carried out by a solvothermal reaction method, but is not limited thereto.
  • the process of preparing core-shell manganese iron phosphate includes: mixing a boron-doped manganese iron lithium phosphate compound with an iron source, a manganese source, a phosphorus source, and a second solvent to perform a solvothermal reaction; controlling the temperature of the solvothermal reaction to be 160°C-200°C, and the solvothermal reaction time to be 2h-6h.
  • the temperature of the solvothermal reaction can be 160°C, 170°C, 180°C, 190°C, 200°C, etc.
  • the solvothermal reaction time can be 2h, 3h, 4h, 5h, 6h, etc.
  • step S1 when preparing the core-shell manganese iron phosphate, the molar ratio of the iron source, manganese source and phosphorus source used is roughly the same as that in step S1, so that the chemical composition of the final manganese iron phosphate lithium product is uniform.
  • the types of the iron source, manganese source and phosphorus source also refer to step S1, and will not be repeated here.
  • solid-liquid separation is not limited, and it can be centrifugal; washing can be a combination of water washing and alcohol washing, and the number of times is not limited to remove ionic impurities remaining on the surface; the drying temperature can be about 80°C, but is not limited thereto, and the drying time can be 10h-15h, such as 10h, 12h, 14h, 15h, etc.
  • the second solvent is water.
  • the above embodiments are all suitable for use as a solvent in this step.
  • the core-shell type manganese iron phosphate is mixed with a lithium source for sintering, so that the manganese iron phosphate on the surface shell forms lithium manganese iron phosphate.
  • Boron oxide forms lithium borate, a fast ion conductor, with lithium, which accelerates the entry and insertion of lithium ions.
  • the conductivity of the positive electrode material is effectively improved; due to the low melting point of boron oxide, during the high-temperature calcination process, boron will migrate from the inside to the outside along the core, thereby forming lithium manganese iron phosphate with a decreasing boron content along the core from the inside to the outside.
  • the core-shell manganese ferrophosphate is mixed with a lithium source and a carbon source and sintered at 550°C-650°C.
  • the introduction of a carbon source and the formation of a carbon coating after sintering are beneficial to further improve the electrochemical properties of the material.
  • the sintering temperature can be 550°C, 580°C, 600°C, 620°C, 650°C, etc.
  • the molar ratio of the amount of the lithium source to the manganese iron phosphate coating layer formed in step S2 is 1:1.
  • the heating rate is controlled to be 8°C/min-12°C/min (such as 8°C/min, 10°C/min, 12°C/min, etc.), and after heating to the sintering temperature, the sintering time is controlled to be 4h-7h (such as 4h, 5h, 6h, 7h, etc.).
  • the carbon source is selected from at least one of glucose and sucrose, and can be any one or more of the above.
  • the ratio of the total mass of the core-shell manganese iron phosphate and the lithium source to the amount of the carbon source is 100:4-6, such as 100:4, 100:5, 100:6, etc.
  • An embodiment of the present invention provides a lithium iron manganese phosphate positive electrode material, including: lithium iron manganese phosphate particles, in which boron is doped, and the doping amount of boron gradually decreases from the inside to the outside of the lithium iron manganese phosphate particles.
  • the lithium iron manganese phosphate positive electrode material can be prepared by the above-mentioned preparation method.
  • the chemical formula of the lithium manganese iron phosphate positive electrode material is LiMn x Fe 1-x PO 4 , wherein the value of x is 0.2-0.7, and the molar ratio of the total amount of boron doping to the total phosphorus element is 2-3:97-98, such as LiMn 0.3 Fe 0.7 PO 4 anhydrous compound.
  • the maximum amount of boron doping is 1.5-2.0% (such as 1.5%, 2.0%, etc.), and the minimum amount of boron doping is 0.008-0.02% (such as 0.008%, 0.01%, 0.02%, etc.).
  • the maximum doping amount refers to the boron content in the innermost part of the material, which refers to the mass fraction of boron; the minimum doping amount refers to the boron content in the outermost part of the material, which refers to the mass fraction of boron.
  • the prepared lithium manganese iron phosphate positive electrode material can be further prepared into a lithium ion battery. Due to the improvement in the performance of the positive electrode material, it is beneficial to further improve the electrochemical performance of the lithium ion battery.
  • This embodiment provides a method for preparing a lithium manganese iron phosphate positive electrode material, comprising the following steps:
  • LiMn 0.3 Fe 0.7 PO 4 material was prepared by solvothermal method with lithium hydroxide, phosphoric acid, boric acid, iron source, manganese source, ascorbic acid and ethylene glycol as raw materials.
  • the obtained mixture was transferred to an autoclave and heated at 180°C.
  • the solvent thermal reaction was carried out for 4 h at 80°C, and then the pure boron-doped LiMn 0.3 Fe 0.7 PO 4 was generated after centrifugation, washing and drying at 80°C for 12 h.
  • the core-shell manganese iron phosphate particles and lithium hydroxide in step (2) are uniformly mixed in a molar ratio of 1:1 between the core-shell manganese iron phosphate particles and the lithium hydroxide, 4 wt % of glucose is added to the mixture, and the mixture is placed at 600° C.
  • the maximum boron doping amount is 1.6%
  • the minimum boron doping amount is 0.01%
  • the molar ratio of the total boron doping amount to the total phosphorus element in the final positive electrode material is 2:98.
  • This embodiment provides a method for preparing a lithium manganese iron phosphate positive electrode material, comprising the following steps:
  • Example 1 The only difference from Example 1 is that the amount of glucose added is 6 wt %, that is, the mass ratio of the total mass of the core-shell lithium manganese iron phosphate particles and lithium hydroxide to glucose is controlled to be 100:6.
  • This embodiment provides a method for preparing a lithium manganese iron phosphate positive electrode material, comprising the following steps:
  • LiMn 0.3 Fe 0.7 PO 4 material was prepared by solvothermal method with lithium hydroxide, phosphoric acid, boric acid, iron source, manganese source, ascorbic acid and ethylene glycol as raw materials.
  • the specific steps are the same as those in Example 1. At this time, in different regions from the inside to the outside of the lithium manganese iron phosphate particles, the maximum doping amount of boron is 2%, and the minimum doping amount is 0.01%.
  • Example 1 The only difference from Example 1 is that the molar ratio of P:B in step (1) is 94:6, and the molar ratio of the total amount of boron doping to the total phosphorus element in the finally obtained positive electrode material is 3:97.
  • This embodiment provides a method for preparing a lithium manganese iron phosphate positive electrode material, comprising the following steps:
  • LiMn 0.2 Fe 0.8 PO 4 material was prepared by solvothermal method with lithium hydroxide, phosphoric acid, boric acid, iron source, manganese source, ascorbic acid and ethylene glycol as raw materials.
  • step (1) Take 25 g of the boron-doped LiMn 0.2 Fe 0.8 PO 4 anhydrous compound prepared in step (1), mix it with 11.12 g of ferrous sulfate heptahydrate, 1.51 g of manganese sulfate, and 4.90 g of phosphoric acid (the molar ratio of Mn, Fe, and P is 0.2:0.8:1.0) in 100 mL of deionized water, stir well, and then transfer it to a hydrothermal reactor, carry out solvothermal reaction at 180°C for 4 h, and then centrifuge, wash, and dry at 80°C for 12 h.
  • phosphoric acid the molar ratio of Mn, Fe, and P is 0.2:0.8:1.0
  • the core-shell manganese iron phosphate particles and lithium hydroxide in step (2) are uniformly mixed in a molar ratio of 1:1 between the core-shell manganese iron phosphate particles and lithium hydroxide, 4 wt % of glucose is added to the mixture, and the mixture is placed at 600° C. for 5 h in a nitrogen atmosphere at a heating rate of 10° C./min, and then cooled to room temperature to obtain a boron gradient-doped lithium manganese iron phosphate positive electrode material.
  • This embodiment provides a method for preparing a lithium manganese iron phosphate positive electrode material, comprising the following steps:
  • LiMn 0.5 Fe 0.5 PO 4 material was prepared by solvothermal method with lithium hydroxide, phosphoric acid, boric acid, iron source, manganese source, ascorbic acid and ethylene glycol as raw materials.
  • the core-shell manganese iron phosphate particles and lithium hydroxide in step (2) are uniformly mixed in a molar ratio of 1:1 between the core-shell manganese iron phosphate particles and lithium hydroxide, 4 wt % of glucose is added to the mixture, and the mixture is placed at 600° C. for 5 h in a nitrogen atmosphere at a heating rate of 10° C./min, and then cooled to room temperature to obtain a boron gradient-doped lithium manganese iron phosphate positive electrode material.
  • This embodiment provides a method for preparing a lithium manganese iron phosphate positive electrode material, comprising the following steps:
  • LiMn 0.7 Fe 0.3 PO 4 material was prepared by solvothermal method with lithium hydroxide, phosphoric acid, boric acid, iron source, manganese source, ascorbic acid and ethylene glycol as raw materials.
  • the obtained mixture was transferred to an autoclave and heated at 180°C.
  • the solvent thermal reaction was carried out for 4 h at 80°C, and then the pure boron-doped LiMn 0.7 Fe 0.3 PO 4 was generated after centrifugation, washing and drying at 80°C for 12 h.
  • the core-shell manganese iron phosphate particles and lithium hydroxide in step (2) are uniformly mixed in a molar ratio of 1:1 between the core-shell manganese iron phosphate particles and lithium hydroxide, 4 wt % of glucose is added to the mixture, and the mixture is placed at 600° C. for 5 h in a nitrogen atmosphere at a heating rate of 10° C./min, and then cooled to room temperature to obtain a boron gradient-doped lithium manganese iron phosphate positive electrode material.
  • This comparative example provides a method for preparing lithium manganese iron phosphate LiMn 0.3 Fe 0.7 PO 4 , which is different from Example 1 in that it does not contain a boron source.
  • the specific process is as follows:
  • LiMn 0.3 Fe 0.7 PO 4 material was prepared by solvothermal method with lithium hydroxide, phosphoric acid, boric acid, iron source, manganese source, ascorbic acid and ethylene glycol as raw materials.
  • LiMn 0.3 Fe 0.7 PO 4 was generated after centrifugation, washing, and drying at 80°C for 12 h.
  • step (1) The lithium iron manganese phosphate particles and lithium hydroxide obtained in step (1) are uniformly mixed in a molar ratio of lithium iron manganese phosphate particles to lithium hydroxide of 1:1, 4 wt % of glucose is added to the mixture, and the mixture is placed at 600° C. for 5 h in a nitrogen atmosphere at a heating rate of 10° C./min, and then cooled to room temperature to obtain a lithium iron manganese phosphate positive electrode material.
  • This comparative example provides a method for preparing lithium manganese iron phosphate LiMn 0.3 Fe 0.7 PO 4 , and the specific process is as follows:
  • LiMn 0.3 Fe 0.7 PO 4 material LiMn 0.3 Fe 0.7 PO 4 material.
  • LiOH ⁇ 7H 2 O was added to ethylene glycol in a stoichiometric ratio and stirred for 20 min.
  • H 3 PO 4 was dissolved in the above solution under magnetic stirring in a stoichiometric ratio.
  • Ferrous nitrate and manganese nitrate were added to the solution to form a dark green suspension.
  • the obtained mixture was transferred to an autoclave and subjected to a solvothermal reaction at 180°C for 4 h. After centrifugation, washing and drying at 80°C for 12 h, pure LiMn 0.3 Fe 0.7 B 0.4 P 0.96 O 4 was generated.
  • step (1) (2) the lithium iron manganese phosphate particles and lithium hydroxide prepared in step (1) are uniformly mixed in a molar ratio of lithium iron manganese phosphate particles to lithium hydroxide of 1:1, 6 wt % of glucose is added to the mixture, and the mixture is placed at 600° C. for 5 h under a nitrogen atmosphere at a heating rate of 10° C./min, and then cooled to room temperature to obtain a lithium iron manganese phosphate positive electrode material;
  • the difference from Comparative Example 1 is that the amount of glucose added is 6 wt %, that is, the mass ratio of the total mass of the core-shell lithium manganese iron phosphate particles and lithium hydroxide to glucose is controlled to be 100:6.
  • This embodiment provides a method for preparing a lithium manganese iron phosphate positive electrode material, comprising the following steps:
  • LiMn 0.3 Fe 0.7 PO 4 material was prepared by solvothermal method with lithium hydroxide, phosphoric acid, boric acid, iron source, manganese source, ascorbic acid and ethylene glycol as raw materials.
  • the specific steps are the same as those in Example 1. At this time, in different regions from the inside to the outside of the lithium manganese iron phosphate particles, the maximum doping amount of boron is 1%, and the minimum doping amount is 0.01%.
  • Example 1 The only difference from Example 1 is that the molar ratio of P:B in step (1) is 98:2, and the molar ratio of the total amount of boron doping to the total phosphorus element in the finally obtained positive electrode material is 1:99.
  • This embodiment provides a method for preparing a lithium manganese iron phosphate positive electrode material, comprising the following steps:
  • LiMn 0.3 Fe 0.7 PO 4 material was prepared by solvothermal method with lithium hydroxide, phosphoric acid, boric acid, iron source, manganese source, ascorbic acid and ethylene glycol as raw materials.
  • the specific steps are the same as those in Example 1. At this time, in different regions from the inside to the outside of the lithium manganese iron phosphate particles, the maximum doping amount of boron is 2.5%, and the minimum doping amount is 0.01%.
  • Example 1 The only difference from Example 1 is that the molar ratio of P:B in step (1) is 92:8, and the molar ratio of the total amount of boron doping to the total phosphorus element in the finally obtained positive electrode material is 4:96.
  • This comparative example provides a method for preparing lithium manganese iron phosphate LiMn 0.3 Fe 0.7 PO 4 , and the specific process is as follows:
  • LiMn 0.3 Fe 0.7 PO 4 material was prepared by solvothermal method with lithium hydroxide, phosphoric acid, boric acid, iron source, manganese source, ascorbic acid and ethylene glycol as raw materials.
  • Preparation of positive electrode sheet The positive electrode material, conductive black and polyvinylidene fluoride prepared above were weighed and mixed with an appropriate amount of N-methylpyrrolidone in a mass ratio of 8:1:1; the mixed positive electrode material slurry was obtained after homogenization with an ultrafine homogenizer for 25 minutes; the positive electrode material slurry was evenly coated on aluminum foil (thickness of 170um) with an automatic coating and drying machine; the coated positive electrode material slurry was The aluminum foil is placed in a vacuum oven and dried for 10 hours; after being taken out, it is sliced to obtain positive electrode material plates, and then the plates are pressed using an electric tablet press.
  • Assembled battery With lithium metal sheet as counter electrode, polyethylene microporous membrane as separator, lithium hexafluorophosphate as electrolyte, the synthesized and pressed material electrode sheet as positive electrode sheet, the battery was assembled in a glove box filled with argon in the same way as CR2025 button battery assembly to complete the battery production. Then the electrochemical performance test was carried out at 25°C and 3.0-4.5V, and the results are shown in Table 1.
  • the charge transfer impedance (Rct) of the positive electrode material with gradient boron doping is lower than that of the positive electrode material without gradient boron doping. This is because the conductivity of the positive electrode material decreases from the inside to the outside as the boron content decreases from the inside to the outside, which does not cause a sudden change in the current, thereby effectively reducing the impedance; although Comparative Examples 3 and 4 are doped with boron, the charge transfer impedance is close to that of Comparative Example 1, indicating that excessive B doping and too little B doping cannot play a good role in reducing the material impedance; in addition, the charge transfer impedance of Comparative Example 5 is close to that of Comparative Example 1, which also shows that the conventional method of doping Impurity B also cannot play a role in reducing material impedance.
  • the gram capacity of Examples 1-3 is close to that of Comparative Examples 1 and 2, indicating that the gradient doping of the B source has no significant effect on the gram capacity of the positive electrode material; the discharge specific capacity of Examples 1-3 at 0.1C, 0.5C, and 1C is higher than that of Comparative Examples 1 and 2, because conductive holes and lone pairs of electrons are introduced by doping with a boron source, thereby effectively improving the conductivity of the positive electrode material; at the same time, boron oxide forms a fast ion conductor lithium borate with lithium, which accelerates the entry and insertion of lithium ions, thereby effectively improving the conductivity of the positive electrode material.
  • Comparative Example 4 The gram capacity of Comparative Example 4 is lower than that of Comparative Example 1, which is caused by excessive B doping; and excessive B doping will reduce the electrochemical performance of the material. However, too little B doping (Comparative Example 3) will not play a good role in improving the electrochemical performance of the material.
  • the SEM image of the material prepared in Test Example 1 is shown in FIG2 .
  • the prepared lithium manganese iron phosphate particles are between 100 and 150 nm.

Landscapes

  • Battery Electrode And Active Subsutance (AREA)

Abstract

本发明公开了一种磷酸锰铁锂正极材料、其制备方法及电池，涉及电池材料技术领域。通过在磷酸锰铁锂颗粒中掺杂硼，并使硼元素沿核由内到外递减，正极材料的导电性能也相应地由内到外梯次降低，从而不会导致电流骤然变化，降低了阻抗，有效提高了磷酸锰铁锂的电化学性能，可以在不影响克容量的前提下有效提高了磷酸锰铁锂正极材料的导电性能和电化学性能。

Description

一种磷酸锰铁锂正极材料、其制备方法及电池 技术领域
本发明涉及电池材料技术领域，具体而言，涉及一种磷酸锰铁锂正极材料、其制备方法及电池。
背景技术
随着电动汽车的应用推广，对动力锂离子电池材料的要求逐渐细分化，磷酸锰铁锂展现较高电压平台和高比能量密度而成为研究热点。虽然相比于磷酸铁锂和磷酸锰锂，磷酸锰铁锂的电压平台和电导率以及锂离子传导率有所改善，但单一的磷酸锰铁锂的导电性依然很差，纯磷酸锰铁锂几乎为绝缘体，很难使材料的电化学性能充分发挥出来。
目前，一般通过离子掺杂、导电相碳包覆、颗粒尺寸纳米化及形貌控制提高磷酸锰铁锂的电化学性能，但是导电剂和碳包覆层过多会降低正极材料的克容量，导致倍率性能和循环性能下降。因此，亟需研究出在不影响克容量的前提下，改善磷酸锰铁锂导电性和电化学性能的方法。
鉴于此，特提出本发明。
发明内容
本发明的目的在于提供一种磷酸锰铁锂正极材料、其制备方法及电池，旨在不影响克容量的前提下改善磷酸锰铁锂的导电性和电化学性能。
本发明是这样实现的：
第一方面，本发明提供一种磷酸锰铁锂正极材料，包括：磷酸锰铁锂颗粒，在磷酸锰铁锂颗粒中掺杂有硼，且硼的掺杂量从磷酸锰铁锂颗粒的内部至外部逐渐减少。
在可选的实施方式中，磷酸锰铁锂正极材料的化学式为LiMnxFe1-xPO4，其中，x的取值为0.2-0.7，硼的总掺杂量与总磷元素的摩尔比为2～3:97～98；
优选地，在磷酸锰铁锂颗粒从内至外的不同区域中，硼的最大掺杂量为1.5-2.0％，最小掺杂量为0.008-0.02％。
第二方面，本发明提供一种前述实施方式的磷酸锰铁锂正极材料的制备方法，制备硼掺杂的磷酸锰铁锂化合物，将硼掺杂的磷酸锰铁锂化合物与铁源、锰源和磷源混合制备形成核壳型磷酸锰铁，利用核壳型磷酸锰铁与锂源和碳源混合烧结。
在可选的实施方式中，以锂源、磷源、硼源、铁源、锰源、还原剂和第一溶剂为原料，采用溶剂热反应的方法制备磷酸锰铁锂化合物。
在可选的实施方式中，将锂源、磷源、硼源、铁源和锰源按照化学计量比取样，并与还原剂和第一溶剂混合形成悬浮液，然后在160℃-200℃的条件下进行溶剂热反应2h-6h；
优选地，先将锂源与第一溶剂混合之后再与磷源和硼源混合溶解，然后在混合溶液中加入铁源和锰源形成悬浮液；
优选地，还原剂选自抗坏血酸和酒石酸中的至少一种；
优选地，第一溶剂为乙二醇；
优选地，在溶剂热反应完成后依次进行固液分离、洗涤和干燥。
在可选的实施方式中，制备核壳型磷酸锰铁的过程包括：将硼掺杂的磷酸锰铁锂化合物与铁源、锰源、磷源和第二溶剂混合，进行溶剂热反应；
优选地，在制备核壳型磷酸锰铁时，控制溶剂热反应的温度为160℃-200℃，溶剂热反应的时间为2h-6h；
优选地，第二溶剂为水；
优选地，制备核壳型磷酸锰铁的过程还包括：在溶剂热反应之后依次进行固液分离、洗涤和干燥。
在可选的实施方式中，将核壳型磷酸锰铁与锂源和碳源混合，在550℃-650℃的条件下进行烧结；
优选地，升温速率为8℃/min-12℃/min，升温至烧结温度后控制烧结时间为4h-7h。
在可选的实施方式中，碳源选自葡萄糖和蔗糖中的至少一种；
优选地，核壳型磷酸锰铁与锂源的总质量与碳源的质量之比为100:4-6。
在可选的实施方式中，铁源选自硫酸亚铁和硝酸亚铁中的至少一种；
优选地，锰源选自硫酸锰和硝酸锰中的至少一种；
优选地，锂源为氢氧化锂和碳酸锂中的至少一种；
优选地，硼源为硼酸。
第三方面，本发明提供一种锂离子电池，包括前述实施方式中任一项的磷酸锰铁锂正极材料或前述实施方式中任一项的磷酸锰铁锂正极材料。
本发明具有以下有益效果：通过在磷酸锰铁锂颗粒中掺杂硼，并使硼元素沿核由内到外递减，正极材料的导电性能也相应地由内到外梯次降低，从而不会导致电流骤然变化，降低了阻抗，有效提高了磷酸锰铁锂的电化学性能，可以在不影响克容量的前提下有效提高了磷 酸锰铁锂正极材料的导电性能和电化学性能。
附图说明
为了更清楚地说明本发明实施例的技术方案，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发明的某些实施例，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为实施例1和对比例1制备得到材料的XRD图；
图2为实施例1中制备得到材料的SEM图。
具体实施方式
为使本发明实施例的目的、技术方案和优点更加清楚，下面将对本发明实施例中的技术方案进行清楚、完整地描述。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。
本发明提供一种磷酸锰铁锂正极材料的制备方法，包括以下步骤：
S1、制备硼掺杂的磷酸锰铁锂化合物
制备硼掺杂的磷酸锰铁锂化合物的方法不限，可以采用溶剂热反应的方法，但不限于此。
在一些实施例中，以锂源、磷源、硼源、铁源、锰源、还原剂和第一溶剂为原料，采用溶剂热反应的方法制备磷酸锰铁锂化合物。在实际操作过程中，将锂源、磷源、硼源、铁源和锰源按照化学计量比取样，并与还原剂和第一溶剂混合形成悬浮液，然后将悬浮液转移至高压釜中在160℃-200℃的条件下进行溶剂热反应2h-6h。
具体地，溶剂热反应的温度可以为160℃、170℃、180℃、190℃、200℃等，溶剂热反应时间可以为2h、3h、4h、5h、6h等。
在一些实施例中，锂源、磷源、硼源、铁源和锰源按照化学计量比取样，使控制合成的硼掺杂的磷酸锰铁锂化合物的化学式为LiMnxFe1-xPO4，其中，x的取值为0.2-0.7(如可以为LiMn0.3Fe0.7PO4无水化合物)，硼的总掺杂量与总磷元素的摩尔比为2～3:97～98，如2:98、3:97等。
在一些实施例中，先将锂源与第一溶剂混合之后再与磷源和硼源混合溶解，然后在混合溶液中加入铁源和锰源形成墨绿色悬浮液。通过控制混料的步骤，以使原料更好地混合均匀。
进一步地，还原剂选自抗坏血酸和酒石酸中的至少一种，第一溶剂为乙二醇；铁源选自硫酸亚铁和硝酸亚铁中的至少一种；锰源选自硫酸锰和硝酸锰中的至少一种；锂源为氢氧化锂和碳酸锂中的至少一种；硼源为硼酸。锂源、磷源、硼源、铁源、锰源、还原剂和第一溶 剂选择以上几种，均适合于本发明实施例中的反应体系，能够制备得到满足要求的硼掺杂的磷酸锰铁锂化合物。
在一些实施例中，在溶剂热反应完成后依次进行固液分离、洗涤和干燥，以得到固体中间产品。固液分离的方式不限，可以为离心；洗涤可以采用水洗和醇洗结合的方式，次数不限，以将表面残留的离子杂质去除；干燥的温度可以为80℃左右，但不限于此，干燥时间可以为10h-15h，如10h、12h、14h、15h等。
S2、制备核壳型磷酸锰铁
将硼掺杂的磷酸锰铁锂化合物与铁源、锰源和磷源混合制备形成核壳型磷酸锰铁，同样这一步反应可以采用溶剂热反应的方法，但不限于此。
在一些实施例中，制备核壳型磷酸锰铁的过程包括：将硼掺杂的磷酸锰铁锂化合物与铁源、锰源、磷源和第二溶剂混合，进行溶剂热反应；控制溶剂热反应的温度为160℃-200℃，溶剂热反应的时间为2h-6h。具体地，溶剂热反应的温度可以为160℃、170℃、180℃、190℃、200℃等，溶剂热反应时间可以为2h、3h、4h、5h、6h等。
需要说明的是，制备核壳型磷酸锰铁时，所利用的铁源、锰源和磷源的摩尔比大致与步骤S1相同，使最终得到的磷酸铁锰锂产品的化学组成均一。铁源、锰源和磷源的种类也参照步骤S1，在此不做重复赘述。
同样，在溶剂热反应之后依次进行固液分离、洗涤和干燥，以得到固体中间产品。固液分离的方式不限，可以为离心；洗涤可以采用水洗和醇洗结合的方式，次数不限，以将表面残留的离子杂质去除；干燥的温度可以为80℃左右，但不限于此，干燥时间可以为10h-15h，如10h、12h、14h、15h等。
在一些实施例中，第二溶剂为水，以上实施例均适合于在该步骤中作为溶剂使用。
S3、制备硼梯度掺杂的磷酸锰铁锂
利用核壳型磷酸锰铁与锂源混合烧结，以使表面壳层的磷酸锰铁形成磷酸锰铁锂。氧化硼跟锂形成快离子导体硼酸锂，加快了锂离子的进入和嵌出。有效提高了正极材料的导电性能；由于硼的氧化物熔点较低，在高温煅烧的过程中，硼会沿核由内向外迁移，从而形成硼含量沿核由内到外递减的磷酸锰铁锂。通过掺杂硼源，引入了导电空穴与孤对电子，有效提高了正极材料的导电性能。因为硼的含量从颗粒内部到外部梯度递减，所以正极材料的导电性能也从内到外梯次降低，从而不会导致电流骤然变化，降低了阻抗，有效提高了磷酸锰铁锂的电化学性能。
在一些实施例中，将核壳型磷酸锰铁与锂源和碳源混合，在550℃-650℃的条件下进行烧 结，通过引入碳源烧结之后形成碳包覆有利于进一步提高材料的电化学性能。具体地，烧结温度可以为550℃、580℃、600℃、620℃、650℃等。锂源的用量与步骤S2中形成的磷酸锰铁包覆层的摩尔比为1:1。
在一些实施例中，烧结过程中，控制升温速率为8℃/min-12℃/min(如8℃/min、10℃/min、12℃/min等)，升温至烧结温度后控制烧结时间为4h-7h(如4h、5h、6h、7h等)。
在一些实施例中，碳源选自葡萄糖和蔗糖中的至少一种，可以为以上任意一种或几种。核壳型磷酸锰铁与锂源的总质量与碳源的用量之比为100:4-6，如可以为100:4、100:5、100:6等。
本发明实施例提供一种磷酸锰铁锂正极材料，包括：磷酸锰铁锂颗粒，在磷酸锰铁锂颗粒中掺杂有硼，且硼的掺杂量从磷酸锰铁锂颗粒的内部至外部逐渐减少，该磷酸锰铁锂正极材料可以通过上述制备方法制备而得。
进一步地，磷酸锰铁锂正极材料的化学式为LiMnxFe1-xPO4，其中，x的取值为0.2-0.7，硼的总掺杂量与总磷元素的摩尔比为2～3:97～98，如可以为LiMn0.3Fe0.7PO4无水化合物。在磷酸锰铁锂颗粒从内至外的不同区域中，硼的最大掺杂量为1.5-2.0％(如1.5％、2.0％等)，最小掺杂量为0.008-0.02％(如0.008％、0.01％、0.02％等)。
需要说明的是，最大掺杂量是材料最内部的硼含量，是指硼的质量分数；最小掺杂量是指材料最外部的硼含量，是指硼的质量分数。
在一些实施例中，可以将制备得到的磷酸锰铁锂正极材料进一步制备得到锂离子电池，由于正极材料性能的提升，有利于进一步改善锂离子电池的电化学性能。
以下结合实施例对本发明的特征和性能作进一步的详细描述。
实施例1
本实施例提供一种磷酸锰铁锂正极材料的制备方法，包括以下步骤：
(1)制备硼掺杂的LiMn0.3Fe0.7PO4
以氢氧化锂、磷酸、硼酸、铁源、锰源、抗坏血酸和乙二醇为原料，采用溶剂热法制备LiMn0.3Fe0.7PO4材料。
首先，按化学计量比将7.50g七水氢氧化锂(LiOH·7H2O)加入到80mL乙二醇中，搅拌20min。然后按化学计量比将4.90g磷酸(H3PO4)和0.13g硼酸(H3BO3)(P:B的摩尔比为＝96:4)在磁搅拌下溶解到上述溶液中。在溶液中加入9.73g七水合硫酸亚铁和2.27g硫酸锰(Mn:Fe＝0.3:0.7)，形成墨绿色悬浮液。最后，将得到的混合物转移到高压釜中，在180℃ 下进行溶剂热反应4h。在80℃下离心、洗涤、干燥12h后生成纯净的硼掺杂LiMn0.3Fe0.7PO4。
(2)制备核壳型磷酸锰铁
取步骤(1)中制得20g硼掺杂LiMn0.3Fe0.7PO4无水化合物与9.73g七水合硫酸亚铁、2.27g硫酸锰、4.90g磷酸(Mn、Fe、P摩尔比为0.3:0.7:1.0)混合在100mL去离子水中，搅拌均匀后转移至水热反应釜中，在180℃下进行溶剂热反应4h，然后在80℃下离心、洗涤、干燥12h。
(3)制备硼梯度掺杂的磷酸锰铁锂
将步骤(2)核壳型磷酸锰铁颗粒和氢氧化锂，按照核壳型磷酸锰铁粒子和氢氧化锂摩尔比为1:1的比例均匀混合，在混合物中加入4wt％的葡萄糖，在氮气气氛下，置于600℃中保温5h，升温速率为10℃/min，然后冷却至室温，即得到具有硼梯度掺杂的磷酸锰铁锂正极材料；此时，在磷酸锰铁锂颗粒从内至外的不同区域中，硼的最大掺杂量为1.6％，最小掺杂量为0.01％，最终得到的正极材料中硼的总掺杂量与总磷元素的摩尔比为2:98。
实施例2
本实施例提供一种磷酸锰铁锂正极材料的制备方法，包括以下步骤：
(1)制备硼掺杂的LiMn0.3Fe0.7PO4
具体步骤与实施例1相同。
(2)制备核壳型磷酸锰铁
具体步骤与实施例1相同。
(3)制备硼梯度掺杂的磷酸锰铁锂
与实施例1的区别仅在于：葡萄糖加入量为6wt％，即控制核壳型磷酸锰铁锂粒子和氢氧化锂总质量与葡萄糖的质量比为100:6。
实施例3
本实施例提供一种磷酸锰铁锂正极材料的制备方法，包括以下步骤：
(1)制备硼掺杂的LiMn0.3Fe0.7PO4
以氢氧化锂、磷酸、硼酸、铁源、锰源、抗坏血酸和乙二醇为原料，采用溶剂热法制备LiMn0.3Fe0.7PO4材料。
首先，按化学计量比将7.50g七水氢氧化锂(LiOH·7H2O)加入到80mL乙二醇中，搅拌20min。然后按化学计量比将4.90g磷酸(H3PO4)和0.20g硼酸(H3BO3)(P:B的摩尔比为＝94:6)在磁搅拌下溶解到上述溶液中。在溶液中加入9.73g七水合硫酸亚铁和2.27g硫酸锰 (Mn:Fe＝0.3:0.7)，形成墨绿色悬浮液。最后，将得到的混合物转移到高压釜中，在180℃下进行溶剂热反应4h。在80℃下离心、洗涤、干燥12h后生成纯净的硼掺杂LiMn0.3Fe0.7PO4。
(2)制备核壳型磷酸锰铁
具体步骤与实施例1相同。
(3)制备硼梯度掺杂的磷酸锰铁锂
具体步骤与实施例1相同。此时，在磷酸锰铁锂颗粒从内至外的不同区域中，硼的最大掺杂量为2％，最小掺杂量为0.01％。
与实施例1的区别仅在于：步骤(1)中P:B的摩尔比为＝94:6，最终得到的正极材料中硼的总掺杂量与总磷元素的摩尔比为3:97。
实施例4
本实施例提供一种磷酸锰铁锂正极材料的制备方法，包括以下步骤：
(1)制备硼掺杂的LiMn0.2Fe0.8PO4
以氢氧化锂、磷酸、硼酸、铁源、锰源、抗坏血酸和乙二醇为原料，采用溶剂热法制备LiMn0.2Fe0.8PO4材料。
首先，按化学计量比将7.50g七水氢氧化锂(LiOH·7H2O)加入到80mL乙二醇中，搅拌20min。然后按化学计量比将4.90g磷酸(H3PO4)和0.13g硼酸(H3BO3)(P:B的摩尔比为＝96:4)在磁搅拌下溶解到上述溶液中。在溶液中加入11.12g七水合硫酸亚铁和1.51g硫酸锰(Mn:Fe＝0.2:0.8)，形成墨绿色悬浮液。最后，将得到的混合物转移到高压釜中，在180℃下进行溶剂热反应4h。在80℃下离心、洗涤、干燥12h后生成纯净的硼掺杂LiMn0.2Fe0.8PO4。
(2)制备核壳型磷酸锰铁
取步骤(1)中制得25g硼掺杂LiMn0.2Fe0.8PO4无水化合物与11.12g七水合硫酸亚铁、1.51g硫酸锰、4.90g磷酸(Mn、Fe、P摩尔比为0.2:0.8：1.0)混合在100mL去离子水中，搅拌均匀后转移至水热反应釜中，在180℃下进行溶剂热反应4h，然后在80℃下离心、洗涤、干燥12h。
(3)制备硼梯度掺杂的磷酸锰铁锂
将步骤(2)核壳型磷酸锰铁颗粒和氢氧化锂，按照核壳型磷酸锰铁粒子和氢氧化锂摩尔比为1:1的比例均匀混合，在混合物中加入4wt％的葡萄糖，在氮气气氛下，置于600℃中保温5h，升温速率为10℃/min，然后冷却至室温，即得到具有硼梯度掺杂的磷酸锰铁锂正极材料。
实施例5
本实施例提供一种磷酸锰铁锂正极材料的制备方法，包括以下步骤：
(1)制备硼掺杂的LiMn0.5Fe0.5PO4
以氢氧化锂、磷酸、硼酸、铁源、锰源、抗坏血酸和乙二醇为原料，采用溶剂热法制备LiMn0.5Fe0.5PO4材料。
首先，按化学计量比将7.50g七水氢氧化锂(LiOH·7H2O)加入到80mL乙二醇中，搅拌20min。然后按化学计量比将4.90g磷酸(H3PO4)和0.13g硼酸(H3BO3)(P:B的摩尔比为＝96:4)在磁搅拌下溶解到上述溶液中。在溶液中加入6.95g七水合硫酸亚铁和3.78g硫酸锰(Mn:Fe＝0.5:0.5)，形成墨绿色悬浮液。最后，将得到的混合物转移到高压釜中，在180℃下进行溶剂热反应4h。在80℃下离心、洗涤、干燥12h后生成纯净的硼掺杂LiMn0.5Fe0.5PO4。
(2)制备核壳型磷酸锰铁
取步骤(1)中制得20g硼掺杂LiMn0.5Fe0.5PO4无水化合物与6.95g七水合硫酸亚铁、3.78g硫酸锰、4.90g磷酸(Mn、Fe、P摩尔比为0.5:0.5：1.0)混合在100mL去离子水中，搅拌均匀后转移至水热反应釜中，在180℃下进行溶剂热反应4h，然后在80℃下离心、洗涤、干燥12h。
(3)制备硼梯度掺杂的磷酸锰铁锂
将步骤(2)核壳型磷酸锰铁颗粒和氢氧化锂，按照核壳型磷酸锰铁粒子和氢氧化锂摩尔比为1:1的比例均匀混合，在混合物中加入4wt％的葡萄糖，在氮气气氛下，置于600℃中保温5h，升温速率为10℃/min，然后冷却至室温，即得到具有硼梯度掺杂的磷酸锰铁锂正极材料。
实施例6
本实施例提供一种磷酸锰铁锂正极材料的制备方法，包括以下步骤：
(1)制备硼掺杂的LiMn0.7Fe0.3PO4
以氢氧化锂、磷酸、硼酸、铁源、锰源、抗坏血酸和乙二醇为原料，采用溶剂热法制备LiMn0.7Fe0.3PO4材料。
首先，按化学计量比将7.50g七水氢氧化锂(LiOH·7H2O)加入到80mL乙二醇中，搅拌20min。然后按化学计量比将4.90g磷酸(H3PO4)和0.13g硼酸(H3BO3)(P:B的摩尔比为＝96:4)在磁搅拌下溶解到上述溶液中。在溶液中加入4.17g七水合硫酸亚铁和5.23g硫酸锰(Mn:Fe＝0.7:0.3)，形成墨绿色悬浮液。最后，将得到的混合物转移到高压釜中，在180℃ 下进行溶剂热反应4h。在80℃下离心、洗涤、干燥12h后生成纯净的硼掺杂LiMn0.7Fe0.3PO4。
(2)制备核壳型磷酸锰铁
取步骤(1)中制得20g硼掺杂LiMn0.7Fe0.3PO4无水化合物与4.17g七水合硫酸亚铁、5.23g硫酸锰、4.90g磷酸(Mn、Fe、P摩尔比为0.7:0.3：1.0)混合在100mL去离子水中，搅拌均匀后转移至水热反应釜中，在180℃下进行溶剂热反应4h，然后在80℃下离心、洗涤、干燥12h。
(3)制备硼梯度掺杂的磷酸锰铁锂
将步骤(2)核壳型磷酸锰铁颗粒和氢氧化锂，按照核壳型磷酸锰铁粒子和氢氧化锂摩尔比为1:1的比例均匀混合，在混合物中加入4wt％的葡萄糖，在氮气气氛下，置于600℃中保温5h，升温速率为10℃/min，然后冷却至室温，即得到具有硼梯度掺杂的磷酸锰铁锂正极材料。
对比例1
本对比例提供一种磷酸锰铁锂LiMn0.3Fe0.7PO4的制备方法，与实施例1的区别在于，不含硼源，具体过程为：
(1)制备LiMn0.3Fe0.7PO4
以氢氧化锂、磷酸、硼酸、铁源、锰源、抗坏血酸和乙二醇为原料，采用溶剂热法制备LiMn0.3Fe0.7PO4材料。
首先，按化学计量比将7.50g七水氢氧化锂(LiOH·7H2O)加入到80mL乙二醇中，搅拌20min。然后按化学计量比将4.90g磷酸(H3PO4)在磁搅拌下溶解到上述溶液中。在溶液中加入9.73g七水合硫酸亚铁和2.27g硫酸锰(Mn:Fe＝0.3:0.7)，形成墨绿色悬浮液。最后，将得到的混合物转移到高压釜中，在180℃下进行溶剂热反应4h。在80℃下离心、洗涤、干燥12h后生成纯净的LiMn0.3Fe0.7PO4。
(2)将步骤(1)制得的磷酸锰铁锂颗粒和氢氧化锂，按照磷酸锰铁锂粒子和氢氧化锂摩尔比为1:1的比例均匀混合，在混合物中加入4wt％的葡萄糖，在氮气气氛下，置于600℃中保温5h，升温速率为10℃/min，然后冷却至室温，即得到具有磷酸锰铁锂正极材料。
对比例2
本对比例提供一种磷酸锰铁锂LiMn0.3Fe0.7PO4的制备方法，具体过程为：
(1)制备LiMn0.3Fe0.7PO4
以氢氧化锂、磷酸、铁源、锰源、抗坏血酸和乙二醇为原料，采用溶剂热法制备 LiMn0.3Fe0.7PO4材料。
首先，按化学计量比将LiOH·7H2O加入到乙二醇中，搅拌20min。然后按化学计量比将H3PO4在磁搅拌下溶解到上述溶液中。在溶液中加入硝酸亚铁和硝酸锰，形成墨绿色悬浮液。最后，将得到的混合物转移到高压釜中，在180℃下进行溶剂热反应4h。在80℃下离心、洗涤、干燥12h后生成纯净的LiMn0.3Fe0.7B0.4P0.96O4。
(2)将步骤(1)制得的磷酸锰铁锂颗粒和氢氧化锂，按照磷酸锰铁锂粒子和氢氧化锂摩尔比为1:1的比例均匀混合，在混合物中加入6wt％的葡萄糖，在氮气气氛下，置于600℃中保温5h，升温速率为10℃/min，然后冷却至室温，即得到具有磷酸锰铁锂正极材料；
与对比例1的区别在于：葡萄糖加入量为6wt％，即控制核壳型磷酸锰铁锂粒子和氢氧化锂总质量与葡萄糖的质量比为100:6。
对比例3
本实施例提供一种磷酸锰铁锂正极材料的制备方法，包括以下步骤：
(1)制备硼掺杂的LiMn0.3Fe0.7PO4
以氢氧化锂、磷酸、硼酸、铁源、锰源、抗坏血酸和乙二醇为原料，采用溶剂热法制备LiMn0.3Fe0.7PO4材料。
首先，按化学计量比将7.50g七水氢氧化锂(LiOH·7H2O)加入到80mL乙二醇中，搅拌20min。然后按化学计量比将4.90g磷酸(H3PO4)和0.06g硼酸(H3BO3)(P:B的摩尔比为＝98:2)在磁搅拌下溶解到上述溶液中。在溶液中加入9.73g硫酸亚铁和2.27g硫酸锰(Mn:Fe＝0.3:0.7)，形成墨绿色悬浮液。最后，将得到的混合物转移到高压釜中，在180℃下进行溶剂热反应4h。在80℃下离心、洗涤、干燥12h后生成纯净的硼掺杂LiMn0.3Fe0.7PO4。
(2)制备核壳型磷酸锰铁
具体步骤与实施例1相同。
(3)制备硼梯度掺杂的磷酸锰铁锂
具体步骤与实施例1相同。此时，在磷酸锰铁锂颗粒从内至外的不同区域中，硼的最大掺杂量为1％，最小掺杂量为0.01％。
与实施例1的区别仅在于：步骤(1)中P:B的摩尔比为＝98:2，最终得到的正极材料中硼的总掺杂量与总磷元素的摩尔比为1:99。
对比例4
本实施例提供一种磷酸锰铁锂正极材料的制备方法，包括以下步骤：
(1)制备硼掺杂的LiMn0.3Fe0.7PO4
以氢氧化锂、磷酸、硼酸、铁源、锰源、抗坏血酸和乙二醇为原料，采用溶剂热法制备LiMn0.3Fe0.7PO4材料。
首先，按化学计量比将7.50g七水氢氧化锂(LiOH·7H2O)加入到80mL乙二醇中，搅拌20min。然后按化学计量比将4.90g磷酸(H3PO4)和0.27g硼酸(H3BO3)(P:B的摩尔比为＝92:8)在磁搅拌下溶解到上述溶液中。在溶液中加入9.73g硫酸亚铁和2.27g硫酸锰(Mn:Fe＝0.3:0.7)，形成墨绿色悬浮液。最后，将得到的混合物转移到高压釜中，在180℃下进行溶剂热反应4h。在80℃下离心、洗涤、干燥12h后生成纯净的硼掺杂LiMn0.3Fe0.7PO4。
(2)制备核壳型磷酸锰铁
具体步骤与实施例1相同。
(3)制备硼梯度掺杂的磷酸锰铁锂
具体步骤与实施例1相同。此时，在磷酸锰铁锂颗粒从内至外的不同区域中，硼的最大掺杂量为2.5％，最小掺杂量为0.01％。
与实施例1的区别仅在于：步骤(1)中P:B的摩尔比为＝92:8，最终得到的正极材料中硼的总掺杂量与总磷元素的摩尔比为4:96。
对比例5
本对比例提供一种磷酸锰铁锂LiMn0.3Fe0.7PO4的制备方法，具体过程为：
(1)制备硼掺杂的LiMn0.3Fe0.7PO4
以氢氧化锂、磷酸、硼酸、铁源、锰源、抗坏血酸和乙二醇为原料，采用溶剂热法制备LiMn0.3Fe0.7PO4材料。
按化学计量比将7.5g七水氢氧化锂(LiOH·7H2O)、4.90g磷酸(H3PO4)、0.14g三氧化二硼(B2O3)(P:B的摩尔比为＝96:4)、9.73g七水合硫酸亚铁、2.27g硫酸锰(Mn:Fe＝0.3:0.7)和4wt％的葡萄糖的混合均匀，加入10mL乙醇，在300r/min的转速下球磨7h，将球磨后的原料在氮气气氛保护下升温至650℃下煅烧得到硼掺杂的LiMn0.3Fe0.7PO4。
试验例
采用上述实施例和对比例提供的磷酸锰铁锂正极材料颗粒，按如下方法组装电池：
正极片的制备：按照8:1:1的质量比分别称取上述制得的正极材料、导电黑、聚偏氟乙烯并与适量的N-甲基吡咯烷酮进行混合；用超细匀浆机匀浆25min后得到混合后正极材料浆料；再用自动涂布烘干机将正极材料浆料均匀涂布在铝箔上(厚度为170um)；涂布后的 铝箔放入真空烘箱中烘干10h；取出后经过切片得正极材料极片，再用电动压片机对极片进行压片。
组装电池：以金属锂片为对电极，聚乙烯微孔膜为隔膜，六氟磷锂为电解液，所合成并且进行压片后的材料电极片为正极片按照CR2025型纽扣电池装配的方式在充满氩气的手套箱中进行组装，完成电池制作。然后在25℃下3.0-4.5V进行电化学性能测试，结果如表1所示。
表1实施例和对比例得到正极材料的性能测试结果
由实施例1-3可以看出，梯度掺杂硼的正极材料比没有梯度掺杂硼的正极材料的电荷转移阻抗(Rct)低，这是因为正极材料的导电性能随着硼含量由内到外递减而从内到外梯次降低，不会引起电流的骤然变化，从而有效降低了阻抗；对比例3和对比例4虽然掺杂了硼，但是电荷转移阻抗与对比例1接近，说明B掺杂量过多和B掺杂量过少，不能起到很好降低材料阻抗的作用；此外，对比例5和对比例1电荷转移阻抗接近，这也说明了用常规方法掺 杂B也无法起到降低材料阻抗的作用。
此外，实施例1-3的克容量与对比例1和对比例2接近，说明了梯度掺杂B源对正极材料的克容量并没有显著的影响；实施例1-3在0.1C、0.5C、1C下的放电比容量比对比例1和对比例2高，是因为通过掺杂硼源，引入了导电空穴与孤对电子，有效提高了正极材料的导电性能；同时，氧化硼跟锂形成快离子导体硼酸锂，加快了锂离子的进入和嵌出，有效提高了正极材料的导电性能。
对比例4的克容量低于对比例1，这是由B掺杂量过多导致的；且B掺杂量过多，会降低材料的电化学性能。而B掺杂量过少(对比例3)，则起不到很好提高材料电化学性能的作用。
试验例2
测试实施例1和对比例1制备得到材料的XRD图，结果如图1所示。
可见，由于B的加入，磷酸锰铁锂29.9°处的峰向更高的角度移动，移动至29.5°，这是由于B成功掺杂在了磷酸锰铁锂的P位导致的。
测试实施例1制备得到材料的SEM图，结果如图2所示。
可见，制备得到的磷酸锰铁锂颗粒在100～150nm。
以上仅为本发明的优选实施例而已，并不用于限制本发明，对于本领域的技术人员来说，本发明可以有各种更改和变化。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (10)

  1. 一种磷酸锰铁锂正极材料，其特征在于，包括：磷酸锰铁锂颗粒，在所述磷酸锰铁锂颗粒中掺杂有硼，且硼的掺杂量从所述磷酸锰铁锂颗粒的内部至外部逐渐减少。
  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，磷酸锰铁锂正极材料的化学式为LiMnxFe1-xPO4，其中，x的取值为0.2-0.7，硼的总掺杂量与总磷元素的摩尔比为2～3:97～98；
    优选地，在所述磷酸锰铁锂颗粒从内至外的不同区域中，硼的最大掺杂量为1.5-2.0％，最小掺杂量为0.008-0.02％。
  3. 一种权利要求1或2所述的磷酸锰铁锂正极材料的制备方法，其特征在于，制备硼掺杂的磷酸锰铁锂化合物，将所述硼掺杂的磷酸锰铁锂化合物与铁源、锰源和磷源混合制备形成核壳型磷酸锰铁，利用所述核壳型磷酸锰铁与锂源和碳源混合烧结。
  4. 根据权利要求3所述的制备方法，其特征在于，以锂源、磷源、硼源、铁源、锰源、还原剂和第一溶剂为原料，采用溶剂热反应的方法制备所述磷酸锰铁锂化合物。
  5. 根据权利要求4所述的制备方法，其特征在于，将所述锂源、所述磷源、所述硼源、所述铁源和所述锰源按照化学计量比取样，并与还原剂和第一溶剂混合形成悬浮液，然后在160℃-200℃的条件下进行溶剂热反应2h-6h；
    优选地，先将所述锂源与所述第一溶剂混合之后再与所述磷源和所述硼源混合溶解，然后在混合溶液中加入所述铁源和所述锰源形成悬浮液；
    优选地，所述还原剂选自抗坏血酸和酒石酸中的至少一种；
    优选地，所述第一溶剂为乙二醇；
    优选地，在溶剂热反应完成后依次进行固液分离、洗涤和干燥。
  6. 根据权利要求3所述的制备方法，其特征在于，制备所述核壳型磷酸锰铁的过程包括：将所述硼掺杂的磷酸锰铁锂化合物与所述铁源、所述锰源、所述磷源和第二溶剂混合，进行溶剂热反应；
    优选地，在制备所述核壳型磷酸锰铁时，控制溶剂热反应的温度为160℃-200℃，溶剂热反应的时间为2h-6h；
    优选地，所述第二溶剂为水；
    优选地，制备所述核壳型磷酸锰铁的过程还包括：在溶剂热反应之后依次进行固液分离、洗涤和干燥。
  7. 根据权利要求3所述的制备方法，其特征在于，将所述核壳型磷酸锰铁与所述锂源和碳源混合，在550℃-650℃的条件下进行烧结；
    优选地，升温速率为8℃/min-12℃/min，升温至烧结温度后控制烧结时间为4h-7h。
  8. 根据权利要求7所述的制备方法，其特征在于，所述碳源选自葡萄糖和蔗糖中的至少一种；
    优选地，所述核壳型磷酸锰铁与所述锂源的总质量与所述碳源的质量之比为100:4-6。
  9. 根据权利要求4-8中任一项所述的制备方法，其特征在于，所述铁源选自硫酸亚铁和硝酸亚铁中的至少一种；
    优选地，所述锰源选自硫酸锰和硝酸锰中的至少一种；
    优选地，所述锂源为氢氧化锂和碳酸锂中的至少一种；
    优选地，所述硼源为硼酸。
  10. 一种锂离子电池，其特征在于，包括权利要求1-2中任一项所述的磷酸锰铁锂正极材料或权利要求3-9中任一项所述的磷酸锰铁锂正极材料制备方法制备的磷酸锰铁锂正极材料。
PCT/CN2023/082550 2022-12-09 2023-03-20 一种磷酸锰铁锂正极材料、其制备方法及电池 WO2024119663A1 (zh)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202211583455.1A CN115724418B (zh) 2022-12-09 2022-12-09 一种磷酸锰铁锂正极材料、其制备方法及电池
CN202211583455.1 2022-12-09

Publications (1)

Publication Number Publication Date
WO2024119663A1 true WO2024119663A1 (zh) 2024-06-13

Family

ID=85301109

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2023/082550 WO2024119663A1 (zh) 2022-12-09 2023-03-20 一种磷酸锰铁锂正极材料、其制备方法及电池

Country Status (3)

Country Link
CN (1) CN115724418B (zh)
FR (1) FR3143207A1 (zh)
WO (1) WO2024119663A1 (zh)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115724418B (zh) * 2022-12-09 2024-05-10 广东邦普循环科技有限公司 一种磷酸锰铁锂正极材料、其制备方法及电池

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160181605A1 (en) * 2013-08-08 2016-06-23 Peking University Boron-doped lithium-rich manganese based materials and preparation methods for li-ion battery cathode
CN106299296A (zh) * 2016-05-10 2017-01-04 中国科学院过程工程研究所 一种核壳结构的磷酸锰铁锂材料及其制备方法和用途
CN106340639A (zh) * 2016-10-28 2017-01-18 合肥国轩高科动力能源有限公司 一种磷酸铁锂/碳包覆的核壳型磷酸锰铁锂复合正极材料及其制备方法
CN107623112A (zh) * 2017-08-18 2018-01-23 宁波知能新材料有限公司 掺锂磷酸硼修饰的碳包覆磷酸锰铁锂正极材料及其制备方法
CN115020678A (zh) * 2022-07-12 2022-09-06 远景动力技术(江苏)有限公司 正极活性材料、电化学装置和电子设备
CN115724418A (zh) * 2022-12-09 2023-03-03 广东邦普循环科技有限公司 一种磷酸锰铁锂正极材料、其制备方法及电池

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101740752B (zh) * 2009-12-16 2012-01-18 深圳市德方纳米科技有限公司 具有核壳结构的锂离子电池用复合正极材料及其制备方法
JP5999240B1 (ja) * 2015-09-30 2016-09-28 住友大阪セメント株式会社 リチウムイオン二次電池用電極材料およびその製造方法
US20210202940A1 (en) * 2018-04-19 2021-07-01 A123 Systems LLC. Method and systems for coated cathode materials and use of coated cathode materials
CN113224278B (zh) * 2021-05-07 2022-06-07 蜂巢能源科技有限公司 改性磷酸铁锰锂材料、其制备方法及应用
CN116143100A (zh) * 2023-02-28 2023-05-23 广东邦普循环科技有限公司 改性磷酸锰铁锂正极材料及其前驱体与制备方法、电池

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160181605A1 (en) * 2013-08-08 2016-06-23 Peking University Boron-doped lithium-rich manganese based materials and preparation methods for li-ion battery cathode
CN106299296A (zh) * 2016-05-10 2017-01-04 中国科学院过程工程研究所 一种核壳结构的磷酸锰铁锂材料及其制备方法和用途
CN106340639A (zh) * 2016-10-28 2017-01-18 合肥国轩高科动力能源有限公司 一种磷酸铁锂/碳包覆的核壳型磷酸锰铁锂复合正极材料及其制备方法
CN107623112A (zh) * 2017-08-18 2018-01-23 宁波知能新材料有限公司 掺锂磷酸硼修饰的碳包覆磷酸锰铁锂正极材料及其制备方法
CN115020678A (zh) * 2022-07-12 2022-09-06 远景动力技术(江苏)有限公司 正极活性材料、电化学装置和电子设备
CN115724418A (zh) * 2022-12-09 2023-03-03 广东邦普循环科技有限公司 一种磷酸锰铁锂正极材料、其制备方法及电池

Also Published As

Publication number Publication date
FR3143207A1 (fr) 2024-06-14
CN115724418A (zh) 2023-03-03
CN115724418B (zh) 2024-05-10

Similar Documents

Publication Publication Date Title
JP6380608B2 (ja) リチウム複合化合物粒子粉末の製造方法、リチウム複合化合物粒子粉末を非水電解質二次電池に用いる方法
Tang et al. Synthesis and electrochemical performance of lithium-rich cathode material Li [Li0. 2Ni0. 15Mn0. 55Co0. 1-xAlx] O2
TWI501456B (zh) Non-aqueous electrolyte battery negative electrode material and non-aqueous electrolyte battery anode material manufacturing method and lithium-ion battery
WO2007131411A1 (en) A positive electrode material for secondary battery and the preparation method of the same
CN112885995B (zh) 一种磷酸铁锰锂包覆高压镍锰酸锂正极材料的制造方法
CN111697203B (zh) 一种磷酸锰铁锂复合材料及其制备方法和应用
CN114665058A (zh) 一种锂离子电池正极材料磷酸锰铁锂的制备方法
CN110970618A (zh) 一种低成本磷酸铁锂复合材料的制备方法
WO2024119663A1 (zh) 一种磷酸锰铁锂正极材料、其制备方法及电池
CN113353985A (zh) 一种锂离子电池正极材料及其制备方法、锂离子电池的正极和锂离子电池
JP2023103440A (ja) リチウムイオン二次電池用正極活物質の製造方法
TWI550938B (zh) 鋰離子電池正極材料及其製備方法
CN113745504A (zh) 一种铌钨钛氧化物负极材料及其制备方法与应用
CN111211302B (zh) 锂离子电池正极材料及其制备方法、锂离子电池正极、锂离子电池和用电设备
CN117525391A (zh) 一种钠离子电池聚阴离子正极材料及其制备方法
CN116779836A (zh) 补锂材料及制备方法、正极极片、储能装置和用电装置
CN107834054B (zh) 一种锂离子电池用镍锰酸锂-石墨烯复合材料的制备方法
Yang et al. Fast preparation of LiFePO4 nanoparticles for lithium batteries by microwave-assisted hydrothermal method
CN114864894A (zh) 一种耐高压包覆层修饰的富锂锰基正极材料及其制备方法和应用
CN114614012A (zh) 一种用于全固态电池的三元复合材料、其制备方法及其应用
CN113764671A (zh) 一种锂离子电池正极材料
CN114220969A (zh) 一种硅酸钛锂的制备方法
KR20120096251A (ko) 리튬 이온 이차 전지용 양극 활물질의 제조 방법
CN115367723B (zh) 一种LiFe2F6包覆磷酸铁锂正极材料的制备方法
WO2024032550A1 (zh) 电池材料及其制备方法、和二次电池