WO2023138618A1 - 一种正极材料及包括该材料的正极片和电池 - Google Patents

一种正极材料及包括该材料的正极片和电池 Download PDF

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WO2023138618A1
WO2023138618A1 PCT/CN2023/072901 CN2023072901W WO2023138618A1 WO 2023138618 A1 WO2023138618 A1 WO 2023138618A1 CN 2023072901 W CN2023072901 W CN 2023072901W WO 2023138618 A1 WO2023138618 A1 WO 2023138618A1
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positive electrode
solution
present disclosure
electrode material
reaction
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PCT/CN2023/072901
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English (en)
French (fr)
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曾家江
李素丽
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珠海冠宇电池股份有限公司
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Priority claimed from CN202210072994.2A external-priority patent/CN114530595A/zh
Priority claimed from CN202210082272.5A external-priority patent/CN114447321A/zh
Application filed by 珠海冠宇电池股份有限公司 filed Critical 珠海冠宇电池股份有限公司
Publication of WO2023138618A1 publication Critical patent/WO2023138618A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the disclosure belongs to the technical field of batteries, and relates to a positive electrode material, a positive electrode sheet including the material, and a battery.
  • Batteries have been widely used in portable appliances and power storage systems, realizing the wireless revolution of mobile phones, notebook computers and digital cameras, and are key components of portable appliances and telecommunication equipment needed in today's society.
  • the cathode material is closely related to the performance of the battery.
  • olivine-type positive electrode materials have low electronic conductivity and lithium ion diffusion coefficient, and have significant shortcomings in rate performance and low-temperature performance, which affect battery performance, and the preparation process is complicated, which limits their large-scale production.
  • the present disclosure provides a positive electrode material and a preparation method thereof, a positive electrode sheet including the positive electrode material, and a battery including the positive electrode sheet.
  • the median particle size of the positive electrode material is selected within a certain range, and a battery with better kinetic performance, low-temperature discharge performance and high safety performance can be obtained.
  • a positive electrode material comprising a positive electrode active material and a coating material on the surface of the positive electrode active material;
  • the median particle diameter D50 of the positive electrode material is 2 ⁇ m to 7 ⁇ m, for example, the median particle diameter D50 of the positive electrode material is 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m or any value in the range consisting of the above two endpoints;
  • the M is selected from at least one of niobium (Nb), magnesium (Mg), cobalt (Co), zinc (Zn), nickel (Ni) or copper (Cu), such as niobium (Nb).
  • the N is selected from at least one of aluminum (Al), titanium (Ti), vanadium (V) or cerium (Ce), such as vanadium (V).
  • the cathode active material has an olivine-type structure.
  • the positive electrode active material is a secondary spherical particle
  • the secondary spherical particle includes a core region and a shell region, the shell region is located on the outer layer of the core region; the shell region has an agglomerated dense structure; the inner core region has an agglomerated loose structure.
  • the hollow structure can provide multiple paths for the diffusion of lithium ions, which solves the problems of low lithium diffusion rate and polarization of positive electrode materials in the prior art, and also makes the positive electrode sheet including the positive electrode material and the battery including the positive electrode sheet have good rate performance and kinetic performance, especially good low-temperature discharge performance.
  • the coating material includes a carbon material.
  • the carbon material comprises amorphous carbon.
  • the thickness of the cladding material is 2nm-10nm, for example, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm or any point value in the range composed of the above two endpoints.
  • FIG. 22 it is a TEM spectrum of the cathode active material described in an example of the present disclosure, and the thickness of “Carbon” marked in the lower right corner of the figure is the thickness of the coating material.
  • the positive electrode material has a specific surface area of 8m 2 /g to 25m 2 /g, such as 8m 2 /g, 9m 2 /g, 10m 2 /g, 11m 2 /g, 12m 2 /g, 13m 2 /g, 14m 2 /g, 15m 2 /g, 16m 2 /g, 17m 2 /g, 18m 2 /g, 19m 2 / g, 20m 2 /g, 21m 2 / g, 22m 2 /g, 23m 2 /g, 24m 2 / g, 25m 2 /g or any value in the range formed by the above two endpoints.
  • the chemical formula of the positive electrode active material is Li a Mn 1-yz M y N z PO 4 .
  • the chemical formula of the cathode active material is LiMnPO 4 .
  • the positive electrode active material is lithium manganese phosphate.
  • the median diameter D50 of the positive electrode material is 2 ⁇ m ⁇ 5 ⁇ m.
  • the shell region has pores.
  • the porosity of the shell region is 10% to 35%, such as 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, or any point value in the range formed by the above two extremes.
  • the porosity of the inner core region is greater than the porosity of the outer shell region.
  • the porosity of the inner core region is 60% to 90%, such as 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78%, 80%, 82%, 85%, 88%, 90%, or any point value in the range formed by the above two extremes.
  • the present disclosure does not specifically limit the test method of porosity, which can be measured by methods known in the art.
  • the coating material has a thickness of 2nm ⁇ 8nm.
  • the positive electrode material has a specific surface area of 15m 2 /g to 25m 2 /g, such as 15m 2 /g, 16m 2 /g, 17m 2 /g, 18m 2 /g, 19m 2 /g, 20m 2 / g, 21m 2 /g, 22m 2 /g, 23m 2 /g, 24m 2 /g, 25m 2 /g or the above Any point value in the range consisting of two endpoints. .
  • the electronic conductivity of the cathode material is 1.0 ⁇ 10 ⁇ 5 S/cm ⁇ 9.0 ⁇ 10 ⁇ 5 S/cm.
  • the lithium ion diffusion coefficient of the cathode material is 1.0 ⁇ 10 ⁇ 14 cm 2 /s ⁇ 8.0 ⁇ 10 ⁇ 14 cm 2 /s.
  • the mass of the positive electrode active material accounts for 97.5wt% to 99.0wt% of the total mass of the positive electrode material, such as 97.5wt%, 98wt%, 98.5wt%, 99wt%, or any point value in the range composed of the above two endpoints.
  • the mass of the coating material accounts for 1wt% to 2.5wt% of the total mass of the positive electrode material, such as 1wt%, 1.5wt%, 2wt%, 2.5wt%, or any value in the range formed by the above two endpoints.
  • the median diameter D50 of the core region of the positive electrode active material is 1.2 ⁇ m to 2.6 ⁇ m, such as 1.2 ⁇ m, 1.3 ⁇ m, 1.4 ⁇ m, 1.5 ⁇ m, 1.6 ⁇ m, 1.7 ⁇ m, 1.8 ⁇ m, 1.9 ⁇ m, 2 ⁇ m, 2.1 ⁇ m, 2.2 ⁇ m, 2.3 ⁇ m, 2.4 ⁇ m, 2.5 ⁇ m, 2.6 ⁇ m ⁇ m or any point value in the range formed by the above two endpoints.
  • the inner core region and the outer shell region have the same composition, both being lithium manganese phosphate LiMnPO 4 .
  • the secondary spherical particles refer to a spherical secondary particle structure formed by stacking lithium manganese phosphate primary particles.
  • the inner core region is formed by agglomeration of lithium manganese phosphate primary particles with a small particle size (200nm-300nm), and the inner core region is an agglomerated loose structure with a porosity of 60%-90%.
  • the shell region is formed by agglomeration of lithium manganese phosphate primary particles with a large particle size (300nm-500nm), and the shell region is an agglomerated dense structure with a porosity of 10%-35%.
  • the chemical formula of the positive electrode active material is Li a FexMyNzPO4 .
  • the chemical formula of the cathode active material is LiFePO 4 .
  • the positive electrode active material is lithium iron phosphate.
  • the shell region has pores.
  • the porosity of the shell region is 10% to 35%, such as 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, or any point value in the range formed by the above two extremes.
  • the porosity of the inner core region is greater than the porosity of the outer shell region.
  • the porosity of the inner core region is 60% to 90%, such as 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78%, 80%, 82%, 85%, 88%, 90%, or any point value in the range formed by the above two extremes.
  • the present disclosure does not specifically limit the test method of porosity, which can be measured by methods known in the art.
  • the coating material has a thickness of 2nm ⁇ 8nm.
  • the specific surface area of the positive electrode material is 8m 2 /g to 15m 2 /g, such as 8m 2 /g, 9m 2 /g, 10m 2 /g, 11m 2 /g, 12m 2 /g, 13m 2 /g, 14m 2 /g, 15m 2 / g or any point value in the range formed by the above two endpoints.
  • the electronic conductivity of the cathode material is 2.0 ⁇ 10 -2 S/cm ⁇ 9.0 ⁇ 10 -2 S/cm.
  • the lithium ion diffusion coefficient of the positive electrode material is 1.0 ⁇ 10 ⁇ 11 cm 2 /s ⁇ 9.0 ⁇ 10 ⁇ 11 cm 2 /s.
  • the mass of the positive electrode active material accounts for 97.5wt% to 99.0wt% of the total mass of the positive electrode material, such as 97.5wt%, 98wt%, 98.5wt%, 99wt%, or any point value in the range composed of the above two endpoints.
  • the mass of the coating material accounts for 1wt% to 2.5wt% of the total mass of the positive electrode material, such as 1wt%, 1.5wt%, 2wt%, 2.5wt%, or any value in the range formed by the above two endpoints.
  • the median diameter D50 of the core region of the positive electrode active material is 1.2 ⁇ m to 2.6 ⁇ m, such as 1.2 ⁇ m, 1.3 ⁇ m, 1.4 ⁇ m, 1.5 ⁇ m, 1.6 ⁇ m, 1.7 ⁇ m, 1.8 ⁇ m, 1.9 ⁇ m, 2 ⁇ m, 2.1 ⁇ m, 2.2 ⁇ m, 2.3 ⁇ m, 2.4 ⁇ m, 2.5 ⁇ m, 2.6 ⁇ m ⁇ m or any point value in the range formed by the above two endpoints.
  • the inner core region and the outer shell region have the same composition, which is lithium iron phosphate LiFePO 4 .
  • the secondary spherical particles refer to a spherical secondary particle structure formed by stacking lithium iron phosphate primary particles.
  • the core region is formed by agglomeration of lithium iron phosphate primary particles with a small particle size (200nm-300nm), and the core region is an agglomerated loose structure with a porosity of 60%-90%.
  • the shell region is formed by agglomeration of lithium iron phosphate primary particles with a large particle size (300nm-500nm), and the shell region is an agglomerated dense structure with a porosity of 10%-35%.
  • the chemical formula of the positive electrode active material is LiFexMn1 - xyzMyNzPO4 .
  • 0 ⁇ y+z ⁇ 0.04 specifically, 0.0015 ⁇ y+z ⁇ 0.04, for example, y+z is 0.0015, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03 or 0.04.
  • the molar ratio of M and N is (1-3):1, such as 1:1, 2:1, 3:1 or any value in the range formed by the above two endpoints.
  • the shell region has pores.
  • the porosity of the shell region is greater than 0 and less than or equal to 30%, such as 0.1%, 0.5%, 1%, 5%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, or any point value in the range formed by the above two endpoints.
  • the porosity of the inner core region is greater than the porosity of the outer shell region.
  • the porosity of the inner core region is 65% to 90%, such as 65%, 68%, 70%, 72%, 75%, 78%, 80%, 82%, 85%, 88%, 90%, or any point value in the range formed by the above two extremes. .
  • the present disclosure does not specifically limit the test method of porosity, which can be measured by methods known in the art.
  • the median diameter D50 of the core region of the secondary spherical particles is 1.0 ⁇ m to 2.8 ⁇ m, such as 1.0 ⁇ m, 1.1 ⁇ m, 1.2 ⁇ m, 1.3 ⁇ m, 1.4 ⁇ m, 1.5 ⁇ m, 1.6 ⁇ m, 1.7 ⁇ m, 1.8 ⁇ m, 1.9 ⁇ m, 2 ⁇ m, 2.1 ⁇ m, 2.2 ⁇ m, 2.3 ⁇ m, 2.4 ⁇ m, 2.5 ⁇ m, 2.6 ⁇ m, 2.7 ⁇ m, 2.8 ⁇ m or any point value in the range formed by the above two endpoints.
  • the specific surface area of the positive electrode material is 10m 2 /g ⁇ 18m 2 /g, such as 10m 2 /g, 11m 2 /g, 12m 2 /g, 13m 2 /g, 14m 2 /g, 15m 2 /g, 16m 2 /g, 17m 2 /g, 18m 2 / g or any point value in the range formed by the above two endpoints.
  • the discharge gram capacity of the positive electrode material is greater than 150mAh/g, preferably greater than 150mAh/g and less than 200mAh/g.
  • the present disclosure also provides a positive electrode sheet, which includes the above positive electrode material.
  • the positive electrode sheet can be prepared according to a method known in the art, for example, may also include a conductive agent, a binder or other materials known in the art, which are not specifically limited in the present disclosure.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active layer located on the surface of the positive electrode current collector; the positive electrode active layer includes the above-mentioned positive electrode material.
  • the mass percentage of each component in the positive electrode active layer is: 70wt%-99wt% of the positive electrode material, 0.5wt%-15wt% of the conductive agent and 0.5wt%-15wt% of the binder.
  • the mass percentage of each component in the positive active layer is:
  • PVDF binder polyvinylidene fluoride
  • the mass percentage of each component in the positive electrode active layer is:
  • PVDF binder polyvinylidene fluoride
  • the present disclosure also provides an application of the above-mentioned positive electrode material or the above-mentioned positive electrode sheet in a battery.
  • the present disclosure also provides a battery, which includes the above-mentioned positive electrode material or the above-mentioned positive electrode sheet.
  • the battery is a lithium ion battery.
  • the battery can be prepared according to methods known in the art, for example, it can also include a negative electrode, a separator, and an electrolyte, etc.
  • the negative electrode, the separator, and the electrolyte can be selected according to methods known in the art, and are not specifically limited in the present disclosure.
  • the volumetric energy density of the battery is 225KWh/m 3 -255KWh/m 3
  • the gravimetric energy density is 175Wh/kg-215Wh/kg.
  • the rate capability of the battery is greater than 90%, preferably 91%-99%.
  • the cycle capacity retention rate of the battery after charging and discharging cycles at a temperature of 25°C ⁇ 2°C is 90% or above, preferably 90%-99%.
  • the EIS impedance value of the battery is less than or equal to 6m ⁇ , preferably 0.1m ⁇ ⁇ 6m ⁇ .
  • the rate capability described in the present disclosure refers to the ratio of the 10C discharge capacity to the 0.33C discharge capacity of the battery at 25°C.
  • the positive electrode material of the present disclosure is a microsphere with a core-shell structure, and the shell has an agglomerated and dense structure; the core has an agglomerated loose structure (even the central part is hollow), and the special core-shell structure can alleviate the stress load caused by particle expansion and contraction during charging and discharging of the battery, thereby achieving the purpose of improving the rate performance and cycle performance;
  • the positive electrode active material of the present disclosure is a microsphere with a core-shell structure, and the particle size is controllable.
  • the shell in the positive electrode active material has a dense structure of reunion;
  • the core in the positive electrode active material has a loose structure of reunion (even its center part is hollow), and this structure is conducive to improving the wetting effect of the electrolyte.
  • the internal loose structure shortens the diffusion distance of lithium ions and shortens the diffusion path of lithium ions. Diffusion ability and polarization effect are significantly improved;
  • the positive electrode material of the present disclosure forms an effective synergistic effect between the two elements through the doping of two elements, so that the electronic conductivity and lithium ion diffusion rate of lithium manganese iron phosphate are significantly improved, and it has good electrochemical performance when applied to batteries.
  • Metal ion doping improves the electronic conductivity and ion diffusion rate of lithium iron phosphate
  • the synergistic effect of dual element doping can improve the discharge capacity and cycle performance of lithium iron phosphate cathode materials. Compared with single element doping or no doping, it can improve the electrochemical performance of lithium iron phosphate in many ways;
  • the present disclosure adopts the positive electrode material to prepare the positive electrode sheet and has excellent cycle performance and high output power performance when applied to the lithium battery level, and has high safety performance when applied to the battery level;
  • the positive electrode material of the present disclosure is made into a positive electrode sheet and applied to a battery, the first charge and discharge efficiency, coulombic efficiency, low temperature performance, rate performance and safety performance of the battery cell are significantly improved, and the problems of low lithium ion diffusion rate and polarization phenomenon of lithium manganese phosphate in the prior art are solved, and the safety performance and rate performance of the material are significantly improved.
  • FIG. 1 is a schematic structural view of the positive electrode material of the present disclosure
  • Fig. 2 is the XRD figure of the cathode material of embodiment 1;
  • Fig. 3 is the SEM sectional view of the positive electrode material of embodiment 1;
  • Fig. 4 is the SEM sectional view of the positive electrode material of comparative example 1;
  • Fig. 5 is the XRD figure of the lithium manganese iron phosphate cathode material of embodiment 5;
  • Fig. 6 is the SEM figure of the lithium manganese iron phosphate cathode material of embodiment 5;
  • Fig. 7 is the cross-sectional SEM figure of the lithium manganese iron phosphate positive electrode material of embodiment 5;
  • Fig. 8 is the nitrogen adsorption-desorption curve of the lithium manganese iron phosphate positive electrode material of embodiment 5;
  • Fig. 9 is the cross-sectional SEM figure of the positive electrode material of embodiment 9;
  • Fig. 10 is the XRD spectrum of the doped lithium manganese iron phosphate positive electrode material of embodiment 9;
  • Fig. 12 is the charge-discharge curve (button cell) of embodiment 1;
  • Fig. 13 is the charge-discharge curve (button cell) of comparative example 1;
  • Fig. 14 is the charge-discharge curve (button cell) of embodiment 5;
  • Fig. 15 is the charge-discharge curve (button cell) of comparative example 2;
  • Fig. 16 is the charging and discharging curve of embodiment 9;
  • Fig. 17 is the rate performance figure of embodiment 5 (soft pack electric core);
  • Figure 18 is a graph of the 45°C cycle capacity retention of Example 9;
  • Figure 19 is the cycle capacity retention rate of the pouch cell of Example 1 at 25°C;
  • Figure 20 is the cycle capacity retention rate of the pouch cell in Example 1 at 45°C;
  • Fig. 21 is the impedance figure of embodiment 9;
  • FIG. 22 is a TEM spectrum of a cathode active material in an example of the present disclosure.
  • the present disclosure also provides a method for preparing the above-mentioned positive electrode material.
  • the preparation method includes the following steps:
  • A1 respectively configuring the precursor solution of the positive electrode active material, the complexing agent solution, the pH adjustment solution and the reaction solution;
  • step A2) Inject the precursor solution of the positive electrode active material, the complexing agent solution and the pH adjustment solution into the reaction solution in step A1) to carry out the first co-precipitation reaction to obtain a solution containing the crystal nucleus of the positive electrode active material precursor;
  • step A3) re-inject the complexing agent solution and the pH adjustment solution in step A1) into the solution containing the crystal nucleus of the positive electrode active material precursor obtained in the above step A2), and carry out the second co-precipitation reaction until the target particle size is obtained after the reaction is terminated, and the Mn 3 (PO 4 ) 2 positive electrode active material precursor is prepared;
  • step A4 uniformly dispersing the Mn 3 (PO 4 ) 2 cathode active material precursor obtained in step A3) into the Li 3 PO 4 crystal solution for crystal nucleus growth to obtain the LiMnPO 4 precursor;
  • step A5) Mix the LiMnPO 4 precursor obtained in step A4) with a carbon source, and perform high-temperature calcination under an inert atmosphere to prepare the positive electrode material.
  • the precursor solution of the cathode active material includes manganese ions (Mn 2+ ) and phosphate ions (PO 4 3 ⁇ ).
  • the manganese ions are provided by a manganese salt.
  • the manganese salt is selected from at least one of (CH 3 COO) 2 Mn, MnSO 4 , MnC 2 O 4 or MnCl 2 .
  • the phosphate ions are provided by a phosphate ion-containing water-soluble compound.
  • the water-soluble compound containing phosphate ions is selected from phosphoric acid or other soluble phosphates, and the soluble phosphates are selected from at least one of (NH 4 )H 2 PO 4 , (NH 4 ) 2 HPO 4 or (NH 4 ) 3 PO 4 .
  • the total molar concentration of the manganese ions (Mn 2+ ) and the phosphate ions (PO 4 3 ⁇ ) is 1 mol/L ⁇ 3 mol/L.
  • the molar ratio of the phosphate ion (PO 4 3 ⁇ ) to the manganese ion (Mn 2+ ) is (0.98 ⁇ 1.05):1.
  • the complexing agent solution contains a complexing agent.
  • the complexing agent is selected from at least one of oxalic acid, citric acid or EDTA.
  • the concentration of the complexing agent solution is 1 mol/L ⁇ 3 mol/L.
  • the pH adjusting solution contains organic acid and/or inorganic acid.
  • the organic acid is selected from acetic acid or oxalic acid.
  • the inorganic acid is selected from carbonic acid.
  • the concentration of the pH adjusting solution is 0.025mol/L ⁇ 0.30mol/L.
  • the reaction liquid is a mixed solvent composed of alcohol solvent and water.
  • the alcohol solvent is at least one selected from ethylene glycol, glycerol, polyethylene glycol 400 or polyethylene glycol 200.
  • the volume ratio of the alcohol solvent to the water is (1-5):1, preferably (2-3):1.
  • step A2) is a stage of nucleation and core growth of the positive electrode active material precursor.
  • step A2) and step A3) the reaction conditions of step A2) and step A3) are controlled by adjusting the addition amount of the complexing agent solution and the pH adjustment solution.
  • the reaction conditions include: the pH value is 1.5-2.4, and the complexing agent concentration is 0.02mol/L-0.05mol/L. Under these conditions, an inner core region with an agglomerated loose structure can be prepared.
  • step A2) the time of the first co-precipitation reaction is 8h-20h, the temperature of the first co-precipitation reaction is 50°C-75°C, and an inert gas, such as nitrogen, is continuously introduced during the first co-precipitation reaction.
  • step A3) is the shell production stage of the positive electrode active material precursor.
  • the molecular formula of the positive electrode active material in the positive electrode material precursor is Mn 3 (PO 4 ) 2 .
  • the reaction conditions include: the pH value is 2.6-3.5, and the complexing agent concentration is 0.1mol/L-0.3mol/L. Under these conditions, a shell region with an agglomerated and dense structure can be prepared.
  • step A3) the time of the second co-precipitation reaction is 48h-96h, the temperature of the second co-precipitation reaction is 50°C-75°C, and an inert gas, such as nitrogen, is continuously introduced during the second co-precipitation reaction.
  • both the first co-precipitation reaction and the second co-precipitation reaction are performed under stirring conditions, preferably, the stirring rate of the first co-precipitation reaction is greater than the stirring rate of the second co-precipitation reaction.
  • the stirring rate of the first co-precipitation reaction is 200rpm-650rpm
  • the stirring rate of the second co-precipitation reaction is 150rpm-500rpm.
  • the target particle size means that D50 is controlled at 2 ⁇ m ⁇ 5 ⁇ m.
  • step A3) also includes performing solid-liquid separation, aging, drying, grinding, screening and impurity removal on the reacted slurry to obtain the Mn 3 (PO 4 ) 2 cathode active material precursor.
  • the Li 3 PO 4 crystal solution is prepared by the following method:
  • the phosphoric acid solution is added to the LiOH solution for reaction to form the Li 3 PO 4 crystal solution.
  • the phosphoric acid solution is an aqueous phosphoric acid solution with a molar concentration of 1.0mol/L to 2.5mol/L;
  • the LiOH solution is an aqueous LiOH solution with a molar concentration of 1.0mol/L to 2.5mol/L;
  • the molar ratio of Li + to PO 4 3- in the system is (0.96 to 1.10):1.
  • the amount of Li 3 PO 4 and Mn 3 (PO 4 ) 2 added is based on the molar ratio of Li + to Mn 2+ in the system as (0.96 ⁇ 1.10):1.
  • the carbon source is selected from organic carbon sources and/or inorganic carbon sources.
  • the organic carbon source is selected from at least one of glucose, sucrose, lemon sugar, polyaniline or PEDOT conductive polymer.
  • the inorganic carbon source is selected from at least one of carbon nanotubes, conductive graphene or conductive carbon black.
  • the mixing is, for example, at least one of stirring, ball milling or grinding.
  • the inert atmosphere includes at least one of nitrogen or argon.
  • the mass ratio (g/g) of the carbon source to the LiMnPO 4 precursor is (0.07 ⁇ 0.12):1.
  • the calcination includes multi-stage temperature-controlled sintering, which specifically includes the following steps: raising the temperature from room temperature to 500°C-600°C at a rate of 3°C/min, first keeping the temperature at 500°C-600°C for 4h-6h, and then raising the temperature to 650°C-800°C for 8h-12h to obtain the positive electrode material.
  • step A5) the carbon source is decomposed into amorphous carbon at high temperature and uniformly deposited on the surface of the positive electrode active material.
  • the present disclosure provides a preparation method of a battery, the battery includes a positive electrode sheet, a negative electrode sheet, a commercial battery separator and an electrolyte, and a commercial battery is prepared by a standardized operation method, which can be applied at the level of a soft pack cell or a cylindrical cell, and has high commercial value and practical significance.
  • the present disclosure also provides another preparation method for the above-mentioned positive electrode material.
  • the positive electrode active material as Li a Fex Mn 1-xyz My N z PO 4 , 0 ⁇ x ⁇ 0.6, 0 ⁇ y ⁇ 0.02, 0 ⁇ z ⁇ 0.02 (wherein M and N are co-doped elements) as an example
  • the preparation method specifically includes the following steps:
  • the nucleation and core growth stage of the positive electrode material precursor inject the precursor ternary solution, complexing agent solution and pH adjustment solution of the positive electrode active material in step B1) into the reaction solution to undergo the first co-precipitation, and obtain a solution containing the crystal nucleus of the positive electrode active material precursor;
  • the shell production stage of the positive electrode material precursor re-inject the complexing agent solution and the pH adjustment solution into the solution containing the positive electrode active material precursor crystal nucleus obtained in the above step B2), and carry out the second co-precipitation under stirring until the target particle size D50 is obtained after the reaction is terminated to obtain the positive electrode material precursor;
  • step B4 ball milling and mixing the positive electrode material precursor, phosphate, lithium salt, and carbon source obtained in step B3), and performing high-temperature calcination under an inert atmosphere to obtain the positive electrode material.
  • the precursor ternary solution of the cathode active material includes ferrous ions (Fe 2+ ), manganese ions (Mn 2+ ) and phosphate ions (PO 4 3 ⁇ ).
  • the ferrous ions are provided by a soluble ferrous salt.
  • the soluble ferrous salt is at least one selected from FeC 2 O 4 , FeSO 4 , FeCl 2 or (CH 3 COO) 2 Fe.
  • the manganese ions are provided by a manganese salt.
  • the manganese salt is selected from at least one of (CH 3 COO) 2 Mn, MnSO 4 , MnC 2 O 4 or MnCl 2 .
  • the phosphate ions are provided by a phosphate ion-containing water-soluble compound.
  • the water-soluble compound containing phosphate ions is selected from phosphoric acid or other soluble phosphates, and the soluble phosphates are selected from at least one of (NH 4 )H 2 PO 4 , (NH 4 ) 2 HPO 4 or (NH 4 ) 3 PO 4 .
  • the molar ratio of the sum of the ferrous ion and the manganese ion (Fe 2+ +Mn 2+ ) to the phosphate ion (PO 4 3 ⁇ ) is (2.85 ⁇ 3.15):2.
  • the total molar concentration of the ferrous ions (Fe 2+ ), the manganese ions (Mn 2+ ) and the phosphate ions (PO 4 3 ⁇ ) is 1 mol/L ⁇ 3 mol/L.
  • the complexing agent solution contains a complexing agent.
  • the complexing agent is selected from at least one of oxalic acid, citric acid or EDTA.
  • the concentration of the complexing agent is 1 mol/L ⁇ 3 mol/L.
  • the pH adjustment solution contains organic acid and/or inorganic acid.
  • the organic acid is selected from acetic acid or oxalic acid.
  • the inorganic acid is selected from carbonic acid.
  • the concentration of the pH adjustment solution is 0.05mol/L ⁇ 0.25mol/L.
  • the blending solution contains vanadium ions and niobium ions.
  • the vanadium ions are provided by a vanadium salt, eg the vanadium salt is selected from sulfate or chloride salts of vanadium.
  • said niobium ions are provided by a niobium salt, eg said niobium salt is selected from sulfate or chloride salts of niobium.
  • the molar ratio of the vanadium ions to the niobium ions is (0.5 ⁇ 2):1.
  • the concentration of the blended solution is 0.01mol/L ⁇ 0.05mol/L.
  • the reaction liquid is a mixed solvent composed of alcohol solvent and water.
  • the alcohol solvent is selected from at least one of ethylene glycol, glycerol, polyethylene glycol 400 or polyethylene glycol 200 A sort of.
  • the volume ratio of the alcohol solvent to water is (1-5):1, preferably (2-3):1.
  • the particle diameter D50 of the crystal nucleus is 1.0 ⁇ m ⁇ 2.8 ⁇ m.
  • step B2) the (Fe 2+ +Mn 2+ ):(V 5+ +Nb 5+ ) molar ratio is (99.1 ⁇ 99.9):(0.1 ⁇ 0.9), for example, 99.5:0.5 or 99.6:0.4.
  • the reaction temperature is 50° C. to 70° C.
  • an inert gas such as nitrogen
  • the reaction conditions of step B2) and step B3) are controlled by adjusting the addition amount of the complexing agent solution and the pH adjustment solution.
  • the reaction conditions include: a pH value of 1.5-2.4, and a concentration of the complexing agent of 0.02mol/L-0.05mol/L.
  • the first co-precipitation reaction time is 8h-20h.
  • the reaction conditions include: a pH value of 2.6-3.5, and a concentration of the complexing agent of 0.1 mol/L-0.25 mol/L.
  • step B3) the second co-precipitation reaction time is 48h-96h.
  • both the first co-precipitation and the second co-precipitation are carried out under stirring conditions, preferably, the stirring rate during the first co-precipitation is greater than the stirring rate during the second co-precipitation.
  • the stirring speed of the first co-precipitation is 200rpm-650rpm
  • the stirring speed of the second co-precipitation is 150rpm-500rpm.
  • the target particle size means that the particle size D50 is controlled within 3 ⁇ m ⁇ 7 ⁇ m.
  • the positive active precursor is obtained by performing solid-liquid separation, aging, drying, grinding, screening and impurity removal on the reacted slurry.
  • the core region of the positive electrode active precursor is composed of agglomerated and loose micro-particles formed by the crystal nucleus described in step B2), and the outer shell region of the surface layer is composed of agglomerated dense large particles, and the particle composition of the core region and the shell region is consistent.
  • step B4) the molar ratio of lithium ions (Li + ) in the lithium salt to the sum of the ferrous ions, the manganese ions, and optionally the vanadium ions and the niobium ions is (0.96-1.10):1.
  • the lithium salt is at least one selected from lithium carbonate, lithium hydroxide, lithium oxalate or lithium acetate.
  • the molar ratio of the phosphate ion (PO 4 3- ) in the phosphorus salt to the sum of the ferrous ion, the manganese ion, and optionally the vanadium ion and the niobium ion is (0.95-1.10):1.
  • the phosphorus salt is selected from at least one of the above-mentioned water-soluble compounds containing phosphate ions.
  • the carbon source is selected from organic carbon sources and/or inorganic carbon sources.
  • the organic carbon is selected from at least one of glucose, sucrose, lemon sugar, polyaniline or PEDOT conductive polymer.
  • step B4) the mass ratio (g/g) of the carbon source to the cathode material precursor is (0.07 ⁇ 0.10):1.
  • the calcination includes multi-stage temperature-controlled sintering, which specifically includes the following steps: raising the temperature from room temperature to 500°C-600°C at a heating rate of 3°C/min, first keeping the temperature at 500°C-600°C for 4h-6h, and then raising the temperature to 650°C-800°C and keeping it for 8h-12h to obtain the positive electrode material.
  • the carbon source is decomposed into amorphous carbon at high temperature and uniformly deposited on the surface of the positive electrode active material .
  • This disclosure optimizes the conventional co-precipitation method to prepare a core-shell structure precursor with different inner and outer primary particle structures, and provides a new idea for preparing anode materials with a special core-shell structure.
  • the disclosure can overcome the deficiencies and defects of lithium manganese iron phosphate positive electrode material prepared by conventional synthesis methods, such as high impedance and poor cycle performance, and has better electrochemical performance when applied to the battery level;
  • the binary solution includes MnSO 4 and H 3 PO 4 , the molar concentration of the binary solution is 1.5mol/L, and the molar ratio of PO 4 3- and Mn 2+ in the system is 1.02:1;
  • the reaction solution is prepared and stirred, and the reaction solution is The mixed solvent of glycerin and water volume ratio is 2:1;
  • the concentration of oxalic acid solution is 1.25mol/L;
  • the concentration of acetic acid solution is 0.15mol/L;
  • Stage 1 inject the above mixed solution into the reactor, control the stirring speed at 400rpm, control the concentration of oxalic acid solution at 0.03mol/L, and control the pH value of the solution at 2.2 to form an intermediate reaction solution.
  • the co-precipitation reaction time of stage 1 is 12h. This process is the nucleation and core growth stage of the precursor, and the precursor crystal nucleus is obtained;
  • Stage 2 inject oxalic acid solution and acetic acid solution into the precursor crystal nucleus solution obtained in the above steps, adjust the pH value of the system to 3.0, control the concentration of complexing agent at 0.2mol/L, and carry out co-precipitation reaction at a stirring rate of 350rpm.
  • This stage is the shell production stage of the precursor. The reaction is terminated after the target particle size reaches 3.5 ⁇ m, and the Mn 3 (PO 4 ) 2 precursor is obtained; the core area of the precursor is composed of agglomerated and loose particles, and the shell area is composed of Agglomerated and dense large particles, the particles in the inner core area and the outer shell area are composed of Mn 3 (PO 4 ) 2 ;
  • Phosphoric acid solution is added to LiOH solution for reaction to form the Li 3 PO 4 crystal solution;
  • the phosphoric acid solution is an aqueous phosphoric acid solution, and its molar concentration is 1.25mol/L;
  • the LiOH solution is an aqueous LiOH solution, and its molar concentration is 1.5mol/L, and Li in the system + with PO 4 3-
  • the molar ratio is 1.02:1;
  • the Mn 3 (PO 4 ) 2 The precursor is uniformly dispersed to Li 3 PO 4
  • the crystal nucleation is grown in the crystal solution, the crystal nucleation reaction time is 8h, and the reaction is completed to obtain LiMnPO 4 Precursor, according to Li + with Mn 2+ Weigh Li with a molar ratio of 1.04:1 3 PO 4 with Mn 3 (PO 4 ) 2 ;
  • Glucose and LiMnPO 4 precursors were mixed according to the mass ratio of 0.10:1, and high-temperature roasting was carried out under an inert atmosphere.
  • multi-stage temperature-controlled sintering was adopted, and the heating rate was increased from room temperature to 580 ° C at a rate of 3 °C/min.
  • the temperature was kept at 580 °C for 4 hours, and then the temperature was raised to 700 °C for 8 hours.
  • the carbon content measured by the carbon-sulfur meter is 2.2% (mass ratio), and the specific surface area (BET value) is shown in Table 1.
  • the particle size D50 of the positive electrode material is 3.8 ⁇ m, and the porosity of the core area and the outer shell area are 75% and 26%, respectively, according to the test of the porosity tester.
  • Figure 2 is the XRD pattern of the lithium manganese phosphate cathode material in Example 1. It can be seen that the standard lithium manganese phosphate material prepared in Example 1 has a good matching result with the PDF card.
  • Example 3 is a SEM cross-sectional view of the positive electrode material of Example 1. It can be seen that the core area of the positive electrode material of Example 1 is composed of agglomerated and loose tiny particles, the shell area is composed of agglomerated dense large particles, and the core area is a loose structure, and part of it is a hollow structure.
  • NMP N-methylpyrrolidone
  • the positive electrode material prepared above the binder polyvinylidene fluoride (PVDF), the conductive agent acetylene black, and the carbon nanotubes according to the weight ratio of 96.5:1.5:1.5:0.5, add N-methylpyrrolidone (NMP), and stir under the action of a vacuum mixer until the mixed system forms a positive electrode slurry with uniform fluidity.
  • NMP N-methylpyrrolidone
  • mPa.s evenly coat the positive electrode slurry on a carbon-coated aluminum foil with a thickness of (10+2) ⁇ m, and control the surface density at 15mg/cm 2 ⁇ 18mg/cm 2 ;
  • the above-mentioned coated aluminum foil is baked in 5 ovens with different temperature gradients, and then rolled and cut to obtain the required positive electrode sheet.
  • a 7 ⁇ m + 3 ⁇ m mixed-coated separator (substrate polypropylene film + PVDF & ceramic mixed coating) was selected (provided by Asahi Kasei).
  • the above-mentioned positive electrode sheet, separator and negative electrode sheet are stacked in order, and the negative electrode sheet is wrapped with two layers of separators to ensure that the separator is between the positive and negative electrode sheets for isolation, and then the bare cell without liquid injection is obtained by winding; the bare cell is placed in the outer packaging foil, the electrolyte prepared above is injected into the dried bare cell, and the soft-packed cell is obtained through the processes of vacuum packaging, standing, forming, shaping, and sorting.
  • the binary solution includes MnCl 2 and H 3 PO 4 , the molar concentration of the binary solution is 1.25mol/L, and the molar ratio of PO 4 3- to Mn 2+ in the system is 0.98:1;
  • the reaction solution is prepared and stirred, and the reaction solution is a mixed solvent with a volume ratio of ethylene glycol and water of 2:1;
  • the concentration of EDTA solution is 1.25mol/L;
  • oxalic acid The solution concentration is 0.15mol/L;
  • Stage 1 inject the above mixed solution into the reactor, control the stirring speed at 420rpm, control the concentration of EDTA solution at 0.05mol/L, and control the pH value of the solution at 2.0 to form an intermediate reaction solution.
  • the co-precipitation reaction time of stage 1 is 10h. This process is the nucleation and core growth stage of the precursor, and the precursor crystal nucleus is obtained;
  • Stage 2 Inject EDTA solution and oxalic acid solution into the precursor crystal nucleus solution obtained in the above steps, adjust the pH value of the system to 3.0, control the concentration of complexing agent at 0.25mol/L, and carry out co-precipitation reaction at a stirring rate of 360rpm.
  • This stage is the shell production stage of the precursor. The reaction is terminated after the target particle size reaches 3.0 ⁇ m, and the Mn 3 (PO 4 ) 2 precursor is obtained; the core area of the precursor is composed of agglomerated and loose particles, and the shell area Composed of agglomerated and dense large particles, the particles in the inner core area and the outer shell area are composed of Mn 3 (PO 4 ) 2 ;
  • Phosphoric acid solution is added to LiOH solution for reaction to form the Li 3 PO 4 crystal solution;
  • the phosphoric acid solution is an aqueous phosphoric acid solution, and its molar concentration is 1.0mol/L;
  • the LiOH solution is an aqueous LiOH solution, and its molar concentration is 1.25mol/L, and Li in the system + with PO 4 3- Molar ratio is 1.05:1;
  • the Mn 3 (PO 4 ) 2 The precursor is uniformly dispersed to the Li 3 PO 4
  • the crystal nucleus grows in the crystal solution, the crystal nucleus reaction time is 9h, and the reaction is completed to obtain LiMnPO 4 Precursor, according to Li + with Mn 2+ Weigh Li with a molar ratio of 1.02:1 3 PO 4 with Mn 3 (PO 4 ) 2 ;
  • the particle size D50 of the positive electrode material is 3.2 ⁇ m, and the porosity of the inner core area and the outer shell area are 80% and 28%, respectively, according to the porosity tester.
  • the binary solution includes MnC 2 O 4 and (NH 4 )H 2 PO 4 , the molar concentration of the binary solution is 1.5mol/L, and the molar ratio of PO 4 3- to Mn 2+ in the system is 1.05:1;
  • the reaction solution is prepared and stirred, and the reaction solution is a mixed solvent of polyethylene glycol 200 and water with a volume ratio of 1:1; citric acid solution The concentration is 2.0mol/L; the concentration of carbonic acid solution is 0.1mol/L;
  • Stage 1 inject the above mixed solution into the reactor, control the stirring speed at 550rpm, control the concentration of citric acid solution at 0.04mol/L, and control the pH value of the solution at 1.6 to form an intermediate reaction solution.
  • the co-precipitation reaction time of stage 1 is 15h. This process is the nucleation and core growth stage of the precursor, and the precursor crystal nucleus is obtained;
  • Stage 2 inject citric acid solution and carbonic acid solution into the precursor crystal nucleus solution obtained in the above steps, adjust the pH value of the system to 2.8, control the concentration of complexing agent at 0.3mol/L, and carry out co-precipitation reaction at a stirring rate of 420rpm .
  • Composed of dense large particles, the particle composition of the core area and the outer shell area are both Mn 3 (PO 4 ) 2 ;
  • Phosphoric acid solution is added to LiOH solution for reaction to form the Li 3 PO 4 crystal solution;
  • the phosphoric acid solution is an aqueous phosphoric acid solution, and its molar concentration is 1.5mol/L;
  • the LiOH solution is an aqueous LiOH solution, and its molar concentration is 1.75mol/L, and Li in the system + with PO 4 3- Molar ratio is 0.98:1;
  • the Mn 3 (PO 4 ) 2 The precursor is uniformly dispersed to the Li 3 PO 4
  • the crystal nucleation is grown in the crystal solution, the crystal nucleation reaction time is 6h, and LiMnPO is obtained at the end of the reaction.
  • 4 Precursor, according to Li + with Mn 2+ Weigh Li with a molar ratio of 1.04:1 3 PO 4 with Mn 3 (PO 4 ) 2 ;
  • the particle size D50 of the positive electrode material is 4.0 ⁇ m, and the porosity of the core area and the outer shell area are 82% and 31%, respectively, as tested by a porosity tester.
  • the binary solution includes (CH 3 COO) 2 Mn and (NH 4 ) 2 HPO 4 , the molar concentration of the binary solution is 2.5mol/L, and the molar ratio of PO 4 3- and Mn 2+ in the system is 1:1.
  • the reaction solution is prepared and stirred.
  • the reaction solution is a mixed solvent of polyethylene glycol 400 and water with a volume ratio of 1:1; EDTA solution is 1.8mol/L; the concentration of acetic acid solution is 0.2mol/L;
  • Stage 1 inject the above mixed solution into the reactor, control the stirring speed at 500rpm, control the concentration of EDTA solution at 0.04mol/L, and control the pH value of the solution at 2.0 to form an intermediate reaction solution.
  • the co-precipitation reaction time of stage 1 is 10h. This process is the nucleation and core growth stage of the precursor, and the precursor crystal nucleus is obtained;
  • Stage 2 Inject EDTA solution and acetic acid solution into the precursor crystal nucleus solution obtained in the above steps, adjust the pH value of the system to 3.0, control the concentration of complexing agent at 0.25mol/L, and carry out co-precipitation reaction at a stirring rate of 450rpm.
  • This stage is the shell production stage of the precursor. The reaction is terminated after the target particle size reaches 3.2 ⁇ m, and the Mn 3 (PO 4 ) 2 precursor is obtained; the core area of the precursor is composed of agglomerated and loose particles, and the shell area Composed of agglomerated and dense large particles, the particles in the inner core area and the outer shell area are composed of Mn 3 (PO 4 ) 2 ;
  • Phosphoric acid solution is added to LiOH solution for reaction to form the Li 3 PO 4 crystal solution;
  • the phosphoric acid solution is an aqueous phosphoric acid solution, and its molar concentration is 1.25mol/L;
  • the LiOH solution is an aqueous LiOH solution, and its molar concentration is 2.0mol/L, and Li in the system + with PO 4 3-
  • the molar ratio is 1:1;
  • the precursor is uniformly dispersed to Li 3 PO 4
  • the crystal nucleation is grown in the crystal solution, the crystal nucleation reaction time is 8h, and LiMnPO is obtained at the end of the reaction.
  • 4 Precursor, according to Li + with Mn 2+ Weigh Li with a molar ratio of 1.02:1 3 PO 4 with Mn 3 (PO 4 ) 2 ;
  • Glucose and LiMnPO 4 precursors were mixed according to the mass ratio of 0.12:1, and high-temperature roasting was carried out under an inert atmosphere.
  • multi-stage temperature-controlled sintering was adopted, and the heating rate was increased from room temperature to 580 °C at a rate of 3 °C/ min .
  • the temperature was kept at 580 °C for 6 hours, and then the temperature was raised to 720 °C for 10 hours.
  • C wherein, the carbon content measured by the carbon-sulfur meter is 2.0% (mass ratio), and the specific surface area (BET value) is shown in Table 1.
  • the particle size D50 of the positive electrode material is 3.4 ⁇ m, and the porosity of the core area and the outer shell area are 76% and 25%, respectively, as tested by a porosity tester.
  • the binary solution includes MnC 2 O 4 and H 3 PO 4 , the molar concentration of the binary solution is 1.2mol/L, and the molar ratio of PO 4 3- and Mn 2+ in the system is 1.02:1;
  • the reaction solution is prepared and stirred, and the reaction solution is a mixed solvent of ethylene glycol and water with a volume ratio of 3:1; wherein the concentration of the citric acid solution is 2.0mol/L, The concentration of oxalic acid solution is 0.15mol/L;
  • the above mixed solution was injected into the reactor, and the pH value of the system was adjusted to 2.2 by fine-tuning the amount of oxalic acid solution added.
  • the concentration of the complexing agent was controlled at 0.12mol/L, and the co-precipitation reaction was carried out at a stirring rate of 450rpm until the target particle size reached 4.5 ⁇ m. After the reaction was terminated, the Mn 3 (PO 4 ) 2 precursor was obtained;
  • Phosphoric acid solution is added to LiOH solution for reaction to form the Li 3 PO 4 crystal solution;
  • the phosphoric acid solution is an aqueous phosphoric acid solution, and its molar concentration is 1.0mol/L;
  • the LiOH solution is an aqueous LiOH solution, and its molar concentration is 1.5mol/L, and Li in the system + with PO 4 3-
  • the molar ratio is 1.02:1;
  • the Mn 3 (PO 4 ) 2 The precursor is uniformly dispersed to the Li 3 PO 4
  • the crystal nucleus grows in the crystal solution, the reaction time of the crystal nucleus is 10h, and LiMnPO is obtained at the end of the reaction.
  • 4 Precursor, according to Li + with Mn 2+ Weigh Li with a molar ratio of 1.05:1 3 PO 4 with Mn 3 (PO 4 ) 2 ;
  • the particle size D50 of the positive electrode material is 4.6 ⁇ m, and the porosity of the positive electrode active material LiMnPO 4 is 28% as tested by a porosity tester.
  • the positive electrode material prepared in Comparative Example 1 is a secondary spherical structure formed by the close packing of primary particles, which is a solid spherical particle, and there is no hollow or agglomerated loose structure.
  • the positive electrode material of Comparative Example 1 has a lower porosity.
  • the small particles on the surface in Figure 4 are caused by vacuuming during electron microscope shooting.
  • Embodiment 5-12 and comparative example 2 are identical to Embodiment 5-12 and comparative example 2
  • the ternary solution includes FeSO 4 , MnSO 4 and H 3 PO 4 , the total molar concentration of the ternary solution is 1.5mol/L, the molar ratio of Fe 2+ to Mn 2+ is 2:8, and the molar ratio of the sum of (Fe 2+ +Mn 2+ ) to PO 4 3- is 3:2; the reaction solution is prepared and stirred, and the reaction solution is ethylene glycol
  • Stage 1 inject the above mixed solution into the reactor, and control the stirring speed at 400rpm to form an intermediate reaction solution, wherein the concentration of the oxalic acid solution is controlled at 0.025mol/L, the pH value of the solution is adjusted at 1.8, and the co-precipitation reaction time of stage 1 is 12h.
  • This process is the nucleation of the precursor and the core growth stage, and a solution containing the crystal nucleus of the precursor is obtained.
  • the particle size D50 of the crystal nucleus is 2.6 ⁇ m;
  • Stage 2 inject the above-mentioned oxalic acid solution and acetic acid solution into the solution containing the precursor crystal nucleus obtained in the above-mentioned stage 1, adjust the pH value of the system to 2.6, control the concentration of the complexing agent at 0.15mol/L, and carry out coprecipitation reaction at a stirring rate of 300rpm.
  • This stage is the shell production stage of the precursor, and the reaction is terminated until the target particle size D50 reaches 5.5 ⁇ m, and the reaction is obtained (Fe 0.2 mn 0.8 ) 3 (PO 4 ) 2 Precursor;
  • the core area of the precursor is composed of agglomerated and loose micro-particles formed by the above-mentioned crystal nucleus, and the outer shell area is composed of agglomerated and dense large particles, and the particles in the inner core area and the outer shell area are composed of (Fe 0.2 mn 0.8 ) 3 (PO 4 ) 2 ;
  • step (3) The slurry after the reaction in step (2) is subjected to solid-liquid separation, aging, drying, grinding, screening and impurity removal to obtain a (Fe 0.2 Mn 0.8 ) 3 (PO 4 ) 2 precursor;
  • Figure 5 is the XRD pattern of the lithium manganese iron phosphate positive electrode material in Example 5, it can be seen that the prepared material is a solid solution material, and the PDF card matching result is lithium manganese iron phosphate.
  • Example 6 is an SEM image of the lithium manganese iron phosphate positive electrode material of Example 5; it can be seen from the figure that the prepared spherical particles are 4 ⁇ m to 5 ⁇ m in size.
  • Fig. 7 is a particle cross-sectional SEM image of the positive electrode material of Example 5. It can be seen that the core area of the positive electrode material is composed of agglomerated loose particles, the shell area is composed of agglomerated dense particles, and the core area is a loose structure, and part of it is a hollow structure.
  • Fig. 8 is the nitrogen adsorption-desorption curve of the lithium manganese iron phosphate positive electrode material in Example 5; it can be seen from the figure that the curve has obvious stagnant rings, and the prepared material has a mesoporous structure.
  • Assembling the button battery Weigh and mix the above-mentioned positive electrode material, conductive agent acetylene black, and binder PVDF according to a mass ratio of 90:5:5, and disperse with N-methylpyrrolidone (NMP) solvent to form a slurry; the slurry is evenly coated on an aluminum foil sheet and dried at 80°C for 12 hours to obtain a positive electrode sheet.
  • the assembly of the lithium-ion battery must be carried out in a glove box using argon as a protective gas.
  • the positive electrode sheet includes: positive electrode material, conductive agent (conductive carbon black + carbon nanotubes, mass ratio 1.5:0.5) and binder PVDF are uniformly mixed at a mass ratio of 96.5:2:1.5.
  • the solvent is N-methylpyrrolidone NMP and stirred evenly.
  • the positive electrode current collector is (10+2) ⁇ m carbon-coated aluminum foil; the pole piece is baked at a high temperature, rolled into a sheet, and cut into a positive pole piece for later use.
  • Negative electrode sheet includes: artificial graphite, conductive agent acetylene black, carboxymethylcellulose sodium CMC and binder LA133 are uniformly mixed at a mass ratio of 96.5:1:1:1.5.
  • the solvent is deionized water, stirred evenly to prepare a slurry, and then coated on a copper foil current collector.
  • the negative electrode current collector is 6 ⁇ m copper foil; and cut into negative electrode sheets for later use.
  • ternary solution Separately configure ternary solution, citric acid solution and carbonic acid solution for use, wherein the ternary solution includes FeC 2 O 4 , MnC 2 O 4 and (NH 4 )H 2 PO 4 , the total molar concentration of the ternary solution is 1.25mol/L, the molar ratio of Fe 2+ to Mn 2+ is 3:7, and the molar ratio of the sum of (Fe 2+ +Mn 2+ ) to PO 4 3- is 3.1 5:2; configure the reaction solution and stir, the reaction solution is a mixed solvent of polyethylene glycol 400 and water with a volume ratio of 2:1; the concentration of the citric acid solution is 1.5mol/L; the concentration of the carbonic acid solution is 0.1mol/L;
  • Stage 1 inject the above mixed solution into the reactor, control the stirring speed at 500rpm, control the concentration of citric acid solution at 0.03mol/L, and control the pH value of the solution at 1.7 to form an intermediate reaction solution.
  • the co-precipitation reaction time of stage 1 is 10h. This process is the nucleation of the precursor and the core growth stage, and a solution containing the precursor crystal nucleus is obtained.
  • the particle size D50 of the crystal nucleus is 2.5 ⁇ m;
  • Stage 2 inject citric acid solution and carbonic acid solution into the precursor crystal nucleus solution obtained in the above stage 1, adjust the pH value of the system to 2.6, control the concentration of complexing agent at 0.2mol/L, and carry out coprecipitation reaction at a stirring rate of 400rpm.
  • This stage is the shell production stage of the precursor, and the reaction is terminated until the target particle size D50 reaches 4.8 ⁇ m, and the reaction is obtained (Fe 0.3 mn 0.7 ) 3 (PO 4 ) 2 Precursor;
  • the core area of the precursor is composed of agglomerated and loose tiny particles,
  • the shell area is composed of agglomerated dense large particles, and the particles in the core area and the shell area are composed of (Fe 0.3 mn 0.7 ) 3 (PO 4 ) 2 ;
  • the ternary solution includes (CH 3 COO) 2 Fe, (CH 3 COO ) 2 Mn and ( NH 4 ) 2 HPO 4 .
  • the molar ratio is 3.06:2; the reaction solution is configured and stirred, and the reaction solution is a mixed solvent with a volume ratio of ethylene glycol and water of 2:1; the concentration of the citric acid solution is 1.75mol/L; the concentration of the acetic acid solution is 0.25mol/L;
  • Stage 1 inject the above mixed solution into the reactor, control the stirring speed at 450rpm, control the concentration of citric acid solution at 0.035mol/L, and control the pH value of the solution at 2.0 to form an intermediate reaction solution.
  • the co-precipitation reaction time of stage 1 is 10h. This process is the nucleation of the precursor and the core growth stage, and a solution containing the crystal nucleus of the precursor is obtained.
  • the particle size D50 of the crystal nucleus is 2.6 ⁇ m;
  • Stage 2 inject citric acid solution and acetic acid solution into the precursor crystal nucleus solution obtained in the above steps, adjust the pH value of the system to 2.8, control the concentration of complexing agent at 0.15mol/L, and carry out coprecipitation reaction at a stirring rate of 400rpm.
  • This stage is the shell production stage of the precursor, and the reaction is terminated until the target particle size D50 reaches 5.8 ⁇ m, and the reaction is obtained (Fe 0.4 mn 0.6 ) 3 (PO 4 ) 2 Precursor;
  • the core area of the precursor is composed of agglomerated and loose tiny particles,
  • the shell area is composed of agglomerated dense large particles, and the particles in the core area and the shell area are composed of (Fe 0.4 mn 0.6 ) 3 (PO 4 ) 2 ;
  • the ternary solution includes FeCl 2 , MnSO 4 and H 3 PO 4 , the total molar concentration of the ternary solution is 1.25mol/L, the molar ratio of Fe 2+ to Mn 2+ is 2:8, and the molar ratio of the sum of (Fe 2+ +Mn 2+ ) to PO 4 3- is 3.1:2; the reaction solution is prepared and stirred, and the reaction solution is poly
  • the mixed solvent of ethylene glycol 200 and water volume ratio is 2:1; the concentration of citric acid solution is 2.25mol/L; the concentration of carbonic acid solution is 0.2mol/L;
  • Stage 1 inject the above mixed solution into the reactor, control the stirring speed at 450rpm, control the concentration of citric acid solution at 0.025mol/L, and control the pH value of the solution at 2.2 to form an intermediate reaction solution.
  • the co-precipitation reaction time of stage 1 is 15h. This process is the nucleation of the precursor and the core growth stage, and a solution containing the crystal nucleus of the precursor is obtained.
  • the particle size D50 of the crystal nucleus is 2.75 ⁇ m;
  • Stage 2 inject citric acid solution and carbonic acid solution into the precursor crystal nucleus solution obtained in the above steps, adjust the pH value of the system to 2.8, control the concentration of complexing agent at 0.2mol/L, and carry out co-precipitation reaction at a stirring rate of 400rpm.
  • This stage is the shell production stage of the precursor, and the reaction is terminated until the target particle size D50 reaches 6.0 ⁇ m, and the reaction is obtained (Fe 0.2 mn 0.8 ) 3 (PO 4 ) 2 Precursor;
  • the core area of the precursor is composed of agglomerated and loose tiny particles, the shell area is composed of agglomerated dense large particles, and the particles in the core area and the shell area are composed of (Fe 0.2 mn 0.8 ) 3 (PO 4 ) 2 ;
  • the ternary solution includes FeSO 4 , MnSO 4 and H 3 PO 4 , the total molar concentration of the ternary solution is 1.25mol/L, Fe 2+ with Mn 2+ The molar ratio is 2.5:7.5, (Fe 2+ +Mn 2+ ) and PO 4 3- The molar ratio is 3.06:2; the blending solution includes VCl 5 and NbCl 5 , V 5+ with Nb 5+ The molar ratio is 1:2; the reaction solution is configured and stirred, and the reaction solution is a mixed solvent of ethylene glycol and water with a volume ratio of 2:1; the concentration of the oxalic acid solution is 1.5mol/L, and the concentration of the carbonic acid solution is 0.125mol/L;
  • Stage 1 inject the above mixed solution into the reactor, control the stirring speed at 450rpm, control the concentration of oxalic acid solution at 0.025mol/L, and control the pH value of the solution at 1.6 to form an intermediate reaction solution.
  • the co-precipitation reaction time of stage 1 is 15h. This process is the nucleation and core growth stage of the precursor, and a solution containing the crystal nucleus of the precursor is obtained.
  • the particle size D50 of the crystal nucleus is 2.5 ⁇ m;
  • Stage 2 Inject oxalic acid solution and carbonic acid solution into the solution containing precursor crystal nuclei obtained in the above steps, adjust the pH value of the system to 2.8, control the concentration of complexing agent at 0.15mol/L, and carry out co-precipitation reaction at a stirring rate of 400rpm.
  • Composition of large particles, the composition of particles in the inner core area and the outer shell area is the same;
  • step (3) The slurry after the reaction in step (2) is subjected to solid-liquid separation, aging, drying, grinding, screening and impurity removal to obtain a co-doped precursor;
  • Fig. 9 is an SEM image of the particle profile of the positive electrode material of Example 9. It can be seen from Fig. 9 that the core region of the positive electrode material is composed of agglomerated loose tiny particles, the outer shell region is composed of agglomerated dense large particles, and the core region is a loose structure, and part of it is a hollow structure.
  • Figure 10 is the XRD pattern of the lithium manganese iron phosphate positive electrode material prepared by the co-doping method in Example 9; it can be seen from Figure 10 that with the addition of doping elements, the position and relative intensity of the diffraction peaks do not change significantly, indicating that the doping elements in the positive electrode material of Example 9 are successfully embedded in the lattice structure, and a pure solid solution is formed.
  • reaction solution is configured and stirred, and the reaction solution is a mixed solvent of polyethylene glycol 200 and water volume ratio of 2:1; the concentration of the citric acid solution is 1.75mol/L, and the concentration of the acetic acid solution is 0.1mol/L;
  • Stage 1 inject the above mixed solution into the reactor, control the stirring speed at 500rpm, control the concentration of citric acid solution at 0.025mol/L, and control the pH value of the solution at 1.8 to form an intermediate reaction solution.
  • the co-precipitation reaction time of stage 1 is 12h. This process is the nucleation of the precursor and the core growth stage, and a solution containing the crystal nucleus of the precursor is obtained.
  • the particle size D50 of the crystal nucleus is 2.2 ⁇ m;
  • Stage 2 inject citric acid solution and acetic acid solution into the precursor crystal nucleus solution obtained in the above steps, adjust the pH value of the system to 3.0, control the concentration of complexing agent at 0.175mol/L, and carry out co-precipitation reaction at a stirring rate of 400rpm.
  • Composition of large particles, the composition of particles in the inner core area and outer shell area is the same.
  • Stage 1 inject the above mixed solution into the reactor, control the stirring speed at 400rpm, control the concentration of oxalic acid solution at 0.03mol/L, and control the pH value of the solution at 2.0 to form an intermediate reaction solution.
  • the co-precipitation reaction time of stage 1 is 12h. This process is the nucleation of the precursor and the core growth stage, and a solution containing the crystal nucleus of the precursor is obtained.
  • the particle size D50 of the crystal nucleus is 2.4 ⁇ m;
  • Stage 2 Inject oxalic acid solution and acetic acid solution into the precursor crystal nucleus solution obtained in the above steps, adjust the pH value of the system to 3.2, control the concentration of complexing agent at 0.2mol/L, and carry out co-precipitation reaction at a stirring rate of 350rpm.
  • This stage is the shell production stage of the precursor, and the reaction is terminated until the target particle size D50 reaches 3.5 ⁇ m to obtain a doped precursor;
  • the composition of the particles in the core area and the outer shell area is the same.
  • Reaction stage 1 inject the above mixed solution into the reactor, control the stirring speed at 450rpm, control the concentration of citric acid solution at 0.025mol/L, and control the pH value of the solution at 1.8 to form an intermediate reaction solution.
  • the co-precipitation reaction time of stage 1 is 12h. This process is the nucleation of the precursor and the core growth stage, and a solution containing the crystal nucleus of the precursor is obtained.
  • the particle size D50 of the crystal nucleus is 2.6 ⁇ m;
  • Reaction stage 2 inject citric acid solution and acetic acid solution into the precursor crystal nucleus solution obtained in the above steps, adjust the pH value of the system to 2.8, control the concentration of complexing agent at 0.2mol/L, and carry out co-precipitation reaction at a stirring rate of 400rpm.
  • Particle composition, the composition of particles in the inner core area and the outer shell area is the same.
  • ternary solution Separately configure ternary solution, oxalic acid solution and carbonic acid solution for use, wherein the ternary solution includes (CH 3 COO) 2 Fe, MnC 2 O 4 and H 3 PO 4 , the total molar concentration of the ternary solution is 1.5mol/L, the molar ratio of Fe 2+ to Mn 2+ is 3:7, and the molar ratio of the sum of (Fe 2+ +Mn 2+ ) to PO 4 3- is 3.15:2; configuration
  • the reaction solution is stirred, and the reaction solution is a mixed solvent of polyethylene glycol 200 and water with a volume ratio of 2:1; the concentration of the oxalic acid solution is 2.0mol/L, and the concentration of the carbonic acid solution is 0.15mol/L;
  • the above mixed solution was injected into the reactor, the pH value of the system was adjusted to 2.6 by fine-tuning the amount of carbonic acid solution added, the concentration of the complexing agent was controlled at 0.15 mol/L, and the co-precipitation reaction was carried out at a stirring rate of 400 rpm until the target particle size D50 reached 6.0 ⁇ m and then the reaction was terminated to obtain the (Fe 0.3 Mn 0.7 ) 3 (PO 4 ) 2 precursor;
  • the temperature was raised from room temperature to 560°C, first kept at 580°C for 5 hours, then raised to 700°C for 8 hours, and the sample was naturally cooled to room temperature to obtain LiFe 0.3 Mn 0.7 PO 4 /C with a carbon-coated structure.
  • the carbon content measured by the carbon-sulfur meter was 1.6% (mass ratio), and the specific surface area (BET value) is shown in Table 1.
  • FIG. 11 is a SEM cross-sectional view of the lithium manganese iron phosphate positive electrode material of Comparative Example 2. It can be seen from the figure that the particles prepared in Comparative Example 2 are solid spherical particles. As can be seen from the particle cross-section SEM image of the positive electrode material of Example 5 shown in Figure 7, the core area of the positive electrode material of Example 5 is composed of agglomerated loose particles, the shell area is composed of agglomerated dense particles, and the core area contains a hollow structure.
  • Reaction stage 1 inject the above mixed solution into the reactor, control the stirring speed at 450rpm, control the concentration of citric acid solution at 0.025mol/L, and control the pH value of the solution at 1.8 to form an intermediate reaction solution.
  • the co-precipitation reaction time of stage 1 is 12h. This process is the nucleation of the precursor and the core growth stage, and a solution containing the crystal nucleus of the precursor is obtained.
  • the particle size D50 of the crystal nucleus is 2.6 ⁇ m;
  • Reaction stage 2 inject citric acid solution and acetic acid solution into the precursor crystal nucleus solution obtained in the above steps, adjust the pH value of the system to 2.8, control the concentration of complexing agent at 0.2mol/L, and carry out co-precipitation reaction at a stirring rate of 400rpm.
  • Particle composition, the composition of particles in the inner core area and outer shell area is the same;
  • the button batteries of Examples 1-12 and Comparative Examples 1-2 were tested for charging performance at a temperature of 25 ⁇ 5°C, and the test process was as follows:
  • Example 13 was carried out with reference to the above test process, except that the upper limit voltage in step 2) was changed from 4.5V to 3.65V.
  • Figure 12 is the button battery charging and discharging curve of embodiment 1;
  • Figure 13 is the charging and discharging curve of the button battery of comparative example 1;
  • Figure 14 is the button battery charging and discharging curve of embodiment 5;
  • Figure 15 is the charging and discharging curve of the button battery of comparative example 2;
  • Figure 16 is the charging and discharging curve of embodiment 9.
  • the rate performance test of the pouch batteries of Examples 1-12 and Comparative Example 1-2 was performed at a temperature of 25 ⁇ 2°C, and the test process was as follows:
  • Example 13 was carried out with reference to the above test process, except that the upper limit voltage in step 4) was changed from 4.5V to 3.65V.
  • the test process includes:
  • the battery cell is placed in an environment of 25°C ⁇ 2°C (45°C ⁇ 2°C);
  • Example 13 was carried out with reference to the above test process, except that the voltage range was changed from 2.5V to 4.5V to 2.5V to 3.65V.
  • Figure 19 is the cycle capacity retention rate of the soft-packed cell of Example 1 at 25°C;
  • Figure 20 is the cycle capacity retention rate of the soft-packed cell of Example 1 at 45°C;
  • Figure 18 is the cycle capacity retention rate of Example 9 at 45°C.
  • the soft-packed cells of Examples 1-12 and Comparative Examples 1-2 were fully charged to 4.5V at a rate of 0.33C, and the positive electrode sheet (without the positive electrode current collector) was disassembled and recovered in an argon-filled glove box, and the above-mentioned positive electrode sheet was rinsed with dimethyl carbonate (DMC) and dried.
  • DMC dimethyl carbonate
  • the positive electrode sheet and the electrolyte solution were added according to 1mg:0.6 ⁇ L.
  • the thermal analysis test temperature range was 25°C-500°C, and the heating rate was 5°C/min.
  • Example 13 was carried out with reference to the above test process, except that the battery was fully charged to 3.65V at a rate of 0.33C, and the test results are shown in Table 1.
  • Electrochemical alternating current impedance (EIS) measurement was carried out on Shanghai Chenhua CHI600E electrochemical workstation.
  • the pouch cells of Examples 1-12 and Comparative Example 1-2 were tested, and the battery state was adjusted to 50% SOC state; the voltage window was set to 2.5V-4.5V, the amplitude was 5mV, and the frequency range was 10-2-105 Hz .
  • Example 13 was carried out with reference to the above test process, except that the voltage window was changed from 2.5V to 4.5V to 2.5V to 3.65V.
  • FIG. 21 is an impedance diagram of Example 9.
  • the test results are shown in Table 1.
  • Discharge temperature 25°C/45°C/0°C/-10°C/-20°C.
  • the positive electrode material sample powder prepared in Examples 1-4 and Comparative Example 1 was mixed with 5% PVDF, and pressed into a cylindrical sheet ( ⁇ 10.0mm) with a tablet press, and the electronic conductivity of the LiMnPO 4 /C sample was tested using a four-probe direct current technique.
  • the test results are shown in Table 3.
  • the positive electrode materials prepared in Examples 1-4 and Comparative Example 1 were tested for lithium ion diffusion coefficient (D Li + ) by galvanostatic intermittent titration (GITT method).
  • Example 13 was carried out with reference to the above test process, except that the upper limit voltage in step 2) was changed from 4.5V to 3.65V.
  • the metal Li negative electrode has little influence on the battery voltage change.
  • the voltage change during the test mainly comes from the positive electrode material, and the diffusion coefficient obtained by this method mainly reflects the diffusion coefficient of the positive electrode material.
  • the positive electrode materials of Examples 1 to 13 prepared by the preparation method of the present disclosure have a loosely aggregated inner core and a densely aggregated outer shell (as shown in FIG. 3 , FIG. 7 and FIG. 9 ).
  • the positive electrode materials in Examples 1 to 4 have particles with smaller particle sizes and a special core-shell structure, so that the material has better lithium ion diffusion capacity and electronic conductivity, and the material has better kinetic performance; when the above positive electrode material is used to prepare a positive electrode sheet and applied to the lithium battery level, it has better kinetic performance and rate discharge capability, and at the same time, the low temperature discharge performance and safety performance have also been significantly improved.
  • the positive electrode materials prepared in Examples 1 to 13 all have agglomerated loose inner core and dense outer shell, and the central position of the inner core area has an agglomerated loose structure, and further, the central position of the inner core area is hollow.
  • the positive electrode material has a schematic structure as shown in FIG. 1 .
  • microspheres with the core-shell structure are beneficial to improve the wetting effect of the electrolyte and the electronic conductivity of the material.
  • the internal loose structure shortens the diffusion distance of lithium ions, and the rate performance and long-term cycle performance of the material are significantly improved.
  • the positive electrode sheets prepared by using the positive electrode materials in Examples 5-12 have excellent long-term cycle performance, low internal resistance and high output power when applied to lithium-ion batteries. Therefore, the positive electrode materials disclosed in the present disclosure are suitable for batteries with high safety performance requirements.
  • the positive electrode materials of Examples 9-12 form an effective synergistic effect through the doping of vanadium and niobium dual elements, and the electronic conductivity and lithium ion diffusion rate of lithium iron manganese phosphate are also significantly improved, and the discharge gram capacity of the material is increased.
  • the positive electrode materials of Examples 9-12 are used as the positive electrode of the battery, and the rate performance of the battery is better.
  • co-doping can also improve the high temperature resistance of the positive electrode material. Therefore, the battery using the positive electrode material of the present disclosure as the positive electrode has significantly improved cycle stability at room temperature and high temperature, and has high safety performance, low internal resistance, and high output power. Therefore, the positive electrode material of the present disclosure is suitable for batteries that require high safety performance.

Abstract

本公开提供一种正极材料及包括该材料的正极片和电池。所述正极材料包括正极活性材料和在所述正极活性材料表面的包覆材料；所述正极材料的中值粒径D50为2μm～7μm；所述正极活性材料的化学式为LiaFexMn1-x-y-zMyNzPO4，其中M和N为共掺杂元素，0.9≤a≤1.1，0≤x≤1，0≤y≤0.02，0≤z≤0.02。所述正极材料的中值粒径D50为2μm～7μm，可以获得具备较优的动力学性能、低温放电性能和高安全性能的电池。

Description

一种正极材料及包括该材料的正极片和电池 技术领域
本公开属于电池技术领域，涉及一种正极材料及包括该材料的正极片和电池。
发明背景
电池在便携式电器和动力储能系统等方面得到应用推广，实现了手机、笔记本电脑以及数码相机的无线革命，是当今社会所需便携式电器和电信设备的关键组件。正极材料作为电池的重要组成部分，与电池的性能息息相关。
常规的橄榄石型正极材料具有较低的电子电导率和锂离子扩散系数，倍率性能和低温性能短板显著，影响电池性能，且制备工艺复杂，限制了其规模化生产。
发明内容
为克服上述背景技术中提到的不足与缺陷，本公开提供一种正极材料及其制备方法、包括该正极材料的正极片和包括该正极片的电池，所述正极材料的中值粒径选择在一定范围，可以获得具备较优的动力学性能、低温放电性能和高安全性能的电池。
本公开提出的技术方案如下：
一种正极材料，所述正极材料包括正极活性材料和在所述正极活性材料表面的包覆材料；所述正极材料的中值粒径D50为2μm～7μm，例如，所述正极材料的中值粒径D50为2μm、3μm、4μm、5μm、6μm、7μm或上述两两端点组成的范围中的任意点值；
所述正极活性材料的化学式为LiaFexMn1-x-y-zMyNzPO4，其中M和N为共掺杂元素，0.9≤a≤1.1(例如a＝0.9、0.91、0.92、0.93、0.94、0.95、0.96、0.97、0.98、0.99、1、1.01、1.02、1.03、1.04、1.05、1.06、1.07、1.08、1.09、1.1或上述两两端点组成的范围中的任意点值)，0≤x≤1(例如x＝0、0.1、0.2、0.3、0.4、0.5、0.6、0.7、0.8、0.9、1或上述两两端点组成的范围中的任意点值)，0≤y≤0.02(例如y＝0、0.001、0.002、0.003、0.004、0.005、0.006、0.007、0.008、0.009、0.01、0.011、0.012、0.013、0.014、0.015、0.016、0.017、0.018、0.019、0.02或上述两两端点组成的范围中的任意点值)，0≤z≤0.02(例如z＝0、0.001、0.002、0.003、0.004、0.005、0.006、0.007、0.008、0.009、0.01、0.011、0.012、0.013、0.014、0.015、0.016、0.017、0.018、0.019、0.02或上述两两端点组成的范围中的任意点值)。
根据本公开的实施方案，0.96≤a≤1.1。
根据本公开的实施方案，所述M选自铌(Nb)、镁(Mg)、钴(Co)、锌(Zn)、镍(Ni)或铜(Cu)中的至少一种，例如为铌(Nb)。
根据本公开的实施方案，所述N选自铝(Al)、钛(Ti)、钒(V)或铈(Ce)中的至少一种，例如为钒(V)。
根据本公开的实施方案，所述正极活性材料具有橄榄石型结构。
根据本公开的实施方案，所述正极活性材料为二次球形颗粒，所述二次球形颗粒包括内核区域和外壳区域，所述外壳区域位于所述内核区域的外层；所述外壳区域具有团聚密实结构；所述内核区域具有团聚疏松结构。
研究发现，中空结构可以为锂离子的扩散提供多种路径，解决了现有技术中正极材料的锂扩散速度低和极化等问题，同时也使得包括该正极材料的正极片和包括该正极片的电池具有良好的倍率性能和动力学性能，尤其具有良好的低温放电性能。
根据本公开的实施方案，所述包覆材料包括碳材料。优选地，所述碳材料包括不定形碳。
根据本公开的实施方案，所述包覆材料的厚度为2nm～10nm，例如为2nm、3nm、4nm、5nm、6nm、7nm、8nm、9nm、10nm或上述两两端点组成的范围中的任意点值。
如图22所示，为本公开一实例中所述正极活性材料的TEM谱图，图中右下角所标示的“Carbon”的厚度为所述包覆材料的厚度。
根据本公开的实施方式，所述正极材料的比表面积为8m2/g～25m2/g，例如8m2/g、9m2/g、10m2/g、11m2/g、12m2/g、13m2/g、14m2/g、15m2/g、16m2/g、17m2/g、18m2/g、19m2/g、20m2/g、21m2/g、22m2/g、23m2/g、24m2/g、25m2/g或上述两两端点组成的范围中的任意点值。
根据本公开的实施方案，所述正极活性材料的化学式为LiaMn1-y-zMyNzPO4。
根据本公开的实施方案，所述正极活性材料的化学式为LiMnPO4。
根据本公开的实施方案，所述正极活性材料为磷酸锰锂。
根据本公开的实施方案，所述正极材料的中值粒径D50为2μm～5μm。
根据本公开的实施方案，所述外壳区域具有孔隙。示例性地，所述外壳区域的孔隙率为10％～35％，例如为10％、12％、15％、18％、20％、22％、25％、28％、30％、32％、35％或上述两两端点组成的范围中的任意点值。
根据本公开的实施方案，所述内核区域的孔隙率大于所述外壳区域的孔隙率。示例性地，所述内核区域的孔隙率为60％～90％，例如为60％、62％、65％、68％、70％、72％、75％、78％、80％、82％、85％、88％、90％或上述两两端点组成的范围中的任意点值。
本公开对孔隙率的测试方法不做具体限定，可采用本技术领域已知的方法测得。
根据本公开的实施方案，所述包覆材料的厚度为2nm～8nm。
根据本公开的实施方案，所述正极材料的比表面积为15m2/g～25m2/g，例如15m2/g、16m2/g、17m2/g、18m2/g、19m2/g、20m2/g、21m2/g、22m2/g、23m2/g、24m2/g、25m2/g或上述两两端点组成的范围中的任意点值。。
根据本公开的实施方案，所述正极材料的电子电导率为1.0×10-5S/cm～9.0×10-5S/cm。
根据本公开的实施方案，所述正极材料的锂离子扩散系数为1.0×10-14cm2/s～8.0×10-14cm2/s。
根据本公开的实施方案，所述正极活性材料的质量占所述正极材料总质量的97.5wt％～99.0wt％，例如为97.5wt％、98wt％、98.5wt％、99wt％或上述两两端点组成的范围中的任意点值。
根据本公开的实施方案，所述包覆材料的质量占所述正极材料总质量的1wt％～2.5wt％，例如为1wt％、1.5wt％、2wt％、2.5wt％或上述两两端点组成的范围中的任意点值。
根据本公开的实施方案，所述正极活性材料的内核区域的中值粒径D50为1.2μm～2.6μm，例如1.2μm、1.3μm、1.4μm、1.5μm、1.6μm、1.7μm、1.8μm、1.9μm、2μm、2.1μm、2.2μm、2.3μm、2.4μm、2.5μm、2.6μm或上述两两端点组成的范围中的任意点值。
根据本公开的实施方案，所述内核区域和所述外壳区域的组成相同，均为磷酸锰锂LiMnPO4。
根据本公开的实施方案，所述二次球形颗粒是指由磷酸锰锂一次颗粒堆积形成的球形的二次颗粒结构。
根据本公开的实施方案，所述内核区域是由小粒径(200nm-300nm)的磷酸锰锂一次颗粒团聚形成，所述的内核区域是孔隙率为60％～90％的团聚疏松结构。
根据本公开的实施方案，所述外壳区域是由大粒径(300nm-500nm)的磷酸锰锂一次颗粒团聚形成，所述的外壳区域是孔隙率为10％～35％的团聚密实结构。
根据本公开的实施方案，所述正极活性材料的化学式为LiaFexMyNzPO4。
根据本公开的实施方案，所述正极活性材料的化学式为LiFePO4。
根据本公开的实施方案，所述正极活性材料为磷酸铁锂。
根据本公开的实施方案，所述外壳区域具有孔隙。示例性地，所述外壳区域的孔隙率为10％～35％，例如为10％、12％、15％、18％、20％、22％、25％、28％、30％、32％、35％或上述两两端点组成的范围中的任意点值。
根据本公开的实施方案，所述内核区域的孔隙率大于所述外壳区域的孔隙率。示例性地，所述内核区域的孔隙率为60％～90％，例如为60％、62％、65％、68％、70％、72％、75％、78％、80％、82％、85％、88％、90％或上述两两端点组成的范围中的任意点值。
本公开对孔隙率的测试方法不做具体限定，可采用本技术领域已知的方法测得。
根据本公开的实施方案，所述包覆材料的厚度为2nm～8nm。
根据本公开的实施方式，所述正极材料的比表面积为8m2/g～15m2/g，例如8m2/g、9m2/g、10m2/g、11m2/g、12m2/g、13m2/g、14m2/g、15m2/g或上述两两端点组成的范围中的任意点值。
根据本公开的实施方案，所述正极材料的电子电导率为2.0×10-2S/cm～9.0×10-2S/cm。
根据本公开的实施方案，所述正极材料的锂离子扩散系数为1.0×10-11cm2/s～9.0×10-11cm2/s。
根据本公开的实施方案，所述正极活性材料的质量占所述正极材料总质量的97.5wt％～99.0wt％，例如为97.5wt％、98wt％、98.5wt％、99wt％或上述两两端点组成的范围中的任意点值。
根据本公开的实施方案，所述包覆材料的质量占所述正极材料总质量的1wt％～2.5wt％，例如为1wt％、1.5wt％、2wt％、2.5wt％或上述两两端点组成的范围中的任意点值。
根据本公开的实施方案，所述正极活性材料的内核区域的中值粒径D50为1.2μm～2.6μm，例如1.2μm、1.3μm、1.4μm、1.5μm、1.6μm、1.7μm、1.8μm、1.9μm、2μm、2.1μm、2.2μm、2.3μm、2.4μm、2.5μm、2.6μm或上述两两端点组成的范围中的任意点值。
根据本公开的实施方案，所述内核区域和所述外壳区域的组成相同，均为磷酸铁锂LiFePO4。
根据本公开的实施方案，所述二次球形颗粒是指由磷酸铁锂一次颗粒堆积形成的球形的二次颗粒结构。
根据本公开的实施方案，所述内核区域是由小粒径(200nm-300nm)的磷酸铁锂一次颗粒团聚形成，所述的内核区域是孔隙率为60％～90％的团聚疏松结构。
根据本公开的实施方案，所述外壳区域是由大粒径(300nm-500nm)的磷酸铁锂一次颗粒团聚形成，所述的外壳区域是孔隙率为10％～35％的团聚密实结构。
根据本公开的实施方案，所述正极活性材料的化学式LiaFexMn1-x-y-zMyNzPO4中0<x≤0.6。
根据本公开的实施方案，所述正极活性材料的化学式为LiFexMn1-x-y-zMyNzPO4。
根据本公开的实施方案，0≤y+z≤0.04；具体的，0.0015≤y+z≤0.04，例如y+z为0.0015、0.002、0.003、0.004、0.005、0.006、0.007、0.008、0.009、0.01、0.02、0.03或0.04。
根据本公开的实施方案，所述M和N的摩尔比为(1～3):1，例如1:1、2:1、3:1或上述两两端点组成的范围中的任意点值。
根据本公开的实施方案，所述外壳区域具有孔隙。示例性地，所述外壳区域的孔隙率为大于0且小于等于30％，例如为0.1％、0.5％、1％、5％、10％、12％、15％、18％、20％、22％、25％、28％、30％或上述两两端点组成的范围中的任意点值。
根据本公开的实施方案，所述内核区域的孔隙率大于所述外壳区域的孔隙率。示例性地，所述内核区域的孔隙率为65％～90％，例如为65％、68％、70％、72％、75％、78％、80％、82％、85％、88％、90％或上述两两端点组成的范围中的任意点值。。
本公开对孔隙率的测试方法不做具体限定，可采用本技术领域已知的方法测得。
根据本公开的实施方案，所述二次球形颗粒的内核区域的中值粒径D50为1.0μm～2.8μm，例如1.0μm、1.1μm、1.2μm、1.3μm、1.4μm、1.5μm、1.6μm、1.7μm、1.8μm、1.9μm、2μm、2.1μm、2.2μm、2.3μm、2.4μm、2.5μm、2.6μm、2.7μm、2.8μm或上述两两端点组成的范围中的任意点值。
根据本公开的实施方案，所述正极材料中，所述包覆材料与所述正极活性材料的质量比(g/g)为(1.0～2.5):100，例如1:100、1.5:100、2:100、2.5:100或上述两两端点组成的范围中的任意点值。
根据本公开的实施方案，所述正极材料的比表面积为10m2/g～18m2/g，例如10m2/g、11m2/g、12m2/g、13m2/g、14m2/g、15m2/g、16m2/g、17m2/g、18m2/g或上述两两端点组成的范围中的任意点值。
根据本公开的实施方案，所述正极材料的放电克容量大于150mAh/g，优选为大于150mAh/g且小于200mAh/g。
本公开还提供一种正极片，所述正极片包括上述正极材料。
根据本公开的实施方案，所述正极片可根据本技术领域已知的方法制备得到，例如还可以包括导电剂、粘结剂或本领域已知的其他材料，本公开中不做具体限定。
根据本公开的实施方案，所述正极片包括正极集流体和位于所述正极集流体表面的正极活性层；所述正极活性层包括上述正极材料。
根据本公开的实施方案，所述正极活性层中各组分的质量百分含量为：70wt％～99wt％的所述正极材料、0.5wt％～15wt％的所述导电剂和0.5wt％～15wt％的所述粘结剂。
优选地，所述正极活性层中各组分的质量百分含量为：
96wt％～98wt％的所述正极材料、1wt％～2wt％的导电剂乙炔黑、1wt％～1.5wt％的导电剂碳纳米管、和0.5wt％～1.0wt％的粘结剂聚偏氟乙烯(PVDF)。
根据本公开的实施方案，所述正极活性层中各组分的质量百分含量为：
96wt％～97.5wt％的所述正极材料、1wt％～2wt％的导电剂乙炔黑、1wt％～1.5wt％的导电剂碳纳米管和0.5wt％～1.0wt％的粘结剂聚偏氟乙烯(PVDF)。
本公开还提供上述正极材料或上述正极片在电池中的应用。
本公开还提供一种电池，所述电池包括上述正极材料或上述正极片。
根据本公开的实施方案，所述电池为锂离子电池。
根据本公开的实施方案，所述电池可根据本技术领域已知的方法制备得到，例如还可以包括负极、隔膜和电解液等，所述负极、所述隔膜和所述电解液可根据本领域已知的方法进行选择，本公开中不做具体限定。
根据本公开的实施方案，所述电池的体积能量密度为225KWh/m3～255KWh/m3，重量能量密度为175Wh/kg～215Wh/kg。
根据本公开的实施方案，所述电池的倍率性能大于90％，优选为91％～99％。
根据本公开的实施方案，所述电池在25℃±2℃温度下充放电循环后的循环容量保持率在90％及以上，优选为90％～99％。
根据本公开的实施方案，所述电池的EIS阻抗值小于等于6mΩ，优选为0.1mΩ～6mΩ。
本公开中所述的倍率性能是指在25℃下，电池的10C放电容量与0.33C放电容量的比值。
本公开中所述的循环容量保持率是指在25℃或45℃下，电池在1C充电和1C放电条件下，循环n次后测试容量与首次循环测试容量的比值，其中n＝1500～5000。
本公开的有益效果：
(1)本公开的正极材料为具有核壳结构的微球，所述壳具有团聚密实结构；所述核具有团聚疏松结构(甚至其中心位置部分为中空的)，特殊的核壳结构能够缓解电池在充放电时由于颗粒膨胀和收缩所产生的应力负载，从而达到提升倍率性能和循环性能的目的；
(2)本公开的正极活性材料为具有核壳结构的微球，颗粒粒径大小可控，所述正极活性材料中的外壳具有团聚密实结构；所述正极活性材料中的内核具有团聚疏松结构(甚至其中心位置部分为中空的)，此结构有利于提升电解液的浸润效果，同时内部疏松结构使锂离子的扩散距离得到缩短，缩短了锂离子的扩散路径，其还为锂离子的扩散提供了多种路径，使得正极材料的锂离子的扩散能力和极化效应得到显著改善；
(3)本公开的正极材料在磷酸锰铁锂的基础上，通过双元素的掺杂，双元素之间形成有效的协同作用，使得磷酸锰铁锂的电子电导率和锂离子扩散速率得到显著提升，应用于电池具有良好的电化学性能。金属离子掺杂提升磷酸铁锂的电子电导率和离子扩散速率，双元素掺杂的协同作用可以提升磷酸铁锂正极材料的放电克容量和循环性能，与单一元素掺杂或无掺杂相比，能从多方面提升磷酸锰铁锂的电化学性能；
(4)本公开采用所述正极材料制备成正极片并应用在锂电池层面时具有优异的循环性能和高输出功率性能，应用于电池级别的安全性能较高；
(5)将本公开的正极材料制作为正极片并应用于电池时，电芯的首次充放电效率、库伦效率、低温性能、倍率性能和安全性能得到显著提升，解决了现有技术中磷酸锰锂的锂离子扩散速度低、极化现象等问题，材料的安全性能与倍率性能得到显著提升。
附图说明
图1是本公开的正极材料的结构示意图；
图2是实施例1的正极材料的XRD图；
图3是实施例1的正极材料的SEM剖面图；
图4是对比例1的正极材料的SEM剖面图；
图5是实施例5的磷酸锰铁锂正极材料的XRD图；
图6是实施例5的磷酸锰铁锂正极材料的SEM图；
图7是实施例5的磷酸锰铁锂正极材料的剖面SEM图；
图8是实施例5的磷酸锰铁锂正极材料的氮气吸脱附曲线；
图9是实施例9的正极材料的剖面SEM图；
图10是实施例9的掺杂型磷酸锰铁锂正极材料的XRD图谱；
图11是对比例2的磷酸锰铁锂正极材料的剖面SEM图；
图12是实施例1的充放电曲线(扣式电池)；
图13是对比例1的充放电曲线(扣式电池)；
图14是实施例5的充放电曲线(扣式电池)；
图15是对比例2的充放电曲线(扣式电池)；
图16是实施例9的充放电曲线；
图17是实施例5的倍率性能图(软包电芯)；
图18是实施例9的45℃循环容量保持率图；
图19是实施例1的软包电芯在25℃循环容量保持率；
图20是实施例1的软包电芯在45℃循环容量保持率；
图21是实施例9的阻抗图；
图22是本公开一实例中的正极活性材料的TEM谱图。
具体实施方式
本公开还提供上述正极材料的制备方法，以正极活性材料为磷酸锰锂为例，所述制备方法包括如下步骤：
A1)分别配置正极活性材料的前驱体溶液、络合剂溶液、pH调节溶液和反应液；
A2)将步骤A1)的正极活性材料的前驱体溶液、络合剂溶液以及pH调节溶液注入到反应液中进行第一次共沉淀反应，得到含有正极活性材料前驱体晶核的溶液；
A3)将步骤A1)的络合剂溶液以及pH调节溶液再次注入上述步骤A2)获得的含有正极活性材料前驱体晶核的溶液中，进行第二次共沉淀反应，直至反应得到目标粒径后终止反应，制备得到Mn3(PO4)2正极活性材料前驱体；
A4)将步骤A3)得到的Mn3(PO4)2正极活性材料前驱体均匀分散至Li3PO4晶体溶液中进行晶核生长，得到LiMnPO4前驱体；
A5)将步骤A4)得到的LiMnPO4前驱体与碳源进行混合，于惰性气氛下进行高温焙烧，制备得到所述正极材料。
根据本公开的实施方案，步骤A1)中，所述正极活性材料的前驱体溶液包括锰离子(Mn2+)和磷酸根离子(PO4 3-)。
根据本公开的实施方案，所述锰离子由锰盐提供。进一步优选地，所述锰盐选自(CH3COO)2Mn、MnSO4、MnC2O4或MnCl2中的至少一种。
根据本公开的实施方案，所述磷酸根离子由含磷酸根离子的可溶于水的化合物提供。进一步地，所述含磷酸根离子的可溶于水的化合物选自磷酸或其他可溶性磷酸盐，所述可溶性磷酸盐选自(NH4)H2PO4、(NH4)2HPO4或(NH4)3PO4中的至少一种。
根据本公开的实施方案，所述锰离子(Mn2+)和所述磷酸根离子(PO4 3-)的总摩尔浓度为1mol/L～3mol/L。
根据本公开的实施方案，所述磷酸根离子(PO4 3-)与所述锰离子(Mn2+)的摩尔比为(0.98～1.05):1。
根据本公开的实施方案，步骤A1)中，所述络合剂溶液中含有络合剂。
根据本公开的实施方案，所述络合剂选自草酸、柠檬酸或EDTA的至少一种。
根据本公开的实施方案，所述络合剂溶液的浓度为1mol/L～3mol/L。
根据本公开的实施方案，步骤A1)中，所述pH调节溶液中包含有机酸和/或无机酸。示例性地，所述有机酸选自乙酸或草酸。示例性地，所述无机酸选自碳酸。
根据本公开的实施方案，所述pH调节溶液的浓度为0.025mol/L～0.30mol/L。
根据本公开的实施方案，步骤A1)中，所述反应液为醇类溶剂和水组成的混合溶剂。
根据本公开的实施方案，所述醇类溶剂选自乙二醇、丙三醇、聚乙二醇400或聚乙二醇200中的至少一种。
根据本公开的实施方案，所述醇类溶剂和所述水的体积比为(1～5):1，优选为(2～3):1。
根据本公开的实施方案，步骤A2)为正极活性材料前驱体的成核及内核生长阶段。
根据本公开的实施方案，步骤A2)和步骤A3)中，通过调控所述络合剂溶液以及所述pH调节溶液的添加量控制步骤A2)和步骤A3)的反应条件。
根据本公开的实施方案，步骤A2)中，反应条件包括：pH值为1.5～2.4，所述络合剂浓度为0.02mol/L～0.05mol/L，在此条件下，可以制备得到具有团聚疏松结构的内核区域。
根据本公开的实施方案，步骤A2)中，所述第一次共沉淀反应的时间为8h～20h，所述第一次共沉淀反应的温度为50℃～75℃，所述第一次共沉淀反应过程中持续通入惰性气体，如氮气。
根据本公开的实施方案，步骤A3)为正极活性材料前驱体的外壳生产阶段。
根据本公开的实施方案，步骤A3)中，所述正极材料前驱体中的正极活性材料的分子式为Mn3(PO4)2。
根据本公开的实施方案，步骤A3)中，反应条件包括：pH值为2.6～3.5，所述络合剂浓度为0.1mol/L～0.3mol/L，在此条件下，可以制备得到具有团聚密实结构的外壳区域。
根据本公开的实施方案，步骤A3)中，所述第二次共沉淀反应的时间为48h～96h，所述第二次共沉淀反应的温度为50℃～75℃，所述第二次共沉淀反应过程中持续通入惰性气体，如氮气。
根据本公开的实施方案，所述第一次共沉淀反应和所述第二次共沉淀反应均在搅拌条件下进行，优选地，所述第一次共沉淀反应时的搅拌速率大于所述第二次共沉淀反应时的搅拌速率。示例性地，所述第一次共沉淀反应的搅拌速率为200rpm～650rpm，所述第二次共沉淀反应的搅拌速率为150rpm～500rpm。
根据本公开的实施方案，步骤A3)中，所述目标粒径是指D50控制在2μm～5μm。
根据本公开的实施方案，步骤A3)中，还包括通过对反应后的浆料进行固液分离、陈化、烘干、研磨、筛分和除杂质后得到Mn3(PO4)2正极活性材料前驱体。
根据本公开的实施方案，步骤A4)中，所述Li3PO4晶体溶液是通过如下方法制备得到的：
将磷酸溶液加入至LiOH溶液中进行反应，形成所述Li3PO4晶体溶液。
其中，所述磷酸溶液为磷酸水溶液，其摩尔浓度为1.0mol/L～2.5mol/L；所述LiOH溶液为LiOH水溶液，其摩尔浓度为1.0mol/L～2.5mol/L；体系中Li+与PO4 3-的摩尔比值为(0.96～1.10):1。
根据本公开的实施方案，步骤A4)中，Li3PO4与Mn3(PO4)2的添加量以体系中Li+与Mn2+的摩尔比值为 (0.96～1.10):1。
根据本公开的实施方案，步骤A5)中，所述碳源选自有机碳源和/或无机碳源。优选地，所述有机碳源选自葡萄糖、蔗糖、柠檬糖、聚苯胺或PEDOT导电聚合物中的至少一种。优选地，所述无机碳源选自碳纳米管、导电石墨烯或导电炭黑中的至少一种。
根据本公开的实施方案，步骤A5)中，所述混合例如为搅拌、球磨或研磨等中的至少一种。
根据本公开的实施方案，步骤A5)中，所述惰性气氛包括氮气或氩气等中的至少一种。
根据本公开的实施方案，步骤A5)中，所述碳源与所述LiMnPO4前驱体的质量比(g/g)为(0.07～0.12):1。
根据本公开的实施方案，步骤A5)中，所述焙烧包括多段控温烧结，具体包括如下步骤：以3℃/min升温速率由室温升至500℃～600℃，先在500℃～600℃下保温4h～6h，然后升温至650℃～800℃下保温8h～12h，得到所述正极材料。
根据本公开的实施方案，步骤A5)中，所述碳源在高温下裂解为无定型炭并均匀沉积在所述正极活性材料的表面。
本公开所提供的正极材料的制备方法的有益效果：本公开提供一种电池的制备方法，该电池包括正极片、负极片、商业化的电池隔膜和电解液，采用标准化作业的方式制备得到商业化电池，可在软包电芯或圆柱型电芯层面进行应用，具备较高的商业价值与实际意义。
本公开还提供上述正极材料的另一种制备方法，以正极活性材料为LiaFexMn1-x-y-zMyNzPO4，0<x≤0.6，0≤y≤0.02，0≤z≤0.02(其中M和N为共掺杂元素)为例，所述制备方法具体包括如下步骤：
B1)分别配置正极活性材料的前驱体三元溶液、络合剂溶液、pH调节溶液和任选加入或不加入的掺混溶液；配置反应液并搅拌；
B2)正极材料前驱体的成核及内核生长阶段：将步骤B1)的正极活性材料的前驱体三元溶液、络合剂溶液以及pH调节溶液注入到反应液中发生第一次共沉淀，得到含有正极活性材料前驱体晶核的溶液；
B3)正极材料前驱体的外壳生产阶段：将所述络合剂溶液以及所述pH调节溶液再次注入上述步骤B2)获得的含有正极活性材料前驱体晶核的溶液中，在搅拌下进行第二次共沉淀，直至反应得到目标粒径D50后终止反应，得到正极材料前驱体；
B4)将步骤B3)得到的正极材料前驱体、磷酸盐、锂盐和碳源进行球磨混合，于惰性气氛下进行高温焙烧，得到所述正极材料。
根据本公开的实施方案，步骤B1)中，所述正极活性材料的前驱体三元溶液包括亚铁离子(Fe2+)、锰离子(Mn2+)和磷酸根离子(PO4 3-)。
根据本公开的实施方案，所述亚铁离子由可溶性亚铁盐提供。进一步优选地，所述可溶性亚铁盐选自FeC2O4、FeSO4、FeCl2或(CH3COO)2Fe中的至少一种。
根据本公开的实施方案，所述锰离子由锰盐提供。进一步优选地，所述锰盐选自(CH3COO)2Mn、MnSO4、MnC2O4或MnCl2中的至少一种。
根据本公开的实施方案，所述磷酸根离子由含磷酸根离子的可溶于水的化合物提供。进一步地，所述含磷酸根离子的可溶于水的化合物选自磷酸或其他可溶性磷酸盐，所述可溶性磷酸盐选自(NH4)H2PO4、(NH4)2HPO4或(NH4)3PO4中的至少一种。
根据本公开的实施方案，所述亚铁离子和所述锰离子的总和(Fe2++Mn2+)与所述磷酸根离子(PO4 3-)的摩尔比为(2.85～3.15):2。
根据本公开的实施方案，所述亚铁离子(Fe2+)、所述锰离子(Mn2+)和所述磷酸根离子(PO4 3-)的总摩尔浓度为1mol/L～3mol/L。
根据本公开的实施方案，所述络合剂溶液中含有络合剂。
根据本公开的实施方案，所述络合剂选自草酸、柠檬酸或EDTA的至少一种。
根据本公开的实施方案，所述络合剂的浓度为1mol/L～3mol/L。
根据本公开的实施方案，所述pH调节溶液中包含有机酸和/或无机酸。示例性地，所述有机酸选自乙酸或草酸。示例性地，所述无机酸选自碳酸。
根据本公开的实施方案，所述pH调节溶液的浓度为0.05mol/L～0.25mol/L。
根据本公开的实施方案，所述掺混溶液中含有钒离子和铌离子。
优选地，所述钒离子由钒盐提供，例如所述钒盐选自钒的硫酸盐或氯化盐。
优选地，所述铌离子由铌盐提供，例如所述铌盐选自铌的硫酸盐或氯化盐。
优选地，所述掺混溶液中，所述钒离子和所述铌离子的摩尔比为(0.5～2):1。
优选地，所述掺混溶液的浓度为0.01mol/L～0.05mol/L。
根据本公开的实施方案，步骤B1)中，所述反应液为醇类溶剂和水组成的混合溶剂。
根据本公开的实施方案，所述醇类溶剂选自乙二醇、丙三醇、聚乙二醇400或聚乙二醇200中的至少 一种。
根据本公开的实施方案，所述醇类溶剂和水的体积比为(1～5):1，优选为(2～3):1。
根据本公开的实施方案，步骤B2)中，所述晶核的粒径D50为1.0μm～2.8μm。
根据本公开的实施方案，步骤B2)中，(Fe2++Mn2+):(V5++Nb5+)摩尔比为(99.1～99.9):(0.1～0.9)，例如为99.5:0.5或99.6:0.4。
根据本公开的实施方案，步骤B2)和步骤B3)中，反应温度为50℃～70℃，反应过程中持续通入惰性气体，如氮气。本公开中，通过调控所述络合剂溶液以及所述pH调节溶液的添加量控制步骤B2)和步骤B3)的反应条件。
根据本公开的实施方案，步骤B2)中，反应条件包括：pH值为1.5～2.4，所述络合剂浓度为0.02mol/L～0.05mol/L。
根据本公开的实施方案，步骤B2)中，所述第一次共沉淀反应时间为8h～20h。
根据本公开的实施方案，步骤B3)中，反应条件包括：pH值为2.6～3.5，所述络合剂浓度为0.1mol/L～0.25mol/L。
根据本公开的实施方案，步骤B3)中，所述第二次共沉淀反应时间为48h～96h。
根据本公开的实施方案，所述第一次共沉淀和所述第二次共沉淀均在搅拌条件下进行，优选地，所述第一次共沉淀时的搅拌速率大于所述第二次共沉淀时的搅拌速率。示例性地，所述第一次共沉淀的搅拌的速率为200rpm～650rpm，所述第二次共沉淀的搅拌速率为150rpm～500rpm。
根据本公开的实施方案，步骤B3)中，所述目标粒径是指粒径D50控制在3μm～7μm。
根据本公开的实施方案，步骤B3)中，所述正极活性前驱体通过对反应后的浆料进行固液分离、陈化、烘干、研磨、筛分和除杂质后得到。
根据本公开的实施方案，步骤B3)中，所述正极活性前驱体的内核区域由步骤B2)中所述的晶核形成的团聚疏松的微小粒子组成，表层的外壳区域由团聚密实的大粒子组成，所述内核区域及所述外壳区域的粒子组成成分一致。
根据本公开的实施方案，步骤B4)中，所述锂盐中锂离子(Li+)与所述亚铁离子、所述锰离子和任选的所述钒离子和所述铌离子的总和的摩尔比为(0.96～1.10):1。
根据本公开的实施方案，所述锂盐选自碳酸锂、氢氧化锂、草酸锂或乙酸锂中的至少一种。
根据本公开的实施方案，步骤B4)中，所述磷盐中的磷酸根离子(PO4 3-)与所述亚铁离子、所述锰离子和任选的所述钒离子和所述铌离子的总和的摩尔比为(0.95～1.10):1。优选地，所述磷盐选自上述含磷酸根离子的可溶于水的化合物中的至少一种。
根据本公开的实施方案，步骤B4)中，所述碳源选自有机碳源和/或无机碳源。优选地，所述有机碳选自于葡萄糖、蔗糖、柠檬糖、聚苯胺或PEDOT导电聚合物中的至少一种。
根据本公开的实施方案，步骤B4)中，所述碳源与所述正极材料前驱体质量比(g/g)为(0.07～0.10):1。
根据本公开的实施方案，步骤B4)中，所述焙烧包括多段控温烧结，具体包括如下步骤：以3℃/min升温速率由室温升至500℃～600℃，先在500℃～600℃下保温4h～6h，然后升温至650℃～800℃下保温8h～12h，得到所述正极材料，所述碳源在高温下裂解为不定形碳并均匀沉积在所述正极活性材料的表面。
本公开所提供的正极材料的制备方法的有益效果：
(1)本公开对常规的共沉淀法进行优化，制备得到内外一次颗粒结构不同的核壳结构前驱体，提供了一种制备特殊核壳结构的正极材料的新思路。本公开能够克服常规合成方法制备的磷酸锰铁锂正极材料高阻抗和循环性能较差的不足和缺陷问题，应用于电池层面具备较优的电化学性能；
(2)本公开在制备过程中无需添加造孔剂或模板剂，通过优化合成方法，制备得到一定粒径的、且进一步具有特殊核壳结构的正极材料，具有较高的放电克容量，成本低廉，产品纯度较高，工艺简单，可实现工业化级别生产。
下文将结合具体实施例对本公开做更进一步的详细说明。应当理解，下列实施例仅为示例性地说明和解释本公开，而不应被解释为对本公开保护范围的限制。凡基于本公开上述内容所实现的技术均涵盖在本公开旨在保护的范围内。
下述实施例中所使用的实验方法如无特殊说明，均为常规方法；下述实施例中所用的试剂、材料等，如无特殊说明，均可从商业途径得到。
实施例1-4及对比例1
实施例1
一、正极材料准备
(1).分别配置二元溶液、草酸溶液以及乙酸溶液待用，其中，二元溶液中包括MnSO4和H3PO4，二元溶液的摩尔浓度为1.5mol/L，其中体系中PO4 3-与Mn2+的摩尔比为1.02:1；配置反应液并搅拌，反应液为 丙三醇与水体积比为2:1的混合溶剂；草酸溶液浓度为1.25mol/L；乙酸溶液浓度为0.15mol/L；
(2).将二元溶液、草酸溶液以及乙酸溶液注入到反应液中得到混合溶液，进行阶段1和阶段2反应，反应温度调控为65℃，反应过程中持续通入氮气：
阶段1：将上述混合溶液注入到反应器中，搅拌转速控制在400rpm，草酸溶液浓度控制在0.03mol/L，溶液pH值调控在2.2，形成中间反应液，阶段1的共沉淀反应时间为12h，此过程为前驱体的成核及内核生长阶段，得到前驱体晶核；
阶段2：将草酸溶液以及乙酸溶液注入上述步骤获得的前驱体晶核溶液中，调节体系pH值至3.0，络合剂浓度调控在0.2mol/L，在350rpm搅拌速率下进行共沉淀反应，此阶段为前驱体的外壳生产阶段，直至目标粒径达到3.5μm后终止反应，得到Mn3(PO4)2前驱体；前驱体的内核区域由团聚疏松的微小粒子组成，外壳区域由团聚密实的大粒子组成，内核区域及外壳区域的粒子组成成分均为Mn3(PO4)2；
(3).将反应后的浆料进行固液分离、陈化、烘干、研磨、筛分和除杂质后得到Mn3(PO4)2前驱体；
(4).将磷酸溶液加入至LiOH溶液中进行反应，形成所述Li3PO4晶体溶液；所述磷酸溶液为磷酸水溶液，其摩尔浓度为1.25mol/L；所述LiOH溶液为LiOH水溶液，其摩尔浓度为1.5mol/L，体系中Li+与PO4 3-摩尔比值为1.02:1；将所述Mn3(PO4)2前驱体均匀分散至Li3PO4晶体溶液中进行晶核生长，晶核反应时间为8h，反应结束得到LiMnPO4前驱体，按照Li+与Mn2+摩尔比为1.04:1称取Li3PO4与Mn3(PO4)2；
(5).将葡萄糖与LiMnPO4前驱体按质量比为0.10:1的比例进行混合，于惰性气氛下进行高温焙烧，烧结过程中采用多段控温烧结的方式，以3℃/min升温速率由室温升至580℃，先在580℃下保温4h，然后升温至700℃下保温8h，样品自然冷却至室温后得到碳包覆结构的磷酸锰锂，记为LiMnPO4/C，其中，碳硫仪测得碳含量为2.2％(质量比)，比表面积(BET数值)见表1。
正极材料的粒径D50为3.8μm，经孔隙率测试仪测试可知，内核区域和外壳区域的孔隙率分别为75％和26％。
图2为实施例1的磷酸锰锂正极材料的XRD图，可以看出实施例1制备得到的为标准磷酸锰锂材料，PDF卡片匹配结果良好。
图3是实施例1的正极材料的SEM剖面图，可以看出实施例1的正极材料内核区域由团聚疏松的微小粒子组成，外壳区域由团聚密实的大粒子组成，内核区域为疏松结构，而且部分为中空结构。
二、扣式电池组装：将上述制备得到的正极材料、导电剂乙炔黑和粘结剂PVDF按质量比94:3:3称量均匀混合，并用N-甲基吡咯烷酮(NMP)溶剂进行分散形成浆液；浆料均匀涂覆在铝箔片并在80℃下干燥12h，干燥后的极片切成圆片放入手套箱中备用；采用上述所制备的极片作为正极片，金属锂作为负极，Celgard2400(微孔聚丙烯膜)作为隔膜，1mol/L的LiPF6(EC:DMC:DMC＝1:1:1)作为电解液，组装成2032型纽扣式电池，锂离子电池的组装须在用氩气作为保护气的手套箱内进行。
三、软包电芯制作：
(1)正极片制备
将上述制备得到的正极材料、粘结剂聚偏氟乙烯(PVDF)、导电剂乙炔黑和碳纳米管按照重量比96.5:1.5:1.5:0.5进行混合，加入N-甲基吡咯烷酮(NMP)，在真空搅拌机作用下搅拌，直至混合体系成均一流动性的正极浆料，正极浆料固含值为54％～58％，浆料粘度值控制在2500mPa.s～4500mPa.s；将正极浆料均匀涂覆于厚度为(10+2)μm的涂炭铝箔上，面密度控制在15mg/cm2～18mg/cm2；将上述涂覆好的铝箔在5段不同温度梯度的烘箱烘烤后，然后经过辊压、分切得到所需的正极片。
(2)负极片制备
将负极活性材料石墨、增稠剂羧甲基纤维素钠(CMC-Na)、粘结剂丁苯橡胶和导电剂乙炔黑按照重量比97:1.2:1.2:0.6进行混合，加入去离子水，在真空搅拌机作用下获得负极浆料；将负极浆料均匀涂覆在厚度为8μm的铜箔上；将上述涂覆好的铜箔在3段不同温度梯度的烘箱烘烤后，然后经过二次辊压、分切得到负极片。
(3)电解液制备
在充满氩气，水氧含量合格的手套箱中，将碳酸乙烯酯、碳酸丙烯酯和碳酸二乙酯按照质量比1:1:1的比例混合均匀(溶剂和添加剂需一起进行归一化)，然后往其中快速加入1mol/L的充分干燥的六氟磷酸锂(LiPF6)，搅拌均匀，经过水分和游离酸检测合格后，得到所需的电解液。
(4)隔离膜的制备
选用7μm+3μm混涂隔膜(基材聚丙烯膜+PVDF&陶瓷混合涂层)(旭化成公司提供)。
(5)锂离子电池的制备
将上述准备的正极片、隔离膜和负极片按顺序叠放好，两层隔膜包裹负极片，保证隔离膜处于正、负极片之间起到隔离的作用，然后通过卷绕得到未注液的裸电芯；将裸电芯置于外包装箔中，将上述制备好的电解液注入到干燥后的裸电芯中，经过真空封装、静置、化成、整形和分选等工序，获得软包电芯。
实施例2
一、正极材料准备
(1).分别配置二元溶液、EDTA溶液以及草酸溶液待用，其中，二元溶液中包括MnCl2和H3PO4，二元溶液的摩尔浓度为1.25mol/L，其中体系中PO4 3-与Mn2+的摩尔比为0.98:1；配置反应液并搅拌，反应液为乙二醇与水体积比为2:1的混合溶剂；EDTA溶液浓度为1.25mol/L；草酸溶液浓度为0.15mol/L；
(2).将二元溶液、EDTA溶液以及草酸溶液注入到反应液中得到混合溶液，进行阶段1和阶段2反应，反应温度调控为60℃，反应过程中持续通入氮气：
阶段1：将上述混合溶液注入到反应器中，搅拌转速控制在420rpm，EDTA溶液浓度控制在0.05mol/L，溶液pH值调控在2.0，形成中间反应液，阶段1的共沉淀反应时间为10h，此过程为前驱体的成核及内核生长阶段，得到前驱体晶核；
阶段2：将EDTA溶液以及草酸溶液注入上述步骤获得的前驱体晶核溶液中，调节体系pH值至3.0，络合剂浓度调控在0.25mol/L，在360rpm搅拌速率下进行共沉淀反应，此阶段为前驱体的外壳生产阶段，直至目标粒径达到3.0μm后终止反应，得到Mn3(PO4)2前驱体；前驱体的内核区域由团聚疏松的微小粒子组成，外壳区域由团聚密实的大粒子组成，内核区域及外壳区域的粒子组成成分均为Mn3(PO4)2；
(3).将反应后的浆料进行固液分离、陈化、烘干、研磨、筛分和除杂质后得到Mn3(PO4)2前驱体；
(4).将磷酸溶液加入至LiOH溶液中进行反应，形成所述Li3PO4晶体溶液；所述磷酸溶液为磷酸水溶液，其摩尔浓度为1.0mol/L；所述LiOH溶液为LiOH水溶液，其摩尔浓度为1.25mol/L，体系中Li+与PO4 3-摩尔比值为1.05:1；将所述Mn3(PO4)2前驱体均匀分散至Li3PO4晶体溶液中进行晶核生长，晶核反应时间为9h，反应结束得到LiMnPO4前驱体，按照Li+与Mn2+摩尔比为1.02:1称取Li3PO4与Mn3(PO4)2；
(5).将导电聚合物PEDOT与LiMnPO4前驱体按质量比为0.09:1的比例进行混合，于惰性气氛下进行高温焙烧，烧结过程中采用多段控温烧结的方式，以3℃/min升温速率由室温升至560℃，先在560℃下保温5h，然后升温至680℃下保温10h，样品自然冷却至室温后得到碳包覆结构的磷酸锰锂，记为LiMnPO4/C，其中，碳硫仪测得碳含量为1.8％(质量比)，比表面积(BET数值)见表1。
正极材料的粒径D50为3.2μm，经孔隙率测试仪测试可知，内核区域和外壳区域的孔隙率分别为80％和28％。
二、扣式电池组装：步骤同实施例1。
三、软包电芯制作：步骤同实施例1。
实施例3
一、正极材料制备
(1).分别配置二元溶液、柠檬酸溶液以及碳酸溶液待用，其中，二元溶液中包括MnC2O4和(NH4)H2PO4，二元溶液的摩尔浓度为1.5mol/L，其中体系中PO4 3-与Mn2+的摩尔比为1.05:1；配置反应液并搅拌，反应液为聚乙二醇200与水体积比为1:1的混合溶剂；柠檬酸溶液浓度为2.0mol/L；碳酸溶液浓度为0.1mol/L；
(2).将二元溶液、柠檬酸溶液以及碳酸溶液注入到反应液中得到混合溶液，进行阶段1和阶段2反应，反应温度调控为55℃，反应过程中持续通入氮气：
阶段1：将上述混合溶液注入到反应器中，搅拌转速控制在550rpm，柠檬酸溶液浓度控制在0.04mol/L，溶液pH值调控在1.6，形成中间反应液，阶段1的共沉淀反应时间为15h，此过程为前驱体的成核及内核生长阶段，得到前驱体晶核；
阶段2：将柠檬酸溶液以及碳酸溶液注入上述步骤获得的前驱体晶核溶液中，调节体系pH值至2.8，络合剂浓度调控在0.3mol/L，在420rpm搅拌速率下进行共沉淀反应，此阶段为前驱体的外壳生产阶段，直至目标粒径达到3.8μm后终止反应，得到Mn3(PO4)2前驱体；前驱体的内核区域由团聚疏松的微小粒子组成，外壳区域由团聚密实的大粒子组成，内核区域及外壳区域的粒子组成成分均为Mn3(PO4)2；
(3).将反应后的浆料进行固液分离、陈化、烘干、研磨、筛分和除杂质后得到Mn3(PO4)2前驱体；
(4).将磷酸溶液加入至LiOH溶液中进行反应，形成所述Li3PO4晶体溶液；所述磷酸溶液为磷酸水溶液，其摩尔浓度为1.5mol/L；所述LiOH溶液为LiOH水溶液，其摩尔浓度为1.75mol/L，体系中Li+与PO4 3-摩尔比值为0.98:1；将所述Mn3(PO4)2前驱体均匀分散至Li3PO4晶体溶液中进行晶核生长，晶核反应时间为6h，反应结束得到LiMnPO4前驱体，按照Li+与Mn2+摩尔比为1.04:1称取Li3PO4与Mn3(PO4)2；
(5).将蔗糖与LiMnPO4前驱体按质量比为0.08:1的比例进行混合，于惰性气氛下进行高温焙烧，烧结过程中采用多段控温烧结的方式，以3℃/min升温速率由室温升至600℃，先在600℃下保温5h，然后升温至750℃下保温10h，样品自然冷却至室温后得到碳包覆结构的磷酸锰锂，记为LiMnPO4/C，其中，碳硫仪测得碳含量为1.6％(质量比)，比表面积(BET数值)见表1。
正极材料的粒径D50为4.0μm，经孔隙率测试仪测试可知，内核区域和外壳区域的孔隙率分别为82％和31％。
二、扣式电池组装：步骤同实施例1。
三、软包电芯制作：步骤同实施例1。
实施例4
(1).分别配置二元溶液、EDTA溶液以及乙酸溶液待用，其中，二元溶液中包括(CH3COO)2Mn和(NH4)2HPO4，二元溶液的摩尔浓度为2.5mol/L，其中体系中PO4 3-与Mn2+的摩尔比为1:1，配置反应液并搅拌，反应液为聚乙二醇400与水体积比为1:1的混合溶剂；EDTA溶液为1.8mol/L；乙酸溶液浓度为0.2mol/L；
(2).将二元溶液、EDTA溶液以及乙酸溶液注入到反应液中得到混合溶液，进行阶段1和阶段2反应，反应温度调控为65℃，反应过程中持续通入氮气：
阶段1：将上述混合溶液注入到反应器中，搅拌转速控制在500rpm，EDTA溶液浓度控制在0.04mol/L，溶液pH值调控在2.0，形成中间反应液，阶段1的共沉淀反应时间为10h，此过程为前驱体的成核及内核生长阶段，得到前驱体晶核；
阶段2：将EDTA溶液以及乙酸溶液注入上述步骤获得的前驱体晶核溶液中，调节体系pH值至3.0，络合剂浓度调控在0.25mol/L，在450rpm搅拌速率下进行共沉淀反应，此阶段为前驱体的外壳生产阶段，直至目标粒径达到3.2μm后终止反应，得到Mn3(PO4)2前驱体；前驱体的内核区域由团聚疏松的微小粒子组成，外壳区域由团聚密实的大粒子组成，内核区域及外壳区域的粒子组成成分均为Mn3(PO4)2；
(3).将反应后的浆料进行固液分离、陈化、烘干、研磨、筛分和除杂质后得到Mn3(PO4)2前驱体；
(4).将磷酸溶液加入至LiOH溶液中进行反应，形成所述Li3PO4晶体溶液；所述磷酸溶液为磷酸水溶液，其摩尔浓度为1.25mol/L；所述LiOH溶液为LiOH水溶液，其摩尔浓度为2.0mol/L，体系中Li+与PO4 3-摩尔比值为1:1；将所述Mn3(PO4)2前驱体均匀分散至Li3PO4晶体溶液中进行晶核生长，晶核反应时间为8h，反应结束得到LiMnPO4前驱体，按照Li+与Mn2+摩尔比为1.02:1称取Li3PO4与Mn3(PO4)2；
(5).将葡萄糖与LiMnPO4前驱体按质量比为0.12:1的比例进行混合，于惰性气氛下进行高温焙烧，烧结过程中采用多段控温烧结的方式，以3℃/min升温速率由室温升至580℃，先在580℃下保温6h，然后升温至720℃下保温10h，样品自然冷却至室温后得到碳包覆结构的磷酸锰锂，记为LiMnPO4/C，其中，碳硫仪测得碳含量为2.0％(质量比)，比表面积(BET数值)见表1。
正极材料的粒径D50为3.4μm，经孔隙率测试仪测试可知，内核区域和外壳区域的孔隙率分别为76％和25％。
二、扣式电池组装：步骤同实施例1。
三、软包电芯制作：步骤同实施例1。
对比例1
一、正极材料制备
(1).分别配置二元溶液、柠檬酸溶液以及草酸溶液待用，其中，二元溶液中包括MnC2O4和H3PO4，二元溶液的摩尔浓度为1.2mol/L，其中体系中PO4 3-与Mn2+的摩尔比为1.02:1；配置反应液并搅拌，反应液为乙二醇和水体积比为3:1的混合溶剂；其中柠檬酸溶液浓度为2.0mol/L，草酸溶液浓度为0.15mol/L；
(2).将二元溶液、柠檬酸溶液以及草酸溶液注入到反应液中得到混合溶液，进行共沉淀反应；反应温度调控为70℃，反应过程中持续通入氮气：
将上述混合溶液注入到反应器中，通过微调草酸溶液添加量调节体系pH值至2.2，络合剂浓度调控在0.12mol/L，在450rpm搅拌速率下进行共沉淀反应，直至目标粒径达到4.5μm后终止反应，得到Mn3(PO4)2前驱体；
(3).将反应后的浆料进行固液分离、陈化、烘干、研磨、筛分和除杂质后得到Mn3(PO4)2前驱体；
(4).将磷酸溶液加入至LiOH溶液中进行反应，形成所述Li3PO4晶体溶液；所述磷酸溶液为磷酸水溶液，其摩尔浓度为1.0mol/L；所述LiOH溶液为LiOH水溶液，其摩尔浓度为1.5mol/L，体系中Li+与PO4 3-摩尔比值为1.02:1；将所述Mn3(PO4)2前驱体均匀分散至Li3PO4晶体溶液中进行晶核生长，晶核反应时间为10h，反应结束得到LiMnPO4前驱体，按照Li+与Mn2+摩尔比为1.05:1称取Li3PO4与Mn3(PO4)2；
(5).将葡萄糖与LiMnPO4前驱体按质量比为0.1:1的比例进行混合，于惰性气氛下进行高温焙烧，烧结过程中采用多段控温烧结的方式，以3℃/min升温速率由室温升至550℃，先在550℃下保温4h，然后升温至660℃下保温10h，样品自然冷却至室温后得到碳包覆结构的磷酸锰锂，记为LiMnPO4/C，其中，碳硫仪测得碳含量为1.8％(质量比)，比表面积(BET数值)见表1。
正极材料的粒径D50为4.6μm，经孔隙率测试仪测试可知，正极活性材料LiMnPO4的孔隙率为28％。
图4是对比例1的正极材料的SEM剖面图，可以看出对比例1制备得到的正极材料为由一次颗粒紧密堆积形成的二次球形结构，为实心球形颗粒，不存在中空状或者团聚疏松结构，相较于实施例1制备得到的团聚疏松结构，对比例1的正极材料具备较低的孔隙率。图4中表面的小颗粒为电镜拍摄过程中抽真空导致。
二、扣式电池组装：步骤同实施例1。
三、软包电芯制作：步骤同实施例1。
实施例5-12及对比例2
实施例5
一、正极材料制备：
(1).分别配置三元溶液、草酸溶液以及乙酸溶液待用；其中，三元溶液中包括FeSO4、MnSO4和H3PO4，三元溶液的总摩尔浓度为1.5mol/L，Fe2+与Mn2+摩尔比为2:8，(Fe2++Mn2+)总和与PO4 3-的摩尔比为3:2；配置反应液并搅拌，反应液为乙二醇和水体积比为3:1的混合溶剂；草酸溶液浓度为2mol/L；乙酸溶液浓度为0.15mol/L；
(2).将三元溶液、草酸溶液及乙酸溶液注入到反应液中得到混合溶液，进行阶段1和阶段2反应，其中，反应温度调控为55℃，反应过程中持续通入氮气：
阶段1：将上述混合溶液注入到反应器中，搅拌转速控制在400rpm，形成中间反应液，其中，草酸溶液浓度控制在0.025mol/L，溶液pH值调控在1.8，阶段1的共沉淀反应时间为12h，此过程为前驱体的成核及内核生长阶段，得到含有前驱体晶核的溶液，所述晶核的粒径D50为2.6μm；
阶段2：将上述草酸溶液和乙酸溶液注入上述阶段1获得的含有前驱体晶核的溶液中，调节体系pH值至2.6，络合剂浓度调控在0.15mol/L，在300rpm搅拌速率下进行共沉淀反应，此阶段为前驱体的外壳生产阶段，直至目标粒径D50达到5.5μm后终止反应，得到(Fe0.2Mn0.8)3(PO4)2前驱体；前驱体的内核区域由上述晶核形成的团聚疏松的微小粒子组成，外壳区域由团聚密实的大粒子组成，内核区域及外壳区域的粒子组成成分均为(Fe0.2Mn0.8)3(PO4)2；
(3).将步骤(2)反应后的浆料进行固液分离、陈化、烘干、研磨、筛分和除杂质后得到(Fe0.2Mn0.8)3(PO4)2前驱体；
(4).将步骤(3)的(Fe0.2Mn0.8)3(PO4)2前驱体、(NH4)H2PO4、LiOH和葡萄糖进行球磨混合，其中，(NH4)H2PO4和所述亚铁离子和锰离子的总和(Fe2++Mn2+)的摩尔比为1.02:1；LiOH和所述亚铁离子和锰离子的总和(Fe2++Mn2+)的摩尔比为1.05:1；葡萄糖与前驱体的质量比为0.08:1的比例进行混合，于惰性气氛下进行高温焙烧，烧结过程中采用多段控温烧结的方式，先以3℃/min升温速率由室温升至550℃，在550℃下保温6h，然后升温至680℃下保温10h，自然冷却至室温后得到碳包覆结构的磷酸锰铁锂正极材料，记为LiFe0.2Mn0.8PO4/C，其中，采用碳硫仪测得碳含量为1.5％(质量比)，比表面积(BET数值)见表1。经孔隙率测试仪测试可知，内核区域和外壳区域的孔隙率分别为78％和22％。
图5是实施例5的磷酸锰铁锂正极材料的XRD图，可以看出制备得到的为固溶体材料，PDF卡片匹配结果为磷酸锰铁锂。
图6是实施例5的磷酸锰铁锂正极材料的SEM图；从图中可以看出制备得到的为球形颗粒，颗粒尺寸大小为4μm～5μm。
图7是实施例5的正极材料的颗粒剖面SEM图，可以看出，正极材料内核区域由团聚疏松粒子组成，外壳区域由团聚密实粒子组成，内核区域为疏松结构，而且部分为中空结构。
图8是实施例5的磷酸锰铁锂正极材料的氮气吸脱附曲线；从图中可以看出曲线具有明显的滞留环，制备得到的材料具有介孔结构。
二、扣式电池组装：将上述正极材料、导电剂乙炔黑和粘结剂PVDF按质量比90:5:5称量均匀混合，并用N-甲基吡咯烷酮(NMP)溶剂进行分散形成浆液；浆料均匀涂覆在铝箔片并在80℃下干燥12h得到正极极片，干燥后的正极极片经辊压后切成圆片放入手套箱中备用。采用上述所制备的圆片作为正极，金属锂作为负极，Celgard 2400(微孔聚丙烯膜)作为隔膜，1mol/L的LiPF6(EC:EMC:DMC＝1:1:1)作为电解液，组装成2032型纽扣式电池，锂离子电池的组装须在用氩气作为保护气的手套箱内进行。
三、软包电芯制作：将上述制备得到的正极材料作为正极，人工石墨作为负极，商业化的电解液，隔膜，在锂离子电池生产线组装为软包电芯，其中，正极极片包括：正极材料、导电剂(导电炭黑+碳纳米管，质量比为1.5:0.5)和粘结剂PVDF按质量比为96.5:2:1.5进行均匀混合，溶剂采用N-甲基吡咯烷酮NMP，搅拌均匀制得浆料后涂布至铝箔集流体，正极集流体为(10+2)μm涂炭铝箔；极片经高温烘烤后进行辊压制片，并裁切成正极片备用。负极极片包括：人工石墨、导电剂乙炔黑、羧甲基纤维素钠CMC和粘结剂LA133按质量比为96.5:1:1:1.5进行均匀混合，溶剂采用去离子水，搅拌均匀制得浆料后涂布至铜箔集流体，负极集流体为6μm铜箔；并裁切成负极片备用。电解液基准为1mol/L的LiPF6(EC:EMC:DMC＝1:1:1)+添加剂(双氟磺酰亚胺锂)；隔膜为7μm+3μm混涂隔膜(基材+PVDF&陶瓷混合涂层)。
实施例6
一、正极材料制备：
(1).分别配置三元溶液、柠檬酸溶液以及碳酸溶液待用，其中，三元溶液中包括FeC2O4、MnC2O4和(NH4)H2PO4，三元溶液的总摩尔浓度为1.25mol/L，Fe2+与Mn2+摩尔比为3:7，(Fe2++Mn2+)总和与PO4 3-的摩尔比为3.15:2；配置反应液并搅拌，反应液为聚乙二醇400与水体积比为2:1的混合溶剂；柠檬酸溶液浓度为1.5mol/L；碳酸溶液浓度为0.1mol/L；
(2).将三元溶液、柠檬酸溶液以及碳酸溶液注入到反应液中得到混合溶液，进行阶段1和阶段2反应，反应温度调控为60℃，反应过程中持续通入氮气：
阶段1：将上述混合溶液注入到反应器中，搅拌转速控制在500rpm，柠檬酸溶液浓度控制在0.03mol/L，溶液pH值调控在1.7，形成中间反应液，阶段1的共沉淀反应时间为10h，此过程为前驱体的成核及内核生长阶段，得到含有前驱体晶核溶液，所述晶核的粒径D50为2.5μm；
阶段2：将柠檬酸溶液以及碳酸溶液注入上述阶段1获得的前驱体晶核溶液中，调节体系pH值至2.6，络合剂浓度调控在0.2mol/L，在400rpm搅拌速率下进行共沉淀反应，此阶段为前驱体的外壳生产阶段，直至目标粒径D50达到4.8μm后终止反应，得到(Fe0.3Mn0.7)3(PO4)2前驱体；前驱体的内核区域由团聚疏松的微小粒子组成，外壳区域由团聚密实的大粒子组成，内核区域及外壳区域的粒子组成成分均为(Fe0.3Mn0.7)3(PO4)2；
(3).将反应后的浆料进行固液分离、陈化、烘干、研磨、筛分和除杂质后得到(Fe0.3Mn0.7)3(PO4)2前驱体；
(4).将上述制备得到的(Fe0.3Mn0.7)3(PO4)2前驱体、(NH4)H2PO4、Li2CO3和蔗糖进行球磨混合，其中，(NH4)2HPO4和所述亚铁离子和锰离子的总和(Fe2++Mn2+)的摩尔比为1.05:1，Li2CO3和所述亚铁离子和锰离子的总和(Fe2++Mn2+)的摩尔比为0.98:1；蔗糖与前驱体按质量比为0.07:1的比例进行混合，于惰性气氛下进行高温焙烧，烧结过程中采用多段控温烧结的方式，3℃/min升温速率由室温升至580℃，先在580℃下保温5h，然后升温至700℃下保温8h，自然冷却至室温后得到碳包覆结构的LiFe0.3Mn0.7PO4/C，其中，碳硫仪测得碳含量为1.6％(质量比)，比表面积(BET数值)见表1。经孔隙率测试仪测试可知，内核区域孔隙率为80％，外壳区域孔隙率为25％。
二、扣式电池组装：步骤同实施例5。
三、软包电芯制作：步骤同实施例5。
实施例7
一、正极材料制备：
(1).分别配置三元溶液、柠檬酸溶液以及乙酸溶液待用，其中，三元溶液中包括(CH3COO)2Fe、(CH3COO)2Mn和(NH4)2HPO4，三元溶液的总摩尔浓度为1.75mol/L，Fe2+与Mn2+摩尔比为4:6，(Fe2++Mn2+)总和与PO4 3-的摩尔比为3.06:2；配置反应液并搅拌，反应液为乙二醇与水体积比为2:1的混合溶剂；柠檬酸溶液浓度为1.75mol/L；乙酸溶液浓度为0.25mol/L；
(2).将三元溶液、柠檬酸溶液以及乙酸溶液注入到反应液中得到混合溶液，进行阶段1和阶段2反应，反应温度调控为65℃，反应过程中持续通入氮气：
阶段1：将上述混合溶液注入到反应器中，搅拌转速控制在450rpm，柠檬酸溶液浓度控制在0.035mol/L，溶液pH值调控在2.0，形成中间反应液，阶段1的共沉淀反应时间为10h，此过程为前驱体的成核及内核生长阶段，得到含有前驱体晶核的溶液，所述晶核的粒径D50为2.6μm；
阶段2：将柠檬酸溶液以及乙酸溶液注入上述步骤获得的前驱体晶核溶液中，调节体系pH值至2.8，络合剂浓度调控在0.15mol/L，在400rpm搅拌速率下进行共沉淀反应，此阶段为前驱体的外壳生产阶段，直至目标粒径D50达到5.8μm后终止反应，得到(Fe0.4Mn0.6)3(PO4)2前驱体；前驱体的内核区域由团聚疏松的微小粒子组成，外壳区域由团聚密实的大粒子组成，内核区域及外壳区域的粒子组成成分均为(Fe0.4Mn0.6)3(PO4)2；
(3).将反应后的浆料进行固液分离、陈化、烘干、研磨、筛分和除杂质后得到(Fe0.4Mn0.6)3(PO4)2前驱体；
(4).将上述制备得到的(Fe0.4Mn0.6)3(PO4)2前驱体、(NH4)H2PO4、CH3COOLi和导电聚合物聚苯胺进行球磨混合，其中，(NH4)H2PO4与(Fe0.4Mn0.6)3(PO4)2的摩尔比为1.04:0.33，CH3COOLi与(Fe0.4Mn0.6)3(PO4)2的摩尔比为1.02:0.33；导电聚合物聚苯胺与前驱体按质量比为0.10:1的比例进行混合，于惰性气氛下进行高温焙烧，烧结过程中采用多段控温烧结的方式，以3℃/min升温速率由室温升至550℃，先在550℃下保温4h，然后升温至720℃下保温8h，样品自然冷却至室温后得到碳包覆结构的LiFe0.4Mn0.6PO4/C，其中，碳硫仪测得碳含量为2.1％(质量比)，比表面积(BET数值)见表1。经孔隙率测试仪测试可知，内核区域孔隙率为82％，外壳区域孔隙率为24％。
二、扣式电池组装：步骤同实施例5。
三、软包电芯制作：步骤同实施例5。
实施例8
一、正极材料制备：
(1).分别配置三元溶液、柠檬酸溶液以及碳酸溶液待用，其中，三元溶液中包括FeCl2、MnSO4和H3PO4，三元溶液的总摩尔浓度为1.25mol/L，Fe2+与Mn2+摩尔比为2:8，(Fe2++Mn2+)总和与PO4 3-的摩尔比为3.1:2；配置反应液并搅拌，反应液为聚乙二醇200和水体积比为2:1的混合溶剂；柠檬酸溶液浓度为2.25mol/L；碳酸溶液浓度为0.2mol/L；
(2).将三元溶液、柠檬酸溶液以及碳酸溶液注入到反应液中得到混合溶液，进行阶段1和阶段2反应，反应温度调控为60℃，反应过程中持续通入氮气：
阶段1：将上述混合溶液注入到反应器中，搅拌转速控制在450rpm，柠檬酸溶液浓度控制在0.025mol/L，溶液pH值调控在2.2，形成中间反应液，阶段1的共沉淀反应时间为15h，此过程为前驱体的成核及内核生长阶段，得到含有前驱体晶核的溶液，所述晶核的粒径D50为2.75μm；
阶段2：将柠檬酸溶液以及碳酸溶液注入上述步骤获得的前驱体晶核溶液中，调节体系pH值至2.8，络合剂浓度调控在0.2mol/L，在400rpm搅拌速率下进行共沉淀反应，此阶段为前驱体的外壳生产阶段，直至目标粒径D50达到6.0μm后终止反应，得到(Fe0.2Mn0.8)3(PO4)2前驱体；前驱体的内核区域由团聚疏松的微小粒子组成，外壳区域由团聚密实的大粒子组成，内核区域及外壳区域的粒子组成成分均为(Fe0.2Mn0.8)3(PO4)2；
(3).将反应后的浆料进行固液分离、陈化、烘干、研磨、筛分和除杂质后得到(Fe0.2Mn0.8)3(PO4)2前驱体；
(4).将上述制备得到的(Fe0.2Mn0.8)3(PO4)2前驱体、(NH4)H2PO4、Li2CO3和导电聚合物PEDOT进行球磨混合，其中，(NH4)H2PO4与所述亚铁离子和锰离子的总和(Fe2++Mn2+)的摩尔比为1:1；Li2CO3与所述亚铁离子和锰离子的总和(Fe2++Mn2+)的摩尔比为1.02:1；导电聚合物PEDOT与前驱体质量比为0.09:1的比例进行混合，于惰性气氛下进行高温焙烧，烧结过程中采用多段控温烧结的方式，以3℃/min升温速率由室温升至580℃，先在580℃下保温4h，然后升温至680℃下保温10h，样品自然冷却至室温后得到碳包覆结构的正极材料，记为LiFe0.2Mn0.8PO4/C其中，碳硫仪测得碳含量为1.8％(质量比)，比表面积(BET数值)见表1。经孔隙率测试仪测试可知，内核区域孔隙率为85％，外壳区域孔隙率为26％。
二、扣式电池组装：步骤同实施例5。
三、软包电芯制作：步骤同实施例5。
实施例9
一、正极材料制备：
(1).分别配置三元溶液、混掺溶液、草酸溶液以及碳酸溶液待用；其中三元溶液包括FeSO4、MnSO4和H3PO4，三元溶液的总摩尔浓度为1.25mol/L，Fe2+与Mn2+摩尔比为2.5:7.5，(Fe2++Mn2+)总和与PO4 3-的摩尔比为3.06:2；混掺溶液包括VCl5和NbCl5，V5+与Nb5+摩尔比为1:2；配置反应液并搅拌，反应液为乙二醇和水体积比为2:1的混合溶剂；草酸溶液浓度为1.5mol/L，碳酸溶液浓度为0.125mol/L；
(2).将三元溶液、混掺溶液、草酸溶液及碳酸溶液注入到反应液中得到混合溶液，其中(Fe2++Mn2+):(V5++Nb5+)摩尔比为99.5:0.5，进行如下阶段1和阶段2反应，其中，反应温度调控为60℃，反应过程中持续通入氮气：
阶段1：将上述混合溶液注入到反应器中，搅拌转速控制在450rpm，草酸溶液浓度控制在0.025mol/L，溶液pH值调控在1.6，形成中间反应液，阶段1的共沉淀反应时间为15h，此过程为前驱体的成核及内核生长阶段，得到含有前驱体晶核的溶液，所述晶核的粒径D50为2.5μm；
阶段2：将草酸溶液以及碳酸溶液注入上述步骤获得的含有前驱体晶核的溶液中，调节体系pH值至2.8，络合剂浓度调控在0.15mol/L，在400rpm搅拌速率下进行共沉淀反应，此阶段为前驱体的外壳生产阶段，直至目标粒径D50达到4.0μm后终止反应，得到掺杂型前驱体；前驱体的内核区域由团聚疏松的微小粒子组成，外壳区域由团聚密实的大粒子组成，内核区域及外壳区域的粒子组成成分一致；
(3).将步骤(2)反应后的浆料进行固液分离、陈化、烘干、研磨、筛分和除杂质后得到共掺杂前驱体；
(4).将步骤(3)制备得到的共掺杂前驱体、(NH4)H2PO4、Li2CO3和蔗糖进行球磨混合，其中，(NH4)H2PO4中的PO4 3-和步骤(2)的混合溶液中亚铁离子、锰离子、钒离子和铌离子的总和的摩尔比为1.02:1，Li2CO3中的Li+和步骤(2)的混合溶液中亚铁离子、锰离子、钒离子和铌离子的总和的摩尔比为1.05:1；蔗糖和共掺杂前驱体按照质量比为0.08:1的比例进行混合，于惰性气氛下进行高温焙烧，烧结过程中采用多段控温烧结的方式，先以3℃/min升温速率由室温升至575℃，在575℃下保温6h，然后升温至680℃下保温8h，样品自然冷却至室温后得到碳包覆结构的掺杂型磷酸锰铁锂，其中，掺杂型磷酸锰铁锂的化学式为LiMn1-x-y-zFexMyNzPO4，其中M和N为共掺杂元素，掺杂元素M和N分别为Nb和V，x＝0.25，y＝0.0033，z＝0.0017，采用碳硫仪测得碳含量为1.8％(质量比)，比表面积(BET数值)见表1。经孔隙率测试仪测试可知，内核区域的孔隙率为85％，外壳区域的孔隙率为20％。
图9为实施例9的正极材料的颗粒剖面的SEM图，从图9中可以看出，正极材料内核区域由团聚疏松的微小粒子组成，外壳区域由团聚密实的大粒子组成，内核区域为疏松结构，而且部分为中空结构。
图10是实施例9采用共掺杂方法制备的磷酸锰铁锂正极材料的XRD图；从图10可知，随着掺杂元素的加入，衍射峰的位置与相对强度未发生显著变化，表明实施例9的正极材料中的掺杂元素成功嵌入晶格结构中，且形成的是一个纯的固溶体，制备的正极材料为橄榄石结构磷酸锰铁锂，同时掺杂量变化也并未破坏材料的晶体结构。
二、扣式电池组装：步骤同实施例5。
三、软包电芯制作：步骤同实施例5。
实施例10
一、正极材料制备：
(1).配置FeC2O4、MnC2O4和(NH4)H2PO4溶液、混掺溶液VCl5和NbCl5、柠檬酸溶液以及乙酸溶液待用，其中FeC2O4、MnC2O4和(NH4)H2PO4摩尔浓度为1.5mol/L，Fe2+与Mn2+摩尔比为3:7，(Fe2++Mn2+)总和与PO4 3-的摩尔比为3:2，混掺溶液中V5+与Nb5+摩尔比为1:1。其中(Fe2++Mn2+):(V5++Nb5+)摩尔比为99.4:0.6，配置反应液并搅拌，反应液为聚乙二醇200和水体积比为2:1的混合溶剂；柠檬酸溶液浓度为1.75mol/L，乙酸溶液浓度为0.1mol/L；
(2).将FeC2O4、MnC2O4和(NH4)H2PO4溶液、混掺溶液VCl5和NbCl5、柠檬酸溶液及乙酸溶液注入到反应液中得到混合溶液，进行阶段1和阶段2反应，反应温度调控为65℃，反应过程中持续通入氮气：
阶段1：将上述混合溶液注入到反应器中，搅拌转速控制在500rpm，柠檬酸溶液浓度控制在0.025mol/L，溶液pH值调控在1.8，形成中间反应液，阶段1的共沉淀反应时间为12h，此过程为前驱体的成核及内核生长阶段，得到含有前驱体晶核的溶液，所述晶核的粒径D50为2.2μm；
阶段2：将柠檬酸溶液以及乙酸溶液注入上述步骤获得的前驱体晶核溶液中，调节体系pH值至3.0，络合剂浓度调控在0.175mol/L，在400rpm搅拌速率下进行共沉淀反应，此阶段为前驱体的外壳生产阶段，直至目标粒径D50达到4.5μm后终止反应，得到掺杂型前驱体；前驱体的内核区域由团聚疏松的微小粒子组成，外壳区域由团聚密实的大粒子组成，内核区域及外壳区域的粒子组成成分一致。
(3).将反应后的浆料进行固液分离、陈化、烘干、研磨、筛分和除杂质后得到共掺杂前驱体；
(4).将上述制备得到的共掺杂前驱体、(NH4)H2PO4、LiOH和蔗糖进行球磨混合，其中，(NH4)2HPO4和亚铁离子、锰离子、钒离子和铌离子的总和的摩尔比为1.02:1，Li2CO3中的Li+和亚铁离子、锰离子、钒离子和铌离子的总和的摩尔比为1.0:1，共掺杂前驱体与蔗糖按照质量比为1:0.09的比例进行混合，于惰性气氛下进行高温焙烧，烧结过程中采用多段控温烧结的方式，先以3℃/min升温速率由室温升至560℃，在560℃下保温4h，然后升温至700℃下保温8h，样品自然冷却至室温后得到碳包覆结构的掺杂型磷酸锰铁锂，其中，掺杂型磷酸锰铁锂的化学式为LiMn1-x-y-zFexMyNzPO4，其中，M和N为共掺杂元素，掺杂元素M、N分别为Nb和V，x＝0.298，y＝0.003，z＝0.003，碳硫仪测得碳含量为2％(质量比)，比表面积(BET数值)见表1。经孔隙率测试仪测试可知，内核区域的孔隙率为82％，外壳区域的孔隙率为18％。
二、扣式电池组装：步骤同实施例5。
三、软包电芯制作：步骤同实施例5。
实施例11
一、正极材料制备：
(1).配置(CH3COO)2Fe、(CH3COO)2Mn和(NH4)2HPO4溶液、混掺溶液VCl5和NbCl5、草酸溶液以及乙酸溶液待用，其中(CH3COO)2Fe、(CH3COO)2Mn和(NH4)2HPO4摩尔浓度为2.5mol/L，Fe2+与Mn2+摩尔比为2:8，(Fe2++Mn2+)总和与PO4 3-的摩尔比为3:2，混掺溶液中V5+与Nb5+摩尔比为2:1。其中(Fe2++Mn2+):(V5++Nb5+)摩尔比为99.4:0.6，配置反应液并搅拌，反应液为丙三醇和水体积比为2:1的混合溶剂；草酸溶液浓度为1.5mol/L，乙酸溶液浓度为0.15mol/L；
(2).将(CH3COO)2Fe、(CH3COO)2Mn和(NH4)2HPO4溶液、混掺溶液VCl5和NbCl5、草酸溶液及乙酸溶液注入到反应液中得到混合溶液，进行阶段1和阶段2反应，反应温度调控为55℃，反应过程中持续通入氮气：
阶段1：将上述混合溶液注入到反应器中，搅拌转速控制在400rpm，草酸溶液浓度控制在0.03mol/L，溶液pH值调控在2.0，形成中间反应液，阶段1的共沉淀反应时间为12h，此过程为前驱体的成核及内核生长阶段，得到含有前驱体晶核的溶液，所述晶核的粒径D50为2.4μm；
阶段2：将草酸溶液以及乙酸溶液注入上述步骤获得的前驱体晶核溶液中，调节体系pH值至3.2，络合剂浓度调控在0.2mol/L，在350rpm搅拌速率下进行共沉淀反应，此阶段为前驱体的外壳生产阶段，直至目标粒径D50达到3.5μm后终止反应，得到掺杂型前驱体；前驱体的内核区域由团聚疏松的微小粒子组成，外壳区域由团聚密实的大粒子组成，内核区域及外壳区域的粒子组成成分一致。
(3).将反应后的浆料进行固液分离、陈化、烘干、研磨、筛分和除杂质后得到共掺杂前驱体；
(4).将上述制备得到的共掺杂前驱体、(NH4)2HPO4、CH3COOLi和柠檬糖进行球磨混合，其中， (NH4)H2PO4与亚铁离子、锰离子、钒离子和铌离子的总和的摩尔比为1.04:1，CH3COOLi中的Li+与亚铁离子、锰离子、钒离子和铌离子的总和的摩尔比为1.02:1；共掺杂前驱体与柠檬糖按照质量比为1:0.1的比例进行混合，于惰性气氛下进行高温焙烧，烧结过程中采用多段控温烧结的方式，先以3℃/min升温速率由室温升至580℃，在580℃下保温6h，然后升温至720℃下保温12h，样品自然冷却至室温后得到碳包覆结构的掺杂型磷酸锰铁锂，其中，掺杂型磷酸锰铁锂的化学式为LiMn1-x-y-zFexMyNzPO4，其中，M和N为共掺杂元素，掺杂元素M、N分别为Nb和V，x＝0.198，y＝0.002，z＝0.004，碳硫仪测得碳含量为2.2％(质量比)，比表面积(BET数值)见表1。经孔隙率测试仪测试可知，内核区域的孔隙率为86％，外壳区域的孔隙率为22％。
二、扣式电池组装：步骤同实施例5。
三、软包电芯制作：步骤同实施例5。
实施例12
一、正极材料制备：
(1).配置FeCl2、MnCl2和H3PO4溶液、混掺溶液VCl5和NbCl5、柠檬酸溶液以及乙酸溶液待用，其中FeCl2、MnCl2和H3PO4摩尔浓度为1.25mol/L，Fe2+与Mn2+摩尔比为3.5:6.5，(Fe2++Mn2+)总和与PO4 3-的摩尔比为3.15:2，混掺溶液中V5+与Nb5+摩尔比为1:1；其中(Fe2++Mn2+):(V5++Nb5+)摩尔比为99.6:0.4，配置反应液并搅拌，反应液为乙二醇和水体积比为2:1的混合溶剂；柠檬酸溶液浓度为1.75mol/L，乙酸溶液浓度为0.2mol/L；
(2).将FeCl2、MnCl2和H3PO4溶液、混掺溶液VCl5和NbCl5、柠檬酸溶液及乙酸溶液注入到反应液中得到混合溶液，进行阶段1和阶段2反应，反应温度调控为60℃，反应过程中持续通入氮气：
反应阶段1：将上述混合溶液注入到反应器中，搅拌转速控制在450rpm，柠檬酸溶液浓度控制在0.025mol/L，溶液pH值调控在1.8，形成中间反应液，阶段1的共沉淀反应时间为12h，此过程为前驱体的成核及内核生长阶段，得到含有前驱体晶核的溶液，所述晶核的粒径D50为2.6μm；
反应阶段2：将柠檬酸溶液以及乙酸溶液注入上述步骤获得的前驱体晶核溶液中，调节体系pH值至2.8，络合剂浓度调控在0.2mol/L，在400rpm搅拌速率下进行共沉淀反应，此阶段为前驱体的外壳生产阶段，直至目标粒径D50达到4.0μm后终止反应，得到掺杂型前驱体；前驱体的内核区域由团聚疏松的微小粒子组成，外壳区域由团聚密实的大粒子组成，内核区域及外壳区域的粒子组成成分一致。
(3).将反应后的浆料进行固液分离、陈化、烘干、研磨、筛分和除杂质后得到共掺杂前驱体；
(4).将上述制备得到的共掺杂前驱体、(NH4)2HPO4、Li2CO3和葡萄糖进行球磨混合，其中，(NH4)H2PO4与亚铁离子、锰离子、钒离子和铌离子的总和的摩尔比为1.02:1；Li2CO3中的Li+与亚铁离子、锰离子、钒离子和铌离子的总和的摩尔比为0.98:1；共掺杂前驱体与葡萄糖按照质量比为1:0.08的比例进行混合，于惰性气氛下进行高温焙烧，烧结过程中采用多段控温烧结的方式，先以3℃/min升温速率由室温升至560℃，在560℃下保温5h，然后升温至700℃下保温10h，样品自然冷却至室温后得到碳包覆结构的掺杂型磷酸锰铁锂，其中，掺杂型磷酸锰铁锂的化学式为LiMn1-x-y-zFexMyNzPO4，其中，M和N为共掺杂元素，掺杂元素M和N分别为Nb和V，x＝0.3486，y＝0.003，z＝0.001，碳硫仪测得碳含量为1.8％(质量比)，比表面积(BET数值)见表1。经孔隙率测试仪测试可知，内核区域的孔隙率为82％，外壳区域的孔隙率为18％。
二、扣式电池组装：步骤同实施例5。
三、软包电芯制作：步骤同实施例5。
对比例2
一、正极材料制备：
(1).分别配置三元溶液、草酸溶液以及碳酸溶液待用，其中，三元溶液中包括(CH3COO)2Fe、MnC2O4和H3PO4，三元溶液的总摩尔浓度为1.5mol/L，Fe2+与Mn2+摩尔比为3:7，(Fe2++Mn2+)总和与PO4 3-的摩尔比为3.15:2；配置反应液并搅拌，反应液为聚乙二醇200和水体积比为2:1的混合溶剂；草酸溶液浓度为2.0mol/L，碳酸溶液浓度为0.15mol/L；
(2).将三元溶液、草酸溶液以及碳酸溶液注入到反应液中得到混合溶液，进行共沉淀反应，反应温度调控为60℃，反应过程中持续通入氮气；
将上述混合溶液注入到反应器中，通过微调碳酸溶液添加量调节体系pH值至2.6，络合剂浓度调控在0.15mol/L，在400rpm搅拌速率下进行共沉淀反应，直至目标粒径D50达到6.0μm后终止反应，得到(Fe0.3Mn0.7)3(PO4)2前驱体；
(3).将反应后的浆料进行固液分离、陈化、烘干、研磨、筛分和除杂质后得到(Fe0.3Mn0.7)3(PO4)2前驱体；
(4).将上述制备得到的(Fe0.3Mn0.7)3(PO4)2前驱体、(NH4)2HPO4、LiOH和葡萄糖进行球磨混合，其中(Fe0.3Mn0.7)3(PO4)2、(NH4)2HPO4和LiOH按摩尔比分别为0.33:1.05:1.02；葡萄糖与前驱体的质量比为0.08:1的比例进行混合，于惰性气氛下进行高温焙烧，烧结过程中采用多段控温烧结的方式，以3℃/min升温速 率由室温升至560℃，先在580℃下保温5h，然后升温至700℃下保温8h，样品自然冷却至室温后得到碳包覆结构的LiFe0.3Mn0.7PO4/C，其中，碳硫仪测得碳含量为1.6％(质量比)，比表面积(BET数值)见表1。
图11是对比例2的磷酸锰铁锂正极材料的SEM剖面图。从图中可以看出对比例2制备得到的为实心球形颗粒。而如图7所示的实施例5的正极材料的颗粒剖面SEM图可以看出，实施例5的正极材料内核区域由团聚疏松的粒子组成，外壳区域由团聚密实的粒子组成，内核区域的含有中空结构。
二、扣式电池组装：步骤同实施例5。
三、软包电芯制作：步骤同实施例5。
实施例13
一、正极材料制备：
(1).配置FeSO4和H3PO4溶液、混掺溶液VCl5和NbCl5、柠檬酸溶液以及乙酸溶液待用，其中FeSO4和H3PO4摩尔浓度为1.25mol/L，Fe2+与PO4 3-的摩尔比为3:2，混掺溶液中V5+与Nb5+摩尔比为1:1；其中Fe2+：(V5++Nb5+)摩尔比为99.6:0.4，配置反应液并搅拌，反应液为乙二醇和水体积比为2:1的混合溶剂；柠檬酸溶液浓度为1.75mol/L，乙酸溶液浓度为0.2mol/L；
(2).将FeSO4和H3PO4溶液、混掺溶液VCl5和NbCl5、柠檬酸溶液及乙酸溶液注入到反应液中得到混合溶液，进行阶段1和阶段2反应，反应温度调控为60℃，反应过程中持续通入氮气：
反应阶段1：将上述混合溶液注入到反应器中，搅拌转速控制在450rpm，柠檬酸溶液浓度控制在0.025mol/L，溶液pH值调控在1.8，形成中间反应液，阶段1的共沉淀反应时间为12h，此过程为前驱体的成核及内核生长阶段，得到含有前驱体晶核的溶液，所述晶核的粒径D50为2.6μm；
反应阶段2：将柠檬酸溶液以及乙酸溶液注入上述步骤获得的前驱体晶核溶液中，调节体系pH值至2.8，络合剂浓度调控在0.2mol/L，在400rpm搅拌速率下进行共沉淀反应，此阶段为前驱体的外壳生产阶段，直至目标粒径D50达到4.0μm后终止反应，得到掺杂型前驱体；前驱体的内核区域由团聚疏松的微小粒子组成，外壳区域由团聚密实的大粒子组成，内核区域及外壳区域的粒子组成成分一致；
(3).将反应后的浆料进行固液分离、陈化、烘干、研磨、筛分和除杂质后得到共掺杂前驱体；
(4).将上述制备得到的共掺杂前驱体、(NH4)2HPO4、Li2CO3和葡萄糖进行球磨混合，其中，(NH4)H2PO4与亚铁离子、钒离子和铌离子的总和的摩尔比为1.02:1；Li2CO3中的Li+与亚铁离子、钒离子和铌离子的总和的摩尔比为0.98:1；共掺杂前驱体与葡萄糖按照质量比为1:0.08的比例进行混合，于惰性气氛下进行高温焙烧，烧结过程中采用多段控温烧结的方式，先以3℃/min升温速率由室温升至560℃，在560℃下保温5h，然后升温至700℃下保温10h，样品自然冷却至室温后得到碳包覆结构的掺杂型磷酸锰铁锂，其中，掺杂型磷酸铁锂的化学式为LiFexMyNzPO4，其中，M和N为共掺杂元素，掺杂元素M和N分别为Nb和V，x＝0.996，y＝0.003，z＝0.001，碳硫仪测得碳含量为1.8％(质量比)，比表面积(BET数值)见表1。经孔隙率测试仪测试可知，内核区域的孔隙率为75％，外壳区域的孔隙率为28％。
二、扣式电池组装：步骤同实施例1。
三、软包电芯制作：步骤同实施例1。
测试例
1、充放电测试
实施例1-12和对比例1-2的扣式电池在25±5℃温度下进行充电性能测试，测试过程如下：
1)扣式电池活化24h；
2)0.1C恒流充电至上限电压4.5V后恒压充电，截止电流0.025C；
3)休息10分钟；
4)0.1C恒流放电至2.5V。
实施例13参照上述测试过程进行，所不同的是，步骤2)中的上限电压由4.5V改为3.65V。
如图12所示是实施例1的扣式电池充放电曲线；图13是对比例1的扣式电池的充放电曲线；如图14是实施例5的扣式电池充放电曲线；图15是对比例2的扣式电池的充放电曲线；图16是实施例9的充放电曲线。经计算，得到正极材料的放电克容量，结果见表1。
2、倍率测试
实施例1-12和对比例1-2的软包电池在25±2℃温度下进行倍率性能测试，测试过程如下：
1)25±2℃环境中0.33C/0.33C循环三次进行容量测试；
2)1C放电至下限电压(2.5V)；
3)静置30min；
4)1C恒流充电至上限电压(4.5V)后恒压充电，截止电流0.05C；
5)静置30min；
6)nC放电至下限电压2.5V，其中nC＝0.2C/0.33C/0.5C/1C/2C/3C/5C/8C/10C/15C；
7)重复步骤3～6完成所有倍率的放电步骤。
实施例13参照上述测试过程进行，所不同的是，步骤4)中的上限电压由4.5V改为3.65V。
经计算，得到各电池的倍率性能(倍率＝nC放电容量/0.33C容量)，图17是实施例5的软包电芯倍率性能图。倍率性能结果见表1。
3、循环容量测试
取实施例1-12和对比例1-2的软包电池，分别在25±2℃和45±2℃温度下进行循环容量测试，测试过程包括：
25℃±2℃(45℃±2℃)测试软包电池状态电压、内阻、厚度、直流内阻，电压范围(2.5V～4.5V)；
1)电芯置于25℃±2℃(45℃±2℃)环境下；
2)0.5C放电至下限电压，静置30min；
3)1C充电到上限电压，截止0.05C；
4)静置30min；
5)1C放电至下限电压；静置30min；
6)1C充电到上限电压，截止0.05C，静置30min；
重复5～6步循环至n圈。
实施例13参照上述测试过程进行，所不同的是，电压范围由2.5V～4.5V改为2.5V～3.65V。
图19是实施例1的软包电芯在25℃循环容量保持率；图20是实施例1的软包电芯在45℃循环容量保持率；图18是实施例9的45℃循环容量保持率图。在1C/1C、循环n圈(n≤5000)后，计算得到各电池的循环容量保持率，其中，首次循环测试容量记作A1，循环n次后测试容量记作An，容量保持率＝An/A1×100％，结果见表2。
4、热分解温度测试——DSC测试
对实施例1-12和对比例1-2的软包电芯以0.33C倍率满充至4.5V，并在充满氩气的手套箱中拆解回收正极片(不含正极集流体)，并用碳酸二甲酯(DMC)冲洗上述正极片并干燥。将上述正极片与电解液共同放置于热分析仪器的高压坩埚内，1mol/L的LiPF6(EC:EMC:DMC＝1:1:1)作为电解液，其中正极片与电解液添加按照1mg:0.6μL进行配制，热分析测试温度范围为25℃～500℃，升温速率为5℃/min。实施例13参照上述测试过程进行，所不同的是，以0.33C倍率满充至3.65V，测试结果见表1。
5、EIS阻抗值测试—交流阻抗法测试
电化学交流阻抗(EIS)测量在上海辰华CHI600E电化学工作站上进行，对实施例1-12和对比例1-2的软包电芯进行测试，并调节电池状态为50％SOC状态；电压窗口设定为2.5V～4.5V，幅度为5mV，频率范围为10-2～105Hz。实施例13参照上述测试过程进行，所不同的是，电压窗口由2.5V～4.5V改为2.5V～3.65V。图21是实施例9的阻抗图。测试结果见表1。
6、低温性能测试
对实施例1-4和对比例1的软包电池在25℃±2℃温度下测试软包电池状态电压、内阻和厚度；电压范围(2.5V～4.5V)；
1)25±2℃静置30min；
2)0.5C放电至下限电压；
3)静置4小时；
4)1C充电到上限电压，截止电流0.05C；
5)静置4小时；
6)恒温箱环境，在不同的温度(温度如下)下静置4小时后以1C放电至下限电压；
7)25±2℃静置4小时；
重复步骤4～7步，循环直到所有温度放电测试完成；
放电温度：25℃/45℃/0℃/-10℃/-20℃。
测试结果见表2。
7、正极材料电子电导率测试
将实施例1-4和对比例1制备得到的正极材料样品粉末混合5％的PVDF，用压片机压制成圆柱状薄片(Φ10.0mm)，利用四探针直流技术测试LiMnPO4/C样品的电子电导率。测试结果见表3。
8、正极材料的锂离子扩散系数测试
将实施例1-4和对比例1制备得到的正极材料，采用恒电流间歇滴定法(GITT方法)测试锂离子的扩散系数(DLi +)。
1)扣式电池活化24h；
2)0.1C恒流充电至上限电压(4.5V)后恒压充电，截止电流0.05C；
3)静置10分钟；
4)0.1C恒流放电15min；
5)静置30min；
6)重复步骤4-5步，直至放电工序完成。
实施例13参照上述测试过程进行，所不同的是，步骤2)中的上限电压由4.5V改为3.65V。
金属Li负极对于电池电压变化的影响较小，测试过程中的电压变化主要来自于正极材料，采用该方法得到的扩散系数主要反应正极材料的扩散系数。
利用上面得到的数据进行计算正极材料的扩散系数，重点关注4个电压数据，脉冲放电之前电压V0；恒流放电瞬间电压V1(脉冲瞬时放电)，V0与V1差值主要对应电池内部的欧姆阻抗和电荷转移阻抗等对电压变化的影响；恒流放电结束时电压V2，对应于Li+扩散进入到正极材料内部引起的电压变化；静置后期电压V3，对应于Li+在活性物质内部进行扩散，最终实现稳态出现的活性物质电压变化。根据上述数据同时结合菲克第二定律，采用下面所示公式进行计算Li+在锂离子电池内的扩散系数Ds。
Ds＝(4/πt)(Rs/3)2(△Vs/△Vt)2，
此处Rs为球形颗粒半径，t为放电脉冲持续时间，△Vs＝V0-V3；△Vt＝V1-V2。测试结果见表3。
表1实施例1-13和对比例1-2的电池性能
表2实施例1-13和对比例1-2的电池性能

注“-”表示未测试。
表3实施例1-4和对比例1的电池性能

注“-”表示未测试。
采用本公开的制备方法制备得到的实施例1～13正极材料为内核团聚疏松、外壳团聚密实结构(如图3、图7和图9所示)。
通过表1～3中的测试结果可知，实施例1～4的正极材料具有较小粒径的颗粒和特殊核壳结构使得材料具备较优的锂离子扩散能力和电子电导率，材料动力学性能较优；采用上述正极材料制备成正极片并应用于锂电池层面时，具备较优的动力学性能和倍率放电能力，同时低温放电性能和安全性能也得到显著提升。
通过表1和表2中的测试结果可知，实施例5～12的方案具有较大的二次颗粒粒径、比表面值和较高的放电克容量。将实施例5-8的正极材料制备成正极片并应用于锂离子电池时，电池的电化学性能优于对比例2。
实施例1～13制备的正极材料均为内核团聚疏松、外壳团聚密实结构，所述内核区域的中心位置具有团聚疏松结构，进一步地，所述内核区域的中心位置为中空的。示例性的，所述正极材料具有图1所示的示意结构。
核壳结构的微球有利于提升电解液的浸润效果和材料的电子电导率，同时内部疏松结构使锂离子的扩散距离得到缩短，材料的倍率性能和长循环性能得到显著提升。
采用实施例5～12的正极材料制备得到正极片并应用于锂离子电池时具有较为优异的长循环性能、低内阻和高输出功率，因此，本公开的正极材料适用于对安全性能要求较高的电池。
从表1和表2的结果可知，实施例9～12的正极材料通过钒和铌双元素的掺杂，形成有效的协同作用，磷酸锰铁锂的电子电导率和锂离子扩散速率也得到显著提升，材料的放电克容量增加。将实施例9～12的正极材料作为电池的正极，电池的倍率性能较优。同时，共掺杂还可以提升正极材料的耐高温性能，因此采用本公开的正极材料作为正极的电池，常温和高温循环稳定性能明显提高，而且具有高安全性能和低内阻、高输出功率，因此，本公开的正极材料适用于对安全性能要求较高的电池。
以上，对本公开的实施方式进行了说明。但是，本公开不限定于上述实施方式。凡在本公开的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本公开的保护范围之内。

Claims (15)

  1. 一种正极材料，其特征在于，所述正极材料包括正极活性材料和在所述正极活性材料表面的包覆材料；
    所述正极材料的中值粒径D50为2μm～7μm；
    所述正极活性材料的化学式为LiaFexMn1-x-y-zMyNzPO4，其中M和N为共掺杂元素，0.9≤a≤1.1，0≤x≤1，0≤y≤0.02，0≤z≤0.02。
  2. 根据权利要求1所述的正极材料，其特征在于，所述M选自铌、镁、钴、锌、镍或铜中的至少一种；
    和/或，所述N选自铝、钛、钒或铈中的至少一种；
    和/或，所述正极活性材料具有橄榄石型结构。
  3. 根据权利要求1或2所述的正极材料，其特征在于，所述正极活性材料为二次球形颗粒，所述二次球形颗粒包括内核区域和外壳区域，所述外壳区域位于所述内核区域的外层；所述外壳区域具有团聚密实结构；和/或，所述内核区域具有团聚疏松结构；和/或，所述正极材料的比表面积为8m2/g～25m2/g。
  4. 根据权利要求1-3任一项所述的正极材料，其特征在于，所述包覆材料包括碳材料；
    优选地，所述包覆材料包括不定形碳；
    优选地，所述包覆材料的厚度为2nm～10nm。
  5. 根据权利要求1-4任一项所述的正极材料，其特征在于，所述正极活性材料为LiaMn1-y-zMyNzPO4；
    优选地，所述LiaMn1-y-zMyNzPO4的电子电导率为1.0×10-5S/cm～9.0×10-5S/cm；
    优选地，所述LiaMn1-y-zMyNzPO4的锂离子扩散系数为1.0×10-14cm2/s～8.0×10-14cm2/s。
  6. 根据权利要求5所述的正极材料，其特征在于，所述外壳区域和/或所述内核区域具有孔隙；
    优选地，所述外壳区域的孔隙率为10％～35％；
    优选地，所述内核区域的孔隙率为60％～90％。
  7. 根据权利要求5或6所述的正极材料，其特征在于，所述正极活性材料的质量占所述正极材料总质量的97.5wt％～99.0wt％，所述包覆材料的质量占所述正极材料总质量的1wt％～2.5wt％。
  8. 根据权利要求2-7任一项所述的正极材料，其特征在于，所述正极活性材料的内核区域的中值粒径D50为1.2μm～2.6μm；
    优选地，所述正极活性材料为LiMnPO4；
    和/或，所述正极活性材料的内核区域由粒径为200nm-300nm的LiMnPO4一次颗粒团聚形成；
    和/或，所述正极活性材料的外壳区域由粒径为300nm-500nm的LiMnPO4一次颗粒团聚形成。
  9. 根据权利要求1-4任一项所述的正极材料，其特征在于，所述正极活性材料为LiaFexMyNzPO4；
    优选地，所述LiaFexMyNzPO4的电子电导率为2.0×10-2S/cm～9.0×10-2S/cm；
    优选地，所述LiaFexMyNzPO4的锂离子扩散系数为1.0×10-11cm2/s～9.0×10-11cm2/s。
  10. 根据权利要求1-4任一项所述的正极材料，其特征在于，所述正极活性材料的化学式LiaFexMn1-x-y-zMyNzPO4中0<x≤0.6；
    优选地，0.0015≤y+z≤0.04；
    优选地，所述M和所述N的摩尔比为(1～3):1。
  11. 根据权利要求10所述的正极材料，其特征在于，所述外壳区域和/或所述内核区域具有孔隙；
    优选地，所述外壳区域的孔隙率大于0且小于等于30％；
    优选地，所述内核区域的孔隙率为65％～90％。
  12. 根据权利要求10或11所述的正极材料，其特征在于，所述正极材料中，所述包覆材料与所述正极活性材料的质量比为(1.0～2.5):100；
    优选地，所述正极材料的比表面积为10m2/g～18m2/g；
    优选地，所述正极材料的放电克容量大于150mAh/g。
  13. 一种正极片，其特征在于，所述正极片包括权利要求1-12任一项所述的正极材料。
  14. 一种电池，其特征在于，所述电池包括权利要求1-12任一项所述的正极材料或权利要求13所述的正极片。
  15. 根据权利要求14所述的电池，其特征在于，所述电池的倍率性能为大于90％；
    和/或，所述电池在1500次充放电循环后的循环容量保持率在90％以上；
    和/或，所述电池的EIS阻抗值小于等于6mΩ。
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