CN113072049B - Preparation method of high-compaction-density lithium manganese iron phosphate/carbon composite positive electrode material - Google Patents
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Abstract
The invention disclosesA preparation method of a high-compaction-density lithium manganese iron phosphate/carbon composite positive electrode material has a chemical general formula as follows: liMn x Fe y PO 4 X is more than or equal to 0.5 and less than or equal to 0.9, and x + y =1; the preparation method comprises the following steps: diluting phosphoric acid for later use, adding a manganese source, an iron source, a dispersing agent and deionized water into a sealable container, and introducing protective gas; adding diluted phosphoric acid into a sealed container, aging to ensure that the pH value is between 2.0 and 5.0, and uniformly nucleating; cleaning the formed precipitate, vacuum drying, and sintering at high temperature for the first time to form spherical particles A; preparing a solution by using lithium hydroxide monohydrate, adding the spherical particles A into the solution, performing spray drying, and performing high-temperature secondary sintering to obtain spherical particles B; and preparing a glucose solution, adding the spherical particles B into the glucose solution, spray-drying, and sintering at a high temperature for the third time to obtain the nano spherical lithium manganese phosphate/carbon composite material. The invention greatly improves the electrochemical performance and the material compaction density of the material.
Description
Technical Field
The invention belongs to the technical field of energy storage materials, and particularly relates to a preparation method of a high-compaction-density lithium manganese iron phosphate/carbon composite anode material.
Background
The use of Lithium Ion Batteries (LIBs) in hybrid and electric vehicles has generated considerable academic and industrial research interest. Polyanionic phosphate materials of olivine structure (LiMPO) since the original work of the Goodenough group 1997 4 M = Fe, mn, co, and Ni) has been widely studied as a positive electrode material due to its high theoretical capacity, thermal stability, and environmental friendliness. Based on safety requirements, liFePO 4 (LFP) has been successfully used in LIBs as an alternative to LiMnPO 4 (LMP) provides the same theoretical specific capacity (170 mAh g) -1 ) And with Fe 2+ /Fe 3+ In contrast, mn 2+ /Mn 3+ Is higher, thus making the theoretical energy density of LMP about 20% higher than that of LFP. Despite these advantages of LMP, it is still difficult to obtain LMP with significantly improved power density, high specific capacity and long-term cycling stability. Extremely low lithium ion diffusion coefficient (D) Li ，10 -16 ～10 -14 cm 2 S) and electron conductivity (<10 -10 s cm -1 ) Also reducing its electrochemical activity. In addition, LMP has a larger volume change during charge and discharge, and an unstable crystal structure during charge and discharge cycles results in a lower capacity retention rate. The Jahn-Teller effect, the dissolution of divalent Mn, leads to poor electrochemical performance of LMP. Ex situ carbon coating method only improves the secondary particle sizeConductive properties, and the in-situ carbon coating may be with LiMnPO 4 The anode material primary particles form a three-dimensional continuous conductive system, and the electronic conductivity among the primary particles is improved. In micron-scale battery materials, the kinetics of charge storage are generally determined by Li in the microparticles + The diffusion rate of (c). Therefore, the reaction kinetics can be improved by nanocrystallizing the LMP material. The Fe doping can mitigate lattice distortion caused by the Jahn-Teller effect, thereby stabilizing the crystal structure and enhancing charge transfer. Therefore, replacing Mn with an appropriate amount of Fe is to increase LiMnPO 4 A method for synthesizing lithium manganese iron phosphate (LiMn) with excellent electrochemical performance x Fe 1-x PO 4 ) The positive electrode material is necessary.
In addition, the synthesis method and preparation process determine the LiMn x Fe 1-x PO 4 The intrinsic structural characteristics of the particle size, the particle size distribution, the morphology, the specific surface area, the crystallinity, the lattice defects and the like directly influence the lithium ion deintercalation process, namely determine the electrochemical properties of the material, such as charge-discharge capacity, cycle life and the like. The traditional synthesis method, namely the solid phase method, has the advantages of simple synthesis process, uniform particles of materials and large inter-particle space. The hydrothermal method has obvious advantages in controlling chemical composition and crystallite size, but the synthetic material is lamellar and cannot realize densification.
For example, chinese patent publication No. CN104009234a discloses a method for synthesizing LiMn, a positive electrode material of a lithium ion battery, by using a coprecipitation-microwave method 0.7 Fe 0.3 PO 4 By reacting Li with a catalyst of 2 CO 3 、Fe 2 O 3 After phosphoric acid is metered according to a certain molar ratio, preparing phosphoric acid into a phosphoric acid solution, and adding citric acid into the phosphoric acid solution to prepare an aqueous solution of citric acid and phosphoric acid; mixing Li 2 CO 3 、Fe 2 O 3 Adding, and stirring to obtain paste mixture; aging and performing microwave heat treatment to obtain a precursor A; in the same way with Li 2 CO 3 、MnCO 3 Or MnO 2 Phosphoric acid as raw material to obtain precursor B, mixing the precursors A and B, adding glucose solution to obtain pasteA precursor; finally, the positive electrode material is obtained through microwave sintering, and the discharge capacity of the prepared lithium iron manganese phosphate positive electrode material is 138.6mAh g -1 。
Chinese patent publication No. CN103515599A discloses a preparation method of a lithium manganese phosphate and carbon nanotube nanocomposite, which comprises the steps of dripping phosphoric acid into a lithium hydroxide solution to prepare lithium phosphate; adding manganese salt and ferric salt into the lithium phosphate dispersion liquid, stirring to obtain a precursor solution, then sintering at high temperature to obtain lithium manganese phosphate or iron-doped lithium manganese phosphate, then performing catalyst deposition on the surface of the lithium manganese phosphate or iron-doped lithium manganese phosphate, and finally sintering in the atmosphere of carbon source gas and protective gas to obtain the lithium manganese phosphate and carbon nano tube nanocomposite or iron-doped lithium manganese phosphate and carbon nano tube nanocomposite.
Chinese patent publication No. CN109524644A discloses LiMn 1-x Mg x PO 4 The preparation method of the/C positive electrode material comprises the following steps: (1) Slowly dropping phosphoric acid or phosphate solution B into lithium salt solution A under the inert gas atmosphere and continuously stirring to obtain suspension C; (2) Slowly pouring the manganese salt and magnesium salt mixed solution D into the suspension C, uniformly stirring and dispersing, performing microwave reaction, cooling, centrifuging, washing, vacuum drying and grinding to obtain manganese magnesium lithium phosphate precursor powder; (3) Ball-milling and uniformly mixing the manganese, magnesium and lithium phosphate precursor powder and a carbon source, roasting in an inert gas atmosphere, and then grinding to obtain LiMn 1-x Mg x PO 4 the/C cathode material, wherein x = 0.01-0.15.
Chinese patent publication No. CN103413940A discloses a synthesis method of nano-lithium manganese phosphate as a lithium ion battery anode material, which comprises the steps of firstly dissolving phosphoric acid in deionized water to obtain a phosphoric acid solution, adding PEG400 in a stirring state to obtain a PEG400 phosphoric acid mixed solution, then dissolving lithium hydroxide in deionized water to obtain a lithium hydroxide aqueous solution, adding the lithium hydroxide aqueous solution into the PEG400 phosphoric acid mixed solution under stirring to obtain a white emulsion, dissolving manganese sulfate in deionized water to prepare a manganese sulfate solution, adding the manganese sulfate aqueous solution into the obtained white emulsion under a stirring state to obtain a precursor emulsion, placing the precursor emulsion into a microwave reactor, controlling the temperature to be 140-180 ℃ to perform microwave reaction for 5-20 min, centrifuging, washing and drying to obtain the nano-lithium manganese phosphate as the lithium ion battery anode material.
Chinese patent publication No. CN102956887A discloses a preparation method of a nano-scale lithium manganese phosphate anode material, wherein a lithium source, a manganese source, a phosphorus source and a doping element compound are mixed according to a molar ratio of (0.9-1): (0.9-1): (0.9-1): (0-0.1) preparing a solution, adding a complexing agent, and adding a carbon source into the solution to obtain a uniform colloid; drying the colloid to obtain precursor powder, heating the precursor powder in a protective atmosphere to obtain nano powder, and sintering the nano powder in the protective atmosphere to obtain the nano lithium manganese phosphate anode material.
The above-mentioned patent discloses different methods for synthesizing lithium manganese phosphate or iron-doped lithium manganese phosphate material, but the compaction density of the material is not improved.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a preparation method of a high-compaction-density lithium manganese iron phosphate/carbon composite anode material, the method prepares nano spherical particles by a three-step sintering synthesis method, the electrochemical properties such as discharge capacity and the like can be greatly improved, the product particles are regular in shape, reasonable in size distribution and smaller in particle gap, and the compaction density is greatly improved (reaching 2.8g cm) -3 Above).
The invention is realized in such a way that a preparation method of the high-compaction-density lithium manganese iron phosphate/carbon composite anode material has a chemical general formula as follows: liMn x Fe y PO 4 /C, wherein x is more than or equal to 0.5 and less than or equal to 0.9, and x + y =1;
the preparation method comprises the following steps:
1) Diluting phosphoric acid to a mass concentration of 2-55% for later use, adding a manganese source, an iron source, a dispersing agent and deionized water into a sealable container, and introducing protective gas into the container;
2) Slowly adding the diluted phosphoric acid solution into a sealed container to generate ferromanganese phosphate precipitate, aging for 10-20 days, and adjusting the pH value to be stable at 2.0-5.0 at any time to ensure that the ferromanganese phosphate precipitate is uniformly nucleated;
3) Washing the formed precipitate for 3-5 times by using deionized water with the mass of 5-50 times, then drying at the temperature of 60-80 ℃ in vacuum, and then sintering at high temperature for the first time in a protective gas atmosphere to form spherical particles A with the particle size of 1-10 mu m;
4) Taking monohydrate lithium hydroxide LiOH.H 2 O is prepared into a solution with the mass concentration of 1-15%, the spherical particles A are added into the solution, and after spray drying, the spherical particles B are obtained by secondary sintering at high temperature in a protective gas atmosphere;
5) Preparing glucose into a solution with the mass concentration of 30-70%, adding the spherical particles B into the solution, spray-drying, and sintering at high temperature for the third time in a protective gas atmosphere to obtain the nano spherical lithium manganese iron phosphate/carbon (LiMn) x Fe y PO 4 and/C) material.
In the above technical solution, preferably, the manganese source is manganese sulfate (MnSO) 4 ) Manganese chloride (MnCl) 2 ) Manganese oxalate (MnC) 2 O 4 ) And manganese acetate (Mn (CH) 3 COO) 2 ) One or more of them.
In the above technical solution, preferably, the iron source is ferrous sulfate (FeSO) 4 ) Ferrous chloride (FeCl) 2 ) Iron oxalate (FeC) 2 O 4 ) And ferrous acetate (Fe (CH) 3 COO) 2 ) One or more of them.
In the above technical solution, preferably, the dispersant is one or more of polyethylene glycol 400, polyethylene wax, stearamide and glycerol monostearate.
In the above technical solution, preferably, the mass ratio of the dispersant to the deionized water is (1-5): (70-150).
In the above technical solution, preferably, in the steps 1), 3), 4), and 5), the protective gas is argon or nitrogen.
In the above technical solution, preferably, in the steps 4) and 5), a spray dryer or a centrifugal spray dryer or a pressure spray dryer is used to spray-dry the precursor material, wherein the inlet temperature of the spray dryer is 200 to 350 ℃, and the outlet temperature of the spray dryer is 60 to 120 ℃.
In the above technical solution, preferably, in the steps 3), 4), and 5), the sintering temperature is 700 to 800 ℃ and the time is 4 to 12 hours.
The invention has the advantages and positive effects that:
(1) The method adopts a coprecipitation method to synthesize the ferromanganese source precursor, reaction conditions are easy to control in the reaction process, and the product has good performance repeatability.
(2) The prepared lithium iron manganese phosphate/carbon composite positive electrode material is nano-particles, is uniform in size distribution, and can effectively reduce the separation and embedding paths in the lithium ion charging and discharging process; the anode material has the advantages of high specific capacity, high working voltage, good rate capability, good cycling stability and the like.
(3) The lithium iron manganese phosphate/carbon composite anode material prepared by coprecipitation-three-step sintering synthesis can control the shape and size of particles in each step, and can improve the material compaction density which reaches 2.8g cm -3 The above.
(4) The main raw materials used in the invention have rich sources and low price, and the invention has good application prospect.
Drawings
Fig. 1 is an SEM image of a high-compaction-density lithium iron manganese phosphate/carbon composite positive electrode material prepared in example 1 of the present invention;
fig. 2 is an XRD chart of the high-compacted-density lithium iron manganese phosphate/carbon composite positive electrode material prepared in example 1 of the present invention;
fig. 3 is a charge-discharge performance curve diagram of the high-compaction-density lithium iron manganese phosphate/carbon composite positive electrode material prepared in example 1 of the present invention at a magnification of 0.2C within a range of 2.5 to 4.5V.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The embodiment of the invention provides a high-compaction-density lithium manganese iron phosphate/carbon composite anodeThe preparation method of the cathode material comprises the following steps: liMn x Fe y PO 4 /C, wherein x is more than or equal to 0.5 and less than or equal to 0.9, and x + y =1;
the preparation method comprises the following steps:
1) Diluting phosphoric acid to a mass concentration of 2-55% for later use, adding a manganese source, an iron source, a dispersing agent and deionized water into a sealable container, and introducing protective gas into the container;
2) Slowly adding the diluted phosphoric acid solution into a sealed container to generate ferromanganese phosphate precipitate, aging for 10-20 days, and adjusting the pH value to be stable at 2.0-5.0 at any time to ensure that the ferromanganese phosphate precipitate is uniformly nucleated;
3) Washing the formed precipitate for 3-5 times by using deionized water with the mass of 5-50 times, then drying at the temperature of 60-80 ℃ in vacuum, and then sintering at high temperature for the first time in a protective gas atmosphere to form spherical particles A with the particle size of 1-10 mu m;
4) Taking monohydrate lithium hydroxide LiOH.H 2 O is prepared into a solution with the mass concentration of 1-15%, the spherical particles A are added into the solution, and after spray drying, the spherical particles B are sintered for the second time at high temperature in a protective gas atmosphere;
5) Preparing glucose into a solution with the mass concentration of 30-70%, adding the spherical particles B into the solution, spray-drying, and sintering at high temperature for the third time in a protective gas atmosphere to obtain the nano spherical lithium manganese iron phosphate/carbon (LiMn) x Fe y PO 4 /C) materials.
The manganese source is manganese sulfate (MnSO) 4 ) Manganese chloride (MnCl) 2 ) Manganese oxalate (MnC) 2 O 4 ) And manganese acetate (Mn (CH) 3 COO) 2 ) One or more of them.
The iron source is ferrous sulfate (FeSO) 4 ) Ferrous chloride (FeCl) 2 ) Iron oxalate (FeC) 2 O 4 ) And ferrous acetate (Fe (CH) 3 COO) 2 ) One or more of them.
The dispersing agent is one or more of polyethylene glycol 400, polyethylene wax, stearamide and stearic acid monoglyceride.
The mass ratio of the dispersing agent to the deionized water is (1-5): (70-150).
In the steps 1), 3), 4) and 5), the protective gas is argon or nitrogen.
In the steps 4) and 5), spray drying is carried out on the precursor material by adopting a spray dryer or a centrifugal spray dryer or a pressure spray dryer, wherein the inlet temperature of the spray drying is 200-350 ℃, and the outlet temperature of the spray drying is 60-120 ℃.
In the steps 3), 4) and 5), the sintering temperature is 700-800 ℃ and the time is 4-12 h.
Example 1
1) Weighing 28.7ml of 85% phosphoric acid, slowly adding 200ml of deionized water, diluting to obtain a solution, adding 45.30g of manganese sulfate MnSO into a sealed container 4 55.61g of ferrous sulfate heptahydrate FeSO 4 ·7H 2 O, 4g of polyethylene glycol 400 and 100ml of deionized water, and introducing a nitrogen protective gas into the container.
2) Slowly adding diluted phosphoric acid into a sealed container to generate ferromanganese phosphate precipitate, aging for 15 days, and adjusting the pH value to 4.0 at any time to ensure that the ferromanganese phosphate precipitate is uniformly nucleated.
3) The precipitate formed was washed 4 times with 10ml of deionized water and then dried under vacuum at 60 ℃. Then sintering for 5 hours at the high temperature of 750 ℃ in the atmosphere of nitrogen protection gas to form spherical particles A with the particle size of 1-10 mu m.
4) 20.98g of lithium hydroxide monohydrate LiOH.H 2 And O, preparing a solution with the mass concentration of 10%, adding the spherical particles A into the solution, spray-drying at the inlet temperature of 200-350 ℃ and the outlet temperature of 60-120 ℃, and then sintering for 5 hours at the high temperature of 750 ℃ in a nitrogen atmosphere to obtain the spherical particles B.
5) Preparing 17.09g of glucose into a 50% mass concentration solution, adding the spherical particles B into the solution, spray-drying at an inlet temperature of 200-350 ℃ and an outlet temperature of 60-120 ℃, and sintering at a high temperature of 750 ℃ for 5 hours in a nitrogen protective atmosphere to obtain the nano spherical lithium manganese iron phosphate/carbon (LiMn) 0.6 Fe 0.4 PO 4 /C) composite positive electrode material.
Example 2
1) 28.7ml of 85% phosphoric acid was weighed and slowly added to 200ml of deionized water to dilute the solution and prepare a solution for use, and 37.77g of MnCl dichloride was added to a sealed container 2 25.35g of FeCl 2 4g of polyethylene glycol 400 and 100ml of deionized water, and a nitrogen blanket was passed through the vessel.
2) Slowly adding diluted phosphoric acid into a sealed container to generate ferromanganese phosphate precipitate, aging for 12 days, and adjusting the pH value to 4.0 at any time to ensure that the ferromanganese phosphate precipitate is uniformly nucleated.
3) The precipitate formed was washed 4 times with 15ml of deionized water and then dried at 70 ℃ under vacuum. Then sintering for 8 hours at high temperature of 720 ℃ in the atmosphere of nitrogen protection gas to form spherical particles A with the particle size of 1-10 mu m.
4) 20.98g of lithium hydroxide monohydrate LiOH.H 2 And O, preparing a solution with the mass concentration of 10%, adding the spherical particles A into the solution, spray-drying at the inlet temperature of 200-350 ℃ and the outlet temperature of 60-120 ℃, and then sintering for 8 hours at the high temperature of 720 ℃ in a nitrogen atmosphere to obtain the spherical particles B.
5) Preparing 13.31g of glucose into a 50% mass concentration solution, adding the spherical particles B into the solution, spray-drying at 200-350 ℃ of the spray-drying inlet temperature and 60-120 ℃ of the spray-drying outlet temperature, and then sintering for 8 hours at 720 ℃ for the third time in a nitrogen protective atmosphere to obtain the nano spherical lithium iron manganese phosphate/carbon (LiMn) 0.6 Fe 0.4 PO 4 /C) composite positive electrode material.
Example 3
1) Weighing 28.7ml85% phosphoric acid, slowly adding into 200ml deionized water, diluting to obtain solution, adding 42.89g manganese oxalate MnSO into a sealed container 4 28.77g of ferrous oxalate FeSO 4 ·7H 2 O, 4g of polyethylene glycol 400 and 100ml of deionized water, and introducing a nitrogen protective gas into the container.
2) Slowly adding diluted phosphoric acid into a sealed container to generate ferromanganese phosphate precipitate, aging for 18 days, and adjusting the pH value to 4.0 at any time to ensure that the ferromanganese phosphate precipitate is uniformly nucleated.
3) The precipitate formed was washed 5 times with 20ml of deionized water and then dried under vacuum at 80 ℃. Then sintering for the first time at 780 ℃ in a nitrogen protective atmosphere for 4h to form spherical particles A with the particle size of 1-10 mu m.
4) 20.98g of lithium hydroxide monohydrate LiOH.H 2 And O, preparing a solution with the mass concentration of 10%, adding the spherical particles A into the solution, spray-drying at the inlet temperature of 200-350 ℃ and the outlet temperature of 60-120 ℃, and then sintering for 4 hours at the high temperature of 780 ℃ in a nitrogen atmosphere to obtain the spherical particles B.
5) Preparing 14.16g of glucose into a 50% mass concentration solution, adding the spherical particles B into the solution, spray-drying at the inlet temperature of 200-350 ℃ and the outlet temperature of 60-120 ℃, and then sintering for the third time at the high temperature of 780 ℃ in a nitrogen protective atmosphere for 4 hours to obtain the nano spherical lithium manganese iron phosphate/carbon (LiMn) 0.6 Fe 0.4 PO 4 /C) composite cathode material.
Performance testing
The nano-spherical lithium iron manganese phosphate/carbon (LiMn) prepared in example 1 0.6 Fe 0.4 PO 4 and/C) testing the composite positive electrode material. FIG. 1 shows the nano-sized spherical lithium iron manganese phosphate/carbon (LiMn) prepared in example 1 0.6 Fe 0.4 PO 4 the/C) scanning electron microscope image of the composite cathode material shows that the secondary particles are spherical and are distributed in different particle sizes, and the particle size range of the secondary particles is 2-15 mu m. The secondary particle balls are formed by stacking primary particles, and the primary particles are tightly connected and almost have no gaps.
FIG. 2 shows the nano-sized spherical lithium iron manganese phosphate/carbon (LiMn) prepared in example 1 0.6 Fe 0.4 PO 4 The XRD pattern of the/C) composite anode material can be seen from figure 2, and the peak position of the pattern is matched with the standard PDF card of lithium iron manganese phosphate.
FIG. 3 shows the nano-sized spherical lithium iron manganese phosphate/carbon (LiMn) prepared in example 1 0.6 Fe 0.4 PO 4 /C) composite positive electrode material, as can be seen from FIG. 3, the charge-discharge performance curve diagram is in the range of 2.5-4.5V at 0.2C rate,the specific discharge capacity reaches 154mAh/g. With Li + Compared with Li, the material has two pairs of typical charge-discharge voltage platforms at about 4.1V and 3.5V, which respectively correspond to Mn 3+ /Mn 2+ And Fe 3+ /Fe 2+ Oxidation-reduction reaction of (1).
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: it is to be understood that modifications may be made to the technical solutions described in the foregoing embodiments, or some or all of the technical features may be equivalently replaced, and the modifications or the replacements may not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (6)
1. A preparation method of a high-compaction-density lithium manganese iron phosphate/carbon composite positive electrode material is characterized by comprising the following steps of: the chemical general formula of the lithium iron manganese phosphate/carbon composite anode material is as follows: liMn x Fe y PO 4 /C, wherein x is more than or equal to 0.5 and less than or equal to 0.9, x + y=1;
the preparation method comprises the following steps:
1) Diluting phosphoric acid to a mass concentration of 2-55% for later use, adding a manganese source, an iron source, a dispersing agent and deionized water into a sealable container, and introducing protective gas into the container;
2) Slowly adding the diluted phosphoric acid solution into a sealed container to generate ferromanganese phosphate precipitate, aging for 10 to 20 days, and adjusting the pH value to be stable at 2.0 to 5.0 at any time to ensure that the ferromanganese phosphate precipitate forms cores uniformly;
3) Washing the formed precipitate for 3-5 times by using deionized water with the mass being 5-50 times that of the precipitate, drying at the temperature of 60-80 ℃ in vacuum, and then sintering at high temperature for the first time in a protective gas atmosphere to form spherical particles A with the particle size being 1-10 mu m;
4) Taking monohydrate lithium hydroxide LiOH.H 2 O, preparing a solution with the mass concentration of 1-15%, adding the spherical particles A into the solution, spray-drying, and sintering at a high temperature for the second time in a protective gas atmosphere to obtain spherical particles B;
5) Taking glucosePreparing a solution with the mass concentration of 30-70%, adding the spherical particles B into the solution, spray-drying, and sintering at high temperature for the third time in a protective gas atmosphere to obtain the nano spherical lithium manganese iron phosphate/carbon (LiMn) x Fe y PO 4 /C) composite positive electrode material of said lithium iron manganese phosphate/carbon (LiMn) x Fe y PO 4 The compacted density of the/C) composite cathode material is 2.8g/cm 3 ；
In the steps 1), 3), 4) and 5), the protective gas is argon or nitrogen;
in the steps 3), 4) and 5), the sintering temperature is 700-800 ℃ and the time is 4-12 h.
2. The method for preparing the high-compaction-density lithium iron manganese phosphate/carbon composite cathode material according to claim 1, wherein the method comprises the following steps: the manganese source is manganese sulfate (MnSO) 4 ) Manganese chloride (MnCl) 2 ) Manganese oxalate (MnC) 2 O 4 ) And manganese acetate (Mn (CH) 3 COO) 2 ) One or more of them.
3. The method for preparing the high-compaction-density lithium iron manganese phosphate/carbon composite cathode material according to claim 1, wherein the method comprises the following steps: the iron source is ferrous sulfate (FeSO) 4 ) Ferrous chloride (FeCl) 2 ) Iron oxalate (FeC) 2 O 4 ) And ferrous acetate (Fe (CH) 3 COO) 2 ) One or more of them.
4. The method for preparing the high-compaction-density lithium iron manganese phosphate/carbon composite cathode material according to claim 1, wherein the method comprises the following steps: the dispersing agent is one or more of polyethylene glycol 400, polyethylene wax, stearamide and stearic acid monoglyceride.
5. The method for preparing the high-compaction-density lithium iron manganese phosphate/carbon composite cathode material according to claim 1, wherein the method comprises the following steps: the mass ratio of the dispersing agent to the deionized water is (1~5): (70 to 150).
6. The method for preparing the high-compaction-density lithium iron manganese phosphate/carbon composite cathode material according to claim 1, wherein the method comprises the following steps: and in the steps 4) and 5), spray drying the precursor material by using a spray dryer or a centrifugal spray dryer or a pressure spray dryer, wherein the inlet temperature of the spray drying is 200 to 350 ℃, and the outlet temperature of the spray drying is 60 to 120 ℃.
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| CN115403023A (en) * | 2022-11-01 | 2022-11-29 | 浙江格派钴业新材料有限公司 | Method for preparing lithium iron manganese phosphate by supercritical hydrothermal method assisted spray drying |
| CN115947327A (en) * | 2023-02-07 | 2023-04-11 | 湖北亿纬动力有限公司 | Lithium manganese iron phosphate cathode material and preparation method and application thereof |
| CN116154156B (en) * | 2023-04-18 | 2023-06-30 | 江苏集萃分子工程研究院有限公司 | Spherical lithium iron manganese phosphate positive electrode material and preparation method thereof |
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