CN116924376A - Method for preparing high-compaction and high-conductivity lithium iron phosphate based on bimodal particle size ferric phosphate - Google Patents

Method for preparing high-compaction and high-conductivity lithium iron phosphate based on bimodal particle size ferric phosphate Download PDF

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CN116924376A
CN116924376A CN202311198766.0A CN202311198766A CN116924376A CN 116924376 A CN116924376 A CN 116924376A CN 202311198766 A CN202311198766 A CN 202311198766A CN 116924376 A CN116924376 A CN 116924376A
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iron phosphate
particle size
lithium iron
compaction
bimodal particle
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CN116924376B (en
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孙丽媛
张泽彤
赵国庆
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BTR Tianjin Nano Material Manufacture Co Ltd
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Abstract

The invention discloses a method for preparing high-compaction high-conductivity lithium iron phosphate based on bimodal particle size ferric phosphate. The preparation method of the lithium iron phosphate can effectively inhibit the abnormal growth of primary particles in the sintering process on the basis of the iron phosphate with a bimodal particle size structure, improves the conductivity, and has high compaction density and high capacity without improving the sintering temperature; meanwhile, the preparation process is high in operability and suitable for large-scale industrialized application.

Description

Method for preparing high-compaction and high-conductivity lithium iron phosphate based on bimodal particle size ferric phosphate
Technical Field
The invention belongs to the field of preparation of lithium iron phosphate, and particularly relates to a method for preparing high-compaction and high-conductivity lithium iron phosphate based on bimodal particle size ferric phosphate.
Background
Most of the active materials in the positive electrode material of the lithium ion battery are lithium-containing transition metal oxides. Currently, research on cathode materials is mainly focused on LiCoO 2 、LiNiO 2 、LiMn 2 O 2 、LiFePO 4 Etc.
Wherein, liFePO 4 The raw materials are wide in source, low in price, nontoxic, good in environmental compatibility, good in thermal stability, good in cycle performance and good in safety when used as the positive electrode material, and the material is considered as a new generation positive electrode material of lithium ion batteries. LiFePO 4 There are two types of sources, one is lithium iron phosphate in nature, but LiFePO 4 The content of (2) is not high, and the electrochemical performance is poor due to the influence of impurities; the other is artificial LiFePO which is most studied at present 4 The synthesis methods are largely classified into a solid phase method and a liquid phase method. The high-temperature solid phase method in the solid phase method is easy to industrialize due to relatively simple process, and is used for preparing LiFePO at present 4 Is a main method of (2). The reaction raw materials are mainly lithium salt, ammonium hydrogen phosphate and iron compounds, and are synthesized by uniformly mixing the raw materials according to stoichiometric ratio, and then sintering at high temperature (usually, pre-calcining at 300-350 ℃ and then calcining at 500-800 ℃) under the condition of inert atmosphere or reducing atmosphere.
However, in actual production, liFePO was found 4 There are two drawbacks: firstly, the electron conductivity is low, which is not beneficial to reversible charge and discharge; and secondly, the lithium ion conductivity is low, which is unfavorable for high-rate discharge. In order to improve the conductivity, liFePO has been used 4 Carbon coating is carried out or performances of the alloy are modified by doping Mn, mg, al, ti, zr, nb, W and the like.
The carbon coating can also inhibit abnormal growth of primary particles, thereby ensuring the number of small particles to ensure conductivity. But at the same time the small grain grains will lead to LiFePO 4 Resulting in a low specific volumetric capacity made from it, which in practice would hinder the LiFePO 4 Application of materials. Thus, there is a need for a new LiFeP with high conductivity and high compaction densityO 4 The technical barriers that the prior art and the prior art cannot be simultaneously combined are solved.
Disclosure of Invention
The invention aims to: the invention aims to solve the technical problem of providing a novel lithium iron phosphate positive electrode material with high conductivity and high compaction density.
The technical scheme is as follows: the invention relates to a method for preparing high-compaction and high-conductivity lithium iron phosphate based on bimodal particle size ferric phosphate, which is characterized by comprising the following steps:
(1) Preparing iron phosphate with bimodal particle size: preparing ferric nitrate and disodium hydrogen phosphate into ferric nitrate solution and disodium hydrogen phosphate solution respectively according to the molar ratio of 1:1-1.5, regulating the pH value of the ferric nitrate solution to 1-1.5, adding the disodium hydrogen phosphate solution into the ferric nitrate solution, uniformly mixing, stirring, adding a dispersing agent, silica aerogel and a homogeneous phase precipitator, reacting at the temperature of 90-110 ℃ until white precipitation appears, cooling to room temperature, filtering, washing and drying to obtain the ferric phosphate powder with a bimodal particle size structure;
(2) Preparing lithium iron phosphate: adding ferric phosphate powder, a lithium source and a carbon source into a solvent, dispersing, grinding and spray-drying to obtain a lithium iron phosphate precursor, and sintering the precursor for 8-12h in an inert atmosphere at 770-790 ℃ to obtain the lithium iron phosphate.
According to the invention, when the iron phosphate is prepared, the dispersing agent and the silica aerogel are introduced, so that the silica aerogel can be uniformly and fully dispersed in an iron phosphate system, and further when iron phosphate grains are formed, the silica aerogel uniformly filled in the iron phosphate system can limit the growth of the grains positioned at the periphery of the iron phosphate system, so that the finally prepared iron phosphate has a bimodal structure with uniformly distributed size, the compaction density of the iron phosphate with large particle size can be improved, and the conductivity of the iron phosphate with small particle size can be improved, and double effects are obtained; meanwhile, the lithium iron phosphate prepared based on the iron phosphate with the bimodal structure still has the compaction density under the condition of not increasing the sintering temperature, so that the capacitance is increased, and meanwhile, the abnormal growth of primary particles is inhibited by combining with the coating of a carbon source, so that the conductivity is further improved; in addition, the pore structure of the silica aerogel can provide more ion transmission channels, so that the lithium ion battery is endowed with higher energy density and capacity.
Further, in the step (1) of the preparation method, the addition amount of the dispersing agent is 3-5% of the mass of the ferric nitrate.
Further, in step (1) of the preparation method, the dispersant includes hydroxymethyl cellulose, hydroxyethyl cellulose, or gelatin.
Further, in the step (1) of the preparation method, the addition amount of the silica aerogel is 10-15% of the mass of the ferric nitrate.
Further, in the step (1) of the preparation method, the mol ratio of the homogeneous phase precipitator to ferric nitrate is 1.2-1.5:1, and the homogeneous phase precipitator is urea or hexamethylenetetramine.
Further, in the step (2) of the preparation method, the molar ratio of Li to Fe in the lithium source and the ferric phosphate powder is 1.01-1.06:1.
Further, in the step (2) of the preparation method, the carbon source is a polyethylene glycol and sucrose complex with a mass ratio of 1:1-2.
According to the invention, a carbon source compounded by polyethylene glycol and sucrose is adopted, so that a three-dimensional network can be formed after pyrolysis, lithium iron phosphate particles can be completely coated, and the appearance of large particles after high-temperature fusion is inhibited.
Further, in the step (2) of the preparation method, the addition amount of the carbon source is 8-16% of the mass of the ferric phosphate.
Further, in the step (2) of the preparation method, the solvent is water or ethanol.
Further, in the step (2) of the preparation method, the inlet air temperature of the spray drying is 200-240 ℃, and the outlet temperature is 90-110 ℃.
The beneficial effects are that: compared with the prior art, the invention has the remarkable advantages that: the high-compaction and high-conductivity lithium iron phosphate can effectively inhibit abnormal growth of primary particles in the sintering process on the basis of the iron phosphate with a double-peak granularity structure, improves the conductivity, and has high compaction density and high capacity without improving the sintering temperature; meanwhile, the preparation process is high in operability and suitable for large-scale industrialized application.
Drawings
FIG. 1 is a particle size distribution diagram of iron phosphate prepared in example 1 of the present invention;
FIG. 2 is an SEM photograph of iron phosphate of example 1 of the present invention, at 5000 magnification;
fig. 3 is an SEM image of lithium iron phosphate prepared in example 1 of the present invention, at 5000 magnification;
FIG. 4 is a particle size distribution diagram of iron phosphate prepared in comparative example 1 of the present invention;
fig. 5 is an SEM picture of iron phosphate prepared in comparative example 1 of the present invention, at 5000 magnification;
fig. 6 is an SEM image of lithium iron phosphate prepared in comparative example 1 of the present invention, at a magnification of 5000.
Detailed Description
The technical scheme of the invention is further described in detail below with reference to the accompanying drawings.
Example 1:
the preparation method of the iron phosphate of the embodiment 1 comprises the following steps:
(1) Fully dissolving ferric nitrate in water to prepare ferric nitrate solution, fully dissolving disodium hydrogen phosphate in water to prepare disodium hydrogen phosphate solution, wherein the molar ratio of ferric nitrate to disodium hydrogen phosphate is 1:1 (wherein, ferric nitrate is 1 mol);
(2) Adjusting the pH value of the ferric nitrate solution to 1-1.5 by adopting nitric acid, adding the disodium hydrogen phosphate solution into the ferric nitrate solution, and uniformly mixing to prepare a mixed solution;
(3) Adding hydroxymethyl cellulose, silica aerogel and urea into the mixed solution while stirring, reacting at 100 ℃ until white precipitation appears, cooling to room temperature, filtering, washing and drying to obtain ferric phosphate powder with a bimodal particle size structure; wherein the adding amount of the hydroxymethyl cellulose is 4% of the mass of the ferric nitrate, the adding amount of the silicon dioxide aerogel is 12% of the mass of the ferric nitrate, and the molar ratio of urea to the ferric nitrate is 1.3:1.
The iron phosphate prepared in this example 1 was subjected to morphology and particle size distribution characterization, and the results obtained are shown in fig. 1 and 2. As can be seen from FIG. 1, the size particles of the iron phosphate prepared by the method are uniformly distributed and are in bimodal distribution. And further from the SEM image of fig. 2, the secondary particles of the lithium iron phosphate precursor are spherical or spheroid.
The preparation method of the lithium iron phosphate of the embodiment 1 comprises the following steps:
(1) Adding ferric phosphate, lithium carbonate and a carbon source into water to prepare slurry, wherein the solid content of the slurry is 40%; wherein the molar ratio of Li to Fe in the lithium carbonate to the ferric phosphate is 1.03:1; the carbon source is a polyethylene glycol and sucrose compound with the mass ratio of 1:1, and the addition amount of the polyethylene glycol and sucrose compound is 12.5% of the mass of the ferric phosphate;
(2) Dispersing and grinding the prepared slurry so that the grinding particle size reaches 425nm, and then carrying out spray drying on the slurry to obtain a lithium iron phosphate precursor, wherein the air inlet temperature of spray drying is 240 ℃, and the outlet temperature is 100 ℃;
(3) And (3) placing the lithium iron phosphate precursor in a graphite crucible, placing in a nitrogen-protected tube furnace, heating to 790 ℃ at a heating rate of 2.5 ℃/min, preserving heat for 10 hours, cooling to room temperature, and carrying out airflow powder to obtain the D50=1.5 mu m lithium iron phosphate anode material.
The lithium iron phosphate prepared in this example 1 was structurally characterized, and the results obtained are shown in fig. 3 below. According to the graph, the lithium iron phosphate prepared by the method has uniform particle size distribution and good carbon coating effect, and has promotion effect on compaction and capacity. And further examined for electrochemical properties, the results obtained are shown in Table 1 below. As is clear from Table 1, the 0.1C discharge capacity of the prepared positive electrode material reaches 156mAh/g, and the compacted density of the positive electrode material is 2.652 g/cm 3
Comparative example 1:
the iron phosphate of comparative example 1 was prepared in substantially the same manner as in example 1, except that no silica aerogel was added in preparing the iron phosphate, and specifically comprising the steps of:
(1) Fully dissolving ferric nitrate in water to prepare ferric nitrate solution, fully dissolving disodium hydrogen phosphate in water to prepare disodium hydrogen phosphate solution, wherein the molar ratio of ferric nitrate to disodium hydrogen phosphate is 1:1;
(2) Adjusting the pH value of the ferric nitrate solution to 1-1.5 by adopting nitric acid, adding the disodium hydrogen phosphate solution into the ferric nitrate solution, and uniformly mixing to prepare a mixed solution;
(3) Adding hydroxymethyl cellulose and urea into the mixed solution while stirring, reacting at 100 ℃ until white precipitation appears, cooling to room temperature, filtering, washing and drying to obtain ferric phosphate powder with a bimodal particle size structure; wherein, the adding amount of the hydroxymethyl cellulose is 4% of the mass of the ferric nitrate, and the mol ratio of urea to the ferric nitrate is 1.3:1.
The morphology and particle size distribution of the iron phosphate prepared in comparative example 1 were characterized, and the obtained results are shown in fig. 4 and 5. As can be seen from fig. 4, the particle size of the iron phosphate prepared in this comparative example is normally distributed, and no double peaks exist. And further from the SEM image of fig. 5, it can be seen that the secondary particles of the lithium iron phosphate precursor are spherical or spheroid.
The preparation method of the lithium iron phosphate of comparative example 1 is the same as that of example 1:
(1) Adding ferric phosphate, lithium carbonate and a carbon source into water to prepare slurry, wherein the solid content of the slurry is 40%; wherein the molar ratio of Li to Fe in the lithium carbonate to the ferric phosphate is 1.03:1; the carbon source is a polyethylene glycol and sucrose compound with the mass ratio of 1:1, and the addition amount of the polyethylene glycol and sucrose compound is 12.5% of the mass of the ferric phosphate;
(2) Dispersing and grinding the prepared slurry so that the grinding particle size reaches 425nm, and then carrying out spray drying on the slurry to obtain a lithium iron phosphate precursor, wherein the air inlet temperature of spray drying is 240 ℃, and the outlet temperature is 100 ℃;
(3) And (3) placing the lithium iron phosphate precursor in a graphite crucible, placing in a nitrogen-protected tube furnace, heating to 790 ℃ at a heating rate of 2.5 ℃/min, preserving heat for 10 hours, cooling to room temperature, and carrying out airflow powder to obtain the D50=1.2 mu m lithium iron phosphate anode material.
The lithium iron phosphate prepared in comparative example 1 was subjected to structural characterization, and the obtainedThe results are shown in FIG. 6 below. From this figure, it is clear that the comparative example 1 has poor uniformity of particle size distribution and good carbon coating effect, which is disadvantageous for compaction and has an improved capacity. And further examined for electrochemical properties, the results obtained are shown in Table 1 below. As can be seen from Table 1, the 0.1C discharge capacity of the prepared cathode material reaches 161mAh/g, and the compaction density of the material is measured to be 2.355 g/cm 3
Comparative example 2:
the iron phosphate of comparative example 2 was prepared in the same manner as in comparative example 1
The preparation method of the lithium iron phosphate of comparative example 2 is basically the same as comparative example 1, except that the carbon source is added in the following amounts:
(1) Adding ferric phosphate, lithium carbonate and a carbon source into water to prepare slurry, wherein the solid content of the slurry is 40%; wherein the molar ratio of Li to Fe in the lithium carbonate to the ferric phosphate is 1.03:1; the carbon source is a polyethylene glycol and sucrose compound with the mass ratio of 1:1, and the adding amount of the polyethylene glycol and sucrose compound is 16% of the mass of the ferric phosphate;
(2) Dispersing and grinding the prepared slurry so that the grinding particle size reaches 425nm, and then carrying out spray drying on the slurry to obtain a lithium iron phosphate precursor, wherein the air inlet temperature of spray drying is 240 ℃, and the outlet temperature is 100 ℃;
(3) And (3) placing the lithium iron phosphate precursor in a graphite crucible, placing in a nitrogen-protected tube furnace, heating to 790 ℃ at a heating rate of 2.5 ℃/min, preserving heat for 10 hours, cooling to room temperature, and carrying out airflow powder to obtain the D50=1.4 mu m lithium iron phosphate anode material.
The lithium iron phosphate prepared in comparative example 2 was subjected to electrochemical performance test, and the obtained results are shown in table 1 below. As can be seen from Table 1, the 0.1C discharge capacity of the prepared cathode material reaches 163mAh/g, and the compacted density of the material is 2.301 g/cm 3
Example 2:
the preparation method of the iron phosphate of the embodiment 2 comprises the following steps:
(1) Fully dissolving ferric nitrate in water to prepare ferric nitrate solution, fully dissolving disodium hydrogen phosphate in water to prepare disodium hydrogen phosphate solution, wherein the molar ratio of ferric nitrate to disodium hydrogen phosphate is 1:1.5 (wherein, ferric nitrate is 1 mol);
(2) Adjusting the pH value of the ferric nitrate solution to 1-1.5 by adopting nitric acid, adding the disodium hydrogen phosphate solution into the ferric nitrate solution, and uniformly mixing to prepare a mixed solution;
(3) Adding hydroxyethyl cellulose, silicon dioxide aerogel and urea into the mixed solution while stirring, reacting at 90 ℃ until white precipitation appears, cooling to room temperature, filtering, washing and drying to obtain ferric phosphate powder with a bimodal particle size structure; the adding amount of the hydroxyethyl cellulose is 3% of the mass of the ferric nitrate, the adding amount of the silicon dioxide aerogel is 10% of the mass of the ferric nitrate, and the molar ratio of urea to the ferric nitrate is 1.2:1.
The preparation method of the lithium iron phosphate of the embodiment 2 comprises the following steps:
(1) Adding ferric phosphate, lithium carbonate and a carbon source into water to prepare slurry, wherein the solid content of the slurry is 40%; wherein, the mol ratio of Li to Fe in the lithium carbonate to the ferric phosphate is 1.01:1; the carbon source is a polyethylene glycol and sucrose compound with the mass ratio of 1:1.5, and the adding amount of the polyethylene glycol and sucrose compound is 16% of the mass of the ferric phosphate;
(8) Dispersing and grinding the prepared slurry so that the grinding particle size reaches 425nm, and then carrying out spray drying on the slurry to obtain a lithium iron phosphate precursor, wherein the air inlet temperature of spray drying is 220 ℃, and the outlet temperature is 90 ℃;
(3) And (3) placing the lithium iron phosphate precursor in a graphite crucible, placing in a nitrogen-protected tube furnace, heating to 770 ℃ at a heating rate of 2.5 ℃/min, preserving heat for 12 hours, cooling to room temperature, and carrying out airflow powder to obtain the D50=1.3 mu m lithium iron phosphate anode material.
The lithium iron phosphate prepared in example 2 was subjected to electrochemical performance test, and the obtained results are shown in table 1 below. As is clear from Table 1, the 0.1C discharge capacity of the prepared positive electrode material reaches 158mAh/g, and the compacted density of the positive electrode material is 2.594 g/cm 3
Example 3:
the preparation method of the iron phosphate of the embodiment 3 comprises the following steps:
(1) Fully dissolving ferric nitrate in water to prepare ferric nitrate solution, fully dissolving disodium hydrogen phosphate in water to prepare disodium hydrogen phosphate solution, wherein the molar ratio of ferric nitrate to disodium hydrogen phosphate is 1:1;
(2) Adjusting the pH value of the ferric nitrate solution to 1-1.5 by adopting nitric acid, adding the disodium hydrogen phosphate solution into the ferric nitrate solution, and uniformly mixing to prepare a mixed solution;
(3) Adding gelatin, silicon dioxide aerogel and hexamethylenetetramine into the mixed solution while stirring, reacting at 110 ℃ until white precipitation appears, cooling to room temperature, filtering, washing and drying to obtain ferric phosphate powder with a bimodal particle size structure; the adding amount of gelatin is 5% of the mass of ferric nitrate, the adding amount of silicon dioxide aerogel is 15% of the mass of ferric nitrate, and the mol ratio of hexamethylenetetramine to ferric nitrate is 1.5:1.
The preparation method of the lithium iron phosphate of the embodiment 3 comprises the following steps:
(1) Adding ferric phosphate, lithium carbonate and a carbon source into ethanol to prepare slurry, wherein the solid content of the slurry is 40%; wherein, the mol ratio of Li to Fe in the lithium carbonate to the ferric phosphate is 1.06:1; the carbon source is a polyethylene glycol and sucrose compound with the mass ratio of 1:2, and the addition amount of the polyethylene glycol and sucrose compound is 8% of the mass of the ferric phosphate;
(8) Dispersing and grinding the prepared slurry so that the grinding particle size reaches 425nm, and then carrying out spray drying on the slurry to obtain a lithium iron phosphate precursor, wherein the air inlet temperature of spray drying is 200 ℃, and the outlet temperature is 110 ℃;
(3) And (3) placing the lithium iron phosphate precursor in a graphite crucible, placing in a nitrogen-protected tube furnace, heating to 780 ℃ at a heating rate of 2.5 ℃/min, preserving heat for 8 hours, cooling to room temperature, and carrying out airflow powder to obtain the D50=1.2 mu m lithium iron phosphate anode material.
The lithium iron phosphate prepared in example 3 was subjected to electrochemical performance test, and the obtained results are shown in table 1 below. As is clear from Table 1, the 0.1C discharge capacity of the prepared positive electrode material reaches 157mAh/g, and the compacted density of the positive electrode material is 2.638 g/cm 3
Table 1 electrochemical performance table of lithium iron phosphate prepared in examples and comparative examples
Examples Density of compaction (g/cm) 3 0.1C discharge capacity (mAh/g) First time efficiency%
Example 1 2.652 156 95.5
Example 2 2.594 158 96
Example 3 2.638 157 95.7
Comparative example 1 2.355 161 98.5
Comparative example 2 2.301 163 99
From the above examples and comparative examples, it is apparent that the compacted density of lithium iron phosphate prepared by using the iron phosphate having a bimodal particle size structure prepared by the present invention is significantly improved, but the difference in discharge capacity is not large. Therefore, the lithium iron phosphate prepared by the method can effectively solve the prior art barriers, and not only can realize excellent conductivity, namely, the capacitance is improved, but also can have extremely high compaction density.

Claims (10)

1. A method for preparing high-compaction and high-conductivity lithium iron phosphate based on bimodal particle size ferric phosphate, which is characterized by comprising the following steps:
(1) Preparing iron phosphate with bimodal particle size: preparing ferric nitrate and disodium hydrogen phosphate into ferric nitrate solution and disodium hydrogen phosphate solution respectively according to the molar ratio of 1:1-1.5, regulating the pH value of the ferric nitrate solution to 1-1.5, adding the disodium hydrogen phosphate solution into the ferric nitrate solution, uniformly mixing, stirring, adding a dispersing agent, silica aerogel and a homogeneous phase precipitator, reacting at the temperature of 90-110 ℃ until white precipitation appears, cooling to room temperature, filtering, washing and drying to obtain the ferric phosphate powder with a bimodal particle size structure;
(2) Preparing lithium iron phosphate: adding ferric phosphate, a lithium source and a carbon source into a solvent, dispersing, grinding and spray-drying to obtain a lithium iron phosphate precursor, and sintering the precursor for 8-12h at 770-790 ℃ in an inert atmosphere to obtain the lithium iron phosphate.
2. The method for preparing high-compaction, high-conductivity lithium iron phosphate based on bimodal particle size iron phosphate according to claim 1, wherein: in the step (1), the addition amount of the dispersing agent is 3-5% of the mass of the ferric nitrate.
3. The method for preparing high-compaction, high-conductivity lithium iron phosphate based on bimodal particle size iron phosphate according to claim 1, wherein: in the step (1), the dispersing agent is hydroxymethyl cellulose, hydroxyethyl cellulose or gelatin.
4. The method for preparing high-compaction, high-conductivity lithium iron phosphate based on bimodal particle size iron phosphate according to claim 1, wherein: in the step (1), the addition amount of the silicon dioxide aerogel is 10-15% of the mass of the ferric nitrate.
5. The method for preparing high-compaction, high-conductivity lithium iron phosphate based on bimodal particle size iron phosphate according to claim 1, wherein: in the step (1), the mol ratio of the homogeneous phase precipitant to ferric nitrate is 1.2-1.5:1, and the homogeneous phase precipitant is urea or hexamethylenetetramine.
6. The method for preparing high-compaction, high-conductivity lithium iron phosphate based on bimodal particle size iron phosphate according to claim 1, wherein: in the step (2), the molar ratio of Li to Fe in the lithium source and the ferric phosphate is 1.01-1.06:1.
7. The method for preparing high-compaction, high-conductivity lithium iron phosphate based on bimodal particle size iron phosphate according to claim 1, wherein: in the step (2), the carbon source is a polyethylene glycol and sucrose complex with a mass ratio of 1:1-2.
8. The method for preparing high-compaction, high-conductivity lithium iron phosphate based on bimodal particle size iron phosphate according to claim 1, wherein: in the step (2), the addition amount of the carbon source is 8-16% of the mass of the ferric phosphate.
9. The method for preparing high-compaction, high-conductivity lithium iron phosphate based on bimodal particle size iron phosphate according to claim 1, wherein: in the step (2), the solvent is water or ethanol.
10. The method for preparing high-compaction, high-conductivity lithium iron phosphate based on bimodal particle size iron phosphate according to claim 1, wherein: in the step (2), the inlet air temperature of the spray drying is 200-240 ℃, and the outlet temperature is 90-110 ℃.
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CN111029571A (en) * 2019-11-22 2020-04-17 贵州唯特高新能源科技有限公司 Preparation method of silicon dioxide uniformly doped iron phosphate
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CN102491302A (en) * 2011-12-15 2012-06-13 湖北万润新能源科技发展有限公司 Battery-grade anhydrous iron phosphate and preparation method thereof
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