Lithium iron phosphate material, preparation method thereof and lithium ion battery
The preparation of lithium iron phosphate materials by wet ball milling and Joule thermal flash evaporation processes solves the problems of uneven mixing and high energy consumption in existing technologies, achieving efficient and uniform lithium iron phosphate production and improving the performance of lithium-ion batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-04
- Publication Date
- 2026-03-10
AI Technical Summary
Existing methods for preparing lithium iron phosphate suffer from problems such as uneven material mixing, wide particle size distribution, high energy consumption, and low production efficiency, making it difficult to meet the needs of large-scale production and performance improvement.
Wet ball milling and Joule heat flash evaporation processes were employed to prepare lithium iron phosphate materials with uniform particle size and narrow particle size distribution by wet ball milling and drying of a mixture of lithium source, iron source, phosphorus source, carbon source and dopants, followed by flash evaporation in a Joule heat equipment. The operating conditions of different flash evaporation chambers were controlled to prepare the materials.
Significantly reducing production energy consumption, improving production efficiency, and enhancing particle size uniformity, lithium iron phosphate materials are suitable for large-scale production. When used in lithium-ion batteries, they exhibit excellent kinetic and low-temperature performance, thus improving battery product quality.
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Figure CN121626952A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a lithium iron phosphate material and a preparation method thereof, and a lithium ion battery. BACKGROUND
[0002] Lithium iron phosphate is a compound used as a positive electrode material of a lithium ion battery. The current industry preparation methods of lithium iron phosphate mainly include solid phase method and liquid phase method. The mainstream process in the solid phase method is carbon thermal reduction method, which has defects of uneven mixing between materials, wide particle size distribution range, poor consistency, and usually needs to go through a complex high-temperature sintering process, which is time-consuming and energy-consuming. The liquid phase method has higher requirements for reaction conditions, complex production equipment, and large production difficulty, and the obtained product has low compacted density.
[0003] Under the background that lithium iron phosphate gradually approaches the theoretical energy density, it is necessary to further improve the preparation process route, reduce the production cost, improve the production efficiency, and improve the product quality, which becomes an important branch of the future development trend of lithium iron phosphate. SUMMARY
[0004] The purpose of the present disclosure is to provide a lithium iron phosphate material and a preparation method thereof, and a lithium ion battery, so as to reduce the production cost of the lithium iron phosphate material, improve the production efficiency, and optimize the performance of the lithium iron phosphate material.
[0005] In order to achieve the above-mentioned purpose, the first aspect of the present disclosure provides a preparation method of a lithium iron phosphate material, which comprises the following steps: mixing raw material mixture containing lithium source, iron source, phosphorus source, carbon source and dopant by wet ball milling and drying to obtain the ball-milled mixture; flash evaporating the ball-milled mixture by joule heat to obtain the lithium iron phosphate material.
[0006] Optionally, the molar ratio of the iron source, the lithium source and the phosphorus source is 1: (1-4): (1-4). The weight ratio of the iron source, the carbon source and the dopant is 100: (0.001-10): (0.0001-0.4). Optionally, the lithium source is at least one selected from lithium oxide, lithium hydroxide, lithium phosphate, lithium carbonate, lithium nitrate, lithium dihydrogen phosphate, lithium formate and lithium acetate.
[0007] Optionally, the iron source is at least one selected from iron, iron phosphate, ferrous sulfate, diiron trioxide, ferrous oxide, ferric oxide, ammonium ferrous sulfate, ferrous sulfate and ferrous phosphate; and / or, The phosphorus source is at least one selected from diaphosphorus pentoxide, phosphoric acid, ammonium dihydrogen phosphate, lithium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium ferrous phosphate and ammonium hydrogen phosphate.
[0008] Optionally, the carbon source is at least one selected from glucose, sucrose, maltose, polyethylene glycol, polyvinyl alcohol, citric acid, acetylene black, carbon nanotubes, and carbon nanofibers; and / or, The dopant is at least one element or compound selected from titanium, manganese, cobalt, vanadium, nickel, aluminum, magnesium, calcium, zinc, silver, and copper.
[0009] Optionally, the conditions for the wet ball milling include: a rotation speed of 100~3000 r / min, a time of 1~24 h, and a temperature of 25~100℃; and / or, The drying conditions include a temperature of 30~100℃ and a time of 1~10h.
[0010] Optionally, the conditions for the Joule flash evaporation include: a current of 1~1000A, a temperature of 600~1200℃, and a time of 10~600s; and / or, The lithium iron phosphate material has a D10 particle size of 0.005~8μm, a D50 particle size of 0.02~10μm, and a D90 particle size of 0.1~12μm.
[0011] Optionally, the Joule heating flash evaporation is carried out in a Joule heating device, which has n flash chambers arranged in parallel, and the operating conditions of the n flash chambers can be controlled independently; The method further includes: dividing the ball-milled mixture into n strands and feeding them into the n flash chambers for Joule thermal flash evaporation to obtain n kinds of lithium iron phosphate materials; wherein, the operating conditions of at least two of the n flash chambers are controlled to be different so that the D50 particle size range of at least two of the n kinds of lithium iron phosphate materials is different. Preferably, n is 8 to 10.
[0012] A second aspect of this disclosure provides a lithium iron phosphate material prepared by the method described in the first aspect of this disclosure.
[0013] In a third aspect, this disclosure provides a lithium-ion battery comprising the lithium iron phosphate material described in the second aspect of this disclosure.
[0014] Through the above technical solution, this disclosure describes a process of wet ball milling and drying a mixture of raw materials containing lithium, iron, phosphorus, and carbon sources, followed by Joule heat flash evaporation to prepare lithium iron phosphate material. This method requires no complex equipment or processes, significantly reduces energy consumption, and improves production efficiency, making it suitable for large-scale production. It also helps improve particle size uniformity and reduce particle size distribution width. The lithium iron phosphate material prepared using this method exhibits excellent kinetic and low-temperature performance in lithium-ion batteries, can adapt to a wide range of battery operating temperatures, and has promising application prospects.
[0015] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description
[0016] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the Joule heating device used in a specific embodiment of the lithium iron phosphate material preparation method provided in this disclosure.
[0017] Explanation of reference numerals in the attached figures 1—Flash chamber. Detailed Implementation
[0018] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.
[0019] According to a first aspect of this disclosure, a method for preparing lithium iron phosphate material is provided, the method comprising the following steps S1-S2: S1. A mixture of raw materials containing lithium source, iron source, phosphorus source, carbon source and dopants is wet ball-milled and dried to obtain a ball-milled mixture; S2. The ball-milled mixture is subjected to Joule heat flash evaporation to obtain lithium iron phosphate material.
[0020] In step S1, the molar ratio of the iron source, the lithium source and the phosphorus source can be 1:(1~4):(1~4), preferably 1:(1.05~2):(1.05~2); the weight ratio of the iron source, the carbon source and the dopant is 100:(0.001~10):(0.0001~0.4), preferably 100:(0.1~1):(0.0001~0.1).
[0021] The lithium source can be at least one selected from lithium oxide, lithium hydroxide, lithium phosphate, lithium carbonate, lithium nitrate, lithium dihydrogen phosphate, lithium formate, and lithium acetate, preferably at least one selected from lithium carbonate, lithium hydroxide, and lithium phosphate. The iron source can be at least one selected from iron, ferric phosphate, ferrous sulfate, ferric oxide, ferrous oxide, magnetite, ferrous ammonium sulfate, ferrous sulfate, and ferrous phosphate, preferably at least one selected from ferric phosphate, ferrous sulfate, and magnetite. The phosphorus source can be at least one selected from phosphorus pentoxide, phosphoric acid, ammonium dihydrogen phosphate, lithium dihydrogen phosphate, diammonium hydrogen phosphate, ferrous ammonium phosphate, and ammonium hydrogen phosphate salt, preferably phosphoric acid and / or diammonium hydrogen phosphate. The carbon source can be at least one selected from glucose, sucrose, maltose, polyethylene glycol (PEG), polyvinyl alcohol (PVA), citric acid, acetylene black, carbon nanotubes, and carbon nanofibers, preferably at least one selected from glucose, polyethylene glycol (PEG), and polyvinyl alcohol (PVA). The dopant may be at least one selected from elements and compounds of titanium, manganese, cobalt, vanadium, nickel, aluminum, magnesium, calcium, zinc, silver, and copper, preferably at least one selected from elements and compounds of manganese, magnesium, vanadium, and titanium.
[0022] The liquid medium used in the wet ball milling can be at least one selected from water, ethanol, and methanol. The amount of liquid medium can be adjusted as needed. Specifically, the weight ratio of the raw material mixture to the liquid medium can be 1:(10~100). The conditions for the wet ball milling can include: a rotation speed of 100~3000 r / min, a time of 1~24 h, and a temperature of 25~100℃.
[0023] The drying conditions may include: a temperature of 30~100℃ and a time of 1~10h.
[0024] The raw materials can be uniformly mixed through step S1. The ball milling process can grind the raw material particles into finer particles, improve the reactivity, provide good initial conditions for the subsequent growth of lithium iron phosphate crystals, and promote rapid sintering in the subsequent Joule thermal flash evaporation process.
[0025] In step S2, the Joule thermal flash evaporation is a process of heating the material instantaneously through the Joule thermal effect to cause it to evaporate rapidly. The Joule thermal flash evaporation process allows for rapid heating, enabling the ball-milled mixture to reach the required high-temperature range in a very short time, thereby achieving rapid sintering of lithium iron phosphate materials, significantly shortening processing time, reducing energy consumption, and improving production efficiency. The conditions for the Joule thermal flash evaporation can be adjusted within a certain range. Specifically, the conditions may include: current of 1~1000A, temperature of 600~1200℃, and time of 10~600s.
[0026] Traditional methods produce lithium iron phosphate particles with a wide size distribution, typically exhibiting a normal distribution, and their size is difficult to control precisely. The lithium iron phosphate material prepared by the Joule thermal flash evaporation process disclosed in this invention exhibits uniform particle size and a narrow particle size distribution. The specific particle size of the lithium iron phosphate material can be adjusted within a certain range; for example, the D10 particle size can be 0.005~8μm, the D50 particle size can be 0.02~10μm, and the D90 particle size can be 0.1~12μm.
[0027] Furthermore, by controlling the conditions of the Joule thermal flash evaporation, precise control of the particle size of the prepared lithium iron phosphate material and multi-stage gradation of particles of different sizes can be achieved. In one specific embodiment, the Joule thermal flash evaporation is carried out in a Joule thermal apparatus, as described in the reference... Figure 1 The Joule heating device has n flash chambers 1 arranged in parallel, and the operating conditions of the n flash chambers 1 can be independently controlled. In this case, the method may further include: dividing the ball-milled mixture into n streams and feeding them into the n flash chambers for Joule heating flash evaporation to obtain n types of lithium iron phosphate materials; wherein the operating conditions of at least two of the n flash chambers are controlled to be different, so that at least two of the n types of lithium iron phosphate materials have different D50 particle size ranges.
[0028] The flash chamber 1 can be a tubular structure made of polytetrafluoroethylene (PTFE) tubing, each with an inlet and an outlet to achieve independent feeding and discharging. Furthermore, each flash chamber 1 can be equipped with an independent power module to provide Joule heating to that flash chamber 1; the Joule heating device can also include a monitoring and control module for real-time monitoring and independent control of the operating conditions of the n flash chambers 1.
[0029] The specific distribution ratio of the ball-milled mixture fed into each flash chamber 1 and the number n of the flash chambers 1 can be set according to actual needs. Preferably, n can be 8 to 10. That is, by controlling the Joule heat flash evaporation conditions, up to 8 to 10 kinds of lithium iron phosphate materials with different particle size ranges can be prepared simultaneously. Each lithium iron phosphate material has the characteristics of uniform particle size and narrow particle size distribution. Mixing these lithium iron phosphate materials can form a variety of particle size distribution schemes, thereby achieving both high compaction density and excellent electrical performance in the preparation of battery electrodes, promoting the improvement of battery product quality.
[0030] For example, when the Joule heating device has eight flash chambers arranged in parallel, namely the first flash chamber, the second flash chamber, ... the eighth flash chamber, the ball-milled mixture is divided into eight streams and fed into the eight flash chambers respectively for Joule heating flash evaporation. By controlling the operating conditions of at least two of the eight flash chambers to be different, two to eight types of lithium iron phosphate materials with different particle size ranges can be obtained. In the optimal case, the operating conditions of each flash chamber and the corresponding D10, D50, and D90 particle size ranges of the obtained lithium iron phosphate materials can be shown in Table 1 below, and the particle size distribution width (Span) of each lithium iron phosphate material can be 0.5~1.8.
[0031] Table 1
[0032] For example, when the Joule heating device has nine flash chambers arranged in parallel, namely the first to the ninth flash chambers, the operating conditions of the ninth flash chamber and the corresponding D10, D50, and D90 particle size ranges of the resulting lithium iron phosphate material can be shown in Table 2 below. The operating conditions of the first to the eighth flash chambers and the corresponding D10, D50, and D90 particle size ranges of the resulting lithium iron phosphate material can be referred to Table 1 above. The particle size distribution width (Span) of each lithium iron phosphate material can be 0.5 to 1.8.
[0033] Table 2
[0034] For example, when the Joule heating device has 10 flash chambers arranged in parallel, namely the first flash chamber to the tenth flash chamber, the operating conditions of the tenth flash chamber and the corresponding D50 particle size range of the resulting lithium iron phosphate material can be shown in Table 3 below. The operating conditions of the first flash chamber to the eighth flash chamber and the corresponding D10, D50, and D90 particle size ranges of the resulting lithium iron phosphate material can be referred to Table 1 above. The operating conditions of the ninth flash chamber and the corresponding D10, D50, and D90 particle size ranges of the resulting lithium iron phosphate material can be referred to Table 2 above. The particle size distribution width (Span) of each lithium iron phosphate material can be 0.5~1.8.
[0035] Table 3
[0036] Furthermore, the method may also include a step of pulverizing the lithium iron phosphate material, wherein the pulverization may be performed using an air jet mill.
[0037] The lithium iron phosphate material preparation method disclosed herein overcomes many shortcomings of traditional methods, such as slow heating rate, long holding time, and cumbersome process during high-temperature sintering. It eliminates the need for complex equipment and processes, significantly reducing energy consumption and improving production efficiency, making it suitable for large-scale production. The lithium iron phosphate material prepared using this method exhibits uniform particle size and narrow particle size distribution, particularly achieving multi-level particle size distribution. When used in the preparation of lithium-ion battery electrodes, it helps to increase the proportion of small-sized particles while meeting high compaction density requirements. Furthermore, it demonstrates excellent kinetic and low-temperature performance, adapting to a wide range of battery operating temperatures, thus improving battery product performance and showing promising application prospects.
[0038] In a second aspect, this disclosure provides a lithium iron phosphate material prepared by the method described in the first aspect of this disclosure. The lithium iron phosphate material has the same beneficial effects as described above, and will not be repeated here.
[0039] In a third aspect, this disclosure provides a lithium-ion battery comprising the lithium iron phosphate material described in the second aspect of this disclosure.
[0040] This disclosure does not impose any special limitations on the specific structure, packaging form, and manufacturing method of the lithium-ion battery. For example, the lithium-ion battery may include a positive electrode, a negative electrode, an electrolyte, and a separator. The positive electrode may include a positive current collector and a positive electrode material, wherein the positive electrode material is the lithium iron phosphate material described in the second aspect of this disclosure. The negative electrode may include a negative current collector and a negative electrode material (such as graphite). The electrolyte may be a carbonate-based electrolyte, and the separator may be a polyolefin separator. The packaging form of the lithium-ion battery may be a pouch battery, a square aluminum-cased battery, a blade aluminum-cased battery, etc. The lithium-ion battery has the same beneficial effects as described above, and will not be repeated here.
[0041] The present disclosure is further described in detail below through examples. All raw materials used in the examples are commercially available.
[0042] In this embodiment, the D10, D50, and D90 particle sizes of the lithium iron phosphate material were tested using a Malvern laser particle size analyzer. The particle size distribution width was calculated using the following formula: Particle size distribution width = (D90 - D10) / D50 Example 1 (1) Ferrous sulfate, lithium hydroxide and phosphoric acid are mixed in a molar ratio of 1:1.8:1.8, and glucose and dopant titanium dioxide are added. The weight ratio of ferrous sulfate, glucose and titanium dioxide is 100:0.4:0.08 to obtain the raw material mixture.
[0043] The above raw material mixture was mixed with deionized water at a weight ratio of 1:30 and then wet ball-milled at a speed of 1000 rpm for 6 hours and a temperature of 65°C. The mixture was then centrifuged and dried at 45°C for 1 hour to obtain the ball-milled mixture.
[0044] (2) Adopting such Figure 1 The Joule heating device shown includes eight flash chambers arranged in parallel. The mixture after ball milling is divided into eight streams and fed into the eight flash chambers respectively. Joule heating flash evaporation is carried out according to the operating conditions in Table 4 below to obtain lithium iron phosphate material.
[0045] Table 4
[0046] (3) The above-mentioned lithium iron phosphate material is pulverized using an air jet mill. The pulverized material is conveyed to the classification zone by the rising airflow, where fine powder that meets the particle size requirements is screened out by the horizontally arranged classification channels. Coarse powder that does not meet the particle size requirements is returned to the pulverizing zone for further pulverization. The qualified fine powder is collected by the airflow into the high-efficiency cyclone separator and classified according to particle size. As needed, particles that are too large are reclassified.
[0047] Example 2 (1) Ferrous ammonium sulfate, lithium carbonate and ammonium dihydrogen phosphate are mixed in a molar ratio of 1:1.9:1.9, and glucose and magnesium carbonate are added. The weight ratio of ferrous ammonium sulfate, glucose and magnesium carbonate is 100:0.5:0.09 to obtain the raw material mixture.
[0048] The above raw material mixture was mixed with deionized water at a weight ratio of 1:60 and then wet ball-milled at a speed of 1000 r / min for 6 h at a temperature of 65 °C. The mixture was then centrifuged and dried at 45 °C for 1 h to obtain the ball-milled mixture.
[0049] (2) Adopting such Figure 1 The Joule heating device shown includes 10 flash chambers arranged in parallel. The ball-milled mixture is divided into 10 streams and fed into the 10 flash chambers respectively. Joule heating flash evaporation is carried out according to the operating conditions in Table 5 below to obtain lithium iron phosphate material.
[0050] Table 5
[0051] (3) The above-mentioned lithium iron phosphate material is pulverized using an air jet mill. The pulverized material is conveyed to the classification zone by the rising airflow, where fine powder that meets the particle size requirements is screened out by the horizontally arranged classification channels. Coarse powder that does not meet the particle size requirements is returned to the pulverizing zone for further pulverization. The qualified fine powder is collected by the airflow into the high-efficiency cyclone separator and classified according to particle size. As needed, particles that are too large are reclassified.
[0052] Example 3 The lithium iron phosphate material was prepared according to the method of Example 1, except that in step (1), the molar ratio of ferrous sulfate, lithium hydroxide and phosphate was 1:1:1, and the weight ratio of ferrous sulfate, glucose and titanium dioxide was 100:2:0.15.
[0053] Example 4 The lithium iron phosphate material was prepared according to the method of Example 1, except that in step (1), the molar ratio of ferrous sulfate, lithium hydroxide and phosphate was 1:3.5:3.5, and the weight ratio of ferrous sulfate, glucose and titanium dioxide was 100:3:0.28.
[0054] Example 5 The lithium iron phosphate material was prepared according to the method of Example 1, except that in step (2), only the three flash chambers in the Joule heating equipment were used, and the ball-milled mixture was divided into three streams and fed into the three flash chambers respectively. Joule heating flash evaporation was carried out according to the operating conditions in Table 6 below to obtain the lithium iron phosphate material.
[0055] Table 6
[0056] Comparative Example 1 Lithium iron phosphate material was prepared using a traditional solid-state method, specifically as follows: Weighing and feeding: Iron phosphate, lithium carbonate, and glucose (molar ratio 1:2.8:2.8) were mixed evenly in water and stirred for 20 hours. The mixture was then ground in an ultrafine mill for 2 hours. Subsequently, the ultrafine powder was sand-milled for 1-2 hours to obtain secondary powder. The secondary powder and granulating agent were placed in a spray dryer for drying for ≤10 hours. The dried secondary powder was then packed into bowls and spray-dried again under vacuum. The packed secondary powder was then transferred to a pusher kiln for sintering, with the high-temperature zone temperature ranging from 752 to 766°C for a total sintering time of 24 hours. The sintered lithium iron phosphate was then pulverized in an air jet mill to obtain lithium iron phosphate material with a D10 particle size of 0.25 μm, a D50 particle size of 1.1 μm, a D90 particle size of 2.5 μm, and a particle size distribution width of 2.05.
[0057] Test case The lithium iron phosphate materials used in the examples and comparative examples were used to fabricate pouch batteries and their performance was tested. The results are listed in Table 7.
[0058] The preparation method of the soft pack battery is as follows: lithium iron phosphate material and graphite negative electrode material are mixed and processed through slurry preparation, coating, rolling, cutting, stacking, micro short circuit testing, spot welding of tabs, aluminum plastic sealing, liquid injection, vacuum standing, formation, aging, and final sealing to finally prepare a soft pack battery with a capacity of 2Ah. The test method for powder compaction density is as follows: A dry compaction test method is used. Lithium iron phosphate powder is pressed into round discs (30 kN) using a tablet press. The density is determined according to ρ = m / hπr. 2 The formula calculates the corresponding compaction density.
[0059] The test method for the energy retention rate of pouch batteries at -20℃ is as follows: After fully charging the pouch battery at 0.33C, let it stand at -20℃ for 4 hours, and then discharge it at 1C. The energy of the discharge at 25℃ and 1C is compared.
[0060] The test method for rate performance is as follows: after fully charging the soft-pack battery at 0.33C, discharge it at a 5C rate and compare the discharge capacity with that at 0.33C.
[0061] Table 7
[0062] As shown in Table 7, using the lithium iron phosphate material from the embodiments as the cathode material can improve the compaction density, low-temperature energy retention rate of the pouch cell, and 5C rate energy retention rate, demonstrating excellent kinetic and low-temperature performance.
[0063] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.
[0064] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.
[0065] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.
Claims
1. A method for producing a lithium iron phosphate material, characterized by, The method comprises: mixing raw material mixture containing lithium source, iron source, phosphorus source, carbon source and dopant, wet ball milling and drying to obtain the ball-milled mixture; Joule heat flash evaporation is carried out on the ball-milled mixture to obtain lithium iron phosphate material.
2. The method of claim 1, wherein, The molar ratio of the iron source, the lithium source and the phosphorus source is 1:(1-4):(1-4); The weight ratio of the iron source, the carbon source and the dopant is 100:(0.001-10):(0.0001-0.4).
3. The method of claim 1, wherein, The lithium source is at least one selected from lithium oxide, lithium hydroxide, lithium phosphate, lithium carbonate, lithium nitrate, lithium dihydrogen phosphate, lithium formate and lithium acetate.
4. The method of claim 1, wherein, The iron source is at least one selected from iron, iron phosphate, ferrous sulfate, diiron trioxide, ferrous oxide, magnetite, ferrous ammonium sulfate, ferrous sulfate and ferrous phosphate; and / or, The phosphorus source is at least one selected from diaphosphorus pentoxide, phosphoric acid, ammonium dihydrogen phosphate, lithium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium ferrophosphate and ammonium hydrogen phosphate.
5. The method of claim 1, wherein, The carbon source is at least one selected from glucose, sucrose, maltose, polyethylene glycol, polyvinyl alcohol, citric acid, acetylene black, carbon nanotube and carbon nanofiber; and / or, The dopant is at least one selected from the elemental and compound of titanium, manganese, cobalt, vanadium, nickel, aluminum, magnesium, calcium, zinc, silver and copper.
6. The method of claim 1, wherein, The conditions of the wet ball milling include: rotation speed of 100-3000 r / min, time of 1-24 h and temperature of 25-100℃; and / or, The conditions of the drying include: temperature of 30-100℃ and time of 1-10 h.
7. The method of claim 1, wherein, The conditions of the Joule heat flash evaporation include: current of 1-1000 A, temperature of 600-1200℃ and time of 10-600 s; and / or, The D10 particle size of the lithium iron phosphate material is 0.005-8 μm, the D50 particle size is 0.02-10 μm and the D90 particle size is 0.1-12 μm.
8. The method of claim 1, wherein, The Joule heat flash evaporation is carried out in a Joule heat device having n flash cavities arranged in parallel, and the operating conditions of the n flash cavities can be independently controlled. The method further comprises: dividing the ball-milled mixture into n streams and feeding them into the n flash cavities respectively for Joule heat flash evaporation to obtain n kinds of lithium iron phosphate materials; wherein, the operating conditions of at least two of the n flash cavities are controlled to be different, so that the D50 particle size ranges of at least two of the n kinds of lithium iron phosphate materials are different. Preferably, n is 8-10.
9. The lithium iron phosphate material prepared by the method of any one of claims 1-8.
10. A lithium-ion battery, characterized by, The lithium iron phosphate material of claim 9.