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Wet chemistry method for preparing lithium iron phosphate

A wet chemical method, lithium iron phosphate technology, applied in chemical instruments and methods, inorganic chemistry, phosphorus compounds, etc., can solve the problem of increasing cost and complexity of production process, increasing preparation cost and complexity of process, and inability to obtain nanoparticles, etc. problems, to achieve the effect of low price, easy operation and control, and uniform distribution

Inactive Publication Date: 2003-07-23
郑绵平
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In this type of synthetic method, due to the use of expensive H 2 o 2 , LiI and ascorbic acid and other reagents, thereby increasing the cost of the product and the complexity of the production process
[0008] In short, in the existing synthetic methods, the high-temperature solid-phase method either cannot obtain nanoparticles, or needs to use expensive acetate and carbon gel; although the hydrothermal method can control the particle size, it is not easy to realize industrialization; redox method requires the use of H 2 o 2 , LiI and ascorbic acid and other reagents increase the preparation cost of the material and the complexity of the process

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] Example 1 After the lithium chloride solution of 0.5mol / L and the ferrous sulfate solution of 0.5mol / L and 10% carbon black are fully mixed, then add the ammonium phosphate solution of 0.5mol / L of 1.0 times of the theoretical amount, at 25 °C for 6 hours, filtered, washed and dried to obtain the precursor. The precursor was heated to a specified temperature at a rate of 1°C / min in a nitrogen atmosphere and kept for a certain period of time, and then cooled to room temperature with the furnace. The firing conditions used in the experiment are listed in Table 1. The obtained products were analyzed by X-ray diffraction, showing that they were all olivine-type LiFePO 4 , The crystal structure is complete, and the particle size of the product is between 400nm and 600nm. The composition of the product was determined by plasma emission spectrometry (ICP), and the results are shown in Table 1. The resulting product is assembled into an experimental battery, and its charge-di...

Embodiment 2

[0022] Example 2 After fully mixing 0.5mol / L lithium chloride solution, 0.5mol / L ferrous sulfate solution and 10% carbon black (A5), add 0.5mol / L ammonium phosphate solution which is 1.0 times the theoretical amount , carry out precipitation reaction under different conditions, filter, wash and dry to obtain the precursor. The precursor was heated to 600 °C for 8 hours at a heating rate of 1 °C / min in a nitrogen atmosphere, and cooled to room temperature at a cooling rate of 1 °C / min. The conditions of the precipitation reaction are shown in Table 2. The obtained products were analyzed by X-ray diffraction, showing that they were all olivine-type LiFePO 4 , The crystal structure is complete, and the particle size of the product is between 400nm and 600nm. The composition of the product was determined by plasma emission spectrometry (ICP), and the results are shown in Table 2. The resulting product is assembled into an experimental battery, and its charge-discharge specific ...

Embodiment 3

[0025] Example 3 After fully mixing 0.5 mol / L phosphoric acid solution and iron salt solution with 10% carbon black, then adding lithium salt solutions of different types and concentrations, reacting at 60°C for 3 hours, filtering, washing and drying to obtain Precursor. The precursor was heated to 600 °C for 8 hours at a heating rate of 10 °C / min in a nitrogen atmosphere, and then cooled to room temperature at a cooling rate of 10 °C / min. The types and concentrations of lithium salts and iron salts used in the experiment are shown in Table 3. The obtained products were analyzed by X-ray diffraction, showing that they were all olivine-type LiFePO 4 , The crystal structure is complete, and the particle size of the product is between 300nm and 500nm. The composition of the product was determined by plasma emission spectrometry (ICP), and the results are shown in Table 3. The resulting product is assembled into an experimental battery, and its charge-discharge specific capacit...

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Abstract

A wet chemical process for preparing iron lithium phosphate includes mixing the solution or suspensions of Li source compound, Fe source compound, P source compound, doping element compound or electric conducting agent, and precipitant, reaction at 5-120 deg.C for 0.5-24 hr while stirring, filtering, washing, baking to obtain nano precursor, quickly heating to 500-800 deg.C in non-air or non-oxidizing atmosphere, calcining for 5-48 hr, and cooling. Its advantages are easy control, high uniformity and electric conductivity.

Description

technical field [0001] The invention belongs to a preparation method of a positive electrode material of a lithium ion battery, in particular to a method for preparing a positive electrode material lithium iron phosphate (LiFePO 4 ) wet chemical method. Background technique [0002] In the study of lithium-ion batteries, with α-NaFeO 2 Materials with type structures have always been a research hotspot. These materials include LiCoO 2 , LiNiO 2 , LiMnO 2 and LiVO 2 Wait. LiCoO 2 It is the positive electrode material currently used in commercial lithium-ion batteries. It has a high theoretical specific capacity (274mAh / g) and good cycle performance, but its actual specific capacity is only about 140mAh / g. When charging, the amount of lithium released When it is greater than 55%, the structure of the material will be destroyed and its cycle performance will be reduced. In addition, the abundance of cobalt in nature is low and the price is relatively expensive; for LiNiO...

Claims

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Application Information

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IPC IPC(8): C01B25/45H01M4/58
CPCH01M4/1397H01M4/5825H01M4/0471Y02E60/122H01M10/052H01M4/136Y02E60/10
Inventor 郑绵平文衍宣
Owner 郑绵平
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