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A kind of preparation method of lithium iron silicate

A technology of lithium iron silicate and metatitanic acid, applied in chemical instruments and methods, silicon compounds, structural parts, etc., can solve the problems of short cycle life, low conductivity, weak connection force, etc., and achieve improved electrical performance, The effect of small specific surface area and high compaction density

Active Publication Date: 2020-11-10
郑忆依
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Lithium iron silicate has the advantages of no pollution, low price, and high safety, and has become a promising material, but its electrical conductivity is low, and its volume changes during charging and discharging. At the same time, it is different from the other two tetrahedral or octahedral faces or ridge-connected models, this high-capacity material is a stack of tetrahedral vertices connected
There is a weak connection force between the tetrahedrons, and the structure is easy to phase change or even break during the charge and discharge process, resulting in a short cycle life
At the same time, its low electronic conductivity and lithium-ion diffusion coefficient limit its application in commercial lithium-ion batteries.

Method used

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] A kind of preparation method of lithium iron silicate, it is the following steps:

[0030] (1) Dissolve the by-product of titanium dioxide in water, then add the mixture of filter aid and activated carbon, stir for 20 minutes, then filter, add nanometer metatitanic acid to the filtrate, then add polyethylene glycol, stir and disperse for 35 minutes, then add urea, and then Raise the temperature to 102°C, and at the same time pass through air to react for 4.3 hours, and the obtained solid particles are washed to obtain iron-coated titanium precipitated particles;

[0031] (2) Add hydrogen fluoride solution to the iron-coated titanium precipitated particles obtained in step (1), react at a temperature of 73°C for 42 minutes, then add lithium hydroxide and silicic acid, continue to stir and react at 73°C for 18 minutes, and then add sucrose, After mixing and stirring to dissolve, spray drying is carried out to obtain a dry material;

[0032] (3) Put the dry material obtai...

Embodiment 2

[0041] A kind of preparation method of lithium iron silicate, it is the following steps:

[0042] (1) Dissolve the titanium dioxide by-product in water, then add the mixture of filter aid and activated carbon, stir for 25 minutes, then filter, add nano-metitanic acid to the filtrate, then add polyethylene glycol, stir and disperse for 33 minutes, then add urea, and then Raise the temperature to 102°C, and at the same time pass through air to react for 4.6 hours, and the obtained solid particles are washed to obtain iron-coated titanium precipitated particles;

[0043] (2) Add hydrogen fluoride solution to the iron-coated titanium precipitate particles obtained in step (1), react at a temperature of 71°C for 42min, then add lithium hydroxide and silicic acid, continue to stir and react at 71°C for 19min, then add sucrose, After mixing and stirring to dissolve, spray drying is carried out to obtain a dry material;

[0044] (3) Put the dried material obtained in step (2) into a ...

Embodiment 3

[0053] A kind of preparation method of lithium iron silicate, it is the following steps:

[0054] (1) Dissolve the by-product of titanium dioxide in water, then add the mixture of filter aid and activated carbon, stir for 28min, then filter, add nanometer metatitanic acid to the filtrate, then add polyethylene glycol, stir and disperse for 37min, then add urea, then Raise the temperature to 101°C, and at the same time pass through the air to react for 4.6 hours, and the obtained solid particles are washed to obtain iron-coated titanium precipitated particles;

[0055] (2) Add hydrogen fluoride solution to the iron-coated titanium precipitate particles obtained in step (1), react at a temperature of 72°C for 41min, then add lithium hydroxide and silicic acid, continue to stir and react at 69°C for 23min, then add sucrose, After mixing and stirring to dissolve, spray drying is carried out to obtain a dry material;

[0056] (3) Put the dried material obtained in step (2) into a ...

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Abstract

The invention discloses a preparation method of lithium iron silicate. The preparation method comprises the following steps: adding water into a titanium dioxide byproduct for dissolving, filtering, adding nano-metatitanic acid into filtrate, stirring for dispersion, adding urea, heating until introduced air generates reaction so as to obtain iron-coated titanium precipitate particles, adding a hydrogen fluoride solution, lithium hydroxide and silicic acid, stirring for reaction, adding sucrose, and carrying out spray drying, so as to obtain a dried material; putting the obtained dried material into a sintering furnace, calcining by virtue of a heating stage, a thermal insulation stage and a cooling stage, cooling to be below 50 DEG C, and discharging; and crushing the discharged materialby virtue of airflow, sieving for removing ion, and carrying out vacuum packaging, so as to obtain lithium iron silicate. An iron-coated titanium structure with lithium as a core and iron as a shell is formed and is coated with carbon, so that the electric performance of lithium iron silicate is greatly improved; and lithium iron silicate prepared by virtue of the process is small in specific surface area and high in compaction density, the process is low in cost and short in process flow, and the preparation method is simple.

Description

technical field [0001] The invention relates to a preparation method of lithium iron silicate, which belongs to the technical field of lithium battery cathode materials. Background technique [0002] At present, commercial lithium-ion battery cathode materials mainly include inorganic compounds with layered structure, spinel structure and polyanion structure. According to the classification of chemical bonds and packing models, these structures can be divided into octahedron (lithium cobalt oxide and layered ternary materials), tetrahedron (silicate material) and tetrahedral and octahedral hybrid (lithium iron phosphate and lithium manganese oxide materials) structure. Compared with other materials, the tetrahedral structure material is a kind of potential high-capacity material, such as Li 2 FeSiO 4 Theoretically, the cathode material can achieve two Li+ intercalation, and the specific capacity is as high as 332mAh / g. [0003] Lithium iron silicate has the advantages of...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/20H01M4/58H01M10/0525
CPCC01B33/20H01M4/5825H01M10/0525Y02E60/10
Inventor 郑忆依
Owner 郑忆依