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Process for preparing high density spherical lithium ferric phosphate

A lithium iron phosphate, high-density technology, applied in chemical instruments and methods, phosphorus compounds, inorganic chemistry, etc., can solve the problems of low tap density of lithium iron phosphate, reduce material bulk density, reduce bulk density, etc., and achieve average residence time The effect of shortened time, wide source of raw materials and simple process

Inactive Publication Date: 2006-08-23
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] However, the problem that the tap density of lithium iron phosphate is too low has been ignored and avoided by people.
At present, the lithium iron phosphate cathode materials reported at home and abroad are all composed of irregular flake or granular particles. Because these particles support each other, the gaps between the particles are too large, which reduces the packing density, and due to the irregular shape of the particles The appearance prevents the carbon from being tightly attached to the surface of the particles, and also greatly reduces the packing density of the material.

Method used

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Examples

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preparation example Construction

[0025] The invention provides a method for preparing a high-density spherical lithium iron phosphate used as a cathode material of a lithium ion battery. The method for preparing high-density spherical lithium iron phosphate comprises the following steps:

[0026] (1) Ferrous sulfate, phosphorus source, and reducing agent are mixed and ground, wherein the molar ratio of iron to phosphorus is (0.5-1): 1, and the amount of reducing agent added is reducing agent: deionized water=(0.001-0.05): 1 (mass ratio).

[0027] (2) above-mentioned ferrous sulfate, diammonium hydrogen phosphate, reducing agent are mixed solid powder, and basic substance powder is respectively continuously input in the reactor with stirring with screw propeller, and the temperature of reaction solution in the control reactor is 20- 80°C, mix ferrous sulfate, phosphorus source, and reducing agent, and the solid powder addition rate corresponds to 0.0025g / min-0.25g / min for 1ml of deionized water; the mass rati...

Embodiment 1

[0036] 700g of ferrous sulfate (FeSO 4 ·7H 2 O), 332g of diammonium phosphate ((NH 4 ) 2 HPO 4 ), the ascorbic acid of 10g was mixed uniformly, and was placed in a ball mill for ball milling for 2 hours; 300g ammonium carbonate was placed in a ball mill for ball milling for 2 hours; ferrous sulfate, diammonium hydrogen phosphate, ascorbic acid were mixed with a screw propeller, and the solid powder was mixed with 10g seven Water ferrous sulfate per minute is added to the reactor equipped with 1 liter of deionized water for reaction; at the same time, ammonium carbonate powder is added with a screw propeller to adjust the addition speed of ammonium carbonate to control the pH of the reaction solution in the reactor The value is 4.5, control the temperature in the reactor to 40°C, continue to stir for 30 minutes after adding the materials, discharge the materials in the reactor, separate the solid and liquid with a centrifuge, and wash the solid product with deionized water a...

Embodiment 2

[0038] 700g ferrous sulfate (FeSO 4 ·7H 2 O), 289g ammonium dihydrogen phosphate (NH 4 h 2 PO 4 )), 3g ascorbic acid were mixed evenly, placed in a ball mill for ball milling for 2 hours, 500g ammonium carbonate was placed in a ball mill for ball milling for 2 hours, ferrous sulfate, ammonium dihydrogen phosphate, ascorbic acid mixed solid powder were mixed with 10g heptahydrate with a screw propeller Add ferrous sulfate per minute into a reactor equipped with 1 liter of deionized water for reaction. At the same time, use a screw propeller to add ammonium carbonate powder to adjust the adding speed of ammonium carbonate to control the pH value of the reaction solution in the reactor. 5.5 shall prevail; control the temperature in the reactor to 40°C, continue stirring for 30 minutes after the addition of the materials, discharge the materials in the reactor, and perform solid-liquid separation with a centrifuge; wash the solid product with deionized water at 60°C to Wash wa...

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Abstract

The present invention is microwave synthesis process of high density spherical lithium ferric phosphate as the positive electrode material of lithium ion cell, and belongs to the field of energy source material preparing technology. Spherical lithium ferric phosphate is prepared through mixing ferrous sulfate and solid phosphorus in the required Fe / P ratio; adding in certain speed into deionized water; adding alkali matter to regulate pH value to form the precursor ammonium ferrous phosphate; drying the precursor, mixing with lithium acetate in the same ratio, adding proper amount of conducting agent, and high temperature treatment at 600-800 deg.c for 3-30 hr in the protecting atmosphere. Thus prepared spherical lithium ferric phosphate has average grain size of 5-10 microns, tap density 2.0-2.3 g / cu cm, and room temperature initial specific discharge capacity of 140-160 mA / g. The process is simple, low in cost, high in yield and suitable for industrial production.

Description

technical field [0001] The invention belongs to the technical field of energy material preparation, and in particular relates to a method for preparing a high-density spherical lithium iron phosphate which is a positive electrode material of a lithium ion battery. Background technique [0002] With the continuous development of social civilization, especially when human society has entered the information age and network age, there is a greater desire for high-quality electric energy. Batteries, especially secondary batteries, will inevitably play a pivotal role in the future society based on electric energy. Since the end of the last century, portable electronic devices such as notebook computers, mobile phones, etc. Smart and light features, so they need a small power supply with small size, large capacity and light weight. In addition, due to frequent use for a long time, customers are more inclined to use relatively economical secondary power sources. [0003] Due to ...

Claims

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Application Information

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IPC IPC(8): C01B25/45H01M4/58
CPCY02E60/12Y02E60/10
Inventor 李维应皆荣姜长印万春荣雷敏唐昌平高剑
Owner TSINGHUA UNIV
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