Preparation of positive electrode material of lithium ion cell namely lithium iron phosphate

A technology for lithium ferrous phosphate and lithium-ion batteries, which is applied in electrode manufacturing, battery electrodes, chemical instruments and methods, etc. It can solve the problems of poor product reproducibility and consistency, uneven mixing, and messy particle sizes of products. Achieve the effects of easy process control, low cost, and uniform distribution of precursors

Inactive Publication Date: 2008-10-22
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the high-temperature solid-phase method has a simple process, due to the uneven mixing, the particle size of the product is disordered, the product reproducibility and consistency are poor, and it is difficult to obtain a pure-phase sample, and the iron source used is easily decomposed and expensive. Iron compounds, these are the unfavorable factors in practical application

Method used

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  • Preparation of positive electrode material of lithium ion cell namely lithium iron phosphate
  • Preparation of positive electrode material of lithium ion cell namely lithium iron phosphate
  • Preparation of positive electrode material of lithium ion cell namely lithium iron phosphate

Examples

Experimental program
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Effect test

Embodiment 1

[0030] Fe 3+ Salt and H 3 PO 4 , and then add deionized water to make 0.1mol·L -1 mixed solution, and then the concentrated NH 3 ·H 2 O made into 0.3mol·L -1 solution, the ammonia solution was added to Fe under magnetic stirring 3+ and H 3 PO 4 In the mixed solution, the pH is controlled to be 2.1, and the precipitate is dried at 110°C for 3 hours to obtain FePO 4 ·xH 2 O powder. Weigh 0.1mol FePO 4 ·xH 2 O, 0.11mol lithium-containing molten salt LiOH·H 2 O and 0.061mol glucose ball milled for 5h and mixed evenly. The powder was placed in a muffle furnace at 480°C for 5 hours under an argon atmosphere, then heated to 600°C at a rate of 2°C / min, calcined for 8 hours, and cooled naturally to obtain the prepared lithium iron phosphate. Its crystal structure is shown in figure 1 . Depend on figure 1 It can be seen that the lithium iron phosphate prepared by the above method is a pure phase, and the crystallinity of the material is good.

[0031]Fully mix the prep...

Embodiment 2

[0033] Fe 3+ Salt and H 3 PO 4 , and then add deionized water to make 0.1mol·L -1 mixed solution, and then the concentrated NH 3 ·H 2 O made into 0.3mol·L -1 solution, the ammonia solution was added to Fe under magnetic stirring 3+ and H 3 PO 4 In the mixed solution, the pH is controlled at 1.9, and the precipitate is dried at 110°C for 3 hours to obtain FePO 4 ·xH 2 O powder. Weigh 0.1mol FePO 4 ·xH 2 O, 0.13mol lithium-containing mixed molten salt (LiOH·H 2 O+LiNO 3 , the former 0.1mol, the latter 0.03mol) and 0.061mol glucose ball milled for 5h and mixed evenly. The powder was placed in a muffle furnace at 300°C for 5 hours under an argon atmosphere, then heated to 600°C at a rate of 2°C / min, calcined for 8 hours, and cooled naturally to obtain the prepared lithium iron phosphate. Other tests are the same as above.

Embodiment 3

[0035] Fe 3+ Salt and H 3 PO 4 , and then add deionized water to make 0.1mol·L -1 mixed solution, and then the concentrated NH 3 ·H 2 O made into 0.3mol·L -1 solution, the ammonia solution was added to Fe under magnetic stirring 3+ and H 3 PO 4 In the mixed solution, the pH is controlled to 2.2, and the precipitate is dried at 110°C for 3 hours to obtain FePO 4 ·xH 2 O powder. Weigh 0.1mol FePO 4 ·xH 2 O, 0.13mol lithium-containing mixed molten salt (LiOH·H 2 O+LiNO 3 ,) and 0.03mol sucrose ball milled for 5h and mixed evenly. The powder was placed in a muffle furnace at 300°C for 5 hours under an argon atmosphere, then heated to 650°C at a rate of 2°C / min, calcined for 8 hours, and cooled naturally to obtain the prepared lithium iron phosphate. Other tests are the same as above.

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Abstract

The invention discloses a method for making a LiFePO4 positive pole material of a lithium ion battery, which comprises preparing uniformly distributed FePO4 precursor powder with controllable shape and granularity by a chemical precipitation method using ferric compounds and phosphorous acid as raw materials; mixing the molten salt of lithium source, Carbon source and FePO4 precursor together by a molten salt method to obtain LiFePO4 by baking. The method making LiFePO4 by chemical precipitation and molten salt allows materials to be made into target materials with excellent crystal structure at a relatively lower temperature in a short period as the precursor is uniformly distributed and the molten salt can serve as a flux. The materials made by the method have excellent electrochemical properties.

Description

technical field [0001] The invention relates to the field of material chemistry and the technical field of high-energy battery materials, in particular to a lithium-ion battery cathode material lithium iron phosphate (LiFePO 4 ) preparation method. Background technique [0002] Lithium-ion batteries have the advantages of small size, light weight, large specific capacity, long cycle life, small self-discharge, and no memory effect. At present, it has been widely used in portable mobile tools, digital products, artificial satellites, aerospace and other fields, and has very broad prospects in the fields of electric bicycles and automobiles. The cathode material is the most critical part of lithium-ion batteries. The mainstream cathode material on the market is lithium cobalt oxygen, but cobalt is highly toxic, cobalt resources are seriously scarce, and the price is expensive. Its overcharge and discharge resistance is not good, and its safety performance is not good. Well, ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/58H01M4/48H01M4/04C01B25/45
CPCY02E60/10
Inventor 黄可龙刘素琴王海燕方东龚本利
Owner CENT SOUTH UNIV
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