A precursor with iron-rich surface and manganese-rich core and method for preparing carbon-coated lithium manganese iron phosphate material using the precursor as raw material

A technology of lithium manganese iron phosphate and carbon coating, which is applied in the direction of electrical components, battery electrodes, circuits, etc., can solve the problems of underutilized precursor raw material preparation process, difficulty in controlling reaction conditions, product purity, and high quality control requirements for raw materials. , to achieve the effect of easy regulation of material composition distribution, improvement of electrical conductivity and electrochemical performance, and good practical value

Active Publication Date: 2017-08-04
GENERAL RESEARCH INSTITUTE FOR NONFERROUS METALS BEIJNG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The main problems of this method are: 1) Repeated powder cleaning and drying treatment must be carried out after each step of synthesis, and the process is cumbersome; Very high, and it is difficult to control the reaction conditions and the purity of the resulting product in large-scale production
However, they also adopted the process route of first synthesizing the core material and then coating the shell material, which requires multi-step synthesis and heat treatment processes, which is more complicated and time-consuming
[0008] It can be seen that the methods introduced in the previous work on the preparation of surface-coated lithium iron phosphate cathode materials are very cumbersome and difficult to control, and do not make full use of different types of precursor raw materials to simplify the preparation process

Method used

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  • A precursor with iron-rich surface and manganese-rich core and method for preparing carbon-coated lithium manganese iron phosphate material using the precursor as raw material
  • A precursor with iron-rich surface and manganese-rich core and method for preparing carbon-coated lithium manganese iron phosphate material using the precursor as raw material
  • A precursor with iron-rich surface and manganese-rich core and method for preparing carbon-coated lithium manganese iron phosphate material using the precursor as raw material

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Effect test

Embodiment 1

[0040] Carbon-coated lithium manganese iron phosphate materials were prepared based on precursors rich in iron on the surface and rich in manganese in the core. In this method, the precursor is not separated after preparation, and other raw materials are directly added to it for reaction to prepare a carbon-coated lithium manganese iron phosphate material. Among them, the chemical formula of lithium manganese iron phosphate is Li a mn x Fe y m 1-x-y P b o 4 , where a=1, x=0.5, y=0.5, b=1.00.

[0041] First prepare the surface iron-rich precursor, according to the stoichiometric ratio of lithium manganese phosphate, weigh lithium acetate, manganese phosphate (trivalent) hydrate (D 50 =200nm), ferric nitrate, and ammonium dihydrogen phosphate as raw materials, dispersed in deionized water, and adding 10 mol% sucrose relative to (Mn+Fe+M) moles as a carbon source, to prepare 1mol of lithium manganese iron phosphate precursor . Stir the slurry at 200r / min for 0.5h, and the...

Embodiment 2

[0045] Carbon-coated lithium manganese iron phosphate materials were prepared based on precursors rich in iron on the surface and rich in manganese in the core. In this method, the precursor is obtained first, and then mixed with other soluble raw materials to prepare carbon-coated lithium manganese iron phosphate material. Among them, the chemical formula of lithium manganese iron phosphate is Li a mn x Fe y m 1-x-y P b o 4 , where a=1.06, x=0.75, y=0.23, b=1.01, M=Zn.

[0046] First prepare the surface iron-rich precursor, according to the stoichiometric ratio, weigh manganese carbonate (D 50 =150nm), ferric citrate, zinc nitrate raw materials, the surface iron-rich precursor of preparing 1mol of lithium manganese iron phosphate. Put several raw materials into deionized water, stir for 0.5h, then dropwise add 0.1mol / L ammonia water and keep stirring until the soluble iron source and zinc source are completely converted into the precipitate coating layer on the surface...

Embodiment 3

[0051] Carbon-coated lithium manganese iron phosphate materials were prepared based on precursors rich in iron on the surface and rich in manganese in the core. In this method, the precursor is not separated after preparation, and other raw materials are directly added to it for reaction to prepare a carbon-coated lithium manganese iron phosphate material. Among them, the chemical formula of lithium manganese iron phosphate is Li a mn x Fe y m 1-x-y P b o 4 , where a=0.97, x=0.35, y=0.63, b=0.98, M=Mg.

[0052] First prepare the surface iron-rich precursor, according to the stoichiometric ratio, weigh ammonium manganese phosphate (D 50 =100nm), ferric citrate, and magnesium acetate as raw materials to prepare a surface iron-rich precursor of 1 mol of lithium manganese iron phosphate. Put several raw materials into deionized water, stir for 0.7h, then dropwise add 0.2mol / L ammonia water and keep stirring until the soluble iron source and magnesium source are completely c...

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Abstract

The invention discloses a precursor rich in iron on the surface and rich in manganese on the core and a method for preparing a carbon-coated manganese-iron-lithium phosphate material by taking the precursor as a raw material. The primary particle size of the precursor is 15-500 nanometers; the specific surface area is 5-100 m<2> / g; iron elements are enriched 0-5 nanometers away from particle surfaces; the content of manganese within a depth range is less than 0.01 wt%; and manganese elements are intensively distributed on the cores of material particles. The method for preparing the carbon-coated manganese-iron-lithium phosphate material based on the precursor comprises the following steps: synthesizing the precursor according to the chemical formula of manganese-iron-lithium phosphate, putting the precursor, a Li-containing compound, a P-containing compound, a metal M-containing compound and a carbon source organic matter raw material into a dispersion medium, and mixing the materials to obtain a slurry; and drying and calcining the slurry to obtain the carbon-coated manganese-iron-lithium phosphate material. The precursor which is rich in iron on the surface is taken as the raw material for synthesizing the manganese-iron-lithium phosphate material, and the carbon deposition state on the surfaces of electrode material particles in a calcining process is improved, so that the electrical conductivity and electrochemical performance are improved.

Description

technical field [0001] The invention relates to a precursor with iron-rich surface and manganese-rich core and a method for preparing a carbon-coated lithium manganese iron phosphate material by using the precursor as a raw material, belonging to the technical field of chemical batteries. Background technique [0002] With the continuous development of human society, the energy consumption in daily life and industrial production continues to increase. In recent years, the portability and wirelessization of 3C electronic products, various electric tools and other power appliances have developed rapidly. The advancement of these technologies has also brought about higher consumption of energy storage and secondary batteries that can be repeatedly charged and discharged. and performance requirements. In addition, in order to protect the earth's environment and ensure energy security, in recent years, the industry of hybrid electric vehicles and pure electric vehicles using sec...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/505H01M4/525
CPCY02E60/10
Inventor 刘冠伟张向军刘丙学赵挺杨容王琦樊腾飞江丹平
Owner GENERAL RESEARCH INSTITUTE FOR NONFERROUS METALS BEIJNG
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