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Method for preparing carbon-coated LiFePO4 by microwaves and carbon-coated LiFePO4 material

A technology of lithium iron phosphate and carbon coating, applied in chemical instruments and methods, phosphorus compounds, structural parts, etc., can solve problems such as poor conductivity, generation of bubbles, and pollution of lithium iron phosphate cathode materials

Inactive Publication Date: 2010-05-26
SHENZHEN UNIV
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  • Abstract
  • Description
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AI Technical Summary

Problems solved by technology

The carbon encapsulation method adopted in this type of method has the following shortcomings: one is that the conductive carbon black can only form a bridging effect between the lithium iron phosphate particles, and the other is that the organic carbon source will generate bubbles due to self-decomposition during the encapsulation process, which will affect the carbon The uniformity of coating makes it difficult to form a complete conductive network
In addition, microwave absorbers such as activated carbon will also pollute lithium iron phosphate cathode materials due to their poor conductivity.

Method used

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  • Method for preparing carbon-coated LiFePO4 by microwaves and carbon-coated LiFePO4 material
  • Method for preparing carbon-coated LiFePO4 by microwaves and carbon-coated LiFePO4 material
  • Method for preparing carbon-coated LiFePO4 by microwaves and carbon-coated LiFePO4 material

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preparation example Construction

[0024] see figure 1 , showing the microwave preparation process of carbon-coated lithium iron phosphate according to the embodiment of the present invention, including the following steps:

[0025] S01: Obtain lithium source compound, ferrous iron source compound and phosphorus source compound respectively according to the stoichiometric ratio of lithium iron phosphate to be prepared, and add microwave absorber, organic carbon source and liquid dispersant;

[0026] S02: The raw materials obtained by ball milling and drying;

[0027] S03: placing the dried product in a microwave heating reaction chamber, and introducing a protective gas into the reaction chamber;

[0028] S04: Heating to 550-850°C by microwave, feeding carbon source gas, and pyrolyzing the carbon source gas at a temperature of 550-850°C to prepare carbon-coated lithium iron phosphate.

[0029] In step S01, the lithium source compound can be lithium-containing inorganic substances such as lithium carbonate and...

Embodiment 1

[0040] The preparation method of the present embodiment 1 comprises the following specific steps:

[0041] (1) Lithium hydroxide, ferrous oxalate and ammonium hydrogen phosphate were weighed respectively according to the molar ratio of Li: Fe(II): P=0.95: 1: 1, and 5wt% of microwave absorbing agent of electric conduction and heat conduction was added (according to generating ferric phosphate Lithium calculation), sucrose 25wt% (calculated by generating lithium iron phosphate) and acetone,

[0042] (2) high-speed ball milling with agate balls for 10 hours, during ball milling, the mass ratio of each material is: raw material: dispersant: ball=1: 3: 6, forming powder;

[0043] (3) At 60°C, after vacuum drying the powder ground in step (1) for 24 hours, place it in the microwave heating reaction chamber 10;

[0044] (4) After vacuumizing the microwave heating reaction chamber 10, feed nitrogen to an atmospheric pressure;

[0045] (5) Turn on the microwave power of 500W and rais...

Embodiment 2

[0050] The preparation method of present embodiment 2 comprises following specific steps:

[0051] (1) Lithium carbonate, iron acetate and ammonium dihydrogen phosphate were weighed respectively according to the molar ratio of Li: Fe(II): P=1.10: 1: 1, and 15wt% of microwave absorbing agent of electric conduction and heat conduction was added (according to generating lithium iron phosphate Calculation), β-dextrin 15wt% (calculated by generating lithium iron phosphate) and ethanol;

[0052] (2) high-speed ball milling with agate balls for 6 hours, during ball milling, the mass ratio of each material is: raw material: dispersant: ball=1: 3: 5, forming powder;

[0053] (3) At 80°C, vacuum dry the powder ground in step (1) for 12 hours, and place it in a microwave heating reaction chamber;

[0054] (4) After vacuuming, feed argon to an atmospheric pressure;

[0055] (5) Turn on the microwave power of 1500W and raise the temperature to 700°C;

[0056] (6) Regulate the pyrolysis ...

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Abstract

The invention provides a method for preparing carbon-coated LiFePO4 by microwaves, which comprises the following steps: respectively obtaining a lithium source compound, a ferrous iron source compound and a phosphorous source compound in a stoichiometric ratio of the LiFePO4 required to be prepared, and adding a microwave absorber, an organic carbon source and a liquid dispersant; performing ball milling on the obtained raw material and drying treatment; putting the dried product in a microwave heating reaction cavity, and introducing protective gas into the reaction cavity; and heating to the temperature of between 550 and 850DEG C with the microwaves, introducing carbon source gas, and performing pyrolysis on the carbon source gas at the temperature of between 550 and 850DEG C to prepare the carbon-coated LiFePO4. The invention also provides a carbon-coated LiFePO4 material prepared by the method. The preparation method adopts microwave heating, and the carbon source gas is subjected to pyrolysis, so that the carbon species are deposited on the surface of the LiFePO4 to obtain the complete, uniform and firm carbon-coated LiFePO4; and simultaneously, by the preparation method, the machining property and the electrochemical performance of the LiFePO4 material can be obviously improved.

Description

technical field [0001] The invention relates to a preparation method of carbon materials, in particular to a microwave preparation method of carbon-coated lithium iron phosphate and a carbon-coated lithium iron phosphate material. Background technique [0002] At present, with the accelerated process of industrialization and rapid economic growth, the energy problem has become one of the urgent problems to be solved by human beings. For half a century, scientific research institutions around the world have started to develop new energy sources such as water energy, solar energy, wind energy, and nuclear energy; on the other hand, they have paid more and more attention to the efficient storage and utilization of energy. The existing secondary batteries for storage mainly include lead-acid batteries, cadmium-nickel batteries (Cd / Ni), metal hydride nickel batteries (MH / Ni) and lithium-ion batteries. Among them, lithium-ion batteries have the advantages of high voltage, high sp...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/58H01M4/1397C01B25/45
CPCY02E60/12Y02E60/122Y02E60/10
Inventor 曾燮榕邓飞邹继兆盛洪超黄剑锋
Owner SHENZHEN UNIV
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