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Preparation of lithium iron phosphate nano composite microsphere

A technology of lithium iron phosphate and nanocomposite, applied in phosphorus compounds, chemical instruments and methods, electrode manufacturing, etc., can solve the problems of unsatisfactory high-rate performance of battery materials, complex synthesis process, and instability, etc., and is suitable for large-scale industrialization Excellent production and rate performance, high tap density effect

Active Publication Date: 2009-07-08
湖北金泉新材料有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although these methods can also produce spherical lithium iron phosphate, the particle size is relatively large, they are all solid spheres, the diffusion path of lithium ions is long, and the electrolyte cannot infiltrate the interior of the particles, resulting in unsatisfactory high-rate performance of the battery material. The process is complex and the steps are cumbersome, requiring intermediate steps such as centrifugation, washing, and ball milling
In the invention patent with the application number of 200710058352.2 "a hydrothermal synthesis method of lithium iron phosphate cathode material for lithium ion batteries", a hydrothermal method for preparing lithium iron phosphate is disclosed. The method is to combine lithium source, iron source, The phosphorus source is made by mixing hydrothermally with a molar ratio of 3:1:1, and the product is an agglomerate composed of flake particles. This method has a large excess of lithium source, which causes a lot of waste, and must use expensive and unstable ferrous ions Fe 2+ For iron source, increased production cost

Method used

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  • Preparation of lithium iron phosphate nano composite microsphere
  • Preparation of lithium iron phosphate nano composite microsphere
  • Preparation of lithium iron phosphate nano composite microsphere

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0058] Example 1 LiFePO 4 Preparation of nanocomposite microspheres

[0059] 1.18g LiOH·H 2 O, 11.3g Fe(NO 3 ) 3 ·6H 2 O, 2.74g H 3 PO 4 Mix well, make 70ml aqueous solution, pour into 100ml Teflon-lined stainless steel reaction kettle, conduct hydrothermal reaction at 150°C for 24h, cool naturally to room temperature, remove all solvents to obtain precursor. Put the precursor in a tube furnace and burn it at 600 °C for 10 h under the protective atmosphere of high-purity argon to obtain the target product LiFePO 4 .

[0060] figure 1 For the resulting LiFePO 4 The SEM image of the material shows that the material synthesized by this method has a uniform and regular spherical structure with a particle size of 2-3 μm, and each microsphere is formed by the aggregation of nanoparticles of about 100 nm. There are abundant pores on the surface and inside of the microspheres, which are conducive to electrolyte infiltration.

Embodiment 2

[0061] Example 2 Carbon-coated LiFePO 4 Preparation of nanocomposite microspheres

[0062] 0.60g LiCl, 3.55g Fe 2 (SO 4 ) 3 ·6H 2 O, 1.61 g NH 4 h 2 PO 4 Mix well with 2g citric acid to make 70ml aqueous solution, pour it into a 100ml Teflon-lined stainless steel reaction kettle, conduct a hydrothermal reaction at 200°C for 3 hours, cool naturally to room temperature, and remove all solvents to obtain a precursor. Add 30% mass of polyethylene glycol to the precursor, mix it evenly, place it in a tube furnace, and burn it at 650°C for 20h under a high-purity argon protective atmosphere to obtain the target product LiFePO 4 / C.

[0063] figure 2 For the obtained LiFePO 4 SEM image of / C material, and figure 1 Similar obtained materials also have a spherical structure with a particle size of 2-3 μm, and the surface is relatively figure 1 smoother, indicating that the organic pyrolytic carbon can be 4 A complete and uniform coating layer is formed on the surface. Th...

Embodiment 3

[0064] Example 3, LiFe 0.98 Mg 0.02 PO 4 Preparation of nanocomposite microspheres

[0065] 4.46g FeCl 3 , 3.22 g NH 4 h 2 PO 4 , 0.14g Mg(NO 3 ) 2 ·6H 2 O mixed evenly, made into a 70ml aqueous solution, poured into a 100ml stainless steel reactor with Teflon lining, reacted hydrothermally at 130°C for 6h, cooled naturally to room temperature, removed all solvents to obtain a precursor, added to the precursor 1.23g LiOH·H 2 O and 25% mass of glucose, mixed evenly, placed in a tube furnace, and burned at 650°C for 20h under a nitrogen-hydrogen mixture containing 5% hydrogen to obtain the target product LiFe 0.98 Mg 0.02 PO 4 / C.

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Abstract

The invention discloses a method for preparing a lithium iron phosphate nano composite microsphere for a lithium-ion secondary battery anode material by a hydrothermal method, which comprises the following steps: evenly mixing a lithium source, an iron source and a phosphoric acid source according to the stoichiometric ratio of 1-1.05:1:1 to prepare an aqueous solution with certain concentration, adding proper amount of reducing agent, carbonizing agent, ion dopant and the like into the aqueous solution, growing and curing crystals under high-temperature hydrothermal condition, removing a solvent from a hydrothermal product, and burning the hydrothermal product in inert or reducing atmosphere to obtain a final product. The lithium iron phosphate anode material prepared by the method has a regular nano composite microsphere structure, has a particle diameter of between 2 and 4 mu m, even distribution, tap density up to 1.3 to 1.6 g / cm, and has excellent cycle performance and multiplying power performance. The method has simple and easily-controlled process, can use cheap trivalent iron as the iron source, can obtain rich raw materials, and is a practical technique for preparing lithium iron phosphate.

Description

technical field [0001] The invention relates to a preparation method of a positive electrode material of a lithium ion secondary battery, in particular to the preparation of lithium iron phosphate nanocomposite microspheres by a hydrothermal method, and belongs to the field of energy materials and technologies. Background technique [0002] In recent years, due to its excellent electrochemical performance and safety and pollution-free characteristics, lithium-ion batteries have developed rapidly and achieved great commercial success, and are widely used in cameras, mobile phones and notebook computers. At present, the positive electrode materials used and researched in lithium-ion batteries are all lithium-intercalable compounds, generally including layered LiCoO 2 , LiNiO 2 , LiMnO 2 , spinel LiMn 2 o 4 and LiFePO with olivine structure 4 Wait. [0003] Olivine LiFePO 4 With its rich raw materials, low price, high specific capacity, good cycle performance, and low en...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/45H01M4/58H01M4/04H01M4/36H01M4/40
CPCY02E60/12Y02E60/10
Inventor 曹余良杨汉西钱江锋周敏艾新平
Owner 湖北金泉新材料有限公司
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