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Preparation method of pure-phase high-crystallinity lithium iron phosphate

A technology with high crystallinity and lithium iron phosphate, which is applied in chemical instruments and methods, phosphorus compounds, inorganic chemistry, etc., can solve problems such as low crystallinity, harsh conditions, and complicated processes, and achieve simple equipment, reduced energy consumption, and diffraction high intensity effect

Inactive Publication Date: 2012-01-04
HEBEI UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide a preparation method of lithium iron phosphate with pure phase and high crystallinity, using anionic surfactant sodium dodecylsulfonate as template agent, and using it in ethylene glycol-water system Preparation of lithium iron phosphate powder with pure phase and high crystallinity by reflux method to overcome the disadvantages of complex process, harsh conditions, high cost, low crystallinity and low purity of the existing preparation method of lithium iron phosphate powder

Method used

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  • Preparation method of pure-phase high-crystallinity lithium iron phosphate
  • Preparation method of pure-phase high-crystallinity lithium iron phosphate
  • Preparation method of pure-phase high-crystallinity lithium iron phosphate

Examples

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Embodiment 1

[0026] (1) Dissolve 0.02mol of ferrous sulfate in 10mL of water, then add 20mL of ethylene glycol to form a mixture of ferrous sulfate-water-alcohol, add it to a flask with a reflux device, stir it evenly, and set aside ;

[0027] (2) Dissolve 2g of sodium dodecylsulfonate in 10mL of water, and then add 20mL of ethylene glycol to form a mixture of sodium dodecylsulfonate-water-alcohol for later use;

[0028] (3) Dissolve 0.02mol of diammonium hydrogen phosphate in 10mL of water, then add 20mL of ethylene glycol to prepare a mixed solution of diammonium hydrogen phosphate-water-alcohol for use;

[0029] (4) Dissolve 0.02mol of lithium hydroxide in 10mL of water, then add 20mL of ethylene glycol to prepare a lithium hydroxide-water-alcohol mixture for use;

[0030] (5) Preheat the mixed solution prepared in steps (2), (3), and (4) to 60°C, quickly add them to the flask in step (1) successively, and raise the temperature to 118°C under nitrogen protection, Reflux reaction for 2...

Embodiment 2

[0036] The diammonium hydrogen phosphate in the step (3) in the embodiment 1 is replaced by the ammonium dihydrogen phosphate, and other steps are with embodiment 1. The obtained product was 2.95 g of pure-phase high-crystallinity lithium iron phosphate powder, the crystal state and structure of which were the same as in Example 1. The initial discharge capacity at 0.2C was 152.5 mAh / g.

Embodiment 3

[0038] The diammonium hydrogen phosphate in the step (3) in the embodiment 1 is replaced by phosphoric acid, and other steps are with embodiment 1. The obtained product was 2.97g of pure-phase high-crystallinity lithium iron phosphate powder, the crystal state and structure of which were the same as in Example 1. The initial discharge capacity at 0.2C was 152.8mAh / g.

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Abstract

The invention relates to a preparation method of pure-phase high-crystallinity lithium iron phosphate, which comprises the following steps: sequentially adding sodium dodecylsulfate-water-glycol mixed liquid, phosphorus source-water-glycol mixed liquid and lithium source-water-glycol mixed liquid quickly to a flask filled with ferrite-water-glycol mixed liquid, heating up under the protection of nitrogen gas, and performing a refluxing reaction for 12-36 hours; and carrying out standing and water washing for the raw liquid at room temperature, carrying out filtration or centrifugal separation, and drying to obtain pure-phase high-crystallinity lithium iron phosphate powders. The lithium iron phosphate obtained by the method has good crystallinity and pure phase and overcomes the defects of lower crystallinity and impurity doping of the traditional lithium iron phosphate. Besides, the crystallinity is improved without a calcination process so as to save the energy consumption, and the refluxing equipment is simple without using high-pressure equipment. The reaction temperature is 112-118 DEG C, the azeotropic temperature of the glycol-water mixed solvent, which is much lower than the common hydrothermal synthesis temperature (200 DEG C), thereby greatly reducing the energy consumption.

Description

technical field [0001] The technical solution of the invention belongs to the positive electrode material of lithium ion batteries, and relates to a preparation method of pure-phase high-crystallinity lithium iron phosphate. Background technique [0002] Due to the advantages of high energy density and excellent cycle performance, lithium-ion secondary batteries have received extensive attention in the battery field. At present, great progress has been made in the negative electrode materials and electrolyte systems of lithium-ion batteries, while the development of positive electrode materials is relatively backward, which affects the powerization process of lithium-ion batteries. The cathode materials of lithium-ion batteries mainly include layered LiMO 2 (M=Co, Ni, Mn) and spinel LiMn 2 o 4 , where commercial LiCoO 2 Resource is scarce, expensive and toxic; LiNiO 2 Preparation is difficult and there are safety issues; LiMn 2 o 4 The cyclability and high temperature...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B25/45
Inventor 刘超赵珊珊纪秀杰李松马东霞
Owner HEBEI UNIV OF TECH
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