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One-step preparation method of LiFePO4 powder coated with carbon

A carbon coating and powder technology, which is applied in the field of energy material preparation, can solve problems affecting material purity and tap density, difficulty in controlling product batch stability, and limiting material industrial production, etc., to improve electrochemical performance and morphology Uniform, short cycle effect

Inactive Publication Date: 2009-10-28
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

To ensure Fe 3+ Full reduction, this kind of reaction process requires high temperature, long cycle and needs to introduce excessive carbon source, which seriously affects the purity and tap density of the material, sometimes requires secondary calcination, it is difficult to control the batch stability of the product, and the carbon source The selection requirements are high, which limit the industrial production of materials

Method used

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  • One-step preparation method of LiFePO4 powder coated with carbon
  • One-step preparation method of LiFePO4 powder coated with carbon
  • One-step preparation method of LiFePO4 powder coated with carbon

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Using phosphoric acid, lithium hydroxide monohydrate, ferrous sulfate heptahydrate, gelatin and ascorbic acid as raw materials, according to the molar ratio of lithium hydroxide monohydrate, phosphoric acid and ferrous sulfate heptahydrate as 3:1:1, accurately weigh 2.224g Ferrous sulfate heptahydrate, 1.001g lithium hydroxide monohydrate, 0.55ml phosphoric acid (mass percentage is 85%), take by weighing 0.08g gelatin and 0.04g antioxidant ascorbic acid, the two account for 6% of the theoretically synthesized lithium ferrous phosphate quality respectively % and 3%. The above substances were prepared into phosphoric acid solution, lithium hydroxide monohydrate solution and ascorbic acid solution respectively, and dissolved in deionized water at 40° C. to obtain gelatin aqueous solution. The phosphoric acid solution and the lithium hydroxide monohydrate solution are uniformly mixed to obtain lithium phosphate precipitation, and the pH of the reaction process is controlled...

Embodiment 2

[0025]Using phosphoric acid, lithium hydroxide monohydrate, ferrous sulfate heptahydrate, gelatin and ascorbic acid as raw materials, according to the molar ratio of lithium hydroxide monohydrate, phosphoric acid and ferrous sulfate heptahydrate as 3:1:1, accurately weigh 2.224g Ferrous sulfate heptahydrate, 1.001g lithium hydroxide monohydrate, 0.55ml phosphoric acid (mass percentage is 85%), take by weighing 0.013g gelatin and 0.040g antioxidant ascorbic acid, the two account for 1% of the theoretically synthesized lithium iron phosphate quality respectively % and 3%. The above substances were prepared into phosphoric acid solution, lithium hydroxide monohydrate solution and ascorbic acid solution respectively, and dissolved in deionized water at 40° C. to obtain gelatin aqueous solution. The phosphoric acid solution and the lithium hydroxide monohydrate solution are uniformly mixed to obtain lithium phosphate precipitation, and the pH of the reaction process is controlled a...

Embodiment 3

[0028] Using phosphoric acid, lithium hydroxide monohydrate, ferrous sulfate heptahydrate, gelatin and ascorbic acid as raw materials, according to the molar ratio of lithium hydroxide monohydrate, phosphoric acid and ferrous sulfate heptahydrate as 3:1:1, accurately weigh 2.224g Ferrous sulfate heptahydrate, 1.001g lithium hydroxide monohydrate, 0.55ml phosphoric acid (mass percentage is 85%), take by weighing 0.013g gelatin and 0.013g antioxidant ascorbic acid, both account for 1% of the theoretical synthesis lithium iron phosphate quality %. The above substances were prepared into phosphoric acid solution, lithium hydroxide monohydrate solution and ascorbic acid solution respectively, and dissolved in deionized water at 40° C. to obtain gelatin aqueous solution. The phosphoric acid solution and the lithium hydroxide monohydrate solution are uniformly mixed to obtain lithium phosphate precipitation, and the pH of the reaction process is controlled at 7-9. Dissolve ferrous s...

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Abstract

The invention relates to a one-step preparation method of LiFePO4 powder coated with carbon. Lithium compounds, ferrite and phosphorous compounds are taken as raw materials, additive is antioxidant and glutin that accounts for 1-6% of the mass of theoretically generated lithium ferrous phosphate; the glutin is dissolved in de-ionized water which is then heated and stirred at the temperature of more than 40 DEG C to obtain the aqueous solution of the glutin. The prepared ferrite solution and the glutin solution are added to a Li3PO4 system to be mixed uniformly; the mixed solution reacts at the temperature of 120-170 DEG C for 2-5h; the obtained product is dry lithium ferrous phosphate powder coated with the glutin; the prepared powder is filled in a quartz crucible and calcined at the temperature of 550-750 DEG C under the protection of N2 atmosphere, and finally the lithium ferrous phosphate powder coated with carbon is obtained. The shape of the prepared lithium ferrous phosphate particles is uniform and columnar with the grain diameter being 400nm, the surface coating is thin and uniform amorphous carbon, has high tap density, is beneficial to improving the electrochemical performance of materials and is suitable for being used as anode material. The method has simple process route and no pollution and is suitable for scale production.

Description

technical field [0001] The invention relates to a one-step carbon-coated LiFePO 4 The preparation method of powder belongs to the technical field of energy material preparation. Background technique [0002] Lithium iron phosphate (LiFePO 4 ) material has the characteristics of abundant raw materials, cheap price, non-hygroscopicity, non-toxicity, environmental friendliness, high specific capacity (theoretical capacity is 170mA h / g), good stability, etc. It is a kind of lithium battery with great potential It is a substitute material for positive electrode materials and has broad application prospects and great market demand. The main reason restricting lithium ferrous phosphate as positive electrode material is the low conductivity of lithium ferrous phosphate material itself. The low conductivity seriously affects the charge and discharge current density and specific capacity of the material, which restricts the practical application of ferrous phosphate. In recent yea...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/04H01M4/58H01M4/62
CPCY02E60/12Y02E60/10
Inventor 蔡舒周幸苗利娟周维翟羽佳
Owner TIANJIN UNIV
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