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Preparation of ferric phosphate lithium composite material

A composite material, lithium iron phosphate technology, used in phosphorus compounds, chemical instruments and methods, inorganic chemistry, etc., can solve the problems of slow solid-phase diffusion rate of reducing agents, high hydrothermal reaction temperature, and high production costs, and achieves conductive agent. The effect of uniform distribution, stable electrochemical performance and convenient operation

Inactive Publication Date: 2010-05-26
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But since Li + The solid-phase diffusion rate of the reductant and the reducing agent is too slow, and this method requires a longer reaction time or a higher hydrothermal reaction temperature
In actual research, this reduction lithium intercalation process is often carried out by fire roasting at high temperature, the whole process is complicated and the production cost is also high

Method used

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  • Preparation of ferric phosphate lithium composite material
  • Preparation of ferric phosphate lithium composite material
  • Preparation of ferric phosphate lithium composite material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Lithium hydroxide: ferric hydrogen phosphate was mixed at a molar ratio of 1.2:1, and 5% carbon black was added according to the weight ratio of the reaction product, and placed in a vibrating ball mill for mixing and grinding for 1 hour; the grinding product was taken out, put into a porcelain boat, and placed In an electric furnace, under the protection of nitrogen at a flow rate of 5 liters / min, the temperature was raised to 500°C at a rate of 20°C / min, kept at a temperature of 20 hours, and then cooled to room temperature with the furnace, and the obtained product was product A. attached figure 1 It is the XRD pattern of product A, and the result shows that the product is LiFePO 4 , the crystal structure is complete.

[0024] Weigh 0.75 grams of product A, add 0.15 grams of carbon black and 0.1 grams of polytetrafluoroethylene, grind evenly, and prepare electrodes by coating method. Select a suitable positive electrode sheet, use the lithium sheet as the counter e...

Embodiment 2

[0026] Lithium hydroxide: ferric hydrogen phosphate was mixed at a molar ratio of 1:1, and 5% sucrose was added according to the weight ratio of the reaction product, and placed in a roller mill for mixing and grinding for 10 hours; the ground product was taken out, put into a porcelain boat, and placed In an electric furnace, under the protection of argon with a flow rate of 1 liter / min, the temperature is raised to 800°C at a rate of 15°C / min, kept at this temperature for 2 hours, and then cooled to room temperature with the furnace, and the obtained product is product B . attached figure 2 It is the XRD pattern of product B, and the result shows that the product is olivine-type LiFePO 4 ;

[0027] According to the method of Example 1, the battery comprising the electrode made of product B was assembled and tested, and the results showed that its first discharge specific capacity was 147.4mAh / g, and the specific capacity after 10 cycles was 142.8mAh / g.

Embodiment 3

[0029] Lithium carbonate: ferric hydrogen phosphate was mixed at a molar ratio of 0.5:1, and 10% glucose was added in the weight ratio of the reaction product, and placed in a planetary ball mill for mixing and grinding for 2 hours; Under the protection of nitrogen, the temperature was raised to 600°C at a rate of 20°C / min, kept for 12 hours, and then cooled to room temperature at a cooling rate of 3°C / min. The obtained product was product C, and the results showed that the product was LiFePO 4 .

[0030] According to the method of Example 1, the battery comprising the electrode made by product C was assembled, tested at room temperature and 1C current density, the results showed that its initial discharge specific capacity was 143.6mAh / g, and the specific capacity after 20 cycles was 142.8mAh / g. g; the first charge and discharge curve and cycle performance chart are as attached image 3 , attached Figure 4 shown.

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Abstract

The invention discloses a preparation method of lithium iron phosphate composite material which is characterized by adopting ferric hydrogen phosphate as iron source and phosphor source, mixing lithium source (lithium hydroxide, lithium carbonate, lithium oxalate or the like), ferric hydrogen phosphate with doping source materials, replacing the hydrogen in the FeHPO4 with lithium during the mechanochemical reaction in the ball mill, calcining the milled materials under protective atmosphere for several hours and crystallizing to obtain lithium iron phosphate (LiFePO4) composite material. Thepreparation method of the invention simplifies the synthesis technology and reduces the cost of material. The lithium iron phosphate composite material obtained has advantages of high specific capacity and good circulation performance, which is suitable for industrial application.

Description

technical field [0001] The invention belongs to a method for preparing an anode material for an energy material secondary battery, in particular to a method for preparing an anode material for a lithium ion battery. Background technique [0002] LiFePO 4 As a new type of positive electrode material for lithium-ion secondary batteries, it has a high theoretical specific capacity (170mAh / g) and a moderate voltage platform (about 3.4V), and has good cycle performance, low price, and good safety, which has attracted great attention. Attention, it is considered to be a cathode material for lithium-ion batteries with great application potential, especially power lithium-ion batteries. [0003] Usually, the preparation of LiFePO 4 The methods are: [0004] (1) High temperature solid phase method. Synthesis of LiFePO using a high-temperature solid-state method 4 , with ferrous oxalate, ammonium phosphate and lithium carbonate as raw materials, fully ground and calcined at 200-3...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B25/45H01M4/58
CPCY02E60/10
Inventor 赵中伟刘旭恒李洪桂
Owner CENT SOUTH UNIV
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