Method of preparing positive electrode composite material of Lithium ion cell contg, ferrous phosphate lithium salt-carbon

A technology for lithium ferrous phosphate and lithium-ion batteries, which is applied in electrode manufacturing, battery electrodes, phosphorus compounds, etc. It can solve the problems of difficult control of product purity, complicated preparation process, and high price, and achieve excellent cycle performance and high purity. , cheap effect

Inactive Publication Date: 2005-01-12
宜春天赐高新材料有限公司
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AI-Extracted Technical Summary

Problems solved by technology

However, the conductivity of this material is very poor, and it can only be charged and discharged at a very small rate at room temperature, and its preparation requires Fe 2+ As iron source, the price is higher than Fe 3+ The salt is ...
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Abstract

The preparation method includes following procedures: mixing certain proportional lithium salt, Fe3+ compound and phosphate evenly by using one-step solid phase method; with a given amount of high polymer being added, in atmosphere of inert gases, pyrolyzing admixture obtains composite material of lithium salt-carbon anode based on ferrous phosphate. Features are: no need of expensive Fe2+, simple technique, ans safe. High purity of composite material, high specific capacity and cycle performance, providing 3.4V power source for mobile phone etc.

Application Domain

Technology Topic

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  • Method of preparing positive electrode composite material of Lithium ion cell contg, ferrous phosphate lithium salt-carbon
  • Method of preparing positive electrode composite material of Lithium ion cell contg, ferrous phosphate lithium salt-carbon
  • Method of preparing positive electrode composite material of Lithium ion cell contg, ferrous phosphate lithium salt-carbon

Examples

  • Experimental program(4)

Example Embodiment

[0017] Example 1
[0018] Mix 0.5 mol of lithium hydroxide and 0.5 mol of iron phosphate, put them in a nylon tank, and add 80 ml of alcohol. After mixing for 2 hours on a ball mill, the mixture is mixed into 14 grams of polypropylene and placed in a tube furnace. Under a nitrogen atmosphere of 1 liter/min, the temperature was increased to 700° C. at a rate of 5° C./min, and the temperature was kept constant for 10 hours, and then the temperature was lowered to room temperature.
[0019] The carbon content of the obtained composite material is 2.5%, and the XRD spectrum is shown in figure 1 , Compared with the standard card, it is olivine LiFePO with intact crystal form 4 , And no diffraction peak of carbon is observed.
[0020] The composite material obtained in Example 1 was used to prepare electrodes in the following manner.
[0021] Weigh the composite material obtained in Example 1 at a mass ratio of 80:10:10: carbon black: polytetrafluoroethylene, grind uniformly to make an electrode, with a pure lithium sheet as the negative electrode to dissolve in ethyl carbonate + carbonic acid 1.0mol/L LiPF in a mixed solvent of dimethyl ester (1∶1 by volume) 6 It is the electrolyte, and the polypropylene microporous film is the diaphragm, assembled into a simulated lithium-ion battery. figure 2 For the first charge-discharge curve of the corresponding battery at a cut-off voltage of 4.2V-2.5V at a rate of 0.1C, indicating that the tested battery has a stable charge-discharge voltage platform of about 3.4V, the reversible specific capacity of the composite material in Example 1 can be calculated It is 164mAh/g. image 3 Is the discharge curve of the corresponding battery at different charge and discharge rates. In the discharge rate range of 0.1C-0.5C, the reversible capacity of the positive electrode active material is between 4145-164 mAh/g. Figure 4 It is the cycle performance of the corresponding battery at a rate of 0.2C. Among them, the specific capacity is LiFePO 4 Mass calculation instead of LiFePO 4 -The quality of the carbon composite is the same in the following examples.

Example Embodiment

[0022] Example 2:
[0023] Mix 0.5 mol of lithium hydroxide, 0.25 mol of ferric oxide and 0.5 mol of ammonium dihydrogen phosphate into a nylon tank, add 80 ml of alcohol, mix thoroughly on a ball mill for 2 hours, and mix the mixture into 20 grams The polypropylene was put into a tube furnace, and under a nitrogen atmosphere of 5 liters/minute, the temperature was raised to 700°C at a rate of 5°C/minute, and the temperature was kept constant for 20 hours, and then the temperature was lowered to room temperature. The carbon content of the obtained composite material was measured to be 4.6%. The electrode sheet was also prepared according to the method of Example 1. After being assembled into a battery, it was charged and discharged at a rate of 0.2C, and the reversible capacity was determined to be 157mAh/g.

Example Embodiment

[0024] Example 3:
[0025] Mix 0.5 mol of lithium hydroxide and 0.5 mol of iron phosphate, put them in a nylon tank, and add 80 ml of alcohol. After mixing on a ball mill for 1 hour, the mixture is mixed with 25 grams of polyethylene and placed in a tube furnace. Under a nitrogen atmosphere of 1 liter/min, the temperature was increased to 500° C. at a rate of 5° C./min, and the temperature was kept constant for 24 hours, and then the temperature was lowered to room temperature. The carbon content of the obtained composite material was measured to be 3.1%, and the electrode sheet was prepared according to the method of Example 1. After being assembled into a battery, the battery was charged and discharged at a rate of 0.5C, and the reversible capacity was determined to be 148mAh/g.
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PUM

PropertyMeasurementUnit
Reversible capacity164.0 ~ 4145.0ah/g
tensileMPa
Particle sizePa
strength10

Description & Claims & Application Information

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