Hydrothermal synthesis method for preparing iron phosphate lithium as anode material of lithium ion battery

A lithium-ion battery, lithium iron phosphate technology, applied in battery electrodes, circuits, electrical components, etc., can solve the problems of low bulk density, low volume specific capacity, low specific capacity, etc., and achieve easy control of process parameters and excellent battery performance. , the effect of uniform particle distribution

Inactive Publication Date: 2010-06-30
孙琦
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AI-Extracted Technical Summary

Problems solved by technology

However, due to two disadvantages of lithium iron phosphate: one is low electrical conductivity, resulting in poor high-rate charge and discharge performance and low ...
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Abstract

The invention relates to a hydrothermal synthesis method for preparing iron phosphate lithium as an anode material of lithium ion battery, which belongs to the technical field of new energy materials. The hydrothermal synthesis method comprises the following steps of: mixing an iron source with phosphate, adding a lithium source, and after uniform agitation, putting the mixture into a high-pressure reaction kettle; then, adding a reducing agent, and maintaining the temperature at 180-200 DEG C for 8-12 h to produce spherical iron phosphate lithium, wherein the mol ratio of the lithium source to the iron source to the phosphate is 3:1:1. The invention provides a simple and one-step method for directly preparing iron phosphate lithium. The technological parameters of the method used for preparation are easily controlled; compared with a process using ferric iron as a raw material, the resource of ferrous iron as the raw material is wider; the prepared iron phosphate lithium powder particles have small mean particle diameter which is about 3-5 mu m, the particles are evenly distributed, the tap density can reach 2.0-2.5 g/cm<3>, the battery performance is high, and the specific capacity for the first charge and discharge cycle is 140-160 mAh/g.

Application Domain

Technology Topic

Examples

  • Experimental program(5)

Example Embodiment

[0014] Example 1:
[0015] 1. Configure iron source and phosphorus source aqueous solution, where the concentration of iron is 0.1-2 mol/liter, the concentration of phosphorus is phosphorus: iron = (1.0-1.5): 1, configure the lithium source solution, the concentration is lithium: iron = 3 :1.
[0016] 3. Mix the above iron source solution and phosphorus source solution, move them into the autoclave, and stir for 10 minutes.
[0017] 4. Slowly add the prepared lithium source solution to the mixed solution in the autoclave and stir.
[0018] 5. Add the reducing agent with a mass ratio of 15%-30% into the mixed solution, adjust the PH value between 5.0-8.0 with acetic acid, and stir for 1-2 hours.
[0019] 6. Seal the autoclave, heat it up to 180℃-200℃, keep it for 8-12h. Cool down naturally to room temperature.
[0020] 7. Wash the obtained product with distilled water for 5-10 times, disperse with ethanol, and place it in a drying oven at 70°C-90°C for drying.
[0021] In the above preparation method 1, the iron source is one of ferrous acetate, ferrous oxalate, and ferrous sulfate.
[0022] In the above preparation method 1, the phosphorus source is one of ammonium dihydrogen phosphate and diammonium hydrogen phosphate.
[0023] In the above preparation method 2, the lithium source is one of lithium carbonate, lithium hydroxide, lithium nitrate, lithium acetate, and lithium oxalate.
[0024] In the above preparation method 5, the reducing agent is one of sodium sulfite, ascorbic acid, and sucrose.

Example Embodiment

[0025] Example 2:
[0026] Prepare 0.3M lithium hydroxide, 0.1M diammonium hydrogen phosphate, 0.1M ferrous oxalate aqueous solution, and weigh 10g sucrose. Transfer the solution of ferrous oxalate and ammonium dihydrogen phosphate into the autoclave and stir with a stirrer for 10 minutes. Put the lithium hydroxide solution into the autoclave, add sucrose, continue stirring for 1 hour, adjust the pH 5.0-8.0 with acetic acid, and seal the autoclave. Raise the temperature to 180°C and keep it for 8h. Then the reaction kettle is naturally cooled and set to room temperature, the obtained product is washed 5-10 times with distilled water, dispersed with ethanol, and dried in a drying box at 70°C. The obtained lithium iron phosphate product was tested by SEM and electrical performance test, and the SEM showed that the particle size was about 3 μm and the particle distribution was uniform. The measured tap density of the product is 2.0 g/cm3. Using the lithium sheet as the negative electrode, the first discharge specific capacity of lithium iron phosphate at room temperature was measured to be 140mAh/g.

Example Embodiment

[0027] Example 3:
[0028] Prepare 0.45M lithium hydroxide, 0.15M diammonium hydrogen phosphate, 0.15M ferrous oxalate aqueous solution, and weigh 20g sucrose. Transfer the ferrous oxalate and ammonium dihydrogen phosphate solution into the autoclave and stir with a stirrer for 10 minutes. Put the lithium hydroxide solution into the autoclave, add ascorbic acid, continue stirring for 1.5 hours, adjust the pH 5.0-8.0 with acetic acid, and seal the autoclave. Raise the temperature to 200°C and keep it for 8 hours. Then the reaction kettle was naturally cooled and set to room temperature, and the obtained product was washed 5-10 times with distilled water, dispersed with ethanol, and dried in a drying box at 80°C. The obtained lithium iron phosphate product was tested by SEM and electrical performance test, and the SEM showed that the particle size was about 4 μm and the particle distribution was uniform. The measured tap density of the product is 2.4 g/cm3. Using the lithium sheet as the negative electrode, the first discharge specific capacity of lithium iron phosphate at room temperature was measured to be 150mAh/g.
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PUM

PropertyMeasurementUnit
Particle size3.0µm
Tap density2.0g/cm³
First discharge specific capacity140.0mAh/g
tensileMPa
Particle sizePa
strength10

Description & Claims & Application Information

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