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Microwave process of ferrous lithium phosphate with ferric phosphate

A technology of lithium iron phosphate and iron phosphate, applied in chemical instruments and methods, phosphorus compounds, inorganic chemistry, etc., can solve the problems of material bubbles, battery performance influence, etc., achieve uniform phase, short synthesis cycle, powder particle size small diameter effect

Inactive Publication Date: 2009-04-15
SICHUAN NORMAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the synthesis time of this method is very short, the gases generated during the preparation (mainly carbon dioxide, ammonia and water vapor) will make LiFePO 4 Bubbles appear in the material, which will have a certain impact on the performance of the battery

Method used

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  • Microwave process of ferrous lithium phosphate with ferric phosphate
  • Microwave process of ferrous lithium phosphate with ferric phosphate
  • Microwave process of ferrous lithium phosphate with ferric phosphate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] The method for preparing lithium iron phosphate by iron phosphate microwave in this embodiment mainly includes the following steps:

[0024] (1) Take 0.1 moles of reduced iron powder, 0.1 moles of lithium phosphate, and 0.2 moles of iron phosphate, mix them with a planetary ball mill for high-speed ball milling for 6 hours, press into tablets, put them into a tube furnace, and open them with nitrogen gas for 10 minutes to exhaust the air Power supply, raise the furnace temperature to about 400°C, under the protection of nitrogen, turn off the power supply after 6 hours of roasting, and naturally cool to room temperature to obtain the pre-synthesized precursor;

[0025] (2), take out the precursor obtained in step (1) and ball mill it with a planetary ball mill for 2 hours, press it into tablets, put it into a corundum crucible, cover the precursor with activated carbon, adjust the power of the household microwave oven to 700W, and use activated carbon as the absorber He...

Embodiment 2

[0028] The method for preparing lithium iron phosphate by iron phosphate microwave in this embodiment mainly includes the following steps:

[0029] (1) Mix 0.1 mol of reduced iron powder, lithium phosphate and 0.2 mol of iron phosphate, add an appropriate amount of absolute ethanol as a dispersant, use a planetary ball mill for high-speed ball milling for 4 hours, put the tablet into a vacuum tube furnace, pump After vacuuming, turn on the power, raise the temperature of the furnace to 500°C, bake for 8 hours, then turn off the power, and let it cool down to room temperature naturally to obtain the pre-synthesized precursor;

[0030] (2) Take out the precursor body obtained in step (1), weigh 10 grams and ball mill it with a planetary ball mill for 6 hours, press into tablets, put it into a corundum crucible, cover the precursor body with activated carbon, put it into a household microwave oven, use activated carbon as The medium is heated by absorbing microwaves, the power of...

Embodiment 3

[0033] The method for preparing lithium iron phosphate by iron phosphate microwave in this embodiment mainly includes the following steps:

[0034] (1) Mix 0.11 mol of reduced iron powder, 0.09 mol of lithium phosphate and 0.20 mol of iron phosphate, add an appropriate amount of absolute ethanol as a dispersant, use a ball mill for high-speed ball milling for 10 hours, put the tablet into a tube furnace, and blow nitrogen After exhausting the air for 10 minutes, turn on the power, raise the temperature of the furnace to 300°C, under the protection of nitrogen, bake for 12 hours, then turn off the power, then cool naturally to room temperature to obtain the pre-synthesized precursor;

[0035] (2) Take out the precursor body obtained in step (1), weigh 10 grams of ball mill for 1 hour, press into tablets, put it into a corundum crucible, cover the precursor body with graphite, put it into a household microwave oven, use graphite as the wave-absorbing heating medium, Adjust the p...

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Abstract

The microwave process of preparing ferrous lithium phosphate with ferric phosphate includes the following steps: 1. mixing reduced iron powder, lithium phosphate and ferric phosphate in the molar ratio of 0.9-1.1 to 0.9-1.1 to 1.8-2.2, high speed ball milling for 2-10, tabletting and roasting in a tubular furnace in inert atmosphere or vacuum condition at 300-500 deg.c for 4-12 hr to obtain the precursor; and 2. ball milling the precursor for 1-6 hr, tabletting, setting into crucible and covering with medium, heating in a microwave oven of 350-700 W power for 2-12 min, ball milling for 2-6 hr, and 400 mesh sieving to obtain ferrous lithium phosphate product. The ferrous lithium phosphate product has excellent performance, homogeneous phase, small grain size and other advantages.

Description

technical field [0001] The invention belongs to the technical field of preparation of positive electrode materials of lithium ion batteries, and in particular relates to a method for preparing lithium ferrous phosphate by using iron phosphate microwaves. Background technique [0002] In 1997, under the guidance of Professor J.B.Goodenough of Texas State University, A.K.Padhi found that LiFePO 4 Under the condition of 3.5V (vs. Li / Li+), the specific capacity of 100~110mAh / g can be obtained. Although this value is only 60% of the theoretical specific capacity of 170mAh / g, it is close to the actual specific capacity level of lithium cobalt oxide, a cathode material for lithium batteries commercialized at that time. Moreover, its charge and discharge curve is very flat, and the material is in the state of FePO during charge and discharge. 4 / LiFePO 4 Two-phase coexistence state, and the difference in volume change between the two phases is very small, which indicates that the...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B25/45H01M4/58
CPCY02E60/12Y02E60/10
Inventor 薛卫东许芳伟
Owner SICHUAN NORMAL UNIV