Method for producing lithium iron phosphate without inert gas protection

A lithium iron phosphate, inert gas technology, applied in chemical instruments and methods, phosphorus compounds, inorganic chemistry, etc., can solve problems such as low tap density, polluted finished products, and increased pressure, achieve stable charge and discharge performance, and reduce production. The effect of low cost and energy consumption

Active Publication Date: 2009-12-09
YUNNAN NENGTOU HUILONG TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In this invention, as the temperature rises, the material as the precursor will react and release gas, and the invention is covered with a corundum sheet, which is carried out in a relatively airtight container, and there is no channel for the gas to be discharged smoothly , there are the following deficiencies: 1. the gas expands and the pressure rises, causing safety problems; 2. when the invention uses ammonium hydrogen phosphate and ammonium dihydrogen phosphate, the ammonia, water and carbon dioxide produced in the sintering process are in the process of cooling the reaction material boat Ammonium bicarbonate crystal particles will be produced and cause product pollution; ③The precursor body will melt during the roasting process, and the carbon powder will be directly covered on the precursor body, which will cause the carbon powder to stick to the precursor body during sintering, affecting the quality of the final product. quality, and the sinking of the melted precursor causes a space on the top of the reaction boat, and the gas generated by the reaction exists in this space to pollute the finished product; ④The synthesized lithium iron phosphate is loose and porous, so the tap density is low, and the general gram capacity is less than 120mAh / g

Method used

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  • Method for producing lithium iron phosphate without inert gas protection
  • Method for producing lithium iron phosphate without inert gas protection
  • Method for producing lithium iron phosphate without inert gas protection

Examples

Experimental program
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Effect test

Embodiment 1

[0042] Lithium hydroxide: ferrous oxalate: ammonium dihydrogen phosphate is mixed in a molar ratio of 1.1:1:1, and 5% carbon black is added in a mass ratio, placed in a stirring ball mill for 5 hours; fully mixed and ground to prepare Put the precursor body into a stainless steel box, compact the precursor powder with a hydraulic press, cover with a porous stainless steel plate and spread a stainless steel screen with a pore size of less than 100 mesh, put in activated carbon powder larger than 100 mesh and cover with a porous stainless steel plate, Then put it in a vacuum box to evacuate for 0.5 hours, then fill it with high-purity nitrogen, and finally send the precursor into the tunnel kiln for roasting, start heating from room temperature, and the heating rate is 10 °C / min, after heating to 650 °C, roast for 8 hour, and then cooled to room temperature with the furnace, the obtained lithium ferrous phosphate gram capacity is 141mAh / g, and its charge and discharge curve is as...

Embodiment 2

[0044] Lithium carbonate: ferrous oxalate: ammonium dihydrogen phosphate: Mg(OH) 2 Mix at a molar ratio of 0.5:0.95:1:0.05, add 8% glucose by mass ratio, place in a stirring ball mill for mixing and grinding for 5 hours; put the precursor prepared by fully mixing and grinding into a stainless steel box, and use a hydraulic press Compact the precursor powder, cover with a porous stainless steel plate and spread a stainless steel screen with a pore size of less than 100 mesh, put in activated carbon powder larger than 100 mesh, cover with a porous stainless steel plate, and then vacuumize in a vacuum box for 0.5 hours before charging Inject high-purity nitrogen, and finally send the precursor into a tunnel kiln for calcination, start heating from room temperature at a heating rate of 10°C / min, heat to 650°C and then calcine for 8 hours, then cool to room temperature with the furnace, the obtained product The XRD diffraction pattern of Figure 4 As shown, by comparing with the s...

Embodiment 3

[0046] Lithium carbonate and iron phosphate were mixed in a molar ratio of 0.5:1, and 10% glucose was added in a mass ratio, and placed in a stirring ball mill for mixing and grinding for 5 hours; the precursor prepared by fully mixing and grinding was loaded into a stainless steel box, Compact the precursor powder with a hydraulic machine, cover with a porous stainless steel plate and spread a stainless steel screen with a pore size of less than 100 mesh, put in activated carbon powder with a diameter of more than 100 mesh and cover with a porous stainless steel plate, and finally send the precursor into the tunnel kiln Carry out calcination, start heating from room temperature, the heating rate is 10 ℃ / min, after heating to 700 ℃, calcine for 6 hours, then cool to room temperature with the furnace, the gram capacity of the obtained lithium ferrous phosphate is 157mAh / g, and its charge and discharge curve is as follows Image 6 shown.

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Abstract

The invention discloses a method for producing lithium iron phosphate without inert gas protection, aiming at providing a technique for preparing the lithium iron phosphate without needing the inert gas protection in the calcination process, so as to realize the aim of reducing the manufacturing cost of positive material of a lithium iron phosphate battery. The method comprises the steps: the prepared precursor material is put into a semi-enclosed box body and pressed to be compact to exhaust the air in the precursor material; a high temperature resistant plate provided with holes is pressed on the precursor material or a gap is left between the high temperature resistant plate and the box body, and then a carbon dust layer is filled into the high temperature resistant plate; finally, the high temperature resistant plate provided with the slim holes is laid on carbon dust or the gap is left between the high temperature resistant plate and the box body; the box body is placed into a calcination device and heated from the room temperature to be 600-800 DEG C at the speed of 5-20 DEG C/min; after that, the temperature is maintained for 6-24h for calcination, and then the product is cooled to be the room temperature along with a furnace.

Description

technical field [0001] The invention relates to a positive electrode material of a lithium battery, and more particularly to a preparation method of lithium iron phosphate, a positive electrode material of a lithium ion battery. Background technique [0002] Lithium ferrous phosphate is a new electrode material for lithium-ion batteries. Its characteristics are: ① High energy density, the theoretical specific capacity is 170mAh / g, and the actual specific capacity of the product can exceed 140mAh / g (0.2C, 25℃); ② , safe, is currently the safest lithium-ion battery cathode material, does not contain any heavy metal elements harmful to the human body; ③, long life, under 100% DOD conditions, can charge and discharge more than 2000 times; no memory effect; ④, charging Performance, lithium iron phosphate lithium battery as the positive electrode material can be charged at a high rate to achieve fast charging. Although lithium iron phosphate battery has high safety and long life ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/45
Inventor 杨成云
Owner YUNNAN NENGTOU HUILONG TECH
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