Method for producing lithium iron phosphate

Abstract

The invention discloses a method for producing lithium iron phosphate without inert atmosphere protection, aiming at realizing 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 which is higher than the box body is arranged, and a gap is left between the high temperature resistant plate and the box body; then, the semi-enclosed box body and the high temperature resistant plate are arranged inside another semi-enclosed box body in a inverted way, and a carbon dust layer is filled into the box body; 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 obtained semi-enclosed box body that is provided with the precursor and the carbon dust is firstly vacuumized and then filled with non-oxidizing gas for replacing the air in the precursor and the carbon dust; 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 ...

AI Technical Summary

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 ferrous phosphate is loose and porous, so the tap density is low, and the general gram capacity is less than 120mMh / g

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