Solid-phase method for preparation of high-density spherical-like ferric phosphate lithium

Abstract

The invention relates to a solid phase preparation method of high density spherelike lithium iron phosphate, pertaining to battery field, and comprising the steps that: element molar ratio of iron sources: phosphorus sources: lithium sources is 1:1:1-1.01, and the molar ratio of doped metals is 0.01-0.03, then 0.1 to 10 percent molar ratio of crystal nucleus growth agent is weighted and mixed withdeionized water and wet milled for 4 to 8 hours, after being taken out, is dried in a vacuum drying box at 80 to 120 DEG C, and with the protection of nitrogen, is pre-decomposed for 2 to 10 hours under temperature of 250 DEG C to 400 DEG C and then is reacted and synthesized for 18 to 26 hours under 650 to 720 DEG C, then the synthesized products are evenly mixed with 1 to 15 percent conductivematerials or organic carbon sources, and covered with carbon for 6 to 16 hours with the protection of 500 to 680 DEG C nitrogen and the temperature is reduced to 80 DEC C or less at a speed of 5 to 10DEG C per minute, finally, the modified product covered with carbon is taken out. The high density carbon covered spherelike lithium iron phosphate of the invention produced by the solid phase production technique has the highest tap density with 15 to 40 percent improvement based on ordinary solid phase production technique, besides, the ratio between volume and capacity of the material is 15 to40 percent higher than ordinary materials.

Description

technical field [0001] The invention discloses a solid-phase preparation method of high-density quasi-spherical lithium iron phosphate, which belongs to the field of batteries. In particular, the invention relates to a solid-phase preparation method of spherical-shaped lithium iron phosphate which is a cathode material of a lithium-ion battery. Background technique [0002] Lithium-ion batteries have many advantages such as high voltage, high energy density, good cycle performance, small self-discharge, no memory effect, wide operating temperature range, etc., and are widely used in mobile phones, notebook computers, UPS, camcorders, various portable electric Tools, electronic instruments, weapons and equipment, etc. also have good application prospects in electric vehicles, and are high-tech products that are of great significance to the national economy and people's lives in the 21st century. [0003] Cathode materials are an important part of lithium-ion batteries. Curr...

AI Technical Summary

Problems solved by technology

This method has obvious disadvantages. First, the doped impurity metal compound or carbon source cannot be fully and uniformly mixed with the lithium source, phosphorus source, and iron source, and the effect of sufficient doping cannot be achieved, and the conductivity of the material is not significantly improved.

The second is that even if the electrical conductivity of the synthesized powder material is improved, the tap density is low, and the general tap density is only 1.0-1.25g / cm 3 , than lithium cobalt oxide (general tap density 2.2-2.59g / cm 3 Resistance, high up to 2.8-2.99g / cm 3 ) is much lower, and the low bulk density makes the volume specific capacity of lithium iron phosphate much lower than that of lithium cobalt oxide material, which has no advantage at all, hindering the practical application development of this material

Its advantage is that the tap density of lithium iron phosphate material is improved, which can generally reach 1.8-2.2g / cm3, but the wet production of lithium iron phosphate material requires high equipment, high process control requirements, and a large amount of wastewater treatment, which is not suitable For mass production and commercial production

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