LiFePO4 positive electrode material modified jointly by doping and coating and preparation method thereof

Abstract

The invention provides a LiFePO4 positive electrode material modified jointly by doping and coating, and the LiFePO4 positive electrode material is modified jointly by iron doping and oxide coating. The raw materials comprise a lithium source Li2CO3, an iron source Fe2O3, a vanadium source NH4VO3, a phosphorus source NH4H2PO4, a carbon source glucose and oxide-coated acetates or esters. The acetates comprise cobalt acetate, zinc acetate or nickel acetate, and the esters comprise tetraethyl orthosilicate or zirconic acid diethyl ester. The specific method comprises the following steps: carrying out ball milling on the lithium source, the vanadium source, the iron source and the phosphorus source and then pre-roasting, carrying out carbon source ball milling and sintering, re-sintering the product after the sintered product is dissolved with the acetates or esters, and stirring the sintered sample, and then smearing the stirred sample on an aluminum foil, thus obtaining the modified LiFePO4 positive electrode material. The intrinsic conductivity of Li3V2(PO4)3 is improved by doping iron ions; the electron conductivity of Li3V2 (PO4) 3 is improved by oxide coating, the cost is low, and no pollution occurs; less harmful gas is emitted in the synthesis process; the electrochemical performance of the material is excellent.

Description

technical field [0001] The invention relates to a doped and coated co-modified lithium vanadium phosphate cathode material and a preparation method thereof, belonging to the field of electrochemical power sources. Background technique [0002] Lithium-ion batteries have become an ideal energy storage device in the 21st century due to their high operating voltage, high energy density, no memory effect, small self-discharge, long cycle life, and environmental friendliness. In recent years, lithium-ion batteries have been widely used in notebook computers, mobile phones, electronic products, etc., and will be further used in electric vehicles, electric bicycles, aerospace and other industries in the future. With the increasing application of lithium-ion batteries, the performance requirements of lithium-ion batteries in various fields are also getting higher and higher. [0003] As the main component of lithium-ion batteries, cathode materials account for the highest proportio...

AI Technical Summary

Problems solved by technology

At present, commercial lithium-ion batteries mainly use lithium cobalt oxide as the positive electrode material. It has the advantages of simple synthesis and stable performance. battery requirements

Although lithium manganese oxide is low in cost and environmentally friendly, its low capacity and poor high temperature performance lead to certain restrictions on its use

Compared with lithium cobalt oxide, the capacity and cycle performance of ternary materials have been improved, and the cost has also been reduced, but the compaction density is low, the conductivity is not as good as that of cobalt, and the production process is complicated. The current technology is not mature enough, so the current main focus In the low-end market, it needs to be mixed with cobalt in the high-end market

However, since Li 3 V 2 (PO 4 ) 3 VO in the structure 6 Octahedron and PO 4 The tetrahedrons are separated, reducing the Li 3 V 2 (PO 4 ) 3 The conductivity of the material; in addition, Li 3 V 2 (PO 4 ) 3 Li + The diffusion rate is low, and cycling at high voltage (4.8V) increases the capacity fading

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