Preparation method of lithium iron phosphate positive electrode material doped with nanometer titanium dioxide

Abstract

The invention provides a preparation method of lithium iron phosphate doped with nanometer titanium dioxide. The method comprises the following steps: preparing an iron phosphate precursor, mixing a lithium source, a carbon source and nano titanium dioxide, uniformly stirring, synthesizing by a high-temperature solid-phase method, and finally performing crushing to obtain a nano titanium dioxide doped lithium iron phosphate positive electrode material. Through comparison of compaction density, discharge capacity and cycle performance, it is verified that the lithium iron phosphate positive electrode material doped with the nanometer titanium dioxide can meet the requirements of high energy density and high cycle performance at the same time. According to the invention, the prepared lithium iron phosphate positive electrode material doped with the nanometer titanium dioxide can meet high compaction density and good conductivity at the same time, and is an excellent positive electrode material for preparing a lithium iron phosphate battery with high capacity and long cycle performance. The method has large-scale production conditions, and can provide high-quality raw materials for new energy battery manufacturers to produce high-capacity and long-life lithium iron phosphate batteries.

Description

technical field [0001] The invention belongs to the technical field of new energy materials, and relates to a method for preparing a high compacted density long-cycle lithium iron phosphate cathode material doped with nano-titanium dioxide. Background technique [0002] Due to its high theoretical capacity, high working voltage, appropriate energy density, small self-discharge, long cycle life, no memory effect, low price, good thermal stability, and environmental friendliness, lithium iron phosphate batteries are expected to replace high-cost batteries. The LiCoO2 battery has become a new generation of lithium-ion batteries. [0003] Compared with the ternary cathode material, lithium iron phosphate has a low tap density, and the prepared cell electrode has a low compaction density, which limits its energy density. As a result, the lithium iron phosphate industry was once suppressed by the ternary material cathode material. However, with the advantages of low cost, more en...

AI Technical Summary

Problems solved by technology

[0004] At present, the method of increasing the energy density of lithium iron phosphate is mostly to improve the compaction density, while the preparation of lithium iron phosphate cathode materials mostly adopts solid-phase synthesis method. The general process is to synthesize the precursor first, and then sinter it. Finally, the lithium iron phosphate positive electrode material with a certain particle size can be obtained by crushing. The smaller particle size can increase the compaction density, but the small particle size will increase the specific surface area, which is not conducive to the processing of the electrode. Therefore, the relationship between the equilibrium compaction density and the particle size is The key to preparing high energy density lithium iron phosphate

[0005] In terms of improving the cycle performance of lithium iron phosphate, most of the methods are to improve the conductivity and reduce the resistance by doping or coating carbon. However, due to the low density of carbon, adding carbon will lead to a decrease in the compaction density, which is not conducive to the preparation of high-density lithium iron phosphate. capacity lithium iron phosphate battery; another method is to dope metal ions in lithium iron phosphate to cause lattice defects inside lithium iron phosphate, thereby fundamentally improving the conductivity of the material

Compared with carbon doping or carbon coating, metal ion doping will not reduce the compaction density of the material, which is beneficial to improve the energy density and cycle performance of lithium iron phosphate batteries, but the improper doping ratio will cause lattice Large deformation is not conducive to the energy density and cycle performance of the battery

Images