Rare-earth doping modified lithium ion battery ternary positive electrode material and preparation method thereof

Abstract

The invention relates to a rare-earth doping modified lithium ion battery ternary positive electrode material and a preparation method of the rare-earth doping modified lithium ion battery ternary positive electrode material. The chemical general formula of the material is as follows: LiNiaCo<1-a-b>MnbRxO2/M, wherein a is more than 0 and less than 1, b is more than 0 and less than 1, (1-a-b) is more than 0 and less than 1, x is more than 0.005 and less than 0.1, R is one or more of rare-earth lanthanum, cerium, praseodymium and samarium, and M is a composite cladding layer of oxide of aluminum, titanium or magnesium and carbon. The soluble metal nickel salt, cobalt salt, manganese salt and rare-earth compound are mixed to prepare a mixed salt solution, the mixed salt solution is reacted with a mixed alkaline solution prepared by mixing NaOH and ammonium hydroxide, after the reaction solution is filtered, washed and dried, the obtained product is uniformly mixed with lithium salt powder to be ball milled, then the mixture is calcined at the high temperature and coated with the composite cladding layer of the aluminum, titanium or magnesium oxide and carbon, and finally the calcined mixture is calcined at a constant temperature to obtain the rare-earth doping modified lithium ion battery ternary positive electrode material. After doping the rare earth, the metal oxide and carbon composite cladding layer, which are cheap and easy to obtain, are adopted, so that the cycling performance and the rate performance can be improved, and the charging-discharging efficiency of the material also can be improved.

Description

technical field [0001] The invention relates to the technical field of lithium ion battery cathode materials, in particular to a rare earth doped and modified lithium ion battery ternary cathode material and a preparation method thereof. Background technique [0002] Compared with other traditional secondary batteries, lithium-ion batteries have many advantages such as small size, high voltage, large specific capacity, and high energy density. Therefore, great progress has been made in the field of 3C electronics. The positive electrode material is an important part of lithium-ion batteries, and it is also the part with the highest cost ratio in lithium-ion batteries. [0003] As a new lithium-ion battery cathode material, the nickel-cobalt lithium manganate ternary cathode material combines the advantages of nickel, cobalt and manganese, and has a higher specific capacity than lithium cobalt oxide, lithium nickel oxide and lithium manganese oxide. , longer cycle life and b...

AI Technical Summary

Problems solved by technology

On the one hand, due to Ni 2+ with Li + The ionic radius of the ternary material is closer to the cation mixing phenomenon, which makes the material prone to lithium precipitation in the air, resulting in the deterioration of the electrochemical performance of the material; on the other hand, the contact of the ternary material with the electrolyte will dissolve part of the metal ions, In the process of repeated charging and discharging, the material collapses, which is not conducive to the improvement of cycle performance; on the other hand, the lithium ion diffusion coefficient and electronic conductivity of the material need to be further improved

[0004] In order to improve the safety of ternary materials, at present, improvements are mainly made in terms of doping and coating, but a single doping or coating cannot prepare ternary materials with excellent comprehensive properties.

Existing studies have used different methods to dope ternary materials with elements such as magnesium, zirconium, and aluminum. The results show that the rate performance of the doped material has improved, but the cycle performance has not changed much. Surface coatings such as titanium oxide and aluminum phosphate can improve the cycle performance and safety performance of the material, but will lead to a decrease in the specific capacity and rate of the material

There are also studies on the comprehensive modification of ternary materials by doping and coating, but the inactive coating layer will affect the surface conductivity of the material, resulting in a decrease in the rate performance of the battery.

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