Ternary precursor with controllable crystal structure, positive electrode material and preparation method of positive electrode material

Abstract

The invention discloses a ternary precursor with a controllable crystal structure, a positive electrode material and a preparation method of the positive electrode material. Specifically, a nickel-cobalt-manganese soluble salt, NaOH, concentrated ammonia water and a surfactant for oriented growth are separately formulated into solutions and then subjected to a coprecipitation reaction to obtain aternary precursor of an oriented grow structure; the precursor is mixed with a lithium source and then calcined at high temperature to obtain a ternary layered positive electrode material of an oriented grow precursor-like structure. The positive electrode material the crystal structure of which grows in a [003] direction is obtained by regulating the growth of the precursor, so that the order degree of internal structure growth is increased, the stability of internal structure growth is improved, cation mixing and Li+ diffusion resistance are reduced, and the Li+ diffusion coefficient is increased. The ternary precursor with the crystal structure controllable, the positive electrode material and the preparation method of the positive electrode material are applicable to lithium-ion powerbatteries. Compared with existing products, the ternary precursor and the positive electrode material have the advantages that the rate performance and cycle stability of lithium-ion batteries are significantly improved.

Description

technical field [0001] The invention belongs to the field of lithium-ion battery materials, and in particular relates to a ternary precursor with an adjustable crystal structure, a positive electrode material and a preparation method thereof. Background technique [0002] With the increasing demand for energy worldwide and the continuous attention to environmental issues, ternary layered cathode materials have the advantages of high energy density, wide operating temperature and operating voltage range, no memory effect, and long cycle life. It has been widely used in digital products and electric tools, and is considered to be an ideal power source for the next generation of electric vehicles. [0003] NCM materials have a high specific capacity, and the energy density of a single cell is greatly improved compared with LFP and LMO batteries. In recent years, the research and industrialization of NCM power batteries have made great progress in Japan and South Korea. The ind...

AI Technical Summary

Problems solved by technology

The influence of the three elements on the electrochemical properties of materials is also different. Generally speaking, Co can effectively stabilize the layered structure and inhibit cation mixing, improve electronic conductivity and improve cycle performance; but the increase of the proportion of Co makes the unit cell parameter a And c decreases and c / a increases, resulting in a decrease in capacity; Mn can reduce costs and improve structural stability and safety, but too high Mn will reduce the gram capacity of the material, and it is easy to produce spinel phase and destroy the material The layered structure; the presence of Ni increases the unit cell parameters c and a and reduces c / a, which helps to improve the capacity, but if the Ni content is too high, it will interact with Li + The rate and cycle performance will deteriorate due to the mixing effect, and the pH value of the high-nickel material is too high to affect the actual use

[0006] (1) The cation mixing effect and the change of the surface microstructure of the material during the first charging process cause the first charge and discharge efficiency of NCM materials to be low (generally < 90%);

[0007] (2) The gas production of NCM batteries is serious, the safety is relatively prominent, and the high-temperature storage and cycle performance need to be improved;

[0008] (3) The diffusion coefficient and electronic conductivity of NCM materials are low, which makes the rate performance not very ideal;

[0009] (4) The secondary particles of NCM materials will be broken under higher compaction, which limits the further improvement of pole piece compaction and battery energy density

[0010] In response to the above problems, in order to improve the performance of related aspects of materials (such as thermal stability, rate performance, etc.), the industry widely adopts doping and coating modification, but often only one aspect of performance can be improved, and it is often accompanied by other aspects. performance degradation

Images