Synthesis of dual-modified cathode materials for high-energy lithium-ion batteries

by:CTECHi     2021-07-04

Nickel-rich ternary cathode material, due to its advantages of high reversible capacity and low cost, is considered to be one of the most ideal cathode materials for next-generation high-energy density lithium-ion power batteries. However, problems such as poor interface stability and deterioration of the internal structure of the secondary particles have severely hindered the large-scale application of this type of cathode material.

Recently, Li Lingjun, associate professor of Changsha University of Science and Technology, and Zhang Qiaobao of Xiamen University, Lu Jun of Argonne National Laboratory, University of Nebraska Lincoln, Brookhaven The National Laboratory and other professors and teams at home and abroad have completed a work, guided by first-principles calculations, and simultaneously synthesized a 'dual modified' nickel-rich ternary cathode material doped with titanium and coated with lanthanum nickel lithium oxide. . This simple and efficient synthesis method is expected to greatly reduce the production threshold of high-performance nickel-rich ternary materials. The results were recently published in the international journal 'Advanced Functional Materials'.

The team started from analyzing the migration barriers of titanium and lanthanum on the surface of nickel-rich ternary materials, and found that the state where titanium is incorporated into the bulk and lanthanum escapes to the surface is the system energy The lowest state is the steady state. According to the theoretical calculation results, they rationally designed and synthesized the 'dual modified' nickel-rich ternary material. The material exhibits good thermal stability, structural stability and excellent electrochemical performance. After 150 cycles of high temperature at 60 degrees Celsius, the capacity retention rate of the dual-modified material is nearly twice that of the pure phase nickel-rich material. After using full-field transmission X-ray microscopy to visualize the positive electrode material before and after the cycle, the team proved that the “dual modification” can inhibit the generation of micro-cracks in the secondary particles of the positive electrode material and the growth of micro-cracks during the cycle. The uneven distribution of Ni3+ among the secondary particles of the nickel-rich material is effectively suppressed, thereby significantly improving the structural stability of the secondary particles of the material.

This discovery provides new ideas and theoretical guidance for the development and application of nickel-rich ternary materials, and contributes to the development of high-energy density lithium-ion power batteries.

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