Li Lingjun, an associate professor at the School of Materials Science and Engineering of Changsha University of Technology, and Zhang Qiaobao, an assistant professor at Xiamen University, Lu Jun, a professor at Argonne National Laboratory, as well as researchers and teams at home and abroad, including Lincoln University of Nebraska and Brookhaven National Laboratory, have synthesized dual modified cathode materials for high-energy lithium-ion batteries.

The research results were published in the latest issue of Advanced Functional Materials, an important international academic journal in the field of material chemistry, with Changsha University of Technology as the first unit. The first author is Yang Huiping, a postgraduate student of Changsha University of Technology, and Li Ling as the first correspondent.

Lithium-ion batteries have many advantages, such as high reversible capacity, high working potential, long cycle life and low self-discharge. They have been widely used in various portable devices, and have been gradually promoted and applied in the field of energy storage and electric vehicles.

“Among the commercial cathode materials, nickel-rich ternary materials with layered structure have high energy density (280 Whkg-1 specific energy of single cell) and low cost, which are more and more popular in the market. However, there are still some problems in nickel-rich ternary cathode materials, such as poor interfacial stability and deterioration of internal structure of secondary particles, which seriously hinder its large-scale application. Li Lingjun said.

For this reason, the research team took high-capacity nickel-rich cathode materials for lithium-ion batteries as the research object. After three years’analysis of the migration barriers of titanium and lanthanum on the surface of nickel-rich ternary materials, it was found that the state in which titanium doped bulk phase and lanthanum enriched on the surface was the lowest energy of the system, i.e. the stable state. According to the theoretical calculation results, they reasonably designed and synthesized the double modified nickel-rich ternary materials doped with titanium and coated with lanthanum, nickel and lithium oxide.

Li Lingjun introduced that the material exhibited good thermal stability, structural stability and excellent electrochemical properties. “After 150 cycles at 60 degrees Celsius, the capacity retention rate of the double modified material is nearly twice as high as that of the pure phase nickel-rich material, which can effectively inhibit the nano-scale structure degradation of the surface of the nickel-rich material during the cycles, thereby enhancing the surface stability of the nickel-rich material.”

In addition, the research team used full-field transmission X-ray microscopy to visualize the cathode materials before and after cycling. The results showed that the double modification inhibited the generation and propagation of microcracks in the secondary particles of the cathode materials during cycling. The inhomogeneous distribution of Ni3+ between the secondary particles of nickel-rich materials was inhibited after cycling, and the structural stability of the secondary particles of the materials was obvious. Upgrade. The research has been supported by the National Natural Science Foundation of China, the National Key Research and Development Program, the Outstanding Innovative Youth Training Program of Changsha City and the Department of Energy of the United States.