On April 22, Nature Nanotechnology published an article titled “Injection of oxygen vacancies in the bulk lattice of layered cathodes”, reporting the latest results in the field of layered metal oxide achieved by a joint effort of Prof. Li-Min Liu from the School of Physics of Beihang University, Prof. Chongming Wang from the Pacific Northwest National Laboratory (PNNL) of USA, Prof. Yanfei Peng from the Beijing University of Technology, etc. Via experiments and theoretical calculation, it is found that the migration and activation of the oxide ion in layered cathode is much easier than currently realized.
With the high energy density, layered cathode materials are expected to replace the current commonly used cathode materials and achieve the breakthrough in designing high-capacity lithium-ion batteries. During operation of a rechargeable battery, except the reduction of transition metal cations, triggered oxide ions redox process also provides high-capacity to Lithium-rich layered cathode. However, this process is associated with a high cutoff voltage at which an anionic redox process is activated. Therefore, it may cause severe surface degradation, of which the degradation led by surface phase transition is a significant degradation mechanism. The research finds that it is easy for oxygen vacancies to migrate in the layered cathode materials. Nanovoid formation and lattice structure transformation start from the particle surface and gradually propagate towards the centre as the battery is cycled. The mechanism increases the understanding of the generation and migration rules of oxide ions in the layered cathode materials, which provides the research basis for optimizing the stability of the cathode materials for lithium-ion batteries.
Since joining the School of Physics of Beihang University in September 2017, Prof. Li-Min Liu have published a series of articles on the defect of metal oxides. As a corresponding author, he has published five papers in Nature sub-journals, one in Nature Nanotechnology, one in Nature Phonics and three in Nature Communications. In 2018, invited by Surface Science Reports, he wrote a review article titled “Excess electrons in reduced rutile and anatase TiO2” (Surf. Sci. Rep. 73, 58 (2018)).
The research article:
Reported by Liu Rui
Edited by Jia Aiping
Reviewed by Lu Guanghong
Translated by Zhao Yue