Effect of aluminum fluoride coating on the electrochemical and thermal properties of 0.5Li2MnO3·0.5LiNi0.5Co0.2Mn0.3O2 composite material

The positive effect of AlF3 (Al–F) coating on the over-lithiated transition metal oxide with a composition of 0.5Li2MnO3·0.5LiNi0.5Co0.2Mn0.3O2 has been investigated to address its potential use in lithium ion batteries. On the basis of various structural and electrochemical characterizations, we elucidate a correlation between surface structure and its electrochemical performance. After the controlled coating with AlF3 (Al–F), we observed notable improvements on cyclic performance and rate capability as well as thermal stability. We found that uniformly introduced AlF3 (Al–F) not only preserves the electrochemical kinetics at the surface of the oxide but also stabilizes its surface as a protective layer against electrolyte oxidation during the high voltage charging. Such improvements will provide a further progress on the development of high-capacity cathode materials fulfilled with the stringent safety requirements.

► We propose the concept of surface modification with AlF3 (Al–F) on the 0.5Li2MnO3·0.5LiNi0.5Co0.2Mn0.3O2.
► The positive effects of Al–F coating is demonstrated based on various structural and electrochemical analyses.
► By the coating of Al–F, the electrochemical and thermal properties of composite electrode were notably enhanced.