Building stable high-voltage LiNi0·5Mn1·5O4 cathode material via a surface coating layer with CaF2

The spinel-structured LiNi 0·5 Mn 1·5 O 4 (LNMO) has attracted considerable attention in cathode material research due to its elevated energy density and high voltage. However, the practical application of LNMO is limited by issues such as surface structural instability and side reactions caused by electrolyte breakdown. To address these issues, this study constructed a CaF 2 coating layer on the surface of LNMO cathode material through wet chemical methods , investigated the protective mechanism and electrochemical performance of the CaF 2 coating layer on the cycling process of LNMO cathode material. Experimental findings indicate that an appropriate amount of CaF 2 coating does not modify the intrinsic structure of the material, effectively decreases side reactions with the electrolyte during the LNMO cycling process under high-voltage conditions, and significantly stabilizes the material structure and enhances capacity retention during high-rate cycling. Consequently, the material coated with 5 % CaF 2 demonstrates the best electrochemical performance, achieving a capacity retention of 92.7 % after 200 cycles at a 3C rate, compared to only 76.8 % for the bare material. This study provides some ideas for building stable high-voltage LNMO cathode material.