Improved electrochemical performances of LiM0.05Co0.95O1.95F0.05 (M = Mg, Al, Zr) at high voltage

Abstract

Metal and F co-substituted LiM0.05Co0.95O1.95F0.05 (M = Mg, Al, Zr) cathode materials were successfully synthesized via a solid-state reaction. XRD measurements showed that cobalt and oxygen sites in LiCoO2 are successfully substituted for metal (Mg, Al, Zr) and fluorine, respectively. The co-substituted materials exhibited stable cycling performance, improved rate capability, and thermal stability compared to pristine LiCoO2. Furthermore, Co dissolution tests revealed that fluorine substitution stabilizes the cathode surface and thus suppresses Co dissolution. Among the materials, LiM0.05Co0.95O1.95F0.05 showed the best electrochemical and thermal properties.