Electrochemical behavior of Mn-based Li-rich cathode material Li1.15Ni0.17Co0.11Mn0.57O2 fluorinated by NH4F

Abstract

Mn-based Li-rich cathode material is considered as the most potential one for high energy density secondary lithium ion batteries. Herein, we demonstrate the improved electrochemical performance of Li1.15Ni0.17Co0.11Mn0.57O2 material via surface fluorination by NH4F at various conditions. It is found that the initial coulombic efficiency, discharge capacity and cycling stability of the Li-rich material are significantly improved after surface fluorination, which could be attributed to the optimized wettability between the electrode material and electrolyte and the reduced irreversible lattice oxygen loss during cycling. The Li1.15Ni0.17Co0.11Mn0.57O2 fluorinated at 400 °C exhibits high reversible discharge capacity of 262.0 mAh g−1 as the initial coulombic efficiency is 91.2%, and favorable cycle performance as the capacity retention is 97.1% after 50 cycles at 0.1C.