Fine-Tuned Synthesis for Reducing Residual Lithium in Ni-Rich Cathode Materials for Lithium-Ion Batteries

Incidentally generated residual lithium on the surface during the synthesis of Ni-rich cathode materials for lithium-ion batteries has been considered one of the most serious problems to be solved. In this work, a suitable condition for simple washing and post-heat treatment with additional lithium salt process for preparing LiNi 0.8 Co 0.1 Mn 0.1 O 2 is optimized through a systematic evaluation. By varying amount of additional lithium salt, the most appropriate input is found to be 5 wt % in terms of electrochemical performance, such as initial capacity, capacity retention, and rate capability. In addition, it is verified by several techniques that it has the ideal composition (lithium/transition metal = 1:1) and the stable structure of R 3̅ m . From electrochemical impedance spectroscopy, it is found that the good performance of the cell assembled using the optimized material is originated from lowering resistance between the cathode and the electrolyte.