Synthesis of Li[Ni1/3Co1/3Mn1/3]O2-zFz Synthesized via Coprecipitation

초록

Li[Ni1/3Co1/3Mn1/3]O2 comprises very promising positive electrode materials for high energy and high power lithium-ion batteries. In attempts to increase the reversible capacity of the cathode material, the upper cut-off voltage limit is getting higher. Such a high voltage limit led to obvious increase in the specific discharge capacity. However, Li[Ni1/3Co1/3Mn1/3]O2 has an unstable cycling performance when it cycles up to 4.6V. The origin of the capacity fading is mainly due to the decaying of electroactive Co ingredient as it was reported by Shaju et al. and Yoon et al. Metal oxide coated-LiCoO2 showed an enhanced capacity retention above the 4.6V charge-cutoff voltages comparing to bare LiCoO2. Another possible approach is to replace oxygen with other elements, such as F and S. Fluorine substitution for oxygen in lithium nickelate system was pretty effective to obtain a reduced impedance, lattice changes during cycling and cycling life. This paper focuses on the electrochemical properties of F-doped Li[Ni1/3Co1/3Mn1/3]O2-zFz at higher cut-off voltage limit (4.6V) and compares their performances with un-substituted Li[Ni1/3Co1/3Mn1/3]O2.