The Effect of Si Doping or/and Ti Coating on the Electrochemical Properties of Ni-Rich NCA (LiNi0.8Co0.15Al0.05O2) Cathode Material for Lithium-Ion Batteries

LiNixCoyAlzO2 (NCA) is one of the most promising candidates of cathode material for lithium ion batteries because of its high capacity, energy density, and low cost. However, Ni-rich NCA cathode materials suffer from side reaction (formation of lithium carbonate and hydrogen fluoride attack) between electrolyte and surface of electrode and irreversible phase transition leading to capacity fading and thermal instability. These problems could be improved by coating and doping of transition metal elements. Si doping contributes to stabilization of the unstable R-3m structure, and Ti coating is capable of prohibiting the direct physical contact of electrode with electrolyte. In this work, LiNi0.8Co0.15Al0.05O2 (NCA) cathode materials coated or/and doped by Ti and Si elements were fabricated by co-precipitation method using the ball-milling. The crystal structure, morphology and electrochemical properties are investigated using X-ray diffraction (XRD), scanning electron microscopy (FE-SEM), transmission electron microscopy (FE-TEM), and WBCS3000 (WonA tech Co., Ltd.). The EIS and charge/discharge results of Si doped and Ti coated NCA exhibited the lowest resistance value (147.19 Ω) and capacity retentions of 88% after 100 cycles at 0.5 C.