Optimizing conditions and improved electrochemical performance of layered LiNi_1/3Co_1/3Mn_1/3O₂ cathode material for Li-ion batteries

Herein, we have explored performance of layered LiNi_1/3Co_1/3Mn_1/3O₂ (NCM111) cathode material for Li ion battery applications, prepared by different preparation strategies namely co-precipitated mixed hydroxide and solid state high temperature approach combined with high-temperature calcination. The effect of crystal structure and morphology of the obtained materials were characterized by means of X-ray diffraction and scanning electron microscopy. X-ray analysis reveals that the observed lattice parameter ratio c/a is greater than 4.89 for materials with different approaches, which indicates the formation of hexagonal layered α-NaFeO₂ structure. The electrochemical properties of the materials were thoroughly characterized by means of charge–discharge experiments and electrochemical impedance spectroscopy. The direct solid state synthesized NCM111 material exhibits a low retention and discharge capacity of 60 mAh g⁻¹ at the end of 50 cycles with high irreversible capacity during cycling. The present studies have shown that the importance of material synthesis route and its sintering process, prepared at 900 °C for 8 h results low cation mixing between Li and metal ions layer in NCM111 lattice compared to other sintered samples, resulting in superior electrochemical performance. The reversible capacity of 175 mAh g⁻¹ is noticed at C/10 rate within the voltage window of 2.5–4.4 V for 900 °C treated sample. Even at C/3 rate, a stable high reversible capacity of 145 mAh g⁻¹ is obtained with high capacity retention of 95%. The Rietveld and EIS spectroscopic analysis conforms the existence stable layered structure and electrode, interface for NCM11 approached through co-precipitation.