Effects of precursor, synthesis time and synthesis temperature on the physical and electrochemical properties of Li(Ni1−x−yCoxMny)O2 cathode materials

Abstract

The effects of the synthesis temperature, the synthesis time and the nature of the transition-metal hydroxide precursors on the physical and electrochemical properties of Li(Ni1−x−yCoxMny)O2 synthesized using solid-state reactions are studied. Higher synthesis temperature results in larger primary and secondary particle sizes, a lower tap density and a broader secondary particle size distribution. Increase in reaction time improves the crystallinity and the cyclability. A smaller primary particle size of the precursor leads to a larger primary particle size of Li(Ni1−x−yCoxMny)O2. Li(Ni1−x−yCoxMny)O2 with a better crystallinity, a well-defined layered structure and a better cation ordering exhibits a higher capacity, a better cycling performance and rate capability. The optimized synthesis conditions for precursors NCMOH111-α and NCMOH424-a is 950 °C for 12 h and 950 °C for 9 h, respectively. NCM111-α-950-12h delivers a discharge capacity of 165.5 mAh g−1 during the initial cycle at a rate of 0.1C with a columbic efficiency of 87%, a 3C rate capability of 91.25% and a 1C capacity retention rate of 98.25% after 40 cycles.