Effect of precursor and synthesis temperature on the structural and electrochemical properties of Li(Ni0.5Co0.2Mn0.3)O2

Abstract

Li(Ni0.5Co0.2Mn0.3)O2 layered materials were synthesized by solid-state reaction using Li2CO3 and three transition-metal hydroxide precursors of composition (Ni0.5Co0.2Mn0.3)(OH)2 (NMC Hydroxide) with different physical properties. Characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical testing, etc., the final Li(Ni0.5Co0.2Mn0.3)O2 products showed different physical and electrochemical properties depending on their synthesis temperatures and the properties of transition-metal hydroxide precursors were got. Higher reaction temperature results in bigger primary particle size (PPS) and broader size distribution. Precursor with smaller PPS results in larger PPS when synthesized at the same condition. The electrochemical performance is related to the physical properties of Li(Ni0.5Co0.2Mn0.3)O2. Better crystallized and cation ordered layered material has higher initial capacity while smaller and uniform PPS results in higher capacity retention rate. The Li(Ni0.5Co0.2Mn0.3)O2 synthesized at 880°C for 10h in atmosphere using (Ni0.5Co0.2Mn0.3)(OH)2 with smallest PPS size as the starting precursor showed the best overall electrochemical properties with a high discharge capacity over 171mAh/g with a capacity retention >96% after 50 cycles at 1C rate in a half battery and tap density about 2.7g/cm3.