Effect of precursor structure transformation on synthesis and performance of LiNi0.5Co0.2Mn0.3O2 cathode material

The precursor has great influences on electrochemical performance of LiNi 1-x-y Co x Mn y O 2 cathode materials. However, the effect of precursor structure transformation on the synthesis and electrochemical performance of LiNi 1-x-y Co x Mn y O 2 is rarely mentioned. In this paper, Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 and different-temperature-preheated Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 were synthesized to prepare LiNi 0.5 Co 0.2 Mn 0.3 O 2 . The results show that Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 precursor transform into spinel-type solid solution (Ni 0.5 Co 0.2 Mn 0.3 ) 3 O 4 after preheating, and the contents of Ni 3+ , Co 3+ and Mn 4+ increase significantly. Comparative analyses reveal that the precursor structure change has no obvious effects on the crystal structure and surface morphology of the prepared LiNi 0.5 Co 0.2 Mn 0.3 O 2 . But the preheated precursors can reduce the undesirable lithium loss due to lithium volatilization in the high-temperature sintering process, leading to excess lithium ions enter into transition metal ions layer. Lithium excess can affect the amount of Ni 3+ , lattice parameters and residual lithium compounds on the particle surface, which in turn lead to different electrochemical behaviors of the prepared LiNi 0.5 Co 0.2 Mn 0.3 O 2 . • Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 transform into spinel-type solid solution (Ni 0.5 Co 0.2 Mn 0.3 ) 3 O 4 after preheating, and the contents of Ni 3+ , Co 3+ and Mn 4+ increase significantly. • The preheated precursors show much better electrochemical performances than the un-preheated one, because the undesirable lithium loss due to lithium volatilization in the high-temperature sintering process is reduced. • Lithium excess can affect the amount of Ni 3+ , lattice parameters and residual lithium compounds on the particle surface.