Preparation of LiNi0.5Mn1.5O4 cathode materials by using different-sized Mn3O4 nanocrystals as precursors

High-voltage LiNi0.5Mn1.5O4 with a spinel structure is considered as important cathode materials for high-energy density Li-ion batteries (LIBs). In this study, we investigate the size, structure, and the electrochemical performance of LiNi0.5Mn1.5O4 electrodes prepared by using two different-sized Mn3O4 nanocrystal precursors under different calcination conditions. As the calcination temperature rises, the particle sizes of the acquired LiNi0.5Mn1.5O4 cathode materials can vary from ~ 100 nm to ~ 1 µm, and the morphology changes from nano round shape to truncated octahedral shape. The content of Mn3+ is closely related to the calcination temperature and is affected by the size of Mn precursor. It is found that the LiNi0.5Mn1.5O4 sample prepared by using 50-nm-sized Mn3O4 nanocrystals under a calcination temperature of 800 C exhibits good cycling performance with a capacity retention ratio of 96.1% at 1 C after 200 cycles, while the LiNi0.5Mn1.5O4 sample prepared by using 7-nm-sized Mn3O4 nanocrystals under a calcination temperature of 800 °C shows an excellent rate performance with a capacity retention ratio of 98% after 500 cycles at 10 C. The results show that the size of Mn3O4 precursor is an important parameter that governs the final size and electrochemical performances of LiNi0.5Mn1.5O4 cathode materials.