Investigation on preparation and performance of spinel LiNi_0.5 Mn_1.5 O₄ with different microstructures for lithium-ion batteries

The high voltage spinel LiNi_0.5 Mn_1.5 O₄ is a promising cathode material in next generation of lithium ion batteries. In this study, LiNi_0.5 Mn_1.5 O₄ with various particle microstructures are prepared by controlling the microstructures of precursors. LiNi_0.5 Mn_1.5 O₄ spinel samples with solid, hollow and hierarchical microstructures are prepared with solid MnCO₃, hollow MnO₂ and hierarchical Mn₂O₃ as precursor, respectively. The homemade spinel materials are investigated and the results show that the content of Mn³⁺ and impurity phase differ much in these three spinel samples obtained under the same calcining and annealing conditions. It is revealed for the first time that an inhomogeneous migration of atoms may introduce Mn³⁺ and impurity phase in the spinel. The hierarchical microstructure with the primary particles interconnected is optimal for electrode materials because this microstructure has a higher conductivity between the interconnected primary particles and appropriate specific surface area. LiNi_0.5 Mn_1.5 O₄ in this microstructure has the best rate capability and also the best long-term cycling stability.