Synthesis and electrochemical performances of LiNi0.5Mn1.5O4 spinels with different surface orientations for lithium-ion batteries

LiNi0.5Mn1.5O4 materials with three different particle shapes, including octahedron composed of {111} surface, truncated octahedron with {111} and {100} surfaces, and chamfered polyhedron with {111}, {100}, and {110} surfaces, have been synthesized via a combined coprecipitation-hydrothermal method followed by three different calcination processes. The materials were characterized by XRD, FT-IR, SEM, EIS, XPS, and galvanostatic charge/discharge tests. All samples have a main disordered structure and similar primary particle size. Electrochemical results show the rate capability degrades in the order of chamfered polyhedron > truncated octahedron > octahedron, while the cycling stability deteriorates in the order of truncated octahedron > octahedron > chamfered polyhedron. It can be concluded that the particle shape, more specifically, surface orientations, exerts great influence on the electrochemical performance of LiNi0.5Mn1.5O4 material. Therefore, appropriate tailoring of surface orientations can simultaneously satisfy power capability and long cycle life. The particle shape design is of significance to LiNi0.5Mn1.5O4 material.