Facile synthesis of well-shaped spinel LiNi0.5Mn1.5O4 nanoparticles as cathode materials for lithium ion batteries

Spinel LiNi0.5Mn1.5O4 (LNMO) nanoparticles with well-defined polyhedral shapes and mean sizes of ca. 200 nm have been synthesized via a solid-state route using alpha-MnO2 nanowires as reaction precursors. A structural reorganization is believed to be responsible for the morphology evolution from tetragonal alpha-MnO2 nanowires to spinel LNMO nanoparticles. Galvanostatic charge-discharge measurements indicate the LNMO nanoparticles exhibit a high initial discharge capacity of 129 mA h g(-1) with an 88% capacity retention over 100 cycles at 1C (147 mA h g(-1)), superior to those of LNMO nanorod counterparts (116 mA h g(-1)). The superior electrochemical performance of LNMO nanoparticles can be ascribed to their narrow particle size distribution, less particle aggregation, intimate interparticle contact, increased electrical conductivity and lithium ion insertion-extraction kinetics due to the existence of oxygen deficiency and exposed {111} crystal facets.