Microemulsion-assisted synthesis of nanosized Li-Mn-O spinel cathodes for high-rate lithium-ion batteries

Li1.16Mn1.84O4 nanoparticles (50-90 nm) with cubic spinel structure are synthesized by combining a microemulsion process to produce ultrafine Mn(OH)2 nanocrystals (3-8 nm) with a solid-state lithiation step. The nanostructured lithium-rich Li1.16Mn1.84O4 shows stable cycling performance and superior rate capabilities as compared with the corresponding bulk material, for example, the nano-sized Li1.16Mn1.84O4 electrode shows stable reversible capacities of 74 mAhg-1 during the 1000th cycle at a high rate of 40 C between 3.0 and 4.5 V. In addition, Li1.16Mn1.84O4 nanoparticles also show high Li storage properties over an enlarged voltage window of 2.0-4.5 V with high capacities and stable cyclability, for example, delivering discharge capacities of 209 and 114 mAhg-1 at rates of 1 and 20 C, respectively.