Microemulsion‐Assisted Synthesis of Nanosized LiMnO 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 mAh g−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 mAh g−1 at rates of 1 and 20 C, respectively.