Single‐Crystalline LiMn2O4 Nanotubes Synthesized Via Template‐Engaged Reaction as Cathodes for High‐Power Lithium Ion Batteries

Single‐crystalline nanotubes of spinel LiMn₂O₄ with a diameter of about 600 nm, a wall thickness of about 200 nm and a length of 1–4 μm have been synthesized via a template‐engaged reaction using β‐MnO₂ nanotubes as a self‐sacrifice template. In this fabrication, a minimal structural reorganization can be responsible for the chemical transformation from [001]‐oriented β‐MnO₂ template to [110]‐oriented LiMn₂O₄. Galvanostatic charge/discharge measurements indicate that the nanotubes exhibit superior high‐rate capabilities and good cycling stability. About 70% of its initial capacity can be retained after 1500 cycles at 5 C rate. Importantly, the tubular nanostructures and the single‐crystalline nature of the most LiMn₂O₄ nanotubes are also well preserved after prolonged charge/discharge cycling at a relatively high current density, indicating good structural stability of the single‐crystalline nanotubes during lithium intercalation/deintercalation process. As is confirmed from Raman spectra analyses, no evident microstructural changes occur upon long‐term cycling. These results reveal that single‐crystalline nanotubes of LiMn₂O₄ will be one of the most promising cathode materials for high‐power lithium ion batteries.