Low temperature synthesis of nanocrystalline Li₄Mn₅O₁₂ by a hydrothermal method

A mild hydrothermal method using Li-birnessite (Li_xMnO₂·nH₂O) ultrafine fiber as the precursor has been adopted to prepare Li₄Mn₅O₁₂, which is of interest as an electrode material for 3 V rechargeable lithium ion batteries. X-ray diffraction data reveal that the obtained powders have a pure spinel structure with a lattice constant of 8.135 Å. The scanning electron microscopy image of the obtained powders shows the particles are cubic-shaped whose average size is about 40-50 nm. The results from inductively coupled plasma-atomic emission spectroscope and wet chemical analysis indicate that a Li/Mn ratio of 0.796, and an average valence of 3.96 of Mn ion have been achieved in the as-prepared products. The thermogravimetric and differential thermal analysis data also agree with the previous reports on Li₄Mn₅O₁₂, suggesting that near stoichiometry of Li₄Mn₅O₁₂ has been synthesized by this procedure at the rather low temperature 110°C.