Preparation of LiMn₂O₄ powders via spray pyrolysis and fluidized bed hybrid system

A novel technique has been developed to directly produce fine ceramic powders from liquid solution using a spray pyrolysis and fluidized bed hybrid system. Using this technique, the preparation of lithium manganese oxides LiMn₂O₄, which are the most promising cathode materials for lithium-ion batteries, has been carried out for various superficial gas velocities U₀ = 0.30-0.91 m/s, static bed heights L_s = 50-150 mm, and medium particle sizes d_pm,g = 294-498 μm. The resulting powders had spherical nano-structured particles that comprised primary particles with a few tens of nanometer in size, and they exhibited a pure cubic spinel structure without any impurities in the XRD patterns. Moreover, the as-prepared powders showed better crystallinity and smaller specific surface area than those by conventional spray pyrolysis. The effects of process parameters on powder properties, such as specific surface area and crystallinity, were investigated for a wide range of superficial gas velocities and static bed heights. An as-prepared sample was used as cathode active materials for lithium-ion batteries and the cell performance has been investigated. Test experiments in the electrochemical cell Li/1M LiClO ₄ in PC/LiMn₂O₄ demonstrated that the sample prepared by the present technique was superior to that by the conventional spray pyrolysis and solid-state reaction method.