Nanosized LiMn₂O₄ powders prepared by flame spray pyrolysis from aqueous solution

LiMn₂O₄ powders have been directly prepared by flame spray pyrolysis from an aqueous spray solution of the metal salts. The powders prepared at a low fuel gas flow rate (3 L min^-1) comprise particles with a bimodal size distribution, i.e., submicron- and nanometer-sized particles, and have crystal structures of LiMn₂O₄ and Mn₃O₄ phases. However, the powders prepared at a high fuel gas flow rate (5 L min^-1) comprise nanometer-sized particles and have pure crystal structure of LiMn₂O₄ phase. The powders comprising nanosized particles are well crystallized, and the particles have a polyhedral structure. The mean particle size of these powders is 27 nm. The powders prepared directly by flame spray pyrolysis comprise nanosized particles and have the pure crystal structure of LiMn₂O₄, irrespective of the amount of excess lithium in the precursor solution. The initial discharge capacities of these powders increase from 91 to 112 mAh g ^-1 when the amount of excess lithium is increased from 0% to 30% of the stoichiometric amount. The optimum amount of excess lithium required to prepare LiMn₂O₄ powders with nanosized particles and the maximum possible initial discharge capacity is 10%.