A system and method thereof are provided for multi-stage processing of one or more precursor compounds into a battery material. The system includes a mist generator, a drying chamber, one or more gas-solid separators, and one or more in-line reaction modules comprised of one or more gas-solid feeders, one or more gas-solid separators, and one or more reactors. Various gas-solid mixtures are formed within the internal plenums of the drying chamber, the gas-solid feeders, and the reactors. In addition, heated air or gas is served as the energy source within the processing system and as the gas source for forming the gas-solid mixtures to facilitate reaction rate and uniformity of the reactions therein. Precursor compounds are continuously delivered into the processing system and processed in-line through the internal plenums of the drying chamber and the reaction modules into final reaction particles useful as a battery material.