NOVELTY - Method comprises: providing a first precursor; providing a second precursor; and reacting the first precursor and the second precursor to form reaction product particles comprising an electrode material, where the average particle size of the reaction product particles is 500 nm or less and at least 50% of the reaction product particles have a composition that is substantially uniform throughout an individual reaction product particle.    USE - The method is useful for forming reaction product particles comprising electrode material (which is lithium-based compound, preferably lithium iron phosphate), where the material is useful: as electrode composition for an electrode (all claimed). The reaction product particles are useful for energy storage, energy conversion, and electrochemical applications such as batteries or fuel cells.    ADVANTAGE - In the method, at least 70% of the reaction product particles: have a composition that is substantially uniform throughout an individual reaction product particle (i.e. the individual particles are substantially free of regions rich in iron phosphate, lithium, and/or other byproducts or precursor materials); and are substantially free of precursor material. The method substantially improves the electrochemical properties of the reaction product particles (having small particle size and/or high surface areas), including increased capacity, improved thermal stability, and extended charge/discharge cycling lifetimes (e.g. the number of charging/discharging cycles without degeneration). The reaction product particles reduce the amount of irreversible specific charge within a battery. The smaller sizes of the particles enhance lithium iron insertion and/or extraction during charge/discharge cycling, and improve safety. The method is repeatable, scaleable, and improves the consistency, manufacturability, and cost of battery materials incorporating the lithium-based compounds. The method provides a rapid and more direct process for forming reaction product particles. The method has the ability to control the morphology of materials at various stages during the fabrication process.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) an electrode composition comprising the reaction product particles comprising an electrode material; and    (2) a device comprising the electrode composition.