Up-scalable solution synthesis of phosphate-based composite electrodes: spray-drying with addition of solid carbon into the solution

Since the success story of lithium iron phosphate, other phosphate-based compounds have attracted a lot of interest as promising candidates for positive electrodes in lithium-ion or sodium-ion batteries. Their electronic conductivity usually has to be improved through the preparation of composite powders ensuring intimate contact between the active material and conductive carbon. This can be achieved by the postsynthesis mixing of the phosphate particles with carbon or a carbon precursor. However, creating composites with the carbon source at the synthesis stage is often more efficient, either by reduction of a carbon precursor (sucrose, citric acid, etc) or by addition of conductive carbon (carbon black or carbon nanotubes) in the reactant mixture/solution.