US Patent 7371482 Lithium transition-metal phosphate powder for rechargeable batteries

Methods of manufacture and use of phosphates of transition metals are described as positive electrodes for secondary lithium batteries, including a process for the production of LiMPO4 with controlled size and morphology, M being FexCoyNizMnw, where 0≦x≦1,0≦y≦1, 0≦w≦1, and x+y+z+w=1. According to an exemplary embodiment, a process is described for the manufacture of LiFePO4 including the steps of providing an equimolar aqueous solution of Li1+, Fe3+ and PO43−, evaporating water from the solution to produce a solid mixture, decomposing the solid mixture at a temperature of below 500° C. to form a pure homogeneous Li and Fe phosphate precursor, and annealing the precursor at a temperature of less than 800° C. in a reducing atmosphere to produce the LiFePO4 powder. The obtained powders can have a particle size of less than 1 μm, and can provide superior electrochemical performance when mixed for an appropriate time with an electrically conductive powder.