Identification of Surface Impurities on LiFePO[sub 4] Particles Prepared by a Hydrothermal Process

was synthesized by a hydrothermal process at . The particle size of the was . The hydrothermally synthesized exhibited a discharge capacity of at the potential of vs . Transmission electron microscopy revealed the formation of an amorphous layer on the particle during the hydrothermal process. This amorphous layer was crystallized by a heat-treatment at in an argon atmosphere. The was generated on the particle surface during the annealing process. Two plateaus at 3.5 and were observed in discharge curve for the annealed . The plateau at was correlated with -ion insertion into . Addition of ascorbic acid as a reducing agent to the precursor was useful in prohibiting the conversion of to during the hydrothermal process and the generation of during the annealing process. It was found that a trace amount of carbonaceous material was formed on the particle due to the decomposition of ascorbic acid. The hydrothermally synthesized followed by annealing at exhibited a discharge capacity of .