Improvement of Electrochemical Properties of Natural Graphite Anode Materials with an Ovoid Morphology by AlPO[sub 4] Coating

-coated natural graphite was prepared by mixing precipitated nanoparticles with natural graphite (NG) powders that had an ovoid morphology in water, followed by vacuum-drying at for . This simple coating method did not require any further heat-treatment above , which is an essential process for the sol-gel driven coating methods ( and ). The electrochemical properties of the -coated NG were compared with bare and pitch-coated samples and are reported. Impedance analysis revealed that, although the value of the surface film impedance of the -coated sample was 2.4 times larger than the bare NG, its charge-transfer (CT) impedance was 7.5 times smaller than the bare NG. Consequently, we believe that CT was a critical factor that affected the cycle life performance of the sample.