LiCoO₂ Nanoplates with Exposed (001) Planes and High Rate Capability for Lithium-Ion Batteries

We report the synthesis of near-uniform LiCoO₂ nanoplates by a two-step approach in which β-Co(OH)₂ nanoplates are synthesized by co-precipitation and then transformed into LiCoO₂ nanoplates by solid state reaction at 750 ℃ for 3 hours. Characterization by high-resolution transmission electron microscopy (HRTEM) and electron diffraction (ED) reveal that the as-prepared LiCoO₂ nanoplates are covered with many cracks and have exposed (001) planes. The electrochemical performance of the LiCoO₂ nanoplates was investigated by galvanostatic tests. The capacity of LiCoO₂ nanoplates stabilized at 123 mA·h/g at a rate of 100 mA/g and 113 mA·h/g at a rate of 1000 mA/g after 100 cycles. The excellent rate capability of the LiCoO₂ nanoplates results from cracks which are perpendicular to the (001) plane and favor fast Li+ transportation. In addition, compared with other methods of synthesis of LiCoO₂ the time of the solid reaction state is significantly shorter even at relatively low temperatures, which means the energy consumption in preparing LiCoO₂ is greatly decreased. The controllable synthesis of LiCoO₂ nanoplates with exposed (001) plane paves an effective way to develop layered cathode materials with high rate capabilities for use in Li-ion batteries.