Synthesis and Electrode Properties of Nanocrystalline Lithium Copper Iron Oxide Cathodes

Lithium copper iron oxides ( Li x Cu 1 − y Fe y O z ) have been synthesized by a solution-based procedure involving the oxidation of a mixture consisting of Fe 2 + and Cu 2 + ions with the oxidizing agent Li 2 O 2 in presence of LiOH ⋅ H 2 O . The samples before and after heat-treatment at various temperatures (200-800°C) have been characterized by X-ray diffraction, transmission electron microscopy (TEM), and atomic absorption spectroscopy. The composition of the product Li x Cu 1 − y Fe y O z is controlled by the concentration of the reactants. TEM data reveal the 200°C samples to be nanocrystalline although X-ray diffraction does not show any discernible reflections. The 200-300°C heated samples show high initial capacity of around 300 mAh/g in the voltage range of 1.5 to 4.3 V. With optimized compositions, a reversible capacity of around 230 mAh/g could be achieved with good cyclability.