Strategies for synthesizing conductive spinel cobalt oxide nanoparticles for energy storage applications batteries and energy storage

Co3O4 spinel type nanoparticles (5-10 nm) were synthesized by oxidizing precipitation in various basic solutions. The materials prepared in lithium-containing hydroxide solutions exhibit high electronic conductivity (higher than 10−2 S.cm−1 at room temperature), which can be increased (up to 3 S.cm−1) by electrochemical oxidation. This high conductivity is due to the presence of Co4+ ions in the octahedral framework of the spinel structure, which entails electronic delocalization. In addition to high conductivity, the obtained powder exhibits a high surface area (around 200 m2.g−1), which should be suitable for applications in electrodes: as conductive additive in the positive electrode of alkaline Ni-MH cells, or directly as electrode material in hybrid C/metal oxide supercapacitors