Synthesis, characterization, and Li-electrochemical performance of highly porous Co₃O₄ powders

Abstract

Oxidative precipitation in an aqueous medium of highly self-compacted crystallized Co₃O₄ dense nanoparticles (4-5 nm) leads to the formation of porous micrometric agglomerates exhibiting a well-defined porosity distribution. Postannealing of these powders induces drastic reorganizations first because of the fast removal of trapped water and then because of the particles sintering, resulting in larger inter-particle voids. Electrochemical behavior of this nanometric material precipitated at moderate temperature is found to be extremely dependent on the way the mixing with the SP conducting carbon is performed; the better performances being obtained by a soft mixing in an organic solvent. This textural effect provides a stable capacity over the first cycles (800 mA·h/g) and reveals a first cycle capacity loss of the same extent as for bulk Co₃O₄, implying that the nanotexturation undergone by bulk oxide particles during their first formatting cycle is not responsible for the corresponding initial loss. Through chemical analysis of the electrolyte we found that the long-term capacity fading of our materials can be mainly attributed to the dissolution of the active material within the organic electrolyte.