We report a facile synthesis of a novel cobalt oxide (Co₃O₄) hierarchical nanostructure, in which crystalline core-amorphous shell Co₃O₄ nanoparticles with a bimodal size distribution are uniformly dispersed on ultrathin Co₃O₄ nanosheets. When tested as anode materials for lithium ion batteries, the as-prepared Co₃O₄ hierarchical electrodes delivered high lithium storage properties comparing to the other Co₃O₄ nanostructures, including a high reversible capacity of 1053.1 mAhg⁻¹ after 50 cycles at a current density of 0.2 C (1 C = 890 mAg⁻¹), good cycling stability and rate capability.

Co₉S₈ nanoparticles encapsulated in nitrogen-doped mesoporous carbon networks have been synthesized by annealing a cobalt containing metal organic framework with sulfur powders. The products exhibit excellent lithium storage properties.