Shale-like Co3O4 for high performance lithium/sodium ion batteries

Abstract

In recent years, metal-organic compounds have been considered as ideal sacrificial templates to obtain transition metal oxides for electrochemical applications due to their diverse structures and tunable properties. In this work, a new kind of cobalt-based metal organic compound with a layered structure was designed and prepared, which was then transformed into ultrafine cobalt oxide (Co₃O₄) nanocrystallites via a facile annealing treatment. The obtained Co₃O₄ nanocrystallites further assembled into a hierarchical shale-like structure, donating extremely short ion diffusion pathway and rich porosity to the materials. The special structure largely alleviated the problems of Co₃O₄ such as inferior intrinsic electrical conductivity, poor ion transport kinetics and large volume changes during the redox reactions. When evaluated as anode materials for lithium-ion batteries, the shale-like Co₃O₄ (S-Co₃O₄) exhibited superior lithium storage properties with a high capacity of 1045.3 mA h g⁻¹ after 100 cycles at 200 mA g⁻¹ and good rate capabilities up to 10 A g⁻¹. Moreover, the S-Co₃O₄ showed decent electrochemical performance in sodium-ion batteries due to the above-mentioned comprehensive merits (380 and 153.8 mA h g⁻¹ at 50 and 5000 mA g⁻¹, respectively).