Porous Co₃O₄ nanofibers surface-modified by reduced graphene oxide as a durable, high-rate anode for lithium ion battery

Here we report our findings in synthesis and characterization of porous Co₃O₄ nanofibers coated with a surface-modification layer, reduced graphene oxide. The unique porous Co₃O₄@rGO architecture enables efficient stress relaxation and fast Li⁺ ions and electron transport during discharge/charge cycling. When tested in a half cell, the Co₃O₄@rGO electrodes display high Coulombic efficiency, enhanced cyclic stability, and high rate capability (∼900 mAh/g at 1A/g, and ∼600 mAh/g at 5 A/g). The high capacity is contributed by a stable capacity yielded from reversible conversion reactions above 0.8 V vs. Li/Li⁺, and a increasing capacity induced by the electrolyte decomposition and interfacial storage between 0.8 0.01 V during discahrge. A full cell constructed from a Co₃O₄@rGO anode and a LiMn₂O₄ cathode delivers good capacity retention with operation voltage of ∼2.0 V. These performances are better than those of other full cells using alloy or metal oxide anodes. Our work is a preliminary attempt for practicality of high capacity metal oxide anodes in Li-ion batteries used for the electronic devices.