Rational Design of 1-D Co₃O₄ Nanofibers@Low content Graphene Composite Anode for High Performance Li-Ion Batteries

Cobalt oxide that has high energy density, is the next-generation candidate as the anode material for LIBs. However, the practical use of Co₃O₄ as anode material has been hindered by limitations, especially, low electrical conductivity and pulverization from large volume change upon cycling. These features lead to hindrance to its electrochemical properties for lithium-ion batteries. To improve electrochemical properties, we synthesized one-dimensional (1-D) Co₃O₄ nanofibers (NFs) overed with reduced graphene oxide (rGO) sheets by electrostatic self-assembly (Co₃O₄ NFs@rGO). The flexible graphene oxide sheets not only prevent volume changes of active materials upon cycling as a clamping layer but also provide efficient electrical pathways by three-dimensional (3-D) network architecture. When applied as an anode for LIBs, the Co₃O₄ NFs@rGO exhibits superior electrochemical performance: (i) high reversible capacity (615 mAh g^-1 and 92% capacity retention after 400 cycles at 4.0 A g^-1) and (ii) excellent rate capability. Herein, we highlighted that the enhanced conversion reaction of the Co₃O₄ NFs@rGO is attributed to effective combination of 1-D nanostructure and low content of rGO (~3.5 wt%) in hybrid composite.