Abstract
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.
Highlights
Cobalt oxide that has high energy density, is the next-generation candidate as the anode material for Lithium-ion batteries (LIBs)
These amine groups on the PAH-modified Co3O4 NFs have the electrostatic attraction with the epoxy groups of graphene oxide (GO), and ring opening reaction between the PAH-modified Co3O4 NFs and GO occurs
Co3O4 converts to the Co metal nanograins dispersed in Li2O matrix after conversion reaction with 8 moles of Li+ per one mole of Co3O4
Summary
Cobalt oxide that has high energy density, is the next-generation candidate as the anode material for LIBs. 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. 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. Cobalt oxide (Co3O4) is an emerging candidate because of its high theoretical capacity (890 mAh g−1), based on the conversion reaction. Practical use of Co3O4 has been frustrated by the following main challenges: large volume changes of Co3O4 (~300%) upon cycling, low electrical conductivity of Co3O4, and formation of insulative Li2O matrix due to the conversion reaction. We suggested desirable design for hybrid nanocomposite architecture of Co3O4 and graphene
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