Coaxial Co3O4@polypyrrole core-shell nanowire arrays for high performance lithium ion batteries

Abstract

Coaxial Co3O4@polypyrrole (Co3O4@PPy) nanowire arrays have been successfully synthesized via a simple hydrothermal method and further a polymerization process. According to the composition and morphology characterization, it is found that a thin layer of amorphous PPy is uniformly coated on the surface of the Co3O4 nanowire. When directly used as an anode material for lithium-ion batteries, the Co3O4@PPy nanowire arrays electrode exhibits high reversible capacity, good rate capability, and improved cycling stability. A reversible capacity of 700mAhg−1 is sustained at the current of 3Ag−1 after 500 cycles, showing better cycling stability than the bare Co3O4 nanowire arrays (only 150mAhg−1 at the current of 3Ag−1after 100 cycles). Even at a high current of 20Ag−1, the Co3O4@PPy nanowire arrays can still maintain a capacity of 470mAhg−1, which is much higher than that of the bare Co3O4 nanowire arrays (158mAhg−1). The synergetic effect of the arrays structure and the PPy buffer layer contributes to the enhanced electrochemical performance of the Co3O4@PPy nanoarrys. As a result, the introduction of conductive polymer coating layer is an effective strategy to enhance the electrochemical performance of nanoarrays structure for advanced energy storage.