Enhanced Electrochemical Performance of CNTs/α-Fe₂O₃/PPy Composite as Anode Material for Lithium Ion Batteries

Abstract

A novel CNTs/α-Fe2O3/PPy composite with three-dimensional interconnected network structure is successfully synthesized through a solvothermal method and in-situ polymerization. The as-synthesized CNTs/α-Fe2O3/PPy composite is characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The results indicate that spherical α-Fe2O3 particles are densely anchored onto the three-dimensional CNTs conducting network, and the outer PPy layer deposits uniformly on the surface of α-Fe2O3 particles. As an anode material for lithium-ion battery, the CNTs/α-Fe2O3/PPy composite exhibits a high initial coulombic efficiency of 75.6%, a high specific capacity of 1095.4 mAh·g–1 at a current rate of 100 mA·g–1 after 50 cycles, as well as a good rate capability at elevated current rates. Compared with pure α-Fe2O3, the improved Li storage property could be ascribed to the synergistic effects of α-Fe2O3, CNTs and PPy layer. This unique structure not only possesses excellent conductivity under the joint effect of inner randomly distributed CNTs and outer coated PPy layer, which effectively shortens the transfer paths of lithium ions and reduces the contact resistance, but also the outer PPy protective layer prevents agglomeration of α-Fe2O3 upon cont inuous charging/discharging, which withstands huge stresses caused by α-Fe2O3 expansion/extraction. T he CNTs/α-Fe2O3/PPy composite has the potential for use as high-performance anode electrode for Li-ion batteries.