CNTs in Situ Attached to α‑Fe₂O₃ Submicron Spheres for Enhancing Lithium Storage Capacity

In this work, we developed a facile hydrothermal method for synthesis of hybrid α-Fe₂O₃–carbon nanotubes (CNTs) architectures (α-Fe₂O₃–CNTs-1 and α-Fe₂O₃–CNTs-2). The CNTs are in situ attached to the α-Fe₂O₃ submicron spheres and form three-dimensional network robust architectures. The increase in the amount of CNTs in the network α-Fe₂O₃–CNTs architectures will significantly enhance the cycling and rate performance, as the flexible and robust CNTs could ensure the fast electron transport pathways, enhance the electronic conductivity, and improve the structural stability of the electrode. As for pure α-Fe₂O₃ submicron spheres, the capacity decreased significantly and retained at 377.4 mAh g^–1 after 11 cycles, and the capacity has a slightly increasing trend at the following cycling. In contrast, the network α-Fe₂O₃–CNTs-2 electrode shows the most remarkable performance. At the 60th cycle, the capacity of network α-Fe₂O₃–CNTs-2 (764.5 mAh g^–1) is 1.78 times than that of α-Fe₂O₃ submicron spheres (428.3 mAh g^–1). The long-term cycling performance (1000 cycles) of samples at a high current density of 5 C showed that the capacity of α-Fe₂O₃ submicron spheres fade to ∼37.3 mAh g^–1 at the 400th cycle and gradually increased to ∼116.7 mAh g^–1 at the 1000th cycle. The capacity of network α-Fe₂O₃–CNTs-2 maintained at ∼220.2 mAh g^–1 before the 400th cycle, arrived at ∼326.5 mAh g^–1 in the 615th, cycle and retained this value until 1000th cycle. The network α-Fe₂O₃–CNTs-2 composite could significantly enhance the cycling and rate performance than pure α-Fe₂O₃ submicron spheres composite