Quadrangular-CNT-Fe3O4-C composite based on quadrilateral carbon nanotubes as anode materials for high performance lithium-ion batteries

A q-CNT-Fe3O4-C composite was synthesized via the homogeneous precipitation of FeOOH nanoparticles on quadrangular carbon nanotubes (q-CNT) substrates. The q-CNT multi-walled carbon nanotube featured one closed end and an open end with a quadrilateral cross section, and the nanotubes were prepared by using co-carbonization method. The FeOOH nanoparticles were encapsulated by amorphous carbon via a hydrothermal treatment and high-temperature calcination of glucose. TEM showed that diameter of the q-CNT was 100 nm and the tube thickness was 20 nm. The outer wall of the q-CNT was attached to Fe3O4 with sizes ranging from 80 to 100 nm via a layer of an amorphous carbon coating. It delivered a specific capacity of 1031.5 mAh g(-1) after 100 cycles at a current density of 200 mA g(-1). After 60 cycles, it showed a high specific capacity of 485.6 mAh g(-1) even at 2000 mA g(-1). CV and EIS results further suggested that the q-CNT-Fe3O4-C composite exhibited lithium ion uptake/release reversibility and a rapid high current charge/discharge capability. The excellent rate performances of the q-CNTFe3O4-C composite can be attributed to the superior electronic transport properties of the quadrilateral CNT with one open end and the synergistic effects of the hybrid components. (C) 2017 Elsevier B.V. All rights reserved.