Sulfidation of iron confined in nitrogen-doped carbon nanotubes to prepare novel anode materials for lithium ion batteries

Publication date: December 2018Source: New Carbon Materials, Volume 33, Issue 6Author(s): Xin Pan, Yang Liu, Xu-zhen Wang, Zong-bin Zhao, Jie-shan QiuAbstractThe performance of lithium ion batteries (LIBs) is highly dependent on the properties of the anode materials. Developing new carbon materials and metal oxides/sulfides with high capacities has attracted growing attention due to the limited theoretical capacity of commercial graphite. Pyrite (FeS2) is environmental benign, inexpensive and has a high theoretical capacity of 894 mAh g−1 because of its four-electron reduction by lithium, which make it promising for use as an anode material of LIBs. To improve the electrical conductivity and volume change of pyrite, hybrids made of pyrite confined in nitrogen-doped carbon nanotubes (FeS2/N-CNTs) were fabricated by floating catalyst chemical vapor deposition (FCCVD), followed by sulfidation. Results indicate that the original Fe/N-CNTs formed during the FCCVD have iron nanowires or nanorods inside the N-CNTs and their sulfidation with sulfur vapor at 400 °C for 1, 2 and 5 h leads to FeS2/N-CNTs with pyrite contents of 22.4, 45.2, and 55.8 wt%, respectively. The pyrite in FeS2/N-CNTs is in two forms, one is FeS2 nanowires confined in half-open N-CNTs and the other is FeS2 nanoparticles attached to the outer walls of the N-CNTs as a result of diffusion out of the inner tubes. A large number of defects on the N-CNTs tube walls is necessary for the diffusion of sulfur vapor int...
Source: New Carbon Materials - Category: Chemistry Source Type: research