One-step synthesis of B and N co-doped carbon nanotubes for high-stability lithium-ion batteries

Abstract

Creating adsorption sites by doping heteroatoms into the graphitic structures of carbon electrodes is an effective strategy for improving lithium storage in lithium-ion batteries. In this work, we prepared carbon nanotubes with controllable morphology and controllable nitrogen-doping level by a one-step pyrolysis method through adjusting the amount of urea used during synthesis. Under the synergistic effects of high temperature and Ni-catalyst migration, the carbon nanosheets generated by pyrolysis become coiled into tube-like structures. Characterization using Raman and x-ray photoelectron spectroscopy revealed that the B and N atoms were successfully co-doped into the resultant carbon nanotubes. When the obtained materials were used as lithium-ion battery anodes, reversible specific capacities of 337.11 and 187.62 mA h g−1 were achieved at current densities of 100 and 2000 mA g−1, respectively. Moreover, a capacity of 140.53 mA h g−1 was retained after 2000 cycles at a current density of 2000 mA g−1. The mechanism of lithium storage in these carbon materials was elucidated using cyclic voltammetry tests. Regarding other functional applications, the synthesized composite carbon nanotube material could also be used in other energy-storage battery systems, such as in the sulfur-carrying structures of lithium-sulfur batteries and in the three-dimensional porous structures of sodium batteries.