Low temperature synthesis of carbon encapsulated Fe7S8 nanocrystals as high performance anode for lithium-ion batteries

A novel method is developed for low temperature synthesis of carbon encapsulated spherical Fe7S8 nanocrystals with core shell structure (Fe7S8@C) by the reaction of ferrocene with ammonium persulphate. The phase structure, morphology, specific surface area and composition of the nanocomposite are systematically characterized. It is found that the Fe7S8 nanocrystals with a weight percent of 33.5% have a median size of 25.2 nm. The Fe7S8@C electrodes retain a reversible capacity of 815 and 539 mAh g(-1) after 50 cycles at a current density of 200 and 2284 mA g(-1), respectively. The high capacity, good cycling behavior and rate capability of Fe7S8@C electrodes are attributed to the good protection and electrical conductivity of carbon shell. (C) 2014 Elsevier B.V. All rights reserved.