Facile synthesis of metal disulfides nanoparticles encapsulated by amorphous carbon composites as high-performance electrode materials for lithium storage

With the purpose to settle the aggregation and conductivity issues of the active materials, the metal disulfides (MS2, M = Fe, Co) nanoparticles in-situ encapsulated by amorphous carbon layers (MS2@C) have been synthesized by directly vulcanizing the iron (III) acetylacetonate or cobalt (II) acetylacetonate, which are both the metal source and carbon source, using sulfur power as S source and dispersant by a facile one-step heating method. A structure that MS2 nanoparticles are well wrapped by amorphous carbon layer uniformly coated by many ultra-small MS2 nanoparticles is obtained. Benefiting from the unique multidimensional structure that integrates the advantages of low-dimensional nanostructures and high-dimensional bulk structure, FeS2@C and CoS2@C composites evaluated as electrode materials for lithium storage exhibit superior electrochemical performance. After 100 charge-discharge cycles, this novel FeS2@C architecture delivers a reversible capacity of 829 mAh g−1 at 100 mA g−1. Moreover, a high specific capacity of 480 mAh g−1 for FeS2@C at 1000 mA g−1 after 500 cycles is obtained. As for CoS2@C composite, a high specific capacity of 481 mAh g−1 at 500 mA g−1 after 300 cycles is still displayed. This remarkable cycling property and superior rate capability demonstrate the potential applications for next-generation lithium-ion batteries.