Sodium-Ion Storage Properties of FeS-Reduced Graphene Oxide Composite Powder with a Crumpled Structure.

The sodium-ion storage properties of FeS-reduced graphene oxide (rGO) and Fe3O4 -rGO composite powders with crumpled structures have been studied. The Fe3 O4 -rGO composite powder, prepared by one-pot spray pyrolysis, could be transformed to an FeS-rGO composite powder through a simple sulfidation treatment. The mean size of the Fe3O4 nanocrystals in the Fe3O4 -rGO composite powder was 4.4 nm. After sulfidation, FeS nanocrystals of size several hundred nanometers were confined within the crumpled structure of the rGO matrix. The initial discharge capacities of the FeS-rGO and Fe3O4 -rGO composite powders were 740 and 442 mA h g(-1), and their initial charge capacities were 530 and 165 mA h g(-1), respectively. The discharge capacities of the FeS-rGO and Fe3O4 -rGO composite powders at the 50th cycle were 547 and 150 mA h g(-1), respectively. The FeS-rGO composite powder showed superior sodium-ion storage performance compared to the Fe3O4 -rGO composite powder.