Targeted interfacial anchoring and wrapping of Fe3O4 nanoparticles onto graphene by PPy-derived-carbon for stable lithium-ion battery anodes

Combining graphene with iron oxide has shown great promise in mitigating the pulverization of iron-oxide anode during fast charge/discharge in lithium-ion batteries. However, the attachment between hydrophilic iron oxide and hydrophobic graphene sheets could potentially compromise during cycling, affecting its cycling stability. By exploiting the polymerization characteristics of pyrrole, we anchor and subsequently wrap the Fe(OH) 3 colloidal nanoparticles onto graphene oxide surface with polypyrrole. The composite is further annealed to give polypyrrole-derived-carbon (PPy-C) wrapped Fe 3 O 4 @graphene (Fe 3 O 4 @graphene@PPy-C). PPy-C strengthens the interaction between the Fe 3 O 4 and the graphene and helps preserving the structural integrity during cycling. As an anode material, Fe 3 O 4 @graphene@PPy-C composite exhibits a high reversible capacity of 721 mA h g −1 over 320 cycles at a current density of 0.2 A g −1 . Even at a high current density of 2 A g −1 , the electrode still achieves a high capacity of 406 mA h g −1 . This strategy provides a new alternative to improve the cycling stability of iron-oxide/carbon composite anodes.