Remarkable Enhancement in Sodium-Ion Kinetics of NaFe2(CN)6 by Chemical Bonding with Graphene

Abstract

Hexacyanoferrate (Prussian blue, PB)/reduced graphene oxide (PB-RGO) composites with a synergistic structure (graphene/PB/graphene) and a chemical bond are fabricated using a facile one-step method that does not require any external chemical reducing agent. Here, Na4Fe(CN)6 is decomposed in an acidic solution to produce Fe2+ ions, which anchor onto the electronegative graphene oxide (GO) layers by electrostatic interaction and then reduce the GO. The formation of an Fe—O—C chemical bond in the composite results in an excellent rate capability of the PB-RGO composite at room temperature, delivering capacities of78.1, 68.9, and 46.0 mAh g-1 even at the high rates of 10, 20, and 50 C, with a capacity retention of 70.2%, 63.4%, and 41.0%, respectively. The composite also shows an unprecedentedly outstanding cycling stability, retaining =90% of the initial capacity after 600 cycles.