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

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 of 78.1, 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. A well‐organized Prussian blue/reduced graphene oxide (PB‐RGO) composite is synthesized by a facile one‐step method with the evolution of FeOC bonds beneficial for Na‐ion ion kinetics. The PB‐RGO composite shows an excellent rate capability, delivering 78.1, 68.9, and 46.0 mAh g−1 even at 10, 20, and 50 C, respectively, as well as unprecedented cycle life with ≈90% capacity retention over 600 cycles.