Reduced Graphene Oxide-Anchored Manganese Hexacyanoferrate with Low Interstitial H₂O for Superior Sodium-Ion Batteries

Low-cost manganese hexacyanoferrate (NMHCF) possesses many favorable advantages including high theoretical capacity, ease of preparation, and robust open channels that enable faster Na+ diffusion kinetics. However, high lattice water and low electronic conductivity are the main bottlenecks to their pragmatic realization. Here, we present a strategy by anchoring NMHCF on reduced graphene oxide (RGO) to alleviate these problems, featuring a specific discharge capacity of 161/121 mA h g–1 at a current density of 20/200 mA g–1. Moreover, the sodiation process is well revealed by ex situ X-ray diffraction, EIS and Car–Parrinello molecular dynamics simulations. At a rate of 20 mA g–1, the hard carbon//NMHCF/RGO full cell affords a stable discharge capacity of 84 mA h g–1 (based on the weights of cathode mass) over 50 cycles, thus highlighting NMHCF/RGO an alternative cathode for sodium-ion batteries.