FeF2@MHCS Cathodes with High Capacity and Fast Sodium Storage Based on Nanostructure Construction

The development of cathode materials with high capacity and superior rate performance is essential for the successful application of future sodium-ion batteries (SIBs). Herein, FeF2@mesoporous hollow carbon spheres are prepared as cathode materials for SIBs. The in situ constructed porous nanocomposites can restrain the particle size, boost the transport of ions/electrons, and buffer the volume change of the electrode materials to yield superior electrochemical performances. The polydopamine-derived carbon matrix can also contribute to the superior capacity through surface oxygen functional groups. The electrode can deliver a capacity reaching 220 mA h g–1 at 0.03 A g–1 and a capacity of 64 mA h g–1 at a high current density of 10 A g–1 and can maintain 112 mA h g–1 after 100 cycles at 0.2 A g–1.