Tailoring Sodium Iron Hexacyanoferrate/Carbon Nanotube Arrays with 3D Networks for Efficient Sodium Ion Storage

Sodium iron hexacyanoferrate (FeHCF), as Prussian blue, is a promising cathode for sodium ion batteries (SIBs) on account of its open framework structure. Here, FeHCF nanocubes anchored on carbon nanotube (CNT) arrays (FeHCF/CNTs-CC) as integrated electrodes for SIBs have been synthesized via the combination of chemical vapor deposition, immersion–oxidation, and single-iron-source methods. CNT arrays loaded on carbon cloth link FeHCF nanocubes and provide abundant pathways for electrons, as well as a large surface area for sodium ion exchange at the surface of the electrode and electrolyte to facilitate electrochemical kinetics. With the assistance of CNT arrays, FeHCF/CNTs-CC display outstanding high-rate capabilities (135 mA h g⁻¹/0.1 A g⁻¹ and 90 mA h g⁻¹/2 A g⁻¹), and good cycling stability with a capacity retention of 85% after 1000 cycles at 0.5 A g⁻¹.