Facile fabrication of 3D hierarchically honeycomb-like Na7Fe4.5(P2O7)4@C nanocomposites with enhanced sodium storage performance

In this work, 3D honeycomb-like carbon-coated Na7Fe4.5(P2O7)4 nanocomposites are fabricated by a simple sol-gel method and used as cathode materials for the sodium-ion batteries. The electrochemical results reveal that the 3D hierarchically porous Na7Fe4.5(P2O7)4/C nanocomposites provide a high reversible capacity of 106 mA h g−1 at 0.5 C and a good rate performance (83 mA h g−1 at 2 C). After even 100 cycles at 1 C, 85% of the capacity retentions can be maintained in half batteries. The remarking electrode performance was attributed to the combination of 3D hierarchically porous structure, which facilitates electrolyte penetration into every corner and carbon coating can promote rapid electron transfer.