High-Voltage Cathode α-Fe₂O₃ Nanoceramics for Rechargeable Sodium-Ion Batteries

Previously, α-Fe₂O₃ nanocrystals are recognized as anode materials owing to their high capacity and multiple properties. Now, this work provides high-voltage α-Fe₂O₃ nanoceramics cathodes fabricated by the solvothermal and calcination processes for sodium-ion batteries (SIBs). Then, their structure and electrical conductivity were investigated by the first-principles calculations. Also, the SIB with the α-Fe₂O₃ nanoceramics cathode exhibits a high initial charge-specific capacity of 692.5 mA h g^-1 from 2.0 to 4.5 V at a current density of 25 mA g^-1. After 800 cycles, the discharge capacity is still 201.8 mA h g^-1, well exceeding the one associated with the present-state high-voltage SIB. Furthermore, the effect of the porous structure of the α-Fe₂O₃ nanoceramics on sodium ion transport and cyclability is investigated. This reveals that α-Fe₂O₃ nanoceramics will be a remarkably promising low-cost and pollution-free high-voltage cathode candidate for high-voltage SIBs.