A nanoarchitectured Na 6 Fe 5 (SO 4 ) 8 /CNTs cathode for building a low-cost 3.6 V sodium-ion full battery with superior sodium storage

A novel high-voltage cathode material Na 6 Fe 5 (SO 4 ) 8 (NFS) is successfully prepared for sodium-ion batteries for the first time. It is found that the NFS cathode shows a high working voltage of 3.7 V, together with an attractive energy density approaching 450 W h kg −1 . And, based on an NFS@5%CNTs cathode and hard carbon (HC) anode, a full NFS@5%CNTs//HC cell can deliver an impressive energy density approaching 350 W h kg −1 and excellent cycling stability over 1000 cycles at 2C.