Structural design enabled a hypotoxic NaFeV(PO) cathode with ultra-fast and ultra-long sodium storage.

Among various cathode materials for sodium-ion batteries, NaV(PO) has attracted much attention due to its outstanding electrochemical performance. However, the toxicity and expensive price of vanadium limit its practical application. Therefore, the substitution of vanadium with nontoxic and inexpensive transition metal elements is significant.

Active-Site-Specific Structural Engineering Enabled Ultrahigh Rate Performance of the NaLiFe(PO)(PO) Cathode for Lithium-Ion Batteries.

Iron-based mixed-polyanionic cathode NaFe(PO)(PO) (NFPP) has advantages of environmental benignity, easy synthesis, high theoretical capacity, and remarkable stability. From NFPP, a novel Li-replaced material NaLiFe(PO)(PO) (NLFPP) is synthesized through active Na-site structural engineering by an electrochemical ion exchange approach. The NLFPP cathode can show high reversible capacities of 103.

Hollow-Sphere-Structured NaFe(PO)(PO)/C as a Cathode Material for Sodium-Ion Batteries.

The mixed polyanionic material NaFe(PO)(PO) combines the advantages of NaFePO and NaFePO in capacity, stability, and cost. Herein, we synthesized carbon-coated hollow-sphere-structured NaFe(PO)(PO) powders by a scalable spray drying route. The optimal sample can deliver a high discharge capacity of 107.

Size-controlled synthesis of hierarchical nanoporous iron based fluorides and their high performances in rechargeable lithium ion batteries.

High performance nanostructured iron fluorides with controllable sizes were successfully synthesized using oleylamine as a size tuning agent for the first time. They exhibited excellent cathode performances with large retensive capacities exceeding 200 mA h g(-1) after 50 cycles and outstanding rate performances of nearly 100 mA h g(-1) even at 10 C.