Impacts of fluorine in NASICON‐type materials as cathodes for aqueous zinc ion batteries
Ziyan Liu, Xiaoxiao Jia, Guozhong Cao
Abstract
Abstract Sodium superionic conductor (NASICON)‐type materials are getting more and more attention due to their high capacity and good cycling ability compared with other cathode materials in aqueous zinc ion batteries (AZIB). The present paper was to study the synthesis and electrochemical properties of two NASICON compounds of Na 3 V 2 (PO 4 ) 3 and Na 3 V 2 (PO 4 ) 2 F 3 and to understand the impacts of fluorine. Both Na 3 V 2 (PO 4 ) 3 and Na 3 V 2 (PO 4 ) 2 F 3 are synthesized by hydrothermal growth followed with annealing at 800°C in inert gas. With 3 mol/L Zn(CF 3 SO 3 ) 2 in water as electrolyte, Na 3 V 2 (PO 4 ) 3 offered a high storage capacity, while Na 3 V 2 (PO 4 ) 2 F 3 demonstrated a high discharge voltage though low storage capacity. It was also found that the storage capacity of Na 3 V 2 (PO 4 ) 2 F 3 increases with increased cycles; however, the compound undergoes a gradual phase transition. It is discussed possible approaches to attain both high discharge voltage and large capacity with good cycling stability.