Reversible aqueous zinc-ion battery based on ferric vanadate cathode

Rechargeable aqueous zinc - ion batteries have attracted extensive interest because of low cost and high safety. However, the relationship between structure change of cathode and the zinc ion storage mechanism is still complex and challenging. Herein, open - structured ferric vanadate (Fe 2 V 4 O 13 ) has been developed as cathode material for aqueous zinc - ion batteries. Intriguingly, two zinc ion storage mechanism can be observed simultaneously for the Fe 2 V 4 O 13 electrode, i.e. , classical intercalation/deintercalation storage mechanism in the tunnel structure of Fe 2 V 4 O 13 , and reversible phase transformation from ferric vanadate to zinc vanadate, which is verified by combined studies using various in-situ and ex-situ techniques. As a result, the Fe 2 V 4 O 13 cathode delivers a high discharge capacity of 380 mAh/g at 0.2 A/g, and stable cyclic performance up to 1000 cycles at 10 A/g in the operating window of 0.2–1.6 V with 2 mol/L Zn(CF 3 SO 3 ) 2 aqueous solution. Moreover, the assembled Fe 2 V 4 O 13 //Zn flexible quasi - solid - state battery also exhibits a relatively high mechanical strength and good cycling stability. The findings reveal a new perspective of zinc ion storage mechanism for Fe 2 V 4 O 13 , which may also be applicable to other vanadate cathodes, providing a new direction for the investigation and design of zinc - ion batteries. Ferric vanadate (Fe 2 V 4 O 13 ) is developed as cathode material for aqueous zinc-ion batteries. It combines two zinc ion storage mechanism: classical intercalation/deintercalation storage mechanism in the tunnel structure of Fe 2 V 4 O 13 , and reversible phase transformation from ferric vanadate to zinc vanadate.