Wide interlayer spacing ammonium vanadate (NH4)0.37V2O5.0.15(H2O) cathode for rechargeable aqueous zinc-ion batteries

Wide interlayer spacing ammonium vanadate (NH4)0.37V2O5.0.15(H2O) cathode for rechargeable aqueous zinc-ion batteries

Recently, aqueous zinc-ion batteries (AZIBs) have been gaining widespread academic interest in theenergy-storagefield owing to their high energy density, enhanced safety of electrochemical operation,and low cost, as well as the abundance of zinc on earth. The ammonium vanadate group containscompounds that are considered efficient energy-storage materials because they provide twodimensional(2D) layered structures with large interlayer distances that promote the intercalation ofmetal ions during electrochemical processes. Here, we report a hydrated form of ammonium vanadate(NH4)0.37V2O5 0.15(H2O) with a highly crystalline rose-like microstructure, which is used as the positiveelectrode material in AZIBs. The ammonium vanadate cathode delivered an initial capacity of 400 mA hg 1 with 2 M ZnSO4 at the current density of 0.5 Ag 1 in a voltage range from 0.2 V to 1.4 V vs Zn2+/Zn. At ahigher current density (10 A g 1), the material retained 84% of the initial discharge capacity after 1000cycles, while displaying an excellent rate capability. Cyclic voltammetry and ex-situ XRD and XPS areused to study the reaction mechanism of ammonium vanadate cathode in the AZIBs. Unlike otherammonium vanadate’s, (NH4)0.37V2O5 0.15(H2O) undergoes co-intercalation of Zn2+ and H+ along withwater molecules. There is no intermediate irreversible crystal phase formation during the discharge/charge cycles due to expandable interlaying distance. This report suggests that (NH4)0.37V2O5 0.15(H2O)can be an alternative highly stable cathode material for use in AZIBs, and it can be promising for theintercalation of the cathode in larger-sized metal-ion storage systems.

Recently, aqueous zinc-ion batteries (AZIBs) have been gaining widespread academic interest in theenergy-storagefield owing to their high energy density, enhanced safety of electrochemical operation,and low cost, as well as the abundance of zinc on earth. The ammonium vanadate group containscompounds that are considered efficient energy-storage materials because they provide twodimensional(2D) layered structures with large interlayer distances that promote the intercalation ofmetal ions during electrochemical processes. Here, we report a hydrated form of ammonium vanadate(NH4)0.37V2O5 0.15(H2O) with a highly crystalline rose-like microstructure, which is used as the positiveelectrode material in AZIBs. The ammonium vanadate cathode delivered an initial capacity of 400 mA hg 1 with 2 M ZnSO4 at the current density of 0.5 Ag 1 in a voltage range from 0.2 V to 1.4 V vs Zn2+/Zn. At ahigher current density (10 A g 1), the material retained 84% of the initial discharge capacity after 1000cycles, while displaying an excellent rate capability. Cyclic voltammetry and ex-situ XRD and XPS areused to study the reaction mechanism of ammonium vanadate cathode in the AZIBs. Unlike otherammonium vanadate’s, (NH4)0.37V2O5 0.15(H2O) undergoes co-intercalation of Zn2+ and H+ along withwater molecules. There is no intermediate irreversible crystal phase formation during the discharge/charge cycles due to expandable interlaying distance. This report suggests that (NH4)0.37V2O5 0.15(H2O)can be an alternative highly stable cathode material for use in AZIBs, and it can be promising for theintercalation of the cathode in larger-sized metal-ion storage systems.