Improved electrochemical performances of binder-free CoMoO4 nanoplate arrays@Ni foam electrode using redox additive electrolyte

• Cobalt molybdate NPAs on nickel foam was synthesized by hydrothermal method.
• The prepared CoMoO4 NPAs on nickel foam are binder and conductive agents free.
• High areal capacity of 603 μAh cm−2 was achieved at 2.5 mA cm−2 using redox additive.
• Assembled asymmetric device shows excellent energy density and cyclic stability.

Herein, we are successfully prepared cobalt molybdate (CoMoO4) grown on nickel foam as a binder free electrode by hydrothermal approach for supercapacitors and improved their electrochemical performances using potassium ferricyanide (K3Fe(CN)6) as redox additive. The formation of CoMoO4 on Ni foam with high crystallinity is confirmed using XRD, Raman, and XPS measurements. The nanoplate arrays (NPAs) of CoMoO4 are uniformly grown on Ni foam which is confirmed by FE-SEM analysis. The prepared binder-free CoMoO4 NPAs achieved maximum areal capacity of 227 μAh cm−2 with KOH electrolyte at 2.5 mA cm−2. This achieved areal capacity is further improved about three times using the addition of K3Fe(CN)6 as redox additive. The increased electrochemical performances of CoMoO4 NPAs on Ni foam electrode via redox additive are discussed in detail and the mechanism has been explored. Moreover, the assembled CoMoO4 NPAs on Ni foam//activated carbon asymmetric supercapacitor device with an extended operating voltage window of 1.5 V exhibits an excellent performances such as high energy density and cyclic stability. The overall performances of binder-free CoMoO4 NPAs on Ni foam with redox additives suggesting their potential use as positive electrode material for high performance supercapacitors.

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