A polypyrrole-adorned, self-supported, pseudocapacitive zinc vanadium oxide nanoflower and nitrogen-doped reduced graphene oxide-based asymmetric supercapacitor device for power density applications

Abstract

Herein, a distinctive approach has been implemented for exploiting a typical battery material zinc vanadium oxide (ZV) as a supercapacitor electrode material. Aiming to achieve fascinating capacitive properties, a hybrid (ZnV₂O₆@PPy) of the conducting polymer polypyrrole (PPy)-decorated ZV was synthesized via a hydrothermal protocol, followed by low-temperature in situ oxidative polymerization. The hybrid electrode ZnV₂O₆@PPy (ZVP) benefited from its interconnecting network architecture, mesoporous feature, conductive feature, and rich redox chemistry, which contributed to the charge storage performance to ensure a remarkable specific capacitance (C_s) of 723.6 F g⁻¹ at 1 A g⁻¹ current density that outweighed the C_s of ZV at 402 F g⁻¹. Moreover, an asymmetric supercapacitor (ASC) device (based on ZnV₂O₆@PPy as the positive electrode and the nitrogen-doped reduced graphene oxide (NG) as the negative electrode) delivered a maximum C_s of 109.2 F g⁻¹ at 1 A g⁻¹ within an impressive voltage window of 0–1.5 V. The ASC provided a maximum energy density of 34 W h kg⁻¹ at a power density of 748.7 W kg⁻¹, maintaining a reliable cycle life of 93% over 3000 galvanostatic charge–discharge cycles. Two serially associated ASC devices can power up the red LED indicator for quite a long time. The comprehensive experimental output of the ASC supports the promising application of the device as a supercapacitor electrode application.