High-energy solid-state asymmetric supercapacitor based on nickel vanadium oxide/NG and iron vanadium oxide/NG electrodes.

Graphical abstract Highlights • Ni 3 V 2 O 8 and Fe 2 VO 4 NPs anchored NG synthesized by simple and cost-effective hydrothermal technique. • Ni 3 V 2 O 8 /NG and Fe 2 VO 4 /NG hybrids are employed as supercapacitor electrodes. • Both electrodes show ultra-high specific capacitance with excellent rate capability and superior cycling stability. • The ASC achieves a high energy density of ∼77.2 W h kg−1 at 863 W kg−1 and an ultra-long cycle life. Abstract Solid-state supercapacitors (SCs) are well-known as one of the most competitive power sources for modern electronics. However, most of the reported solid-state SCs suffer from low specific capacitance and energy density. Herein, a novel strategy for the synthesis of nickel vanadium oxide (Ni 3 V 2 O 8) and iron vanadium oxide (Fe 2 VO 4) nanoparticles (NPs) anchored nitrogen doped graphene (NG) for high energy solid-state asymmetric SC (ACS) through a simple and cost-effective hydrothermal technique was demonstrated. SEM and TEM analysis reveals that active Ni 3 V 2 O 8 and Fe 2 VO 4 NPs with uniform size are anchored on NG sheets. Electrochemical performance of Ni 3 V 2 O 8 /NG and Fe 2 VO 4 /NG electrodes showed that both have ultra-high specific capacitances (∼1898 F g−1 and 590 F g−1 at current density of 1 A g−1, respectively), tremendous rate capabilities, and superior cycling stabilities. Most significantly, solid-state ASC consisting of Ni 3 V 2 O 8 /NG as a cathode and Fe 2 VO 4 /NG as an anode which achieves a high energy density of ∼77.2 W h kg−1 at a power density of 863 W kg−1 and an ultra-long cycle life (capacitance retention of ∼83.3% after 20,000 cycles). This study emphasizes the development of a wide variety of energy storage systems for modern electronics. [ABSTRACT FROM AUTHOR]