Three-dimensional nickel vanadium layered double hydroxide nanostructures grown on carbon cloth for high-performance flexible supercapacitor applications

Abstract

This study reports the synthesis of ultrathin Ni–V layered double hydroxide nanosheets on carbon cloth (NVL@CC) through adopting a facile and cost-effective method for flexible supercapacitor applications. The as-synthesized NVL@CC possesses a uniform, mechanically strong and highly ordered porous network with connected pores, ensuring high specific capacitance and enhanced cyclability. A high specific capacity of 1226 C g⁻¹ (2790 F g⁻¹) was obtained at 1 A g⁻¹, and it remained at 430 C g⁻¹ (1122 F g⁻¹) even at a higher current density of 10 A g⁻¹. A hybrid supercapacitor (HSC) was assembled with the NVL@CC electrode as the positive electrode and activated carbon coated carbon cloth as the negative electrode (NVL@CC//AC HSC). The devices showed an excellent energy density of 0.69 mW h cm⁻³ at a power density of 2.5 mW cm⁻³ with 100% of the original capacitance being retained at a current density of 5 mA cm⁻². Furthermore, the devices exhibited an energy density of 0.24 mW h cm⁻³ even at a higher power density of 214.4 mW cm⁻³, surpassing the performances observed for many recently reported flexible supercapacitors. Importantly, the electrochemical performance of the solid-state flexible supercapacitors showed a negligible change upon bending and twisting of the devices. The devices showed no decay in specific capacitance and coulombic efficiency up to 5000 charge–discharge cycles, confirming the excellent cycle life of the HSC device. The performance of NVL@CC indicates the great potential of the material for future flexible energy storage devices.