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

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 (2790 F g) was obtained at 1 A g, and it remained at 430 C g (1122 F g) even at a higher current density of 10 A g. 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 at a power density of 2.5 mW cm with 100% of the original capacitance being retained at a current density of 5 mA cm. Furthermore, the devices exhibited an energy density of 0.24 mW h cm even at a higher power density of 214.4 mW cm, 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.