High-performance flexible asymmetric supercapacitor utilizing hierarchical NiCo2O4 nanosheets supported on porous carbonized Verbena leaves.

This study employed three-dimensional porous carbon with high surface area as the conductive substrate for composite electrode materials, aiming to facilitate rapid charge transfer and ion diffusion to increase the specific capacitance of pseudo-capacitive materials. We employed an in-situ hydrothermal method to anchor NiCo 2 O 4 onto the porous carbonized verbena leaves, yielding nanostructured VC@NiCo 2 O 4 -8 composite electrode materials. At a current density of 1.0 A g-1, VC@NiCo 2 O 4 -8 exhibited a high specific capacitance of up to 2061.8 F g−1 and remarkable cycling stability (with only 7.8 % capacitance loss after 10000 cycles). Additionally, we assembled VC@NiCo 2 O 4 -8//VC asymmetric all-solid-state flexible supercapacitors, attaining a significant energy density of 54.0 Wh kg−1 at a power density of 695 W kg−1, while maintaining good flexibility and stability. This study provides a simple and effective method for the design and construction of high-performance electrode materials for flexible energy storage devices. [Display omitted] • VC@NiCo 2 O 4 -8 synthesized by in-situ hydrothermal method with carbonized verbena. • VC@NiCo 2 O 4 -8 showed a high specific capacitance of 2061.8 F g−1 at 1.0 A g−1. • All-solid-state SCs exhibited an energy density of 54.0 Wh kg−1 at 695 W kg−1. • VC@NiCo 2 O 4 -8//VC device demonstrated excellent flexibility and stability. [ABSTRACT FROM AUTHOR]