Wastepaper-derived porous carbon supported cobalt nanocomposites for all solid-state flexible supercapacitor

The conversion of wastepaper into high-value carbon materials has gained significant attention as a sustainable strategy for energy storage applications. Owing to its low cost, abundance, and intrinsic fibrous structure, wastepaper serves as an attractive precursor for carbon-based electrode materials. In this work, a novel electrode comprising cobalt nanoparticles and Co 3 O 4 embedded in wastepaper-derived porous carbon has been developed for use in a flexible all-solid-state asymmetric supercapacitor. The integration of cobalt nanoparticles and Co 3 O 4 introduces redox-active centres, which enhance the electrochemical activity of the carbon framework. Meanwhile, the interconnected porous and conductive carbon network enables rapid ion diffusion and efficient electron transport, synergistically improving the overall electrochemical performance. It delivers a high specific capacitance of 61.5 F g −1 , a power density of 5143 W kg −1 , and an energy density of 9 Wh kg −1 at a current density of 2.5 A g −1 . Furthermore, the device maintains outstanding cycling stability, retaining 82.86 % of its capacitance after 10,000 charge-discharge cycles. Practical applicability is confirmed through its ability to power a red LED, showcasing its potential in flexible electronics. This approach not only enhances the value of waste materials but also offers a sustainable route for developing high-performance, flexible energy storage devices. • Wastepaper converted into porous carbon for flexible supercapacitors. • Co NPs/Co 3 O 4 introduce redox centres enhancing charge storage capacity. • WP/Co-1.0 shows high capacitance (61.5 F g −1 ) and energy density (9 Wh kg −1 ). • Flexible solid-state device powers LED, proving real-world applicability.