Hierarchical polygon Co₃O₄ flakes/N,O-dual doped porous carbon frameworks for flexible hybrid supercapacitors

The core idea of green chemistry is using or converting renewable materials to exploit higher performance. Biomass materials, as low-cost, abundant, eco-friendly, and renewable organic materials, are regarded as ideal and encouraging candidates in various fields. Noteworthy, carbon nanomaterials derived from biomass materials are proposed as promising and potential alternatives for energy materials for their high conductivity, hierarchical porosity and excellent stability. Herein, all biomass-based flexible electrode is designed and prepared, in which kelp and bacterial cellulose (BC) are used as carbon energy resources and flexible substrate, respectively. The design idea is converting two biomass materials into high-performance flexible electrode components. The aqueous hybrid asymmetric supercapacitor reveals high flexibility, excellent stability and considerable electrochemical performance with high energy density and power density of 0.39 mWh cm⁻² (31.8 Wh kg^–1, 6.5 mWh cm⁻³) and 21.7 mW cm⁻² (1768.5 W kg^–1, 361.7 mW cm⁻³), respectively, along with 94.5% capacitance retention after 10,000 cycles, revealing great potential in flexible devices.