Synergistic optimization of polypyrrole/mulberry paper-based composite electrode by carbon black and multi-walled carbon nanotubes for high-performance flexible all-solid-state supercapacitors

Mulberry paper (MP) is an ideal substrate for fabricating electrodes with high specific capacitance and flexibility. In this paper, carbon black (CB) and aminated multi-walled carbon nanotubes (AMWCNTs) are used as the substrate of MP, which improves the specific capacitance, mechanical flexibility and safety properties of paper-based electrode composites. The polypyrrole (PPy) is loaded onto the composites to improve the low loading of polypyrrole on MP and the excessive resistance of the electrodes through synergistic effects. The paper-based electrode (CB/AMWCNTs/PPy-MP) obtained by a three-step simple process not only has a remarkable area specific capacitance of 2223 mF cm−2 at 2 mA cm−2, but also has good mechanical toughness, environmental stability and flame retardant properties. An all-solid-state supercapacitor with an area specific capacitance of 471.2 mF cm−2 is assembled by composite electrodes, and the maximum energy and power densities are 21.39 μWh cm−2 and 4.58 mW cm−2, respectively, and it could be bent from 0° to 90° without affecting its performance. This provides an effective method for preparing renewable flexible energy storage devices. © 2025 Elsevier Ltd