Structure and interface engineering on polypyrrole-deposited conductive paper originating from nature wood enables high performance flexible all-solid-state supercapacitors

Paper is an ideal substrate for manufacturing flexible electrodes because of its lightweight, inherent mechanical flexibility, and unique structure. However, the traditional bottom-up method of manufacturing paper-based electrode is time-consuming and the active material is easy to fall off. Here, we report a polypyrrole-deposited conductive paper (PCP), which is fabricated by chemical treatment, mechanical compression, and chemical polymerization of natural wood. The post densification process eliminates the vertical arrangement of wood cell cavities, and the formed wood fiber/multi-walled carbon nanotubes hybrid conductive network has high flexibility. The further deposited polypyrrole (PPy) conductive layer can effectively boost the ion transport between electrode/electrolyte interface and increase the active center of interface reaction. Based on the well-designed electrode structure and good interfacial reaction kinetics, the resulting PCP with a PPy mass loading of only 2.4 mg·cm−2 indicates a high areal capacitance of 275.8 mF cm−2 at 20 mV·s−1 and good cycling stability. All-solid-state symmetric supercapacitor exhibits capacitance of 308.3 mF·cm−2. This structure and interface design concept show a promising method for preparing high-performance and scalable biomass-based flexible electronic devices.