Sustainable biowaste strategy to fabricate dual-doped carbon frameworks with remarkable performance for flexible solid-state supercapacitors

Abstract Flexible solid-state supercapacitors show great promise in portable electronics, in which developing advanced electrode materials is a key yet a challenge. This report details an efficient strategy that uses soybean dreg as precursor to purposely prepare nitrogen/oxygen dual-doped porous carbon frameworks by hydrothermal and pyrolysis/activation methods for the first application in flexible solid-state devices. The employed procedure efficiently alleviates the restacking of carbon sheets and well regulates their textural properties and electroactivity to realize outstanding performance. The optimal carbon shows excellent capacitance and rate performance in both three-electrode cell (435 and 336 F g−1 at 0.5 and 50 A g−1) and two-electrode cell (308 and 233 F g−1 at 0.5 and 50 A g−1), which are among the best levels recorded. Significantly, our solid-state supercapacitor achieves integrated high energy and power densities of 9.3 Wh kg−1 and 9883 W kg−1, with a remarkable durability up to 10000 cycles. This device can also work well under various mechanical deformations. For an actual demonstration, two devices are integrated serially, powering a timer for 240 min. This research not only widens the path for designing carbon-based materials, but also brings new idea for device design.